JP2002279813A - Lighting unit, and liquid crystal display device using the same - Google Patents

Lighting unit, and liquid crystal display device using the same

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Publication number
JP2002279813A
JP2002279813A JP2001077629A JP2001077629A JP2002279813A JP 2002279813 A JP2002279813 A JP 2002279813A JP 2001077629 A JP2001077629 A JP 2001077629A JP 2001077629 A JP2001077629 A JP 2001077629A JP 2002279813 A JP2002279813 A JP 2002279813A
Authority
JP
Japan
Prior art keywords
light
reflector
guide plate
liquid crystal
light source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2001077629A
Other languages
Japanese (ja)
Inventor
Toshihiko Ura
敏彦 裏
Original Assignee
Matsushita Electric Ind Co Ltd
松下電器産業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Ind Co Ltd, 松下電器産業株式会社 filed Critical Matsushita Electric Ind Co Ltd
Priority to JP2001077629A priority Critical patent/JP2002279813A/en
Publication of JP2002279813A publication Critical patent/JP2002279813A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To effectively radiate heat generated at a light source and conducted to a reflector through a radiator plate, and to keep the displaying quality of a display surface of the liquid crystal display panel even when a light guide plate becomes bigger than a reflection sheet caused by the fluctuation of production. SOLUTION: The lighting unit comprises a light source 2, a light guide plate 3 guiding the light from the light source, a reflector 4 of which, at least a back side surface 2b is made of metal, arranged so as to surround the light source 2 and reflecting the light toward the light guide plate 3, a reflection sheet 5 reflecting the light entered into the light guide plate, and a radiation plate 6 made of metal, covering the back surface of the reflection sheet 5 in order to radiate the heat generated at the light source and conducted to the reflector 4. One end side of the reflector 4 of which, the front surface side is clasped by the reflection sheet 5, and the back surface side is clasped by a radiation plate 6 made of metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination unit used for a liquid crystal display device and the like, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art In recent years, display devices for information devices, such as notebook personal computers and word processors, and display devices for video devices, such as portable televisions, video movies, and car navigation systems, have become lighter and thinner.
Liquid crystal display devices have come to be widely used taking advantage of the feature of low power consumption. Many of these liquid crystal display devices have a configuration in which illumination light is applied from behind a display element by a built-in illumination unit in order to realize a bright display screen.

In this illumination unit, an edge light system in which a light guide plate is placed on the back surface of a display element and a line light source such as a fluorescent discharge tube is arranged on an end face of the light guide plate is excellent in thickness reduction and uniformity of luminance of a light emitting surface. As a backlight system of a liquid crystal display device used in a notebook personal computer or the like, an edge light system is often employed in order to give priority to thinness. In a liquid crystal display device used for a portable television, a car navigation system, and the like, an edge light system in which light sources are arranged on both left and right sides of a light guide plate or an edge light arranged only on one side in order to achieve both thinness and luminance. In many cases, the system is adopted.

FIG. 5 shows a conventional edge light type illumination unit UT in which light sources are arranged on both sides of a light guide plate, and a liquid crystal display device L having the same. This lighting unit UT
A flat transparent light guide plate 3 that transmits light to the entire back surface, light sources 2 disposed on both left and right sides of the light guide plate 3, and a reflection sheet that guides light emitted from the light source 2 to an end surface 3 a of the light guide plate 3. 5
Is arranged. The light guide plate 3, the reflection sheet 5, and a heat radiating plate 6, which will be described later, and the like constitute a lighting unit UT by being held by the housing 10.

[0005] The light guide plate 3 is formed of a material such as a transparent acrylic material whose optical characteristics represented by a transmittance and a refractive index necessary for light transmission are optimal. The reflection sheet 5 has a role of returning light that goes out of the light guide plate 3 back into the light guide plate 3 and increasing illumination light that goes out of the light exit surface. As the reflection sheet 5, a white resin film having a high reflectance is used. The light guide plate 3 and the reflection sheet 5 may be larger than the light guide plate 3 due to manufacturing variations.

The reflector 4 allows the light from the light source 2 to efficiently enter the incident end face 3 a of the light guide plate 3.
Are bent in a U-shaped cross section or a U-shaped cross section so as to surround. The reflector 4 is formed by coating a synthetic resin as a reflection surface on a metal such as aluminum. The housing 10 is arranged close to the side surface of the reflector 4 so as to surround it from above. The housing 10 includes the reflector 4
Of the light source 2, the light guide plate 3, the reflector 4, the reflection sheet 5, and the heat radiation plate 6.

The heat radiating plate 6 controls the heat generated by the light source 2 by the reflector 4.
And is made of a metal plate, and covers the reflection sheet 5 along the back surface of the reflection sheet 5. The lower end of the reflector 4 formed in a substantially U shape is in contact with the left and right ends of the rear surface of the heat sink 6 from the rear surface. Therefore, the heat transmitted to the reflector 4 by the heat generated by the light source 2 is radiated through the metal radiator plate 6. The back surface of the housing 10 that covers the radiator plate 6 and the left and right ends thereof is covered with a back cover RC. L-shaped steps RCa and RCb are formed on the left and right sides of the left and right ends of the back cover RC to cover the housing 10 as well.

In the illumination unit UT having such a configuration, the liquid crystal display panel 1 is disposed on the irradiation surface side (upward in the drawing) of the illumination unit UT, and the back cover RC and the front frame FC are attached to the liquid crystal display UT. Device L. The front side frame FC is a frame that holds the liquid crystal display panel 1 and other components so as to include the liquid crystal display panel 1 from the front side (front side). In the liquid crystal display device L, the light emitted from the light source 2 is directly or condensed by the reflector 4 and guided to the light guide plate 3, and is evenly transmitted to the entire back surface of the liquid crystal display panel 1, so that the liquid crystal display L Display surface 1a of panel 1
The characters and images projected on the screen become visible.

[0009]

However, in the liquid crystal display device L of the above-mentioned conventional configuration, the heat generated by the light source 2 which emits light is transmitted to the metal heat radiating plate 6 via the reflector 4, but the reflector 4 is made of aluminum or the like. Composed of metal,
Since the reflective surface is coated with a synthetic resin, there has been a problem that the contact with the metal heat radiating plate 6 passes through the resin and the heat radiating effect is reduced. When the temperature around the light source 2 rises, there is also a problem that the life of the light source 2 is shortened.

Further, in the above-described conventional configuration, when the light guide plate 3 becomes larger than the reflection sheet 5 due to manufacturing variations, a portion of the light guide plate 3 protruding from the reflection sheet 5 (reference numeral Z in FIG. 3). Position) when viewed from the display surface 1a of the liquid crystal display panel 1 has a problem that it looks brighter than other display portions. That is, when the light guide plate 3 is slightly larger than the reflection sheet 5, the metal heat sink 6 is located below the light guide plate 3.
When viewed from the display surface 1a of the liquid crystal display panel 1, it looks brighter than other display portions.

Therefore, an object of the present invention is to efficiently dissipate the heat transmitted to the reflector by the heat generated by the light source through the heat radiating plate, and to prevent the light guide plate from being larger than the reflecting sheet due to manufacturing variations. An object of the present invention is to provide a lighting unit capable of maintaining display quality of a display surface of a liquid crystal display panel and a liquid crystal display device using the same.

[0012]

In order to solve the above-mentioned problems, a lighting unit according to claim 1 of the present invention comprises a light source,
A light guide plate for guiding light from the light source, a reflector made of metal disposed at least to surround the light source and reflecting light in the direction of the light guide plate, at least a back surface of which is made of metal, and a reflection sheet for reflecting light incident on the light guide plate And a metal radiator plate for covering the back surface of the reflection sheet and dissipating the heat transmitted to the reflector by the heat generated by the light source, wherein one end side of the reflector is a reflection sheet from the front side. The rear side is sandwiched by a metal heat sink.

According to this invention, since the reflector side of the metal heat sink contacts the metal surface on the back surface of the reflector, the heat transmitted from the light source to the reflector is efficiently transferred by the metal-to-metal contact. Is performed to improve the heat radiation effect. Also, even if the light guide plate becomes larger than the reflection sheet due to manufacturing variations, the back side of the light guide plate becomes the reflection surface of the reflector,
The conventional display does not cause uneven brightness on the display surface.

A lighting unit according to a second aspect of the present invention comprises:
On the premise of the invention according to claim 1, a back cover that covers the back surface of the heat sink is provided, and one end side of the reflector of the back cover faces the heat sink corresponding to a portion sandwiched between the reflective sheet and the heat sink. It is characterized in that a convex part which becomes partially convex is formed.

According to the present invention, when the back cover on which the convex portion is formed is attached, the adhesion ratio of the portion where one end side of the heat sink and the reflector is sandwiched between the reflection sheet and the heat sink can be improved. In addition, the heat transfer coefficient is increased and the heat radiation effect is further increased, and it is possible to prevent dust from entering from outside into the gap between the back cover and the heat radiation plate.

According to a third aspect of the present invention, there is provided a liquid crystal display device using the illumination unit according to the first aspect or the second aspect, and the illumination unit is disposed on the illumination surface side of the illumination unit. A liquid crystal display panel.

According to the present invention, by changing the arrangement of the heat radiating plate, the heat transmitted from the light source to the reflector can be efficiently released, and the display surface can be prevented from having uneven brightness. The liquid crystal display device uses an inexpensive and highly reliable lighting unit.

[0018]

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

(First Embodiment) In this embodiment, as shown in FIG. 1, a light source 2, a flat light guide plate 3 for transmitting light from the light source 2, and a light guide plate 3 surrounding the light source 2 are provided. An illumination unit UT includes a reflector 4 disposed to reflect light in the direction of the light guide plate 3 and a housing 10 disposed to surround the reflector 4, and a liquid crystal display device L using the same.
The light source 2 is a fluorescent discharge tube 2 that emits light when driven by a high-frequency alternating current (40 to 100 kHz). The light source 2 of the present embodiment is provided with two lamps on each of the left and right sides of the light guide plate 3, one light source, one light source or a plurality of light sources on one side of the light guide plate 3, and , One of which is arranged in an L-shape on two of the four sides of the light guide plate 3 (referred to as an “L-shaped fluorescent discharge tube”), etc., all of which are called an edge light type.

The light guide plate 3 is made of a material such as acrylic having an optimum optical characteristic represented by a transmittance and a refractive index necessary for light transmission. The light guide plate 3 is provided with a dot pattern or a groove pattern (not shown) whose shape is changed according to the distance from the light source 2 on the back surface.

The reflector 4 reflects the light of the fluorescent discharge tube 2 and makes the light incident on the incident side surface 3a of the light guide plate 3 efficiently. The reflector 4 has a high reflectivity such as a white resin film, silver or aluminum. Is bent in a U-shaped cross section or a U-shaped cross section so as to surround the fluorescent discharge tube 2.

The reflection sheet 5 has a role of returning the light going out from the back surface of the light guide plate 3 back into the light guide plate 3 and increasing the illuminating light to be emitted, and is disposed along the back surface of the light guide plate 3. ing. The reflection sheet 5 is made of a white resin film having a high reflectance. In some cases, one side of the reflection sheet 5 is bent into a U-shape or a horizontal U-shape so as to surround the light source 2 to form a reflector 4 integrated with the reflection sheet 5.

The housing 10 is arranged close to the side surface of the reflector 4 so as to surround it from above. Housing 1
Reference numeral 0 serves as a holder for the reflector and also holds the liquid crystal display panel 1, the light source 2, and the light guide plate 3. A gap 7a is formed between the housing 10 and a metal front frame FC described later. The housing 10 is made of, for example, a polycarbonate resin.

The heat radiating plate 6 controls the heat generation of the light source 2 by the reflector 4.
, And is made of a metal plate, and covers the reflection sheet 5 along the back surface of the reflection sheet 5. The lower end of the reflector 4 formed in a substantially U-shape is in contact with the left and right ends of the rear surface of the heat sink 6 from the rear surface. Therefore, the heat transmitted to the reflector 4 by the heat generated by the light source 2 is radiated through the metal radiator plate 6. The back surface of the housing 10 that covers the radiator plate 6 and the left and right ends thereof is covered with a back cover RC. L-shaped steps RCa and RCb are formed on the left and right sides of the left and right ends of the back cover RC to cover the housing 10 as well.

In such a lighting unit UT, the liquid crystal display panel 1 is disposed on the irradiation surface side, and a back cover RC and a metal front frame FC are attached.
The liquid crystal display device L is obtained. The liquid crystal display panel 1 displays characters and images. A pair of transparent substrates on which display electrodes are laid face each other at an appropriate interval, and a liquid crystal material is sealed at the interval with a sealing material around the transparent substrate. A liquid crystal display panel 1 configured to be stopped, a plurality of driving circuits arranged around the liquid crystal display panel 1 for displaying the liquid crystal display panel 1, a substrate on which the driving circuit is mounted, and the like. Is done.

In the liquid crystal display device L in which the liquid crystal display panel 1 is mounted on the irradiation surface side (upper side in the drawing) of the illumination unit UT, the light emitted from the light source 2 is collected directly or by the reflector 4. By being guided to the light guide plate 3 and being evenly transmitted to the entire back surface of the liquid crystal display panel 1,
The characters and images projected on the display surface 1a of the liquid crystal display panel 1 become visible.

Therefore, in the liquid crystal display device L of the present embodiment, the heat transmitted to the reflector 4 by the heat generated by the light source 2 is efficiently radiated through the heat radiating plate 6. That is, as shown in FIG. 2, since the metal surface 4b on the back surface side of the reflector 4 and the metal radiator plate 6 are in contact with each other, efficient heat transfer is performed and the heat radiation effect is achieved. Will be improved. It should be noted that such a configuration can be easily assembled simply by changing the arrangement configuration using conventional components.

Further, as shown in FIG. 3, even when the light guide plate 3 is larger than the reflection sheet 5 (even when the position shift Z occurs), the reflection surface of the reflector 4 is provided on the back surface side of the light guide plate 3. Since the reflection surface (4a) coated with the resin is disposed, the light guide plate 3 does not partially shine, and the quality without unevenness in brightness can be secured even when viewed from the display surface.

(Second Embodiment) In this embodiment, as shown in FIG. 4, on the premise of the first embodiment, a convex portion RC1 is formed on the back cover RC. The convex portion RC1 is provided to increase the close contact with the metal heat radiating plate 6, and the heat radiating plate 6 side of the back cover RC is provided in a convex shape. That is, the back cover RC
Aluminum (AL) or galvanized steel sheet (SECC) is often used as the material of the reflector. A plurality of parts are arranged at the places corresponding to the parts indicated by.

Therefore, the convex portion RC1 of the back cover RC is provided.
As a result, the heat radiating plate 6 is pressed to the front side, and the adhesion ratio between the heat radiating plate 6 and the reflector 4 is improved, so that the transmissivity is increased and the heat radiation effect is further enhanced. Further, conventionally, the metal heat radiating plate 6 and the back cover RC are superimposed, but dust may enter the gap of the superimposition.
In the lighting unit UT and the liquid crystal display device L of the present embodiment, the intrusion of dust can be prevented by the convex portion RC1 of the back cover RC.

As described above, in each embodiment, the straight tube type light source 2
Has been described using two lamps, but one lamp may be used instead of two straight tube lamps. In addition, the light source is arranged on both sides of the light guide plate 3, but the present invention is applicable to an edge light type in which a power source is arranged on one side of the light guide plate 3, a type in which the light source is arranged in an L shape, and the like. It is generally applicable to the edge light method.

[0032]

According to the lighting unit of the present invention and the liquid crystal display device using the same, since the reflector side of the metal radiator plate is in contact with the metal surface on the back surface of the reflector, the heat transmitted from the light source to the reflector is reduced. , Due to metal-metal contact,
Efficient heat transfer is performed, the heat radiation effect is improved, and it is possible to prevent adverse effects due to heat generation, such as a decrease in luminance in a liquid crystal display device using this lighting unit, and to shorten the life of the light source. It can be longer. Also, even if the light guide plate becomes larger than the reflective sheet due to manufacturing variations, the back side of the light guide plate becomes the reflective surface of the reflector, thus preventing the conventional display surface from causing uneven brightness. It becomes possible to do.

[0033]

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device using a lighting unit according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the liquid crystal display device according to the first embodiment.

FIG. 3 is a cross-sectional view showing a positional deviation between the light guide plate and the reflection sheet according to the first embodiment.

FIG. 4 is a sectional view of a liquid crystal display device using a lighting unit according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Light source 3 Light guide plate 4 Reflector, 4a reflection surface, 4b metal surface, 5 reflection sheet, 6 heat sink, 10 housing, RC back cover, RC1 convex part, FC front side frame

Claims (3)

[Claims]
1. A light source, a light guide plate for guiding light from the light source, a reflector disposed to surround the light source and made of metal at least on the back side for reflecting light in the direction of the light guide plate, In a lighting unit including a reflecting sheet that reflects the light that has been emitted, and a metal radiator plate that covers the back surface of the reflecting sheet and radiates the heat transmitted to the reflector by the heat generated by the light source, one end of the reflector is A lighting unit characterized in that a reflection sheet is sandwiched from a front side thereof and a metal heat dissipation plate is sandwiched on a back side thereof.
2. A back cover for covering the back surface of the heat sink, wherein one end of the reflector of the back cover is partially convex toward the heat sink corresponding to a portion sandwiched between the reflection sheet and the heat sink. The lighting unit according to claim 1, wherein a convex portion is formed.
3. A liquid crystal display device comprising: the illumination unit according to claim 1; and a liquid crystal panel disposed on an illumination surface side of the illumination unit.
JP2001077629A 2001-03-19 2001-03-19 Lighting unit, and liquid crystal display device using the same Pending JP2002279813A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001077629A JP2002279813A (en) 2001-03-19 2001-03-19 Lighting unit, and liquid crystal display device using the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2001077629A JP2002279813A (en) 2001-03-19 2001-03-19 Lighting unit, and liquid crystal display device using the same

Publications (1)

Publication Number Publication Date
JP2002279813A true JP2002279813A (en) 2002-09-27

Family

ID=18934356

Family Applications (1)

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JP2001077629A Pending JP2002279813A (en) 2001-03-19 2001-03-19 Lighting unit, and liquid crystal display device using the same

Country Status (1)

Country Link
JP (1) JP2002279813A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008153163A (en) * 2006-12-20 2008-07-03 Victor Co Of Japan Ltd Planar light source, liquid crystal display device, and image display device

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0651293A (en) * 1992-08-03 1994-02-25 Sharp Corp Liquid crystal display device
JPH0864021A (en) * 1994-08-23 1996-03-08 Sanyo Electric Co Ltd Lighting system and liquid crystal display device employing the lighting device
JPH09218404A (en) * 1996-02-09 1997-08-19 Sanyo Electric Co Ltd Liquid crystal module
JPH10106329A (en) * 1996-09-30 1998-04-24 Sony Corp Back light device
JPH11295733A (en) * 1998-04-10 1999-10-29 Denso Corp Surface light source for liquid crystal display device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0651293A (en) * 1992-08-03 1994-02-25 Sharp Corp Liquid crystal display device
JPH0864021A (en) * 1994-08-23 1996-03-08 Sanyo Electric Co Ltd Lighting system and liquid crystal display device employing the lighting device
JPH09218404A (en) * 1996-02-09 1997-08-19 Sanyo Electric Co Ltd Liquid crystal module
JPH10106329A (en) * 1996-09-30 1998-04-24 Sony Corp Back light device
JPH11295733A (en) * 1998-04-10 1999-10-29 Denso Corp Surface light source for liquid crystal display device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008153163A (en) * 2006-12-20 2008-07-03 Victor Co Of Japan Ltd Planar light source, liquid crystal display device, and image display device
JP4650743B2 (en) * 2006-12-20 2011-03-16 日本ビクター株式会社 Surface light source device, liquid crystal display device, and image display device

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