JP2001133780A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the emission efficiency of a double-pipe fluorescent lamp and to prevent decrease in luminance by suppressing heat radiation at the end of the fluorescent tube. SOLUTION: The heat conduction is suppressed by using a material having a small heat radiation effect for the lamp supporting material 9 to be disposed on the electrode part of a double-pipe fluorescent lamp 8 and by forming a lacked part to avoid contact with the lamp supporting material 9 in the lower frame to be attached to the electrode part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device capable of suppressing a decrease in luminance of an illumination light source and always displaying a high luminance.

[0002]

2. Description of the Related Art A liquid crystal display device used as a display means of a personal computer or another monitor irradiates an image generated on a liquid crystal panel with illumination light and emits the transmitted light or reflected light to the display surface side. To visualize.

That is, in this type of liquid crystal display device, generally, a liquid crystal layer is sandwiched in a bonding gap between a pair of substrates having pixel selection electrodes and the like, and a polarizing plate or a phase difference plate is provided on one or both surfaces thereof. An image is generated by laminating a polarizing plate and changing the alignment state of liquid crystal molecules in a selected pixel portion. Since the generated image is not in a visible state by itself, external light is applied to illuminate the LCD panel,
It is configured to observe the transmitted light or the reflected light.

In a liquid crystal display device for a notebook personal computer or a display monitor, a backlight in which an illumination light source is arranged on the back of a liquid crystal panel is mainly used. On the other hand, in the case of a PDA (small portable information terminal) or the like having a limited power supply capacity, the capacity of the mounted power supply itself is small, so that the liquid crystal display device does not include an active light source such as a backlight as an illumination light source. In many cases, ambient light is taken in and used as illumination light. However, in order to enable use in an environment where there is little ambient light or no external light, an auxiliary light source is arranged so that it can be used in a dark environment.

[0005] A backlighting device (hereinafter also referred to as a backlight) includes a sidelight type in which a linear light source such as a fluorescent lamp is arranged on a side edge of a light guide plate installed on the backside of a liquid crystal panel, and a backlight directly below the liquid crystal panel. And a direct type in which a plurality of the linear light sources are arranged.

FIG. 11 is an exploded perspective view for explaining a configuration example of a transmission type liquid crystal display device. A light guide plate 5 housed in a frame-shaped intermediate frame (intermediate mold case) 4 formed of a resin material is provided on the back surface of the liquid crystal panel 3, and a fluorescent lamp 8 is installed as a linear light source on a side edge of the light guide plate 5. The upper frame 1 of the metal plate provided on the display surface side (front surface side) of the liquid crystal panel and the lower frame 6 provided on the back surface of the light guide plate 5 are connected and integrated.

The backlight is provided with a light guide plate 5, a fluorescent tube 8, and rubber bushes (lamp support) 9 having a function of holding a power supply lead 10 at both ends of the fluorescent tube 8. Light plate 5 is placed in intermediate mold case 4
And the fluorescent tube 8 is housed in the light source housing 4A formed in the intermediate mold case 4.

On the periphery of the liquid crystal panel 3, the drive circuit board 2
A and 2B are attached. In an active matrix type liquid crystal display device such as a thin film transistor type, the driving circuit substrate 2A is generally a drain-side driving circuit substrate (drain driver), and the driving circuit substrate 2B is a gate-side driving circuit substrate (gate driver).

Then, a lamp reflecting sheet 7 is attached along the outer surface of the fluorescent tube 8, and is fixed by being sandwiched between the upper frame 1 and the lower frame 6 of the metal material from above and below. Needless to say, a window for exposing the screen of the liquid crystal panel 3 is opened in the upper frame 1, and the periphery is bent toward the lower frame, and claws, projections, and the like for coupling with the lower frame 6 are formed. .

As the fluorescent lamp 8, a cold cathode fluorescent tube is often used, and a mercury and a mixed gas of neon and argon of several tens torr are sealed in a glass tube having an inner diameter of several mm coated with a fluorescent film. Electrodes are provided at opposite ends.

[0011] Then, a high voltage of several hundred volts is applied between the electrodes, and mercury vapor is generated by the heat generated by the discharge generated between the two electrodes. Ultraviolet rays generated by the excitation of the mercury vapor stimulate the fluorescent film to be visible. Emit light. Therefore, as the amount of heat generated by increasing the current flowing through the fluorescent tube is increased, higher luminance is obtained. As this fluorescent lamp, there is one using a so-called double tube fluorescent lamp. Hereinafter, the double tube fluorescent lamp will be described with reference numeral 8.

FIG. 12 is a schematic sectional view of an essential part for explaining a structural example of a double tube fluorescent lamp. This double tube fluorescent lamp 8 is a mantle tube 8
A and an inner tube 8B, and a space between the outer tube 8A and the inner tube 8B is evacuated. An electrode 8D having an electrode terminal 8C penetrating outside is provided on the inner tube 8B at the distal end of both tubes.

A phosphor film 8E is coated on the inner surface of the inner tube 8B, and the enclosed mercury 8F is evaporated by heating the electrode 8D to stimulate the phosphor film 8E with ultraviolet rays to emit light, and the outer tube is converted to visible light. Emit from 8A.

FIG. 13 is a plan view of an essential part for explaining an example of an arrangement state of the double tube fluorescent lamp and the light guide plate. In the drawing, reference numeral 5 denotes a light guide plate, and reference numeral 6 denotes a lower frame, which is held by an intermediate mold case (not shown). The double tube fluorescent lamp 8 is fixedly accommodated in the light source accommodating portion 4A (see FIG. 11) of the intermediate mold case by a lamp support, a so-called bush 9. Generally, this bush 9 is made of silicone rubber.

The lower frame 6 has a function of diffusing heat from the lamp supporting member 9 to the entire display surface, has a good thermal conductivity, and is made of an aluminum material for reducing the weight of the liquid crystal panel 3.

As described above, both the conventional lamp support 9 and the lower frame 6 have a function and a structure for dissipating the heat from the double tube fluorescent lamp. By employing a double tube fluorescent lamp having this structure as a light source for a backlight, a liquid crystal display device with low power consumption can be obtained. As a conventional technique which discloses this type of double tube fluorescent lamp, Japanese Patent Application Laid-Open No. 8-334760 can be mentioned.

[0017]

In the above prior art, the lamp support (rubber bush) 9 is in contact with the lower frame, and when it is mounted on an electronic device, its mounting portion (for example, a lid of a personal computer). Part) through the double tube fluorescent lamp 8
Is released from the lamp supporting member 9 to the lower frame 6 and further to the mounting portion, so that the temperature of the lamp supporting member 9, that is, the end of the fluorescent tube 8 is accelerated.

The mercury vapor collects at the end of the double-tube fluorescent lamp 8 where the temperature has dropped, and is cooled and aggregates to form mercury particles (see FIG. 12). As a result, most of the mercury is collected at the end of the fluorescent tube 8 by driving for a long time, and the amount of generated mercury vapor is reduced in the entire fluorescent tube, and as a result, the emission luminance is reduced.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to suppress the heat radiation at the end of the fluorescent tube to secure the mercury vapor in the entire region of the fluorescent tube, thereby preventing the occurrence of a decrease in luminance. A display device is provided.

[0020]

In order to achieve the above-mentioned object, the present invention provides a lamp supporting member provided at an end of a double tube fluorescent lamp, that is, an electrode portion, using a material having a small heat radiation effect. The heat conduction is suppressed by forming a missing portion at the position of the lower frame corresponding to the above. Hereinafter, typical configurations of the present invention are listed as follows.

(1) A liquid crystal panel, a driving circuit for driving the liquid crystal panel, and an illuminating device having a double tube fluorescent lamp as a constituent element, and a foamed resin material around an electrode portion of the double tube fluorescent lamp A heat insulating fixing material consisting of

(2): a liquid crystal panel having a driving circuit on the periphery, a backlighting device having a double tube fluorescent lamp arranged along the side edge of the light guide plate and installed on the back of the liquid crystal panel,
A liquid crystal display device in which the liquid crystal panel and the back lighting device are integrally fixed by connecting an upper frame and a lower frame of a metal material provided on the front side of the liquid crystal panel and the back surface of the back lighting device, respectively. And a heat insulating fixing member made of a foamed resin material was provided on the outer periphery of the vicinity of the electrode portion of the double tube fluorescent lamp, and a lacking portion was formed in an installation area of the heat insulating fixing material on the lower frame.

(3): The heat insulating fixing material in (2) was made of a polystyrene foam material. As the heat insulating fixing material, other materials may be used as long as they have the same properties as the heat insulating effect, the heat resistance effect, and the fixing and supporting effect of the styrofoam material.

According to each of the above structures, the temperature drop of the electrode portion of the double tube fluorescent lamp is suppressed, the temperature difference between the central region of the double tube fluorescent lamp and the electrode portion is suppressed, and the mercury vapor in the tube is condensed. Therefore, a decrease in the luminance of the backlight is prevented.

The present invention is not limited to the above configuration, and various modifications can be made without departing from the technical idea of the present invention.

[0026]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a main part showing the structure of an electrode portion of a double tube fluorescent lamp for explaining a first embodiment of the liquid crystal display device of the present invention. In the present embodiment, a double tube fluorescent lamp having an outer tube 8A and an inner tube 8B is used as a light source (linear light source) constituting a backlight of a liquid crystal display device, and electrode portions at both ends of the double tube fluorescent lamp 8 are used. The lamp support member to be installed in the first embodiment is formed of styrene foam resin.

The outer shape of the lamp supporting member 9 is substantially rectangular, and has a hollow opening for fitting the end (electrode portion) of the double tube fluorescent lamp 8 on one surface. This cavity has a bottom, but may be a tunnel penetrating the opposite side.

The electrode portion of the double tube fluorescent lamp 8 has an electrode terminal 8C.
A power supply lead 10 (see FIG. 11) connected to a power supply unit (not shown) of the liquid crystal display device is soldered to the electrode terminal 8C, but is omitted in this figure.

According to the present embodiment, the electrode portion of the double tube fluorescent lamp 8 is installed by installing the double tube fluorescent lamp 8 to which the lamp supporting member 9 is attached, in the intermediate mold frame as shown in FIG. It is insulated and the temperature drop is suppressed. as a result,
Heat radiation from the electrode portion is suppressed, and the liquid crystal panel can be illuminated with high luminance without a decrease in light emission luminance.

FIG. 2 is a schematic sectional view of a main part showing the structure of an electrode part of a double tube fluorescent lamp for explaining a second embodiment of the liquid crystal display device of the present invention. Also in this example, the lamp support members 9 installed at the electrode portions at both ends of the double-tube fluorescent lamp 8 were formed of styrene foam resin.

This embodiment is different from the first embodiment in that:
The outer shape of the lamp support member 9 is substantially cylindrical, and one end surface of the lamp support member 9 has a cavity opening for fitting an end portion (electrode portion) of the fluorescent tube 8. This cavity is bottomed,
It may be a tunnel shape penetrating to the opposite side.

Also in this embodiment, the double tube fluorescent lamp 8 to which the lamp supporting member 9 is attached is installed in the intermediate mold frame as shown in FIG.
The electrode portion is insulated and the temperature drop is suppressed. As a result, heat radiation from the electrode portion is suppressed, and the liquid crystal panel can be illuminated with high luminance without a decrease in light emission luminance.

FIG. 3 is a plan view of an essential part for explaining the arrangement of the lower frame and the backlight of the liquid crystal display device of the present invention. FIG. 4 is a partial sectional view taken along line AA of FIG.

As shown in FIG. 4, the double tube fluorescent lamp 8 is
Utilizing the elastic deformation of the lamp supporting member 9, the lamp supporting member 9 is fixed by being pushed into the light source housing portion 4 </ b> A of the intermediate mold frame 4. The fluorescent tube 8 is fixed at a position facing the side surface of the light guide plate 5 also incorporated in the intermediate mold frame 4.

The lamp supporting member 9 is made of the styrofoam resin described with reference to FIG. 1 or FIG. 2, and a portion corresponding to the electrode portion of the double tube fluorescent lamp 8 of the lower frame 6 constituting the liquid crystal display device (the lamp supporting member 9). The opening 6A is formed so as to lack the portion where the is located.

The double tube fluorescent lamp 8 is fixed at a predetermined position by fitting the lamp supporting member 9 into a concave portion of the light source housing 4A formed in the frame-shaped intermediate mold case 4. The double tube fluorescent lamp 8 is fixed at a position facing the edge (side end) of the light guide plate 5 housed in the intermediate mold case 4.

With this configuration, most of the heat from the electrode section is insulated by the styrofoam resin lamp support member 9, and the heat radiated outside via the lamp support member 9 is also reduced by the lower frame 6.
The heat is prevented from escaping from the lamp support member 9 to the lower frame 6 by the cutout opening 6A. Lower frame 6
6A is not limited to a rectangular shape, but a circular shape.
It may be oval, diamond, or any other shape that does not contact the lamp support 9.

As a result, the temperature drop of the electrode portion of the double tube fluorescent lamp 8 is significantly reduced, and the aggregation of mercury vapor due to the temperature drop of the double tube fluorescent lamp 8 is suppressed. Since the amount of mercury vapor in the inside is sufficiently ensured, there is no decrease in the amount of emitted light, so that high-luminance illumination can be obtained.

FIG. 5 is a plan view of an essential part for explaining another example of the arrangement of the lower frame 6 and the backlight of the liquid crystal display device of the present invention. Here, the notch formed in the lower frame 6 is a notch 60A. A lamp support member 9 that covers the electrode portion of the double tube fluorescent lamp 8 is provided in the cutout portion 60A. Even with this configuration, most of the heat from the electrode section is insulated by the styrofoam resin lamp support member 9, and the heat that passes through the lamp support member 9 to the outside is also isolated by the cutout portion 60 </ b> A of the lower frame 6.
The escape of heat from the lamp support member 9 to the lower frame 6 is prevented. The opening provided in the lower frame 6 is not limited to the rectangular shape of the cutout portion 60 </ b> A, but may be a circular shape, an elliptical shape, a diamond shape, or any other shape that does not contact the lamp support member 9.

As a result, the temperature drop of the electrode portion of the double tube fluorescent lamp 8 is significantly reduced, and the aggregation of mercury vapor due to the temperature drop of the double tube fluorescent lamp 8 is suppressed. Since the amount of mercury vapor in the inside is sufficiently ensured, there is no decrease in the amount of emitted light, so that high-luminance illumination can be obtained.

FIG. 6 is an exploded perspective view for explaining the overall structure of the liquid crystal display device of the present invention. The structure of the lower frame 6 has the structure described in FIG. 9 has the configuration of the first embodiment described with reference to FIG. However, the same applies to the case where the lamp supporting member 9 of the double tube fluorescent lamp 8 adopts the structure of the second embodiment described with reference to FIG.

The main part of the structure of this liquid crystal display device is the same as that of FIG. 11 except that an opening 6A is formed in the lower frame 6, so that the description will not be repeated.

In FIG. 6, the double tube fluorescent lamp 8 has the lamp supporting member 9 fitted into concave portions formed at both end portions of the light source housing portion 4A of the intermediate mold case 4. The opening 6A of the lower frame 6 is located at a portion located immediately below the portion where the lamp support member 9 is fitted. The lamp reflection sheet 7 is provided so as to cover the opposite side of the double tube fluorescent lamp 8 from the light guide plate 5 and the upper and lower surfaces.

The liquid crystal display device shown in FIG. 6 is of a backlight type used for general electronic equipment such as a notebook computer and a display monitor.

FIG. 7 is a schematic view for explaining a schematic configuration for a portable information terminal to which the liquid crystal display device according to the present invention is applied, 3 is a transmissive liquid crystal panel, 5 is a light guide plate, and 8 is a double tube fluorescent light. A lamp, 20 indicates a touch panel, and 21 indicates a protective film.

This liquid crystal display device for a portable information terminal uses a double-tube fluorescent lamp 8 having the structure of any of the above-described embodiments and the lamp support member 9 as a backlight. A touch panel 20 for pen input is installed on the upper part of the liquid crystal panel 3, and a protective film 21 for abrasion resistance and for preventing external light reflection is laminated on the upper surface of the touch panel 20.

FIG. 8 is a perspective view of a notebook personal computer, which is an example of information equipment on which the liquid crystal display device according to the present invention is mounted. This notebook personal computer comprises a main body that houses a keyboard (host computer) including a CPU and a CPU, and a display unit. A liquid crystal display device (liquid crystal display module MDL) having the configuration of the embodiment of the present invention is mounted on the display unit, and the liquid crystal panel PNL forms a screen.
FPC1 is a printed board on which a gate driver is mounted, FPC2 is a printed board on which a drain driver is mounted, PCB is an interface board for supplying display signals and the like from the main body to the liquid crystal display device MDL via a cable, and LPC is The double tube fluorescent lamp, IV, is a power source for the backlight. The display unit is attached to the main body by a main body hinge so as to be openable and closable. In the figure, arrows indicate the flow of signals.

FIG. 9 is a front view of a display monitor which is another example of the information equipment on which the liquid crystal display device according to the present invention is mounted. This display monitor includes a display unit and a stand unit. In addition, a host computer or a television receiving circuit can be stored in the stand section,
Display monitors are not limited to PC monitors,
It can also be applied as a television receiver.

FIG. 10 is an explanatory diagram of an external appearance example of a portable information terminal which is still another example of an information device equipped with the liquid crystal display device according to the present invention. In the figure, 47 is an information processing device (PD
A) a main unit, 48 is a display unit of the information processing device 47, 49
Denotes a keyboard unit of the information processing device 47, 50 denotes a host computer (host) for performing information processing of the information processing device 47, 51 denotes a microprocessor (MPU), 52 denotes a battery, 53 denotes a connection between the liquid crystal display device 46 and the host 50. An interface cable, 54 is an inverter power supply for the lighting device, 55 is a cable connecting the inverter power source 54 and the light source 14 of the lighting device, 56 is a pen for inputting information using a touch panel, and 57 is a housing for the pen 56. Reference numeral 60 denotes a mobile phone, 61 denotes a cable for connecting the mobile phone and the information processing device 47.

In the information processing device 47, the liquid crystal display device 46 is provided on the display section 48 of the information processing device 47. According to this liquid crystal display device, the touch panel described with reference to FIG. 7 is provided so as to overlap with the display unit 48. Therefore, by pressing a predetermined portion with a pen 56 or a finger, a character 58 can be input or an icon 59 can be input. Can be selected to execute the software function. Further, the liquid crystal display device 46 of this application example uses a reflective liquid crystal panel, and when there is external light such as sunlight, the power consumption can be suppressed by switching off the inverter power supply 54 and the battery 52.
Consumption can be reduced.

The shape and structure of each of the above embodiments of the present invention and each applicable information device are not limited to those shown in the drawings, but may have various shapes, structures and functions.

[0053]

As described above, according to the present invention,
The temperature drop of the electrode part which is the end part of the double tube fluorescent lamp is suppressed, the temperature difference between the central part of the tube and the electrode part can be reduced, and the mercury aggregated at the end of the tube due to the temperature drop due to the heat radiation of the electrode part It is possible to suppress a decrease in the brightness of the backlight caused by a reduction in luminous efficiency due to the aggregation of particles. As a result, a highly reliable liquid crystal display device with high luminance can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part showing a structure of an electrode part of a double tube fluorescent lamp for explaining a first embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a schematic cross-sectional view of a main part showing a structure of an electrode portion of a double tube fluorescent lamp for explaining a second embodiment of the liquid crystal display device of the present invention.

FIG. 3 is a main part plan view for explaining the arrangement of a lower frame and a backlight of the liquid crystal display device of the present invention.

FIG. 4 is a partial sectional view taken along line AA of FIG. 3;

FIG. 5 is a main part plan view for explaining another configuration example of the arrangement of the lower frame and the backlight of the liquid crystal display device of the present invention.

FIG. 6 is an exploded perspective view illustrating the overall configuration of the liquid crystal display device of the present invention.

FIG. 7 is a schematic diagram illustrating a schematic configuration for a portable information terminal to which the liquid crystal display device according to the present invention is applied.

FIG. 8 is a perspective view of a notebook personal computer, which is an example of an information device equipped with the liquid crystal display device according to the present invention.

FIG. 9 is a front view of a display monitor which is another example of the information equipment on which the liquid crystal display device according to the present invention is mounted.

FIG. 10 is an explanatory diagram of an external appearance example of a portable information terminal, which is still another example of an information device equipped with the liquid crystal display device according to the present invention.

FIG. 11 is an exploded perspective view illustrating a configuration example of a transmission type liquid crystal display device.

FIG. 12 is a schematic cross-sectional view of a main part illustrating a structural example of a double tube fluorescent lamp.

FIG. 13 is a main part plan view for explaining an example of an arrangement state of a double tube fluorescent lamp and a light guide plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper frame 2A, 2B Drive circuit board 3 Liquid crystal panel 4 Intermediate mold case 4A Light source storage part 5 Light guide plate 6 Lower frame 6A, 60A Missing part 7 Lamp reflection sheet 8 Double tube fluorescent lamp 8A Mantle tube 8B Inner tube 8C Electrode terminal 8D electrode 8E phosphor film 8F mercury 9 lamp support 10 power supply lead.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiro Sugaya 3681 Hayano Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Yuichi Yoshino 3681 Hayano Mobara-shi Chiba Prefecture F-term in Hitachi Device Engineering Co., Ltd. Reference) 2H091 FA42Z FB02 FD13 LA04 LA16 LA30 5G435 AA03 AA12 BB12 BB15 EE03 EE04 EE05 EE27 EE29 FF08 GG24 HH02 LL07 LL08

Claims (3)

[Claims] The present invention has a liquid crystal panel, a driving circuit for driving the liquid crystal panel, and an illuminating device having a double tube fluorescent lamp as a constituent element. A liquid crystal display device comprising a heat insulating fixing material. 2. A liquid crystal panel having a driving circuit on a peripheral edge thereof, a back lighting device having a double tube fluorescent lamp arranged along a side edge of a light guide plate and installed on a back surface of the liquid crystal panel, and the liquid crystal panel. A liquid crystal display device comprising a liquid crystal panel and a rear lighting device integrally fixed by connecting an upper frame and a lower frame of a metal material provided on a front side of the rear lighting device and a rear surface of the rear lighting device, respectively. A liquid crystal display device comprising: a heat insulating fixing member made of a foamed resin material on an outer periphery near an electrode portion of the double-tube fluorescent lamp; and a lacking portion formed in an installation area of the heat insulating fixing material on the lower frame. . 3. The liquid crystal display device according to claim 2, wherein said heat insulating fixing member is made of a styrene foam resin.