JP2001215621A - Projection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cooling efficiency of a light source section of a projection type liquid crystal display device without affecting the downsizing of the device. SOLUTION: The neck part of a glass reflector 2 for holding the light source 1 is provided with a heat radiation plate 10a of a cylindrical shape and planar heat radiation fins 10b are mounted at this heat radiation plate 10a radially to the optical axis of the light source 1. The heat from the light source 1 is conducted via the glass reflector 2 and the heat radiation plate 10a to the heat radiation fins 10b. The heat is radiated from the heat radiation fins 10b to the circumference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type liquid crystal for displaying an image based on an output signal from a personal computer, a television signal, or a video signal reproduced from a storage medium such as a DVD on a screen in an enlarged manner. The present invention relates to a display device, and more particularly, to a projection type liquid crystal display device improved to improve the cooling efficiency of a light source unit that supplies light to a liquid crystal display element.

[0002]

2. Description of the Related Art Conventionally, as a projection type display device, there is a so-called projector which irradiates an optical image signal formed on a light valve by an illumination means and enlarges and projects the optical image on a screen by the projection means. is there. As the light valve, a device using a liquid crystal display element is called a projection type liquid crystal display device, a so-called liquid crystal projector, and many devices have been proposed.

[0003] Twisted liquid crystal display devices are one of the liquid crystal display devices.
The nematic (TN) type liquid crystal display device is configured by injecting liquid crystal between a pair of transparent substrates having a transparent electrode film, and the polarization directions are different from each other by 90 degrees before and after the liquid crystal display device. By disposing two polarizing elements and combining the action of rotating the plane of polarization by the electro-optic effect of the liquid crystal and the action of selecting the polarization component of the polarizing elements, the amount of transmitted incident light is controlled to display image information. It is configured as follows.

[0004] Such a projection type liquid crystal display device is capable of not only displaying an image by a reproduction signal from a storage medium such as a television signal or a DVD, but also displaying an image from a personal computer.
Since an image can be displayed by the C signal, opportunities for utilizing it for presentation are increasing. With the increasing use of such projection-type liquid crystal display devices for presentation, the size and weight of the projection-type liquid crystal display device have been reduced due to the demand for portability. Also, give a presentation,
Higher brightness display images are also being promoted so that the venue can be kept bright.

[0005] In order to increase the brightness of the display image of the projection type liquid crystal display device, it is necessary to increase the power supplied from the light source power supply substrate to the light source, so that the power consumption of the light source increases. As the power consumption of the light source increases, the amount of heat generated by the light source increases, and the temperature of the light source increases. The heat generated by the light source affects the life of the light source, and also affects the components of each part in the projection type liquid crystal display device as the size of the projection type liquid crystal display device is reduced.

The structure of the light source unit will be described in detail. The light source includes a light emitting unit and a glass reflecting mirror (hereinafter, referred to as a glass reflector) for irradiating light emitted from the light source to a target irradiation surface. Be composed. This glass reflector is
The diameter on the side opposite to the light emitting direction is smaller than the light emitting opening, and forms a neck. The light source is held at the neck. In addition, the glass reflector is subjected to dichroic processing so as to transmit, without reflecting, far-infrared light and ultraviolet light other than visible light, which is unnecessary light. This is because these unnecessary lights are thermally converted by optical components such as a liquid crystal panel and a polarizing plate and affect the components and the like.

The power supply from the light source power supply board to the light source is performed by two electric wires from the light source power supply board. One of them is connected to a metal fixture fixed on the glass reflector by caulking, etc., with screws, etc.
The book is fixed to the end of the rear bracket constituting the light source by a nut or the like via a mounting bracket. The light source emits light by the electric power supplied by the two electric wires.

In such a conventional cooling structure of the light source unit of the projection type liquid crystal display device, the cooling of the light source unit is constituted by a cooling fan near the light source because the output of the light source is large. A mounting bracket attached to the end of the rear bracket constituting the light source for connecting an electric wire from the power source board for the light source plays a role of a heat sink for cooling the light source.

[0009]

As described above, if an attempt is made to increase the brightness of the display image of the projection type liquid crystal display device,
Heat generation in the light source section becomes a bigger problem. If the rotation speed of the cooling fan is increased to improve the cooling efficiency of the light source in response to the high temperature of the light source unit, the problem of noise due to wind noise increases. On the other hand, if the size of the mounting bracket that also functions as a heat sink attached to the end of the rear bracket that constitutes the light source and that is connected to the electric wire from the power supply board for the light source is increased, the flow of the air from the cooling fan will be blocked, Impedes the cooling efficiency of the light source. In addition, high voltage is applied to the mounting bracket from the power supply board for the light source, and if the mounting bracket is enlarged, the insulation distance between surrounding components is reduced, and the clearance between the mounting bracket and surrounding components must be increased. This is incompatible with the reduction in size and weight of the projection type liquid crystal display device. In addition, when the size of the mounting bracket is increased, an area for receiving unnecessary light transmitted from the light source through the glass reflector also increases, and the temperature of the mounting bracket increases due to the unnecessary light, and the effect of the mounting bracket as a heat radiating plate is reduced.

The present invention has been made in view of such problems of the prior art, and an object thereof is to efficiently cool a light source unit without adversely affecting the size and weight of an apparatus. It is an object of the present invention to provide a projection type liquid crystal display device that can be used.

[0011]

In order to achieve the object of the present invention, a projection type liquid crystal display device according to the present invention holds a light source, and reflects the light emitted from the light source while reflecting the light source. A projection type liquid crystal display having a reflector, configured to guide light from the light source and light reflected from the reflector to a liquid crystal display element, and to project an image transmitted by the liquid crystal display device to display an image. The apparatus is characterized in that the reflector is provided with a heat radiating means for releasing the heat of the light source.

The heat radiating means is formed in a cylindrical heat radiating plate attached to a neck portion of the reflector which holds the light source, and is formed on the heat radiating plate and extends in a radial direction of the heat radiating plate. Radiating fins. Further, a plurality of the heat radiating fins may be provided so as to be radially attached to the center axis direction of the heat radiating plate.

The radiating fins may be plate-shaped, and may be attached to the radiating plate such that a width direction of the fins is parallel to a direction of cooling air supplied by the cooling fan. . Further, the radiation fin may be attached to the heat radiating plate such that a width direction of the radiation fin is parallel to an optical axis direction of the light source.

That is, in the present invention, focusing on the insulation distance around the light source, in order to secure the insulation distance, a radiator plate and a radiator fin for cooling the light source are provided on the reflector to which a high voltage from the power source substrate for the light source is not applied. It is characterized by being attached. If the heat radiating plate and the heat radiating fins are electrically insulated, the heat radiating plate and the heat radiating fins may be made large or the insulation distance from the surroundings may not be considered much. Further, by making the width direction of the radiating fins of the radiating plate attached to the reflector parallel to the direction of the flow of the cooling air around the light source by the cooling fan, it is possible to prevent the flow of the air around the light source from being interrupted, and By increasing the number of radiation fins, the cooling efficiency of the light source can be improved. Also, by making the width direction of the radiating fins and the light emitting direction of the light source (the optical axis direction of the light source) the same, it is possible to reduce the area in which this radiating fan receives unnecessary light transmitted through the reflector, To prevent the temperature from becoming high.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention and is a cross-sectional view of a light source section of a projection type liquid crystal display device, which is parallel to an optical axis direction of the light source. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 and is orthogonal to the optical axis direction of the light source.

In FIG. 1, reference numeral 1 denotes a light source such as a metal halide, for example, and 2 denotes a glass reflector which is a reflecting mirror to which an ellipsoidal mirror or the like is applied, for example, since a glass reflector is mainly used, a glass reflector is used here. However, it goes without saying that the present invention can be applied to reflectors other than glass.) The glass reflector 2 has a smaller diameter at the neck, which is the end in the direction opposite to the light emission direction, than at the opening end face, which is the light emission surface, and holds the light source 1 at the neck. Also,
The glass reflector 2 is fixed to the emission surface side of the lamp case 3 using a spring or the like. 4a and 4b are power supply leads for supplying power to the light source 1, and the power supply leads 4a and 4b are connected to a light source power supply board. Further, the power supply lead 4a is attached with a nut or the like via a mounting bracket 6a in order to connect the light source 1 with the light source rear portion 5. A cooling fan 7 is provided near the lamp case 3 for cooling the light source 1, and generates cooling air W around the light source 1 to cool the light source unit. Further, the cooling air W is exhausted from the heat radiation holes 9 provided in the housing 8.

Reference numeral 10a denotes a heat radiating plate for cooling the light source 1, which has a cylindrical shape surrounding the periphery of the neck of the glass reflector 2. The heat radiating plate 10 a is in thermal contact with the neck of the glass reflector 2, and the heat of the light source 1 is conducted through the glass reflector 2. Further, on the heat radiating plate 10a, plate-shaped heat radiating fins 10b formed extending in the radial direction of the heat radiating plate 10a are arranged radially with respect to the optical axis direction of the light source along the circumferential direction of the heat radiating plate 10a. Multiple sheets are attached. The heat radiation fin 10b cools the light source unit (including the light source 1 and the glass reflector 2) by further transmitting the heat of the light source 1 transmitted to the heat radiation plate 10a and radiating the heat to the surroundings.

L1 indicates effective light used for projection onto the liquid crystal element, and L2 indicates unnecessary infrared and ultraviolet light other than visible light that passes through the glass reflector 2. Reference numeral 6b denotes a virtual mounting bracket when the mounting bracket 6a is enlarged, and is indicated by a two-dot chain line. δ is the virtual mounting bracket 6
It shows the insulation distance between b and the surroundings.

The cooling structure of the light source in the projection type liquid crystal display device of the present invention having the above configuration will be described. As described above, conventionally, the mounting bracket 6a functions as a cooling radiator for the light source 1, and when the mounting bracket 6a is enlarged, the mounting bracket 6a has the shape of the virtual mounting bracket 6b. At this time, the cooling air W has a narrow air path due to the virtual mounting bracket 6b, and has a negative effect on the heat radiation effect. Further, the area where the virtual mounting bracket 6b receives far-infrared light other than visible light and unnecessary light L2 of ultraviolet light is larger than the mounting bracket 6a, and the light source 1
The temperature of the virtual mounting bracket 6b rises due to the energy given by the unnecessary light L2 other than the amount of heat given by the virtual attachment.
For the above two reasons, even if the area of the mounting bracket 6a is increased, a great improvement in cooling efficiency cannot be expected. When the mounting bracket 6a is made larger like the virtual mounting bracket 6b,
The insulation distance δ between the virtual mounting bracket 6b and the surroundings decreases, and the lamp case 3 needs to be increased, which is against the trend of miniaturization of the projection type liquid crystal display device.

In the present invention, the heat radiating plate 10a and the heat radiating fins 10b are attached to the glass reflector 2, which is an insulator, and the heat of the light source 1 transmitted through the glass reflector is radiated to the surroundings. Board 10a
There is no need to consider the insulation distance between the radiation fin 10b and the lamp case 3. That is, in the present invention, the radiation fin 10b to which the heat of the light source 1 is transmitted is provided in the glass reflector 2, so that the heat radiation area is increased without impairing the miniaturization of the projection type liquid crystal display device, and the cooling efficiency of the light source unit is reduced. Can be enhanced. Further, the width direction of the radiation fin 10b is made parallel to the direction of the cooling air W so as not to become a resistance to the cooling air W generated by the cooling fan 7. Therefore, the cooling air W is supplied to the cooling fin 10b.
And the cooling efficiency of the light source 1 is further improved. Further, if the radiation fins 10b are attached so that the resistance of the cooling air W is reduced, the resistance to the cooling air W is small even if the number of the radiation fins 10b is increased, and the radiation efficiency increases with the increase in the number of the radiation fins 10b. I do.

Also, as shown in FIG.
If the width direction of b and the optical axis direction of the light source 1 are made parallel, the emission direction of the unnecessary light L2 of far infrared and ultraviolet light other than visible light and the width direction of the radiation fin 10b become substantially parallel, and the unnecessary light L2 The area of the radiation fin 10b that receives the light can also be reduced. Therefore, with such arrangement of the radiation fins 10b, it is possible to prevent the temperature rise of the radiation fins 10b and the radiation plate 10a due to the unnecessary light L2.

FIG. 3 shows the cooling effect when the wind speed of the cooling air W in FIG. 1 is changed. No. No. 1 shows the effect when the heat radiating plate 10a and the heat radiating fin 10b are provided. 2 shows the effect when there is no radiator plate 10a and radiator fin 10b.
That is, No. No. 1 is the effect of the cooling structure of the conventional light source 1, and No. 1 2 shows the effect of the cooling structure of the light source 1 according to the present invention.

No. As shown in FIG. 1, in the conventional cooling structure, even if the speed of the cooling air W generated by the cooling fan 7 is increased, the amount of heat taken from the light source rear portion 5 does not change much. While N
o. No. 2 in the cooling structure of the present invention as shown in FIG. It is possible to take at least three times or more the amount of heat from the light source rear part 5 with respect to 1. Further, as the wind speed of the cooling air W generated by the cooling fan 7 is increased, the amount of heat taken from the rear portion 5 of the light source also increases proportionally.

In the present invention, the width direction of the cooling fin 10b is defined as the flow direction of the cooling air (ie, the optical axis direction of the light source 1).
However, the light source 1 may be attached at a predetermined angle with respect to the optical axis direction of the light source 1 so as not to hinder the flow of the cooling air. Further, the cooling fins 10b may be provided with uneven grooves or projections on the surface thereof to generate turbulent flow on the surfaces of the cooling fins 10b, thereby increasing the cooling efficiency.

[0025]

As described above, according to the present invention, the cooling efficiency of the light source can be improved without hindering the miniaturization of the device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a light source unit according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a graph showing an example of a cooling effect of a light source according to the present invention.

[Explanation of symbols]

1 ... light source, 2 ... glass reflector, 3 ... lamp house,
4a, 4b: power lead, 5: rear of light source, 6a: mounting bracket, 6b: virtual mounting bracket, 7: cooling fan, 8 ...
Casing, 9: heat dissipation hole, 10a: heat dissipation plate, 10b: heat dissipation fin, L1: effective light, L2: unnecessary light, W: cooling air, δ: insulation distance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/74 G02F 1/1335 530 (72) Inventor Tadao Miyasaka 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Japan Stock Hitachi, Ltd. Digital Media System Division F-term (reference) 2H091 FA14Z FA41Z LA04 MA07 5C058 AB06 EA13 EA26 EA52 5C096 AA16 AA22 BA05 CC09 CC33 5G435 AA12 AA18 BB12 BB17 DD06 DD09

Claims (6)

[Claims] And a reflector for holding the light source and reflecting the light emitted from the light source, guiding the light from the light source and the reflected light from the reflector to a liquid crystal display element. In a projection type liquid crystal display device configured to display an image by projecting light transmitted through the liquid crystal display device, the reflector is provided with a heat radiating unit for releasing heat of the light source. Projection type liquid crystal display device. 2. The projection type liquid crystal display device according to claim 1, further comprising a cooling fan for supplying cooling air around at least said reflector and said heat radiating means. apparatus. 3. The heat radiating means includes: a cylindrical heat radiating plate attached to a neck portion of the reflector, which is a portion holding the light source; a heat radiating plate attached to the heat radiating plate, and extending in a radial direction of the heat radiating plate. 3. The projection type liquid crystal display device according to claim 2, further comprising: a radiation fin formed by forming. 4. The heat radiating means includes: a cylindrical heat radiating plate attached to a neck portion of the reflector, which is a portion holding the light source; 3. The projection type liquid crystal display device according to claim 2, comprising a plurality of radiation fins radially attached. 5. The radiating fin has a plate shape and is attached to the radiating plate such that a width direction of the radiating fin is parallel to a direction of cooling air supplied by the cooling fan. The projection type liquid crystal display device according to claim 3 or 4, wherein: 6. The radiation fin according to claim 3, wherein the radiation fin has a plate shape and is attached to the radiation plate so that a width direction of the radiation fin is parallel to an optical axis direction of the light source. Or a projection type liquid crystal display device according to item 4.