JP2010097863A - Reflector system and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of minimizing the angle of incidence with the improvement of focusing efficiency, in an optical system including a projector. <P>SOLUTION: A group of reflectors 30 in the projector 100 uses a passage for the light emitted from a lamp arc 23 and that travels to the front of a lamp bulb 22 and another passage for light that travels rearward of the lamp. More specifically, the light traveling in front of the lamp bulb 22 is reflected in the conventional fashion at a first parabolic reflector 31 and is made to travel, in parallel with an illumination-system light axis Z0. Meanwhile, the light traveling rearward of the lamp bulb 22 is sequentially reflected, at a second parabolic reflector 32, a third parabolic reflector 33, and a fourth parabolic reflector 34, and is made to travel in parallel with the illumination system light axis Z0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reflector system and a projector, for example, a reflector system for supplying parallel light to an illumination system, and a projector including such a reflector system.

  Brightness is one of the important performance indicators of projectors, and how to increase the amount of light projected from the projector is a major issue, and various technologies have been proposed to improve the brightness. Yes.

  FIG. 8A shows the shape of the reflecting surface of a lamp reflector 230 used in a conventionally used LCD projector. As shown in the drawing, the shape of the reflecting surface is a parabolic shape. The arc center 223 of the lamp bulb 222 is arranged at a parabolic focus, and the incident side fly-eye lens 271 is illuminated. However, with this reflector shape, the incident light amount distribution at the incident-side fly-eye lens 271 has a problem that the vicinity of the illumination system optical axis is extremely reduced. FIG. 8B is also a method that is often used in the past, and is configured by the reflecting surface shape of the lamp reflector 231 and the concave lens 272. The shape of the reflecting surface of the lamp reflector 231 is a spheroid shape, and the light emitted from the lamp arc part is reflected in a condensing manner and returned to parallel light by a concave lens. However, the effect of the illumination method is not so different from that shown in FIG. The light in the vicinity of the illumination system optical axis of the incident-side fly-eye lens 271 has a component close to the reference angle of illumination light to the LCD panel (an angle perpendicular to the LCD) as shown in FIG. The panel's contrast and other performance are the best light components. Therefore, if the amount of light at the reference angle is small, the contrast of the LCD panel is deteriorated, so that the contrast as a product is also lowered.

  Further, the illumination size and the incident angle distribution in the incident side fly-eye lens 271 are in a trade-off relationship. That is, when the f value of the lamp reflector 230 is decreased, the illumination size at the incident side fly-eye lens 271 is decreased and the incident angle distribution is expanded. On the other hand, when the f value is increased, the illumination size at the incident side fly-eye lens 271 is increased and the incident angle distribution is narrowed. When the incident angle distribution at the incident side fly-eye lens 271 is good, the PS separation degree at the PBS (polarized beam splitter) arranged on the output side of the output side fly-eye lens increases. FIG. 6 shows a comparative example of the incident angle distribution in an embodiment described later and the conventional incident angle distribution.

  In general, the PS separation characteristics of PBS vary depending on the incident angle on the deposited film, but the efficiency of PS separation / synthesis is best at the angle of incidence perpendicular to the PBS. Therefore, in the conventional method, if the illumination size of the incident-side fly-eye lens is reduced, the incident angle distribution cannot be narrowed (good), so the PS separation degree of the illumination light immediately before the incident-side polarizing plate is poor, and therefore the projector There was a problem that the light utilization efficiency deteriorated.

Therefore, various techniques have been proposed to efficiently extract parallel light. For example, there is a projection display device that achieves bright display with excellent uniformity of the projected image in the screen, high use efficiency of illumination light (see Patent Document 1). In this projection type display device, the third reflecting surface is arranged in a region where a shadow is formed on the non-light-emitting portion of the light source, and the first reflecting surface, so that light is irradiated to the third reflecting surface, A second reflecting surface is arranged. As a result, the light reflected by the surface of the third reflecting surface is applied to the area where the shadow of the conventional light source has been formed. This compensates for the lack of light in this portion, eliminates the shadowed area in the prior art, and makes the entire screen brighter uniformly. The first and third reflecting surfaces are constituted by a paraboloid of revolution, and the second reflecting surface is constituted by a spheroid.
JP 07-199182 A

  By the way, the technique disclosed in Patent Document 1 aims to extract parallel light efficiently, but the design using this technique is very difficult and not always practical. When this technology is applied, there is an adverse effect that the light collection efficiency deteriorates or the incident angle component of the fly-eye lens needs to be increased, and another technology has been demanded.

  In view of the above problems, an object of the present invention is to provide a technique for reducing an incident angle while improving light collection efficiency in an optical system in a projector.

The device according to the invention relates to a reflector system. This reflector system is a reflector system including a plurality of reflectors that reflect light from a lamp bulb, and the light emitted in front of the lamp bulb is parallel to the optical axis of the illumination system. A first reflector that reflects the light, and a second reflector that reflects the light emitted behind the lamp bulb and converts the light into parallel light that travels outward by a predetermined angle with respect to the illumination system optical axis; and A third reflector that reflects light reflected by the second reflector forward and in a direction approaching the illumination system optical axis, and light reflected by the third reflector is parallel to the illumination system optical axis. A fourth reflector that converts the light into light and reflects the light.
The first reflector has a cylindrical shape formed by rotating a part of the shape of a parabola whose focal point is disposed at the arc center of the lamp bulb about the illumination system optical axis, and the second reflector. The reflector is centered on the illumination system optical axis with a part of the shape of the parabola whose focal point is located at the arc center of the lamp bulb being inclined at a predetermined angle with respect to the illumination system optical axis. The third reflector has a part of a parabola shape in which the central axis is parallel to the central axis of the parabola of the second reflector. The fourth reflector has a cylindrical shape formed by rotating about an optical axis, and the fourth reflector is a parabola whose central axis is parallel to and different from the optical axis of the illumination system, and the front end of the parabola is Coincides with the optical axis of the illumination system It has a conical shape formed by rotating a part of the shape around the optical axis of the illumination system, and the parabolic focus of the third reflector coincides with the parabolic focus of the fourth reflector. Also good.
Another apparatus of the present invention relates to a projector and includes the above-described reflector system.

  ADVANTAGE OF THE INVENTION According to this invention, in the optical system in a projector, the technique which makes incident angle small can be provided, improving a condensing efficiency.

  Next, the best mode for carrying out the present invention (hereinafter simply referred to as “embodiment”) will be specifically described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a projector 100 according to the present embodiment, and is a diagram particularly showing an optical system. The projector 100 is an LCD projector using the LCD panel 80 as a light modulation element, and includes a light source unit 20, a condensing system 70, an LCD panel 80, and a light projecting optical system 90.

  The light source unit 20 includes a lamp bulb 22 that emits light by arc discharge such as a high-pressure mercury lamp, and a reflector group (reflector system) 30. The reflector group 30 has a structure characteristic of the present embodiment, and includes first to fourth parabolic reflectors 31 to 34.

  The light emitted from the lamp bulb 22 is reflected by the reflector 30 to be converted into parallel light, enters the light collecting system 70, and the light that has passed through the light collecting system 70 is irradiated onto the LCD panel 80. The light irradiated on the LCD panel 80 is further optically modulated by the LCD panel 80 and projected onto the screen by the light projecting optical system 90.

  In the condensing system 70, an incident side fly-eye lens 71, an emission side fly-eye lens 72, a PBS 73, a first illumination lens 74, a second illumination lens 75, and an incident-side polarizing plate 76 are arranged in this order from the reflector group 30 side. Configured. In the present embodiment, the characteristics of light incident on the incident-side fly-eye lens 71 of the condensing system 70 from the reflector group 30, particularly the parallelism and the incident angle distribution are improved. Since the elements constituting the light condensing system 70 are generally employed in LCD projectors, description thereof is omitted.

  Based on FIG.2 and FIG.3, the reflector group 30 is demonstrated in detail. FIG. 2 is a view showing the cross-sectional shape of the reflector group 30 and the path of the light emitted from the lamp bulb 22 up to the incident side fly-eye lens 71. FIG. 3 is a diagram for explaining an optical path realized by the reflector group 30. Here, for the sake of convenience, only the optical path emitted upward is illustrated. In the following description, a straight line connecting the apex of the parabola and the focal point is referred to as a “center axis” for convenience. In addition, the parabolic shape (cross-sectional shape) which comprises the 1st-4th parabola reflectors 31-34 is called the 1st-4th parabola 31a-34a, and a part of 1st-4th parabola 31a-34a is an illumination system. Cylindrical bodies or conical bodies having reflecting surfaces formed by rotating the optical axis Z0 about the rotation axis are the first to fourth parabolic reflectors 31 to 34. Further, the inner surfaces of the first to third parabolic reflectors 31 to 33 are reflective surfaces, and the outer surface of the fourth parabolic reflector 34 is a reflective surface. The arrangement of the reflector group 30 will be briefly described. The first parabolic reflector 31 is formed in a cylindrical shape so as to cover the front portion of the lamp arc portion 23, and the second parabolic reflector 32 is arranged at the rear portion of the lamp arc portion 23. It is formed in a cylindrical shape so as to cover it. Further, a third parabolic reflector 33 is formed in a cylindrical shape in front of the first parabolic reflector 31, and a fourth parabolic reflector 34 having the illumination system optical axis Z0 as a central axis in front of the third parabolic reflector 33 is conical. Is formed.

  As shown in the figure, the reflector group 30 has different paths for light emitted from the lamp arc portion 23 depending on whether light travels in front of the lamp bulb 22 or light travels behind the lamp bulb 22. That is, the light traveling in front of the lamp bulb 22 is reflected by the first parabolic reflector 31 as in the prior art, and proceeds in parallel with the illumination system optical axis Z0. On the other hand, the light traveling behind the lamp bulb 22 is reflected in the order of the second parabolic reflector 32, the third parabolic reflector 33, and the fourth parabolic reflector 34, so that the light travels in parallel with the illumination system optical axis Z0.

  The maximum reason for dividing into two routes in this way will be described based on the illumination method 300 generally used in the LCD projector shown in FIGS. The condensing system 70 shown here has the same configuration as the condensing system 70 of the present embodiment. The light emitted to the rear side of the lamp bulb 222 has a light beam angle with respect to the incident-side fly-eye lens 71 because the lamp arc portion 223 is actually not a point light source but has a spread, and the distance to the lamp reflector 230 is short. It gets bigger. For this reason, the illumination efficiency in the incident side fly-eye lens 71 and the PS separation / combination efficiency in the PBS 73 are deteriorated.

  In the present embodiment, as described above, with respect to the conditions for setting two routes, the first to fourth parabolas 31a to 34a that configure the first to fourth parabolic reflectors 31 to 34 mainly using FIG. explain. First, the focal points of the first parabola 31a and the second parabola 32a are made to coincide with the lamp arc part 23 (first focal point A1), and the central axis Z2 of the second parabola 32a is set to the condensing system 70 side (illustrated) of the second parabola 32a. The right-side end P3 is inclined outward, that is, away from the illumination system optical axis Z0 by a predetermined angle θ. Thereby, the light reflected by the second parabolic reflector 32 (second parabola 32a) travels behind the first parabolic reflector 31 (first parabola 31a) as parallel light. The predetermined angle θ is set so that the light reflected by the second parabolic reflector 32 does not hit the first parabolic reflector 31. The rear end P1 of the first parabolic reflector 31 (first parabola 31a) coincides with the first focal point A1, which is the center of the lamp arc portion 23, in the positional relationship in the front-rear direction. Furthermore, the front end point P3 of the second parabolic reflector 32 is positioned in front of the first focal point A1 in the front-rear direction.

  Next, the central axis Z3 of the third parabola 33a is also inclined with respect to the illumination system optical axis Z0 (lamp optical axis) by the same angle θ as the inclination of the central axis Z2 of the second parabola 32a. The front and rear ends P4 and P5 of the third parabolic reflector 33 are set so as to receive all the light reflected by the second parabolic reflector 32.

  When a straight reflecting surface is used in place of the third parabola 33a, the light beam range is in the area D1 near the lamp optical axis of the light beam range (middle illumination) in which the light traveling in front of the lamp is reflected by the first parabola reflector 31. Can't fit. For this reason, the illumination efficiency in the reflector group 30 whole will deteriorate.

  In order to improve this, the cross-sectional shape of the third parabolic reflector 33 is parabolically condensed so that the light is advanced to the fourth parabolic reflector 34. Here, the light reflected from the third parabolic reflector 33 travels so as to be condensed at the focal point A34. Note that the shape and position of the third parabolic reflector 33 are set so that light reflected by the third parabolic reflector 33 and traveling to the fourth parabolic reflector 34 does not hit the first parabolic reflector 31. Then, a fourth parabola 34a, which is a cross-sectional shape of the fourth parabolic reflector 34, is formed so that the central axis Z4 passes through the focal point A34 and is parallel to the illumination system optical axis Z0. In addition, although the reflective surface shape of the 1st-3rd parabola 31a-33a of the 1st-3rd parabola reflectors 31-33 is a concave shape, ie, a shape where the reflective surface turned inside toward the outer side of a light beam, it is a 4th parabola reflector. The shape of the 34th parabola 34a of 34 differs from them, and is a convex shape, ie, a shape opened outward as the outer side of the luminous flux. Thereby, the light incident on the fourth parabolic reflector 34 can be reflected in parallel to the illumination system optical axis Z0 that is the lamp optical axis. As a result, the light beam range can be stored in the area D1 near the lamp optical axis of the light beam range (middle illumination) in which the light traveling forward of the lamp bulb 22 is reflected by the first parabolic reflector 31. The rear end portion P6 of the fourth parabolic reflector 34 is substantially the same height (the same distance from the illumination system optical axis Z0) as the rear end portion P1 of the first parabolic reflector 31.

  In the above description, the third parabola reflector 33 to the fourth parabola reflector 34 are focused rather than collimated, but if this method is applied, for example, the second parabola reflector 32 to the third parabola reflector 33 are used. The third parabolic reflector 33 is advanced from the third parabolic reflector 33 with parallel light, and the incident light is incident on the incident-side fly-eye lens 71 with the cross-sectional shape of the fourth parabolic reflector 34 being a flat surface instead of a parabola. A system in which light is parallel light may be used.

  FIG. 5 shows a simulation result according to the present embodiment and a simulation result when the conventional method is applied with respect to the light amount distribution in the incident side fly-eye lens 71. This is a comparison of the light amount distribution when the lamp light distribution is the same and the illumination range at the incident side fly-eye lens 71 is the same as that of the conventional method. As shown in this figure, the present invention shows that the amount of light at a position near the illumination system optical axis Z0 (= grab and 0 mm from the optical axis) is increased compared to the conventional method.

  FIG. 6 shows the incident angle distribution at the incident-side fly-eye lens 71 in comparison with the simulation result when the conventional method is applied. This is a comparison of the incident angle distribution with the conventional method when the lamp light distribution is the same and the illumination range of the incident side fly-eye lens 71 is the same. As shown in this figure, it can be seen that the present invention increases the angle component whose incident angle distribution is close to the illumination system optical axis (0 degree in grab). In order to improve the PS separation degree of the illumination light immediately before the incident side polarizing plate 76, as described above, it is preferable that the incident angle distribution is narrow, and more preferably, the incident angle is distributed in a small range. . Therefore, according to the simulation result, the incident angle can be distributed in a smaller range than before, and the PS separation degree of the illumination light can be improved, that is, the light utilization efficiency of the projector 100 can be improved.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of the respective constituent elements, and such modifications are also within the scope of the present invention. As such a modified example, as shown in FIG. 7, the reflector corresponding to the first parabolic reflector 31 shown in FIGS. As a result, the light emitted forward of the lamp bulb 22 is reflected by the spherical mirror 131, returns to the lamp bulb 22, passes through the lamp bulb 22, and travels backward. In this way, the light emitted from the lamp bulb 22 can be substantially aligned only with the light behind the lamp bulb 22, and the illumination size can be reduced without deteriorating the incident angle distribution in the incident fly-eye lens. . In addition, in the second parabolic reflector 132 of the modified example, the f-value of the parabola can be larger than the second parabola 32a of the second parabolic reflector 32 of FIG. It can be made even better. Moreover, in this modification, the freedom degree at the time of designing which considered the balance of the illumination size and incident angle distribution in an incident side fly-eye lens improves.

It is a figure which shows schematic structure of the projector based on Embodiment. It is the figure which showed the cross-sectional shape of the reflector group of the projector based on embodiment, and the path | route of the light radiate | emitted from the lamp bulb to the incident side fly eye lens. It is a figure for demonstrating optically the path | route of the light radiate | emitted from the lamp bulb based on Embodiment. A description will be given based on an illumination method generally used for an LCD projector according to the embodiment. It is the figure which showed the light quantity distribution in the incident side fly eye lens based on embodiment as a comparative example with the light quantity distribution of a conventional system. It is the figure which showed the incident angle distribution in the incident side fly-eye lens based on embodiment as a comparative example with the incident angle distribution of a conventional system. It is the figure which showed the cross-sectional shape of the reflector group of a projector, and the path | route of the light radiate | emitted from the lamp bulb to the incident side fly eye lens based on the modification of embodiment. It is the figure which showed the reflective surface shape of the lamp reflector used for the LCD projector based on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Projector 22 Lamp bulb 23 Lamp arc part 30 Reflector 31 1st parabola reflector 32 2nd parabola reflector 33 3rd parabola reflector 34 4th parabola reflector 70 Condensing system

Claims (3)

A reflector system comprising a plurality of rotor-shaped reflectors for reflecting light from a lamp bulb,
A first reflector that reflects light emitted in front of the lamp bulb so as to be parallel to an optical axis of an illumination system;
A second reflector that reflects the light emitted to the rear of the lamp bulb and converts the light into parallel light that travels outward by a predetermined angle with respect to the optical axis of the illumination system;
A third reflector that reflects light reflected by the second reflector forward and in a direction approaching the illumination system optical axis;
A fourth reflector that converts light reflected by the third reflector into light parallel to the illumination system optical axis and reflects the light;
A reflector system comprising: The first reflector has a cylindrical shape formed by rotating a part of the shape of a parabola whose focal point is arranged at the arc center of the lamp bulb around the optical axis of the illumination system,
The second reflector has a part of the shape of a parabola whose focal point is arranged at the arc center of the lamp bulb, and the illumination system light in a state where the central axis of the parabola is inclined at a predetermined angle with respect to the illumination system optical axis It has a cylindrical shape formed by rotating around an axis,
The third reflector is a cylindrical shape formed by rotating a part of a parabola shape whose center axis is parallel to the center axis of the parabola of the second reflector around the optical axis of the illumination system. Have
The fourth reflector is a parabola whose central axis is parallel to and different from the illumination system optical axis, and a part of the shape in which the front end of the parabola coincides with the illumination system optical axis is the illumination. It has a conical shape formed by rotating around the system optical axis,
The reflector system according to claim 1, wherein the parabolic focus of the third reflector and the parabolic focus of the fourth reflector are coincident.   A projector comprising the reflector system according to claim 1.

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