JP2006330328A - Projection type picture display device with sub display, rear projection television, and digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To add a sub display as another function with simple constitution by effectively using light lost by a polarizing beam splitter (PBS) in a projection type picture display device. <P>SOLUTION: In the projection type picture display device having: an illumination optical system including a light source; the polarizing beam splitter; a reflection type light valve; and a projection optical system, the polarizing beam splitter separates light made incident from the illumination optical system and has an S polarized light emitting surface to emit S polarized light and a P polarized light emitting surface to emit P polarized light. The reflection type light valve is arranged in the vicinity of either the S polarized light emitting surface or the P polarized light emitting surface, and a transmission type light valve constituting the sub display is arranged in the vicinity of the other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection type image display device used for a color image display device such as a projector or a rear projection television.

  The projector market is steadily growing due to the digitalization of corporate activities and the booming home theater.

  At present, projector light valves are mainly transmissive liquid crystal light valves using liquid crystals and DMDs using reflective mirrors. However, recently, projectors of reflective liquid crystal light valves using reflective liquid crystals have been put into practical use, and due to their high performance, there is momentum to break into the two forces of transmissive liquid crystal light valves and DMD, and device development is active It is advanced to.

  The features of this reflective liquid crystal light valve are (1) high-speed response, (2) high contrast, (3) large aperture ratio (narrow pixel spacing), etc. As a data projector, home projector, or rear projection TV, Expectations for high-quality image display taking advantage of these features are increasing.

  A general configuration of a reflective liquid crystal projector is shown in FIG. Illumination light from the light source 1 enters the polarization beam splitter (PBS) 2 and is separated into two linearly polarized light components (S-polarized light and P-polarized light) orthogonal to each other, and the reflected liquid crystal light valve (LCOS) 4 has predetermined polarized light. A direction, for example, S-polarized illumination light is incident. The illumination light modulated by the liquid crystal layer of the reflective liquid crystal light valve 4 is reflected as information light, and this is projected onto the screen 6 by a projection optical system 5 such as a projection lens.

  The reflection type light valve 4 has a configuration as shown in the side sectional view (schematic diagram) of FIG. 6. The pixel electrode 41 is formed in a matrix and a pixel to which an information signal is input from a drive circuit (not shown). An electrode substrate 42 and a transparent substrate 44 on which a transparent electrode 43 is formed are arranged to face each other via a spacer 45, and a liquid crystal 46 is sealed therebetween. Alignment films 47 and 47 for aligning liquid crystals in a predetermined direction are formed on the surfaces of these two substrates.

  In the reflective liquid crystal projector, as in the transmissive liquid crystal projector, the illumination light from the light source is efficiently guided so that the illuminance unevenness on the light valve is small. For example, there is a method using a relay lens or an integrator as shown in [Patent Document 1] (Patent Document 1; refer to “FIG. 1” or “FIG. 7”).

  Further, as a method of effectively using the polarized light (here, P-polarized light) that is transmitted through the polarizing beam splitter as described above, for example, there is a method of installing another reflective light valve as disclosed in [Patent Document 2]. is there. Although the screen illuminance can be increased by using such a method, since the images of the two light valves are superimposed on the screen, the light valve needs to be installed with high accuracy.

  There is [Patent Document 3] as a document previously filed by the present applicant, and as described above, this increases the light utilization efficiency by using a plurality of light valves for one polarization beam splitter. is there. By the way, the light utilization method and application differ from the present invention, which similarly increases the light utilization efficiency.

  As an illumination optical system, for example, as shown in [Patent Document 4], there is a method of illuminating a light valve by dividing white light of a light source into three color light bands. In the present invention, this illumination method is illuminated. There is no problem even if it is incorporated in the optical system as it is.

  Also, as shown in [Patent Document 5], there is known a device that attempts to integrate a digital camera and a projector by sharing a projection optical system.

JP 2001-215448 A JP 2001-174775 A JP 2002-169221 A Japanese Patent No. 3352100 JP 2002-171428 A

In many conventional reflective liquid crystal projectors, as shown in FIG. 5, only S-polarized light is used as light incident on a polarization beam splitter (PBS) from a light source, and P-polarized light is not used as unnecessary light. In other words, 50% of the light is lost here.
As disclosed in [Patent Document 2], there is one in which another reflection type light valve is installed, which is used for the main purpose of image projection. Moreover, it is difficult to say that it is practical except for a large and expensive projector.
Therefore, an object of the present invention is to add a sub-display as another function with a simple configuration by effectively using light lost by a polarization beam splitter (PBS).

The invention of claim 1 is a projection type image display apparatus having an illumination optical system including a light source, a polarization beam splitter, a reflection type light valve, and a projection optical system.
The polarization beam splitter has an “S-polarized light exit surface” that separates light incident from the illumination optical system and emits S-polarized light, and a “P-polarized light exit surface” that emits P-polarized light. ”Or“ P-polarized light exit surface ”, a reflective light valve is disposed in the vicinity of one surface, and a transmissive light valve constituting a sub-display is disposed in the vicinity of the other surface. . Since a transmissive light valve is installed as a sub-display, the light source can be used effectively.

  The light modulated by the reflection type light valve is projected by the projection optical system. The transmissive light valve is illuminated by S-polarized light or P-polarized light, and acts as a direct view display. At this time, a color filter or a neutral density filter may be disposed between the polarizing beam splitter and the transmissive light valve or on the display surface side of the transmissive light valve. As the transmission type light valve, a transmission type light valve using a ferroelectric liquid crystal may be adopted.

  Further, the illumination optical system may be configured to have a light source lamp that emits white light, a reflector, an integrator rod, and a color wheel. Or, an illumination system that supplies light bands of various colors at the same time, and the light bands of the various colors are moved over the surfaces of the reflective light valve and the transmissive light valve, and the portions related to all of the various colors are reflected light. A configuration having an optical system that is simultaneously present in the bulb and the transmissive light bulb may be employed. Furthermore, the illumination optical system may have a light source by a light emitting diode and a relay lens optical system, and light emitting diodes having different emission colors of red, green, and blue are used as light sources, and are displayed by a reflective light valve or a transmissive light valve. It is also conceivable that the image to be processed is a color image by red, green and blue time-division illumination.

  A rear projection television with a sub-display or a digital camera with a sub-display can be configured using any of the above-described projection type image display devices.

  By matching the positional relationship between the reflection type light valve and the transmission type light valve with respect to the illumination system and the polarization beam splitter, a sub-display using light that is normally unnecessary can be added to the projection type image display device. It can also be configured as a rear projection television or a digital camera using this.

  In the projection-type image display apparatus, the S-polarized light and the P-polarized light shown in FIG. 5 are reflected or transmitted by the polarizing plate of the beam splitter, but the “S-polarized light” after being emitted from the beam splitter is “ The behavior with respect to the “S-polarized light exit surface” is the same as the behavior of P-polarized light with respect to the “P-polarized light exit surface”. Therefore, if the transmissive liquid crystal light valve is arranged at the same position as the reflective light valve relative to the “S-polarized light exit surface” with respect to the “P-polarized light exit surface”, the transmissive liquid crystal light valve is uniformly P-polarized light. Can be illuminated.

  However, the illumination light of the projector is very bright to use as a backlight of a transmissive liquid crystal and cannot be directly viewed. For this reason, as shown in “FIG. 5” and “FIG. 7” of [Patent Document 1], before entering the polarization beam splitter, the illumination light is aligned to one of the polarization directions by a polarization conversion element to a transmissive type. It is necessary to reduce the amount of light by making the component guided to the liquid crystal very weak or arranging an ND filter in front of or behind the transmissive liquid crystal.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a main part of a projection-type image display device with a sub-display according to the first embodiment of the present invention.

The projection-type image display apparatus 100 includes a light source 1, a polarization beam splitter 2 to which light from the light source 1 is incident, and a reflection disposed in the vicinity of an “S-polarized light exit surface” that emits S-polarized light of the polarization beam splitter 2. Type light valve 4, a transmissive light valve 7 that is arranged in the vicinity of the “P-polarized light exit surface” that emits the P-polarized light of the polarizing beam splitter 2, and a projection corresponding to the reflective light valve 4. An optical system 5 is included. An image from the projection optical system 5 is projected onto the screen 6. In addition, illustration is abbreviate | omitted about a well-known part.
In FIG. 1, the illumination light from the light source lamp 1a is incident on the polarization beam splitter 2 by the reflector 1b. The illumination light is separated into S-polarized light and P-polarized light by the polarizing plate 3 of the polarization beam splitter 2, the S-polarized light is reflected and guided to the reflective light valve 4, and the P-polarized light is transmitted and guided to the transmissive light valve 7. . At this time, the entire surface of the reflective light valve 4 is illuminated by the S-polarized component of the illumination light. Since the positional relationship of the transmissive light valve 7 with respect to the “P-polarized light exit surface” is equal to the positional relationship of the reflective light valve with respect to the “S-polarized light exit surface”, the transmissive light valve 7 is also entirely covered by the P-polarized light. Illuminated.

  Similar to the conventional projection type image display device, the light guided to the reflection type light valve 4 is appropriately modulated, and the light modulated to the P-polarized light is transmitted through the polarization beam splitter 2 and is screened by the projection optical system 5. 6 is projected.

  On the other hand, the transmissive light valve 3 is illuminated with linearly polarized light. Linearly polarized light is easy to use as a backlight and can display very brightly. However, if it is too bright and difficult to see directly, it is preferable to insert an ND filter before or after the transmissive light valve 3 (both are possible) to reduce the light.

  In addition, although simplified as the light source 1, an example was shown, However, You may make it use the appropriate known illumination optical system which combined the lens suitably.

[Second Embodiment]
A schematic diagram of the second embodiment is shown in FIG. The projection type image display apparatus 100 in FIG. 2 differs from the previous embodiment only in the projection optical system. The same parts as those in the first embodiment are denoted by the same reference numerals. In the present embodiment, the light from the light source 1 is once condensed on the color wheel 8 and converted into color light, and then enters the polarization beam splitter 2 through the relay lens (system) 9, and each light valve 4. , 7. When viewed from the front direction, the color wheel 8 is substantially a color filter 8a as shown in FIG. 3, and when this rotates, the white light emitted from the light source 1 is sequentially converted into RGB color light at a constant period.

  Both the transmissive / reflective light valves 4 and 7 are synchronized with the rotation of the color wheel 8, and color information corresponding to the color light from the illumination optical system is sequentially written to the light valves. As a result, a color image is displayed on the screen 6 or the sub-display (transmission type light valve) 7 in a time-sharing manner, and since this is displayed at a high speed, it is displayed in color by a kind of afterimage phenomenon to human eyes. .

  Such a color display method is called field sequential, but it is generally difficult to perform field sequential with a transmissive light valve (it is easy with a ferroelectric liquid crystal). For this reason, when the sub display may be a single color display, it is preferable to install a color filter in the vicinity of the transmissive light valve to display a single color in order to avoid color mixing. The illumination light modulation / projection is not different from that of the first embodiment and will not be described.

[Third Embodiment]
A schematic diagram of the third embodiment is shown in FIG. The projection optical system according to the third embodiment is a combination of a cross prism 11 using LEDs (RLED: 10a, GLED: 10b, BLED: 10c) of RGB colors as light sources. The illumination light emitted from the RGB LEDs is incident on the polarization beam splitter 2 via the cross prism 11 and the relay lens system 9, and the illumination light guided to the light valves 4 and 7 is sequentially modulated.

  The cross prism 11 is made by joining a plurality of dichroic prisms, and is also called a cross dichroic prism. The colored lights incident on the cross prism 11 are reflected by the surfaces that reflect the corresponding wavelength components, and are emitted from one surface 11d of the cross prism 11 as shown in FIG.

  In the third embodiment, field sequential color display is performed by using RGB LEDs as in the second embodiment. The light bulbs 4 and 7 are sequentially illuminated with three colors by sequentially turning on the RGB LEDs at high speed. Color display can be performed by synchronizing the time-division color illumination of the LED and the color information written in the light valves 4 and 7.

  In each embodiment, the projection type image display device has been described. However, the present invention can also be applied to a rear projection television using such a projection type image display device. Also, by integrating with a digital camera, it can be incorporated into a system having a purpose as shown in [Patent Document 5]. In this case, the sub-display is also used as a display for a digital camera. be able to. It can be applied as a digital camera.

  As described above, according to the present invention, a sub-display using light that is normally unnecessary can be obtained by matching the positional relationship between the reflective light valve and the transmissive light valve with respect to the illumination system and the polarizing beam splitter. It can be applied to a projection type image display device (projector) or the like.

  The present invention does not require installation accuracy in units of μm and can maintain inexpensive and stable performance. Therefore, the present invention can be applied to a small and inexpensive mobile projector, and a transmissive light valve is installed as a sub-display as a light source. Can be used effectively.

It is a schematic diagram which shows the 1st Embodiment of this invention. It is a schematic diagram which shows the 2nd Embodiment of this invention. It is the figure seen from the front direction of the color wheel (color filter). It is a schematic diagram which shows the 3rd Embodiment of this invention. It is a block diagram which shows the general structure of the reflection type liquid crystal projector which concerns on this invention. It is a sectional side view which shows the structure of the reflection type light valve which concerns on this invention.

Explanation of symbols

1. Light source (illumination optical system)
2 ... Polarizing beam splitter 4 ... Reflection type light valve 5 ... Projection optical system 6 ... Screen 7 ... Transmission type light valve (sub-display)
8 ... Color wheel 8a ... Color filter 9 ... Relay lens (system)
10a ... RLED
10b ... GLED
10c ... BLED
11 ... Cross prism 100 ... Projection type image display device

Claims (13)

In a projection type image display apparatus having an illumination optical system including a light source, a polarization beam splitter, a reflective light valve, and a projection optical system,
The polarization beam splitter has an “S-polarized light exit surface” that separates light incident from the illumination optical system and emits S-polarized light, and a “P-polarized light exit surface” that emits P-polarized light. ”Or“ P-polarized light exit surface ”with a sub-display characterized by a reflective light valve located near one surface and a transmissive light valve constituting the sub-display located near the other surface Projection type image display device.   The projection type image display device with a sub-display according to claim 1, wherein the light modulated by the reflection type light valve is projected by the projection optical system.   2. The projection type image display device with sub-display according to claim 1, wherein the transmission type light valve is illuminated with S-polarized light or P-polarized light, and acts as a direct-view type display. .   4. The projection-type image display device with a sub-display according to claim 3, wherein a color filter is disposed between the polarizing beam splitter and the transmissive light valve or on the display surface side of the transmissive light valve. Projection-type image display device with display.   4. The projection type image display device with a sub-display according to claim 3, wherein a neutral density filter is disposed between the polarizing beam splitter and the transmissive light valve or on the display surface side of the transmissive light valve. Projection-type image display device with sub-display.   2. The projection type image display device with sub-display according to claim 1, wherein the transmission type light valve is a transmission type light valve using ferroelectric liquid crystal.   The projection type image display apparatus with a sub-display according to any one of claims 1 to 6, wherein the illumination optical system includes a light source lamp that emits white light, a reflector, an integrator rod, and a color wheel. A projection-type image display device with a sub-display as a feature.   The projection type image display apparatus with a sub-display according to any one of claims 1 to 6, wherein the illumination system supplies light bands of various colors at the same time, and covers the surfaces of the reflective light valve and the transmissive light valve. A projection-type image display device with a sub-display, comprising: an optical system that moves light bands of various colors and causes portions related to all of the various colors to exist simultaneously in the reflective light valve and the transmissive light valve.   7. The projection type image display apparatus with a sub-display according to claim 1, wherein the illumination optical system includes a light source using a light emitting diode and a relay lens optical system. Image display device.   10. The projection type image display apparatus with sub-display according to claim 9, wherein the light source comprises light emitting diodes having different emission colors of red, green and blue.   11. The projection type image display device with a sub-display according to claim 10, wherein the image displayed by the reflection type light valve or the transmission type light valve is a color image by time-division illumination of red, green, and blue. Projection-type image display device with sub-display.   A rear projection television comprising the projection-type image display device with a sub-display according to claim 1. A digital camera comprising the projection-type image display device with a sub-display according to claim 1.

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