JPH0453064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates specifically to color picture tubes of the type having a shadow mask mounted on a peripheral frame suspended in a relationship with a cathode ray luminescent screen. The present invention relates to a novel means for reducing microphonic vibrations of the shadow mask.

[Background of the invention]

In the above-mentioned color picture tube, the accuracy with which the electron beam emitted from the electron gun impacts each elemental area of the cathode ray-emitting screen is determined by the alignment of the apertures in the shadow mask and the elemental areas of the screen during operation of the tube. is largely determined by the accuracy of Although oscillations of the shadow mask relative to the bare areas of the screen are generally undesirable, when the oscillation frequency of the mask beats the electron beam scanning frequency, tube operation is severely disturbed.

The invention alters the resonant frequency of the mask to eliminate or significantly reduce the vibrational beat between the scanning frequency and the scanning frequency.

[Summary of the invention]

A color picture tube according to the invention is provided on two adjacent sides of the mask proximate each corner of the mask with tabs welded to the peripheral support frame and on both sides of said tabs between the mask and the peripheral support frame. This is improved by placing shims in contact with the mask and frame. This shim increases the resonant frequency of the mask.

[Description of recommended examples]

1 and 2 show a color picture tube having an evacuated glass envelope 20 having a substantially rectangular faceplate panel 22 and a tubular neck 24 connected thereto by a funnel 26. 18 is illustrated. A face plate panel has two axes that are orthogonal to each other: a long axis XX parallel to its wide direction (usually horizontal direction) and a short axis YY parallel to its narrow direction (usually vertical direction). I have it. These long and short axes are connected to the net 24
and the center of the panel 22. Panel 22 has a viewing faceplate 28 and a peripheral flange or sidewall 30 sealed to funnel 26 with frit material 27. A tricolor cathodoluminescent linear screen 32 is formed on the inner surface of faceplate 28. The screen 32 is comprised of an array of phosphor lines 32' extending generally parallel to the short axis Y--Y of the tube. A portion of the screen 32 is coated with a light absorbing material, as is well known in the art. The mask-frame structure 33 is made up of a substantially rectangular perforated color selection electrode, that is, a shadow mask 34, fixed to a peripheral frame 35 having an L-shaped cross section and a substantially rectangular shape. It is detachably attached to the inside of the panel 22 by a spring 42. The shadow mask 34 has a number of slit-shaped apertures arranged in generally parallel rows with the slits within each row separated by web portions. The frame 35 having the L-shaped cross section has two flanges 36 and 3.
There are 7. A first flange 36 faces toward the screen 32 and is generally parallel to the central longitudinal axis Z-Z, and a second flange 37 faces inwardly and approximately parallel to said central longitudinal axis Z-Z. extends vertically. The shadow mask 34 includes a peripheral skirt 41 that telescopes into a flange 36 of the frame.
is also formed.

Inside the net 24 is an inline electron gun 39.
(not shown schematically in the figure) generates three electron beams 38B, 38R and 38G and projects them along coplanar focused paths through shadow mask 34 and onto screen 32.

The tube 18 is connected to an external magnetic deflection yoke 40 surrounding the neck 24 and funnel 26 near their joint.
designed to be used with. When an appropriate voltage is applied to this yoke 40, three beams 3
8B, 38R and 38G scan the screen 32 so as to draw a rectangular raster thereon under the action of orthogonal magnetic fields.

FIGS. 3 and 4 show a mask-frame structure 33.
Details of the structure are shown. Shadow mask 3
4 has a central perforated portion 44 surrounded by a peripheral skirt 41. A plurality of tabs 46 integrally formed with the skirt 41 extend from the tip of the skirt 41. At least one of the tabs is provided at each corner of the shadow mask 34.
The tip of the tab 46 is fixed to the first flange 36 of the frame 35 by welding. The outer edge of the skirt 41 is smaller than the corresponding inner edge of the first flange 36, so that a gap 48 is formed between the skirt 41 and the flange 36. A plurality of wedge-shaped shims 50 are welded to the first flange 36 of the frame 35, the free ends of the shims 50 contacting the skirt 41 of the shadow mask 34. At the corners of the shadow mask 34, two shims 50 are provided on both sides of each tab 46.
In this embodiment, shim 50 is welded to frame 35.

Screen diagonal dimension is 68.58 cm (27 inches)
It was found that in the above-mentioned color picture tube that does not use shims, the mechanical resonance frequency of the shadow mask portion near the corners of the mask is approximately 115 Hz. Such a vibration frequency interferes with the electron beam deflection frequency and creates an unsightly beat image. When the mask moves on the Z axis, the mask skirt moves in the XY plane. Specifically, when the mask moves upward, the skirt moves inward. As shown in Figure 3, the resonant frequency of the mask can be adjusted by placing shims between the skirt and the frame with a spacing A (A = 38.1 mm or 1.5 inches in this example) on each side of each corner. rose to 145Hz. Due to this increase in the resonant frequency, the aforementioned unsightly beat image disappeared or was significantly reduced.

In the above explanation, one side of the shim is frame 3.
Although the shim 50 is welded to the first flange 36 of the shadow mask 35 and is disposed between the frame and the mask with the other surface in contact with the skirt 41 of the shadow mask 34, the shim 50 is formed integrally with the frame 35. may be done. Other types of shims that similarly increase the resonant frequency are also included in the spirit of the present invention. In one such variation, the shims described above may be replaced by bent-in tabs on the frame flange 36 that contact the mask skirt 41 at the same locations as the shims shown. . Another variation is to add outward flutes to the skirt 41 that contact the frame flange 36 at the same shim locations as shown.
It may be formed on top.

[Brief explanation of the drawing]

FIG. 1 is a simplified cross-sectional view taken along the longitudinal axis of the tube, showing the structure of one embodiment of the perforated mask type picture tube according to the present invention;
FIG. 2 is a rear view of the face plate and mask-frame structure of the picture tube shown in FIG. 1, FIG. 3 is a partially cutaway plan view of the corner portion of the mask-frame structure shown in FIG. 2, and FIG. 3 is a cross-sectional view taken along line 4--4 of a corner portion of the mask-frame structure of FIG. 3; FIG. 18...Color picture tube, 20...Envelope, 22
...Face plate panel, 36...
Flange, 46... tab, 50... shim.

Claims (1)

[Claims] 1. An exhaust having a substantially rectangular face plate panel having a major axis and a minor axis, and having a longitudinal center axis perpendicular to the major axis and minor axis and passing through the center of the face plate. the face plate panel has a generally rectangular shadow mask with at least one tab at each corner welded to a flange of the generally rectangular peripheral frame; extending substantially parallel to the central longitudinal axis; and further integrally formed with the peripheral frame on both sides of the tabs at each corner;
or at least two shims attached only to the peripheral frame, the shims contacting the shadow mask at a location away from where the at least one tab is welded between the shadow mask and the flange. , whereby the resonant frequency of the mask is increased.