JP2002278480A - Display panel device - Google Patents

Abstract

(57) [Summary] [Problem] To radiate the heat generated by an LED favorably and suppress image unevenness caused by temperature rise and temperature non-uniformity. SOLUTION: A display panel device 5 includes a substrate 1 and a plurality of LEDs 2r, 2g, 2 arranged on the surface side of the substrate 1.
b, an LED driving device 3 mounted on the back side of the substrate 1, and LEDs 2r, 2 mounted on the front side of the substrate 1.
g, 2b and a metal light-shielding cover 10 provided with an opening 10b at a portion corresponding to the light-emitting portion. The heat generated by each LED is transmitted from the substrate 1 to the metal light-shielding cover 10 via the heat-conducting insulating sheet 12, where it is efficiently radiated, so that the temperature rise of the display panel device is suppressed and the temperature distribution is reduced. Is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display panel device which displays a color image by arranging a plurality of LEDs, each of which emits light of three primary colors of light, as one set and arranging them in a matrix in a matrix. The present invention relates to a display panel device suitable for displaying an image.

[0002]

2. Description of the Related Art FIG. 2A is a plan view (front side) of a conventional display panel device for displaying a color image.
FIG. 2B is a sectional view taken along line IIb-IIb of FIG. As shown in FIG. 2B, this display panel device has a substrate 1
Surface mounted LEDs 2 r, 2 g, 2 b are mounted on the front side of the substrate 1, and an LED driving device 3 is mounted on the back side of the substrate 1. LED2r emits red light, LED
2g emits green light, and LED 2b emits blue light. In this example, a large number of LED groups each including one set of these three LEDs 2r, 2g, and 2b are arranged on the surface of the substrate 1 vertically and horizontally.

A black resin light-shielding cover 4 is attached to the front side of the substrate 1. This light shielding cover 4 is L
This is for making the panel appear black when the ED is turned off. The more the black appears, the higher the contrast ratio becomes and the sharper the color image becomes.

[0004]

In the above-described display panel device, a color image can be displayed by controlling the turning on / off of the individual LEDs on the panel by the LED driving device. However, the red LED2r and the green LED2
As shown in FIG. 3, the light emission luminance characteristics of the g and blue LEDs 2b vary due to temperature changes. In the characteristic example of FIG. 3, the emission luminance of the three-color LED is 30 degrees Celsius.
When the color balance of each color is adjusted in degrees, variations occur as the temperature departs from 30 degrees Celsius. Further, when the LED is used at a high temperature for a long time, the brightness of the LED is deteriorated.

A display panel device for a color image is an LED.
However, since the number of LEDs mounted on a substrate is enormous, the amount of heat generated is large, and the temperature can be reduced by using the display panel device for a long time. If it rises, the brightness between the colors of the color image will vary, which may result in an unclear color image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a display panel device capable of maintaining the clarity of a color image even when used for a long time.

[0007]

According to the present invention, there is provided a display panel device comprising: a substrate; a plurality of LEDs arranged on a front surface of the substrate; an LED driving device for driving the LEDs; A metal light-shielding cover attached to the side and having an opening at a portion corresponding to a light-emitting portion of the LED.

Preferably, in the above, the metal light-shielding cover is tightly fixed to the substrate via a heat conductive insulating sheet, and the surface of the metal light-shielding cover has a light scattering shape. Preferably, the light scattering shape is a shape that does not reflect external light incident from above in a viewing range direction of the display panel (generally, an upper range of 15 ° and a lower range of 35 °). It has a number of protruding ridges provided without extending gaps. More preferably, the cross-sectional shape of each ridge is serrated.

More preferably, in the above, a surface-mounted LED that emits red light and a surface-mounted LE that emits green light
A set of surface-mounted LEDs that emit D and blue light is arranged in rows and columns to display a color image, and the metal light-shielding cover is connected to an earth line.

In the present invention, since the light-shielding cover is made of metal and the light-shielding cover has both the light-shielding function and the heat-dissipating function, it is possible to reduce the cost and suppress image unevenness caused by temperature rise and temperature non-uniformity. Can be. In addition, even if the amount of heat generated is increased by increasing the light emission luminance of the LED, the temperature rise can be suppressed due to the high heat dissipation, so that the light emission luminance can be increased to display a clearer image and suppress the luminance degradation of the LED. It becomes possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1A is a plan view (front side) of a color image display panel device according to an embodiment of the present invention, and FIG. 1B is a line Ib-Ib of FIG. 1A. It is sectional drawing.
The display panel device 5 according to the present embodiment includes a substrate 1 and a large number of surface-mounted LEDs 2 r mounted on the front side of the substrate 1.
2 g and 2 b, an LED driving device 3 provided on the back side of the substrate 1, and a light-shielding cover 10 which is fixed in close contact with the front side of the substrate 1.

LED2r is an LED that emits red light, LED2g is an LED that emits green light,
Reference numeral 2b denotes an LED that emits blue light. In this example, a large number of LED groups each including one set (one pixel) of these three LEDs 2r, 2g, and 2b are arranged on the surface of the substrate 1 vertically and horizontally.

On the front side of the substrate 1, a flat light-shielding cover 10 having an opening at a position where the light-emitting portion of each LED hits is fixed by screws 11.
A sheet 12 having high thermal conductivity and electrical insulation is interposed between them, and they are brought into close contact with each other. Further, the light shielding cover 10 is made of metal in order to enhance heat radiation. The light-shielding cover 10 needs to be lightweight because it is provided on the entire surface of a large-screen display panel device, and is preferably made of a lightweight metal such as aluminum. Further, the metal light-shielding cover 10 is provided on the display panel device 5.
, And unnecessary radiation of electromagnetic waves from the light-shielding cover 10 toward the front of the screen of the display panel device 5 is suppressed.

The light-shielding cover 10 has a surface coated with black paint, and external light 15 (L) such as room illumination light or sunlight entering the display panel device 5 from obliquely above.
It is necessary to have a structure that reflects light other than the EDs 2r, 2g, and 2b) so that the light does not enter the eyes of a person who looks up at the display panel device from below, and the eaves 10a extending in the lateral direction constitute one line (one pixel). Three LEDs are projected from each other (a line in which a row is arranged in a horizontal line). Increasing the length of the eaves 10a increases the light-shielding properties, but hides the LEDs, thereby limiting the visible range of the display panel.

Furthermore, the light-shielding cover 10 according to the present embodiment
Is an opening 10b for exposing the LED light emitting portion.
Small protrusions 10c extending in the lateral direction are also provided on the other surface without any gap. These numerous ridges 10
c has a saw-tooth shape when viewed from the vertical cross section, and the external light 15 incident on the ridge 10c portion.
Are scattered, so that the color of the light-shielding cover 10 looks more black.

Preferably, the upper side 10d (see the enlarged view in the circle shown in FIG. 1 (b)) of the two sides forming the sawtooth shape is perpendicular to the plane of the light shielding cover 10 or External light incident on this side 10d is directed toward the viewing range of the display panel (upper 15).
°, lower 35 °: so as not to reflect light toward the display panel device 5). The shape that scatters external light is
As in this embodiment, a shape other than the ridge 10c extending in the lateral direction may be employed.

In the display panel device 5 having the above-described light-shielding cover 10, the heat generated by the surface-mounted LEDs 2r, 2g, 2b is transmitted to the substrate 1, but the heat of the substrate 1 is
The light is transmitted to the metal light-shielding cover 10 via the heat conductive insulating sheet 12 which is in close contact with the substrate 1 over substantially the entire surface (the entire surface excluding the opening 10b). Since the light-shielding cover 10 is made of metal, it has a high thermal conductivity, and the eaves 10a and a number of ridges 10c function as air-cooling fins for increasing the surface area of the light-shielding cover 10, so that heat can be efficiently released into the air. it can.

Therefore, even if the display panel device 5 is used for a long time, the generated heat is radiated well from the light-shielding cover 10 to suppress the temperature rise of the display panel device 5 and make the temperature distribution uniform. It becomes possible. Therefore, variations in the emission luminance of the three-color LED are suppressed over the entire surface of the display panel device, and it is possible to maintain the clarity of the color image.
Further, it is also possible to increase the light emission luminance of each LED in order to make the screen more easily viewable. In addition, it is possible to suppress the luminance deterioration of the LED.

[0020]

According to the present invention, since the light-shielding cover and the heat radiating mechanism of the display panel device constituting a large screen are also used, it is possible to suppress the display unevenness at low cost and to obtain a clear image. Thus, a display panel device having a long life can be provided by suppressing luminance degradation.

[Brief description of the drawings]

FIG. 1 is a plan view (a) and a cross-sectional view (b) of a display panel device according to an embodiment of the present invention.

FIG. 2 is a plan view (a) and a cross-sectional view (b) of a conventional display panel device.

FIG. 3 is a characteristic graph showing a relationship between light emission luminance of three color LEDs and temperature.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2r, 2g, 2b Surface mount type LED 3 LED drive device 10 Light shielding cover 10a Eave 10b Opening 10c Ridge (light scattering shape) 12 Thermal conductive insulating sheet

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C094 AA01 AA16 AA34 AA37 BA23 CA18 CA24 ED15 5F041 AA14 AA33 DB09 DC07 DC23 EE24 FF01 5G435 AA01 AA12 AA14 AA16 BB04 CC09 CC12 DD11 FF13 GG23 GG26 GG27

Claims (8)

[Claims] A substrate, a plurality of LEDs arranged on a surface side of the substrate, an LED driving device for driving the LEDs, and an opening attached to a surface of the substrate and corresponding to a light emitting portion of the LEDs. A display panel device comprising: a metal light-shielding cover provided. 2. The display panel device according to claim 1, wherein the metal light-shielding cover is closely fixed to the substrate via a heat conductive insulating sheet. 3. The display panel device according to claim 1, wherein the surface of the metal light-shielding cover has a light scattering shape. 4. The light-scattering shape according to claim 3,
A display panel device characterized in that external light incident from above is not reflected to a visible range of the display panel. 5. The display panel device according to claim 3, wherein the light scattering shape is a plurality of ridges provided without a gap extending in a lateral direction. 6. The display panel device according to claim 5, wherein a cross section of each of the ridges has a saw-tooth shape. 7. A set of a surface-mounted LED that emits red light, a surface-mounted LED that emits green light, and a surface-mounted LED that emits blue light according to claim 1, wherein a large number of these are arranged vertically and horizontally. A display panel device, wherein a color image is displayed by arrangement. 8. The display panel device according to claim 1, wherein the metal light-shielding cover is connected to a ground line.