JP2008216406A5 - - Google Patents

Description

Liquid crystal display

The present invention relates to an image using a liquid crystal panel in a notebook personal computer (hereinafter referred to as notebook PC), relates to a liquid crystal display device for displaying characters or the like, the heat of the light source is efficiently dissipated particularly configure this, and the surface light source The present invention relates to a heat dissipation structure for protecting the unit.

  In recent years, an increasing number of white light emitting diodes (LEDs) are used as backlights of liquid crystal display devices using liquid crystal panels. The backlight illuminates the LCD panel from the back, and this technology is used for thin LCD panels.

  In recent years, white LEDs having a luminous efficiency exceeding 60 lm / W have appeared one after another, and the light use efficiency in practical use has been reversed from that of fluorescent lamps. As a result, the practical use of white LEDs instead of fluorescent lamps has rapidly increased.

The backlight according to the white LED has a merit that said power supply circuit, compared to the backlight by a fluorescent lamp is simplified, a backlight of a liquid crystal display device miniaturization, such as a laptop towards white LED is proposition Suitable for.
White LEDs have a trade-off relationship between the luminance and deterioration due to heat generation, and therefore, heat dissipation measures are important. Patent Document 1 shows an LED used as a backlight in which heat is radiated to the outside from an aluminum heat sink through a shield cover. Patent Document 2 discloses a convex portion and a concave portion on a sheet metal. There is shown a liquid crystal display device having a heat dissipation structure that is provided and has a concave portion in contact with a housing.
JP 2006-208722 A JP 2005-121897 A

However, the above-described conventional heat dissipation structure is not sufficient for maintaining the high brightness of the white LED and suppressing deterioration due to heat generation, and more efficient countermeasures have been demanded.

The present invention solves the above-mentioned conventional problems, not only to increase the brightness and simplify the structure by adopting a white LED in the liquid crystal backlight, but also to release the heat generated from the white LED well, And it aims at providing the thermal radiation structure which protects a surface light source unit .

The present invention is a liquid crystal display device in which a liquid crystal panel, a surface light source unit having an LED (Light Emitting Diode) as a light source, and a heat dissipation structure that dissipates heat generated from the LED are disposed in a housing, The surface light source unit has a light guide plate that guides the light of the LED, a reflection sheet, and an optical sheet that controls light output, the heat dissipation structure is made of a sheet metal with high thermal conductivity, the heat dissipation structure includes a base portion, A surface light source unit having a heat absorption part that is thermally coupled to the LED, and a raised part that is raised from the base part via a rising part, and the heat dissipation structure is arranged in the case and the case; Between the surface light source unit and the heat absorption part of the heat dissipation structure in a state of being thermally coupled to the LED. The heat generated from the ED can be efficiently released by the heat dissipation structure, and the surface light source unit can be protected from external pressure applied from the outside of the housing by the heat dissipation structure.

As described above, the present invention is in a state where the raised portion of the heat dissipation structure is not in contact with the surface light source unit between the housing and the surface light source unit arranged in the housing, and The heat absorption part of the heat dissipation structure is disposed in a state of being thermally coupled to the LED. According to this, heat generated from the LED employed in the surface light source unit constituting the liquid crystal backlight is transmitted from the heat dissipation structure. In addition to being able to emit efficiently, the heat dissipation efficiency by the heat sink further increases due to the convection of air generated in the space of the gap formed between the raised part of the heat dissipation structure and the surface light source unit, The heat dissipation structure also has an excellent effect of protecting the surface light source unit against external pressure applied from outside the housing.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1A is a perspective view of a notebook computer according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view of the display section shown in FIG.

  In FIG. 1A, 10 is a notebook personal computer, 11 is a liquid crystal display device that is a display unit for displaying images, characters, and the like, and 12 is a main body unit that houses an information processing circuit such as a CPU (central processing unit). .

In FIG. 1B, the display unit 11 generally includes a light transmission type liquid crystal panel 13 in which a liquid crystal layer is held between a pair of glass substrates, and a surface light source unit 14 disposed on the back surface of the liquid crystal panel 13. Have Then, the liquid crystal panel 13 is placed on a resin frame 15 having a substantially rectangular frame shape , and the resin frame 15 is attached to and accommodated in the housing 16 in a state of being superimposed on the liquid crystal panel 13. Accordingly, the liquid crystal panel 13 is held in a state where the periphery is held between the resin frame 15 and the housing 16.

Usually, the surface light source unit 14 includes a light guide plate 141, and a white LED142 a light source provided to face the one side edge of the light guide plate 141. Furthermore, purposes diffusion sheet on the light emitting side of the light guide plate 141 for controlling the light output characteristics, the optical sheet 143 is installed comprising a plurality of sheets such as a prism sheet, and reflection on the side opposite to the light exit surface sheet 144 is provided.

The light guide plate 141, the optical sheet 143, the reflection sheet 144, and the white LED 142 that is a light source that constitute the surface light source unit 14 are mounted on the resin frame 15. That is, the display unit 11 is a liquid crystal panel 13 from the light emitting side in order, the resin frame 15, the optical sheets (diffusion sheet, prism sheet, etc.) 143, a light guide plate 141, superposed in this order of the reflection sheet 144, one side of the light guide plate 141 A white LED 142 is arranged at the end . The liquid crystal panel 13 is held in a state of being held between the casing 16 and the resin frame 15 as described above.

  Reference numeral 17 denotes a heat radiating plate, one end of which is thermally coupled to a white LED 142 that is a light source constituting the surface light source unit 14. The heat radiating plate 17 is preferably made of a sheet metal material that has high thermal conductivity and high strength but is easy to be rolled and rolled.

In addition, a control circuit board including a liquid crystal panel control circuit that processes a video signal and displays an image on the liquid crystal panel 13, an LED control circuit that supplies light to the white LED 142 to control light emission, and the like is also included in the housing 16 of the display unit 11. Although not shown in the figure.

  Further, in the present embodiment, the casing 16 is molded from a light metal material such as magnesium or aluminum alloy from the viewpoint of strength and weight required for the notebook computer.

  FIG. 2 is a perspective view of a heat sink used in the liquid crystal display device of the present invention.

In the heat sink 17 shown in FIG. 2, A is a base portion that supports the entire heat sink, B is a heat absorbing portion that is in thermal contact with the white LED, C is a raised portion that is raised by molding with respect to the base portion A, D Is formed from a support part that is supported by the casing 16 by jumping up substantially vertically from the raised part C.

  The operation of the liquid crystal display device configured as described above will be described with reference to FIGS.

The white LED 142 which is the light source of the surface light source unit 14 constituting the backlight has come to be used for various light sources because the light utilization efficiency exceeds that of the fluorescent lamp, but all the power supplied to the white LED element is It is not converted into light energy, but rather the proportion of power energy converted into light energy is lower than the rate converted into heat energy. The heat energy by this has a trade-off relationship with the light emission luminance of the LED, and if the heat generated from the white LED 142 is not eliminated by using a heat dissipation means with good heat dissipation efficiency , not only the light emission luminance is lowered but also the life of the white LED 142 is increased. It will also shorten.

Therefore, in the liquid crystal display device of the present invention, the heat radiating plate 17 ( heat radiating structure ) is disposed between the housing 16 and the surface light source unit 14 as shown in FIG. It is arranged in the gap. The heat radiating plate 17 is thermally coupled to the white LED 142 by the heat absorbing portion B, and the support portion D is mechanically coupled to the housing 16 and is also thermally coupled. .

Here, when the casing 16 receives external pressure from the back side, the heat radiating plate 17 mechanically coupled to the casing 16 further receives the external pressure, and the external pressure is applied to the surface light source unit 14 via the heat radiating plate 17. The light guide plate 141, the optical sheet 143, and the reflection sheet 144 that constitute the liquid crystal panel 13 are deformed, causing display luminance unevenness and color unevenness of the liquid crystal panel 13.

Further, when the heat radiating plate 17 comes into contact with the surface light source unit 14 other than the white LED 142 , the heat generated from the white LED 142 causes the light guide plate 141, the optical sheet 143, and the reflection sheet 144 made of a resin material to be thermally deformed or long. If contact for a period continues, the material of each sheet material will also change.

  Actually, in FIG. 1B, when the light guide plate 141 and the optical sheet 143 in the display area for displaying images, characters, etc. are subjected to mechanical pressure such as external pressure at one point, light is transmitted, or The material to be reflected causes white turbidity deterioration, and the display image causes white spotted pattern and wavy display unevenness.

For this reason, the heat sink 17 of the present invention is formed by molding as shown in FIG. 2 to form a raised portion C having no mechanical contact between the heat sink 17 and the surface light source unit 14 excluding the white LED 142. . The rising portion C ′ of the raised portion C is molded with a sharp when the heat radiating plate 17 is made of metal sheet metal, and the rising portion C ′ is arranged outside the display area which is an effective display area of the image shown in FIG. It is molded into the shape that will be used.

By doing in this way, even if external pressure is received from the back surface of the housing 16, the external pressure is transmitted in the order of the housing 16 → the support portion D → the raised portion C → the base portion A formed in the peripheral portion of the radiator plate 17, Since it is dispersed, the external pressure applied to the light guide plate 141, the optical sheet 143, and the reflection sheet 144 of the surface light source unit 14 can be suppressed, and the rising portion C ′ forming the raised portion C and finally receiving the external pressure. Since the base portion A is disposed outside the display area, image quality deterioration due to deformation of the surface light source unit 14 can be prevented.

Further , by forming a gap between the raised portion C of the heat radiating plate 17 and the surface light source unit 14, air convection is easily generated in this space, and the heat radiating efficiency of the heat radiating plate 17 is further increased. Have.

As described above, according to the present embodiment, when a white LED is used for the liquid crystal backlight , the heat generated from the white LED is efficiently released by the heat dissipation structure (heat dissipation plate 17) of the present invention. In addition, the heat dissipation structure of the present invention has the function of protecting the surface light source unit against external pressure applied from the outside of the housing.

  Note that a control circuit board including a liquid crystal panel control circuit that processes a video signal of a liquid crystal display device that is not shown and displays an image on the liquid crystal panel, an LED control circuit that supplies power to a white LED to control light emission, and the like If it arrange | positions using the gap | interval of the protruding part C of the unit 14 and the heat sink 17, it can contribute to size reduction of the display part 11 of a notebook personal computer.

  Moreover, although white LED was demonstrated to the example as a light source of a backlight, it cannot be overemphasized that the white light source by the synthetic light which consists of red, blue, and green LED may be sufficient.

The liquid crystal display device according to the present invention, not the heat generated from the white LED employing the LCD backlight only can be efficiently released, the surface against external pressure applied from outside the housing of the liquid crystal display device It has an effect of protecting the light source unit and is useful as a liquid crystal display device in a notebook personal computer .

1 shows Embodiment 1 of the present invention, where (a) is a perspective view of a notebook computer, and (b) is a cross-sectional view taken along a broken line illustrating a display unit. The perspective view of the heat sink used for the liquid crystal display device of this invention

10 Notebook PC 11 Display (Liquid Crystal Display)
12 Notebook PC Main Body 13 Liquid Crystal Panel 14 Surface Light Source Unit 15 Resin Frame 16 Display Unit Housing 17 Heat Dissipation Plate (Heat Dissipation Structure)
141 Light guide plate 142 White LED
143 Optical sheet 144 Reflective sheet A Base part B Heat absorption part C Raised part D Support part

Claims (1)

A liquid crystal display device in which a liquid crystal panel, a surface light source unit having an LED (Light Emitting Diode) as a light source, and a heat dissipation structure for radiating heat generated from the LED are disposed in a housing
The surface light source unit has a light guide plate that guides the light of the LED, a reflection sheet, and an optical sheet that controls light emission,
The heat dissipation structure is made of a sheet metal having a high thermal conductivity, and the heat dissipation structure includes a base portion, a heat absorption portion that is thermally coupled to the LED, and a raised portion that protrudes from the base portion via a rising portion. Have
Between the housing and the surface light source unit in which the heat dissipation structure is disposed, the protruding portion is not in contact with the surface light source unit, and the heat absorption portion of the heat dissipation structure is the LED. A liquid crystal display device, wherein the liquid crystal display device is disposed in a thermally coupled state.