CN100381902C - Color liquid crystal panel, manufacturing method thereof, and color liquid crystal display using the color liquid crystal panel - Google Patents

Abstract

A color liquid crystal panel, a manufacturing method thereof and a color liquid crystal display using the color liquid crystal panel. In the reflective display part R of the liquid crystal panel, part of the light that reaches the reflective electrode through the color filter is emitted to the outside through the slit, and part of the light that reaches the reflective electrode through the slit is emitted to the outside through the color filter. In addition, light that reaches the reflective electrode through the color filter and is emitted to the outside through the color filter, and light that has no chance to pass through the slit can also be observed. Therefore, the average film thickness of the color filter through which the light passes is approximately equal to the film thickness observed in the transmissive display portion T during the time when the light is input to the inside until it travels the corresponding distance to the outside. In addition, since the ratio of the area of the slit to the area of the corresponding color filter can be changed according to the color to be displayed, the color reproduction range of the reflective display portion R and the color reproduction range of the transmissive display portion T can be made according to the color to be displayed. colors are consistent with each other.

Description

Color liquid crystal panel, manufacturing method thereof, and color liquid crystal display using the color liquid crystal panel

technical field

The present invention relates to a color liquid crystal panel suitable for use as a display of a portable phone, a method of manufacturing the same, and a color liquid crystal display using the color liquid crystal panel. More particularly, the present invention relates to a color liquid crystal panel having enhanced ability to display high-quality images, a method of manufacturing the same, and a color liquid crystal display using the color liquid crystal panel.

Background technique

As we know, as a liquid crystal display having both the characteristics of a transmissive liquid crystal display and the characteristics of a reflective liquid crystal display, a liquid crystal display composed of a plurality of pixels and each pixel has a transmissive display part and a reflective display part Transflective liquid crystal displays have been developed. In this transflective liquid crystal display, corresponding to each color to be displayed, a color filter for the transmissive display part and a color filter for the reflective display part are respectively provided, therefore, corresponding to each color, a total of 6 color filters. Thus, in order to manufacture a color liquid crystal display having the above-mentioned color filter structure, it is necessary to prepare six types of photoresist films corresponding to these color filters, and then perform six photolithography steps. Therefore, it can be found that such a defect is that the transflective liquid crystal display manufactured according to the above method has the problems of low yield and high manufacturing cost.

In view of the above disadvantages, a transflective liquid crystal display described below has recently been disclosed in various publications such as Japanese Patent Application Laid-Open No. 2000-111902. In the structure of the transflective type liquid crystal display, only one kind of color filter is formed corresponding to each color, and an area in which no color filter exists is formed within the reflective display portion.

FIG. 1 is a plan view showing the structural layout of a TFT substrate included in a conventional transflective type liquid crystal display disclosed in Japanese Patent Application Laid-Open No. 2000-111902. 2 is a sectional view of a liquid crystal panel used in a conventional transflective type liquid crystal display, taken along line A-A in FIG. 1 .

In the conventional transflective liquid crystal display disclosed in the above publication, red pixels 101R, green pixels 101G, and blue pixels 101B are arranged in this order along the extending direction of the scanning signal lines. One thin film transistor (TFT) 102 is formed in each pixel. The thin film transistor 102 is composed of a gate electrode 103a extending from a gate line 103 serving as a scanning signal line, and a drain electrode 104a extending from a drain line 104 extending in a direction perpendicular to the gate line. The gate lines 103 and the gate electrodes 103a are formed on a transparent substrate 100a, and an insulating film 105 is formed on the transparent substrate 100a to cover the gate lines 103 and the gate electrodes 103a. Drain line 104 is formed on insulating film 105 . An amorphous silicon layer 106 is formed on the insulating film 105 opposite to the gate electrode 103a, and the drain electrode 104a extends on the amorphous silicon layer 106. In addition, there is a source electrode 107 extending from the amorphous silicon layer 106 in a direction away from the drain electrode 104a, and a portion of the source electrode is located at least on and in the amorphous silicon layer.

A convex portion 108 is formed on the insulating film 105 in the reflective display portion of each pixel, and a transparent electrode 109 is formed on the insulating film 105 in the transmissive display portion. Note that the reflective display portion surrounds the transmissive display portion. In addition, an insulating film 110 covering the convex portion 108, the thin film transistor 102, etc. is formed in a region other than the transmissive display portion of each pixel, and a contact hole 111 is formed in the insulating film 110 to extend to the source electrode 107. s surface. Reflective electrode 112 is formed within contact hole 111 and over insulating film 105 . The reflective electrode 112 has a concave-convex surface that reflects the contour of the convex portion 108 . The reflective electrode 112 is also connected to the transparent electrode 109 . In addition, a retardation film 113 and a polarizer 114 are formed on the side of the transparent substrate 100a where elements such as the thin film transistor 102 are not formed. The above elements constitute the TFT substrate.

In addition, there is another transparent substrate 100b placed parallel to the side of the transparent substrate 100a on which the thin film transistor 102 is formed. A color filter (CF) 121 and a counter electrode 122 are formed on one side surface of the transparent substrate 100b facing the transparent substrate 100a. As shown in FIG. 1, the color filter 121 extends parallel to the drain line 104, and when one pixel is viewed from a direction perpendicular to the surface of the corresponding transparent substrate, transparent electrodes 109 are formed within both end lines of the color filter 121, And the width of the reflective electrode 112 exceeds the two end lines. In addition, a retardation film 123 and a polarizer 124 are formed on the side of the transparent substrate 100b on which elements such as the color filter 121 are not formed. The above components constitute the CF substrate.

In addition to the above liquid crystal panel structure, a liquid crystal 130 is injected between the TFT substrate and the CF substrate to form a liquid crystal panel.

In the conventional color liquid crystal display having the above structure, there is a color filter corresponding to each color, so it has a smaller number of process steps in the manufacturing process, so that the yield rate can be improved.

In addition, in the color filter 121 of the CF substrate used as the above-mentioned color liquid crystal display, there is a region facing the reflective electrode 112, and the color filter 121 is not formed in this region, so that this color liquid crystal display can provide a ratio of The color liquid crystal display using the color filter 121 having such a structure has higher brightness than that achieved by the color liquid crystal display developed before the appearance.

In addition, in a conventional reflective liquid crystal display, a plurality of convex portions are formed in various directions under the reflective electrode. These raised portions are designed to have an optimal pattern in terms of the path of incident and reflected light. FIG. 3 shows the layout of raised portions employed in a conventional liquid crystal display. In a reflective liquid crystal display, the raised portion 108 does not particularly consider the boundary effect between pixels. In addition, a liquid crystal display having a transmissive display portion and a reflective display portion includes such raised portions only in the reflective display portion.

However, compared with liquid crystal displays using two kinds of color filters that were developed before the appearance of liquid crystal displays using one color filter, in this type of color filter corresponding to each color, only one kind of color filter is used for the manufacturing process of the product. There is a problem in conventional transflective liquid crystal displays in which, for example, the number of process steps is reduced, that is, their image quality is poor.

In addition, there is another problem that images displayed by the reflective type liquid crystal display and the transflective type liquid crystal display may appear yellowish in color.

Contents of the invention

An object of the present invention is to provide a color liquid crystal panel capable of improving the image quality displayed in a transflective type liquid crystal display, a manufacturing method thereof, and a color liquid crystal display using the color liquid crystal panel.

The color liquid crystal panel according to the first aspect of the present invention includes: a thin film transistor, a reflective electrode connected to the thin film transistor, and a transparent electrode located in each pixel. The color liquid crystal panel has such a structure that the display surface of the color liquid crystal panel allows the light emitted from the backlight to exit the display surface through the transparent electrode, and allows other light input to the display surface to also be reflected by the reflective electrode. Exit from the display surface. In addition, the color liquid crystal panel also has such a structure that the color liquid crystal panel contains a color filter, and at least one opening that can be changed according to the color to be displayed is formed in a part of the color filter facing the reflective electrode. , and the color reproduction range of the light emitted from the display surface through the transparent electrode and the other light emitted from the display surface after being reflected by the reflective electrode are basically consistent with each other.

It should be noted that the color liquid crystal panel according to the first aspect of the present invention is preferably constituted as follows. That is, a red color filter, a green color filter, and a blue color filter are respectively formed as color filters, and the ratio of the area of at least one opening formed in the color filter to the area of the color filter is important in selecting the green filter color. When the film is used as a color filter to calculate the ratio, it is the maximum value. The color liquid crystal panel preferably also constitutes according to the following content, that is, in the case of using a white light source as the backlight, the ratio of the area of at least one opening formed in the green color filter to the area of the green color filter is equal to that of the red color filter. and the ratio of the area of at least one opening formed in the blue color filter to the area of the corresponding red color filter or blue color filter is two to four times.

In addition, the color liquid crystal panel according to the first aspect of the present invention is preferably further constituted as follows, that is, the area of at least one opening formed in the color filter is the same as that of the color filter facing the reflective electrode among the color filters. The area ratio of the portions is set to a value not greater than 50%, and at least one opening is formed like a slit, and its slit width is set to a value of 1 μm to 10 μm.

The color liquid crystal panel according to the second aspect of the present invention includes: a thin film transistor, a reflective electrode connected to the thin film transistor, and a transparent electrode located in each pixel. The color liquid crystal panel has such a structure that the display surface of the color liquid crystal panel allows the light emitted from the backlight to exit the display surface through the transparent electrode, and allows other light input to the display surface to also be reflected by the reflective electrode. Exit from the display surface. In addition, the color liquid crystal panel also contains a color filter and a transparent film formed between the color filter and the transparent substrate and whose volume can be changed according to the color to be displayed. The color restoration range of the light emitted from the display surface and other light emitted from the display surface after being reflected by the reflective electrode is basically consistent with each other.

A color liquid crystal panel according to a third aspect of the present invention includes: a transparent substrate, a thin film transistor formed in each pixel on the transparent substrate, an insulating film formed on the transparent substrate and having a concave-convex surface in each pixel, and an insulating film formed on the insulating film. And reflective electrodes connected to the thin film transistors in each pixel. In this color liquid crystal panel, the insulating film contains a plurality of raised parts, each raised part extends along the border of adjacent pixels, and each raised part The widths are all substantially equal to the width of the convex portions constituting the concave-convex surface in each pixel.

In order to solve the above-mentioned problems, the inventors of the present application actively and repeatedly conducted experiments and studies, and finally found that the following problems exist in the conventional technology such as disclosed in Japanese Patent Application Laid-Open No. 2000-111902. That is, in transmissive and reflective liquid crystal displays having only one kind of color filter corresponding to the color to be displayed, even if human visual sensitivity changes with the displayed color, the respective opening patterns formed in the corresponding color filter are also consistent with each other. Therefore, for the color filter with such an opening, its structure will make the color reproduction ranges of the transmissive display part and the reflective display part in the pixel different from each other, so that the transmissive and reflective liquid crystal displays cannot provide high-quality display images . The present invention conceives a liquid crystal panel having the following structure in consideration of the negative influence on display image quality. That is, as described above, the opening area formed in the color filter in the reflective display portion is changed according to the displayed color, or a transparent film is formed between the color filter and the transparent substrate while making the volume of the transparent film according to the displayed color. color changes. This liquid crystal panel structure can make the color reproduction range of the transmissive display part and the reflective display part correspond to the respective colors to be displayed. , to produce a color-balanced visual image according to each color to be displayed, thereby realizing a high-quality image.

In addition, the inventors also found that the light yellow color of the image is caused by differences in the gaps between the two substrates located within the pixels and between the pixels. Generally, in a reflective liquid crystal display, a black matrix is not formed at a boundary between pixels to brighten a display. For this reason, it is believed that the above-mentioned difference in the gap causes the light to travel different distances when passing through the liquid crystal, thereby causing a phase difference in the light, which in turn causes the color of the image to be slightly yellowish. Therefore, the liquid crystal panel of the present invention is made such that the raised portion is also formed at the boundary between pixels, which reduces the difference in gaps, thereby reducing buff and realizing high-quality images.

A method for manufacturing a color liquid crystal panel according to the present invention is constituted as follows. First, the color liquid crystal panel includes thin film transistors, reflective electrodes connected to the thin film transistors, and transparent electrodes in each pixel, and it is also made so that the display surface of the color liquid crystal panel allows light emitted from the backlight to pass through the transparent electrodes exit from the display surface, and allow other light input to the display surface to also exit from the display surface after being reflected by the reflective electrode. Next, the method for manufacturing the above-mentioned color liquid crystal panel includes the steps of: preparing a photomask in such a manner that at least one opening is formed in the photomask, and the area of the at least one opening can be adjusted according to the desired area. The displayed color is changed; using this photomask, a mask pattern is formed in the raw material film constituting the color filter, so that the color filter contains at least one electrode that can be changed according to the color to be displayed and faces the reflective electrode. Open your mouth.

It should be noted that, for this method for manufacturing a color liquid crystal panel, it preferably further includes the step of forming a transparent film to cover all the color filters formed corresponding to the colors to be displayed, and A step of flattening the transparent film after the forming step.

According to the above method for manufacturing a color liquid crystal panel, a color liquid crystal panel according to the first aspect of the present invention and capable of displaying high-quality images can be manufactured.

In addition, a color liquid crystal display according to the present invention comprises a liquid crystal panel constructed according to the first, second and third aspects of the present invention.

Description of drawings

1 is a plan view showing the structural layout of a TFT substrate included in a conventional transflective liquid crystal display disclosed in Japanese Patent Application Laid-Open No. 2000-111902;

Fig. 2 is a sectional view of a liquid crystal panel used in a conventional transflective liquid crystal display obtained along line A-A in Fig. 1;

FIG. 3 shows the layout of raised portions employed in a conventional liquid crystal display;

The plan view of Fig. 4 shows the structural layout of the TFT substrate adopted in the liquid crystal panel according to the first embodiment of the present invention;

Fig. 5 is a sectional view taken along the line A-A in Fig. 4;

Fig. 6 is a sectional view taken along the B-B line in Fig. 4;

Fig. 7 is a sectional view taken along the line C-C in Fig. 4;

Figure 8 is a spectrogram of the standard light CIE "C";

Fig. 9 is a spectrum diagram of the light emitted by the white LED;

Figure 10 is a CIE chromaticity diagram showing the range of optimum color reproduction used in television displays and defined by NTSC;

Figure 11 is a spectrum diagram of light emitted from the first three-wavelength light source;

Figure 12 is a spectrum diagram of light emitted from a second three-wavelength light source;

Figures 13A, 13B and 13C are plan views showing the patterns of various color filters within corresponding pixels;

Fig. 14 is a sectional view of a liquid crystal panel according to a second embodiment of the present invention taken along the A-A line in Fig. 4;

Fig. 15 is a sectional view of a liquid crystal panel according to a second embodiment of the present invention taken along the line B-B in Fig. 4;

Fig. 16 is a sectional view of a liquid crystal panel according to a second embodiment of the present invention taken along line C-C in Fig. 4;

Fig. 17A shows the structural layout of the raised part formed under a reflective electrode in the liquid crystal panel of the third embodiment of the present invention, and Fig. 17B is a schematic cross-sectional view of this liquid crystal panel;

Figure 18 is a schematic diagram for explaining the relationship between the width of the raised portion and its height as the width varies;

19A and 19B are schematic diagrams showing a method of making raised portions through two exposure steps;

Figures 20A and 20B are schematic diagrams showing a method of making raised portions by two exposure steps and sequentially showing the processing steps following the steps shown in Figures 19A and 19B;

Figure 21 is a schematic diagram showing a method of making raised portions by two exposure steps and shows the processing steps following the steps shown in Figures 20A and 20B;

Figures 22A and 22B are schematic diagrams showing a method of making raised portions by one exposure step;

Figures 23A and 23B are schematic diagrams showing a method of making raised portions by one exposure step and sequentially showing the processing steps following the steps shown in Figures 22A and 22B;

The block diagram of Fig. 24 shows the structure of a portable information terminal manufactured according to an embodiment of the present invention;

Fig. 25 is a block diagram showing the structure of a portable telephone manufactured according to an embodiment of the present invention.

Detailed ways

A liquid crystal panel, a manufacturing method thereof, and a liquid crystal display using the color liquid crystal panel according to embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 4 is a plan view showing the structural layout of a TFT substrate employed in the liquid crystal panel according to the first embodiment of the present invention. Fig. 5 is a sectional view taken along the A-A line in Fig. 4, Fig. 6 is a sectional view taken along the B-B line in Fig. 4, and Fig. 7 is a sectional view taken along the C-C line in Fig. 4 .

The first embodiment also employs a liquid crystal panel structure similar to that in conventional liquid crystal displays. That is, in the liquid crystal panel structure of the first embodiment, the red pixel 101R, the green pixel 101G, and the blue pixel 101B are arranged in this order along the extending direction of the scanning signal line. One thin film transistor (TFT) 102 is formed in each pixel. The thin film transistor 102 is composed of a gate electrode 103a extending from a gate line 103 serving as a scanning signal line, and a drain electrode 104a extending from a drain line 104 extending in a direction perpendicular to the gate line. Gate lines 103 and gate electrodes 103a are formed on the transparent substrate 100a, and an insulating film 105 is formed on the transparent substrate 100a to cover the gate lines 103 and gate electrodes 103a. Drain line 104 is formed on insulating film 105 . An amorphous silicon layer 106 is formed on the insulating film 105 opposite to the gate electrode 103a, and the drain electrode 104a extends on the amorphous silicon layer 106. In addition, the source electrode 107 protrudes from the amorphous silicon layer 106 in a direction away from the drain electrode 104a, and a part of the source electrode is located at least on and in the amorphous silicon layer.

Furthermore, in the present embodiment, each pixel is divided into, for example, approximately equal two parts, ie, a reflective display part R and a transmissive display part T, by a line extending in a direction parallel to the scanning signal line. In this case, the reflective display portion R is located in a portion including the thin film transistor 102 within the pixel.

In addition, in the reflective display portion R of each pixel, the raised portion 8 is formed on the insulating film 105 . The raised portion 8 is made of, for example, an insulating film. In addition, an insulating film 10 is formed to cover the convex portion 8, the thin film transistor 102, and the like, and a contact hole 11 is also formed in the insulating film 10 to extend to the surface of the source electrode 107. Also, in the reflective display portion R, a reflective electrode 12 is formed within the contact hole 11 and over the insulating film 10 . The reflective electrode 12 has a concave-convex surface reflecting the contour of the convex portion 8 . On the other hand, in the transmissive display portion T, a transparent electrode 9 is formed on the insulating film 10, and the reflective electrode 12 and the transparent electrode 9 overlap each other near the boundary between the reflective display portion R and the transmissive display portion T. In addition, a retardation film 113 and a polarizer 114 are formed on the side of the transparent substrate 100a on which elements such as the thin film transistor 102 are not formed. Each element having the above structure constitutes a TFT substrate.

In addition, there is another transparent substrate 100b placed parallel to the side of the transparent substrate 100a on which the thin film transistor 102 is formed. A color filter (CF) 21 is formed on one side surface of the transparent substrate 100b facing the transparent substrate 100a. As shown in FIGS. 4 to 7, the color filter 21 extends parallel to the drain line 104, and when one pixel is viewed from a direction perpendicular to the surface of the corresponding transparent substrate, the transparent electrode 9 and the reflective electrode 12 are formed on the color filter. within the two end lines of sheet 21. In addition, in the reflective display portion R, there are a plurality of slits 21a in the color filter 21 . The slit 21a is formed to have a width of, for example, 1 μm to 10 μm, and it occupies 50% or less of the area of the color filter 21 in the reflective display portion R. It is to be noted that the ratio of the area occupied by the slit 21a to the area of the color filter 21 in the reflective display portion R can be changed depending on the color to be displayed, and in this embodiment, the slit formed in the green pixel 101G The area ratio occupied by the slit 21 a is, for example, three times the area ratio occupied by the slits 21 a formed in the red pixel 101R and the blue pixel 101B, respectively. In addition, although the slit 21a in this embodiment extends in a direction parallel to the color filter 21, this embodiment is not limited to the slit having the above-mentioned structure, and other patterns having a pattern different from that of the slit 21a may also be used. slit.

In addition, there is a coating layer 25 formed on the transparent substrate 100b to fill the slit 21a while covering the color filter 21, and a counter electrode 122 is formed on the coating layer 25. The coating layer 25 is made of, for example, a transparent resin, and the counter electrode 122 is made of, for example, ITO (Indium Tin Oxide).

A retardation film 123 and a polarizer 124 are also formed on the side of the transparent substrate 100b on which elements such as the color filter 21 are not formed. These elements having the above structure constitute a CF substrate.

Next, liquid crystal 130 is injected between the TFT substrate and the CF substrate.

In the first embodiment having the above structure, in the transmissive display portion T, the light emitted from the backlight (not shown) passes through the color filter 21 to exit to the outside. In the reflective display part R, part of the light that passes through the color filter 21 and reaches the reflective electrode 12 is emitted to the outside through the slit 21a, and part of the light that reaches the reflective electrode 12 through the slit 21a is emitted to the outside through the color filter 21. Also, the following phenomenon can be seen in the reflective display portion R. That is, the light that passes through the color filter 21 and reaches the reflective electrode 12 is emitted to the outside through the color filter 21 , and the light that passes through the slit 21 a and reaches the reflective electrode 12 is emitted to the outside through the slit 21 a. Therefore, when the light emitted from the reflective display part R is input to the inside until it is emitted to the outside, and the time for the light to travel the corresponding distance, the average film thickness of the light to pass through the color filter is approximately equal to that observed in the transmissive display part T. thick. In addition, since in this embodiment, the ratio of the area of the slit 21a to the area of the color filter in the reflective display portion R (hereinafter referred to as "aperture ratio") can be changed according to the color to be displayed, it is possible to make the reflective The color reproduction range of the display portion R and the color reproduction range of the transmissive display portion T coincide with each other according to colors to be displayed. As a result, the liquid crystal display panel constructed as described above can display high-quality images.

Next, the relationship between the aperture ratio and the degree of color balance will be described.

In order to make the above-mentioned relationship clearer, the inventor of the present application has done a simulation in the following manner: first, decide to use a white light-emitting diode (LED) as the backlight; secondly, change the film thickness of the color filter; third, for The aperture ratio is calculated for each film thickness of the color filter so that the chromaticity coordinates of the transmissive display part basically coincide with the chromaticity coordinates of CIE (International Education Center). In this case, standard light CIE "C" is used as light incident to the reflective display portion. Fig. 8 is a spectrum diagram of standard light CIE "C", and Fig. 9 is a spectrum diagram of light emitted from a white LED. It should be noted that the light intensity along the vertical axis in FIGS. 8 and 9 is normalized so that the maximum value of the light intensity takes a value of one. The results obtained by performing the above simulation will be shown in Tables 1 to 7 below.

Table 1

Table 2

table 3

Table 4

table 5

Table 6

Table 7

It should be noted that the NTSC ratio in the table refers to the ratio of the area of the color reproduction range of the corresponding display portion to the area of the color reproduction range which is optimal for TV display and defined by NTSC (National Television System Committee). Figure 10 is a CIE chromaticity diagram showing the color reproduction range most suitable for television display and defined by NTSC.

As shown in Tables 1 to 7 above, in the case where slits are formed in the color filter so that the color filter has an appropriate aperture ratio, the chromaticity coordinates and NTSC ratio calculated for the transmissive display part are the same as those for the reflective The values calculated in the display part are basically the same. On the other hand, in the case where no slit is formed in the color filter in the reflective display part, the chromaticity coordinates and NTSC ratio calculated for the transmissive display part differ greatly from those calculated for the reflective display part . In addition, as shown in Table 5, in the case where slits are formed in the color filter so that the color filter has a fixed aperture ratio in the reflective display portion regardless of the color to be displayed, the color reproduction range of each display portion There is not much difference between them. However, as the color saturation observed in the green pixel increases and the color saturation observed in the red pixel and the blue pixel decreases, the hues observed in the transmissive display part and the reflective display part respectively are different.

In addition, the inventors of the present application carried out the simulation according to the following steps: first, decide to use a three-wavelength light source (the first three-wavelength light source) as the backlight; secondly, change the film thickness of the color filter; third, for the color filter The aperture ratio was calculated for each film thickness of the sheet so that the chromaticity coordinates of the transmissive display portion substantially coincided with the CIE (International Education Center) chromaticity coordinates. In this case, standard light CIE "C" is used as light incident to the reflective display portion. Figure 11 is a graph of the spectrum of light emitted from the first three-wavelength light source. It can be seen that the light intensity along the vertical axis in FIG. 11 is normalized so that the maximum value of the light intensity is taken as 1. The results obtained by performing the above simulation will be shown in Tables 8 to 10 below.

Table 8

Table 9

Table 10

As shown in Tables 8 to 10 above, in the case where slits are formed in the color filter so that the color filter has an appropriate aperture ratio, even if the light source used in the simulation is changed, for the transmissive display part calculated The chromaticity coordinates and NTSC ratios are also basically in agreement with the values calculated for the reflective display part. On the other hand, as shown in Table 9, in the case where the slits are formed in the color filter so that the color filter has a fixed aperture ratio in the reflective display part regardless of the color to be displayed, the color reproduction of each display part The difference between the ranges is not huge. However, as the color saturation observed in the green pixel increases and the color saturation observed in the red pixel and the blue pixel decreases, the hues observed in the transmissive display part and the reflective display part respectively are different.

In the following description, the relationship between the aperture ratio and the light source will be described. When the spectrum of the light emitted from the light source changes, the chromaticity coordinates of the light emitted to the outside through the color filter in the transmissive display part also changes accordingly. The above explanation can also be understood by comparing the numerical values of the corresponding items shown in Table 1 to Table 7 above with the numerical values of the corresponding items shown in Table 8 to Table 10 above. In order to make the relationship between the optimum aperture ratio and the light source clearer, the inventors performed a simulation. In this simulation, the film thickness of the color filter was fixed at 1.6 μm, and the above-mentioned white LED, the first three-wavelength light source, and the additional three-wavelength light source (second three-wavelength light source) were employed as light sources. Figure 12 is a graph of the spectrum of light emitted from the second three-wavelength light source. It can be seen that the light intensity along the vertical axis in FIG. 12 is normalized so that the maximum value of the light intensity is taken as 1. The results obtained by performing the above simulations are shown in the following Tables 11 to 13 representing the cases of using white LEDs, the first three-wavelength light source, and the second three-wavelength light source, respectively.

Table 11

Table 12

Table 13

As shown in Table 13, in the case of using the second three-wavelength light source in the simulation, the best range of color reproduction can be obtained when the aperture ratios applied to the red and green filters are consistent with each other.

The results obtained in these simulations tell us that no matter what light source is used in the simulation, the aperture ratio applied to the green filter should be the largest of the three aperture ratios applied to the red, green, and blue filters . Specifically, in the case of using a white light source in the simulation, it is preferable to make the aperture ratio applied to the green color filter two to four times that applied to the red and blue color filters.

It should be noted that the width of the slits of the color filter is preferably between 1 μm and 10 μm. When the width of the slit is narrower than 1 [mu]m, the operation of forming a corresponding pattern in the color filter becomes very difficult. On the other hand, when the width of the slit is wider than 10 µm, the operation of leveling the coating layer formed on the color filter becomes very difficult.

As already mentioned in the above description, the openings of the color filter are not limited to the above-mentioned slits, and other openings having patterns different from the slits may also be used. In addition, the relative positional relationship between the reflective display part and the transmissive display part is not limited to the above-mentioned structure of the reflective display part and the transmissive display part.

13A, 13B and 13C are plan views showing the patterns of various color filters within a pixel and the positional relationship between the reflective display portion and the transmissive display portion.

For example, as shown in FIG. 13A, in the case where the reflective display portion R and the transmissive display portion T are separated as in the above-mentioned embodiment, the liquid crystal panel of the present invention may be formed in a color filter 41 and be used. An opening 41a is placed at the center of the reflective display portion R. As shown in FIG.

In addition, as shown in FIG. 13B, in the case where the reflective display portion R and the transmissive display portion T are separated so that the reflective display portion R is surrounded by the transmissive display portion T, the liquid crystal panel of the present invention may employ color filters formed on 42 and is placed in the central opening 42a of the reflective display portion R.

In addition, as shown in FIG. 13C, in the case where the reflective display portion R and the transmissive display portion T are separated so that the transmissive display portion T is inserted between the two reflective display portions R, the liquid crystal panel of the present invention can adopt the following pixel structure. That is, the pixel is constructed such that the end line 43a of the color filter 43 is positioned closer to the transmissive display portion T than the outer end lines of the two reflective display portions R, thereby forming a plurality of color filters 43 in the pixel in which no color filter 43 is formed. Area.

It should be noted that regardless of the pattern of the color filter, it is preferable to make the ratio of the opening area to the area of the reflective display portion equal to or less than 50%. In other words, the color filter needs to be formed to occupy at least 50% of the entire area of the reflective display portion. The reason for this is as follows. That is, when the color filter occupies less than 50% of the entire area of the reflective display part, there is no chance for a period of time (during which light travels a corresponding distance from being input to the inside until it exits to the outside) to pass through. The ratio of the light filtered by the color filter to the total light on the reflective display portion increases, making it difficult to match the color reproduction range of the reflective display portion to that of the transmissive display portion.

A second embodiment of the present invention will be described below. In the second embodiment, the film thickness of the color filter in the transmissive display portion is thinner than that of the color filter in the transmissive display portion. 14, 15 and 16 are cross-sectional views showing the structure of a liquid crystal panel according to a second embodiment of the present invention taken along lines A-A, line B-B and line C-C in FIG. 4, respectively. It can be seen that the parts and elements used in the second and second embodiments shown in Figures 14, 15 and 16 are also used in the first embodiment shown in Figures 4, 5, 6, 7 and 8, Also, they have the same reference numerals as in the first embodiment, so a detailed description thereof will be omitted.

The second embodiment also includes the following structure of the liquid crystal panel similar to that of the first embodiment. That is, the liquid crystal panel of the second embodiment is constructed such that each pixel thereof is divided into, for example, two approximately equal parts by a line extending in a direction parallel to the scanning signal line, that is, the reflective display portion R and a transmissive display portion T. In addition, the TFT substrate is also constructed in the same manner as in the first embodiment.

The CF substrate in the second embodiment is configured such that the color filter 51 is formed on one surface of the transparent substrate 100b facing the transparent substrate 100a. In addition, in the reflective display portion R, a transparent resin layer 52 is formed between the color filter 51 and the transparent substrate 100b. In this case, the ratio of the volume of the transparent resin layer 52 to the entire volume of the color filter 51 and the transparent resin layer 52 in the reflective display portion R (hereinafter this ratio will be referred to as "volume ratio") is set as (for example ) between 35% and 65%. This volume ratio can be adjusted by changing the film thickness or area of the transparent resin layer 52 . It can be seen that the volume ratio varies according to the color to be displayed, and in this embodiment, the volume ratio applied to the green pixel 101G is about three times the volume ratio applied to the red pixel 101R and the blue pixel 101B. In addition, although the transparent resin layer 52 is formed to completely cover the color filter 51 in the present embodiment, the present embodiment is not limited to the above-described structure of the transparent resin layer and the color filter. It may also be satisfactory for the color filter 51 to have a flat surface in the same plane on two regions corresponding to the reflective display portion R and the transmissive display portion T.

In the liquid crystal panel of the second embodiment constructed as above, in the transmissive display portion T, the light emitted from the backlight (not shown) is emitted to the outside through the color filter 51 . In the reflective display portion R, the light reaching the reflective electrode 12 through the color filter 51 passes through the color filter 51 to exit to the outside. In this case, since the film thickness of the color filter 51 in the reflective display part R is made to be about half of the film thickness of the color filter 51 in the transmissive display part T, light passes through the corresponding distance from input to the inside until it exits to the outside. The actual film thickness of the color filter through which the light passes is approximately equal to the film thickness observed from the transmission display portion T within the time of the distance. In addition, in this embodiment, since the volume ratio calculated for the volume of the transparent resin layer 52 varies with the color to be displayed, it is possible to make the color reproduction range of the reflective display part R and the color reproduction range of the transmissive display part T consistent with each other, thereby allowing the liquid crystal panel to display high-quality images.

Next, the relationship between the volume ratio and the degree of color balance will be described. The inventor of the present application made the above-mentioned relationship clearer by a simulation similar to that in the first embodiment: at first, decided to use a three-wavelength light source (the first three-wavelength light source) as the backlight; secondly, changed the color filter The film thickness and the area of the transparent resin layer are changed at the same time; third, the volume ratio is calculated according to each film thickness of the color filter to obtain the chromaticity coordinates of the transmission display part and the CIE (International Education Center) chromaticity coordinates. matching values. In this case, standard light CIE "C" is used as light incident to the reflective display portion. The results obtained by performing the above simulation will be shown in Tables 14 to 15 below.

Table 14

Table 15

It should be noted that the "area ratio" in the above table indicates the ratio of the area of the transparent resin layer to the area of the color filter in the reflective display section, and the "volume ratio" in the above table indicates the volume of the transparent resin layer to the reflective area. Displays the ratio of the entire volume of the color filter to the transparent resin layer in the part. In addition, "film thickness" means the film thickness of the color filter in the transmissive display section, which corresponds to the overall film thickness of the color filter and the transparent resin layer in the reflective display section.

As shown in Tables 14 and 15 above, in the case where the transparent resin layer is formed in the reflective display part and has an appropriate volume ratio, the chromaticity coordinates and NTSC ratios calculated for the transmissive display part are the same as those calculated for the reflective display part. The results are basically consistent.

A method for manufacturing the liquid crystal panel according to the first embodiment of the present invention will be described below. The TFT substrate can be manufactured using the same method as that used to manufacture conventional liquid crystal panels. On the other hand, the CF substrate can be produced by, for example, the following method: first, a layer of photosensitive resin film is coated on the transparent substrate 100b as a source material film constituting a monochromatic color filter; A photomask with a slit pattern is used to expose the photosensitive resin film, and then the photosensitive resin film is developed. Through these steps, the photosensitive resin film is patterned to form a monochromatic color filter 21 having slits 21a. These steps described above are performed to form three kinds of color filters 21 respectively. It should be noted that, for example, when a green color filter is formed using a photomask, the ratio of the area of the pattern to be formed on the photomask corresponding to the slits to the area of the photomask is the largest. That is, the ratios applied to the corresponding color filters can be adjusted independently. In other words, the photomask is separately formed to have a pattern corresponding to the slit pattern formed in the color filter and corresponding to a color to be displayed. In the case of using a white light source in a liquid crystal display, it is preferable to make the ratio of the area of the slit pattern to the area of the photomask used to form the green color filter to be about The mask is applied two to four times the area ratio.

After the three kinds of color filters are formed, a cover layer is formed on the entire surface of the transparent substrate 100b while flattening, and an opposite electrode is also formed thereon. In addition, a retardation film and a polarizer are formed on the side of the transparent substrate 100b where no color filter is formed.

A method for manufacturing a liquid crystal panel according to a second embodiment of the present invention will be described below. The TFT substrate can be manufactured using the same method as that used to manufacture conventional liquid crystal panels. On the other hand, the CF substrate can be produced by, for example, the following method: First, photomasks are prepared in advance in such a manner that each photomask formed corresponding to the color to be displayed has an The pattern corresponding to the pattern; second, coating the raw material constituting the transparent resin film on the transparent substrate 100b; third, using the above-mentioned photomask to form a corresponding pattern in the raw material film, and then forming the transparent resin film on the transparent substrate 100b 52; fourthly, coating another layer of raw material film constituting the color filter on the transparent substrate 100b, and then performing corresponding processing steps, for example, exposing and developing another layer of raw material film to form a color filter, thereby Make it a flat surface corresponding to the color to be displayed. It should be noted that when the green color filter is formed using a photomask, the ratio of the area of the pattern formed in the photomask and corresponding to the transparent resin film to the area of the photomask is the largest. That is, the ratios applied to the corresponding color filters can be adjusted independently. In other words, the photomask is individually formed to have a pattern corresponding to the pattern of the transparent resin film and the color to be displayed. In the case of using a white light source in a liquid crystal display, it is preferable to make the ratio of the area of the pattern formed in the photomask to the area of the photomask used to form the green color filter approximately equal to that used for forming the red or blue color filter. Color filters should be applied two to four times the area ratio of the photomask.

After the three kinds of color filters are formed, a cover layer is formed on the entire surface of the transparent substrate 100b while also achieving flatness, and an opposite electrode is also formed thereon. In addition, a retardation film and a polarizer are formed on the backside surface of the transparent substrate 100b where no color filter is formed.

It should be noted that although the liquid crystal panels used in the first and second embodiments do not contain a black matrix between the adjacent color filters of the CF substrate, the liquid crystal panel can also be made so that the adjacent color filters of the CF substrate A black matrix is formed between them. In addition, although the liquid crystal panels used in the first and second embodiments have a color filter formed on the transparent substrate on which the thin film transistor is not formed, the liquid crystal panel may also be formed so that the color filter is formed on it. A substrate on which thin film transistors are formed. In this case, a color filter is formed on, for example, a reflective electrode or a transparent electrode.

A third embodiment of the present invention will be described below. An object of the third embodiment is to provide a liquid crystal display in which the chromaticity of colors is improved. FIG. 17A shows the structural layout of the protrusions formed under the reflective electrodes in the liquid crystal panel of the third embodiment of the present invention, and FIG. 17B is a schematic cross-sectional view of such a liquid crystal panel.

In the first and second embodiments, the convex portions 8 are formed in various directions below the reflective electrode so that the reflective electrode has a concave-convex surface reflecting the contour of the convex portion. In this embodiment, in addition to the raised portion 8, the raised portion 58 formed in the same step of forming the raised portion 8 is formed between adjacent pixels along the direction in which the scanning signal line (gate line) extends. within the border area. The width and height of the raised portion 58 are substantially the same as those of the raised portion 8 .

According to the third embodiment constituted as above, as shown in FIG. 17B, the gap "d1" between the color filter 21 and the insulating film 10 under the reflective electrode in the pixel and the transparent substrate 100b and the boundary between the pixels are The difference between the gaps "d2" between the insulating films 10 in the region is made shorter than that observed in conventional liquid crystal panels. More specifically, in the conventional liquid crystal panel, since there is an undesired border area (wherein the convex portion 108 is not formed) in the border area between pixels, it is different from the present embodiment (where there is no such undesirable The gap between the undesired interface region and the transparent substrate 100b appears particularly large compared to the gap observed in the interface region of . According to the liquid crystal panel in this embodiment, an image exhibiting a yellowish color can be substantially eliminated from display.

It should be noted that, assuming that the width of the raised portion 58 is W1 and the width of the raised portion 8 is W2, the raised portion 58 and the raised portion 8 preferably satisfy the following formula:

(W2-1)≤W1≤(W2+1) (unit: μm)

In addition, it is better if the raised portion 58 and the raised portion 8 can satisfy the following formula:

(W2-0.5)≤W1≤(W2+0.5) (unit: μm)

FIG. 18 is a schematic diagram for explaining the relationship between the width of a raised portion and its height as a function of the width. In the case where "W2" is made longer than "W1", the difference between the surface tensions of the raised parts 8 and 58 when the raised parts undergo heat treatment (the material is liquefied by baking) in the corresponding manufacturing step The material constituting raised portion 8 will flow into raised portion 58 in the direction of arrow "A". As a result, the height of the raised portion 58 becomes longer than the designed value, and the height of the raised portion 8 becomes shorter than the designed value. On the contrary, in the case where "W2" is made shorter than "W1", the height of the convex portion 58 becomes shorter than the design value, and the height of the convex portion 8 becomes longer than the design value, thereby making Efforts to eliminate the difference between the gaps "d1" and "d2" become impossible. Therefore, it is necessary to design the values of "W1" and "W2" to be substantially equal, and at the same time, it is necessary to ensure the margin in the above formula. It can be seen that if the cross-sectional view shown in FIG. 17B is drawn accurately to correspond to FIG. 17A, the raised portion 8 should also be drawn in FIG. 17B. However, for convenience, in the sectional view shown in FIG. 17B, the raised portion 8 is omitted, and only the raised portion 58 is shown. In addition, those skilled in the art should understand that the liquid crystal panel shown in FIG. 14 and FIG. 16 is also constructed according to the above-mentioned content, that is, except for the raised portion 8, there is also the same width as the raised portion 8 and height of the raised portion 58 .

Hereinafter, a method of manufacturing the convex portion under the reflective electrode by using a single-layer photosensitive resin film will be described. First, a method of manufacturing a raised portion by two exposure steps will be described, and then a method of manufacturing a raised portion by one exposure step will be described. 19A, 19B, 20A, 20B, and 21 are schematic diagrams sequentially showing a method for manufacturing a raised portion by two exposure steps.

First, as shown in FIG. 19A, after forming TFTs (not shown) and the like, a resist film 71 made of a photosensitive resin is coated on a transparent substrate 100a. Before the above-mentioned smearing operation is completed, a photomask 72 is prepared in such a manner that a Cr thin film 73 is formed on a transparent substrate 74, which can prevent light from incident on the resist film 71 corresponding to the raised portion. on the corresponding part.

Next, as shown in FIG. 19B , the resist film 71 made of a photosensitive resin is exposed using a photomask 72 to form an exposed portion 71 a in the resist film 71 . In this case, the exposure depth is preferably limited to, for example, a position down from the surface of the resist film to about half of the film thickness of the resist film 71 made of photosensitive resin.

After that, as shown in FIG. 20A, a photomask 75 is prepared in such a manner that a Cr thin film 76 is formed on a transparent substrate 74 with a Cr film in a portion corresponding to the contact hole 11. Open your mouth. Then, the photomask 75 is used to expose the resist film 71 made of photosensitive resin, so that another exposed portion 71a is formed on the resist film 71, which is in contact with the part of the resist film where the contact hole 11 will be formed later. The positions correspond and reach the surface of the source electrode (not shown).

Then, as shown in FIG. 20B, the resist film is developed to remove the exposed portion 71a.

Next, as shown in FIG. 21 , the resist film 71 made of photosensitive resin is baked so as to flow around the steps existing on the surface of the resist film 71 made of photosensitive resin. As a result, raised portions and contact holes 11 are formed.

Next, a method of manufacturing convex portions by one exposure step will be described. 22A, 22B, 23A, and 23B are schematic diagrams sequentially showing a method for manufacturing a convex portion by one exposure step.

First, as shown in FIG. 22A, after forming TFTs (not shown), a resist film 71 made of a photosensitive resin is coated on a transparent substrate 100a. Before the above-mentioned smearing operation is completed, a photomask 82 is prepared in such a manner that a translucent film 83 is formed on a transparent substrate 84 with an opening only in a portion corresponding to the contact hole 11 in the film. , and a Cr thin film 85 is formed on the translucent thin film at a position corresponding to the raised portion, which can prevent light from incident on the resist film 71. In this case, the translucent thin film 83 is composed of, for example, a metal oxide film.

Next, as shown in FIG. 22B, the resist film 71 made of a photosensitive resin is exposed to light using a photomask 82 to form an exposed portion 71b. In this case, the exposure depth is preferably limited to, for example, a position down from the surface of the resist film to about half of the film thickness of the resist film 71 made of photosensitive resin. As a result, exposed portions 71b are formed in the resist film 71 made of photosensitive resin. A portion of the exposed portion 71b corresponding to the contact hole 11 can directly receive exposure without passing through the translucent film 83, and therefore, the exposure depth is located near the surface of the source electrode (not shown).

After that, as shown in FIG. 23A, the resist film is developed to remove the exposed portion 71b.

Next, as shown in FIG. 23B , the resist film 71 made of photosensitive resin is baked so as to flow around the steps existing on the surface of the resist film 71 made of photosensitive resin. As a result, raised portions and contact holes 11 are formed.

It should be noted that although a resist film made of a photosensitive resin is used to form the raised portion in this embodiment, instead, this embodiment may employ the following method to manufacture the raised portion. That is, for example, a plurality of convex portions made of an insulating film are formed, and another insulating film is formed thereon to cover the entire thin film of the above-mentioned insulating film, thereby forming a concavo-convex in the pixel and in the boundary between pixels. surface.

In addition, it is also possible to construct the liquid crystal panel according to the present invention by combining the structure of the liquid crystal panel adopted in one of the first and second embodiments with the structure of the liquid crystal panel adopted in the third embodiment. .

The liquid crystal panel manufactured according to the above embodiments can be applied to, for example, displays of portable information terminals, portable phones, portable personal computers, notebook computers, or desktop personal computers. Fig. 24 is a block diagram showing the structure of a portable information terminal manufactured according to an embodiment of the present invention. In addition, Fig. 25 is a block diagram showing the structure of a portable telephone manufactured according to the embodiment of the present invention.

The portable information terminal 250 manufactured according to the embodiment of the present invention includes a display unit 268 composed of a liquid crystal panel 265, a backlight unit 266 and an image signal processing unit 267 for processing image signals. In addition, the portable information terminal 250 also includes: a control unit 269, which is used to control the various components of the portable information terminal 250; a storage unit 271, which is used to store programs and various data executed by the control unit 269; a communication unit 272, which uses For data transmission and data reception with external devices; input unit 273, which includes, for example, a keyboard or a pointing device; It can be seen that the above-mentioned second and third embodiments are applied to the liquid crystal panel 265 .

The portable information terminal 250 having the structure described in the embodiment of the present invention can display a high-quality image by producing a color-balanced visible image or suppressing buff in the color.

A portable telephone 275 having the structure described in the embodiment of the present invention includes a display unit 276 composed of a liquid crystal panel 265, a backlight unit 266, and an image signal processing unit 267 for processing image signals. In addition, the portable phone 275 also contains: a control unit 277, which is used to control the various components of the portable phone 275; a storage unit 278, which is used to store programs and various data executed by the control unit 277; a transmitting unit 281, which uses for transmitting wireless signals to external devices; an input unit 282, which includes, for example, a keyboard or a pointing device; It can be seen that the above-mentioned first, second and third embodiments are applied to the liquid crystal panel 265 .

The portable telephone 275 having the structure according to the embodiment of the present invention is also capable of displaying high-quality images by producing color-balanced visual images or suppressing yellowish tints in colors.

As described above, according to the first to sixth technical solutions of the present invention, since an opening whose occupied area can be changed according to the color to be displayed is formed in the color filter, and only one filter color is formed corresponding to each pixel Therefore, the liquid crystal panel according to the present invention can make the color reproduction ranges of the reflective display part and the transmissive display part in each pixel substantially consistent with each other. This structure of the liquid crystal panel allows the liquid crystal panel to realize the display of high-quality images without increasing its manufacturing process steps. Specifically, in the case where the aperture ratio applied to the color filter for displaying green with high visibility is the largest, the difference in the color reproduction range of the reflective display portion and the transmissive display portion can be further reduced. In addition, according to the seventh aspect of the present invention, since the gap between the substrates inserted into the liquid crystal is narrowed, the light yellow color observed in the conventional liquid crystal panel can be reduced.

In addition, according to the methods described in the eighth and ninth aspects of the present invention, it is possible to manufacture a color liquid crystal panel having the above advantages in terms of the structure of the color filter.

In addition, according to the tenth technical solution of the present invention, the color liquid crystal panel having the above advantages in terms of color filter structure can be applied to a color liquid crystal display.

Claims (2)

1. A color liquid crystal panel, comprising: transparent substrate; A thin film transistor formed in each pixel on the transparent substrate; an insulating film formed on the above-mentioned transparent substrate and having a concave-convex surface in each of the above-mentioned pixels; a reflective electrode formed on the above-mentioned insulating film and connected to the above-mentioned thin film transistor in each of the above-mentioned pixels, In the above-mentioned color liquid crystal panel, the above-mentioned insulating film has a plurality of raised portions, each of which extends along the boundary between adjacent pixels, and the width of each raised portion is the same as that of the concave-convex surface constituting each of the above-mentioned pixels. The width of the convex part is equal. 2. A color liquid crystal display, characterized in that it has a liquid crystal panel constructed according to claim 1.

Images