JP2007256680A - Projection image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection image display device that can converge light beams of respective colors on a DMD in a secure focus matching state, and has excellent use efficiency of the light beams and light projection light by disposing a light emitting element and a condenser lens so that their optical axes have a predetermined angle to an incident surface of a photoconductive member in consideration of color dispersion due to a difference in refractive index when the light beams of the respective colors are incident on a TIR prism. <P>SOLUTION: An LED 1G and condenser lenses 2G and 3G are disposed so that optical axes of the LED 1G and condenser lenses 2G and 3G are nearly orthogonal to the incident surface of a cross dichroic prism 4, and light emitted by the LED 1G is projected nearly vertically from a projection surface of the cross dichroic prism 4. Based upon them, optical paths of light beams emitted by the LEDs 1R and 1B are found, and the arrangement of the LEDs 1R and 1B and condenser lenses 2R and 3R, and 2B and 3B is set. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection-type image display apparatus in which light of each color can be condensed on a DMD in a state where the focal points are surely matched, light utilization efficiency is good, and projection light is bright.

  2. Description of the Related Art Conventionally, there is a projector (projection type image display apparatus) that projects modulated light on an image generated by a light source on a screen as a front projection method and displays an image on the screen. Further, such a configuration of the projection type image display device is also applied to a rear projection system represented by a rear projection television. Projection-type image display devices include those using lamps as light sources and those using light-emitting elements such as lasers and diodes. On the other hand, they are distinguished by the type of spatial light modulator (light valve) that generates the original image to be projected. The case is divided into those using DMD (Digital Mirror Device: registered trademark) and those using a liquid crystal display panel.

FIG. 4 is a schematic diagram showing a configuration of a conventional projection type image display apparatus (DLP system: Digital Light Projector) 30 of a DMD single sheet system using a light emitting element as a light source and one DMD as a light valve. In this projection type image display apparatus, a light emitting diode (LED) is used as a light emitting element.
On three surfaces around the cross dichroic prism 34 as a cubic light guide, an LED 31R that emits red (hereinafter referred to as R) light, an LED 31G that emits green (hereinafter referred to as G) light, And LED31B which light-emits the light of blue (it is hereafter called B) color is arrange | positioned. Condensing lenses 32R and 33R, 32G and 33G, 32B and 33B are disposed between the LEDs 31R, 31G and 31B and the cross dichroic prism 34, respectively. On the exit side of the cross dichroic prism 34, a TIR (Total Internal Reflection) prism 35, a DMD 36, and a projection lens 37 are arranged.

  The cross dichroic prism 34 is provided with a dichroic mirror 34R that reflects R light while transmitting G and B light and a dichroic mirror 34B that reflects B light and transmits R and G light on a diagonal line. The dichroic mirrors 34R and 34B are integrally formed by bonding together prism members constituting the cross dichroic prism 34.

  The R light emitted from the LED 31R and passed through the condenser lenses 32R and 33R is reflected by the dichroic mirror 34R, exits from the cross dichroic prism 34, and travels toward the TIR prism 35. The B light emitted from the LED 31B and passed through the condenser lenses 32B and 33B is reflected by the dichroic mirror 34B, exits from the cross dichroic prism 34, and travels toward the TIR prism 35. The G light emitted from the LED 31G and passing through the condenser lenses 32G and 33G is transmitted through the dichroic mirrors 34R and 34B and emitted from the cross dichroic prism 34 with the optical axis passing through the intersection of the dichroic mirrors 34R and 34B. Then, head to the TIR prism 35. The LEDs 31R, 31G, and 31B are sequentially turned on by time-division driving, and light of each color is combined on the same optical axis in the dichroic prism 34 and then emitted from the cross dichroic prism 34.

  The TIR prism 35 includes a first prism 35a that is a prism having an acute angle in plan view and a second prism 35b that is a right triangle in plan view as shown in the figure. The light incident on the first prism 35a passes through the first prism 35a, enters the second prism 35b, passes through the second prism 35b, and enters the DMD 36. The light incident on the DMD 36 is modulated according to the tilt angle of the micromirror of the DMD 36 that is electrically turned on / off, is incident on the second prism 35b, is reflected by the reflecting surface 35c of the second prism 35b, The light enters the projection lens 37. The R, G, and B lights are sequentially incident on the DMD 36, so that the light of the R, G, and B images is sequentially generated. The light is totally reflected by the reflecting surface 35c of the second prism 35b and passes through the projection lens 37. Are projected onto the screen, and R, G, B images are displayed on the screen. Since each of the R, G, and B images displayed on the screen is switched at a speed higher than human color resolution, it is visually recognized as a color image.

  In Patent Document 1, light emitted from each of R, G, and B LEDs is incident on three incident surfaces of a cross dichroic prism, and emitted light that has passed through a first fly-eye lens and a second fly-eye lens is incident. , G and B combined illumination light, and an enlarged image of the exit pupil of each element lens of the first fly-eye lens is passed through the second fly-eye lens corresponding to this element and the subsequent illumination lens to the DMD panel. There has been disclosed an invention of a projection type image display apparatus that has an optical system that forms an image at a slightly larger size, and that only the light reflected from the ON pixel of the pixel on the DMD panel passes through the projection lens and forms an image on the screen.

  In Patent Document 2, light emitted from an LED is reflected by a paraboloidal reflecting mirror having a semicircular opening so as to be a substantially parallel light flux, and the bottom surfaces of two trapezoidal prisms are joined to each other, and a thin film having a semi-transparent characteristic is joined to the joining surface. A substantially parallel light beam is made incident on the hexagonal prism to which the light is applied and divided into two by the thin film, and the light beam after exiting the prism becomes illumination light having a circular cross section and is guided to the fly-eye lens of the integrator system. An invention of a projection type image display device having a light source device is disclosed.

In Patent Document 3, an R color light source unit in which at least one Y color LED is mixed among a plurality of R color LEDs, a G color light source unit composed of a plurality of G color LEDs, and a B composed of a plurality of B color LEDs. A color light source unit is placed facing each of the three surfaces of the cross dichroic prism so that the Y-color LED emits light simultaneously when emitting G light, and the combined light emitted from both is emitted to the light valve as G-color light. An invention of a projection type image display device configured as described above is disclosed.
JP 2003-186110 A JP 2004-53949 A JP 2005-189277 A

  In the projection type image display device of FIG. 4 and Patent Document 1, light of each color incident from the three incident surfaces of the cross dichroic prism is synthesized on the same optical axis and emitted from the cross dichroic prism. When light is incident on the TIR prism, is color-dispersed based on the difference in refractive index, and is focused on the DMD, there is a problem that the focal points shift from each other. In order to synthesize them on the same optical axis, there is a problem that adjustment of the arrangement of the LED, the condenser lens, the cross dichroic prism, the TIR prism, and the DMD is complicated.

FIG. 5 is a partially enlarged view of the projection-type image display device 30 of FIG.
As shown in FIG. 5, even if the optical axes of the respective colors coincide with each other on the incident side of the TIR prism 35, the respective colors are chromatically dispersed when passing through the TIR prism 35, and the optical axes of the respective colors are transmitted to the DMD 36. Incident in a shifted state.

FIG. 6 is a schematic diagram showing the display area A of the DMD and the condensing area of each color, where (a) is a diagram showing the display area A and the R condensing area R, and (b) is the display. The figure which showed the area A and the condensing area G of G color, (c) is the figure which showed the display area A and the condensing area B of B color.
From FIG. 6, it can be seen that the center of the display area A and the condensing area G is the same for the G color, but the centers of the display area A and the condensing area are shifted for the R and B colors. Therefore, it is necessary to set a large condensing area (illumination area) in advance, resulting in a problem of darkening.

  The present invention has been made in view of such circumstances, and in consideration of chromatic dispersion due to the difference in refractive index when light of each color enters the TIR prism, the optical axes of the light emitting element and the condenser lens are the light guides. By arranging in a state having a predetermined angle with respect to the incident surface, the light of each color can be condensed on the DMD in a state where the focus is surely matched, and the display area of the DMD and the light collection area of the light of each color It is an object of the present invention to provide a projection type image display device that can be made to coincide with the center of the light source, can reduce the light condensing area, has good light use efficiency, and has a bright projection light.

  Furthermore, an object of the present invention is to provide a projection type image display apparatus in which the use efficiency of light is further improved by using a cross dichroic prism or a Philips prism.

  A projection-type image display device according to the present invention includes a light emitting element that emits at least two or more different colors of light, and a light guide that enters the light emitted from each light emitting element and emits the light after total reflection or passage. A DMD having a body, a TIR prism having a reflective surface inside, a micromirror that reflects incident light on and off based on image information, and the light reflected by the DMD is projected onto a projection target A projection-type image display device, wherein the TIR prism condenses the light incident from the light guide onto the DMD and reflects the light reflected by the DMD to the projection lens by the reflection surface The light emitting elements and the condensing lenses are arranged in a state where the optical axes of the light emitting elements and the condensing lenses have a predetermined angle with respect to the incident surface of the light guide, and the light emitting elements emit the condensing lenses. Through the light guide and the TIR prism through the light at the different optical path, characterized in that it is configured to be focused at the focal point in the DMD.

  In the present invention, the light path is obtained from the focal point side, and the light emitting element, the condensing lens, and the light guide are arranged in consideration of chromatic dispersion due to the difference in refractive index when light of each color enters the TIR prism. The light of each color can be collected on the DMD with the focal points reliably aligned. Therefore, the center of the DMD display area and the light collection area of each color coincide with each other without being shifted for each color, so that the light collection area can be made substantially the same size as the display area, and the light utilization efficiency can be increased. Becomes better and the projection light becomes brighter.

  In the projection type image display device according to the present invention, the light emitting element and the condensing lens have light emitted from the light emitting element, the optical axis of the light emitting element and the condensing lens being substantially orthogonal to the incident surface of the light guide. Are arranged so as to be emitted substantially perpendicularly from the emission surface of the light guide.

  In the present invention, first, one light emitting element and a condensing lens are arranged, and based on this, the optical path of light emitted from another light emitting element is obtained, and the arrangement of the light emitting element and the condensing lens can be determined. Therefore, the arrangement is determined in a well-balanced manner, and the arrangement can be easily adjusted.

  The projection type image display apparatus according to the present invention is characterized in that the colors of light emitted by the respective light emitting elements are red, green, and blue, respectively, and the one light emitting element is a light emitting element that emits green light. .

  In the TIR prism, the angles of the optical axes are shifted in the order of red, green, and blue.In the present invention, first, the arrangement of the light emitting element that emits the light and the condensing lens is determined by obtaining the optical path of the green light. The optical paths of red and blue light are determined in a well-balanced manner, so that the arrangement of the light emitting elements that emit red and blue light and the condensing lens are determined, and the arrangement can be easily adjusted.

  In the projection type image display apparatus according to the present invention, the light guide is a cross dichroic prism.

  In the present invention, since the optical path of the light incident from each light emitting element can be shortened and the spread of the light beam can be reduced, the light utilization efficiency is further improved.

  In the projection type image display device according to the present invention, the light guide is a Philips prism.

    In the present invention, the light utilization efficiency is even better.

  According to the present invention, the light emitting element, the condensing lens, and the light guide are disposed in consideration of chromatic dispersion caused by the difference in refractive index when light of each color enters the TIR prism. Can be focused on the DMD in a consistent manner. Accordingly, the center of the DMD display area and the light collection area of each color coincide with each other without being shifted for each color, so that the light collection area can be minimized and the light use efficiency is improved. The projection light becomes brighter. Further, adjustment for aligning the optical axis is unnecessary, and the number of members for adjustment can be reduced. Therefore, the use becomes simple and the apparatus becomes compact and inexpensive.

  According to the present invention, since the cross dichroic prism is used as the light guide, the optical path of the light incident from each light emitting element can be shortened and the spread of the light can be reduced, so that the light utilization efficiency is further improved.

  According to the present invention, since the Philips prism is used as the light guide, the light utilization efficiency is further improved.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing a configuration of a projection type image display apparatus according to Embodiment 1 of the present invention, in which 10 is a projection type image display apparatus.

  The projection-type image display device 10 includes, as light emitting elements of a light source, an LED 1R that emits light of R color, an LED 1G that emits light of G color, and an LED 1B that emits light of B color. The LED 1R, LED 1G, and LED 1B are respectively disposed on three surfaces around the cross dichroic prism 4 having a cubic shape in plan view. LED1R, LED1G, and LED1B are surface-emitting types, and are sequentially turned on by time-division driving.

  Condensing lenses 2R and 3R are disposed between the LED 1R and the opposing surface of the cross dichroic prism 4. Similarly, condensing lenses 2G, 2B and 3G, 3B are arranged between the LEDs 1G, 1B and the opposing surfaces of the cross dichroic prism 4, respectively. On the exit side of the cross dichroic prism 4, a TIR prism 5, a DMD 6, and a projection lens 7 are arranged.

  The cross dichroic prism 4 is formed by joining four right-angle prisms. The dichroic mirror 4R that reflects the R light and transmits the G and B light and the B light are reflected on the joint surface. Is provided on a diagonal line.

  The R light emitted from the LED 1R, condensed by the condenser lenses 2R and 3R, and incident on the cross dichroic prism 4 is reflected by the dichroic mirror 4R, exits the cross dichroic prism 4, and travels toward the TIR prism 5. The B light emitted from the LED 1B, condensed by the condenser lenses 2B and 3B, and incident on the cross dichroic prism 4 is reflected by the dichroic mirror 4B, exits the cross dichroic prism 4, and travels toward the TIR prism 5. . The G light emitted from the LED 1G, condensed by the condenser lenses 2G and 3G, and incident on the cross dichroic prism 4 passes through the dichroic mirrors 4R and 4B with the optical axis passing through the intersection of the dichroic mirrors 4R and 4B. The light passes through, exits from the cross dichroic prism 4, and travels toward the TIR prism 5.

  The TIR prism 5 includes a first prism 5a that is a prism having an acute angle in plan view and a second prism 5b that is a right triangle in plan view. The light incident on the first prism 5a passes through the first prism 5a, enters the second prism 5b, passes through the second prism 5b, and enters the DMD 6. The light incident on the DMD 6 is modulated according to the tilt angle of the micromirror of the DMD 6 that is electrically turned on / off, is incident on the second prism 5b, is totally reflected by the reflecting surface 5c of the second prism 5b, The light enters the projection lens 7.

  R, G, B light is sequentially incident on the DMD 6 from the cross dichroic prism 4, so that R, G, B image light is sequentially generated, reflected, incident on the second prism 5 b of the TIR prism 5, and reflected. The light is totally reflected by the surface 5c, projected onto the screen via the projection lens 7, and R, G, B images are displayed on the screen. Since each of the R, G, and B images displayed on the screen is switched at a speed higher than human color resolution, it is visually recognized as a color image.

  In the present embodiment, the G light emitted from the LED 1G and incident on the cross dichroic prism 4 via the condenser lenses 2G and 3G is emitted perpendicularly to the exit surface from the exit surface of the cross dichroic prism 4, Further, the LED 1G, the condensing lens 2G and the TIR prism 5 and the DMD 6 are focused on the TIR prism 5 and the DMD 6 so that the light is incident on the TIR prism 5, refracted and emitted from the TIR prism 5, and focused on a predetermined position of the DMD 6. 3G and a cross dichroic prism 4 are arranged. The LED 1G is disposed so that its plane is substantially parallel to the incident surface of the cross dichroic prism 4, that is, the optical axes of the LED 1G and the condenser lenses 2G and 3G are substantially orthogonal to the incident surface.

  As described above, since the arrangement of the cross dichroic prism 4 is determined, the optical path of the R light is obtained by considering the refractive index of the R light in the TIR prism 5 and the cross dichroic prism 4 in the reverse direction from the focal point in the DMD 6. The incident angle of the R light with respect to the incident surface of the cross dichroic prism 4, that is, the angle of the optical axis of the LED 1R and the condenser lenses 2R and 3R with respect to the incident surface is determined, and the arrangement of the LED 1R and the condenser lenses 2R and 3R is determined. Similarly, the arrangement of the LED 1B and the condenser lenses 2B and 3R is determined.

Determination of the arrangement of the LEDs 1G and the like based on the optical paths of the respective colors described above is performed by computer simulation or drawing.
In the present embodiment, as described above, since each member is arranged, light of each color is collected by the DMD 6 in a state where the focal points of the R light, the G light, and the B light in the DMD 6 are matched.

2A and 2B are schematic views showing the display area A of the DMD and the condensing areas of the respective colors. FIG. 2A is a diagram showing the display area A and the condensing area R of the R color, and FIG. The figure which showed the area A and the condensing area G of G color, (c) is the figure which showed the display area A and the condensing area B of B color.
FIG. 2 shows that the centers of the display area A of the DMD 6 and the light condensing area of each color coincide with each other without being shifted for each color. Therefore, the condensing area can be minimized, the light use efficiency is improved, and the projection light is brightened.
Further, adjustment for aligning the optical axis is unnecessary, and the number of members for adjustment can be reduced. Therefore, the use becomes simple and the apparatus becomes compact and inexpensive.

Embodiment 2. FIG.
FIG. 3 is a schematic diagram showing the configuration of the projection-type image display device 20 according to Embodiment 2 of the present invention. In the figure, the same parts as those in FIG.
The projection type image display device 20 includes a Philips prism 14 instead of the cross dichroic prism 4 of the projection type image display device 10 as a light guide.

The Phillips prism 14 includes a first prism 14a and a second prism 14b whose plan view is triangular, and a third prism 14c whose plan view is trapezoidal. A first dichroic film 14d is formed inside the surface of the first prism 14a facing the LED 1R, and a second dichroic film 14e is formed inside the surface of the second prism 14b facing the LED 1G. Yes. The first dichroic film 14d reflects R light and transmits G light and B light. The second dichroic film 14e reflects B light and transmits R light and G light.
The first prism 14a and the second prism 14b are arranged such that the surface of the first prism 14a on which the first dichroic film 14d is formed and the surface corresponding to the hypotenuse of the second prism 14b face each other with a predetermined interval. Has been. Further, the outer surface of the second prism 14b on which the second dichroic film 14e is formed and the emission surface of the third prism 14c are joined.

The R light emitted from the LED 1R enters the first prism 14a, is reflected by the surface corresponding to the hypotenuse of the first prism 14a, is further reflected by the first dichroic film 14d, and is emitted from the first prism 14a.
The B light emitted from the LED 1B is incident on the second prism 14b, totally reflected by the surface corresponding to the hypotenuse of the second prism 14b, further reflected by the second dichroic film 14e, and emitted from the second prism 14b. The light passes through the first dichroic film 14d of the first prism 14a and passes through the first prism 14a.
The G light emitted from the LED 1G enters the third prism 14c, passes through the third prism 14c, passes through the second dichroic film 14e, passes through the second prism 14b, and passes through the first dichroic film 14d. Through the first prism 14a.

  The light of each color emitted from the Philips prism 14 and incident on the first prism 5a of the TIR prism 5 passes through the first prism 5a, enters the second prism 5b, passes through the second prism 5b, Incident on DMD6. The light incident on the DMD 6 is modulated according to the tilt angle of the micromirror of the DMD 6 that is electrically turned on / off, is incident on the second prism 5b, is totally reflected by the reflecting surface 5c of the second prism 5b, The light enters the projection lens 7.

  R, G, B light is sequentially incident on the DMD 6 to the Philips prism 14, thereby sequentially generating R, G, B image light, which is totally reflected by the reflecting surface 5c of the second prism 5b, The image is projected onto the screen via the projection lens 7 and R, G, B images are displayed on the screen.

  In the present embodiment, the G light emitted from the LED 1G and incident on the incident surface of the third prism 14c via the condenser lenses 2G and 3G is perpendicular to the emission surface of the first prism 14a. The LED 1G and the condenser lens are output to the TIR prism 5 and the DMD 6 so as to be emitted, further incident on the TIR prism 5, refracted and emitted from the TIR prism, and focused on a predetermined position of the DMD 6. 2G and 3G and a Philips prism 14 are arranged. The LED 1G is arranged so that its plane is substantially parallel to the incident surface, that is, the optical axes of the LED 1G and the condenser lenses 2G and 3G are substantially orthogonal to the incident surface.

  Since the arrangement of the Philips prism 14 is determined as described above, the optical path of the R light is obtained by considering the refractive index of the R light in the TIR prism 5 and the Philips prism 14 in the reverse direction from the focal point in the DMD 6. The incident angle of the light with respect to the incident surface of the Philips prism 14, that is, the angle of the optical axis of the LED 1R and the condenser lenses 2R and 3R with respect to the incident surface is determined, and the arrangement of the LED 1R and the condenser lenses 2R and 3R is determined. Similarly, the arrangement of the LED 1B and the condenser lenses 2B and 3R is determined.

  In the present embodiment, the LEDs 1R, 1G and 1B, and the condenser lenses 2R, 3R, 2G, 3G, 2B and 3B are considered in consideration of chromatic dispersion due to the difference in refractive index when light of each color enters the TIR prism 5. In addition, since the Philips prism 14 is disposed, the light of each color is collected on the DMD 6 in a state where the focal points are surely matched. Accordingly, the light use efficiency is improved and the projection light is brightened.

In the first and second embodiments, the case where an LED is applied as a light emitting element is described. However, the present invention is not limited to this, and other solid semiconductor elements such as an eye-safe laser and a laser diode are used. Also good. Moreover, LED is not limited to a surface emitting type, A bullet type may be sufficient.
Further, in the first and second embodiments, the case where the cross dichroic prism 4 or the Philips prism 14 is applied as the light guide has been described. However, the present invention is not limited to this.

Further, in the first and second embodiments, the case where the arrangement of the LEDs 1G and the like is determined based on the optical path of G light is described, but the present invention is not limited to this, and the optical paths of light of other colors are used as a reference. The arrangement may be determined as follows.
The light emitting elements are not limited to those emitting light of R color, G color, and B color.

It is the schematic which shows the structure of the projection type image display apparatus which concerns on Embodiment 1 of this invention. It is the schematic which showed the display area A of DMD, and the condensing area of each color, (a) is the figure which showed the display area A and the condensing area R of the R color, (b) is the display areas A and G The figure which showed the condensing area G of the color, (c) is the figure which showed the display area A and the condensing area B of the B color. It is the schematic which shows the structure of the projection type image display apparatus which concerns on Embodiment 2 of this invention. It is the schematic which shows the structure of the conventional projection type image display apparatus of DMD 1 sheet system which uses the light emitting element for a light source, and uses one DMD for a light valve. FIG. 5 is a partially enlarged view of the projection type image display device of FIG. 4. It is the schematic which showed the display area A of DMD, and the condensing area of each color, (a) is the figure which showed the display area A and the condensing area R of the R color, (b) is the display areas A and G The figure which showed the condensing area G of the color, (c) is the figure which showed the display area A and the condensing area B of the B color.

Explanation of symbols

10, 20 Projection type image display device 1R, 1G, 1B LED
2R, 3R, 2G, 3G, 2B, 3B Condensing lens 4 Cross dichroic prism 4R, 4B Dichroic mirror 5 TIR prism 5a First prism 5b Second prism 5c Reflecting surface 6 DMD
7 Projection lens 14 Phillips prism 14a First prism 14b Second prism 14c Third prism 14d First dichroic film 14e Second dichroic film

Claims (5)

A light emitting element that emits light of at least two different colors, a condensing lens that condenses the light emitted by each light emitting element, and light emitted from each condensing lens is incident, and the light is totally reflected or transmitted Light emitting body, a TIR prism having a reflecting surface inside, a DMD having a micromirror that reflects incident light on and off based on image information, and light reflected by the DMD The TIR prism condenses the light incident from the light guide to the DMD and reflects the light reflected by the DMD to the projection lens by the reflection surface. In the projection type image display device to be
Each light emitting element and the condensing lens are arranged in a state where the optical axis of the light emitting element and the condensing lens has a predetermined angle with respect to the incident surface of the light guide, and each light emitting element emits and passes through the condensing lens. The projection type image display apparatus is configured such that the collected light passes through the light guide and the TIR prism in different optical paths and is collected at the focal point of the DMD.   In one light emitting element and the condensing lens, the optical axes of the light emitting element and the condensing lens are substantially perpendicular to the incident surface of the light guide, and the light emitted from the light emitting element is substantially perpendicular to the light emitting surface of the light guide. The projection-type image display device according to claim 1, wherein the projection-type image display device is disposed so as to emit light. The color of the light emitted from each light emitting element is red, green and blue,
The projection type image display device according to claim 2, wherein the one light emitting element is a light emitting element that emits green light.   The projection type image display device according to claim 1, wherein the light guide is a cross dichroic prism.   The projection type image display device according to claim 1, wherein the light guide is a Philips prism.

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