JP2010060589A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein reduction in contrast due to a color filter layer is suppressed. <P>SOLUTION: The liquid crystal display device includes: a first substrate; a second substrate facing the first substrate; a liquid crystal layer provided between the first substrate and the second substrate; a layer of a TFT array provided between the first substrate and the liquid crystal layer; a first polarizing plate provided on the side opposite from the liquid crystal layer, of the first substrate; a second polarizing plate provided on the side opposite from the liquid crystal layer, of the second substrate; a third substrate provided so as to face the side opposite from the liquid crystal layer, of the second substrate; and a color filter layer provided on a surface which is one surface of the third substrate and faces the second substrate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device.

  In a transmissive color liquid crystal display device, the amount of light transmitted from a light source is adjusted for each sub-pixel such as red, blue, and green by combining a liquid crystal layer and a polarizing plate.

  FIG. 2 is a diagram schematically showing a part of a cross section of a conventional liquid crystal display device. The liquid crystal display device includes a first substrate SUB1 and a second substrate SUB2, and a liquid crystal layer LC exists between the first substrate SUB1 and the second substrate SUB2. A TFT in which a lower polarizing plate PL1 is attached to a surface of the first substrate SUB1 opposite to the liquid crystal layer LC, and a TFT element, a pixel electrode, or the like is formed on the surface of the first substrate SUB1 on the liquid crystal layer LC side. An array TA is provided. The color filter layer CF is provided on the surface of the second substrate SUB2 on the liquid crystal layer LC side, and the thickness of the liquid crystal layer LC between the first substrate SUB1 and the second substrate SUB2 by the gap control column SOC. Is kept constant. An upper polarizing plate PL2 is arranged on the surface of the second substrate SUB2 opposite to the liquid crystal layer LC. The first substrate SUB1 and the second substrate SUB2 are glass substrates. The color filter layer CF includes a red color layer SPR, a green color layer SPG, a blue color layer SPB, and a light-shielding film (black matrix) BM that exists so as to fill in the space between these color layers.

  Light from a light source such as a backlight is incident on the lower polarizing plate PL1 from the direction opposite to the first substrate SUB1. The light is transmitted in the order of the first substrate SUB1, the TFT array TA, and the liquid crystal layer LC, and becomes polarized light aligned in a certain direction. The light further passes through the color filter layer CF, the second substrate SUB2, and the upper polarizing plate PL2. In the liquid crystal display device, the amount of light of each sub-pixel is adjusted based on the relationship between the polarization direction controlled by the lower polarizing plate PL1 and the liquid crystal layer LC and the polarization direction passed through the upper polarizing plate PL2. In the column of the prior art of Patent Document 1, the above-described conventional liquid crystal display device and a touch panel display device configured by mounting a touch sensor on the display surface of the liquid crystal display device are disclosed.

In addition, there are Patent Documents 2 and 3 as documents related to the present application, which describe liquid crystal display devices in which color filter layers are provided at different positions.
JP 2008-32756 A JP-A-6-82614 JP 11-119206 A

  In a general color filter, a pigment is used as a colorant constituting the color filter. Although pigments are indispensable for maintaining durability, light scattering tends to occur. Due to the scattering of the light, the state of polarized light whose direction is aligned by the lower polarizing plate PL1 or the like collapses, and it is difficult to strictly control the amount of light transmitted through the upper polarizing plate PL2. Specifically, there is a problem that light that should not pass through in black display is transmitted through the upper polarizing plate PL2, and the contrast of the liquid crystal display is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display device in which a reduction in contrast due to a color filter layer is suppressed.

Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  (1) a first substrate, a second substrate facing the first substrate, a liquid crystal layer provided between the first substrate and the second substrate, the first substrate, and the A TFT array layer provided between the liquid crystal layer, a first polarizing plate provided on a surface of the first substrate opposite to the liquid crystal layer, and a side opposite to the liquid crystal layer of the second substrate A second polarizing plate provided on the surface of the second substrate, a third substrate provided opposite to the surface of the second substrate opposite to the liquid crystal layer, and one surface of the third substrate, And a color filter layer provided on a surface facing the second substrate.

  (2) The liquid crystal display device according to (1), wherein the third substrate constitutes a touch panel.

  (3) The liquid crystal display device according to (1), further including a touch sensor layer provided on a surface of the third substrate opposite to the color filter layer.

  (4) The liquid crystal display device according to (1), wherein the color filter layer includes a color layer and a light shielding film, and the color layer includes a pigment.

  (5) The liquid crystal display device according to (1), wherein light from a light source is incident on a surface of the first polarizing plate opposite to the first substrate.

  According to the present invention, polarized light aligned in a certain direction by the lower polarizing plate, the liquid crystal layer, or the like is incident on the upper polarizing plate without passing through the color filter layer. Therefore, the amount of light transmitted through the upper polarizing plate can be controlled more strictly, and the reduction in contrast can be suppressed.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing a part of a cross section of a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device includes a first substrate SUB1, a second substrate SUB2, and a third substrate SUB3. Each substrate is a glass substrate. The first substrate SUB1 and the second substrate SUB2 face each other, and the liquid crystal layer LC exists between them. The third substrate SUB3 faces the surface of the second substrate SUB2 opposite to the liquid crystal layer LC.

  A TFT array in which a lower polarizing plate PL1 is disposed on the surface of the first substrate SUB1 opposite to the liquid crystal layer LC, and TFT elements, pixel electrodes, and the like are formed on the surface of the first substrate SUB1 on the liquid crystal layer LC side. TA is arranged. The thickness of the liquid crystal layer LC between the first substrate SUB1 and the second substrate SUB2 is kept at a predetermined interval by a gap control column (columnar spacer) SOC formed on the liquid crystal layer side of the second substrate SUB2. I'm leaning. An upper polarizing plate PL2 is arranged on the surface of the second substrate SUB2 opposite to the liquid crystal layer LC. The upper polarizing plate PL2 is provided on the second substrate SUB2, which is a glass substrate, similarly to the conventional liquid crystal display device. Although not shown, alignment films are formed on the liquid crystal layer side of the second substrate SUB2 and the liquid crystal layer side of the TFT array TA. The relationship between the direction through which the polarized light of the lower polarizing plate PL1 passes, the direction through which the polarized light of the upper polarizing plate PL2 passes, and the arrangement of the liquid crystal molecules in the liquid crystal layer LC may be the same as in a general liquid crystal display panel. . Although the common electrode is not particularly illustrated, it is provided on the liquid crystal layer side of the second substrate SUB2 in the TFT array TA in the case of the IPS method, or in the second substrate SUB2 in the case of the TN method or VA method. .

  Of the two surfaces of the third substrate SUB3, the color filter layer CF is provided on the surface facing the second substrate SUB2. The color filter layer CF includes a red color layer SPR, a green color layer SPG, a blue color layer SPB, and a light-shielding film (black matrix) BM that exists so as to fill in the space between these color layers. Here, the pixels of the display screen of the liquid crystal display device each include red, green, and blue sub-pixels, and the color layer SPR, the color layer SPG, and the color layer SPB are provided for each of the sub-pixels. The dye used for the color layer is a pigment-based dye, and a protective film layer (not shown) is formed on the surface of the color filter layer CF opposite to the third substrate SUB3.

  Further, the third substrate SUB3 constitutes a touch panel. Of the two surfaces of the third substrate SUB3, the touch sensor layer TL is provided on the surface opposite to the surface facing the second substrate SUB2. The touch sensor layer TL may be a layer using a known touch sensor technology. For example, in the case of a resistive film method, the touch sensor layer TL is a layer in which two transparent conductive films are provided with an air layer interposed therebetween. If so, it is a layer made of a transparent conductive layer for detecting a change in charge. The touch sensor layer TL may have a structure in which a fourth substrate is provided in accordance with the touch sensor method.

  The third substrate SUB3 is fixed to the second substrate SUB2 with an adhesive in the frame region (peripheral portion). In FIG. 1, although it appears that there is a gap between the upper polarizing plate PL2 provided on the surface of the second substrate SUB2 and the color filter layer CF, the color filter layer CF is formed on the surface of the third substrate SUB3. This is an expression for emphasizing that it is provided, and the protective film layer of the color filter layer CF and the upper polarizing plate PL2 are actually in close contact with each other.

  Light from a light source such as a backlight (not shown) enters the lower polarizing plate PL1 from the direction opposite to the first substrate SUB1. The light is transmitted in the order of the first substrate SUB1, the TFT array TA, and the liquid crystal layer LC, and becomes polarized light aligned in a certain direction. Then, the light passes through the second substrate SUB2 and the upper polarizing plate PL2 as it is. That is, since the polarized light transmitted through the liquid crystal layer LC enters the upper polarizing plate PL2 without passing through the color filter layer CF, the polarized light contained in the color layer SPR, the color layer SPG, or the color layer SPB constituting the color filter layer CF. It will not be scattered. Therefore, the light quantity of each sub-pixel can be adjusted more strictly in relation to the direction of polarized light passing through the upper polarizing plate PL2, and as a result, the contrast of the liquid crystal screen can be improved. This is because light whose polarization is broken is reduced, light leakage in black display is reduced, and unexpected light blocking in maximum light quantity display is also reduced. The light corresponding to each sub-pixel transmitted through the upper polarizing plate PL2 is transmitted through any one of the color layer SPR, the color layer SPG, and the color layer SPB of the color filter layer CF, and the third substrate SUB3 and the touch sensor layer TL. And output as an image.

  Although the embodiments have been described so far, the present invention is not limited to the embodiments described above. For example, in the embodiment, the touch sensor layer TL is provided on the surface of the third substrate SUB3 opposite to the second substrate SUB2, but instead, between the third substrate SUB3 and the color filter layer CF, The color filter layer CF may be provided on the surface opposite to the surface on the third substrate SUB3 side. There is no change in the point where light from the light source passes through the color filter layer CF after passing through the upper polarizing plate PL2, and if it is a capacitive touch sensor, it operates as a touch sensor even if there is an insulating layer between them. Because.

It is a figure which shows typically a part of cross section of the liquid crystal display device which concerns on embodiment of this invention. It is a figure which shows typically a part of cross section of the conventional liquid crystal display device.

Explanation of symbols

  SUB1 first substrate, SUB2 second substrate, SUB3 third substrate, TA TFT array, LC liquid crystal layer, CF color filter layer, PL1 lower polarizing plate, PL2 upper polarizing plate, SPR red color layer, SPG green Color layer, SPB blue color layer, SOC gap control pillar, TL touch sensor layer.

Claims (5)

A first substrate;
A second substrate facing the first substrate;
A liquid crystal layer provided between the first substrate and the second substrate;
A layer of a TFT array provided between the first substrate and the liquid crystal layer;
A first polarizing plate provided on a surface of the first substrate opposite to the liquid crystal layer;
A second polarizing plate provided on the surface of the second substrate opposite to the liquid crystal layer;
A third substrate provided facing the surface of the second substrate opposite to the liquid crystal layer;
A liquid crystal display device comprising: a color filter layer provided on one surface of the third substrate and facing the second substrate. The third substrate constitutes a touch panel;
The liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 1, further comprising a touch sensor layer provided on a surface of the third substrate opposite to the color filter layer. The color filter layer comprises a color layer and a light shielding film,
The color layer includes a pigment;
The liquid crystal display device according to claim 1. Light from a light source is incident on a surface of the first polarizing plate opposite to the first substrate;
The liquid crystal display device according to claim 1.

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