JP4806912B2 - Image projection device - Google Patents

Description

  The present invention relates to an image projection apparatus (projector apparatus). In particular, the present invention relates to a projector apparatus using a liquid crystal panel or the like as an image display means. Specifically, the present invention relates to a reflection type image projection apparatus of a type that reflects and modulates light with an image display means such as a reflection type liquid crystal panel.

  As a projector device using a liquid crystal display device (liquid crystal panel) that modulates polarized light on an image display means and displays an image, the modulated light is transmitted through the liquid crystal panel, and the modulated light passes through the liquid crystal panel. There are known a transmissive projector device that is modulated, and a reflective projector device that irradiates a liquid crystal panel with modulated light and modulates the polarization axis when the irradiated modulated light is reflected by the liquid crystal panel. ing. The present invention particularly relates to the latter reflective projector apparatus.

  As a reflection type projector device, for example, the one described in JP-A-8-15794 is known. The reflection type projector apparatus described in Japanese Patent Laid-Open No. 8-15794 is intended to be small and thin while avoiding interference between an illumination system and an optical system as much as possible.

  FIG. 7 is a configuration diagram of an optical system of a reflection type projector apparatus using a reflection type liquid crystal panel (LCOS: Liquid Crystal Silicon) as an image display unit as a representative example of such a reflection type projector apparatus. The reflective projector apparatus illustrated in FIG. 7 has a lamp 201 that outputs white light, a collimator lens 202, and a fly-eye lens as a light source that provides three primary colors, that is, blue, green, and red. 203, 204, PS conversion means 205 that converts incident light, for example, P-polarized light into S-polarized light, a main condenser lens 206, a blue reflective dichroic mirror 207, and a green-red reflective dichroic mirror 208 And total reflection mirrors 209 and 210 and a green reflection dichroic mirror 211.

  The reflective projector device further includes a cross prism 224 and three polarization beam splitters (PBS) disposed around the cross prism 224, that is, a first polarization beam splitter (PBS) 218, a second PBS 219, 3 PBS 223. The reflection type projector device includes a projection lens 225 on the side facing the second PBS 219 with the cross prism 224 interposed therebetween. A condenser lens 212 is disposed on one surface side of the second PBS 219, and a green liquid crystal reflection panel 213 and a quarter wavelength plate 214 are disposed on the other surface. A condenser lens 215 is disposed on one surface side of the first PBS 218, and a red liquid crystal reflection panel 217 and a quarter-wave plate 216 are disposed on the other surface. A condenser lens 220 is disposed on one surface side of the third PBS 223, and a green liquid crystal reflection panel 222 and a quarter-wave plate 221 are disposed on the other surface.

  The light source outputs three primary color lights, that is, blue light, green light, and red light as follows. For the red light, white light output from the main condenser lens 206 is reflected by the green-red reflection dichroic mirror 208, reflected by the total reflection mirror 209, passes through the green reflection dichroic mirror 211, and enters the condenser lens 215. For the green light, the white light output from the main condenser lens 206 is reflected by the green-red reflection dichroic mirror 208, reflected by the total reflection mirror 209, reflected by the green reflection dichroic mirror 211, and enters the condenser lens 212. As for the blue light, white light output from the main condenser lens 206 is reflected by the blue reflection dichroic mirror 207, reflected by the total reflection mirror 210, and incident on the condenser lens 220.

  The green light incident on the condenser lens 212 is reflected by the second PBS 219, passes through the quarter-wave plate 214, enters the green liquid crystal reflecting panel 213, and, when modulated there, passes through the second PBS 219 and passes through the cross prism. The light is incident on 224 and projected from the projection lens 225 onto a screen (not shown) positioned in front of the projection lens 225. The red light incident on the condenser lens 215 is reflected by the first PBS 218, passes through the quarter-wave plate 216, enters the liquid crystal reflective panel 217 for red, and when modulated there, passes through the first PBS 218 and passes through the first prism 218. The light is incident on 224 and projected from the projection lens 225 onto a screen (not shown) positioned in front of the projection lens 225. The green light incident on the condenser lens 220 is reflected by the third PBS 223, passes through the quarter-wave plate 221 and enters the green liquid crystal reflection panel 222. When modulated there, the green light passes through the third PBS 223 and passes through the cross prism. The light is incident on 224 and projected from the projection lens 225 onto a screen (not shown) positioned in front of the projection lens 225.

As illustrated in Patent Document 1 (Japanese Patent Laid-Open No. Hei 8-15794), a light source that provides light of three primary colors can be disposed on the upper portion of the above configuration.
JP-A-8-15794

  The reflection type projector apparatus using the first polarizing beam splitter (PBS) 218, the second PBS 219, and the third PBS 223 encounters a problem that the F-number of the illumination optical system cannot be reduced and is insufficient in terms of brightness. Yes.

  Further, as illustrated in FIG. 5B, the polarization beam splitter (PBS) has high incident angle dependency, and when there is obliquely incident light, the transmittance is reduced and the contrast of the image projected from the projection lens 225 is lowered. I'm running into a problem. In order to improve this, there is a disadvantage that each part of the optical system is accurately arranged and fine positional adjustment is required.

  Furthermore, the polarizing beam splitter (PBS) is relatively large in size and heavy in weight. As a result, a limit has been encountered in reducing the size of the reflective projector apparatus.

  When a polarization beam splitter (PBS) is used, the optical system is complicated as a whole, and it is difficult to arrange optical components. And it is difficult to mount optical components.

  In the reflection type projector apparatus, lamps 201, a green liquid crystal reflection panel 213, a red liquid crystal reflection panel 217, a green liquid crystal reflection panel 222, and the like are arranged, and cooling measures (heat dissipation measures) are provided. However, if a large number of parts are accommodated in a narrow space, it is difficult to sufficiently take measures for heat dissipation or cooling.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image projection apparatus that overcomes the above-mentioned problems, is compact and lightweight, has excellent contrast, is capable of sufficient cooling measures, and is advantageous in terms of mounting.

According to the present invention,
A cross prism that combines the three primary colors of red, green, and blue incident from three incident surfaces and emits the light from the emission surface;
A projection lens that is arranged so that light from the exit surface of the cross prism can enter, and projects the light combined by the cross prism onto a screen;
From the position of the lower portion of the cross prism and the projection lens is disposed surface, the red, green, illuminating the three primary colors of blue respectively as the illumination light, and three light source provided separately,
The cross prism is disposed at a position corresponding to the three incident surfaces, and modulates the three primary color lights of red, green, and blue emitted from the three light sources in accordance with an image display signal. Three reflective image display units for display;
Three polarization beam filters having low wavelength dependency, transmitting the first polarized light, and reflecting the second polarized light having a polarization axis orthogonal to the first polarized light, each in the vertical direction Disposed between the light source and the reflective image display unit, facing the corresponding incident surface of the cross prism in the horizontal direction and arranged at an angle of 45 degrees with respect to the vertical direction; The corresponding primary color light emitted from the light source is transmitted and guided to the corresponding image display unit, and the three primary color modulated image light modulated according to the image display signal in the image display unit is reflected by the polarization beam filter. And disposed so as to be incident on the corresponding incident surface of the cross prism, transmits the first polarized light, and reflects the second polarized light having a polarization axis orthogonal to the first polarized light. Bias And beam filters,
With
The now flat row in a plane perpendicular to the four joint surfaces of the cross prism, and the three incident surfaces and straight intersect each to the cross prism was disposed a display plane of the image display unit,
An image projection apparatus characterized by the above is provided.

  Preferably, the primary color illumination light incident on the polarizing beam filter is set so that the plane of polarization is P-polarized with respect to the polarizing beam filter. Preferably, the polarizing beam filter is configured so that the S-polarized light with respect to the polarizing beam filter is reflected and the direction thereof is transmitted so as to transmit the P-polarized light.

  Preferably, when the image display unit displays 0% black, the image display unit does not modulate the incident primary color light, and the image display unit displays 100% corresponding primary color light. If so, the image display unit modulates the incident primary color light so that the plane of polarization rotates approximately 90 degrees.

  Preferably, between the cross prism and the polarizing beam filter, two primary color lights out of the three primary colors synthesized by reflecting light on the reflection surface of the cross prism are reflected on the reflection surface of the cross prism. On the other hand, a half-wave plate on which light is incident is arranged so as to be S-polarized light.

  More preferably, linearly polarizing means is disposed between the half-wave plate and the polarizing beam filter so as to be substantially parallel to the half-wave plate, and the transmission axis of the linearly polarizing means is set to the cross prism. The direction of the light is substantially P-polarized with respect to the reflecting surface.

  Preferably, linear polarization means is disposed so that the primary prism light combined by transmitting light to the reflecting surface of the cross prism is substantially parallel to the primary prism light incident surface of the cross prism, The transmission axis of the linearly polarizing means is substantially configured in the direction of P-polarized light with respect to the reflecting surface of the cross prism.

Preferably, the image projection apparatus includes a first cooling unit that cools the three light sources.

Preferably, the image projection apparatus includes a second cooling unit that cools the three reflective image display units.

  Preferably, each of the image display units has a reflection surface (display surface) facing downward. More preferably, the apparatus further includes light sources that respectively provide the three primary color lights incident on the image display units from the lower portions of the three optical systems through the polarization separation units.

  In the present invention, a polarization beam filter (PBF: Polarized Beam Filter) is used instead of the optical polarization beam splitter (PBS) as the polarization / deflection means. As illustrated in FIG. 5A, the PBF has less wavelength dependency and less incident angle dependency. By using PBF having such advantages, various effects listed below can be achieved.

  Compared with an image projection apparatus using a polarization beam splitter (PBS), the image projection apparatus of the present invention using a polarization beam filter (PBF) can reduce the F-number, and thus can increase brightness and improve contrast. Furthermore, the image projection apparatus of the present invention using PBF has a margin in the arrangement of optical components as compared with the image projection apparatus using PBS. Further, fine adjustment of the position of the optical component after assembling the optical system becomes unnecessary.

  When PBF is used, it is possible to adopt a configuration in which the number of times the PBF is transmitted is reduced by one as compared with the case where PBS is used. As a result, the image projection apparatus of the present invention using PBF can further increase the luminance and improve the contrast.

  The image projection apparatus of the present invention can orderly arrange an optical system and the like. Moreover, the cross prism and the three optical systems can be arranged on the same plane, and the dimension in the height direction can be reduced. Furthermore, the image projection apparatus of the present invention is easy to arrange and design and has high accommodation efficiency, so that it can be accommodated in a compact manner and can be reduced in size and weight. PBF is small and lightweight, and can be further reduced in size and weight.

  The image projection apparatus of the present invention is easy to take cooling measures and has a high cooling effect.

  The image projection apparatus of the present invention can be easily wired to an image display unit or the like, and is advantageous in terms of mounting.

  The image projection apparatus according to the present invention has a high flexibility in arrangement of the projection lens, and can easily mount a vertical shift mechanism of the projection lens.

  In the image projection apparatus of the present invention, dust or the like floating in the housing is difficult to touch the panel surface, the level of polarized light due to adhesion of dust is small, and display image quality is hardly degraded.

  In the image projection apparatus of the present invention, the imaging optical system including the image display unit is arranged in a compact manner, and the mechanical structural rigidity is easily improved. For this reason, pixel position misalignment or the like between the three image display units hardly occurs, and a high-quality image can be provided.

  A reflection type projector apparatus as an embodiment of an image projection apparatus (projector apparatus) according to the present invention will be described with reference to FIGS. 1A and 1B are perspective views of a projector device according to a first embodiment of the present invention. FIG. 2 is a diagram showing a configuration example of a light source applicable to the projector apparatus illustrated in FIGS. 1 (A) and 1 (B). FIG. 3 is a diagram illustrating an example of a partial configuration and a ray trajectory in the projector apparatus illustrated in FIGS. 1 (A) and 1 (B). FIG. 4 is a diagram showing an outline of the arrangement of optical systems around the cross prism arranged in the projector apparatus illustrated in FIGS. 1 (A) and 1 (B).

[Main components of the projector device]
1A and 1B, a projector device 100 has a cross prism 10 in the center of the illustration, and a projection lens 16 in front of it. The projector device 100 includes the following optical systems in a total of three directions, both sides of the cross prism 10 and the side facing the projection lens 16 with the cross prism 10 interposed therebetween. 1A and 1B, on the left side of the cross prism 10, a first liquid crystal reflection panel 1 as a first optical system, and a first polarizing beam filter (first PBF) 61 as a means for separating polarized light. The first linearly polarizing plate 11 and the first half-wave plate 21 are included. 1A and 1B, a second liquid crystal reflection panel 2 and a second polarizing beam filter (second PBF) 62 are provided as a second optical system on the side facing the projection lens 16 with the cross prism 10 interposed therebetween. And a second linearly polarizing plate 12. 1A and 1B, on the right side of the cross prism 10, as a third optical system, a third liquid crystal reflective panel 3, a third polarizing beam filter (third PBF) 63, and a third linearly polarizing plate 13 are provided. And a third half-wave plate 23.

  The second optical system is not provided with a second wave plate corresponding to the first and third half-wave plates 21 and 23. The reason is described. In the example illustrated in FIG. 4, when the three primary color lights are combined in the cross prism 10, blue light incident on the reflection surface 10 a in the cross prism 10 from the first optical system is illustrated in FIG. 4. The modulated light 71m and the red modulated light 73m incident on the reflecting surface 10b in the cross prism 10 from the third optical system are reflected by the reflecting surfaces 10a and 10b in the cross prism 10, whereby the optical path changes by 90 degrees. On the other hand, light incident on the cross prism 10 from the second optical system passes through the cross prism 10 without being reflected.

  In the cross prism 10, S-polarized light is suitable for reflection and P-polarized light is suitable for transmission as the characteristics of the reflecting surfaces 10a and 10b formed by a dichroic coating film or the like. Therefore, in the present embodiment, an exemplary polarization state is selected. In order to adjust the polarization state in this way, the first and third optical systems are provided with half-wave plates 21 and 23, and the second optical system must be provided with half-wave plates. Absent. In addition, it can select suitably about how 2 primary color light of 3 primary color lights is selected.

  The cross prism 10 and the projection lens 16 are disposed on substantially the same plane. The first PBF 61, the first linearly polarizing plate 11, the first half-wave plate 21, the second PBF 62, the second linearly polarizing plate 12, and the second optical system of the first optical system, The third PBF 63, the third linearly polarizing plate 13, and the third half-wave plate 23 of the two optical systems are disposed on substantially the same plane. As described above, the optical system constituting the projector apparatus 100 is disposed (arranged) on substantially the same plane with the cross prism 10 interposed therebetween.

  In addition to the optical system components (optical components) described above, projector device 100 according to the embodiment of the present invention emits three primary color lights, that is, blue (B) light, green (G) light, and red (R) light. Although it has three types of light sources 51-53 to output, the detail is mentioned later.

  The three liquid crystal reflection panels 1 to 3 as the image display unit of the image projection apparatus of the present invention are one of three primary color lights, that is, one of blue (B) light, green (G) light, and red (R) light. It works to modulate the color light image. The configurations of these liquid crystal reflecting panels 1 to 3 are substantially the same except that the half-wave plate is not provided in the second optical system, and any of these is blue (B) light, green Which of (G) light and red (R) light is subjected to image modulation can be arbitrarily determined. That is, it is possible to arbitrarily design which primary color light is to be modulated in the first liquid crystal reflective panel 1, the second liquid crystal reflective panel 2, and the third liquid crystal reflective panel 3. In the present embodiment, as an example, the first liquid crystal reflective panel 1 functions as a blue liquid crystal reflective panel that modulates blue light and the second liquid crystal reflective panel 2 modulates green light. A case where the third liquid crystal reflective panel 3 functions as a red liquid crystal reflective panel that modulates the image of red light will be described. Of course, for this purpose, an image signal processing device (not shown) modulates the blue liquid crystal reflective panel 1 with blue, the green liquid crystal reflective panel 2 modulates green, and the red liquid crystal reflective panel 3 has red. An image signal for modulating the signal is output according to the image display content. However, a detailed description of the image signal processing apparatus is omitted.

〔light source〕
The projector device 100 includes a blue illumination light source 51 that irradiates blue light 71 perpendicular to the surface of the blue liquid crystal reflective panel 1, and a green illumination light source 52 that radiates green light 72 orthogonal to the surface of the green liquid crystal reflective panel 2. And a red illumination light source 53 that irradiates red light 73 perpendicular to the surface of the red liquid crystal reflective panel 3. The blue illumination light source 51, the green illumination light source 52, and the red illumination light source 53 can have various configurations and arrangements. In the present embodiment, the configuration illustrated in FIG. 2 can be used. . However, in the image projection apparatus of the present invention, the light source is not an essential requirement, and can take various other forms besides those illustrated in FIG. Accordingly, the light source illustrated in FIG. 2 is merely exemplary.

  A light source 500 illustrated in FIG. 2 converts a lamp 501 that outputs white light, fly-eye integrators 502 and 503, and P-polarized light and S-polarized light into light of a predetermined polarization component. A PS conversion element 504 to output, a red reflecting dichroic mirror 506, a patina reflecting dichroic mirror 507, total reflection mirrors 508, 509, 512, 511 and 513, and condenser lenses 515 and 516 are provided.

  The white light emitted from the lamp 501 becomes illumination light made uniform by the fly-eye integrators 502 and 503, and the polarization direction is aligned by the PS conversion element 504. In this way, white light 520 that is illumination light whose polarization direction is uniformed in the PS conversion element 504 is condensed toward the liquid crystal reflection panels 1 to 3 by the main condenser lens 505. The white light 520 is separated by the red reflecting dichroic mirror 506 and the green-blue reflecting dichroic mirror 507, and blue, green, and red are separated. The red reflected light 521 reflected by the red reflecting dichroic mirror 506 is redirected (deflected) by the total reflection mirror 509, condensed by the condenser lens 516, and positioned above the light source 500 by the total reflection mirror 513. The red light 73 is reflected by being reflected toward the red liquid crystal reflective panel 3. The reflected light 522 having green and blue spectra reflected by the green-blue reflecting dichroic mirror 507 is redirected (deflected) by the total reflecting mirror 508 and reaches the green reflecting dichroic mirror 510. The green light is reflected in the direction of the total reflection mirror 511 by the green reflection dichroic mirror 510 and changed in direction (deflected), and the direction of the light source 500 is changed in the upward direction by the total reflection mirror 511. The light is condensed toward the green liquid crystal reflective panel 2 of the projector device 100 to become green light 72. The light reflected by the total reflection mirror 508 is collected by the condenser lens 515, collected by the total reflection mirror 512 toward the blue liquid crystal reflection panel 1 of the projector device 100, and becomes blue light 71.

  In the present specification and drawings, for convenience, in the light source 500 illustrated in FIG. 2, a portion that outputs blue light 71 is referred to as a blue illumination light source 51, and a portion that outputs green light 72 is referred to as a green illumination light source 52. The portion that outputs the red light 73 is called a red illumination light source 53, and is illustrated by a broken line in FIGS. 1 (A) and 1 (B).

  FIG. 3 is a cross-sectional view illustrating an enlarged positional relationship among the first liquid crystal reflective panel 1, the blue illumination light source 51, and the first PBF 61 disposed therebetween as a representative. As illustrated in FIG. 3, the illustrated projector device 100 is disposed between the blue illumination light source 51 and the blue liquid crystal reflective panel 1 in a state inclined by 45 degrees on the surface of the blue liquid crystal reflective panel 1. A first polarizing beam filter (first PBF) 61 is provided. The first PBF 61 is arranged in a state inclined by approximately 45 degrees with respect to the blue light 71 output from the blue illumination light source 51 and incident on the blue liquid crystal reflection panel 1 substantially orthogonally to the surface.

  Similarly, the projector device 100 includes a second polarizing beam filter (first lens) disposed between the green illumination light source 52 and the green liquid crystal reflective panel 2 so as to be inclined by 45 degrees on the surface of the green liquid crystal reflective panel 2. 2PBF) 62. The second PBF 62 is arranged in an inclined state of about 45 degrees with respect to the green light 72 output from the green illumination light source 52 and incident on the surface of the green liquid crystal reflective panel 2 substantially orthogonally. Similarly, the projector device 100 includes a third polarizing beam filter (which is disposed between the red illumination light source 53 and the red liquid crystal reflective panel 3 so as to be inclined by 45 degrees with respect to the surface of the red liquid crystal reflective panel 3). 3rd PBF) 63. The second PBF 62 is arranged in an inclined state of about 45 degrees with respect to the green light 72 output from the green illumination light source 52 and incident on the surface of the green liquid crystal reflective panel 2 substantially orthogonally.

[Blue ray locus]
3A and 3B, details of the relationship among the blue liquid crystal reflective panel 1, the blue illumination light source 51, and the first polarizing beam filter (first PBF) 61 will be described. The blue illumination light source 51 irradiates the blue light 71 orthogonal to the surface of the blue liquid crystal reflective panel 1 through the first PBF 61. In the present embodiment, the blue illumination light source 51 irradiates the blue light 71 from the lower part of the blue liquid crystal reflective panel 1 toward the blue liquid crystal reflective panel 1. The blue light 71 output from the blue illumination light source 51 passes through the first PBF 61 having the P polarization axis parallel to the paper surface and enters the blue liquid crystal reflection panel 1.
As illustrated in FIG. 3A, when the blue light 71 is not modulated in the blue liquid crystal reflective panel 1, the blue light 71 having the P polarization axis is reflected by the blue liquid crystal reflective panel 1 and remains as it is. The light enters the first PBF 61 again and returns to the blue illumination light source 51.
On the other hand, as illustrated in FIG. 3B, when the blue light 71 is modulated when reflected by the blue liquid crystal reflection panel 1, the blue light 71 having the P polarization axis parallel to the paper surface is perpendicular to the paper surface. The blue modulated light 71m having the S polarization axis enters the first PBF 61, is reflected by the first PBF 61 toward the cross prism 10, and passes through the first linear polarizing plate 11 and the first half-wave plate 21. Head to the cross prism 10. And since the reflective surface of 1st PBF61 which consists of transparent plate-shaped members, such as glass, is formed in the liquid crystal reflective panel 1 side for blue, and it is comprised so that the reflected light may be projected with the projection lens 16, it arrange | positions diagonally Aberrations that occur when light passes through the plate-shaped member thus made can be avoided, and a good projection image can be obtained.

  The blue illumination light source 51 adjusts the polarization axis in advance so as to output blue light 71 having the illustrated polarization axis (axis parallel to the drawing) so as to be P-polarized with respect to the first PBF 61. It has been broken. The direction of the first PBF 61 is set so as to transmit the P-polarized light with respect to the first PBF 61 and reflect the S-polarized light. Therefore, the blue light 71 emitted from the blue illumination light source 51 having the illustrated polarization axis passes through the first PBF 61 and enters the blue liquid crystal reflective panel 1.

  When the liquid crystal reflective panel 1 for blue, the liquid crystal reflective panel 2 for green, and the liquid crystal reflective panel 3 for red are displaying 0% black, the plane of polarization of the incident light is not rotated, and 100% blue, In the case of displaying red and green, the liquid crystal reflection panels 1 to 3 for each color are set to modulate the polarization plane so that the polarization plane of the incident light is rotated by approximately 90 degrees. Which color is displayed on the liquid crystal liquid crystal reflection panels 1 to 3 for each color is input to the liquid crystal reflection panels 1 to 3 for each color from an image signal processing device (not shown), for example. Depends on the image signal.

  As illustrated in FIG. 3A, when the blue liquid crystal reflective panel 1 displays 0% black, the blue light 71 passes through the first PBF 61 and enters the blue liquid crystal reflective panel 1. The light is reflected by the liquid crystal reflection panel 1, passes through the first PBF 61 again, and returns to the blue illumination light source 51 side.

  As illustrated in FIG. 3B, when the blue liquid crystal reflective panel 1 displays 100% blue, the blue light 71 passes through the first PBF 61 and enters the blue liquid crystal reflective panel 1 to reflect the blue liquid crystal. Since the polarization axis is rotated 90 degrees by the blue liquid crystal reflection panel 1 when reflected by the panel 1, the blue modulated light 71m having the P polarization axis is obtained, and the polarization axis of the blue modulated light 71m at that time is orthogonal to the paper surface. It becomes the S-axis, becomes S-polarized light with respect to the first PBF 61, is reflected by the first PBF 61, passes through the first linear polarizing plate 11, and travels in the direction of the cross prism 10 via the first half-wave plate 21. As described above, the blue modulated light 71m passes through the first linearly polarizing plate 11 and the first half-wave plate 21 disposed between the first PBF 61 and the prism 10 before entering the cross prism 10. pass. The polarization transmission axis of the first linearly polarizing plate 11 is set in substantially the same direction as the S-polarized light with respect to the first PBF 61, and the blue modulated light 71m can pass through the first linearly polarizing plate 11 as it is. The first half-wave plate 21 is set to have an angle of 45 degrees with respect to its polarization axis, and the polarization axis of the blue modulated light 71 m that has passed through the first half-wave plate 21. Is in the direction of S polarization with respect to the reflecting surface of the cross prism 10.

  As illustrated in FIG. 4, the reflecting surface 10 a of the cross prism 10 has a coating (coating) that reflects blue, and the blue modulated light 71 m is reflected by the reflecting surface 10 a, so that the projection lens 16 Then, the projection lens 16 projects (projects) it onto a screen (not shown) positioned in front of the projection lens 16.

[Red ray trajectory]
Next, the red ray trajectory (path) will be described. The red ray trajectory is basically the same as the blue ray trajectory. The red light 73 output from the red illumination light source 53 located below the red liquid crystal reflection panel 3 and the second polarizing beam filter (second PBF) 62 passes through the third PBF 63 and enters the red liquid crystal reflection panel 3. The polarization axis is adjusted in advance so that the red light 73 has a polarization axis that becomes P-polarized with respect to the third PBF 63. The direction of the third PBF 63 is set so as to transmit the P-polarization axis relative to the third PBF 63 and reflect the S-polarized light. .

  When the red liquid crystal reflective panel 3 displays 0% black, the red light 73 that has passed through the third PBF 63 and entered the red liquid crystal reflective panel 3 is reflected by the red liquid crystal reflective panel 3 as it is, and has a P polarization axis. While maintaining the above, the light passes through the third PBF 63 again and returns toward the red illumination light source 53 side.

  When the red liquid crystal reflective panel 3 displays 100% red, the red light 73 transmitted through the third PBF 63 and incident on the red liquid crystal reflective panel 3 is reflected by the red liquid crystal reflective panel 3 so that the polarization axis is The red modulated light 73m having the S polarization axis is rotated by 90 degrees. The red modulated light 73m has a polarization axis that becomes S-polarized light and becomes S-polarized light with respect to the third PBF 63. Therefore, the red modulated light 73m is reflected by the third PBF 63 and passes through the third linearly polarizing plate 13 and the third half-wave plate 23. It proceeds in the direction of the cross prism 10 via. As described above, the red modulated light 73m passes through the third linearly polarizing plate 13 and the third half-wave plate 23 disposed between the third PBF 63 and the cross prism 10 before entering the cross prism 10. pass. The polarization transmission axis of the third linear polarizing plate 13 is set in substantially the same direction as the S-polarized light with respect to the third PBF 63, and the red modulated light 73m can be transmitted as it is. The axis of the third half-wave plate 23 is set so as to form an angle of 45 degrees with respect to the polarization axis thereof, and the polarization axis of the red modulated light 73m passing through the third half-wave plate 23 is the reflection surface of the cross prism 10 The direction is S-polarized light. Further, the reflecting surface 10b of the prism 10 is provided with a coating (coat) that reflects red, and the red modulated light 73m is reflected by the reflecting surface 10b and is directed toward the projection lens 16, and is projected onto the screen by the projection lens 16. Projected.

[Green ray trace]
The green ray trajectory (path) will be described. The green ray trajectory is basically the same as the blue ray trajectory. The green light 72 output from the green illumination light source 52 positioned below the green liquid crystal reflective panel 2 and the second polarizing beam filter (second PBF) 62 passes through the second PBF 62 and enters the green liquid crystal reflective panel 2. The polarization axis of the green light 72 output from the green illumination light source 52 is adjusted in advance so that the second PBF 62 has a polarization axis that becomes P-polarized light. The direction of the second PBF 62 is set so as to transmit the P polarization axis with respect to the second PBF 62 and reflect the S polarization axis. Therefore, the second PBF 62 transmits the green light 72 having the S polarization axis and transmits the green light 72 The light enters the liquid crystal reflection panel 2.

  When the green liquid crystal reflective panel 2 displays 0% black, the green light 72 is reflected by the green liquid crystal reflective panel 2 as it is, passes through the second PBF 62 while maintaining the P polarization axis, and moves toward the green illumination light source 52 side. Go back.

  When the green liquid crystal reflective panel 2 displays 100% green, the polarization axis is rotated by 90 degrees when the green light 72 is reflected by the green liquid crystal reflective panel 2 through the second PBF 62, so Green modulated light 72m having a polarization axis is obtained. The green modulated light 72m has a polarization axis of S-polarized light and becomes S-polarized with respect to the second PBF 62, and is reflected by the second PBF 62 and travels in the direction of the cross prism 10. The green modulated light 72 m passes through the second linearly polarizing plate 12 disposed between the second PBF 62 and the cross prism 10 before entering the cross prism 10. The polarization transmission axis of the second linearly polarizing plate 12 is set in substantially the same direction as the S-polarized light with respect to the second PBF 62, and the green modulated light 72m can pass through the second linearly polarizing plate 12 as it is.

  As described above, the second optical system is not provided with the second wave plate corresponding to the first and third wave plates. The reflecting surfaces 10a and 10b of the cross prism 10 are formed with coatings (coats) that reflect blue and red, respectively. However, since the reflecting surfaces 10a and 10b pass green, the green modulated light 72m incident on the prism 10 is 72m. Is transmitted, directed toward the projection lens 16, and projected (projected) onto the screen by the projection lens 16.

[Evaluation]
FIG. 5A shows the relationship between the wavelength λ and the transmittance μ of the first PBF 61 to the third PBF 63 (hereinafter referred to as a polarization beam filter (PBF)) used in the projector apparatus 100, for example, a blue liquid crystal reflective panel for blue light 71. 1 is a graph illustrating the incident angles to the angle 1 of 45 ° and 55 °. FIG. 5B shows the relationship between the wavelength λ and the transmittance μ of the polarizing beam splitter (PBS) used in the projector apparatus illustrated in FIG. 7, for example, an incident angle of 45 ° to the blue liquid crystal reflection panel. , A graph illustrating 55 °.

  (1) Comparing the polarization beam splitter (PBS) and the polarization beam filter (PBF), the PBF has a very low wavelength dependency compared to the PBS. In other words, when PBF is used, the transmittances of blue, green, and red having different wavelengths have the same degree of transmittance, so that the change in transmittance due to the wavelength difference depending on the type of the three primary colors is small. As a result, for example, the level of each color reaching the prism 10 is the same condition. Thus, according to the embodiment of the present invention, there is little reduction in luminance and little reduction in contrast. In other words, the F number of the projector apparatus 100 according to the embodiment of the present invention using PBF is smaller than that of the projector apparatus using PBS, and as a result, the brightness is increased and the contrast is also increased.

  (2) PBF has a lower incidence angle dependency than PBS. Therefore, the projector apparatus 100 according to the embodiment of the present invention using PBF has little decrease in transmittance even if the incident light to the liquid crystal reflection panels 1 to 3 has a slight inclination (the variation in transmittance is small). As a result, for example, there is a margin in the arrangement of the blue illumination light source 51, the blue liquid crystal reflective panel 1, and the first polarizing beam filter (first PBF) 61. That is, even if the optical arrangement of the blue illumination light source 51, the first PBF 61, and the blue liquid crystal reflection panel 1 is slightly shifted, the luminance and contrast are hardly decreased. As a result, fine adjustment of the position of the optical component becomes unnecessary after assembling the optical system.

  FIG. 6 is a diagram illustrating a part of a light ray locus for blue in the condenser lens 220, the third PBS 223, the quarter wavelength plate 221, and the green liquid crystal reflection panel 222 in the projector apparatus illustrated in FIG. In the projector device 100, as illustrated in FIG. 3B, for example, when the blue light 71 is modulated, the blue light 71 passes through the first PBF 61 and enters the blue liquid crystal reflection panel 1, and the blue light 71 When modulated by the liquid crystal reflective panel 1, it is reflected by the first PBF 61 and travels toward the cross prism 10. Therefore, the first PBF 61 passes only once. On the other hand, as illustrated in FIG. 6, when PBS is used, blue light is once incident on the third PBS 223 via the condenser lens 220, transmitted through the quarter-wave plate 221, and modulated by the green liquid crystal reflective panel 222. When received, the modulated blue light again enters the third PBS 223, passes through the third PBS 223, and travels toward the cross prism 224. That is, the third PBS 223 is transmitted twice, and the third PBS 223 is transmitted more frequently once than when the PBS is used. If the transmittances of the first PBF 61 and the third PBS 223 are the same, as illustrated in FIG. 6, light is reduced by the amount of one transmission through the third PBS 223. This leads to a decrease in brightness and a decrease in contrast. On the other hand, in the projector device 100 using PBF, the decrease in light is small, so that the decrease in luminance is reduced, and the decrease in contrast is also small.

  Considering the configuration or structure of the projector device 100 illustrated in FIGS. 1A and 1B, as schematically illustrated in FIG. 4, three optical systems for three primary colors are provided around the cross prism 10. Are neatly arranged. Considering in plan view, for example, on the left side of the cross prism 10, a blue first optical system (blue liquid crystal reflection panel 1, second PBF 62, first linearly polarizing plate 11, first half-wave plate 21 is provided. ) Is arranged on the right side of the cross prism 10, and a second red optical system (red liquid crystal reflection panel 3, third PBF 63, third linearly polarizing plate 13, third half-wave plate 23) is arranged. The third optical system for green (green liquid crystal reflective panel 2, second PBF 62, second linearly polarizing plate 12) is disposed on the side facing the projection lens 16 with the cross prism 10 in between. These three optical systems are regularly arranged in three directions of the cross prism 10. Considering three-dimensionally, since the three optical systems are arranged at the same plane position on the surface of the cross prism 10, the size of the projector device 100 in the height direction can be reduced. In such an arrangement, an additional optical system for sorting the blue light 71, the green light 72, and the red light 73, such as a total reflection mirror, is unnecessary. Considering the above, the projector device 100 is easy to arrange and design, and the housing efficiency of the constituent elements is high. Therefore, the projector device 100 can be housed compactly, and can be reduced in size and weight.

  From the viewpoint of ease of arrangement design and accommodation efficiency, polarization separation means for separating polarized light is not limited to PBF and can be widely applied to the present invention. However, a polarization beam filter (PBF) is compared with a polarization beam splitter (PBS). Small, lightweight. As a result, the projector device 100 can be further reduced in size and weight.

  In the projector device, the lamp portion of the light source and the liquid crystal panel portion consume high power and become high temperature, so cooling is required. In the projector apparatus 100 illustrated in FIGS. 1 and 2, the blue liquid crystal reflective panel 1, the green liquid crystal reflective panel 2, and the red liquid crystal reflective panel 3 are driven by the image signal and drive the liquid crystal panel. The power consumption in 100 is high, the temperature becomes high, and cooling is required. Of course, the lamp 501 portion of the light source 500 also consumes a large amount of power, becomes hot, and requires cooling. The blue liquid crystal reflective panel 1, the green liquid crystal reflective panel 2 and the red liquid crystal reflective panel 3 are cooled at the same height. For example, as an example of a cooling means and a cooling method, these liquid crystal reflective panels Cooling measures such as flowing cooling air in the horizontal direction from the cooling fan along the surfaces of the panels 1 to 3 (which may be provided with heat radiating fins on the back surface) are easy, and the cooling effect is also high.

  In the example illustrated in FIGS. 1A and 1B, the blue illumination light source 51, the green illumination light source 52, and the red illumination light source 53 can all be constituted by, for example, one light source 500 illustrated in FIG. The illumination light source 51, the green illumination light source 52, and the red illumination light source 53, that is, the light source 500 are located below the prism 10 and the three optical systems. As described above, since the light source 500 and the optical system can be three-dimensionally separated, a cooling measure can be separately taken.

  The heat radiation amount of the lamp 501 of the light source 500 and the heat radiation amount of the liquid crystal reflection panels 1 to 3 are greatly different, and the heat radiation amount of the lamp 501 is overwhelmingly large. As described above, since the light source 500 and the optical system including the liquid crystal reflection panels 1 to 3 can be arranged separately, the liquid crystal reflection panels 1 to 3 and the like are not affected by the heat of the lamp 501 of the light source 500. can do. Therefore, the cooling measures for the liquid crystal reflective panels 1 to 3 only have to be taken by themselves, and it is not necessary to take unnecessary cooling measures. From this point of view, the cooling fan may be small, and the projector device 100 can be made smaller and lighter. The noise of the cooling fan is also low.

  A light source 500, in particular, a lamp 501 is disposed outside the housing of the projector apparatus 100, containing the components illustrated in FIGS. 1A and 1B, and only white light 520 from the lamp 501 is introduced. If constituted in this way, the cooling measure becomes very simple.

  The wiring connection portions (portions illustrated so that a large number of cables are connected) of the liquid crystal reflection panels 1 to 3 are directed in different directions. Moreover, since the liquid crystal reflection panels 1 to 3 are located at the upper part, wiring to these wiring connection portions is easy. Since the number of cables to the liquid crystal reflection panels 1 to 3 is considerable, the mounting surface has a great effect. As described above, the projector device 100 can be easily wired around (wiring), requires less space for wiring, and can achieve an effect that wiring can be performed in a compact manner.

  As illustrated in FIGS. 1A and 1B, since no components are arranged around the projection lens 16, the arrangement of the projection lens 16 is highly flexible, and the projection lens 16 is shifted in the vertical and / or horizontal directions. Mechanisms are easy to implement. By moving the projection lens 16 substantially parallel to the exit side surface of the cross prism 10, a function of changing the position of the projected image can be easily realized.

  As illustrated in FIGS. 1A and 1B, the liquid crystal reflection panels 1 to 3, the green liquid crystal reflection panel 2, and the red liquid crystal reflection panel 3 are disposed downward. Accordingly, dust or the like floating in the housing of the projector device 100 is difficult to touch the panel surfaces of the liquid crystal reflection panels 1 to 3, and the level of polarized light due to the adhesion of dust is small and display image quality is hardly degraded.

  The imaging optical system including the liquid crystal reflecting panels 1 to 3 is arranged compactly around the cross prism 10, and it is easy to improve the mechanical structural rigidity. For this reason, pixel position misalignment between the three liquid crystal reflection panels 1 to 3 hardly occurs, and an image with high image quality can be obtained.

  The implementation of the image projection apparatus of the present invention is not limited to the above-described examples, and various modifications similar to or similar to the above-described embodiments can be taken.

  For example, the orientation of the projector device 100 illustrated in FIGS. 1A and 1B is the cross prism 10 or the like with the light source 500 (blue illumination light source 51, green illumination light source 52, red illumination light source 53) facing up. The light source 500 and the cross prism 10 may be arranged side by side on the same plane. Moreover, you may make it provide the light source corresponding to each color separately.

1A and 1B are perspective views of an image projection apparatus as an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a light source in the image projection apparatus illustrated in FIGS. 1 (A) and 1 (B). FIGS. 3A and 3B are diagrams illustrating a partial configuration and a ray trajectory of the image projection apparatus illustrated in FIGS. 1A and 1B. FIG. 4 is a diagram illustrating the ray trajectory around the cross prism illustrated in FIGS. 1 (A) and 1 (B). FIGS. 5A and 5B are graphs showing the characteristics of the polarizing beam filter (PBF) and the polarizing beam splitter (PBS), respectively. FIG. 6 is a diagram illustrating a part of a light ray locus for blue in the projector apparatus illustrated in FIG. FIG. 7 is a diagram illustrating an optical system of a reflection type projector apparatus using a polarization beam splitter (PBS).

Explanation of symbols

100 .. Reflection type projector device 1
1. ・ Blue liquid crystal reflective panel (first reflective panel)
2. Green liquid crystal reflective panel (second reflective panel)
3. ・ Red liquid crystal reflective panel (third reflective panel)
10 .. Cross prism 11-13 ... Linear polarizing plate 21, 23 ... Half wave plate 51 ... Blue illumination light source 52 ... Green illumination light source 53 ... Red illumination light source 61-63 ... Polarized light Beam filter (PBF)
71 ·· Blue light, 71m · · Blue modulated light 72 · · Green light, 72m · · Green modulated light 73 · · Red light, 73m · · Red modulated light 500 · · Light source, 501 · · Lamp, 502, 503 · ·・ Flyeye integrator, 504 ・ ・ PS conversion element, 505 ・ ・ Main condenser lens, 506 ・ ・ Red reflective dichroic mirror, 507 ・ ・ Green-blue reflective dichroic mirror, 508, 509 ・ ・ Total reflection mirror, 510 ・ ・ Green reflective Dichroic mirrors, 511, 512, 513 ... Total reflection mirrors, 515, 516 ... Condenser lenses

Claims (12)

A cross prism that combines the three primary colors of red, green, and blue incident from three incident surfaces and emits the light from the emission surface;
A projection lens that is arranged so that light from the exit surface of the cross prism can enter, and projects the light combined by the cross prism onto a screen;
Three individually provided light sources that irradiate the three primary color lights of red, green, and blue as illumination light from the position below the surface on which the cross prism and the projection lens are disposed,
The cross prism is disposed at a position corresponding to the three incident surfaces, and modulates the three primary color lights of red, green, and blue emitted from the three light sources in accordance with an image display signal. Three reflective image display units for display;
Three polarization beam filters that have low wavelength dependence, transmit the first polarized light, and reflect the second polarized light having a polarization axis orthogonal to the first polarized light, each of which has the light source in the vertical direction. And the reflection type image display unit, arranged in a horizontal direction so as to face a corresponding incident surface of the cross prism and at an angle of 45 degrees with respect to the vertical direction, The corresponding primary color light emitted from the light source is transmitted and guided to the corresponding image display unit, and the three primary color modulated image light modulated according to the image display signal in the image display unit is reflected by the polarization beam filter. The three pieces are arranged so as to be incident on the corresponding incident surface of the cross prism, transmit the first polarized light, and reflect the second polarized light having a polarization axis orthogonal to the first polarized light. Bias And beam filters,
With
The display plane of the image display unit is disposed so as to be parallel to a plane perpendicular to the four joint surfaces of the cross prism and orthogonal to the three incident surfaces of the cross prism.
An image projection apparatus characterized by that. The primary color illumination light incident on the polarizing beam filter is set so that its polarization plane is in the direction of P-polarized light with respect to the polarizing beam filter .
The image projection apparatus according to claim 1. The polarizing beam filter is configured such that the S-polarized light as the second polarized light with respect to the polarizing beam filter is reflected and the direction thereof is arranged so as to transmit the P-polarized light as the first polarized light .
The image projection apparatus according to claim 1. The polarizing beam filter is made of a transparent plate-like member, and a polarization separation surface that transmits the first polarized light and reflects the second polarized light is formed on the surface of the plate-like member on the image display unit side. Is ,
The image projection apparatus according to claim 1. When the image display unit displays 0% black, the image display unit does not modulate the incident primary color light,
When the image display unit displays 100% of the corresponding primary color light, the image display unit modulates the incident primary color light so that the plane of polarization rotates approximately 90 degrees .
The image projection apparatus according to claim 1. Between the cross prism and the polarizing beam filter, two primary color lights out of the three primary colors synthesized by reflecting light on the reflection surface of the cross prism are S-polarized with respect to the reflection surface of the cross prism. A half-wave plate for allowing light to enter is arranged so that
The image projection apparatus according to claim 1. Between the half-wave plate and the polarizing beam filter, a linearly polarizing means is disposed so as to be parallel to the half-wave plate, and the transmission axis of the linearly polarizing means is set with respect to the reflecting surface of the cross prism. Configured in the direction to become P polarized light ,
The image projection apparatus according to claim 6. The reflecting surface of the cross prism, the primary light to be synthesized by transmitting light, arranged linearly polarizing means such that the flat row on the incident surface of the primary color light of the cross prism, the linearly polarized light The transmission axis of the means is configured to be P-polarized with respect to the reflection surface of the cross prism .
The image projection apparatus according to claim 1. The image projection apparatus includes a first cooling unit that cools the three light sources.
The image projection apparatus according to claim 1, wherein the image projection apparatus is an image projection apparatus. The image projection apparatus includes a second cooling unit that cools the three reflective image display units.
The image projection apparatus according to claim 1, wherein the image projection apparatus is an image projection apparatus. The projection lens is configured to be movable up and down and / or left and right in parallel with the other side surface of the cross prism .
The image projection apparatus according to claim 1, wherein: Each of the image display units is arranged with a reflective surface facing downward ,
The image projection apparatus according to claim 1, wherein:

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