JP2000089139A - Light source device and projection type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high output by using plural light sources without increasing a degree of divergence. SOLUTION: Plural light sources 1, 2 are sequentially turned on in time division manner, and light paths of the light from each light source is sequentially joined to a common light path a light path switching device 3 for switching between reflection and transmission. As an example of this light path switching device 3, a rotary mirror, etc., having a reflecting area and a transmitting area on a disk and switching between reflection and transmission can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device such as a liquid crystal projector and a light source device suitably used for the same.

[0002]

2. Description of the Related Art Conventionally, as a projection type image display device, those shown in FIGS. 12 and 13 have been used.

First, the projection type image display device shown in FIG. 12 will be described.

In this projection type image display device, a light source 1
Light emitted directly from 31 or emitted via reflector 132 is a dichroic mirror 133 that reflects red light and transmits green light and blue light, and a dichroic mirror 134 that reflects green light and transmits blue light. The light is decomposed into three colors of red, green and blue by the total reflection mirror 135. The decomposed light of each color is a liquid crystal light valve 136, 1
37, 138, a total reflection mirror 139, a dichroic mirror 1 that reflects blue light and transmits red light.
40, the light is combined again by the dichroic mirror 141 that reflects the green light and transmits the red light and the blue light. The combined light is projected by the projection lens 142.

Next, the projection type image display device shown in FIG. 13 will be described.

[0006] This projection type image display device is basically the same as that shown in FIG. 12 except that the dichroic mirror 141a,
141b, the light of each color decomposed by the total reflection mirrors 142a and 142b is transmitted to the liquid crystal light valves 143 and 144,
After passing through 145, the cross dichroic prism 1
Recombined by 46. The combined light is projected by the projection lens 147.

In the above conventional projection type image display device,
As the light source 131, generally, a metal halide lamp, a xenon lamp, or the like having spectral characteristics in the entire visible light region is used.

Conventionally, these projection-type image display devices have been required to provide brighter and clearer images. For that purpose, various devices have been devised to date, and increasing the output of the light source as a means for obtaining a bright image is also being studied.

However, in general, the greater the output of the light source, the larger the light emitting portion of the light source, so that the parallelism of the light emitted from the light source deteriorates. For this reason, the light is diverged before reaching the projection lens, and the light collection efficiency is rather deteriorated. That is, the brightness (light output) of the projection type image display device is not proportional to the output of the light source.

Therefore, in order to obtain a bright image, a method using a plurality of light sources as a light source device of a projection type image display apparatus is disclosed in, for example, Japanese Patent Publication No.
No. 08080 discloses this.

[0011] In Japanese Patent Publication No. 2533672,
As shown in FIG. 14, light emitted from a plurality of light sources 111 is combined by a dichroic mirror 112.

On the other hand, in JP-A-6-208080, as shown in FIG. 15, a first light source 121 and n other light sources whose emission optical axis is orthogonal to the emission optical axis of the first light source 121 are shown in FIG. Using the light source 122, n total reflection mirrors 123 are arranged at positions on the emission optical axis of the other light source 122 and separated from the other light source 122 by a distance corresponding to the distance from the first light source 121. Then, Δn half mirrors 124 are arranged at the intersections between the emission optical axis of the first light source 121 or the reflection optical axis of each total reflection mirror 123 and the emission optical axis of each of the other light sources 122. Then, each light source 12 is controlled by the half mirror 124.
A part of the light emitted from the light sources 1 and 122 is reflected in the right angle direction and the other part is transmitted, and the light reflected from the half mirror 124 and the light emitted from the other light source 122 transmitted through the half mirror 124 by the total reflection mirror 123 are reflected. The light emitted from one light source 121 is totally reflected in a direction perpendicular to the direction.

In these prior arts, each light source is always lit, and the manner of combining light paths does not change over time, which is a technique different from the present invention.

[0014]

The light source device of the above-mentioned conventional projection type image display device has the following problems.

In the configuration of Japanese Patent Publication No. 2533672,
As shown in FIG. 14, light emitted from a plurality of light sources 111 is combined by a dichroic mirror 112, and whether light is reflected or transmitted by the dichroic mirror 112 is determined by its wavelength.

For this reason, when a metal halide lamp having a spectral characteristic over the entire visible light range is used, each light source necessarily has a wavelength range that cannot be synthesized. Conversely, when the combined light is considered over the entire visible light range, the respective wavelengths are either the light reflected by the dichroic mirror 112 or the light transmitted therethrough, and therefore cannot be combined basically.

In the configuration disclosed in Japanese Patent Application Laid-Open No. 6-208080, light emitted from a plurality of light sources is basically arranged side by side. Become.

For this reason, when a relatively large light source is condensed on a small area, there is a problem that the parallelism is deteriorated and the light condensing efficiency is reduced.

The present invention has been made to solve such problems of the prior art, and uses a light source device capable of obtaining a high output without increasing the divergence by using a plurality of light sources, and using the light source device. An object of the present invention is to provide a projection-type image display device capable of obtaining a bright display.

[0020]

A light source device according to the present invention comprises a plurality of light sources which are sequentially turned on in a time-division manner, and an optical path switching device which sequentially joins a common optical path by switching an optical path of light from each light source. And the above object is achieved.

The optical path switching device may be a rotating mirror having a reflection area and a transmission area on one disk, and switching between reflection and transmission by rotation.

The switching timing of the optical path switching device and the lighting timing of the plurality of light sources may be synchronously controlled by an optical sensor or an external synchronization signal.

A plurality of light sources may be sequentially turned on so that the lighting time of the light sources partially overlaps with the lighting times of the light sources that are turned on before and after the light source.

[0024] The plurality of light sources may be colored light sources corresponding to at least red, green and blue wavelength ranges.

The colored light source may be constituted by a white light source and a color filter. The projection type image display device of the present invention includes the light source device of the present invention, and an image forming unit that receives light from the light source device and sequentially displays at least red, green, and blue images. Thereby, the above object is achieved.

The switching timing of the optical path switching device and the display timing of the image forming means may be synchronously controlled.

The operation of the present invention will be described below.

According to the present invention, the n light sources are
While one light source is on, do not turn on the other light source,
The first light source to the n-th light source are sequentially turned on.

In general, when the output of a light source (lamp) is limited by a heat load, the instantaneous wattage can be reduced by reducing the duty ratio of the lighting time to one half while keeping the time average wattage of the light source constant. Can be doubled. Here, when n light sources are used, the instantaneous wattage can be increased by n times if the lighting time is 1 / n. Therefore, even if the n light sources are sequentially turned on, it is possible to obtain a total output of n times by synthesizing the light emitted from each light source.

Since each light source is turned on one by one,
By switching between reflection and transmission, the optical paths of the light from the respective light sources can be sequentially merged into a common optical path, and the respective emitted lights can be combined. Therefore, an n-fold output can be obtained with the same light flux (parallelism) as one light source.

An optical path switching device for switching between reflection and transmission can be realized by forming a reflection region (mirror portion) and a transmission region (glass portion) on a disk such as a glass substrate and rotating the disk.

The switching timing of the optical path switching device and the lighting timing of the plurality of light sources may be synchronously controlled by an optical sensor. For example, an optical sensor is provided in a direction perpendicular to the light emitted from the light path switching device. As a result, if the timing of the two is shifted, the light emitted from the light source is reflected when it should be transmitted, and transmitted when it should be reflected, and the light reaches the optical sensor. What is necessary is just to feedback-control the lighting timing of the light source or the operation timing of the optical path switching device so as not to occur.

Alternatively, the switching timing of the optical path switching device and the lighting timing of a plurality of light sources are
By controlling with a common external clock signal or the like, synchronous control can be performed without using an optical sensor.

Further, by making the lighting time of the light source slightly longer than the allotted time of 1 / n and partially overlapping with the lighting time of the light source to be lit before and after that, the light path is switched by switching between reflection and transmission. Even when the switching is performed, the light of either light source is guided to the common optical path during the overlapping lighting time. Therefore, flickering of the display at the time of switching of the optical path switching device can be suppressed.

When sequentially displaying images of each color by the image forming means, the plurality of light sources may be colored light sources corresponding to the wavelength range of each color.

This colored light source can be easily realized by combining a white light source and a color filter without preparing another type of light source for each color.

By combining this light source device with image forming means for sequentially displaying at least the respective red, green and blue images, a projection type image display device capable of obtaining a bright and clear image can be realized.

In this case, the switching timing of the optical path switching device and the display timing of the image forming means can be synchronously controlled by the optical sensor, the external control signal, and the like.

[0039]

Embodiments of the present invention will be specifically described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a view showing a schematic configuration of a light source device according to Embodiment 1 of the present invention.

In this embodiment, the light sources 1 and 2 are 400 W
The light emitted from the light emitting units 11 and 21 is disposed directly or reflected by the ellipsoidal mirrors 12 and 22 so as to be condensed on the glass rod 4.

The light sources 1 and 2 are arranged so that their optical paths are orthogonal to each other as shown in FIG. 1, and a rotating mirror 3 as shown in FIG. 2 is arranged at 45 ° on the optical path.

The rotating mirror 3 is obtained by depositing aluminum on a disk 6 made of glass (hatched portion in FIG. 2). The aluminum portion is a reflection region 6a, and the glass portion is a transmission region 6b.

The rotating mirror 3 is mounted on a pulse motor 7, and switches between transmission and reflection by rotating the mirror, thereby sequentially joining the optical paths of the two light sources 1 and 2 to a common optical path.

Here, as shown in FIG. 3, when the light sensor 5 is mounted in a direction perpendicular to the merging light path, the light sensors 1 and 2 are turned on at timings when they need not be turned on. Light is incident on 5. Therefore, by feeding back a signal from the optical sensor to a lighting circuit (not shown) of the light source, it is possible to synchronously control the switching timing of transmission and reflection of the rotating mirror 3 and the lighting timing of the light sources 1 and 2.

Alternatively, as shown in FIG. 4, an external clock signal may be generated to synchronously control the switching timing between the transmission and reflection of the rotating mirror 3 and the lighting timing of the light sources 1 and 2. According to this method, synchronous control can be performed without using an optical sensor.

In the present embodiment, the switching timing between the transmission and reflection of the rotating mirror 3 and the lighting timing of the light sources 1 and 2 are synchronized by an external clock signal. At this time,
As shown in FIG. 4, by setting the lighting time of the light sources 1 and 2 to 54% each, both the light sources are always turned on when the transmission and reflection of the rotating mirror 3 are switched.
The flicker caused by the timing difference between the lighting of the light source and the switching of the optical path could be eliminated.

In the first embodiment, from the light emitting side of the glass rod 4, a parallelism equivalent to a lamp of 400 W is about 740 W.
Significant brightness could be obtained.

In the first embodiment, two light sources are used, but three or more light sources can be used. For example, when three light sources are used, as shown in FIG.
By arranging the light sources 1, 2, 30 comprising the parabolic mirrors 1, 21, 31 and the parabolic mirrors 12, 22, 32 and the rotating mirror 3, the optical paths of the light from the respective light sources can be merged into a common optical path. .

(Embodiment 2) FIG. 6 is a view showing a schematic configuration of a projection type image display apparatus of Embodiment 2 of the present invention.

In this embodiment, the light sources 8, 9, and 10 are 4
The light emitting units 81, 91, 1
01 or the ellipsoidal mirrors 82, 92, 1
It is arranged so as to be reflected at 02 and condensed on the glass rod 11.

The light sources 8, 9, and 10, as shown in FIG.
The light paths of the light sources 9 and 10 are arranged so as to be orthogonal to the light source 8, and the rotating mirrors 12 and 13 as shown in FIG. 7 are arranged at 45 ° on the optical path.

The rotating mirrors 12 and 13 are formed by evaporating aluminum (hatched portions in FIG. 7) on a disk 17 made of glass.
7a, the glass part is the transmission area 17b.

The rotating mirrors 12 and 13 are attached to a pulse motor 18, and switch between transmission and reflection by rotating them so that the optical paths of the two light sources 8, 9 and 10 are sequentially merged into a common optical path.

Further, on the emission side of each of the light sources 8, 9, and 10, interference filters 14, 15, and 1 made of a dielectric multilayer film are provided.
6 are arranged, and the interference filters 14, 15, 16 are each designed to transmit only light in each of the red, green, and blue wavelength ranges.

On the opposite side of the glass rod 11 from the light source, a projection lens 19 and a liquid crystal display panel 20 for sequentially displaying red, green and blue images are arranged.

Here, as shown in FIG. 8, when the optical sensors 23 and 24 are mounted in a direction perpendicular to the merging optical path, the light sources 8, 9 and
When 10 is lit, light enters the optical sensors 23 and 24. Therefore, by feeding back a signal from the optical sensor to a lighting circuit (not shown) of the light source, the switching timing between the transmission and reflection of the rotating mirrors 12 and 13, the lighting timing of the light sources 8, 9 and 10, and the liquid crystal display panel 20 And the display timing of each color can be controlled synchronously.

Alternatively, as shown in FIG. 9, an external clock signal is generated to switch the transmission and reflection of the rotating mirrors 12 and 13, the lighting timing of the light sources 8, 9 and 10, and each color of the liquid crystal display panel 14. May be controlled synchronously with the display timing. According to this method, synchronous control can be performed without using an optical sensor.

In this embodiment, the switching timing between the transmission and reflection of the rotating mirrors 12, 13 and the lighting timing of the light sources 8, 9, 10 and the display timing of the liquid crystal display panel 20 are synchronized by the external clock signal. At this time,
As shown in FIG. 9, the lighting time of the light sources 8, 9, 10 is set to 40.
By setting the percentage, the two light sources are always turned on when the transmission and reflection of the rotating mirrors 12 and 13 are switched, so that the flicker caused by the timing difference between the lighting of the light sources and the switching of the optical path is eliminated. Was completed.

In the second embodiment, about 1 kW from the light emitting side of the glass rod 11 with a parallelism equivalent to a 400 W lamp.
Significant brightness could be obtained.

In the first and second embodiments, the light was focused on the glass rod by using an ellipsoidal mirror. However, the light was not focused by using the parabolic mirrors 12a and 22a as shown in FIG. After the composition, the light may be transmitted through the fly-eye lens optical system 50. This is the same even when three light sources are used.

As the light source, any light source capable of pulse emission can be used. For example, a high-pressure mercury lamp,
An HID lamp such as a metal halide lamp can be used.

Furthermore, in the first and second embodiments, the optical path switching device is realized by switching between transmission and reflection of the rotating mirror. However, any other optical path switching device that can switch the optical path can be used. May be used. For example, it is often used in a scanning system, and a galvano mirror that changes a reflection direction by rotating a mirror back and forth, or a mirror is deposited on a surface of a polyhedron, and the reflection direction of light is changed by rotating the polyhedron. Using a polygon mirror or a DMD (digital micromirror device) that integrates a number of mirrors (micromirrors) on one chip and changes the direction of reflection of light from the light source by rotating the yoke that supports them, The optical path switching device 25 may be provided by arranging as shown in FIG.

[0064]

As described above in detail, in the case of the present invention, the plurality of light sources are sequentially turned on and the optical paths are switched by the optical path switching device, so that the optical paths of the plurality of light sources are merged into the common optical path. Can be. Unlike the prior art using a dichroic mirror, there is no wavelength range that cannot be synthesized, and the width of the luminous flux does not increase and the parallelism does not deteriorate. A light source device without the need can be realized.

The optical path switching device can be easily realized by switching between reflection and transmission by rotating a rotating mirror having a reflection area and a transmission area formed on a disk such as a glass substrate.

The switching timing of the optical path switching device and the lighting timing of the plurality of light sources are controlled synchronously with an optical sensor, an external synchronization signal, or the like, so that a timing difference between the two can be prevented.

Further, if the lighting time of the light source partially overlaps with the lighting times of the light sources that are illuminated before and after the light source, it is possible to suppress the flickering of the display at the switching timing of the optical path switching device and to obtain a good display characteristic. Is obtained.

When sequentially displaying images of each color by the image forming means, the plurality of light sources may be colored light sources corresponding to the wavelength ranges of the respective colors. Also in this case, a bright light source device in which the use efficiency of light does not decrease can be obtained.

This colored light source can be easily formed by combining a white light source and a color filter without having to prepare another type of light source for each color.

By combining the light source device of the present invention and image forming means for sequentially displaying at least the respective images of red, green and blue, a projection type image display device capable of obtaining a bright and clear image can be realized. Therefore, the present invention is very effective.

Further, the switching timing of the optical path switching device and the display timing of the image forming means can be synchronously controlled by the optical sensor, the external control signal, and the like, so that a good image without flicker can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a light source device according to a first embodiment.

FIG. 2 is a plan view illustrating a rotating mirror in the light source device according to the first embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of another light source device according to the first embodiment.

FIG. 4 is a lighting timing chart in the light source device according to the first embodiment.

FIG. 5 is a diagram showing a schematic configuration of another light source device of the first embodiment.

FIG. 6 is a diagram illustrating a schematic configuration of a light source device according to a second embodiment.

FIG. 7 is a plan view illustrating a rotating mirror in the light source device according to the second embodiment.

FIG. 8 is a diagram illustrating a schematic configuration of another light source device according to the second embodiment.

FIG. 9 is a lighting timing chart in the light source device according to the second embodiment.

FIG. 10 is a diagram showing a schematic configuration of another light source device of the present invention.

FIG. 11 is a diagram showing a schematic configuration of another light source device of the present invention.

FIG. 12 is a diagram showing a schematic configuration of a conventional projection image display device.

FIG. 13 is a diagram showing a schematic configuration of a conventional projection image display device.

FIG. 14 is a diagram showing a schematic configuration of a conventional projection-type image display device using a plurality of light sources.

FIG. 15 is a diagram showing a schematic configuration of a conventional projection-type image display device using a plurality of light sources.

[Description of Signs] 1, 2, 30, 8, 9, 10 Light source 3, 12, 13 Rotating mirror 4, 11 Glass rod 5, 23, 24 Optical sensor 6, 17 Glass substrate 6a, 17a Reflection area 6b, 17b Transmission Area 7,18 Pulse motor 11,21,31,81,91,101 Light emitting part of light source 12,22,32 Elliptical mirror 12a, 22a Parabolic mirror 14,15,16 Interference filter 19 Projection lens 20 Liquid crystal display panel 25 Optical path switching device 50 Fly-eye lens optical system

Claims (8)

[Claims] 1. A light source device comprising: a plurality of light sources that are sequentially turned on in a time-division manner; and an optical path switching device that sequentially joins a common optical path by switching an optical path of light from each light source. 2. The light source device according to claim 1, wherein the optical path switching device is a rotating mirror having a reflection area and a transmission area on one disk and switching between reflection and transmission by rotation. 3. The light source device according to claim 1, wherein the switching timing of the optical path switching device and the lighting timing of the plurality of light sources are synchronously controlled by an optical sensor or an external synchronization signal. 4. The light source device according to claim 1, wherein the plurality of light sources are sequentially turned on such that a lighting time of the light source partially overlaps a lighting time of a light source that is turned on before and after the light source. . 5. A light source device, wherein the plurality of light sources are colored light sources corresponding to at least red, green and blue wavelength ranges. 6. The light source device according to claim 5, wherein the colored light source includes a white light source and a color filter. 7. The light source device according to claim 1, further comprising: an image forming unit that receives light from the light source device and sequentially displays at least red, green, and blue images. Projection type image display device provided. 8. The projection type image display device according to claim 7, wherein a switching timing of the optical path switching device and a display timing of the image forming unit are controlled synchronously.