JP2006184350A - Display module - Google Patents

Abstract

An object of the present invention is to provide a display module that eliminates the occurrence of uneven brightness such as an abnormally bright part on the light source side and that can obtain sufficient brightness uniformly over the entire effective display area. On the light exit surface 11b of the light guide plate 11 in the backlight unit 10, the area corresponding to the LED 12 of the flange portion Af between the light emitting area Ae set on this surface and the effective display area Dd included inside thereof In addition, black ink is printed on the diffusion sheet 16 and the light absorbing layer 19 is disposed, so that the light is emitted from the LED 12 and is regularly reflected by the light reflecting sheet 14 to be emitted to the light source side edge of the effective display area Dd. Light rays are absorbed.
[Selection] Figure 1

Description

  The present invention relates to a display module provided with a sidelight type surface emitting backlight using a point light source.

  Conventionally, as a backlight for a flat panel display module such as a liquid crystal display module, a light source is disposed opposite to one end face of a rectangular light guide plate, and light emitted from the light source is guided into the light guide plate and the back of the display panel. A side light type surface emitting backlight that emits in a planar shape from a light emitting area of one main surface opposed to the light source is often used. As a light source in this case, a point light source such as a light emitting diode (hereinafter referred to as an LED (Light Emitting Diode)) is often employed in order to promote a reduction in size and thickness of a display module including a backlight. (For example, see Patent Document 1)

When a surface emitting backlight using the above-described point light source is used, if the output of the LED is increased in order to increase the average brightness of the entire effective display area in the display module, brightness unevenness occurs. It has been difficult to achieve both reductions. In particular, an abnormally bright part (hereinafter referred to as a light source side abnormally bright part) occurs at the light source side edge of the display area.
JP-A-8-313902

  An object of the present invention is to provide a display module in which occurrence of luminance unevenness such as a light source side abnormal bright portion is eliminated and sufficient luminance can be obtained uniformly over the entire display area.

  The display module of the present invention includes a display element that controls transmission of light incident from the back surface and selectively emits light from a display area on the front surface side, and a back disposed on the back side of the display element. A display module having a light, wherein the backlight has a point light source that emits light radially, and an end surface on which the point light source is disposed, and the end light source is arranged to face the point light source. A light guide plate that emits incident light and emits in a planar shape toward the display element from a light emitting area that includes an effective display area, which is an illumination area of the display area, by internal reflection, the light guide plate, and the display element Between the light emitting area and the outer area of the effective display area between the light emitting areas, and corresponding to the brightness unevenness to reduce the brightness unevenness generated in the display area And it is characterized in that comprising the Osamuso.

According to the display module of the present invention, the light absorption layer is installed at a position corresponding to the luminance unevenness generated in the display area inside the light emitting area between the light guide plate and the display element and outside the effective display area. As a result, the luminance unevenness is effectively eliminated by minimizing the decrease in the effective light amount used for display due to the installation of the light absorption layer, and the display area has sufficient brightness and uniform high display quality over the entire display area. It is done.

  In the display module of the present invention, it is preferable that a light diffusion sheet is further disposed between the light guide plate and the display element, and the light absorption layer is disposed at a position corresponding to the point light source of the light diffusion sheet. Thus, the light that is the main factor for generating the light source side abnormal bright portion is absorbed by the light absorption layer, and the generation of the light source side abnormal bright portion can be reliably prevented.

  Further, in the display module of the present invention, it is preferable that the light absorption layer is installed in a shape corresponding to the shape of the luminance unevenness generated in the display area, thereby absorbing light that is not involved in the occurrence of luminance unevenness. An extremely high quality display with sufficient and uniform brightness can be obtained over the entire display area.

  Furthermore, in the display module of the present invention, it is preferable that the light absorption layer is formed by printing using black ink, whereby a light absorption layer having a good light absorption rate can be accurately and easily formed at a predetermined position. it can.

Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing a liquid crystal display module as one embodiment of the present invention.

  The casing of the present liquid crystal display module is configured such that a cover case 2 with a bottom plate removed is fitted to a storage case 1 with a bottom plate removed from a storage case 1 in which a top plate of a box having a flat outer shape is removed. The storage case 1 is formed in a structure having a two-stage storage space using a resin material by, for example, an injection molding method. That is, two spaces of a lower space and an upper space wider than the step 1c by an area of the step 1c are formed at a predetermined height position of the side wall 1b erected on the peripheral edge of the bottom plate 1a. The storage space is formed in two stages.

  A liquid crystal display panel 3 is stored in the upper space of the storage case 1. The liquid crystal display panel 3 is joined to a pair of glass substrates 4 and 5 on which electrodes (not shown) are formed, with a predetermined gap maintained by a frame-shaped sealing material (not shown) with the respective electrode forming surfaces facing each other. The liquid crystal is sealed between the glass substrates 4 and 5 surrounded by the frame-shaped sealing material. A pair of front and rear polarizing plates 6 and 7 are attached to the outer surfaces of the glass substrates 4 and 5, respectively. The liquid crystal display panel 3 of the present embodiment is an active matrix type liquid crystal display panel, and a plurality of pixel electrodes (not shown) are arranged in a matrix arrangement on the inner surface of one of the pair of glass substrates 4 and 5, for example, the glass substrate 5. A single-layered counter electrode (not shown) is provided on the inner surface of the other glass substrate 4 opposite to the glass substrate 4. And the opposing part of these both electrodes becomes a pixel part, and the display area in which these pixel parts are arranged in a matrix is formed. Here, the effective display area Dd in which an image is actually displayed is defined by a black mask (not shown) disposed on the outer periphery of an area where pixels arranged in a matrix are gathered. Note that this black mask is usually disposed between pixels.

  One glass substrate 5 out of the glass substrates 4 and 5 is formed with an extending portion 5 a by extending an edge portion outward from a corresponding end surface of the other glass substrate 4. On the surface of the extended portion 5a (extension surface of the electrode forming surface), connection terminals (not shown) of the lead wirings connected to the electrodes of the substrates 4 and 5 are arranged in parallel.

  A driving circuit element 8 for driving the liquid crystal is directly mounted on the extending portion 5a in which the above-described lead wiring and connection terminal row are formed by a COG (Chip On Glass) method. A flexible wiring board 9 that electrically connects a drive control circuit board (not shown) for controlling the drive of the entire liquid crystal display module and the drive circuit element 8 is conductively joined to the edge of the extension part 5a. Yes.

  A backlight unit 10 is stored in a lower space of the storage case 1. The backlight unit 10 of the present embodiment generally includes a light guide plate 11, a light emitting diode 12 as a point light source, a light reflecting sheet 14 that prevents light leakage, and an optical sheet laminate 15 for adjusting irradiation light.

  FIG. 2 is a plan view showing the configuration of the backlight unit 10 by removing the cover case 2 and the liquid crystal display panel 3 of the present liquid crystal display module. As shown in FIG. 2, the light guide plate 11 is formed in a substantially rectangular plate shape using a transparent resin material such as acrylic resin, and one end surface of the four side end surfaces is an incident end surface 11 a on which light is incident. In the incident end face 11 a, two concave portions 11 b and 11 b are formed symmetrically with respect to the width center line of the light guide plate 11. In these recesses 11b and 11b, LEDs 12 and 12 as point light sources are installed with their respective light exit surfaces in close contact with the respective back wall surfaces of the recesses 11b and 11b. These LEDs 12 and 12 are directly mounted on the flexible wiring board 13, and this flexible wiring board 13 is extended outside the storage case 1, and the wiring formed on the flexible wiring board 13 is electrically connected to the drive control circuit board. It is connected.

  In the light guide plate 11, one main surface 11c of a pair of main surfaces extending at right angles to the light incident end surface 11a is used as a light emitting surface (front surface) from which light is emitted, and is opposite to the light emitting surface 11c. A plurality of fine grooves 11e are formed in the main surface (rear surface) 11d on the side. The fine groove 11e is formed in a pattern in which two concentric circles each centering on the LEDs 12 and 12 intersect. When light propagating through the light guide plate 11 enters the micro grooves formed in the concentric pattern, the incident light is reflected toward the front surface 11c serving as a light exit surface, and the liquid crystal display panel 3 to be irradiated from the front surface 11c. It is emitted toward the back.

  A light reflecting film 14 is provided on the rear surface 11 d of the light guide plate 11. The light reflecting film 14 is provided to reflect light that propagates in the light guide plate 11 and is not reflected by the minute grooves 11e on the rear surface 11d and is emitted to the outside and reenters the light guide plate 11. The light reflecting film 14 of this example is formed by depositing silver on a PET (Poly-Ethylene Terephthalate) film, and has a high light reflectance.

  On the front surface 11 c of the light guide plate 11, a light emitting area Ae for emitting light is defined. The area and position of the light emitting area Ae are set so that the effective display area Dd of the liquid crystal display panel 3 that is the irradiation target of the backlight unit 10 is included inside with the flange portion Af having the width W secured. . And the optical sheet laminated body 15 is installed over the whole surface of this light emission area Ae. The optical sheet laminate 15 is formed by laminating a diffusion sheet 16 and two prism sheets 17 and 18 in order from the light guide plate 11 side.

  The diffusion sheet 16 is provided for diffusing and transmitting the light emitted from the light emitting area Ae so as to make the luminance distribution of the planar emitted light uniform, and is a surface on the light emitting side of a transparent base sheet such as PET. And a light diffusing layer.

  The prism sheets 17 and 18 are provided to collect the light emitted from the light guide plate 2 diffused by the diffusion sheet 16 toward the liquid crystal display panel 3 to be irradiated. The prism sheets 17 and 18 of this example are prism sheets in which a plurality of protrusions (not shown) are formed in parallel on one main surface, and are installed with the extending directions of the protrusions orthogonal to each other. .

  A light absorbing layer 19 is disposed on the flange portion Af in the light emitting area Ae on the light exit surface 11 c of the light guide plate 11. The light absorption layer 19 is provided in order to eliminate luminance unevenness that occurs in the display area of the liquid crystal display panel 3, and is therefore provided corresponding to the shape of the uneven luminance that occurs and the position where it occurs. Yes.

  The light absorption layer 19 of the present embodiment is provided to eliminate the light source side abnormal bright portion generated at the light source side edge portion in the display area of the liquid crystal display panel 3, and therefore, as shown in FIG. In the flange portion Af, the LED 12 is disposed in two areas corresponding to the LEDs 12 and 12 on the side. Each light absorption layer 19 has a slightly larger semi-elliptical shape that is substantially similar to the light source-side abnormal bright portion Pb that is formed in a semi-elliptical shape.

  In the present embodiment, the light absorption layer 19 is formed on the back surface of the diffusion sheet 16 where the light diffusion layer of the base sheet is not provided, and is formed into a thin layer having a thickness of about 10 μm by printing with black ink. Has been. Here, the color of the light absorption layer 19 can be easily ensured sufficient light absorption ability by making it black as in this example. However, the color is not limited to black, and other luminance unevenness is not so bright. For example, a dark color such as gray may be used. The layer thickness is not limited to 10 μm. In other words, the light absorption layer 19 of the present invention may be formed so as to have a light absorption capability necessary and sufficient to surely eliminate the uneven brightness that occurs.

  In the present embodiment, since the light absorption layer 19 is formed by printing, as described above, the light absorption layer 19 that has an extremely thin layer thickness of about 10 μm and whose arrangement position should be set strictly is also easily and accurately laminated. Can be formed. In addition, as a light absorption layer formation method, other methods, such as sticking a black film, are employable irrespective of ink printing.

  The flexible wiring board 13 on which the LEDs 12 described above are mounted is disposed in an area excluding the light emitting area Ae on the light source side on the light emitting surface 11c of the light guide plate 11.

  In the backlight unit 10 configured as described above, light emitted from the LEDs 12 and 12 is incident on the rear surface 11d of the light guide plate 11 at an angle θ smaller than the total reflection angle, for example, as a light ray R. The light rays are regularly reflected by the light reflecting film 14 and incident on the light absorbing layer 19 to be absorbed. Accordingly, in the conventional case where the light absorption layer 19 is not provided, the light is emitted from the light emitting surface (front surface) 11c as indicated by a two-dot chain line, and the light source side abnormally bright portion Pb (see FIG. 2), in the present embodiment, a light ray such as the light ray R is absorbed by the light absorption layer 19, so that the occurrence of the light source side abnormal bright portion Pb is surely prevented.

  In addition, since the setting area of the light absorption layer 19 and its shape and layer thickness are optimally set corresponding to the uneven luminance, that is, the light source side abnormal bright portion Pb, the luminance of the light source side abnormal bright portion Pb is set to other portions. Not only is the brightness reduced to substantially the same level as the brightness, but also the light emitted from the vicinity of the area where the light source side abnormal bright part Pb is generated is not absorbed, so that the occurrence of a problem of lowering the brightness in the vicinity area is reliably prevented. Further, the brightness is made more uniform over the entire display area of the liquid crystal display panel 3.

In addition, this invention is not limited to said embodiment.
For example, the light absorption layer 19 may be applied and formed on either or both of the prism sheet 17 and the prism sheet 18 without being applied to the diffusion sheet 16.

  In the above embodiment, the light absorbing layer is provided at the light source side point light source corresponding position at the flange portion of the light emitting area in order to eliminate the light source side abnormal bright portion. When an abnormally bright portion is generated on the side opposite to the light source, a light absorption layer may be provided on the flange portion on the side opposite to the light source corresponding to this.

  Further, the present invention is not limited to the liquid crystal display module, but can be applied to other various flat panel display modules having a surface emitting backlight using a point light source.

It is a typical sectional view showing the whole liquid crystal display module composition as one embodiment of the present invention. It is a top view which shows the principal part structure of the liquid crystal display module shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage case 2 Cover case 3 Liquid crystal display panel 4, 5 Glass substrate 6, 7 Polarizing plate 10 Backlight unit 11 Light guide plate 12 LED
13 Flexible wiring board (LED cable)
14 Light reflection sheet 15 Optical sheet laminate 16 Diffusion sheets 17 and 18 Prism sheet 19 Light absorption layer

Claims (4)

A display element that controls transmission of light incident from the back surface and selectively emits light from the display area on the front surface side; and
A display module having a backlight disposed on the back side of the display element,
The backlight is
A point light source that emits light radially,
It has an end face on which the point light source is arranged, and the light emitted from the point light source is incident from an end face facing the point light source, and includes an effective display area that is an illumination area of the display area by internal reflection. A light guide plate that emits in a planar shape from the light emitting area toward the display element;
Corresponding to the luminance unevenness for reducing the luminance unevenness generated in the display area in the area between the light guide plate and the display element, inside the light emitting area and outside the effective display area. A display module comprising an installed light absorption layer. A light diffusion sheet is further disposed between the light guide plate and the display element;
The display module according to claim 1, wherein the light absorption layer is installed at a position corresponding to the point light source of the light diffusion sheet.   The display module according to claim 1, wherein the light absorption layer is installed in a shape corresponding to a shape of uneven brightness generated in the display area.   The display module according to any one of claims 1 to 3, wherein the light absorption layer is a black ink layer disposed by printing.

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