Projection apparatus

Abstract

To change an image to be projected without exchanging a diffraction optical element.SOLUTION: The projection apparatus includes a light source configured to emit coherent light, a diffraction optical element configured to convert the coherent light emitted from the light source into pattern light having a predetermined directivity and forming a predetermined pattern on a projection target, and a pixel including a transmitting portion configured to transmit light and a non-transmitting portion configured not to transmit light, the display device includes a display element on which pattern light is incident, a first lens disposed on a diffractive optical element side of the display element and corresponding to a pixel, and a second lens disposed on an opposite side of the diffractive optical element side of the display element and corresponding to the pixel, wherein the first lens condenses incident pattern light on a transmission portion of the corresponding pixel, and the second lens refracts light condensed by the first lens and transmitted through the transmission portion of the corresponding pixel so as to return the light to directional light.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a projection apparatus. [Background technology]

[0002] Conventionally, there is a projection device that diffracts laser light using a diffractive optical element to project an image of a predetermined pattern onto a projection target such as a screen. For example, Patent Document 1 discloses a projection device that can project an image of a linear pattern using a diffractive optical element. [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 techniques have a problem in that the diffractive optical element needs to be replaced in order to change the projected image.

[0005] The present invention aims to change the projected image without replacing the diffractive optical element. [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 coherent light; a diffractive optical element that converts the coherent light emitted from the light source into pattern light that has a predetermined directivity and forms a predetermined pattern on a projection target; a display element having pixels each composed of a transmissive portion that transmits light and a non-transmissive portion that does not transmit light, and on which the pattern light is incident; a first lens that is disposed on the diffractive optical element side of the display element and corresponds to the pixel; a second lens disposed on the opposite side of the display element from the diffractive optical element side and corresponding to the pixel; Equipped with the first lens focuses the incident pattern light onto the transmission portion of the corresponding pixel; The second lens refracts the light that has been collected by the first lens and transmitted through the transmission portion of the corresponding pixel so as to return it to the directional light. [Effects of the Invention]

[0007] According to the present invention, the projected image can be changed without replacing the diffractive optical element. [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. 2 is a schematic cross-sectional view showing the configuration of a display panel, illustrating a schematic cross-section passing through the optical axis of a laser beam and perpendicular to the X direction. [Figure 5] FIG. 2 is a diagram showing the configuration of a pixel of a display element. [Figure 6] FIG. 10 is a diagram showing a dot pattern. [Figure 7] FIG. 2 is a diagram showing an image area and a light-blocking area in a display element. [Figure 8] 8A and 8B are diagrams showing the dot pattern of FIG. 6 and the image pattern projected by the display element of FIG. 7; [Figure 9] 3A and 3B are diagrams illustrating the light-collecting and refracting actions of a first lens and a second lens on the optical axis. [Figure 10] 10A and 10B are diagrams showing the positions of a first lens and a second lens at positions away from the optical axis, and the light-collecting and refracting effects thereof. [Figure 11] FIG. 10 is a schematic cross-sectional view showing another configuration of the display panel, illustrating a schematic cross-section passing through the optical axis of the laser light and perpendicular to the X direction. [Figure 12] 10A and 10B are diagrams showing the positions and orientations of a first lens and a second lens located away from the optical axis, and the light-collecting and refracting effects thereof. 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 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), a RAM 12 (Random Access Memory), a storage unit 13, and an image projection unit 20. 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, a communication unit that communicates with external devices, and a distance sensor that detects the distance to the projection target 2.

[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 (e.g., 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 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 FIGS. 2 and 3, the image projection unit 20 includes a light source 21, a diffractive optical element (DOE) 22, and a display panel 23. The light source 21 emits linear laser light L1 in the visible wavelength range toward the diffractive optical element 22. The laser light L1 is a form of coherent light. The light source 21 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 20 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.

[0014] The diffractive optical element 22 is a light-transmitting plate-like member on which a diffraction grating having a fine uneven structure is formed. The diffractive optical element 22 is arranged so that the surface of the diffraction grating is perpendicular to the optical axis of the laser light L1. The diffractive optical element 22 transmits the laser light L1 incident from the light source 21 and diffracts the laser light L1 using the diffraction grating, thereby converting the laser light L1 into dot pattern light L2 (pattern light) 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 22 has an uneven structure adjusted so that the diffracted beams of the laser light L1 constructively interact with each other at the positions of the branched beams. Hereinafter, the optical axis of the laser light L1 will be referred to as "optical axis A" (see FIG. 4) and the optical axis of each branched beam of the dot pattern light L2 will be referred to as "optical axis B" (see FIG. 4). In this way, the diffractive optical element 22 functions as a transmissive beam splitter that branches the laser light L1 into multiple branched beams. Each branched light beam can form a dot D (see FIG. 6 ) 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 24, it can form a plurality of dots D corresponding to the plurality of branched light 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. 6 . The diameter of each dot D formed by the dot pattern light L2 is approximately constant regardless of the distance from the projection device 1 to the projection target 2. In other words, each branched light beam of the dot pattern light L2 is a parallel light beam having a directivity such that the beam diameter is approximately constant at each position on the optical path. The diameter of a 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 of the dots D in the dot pattern DP increases as the distance from the projection device 1 to the projection target 2 increases. If the distance from the projection device 1 to the projection target 2 is approximately 2 m and the angle θ between the optical axis A of the laser light L1 and the optical axis B of the dot pattern light L2 is a maximum of 45°, the width of the dot pattern DP on the projection target 2 will be approximately 4 m.

[0015] As shown in FIG. 4, the display panel 23 includes a pair of transparent substrates 231 and 232, a display element 24 provided between the substrates 231 and 232, a plurality of first lenses 25 provided inside the substrate 231, and a plurality of second lenses 26 provided inside the substrate 232. The display panel 23 is a dot-matrix transmissive liquid crystal panel arranged perpendicular to the optical axis A of the laser light L1 on the +Z direction side of the diffractive optical element 22. The above-mentioned dot pattern light L2 is incident on the display panel 23. Polarizing plates (not shown) are arranged on both sides of the display panel 23. In this embodiment, the distance in the Z direction between the diffractive optical element 22 and the display panel 23 is approximately 30 mm.

[0016] The display element 24 is a portion of the display panel 23 sandwiched between the substrates 231 and 232. The display element 24 is a liquid crystal display element and includes a liquid crystal layer sealed between the substrates 231 and 232, multiple pixel electrodes formed on the opposing surface of the substrate 231 or 232, a counter electrode opposing the multiple pixel electrodes, multiple scanning lines, multiple data lines, and a switching element provided for each pixel electrode. As shown in FIG. 5 , the display element 24 includes multiple pixels 241 arranged in a matrix. The pixels 241 are square when viewed in the Z direction. Each pixel 241 includes a pixel electrode for applying a drive voltage between the liquid crystal layer in the pixel 241 and the counter electrode, and a switching element for selectively applying the drive voltage to the pixel electrode. Each pixel 241 includes a transmissive portion 241a that transmits the incident dot pattern light L2 and a non-transmissive portion 241b that does not transmit the dot pattern light L2. The non-transmissive portion 241b is provided with the above-mentioned switching elements, scanning lines, data lines, etc. A signal for selecting a pixel row is supplied to the scanning line. A drive voltage according to an image is supplied to each pixel 241 in the selected pixel row to the data line. In this embodiment, the size of the arrangement area of ​​the multiple pixels 241 is 3 inches, the aspect ratio is 3:4, and the resolution is VGA (480 × 640 pixels). The arrangement pitch of the pixels 241 is 0.095 mm in both the horizontal direction (X direction) and the vertical direction (Y direction), and the width of the non-transmissive portion 241b is 0.035 mm. The aperture ratio, i.e., the ratio of the area of ​​the transmissive portion 241a to the area of ​​the pixel 241, is 40%.

[0017] A liquid crystal drive circuit (not shown) for driving the display element 24 is provided inside or outside the display panel 23. The liquid crystal drive circuit applies a drive voltage (corresponding to the pixel value of the pixel in the image data 132) to each pixel 241 according to the image to be displayed, 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 241. In response to the application of the drive voltage, each pixel 241 switches between a state in which light incident on the transmissive portion 241a is transmitted through the polarizer on the output side (ON state) and a state in which light incident on the transmissive portion 241a is absorbed by the polarizer on the output side (OFF state). By distributing the ON-state pixels 241 according to the image data 132, an image according to the image data 132 can be displayed in a transmissive manner. For example, when the display element 24 is driven based on image data 132 according to the image of the arrow shown in FIG. 7, the pixels 241 in the image region R1 shaped like the arrow are turned ON, and light incident on the transmissive portion 241a of each pixel 241 in the image region R1 is transmitted. Furthermore, the pixels 241 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 blocked. When the dot pattern light L2 forming the dot pattern DP shown in FIG. 7 is incident on the display element 24 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. 8. The light of the dot pattern light L2 that is transmitted through the display element 24 is the image light L3 (see FIG. 3). In this manner, the display element 24 generates the 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 projected onto the projection target 2. As a result, the image pattern IP of FIG. 8, consisting of dots D distributed in the shape of an arrow, is projected onto the projection target 2.

[0018] As shown in FIG. 4, the first lens 25 is a microlens arranged on the diffractive optical element 22 side (-Z direction side, incident side) of the display element 24. The multiple first lenses 25 correspond to multiple pixels 241 of the display element 24. That is, one first lens 25 is provided at a position corresponding to one pixel 241. Therefore, the multiple first lenses 25 are arranged in a matrix when viewed from the Z direction. The shape of each first lens 25 when viewed from the Z direction may be circular or approximately rectangular. By making the first lenses 25 approximately rectangular, the occupation area of ​​each first lens 25 can be increased and the light collection efficiency can be improved. Each first lens 25 is a biconvex spherical lens whose lens optical axis is parallel to the optical axis A of the laser light L1. The distance between the pixel 241 and the first lens 25 in the Z direction is determined depending on the focal length of the first lenses 25, and may be, for example, approximately the same as the arrangement pitch of the pixels 241. In FIG. 4, the plurality of contacting first lenses 25 are depicted as separate bodies, but the plurality of contacting first lenses 25 may be integrally connected.

[0019] The second lens 26 is a microlens arranged on the side of the display element 24 opposite to the diffractive optical element 22 side (+Z direction side, output side). The multiple second lenses 26 correspond to the multiple pixels 241 of the display element 24. That is, one second lens 26 is provided for each pixel 241 at a position corresponding to that pixel 241. Therefore, the multiple second lenses 26 are arranged in a matrix when viewed from the Z direction. The shape of each second lens 26 when viewed from the Z direction may be circular or approximately rectangular. By making the second lens 26 approximately rectangular, the occupation area of ​​each second lens 26 can be increased and the light collection efficiency can be improved. Each second lens 26 is a biconvex spherical lens whose lens optical axis is parallel to the optical axis A of the laser light L1. The first lens 25 and the second lens 26 corresponding to the same pixel 241 have the same radius of curvature of the lens surface. Furthermore, the first lens 25 and the second lens 26 corresponding to the same pixel 241 may have the same size as viewed in the Z direction (the direction of the optical axis A). Here, the size may be the maximum width of the shape of the area occupied by the first lens 25 and the second lens 26 as viewed in the Z direction. The distance between the pixel 241 and the second lens 26 in the Z direction is determined according to the focal length of the second lens 26, and may be, for example, approximately the same as the arrangement pitch of the pixels 241. When two or more second lenses 26 are in contact with each other, these two or more contacting second lenses 26 may be connected integrally.

[0020] 4 is a schematic diagram in which the number of pixels 241, first lenses 25, and second lenses 26 is significantly reduced compared to the actual number. In FIG. 4, one pixel 241 through which each branched light of the dot pattern light L2 passes, and the first lens 25 and second lens 26 corresponding to that pixel 241 are depicted. In reality, the pixel 241, the first lens 25, and the second lens 26 are smaller than the diameter of one branched light, and one branched light is incident on multiple pixels 241, first lenses 25, and second lenses 26.

[0021] The first lens 25 and the second lens 26 may be made of the same material. That is, the first lens 25 and the second lens 26 may have the same refractive index. The material of the first lens 25 and the second lens 26 may be, for example, silicon (a synthetic polymer compound containing silicon) or resin (acrylic resin, epoxy resin, polyimide resin, styrene resin, etc.). The substrates 231 and 232 may be made of the same material. The material of the substrates 231 and 232 is not particularly limited as long as it is a transparent material having a refractive index different from that of the first lens 25 and the second lens 26. The material of the substrates 231 and 232 may be, for example, silicon or resin.

[0022] The first lens 25 can be manufactured, for example, by the following method. First, a base material to be the substrate 231 is subjected to processing such as etching to form a recess having the surface shape of one side of the first lens 25, and the material for the first lens 25 is filled into the recess. Similarly, a recess having the surface shape of the other side of the first lens 25 is formed in another base material, and the material for the first lens 25 is filled into the recess. After polishing the surfaces of the obtained base materials, the two base materials are bonded together so that the material for the first lens 25 is bonded, thereby obtaining the substrate 231 having the first lens 25 with a biconvex spherical surface formed therein. In a similar manner, the substrate 232 having the second lens 26 formed therein can be formed.

[0023] As shown in FIG. 4, the display element 24 is arranged such that a plane S on which a plurality of pixels 241 are arranged is perpendicular to the optical axis A of the laser light L1. Also, as shown in FIGS. 4 and 9, one pixel 241, one first lens 25, and one second lens 26, each of whose centers coincide with the optical axis A, are located on the optical axis A. Also, as shown in FIGS. 4 and 10, the position of one of the plurality of first lenses 25 corresponding to a pixel 241 that is at least a predetermined distance d from the optical axis A (hereinafter referred to as a "first position P1") is closer to the optical axis A than the position facing the corresponding pixel 241 (hereinafter referred to as a "facing position P0"). Here, the positions of the first lens 25 and the pixel 241 are the positions of the centers of the first lens 25 and the pixel 241, respectively, as viewed from the Z direction. The facing position P0 is the position of the lens when the center of the first lens 25 coincides with the center of the corresponding pixel 241, as viewed from the Z direction. In this embodiment, the predetermined distance d is less than the arrangement pitch of the pixels 241. Therefore, the first positions P1 of each of the first lenses 25, except for the first lenses 25 on the optical axis A, are shifted in the direction of the optical axis A from the opposing position P0. While FIG. 4 shows the positions of the first lenses 25 in the Y direction in a cross section perpendicular to the X axis, the first positions P1 of the first lenses 25 corresponding to pixels 241 that are at least the predetermined distance d from the optical axis A are also closer to the optical axis A than the opposing position P0 in any direction other than the Y direction. Furthermore, the amount of shift Δ1 of the first positions P1 of the first lenses 25 from the opposing position P0 increases as the angle θ between the optical axis A and the incident direction (optical axis B) of the dot pattern light L2 on the corresponding pixel 241 increases. Therefore, when viewed from the Z direction, the first positions P1 of the multiple first lenses 25 are shifted from the opposing position P0 so as to contract radially inversely toward the optical axis A. Therefore, the matrix formed by the plurality of first lenses 25 has a size obtained by reducing the matrix formed by the plurality of pixels 241 at a predetermined reduction ratio.

[0024] 4 and 10, the position of the second lens 26 corresponding to a pixel 241 that is a predetermined distance d or more away from the optical axis A (hereinafter referred to as the "second position P2") among the multiple second lenses 26 is farther from the optical axis A than the opposing position P0 facing the corresponding pixel 241. Here, the position of the second lens 26 is assumed to be the center position of the second lens 26 when viewed from the Z direction. Since the predetermined distance d is less than the arrangement pitch of the pixels 241, the second position P2 of each second lens 26 except for the second lens 26 on the optical axis A is shifted in the opposite direction to the optical axis A from the opposing position P0. FIG. 4 shows the position of the second lens 26 in the Y direction on a cross section perpendicular to the X axis, but also in any direction other than the Y direction, the second position P2 of the second lens 26 corresponding to a pixel 241 that is a predetermined distance d or more away from the optical axis A is farther from the optical axis A than the opposing position P0. Furthermore, the amount of deviation Δ2 of the second position P2 of the second lens 26 from the opposing position P0 increases as the angle θ between the optical axis A and the incident direction (optical axis B) of the dot pattern light L2 to the corresponding pixel 241 increases. Therefore, when viewed from the Z direction, the second positions P2 of the multiple second lenses 26 are shifted from the opposing position P0 so as to spread radially around the optical axis A. Therefore, the size of the matrix formed by the multiple second lenses 26 is equivalent to the size of the matrix formed by the multiple pixels 241 enlarged at a predetermined magnification rate.

[0025] The predetermined distance d may be equal to or greater than the arrangement pitch of the pixels 241. In this case, the positions of the plurality of first lenses 25 and second lenses 26 corresponding to the plurality of pixels 241 within the range of the predetermined distance d from the optical axis A will be the opposing position P0. Furthermore, if there are no pixels 241, first lenses 25, or second lenses 26 whose centers coincide with the optical axis A, the predetermined distance d may be set to 0. In other words, the positions of all of the first lenses 25 and second lenses 26 may be shifted according to the distance from the optical axis A.

[0026] Each of the multiple first lenses 25 arranged in this manner focuses the incident dot pattern light L2 onto the transmission portion 241a of the corresponding pixel 241. Furthermore, each of the multiple second lenses 26 refracts the light that has been focused by the first lens 25 and transmitted through the transmission portion 241a of the corresponding pixel 241 so as to return it to light having the same directivity as the directivity of the incident dot pattern light L2. Here, "returning it to light having the same directivity" may mean returning it to light having directivity that completely matches the directivity of the incident dot pattern light L2, or may mean returning it to light having directivity that is approximately the same as the directivity within a range that allows the dot pattern DP to be projected onto the projection target 2.

[0027] For example, as shown in FIG. 9, the first lens 25, whose center is on the optical axis A, focuses the dot pattern light L2, which is parallel to the optical axis A, on the transmission portion 241a of the corresponding pixel 241 (the pixel 241 on the optical axis A). The second lens 26, whose center is on the optical axis A, refracts the light focused by the first lens 25 and returns it to the original parallel light. This parallel light becomes the image light L3. The dot pattern light L2 incident on the first lens 25 and the image light L3 emitted from the second lens 26 are parallel to each other. However, the dot pattern light L2 and the image light L3 do not have to be completely parallel, and may be offset from each other by a certain angle. Note that FIG. 9 illustrates only the portion of the branched light of the dot pattern light L2 that is incident on the first lens 25 (the same applies to FIGS. 10 and 12). Furthermore, each focal point F of the first lens 25 and the second lens 26 is located between the first lens 25 and the second lens 26 in the direction parallel to the optical axis A (Z direction). In this embodiment, each focal point F of the first lens 25 and the second lens 26 corresponding to the same pixel 241 is located inside the transmission portion 241a of the corresponding pixel 241. Furthermore, each focal point F of the first lens 25 and the second lens 26 on the optical axis A is at the same position inside the transmission portion 241a.

[0028] As shown in FIG. 10 , the first lens 25, which corresponds to a pixel 241 that is at least a predetermined distance d from the optical axis A and whose first position P1 is offset from the opposing position P0 toward the optical axis A, focuses the dot pattern light L2 incident along the optical axis B that is tilted relative to the optical axis A at a focusing point inside the transmissive portion 241a of the pixel 241. The second lens 26, whose second position P2 is offset from the opposing position P0 toward the opposite side of the optical axis A, refracts the light focused by the first lens 25 and returns it to parallel light parallel to the original optical axis B. This parallel light becomes the image light L3. The first position P1 and the second position P2 may be located on the optical axis B. In FIG. 10 as well, the focal points F (not shown in FIG. 10 ) of the first lens 25 and the second lens 26 are located between the first lens 25 and the second lens 26 that correspond to the same pixel 241 in the Z direction.

[0029] 4, the optical axis of the first lens 25 (hereinafter referred to as the "first lens optical axis C1") and the optical axis of the second lens 26 (hereinafter referred to as the "second lens optical axis C2") may be tilted from a direction parallel to the optical axis A. Specifically, the first lens optical axis C1 of the first lens 25 corresponding to the pixel 241 that is a predetermined distance d or more away from the optical axis A, and the second lens optical axis C2 of the second lens 26 corresponding to this pixel 241 are tilted in a direction away from the optical axis A as the first lens optical axis C1 and the second lens optical axis C2 move toward the traveling direction of the laser light L1 (+Z direction) with respect to a direction parallel to the optical axis A. Furthermore, the angle between the first lens optical axis C1 of the first lens 25 and the optical axis A, and the angle between the second lens optical axis C2 of the second lens 26 and the optical axis A, become larger as the angle θ (see FIG. 12) between the optical axis A and the incident direction (direction of optical axis B) of the dot pattern light L2 to the pixel 241 corresponding to the first lens 25 and the second lens 26 becomes larger. In other words, the farther the first lens 25 and the second lens 26 corresponding to the pixel 241 are from the optical axis A, the larger the inclination angle of the first lens optical axis C1 and the second lens optical axis C2 with respect to the direction parallel to the optical axis A.

[0030] 12, the first lens optical axis C1 of the first lens 25 and the second lens optical axis C2 of the second lens 26 may be parallel to the incident direction (optical axis B) of the dot pattern light L2 to the corresponding pixel 241. In this case, the focal points F of the first lens 25 and the second lens 26 are located inside the transmission portion 241a of the pixel 241, and the respective focal points F are at the same position.

[0031] Depending on the direction of the optical axis B of the dot pattern light L2, the size of the pixel 241, the focal length and size of the first lens 25 and the second lens 26, etc., it is possible to tilt only the first lens optical axis C1 and the second lens optical axis C2 from a direction parallel to the optical axis A without shifting the first position P1 of each first lens 25 and the second position P2 of each second lens 26 from the opposing position P0.

[0032] As described above, the projection device 1 according to this embodiment includes the light source 21 that emits laser light L1, the diffractive optical element 22 that converts the laser light L1 emitted from the light source 21 into dot pattern light L2 that has a predetermined directivity and forms a predetermined pattern on the projection target 2, the display element 24 having pixels 241 each composed of a transmissive portion 241a that transmits light and an opaque portion 241b that does not transmit light, and on which the dot pattern light L2 is incident, the first lens 25 that is disposed on the diffractive optical element 22 side of the display element 24 and corresponds to the pixel 241, and the second lens 26 that is disposed on the opposite side of the diffractive optical element 22 side of the display element 24 and corresponds to the pixel 241. The first lens 25 focuses the incident dot pattern light L2 onto the transmissive portion 241a of the corresponding pixel 241, and the second lens 26 refracts the light that has been focused by the first lens 25 and transmitted through the transmissive portion 241a of the corresponding pixel 241, so as to return it to light having the above-mentioned directivity. By providing the display element 24, the projected image can be changed without replacing the diffractive optical element 22. Furthermore, the focusing effect of the first lens 25 allows a portion of the dot pattern light L2 that would otherwise be blocked by the non-transmitting portion 241b to be guided to the transmitting portion 241a and transmitted as image light L3. This increases the brightness of the image light L3. Furthermore, the refraction effect of the second lens 26 causes the image light L3 to have the same directivity as the dot pattern light L2 incident on the pixel 241. That is, the image light L3 becomes parallel light with a directivity such that the beam diameter is approximately constant at each position on the optical path. This allows the projection target 2 to be focused regardless of its position in the Z direction. These features enable the projection of a wide-angle, high-brightness, and highly visible image. Furthermore, because the image is projected onto the projection target 2 in a focused state regardless of the distance from the projection device 1 to the projection target 2, there is no need to provide any optical components for focusing, other than the first lens 25 and the second lens 26. This allows the projection device 1 to be made smaller, lighter, and less expensive.

[0033] The display element 24 has a plurality of pixels 241, and is arranged such that a plane S on which the plurality of pixels 241 are arranged is perpendicular to the optical axis A of the laser light L1. The projection device 1 also includes a plurality of first lenses 25 corresponding to the plurality of pixels 241, and a plurality of second lenses 26 corresponding to the plurality of pixels 241. Of the plurality of first lenses 25, a first position P1 of the first lens 25 corresponding to a pixel 241 that is a predetermined distance d or more away from the optical axis A is closer to the optical axis A than a facing position P0 that faces the corresponding pixel 241. Of the plurality of second lenses 26, a second position P2 of the second lens 26 corresponding to a pixel 241 that is a predetermined distance d or more away from the optical axis A is farther from the optical axis A than the facing position P0. In this way, by shifting the first position P1 of the first lens 25 and the second position P2 of the second lens 26 to the opposite side relative to the opposing position P0, the dot pattern light L2 incident obliquely to the optical axis A can be effectively focused onto the transmitting portion 241a and returned to parallel light.

[0034] Moreover, the amount of deviation of the first position P1 and the second position P2 from the opposing position P0 increases as the angle θ between the incident direction of the dot pattern light L2 on the corresponding pixel 241 and the optical axis A increases. This makes it possible to effectively collect the dot pattern light L2 on the transmission portion 241a and return it to parallel light, regardless of the incident angle of the dot pattern light L2.

[0035] Furthermore, the first lens optical axis C1 of the first lens 25 among the plurality of first lenses 25 corresponding to the pixel 241 that is at least a predetermined distance d away from the optical axis A, and the second lens optical axis C2 of the second lens 26 among the plurality of second lenses 26 corresponding to the pixel 241 that is at least a predetermined distance d away from the optical axis A, may be inclined in a direction parallel to the optical axis A such that the first lens optical axis C1 and the second lens optical axis C2 move away from the optical axis A as they move toward the traveling direction of the laser light L1. This can increase the light-collection efficiency by the first lens 25 of the dot pattern light L2 that is incident obliquely with respect to the optical axis A, and can also increase the parallelism of the image light L3 after passing through the second lens 26.

[0036] Furthermore, the angle between the first lens optical axis C1 of the first lens 25 and the optical axis and the angle between the second lens optical axis C2 of the second lens 26 and the optical axis may increase as the angle θ between the optical axis and the incident direction of the dot pattern light L2 on the pixels 241 corresponding to the first lens 25 and the second lens 26 increases. This makes it possible to increase the light-collection efficiency of the first lens 25 regardless of the incident angle of the dot pattern light L2, and to increase the parallelism of the image light L3 after passing through the second lens 26.

[0037] Furthermore, the first lens optical axis C1 of the first lens 25 and the second lens optical axis C2 of the second lens 26 may be parallel to the direction of incidence of the dot pattern light L2 on the corresponding pixel 241. This allows the dot pattern light L2, which is incident obliquely with respect to the optical axis A, to be most efficiently collected onto the transmission portion 241a by the first lens 25. Furthermore, the parallelism of the image light L3 after passing through the second lens 26 can be most effectively increased.

[0038] Furthermore, the focal point F of the first lens 25 and the focal point F of the second lens 26 corresponding to the same pixel 241 as the first lens 25 are located between the first lens 25 and the second lens 26 in the direction parallel to the optical axis A of the laser light L1. This allows the dot pattern light L2 to be condensed inside the transmission portion 241a. Therefore, by arranging the first lens 25 and the second lens 26 symmetrically with respect to this condensing position, the beam diameter of the dot pattern light L2 incident on the first lens 25 and the beam diameter of the image light L3 emitted from the second lens 26 can be made the same. This allows the image light L3 to be emitted while maintaining the beam diameter and directivity of the dot pattern light L2, while increasing the luminance of the image light L3.

[0039] Furthermore, the first lens 25 and the second lens 26 corresponding to the same pixel 241 have the same refractive index and surface radius of curvature. This makes it possible to make the beam diameter of the dot pattern light L2 incident on the first lens 25 and the beam diameter of the image light L3 emitted from the second lens 26 the same, and to emit image light L3 having the same directivity as the dot pattern light L2.

[0040] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the laser light L1 is used as an example of coherent light, but the present invention is not limited to this, and any light may be used as long as it is light with a uniform phase and interferes with the diffractive optical element 22. For example, instead of the light source 21 of the laser light L1, an LED (Light Emitting Diode) configured to emit light with a uniform phase may be used.

[0041] Although the diffractive optical element 22 that generates the dot pattern light L2 as the pattern light has been exemplified, the diffractive optical element 22 is not limited to this. For example, the diffractive optical element 22 may generate a pattern light including straight lines, a solid pattern light of a predetermined range, or the like.

[0042] The first lens 25 may be a plano-convex lens having a spherical incident surface for the dot pattern light L2 and a flat surface on the opposite side (exit side) from the incident surface. The second lens 26 may be a plano-convex lens having a flat incident surface for the light transmitted through the pixel 241 and a spherical surface on the opposite side (exit side) from the incident surface.

[0043] Furthermore, in the above embodiment, a configuration has been exemplified in which the first lens 25 and the second lens 26 are formed inside the substrates 231 and 232 of the display panel 23, respectively, but the configuration is not limited to that of the embodiment as long as the first lens 25 can focus the dot pattern light L2 on the transmission portion 241a of the pixel 241 and the second lens 26 can refract the transmitted light into parallel light. For example, if the substrates 231 and 232 are extremely thin (for example, several hundred μm), the first lens 25 and the second lens 26 may be disposed outside the display panel 23.

[0044] In the above embodiment, the radius of curvature of the surfaces of all first lenses 25 is the same, and the radius of curvature of the surfaces of all second lenses 26 is the same, but this is not limiting. For example, the radius of curvature of the surfaces of each first lens 25 and each second lens 26 may be set to a value corresponding to the distance from the optical axis A of each lens.

[0045] Furthermore, in the above embodiment, a configuration in which one first lens 25 and one second lens 26 correspond to one pixel 241 (one transmissive portion 241a) has been exemplified, but this is not limiting. For example, two or more (plural) pixels 241 (two or more transmissive portions 241a) may correspond to one first lens 25, and one second lens 26 may correspond to two or more pixels 241. In other words, light collected by one first lens 25 may be incident on two or more transmissive portions 241a in two or more pixels 241, and light transmitted through two or more transmissive portions 241a in two or more pixels 241 may be incident on one second lens 26. Furthermore, two or more first lenses 25 may correspond to one pixel 241, and two or more second lenses 26 may correspond to one pixel 241. In other words, light collected by two or more first lenses 25 may be incident on one transmitting portion 241a in one pixel 241, and light transmitted through one transmitting portion 241a in one pixel 241 may be incident on two or more second lenses 26. Furthermore, in an area less than a predetermined distance d from the optical axis A, one pixel 241 may correspond to one first lens 25 and one second lens 26, and in an area away from the optical axis A by the predetermined distance d or more, one pixel 241 may correspond to two or more first lenses 25 and / or two or more second lenses 26. In other words, in areas where the angle θ between the incident direction of the dot pattern light L2 to the pixel 241 and the optical axis A is less than a predetermined angle, one pixel 241 corresponds to one first lens 25 and one second lens 26, and in areas where the angle θ is equal to or greater than the above-mentioned predetermined angle, one pixel 241 may correspond to two or more first lenses 25 and / or two or more second lenses 26.

[0046] Furthermore, while the display element 24 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, 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 data as the image data 132, such that the pixel value of each pixel can take on the number of gradations displayed by the liquid crystal panel. Furthermore, the display element is not limited to a liquid crystal display element, and may be any transmissive, non-self-luminous display element.

[0047] In the above embodiment, a monochromatic image is projected using laser light emitted from one light source 21. 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 20 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 22. 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 22. 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 22. 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 24 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.

[0048] 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.

[0049] 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]

[0050] 1...projection device, 21...light source, 22...diffractive optical element, 24...display element, 25...first lens, 26...second lens, 241...pixel, 241a...transmissive portion, 241b...non-transmissive portion, d...predetermined distance, L1...laser light (coherent light), L2...dot pattern light (pattern light)

Claims

1. a light source that emits coherent light; a diffractive optical element that converts the coherent light emitted from the light source into pattern light that has a predetermined directivity and forms a predetermined pattern on a projection target; a display element having pixels each composed of a transmissive portion that transmits light and a non-transmissive portion that does not transmit light, and on which the pattern light is incident; a first lens disposed on the diffractive optical element side of the display element and corresponding to the pixel; a second lens disposed on the opposite side of the display element from the diffractive optical element side and corresponding to the pixel; Equipped with the first lens focuses the incident pattern light onto the transmission portion of the corresponding pixel; the second lens refracts the light that has been collected by the first lens and transmitted through the transmission portion of the corresponding pixel so as to return it to the light having the directionality; Projection device.

2. the display element has a plurality of the pixels, and is arranged at an angle such that a plane on which the plurality of pixels are arranged is perpendicular to an optical axis of the coherent light, the projection device includes a plurality of the first lenses corresponding to the plurality of pixels and a plurality of the second lenses corresponding to the plurality of pixels; a first position of a first lens corresponding to a pixel that is a predetermined distance or more away from the optical axis among the plurality of first lenses is closer to the optical axis than a position facing the corresponding pixel; a second position of the second lens corresponding to the pixel that is at least the predetermined distance away from the optical axis is farther from the optical axis than a position facing the corresponding pixel, among the plurality of second lenses; The projection device according to claim 1 .

3. the deviation amounts of the first position and the second position from the positions facing the corresponding pixels are larger as the angle formed between the incident direction of the pattern light on the corresponding pixels and the optical axis is larger; 3. The projection device according to claim 2.

4. the display element has a plurality of the pixels, and is arranged at an angle such that a plane on which the plurality of pixels are arranged is perpendicular to an optical axis of the coherent light, the projection device includes a plurality of the first lenses corresponding to the plurality of pixels and a plurality of the second lenses corresponding to the plurality of pixels; a first lens optical axis of a first lens among the plurality of first lenses that corresponds to the pixel that is away from the optical axis by a predetermined distance or more, and a second lens optical axis of a second lens among the plurality of second lenses that corresponds to the pixel that is away from the optical axis by the predetermined distance or more, the first lens optical axis and the second lens optical axis are inclined in a direction away from the optical axis with respect to a direction parallel to the optical axis as they move toward a traveling direction of the coherent light, The projection device according to claim 1 .

5. an angle formed between the first lens optical axis of the first lens and the optical axis and an angle formed between the second lens optical axis of the second lens and the optical axis are larger as an angle formed between the optical axis and an incident direction of the pattern light to the pixels corresponding to the first lens and the second lens is larger; 5. The projection device according to claim 4.

6. the first lens optical axis of the first lens and the second lens optical axis of the second lens are parallel to an incident direction of the pattern light to the corresponding pixel; 5. The projection device according to claim 4.

7. a focal point of the first lens and a focal point of the second lens corresponding to the same pixel as the focal point of the first lens are located between the first lens and the second lens in a direction parallel to an optical axis of the coherent light; The projection device according to claim 1 .

8. the first lens and the second lens corresponding to the same pixel have the same refractive index and the same radius of curvature of their surfaces; The projection device according to claim 1 .

Images