JPS6044778B2 - color cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve the image quality of a color cathode ray tube.

When an image is displayed on a cathode ray tube, the fineness of the image, that is, the resolution, is determined by the thickness of the electron beam that scans the phosphor surface of the cathode ray tube, the number of scanning lines, or spacing, and the number of picture elements on the phosphor surface.

The fluorescent surface of an incandescent cathode ray tube is coated with a phosphorescent material, so compared to the thickness of an electron beam, it can be said that there are an infinite number of picture elements. However, the fluorescent surface of a color cathode ray tube is divided into dots or stripes of the three colors red, blue, and green, so it cannot be said that there are an infinite number of picture elements. In other words, shadow masks or grills placed near the fluorescent surface for color selection are generally made by drilling large, square, or strip holes in the iron plate, but the processing method for these holes etc. Although it is difficult, the distance between the holes, that is, the distance between the picture elements on the fluorescent surface, is usually around 1 millimeter.

Also, the spacing between scanning lines varies depending on the screen size, but for example, if the screen height is 300 mm, then 0.
．． It will be about 6mm. Therefore, the fluorescent surface of a monochrome cathode ray tube should have better image quality than the fluorescent surface of a color cathode ray tube with a limited number of picture elements as described above.

However, when viewing television images, the criteria by which viewers judge the image quality is not directly tied to the resolution; images with a limited number of picture elements, such as those produced on color cathode ray tubes, are cleaner images. It may be determined that This is because if there is a part of the screen that does not emit light and there is a sharp border between it and the part that does emit light, this gives an accent to the image and gives a good impression to the viewer. The present invention focuses on the above points and provides means for improving the image quality of a color cathode ray tube.

Hereinafter, the present invention will be explained in more detail using the drawings. 1st
The figure shows a part of a fluorescent surface 1 coated in stripes, in which a green stripe 1, a red stripe 2 and a blue stripe 3 are arranged horizontally in order. . These stripes are usually continuous from the top to the bottom of the screen. The area where the green LED emits light is the area where the incident electron beam 7 is restricted by a mask or grill, and is surrounded by broken lines 11 and 12 in FIG. The same goes for the red phosphor stripe and the blue phosphor stripe. However, at the periphery of the portion hit by the electron beam, that is, near the broken lines 11 and 12 in FIG. 1, a sharp boundary cannot be seen due to scattering of the electron beam, and the brightness of the emitted light gradually decreases. Therefore, the screen is accent-free. However, the second
As shown in the figure, by providing the non-light emitting strips 13 on the fluorescent surface, the boundary between this portion and the light emitting portion can be sharpened, thereby accentuating the screen and improving the image quality as described above. Preferably, the strips 13 are not only non-luminescent, but also made of a light-absorbing material, such as graphite. To further illustrate an application example of the present invention, FIG. 3 shows a part of a conventional fluorescent surface called a black stripe, a green phosphor stripe, a red phosphor stripe 5, and a red phosphor stripe 5. Blue phosphor stripes 6 are arranged laterally in sequence, and black stripes 7 made of a light-absorbing material are embedded between these stripes.

In this case, the part of the electron beam incident on the stripe 4 of the green phosphor is the part surrounded by broken lines 41 and 42 in FIG. 3, which is wider than the width of the green phosphor. The same applies to the red phosphor stripe 5 and the blue phosphor stripe 6. In this case, the black stripe 7 gives an accent to the screen 4, resulting in a clearer image than in the case of the fluorescent surface shown in Fig. It is good to have 23 stripes that do not. Further, to show an example of the application of the present invention, FIG. 5 shows a part of a fluorescent surface of conventional 3, for example, called a hybrid type black stripe, with a stripe 8 of green phosphor and a stripe 8 of red phosphor. 9 and blue phosphor stripes 10 are arranged horizontally in order, and a black stripe 111 made of a light-absorbing material is embedded between these stripes.

In this case, the part of the electron beam impinging on the green phosphor stripe 8 is the slotted part 81, indicated by the dashed line in FIG. 5, which is limited by the slotted hole in the shadow mask. Therefore, the green phosphor stripe 8
The only part that emits light is the part where the green phosphor stripe 8 and the part 81 hit by the electron beam coexist. In this case as well, the black stripes 111 give an accent to the screen, but in order to further improve the image quality, it is effective to provide strips 121 that do not emit light, as shown in FIG. In this case, the spacing of the strips may be determined independently of the spacing of the slot-shaped portion 81 which is struck by the electron beam. According to the present invention, image quality can be improved, and the effect is great.

[Brief explanation of the drawing]

Figure 1 shows a part of a conventional striped luminescent surface, Figure 2 shows a part of a luminescent surface obtained by applying the present invention to the conventional striped luminescent surface shown in Figure 1, and Figure 3 shows a conventional black striped luminescent surface. Figure 4 shows a part of the fluorescent surface called the conventional black stripe in Figure 3, and Figure 5 shows a conventional hybrid type black stripe. FIG. 6 shows a part of a fluorescent surface called a black stripe, which is a part of a fluorescent surface obtained by applying the present invention to the conventional fluorescent surface called a hybrid type black stripe shown in FIG. 1 to 6, 8, 9, 10... phosphor stripes, 7,111... black stripes, 13
, 23, 121...Stripes that do not emit light.

Claims (1)

[Claims] 1. In a shadow mask type color cathode ray tube in which phosphor picture elements are arranged in a stripe pattern and a strip made of a non-luminous absorbing material is provided in a direction intersecting the stripes of the phosphor picture elements, A color cathode ray tube characterized in that the arrangement of strips made of a luminescent and absorbing material is different from the arrangement pitch of electron beam passing holes in a shadow mask.