JP2009180793A - Projection-type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection-type display device equipped with optical components that attains the functions of separating illumination projection light and of separating and composing colors, using a simple, inexpensive and small-sized configuration with few constraints. <P>SOLUTION: The projection-ype display device is equipped with a color separating and compositing prism 10 having a dichroic film 14 on a prism-jointed face 13 of prisms 11, 12, the dichroic film determining the transmission reflection characteristics of polarized light in each color wavelength range, depending on an incident angle difference between a first incident angle and a second incident angle. The illumination light having passed through a filter member that selectively changes the polarization directions in accordance with wavelengths is made to enter the dichroic film 14, at a first incident angle and is then separated by the dichroic film 14 into a plurality of color beams; the separated color beams are guided to DMD elements 6R, 6GB for the respective color beams and are modulated by the plurality of DMD elements 6R, 6GB; the plurality of exiting color beams are made to enter the dichroic film 14 at a second incident angle; and the color beams are subjected to color compositing by the dichroic film 14 to exit toward a projection lens. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a projection display device using a plurality of reflective spatial light modulators.

  Conventionally, there are various types of projection display devices. As an example, there is a multi-plate projection display device using a plurality of reflective spatial light modulators.

  As one of such projection display devices, there is a projection display device using a reflection type light valve as a reflection type spatial light modulator as disclosed in Patent Document 1. FIG. 10 is a schematic configuration diagram showing an outline of the projection display device disclosed in Patent Document 1. As shown in FIG. In this projection display device, first, illumination light from the light source 101 is transmitted through the polarizing film 102a of the polarization beam splitter 102, and the color separation / combination prism 103, which is a combination of the first to third prisms 103A, 103B, and 103C. To enter. Here, of the illumination light, the blue light B is reflected by the blue reflecting dichroic film 103a of the first prism 103A, is color-separated, is totally reflected by the prism surface 103b, and is guided to the blue reflective liquid crystal light valve 104B. Of the illumination light, the red light R is reflected by the red reflecting dichroic film 103c on the joint surface of the second and third prisms 103B and 103C, and is color-separated to be totally reflected by the prism surface 103d, thereby reflecting for red. Guide to the liquid crystal light valve 104R. Of the illumination light, the green light G is transmitted through the red reflective dichroic film 103c to be color-separated, totally reflected by the prism surface 103e, and guided to the green reflective liquid crystal light valve 104G.

  Each of the reflective liquid crystal light valves 104B, 104R, and 104G has a large number of pixels, and has a modulation function that converts incident light of P-polarized light to a pixel portion selected by a color signal into S-polarized light and reflects and emits the light. Have. The reflected light from these reflective liquid crystal light valves 104B, 104R, and 104G travels in the opposite direction to the incident light (illumination light), and enters the polarization beam splitter 102 again as color-combined light on the prism surface 103b. Here, S-polarized light, which is modulated light among the color synthesized light, is separated from the illumination light by being reflected by the polarizing film 102a, is incident as projection light on the projection lens 105, and is projected onto the screen or the like by the projection lens 105. Is done.

  Further, as shown in Non-Patent Document 1, there is a DLP (Digital Light Processing) type projection display device using a DMD element (Digital Micromirror Device) as a reflective spatial light modulator. FIG. 11 is a schematic configuration diagram showing an outline of a two-chip projection display device disclosed in Non-Patent Document 1. In this projection display device, first, the yellow Y region that transmits the red light R and the green light G in the illumination light (white light) emitted from the light source 111, and the red light R and the blue light B are transmitted. A magenta M region is provided with a color wheel 112 that is alternately switched in a time-division manner with respect to the optical axis. The illumination light that has passed through the color wheel 112, the integrator rod 113, and the relay optical system 114 is incident on the illumination projection separation prism 115 including the prisms 115A and 115B, and is totally reflected by the prism surface 115a having an air gap to be prism 116A. , 116B is incident on the color separation / combination prism 116. Of the illumination light incident on the color separation / combination prism 116, the red light R is color-separated by being reflected by the red reflecting dichroic film 116a, totally reflected by the prism surface 116b, and guided to the red DMD element 117R. On the other hand, among the illumination lights incident on the color separation / combination prism 116, the green light G or the blue light B is time-divisionally transmitted through the red reflecting dichroic film 116a according to the rotation of the color wheel 112, and is separated into green / blue. To the DMD element 117GB.

  Here, the DMD elements 117R and 117GB are semiconductor projection devices in which an infinite number of micrometer-sized miniature reflecting mirrors are arranged, and angle control is performed by a high-speed shake operation of a predetermined shake angle ± 12 °, for example, based on a color signal. By doing this, the color light is modulated so as to project the color light deflected and reflected. The red light R reflected by the DMD element 117R enters the prism surface 116c of the color separation / combination prism 116 substantially perpendicularly, is totally reflected by the prism surface 116b, and is further reflected by the red reflecting dichroic film 116a for illumination projection separation. The light is projected onto the projection lens 118 via the prism 115. On the other hand, the green light G or the blue light B reflected in a time division manner by the DMD element 117GB is incident on the prism surface 116d of the color separation / combination prism 116 substantially perpendicularly, passes through the dichroic film 116a, and is combined with the red light R. Then, the light passes through the illumination projection separation prism 115 and is projected onto the projection lens 118.

  FIG. 12 is a schematic configuration diagram showing an overview of a three-chip projection display device disclosed in Non-Patent Document 1. In this projection display device, first, the illumination light (white light) emitted from the light source 121 passes through the integrator rod 122 and the relay optical system 123 and enters the illumination projection separation prism 124 including the prisms 124A and 124B. Then, the light is totally reflected by the prism surface 124a having an air gap and enters the color separation / combination prism 125 including the prisms 125A, 125B, and 125C. Of the illumination light incident on the color separation / combination prism 125, the blue light B is color-separated by being reflected by the blue reflecting dichroic film 125a, totally reflected by the prism surface 125b, and guided to the blue DMD element 126B. On the other hand, of the illumination light incident on the color separation / combination prism 125, the red light R is transmitted through the blue reflective dichroic film 125a and then reflected by the red reflective dichroic film 125c to be color-separated and a prism surface 125d having an air gap. Are totally reflected and guided to the red DMD element 126R. Further, the green light G passes through the blue reflective dichroic film 125a and the red reflective dichroic film 125c and is guided to the green DMD element 126G.

  The blue light B reflected by the DMD element 126B is substantially perpendicularly incident on the prism surface 125e of the color separation / combination prism 125, totally reflected by the prism surface 125b, and further reflected by the blue reflective dichroic film 125a for illumination projection separation. The light is projected onto the projection lens 127 through the prism 124. The red light R reflected by the DMD element 126R enters the prism surface 125f of the color separation / combination prism 125 substantially perpendicularly, is totally reflected by the prism surface 125d, is further reflected by the red reflecting dichroic film 125c, and is projected by illumination. The light is projected onto the projection lens 127 through the separation prism 124. Further, the green light G reflected by the DMD element 126G is incident on the prism surface 125g of the color separation / combination prism 125 substantially perpendicularly, and is transmitted through the red reflection dichroic film 125c and the blue dichroic film 125a. The light B is color-combined and transmitted through the illumination projection separation prism 124 and projected onto the projection lens 127.

  Furthermore, as disclosed in Patent Document 2, there is a three-plate projection display device using a DMD element as a reflective spatial light modulator. FIG. 13 is a schematic plan view showing an outline of the projection display device disclosed in Patent Document 2, and FIG. 14 is a schematic side view thereof. In this projection display device, the illumination light incident on the total reflection type light separation prism 131 is totally reflected by the total reflection surface 131 a and enters the cross dichroic prism 132. The illumination light incident on the cross dichroic prism 132 is separated into three primary colors of red light R, green light G, and blue light B on the two cross dichroic surfaces 132a and 132b. The separated color lights are directed in three directions orthogonal to each other, and are incident on DMD elements 133R, 133G, and 133B corresponding to the respective color lights. Each DMD element 133R, 133G, 133B forms an image corresponding to each color light by turning on / off the minimal reflector, and deflects and reflects the image.

  Each color light (modulated light) deflected and reflected by each DMD element 133R, 133G, 133B is recombined by the cross dichroic prism 132, travels to the projection lens 134 through the total reflection type separation prism 131, and is projected onto the screen or the like. .

JP 2000-171923 A JP 2007-25287 A Optical technology information magazine "Light Edge" No. 19 / Special Feature Video ... Toward the Digital Age (July 2000) Chapter 3

  However, in the case of the projection display device disclosed in Patent Document 1, the polarization beam splitter 102 for performing illumination projection separation and the prism 103 for performing color separation / combination are configured separately. In addition, the polarization beam splitter 102 includes two prisms 102A and 102B, and the color separation / combination prism 103 includes three different types of prisms 103A to 103C, which requires a total of five prisms. In place of the three-plate reflective liquid crystal light valve, a two-plate reflective light valve may be used, and the color separation / combination prism is composed of two different types of prisms, for a total of four prisms. Is required. Therefore, the number and types of optical components for illumination projection separation and color separation / synthesis are large, which is a factor that increases the size and cost of the optical system.

  Further, since at least two prisms 103A and 103B constituting the color separation / combination prism 103 are arranged through an air gap for total reflection, it is necessary to hold both of them while ensuring the accuracy of the air gap. It is difficult and the manufacturing of the prism 103 is complicated and requires a high manufacturing cost. An air gap is also required between the color separation / combination prism 103 and the polarization beam splitter 102 for total reflection, and it is difficult to hold both while ensuring the accuracy of the air gap. The production of the beam splitter 102 is complicated and requires manufacturing costs. In addition, there is light (especially, red light R and blue light B that reciprocates through the air gap) that passes through the air gap disposed obliquely with respect to the optical axis before reaching the projection lens 105, and the light amount loss is large. It becomes a thing.

  These problems also occur in the cases of the illumination projection separation prisms 115 and 124 and the color separation / combination prisms 116 and 125 in Non-Patent Document 1, the total reflection type light separation prism 131 and the cross dichroic prism 132 disclosed in Patent Document 2. It is the same.

  That is, according to these prior arts, there are problems due to separate illumination projection separation and color separation / synthesis, and problems associated with air gaps.

  The present invention has been made in view of the above, and has solved the problems associated with the air gap and has realized an optical projection separation and color separation / synthesis function with a simple, inexpensive, and compact configuration. It is an object of the present invention to provide a projection display device comprising:

  In order to solve the above-described problems and achieve the object, a projection display device according to the present invention includes a plurality of reflective spatial light modulators that modulate color light based on color signals, and wavelength selection of the polarization direction of illumination light. A projection type display device comprising a filter member for converting an image and a projection lens, comprising a first prism element and a first prism element, and a first incident angle on a prism joint surface of the first prism element and the second prism element. And a color separation / combination prism having a dichroic film in which transmission and reflection characteristics of polarized light in each color wavelength range are determined depending on the difference in incident angle between the second incident angle and the second incident angle, and the illumination light passing through the filter member is The light is incident on the dichroic film at the first incident angle and is separated into a plurality of color lights by the dichroic film, and the separated color lights are guided to the reflection type spatial light modulators for the corresponding color light, and the plurality of reflection types Spatial light change A plurality of color lights emitted after being modulated by a projector are incident on the dichroic film at the second incident angle, and color synthesis is performed by the dichroic film and emitted toward the projection lens. Projection display device.

  In the projection display device according to the present invention as set forth in the invention described above, the dichroic film has different characteristics in wavelength regions to be transmitted and reflected in accordance with an incident angle.

  In the projection display device according to the present invention as set forth in the invention described above, the dichroic film has a characteristic that a wavelength region to be transmitted and reflected is shifted in accordance with an incident angle.

  In the projection display device according to the present invention as set forth in the invention described above, the first prism element includes illumination light for the first surface portion on which the illumination light is incident and the first reflective spatial light modulator. And a second surface portion that allows passage of both the incident light of the modulated light from the reflective spatial light modulator, and the second prism element has the second reflective spatial light modulation. A third surface portion that transmits both of the illumination light emitted from the reflector and the incident modulated light from the reflective spatial light modulator and a fourth surface that is color-combined and transmits the modulated light toward the screen And a portion.

  In the projection display device according to the present invention as set forth in the invention described above, the first prism element has a shape in which a triangle can be defined by the first surface portion, the second surface portion, and the joint surface. The second prism element has a shape in which a triangle can be defined by the third surface portion, the fourth surface portion, and the joint surface.

  In the projection display device according to the present invention as set forth in the invention described above, the first and second prism elements each have a triangular prism shape.

  Further, the projection display device according to the present invention is the reflection surface according to the above-described invention, in the optical path from the dichroic film to each reflective spatial light modulator and the optical path from each reflective spatial light modulator to the dichroic film. It is characterized by not having.

  In the projection display device according to the present invention, in the above invention, the modulated light emitted from the modulation surface of each of the reflection type spatial light modulators and directed to the screen is directed to the upper surface of the reflection type spatial light modulator. The light is emitted in a vertical direction.

  In the projection display device according to the present invention, in the above invention, as the reflective spatial light modulator, a reflective spatial light modulator for one of the three primary colors and the remaining two of the three primary colors. It is a two-plate type provided with a reflective spatial light modulator that shares colors in a time-sharing manner.

  The projection type display apparatus according to the present invention comprises first and second prism elements, and has an incident angle between a first incident angle and a second incident angle on a prism joint surface of the first and second prism elements. A color separation / combination prism having a dichroic film whose transmission and reflection characteristics of polarized light in each color wavelength range are determined depending on the difference, and the illumination light having passed through the filter member is incident on the dichroic film at a first incident angle. The dichroic film separates the color light into a plurality of color lights, guides the separated color lights to the corresponding color light reflection type spatial light modulators, and dichroics the plurality of color lights emitted after being modulated by the plurality of reflection type spatial light modulators. Since the light is incident on the film at the second incident angle and is synthesized by the dichroic film and emitted toward the projection lens, it is illuminated by a simple, inexpensive, and compact single-junction color separation / combination prism. An effect that can realize the functions of the projection separation and color separation synthesis. For this purpose, it is only necessary to provide a single color separation / combination prism having a dichroic film having a predetermined characteristic on the prism bonding surface, so that no air gap is present on the optical path of illumination light or projection light. Therefore, there is an effect that it is possible to solve problems such as light loss associated with the air gap.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection display device that is the best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a schematic configuration diagram showing a projection display device according to the present embodiment. The projection display device 1 according to the present embodiment is applied to a DLP (Digital Light Processing) type two-plate projection display device using a DMD element (Digital Micromirror Device) as a reflective spatial light modulator. Show.

  The projection display device 1 of the present embodiment generally includes a light source 2, a wavelength selective polarizing element 3, an integrator rod 4, a relay optical system 5, a color separation / combination prism 10, two DMD elements 6G and 6RB, And a projection lens 7.

  The light source 2 is for emitting and outputting white light as illumination light for illuminating the DMD elements 6G and 6RB. The wavelength selective polarization element 3 is provided as a filter member for converting the polarization direction of white light (illumination light) emitted from the light source 2 from P polarization to S polarization in a wavelength selective manner. FIG. 2 is a schematic front view illustrating a configuration example of the wavelength selective polarizing element 3. The wavelength-selective polarizing element 3 used in the present embodiment is formed in a wheel shape and is driven to rotate around a central axis. For example, the regions R-CS and B-CS that are equally divided into four in a radial manner are provided. Have alternately. The region R-CS is a region in which the polarization direction of the red light R in the three primary colors RGB included in the white light is converted from P-polarized light to S-polarized light, and the green light G and the blue light B are transmitted without being subjected to polarization conversion. . The region B-CS is a region where the polarization direction of the blue light B in the three primary colors RGB included in the white light is converted from P-polarized light to S-polarized light, and the green light G and the red light R are transmitted without being subjected to polarization conversion. . Therefore, by rotating the wavelength-selective polarizing element 3 with these regions R-CS and B-CS positioned on the optical axis of white light, the polarization states of the red light R and the blue light B are time-divisionally divided. The light is alternately converted from P-polarized light to S-polarized light, and the green light G is not polarized and is always effective as projection light. In addition, the division | segmentation number which comprises area | region R-CS and B-CS may be appropriate, for example, an equally 2 division | segmentation structure may be sufficient. Further, if a polarization conversion element that aligns the polarization state of white light with P-polarized light is provided in front of the wavelength-selective polarizing element 3, the light utilization efficiency is improved.

  The integrator rod 4 is provided as necessary to homogenize the illumination light, and may be a fly-eye lens or the like. The relay optical system 5 is for making the illumination light that has passed through the integrator rod 4 enter a predetermined position of the color separation / combination prism 10.

  Further, as shown in Non-Patent Document 1, Patent Document 2, and the like, the DMD element is a semiconductor projection device in which an infinite number of microscopic reflectors having a size of μm are arranged. The color light is modulated so as to project the color light deflected and reflected by performing angle control (on / off control) by a high-speed shake operation of 12 °. In the present embodiment, a wavelength selective polarizing element is used for two colors of DMD element 6G for green light G, which is one of the three primary colors RGB, and red light R and blue light B, which are the remaining two colors. 3 is configured as a two-plate type including a DMD element 6RB shared in a time-sharing manner.

  Furthermore, the projection lens 7 is for projecting projection light emitted from the color separation / combination prism 10 as color light modulated by the DMD elements 6G and 6RB onto a screen (not shown).

  Next, the color separation / combination prism 10 that characterizes the present embodiment will be described. FIG. 3 is a front view illustrating a configuration example of the color separation / combination prism. The color separation / combination prism 10 used in the present embodiment is entirely cubic by joining two triangular prisms (prism elements) 11 and 12 having a triangular symmetrical cross section together at a prism joint surface 13. The dichroic film 14 is provided on the prism joint surface 13. The color separation / combination prism 10 may have a cubic shape as a function, and may have a shape in which a part of the top portion is cut away. In that case, a triangular top portion or the like which is a cross section of the triangular prisms 11 and 12 is partially cut out. This triangle may be left-right symmetric or asymmetric. The prism 11, which is the first prism element, has a shape in which a triangle can be defined by the prism surfaces 10a and 10b and the prism joint surface 13, and is three-dimensionally triangular. The prism 12, which is the second prism element, has a shape in which a triangle can be defined by the prism surfaces 10c and 10d and the prism joint surface 13, and has a triangular prism shape in three dimensions.

  Here, the dichroic film 14 has an incident angle dependency in which the transmission and reflection characteristics of polarized light in each color wavelength region are determined depending on the difference in the incident angle. Functions for color synthesis of light. 4A and 4B are characteristic diagrams showing the incident angle dependence of the dichroic film 14 used in the present embodiment. FIG. 4A shows the transmission / reflection characteristics of the dichroic film 14 in the respective RGB wavelength ranges when P-polarized light is incident on the dichroic film 14 at an incident angle of 62 °. In this case, the P-polarized light in the blue B wavelength region and the red R wavelength region is reflected by the dichroic film 14, whereas the P-polarized light in the green G wavelength region shows a characteristic of transmitting through the dichroic film 14. S-polarized light is reflected by the dichroic film 14 in any wavelength region.

  On the other hand, FIG. 4B shows the transmission / reflection characteristics of the dichroic film 14 in the respective RGB wavelength ranges when P-polarized light is incident on the dichroic film 14 at an incident angle of 45 °. In this case, the P-polarized light in the blue B wavelength region and the red R wavelength region is transmitted through the dichroic film 14, whereas the P-polarized light in the green G wavelength region is reflected by the dichroic film 14. S-polarized light is reflected by the dichroic film 14 in any wavelength region.

  That is, in FIG. 4, the dichroic film 14 has a difference between an incident angle of 62 ° and an incident angle of 45 °. P and P-polarized light in the red R wavelength region have a characteristic of shifting from reflection to transmission so that the transmission and reflection characteristics are inverted.

Therefore, the optical path is set so that the illumination light incident on the color separation / combination prism 10 from the prism surface 10a via the wavelength selective polarizing element 3 is incident on the dichroic film 14 at the first incident angle θ ₁ = 62 °. Has been. Further, the green light G (P-polarized light) that has passed through the dichroic film 14 passes through the prism surface 10 c as it is and is emitted from the color separation / combination prism 10 without being reflected or totally reflected in the color separation / combination prism 10. Thus, the optical path is set so that the light is directly guided to the DMD element 6G and illuminated obliquely with respect to the upper surface of the DMD element 6G. Further, the red light R and the blue light B reflected by the dichroic film 14 pass through the prism surface 10 b as they are and are emitted from the color separation / synthesis prism 10 without being reflected or totally reflected in the color separation / synthesis prism 10. Thus, the optical path is set so as to be guided directly to the DMD element 6RB and illuminate the upper surface of the DMD element 6RB.

Further, in accordance with the deflection reflection due to the swing operation of the micromirror accompanying the on / off control of the DMD element 6G, the projection light re-entering the prism surface 10c at an angle different from the illumination light by the DMD element 6G is reflected in the color separation / combination prism 10. The optical path is set so as to go directly to the dichroic film 14 without being totally reflected. That is, illumination light is incident on the upper surface of the DMD element from an oblique direction, and so-called on-light of the modulated light emitted from the DMD element toward the screen (projection lens 7) is incident on the upper surface of the DMD element. In contrast, the light is emitted vertically. At this time, the projection light by the green light G is set to enter the dichroic film 14 at the second incident angle θ ₂ = 45 °. In addition, according to the deflection reflection due to the swing operation of the micromirror accompanying the on / off control of the DMD element 6RB, the projection light that is incident again on the prism surface 10b at an angle different from the illumination light by the DMD element 6RB is reflected in the color separation / combination prism 10. The optical path is set so as to go directly to the dichroic film 14 without being totally reflected. At this time, the projection light by the red light R and the blue light B is set to enter the dichroic film 14 at the second incident angle θ ₂ = 45 °. Here, in the present embodiment, the prism surface 10d serves as a projection light emitting surface, and the projection lens 7 is positioned at a predetermined position with respect to the prism surface 10d.

  In such a configuration, the operation of the color separation / combination prism 10 will be described with reference to FIGS. First, the P-polarized light of the red light R and the blue light B in the illumination light emitted from the light source 2 is alternately converted to S-polarized light by the wavelength-selective polarizing element 3, and the P-polarized light of the green light G remains in the P-polarized wavelength. The light passes through the selective polarizing element 3.

Here, the green light G (P-polarized light) transmitted through the wavelength selective polarizing element 3 is transmitted through the prism surface 10a of the color separation / combination prism 10 and is incident on the dichroic film 14 at the first incident angle θ ₁ = 62 °. To do. At this time, according to the characteristic shown in FIG. 4A, the wavelength selective polarizing element 3 has a characteristic of transmitting green light G (P-polarized light). Therefore, the green light G (P-polarized light) incident on the wavelength selective polarizing element 3 at the first incident angle θ ₁ = 62 ° is transmitted through the wavelength selective polarizing element 3 as shown in FIG. Then, the light is directly guided to the green DMD element 6G through the prism surface 10c, and illuminates the DMD element 6G.

On the other hand, the red light R (P-polarized light) and the blue light B (S-polarized light) or the red light R (S-polarized light) and the blue light B (P-polarized light) transmitted through the wavelength selective polarizing element 3 And enters the dichroic film 14 at a first incident angle θ ₁ = 62 °. At this time, according to the characteristics shown in FIG. 4A, the wavelength-selective polarizing element 3 has a characteristic of reflecting the red light R and the blue light B regardless of whether the polarization direction is P-polarized light or S-polarized light. . Therefore, the red light R (P-polarized light) and the blue light B (S-polarized light) or the red light R (S-polarized light) and the blue light B incident on the wavelength selective polarizing element 3 at the first incident angle θ ₁ = 62 °. As shown in FIG. 5B, (P-polarized light) is reflected by the wavelength-selective polarizing element 3, and directly guided to the red and blue DMD elements 6RB through the prism surface 10b, and illuminates the DMD element 6RB. To do. That is, since there is no polarization beam splitter on the illumination optical path, the shared DMD element 6RB is always reflected by the dichroic film 14 and illuminated as it is by the red light R and the blue light B that have passed through the prism surface 10b. In this way, the illumination light is color-separated into green light G, red light R, and blue light B by the dichroic film 14.

The DMD element 6G illuminated with the green light G (P-polarized light) performs a modulation operation based on the green color signal, deflects the green light G (P-polarized light), as shown in FIG. The light is incident again on the prism surface 10c at an angle different from that of the illumination light. The green light G (P-polarized light) is directly guided to the dichroic film 14 as it is, but is incident on the dichroic film 14 at a second incident angle θ ₂ = 45 °. At this time, according to the characteristic shown in FIG. 4B, the wavelength-selective polarizing element 3 has a characteristic of reflecting the green light G (P-polarized light). Accordingly, the green light G (P-polarized light) incident on the wavelength selective polarizing element 3 at the second incident angle θ ₂ = 45 ° is reflected by the wavelength selective polarizing element 3 as shown in FIG. Then, the light is emitted from the prism surface 10d as projection light toward the projection lens 7 as it is.

On the other hand, when the illumination light strikes the R-CS region of the wavelength selective polarizing element 3, the DMD element 6RB illuminated with the red light R (S-polarized light) and the blue light B (P-polarized light) A modulation operation is performed based on the color signal, and as shown in FIG. 6B, the red light R (S-polarized light) and the blue light B (P-polarized light) are deflected to illuminate the prism surface 10b. Re-enter at a different angle. The red light R (S-polarized light) and the blue light B (P-polarized light) are directly guided to the dichroic film 14 as they are, but are incident on the dichroic film 14 at a second incident angle θ ₂ = 45 °. At this time, according to the characteristic shown in FIG. 4B, the wavelength selective polarizing element 3 has a characteristic of transmitting the blue light B (P-polarized light) and reflecting the red light R (S-polarized light). Therefore, as shown in FIG. 6B, the blue light B (P-polarized light) modulated based on the blue color signal passes through the wavelength-selective polarizing element 3 and is directly used as projection light from the prism surface 10d. The red light R (S-polarized light) emitted toward the projection lens 7 is reflected by the wavelength selective polarizing element 3 and discarded.

In addition, when the illumination light strikes the B-CS region of the wavelength selective polarization element 3, the DMD element 6RB illuminated with the red light R (P polarization) and the blue light B (S polarization) A modulation operation is performed based on the color signal, and as shown in FIG. 6C, the red light R (P-polarized light) and the blue light B (S-polarized light) are deflected to illuminate the prism surface 10b. Re-enter at a different angle. The red light R (P-polarized light) and the blue light B (S-polarized light) are directly guided to the dichroic film 14 as they are, but are incident on the dichroic film 14 at a second incident angle θ ₂ = 45 °. At this time, according to the characteristic shown in FIG. 4B, the wavelength selective polarizing element 3 has a characteristic of transmitting the red light R (P-polarized light) and reflecting the blue light R (P-polarized light). Therefore, as shown in FIG. 6C, the red light R (P-polarized light) modulated based on the red color signal passes through the wavelength-selective polarizing element 3 and is directly used as projection light from the prism surface 10d. The blue light B (S-polarized light) emitted toward the projection lens 7 is reflected by the wavelength selective polarizing element 3 and discarded.

  That is, the green light G (P-polarized light) shown in FIG. 6A is always projected, and the blue light B (S-polarized light) and red light R (S-polarized light) shown in FIGS. 6B and 6C are projected. Are alternately performed in a time-sharing manner. Therefore, as the projection light for the projection lens 7, by the function of the dichroic film 14, the color synthesis of the green light G and the blue light B or the green light G and the red light R is alternately performed in a time division manner. The synthesized color image is displayed on the screen.

  As described above, according to the projection display device 1 of the present embodiment, one simple, inexpensive, and compact one that is formed into a cubic shape by joining two triangular prisms 11 and 12 having the same shape. With only the color separation / combination prism 10, illumination projection separation and color separation / synthesis can be performed, and the components constituting the optical system for illumination projection separation and color separation / synthesis can be reduced. In particular, since each separated color light is directly guided to the DMD elements 6G and 6RB without being reflected or totally reflected, each prism surface 10a to 10d is not restricted by the total reflection condition and the like, and the design is free. The degree can be improved. Further, by forming the entire color separation / combination prism 10 in a cubic shape, the size can be further reduced as compared with the case where the color separation / combination prism 10 is formed in a kester shape. Further, since it is only necessary to provide one junction type color separation / combination prism 10 having a dichroic film 14 having predetermined characteristics on the prism joint surface 13, an optical system for illumination projection separation and color separation / combination is configured. There is no air gap in the color separation / combination prism 10, and problems such as a decrease in the amount of light accompanying the air gap can be avoided.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Hereinafter, various modifications will be exemplified.

(Modification 1)
FIG. 7 is a diagram illustrating an XY plan view, a YZ plan view, and a cross-sectional view thereof as a configuration example of the wavelength-selective polarizing element 3A of the first modification. In the first modification, a drum-shaped wavelength selective polarizing element 3 </ b> A is used in place of the wheel-shaped wavelength selective polarizing element 3. The wavelength-selective polarizing element 3 </ b> A is such that the regions R-CS and B-CS are alternately and equally divided on the outer peripheral surface thereof, and are rotationally driven. -CS and B-CS exhibit a polarization direction conversion function in a time-sharing manner, and are reflected in a desired direction by a truncated cone-shaped mirror 41 integrally formed therein.

  In place of the mirror 41 integrated with the wavelength selective polarizing element 3A, as shown in FIG. 8, the light transmitted through the wavelength selective polarizing element 3A is reflected in a desired direction by a fixed mirror 42 fixedly arranged. It may be.

  Furthermore, as shown in FIG. 9, the incident direction with respect to the wavelength selective polarizing element 3A and the mirror 41 may be set in reverse. At this time, if the illumination light from the light source 2 is condensed in the vicinity of between the wavelength-selective polarizing element 3A and the integrator rod 4, the light beam diameters in the drum-shaped wavelength-selective polarizing element 3A and the integrator rod 4 are reduced. Can be small.

(Modification 2)
In addition, a color switch (registered trademark) manufactured by Color Link may be used as the filter member. Further, not only the rotary wavelength selective polarizing elements 3 and 3A, but also a type that reciprocates linearly may be used.

In the present embodiment, the two-plate configuration relating to the reflective spatial light modulator is shared by the red light R and the blue light B in a time-sharing manner, but the green light G and the red light are shared. It may be shared in time division for R, or may be shared in time division for green light G and blue light B. In that case, of course, characteristics different from the characteristics described in FIG. The wavelength-selective polarizing elements 3 and 3A (filter member) may be configured to change the color light that changes the polarization direction in accordance with such a configuration. Further, in the present embodiment, the first incident angle θ ₁ = 62 ° and the second incident angle θ ₂ = 45 ° with respect to the dichroic film 14 are set, but the first incident angle θ ₁ is exchanged. = 45 ° and the second incident angle θ ₂ = 62 ° may be used to change the color separation characteristics and the color synthesis characteristics for each color light.

It is a schematic block diagram which shows the projection type display apparatus concerning embodiment of this invention. It is a schematic front view which shows the structural example of a wavelength selective polarizing element. It is a front view which shows the structural example of a color separation synthetic | combination prism. It is a characteristic view which shows the incident angle dependence characteristic of a dichroic film | membrane. It is a front view which shows the effect | action with respect to the illumination light of a color separation synthetic | combination prism. It is a front view which shows the effect | action with respect to the projection light of a color separation synthetic | combination prism. It is a figure which shows XY plan view, YZ top view, and its sectional drawing as a structural example of the wavelength selective polarizing element of the modification 1. 10 is a cross-sectional view showing another configuration example of the wavelength selective polarizing element of Modification Example 1. FIG. It is a figure which shows together XY top view, YZ top view, and its sectional drawing as another example of a structure of the wavelength selective polarizing element of the modification 1. FIG. It is a schematic block diagram which shows the outline | summary of the projection type display apparatus shown by patent document 1. FIG. It is a schematic block diagram which shows the outline | summary of the projection display apparatus of the 2 chip | tip system shown by the nonpatent literature 1. It is a schematic block diagram which shows the outline | summary of the projection display apparatus of the 3 chip | tip system shown by the nonpatent literature 1. It is a schematic plan view which shows the outline | summary of the projection type display apparatus shown by patent document 2. FIG. FIG. 14 is a schematic side view of FIG. 13.

Explanation of symbols

3,3A Wavelength selective polarizing element 6G, 6RB DMD element 7 Projection lens 10 Color separation / combination prism 11, 12 Prism 13 Prism joint surface 14 Dichroic film

Claims (9)

A projection display device comprising: a plurality of reflective spatial light modulators that modulate color light based on a color signal; a filter member that selectively converts the polarization direction of illumination light; and a projection lens.
Polarized light of each color wavelength range depending on the difference in incident angle between the first incident angle and the second incident angle on the joint surface of the first and second prism elements, which is composed of first and second prism elements. A color separation / combination prism having a dichroic film whose transmission and reflection characteristics are determined, and the illumination light having passed through the filter member is incident on the dichroic film at the first incident angle and separated into a plurality of color lights by the dichroic film. Then, each separated color light is guided to the corresponding reflective spatial light modulator for the corresponding color light, and a plurality of color lights emitted after being modulated by the plurality of reflective spatial light modulators are applied to the second dichroic film. A projection type display device characterized in that it is made incident at an incident angle of, and is color-combined by the dichroic film and emitted toward the projection lens.   The projection display device according to claim 1, wherein the dichroic film has different characteristics in wavelength regions to be transmitted and reflected in accordance with an incident angle.   The projection display device according to claim 2, wherein the dichroic film has a characteristic that a wavelength region transmitted and reflected is shifted in accordance with an incident angle. The first prism element includes a first surface portion on which the illumination light is incident, emission of illumination light to the first reflective spatial light modulator, and modulation from the first reflective spatial light modulator. A second surface portion that allows both incident light to pass through,
The second prism element allows a third light to pass through both the emission of illumination light to the second reflective spatial light modulator and the incidence of modulated light from the second reflective spatial light modulator. 4. The projection display device according to claim 1, further comprising: a fourth surface portion that transmits the modulated light that is color-combined and travels toward the screen. 5.   The first prism element has a shape in which a triangle can be defined by the first surface portion, the second surface portion, and the joint surface, and the second prism element is formed by the third surface portion. The projection display device according to claim 4, wherein a triangle can be defined by the fourth surface portion and the joint surface.   The projection display device according to claim 1, wherein each of the first and second prism elements has a triangular prism shape.   7. The optical path from the dichroic film to each of the reflective spatial light modulators and the optical path from each of the reflective spatial light modulators to the dichroic film do not have a reflective surface. The projection display device according to one.   8. The modulated light emitted from the modulation surface of each reflective spatial light modulator and directed to the screen is emitted in a direction perpendicular to the top surface of the reflective spatial light modulator. The projection display device according to any one of the above.   The reflective spatial light modulator includes a reflective spatial light modulator for one of the three primary colors and a reflective spatial light modulator that shares the remaining two of the three primary colors in a time-sharing manner. The projection display device according to claim 1, wherein the projection display device is a two-plate type.

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