JPH04120530A - Light source device and projection type image display device utilizing the device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides an evening light source device that obtains a substantially parallel luminous flux from a light source, and a device that projects an image formed on a transmissive display panel onto a screen. Regarding a projection type I image display device for
In particular, it is used in large-screen projection television systems and information systems.

(Prior Art) Conventionally, in the Kengen device used for projection type image display devices, parabolic reflectors, elliptical reflectors, spherical mirrors, etc. have been used to convert the light from the light source into parallel rays. There is.

When using a parabolic reflector, the light source is placed at its focal point. When using an elliptical reflector, the light source is
The reflected light from the elliptical reflector placed at the focal point converges at a second focal point.The converged light is made into parallel light by a condenser lens having a focal point at the second focal point. When using a spherical mirror, the light source is placed at its spherical center and the light reflected by the spherical mirror is converged back onto the light source.The thus converged light, together with the direct light from the light source, is placed in a condenser having its focus at the spherical center. The lens makes the light rays parallel.

The parallel light rays are incident on a transmissive display panel, and their intensity is adjusted by each picture element of the panel to display images and characters. Examples of the display panel include a liquid crystal display panel, an electrochromic display, and a display using ceramics such as PLZT (lead lanthanum zirconate titanate). Among these, liquid crystal display panels are widely used in portable televisions, word processor displays, etc., and because of their high degree of perfection, they are also frequently used in projection type image display devices.

Therefore, below, a case will be described in which a liquid crystal display panel is used as a transmissive display panel.

In a matrix-type liquid crystal display panel, the smallest display units called picture elements are regularly arranged, and independent drive voltages are applied to picture element electrodes that constitute these picture elements.

This voltage adjusts the transmittance of the liquid crystal layer constituting each picture element, and images and characters are displayed on the screen. As methods for applying independent driving voltages to each picture element electrode, there are simple matrix method, M I M (Metal-Insul
There is an active matrix method in which a nonlinear two-terminal element such as (Ator-Metal) or a three-terminal switching element such as a thin film transistor is provided for each pixel electrode.

In order to perform high-definition display using an active matrix liquid crystal display panel, the pitch between each picture element must be reduced. As the pitch between picture elements becomes smaller, the aperture ratio, that is, the ratio of the area of the picture elements that contributes to display to the area of the entire display screen decreases. The reduction in the aperture ratio is due to the fact that even if the pitch between picture elements is reduced, all of the constituent elements of the liquid crystal display panel cannot be made similarly small. In other words, due to limitations such as etching accuracy and mask alignment accuracy in photolithography, it is necessary to reduce the width of metal wiring connected to picture element electrodes, the size of nonlinear elements, thin film transistors, etc. below a certain level. Therefore, if you try to obtain a high-definition screen by reducing the pitch between picture elements, the brightness of the screen will decrease.

(Problem to be Solved by the Invention) In order to prevent a decrease in brightness due to higher definition screens, a microlens array having microlenses corresponding to each picture element is installed on the light source side or both sides of the liquid crystal display panel. will be arranged. A structure including such a microlens is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-262131 and Japanese Patent Application Laid-open No. 61-117.
No. 88. FIG. 5 shows how parallel light rays converge when a microlens is used. The parallel light beams are converged onto the liquid crystal display panel 1 by the microlens 15. However, the light incident at an angle of ±θ with respect to the parallel light beam converges at a different position from the position where the parallel light beam converges, resulting in a spot having a diameter of 2xrxtanθ. In this way, the microlens 15 cannot converge all of the light incident in the form of a spot onto the picture element. Therefore, the light incident on the microlens is required to be highly parallel.

However, there is a limit to the degree of parallelism of parallel light rays that can be obtained using a parabolic reflector or an elliptical reflector.

FIGS. 6(a) and 6(b) show how light from a light source travels when an elliptical reflector and a parabolic reflector are used, respectively. When the elliptical reflector 13 is used as shown in FIG. 6(a), the light #2 emitted from the light source 2 located at the first focus of the ellipse reflector 13 is a complete point light source. If so, they all converge to the second focal point of the elliptical reflector. However, since the actual light emitting portion of the light source 2 has a certain length, and due to the precision of the reflecting mirror 13, the light emitted from the light source 2 does not completely converge on the second focal point.

In addition, as shown in FIG. 6(b), the parabolic reflector 23
Even when using the light source 2, the longer the length of the light emitting portion of the light source 2, the larger the angle α of the deviation from the parallel light beam. In this way, when parallel light beams obtained by the elliptical reflector 13 or the parabolic reflector 23 are used, it becomes difficult to fully utilize the effectiveness of the microlens, as shown in FIG. 5 described above. Also, if the length direction of the light emitting part of the light source is aligned with the optical axis, the shadows of the 74 poles of the light source will cause
The distribution of light in a cross section perpendicular to the traveling direction becomes a ring-shaped parallel ray. When an image is projected onto a screen using such light, uneven illuminance occurs, making it impossible to obtain a uniform image.

In a light source device in which a light source is arranged at the spherical center of a spherical mirror and the focus of a condenser lens is made to coincide with the spherical center, the above-mentioned elliptical reflecting mirror 1 is used.
3 or a light source device using a parabolic reflecting mirror 23, better parallel light rays can be obtained. In this light source device, light directed toward a spherical mirror is reflected by the spherical mirror and then converged on the light source again. The light then passes through the light source and is converted into parallel light by a condenser lens.

However, such a light source device using a spherical mirror has a problem in that almost no light emitted from the light source in a direction perpendicular to the optical axis is used, resulting in a decrease in light utilization.

The present invention is intended to solve these problems, and an object of the present invention is to provide a light source device that has a high utilization rate of light from a light source and can obtain a highly parallel luminous flux. Another object of the present invention is to provide a projection type image display device using the above light source device and having a bright screen.

(Means for Solving the Problems) A light source device of the present invention includes a light source, a main spherical mirror that reflects the light from the light source and converges it toward the light source, and a main spherical mirror that reflects the light from the light source and the main spherical mirror. A light source device including a condenser lens that converts reflected light into parallel light beams arranged on an optical axis, first and second rigid spherical mirrors facing each other in a direction perpendicular to the optical axis with the light source in between, and the main lens. a first plane mirror disposed between the spherical mirror and the first rigid spherical mirror; and a second plane mirror disposed between the main spherical mirror and the second rigid spherical mirror; The light emitted in the direction of the first and second rigid spherical mirrors is reflected toward a predetermined convergence point between the main spherical mirror and the light source on the optical axis, and each light beam is directed toward the convergence point. After the light is converged by the first and second plane mirrors to respective condensing points separated by a predetermined distance from the light source in the direction of the first and second rigid spherical mirrors, the light is directed to the condenser lens. The above objective is achieved.

In the projection type image display device of the present invention, the light source device, the transmission type display panel in which a large number of picture elements are formed, and the projection lens system are arranged in this order on the optical axis. The above objectives are achieved.

Further, a microlens array having microlenses corresponding to each of the picture elements is provided on the side where the light source ζ of the transmissive display panel is located, and the light from the light source and the reflected light from the main spherical mirror are transmitted through the microlenses. The reflected light from the first rigid spherical mirror and the first plane mirror is converged by the microlens onto the picture element adjacent to the picture element, and the second rigid spherical mirror and the first plane mirror converge on the picture element. The configuration may be such that the reflected light from the second plane mirror is converged onto another picture element adjacent to the picture element by the microlens.

(Function) In the light source device of the present invention, the first
And the light emitted from the light source toward the rigid spherical mirror of plan 2 is
The light is reflected by the secondary mirrors of the first and cabinet 2 so as to converge to a convergence point located a predetermined distance from the light source on the optical axis between the light source and the main spherical mirror. The first and second plane mirrors converge the thus reflected light to a condensing point that is a predetermined distance away from the light source in the direction of il and the second sub-spherical mirror, and then makes it enter the condenser lens.

In the projection type image display device of the present invention, light from the light source SMM described above is focused onto a picture element by a microlens. In this case, one microlens contains light from the light source, reflected light from the main spherical mirror, reflected light from the first sub-spherical mirror and the plane mirror of the cabinet 1, and the second sub-spherical mirror and second mirror. The reflected light from the plane mirror is incident. The light from the light source and the reflected light from the main spherical mirror are converged by this microlens onto the picture element corresponding to this microlens.

The reflected light from the first sub-spherical mirror and the first plane mirror is converged by this microlens onto a picture element adjacent to the picture element corresponding to this microlens. The reflected light from the second secondary spherical mirror and the second plane mirror is brought adjacent to the picture element corresponding to this microlens by this microlens, and the reflected light from the first secondary spherical mirror and the plane mirror of the canopy 1 is converged. It converges on other picture elements different from the picture element. In this way, in the projection type image display device of the present invention, the light from the first and second secondary spherical mirrors can contribute to display, so a bright display screen can be obtained.

(Example) Examples of the present invention will be described below. FIG. 1 shows a schematic diagram of an embodiment of a projection type image display device of the present invention. The projection type image display device of this embodiment includes a light source device 11, a transmission type display panel 1 on which a large number of picture elements 24 are formed, and a projection lens system 17, which are arranged in this order on the optical axis a. It is arranged in The projection lens system 17 consists of a field lens 6 and a projection lens 7. In addition, the projection type image display device of this embodiment has a transmission type display (channel 1) as shown in FIG.
The light source device [11 side] has a microlens array 5 having microlenses 15 corresponding to each of the picture elements 24.

The light source device 11 includes a light source 2, a main spherical mirror 3 that reflects the light from the light source 2 and converges it toward the light source 2, and a condenser lens that converts the light from the light source 2 and the reflected light from the main spherical mirror 3 into parallel rays. 4, which are arranged on the optical axis a. Furthermore, the light source device 11 has an optical axis a with the light source 2 in between.
a first sub-spherical mirror 30 and a second sub-spherical mirror 31 facing each other in the vertical direction; a first plane mirror 32 disposed between the main spherical mirror 3 and the first sub-spherical mirror 30; and a second plane mirror 33 disposed between the secondary spherical mirrors 31 . The image produced by the projection type image display device of this example is as follows:
It is projected onto the screen 8.

In this example, a metal halide lamp with an arc length of 5- was used as light #2. Here, the arc length refers to the distance between electrodes that perform arc discharge. As the light source 2, in addition to a metal halide lamp, a)\logen lamp, xenon lamp, etc. can be used.

Raw spherical mirror 3 and first and second secondary spherical mirrors 30131
is a spherical mirror with a radius of 50 mm and an outer diameter of 80 mm. The diameter of the condenser lens 4 is 80 g, and the focal length is 60 mm. In this embodiment, an active matrix drive type liquid crystal display panel is used as the transmissive display panel 1. The vertical pitch of the picture element is 190 μm, and the horizontal pitch is 1.
It is 61 μm. The opening of the picture element is 88μm long x 10mm wide.
4 μm, and the aperture ratio of the transmissive display panel l is 30%.

The microlens array 5 includes a large number of microlenses 1 corresponding to each picture element of the display noise 1.
5. The focal length of each microlens 15 is 7
It is 20 μm. The microlens array 5 was formed by imparting a refractive index distribution to glass using an ion exchange method.

The focal length of the field lens 6 is 200ma, and the diameter is 1
00mm. The focal length of the projection lens 7 is 200+w
+, diameter is 40m.

In the light source device 11, the spherical center of the main spherical mirror 3 coincides with the light source 2, so the light emitted from the light source 2 and reflected by the main spherical mirror 3 converges on the light source 2 again and is sent to the condenser lens 4 as a light source. It is incident along with the direct light from 2.

In this embodiment, the light emitted toward the first and second sub-spherical mirrors 30 and 31 also enters the condenser lens 4. FIG. 2 shows the path of light emitted toward the first rigid spherical mirror 30 until it enters the condenser lens 4. Furthermore, the second
The light emitted toward the rigid spherical mirror 31 enters the condenser lens 4 along a path symmetrical to the path shown in FIG. 2 with respect to the optical axis a.

The light emitted from the light source 2 in the direction of the first rigid spherical mirror 30 is converged by the first sub-mirror at a predetermined distance from the light source on the optical axis a between the light source 2 and the main spherical mirror 3. It is reflected so that it converges on a point. Since the first plane mirror is located between the convergence point and the first rigid spherical mirror 30, the light reflected so as to converge at the convergence point is reflected by the first plane mirror, and from the light source 2 to the first The light converges at a focal point C that is a predetermined distance ML away from the rigid spherical mirror 30 . Thereafter, this light enters the condenser lens 4 while diverging, and becomes a substantially parallel light beam.

The distance ML between the light rX2 and the condensing point C is the pitch between the picture elements,
A value obtained by multiplying the ratio of the focal length of the microlens 15 and the focal length of the condenser lens 4, that is, L=190 μmX (60 m/720 μm)=15.
It is set at 8m.

The light source device 11 was constructed by setting the value of L to the above-mentioned 15.8 mm. Assuming that the light utilization rate when condensing light using only the condenser lens 4 without using the spherical mirror 3 is 1, when the main spherical mirror 3 is provided as in the conventional case and the light source 2 is placed at the center of the sphere, The light utilization rate was 1.5-1.6. On the other hand, in the light source device of this example, the light utilization rate is 2.5.
It has improved even more. The reason why the light utilization rate is the same as above is that the light emitted from the light source 2 in the direction of the first and second rigid spherical mirrors 30 and 31 is also used.

In the projection type image display device of this embodiment, as shown in FIG. A luminous flux 40t) that has passed through the light point C, and a luminous flux 4 that has been reflected by the rigid spherical mirror 30 on the east 2 and passed through the condensing point C'.
0c enters one microlens 15a. The microlens 15a is provided corresponding to the picture element 24a of the transmissive display panel 1. The light beam 40a is converged by the microlens 15a and then enters the picture element 24a. The light beam 40b incident on the microlens 15a converges on the picture element 24b adjacent to the picture element 24a. Also,
The light beam 40c incident on the microlens 15a is transmitted to the picture element 2.
4a and converges on a picture element 24c which is different from the picture element 24b. By causing the light transmitted through the microlens 15 to enter different picture elements in this manner, the light from the light source 2 can be used effectively. Therefore, the projection type image display device of this embodiment has a bright display screen.

In addition, when a lenticular lens is used as the microlens 15, the long side direction of the lenticular lens,
It is preferable to match the longitudinal direction of the light emitting portion of the light source 2.

As shown in FIG. 4, when using a transmissive display panel having a delta arrangement in which the rows of picture elements 24 are shifted from each other by a pitch of 1/2, for example, a light beam 40a from the main spherical mirror 3 and light #2 is used. The luminous flux 40c from the second rigid spherical mirror 31 converges on picture element A, and the luminous flux 40b from the first rigid spherical mirror 30 converges on any of picture elements B, C, and D.
The positions of the first and second rigid spherical mirrors 30.31 and the first and second plane mirrors 32.33 are set so that the curves converge on any of the picture elements E, F, and G. With this setting, as described above, it is possible to effectively utilize the light from the light source 2 to obtain a bright display screen.

(Effects of the Invention) The light source device of the present invention is provided with two hard spherical mirrors in addition to the main spherical mirror used in the conventional light source device, so that light sources that are not used in the conventional light source device can be used. light is used effectively. Therefore, the light source device of the present invention has a high light utilization rate.

Furthermore, in the projection type image display device of the present invention using the above light source device, the light from the light source and the living spherical mirror and the light from the two hard spherical mirrors are converged onto different picture elements by one microlens. There is.

Therefore, according to the present invention, a projection type image display device having a bright screen can be obtained. Further, by applying the present invention, it is possible to meet the demand for high-definition images without reducing the brightness of the screen.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the projection type image display device of the present invention, and FIG. 2 is a diagram showing how the light emitted toward the first sub-spherical mirror of the display device of FIG. 1 enters the condenser lens. It is a diagram showing a route. Fig. 3 is a diagram showing how light from a light source device enters a microlens and a transmissive display panel, Fig. 4 is a diagram showing another transmissive display panel constituting the present invention, and Fig. 5 is a diagram showing a microlens. FIGS. 6(a) and 6(b) are diagrams showing how light converges when an elliptical reflector and a parabolic reflector are used, respectively. DESCRIPTION OF SYMBOLS 1... Transmissive display panel, 2... Light source, 3... Main spherical mirror, 4... Condenser lens, 5... Microlens array, 6... Field lens, 7... Projection lens , 8... Screen, 11... Light source device,
15... Micro lens, 17... Projection lens system,
24. 24 a. 24b 24c... picture element, 30... first secondary spherical mirror, 31... second secondary spherical mirror, 32... first plane mirror, 33... second plane mirror. that's all

Claims (1)

[Claims] 1. A light source, a main spherical mirror that reflects the light from the light source and converges it toward the light source, and a condenser that converts the light from the light source and the reflected light from the main spherical mirror into parallel rays. A light source device in which a lens is arranged on an optical axis, first and second sub-spherical mirrors facing each other in a direction perpendicular to the optical axis with the light source in between, the main spherical mirror and the first sub-spherical mirror. a first plane mirror arranged between the main spherical mirror and the second sub spherical mirror, and a second plane mirror arranged between the main spherical mirror and the second sub spherical mirror, The light emitted in the direction of the spherical mirror is reflected toward a predetermined convergence point between the main spherical mirror and the light source on the optical axis, and each light heading toward the convergence point A light source device that enters the condenser lens after converging light from the light source to respective condensing points separated by a predetermined distance in the direction of the first and second sub-spherical mirrors by a second plane mirror. 2. A projection type image display device, wherein the light source device according to claim 1, a transmission type display panel on which a large number of picture elements are formed, and a projection lens system are arranged in this order on the optical axis. 3. A microlens array having microlenses corresponding to each of the picture elements is provided on the light source device side of the transmissive display panel, and the light from the light source and the reflected light from the main spherical mirror are reflected by the microlenses. The reflected light from the first sub-spherical mirror and the first plane mirror is converged on the picture element adjacent to the picture element by the microlens, and the second
3. The projection type image display device according to claim 2, wherein reflected light from the secondary spherical mirror and the second plane mirror is converged by the microlens onto another picture element adjacent to the picture element.