Projection device, projection method, and program

Abstract

The goal is to achieve both image projection and illumination projection simultaneously. [Solution] The projection device comprises a light source unit 31, a diffractive optical element 51, a display element 61, a polymer-dispersed liquid crystal unit 62, and a control unit. The light source unit 31 includes laser diodes 31R, 31G, and 31B that emit light in a predetermined wavelength band. The diffractive optical element 51 diffracts the light emitted from the laser diodes 31R, 31G, and 31B. The display element 61 transmits at least a portion of the light diffracted by the diffractive optical element 51 to form an image. The control unit switches between diffusion and transmission of the light transmitted through the display element 61 that is incident on the polymer-dispersed liquid crystal unit 62.

Description

[Technical Field]

[0001] The present invention relates to a projection apparatus, a projection method, and a program. [Background Art]

[0002] Conventionally, a projection apparatus including an LD (Laser Diode) light source and a DOE (Diffractive Optical Element) is known. The projection apparatus forms planar light composed of multiple bright spots by using multiple orders of diffracted light based on the DOE. The projection apparatus causes the planar light to pass through a display element such as an LCD (Liquid Crystal Display) and projects a pattern onto a display target. Since the projection apparatus projects coherent laser light, it can achieve wide-angle, compact, lightweight, high-brightness, and focus-free (in-focus anywhere) display even without a projection optical system.

[0003] There is also known an illumination apparatus that expands laser light emitted from a laser light source with a magnifying lens, converts the expanded laser light into parallel illumination light with a collimating lens, and projects a hologram reproduced image via a diffractive optical element (see Patent Document 1). [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] International Publication No. 2018 / 135396 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, although the illumination apparatus of Patent Document 1 can project a hologram reproduced image, it cannot project illumination light as diffused light.

[0006] An object of the present invention is to achieve both image projection and illumination light projection. [Means for Solving the Problem]

[0007] To solve the above problems, the projection apparatus of the present invention comprises a light source unit including a light source that emits light in a predetermined wavelength band, a diffractive optical element that diffracts the light emitted from the light source, a mask unit that transmits or reflects at least a portion of the light diffracted by the diffractive optical element to form an image, a polymer-dispersed liquid crystal unit, and a control unit that switches between diffusion and transmission of light transmitted or reflected by the mask unit that is incident on the polymer-dispersed liquid crystal unit. [Effects of the Invention]

[0008] This invention makes it possible to achieve both image projection and illumination light projection simultaneously. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the image projection unit and the object to be displayed in a projection device according to an embodiment of the present invention. [Figure 2] This is a block diagram showing the functional configuration of a projection device. [Figure 3] This is a flowchart showing the image display process. [Figure 4] This is a diagram showing illumination light. [Figure 5] This is a diagram showing an image. [Figure 6] This is a diagram showing an image. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the scope of the present invention is not limited to the illustrated examples.

[0011] First, the configuration of the apparatus in this embodiment will be described with reference to Figures 1 and 2. As shown in Figures 1 and 2, the projection apparatus 1 of this embodiment includes an image projection unit 20, and projects projection light L onto the display target object 2 to display (project) various images onto the surface of the display target object 2. The display target object 2 may be, for example, a screen, or the wall, floor or ceiling of a building, an exterior object of a car, or the surface of any object. In this embodiment, the distance from the projection apparatus 1 (image projection unit 20) to the display target object 2 is, for example, about 1m to 10m, but is not limited thereto. The image projected onto the surface of the display target object 2 is not particularly limited, but may be, for example, an image of a guide sign to guide people in the vicinity, or an image to decorate the surface of the display target object 2. In addition, the projection apparatus 1 can project illumination light L1 onto the display target object 2 using the image projection unit 20. The illumination light L1 is scattered light and is more diffused on the display target object 2 than the projection light L, so the illumination range is wider.

[0012] As shown in Figure 1, the image projection unit 20 includes a light source unit 31, a prism unit 41, a diffractive optical element 51, a display element 61, and a polymer-dispersed liquid crystal unit 62. Also, Figure 1 has a three-dimensional x, y, and z axis. The light source unit 31 includes laser diodes 31G, 31R, 31B and a light source driving circuit. The laser diodes 31G, 31R, and 31B function as the first, second, and third light sources, respectively. The prism unit 41 functions as an optical path conversion unit. The display element 61 functions as a mask unit. The laser diode 31G is a light source that emits green (G) laser light (hereinafter referred to as G light). The laser diode 31R is a light source that emits red (R) laser light (hereinafter referred to as R light). The laser diode 31B is a light source that emits blue (B) laser light (hereinafter referred to as B light). The laser diodes 31G, 31R, and 31B are arranged sequentially in the +x direction so that each emits laser light in the -z direction. The light source drive circuit of the light source unit 31 independently turns on and off each of the laser diodes 31G, 31R, and 31B according to the control of the control unit 11 (Figure 2).

[0013] The prism section 41 has prisms 411, 412, and 413. Prism 411 has a mirror section 411G formed on the slanted surface of the triangular prism. Mirror section 411G is a mirror with high reflectivity [%] across the entire wavelength band (at least the green wavelength band) (total internal reflection). Mirror section 411G reflects the G light incident from the laser diode 31G in the +x direction. Prism 412 has a mirror section 412R formed on the slanted surface of the triangular prism. Mirror section 412R is a dichroic mirror with high reflectivity [%] in the red wavelength band and low reflectivity [%] in wavelength bands other than red. Mirror section 412R reflects the R light incident from the laser diode 31R in the +x direction and transmits the G light incident from prism 411 in the +x direction. Prism 413 has a mirror section 413B formed on the slanted surface of the triangular prism. The mirror section 413B is a dichroic mirror with a high reflectivity [%] in the blue wavelength band and a low reflectivity [%] in wavelength bands other than blue. The mirror section 413B reflects the B light incident from the laser diode 31B in the +x direction and transmits the G light and R light incident from the prism 412 in the +x direction. The prism section 41, which serves as the optical path conversion section, may be configured such that the mirror sections 411G, 412R, and 413B are each arranged on a transparent plate.

[0014] The diffractive optical element 51 is a diffraction grating (DOE) having a three-dimensional uneven structure formed by combining multiple diffraction gratings with different grating periods. The diffractive optical element 51 diffracts the incident laser light according to the pitch of multiple grating periods and emits multiple-order diffracted light consisting of a dot pattern of multiple bright spots where the diffracted light from the matrix-like (griddle-like) pattern interferes and reinforces each other. The diffractive optical element 51 is arranged perpendicular to the optical axis L0. The display element 61 is a transmissive liquid crystal display element arranged perpendicular to the optical axis L0. The display element 61 has a dot-matrix type liquid crystal panel (LCD) in which pixels are arranged in a matrix, polarizing plates arranged on both sides so as to sandwich the liquid crystal panel, and a liquid crystal driving circuit that drives the liquid crystal panel. The liquid crystal panel is, for example, a TN (Twisted Nematic) type or an STN (Super TN) type liquid crystal panel. The liquid crystal driving circuit, under the control of the control unit 11, applies a driving voltage to each pixel according to the pixel value of the image to be projected (displayed), based on the image data stored in the memory unit 13 (Figure 2), thereby controlling the orientation state of the liquid crystal layer of each pixel. In response to the application of the driving voltage, each pixel switches between a state in which light incident on the pixel is transmitted through the polarizing plate on the exit side (on state) and a state in which light incident on the pixel is absorbed by the polarizing plate on the exit side (off state). The display element 61 displays the image by distributing the on-state pixels based on the image data, transmitting the image data, and projecting the transmitted light onto the display object 2. The display element 61 has a configuration in which all pixels are in the off state of light absorption, or a configuration in which all pixels are in the on state of light transmission, when unpowered (no driving voltage applied).

[0015] The polymer-dispersed liquid crystal section 62 is a polymer-dispersed liquid crystal. A polymer-dispersed liquid crystal is a liquid crystal system that utilizes the fact that liquid crystals take on a phase-separated structure within a polymer matrix. In a polymer-dispersed liquid crystal, when no electric field is applied, the orientation vectors of the dispersed liquid crystal droplets are oriented in different directions, causing light to scatter at the interface and creating an opaque white state. When light is incident on the polymer-dispersed liquid crystal section 62 in its opaque state, the incident light is diffused and emitted, making it appear as if the polymer-dispersed liquid crystal section 62 itself is emitting light from the surface. Conversely, by applying an electric field to the polymer-dispersed liquid crystal, the refractive indices of the polymer and liquid crystal become almost equal, resulting in a transparent state. The polymer-dispersed liquid crystal section 62, under the control of the control unit 11, transmits or scatters diffracted light incident from the display element 61 and emits it as illumination light.

[0016] As shown in Figure 2, the projection device 1 includes a control unit 11, an operation unit 12, a storage unit 13, a communication unit 14, an audio output unit 15, an image projection unit 20, and the like. The image projection unit 20 includes a light source unit 31, an optical system 40, a diffractive optical element 51, a display element 61, a polymer-dispersed liquid crystal unit 62, and the like. The optical system 40 includes a prism unit 41. All parts of the projection device 1, except for the optical system 40 and the diffractive optical element 51, are connected via a bus 16. The projection device 1 may further include other components, such as a display unit that displays status information of the projection device 1.

[0017] The control unit 11 has a CPU (Central Processing Unit) and RAM (Random Access Memory) and controls each part of the projection device 1. The CPU of the control unit 11 reads various programs stored in the memory unit 13, loads them into the RAM, and executes various processes in cooperation with the loaded programs. The RAM is a volatile semiconductor memory that temporarily stores programs and data, and a work area is formed therein. The operation unit 12 has buttons, a remote control and its receiver, and receives various operation inputs from the user and outputs the operation information to the control unit 11.

[0018] The storage unit 13 is configured of a flash memory or the like, is a readable and writable non-volatile memory, and stores various programs and various data. In particular, the storage unit 13 stores an image display program for executing image display processing described later. Further, the storage unit 13 can store image data and the like received from an external device via the communication unit 14 under the control of the control unit 11. The communication unit 14 is a communication module for performing wired communication with an external device such as a PC (Personal Computer) in accordance with a communication standard such as USB (Universal Serial Bus). The CPU 11 transmits and receives information to and from an external device via the communication unit 14. For example, the external device transmits image data for projection to the projection apparatus 1. Further, the communication unit 14 may be a communication module for performing wireless communication with an external device in accordance with a communication standard such as a wireless LAN (Local Area Network). The audio output unit 15 includes an amplifier, a speaker, and the like, and outputs various types of audio based on, for example, audio data stored in the storage unit 13 under the control of the control unit 11.

[0019] Next, the operation of the projection apparatus 1 will be described with reference to FIG. 3. The image display process is a process of projecting an image or illumination light. Image data including color information of an image for projection is stored in the storage unit 13 in advance. The color information is any one of red, green, and blue. In the projection apparatus 1, triggered by input of an execution instruction for image display processing from a user via, for example, the operation unit 12, the control unit 11 executes the image display processing based on the image display program stored in the storage unit 13. Here, an example in which the image display processing performs image display (projection) and does not perform audio output will be described, but the present invention is not limited thereto, and a configuration for performing the audio output may be adopted.

[0020] As shown in Figure 3, the control unit 11 receives instruction information from the user via the operation unit 12 for image display (projection) or projection of illumination light and color information of the illumination light, and sets the temporal light emission pattern of the light source unit 31 corresponding to the instruction information (step S11). The light emission pattern is continuous light emission when projecting an image or illumination light. In step S11, when displaying an image, the control unit 11 reads image data including the color information of the instructed image from the storage unit 13, and the light emission pattern corresponds to the color information. When projecting an image, the light emission pattern is red, green, or blue light emission (laser diodes 31R, 31G, or 31B). When projecting illumination light, the light emission pattern is simultaneous red, green, and blue light emission (laser diodes 31R, 31G, and 31B). Due to the simultaneous light emission of laser diodes 31R, 31G, and 31B, white laser light is emitted from the prism unit 41. Then, based on the instruction information in step S11, the control unit 11 determines whether or not to project illumination light (step S12). If illumination light is to be projected (step S12; YES), the control unit 11 starts scattering control to scatter the incident light without applying a voltage to the polymer-dispersed liquid crystal section 62 (step S13). Then, the control unit 11 starts transparency control to transmit the incident light to the display element 61 (step S14).

[0021] When no illumination light is projected (an image is projected (displayed)) (step S12; NO), the control unit 11 applies an applied voltage to the polymer-dispersed liquid crystal unit 62 and starts transparency control for transmitting incident light (step S15). Then, the control unit 11 starts generation control of an image (mask) of a color corresponding to the image data instructed in step S11 for the display element 61 (step S16). Then, the control unit 11 causes the laser diodes 31G, 31R or 31B of the light source unit 31 corresponding to the currently set light emission pattern to emit light for a predetermined time (step S17). Then, the control unit 11 determines whether or not to change the light emission pattern after instruction information for changing the light emission pattern (image display or illumination light projection) is input by a user via the operation unit 12 (step S18). When the light emission pattern is to be changed (step S18; YES), the process proceeds to step S11. When the light emission pattern is not to be changed (step S18; NO), the control unit 11 determines whether or not to end the image display processing after an instruction to end the image display processing is input by a user via the operation unit 12, for example (step S19). When the image display processing is not to be ended (step S19; NO), the process proceeds to step S17. When the image display processing is to be ended (step S19; YES), the image display processing ends.

[0022] As shown in Figure 4, illumination light 70 is described as an example of projected illumination light. Since illumination light 70 is scattered light (diffuse light), the illumination range is wide and dots due to diffraction are not visible. The color of illumination light 70 corresponds to the white laser light emitted simultaneously by the laser diodes 31R, 31G, and 31B emitted from the light source unit 31. The object to which the illumination light 70 is displayed is, for example, the floor and walls of a passageway in the store "AA Store," which is used as a normal passageway under normal circumstances and as an evacuation route in emergencies such as fire. Under normal circumstances, the illumination light 70 is projected onto the passageway as white normal illumination. For example, when the laser diodes 31R, 31G, and 31B emit light simultaneously, the white light synthesized by the prism unit 41 is transmitted through the transparently controlled diffractive optical element 51. It is also transmitted through the transparently controlled display element 61 and scattered by the polymer-dispersed liquid crystal unit 62, so that the illumination light 70 is displayed on the object to be displayed (passageway). The color of the illumination light 70 may be red, green, or blue by controlling the emission of laser diodes 31R, 31G, or 31B. Furthermore, the color of the illumination light 70 may be a mixture of two colors from red, green, and blue by simultaneously controlling the emission of two of the laser diodes 31R, 31G, or 31B. For example, simultaneous emission control of laser diodes 31R and 31G results in the illumination light 70 being yellow.

[0023] As shown in Figure 5, Image 80 is described as an example of an image that is displayed (projected). Image 80 is a guided image used in the aisle of the store "AA Store" during normal times and when route guidance is in place. Image 80 is an image of blue letters and arrows indicating normal times, and is actually composed of multiple blue dots of a dot matrix. For example, the laser diode 31B emits light, which is diffracted by the diffractive optical element 51 into the light of the dot matrix. The diffracted light is then transmitted through the blue image (mask) generated by the display element 61, and then through the transparently controlled polymer-dispersed liquid crystal section 62, and Image 80 is displayed on the display target (aisle).

[0024] As shown in Figure 6, Image 90 is described as an example of an image that is displayed (projected). Image 90 is an image for guiding evacuation routes in an emergency in the aisle of the store "AA Store". Image 90 is an image of red letters and arrows indicating an emergency, and is actually composed of multiple red dots of a dot matrix. For example, the laser diode 31R emits light, which is diffracted by the diffractive optical element 51 into the light of the dot matrix. The diffractive light is then transmitted through the red image (mask) generated by the display element 61, and then through the transparently controlled polymer-dispersed liquid crystal part 62, and Image 90 is displayed on the display target object (aisle). The illumination light 70 has a wider illumination range than Images 80 and 90. Note that the determination of whether or not to change the light emission pattern by the control unit 11 is not limited to the input of instruction information via the operation unit 12 performed by the user. For example, the control unit 11 may automatically switch depending on whether the brightness of the ambient light is above or below a threshold. In this case, the image can be projected during bright times such as daytime, and the illumination light can be projected during dark times such as nighttime. Alternatively, the control unit 11 can automatically switch depending on whether or not it is within a predetermined time period. During times when people are moving around in offices or schools, such as during commuting hours, or before and after events, it projects routes and destinations, while at other times it projects illumination light. Alternatively, it can automatically switch depending on whether or not there is input data. If there is input data, it projects the input data; if there is no input data, it projects illumination light.

[0025] As described above, according to this embodiment, the projection device 1 comprises a light source unit 31, a diffractive optical element 51, a display element 61, a polymer-dispersed liquid crystal unit 62, and a control unit 11. The light source unit 31 includes laser diodes 31R, 31G, and 31B that emit light in a predetermined wavelength band. The diffractive optical element 51 diffracts the light emitted from the laser diodes 31R, 31G, and 31B. The display element 61 transmits at least a portion of the light diffracted by the diffractive optical element 51 to form an image. The control unit 11 switches between diffusion and transmission of the light transmitted through the display element 61 that is incident on the polymer-dispersed liquid crystal unit 62. Therefore, it is possible to achieve both image projection (display) by the display element 61 and illumination light projection by the polymer-dispersed liquid crystal unit 62. Furthermore, because components can be shared due to this compatibility, the projection device 1 can be made smaller and lighter. In addition, it is possible to project wide-angle, high-brightness, and focus-free (focus can be achieved anywhere) images.

[0026] The light source unit 31 includes laser diodes 31R, 31G, and 31B, which are laser light sources with different wavelength bands. Laser diode 31R emits red light in the first wavelength band. Laser diode 31G emits green light in the second wavelength band. Laser diode 31B emits blue light in the third wavelength band. Therefore, images and illumination lights of red, green, blue, or mixtures thereof can be projected.

[0027] The projection device 1 includes a prism section 41 that converts the optical path of incident light in a predetermined wavelength band and emits it to the diffractive optical element 51. The prism section 41 is positioned in the optical path between the light source section 31 and the diffractive optical element 51. This allows the light source section 31 of the projection device 1 to be positioned appropriately, enabling further miniaturization and weight reduction of the projection device 1. Furthermore, the display element 61 is a liquid crystal panel. Therefore, images can be easily formed (generated).

[0028] When projecting illumination light, the control unit 11 starts scattering control to scatter incident light without applying a voltage to the polymer-dispersed liquid crystal section 62, and starts transparency control to transmit incident light to the display element 61. When projecting an image, the control unit 11 applies a voltage to the polymer-dispersed liquid crystal section 62 to start transparency control to transmit incident light, and starts generating a color mask corresponding to the image data for the display element 61. As a result, when projecting illumination light, the illumination light can be projected appropriately without being blocked, and when projecting an image, an image of the appropriate color can be projected.

[0029] The above description discloses an example in which flash memory is used as a computer-readable medium for the program according to the present invention, but the invention is not limited to this example. Other computer-readable mediums that can be used include non-volatile memory such as HDDs (Head Disk Drives) and SSDs (Solid State Drives), and portable recording media such as CD-ROMs. Furthermore, carrier waves can also be used as a medium for providing program data according to the present invention via a communication line.

[0030] The above description of the embodiment is merely an example of the projection apparatus, projection method, and program according to the present invention, and is not limited thereto. For example, in the above embodiment, the light source unit 31 is configured to have laser diodes that emit red, green, and blue light, but is not limited thereto. The light source unit 31 may be configured to have multiple laser diodes that emit light of other colors.

[0031] Furthermore, although the above embodiment describes a configuration in which the projection device 1 emits light from one laser diode in the light source unit 31 when displaying an image, it is not limited to this configuration. The projection device 1 may be configured to emit light from at least two laser diodes in the light source unit 31 simultaneously when displaying an image. Alternatively, the projection device 1 may be configured to emit light from at least two laser diodes in the light source unit 31 in a time-sequential manner using a field sequential emission pattern. The field sequential method is a method of mixing the emitted light in time by switching the emission of laser light of different wavelengths in a short period of time.

[0032] Furthermore, although the above embodiment described a display element 61 that can switch each pixel of the liquid crystal panel between two grayscale states (on and off), it is not limited to this. The display element may also be able to switch each pixel between three or more grayscale states (for example, 256 grayscale states). 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 steps (for example, 256 steps). In this case, the image data should be such that the pixel value of each pixel can take the value of the number of display grayscale levels of the liquid crystal panel.

[0033] Furthermore, although a liquid crystal display element having a liquid crystal panel was described as the display element 61 in the above embodiment, the invention is not limited thereto. The display element may also be a reflective display element such as a DMD (Digital Micromirror Device) that projects an image by reflecting diffracted light from a diffracting optical element. A DMD has a plurality of micro-mirrors arranged in an array, and by switching the tilt angle of each micro-mirror according to the image data, it forms projected light having the image of the object to be projected onto using the reflected light from the plurality of micro-mirrors.

[0034] While embodiments of the present invention have been described, the scope of the present invention is not limited to the embodiments described above, but includes the scope of the invention as described in the claims and its equivalents. [Explanation of Symbols]

[0035] 1 Projection device, 31 Light source unit, 31R, 31G, 31B Laser diodes, 51 Diffractive optical element, 61 Display element, 62 Polymer dispersed liquid crystal unit, Control unit 11

Claims

1. A light source unit including a light source that emits light in a predetermined wavelength band, A diffractive optical element that diffracts light emitted from the light source, A mask portion that transmits or reflects at least a portion of the light diffracted by the diffractive optical element to form an image, Polymer-dispersed liquid crystal part, A control unit that switches between diffusion and transmission of light transmitted or reflected by the mask portion that is incident on the polymer-dispersed liquid crystal portion, A projection device equipped with the following features.

2. The projection apparatus according to claim 1, wherein the light source unit includes a plurality of light sources with different wavelength bands.

3. The light source unit includes a first light source that emits light in a first wavelength band and a second light source that emits light in a second wavelength band. The first wavelength band light is one of red, green, or blue. The projection apparatus according to claim 2, wherein the second wavelength band light is different in color from the first wavelength band light and is one of red, green, or blue.

4. The light source unit includes a third light source that emits a third wavelength band light different from the first wavelength band light and the second wavelength band light, The projection apparatus according to claim 3, wherein the third wavelength band light is one of red, green, or blue.

5. The projection apparatus according to claim 4, wherein the first light source, the second light source, and the third light source are laser light sources.

6. The projection apparatus according to any one of claims 1 to 5, further comprising an optical path conversion unit that converts the optical path of the incident light in the predetermined wavelength band and emits it to the diffractive optical element.

7. The projection apparatus according to claim 6, wherein the optical path conversion unit is arranged in the optical path between the light source unit and the diffractive optical element.

8. The projection apparatus according to claim 1, wherein the mask portion is a liquid crystal panel.

9. A light source unit including a light source that emits light in a predetermined wavelength band, A diffractive optical element that diffracts light emitted from the light source, A mask portion that transmits or reflects at least a portion of the light diffracted by the diffractive optical element to form an image, Polymer-dispersed liquid crystal part, A projection method for a projection device comprising: A projection method including a control step for switching between diffusion and transmission of light transmitted or reflected through the mask portion that is incident on the polymer-dispersed liquid crystal portion.

10. In the control process described above, When projecting illumination light, scattering control is initiated to scatter the incident light without applying a voltage to the polymer-dispersed liquid crystal portion, and transparency control is initiated to transmit the incident light to the mask portion. The projection method according to claim 9, wherein when projecting an image, a voltage is applied to the polymer-dispersed liquid crystal portion to initiate transparency control that transmits incident light, and control is initiated to generate a mask of a color corresponding to the image data for the mask portion.

11. A light source unit including a light source that emits light in a predetermined wavelength band, A diffractive optical element that diffracts light emitted from the light source, A mask portion that transmits or reflects at least a portion of the light diffracted by the diffractive optical element to form an image, Polymer-dispersed liquid crystal part, A computer for a projection device equipped with, A control unit that switches between diffusion and transmission of light transmitted or reflected through the mask portion that is incident on the polymer-dispersed liquid crystal portion. A program designed to function as such.

Images