JP2010026403A - Polarized light converter and image projector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarized light converter always projecting two color light rays without arranging an optical element on a single focusing point on an optical path, and to provide an image projector using the polarized light converter. <P>SOLUTION: The polarized light converter includes: a first polarized light conversion member (7a) on which a first wavelength selection polarized light conversion element (15a) having a predetermined width for turning the polarized direction of green light by 90 degrees and a predetermined distance equal to the width and a second wavelength selection polarized light conversion member (15b) having a predetermined width for turning the polarized direction of blue light by 90 degrees and a predetermined distance are arranged alternately in the optical axis direction; and a second polarized light conversion member (7b) arranged facing the first polarized light conversion member (7a) and on which a first wavelength selection polarized light conversion element (15c) having a predetermined width and a predetermined distance, and a second wavelength selection polarized light conversion element (15d) having a predetermined width and a predetermined distance, are arranged in the same position in the optical axis direction, wherein the first polarized light conversion member (7a) and the second polarized light conversion member (7b) are relatively and reciprocally moved to shift the relative positions by a predetermined width. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarization conversion device and an image projection device that uses this to enlarge and project an image on a screen.

  Conventionally, as an image projection apparatus, for example, light of three primary colors of red (R), green (G), and blue (B) from a light source is divided into groups of two color lights, and the color lights of these two groups are sometimes used. In addition to sequentially switching in the division, by changing the polarization direction of the color light common to the two groups and the other color light, the optical path of the two colors of color light of each group is separated using the difference in polarization direction, There is known an image projection apparatus that modulates and projects each separated light with an image modulation element (see, for example, Patent Documents 1-3).

  FIG. 10 shows a reflection type image projection apparatus described in Patent Document 1. As shown in FIG. In this reflection type image projection apparatus, white light from a light source 101 composed of a high-pressure mercury lamp (UHP) is collected by an elliptical mirror 102 and enters a glass rod 104 through a color wheel 103. As shown in FIG. 11, the color wheel 103 includes a region 103a that transmits cyan (light including B and G components) light and a region 103b that transmits magenta (light including B and R components) light. It is comprised. The light incident on the glass rod 104 in FIG. 10 enters the polarizing plate 107 as substantially parallel light via the illumination lens 105 and the field lens 106, and polarization control is performed as polarized light having only a component perpendicular to the paper surface. Incident on the element 108. As shown in FIG. 12, the polarization control element 108 rotates the polarization direction of only the B component of the incident light in the direction parallel to the paper surface and makes it incident on the polarization beam splitter (PBS) 109. As shown in FIG. 13, since the B polarization component is P-polarized light, it passes through the PBS 109, and the R and G components are S-polarized light and is reflected by the PBS 109. The light transmitted / reflected through the PBS 109 is modulated by the image signal by the corresponding reflective liquid crystal elements 110-1 and 110-2 shown in FIG. , Projected onto a screen (not shown).

With such a configuration, in the image projection apparatus described in Patent Document 1, by rotating the color wheel 103, the color light transmitted through the color wheel 103 is switched in time division between the two color lights of cyan and magenta. I have to. As a result, as a whole apparatus, the conventional three-color optical paths of R, G, and B are separated, modulated by three image modulation elements, and further color-combined and projected onto a screen. Rather than this, the overall configuration of the apparatus can be simplified, and an inexpensive and small apparatus can be provided. In addition, compared with the case where each color light of R, G, and B is switched by time division for each color, since the components of two colors are always projected, a brighter projected image can be obtained.
Japanese Patent No. 3522591 Japanese Patent No. 3571582 Japanese Patent No. 3618611

  However, in this method, since the color wheel is arranged at the position where the light from the light source is collected, the energy of the white light emitted from the light source is concentrated on the color wheel, and the color wheel may be damaged by heat. There is. As a method for solving such a problem, for example, as shown in FIG. 14, it is conceivable to arrange the color wheel 103 on a parallel optical path between the field lens 106 and the polarizing plate 107. However, in this case, the color wheel becomes large, and as a result, there arises a problem that the entire apparatus becomes large and the price becomes high.

  Therefore, an object of the present invention made by paying attention to these points is to always project two colored lights and display a bright image without arranging an optical element at a single condensing point on the optical path. An object of the present invention is to provide a polarization conversion device that can be used, and a small and inexpensive image projection device using the polarization conversion device.

  The invention of the polarization conversion device according to claim 1, which achieves the above object, has a predetermined width for rotating the polarization direction of light having the first wavelength by 90 degrees and a predetermined interval substantially equal to the predetermined width. 1 wavelength-selective polarization conversion element and a second wavelength-selective polarization conversion element having the predetermined width and the predetermined interval for rotating the polarization direction of light having the second wavelength by 90 degrees, First polarization conversion members arranged alternately when viewed in the direction, and the first wavelength selective polarization conversion disposed opposite to the first polarization conversion member and having the predetermined width and the predetermined interval An element, and a second polarization conversion member in which the second wavelength selective polarization conversion element having the predetermined width and the predetermined interval is disposed at the same position when viewed in the optical axis direction, Relative position of the first polarization conversion member and the second polarization conversion member The first polarization conversion member and the second polarization conversion member are relatively reciprocated so as to be shifted by the predetermined width, whereby the polarization direction of the light having the first wavelength and the first The polarization direction of the light having the wavelength of 2 is orthogonal to each other and is sequentially rotated by 90 degrees.

  The invention of the image projection device according to claim 2, which achieves the above object, includes a light source that emits illumination light including light having a first wavelength, light having a second wavelength, and light having a third wavelength; The two reflection type display elements that modulate and reflect the illumination light from the light source based on the image signal, and the illumination light from the light source is separated and incident on the two reflection type display elements. An image projection apparatus configured to project the modulated light synthesized by the light separating and synthesizing means, the light separating and synthesizing means for synthesizing the modulated light modulated by the two reflective display elements. A first wavelength-selective polarization conversion provided with a separation / synthesis unit and having a predetermined width for rotating the polarization direction of the light having the first wavelength by 90 degrees and a predetermined interval substantially equal to the predetermined width; An element, and the second wavelength First polarization conversion members in which the second wavelength-selective polarization conversion elements having the predetermined width and the predetermined interval for rotating the polarization direction of the light to be rotated are alternately arranged as viewed in the optical axis direction; The first wavelength-selective polarization conversion element disposed opposite to the first polarization conversion member and having the predetermined width and the predetermined interval, and the first wavelength selective polarization conversion element having the predetermined width and the predetermined interval A polarization conversion device including a second polarization conversion member in which two wavelength-selective polarization conversion elements are arranged at the same position when viewed in the optical axis direction, the first polarization conversion member, and the second polarization conversion member The first polarization conversion member and the second polarization conversion member are reciprocally moved relative to each other so as to shift the relative position with respect to the predetermined width, thereby polarizing light having the first wavelength. The direction and the polarization direction of the light having the second wavelength are orthogonalized. Drive means for sequentially rotating 90 degrees, and a filter provided between the light separating / combining means and one of the two reflective display elements and transmitting only light having the third wavelength. In synchronization with the relative reciprocation of the first polarization conversion member and the second polarization conversion member by the driving unit, the light separation / synthesis unit converts the first polarization conversion member to one of the two reflective display elements. Makes the light having the third wavelength incident through the filter, and selects the light having the first wavelength or the light having the second wavelength as the other of the two reflective display elements. The modulated light of the light having the first wavelength and the modulated light of the light having the third wavelength, or the modulated light of the light having the second wavelength and the third wavelength. It is configured to synthesize and project the modulated light of the light it has It is characterized by that.

  A third aspect of the present invention is the image projection apparatus according to the second aspect, wherein the light beam incident from the light source is reflected by an inner surface and emitted between the light source and the light separating / combining means. And a lens system arranged so as to form a plurality of light source images on the same plane by a light beam emitted from the rod integrator, and the first polarization conversion member and the second polarization conversion. The member is arranged in the vicinity of the plane including the plurality of light source images.

  According to a fourth aspect of the present invention, in the image projection apparatus according to the second aspect, a fly-eye lens that divides a light beam incident from the light source into a plurality of light beams between the light source and the light separation / synthesis unit. The polarization conversion means for aligning the polarization directions of the plurality of light beams emitted from the fly-eye lens, and the plurality of light beams converted by the polarization conversion means form a plurality of light source images on the same plane. The lens system further includes an arranged lens system, and the first polarization conversion member and the second polarization conversion member are arranged in the vicinity of the plane including the plurality of light source images.

  According to a fifth aspect of the present invention, there is provided the image projection apparatus according to any one of the second to fourth aspects, wherein two of the light separating / combining means and the two reflective display elements are arranged. A quarter-wave plate is provided, the light separating / combining means is a polarization beam splitter, and the two reflective display elements are constituted by a mirror array, and a reflection for displaying an image by tilting a mirror of the mirror array. It is a type | mold display element, It is characterized by the above-mentioned.

  According to the present invention, the first polarization conversion member and the second polarization conversion member are relatively moved so that the relative positions of the first polarization conversion member and the second polarization conversion member are shifted by a predetermined width. By reciprocating, the polarization direction of the light having the first wavelength and the polarization direction of the light having the second wavelength are rotated 90 degrees in order orthogonal to each other. By means of the light separating / combining means, light having the third wavelength is incident on one of the two reflective display elements through a filter, and the other has light having the first wavelength or second wavelength. The light is selectively incident, and the modulated light of the light having the first wavelength and the modulated light of the light having the third wavelength, or the modulated light of the light having the second wavelength and the third wavelength By combining and projecting the modulated light of the light, a single condensing point on the optical path Provided is a polarization conversion device capable of projecting two colored lights in order and displaying a bright image without arranging any scientific elements, and a small and inexpensive image projection device using this polarization conversion device can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram of an image projection apparatus according to a first embodiment of the present invention.

  In the present embodiment, a white light source such as a xenon lamp is used as the lamp 1 of the illumination light source, and an elliptical reflecting surface that reflects light from the lamp 1 on the back surface and collects the light on the optical axis is provided. A reflector 2 is arranged. Further, the rod integrator 3 is arranged so that the light incident surface coincides with the condensing point of the reflected light from the reflector 2. The rod integrator 3 is for making the illuminance of the display image uniform, has a shape of a rectangular column that is long in the direction of the optical axis, and reflects and transmits light on the inner surface thereof. On the exit side of the rod integrator 3, an exit lens 4, a superposition lens 5, a polarizing plate 6, and two polarization conversion members 7 a and 7 b constituting a polarization conversion device are arranged in order, and light emitted from the rod integrator 3. Is configured such that the light beam is expanded through the exit lens 4 and the superimposing lens 5 and then incident on the polarizing plate 6. Further, the polarizing plate 6 is configured to transmit only light in a direction perpendicular to the paper surface and to enter the polarization conversion member 7a.

  FIG. 2 is a perspective view of the polarization conversion members 7a and 7b constituting the polarization conversion device. The polarization conversion member 7a has, for example, a plurality of wavelength-selective polarization conversion elements 15a having a width of 100 μm arranged on the surface on the incident side of the transparent substrate 14a at intervals of 100 μm in parallel with each other, The plurality of wavelength selective polarization conversion elements 15b are arranged so that the wavelength selective polarization conversion elements 15b are positioned between the adjacent wavelength selective polarization conversion elements 15a on the incident side. The polarization conversion member 7b has a plurality of wavelength-selective polarization conversion elements 15c having a width of 100 μm, for example, arranged parallel to each other at an interval of 100 μm on the incident-side surface of the transparent substrate 14b, and on the emission-side surface. Is configured by arranging a plurality of wavelength selective polarization conversion elements 15d so as to overlap with the wavelength selective polarization conversion elements 15c on the incident side.

  Further, the polarization changing members 7a and 7b are disposed adjacent to each other so that the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d are parallel to each other.

  The wavelength selective polarization conversion elements 15a and 15c provided on the incident sides of the polarization conversion members 7a and 7b rotate the polarization direction of only green light, which is light having the first wavelength, by 90 degrees. Further, the wavelength selective polarization conversion elements 15b and 15d provided on the emission side rotate the polarization direction of only blue light which is light having the second wavelength by 90 degrees. In the present embodiment, the direction of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d in FIG. 1 is perpendicular to the paper surface.

  Further, in FIG. 1, a PBS 8 that has a characteristic of reflecting S-polarized light and transmitting P-polarized light and constituting a light separating / combining means is provided on the exit side of the polarization conversion member 7b. In addition, a field lens 9a and a λ / 4 plate 11a are provided in this order on the optical path of the illumination light transmitted through the PBS 8, and the illumination light from the lamp 1 is a reflection type display element such as a digital micromirror device (DMD) 12a. It is comprised so that it may irradiate.

  Further, on the optical path of the illumination light reflected by the PBS 8, a field lens 9b, a band pass filter (BPF) 10 that selectively transmits only red light, and a λ / 4 plate 11b are provided in order, and illumination from the lamp 1 is performed. The light is configured to irradiate DMD 12b.

  Further, the λ / 4 plate 11a and the field lens 9a are also located in the optical path of the modulated light reflected by the DMD 12a, and the modulated light transmitted through the λ / 4 plate 11a and the field lens 9a is incident on the PBS 8 again. Configured. The λ / 4 plate 11b, the BPF 10, and the field lens 9b are also positioned in the optical path of the modulated light reflected by the DMD 12b. The modulated light transmitted through the λ / 4 plate 11b, the BPF 10, and the field lens 9b is also PBS8. It is comprised so that it may inject into again. However, since the illumination light is transmitted through the BPF 10, the modulated light is red light. Therefore, the BPF 10 does not particularly act on the modulated light.

  Further, a projection lens 13 is provided on the reflection side of the modulated light from the DMD 12a incident on the PBS 8 by the PBS 8 and on the transmission side of the modulated light from the DMD 12b by the PBS 8, and the two modulated lights are illustrated in the figure. Do not focus on the screen.

  In the present embodiment, the illumination light from the lamp 1 is obliquely incident on the PBS 8 so that the modulated light reflected from the DMDs 12a and 12b is incident on the PBS 8 substantially perpendicularly. In the following drawings, except for FIG. 8, for the sake of simplicity, the optical path of the illumination light is not assumed to be inclined.

  FIG. 3 is an explanatory diagram showing optical paths of light of each color of green (G) light, blue (B) light, and red (R) light that is light having a third wavelength in this optical system. The subscripts s and p indicate that the polarization directions are S-polarized light and P-polarized light. The white light Ws polarized in the direction perpendicular to the paper surface by the polarizing plate 6 is incident on the polarization conversion members 7a and 7b. As described above, on the incident side of the polarization conversion members 7a and 7b, the wavelength selective polarization conversion elements 15a and 15c that rotate the polarization direction of only the light of the green wavelength component by 90 degrees are provided, and the blue side is provided on the emission side. Wavelength selective polarization conversion elements 15b and 15d that rotate the polarization direction by 90 degrees only for the light of the wavelength component are provided. When viewed in the optical axis direction, as described above, in the polarization conversion member 7a, these two wavelength-selective polarization conversion elements 15a and 15b are alternately arranged, and in the polarization conversion member 7b, these two wavelength-selective polarization conversions. Elements 15c and 15d are arranged to overlap at the same position. In this figure, the field lenses 9a and 9b are omitted for the sake of simplicity.

  Therefore, as shown in FIG. 3A, when the polarization conversion members 7a and 7b are arranged to face each other so that the wavelength selective polarization conversion elements 15a, 15c, and 15d are at the same height, When the blue component Bs of the light Ws is transmitted through the polarization conversion members 7a and 7b, the blue component Bs is transmitted through the wavelength selective polarization conversion elements 15b and 15d arranged at different positions, so that the polarization direction is rotated by 90 degrees and Bp Become. On the other hand, the green component Gs is sequentially transmitted through the wavelength selective polarization conversion elements 15a and 15c of the polarization conversion members 7a and 7b to return to the original polarization direction, and is transmitted through the wavelength selective polarization conversion element 15b of the polarization conversion member 7a. In doing so, the polarization direction is not changed because the polarization direction is not rotated. Moreover, since the polarization conversion members 7a and 7b do not act on the red component Rs, the polarization direction remains S-polarized light.

  Each color light Bp, Rs, Gs transmitted through the two polarization conversion members 7a, 7b is incident on the PBS 8. The blue light Bp composed of the P-polarized component passes through the PBS 8 and enters the DMD 12a through the λ / 4 plate 11a. The DMD 12a modulates the reflection direction based on the image signal, specifically, changes the tilt of the minute mirror according to ON / OFF of the pixel, and reflects this incident light. This reflected light is again transmitted through the λ / 4 plate 11a. By reciprocating twice through the λ / 4 plate 11a, the polarization direction of the blue light is rotated by 90 degrees and becomes S-polarized light and reflected by the PBS 8 toward the projection lens 13 shown in FIG. On the other hand, red light Rs and green light Gs composed of S-polarized components are reflected by the PBS 8 and enter the BPF 10. Here, the BPF 10 has a wavelength characteristic that transmits red light and does not transmit blue light and green light. Therefore, only the red light Rs passes through the BPF 10, passes through the λ / 4 wavelength plate 11b, is modulated and reflected by the DMD 12b based on the image signal, and passes through the λ / 4 wavelength plate 11b again. By reciprocating twice through the λ / 4 plate 11b, the polarization direction of the red light is rotated by 90 degrees, becomes P-polarized light, passes through the PBS 8, and exits toward the projection lens 13.

  On the other hand, the polarization conversion member 7b is moved downward so that the wavelength selective polarization conversion elements 15b, 15c and 15d are at the same height as shown in FIG. When 7b is opposed, the green component Gs of the white light Ws passes through the wavelength selective polarization conversion elements 15a and 15c arranged at different positions when passing through the polarization conversion members 7a and 7b. , The polarization direction of 90 degrees is rotated to Gp. On the other hand, the blue component Bs sequentially passes through the wavelength selective polarization conversion elements 15b and 15d of the polarization conversion members 7a and 7b to return to the original polarization direction, and transmits through the wavelength selective polarization conversion element 15a of the polarization change member 7a. In doing so, the polarization direction is not changed because the polarization direction is not rotated. Further, since the polarization conversion members 7a and 7b do not act on the red component Rs, the polarization direction remains Rs.

  For this reason, for each color light Gp, Rs, and Bs transmitted through the polarization conversion members 7a and 7b, in the case of FIG. 3A, the blue light and the green light are switched, and the DMD 12a is modulated by the image signal. The green light Gs and the red light Rp modulated by the image signal by the DMD 12 b are emitted in the direction of the projection lens 13 shown in FIG. 1, and the blue light Bs is blocked from being transmitted by the BPF 10.

  FIG. 4 is a block diagram showing a schematic configuration of a control system of the image projection apparatus shown in FIG. This control system includes a polarization conversion member 7b and a controller 16 for controlling the DMDs 12a and 12b. The controller 16 processes a red image processing circuit 17r, a blue image processing circuit 17b and a green image processing circuit 17g for processing an image signal for each color component, and a signal from the blue image processing circuit 17b and a signal from the green image processing circuit 17g. And an image switching circuit 18 for switching between.

  Further, the control system includes a driving driver 19 controlled by the controller 16 and an actuator 20 driven by the driving driver 19 as driving means for driving the polarization conversion member 7b. The display device driver 21a for driving the DMD 12a and the display device driver 21b for driving the DMD 12b are provided. The display element driver 21a receives the output signal of the blue pixel processing circuit 17b or the green pixel processing circuit 17g switched by the image switching circuit 18 and drives the DMD 12a. The display element driver 21b receives the output signal of the red pixel processing circuit 17r and drives the DMD 12b.

  In the present embodiment, a piezo element is used as the actuator 20 to drive the polarization conversion member 7b up and down. By using the piezo element in this way, it can be moved up and down at high speed and with high accuracy. Since the stroke of the piezo element is usually about a few tens of μm, it is suitable when the interval between the wavelength selective polarization conversion elements is about 100 μm. Also, since the piezo element has a fast response speed, the moving time for switching between FIG. 3 (a) and FIG. 3 (b) is shortened, and the stationary time of FIG. 3 (a) and FIG. 3 (b) is reduced. This makes it possible to shorten the time in which blue light and green light are mixed with a portion whose polarization direction is rotated and a portion that is not rotated, and can effectively prevent the occurrence of false colors. .

  With the configuration as described above, the white light emitted from the lamp 1 in FIG. 1 is reflected by the reflector 2, and passes through the rod integrator 3, the exit lens 4, the superposition lens 5, the polarizing plate 6, and the polarization conversion members 7a and 7b. Incident on PBS8.

  At this time, if the polarization conversion members 7a and 7b are at the relative positions shown in FIG. 3A, the blue light transmitted through the PBS 8 irradiates the DMD 12a through the field lens 9a and the λ / 4 plate 11a, and this DMD 12a. 4 is modulated and reflected by the output signal of the blue pixel processing circuit 17b of FIG. 4, and is reflected by the PBS 8 through the λ / 4 plate 11a and the field lens 9a, and then through the projection lens 13, and a desired image on a screen (not shown). Projects the blue component of. At the same time, the red light reflected by the PBS 8 irradiates the DMD 12b through the field lens 9b, the BPF 10, and the λ / 4 plate 11b, and is modulated and reflected by the DMD 12b by the output signal of the red pixel processing circuit 17r in FIG. Then, the PBS 8 is transmitted through the λ / 4 plate 11b, the BPF 10, and the field lens 9b, and the red component of the desired image is projected on the screen (not shown) through the projection lens 13.

  If the polarization conversion members 7a and 7b are at the relative positions shown in FIG. 3B, the green light transmitted through the PBS 8 irradiates the DMD 12a through the field lens 9a and the λ / 4 plate 11a, and the DMD 12a 4 is modulated and reflected by the output signal of the green pixel processing circuit 17b of FIG. 4, reflected by the PBS 8 through the λ / 4 plate 11a and the field lens 9a, and through the projection lens 13, and a desired image is reflected on the screen (not shown). Projects the green component. At the same time, the red light reflected by the PBS 8 irradiates the DMD 12b through the field lens 9b, the BPF 10, and the λ / 4 plate 11b, and is modulated and reflected by the DMD 12b by the output signal of the red pixel processing circuit 17r in FIG. Then, the PBS 8 is transmitted through the λ / 4 plate 11b, the BPF 10, and the field lens 9b, and the red component of the desired image is projected on the screen (not shown) through the projection lens 13.

  Then, the arrangement of the polarization conversion members 7a and 7b in FIG. 3A and the arrangement in FIG. 3B are controlled by the controller 16 in FIG. The controller 16 drives the actuator 20 by the driving driver 19 to repeatedly reciprocate the wavelength selective polarization conversion element 7b in the vertical direction, and the state shown in FIG. 3A and the state shown in FIG. And switch at high speed. Further, in synchronization with this switching, the image switching circuit 18 outputs the output signal of the blue image processing circuit 17b in the state of FIG. 3A, and the output of the green image processing circuit 17g in the state of FIG. 3B. The signal is transmitted to the display element driver 21a that drives the DMD 12a. On the other hand, the output signal from the red image processing circuit 17r is constantly transmitted to the display element driver 21b that drives the DMD 12b.

  In this way, image projection onto a screen (not shown) using two color lights of red and blue and red and green can be switched at high speed, and a desired projection image that is visually synthesized from the three primary colors red, green, and blue. Is obtained.

  As described above, in the present embodiment, the polarization conversion members 7a and 7b are arranged in the illumination light path that is not the condensing point, and the green light and the blue light are converted without changing the polarization of the red light. Polarized light is selectively converted so that an image is always projected with two colored lights. Therefore, the polarization conversion members 7a and 7b are not damaged by heat, and the polarization conversion members 7a and 7b need only have a cross-sectional size of the illumination light beam at the arrangement position. Can be provided. Further, the polarization conversion members 7a and 7b can be arranged at any position between the lamp 1 and the PBS 8 as long as the light beam is not narrowed down in the illumination optical path. The degree of freedom is great.

(Second Embodiment)
FIG. 5 is a diagram for explaining an optical system according to the second embodiment of the present invention. In the present embodiment, in the first embodiment, the arrangement of the polarization conversion members 7a and 7b is set to a predetermined position described below, and the widths and intervals of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d are set as follows. The actuator has a predetermined size described below, and the actuator is not a piezo element but a motor. FIG. 5 shows a schematic configuration of an illumination optical system from the lamp 1 to the DMDs 12a and 12b, and the PBS 8, the BPF 10, and the λ / 4 plates 11a and 11b are omitted for simplicity. Components not particularly described below are the same as those in the first embodiment.

  In FIG. 5, a primary light source image 22 is a plurality of primary light source images (virtual images) of the lamp 1 formed by the rod integrator 3 formed on the same plane 23. 2 is a secondary light source image (real image) of the lamp 1 formed on the same plane 25 by a lens system constituted by the combining lens 5. When the light from the lamp 1 passes through the rod integrator 3, it is reflected by the inner surface of the rod integrator, so that the primary light source image and the secondary light source image of the lamp 1 are arranged at substantially equal intervals vertically and horizontally. It is a lattice point. In the present embodiment, the polarizing plate 6 is disposed between the overlapping lens 5 and the secondary light source image 24, and the polarization conversion members 7a and 7b substantially coincide with the plane 25 on which the secondary light source image 24 is formed. Arrange to do. In FIG. 5, the polarization conversion members 7a and 7b are arranged so as to sandwich the plane 25. However, if the two are close to each other, the polarization conversion members 7a and 7b are both arranged on the incident side or the emission side of the plane 25. You may do it. Thus, even if the polarization conversion members 7a and 7b are arranged in the vicinity of the secondary light source image 24, there are a plurality of condensing points, for example, 25 in a 5 × 5 grid, so the light amount per point. And the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d are prevented from being damaged.

  The light exit surface of the rod integrator 3 has a conjugate relationship with the reflection surfaces of the DMD 12a and DMD 12b by using the exit lens 4, the overlapping lens 5, and the field lenses 9a and 9b. In the present embodiment, the reflecting surfaces of the DMDs 12a and 12b are, for example, a square with a side length of 10 mm, and the opening width of the rod integrator 3 is, for example, 3 mm.

  In this configuration, the lattice spacing of the primary light source image 22 formed on the plane 23 including the light incident surface of the rod integrator 3 is equal to the opening width of the rod integrator 3. Further, the magnification of the secondary light source image 24 with respect to the primary light source image 22 determined by the exit lens 4 and the overlapping lens 5 is set to 1 so that the interval between the secondary light source images 24 is equal to the interval between the primary light source images 22. Thus, the lattice spacing of the secondary light source image (real image) is also made equal to the opening width of the rod integrator 3.

  FIG. 6 is a diagram for explaining the arrangement of the polarization conversion members 7a and 7b and the widths and intervals of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d. FIG. 6A is a plan view of the secondary light source image 24 and the polarization conversion member 7a viewed in the direction along the optical path of the illumination light. FIG. 6B is a side view of the polarization conversion members 7a and 7b viewed from the same height position as FIG. 6A. As described above, the secondary light source image 24 of the lamp 1 has a two-dimensional lattice point shape. Therefore, the widths and intervals of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d of the polarization conversion members 7a and 7b are made equal to the intervals of the respective light source images of the secondary light source image 24, and the amount of movement of the polarization conversion member 7b. The amount of movement in the vertical direction in FIG. 6 is also set to the same size. The polarization conversion members 7a and 7b are in the state shown in FIGS. 3A and 3B, and each light source image 24 is in the center of the width of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d. Try to be in the vicinity.

  From the above, the width and interval of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d are 3 mm in the present embodiment. For this reason, since the amount of movement is large and cannot be handled by a piezo element, the actuator 20 in FIG. 4 uses a motor instead of a piezo element.

  With the configuration as described above, in the present embodiment, similarly to the first embodiment, the polarization conversion member 7b is driven to provide the polarization conversion provided with the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d. The members 7a and 7b are relatively moved to sequentially switch the polarization directions of the blue light and the green light of the illumination light emitted from the lamp 1. At this time, since the secondary light source image 24 from the lamp 1 is a point image in the present embodiment, the wavelength selective polarization conversion elements 15c and 15d convert the point image of this light source with the movement of the polarization conversion member 7b. The time required to cross is short, that is, the polarization direction rotates in a short time. Thereby, about blue light and green light, the time when the part with which the polarization direction is rotating and the part which is not rotating can be shortened, and generation | occurrence | production of a false color can be prevented effectively. Other operations are the same as those in the first embodiment.

  As described above, according to the present embodiment, since the polarization conversion members 7a and 7b are arranged so as to substantially coincide with the plane 25 on which the secondary light source image 24 is formed, compared with the first embodiment, The effect similar to 1st Embodiment can be acquired, making the width | variety and space | interval of the wavelength selective polarization conversion element 15a, 15b, 15c, 15d wide. In addition, since the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d have a wide width and interval, it is easy to manufacture the polarization conversion members 7a and 7b, and an inexpensive motor is used instead of an expensive piezo element as an actuator. Since it can be used and fine accuracy of about 100 μm is not required as in the first embodiment, it is possible to manufacture the device more easily.

(Third embodiment)
FIG. 7 is a diagram for explaining an optical system according to the third embodiment of the present invention. In the second embodiment, the configuration on the incident side of the polarization conversion members 7a and 7b is changed to a configuration using a fly-eye lens in the second embodiment. FIG. 7 shows a schematic configuration of an illumination optical system from the lamp 1 to the DMDs 12a and 12b, and components not particularly described below are the same as those in the second embodiment.

  In this embodiment, instead of the reflector 2, the rod integrator 3, the exit lens 4, the overlapping lens 5, and the polarizing plate 6 of the second embodiment, the light from the lamp 1 is reflected so as to be substantially parallel light. Reflector 2, fly-eye lens 31, fly-eye lens 34 that is incident after each light beam refracted by fly-eye lens 31 is condensed so as to form primary light source image 32 on the same plane 33, and this fly-eye lens PS polarized light separating / converting element 35 for separating light emitted from 34 into two light of P polarized light and S polarized light, and a λ / 2 plate 36 for converting P polarized light emitted from PS polarized light separating / converting element 35 into S polarized light , And a fly-eye lens 37 that is a lens system for condensing the light emitted from the λ / 2 plate onto the secondary light source image 39. This configuration is used to make the illuminance of the display image uniform, similar to the rod integrator 3 of FIG. Further, the PS polarization separation conversion element 35 and the λ / 2 plate 36 constitute a polarization conversion means. Also in the present embodiment, similarly to the second embodiment, the polarization conversion members 7a and 7b are arranged so as to substantially coincide with the plane 39 on which the secondary light source image 38 is formed. In FIG. 7, the polarization conversion members 7a and 7b are arranged so as to sandwich the plane 39. However, if the two are close to each other, the polarization conversion members 7a and 7b are both arranged on the incident side or the emission side of the plane 39. You may do it.

  Further, the interval between the light source images formed by the light emitted from the lamp 1 in the secondary light source image 38 is determined by the lens arrangement of the fly-eye lens. Similar to the second embodiment, the widths and intervals of the wavelength selective polarization conversion elements 15a, 15b, 15c, 15d of the polarization conversion members 7a, 7b are set to the same values as the intervals of the respective light source images of the secondary light source image 38. To be. Therefore, in the present embodiment, the widths and intervals of the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d are determined by the arrangement of the fly-eye lenses.

  Next, the operation of this embodiment will be described. The white light emitted from the lamp 1 in FIG. 1 is reflected by the reflector 2 to become substantially parallel light, and the optical path is divided by a pair of fly-eye lenses 31 and 34. The divided white light is separated into P-polarized light and S-polarized light by the PS polarized light separating element, and further, the P polarized light passes through the λ / 2 plate 36 and becomes S-polarized light. The light passes through the fly-eye lens 37 in parallel with the emitted S-polarized light, and enters the polarization conversion members 7 a and 7 b in the vicinity of the secondary light source image 38. At this time, as described above, the incident light is only S-polarized light by the PS polarization separation / conversion element 35 and the λ / 2 plate 36. Therefore, the polarizing plate 6 is not required in this embodiment. The operation after the illumination light is incident on the polarization conversion members 7a and 7b is the same as that of the second embodiment.

  In the present embodiment, since the secondary light source image 38 from the lamp 1 is a point image as in the second embodiment, the wavelength selective polarization conversion elements 15a, 15b, 15c, and 15d are the light source of this light source. The time required to cross the point image is short, that is, the polarization direction rotates in a short time. Thereby, in blue light and green light, it is possible to shorten the time in which the portion where the polarization direction is rotated and the portion where the polarization direction is not rotated, and to effectively prevent generation of false colors.

  As described above, according to the present embodiment, since the polarization conversion members 7a and 7b are arranged so as to substantially coincide with the plane 39 on which the secondary light source image 38 is formed, the wavelength selective polarization conversion element 15a, Generation of false colors can be prevented while increasing the widths and intervals of 15b, 15c, and 15d, and the same effect as in the second embodiment can be obtained.

(Fourth embodiment)
FIG. 8 is a schematic diagram of an image projection apparatus according to the fourth embodiment of the present invention. In the first embodiment, the polarizing plate 6 is a polarizing plate that transmits only S-polarized light, whereas the polarizing plate 6 of the present embodiment is a polarizing plate that transmits only P-polarized light. Further, in place of the PBS 8 of the first embodiment, the color separation / combination prism 41 is disposed, and the BPF 10 and the λ / 4 plates 11a and 11b are not provided. Other configurations are the same as those of the first embodiment, and the same operations as those of the first embodiment are performed unless otherwise specified.

  Here, the color separation / combination prism 41 is formed by joining inclined surfaces of two right-angle prisms, and providing a dichroic film 42 and a polarization composition film 43 on the joint surfaces so as not to overlap each other. As shown in FIG. 8, using the inclination of the optical axis of the illumination light with respect to the color separation / combination prism 41, the illumination light to the DMDs 12a and 12b is transmitted or reflected through the dichroic film 42 in the color separation / combination prism 41, The dichroic film 42 and the polarization composition film 43 are arranged so that the modulated light reflected by the DMDs 12 a and 12 b is transmitted or reflected by the polarization composition film 43. Here, the dichroic film 42 has characteristics of reflecting red light and transmitting blue light and green light. Also. The polarization combining film 43 has a characteristic of reflecting S-polarized light and transmitting P-polarized light.

  Next, the operation of this embodiment will be described. The light emitted from the lamp 1 is reflected by the reflector 2 in the same manner as in the first embodiment, enters the polarizing plate 6 through the rod integrator 3, the outgoing lens 4, and the overlapping lens 5, and passes through the polarizing plate 6. The light becomes P-polarized light and enters the polarization conversion member 7a.

  FIG. 9 is an explanatory diagram showing the relationship between the arrangement of the polarization conversion members 7a and 7b and the polarization direction of each color light of red (R), green (G), and blue (B). In FIG. 9, when the polarization conversion members 7a and 7b are in the state shown in FIG. 9 (a), the incident white light of P-polarized light has a polarization direction of 90 as in the case of FIG. 3 (a). In this case, it is emitted as S-polarized light, and the polarization directions of the emitted light of red light and green light remain P-polarized light. On the other hand, when the polarization conversion members 7a and 7b are in the state shown in FIG. 9B, only the green light is rotated by 90 degrees in the polarization direction as in the case of FIG. In this case, the light is emitted as S-polarized light, and the polarization direction of the emitted light of red light and blue light remains P-polarized.

  The image switching circuit 18 in FIG. 4 transmits the output signal of the blue pixel processing circuit 17b to the display element driver 21a in the configuration of FIG. 9A, and the green pixel processing circuit 17g in the configuration of FIG. 9B. The output signal is controlled to be transmitted to the display element driver 21b.

  When the polarization conversion members 7a and 7b are in the state shown in FIG. 9A, the illumination light emitted from the polarization conversion member 7b enters the color separation / combination prism 41 shown in FIG. Of this illumination light, blue light and green light are transmitted through the dichroic film 42 and illuminate the DMD 12a through the field lens 9a. The DMD 12a is modulated and reflected by the output signal of the blue pixel processing circuit 17b in FIG. Then, the light enters the polarization combining film 43 of the color separation / combination prism 41 through the field lens 9a. In this polarization composition film 43, the P-polarized green light is transmitted, and only the S-polarized blue light is reflected, and the blue component of the desired image is projected on the screen (not shown) through the projection lens 13. Also, red light out of the illumination light incident on the color separation / combination prism 41 is reflected by the dichroic film 42, irradiates the DMD 12b through the field lens 9b, and the output signal of the red pixel processing circuit 17r in FIG. And is incident on the polarization combining film 43 of the color separation / combination prism 41 through the field lens 9b. In this polarization composition film 43, the P-polarized red light is transmitted, and the red component of the desired image is projected on the screen (not shown) through the projection lens 13.

  Next, when the polarization conversion members 7a and 7b are in the state shown in FIG. 9B, in the illumination light emitted from the polarization conversion member 7b, blue light becomes P-polarized light and green light becomes S-polarized light. In this case, in the state of FIG. 9A described above, the same operation as that in which the blue light and the green light are switched is performed. Therefore, in this case, a green component and a red color component of a desired image are projected on a screen (not shown).

  9A and 9B of the polarization conversion members 7a and 7b are switched at high speed under the control of the controller 16 in FIG. 4 as in the first embodiment. Therefore, the image projection onto a screen (not shown) using two color lights of red and blue and red and green can be switched at high speed, and a desired projection image obtained by visually combining the three primary colors of red, green and blue is obtained. It is done.

  As described above, in the present embodiment, since the color separation / combination prism 41 is provided to perform color separation of illumination light and color synthesis of modulated light, the BPF 10 and the λ / 4 plates 11a and 11b are not used. With a simpler configuration, the same effect as in the first embodiment can be obtained.

  In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible. For example, a digital micromirror device (DMD) is used as the reflective image display element, but other reflective image display elements, such as a reflective liquid crystal element, may be used.

  Further, in each of the above-described embodiments, only the polarization conversion member 7b positioned on the output side among the polarization conversion members 7a and 7b is driven. However, only the polarization conversion member 7a on the incident side may be driven. . Alternatively, both of the polarization conversion members 7a and 7b may be driven to obtain a relatively desired amount of parallel movement.

  Further, although the polarization conversion member rotates the polarization direction of blue light and green light, the polarization conversion member may rotate the polarization direction of blue light and red light or green light and red light. In this case, in the first embodiment, for example, in the first embodiment, it is necessary to change the characteristics of the bandpass filter 10 and the connection of the image switching circuit 18 of the controller 16 according to the combination of the color lights used.

  The light source is a white light source such as a xenon lamp, but another white lamp such as a high-pressure mercury lamp or a metal halide lamp may be used, and a white LED or white laser may be used.

1 is a schematic diagram of an image projection apparatus according to a first embodiment of the present invention. It is a perspective view of a polarization conversion member. It is explanatory drawing which shows the relationship between arrangement | positioning of a polarization conversion member, and the polarization direction of each color light of R, G, B. It is a block diagram which shows the outline of the control system of an image projector. It is explanatory drawing of the optical system which concerns on 2nd Embodiment of this invention. It is a figure explaining arrangement | positioning of a polarization conversion member, and the width | variety and space | interval of a wavelength selective polarization conversion element. It is explanatory drawing of the optical system which concerns on 3rd Embodiment of this invention. It is a schematic diagram of the image projector which concerns on 4th Embodiment of this invention. It is explanatory drawing which shows the relationship between arrangement | positioning of a polarization conversion member, and the polarization direction of each color light of R, G, B. It is a schematic diagram of the conventional image projector. It is explanatory drawing of the color wheel used for the conventional image projector. It is explanatory drawing of the function of the deflection | deviation control element used for the conventional image projector. It is explanatory drawing which shows the optical path of each color light which permeate | transmitted the deflection | deviation control element used for the conventional image projector. It is a schematic diagram of the image projector which has arrange | positioned the color wheel on a parallel optical path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lamp 2 Reflector 3 Rod integrator 4 Outgoing lens 5 Superposition lens 6 Polarizing plate 7a, 7b Polarization conversion member 8 Polarizing beam splitter (PBS)
9a Field lens 9b Field lens 10 Band pass filter (BPF)
11a, 11b λ / 4 plate 12a, 12b Digital micromirror device (DMD)
13 Projection lens 14a, 14b Transparent substrate 15a, 15b, 15c, 15d Wavelength selective polarization conversion element 16 Controller 17r Red pixel processing circuit 17g Blue pixel processing circuit 17b Green pixel processing circuit 18 Image switching circuit 19 Drive driver 20 Actuator 21a, 21b Display element driver 22 Primary light source image 23 Plane 24 Secondary light source image 25 Plane 31 Fly eye lens 32 Primary light source image 33 Plane 34 Fly eye lens 35 PS polarization separation conversion element 36 λ / 2 plate 37 Fly eye lens 38 2 Next light source image 39 Plane 41 Color separation / combination prism 42 Dichroic film 43 Polarization composition film 101 Light source 102 Ellipsoidal mirror 103 Color wheel 103a Area for transmitting cyan light 103b Area for transmitting magenta light 104 Glass rod 1 5 the illumination lens 106 field lens 107 polarizing plate 108 polarization control element 109 a polarization beam splitter (PBS)
110-1, 110-2, 110-3 Reflective liquid crystal display element 112 Polarization control element 113 Polarizing plate

Claims (5)

A first wavelength-selective polarization conversion element having a predetermined width for rotating the polarization direction of light having the first wavelength by 90 degrees, a predetermined interval substantially equal to the predetermined width, and light having the second wavelength First polarization conversion members in which the second wavelength-selective polarization conversion elements having the predetermined width and the predetermined interval for rotating the polarization direction are alternately arranged as viewed in the optical axis direction;
The first wavelength-selective polarization conversion element that is disposed to face the first polarization conversion member and has the predetermined width and the predetermined interval, and the predetermined width and the predetermined interval A second polarization conversion member disposed at the same position when viewed in the optical axis direction, the second wavelength selective polarization conversion element,
The first polarization conversion member and the second polarization conversion member are relatively moved such that the relative position between the first polarization conversion member and the second polarization conversion member is shifted by the predetermined width. Polarization conversion characterized in that the polarization direction of light having the first wavelength and the polarization direction of light having the second wavelength are orthogonally crossed and rotated sequentially by 90 degrees by reciprocating. apparatus. A light source that emits illumination light including light having a first wavelength, light having a second wavelength, and light having a third wavelength, and the illumination light from the light source is modulated and reflected based on an image signal Two reflective display elements and light separating / synthesizing means for separating the illumination light from the light source and making it incident on the two reflective display elements and combining the modulated light modulated by the two reflective display elements And projecting the modulated light synthesized by the light separating and synthesizing means,
A first width is provided between the light source and the light separating and combining unit, and has a predetermined width for rotating the polarization direction of the light having the first wavelength by 90 degrees and a predetermined interval substantially equal to the predetermined width. A wavelength-selective polarization conversion element, and a second wavelength-selective polarization conversion element having the predetermined width and the predetermined interval for rotating the polarization direction of the light having the second wavelength by 90 degrees. And the first wavelength-selective polarization conversion element disposed opposite to the first polarization conversion member and having the predetermined width and the predetermined interval. And a polarization conversion device comprising: a second polarization conversion member having the second wavelength-selective polarization conversion element having the predetermined width and the predetermined interval arranged at the same position when viewed in the optical axis direction;
The first polarization conversion member and the second polarization conversion member are relatively moved such that the relative position between the first polarization conversion member and the second polarization conversion member is shifted by the predetermined width. Driving means for reciprocally moving the optical axis so that the polarization direction of the light having the first wavelength and the polarization direction of the light having the second wavelength are orthogonal to each other, and sequentially rotating by 90 degrees;
A filter provided between the light separating / combining means and one of the two reflective display elements and transmitting only light having the third wavelength;
In synchronism with the relative reciprocation of the first polarization conversion member and the second polarization conversion member by the driving unit, the light separation / combination unit causes the one of the two reflective display elements to Light having the third wavelength is incident through a filter, and light having the first wavelength or light having the second wavelength is selectively incident on the other of the two reflective display elements. The modulated light of the light having the first wavelength and the modulated light of the light having the third wavelength, or the modulated light of the light having the second wavelength and the light having the third wavelength. An image projecting apparatus configured to synthesize and project modulated light.   Between the light source and the light separating and synthesizing means, a prismatic rod integrator that reflects and emits a light beam incident from the light source on an inner surface, and a plurality of light beams emitted from the rod integrator on the same plane. And a lens system arranged so as to form a light source image, wherein the first polarization conversion member and the second polarization conversion member are arranged in the vicinity of the plane including the plurality of light source images. The image projection apparatus according to claim 2.   A fly-eye lens that divides a light beam incident from the light source into a plurality of light beams between the light source and the light separation / combination unit, and a polarization conversion unit that aligns the polarization directions of the plurality of light beams emitted from the fly-eye lens. And a lens system arranged such that the plurality of light beams converted by the polarization conversion means form a plurality of light source images on the same plane, and the first polarization conversion member and the second The image projection apparatus according to claim 2, wherein the polarization conversion member is arranged in the vicinity of the plane including the plurality of light source images.   Two quarter-wave plates disposed between the light separating / combining means and each of the two reflective display elements, wherein the light separating / combining means is a polarization beam splitter, and the two reflective displays 5. The image projection apparatus according to claim 2, wherein the element is a mirror array, and is a reflective display element that displays an image by tilting a mirror of the mirror array.

Images