JP2008191279A - Image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain speckles, while suppressing an occurrence of blur of a projection image in an image forming apparatus that projects images by using coherent light, such as a laser beam. <P>SOLUTION: The image display apparatus includes a light source that emits a coherent light; an intermediate image forming section for forming an intermediate image by using light from the light source; an imaging optical system for imaging light from the intermediate image onto a display screen; and a diffusion changing section, having a diffusing face at a certain location shifted from an intermediate image forming face, on which the intermediate image is formed, and on an optical path, extending to the imaging optical system from the intermediate forming section that includes the intermediate image forming section, and serves to make diffusion within a face along the diffusing face change temporally. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display device that projects an image on a display surface, and more particularly to an image display device that projects an image using coherent light such as laser light.

  In a projector (projection display device) that is an image display device that projects an image, it has been proposed to use laser light in order to improve color reproducibility, brightness, contrast, and the like of a projected image. However, in a projector using laser light, there is a problem in that a flickering flicker called “speckle” occurs in a projected image due to coherence of the laser light.

  As a method for solving this problem, for example, as in the example described in Patent Document 1, an intermediate image is formed and the formed intermediate image is projected, and a diffusion plate is disposed at the intermediate image formation position. It is disclosed that speckles are suppressed by reciprocating (vibrating) the arranged diffusion plate in the direction along the diffusion surface or rotating the diffusion plate within the diffusion surface.

JP 2006-53495 A

  However, when the diffusion plate arranged at the intermediate image forming position is vibrated or rotated as described above, the position of the diffusion surface may be shifted in a direction perpendicular to the intermediate image forming surface. As a result, the projected image may be blurred.

  The present invention has been made to solve the above-described problems, and suppresses occurrence of blurring of a projected image in an image display apparatus that projects an image using coherent light such as laser light. However, it aims at providing the technique which can suppress a speckle.

In order to solve at least a part of the above problems, an image display device of the present invention includes:
An image display device that projects an image on a display surface,
A light source that emits coherent light;
An intermediate image forming unit that forms an intermediate image using light from the light source;
An imaging optical system for forming light from the intermediate image on the display surface;
A diffusing surface at a position shifted from the intermediate image forming surface on which the intermediate image is formed, at any position on the light path from the intermediate image forming unit to the imaging optical system, including the inside of the intermediate image forming unit A diffusivity variation part that temporally changes the diffusivity in a plane along the diffusion surface;
It is characterized by providing.

  In the above image display device, by changing the diffusivity of the diffusing surface at a position shifted from the intermediate image forming surface over time, the occurrence of blurring of the projected image, which has been a problem in the prior art, is suppressed, and speckles are generated. Can be suppressed.

In the above image display device,
The diffusivity variation part is
A diffusion element constituting the diffusion surface;
A diffusion surface swinging portion that swings the diffusion element in a direction along the diffusion surface;
It is realizable by providing.

  Here, the oscillating movement of the diffusing element by the diffusing surface oscillating portion may be realized by oscillating the diffusing plate along any one of the directions in the plane along the diffusing surface. Good. Alternatively, the oscillating movement of the diffusing element by the diffusing surface oscillating portion may be realized by rotating the diffusing element in a plane along the diffusing surface.

  In any case, the diffusivity of the diffusing surface can be easily changed over time.

  Note that a random phase plate having random phase characteristics in a plane along the diffusion surface can be applied to the diffusion element constituting the diffusion surface. Further, a diffusing element using an antiglare film may be applied.

In the above image display device,
The diffusivity variation part is
The phase control surface corresponding to the diffusion surface and divided into a plurality of regions along the diffusion surface, and according to the drive voltage applied to the electrodes of each region, the light emitted from each region A phase control device for controlling the phase characteristics;
A phase control device drive unit that applies the drive voltage to the electrodes in each region,
The phase control device driver is
For each of the regions, a randomly changing voltage is applied as the driving voltage, and the phase characteristics are changed randomly for each of the regions, thereby along the diffusion surface as the phase control surface. This can also be realized by changing the in-plane diffusivity with time.

  Here, the phase control device can be realized by applying a liquid crystal device or a transparent piezoelectric device.

In any of the above image display devices,
The intermediate image forming unit emits light representing the image by modulating light from the light source according to the image; and
An intermediate image forming optical system that forms light from the light modulation device as the intermediate image on the intermediate image forming surface;
The light path from the intermediate image forming unit to the imaging optical system may be a light path from the light modulation device to the imaging optical system.

Or
The intermediate image forming unit includes a scanning device that scans light representing the image based on light from the light source,
The light path from the intermediate image forming unit to the imaging optical system may be a light path from the scanning device to the imaging optical system.

  In addition, the intermediate image forming unit including the scanning device may further include an intermediate image forming optical system that forms light from the scanning device as the intermediate image on the intermediate image forming surface. .

  In any case, the intermediate image forming unit can be easily configured.

  The intermediate image forming optical system is preferably a telecentric optical system.

  If the intermediate image forming optical system is a telecentric optical system, the light utilization efficiency can be improved.

In any of the above image display devices,
The diffusing surface is preferably disposed at a position near the outside of the focal depth of the imaging optical system with the intermediate image forming surface as a center.

In addition, in an image display apparatus including an intermediate image forming optical system that is a telecentric optical system,
It is also preferable that the diffusing surface is disposed at a pupil position in the intermediate image forming optical system.

  As described above, the speckle can be more effectively suppressed by disposing the diffusion surface at a position near the outside of the focal depth of the imaging optical system or at the pupil position of the imaging optical system. .

In any of the above image display devices,
The diffusion surface as a second diffusion surface;
It is also preferable to provide a diffusing element constituting the first diffusing surface at the position of the intermediate image forming surface.

  As described above, it is possible to more effectively suppress speckle by providing the diffusion element constituting the first diffusion surface at the position of the intermediate image forming surface.

  The diffusivity of the second diffusion surface can be made smaller than that of the first diffusion surface.

  Moreover, it is preferable that the diffusion particle size of the diffusion element constituting the first diffusion surface is smaller than the pixel size of the intermediate image.

  In this way, it is possible to effectively diffuse the light emitted from the intermediate image formed on the intermediate image forming surface.

  Moreover, it is preferable that the diffusing element constituting the first diffusing surface is constituted by a diffusing element capable of setting the angle of spread of the emitted light within a desired angle range.

  In this way, the balance between the reduction in the loss of light emitted from the imaging optical system and the reduction in the intensity of the light emitted from the imaging optical system, the conditions of the usable imaging optical system, etc. The considered configuration is easy.

  The diffusion element capable of setting the angle of spread of the emitted light to a desired angle range is a diffusion element using a hologram, and the uneven pitch of the hologram is smaller than the size of the pixel of the intermediate image. preferable.

  This effectively diffuses the light emitted from the intermediate image formed on the intermediate image forming surface, reduces the loss of light emitted from the imaging optical system, and emits the light from the imaging optical system. The configuration in consideration of the balance with the reduction of the intensity of the emitted light, the conditions of the usable imaging optical system, and the like becomes easy.

  Although the aspect described above has shown the aspect of the image display apparatus that projects an image on the display surface, the present invention is not limited to this, and various aspects such as the aspect of the display optical system for configuring the image display apparatus are included. This embodiment can also be realized.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
D. Variation:

A. First embodiment:
FIG. 1 is an explanatory diagram showing a schematic configuration of a projector 10A as a first embodiment of the present invention. The projector 10A includes liquid crystal light valves 120R, 120G, and 120B for red (R), green (G), and blue (B), laser light illuminators 110R, 110G, and 110B for each color, and a cross dichroic prism 130. Two projection optical systems 140 and 150 and two diffusion elements 160 and 170 are provided. Each component is arranged such that the planes including the respective central axes (shown by dotted lines in the figure) are parallel to each other. In the drawing, for simplification, only the optical elements related to the description of the present invention are shown among the constituent elements of the projector 10A, and other elements are omitted.

  Each color laser light illumination device 110R, 110G, 110B has a function of irradiating a corresponding color liquid crystal light valve 120R, 120G, 120B with a corresponding color laser light as illumination light.

  The red laser light illumination device 110R includes a red laser light source device 111R that emits the red laser light LBr, an integrator optical system 112R that equalizes the illuminance distribution of the red laser light LBr emitted from the red laser light source device 111R, A field lens 113R for making the red laser light LBr emitted from the integrator optical system 112R incident so that its principal ray is perpendicular to the light incident surface (surface perpendicular to the central axis) of the red liquid crystal light valve 120R; It is equipped with. Similarly, the green laser light illumination device 110G includes a green laser light source device 111G, an integrator optical system 112G, and a field lens 113G, and the blue laser light illumination device 110B includes a blue laser light source device 111B, an integrator optical system 112B, and a field lens 113B. It has.

  Each color laser light source device 111R, 111G, and 111B includes a semiconductor laser and a wavelength conversion element that emits only laser light of a corresponding color wavelength. Note that the wavelength conversion element is not an essential component, but a component that is appropriately provided according to the output wavelength of the semiconductor laser. Further, since the output of the laser diode constituting the semiconductor laser is small by itself, normally, a laser diode array in which a plurality of laser diodes are arranged in an array is used as the semiconductor laser.

  The red liquid crystal light valve 120R modulates the red laser light LBr emitted from the red laser light illumination device 110R according to image information of each color of the image to be displayed, and forms an image for forming an optical image representing the image of each color. It has a function of emitting light. The same applies to the green liquid crystal light valve 120G and the blue liquid crystal light valve 120B. That is, the liquid crystal light valves 120R, 120G, and 120B for the respective colors correspond to the light modulation device of the present invention.

  The cross dichroic prism 130 has a function as a color light combining optical system that combines the image light of each color emitted from the liquid crystal light valves 120R, 120G, and 120B of each color, and the combined image light is the first projection optical. Guide to system 140.

  The first projection optical system (also referred to as “projection lens”) 140 has a function of forming an intermediate image by forming image light emitted from the cross dichroic prism 130. The first projection optical system 140 corresponds to the intermediate image forming optical system of the present invention.

  The second projection optical system 150 has a function of forming image light emitted from the intermediate image formed on the intermediate image forming surface IPS on the screen SC. The second projection optical system 150 corresponds to the imaging optical system of the present invention.

  The liquid crystal light valves 120R, 120G and 120B, which are light modulation devices, the cross dichroic prism 130, and the first projection optical system 140 correspond to the intermediate image forming unit of the present invention in this embodiment.

  The two diffusing elements 160 and 170 are constituted by a transmissive diffusing plate, for example.

  FIG. 2 is an explanatory diagram showing the arrangement of the two diffusion elements 160 and 170. 2A is a plan view showing the arrangement of the two diffusing elements 160 and 170 along the light traveling direction, and FIG. 2B is a front view seen from the second projection optical system 150 side. .

  As shown in FIG. 2A, the first diffusing element 160 is fixedly arranged so that the diffusing surface 162 coincides with the intermediate image forming surface IPS. The position that coincides with the intermediate image forming surface IPS includes a position in the vicinity of the intermediate image forming surface IPS, that is, a position that is within the focal depth of the first projection optical system 140 with the intermediate image forming surface IPS as a reference. It is.

  Further, the second diffusing element 170 is disposed at a position where the diffusing surface 172 is shifted to the first projection optical system 140 side from the intermediate image forming surface IPS. More specifically, a position outside the focal depth with reference to the intermediate image forming surface IPS corresponding to the focal position on the object point side of the second projection optical system 150 and as close as possible to the first diffusing element 160 side. Further, the diffusion surface 172 is arranged so as to face the diffusion surface 162 of the first diffusion element 160.

  As shown in FIG. 2A, the second diffusing element 170 is connected to the rotation shaft 182 of the rotation drive unit 180. As shown in FIG. 2B, the rotation drive unit 180 is connected to the rotation shaft 182. Is rotated, the diffusion surface 172 of the second diffusion element 170 is rotated within the diffusion surface. By this rotation, the position in the diffusion surface 172 through which the image light emitted from the first projection optical system 140 passes changes, and the diffusibility of the image light passing through the second diffusion element 170 changes with time. Will continue. As a result, the speckle pattern generated in the projected image on the screen SC changes from moment to moment, so that the speckle is smoothed and uniformed over time, resulting in the coherence of the laser light. It is possible to reduce speckle generated. However, it is preferable to set the rotation speed of the second diffusing element 170 to be higher than the response speed of the human eye in order to smooth and uniform the speckle pattern that changes every moment. The rotation driving unit 180 corresponds to the diffusion surface swinging unit of the present invention in this embodiment, and the second diffusion element 170 and the rotation driving unit 180 correspond to the diffusivity changing unit of the present invention in this embodiment.

  Here, as described above, the diffusing surface 172 of the second diffusing element 170 is disposed outside the focal depth of the second projection optical system 150. For this reason, even if an intermediate image is formed on the diffusion surface 172 of the second diffusing element 170, the intermediate image is not formed on the screen SC. There is a low possibility that

  As described above, the projector 10A of the present embodiment is emitted from the intermediate image on the intermediate image forming surface IPS by the first diffusing element 160 in which the diffusing surface 162 is arranged so as to coincide with the intermediate image forming surface IPS. The range of the angle of light (diffusion angle) is expanded and the diffusion surface 172 of the second diffusion element 170 is rotated within the diffusion surface, thereby changing the diffusivity of the light passing through the diffusion surface 172 every moment. Therefore, speckles generated in the projected image can be effectively reduced. Further, the arrangement position of the second diffusing element 170 is shifted from the intermediate image forming surface IPS, and even if the second diffusing element 170 is rotated, the occurrence of blurring of the projected image, which is a problem in the conventional example, is generated. Can be suppressed.

  By the way, since the image light emitted from the second projection optical system 150 uses laser light as a light source, it is desirable that the intensity is within an intensity range that is visible to humans. For this reason, it is preferable to increase the diffusibility so that the image light emitted from the second projection optical system 150 falls within a desired intensity range. On the other hand, the brightness of the projected image is generally desirable to be bright.

  For this reason, the first diffusing element 160 increases the diffusivity (diffusion angle) as much as possible so that the intensity of the image light emitted from the second projection optical system 150 is within a desired intensity range, while projecting. In order to minimize the loss of image light for forming an image, the second projection optical system 150 is a projection optical system having a large penetration angle, that is, a projection optical system having a small F number and a large aperture diameter. It is preferable to use a system. However, if the diffusivity is too large, it becomes difficult to manufacture the projection optical system, which is expensive. Therefore, the diffusibility of the first diffusing element 160 is reduced in the loss of image light emitted from the second projection optical system 150 to form a projection image on the screen SC, and the second projection optical system. It is preferable to make it as large as possible in consideration of the balance of the contradictory relationship with the reduction in the intensity of the image light emitted from 150, the F number of the available projection optical system, the lens aperture, and the like.

  In addition, in a general diffusion plate, it is difficult to set the range of the angle of light emitted (diffusion angle) with respect to the angle of incident light to a desired range. For example, it is preferable to use a diffusion element using a hologram or a diffraction grating. If such a diffusing element is used, the range of the diffusion angle of the emitted light can be set to a desired range, and the loss of image light emitted from the second projection optical system 150 can be reduced. It is possible to realize a configuration that takes into consideration various conditions such as the balance between the reduction of the intensity of the image light emitted from the second projection optical system 150 and the F number and aperture of the available projection optical system.

  In addition, the diffusion plate used as the first diffusion element 160 is such that the size of the diffusion particles, holograms, and diffraction gratings constituting the diffusion surface 162 is the size of the pixels of the intermediate image formed on the intermediate image forming surface IPS. It is preferable that it is smaller than this. In this way, it is possible to effectively diffuse the light emitted from each pixel of the intermediate image.

  On the other hand, the purpose of the second diffusing element 170 is to temporally change the diffusivity of the diffusing surface through which the image light emitted from the first projection optical system 140 passes and to change the generated speckle pattern temporally. Since they are superimposed and uniform, the diffusivity on the diffusing surface 172 of the second diffusing element 170 may change with time, and the magnitude thereof is smaller than that of the first diffusing element 160. Good. Conversely, if the diffusibility of the first diffusing element 160 is made larger, there is a possibility of causing light loss. Therefore, the second diffusing element 170 may have any diffusivity smaller than that of the first diffusing element 160. For example, a diffuser plate or a random phase plate using an antiglare film can be used.

  The first diffusing element 160 may be omitted. However, in order to reduce speckles more effectively and suppress the occurrence of blurring of the projected image, which has been a problem in the prior art, and In order to keep the image light emitted from the second projection optical system 150 within a desired intensity range, it is desirable not to omit the first diffusion element 160.

  The projection magnification of the first projection optical system 140 is preferably set to 2 times or less in consideration of downsizing of the apparatus, and is preferably made smaller than the projection magnification of the second projection optical system 150. In addition, the F number of the first projection optical system 140 is larger and smaller than the F number of the second projection optical system 150 in consideration of the reduction in the number of constituent lenses and the reduction in manufacturing cost. Is preferred.

  In the projector 10A of the above embodiment, the liquid crystal light valve using a transmissive liquid crystal device as the light modulation device has been described as an example. However, a liquid crystal light valve using a reflective liquid crystal device or a digital micromirror device ( Various light modulation devices such as “DMD” (trademark of Texas Instruments) can be used.

  In addition, the projector 10A of the above embodiment is configured to rotate the second diffusing element 170 in the diffusing surface, but is not limited to this, and includes, for example, a diffusing surface vibrating portion, and in the diffusing surface. A configuration in which the diffusion surface swinging portion is provided, such as a configuration in which the second diffusion element is swung in any direction, may be configured to swing the second diffusion element in a direction along the diffusion surface. However, in the vibration, when the vibration direction is switched, a period in which the diffusibility change temporarily stops occurs. Therefore, rotation is more advantageous for speckle reduction.

  In the projector 10 </ b> A of the above embodiment, the second diffusing element 170 is disposed outside the focal depth of the second projection optical system 150 and in the vicinity of the incident side of the first diffusing element 160. However, the present invention is not limited to this, and the first liquid crystal light valves 120R, 120G, and 120B of the respective colors that are out of the focal depth of the second projection optical system 150 and are light modulation devices are used for the first. It may be arranged at any position on the light path to the diffusing element 160. Further, it is not limited to the incident side of the first diffusing element 160, and any one of the light paths outside the focal depth of the second projection optical system 150 and to the second projection optical system 150. It may be arranged at a position. However, the effect of reducing speckles is higher when arranged as close to the first diffusion element 160 as possible. Further, the second diffusing element 170 may be disposed at the position of the pupil in the first projection lens 140.

B. Second embodiment:
FIG. 3 is an explanatory diagram showing a schematic configuration of a projector 10B as a second embodiment of the invention. The projector 10B includes a diffusivity changing unit including the second diffusing element 170 and the rotation driving unit 180 of the projector 10A (FIG. 1) of the first embodiment, and the operations of the phase control device 210 and the phase control device 210. The configuration is the same as that of the projector 10A of the first embodiment, except that the diffusivity changing unit configured by the phase control device driving unit 220 to be controlled is replaced. Therefore, hereinafter, the phase control device 210 and the phase control device driving unit 220 having different configurations will be described.

  FIG. 4 is an explanatory diagram showing the phase control surface 212 of the phase control device 210 in an enlarged manner. In the phase control device 210, a phase control surface 212 corresponding to a diffusion surface is divided into a plurality of regions along the surface direction. The example in the figure shows an example in which the phase control surface 212 is divided into matrix regions A11 to A68 of 6 rows and 8 columns. However, the number of the divided regions is an example for facilitating the illustration and description, and is not limited to this. Control voltages V11 to V68 generated in the phase control device driving unit 220 are applied to electrodes (not shown) in the regions A11 to A68, respectively. Each region A11 to A68 can control the phase of light passing therethrough according to the magnitude of the applied control voltages V11 to V68. For example, a liquid crystal device or a transparent piezoelectric device can be used as such a phase control device.

  Here, by changing the values of the control voltages V11 to V68 applied to the respective regions A11 to A68 randomly and temporally, the phase characteristics of the respective regions can be randomly changed temporally. As a result, It is possible to temporally change the diffusibility of light emitted from the phase control surface 212 as a diffusion surface. Thereby, the same effect as the case where the second diffusing element described in the first embodiment is swung in the direction along the diffusing surface can be obtained. As a result, speckles generated in the projected image are generated by changing the diffusivity of the image light (indicated by cross hatching in the figure) emitted from the first projection optical system 140 passing through the phase control device 210 every moment. Can be effectively reduced. Moreover, since the phase control device 210 and the first diffusing element 160 are fixed, there is no occurrence of blurring of the projected image, which is a problem in the conventional example.

  Also in this embodiment, the restrictions on the diffusibility on the first and second diffusing surfaces and the restrictions on the first and second projection optical systems described in the first embodiment are similarly applied.

C. Third embodiment:
FIG. 5 is an explanatory diagram showing a schematic configuration of a projector 10C as a third embodiment of the present invention. This projector 10C is crossed with laser light illumination devices 110R, 110G, 110B and liquid crystal light valves 120R, 120G, 120B corresponding to the R, G, B colors of the projector 10A (FIG. 1) of the first embodiment. The dichroic prism 130 is replaced with a laser light source device 110RC, 110GC, 110BC corresponding to each color of R, G, B, and a two-dimensional scanner 230, and the other first projection optical system 140, The configurations of the second diffusing element 170, the first diffusing element 160, and the second projection optical system 150 are the same. The second projection optical system 150 is not shown.

  In the projector 10C, the substantially parallel laser beams emitted from the laser light source devices 110RC, 110GC, and 110BC corresponding to the respective colors R, G, and B are two-dimensionally scanned in a horizontal direction and a vertical direction by a two-dimensional scanner 230. Each of the laser beams scanned at high speed and scanned in the two-dimensional direction is combined by the first projection optical system 140 on the intermediate image forming surface IPS corresponding to the diffusion surface 162 of the first diffusion element 160. And an intermediate image is formed on the intermediate image forming surface IPS. That is, the projector 10C according to the present embodiment is a projector having a configuration using a scanning type intermediate image forming unit.

  Note that a modulation circuit 250 is connected to the laser light source devices 110RC, 110GC, and 110BC for each color of R, G, and B, and this modulation circuit 250 is configured for each color according to image information supplied from a control circuit (not shown). The intensity of laser light emitted from the laser light source devices 110RC, 110GC, and 110BC is modulated. Thereby, the intermediate image formed on the intermediate image forming surface IPS becomes an image according to the image information.

  The two-dimensional scanner 230 is controlled by a control circuit 240 that controls the scanning direction of the two-dimensional scanner.

  Note that the two-dimensional scanner 230 can be realized by using, for example, a MEMS (Micro Electro Mechanical System) mirror device that can vibrate one mirror in a two-dimensional direction. It is also possible to combine two one-dimensional MEMS mirror devices.

  In the projector having the configuration using the scanning type intermediate image forming unit such as the projector 10C of the present embodiment, the spec generated in the projected image while suppressing the blur of the projected image, similarly to the projector 10A of the first embodiment. Can be effectively reduced.

  The projector 10C according to the present embodiment includes laser light illumination devices 110R, 110G, and 110B and liquid crystal light valves 120R, 120G, and 120B that correspond to the R, G, and B colors of the projector 10A according to the first embodiment. The configuration in which the cross dichroic prism 130 is replaced with the laser light source devices 110RC, 110GC, and 110BC corresponding to the R, G, and B colors and the two-dimensional scanner 230 has been described as an example, but the R of the projector 10B of the second embodiment is described. , G, B corresponding to each color, the laser light illumination devices 110R, 110G, 110B, the liquid crystal light valves 120R, 120G, 120B, and the cross dichroic prism 130 are replaced with laser light source devices 110RC corresponding to the respective colors R, G, B. 110GC, 110BC, and the two-dimensional scanner 230 It is also possible to replace trees.

  Further, the projector 10C of the present embodiment has been described by way of an example of a projector using a scanning intermediate image forming unit by a two-dimensional scanner, but an optical modulation device having a column of pixels arranged in a direction perpendicular to the scanning direction It is also possible to use a scanning-type intermediate image forming unit using a one-dimensional scanner.

  Also in this embodiment, the restrictions on the diffusibility on the first and second diffusing surfaces described in the first embodiment and the restrictions on the first and second projection optical systems are similarly applied. However, among the restrictions on the arrangement position of the second diffusing element, the restriction on the arrangement on the incident side of the first diffusing element 160 is outside the focal depth of the second projection optical system 150 and is two-dimensional. It is limited to any position in the light path from the scanner 230 to the first diffusing element 160.

D. Variation:
In addition, this invention is not restricted to said Example and embodiment, In the range which does not deviate from the summary, it is possible to implement in various forms.

  For example, in the above embodiment, the first diffusing element 160 has been described as an example of a transmissive diffusing element that widens the angle of light passing therethrough. However, a configuration using a reflective diffusing element that widens the angle of reflected light is used. Also good.

  In the above-described embodiment, the case where laser light is used as coherent light has been described as an example. However, the present invention is not limited to this, and coherent light such as light emitted from an LED is used. In this case, the present invention can be applied.

It is explanatory drawing which shows schematic structure of 10 A of projectors as 1st Example of this invention. It is explanatory drawing shown about arrangement | positioning of the two diffusion elements 160 and 170. FIG. It is explanatory drawing which shows schematic structure of the projector 10B as 2nd Example of this invention. FIG. 3 is an explanatory diagram showing an enlarged phase control surface 212 of the phase control device 210. It is explanatory drawing which shows schematic structure of the projector 10C as 3rd Example of this invention.

Explanation of symbols

10A, 10B, 10C ... Projectors 110R, 110G, 110B ... Laser light illumination devices 110RC, 110GC, 110BC ... Laser light source devices 112R, 112G, 112B ... Integrator optical systems 113R, 113G. 113B ... Field lenses 120R, 120G, 120B ... Liquid crystal light valve 130 ... Cross dichroic prism 140 ... First projection optical system 150 ... Second projection optical system 160 ... First diffusion element 162 ... Diffusion surface 170 ... Second Diffusion element 172 ... Diffusion surface 180 ... Rotation drive unit 182 ... Rotating shaft 210 ... Phase control device 212 ... Phase control surface 220 ... Control circuit 240 ... Control circuit 250 ... Modulation circuit SC ... Screen IPS ... Intermediate image forming surface

Claims (19)

An image display device that projects an image on a display surface,
A light source that emits coherent light;
An intermediate image forming unit that forms an intermediate image using light from the light source;
An imaging optical system for forming light from the intermediate image on the display surface;
A diffusing surface at a position shifted from the intermediate image forming surface on which the intermediate image is formed, at any position on the light path from the intermediate image forming unit to the imaging optical system, including the inside of the intermediate image forming unit A diffusivity variation part that temporally changes the diffusivity in a plane along the diffusion surface;
An image display device comprising: The image display device according to claim 1,
The diffusivity variation part is
A diffusion element constituting the diffusion surface;
A diffusion surface swinging portion that swings the diffusion element in a direction along the diffusion surface;
An image display device comprising: The image display device according to claim 2,
The image display characterized in that the oscillating of the diffusing element by the diffusing surface oscillating portion is realized by oscillating the diffusing plate along one of the directions in a plane along the diffusing surface. apparatus. The image display device according to claim 2,
The image display apparatus according to claim 1, wherein the oscillating motion of the diffusing element by the diffusing surface oscillating portion is realized by rotating the diffusing element in a plane along the diffusing surface. The image display device according to any one of claims 2 to 4,
The image display device, wherein the diffusion element is a random phase plate having random phase characteristics in a plane along the diffusion surface. The image display device according to any one of claims 2 to 4,
The image display device, wherein the diffusion element is a diffusion element using an antiglare film. The image display device according to claim 1,
The diffusivity variation part is
The phase control surface corresponding to the diffusion surface and divided into a plurality of regions along the diffusion surface, and according to the drive voltage applied to the electrodes of each region, the light emitted from each region A phase control device for controlling the phase characteristics;
A phase control device drive unit that applies the drive voltage to the electrodes in each region,
The phase control device driver is
For each of the regions, a randomly changing voltage is applied as the driving voltage, and the phase characteristics are changed randomly for each of the regions, thereby along the diffusion surface as the phase control surface. An image display device characterized by temporally changing in-plane diffusivity. The image display device according to claim 7,
The image display apparatus according to claim 1, wherein the phase control device is a liquid crystal device or a transparent piezoelectric device. The image display device according to any one of claims 1 to 8,
The intermediate image forming unit emits light representing the image by modulating light from the light source according to the image; and
An intermediate image forming optical system that forms light from the light modulation device as the intermediate image on the intermediate image forming surface;
The light path from the intermediate image forming unit to the imaging optical system is a light path from the light modulation device to the imaging optical system. The image display device according to any one of claims 1 to 8,
The intermediate image forming unit includes a scanning device that scans light representing the image based on light from the light source,
The light path from the intermediate image forming unit to the imaging optical system is a light path from the scanning device to the imaging optical system. The image display device according to claim 10,
The intermediate image forming unit further includes an intermediate image forming optical system that forms light from the scanning device as the intermediate image on the intermediate image forming surface. The image display device according to claim 9 or 11,
The image display apparatus according to claim 1, wherein the intermediate image forming optical system is a telecentric optical system. An image display device according to any one of claims 1 to 12,
The image display apparatus according to claim 1, wherein the diffusion surface is disposed at a position near the outside of a focal depth of the imaging optical system with the intermediate image forming surface as a center. The image display device according to claim 12,
The image display apparatus, wherein the diffusion surface is disposed at a position of a pupil in the intermediate image imaging optical system. The image display device according to any one of claims 1 to 14,
The diffusion surface as a second diffusion surface;
An image display device comprising a diffusion element constituting a first diffusion surface at a position of the intermediate image forming surface. The image display device according to claim 15,
An image display device characterized in that the diffusivity of the second diffusing surface is smaller than that of the first diffusing surface. The image display device according to claim 15 or 16, wherein
An image display device, wherein a diffusion particle size of a diffusion element constituting the first diffusion surface is smaller than a pixel size of the intermediate image. The image display device according to claim 15 or 16, wherein
The image display device, wherein the diffusing element constituting the first diffusing surface is constituted by a diffusing element capable of setting a spread angle of emitted light within a desired angle range. The image display device according to claim 18,
The diffusion element capable of setting the angle of spread of the emitted light to a desired angle range is a diffusion element using a hologram, and the uneven pitch of the hologram is smaller than the size of the pixel of the intermediate image. An image display device.

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