Projector capable of projection in different positions in the depth direction

A projector capable of simultaneous or concurrent projection in different positions in the depth direction. The projector includes a plurality of display sections each of which forms a collimated image light ray, a superimposing optical system that superimposes the image light rays having exited out of the plurality of display sections on one another with the image light rays unfocused, a projection optical system that projects an image corresponding to the image light rays superimposed by the superimposing optical system, and a circuit apparatus that causes the image light rays to exit out of local image source areas set in the plurality of display sections to shift a position where the image light rays are superimposed on one another to a plurality of superimposition positions different from one another along an optical axis.

The entire disclosure of Japanese Patent Application No. 2014-063249, filed Mar. 26, 2014 is expressly incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a projector capable of projection in different positions in the depth direction

BACKGROUND ART

In a projector of related art, since a projection optical system that enlarges and projects an image on a planar display element is used, a plane where focus is achieved is a substantially flat plane, and allowed adjustment is only shifting the position of the plane forward or rearward. That is, simultaneous or concurrent projection in spaces having different depth ranges is not allowed, and there has been no projector capable, for example, of performing projection on a curved screen with focus maintained over the surface or coping with a change in the shape of the curved screen.

Meanwhile, there is a technology that allows an imaging apparatus to acquire information on the direction of light incident on a two-dimensional sensor and simultaneously capture images of subjects separate from each other in the depth direction (PTL 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

The invention has been made in view of the circumstance described above, and an object of the invention is to provide a projector capable of simultaneous or concurrent projection in different positions in the depth direction.

In order to achieve the object described above, a projector according to the invention includes a plurality of display sections each of which forms a collimated image light ray, a superimposing optical system that superimposes the image light rays having exited out of the plurality of display sections on one another with the image light rays unfocused, a projection optical system that projects an image corresponding to the image light rays superimposed by the superimposing optical system, and a display controller that causes the image light rays to exit out of local image source areas set in the plurality of display sections to set a position where the image light rays are superimposed on one another to a plurality of superimposition positions different from one another along an optical axis.

In the projector described above, the projection optical system projects an image superimposed by the superimposing optical system, and the display controller sets the position where the image light rays are superimposed on one another to a plurality of superimposition positions different from one another along the optical axis, whereby simultaneous or concurrent projection in spaces having different depth ranges can be performed through the projection optical system. Further, in the projection optical system, the position where the image light rays are superimposed on one another is conjugate with a projection receiving position, and adjustment of the superimposition position allows adjustment of the projection receiving position along the optical axis.

In a specific aspect of the invention, in the projector described above, the superimposing optical system includes a plurality of lens elements facing the plurality of display sections and a superimposing lens that superimposes the image light rays having passed through the plurality of lens elements on one another in such a way that the image light rays are concentrated. In this case, each of the lens elements can adjust the degree of convergence of the image light ray from the corresponding display section, whereby the superimposing lens can superimpose the image light rays from the plurality of display sections on one another in such a way that the image light rays are concentrated.

In another specific aspect of the invention, in each of the display sections, the center of the image source area is set in a position shifted from a standard position that is a reference in accordance with a relative arrangement of the display section and the setting of the superimposition position. In this case, the superimposition position can be relatively readily set by shifting the center of each of the image source areas.

In still another specific aspect of the invention, in each of the display sections, the amount of shift of the center of the image source area from the standard position is roughly proportional to the distance from a center through which the optical axis of the superimposing optical system passes to the center of the display section. In this case, the image light rays from the display sections are allowed to be concentrated precisely at a single location.

In still another specific aspect of the invention, a plurality of images to be displayed in the plurality of display sections are each a basic image deformed in accordance with the deviation from the center. As a result, an image formed in the superimposition position can be a sharp image with a small amount of blur.

In still another specific aspect of the invention, in each of the display sections, when the center of the image source area coincides with the standard position, the superimposition position is conjugate with the display section with respect to the superimposing optical system.

In still another specific aspect of the invention, the plurality of display sections correspond to a plurality of portions formed in a single display element or a plurality of display elements.

In still another specific aspect of the invention, the plurality of display sections have transmissive display elements and an illuminator that illuminates the display elements. In this case, the compact display sections allow formation of a bright image and projection of the bright image.

In still another specific aspect of the invention, the illuminator includes a surface-emitting laser. In this case, the compact illuminator can output collimated illumination light, and the transmissive display elements therefore readily allow collimated image light rays to exit.

In still another specific aspect of the invention, the plurality of display sections have a light ray selection section that includes a pair of lens arrays and a pinhole array sandwiched therebetween and selectively transmit image light rays parallelized by the light ray selection section. In this case, the image light rays can be more precisely collimated.

In still another specific aspect of the invention, the display controller changes the superimposition position in a time division manner to allow the projection optical system to perform projection in projection positions over a three-dimensional range. In this case, an image can be projected on a surface having a stereoscopic shape.

In still another specific aspect of the invention, the display controller causes the plurality of display sections to display motion images in the image source areas.

DESCRIPTION OF EMBODIMENTS

First Embodiment

A projector2according to a first embodiment of the invention includes an optical system unit50, which projects image light, and a circuit apparatus80, which controls the operation of the optical system unit50, as shown inFIG. 1.

The optical system unit50includes an illuminator10, a display device20, a superimposing optical system30, and a projection optical system40.

In the optical system unit50, the illuminator10outputs precisely collimated illumination light LI through an output surface10a, which is parallel to an XY plane perpendicular to an optical axis OA. In this case, the illumination light LI is outputted in a Z direction, which is parallel to the optical axis OA, as a whole and as an optical element. The illuminator10includes a surface-emitting laser as a light source. The surface-emitting laser is formed of laser devices that emit three or more color light beams including RGB light beams and are two-dimensionally arranged, for example, at intervals of several μm, and the illumination light LI outputted through the output surface10ais uniformly distributed in the XY plane.

The display device20is a component having a plurality of display sections21two-dimensionally arranged in parallel to the XY plane, as shown inFIG. 2(A). In the example shown inFIG. 2(A), the display device20has a large number of display sections21arranged in a matrix of 5 rows and 5 columns with no gap therebetween. Each of the display sections21has a liquid crystal panel21aand a light blocking frame21b. The liquid crystal panel21ais a transmissive light modulator in which a liquid crystal material is sandwiched between a pair of light transmissive substrates, and the liquid crystal panel21ais accompanied by polarizing filters that are not shown but are disposed at the light incident and exiting surfaces. The liquid crystal panel21ahas a large number of pixels that allow two-dimensional image display and includes color filters on a pixel basis. The liquid crystal panel21adoes not perform display operation over an entire display area A0but performs display operation only in a local image source area AS of the entire display area A0. Each of the image source areas AS has a circular shape in the example shown inFIG. 2(A)for ease of illustration but can have an arbitrary shape including a rectangular shape and other polygonal shapes.

The image source area AS is set in each of the display sections21, which are two-dimensionally arranged. In a basic display mode, each of the image source areas AS is disposed at the center of the entire display area A0, which is a standard position on a divided optical axis OA1, as shown inFIG. 2(A). That is, the center of each of the display sections21coincides with the divided optical axis OA1, and the center of each of the image source areas AS also coincides with the divided optical axis OA1. In another display mode (in a case where projection is performed in a closer position), as will be described later in detail, each of the image source areas AS is disposed in a position that deviates from the position of the divided optical axis OA1so that the image source area AS shifts off the optical axis OA in accordance with the distance between the divided optical axis OA1and the optical axis OA, as shown inFIG. 3(B). In still another display mode (in a case where projection is performed in a more distant position), each of the image source areas AS is disposed in a position that deviates from the divided optical axis OA1so that the image source area AS approaches the optical axis OA in accordance with the distance between the divided optical axis OA1and the optical axis OA, as shown inFIG. 4(B).

Referring back toFIG. 1, the superimposing optical system30includes a lens array31, which has a plurality of lens elements31afacing the plurality of display sections21, and a superimposing lens33, which causes image light rays IM having passed through the plurality of lens elements31ato concentrate at a point on the optical axis OA so that the image light rays IM are superimposed on one another.

Each of the lens elements31a, which form the lens array31, is a convex lens having a contour shape that is substantially the same as the contour of the corresponding display section21of the display device20, as shown inFIG. 2(B). The lens elements31ahave substantially the same power and are so aligned with the display sections21and arranged that the lens elements31aand the display sections21share the same divided optical axes OA1. The superimposing lens33superimposes the image light rays IM having passed through the plurality of lens elements31ain such a way that the image light rays IM are concentrated at the same location on the optical axis OA. The superimposing lens33deflects the image light rays IM from the lens elements31ain such a way that an image light ray IM separate farther away from the optical axis OA (image light ray IM2, for example) is deflected by a greater amount. The position where the image light rays IM intersect the optical axis OA is a conjugate position PC, which is conjugate with the display sections21with respect to the superimposing optical system30. In the example shown inFIG. 1, image light rays IM0, IM1, and IM2from the corresponding display sections21are incident on the conjugate position PC and superimposed on one another. The plane in the conjugate position PC is a projection front focal plane FC set on the upstream side or in a position upstream of the projection optical system40, and a relatively bright small image G1is formed in the projection front focal plane FC. The small image G1spreads in the XY plane and has a two-dimensional optical intensity distribution. The image light rays IM0, IM1, and IM2are concentrated on the optical axis OA in the conjugate position PC or the projection front focal plane FC but are not focused or convergent to a single point.

The projection optical system40shown inFIG. 1is an enlarging projection lens having a fixed focal length and enlarges and projects the small image G1, which has been formed by the image light rays IM superimposed on one another by the superimposing optical system30, on a screen SC.

FIG. 3(A)shows a case where an image is projected on a screen SC1or a projection receiving object disposed in a position relatively close to the projector2, andFIG. 3(B)shows the image source areas AS set in the display sections21or the liquid crystal panels21a. In the close-range projection, the image source areas AS in the liquid crystal panels21aarranged in a matrix are so disposed that the image source area AS in a liquid crystal panel21acloser to the periphery is shifted outward by a greater amount, as shown inFIG. 3(B). More specifically, each of the image source areas AS is shifted away from the optical axis OA with reference to the standard position corresponding to the divided optical axis OA1shown inFIG. 2(A). Further, the amount of shift described above depends on the relative position of the liquid crystal panel21aand increases in proportion to the distance from the optical axis OA to the liquid crystal panel21a. As a result, since the image light rays IM0, IM1, and IM2intersect the optical axis OA in a position upstream of the conjugate position PC, they intersect the optical axis OA also in a position upstream of the screen SC after having passed through the projection optical system40, and the plane at the intersection is a projection rear focal plane FC′ or the screen SC1set on the downstream side or in a position downstream of the projection optical system40, as shown inFIG. 3(A).

FIG. 4(A)shows a case where an image is projected on a screen SC2or a projection receiving object disposed in a position relatively distant from the projector2, andFIG. 4(B)shows the image source areas AS set in the display sections21or the liquid crystal panels21a. In the distant-range projection, the image source areas AS in the liquid crystal panels21aarranged in a matrix are so disposed that the image source area AS in a liquid crystal panel21acloser to the periphery is shifted inward by a greater amount, as shown inFIG. 4(B). More specifically, each of the image source areas AS is shifted toward the optical axis OA with reference to the standard position corresponding to the divided optical axis OA1shown inFIG. 2(A). Further, the amount of shift described above increases in proportion to the distance from the optical axis OA to the liquid crystal panel21a. As a result, since the image light rays IM0, IM1, and IM2intersect the optical axis OA in a position downstream of the conjugate position PC, they intersect the optical axis OA also in a position downstream of the screen SC after having passed through the projection optical system40, and the plane at the intersection is the projection rear focal plane FC′ or the screen SC2, as shown inFIG. 4(A).

As described above, adjusting the arrangement of the image source areas AS set in the liquid crystal panels21aallows not only formation of image light rays IM each having an optical intensity distribution but also control of the exiting angle of each of the image light rays IM. The small image G1having desired luminance and color distributions can therefore be formed in a desired position upstream or downstream of the conjugate position PC along the optical axis OA. The position where the small image G1is formed corresponds to the position where the image light rays IM0, IM1, and IM2are superimposed on one another, and the projection front focal plane FC is present in the position. When the position of the projection front focal plane (superimposition position) FC is changed to a position upstream or downstream of the conjugate position PC, the two-dimensional arrangement pattern of the image source areas AS set in the plurality of liquid crystal panels21aarranged in a matrix is changed to a lattice-point-like pattern enlarged or reduced in a mathematically similar manner with reference to the lattice-point-like arrangement corresponding to the standard positions shown inFIG. 2(B)in such a way that the center of the pattern, through which the optical axis OA passes, remains unchanged.

FIGS. 5(A) and 5(B)are a front view and a side view showing an example of the projection receiving object, andFIG. 5(C)describes a specific example of the image source area AS set in one of the liquid crystal panels21a.

A projection receiving object PO shown inFIGS. 5(A) and 5(B)has a hemispherical shape, and the center thereof protrudes toward the projector2. A description will be made of a case where the surface of the projection receiving object PO is divided into areas AR11, AR12, AR13, and AR14sandwiched between contours based on the distance from the projector2. An image is projected over each of the areas AR11to AR14assuming that they are equidistant areas.

A description has been made of the display operation of the upper-right-corner display section121, and the other display sections21perform display operation similar to that of the display section121except that the image source areas AS11to AS14are located in different positions in the liquid crystal panel21a. It is, however, noted that the contours of the image ranges G11to G14and images displayed therein slightly differ from those in different display sections21.

A description will be made of shift of the focal position or the focus position of the projector2and the arrangement and display action of the image source areas AS set in the display sections21to achieve shift of the focal position with reference toFIGS. 6(A) to 6(C).

Consider a case where a virtual screen SC located in a basic position is provided and focus is achieved at a specific point IP0on the screen SC (case1) and a case where focus is achieved in a position upstream of the screen SC in the basic position by a distance A (case2), as shown inFIG. 6(A). In the case2, where focus is achieved in a position upstream of the screen SC, consider the following two points as the location where an image is displayed: a first point IP1on the optical axis OA; and a second point IP2, which deviates from the optical axis OA in the vertical direction.

As conceptually shown inFIG. 6(B), let C be the distance from the projection optical system40to the conjugate position PC, and F_pj be the focal length of the projection optical system40, the following relationship is satisfied based on a general lens expression.
1/C+1/B=1/F_pj

As conceptually shown inFIG. 6(C), in a case where the display device20itself shifts the focus from the screen SC forward by the distance A, let B′ be the distance between the first point IP1and the projection optical system40, and C′ be the distance between the projection optical system40and an intersection IP3corresponding to the first point IP1, the following relationship is satisfied based on the general lens expression.
1/C′+1/B′=1/F_pj

That is, to shift the focus forward from the screen position by the distance A, the following expression is satisfied, and the distance D from the conjugate position PC to the target projection front focal plane FC or the intersection IP3can be determined based on the focal length F_pj of the projection optical system40, the distance A, and other parameters.
1/(C+D)+1/(B−A)=1/F_pj

The distance D corresponds to the amount of focus shift of an intermediate image formed in a position upstream of the projection optical system40(corresponding to the small image G1shown inFIG. 1). That is, adjustment operation of changing the amount of focus shift of the intermediate image in a position upstream or downstream of the conjugate position PC allows adjustment of the focus position of an image projected by the projection optical system40to a position upstream or downstream of the basic position. Specifically, the image formation position can be shifted from the specific point (projected position) IP0on the screen SC to the first point (projected position) IP1.

Consider a condition under which the position of the intermediate image or the small image G1shown inFIG. 1(superimposition position or focus position) is changed on the the side of lens33, specifically, a condition under which an image (center image) is formed at the intersection IP3described above on the optical axis OA, with reference toFIG. 7(A). The intersection IP3is conjugate with the first point IP1shown inFIG. 6(A)with respect to the projection optical system40. First, let E be the distance between the superimposing lens33and the conjugate position PC, and consider an image light ray IM that exits out of a specific liquid crystal panel21aof the display device20toward the intersection IP3. To allow the image light ray IM to be incident not on the conjugate position PC but on the intersection IP3, which is upstream of the conjugate position PC, the exit position of the image light ray IM is shifted from the standard position on the divided optical axis OA1in a direction away from the optical axis OA. Let G be the amount of deviation in this case by which the exit position of the image light ray IM deviates from the optical axis OA, which is a general reference. The amount of deviation of the exit position of the image light ray IM in the liquid crystal panel21ain accordance with the change in the focus position or the superimposition position corresponds to the amount of deviation of the image light ray IM from the optical axis OA in the conjugate position PC. The amount of deviation H in the conjugate position PC that corresponds to the amount of deviation H0, by which the exit position of the image light ray IM is shifted from the divided optical axis OA1in the liquid crystal panel21a, is determined as follows.
H:D=G:(E−D)
H=D×G/(E−D)  (1)

That is, in the case of the image at the intersection IP3(center image), the amount of deviation H or the amount of deviation H0increases in proportion to the distance G from the optical axis OA to the exit position of the image light ray IM.

A description will then be made of a condition under which an image is formed at an off-axis point IP4(peripheral image), which deviates from the intersection IP3in the direction perpendicular to the optical axis OA, with reference toFIG. 7(B). The off-axis point IP4corresponds to the second point IP2inFIG. 6(A). In this case, the amount of deviation of the image light ray IM from the optical axis OA in the conjugate position PC is the sum of the distance I from the optical axis OA to the off-axis point IP4and the amount of deviation H′ resulting from the angle of the image light ray IM. It is, however, noted that in the case of the off-axis point IP4, the determination of the amount of deviation of the exit position of the image light ray IM from the original position before the change in the focus position or the superimposition position in the liquid crystal panel21aonly needs to be made based on the amount of deviation H′. Let G′ be the amount of deviation of the exit position from the optical axis OA of the image light ray IM from the optical axis OA, and J be the amount of deviation added because the image under question is a peripheral image, the amount of deviation H′ in the conjugate position PC that corresponds to the amount of deviation H0′, by which the exit position of the image light ray IM is shifted from the original position in the liquid crystal panel21a, is therefore determined as follows.

That is, the amount of deviation H′ corresponding to the off-axis point IP4, which deviates from the optical axis OA, in the conjugate position PC slightly differs from the amount of deviation H corresponding to the intersection IP3on the optical axis OA, and the amount of deviation H0and the amount of deviation H0′ also slightly differ from each other.

The above discussion shows that the amount of image position deviation H0set in the liquid crystal panel21ato form an image at the intersection IP3on the optical axis OA and the amount of image position deviation H0′ set in the liquid crystal panel21ato form an image at the off-axis point IP4, which deviates from the optical axis OA, need to differ from each other in accordance with the position of the intermediate image or the small image G1shown inFIG. 1. That is, images displayed in the image source area AS in each of the liquid crystal panels21abefore and after a change in the focus position (superimposition position) slightly differ from each other. As a result, an image displayed in the image source area AS in each of the liquid crystal panels21ais a basic image deformed or distorted in advance in consideration of deformation in accordance with the focus position (superimposition position). Further, an image displayed in the image source area AS in each of the liquid crystal panels21aneeds to undergo deformation, shift, and other changes in accordance with the degree of deviation of the liquid crystal panel21afrom the optical axis OA.

In an actual projector, the behavior of an image light ray IM is checked in advance in a simulation, and the calculation described above is therefore not always required. The amount of deformation and the amount of shift between images displayed in the image source area AS in each of the liquid crystal panels21abefore and after a change in the focus position can be stored in the form of a conversion data table, and simple image conversion allows generation of a sharp, distortion-free image according to the focus position, which can then be projected on a target object or a projection receiving object.

Referring back toFIG. 1, the circuit apparatus80includes an image processor81, to which image data is externally inputted, a display driver82, which drives the display device20provided in the optical system unit50based on an output from the image processor81, and a main controller88, which oversees and controls the operation of the image processor81and the display driver82. The image processor81and the main controller88function as a display controller80a, which controls the operation of the display device20.

The image processor81forms an image signal that operates each of the liquid crystal panels21a, which form the display device20, based on the external image data. The external image data can contain, for example, an image content for each projection distance from the projector2. In this case, to perform projection according to the shape of the surface of a projection receiving object, information on images to be projected in areas separate from the projector2by a plurality of stepwise projection distances (distance zones) is read to produce signals carrying images to be formed in each of the liquid crystal panels21a. Specifically, the image processor81can calculate the image source area AS to be set in the each of the liquid crystal panels21ain such a way that a focused state is achieved in an area separate from the projector2by a target projection distance (distance zone). After the image processor81calculates an image to be displayed in the image source area AS in each of the liquid crystal panels21a, the projector2can superimpose the images formed in the image source areas AS in the liquid crystal panels21aon one another in the target projection distance area with no deviation between the images to project a bright, sharp image. An image formed in each of the image source areas AS is not congruent with a basic image as described above, but the basic image is deformed in accordance with the deviation in the position of the liquid crystal panel21afrom the center of the display device20, through which the optical axis OA passes, the magnitude of change in the focus position, and other factors. The image processor81deforms or corrects the image in accordance with the position of the liquid crystal panel21aand the change in the focus position.

The display driver82can operate each of the liquid crystal panels21a, which form the display device20, based on each of the image signals outputted from the image processor81to form a corresponding image in the liquid crystal panel21a.

An example of the operation of the projector2according to the present embodiment will be described below with reference toFIG. 8. The circuit apparatus80first externally acquires distance image data under the control of the main controller88(step S11). The distance image data is image data containing stereoscopic information and contains distance zone information and image information. The distance zone information contains a plurality of distance zones that correspond to or belong to ranges obtained by dividing the projection distance from the projector2into a plurality of stepwise segments, and the image information contains image data to be displayed in each of the distance zones. Specifically, each of the distance zones is similar to the area between a pair of contours adjacent to each other, and the image data specifies an image to be displayed in the area between the pair of contours adjacent to each other on a distance zone basis (see image source areas AS11to AS14, image ranges G11to G14, and other portions inFIG. 5(C)as specific example). That is, image data to be projected in a plurality of focus positions represented by the distance zones are provided in advance.

The main controller88then sets a projection distance zone based on the distance image data (step S12). That is, the main controller88selects a distance zone involved in the current projection from the plurality of distance zones described above and sets the selected distance zone as the projection distance zone.

The main controller88then selects image information or image data corresponding to the projection distance zone obtained in step S12as an image to be displayed (step S13).

Thereafter, in each of the liquid crystal panels21a, an image source area AS in which an image is displayed (seeFIGS. 2(A), 3(B), and4(B), for example) is set (step S14). The image source area AS is calculated by the image processor81and other components based on the projection distance zone obtained in step S12.

Thereafter, for each of the image source areas AS calculated in step S14, the image processor81corrects the image data selected in step S13(step S15). The reason for this is that correction of an image to be formed in each of the image source areas AS based on the degree of deviation of the liquid crystal panel21afrom the optical axis OA allows image light rays IM to be precisely superimposed on one another, whereby a sharp small image G1can be produced, as described with reference toFIGS. 7(A) and 7(B).

The image processor81then outputs the corrected image signal to the display driver82(step S16). The display driver82drives each of the liquid crystal panels21a, which form the display device20, to cause the liquid crystal panel21ato display an image corresponding to the image signal inputted from the image processor81.

The main controller88then evaluates whether or not there is any left distance zone to be involved in the following projection among the plurality of distance zones obtained in step S11(step S17). When there is a left distance zone to be involved in the following projection, the control returns to step S12, where a distance zone to be involved in the current projection after the update is selected.

When no distance zone is left in step S17, it is evaluated whether or not there is a next frame (step S18). No left distance zone means that one image has been completely projected. That is, repeating steps S12to S17allows projection of images in a time division manner in the entire projection distance zones, which form a three-dimensional range. On the other hand, when the result of the evaluation in step S18shows that a next frame is present, the control returns to step S11, where distance image data corresponding to the next frame is acquired.

When frames change in a time series manner and they change at high speed, motion images are displayed in the image source areas AS, whereby stereoscopic motion images are projected on the surface of a stereoscopic projection receiving object.

In the processes described above, it is assumed that the distance and orientation from the projector2to a projection receiving object are known, and that the shape of the projection receiving object is also known. The same projection can, however, be performed even when the distance and orientation to a projection receiving object are unknown. In this case, providing the projector2with a distance measurement apparatus and an image recognition apparatus and measuring the distance and orientation from the projector2to a projection receiving object allow the same projection operation shown inFIG. 8. Further, even when the shape of a projection receiving object is unknown or changes, measuring or otherwise identifying the shape of the projection receiving object allows the same projection. In this case, distance image data is partially prepared or processed in the projector2.

According to the projector2of the present embodiment described above, the projection optical system40projects a superimposed image from the superimposing optical system30, and the display controller80achanges the position where image light rays IM are superimposed on one another to a plurality of superimposition positions different from one another along the optical axis OA, whereby simultaneous or concurrent projection in spaces having different depth ranges can be performed.

Second Embodiment

A projector according to a second embodiment will be described below. The projector according to the second embodiment is a deformed version of the projector according to the first embodiment, and portions that will not be particularly described below have the same structures as those in the projector according to the first embodiment.

The projector2according to the second embodiment is provided with a parallelized light selection section (light ray selection section)25in a display device120, as shown inFIG. 9. The parallelized light selection section25has a pair of lens arrays26and27, which have the same structure as that of the lens array31in the superimposing optical system30and are disposed to be concentric with each other, and a pinhole array28, which is aligned with the lens arrays26and27and disposed therebetween. Image light rays having exited out of the display sections21pass through lens elements26aof the lens array26, which cause the image light rays to converge, and the convergent image light rays pass through pinholes28aof the pinhole array28, which are located on the divided optical axes. The image light rays then pass through lens elements27aof the lens array27, which parallelize, that is, collimate the image light rays, and the parallelized or collimated image light rays are incident on the lens elements31aof the lens array31. Providing the parallelized light selection section25allows removal of unnecessary light resulting from diffracted light or other types of undesired light produced by the liquid crystal panels21a.

The light source used as the illuminator10is not limited to a surface-emitting laser, and the illuminator10can be formed, for example, of a lamp, a mirror, and a collimator lens.

Third Embodiment

A projector according to a third embodiment will be described below. The projector according to the third embodiment is a deformed version of the projector according to the first embodiment, and portions that will not be particularly described below have the same structures as those in the projector according to the first embodiment.

In the projector2according to the third embodiment, the optical system unit50includes image formation sections51R,51G, and51B for red, green, and blue components, and a cross dichroic prism55, and the projection optical system40, as shown inFIG. 10.

The image formation sections51R,51G, and51B for the color components have the same function as that of the illuminator10, the display device20, and the superimposing optical system30shown inFIG. 1but include illuminators10, display devices20, and superimposing optical systems30that provide different display colors.

The cross dichroic prism55is a light combining prism and combines image light rays formed by the image formation sections51R,51G, and51B to form image light and causes the image light to be incident on the projection optical system40.

The projection optical system40can enlarge and project the image light that is a combination of the image light rays modulated by the image formation sections51R,51G, and51B and combined with one another by the cross dichroic prism55on a stereoscopic object that is not shown.

The invention is not limited to the embodiments described above or examples thereof and can be implemented in a variety of aspects to the extent that they do not depart from the substance of the invention.

For example, the display device20can instead be formed of a single liquid crystal panel421a, as shown inFIG. 11. In this case, a large number of two-dimensionally arranged display sections21are provided in the liquid crystal panel421a.

The contour of each of the display sections21in the display device20and the method for arranging the display sections21are not limited to a rectangular or square shape or the method for arranging the rectangular or square areas in a matrix and can be changed in a variety of manners. The display sections21can be arranged, for example, in a triangular lattice point pattern, a hexagonal lattice point pattern, or any other lattice point pattern, and the contour of each of the display sections21can instead be a polygon, circle, or any other shape. In this case, light blocking frames21bare arranged in correspondence with the arrangement of the display sections21.

Further, the display sections21are not necessarily arranged in a closely packed manner and can instead be disposed at arbitrary two-dimensional points. In this case as well, the light blocking frames21bare arranged in correspondence with the arrangement of the display sections21.

It can be said that the display sections21, which form the display device20, allow projection based on superimposition of light fluxes from at least two display sections21. However, from a viewpoint of projection of a bright image, the display sections21are desirably arranged, for example, in a matrix of 5 rows and 5 columns or a larger number of rows and columns.

Further, the display elements provided in the display device20are not limited to the transmissive liquid crystal panels21aand can instead be reflective liquid crystal panels. In this case, the reflective liquid crystal panels in a single row are illuminated together, and the reflective liquid crystal panels illuminated on a row basis are arranged in a plurality of rows to achieve a two-dimensional arrangement of the reflective liquid crystal panels.

Further, each of the display elements provided in the display device20can instead be a digital micromirror device that uses a micromirror as a pixel or any of a variety of other types of light modulation device.

Moreover, the projection optical system40may instead be a zoom lens. In this case, reduction projection can be performed, and a variable depth of field can be achieved. Adjusting the depth of field of the projection optical system40allows the display range in the depth direction to be widened. Further, a variable focused state of the projection optical system40allows the three-dimensional projection space provided by the projector2to be shifted along the optical axis OA.

REFERENCE SIGNS LIST