JPS606067B2 - color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color picture tube with a slot-shaped shadow mask.

FIG. 1 shows a state in which an electron beam 1 lands on a crab light stripe 2 on the screen surface of a color picture tube equipped with a slot-shaped shadow mask.

In designing such a color picture tube, it is necessary to consider not only steady beam landing characteristics (color purity characteristics) but also temporarily changing beam landing characteristics. Beam landing characteristics that change temporarily include transient changes from turning on the television set to a steady state, changes in environmental temperature, and local thermal expansion of the shadow mask due to changes in the television signal (so-called local doming phenomenon), and among these, the probability of local doming occurring is extremely high. The area where the beam landing characteristics are particularly greatly affected by the local doming phenomenon is the area at a distance of 2'3 to 3'4 from the center of the screen surface in the X-X' direction (zone B), as shown by parallel hatching in Figure 2. It is.

Therefore, in this B zone, it is necessary to arrange the arrangement so that not only the steady color purity characteristics but also the color purity characteristics are not deteriorated by local doming. Generally, local doming causes a locally bright (white, shining) screen, so it is necessary to ensure that the color purity does not change in white.

The change in beam landing characteristics between steady state and local doming can be explained using Figure 3. The figure shows the relative positions of the screen panel, shadow mask, and beam. In steady state, shadow mask 3 It is relatively the same as panel 4 at a distance q. Then, during local doming, the shadow mask 3 moves to position 3' due to local thermal expansion of the shadow mask, and the distance between the screen panel and the shadow mask decreases from q to q'. Therefore, in a steady state, the projected spots on the screen panel surface of the center beam 5 and side beams 6 passing through one hole 7 with a shadow mask are:
However, during local doming, the mask hole 7 moves to position 7', so the projection spots of the center beam 5' and side beam 6' on the screen panel surface are at positions 8' and 9, respectively. It will move to position 9'. In other words, the deviation of the projection spot of the center beam on the screen panel surface caused by local doming, that is, the beam misregistration, is the distance Δ×, and the distance between the projection spots of the center beam and the side beams on the screen panel surface ( This means that the beam pitch) has decreased from P8 to PB. Taking the example of a 20-inch 110° deflection type color picture tube, the misregistration of the electron beam during local doming reaches as much as 130 degrees, and the beam pitch becomes smaller by several degrees.

Therefore, during local doming, the misregistration of the electron beam becomes extremely large, causing the scales of other colors to emit light. , beam pitch PB during local doming is regular pitch P
The problem is that the beam pitch PB in the steady state must be corrected in advance so that it is approximately equal to s (see FIG. 1). However, the amount of correction needs to be determined in consideration of both the steady state and local domin states. In the case of a 20-inch 110o deflection type picture tube, "B"
By increasing the beam pitch in the zone by about three degrees in a steady state, good color purity characteristics can be achieved both in a steady state and during local doming.

However, the beam pitch PB on the screen panel (crab light surface) is determined by the distance q value between the screen panel and the shadow mask, while the regular pitch Ps is generally determined by the pitch of the holes in the shadow mask. Therefore, in order to set the beam pitch to a certain desired value with respect to the regular pitch, the pitch of the holes in the shadow mask should be kept constant, and the curved surface shape of the shadow mask should be changed to an appropriate value. There are two design methods: one is to set the shadow mask to a specific value, and the other is to change the pitch of the holes in the shadow mask to an appropriate value. However, in general, if the curved shape of the shadow mask is locally changed to create a complicated shape, shape errors in manufacturing the shadow mask become large.
Further, it is not appropriate because it may cause large changes in shape during the picture tube manufacturing process. It is desirable to select a relatively simple curved surface for the shadow mask (such as a spherical surface or a rotating surface). In the present invention, the pitch of the holes in the shadow mask is changed as shown below so that the color purity characteristics in the steady state and the local doming state are maintained well without making the curved shape of the shadow mask a special shape.

Fig. 4 is a distribution diagram of the hole pitch (mask pitch) aH on the mask surface of the shadow mask of a conventional color picture tube, and Fig. 5 is a distribution diagram of the beam pitch PB on the screen panel surface in a steady state. The light stripe pitch PH also shows the distribution of the regular bush pitch Ps.

FIG. 6 shows the distribution of the mask pitch aH on the mask surface in the color picture tube of the present invention, and FIG. 7 shows the beam pitch PB and crab light distribution in a steady state on the screen panel surface of the color picture tube of the present invention. Body stripe pitch PH
"Distribution of support pitch Ps is shown. In both cases, the distance from the shadow mask and the center of the screen panel surface (r
The changes in each pitch with respect to m and r) are shown for each of the X, Y, and PQ axes. Taking the case of a 20-inch 110o deflection type color picture tube as an example, when using the subordinate mask shown in Fig. 4, the mask pitch aH: 0.730 and PB, PH, Ps in Fig. 5 = 0.260. It is almost constant throughout the shadow mask and screen panel surface, and there is no problem in color purity characteristics under normal conditions.

However, when local doming occurs, color purity characteristics tend to deteriorate particularly in the B zone. However, in the color picture tube of the present invention shown in FIG. 6, the mask pitch aH is expressed by the following equation. aH=a.

(1jupi, Shibaju is 2) (1ju8, 〆+8 or 4) ao:
Mask pitch at the mask center x: Distance y from the mask center vertical axis; Distance from the mask center horizontal axis where , , 82 is a negative constant, Q2, 8 . is a positive constant.

And B zone (x=(2'3~3'4)xmax)
The horizontal array pitch aH at is smaller than the horizontal array pitch ao at the center, as shown by the curve x.

For a 20-inch 1100 polarization color picture tube, ao = 0.730 Q, = -1.2587 x 10-6 Q2 = 2.7956 x 10-11 81:8.3187 x 10-7 82 = -3.6181 xio-11 Since the curved shape and q value of the shadow mask are the same as those of the conventional one, the support pitch Ps in the B zone on the screen panel surface is about 3 times smaller than the beam pitch PB.

By doing so, it is possible to improve the color purity characteristics during local doming while maintaining the color purity characteristics in the steady state. In addition, the conventional mask pitch (uniform over the entire mask surface)
In the region where the pitch is finer than that, the width of the horizontal hole W of the slot hole of the shadow mask and the corresponding base light stripe width on the screen panel surface is made smaller. By increasing the number of days, the mask TM (beam utilization factor),
The halo stripe TM (light emitting area) and guard band (margin against mislanding of the beam) can be almost the same as conventional color picture tubes, and the pitch unevenness rate is 4. It is not at all noticeable to the eye.

By changing the mask pitch from the center to the periphery in this way, the color during local doming can be improved while maintaining the color purity characteristics in the steady state without changing the curved surface of the conventional relatively simple shadow mask. Purity characteristics can be improved. -

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the screen surface of a color picture tube, Fig. 2 is an explanatory diagram of the B zone of the screen surface, Fig. 3 is an explanatory diagram of changes in the beam landing state during local doming, and Fig. 4 is an explanatory diagram of the change in the beam landing state during local doming.
The figure is a mask pitch distribution diagram of a conventional shadow mask.
The figure is a distribution diagram of beam pitch, crab photon stripe pitch, and support pitch on the screen surface of a color picture tube using a conventional mask, and FIG. 6 is a mask pitch distribution diagram of a shadow mask of a color picture tube according to the present invention. FIG. 7 is a distribution diagram of the beam pitch, the crab light stripe pitch, and the regular bush pitch on the surface of the color picture tube of the present invention. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 The horizontal arrangement pitch of each slot hole in the center and periphery of the mask surface is a_O and a_H, respectively, and the distance from the central vertical axis of the mask surface is x (the maximum is x
max), and the distance from the central horizontal axis of the mask surface is y, then a_H=a_O(1+α_1x^2+α_
2x^4) (1+β_1y^2+β_2y^4) However, α_1, β_2 are negative constants, α_2, β_1 are positive constants.
/4) A color picture tube comprising a shadow mask in which the horizontal alignment pitch a_H at xmax) is smaller than the horizontal alignment pitch a_O at the center.