JP2014142492A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which can make an area where very glaring bright spots are observed, small.SOLUTION: A display device has a screen 21 which can switch between a transparent state and a scattering state for visible light, and a tabular reflecting plane symmetry imaging element 41 ejecting luminous flux entered with a convergence or emission state for an own element surface with an emission or convergence state for the element surface being symmetrical. An image plane 61 of an image light projected to image with the appointed image plane 61 and the screen 21 are placed in plane symmetry for the reflecting plane symmetry imaging element 41.

Description

  The present invention relates to a display device that displays an image.

  2. Description of the Related Art Conventionally, display devices that display a video by projecting a video projected from a light source such as a projector onto a screen (projection surface) are known.

  For example, Patent Document 1 describes that a display image is projected onto a screen capable of switching between light scattering and transmission states using a spatial light modulator and an enlarged projection optical system. Patent Document 2 describes an image display device that is driven for each divided area of the screen corresponding to the image area based on the depth information of the image. The projection principle is spatial light modulation as in Patent Document 1. And projecting a display image by a magnified projection optical system.

JP 2002-139700 A Japanese Patent Laying-Open No. 2005-024764

  In the case of Patent Document 1, when an observer observes a display image, there is no problem if the projected light is in a completely diffusing state on the screen, but the light diffusing state on the screen is not in a completely diffusing state. When the linearly transmitted light remains, the place where the optical path connecting the observer's viewpoint and the magnifying projection optical system intersects with the screen is observed as a very bright bright spot for the observer. Also in the case of Patent Document 2, when the projected light is not completely diffused on the screen and linearly transmitted light remains, the observer is positioned at a position where the observer's line of sight coincides with the optical axis of the light beam projected from the image projection apparatus. A very bright spot is observed.

  That is, in Patent Documents 1 and 2, since the image light is projected while enlarging the projection area, there is a problem that the area observed as a bright spot that is very bright for the observer becomes large.

  Therefore, in view of the above-described problems, an object of the present invention is to provide a display device that can reduce a region where, for example, very bright luminescent spots are observed.

  In order to solve the above-mentioned problem, the invention described in claim 1 is incident on a screen that can switch between a transmission state and a scattering state for visible light, and a convergent or divergent state with respect to its own element surface. A plate-like reflection-type plane-symmetric imaging element that emits a light beam symmetrically with respect to the element surface in a diverging or converging state, and the imaging of the image light projected so as to form an image on a predetermined imaging plane The display device is characterized in that a plane and the screen are positioned symmetrically with respect to the reflection-type plane-symmetric imaging element.

  According to a third aspect of the present invention, a screen capable of switching between a transmissive state and a scattering state with respect to visible light, and a light beam incident in a convergent or divergent state with respect to its own element surface are symmetrical with respect to the element surface. A plate-like reflection-type plane-symmetric imaging element that emits in a divergent or converged state, and a light diffusing member provided at a focal position of image light composed of projected laser light, the light diffusing member and the The display device is characterized in that a screen is positioned in plane symmetry with respect to the reflection-type plane-symmetric imaging element.

1 is a schematic configuration diagram of a display device according to a first embodiment of the present invention. It is typical sectional drawing of the screen shown by FIG. FIG. 2 is a perspective view of the reflective surface-symmetric imaging element shown in FIG. 1. It is a perspective view which shows the rectangular parallelepiped material which comprises the reflection type plane-symmetric image formation element shown by FIG. It is a perspective view which shows the combination of two sheet | seat parts which form the reflection type plane-symmetric image formation element shown by FIG. FIG. 2 is a perspective view of a micro mirror unit in XYZ orthogonal coordinates for conceptually explaining the micro mirror unit in the reflection-type plane-symmetric imaging element shown in FIG. 1. FIG. 7 is a plan view of a minute mirror unit on an XY plane viewed from the Z-axis direction in the minute mirror unit shown in FIG. 6. FIG. 8 is a side view of the first and second light reflecting surfaces when viewed from a direction perpendicular to the bisector of the angle formed by the first and second light reflecting surfaces of FIG. 7 and the Z axis. FIG. 2 is a plan view of the reflective surface-symmetric imaging element shown in FIG. 1. FIG. 2 is a perspective view of the reflective surface-symmetric imaging element shown in FIG. 1. FIG. 2 is a perspective view of the reflective surface-symmetric imaging element shown in FIG. 1. FIG. 2 is a timing chart of the state of the screen shown in FIG. 1, the linear transmittance of light beams of a light control unit, and the intensity of image light projected from a projector. 2 is a flowchart illustrating an operation of the screen illustrated in FIG. 1. It is a schematic block diagram of the display apparatus concerning the 2nd Example of this invention.

  Hereinafter, a display device according to an embodiment of the present invention will be described. A display device according to an embodiment of the present invention includes a screen capable of switching between a transmission state and a scattering state with respect to visible light, and a light beam incident on the element surface in a convergent or divergent state with respect to the element surface. And a plate-like reflection-type plane-symmetric imaging element that emits light in a divergent or convergent state. Then, the imaging plane of the image light projected so as to form an image on a predetermined imaging plane and the screen are positioned symmetrically with respect to the reflective plane-symmetric imaging element. By doing so, the image light incident in the divergent state of the reflective surface-symmetric imaging element can be emitted in a converged state, and thus projected onto the screen as convergent light. Therefore, it is possible to reduce a region where a very bright luminescent spot or the like is observed.

  In addition, a light diffusing member may be provided on the imaging surface. By doing so, the projection light is further diffused and enters the reflection-type plane-symmetric imaging element. Therefore, at the same time as the viewing angle is expanded, even when a bright spot is observed, the brightness can be reduced as compared with the conventional case.

  A display device according to another embodiment of the present invention includes a screen capable of switching between a transmission state and a scattering state with respect to visible light, and a light beam incident on the element surface in a convergent or divergent state. A plate-like reflection type plane-symmetric imaging element that radiates or converges symmetrically with respect to the element surface, and a light diffusion member provided at the focal position of the image light composed of the projected laser light . The light diffusing member and the screen are positioned in plane symmetry with respect to the reflection type plane symmetric imaging element. In this way, even if the image light is laser light, it can be diverged by the light diffusing member, and the reflection type plane-symmetric imaging element converges and emits the incident image light. Can be projected on the screen as convergent light. Therefore, it is possible to reduce a region where a very bright luminescent spot or the like is observed. In addition, by providing the light diffusing member, the viewing angle is widened, and at the same time, when a bright spot is observed, the brightness can be reduced as compared with the conventional case.

  The reflective surface-symmetric imaging element has two layers of mirror sheets formed by joining a plurality of rectangular parallelepiped mirror members, and the longitudinal direction of the mirror member in the first layer of the two layers You may laminate | stack so that the longitudinal direction of a two-layer mirror member may orthogonally cross. By doing so, the incident light beam is reflected and emitted twice by the first layer and the second layer, so that the light beam incident in the divergent state is converted into convergent light by the two reflections and emitted. Further, since it is sufficient to laminate two layers of rectangular parallelepiped mirror members, the structure is simple and the manufacture is facilitated.

  Moreover, you may have a control means which switches alternately the permeation | transmission state and scattering state of a screen with a predetermined period. By doing in this way, since the display of a screen and the observation of the background over a screen, etc. can be performed alternately, each display and observation can be performed by time division. Therefore, the image displayed on the screen and the background can be observed substantially simultaneously.

  In addition, a light shielding means for blocking light may be installed at a position that is plane-symmetric with the projection port of the image light with respect to the reflective surface-symmetric imaging element. By doing in this way, the light which is going to diverge beyond the convergence point of convergent light can be shielded.

  Also, the image formed on the image plane or the image formed at the focal position and the image projected on the screen are the same size, and the image formed on the image plane or formed at the focal position is projected on the screen. The image has a symmetrical relationship. Therefore, by adjusting the positional relationship between the image formed on the imaging plane or at the focal position and the reflective plane-symmetric imaging element, the image is correctly displayed on the screen as viewed from the user.

  A display device 1 according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the display device 1 includes a projector 11, a screen 21, a synchronization control unit 31, a reflection-type plane-symmetric imaging element 41, and a housing 51. The projector 11, the screen 21, and the synchronization control unit 31 are transmissive projection devices that project (project) the image light (projected image) of the projector 11 and transmit and scatter it on the screen 21 (projection surface).

  The projector 11 is disposed in the housing 51. The projector 11 may be any projector as long as it can project video light modulated by video information onto the screen 21. Note that the video information is obtained from a video signal input to the projector 11. The projector 11 may receive a video signal of a still image as well as a video signal of a moving image. Further, the projector 11 emits a mirror image that is upside down with respect to the image displayed on the screen 21. That is, the image formed on the image forming surface 61 and the image projected on the screen 21 have a plane symmetry relationship.

  The screen 21 is attached to an attachment portion 51 b that protrudes from the upper surface 51 a of the housing 51. The visible state can be switched between a transmissive state and a scattered state, and the background can be observed through the screen 21 in the transmissive state, and the image light projected from the projector 11 in the scattered state. Can be displayed.

  FIG. 2 is a schematic cross-sectional view of the screen 21 that can control the optical state. The screen 21 shown in FIG. 2 has a light control unit 25 that is an optical layer in which a composite material containing liquid crystal is sandwiched between a pair of transparent glass substrates 23 and 24. A counter electrode 26 is formed on the entire surface of one glass substrate 24 on the light control unit 25 side. A control electrode 27 is formed on the entire surface of the other glass substrate 23 on the light control section 25 side. An intermediate layer made of an insulator may be formed between the electrodes 26 and 27 and the light control unit 25.

  The screen 21 includes a light control unit 25 made of an element or a material that can change an optical state by applying a voltage. The optical state of the light control unit 25 is a state in which the scattering state displays an image, and a transparent transmission state in which the scattering of incident light is smaller and the linear transmittance of light is higher than that is a non-image display state in which no image is displayed. It is. The light control unit 25 is disposed between the counter electrode 26 and the control electrode 27. That is, the light control unit 25 is sandwiched between two electrodes and can switch an optical state between a transmission state and a scattering state by a voltage applied between the two electrodes.

  As the light control unit 25, one that can switch an optical state between a scattering state and a transmission state, for example, a so-called polymer dispersed liquid crystal (PDLC) in which nematic liquid crystal domains are distributed in a polymer can be used. In addition, a better optical state can be realized by using a composite material that is associated with the orientation of liquid crystal molecules in which a polymer network forms domains in a state where no voltage is applied.

  As an example using PDLC, a suitable amount of photopolymerizable monomer, nematic liquid crystal and polymerization initiating material are mixed and placed between 5 and 50 micron substrates of glass or resin constituting the light control member. The liquid crystal domain can be dispersed in the polymer by irradiating with ultraviolet rays under conditions such as phase separation temperature. In this case, the normal mode is designed so that the scattering due to the refractive index difference between the polymer and the liquid crystal is large when no voltage is applied, and the refractive index difference in the substrate normal direction is small when the liquid crystal is aligned by an electric field. Called. In addition, it is also possible to use a capsule containing a nematic liquid crystal mixed with a monomer and a polymerization initiator.

  As a composite material associated with the orientation of liquid crystal molecules in which a polymer network forms domains in a state where no voltage is applied, a photopolymerizable monomer has liquid crystal properties. The substrate is subjected to an alignment process such as rubbing, and the mixed material disposed between the substrates has an arrangement based on the alignment process. By irradiating ultraviolet rays in this state, the above initial arrangement is obtained when no voltage is applied, and scattering occurs due to the difference in refractive index between the liquid crystal domain and the polymer when the voltage is applied. In addition, when the unidirectional arrangement is used, it has optical characteristics depending on this orientation. However, it is also possible to use an optical characteristic that does not depend on the polarization of incident light by adding a chiral material and twisting the initial arrangement. . In this case, the scattering due to the difference in refractive index between the polymer and the liquid crystal is small when a normal voltage is not applied, and the refractive index difference is increased when the liquid crystal is aligned by an electric field, which is called a reverse mode.

  That is, in the normal mode, a transmission state is obtained when a predetermined voltage is applied between the electrodes, and a scattering state is obtained when no voltage is applied between the electrodes. In the reverse mode, a scattering state occurs when a predetermined voltage is applied between the electrodes, and a transmission state occurs when no voltage is applied between the electrodes.

  The counter electrode 26 and the control electrode 27 are formed as transparent electrodes using, for example, ITO (indium tin oxide).

  For the user located on the glass substrate 24 side of the screen 21, for example, when the light control unit 25 of the screen 21 is in a scattering state, the screen 21 appears to be clouded. On the other hand, when the light control unit 25 is in the transmissive state, the screen 21 is in the transmissive state, so that the background can be observed through the screen 21. Therefore, when the dimming unit 25 is in the scattering state, the image light projected from the projector 11 can be displayed on the screen 21, and in the transmissive state, the screen 21 has transparency that can recognize the background.

  A voltage is applied to the screen 21 so as to generate a potential difference between the control electrode 27 and the counter electrode 26. As the drive waveform (drive voltage waveform), for example, one electrode may be in a DC state (0 volt), and an AC voltage may be applied to the other electrode, or an AC voltage whose phase is inverted to both electrodes. May be applied to generate a potential difference. That is, when a voltage is applied so as to generate a potential difference between the control electrode 27 and the counter electrode 26, the screen 21 is in a transmission state when in the normal mode, and is in a scattering state when in the reverse mode. In this embodiment, the screen 21 may be in either the normal mode or the reverse mode.

  The synchronization control unit 31 serving as a control unit is disposed in the housing 51. The synchronization control unit 31 controls the dimming unit 25 of the screen 21 on which the image light is projected to a state in which the image light is scattered when the image light is projected, and enters a transmission state when the image light is not projected. Control. That is, a voltage is applied so that the light control unit 25 is in a scattering state or a transmission state. The synchronization control unit 31 is connected to the projector 11 and the screen 21 as shown in FIG. The synchronization control unit 31 controls the optical state of the screen 21 (the light control unit 25) in synchronization with the projection of the image light from the projector 11. Further, as the synchronization signal input from the projector 11 to the synchronization control unit 31, for example, a synchronization signal synchronized with the video frame period of the video signal input to the projector 11 can be used.

  The synchronization control unit 31 may include a CPU (Central Processing Unit), a memory, and the like, and may be configured by a computer whose operation is controlled by a program, or a dedicated control configured by an ASIC (Application Specific Integrated Circuit) or the like. It may be hardware.

  The reflection-type plane-symmetric imaging element 41 has a flat plate shape and is disposed on the upper surface 51a of the housing 51 so as to be orthogonal to the screen 21 (in parallel with the upper surface 51a). That is, the reflective surface-symmetric imaging element 41 has one surface exposed from the housing 51 and the other surface accommodated in the housing 51. The reflection-type plane-symmetric imaging element 41 receives the image light projected from the projector 11 and exits toward the screen 21.

  An example of the reflection-type plane-symmetric imaging element 41 is, for example, as shown in FIG. Sheet portions (mirror sheets) 43 and 44 are provided. The sheet portions 43 and 44 have their main surfaces bonded together.

  As shown in FIG. 4, two opposing surfaces among the four surfaces extending in the longitudinal direction of the rectangular parallelepiped material 45 are light transmission surfaces T used for light transmission. One of the remaining two surfaces is a reflecting surface and is subjected to a mirror surface treatment. This mirror surface treatment does not mean that light is reflected, but is a treatment that makes a very smooth state. The other of the remaining two surfaces is a surface that absorbs light. About 100 to 20000 rectangular parallelepiped materials 45 are used in each of the sheet portions 43 and 44. For example, the rectangular parallelepiped material 45 is made of a plastic or glass rod typified by transparent acrylic having a side of a rectangular cross section in a direction perpendicular to the longitudinal direction, that is, a lateral direction of 0.1 to 10 mm. The length varies depending on the size of the projected image, but is about 100 mm to 10 m. A light reflecting film 46 is formed on one surface of the rectangular parallelepiped material 45 extending in the longitudinal direction (the surface opposite to the remaining one surface). The light reflecting film 46 is formed by vapor deposition or sputtering of aluminum or silver. A light absorbing film 47 is formed on the surface opposite to the surface on which the light reflecting film 46 is formed (the remaining one surface), thereby forming a light absorbing surface. The light absorption film 47 may be formed by using a matte black paint or the like, or by adhering a thin black sheet.

  For such a plurality of rectangular parallelepiped members 45, as shown in FIG. 5, sheet portions 43 and 44 are formed by bringing the light-absorbing film surface of one rectangular parallelepiped member 45 into close contact with the light reflecting film surface of another rectangular parallelepiped member 45, respectively. Is done. As shown in FIG. 5, the sheet portions 43 and 44 are bonded together in a state in which one of the rectangular parallelepiped materials 45 is rotated by 90 degrees so that the parallel directions of the rectangular parallelepiped materials 45 intersect each other. Is formed. That is, two layers of mirror sheets are laminated so that the longitudinal direction of the mirror member of the first layer of the two layers and the longitudinal direction of the mirror member of the second layer are perpendicular to each other. The portion where each rectangular parallelepiped material 45 of the sheet portion 43 and each rectangular parallelepiped material 45 of the sheet portion 44 intersect constitutes a micromirror unit, and the light reflecting film surface of the sheet portion 43 of each micromirror unit is the first aggregate. 1 light reflecting surface, and the light reflecting film surface of the sheet portion 44 is the second light reflecting surface of the second aggregate.

  When the sheet portions 43 and 44 are formed, the light absorption film surface of one rectangular parallelepiped material 45 and the light reflection film surface of another rectangular parallelepiped material 45 are brought into close contact with each other. Alternatively, they may be laminated.

  Furthermore, since the rectangular parallelepiped material 45 is made of plastic resin, glass, or the like, it has a refractive index of about 1.5, which may cause surface reflection. Therefore, a dereflection coating may be applied to both the front and back surfaces of the reflective surface-symmetric imaging element 41.

  Next, the operation principle of the reflection-type plane-symmetric imaging element 41 shown in FIGS. 3 to 5 will be described. Since the reflection-type plane-symmetric imaging element 41 is composed of a large number of micromirror units as described above, only one micromirror unit will be described.

  FIG. 6 is a perspective view of the minute mirror unit Mu in XYZ orthogonal coordinates for conceptually explaining the minute mirror unit. The minute mirror unit Mu includes a first light reflecting surface Mxz and a second light reflecting surface Myz that are orthogonal to the element surface (XY plane).

  In the micromirror unit Mu, if there is a certain point (black circle) in the unit cell (1, 1, 1,), the black circle (1, -1,1,) is on the mirror surface of the first light reflecting surface Mxz. Black circles (-1, 1, 1,) are respectively projected onto the image space on the mirror surface of the second light reflecting surface Myz. Here, −1 in the XYZ orthogonal coordinate values means the reverse direction of each axis direction, and means that the plane is inverted to a plane perpendicular to each axis direction.

  Since the mirror surface of the first light reflection surface Mxz and the mirror surface of the second light reflection surface Myz in the image space have XYZ orthogonal coordinates, the black circle (1, -1,1,) and the black circle (-1,1,1) )) Is projected on the space of the diagonal position of the real space of the unit cell (1,1,1,) with the star (-1, -1, -1,).

  Therefore, the relationship between the star (-1, 1, 1, 1) in the diagonal position space and the black circle (1, 1, 1,) in the real space is the XY axis direction of the black circle (1, 1, 1,). Is in a relationship reversed with the position of the asterisk (-1, -1, 1,) in the XY-axis direction.

  FIG. 7 is a plan view of the minute mirror unit Mu on the XY plane viewed from the Z-axis direction. Here, the real space is (1, 1, 1,), the image space by the mirror surface of the first light reflecting surface Mxz is (1, -1, 1,), and the image space by the mirror surface of the second light reflecting surface Myz. (−1, 1, 1,) and the mirror image space of the image space of the first and second light reflecting surfaces Mxz, Myz is represented as (−1, −1, 1,). Assuming that the line B is in the real space (1, 1, 1,), a virtual image Bv that is inverted in the XY-axis direction is obtained in the image space (-1, -1, 1,). When a light beam is incident on the mirror surface of the second light reflecting surface Myz in the real space (1, 1, 1,) at an angle θ, the light beam is reflected and reflected by the mirror surface of the first light reflecting surface Mxz at an angle φ, and the second light. The light is returned in the same direction in parallel with the incident light beam on the mirror surface of the reflecting surface Myz.

  Therefore, the incident light beam to the micro mirror unit Mu other than the normal direction of each of the first light reflection surface Mxz and the second light reflection surface Myz is the first and second light reflection surfaces Mxz, which open from the Z axis of the XY plane. It returns in the same direction as a light beam reversed within the range of Myz (less than 90 degrees), that is, recursively. By the way, if you prepare two mirrors, align them at right angles and look vertically at the intersection of the mirrors, you can observe that your face is always in the middle at any position in the horizontal direction. Sex is obvious.

  However, in the Z-axis direction, the recursiveness due to the first and second light reflecting surfaces Mxz and Myz of the micromirror unit Mu does not appear. FIG. 8 is a side view of the first and second light reflecting surfaces Mxz and Myz viewed from a direction perpendicular to the bisector of the angle formed by the first and second light reflecting surfaces Mxz and Myz in FIG. 7 and the Z axis. is there. Here, when a light beam is incident on the mirror surface of the second light reflecting surface Myz in the real space (1, 1, 1,) at an angle ψ with respect to the Z axis, the light beam is reflected and reflected by the mirror surface of the first light reflecting surface Mxz. , Reflected at an angle ψ with respect to the Z axis. Incidentally, in order to obtain complete recursion, if a third light reflecting surface is further provided on the XY plane of FIG. 6, recursion by the white circle image space (-1, -1, -1,) of FIG. Can be obtained. This is known as the retroreflectivity of a corner cube or retroreflector in which incident light beams directed to three intersecting lines return to the same incident direction at any incident position when these three mirrors orthogonal to each other are combined.

  In the reflection-type plane-symmetric imaging element 41, a plurality of micro mirror units Mu that regularly reflect incident light rays in the Z-axis direction component and retroreflect incident light rays in the XY-axis direction component are shown in FIG. As shown in the figure, for example, the first light reflection surface Mxz and the second light reflection surface Myz are arranged in a matrix in a plane so as to coincide with each other in the XY axis direction. Needless to say, the reflection-type plane-symmetric imaging element 41 is configured to allow light to pass in the Z-axis direction (at least partially reflected twice).

  As shown in FIG. 10, for example, if there is a light emitter that emits divergent light CvB on the positive side (upper side) on the Z-axis of the reflective plane-symmetric imaging element 41, the micromirror unit of the reflective plane-symmetric imaging element 41 is effective. Of all the light rays spread in the region, each of the light rays reflected twice by each of the first and second light reflecting surfaces Mxz and Myz is in a plane-symmetric position with respect to the reflective surface-symmetric imaging element 41 of the light emitter. Converge.

  On the other hand, as shown in FIG. 11, for example, convergent light DvB is incident on the micromirror unit effective region of the reflective surface-symmetric imaging element 41 from the positive side (upper side) on the Z-axis of the reflective surface-symmetric imaging element 41. For example, the light beam reflected twice by each of the first and second light reflecting surfaces Mxz and Myz in the light condensing region therein diverges in a plane symmetry from the reflective surface-symmetric imaging element 41 and spreads as diverging light. .

  That is, the reflective surface-symmetric imaging element 41 emits a light beam incident on the element surface in a convergent or divergent state in a divergent or convergent state symmetrically with respect to the element surface.

  In the display device 1, an image formation surface 61 (see FIG. 1) of the projector 11 is formed between the projector 11 and the reflection-type plane-symmetric image formation element 41. The imaging surface 61 and the screen 21 are positioned symmetrically with respect to the reflection-type plane-symmetric imaging element 41. Therefore, the projector 11 is adjusted in the installation position, the focal position, and the like so that the imaging plane 61 is positioned at a position that is plane-symmetric with the screen 21 with respect to the reflective plane-symmetric imaging element. The imaging surface 61 has the same size as the image projected on the screen 21 through the reflective plane-symmetric imaging element 41.

  FIG. 12 is a timing chart showing the state of the screen 21 configured as described above, the linear transmittance of the light beam of the light control unit 25, and the intensity (light intensity) of the image light projected from the projector 11.

  As shown in FIG. 12, the screen 21 changes between a scattering state and a transmission state once within one video period. That is, the transmission state and the scattering state are alternately switched at a predetermined cycle. One video cycle is one frame period of the video signal input to the projector 11 and is, for example, about 50 to 60 Hz. Therefore, the screen 21 is switched between the scattering state and the transmission state in a period shorter than one video cycle.

  When the screen 21 (the light control unit 25) is in a scattering state, the linear transmittance of the light beam of the light control unit 25 is lowered. Since light incident on the screen during this period is scattered, an image can be displayed. Accordingly, since the projector 11 projects the image light onto the screen 21, the image light intensity increases and an image is displayed.

  When the screen 21 is in the transmission state, the linear transmittance of the light beam of the light control unit 25 increases. Light incident on the screen during this period is transmitted as it is. Accordingly, the projector 11 stops projecting the image light on the screen 21. Therefore, the background can be observed through the screen 21 (through the screen 21).

  On the screen 21, the image of the entire screen is repeatedly projected every one image period, and this repetition is not recognized as blinking by the human eye, but is projected onto the screen 21 by time averaging (integration). The image and the background can be observed simultaneously without feeling flicker.

  The operations described above are summarized in the flowchart of FIG. The flowchart shown in FIG. 13 is executed by the synchronization control unit 31.

  First, in step S1, a synchronization signal for detecting the head of one video cycle is detected, and the process proceeds to step S2. The synchronization signal may be a synchronization signal synchronized with the video frame period of the video signal input to the projector 11 described above. In addition, the projector 11 is set to the state which is not projecting image light as an initial state.

  Next, in step S2, a voltage is applied to the counter electrode 26 and the control electrode 27 so that the screen 21 is in a scattering state, and the process proceeds to step S3.

  Next, in step S3, image light is projected on the projector 11, and the process proceeds to step S4. That is, the projector 11 outputs projection control information for projecting an image input from the outside as image light. The projection control information may be a control signal system in which the start and stop of projection are defined at a high level and a low level of one signal line, and is composed of a combination of a high level and a low level of a plurality of signal lines. A command format in which start and stop of projection are defined in the command or the like may be used. Further, this step is performed after the transient state shown in FIG. 12 has elapsed. The period of the transient state can be calculated in advance by the material constituting the light control unit 25 and the applied voltage.

  Next, in step S4, the projection of the video performed in step S3 is stopped after the elapse of a predetermined period, and the process proceeds to step S5. The projection period of this image is determined according to the period of the scattering state of the screen 21. That is, the projector 11 outputs projection control information for stopping the projection of the image light to the projector 11.

  Next, in step S5, a voltage is applied to the counter electrode 26 and the control electrode 27 so that the screen 21 is in a transmissive state, and the process proceeds to step S6.

  Next, in step S6, it is determined whether or not the use of the display device 1 is to be ended. If it is to be ended (in the case of YES), the flowchart is ended, and if it is not to be ended (in the case of NO), the process returns to step S1. Whether or not to end may be determined by, for example, whether or not the user has performed an input operation.

  As described above, in the display device 1 configured as described above, the image light projected from the projector 11 is incident on the reflection-type plane-symmetric imaging element 41 as divergent light. The image light that has entered the reflection-type plane-symmetric imaging element 41 becomes focused light by the reflection-type plane-symmetric imaging element 41 and is emitted toward the screen 21. Then, the image light emitted from the reflective plane-symmetric imaging element 41 is projected on the screen 21 in a scattered state, and an image is displayed.

  Here, even if the light diffusion state on the screen 21 is not a complete diffusion state and the linearly transmitted light remains, the image light transmitted through the screen 21 becomes convergent light that converges at the point X in FIG. When the observer has a possibility of observing a very bright luminescent spot, the range of the triangle formed by the screen 21 and the X point (the shaded portion in FIG. 1) is projected directly from the projector 11. In other words, the image light becomes narrower as compared with the case of projecting while expanding the projection area.

  According to the present embodiment, the screen 21 capable of switching between a transmission state and a scattering state with respect to visible light, and a light beam incident on the element surface in a convergent or divergent state diverges or converges symmetrically with respect to the element surface. A plate-like reflection type plane-symmetric imaging element 41 that emits in a state. Since the imaging surface 61 of the image light projected so as to form an image on the predetermined imaging surface 61 and the screen 21 are arranged in plane symmetry with respect to the reflective surface-symmetric imaging element 41, the reflective type Since the image light incident on the plane-symmetric imaging element 41 in a divergent state can be emitted in a convergent state, it is projected onto the screen 21 as convergent light. Therefore, it is possible to reduce a region where a very bright luminescent spot or the like is observed.

  The reflection-type plane-symmetric imaging element 41 includes two layers of mirror sheet portions 43 and 44 formed by joining a plurality of rectangular parallelepiped materials 45, and the longitudinal direction of the rectangular parallelepiped material 45 of the sheet portion 43 and the sheet portion are stacked. 44 are stacked so that the longitudinal direction of the rectangular parallelepiped material 45 is orthogonal, the incident light flux is reflected and emitted twice in the first and second layers. Is converted into convergent light by the reflection of the light and emitted. Moreover, since it is sufficient to laminate two layers of the rectangular parallelepiped material 45, the structure is simple and the manufacture becomes easy.

  Further, since the synchronization control unit 31 alternately switches between the transmission state and the scattering state of the screen 21 at a predetermined cycle, the display on the screen 21 and the observation of the background over the screen 21 can be performed alternately. Each display and observation can be performed in a time-sharing manner. Therefore, the image displayed on the screen 21 and the background can be observed substantially simultaneously.

  Further, the image formed on the image formation surface 61 and the image projected on the screen 21 have the same size, and the image formed on the image formation surface 61 and the image projected on the screen 21 are vertically inverted. Therefore, even when the reflection type plane symmetric imaging element 41 is used, the positional relationship between the image formed on the imaging plane or the image formed at the focal position and the reflection type plane symmetric imaging element 41 is adjusted. Thus, the video is correctly displayed on the screen 21 as viewed from the user.

  Next, a measuring apparatus according to a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the projector 11 is a laser projector. The laser projector includes, for example, a scanning mechanism including a laser light source of three colors of red, blue, and green, an optical unit that combines the laser light of each light source, a mirror and an actuator that scan the combined laser light, and the like. Direct drawing is performed by scanning laser light emitted to a screen or the like installed at a focal position (also called a laser scanning method or a direct drawing method).

  In the present embodiment, a microlens array 71 as a light diffusing member is disposed at the position (focal position of the image light) that is the image plane 61 in the first embodiment. As is well known, the microlens array 71 is formed by uniformly forming a minute convex lens (or concave lens) of about 1 mm or less on a flat plate serving as a substrate without a gap, and can diffuse incident light. That is, the microlens array 71 and the screen 21 are positioned symmetrically with respect to the reflection type plane-symmetric imaging element 41.

  Since the projector 11 of the present embodiment is a laser projector, an image cannot be formed on the image plane 61 as in the first embodiment. Therefore, by arranging the microlens array 71 at the position of the imaging surface 61, an image is formed at that position, and the formed image becomes diffused light (diverged light) and enters the reflective surface-symmetric imaging element 41. Can be made. That is, the projector 11 is adjusted so that the position of the microlens array 71 becomes the focal position of the image light.

  According to the present embodiment, the screen 21 capable of switching between a transmission state and a scattering state with respect to visible light, and a light beam incident on the element surface in a convergent or divergent state diverges symmetrically with respect to the element surface. It has a plate-like reflection-type plane-symmetric imaging element 41 that emits in a converged state, and a microlens array 71 that is provided at the focal position of image light made up of projected laser light. Since the microlens array 71 and the screen 21 are positioned symmetrically with respect to the reflective plane-symmetric imaging element 41, even if the image light is laser light, the reflective plane-symmetric imaging element 41 is Since the image light incident in the divergent state can be emitted in a converged state, it is projected on the screen 21 as converged light. Therefore, it is possible to reduce a region where a very bright luminescent spot or the like is observed.

  In addition, by arranging the microlens array 71, the video light is further diffused and enters the reflective surface-symmetric imaging element 41, so that the viewing angle is enlarged and a bright spot is observed at the same time. In addition, the brightness can be reduced as compared with the prior art.

  The microlens array 71 is not limited to the second embodiment described above, and may be used in the first embodiment. In that case, since the degree of diffusion of the image formed on the imaging surface 61 is increased, the viewing angle is increased, and at the same time, when a bright spot is observed, the brightness is reduced as compared with the conventional case. The effect that it can be obtained.

  Further, since the image light is radiated after being converged at the point X in FIGS. 1 and 14, a light shielding means such as a light shielding plate for shielding the light may be provided at the position of the point X. This light shielding means may be integrated with the casing 51 so as to be connected to the upper portion of the screen 21, or may be installed at a point X as a separate body from the casing 51. Note that the point X is in a plane-symmetrical position with respect to the projection opening of the projector 11 with respect to the reflection-type plane-symmetric imaging element 41, and therefore can be easily obtained from the position of the projector 11. That is, a light-shielding means for blocking light may be installed at a position that is plane-symmetric with respect to the image light exit port with respect to the reflective surface-symmetric imaging element 41.

  Further, the present invention is not limited to the above embodiment. That is, those skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the scope of the present invention. Of course, such modifications are included in the scope of the present invention as long as the configuration of the display device of the present invention is provided.

DESCRIPTION OF SYMBOLS 1 Display apparatus 21 Screen 31 Synchronization control part (control means)
41 Reflective surface-symmetric imaging element 43 Sheet part (mirror sheet)
44 Seat (mirror sheet)
45 Cuboid material (mirror member)
61 Imaging surface 71 Micro lens array (light diffusion member)

Claims (7)

A screen capable of switching between a transmission state and a scattering state for visible light;
A plate-like reflection-type plane-symmetric imaging element that emits a light beam incident on the element surface in a convergent or divergent state symmetrically with respect to the element surface;
A display device characterized in that the imaging plane of the image light projected so as to form an image on a predetermined imaging plane and the screen are positioned symmetrically with respect to the reflective plane-symmetric imaging element. .   The display device according to claim 1, wherein a light diffusion member is provided on the imaging surface. A screen capable of switching between a transmission state and a scattering state for visible light;
A plate-like reflection-type plane-symmetric imaging element that emits a light beam incident on the element surface in a convergent or divergent state symmetrically with respect to the element surface;
A light diffusing member provided at the focal position of the image light composed of the projected laser light,
The display device, wherein the light diffusing member and the screen are positioned symmetrically with respect to the reflective surface-symmetric imaging element.   The reflection-type plane-symmetric imaging element is formed by laminating two layers of mirror sheets formed by joining a plurality of rectangular parallelepiped mirror members, and the longitudinal direction of the mirror member of the first layer of the two layers and the second 4. The display device according to claim 1, wherein the layers are stacked so that a longitudinal direction of the mirror member is orthogonal to each other. 5.   5. The display device according to claim 1, further comprising a control unit that alternately switches the transmission state and the scattering state of the screen at a predetermined cycle.   6. A display device according to claim 1, wherein a light shielding means for blocking light is installed at a position which is plane-symmetric with respect to the image light exit port with respect to the reflection type plane-symmetric imaging element.   The image formed on the imaging plane or formed at the focal position and the image projected on the screen have the same size, and the image formed on the imaging plane or formed at the focal position and the screen The display device according to claim 1, wherein an image projected on the screen has a plane-symmetrical relationship.

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