JP2006267417A - Projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display device which can utilize emission light from a light source with high efficiency and can be downsized. <P>SOLUTION: The projection display device is provided with the light source 11, a rod type optical integrator 12 which converts light emitted by the light source 11 into substantially parallel light having a uniform light intensity distribution and emits the light, a polarized light conversion optical system 30 which converts light made incident from the rod type optical integrator 12 into polarized light having a fixed polarizing direction and emits the polarized light, a liquid crystal display element 16 which modulates light made incident from the polarized light conversion optical system 30 in accordance with an imaging signal and emits the light as imaging signal light and a projection optical system 18 which projects the imaging signal light to a screen 10. Therein, the light source 11 is composed of a light source element 20 made of photonic crystal, a light incident opening part of the rod type optical integrator 12 is constituted so as to be larger than the light source element and the polarized light conversion optical system 30 is constituted of a reflection optical system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection display device suitable for miniaturization.

Projection display devices are used for the purpose of projecting images displayed on a large screen such as a screen as a color image for video appreciation and presentation.
Conventionally, a white light source such as an ultra-high pressure mercury lamp, a metal halide lamp, or a xenon lamp is used as a light source in a projection display device. In recent years, a proposal to use a light emitting diode (LED) as a light source for the purpose of miniaturization. Has been.

Since the light emitted from the LED does not need to remove infrared and ultraviolet rays, it is not necessary to install an IR-UV cut filter, and the power consumption is not large, the power supply device that drives the light source is small, and the amount of heat generated is small. In some cases, no special cooling device is required.
In a conventional optical system using a lamp light source, a lens array integrator composed of a pair of lens arrays is used as an illumination uniformizing optical system.

  Further, in a projection display device using a liquid crystal display element as a spatial light modulation element, only linearly polarized light in one direction can pass through the liquid crystal display element, but the illumination light from the light source is indefinite polarization, In order to increase the utilization efficiency, it is necessary to align the polarization direction with linearly polarized light in one direction. A polarization conversion optical system is used as an optical system for aligning the polarization direction.

As a polarization conversion optical system, a polarization beam splitter (PBS) prism array that separates incident indefinitely polarized light into two orthogonal linearly polarized light, and one linearly polarized light for converting it into the same direction as the other linearly polarized light, There is a PS combiner configured by arranging a reflection mirror prism and a retardation film. A projection display device has been proposed in which light from the light source LED is converted into linearly polarized light in one direction by a PS combiner, passed through a spatial light modulator, and a color image is enlarged and displayed on a screen or the like by a projection lens. (For example, refer to Patent Document 1).
JP 2001-281760 A

  By the way, in order to increase the use efficiency of the illumination light from the LED light source, a PS combiner in which a PBS prism and a phase difference film are arranged as a polarization conversion element that aligns the polarization directions of two orthogonally polarized light beams in one direction is used. In addition, since a retardation film that rotates the polarization direction of linearly polarized light by 90 ° is used, there is a problem in that the light utilization efficiency is lowered due to wavelength dispersion of the refractive index.

  Accordingly, an object of the present invention is to solve the above-described problems and provide a projection display device that can be miniaturized by using light emitted from a light source with high efficiency.

  As means for achieving the above object, the projection display device of the present invention includes a light source, and an illumination light uniformizing optical system that converts the light emitted from the light source into substantially parallel light having a uniform light intensity distribution and emits the light. A polarization conversion optical system that converts the light incident from the illumination light uniformizing optical system into polarized light having a certain polarization direction and emits the light, and modulates the light incident from the polarization conversion optical system according to a video signal In the projection display device including the spatial light modulator that emits the image signal light and the projection optical system that projects the image signal light onto the screen, the light source is a light incident aperture of the illumination light equalizing optical system. Provided is a projection display device characterized in that it is a photonic crystal having fine holes incident in parallel to the part and has a shape smaller than the light incident opening, and the polarization conversion optical system is a reflection optical system Try It is intended.

  According to the projection display device of the present invention, according to claim 1, the light source is a photonic crystal having a fine hole that is incident in parallel to the light incident opening of the illumination light uniformizing optical system, and the light is incident. Since the shape is smaller than the opening and the polarization conversion optical system is a reflection optical system, there is an effect that it is possible to provide a projection display device that can use light emitted from the light source with high efficiency and can be miniaturized. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings by way of preferred examples.

FIG. 1 is a schematic configuration diagram showing a first embodiment of the projection display apparatus of the present invention.
FIG. 2 is a configuration diagram showing a light emitting element using a photonic crystal.
FIG. 3 is a block diagram showing a polarization conversion optical system in the projection display apparatus of the present invention.
As shown in FIG. 1, the projection display apparatus 1A of the first embodiment includes a light source element 11, a rod-type optical integrator 12, a condenser lens 13, a polarization conversion optical system 30, a condensing optical system 15, The liquid crystal display element 16 and the projection lens 18 are included.

  As the light source element 11, a high-intensity LED is used. However, when a necessary luminance cannot be obtained with individual outputs, one or more high-intensity LEDs are used as a light source having an array configuration. Alternatively, a light source using the photonic crystal light source element 20 as a light emitting element is used instead of the high-intensity LED.

  As shown in FIG. 2, the photonic crystal light source element 20 includes an active layer semiconductor 23 (light emitting layer) and a P-type semiconductor 21 that are sequentially formed on an N-type semiconductor 22. The surface of the P-type semiconductor 21 is provided with, for example, a minute circular hole array 24 so that a two-dimensional periodic refractive index difference can be made, so that light emitted from the active layer semiconductor 23 can be reflected by irregular reflection or the like. It is a light source that can use the conditions of a light cone that radiates completely to the outside without loss, realizes light emission with high efficiency, and can limit the radiation direction of light.

  When the illumination light emitted from the light source element 11 has uneven brightness in a plane perpendicular to the optical axis, the light source element 11 is covered with parallel mirrors on four sides in order to make the illumination light uniform. The rod-type optical integrator 12 is disposed in the vicinity of the entrance opening. Here, the size of the entrance opening of the rod-type optical integrator 12 is set larger than that of the light source element 11 so that all the light emitted from the light source element 11 can be captured. The outgoing light from the outgoing rod type optical integrator 12 is made uniform and shaped into substantially parallel light by passing through the condenser lens 13.

  Next, since the substantially parallel light emitted from the condenser lens 13 is indefinitely polarized light, in order to increase the light use efficiency of the illumination light to the liquid crystal display element 16 disposed at a predetermined position where the light travels, It is necessary to align the linearly polarized light in one direction with the polarization conversion optical system 30. The polarization conversion optical system 30 is a reflection optical system.

As shown in FIG. 3A, a polarization conversion optical system 30 using a reflection optical system that generally has a simple configuration and high polarization conversion efficiency is used.
Since the illumination light (indefinite polarized light 37) incident on the polarization conversion optical system 30 is indefinite polarized light, it first passes through the incident surface 31a of the polarization beam splitter (PBS) 31 and is orthogonal to each other by the polarization separation surface 31b. The linearly polarized light is separated into P-polarized light and S-polarized light. One of the two polarized light beams travels straight and exits from the exit surface 31 c of the PBS 31, and the other polarized light is bent 90 ° and exits from the exit surface 31 d of the PBS 31.

On the exit surface 31c of the PBS 31, a right-angle prism 32 having a reflection surface 32a that forms 45 ° with respect to the exit surface 31c is disposed. In addition, a right-angle prism 34 having a reflection surface 34a that forms 45 ° with respect to 31d is disposed on the exit surface 31d of the PBS 31.
One polarized light incident on the right-angle prism 32 is reflected by the reflecting surface 32a, changes its direction by 90 °, and is emitted from the emitting surface 32b. On the other hand, the other polarized light incident on the right-angle prism 34 is reflected by the reflecting surface 34a and is emitted from the emitting surface 34b.

A right-angle prism 33 having a reflection surface 33a that forms 45 ° with respect to the emission surface 31c is disposed on the emission surface 32b of the right-angle prism 32. In addition, a right-angle prism 35 having a reflection surface 35 a that forms 45 ° with respect to the emission surface 34 b is disposed on the emission surface 34 b of the right-angle prism 34.
One polarized light incident on the right-angle prism 33 through the emission surface 32b is reflected by the reflection surface 33a, changed in direction by 90 °, and emitted as linearly polarized light 38 from the emission surface 33b. At this time, the optical axis of the indefinite polarized light 37 and the optical axis of the linearly polarized light 38 are parallel. The other polarized light incident on the right-angle prism 35 through the emission surface 34b is reflected by the reflection surface 35a, changes its direction by 90 °, and is emitted as linearly polarized light 39 from the emission surface 35b. At this time, the optical axis of the indefinite polarized light 37 and the optical axis of the linearly polarized light 39 are parallel.

  Here, since the reflecting surface 32a and the reflecting surface 33a are parallel, even if one polarized light that has passed through the polarization separation surface 31a of the PBS 31 is reflected by the reflecting surface 32a and the reflecting surface 33a, its polarization direction is changed. Instead, the light is emitted as the linearly polarized light 38 from the light exit surface 33b. On the other hand, since the reflecting surface 34a and the reflecting surface 35a form 45 °, the other polarized light reflected by 90 ° by the polarization separation surface 31a of the PBS 31 is reflected by the reflecting surface 34a and the reflecting surface 35a. In the same manner as the image is rotated by 90 °, the polarization direction is rotated by 90 °, and the linearly polarized light 39 is output from the output surface 35b.

The polarization directions of the linearly polarized light 38 and the linearly polarized light 39 are the same.
That is, the indefinitely polarized light incident on the polarization conversion optical system 30 has an optical axis in the same traveling direction, and is emitted as either P-polarized light or S-polarized light.

FIG. 3B shows a configuration of the polarization conversion optical system 40 using a reflection optical system using a flat plate-shaped element. The polarization conversion optical system 40 replaces the dichroic mirror 41 having the dichroic mirror surface 41a in place of the PBS 31 in the polarization conversion optical system 30, and the plane mirror 42 having the reflection surface 42a in place of the right angle prism 32 with the right angle prism 33. The flat mirror 43 having the reflective surface 43a is replaced with the flat mirror 44 having the reflective surface 44a instead of the right-angle prism 34, and the flat mirror 45 having the reflective surface 45a is used instead of the right-angle prism 35.
The indefinite polarized light 47 incident on the polarization conversion optical system 40 is emitted as linearly polarized light 48 and 49 having the same polarization direction.

In the polarization conversion optical system 30 using the reflection optical system described above, the side in the direction separated into the P-polarized light and the S-polarized light with respect to the incident surface 31a of the PBS 31 is a rectangular output surface that is twice as long as the other side. The cross-sectional shape orthogonal to the optical axis of the emitted light is a similar rectangle.
Here, in order to match the aspect ratio of the display unit of the liquid crystal display element 16, the condensing optical system 15 including the lens 15a and the lens 15b having different magnifications in the orthogonal direction is disposed in the subsequent stage of the polarization conversion optical system 30, Thereby, the illumination light can be condensed in the same shape as the display unit of the liquid crystal display element 16, and the illumination efficiency to the display unit can be increased.

The linearly polarized light aligned in one direction illuminated on the liquid crystal display element 16 is optically modulated into a color image here, passes through the projection lens 18 and is enlarged and displayed on the screen 10.
According to the projection display device of the present invention, a light source that constitutes a photonic crystal or a high-intensity light-emitting diode as a light-emitting element, a rod-type light integrator as an illumination light uniformizing optical system, and a polarization with indefinite polarization aligned in a polarization direction By providing a polarization conversion optical system using a reflection optical system, it is possible to efficiently illuminate the liquid crystal display element with high-brightness illumination light, and project a high-brightness image onto the screen. In addition, since the configuration of the illumination optical system can be simplified by using a photonic crystal that emits parallel light having a uniform distribution as a light source, the projection display device can be easily downsized.

FIG. 4 is a schematic configuration diagram showing a second embodiment of the projection display apparatus of the present invention.
The projection display device 1B according to the second embodiment is the same as the projection display device 1A according to the first embodiment except that the light source element 11 is a white light source element 11a and the RGB color filter 17 is disposed after the transmissive liquid crystal display element 16a. The projection display device 1A according to the first embodiment is configured in the same manner.
The indefinitely polarized white light emitted from the white light source element 11a is converted into linearly polarized light in a fixed direction by the polarization conversion optical system 30, so that high-intensity illumination light can be efficiently illuminated on the liquid crystal display element. A luminance image can be projected onto the screen 10.

FIG. 5 is a schematic configuration diagram showing a third embodiment of the projection display apparatus of the present invention.
The projection display device 1C of the third embodiment is configured in the same manner as the projection display device 1B of the second embodiment, except that the light source element 11 is an RGB color light source element 11b in the projection display device 1B of the second embodiment. Is.
The light emitted from the RGB color light source element 11b having three colors of R, G, and B is color-combined by the rod-type light integrator 12 to become white uniform illumination light, passes through the reflective polarization conversion optical system 30, and R By illuminating the transmissive liquid crystal display element 16a having G, B color filters, light is modulated into a color image. Here, by using a light source composed of three colors of R, G, and B, color control of a complicated image can be easily performed.

FIG. 6 is a schematic configuration diagram showing a fourth embodiment of the projection display apparatus of the present invention.
The projection display apparatus 1D of the fourth embodiment is the same as the projection display apparatus 1C of the third embodiment except that the transmissive liquid crystal display element 16b is used instead of the transmissive liquid crystal display element 16a and the RGB color filter 17 is removed. This is the same as the projection display device 1C of the third embodiment.
The R, G, and B lights emitted from the RGB color light source element 11b including three colors of R, G, and B are uniformized by the rod-type light integrator 12, and pass through the reflective polarization conversion optical system 30. The transmissive liquid crystal display element 16b is illuminated. Here, the transmissive liquid crystal display element 16b can display the image signals divided into R, G, and B in time series, and R, G, and B controlled by the signals divided into R, G, and B. The light sources of the respective colors are emitted as optical signals in synchronization with each other. The image projected from the transmissive liquid crystal display element 11b is irradiated with the R, G, and B colors in order on the screen 10, and is time-integrated and recognized as a color image in human vision.

FIG. 7 is a schematic configuration diagram showing a fifth embodiment of the projection display apparatus of the present invention.
The projection display device 1E according to the fifth embodiment is different from the projection display device 1D according to the fourth embodiment in that a polarizing beam splitter 19 and a reflective liquid crystal display device 16c having a predetermined arrangement are used instead of the transmissive liquid crystal display device 16b. Except that the lens 18 is changed to a predetermined arrangement, the projection display device 1D of the fourth embodiment is configured in the same manner.
A reflective liquid crystal display element 16c is used as the liquid crystal display element. In the case of the reflective liquid crystal display element 16c, the display unit is configured to illuminate the reflective liquid crystal display element 16c by changing the optical axis by 90 ° with the polarization beam splitter 19. The light modulated and reflected by the reflective liquid crystal display element 16c has its polarization direction rotated by 90 °, so that it passes through the polarization beam splitter 19 and is enlarged and displayed on the screen 10 via the projection lens 18. .

FIG. 8 is a schematic block diagram showing a sixth embodiment of the projection display apparatus of the present invention.
The projection display device 1F of the sixth embodiment is configured in the same manner as the projection display device 1A of the first embodiment except that the rod type integrator 12 and the condenser lens 13 are deleted from the projection display device 1A of the first embodiment. Is.
When a photonic crystal with uniform and parallel light flux emitted at high output is used as the light source element, it is possible to omit the shaping optical system that makes the illumination light substantially parallel and the illumination uniformization optical system that makes the light distribution uniform. Thus, the illumination device is constituted only by the light source element 11, the polarization conversion optical system 30 by the reflection optical system, and the condensing optical system 15 for illuminating the liquid crystal display element 16, and the light modulated by the liquid crystal display element 16 is projected lens. 18 is enlarged and displayed on the screen 10.
The liquid crystal display element can be efficiently illuminated with high-intensity illumination light, and a high-intensity image can be projected onto the screen. In addition, since the configuration of the illumination optical system can be simplified by using a photonic crystal that emits parallel light having a uniform distribution as a light source, the projection display device can be easily downsized.

FIG. 9 is a schematic configuration diagram showing a seventh embodiment of the projection display apparatus of the present invention.
In the projection display device 1F of the sixth embodiment described above, the cross-sectional shape perpendicular to the optical axis of the illumination light emitted from the polarization conversion optical system 30 by the reflection optical system is the same shape as the display unit of the liquid crystal display element 16. In this case, the condensing optical system 15 can be omitted.
In the projection display device 1G of the seventh embodiment, the illumination device is configured by only the light source element 11 and the polarization conversion optical system 30 including the reflection optical system. The entrance surface side of the liquid crystal display element 16 and the exit surface side of the polarization conversion optical system can be closely arranged, and the light modulated by the liquid crystal display element 16 is enlarged and displayed on the screen 10 via the projection lens 18.
The liquid crystal display element can be efficiently illuminated with high-intensity illumination light, and a high-intensity image can be projected onto the screen. In addition, since the configuration of the illumination optical system can be simplified by using a photonic crystal that emits parallel light having a uniform distribution as a light source, the projection display device can be easily downsized.

  In the projection display device, the first invention is a light source, an illumination light uniformizing optical system that emits light emitted from the light source after being converted into substantially parallel light having a uniform light intensity distribution, and the illumination light uniformizing optics. A polarization conversion optical system that converts light incident from the system into polarized light having a certain polarization direction and emits it, and modulates light incident from the polarization conversion optical system according to the video signal and emits it as video signal light And a projection optical system that projects the video signal light onto a screen. The projection light source comprises a light source element made of a photonic crystal, and the polarization conversion optical system is a reflective optical system. A projection display device characterized by comprising a system.

  According to a second invention, in the first invention, the illumination light uniformizing optical system is composed of a rod-type optical integrator that repeats multiple reflections in a light guide path whose four surfaces are covered with mirrors. The projection display device is characterized in that a shaping optical system for collimating the emitted light is joined to the light emitting end face of the optical integrator.

  According to a third invention, in the first invention, the polarization conversion optical system using the reflection optical system separates the indefinite polarization that is incident incident light into two orthogonally polarized lights by the polarization separation surface, The polarized light is emitted from the first emission surface in the same direction as the incident light, and the other polarized light is emitted from the second emission surface in the direction orthogonal to the incident light, and the first emission surface of the PBS A first right-angle prism arranged at a right angle on its reflection surface and emitting from the emission surface; and an incident light arranged on the emission surface of the first right-angle prism as its reflection surface. A second right-angle prism that is bent at a right angle and emits from the exit surface; and a third prism that is disposed on the second exit surface of the PBS and is bent at a right angle at the reflection surface and exits from the exit surface. On the exit surface of the right angle prism and the third right angle prism And a fourth right-angle prism that bends the incident light at a right angle on the reflection surface and emits the light from the emission surface, and is reflected by the reflection surface of the first right-angle prism and the reflection of the second right-angle prism. Are arranged in parallel with each other, and the reflecting surface of the third right-angle prism and the reflecting surface of the fourth right-angle prism are arranged so as to be orthogonal to each other. The one polarized light separated by the polarization separation film is reflected by the reflecting surfaces of the first and second right-angle prisms, and is reflected by the second right-angle prism as a linearly polarized light having the same optical axis as the optical axis of the incident light. The fourth polarized light is emitted from the light exit surface, and the other polarized light is reflected by the reflective surfaces of the third and fourth right-angle prisms, and the fourth right-angle prism is linearly polarized light having the same polarization direction and optical axis as the linearly polarized light. Exit from the exit surface A projection display device, characterized in that the sea urchin configuration.

  According to a fourth aspect of the present invention based on the third aspect, each of the exit surfaces of the second and fourth right-angle prisms has the same size as the first side with respect to the incident surface of the PBS, and the second side A condensing optical system having different magnifications in orthogonal directions so as to be a rectangular surface having a size twice as large as that of the display unit of the spatial light modulation element is used as each emission surface and the space. The projection display device is characterized in that it is arranged in the middle of the light modulation element.

  Further, a fifth invention is the color filter according to the first invention, wherein the light source comprises at least one semiconductor light emitting element light source that emits white light, and transmits only light wavelengths of red, green, and blue. Is disposed in the middle of the spatial light modulation element and the projection optical system.

  In a sixth aspect based on the first aspect, the light source is composed of at least one set of semiconductor light emitting elements that emit red light, green light, and blue light, and the spatial light modulation element is red, green. A projection display device comprising a liquid crystal display element capable of displaying an image signal divided into blue in red, green and blue in time series.

According to a seventh aspect of the present invention, there is provided a projection display device that converts light from a light source into image signal light by a spatial light modulator, and projects the image signal light onto a screen by a projection optical system.
The light source is composed of a photonic crystal light-emitting element, and the light emitted from the light source is converted into a constant linearly polarized light by a polarization conversion optical system using a reflection optical system and is incident on the spatial light modulation element. This is a projection display device.

It is a schematic block diagram which shows 1st Example of the projection display apparatus of this invention. It is a block diagram which shows the light emitting element using a photonic crystal. It is a block diagram which shows the polarization conversion optical system in the projection display apparatus of this invention. It is a schematic block diagram which shows 2nd Example of the projection display apparatus of this invention. It is a schematic block diagram which shows 3rd Example of the projection display apparatus of this invention. It is a schematic block diagram which shows 4th Example of the projection display apparatus of this invention. It is a schematic block diagram which shows 5th Example of the projection display apparatus of this invention. It is a schematic block diagram which shows 6th Example of the projection display apparatus of this invention. It is a schematic block diagram which shows 7th Example of the projection display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A, 1B, 1C, 1D, 1E, 1F, 1G ... Projection display apparatus, 10 ... Screen, 11 ... Light source element, 11a ... White light source element, 11b ... RGB color light source element, 12 ... Rod type light integrator, 13 ... Capacitor Lens 15, condensing optical system, 15 a, 15 b lens, 16 liquid crystal display element, 16 a transmissive liquid crystal display element, 16 b transmissive liquid crystal display element, 16 c reflective display element, 17 RGB color filter, 18: projection lens, 19: polarization beam splitter, 20 ... photonic crystal light source element, 21 ... P-type semiconductor, 22 ... N-type semiconductor, 23 ... active layer semiconductor, 24 ... circular hole array, 30 ... polarization conversion optical system, DESCRIPTION OF SYMBOLS 31 ... Polarizing beam splitter (PBS), 31a ... Incident surface, 31b ... Polarization separation surface, 31c ... Outgoing surface, 31d ... Outgoing surface, 32 ... Right angle prism, 3 a ... reflecting surface, 32b ... output surface, 33 ... right angle prism, 33a ... reflecting surface, 33b ... output surface, 34 ... right angle prism, 34a ... reflecting surface, 34b ... output surface, 35 ... right angle prism, 35a ... reflecting surface, 35b: exit surface, 37: indefinite polarized light (illumination light), 38, 39 ... linearly polarized light, 40 ... polarization conversion optical system, 41 ... dichroic mirror, 41a ... dichroic mirror surface, 42 ... plane mirror, 42a ... reflective surface, 43 ... plane mirror, 43a ... reflecting surface, 44 ... plane mirror, 44a ... reflecting surface, 45 ... plane mirror, 45a ... reflecting surface, 47 ... indefinite polarization, 48, 49 ... linearly polarized light.

Claims (1)

A light source, an illumination light uniformizing optical system that emits light emitted from the light source after being converted into substantially parallel light having a uniform light intensity distribution, and light incident from the illumination light uniformizing optical system in a certain polarization direction A polarization conversion optical system that converts the light into polarized light that is emitted, a spatial light modulator that modulates light incident from the polarization conversion optical system according to a video signal, and emits the light as video signal light, and the video signal light In a projection display device provided with a projection optical system that projects
The light source is a photonic crystal having fine holes that are incident in parallel to the light incident opening of the illumination light uniformizing optical system, and has a shape smaller than the light incident opening, and the polarization conversion optical system is A projection display device characterized by being a reflection optical system.