JPH0373981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cathode ray tube, and particularly to the outer shape of the panel.

[Technical background and problems of the invention]

In general, a cathode ray tube has an envelope that is substantially rectangular in shape and includes a panel having a phosphor screen on the inner surface, a funnel extending to the panel, and a neck containing an electron gun. In such a cathode ray tube, the outer surface of the panel is curved to bulge outward in order to equalize the distances from the center of deflection of the electron beam from the electron gun to each part of the screen scanning surface as much as possible. When designing the outer surface shape of this panel, a symmetrical design along the vertical, horizontal, and diagonal axes is generally used to facilitate the design and to accommodate the thickness of the panel glass. A panel outer surface shape that exhibits a cylindrical surface that is flat only in the vertical axis direction has also been proposed. In a cathode ray tube having such a panel, for example, in a large tube of 20 inches or more, _as shown in FIG. If the side wall height is higher than _h2 , there is a problem in that implosion is extremely likely to occur due to the pressure difference between the inside and outside of the tube during evacuation. In other words, when the pipe becomes large, the metal band that is wrapped around and tightened around the side wall of the panel to prevent implosion cannot sufficiently evenly apply the compressive force at the side part compared to the diagonal part. There is a problem in that deformation strain due to external pressure on the long sides cannot be sufficiently removed.

[Purpose of the invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a cathode ray tube having a panel that reduces distortion due to external pressure on the long sides and has excellent explosion-proof performance.

[Summary of the invention]

The present invention defines the radius of curvature R _V in a plane including the vertical axis which is the short axis of the outer surface of a curved panel, the radius R H of curvature in the plane including the horizontal axis which is also the long axis, and the radius of curvature R _H in the plane including the horizontal axis which is also the long axis. R _V <R _H between the radius of curvature R _D on the containing surface,
In addition, by setting R _V <R _D and making the radius of curvature of the outer surface of the panel smaller on the short axis side, the height of the panel side wall can be balanced between the long axis side and the short axis side, and the overall explosion-proof performance can be improved. Furthermore, the radius of curvature R(θ) of the panel outer surface of the line along the angle (θ) from the panel center to the vertical axis is expressed as R(θ)=R ₀ +
By setting R ₁ cos2θ+R ₂ cos4θ (where R ₀ , R ₁ and R ₂ are constants), the radius of curvature of the panels can be smoothly connected.

[Embodiments of the invention]

Examples of the present invention will be described below. Second
The figures are an external view and a cross-sectional view of each axis of a panel showing an embodiment of the present invention. In Figures 2 and 3,
The panel 21 is composed of a curved effective section 22 and substantially rectangular side wall sections 23 and 24. Since a phosphor screen (not shown) is formed on the inner surface of the panel glass effective portion 22, its surface precision is maintained at a sufficiently high level, and glass defects such as bubbles and scratches can be detected with sufficient precision as a whole of the panel glass. managed. When the inside is vacuum-sealed, stress applied by external pressure is applied inward to the effective portion 22 and the funnel portion (not shown), and to the side wall 2.
3 and 24 to the boundary of the effective section, the stress is balanced by tightening the side walls 23 and 24 with metal bands (not shown). At this time, in order to balance the tensile stress caused by the metal band as a whole, it is necessary that the entire surface of the side walls 23 and 24 be tightened evenly. From this point of view, the side wall heights H _V , H _H and _HD on the vertical, horizontal and diagonal axes are important factors, and by making the side wall heights on each axis approximately equal, each side wall, especially on the long side, It is possible to alleviate stress and strain. Therefore, in order to make the side wall heights H _V , H _H and _HD in each axis almost equal, that is, H _V = H _H = H _D (1), the outer surface curvature of the panel effective portion 22 in each axis must be The radius must satisfy R _V <R _H <R _D (2). Here, R _V is the radius of curvature in the plane containing the vertical axis, which is the minor axis, R _H is the radius of curvature, in the plane including the horizontal axis, which is the major axis, and R _D is the radius of curvature, in the plane including the diagonal axis. be. Also, in large pipes (1)
Even if the formula is not completely satisfied, H _V ≧H _H ≧H _D ……(3) In other words, it is sufficient to approximately satisfy the formula (3), and in this case, practically, R _V < As long as R _H and R _V <R _D (4), a sufficient effect can be obtained even if R _H R _D is satisfied. In other words, in a cathode ray tube that has a panel with the radius of curvature of the outer surface in each axis as shown in equation (4), it is possible to significantly reduce residual stress strain especially on the long side walls and balance the entire side wall, which makes it possible to achieve better balance than before. agreement
1.5 to 2 times more explosion-proof strength can be obtained.
In order to connect the radii of curvature of curved panels that have different radii of curvature along each axis as smoothly as possible, the curvature of the angle (θ) from the center of the panel to the vertical axis (V) is determined as shown in Figure 4. Radius R
(θ) can be arbitrarily designed by selecting constants R ₀ , R ₁ and R ₂ according to R(θ)=R ₀ +R ₁ cos2θ+R ₂ cos4θ (5).

Alternatively, as shown in Figure 4, the radius of curvature R(x) in the direction parallel to the vertical axis (V) at a point x away from the center of the panel on the horizontal axis (H) is R(X) = R _V −R _H −√( _H ) ² −() ² ) ...(6) You may also connect them as follows.

In the above explanation, all curvature radii are expressed as a single curvature radius, but in the present invention, one curvature radius, for example R _V , has a radius of curvature that gradually changes from the center to the periphery of the panel face. It goes without saying that this also includes the case of so-called compound radius of curvature. In such a case, for example, the value of the approximate average radius of curvature when the composite radius of curvature is approximately expanded into a series may be used as one radius of curvature in the present invention.

〔Effect of the invention〕

As described above, according to the present invention, a balanced stress is applied by the metal band wrapped and tightened around the side wall of the panel, and the conventional residual tensile stress on the long side wall is reduced and alleviated, so that the explosion-proof strength can be improved, and especially Suitable for large pipes. Furthermore, since the maximum heights of the outer peripheries of the panels are approximately the same height and are on the same plane, the entire screen feels more flat, making it possible to create a panel that is visually very easy to see.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a conventional panel, Fig. 2 is a schematic diagram of a panel for explaining an embodiment of the present invention, Fig. 3 is a sectional view of Fig. 2, and Fig. 4 is an implementation of the present invention. FIG. 3 is a schematic plan view of a panel for explaining an example. 21... Panel, 22... Effective portion, 23... Long side side wall, 24... Short side side wall.

Claims (1)

[Claims] 1. A cathode ray tube having a curved panel having a substantially rectangular shape and having a phosphor screen on the inner surface,
a radius of curvature R _V of the outer surface of the panel in a plane including the vertical axis that is the short axis of the curved panel; a radius of curvature R _H of the outer surface of the panel in a plane including the horizontal axis that is the long axis of the curved panel; The radius of curvature R of the outer surface of the panel in a plane including the diagonal axis of the curved panel has the relationship R _V < R _H and R _{V < R D ,} and the distance from the center of the panel to the vertical axis Angle (θ)
The radius of curvature R (θ) of the outer surface of the panel along the line along the line is obtained by R (θ) = R ₀ + R ₁ cos2θ + R ₂ cos4θ (where R ₀ , R ₁ and R ₂ are constants). cathode ray tube. 2 The radius of curvature R(X) of the outer surface of the panel in the direction parallel to the vertical axis at a position x apart from the center of the panel on the horizontal axis is R(X)=R _V −(R _H −√( _H ) ² -() ² ) The cathode ray tube according to claim 1, characterized in that it is obtained by the following method. 3. A claim characterized in that, when the side wall heights on the vertical axis, the horizontal axis, and the diagonal axis are H _V , H _H , and HD _D , respectively, H _V = H _H = _HD . The cathode ray tube according to item 1.