Projection display device and projection display system

A projection display device D includes an acquiring means 2 that acquires a pixel value Cg and a depth value Cz for each of a plurality of pixels constituting an image, a light output means 3 that outputs pixel display light Ld per pixel according to the pixel value, a light guide body 5 that guides the pixel display light Ld to a position corresponding to the pixel on a projection surface 8, and changes the light path length of the pixel display light Ld to the projection surface 8 according to the depth value Cz of the pixel. The light guide body 5 includes a reflector 51 that has mirror surfaces 511a opposing each other. The light path length control means 3 changes the number of times the pixel display light is reflected by the mirror surfaces 511a of the reflector 51 according to the depth value Cz of the pixel.

TECHNICAL FIELD

The present invention relates to a technique for viewing an image stereoscopically.

BACKGROUND ART

Various methods have heretofore been proposed for allowing a viewer to view an image stereoscopically. For example, Patent Document 1 discloses a method for displaying a synthesized image composed of right-eye and left-eye images with parallax on a display device, and allowing the viewer's right-eye to see only the right-eye image and the viewer's left-eye to see only the left-eye image. According to this method, the viewer is able to perceive a sense of depth that depends on the amount of parallax between the right-eye and left-eye images (hereinafter, “horizontal parallax”).

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

However, with this type of technique it is necessary to restrict the horizontal parallax to within a specific range. If the horizontal parallax is too great, the viewer of the image may suffer eyestrain or have a queasy feeling like seasickness, or the viewer may be unable to perceive a sense of three-dimensionality as a result of the left-eye and right-eye images being perceived separately. More specifically, the horizontal parallax at which the viewer can perceive a sense of three-dimensionality on the screen of a display device is at the very most around 8 mm (around 6.5 cm if a projector is used to project an enlarged image onto a screen). Consequently, the viewer cannot be made to perceive a sense of depth corresponding to a horizontal parallax that exceeds this limit. For example, if an image whose sense of three-dimensionality can be perceived is to be displayed by a display device that has three to four pixels arranged in areas 1 mm in length, the number of gradations of the sense of three-dimensionality (number of depth gradations that the user perceives) will be restricted to between 24 and 32 gradations, since the smallest unit of horizontal parallax is one pixel of a display device. Thus, a problem with methods for allowing a viewer to see an image with horizontal parallax is that the viewer cannot be made to perceive an adequate sense of depth. An object of the present invention, which was arrived at in view of the above situation, is to provide a mechanism that is able to allow a viewer to perceive an image rich with a sense of depth.

Means for Solving the Problem

To solve the above problem, a projection display device according to the present invention includes an acquiring means for acquiring a pixel value and a depth value for each of a plurality of pixels constituting an image, a light output means for outputting light per pixel according to the pixel value, a light guide body for guiding the light output per pixel from the light output means to a position corresponding to the pixel on a projection surface, and a control means for changing a light path length of the light output per pixel from the light output means to the projection surface according to the depth value of the pixel. Based on a configuration in which the depth values are determined so that the depth perceived by the viewer (user) increases the larger the depth value, for example, the light length control means controls the light path length from the light output means to the projection surface so that the light path length increases the larger the depth value. According to this configuration, a viewer of an image projected onto the projection surface is able to perceive a sense of depth that depends on the depth values, since the light path length of light output from the light output means to the projection surface is adjusted per pixel according to the depth values. Moreover, in this configuration, horizontal parallax of an image as in conventional technology is unnecessary in principle. Consequently, the viewer can be made to perceive an image having a sufficient sense of depth without being restricted to horizontal parallax.

Also, a projection display device according to the present invention includes an acquiring means for acquiring a pixel value and a depth value for each of a plurality of pixels constituting an image, a light output means for outputting light per pixel according to the pixel value, a reflector having light reflecting surfaces that oppose each other, and for guiding the light output per pixel from the light output means to a position corresponding to the pixel on a projection surface by reflecting the light with the light reflecting surfaces, and a control means for changing the number of times the light output per pixel from the light output means is reflected by the light reflecting surfaces of the reflector according to the depth value of the pixel. Based on a configuration in which the depth values are determined so that the depth perceived by the viewer increases the larger the depth value, for example, the control means controls the reflected number of times in the reflector so that the reflected number of times increases the larger the depth value. According to this configuration, the sense of depth perceived by the viewer increases the greater the reflected number of times of light output from the light output means to the projection surface. Moreover, in this configuration, horizontal parallax of the image as in conventional technology is unnecessary in principle, since the viewer perceives a depth that depends on the reflected number of times in the reflector. Consequently, the viewer can be made to perceive an image having a sufficient sense of depth without being restricted to horizontal parallax.

A configuration for controlling the reflected number of times in the reflector can be adopted in which the position and angle at which light output from the light output means is incident on the reflector is changed. A configuration is conceivable in which the orientation (particularly the angle) of the light output means is changed according to the depth values. However, it is highly probably that a large and complicated configuration will be required to change this angle because the light output means is often composed of various elements such as a light source and a device for modulating the light output from the light source according to the pixel values. Accordingly, in a preferred mode of the present invention, a reflecting member is provided for guiding the light output from the light output means to the reflector by reflecting the light, and the control means drives the reflecting member so that the angle at which the light reflected by the reflecting member is incident on the light reflecting surfaces of the reflector depends on the depth value. In this mode, the angle at which light output from the light output means and reflected by the reflecting member is incident on the reflector is changed by the control means, with the light reaching the projection surface after being reflected by the reflector for a number of times that depends on this angle of incidence. According to this configuration, a reflecting member with light reflectivity need only be driven, making it possible to simplify and miniaturize the configuration in comparison to when the orientation of the light control means is controlled. A configuration in which the orientation of the light control means is controlled, or a configuration that combines this configuration and the configuration for driving the reflecting member can, however, also be adopted in the present invention.

A mode for reflecting the light output from the light output means with a reflecting member can be adopted in which a member supported so that an angle relative to the direction of the light output from the light output means is changeable is used as a reflecting member, and the control means controls the angle of the reflecting member according to the depth value. A known micro mirror device is adopted as this reflecting member, for example. Further, in another mode, the reflecting member is supported so as to be rotatable on a rotary shaft and has a reflecting surface whose angle relative to the direction of the light output from the light output means changes in a circumferential direction of the rotary shaft, and the control means rotates the reflecting member to an angle that depends on the depth value.

Incidentally, in the present invention, light corresponding to the pixels is irradiated onto areas partitioning the projection surface (hereinafter, “unit areas”). In this configuration, because the cross-sectional area of the light flux (hereinafter, “light flux cross-sectional area”) output from the light output means decreases the greater the reflected number of times in the reflector, the light flux cross-sectional area of light reaching the projection surface may be smaller than the unit area (seeFIG. 7(b)). An area of the unit area not irradiated with light occurs around the area irradiated with light flux in this case, which is likely to invite a drop in display quality. Accordingly, in a preferred mode of the present invention, the control means drives the reflecting member so that an angle at which light reflected by the reflecting member is incident on the light reflecting surfaces of the reflector depends on the depth value, and makes the reflecting member oscillate in the driven state. Because light flux irradiated onto a unit area can be made to move minutely within the unit area according to this configuration by making the reflecting member oscillate (using light flux to paint out the entire unit area, if you like), it appears to the viewer as though the light is being irradiated onto the entire unit area, even when reflected a large number of times in the reflector. Consequently, even if the light is reflected a plethora of times, a drop in display quality caused by this is suppressed.

Alternatively, a configuration can also be adopted in which the light flux cross-sectional area of light output from the light output means is adjusted in advance to be larger the greater the reflected number of times (i.e., the larger the depth value), since the cross-sectional area of light flux on the projection surface becomes smaller the greater the reflected number of times. That is, in this mode, a light flux adjustment means is provided for changing the light flux cross-sectional area of light output from the light output means according to the depth value. Based on a configuration in which the control means changes the reflected number of times in the reflector so that the reflected number of times increases the larger the depth value, for example, the light flux adjustment means changes the light flux cross-sectional area of light output from the light output means so that the light flux cross-sectional area increases the larger the depth value. Even if the light flux cross-sectional area is reduced following the reflection in the reflector, a drop in display quality caused by this is suppressed according to this configuration because the light flux that reaches the projection surface can be made to extend over the entire unit area according to this mode.

Also, the light path length from the projection display device to the projection surface differs depending on the position of the pixel. Consequently, even if the reflected number of times in the reflector is changed according to the depth value, the light path length from the light output means to the projection surface may possibly depart from the light path length that depends on the depth value due to this difference in light path lengths. Accordingly, in a preferred mode of the present invention, a correction means is provided for correcting the depth value of each pixel according to the position corresponding to the pixel on the projection surface, and the control means controls the number of times that light output from the light output means is reflected by the light reflecting surfaces of the reflector according to the depth value after correction by the correction means. For example, the correction means corrects the depth value so that when the same depth value is given to one pixel and another pixel, the light path length of light output from the light output means to the projection surface is substantially the same for the one pixel and the other pixel. According to this mode, display of an image is realized in which depth values are accurately reflected because the depth values are corrected according to the projected position on the projection surface.

The present invention is also specified as a projection display system that uses the projection display device described above. That is, this system includes a screen that has a projection surface and a projection display device for projecting an image onto the screen. The projection display device includes an acquiring means for acquiring a pixel value and a depth value for each of a plurality of pixels constituting an image, a light output means for outputting light per pixel according to the pixel value, a light guide body for guiding the light output per pixel from the light output means to a position corresponding to the pixel on the projection surface, and a control means for changing a light path length of the light output per pixel from the light output means to the projection surface according to the depth value of the pixel. According to this configuration, similar effects are obtained to the projection display device of the present invention.

Note that the projection surface of the screen preferably is composed of a first reflecting surface for reflecting the light output from the projection display device, and a second reflecting surface for reflecting the light reflected by the first reflecting surface on a viewing side, the first and second reflecting surfaces respectively being arranged in sheets. According to this configuration, the light output from the projection display device can be reliably output on the viewing side. In particular, the reflection of the viewer on the projection surface (i.e., the viewer is aware of his or her own figure on the projection surface) is avoided if the first reflecting surface is substantially horizontal, and the second reflecting surface forms a prescribed angle with the first reflecting surface (e.g., 45 degrees). Further, if the second reflecting surface is divided into a plurality of unit portions, each of which is a curved surface whose center protrudes more than a periphery thereof, light reflected by the second reflecting surface can be output over a wide area, this being particularly suitable in the case where a large number of viewers view images on a large-scale screen. If the second reflecting surface is substantially planar, the manufacturing process can be simplified and manufacturing costs reduced in comparison to when the unit portions of this reflecting surface are curved. Also, display unevenness of an image that depends on the position on the projection surface is suppressed if the first reflecting surface is divided into a plurality of unit portions whose angle relative to a horizontal surface is selected for each unit portion according to an angle at which light output from the projection display device reaches the unit portion.

Effects of the Invention

According to the present invention, the viewer can be made to perceive an image that is rich with a sense of depth.

DESCRIPTION OF REFERENCE NUMERALS

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described here with reference to the drawings. Note that for convenience of description, the dimensions and proportions of the constituent elements in the drawings shown below have been altered accordingly from those of the actual elements.

A. First Embodiment

FIG. 1is a block diagram showing the configuration of a projection display system DS according to a first embodiment of the present invention. As shown in this figure, the projection display system DS includes a projection display device D and a screen S having a projection surface8. Note that inFIG. 1the solid arrow shows the path taken by light, while the broken arrows show the path taken by electronic signals (data).

The projection display device D is for projecting a color image (hereinafter, “display image”) composed of a plurality of colors onto the projection surface8of the screen S, and includes a storage means1, an acquiring means2, a light output means3, a light path length control means4, and a light guide body5. The storage means1stores a pixel value Cg and a depth value Cz for each pixel constituting the display image. Various types of devices can be adopted as the storage means1, including, for example, a hard disk device that incorporates a magnetic disk, a device for driving a portable recording medium typified by a CD-ROM, or a semiconductor memory such as a RAM.

The pixel values Cg are numeric values showing the content for display by each pixel. The gradation values of the colors red, green and blue, for example, are specified as pixel values Cg. The depth values Cz (Z values) are numeric values showing for each pixel a depth that a viewer U should perceive, and are determined so that the depth perceived by the viewer U increases (i.e., the viewer U perceives things as being positioned further back) the larger the depth value Cz. In other words, the numeric values determined as the depth values Cz decrease the smaller the depth perceived by the viewer U. The gradation values of the pixels when representing the image using gray scales, or numeric values calculated by performing various corrections on these gradation values are used as the depth values Cz. In the present embodiment, a case is assumed in which the display image is constituted by pixels arrayed in m number of horizontal rows and n number of vertical columns, as shown inFIG. 2(m and n are both positive integers). For this reason, the pixel values Cg and the depth values Cz are stored in the storage means1for each of “m×n” total number of pixels. The acquiring means2reads the pixel values Cg and the depth values Cz of the pixels sequentially per pixel from the storage means1, and outputs the pixel values Cg to the light output means3and the depth values Cz to the light path length control means4.

The light output means3outputs light per pixel according to the pixel values Cg input from the acquiring means2. As shown inFIG. 1, the light output means3includes a light source31and a lens32. The light source31outputs light (hereinafter, “pixel display light”) Ld per pixel whose wavelength components corresponding to the colors red, green and blue have light intensities that are specified by the pixel values Cg. More specifically, the light source31has light emitting diodes corresponding to the colors red, green and blue, and controls the light emission intensity of the light emitting diodes corresponding to these colors according to the gradation values specified by the pixel values Cg for each color. The lens32is a convex lens (condenser lens) for converting the pixel display light Ld output from the light source31to substantially parallel light. Based on this configuration, the light output means3outputs pixel display light Ld corresponding to each of the plurality of pixels in order at predetermined time intervals (hereinafter, “unit intervals”). In the present embodiment, pixels targeted for output of pixel display light Ld are switched at unit intervals from left to right per row, and targeted rows are switched from top to bottom, as shown by the arrows inFIG. 2. That is, pixel display light Ld corresponding to the pixel in the first row of the first column is output from the start to the end of the first unit interval, and pixel display light Ld corresponding to the pixel in the first row of the second column is output from the start to the end of the second unit interval, as shown inFIG. 3. Once pixel display light Ld for each of the n number of pixels belonging to the first row has been output, pixel display light Ld for each of the pixels in the second row from the first column to the nth column is then output sequentially, after which this outputting operation is repeated for the entire image (one frame). If the display image is a moving image composed of a plurality of still images arranged on a time axis, this series of operations is repeated for the entire display image.

As shown inFIG. 1, the pixel display light Ld output from the light output means3is incident on the light guide body5via the light path length control means4. This light guide body5is for guiding the pixel display light Ld output per pixel from the light output means3to a position corresponding to the pixel on the projection surface8of the screen S. Unit areas Au corresponding to each of the pixels constituting the display image are demarcated on the projection surface8of the screen S. That is, unit areas Au are demarcated over the m horizontal rows and n vertical columns on the projection surface8so as to correspond to the array of pixels in the display image. The pixel display light Ld corresponding to the pixel in the ith row (i being a positive integer satisfying 1≦i≦m) of the jth column (I being positive integer satisfying 1≦j≦n) is guided by the light guide body5to the unit area Au at the ith row of the ith column on the projection surface8.

As shown inFIG. 1, the light guide body5has a reflector51and an output reflecting member58. The reflector51is configured with a pair of opposing reflecting members511that are disposed at a distance from each other so that their respective plate surfaces are substantially parallel. Mirror surfaces511aare formed on the opposing plate surfaces of the reflecting members511. The mirror surfaces511amirror-reflect (total reflection) light reaching the surface thereof. Based on this configuration, incident pixel display light Ld from the light path length control means4is output from the reflector51after being repeatedly reflected alternately by the mirror surfaces511a. The output reflecting member58is for reflecting the pixel display light Ld output from the reflector51onto the projection surface8of the screen S, and has a mirror surface581that mirror-reflects the pixel display light Ld reaching the surface thereof. As described above, the pixel display light Ld reflected by the output reflecting member58is irradiated onto the corresponding unit area Au of the projection surface8.

The light path length control means4is for changing the light path length of the pixel display light Ld output from the light output means3to the projection surface8according to the depth value Cz of the pixel. If, as in the present embodiment, the numeric values determined as the depth values Cz increase the greater the depth that should be perceived by the viewer U, the light path length control means4changes the light path length of the pixel display light Ld so that the light path length increases the larger the depth value Cz input from the acquiring means2. Elaborating further, the light path length control means4changes the number of times (hereinafter, “reflected number of times”) the pixel display light Ld output per pixel from the light output means3is reflected by the mirror surfaces511aof the reflector51according to the depth value Cz of the pixel. Here, because the positional relation of the mirror surfaces511ais fixed, the reflected number of times differs according to the angle or position at which the pixel display light Ld is incident on the reflector51. The light path length control means4of the present embodiment changes the angle at which the pixel display light Ld is incident on the reflector51according to the depth value Cz. More specifically, the light path length control means4changes the angle of incidence of the pixel display light Ld on the reflector51, so that the reflected number of times increases the larger the depth value Cz input from the acquiring means2(so that the reflected number of times decreases the smaller the depth value Cz).

FIG. 4is a block diagram showing a specific configuration of the light path length control means4. As shown inFIGS. 1 and 4, the light path length control means4has an adjustment reflecting member41and a control means45. The adjustment reflecting member41is a substantially rectangular plate member for guiding the pixel display light Ld output from the light output means3to the reflector51by reflecting the pixel display light Ld, and has a mirror surface411that mirror-reflects the pixel display light Ld that reaches the surface thereof. This adjustment reflecting member41is supported by the casing (not shown) of the projection display device D via a fulcrum412, and can be turned in the X direction and the Y direction (directions at right angles to each other) on the fulcrum412. Further, a metal plate413composed of a magnetic body is set up on the opposite side of the adjustment reflecting member41to the fulcrum412.

The control means45is for controlling the orientation of the adjustment reflecting member41according to the depth value Cz input from the acquiring means2, and has an instruction means451and a plurality of magnetic field generators452, as shown inFIG. 4. The magnetic field generators452generate a magnetic field under the control of the instruction means451, and include coils for generating a magnetic field whose strength depends on an applied voltage. The instruction means451causes the magnetic field generators452to generate a magnetic field whose strength depends on the depth value Cz input from the acquiring means2by supplying the magnetic field generators452with a voltage that depends on the depth value Cz. A magnetic force works on the metal plate413of the adjustment reflecting member41as a result of the magnetic field generated in this way, and as a result the adjustment reflecting member41is driven so that the angle of the adjustment reflecting member41relative to a horizontal surface Ls is an angle θ that depends on the depth value Cz.

To execute the drive, the instruction means451refers to a table TBL held in a storage means (not shown). In the table TBL, as shown inFIG. 5, the positions of pixels are associated with the contents of the drive on the adjustment reflecting member41(hereinafter, referred to as “drive content”) and amplitudes Am (Am1, Am2, . . . ) for when the adjustment reflecting member41is oscillated, for every depth value Cz (Cz1, Cz2, . . . ) that can be input from the acquiring means2. Since the adjustment reflecting member41is driven using a magnetic field generated by the magnetic field generators452in the present embodiment, the voltages that should be supplied to the magnetic field generators452are specified as the drive contents of the table TBL. The content of the table TBL is predetermined so that the pixel display light Ld per pixel reaches the unit area Au corresponding to the pixel on the projection surface8, and the number of times the pixel display light Ld is reflected in the reflector51depends on the depth value Cz. The instruction means451firstly retrieves the depth value Cz input from the acquiring means2from the table TBL, and reads the drive content corresponding to the pixel targeted by the retrieved depth value Cz from the drive content associated with this depth value Cz. Here, the instruction means451increments the count of a counter (not shown) whenever the depth value Cz of each pixel constituting a single display image is input, and identifies the position of the pixel based on this count. Alternatively, a configuration is possible in which the acquiring means2notifies the position of the pixel together with the depth value Cz to the instruction means451. The instruction means451then drives the adjustment reflecting member41by supplying the voltage specified in the read drive content to the magnetic field generators452. As a result, the angle θ of the adjustment reflecting member41changes at unit intervals according to the depth values Cz in synch with the output of pixel display light Ld. Note that minute changes in the angle θ of the adjustment reflecting member41at unit intervals as well as the amplitudes Am associated with the depth values Cz in the table TBL are described in a later section.

The configuration of the screen S is described next.FIG. 6is a plan view showing the configuration of the screen S seen from the front of the projection surface8. A cross-section seen from the line I-I inFIG. 6equates to the cross-section of the screen S illustrated inFIG. 1. As shown inFIGS. 1 and 6, the screen S includes the projection surface8for reflecting pixel display light Ld output from the projection display device D on the viewing side (i.e., the side on which the viewer U is situated). This projection surface8is a plane composed of a first mirror surface81and a second mirror surface82disposed alternately in the vertical direction. As shown inFIG. 1, pixel display light Ld output from the projection display device D is output on the viewing side as a result of being reflected firstly by the first mirror surface81and then by the second mirror surface82. The first mirror surface81is a plane that extends in a horizontal direction substantially parallel with a horizontal surface, while the second mirror surface82is a plane that extends horizontally at a prescribed angle α with the first mirror surface81. Consequently, the projection surface8can also be seen as a plane composed of a large number of narrow grooves that equate to the intersection of the first mirror surface81and the second mirror surface82forming an angle α with the first mirror surface81. In the present embodiment, the angle α formed by the first mirror surface81and the second mirror surface82is assumed to be approximately 45 degrees. According to this configuration, the viewer U will not be aware of a reflected image of him or herself on the projection surface8. Note that the dimensions of the first mirror surface81and the second mirror surface82are selected without regard for the arrangement of the pixels constituting the display image (or the arrangement of the unit areas Au). For example, a pitch P of the first mirror surface81and the second mirror surface82shown inFIG. 1does not necessarily match the pitch of the unit areas Au (i.e., distance between the edge of one unit area Au and the corresponding edge of an adjacent unit area Au).

In the configuration described above, as shown inFIG. 1, the pixel display light Ld output per pixel from the light output means3is incident on the reflector51at an angle that depends on the depth value Cz as a result of passing through the light path length control means4, and is mirror-reflected repeatedly by the mirror surfaces511aof the reflector51a number of times depending on the depth value Cz. This pixel display light Ld reaches the projection surface8after being reflected by the output reflecting member58, before then being mirror-reflected sequentially by the first mirror surface81and the second mirror surface82to reach the viewer U. Consequently, the viewer U sees an image of the pixel display light Ld projected onto the projection surface8(or more precisely, the second mirror surface82of the projection surface8). Further, because the irradiated position (unit area Au) of pixel display light Ld for each pixel on the projection surface8is switched sequentially per pixel at cycles that the viewer U is unable to perceive, the viewer U sees an image of the display image on the projection surface8.

Thus, in the present embodiment, the viewer can be made to perceive an image having a sense of depth that depends on the depth value Cz, since an image of the pixel display light Ld that has been reflected a number of times depending on the depth value Cz (i.e., the light path length has been adjusted according to the depth value Cz) is projected onto the projection surface8. In this configuration, a stereoscopic image with horizontal parallax as in conventional stereoscopic technology is unnecessary in principle. Consequently, the viewer can be made to perceive an image with a sufficient sense of depth (e.g., an image with a sense of depth equivalent to real scenery), without being restricted to horizontal parallax. Also, in order to generate a plurality of images with horizontal parallax, it is necessary to generate a stereoscopic image by synthesizing images of an object taken a plurality of times from different angles, or by performing various stereoscopic processes on a flat image as disclosed in Patent Document 1. However, according to the present embodiment, these operations can be rendered unnecessary. Further, in the case where a synthesized stereoscopic image composed of right-eye and left-eye images is used, the resolution of the image actually perceived by the viewer is approximately half the resolution of the original stereoscopic image, because of it being necessary to include a single image perceived stereoscopically by the viewer in both the right-eye image and the left-eye image. In contrast, a high definition image with high resolution can be displayed according to the present embodiment, since horizontal parallax does not need to be imparted on the display image.

In conventional stereoscopic technology (e.g., technology allowing the naked eye to perceive a sense of depth by using a mechanism such as a lenticular lens or a parallax barrier), the viewing position that enables a natural sense of depth to be perceived is limited. For this reason, the sense of depth that the viewer perceives at other positions may be unnatural, or the number of persons able to perceive a natural sense of depth may be severely limited. Further, even if the viewer U can be made to perceive a satisfactory sense of three-dimensionality in relation to part of an image (i.e., the middle), the sense of three-dimensionality perceived by the viewer U at the edges of the screen may be unnatural. In contrast, with the present embodiment, it is possible to allow a natural sense of depth to be perceived regardless of the position of viewer U, since the viewer U sees the image of pixel display light Ld that has been reflected a number of times depending on the depth value Cz. This is particularly favorable for displaying images in an environment (e.g., a theater) in which a large number of viewers U view images at the same time, because a natural sense of depth is obtained regardless of the viewing position relative to the projection surface8even when images are displayed on a large-scale projection surface8.

Incidentally, the area of the image of pixel display light Ld projected onto the unit areas Au of the projection surface8and seen by the viewer (i.e., the light flux cross-sectional area of the pixel display light Ld) decreases the longer the light path length traveled by the pixel display light Ld to the projection surface8; that is, the greater the reflected number of times in the reflector51. For example, even if an image Im of pixel display light Ld extends over the entire unit area Au as shown inFIG. 7(a), when reflected a small number of times in the reflector51, the image Im of pixel display light Ld will not extend over the entire unit area Au (i.e., the pixel display light Ld is only irradiated onto part of the unit area Au), as shown inFIG. 7(b), if the light flux cross-sectional area of the pixel display light Ld is substantively reduced as a result of the pixel display light Ld being mirror-reflected a large number of times in the reflector51. In this case, portions not irradiated with light occur around the boundaries of adjacent unit areas Au, possibly causing a drop in display quality of the image perceived by the viewer U. This problem is solved in the present embodiment by changing the traveling direction of the pixel display light Ld minutely within each unit interval.

That is, the control means45of the light path length control means4makes the adjustment reflecting member41oscillate in the X and Y directions in each unit interval at an amplitude Am that depends on the depth value Cz, after having driven the adjustment reflecting member41to an angle θ that depends on the depth value Cz as described above. That is, as shown inFIG. 3, the control means45makes the adjustment reflecting member41oscillate at a higher amplitude Am the larger the depth value Cz input from the acquiring means2(i.e., the greater the reflected number of times in the reflector51as shown inFIG. 7(b)). Here, amplitudes Am are associated with depth values Cz in the table TBL, as described above. The instruction means451constituting the control means45identifies a depth value Cz and an amplitude Am that depends on the pixel position by referring to the table TBL, and controls the voltage to the magnetic field generators452so that the adjustment reflecting member41oscillates at this amplitude Am. Now, assume a configuration in which the image Im of the pixel display light Ld on the projection surface8moves in the x direction inFIG. 7(b) when the adjustment reflecting member41is rotated in the X direction, and moves in the y direction inFIG. 7(b) when the adjustment reflecting member41is rotated in the Y direction. If the adjustment reflecting member41is minutely oscillated in the X and Y directions based on this configuration, the image Im of the pixel display light Ld will move over the entire unit area Au, as shown by the arrows inFIG. 7(b). This image Im of pixel display light Ld is assumed to move at a higher speed than the viewer U can perceive. For this reason, the image Im, when seen instantaneously, is perceived by the viewer U as extending over the entire unit area Au, despite only part of the unit area Au being irradiated as shown inFIG. 7(b). Consequently, excellent display quality is realized according to the present embodiment, irrespective of the light path length of the pixel display light Ld (i.e., the reflected number of times in the reflector51). Note that the values of the amplitudes Am in the table TBL are determined for each depth value Cz so that the image Im of pixel display light Ld that reaches the projection surface8moves over the entire unit area Au, as is clear from the above description. For example, an amplitude Am of “zero” is associated with depth values Cz at which the image Im of pixel display light Ld extends over the entire unit area Au as shown inFIG. 7(a), even without making the adjustment reflecting member41oscillate, while an amplitude Am that depends on the depth value Cz is associated with depth values Cz at which the image Im of pixel display light Ld only extends over part of the unit area Au as shown inFIG. 7(b), to the extent that the image Im does not cross over the peripheral border of the unit area Au following the movement.

In this way, a drop in display quality caused by a reduction in the light flux cross-sectional area of the pixel display light Ld can be suppressed according to the present embodiment, since the image Im of pixel display light Ld can be made to extend over the entire unit area AU, irrespective of the reflected number of times in the reflector51.

B. Second Embodiment

The configuration of a projection display system DS according to a second embodiment of the present invention is described next. The configuration of this projection display system DS is common with the above first embodiment except for the mode of the light path length control means4. In view of this, the same reference numerals are attached to those constitutional elements that are common with the above first embodiment, and description of these elements is omitted accordingly.

FIG. 8shows the configuration of the light path length control means4according to the present embodiment. An adjustment reflecting member42shown in this figure is, similarly to the adjustment reflecting member41in the above first embodiment, for guiding the pixel display light Ld output from the light output means3to the reflector51by reflecting the light. This adjustment reflecting member42is a disk-shaped member supported substantially horizontally so as be rotatable on a rotary shaft422, and has a mirror surface421for mirror-reflecting pixel display light Ld that reaches the surface thereof. The control means45rotates the adjustment reflecting member42on the rotary shaft422by an angle that depends on the depth value Cz. For example, the control means45has a motor whose output shaft is coupled to the rotary shaft422, and a circuit that controls the rotation angle of this output shaft to be at an angle that depends on the depth value Cz.

The surface of the adjustment reflecting member42has a substantially spiral shape whose angle relative to a horizontal surface changes continuously depending on the circumferential position. That is, in a cross-section seen from a line IXa-IXa inFIG. 8, the mirror surface421slopes at an angle θ1relative to the horizontal surface Ls as shown inFIG. 9(a), while in a cross-section seen from a line IXb-IXb inFIG. 8, the mirror surface421slopes at an smaller angle θ2than the angle θ1relative to the horizontal surface Ls as shown inFIG. 9(b). Further, in a cross-section seen from a line IXc-IXc inFIG. 8, the mirror surface421slopes at an smaller angle θ3than the angle θ2relative to the horizontal surface Ls as shown inFIG. 9(c). The position at which the pixel display light Ld is output from the light output means3is fixed regardless of the rotation angle of the adjustment reflecting member42, with the pixel display light Ld reaching the adjustment reflecting member42after traveling vertically downward. Consequently, the angle at which the pixel display light Ld is incident on the mirror surface421changes according to the rotation angle of the adjustment reflecting member42determined based on the depth value Cz, as shown inFIGS. 9(a) to9(c). As a result, the pixel display light Ld is incident on the reflector51after traveling in a direction that depends on the rotation angle of the adjustment reflecting member42(i.e., a direction that depends on the depth value Cz), similarly to the first embodiment.

The control means45changes the rotation angle of the adjustment reflecting member42according to the depth value Cz, so that the number of times the pixel display light Ld is reflected in the reflector51increases the larger the depth value Cz. Elaborating further, rotation angles of the adjustment reflecting member42are specified in the table TBL in the present embodiment as the drive contents corresponding to the depth values Cz (seeFIG. 5). The control means45retrieves the rotation angle associated with the depth value Cz input from the acquiring means2from the table TBL, and rotates the adjustment reflecting member42by this retrieved rotation angle. Note that the minute oscillation of the adjustment reflecting member42according to the depth value Cz (i.e., minute oscillation centered on the rotary shaft422) so as to make the image Im of the pixel display light Ld extend over the entire unit area Au is similar to the above first embodiment.

In this way, similar effects to the first embodiment are obtained in the present embodiment because the number of times the pixel display light Ld is reflected is also controlled according to the depth value Cz. Further, because the reflected number of times can be changed according to the present embodiment by controlling the rotation angle of the adjustment reflecting member42, the direction in which the pixel display light Ld travels can be adjusted with high accuracy and reliability using a simpler configuration than the above first embodiment.

The configuration of a projection display system DS according to a third embodiment of the present invention is described next. Note that the configuration of the projection display system DS according to the present embodiment is common with the above first embodiment except for the content of the table TBL. In view of this, the same reference numerals are attached to those constitutional elements that are common with the above first embodiment, and description of these elements is omitted accordingly.

Based on the configuration according to the first embodiment, a light path length (hereinafter, “output light path length”) Lb of the pixel display light Ld from the output reflecting member58to the projection surface8differs according to the positional relation between the unit area Au onto which the pixel display light Ld is projected and the output reflecting member58. For example, assume a case in which the projection display device D is disposed diagonally above the horizontal center of the projection surface8, as shown inFIGS. 10(a) and10(b). Note thatFIG. 10(b) equates to a figure viewing the projection surface8from the left side ofFIG. 10(a). In this case, an output light path length Lbmax of the pixel display light Ld to unit areas Au1positioned in the bottom left and right corners of the projection surface8(i.e., unit areas Au positioned farthest from the output reflecting member58) is longer than an output light path length Lbmin of the pixel display light Ld to a unit area Au positioned at the top center of the projection surface8(i.e., unit area Au positioned closest to the output reflecting member58). For this reason, even if the reflected number of times in the reflector51is changed according to the depth value Cz, the light path length of the pixel display light Ld from the light output means3to the projection surface8(i.e., total light path length including output light path length) may differ from the light path length that depends on the depth value Cz, according to the projected position of this pixel display light Ld. In this case, the viewer may be unable to perceive a natural sense of depth that directly reflects the depth value Cz. Particularly since the difference between the maximum output light path length Lbmax and the minimum output light path length Lbmin increases the larger the projection surface8, this problem becomes all the more noticeable. The present embodiment is a mode for solving this problem.

As described above in relation to the first embodiment, drive contents for each depth value Cz are stored in the table TBL of the control means45so that the reflected number of times in the reflector51depends on the depth value Cz. In the present embodiment, furthermore, the drive contents of the table TBL are selected so that differences in the output light path length depending on the projected position of the pixel display light Ld of pixels are compensated. To elaborate is as follows.

Now, take “L(Cz)” as a light path length selected so as to only be proportional to the depth value Cz (the light path length from the light output means3to the projection surface8in the above first embodiment), without reflecting differences in the output light path length Lb, and take “Lbij” as the output light path length of the pixel in the ith row of the jth column (i.e., the distance from the output reflecting member58to the unit area Au in the ith row of the jth column). In the present embodiment, the drive contents of the table TBL are selected so that a light path length (hereinafter, “pre-projection light path length”) La from the light output means3to the output reflecting member58via the adjustment reflecting member41and the reflector51equals the sum of the light path length L(Cz) that depends on the depth value Cz and a light path length differential ΔL obtained by subtracting the output light path length Lbij that depends on the pixel from the maximum output light path length Lbmax. That is, the angle θ of the adjustment reflecting member41is determined so that (pre-projection light path length La)=(light path length L(Cz) depending on depth value Cz)+(light path length differential ΔL)=(light path length L(Cz) depending on depth value Cz)+{(maximum output light path length Lbmax)−(light path length Lbij for each pixel)}, with the pixel display light Ld being incident on the reflector51at an angle of incidence that depends on this angle θ.

According to this configuration, a light path length (hereinafter, “total light path length”) L of the pixel display light Ld for each pixel from the light output means3to the projection surface8is (total light path length L)=(pre-projection light path length La)+(light path length Lbij for each pixel)=(light path length L(Cz) depending on depth value Cz)+{(maximum output light path length Lbmax)−(output light path length Lbij for each pixel)}+(output light path length Lbij for each pixel)=(light path length L(Cz) depending on depth value Cz)+(maximum output light path length Lbmax). In this way, differences in the output light path length Lb for each pixel are compensated, since the total light path length L is the sum of the light path length L(Cz) that depends on the depth value Cz and the maximum output light path length Lbmax, irrespective of the position of the unit area Au onto which the pixel display light Ld is projected. That is, if the same depth value Cz is given to pixels, for example, the viewer U perceives a common sense of depth irrespective of the position of the pixels, since the total light path length L of respective pixel display light Ld is substantially the same, irrespective of the position of the unit areas Au onto which the respective pixel display light Ld is projected. That is, the control means45in the present embodiment functions to correct the light path length of pixel display light Ld corresponding to the pixels (more specifically, the reflected number of times in the reflector51) according to the projected position of the pixel display light Ld.

Similar effects to the above embodiments are also obtained as a result of the present embodiment. In addition, the viewer U can be made to perceive a depth that directly reflects the depth value Cz of each pixel, since differences in the output light path length Lb that depend on the positional relation between the projection display device D and the projection surface8are compensated according to the present embodiment. Note that while the projection display device D according to the first embodiment is illustrated here, differences in the output light path length Lb can also be compensated using a similar configuration in the projection display device D according to the second embodiment.

Incidentally, the output light path length Lb is determined according to the positional relation between the projection display device D and the projection surface8(i.e., in particular, the distance between the output reflecting member58and each unit area Au). Consequently, the output light path length Lbij of the pixels and the maximum output light path length Lmax are selected in advance, having assumed that the projection display device D and the projection surface8are disposed in a prescribed relation, and the drive contents in the table TBL are selected in accordance with these light path lengths. Based on this configuration, however, differences in the output light path length Lb cannot be adequately compensated if the positional relation between the projection display device D and the projection surface8differs from the expected positional relation. Accordingly, a configuration can also be adopted in which the control means45identifies the positional relation between the projection display device D and the projection surface8, and calculates the output light path length Lbij of the pixels and the maximum output light path length Lbmax for the identified positional relation, before selecting the drive contents of the table TBL according to these light path lengths. For example, a configuration can be adopted in which the control means45identifies the positional relation between the projection display device D and the projection surface8based on an instruction from the viewer U. According to this configuration, differences in the output light path length Lb can be adequately compensated regardless of the positional relation between the projection display device D and the projection surface8.

Note that while a configuration is illustrated in the present embodiment in which the drive content in the table TBL is selected so as to compensate for differences in the output light path length of pixels, the configuration compensating for differences in the output light path length is arbitrary. For example, a configuration can also be adopted in which the depth values Cz are corrected according to the position of the unit areas Au onto which the pixel display light Ld of pixels is projected. For example, a correction means47that corrects the depth values Cz output from the acquiring means2according to the position of the pixels may be provided upstream of the control means45, as shown inFIG. 11. This correction means47corrects the depth values Cz input from the acquiring means2so that the depth values Cz decrease the longer the output light path length Lb (i.e., so that the depth values Cz increase the shorter the output light path length Lb). That is, with pixel display light Ld projected onto a unit area Au far from the projection display device D, the depth value Cz is substantively increased (the viewer U perceives greater depth) because of the longer output light path length Lb. Accordingly, in the configuration shown inFIG. 11, the increased sense of depth resulting from the pixel display light Ld traveling the output light path length Lb is subtracted in advance from the depth value Cz of the pixel. A natural sense of depth can also be realized with this configuration by compensating for differences in the output light path length Lb of the pixels.

The configuration of a projection display system DS according to a fourth embodiment of the present invention is described next. A configuration was illustrated in the above first embodiment in which an image Im of the pixel display light Ld is made to extend over the entire unit area Au by making the traveling direction of the pixel display light Ld oscillate minutely in the case of large depth values Cz. In contrast, in the present embodiment, the image Im is made to extend over the entire unit area Au by adjusting the light flux cross-sectional area of pixel display light Ld output from the light output means3according to the depth value Cz. Note that the configuration of the projection display system DS according to the present embodiment is common with the above first embodiment except for the configuration for solving the reduction in light flux cross-sectional area in the light path length of the pixel display light Ld. In view of this, the same reference numerals are attached to those constitutional elements that are common with the above first embodiment, and description of these elements is omitted accordingly.

As shown inFIG. 12, the light output means3of the present embodiment includes a light flux adjusting means35in addition to the same light source31and lens32as the above first embodiment. This light flux adjusting means35adjusts the light flux cross-sectional area of the parallel pixel display light Ld output from the lens32according to the depth value Cz output from the acquiring means2. Elaborating further, the light flux adjusting means35has a plate member351and a control means355. The plate member351is a disc-shaped member supported substantially horizontally so as to be rotatable on a rotary shaft352, and at least the plate surface opposing the lens32is made from a material that does not allow light to pass (material having light reflectivity or light absorbency). Further, the plate member351has a slit351athat extends circumferentially around the rotary shaft352. The slit351ais formed so that a slit width W changes continuously according to the circumferential position. As shown inFIG. 12, for example, a slit width Wa at one end of the slit351ais larger than a slit width Wb at the other end. The control means355rotates the plate member351on the rotary shaft352by an angle that depends on the depth value Cz. For example, the control means355has a motor whose output shaft is coupled to the rotary shaft352, and a circuit that controls the rotation angle of this output shaft to be at an angle that depends on the depth value Cz.

Although the position at which the pixel display light Ld is output from the light source31and the lens32is also fixed in the present embodiment, similarly to the above first embodiment, the light flux cross-sectional area of the pixel display light Ld output from the lens32is larger than the above first embodiment. The plate member351is provided so as to intersect the pixel display light Ld output from the lens32, and the slit351ais formed at a position through which the optical axis of the lens32passes in a radial direction around the rotary shaft352. Consequently, part of the pixel display light Ld irradiated from the lens32onto the plate member351selectively passes through the slit351aand is incident on the light path length control means4, while the remaining light is absorbed or reflected by the surface of the plate member351. Because the slit width W changes continuously in a circumferential direction as described above, the light flux cross-sectional area of the pixel display light Ld that is incident on the light path length control means4after passing through the slit351achanges according to the rotation angle of the plate member351.

Based on this configuration, the control means355changes the rotation angle of the plate member351so that the light flux cross-sectional area of the pixel display light Ld incident on the light path length control means4depends on the depth value Cz. For example, the control means355rotates the plate member351according to the depth value Cz, so that the light flux cross-sectional area of the pixel display light Ld increases the larger the depth value Cz (i.e., so that the light flux cross-sectional area of the pixel display light Ld decreases the smaller the depth value Cz). Here, the maximum slit width Wa of the slit351ain the case of the largest depth value Cz (i.e., the reflected number of times in the reflector51is maximized) is selected so that the image Im of pixel display light Ld that reaches the projection surface8after passing through this portion extends over the entire unit area Au. The minimum slit width Wb of the slit351ain the case of the smallest depth value Cz (i.e., the reflected number of times in the reflector51is minimized) is selected so that the image Im of the pixel display light Ld that reaches the projection surface8after passing through this portion fits within the unit area Au. Consequently, the image Im of the pixel display light Ld that reaches the projection surface8extends over the entire unit area Au irrespective of the depth value Cz (i.e., irrespective of the reflected number of times in the reflector51), as a result the rotation angle of the plate member351being controlled according to the depth value Cz. Note that the configuration in which the control means355controls the rotation angle of the plate member351according to the depth value Cz is arbitrary. For example, a configuration can also be adopted whereby a table in which depth values Cz are associated with rotation angles is prestored, and the plate member351is controlled so as to rotate to the rotation angle associated with the depth value Cz input from the acquiring means2, or whereby the rotation angle of the plate member351is calculated by performing a prescribed operation on the depth value Cz input from the acquiring means2, and the plate member351is driven so as to rotate to the calculated rotation angle.

According to the present embodiment, a drop in display quality is suppressed because of being able to make the image Im of pixel display light Ld extend over the entire unit area Au irrespective of the reflected number of times in the reflector51, in addition to obtaining similar effects to the above first embodiment. Also, given that the above first embodiment requires a configuration for making the adjustment reflecting member41oscillate minutely, the present embodiment is advantageous in that the above effect is achieved using a simple configuration in which the rotation angle of the plate member351is controlled according to the depth value Cz. Note that while the projection display device D according to the first embodiment is illustrated here, a drop in display quality is also suppressed using a similar configuration in the projection display devices D according to the second and third embodiments. Also, the light flux adjusting means35according to the present embodiment may also be provided in addition to a configuration for making the adjustment reflecting member41(or the adjustment reflecting member42of the first embodiment) oscillate according to the depth value as in the above first embodiment.

The configuration of a projection display system DS according to a fifth embodiment of the present invention is described next. The configuration of the projection display system DS according to the present embodiment is common with the above first embodiment except for the configuration of the screen S. In view of this, the same reference numerals are attached to those constitutional elements that are common with the above first embodiment, and description of these elements is omitted accordingly.

The angle at which the pixel display light Ld reflected by the output reflecting member58is incident on the first mirror surface81of the projection surface8differs according to the positional relation between the projection display device D and the projection surface8. When the positional relation between the projection display device D and the projection surface8is as shown inFIGS. 10(a) and10(b), for example, the angle at which the pixel display light Ld is incident on the first mirror surface81in the unit areas Au1positioned in the bottom left and right corners of the projection surface8(angle formed by the normal line of the first mirror surface81and the direction of incidence) is larger than the angle at which the pixel display light Ld is incident on the first mirror surface81in the unit area Au2positioned at the horizontal center of the projection surface8. For this reason, based on a configuration in which the first mirror surface81is a uniformly planar surface which is substantially parallel with a horizontal surface as in the above first embodiment, differences in the traveling direction of pixel display light Ld output from the first mirror surface81via the second mirror surface82may occur depending on the position on the projection surface8. Since the intensity and direction of light output on the viewing side varies for every position on the projection surface8, the viewer U in this case perceives this as display unevenness of the image. In particular, this problem becomes all the more noticeable if a large screen S is used, since the angles of incidence of the pixel display light Ld on the first mirror surface81vary greatly depending on the position on the projection surface8. The present embodiment is a mode for solving this problem. Note that in the following description, a case is assumed in which the projection display device D and the screen S are in the positional relation shown inFIGS. 10(a) and10(b).

FIG. 13(a) is a plan diagram showing the configuration of the screen S of the present embodiment seen from the front of the projection surface8.

FIG. 13(b) shows enlarged views of the portions circled with broken lines inFIG. 13(a). Note that while only portions on the left side of the projection surface8from the centerline are shown inFIG. 13(b), portions on the right side of the projection surface8have a symmetrical configuration about the centerline Cl. As shown in these diagrams, the screen S in the present embodiment is common with the screen S of the above first embodiment in terms of having a projection surface8composed of a first mirror surface81and a second mirror surface82disposed alternately. However, the angle formed by the first mirror surface81and the horizontal surface Ls differs depending on the position on the projection surface8.

As shown inFIG. 13(b), the first mirror surface81is divided horizontally into a plurality of portions Pu (hereinafter, “unit portions”). Note that while portions obtained by dividing the first mirror surface81per unit area Au may be used as the unit portions Pu, the dimension of the unit portions Pu may be selected independently of the unit areas Au. An angle β that the surface of each unit portion Pu (i.e., the first mirror surface81) forms with the horizontal surface Ls (e.g., βb, βc) is selected for every unit portion Pu according to the angle of incidence of the pixel display light Ld on respective unit portions Pu. More specifically, the angle β formed with the horizontal surface Ls is selected for each unit portion Pu, so that the reflected light of the unit portion Pu is output parallel on the viewing side after being reflected by the second mirror surface82. For example, assume a case in which the reflected light of the first mirror surface81reaches the second mirror surface82after traveling perpendicularly, seen from a direction perpendicular to the projection surface8. Because the pixel display light Ld is incident on the unit portion Pu shown in portion A ofFIG. 13(a) in a direction substantially perpendicular to the horizontal surface Ls, this unit portion Pu is a plane which is substantially parallel with the horizontal surface Ls as shown in portion A ofFIG. 13(b). The pixel display light Ld is incident on the unit portion Pu shown in portion B ofFIG. 13(a) in a direction forming an angle γb with the normal of the horizontal surface Ls, as shown in portion B ofFIG. 13(b). For this reason, the unit portion Pu shown of portion B is a planar surface forming an angle βb with the horizontal surface Ls. The angle βb of portion B is roughly half of the angle γb of the pixel display light Ld, as is clear fromFIG. 13(b). For the same reason, an angle βc that the unit portion Pu shown in portion C ofFIG. 13(b) forms with the horizontal surface Ls is roughly half of an angle γc which pixel display light Ld reaching this portion forms with the normal of the horizontal surface Ls. Because the angle γ (e.g., γb, γc) that the pixel display light Ld reaching each unit portion Pu makes with the normal of the horizontal surface Ls increases the further the position from the centerline Cl of the projection surface8, the angle β that each unit portion Pu forms with the horizontal surface Ls is selected so as to increase the further the position from the centerline Cl of the projection surface8. Note that while the slope of the unit portions Pu in the horizontal direction of the projection surface8is illustrated here, the slope of the unit portions Pu in the anteroposterior direction of the projection surface8is also selected based on a similar viewpoint. That is, in the case where the projection display device D is disposed diagonally above the projection surface8as in the present embodiment, the anteroposterior angle that each unit portion Pu forms with the horizontal surface Ls is selected so as to increase the closer the position to the bottom of the projection surface8(to decrease the closer the position to the top of the projection surface8).

In this way, in the present embodiment, the display quality of an image seen by the viewer U can be homogenized in all portions of the projection surface8because of being able to output the pixel display light Ld in an anticipated direction on the viewing side, irrespective of the position on the projection surface8. In other words, the projection surface8can be enlarged while maintaining the display quality at a high level at which display unevenness is suppressed. Note that while the projection display device D according to the first embodiment is illustrated here, display unevenness can also be suppressed using a similar configuration in the projection display devices D according to the second to fourth embodiments.

Incidentally, a configuration is illustrated here in which the angles of the unit portions Pu are fixed in advance, having assumed that the projection display device D and the projection surface8are in an expected positional relation. However, based on this configuration, display unevenness may not be adequately suppressed if the positional relation of the projection display device D and the projection surface8differs from the expected positional relation. Accordingly, a configuration is possible in which the angles of the unit portions Pu in the projection surface8are adjusted arbitrarily. For example, a configuration can be adopted in which the projection surface8is constituted by arranging a large number of micro-mirror elements in sheets, and a control means that is not shown individually controls the angle of micro mirrors in the micro-mirror elements. Based on this configuration, once the viewer has input the positional relation between the projection display device D and the projection surface8, the control means calculates the angle of incidence of the pixel display light Ld for each unit portion Pu of the projection surface8based on the input positional relation, and adjusts the angle of the micro mirrors according to these angles of incidence. According to this configuration, display unevenness in the projection surface8can be adequately suppressed, regardless of the positional relation between the projection display device D and the projection surface8.

The configuration of a projection display system DS according to a sixth embodiment of the present invention is described next. The configuration of the projection display system DS according to the present embodiment is common with the above first embodiment except for the configuration of the screen S. In view of this, the same reference numerals are attached to those constitutional elements that are common with the above first embodiment, and description of these elements is omitted accordingly.

Based on a configuration in which the second mirror surface82is a plane as shown in the above first embodiment (seeFIG. 1), a viewer positioned in front of the screen S is able view the anticipated image with a sense of three-dimensionality, since the incident light from the first mirror surface81reaches the viewer after being reflected in the direction of the normal of the projection surface8. However, if the viewer views the image displayed on the screen S from a diagonal direction (diagonally from the left/right or above/below), the viewer may not be able to see the image because the light reflected by the screen S is not output in that direction or because of insufficient light intensity.

This drawback is solved in the present embodiment by making the second mirror surface82a curved surface for every unit area Au, as shown inFIG. 14(a). Note thatFIG. 14(a) collectively illustrates a front view of the first mirror surface81and the second mirror surface82seen from a direction perpendicular to the projection surface8(i.e, the horizontal direction), an end view of these mirrors fractured at a vertical cross-section (B-B′ line cross-section), and an end view seen from a horizontal cross-section (C-C′ line cross-section). As shown in this figure, the second mirror surface82corresponding to each unit area Au is a smooth curve, a vicinity of the center of which protrudes more on the viewing side than the periphery thereof (i.e., a surface in which the periphery of a cross-section thereof in either the horizontal or vertical directions forms a curve). Because incident light from the first mirror surface81is output not only in the direction of the normal of the screen S but dispersedly over a wide area (e.g., diagonally seen from the screen S) according to this configuration, sufficient reflected light that depends on the display image is also made to reach a viewer of the screen S diagonally.

Note that while a case was assumed here in which the viewer views the image diagonally from the left/right or above/below relative to the normal of the screen S, there is little necessity to reflect light upwards or downwards relative to the normal of the screen S provided that the position of the viewer above or below the screen S is substantially fixed. Accordingly, the surface of the second mirror surface82in this case may be a curve with only horizontal curvature, as shown inFIG. 14(b), instead of the configuration shown inFIG. 14(a) (i.e., only the periphery of the horizontal cross-section (line C-C′) forms a curve, while the periphery of the vertical cross-section (line D-D′) is a straight line). According to this configuration, because incident light from the first mirror surface81can be output dispersedly in a direction forming a horizontal angle with the normal of the screen S (i.e., diagonally to the left/right seen from the screen S), sufficient reflected light that depends on the display image can also be made to reach a viewer of the screen S diagonally from the left or right. Also, in the case where light is output diagonally upwards or downwards relative to the normal of the screen S, the surface of the second mirror surface82may be a curve with only vertical curvature, as shown inFIG. 14C(i.e., only the periphery of the vertical cross-section (line F-F′) forms a curve, while the periphery of the horizontal cross-section (line E-E′) is a straight line).

While a configuration was illustrated in the above embodiments in which an image is projected onto a single projection surface8by a single projection display device D, the correspondence relation between the projection surface8and the projection display device D is arbitrary. In a projection display system DS of the present embodiment, a plurality of projection display devices D project images onto a single projection surface8(screen S), as shown inFIG. 15. Note that the same reference numerals are attached to those constitutional elements that are common with the above first embodiment, and description of these elements is omitted accordingly.

In this configuration, the projection display devices D project an image onto each of a plurality of areas into which the projection surface8is divided. According to this configuration, it is possible to enlarge the projection surface8in comparison to when only a single projection display device D is used. Note that while a configuration can also be adopted in which each projection display device D independently includes all of the constitutional elements shown inFIG. 1, a configuration is possible in which a management device86is provided for comprehensively managing the operation of the projection display devices D, as shown inFIG. 15. This management device86includes the storage means1, the acquiring means2and the control means45out of the constitutional elements shown inFIG. 1, and outputs pixel values Cg and depth values Cz to the projection display devices D. Each projection display device D shown inFIG. 15has the light output means3, the adjustment reflecting member41, and the light guide body5. According to this configuration, the storage means1, the acquiring means2and the control means45do not need to be set up independently for each projection display device D, thereby allowing for simplification of the configuration and reduction of manufacturing costs. Also, the entire screen S does not necessarily need to be integrated. For example, the projection surface8can be easily enlarged if a screen S composed of a plurality of interlinked portions is used. A projection display system DS that displays an image using any of the modes shown below, for example, may also be realized if a configuration is applied in which a plurality of projection display devices D project images onto a single projection surface8, as shown inFIG. 15.

G-1. First Mode

In the present mode, nine types of images having a common object are respectively projected onto the projection surface8of the screen S from a total of nine projection display devices D. The nine types of images are generated by imaging the common object Ob using a total of nine imaging devices6(6-1,6-2,6-3,6-4,6-5,6-6,6-7,6-8and6-9), as shown inFIG. 16. These imaging devices6are disposed in different positions from each other seen from the object Ob (in particular, the directions seen from the object Ob are different from each other). That is, the imaging device6-1is disposed diagonally to the upper left of the object Ob facing the object Ob, the imaging device6-2is disposed diagonally above the object Ob, the imaging device6-3is disposed diagonally to the upper right of the object Ob, the imaging device6-4is disposed diagonally to the right of the object Ob, the imaging device6-5is disposed in front of the object Ob, the imaging device6-6is disposed diagonally to the left of the object Ob, the imaging device6-7is disposed diagonally to the bottom left of the object Ob, the imaging device6-8is disposed diagonally below the object Ob, and the imaging device6-9is disposed diagonally to the bottom right of the object Ob. The images taken by these imaging devices are respectively input to different projection display devices D and projected onto the projection surface8. The projection display devices D project the images onto the projection surface8from positions corresponding to the positions of the imaging devices6during the imaging. That is, the projection display device D input with an image taken by the imaging device6-1projects the image diagonally from the upper left of the projection surface8, the projection display device D input with an image taken by the imaging device6-2projects the image from diagonally above the projection surface8, and the projection display device D input with an image taken by the imaging device6-3projects the image diagonally from the upper right of the projection surface8. The positions of the other projection display devices D are also similarly selected according to the positions of the imaging devices6. According to the projection display system DS of the present mode, the viewer can be made to perceived images having a natural sense of three-dimensionality irrespective of the position of the viewer relative to the projection surface8, since the reflected light of images taken of the object Ob from various positions reaches the viewer situated at these positions relative to the projection surface8.

Note that while a configuration is illustrated here in which images taken of a common object Ob are projected onto the projection surface8from the projection display devices D, separate images may be projected from each projection display device D. For example, various images such as the images of programs on various channels provided by a television broadcast, or images output from an image playback device such as a video tape recorder may be respectively projected onto the projection surface8from separate projection display devices. According to this configuration, different images can be seen depending on the position of the viewer relative to the projection surface8. Also, while a configuration is illustrated inFIG. 16in which an object Ob is imaged from nine imaging devices6, the number of imaging devices6is arbitrary. Consequently, the number of the projection display device D for projecting images taken by the imaging devices6onto the screen S is also arbitrary.

G-2. Second Mode

While a configuration was illustrated in the above embodiments in which the projection surface8is a substantially planar surface, a projection display system DS according to the present mode includes a substantially cylindrical screen S whose projection surface8is a curved surface as shown inFIG. 17, and has an outer shape that is substantially columnar as a whole. As shown in this figure, the projection display system DS has a hollow casing70. This casing70is composed of a substantially disk-shaped support base71set on the floor, a substantially cylindrical protective member73that is fixed to the support base71and stands vertically upright so that one of the substantially annular end faces follows the periphery of the upper surface of the support base71, and a support cover75fixed to the other end face of the protective member73so as to block the opening of the protective member73. The protective member73is formed using a material with optical transparency (i.e., transparent member), with the viewer being able to see inside the casing70through the protective member73. The support base71and the support cover75do not have optical transparency (i.e., opaque members). The plate surface of the support cover75opposing the support base71is a reflecting surface751having light reflectivity (i.e., plate surface facing vertically downward). For example, a reflecting plate is stuck to the plate surface of the support cover75opposing the support plate71.

The screen S formed into a substantially cylindrical shape is housed inside this casing70, with the outer surface of this screen S (i.e., the plate surface opposing the protective member73) forming the projection surface8. Further, a plurality of projection display devices D are disposed on the inside of the substantially cylindrical screen S. The projection display devices D are disposed on the upper surface of the support base71so that light output from the output reflecting member58reaches the reflecting surface751of the support cover75. Based on this configuration, light output from the projection display devices D reaches the projection surface8of the screen S after being reflected by the reflecting surface751of the support cover75, and from there the light passes through the protective member73and is output to the outside of the casing70. A viewer situated outside the casing70perceives an image with a sense of three-dimensionality as a result of seeing this output light. Here, the position and orientation of each of the plurality of the projection display devices D are selected so that light output from each device is irradiated dispersedly onto the projection surface8of the screen S, or more preferably, so that the light is irradiated over the entire projection surface8of the screen S. According to this configuration, the user is able to see an image having a sense of three-dimensionality for 360 degrees around the casing70.

Note that while the above protective member73constituting the lateral face of the casing70is made entirely of a transparent material inFIG. 17, a portion731corresponding to a segment of the protective member73from the upper end face of the screen S to the support cover75may be opaque. For example, a configuration can be adopted in which the portion731of the configuration shown inFIG. 17is covered with a member that does not have optical transparency (i.e., a member having opacity). According to this configuration, the visibility of the display image on the projection surface8can be improved because of being able to block light that is reflected by the reflecting surface751and travels to the outside of the casing70without passing via the projection surface8.

Also, while a configuration is illustrated here in which an image is viewed from outside the screen S, a configuration can also be adopted in which the viewer views the image from inside the screen S, after having made the screen S large enough for the viewer to go inside. In this configuration, the inner surface of the screen (i.e., the plate surface on the opposite side to the plate surface opposing the protective member) forms the projection surface8, and the plurality of projection display devices D are disposed so that light output from the projection display devices D reaches the projection surface8via the reflecting surface. Note that a configuration is possible in which the projection display devices D are disposed outside the screen S (i.e., in the space sandwiched between the outer surface of the screen S and the protective member). Also, while a configuration is illustrated in the present mode in which the screen S is housed in a casing, this casing can be omitted accordingly.

Various modifications can be made to the above embodiments. The modes of specific modifications are as follows. Note that a configuration can also be adopted in which the above embodiments and the following modes are combined accordingly.

(1) Although a reflector51composed of reflecting members511disposed opposite each other is illustrated in the above first embodiment, the configuration of the reflector in the present invention is arbitrary. For example, a tubular member (here, cylindrical) with mirror surfaces511aformed on the inner surface may be adopted as a reflector52, as shown inFIG. 18(a). In this configuration, the pixel display light Ld output from the light path length control means4is incident on the inside of the reflector52, and reaches the output reflecting member58after being sequentially reflected by the mirror surfaces511aformed on the inner surface of the reflector52. Also, it is not absolutely necessary for the mirror surfaces511ain the reflector to be parallel with each other. For example, a reflector53whose reflecting members511are opposed so that the distance therebetween varies depending on the position (i.e., a reflector53in which one of the reflecting members511slopes relative to the other reflecting member511) can also be adopted, as shown inFIG. 18(b), or a (tapered) tubular member whose diameter changes continuously from one end to the other end may be used as a reflector54, as shown inFIG. 18(c). That is, there are no objections regarding the specific mode of the reflector in the present invention, provided that the configuration has light reflecting surfaces opposing each other (mirror surfaces511a). Also, while a configuration was illustrated in the above embodiments in which light output from the reflector51(or52,53,54) is output to the screen S via the output reflecting member58, a configuration is possible in which light output from the reflector51reaches the screen S directly (i.e., without passing via other members such as the output reflecting member58).
(2) Although a light output means3that adopts light-emitting diodes of different colors as a light source31is illustrated in the above embodiments, the configuration of this means is arbitrary. For example, a device composed of an illuminator (back light) that outputs white light, and an LCD panel that adjusts the light intensities of portions corresponding to the colors red, green and blue to light intensities specified by the pixel values Cg may be adopted as the light source31. In short, there are no objections regarding the specific configuration of the light source31, provided the light source31outputs pixel display light Ld whose wavelength components corresponding to the different colors have light intensities that depend on the pixel values Cg. Note that the configuration for adjusting the light intensity per color is not necessary in a projection display device D that displays monochrome images. A configuration in which pixel display light Ld is output at a light intensity that depends on gradations specified as pixel values Cg is sufficient. As is also clear from this, a “pixel value” equates to information showing the light intensity for different colors in a configuration that displays color images, and equates to information showing gradations in a configuration that displays monochrome images. Also, the lens32shown in the above embodiments is not an essential element of the present invention and may be omitted accordingly.
(3) Although a configuration was illustrated in the above embodiments in which the acquiring means2reads pixel values Cg and depth values Cz from the storage means1, the configuration in which the acquiring means2acquires pixel values Cg and depth values Cz is not limited to this. For example, a configuration is possible in which only the pixel value Cg for each pixel is stored in the storage means1, and the acquiring means2calculates the depth values Cz based on these pixel values Cg. A configuration is also possible, for example, in which the gradation values of the colors red, green and blue specified by the pixel values Cg are weighted accordingly, after which gray scales are calculated by summing these gradation values, and the calculated gray scales are output to the light path length control means4(or the control means355in the fourth embodiment) as depth values Cz. Further, various types of correction may be performed on the gray scales and the numeric values after correction adopted as depth values Cz. The method of calculating the depth values Cz in this configuration is arbitrary. Also, the acquisition source of the pixel values Cg and the depth values Cz is not limited to the storage means1. For example, a configuration is possible in which the acquiring means2acquires pixel values Cg and depth values Cz input from an external source. A configuration is also possible, for example, in which the acquiring means2receives pixel values Cg and depth values Cz from another communication device connected via a network. Thus, there are no objections regarding the acquisition source and method, provided the acquiring means2in the present invention acquires the pixel values Cg and depth values Cz of pixels.
(4) Although a configuration was illustrated in the above embodiments in which an image is projected by disposing a projection display device D on the viewing side relative to the screen S, the projection display device D may be disposed on the side opposite the viewing side (hereinafter, “backside”), as shown inFIG. 19. In the configuration shown in this figure, the projection surface8is provided on the backside of the screen S, and the second mirror surface82of this projection surface8is a half mirror (semi-transmissive reflecting layer). Consequently, part of the pixel display light Ld that arrives at the second mirror surface82from the backside of the screen S passes selectively though the second mirror surface82(the remainder is reflected). The first mirror surface81is a substantially horizontal mirror surface as shown in the above embodiments. According to this configuration, pixel display light Ld that passes through the second mirror surface82is reflected onto the second mirror surface82by the first mirror surface81, and part of this light is reflected again by the second mirror surface82and output on the viewing side.

Also, the projection display device D and the screen S may be integrated, as shown inFIG. 20. In the configuration shown inFIG. 20, a substantially rectangular parallelepiped casing6is provided with an opening61in one surface (on the viewing side), and a projection display system DS as shown in the above embodiments is housed in the casing6. This projection display system DS projects an image from the backside of the screen S, as described with reference toFIG. 19. The screen S is fixed inside the casing6so as to block the opening61, and has a reflecting member82, a transmission member83and a plurality of illuminating devices85. The transmission member83is a plate-shaped member having optical transparency, and a vicinity of the ends thereof is fixed along the periphery of the opening61. The reflecting member82is provided on the plate surface at the backside of the transmission member83and constitutes the projection surface8, with the first mirror surface81and second mirror surface82being arranged alternately. The first mirror surface81is a substantially horizontal mirror surface that mirror-reflects the pixel display light Ld. The second mirror surface82is a half mirror that transmits only part of the pixel display light Ld and reflects the rest, and is provided so as to form a predetermined angle (e.g., 45 degrees) with the first mirror surface81. Also, each of the plurality of illuminating devices85outputs white light towards the center of the projection surface8. These illuminating devices85, seen from the viewing side, are buried so as to surround the projection surface8in sections of the transmission member83covered by the casing6. Based on this configuration, pixel display light Ld that is output from the projection display device D and passes through the second mirror surface82is reflected onto the second mirror surface82by the first mirror surface81, and then output on the viewing side and seen by the viewer U after again being reflected and passing through the transmission member83. The brightness of the image can be maintained at a high level since white light from the illuminating devices85is output at this time.

(5) Although a configuration was illustrated in the above embodiments in which the number of times the pixel display light Ld is reflected by the reflector51(or52,53,54) is controlled by the control means45driving the adjustment reflecting member41or42, the configuration for controlling the light path length of the pixel display light Ld from the light output means3to the projection surface8according to the depth values Cz is not limited to this. For example, a configuration can also be adopted in which the angle at which the pixel display light Ld is incident on the reflector51is changed by controlling the orientation of the light output means3according to the depth values Cz after having fixed the angle of the adjustment reflecting member41(or after having made the orientation variable as in the above embodiments), and thereby changing the reflected number of times in the reflector51according to the depth values Cz.

Also, while a configuration was illustrated in the above embodiments in which an image with a sense of three-dimensionality is displayed by controlling the light path length from the light source31to the projection surface8, a configuration can also be additionally adopted that makes it possible to display an image without controlling the light path length according to the depth values Cz. For example, a configuration is possible in which a 3D display mode and a normal display mode are switched according to an operation on an input device by the user, with an image being displayed in the 3D display mode by controlling the light path length from the light source31to the projection surface8according to the depth values Cz (image in which a sense of three-dimensionally is perceived by the user), as shown in the above embodiments, and an image being displayed in the normal display mode without controlling the light path length according the depth values Cz (i.e., image in which a sense of three-dimensionally is not perceived by the user). The operation in the normal display mode is arbitrary, although a configuration can be adopted in which the adjustment reflecting member41is driven so that the reflected number of times in the reflector51is constant irrespective of the depth values Cz, or in which the adjustment reflecting member41is driven so that light reflected by the adjustment reflecting member41reaches the output reflecting member58without passing through the reflection in the reflector51.

(6) The acquiring means2and the control means45(more specifically, the instruction means451) of the projection display device D according to the above embodiments may be realized by cooperation between a hardware device such as a CPU (central processing unit) and a computer program, or by a dedicated circuit manufactured on the premise that the circuit be mounted in the projection display device D. Also, while a configuration was illustrated in the above embodiments in which the drive content of the adjustment reflecting member41(or42) is identified based on the table TBL, the method for identifying this drive content according to the depth values Cz (consequently, a method for identifying the reflected number of times in the reflector51) is arbitrary. For example, a configuration can also be adopted in which the angle of the adjustment reflecting member41or the rotation angle of the adjustment reflecting member42is identified by performing an operation on the depth values Cz output from the acquiring means2using a prescribed arithmetic expression. Also, the configuration of the adjustment reflecting member41is arbitrary. For example, a configuration can also be adopted in which a known digital micro mirror device composed of arrayed micro mirror elements is used as the adjustment reflecting member41. In this configuration, similar effects to the above embodiments are obtained if a configuration is adopted in which the angle of the micro mirrors of the micro mirror elements is controlled according to the depth values Cz.