Projection method, projection system, and program

Abstract

To provide a projection method capable of reducing such a risk that a projection image cannot be projected because a place which satisfies conditions of brightness cannot be found.SOLUTION: A projection method includes processes of: projecting a first image in a first region with a first projector; projecting a second image in a second region different from the first region with a second projector; acquiring first brightness information indicating the brightness in the first region; and stacking a fourth image identical to the first image on top of the first image in the first region with the second projector when the first brightness information satisfies a first condition.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a projection method, a projection system, and a program.

Background Art

[0002] Patent Document 1 discloses a mobile projection device that determines a location that satisfies a condition that the brightness is equal to or less than a predetermined threshold as a projection location of a projection image. When it is determined that the brightness of a predetermined location is not equal to or less than the predetermined threshold, this mobile projection device searches for another location.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 does not disclose what operation the mobile projection device performs when a location that satisfies the condition cannot be found within the area where the mobile projection device can project a projection image. Therefore, with the mobile projection device of Patent Document 1, there is a possibility that a projection image cannot be projected when a location that satisfies the condition cannot be found.

Means for Solving the Problems

[0005] A projection method according to one aspect of the present invention includes: a first projector projecting a first image onto a first area; a second projector projecting a second image onto a second area different from the first area; acquiring first brightness information indicating the brightness of the first area; and when the first brightness information satisfies a first condition, in the first area, the second projector stacking a fourth image identical to the first image on the first image.

[0006] One aspect of the projection system of the present invention includes a sensor that outputs a signal indicating the brightness of a first area, projects a first image onto the first area, and acquires first brightness information indicating the brightness of the first area based on the signal output from the sensor. A first projector that performs the above operations, and a second projector that stacks a fourth image identical to the first image on the first image in the first area when the first brightness information satisfies a first condition.

[0007] One aspect of the program of the present invention causes a computer to cause a first projector to project a first image onto a first area, cause a second projector to project a second image onto a second area different from the first area, acquire first brightness information indicating the brightness of the first area, and cause the second projector to stack a fourth image identical to the first image on the first image in the first area when the first brightness information satisfies a first condition.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Figure 30

Figure 31

Figure 32

Figure 33

Figure 34

Figure 35

Figure 36

Figure 37

Figure 38

Figure 39

Figure 40

Mode for Carrying Out the Invention

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each of the following drawings, for ease of viewing of each component, the scale of the dimensions may be shown differently depending on the component.

[0010] [First Embodiment] First, the first embodiment of the present disclosure will be described. FIG. 1 is a diagram schematically showing a projection system 100 in the first embodiment. As shown in FIG. 1, the projection system 100 includes a first projector 1A, a second projector 1B, and a video supply device 2. The first projector 1A is connected to the video supply device 2 via a first communication cable 3. The second projector 1B is connected to the first projector 1A via a second communication cable 4.

[0011] The video supply device 2 supplies a first video signal to the first projector 1A. Further, the video supply device 2 supplies a second video signal to the second projector 1B via the first projector 1A. For example, the video supply device 2 is a personal computer, a tablet terminal, or a DVD player (Digital Versatile Disc), etc.

[0012] The first projector 1A projects a first image 300A onto a first area 400A based on the first video signal supplied from the video supply device 2 via the first communication cable 3. The first area 400A is an area included in a first projection surface such as a projection screen or a wall surface. The first projector 1A transmits the second video signal supplied from the video supply device 2 via the first communication cable 3 to the second projector 1B via the second communication cable 4.

[0013] The second projector 1B projects a second image 300B onto a second area 400B different from the first area 400A based on the second video signal supplied from the video supply device 2 via the first projector 1A. The second area 400B is an area included in a second projection surface such as a projection screen or a wall surface. The second projection surface may be the same projection surface as the first projection surface or a different projection surface from the first projection surface.

[0014] The second image 300B may be the same image as the first image 300A or a different image from the first image 300A. In other words, the second video signal supplied to the second projector 1B may be the same video signal as the first video signal supplied to the first projector 1A or a different video signal from the first video signal.

[0015] Note that in FIG. 1, for convenience of explanation, an example where the first area 400A and the second area 400B are adjacent to each other in the horizontal direction is shown, but the positional relationship between the first area 400A and the second area 400B is not limited to the example shown in FIG. 1.

[0016] Next, with reference to FIGS. 2 to 4, the configurations of the first projector 1A and the second projector 1B will be described. The configurations of the first projector 1A and the second projector 1B are the same. Therefore, hereinafter, the first projector 1A and the second projector 1B will be collectively referred to as the "projector 1", and the configuration of the projector 1 will be described.

[0017] FIG. 2 is a perspective view schematically showing the appearance of the projector 1. FIG. 3 is a side view of the projector 1 shown in FIG. 1. As shown in FIGS. 2 and 3, the projector 1 includes a projector main body 10, a pedestal 20, and a driving device 30.

[0018] The projector main body 10 projects the image light L. As an example, the projector main body 10 is a hexahedron having six planes. On the front surface 11 of the projector main body 10, a light emitting unit 12 that emits the image light L generated inside the projector main body 10 is provided. In the following description, the direction in which the image light L is projected from the projector main body 10 will be referred to as the "projection direction Dp". For example, the projection direction Dp is a direction orthogonal to the front surface 11 of the projector main body 10 and a direction away from the projector main body 10.

[0019] The pedestal 20 is a support member for installing the projector main body 10 at a predetermined location. The pedestal 20 supports the projector main body 10 and the driving device 30. As an example, the pedestal 20 has a disk shape. The driving device 30 is disposed on the upper surface 21 of the pedestal 20, and the pedestal 20 is connected to the lower surface 13 of the projector main body 10 via the driving device 30.

[0020] The driving device 30 directs the direction in which the image light L is projected, that is, the projection direction Dp, in a predetermined direction. Specifically, as shown in FIG. 3, the driving device 30 rotates the projector main body 10 around at least one of the yaw axis Y and the pitch axis X to direct the projection direction Dp in a predetermined direction. The driving device 30 includes a first rotating device 31 and a second rotating device 32.

[0021] The first rotating device 31 rotates the projector main body 10 around the yaw axis Y. As an example, the first rotating device 31 has a cylindrical shape with a diameter smaller than that of the pedestal 20. The first rotating device 31 is disposed on the upper surface 21 of the pedestal 20 in a state where its central axis coincides with the central axis of the pedestal 20. The central axis of the first rotating device 31 is the yaw axis Y. When the first rotating device 31 rotates around the yaw axis Y, the projector main body 10 also rotates around the yaw axis Y.

[0022] The second rotating device 32 rotates the projector main body 10 around the pitch axis X. As an example, the second rotating device 32 has a semi-cylindrical shape. Among the surfaces of the second rotating device 32, the surface extending in the radial direction of the second rotating device 32 is connected to the lower surface 13 of the projector main body 10. The second rotating device 32 is disposed on the upper end surface of the first rotating device 31 in a state where its central axis is orthogonal to the yaw axis Y. The central axis of the second rotating device 32 is the pitch axis X. When the second rotating device 32 rotates around the pitch axis X, the projector main body 10 also rotates around the pitch axis X.

[0023] The operation of the drive device 30 configured as described above is controlled by a processor 90 described later. That is, each of the rotation operation of the first rotating device 31 around the yaw axis Y and the rotation operation of the second rotating device 32 around the pitch axis X is controlled by the processor 90. More specifically, the yaw angle θ which is the rotation angle of the first rotating device 31 around the yaw axis Y and the pitch angle α which is the rotation angle of the second rotating device 32 around the pitch axis X are each controlled by the processor 90, whereby the projection direction Dp is directed in a predetermined direction. Thus, in the present embodiment, the projection direction Dp of the projector 1 is variable.

[0024] FIG. 4 is a block diagram schematically showing the functional configuration of the projector 1. As shown in FIG. 4, the projector main body 10 includes an optical device 40, an input device 50, a camera 60, a communication device 70, a storage device 80, and a processor 90.

[0025] The optical device 40 is controlled by the processor 90 to generate image light L representing a color image, and projects the generated image light L in the projection direction Dp. The optical device 40 includes a first image generation panel 41, a second image generation panel 42, a third image generation panel 43, a dichroic prism 44, and a projection optical system 45.

[0026] The first image generation panel 41 generates red image light LR representing a red image and emits it to the dichroic prism 44. The first image generation panel 41 has a plurality of pixels arranged in a matrix, and each of the plurality of pixels emits red light. By controlling the emission light amount of red light for each pixel by the processor 90, red image light LR is emitted from the first image generation panel 41.

[0027] The second image generation panel 42 generates green image light LG representing a green image and emits it to the dichroic prism 44. The second image generation panel 42 has a plurality of pixels arranged in a matrix, and each of the plurality of pixels emits green light. By controlling the emission light amount of green light for each pixel by the processor 90, green image light LG is emitted from the second image generation panel 42.

[0028] The third image generation panel 43 generates blue image light LB representing a blue image and emits it to the dichroic prism 44. The third image generation panel 43 has a plurality of pixels arranged in a matrix, and each of the plurality of pixels emits blue light. By controlling the emission light amount of blue light for each pixel by the processor 90, blue image light LB is emitted from the third image generation panel 43.

[0029] For example, each of the image generation panels 41, 42, and 43 is a self-emitting electro-optical device such as an OLED (Organic Light Emitting Diode) panel or a μLED (Micro Light Emitting Diode) panel. Note that each of the image generation panels 41, 42, and 43 may be a non-self-emitting electro-optical device such as a liquid crystal panel or a DMD (Digital Micromirror Device). When each of the image generation panels 41, 42, and 43 is a non-self-emitting electro-optical device, light from a light source (not shown) such as an LED is separated into red light, green light, and blue light, respectively. The red light is incident on the first image generation panel 41. The green light is incident on the second image generation panel 42. The blue light is incident on the third image generation panel 43. Also, a single image generation panel may be used to emit light of each color in a time-division manner.

[0030] The dichroic prism 44 synthesizes the red image light LR, the green image light LG, and the blue image light LB to generate image light L representing a color image and emits it to the projection optical system 45. The projection optical system 45 is composed of a plurality of optical elements such as lenses, and enlarges and projects the image light L emitted from the dichroic prism 45 in the projection direction Dp. Although not shown in the figure, the projection optical system 45 is provided with a mechanism capable of adjusting optical parameters such as the lens shift amount, the lens focus amount, and the lens zoom amount. By controlling these mechanisms by the processor 90, the optical parameters of the projection optical system 45 are adjusted.

[0031] The input device 50 is a device that receives user input operations for the projector main body 10. As an example, the input device 50 includes an operation unit 51 and a light receiving unit 52. The operation unit 51 is composed of a plurality of operation keys provided on the projector main body 10. For example, the operation keys include a power key, a menu call key, a direction key, a determination key, and a volume adjustment key, etc. The operation keys may be hardware keys or software keys displayed on a touch panel provided on the projector main body 10. The operation unit 51 outputs the electrical signal generated when each operation key is operated by the user as an operation signal to the processor 90.

[0032] The light receiving unit 52 includes a photoelectric conversion circuit that receives infrared light transmitted from a remote controller (not shown) of the projector main body 10 and converts it into an electrical signal. The light receiving unit 52 outputs the electrical signal obtained by the photoelectric conversion of the infrared light as a remote operation signal to the processor 90. The remote controller is provided with a plurality of operation keys similar to the operation unit 51. The remote controller converts the electrical signal generated when each operation key provided on the remote controller is operated by the user into infrared light and transmits it to the projector main body 10. That is, the remote operation signal output from the light receiving unit 52 is substantially the same as the electrical signal generated when each operation key of the remote controller is operated by the user. When the remote controller transmits a radio wave signal according to a short-range wireless communication standard such as Bluetooth (registered trademark), a receiving device for receiving the radio wave signal may be provided instead of the light receiving unit 52.

[0033] The camera 60 is arranged on the projector main body 10 in a state where the shooting direction coincides with the projection direction Dp. The camera 60 shoots a landscape included within the angle of view of the camera 60 in accordance with a shooting command signal output from the processor 90 to the camera 60, and outputs a shooting image signal indicating the shooting image to the processor 90. The camera 60 may be arranged on the surface of the housing of the projector main body 10, or may be arranged inside the housing of the projector main body 10. The camera 60 included in the first projector 1A is an example of a sensor that outputs a signal indicating the brightness of the first region 400A. That is, the projection system 100 includes the camera 60 as a sensor that outputs a signal indicating the brightness of the first region 400A.

[0034] The communication device 70 relays communication between the processor 90 and an external device. When the projector 1 is the first projector 1A, the communication device 70 relays communication between the processor 90 and the video supply device 2. When the projector 1 is the second projector 1B, the communication device 70 relays communication between the processor 90 and the first projector 1A.

[0035] The storage device 80 includes a non-volatile memory that stores programs and various setting data necessary for causing the processor 90 to execute various processes, and a volatile memory that is used as a temporary storage destination for data when the processor 90 executes various processes. For example, the non-volatile memory is an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory, etc. The volatile memory is, for example, a RAM (Random Access Memory), etc.

[0036] The processor 90 is an arithmetic processing unit that controls the operations of the projector main body 10 and the drive device 30 according to a program pre-stored in the storage device 80. For example, the processor 90 is composed of one or more CPUs (Central Processing Units). Part or all of the functions of the processor 90 may be composed of circuits such as DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), and FPGA (Field Programmable Gate Array). The processor 90 executes various processes in parallel or sequentially.

[0037] Hereinafter, for convenience of explanation, the projector main body 10, the drive device 30, the optical device 40, the input device 50, the camera 60, the communication device 70, the storage device 80, and the processor 90 included in the first projector 1A may be referred to as the first projector main body 10A, the first drive device 30A, the first optical device 40A, the first input device 50A, the first camera 60A, the first communication device 70A, the first storage device 80A, and the first processor 90A.

[0038] Similarly, the projector main body 10, the drive device 30, the optical device 40, the input device 50, the camera 60, the communication device 70, the storage device 80, and the processor 90 included in the second projector 1B may be referred to as the second projector main body 10B, the second drive device 30B, the second optical device 40B, the second input device 50B, the second camera 60B, the second communication device 70B, the second storage device 80B, and the second processor 90B.

[0039] Subsequently, the operation of the projection system 100 configured as described above will be described. When the first processor 90A of the first projector 1A receives a first operation to turn on the power of the first projector 1A via the first input device 50A, the first processor 90A executes a first initial process.

[0040] FIG. 5 is a flowchart showing a first initial process executed by the first processor 90A. When the first processor 90A receives a first operation, it reads and executes a program from the first storage device 80A to execute the first initial process shown in FIG. 5.

[0041] As shown in FIG. 5, when starting the first initial process, the first processor 90A controls the first driving device 30A to direct the projection direction Dp of the first projector 1A toward the center position of the first area 400A (step S1).

[0042] The first storage device 80A stores in advance a first yaw angle θ1 and a first pitch angle α1 for directing the projection direction Dp of the first projector 1A toward the center position of the first area 400A. In step S1, the first processor 90A controls the first driving device 30A so that the yaw angle θ and the pitch angle α of the first projector main body 10A match the first yaw angle θ1 and the first pitch angle α1, thereby directing the projection direction Dp of the first projector 1A toward the center position of the first area 400A.

[0043] Note that when starting the first initial process, if the projection direction Dp of the first projector 1A is already directed toward the center position of the first area 400A, the first processor 90A may skip step S1.

[0044] Then, the first processor 90A controls the first optical device 40A based on the first video signal received from the video supply device 2 via the first communication device 70A to project the first image 300A onto the first area 400A (step S2). After projecting the first image 300A onto the first area 400A, the first processor 90A ends the first initial process.

[0045] The first image 300A is an image generated based on the first video signal. Projecting the first image 300A onto the first area 400A means projecting the image light L representing the first image 300A onto the first area 400A. When the image light L representing the first image 300A is projected onto the first area 400A, the first image 300A is displayed in the first area 400A.

[0046] As described above, when the first projector 1A receives the first operation, it projects the first image 300A onto the first area 400A. Note that the first processor 90A may perform distortion correction such as trapezoidal correction on the first image 300A generated by the first optical device 40A so that a rectangular first image 300A is displayed in the first area 400A. The above is the description of the first initial process executed by the first processor 90A.

[0047] When the second processor 90B of the second projector 1B receives a second operation to turn on the power of the second projector 1B via the second input device 50B, it executes a second initial process.

[0048] FIG. 6 is a flowchart showing the second initial process executed by the second processor 90B. When the second processor 90B receives the second operation, it reads and executes a program from the second storage device 80B to execute the second initial process shown in FIG. 6.

[0049] As shown in FIG. 6, when starting the second initial process, the second processor 90B controls the second driving device 30B to direct the projection direction Dp of the second projector 1B toward the center position of the second area 400B (step S3).

[0050] The second memory device 80B stores in advance a second yaw angle θ2 and a second pitch angle α2 for directing the projection direction Dp of the second projector 1B toward the center position of the second area 400B. In step S3, the second processor 90B controls the second drive device 30B so that the yaw angle θ and the pitch angle α of the second projector main body 10B match the second yaw angle θ2 and the second pitch angle α2, thereby directing the projection direction Dp of the second projector 1B toward the center position of the second area 400B.

[0051] Note that when the projection direction Dp of the second projector 1B is already directed toward the center position of the second area 400B when the second processor 90B starts the second initial process, step S3 may be skipped.

[0052] Then, the second processor 90B controls the second optical device 40B based on the second video signal received from the video supply device 2 via the second communication device 70B, thereby projecting the second image 300B onto the second area 400B (step S4). After projecting the second image 300B onto the second area 400B, the second processor 90B ends the second initial process.

[0053] The second image 300B is an image generated based on the second video signal. Projecting the second image 300B onto the second area 400B means projecting the image light L representing the second image 300B onto the second area 400B. When the image light L representing the second image 300B is projected onto the second area 400B, the second image 300B is displayed in the second area 400B.

[0054] As described above, when the second projector 1B receives the second operation, it projects the second image 300B onto the second area 400B. Note that the second processor 90B may perform distortion correction such as trapezoidal correction on the second image 300B generated by the second optical device 40B so that the rectangular second image 300B is displayed in the second area 400B. The above is the description of the second initial process executed by the second processor 90B.

[0055] After the first processor 90A finishes the first initial process, it executes the first determination process at predetermined time intervals. FIG. 7 is a flowchart showing the first determination process executed by the first processor 90A. The first processor 90A executes the first determination process shown in FIG. 7 by reading and executing a program from the first storage device 80A.

[0056] As shown in FIG. 7, when the first processor 90A starts the first determination process, first, it outputs a shooting command signal to the first camera 60A to obtain a shooting image signal indicating a captured image of the first area 400A from the first camera 60A (step S5).

[0057] After the power of the first projector 1A is turned on, since the projection direction Dp of the first projector 1A is directed to the center position of the first area 400A, the shooting direction of the first camera 60A is also directed to the center position of the first area 400A. Therefore, after the power of the first projector 1A is turned on, the first area 400A is within the angle of view of the first camera 60A. When the first camera 60A receives a shooting command signal from the first processor 90A, it shoots the first area 400A within the angle of view and outputs a shooting image signal indicating a captured image of the first area 400A to the first processor 90A.

[0058] Subsequently, the first processor 90A calculates a first light quantity P1 indicating the brightness of the first area 400A based on the shooting image signal indicating the captured image of the first area 400A (step S6). For example, the first processor 90A calculates the illuminance with the unit of lux as the first light quantity P1. Calculating the first light quantity P1 based on the shooting image signal indicating the captured image of the first area 400A is an example of obtaining first brightness information indicating the brightness of the first area 400A and is also an example of obtaining first brightness information indicating the brightness of the first area 400A based on a signal output from a sensor.

[0059] For example, in step S6, the first processor 90A calculates the average value of the gradation values of all pixels included in the captured image of the first area 400A, and based on a mathematical formula or table data indicating the relationship between the average value of the gradation values and the illuminance, obtains the illuminance corresponding to the calculated average value. The mathematical formula or table data indicating the relationship between the average value of the gradation values and the illuminance is pre-stored in the first storage device 80A.

[0060] Note that the first processor 90A may obtain the first light quantity P1 in a state where the first image 300A is not projected onto the first area 400A. In this case, before outputting a shooting command signal to the first camera 60A, the first processor 90A temporarily stops projecting the first image 300A onto the first area 400A by controlling the first optical device 40A.

[0061] Subsequently, the first processor 90A determines whether the first light quantity P1 is equal to or greater than the first threshold value Pth1 (step S7). For example, the first threshold value Pth1 is set to the value of the maximum illuminance of the image light L projected by one projector 1.

[0062] When the first light quantity P1 is equal to or greater than the first threshold value Pth1 (step S7: Yes), the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S8). After transmitting the first stack start signal to the second projector 1B, the first processor 90A ends the first determination process.

[0063] The first stack start signal is a signal for instructing the second projector 1B to stack a fourth image 310B, which is the same image as the first image 300A, on the first image 300A. When the first processor 90A determines that the first light quantity P1 is equal to or greater than the first threshold value Pth1, if the fourth image 310B has been stacked on the first image 300A by the second projector 1B, step S8 may be skipped.

[0064] On the one hand, when the first light quantity P1 is less than the first threshold value Pth1 (step S7: No), the first processor 90A transmits an end-of-stack signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S9). After transmitting the end-of-stack signal to the second projector 1B, the first processor 90A ends the first determination process.

[0065] The end-of-stack signal is a signal instructing the end of the stacking operation. When the first processor 90A determines that the first light quantity P1 is less than the first threshold value Pth1, if the fourth image 310B is not stacked on the first image 300A by the second projector 1B, step S9 may be skipped. The above is the description of the first determination process executed by the first processor 90A.

[0066] After the second processor 90B of the second projector 1B finishes the second initial process, when it receives an interrupt signal from the first projector 1A, it executes the first interrupt process. FIG. 8 is a flowchart showing the first interrupt process executed by the second processor 90B. The second processor 90B executes the first interrupt process shown in FIG. 8 by reading and executing a program from the second storage device 80B.

[0067] As shown in FIG. 8, when starting the first interrupt process, the second processor 90B first determines which interrupt signal, the first stack start signal or the end-of-stack signal, it has received (step S10).

[0068] When the second processor 90B receives the first stack start signal as an interrupt signal (step S10: first stack start signal), it controls the second driving device 30B to direct the projection direction Dp of the second projector 1B toward the center position of the first area 400A (step S11).

[0069] The second memory device 80B stores in advance a fourth yaw angle θ4 and a fourth pitch angle α4 for directing the projection direction Dp of the second projector 1B toward the center position of the first area 400A. In step S11, the second processor 90B controls the second drive device 30B so that the yaw angle θ and the pitch angle α of the second projector main body 10B match the fourth yaw angle θ4 and the fourth pitch angle α4, thereby directing the projection direction Dp of the second projector 1B toward the center position of the first area 400A.

[0070] Then, the second processor 90B controls the second optical device 40B based on the fourth video signal received from the video supply device 2 via the second communication device 70B, thereby projecting the same fourth image 310B as the first image 300A onto the first area 400A and stacking the fourth image 310B on the first image 300A in the first area 400A (step S12). After stacking the fourth image 310B on the first image 300A, the second processor 90B ends the first interrupt process.

[0071] The fourth image 310B is an image generated based on the fourth video signal. The fourth video signal is the same video signal as the first video signal. Therefore, the fourth image 310B is the same image as the first image 300A. Projecting the fourth image 310B onto the first area 400A means projecting image light L representing the same fourth image 310B as the first image 300A onto the first area 400A. When the image light L representing the fourth image 310B is projected onto the first area 400A, the same fourth image 310B as the first image 300A is stacked on the first image 300A in the first area 400A.

[0072] FIG. 9 is a diagram showing a state where the fourth image 310B is stacked on the first image 300A in the first region 400A. In the technical field of the present disclosure, displaying one image having high luminance on a projection surface by overlapping and projecting a plurality of the same images is called stack projection or stacking, etc. That is, in the present embodiment, the second projector 1B stacking the fourth image 310B on the first image 300A means that the second projector 1B overlaps and projects the fourth image 310B on the first image 300A, and as compared with projecting only the first image 300A by the first projector 1A, it is to display the first image 300A having high luminance in the first region 400A. Note that displaying the whole of one image by dividing one image into two or more parts and arranging and projecting each part by separate projectors is called tiling, etc. In tiling, the boundaries of adjacent parts may be overlapped, but the luminance of the overlapped part is reduced in accordance with the non-overlapped part. Thus, stack and tiling are different projection methods.

[0073] As shown in FIG. 9, the second projector 1B stacking the fourth image 310B on the first image 300A allows for misalignment between the first image 300A and the fourth image 310B stacked on the first image 300A. Since it is preferable to display the same image by overlapping it at the same position in stacking, the less misalignment, the better. The amount of such misalignment depends on the mechanical alignment accuracy of the driving device 30 of the projector 1. The mechanical alignment accuracy of the driving device 30 is the accuracy of matching the yaw angle θ and pitch angle α of the projector main body 10 to their target values. For example, in step S11, the second processor 90B controls the second driving device 30B so that the yaw angle θ and pitch angle α of the second projector main body 10B match the fourth yaw angle θ4 and fourth pitch angle α4. However, due to the alignment accuracy of the second driving device 30B, the yaw angle θ and pitch angle α of the second projector main body 10B may not completely match the target values of the fourth yaw angle θ4 and fourth pitch angle α4. In that case, the projection direction Dp of the second projector 1B is directed to a position different from the center position of the first region 400A. As a result, as shown in FIG. 9, misalignment occurs between the first image 300A and the fourth image 310B stacked on the first image 300A.

[0074] Note that the second processor 90B may perform distortion correction such as trapezoidal correction on the fourth image 310B generated by the second optical device 40B so that the rectangular fourth image 310B is stacked on the first image 300A in the first region 400A.

[0075] Hereinafter, the description will continue by referring back to FIG. 8. As shown in FIG. 8, when the second processor 90B receives a stack end signal as an interrupt signal (step S10: stack end signal), it controls the second driving device 30B to direct the projection direction Dp of the second projector 1B to the center position of the second region 400B (step S13).

[0076] In step S13, the second processor 90B controls the second driving device 30B so that the yaw angle θ and pitch angle α of the second projector main body 10B match the second yaw angle θ2 and the second pitch angle α2, thereby directing the projection direction Dp of the second projector 1B toward the center position of the second area 400B.

[0077] Then, based on the second video signal received from the video supply device 2 via the second communication device 70B, the second processor 90B controls the second optical device 40B to project the second image 300B onto the second area 400B (step S14). After the second processor 90B projects the second image 300B onto the second area 400B, it ends the first interrupt process. The above is the description of the first interrupt process executed by the second processor 90B.

[0078] By the first processor 90A executing the first initial process and the first determination process, and the second processor 90B executing the second initial process and the first interrupt process, the projection method of the first embodiment described below is realized.

[0079] The projection method of the first embodiment includes the following first to fourth steps. (First step) The first projector 1A projects the first image 300A onto the first area 400A. (Second step) The second projector 1B projects the second image 300B onto the second area 400B. (Third step) Obtain the first light quantity P1 indicating the brightness of the first area 400A. (Fourth step) When the first light quantity P1 satisfies the first condition, in the first area 400A, the second projector 1B stacks the fourth image 310B, which is the same as the first image 300A, on the first image 300A.

[0080] The first step is realized by the first processor 90A executing the first initial process. The second step is realized by the second processor 90B executing the second initial process. The third step is realized by the first processor 90A executing step S6 of the first determination process shown in FIG. 7. The fourth step is realized by the first processor 90A executing steps S7 and S8 of the first determination process shown in FIG. 7, and the second processor 90B executing steps S10 to S12 of the first interrupt process shown in FIG. 8. The first light quantity P1 is an example of first brightness information indicating the brightness of the first region 400A. Whether the first light quantity P1 is greater than or equal to the first threshold value Pth1 is an example of the first condition. The fact that the first light quantity P1 is greater than or equal to the first threshold value Pth1 is an example of the case where the first brightness information satisfies the first condition.

[0081] According to the above projection method, when the first light quantity P1 satisfies the first condition, the second projector 1B stacks the same fourth image 310B as the first image 300A on the first image 300A in the first region 400A. Therefore, according to the projection method of the first embodiment, even when the first light quantity P1 satisfies the first condition, an image can be projected onto the first region 400A. Also, when the first light quantity P1 does not satisfy the first condition, the second projector 1B continues to project the second image 300B onto the second region 400B. The first projector 1A projects the first image 300A onto the first region 400A regardless of whether the first light quantity P1 satisfies the first condition. Therefore, according to the projection method of the first embodiment, when the first light quantity P1 does not satisfy the first condition, the first image 300A and the second image 300B can be projected respectively.

[0082] In the projection method of the first embodiment, the fourth step includes the following fifth step. (Fifth step) When the first light quantity P1 is greater than or equal to the first threshold value Pth1, the second projector 1B stacks the fourth image 310B on the first image 300A in the first region 400A.

[0083] According to the above projection method, when the first light quantity P1 is equal to or greater than the first threshold value Pth1, the second projector 1B stacks the fourth image 310B on the first image 300A in the first area 400A. When the first light quantity P1 is equal to or greater than the first threshold value Pth1, compared with the case where the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected by the first projector 1A in the first area 400A is recognized by the viewer as an image with low brightness. In this case, by stacking the fourth image 310B, which is the same as the first image 300A, on the first image 300A, the brightness of the first image 300A displayed in the first area 400A can be doubled by simple calculation, so the visibility of the first image 300A can be improved.

[0084] In the projection method of the first embodiment, the fifth step includes the following sixth and seventh steps. (Sixth step) When the first light quantity P1 is equal to or greater than the first threshold value Pth1, the first projector 1A transmits a first stack start signal to the second projector 1B. (Seventh step) When the second projector 1B receives the first stack start signal, it stacks the fourth image 310B on the first image 300A in the first area 400A.

[0085] The sixth step is realized by the first processor 90A executing steps S7 and S8 of the first determination process shown in FIG. 7. The seventh step is realized by the second processor 90B executing steps S10 to S12 of the first interrupt process shown in FIG. 8. The first stack start signal is an example of the first signal.

[0086] According to the above projection method, when the first light quantity P1 is equal to or greater than the first threshold value Pth1, the first projector 1A can request the second projector 1B to stack the fourth image 310B on the first image 300A at an appropriate timing by transmitting a first stack start signal to the second projector 1B. Further, since the second projector 1B only needs to perform a stacking operation when it receives the first stack start signal, the processing load on the second projector 1B, that is, the processing load on the second processor 90B, can be reduced.

[0087] The projection method of the first embodiment further includes the following eighth and ninth steps. (Eighth step) After the fourth image 310B is stacked on the first image 300A, obtain a first light quantity P1 indicating the brightness of the first area 400A. (Ninth step) When the first light quantity P1 obtained in the eighth step is less than the first threshold value Pth1, the second projector 1B projects the second image 300B onto the second area 400B.

[0088] The eighth step is realized by the first processor 90A executing step S6 of the first determination process shown in FIG. 7 after the fourth image 310B is stacked on the first image 300A. The ninth step is realized by the first processor 90A executing steps S7 and S9 of the first determination process shown in FIG. 7 and the second processor 90B executing steps S10, S13, and S14 of the first interrupt process shown in FIG. 8 after the fourth image 310B is stacked on the first image 300A.

[0089] According to the above projection method, when the first light quantity P1 obtained after the fourth image 310B is stacked on the first image 300A is less than the first threshold value Pth1, that is, when it is not necessary to stack the fourth image 310B on the first image 300A, the second projector 1B projects the second image 300B onto the second area 400B again. Thereby, the display state of the image can be returned to a state where both the first image 300A and the second image 300B are displayed at an appropriate timing. Note that "after being stacked" means after the operation of stacking two or more images is completed, and can also be paraphrased as the period during which two or more images are stacked.

[0090] The projection system 100 of the first embodiment includes a first camera 60A that outputs a captured image signal indicating a captured image of the first area 400A, projects a first image 300A onto the first area 400A, and based on the captured image signal output from the first camera 60A, obtains a first light quantity P1 indicating the brightness of the first area 400A, and a first projector 1A that performs the above operations, and a second projector 1B that stacks the same fourth image 310B as the first image 300A on the first image 300A in the first area 400A when the first light quantity P1 satisfies the first condition. The first camera 60A is an example of a sensor that outputs a signal indicating the brightness of the first area 400A.

[0091] According to the above projection system 100, when the first light quantity P1 satisfies the first condition, the second projector 1B stacks the fourth image 310B on the first image 300A in the first area 400A. Therefore, according to the projection system 100 of the first embodiment, even when the first light quantity P1 satisfies the first condition, an image can be projected onto the first area 400A. Also, when the first light quantity P1 does not satisfy the first condition, the second projector 1B continues to project the second image 300B onto the second area 400B. The first projector 1A projects the first image 300A onto the first area 400A regardless of whether the first light quantity P1 satisfies the first condition. Therefore, according to the projection system 100 of the first embodiment, when the first light quantity P1 does not satisfy the first condition, the first image 300A and the second image 300B can be projected respectively.

[0092] The program of the first embodiment causes the computer to cause the first projector 1A to project the first image 300A onto the first area 400A, cause the second projector 1B to project the second image 300B onto a second area 400B different from the first area 400A, obtain the first light quantity P1 of the first area 400A, and when the first light quantity P1 satisfies the first condition, cause the second projector 1B to stack the fourth image 310B identical to the first image 300A on the first image 300A in the first area 400A.

[0093] According to the above program, when the first light quantity P1 satisfies the first condition, the second projector 1B stacks the fourth image 310B on the first image 300A in the first area 400A. Therefore, according to the above program, even when the first light quantity P1 satisfies the first condition, an image can be projected onto the first area 400A. Further, when the first light quantity P1 does not satisfy the first condition, the second projector 1B continues to project the second image 300B onto the second area 400B. The first projector 1A projects the first image 300A onto the first area 400A regardless of whether the first light quantity P1 satisfies the first condition. Therefore, according to the program of the first embodiment, when the first light quantity P1 does not satisfy the first condition, the first image 300A and the second image 300B can be projected respectively.

[0094] [Second Embodiment] Next, a second embodiment of the present disclosure will be described. In the second embodiment illustrated below, components common to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0095] FIG. 10 is a diagram schematically showing a projection system 200 according to the second embodiment. As shown in FIG. 10, the projection system 200 further includes a third projector 1C in addition to the first projector 1A, the second projector 1B, and the video supply device 2. The third projector 1C is connected to the second projector 1B via the third communication cable 5.

[0096] In the projection system 200, the video supply device 2 supplies a third video signal to the third projector 1C via the first projector 1A and the second projector 1B. The first projector 1A transmits the third video signal supplied from the video supply device 2 via the first communication cable 3 to the second projector 1B via the second communication cable 4. The second projector 1B transmits the third video signal transmitted from the first projector 1A to the third projector 1C via the third communication cable 5.

[0097] The third projector 1C projects a third image 300C onto a third area 400C different from the first area 400A and the second area 400B based on the third video signal supplied from the video supply device 2 via the first projector 1A and the second projector 1B. The third area 400C is an area included in a third projection surface such as a projection screen or a wall surface. The third projection surface may be the same projection surface as the first projection surface and the second projection surface, or may be a projection surface different from the first projection surface and the second projection surface.

[0098] The third image 300C may be the same image as the first image 300A or may be an image different from the first image 300A. In other words, the third video signal supplied to the third projector 1C may be the same video signal as the first video signal supplied to the first projector 1A or may be a video signal different from the first video signal.

[0099] Also, the third image 300C may be the same image as the second image 300B or may be an image different from the second image 300B. In other words, the third video signal supplied to the third projector 1C may be the same video signal as the second video signal supplied to the second projector 1B or may be a video signal different from the second video signal.

[0100] In addition, in FIG. 10, for convenience of explanation, an example is shown in which the first region 400A, the second region 400B, and the third region 400C are adjacent to each other in the horizontal direction. However, the positional relationship among the first region 400A, the second region 400B, and the third region 400C is not limited to the example shown in FIG. 10.

[0101] The configuration of the third projector 1C is the same as that of the first projector 1A and the second projector 1B. That is, the configuration of the third projector 1C is the same as the configuration of the projector 1 described in the first embodiment. Therefore, the description of the configuration of the third projector 1C is omitted.

[0102] Hereinafter, for convenience of explanation, the projector main body 10, the drive device 30, the optical device 40, the input device 50, the camera 60, the communication device 70, the storage device 80, and the processor 90 included in the third projector 1C may be referred to as the third projector main body 10C, the third drive device 30C, the third optical device 40C, the third input device 50C, the third camera 60C, the third communication device 70C, the third storage device 80C, and the third processor 90C.

[0103] Subsequently, the operation of the projection system 200 configured as described above will be described. In the following operation description, descriptions overlapping with the operation description of the first embodiment are appropriately omitted.

[0104] In the second embodiment, priorities are set for each of the first projector 1A, the second projector 1B, and the third projector 1C. In the second embodiment, the priorities are classified into the highest priority, the second priority, and the third priority. Hereinafter, the operation when the highest priority is set for the first projector 1A, the second priority is set for the second projector 1B, and the third priority is set for the third projector 1C will be described.

[0105] As described below, the first projector 1A with the highest priority always projects the first image 300A onto the first area 400A. The second projector 1B with the second priority preferentially projects the second image 300B onto the second area 400B as compared with the third projector 1C projecting the third image 300C onto the third area 400C. The third projector 1C with the third priority projecting the third image 300C onto the third area 400C has the lowest priority.

[0106] Similar to the first embodiment, when the first processor 90A of the first projector 1A receives a first operation to turn on the power of the first projector 1A via the first input device 50A, the first initial process is executed. Thereby, when the first operation is received, the first projector 1A projects the first image 300A onto the first area 400A.

[0107] Also, similar to the first embodiment, when the second processor 90B of the second projector 1B receives a second operation to turn on the power of the second projector 1B via the second input device 50B, the second initial process is executed. Thereby, when the second operation is received, the second projector 1B projects the second image 300B onto the second area 400B.

[0108] The third processor 90C of the third projector 1C executes the third initial process when it receives a third operation to turn on the power of the third projector 1C via the third input device 50C.

[0109] FIG. 11 is a flowchart showing the third initial process executed by the third processor 90C. When the third processor 90C receives the third operation, it reads and executes a program from the third storage device 80C to execute the third initial process shown in FIG. 11.

[0110] As shown in FIG. 11, when the third processor 90C starts the third initial process, it controls the third driving device 30C to direct the projection direction Dp of the third projector 1C toward the center position of the third area 400C (step S15).

[0111] The third storage device 80C stores in advance a third yaw angle θ3 and a third pitch angle α3 for directing the projection direction Dp of the third projector 1C toward the center position of the third area 400C. In step S15, the third processor 90C controls the third driving device 30C so that the yaw angle θ and the pitch angle α of the third projector main body 10C match the third yaw angle θ3 and the third pitch angle α3, thereby directing the projection direction Dp of the third projector 1C toward the center position of the third area 400C.

[0112] Note that when the third processor 90C starts the third initial process, if the projection direction Dp of the third projector 1C is already directed toward the center position of the third area 400C, step S15 may be skipped.

[0113] Then, the third processor 90C controls the third optical device 40C based on the third video signal received from the video supply device 2 via the third communication device 70C to project a third image 300C onto the third area 400C (step S16). After projecting the third image 300C onto the third area 400C, the third processor 90C ends the third initial process.

[0114] The third image 300C is an image generated based on the third video signal. Projecting the third image 300C onto the third area 400C means projecting image light L representing the third image 300C onto the third area 400C. When the image light L representing the third image 300C is projected onto the third area 400C, the third image 300C is displayed on the third area 400C.

[0115] As described above, when the third projector 1C receives the third operation, it projects the third image 300C onto the third area 400C. Note that the third processor 90C may perform distortion correction such as trapezoidal correction on the third image 300C generated by the third optical device 40C so that a rectangular third image 300C is displayed in the third area 400C. The above is the description of the third initial process executed by the third processor 90C.

[0116] After finishing the first initial process, the first processor 90A executes the second determination process at predetermined time intervals. FIG. 12 is a first flowchart showing the second determination process executed by the first processor 90A. FIG. 13 is a second flowchart showing the second determination process. The first processor 90A executes the second determination process shown in FIGS. 12 and 13 by reading and executing a program from the first storage device 80A.

[0117] As shown in FIG. 12, when starting the second determination process, the first processor 90A first calculates a first light quantity P1 indicating the brightness of the first area 400A based on a captured image signal indicating a captured image of the first area 400A (step S21). Specifically, in step S21, the first processor 90A outputs a capture command signal to the first camera 60A to acquire a captured image signal indicating a captured image of the first area 400A from the first camera 60A. The method for calculating the first light quantity P1 is as described in the first embodiment. Note that, as described in the first embodiment, the first light quantity P1 may be acquired in a state where the first image 300A is not projected onto the first area 400A.

[0118] Subsequently, the first processor 90A determines whether the first light quantity P1 is equal to or greater than a second threshold value Pth2 (step S22). For example, the second threshold value Pth2 is set to a value twice that of the first threshold value Pth1. That is, the second threshold value Pth2 is set to a value twice the maximum illuminance of the image light L projected by one projector 1. In this way, the second threshold value Pth2 is greater than the first threshold value Pth1.

[0119] When the first light quantity P1 is equal to or greater than the second threshold value Pth2 (step S22: Yes), the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S23).

[0120] Similar to the first embodiment, the first stack start signal is a signal for instructing the second projector 1B to stack the same fourth image 310B as the first image 300A on the first image 300A. When the first processor 90A determines that the first light quantity P1 is equal to or greater than the second threshold value Pth2, if the fourth image 310B has been stacked on the first image 300A by the second projector 1B, step S23 may be skipped.

[0121] Subsequently, the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S24). After transmitting the second stack start signal to the third projector 1C, the first processor 90A ends the second determination process.

[0122] The second stack start signal is a signal for instructing the third projector 1C to stack the same fifth image 310C as the first image 300A on the first image 300A. When the first processor 90A determines that the first light quantity P1 is equal to or greater than the second threshold value Pth2, if the fifth image 310C has been stacked on the first image 300A by the third projector 1C, step S24 may be skipped.

[0123] When the first light quantity P1 is less than the second threshold value Pth2 (step S22: No), the first processor 90A determines whether the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S25).

[0124] When the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S25: Yes), the first processor 90A detects the presence or absence of a person in the third monitoring area including the third area 400C based on a captured image signal indicating a captured image of the third monitoring area (step S26). For example, the third monitoring area includes an area having a radius of several meters on the projection plane centered on the center of the third area 400C.

[0125] Specifically, in step S26, the first processor 90A transmits an image request signal to the third projector 1C via the first communication device 70A. When the third processor 90C of the third projector 1C receives the image request signal via the third communication device 70C, the third processor 90C outputs a shooting command signal to the third camera 60C to obtain a captured image signal indicating a captured image of the third monitoring area from the third camera 60C. The third processor 90C transmits a captured image signal indicating a captured image of the third monitoring area to the first projector 1A via the third communication device 70C. As described above, the first processor 90A obtains a captured image of the third monitoring area. Note that since various methods such as an infrared sensor and image analysis are generally known as techniques for detecting a person present in the monitoring area, the description of a specific detection method is omitted.

[0126] Subsequently, the first processor 90A determines whether or not a person is present in the third monitoring area (step S27). For example, the first processor 90A determines that a person is present in the third monitoring area when the number of persons present in the third monitoring area is equal to or greater than a predetermined number. The predetermined number is an integer of 1 or more.

[0127] When a person is present in the third monitoring area (step S27: Yes), that is, when there is a person who may view the third image 300C, the first processor 90A detects the presence or absence of a person in the second monitoring area including the second area 400B based on a captured image signal indicating a captured image of the second monitoring area (step S28). For example, the second monitoring area includes an area having a radius of several meters on the projection plane centered on the center of the second area 400B.

[0128] Specifically, in step S28, the first processor 90A transmits an image request signal to the second projector 1B via the first communication device 70A. When the second processor 90B of the second projector 1B receives the image request signal via the second communication device 70B, it outputs a shooting command signal to the second camera 60B, thereby obtaining a shooting image signal indicating a captured image of the second monitoring area from the second camera 60B. The second processor 90B transmits a shooting image signal indicating a captured image of the second monitoring area to the first projector 1A via the second communication device 70B. Thus, the first processor 90A obtains a captured image of the second monitoring area.

[0129] Subsequently, the first processor 90A determines whether a person exists in the second monitoring area (step S29). For example, the first processor 90A determines that a person exists in the second monitoring area when the number of people existing in the second monitoring area is equal to or more than a predetermined number.

[0130] When the first processor 90A determines that a person exists in the second monitoring area (step S29: Yes), that is, when there is a person who may view the second image 300B, the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S30). After transmitting the second stack start signal to the third projector 1C, the first processor 90A ends the second determination process.

[0131] When the first processor 90A determines that a person exists in the second monitoring area, if the fifth image 310C is stacked on the first image 300A by the third projector 1C, step S30 may be skipped.

[0132] When there is no person in the second monitoring area (step S29: No), that is, when there is no person who may view the second image 300B, the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S31). After transmitting the first stack start signal to the second projector 1B, the first processor 90A ends the second determination process.

[0133] When the first processor 90A determines that there is no person in the second monitoring area, if the fourth image 310B is stacked on the first image 300A by the second projector 1B, step S31 may be skipped.

[0134] When there is no person in the third monitoring area (step S27: No), that is, when there is no person who may view the third image 300C, steps S28 and S29 are skipped and the process proceeds to step S30.

[0135] In step S25, when the first light quantity P1 is less than the first threshold value Pth1 (step S25: No), the first processor 90A proceeds to step S32 shown in FIG. 13.

[0136] As shown in FIG. 13, when the first processor 90A proceeds to step S32, it detects the presence or absence of a person in the second monitoring area based on a captured image signal indicating the captured image of the second monitoring area (step S32). Subsequently, the first processor 90A determines whether there is a person in the second monitoring area (step S33).

[0137] When there is a person in the second monitoring area (step S33: Yes), the first processor 90A calculates a second light quantity P2 indicating the brightness of the second area 400B based on a captured image signal indicating the captured image of the second area 400B (step S34).

[0138] Specifically, in step S34, the first processor 90A transmits an image request signal to the second projector 1B via the first communication device 70A. When the second processor 90B of the second projector 1B receives the image request signal via the second communication device 70B, it outputs a shooting command signal to the second camera 60B, thereby obtaining a shooting image signal indicating a shooting image of the second area 400B from the second camera 60B. The second processor 90B transmits a shooting image signal indicating the shooting image of the second area 400B to the first projector 1A via the second communication device 70B. Thus, the first processor 90A obtains the shooting image of the second area 400B. The method for calculating the second light quantity P2 is the same as the method for calculating the first light quantity P1.

[0139] Note that the second light quantity P2 may be obtained in a state where the second image 300B is not projected onto the second area 400B. In this case, before outputting a shooting command signal to the second camera 60B, the second processor 90B temporarily stops projecting the second image 300B onto the second area 400B by controlling the second optical device 40B.

[0140] Subsequently, the first processor 90A determines whether the second light quantity P2 is equal to or greater than the first threshold value Pth1 (step S35). When the second light quantity P2 is equal to or greater than the first threshold value Pth1 (step S35: Yes), the first processor 90A transmits a third stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S36). After transmitting the third stack start signal to the third projector 1C, the first processor 90A ends the second determination process.

[0141] The third stack start signal is a signal instructing the third projector 1C to stack the same sixth image 320C as the second image 300B on the second image 300B. When the first processor 90A determines that the second light quantity P2 is equal to or greater than the first threshold value Pth1, if the sixth image 320C is stacked on the second image 300B by the third projector 1C, step S36 may be skipped.

[0142] On the other hand, when the second light quantity P2 is less than the first threshold value Pth1 (step S35: No), the first processor 90A skips step S36 and ends the second determination process.

[0143] When no person exists in the second monitoring area (step S33: No), the first processor 90A detects the presence or absence of a person in the third monitoring area based on the captured image signal indicating the captured image of the third monitoring area (step S37). Subsequently, the first processor 90A determines whether a person exists in the third monitoring area (step S38).

[0144] When no person exists in the third monitoring area (step S38: No), the first processor 90A proceeds to the process of step S34. On the other hand, when a person exists in the third monitoring area (step S38: Yes), the first processor 90A calculates a third light quantity P3 indicating the brightness of the third area 400C based on the captured image signal indicating the captured image of the third area 400C (step S39).

[0145] Specifically, in step S39, the first processor 90A transmits an image request signal to the third projector 1C via the first communication device 70A. When the third processor 90C of the third projector 1C receives the image request signal via the third communication device 70C, it outputs a shooting command signal to the third camera 60C to obtain a captured image signal indicating the captured image of the third area 400C from the third camera 60C. The third processor 90C transmits the captured image signal indicating the captured image of the third area 400C to the first projector 1A via the third communication device 70C. As described above, the first processor 90A obtains the captured image of the third area 400C. The method for calculating the third light quantity P3 is the same as the method for calculating the first light quantity P1.

[0146] Note that the third light quantity P3 may be obtained in a state where the third image 300C is not projected onto the third region 400C. In this case, before outputting a shooting command signal to the third camera 60C, the third processor 90C temporarily stops projecting the third image 300C onto the third region 400C by controlling the third optical device 40C.

[0147] Subsequently, the first processor 90A determines whether the third light quantity P3 is equal to or greater than the first threshold value Pth1 (step S40). When the third light quantity P3 is equal to or greater than the first threshold value Pth1 (step S40: Yes), the first processor 90A transmits a fourth stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S41). After transmitting the fourth stack start signal to the second projector 1B, the first processor 90A ends the second determination process.

[0148] The fourth stack start signal is a signal that instructs the second projector 1B to stack the same seventh image 320B as the third image 300C on the third image 300C. When the first processor 90A determines that the third light quantity P3 is equal to or greater than the first threshold value Pth1, if the seventh image 320B is stacked on the third image 300C by the second projector 1B, step S41 may be skipped.

[0149] On the other hand, when the third light quantity P3 is less than the first threshold value Pth1 (step S40: No), the first processor 90A skips step S41 and ends the second determination process. The above is the description of the second determination process executed by the first processor 90A.

[0150] After at least one of the fourth image 310B and the fifth image 310C is stacked on the first image 300A, the first processor 90A executes a first release process. FIG. 14 is a first flowchart showing the first release process executed by the first processor 90A. FIG. 15 is a second flowchart showing the first release process. FIG. 16 is a third flowchart showing the first release process. The first processor 90A executes the first release process shown in FIGS. 14 to 16 by reading and executing a program from the first storage device 80A.

[0151] As shown in FIG. 14, when starting the first release process, the first processor 90A first determines the number of images stacked on the first image 300A (step S51). When the number of images stacked on the first image 300A is two (step S51: two), the first processor 90A calculates a fourth light quantity P4 indicating the brightness of the first area 400A based on a captured image signal indicating the captured image of the first area 400A (step S52).

[0152] When the number of images stacked on the first image 300A is two, both the fourth image 310B and the fifth image 310C are stacked on the first image 300A. The method of acquiring the captured image of the first area 400A is as described in the first embodiment. The method of calculating the fourth light quantity P4 is the same as the method of calculating the first light quantity P1.

[0153] The fourth light quantity P4 may be acquired in a state where the first image 300A, the fourth image 310B, and the fifth image 310C are not projected onto the first area 400A. In this case, before outputting a shooting command signal to the first camera 60A, the first processor 90A temporarily stops projecting the first image 300A onto the first area 400A by controlling the first optical device 40A. Further, the first processor 90A transmits a signal instructing to temporarily stop the projection of the fourth image 310B to the second projector 1B, and transmits a signal instructing to temporarily stop the projection of the fifth image 310C to the third projector 1C.

[0154] Subsequently, the first processor 90A determines whether the fourth light quantity P4 is greater than or equal to the second threshold value Pth2 (step S53). When the fourth light quantity P4 is greater than or equal to the second threshold value Pth2 (step S53: Yes), the first release process ends.

[0155] When the fourth light quantity P4 is less than the second threshold value Pth2 (step S53: No), the first processor 90A determines whether the fourth light quantity P4 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S54).

[0156] When the fourth light quantity P4 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S54: Yes), the first processor 90A transmits an end-of-stack signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S55). After transmitting the end-of-stack signal to the second projector 1B, the first processor 90A ends the first release process.

[0157] When the fourth light quantity P4 is less than the first threshold value Pth1 (step S54: No), the first processor 90A transmits an end-of-stack signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S56). Then, the first processor 90A transmits an end-of-stack signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S57). After transmitting the end-of-stack signal to the third projector 1C, the first processor 90A ends the first release process.

[0158] When the number of images stacked in the first image 300A is one (step S51: one), the first processor 90A proceeds to step S58 shown in FIG. 15.

[0159] As shown in FIG. 15, when the first processor 90A proceeds to step S58, it determines which of the fourth image 310B and the fifth image 310C is stacked in the first image 300A (step S58).

[0160] When the fifth image 310C is stacked on the first image 300A (step S58: fifth image), the first processor 90A calculates a fifth light quantity P5 indicating the brightness of the first area 400A based on a captured image signal indicating the captured image of the first area 400A (step S59).

[0161] The method of acquiring the captured image of the first area 400A is as described in the first embodiment. The method of calculating the fifth light quantity P5 is the same as the method of calculating the first light quantity P1. The fifth light quantity P5 may be acquired in a state where the first image 300A and the fifth image 310C are not projected onto the first area 400A. In this case, before outputting a capture command signal to the first camera 60A, the first processor 90A temporarily stops projecting the first image 300A onto the first area 400A by controlling the first optical device 40A. Further, the first processor 90A transmits a signal instructing to temporarily stop the projection of the fifth image 310C to the third projector 1C.

[0162] Subsequently, the first processor 90A determines whether the fifth light quantity P5 is equal to or greater than a second threshold value Pth2 (step S60). When the fifth light quantity P5 is equal to or greater than the second threshold value Pth2 (step S60: Yes), the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S61). After transmitting the first stack start signal to the second projector 1B, the first processor 90A ends the first release process.

[0163] When the fifth light quantity P5 is less than the second threshold value Pth2 (step S60: No), the first processor 90A determines whether the fifth light quantity P5 is equal to or greater than a first threshold value Pth1 and less than the second threshold value Pth2 (step S62).

[0164] When the fifth light quantity P5 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S62: Yes), the first processor 90A ends the first release process.

[0165] When the fifth light quantity P5 is less than the first threshold value Pth1 (step S62: No), the first processor 90A transmits an end-of-stack signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S63). After transmitting the end-of-stack signal to the third projector 1C, the first processor 90A ends the first release process.

[0166] When the fourth image 310B is stacked on the first image 300A (step S58: fourth image), the first processor 90A proceeds to step S64 shown in FIG. 16.

[0167] As shown in FIG. 16, when the first processor 90A proceeds to step S64, it calculates a sixth light quantity P6 indicating the brightness of the first area 400A based on a captured image signal indicating the captured image of the first area 400A (step S64).

[0168] The method of acquiring the captured image of the first area 400A is as described in the first embodiment. The method of calculating the sixth light quantity P6 is the same as the method of calculating the first light quantity P1. The sixth light quantity P6 may be acquired in a state where the first image 300A and the fourth image 310B are not projected onto the first area 400A. In this case, before outputting a capture command signal to the first camera 60A, the first processor 90A temporarily stops projecting the first image 300A onto the first area 400A by controlling the first optical device 40A. Further, the first processor 90A transmits a signal instructing to temporarily stop the projection of the fourth image 310B to the second projector 1B.

[0169] Subsequently, the first processor 90A determines whether the sixth light quantity P6 is greater than or equal to the second threshold value Pth2 (step S65). When the sixth light quantity P6 is greater than or equal to the second threshold value Pth2 (step S65: Yes), the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S66). After transmitting the second stack start signal to the third projector 1C, the first processor 90A ends the first release process.

[0170] When the sixth light quantity P6 is less than the second threshold value Pth2 (step S65: No), the first processor 90A determines whether the sixth light quantity P6 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S67).

[0171] When the sixth light quantity P6 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S67: Yes), the first processor 90A ends the first release process.

[0172] When the sixth light quantity P6 is less than the first threshold value Pth1 (step S67: No), the first processor 90A transmits a stack end signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S68). After transmitting the stack end signal to the second projector 1B, the first processor 90A ends the first release process. The above is the description of the first release process executed by the first processor 90A.

[0173] After the sixth image 320C is stacked on the second image 300B, the first processor 90A executes a second release process. FIG. 17 is a flowchart showing the second release process executed by the first processor 90A. The first processor 90A executes the second release process shown in FIG. 17 by reading and executing a program from the first storage device 80A.

[0174] As shown in FIG. 17, when the first processor 90A starts the second release process, first, based on a captured image signal indicating the captured image of the second area 400B, it calculates a seventh light quantity P7 indicating the brightness of the second area 400B (step S71). The method of acquiring the captured image of the second area 400B is as described in step S34 of the second determination process shown in FIG. 13. The method of calculating the seventh light quantity P7 is the same as the method of calculating the first light quantity P1.

[0175] Note that the seventh light quantity P7 may be acquired in a state where the second image 300B and the sixth image 320C are not projected onto the second area 400B. In this case, the first processor 90A transmits a signal instructing the second projector 1B to temporarily stop projecting the second image 300B, and transmits a signal instructing the third projector 1C to temporarily stop projecting the sixth image 320C.

[0176] Subsequently, the first processor 90A determines whether the seventh light quantity P7 is equal to or greater than a first threshold value Pth1 (step S72). When the seventh light quantity P7 is less than the first threshold value Pth1 (step S72: No), the first processor 90A transmits an end-of-stack signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S73). After transmitting the end-of-stack signal to the third projector 1C, the first processor 90A ends the second release process.

[0177] On the other hand, when the seventh light quantity P7 is equal to or greater than the first threshold value Pth1 (step S72: Yes), the first processor 90A skips step S73 and ends the second release process. The above is the description of the second release process executed by the first processor 90A.

[0178] After the seventh image 320B is stacked on the third image 300C, the first processor 90A executes a third release process. FIG. 18 is a flowchart showing the third release process executed by the first processor 90A. The first processor 90A executes the third release process shown in FIG. 18 by reading a program from the first storage device 80A and executing it.

[0179] As shown in FIG. 18, when the first processor 90A starts the third release process, first, based on the captured image of the third area 400C, it calculates the eighth light quantity P8 indicating the brightness of the third area 400C (step S81). The method of acquiring the captured image of the third area 400C is the same as that described in step S39 of the second determination process shown in FIG. 13. The method of calculating the eighth light quantity P8 is the same as the method of calculating the first light quantity P1.

[0180] Note that the eighth light quantity P8 may be acquired in a state where the third image 300C and the seventh image 320B are not projected onto the third area 400C. In this case, the first processor 90A transmits a signal instructing the second projector 1B to temporarily stop projecting the seventh image 320B and a signal instructing the third projector 1C to temporarily stop projecting the third image 300C.

[0181] Subsequently, the first processor 90A determines whether the eighth light quantity P8 is greater than or equal to the first threshold value Pth1 (step S82). When the eighth light quantity P8 is less than the first threshold value Pth1 (step S82: No), the first processor 90A transmits an end-of-stack signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S83). After the first processor 90A transmits the end-of-stack signal to the second projector 1B, it ends the third release process.

[0182] On the other hand, when the eighth light quantity P8 is greater than or equal to the first threshold value Pth1 (step S82: Yes), the first processor 90A skips step S83 and ends the third release process. The above is the description of the third release process executed by the first processor 90A.

[0183] Next, the second interrupt process executed by the second processor 90B will be described. After the second initial process is completed, when the second processor 90B receives an interrupt signal from the first projector 1A, it executes a second interrupt process. FIG. 19 is a flowchart showing the second interrupt process executed by the second processor 90B. The second processor 90B executes the second interrupt process shown in FIG. 19 by reading and executing a program from the second storage device 80B.

[0184] As shown in FIG. 19, when starting the second interrupt process, the second processor 90B first determines which interrupt signal among the first stack start signal, the fourth stack start signal, and the stack end signal has been received (step S91).

[0185] When the second processor 90B receives the first stack start signal as an interrupt signal (step S91: first stack start signal), it controls the second driving device 30B to direct the projection direction Dp of the second projector 1B toward the center position of the first area 400A (step S92).

[0186] Similar to the first embodiment, the second storage device 80B stores in advance a fourth yaw angle θ4 and a fourth pitch angle α4 for directing the projection direction Dp of the second projector 1B toward the center position of the first area 400A. In step S92, the second processor 90B controls the second driving device 30B so that the yaw angle θ and the pitch angle α of the second projector main body 10B coincide with the fourth yaw angle θ4 and the fourth pitch angle α4, thereby directing the projection direction Dp of the second projector 1B toward the center position of the first area 400A.

[0187] Then, based on the fourth video signal received from the video supply device 2 via the second communication device 70B, the second processor 90B controls the second optical device 40B to stack the same fourth image 310B as the first image 300A on the first image 300A in the first area 400A (step S93). After stacking the fourth image 310B on the first image 300A, the second processor 90B ends the second interrupt process.

[0188] When the second processor 90B receives the fourth stack start signal as an interrupt signal (step S91: fourth stack start signal), it controls the second drive device 30B to direct the projection direction Dp of the second projector 1B toward the center position of the third region 400C (step S94).

[0189] The second storage device 80B stores in advance a seventh yaw angle θ7 and a seventh pitch angle α7 for directing the projection direction Dp of the second projector 1B toward the center position of the third region 400C. In step S94, the second processor 90B controls the second drive device 30B so that the yaw angle θ and the pitch angle α of the second projector main body 10B match the seventh yaw angle θ7 and the seventh pitch angle α7, thereby directing the projection direction Dp of the second projector 1B toward the center position of the third region 400C.

[0190] Then, based on the seventh video signal received from the video supply device 2 via the second communication device 70B, the second processor 90B controls the second optical device 40B to project the seventh image 320B, which is the same as the third image 300C, onto the third region 400C and stack the seventh image 320B on the third image 300C in the third region 400C (step S95). After stacking the seventh image 320B on the third image 300C, the second processor 90B ends the second interrupt process.

[0191] The seventh image 320B is an image generated based on the seventh video signal. The seventh video signal is the same video signal as the third video signal. Therefore, the seventh image 320B is the same image as the third image 300C. Projecting the seventh image 320B onto the third region 400C means projecting the image light L representing the seventh image 320B onto the third region 400C. When the image light L representing the seventh image 320B is projected onto the third region 400C, the seventh image 320B, which is the same as the third image 300C, is stacked on the third image 300C in the third region 400C.

[0192] When the second processor 90B receives the stack end signal as an interrupt signal (step S91: stack end signal), it controls the second driving device 30B to direct the projection direction Dp of the second projector 1B toward the center position of the second area 400B (step S96).

[0193] Then, based on the second video signal received from the video supply device 2 via the second communication device 70B, the second processor 90B controls the second optical device 40B to project the second image 300B onto the second area 400B (step S97). After the second processor 90B projects the second image 300B onto the second area 400B, it ends the second interrupt process. The above is the description of the second interrupt process executed by the second processor 90B.

[0194] Next, the third interrupt process executed by the third processor 90C will be described. After finishing the third initial process, when the third processor 90C receives an interrupt signal from the first projector 1A, it executes the third interrupt process. FIG. 20 is a flowchart showing the third interrupt process executed by the third processor 90C. The third processor 90C executes the third interrupt process shown in FIG. 20 by reading and executing a program from the third storage device 80C.

[0195] As shown in FIG. 20, when starting the third interrupt process, the third processor 90C first determines which interrupt signal among the second stack start signal, the third stack start signal, and the stack end signal has been received (step S101).

[0196] When the third processor 90C receives the second stack start signal as an interrupt signal (step S101: second stack start signal), it controls the third driving device 30C to direct the projection direction Dp of the third projector 1C toward the center position of the first area 400A (step S102).

[0197] The third memory device 80C stores in advance a fifth yaw angle θ5 and a fifth pitch angle α5 for directing the projection direction Dp of the third projector 1C toward the center position of the first region 400A. In step S102, the third processor 90C controls the third drive device 30C so that the yaw angle θ and the pitch angle α of the third projector main body 10C match the fifth yaw angle θ5 and the fifth pitch angle α5, thereby directing the projection direction Dp of the third projector 1C toward the center position of the first region 400A.

[0198] Then, based on the fifth video signal received from the video supply device 2 via the third communication device 70C, the third processor 90C controls the third optical device 40C to project the same fifth image 310C as the first image 300A onto the first region 400A and stack the fifth image 310C on the first image 300A in the first region 400A (step S103). After stacking the fifth image 310C on the first image 300A, the third processor 90C ends the third interrupt process.

[0199] The fifth image 310C is an image generated based on the fifth video signal. The fifth video signal is the same video signal as the first video signal. Therefore, the fifth image 310C is the same image as the first image 300A. Projecting the fifth image 310C onto the first region 400A means projecting the image light L representing the fifth image 310C onto the first region 400A. When the image light L representing the fifth image 310C is projected onto the first region 400A, the same fifth image 310C as the first image 300A is stacked on the first image 300A in the first region 400A.

[0200] When the third processor 90C receives a third stack start signal as an interrupt signal (step S101: third stack start signal), it controls the third drive device 30C to direct the projection direction Dp of the third projector 1C toward the center position of the second region 400B (step S104).

[0201] The third memory device 80C stores in advance a sixth yaw angle θ6 and a sixth pitch angle α6 for directing the projection direction Dp of the third projector 1C toward the center position of the second region 400B. In step S104, the third processor 90C controls the third drive device 30C so that the yaw angle θ and the pitch angle α of the third projector main body 10C coincide with the sixth yaw angle θ6 and the sixth pitch angle α6, thereby directing the projection direction Dp of the third projector 1C toward the center position of the second region 400B.

[0202] Then, the third processor 90C controls the third optical device 40C based on the sixth video signal received from the video supply device 2 via the third communication device 70C, thereby projecting the same sixth image 320C as the second image 300B onto the second region 400B and stacking the sixth image 320C on the second image 300B in the second region 400B (step S105). After stacking the sixth image 320C on the second image 300B, the third processor 90C ends the third interrupt process.

[0203] The sixth image 320C is an image generated based on the sixth video signal. The sixth video signal is the same video signal as the second video signal. Therefore, the sixth image 320C is the same image as the second image 300B. Projecting the sixth image 320C onto the second region 400B means projecting the image light L representing the sixth image 320C onto the second region 400B. When the image light L representing the sixth image 320C is projected onto the second region 400B, the same sixth image 320C as the second image 300B is stacked on the second image 300B in the second region 400B.

[0204] When the third processor 90C receives a stack end signal as an interrupt signal (step S101: stack end signal), it controls the third drive device 30C to direct the projection direction Dp of the third projector 1C toward the center position of the third region 400C (step S106).

[0205] Then, the third processor 90C controls the third optical device 40C based on the third video signal received from the video supply device 2 via the third communication device 70C, and projects the third image 300C onto the third area 400C (step S107). After projecting the third image 300C onto the third area 400C, the third processor 90C ends the third interrupt process. The above is the description of the third interrupt process executed by the third processor 90C.

[0206] As described above, the first processor 90A executes the first initial process, the second determination process, the first release process, the second release process, and the third release process. The second processor 90B executes the second initial process and the second interrupt process. The third processor 90C executes the third initial process and the third interrupt process. Thereby, the projection method of the second embodiment described below is realized.

[0207] The projection method of the second embodiment includes the following first to sixth steps. (First step) The first projector 1A projects the first image 300A onto the first area 400A. (Second step) The second projector 1B projects the second image 300B onto the second area 400B. (Third step) The third projector 1C projects the third image 300C onto the third area 400C. (Fourth step) Obtain the first light quantity P1 indicating the brightness of the first area 400A. (Fifth step) When the first light quantity P1 is equal to or greater than the first threshold value Pth1, in the first area 400A, the second projector 1B stacks the fourth image 310B that is the same as the first image 300A on the first image 300A. (Sixth step) When the first light quantity P1 is equal to or greater than the second threshold value Pth2, in the first area 400A, the third projector 1C stacks the fifth image 310C that is the same as the first image 300A on the first image 300A and the fourth image 310B.

[0208] The first step is realized by the first processor 90A executing the first initial process. The second step is realized by the second processor 90B executing the second initial process. The third step is realized by the third processor 90C executing the third initial process. The fourth step is realized by the first processor 90A executing step S21 of the second determination process shown in FIG. 12. The fifth step is realized by the first processor 90A executing steps S22 and S23 of the second determination process shown in FIG. 12, and the second processor 90B executing steps S91 to S93 of the second interrupt process shown in FIG. 19. The sixth step is realized by the first processor 90A executing steps S22 and S24 of the second determination process shown in FIG. 12, and the third processor 90C executing steps S101 to S103 of the third interrupt process shown in FIG. 20.

[0209] According to the above projection method, when the first light quantity P1 is equal to or greater than the second threshold value Pth2, the fourth image 310B and the fifth image 310C are stacked on the first image 300A in the first region 400A. FIG. 21 is a diagram showing a state where the fourth image 310B and the fifth image 310C are stacked on the first image 300A in the first region 400A.

[0210] When the first light quantity P1 is equal to or greater than the second threshold value Pth2 that is greater than the first threshold value Pth1, compared with the case where the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected onto the first region 400A by the first projector 1A is recognized by the viewer as an image with very low brightness. In this case, by stacking the fourth image 310B and the fifth image 310C that are the same as the first image 300A on the first image 300A, the brightness of the first image 300A displayed in the first region 400A can be tripled by simple calculation, so the visibility of the first image 300A projected by the first projector 1A set to the highest priority can be improved.

[0211] In the projection method of the second embodiment, the sixth step includes the following seventh and eighth steps. (Step 7) When the first light quantity P1 is equal to or greater than the second threshold value Pth2, the first projector 1A transmits a second stack start signal to the third projector 1C. (Step 8) When the third projector 1C receives the second stack start signal, the third projector 1C stacks the fifth image 310C on the first image 300A in the first area 400A.

[0212] (Step 7) is realized by the first processor 90A executing steps S22 and S24 of the second determination process shown in FIG. 12. (Step 8) is realized by the third processor 90C executing steps S101 to S103 of the third interrupt process shown in FIG. 20. The second stack start signal is an example of the second signal.

[0213] According to the above projection method, when the first light quantity P1 is equal to or greater than the second threshold value Pth2, the first projector 1A can request the third projector 1C to stack the fifth image 310C on the first image 300A at an appropriate timing by transmitting the second stack start signal to the third projector 1C. Further, since the third projector 1C only needs to perform a stacking operation when it receives the second stack start signal, the processing load on the third projector 1C, that is, the processing load on the third processor 90C can be reduced.

[0214] The projection method of the second embodiment further includes the following steps 9 to 13. (Step 9) When the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, detect the presence or absence of a person in the third monitoring area including the third area 400C. (Step 10) When no person exists in the third monitoring area, the third projector 1C stacks the fifth image 310C on the first image 300A in the first area 400A. (Step 11) When a person exists in the third monitoring area, detect the presence or absence of a person in the second monitoring area including the second area 400B. (Step 12) When a person exists in the second monitoring area, the third projector 1C stacks the fifth image 310C on the first image 300A in the first area 400A. (Step 13) When no person exists in the second monitoring area, the second projector 1B stacks the fourth image 310B on the first image 300A in the first area 400A.

[0215] Steps 9 to 13 are realized by the first processor 90A executing steps S25 to S31 of the second determination process shown in FIG. 12, the second processor 90B executing steps S91 to S93 of the second interrupt process shown in FIG. 19, and the third processor 90C executing steps S101 to S103 of the third interrupt process shown in FIG. 20.

[0216] According to the above projection method, when the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, and no person exists in the third monitoring area, the fifth image 310C is stacked on the first image 300A in the first area 400A. FIG. 22 is a diagram showing a state where the fifth image 310C is stacked on the first image 300A in the first area 400A.

[0217] When the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, compared with the case where the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected onto the first area 400A by the first projector 1A is recognized by the viewer as an image with low luminance. On the other hand, since there is no person who may view the third image 300C, the necessity of projecting the third image 300C onto the third area 400C is low. Therefore, in this case, by stacking the fifth image 310C on the first image 300A by the third projector 1C set to the lowest third priority, the visibility of the first image 300A projected by the first projector 1A set to the highest priority can be improved. Also, in this case, the second projector 1B set to the second priority with a higher priority than the third projector 1C can continue to project the second image 300B onto the second area 400B.

[0218] Also, according to the above projection method, when the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, and there are persons in both the second monitoring area and the third monitoring area, the fifth image 310C is stacked on the first image 300A in the first area 400A.

[0219] In this case, since projecting the second image 300B by the second projector 1B set to the second priority is prioritized over projecting the third image 300C by the third projector 1C set to the third priority, the fifth image 310C is stacked on the first image 300A by the third projector 1C. Thereby, while the second projector 1B set to the second priority with a higher priority than the third projector 1C continues to project the second image 300B onto the second area 400B, the visibility of the first image 300A projected by the first projector 1A set to the highest priority can be improved.

[0220] Furthermore, according to the above projection method, when the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, a person exists in the third monitoring area, and no person exists in the second monitoring area, the fourth image 310B is stacked on the first image 300A in the first area 400A. FIG. 23 is a diagram showing a state where the fourth image 310B is stacked on the first image 300A in the first area 400A.

[0221] In this case, since there is no person who may view the second image 300B, the necessity of projecting the second image 300B onto the second area 400B is low. On the other hand, since there is a person who may view the third image 300C, the necessity of projecting the third image 300C onto the third area 400C is high. Therefore, in this case, projecting the third image 300C by the third projector 1C is prioritized over projecting the second image 300B by the second projector 1B. Thus, the second projector 1B stacks the fourth image 310B on the first image 300A. Thereby, while the third projector 1C continues to project the third image 300C onto the third area 400C, the visibility of the first image 300A projected by the first projector 1A set to the highest priority can be improved.

[0222] The projection method of the second embodiment further includes the following 14th to 21st steps. (14th step) When the first light quantity P1 is less than the first threshold value Pth1, detect the presence or absence of a person in the second monitoring area. (15th step) When a person exists in the second monitoring area, obtain a second light quantity P2 indicating the brightness of the second area 400B. (16th step) When the second light quantity P2 is equal to or greater than the first threshold value Pth1, in the second area 400B, the third projector 1C stacks the sixth image 320C identical to the second image 300B on the second image 300B. (17th step) When no person exists in the second monitoring area, detect the presence or absence of a person in the third monitoring area. When there is no person in the third monitoring area in the 18th process, the second light quantity P2 indicating the brightness of the second area 400B is obtained. When the second light quantity P2 is equal to or greater than the first threshold value Pth1 in the 19th process, the third projector 1C stacks the sixth image 320C on the second image 400B in the second area 400B. When there is a person in the third monitoring area in the 20th process, the third light quantity P3 indicating the brightness of the third area 400C is obtained. When the third light quantity P3 is equal to or greater than the first threshold value Pth1 in the 21st process, in the third area 400C, the second projector 1B stacks the seventh image 320B identical to the third image 300C on the third image 300C.

[0223] From the 14th process to the 21st process, the first processor 90A executes steps S32 to S41 of the second determination process shown in FIG. 13, the second processor 90B executes steps S91, S94, and S95 of the second interrupt process shown in FIG. 19, and the third processor 90C executes steps S101, S104, and S105 of the third interrupt process shown in FIG. 20. The second light quantity P2 is an example of the second brightness information. The third light quantity P3 is an example of the third brightness information.

[0224] According to the above projection method, when the first light quantity P1 is less than the first threshold value Pth1, there is a person in the second monitoring area, and the second light quantity P2 is equal to or greater than the first threshold value Pth1, the sixth image 320C is stacked on the second image 300B in the second area 400B. FIG. 24 is a diagram showing a state where the sixth image 320C is stacked on the second image 300B in the second area 400B.

[0225] When the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected onto the first area 400A by the first projector 1A is not recognized by the viewer as an image with low brightness. On the other hand, since there is a person who may view the second image 300B, it is highly necessary to project the second image 300B onto the second area 400B. Also, since the second light quantity P2 is greater than or equal to the first threshold value Pth1, the second image 300B projected onto the second area 400B is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the sixth image 320C on the second image 300B by the third projector 1C set to the lowest third priority, the visibility of the second image 300B projected by the second projector 1B set to the second priority can be improved.

[0226] Also, according to the above projection method, when the first light quantity P1 is less than the first threshold value Pth1, there are no people in both the second monitoring area and the third monitoring area, and the second light quantity P2 is greater than or equal to the first threshold value Pth1, the sixth image 320C is stacked on the second image 300B in the second area 400B.

[0227] When there are no people in both the second monitoring area and the third monitoring area, the necessity of projecting the second image 300B and the third image 300C is low. However, since the second light quantity P2 is greater than or equal to the first threshold value Pth1, when a viewer of the second image 300B appears, the second image 300B projected onto the second area 400B may be recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the sixth image 320C on the second image 300B by the third projector 1C set to the lowest third priority, when a viewer of the second image 300B appears, a highly visible second image 300B can be provided to the viewer.

[0228] Furthermore, according to the above projection method, when the first light quantity P1 is less than the first threshold value Pth1, there is no person in the second monitoring area, there is a person in the third monitoring area, and the third light quantity P3 is greater than or equal to the first threshold value Pth1, the seventh image 320B is stacked on the third image 300C in the third area 400C. FIG. 25 is a diagram showing a state where the seventh image 320B is stacked on the third image 300C in the third area 400C.

[0229] In this case, since there is no person who may view the second image 300B, the necessity of projecting the second image 300B onto the second area 400B is low. On the other hand, since there is a person who may view the third image 300C, the necessity of projecting the third image 300C onto the third area 400C is high. Therefore, in this case, projecting the third image 300C by the third projector 1C is prioritized over projecting the second image 300B by the second projector 1B. Also, since the third light quantity P3 is greater than or equal to the first threshold value Pth1, the third image 300C projected onto the third area 400C is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the seventh image 320B on the third image 300C by the second projector 1B, the visibility of the third image 300C projected by the third projector 1C can be improved.

[0230] The projection method of the second embodiment further includes the following twenty-second to twenty-fifth steps. (Twenty-second step) After both the fourth image 310B and the fifth image 310C are stacked on the first image 300A, the fourth light quantity P4 indicating the brightness of the first area 400A is obtained. (Twenty-third step) When the fourth light quantity P4 is less than the first threshold value Pth1, the second projector 1B projects the second image 300B onto the second area 400B. (Twenty-fourth step) When the fourth light quantity P4 is less than the first threshold value Pth1, the third projector 1C projects the third image 300C onto the third area 400C. In the case where the fourth light quantity P4 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 in the (25th process), the second projector 1B projects the second image 300B onto the second area 400B.

[0231] The 22nd process to the 25th process are realized by the first processor 90A executing steps S51 to S57 of the first release process shown in FIG. 14, the second processor 90B executing steps S91, S96, and S97 of the second interrupt process shown in FIG. 19, and the third processor 90C executing steps S101, S106, and S107 of the third interrupt process shown in FIG. 20. The fourth light quantity P4 is an example of the fourth brightness information.

[0232] When the fourth light quantity P4 obtained after both the fourth image 310B and the fifth image 310C are stacked on the first image 300A is less than the first threshold value Pth1, it is no longer necessary to stack both the fourth image 310B and the fifth image 310C on the first image 300A. Therefore, in this case, the second projector 1B projects the second image 300B onto the second area 400B again, and the third projector 1C projects the third image 300C onto the third area 400C again. Thereby, the display state of the images can be returned to the state where all of the first image 300A, the second image 300B, and the third image 300C are displayed at an appropriate timing.

[0233] Also, when the fourth light quantity P4 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, it is not necessary to stack one of the fourth image 310B and the fifth image 310C on the first image 300A. In this case, by the second projector 1B projecting the second image 300B onto the second area 400B again, the provision of the second image 300B by the second projector 1B set to the second priority with a higher priority than the third projector 1C can be resumed.

[0234] The projection method of the second embodiment further includes the following 26th process to 28th process. (Step 26) After the fifth image 310C out of the fourth image 310B and the fifth image 310C is stacked on the first image 300A, the fifth light quantity P5 indicating the brightness of the first region 400A is acquired. (Step 27) When the fifth light quantity P5 is less than the first threshold value Pth1, the third projector 1C projects the third image 300C onto the third region 400C. (Step 28) When the fifth light quantity P5 is greater than or equal to the second threshold value Pth2, the second projector 1B stacks the fourth image 310B on the first image 300A in the first region 400A.

[0235] Steps 26 to 28 are realized by the first processor 90A executing steps S58 to S63 of the first release process shown in FIG. 15, the second processor 90B executing steps S91 to S93 of the second interrupt process shown in FIG. 19, and the third processor 90C executing steps S101, S106, and S107 of the third interrupt process shown in FIG. 20. The fifth light quantity P5 is an example of the fifth brightness information.

[0236] When the fifth light quantity P5 acquired after the fifth image 310C out of the fourth image 310B and the fifth image 310C is stacked on the first image 300A is less than the first threshold value Pth1, there is no longer a need to stack the fifth image 310C on the first image 300A. Therefore, in this case, the third projector 1C projects the third image 300C onto the third region 400C again, so that the display state of the images can be returned to the state where all of the first image 300A, the second image 300B, and the third image 300C are displayed at an appropriate timing.

[0237] Also, when the fifth light quantity P5 obtained after the fifth image 310C among the fourth image 310B and the fifth image 310C is stacked on the first image 300A is equal to or greater than the second threshold value Pth2, stacking only the fifth image 310C on the first image 300A cannot sufficiently improve the luminance of the first image 300A. Therefore, in this case, by stacking the fourth image 310B on the first image 300A by the second projector 1B, the visibility of the first image 300A projected by the first projector 1A can be improved.

[0238] The projection method of the second embodiment further includes the following 29th to 31st steps. (29th step) After the fourth image 310B among the fourth image 310B and the fifth image 310C is stacked on the first image 300A, the sixth light quantity P6 indicating the brightness of the first region 400A is acquired. (30th step) When the sixth light quantity P6 is less than the first threshold value Pth1, the second projector 1B projects the second image 300B onto the second region 400B. (31st step) When the sixth light quantity P6 is equal to or greater than the second threshold value Pth2, the third projector 1C stacks the fifth image 310C on the first image 300A in the first region 400A.

[0239] The 29th to 31st steps are realized by the first processor 90A executing steps S64 to S68 of the first release process shown in FIG. 16, the second processor 90B executing steps S91, S96, and S97 of the second interrupt process shown in FIG. 19, and the third processor 90C executing steps S101 to S103 of the third interrupt process shown in FIG. 20. The sixth light quantity P6 is an example of the sixth brightness information.

[0240] When the sixth light quantity P6 obtained after the fourth image 310B among the fourth image 310B and the fifth image 310C is stacked on the first image 300A is less than the first threshold value Pth1, there is no longer a need to stack the fourth image 310B on the first image 300A. Therefore, in this case, the second projector 1B projects the second image 300B onto the second area 400B again, so that the display state of the image can be returned to a state where all of the first image 300A, the second image 300B, and the third image 300C are displayed at an appropriate timing.

[0241] Also, when the sixth light quantity P6 obtained after the fourth image 310B among the fourth image 310B and the fifth image 310C is stacked on the first image 300A is greater than or equal to the second threshold value Pth2, the luminance of the first image 300A cannot be sufficiently improved only by stacking the fourth image 310B on the first image 300A. Therefore, in this case, by stacking the fifth image 310C on the first image 300A by the third projector 1C, the visibility of the first image 300A projected by the first projector 1A can be improved.

[0242] The projection method of the second embodiment further includes the following 32nd step and 33rd step. (32nd step) After the sixth image 320C is stacked on the second image 300B, the seventh light quantity P7 indicating the brightness of the second area 400B is obtained. (33rd step) When the seventh light quantity P7 is less than the first threshold value Pth1, the third projector 1C projects the third image 300C onto the third area 400C.

[0243] The 32nd step and the 33rd step are realized by the first processor 90A executing the second release process shown in FIG. 17 and the third processor 90C executing steps S101, S106, and S107 of the third interrupt process shown in FIG. 20. The seventh light quantity P7 is an example of the seventh brightness information.

[0244] When the seventh light quantity P7 obtained after the sixth image 320C is stacked on the second image 300B is less than the first threshold value Pth1, it is no longer necessary to stack the sixth image 320C on the second image 300B. Therefore, in this case, the third projector 1C projects the third image 300C onto the third area 400C again, so that the display state of the image can be returned to the state where all of the first image 300A, the second image 300B, and the third image 300C are displayed at an appropriate timing.

[0245] The projection method of the second embodiment further includes the following 34th step and 35th step. (34th step) After the seventh image 320B is stacked on the third image 300C, an eighth light quantity P8 indicating the brightness of the third area 400C is obtained. (35th step) When the eighth light quantity P8 is less than the first threshold value, the second projector 1B projects the second image 300B onto the second area 400B.

[0246] The 34th step and the 35th step are realized by the first processor 90A executing the eighth release process shown in FIG. 18 and the second processor 90B executing steps S91, S96, and S97 of the second interrupt process shown in FIG. 19. The eighth light quantity P8 is an example of the eighth brightness information.

[0247] When the eighth light quantity P8 obtained after the seventh image 320B is stacked on the third image 300C is less than the first threshold value Pth1, it is no longer necessary to stack the seventh image 320B on the third image 300C. Therefore, in this case, the second projector 1B projects the second image 300B onto the second area 400B again, so that the display state of the image can be returned to the state where all of the first image 300A, the second image 300B, and the third image 300C are displayed at an appropriate timing.

[0248] [Third Embodiment] Next, a third embodiment of the present disclosure will be described. The projection system of the third embodiment is the same as the projection system 200 of the second embodiment. Therefore, in the third embodiment exemplified below, for the components common to the second embodiment, the same reference numerals as those used in the second embodiment are assigned, and detailed descriptions are omitted as appropriate.

[0249] Hereinafter, the operations of the first projector 1A, the second projector 1B, and the third projector 1C in the third embodiment will be described. In the following operation descriptions, descriptions overlapping with those of the second embodiment are omitted as appropriate.

[0250] Note that in the third embodiment as well, priorities are set for each of the first projector 1A, the second projector 1B, and the third projector 1C. In the third embodiment, the priorities are classified into a first priority, a second priority, and a third priority. Hereinafter, the operations when the first priority is set for the first projector 1A, the second priority is set for the second projector 1B, and the third priority is set for the third projector 1C will be described.

[0251] As described below, the first projector 1A with the first priority set preferentially projects the first image 300A onto the first area 400A as compared with the second projector 1B projecting the second image 300B onto the second area 400B. The second projector 1B with the second priority set preferentially projects the second image 300B onto the second area 400B as compared with the third projector 1C projecting the third image 300C onto the third area 400C. The third projector 1C with the third priority set projecting the third image 300C onto the third area 400C has the lowest priority.

[0252] Similar to the second embodiment, when the first processor 90A of the first projector 1A receives a first operation to turn on the power of the first projector 1A via the first input device 50A, the first initial process is executed. As a result, when the first operation is received, the first projector 1A projects the first image 300A onto the first area 400A.

[0253] Similar to the second embodiment, when the second processor 90B of the second projector 1B receives a second operation to turn on the power of the second projector 1B via the second input device 50B, the second initial process is executed. As a result, when the second operation is received, the second projector 1B projects the second image 300B onto the second area 400B.

[0254] Similar to the second embodiment, when the third processor 90C of the third projector 1C receives a third operation to turn on the power of the third projector 1C via the third input device 50C, the third initial process is executed. As a result, when the third operation is received, the third projector 1C projects the third image 300C onto the third area 400C.

[0255] After finishing the first initial process, the first processor 90A of the first projector 1A executes the third determination process at a predetermined time interval. FIG. 26 is a first flowchart showing the third determination process executed by the first processor 90A. FIG. 27 is a second flowchart showing the third determination process. FIG. 28 is a third flowchart showing the third determination process. FIG. 29 is a fourth flowchart showing the third determination process. FIG. 30 is a fifth flowchart showing the third determination process. FIG. 31 is a sixth flowchart showing the third determination process. FIG. 32 is a seventh flowchart showing the third determination process. The first processor 90A executes the third determination process shown in FIGS. 26 to 32 by reading and executing a program from the first storage device 80A.

[0256] As shown in FIG. 26, when the first processor 90A starts the third determination process, first, based on a captured image signal indicating a captured image of the first monitoring area including the first area 400A, it detects the presence or absence of a person in the first monitoring area (step S111). For example, the first monitoring area includes an area centered on the center of the first area 400A and having a radius of several meters on the projection plane. In step S111, the first processor 90A outputs a capture command signal to the first camera 60A to obtain a captured image signal indicating a captured image of the first monitoring area from the first camera 60A.

[0257] Subsequently, the first processor 90A determines whether a person exists in the first monitoring area (step S112). If a person exists in the first monitoring area (step S112: Yes), that is, if there is a person who may view the first image 300A, the process proceeds to step S113.

[0258] On the other hand, if no person exists in the first monitoring area (step S112: No), that is, if there is no person who may view the first image 300A, the process proceeds to step S134 shown in FIG. 29. Each step shown in FIG. 29 will be described later.

[0259] When the first processor 90A proceeds to step S113, based on a captured image signal indicating a captured image of the first area 400A, it calculates a first light quantity P1 indicating the brightness of the first area 400A (step S113). Subsequently, the first processor 90A determines whether the first light quantity P1 is greater than or equal to a second threshold value Pth2 (step S114).

[0260] If the first light quantity P1 is greater than or equal to the second threshold value Pth2 (step S114: Yes), the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S115).

[0261] When the first processor 90A determines that the first light quantity P1 is equal to or greater than the second threshold value Pth2, if the fourth image 310B is stacked on the first image 300A by the second projector 1B, step S115 may be skipped.

[0262] Subsequently, the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S116). After transmitting the second stack start signal to the third projector 1C, the first processor 90A ends the third determination process.

[0263] When the first processor 90A determines that the first light quantity P1 is equal to or greater than the second threshold value Pth2, if the fifth image 310C is stacked on the first image 300A by the third projector 1C, step S116 may be skipped.

[0264] When the first light quantity P1 of the first processor 90A is less than the second threshold value Pth2 (step S114: No), it proceeds to step S117 shown in FIG. 27. As shown in FIG. 27, when the first processor 90A proceeds to step S117, it determines whether the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S117).

[0265] When the first light quantity P1 of the first processor 90A is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S117: Yes), it proceeds to step S118. On the other hand, when the first light quantity P1 of the first processor 90A is less than the first threshold value Pth1 (step S117: No), it proceeds to step S124 shown in FIG. 28. Each step shown in FIG. 28 will be described later.

[0266] When the first processor 90A transitions to step S118, it detects the presence or absence of a person in the third monitoring area based on a captured image signal indicating the captured image of the third monitoring area (step S118). Subsequently, the first processor 90A determines whether a person exists in the third monitoring area (step S119). The method by which the first processor 90A acquires the captured image of the third monitoring area is as described in the second embodiment.

[0267] When a person exists in the third monitoring area (step S119: Yes), the first processor 90A detects the presence or absence of a person in the second monitoring area based on a captured image signal indicating the captured image of the second monitoring area (step S120). Subsequently, the first processor 90A determines whether a person exists in the second monitoring area (step S121). The method by which the first processor 90A acquires the captured image of the second monitoring area is as described in the second embodiment.

[0268] When a person exists in the second monitoring area (step S121: Yes), the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S122). After the first processor 90A transmits the second stack start signal to the third projector 1C, it ends the third determination process.

[0269] When the first processor 90A determines that a person exists in the second monitoring area, if the fifth image 310C is stacked on the first image 300A by the third projector 1C, step S122 may be skipped.

[0270] When a person does not exist in the second monitoring area (step S121: No), the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S123). After the first processor 90A transmits the first stack start signal to the second projector 1B, it ends the third determination process.

[0271] When the first processor 90A determines that there is no person in the second monitoring area, if the fourth image 310B is stacked on the first image 300A by the second projector 1B, step S123 may be skipped.

[0272] When the first processor 90A determines that there is no person in the third monitoring area (step S119: No), it skips steps S120 and S121 and proceeds to step S122.

[0273] As already described, when the first light quantity P1 is less than the first threshold value Pth1 (step S117: No), the first processor 90A proceeds to step S124 shown in FIG. 28. As shown in FIG. 28, when the first processor 90A proceeds to step S124, it detects the presence or absence of a person in the second monitoring area based on a captured image signal indicating the captured image of the second monitoring area (step S124).

[0274] Subsequently, the first processor 90A determines whether there is a person in the second monitoring area (step S125). When the first processor 90A determines that there is a person in the second monitoring area (step S125: Yes), it calculates a second light quantity P2 indicating the brightness of the second area 400B based on a captured image signal indicating the captured image of the second area 400B (step S126). The method by which the first processor 90A acquires the captured image of the second area 400B is as described in the second embodiment.

[0275] Subsequently, the first processor 90A determines whether the second light quantity P2 is greater than or equal to the first threshold value Pth1 (step S127). When the first processor 90A determines that the second light quantity P2 is greater than or equal to the first threshold value Pth1 (step S127: Yes), it transmits a third stack start signal to the third projector 1C via the first communication device 70A as an interrupt signal (step S128). After the first processor 90A transmits the third stack start signal to the third projector 1C, it ends the third determination process.

[0276] When the first processor 90A determines that the second light quantity P2 is equal to or greater than the first threshold value Pth1, if the sixth image 320C is stacked on the second image 300B by the third projector 1C, step S128 may be skipped.

[0277] On the other hand, when the second light quantity P2 is less than the first threshold value Pth1 (step S127: No), the first processor 90A skips step S128 and ends the third determination process.

[0278] When no person exists in the second monitoring area (step S125: No), the first processor 90A detects the presence or absence of a person in the third monitoring area based on the captured image signal indicating the captured image of the third monitoring area (step S129). Then, the first processor 90A determines whether a person exists in the third monitoring area (step S130).

[0279] When a person exists in the third monitoring area (step S130: Yes), the first processor 90A proceeds to step S131. On the other hand, when no person exists in the third monitoring area (step S130: No), the first processor 90A proceeds to step S158 shown in FIG. 32. Each step shown in FIG. 32 will be described later.

[0280] When the first processor 90A proceeds to step S131, it calculates a third light quantity P3 indicating the brightness of the third area 400C based on the captured image signal indicating the captured image of the third area 400C (step S131). The method by which the first processor 90A acquires the captured image of the third area 400C is as described in the second embodiment.

[0281] Subsequently, the first processor 90A determines whether the third light quantity P3 is greater than or equal to the first threshold value Pth1 (step S132). When the third light quantity P3 is greater than or equal to the first threshold value Pth1 (step S132: Yes), the first processor 90A transmits a fourth stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S133). After transmitting the fourth stack start signal to the second projector 1B, the first processor 90A ends the third determination process.

[0282] When the first processor 90A determines that the third light quantity P3 is greater than or equal to the first threshold value Pth1, if the seventh image 320B is stacked on the third image 300C by the second projector 1B, step S133 may be skipped.

[0283] On the other hand, when the third light quantity P3 is less than the first threshold value Pth1 (step S132: No), the first processor 90A skips step S133 and ends the third determination process.

[0284] As already described, when there is no person in the first monitoring area (step S112: No), the first processor 90A proceeds to step S134 shown in FIG. 29. As shown in FIG. 29, when the first processor 90A proceeds to step S134, based on the captured image signal indicating the captured image of the second monitoring area, it detects the presence or absence of a person in the second monitoring area (step S134).

[0285] Then, the first processor 90A determines whether there is a person in the second monitoring area (step S135). When there is a person in the second monitoring area (step S135: Yes), the first processor 90A proceeds to step S136. On the other hand, when there is no person in the second monitoring area (step S135: No), the first processor 90A proceeds to step S150 shown in FIG. 31. Each step shown in FIG. 31 will be described later.

[0286] When the first processor 90A transitions to step S136, it calculates a second light quantity P2 indicating the brightness of the second region 400B based on a captured image signal indicating the captured image of the second region 400B (step S136).

[0287] Then, the first processor 90A determines whether the second light quantity P2 is greater than or equal to a second threshold value Pth2 (step S137). When the second light quantity P2 is greater than or equal to the second threshold value Pth2 (step S137: Yes), the first processor 90A transmits a third stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S138).

[0288] When the first processor 90A determines that the second light quantity P2 is greater than or equal to the second threshold value Pth2, if the sixth image 320C is stacked on the second image 300B by the third projector 1C, step S138 may be skipped.

[0289] Subsequently, the first processor 90A controls the first driving device 30A and the first optical device 40A to stack an eighth image 310A identical to the second image 300B on the second image 300B in the second region 400B (step S139). After stacking the eighth image 310A on the second image 300B, the first processor 90A ends the third determination process.

[0290] Specifically, in step S139, the first processor 90A controls the first driving device 30A to direct the projection direction Dp of the first projector 1A toward the center position of the second region 400B.

[0291] The first memory device 80A stores in advance an eighth yaw angle θ8 and an eighth pitch angle α8 for directing the projection direction Dp of the first projector 1A toward the center position of the second region 400B. In step S139, the first processor 90A controls the first driving device 30A so that the yaw angle θ and the pitch angle α of the first projector main body 10A match the eighth yaw angle θ8 and the eighth pitch angle α8, thereby directing the projection direction Dp of the first projector 1A toward the center position of the second region 400B.

[0292] Then, in step S139, the first processor 90A controls the first optical device 40A based on the eighth video signal received from the video supply device 2 via the first communication device 70A, thereby projecting the eighth image 310A onto the second region 400B and stacking the eighth image 310A on the second image 300B in the second region 400B.

[0293] The eighth image 310A is an image generated based on the eighth video signal. The eighth video signal is the same video signal as the second video signal. Therefore, the eighth image 310A is the same image as the second image 300B. Projecting the eighth image 310A onto the second region 400B means projecting the image light L representing the eighth image 310A onto the second region 400B. When the image light L representing the eighth image 310A is projected onto the second region 400B, the same eighth image 310A as the second image 300B is stacked on the second image 300B in the second region 400B.

[0294] Note that the first processor 90A may perform distortion correction such as trapezoidal correction on the eighth image 310A generated by the first optical device 40A so that a rectangular eighth image 310A is displayed in the second region 400B. When the first processor 90A determines that the second light quantity P2 is equal to or greater than the second threshold value Pth2 and the eighth image 310A is stacked on the second image 300B by the first projector 1A, the first processor 90A may skip step S139.

[0295] When the second light quantity P2 is less than the second threshold value Pth2 (step S137: No), the first processor 90A determines whether the second light quantity P2 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S140).

[0296] When the second light quantity P2 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S140: Yes), the first processor 90A detects the presence or absence of a person in the third monitoring area based on the captured image signal indicating the captured image of the third monitoring area (step S141). Then, the first processor 90A determines whether a person exists in the third monitoring area (step S142).

[0297] When a person exists in the third monitoring area (step S142: Yes), the first processor 90A controls the first driving device 30A and the first optical device 40A to stack the eighth image 310A on the second image 300B in the second area 400B (step S143). After stacking the eighth image 310A on the second image 300B, the first processor 90A ends the third determination process.

[0298] When the first processor 90A determines that a person exists in the third monitoring area and the eighth image 310A is stacked on the second image 300B by the first projector 1A, step S143 may be skipped.

[0299] When no person exists in the third monitoring area (step S142: No), the first processor 90A transmits a third stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S144). After transmitting the third stack start signal to the third projector 1C, the first processor 90A ends the third determination process.

[0300] When the first processor 90A determines that there is no person in the third monitoring area, if the sixth image 320C is stacked on the second image 300B by the third projector 1C, step S144 may be skipped.

[0301] When the second light quantity P2 is less than the first threshold value Pth1 (step S140: No), the first processor 90A proceeds to step S145 shown in FIG. 30. As shown in FIG. 30, when the first processor 90A proceeds to step S145, it detects the presence or absence of a person in the third monitoring area based on the captured image signal indicating the captured image of the third monitoring area (step S145). Then, the first processor 90A determines whether or not there is a person in the third monitoring area (step S146).

[0302] When the first processor 90A determines that there is a person in the third monitoring area (step S146: Yes), it proceeds to step S147. On the other hand, when the first processor 90A determines that there is no person in the third monitoring area (step S146: No), it proceeds to step S158 shown in FIG. 32. Each step shown in FIG. 32 will be described later.

[0303] When the first processor 90A proceeds to step S147, it calculates a third light quantity P3 indicating the brightness of the third area 400C based on the captured image signal indicating the captured image of the third area 400C (step S147). Then, the first processor 90A determines whether or not the third light quantity P3 is greater than or equal to the first threshold value Pth1 (step S148).

[0304] When the third light quantity P3 is greater than or equal to the first threshold value Pth1 (step S148: Yes), the first processor 90A controls the first driving device 30A and the first optical device 40A to stack the same ninth image 320A as the third image 300C on the third image 300C in the third area 400C (step S149). After the first processor 90A stacks the ninth image 320A on the third image 300C, it ends the third determination process.

[0305] Specifically, in step S149, the first processor 90A controls the first driving device 30A to direct the projection direction Dp of the first projector 1A toward the center position of the third area 400C.

[0306] The first storage device 80A stores in advance a ninth yaw angle θ9 and a ninth pitch angle α9 for directing the projection direction Dp of the first projector 1A toward the center position of the third area 400C. In step S149, the first processor 90A controls the first driving device 30A so that the yaw angle θ and the pitch angle α of the first projector main body 10A match the ninth yaw angle θ9 and the ninth pitch angle α9, thereby directing the projection direction Dp of the first projector 1A toward the center position of the third area 400C.

[0307] Then, in step S149, the first processor 90A controls the first optical device 40A based on the ninth video signal received from the video supply device 2 via the first communication device 70A, projects the ninth image 320A onto the third area 400C, and stacks the ninth image 320A on the third image 300C in the third area 400C.

[0308] The ninth image 320A is an image generated based on the ninth video signal. The ninth video signal is the same video signal as the third video signal. Therefore, the ninth image 320A is the same image as the third image 300C. Projecting the ninth image 320A onto the third area 400C means projecting the image light L representing the ninth image 320A onto the third area 400C. When the image light L representing the ninth image 320A is projected onto the third area 400C, the same ninth image 320A as the third image 300C is stacked on the third image 300C in the third area 400C.

[0309] Note that the first processor 90A may perform distortion correction such as trapezoidal correction on the ninth image 320A generated by the first optical device 40A so that the rectangular ninth image 320A is displayed in the third region 400C. When the first processor 90A determines that the third light quantity P3 is equal to or greater than the first threshold value Pth1, if the ninth image 320A is stacked on the third image 300C by the first projector 1A, step S149 may be skipped.

[0310] When the third light quantity P3 is less than the first threshold value Pth1 (step S148: No), the first processor 90A skips step S149 and ends the third determination process.

[0311] As already described, when no person exists in the second monitoring area (step S135: No), the first processor 90A proceeds to step S150 shown in FIG. 31. As shown in FIG. 31, when the first processor 90A proceeds to step S150, it detects the presence or absence of a person in the third monitoring area based on a captured image signal indicating the captured image of the third monitoring area (step S150).

[0312] Then, the first processor 90A determines whether a person exists in the third monitoring area (step S151). When a person exists in the third monitoring area (step S151: Yes), the first processor 90A proceeds to step S152. On the other hand, when no person exists in the third monitoring area (step S151: No), the first processor 90A proceeds to step S158 shown in FIG. 32. Each step shown in FIG. 32 will be described later.

[0313] When the first processor 90A proceeds to step S152, it calculates a third light quantity P3 indicating the brightness of the third region 400C based on a captured image signal indicating the captured image of the third region 400C (step S152). Then, the first processor 90A determines whether the third light quantity P3 is equal to or greater than the second threshold value Pth2 (step S153).

[0314] When the third light quantity P3 is equal to or greater than the second threshold value Pth2 (step S153: Yes), the first processor 90A transmits a fourth stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S154). When the first processor 90A determines that the third light quantity P3 is equal to or greater than the second threshold value Pth2, if the seventh image 320B is stacked on the third image 300C by the second projector 1B, step S154 may be skipped.

[0315] Then, the first processor 90A controls the first driving device 30A and the first optical device 40A to stack the ninth image 320A on the third image 300C in the third region 400C (step S140). After stacking the ninth image 320A on the third image 300C, the first processor 90A ends the third determination process.

[0316] When the first processor 90A determines that the third light quantity P3 is equal to or greater than the second threshold value Pth2, if the ninth image 320A is stacked on the third image 300C by the first projector 1A, step S155 may be skipped.

[0317] When the third light quantity P3 is less than the second threshold value Pth2 (step S153: No), the first processor 90A determines whether the third light quantity P3 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S156).

[0318] When the third light quantity P3 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S156: Yes), the first processor 90A transmits a fourth stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S157). After transmitting the fourth stack start signal to the second projector 1B, the first processor 90A ends the third determination process.

[0319] When the first processor 90A determines that the third light quantity P3 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, if the seventh image 320B is stacked on the third image 300C by the second projector 1B, step S157 may be skipped.

[0320] When the third light quantity P3 is less than the first threshold value Pth1 (step S156: No), the first processor 90A skips step S157 and ends the third determination process.

[0321] As shown in FIG. 32, when the first processor 90A proceeds to step S158, it calculates a first light quantity P1 indicating the brightness of the first area 400A based on a captured image signal indicating the captured image of the first area 400A (step S158).

[0322] Then, the first processor 90A determines whether the first light quantity P1 is equal to or greater than the second threshold value Pth2 (step S159). When the first light quantity P1 is equal to or greater than the second threshold value Pth2 (step S159: Yes), the first processor 90A transmits a first stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S160).

[0323] Then, the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S161). After transmitting the second stack start signal to the third projector 1C, the first processor 90A ends the third determination process.

[0324] When the first light quantity P1 is less than the second threshold value Pth2 (step S159: No), the first processor 90A determines whether the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S162).

[0325] When the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S162: Yes), the first processor 90A transmits a second stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S163). After transmitting the second stack start signal to the third projector 1C, the first processor 90A ends the third determination process.

[0326] When the first light quantity P1 is less than the first threshold value Pth1 (step S162: No), the first processor 90A proceeds to step S126 shown in FIG. 28. The above is the description of the third determination process executed by the first processor 90A.

[0327] In the third embodiment, after at least one of the fourth image 310B and the fifth image 310C is stacked on the first image 300A, the first processor 90A executes the same first release process as in the second embodiment. Therefore, the description of the first release process in the third embodiment is omitted.

[0328] In the third embodiment, after at least one of the sixth image 320C and the eighth image 310A is stacked on the second image 300B, the first processor 90A executes the fourth release process.

[0329] FIG. 33 is a first flowchart showing the fourth release process executed by the first processor 90A. FIG. 34 is a second flowchart showing the fourth release process. FIG. 35 is a third flowchart showing the fourth release process. The first processor 90A executes the fourth release process shown in FIGS. 33 to 35 by reading and executing a program from the first storage device 80A.

[0330] As shown in FIG. 33, when the first processor 90A starts the fourth unlocking process, first, it determines the number of images stacked in the second image 300B (step S171). When the number of images stacked in the second image 300B is two (step S171: two), the first processor 90A calculates a ninth light quantity P9 indicating the brightness of the second area 400B based on a captured image signal indicating the captured image of the second area 400B (step S172).

[0331] Subsequently, the first processor 90A determines whether the ninth light quantity P9 is equal to or greater than a second threshold value Pth2 (step S173). When the ninth light quantity P9 is equal to or greater than the second threshold value Pth2 (step S173: Yes), the first processor 90A ends the fourth unlocking process.

[0332] When the ninth light quantity P9 is less than the second threshold value Pth2 (step S173: No), the first processor 90A determines whether the ninth light quantity P9 is equal to or greater than a first threshold value Pth1 and less than the second threshold value Pth2 (step S174).

[0333] When the ninth light quantity P9 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S174: Yes), the first processor 90A ends stacking the eighth image 310A in the second image 300B by controlling the first driving device 30A and the first optical device 40A, and projects the first image 300A onto the first area 400A (step S175). After the first processor 90A projects the first image 300A onto the first area 400A, it ends the fourth unlocking process.

[0334] When the ninth light quantity P9 is less than the first threshold value Pth1 (step S174: No), the first processor 90A transmits an end-of-stack signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S176). Then, the first processor 90A terminates stacking the eighth image 310A on the second image 300B by controlling the first driving device 30A and the first optical device 40A, and projects the first image 300A onto the first area 400A (step S177). After projecting the first image 300A onto the first area 400A, the first processor 90A terminates the fourth release process.

[0335] When the number of images stacked on the second image 300B is one (step S171: one), the first processor 90A proceeds to step S178 shown in FIG. 34.

[0336] As shown in FIG. 34, when the first processor 90A proceeds to step S178, it determines which of the sixth image 320C and the eighth image 310A is stacked on the second image 300B (step S178).

[0337] When the sixth image 320C is stacked on the second image 300B (step S178: sixth image), the first processor 90A calculates a ninth light quantity P9 indicating the brightness of the second area 400B based on a captured image signal indicating the captured image of the second area 400B (step S179).

[0338] Subsequently, the first processor 90A determines whether the ninth light quantity P9 is greater than or equal to a second threshold value Pth2 (step S180). When the ninth light quantity P9 is greater than or equal to the second threshold value Pth2 (step S180: Yes), the first processor 90A stacks the eighth image 310A on the second image 300B by controlling the first driving device 30A and the first optical device 40A (step S181). After stacking the eighth image 310A on the second image 300B, the first processor 90A terminates the fourth release process.

[0339] When the ninth light quantity P9 is less than the second threshold value Pth2 (step S180: No), the first processor 90A determines whether the ninth light quantity P9 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S182).

[0340] When the ninth light quantity P9 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S182: Yes), the first processor 90A ends the fourth release process.

[0341] When the ninth light quantity P9 is less than the first threshold value Pth1 (step S182: No), the first processor 90A transmits a stack end signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S183). After transmitting the stack end signal to the third projector 1C, the first processor 90A ends the fourth release process.

[0342] When the eighth image 310A is stacked on the second image 300B (step S178: the eighth image), the first processor 90A proceeds to step S184 shown in FIG. 35.

[0343] As shown in FIG. 35, when the first processor 90A proceeds to step S184, it calculates a ninth light quantity P9 indicating the brightness of the second area 400B based on a captured image signal indicating the captured image of the second area 400B (step S184).

[0344] Subsequently, the first processor 90A determines whether the ninth light quantity P9 is equal to or greater than the second threshold value Pth2 (step S185). When the ninth light quantity P9 is equal to or greater than the second threshold value Pth2 (step S185: Yes), the first processor 90A transmits a third stack start signal to the third projector 1C as an interrupt signal via the first communication device 70A (step S186). After transmitting the third stack start signal to the third projector 1C, the first processor 90A ends the fourth release process.

[0345] When the ninth light quantity P9 is less than the second threshold value Pth2 (step S185: No), the first processor 90A determines whether the ninth light quantity P9 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S187).

[0346] When the ninth light quantity P9 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2 (step S187: Yes), the first processor 90A ends the fourth release process.

[0347] When the ninth light quantity P9 is less than the first threshold value Pth1 (step S187: No), the first processor 90A ends stacking the eighth image 310A on the second image 300B by controlling the first driving device 30A and the first optical device 40A, and projects the first image 300A onto the first area 400A (step S188). After the first processor 90A projects the first image 300A onto the first area 400A, the first processor 90A ends the fourth release process. The above is the description of the fourth release process executed by the first processor 90A.

[0348] In the third embodiment, the first processor 90A executes the fifth release process after at least one of the seventh image 320B and the ninth image 320A is stacked on the third image 300C.

[0349] FIG. 36 is a first flowchart showing the fifth release process executed by the first processor 90A. FIG. 37 is a second flowchart showing the fifth release process. FIG. 38 is a third flowchart showing the fifth release process. The first processor 90A executes the fifth release process shown in FIGS. 36 to 38 by reading and executing a program from the first storage device 80A.

[0350] As shown in FIG. 36, when the first processor 90A starts the fifth release process, first, it determines the number of images stacked in the third image 300C (step S191). When the number of images stacked in the third image 300C is two (step S181: two), the first processor 90A calculates a tenth light quantity P10 indicating the brightness of the third region 400C based on a captured image signal indicating the captured image of the third region 400C (step S192).

[0351] Subsequently, the first processor 90A determines whether the tenth light quantity P10 is greater than or equal to a second threshold value Pth2 (step S193). When the tenth light quantity P10 is greater than or equal to the second threshold value Pth2 (step S193: Yes), the first processor 90A ends the fifth release process.

[0352] When the tenth light quantity P10 is less than the second threshold value Pth2 (step S193: No), the first processor 90A determines whether the tenth light quantity P10 is greater than or equal to a first threshold value Pth1 and less than the second threshold value Pth2 (step S194).

[0353] When the tenth light quantity P10 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S194: Yes), the first processor 90A ends stacking the ninth image 320A in the third image 300C by controlling the first driving device 30A and the first optical device 40A, and projects the first image 300A onto the first region 400A (step S195). After the first processor 90A projects the first image 300A onto the first region 400A, it ends the fifth release process.

[0354] When the first light quantity P10 is less than the first threshold value Pth1 (step S194: No), the first processor 90A transmits an end-of-stack signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S196). Then, the first processor 90A terminates stacking the ninth image 320A on the third image 300C by controlling the first driving device 30A and the first optical device 40A, and projects the first image 300A onto the first area 400A (step S197). After projecting the first image 300A onto the first area 400A, the first processor 90A terminates the fifth release process.

[0355] When the number of images stacked on the third image 300C is one (step S191: one), the first processor 90A proceeds to step S198 shown in FIG. 37.

[0356] As shown in FIG. 37, when the first processor 90A proceeds to step S198, it determines which of the seventh image 320B and the ninth image 320A is stacked on the third image 300C (step S198).

[0357] When the seventh image 320B is stacked on the third image 300C (step S198: seventh image), the first processor 90A calculates a tenth light quantity P10 indicating the brightness of the third area 400C based on a captured image signal indicating the captured image of the third area 400C (step S199).

[0358] Subsequently, the first processor 90A determines whether the tenth light quantity P10 is greater than or equal to the second threshold value Pth2 (step S200). When the tenth light quantity P10 is greater than or equal to the second threshold value Pth2 (step S200: Yes), the first processor 90A stacks the ninth image 320A on the third image 300C by controlling the first driving device 30A and the first optical device 40A (step S201). After stacking the ninth image 320A on the third image 300C, the first processor 90A terminates the fifth release process.

[0359] When the first processor 90A determines that the tenth light quantity P10 is less than the second threshold value Pth2 (step S200: No), it determines whether the tenth light quantity P10 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S202).

[0360] When the tenth light quantity P10 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S202: Yes), the first processor 90A ends the fifth release process.

[0361] When the tenth light quantity P10 is less than the first threshold value Pth1 (step S202: No), the first processor 90A transmits an end-of-stack signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S203). After transmitting the end-of-stack signal to the second projector 1B, the first processor 90A ends the fifth release process.

[0362] When the ninth image 320A is stacked on the third image 300C (step S198: the ninth image), the first processor 90A proceeds to step S204 shown in FIG. 38.

[0363] As shown in FIG. 38, when the first processor 90A proceeds to step S204, it calculates a tenth light quantity P10 indicating the brightness of the third area 400C based on a captured image signal indicating the captured image of the third area 400C (step S204).

[0364] Subsequently, the first processor 90A determines whether the tenth light quantity P10 is greater than or equal to the second threshold value Pth2 (step S205). When the tenth light quantity P10 is greater than or equal to the second threshold value Pth2 (step S205: Yes), the first processor 90A transmits a fourth stack start signal to the second projector 1B as an interrupt signal via the first communication device 70A (step S206). After transmitting the fourth stack start signal to the second projector 1B, the first processor 90A ends the fifth release process.

[0365] When the first light quantity P10 is less than the second threshold value Pth2 (step S205: No), the first processor 90A determines whether the first light quantity P10 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S207).

[0366] When the first light quantity P10 is greater than or equal to the first threshold value Pth1 and less than the second threshold value Pth2 (step S207: Yes), the first processor 90A ends the fifth release process.

[0367] When the first light quantity P10 is less than the first threshold value Pth1 (step S207: No), the first processor 90A ends stacking the ninth image 320A on the third image 300C by controlling the first driving device 30A and the first optical device 40A, and projects the first image 300A onto the first area 400A (step S208). After the first processor 90A projects the first image 300A onto the first area 400A, the first processor 90A ends the fifth release process. The above is the description of the fifth release process executed by the first processor 90A.

[0368] In the third embodiment, the second processor 90B executes the same second interrupt process as in the second embodiment, and the third processor 90C executes the same third interrupt process as in the second embodiment.

[0369] As described above, the first processor 90A executes the first initial process, the third determination process, the first release process, the fourth release process, and the fifth release process. The second processor 90B executes the second initial process and the second interrupt process. The third processor 90C executes the third initial process and the third interrupt process. Thereby, the projection method of the third embodiment described below is realized.

[0370] The projection method of the third embodiment includes the following first step to sixth step. (First step) The first projector 1A projects the first image 300A onto the first area 400A. (Second step) The second projector 1B projects the second image 300B onto the second area 400B. (Step 3) The third projector 1C projects the third image 300C onto the third area 400C. (Step 4) Detect the presence or absence of a person in the first monitoring area including the first area 400A. (Step 5) When the person exists in the first monitoring area, obtain the first light quantity P1 indicating the brightness of the first area 400A. (Step 6) When the first light quantity P1 is equal to or greater than the first threshold value Pth1, in the first area 400A, the second projector 1B stacks the fourth image 310B identical to the first image 300A on the first image 300A. (Step 7) When the first light quantity P1 is equal to or greater than the second threshold value Pth2, in the first area 400A, the third projector 1C stacks the fifth image 310C identical to the first image 300A on the first image 300A.

[0371] The first step is realized by the first processor 90A executing the first initial process. The second step is realized by the second processor 90B executing the second initial process. The third step is realized by the third processor 90C executing the third initial process. The fourth step is realized by the first processor 90A executing step S111 of the third determination process shown in FIG. 26. The fifth step is realized by the first processor 90A executing steps S112 and S113 of the third determination process shown in FIG. 26. The sixth step is realized by the first processor 90A executing steps S114 and S115 of the third determination process shown in FIG. 26, and the second processor 90B executing steps S91 to S93 of the second interrupt process shown in FIG. 19. The seventh step is realized by the first processor 90A executing steps S114 and S116 of the third determination process shown in FIG. 26, and the third processor 90C executing steps S101 to S103 of the third interrupt process shown in FIG. 20.

[0372] According to the above projection method, when a person exists in the first monitoring area and the first light quantity P1 is equal to or greater than the second threshold value Pth2, the fourth image 310B and the fifth image 310C are stacked on the first image 300A in the first area 400A.

[0373] When a person exists in the first monitoring area, it is of the highest priority to project the first image 300A onto the first area 400A by the first projector 1A set to the first priority. Further, when the first light quantity P1 is equal to or greater than the second threshold value Pth2 that is greater than the first threshold value Pth1, compared with the case where the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected onto the first area 400A by the first projector 1A is recognized by the viewer as an image with extremely low brightness. In this case, by stacking the fourth image 310B and the fifth image 310C that are the same as the first image 300A on the first image 300A, the brightness of the first image 300A displayed in the first area 400A can be tripled by simple calculation. Therefore, the visibility of the first image 300A projected by the first projector 1A set to the first priority can be improved.

[0374] The projection method of the third embodiment further includes the following eighth to twelfth steps. (Eighth step) When the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, detect the presence or absence of a person in the third monitoring area including the third area 400C. (Ninth step) When no person exists in the third monitoring area, the third projector 1C stacks the fifth image 310C on the first image 300A in the first area 400A. (Tenth step) When a person exists in the third monitoring area, detect the presence or absence of a person in the second monitoring area including the second area 400B. (Eleventh step) When a person exists in the second monitoring area, the third projector 1C stacks the fifth image 310C on the first image 300A in the first area 400A. (Twelfth step) When no person exists in the second monitoring area, the second projector 1B stacks the fourth image 310B on the first image 300A in the first area 400A.

[0375] From step 8 to step 12, the first processor 90A executes steps S117 to S123 of the third determination process shown in FIG. 27, the second processor 90B executes steps S91, S92, and S93 of the second interrupt process shown in FIG. 19, and the third processor 90C executes steps S101, S102, and S103 of the third interrupt process shown in FIG. 20, thereby realizing the process.

[0376] According to the above projection method, when a person exists in the first monitoring area, the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, and no person exists in the third monitoring area, the fifth image 310C is stacked on the first image 300A in the first area 400A.

[0377] When a person exists in the first monitoring area, it is most prioritized to project the first image 300A onto the first area 400A by the first projector 1A set to the first priority. When the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, compared with the case where the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected onto the first area 400A by the first projector 1A is recognized by the viewer as an image with low brightness. On the other hand, since there is no person who may view the third image 300C, the necessity of projecting the third image 300C onto the third area 400C is low. Therefore, in this case, by stacking the fifth image 310C on the first image 300A by the third projector 1C set to the third priority with the lowest priority, the visibility of the first image 300A projected by the first projector 1A set to the first priority with the highest priority can be improved. Also, in this case, the second projector 1B set to the second priority with a higher priority than the third projector 1C can continue to project the second image 300B onto the second area 400B.

[0378] Also, according to the above projection method, when a person exists in the first monitoring area, the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, and a person exists in both the second monitoring area and the third monitoring area, the fifth image 310C is stacked on the first image 300A in the first area 400A.

[0379] In this case, since projecting the second image 300B by the second projector 1B set to the second priority is prioritized over projecting the third image 300C by the third projector 1C set to the third priority, the fifth image 310C is stacked on the first image 300A by the third projector 1C. Thereby, while continuously projecting the second image 300B in the second area 400B by the second projector 1B set to the second priority which has a higher priority than the third projector 1C, the visibility of the first image 300A projected by the first projector 1A set to the first priority can be improved.

[0380] Furthermore, according to the above projection method, when a person exists in the first monitoring area, the first light quantity P1 is equal to or greater than the first threshold value Pth1 and less than the second threshold value Pth2, a person exists in the third monitoring area, and a person does not exist in the second monitoring area, the fourth image 310B is stacked on the first image 300A in the first area 400A.

[0381] In this case, since there is no person who may view the second image 300B, the necessity of projecting the second image 300B onto the second area 400B is low. On the other hand, since there is a person who may view the third image 300C, the necessity of projecting the third image 300C onto the third area 400C is high. Therefore, in this case, projecting the third image 300C by the third projector 1C is prioritized over projecting the second image 300B by the second projector 1B. Thus, the second projector 1B stacks the fourth image 310B on the first image 300A. Thereby, the third projector 1C can continue to project the third image 300C onto the third area 400C while improving the visibility of the first image 300A projected by the first projector 1A set to the first priority.

[0382] The projection method of the third embodiment further includes the following 13th to 18th steps. (13th step) When the first light quantity P1 is less than the first threshold value Pth1, detect the presence or absence of a person in the second monitoring area. (14th step) When a person is present in the second monitoring area, obtain a second light quantity P2 indicating the brightness of the second area 400B. (15th step) When the second light quantity P2 is greater than or equal to the first threshold value Pth1, in the second area 400B, the third projector 1C stacks the sixth image 320C identical to the second image 300B on the second image 300B. (16th step) When no person is present in the second monitoring area, detect the presence or absence of a person in the third monitoring area. (17th step) When a person is present in the third monitoring area, obtain a third light quantity P3 indicating the brightness of the third area 400C. (18th step) When the third light quantity P3 is greater than or equal to the first threshold value Pth1, in the third area 400C, the second projector 1B stacks the seventh image 320B identical to the third image 300C on the third image 300C.

[0383] From the 13th process to the 18th process, the first processor 90A executes steps S124 to S133 of the third determination process shown in FIG. 28, the second processor 90B executes steps S91, S94, and S95 of the second interrupt process shown in FIG. 19, and the third processor 90C executes steps S101, S104, and S105 of the third interrupt process shown in FIG. 20.

[0384] According to the above projection method, when a person exists in the first monitoring area, the first light quantity P1 is less than the first threshold value Pth1, a person exists in the second monitoring area, and the second light quantity P2 is greater than or equal to the first threshold value Pth1, the sixth image 320C is stacked on the second image 300B in the second area 400B.

[0385] When a person exists in the first monitoring area, it is most prioritized to project the first image 300A onto the first area 400A by the first projector 1A set to the first priority. When the first light quantity P1 is less than the first threshold value Pth1, the first image 300A projected onto the first area 400A by the first projector 1A is not recognized by the viewer as an image with low brightness. On the other hand, since there is a person who may view the second image 300B, the necessity of projecting the second image 300B onto the second area 400B is high. Also, since the second light quantity P2 is greater than or equal to the first threshold value Pth1, the second image 300B projected onto the second area 400B is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the sixth image 320C on the second image 300B by the third projector 1C set to the third priority with the lowest priority, while continuously projecting the first image 300A onto the first area 400A by the first projector 1A set to the first priority, the visibility of the second image 300B projected by the second projector 1B set to the second priority can be improved.

[0386] Further, according to the above projection method, when a person exists in the first monitoring area, the first light quantity P1 is less than the first threshold value Pth1, no person exists in the second monitoring area, a person exists in the third monitoring area, and the third light quantity P3 is equal to or greater than the first threshold value Pth1, the seventh image 320B is stacked on the third image 300C in the third area 400C.

[0387] In this case, since there is no person who may view the second image 300B, the necessity of projecting the second image 300B onto the second area 400B is low. On the other hand, since there is a person who may view the third image 300C, the necessity of projecting the third image 300C onto the third area 400C is high. Therefore, in this case, projecting the third image 300C by the third projector 1C is prioritized over projecting the second image 300B by the second projector 1B. Further, since the third light quantity P3 is equal to or greater than the first threshold value Pth1, the third image 300C projected onto the third area 400C is recognized by the viewer as an image with low luminance. Therefore, in this case, by stacking the seventh image 320B on the third image 300C by the second projector 1B, while the first projector 1A set to the first priority continues to project the first image 300A onto the first area 400A, the visibility of the third image 300C projected by the third projector 1C can be improved.

[0388] The projection method of the third embodiment further includes the following nineteenth to twenty-second steps. (Nineteenth step) When no person exists in the first monitoring area, detect the presence or absence of a person existing in the second monitoring area. (Twentieth step) When a person exists in the second monitoring area, obtain a second light quantity P2 indicating the brightness of the second area 400B. (Twenty-first step) When the second light quantity P2 is equal to or greater than a second threshold value Pth2, in the second area 400B, the first projector 1A stacks the eighth image 310A identical to the second image 300B on the second image 300B. (Step 22) When the second light quantity P2 is equal to or greater than the second threshold value Pth2, in the second region 400B, the third projector 1C stacks the same sixth image 320C as the second image 300B on the second image 300B.

[0389] Steps 19 to 22 are realized by the first processor 90A executing steps S134 to S139 of the third determination process shown in FIG. 29, and the third processor 90C executing steps S101, S104, and S105 of the third interrupt process shown in FIG. 20.

[0390] According to the above projection method, when there is no person in the first monitoring area, there is a person in the second monitoring area, and the second light quantity P2 is equal to or greater than the second threshold value Pth2, the sixth image 320C and the eighth image 310A are stacked on the second image 300B in the second region 400B. FIG. 39 is a diagram showing a state where the sixth image 320C and the eighth image 310A are stacked on the second image 300B in the second region 400B.

[0391] When there is no person in the first monitoring area and there is a person in the second monitoring area, it is of the highest priority to project the second image 300B onto the second region 400B by the second projector 1B set to the second priority. Also, when the second light quantity P2 is equal to or greater than the second threshold value Pth2, compared with the case where the second light quantity P2 is less than the first threshold value Pth1, the second image 300B projected onto the second region 400B by the second projector 1B is recognized by the viewer as an image with extremely low brightness. In this case, by stacking the same sixth image 320C and eighth image 310A as the second image 300B on the second image 300B, the visibility of the second image 300B projected by the second projector 1B set to the second priority can be improved.

[0392] The projection method of the third embodiment further includes the following steps 19 to 22. (Step 23) When there is no person in the second monitoring area, detect the presence or absence of a person in the third monitoring area. (Step 24) When a person exists in the third monitoring area, obtain a third light quantity P3 indicating the brightness of the third area 400C. (Step 25) When the third light quantity P3 is greater than or equal to the second threshold value Pth2, in the third area 400C, the first projector 1A stacks the same ninth image 320A as the third image 300C on the third image 300C. (Step 26) When the third light quantity P3 is greater than or equal to the second threshold value Pth2, in the third area 400C, the second projector 1B stacks the same seventh image 320B as the third image 300C on the third image 300C.

[0393] Steps 23 to 26 are realized by the first processor 90A executing steps S150 to S155 of the third determination process shown in FIG. 31 and the second processor 90B executing steps S91, S94, and S95 of the second interrupt process shown in FIG. 19.

[0394] According to the above projection method, when there is no person in the first monitoring area and the second monitoring area, there is a person in the third monitoring area, and the third light quantity P3 is greater than or equal to the second threshold value Pth2, the seventh image 320B and the ninth image 320A are stacked on the third image 300C in the third area 400C. FIG. 40 is a diagram showing a state where the seventh image 320B and the ninth image 320A are stacked on the third image 300C in the third area 400C.

[0395] When there is no person in the first monitoring area and the second monitoring area, and there is a person in the third monitoring area, it is of top priority to project the third image 300C onto the third area 400C by the third projector 1C set to the third priority. Also, when the third light quantity P3 is equal to or greater than the second threshold value Pth2, compared with the case where the third light quantity P3 is less than the first threshold value Pth1, the third image 300C projected onto the third area 400C by the third projector 1C is recognized by the viewer as an image with extremely low brightness. In this case, by stacking the same seventh image 320B and ninth image 320A as the third image 300C on the third image 300C, the visibility of the third image 300C projected by the third projector 1C set to the third priority can be improved.

[0396] As described above, the first embodiment, the second embodiment, and the third embodiment of the present disclosure have been described. However, the technical scope of the present disclosure is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

[0397] In each embodiment, as an example of the first brightness information indicating the brightness of the first area 400A, the form of acquiring the first light quantity P1, which is the illuminance, has been exemplified. The present disclosure is not limited to this. For example, based on the captured image of the first area 400A obtained by photographing the first area 400A while projecting a test pattern onto the first area 400A, the contrast of the test pattern may be calculated as the first brightness information. When acquiring the contrast as the first brightness information, for example, the first threshold value Pth1 may be set to 50% of the normal value, and the second threshold value Pth2 may be set to 25% of the normal value. The same applies to other brightness information. In this case, whether the first brightness information is equal to or greater than the first threshold value Pth1 is an example of the first condition, and the fact that the first brightness information is equal to or greater than the first threshold value Pth1 is an example of satisfying the first condition.

[0398] In each embodiment, an example is given in which the first light quantity P1 is acquired at a predetermined time interval. The present disclosure is not limited to this. For example, when a captured image of the first region 400A is acquired at an interval shorter than the time interval at which the first light quantity P1 is acquired, and it is detected that the first image 300A projected onto the first region 400A has become thinner, the first light quantity P1 may be acquired. In this case, the contrast of the test pattern may be calculated based on the captured image of the first region 400A obtained while projecting the test pattern onto the first region 400A, and it may be determined whether the first image 300A has become thinner based on the calculated value of the contrast.

[0399] In each embodiment, an example is given in which the first projector 1A operates as a primary device and the second projector 1B and the third projector 1C operate as secondary devices. The present disclosure is not limited to this. For example, a personal computer may be provided as a primary device, and the personal computer may adopt a configuration in which the first projector 1A, the second projector 1B, and the third projector 1C are controlled. Further, in this aspect, a video signal may be transmitted from the personal computer to the first projector 1A, the second projector 1B, and the third projector 1C via a distributor.

[0400] 〔Summary of the present disclosure〕 Hereinafter, a summary of the present disclosure is appended.

[0401] (Appended Note 1) A projection method including: the first projector projecting a first image onto a first region; the second projector projecting a second image onto a second region different from the first region; acquiring first brightness information indicating the brightness of the first region; and when the first brightness information satisfies a first condition, the second projector stacking, in the first region, a fourth image identical to the first image on the first image.

[0402] According to the above projection method, when the first brightness information satisfies the first condition, in the first area, the second projector stacks the fourth image, which is the same as the first image, on the first image. Therefore, according to the above projection method, even when the first brightness information satisfies the first condition, an image can be projected onto the first area. Also, when the first brightness information does not satisfy the first condition, the second projector continues to project the second image onto the second area. The first projector projects the first image onto the first area regardless of whether the first brightness information satisfies the first condition. Therefore, according to the projection method of Appendix 1, when the first brightness information does not satisfy the first condition, the first image and the second image can be projected respectively.

[0403] (Appendix 2) Stacking the fourth image on the first image includes, when the first brightness information is equal to or greater than the first threshold value, the second projector stacking the fourth image on the first image in the first area, and is the projection method described in Appendix 1.

[0404] According to the above projection method, when the first brightness information is equal to or greater than the first threshold value, the second projector stacks the fourth image on the first image in the first area. When the first brightness information is equal to or greater than the first threshold value, compared with the case where the first brightness information is less than the first threshold value, the first image projected onto the first area by the first projector is recognized by the viewer as an image with low brightness. In this case, by stacking the fourth image, which is the same as the first image, on the first image, the brightness of the first image displayed in the first area can be doubled by simple calculation, so the visibility of the first image can be improved.

[0405] (Appendix 3) Stacking the fourth image on the first image includes, when the first brightness information is equal to or greater than the first threshold value, the first projector sending a first signal to the second projector, and when the second projector receives the first signal, the second projector stacking the fourth image on the first image in the first area, and is the projection method described in Appendix 2.

[0406] According to the above projection method, when the first brightness information is equal to or greater than the first threshold, the first projector can request the second projector to stack the fourth image on the first image at an appropriate timing by transmitting a first signal to the second projector. In addition, since the second projector only needs to perform a stacking operation when it receives the first signal, the processing load on the second projector can be reduced.

[0407] (Appendix 4) The projection method according to Appendix 2 or 3, further comprising: a third projector projecting a third image onto a third region different from the first region and the second region; and when the first brightness information is equal to or greater than a second threshold greater than the first threshold, in the first region, the third projector stacking the fifth image identical to the first image on the first image and the fourth image.

[0408] According to the above projection method, when the first brightness information is equal to or greater than the second threshold, the fourth image and the fifth image are stacked on the first image in the first region. When the first brightness information is equal to or greater than a second threshold greater than the first threshold, compared with the case where the first brightness information is less than the first threshold, the first image projected onto the first region by the first projector is recognized by the viewer as an image with extremely low brightness. In this case, by stacking the fourth image and the fifth image identical to the first image on the first image, the brightness of the first image displayed in the first region can be tripled by simple calculation, so the visibility of the first image projected by the first projector can be improved.

[0409] (Appendix 5) The projection method according to Appendix 4, wherein stacking the fifth image on the first image includes: when the first brightness information is equal to or greater than the second threshold, the first projector transmitting a second signal to the third projector; and when the third projector receives the second signal, stacking the fifth image on the first image in the first region.

[0410] According to the above projection method, when the first brightness information is equal to or greater than the second threshold value, the first projector can request the third projector to stack the fifth image on the first image at an appropriate timing by transmitting the second signal to the third projector. Further, since the third projector only needs to perform a stacking operation when it receives the second signal, the processing load on the third projector can be reduced.

[0411] (Appendix 6) When the first brightness information is equal to or greater than the first threshold value and less than the second threshold value, detecting the presence or absence of a person in the third monitoring area including the third area; when no person is present in the third monitoring area, the third projector stacking the fifth image on the first image in the first area; when a person is present in the third monitoring area, detecting the presence or absence of a person in the second monitoring area including the second area; when a person is present in the second monitoring area, the third projector stacking the fifth image on the first image in the first area; when no person is present in the second monitoring area, the second projector stacking the fourth image on the first image in the first area. The projection method according to Appendix 4 further includes the above steps.

[0412] According to the above projection method, when the first brightness information is equal to or greater than the first threshold value and less than the second threshold value, and no person is present in the third monitoring area, the fifth image is stacked on the first image in the first area.

[0413] When the first brightness information is equal to or greater than the first threshold and less than the second threshold, compared with the case where the first brightness information is less than the first threshold, the first image projected onto the first area by the first projector is recognized by the viewer as an image with low brightness. On the other hand, since there is no person who may view the third image, the necessity of projecting the third image onto the third area is low. Therefore, in this case, by stacking the fifth image on the first image by the third projector, the visibility of the first image projected by the first projector can be improved. Also, in this case, the second projector can continue to project the second image onto the second area.

[0414] Also, according to the above projection method, when the first brightness information is equal to or greater than the first threshold and less than the second threshold, and there are people in both the second monitoring area and the third monitoring area, the fifth image is stacked on the first image in the first area.

[0415] In this case, by stacking the fifth image on the first image by the third projector, while the second projector continues to project the second image onto the second area, the visibility of the first image projected by the first projector can be improved.

[0416] Furthermore, according to the above projection method, when the first brightness information is equal to or greater than the first threshold and less than the second threshold, there is a person in the third monitoring area, and there is no person in the second monitoring area, the fourth image is stacked on the first image in the first area.

[0417] In this case, since there is no person who may view the second image, the necessity of projecting the second image onto the second area is low. On the other hand, since there is a person who may view the third image, the necessity of projecting the third image onto the third area is high. Therefore, in this case, projecting the third image by the third projector is prioritized over projecting the second image by the second projector, so the fourth image is stacked on the first image by the second projector. Thereby, while the third projector continues to project the third image onto the third area, the visibility of the first image projected by the first projector can be improved.

[0418] (Appendix 7) When the first brightness information is less than the first threshold value, detecting the presence or absence of a person in a second monitoring area including the second area, and when the person is present in the second monitoring area, obtaining second brightness information indicating the brightness of the second area, and when the second brightness information is greater than or equal to the first threshold value, in the second area, the third projector stacking a sixth image identical to the second image on the second image, and when the person is not present in the second monitoring area, detecting the presence or absence of a person in a third monitoring area including the third area, and when the person is not present in the third monitoring area, obtaining the second brightness information, and when the second brightness information is greater than or equal to the first threshold value, the third projector stacking the sixth image in the second area on the second image, and when the person is present in the third monitoring area, obtaining third brightness information indicating the brightness of the third area, and when the third brightness information is greater than or equal to the first threshold value, in the third area, the second projector stacking a seventh image identical to the third image on the third image, further comprising the projection method according to Appendix 4.

[0419] According to the above projection method, when the first brightness information is less than the first threshold value, a person is present in the second monitoring area, and the second brightness information is greater than or equal to the first threshold value, the sixth image is stacked on the second image in the second area.

[0420] When the first brightness information is less than the first threshold value, the first image projected onto the first area by the first projector is not recognized by the viewer as an image with low brightness. On the other hand, since there may be a person who may view the second image, it is highly necessary to project the second image onto the second area. Also, since the second brightness information is equal to or greater than the first threshold value, the second image projected onto the second area is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the sixth image on the second image by the third projector, the visibility of the second image projected by the second projector can be improved.

[0421] Also, according to the above projection method, when the first brightness information is less than the first threshold value, there are no persons in both the second monitoring area and the third monitoring area, and the second brightness information is equal to or greater than the first threshold value, the sixth image is stacked on the second image in the second area.

[0422] When there are no persons in both the second monitoring area and the third monitoring area, the necessity of projecting the second image and the third image is low. However, since the second brightness information is equal to or greater than the first threshold value, when a viewer of the second image appears, the second image projected onto the second area may be recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the sixth image on the second image by the third projector, when a viewer of the second image appears, a highly visible second image can be provided to the viewer.

[0423] Furthermore, according to the above projection method, when the first brightness information is less than the first threshold value, there is no person in the second monitoring area, there is a person in the third monitoring area, and the third brightness information is equal to or greater than the first threshold value, the seventh image is stacked on the third image in the third area.

[0424] In this case, since there is no person who may view the second image, the necessity of projecting the second image onto the second area is low. On the other hand, since there is a person who may view the third image, the necessity of projecting the third image onto the third area is high. Therefore, in this case, projecting the third image by the third projector is prioritized over projecting the second image by the second projector. Also, since the third brightness information is equal to or greater than the first threshold value, the third image projected onto the third area is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking the seventh image on the third image by the second projector, the visibility of the third image projected by the third projector can be improved.

[0425] (Appendix 8) After both the fourth image and the fifth image are stacked on the first image, acquiring fourth brightness information indicating the brightness of the first area, and when the fourth brightness information is less than the first threshold value, the second projector projecting the second image onto the second area, and when the fourth brightness information is less than the first threshold value, the third projector projecting the third image onto the third area, and when the fourth brightness information is equal to or greater than the first threshold value and less than the second threshold value, the second projector projecting the second image onto the second area, further including the projection method according to Appendix 4.

[0426] When the fourth brightness information acquired after both the fourth image and the fifth image are stacked on the first image is less than the first threshold value, there is no longer a need to stack both the fourth image and the fifth image on the first image. Therefore, in this case, the second projector projects the second image onto the second area again, and the third projector projects the third image onto the third area again. Thereby, the display state of the images can be returned to a state where all of the first image, the second image, and the third image are displayed at an appropriate timing.

[0427] Also, when the fourth brightness information is equal to or greater than the first threshold value and less than the second threshold value, it is not necessary to stack either the fourth image or the fifth image on the first image. In this case, the second projector can resume providing the second image by projecting the second image onto the second area again.

[0428] (Appendix 9) After the fifth image among the fourth image and the fifth image is stacked on the first image, obtaining fifth brightness information indicating the brightness of the first area, and when the fifth brightness information is less than the first threshold value, the third projector projects the third image onto the third area, and when the fifth brightness information is equal to or greater than the second threshold value, the second projector stacks the fourth image on the first image in the first area. The projection method according to Appendix 6, further comprising:

[0429] If the fifth brightness information obtained after the fifth image among the fourth image and the fifth image is stacked on the first image is less than the first threshold value, it is no longer necessary to stack the fifth image on the first image. Therefore, in this case, the third projector projects the third image onto the third area again, so that the display state of the images can be returned to the state of displaying all of the first image, the second image, and the third image at an appropriate timing.

[0430] Also, when the fifth brightness information obtained after the fifth image among the fourth image and the fifth image is stacked on the first image is equal to or greater than the second threshold value, stacking only the fifth image on the first image cannot sufficiently improve the brightness of the first image. Therefore, in this case, by stacking the fourth image on the first image by the second projector, the visibility of the first image projected by the first projector can be improved.

[0431] (Appendix 10) After the fourth image among the fourth image and the fifth image is stacked on the first image, obtaining sixth brightness information indicating the brightness of the first area; when the sixth brightness information is less than the first threshold value, the second projector projects the second image onto the second area; when the sixth brightness information is greater than or equal to the second threshold value, the third projector stacks the fifth image on the first image in the first area. The projection method according to Appendix 6 further includes the above steps.

[0432] When the sixth brightness information obtained after the fourth image among the fourth image and the fifth image is stacked on the first image is less than the first threshold value, it is no longer necessary to stack the fourth image on the first image. Therefore, in this case, by the second projector projecting the second image onto the second area again, the display state of the image can be restored to the state where all of the first image, the second image, and the third image are displayed at an appropriate timing.

[0433] Also, when the sixth brightness information obtained after the fourth image among the fourth image and the fifth image is stacked on the first image is greater than or equal to the second threshold value, simply stacking the fourth image on the first image cannot sufficiently improve the brightness of the first image. Therefore, in this case, by stacking the fifth image on the first image by the third projector, the visibility of the first image projected by the first projector can be improved.

[0434] (Appendix 11) After the sixth image is stacked on the second image, obtaining seventh brightness information indicating the brightness of the second area; when the seventh brightness information is less than the first threshold value, the third projector projects the third image onto the third area. The projection method according to Appendix 7 further includes the above steps.

[0435] When the seventh brightness information obtained after the sixth image is stacked on the second image is less than the first threshold value, there is no longer a need to stack the sixth image on the second image. Therefore, in this case, the third projector can project the third image again onto the third area, and return the image display state to a state where all of the first image, the second image, and the third image are displayed at an appropriate timing.

[0436] (Appendix 12) After the seventh image is stacked on the third image, obtaining eighth brightness information indicating the brightness of the third area, and when the eighth brightness information is less than the first threshold value, the second projector projects the second image onto the second area. The projection method according to Appendix 7, further comprising:

[0437] When the eighth brightness information obtained after the seventh image is stacked on the third image is less than the first threshold value, there is no longer a need to stack the seventh image on the third image. Therefore, in this case, the second projector can project the second image again onto the second area, and return the image display state to a state where all of the first image, the second image, and the third image are displayed at an appropriate timing.

[0438] (Appendix 13) The third projector projects a third image onto a third area different from the first area and the second area, detects the presence or absence of a person in a first monitoring area including the first area, and when the person is present in the first monitoring area, obtaining the first brightness information, and when the first brightness information is greater than or equal to a second threshold value greater than the first threshold value, in the first area, the third projector stacks a fifth image identical to the first image on the first image. The projection method according to Appendix 2, comprising:

[0439] According to the above projection method, when a person is present in the first monitoring area and the first brightness information is greater than or equal to the second threshold value, the fourth image and the fifth image are stacked on the first image in the first area.

[0440] When a person exists in the first monitoring area, it is highly necessary to project a first image onto the first area by the first projector. Also, when the first brightness information is equal to or greater than a second threshold that is greater than the first threshold, compared with the case where the first brightness information is less than the first threshold, the first image projected onto the first area by the first projector is recognized by the viewer as an image with extremely low brightness. In this case, by stacking the same fourth and fifth images as the first image on the first image, the brightness of the first image displayed in the first area can be tripled by simple calculation, so the visibility of the first image projected by the first projector can be improved.

[0441] (Appendix 14) When the first brightness information is equal to or greater than the first threshold and less than the second threshold, detecting the presence or absence of a person in the third monitoring area including the third area, and when no person exists in the third monitoring area, the third projector stacking the fifth image on the first image in the first area, and when a person exists in the third monitoring area, detecting the presence or absence of a person in the second monitoring area including the second area, and when a person exists in the second monitoring area, the third projector stacking the fifth image on the first image in the first area, and when no person exists in the second monitoring area, the second projector stacking the fourth image on the first image in the first area, the projection method according to Appendix 13 further including the above.

[0442] According to the above projection method, when a person exists in the first monitoring area, the first brightness information is equal to or greater than the first threshold and less than the second threshold, and no person exists in the third monitoring area, the fifth image is stacked on the first image in the first area.

[0443] When there is a person in the first monitoring area, it is highly necessary to project a first image onto a first area by a first projector. When the first brightness information is equal to or greater than a first threshold value and less than a second threshold value, compared with the case where the first brightness information is less than the first threshold value, the first image projected onto the first area by the first projector is recognized by viewers as an image with low brightness. On the other hand, since there is no person who may view the third image, the necessity of projecting the third image onto the third area is low. Therefore, in this case, by stacking a fifth image on the first image by a third projector, the visibility of the first image projected by the first projector can be improved. Also, in this case, the second projector can continue to project a second image onto the second area.

[0444] Also, according to the above projection method, when there is a person in the first monitoring area, the first brightness information is equal to or greater than the first threshold value and less than the second threshold value, and there are persons in both the second monitoring area and the third monitoring area, a fifth image is stacked on the first image in the first area.

[0445] In this case, by stacking the fifth image on the first image by the third projector 1C, the visibility of the first image projected by the first projector can be improved while the second projector continues to project a second image onto the second area.

[0446] Furthermore, according to the above projection method, when there is a person in the first monitoring area, the first brightness information is equal to or greater than the first threshold value and less than the second threshold value, there is a person in the third monitoring area, and there is no person in the second monitoring area, a fourth image is stacked on the first image in the first area.

[0447] In this case, since there is no person who may view the second image, the necessity of projecting the second image onto the second area is low. On the other hand, since there is a person who may view the third image, the necessity of projecting the third image onto the third area is high. Therefore, in this case, projecting the third image by the third projector is prioritized over projecting the second image by the second projector, so the second projector stacks the fourth image on the first image. Thereby, while the third projector continues to project the third image onto the third area, the visibility of the first image projected by the first projector can be improved.

[0448] (Appendix 15) When the first brightness information is less than the first threshold value, detecting the presence or absence of a person in the second monitoring area; when the person is present in the second monitoring area, obtaining second brightness information indicating the brightness of the second area; when the second brightness information is greater than or equal to the first threshold value, in the second area, the third projector stacking the sixth image identical to the second image on the second image; when the person is not present in the second monitoring area, detecting the presence or absence of a person in the third monitoring area; when the person is present in the third monitoring area, obtaining third brightness information indicating the brightness of the third area; when the third brightness information is greater than or equal to the first threshold value, in the third area, the second projector stacking the seventh image identical to the third image on the third image. The projection method according to Appendix 14 further includes the above steps.

[0449] According to the above projection method, when a person is present in the first monitoring area, the first brightness information is less than the first threshold value, a person is present in the second monitoring area, and the second brightness information is greater than or equal to the first threshold value, the sixth image is stacked on the second image in the second area.

[0450] When there is a person in the first monitoring area, it is highly necessary to project a first image onto a first area by a first projector. When the first brightness information is less than a first threshold value, the first image projected onto the first area by the first projector is not recognized by the viewer as an image with low brightness. On the other hand, since there is a person who may view the second image, it is highly necessary to project the second image onto a second area. Also, since the second brightness information is equal to or greater than the first threshold value, the second image projected onto the second area is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking a sixth image on the second image by a third projector, while continuously projecting the first image onto the first area by the first projector, the visibility of the second image projected by the second projector can be improved.

[0451] Also, according to the above projection method, when there is a person in the first monitoring area, the first brightness information is less than the first threshold value, there is no person in the second monitoring area, there is a person in the third monitoring area, and the third brightness information is equal to or greater than the first threshold value, a seventh image is stacked on a third image in the third area.

[0452] In this case, since there is no person who may view the second image, the necessity of projecting the second image onto the second area is low. On the other hand, since there is a person who may view the third image, the necessity of projecting the third image onto the third area is high. Therefore, in this case, projecting the third image by the third projector is prioritized over projecting the second image by the second projector. Also, since the third brightness information is equal to or greater than the first threshold value, the third image projected onto the third area is recognized by the viewer as an image with low brightness. Therefore, in this case, by stacking a seventh image on the third image by the second projector, while continuously projecting the first image onto the first area by the first projector, the visibility of the third image projected by the third projector can be improved.

[0453] (Supplementary Note 16) When the person does not exist in the first monitoring area, detecting the presence or absence of a person in the second monitoring area including the second area; when the person exists in the second monitoring area, obtaining second brightness information indicating the brightness of the second area; when the second brightness information is equal to or greater than the second threshold value, in the second area, the first projector stacking the same eighth image as the second image on the second image; when the second brightness information is equal to or greater than the second threshold value, in the second area, the third projector stacking the same sixth image as the second image on the second image. The projection method according to Supplementary Note 13 further includes the above steps.

[0454] According to the above projection method, when there is no person in the first monitoring area, there is a person in the second monitoring area, and the second brightness information is equal to or greater than the second threshold value, the sixth image and the eighth image are stacked on the second image in the second area.

[0455] When there is no person in the first monitoring area and there is a person in the second monitoring area, it is highly necessary to project the second image onto the second area by the second projector. Also, when the second brightness information is equal to or greater than the second threshold value, compared with the case where the second brightness information is less than the first threshold value, the second image projected onto the second area by the second projector is recognized by the viewer as an image with very low brightness. In this case, by stacking the same sixth image and eighth image as the second image on the second image, the visibility of the second image projected by the second projector can be improved.

[0456] (Supplementary Note 17) When the person does not exist in the second monitoring area, detecting the presence or absence of a person in the third monitoring area including the third area; when the person exists in the third monitoring area, obtaining third brightness information indicating the brightness of the third area; when the third brightness information is equal to or greater than the second threshold, in the third area, the first projector stacks the same ninth image as the third image on the third image; when the third brightness information is equal to or greater than the second threshold, in the third area, the second projector stacks the same seventh image as the third image on the third image. The projection method according to Supplementary Note 16 further includes the above.

[0457] According to the above projection method, when there is no person in the first monitoring area and the second monitoring area, there is a person in the third monitoring area, and the third brightness information is equal to or greater than the second threshold, the seventh image and the ninth image are stacked on the third image in the third area.

[0458] When there is no person in the first monitoring area and the second monitoring area, and there is a person in the third monitoring area, it is highly necessary to project the third image onto the third area by the third projector. Also, when the third brightness information is equal to or greater than the second threshold, compared with the case where the third brightness information is less than the first threshold, the third image projected onto the third area by the third projector is recognized by the viewer as an image with very low brightness. In this case, by stacking the same seventh image and ninth image as the third image on the third image, the visibility of the third image projected by the third projector can be improved.

[0459] (Supplementary Note 18) A sensor that outputs a signal indicating the brightness of the first area; a first projector that projects a first image onto the first area and obtains first brightness information indicating the brightness of the first area based on the signal output from the sensor; a second projector that stacks the same fourth image as the first image on the first image in the first area when the first brightness information satisfies the first condition. A projection system comprising the above.

[0460] According to the above projection system, when the first brightness information satisfies the first condition, the second projector stacks the fourth image on the first image in the first area brightness information. Therefore, even when the first brightness information satisfies the first condition, an image can be projected onto the first area. Also, when the first brightness information does not satisfy the first condition, the second projector continues to project the second image onto the second area. The first projector projects the first image onto the first area regardless of whether the first brightness information satisfies the first condition. Therefore, according to the above projection system, when the first brightness information does not satisfy the first condition, the first image and the second image can be projected respectively.

[0461] (Appendix 19) A program for causing a computer to cause a first projector to project a first image onto a first area, a second projector to project a second image onto a second area different from the first area, to obtain first brightness information indicating the brightness of the first area, and when the first brightness information satisfies a first condition, to cause the second projector to stack, in the first area brightness information, a fourth image identical to the first image on the first image.

[0462] According to the above program, when the first brightness information satisfies the first condition, the second projector stacks the fourth image on the first image in the first area brightness information. Therefore, even when the first brightness information satisfies the first condition, an image can be projected onto the first area. Also, when the first brightness information does not satisfy the first condition, the second projector continues to project the second image onto the second area. The first projector projects the first image onto the first area regardless of whether the first brightness information satisfies the first condition. Therefore, according to the above program, when the first brightness information does not satisfy the first condition, the first image and the second image can be projected respectively.

Explanation of Signs

[0463] 1... Projector, 1A... First projector, 1B... Second projector, 1C... Third projector, 2... Video supply device, 300A... First image, 300B... Second image, 300C... Third image, 310B... Fourth image, 310C... Fifth image, 320C... Sixth image, 320B... Seventh image, 310A... Eighth image, 320A... Ninth image, 400A... First area, 400B... Second area, 400C... Third area, 100, 200... Projection system

Claims

1. The first projector projects a first image onto a first area; The second projector projects a second image onto a second area different from the first area; Obtaining first brightness information indicating the brightness of the first area; When the first brightness information satisfies a first condition, in the first area, the second projector stacks a fourth image identical to the first image on the first image; A projection method comprising the above.

2. Stacking the fourth image on the first image means that When the first brightness information is equal to or greater than a first threshold, the second projector stacks the fourth image on the first image in the first area; The projection method according to claim 1, comprising the above.

3. Stacking the fourth image on the first image means that When the first brightness information is equal to or greater than the first threshold, the first projector transmits a first signal to the second projector; When the second projector receives the first signal, the second projector stacks the fourth image on the first image in the first area; The projection method according to claim 2, comprising the above.

4. A third projector projects a third image onto a third area different from the first area and the second area; When the first brightness information is equal to or greater than a second threshold greater than the first threshold, in the first area, the third projector stacks a fifth image identical to the first image on the first image and the fourth image; The projection method according to claim 2 or claim 3, further comprising the above.

5. Stacking the fifth image on the first image means that When the first brightness information is equal to or greater than the second threshold, the first projector transmits a second signal to the third projector, When the third projector receives the second signal, the third projector stacks the fifth image on the first image in the first region, The projection method according to claim 4, comprising:

6. When the first brightness information is equal to or greater than the first threshold and less than the second threshold, detecting the presence or absence of a person in a third monitoring region including the third region, When no person exists in the third monitoring region, the third projector stacks the fifth image on the first image in the first region, When a person exists in the third monitoring region, detecting the presence or absence of a person in a second monitoring region including the second region, When a person exists in the second monitoring region, the third projector stacks the fifth image on the first image in the first region, When no person exists in the second monitoring region, the second projector stacks the fourth image on the first image in the first region, The projection method according to claim 4, further comprising:

7. When the first brightness information is less than the first threshold, detecting the presence or absence of a person in a second monitoring region including the second region, When a person exists in the second monitoring region, obtaining second brightness information indicating the brightness of the second region, When the second brightness information is equal to or greater than the first threshold, in the second region, the third projector stacks the sixth image identical to the second image on the second image, When no person exists in the second monitoring region, detecting the presence or absence of a person in a third monitoring region including the third region, When the person does not exist in the third monitoring area, obtaining the second brightness information; When the second brightness information is equal to or greater than the first threshold, the third projector stacks the sixth image on the second image in the second area; When the person exists in the third monitoring area, obtaining third brightness information indicating the brightness of the third area; When the third brightness information is equal to or greater than the first threshold, in the third area, the second projector stacks the same seventh image as the third image on the third image; The projection method according to claim 4, further comprising:

8. After both the fourth image and the fifth image are stacked on the first image, obtaining fourth brightness information indicating the brightness of the first area; When the fourth brightness information is less than the first threshold, the second projector projects the second image in the second area; When the fourth brightness information is less than the first threshold, the third projector projects the third image in the third area; When the fourth brightness information is equal to or greater than the first threshold and less than the second threshold, the second projector projects the second image in the second area; The projection method according to claim 4, further comprising:

9. After the fifth image among the fourth image and the fifth image is stacked on the first image, obtaining fifth brightness information indicating the brightness of the first area; When the fifth brightness information is less than the first threshold, the third projector projects the third image in the third area; When the fifth brightness information is equal to or greater than the second threshold, the second projector stacks the fourth image on the first image in the first area; The projection method according to claim 6, further comprising:

10. After the fourth image among the fourth image and the fifth image is stacked on the first image, obtaining sixth brightness information indicating the brightness of the first region; When the sixth brightness information is less than the first threshold value, the second projector projects the second image onto the second region; When the sixth brightness information is greater than or equal to the second threshold value, the third projector stacks the fifth image on the first image in the first region; The projection method according to claim 6, further comprising:

11. The third projector projects a third image onto a third region different from the first region and the second region; Detecting the presence or absence of a person in a first monitoring region including the first region; When the person exists in the first monitoring region, obtaining the first brightness information; When the first brightness information is greater than or equal to a second threshold value greater than the first threshold value, in the first region, the third projector stacks the fifth image identical to the first image on the first image; The projection method according to claim 2, further comprising:

12. When the person does not exist in the first monitoring region, detecting the presence or absence of a person in a second monitoring region including the second region; When the person exists in the second monitoring region, obtaining second brightness information indicating the brightness of the second region; When the second brightness information is greater than or equal to the second threshold value, in the second region, the first projector stacks the eighth image identical to the second image on the second image; When the second brightness information is greater than or equal to the second threshold value, in the second region, the third projector stacks the sixth image identical to the second image on the second image; The projection method according to claim 11, further comprising:

13. A sensor that outputs a signal indicating the brightness of the first area; Projecting a first image onto the first area; Obtaining first brightness information indicating the brightness of the first area based on the signal output from the sensor; A first projector that performs the above; A second projector that stacks a fourth image identical to the first image on the first image in the first area when the first brightness information satisfies a first condition; A projection system comprising the above.

14. Causing the first projector to project a first image onto a first area; Causing the second projector to project a second image onto a second area different from the first area; Obtaining first brightness information indicating the brightness of the first area; When the first brightness information satisfies a first condition, causing the second projector to stack a fourth image identical to the first image on the first image in the first area; A program for causing a computer to execute the above.

Images