JP2005283818A - Image display apparatus and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized image display apparatus capable of obtaining a bright image having a uniform intensity distribution. <P>SOLUTION: The apparatus is provided with at least two solid light sources; a 1st LED 101a and a 2nd LED 101b, a polarized light beam splitter 104 for transmitting p-polarized light and reflecting s-polarized light, a liquid crystal panel 105 for converting the polarized light from the polarized light beam splitter 104 to the p-polarized light or the s-polarized light, a rod integrator 109 for making the intensity distribution of the light emitted from the solid light sources nearly uniform, a color filter 110 for transmitting light having a prescribed wavelength band among the light from the rod integrator 109 and reflecting the light having a wavelength band different from the prescribed wavelength band, a mirror 107 for reflecting the light advancing toward the 1st LED 101a after being reflected by the color filter 110, and a spatial light modulator 111 for modulating the light from the rod integrator 109 in accordance with an image signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display device and a projector, and more particularly to a technology of an image display device used in combination with a solid light source.

  2. Description of the Related Art Conventionally, in a so-called single-plate projector using a single liquid crystal type spatial light modulator, red light (hereinafter referred to as “R light”), green light (hereinafter referred to as “G light”), and blue are applied to each pixel. There is a method of irradiating light (hereinafter referred to as “B light”). The single-plate projector has an advantage that a simple and small configuration can be achieved as compared with a so-called three-plate projector provided with a spatial light modulator for each color light. In the case of a so-called single-plate type that displays a full-color image using a single liquid crystal spatial light modulator, for example, an R light pixel, a G light pixel, and a B light pixel are provided, and each color light pixel has R light. , G light and B light may be used. As a technique for irradiating each pixel of a liquid crystal type spatial light modulator with R light, G light, and B light, for example, there is one proposed in Patent Document 1.

Japanese Patent No. 2622185

  A configuration proposed in Patent Document 1 will be described. White light from the light source is color-separated into R light, G light, and B light by a color filter that selectively transmits and reflects R light, G light, and B light, respectively. One microlens is arranged for three pixels of the R light pixel, the G light pixel, and the B light pixel. Here, an angle is given to the light that has passed through each light color filter. As a result, the R light color-separated by the color filter is incident on the corresponding R light pixel. The G light color-separated by the color filter enters one corresponding pixel for G light. Further, the B light color-separated by the color filter is incident on a corresponding one pixel for B light. In this way, R light, G light, and B light are expressed by three pixels. In such a configuration of Patent Document 1, since the white light is color-separated by the color filters for each light, the illumination optical system becomes large, which is a problem. Further, with the configuration of the prior art, it is difficult and difficult to obtain a bright image with a uniform intensity distribution.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a small image display device capable of obtaining a bright image with a uniform intensity distribution, and a projector including the image display device.

  In order to solve the above-described problems and achieve the object, according to the first aspect of the present invention, at least two solid-state light sources for supplying light and polarized light in the first vibration direction are transmitted or reflected, and the first The polarized light composition for guiding the polarized light in the first vibration direction and the polarized light in the second vibration direction to the illumination direction by reflecting or transmitting the polarized light in the second vibration direction substantially orthogonal to the vibration direction of , A phase modulation element that converts polarized light from the polarized light combining unit into polarized light in the first vibration direction or polarized light in the second vibration direction, and the intensity distribution of light from the solid-state light source is made substantially uniform Rod integrator, a color filter that transmits light in a specific wavelength region out of light from the rod integrator, and reflects light in another wavelength region different from the specific wavelength region, and a phase modulator element side of the rod integrator Formed on the end face of the It is possible to provide an image display device comprising: a reflection portion that reflects light that is reflected by a filter and travels in the direction of a solid light source; and a spatial light modulation device that modulates light from a rod integrator according to an image signal. .

  The present invention comprises at least two solid state light sources. The solid light source is preferably a light source that supplies so-called white light. Here, white light refers to light that includes both light in a wavelength region having a broad spectrum distribution and light having a peak wavelength in each of R light, G light, and B light. For example, one of the two solid light sources is selectively turned on and the other is turned off. Thereby, the electric current supplied to one solid-state light source can be made larger than a predetermined value. For this reason, it is possible to illuminate the spatial light modulation device with brighter light than in the prior art. Further, the polarized light combining unit transmits polarized light in the first vibration direction, for example, p-polarized light. Further, the polarized light combining unit reflects polarized light in the second vibration direction, for example, s-polarized light. For this reason, the polarized light combining unit alternately emits p-polarized light and s-polarized light in the illumination direction. The phase modulation element converts the polarized light from the polarized light combining unit into polarized light in the first vibration direction or polarized light in the second vibration direction. For example, the phase modulation element transmits p-polarized light as it is when p-polarized light is emitted from the polarized light combining unit. In contrast, when the s-polarized light is emitted from the polarized light combining unit, the phase modulation element rotates the phase by 90 ° and converts it into p-polarized light. As the phase modulation element, for example, a liquid crystal panel can be used. Thereby, a specific vibration direction, for example, p-polarized light can be supplied to the illumination direction. Furthermore, the polarized light having the same vibration direction enters the rod integrator. Incident light is repeatedly reflected in the rod integrator, and is emitted with a substantially uniform intensity distribution. Furthermore, a color filter that transmits light in a specific wavelength region and reflects light in another wavelength region different from the specific wavelength region is formed on the illumination direction side of the rod integrator. For example, consider a color filter for R light that transmits R light and reflects G light and B light. Of the light from the rod integrator, the R light incident on the color filter for R light is transmitted as it is. On the other hand, of the light from the rod integrator, G light and B light incident on the R light color filter are reflected. On the end surface of the rod integrator on the light source side, a reflection portion is formed that reflects light reflected by the color filter and traveling toward the solid light source. For this reason, G light and B light traveling in the direction of the solid light source in the rod integrator are reflected again by the reflecting portion. The reflected G light and B light travel through the rod integrator and reach the color filter. Here, it is incident on a color filter different from the color filter incident on the first time, for example, a color filter for G light or a color filter for B light. Thereby, the G light or the B light passes through the color filter and is emitted in the illumination direction. For the light that is not transmitted through the color filter for the second time, the same process is repeated again. Thereby, finally, all the light can be emitted from the rod integrator except the component absorbed by the optical member. As a result, the spatial light modulator can be illuminated with bright light with a uniform intensity distribution. Accordingly, it is possible to obtain a small image display device capable of obtaining a bright image having a uniform intensity distribution.

  According to a preferred aspect of the present invention, the at least two solid light sources include a first solid light source and a second solid light source, and the first solid light source and the second solid light source are alternately intermittent. It is desirable to light up. By alternately intermittently lighting two solid-state light sources, the current value supplied to one solid-state light source can be increased as compared with a single continuous light source. Therefore, a brighter image than the prior art can be obtained.

  According to a preferred aspect of the present invention, the at least two solid-state light sources include a first solid-state light source and a second solid-state light source. The first solid-state light source is continuously turned on, and the first solid-state light source It is desirable to turn off the first solid-state light source and turn on the second solid-state light source when the intensity of the light falls below a predetermined value. For example, the first solid-state light source is driven with a larger current value than in the prior art. Thereby, an image brighter than the prior art can be obtained. When the solid light source is driven with such a large current value, the lighting life is shortened. In this aspect, when the lighting life of the first solid-state light source ends, the second solid-state light source is switched. Then, the second solid-state light source is lit continuously with a current value larger than that of the prior art. Therefore, a bright image can be obtained.

  Moreover, according to the preferable aspect of this invention, it is desirable for a polarized light synthetic | combination part to have an inorganic polarizing plate. Thereby, an inorganic polarizing plate can be simply formed, for example with metals, such as aluminum. In addition, the polarizing plate has a smaller angle dependency of polarization separation than the polarization beam splitter. For this reason, as a result of efficient polarization separation, the light utilization efficiency is improved.

  According to a preferred aspect of the present invention, it is desirable that at least two solid light sources include three or more solid light sources. Thereby, a brighter image can be obtained.

  Moreover, according to a preferred aspect of the present invention, the rod integrator is desirably a hollow shape having a reflection surface formed on the inner surface. Thereby, light having an angle larger than the total reflection angle can be repeatedly reflected on the inner surface and used. Therefore, the light utilization efficiency is further improved.

  According to the second aspect of the present invention, it is possible to provide a projector having the above-described image display device and a projection lens that projects light from the image display device. The projector includes the image display device described above. For this reason, a bright projection image can be obtained with a small projector.

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

  FIG. 1 shows a schematic configuration of a projector 100 according to Embodiment 1 of the present invention. In this embodiment, a light emitting diode (hereinafter referred to as “LED”) is used as a solid light source. The first LED 101a, which is a first solid light source, and the second LED 101b, which is a second solid light source, supply white light. Here, the white light includes both light in a wavelength region in which the spectrum distribution is continuously broad and light in which the spectrum distribution has discrete peak wavelengths for each of R light, G light, and B light. Say. The first LED 101a and the second LED 101b have the same configuration. For this reason, the first LED 101a will be described as an example. The light emitted from the first LED 101a is reflected toward the polarizing beam splitter 104 side by the reflector 102a. Further, the condensing lens 103a having a positive refractive power condenses the light directly incident from the first LED 101a and the light reflected by the reflector 102a at a position of an opening 108 described later. Thereby, the light from the first LED 101a enters the predetermined surface of the polarization beam splitter 104. Similarly to the light from the first LED 101a, the light from the second LED 101b also enters the other surface of the polarization beam splitter 104.

  The polarization beam splitter 104, which is a polarized light combining unit, is configured by fixing two triangular prisms. A polarizing film 104 made of a dielectric multilayer film is formed on the fixing surface. The polarizing film 104 transmits, for example, p-polarized light that is polarized light in the first vibration direction. The polarizing film 104 reflects, for example, s-polarized light that is polarized light in the second vibration direction substantially orthogonal to the first vibration direction. Accordingly, the polarization beam splitter 104 transmits the p-polarized light component of the light from the first LED 101a and emits it in the illumination direction. Further, the polarization beam splitter 104 reflects the s-polarized light component of the light from the second LED 101b and emits it in the illumination direction. The polarizing film 104a may be configured to reflect p-polarized light and transmit s-polarized light.

  The p-polarized light and the s-polarized light emitted from the polarization beam splitter 104 enter the liquid crystal panel 105 that is a phase modulation element. The liquid crystal panel 105 has an advantage that it is inexpensive and can be used easily. As will be described later, when the first LED 101a is turned on, the second LED 101b is turned off. Further, when the first LED 101 is turned off, the second LED 101b is turned on. Then, the liquid crystal panel 105 rotates the vibration direction of the incident light by 90 ° according to the input signal. For example, when p-polarized light from the first LED 101a is incident, the liquid crystal panel 105 transmits the p-polarized light as it is without rotating the vibration direction. On the other hand, when the s-polarized light from the second LED 101b is incident, the liquid crystal panel 105 rotates the vibration direction by 90 ° according to the input signal, converts it into p-polarized light, and transmits it. Thus, after passing through the liquid crystal panel 105, p-polarized light having a uniform vibration direction can be obtained.

  The p-polarized light transmitted through the liquid crystal panel 105 enters from one surface of the triangular prism 106 having a function of a solid rod integrator. An opening 108 is formed on the incident surface of the triangular prism 106. Around the opening 108, a mirror 107, which is a reflecting portion, is provided. As described above, the condensing lenses 103a and 103b collect the light near the opening 108. For this reason, the light from the first LED 101a and the second LED 101b efficiently enters the triangular prism 106. The p-polarized light incident on the triangular prism 106 is reflected by the inclined surface and the optical path is bent by 90 °. The p-polarized light whose optical path is bent is incident on the rod integrator 109. The rod integrator 109 has a hollow shape in which a reflection surface is formed on the inner surface. The triangular prism 106 is fixed to one end face of the rod integrator 109. The triangular prism 106 and the rod integrator 109 function as an integral integrator optical element. The incident light is repeatedly reflected in the rod integrator 109, and is emitted with the intensity distribution substantially uniform. In particular, by using the hollow rod integrator 109, light having an angle larger than the total reflection angle can be repeatedly reflected on the inner surface. Therefore, the light utilization efficiency is further improved.

  On the illumination direction side of the rod integrator 109, a color filter 110 that transmits light in a specific wavelength region and reflects light in another wavelength region different from the specific wavelength region is formed. The color filter 110 is composed of a plurality of sets of color filters, with one set of three color filters, an R light color filter, a G light color filter, and a B light color filter. The color filter for R light transmits R light and reflects other color light. The color filter for G light transmits G light and reflects other color light. The color filter for B light transmits B light and reflects other color light. Each color light color filter is formed corresponding to each pixel of the spatial light modulator 111.

  Of the light from the rod integrator 109, the R light incident on the R light color filter is transmitted as it is. On the other hand, among the light from the rod integrator 109, the G light and B light incident on the R light color filter are reflected. As described above, the light source side end faces of the rod integrator 109 and the triangular prism 106 are formed with the mirror 107 that is a reflection part that reflects the light reflected by the color filter 110 and traveling toward the first LED 101a.

  The G light and B light traveling in the direction of the solid light source in the rod integrator 109 are reflected again by the mirror 107. The reflected G light and B light travel through the rod integrator 109 and reach the color filter 110. Here, the light is incident on a color filter 110 different from the color filter 110 incident on the first time, such as a color filter for G light or a color filter for B light. As a result, the G light or B light passes through the color filter 110 and is emitted in the illumination direction. The same process is repeated again for the light that is not transmitted through the color filter 110 for the second time. Thereby, finally, all the light can be emitted from the rod integrator 109 except the component absorbed by the optical member. As a result, the spatial light modulator 111 can be illuminated with bright light with a uniform intensity distribution. By recycling the light using the color filter 110 as described above, the light use efficiency can be improved by, for example, about 1.6 times compared to the conventional technique.

  The spatial light modulator 111 modulates incident light according to an image signal and emits it. As the spatial light modulator 111, for example, a transmissive liquid crystal panel can be used. Thereby, a small and bright image with uniform intensity distribution can be obtained. The first LED 101a and the second LED 101b to the spatial light modulator 111 constitute an image display device.

  The projection lens 112 enlarges and projects the image modulated by the spatial light modulator 111 onto the screen 113. As a result, a full-color projection image with a bright and uniform intensity distribution can be obtained.

  The lighting timing of the first LED 101a and the second LED 101b will be described with reference to FIGS. In this embodiment, as described above, one of the two LEDs 101a and 101b is selectively turned on and the other is turned off. Thereby, the electric current supplied to one LED can be made larger than a predetermined value. For this reason, it is possible to illuminate the spatial light modulator 111 with brighter light than in the prior art. For example, in FIG. 2A, the horizontal axis indicates the lighting time T, and the vertical axis indicates the arbitrary light intensity I. In FIG. 2A, first, the first LED 101a is continuously lit for the lighting time T1 indicated by hatching. Then, when the intensity of light from the first LED 101a becomes a predetermined value or less, for example, when the lighting life of the first LED 101a ends, the first LED 101a is turned off and the second LED 101b is turned on. Then, the first LED 101a and the second LED 101b are driven with a larger current value than in the conventional technique. In the present embodiment, for example, driving is performed with a current value approximately 1.3 times the rated current value. Thereby, an image brighter than the prior art can be obtained. When the LED which is a solid light source is driven with such a large current value, the lighting life is shortened. In this aspect, when the lighting life of the first LED 101a ends, the second LED 101b is switched. Then, the second LED 101b is lit continuously. Therefore, a bright image can be obtained with the same lighting lifetime Tend as that of a light source including a conventional single LED.

  Another example of the lighting timing will be described with reference to FIG. After the first LED 101a is lit for the time T3 that is shaded, the second LED 101b is lit for the time T4. Then, the first LED 101a and the second LED 101b are alternately intermittently lit. By alternately intermittently lighting the two solid light sources, the current value supplied to the LED, which is one solid light source, can be increased as compared to when the single solid light sources are continuously lit. Therefore, a bright image can be obtained with the same lighting lifetime Tend as that of a light source including a conventional single LED. Here, the spatial light modulator 111 drives one frame of the image signal with a 60 Hz signal. For this reason, the switching cycle of the liquid crystal panel 105 which is a phase modulation element and the lighting switching cycle of the LED can be set to 60 Hz, for example.

  FIG. 3 shows a schematic configuration of the projector 200 according to the second embodiment of the invention. The present embodiment is different from the first embodiment in that three LEDs are used. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the first LED 201a, the second LED 201b, and the third LED 201c are provided with three LEDs. Each LED supplies white light. Similar to the first embodiment, a reflector 202a and a condenser lens 203a are disposed in the vicinity of the first LED 201a. In the vicinity of the second LED 201b, a reflector 202b and a condenser lens 203b are arranged. The reflectors 202a and 202b and the condensing lenses 203a and 203b have a refractive power that condenses the light from the LEDs 201a and 201b in the vicinity of the opening 108. The light from the first LED 101a and the second LED 101b is synthesized by the polarization beam splitter 204 and emitted. The synthesized light is aligned with the s-polarized light by the liquid crystal panel 205 which is a polarization conversion element. The light aligned with the s-polarized light enters the polarization beam splitter 214.

  The light from the third LED 201c is condensed near the opening 108 by the reflector 202c and the condenser lens 203c. The light from the third LED 201c also enters the polarization beam splitter 214. The polarization beam splitter 214 transmits p-polarized light and reflects and emits s-polarized light. The liquid crystal panel 215 that is a polarization conversion element emits incident light aligned with, for example, p-polarized light.

  White light from the three LEDs 201a, 201b, and 201c aligned with the p-polarized light travels on the same optical path as described in the first embodiment and enters the spatial light modulator 111. In this embodiment, the three LEDs 201a, 201b, and 201c are intermittently turned on alternately. Thereby, the lighting time of one LED can be further shortened as compared with the first embodiment. As a result, the value of the current flowing to one LED can be further increased, so that brighter illumination can be achieved. Further, as described with reference to FIG. 2A, the LEDs 201a, 201b, and 201c may be lit in order until the lighting life is exhausted.

  FIG. 4 shows a schematic configuration of a projector 300 according to Embodiment 3 of the present invention. This embodiment is different from the first embodiment in that a reflective polarizing plate 304 is used instead of the polarizing beam splitter. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  An inorganic polarizing plate 304 can be used as the reflective polarizing plate. As an example of the inorganic polarizing plate 304, a polarizing plate made of metal, for example, aluminum can be given. The reflection-type inorganic polarizing plate is less dependent on the incident angle of the polarization separation characteristic than the polarizing beam splitter. Thereby, the light from LED can be used efficiently. In addition, the inorganic polarizing plate 304 can be easily formed of a metal such as aluminum.

  As described in the above embodiments, according to the present invention, it is possible to obtain a bright and uniform projected intensity projection image with a small projector. Each LED that supplies white light may be either a type including an R light chip, a G light chip, and a B light chip, or a type that emits white light using a phosphor. Furthermore, the phase modulation device is not limited to a liquid crystal panel. For example, it is possible to use a modulation element that magnetically switches polarization at high speed. In addition, the projector is not limited to a projector provided with a transmissive liquid crystal display device as a spatial light modulator, and may be a projector using a reflective liquid crystal display device, for example.

1 is a schematic configuration diagram of a projector according to a first embodiment of the invention. Explanatory drawing of the lighting timing of Example 1. FIG. Explanatory drawing of the other lighting timing of Example 1. FIG. FIG. 6 is a schematic configuration diagram of a projector according to a second embodiment of the invention. FIG. 6 is a schematic configuration diagram of a projector according to a third embodiment of the invention.

Explanation of symbols

100 projector, 101a, 101b LED, 102a, 102b reflector, 103a, 103b condenser lens, 104 polarizing beam splitter, 104a polarizing film, 105 liquid crystal panel, 106 triangular prism, 107 mirror, 108 aperture, 109 rod integrator, 110 color Filter, 111 Spatial light modulator, 112 Projection lens, 113 Screen, 200 Projector, 201a, 201b, 201c LED, 202a, 202b, 202c Reflector, 203a, 203b, 203c Condensing lens, 204, 214 Polarized beam splitter, 204a, 214a Polarizing film, 205, 215 Liquid crystal panel, 300 Projector, 304 Reflective polarizing plate

Claims (7)

At least two solid state light sources supplying light;
By transmitting or reflecting polarized light in the first vibration direction and reflecting or transmitting polarized light in the second vibration direction substantially orthogonal to the first vibration direction, the polarized light in the first vibration direction A polarized light combining unit for guiding the polarized light in the second vibration direction to the illumination direction;
A phase modulation element that converts the polarized light from the polarized light combining unit into polarized light in the first vibration direction or polarized light in the second vibration direction;
A rod integrator for making the intensity distribution of light from the solid-state light source substantially uniform;
A color filter that transmits light in a specific wavelength region of light from the rod integrator and reflects light in another wavelength region different from the specific wavelength region;
A reflecting portion that is formed on an end face of the rod integrator on the phase modulation element side and reflects light that is reflected by the color filter and travels toward the solid-state light source;
An image display device comprising: a spatial light modulator that modulates light from the rod integrator according to an image signal. The at least two solid state light sources comprise a first solid state light source and a second solid state light source;
The image display device according to claim 1, wherein the first solid-state light source and the second solid-state light source are alternately intermittently lit. The at least two solid state light sources comprise a first solid state light source and a second solid state light source;
The first solid light source is continuously turned on, and when the intensity of light from the first solid light source becomes a predetermined value or less, the first solid light source is turned off and the second solid light source is turned on. The image display device according to claim 1.   The image display device according to claim 1, wherein the polarized light combining unit includes an inorganic polarizing plate.   The image display device according to claim 1, wherein at least two of the solid light sources include three or more solid light sources.   The image display apparatus according to claim 1, wherein the rod integrator has a hollow shape in which a reflection surface is formed on an inner surface. The image display device according to any one of claims 1 to 6,
A projector comprising: a projection lens that projects light from the image display device.

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