JPS631406Y2 - - 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, reference numeral 1 denotes a glass bulb consisting of a panel 2 and a funnel 3. Inside this glass bulb 1, an electron gun 4 and a shadow mask 5 as a color selection mechanism are arranged.

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 thin seam separating the slots 6 in each row. Seam 7 is usually at right angles to the row of slots 6. The seams 7 macroscopically form rows 8, and the change in transmittance of the scanning line (not shown) due to the seam 7 and interference with the bright and dark stripes of the scanning line 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 that has a diagonal seam 11 that is perpendicular to the row of slots 6 and has an angle of +α, as shown in FIG. In this case, the change in transmittance of the scanning line pattern along the row of slots 6, as shown by the characteristic () in FIG. 5, approaches a flattening compared to that in FIG. 3, so the intensity of moiré is becomes small.
However, since the shadow mask 5 shown in FIG. 4 has all seams oriented in the same direction, it has a drawback that it has low mechanical strength and 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 and angles of −α with the direction perpendicular to the rows of slots 6. They are arranged above and below. With such a seam, the change in transmittance of the scanning line pattern along the row of slots 6 will be the same as the fifth one.
It is equivalent to that shown in the figure, so the moiré strength is small, and since the direction of the seam is alternately +α and -α above and below the slot 6, the mechanical strength is high, so The shadow mask 5 has sufficient resistance to 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 the drawing]

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 having two slots arranged above and below one slot.