JPH09185028A - Air cooling structure of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently guide the flow of a cooling fan because of a large rise in the temperature of a liquid crystal display part and further suppress the temperature on the whole by providing a blocking member which closes part of the cooling air intake of a ventilation path at the cooling air intake. SOLUTION: The ventilation part 40 is constituted between an incidence-side polarizing plate 2 and a liquid crystal 1, and the liquid crystal panel 1 and a projection-side polarizing plate 3. Then blocking members of heights H1 and H2 in, for example, a wall shape are provided above and below the cooling air intake 31 of the ventilation part 40. The lower part of the intake for cooling air is closed, so the capacity of passing air decreases and the flow faces down on the whole. Then the air is warmed and strikes on the lower end of the liquid crystal display part 30, so the air changes its direction upward and flows out of the upper part of the liquid crystal display part 30. Consequently, air having passed above an intake part where the heating value is relatively small passes through the center part where the heating value is large and flows out of the upper part of the liquid crystal display part 30 where the heating value is small, so the rise in temperature becomes uniform on the whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cooling structure for a projection type liquid crystal display device which employs forced air cooling for guiding cooling air to a liquid crystal display section by using a cooling fan.

[0002]

2. Description of the Related Art Generally, a projection type liquid crystal display device has a structure as shown in FIG. 19 when viewed from the top of the liquid crystal display device, and the light emitted from a light source lamp 13 is a reflecting mirror 13a which is a concave mirror. The emitted light is reflected and emitted by the UV-IR (ultraviolet-infrared) filter 10 and the dimple shape lens 9, and then the incident side polarization plate 2, the liquid crystal panel 1 (liquid crystal module) and the emission polarization plate. The image of the liquid crystal panel 1 is projected on the screen (not shown) through the liquid crystal display unit composed of 3 and further through the Fresnel lens 8 and the projection lens 12.

At this time, the polarizing plates 2 and 3 and the liquid crystal panel 1 partially block the light and generate heat. Therefore, in the liquid crystal display section, the incident side polarizing plate 2, the emitting side polarizing plate 3 and the liquid crystal panel 1 are arranged. Must be cooled so that it does not exceed its heat resistant temperature. Further, cooling of the Fresnel lens 8, the dimple shape lens 9, the UV-IR filter 10, etc. may be required. This is to prevent the phenomenon that the liquid crystal panel 1 and the respective polarizing plates 2 and 3 may deteriorate in display performance when the temperature exceeds the heat-resistant temperature and the life may be shortened.

In recent years, however, the light source has been improved in order to make the image on the liquid crystal display device brighter, and the intensity of the light entering the liquid crystal display section tends to gradually increase. It's getting harder to stay below. In order to deal with this, various measures are currently taken to suppress the liquid crystal display unit to a temperature lower than the heat resistant temperature. Further, if the temperature of the whole is uniform, it is possible to suppress thermal deformation of the liquid crystal panel and the polarizing plate, and
The projected image quality is improved.

In the first example of the cooling technique for the liquid crystal display section, as shown in FIG. 19, air outside the liquid crystal display device is introduced into the ventilation section 4 by using the cooling fan 11, and the liquid crystal display section is cooled. There is a forced air cooling method in which the liquid crystal display unit is cooled by directly applying air to it, which is the most common method. Although the cooling fan 11 is arranged on the right side surface of the liquid crystal display device as viewed from the light source lamp 13 in FIG. 19, it may be arranged on the left side surface, the lower surface, or the upper surface.

Further, in order to improve the capability in the forced air cooling system, a transparent air guide plate which is provided in parallel with the liquid crystal panel at a predetermined distance in parallel with the liquid crystal panel is used, and the efficiency is improved between the polarizing plate and the liquid crystal panel. Example of a projection type liquid crystal display device that tries to blow cooling air (see Japanese Patent Laid-Open No. 4-309940)
Can be seen. In the forced air cooling method, a cooling duct with a built-in liquid crystal display is built in to prevent dust from entering, and a cooling fan circulates the air inside the cooling duct to dissipate the heat inside the cooling duct through the duct. It is also possible to use a fin so that the fins are discharged to the outside.

The second example of the cooling technique is to improve the cooling performance by a method of previously cooling the air sucked into the cooling fan by using a Peltier element, and further intrusion of dust into the liquid crystal display section. In order to prevent this, a method has been devised in which cooling air is circulated in a cooling duct containing a liquid crystal display unit and the internal air is cooled by a Peltier element (see Japanese Utility Model Laid-Open No. 6-2337).

The liquid crystal display portion of the liquid crystal display device shown in FIG. 19 is, as shown in detail in FIG. 20, an incident side polarization plate 2, a liquid crystal panel 1, an emission side polarization plate 3, and a Fresnel not shown. It is fixed by a holding portion 5 having a supporting member for fixing the position of an optical component such as a lens. Further, the holding part 5 has a structure which is completely closed except for the ventilation part 4 so that light from the light source does not leak to the outside. The liquid crystal panel 1 is provided with a holding portion 5 so that signals can be input from the outside.
Part of it is jumping out.

The position of the cooling fan (not shown in FIG. 20) may be on the front side or the back side of the paper surface of FIG. 20, but the following description will be made assuming that the cooling fan is on the front side in FIG. . The ventilation part 4 is formed by notching and opening a part of the holding part 5 located between the incident side polarization plate 2 and the emission side polarization plate 3 as shown in FIG. 1 is installed in such a manner as to partition the opening, and is designed to cool both surfaces of the liquid crystal panel 1 and one surface of the incident side polarization plate 2 and the emission side polarization plate 3 by cooling air flowing through the ventilation part 4. There is. At this time, the opening 4a on the front side of the drawing is the inflow portion of the cooling air, and the rear side is also the same opening 4b, which is the outflow portion through which the cooling air flows out. In addition to the above, as shown in FIG.
When the ventilation part 4 is configured so that cooling air flows between the dimple shape lens 9 and the Fresnel lens 8 and both surfaces of the incident side polarization plate 2, the liquid crystal panel 1, and the emission side polarization plate 3 are cooled. There is also.

The setting of the ventilation amount in the ventilation unit 4 is as follows. That is, in general, the amount of heat generated by the incident side polarizing plate is the largest, and when the amount of heat generated by the liquid crystal panel is 1, the incident side polarizing plate generates about 1.6 and the emitting side polarizing plate generates about 0.
6. Further, the heat resistant temperature of the liquid crystal panel is generally lower than that of the polarizing plate. Therefore, the distance between the incident side polarizing plate and the liquid crystal panel and the configuration of the ventilation part are determined so that the cooling air flows most between the incident side polarizing plate and the liquid crystal panel.
Depending on the relationship between the heat resistant temperature and the heat generation amount, it may be necessary to flow cooling air to the light source side of the incident side polarizing plate and the projection side of the emitting side polarizing plate.

[0011]

In the liquid crystal display part, the heat generation density varies depending on the characteristics of the light source lamp, the central part generates a large amount of heat, the peripheral part has a small amount, and the four corners of the liquid crystal display part are the smallest. Therefore, if no cooling means is taken, the temperature tends to rise in the central part.

As described above, the liquid crystal display device generally employs a so-called air-cooling system in which cooling air is introduced into the liquid crystal display section by a fan to suppress the temperature of the liquid crystal panel. In this type of air cooling system, it is necessary to increase the flow velocity of the cooling air at the position where the temperature rise is large as much as possible to suppress the temperature rise and to make the entire temperature uniform.

However, increasing the size of the cooling fan causes an increase in the size and cost of the liquid crystal display device, which is difficult to implement. Therefore, in consideration of the flow velocity distribution of the cooling fan, the cooling fan is arranged at a position where the temperature rise of the liquid crystal display part is large at the place where the flow velocity of the cooling fan is high. Requires a cooling fan to be installed at an optimum position with respect to the liquid crystal display unit, which is a major structural limitation.

Further, the temperature rise of the air passing through the central portion of the liquid crystal panel and the incident side polarization plate where the heat generation density is large is large,
Since the temperature difference between the liquid crystal panel and the polarizing plate and the cooling air becomes smaller, the cooling effect decreases, and the temperature of the liquid crystal panel and the polarizing plate tends to rise at the cooling air outflow part. There is a problem that it cannot be cooled.

The present invention has been made in view of the above circumstances, and it is possible to efficiently guide the flow of the cooling fan to a place where the temperature rise of the liquid crystal display portion is large and further suppress the overall temperature. An object of the present invention is to provide a projection type liquid crystal display device that can be used.

[0016]

The present invention has the following arrangement to solve the above-mentioned problems. The invention according to claim 1 has a liquid crystal display unit including a liquid crystal panel on which an image to be projected is displayed, and a light source for projecting light to the display unit, and an image is projected on an external projection surface by light transmitted through the display unit. In a projection type liquid crystal display device for projecting onto a liquid crystal display device, an air passage for passing cooling air is provided in the liquid crystal display unit, and a cooling air inlet of the air passage is provided with a closing member that partially closes the cooling air inlet. This is an air-cooling structure for a liquid crystal display device, characterized in that a path is changed so that cooling air is intensively guided to a target place requiring cooling.

According to a second aspect of the present invention, the liquid crystal display unit includes a liquid crystal panel and a polarizing plate, and the closing member guides the cooling air toward the central portions of the liquid crystal panel and the polarizing plate. The air-cooled structure of the liquid crystal display device according to claim 1, wherein

The invention of claim 3 is the air-cooling structure for the liquid crystal display device according to claim 1 or 2, wherein the closing member closes 0 to 40% of the cooling air inlet.

According to a fourth aspect of the invention, the closing member is formed at the cooling air inflow port so as to project from the end portion along the width direction of the liquid crystal panel toward the central portion, and the liquid crystal panel and the incident side polarization plate. The first blocking member of the ventilation part between the two sides and the second blocking member of the ventilation part between the liquid crystal panel and the emission side polarizing plate are different in protrusion height from each other. An air-cooling structure for a liquid crystal display device according to any one of claims 1 to 3.

The invention according to claim 5 is characterized in that a cooling air passage for guiding cooling air to the inlet is integrally formed with a holding portion surrounding and holding the liquid crystal display portion in the plane direction. It is an air-cooled structure of the described liquid crystal display device.

Therefore, according to the first aspect of the present invention, a ventilation passage for passing cooling air is provided in the liquid crystal display portion, and a closing member for closing a part thereof is provided at the cooling air inlet of the ventilation passage. Since the cooling air path is changed so that the cooling air is concentratedly guided to the target location where cooling is required, the location where the temperature of the liquid crystal display unit becomes high regardless of the position of the cooling fan (for example, the claim The cooling air can be guided to the central part of the liquid crystal panel and the polarizing plate in 2) to suppress the temperature rise there, and also to keep the temperature of the entire liquid crystal display element low. Further, according to the invention of claim 3, since the closing member closes 0 to 40% of the cooling air inflow port, the cooling air can be surely concentrated and guided to the place where the temperature of the liquid crystal display part becomes high. You can Therefore, the temperature rise can be surely suppressed.

Further, according to the invention of claim 4, the closing member is formed at the cooling air inflow port so as to project from the end portion along the width direction of the liquid crystal panel toward the central portion. Since the first blocking member of the ventilation part between the incident side polarization plate side and the second blocking member of the ventilation part between the liquid crystal panel and the emission side polarization plate have different protrusion heights, It is possible to make the cooling air volumes different between the incident side polarization plate side and the emission side polarization plate side of the liquid crystal panel. Therefore, the heat generation of the liquid crystal panel, the incident side polarization plate, and the emission side polarization plate can be optimally cooled according to the conditions.

Further, according to the invention of claim 5, the cooling duct for guiding the cooling wind to the inlet is formed integrally with the holding part which surrounds and holds the liquid crystal display part from the plane direction thereof, so that the cooling duct is formed. The degree of freedom of installation when connecting is high. That is, when the cooling duct and the cooling fan are directly connected to the inlet, for example, when the inlet is located below the liquid crystal display unit, the installation of the cooling duct and the cooling fan is restricted, and the inlet is located below. It may not be possible to provide it. On the other hand, according to the invention of claim 5, the cooling air duct may be connected to the opening of the cooling air passage at a position different from the inlet, so that the cooling air can flow regardless of the arrangement of the cooling fan. It can be introduced from the inlet.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. In addition, in FIG.
The same parts as those in FIG. 20 are designated by the same reference numerals.

1 and 2 show examples of the liquid crystal display unit 30 provided in the ventilation part of the projection type liquid crystal display device according to the embodiment of the present invention, and FIG. 3 shows the projection type (projection type) liquid crystal display device. FIG. 4 shows an overall side view (corresponding to claims 1 to 4) and FIG. 4 shows the same front view.

In the liquid crystal display device of the present invention, the liquid crystal panel 1 in the liquid crystal display section 30, the polarizing plate (the incident side polarizing plate 2 and / or the outgoing side polarizing plate 3), and other optical components which need cooling are cooled. The ventilation part is configured to allow air to flow (corresponding to claim 2), and a duct for guiding the air from the cooling fan 11 to the ventilation part or an alternative thereto is provided.

Here, only the liquid crystal panel 1 and the polarizing plates (the incident side polarizing plate 2 and / or the emitting side polarizing plate 3) need to be cooled, and like the case of FIG. 20, the liquid crystal panel 1 and the incident side polarizing plate 2 are required.
Between the liquid crystal panel 1 and the exit side polarizing plate 3, the ventilation part 40
It will be explained as if there is.

Taking the size of each part as an example, the size of the liquid crystal of the liquid crystal display part 30 is 3.6 inches (55 mm × 73).
mm) can be used, and there is a gap of 4 mm between the incident side polarization plate 2 and the liquid crystal panel 1 and a 3 mm gap between the liquid crystal panel 1 and the emission side polarization plate 3, and the dimensions in the height direction are both 55 mm
And constitutes the ventilation part 40. At this time, the light source lamp 13 is placed on the right side in both FIG. 1 and FIG. Although the present invention is not limited to such a size, it is preferable that the closing member is 0 to 4 of the total area of the cooling air inlet.
It is possible to close 0% (corresponding to claim 3).

Further, as shown in FIGS. 3 and 4, in the liquid crystal display device, in order to prevent dust from entering the liquid crystal display section 30, a ventilation section 40 closed from the cooling air inlet 31 of the liquid crystal display section 30. It has a closed structure in which the cooling air that has entered and that has come out of the cooling air outlet 32 is cooled in the sealed duct 19 and then made to flow again from the cooling air inlet 31.

That is, the duct 19 is a hollow air passage provided in a U-shape that opens downward from both side wall portions of the liquid crystal display unit 30 to the upper portion of the display unit 30,
One end is connected to the cooling air flow inlet 31 and the other end is connected to the cooling air flow outlet 32, and the heat absorbing fin 20 for absorbing heat of the cooling air is provided in the upper portion of the liquid crystal display unit 30 and the heat absorbing fin 20 is integrally provided outside the upper portion. The heat dissipating fins 21 are provided. A cooling fan 11 that circulates cooling air is provided in the duct 19. In addition, the radiation fin 2
A fan (not shown) blows cooling air onto 1 to cool it.

Incidentally, as shown in FIGS. 7 and 10 which will be described later, the liquid crystal panel 1 is supported and fixed by fitting the upper portion thereof into a groove-shaped holding groove 5a which is recessed in the upper portion of the holding portion 5, and the lower portion thereof. It is supported and fixed by a supporting member 17 fixed to the lower part of the holding portion 5. Further, the liquid crystal panel 1 has a liquid crystal portion 16 through which projection light passes, almost in the center thereof.

In such a structure, the cooling air passes through the sealed ventilation section 40 between the incident-side polarization plate 2 and the emission-side polarization plate 3, and is discharged from the liquid crystal panel 1 and the respective polarization plates 2 and 3. The heat is absorbed, and the cooling air passes through the duct 19 and the heat absorbing fins 20 placed in the duct 19 above the liquid crystal display unit 30 to give the absorbed heat to the heat absorbing fins 20. The heat absorbing fin 20 is a duct 19 integrated with the heat absorbing fin 20.
Heat is applied to the radiating fins 21 placed outside, and the radiating fins 21 are cooled by cooling air by a fan (not shown) placed outside the duct 19.

As described above, the temperature of the cooling air that has given heat to the heat-absorbing fins 20 drops, passes through the duct 19 and the ventilation section 4
Returning to 0, the liquid crystal display unit 30 is cooled. In addition, the duct 19
A cooling fan 11 is built in together with the heat absorbing fins 20, and the cooling fan 11 circulates the cooling air clockwise in FIG.

For comparison, in the liquid crystal display section having the ventilation section 4 of FIG. 20, the duct 1 shown in FIGS. 3 and 4 is used.
Consider a structure (comparative example) in which a duct similar to that of No. 9 is provided to circulate cooling air. In the case of the comparative example, the temperature difference between the surface temperature of each of the liquid crystal panel 1 and the incident side polarization plate 2 and the ambient temperature, that is, the temperature rise has distributions as shown in FIGS. 5 and 6, respectively. In FIG. 5 and FIG. 6, the cooling air from the cooling fan 11 flows in from the right side and flows out to the left side. A distribution with a low temperature rise is obtained. In the liquid crystal panel 1, the average temperature difference is 13.8 ° C. and the maximum temperature difference is 16.1 ° C., and in the incident side polarizing plate 2, the average temperature difference is 24.9 ° C. and the maximum temperature difference is 33. 6 ° C.

FIG. 7 shows the flow of cooling air inside the liquid crystal display section in the comparative example. In FIG. 7, the cooling air that has flowed in from the cooling air inlet 4a on the right side flows to the left substantially in parallel, and the temperature rises while passing through the ventilation part 4 in contact with the liquid crystal panel 1. Therefore, the liquid crystal panel 1 and the incident side polarization plate 2
As shown in FIGS. 5 and 6, the temperature rises from the right side to the left side. In particular, since the temperature of the flow passing through the central portion where the heat generation amount is large greatly increases, the temperature on the left side, that is, the outlet side of the cooling air outlet 4b is high.

1 and 2 are enlarged views of the structure of the ventilation part 40 of the present invention. As shown in FIGS. 1 and 2, the incident side polarization plate 2, the liquid crystal panel 1, and the liquid crystal panel 1
A ventilation part 40 is formed between the output side polarizing plate 3.
Further, for example, a wall-shaped closing member having a height H1 is provided above and below the cooling air inlet 31 of the ventilation portion 40 from the lower surface position of the ventilation portion 40 in the vertical direction, and the upper surface position of the ventilation portion 40 is provided. From above, a wall-shaped closing member is provided at a height H2 above the upper surface in the vertical direction, and the cooling air inlet 31 is partially closed by these closing members,
The opening area of the inflow port 31 is smaller than the opening area of the duct 19.

As shown in FIG. 1, the construction and attachment method of the closing member are such that the height H1, which has adhesiveness, is
The tape 6 having a width corresponding to H2 may be appropriately attached to the holding portion 5 so as to face the upper and lower portions of the cooling air inlet 31, and the tape 6 may be integrally wall-formed in advance with the holding portion 5 as shown in FIG. The ribs 7 may be formed. Further, although not shown, a rib may be integrally formed on the duct 19 side to close the ventilation part. 1 and 2, the upper part and the lower part are shown closed, but in the present invention, only the upper part or only the lower part may be closed. The blocking height (blocking area or blocking rate) is determined by the capacity of the cooling fan, heat generation conditions, temperature conditions, and the like.

FIG. 8 shows the surface temperature and the ambient temperature of the upper portion, the central portion and the lower portion of the liquid crystal panel 1 near the cooling air outlet (cooling air outlet 32) of the ventilation portion 40 when only the lower portion of the ventilation portion 40 is closed. It is the figure which plotted the temperature difference of, ie, the temperature rise. Further, FIG. 9 also plots the temperature rises of the upper part, the central part, and the lower part of the incident side polarization plate 2 near the cooling air outlet 32. Further, FIG. 10 shows the flow of the cooling air in the liquid crystal display unit 40 in the above case.

Regarding the incident side polarizing plate 2, referring to FIG. 9, the temperature at the central portion of the polarizing plate 2 is the highest among the three points until the closing height is 20 mm, but the temperature gradually decreases. There is a tendency. On the contrary, the lower part of the polarizing plate 2 tends to have a higher temperature difference as it is closed. This is because the amount of cooling air passing through the lower part of the ventilation part 40 is reduced by closing from the lower part, and the amount of air passing through the central part is increased by that amount, and the temperature of the central part can be suppressed. Thus, in this embodiment, preferably, the incident side polarizing plate 2 is formed with the closing member so as to be closed at a height of 20 mm, so that the entire surface temperature can be minimized.

Regarding the liquid crystal panel 1, referring to FIG. 8, the temperature change in the central portion is small and the temperature in the lower portion is 10
Starting to increase from mm. Therefore, the closing member is
It is desirable to close up to a height of 0 mm to 20 mm because the temperature can be suppressed most.

FIG. 10 shows the flow of the cooling air inside the liquid crystal display unit 30 at this time, and since the lower part of the cooling air inlet (around the cooling air inlet 31) is closed, FIG. Compared with the comparative example, the amount of airflow passing through the lower part of the inflow part is reduced, and the overall flow is downward in the inflow part. The downward flow changes its direction due to an increase in buoyancy due to warming of air and a collision with the lower end of the liquid crystal display unit 30, so the downward flow changes its direction upward and flows out from the upper part of the liquid crystal display unit 30. Therefore, the air that has passed through the upper part of the inflow part (see FIG. 5 and FIG. 6) where the heat generation amount is relatively small passes through the central part where the heat generation amount is large, and flows out from the upper part of the liquid crystal display part 30 where the heat generation amount is small. Therefore, the temperature rise becomes uniform throughout.

In the above description, the closing member was closed from the lower part, but it is clear that the same effect can be obtained when the closing member is provided from the upper part, and the upper and lower parts are closed. It is obvious that the effects of the present invention can sometimes be obtained. For example, due to the characteristics of the light source lamp 13,
When the lower part of the liquid crystal display unit 30 generates a large amount of heat, it is desirable to allow a large amount of cooling air to flow to the lower part, and when the upper part has a large amount of heat generation, it is desirable that a large amount of cooling air flows to the lower part, and a large amount of the upper part heat is generated. When there is a lot of water, it is desirable to allow more water to flow to the upper part. As described above, how to close the closing member is determined by the state of heat generation distribution and the state of inflowing air.

Further, in the above, the incident side polarization plate 2,
The explanation has been made on the assumption that only the exit side polarizing plate 3 and the liquid crystal panel 1 need to be cooled, but other optical parts, for example,
Fresnel lens, dimple shape lens, UV-
The same applies to the case where the IR filter or the like needs to be cooled and the ventilation section 40 is also formed therein, and the effect of the present invention can be obtained by closing the upper section, the lower section, or both of the respective ventilation sections 40. Can be further obtained.

The first embodiment described above can be applied to the liquid crystal display device shown in the first and second conventional examples as appropriate to obtain the same cooling effect.

Here, as shown in FIG. 11, the closing heights H1 and H1 'and H2' and H2 'on the incident side polarization plate 2 side and the emission side polarization plate 3 side of the liquid crystal panel 1 of the ventilation part 40 may be changed. It is possible (corresponding to claim 4). As is clear from FIGS. 5 and 6, it has been found that the liquid crystal panel 1 is less likely to obtain the effect of closing the ventilation part 4 from the lower side than the incident side polarization plate 2. Further, the incident side polarizing plate 2 is significantly affected by the flow of cooling air on the incident side polarizing plate 2 side of the ventilation part 40, but at the same time, the liquid crystal panel 1 flows on the emitting side polarizing plate 3 side by the cooling air. Is also affected by.

Therefore, if the ventilation part 40 on the exit side polarizing plate 3 side is not closed, under the same conditions as in FIG. 5 and FIG.
The highest temperature is 33 ° C. in the incident side polarizing plate 2 and 16 ° C. in the liquid crystal panel 1, and it is possible to obtain the same cooling performance as when the closing member is closed even if the height of the closing member is changed. Do you get it.

In this way, the incident side polarization plate 2 of the ventilation part 40 is
It is desirable to change the closing height between the light-emitting side and the output-side polarizing plate 3 side. As shown here, when the output-side polarizing plate 3 side is not closed (that is, when the closing member is not provided), a closing member is installed. This will reduce costs.

12 and 13, at the cooling inlet 31, the closing member (shown by tape 6) on the incident side polarizing plate 2 side is 20 mm (H2) from the lower side, and the closing member on the emitting side polarizing plate 3 side is the upper side. It is a plot of the temperature rises of the liquid crystal panel 1 and the incident side polarizing plate 2 when the closing amount (H1) from the upper side on the incident side polarizing plate 2 side is changed in the state of being closed by 10 mm from (H1 ′). As can be seen from FIGS. 12 and 13, the liquid crystal panel 1 and the incident side polarization plate 2 also have the lowest temperature in the range of 0 to 10 mm. Thus, in the ventilation part 40, the upper part of each of the incident side polarizing plate 2 side and the emitting side polarizing plate 3 side,
It is effective to control the temperature by changing the closing height of the lower part.

As described above, by closing the upper part and the lower part of the cooling air inlet 31 of the ventilation part 40 at the heights of H1 and H2, respectively, more cooling air is guided to the central part where the heat generation is large, and the temperature is increased. The rise can be suppressed.
FIG. 14 shows an image of this cooling air flow (indicated by reference numeral 14). Flow 14 flowing into the ventilation part 40 from the right side
The flow is bent by the closing member of the cooling air inlet 31, for example, the tape 6 or the rib 7, toward the center of the liquid crystal panel 1, and the temperature of the cooling air gradually rises as it flows toward the cooling air outlet 32. Therefore, it flows out while rising due to the influence of buoyancy. By this action, the cooling air flow 1 is concentrated on the central portion of the liquid crystal panel 1.
4 is collected, and is made to flow out from a corner portion (upper left portion) which generates less heat. Therefore, the result is different from using a cooling fan having the same opening size as the cooling air inlet 31. That is, if the cooling fan having the same opening size is used, the parallel flow 1 shown in FIG.
This is because, even when the liquid crystal panel 1 passes through the central portion of the liquid crystal panel 4, the flow 14 does not bend downward and is not collected in the central portion.

In the first embodiment, the cooling duct 1
Although the case where the cooling method using 9 is adopted has been described, the same applies to the case where cooling air is introduced from the side surface of the liquid crystal display unit 30 without using a cooling duct. In this case, when there is a guider (not shown) such as a baffle plate in the inflow part of the ventilation part 40, the guider may have a structure of a closing member that partially closes the ventilation part.

In the above description, the cooling air flows in from the right side of the liquid crystal display unit 30 and flows out to the left side, but the present invention is not limited to this, and the upper or lower side of the liquid crystal display unit 30 is not limited to this. The present invention can be applied to the case where the cooling air is introduced from the inside. In this case, since the liquid crystal panel and the polarizing plate are generally horizontally long due to the screen size, the air flow path length can be shortened, the temperature rise of the cooling air can be suppressed, and the liquid crystal The temperature of the display unit 30 can be suppressed.

For example, when the cooling fan 11 is located below the liquid crystal display unit 30 of the liquid crystal display device, the configuration as shown in FIG. 15 can be adopted. In the configuration of FIG. 15, the cooling fan 11 is arranged facing the long side of the lower portion of the horizontally long liquid crystal panel 1 and is directed upward, and the cooling air inlet 31 of the liquid crystal display unit 30 is provided at the lower portion of the liquid crystal panel 1. Wall-shaped closing members 6 and 7 are extended from both ends toward the center along the long sides to partially close the flow 14 of the cooling air. According to the configuration of FIG. 15, as compared with FIG.
It is obvious that the flow path length of the cooling air flow 14 within 0 is short, and the cooling air of low temperature which does not absorb heat can be swiftly flowed, and the cooling effect can be further obtained. it can.

Next, a second embodiment according to claim 5 will be described. The first embodiment has shown the case where the cooling air flows into the ventilation part from one side surface of the liquid crystal display device and further flows out from the other side surface, or the cooling air flows into the ventilation part from below and further flows out from above. , FIG. 10, FIG.
As shown in FIG. 4, in the liquid crystal display unit 30, the flow passing through the central portion with a large amount of heat generation passes through the upper portion with a small amount of heat generation, so that the overall temperature rise is suppressed.

Therefore, in the second embodiment, as shown in FIG. 16 (perspective view of main part) and FIG. 17 (cross-sectional view perpendicular to the optical axis), the ventilation part 40 is cooled by cooling air from one side surface and the bottom surface of the liquid crystal display part. It is designed to flow in and flow out from the other side surface and upper surface. With this, the cooling performance can be further improved.

Therefore, in the second embodiment, as shown in FIGS. 16 and 17, the air flow paths 18 (18a and 18b) are formed in the upper and lower portions of the liquid crystal display portion 30 of the holding portion 5. Each of the air flow paths 18a and 18b is in the shape of a hollow box having a rectangular cross section, and its longitudinal direction is along and adjacent to the upper side and the lower side of the horizontally long liquid crystal panel 1, and the liquid crystal panel 1 side has an open portion 18a ₁ and 18 b ₁ is formed integrally with the holding groove 5 a forming portion of the holding portion 5.

Then, in FIG. 17, the upper air passage 1
8a is located substantially from the center of the liquid crystal panel 1 in the lateral direction to the left end (corresponding to the end surface of the holding portion), and the outlet for cooling air (corresponding to the cooling air outlet 32) is located on the left side. The opening 18a _{2 is formed} in the direction. Further, the lower air flow path 18b is
The liquid crystal panel 1 is located from the center in the lateral direction to the right end, and a cooling air inlet (corresponding to the cooling air inlet 32) is an opening 18b ₂ facing the right direction.

Therefore, as shown in FIG. 17, the cooling air flow 14 from the cooling fan (not shown) arranged laterally of the liquid crystal display device is supplied to the lower air passage 18b provided in the holding portion 5. Since it flows in from the opening 18b ₂ and goes upward from the open portion 18b _{1 of the} air flow path 18b, it is guided to the lower part of the liquid crystal display unit 30 by the lower air flow path 18b. The cooling air that has flown in this way flows upward toward the liquid crystal panel 1 of the liquid crystal display unit 30 and the respective polarizing plates 2 and 3 to cool it, and then the holding unit 5
It flows into the open portion 18a ₁ of the upper air flow path 18a and flows out from the opening 18a ₂ . By doing so, cooling air can be made to flow into the liquid crystal display unit 30 from below regardless of the arrangement of the cooling fan 11.

In the above case, the inflow of the cooling air is in the lower part. However, since the cooling air takes the heat of the liquid crystal display unit 30 and the temperature rises, the cooling air inflows from the lower part and the upper part. This is because it is more effective to spill into the.
However, structurally, if it is better to let the cooling air flow into the liquid crystal display unit 30 from the upper portion, it may flow from the upper portion and flow out to the lower portion.

A modification of the second embodiment is shown in FIG. In the configuration of the second embodiment, as shown in FIG. 17, the flow of the cooling air 1 in the upper right and lower left regions of the liquid crystal display unit 30 is reduced.
4 may not be fully reached. In the case where the temperature rise in these regions becomes a problem, for example, when the temperature rise in the upper right region of the liquid crystal display unit 30 becomes a problem, as in the modification of FIG. 18, the same as in the second embodiment. In addition to providing the air flow paths 18a and 18b, a cooling member shown in the first embodiment is provided on the side surface of the liquid crystal display portion 30 with a closing member (tape 6 or rib 7) at the cooling air inlet 31 as in the case of FIG. It is desirable to adopt.

When the configuration of this modified example is adopted, FIG.
As shown in FIG.
It is possible to suppress the temperature rise in this region by flowing in the upper right part of 0. As for the lower left area, the temperature rise can be suppressed by providing a cooling air outlet (shown by a broken line 32) on the left side surface of the liquid crystal display section 30.

The air passage 18 provided in the holding portion 5
a and 18b and the size of the cooling air inflow port (cooling air inflow port 31) and the outlet (cooling air outflow port 32) provided on the side surface of the liquid crystal display unit 30, the heat generation amount of the liquid crystal display unit 30, the capacity of the cooling fan 11, etc. It is decided in consideration of.

[0062]

As is apparent from the above description, in the projection type liquid crystal display device of the present invention, at least a part of the cooling air inflow part of the liquid crystal display part is closed, so that the cooling air is supplied to the central part where a large amount of heat is generated. It is possible to effectively induce, suppress the temperature rise of the polarizing plate and the liquid crystal display portion of the liquid crystal panel, and make the entire temperature uniform.

According to the first aspect of the present invention, the temperature rise of the polarizing plate and the liquid crystal panel can be suppressed by a simple means with a blocking member such as an adhesive tape or a rib.

According to the second aspect of the invention, the cooling air can be guided to the central portion where a large amount of heat is generated, and the cooling can be performed intensively.

According to the third aspect of the invention, by closing 0 to 40% of the cooling air inlet, sufficient cooling can be performed without reducing the amount of cooling air.

According to the invention of claim 4, it is possible to prevent the temperature rise of the liquid crystal panel while suppressing the temperature rise of the central portion of the incident side polarization plate.

According to the fifth aspect of the present invention, the cooling air passage is integrally formed with the holding portion of the liquid crystal display portion, so that the assembling process is simplified, the flow length of the cooling air can be shortened, and the temperature rises. Can be further suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view of an essential part of an example of a liquid crystal display unit provided with a ventilation part according to an embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a perspective view of a main part of another example of the liquid crystal display unit.

FIG. 3 is an overall side view of the projection type liquid crystal display device of the embodiment.

FIG. 4 is a front view of the liquid crystal display device of FIG.

FIG. 5 is an explanatory diagram of a temperature difference distribution of a liquid crystal panel.

FIG. 6 is an explanatory diagram of an incident side deflection plate temperature difference distribution.

FIG. 7 is a main part diagram showing a flow of cooling air inside a liquid crystal display unit in a comparative example.

FIG. 8 is a diagram in which the temperature rises of the upper part, the central part, and the lower part of the liquid crystal panel near the cooling air outlet (cooling air outlet) of the ventilation part when only the lower part of the ventilation part is closed are plotted.

FIG. 9 is a diagram in which the temperature rises of the upper part, the central part and the lower part of the incident side polarization plate are similarly plotted.

FIG. 10 is a diagram showing an example of the flow of cooling air in the liquid crystal display unit in the case of the first embodiment.

FIG. 11 is a perspective view of a main part of another example of the liquid crystal display unit provided with the ventilation part according to the embodiment of the liquid crystal display device of the present invention.

FIG. 12 is a liquid crystal when the length H2 of the lower blocking member on the entrance side and the length H1 ′ of the upper blocking member on the exit side are kept constant and the amount (H1) of closing from the upper part of the blocking member of the polarizing plate on the entrance side is changed. It is the figure which plotted the temperature rise in the cooling air outlet side of the panel.

FIG. 13 is a diagram in which the temperature rise on the cooling air outlet side of the incident side deflection plate is plotted under the same conditions as in FIG.

FIG. 14 is a diagram showing another example of the flow of cooling air in the liquid crystal display unit in the case of the first embodiment.

FIG. 15 is a diagram showing a flow of cooling air in a configuration in which a cooling fan is provided below.

FIG. 16 is a perspective view of a main part showing a ventilation part of the liquid crystal display unit according to the second embodiment.

FIG. 17 is a sectional view of the cooling structure at right angles to the optical axis.

FIG. 18 is a diagram showing a flow of cooling air according to a modified example of the second embodiment.

FIG. 19 is an overall view of a conventional projection type liquid crystal display device.

FIG. 20 is a perspective view of a main part of a ventilation part of a conventional projection type liquid crystal display device.

[Explanation of symbols]

 1 Liquid crystal panel 2 Incident side polarizing plate 3 Emitting side polarizing plate 5 Holding part 6 Tape 7 Rib H1 Height with the upper part of the ventilation part closed H2 Height with the lower part of the ventilation part 11 Cooling fan 12 Projection lens 13 Light source lamp 14 Air Flow of air 15 Air flow path 16 Liquid crystal 17 Support material attached to the holding portion 18 Air flow path 18 Air flow paths 18a, 18b Upper and lower air flow paths 19 Cooling duct 20 Endothermic fin 21 Radiating fin 30 Liquid crystal display section 31 Cooling Wind inflow part 32 Cooling air outflow part 40 Ventilation part

Claims (5)

[Claims] 1. A liquid crystal display unit including a liquid crystal panel on which an image to be projected is displayed, and a light source for projecting light on the display unit, and an image is projected on an external projection surface by the transmitted light of the display unit. In the projection type liquid crystal display device, a ventilation part for passing cooling air is provided in the liquid crystal display part, and a blocking member for blocking a part thereof is provided at the cooling air inlet of the ventilation part. An air-cooling structure for a liquid crystal display device, characterized in that the cooling air is changed to be intensively guided to a target place requiring cooling. 2. The liquid crystal display unit includes a liquid crystal panel and a polarizing plate, and the closing member is configured to guide the cooling air toward the central portion of the liquid crystal panel and the polarizing plate. The air-cooled structure of the liquid crystal display device according to claim 1. 3. The closing member is a cooling air inflow port 0-4.
The air-cooled structure for the liquid crystal display device according to claim 1, wherein the air-cooled structure closes 0%. 4. The ventilation member between the liquid crystal panel and the incident side polarizing plate side is formed at the cooling air inflow port so as to project from an end portion along a width direction of the liquid crystal panel toward a central portion. 4. The first blocking member of the section and the second blocking member of the ventilation section between the liquid crystal panel and the emission side polarizing plate have different protrusion heights, respectively. The air-cooled structure for a liquid crystal display device according to any one of the above. 5. The liquid crystal display according to claim 1, wherein a cooling air passage for guiding cooling air to the cooling air inlet is integrally formed with a holding portion surrounding and holding the liquid crystal display portion in the plane direction. Air cooling structure of the device.