Projection device, method of adjusting the same, and program

Abstract

To provide a projection device which allows the size and brightness of multiple projected dots to be easily adjusted, and to provide a method of adjusting the same and a program.SOLUTION: A projection device is provided, comprising a light source for emitting laser light, a diffractive optical element for converting the laser light entering from the light source into dot pattern light that allows multiple dots with a diameter corresponding to a beam diameter of the laser light to be formed on a projection target, and an optical system located in an optical path of the laser light between the light source and the diffractive optical element and configured to be capable of changing the beam diameter of the laser light entering the diffractive optical element.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a projection device, a method for adjusting a projection device, and a program. [Background technology]

[0002] Conventionally, there are projection devices that diffract and split laser light using a diffractive optical element to project a predetermined image pattern onto a projection target such as a screen. For example, Patent Document 1 discloses a projection device that can project a linear pattern using a diffractive optical element. By adjusting the shape of the diffraction grating, it is also possible to project an image pattern consisting of multiple dots. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-43061 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional technology has a problem in that it is not easy to adjust the size and brightness of the multiple dots that are projected.

[0005] An object of the present invention is to make it possible to easily adjust the size and brightness of a plurality of projected dots. [Means for solving the problem]

[0006] In order to solve the above problems, a projection device according to the present invention comprises: a light source that emits laser light; a diffractive optical element that converts the laser light incident from the light source into dot pattern light that can form a plurality of dots having a diameter corresponding to the beam diameter of the laser light on a projection target; an optical system that is arranged in an optical path of the laser light between the light source and the diffractive optical element and that is capable of changing the beam diameter of the laser light that is incident on the diffractive optical element; Equipped with. [Effects of the Invention]

[0007] According to the present invention, the size and brightness of the projected dots can be easily adjusted. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a projection device. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the projection device. [Figure 3] FIG. 2 is a schematic diagram illustrating a configuration of an image projection unit. [Figure 4] 4(a) and 4(b) are schematic diagrams showing the configuration of the optical system. [Figure 5] FIG. 2 is a diagram illustrating a lens movement mechanism in an optical system. [Figure 6] FIG. 2 is a diagram illustrating a configuration of a diffractive optical element. [Figure 7] FIG. 10 is a schematic diagram showing the image projection unit when the beam diameter is increased. [Figure 8] FIG. 10 is a diagram showing a dot pattern. [Figure 9] FIG. 2 is a diagram showing an image area and a light-blocking area in a display element. [Figure 10] 9A and 9B are diagrams showing the dot pattern of FIG. 8 and the image pattern projected by the display element of FIG. [Figure 11] FIG. 10 is a diagram showing a dot pattern when the beam diameter is increased. [Figure 12] 10A and 10B are diagrams illustrating other examples of image areas and light-blocking areas in a display element. [Figure 13] 13 is a diagram showing the dot pattern of FIG. 11 and the image pattern projected by the display element of FIG. 12. [Figure 14] 10 is a flowchart showing a control procedure for projection processing. [Figure 15] 10 is a flowchart showing a control procedure for projection processing. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a projection device 1 of this embodiment projects image light L3 onto a projection target 2, thereby displaying (projecting) various images onto the surface of the projection target 2. The projection target 2 may be, for example, a screen, a wall, floor, or ceiling of a building, or the surface of any object. In this embodiment, the distance d from the projection device 1 to the projection target 2 is approximately 2 m, but is not limited to this. The image projected onto the surface of the projection target 2 is not particularly limited, and may be, for example, an image of a guide sign for guiding people in the vicinity, or an image for decorating the surface of the projection target 2.

[0010] 2, the projection device 1 includes a CPU 11 (Central Processing Unit) (control unit, control means), a RAM 12 (Random Access Memory), a storage unit 13, a distance sensor 20, and an image projection unit 30. The components of the projection device 1 are connected via a data transmission path such as a bus. The projection device 1 may further include components not shown in FIG. 2, such as an operation unit that accepts input operations from a user, a display unit that displays status information of the projection device 1, and a communication unit that communicates with external devices.

[0011] The CPU 11 is a processor that controls the operation of the projection device 1 by reading and executing a program 131 stored in the storage unit 13 and performing various arithmetic processing. The projection device 1 may have multiple processors (for example, multiple CPUs), and the multiple processes performed by the CPU 11 of this embodiment may be executed by these multiple processors. In this case, the multiple processors form a control unit. In this case, the multiple processors may be involved in a common process, or the multiple processors may independently execute different processes in parallel. The RAM 12 provides a working memory space for the CPU 11 and stores temporary data.

[0012] The storage unit 13 is a non-transitory recording medium readable by the CPU 11 as a computer, and stores a program 131 and various data. The storage unit 13 includes a non-volatile memory such as a hard disk drive (HDD) or a solid state drive (SSD). The program 131 is stored in the storage unit 13 in the form of a computer-readable program code. Data stored in the storage unit 13 includes image data 132 used to project the image light L3, a beam diameter setting table referred to when adjusting the beam diameter B described below, and the like. In this embodiment, the image data 132 is data in which each pixel has one of two pixel values.

[0013] As shown in Fig. 1, the distance sensor 20 measures the distance d from the projection device 1 to the projection target 2. The distance sensor 20 of this embodiment detects the distance using a TOF (Time Of Flight) method. The TOF distance sensor 20 includes a light-emitting unit and a light-receiving unit, and detects the distance to the projection target 2 based on the time it takes for inspection light irradiated from the light-emitting unit to be reflected by the projection target 2 and return to the light-receiving unit. Note that the distance measurement method of the distance sensor 20 is not limited to the TOF method, and other methods such as a stereo method may also be used.

[0014] As shown in FIGS. 2 and 3, the image projection unit 30 includes a light source 31, an optical system driver 32 (driver), an optical system 33, a diffractive optical element 34 (DOE), and a display element 35. The light source 31 emits linear laser light L1 in the visible wavelength range toward the optical system 33. The light source 31 includes a semiconductor light-emitting element such as a laser diode, and a collimator lens that focuses the laser light output from the semiconductor light-emitting element into linear parallel light. Below, the positions and operations of each part of the image projection unit 30 will be described using an XYZ Cartesian coordinate system in which the optical axis of the laser light L1 is the Z axis. The traveling direction of the laser light L1 is defined as the +Z direction.

[0015] The optical system 33 is disposed in the optical path of the laser light L1 between the light source 31 and the diffractive optical element 34. As shown in FIGS. 4(a) and 4(b), the optical system 33 has a plurality of lenses, and by changing the positions of at least some of the lenses in the optical axis direction, the beam diameter B of the laser light L1 incident on the diffractive optical element 34 can be changed. The optical system 33 of this embodiment has a first convex lens 331, a second convex lens 332, and a concave lens 333 arranged in order in the +Z direction. By changing the positions of the second convex lens 332 and the concave lens 333, the beam diameter B of the laser light L1 can be changed. For example, by moving the second convex lens 332 in the +Z direction and the concave lens 333 in the −Z direction from the state shown in FIG. 4(a), the beam diameter B can be increased. Furthermore, by moving the second convex lens 332 and the concave lens 333 in the opposite direction, the beam diameter B can be decreased.

[0016] The movements of these lenses can be realized, for example, by the mechanism shown in FIG. 5 . The optical system 33 includes a cam barrel 41, an inner barrel 42 disposed inside the cam barrel 41, a movable barrel 43 to which a second convex lens 332 is attached and which moves inside the inner barrel 42 in the optical axis direction, and a movable barrel 44 to which a concave lens 333 is attached and which moves inside the inner barrel 42 in the optical axis direction. For ease of explanation, FIG. 5 illustrates the inner barrel 42 pulled out from the cam barrel 41. The cam barrel 41 is provided with cam grooves 411 and 412 that extend obliquely with respect to the optical axis direction. The cam groove 411 is provided so that the position of the groove changes clockwise as it moves toward the +Z direction, and the cam groove 412 is provided so that the position of the groove changes counterclockwise as it moves toward the +Z direction. The inner barrel 42 is provided with a linear groove 421 that extends in the optical axis direction. A cam follower 431 is provided on the outer surface of movable barrel 43, passing through linear groove 421 and cam groove 411 and movable along these grooves. A cam follower 441 is provided on the outer surface of movable barrel 44, passing through linear groove 421 and cam groove 412 and movable along these grooves. For ease of explanation, in Figure 5, movable barrels 43 and 44 are depicted separately from cam barrel 41 and inner barrel 42.

[0017] When the inner barrel 42, movable barrel 43, and movable barrel 44 are stored inside the cam barrel 41 and the movement of the cam barrel 41 and inner barrel 42 in the Z direction is restricted, and the cam barrel 41 is rotated counterclockwise as viewed from the light source 31, the position of the intersection between the cam groove 411 and the linear groove 421 moves in the +Z direction. Because the cam follower 431 is always positioned at the intersection between the cam groove 411 and the linear groove 421, the cam follower 431 moves in the +Z direction as the intersection moves, and this causes the movable barrel 43 and the second convex lens 332 to move in the +Z direction. Furthermore, when the cam barrel 41 is rotated counterclockwise as viewed from the light source 31, the position of the intersection between the cam groove 412 and the linear groove 421 moves in the -Z direction. Since cam follower 441 is always positioned at the intersection of cam groove 412 and linear groove 421, at this time cam follower 441 moves in the -Z direction in accordance with the movement of the intersection, which causes movable barrel 44 and concave lens 333 to move in the -Z direction. On the other hand, when cam barrel 41 is rotated clockwise as viewed from light source 31, movable barrel 43 and movable barrel 44 move in the direction opposite to the above.

[0018] 2 drives the optical system 33 so as to change the beam diameter B of the laser light L1 incident on the diffractive optical element 34. The optical system driver 32 has a motor (not shown) that rotates the cam barrel 41, and rotates the cam barrel 41 in a direction and by an amount according to a control signal transmitted from the CPU 11. As a result, the second convex lens 332 and the concave lens 333 move in the optical axis direction by a distance according to the direction and amount of rotation of the cam barrel 41, thereby changing the beam diameter B of the laser light L1.

[0019] The diffractive optical element 34 is a light-transmitting plate-like member on which a diffraction grating having a fine concave-convex structure is formed. The diffractive optical element 34 is positioned so that the surface of the diffraction grating is perpendicular to the optical axis of the laser light L1. The diffractive optical element 34 transmits the laser light L1 incident from the light source 31 and diffracts the laser light L1 using the diffraction grating, thereby converting the laser light L1 into the dot pattern light L2 shown in FIG. 3. The dot pattern light L2 is composed of multiple branched beams traveling in different directions. In other words, the diffraction grating of the diffractive optical element 34 has a concave-convex structure adjusted so that the diffracted beams of the laser light L1 constructively interact with each other at the positions of the branched beams. In this way, the diffractive optical element 34 functions as a transmissive beam splitter that splits the laser light L1 into multiple branched beams. Each branched beam can form dots D (see FIG. 8) on the projection target 2, each having a diameter corresponding to the beam diameter B of the laser light L1. Specifically, when the dot pattern light L2 is not blocked by the display element 35, it can form multiple dots D corresponding to the multiple branched beams on the projection target 2. The dot pattern light L2 of this embodiment can form a dot pattern DP consisting of a plurality of dots D arranged in a matrix along the X and Y directions as shown in Fig. 8. The diameter dD of each dot D formed by the dot pattern light L2 is approximately constant regardless of the distance d from the projection device 1 to the projection target 2. The diameter dD of a dot D refers to the diameter of a circular area having a brightness that is 10% or more of the central brightness of the dot D. On the other hand, the arrangement pitch pD of the dots D in the dot pattern DP increases as the distance d increases.

[0020] As shown in FIG. 6, the diffractive optical element 34 of this embodiment has a structure in which a plurality of unit cells 341 are arranged in a matrix along the XY plane. Each unit cell 341 is the smallest unit that functions as a beam splitter that splits the laser light L1 into a plurality of branched beams corresponding to the dot pattern DP. In other words, the unit cell 341 is the smallest unit of a diffraction grating capable of forming the dot pattern DP. Therefore, when the beam diameter B of the incident laser light L1 is increased (for example, when the beam diameter is changed from B1 to B2 in FIG. 6), the laser light L1 is incident on more unit cells 341, and branched beams are generated by the action of each unit cell 341 into which the laser light L1 is incident, thereby forming the dot pattern DP. The thickness of each branched beam generated in this case is the combined thickness of the branched beams generated by adjacent unit cells 341. For example, when a dot pattern light L2 having the width shown in FIG. 3 is generated by a laser beam L1 having a beam diameter B1 shown in FIG. 6, if the beam diameter B of the laser beam L1 is changed to a larger value, such as the beam diameter B2 shown in FIG. 6, each branched beam of the dot pattern light L2 generated by the diffractive optical element 34 will be thicker, as shown in FIG. 7. A dot D formed by this branched beam has a size equal to the size of small dots formed by adjacent unit cells 341 that are united. Therefore, the diameter dD of each dot D is approximately equal to the beam diameter B of the laser beam L1 incident on the diffractive optical element 34. Furthermore, the area of ​​each dot D is approximately equal to the area of ​​the unit cell 341 into which the laser beam L1 is incident (hence, approximately equal to the cross-sectional area perpendicular to the optical axis of the incident laser beam L1). However, the diameter dD of the dot D does not necessarily have to be approximately equal to the beam diameter B of the laser beam L1, and may be another size according to the beam diameter B.

[0021] The display element 35 shown in FIG. 2 is a transmissive liquid crystal display element arranged perpendicular to the optical axis of the laser light L1 on the +Z direction side of the diffractive optical element 34. The above-mentioned dot pattern light L2 is incident on the display element 35. The display element 35 includes a dot-matrix liquid crystal panel in which pixels are arranged in a matrix, polarizers arranged on both sides of the liquid crystal panel, and a liquid crystal drive circuit for driving the liquid crystal panel. The liquid crystal drive circuit controls the alignment state of the liquid crystal layer of each pixel by applying a drive voltage to each pixel corresponding to the image to be displayed (corresponding to the pixel value of the pixel in the image data 132) based on a control signal and image data 132 transmitted from the CPU 11. Depending on the drive voltage applied, each pixel switches between a state in which light incident on the pixel is transmitted through the polarizer on the output side (ON state) and a state in which light incident on the pixel is absorbed by the polarizer on the output side (OFF state). By distributing the ON state pixels according to the image data 132, an image corresponding to the image data 132 can be displayed in a transmissive manner. For example, when the display element 35 is driven based on image data 132 relating to the arrow image shown in FIG. 9, pixels in the arrow-shaped image region R1 are turned on, and light incident on the image region R1 is transmitted. Furthermore, pixels in the light-shielding region R2 outside the image region R1 are turned off, and light incident on the light-shielding region R2 is absorbed and shielded. When dot pattern light L2 forming the dot pattern DP shown in FIG. 8 is incident on the display element 35 in this state, only the branched light of the dot pattern light L2 that is incident on the arrow-shaped image region R1 is transmitted, as shown in FIG. 10. The light of the dot pattern light L2 that is transmitted through the display element 35 is image light L3 (see FIG. 3). In this way, the display element 35 generates image light L3 by extracting a portion of the dot pattern light L2 that is incident on the image region R1 based on the image data 132. The image light L3 is projected outside the projection device 1 through a projection port (not shown) provided in the housing of the projection device 1 and onto the projection target 2. As a result, an image pattern IP of FIG. 10 consisting of dots D distributed in the shape of an arrow is projected onto the projection target 2.

[0022] Next, a first method for adjusting the beam diameter B of the laser light L1 in the projection device 1 will be described. As described with reference to FIGS. 8 to 10, the image pattern IP is projected by transmitting only a portion of the dot pattern light L2 that forms the dot pattern DP and that is incident on the image region R1 corresponding to the image data 132 as image light L3. Here, if the image related to the image data 132 has a low level of complexity, as shown by the arrows in FIG. 9, the image pattern IP can be recognized as an arrow-shaped image pattern IP from the distribution positions of the dots D even if the diameter dD of the dots D is small. However, if the complexity of the image related to the image data 132 is too high compared to the number of dots D included in the dot pattern DP, it becomes difficult to properly recognize the outline of the image from the distribution positions of the dots D alone. Here, the image complexity can be, for example, an index that increases as the representative value of the spatial frequency of the image data (image signal) (e.g., the frequency that gives the peak of the spatial frequency spectrum) increases, or an index that increases as the density of the boundary between the image region R1 and the light-blocking region R2 increases.

[0023] Therefore, the CPU 11 of the projection device 1 of this embodiment controls the optical system driver 32 based on the complexity of the image associated with the image data 132 so that the beam diameter B of the laser light L1 increases as the complexity increases. Hereinafter, an example will be described in which an image of a human-shaped pictogram shown in FIG. 12 is used as an image with a higher complexity than the image indicated by the arrow in FIG. 9. In this case, the CPU 11 controls the optical system driver 32 to drive the optical system 33, thereby increasing the beam diameter B of the laser light L1, thereby increasing the diameter dD of the dots D in the dot pattern DP as shown in FIG. 11 compared to that shown in FIG. 8. In the dot pattern DP shown in FIG. 11, adjacent dots D partially overlap. In other words, the diameter dD of the dots D is larger than the arrangement pitch pD.

[0024] When the dot pattern DP shown in Fig. 11 is incident on the display element 35 shown in Fig. 12, the image pattern IP shown in Fig. 13 is projected onto the projection target 2 by the light that has passed through the image region R1 in Fig. 12. In this image pattern IP, the diameter dD of the dots D is increased, so that the proportion of the image pattern IP that is occupied by the dots D is increased, and therefore the outline of the pictogram can be clearly recognized.

[0025] The projection process executed by the CPU 11 to adjust the beam diameter B according to the complexity of the image will be described with reference to the flowchart in Fig. 14. This projection process is started when the user of the projection device 1 performs an operation to instruct projection of an image.

[0026] When the projection process starts, the CPU 11 derives the image complexity of the image data 132 used to project the image pattern IP (step S101). The image complexity can be derived using various known analytical methods. For example, a method may be used in which the spatial frequency spectrum of the image data (image signal) is obtained by Fourier transform, and the complexity is derived so that the higher the representative value of the spatial frequency (e.g., the frequency that gives the peak of the spatial frequency spectrum) is, the higher the complexity. Alternatively, a method may be used in which boundaries between light and dark regions in a binary image are detected, and the complexity is derived so that the higher the density of the boundaries is, the higher the complexity. The boundary density may be the ratio of the total length of the boundaries to the area of ​​the image. Alternatively, the image may be divided into multiple regions, and the maximum boundary density in each region may be used.

[0027] The CPU 11 determines the beam diameter B of the laser light L1 to be incident on the diffractive optical element 34 based on the derived complexity (step S102). For example, the CPU 11 determines the beam diameter B by referring to a first beam diameter setting table (not shown). In the first beam diameter setting table, the beam diameter B is set to "small" when the complexity is less than X1, "medium" when the complexity is equal to or greater than X1 and less than X2, and "large" when the complexity is equal to or greater than X2. Specific values ​​of the complexities X1 and X2 and the values ​​of the beam diameter B for "small," "medium," and "large" are predetermined and stored in the storage unit 13. The CPU 11 identifies the level to which the complexity derived in step S102 belongs among the three levels in the first beam diameter setting table and identifies the beam diameter B associated with that level. Note that the intervals of the beam diameter B are not limited to three levels. The first beam diameter setting table is stored in the storage unit 13, for example.

[0028] The CPU 11 operates the optical system driver 32 to adjust the beam diameter B of the laser light L1 to the determined beam diameter B (step S103). Here, the CPU 11 transmits a control signal specifying the rotation direction and rotation amount of the cam barrel 41 to the optical system driver 32, thereby causing the optical system driver 32 to rotate the cam barrel 41 by the specified rotation amount in the specified rotation direction. This moves the second convex lens 332 and the concave lens 333 in the optical axis direction, thereby adjusting the beam diameter B of the laser light L1 incident on the diffractive optical element 34.

[0029] The CPU 11 sends the image data 132 used to derive the complexity in step S101 and a control signal to the display element 35, causing the display element 35 to start operating (step S104). Here, the CPU 11 controls the liquid crystal drive circuit of the display element 35 so that pixels in the image region R1 corresponding to the image related to the image data 132 are turned on and the remaining pixels in the light-shielded region R2 are turned off. Next, the CPU 11 supplies a drive current to the light source 31, causing the light source 31 to emit laser light L1. The beam diameter B of this laser light L1 is adjusted by the optical system 33, and the diffractive optical element 34 converts it into dot pattern light L2. Only the branched light incident on the image region R1 of the display element 35 is transmitted and projected as image light L3 onto the projection target 2 (step S105). As a result, the image pattern IP is projected onto the projection target 2. When step S105 is completed, the CPU 11 ends the projection process.

[0030] The execution timing of steps S104 and S105 can be changed as appropriate. For example, steps S104 and S105 may be executed before step S101 to project image light L3 with beam diameter B before adjustment, and then steps S101 to S103 may be executed to adjust beam diameter B.

[0031] As another method for adjusting the beam diameter B according to the complexity of the image, when the complexity is equal to or greater than a predetermined threshold, the beam diameter B of the laser light L1 may be adjusted so that adjacent dots D projected onto the projection target 2 partially overlap. In other words, the beam diameter B of the laser light L1 may be adjusted so that the diameter dD of the dots D is larger than the arrangement pitch pD. The arrangement pitch pD is determined by the distance d from the projection device 1 to the projection target 2, so the beam diameter B may be adjusted so that the diameter dD is larger than the arrangement pitch pD based on the distance d acquired from the distance sensor 20. Table data that associates the distance d with the beam diameter B that causes the dots D to partially overlap at the distance d may be stored in the storage unit 13, and the beam diameter B corresponding to the acquired distance d may be identified from the table data. Note that when the complexity is equal to or greater than a predetermined threshold, if the diameter dD of the dots D is smaller than the arrangement pitch pD even when the beam diameter B is adjusted to the maximum value, the beam diameter B may be adjusted to the maximum value.

[0032] Next, a second method for adjusting the beam diameter B of the laser light L1 in the projection device 1 will be described. When projecting an image pattern IP onto a distant projection target 2, if the brightness of each dot D constituting the image pattern IP is low, the image pattern IP becomes difficult to view. The brightness of the dots D decreases as the beam diameter B of the laser light L1 increases to increase the diameter dD of the dots D, and increases as the beam diameter B of the laser light L1 decreases to decrease the diameter dD of the dots D. Therefore, the beam diameter B of the laser light L1 may be adjusted so that the beam diameter B of the laser light L1 decreases as the distance d from the projection device 1 to the projection target 2 increases. This reduces the diameter dD of the dots D when the projection target 2 is far away, thereby increasing the brightness of the dots D and making the image pattern IP more visible.

[0033] The projection process executed by the CPU 11 to adjust the beam diameter B according to the distance d will be described with reference to the flowchart in Fig. 15. When the projection process is started, the CPU 11 acquires distance information relating to the distance d from the projection device 1 to the projection target 2 from the distance sensor 20 (step S201). The distance information may be the value of the distance d itself, or a value corresponding to the distance d. The value corresponding to the distance d may be, for example, the length of time from when the light-emitting unit of the distance sensor 20 emits inspection light to when the light-receiving unit receives the reflected light.

[0034] The CPU 11 determines the beam diameter B of the laser light L1 to be incident on the diffractive optical element 34 based on the acquired distance d (or a value corresponding to the distance d; the same applies below) (step S202). For example, the CPU 11 determines the beam diameter B by referring to a second beam diameter setting table (not shown). In the second beam diameter setting table, the beam diameter B is set to "large" when the distance d is less than d1, "medium" when the complexity is d1 or more and less than d2, and "small" when the complexity is d2 or more. Specific values ​​of the distances d1 and d2 and the values ​​of the beam diameter B for "small," "medium," and "large" are predetermined and stored in the storage unit 13. The CPU 11 identifies one of the three levels in the second beam diameter setting table to which the distance d derived in step S202 belongs, and identifies the beam diameter B associated with that level. Note that the intervals of the beam diameter B are not limited to three levels. The second beam diameter setting table is stored in, for example, the storage unit 13. The processing in steps S203 to S205 is the same as the processing in steps S103 to S105 in FIG. 14, and therefore a description thereof will be omitted.

[0035] As described above, the projection device 1 according to this embodiment includes a light source 31 that emits laser light L1, a diffractive optical element 34 that converts the laser light L1 incident from the light source 31 into dot pattern light L2 that can form multiple dots D, each having a diameter dD corresponding to the beam diameter B of the laser light L1, on the projection target 2, and an optical system 33 that is disposed in the optical path of the laser light L1 between the light source 31 and the diffractive optical element 34 and that can change the beam diameter B of the laser light L1 incident on the diffractive optical element 34. By changing the beam diameter B of the laser light L1, the thickness of the branched beams that constitute the dot pattern light L2 and the diameter dD of the dots D formed by the branched beams can be easily adjusted. For example, by increasing the diameter dD of the dots D, it is possible to project a highly complex image pattern IP using a method of partially blocking the light from the multiple dots D. Furthermore, by adjusting the diameter dD of the dots D, the brightness of the dots D can be easily adjusted. For example, by reducing the diameter dD of the dots D, the brightness of each dot D can be increased, making the image pattern IP more visible even when projected onto a distant projection target 2. Furthermore, regardless of the distance d from the projection device 1 to the projection target 2, the dots D are projected in focus onto the projection target 2, eliminating the need to provide a lens member or the like after the diffractive optical element 34. This allows for wide-angle, high-brightness image projection, while also enabling the projection device 1 to be made smaller, lighter, and less expensive.

[0036] The projection device 1 also includes a display element 35 onto which the dot pattern light L2 is incident, and which uses a portion of the dot pattern light L2 to generate image light L3 to be projected onto the projection target 2. This makes it possible to generate image light L3 for projecting a desired image pattern IP by a simple method of controlling the image region R1 of the display element 35. Furthermore, by changing the shape of the image region R1 in accordance with the image data 132, it is possible to change the projected image pattern IP without replacing the diffractive optical element 34.

[0037] The projection device 1 also includes an optical system driver 32 that drives the optical system 33 so as to change the beam diameter B of the laser light L1 incident on the diffractive optical element 34, and a CPU 11 that controls the optical system driver 32 to adjust the beam diameter B of the laser light L1. This allows the beam diameter B to be automatically adjusted under the control of the CPU 11, without the user having to directly operate the optical system 33.

[0038] Furthermore, the CPU 11 controls the optical system driver 32 so that the beam diameter B of the laser light L1 becomes smaller as the distance d increases, based on distance information relating to the distance d from the projection device 1 to the projection target 2. This reduces the diameter dD of the dots D when the projection target 2 is far away, increasing the brightness of the dots D and making the image pattern IP more visible.

[0039] Furthermore, the CPU 11 controls the optical system driver 32 based on the complexity of the image related to the image data 132 so that the beam diameter B of the laser light L1 increases as the complexity increases. This makes it possible to increase the proportion of dots D in the image pattern IP when the complexity of the image related to the image data 132 (the image corresponding to the projected image pattern IP) is high. As a result, it is possible to make the contour of even a highly complex image pattern IP easier to recognize.

[0040] Furthermore, when the complexity of the image related to the image data 132 is equal to or greater than a predetermined reference value, the CPU 11 may adjust the beam diameter B of the laser light L1 so that adjacent dots D among the multiple dots D projected onto the projection target 2 partially overlap each other. This also increases the proportion of the image pattern IP occupied by dots D. Therefore, even if the image pattern IP has a high degree of complexity, its outline can be easily recognized.

[0041] Furthermore, in the method for adjusting the projection device 1 according to this embodiment, the beam diameter B of the laser light L1 incident on the diffractive optical element 34 is adjusted using the optical system 33. This makes it possible to easily adjust the size and brightness of the multiple dots D to be projected.

[0042] Furthermore, the program 131 according to this embodiment causes the CPU 11 provided in the projection device 1 to function as a control unit that controls the optical system driving unit 32 to adjust the beam diameter B of the laser light L1. This makes it possible to easily adjust the size and brightness of the multiple dots D to be projected.

[0043] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the optical system driver 32 drives the optical system 33 under the control of the CPU 11 to adjust the beam diameter B of the laser light L1, but the present invention is not limited to this. For example, the beam diameter B may be changed by a user manually operating the optical system 33. As one example, the cam barrel 41 may be rotated by rotating a knob attached to the cam barrel 41 along the outer periphery of the cam barrel 41, thereby moving the positions of the second convex lens 332 and the concave lens 333 of the optical system 33.

[0044] In the above embodiment, a monochromatic image is projected using laser light emitted from one light source 31. However, this is not limiting, and a color image may be projected using multiple light sources emitting laser light of different colors. In this case, the image projection unit 30 is provided with two intersecting dichroic mirrors (a first dichroic mirror and a second dichroic mirror), a blue light source emitting laser light in a blue wavelength band, a green light source emitting laser light in a green wavelength band, and a red light source emitting laser light in a red wavelength band. The first dichroic mirror reflects laser light in the blue wavelength band and transmits laser light in other wavelength bands. The second dichroic mirror reflects laser light in the red wavelength band and transmits laser light in other wavelength bands. The blue light source is positioned at an angle such that the emitted laser light is reflected by the first dichroic mirror and enters the optical system 33. The green light source is disposed at an angle such that the emitted laser light passes through the first and second dichroic mirrors and enters the optical system 33. The red light source is disposed at an angle such that the emitted laser light is reflected by the second dichroic mirror and enters the optical system 33. In this configuration, the blue, green, and red light sources are caused to emit light at exclusive timings, and during the emission periods of each color, the display element 35 is driven with image data for each color corresponding to the color of the emitting light source, thereby making it possible to project a color image pattern IP by superimposing blue, green, and red image patterns IP on the projection target 2.

[0045] The dots D that make up the dot pattern DP do not have to be arranged in a matrix. For example, they may be arranged so that the centers of three adjacent dots D are located at the vertices of an equilateral triangle. The dot pattern DP may also be a pattern in which the dots D are arranged randomly.

[0046] Furthermore, the display element 35 is exemplified as one in which each pixel of the liquid crystal panel can be switched between two gradations, an on state and an off state, but the present invention is not limited to this, and each pixel may be switchable between three or more gradations (for example, 256 gradations). That is, the orientation state and transmittance of the liquid crystal of each pixel of the liquid crystal panel may be switchable between three or more gradations (for example, 256 gradations). In this case, it is sufficient to use, as the image data 132, data in which the pixel value of each pixel can take on the number of gradations displayed by the liquid crystal panel.

[0047] Furthermore, although a liquid crystal display element having a liquid crystal panel has been exemplified as the display element 35, the display element 35 is not limited to this. The display element 35 may also be, for example, a DMD (Digital Micromirror Device). The DMD has a plurality of micromirrors arranged in an array, and by switching the tilt angle of each micromirror in accordance with image data 132, the image light L3 is formed by the light reflected from the plurality of micromirrors.

[0048] Alternatively, the diffractive optical element 34 may directly form dot pattern light L2 capable of forming a predetermined image pattern IP. For example, by adjusting the diffraction grating pattern of the diffractive optical element 34, the dot pattern light L2 diffracted by the diffractive optical element 34 can directly form (project) an image pattern IP or the like in the shape of an arrow shown in Fig. 10. In such a case, the display element 35 may be omitted.

[0049] In the above description, an example has been disclosed in which an HDD or SSD of the storage unit 13 is used as a computer-readable medium for the program according to the present invention, but this is not limiting. Other computer-readable media may also be used, such as flash memory or CD-ROM. Furthermore, a carrier wave may also be used as a medium for providing data for the program according to the present invention via a communication line.

[0050] Furthermore, it goes without saying that the detailed configuration and detailed operation of each component of the projection device 1 in the above embodiment can be modified as appropriate without departing from the spirit of the present invention.

[0051] Although the embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0052] 1...projection device, 2...projection target, 11...CPU (control unit, control means), 31...light source, 32...optical system drive unit (drive unit), 33...optical system, 34...diffractive optical element, 35...display element, B...beam diameter, d...distance, D...dot, dD...diameter, L1...laser light, L2...dot pattern light, L3...image light, R1...image area, R2...light-shielding area

Claims

1. a light source that emits laser light; a diffractive optical element that converts the laser light incident from the light source into dot pattern light that can form a plurality of dots having a diameter corresponding to the beam diameter of the laser light on a projection target; an optical system that is arranged in an optical path of the laser light between the light source and the diffractive optical element and that is capable of changing the beam diameter of the laser light that is incident on the diffractive optical element; A projection device comprising:

2. a display element onto which the dot pattern light is incident, the display element generating image light to be projected onto the projection target using a part of the dot pattern light; The projection device according to claim 1 .

3. a driving unit that drives the optical system so that the beam diameter of the laser light incident on the diffractive optical element is changed; a control unit that controls the drive unit to adjust the beam diameter of the laser light; The projection device of claim 1 , comprising:

4. the control unit controls the drive unit based on distance information relating to a distance from the projection device to the projection target so that the beam diameter of the laser light becomes smaller as the distance increases.

4. The projection device according to claim 3.

5. a driving unit that drives the optical system so that the beam diameter of the laser light incident on the diffractive optical element is changed; a control unit that controls the drive unit to adjust the beam diameter of the laser light; Equipped with the display element generates the image light using a portion of the dot pattern light that is incident on an image area of ​​the display element based on predetermined image data, the control unit controls the drive unit based on a complexity of an image related to the image data so that the beam diameter of the laser light increases as the complexity increases.

3. The projection device according to claim 2.

6. a driving unit that drives the optical system so that the beam diameter of the laser light incident on the diffractive optical element is changed; a control unit that controls the drive unit to adjust the beam diameter of the laser light; Equipped with the display element generates the image light using a portion of the dot pattern light that is incident on an image area of ​​the display element based on predetermined image data, when the complexity of an image related to the image data is equal to or greater than a predetermined reference value, the control unit adjusts the beam diameter of the laser light so that adjacent dots among the plurality of dots projected onto the projection target partially overlap each other.

3. The projection device according to claim 2.

7. a light source that emits laser light; a diffractive optical element that converts the laser light incident from the light source into dot pattern light that can form a plurality of dots having a diameter corresponding to the beam diameter of the laser light on a projection target; an optical system that is arranged in an optical path of the laser light between the light source and the diffractive optical element and that is capable of changing the beam diameter of the laser light that is incident on the diffractive optical element; A method for adjusting a projection device comprising: adjusting the beam diameter of the laser light incident on the diffractive optical element using the optical system; How to adjust the projection device.

8. a light source that emits laser light; a diffractive optical element that converts the laser light incident from the light source into dot pattern light that can form a plurality of dots having a diameter corresponding to the beam diameter of the laser light on a projection target; an optical system that is arranged in an optical path of the laser light between the light source and the diffractive optical element and that is capable of changing the beam diameter of the laser light that is incident on the diffractive optical element; a driving unit that drives the optical system so that the beam diameter of the laser light incident on the diffractive optical element is changed; A computer provided in a projection device comprising: a control unit that controls the drive unit to adjust the beam diameter of the laser light; A program that functions as a

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