Projection device, method of adjusting the same, and program

Abstract

To provide a projection device capable of projecting an image that is easy to see, 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 to be formed on a projection target, and a drive unit for moving at least one optical element receiving the laser light such that each of the multiple dots formed on the projection target moves continuously.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, gaps occur between the multiple dots projected using a diffractive optical element, which makes it difficult to visually recognize the multiple projected dots as a single image.

[0005] An object of the present invention is to provide a projection device that can project an image that is easy to view, a method for adjusting a projection device, and a program. [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 on a projection target; a driving unit that moves at least one optical element onto which the laser light is incident so that each of the plurality of dots formed on the projection target moves continuously; Equipped with. [Effects of the Invention]

[0007] According to the present invention, it is possible to project an image that is easy to view. [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] FIG. 10 is a diagram showing a dot pattern. [Figure 5] FIG. 2 is a diagram showing an image area and a light-blocking area in a display element. [Figure 6] 6 is a diagram showing the dot pattern of FIG. 4 and an image pattern projected by the display element of FIG. 5. [Figure 7] FIG. 2 is a schematic diagram showing a mechanism for moving a diffractive optical element in a driving unit. [Figure 8] 10A and 10B are diagrams illustrating the movement of dots in response to an element moving operation targeting a diffractive optical element. [Figure 9] FIG. 10 is a diagram showing an image pattern when an element moving operation is being performed. [Figure 10] 10A and 10B are diagrams illustrating an element moving operation for a plate-like member. [Figure 11] 10A and 10B are diagrams illustrating the movement of dots in response to an element moving operation targeting a plate-like member. [Figure 12] 10A and 10B are diagrams illustrating an element moving operation for changing the tilt angle of a diffractive optical element. [Figure 13] FIG. 10 is a diagram illustrating an element moving operation for a lens. [Figure 14]10A and 10B are diagrams illustrating changes in the optical path of laser light due to element movement operations targeting a lens. [Figure 15] 10A and 10B are diagrams illustrating the movement of dots in response to an element movement operation targeting a lens. [Figure 16] 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 for projecting the image light L3. In this embodiment, the image data 132 is data in which the pixel value of each pixel is one of two 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, a lens 32 (optical element), a plate-like member 33 (optical element), a diffractive optical element (DOE) 34 (optical element), a display element 35, and a drive unit 36. The light source 31 emits linear laser light L1 in the visible wavelength range toward the diffractive optical element 34. The light source 31 includes a semiconductor light-emitting element such as a laser diode, a collimator lens that focuses the laser light output from the semiconductor light-emitting element into linear parallel light, and other elements. The positions and operations of the components of the image projection unit 30 will be described below 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 lens 32 and the plate-like member 33 are disposed in the optical path of the laser light L1 between the light source 31 and the diffractive optical element 34. The lens 32 is a collimator lens for adjusting the parallelism of the laser light L1. The plate-like member 33 is made of a material that transmits the laser light L1 and has a uniform thickness, such as a glass plate. The plate-like member 33 is disposed on the +Z direction side of the lens 32.

[0016] 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 it using the diffraction grating, 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. For example, the diffractive optical element 34 has a structure in which unit cells, the smallest unit functioning as a beam splitter, are arranged in a matrix along the XY plane. Each branched light beam generated by the diffractive optical element 34 can form a dot D (see FIG. 4) having a diameter corresponding to the beam diameter of the laser light L1 on the projection target 2. Specifically, when the dot pattern light L2 is not blocked by the display element 35, it can form a plurality of dots D corresponding to the plurality of branched light beams on the projection target 2. As shown in FIG. 4, 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. 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 the dot D refers to the diameter of a circular region having a brightness equal to or greater than 10% of the central brightness of the dot D. Meanwhile, the arrangement pitch pD of the dots D in the dot pattern DP increases as the distance d increases. In this embodiment, it is assumed that the projection target 2 is positioned such that the arrangement pitch pD in the X and Y directions is twice the diameter dD when the lens 32, the plate-like member 33, and the diffractive optical element 34 are stationary. Also, the arrangement pitch pD is 2 mm and the diameter dD is 1 mm.

[0017] The display element 35 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 applies 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, thereby controlling the alignment state of the liquid crystal layer of each pixel. 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. 5, 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. 4 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. 6. 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. 6 consisting of dots D distributed in the shape of an arrow is projected onto the projection target 2.

[0018] The driving unit 36 ​​periodically moves at least one of the lens 32, the plate-like member 33, and the diffractive optical element 34 in accordance with a control signal transmitted from the CPU 11. The mechanism of the driving unit 36 ​​and how the mechanism moves the lens 32, the plate-like member 33, and the diffractive optical element 34 will be described in detail later.

[0019] Next, the operation of the projection device 1 will be described. As described with reference to FIGS. 4 to 6, the projection device 1 projects an image pattern IP consisting of a plurality of dots D onto the projection target 2. However, since gaps occur between the plurality of dots D in the image pattern IP, it may be difficult to visually recognize the image pattern IP as a single image. For example, the greater the ratio of the arrangement pitch pD to the diameter dD, the greater the proportion of gaps in the image pattern IP, making the image more difficult to visually recognize. Furthermore, the higher the complexity of the image related to the image data 132 (for example, the higher the representative value of the spatial frequency of the image), the more difficult it becomes to recognize the contour of the image from the distribution positions of the dots D alone.

[0020] Therefore, in the projection device 1 of this embodiment, in order to improve the visibility of the image pattern IP, the drive unit 36 ​​performs an operation of periodically moving at least one of the lens 32, the plate-like member 33, and the diffractive optical element 34 (hereinafter referred to as an "element moving operation"). In response to this element moving operation, each dot D formed on the projection target 2 continuously moves within a moving region r of a predetermined size (see FIGS. 8, 11, and 15). As the dots D move at high speed within the moving region r, the viewer perceives it as if light were projected onto the entire moving region r. In other words, the apparent size of the dots D is perceived as the same as the size of the moving region r. This reduces the apparent proportion of gaps in the image pattern IP, making it easier to perceive the image pattern IP as a unified image.

[0021] The element movement operation by the driver 36 and the movement of the dots D in response to this element movement operation will be described below. First, with reference to FIG. 7, the element movement operation targeting the diffractive optical element 34 will be described. When viewed from the Z direction, the diffractive optical element 34 has a rectangular shape with four sides parallel to the Y and X directions. The diffractive optical element 34 has a frame member 34a made of a ferromagnetic material such as metal around the outer periphery of the rectangle. Transparent guide plates (not shown) are provided on the +Z and −Z sides of the diffractive optical element 34 to restrict movement of the diffractive optical element 34 in the Z direction. A plurality of (here, four) elastic members 34b (e.g., springs) are attached to the frame member 34a of the diffractive optical element 34, the other ends of which are fixed. The diffractive optical element 34 is supported by the four elastic members 34b in a state where it can move parallel to the XY plane within a certain range. The driving unit 36 ​​includes four electromagnets 361a to 361d and a driving control unit 36a that controls the operation of the electromagnets 361a to 361d. The electromagnets 361a to 361d are arranged at positions facing the +Y side, -X side, -Y side, and +X side of the diffractive optical element 34, respectively. When energized (turned ON), each of the electromagnets 361a to 361d generates a magnetic force that attracts the frame member 34a. The driving unit 36a repeatedly performs the following operations for the first to fourth periods in this order in accordance with a control signal transmitted from the CPU 11. In a first period, the driving unit 36a turns the electromagnets 361a and 361b on (powered) and the electromagnets 361c and 361d off (not powered), thereby attracting the diffractive optical element 34 to the upper right (-X and +Y directions) when viewed from the -Z direction. In a second period, the driving unit 36a turns the electromagnets 361b and 361c on and the electromagnets 361d and 361a off, thereby attracting the diffractive optical element 34 to the lower right (-X and -Y directions). In a third period, the driving unit 36a turns the electromagnets 361c and 361d on and the electromagnets 361a and 361b off, thereby attracting the diffractive optical element 34 to the lower left (+X and -Y directions).During the fourth period, the driving unit 36a turns on the electromagnets 361d and 361a and turns off the electromagnets 361b and 361c, thereby attracting the diffractive optical element 34 to the upper left (+X direction and +Y direction). After each cycle of the first to fourth periods, the diffractive optical element 34 moves to one of four positions: upper right, lower right, lower left, and upper left. In response to this movement, the center C1 of the diffractive optical element 34 makes one revolution around a rectangular (here, square) orbit T1 in a plane perpendicular to the optical axis of the laser light L1 (in the XY plane). The length of one side of the orbit T1 is defined as length M1. Length M1 corresponds to the amount of positional fluctuation of the diffractive optical element 34 due to the element fluctuation operation in the arrangement direction of the dots D (X direction or Y direction). The driving unit 36a repeatedly performs the operations of the first to fourth periods to move the diffractive optical element 34 so that the center C1 orbits T1 in the XY plane. The repetition frequency of periods P1 to P4 is, for example, 30 Hz or higher. The distance between electromagnet 361a and electromagnet 361c and / or the distance between electromagnet 361b and electromagnet 361d may be changeable. Furthermore, the drive unit 36 ​​may be able to change the distance under control of the CPU 11. Changing the distance can change the length M1 of one side of the orbit T1, i.e., the amount of positional fluctuation of the diffractive optical element 34. For example, the electromagnet 361a may be attached to the nut of a first ball screw extending in the Y direction, and the electromagnet 361b may be attached to the nut of a second ball screw extending in the X direction. In this configuration, the motor of the drive unit 36 ​​may rotate the screw shaft of the first ball screw under control of the CPU 11, thereby moving the electromagnet 361a in the Y direction, and the motor of the drive unit 36 ​​may rotate the screw shaft of the second ball screw under control of the CPU 11, thereby moving the electromagnet 361b in the X direction.

[0022] When the diffractive optical element 34 moves within the XY plane, each dot D on the projection target 2 moves in the same direction as the movement direction of the diffractive optical element 34. While the diffractive optical element 34 moves through one cycle of periods P1 to P4, the dot D on the projection target 2 moves so that the center c1 of the dot D makes one revolution around a rectangular (here, a square) orbit t1, as shown in FIG. 8. The area swept by the dot D while the center c1 of the dot D makes one revolution around the orbit t1 corresponds to the movement area r of the dot D. In this case, the movement area r is a rectangle with rounded corners. The length m1 of one side of the orbit t1 (i.e., the maximum width of the orbit t1 in the arrangement direction of the dots D) is equal to or greater than the value obtained by subtracting the diameter dD from the arrangement pitch pD of the dots D (hereinafter referred to as "pD - dD"). In other words, the length M1 of one side of the orbit T1 shown in FIG. 7 is determined so that the length m1 is equal to or greater than (pD - dD). For example, if the diameter dD is 1 mm, the arrangement pitch pD is 2 mm, and the length m1 of one side of the orbit t1 is 1 mm, the length M1 of one side of the orbit T1 of the center C1 of the diffractive optical element 34 will be approximately 30 μm to 100 μm, depending on factors such as the distance d from the projection device 1 to the projection target 2. If the length m1 is (pD - dD) or greater, the maximum width W of the movement region r in the arrangement direction of the dots D will be equal to or greater than the arrangement pitch pD, and therefore the movement regions r of dots D adjacent in the X or Y direction will come into contact with or partially overlap each other.

[0023] By repeating the operations during periods P1 to P4, the dots D continuously move circularly within the movement region r. The circular frequency of the dots D is the same as the repetition frequency of periods P1 to P4, and is therefore 30 Hz or higher. As the dots D move circularly within the movement region r at such a high frequency, the viewer perceives it as if light of approximately uniform brightness is being projected over the entire movement region r. In other words, the viewer perceives it as if light is being projected over a wider area than the range of the dots D when the diffractive optical element 34 is not moved (the circular position indicated by symbol p in FIG. 8).

[0024] When the driver 36 performs an element movement operation targeting the diffractive optical element 34 to form an arrow image region R1 on the display element 35 as shown in FIG. 5, the image pattern IP projected onto the projection target 2 will be as shown in FIG. 9. Because the maximum width W of the movement region r is equal to or greater than the arrangement pitch pD, the movement regions r corresponding to the dots D are adjacent to each other in FIG. 9, and the observer perceives the image pattern IP as if light were projected onto most of the image pattern IP. Furthermore, because light outside the contour of the image pattern IP, i.e., light incident outside the image region R1 of the display element 35, is masked by the display element 35, the contour of the image pattern IP does not blur even when each dot D moves within the movement region r due to the element movement operation. This makes it easier to perceive the image pattern IP as a single, arrow-shaped image, and to recognize the contour of the arrow. The movement regions r corresponding to adjacent dots D do not necessarily need to be adjacent to each other. That is, the length m1 of one side of the orbit t1 may be less than (pD - dD). In other words, the maximum width W of the movement region r in the arrangement direction of the dots D may be less than the arrangement pitch pD. However, in order to improve the visibility of the image pattern IP, it is preferable that the length m1 of one side of the circular orbit t1 in the arrangement direction of the dots D be equal to or greater than the radius of the dots D. In other words, it is preferable that the maximum width W of the movement region r in the arrangement direction of the dots D be equal to or greater than 1.5 times the diameter dD of the dots D. This is because, when this condition is satisfied, the visual effect of the dots D appearing to expand can be sufficiently obtained. Conversely, the maximum width W of the movement region r may be large enough to eliminate any gaps between the movement regions r in the image pattern IP.

[0025] Instead of moving the diffractive optical element 34 through four positions, the diffractive optical element 34 may be continuously moved back and forth in one direction perpendicular to the optical axis (Z axis) of the laser beam L1. For example, in FIG. 7, while the position of the diffractive optical element 34 is restricted so as not to move in the X direction, the electromagnets 361a and 361c may be alternately turned on to move the diffractive optical element 34 back and forth in the Y direction. Alternatively, while the position of the diffractive optical element 34 is restricted so as not to move in the Y direction, the electromagnets 361b and 361d may be alternately turned on to move the diffractive optical element 34 back and forth in the X direction. Alternatively, instead of using electromagnets, the diffractive optical element 34 may be moved by a piezoelectric element that deforms in response to the application of a voltage. In these cases, the apparent dots D become larger in the X or Y direction. Therefore, even with the method of moving the diffractive optical element 34 back and forth, the proportion of gaps in the image pattern IP can be reduced, making the image pattern IP easier to view as a unified image. Even when the diffractive optical element 34 is moved back and forth, it is preferable to move the diffractive optical element 34 so that the maximum width W of the movement area r in the arrangement direction of the dots D is 1.5 times or more the diameter dD of the dots D or the arrangement pitch pD or more.

[0026] Next, with reference to FIG. 10 , an element moving operation targeting the plate-shaped member 33 will be described. In the element moving operation targeting the plate-shaped member 33, the driving unit 36 ​​periodically changes the tilt angle θ of the plate-shaped member 33 from a plane (XY plane) perpendicular to the optical axis of the laser light L1. To change the tilt angle θ, the driving unit 36 ​​has, for example, the following mechanism. The plate-shaped member 33 is attached to a support unit (not shown) so as to be rotatable about a rotation axis 331 parallel to the X axis. Ferromagnetic bodies 332 are attached to the ends of the plate-shaped member 33 in the +Y direction and the −Y direction, respectively. The driving unit 36 ​​includes two electromagnets 362 arranged near the two ferromagnetic bodies 332 and a driving control unit 36b that controls the operation of the electromagnets 362. The driving control unit 36b alternately switches the two electromagnets 362 on and off, thereby attracting and repelling the ferromagnetic bodies 332 at the ends of the plate-shaped member 33 to and from the electromagnets 362. This allows the tilt angle θ of the plate-shaped member 33 to be periodically changed at the on / off switching frequency of the electromagnet 362. The maximum value of the tilt angle θ corresponds to the amount of angle fluctuation of the plate-shaped member 33 due to the element moving operation. The frequency of the fluctuation of the tilt angle θ can be, for example, 30 Hz or higher. Note that the range of fluctuation of the tilt angle θ may be adjusted by changing the position of the electromagnet 362. Furthermore, the drive unit 36 ​​may be able to change the position of the electromagnet 362 under control of the CPU 11. For example, the electromagnets 362 may be attached to two support shafts that are independently rotatable about the rotation shaft 331 when viewed from the X direction, and the motor of the drive unit 36 ​​may rotate each support shaft by a specified angle under control of the CPU 11, thereby changing the position of the electromagnet 362 along an imaginary circle centered on the rotation shaft 331.

[0027] As shown in FIG. 10, if the thickness of the plate-like member 33 is th, the refractive index is n, and the deviation amount of the optical axis of the laser light L1 in the Y direction before and after passing through the plate-like member 33 is Δy, Δy when the plate-like member 33 is tilted by the tilt angle θ is expressed by the following equation. Δy=th·sinθ[1-{(1-sin 2 θ) / (n 2 -sin 2 θ)} 1 / 2 ] For example, when n = 1.5165, t = 1.1 mm, and θ = 0.5 deg, Δy is approximately 3 μm. In this way, by periodically changing the tilt angle θ of the plate-like member 33, the optical axis of the laser light L1 can be periodically shifted in the Y direction. In response to this periodic shift of the optical axis of the laser light L1, the dot D formed on the projection target 2 continuously moves back and forth within an oval-shaped moving region r extending in the Y direction, as shown in FIG. 11. Furthermore, the center c2 of the dot D moves back and forth along a path t2 extending in the Y direction. As a result, the apparent size of the dot D increases in the Y direction. In this case, the length m2 of the path t2 in the Y direction is preferably (pD - dD) or greater, similar to the length m1 in FIG. 8. In other words, the maximum width W of the moving region r in the Y direction is preferably greater than or equal to the arrangement pitch pD of the dots D. However, the length m2 is preferably greater than or equal to the radius of the dot D, and the maximum width W of the moving region r is preferably greater than or equal to 1.5 times the diameter dD of the dot D. In this way, by changing the tilt angle θ of the plate-like member 33, the ratio of gaps in the image pattern IP can be reduced, making it easier to visually recognize the image pattern IP as a single image. Note that the rotation axis of the plate-like member 33 is not limited to the X-axis, and any axis parallel to the XY plane may be used as the rotation axis.

[0028] 12, the tilt angle of the diffractive optical element 34 from the XY plane may be changed periodically. For example, by rotating the diffractive optical element 34 around the X axis to periodically change the tilt angle, the traveling direction of the dot pattern light L2 and the image light L3 can be periodically varied in the Y direction. As a result, the dots D formed on the projection target 2 continuously move back and forth within a movement region r extending in the Y direction, and the apparent size of the dots D increases in the Y direction.

[0029] Next, with reference to FIG. 13, an element moving operation targeting the lens 32 will be described. As shown in FIG. 13, the lens 32 is circular when viewed in the Z direction, and a gear 321 is provided on its outer periphery. Meanwhile, the driving unit 36 ​​has an internal gear 363 with a diameter larger than that of the lens 32, and the gear 321 meshes with the internal gear 363. The driving unit 36 ​​also includes a motor that rotates the lens 32, and rotates the lens 32 at a rotation speed in accordance with a control signal transmitted from the CPU 11. For example, as shown in FIG. 14, the driving unit 36 ​​includes a crank 365 having an axis a1 at one end attached to the motor 364 and an axis a2 at the other end attached to the center of the lens 32, and the motor 364 that rotates the crank 365. The axis a1 of the crank 365 is collinear with the optical axis of the laser beam L1 and is on a line passing through the center of the internal gear 363. The axis a2 of the crank 365 is on a line passing through the center of the lens 32 and parallel to the optical axis of the laser beam L1. The lens 32 has a center position regulated by the axis a2, but is rotatable about the axis a2. The crank 365 is shaped so that it does not interfere with the laser light L1 or with the components of the image projection unit 30, including the light source 31, during rotation. In this configuration, the motor 364 rotates the crank 365, causing the lens 32 to rotate along the inner circumference of the internal gear 363. As the gear 321 rotates while meshing with the internal gear 363, the lens 32 rotates on its own axis and moves along the inner circumference of the internal gear 363. In response to this movement of the lens 32, the center C3 of the lens 32 moves along a circular orbit T3 having a diameter M3. That is, the drive unit 36 ​​moves the lens 32 so that the center C3 of the lens 32 moves circularly (around the circular orbit T3) within a plane (XY plane) perpendicular to the optical axis of the laser light L1. The diameter M3 corresponds to the amount of positional movement of the lens 32 due to the element movement in the arrangement direction of the dots D.

[0030] As the lens 32 moves along the inner circumference of the internal gear 363, the position of the lens 32 changes periodically in the X and Y directions, as shown in FIG. 14. As the incident position of the laser light L1 shifts from the center of the lens 32, the laser light L1 incident on the lens 32 is refracted. As the center C3 of the lens 32 moves so as to revolve around a circular orbit T3, the refraction direction of the laser light L1 by the lens 32 changes so as to draw a circle when viewed from the Z direction. As a result, as shown in FIG. 15, the dot D on the projection target 2 moves so that the center c3 of the dot D revolves around a circular orbit t3. Therefore, the dot D moves so as to rotate within the circular movement region r. This increases the apparent diameter of the dot D. In this case, the diameter m3 of the orbit t3 is preferably equal to or greater than (pD - dD), similar to the length m1 in FIG. 8. In other words, the maximum width W (diameter) of the movement region r is preferably equal to or greater than the arrangement pitch pD of the dots D. However, it is preferable that the length m3 is equal to or greater than the radius of the dot D, and the maximum width W of the movement region r is equal to or greater than 1.5 times the diameter dD of the dot D. In this way, by moving the lens 32 so that the center C3 describes a circular orbit T2, the ratio of gaps in the image pattern IP can be reduced, making it easier to view the image pattern IP as a unified image. Note that multiple internal gears 363 with different diameters may be provided, and the amount of positional fluctuation of the lens 32 (the diameter M3 of the orbit T3) may be changed by changing the internal gear 363 that meshes with the gear 321 of the lens 32. Furthermore, the drive unit 36 ​​may be able to change the internal gear 363 that meshes with the gear 321 of the lens 32 under control of the CPU 11.

[0031] Alternatively, a gear may be provided on the outer periphery of the circular diffractive optical element 34, and the diffractive optical element 34 may be rotated along the inner periphery of the internal gear. In this case, the dot pattern light L2 and the dot pattern DP rotate, but the dot pattern light L2 is masked by the display element 35 in the shape of a predetermined image region R1, so that an image pattern IP of a desired shape can be projected onto the projection target 2. Furthermore, the rotation of the dot pattern light L2 and the dot pattern DP can increase the movement region r corresponding to each dot D, thereby effectively reducing the apparent gaps between the dots D. Note that the circular motion of the lens 32 and / or the diffractive optical element 34 is not limited to rotation, and may be translational circular motion in which the lens 32 and / or the diffractive optical element 34 moves in a circular motion without rotation.

[0032] Furthermore, the element movement operation for the lens 32 may be an operation of moving the lens through four positions as shown in FIG. 7, an operation of moving the lens back and forth within the XY plane, or an operation of periodically changing the tilt angle from the XY plane as shown in FIG. 10.

[0033] The above describes the element movement operations for the lens 32, the plate-like member 33, and the diffractive optical element 34. However, the element movement operations may be performed for two or more of the lens 32, the plate-like member 33, and the diffractive optical element 34. In this case, the two or more target optical elements may be periodically moved in different manners. For example, the first optical element may be moved by a first positional variation amount (or a first angular variation amount), and the second optical element may be moved by a second positional variation amount (or a second angular variation amount) smaller than the first positional variation amount. In this manner, the element movement operation of the first optical element can reduce the apparent gaps between the dots D, and the element movement operation of the second optical element can reduce speckle noise in the image pattern IP. Here, speckle noise is noise caused by random interference fringes resulting from scattering of the image light L3, which is coherent light, on the surface of the projection target 2. In this case, the first positional fluctuation amount or the first angular fluctuation amount may be set to a movement amount such that the maximum width W (first maximum width) of the movement region r of the dots D is at least 1.5 times the diameter dD of the dots D or at least the arrangement pitch pD, and the first positional fluctuation amount or the first angular fluctuation amount may be set to a movement amount such that the maximum width W of the movement region r is at most 1 / 5, more preferably at most 1 / 10, of the first maximum width. For example, the first positional fluctuation amount may be set to several tens of μm, and the second positional fluctuation amount may be set to approximately 2 to 3 μm. Furthermore, the frequency of the positional fluctuation or angular fluctuation of the second optical element (e.g., 120 Hz or higher) may be higher than the frequency of the positional fluctuation or angular fluctuation of the first optical element (e.g., 30 Hz or higher).

[0034] Next, a method for adjusting the element movement operation according to the distance d between the projection device 1 and the projection target 2 will be described. As described above, the arrangement pitch pD of the dots D formed on the projection target 2 increases as the distance d increases, leading to a decrease in the visibility of the image pattern IP. For this reason, the element movement operation by the drive unit 36 ​​may be adjusted so that the maximum width W of the movement area r increases as the distance d increases. The projection process executed by the CPU 11 to adjust the element movement operation by the drive unit 36 ​​according to the distance d will be described with reference to the flowchart in FIG. 16. This projection process is started when the user of the projection device 1 performs an operation to instruct projection of an image.

[0035] 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 S101). 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.

[0036] Based on the acquired distance d (or a value corresponding to the distance d; the same applies below), the CPU 11 determines the amount of positional variation and / or the amount of angular variation of the optical element to be subjected to the element movement operation, among the lens 32, the plate-like member 33, and the diffractive optical element 34 (step S102). The amount of positional variation and / or the amount of angular variation corresponding to the distance d may be associated in advance and stored in the storage unit 13 as table data. Furthermore, the arrangement pitch pD of the dots D according to the distance d may be specified by table data or the like, and the amount of positional variation or the amount of angular variation may be determined so that the maximum width W of the movement region r has a size corresponding to the arrangement pitch pD (for example, equal to or greater than the arrangement pitch pD).

[0037] The CPU 11 operates the driver 36 to start an element moving operation that changes the position and / or angle of the optical element that is the target of the element moving operation (step S103). For example, in the example shown in Fig. 7, the CPU 11 adjusts the distance between the electromagnets 361a and 361c and / or the distance between the electromagnets 361b and 361d using a motor and a ball screw (not shown) of the driver 36, and then operates the electromagnets 361a to 361d according to the above-mentioned pattern, thereby repeatedly moving the diffractive optical element 34 through four positions. In the example shown in Fig. 10, the CPU 11 adjusts the position of the electromagnet 362 using a motor and a support shaft (not shown) of the driver 36, and then alternately operates the electromagnet 362, thereby periodically changing the tilt angle θ of the plate-like member 33. In addition, in the example shown in Figure 13, the CPU 11 moves the internal gear 363 or the lens 32 so that the internal gear 363 corresponding to the determined position fluctuation amount engages with the gear 321 of the lens 32, and rotates the lens 32 along the inner circumference of the internal gear 363.

[0038] The CPU 11 sends image data 132 and a control signal to the display element 35 to start the operation of the display element 35 (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 pixels in the remaining light-shielding region R2 are turned off. Next, the CPU 11 supplies a drive current to the light source 31 to cause the light source 31 to emit laser light L1. This laser light L1 is converted into dot pattern light L2 by the diffractive optical element 34, and 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. Furthermore, because one of the optical elements is continuously moving, the dots D continuously move within the movement region r, increasing their apparent size. After step S105 is completed, the CPU 11 ends the projection process.

[0039] 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 the image light L3, and then steps S101 to S103 may be executed to move the optical element and the dots D.

[0040] 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 capable of forming multiple dots D on the projection target 2, and a drive unit 36 ​​that moves at least one of the lens 32 onto which the laser light L1 is incident, the plate-like member 33, and the diffractive optical element 34 (at least one optical element) so that each of the multiple dots D formed on the projection target 2 moves continuously. This allows the dots D to appear to be enlarged. Therefore, the apparent proportion of gaps between the dots D in the image pattern IP projected onto the projection target 2 can be reduced, making the image pattern IP more easily visible as a unified image. Furthermore, the contours of the image pattern IP can be more easily recognized. As a result, an image that is easy to view can be projected. Furthermore, because the dots D are projected onto the projection target 2 in a focused state regardless of the distance d from the projection device 1 to the projection target 2, there is no need to provide a lens element or the like downstream of the diffractive optical element 34. This allows for wide-angle and high-brightness image projection, and also allows for the projection device 1 to be made smaller, lighter, and less expensive.

[0041] Furthermore, the driving unit 36 ​​periodically moves at least one of the lens 32, the plate-like member 33, and the diffractive optical element 34 so that each of the multiple dots D formed on the projection target 2 continuously moves within a movement area r of a predetermined size. This allows the dots D to be visually recognized as having the size of the movement area r.

[0042] Furthermore, the maximum width W of the movement region r in the arrangement direction of the multiple dots D on the projection target 2 is 1.5 times or more the diameter dD of the dots D formed on the projection target 2. This allows the apparent size of the dots D to be enlarged by 1.5 times or more, effectively reducing the proportion of the image pattern IP occupied by gaps between the dots D.

[0043] Furthermore, the maximum width W of the movement region r in the arrangement direction of the multiple dots D on the projection target 2 is equal to or greater than the arrangement pitch pD in the arrangement direction of the dots D formed on the projection target 2. This allows the movement regions r of adjacent dots D in the arrangement direction to be in contact with or partially overlap each other. This makes it possible to more effectively reduce the apparent proportion of the image pattern IP occupied by the gaps between the dots D.

[0044] Furthermore, the driver 36 moves the lens 32 and / or the diffractive optical element 34 so that the center C1 or C2 moves along the orbit T1 or T2 in a plane perpendicular to the optical axis of the laser light L1. This creates the visual effect of the dots D expanding two-dimensionally. This effectively reduces the apparent proportion of the image pattern IP occupied by the gaps between the dots D.

[0045] Furthermore, by moving the lens 32 so that the center moves in a circular motion, the visual effect of expanding the diameter of the dots D can be obtained. This also makes it possible to more effectively reduce the apparent proportion of the image pattern IP occupied by the gaps between the dots D.

[0046] Furthermore, the drive unit 36 ​​may reciprocate the lens 32 and / or the diffractive optical element 34 in a direction perpendicular to the optical axis of the laser light L1, which also produces the visual effect of the dots D expanding.

[0047] Furthermore, the driving unit 36 ​​periodically changes the tilt angle θ of the plate-like member 33 from a plane perpendicular to the optical axis of the laser light L1, thereby allowing the dot D to move continuously within a movement area r extending in a certain direction, thereby producing the visual effect of the dot D expanding.

[0048] The driving unit 36 ​​may also periodically change the tilt angle of the diffractive optical element 34 from a plane perpendicular to the optical axis of the laser light L1, thereby allowing the dot D to move continuously within a movement region r extending in a certain direction, thereby producing the visual effect of the dot D expanding.

[0049] Furthermore, the driver 36 may periodically move at least two optical elements in different modes. For example, by moving the first optical element by a first positional variation amount (or a first angular variation amount) and moving the second optical element by a second positional variation amount smaller than the first positional variation amount (or a second angular variation amount smaller than the first angular variation amount), the element movement operation of the first optical element can reduce the apparent gaps between the dots D, and the element movement operation of the second optical element can reduce speckle noise in the image pattern IP.

[0050] The projection device 1 also includes a CPU 11 that controls the operation of the drive unit 36, and the CPU 11 controls the drive unit 36 ​​based on distance information relating to the distance d from the projection device 1 to the projection target 2 so that the maximum width W of the movement area r in the arrangement direction of the multiple dots D on the projection target 2 increases as the distance d increases. As the distance d increases, the arrangement pitch pD of the dots D increases, and the gaps between the dots D become larger. However, with the above control, the larger the gaps between the dots D, the larger the movement area r of the dots D, making it possible to enlarge the apparent dots D. Therefore, the apparent proportion of the image pattern IP occupied by the gaps between the dots D can be appropriately reduced according to the arrangement pitch pD.

[0051] 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 allows the outline of the image pattern IP to be defined by the display element 35, so that even if each dot D moves within the movement region r due to an element movement operation, the outline of the image pattern IP does not blur.

[0052] Furthermore, the control method for the projection device 1 according to this embodiment causes the drive unit 36 ​​to perform an element movement operation so that each of the multiple dots D formed on the projection target 2 moves continuously. Furthermore, the program 131 according to this embodiment causes the CPU 11 to function as a control means, and the control means causes the drive unit 36 ​​to operate so that each of the multiple dots D formed on the projection target 2 moves continuously. This makes it possible to make the image pattern IP more easily visible as a single image. Therefore, it is possible to project an image that is easy to view.

[0053] The present invention is not limited to the above-described embodiment and various modifications are possible. For example, in the above-described embodiment, a monochromatic image is projected using laser light emitted from one light source 31. However, this is not limiting. 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 diffractive optical element 34. 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 diffractive optical element 34. 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 diffractive optical element 34. 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.

[0054] In addition, one or both of the lens 32 and the plate-like member 33 may be omitted. In addition, the image projection unit 30 may have optical elements other than the lens 32, the plate-like member 33, and the diffractive optical element .

[0055] 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.

[0056] 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.

[0057] Furthermore, although a liquid crystal display element is exemplified as the display element 35, the display element 35 is not limited to this. The display element 35 may 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.

[0058] 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 FIGS. 6 and 9. In such a case, the display element 35 may be omitted.

[0059] Furthermore, the driving unit 36 ​​may move at least one of the lens 32, the plate-like member 33, and the diffractive optical element 34 non-periodically (for example, randomly).

[0060] 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.

[0061] 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.

[0062] 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]

[0063] 1...projection device, 2...projection target, 11...CPU (control unit, control means), 31...light source, 32...lens (optical element), 33...plate-shaped member (optical element), 34...diffractive optical element (optical element), 35...display element, 36...drive unit, D...dot, L1...laser light, L2...dot pattern light, L3...image light, dD...diameter, pD...arrangement pitch, r...movement area, T1, T2...orbit, W...maximum width, θ...tilt angle

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 on a projection target; a driving unit that moves at least one optical element onto which the laser light is incident so that each of the plurality of dots formed on the projection target moves continuously; A projection device comprising:

2. the driving unit periodically moves the at least one optical element so that each of the plurality of dots formed on the projection target continuously moves within a movement area of ​​a predetermined size. The projection device according to claim 1 .

3. a maximum width of the movement area in the arrangement direction of the plurality of dots on the projection target is 1.5 times or more the diameter of the dots formed on the projection target; 3. The projection device according to claim 2.

4. a maximum width of the movement area in an arrangement direction of the plurality of dots on the projection target is equal to or greater than an arrangement pitch of the dots formed on the projection target in the arrangement direction; 3. The projection device according to claim 2.

5. the at least one optical element includes at least one of a lens or the diffractive optical element; the driving unit moves the at least one optical element so that a center of the optical element makes a circular motion within a plane perpendicular to the optical axis of the laser light. The projection device according to claim 1 .

6. the at least one optical element includes at least one of a lens or the diffractive optical element; the driving unit reciprocates the at least one optical element in a direction perpendicular to the optical axis of the laser light. The projection device according to claim 1 .

7. the at least one optical element includes the diffractive optical element; the driving unit periodically changes the tilt angle of the diffractive optical element from a plane perpendicular to the optical axis of the laser light. The projection device according to claim 1 .

8. The driving unit periodically moves at least two of the optical elements in different modes. The projection device according to claim 1 .

9. a control unit that controls the drive unit based on distance information relating to a distance from the projection device to the projection target so that the greater the distance, the greater the maximum width of the movement area in the arrangement direction of the plurality of dots on the projection target, 3. The projection device according to claim 2.

10. 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 any one of claims 1 to 9.

11. 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 on a projection target; a driving unit that moves at least one optical element onto which the laser light is incident; A method for controlling a projection device comprising: causing the driving unit to perform the operation so that each of the dots formed on the projection target among the plurality of dots continuously moves; A method for controlling a projection device.

12. 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 on a projection target; a driving unit that moves at least one optical element onto which the laser light is incident; A computer provided in a projection device comprising: a control means for causing the driving unit to perform the operation so that each of the plurality of dots formed on the projection target moves continuously; A program that functions as a

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