JP2007034102A - Rear projection type projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear projection type projector having an optical system suitable for miniaturization and thickness reduction. <P>SOLUTION: The rear projection type projector 100 includes a lamp 110, and a plurality of mirrors arranged in a matrix form, and each mirror includes a DMD 170 for making ON and OFF states by independently changing the tilt to change an outgoing angle of the reflected light, a projection lens 180 which makes the light reflected by the DND 170 incident and project, and 1st and 2nd reflecting mirrors 150, 160 arranged in an optical system between the lamp 110 and the DMD 170, and the 1st and the 2nd reflecting mirrors 150, 160 are at the positions holding an incident side main optical axis C3 of the projection lens 180 in-between. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projector capable of projecting an image such as a television or a DVD, and more particularly to a rear projection type projector.

  A projector that displays a color image using liquid crystal or DMD (Digital Micro-mirror Device) as a spatial modulation element has been put into practical use. In the DMD, each pixel arranged two-dimensionally is composed of a minute mirror, and the inclination of the minute mirror is controlled by an electrostatic field effect by a memory element arranged immediately below each pixel to change the reflection angle of reflected light. Thus, it is a reflective display element that creates an on / off state. When the pixel is off, the reflected light from the micro mirror of the pixel (hereinafter referred to as “off light”) does not enter the projection lens. When the pixel is in the on state, the reflected light from the micro mirror of the pixel (hereinafter referred to as “on light”) is projected. Optical components are arranged so as to enter the lens and form an image on the screen. The tilt angle of the on-light of the micromirror of each pixel is determined to be about 10 to 12 degrees with respect to the incident surface of the DMD light beam.

  Many proposals have been made for projectors using DMD. For example, Patent Document 1 discloses a color wheel, an illumination optical system using the same, and a projector, and Patent Document 2 discloses a DLP system using DMD. A projector is disclosed.

  As shown in FIG. 13, the light emitted from the lamp 10 is reflected by an elliptical mirror 12 that is a condensing mirror and is incident on a light tunnel or an optical integrator 14 that is an optical component. The light having a uniform light flux in the light tunnel 14 is incident on the color wheel 16. The color wheel 16 has R (red), G (green), and B (blue) color filters arranged on the circumference, and is rotated by a motor 16a. The light incident on the color wheel 16 is separated into R, G, and B, and the R, G, and B lights are the condenser lens 18, the folding plane mirror 20, the second folding spherical mirror 22, and the second. The DMD 26 is illuminated through the condenser lens 24. The reflected light (ON light) of the DMD 26 is incident on the projection lens 28, where it is magnified and projected on a screen.

JP2004-226545A JP 2003-241305 A

  FIG. 14 is a plan view showing the appearance of the rear projector. The rear projector 50 includes a projection display unit 52 that projects a color image, and an optical engine unit 54 that is attached to the lower part of the projection display unit 52. The optical engine unit 54 houses the optical system shown in FIG. However, this optical system is suitable for a projector having a front-projection type shift optical system in which the rotation axis of the reflective display element (DMD) is diagonal, and rotates around the short side or the long side as an axis. When applied to a rear projection type projector (rear projector) that uses a reflective display element, the height T, width W, or depth D of the optical engine unit 54 increases, and the rear projection type projector becomes smaller and thinner. Becomes difficult. This is because the optical system of FIG. 12 has the two folding mirrors 20 and 22 arranged on one side beyond the optical axis of the projection lens, so that the back focus of the projection lens 28 becomes longer, and the design of the wide-angle lens becomes easier. This makes it difficult to increase the number of constituent lenses, increase the lens aperture, reduce the transmittance, ghost, halation, and the like, making it difficult to reduce the size and causing an increase in cost.

SUMMARY An advantage of some aspects of the invention is that it provides a rear projection type projector having an optical system suitable for downsizing and thinning.
Another object of the present invention is to provide a rear projection type projector having an optical system suitable for high-resolution DMD.

  A rear projection type projector according to the present invention includes a light source and a plurality of matrix-arranged mirrors, and each mirror is changed to an on-state by changing an inclination angle by independently changing an inclination angle. A reflective display element that creates an off state, a projection lens that receives and projects light reflected by the reflective display element, and first and second mirrors disposed in an optical system between the light source and the reflective display element; The first and second mirrors are arranged at positions sandwiching the incident-side main optical axis of the projection lens.

  Preferably, the incident-side main optical axis of the projection lens is parallel to the outgoing angle of the reflected light of the mirror in the on state of the reflective display element. Further, the reflected light in the on state of the reflective display element enters the position of the pupil of the projection lens.

  The optical axis of the light source and the incident-side main optical axis of the projection lens are parallel or orthogonal. Alternatively, the relationship between the optical axis of the light source and the incident-side main optical axis of the projection lens may be less than 90 degrees.

  The aspect ratio of the reflective display element is 16: 9, for example. At this time, the rotation axis of the mirror changes the emission angle of the reflected light in the long side direction around the short side direction. Alternatively, the outgoing angle of the reflected light is changed in the short side direction with the long side direction as an axis. Preferably, the second mirror illuminates the reflective display element.

  A relay lens can be disposed between the light source and the first mirror. A color wheel in which color filters are arranged can be disposed between the light source and the first mirror. Light having a wavelength of at least red (R), green (G), and blue (B) is selected by the color wheel.

  A light tunnel or a light integrator can be disposed between the light source and the first mirror. A relay lens can be disposed between the first mirror and the second mirror. Further, a color wheel in which color filters are arranged can be disposed between the first mirror and the second mirror. A light tunnel or an optical integrator can be disposed between the first mirror and the second mirror.

  Preferably, the incident side main optical axis and the emission side optical axis of the projection lens have a constant angle. The exit side optical axis of the projection lens is parallel to the short side of the mirror of the reflective display element. The exit side optical axis of the projection lens may be a direction away from the optical axis of the light source, or may be a direction approaching the plateau optical axis.

  Preferably, the optical axes of the first and second mirrors are parallel to the short side of the reflective display element. The first and second mirrors can be either flat, spherical or aspherical. The first and second mirrors may be prisms. Further, the first and second mirrors may be cold mirror coated.

  According to the rear projection type projector of the present invention, in the optical system from the light source to the reflective display element, the first and second mirrors are arranged so as to sandwich the incident-side main optical axis of the projection lens. The back focus of the projector can be shortened, the degree of freedom of the layout of the projection lens and the light source is increased, and an optical system corresponding to the downsizing and thinning of the rear projector can be provided.

  The projector according to the present invention is preferably used in a DLP projector. Hereinafter, it will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an optical system of a rear projection type projector according to the first embodiment of the present invention. The projector 100 includes a lamp 110 with a condensing mirror, a color wheel 120, a light tunnel 130, a relay lens 140, a first folding mirror 150, a second folding mirror 160, a DMD 170, and a projection lens 180.

  The lamp 110 has a spheroid mirror 112 as a condensing mirror and a discharge lamp 114 attached in the optical axis direction C1. For example, a xenon lamp, a mercury lamp, a metal halide lamp, or the like can be used as the discharge lamp. The arc (light emitting point) of the discharge lamp 114 is condensed by the condensing mirror 112, and the color wheel 120 and the light tunnel 130 are arranged at a position where the condensed light converges.

  As is well known, the color wheel 120 rotates in which the annular zone is divided into the three primary colors of light (red (R), green (G), blue (B), or red, green, blue, white (W)). Includes possible filters. Light from the lamp 110 is incident on the color filter substantially perpendicularly, and R, G, and B light are sequentially emitted from the color wheel 120.

  In the vicinity of the color wheel 120, a light tunnel 130 is disposed along the optical axis C1 of the lamp 110. The R, G, and B light emitted from the color wheel 120 is incident on the light tunnel 130, where the intensity is uniformed and emitted from the end portion.

  The relay lens 140 includes a plano-convex lens L 1, a combination lens L 2, and a biconvex lens L 3, and these lenses are disposed on the optical axis C 1 of the lamp 110. The light beam emitted from the light tunnel 130 enters the first mirror folding mirror 150 via the relay lens 140.

  The first folding mirror 150 is, for example, a plane mirror. The second folding mirror 160 is arranged at a position facing the first folding mirror 150, in other words, with the incident-side main optical axis C3 of the projection lens 180 interposed therebetween. The optical axis C2 of the first folding mirror 150 and the second folding mirror 160 does not cross the optical axis C1 of the lamp and intersects at an angle slightly smaller than 90 degrees. The second folding mirror 160 is, for example, a spherical or aspherical mirror, and the light reflected there illuminates the matrix-like mirror element region of the DMD 170. The first folding mirror 150 may be a spherical or aspherical mirror, the second folding mirror 160 may be a plane mirror, and both the first and second folding mirrors 150 and 160 may be a plane mirror, spherical or non-spherical. A spherical mirror may be used.

  DMD 170 includes a plurality of micromirrors arranged in a two-dimensional manner, and each mirror independently changes its inclination to change the exit angle of reflected light to create an on state and an off state. For example, the mirror has an aspect ratio of 16: 9 on the long side and the short side. Then, the mirror rotation axis changes the emission angle of the reflected light in the long side direction about the short side direction. The direction in which the reflected light of the mirror in the ON state of DMD 170 is emitted coincides with the incident-side main optical axis C3 of the projection lens 180. Preferably, the reflected light in the on state of DMD 170 is incident on the pupil position of projection lens 180. The light of the mirror in the off state is directed away from the optical axis C3 and is not incident on the projection lens 180.

  The projection lens 180 receives the light from the DMD 170 and expands it in the direction of the emission side optical axis C4. The emitted light is projected on the screen of the rear projector. The projection lens 180 can be mounted in an arbitrary direction of 360 degrees with the incident side main optical axis C3 as the center. FIG. 1 shows a first state in which the emission side optical axis C4 of the projection lens 180 is attached in a direction away from the lamp optical axis C1, but FIG. 2 shows the projection lens 180 with the optical axis C3 as the center. The second state is shown in which the optical axis C4 is rotated in the direction in which the optical axis C4 approaches the optical axis C1. Further, from the first state shown in FIG. 1, the direction of the projection lens 180 may be rotated by 90 degrees to enter the third state shown in FIG. Of course, as described above, the direction of the emission-side optical axis C4 of the projection lens 180 can be any direction of 360 degrees.

  Further, the optical axis C1 of the lamp and the incident-side main optical axis C3 of the projection lens 180 are parallel, but they may be orthogonal to each other. Of course, a relationship of crossing at an angle other than orthogonal may be used. For example, the lamp 110 to the relay lens 140 shown in FIG. 1 may be rotated 90 degrees so as to be perpendicular to the paper surface. In this case, of course, the angles of the first mirror 150 and the second mirror 160 are adjusted so that the light from the lamp 110 illuminates the DMD 170. Alternatively, the layout from the lamp 110 to the relay lens 140 shown in FIG.

  As described above, in this embodiment, the first and second mirrors 150 and 160 are arranged so as to sandwich the incident side main optical axis C3 of the projection lens 180, and the incident side main optical axis C3 of the projection lens 180 is disposed on the DMD 170. By making it intersect perpendicularly, the back focus of the projection lens 180 can be shortened, which increases the degree of freedom of the mounting position of the projection lens 180 and simplifies the design of the projection lens, which is required for the projector. It is possible to realize a layout according to the space saving.

  For example, the lamp 110 desirably has a horizontal optical axis C1. At this time, if the orientation of the projection lens 180 is attached to the first state shown in FIG. 1, the height is h1, and if attached to the second state shown in FIG. 2, the height is h2 (h1 < h2). As a result, as shown in FIG. 5A, the height T1 of the optical engine unit 56 of the rear projector can be made smaller than the height T (see FIG. 10) of the conventional optical engine unit 54 (see FIG. 10). T1 <T), the overall height of the rear projection type projector can be suppressed.

  Next, an optical system of the projector according to the second embodiment of the present invention is shown in FIG. The same number is attached | subjected about the same structure as the 1st Example. In the second embodiment, unlike the first embodiment, the optical axis C2 of the first folding mirror 150 and the second folding mirror 160 is orthogonal to the optical axis C1 of the lamp. Further, the color wheel 120 is attached not to the incident side of the light tunnel 130 but to the emission side of the light tunnel 130. An optical integrator may be used instead of the light tunnel 130.

  Next, FIG. 7 shows an optical system of a projector according to a third embodiment of the present invention. In the projector according to the third example, the first folding mirror 150 is disposed in the relay lens optical system. That is, a plano-convex lens L1, a combination lens L2, a first folding mirror 150, and a biconvex lens L3 are arranged in order from the exit end of the light tunnel 130. The first folding mirror 150 and the second folding mirror 160 straddle the incident-side main optical axis C3 of the projection lens 180, and the lens L3 is disposed on the optical axis C2 of the first and second folding mirrors 150 and 160. The optical axis C2 is inclined so as to approach the DMD 170 side.

  The first folding mirror 150 is a plane mirror, and the second folding mirror 160 is a spherical or aspherical mirror. However, the first folding mirror 150 is a spherical or aspherical mirror, and the second folding mirror 160 is used. May be a plane mirror, or both the first and second folding mirrors 150 and 160 may be plane mirrors, spherical or aspherical mirrors.

  Further, the first folding mirror 150 is disposed between the lens L2 and the lens L3, but may be located at a position other than this. That is, the lamp 110, the color wheel 120, the light tunnel 130, and the lenses L1, L2, and L3 can be disposed.

  For the first and second folding mirrors, a prism or the like can be used instead of the mirror. Furthermore, the optical axis C2 of the first and second folding mirrors may be orthogonal to the incident-side main optical axis C3 of the projection lens. The projection lens 180 can also be rotated around the incident-side main optical axis C3.

  Next, FIG. 8 shows an optical system of a projector according to a fourth embodiment of the present invention. In the projector according to the fourth embodiment, the optical system from the lamp 110 to the first folding mirror 150 is inverted 180 degrees with respect to the first folding mirror 180. That is, the reflection direction of the first folding mirror 150 is changed by 180 degrees by inverting the first folding mirror 150 by 180 degrees. In the case of such a layout, the projection lens 180 and the lamp 110 can be arranged relatively close to each other, so that the optical engine can be downsized.

  Next, FIG. 9 shows an optical system of a projector according to a fifth embodiment of the present invention. In the projector according to the fifth embodiment, the first and second folding mirrors 152 and 160 arranged with the incident-side main optical axis C3 of the projection lens 180 interposed therebetween are spherical or aspherical mirrors, respectively. Further, by providing a part of the function of the relay lens optical system to the first or second folding mirrors 152 and 160, the first and second folding mirrors sandwiching the incident-side main optical axis C3 of the projection lens are provided. In addition, other optical members are not provided. For example, the plane mirror and the convex lens can be replaced with a concave mirror. Thereby, an optical member can be reduced and cost reduction and compactization of an optical engine can be achieved.

  Next, an optical system of the projector according to the sixth embodiment of the present invention is shown in FIG. In the projector according to the sixth embodiment, the first folding mirror 150 is disposed between the lamp and the color wheel 120. The optical axis C1 of the lamp 110 is parallel to the incident-side main optical axis C3 of the projection lens 180. Between the first folding mirror 150 and the second folding mirror 160, the color wheel 120, the light tunnel 130, and the relay lens 140 are arranged. With such a layout, the width W of the optical engine unit 58 can be suppressed, and a table top type rear projection projector as shown in FIG. 5B can be provided.

  Next, the configuration of the optical system of the rear projector of the present invention is shown in FIG. As shown in the drawing, an inclined support portion 210 is installed at the bottom of a rectangular housing 200 of the rear projector, and an optical system including the optical system shown in FIGS. 1 to 10 of the present invention is provided on the support portion 210. An engine unit 220 is disposed. A flat mirror 230 is mounted in the housing 200, and light emitted from the projection lens 180 of the optical engine unit 220 is reflected by the flat mirror 230 to irradiate the screen 240 mounted on the front surface of the housing 200 from the back surface. By using the optical engine 220 of the present embodiment, the back focus can be shortened, so that the design of a wide-angle lens can be facilitated and the structure can be miniaturized. A design to make D thinner is possible.

  Next, FIG. 12 shows a schematic configuration of the DMD used in the optical system of the rear projector of the present invention. In the DMD 170 preferably applied to the present invention, the aspect ratio when the mirrors 172 are arranged in a matrix array is M: N (M and N are natural numbers, and M> N). The aspect ratio is 16: 9, for example. In such a DMD, as shown in FIG. 12B, the mirror 172 is rotated by a rotation shaft 174 parallel to the long side direction (lateral direction) to change the emission angle of the reflected light in the short side direction. Alternatively, as shown in FIG. 12C, the mirror 172 may be rotated by a rotation shaft 176 parallel to the short side direction (longitudinal direction) to change the emission angle of the reflected light in the long side direction. Good.

  Although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the specific embodiment, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

  For example, the combination of the relay lenses and the combination of the shapes of the reflecting surfaces of the first and second folding mirrors can be appropriately changed according to the design of the projector. Further, the angle formed by the incident-side main optical axis C3 and the emission-side optical axis C4 of the projection lens 180 can be appropriately changed according to the design of the projector. Furthermore, the light source is not limited to the discharge lamp, and an LED or a laser light source may be used.

  The projector on the rear projection side according to the present invention can be widely used as a display device, a display system, and a home theater for displaying images such as televisions and DVDs.

It is a figure which shows the optical system of the projector which concerns on the 1st Example of this invention. It is a figure which shows the modification of the projector which concerns on a 1st Example. It is a figure which shows the modification of the projector which concerns on a 1st Example. It is a figure which shows the modification of the projector which concerns on a 1st Example. 1 is a plan view showing an appearance of a rear projection type projector of the present invention. It is a figure which shows the optical system of the projector which concerns on the 2nd Example of this invention. It is a figure which shows the optical system of the projector which concerns on the 3rd Example of this invention. It is a figure which shows the optical system of the projector which concerns on the 4th Example of this invention. It is a figure which shows the optical system of the projector which concerns on the 5th Example of this invention. It is a figure which shows the optical system of the projector which concerns on the 6th Example of this invention. It is a figure which shows an example of the rear projector of this invention. It is a figure explaining schematic structure of DMD of this invention, The figure (a) is a top view which shows the whole DMD array, The figure (b) is a mirror rotated by the rotating shaft parallel to a long side direction. The figure explaining a state and the figure (c) are figures explaining the state in which a mirror is rotated by the rotating shaft parallel to a short side direction. It is a figure which shows the optical system of the conventional projector. It is a figure explaining the subject of the conventional rear projection type projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Projector 110: Lamp 112: Condensing mirror 114: Discharge lamp 120: Color wheel 130: Light tunnel 140: Relay lens 150: 1st folding mirror 160: 2nd folding mirror 170: DMD
180: projection lens 200: housing 210: support unit 220: optical engine 230: plane mirror 240: screen C1: optical axis of the lamp C2: optical axis of the first and second mirrors C3: incident side main optical axis of the projection lens C4: Output side optical axis of the projection lens

Claims (26)

A rear projection type projector,
A light source;
A reflective display element including a plurality of mirrors arranged in a matrix, each mirror independently changing the tilt and changing the emission angle of the reflected light to create an on state and an off state;
A projection lens that receives and projects the light reflected by the reflective display element;
Including first and second mirrors disposed in an optical system between the light source and the reflective display element,
The first and second mirrors are arranged at positions sandwiching the incident-side main optical axis of the projection lens.
Rear projection type projector. 2. The rear projection type projector according to claim 1, wherein an incident-side main optical axis of the projection lens is parallel to an emission angle of reflected light of a mirror in an on state of the reflective display element. The rear projection type projector according to claim 1, wherein reflected light in an on state of the reflective display element is incident on a pupil position of the projection lens. The rear projection type projector according to any one of claims 1 to 3, wherein the optical axis of the light source and the incident-side main optical axis of the projection lens are parallel to each other. The rear projection type projector according to any one of claims 1 to 3, wherein the optical axis of the light source and the incident-side main optical axis of the projection lens are orthogonal to each other. The rear projection type projector according to any one of claims 1 to 5, wherein an angle formed by the optical axis of the light source and the incident-side main optical axis of the projection lens is smaller than 90 degrees. 7. The rear projection type projector according to claim 1, wherein the reflection display element changes the emission angle of the reflected light in the long side direction about the rotation axis of the mirror about the short side direction. 7. The rear projection type projector according to claim 1, wherein the reflective display element changes the emission angle of the reflected light in the short side direction with the rotation axis of the mirror as the axis in the long side direction. The rear projection type projector according to any one of claims 1 to 8, wherein the second mirror illuminates the reflective display element. The rear projection type projector according to claim 1, wherein a relay lens is disposed between the light source and the first mirror. A color wheel in which color filters are arranged is arranged between the light source and the first mirror, and at least red (R), green (G), and blue (B) wavelengths of light are selected by the color wheel. The rear projection type projector according to any one of claims 1 to 10. The rear projection type projector according to claim 1, wherein a light tunnel or an optical integrator is disposed between the light source and the first mirror. The rear projection type projector according to any one of claims 1 to 8, wherein at least a part of the relay lens is disposed between the first mirror and the second mirror. A color wheel in which color filters are arranged is disposed between the first mirror and the second mirror, and light of at least red (R), green (G), and blue (B) wavelengths is selected by the color wheel. The rear projection type projector according to any one of claims 1 to 8. 9. The rear projection type projector according to claim 1, wherein a light tunnel or an optical integrator is disposed between the first mirror and the second mirror. The rear projection type projector according to any one of claims 1 to 15, wherein an incident-side main optical axis and an exit-side optical axis of the projection lens have a constant angle. The rear projection type projector according to claim 16, wherein an output side optical axis of the projection lens is parallel to a short side of the mirror of the reflective display element. The rear projection type projector according to claim 16 or 17, wherein an output side optical axis of the projection lens is a direction away from the optical axis of the light source. 18. The rear projection type projector according to claim 16, wherein an output side optical axis of the projection lens is a direction approaching an optical axis of the light source. The rear projection type projector according to any one of claims 1 to 19, wherein the optical axes of the first and second mirrors are parallel to the short side of the reflective display element. 21. The rear projection type projector according to claim 1, wherein the first and second mirrors are any one of a flat surface, a spherical surface, and an aspherical surface. The rear projection type projector according to any one of claims 1 to 21, wherein the first and second mirrors include prisms. The rear projection type projector according to any one of claims 1 to 22, wherein the first and second mirrors are cold mirror coated. The reflective display element has an aspect ratio of M: N (M and N are natural numbers, M> N), and each mirror rotates about the long side direction of the reflective display element array. 23. A rear projection type projector according to any one of 23. The reflective display element has an aspect ratio of M: N (M and N are natural numbers and M> N), and each mirror rotates about the short side direction of the reflective display element array. 23. A rear projection type projector according to any one of 23. The rear projection type projector according to claim 24 or 25, wherein M: N is 16: 9.

Images