Projection device and shape correction method

Abstract

The present invention provides a projection device and a shape correction method that can correct the shape of a projected image projected by a rotating projection device into a rectangle, in accordance with the rotation of the projection device. [Solution] The projection device 1 acquires a first rotation angle of the projector 200 rotated up to measurement time T1 based on the output of a distance sensor, and at measurement time T2, which is after measurement time T1, acquires a second rotation angle of the projector 200 rotated up to measurement time T2 based on the output of a distance sensor, and includes a processor 180 that calculates the angle of the optical axis direction of the projector 200 with respect to the direction of the normal vector of the projection surface 30 at a predetermined time after measurement time T2 as the target rotation angle based on the initial angle 173, the elapsed time from measurement time T1 to measurement time T2, the first rotation angle and the second rotation angle, and calculates a correction amount to correct the shape of the projected image at the target rotation angle.

Description

Technical Field

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[0001] The present invention relates to a projection device and a shape correction method.

Background Art

[0002] Conventionally, a projection device capable of changing the position of a projection image projected onto a projection surface is known. For example, Patent Document 1 discloses a projector system including a projection unit that projects a projection image onto a screen and a position movement unit that moves the position of the projection image.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the projector system disclosed in Patent Document 1 has a problem that it is necessary to generate movement data for moving the position of the projection image in advance, which increases the time required for creating content including the projection image.

Means for Solving the Problems

[0005] The projection apparatus of this disclosure comprises: a projector for projecting a projection image onto a projection surface; a rotating device for rotating the projector; a sensor; a storage unit that stores the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface as an initial angle in the initial state when the rotating device is stopped; a processor that acquires a first rotation angle achieved by the rotating device from the time the rotating device starts rotating until a first time point based on the output of the sensor; a second rotation angle achieved by the rotating device from the time the rotating device starts rotating until a second time point after the first time point based on the output of the sensor; and calculates a target rotation angle for the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface at a predetermined time point after the second time point, based on the initial angle, the elapsed time from the first time point to the second time point, and the first and second rotation angles, and calculates a correction amount to correct the shape of the projection image at the target rotation angle.

[0006] The shape correction method of the present disclosure is a shape correction method in which a processor acquires a first rotation angle obtained by a rotating device that rotates a projector that projects a projected image onto a projection surface from the time the rotating device starts rotating until a first time point based on the output of a sensor, and at a second time point after the first time point, acquires a second rotation angle obtained by the rotating device from the time the rotating device starts rotating until a second time point based on the output of a sensor, and at the initial state in which the rotating device has stopped, the processor calculates the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface at a predetermined time point after the second time point as a target rotation angle based on the initial angle which is the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface, the elapsed time from the first time point to the second time point, and the first rotation angle and the second rotation angle, and calculates a correction amount to correct the shape of the projected image at the target rotation angle. [Brief explanation of the drawing]

[0007] [Figure 1]A diagram showing the configuration of the system, including the projection device. [Figure 2] Perspective view of the projection device. [Figure 3] A diagram showing the configuration of a projector. [Figure 4] A diagram showing the relationship between the elapsed time since the start of rotation and the angle of rotation. [Figure 5] A flowchart illustrating the operation of the projection device. [Figure 6] A diagram showing the relationship between the elapsed time since the start of rotation and the angle of rotation. [Modes for carrying out the invention]

[0008] [1. Projection device configuration] Figure 1 shows the system configuration of the system including the projection device 1. This system comprises a projection device 1 and an external device 20 connected via a network 10.

[0009] The external device 20 supplies the projection device 1 with image data that will form the basis of the image displayed on the projection surface 30. The external device 20 can be, for example, a personal computer such as a notebook, desktop, or tablet. Alternatively, a smartphone may be used as the external device 20.

[0010] The projection device 1 comprises a main body 100 and a base 300. The main unit 100 includes a functional unit that realizes the function of projecting an image onto the projection surface 30. The functional unit includes a wireless communication interface 110, an image processing unit 120, a frame memory 125, a remote control receiver 130, a drive unit 140, a sensor unit 150, a projector 200, and a control unit 160. Hereinafter, the interface will be abbreviated as I / F.

[0011] Figure 2 is a perspective view of the projection device 1. The main body 100 is supported on the base 300 by support members 310A and 310B. The base 300 is driven by a drive unit 140 provided in the main body 100 and is configured to rotate 360 ​​degrees clockwise or counterclockwise around the normal vector of the mounting surface on which the projection device 1 is installed.

[0012] For example, the projection surface 30 can be a screen, the wall or ceiling of the room where the projection device 1 is installed, or the exterior wall of a building. In this embodiment, the projection device 1 is configured to change the projection position of the image light projected by the projection device 1 by rotating the base portion 300 with the drive unit 140. For this reason, the projection surface 30 is preferably a room wall or a large screen that has a size that allows the projection device 1 to change the position of the projected light.

[0013] Returning to Figure 1, we will now explain each of the functional components of the main body 100. The wireless communication interface (I / F) 110 is equipped with an interface circuit that supports wireless communication standards such as Bluetooth and Wi-Fi, and is connected to the network 10. The wireless communication interface (I / F) 110 communicates data with external devices 20 via the network 10. Bluetooth and Wi-Fi are registered trademarks.

[0014] The image processing unit 120 receives image data received from the external device 20 via the wireless communication interface 110. A frame memory 125 is connected to the image processing unit 120. The frame memory 125 has multiple banks. Each bank has a storage capacity capable of writing image data for one frame. The frame memory 125 is configured, for example, as SDRAM (Synchronous Dynamic Random Access Memory). The image processing unit 120 expands the image data input from the wireless communication interface 110 into the frame memory 125.

[0015] The image processing unit 120 performs image processing on the image data developed in the frame memory 125. The image processing performed by the image processing unit 120 includes, for example, resolution conversion processing or resizing processing, correction of distortion aberration, shape correction processing, digital zoom processing, adjustment of the color tone and brightness of the image, etc. The image processing unit 120 executes the processing specified by the control unit 160 and performs the processing using the parameters input from the control unit 160 as necessary. Also, the image processing unit 120 can of course execute a combination of a plurality of the above image processes. The image processing unit 120 reads out the image data developed in the bank selected by the control unit 160 from the frame memory 125 and outputs the read image data to the projector 200.

[0016] The image processing unit 120 and the frame memory 125 are constituted by, for example, an integrated circuit. The integrated circuit includes LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), FPGA (Field-Programmable Gate Array), SoC (System-on-a-chip), etc. Also, an analog circuit may be included in a part of the configuration of the integrated circuit, or a configuration in which the control unit 160 and the integrated circuit are combined may be adopted.

[0017] The remote control light receiving unit 130 receives an infrared signal transmitted from the remote control 135. The remote control 135 includes, for example, a plurality of buttons such as a power button, a source switching button, a volume button, a projection start button, a projection end button, a rotation start button for starting the rotation of the pedestal unit 300, and a rotation stop button for ending the rotation of the pedestal unit 300. The remote control 135 transmits an infrared signal corresponding to the button operated by the user to the projection device 1. The remote control light receiving unit 130 outputs an operation signal corresponding to the received infrared signal to the control unit 160. The operation signal is a signal corresponding to the button of the remote control 135 operated by the user.

[0018] The drive unit 140 includes a drive device such as a motor, and is connected to a drive force transmission member such as a gear provided in the pedestal unit 300. By rotating the motor of the drive unit 140 under the control of the control unit 160, the pedestal unit 300 rotates clockwise or counterclockwise with respect to the installation surface on which the projection device 1 is installed. The drive unit 140 and the pedestal unit 300 correspond to a rotating device.

[0019] The sensor unit 150 includes, for example, a distance sensor. The distance sensor is a sensor that measures distance by the ToF (Time of Flight) method. The distance sensor includes a light emitting unit and a light receiving unit. The light emitting unit emits measurement light, and measures the distance between the projection surface 30 and the distance sensor by receiving the reflected light from the projection surface 30 at four light receiving units at the first measurement point, the second measurement point, the third measurement point, and the fourth measurement point. The measurement light may be any of laser light, visible light, ultraviolet light, and infrared light, or measurement waves such as millimeter waves and ultrasonic waves may be used instead of the measurement light. In addition, the sensor unit 150 may be configured to include a gyro sensor that measures the angular velocity of the rotating pedestal unit 300. The sensor unit 150 outputs sensor data indicating the measurement result of the distance sensor to the control unit 160. The sensor data is temporarily stored in the storage unit 170 of the control unit 160. Note that the sensor unit 150 may include a camera instead of the distance sensor. The camera is configured by, for example, a stereo camera, and measures the distance to an object such as the projection surface 30. The camera corresponds to an imaging device.

[0020] FIG. 3 is a diagram showing the configuration of the projector 200. Here, the configuration of the projector 200 will be described while referring to FIG. 3. The projector 200 generates image light by modulating light emitted from the light source 210 using a liquid crystal panel 230, and then projects the generated image light onto an optical unit 250. The projector 200 comprises a light source 210, three liquid crystal panels 230R, 230G, and 230B as light modulation devices, an optical unit 250, and a panel drive unit 270. Hereinafter, the liquid crystal panels 230R, 230G, and 230B of the projector 200 will be collectively referred to as the liquid crystal panel 230.

[0021] The light source 210 includes discharge-type light sources such as ultra-high pressure mercury lamps and metal halide lamps, or solid-state light sources such as light-emitting diodes and semiconductor lasers. Light emitted from the light source 210 is incident on the liquid crystal panel 230. Liquid crystal panels 230R, 230G, and 230B are each composed of transmissive liquid crystal panels in which liquid crystal is sealed between a pair of transparent substrates. Liquid crystal panel 230R modulates red light, liquid crystal panel 230G modulates green light, and liquid crystal panel 230B modulates blue light. Each liquid crystal panel has a pixel region formed therein, consisting of multiple pixels arranged in a matrix, and a driving voltage can be applied to each pixel of the liquid crystal.

[0022] Image data processed by the image processing unit 120 is input to the panel drive unit 270. The panel drive unit 270 applies a drive voltage corresponding to the input image data to each pixel in the pixel area, setting each pixel to a light transmittance corresponding to the image data. Light emitted from the light source 210 is modulated for each pixel as it passes through the pixel areas of the liquid crystal panels 230R, 230G, and 230B, forming image light corresponding to the image data for each color. The formed image light of each color is combined for each pixel by a color synthesis optical system (not shown) to form image light representing a color image. The optical unit 250 includes a projection lens and the like, and projects the image light modulated by the liquid crystal panels 230R, 230G, and 230B onto the projection surface 30.

[0023] Returning to Figure 1, we will continue to explain the configuration of projection device 1. The control unit 160 is a computer device comprising a storage unit 170 and a processor 180.

[0024] The memory unit 170 includes RAM (Random Access Memory) and ROM (Read Only Memory). The RAM stores, for example, sensor data input from the sensor unit 150. The ROM stores control programs 171 that control the operation of the processor 180, initial angles 173, and various setting data.

[0025] The initial angle 173 is angle information calculated by the control unit 160. This angle indicates the angle of the projection lens in the direction of the optical axis with respect to the normal vector direction of the projection surface 30. The initial angle 173 is calculated by the control unit 160 and stored in the storage unit 170, for example, when the projection device 1 is placed on a surface such as a desk.

[0026] The processor 180 is an arithmetic processing unit comprising a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The processor 180 may consist of a single processor or multiple processors. Furthermore, the processor 180 may consist of part or all of the memory unit 170, or an SoC integrated with other circuits. The processor 180 may also consist of a combination of a CPU that executes programs and a DSP (Digital Signal Processor) that performs predetermined arithmetic processing. Additionally, the processor 180 may be configured with all its functions implemented in hardware, or it may be configured using programmable devices.

[0027] [2. Operation of the projection device] When the projection device 1 is placed on a surface such as a desk or table, and the power to the projection device 1 is turned on, the control unit 160 calculates the initial angle 173. The initial angle 173 is the angle between the line vector of the projection surface 30 and the optical axis direction of the projection lens before the drive unit 140 is driven and the rotation of the base unit 300 begins.

[0028] The control unit 160 calculates an initial angle 173, which is the angle between the line vector of the projection surface 30 and the optical axis direction of the projection lens, based on the image captured by the camera equipped in the sensor unit 150. When calculating this initial angle 173, the control unit 160 may have the projector 200 project a predetermined image onto the projection surface 30. The control unit 160 analyzes the captured image of the predetermined image to calculate the initial angle 173. The predetermined image is, for example, an image in which circular or rectangular shapes are placed at predetermined positions on the predetermined image. When the base unit 300 of the projection device 1 does not rotate and the projection device 1 is stationary, this angle can be calculated accurately by calculating the angle between the normal vector of the projection surface 30 and the optical axis direction of the projection lens based on the image captured by the camera.

[0029] Next, when the user presses the rotation start button on the remote control 135, the control unit 160 drives the base unit 300 via the drive unit 140, causing the projection device 1 to rotate relative to the mounting surface.

[0030] When the base unit 300 starts rotating relative to the installation surface, the control unit 160 causes the distance sensor to start measuring distance. The distance sensor measures the distance to multiple measurement points on the projection surface 30 and outputs sensor data indicating the measurement results to the control unit 160. For example, the distance sensor outputs sensor data indicating the measurement results for four measurement points: the first measurement point, the second measurement point, the third measurement point, and the fourth measurement point. For example, the first measurement point is a position on the projection surface 30 moved by +θ degrees horizontally and +θ degrees vertically from the optical axis direction of the projection lens. The second measurement point is a position on the projection surface 30 moved by -θ degrees horizontally and +θ degrees vertically from the optical axis direction of the projection lens. The third measurement point is a position on the projection surface 30 moved by +θ degrees horizontally and -θ degrees vertically from the optical axis direction of the projection lens. The fourth measurement point is a position on the projection surface 30 moved by -θ degrees horizontally and -θ degrees vertically from the optical axis direction of the projection lens. The control unit 160 temporarily stores the sensor data input from the distance sensor in the storage unit 170.

[0031] The control unit 160 acquires sensor data from the storage unit 170. The sensor data acquired by the control unit 160 is called sensor data D1. It is assumed that sensor data D1 is data measured after measurement time T1 from the time the base unit 300 starts rotating. Measurement time T1 corresponds to the first time point. The control unit 160 calculates the distance between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30 based on the acquired sensor data D1. Based on the calculated distances between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30, the control unit 160 calculates the rotation angle, which indicates the amount of rotation of the base unit 300 from the time the base unit 300 starts rotating until measurement time T1 has elapsed. This rotation angle is denoted as the first rotation angle α1.

[0032] Next, the control unit 160 acquires sensor data again from the storage unit 170. At this time, the sensor data acquired by the control unit 160 is called sensor data D2. It is assumed that sensor data D2 is data measured after measurement time T2 from the time the base unit 300 starts rotating. Measurement time T2 corresponds to the second time point. The control unit 160 calculates the distance between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30 based on the acquired sensor data D2. Based on the calculated distances between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30, the control unit 160 calculates the rotation angle, which indicates the amount of rotation of the base unit 300 from the time the base unit 300 starts rotating until measurement time T2 has elapsed. This rotation angle is denoted as the second rotation angle α2.

[0033] Figure 4 shows the relationship between the elapsed time since the start of measurement and the amount of rotation of the base portion 300. Next, the control unit 160 calculates the target rotation angle, which is the angle between the optical axis of the projection lens and the normal vector of the projection surface 30 at a predetermined time T(n) that will occur from now on. The target rotation angle at the predetermined time T(n) is denoted as angle α(n), where n is a natural number greater than or equal to 3. The predetermined time T(n) corresponds to a predetermined point in time.

[0034] First, the control unit 160 calculates the rotation angle, which is the amount of rotation of the main body 100 per unit time. The control unit 160 calculates the difference between the first rotation angle α1 and the second rotation angle α2, and the elapsed time from measurement time T1 to measurement time T2. The control unit 160 divides the calculated difference in rotation angles by the elapsed time to calculate the rotation angle per unit time of the main unit 100.

[0035] Next, the control unit 160 calculates the target rotation angle α(n) at a predetermined time T(n). The control unit 160 calculates the target rotation angle α(n) at a predetermined time T(n) based on the initial angle 173, the calculated rotation angle per unit time, and the predetermined time T(n).

[0036] Next, the control unit 160 calculates a correction parameter C(n) to correct the image data so that the shape of the image displayed on the projection surface 30 becomes rectangular, when the angle between the optical axis of the projection lens and the normal vector of the projection surface 30 is the target rotation angle α(n). The correction parameter C(n) corresponds to the correction amount.

[0037] Subsequently, the control unit 160 instructs the image processing unit 120 to correct the shape of the image data using the calculated correction parameter C(n), and at a predetermined time T(n), projects image light based on the shape-corrected image data onto the projection surface 30 using the projector 200. As a result, at the predetermined time T(n), a rectangular image is projected onto the projection surface 30.

[0038] Next, the control unit 160 increments the value of n by 1 to calculate the target rotation angle α(n+1) for a predetermined time T(n+1). The control unit 160 also calculates a correction parameter C(n+1) to correct the image data so that the shape of the image displayed on the projection surface 30 becomes rectangular when the angle between the optical axis of the projection lens and the normal vector of the projection surface 30 is the target rotation angle α(n+1). The interval between the predetermined time Tn and the predetermined time T(n+1) can be set arbitrarily. For example, it may be set by the user operating the remote control 135, or it may be set based on the performance of the processor 180.

[0039] The control unit 160 continues this process until the rotation stop button on the remote control 135 is pressed.

[0040] Figure 5 is a flowchart showing the operation of projection device 1. The operation of projection device 1 will be explained with reference to the flowchart shown in Figure 5. When the power to the projection device 1 is turned on (step S1), the control unit 160 calculates the initial angle 173 (step S2). The control unit 160 displays a predetermined image on the projection surface 30 using the projector 200 and causes the camera in the sensor unit 150 to perform imaging to acquire the captured image. The control unit 160 performs image analysis on the acquired captured image to calculate the initial angle 173, which is the angle between the normal vector of the projection surface 30 and the optical axis direction of the projection lens.

[0041] Next, the control unit 160 determines whether or not the rotation start button has been pressed (step S3). For example, the control unit 160 determines that it has received a rotation instruction by detecting that the rotation start button on the remote control 135 has been pressed. If the rotation start button has not been pressed (step S3 / NO), the control unit 160 waits until it receives a rotation instruction.

[0042] When the rotation start button is pressed (step S3 / YES), the control unit 160 drives the drive unit 140 to start the rotation of the base unit 300 (step S4).

[0043] Next, the control unit 160 instructs the distance sensor to measure the distance (step S5). The control unit 160 then temporarily stores the sensor data sequentially input from the distance sensor in the storage unit 170.

[0044] Next, the control unit 160 acquires sensor data D1 measured at measurement time T1 from the storage unit 170 (step S6). Based on the acquired sensor data D1, the control unit 160 acquires the distances to the first measurement point, second measurement point, third measurement point, and fourth measurement point, respectively (step S7). Then, based on the calculated distances between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30, the control unit 160 calculates the first rotation angle α1 that the base unit 300 has rotated from the time the base unit 300 started rotating until measurement time T1 has elapsed (step S8).

[0045] Next, the control unit 160 acquires sensor data D2 from the storage unit 170 (step S9). Based on the acquired sensor data D2, the control unit 160 calculates the distances between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30 (step S10). Then, based on the calculated distances between the first measurement point, second measurement point, third measurement point, and fourth measurement point and the projection surface 30, the control unit 160 calculates the second rotation angle α2 of the base unit 300 from the time the base unit 300 starts rotating until measurement time T2 has elapsed (step S11).

[0046] Next, the control unit 160 calculates the target rotation angle α(n), which is the angle between the optical axis of the projection lens and the normal vector of the projection surface 30 at a predetermined time T(n) (step S12).

[0047] The control unit 160 calculates a correction parameter Cn to correct the image data so that the shape of the image displayed on the projection surface 30 becomes rectangular, when the angle between the optical axis of the projection lens and the normal vector of the projection surface 30 is the target rotation angle α(n) (step S13).

[0048] The control unit 160 instructs the image processing unit 120 to correct the shape of the image data using the calculated correction parameter C(n). The control unit 160 determines whether the current time has reached the predetermined time T(n) (step S14). If the current time has not reached the predetermined time T(n) (step S14 / NO), the control unit 160 waits until the current time reaches the predetermined time T(n).

[0049] When the current time reaches a predetermined time T(n) (step S14 / YES), the control unit 160 causes the projector 200 to project image light based on the corrected image data according to the correction parameter C(n) onto the projection surface 30 (step S15). As a result, at the predetermined time T(n), a rectangular image is projected onto the projection surface 30.

[0050] Next, the control unit 160 determines whether or not it has received an operation on the rotation stop button to terminate the rotation of the base unit 300 (step S16). If the control unit 160 has not received an operation on the rotation stop button (step S16 / NO), it increments the value of n by 1 (step S17) and returns to the process in step S12.

[0051] Furthermore, when the control unit 160 receives an operation of the rotation stop button to terminate the rotation of the base unit 300 (step S16 / YES), it stops the drive of the drive unit 140 to stop the rotation of the base unit 300, and terminates this processing flow.

[0052] [3. Variant] The above explanation described the case where the base portion 300 rotates at a constant speed, but it is also possible for the rotational speed of the base portion 300 to accelerate. Figure 6 shows the angles α1 at measurement time T1, α2 at measurement time T2, and α3 at measurement time T3. Angle α1 is the angle calculated from sensor data D1 measured at measurement time T1. Angle α2 is the angle calculated from sensor data D2 measured at measurement time T2. Angle α3 is the angle calculated from sensor data D3 measured at measurement time T3. Measurement time T3 corresponds to the third time point.

[0053] As shown in Figure 6, the control unit 160 calculates a quadratic approximation curve based on the measurement times T1, T2, and T3 and the calculated angles α1, α2, and α3. The control unit 160 substitutes the measurement time T(n) into the calculated quadratic approximation curve and calculates the angle α(n) at measurement time T(n). The subsequent operations are the same as those of the embodiment described above.

[0054] Each of the embodiments described above is a preferred embodiment of the present invention. However, the invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

[0055] Furthermore, the functional units of the projection device 1 shown in Figure 1 represent a functional configuration, and the specific implementation form is not particularly limited. In other words, it is not necessarily required that hardware corresponding to each functional unit be implemented individually, and it is certainly possible to have a configuration in which a single processor executes a program to realize the functions of multiple functional units. Also, in the above embodiment, some of the functions realized by software may be realized by hardware, and vice versa.

[0056] Furthermore, the processing units in the flowchart shown in Figure 5 are divided according to the main processing content in order to facilitate understanding of the operation of the projection device 1, and the present invention is not limited by the way the processing units are divided or the names of the processing units shown in the flowchart in Figure 5. In addition, the processing of the projection device 1 can be further divided into many more processing units depending on the processing content, or it can be divided so that one processing unit contains even more processing. Also, the processing order in the flowchart above is not limited to the example shown.

[0057] Furthermore, while Figure 3 shows a configuration in which the projector 200 is equipped with transmissive liquid crystal panels 230R, 230G, and 230B, the optical modulator may, for example, be configured using three reflective liquid crystal panels, or a system combining one liquid crystal panel and a color wheel may be used. Alternatively, it may be configured using a system with three digital mirror devices, or a DMD system combining one digital mirror device and a color wheel. When using only one liquid crystal panel or DMD as the optical modulator, components equivalent to a composite optical system such as a cross dichroic prism are not required. In addition, any optical modulator capable of modulating light emitted from a light source can be used without any problems, other than liquid crystal panels and DMDs.

[0058] Furthermore, when the program of this disclosure is to be executed by the processor 180 of the projection device 1, the program to be executed by the processor 180 can also be configured as a recording medium. Alternatively, the program to be executed by the processor 180 can also be configured as a transmission medium for transmitting the program. Magnetic, optical, or semiconductor memory devices can be used as the recording medium. Specifically, examples include portable or fixed recording media such as flexible disks, HDDs, CD-ROMs (compact disc read-only memory), DVDs (Digital Versatile Discs), Blu-ray Discs, magneto-optical disks, flash memory, and card-type recording media. The above recording media may also be non-volatile storage devices such as RAM, ROM, and HDDs, which are internal storage devices of server equipment. Blu-ray is a registered trademark.

[0059] [Summary of the 4 disclosures] A summary of this disclosure is provided below.

[0060] (Note 1) A projection device comprising: a projector for projecting an image onto a projection surface; a rotating device for rotating the projector; a sensor; a storage unit that stores the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface as an initial angle when the rotating device is stopped; a processor that acquires a first rotation angle based on the output of the sensor between the time the rotating device starts rotating and the first time point, acquires a second rotation angle based on the output of the sensor between the time the rotating device starts rotating and the second time point, calculates the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface at a predetermined time point after the second time point as a target rotation angle, and calculates a correction amount to correct the shape of the projected image at the target rotation angle, based on the initial angle, the elapsed time from the first time point to the second time point, the first rotation angle and the second rotation angle.

[0061] According to the projection device described in Appendix 1, the angle of the optical axis direction of the projector relative to the direction of the normal vector of the projection surface at a predetermined time is calculated as the target angle based on the first rotation angle at a first time point and the second rotation angle at a second time point, which are acquired based on the sensor output, the elapsed time from the first time point to the second time point, and the initial angle. Then, a correction amount is calculated to correct the shape of the projected image at the calculated target angle, and the shape of the projected image is corrected by the calculated correction amount, and the projected image with the corrected shape is projected at the predetermined time point. As a result, a rectangular projected image can be projected onto the projection surface at the predetermined time point. In other words, the shape of the projected image can be corrected to a rectangle in accordance with the rotation of the projection device, thereby increasing user satisfaction.

[0062] (Note 2) The projection device as described in Appendix 1 includes a Time of Flight (ToF) sensor that measures the distance to multiple points on the projection surface, and the processor obtains a first rotation angle and a second rotation angle based on the distance measurement results to multiple points measured by the ToF sensor.

[0063] According to the projection device described in Appendix 2, the first and second rotation angles are obtained based on the distance measurement results to multiple points on the projection surface measured by the ToF sensor. Therefore, accurate first and second rotation angles can be obtained.

[0064] (Note 3) The projection apparatus as described in Appendix 1, wherein the sensor includes an imaging device that captures an image of the projection surface, and the processor, in its initial state, calculates the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface as the initial angle based on the image captured by the imaging device.

[0065] According to the projection device described in Appendix 3, the angle of the projector's optical axis relative to the direction of the normal vector of the projection surface is calculated based on the image captured by the imaging device. Therefore, the angle of the projector's optical axis relative to the direction of the normal vector of the projection surface can be calculated with high accuracy.

[0066] (Note 4) The projection apparatus as described in Appendix 1, wherein the processor, at a third time point following the second time point, obtains the third rotation angle achieved by the rotating device between the start of rotational operation and the third time point based on the sensor output, calculates a quadratic approximation curve based on the initial angle, the elapsed time from the first time point, the second time point, and the third time point, and the first rotation angle, the second rotation angle, and the third rotation angle, calculates the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface at a predetermined time point as the target rotation angle, and calculates a correction amount to correct the shape of the projected image at the target rotation angle.

[0067] According to the projection device described in Appendix 4, a quadratic approximation curve is determined based on the first rotation angle at the first time point, the second rotation angle at the second time point, and the third rotation angle at the third time point, all acquired based on the sensor output, along with the elapsed time from the initial state to the first, second, and third time points, and the initial angle. Based on the determined quadratic approximation curve, the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface at a predetermined time point is calculated as the target angle. Then, a correction amount is calculated to correct the shape of the projected image at the calculated target angle, and the shape of the projected image is corrected using the calculated correction amount, so that the corrected image is projected at the predetermined time point. As a result, a rectangular projection image can be projected onto the projection surface at a predetermined time point.

[0068] (Note 5) A shape correction method comprising: a processor acquiring a first rotation angle based on sensor output from the time a rotating device that rotates a projector that projects an image onto a projection surface starts rotating until the first time point; acquiring a second rotation angle based on sensor output from the time a rotating device starts rotating until the second time point after the first time point; calculating a target rotation angle based on the initial angle, which is the angle of the optical axis direction of the projector with respect to the direction of the normal vector of the projection surface, in the initial state when the rotating device has stopped, the elapsed time from the first time point to the second time point, and the first and second rotation angles; and calculating a correction amount to correct the shape of the projected image at the target rotation angle.

[0069] According to the shape correction method described in Appendix 5, the angle of the optical axis direction of the projector relative to the direction of the normal vector of the projection surface at a predetermined time is calculated as the target angle based on the first rotation angle at the first time point and the second rotation angle at the second time point, which are acquired based on the sensor output, the elapsed time from the first time point to the second time point, and the initial angle. Then, a correction amount is calculated to correct the shape of the projected image at the calculated target angle, and the shape of the projected image is corrected by the calculated correction amount, and the projected image with the corrected shape is projected at the predetermined time point. As a result, a rectangular projected image can be projected onto the projection surface at the predetermined time point. In other words, the shape of the projected image can be corrected to a rectangle in accordance with the rotation of the projection device, thereby increasing user satisfaction. [Explanation of Symbols]

[0070] 1...Projection device, 10...Network, 20...External device, 30...Projection surface, 100...Main unit, 110...Wireless communication interface, 120...Image processing unit, 125...Frame memory, 130...Remote control receiver, 135...Remote control, 140...Drive unit, 150...Sensor unit, 160...Control unit, 170...Storage unit, 171...Control program, 173...Initial angle, 180...Processor, 200...Projector, 210...Light source, 230...Liquid crystal panel, 230B...Liquid crystal panel, 230G...Liquid crystal panel, 230R...Liquid crystal panel, 250...Optical unit, 270...Panel drive unit, 300...Base unit, 310A...Support member, 310B...Support member, Cn...Correction parameter, D1...Sensor data, D2...Sensor data, D3...Sensor data.

Claims

1. A projector that projects an image onto a projection surface, A rotating device for rotating the aforementioned projector, Sensors and A storage unit that stores the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface as the initial angle when the rotating device is stopped, Between the time the rotating device starts rotating and the first time point, the first rotation angle achieved by the rotating device is obtained based on the output of the sensor. At a second time point following the first time point, the second rotation angle achieved by the rotating device between the start of rotation and the second time point is obtained based on the output of the sensor. Based on the initial angle, the elapsed time from the first time point to the second time point, and the first and second rotation angles, the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface at a predetermined time point after the second time point is calculated as the target rotation angle. A processor that calculates a correction amount to correct the shape of the projected image at the target rotation angle, A projection device equipped with the following features.

2. The sensor includes a Time of Flight (ToF) sensor that measures the distance to multiple points on the projection surface. The projection apparatus according to claim 1, wherein the processor acquires the first rotation angle and the second rotation angle based on the measurement results of the distance to the plurality of points measured by the ToF sensor.

3. The sensor includes an imaging device that captures the projection surface, The projection apparatus according to claim 1, wherein the processor, in the initial state, calculates the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface, based on the image captured by the imaging device, as the initial angle.

4. The aforementioned processor, At a third time point, which occurs after the second time point, the third rotation angle achieved by the rotating device between the start of rotation and the third time point is obtained based on the output of the sensor. A quadratic approximation curve is obtained based on the initial angle, the elapsed time up to the first, second, and third time points, and the first, second, and third rotation angles. Based on the obtained quadratic approximation curve, the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface at the predetermined time is calculated as the target rotation angle. The projection device according to claim 1, which calculates a correction amount for correcting the shape of the projected image at the target rotation angle.

5. The processor The first rotation angle achieved by the rotating device that rotates the projector that projects an image onto the projection surface, from the time the rotating device starts rotating until the first time point, is acquired based on the output of the sensor. At a second time point following the first time point, the second rotation angle achieved by the rotating device between the start of rotation and the second time point is obtained based on the output of the sensor. In the initial state when the rotating device is stopped, the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface is calculated as the target rotation angle based on the initial angle, which is the angle in the direction of the optical axis of the projector with respect to the direction of the normal vector of the projection surface, the elapsed time from the first time point to the second time point, and the first rotation angle and the second rotation angle. A correction amount is calculated to correct the shape of the projected image at the target rotation angle. Shape correction method.

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