KR100196912B1 - Projection type television apparatus - Google Patents

Abstract

In order to prevent brightness and contrast of a display device from being degraded by attaching dust contained in air introduced through an air inlet of a projection television device to a display device, And a filter device capable of being filtered.

Description

Projection television device

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a projection type television apparatus, and more particularly, to a projection type television apparatus in which dusts contained in air introduced through an air inlet of a projection type television apparatus are attached to a display element, And a filter device capable of filtering fine dust even at an air inlet port to prevent dust from entering the air inlet.

In general, a projection type television apparatus normally uses a combination of a high-luminance display element and an optical system in a suitable manner in a manner suitable for a large display element which can not be realized by a general display element. As a display device, a cathode ray tube (CRT), a liquid crystal display (LCD), and a liquid crystal light valve (LCLV) mixed with the characteristics of a CRT and an LCD are used. Since the image formed and output from these display elements is finally enlarged and displayed on the screen, it must have high brightness and high contrast.

On the other hand, in order to have such a high brightness and high contrast, the CRT is driven with a high cathode current, and in the case of an LCD, a high-brightness backlight is used. Since the projection type television set is usually housed in a closed housing as one unit, when the display elements of high luminance and high contrast are used as described above, the temperature in the housing gradually increases, and as a result, the display elements are adversely affected.

Therefore, conventionally, a cooling device is used to reduce the temperature increase. In the case of a CRT, a refrigerant-based refrigerant has been mainly used to reduce the heat generated by the CRT itself. For example, in Korean Patent Publication No. 92-10663 (Dec. 12, 1992), a display screen is provided on the inner side of a display window and a light transmissive second window is provided on a front side of the window, Characterized in that the cooling liquid flows from at least one inlet opening to at least one outlet opening through the space of the cooling liquid, and the cooling liquid flows by the temperature difference of the cooling liquid.

In the case of LCDs, a simple and inexpensive air cooling system has been widely used. Referring to Fig. 1, a conventional projection television apparatus is schematically shown. As shown in FIG. 1, a screen 13 for displaying an image to be finally viewed is attached to a front surface of a closed housing 11, as shown in FIG. Inside the housing 11, a display device, an optical system, and a cooling device are provided in association with each other. The display device includes an LCD panel 17 as an image source, a backlight 19 disposed at a predetermined distance behind the LCD panel 17, and a backlight 19 formed between the LCD panel 17 and the backlight 19, And a condensing lens 21 for making the incident light incident on the LCD panel 17 in parallel. The optical system includes a first reflective mirror 25 provided at a predetermined inclination below the LCD panel 17, a projection lens 27 for focusing an image reflected from the first reflective mirror, And a second reflection mirror 29 and a third reflection mirror 30 which are disposed so as to face each other with a predetermined slope in order to magnify and display the image on the screen 13. The cooling apparatus includes a cooling fan 23 for applying external air to the LCD panel 17 through an air inlet 15 formed at the lower portion of the rear surface of the housing 13.

The operation of the conventional projection type television apparatus thus constructed and the function of the cooling apparatus will be described below.

When predetermined image information is applied to the LCD panel 17 and power is applied to the backlight 19 to emit light, light is incident on the LCD panel 17 through the condenser lens 21 in parallel, (17). Thereafter, the image displayed on the LCD panel 17 is reflected by the first reflecting mirror 25 and is incident on the projection lens 27. The projection lens 27 focuses the incident image, ). The image is then magnified and displayed on the screen 13 through the second reflective mirror 29 and the opposing third reflective mirror 30.

As described above, since the image formed on the LCD panel 17 is enlarged while passing through the optical system and displayed on the screen 13, the image must have high brightness. For this purpose, the backlight 19 used as the light source of the LCD panel 17, Should emit high intensity light. Accordingly, a large amount of heat is generated along with high-luminance light. The incident-side polarizing plate absorbs unnecessary polarized light components of high-luminance light and generates heat, thereby raising the temperature of the liquid crystal cell of the LCD panel 17 by this heat. The cooling air is applied to the LCD panel 17 by rotating the cooling fan 23 in this case so that the outside air introduced into the air inlet 15 provided at the lower part of the rear side of the LCD panel 17 is forcedly supplied to the LCD panel 17 17).

However, the air cooling type cooling system as described above has some problems. That is, a large amount of fine dust exists in the air introduced into the housing through the air inlet, and the dusts introduced together with the air adhere to the surface of the LCD panel. As a result, when the projection type television apparatus is used for a certain period of time, there is a problem that the light transmittance is lowered due to the dust adhering to the surface of the LCD panel and the brightness and contrast are lowered. When the dust accumulates so much, There is an inconvenience to do. Also, due to accumulated dust, absorption of light is increased, and thus the surface temperature of the LCD panel abnormally rises and the liquid crystal cell of the LCD panel deteriorates. Also, a high-output cooling fan can be employed to prevent the temperature from rising, but in this case, there is a problem that the output is large and the noise is increased accordingly. Furthermore, considering that most of the projection-type television devices are used indoors, the noise issue may not be easily overlooked.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a projection type television apparatus capable of reducing the luminance and contrast of an LCD panel while at the same time blocking dust which increases the temperature of a liquid crystal cell of the LCD panel.

It is another object of the present invention to provide a projection type television apparatus capable of cooling an LCD panel more efficiently without increasing noise.

1 is a cross-sectional view schematically showing a conventional projection television apparatus;

2 is a cross-sectional view schematically showing a projection television apparatus according to the present invention.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a display device comprising: a sealed housing having a screen on one side and an air inlet on the other side; A projection television apparatus comprising an optical system that is optically coupled to a display device and displays the image on the screen, the projection type television apparatus comprising: a filter device for filtering dust contained in air introduced into the air inlet on the air inlet side .

Hereinafter, an embodiment of the projection-type television apparatus according to the present invention will be described with reference to FIG. Hereinafter, the same components are given the same reference numerals.

2, a projection television apparatus according to the present invention is schematically shown. As shown in FIG. 1, a screen 13 for displaying an image to be finally viewed is attached to a front surface of a closed housing 11, as shown in FIG. Inside the housing 11, a display device, an optical system, and a cooling device are provided in association with each other. The display device includes an LCD panel 17 as an image source, a backlight 19 disposed at a predetermined distance behind the LCD panel 17, and a backlight 19 formed between the LCD panel 17 and the backlight 19, And a condensing lens 21 for making the incident light incident on the LCD panel 17 in parallel. The optical system includes a first reflective mirror 25 provided at a predetermined inclination below the LCD panel 17, a projection lens 27 for focusing an image reflected from the first reflective mirror, And a second reflection mirror 29 and a third reflection mirror 30 which are disposed so as to face each other with a predetermined slope in order to magnify and display the image on the screen 13. The cooling device includes a first cooling fan 23 installed adjacent to the LCD panel 17 to apply the outside air introduced into the air inlet 15 formed in the lower portion of the rear surface of the housing 13 to the LCD panel 17, And a second cooling fan 40 installed in the air inlet 45. Preferably, the size of the air inlet 45 is larger than the size of the conventional air inlet 15. Preferably, the longitudinal directions of the shafts for driving the first and second cooling fans are perpendicular to each other.

In addition, according to the present invention, a filter device 42 for filtering the dust contained in the inflow air is provided on the front surface of the air inlet 45. Preferably, the filtering ability of the filter device 72 can filter even minute dust of 1 μm or less, and an ozone filter, a carbon filter, an electrostatic dust collecting filter, a high performance paper filter, a fiber filter, or the like can be used. The filter device 42 may be attached to the second cooling fan 40 or may be detachably attached to the air inlet 42.

Further, a grill-shaped exhaust port 55 is formed in the lower part of the front surface of the housing.

The operation of the projection type television apparatus according to the present invention and the function of the cooling apparatus will be described as follows.

As described above, when predetermined image information is applied to the LCD panel 17 and power is applied to the backlight 19 to emit light, the light is parallel to the LCD panel 17 through the condenser lens 21 And an image is displayed on the LCD panel 17. [ Thereafter, the image displayed on the LCD panel 17 is reflected by the first reflecting mirror 25 and is incident on the projection lens 27. The projection lens 27 focuses the incident image, ). The image is then magnified and displayed on the screen 13 through the second reflective mirror 29 and the opposing third reflective mirror 30.

As described above, since the image formed on the LCD panel 17 is enlarged while passing through the optical system and is displayed on the screen 13, the image must have high brightness. For this purpose, the backlight 19 used as the light source of the LCD panel 17, Should emit high intensity light. Accordingly, a large amount of heat is generated along with high-luminance light. The incident-side polarizing plate absorbs unnecessary polarized light components of high-luminance light and generates heat, thereby raising the temperature of the liquid crystal cell of the LCD panel 17. Accordingly, the first cooling fan 23 rotates to cool the LCD panel 17 using the introduced external air, and the internal air whose temperature has increased due to heat exchange with the LCD panel is discharged to the outside through the exhaust port 55.

At this time, the dust contained in the air flowing into the air inlet 45 is removed from the filter device 42 installed on the front surface of the air inlet 45, and then only clean air flows into the housing. Therefore, since dust does not exist in the air introduced into the housing 11, the brightness and contrast of the projection type television set are lowered by dust, and dust adheres to the LCD panel to increase light absorption, So that the liquid crystal cell of the LCD panel can be prevented from being deteriorated. Here, when the dust is removed from the filter device 42, the flow rate of the air is lowered by the filter device 42, but the flow is forcibly introduced by the second cooling fan 40, so that the flow velocity is rather increased. On the other hand, by providing the exhaust port 55 on the front side, the cooling efficiency can be further increased by limiting the flow of the cooling air to the lower portion of the housing where the main objects emitting heat are concentrated.

According to the present invention, the LCD panel 17 includes a first cooling fan 23 installed close to the LCD panel 17, and an air inlet 45 formed to be larger than the conventional air inlet, And is cooled by the second cooling fan (40). Therefore, even if the output of the first and second cooling fans is set to about 1/2 of that of the conventional one, the cooling efficiency is improved and the noise can be reduced to 1/2, have.

As described above, according to the present invention, since a filter device capable of filtering even minute dusts is installed in the air inlet, it is possible to prevent the dust and dirt from adhering to the surface of the LCD panel together with the air so that the brightness and contrast of the projection- It is possible to prevent the liquid crystal cell of the LCD panel from being deteriorated due to abnormal increase of the surface temperature of the LCD panel due to adhesion of dust and absorption of light. Furthermore, since the inflow air having passed through the filter device and having a reduced flow rate is forcibly introduced by using the second cooling fan to increase the flow velocity, the cooling efficiency can be increased. By providing at least two cooling fans, The noise can be reduced.

Various modifications may be made without departing from the basic spirit of the present invention. For example, the air inlet may be formed on the lower side of the rear surface, but the air inlet may be formed on the other side. It will be appreciated by those skilled in the art that other types of filters may be used in addition to the filters described above.

Claims (13)

A closed housing provided with a screen on one side and an air inlet on the other side; a display device that operates as an image source; a cooling device that cools the display device; A projection television apparatus having an optical system for displaying on a screen, Wherein a filter device for filtering dust contained in air introduced into the air inlet is formed on the air inlet side. The projection type television apparatus according to claim 1, wherein the filter device is capable of filtering against dust of 1 μm or less. 3. The projection-type television apparatus according to claim 2, wherein the filter device is an ozone filter. 3. The projection-type television apparatus according to claim 2, wherein the filter device is an electrostatic dust collecting filter. 3. The projection-type television apparatus according to claim 2, wherein the filter device is a carbon filter. 3. The projection-type television apparatus according to claim 2, wherein the filter device is a paper filter. 3. The projection-type television apparatus according to claim 2, wherein the filter device is a fiber filter. The projection type television set according to claim 1, wherein the cooling device comprises a first cooling fan provided on the display device side and a second cooling fan provided on the filter device side. 9. The projection-type television apparatus according to claim 8, wherein the longitudinal directions of the shafts for driving the first and second cooling fans are mutually perpendicular. The projection-type television apparatus according to claim 8, further comprising an air outlet formed on an opposite side of the air inlet. 11. The projection-type television apparatus according to any one of claims 1 to 10, wherein the display device is a cathode ray tube. 11. The projection-type television apparatus according to any one of claims 1 to 10, wherein the display device is an LCD. 11. The projection-type television apparatus according to any one of claims 1 to 10, wherein the display device is a liquid crystal light valve.