JP2002350806A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal projector which can efficiently remove dust in a liquid crystal panel part. SOLUTION: In the liquid crystal projector, beams emitted from a light source 10 are separated, beams transmitted through liquid crystal panels 3a, 3b, 3c are synthesized by a cross dichroic prism 1 and synthesized beam is enlarged and projected on a screen by a projection lens 11. The liquid crystal projector is provided with partition plates 6 each of which is opened upper and lower sides and is partitioned into a box shape below the cross dichroic prism 1 and respective liquid crystal panels, a fan 2 for cooling which is arranged below the partition plate 6 and a louver 5 which controls a blowing out position of cooling wind to the cross dichroic prism 1 and respective liquid crystal panels so as to close an upper opening of the partition plate 6. Quantity of the cooling wind to a prescribed liquid crystal panel part is automatically increased to efficiently remove dust attached to the liquid crystal panels when light source power is off and forced cooling is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector, and more particularly to a liquid crystal projector capable of efficiently removing dust and the like adhering to a liquid crystal panel using a forced air cooling time after a power supply is turned off and efficiently discharging the dust.

[0002]

2. Description of the Related Art FIGS. 4A and 4B are schematic views showing the structure of an optical unit 50 of a conventional liquid crystal projector, wherein FIG. 4A is a plan sectional view and FIG. 4B is a longitudinal sectional view of a liquid crystal panel. Light emitted from a light source 53 whose lamp or the like is covered with a reflecting mirror is blocked by a cut filter from ultraviolet and infrared rays, passes through a polarization conversion element 54 and a lens array 52 disposed in the housing 12, and mainly emits visible light. The component enters the mirror 62a. The red (R) light is separated and reflected by the mirror 62a, and passes through the liquid crystal panel 57b for red via the mirror 63a.

On the other hand, the light beam that has passed through the mirror 62a is separated into green (G) light and blue (B) light by the mirror 62b.
The reflected G light passes through the liquid crystal panel 57c for green. The B light transmitted through the mirror 62b is a lens, a mirror 63
b, the light passes through the liquid crystal panel 57a for blue via the lens and the mirror 63c. Liquid crystal panels 57a, 57b, 57c
Are mixed by the cross dichroic prism 51, enlarged by the projection lens 56, reflected by the rear mirror (not shown), and projected on the screen (not shown).

In order to reduce the heat of the liquid crystal panel inside the optical unit 50, as shown in FIG. 4 (b), it is air-cooled by a cooling fan 60 during operation. For a while after the power is turned off, the purpose of improving the re-lighting property of the lamp and the housing 1
For the purpose of lowering the temperature of No. 2, forced air cooling by a fan is performed. The cooling air is taken into the housing 55 by the fan 60 via the filter 61, passes through the rectifying fins 59, and is sent to the liquid crystal panel section in the area partitioned by the partition plate 58, and the liquid crystal panel and the cross dichroic prism Cool 51. The wind passing through the liquid crystal panel cools the inside of the other housing and is discharged to the outside.

[0005]

When the size of the filter 61 is reduced, the filter 61 becomes clogged or the air volume decreases, and the temperature inside the housing tends to rise. Therefore, a filter 61 having too fine a size cannot be used. . Therefore, invasion of dust into the housing is an inevitable problem.

[0006] Dust that has entered the housing adheres to the surface of the liquid crystal panel and degrades image quality. In order to prevent these, during normal operation, it is conceivable to fly these dusts by the air from a fan for air cooling.
It is necessary to increase the air volume, or to apply the wind to a place where dust tends to adhere, which increases noise during normal operation and hinders efficient reduction of the temperature inside the set.

As a technique for solving the above-mentioned problems, Japanese Patent Laid-Open Publication No. 2000-12224 discloses a technique in which a cooling fan removes dust during cooling which flows in from the outside with a filter, and further passes through a air conditioning fin to which an adhesive material is adhered. A method for removing dust and reducing the adhesion of dust to a liquid crystal panel is disclosed. Japanese Patent Application Laid-Open No. 2000-180816 discloses that dust is applied to the windward side of a cooling fan, and the dust is removed by an electrostatic filter provided on the leeward side, thereby reducing the adhesion of the dust to the liquid crystal panel. There is disclosed a method for causing this to occur.

However, in the technique disclosed in the former publication, if dust adheres to the adhesive of the air conditioning fins, the performance of the adhesive is reduced and the performance of removing the dust is reduced. Therefore, frequent replacement of the adhesive is necessary. there were. In the latter publication,
There are problems that the device becomes complicated and the device cannot be miniaturized.

Accordingly, the present invention is to solve the above-mentioned problems of the prior art and to provide a liquid crystal projector capable of efficiently removing and discharging dust inside the set.

[0010]

A liquid crystal projector according to the present invention comprises: means for separating light emitted from a light source into three primary colors;
Three liquid crystal panels provided at required positions of the optical axes of the respective lights and transmitting the separated light, a cross dichroic prism for combining the respective lights transmitted through the liquid crystal panel, A projection lens for magnifying the combined light and projecting the same on a screen, wherein the three liquid crystal panels face up and down with the cross dichroic prism facing three side faces of the cross dichroic prism. A cooling fan, which is disposed inside and below or above the cross dichroic prism and each of the liquid crystal panels, controls a blowing position of cooling air sent into the box body by the cooling fan to the cross dichroic prism and each of the liquid crystal panels. Opening / closing means for closing the box.

The opening and closing means includes four openable and closable doors for blowing out the cooling air corresponding to the cross dichroic prism and the respective liquid crystal panels, and the four doors can be independently opened and closed.

Further, the opening / closing means includes a door opening / closing control mechanism for blowing the cooling air to the liquid crystal panels in order. The opening / closing means is provided with a control mechanism that shuts off all of the doors after the power of the light source is turned off and the cooling fan is operated for a predetermined time, so that dust enters the liquid crystal panel unit after using the liquid crystal projector. Can be prevented.

In the liquid crystal projector of the present invention, a louver or a slide can be used as the opening / closing means.

[0014] The liquid crystal projector of the present invention can be provided with operation means for selecting the operation of the opening / closing means on an on-screen menu screen.

Further, in the liquid crystal projector according to the present invention, the cooling fan may be provided with a rotation speed control mechanism to increase the rotation speed of the cooling fan during forced air cooling time to further increase the amount of cooling air blown from the door. it can.

According to the liquid crystal projector of the present invention, the amount and intensity of the cooling air blown to the liquid crystal panel after the power source of the light source is turned off can be increased without installing an air nozzle as in the related art. The dust adhering to the surface can be mechanically and efficiently removed by the cooling air, and the performance can be prevented from deteriorating due to the dust adhering to the liquid crystal panel.

[0017]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view of a main part showing an embodiment of a liquid crystal projector according to the present invention.
0B is a cross-sectional plan view, FIG.
(C) is a perspective view of the louver portion.

Referring to FIG. 1, a liquid crystal projector according to the present invention includes a polarization conversion element 13, a lens array 14, a mirror 8a, and a mirror 8 for separating light emitted from a light source 10 in which a lamp or the like is covered with a reflecting mirror into three primary colors. 8b, 9a, 9b, 9c, etc., and a liquid crystal panel 3a for transmitting each separated light.
3b and 3c, a cross dichroic prism 1 for synthesizing light transmitted through each liquid crystal panel, and a projection lens 11 for enlarging the synthesized light and projecting it on a screen.

Each liquid crystal panel is arranged to face three side surfaces of the cross dichroic prism 1. The cross dichroic prism 1 and the liquid crystal panels 3a, 3b, 3c are composed of a partition plate 6, and are arranged in a box whose top and bottom are open. A cooling fan 2 is provided below the box of the partition plate 6. Reference numeral 12 indicates a housing.

A louver 5 (opening / closing means) having a door which can be opened and closed so as to close the opening of the box, just below the cross dichroic prism 1 and the liquid crystal panel of the box of the partition plate 6.
Are arranged to control the blowing position of the cooling air sent from below to the inside of the box by the fan 2 to the cross dichroic prism 1 and each liquid crystal panel.

While the louver 5 is driving the liquid crystal projector, the entire door is opened as shown in FIG. As shown in FIG. 1 (c), the louver 5 is provided with liquid crystal panels 3a, 3b,
and c, and an opening / closing door 5d provided near the lower surface of the cross dichroic prism 1 is provided.

The louver 5 can be provided with a mechanism capable of independently controlling the opening and closing of each door. As an example of this mechanism, there is a mechanism that allows the projector to select an open / close mode (forced discharge mode) of the open / close door on an on-screen menu screen. If the user selects it, a state similar to the forced air cooling after the power is turned off is executed, and the forced discharge of dust is performed. In this case, unless the user presses the power-off (OFF) key, the operation is performed so that this state is continued. This is an effective means when there is a limitation on the forced air cooling time after the power is turned off, and in this time, dust cannot be blown out.

In FIG. 1B, a louver 5 is used as opening / closing means.
Was used, but a slide could be used instead. In FIG. 1B, the louver and the fan are provided below the cross dichroic prism 1 and each liquid crystal panel. However, the louver and the fan can be provided above the cross dichroic prism 1 and each liquid crystal panel. .

Next, the operation of the embodiment of the liquid crystal projector of the present invention will be described with reference to FIG.

The air flow indicated by the arrow in FIG. 2A is for air cooling when the projector is operating. The outside air passes through the filter 7 by the fan 2 and passes through the partition plate 6.
Is drawn inside the box. At this time, the louvers 5 are all open and the air taken in by the fan 2 is
After passing through the louver 5, the cross dichroic prism 1 and the liquid crystal panels 3a, 3b, 3c are cooled and exit to the exhaust duct.

Next, when the power source of the light source is turned off, FIG.
The other doors are closed while the door 5b of the louver 5 is open. At this time, all the air taken in by the fan 2 concentrates on the open / close door 5b of the louver 5, and the air volume increases. As a result, dust entering the gap of the liquid crystal panel 3b is eliminated and discharged to an exhaust duct (not shown).

Further, as shown in FIG.
Only the open / close door 5a of the louver 5 near a is opened, all other open / close doors are closed, and dust entering the gap of the liquid crystal panel 3a is eliminated and discharged to the exhaust duct. Finally, dust is removed from the third liquid crystal panel 3c in the same manner. These operations are performed during the forced air cooling period after the power is turned off.

Further, by controlling the power supply voltage applied to the fan 2, increasing the fan voltage after the power is turned off, and increasing the rotation speed of the fan 2, a larger air volume can be obtained.

In FIG. 2, the opening and closing doors are opened in order and the air is blown to each liquid crystal panel in order, but as shown in FIG.
May be closed, and all of the doors 5a, 5b, 5c may be opened and air may be sent to each liquid crystal panel at one time to remove dust in the gaps between the liquid crystal panels. In this case, the air volume of the fan 2 is increased.

If all the open / close doors are closed at the end of the forced air cooling time, the intrusion of dust into the housing can be reduced.

[0032]

As described above, in the liquid crystal projector according to the present invention, the following effects can be obtained by providing the opening / closing means for controlling the position of the cooling air blown to the liquid crystal panel section downstream of the cooling fan. (1) By using the forced air cooling period after turning off the power of the light source of the projector, the amount of air blown to the liquid crystal panel can be automatically increased, and dust can be efficiently forcibly discharged from the surface of the liquid crystal panel. Performance degradation due to dust can be prevented. (2) Since the air volume inside the set is increased after the power of the projector is turned off, the problem of noise caused by the fan during normal operation can be avoided.

[Brief description of the drawings]

FIGS. 1A and 1B are views of main parts showing an embodiment of a liquid crystal projector of the present invention, wherein FIG. 1A is a plan sectional view of an optical unit 20, FIG. 1B is a longitudinal sectional view of a liquid crystal panel, and FIG. FIG. 3 is a perspective view of a louver portion.

FIG. 2 is a vertical cross-sectional view of a liquid crystal panel unit for explaining an operation of the liquid crystal projector according to the embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a liquid crystal panel unit for describing an operation of the liquid crystal projector according to the embodiment of the present invention.

4A and 4B are schematic diagrams showing a configuration of an optical unit 50 of a conventional liquid crystal projector, wherein FIG. 4A is a plan sectional view, and FIG. 4B is a longitudinal sectional view of a liquid crystal panel.

[Explanation of symbols]

1,51 Cross dichroic prism 2,60 Fan 3a, 3b, 3c, 57a, 57b, 57c Liquid crystal panel 5 Louver 6,58 Partition plate 7,61 Filter 8a, 8b, 9a, 9b, 9c Mirror 10,53 Light source 11, 56 Projection lens 12, 55 Housing 13, 54 Polarization conversion element 14, 52 Lens array 59 Rectifier fin 62a, 62b, 63a, 63b, 63c Mirror

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 33/12 G03B 33/12 G09F 9/00 302 G09F 9/00 302 F term (Reference) 2H088 EA68 HA13 HA21 HA24 HA28 MA20 2H091 FA05X FA14Z FA26X FA41Z LA30 5G435 AA11 AA12 BB12 BB17 DD04 GG44

Claims (7)

[Claims] 1. A means for separating light emitted from a light source into three primary colors, three liquid crystal panels provided at required positions on an optical axis of each light, and for transmitting the separated light, A cross dichroic prism for synthesizing each of the lights transmitted through the liquid crystal panel, and a projection lens for enlarging the synthesized light and projecting it on a screen, wherein the three liquid crystal panels are formed of the cross dichroic prism. The cross dichroic prism is disposed inside a box that is open up and down opposite to the three side faces, and is sent into the box by a cooling fan below or above the cross dichroic prism and each of the liquid crystal panels. Opening / closing means for controlling the position of blowing the incoming cooling air to the cross dichroic prism and each of the liquid crystal panels is arranged to close the box. A liquid crystal projector characterized by being used. 2. The opening / closing means includes four openable / closable doors for blowing out the cooling air corresponding to the cross dichroic prism and each of the liquid crystal panels, and the four doors are independently opened / closed. The liquid crystal projector according to claim 1, wherein the liquid crystal projector can be used. 3. The liquid crystal projector according to claim 2, wherein the opening / closing means includes a door opening / closing control mechanism for blowing the cooling air to each of the liquid crystal panels in order. 4. The apparatus according to claim 2, wherein the opening / closing means includes a control mechanism for closing all the doors after the power of the light source is turned off and the cooling fan is operated for a predetermined time. Or the liquid crystal projector according to 3. 5. The liquid crystal projector according to claim 1, wherein a louver or a slide is used as the opening / closing means. 6. The liquid crystal projector according to claim 1, wherein the cooling fan includes a rotation speed control mechanism. 7. The liquid crystal projector according to claim 1, further comprising an operation unit capable of selecting an operation of the opening / closing unit on an on-screen menu screen.