JPH0713713B2 - LCD projector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal projector.

[Prior Art] A liquid crystal projector displays an image by using a transmissive liquid crystal display panel and projects a display image of the liquid crystal display panel on a screen surface by a projection lens in an enlarged manner. It has become a structure.

That is, FIG. 6 shows a conventional liquid crystal projector. In FIG. 6, 1 is a transmissive dot matrix liquid crystal display panel, 2 is a light source section provided behind the liquid crystal display panel 1, and 2 is a light source section. Is composed of a light source lamp 3 and a reflector 4 that reflects the illumination light from the light source lamp 3 toward the back surface of the liquid crystal display panel 1. The sixth
In the figure, a liquid crystal projector using a parabolic reflector having a parabolic reflection surface for reflecting the light from the light source lamp 3 as parallel light to the liquid crystal display panel 1 side is shown as the reflector 4. In a liquid crystal projector that uses a normal ellipsoidal mirror reflector as a reflector, a relay lens is provided between the light source unit and the liquid crystal display panel, and the reflected light from the reflector is corrected to parallel light by this relay lens and the liquid crystal is corrected. It leads to the display panel. Further, in FIG. 6, 5 is an eccentric Fresnel lens provided on the front side of the liquid crystal display panel 1, and 6 is the liquid crystal display panel 1.
Is a projection lens provided in front of the liquid crystal display panel 1, that is, the display image of the liquid crystal display panel 1 is directed in a predetermined direction by the eccentric Fresnel lens 5 and is condensed on the projection lens 6 to be projected. The image is enlarged by the lens 6 and projected on the screen S surface. The liquid crystal display panel 1 is of a TN (twisted nematic) type, and the liquid crystal display panel 1 is arranged with respect to the optical axis on the light source side so that the incidence efficiency of the illumination light incident from the back side thereof is maximized. It is provided at a predetermined angle.

That is, this liquid crystal projector magnifies and projects the display image of the liquid crystal display panel on the screen surface, and according to this liquid crystal projector, it is not necessary to insert and remove the slide film as in a normal projector using a slide film. Also, a moving image such as a television image can be projected on the screen surface.

[Problems to be Solved by the Invention] However, in the conventional liquid crystal projector, the light traveling from the light source lamp 3 to the reflector 4 is reflected toward the liquid crystal display panel 1 by the reflector 4, but the light source lamp 3
Since the light traveling in the direction without the reflector 4 spreads radially as it is, most of the light other than the light traveling to the liquid crystal display panel 1 will be diffused to the surroundings. Since the amount of light incident on the liquid crystal display panel 1 is considerably smaller than the amount of light generated by the light source lamp 3, the conventional liquid crystal projector is
The liquid crystal display panel has a low display brightness, which causes a problem that the projected image projected on the screen surface is dark. Also,
Generally, a high-intensity xenon lamp is used as the light source lamp 3 of the liquid crystal projector. However, since the light generated by the xenon lamp or the like contains electromagnetic waves, the conventional liquid crystal projector described above has There is also a problem that a digital circuit such as a display driving circuit provided may be affected by an electromagnetic wave in the light radially spreading from the light source lamp 3 to cause a malfunction.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to enable the illumination light from the light source lamp to be guided to the liquid crystal display panel without being diffused to the surroundings. It is possible to efficiently illuminate the liquid crystal display panel and project a bright image with high brightness on the screen surface, and even if the light generated by the light source lamp contains electromagnetic waves, the digital circuit in the projector affects the electromagnetic waves. An object of the present invention is to provide a liquid crystal projector that can prevent the reception of the liquid crystal.

[Means for Solving the Problem] The present invention comprises a light source section, a liquid crystal display panel, and a projection means, and liquid crystal for projecting and displaying the light from the light source into the liquid crystal display panel by the projection means. In the projector, a tubular light guide pipe is provided continuously from the reflector of the light source unit to the vicinity of the liquid crystal display panel,
A ventilation hole is provided on the reflector side of the light guide pipe, and light from the light source is guided to the liquid crystal display panel through the light guide pipe.

[Operation] By doing this, not only the reflected light from the reflector and the light directly from the light source lamp to the liquid crystal display panel,
Light that radially spreads from the light source lamp is also guided to the liquid crystal display panel by being prevented from diffusing to the surroundings by the light guide pipe, so that the liquid crystal display panel can be efficiently illuminated and therefore the display brightness of the liquid crystal display panel can be increased. The projector can project a bright image with high brightness on the screen surface, and since the light from the light source lamp does not radiate to the surroundings, even if the light generated by the light source lamp contains electromagnetic waves, the projector The internal digital circuit is not affected by the electromagnetic waves, and even if the light source lamp of the light source unit should burst, fragments can be prevented from scattering into the case and damaging the device. Moreover, since the ventilation holes are provided on the reflector side of the light guide pipe, cooling can be performed.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is a case of a liquid crystal projector, and a projection lens 26 having a plurality of optical lenses arranged side by side in a lens barrel is provided on the front surface of the case 10. Reference numeral 21 denotes a transmissive dot-matrix liquid crystal display panel which is arranged inside the case 10 so as to face the projection lens 26. The projection lens 26 is provided on the front side of the liquid crystal display panel 21 with its transmitted light directed in a predetermined direction. Decentered Fresnel lens 25
Is provided. Further, on the rear end side of the case 10, a light source unit 22 is provided which is located behind the liquid crystal display panel 21 and illuminates the liquid crystal display panel 21 from the back side.
The light source unit 22 includes a light source lamp 23 such as a xenon lamp,
It is composed of a reflector 24 that reflects the illumination light from the light source lamp 23 toward the back surface of the liquid crystal display panel 21,
The reflector 24 is a parabolic reflector that reflects the light from the light source lamp 23 as parallel light.

Further, 27 is a cylindrical light guide pipe which is provided from the light source part 22 toward the liquid crystal display panel 21 and whose both ends are open. The inner peripheral surface of the light guide pipe 27 reflects light appropriately. Has been plated with chrome. This light guide pipe 27
Is a taper cylinder with a smaller diameter toward the tip,
The diameter of the base end is substantially the same as the outer diameter of the parabolic reflector 24, and the inner diameter of the tip is slightly larger than the circumscribed circle of the display screen of the liquid crystal display panel 21. The light guide pipe 27 has a peripheral edge portion at the base end thereof, and a flange portion 27a formed on the outer periphery thereof is fixed to the flange portion 24a formed on the outer peripheral edge of the parabolic reflector 24 with screws 28, 28. It is connected to the outer peripheral portion and is provided in a state in which the open surface of the tip is closely opposed to the back surface of the liquid crystal display panel 21. The light guide pipe 27 is for guiding the illumination light from the light source unit 22 to the liquid crystal display panel 21 without being diffused to the surroundings, and is parallel to the optical axis reflected by the parabolic reflector 24 and directed to the liquid crystal display panel 21. The parallel light and the light directly coming from the light source lamp 23 to the liquid crystal display panel 21 are guided by the light guiding pipe 27.
Light that goes straight inside the liquid crystal display panel 21 and that spreads radially from the light source lamp 23 is guided to the tip side of the light guide pipe 27 while being reflected by the inner peripheral surface of the light guide pipe 27, and a liquid crystal display It is incident on the panel 21.

Further, at the base end side of the light guide pipe 27, a cooling air suction port 29a and a cooling air suction port 29b are provided on the lower surface and the upper surface thereof as shown in FIG. 1 and FIG. Suction port 29a
A blower 30 for cooling is provided below. The blower 30 blows air in the case 10 from the air suction port 29a into the light guide pipe 27 to cool the light source unit 22 and the light guide pipe 27 from the inside, and the cooling air is discharged from the exhaust hole 29b. Is discharged.

On the other hand, in FIG. 1, 31 is a display panel cooler provided on the back surface side of the liquid crystal display panel 21. As shown in FIGS. 3 and 4, the display panel cooler 31 has a display screen 21 of the liquid crystal display panel 21 on the back surface of the liquid crystal display panel 21.
A frame 32, which is sufficiently larger than a, is attached, and a cooling box body 31a in the form of a closed box formed by attaching a transparent plate 33 to the light source side of the frame 32 is filled with a cooling liquid a such as an ethylene glycol aqueous solution. The heat pipes 34, 34 are inserted on both sides inside the cooler body 31a while avoiding the display screen 21a portion of the liquid crystal display panel 21. The heat pipes 34, 34 are obtained by enclosing a volatile refrigerant in a pipe whose both ends are closed, and the cooler body 31a of the heat pipes 34, 34.
Air-cooled fins 35, 35 are attached to the part protruding upward. The refrigerant in the heat pipes 34, 34 is cooled by the cooler body 3
The temperature rises in the heat pipe 34 due to the heat in the la 1a, is cooled by the air in the case 10 in the air-cooled fin portion, and descends again to the cooler body 31a side.
The cooling liquid a therein is constantly cooled by the convection circulation of the refrigerant in the heat pipes 34. That is, the display panel cooler 31 is for cooling the liquid crystal display panel 21 from the back side thereof, and the illumination light from the light source unit 22 is made incident on the liquid crystal display panel 21 through the display panel cooler 31. By doing so, it is possible to prevent the liquid crystal display panel 21, which is weak against heat, from rising in temperature due to the heat of the illumination light, and prevent the heat destruction thereof. The transparent plate 3 on the light source side of the cooler body 35a
3 may be an ordinary transparent plate such as glass, but this transparent plate 33
If is an infrared absorption filter or an infrared reflection filter, it is possible to cut infrared rays in the illumination light,
Further, the temperature rise of the liquid crystal display panel 21 can be prevented more effectively.

In FIG. 1, 11 is an outside air intake port provided on the front surface of the case 10, and 12 is an exhaust port provided on the rear end side upper surface of the case 10. The exhaust port 12 has an outside air intake port. A blower fan 13 that sucks the outside air from 11 and exhausts it from the exhaust port 12 is provided.

Therefore, in this liquid crystal projector, as described above, the cylindrical light guide pipe 27 is provided from the light source unit 22 toward the liquid crystal display panel 21, and the illumination light from the light source unit 22 is guided inside the light guide pipe 27. Since the light is guided to the liquid crystal display panel 21 through the
Not only the light directly going from 23 to the liquid crystal display panel 21, but also the light radially spreading from the light source lamp 23 is guided to the liquid crystal display panel 21 by being prevented from being diffused to the surroundings by the light guide pipe 27. Therefore, according to this liquid crystal projector, most of this illumination light can be made incident on the liquid crystal display panel 21 without loss of the illumination light from the light source lamp 23, and the liquid crystal display panel 21 can be efficiently illuminated. It is possible to increase the display brightness of the panel 21 and project a bright image with high brightness on the screen S surface. Moreover, in this liquid crystal projector, since the light from the light source lamp 23 does not escape to the surroundings, the light source lamp 23
Even if the generated light includes electromagnetic waves, the digital circuit in the projector (not shown but provided in the case 10) is not affected by the electromagnetic waves. Even if a xenon lamp or the like containing electromagnetic waves is used, there is no fear that the digital circuit in the projector malfunctions due to the electromagnetic waves in the generated light.

In the above embodiment, the light guide pipe 27 has a tapered cylindrical shape, but the light guide pipe 27 may have a straight cylindrical shape as shown in FIG. The light source unit 22 including the light source lamp 23 and the reflector 24 may be housed in the light guide pipe 27 by extending 27 to the base end side.

In the above embodiment, the reflector 24 of the light source unit 22 is a parabolic reflector that reflects the light from the light source lamp 23 to the liquid crystal display panel 21 side as parallel light, but this reflector 24 may be a normal elliptical mirror reflector. In that case, a relay lens for correcting the illumination light from the light source unit 22 into parallel light may be provided inside the light guide pipe 27 or between the tip of the light guide pipe 27 and the liquid crystal display panel 21.

[Advantages of the Invention] The present invention provides a liquid crystal projector comprising a light source section, a liquid crystal display panel, and a projection means, wherein light from the light source is incident on the liquid crystal display panel and projected and displayed by the projection means. A cylindrical light guide pipe is provided continuously from the reflector of the light source section to the vicinity of the liquid crystal display panel,
Since a ventilation hole is provided on the reflector side of the light guide pipe to guide the light from the light source to the liquid crystal display panel through the light guide pipe, the light reflected by the reflector and the liquid crystal display panel directly from the light source lamp. Not only the light that goes toward, but also the light that radially spreads from the light source lamp can be guided to the liquid crystal display panel by preventing the light from being diffused to the surroundings by the light guide pipe, and therefore, the liquid crystal display panel can be efficiently illuminated. The display brightness of the liquid crystal display panel can be increased to project a bright image with high brightness on the screen surface, and since the light from the light source lamp does not radiate to the surroundings, electromagnetic waves are generated in the light generated by the light source lamp. , The digital circuit in the projector is not affected by electromagnetic waves, and even if Even the lamp ruptures, prevent also debris destroy equipment scattered in the case. Moreover,
Since a ventilation hole is provided on the reflector side of the light guide pipe,
Cooling can be done.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention.
FIG. 1 is a vertical side view of a liquid crystal projector, and FIG.
A cross-sectional view taken along the line AA of FIG. 3, FIG. 3 and FIG. 4 are a partially cutaway front view and a vertical side view of a display panel cooler provided on the back side of a liquid crystal display panel. FIG. 5 is a vertical sectional side view of a light guide pipe showing another embodiment of the present invention. Sixth
The figure is a principle configuration diagram of a conventional liquid crystal projector. 21 ... Liquid crystal display panel, 22 ... Light source section, 23 ... Light source lamp, 24
... parabolic reflector, 26 ... projection lens, 27 ... light guiding pipe, 31 ... display panel cooler, S ... screen.

Claims (1)

[Claims] 1. A liquid crystal projector comprising a light source section, a liquid crystal display panel, and a projection means, wherein light from the light source is incident on the liquid crystal display panel and projected and displayed by the projection means. From the light guide pipe to the vicinity of the liquid crystal display panel continuously, the light from the light source is guided to the liquid crystal display panel through the light guide pipe, and on the reflector side of the light guide pipe. A liquid crystal projector having a ventilation hole.