JPH10333129A - Projection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a cooling mechanism in a projection type liquid crystal display device to make three organic electric field light emitting elements corresponding to three primary colors functioning as a light source. SOLUTION: Planar organic electric field light emitting elements 105R, 105G and 105B for emitting in red, green and blue respectively are arranged on the back surfaces of liquid crystal display elements 101R, 101G and 101B arranged on the three side surfaces of a dichroic prism 102. The heat generated by the organic electric field light emitting elements is transported to radiation plates 108R, 108G and 108B through heat pipes 107R, 107G and 107B. The three radiation plates are air-cooled by one fan 109.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a light source in a display device for enlarging and projecting an image displayed on a liquid crystal display element with a lens and cooling the light source.

[0002]

2. Description of the Related Art Heretofore, a discharge type light source such as a metal halide lamp has been used as a light source of a projection type liquid crystal display device which is a display device for displaying an image of a liquid crystal display device by enlarging and projecting the image.

In order to reduce the size of the light source and the illumination optical system, a configuration in which a flat light source is disposed on the back of the liquid crystal display device can be considered. As the flat light source, an organic electroluminescent element having an organic thin film as a light emitting layer can be used.

[0004]

However, in a conventional projection type liquid crystal display device using a metal halide lamp, a reflector having a large aperture is required to irradiate divergent light emitted from the lamp onto the liquid crystal display element with good parallelism. Yes,
Further, an optical system is required to decompose the light emitted from the lamp into red, green, and blue light and to guide the liquid crystal display element to display an image of each color, which makes it difficult to miniaturize the device. is there.

When an organic electroluminescent device is used as a light source, the device needs to be cooled in order to suppress heat generation due to a current flowing through the device. Air cooling by a fan is easy, but in the configuration in which organic electroluminescent elements that emit red, green, and blue light respectively are arranged on the back of three liquid crystal display elements that display red, green, and blue images, respectively. When a fan is arranged corresponding to the electroluminescent element, three fans are required, and there is a problem that the noise of the fan increases.

The present invention has been made to solve the above-mentioned problems, and the projection type display device can be reduced in size by using an organic electroluminescent device capable of emitting light with high luminance as a flat light source, and red, green and blue can be obtained. It is another object of the present invention to reduce the noise of the display device by cooling with one fan even when three organic electroluminescent elements that emit light of the respective colors are used as a light source.

[0007]

According to a first aspect of the present invention, there is provided a projection type liquid crystal display device comprising: a first liquid crystal display element for displaying a red component image; and a second liquid crystal display element for displaying a green component image. A third liquid crystal display element for displaying an image of a blue component, a first organic electroluminescent element disposed on the back of the first liquid crystal display element and emitting red light, and the second liquid crystal display element A second organic electroluminescent element that emits green light and is disposed on the back of the third organic electroluminescent element that emits blue light and is disposed on the back of the third liquid crystal display element;
A projection type liquid crystal display device comprising: a combining optical system for combining images displayed on the first, second, and third liquid crystal display elements; and a projection lens for projecting the image combined by the combining optical system. A first, a second, and a third heat receiving plate made of a metal plate having good thermal conductivity are arranged in thermal contact with a back surface of the first, second, and third organic electroluminescent elements; First, second and third heat radiating plates are arranged at positions different from the first, second and third heat receiving plates in correspondence with the respective heat receiving plates, and the first heat receiving plate and the second heat receiving plate are arranged at different positions. 1, the second heat receiving plate and the second heat radiating plate, and the third heat receiving plate and the third heat radiating plate between the first, second and third heat radiating plates, respectively. It is characterized by being thermally connected by a third heat pipe.

According to the above configuration, there is an effect that heat generated in the three organic electroluminescent elements can be transported to an arbitrary place and radiated.

According to a second aspect of the present invention, in the projection type liquid crystal display device, among the first, second and third heat pipes, the first and third heat pipes have a linear shape, and the second and third heat pipes have a linear shape. Is characterized in that the heat pipe is bent at a substantially right angle between the heat receiving plate and the heat radiating plate.

According to the above configuration, there is an effect that the heat radiating plates corresponding to the planar organic electroluminescent elements arranged orthogonally can be arranged compactly.

According to a third aspect of the present invention, there is provided a projection type liquid crystal display device according to the first or second aspect, wherein the first, second and third heat radiation plates are common. It is characterized by being cooled by one fan.

According to the above configuration, the heat generated by the three organic electroluminescent elements can be dissipated by one fan, so that the projection type liquid crystal display device can be downsized.

According to a fourth aspect of the present invention, in the projection type liquid crystal display device according to any one of the first to second aspects, the first, second and third heat sinks are common. The heat sink is thermally connected to one heat sink, and the heat sink is cooled.

According to the above configuration, the heat generated by the three organic electroluminescent elements can be dissipated through one heat sink, so that the projection type liquid crystal display can be downsized.

According to a fifth aspect of the present invention, in the projection type liquid crystal display device according to the fourth aspect, the heat sink is cooled by an electronic cooling element air-cooled by a fan.

According to the above configuration, since the heat generated by the three organic electroluminescent elements can be forcibly dissipated by the thermoelectric cooler through one heat sink, a small-sized projection excellent in the cooling ability of the light source can be obtained. This has the effect that a liquid crystal display device can be provided.

According to a sixth aspect of the present invention, there is provided the projection type liquid crystal display device according to any one of the first to fifth aspects, wherein the first, second and third organic electroluminescent elements are provided. The light emitting layer of each organic electroluminescent element is sandwiched between optical resonator structures.

According to the above configuration, the emission spectrum of light emitted from the organic electroluminescent device can be narrowed,
In addition, since the directivity of the emitted light can be enhanced, there is an effect that a projection type liquid crystal display device having a wide color reproduction range and a bright color can be configured.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a projection type liquid crystal display device according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings (first embodiment). First
The embodiment will be described with reference to FIGS. FIG. 1 is a top view of a basic configuration of a projection type liquid crystal display device. 2 and 3 are views for explaining a mechanism for transmitting heat generated in the organic electroluminescent device to the heat sink. FIG. 4 is a view of the arrangement of the fan and the heat sink seen from the fan.

First, the configuration of the projection type liquid crystal display device will be described with reference to FIG.

Liquid crystal display element 1 for displaying a red component image
01R, a liquid crystal display element 101 for displaying a green component image
Liquid crystal display element 10 for displaying images of G and blue components
1B are arranged to face three surfaces of the dichroic prism 102. The images displayed on these three liquid crystal display elements are synthesized by a dichroic prism 102 and then enlarged and projected on a screen 104 by a projection lens 103. The screen may be a reflection type or a transmission type.

Hereinafter, in the reference numbers in the drawing, R refers to the element relating to the red display, G refers to the element relating to the green display, and B refers to the element relating to the blue display. Will be attached.

Liquid crystal display element 1 for displaying a red component image
An organic electroluminescent element 105R that emits red emission light 110R is disposed on the back of 01R. Synchrotron radiation 11
0R is a planar organic electroluminescent element 105 as shown in FIG.
Radiated in the normal direction of R.

The structure of the organic electroluminescent element 105R that emits light at a wavelength in the red region is such that a TiO ₂ (titanium oxide) thin film serving as a half mirror layer and SiO ₂ are formed on a transparent glass substrate.
(Silicon oxide) laminated structure of thin film, ITO as anode
(Indium tin oxide) TAD for thin film and hole transport layer
A (diamine derivative) thin film, an Eu (europium) complex thin film as a light emitting layer, an Alq ₃ (tris (8-quinolinonato) aluminum) thin film as an electron transport layer, and a MgAg (magnesium silver) thin film as a cathode were sequentially laminated. It can be structured. The structure of such an organic electroluminescent device is described in Japanese Journal of Applied Physics Vol. 33
(1994) pp. L863-L866. With such a structure, the peak wavelength of the emitted light can be about 620 nm.

An optical resonator is constituted by the half mirror layer and the cathode, and the emission spectrum of the emitted light can be narrowed, and the directivity of the light emitting element surface in the normal direction (front direction) can be improved. Can be strengthened.

As the organic light emitting layer which emits light at a wavelength in the red region, a material obtained by adding a dye emitting red light to Alq ₃ can be used in addition to the Eu complex. Since the Eu complex originally has a narrow emission spectrum, there is no need to provide an optical resonator. However, when a material obtained by adding a dye that emits red light to Alq ₃ is used for the light emitting layer, the emission spectrum is broad, The narrowing of the spectrum of the emitted light due to the optical resonator structure becomes remarkable.

Liquid crystal display element 1 for displaying a green component image
On the back of 01G, an organic electroluminescent element 105G that emits green emitted light 110G is arranged. Synchrotron radiation 11
0G is a planar organic electroluminescent element 105 as shown in FIG.
It is emitted in the direction normal to G.

The structure of the organic electroluminescent device 105G that emits light at a wavelength in the green region includes a laminated structure of a TiO ₂ thin film and a SiO ₂ thin film serving as a half mirror layer, an ITO thin film serving as an anode, and holes on a transparent glass substrate. TPD to be the transport layer
(Triphenyldiamine derivative) A to be a thin film and light emitting layer
lq ₃ thin film, and MgAg thin film to be the cathode can be sequentially laminated. The structure of such an organic electroluminescent device is described in AppliedPhysics Letters Vol. 68 (1994).
pp. 1-3. With such a structure, the peak wavelength of the emitted light can be approximately 540 nm.

An optical resonator is constituted by the half mirror layer and the cathode, which can narrow the emission spectrum of the emitted light, and also increases the directivity of the light emitting element surface in the normal direction (front direction). Can be strengthened.

Liquid crystal display element 1 for displaying a blue component image
An organic electroluminescent element 105B that emits blue emission light 110B is disposed on the back of 01B. Synchrotron radiation 11
0B is emitted in the normal direction of the planar organic electroluminescent element 105B.

The structure of the organic electroluminescent device 105B that emits light at a wavelength in the blue region includes a laminated structure of a TiO ₂ thin film and a SiO ₂ thin film as a half mirror layer, an ITO thin film as an anode, and a hole on a transparent glass substrate. TPD thin film serving as a transport layer, distyrylbiphenyl derivative thin film serving as a light emitting layer, Alq ₃ thin film serving as an electron transport layer, and MgA serving as a cathode
g It can be a structure in which thin films are sequentially laminated. The structure of the light emitting layer excluding the half mirror layer is applied physics Vol. 62
No. 10, pages 1015 to 1018 (1993). With such a structure, the peak wavelength of the emitted light is 48
It can be about 0 nm.

An optical resonator is constituted by the half mirror layer and the cathode, and the emission spectrum of the emitted light can be narrowed, and the directivity of the light emitting element surface in the normal direction (front direction) can be improved. Can be strengthened.

As described above, as a light source for illuminating a transmission type liquid crystal display device, the emission spectrum can be narrowed,
In addition, by using an organic electroluminescent element having an optical resonator structure that can enhance the directivity of emitted light,
The color purity can be increased, and the amount of light incident on the projection lens can be increased by suppressing the divergence of light after passing through the liquid crystal display element. Therefore, a bright projection type liquid crystal display device with a wide color reproduction range can be configured.

The liquid crystal display elements 101R, 1R corresponding to each color
The display areas of 01G and 101B have a diagonal size of 1.3.
Inches (about 33 mm), in which case the size of the light emitting area of the organic electroluminescent elements 105R, 105G, 105B is slightly larger than 1.3 inches diagonally,
It is about 1.4 inches (about 36 mm). Projection lens 1
If the magnification of 03 is about 13 times, an image of 17 inches (about 432 mm) diagonally is displayed on the screen 104.

Next, the cooling mechanism of the organic electroluminescent device will be described with reference to FIGS. 1, 2 and 3. FIG.

Organic electroluminescent elements 105R, 105G, 1
The heat receiving plates 106R, 106G,
106B is disposed in thermal contact with grease having good thermal conductivity.

Heat transferred from the organic electroluminescent device to the heat receiving plate is transferred to the heat radiating plates 108R, 108G, 108B by the heat pipes 107R, 107G, 107B. The heat sink is air-cooled by the fan 109. The heat receiving plate and the heat radiating plate are mounted in thermal contact with the heat pipe.

The heat pipe is a heat transfer element having a capillary structure on the inner wall, and a structure in which a working fluid such as pure water or perfluorocarbon is sealed in a metal pipe having a vacuum inside. When heat is applied to one end (heating part) of the heat pipe, the working fluid evaporates and becomes a steam flow, and the other end (cooling part)
Where it is cooled and condensed. The condensed working fluid returns to the heating section by capillary action. In this manner, the evaporation, movement, and condensation are repeated, and the heat applied to the heating unit is transported to the cooling unit.

The size of the heat receiving plates 106R, 106G and 106B is about 33 mm × 25 mm so that heat from the entire surface of the organic electroluminescent element can be effectively received. The size of the heat sinks 108R, 108G, 108B is
80mm x 2 to increase the surface area to radiate heat
It is about 5 mm. Heat pipes 107R, 107G,
The diameter of 107B is about 4 mm and the length is about 130 mm.

The heat pipes 107R and 107B used to cool the organic electroluminescent element 105R that emits red light and the organic electroluminescent element 105B that emits blue light are linear as shown in FIG. In FIG. 2, only the cooling structure corresponding to the organic electroluminescent element 105R that emits red light is illustrated, but the cooling structure corresponding to the organic electroluminescent element 105B that emits blue light is symmetrical to this structure. So I omitted the figure.

The heat pipe 107G used to cool the organic electroluminescent element 105G emitting green light is shown in FIG.
It is bent at a right angle as shown in the figure. The structure in which one heat pipe is bent at a right angle as described above has heat sinks 108R, 108G, and 1 corresponding to three organic electroluminescent elements disposed on three side surfaces of the dichroic prism 102.
08B is a preferred structure for disposing it near one fan 109. With such a structure, the heat generated by the three organic electroluminescent elements can be dissipated by one fan, and the projection type liquid crystal display device can be compared with a structure in which a fan is provided for each organic electroluminescent element. And the noise generated by the fan can be reduced.

FIG. 4 shows a fan 109 and heat sinks 108R, 1R.
It is the figure which looked at the arrangement | positioning of 08G and 108B from the fan side.
If the air volume of the fan is large, as shown in FIG.
1 may be arranged in a space surrounded by three heat sinks.

(Second Embodiment) A second embodiment of the projection type liquid crystal display device of the present invention will be described. Although the basic configuration is the same as that of the first embodiment, only the shape of the heat sink is the same as that of the first embodiment.
Is different from the embodiment. FIG. 6 is a perspective view showing the shape of a heat sink 601R attached to the heat pipe 107R. Fins 602R constituting the heat sink 601R extend in the length direction of the heat pipe. The shape of the heat sink is common to three heat sinks corresponding to the respective organic electroluminescent elements that emit red, green, and blue light.

FIG. 7 shows the fan 109 and the heat radiating plates 601R and 601R.
The figure which shows the arrangement | positioning of 01G and 601B seen through the fan from the fan side is shown.

In this embodiment, the surface area of the radiator plate is increased in order to efficiently dissipate heat from the radiator plate.

(Third Embodiment) A third embodiment of the projection type liquid crystal display device of the present invention will be described with reference to FIGS. The basic configuration is the same as that of the first embodiment, but the structure of the heat radiating part is different. FIG. 8 is a diagram of the basic configuration of the projection type liquid crystal display device as viewed from above, and FIG. 9 is a diagram of the arrangement of the heat sink, the heat radiating plate and the fan as seen through the fan from the fan side.

Organic electroluminescent elements 105R, 106G, 1
The heat generated in the heat pipes 107R, 107B
G, 107B, heat sinks 108R, 108G, 10
Transported to 8B. Heat sinks 108R, 108G, 108
B is attached to the side surface of a heat sink 801 made of a copper block via grease having good thermal conductivity.
An electronic cooling element 802 utilizing the Peltier effect is attached to the heat sink 801 via grease having good thermal conductivity. The electronic cooling element 802 is air-cooled by a fan 803.

In this embodiment, the heat transferred to the radiator plate is positively removed by the electronic cooling element, and the cooling effect of the organic electroluminescent element is enhanced.

Also in this embodiment, since the heat generated by the three organic electroluminescent elements can be collected in one place and dissipated by one electronic cooling element, each of the three organic electroluminescent elements is provided with an electronic cooling element. As compared with the structure having the structure, the projection type liquid crystal display device can be reduced in size, and since only one fan is required, the noise of the fan can be suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to a display device for projecting an image on a screen by a projection lens, but also to a liquid crystal display element formed by a projection lens with a naked eye. Can be applied to a display device for observing an enlarged virtual image.

The present invention can be applied not only to an organic electroluminescent element but also to an apparatus having a plurality of elements requiring cooling.

[0052]

As described above, according to the projection type liquid crystal display device of the present invention, heat generated by a plurality of organic electroluminescent elements is transported to one place by using a heat pipe, and one cooling device such as a fan is provided. Dissipating the heat by the device eliminates the need to install a cooling device for each organic electroluminescent element, so that a small projection type liquid crystal display device with low noise can be provided.

[Brief description of the drawings]

FIG. 1 is a top view of a basic configuration of a projection type liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a view for explaining a mechanism for transmitting heat generated in an organic electroluminescent element to a heat sink in the first embodiment of the present invention.

FIG. 3 is a view for explaining a mechanism for transmitting heat generated in the organic electroluminescent device to a heat sink in the first embodiment of the present invention.

FIG. 4 is a view of the arrangement of the fan and the heat radiating plate according to the first embodiment of the present invention as viewed from the fan.

FIG. 5 is a view showing another example of the arrangement of the fan and the heat radiator in the first embodiment of the present invention, and is a view of the arrangement of the fan and the heat radiator seen from the fan side.

FIG. 6 is a perspective view showing the shape of a heat sink according to a second embodiment of the present invention.

FIG. 7 is a view of an arrangement of a fan and a heat radiating plate according to a second embodiment of the present invention as seen through the fan from the fan side.

FIG. 8 is a diagram illustrating a basic configuration of a projection type liquid crystal display device according to a third embodiment of the present invention as viewed from above.

FIG. 9 is a view of an arrangement of a heat sink, a heat radiating plate, and a fan according to a third embodiment of the present invention as seen through the fan from the fan side.

[Explanation of symbols]

 101R, 101G, 101B Liquid crystal display element 102 Dichroic prism 103 Projection lens 104 Screen 105R, 105G, 105B Organic electroluminescent element 106R, 106G, 106B Heat receiving plate 107, 107R, 107G, 107B Heat pipe 108R, 108G, 108B Heat sink 109, 501, 803 Fan 110R, 110G, 110B Radiated light 601R, 601G, 601B Heat sink 801 Heat sink 802 Electronic cooling element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuya Shimoda 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Satoru Miyashita 3-5-35 Yamato, Suwa-shi, Nagano Seiko-Epson Inside the corporation

Claims (6)

[Claims] A first liquid crystal display element for displaying an image of a red component, a second liquid crystal display element for displaying an image of a green component, and a third liquid crystal display element for displaying an image of a blue component. A first organic electroluminescent device disposed on the back of the first liquid crystal display device and emitting red light; and a second organic electroluminescent device disposed on the back of the second liquid crystal display device and emitting green light. A light emitting element, a third organic electroluminescent element disposed on the back of the third liquid crystal display element and emitting blue light,
A projection type liquid crystal display device comprising: a combining optical system for combining images displayed on the first, second, and third liquid crystal display elements; and a projection lens for projecting the image combined by the combining optical system. A first, a second, and a third heat receiving plate made of a metal plate having good thermal conductivity are arranged in thermal contact with a back surface of the first, second, and third organic electroluminescent elements; First, second and third heat radiating plates are arranged at positions different from the first, second and third heat receiving plates in correspondence with the respective heat receiving plates, and the first heat receiving plate and the second heat receiving plate are arranged at different positions. 1, the second heat receiving plate and the second heat radiating plate, and the third heat receiving plate and the third heat radiating plate between the first, second and third heat radiating plates, respectively. A projection type liquid crystal display device which is thermally connected by a third heat pipe. 2. The first, second, and third heat pipes of the first, second, and third heat pipes have a linear shape, and the second heat pipes are formed by the heat receiving plate and the heat radiator. 2. A projection type liquid crystal display device according to claim 1, wherein the projection type liquid crystal display device has a shape which is bent at substantially right angles between the plates. 3. The projection type liquid crystal display according to claim 1, wherein the first, second and third heat sinks are air-cooled by one common fan. apparatus. 4. The heat sink according to claim 1, wherein the first, second and third heat sinks are thermally connected to a common heat sink, and the heat sink is cooled. 13. A projection type liquid crystal display device according to item 9. 5. The projection type liquid crystal display device according to claim 4, wherein said heat sink is cooled by an electronic cooling element cooled by a fan. 6. The organic electroluminescent device according to claim 1, wherein the light emitting layer of each of the organic electroluminescent devices is sandwiched between optical resonator structures. 6. The projection type liquid crystal display device according to any one of items 5 to 5.