JP2006317818A - Projection type video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type video display device which hardly causes color mixing of a color bar scanning on a video display element and has a bright scanning system. <P>SOLUTION: A means which separates light flux radiated from a light source into plural colors of light is constituted as follows: a plurality of dichroic mirrors which transmit color light beams having wavelength regions different from one another are arranged on an emission surface of the means; total reflection mirrors which reflect white light are arranged on boundaries between the plurality of dichroic mirrors; incident opening parts having optical opened holes, through which incident light beams on a color separation means is made incident, are arranged on the incident surface of the color separation means; and second reflection mirrors which again reflect the light beams reflected by the dichroic mirrors or the total reflection mirrors are arranged on the outer side of the incident opening parts. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection apparatus that projects an image on a screen using an image display element, for example, an optical unit such as a liquid crystal projector apparatus, a reflective image display projector apparatus, a projection type rear projection television, or a projection type image display. The present invention relates to an apparatus, and relates to a technique for scanning color light separated by a color separation unit on an image display element.

  Conventionally, after passing light from a white light source through an integrator means, a polarization beam splitter (PBS), and a collimator lens, strip-shaped (band-shaped) R light, B light and a plurality of dichroic mirrors are used. The light is separated into G light, and each separated color light is changed to an optical path by using a rotating polyhedron to irradiate different positions of the light valve at the same time. 2. Description of the Related Art A single-plate projection type image display apparatus is known that is moved in a certain direction on a valve (also referred to as “scanning” or “scroll”). This type of technology is described in, for example, Patent Document 1 and Patent Document 2.

  In the above-described scanning (scrolling) projection-type image display device, for example, as shown in FIG. 3 of Patent Document 1, the location of three strip-shaped irradiation areas corresponding to each color light formed on the light valve Is scrolled by the rotating polyhedron. However, in actuality, in order to allow the accuracy of component parts, variation during assembly, or due to the aberration of the optical system after color separation, there is an overlapping portion at the boundary of the strip-shaped irradiation area of each color light formed on the light valve Occurs, that is, color mixing occurs.

  Therefore, in order to reduce the color mixture that occurs at the boundary between the strip-shaped irradiation regions, a technique for displaying the image of the boundary portion where the strip-shaped irradiation regions overlap (color mixing) on the light valve is displayed in black is disclosed in, for example, Patent Document 3. Has been.

JP 2004-170549 A JP 2003-255250 A JP 2001-356287 A

  As described above, in Patent Document 3, color mixing is reduced by setting the image display of the boundary portion where the overlapping (color mixing) of the strip-shaped irradiation regions occurs as black display. However, for this purpose, a black display signal generation circuit and a timing control circuit for displaying black at the boundary are necessary, which causes a cost increase. In addition, when using an IC as a video signal processing circuit, IC development is required to apply the technique of Patent Document 3, and in addition, costs for IC integration (for example, mask costs) are also required. It becomes.

  The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide a projection display apparatus that can reduce the color mixture of overlapping portions of strip-shaped irradiation areas without using a circuit-like technique.

  In order to achieve the above object, the present invention is a projection-type image display device, comprising a white light source, an image display element that forms an optical image according to an image signal from light emitted from the white light source, and the white Color separation means for separating a light beam emitted from a light source into a plurality of color lights, scanning means for moving each of the plurality of color lights separated by the color separation means on the video display element, and emitted from the video display element Projection means for projecting the reflected light as a color image, and the color separation means includes a plurality of dichroic mirrors that transmit color lights in different wavelength ranges on the emission surface, and a boundary between each of the plurality of dichroic mirrors. A total reflection mirror is disposed on the surface, and an incident opening having an optical hole through which a light beam incident on the color separation unit is incident is disposed on the incident surface of the color separation unit. Outside To, be configured to dispose the second reflecting mirror again reflects the reflected light beam of the dichroic mirror or the total reflection mirror shells.

  ADVANTAGE OF THE INVENTION According to this invention, the projection type video display apparatus which can prevent color mixing can be provided.

  Hereinafter, the best mode of the present invention will be described with reference to the drawings. In each figure, elements having common functions are denoted by the same reference numerals, and description of elements once described is omitted.

  Hereinafter, a scanning projection type image display apparatus according to a first embodiment using a color prism as a color separation element and one rotating polyhedron will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of a scanning projection type image display apparatus showing a first embodiment, FIG. 2 is a diagram for explaining a mapping relationship in the first embodiment, and FIG. 3 is a light beam of a reduction optical system and an enlargement optical system. FIG. 4 is a diagram for explaining the scanning action in the first embodiment, and FIG. 5 is a schematic configuration diagram of the color separation unit in the first embodiment.

  First, the configuration of the scanning projection display device according to this embodiment will be described with reference to FIG. Here, in order to facilitate the following illustration, a right-handed rectangular coordinate system is introduced in FIG. That is, the optical axis direction of the light source unit 1 is the Z axis, the direction orthogonal to the paper surface of FIG. 1, the direction from the back of the paper surface to the paper surface is the Y axis, and the axis orthogonal to the YZ plane formed by the YZ axis is the X axis.

  In FIG. 1, the substantially white light beam emitted from the light source unit 1 including the light source 11 and the reflector 12 (in this figure, an elliptical reflector) is incident on the color separation unit 2 a disposed near the second focal position of the reflector 12. The light is focused and incident.

  The color separation unit 2 a includes a polarization conversion element 21 that aligns the polarization direction of the light beam from the light source unit 1 with a predetermined polarization direction, a light pipe 24 that is an integrator element whose cross-sectional area gradually increases in the emission side direction, and a light pipe 24. A color prism that is a color separation element that separates the light of 3 into different color lights (for example, R light, G light, and B light) of three strips (bands) arranged in the Y-axis direction (direction perpendicular to the paper surface of FIG. 1) 27 and a light-shielding frame 28 that shields light beams emitted from regions near the boundary between the three strip-shaped (band-shaped) color light regions formed by the color prism 27. The polarization conversion element 21 includes a polarization separation prism 211 and a half-wave plate 212. Hereinafter, strip-shaped (strip-shaped) colored light is referred to as a “color bar”.

  The light beam incident on the color separation unit 2 a is first aligned in a predetermined polarization direction (here, S-polarized light) by the polarization conversion element 21. In other words, the polarization separation prism 211 separates the light into P-polarized light and S-polarized light, and the polarization state is aligned with S-polarized light by one polarized light, in this figure, the half-wave plate 212 disposed on the exit surface of the P-polarized light. Next, the light flux aligned with the S-polarized light is repeatedly internally reflected by the light pipe 24, whereby the light quantity distribution is made uniform. In addition, since the cross-sectional shape of the light pipe 24 is gradually increased in the emission side direction, the F value of the emitted light is larger than the F value of the incident light, and the divergent component of the incident light can be reduced. Become. Finally, the white light whose polarization state is made uniform by the polarization conversion element 21 and whose light quantity distribution is made uniform by the light pipe 24 is three color lights (for example, R and R) arranged in the Y-axis direction by the color prism 27. G and B light) are separated and emitted. The configurations and functions of the color prism 27 and the light shielding frame 28 will be described later in detail with reference to FIG.

  The color bars of the three colored lights (polarized state is S-polarized light) separated by the color prism 27 are further purified via the reduction optical system 31 and the optical path bending mirror 32 by the polarizing plate 81 that transmits S-polarized light. Is improved and enters the first PBS 51. The S-polarized light beam (color bar) incident on the first PBS 51 is reflected by the polarization separation surface and travels toward the rotating polyhedron 4. The S-polarized light beam emitted from the first PBS 51 passes through the quarter-wave plate 82, is converted into circularly polarized light, and enters the rotating polyhedron 4 via the reduction optical system 33. In the process, the color bars of the three color lights formed on the exit surface of the color prism 27 are mapped onto the space before the rotating polyhedron 4 by the reduction optical systems 31 and 33 to form a spatial image (see FIG. 3). The

  The aerial image is reflected by the reflecting surface 41 on the surface of the rotating polyhedron 4 and turns back the optical path. By passing through the quarter-wave plate 82 again, the circularly polarized light is converted to P-polarized light, so that it passes through the first PBS 51 this time. The light beam transmitted through the first PBS 51 is converted into S-polarized light by the half-wave plate 83. Then, the S-polarized light beam incident on the second PBS 52 is reflected by the polarization separation surface and enters the video display element 6. In this process, the aerial image formed in the space in front of the rotating polyhedron 4 forms a specular image (not shown) on the reflecting surface 41 of the rotating polyhedron 4, and the specular image is formed by the magnifying optical system 33 (here, the light beam). Since the direction is reversed, it functions as a magnifying optical system) and is mapped onto the video display element 6.

  The light beam reflected by each pixel of the image display element 6 is converted into P-polarized light when each pixel is ON, so this time, it passes through the second PBS 52 and is screened by the projection lens 7 (not shown). The projection is enlarged. When each pixel is OFF, the polarization state remains S-polarized light, so that it is reflected again by the polarization plane of the second PBS 52, and the light beam is not enlarged and projected on a screen or the like. Reference numeral 84 denotes a polarizing plate that transmits P-polarized light.

  Next, the relationship among the color bars (objects) of the three color lights formed on the exit surface of the color prism 27, the aerial image, the specular image, and the mapping on the video display element 6 will be described with reference to FIGS. Will be described. FIG. 2 schematically shows the size of the object and the image viewed from the optical axis direction. 3A is a ray diagram from the exit surface of the color prism to the image display element, and FIG. 3B is an enlarged view of the vicinity of the reflecting surface of the rotating polyhedron.

  2 and 3, an image (reduced image) of the color bar (object) 200 formed on the exit surface of the color prism 27 is formed on the rotating polyhedron 4 by the reduction optical systems 31 and 33, the optical path bending mirror 32, and the first PBS 51. A space image 300 is formed in the front space. This is shown in the ray diagram of FIG. The mirror surface image 400 of the aerial image 300 is formed on the back side of the reflecting surface 41 by the reflecting surface 41 of the rotating polyhedron 4. However, since the reflecting surface 41 also rotates and the incident angle changes as the rotating polyhedron 4 rotates, the mirror surface image changes. 400 is moved (scanned) to become a scanning aerial image. Further, an enlarged image 600 of the scanning space image is formed on the video display element 6 by the magnifying optical system 33 (also used as a part of the reduction optical system) and the second PBS 52. Finally, the color image that has been modulated by the image display element 6 is enlarged and projected onto a projection surface such as a screen by a projection lens 7 as a projection device.

  Although the reduction optical system and the enlargement optical system have been described here, there is no problem in the mapping relationship even when the enlargement optical system and the reduction optical system are combined, but by using the combination of the reduction optical system and the enlargement optical system, a rotating polyhedron Since the aerial image formed in the vicinity of the four reflecting surfaces 41 can be reduced, there is an advantage that the rotating polyhedron 4 can be reduced.

  Next, the scanning action will be described with reference to FIG. FIG. 4A is an explanatory diagram of a specular image by the reflecting surface 41, and FIG. 4B schematically shows scanning of a color bar. When an object (aerial image) is placed in front of the reflection surface 41, a mirror image is formed on the back side of the reflection surface 41 at the same distance A from the reflection surface 41 to the object. By the way, since the reflecting surface 41 is disposed on the surface of the rotating polyhedron 4, the angle of the reflecting surface 41 is changed by the rotation of the rotating polyhedron 4. For example, when the reflecting surface 41 rotates by θ, the reflected light changes by 2θ by twice that amount. At this time, the reflected light overlaps with the emitted light as if from the intersection position between the line drawn by the dotted line in FIG. 4 and the specular image. Therefore, if the angle of the reflection surface 41 is continuously changed, continuous light rays are emitted from different positions of the specular image. That is, by changing the angle of the reflecting surface 41, light scanning (scrolling) can be realized as shown in FIG. The rotation angle described here is a rotation angle per one surface of the reflection surface 41 of the rotating polyhedron 4. For example, if the reflection surface 41 is 12 surfaces, 360 degrees / 12 = 30 degrees, and therefore the rotation angle is ± 15 degrees. The rotation angle of the entire rotating polyhedron 4 is repeated.

  Next, the configuration and function of the color prism 27 and the light shielding frame 28 will be described with reference to FIG.

  FIG. 5A is a YZ sectional configuration diagram showing the light pipe 24, the color prism 27, and the light shielding frame 28 extracted from the color separation unit 2a described in FIG. In FIG. 5A, the light beam incident on the light pipe 24 is uniformly reflected by the internal reflection by the light pipe 24, and is incident on the color prism 27. The color prism 27 is formed by laminating dichroic prisms elongated in the X-axis direction in the Y-axis direction. The color prism 27 transmits a first dichroic surface 271 that transmits first color light and reflects other color light, and transmits second color light. The second dichroic surface 272 reflects the other color light, and the third dichroic surface 273 transmits the third color light and reflects the other color light. The white light uniformized by the light pipe 24 is separated from the first color light by the first dichroic surface 271. Next, the color light reflected by the first dichroic surface is separated from the second color light by the second dichroic surface 272. Furthermore, the third color light is separated from the color light reflected by the second dichroic surface by the third dichroic surface 273.

  The color bar thus color-separated is mapped onto the image display element 6 by the scanning action by the rotating polyhedron 4 and the reducing optical system and the enlarging optical system before and after the rotating polyhedron 4 as described above. .

  However, the reduction optical system and the enlargement optical system before and after the rotating polyhedron 4 cannot have aberrations. Accordingly, a part of the first color light image and a part of the second color light image overlap on the video display element 6. Similarly, a part of the image of the second color light and a part of the image of the third color light overlap on the video display element 6. Further, a part of the third color light image and a part of the first color light image overlap on the video display element 6. Note that the overlap of a part of the third color light image and the part of the first color light image refers to the overlap of the color light reflected by different reflecting surfaces 41 of the rotating polyhedron 4. Further, in FIG. 4, the scanning action is described by changing the angle of the reflecting surface of the rotating polyhedron 41, but the rotating polyhedron 4 naturally also changes the position (distance from the aerial image) where the light beam is reflected by the rotating action. Therefore, strictly speaking, since the mapping relationship is lost during the rotation operation, it is impossible for the color bars to overlap each other on the video display element 6 also in this respect.

  Therefore, in this embodiment, a light shielding frame 28 is provided on the emission side of the color prism 27. FIG. 5B shows the exit surface shape of the light shielding frame 28 as viewed from the Z-axis direction. As shown in FIG. 5B, the light shielding frame 28 is provided between the first color light 2001 and the second color light 2002 of the color bar 200 and between the second color light 2002 and the third color light 2003. A light-shielding portion having a predetermined width T2 for preventing overlap (color mixing) on the video display element 6 is provided. In addition, since an overlap (mixed color) occurs between the first color light 2001 and the third color light 2003 by scanning, both the outer side of the color bar of the first color light 2001 and the color bar of the third color light, A light-shielding portion (a dotted line range) having at least predetermined widths T1 and T3 is provided. T1, T2, and T3 satisfy the following expression (1).

T1 + T3 ≧ T2 (Equation 1)
However, T1, T3 ≧ 0
For example, if the sum of the width T1 and the width T3 is equal to or greater than the width T2, color mixing between the color bar of the first color light 2001 and the color bar of the third color light can be prevented, and for example, T1 = 0 and T1 ≧ T2 It is good. However, T1 = T3 ≧ T2 is preferable from the viewpoint of ease of manufacturing. In FIG. 5B, the outer shape of the color prism 27 is indicated by a dotted line.

  As described above, according to the present embodiment, even when an image on the surface of the image display element 6 of each color bar spreads due to aberration or the like, it is possible to prevent overlapping of each color.

  That is, according to the present embodiment, the black display signal generation circuit and the timing control circuit for displaying the image of the boundary portion where the overlapping (color mixing) of the strip-shaped irradiation areas required in Patent Document 3 is displayed. Since it is not necessary, there is no significant increase in cost, and no IC development is required, so that product development can be performed relatively easily in a short time.

  In the first embodiment described above, by providing a light-shielding portion between the first color light, the second color light, and the third color light of the color bar, video display of each color bar due to aberration or the like. Even if the image on the surface of the element 6 spreads, the overlapping of the respective colors is prevented. However, the light flux is shielded by the light shielding portion of the light shielding frame 28, and the amount of light decreases accordingly.

  This reduction in the amount of light occurs even in the case of Patent Document 3. In Patent Document 3, even if there is an overlap of each color light on the surface of the image display element 6 of the color bar, each pixel at the corresponding position is displayed in black (OFF). However, forcibly displaying black means that the light beam that has reached the image display element 6 cannot be emitted from the projection lens 7, and the amount of light decreases accordingly.

  Hereinafter, a second embodiment for reducing the light amount reduction while reducing the color mixture will be described with reference to FIGS.

  FIG. 6 is a schematic configuration diagram of a color separation unit according to the second embodiment, and FIG. 7 is a schematic configuration diagram of a scanning projection type image display apparatus according to the second embodiment. As is apparent from FIG. 7, this embodiment uses a color separation unit 2b in place of the color separation unit 2a in the first embodiment.

  First, the configuration of the color separation unit in this embodiment will be described with reference to FIG. FIG. 6A is a sectional view of the color separation unit taken along the YZ plane, and FIG. 6B is a view showing an incident surface of the light pipe constituting the color separation unit.

  6A, the color separation unit 2b includes a polarization conversion element 21 that aligns the polarization direction of the light beam from the light source unit 1 with a predetermined polarization direction, and a light pipe that is an integrator element whose cross-sectional area gradually increases in the emission side direction. 24, and three different color lights (first color light 2001, second color light 2002, and third color light 2003) provided on the light pipe 24 emission side and arranged in the Y-axis direction from the light pipe 24. The dichroic mirror 25 is a color separation element that separates the color bars, and a total reflection mirror 26 that reflects white light provided between the dichroic mirrors 25.

  The dichroic mirror 25 transmits only the first color light and reflects the other color light, the dichroic mirror 251 that transmits only the second color light and reflects the other color light, and transmits only the third color light. The dichroic mirror 253 reflects other color light. The total reflection mirror 26 is disposed between the dichroic mirrors 251 and 252, between the dichroic mirrors 252 and 253, and on both outer sides of the dichroic mirrors 251 and 253. In the first embodiment, the color mixture is reduced by the light shielding frame 28. However, in this embodiment, the total reflection mirror 26 is provided in a portion corresponding to the light shielding portion of the light shielding frame 28 to reduce the color mixture.

  Further, an incident plate 23 having an incident aperture 231 with an optical hole and a total reflection mirror 232 provided corresponding to a region other than the incident aperture 232 is disposed on the incident side of the light pipe 24. . The total reflection mirror 232 reflects the light beam reflected by the dichroic mirrors 251, 252, 253 and the total reflection mirror 26 again to the light pipe 24 emission side.

  Next, the function of this embodiment will be described with reference to FIG. Since FIG. 7 is the same as the above-described scanning projection type video display apparatus of FIG. 1 except for the color separation unit, the overlapping description is omitted.

  In FIG. 7, the white light beam emitted from the light source unit 1 is incident on the incident opening 231 of the incident plate 23 of the color separation unit 2b. The incident light flux is subjected to internal reflection by the light pipe 24 to make the light quantity distribution uniform. Of the uniformed white light beam, the first color light 2001 reaching the first dichroic mirror 251 is emitted from the first dichroic mirror 251 as part of the color bar. Similarly, the second color light 2002 reaching the second dichroic mirror 252 out of the uniformed white light beam is emitted from the second dichroic mirror 252 as part of the color bar. Similarly, of the uniformed white light beam, the third color light 2003 that reaches the third dichroic mirror 253 is emitted from the third dichroic mirror 253 as part of the color bar.

  Other than the above combinations, for example, the second color light and the third color light that reach the first dichroic mirror 251 out of the uniformed white light beam are reflected by the first dichroic mirror 251, and the light pipe 24. Return to the incident side. Similarly, the first color light and the third color light that have reached the second dichroic mirror 252 out of the uniformed white light beam are reflected by the second dichroic mirror 252 and enter the incident side of the light pipe 24. Return. Similarly, the first color light and the second color light that reach the third dichroic mirror 253 out of the uniformed white light beam are reflected by the third dichroic mirror 253 and return to the incident side of the light pipe 24. .

  Further, the first color light, the second color light, and the third color light that have reached the total reflection mirror 26 out of the uniformed white light beam are also reflected by the total reflection mirror 26 and are incident on the incident side of the light pipe 24. Return.

  Of the light flux returned to the incident side, a part of the light flux passes through the incident aperture 231 and returns to the light source unit 1 side, but most of the light flux is totally reflected corresponding to a region other than the incident aperture. The light is reflected by the mirror 232 and reaches the exit surface of the light pipe 24 again. Hereinafter, this is repeated.

  The reason why most of the light beam is reflected again by the total reflection mirror 232 of the incident plate 23 is that the light distribution is already made uniform on the emission side of the light pipe 24, so that it is reflected and reflected by the incident plate 23. This is because the light flux that has reached 1 is also made uniform and is reflected at the area ratio of the incident aperture 231 and the total reflection mirror 232.

  As described above, the color separation unit 2b according to the present embodiment suppresses the deterioration of the light amount by recycling the light at the boundary of each color light, and prevents the color mixture by providing the light shielding between the color bars.

  In this embodiment, as shown in FIG. 6B, two incident openings 231 are provided. This is because the polarization conversion element 21 is provided on the incident side of the color separation unit 2a shown in FIG. This is because it is provided. Natural light (white light) incident on the polarization conversion element 21 is separated into P-polarized light and S-polarized light. In this embodiment, a half-wave plate 212 is arranged on the exit surface of the P-polarized light and is aligned with S-polarized light. .

  In the above description, the total reflection mirror 26 is provided not only between the dichroic mirrors 251 and 252 and between the dichroic mirrors 252 and 253, but also on both outer sides of the dichroic mirrors 251 and 253. It is not limited to. The total reflection mirrors on both outer sides of the dichroic mirrors 251 and 253 are for preventing color mixing of the color bar of the first color light and the color bar of the third color light caused by scanning. Either the dichroic mirror 251 or the dichroic mirror 253 is used. Alternatively, a total reflection mirror having a predetermined width may be provided outside one of them. In order to prevent color mixing of the color bar of the first color light and the color bar of the third color light, the width of the color bar of the first color light and the width of the color bar of the third color light may be reduced. In this case, the width (Y-axis direction) of the dichroic mirrors 251 and 253 may be reduced, the outer total reflection mirrors on both sides may be omitted, and the inner diameter of the color separation unit in the Y-axis direction may be reduced accordingly. .

  Of course, it goes without saying that the light shielding frame of the first embodiment and the total reflection mirror of this embodiment may be used in appropriate combination.

  The color separation unit 2c in the third embodiment will be described with reference to FIG.

  The difference from the second embodiment shown in FIG. 6 is the position of the polarization conversion element 21. In this embodiment, the polarization conversion element 21 is disposed between the incident plate 23 and the dichroic mirrors 251, 252, and 253 on the exit side. It is that. Therefore, there is one incident aperture 231. Other operations and effects are the same as those in the second embodiment.

  Further, as is common in the second embodiment and the present embodiment, the total reflection mirror 26 provided on the emission side of the color separation unit 2c may be formed by vapor deposition or may be formed by a metal mirror.

  In addition, when the dichroic mirrors 251, 252, and 253 for each color light are vapor-deposited on a single glass, since the respective colors are directly adjacent to each other, the vapor deposition range must be strictly controlled. Therefore, when the dichroic mirrors 251 252 253 for the respective colors are vapor-deposited on the total reflection mirror 26, the vapor deposition range of the dichroic mirrors 251 252, 253 for each color light does not need to be set strictly. was gotten. That is, the total reflection mirror 26 is also deposited between the dichroic films of the respective colors later or first.

  The total reflection mirror 26 can obtain the above-described effect by arranging a metal mirror as a separate body instead of vapor deposition.

It is a schematic block diagram of the scanning projection type display apparatus which shows a 1st Example. It is a figure explaining the mapping relationship in a 1st Example. FIG. 3 is a ray diagram of a reduction optical system and an enlargement optical system in the first example. It is a figure explaining the scanning action of the rotation polyhedron in the 1st example. It is a schematic block diagram of the color separation unit in a 1st Example. It is a figure explaining the color separation unit in a 2nd Example. It is a schematic block diagram of the scanning projection type video display apparatus which shows a 2nd Example. It is a figure explaining the color separation unit in a 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source unit, 11 ... Light source, 12 ... Reflector, 2a, 2b, 2c ... Color separation unit, 21 ... Polarization conversion element, 211 ... Polarization separation prism, 212 ... 1/2 wavelength plate, 23 ... Incident plate, 231 ... Entrance aperture, 232... Total reflection mirror, 24. Light pipe, 25, 251, 252, 253 ... Dichroic mirror, 26 ... Total reflection mirror, 27 ... Color prism, 28 ... Shading frame, 31, 33 ... Reduction optical system, 32 DESCRIPTION OF SYMBOLS ... Optical path bending mirror, 33 ... Magnification optical system (used by common optical path), 4 ... Rotating polyhedron, 51 ... First PBS, 52 ... Second PBS, 6 ... Video display element, 7 ... Projection lens, 81 ... Polarizing plate, 82 ... 1/4 wavelength plate, 83 ... 1/2 wavelength plate, 84 ... polarizing plate.

Claims (5)

A white light source,
An image display element that forms an optical image according to an image signal from the light emitted from the white light source;
Color separation means for separating a light beam emitted from the white light source into a plurality of color lights;
Scanning means for moving each of the plurality of color lights separated by the color separation means on the video display element;
Projecting means for projecting light emitted from the image display element as a color image;
The color separation means includes
A plurality of dichroic mirrors that transmit colored light in different wavelength ranges are arranged on the emission surface,
Arranging a total reflection mirror at the boundary of each of the plurality of dichroic mirrors,
An incident opening having an optical hole through which a light beam incident on the color separation unit is incident is disposed on the incident surface of the color separation unit.
2. A projection type image display apparatus comprising: a second reflection mirror that reflects the reflected light beam of the dichroic mirror or the total reflection mirror shell again outside an incident opening of the incident surface.   The projection display apparatus according to claim 1, wherein a polarization conversion element is provided between the incident surface of the color separation unit and the white light source.   The projection type image display apparatus according to claim 1, wherein the color separation means includes a polarization conversion element between an incident surface and an output surface. The scanning means includes
A reduction optical system for forming a spatial image of light of each of the plurality of colors emitted from the emission surface of the color separation means;
A rotating polyhedron that forms a scanning aerial image by changing the angle of a mirror disposed in the vicinity of the aerial image;
An enlarged optical system for forming an enlarged image of the scanning space image on the image display element;
The projection type image display device according to claim 1, wherein the projection type image display device is configured as described above. 5. The projection type image display apparatus according to claim 4, wherein the reduction optical system and the enlargement optical system are configured to share a part of each optical path.

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