JP2002214605A - Liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem on the fluorescent lamp for light emission of a liquid crystal panel that its luminance is degraded by a temperature rise. SOLUTION: A thermal convection suppressing means is arranged in the lower part of the horizontally placed fluorescent lamp for light emission in order to suppress the temperature rise of the fluorescent lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating means in which a fluorescent lamp is disposed vertically affected by convection of heat, and a liquid crystal display device using the illuminating means.

[0002]

2. Description of the Related Art In recent years, liquid crystal panels have been steadily increasing in size, and as liquid crystal display devices, personal computers and displays for personal use, as well as family use mainly for television reception, have been used. Is expanding.

[0003] For these reasons, in the illumination means, which is the light source of the liquid crystal display device, various approaches have been taken to improve the size and increase the luminance.

FIG. 6 shows an example of a direct type backlight device which is one type of illumination means in a conventional liquid crystal display device.
There is an object shown in FIG. Reference numeral 1 denotes several fluorescent lamps serving as light sources, and 7 denotes a liquid crystal panel for displaying an image. Here, other components not involved in the description are omitted. As a light source of the liquid crystal panel 7 for displaying an image, the fluorescent lamp 1
Several are arranged horizontally on the back of the panel.

However, when a liquid crystal panel having a large display screen is used, such as a wide aspect of the liquid crystal panel as shown in FIG. 1B, it is necessary to lengthen the fluorescent lamp at the same time. Generally, a fluorescent lamp is required to have a high starting voltage as its length becomes longer, and the cost of a driving circuit tends to increase in terms of increasing the withstand voltage of components and differential driving.

Therefore, as a means for avoiding this, the length of the fluorescent lamp is shortened by arranging the fluorescent lamp not in the horizontal direction but in the vertical direction of the display screen as shown in FIG. . In this way, by increasing the size of the panel, and by adopting a wide aspect compatible with BS digital broadcasting, etc.,
For fluorescent lamps, which tend to be longer, the drive circuit is simplified and the size of the liquid crystal panel is increased.

Japanese Patent Application Laid-Open No. 4-358125 is an example of an edge light type backlight device which is one type of illumination means in a conventional liquid crystal display device. FIG. 7 shows a configuration of an edge type backlight device which is an illumination means in the conventional liquid crystal display device.

In FIG. 7, reference numeral 71 denotes a pair of L-type fluorescent lamps, which are light sources of the backlight device. A light guide 73 guides light emitted from the L-type fluorescent lamp to the display surface.
Reference numeral 6 denotes an L-type fluorescent lamp, a reflecting member that covers the light guide from behind the display surface, reflects light to the back surface, and reflects the light to the display surface. A diffusion device is mounted on the display surface side of the light guide 73 to form a backlight device, and a liquid crystal panel is further mounted thereon to constitute a liquid crystal display module.

The illuminating means in this conventional liquid crystal display device is different from the light guide plate 73 in that a fluorescent lamp is disposed on one or two sides (edges) by using an L-type fluorescent lamp. By arranging the light sources on the four sides, high brightness is realized.

As described above, with an increase in the size and brightness of a liquid crystal panel, the arrangement of fluorescent lamps in the vertical direction, which is the short side of the display screen, is increasing.

[0011]

In the conventional liquid crystal display device, as described above, when the fluorescent lamp is arranged in the vertical direction, which is the short side of the liquid crystal panel, the electrode portion, which is the main heat source of the fluorescent lamp, is provided. One is disposed below the fluorescent lamp, and heat generated in the electrode portion is transmitted along the fluorescent lamp arranged vertically by thermal convection, and the entire fluorescent lamp is burned by the heat of the electrode portion.

As a result, the temperature distribution of the fluorescent lamp itself is changed and biased as shown in FIG. 8B from the temperature distribution in the horizontal arrangement as shown in FIG. 8A.

The bias of the temperature distribution will be described in detail with reference to FIG. In FIG. 8, in section m, the mercury near the electrodes is depleted when the temperature difference is large due to the property that the filling in the lamp (eg, mercury) collects at the lowest temperature.
There is a possibility of causing a cataphoresis phenomenon that causes lighting failure, so that the temperature distribution in this section does not become uneven,
This is a section that needs to be considered.

Aa is the average temperature of the lamp in the section m in the horizontal arrangement, Ab is the average lamp temperature in the vertical arrangement, Ca is the hottest temperature in the horizontal arrangement, and Cb is the average temperature in the vertical arrangement. The same hottest point temperature, Da represents the same coldest point temperature in the horizontal arrangement, and Db represents the same coldest point temperature in the vertical arrangement. Here, in the horizontal arrangement of FIG. 8A, the hottest point temperature and the coldest point temperature in the section m are almost equal, and Ca = Da (= A
a).

In the vertical arrangement shown in FIG. 8B,
The lamp in the section m is burned by the heat of the electrode located at the lower end along the fluorescent lamp arranged vertically, the relationship between the hottest point temperature and the coldest point temperature becomes Cb> Db, and the horizontal arrangement is performed. In the vertical arrangement, the temperature rises due to the same factor as compared with the average temperature in the section m, and Ab> Aa. As a result, the lamp temperature gradient changes and the offset occurs.

As a result, the bias in the temperature distribution tends to cause the filling in the fluorescent lamp to be easily offset, which may cause a lighting failure due to the cataphoresis phenomenon.

An object of the present invention is to suppress the cataphoresis phenomenon that is likely to be caused by arranging a fluorescent lamp vertically, and to improve reliability such as defective lighting.

[0018]

In order to solve this problem, a liquid crystal display device according to a first aspect of the present invention is provided with a heat convection suppressing means for suppressing a heat convection generated by heat generated at an electrode portion of a fluorescent lamp. It is characterized by the fact that.

Thus, the heat convection is suppressed,
The temperature distribution of the fluorescent lamp can be equilibrated as in the case where the lamps are horizontally arranged, and the temperature distribution is equilibrated, whereby an effect of making it difficult to cause lighting failure due to the cataphoresis phenomenon is obtained.

Further, the liquid crystal display device according to the second aspect of the present invention is characterized in that the heat convection suppressing means for suppressing the heat convection generated by the heat generated at the electrode portion of the fluorescent lamp and the fluorescent lamp holding means are integrally formed. And

Thus, the heat convection is suppressed,
The temperature distribution of the fluorescent lamp can be equilibrated to the same level as when the lamp is arranged horizontally.By integrating the fluorescent lamp holding means and the heat convection suppressing means, the number of parts and man-hours are increased. As a result, the temperature distribution of the fluorescent lamp can be equilibrated, and the lighting failure due to the cataphoresis phenomenon is less likely to occur.

Further, the liquid crystal display device according to the third aspect of the present invention is characterized in that a heat convection suppressing means for suppressing heat convection caused by heat of the electrode portion and a heat radiating means of the lamp are integrally formed. As a result, heat convection is suppressed,
The temperature distribution of the fluorescent lamp can be equilibrated to the same level as when the lamp is arranged horizontally. By integrating the radiating means of the fluorescent lamp and the heat convection suppressing means, the number of parts and man-hours do not increase In addition, by effectively radiating the temperature around the electrode portion of the lamp chamber and balancing the temperature distribution of the fluorescent lamp, an effect of making it difficult to cause lighting failure due to the cataphoresis phenomenon can be obtained.

The liquid crystal display device according to the fourth aspect of the present invention is characterized in that the liquid crystal display device is formed of a material that transmits or diffuses light and that suppresses thermal convection caused by heat generated at the electrode portion of the fluorescent lamp. It is characterized by being provided.

[0024] Thus, since the light-transmitting or diffuse-reflecting material is molded, heat convection is suppressed without disturbing the output optical characteristics of the backlight device, and the temperature distribution of the fluorescent lamp is reduced. It is possible to balance the temperature distribution without disturbing the output optical characteristics of the backlight device, and it is possible to reduce the lighting failure due to the cataphoresis phenomenon. can get.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION
Suppresses the heat convection generated by the fluorescent lamps arranged vertically,
This is a liquid crystal display device using a lighting unit provided with a thermal convection suppressing unit as a light source, and has an effect of suppressing thermal convection generated by a fluorescent lamp arranged vertically.

According to a second aspect of the present invention, there is provided a fluorescent lamp arranged vertically, a thermal convection suppressing means which is made of resin or metal and is arranged near the fluorescent lamp to suppress thermal convection.
Lighting means comprising the fluorescent lamp and heat convection suppressing means,
This is a liquid crystal display device characterized in that the illuminating means is a light source, and has an effect of suppressing heat convection generated by a vertically arranged fluorescent lamp.

According to a third aspect of the present invention, there is provided the liquid crystal display device according to the first aspect, wherein the thermal convection suppressing means includes a means for holding the fluorescent lamp. The holding means has the function of suppressing the heat convection generated by the fluorescent lamp arranged vertically.

According to a fourth aspect of the present invention, there is provided a fluorescent lamp arranged vertically, a thermal convection suppressing means which is made of resin or metal and is arranged near the fluorescent lamp to suppress heat convection and a holding means for the fluorescent lamp. Is a liquid crystal display device characterized by being integrally formed with a lamp holding means, an illuminating means provided with the fluorescent lamp and the lamp holding means, and using the illuminating means as a light source. The holding means has the function of suppressing the heat convection generated by the fluorescent lamp arranged vertically.

According to a fifth aspect of the present invention, there is provided the liquid crystal display device according to the first aspect, wherein the heat convection suppressing means includes a means for radiating heat generated by the fluorescent lamp. The heat radiating means for radiating the temperature of the fluorescent lamp has an effect of suppressing heat convection generated in the fluorescent lamp arranged vertically.

According to a sixth aspect of the present invention, there is provided a fluorescent lamp arranged vertically, a heat convection suppressing means which is made of resin or metal and is arranged near the fluorescent lamp to suppress heat convection, and a heat radiating means for the fluorescent lamp. A liquid crystal display device, wherein a lamp radiating unit integrally formed with the fluorescent lamp, an illuminating unit including the fluorescent lamp and the lamp radiating unit, and the illuminating unit as a light source. Has the function of suppressing heat convection generated by the fluorescent lamp arranged vertically.

According to a seventh aspect of the present invention, there is provided the liquid crystal display device according to any one of the first to sixth aspects, wherein the thermal convection suppressing means includes a feature formed of a material that transmits light. In addition, it has an effect of suppressing thermal convection generated by a vertically arranged fluorescent lamp without disturbing the luminance distribution of the backlight device.

The invention according to claim 8 of the present invention is the liquid crystal display device according to any one of claims 1 to 6, wherein the thermal convection suppressing means includes a feature formed of a material which diffuses and reflects light. This has the effect of suppressing thermal convection generated by the fluorescent lamps arranged vertically without disturbing the luminance distribution of the backlight device.

(Embodiment 1) FIG. 1 shows a liquid crystal display device according to a first embodiment of the present invention.
Is a fluorescent lamp serving as a light source of the present liquid crystal display device, and 2 is any of the shapes shown in FIG. 2 as an example of a shape. is there. Reference numeral 6 denotes a reflection member that reflects light emitted from the fluorescent lamp 1 to the diffusion member 8 on the display surface. Reference numeral 8 denotes a diffusion member that averages the directivity of the light received from the fluorescent lamp 1 and the reflection member 6. Numeral 7 denotes a liquid crystal panel for displaying an image by controlling the amount of transmission of the light whose directionality is averaged by the diffusing member 8, and 9 denotes a lamp holding means for holding and fixing the fluorescent lamp 1. .

The operation of the liquid crystal display device configured as described above will be described.

When the fluorescent lamp 1 is energized, the temperature at this portion rises due to loss at the electrode portions at both ends. In particular, heat convection occurs in the space in the lamp room surrounding the fluorescent lamp 1 by the reflecting member 6 and the diffusing member 8 due to the heat generated below the fluorescent lamp 1. This heat convection rises along the outer wall of the fluorescent lamp 1, and a layer having a temperature higher than the lamp room space temperature covers the fluorescent lamp 1. However, since the heat convection suppressing means 2 is disposed, the heat convection is diffused and suppressed, so that a high temperature layer around the fluorescent lamp 1 is not formed, and the convection is changed to the entire convection in the lamp chamber.

As a result, the bias in the temperature distribution of the lamp is suppressed, and as a result, the bias in the filling in the fluorescent lamp can be suppressed. Therefore, a lighting failure due to a cataphoresis phenomenon caused by an uneven filling of the fluorescent lamp is less likely to occur, thereby improving reliability.

In this embodiment, three examples of the shape of the heat convection suppressing means are shown in FIG. 2, but the shape of the portion covering the lamp is such as O-shaped, U-shaped, concave, etc. It goes without saying that it is only necessary to be able to do so.

Further, in the present embodiment, the example of the direct type backlight device has been described as the illuminating means, but the present invention can be similarly realized by a side edge type backlight device.

As described above, like the temperature distribution characteristic of the fluorescent lamp shown in FIG. 8, in the temperature distribution characteristic a) when the fluorescent lamp is arranged horizontally, the average temperature of the lamp middle part is A.
The point a is the distribution characteristic b) in the case where the fluorescent lamp is arranged vertically, and the average temperature may increase to Ab in some cases, and the thermal convection suppressing means of the present invention suppresses the average temperature increase in this case. Things become possible. Therefore, it is also effective as a means for improving the luminous efficiency of the fluorescent lamp.

(Embodiment 2) FIG. 3 shows a liquid crystal display according to a second embodiment of the present invention. Hereinafter, only the portions having different configurations and operations from the first embodiment will be described. Numeral 10 denotes a lamp holding means having a heat convection suppressing mechanism for holding and fixing the fluorescent lamp 1 with a heat convection suppressing mechanism for suppressing heat convection due to heat generated at an electrode located below the fluorescent lamp 1.

The operation of the liquid crystal display device configured as described above will be described. When the fluorescent lamp 1 fixed by the lamp holding means 9 and the lamp holding means 10 with a heat convection suppressing mechanism is energized, the temperature at this portion increases due to loss at the electrode portions at both ends. In particular, heat convection occurs in the space in the lamp room surrounding the fluorescent lamp 1 by the reflecting member 6 and the diffusing member 8 due to the heat generated below the fluorescent lamp 1. This heat convection rises along the outer wall of the fluorescent lamp 1, and a layer having a temperature higher than the lamp room space temperature covers the fluorescent lamp 1. However, in the lower electrode portion of the fluorescent lamp 1, a heat convection suppressing mechanism is integrally formed with the lamp holding means 10, and the heat convection is diffused and suppressed by the heat convection suppressing mechanism.
Is not formed, and changes to convection throughout the lamp chamber.

As a result, the bias of the temperature distribution of the lamp is suppressed, and the bias of the filling in the fluorescent lamp can be suppressed. Further, since the heat convection suppressing mechanism is integrally formed with the lamp holding means, the number of parts and man-hours are the same as in the conventional case. Therefore, without increasing the number of parts and man-hours, the lighting failure due to the cataphoresis phenomenon caused by the uneven filling of the fluorescent lamp is less likely to occur, thereby improving the reliability.

In the present embodiment, the shape of the heat convection suppressing mechanism has been described with reference to the example of FIG. 2A. However, it is needless to say that the heat convection suppressing mechanism may have any shape that can suppress the heat convection.

Further, in this embodiment, the direct lighting type backlight device has been described as an example of the illuminating means. However, a side edge type backlight device can be similarly realized.

(Embodiment 3) FIG. 5 shows a liquid crystal display device according to a third embodiment of the present invention. In FIG. 5, 1
Is a fluorescent lamp as a light source, 4 is an electrode part of the fluorescent lamp 1, 6 is a reflecting member that covers the fluorescent lamp 1 and the light guide 3, and reflects light of the fluorescent lamp 1 to the light guide 3, and 3 is A light guide for outputting light from the fluorescent lamp 1 and the reflecting member 6 to the display surface, 8 is a diffusing means for averaging the directivity of the light from the light guide 3, and 7 is a directing light from the diffusing member 8. A liquid crystal panel for displaying an image by controlling the amount of transmission of the light having averaged properties, and 11 is a fluorescent lamp 1 and a reflecting member 6.
Further, a heat conduction path is provided between the backlight unit and the space outside the backlight device, and a heat radiation means for dissipating heat and a heat radiation means having a heat convection suppressing mechanism having a mechanism for suppressing heat convection due to heat generated at the electrode portion of the fluorescent lamp 1. is there.

The operation of the liquid crystal display device configured as described above will be described. The fluorescent lamp 1 is energized and the electrode 4
Is generated in the space inside the lamp chamber surrounding the fluorescent lamp 1 by the reflection member 6 and the diffusion member 8. The heat convection rises along the outer wall of the fluorescent lamp 1, and a layer having a temperature higher than the lamp room space temperature covers the fluorescent lamp 1.

However, since the heat radiating means 11 with the heat convection suppressing mechanism is provided, in the lamp room space located above this part,
Thermal convection is greatly suppressed. On the other hand, the temperature of the space between the lamp electrode 4 and the radiator 11 with the heat convection suppressing mechanism rises, so to speak. In the member 6, a heat conduction path is formed with the space outside the backlight device, which is the outer wall of the reflection member 6, and the heat radiation means 11 with the heat convection suppressing mechanism is formed by the fluorescent lamp 1 and the lamp electrode 4. The heat in the space between them can be dissipated.

As a result, the unevenness of the temperature distribution of the lamp is suppressed, and the unevenness of the filling in the fluorescent lamp can also be suppressed. Further, since the heat convection suppressing mechanism is integrally formed with the heat radiating means, the number of parts and man-hours are the same as those of the related art, and heat can be efficiently radiated. Therefore, without increasing the number of parts and man-hours, the temperature around the electrode section of the lamp room is efficiently radiated, and the temperature distribution of the fluorescent lamp is balanced, so that lighting failure due to the cataphoresis phenomenon is less likely to occur, improving reliability. Is done.

(Embodiment 4) FIG. 1 shows a liquid crystal display device according to a fourth embodiment of the present invention. Hereinafter, only the portions having different configurations and operations from the first embodiment will be described. 2 is a shape example shown in FIG. 2 and is formed of a material that transmits or diffuses and reflects light, and suppresses heat convection due to heat generated at an electrode located below the fluorescent lamp 1. It is.

The operation of the liquid crystal display device configured as described above will be described. When the fluorescent lamp 1 is energized, the temperature at this portion increases due to loss at the electrode portions at both ends.
In particular, heat convection occurs in the space in the lamp room surrounding the fluorescent lamp 1 by the reflecting member 6 and the diffusing member 8 due to the heat generated below the fluorescent lamp 1. This heat convection rises along the outer wall of the fluorescent lamp 1, and a layer having a temperature higher than the lamp room space temperature covers the fluorescent lamp 1. However, since the heat convection suppressing means 2 is disposed, the heat convection is diffused and suppressed, and a high temperature layer around the fluorescent lamp 1 is not formed.
It changes to convection in the whole lamp room.

Further, since the thermal convection suppressing means 2 is constituted by means for transmitting or diffusing and reflecting light, the provision of the thermal convection suppressing means 2 allows the optical characteristics of the backlight device such as shadows to be obtained. Does not significantly disturb.

As a result, the bias of the temperature distribution of the lamp is suppressed without greatly disturbing the output optical characteristics of the backlight device, and as a result, the bias of the filling in the fluorescent lamp can be suppressed. Therefore, a lighting failure due to a cataphoresis phenomenon caused by an uneven filling of the fluorescent lamp is less likely to occur, thereby improving reliability.

Although the present embodiment has been described with respect to the case where the heat convection suppressing means is formed of a material which transmits light, it can be similarly realized when formed of a material which diffuses and reflects light.

[0054]

As described above, according to the present invention, since the temperature distribution is balanced by the thermal convection suppressing means, it is possible to obtain an effect of making it difficult to cause lighting failure due to the cataphoresis phenomenon.

Further, by integrating the fluorescent lamp holding means and the thermal convection suppressing means, it becomes possible to balance the temperature distribution of the fluorescent lamp without increasing the number of parts and man-hours. The effect of making defects less likely to be obtained is obtained.

Further, by integrating the heat radiating means of the fluorescent lamp and the heat convection suppressing means, the temperature around the electrode portion of the lamp chamber can be efficiently radiated without increasing the number of parts and man-hours, and the temperature distribution of the fluorescent lamp can be improved. The effect of reducing lighting failure due to the cataphoresis phenomenon can be obtained by balancing.

Further, since the temperature distribution is balanced without disturbing the output optical characteristics of the backlight device, an effect of making it difficult to cause lighting failure due to the cataphoresis phenomenon can be obtained.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a liquid crystal display device according to first and fourth embodiments of the present invention.

FIG. 2 is an external view showing an example of a shape of a thermal convection suppressing means.

FIG. 3 is a structural diagram of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is an external view showing an example of a lamp holding unit with a thermal convection suppressing mechanism.

FIG. 5 is a structural diagram of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a layout diagram of a fluorescent lamp in a conventional direct-type backlight.

FIG. 7 is a structural diagram of a conventional liquid crystal display device using an L-shaped edge light.

FIG. 8 is a characteristic diagram showing an example of a temperature distribution of a fluorescent lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluorescent lamp 2 Heat convection suppressing means 3,73 Light guide 4 Lamp electrode 6,76 Reflecting member 7 Liquid crystal panel 8 Diffusion member 9 Lamp holding means 10 Lamp holding means with a heat convection suppressing mechanism 11 Heat radiating means with a heat convection suppressing mechanism 71 L-type fluorescent lamp

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G09F 9/00 337 G09F 9/00 337Z (72) Inventor Hirofumi Yamashita 1006 Ojidoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H091 FA41Z FA42Z LA04 5G435 AA03 AA12 BB03 BB12 BB15 EE26 FF06 GG24 GG26

Claims (8)

[Claims] 2. A liquid crystal display device comprising: a lighting unit having a heat convection suppressing means for suppressing a heat convection generated by a fluorescent lamp arranged vertically; 2. A fluorescent lamp arranged vertically, a heat convection suppressing means made of resin or metal and arranged near the fluorescent lamp to suppress heat convection, and an illuminating means provided with the fluorescent lamp and heat convection suppressing means. A liquid crystal display device characterized in that the lighting means is a light source. 3. The liquid crystal display device according to claim 1, wherein said thermal convection suppressing means includes means for holding said fluorescent lamp. 4. A fluorescent lamp arranged vertically, and a lamp holding means which is made of resin or metal and which is integrally formed with a heat convection suppressing means which is arranged near the fluorescent lamp and suppresses heat convection and a holding means of the fluorescent lamp. A liquid crystal display device comprising: a lighting unit including the fluorescent lamp and the lamp holding unit; and the lighting unit serving as a light source. 5. The liquid crystal display device according to claim 1, wherein said heat convection suppressing means includes means for radiating heat generated by said fluorescent lamp. 6. A fluorescent lamp arranged vertically, a heat convection suppressing means which is made of resin or metal and is arranged near the fluorescent lamp and suppresses heat convection, and a lamp heat radiating means integrally formed with a heat radiating means of the fluorescent lamp. A liquid crystal display device comprising: an illuminating unit having the fluorescent lamp and the lamp radiating unit; and the illuminating unit being a light source. 7. The liquid crystal display device according to claim 1, wherein said thermal convection suppressing means includes a feature formed of a material that transmits light. 8. The liquid crystal display device according to claim 1, wherein said thermal convection suppressing means includes a feature formed of a material that diffuses and reflects light.