JP2009015225A - Illumination optical system and projection type display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical system having a compact and simple structure. <P>SOLUTION: The illumination optical system has: a light source section (1) which generates light; an integrator section (4) which makes the in-plane illuminance irregularities of a luminous flux from the light source section (1) uniform; a reflection type display element (10) which displays an image; and an optical system which guides the luminous flux emitted from the integrator (4) to the reflection type display element, to illuminate it. The optical system has: a first lens system (5) whose optical axis is nearly horizontally arranged and which focuses the luminous flux emitted from the integrator (4); a first mirror (6) which reflects the luminous flux from the first lens system (5) and bends the luminous flux in a predetermined angle direction; a second lens system (7) which focuses the luminous flux from the first mirror (6); a second mirror (8) which makes the luminous flux from the second lens system (7) incident on the reflection type display element (10) at a predetermined angle; and a third lens system (9) which focuses the luminous flux from the second mirror (8) on the reflection type display element (10). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an illumination optical system and a projection display device using the illumination optical system.

  Currently, projectors using reflective image display elements are commercialized by various companies. Projectors using a reflective image display element include a single-plate projector using one reflective image display element and a two-plate or three-plate projector using two or three image display elements.

  The most compact type of these is the single-plate projector, but one of the most commonly used single-plate projectors is a reflective type created using the MEMS technology developed by Texas Instruments. There is what is called a Digital Light Processing (trademark) system (hereinafter referred to as DLP (trademark) system) projector using Digital Micro Mirror Device (trademark) (hereinafter referred to as DMD (trademark)) which is a display element.

  Here, the operation principle of the DMD will be described. As shown in FIG. 5, the DMD includes micromirrors 101 and 102 having corners of 13.7 μm or 16.2 μm that are rotatably supported by a hinge on the DMD unit 10 in the vertical and horizontal directions, and are arranged in the number of necessary resolutions. The minute micromirrors 101 and 102 are swung at a binary angle of ± 12 ° (or ± 10 °) from the horizontal position. When the micromirror is held at +12 degrees, the incident light beam is reflected by the micromirror 101 and taken into the projection lens 11, and projected onto a screen (not shown) to display white. However, in the case of −12 degrees, since the incident light beam is held at the angle of the micromirror 102, it is reflected outside the projection lens and absorbed by the light absorbing plate 12. At this time, since no light is projected on the screen, the display is black.

  Therefore, by operating the micromirrors 101 and 102 at high speed and changing the number of times the light is incident on the projection lens 11, the brightness in the eyes of the person who sees the screen according to the integrated amount of the light entering the projection lens 11. Is integrated over time, so that pixels appear to shine at a predetermined brightness, and an image with gradation can be formed.

Further, as can be seen from FIG. 5, illumination light needs to be incident on the DMD from an oblique direction.
One illumination optical system of a single-plate DLP projector includes a non-telecentric illumination optical system in which a chief ray of a light beam that illuminates a DMD surface is incident while being converged.

  As shown in FIG. 2, the light is collected at the light source unit 1 in which a lamp composed of an ultra-high pressure water source lamp that emits white light is arranged at one focal part of the elliptical reflector 2 and at the other focal part of the elliptical reflector 2. A rod integrator 4 having an effect of reducing in-plane luminance unevenness on the exit surface by capturing a secondary light source image of the illuminated lamp and repeating internal reflection, and is disposed in the vicinity of the entrance surface of the rod integrator 4, By rotating a disk-shaped glass plate deposited by dividing a dichroic coat that transmits red, blue, and green light at a predetermined angle from the center of the disc with a motor, the white light from the light source is emitted. The color wheel 3 that is time-divided into three primary colors, red, blue, and green, and the exit end face of the rod integrator 4 are imaged on the image display element surface 8, and the principal ray is focused while the DM is focused. Non-telecentric illumination optical systems 5, 7, and 9 for illuminating the unit 10 and for condensing the principal ray of the luminous flux and condensing the luminous flux so that the principal rays substantially coincide with each other at the rear diaphragm surface of the projection lens 9. The DMD unit 10 that forms an image by expressing the gradation by rapidly swinging the angle of the fine micromirror between two values, and the image displayed on the DMD unit 10 is displayed on a screen surface (not shown). And a projection lens 11 that is enlarged to the above type is known.

  Here, the DMD unit 10 displays an image corresponding to red, blue, and green light time-divided by the color wheel 3. Since this image display is performed at high speed, the afterimage phenomenon of the human eye is synthesized in the brain and perceived as one image.

Japanese Patent Application Laid-Open No. 2004-045718 Japanese Patent Application Laid-Open No. 2002-287081

  However, when the DMD is illuminated with a non-telecentric illumination optical system, since it is incident obliquely while focusing, distortion occurs in the illumination area as shown in FIG.

  In order to solve this problem, in Patent Document 1, as shown in FIG. 3, the chief ray of the illumination light incident on the DMD from the illumination optical system enters in parallel, and the afocal system is used to reduce the distortion of the illumination area. It has been solved. However, since the principal ray of the light beam after DMD reflection also appears in parallel, the projection lens becomes large and is not suitable for miniaturization.

  Further, in Patent Document 2, as shown in FIG. 4, the opening shape of the exit surface of the rod integrator is different from the conventional shape 41 having a rectangular size substantially similar to the shape of the display surface of the DMD. By making the shape 42 compressed by approximately cos θ with respect to the rotation direction, the distortion of the illumination area of the DMD surface is corrected. This is because it is possible to correct the distortion of the illumination area by changing only the rod integrator without changing the conventional illumination optical system, which is advantageous for miniaturization, but the rod integrator is joined in a slanted form. Therefore, the manufacturing process of the optical element becomes complicated, which may lead to an increase in cost.

  The present invention solves the problem that the conventional illumination optical system has caused an increase in the size of the optical system and the complexity of the shape of the rod integrator in order to correct the distortion of the illumination area. An object of the present invention is to provide an illumination optical system having a structure. The present invention also provides a projection display device using such an illumination optical system.

  An illumination optical system according to the present invention includes a light source unit that generates light, an integrator unit that uniformizes in-plane illuminance unevenness of a light beam from the light source unit, a reflective display element that displays an image, and an output from the integrator. An optical system that guides and illuminates a light beam on the surface of the reflective display element, the optical system collecting a light beam emitted from the integrator having an optical axis arranged substantially horizontally, and the first lens system. A first mirror that reflects a light beam from one lens system and bends it in a predetermined angular direction; a second lens system that collects the light beam from the first mirror; and a light beam from a second lens system that reflects the light. A second mirror that is incident on the element at a predetermined angle; and a third lens system that condenses the light beam from the second mirror onto the reflective display element. By arranging the first mirror and the second mirror between the first lens system and the second lens system, respectively, and between the second lens system and the third lens system, the optical system is compacted by folding the optical path in the opposite direction. And can be downsized. Further, the first mirror and the second mirror can also perform distortion correction by canceling out the distortion of the illumination light generated on the reflective optical element surface.

  Preferably, the principal ray of the emitted light beam from the third lens is configured to converge toward the reflective display element.

At least one of the lenses of the first to third lens systems may be an aspheric lens. In this way, it is possible to reduce the aberration of the illumination optical system and improve the imaging performance.
The second mirror may have an adjustment mechanism for adjusting the illumination area.
A projection display device according to the present invention includes the illumination optical system according to the present invention and a projection lens that projects illumination light.
Preferably, the optical axis of the projection lens and the optical axis of the light source are configured to be substantially parallel.

  According to the present invention, an illumination optical system having a small and simple structure is provided.

  FIG. 1 is a schematic view showing the main part of the illumination optical system of the present invention. The illumination optical system of the present invention includes a light source unit 1 in which a lamp composed of an ultra-high pressure water source lamp that emits white light is disposed at one focal point of an elliptical reflector 2 having an optical axis disposed substantially horizontally, and an elliptical reflector 2. A rod integrator 4 having an effect of reducing in-plane luminance unevenness on the exit surface by capturing a secondary light source image of a lamp condensed at one focal point and repeating internal reflection, and incidence of the rod integrator 4 By rotating a disk-shaped glass plate, which is disposed in the vicinity of the surface and vapor-deposited by dividing the dichroic coat that transmits red, blue, and green light at a predetermined angle from the center of the disk with a motor, a light source unit The color wheel 3 that time-divides the white light from the light into the three primary colors of light, red, blue, and green, and the light-emitting side end face of the rod integrator 4 with reduced luminance unevenness are displayed on the image display element. And a plurality of lens systems and mirror with the function of imaging the face 10.

  The plurality of lens systems and mirrors are disposed near the focal point of the first lens 5 and the first lens 5 having a function of condensing the light emitted from the rod integrator 4, and the light flux from the first lens 5 is predetermined. Reflects light from the first mirror 6 that reflects in the angular direction (substantially vertically upward in the illustrated example), the second lens 7 that has a function of condensing the reflected light from the first mirror 6, and the light from the second lens 7. A second mirror 8 having a role of making it enter the display element 10 at a desired angle, and a principal ray from which a reflected light beam from the second mirror 8 diverges is condensed toward the reflection type display element 10, and a reflection type display The third lens 9 has a function of matching the principal ray of the reflected light from the element 10 with the entrance pupil plane of the projection lens 11. The illumination optical system of the present invention is a non-telecentric optical system on the reflective display element 10 side, and is configured vertically as shown in FIG.

  The first mirror 6 and the second mirror 8 are disposed between the first lens 5 and the second lens 7 and between the second lens 7 and the third lens 9, respectively, and the optical paths are in opposite directions as shown in FIG. By turning back, the distortion correction by canceling the distortion of the illumination light generated on the surface of the reflective optical element 11 and the optical axis of the light source 1 and the optical axis of the projection lens 11 are arranged substantially in parallel. Can be achieved. As a result, the optical system can be folded in a compact manner, so that the size can be reduced.

  As described above, when DMD is used in the reflective display element 10, a light beam is incident obliquely. However, in the case of a non-telecentric optical system such as the present illumination optical system, the principal ray is condensed. Since the light enters the reflective display element, distortion occurs in the illumination area.

  FIG. 6 shows an illumination optical system when no mirror is arranged as a comparative example, and FIG. 6 shows an illumination optical system when a second mirror 8 is added between the second lens 7 and the third lens 9 as another comparative example. 7, the illumination optical system when the first mirror 6 is further added between the first lens and the second lens is the vertical illumination optical system of the present invention shown in FIG.

  The distortion of the illumination area of the illumination optical system shown in FIGS. 6, 7, and 1 is shown in FIG. According to this, it can be seen that the vertical illumination optical system using the two mirrors of the present invention has the most improved distortion in the illumination area, so that the illumination area can be reduced. It can be seen that the brightness unevenness in the reflective optical element surface can be reduced. Therefore, it can be seen that the use of the vertical illumination optical system having the configuration of the present invention can improve the distortion of the illumination region without increasing the size of the optical system or complicating the shape of the rod integrator.

  In the above example, each lens is composed of one lens. However, in order to reduce the aberration of the illumination optical system and improve the imaging performance, each lens can be composed of a plurality of lenses to form a lens system or be aspherical. It is.

  Here, it is necessary to adjust the illumination region in order to correct the manufacturing variation of the optical system, but this adjustment is preferably performed by the second mirror 8 having a large area. As a result, it is possible to finely adjust the illumination light and increase the production efficiency.

  By arranging the light source in the opposite direction to the projection lens as in the configuration of the optical system of the present invention, there is also an advantage that the phenomenon that the influence of the radiant heat from the light source affects the projection light and causes fluctuation in the image does not occur. is there.

  Further, by arranging the projection type display device vertically, the projection area on the setting surface such as a desk can be reduced, and it has the advantage that it is easy to carry.

  The present invention is applicable to an illumination optical system and a projection display device using the illumination optical system.

It is the schematic which shows the structure of the illumination optical system of this invention. It is the schematic which shows the structure of the conventional non-telecentric illumination optical system. It is the schematic which shows the structure of the conventional afocal illumination optical system. It is the schematic which shows the improvement of the shape of the conventional rod integrator. It is an operation principle diagram of DMD. It is the schematic which shows the structure of the comparative example of the illumination optical system of this invention which has not arrange | positioned the mirror. It is the schematic which shows the structure of the comparative example of the illumination optical system of this invention which has arrange | positioned only the 2nd mirror. It is a figure which shows the distortion of the illumination area in a reflection type display element surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Elliptic reflector 3 Color wheel 4 Rod integrator 5 1st lens 6 1st mirror 7 2nd lens 8 2nd mirror 9 3rd lens 10 Reflective display element 11 Projection lens 12 Light absorption plates 101 and 102 Micromirror

Claims (6)

A light source unit for generating light;
An integrator unit for uniformizing in-plane illuminance unevenness of a light beam from the light source unit;
A reflective display element for displaying an image;
An optical system that guides and illuminates the luminous flux emitted from the integrator to the reflective display element surface, and the optical system includes:
A first lens system for condensing a light beam emitted from the integrator, the optical axis of which is arranged substantially horizontally;
A first mirror that reflects the light beam from the first lens system and bends it in a predetermined angular direction;
A second lens system for condensing the light beam from the first mirror;
A second mirror that causes a light beam from the second lens system to enter the reflective display element at a predetermined angle;
An illumination optical system comprising: a third lens system that condenses the light beam from the second mirror onto a reflective display element.   The illumination optical system according to claim 1, wherein a principal ray of a light beam emitted from the third lens is focused toward the reflective display element.   The illumination optical system according to claim 1 or 2, wherein at least one of the lenses of the first to third lens systems is an aspheric lens.   4. The illumination optical system according to claim 1, wherein the second mirror has an adjustment mechanism that adjusts an illumination region. 5.   A projection display device comprising: the illumination optical system according to claim 1; and a projection lens that projects illumination light.   6. The projection display device according to claim 5, wherein the optical axis of the projection lens and the optical axis of the light source are substantially parallel.

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