MXPA98005420A - Pixel for screen and method for form - Google Patents

Abstract

A pixel for a display device or screen having a shape delineated by a black matrix or a barrier. The pixel is shaped like a polygon that has 2 (n + 1) angled portions where n is a natural number equal to or greater than 2. Such a pixel can also be produced without a previously formed black matrix

Description

PIXEL FOR SCREEN AND METHOD FOR FORMING IT DESCRIPTION OF THE INVENTION This application claims the priority of patent applications nos. 97-30689, filed on July 2, 1997, 97-40175 filed on August 22, 1997, and 97-48484 filed on August 30, 1997, and 98-19409 filed on May 28, 1998, to whose content it is referenced here. The present invention relates to a pixel for a screen and a method for forming it, and more particularly to a method for forming a pixel that serves to produce a visual image on the screen with better visibility. The present display screens or devices, include liquid crystal devices (LCD), panels for plasma screens (PDP), fluorescent vacuum screens (VFD), and cathode ray tubes (CTR).

These display devices are used in TV, monitors, calibration and informational boards. That type of display devices has a plurality of pixels which are the basic units for forming a screen. The combinations of the pixels produce the desired character or images on the screen. For example, the CRT has a plurality of pixel triodes formed by phosphors of colors red (R), green (V) and blue (B), and the PDP has pixels formed by crossed electrode crossing points through a matrix. Such a pixel has an optional model feature of each type of screen. This model can be delineated by means of a previously processed black matrix or barrier. In the CRT, the pixel has a point or groove shape delineated by a black matrix that is previously formed on the inner surface of the panel. On the LCD, the pixel has a grid or rectangular shape delineated by a black matrix placed on a color filter. In the PDP or any other flat panel display, the pixel can be formed rectangularly delineated by means of a barrier placed between the substrates. However, that type of pixel has a limit in which the use in the presentation of digitalized character information for use in multimedia can not be adapted correctly. The digitized character, composed of combinations of rectilinear portions and curved portions, is shown on the screen completely with straight lines. Therefore, the visibility of the character shown on the screen depends on how many rectilinear portions are in the pixel. From this point of view, the aforementioned pixels can present good visibility with respect to the vertical and horizontal portions of the character because they retain many of the straight lines in those directions. However, with respect to the inclined portions of the character, those pixels reveal limited visibility due to the absence of straight lines in that direction. Whereas 50% or more portions of the character are presented on the screen in the inclined direction. It can be easily known that conventional pixels would not be applied directly to conventional multimedia presentation devices. It is an object of the present invention to provide a method for forming a pixel for a screen that serves to produce a visual image on the screen with better visibility. In order to achieve those objects and others, the present invention provides a pixel for a screen having a shape delineated by means of a black matrix or a barrier. The shape of the pixel is formed with a polygon having 2 (n + l = angled portions where n is a natural number equal to or greater than 2. The display device includes a panel and a phosphor screen formed on an inner surface of the panel and having a plurality of pixels each of the pixels is shaped as a polygon having 2 (n-f1) angled portions where n is a natural number equal or greater than 2. A shadow mask is mounted within the panel and has a plurality of apertures corresponding to the pixels. Each of the openings is formed as a polygon that has 2 (n + l) angled portions where n is a natural number equal to or greater than 2. In the pixel formation method, a photosensitive layer is first formed on the inner surface of the panel. Then a mask is mounted inside the panel. The shadow mask has a plurality of openings shaped like a polygon having 2 (n + 1) angled portions where n is a natural number equal to or greater than 2. The photosensitive layer is then exposed to light by placing the central axis of the light source to be placed on the baseline that passes through the opposite angled points of the aperture and vibrate the light source in the horizontal and vertical directions. Then the stage of formation of the photosensitive layer, the stage of mounting the shadow mask and the stage of exposure to light are repeated with respect to the inner surface of the panel with the photosensitive layer exposed to light, a number of times equal to the number of lines passing through the residual angled points of the opening. After the repeated process steps, a graphite layer is formed on the inner surface of the panel with the photosensitive layer. The graphite layer is then recorded and developed to form a matrix black on the inside surface of the panel. Then, a phosphor layer is formed on the inner surface of the panel with the black matrix. The phosphor layer is then exposed to light and developed to form a phosphor screen on the inner surface of the panel. The resulting phosphor screen has a plurality of pixels formed as a polygon having 2 (n + l) angled portions where n is a natural number equal to or greater than 2. Such a pixel can be processed without the previously formed black matrix. A more complete appreciation of the invention and many of its advantages will be apparent as it is better understood by reference to the following detailed description considered in conjunction with the accompanying drawings, in which: Figure 1 is a schematic sectional view of a CRT according to a preferred embodiment of the present invention; Figures 2A to 2D are views illustrating the processing steps of the shadow mask shown in Figure 1; Figure 3 is a plan view showing a work model plate used in the envelope mask processing steps; Figure 4 is a schematic sectional view of a device for exposure to light to form a pixel with the shadow mask; Figure 5 is a flow diagram illustrating the steps of processing a black matrix with the light exposure device shown in Figure 4; Fig. 6 is a view showing the lines crossing the opposite angled points of a beam guide aperture of the shadow mask; Figures 7A to 7C are views illustrating the stages of exposure to light in Figure 5; Figures 8A and 8B are views showing the position of the light source of the light exposure device in the second and third stages of exposure to light; Figure 9 is an exemplary view showing character information formed with combinations of pixels shown in Figure 1; Figure 10 is a schematic sectional view of a screen according to a second preferred embodiment of the present invention; and FIG. 11 is a cross-sectional view of a screen according to a third preferred embodiment of the present invention. Now, the preferred modalities of the present invention with reference to a CRT. Figure 1 is a schematic sectional view of a CRT according to a preferred embodiment of the present invention. As shown in Figure 1, the CRT includes a faceplate panel 2 having an internal phosphor screen 4, and a shadow mark 10 placed directly below the phosphor screen 4. For simplification purposes, they will be omitted the explanations regarding the other elements of the CRT. The phosphor screen 4 is formed with a plurality of triodes of red (R), green (G) and blue pixels (B) 8. Correspondingly, the shadow marker 10 has a plurality of beam guide apertures 10a pointing to the pixels 8. The pixel 8 is shaped as a polygon having 2 (n + 1) angled portions where n is a natural number equal to or greater than 2. In this preferred embodiment, a method for forming a hexagonal shaped pixel will be exemplified. In order to form the pixel 8, the shadow mask 10 must be processed first in the following manner. Figures 2A to 2D illustrate the processing steps of the shadow mask 10. As shown in Figure 2A, the photosensitive layers 12 and 14 are formed first by applying a photosensitive solution on both sides of the lens. a metal plate 10"Then, as shown in Fig. 2B, the working model plates 16 and 18 are placed in the photosensitive layers 12 and 14, respectively Fig. 3 specifically shows a work model plate 16 or 18. The first work pattern plate 16 is formed with graphitized hexagonal shaped portions 16a and transparent portions 16b.The second work pattern plate 18 has the same structure as the first work model 16 glass plate. , the sizes of the graphitized hexagonal shaped portions 18a and the transparent portions 18b of the second work plate 18 differ from those of the graphitized portions 16a and the transparent portions 16b of the first work pattern plate 16. After work model plates 16 and 18 are placed in their proper places, a light source 20, such as a mercury lamp is placed adjacent to each of the work pattern plates 16 and 18, and irradiates light. At this time, the photosensitive layers 10 and 12 are exposed to the light transmitted through the transparent portions 16b and 18b, and subsequently revealed with a cleaning solution. As a result, as shown in Figure 2C, only the portions exposed to light 12a and 14a are left on the sides of the metal plate 10 '.

At this time, as shown in Figure 2SD, when the sides of the plate 10 'are etched with an etching solution, the unexposed portions of the plate 10 * are etched to form the hexagonal shaped beam guide openings. to. Then, the portions exposed to light 12a and 14a are removed from plate 10 *. Finally, the plate 10 'with the beam guiding openings 10a are processed through a subsequent forming process to form a complete shadow mask 10. Figure 4 is a light exposure device for forming pixels 8 of the screen of phosphorus 4 with the leftover mask 10 described above. As shown in Figure 4, the light exposure device includes a main body 20, and a light source 32, a shutter 34, a correction lens 36 and a filter 38 sequentially positioned in the main body 30. In the pixel formation process, a black matrix is first formed on the inner surface of the panel 2. FIG. 5 illustrates such a black matrix formation process. For the first time, a first photosensitive layer is formed on the inner surface of the panel 2. A first stage of exposure to light is then performed by mounting a shade mask 10 with the hexagonal shaped beam guide openings 10a on the side of the upper opening of the main body 20 of the exposure device.

In the first stage of exposure to light, the central axis of the light source 32 is positioned on a first line Al, shown in figure 6, between the lines crossing the opposite angled points of the beam guide aperture 10a . At this time, the light source 32 radiates light in selected portions of the first photosensitive layer through the beam guide aperture 10a while vibrating in the horizontal and vertical directions. Subsequently, a first stage of development and drying is performed with respect to the portions exposed to the light of the first photosensitive layer. As a result, as shown in Figure 7A, a rectangular-shaped layer 51 is formed. With the removal of the shadow mask 10, a second photosensitive layer is formed on the inner surface of the panel 2 while the photosensitive layer is covered. of rectangular shape 51. Then the shadow mask 10 is again provided in its proper place and a second stage of exposure to light is made with respect to the second photosensitive layer while changing the position of the light source 32. For this purpose as shown in the figure 8A; the light source 32 is rotated 60 degrees from the position in the first stage of light exposure in the direction in 1 clockwise and is placed in a second line A2 passing through other opposite angled points of the beam guide aperture 10a. Then the light source 32 radiates light at the selected positions of the second photosensitive layer through the beam guide aperture 10a while vibrating in the horizontal and vertical directions. Subsequently, a second development and drying step is performed with respect to the portions exposed to the light of the second photosensitive layer. As a result, as shown in Figure 7B, a diamond-shaped photosensitive layer 52 is produced. Likewise, a third stage of photosensitive layer formation, a third stage of exposure to light and a third stage of developing and drying is perform on the inner surface of the panel 2. On the. third stage of exposure to light, as shown in Figure 8B, the light source 32 is rotated from the second line A2 by 120 degrees in the counterclockwise direction, and thus the center axis is placed on a third line A3 that still traverses other opposing angled points of the beam guide aperture 10a. As a result, as shown in Figure 7C, a hexagonal shaped photosensitive layer 53 is produced. This hexagonal portion is where the matches will be placed later.

After the photosensitive layer in hexagonal form 53 is obtained, graphite which is a black matrix forming material, coats the inner surface of the panel 2 while covering the photosensitive layer of hexagonal shape 53., When an etching step, and a fourth stage of developing and drying is performed, the photosensitive layer 53 is removed from the interior surface of the panel 2 to obtain a black matrix 6. At this time, the portion from which the photosensitive layer 52 was removed, is left with an empty space. These hexagonal shaped pixels 8 have good presentation characteristics as described below. Figure 9 exemplifies the case in which the character "A" is displayed on the screen with combinations of the hexagonal shaped pixels 8. In contrast to the character information formed by means of combinations of the pixels in the form of points or rectangles , such character information 54 shows improved visibility in the inclined direction. In this regard, considering that 50% or more of the portions of the character information are displayed in the inclined direction of 30 to 670 degrees it is easily known that the hexagonal shaped pixels 8 can serve to produce screen images with relatively high visibility best. In addition, it was demonstrated by means of experiments repeated that the hexagonal-shaped pixels 8 serve to improve the visibility of the English, Korean or Chinese characters shown on the screen. A second embodiment of the present invention will also be explained with reference to a CRT. Figure 10 shows a CRT according to the second preferred embodiment of the present invention. As shown in Figure 10, the CRT includes a faceplate panel 60 having an internal match screen 62, and a shadow mask 66 placed behind the match screen 62. As in the first preferred embodiment, the screen phosphor 652 is formed with a plurality of hexagonal shaped pixels 64. However, in this preferred embodiment, the pixels 64 are processed without a previously formed black matrix. The pixels corresponding to the colors R, G and B are successively formed on the inner surface of the panel 60. It is clear that the shadow mask 66 with a plurality of hexagonal beam guide openings is still required in the forming process of pixel. The processing steps of the shadow mask are the same as those of the first preferred embodiment. In the pixel formation process, except for the light exposure stage, other processing steps they are done in the usual way. As in the first preferred embodiment, the stage of exposure to light is performed by placing the central axis of the light source in each of the lines crossing the points of opposite interior angles of the pixel 64 and vibrating the light source in the horizontal and vertical directions in each place. In this way, the resulting pixel 64 can be formed with a hexagonal shape. Therefore, as described above, the character information displayed on the screens with combinations of the hexagonal shaped pixels exhibits improved visibility characteristics. A third embodiment of the present invention will be explained with reference to a CRT. Figure 11 shows a CRT according to the third preferred embodiment of the present invention. As shown in Figure 11, the CRT includes a faceplate panel 70 having an indoor phosphor screen 72 and a shadow mask 76 positioned behind the phosphor screen 72. In the preferred embodiment, each of the pixels 74 of a match screen 72 is formed with a slot form. In contrast, as in the above embodiments, each of the beam guide openings 76a of the shadow mask 76 is formed with a hexagonal shape.

The size of the beam guide aperture 76a is set to be smaller than that of the pixel 74. In this way the electron beam passing through the beam guide aperture 76a can land on the phosphor screen 72 with a hexagonal shape. . This creates the same effect as with the pixels d * hexagonal shape according to the above modalities. In the preferred embodiments mentioned above, it was explained that the development stage will be repeated after each stage of exposure to light. However, it is also possible to carry out the development step only once after all the stages of exposure to light have been completed. However, it is also possible to carry out the development step only once after all the stages of exposure to light have been carried out. In the stage of exposure to light, the light source 32 vibrates in the horizontal and vertical directions preferably with amplitudes in the range of 0.2mm and 0.3mm, respectively. It is also preferable that as the exposure to light operation is repeated with the light source in different positions, the time of exposure to light is gradually reduced in view of the degree of exposure to light in each position. As described above, the hexagonal shaped pixels according to the present invention can serve to give relatively better visibility of the displayed screen images and thus can be applied for multimedia use. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will appreciate that various modifications and substitutions may be made without departing from the spirit and scope of the present invention as described in the appended claims.

Claims (12)

1. CLAIMS 1.- A presentation device having a phosphor screen, comprising: a plurality of pixels formed in the phosphor screen, each of the pixels having a shape delineated by a black matrix or a barrier, in which the The shape of the pixel is formed as a polygon that has 2 (n + l) angled portions where n is a natural number equal to or greater than 2.
2. 2. The presentation device according to claim 1 wherein the device presentation is a cathode ray tube.
3. 3. A screen device consisting of: a panel a phosphor screen formed on an interior surface of the panel and having a plurality of pixels, each of the pixels is formed with a polygon having 2 { n + l) Angled portions where n is a natural number equal to or greater than 2, and a shadow mask mounted within the panel and having a plurality of apertures corresponding to the pixels, each of the openings is formed as a polygon that has 2 (n + l) angled portions where n is a natural number equal or greater than 2.
4. 4.- A screen device, consisting of: a panel; a phosphor screen formed on an inner surface of the panel and having a plurality of pixels, each of the pixels is formed with a predetermined shape, and a shadow mask mounted within the panel and having a plurality of openings corresponding to the pixels, each of the openings are formed as a polygon that has 2 (n + l) angled portions where n is a natural number equal to or greater than 2 and that have a size less than the size of the pixel.
5. 5. A method for forming a pixel for a screen device having a panel with an interior surface, the method comprising the steps of: forming a photosensitive layer on the interior surface of the panel, mounting a shadow mask within the panel. , the shadow mask has a plurality of openings formed as a polygon having 2 (n + l) angled portions where n is a natural number equal to or greater than 2; exposing the photosensitive layer to the light by placing the central axis of a light source to be placed on a baseline that traverses the angled points of the aperture and vibrating the light source in the horizontal and vertical directions; repeating the photosensitive formation step, the step of assembling the shadow mask and the stage of exposure to light with respect to the inner surface of the panel with the photosensitive layer exposed to light as many times as the number of lines passing through them. residual angulated points of the aperture form a layer of graphite on the inner surface of the panel with the photosensitive layer; engrave and reveal the graphite layer to form a black matrix on the inner surface of the panel; forming a phosphor layer on the inner surface of the panel with the black matrix; expose the phosphor layer to light; and revealing the phosphor layer to form a plurality of pixels on the inner surface of the panel.
6. 6. - The method according to claim 5 wherein the step of exposure to repeated light is performed by rotating the light source by means of a predetermined degree alternately in a clockwise direction and in wasting counterclockwise from the baseline that crosses the opposite angled points of the opening.
7. 7. - The method according to claim 6 in which the light source is rotated by 60 °.
8. 8. - The method according to claim 5 in the which the time of exposure to light to form the black matrix is gradually reduced in the repeated stage of exposure to light.
9. 9. A method for forming a pixel pair even a display device or screen having a panel with an interior surface, comprising the steps of: forming a photosensitive layer on the interior surface of the panel, mounting a shadow mask within the panel , the shadow mask has a plurality of openings formed as a polygon having 2 (n + l) angled portions where n is a natural number equal to or greater than 2; exposing the photosensitive layer to the light by placing the central axis of a light source to be placed on a baseline that traverses the angled points of the aperture and vibrating the light source in the horizontal and vertical directions; revealing the phosphor layer exposed to light to form a plurality of pixels on the inner surface of the panel; and repeating the phosphor layer formation step, the shadow mask assembly step, the light exposure step and the developing step with respect to the inner surface of the panel with the phosphor layer revealed.
10. 10. - The method according to claim 8, wherein the step of exposure to repeated light is performed by rotating the light source by means of a predetermined degree alternately in a clockwise direction and in wasting counterclockwise from the baseline by crossing the opposite angled points of the opening.
11. 11. The method according to claim 10, wherein the light source is rotated by 60 °.
12. 12. - The method according to claim 8 in which the time of exposure to light is gradually reduced in the repeated stage of exposure to light.