JP5306138B2 - Color liquid crystal display element - Google Patents

Description

  The present invention relates to a color liquid crystal display element incorporating a color filter.

  In a liquid crystal display device that performs full-dot color display, as shown in Patent Document 1, each picture element (pixel) is divided into three pixels (sub-pixels), and red (R), green (G), blue ( A color liquid crystal display panel is used in which color element pieces constituting a color filter corresponding to the three primary colors B) are arranged for each sub-pixel. In a color liquid crystal display panel, a black mask that blocks light from surrounding areas of the display area (hereinafter referred to as a frame area) and subpixels in the display area in order to prevent light leakage and light color mixing between the color filters. Is provided. This black mask is usually manufactured using a photoresist resin material containing a black pigment or the like.

  In the above-described liquid crystal display device, when an image is displayed on the color liquid crystal display panel, display unevenness may occur around the display area of the color liquid crystal display panel. This is because the display area and the frame area around the display area on the surface of the flattening protective layer that is deposited by covering each color element piece of the color filter after disposing each color element piece in the opening of the black mask formed on the substrate. This is because an uneven portion having a non-uniform height occurs in the vicinity of the boundary.

  Specifically, the display area has an overlapping portion of the color filter that protrudes from the sub-pixels onto the black mask, and accordingly, the height of the leveling protective layer in the display area is increased accordingly. In the vicinity of the boundary between the display area and the frame area, an inclined portion is generated in which the height of the planarization protective layer decreases from the display area toward the frame area.

  Retardation (light phase difference), which is a factor relating to the hue of light transmitted through the liquid crystal layer, is expressed by the product Δn · d of the refractive index anisotropy Δn of the transmitted light and the liquid crystal layer thickness d. Therefore, the uneven height of the planarization protective layer means that the thickness of the liquid crystal layer becomes non-uniform, which causes variations in the retardation of transmitted light and causes display unevenness.

  Therefore, as shown in Patent Document 2, a color liquid crystal display device has been proposed in which the protrusion of the color filter to the black mask between the sub-pixels, which is a factor for increasing the height of the planarization protective layer, is eliminated.

JP 2006-337590 A JP-A-8-327999

  However, even if the protrusion of the color filter to the black mask between the sub-pixels is eliminated as shown in Patent Document 2, display unevenness may occur around the display area.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a color liquid crystal display element in which the liquid crystal layer thickness is reliably uniform over the entire display area and display unevenness does not occur around the display area regardless of the arrangement structure of the color filter. That is.

The color liquid crystal display element according to claim 1 of the present invention is disposed on the viewing side of the display and has a first substrate on which a first electrode is formed, and an electrode forming surface of the first substrate. A second substrate disposed oppositely and having a second electrode formed on the opposing surface; a liquid crystal layer sandwiched between the opposing electrode forming surfaces of the first substrate and the second substrate; A color filter disposed on either the first substrate or the second substrate so as to correspond to a plurality of pixels formed in a facing portion between the first electrode and the second electrode, and at least , A light shielding film disposed in a peripheral portion surrounding a display region in which color filters are disposed corresponding to a plurality of pixels, and a boundary between the display region and the peripheral portion on the light shielding film in the peripheral portion The color along the boundary line at a position separated from the line by a predetermined distance. It has a dummy color filters arranged in the same material as the filter, the light-shielding film, the color filter, and a flattening protective film is deposited and formed over the dummy color filter, the dummy color filter and Each color element piece constituting the color filter is formed in the same rectangle, and the distance for separating the dummy color filter from the boundary line is 2 of the width of one pixel in the arrangement direction of the first electrode. doubled, in the arrangement direction of the second electrode to the length of one pixel and is characterized that you have been set respectively.

According to a second aspect of the present invention, in the color liquid crystal display element according to the first aspect, the light shielding film is a resin black mask.

According to a third aspect of the present invention, in the color liquid crystal display element according to the first or second aspect , the light shielding film is also disposed between the pixels in the display region, and each color element piece of the color filter is shielded from light. It is characterized by being filled and installed without protruding into a pixel space partitioned by a film.

  According to the present invention, there is provided a color liquid crystal display element in which the thickness of the liquid crystal layer is made uniform over the boundary line from the display area to the frame area, and no frame-like display unevenness occurs around the display area. can get.

It is a top view which shows the color liquid crystal display element as one Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. FIG. 5 is a plan view showing a mask used for manufacturing the color liquid crystal display element, where (a) shows a mask used for manufacturing a black mask, and (b) shows a mask used for manufacturing a color filter. Yes. (a) is an enlarged explanatory view exaggeratingly showing the shape of the surface of the flattening protective layer in the vicinity of the boundary between the display region and the frame region in the color liquid crystal display element as one embodiment of the present invention, (b) These are the expansion explanatory views corresponding to (a) in the color liquid crystal display element as a comparative example. FIG. 7 is an enlarged explanatory view exaggeratingly showing the shape of the surface of the planarization protective layer in the vicinity of the boundary between the display region and the frame region in a conventional color liquid crystal display element, and (a) shows an empty cell state before liquid crystal injection. (B) shows the state after liquid crystal injection.

  The color liquid crystal display element of the present embodiment is a simple matrix type STN (Super Twisted Nematic) type color liquid crystal display element. As shown in FIG. A plurality of striped scanning electrodes 3 are laid in parallel to each other on the inner surface (opposite surface) of the front glass substrate 1 positioned on the display viewing side. The scanning electrode 3 is made of a transparent conductive film such as ITO (indium tin oxide) having a thickness of about 0.2 μm. A pre-alignment film 4 made of a transparent insulating resin material such as polyimide resin is uniformly applied over the entire surface so as to cover the scanning electrodes 3.

  On the other hand, a black mask 5 as a light shielding film is laminated on the inner surface of the rear glass substrate 2 disposed on the side opposite to the front glass substrate 1 (the back side of the display). The black mask 5 is made of a positive type photoresist resin containing a black pigment such as carbon black, and is formed to a thickness of about 1.4 μm by photolithography using a mask plate M5 as shown in FIG. The pattern is formed. Thus, by forming the black mask 5 from a resin material, a black mask having a pattern in which a plurality of openings M51 are arranged in a matrix can be easily manufactured with a small number of man-hours.

  The openings 51 formed in the black mask 5 in a matrix arrangement define one pixel space, and each of the openings 51 has red, green, and blue color element pieces 6R, 6G, 6B is filled and installed in a predetermined arrangement. In the present embodiment, rows Rr, Rg, Rb of color pixels (subpixels) Pr, Pg, Pb formed by filling the black mask opening 51 with the color element pieces 6R, 6G, 6B are arranged in order. Stripe arrangement is adopted. That is, each color pixel (sub-pixel) Pr, Pg, Pb is sequentially arranged and arranged in the row direction X of the display area D1 in which the rectangular outer shape in which the rectangular color pixels Pr, Pg, Pb are arranged in a matrix form a rectangle. Color pixels (subpixels) Pr, Pg, and Pb having the same color as Y are arranged in one row.

  Here, each color element piece 6R, 6G, 6B is filled to a thickness of about 1.3 μm without protruding into each corresponding opening 51. Therefore, the surface of the black mask 5 is filled with each color element piece 6R. , 6G, 6B, the substantially entire area from the display area D1 in which the openings 51 are arranged in a matrix to the frame area D2 of only the black mask material around it is a substantially flat surface.

  The color filter 6 having a stripe arrangement without protruding color elements as described above is formed by photolithography using a mask plate M6 for producing a color filter shown in FIG. Using a mask plate M6 in which a plurality of rows of openings M61 aligned with the openings M51 arranged in a row of the black mask manufacturing mask plate M5 shown in FIG. For each color, the mask plate M6 is accurately shifted by one row pitch of the openings 51 of the black mask, and the respective color element pieces 6R, 6G, 6B are filled in the corresponding openings 51, whereby it can be easily manufactured. According to this method, since one mask M6 is shared by each color, the cost is reduced accordingly. The method for filling and installing the color element pieces 6R, 6G, 6B is not limited to photolithography, and a thermal transfer method or the like is also preferably used.

  As shown in FIG. 1, a dummy color filter 7 is provided in an area corresponding to the frame area D2 of the black mask 5, that is, a peripheral area where the color filter color element pieces 6R, 6G, and 6B are not provided with openings. It is arranged. The dummy color filter 7 of this embodiment is composed of three types of dummy color element pieces 7R, 7G, and 7B of red, green, and blue, like the color filter 6 of the display area D1, and includes a display area D1 and a frame area D2. The frame is separated from the boundary line L by a predetermined distance C, and is disposed along the boundary line L over substantially the entire circumference of the frame region D2.

  The dummy color filter 7 of the present embodiment is a pair of dummy color filters in which red, green, and blue dummy color element pieces 7R, 7G, and 7B are sequentially arranged in a pair of areas parallel to the row direction X of the frame region D2. A pair of dummy color filter columns 72 in which three columns of dummy color element pieces 7R, 7G, and 7B of the same color are arranged in parallel in the column direction Y one by one in a row 71 and a pair of areas parallel to the column direction Y, respectively. And is composed of.

  Here, the separation distance C from the boundary line L of the dummy color filter 7 is the separation distance Cy from the dummy color filter row 71 arranged in one row in the row direction X and the boundary line L is one pixel p forming a rectangle. Is set to a distance (a + 2c) obtained by adding a pair of pixel gaps 2c to the length a. The distance Cx between the dummy color filter rows 72 arranged in three rows in the column direction and the boundary line L is a distance (2b + c) obtained by adding a pixel gap c to a width 2b of two rows of pixels p having a width b. ) Is set.

  When the dummy color filter 7 is manufactured, the mask M6 for forming the color filter 6 is used, and the dummy color filter 7 is formed by a photolithography method in the same process.

Therefore, as shown in FIG. 3B, the color filter manufacturing mask M 6 is provided with dummy color filter openings M 62 corresponding to the arrangement of the dummy color filters 7. That is, a plurality of row-direction openings M62 are formed in one column in the row direction X with a width 2b of two pixels and a three- fold pixel gap 3c in correspondence with each of the pair of dummy color filter rows 71 (see FIG. 1). A plurality of column-direction openings M62 are formed in one column in the column direction Y so as to correspond to the pair of dummy color filter columns 72, respectively.

  In the manufacturing process of the color filter, when the formation of each red color element piece is completed, the above-described mask M6 is shifted in the row direction X by one pixel column pitch, and then a green color element piece is formed. When the formation of the color element pieces is completed, the mask M6 is similarly shifted in the row direction X by one pixel column pitch to form the blue color element pieces. In this way, the color filter 6 and the dummy color filter 7 can be simultaneously formed with a small number of man-hours by a simple mask operation in which one color filter mask M6 is shifted by a predetermined pitch.

  As shown in FIG. 2, a transparent flattening protective film 8 is deposited on substantially the entire black mask 5 covering the color filter 6 and the dummy color filter 7 and extending from the display area D1 to the frame area D2. The planarization protective film 8 of the present embodiment is formed by coating with a thickness of about 2 μm using an acrylic resin as a material by a printing method.

On the surface of the flattening protective film 8, a plurality of display electrodes 9 are laid in parallel to a direction perpendicular to the scanning electrodes 3, and a rear alignment film 11 is deposited so as to cover these display electrodes 9. . The display electrode 9 and the rear alignment film 11 are also formed by the same method using the same material as the scan electrode 3 and the front alignment film 4 described above.

  The above-described rear glass substrate 2 and the above-described front glass substrate 1 are bonded to each other with a predetermined gap by a sealing material 12 with their electrode forming surfaces (inner surfaces) facing each other. Between these substrates, a large number of spherical gap members 13 are evenly dispersed, and the gap between the front and rear glass substrates 1 and 2 is maintained at a size corresponding to the particle size of the gap member 13. Has been.

  In a cell space surrounded by the sealing material 12 and the front and rear glass substrates 1 and 2, liquid crystal 14 is injected and sealed by a well-known vacuum injection method, for example. Since the color liquid crystal display element of this embodiment is an STN type, nematic liquid crystal having a large twist alignment angle of liquid crystal molecules of about 280 ° is enclosed.

  In the color liquid crystal display element of the present embodiment formed as described above, as shown in FIG. 4A, the surface of the rear alignment film 11 above the arrangement area corresponding to the dummy color filter 7 is raised. ing. Here, since the separation distance C is secured between the dummy color filter 7 and the display area D1 as described above, the raised surface above the dummy color filter 7 and the color filter 6 above the area of the separation distance C. The level difference G1 with the flat surface is substantially eliminated, and a flat surface is secured over the entire area as long as it is limited to the display area D1.

  As a result, a liquid crystal layer 14 having a uniform layer thickness sandwiched by the flat surfaces of the alignment films 4 and 11 is obtained over the entire display region D1, and particularly around the periphery of the display region D1 that is likely to occur in STN type color liquid crystal display elements. Occurrence of frame-shaped display unevenness along the line is reliably prevented.

  Here, the reason why the arrangement configuration of the dummy color filter 7 according to the present invention is effective in obtaining the above-described effect will be described.

  First, when the dummy color filter 7 is removed from the color liquid crystal display element of the present embodiment, as shown in FIG. 5A, the area corresponding to the display area D1 of the black mask 5 is formed in a matrix arrangement. Each color element 6R, 6G, 6B constituting the color filter 6 is filled in the opening 51 without protruding, and the front surface of the black mask 5 between the color elements 6R, 6G, 6B slightly protrudes (about 0.1 μm). It is almost flat. Therefore, the surface of the black mask 5 is substantially flat over the entire area.

  However, the surface of the alignment film 11 covering the flattening protective film 8 deposited on the surface of the flat black mask 5 and the display electrode 9 formed thereon has a boundary line as shown in FIG. Irregularities occur in the vicinity of L. The unevenness is caused by the difference in surface tension between the resin materials forming the color filter 6, the black mask 5, and the planarization protective film 8.

  In the present embodiment, an acrylic resin in which carbon black is dispersed is used as the material for the black mask 5, a phthalocyanine-based organic pigment-dispersed acrylic resin is used as the material for the color filter 6, and an acrylic resin is used as the material for the planarization protective film 8. The contact angle of the flattening protective film 8 material with respect to the color filter 6 material is smaller than the contact angle of the flattening protective film 8 material with respect to the black mask 5 material. That is, the planarization protective film 8 material has better wettability (affinity) with respect to the color filter 6 material than with the black mask 5 material. Therefore, the material for the flattening protective film 8 is drawn toward the black mask 5 material side, that is, the frame region D2 side of the black mask 5 without the color filter 6, and this causes the boundary as shown in FIG. Unevenness is generated from the line L to the frame area D2 side.

  In order to inject liquid crystal into the cell space by vacuum injection, the inside of the cell is once depressurized and then the external pressure is released to the atmosphere, and then the liquid crystal is injected. However, the recess 111 of the alignment film 11 described above is supported by the cap material 13. Since it is not floated, when it is suddenly pressurized from the outside due to release to the atmosphere, the gap is locally narrowed as shown in FIG. As a result, the thickness of the liquid crystal layer in the vicinity of the boundary line L becomes thin, and this causes a display unevenness (frame unevenness) along the boundary line L.

In order to eliminate the unevenness on the surface of the post-alignment film 11 described above, when the dummy color filter 7 is disposed without being spaced from the boundary line L as shown in FIG. Since a step G2 between the raised surface of the portion covering the color filter 7 and the flat surface of the portion covering the color filter 6 occurs in the display area D1, the step G2 causes a frame unevenness along the inner side of the boundary line L. It becomes.

For the above-described reason, as shown in FIG. 4A, the flatness of the liquid crystal sandwiching surface in the display region D1 is achieved by separating the arrangement position of the dummy color filter 7 from the boundary line L by a predetermined distance C. As a result, the occurrence of unevenness in the frame is reliably prevented. Here, the separation distances Cx and Cy in each direction are not limited to the dimensions described above, but the height of the dummy color filter 7, the material properties of the flattening protective film 8, the black mask 5 and the color filter 6, especially the surface tension, etc. It should be set optimally according to the
2b ≦ Cx <6b (b is the width of one pixel)
a ≦ Cy <3a (a is the length of one pixel and a <b)
It is preferable to set in the range.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible.
For example, in the above embodiment, the black mask 5 is also arranged in a lattice pattern between the pixels in the display region D1, but a black matrix is provided between the pixels only by overlapping adjacent color filter elements. The present invention is effectively applied to a color liquid crystal display element that is not present.

  Further, the present invention is not limited to the simple matrix type color liquid crystal display element, but can be applied to other various color liquid crystal display elements such as an active matrix type color liquid crystal display element.

DESCRIPTION OF SYMBOLS 1 Front glass substrate 2 Rear glass substrate 3 Scan electrode 4 Front orientation film 5 Black mask 6 Color filter 6R, 6G, 6B Color element piece 7 Dummy color filter 7R, 7G, 7B Dummy color element piece 8 Flattening protective film 9 Display electrode 11 Post-alignment film 111 Recess 12 Seal material 13 Gap material 14 Liquid crystal

Claims (3)

A first substrate disposed on the viewing side of the display and having a first electrode formed on the surface;
A second substrate disposed opposite to the electrode formation surface of the first substrate and having a second electrode formed on the opposite surface;
A liquid crystal layer sandwiched between opposing electrode forming surfaces of the first substrate and the second substrate;
A color filter disposed on either the first substrate or the second substrate so as to correspond to a plurality of pixels formed in a facing portion between the first electrode and the second electrode;
A light shielding film disposed at least in a peripheral portion surrounding a display region in which color filters are disposed corresponding to a plurality of pixels;
A dummy color filter disposed on the light-shielding film in the peripheral portion at a position separated from the boundary line between the display region and the peripheral portion by a predetermined distance and made of the same material as the color filter along the boundary line When,
A planarization protective film deposited to cover the light shielding film, the color filter, and the dummy color filter ;
Have
Each color element piece constituting the dummy color filter and the color filter is formed in the same rectangle,
The distance for separating the dummy color filter from the boundary line is twice the width of one pixel in the arrangement direction of the first electrode, and the length of one pixel in the arrangement direction of the second electrode. color liquid crystal display element characterized that you have been set respectively. The color liquid crystal display element according to claim 1, wherein the light shielding film is a resin black mask. 2. The light-shielding film is also disposed between pixels of a display area, and each color element piece of the color filter is filled and installed without protruding into a pixel space defined by the light-shielding film. Or the color liquid crystal display element of Claim 2 .