JP2003036717A - Surface light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface light source with high radiation of heat that can securely scatter heat generated in a light emitting substance. SOLUTION: This surface light source is equipped with a mounting substrate 6 that mounts a light emitting substance 11, a light guide plate 2 that guides light emitted from the light emitting substance 11 and outputs it, a frame 3 that supports the light guide plate 2, reflecting sheets 19A, 19B that are arranged so as to cover the light emitting substance 11 and reflect light emitted from the light emitting substance 11 and guide it into the light guide plate 2, and a metallic film 18 adhering to the reflecting sheets 19A, 19B. Since the metallic film 18 is brought into contact with the mounting substrate 6 and the frame 3, by transferring the heat generated in the light emitting substance 11 to the frame 3 via the metallic film 18, the heat generated in the light emitting substance can securely be scattered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light source, and is suitable for application to, for example, a backlight of a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, liquid crystal display panels have been widely used as display devices for portable electronic equipment such as mobile phones. Since such a liquid crystal panel is not a self-luminous device, a means for illuminating it is necessary. For example, in a reflective liquid crystal display device, a reflector is provided on the back side of the liquid crystal panel, and external light incident from the surface of the liquid crystal panel is reflected by the reflector to illuminate it. Further, in the transmissive liquid crystal display device, a backlight is arranged on the back side of the liquid crystal panel, and the liquid crystal panel is illuminated by the backlight.

FIG. 8 shows a backlight 1 using a cold-cathode tube as a light source. The light guide plate 2 has a wedge-shaped cross section, a frame 3 surrounding the peripheral edge of the light guide plate 2, and a thick light guide plate 2. And a light source unit 5 provided at the side end,
Light emitted from the cold cathode tubes 4 in the light source section 5 by the drive current supplied through the flexible substrate 6 is guided to the light guide plate 2.
The light is diffused evenly and is emitted from the emission surface 2A of the light guide plate 2.

As shown in FIG. 9, in the light source section 5, a housing 7 formed by pressing a metal plate surrounds the periphery of the cold cathode fluorescent lamp 4. The housing 7 protects the cold cathode fluorescent lamp 4 and cools it. The light emitted from the cathode tube 4 is reflected on the inner surface of the housing 7 and efficiently enters the light guide plate 2. A reflection sheet 8 is attached to the back surface of the light guide plate 2 so that the light incident from the cold cathode tubes 4 is reflected and uniformly emitted from the emission surface 2A.

In the backlight 1 using such a cold cathode tube, in order to improve the working tolerance when the housing 7 is processed by sheet metal and the workability when the cold cathode tube 4 is inserted into the housing 7, The internal size of 7 must be selected to be somewhat larger than that of the cold cathode tube 4, which increases the outer size of the light source unit 5.

On the other hand, FIG. 10 shows an LED (Li
ght Emitting Diode: a backlight 10 using a light emitting diode, which is composed of a light guide plate 2, a frame 3, and a light source unit 12 having a plurality of LEDs 11 built therein, and is driven by a drive current supplied through a flexible substrate 6. LE
The light emitted from D11 is uniformly diffused by the light guide plate 2 and emitted from the emission surface 2A.

As shown in FIG. 11, in the backlight 10, the reflection sheet 8 is attached so as to integrally surround the entire back surface of the light guide plate 2, the lower surface to the upper surface of the LED 11, and the thick side end portion of the upper surface of the light guide plate 2. The light emitted from the LED 11 is efficiently reflected by the reflection sheet 8.

In the backlight 10 using such an LED, the housing 7 used in the backlight 1 using a cold cathode tube is not necessary, and since the LED has a smaller external dimension than the cold cathode tube, the light source section 12 is provided. The external dimensions of can be reduced.

[0009]

Here, when an LED is used as a light source of a backlight, the resin encapsulating the LED changes color when the temperature of the LED rises, which causes a decrease in the light amount of the LED. There is a problem that the emission color changes. In order to prevent the discoloration of the sealing resin, L
It is necessary to control the amount of current flowing through the ED to be equal to or less than a predetermined rated current, and in this case as well, there is a problem that the light amount of the LED is reduced and the brightness of the backlight is reduced.

The present invention has been made in consideration of the above points, and an object thereof is to propose a planar light source having a high heat dissipation property, which can surely dissipate the heat generated by the light emitting body.

[0011]

In order to solve such a problem, in the present invention, a mounting substrate on which a light emitter is mounted, a light guide plate for guiding and emitting the light emitted by the light emitter, and a light guide plate are supported. It is arranged so as to cover the frame and the luminous body,
A reflection sheet that reflects the light emitted by the light-emitting body and guides the light to the light guide plate and a metal film attached to the reflection sheet are provided, and the metal film is brought into contact with the mounting substrate and the frame.

By transmitting the heat generated by the light emitting body to the frame through the metal film, the heat generated by the light emitting body can be surely dissipated.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, in which parts corresponding to those in FIG. 10 are designated by the same reference numerals, numeral 15 indicates the backlight according to the present invention as a whole, which includes the light guide plate 2, the frame 3, and a plurality of LEs.
A light source unit 16 having a built-in D11 is provided so that the light emitted from the LED 11 as a light emitting body is uniformly diffused by the light guide plate 2 by the drive current supplied through the flexible substrate 6 and emitted from the emission surface 2A. Has been done.

As shown in FIG. 2, in the backlight 15, the entire back surface of the light guide plate 2, the lower surface to the upper surface of the LED 11, and the thick side end portion of the upper surface of the light guide plate 2 are continuously surrounded so as to surround the heat transfer reflection sheet. 17 is attached.

FIG. 3 shows a heat transfer reflection sheet 17, which is constituted by laminating reflection sheets 19A and 19B made of a white polyethylene film on a metal film 18 made of a soft aluminum film material having a good thermal conductivity. .

The reflection sheet 19A has a substantially rectangular shape, and the short side thereof and the short side of the metal film 18 are selected to have the same size, and the short side of the reflection sheet 19B and one short side of the metal film 18 coincide with each other. Are pasted together in this way. Then, as shown in FIG. 2, the long side of the reflection sheet 19B is selected to have a length capable of covering the entire back surface of the light guide plate 2 and the bottom surface of the LED 11.

On the other hand, the reflection sheet 19B is in the form of a long strip, the long side of which is selected to have the same dimension as the short side of the metal film 18, and the long side of the reflection sheet 19B and the other short side of the metal film 18 coincide with each other. It is pasted as it is. Then, as shown in FIG. 2, the short side of the reflection sheet 19B is selected to have a length capable of covering the upper surface of the LED 11.

Therefore, in the heat transfer reflection sheet 17,
Metal film 1 between the reflection sheets 19A and 19B
The exposed portion of 8 directly contacts the flexible substrate 6 on which the LED 11 is mounted (FIG. 2). As a result, in the light source section 16, the heat generated from the LED 11 is conducted to the metal film 18 via the flexible substrate 6.

Further, a ridge-shaped protrusion 3A is provided on the lower surface of the frame 3 on the light source 16 side, and the frame 3 and the metal film 18 are brought into contact with each other via the protrusion 3A.

Thus, in the backlight 15, L
The heat generated by the ED 11 is conducted to the frame 3 through the flexible substrate 6 and the metal film 18 and radiated,
It is designed to prevent heating of D11.

Next, a method of assembling the backlight 15 will be described in detail with reference to FIGS. First, as shown in FIG. 4, the light guide plate 2 is attached to the reflection sheet 19 of the heat transfer reflection sheet 17.
Attach to A using thin transparent double-sided tape. At this time, the thin side end of the light guide plate 2 and the short side of the heat transfer reflection sheet 17 on the reflection sheet 19A side are aligned.

Then, as shown in FIG. 5, the LED unit 22 including the flexible substrate 6 and the LEDs 11 mounted on the flexible substrate 6 is attached to the exposed portion of the reflection sheet 19A. At this time, the light emitting surface of the LED 11 is brought into close contact with the thick side end surface of the light guide plate 2, and the end portion of the flexible substrate 6 is inserted into the opening 21 of the heat transfer reflection sheet 17.

Then, as shown in FIG. 6, the reflection sheet 19B side of the heat transfer reflection sheet 17 is wound around the LED unit 22, and the LED unit 22 is fixed to the light guide plate 2 by the heat transfer reflection sheet 17 and the light source section 16 is provided. (FIG. 2). At this time, the flexible substrate 6 and the exposed portion of the metal film 18 are in contact with each other, and the upper surface of the LED 11 and the reflection sheet 19B are in contact with each other. Then, as shown in FIG. 7, the light guide plate 2 integrated with the light source unit 16 is inserted into the frame 3 to complete the backlight 15.

In the above construction, the metal film 18 and the reflection sheets 19A and 19B are attached to each other to form the heat transfer reflection sheet 17, and the LED unit 2 is formed from the rear surface of the light guide plate 2.
2, and the heat transfer reflection sheet 17 is attached so as to continuously surround up to the thick side end of the upper surface of the light guide plate 2.

The metal film 18 and the frame 3 are brought into contact with each other so that the heat generated from the LED 11 is conducted to the frame 3 through the metal film 18 and radiated, so that the heat generated by the LED 11 is surely radiated. Therefore, the deterioration of the LED 11 can be prevented.

Further, an exposed portion of the metal film 18 is provided between the reflection sheets 19A and 19B, and the metal film 1 is exposed.
8 and the flexible substrate 6 are in direct contact with each other, the thermal resistance between the LED 11 and the metal film 18 is reduced, and the heat generated from the LED 11 can be more efficiently conducted to the frame 3 to be radiated. .

In the above embodiment, the light guide plate 2 is attached to the reflection sheet 19A using a thin transparent double-sided tape, but the present invention is not limited to this, and it may be attached using an adhesive material or the like. You can

Further, in the above-mentioned embodiment, the metal film 18 is formed over the entire surfaces of the reflection sheets 19A and 19B.
However, it suffices that the heat generated from the LED 11 can be conducted to the frame 3, and for example, the metal film 1 is limited to between the flexible substrate 6 and the frame 3.
8 may be attached.

Further, in the above embodiment, LE
Although the flexible substrate 6 on which D11 is mounted and the metal film 18 are brought into contact with each other so that the heat generated by the LED 11 is conducted to the metal film 18, the present invention is not limited to this.
The heat generated may be conducted to the metal film 18 by directly contacting the LED 11 and the metal film 18.

[0031]

As described above, according to the present invention, the mounting substrate on which the light emitting body is mounted, the light guide plate for guiding and emitting the light emitted by the light emitting body, the frame for supporting the light guide plate, and the light emitting plate A reflective sheet, which is arranged so as to cover the body and reflects the light emitted by the light-emitting body and guides the light to the light guide plate, and a metal film attached to the reflective sheet are provided so that the metal film contacts the mounting substrate and the frame. By doing so, the heat generated by the light emitting body can be transferred to the frame via the metal film, and the heat generated by the light emitting body can be surely dissipated.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an overall configuration of a backlight according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a light source unit.

FIG. 3 is a schematic perspective view showing a configuration of a heat transfer reflection sheet.

FIG. 4 is a schematic perspective view showing attachment of a heat transfer reflection sheet and a light guide plate.

FIG. 5 is a schematic perspective view showing attachment of an LED unit.

FIG. 6 is a schematic perspective view showing winding of a heat transfer reflection sheet.

FIG. 7 is a schematic perspective view showing the attachment of the frame.

FIG. 8 is a schematic perspective view showing an overall configuration of a backlight using a cold cathode tube.

FIG. 9 is a schematic diagram showing a configuration of a light source section using a cold cathode tube.

FIG. 10 is a schematic perspective view showing an overall configuration of a backlight using LEDs.

FIG. 11 is a schematic diagram showing a configuration of a light source section using LEDs.

[Explanation of symbols]

1, 10, 15 ... Backlight, 2 ... Light guide plate, 3 ...
... Frame, 4 ... Cold cathode tubes, 5, 12, 16 ... Light source section, 6 ... Flexible substrate, 7 ... Housing, 8,
19A, 19B ... Reflective film, 11 ... LED, 1
7 ... Heat transfer reflection sheet, 18 ... Metal film, 21 ...
…Aperture.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/00 336 G09F 9/00 336J // F21Y 101: 02 F21Y 101: 02 103: 00 103: 00 ( 72) Inventor Isao Yoshino 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Kazuo Hashimoto 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Invention Toshiaki Igawagawa 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo F-Term of Sony Corporation (reference) 2H038 AA55 BA06 2H091 FA14Z FA23Z FA45Z FB08 LA04 LA16 3K014 LA01 LA04 LB02 5G435 AA12 BB12 BB15 EE27 FF03 FF08 GG23 GG15

Claims (2)

[Claims] 1. A mounting substrate on which a light emitting body is mounted, a light guide plate for guiding and emitting the light emitted by the light emitting body, a frame for supporting the light guide plate, and a light emitting plate arranged so as to cover the light emitting body. A reflection sheet that reflects the light emitted by the light-emitting body and guides the light to the light guide plate; and a metal film attached to the reflection sheet, the metal film contacting the mounting substrate and the frame, and emitting the light. A planar light source, which transfers heat generated by a body to the frame. 2. The planar light source according to claim 1, wherein the light emitter is a light emitting diode.