JPS631407Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a shadow mask used in a color cathode ray tube.

FIG. 1 is a schematic cross-sectional view of a conventional color cathode ray tube. In this figure, 1 is a glass bulb consisting of a panel 2 and a funnel 3, and an electron gun 4 and a shadow mask 5 as a color selection mechanism are arranged in this glass bulb 1.

FIG. 2 is a partially enlarged schematic diagram of the shadow mask 5. As shown in FIG. In this figure, reference numeral 6 indicates an elongated slot formed in the shadow mask 5, and reference numeral 7 indicates a seam that separates the slots 6 in each row. Seam 7 is usually at right angles to the row of slots 6. Macroscopically, the seams 7 form rows 8, and the change in transmittance of the scanning lines (not shown) due to the seams 7 and interference with bright and dark stripes of the scanning lines cause a moiré pattern, which impairs image quality. It is well known that it has. When the seam 7 is perpendicular to the row of slots 6 as shown in FIG. One thing makes the moiré stronger. As a solution to this problem, a shadow mask 5 has been proposed, as shown in FIG. 4, which has a diagonal seam 11 that is perpendicular to the row of slots 6 and has an angle of +α. In this case, the change in transmittance of the scanning line pattern along the row of slots 6 approaches a flattening as shown by the characteristic () in FIG. 5 compared to that in FIG. 3, so the intensity of moiré is small. Become. However, since the shadow mask 5 shown in FIG. 4 has all the seams oriented in the same direction, it has the disadvantage that its mechanical strength is low and it cannot withstand molding.

This invention was made to eliminate the above-mentioned drawbacks, and provides a shadow mask with low moiré strength and high mechanical strength.

Hereinafter, embodiments of this invention will be described based on the drawings.

FIG. 6 shows an embodiment of this invention, in which the joints of the slots 6 have angles 11 of +α with the direction perpendicular to the rows of slots 6 and 12 of the slots 12 of −α, which are arranged repeatedly in each row. This is what has been done. With such a seam, the change in transmittance of the scanning line pattern along the rows of slots 6 is similar to that shown in FIG. Since +α and -α are repeated alternately, the mechanical strength is high, and the shadow mask 5 can sufficiently withstand molding.

As mentioned above, according to this invention, the intensity of moire can be reduced by alternately providing angles of +α and -α with respect to the direction perpendicular to the row of slots as the joints of the slots of the shadow mask. It is possible to obtain a shadow mask which is small in size and has a high mechanical strength, and which can sufficiently withstand molding processing.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of a conventional color cathode ray tube.
FIG. 2 is a partially enlarged view of a conventional shadow mask, FIG. 3 is an explanatory diagram of the shadow mask shown in FIG. 2, FIG. 4 is a partially enlarged view of another conventional shadow mask, and FIG.
This figure is an explanatory view of the shadow mask shown in FIG. 4, and FIG. 6 is a partially enlarged view of the shadow mask according to an embodiment of this invention. 5...Shadow mask, 6...Slot, 1
1, 12... Seam. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] In a shadow mask in which a plurality of elongated slots are bored and the slots in each row are separated by a thin seam, the seams have two types, one in which the angle between the two and the perpendicular direction to the row of slots is +α and -α. A shadow mask characterized by repeatedly arranging rows of.