JPS6116450A - Flat type cathode-ray tube - Google Patents

Abstract

PURPOSE:To correct so-called deflecting distortions such as pincushion distortions by providing a fluorescent screen with a curved surface which is undulated in a direction of incidence of an electron beam corresponding to deflecting distortions. CONSTITUTION:A flat type cathode-ray tube comprises a flat glass tube body 5 which is consisted of a flat front panel 1, a screen panel 2, a funnel 3 and a neck 4, and a fluorescent screen 6 is provided in the inner surface of the screen panel 2, which is positioned downward in respect to the axis 9 of its electron gun 7, and the electron beam 8 from the electron gun 7 is scanned on the fluorescent screen 6 in a horizontal and a vertical directions by an electromagnetic deflecting means. In this case, the electromagnetic deflecting means is composed of a deflecting yoke with a uniform magnetic field. The thickness of the screen panel 2 correspond to the lower end of the side close to the electron gun in the fluorescent screen 6 is thickened so as to inwardly raise the central portion which is thicker than both ends in correspondence with curves of pincushion distortions and so as to reduce the volume of the raised portion in accordance with the upper end of the fluorescent screen, and the fluorescent screen 6 is adhered and formed in the inner surface of the screen panel 2 having the curved surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to flat cathode ray tubes, and more particularly to correction of screen deflection distortion such as threading distortion.

BACKGROUND ART AND PROBLEMS The present applicant has developed flat cathode ray tubes having the configurations shown in FIGS. 1 to 3, for example. This flat cathode ray tube has a flat front panel + 1
) and a curved screen panel facing it (2)
A flat glass tube body 5) consisting of a funnel (3) and a neck (4) is provided, a fluorescent surface (6) is formed on the inner surface of the screen panel (2), and a fluorescent surface (6) is formed in the neck (4). An electron gun (7) is arranged, and the electron beam (8) from the electron gun (7) is caused to fluoresce by an electromagnetic deflection means (not transmitted orally).
hi (61) is configured to scan the fluorescent surface (6) horizontally and vertically. In this case, the fluorescent surface (6) is deviated from the axis (9) of the electron gun (7). placed in the correct position.

This is to protect the fluorescent surface (6) from deterioration in brightness due to collisions of ionized gas molecules. This flat cathode ray tube (
11, as shown in FIG.
6) enters at a large angle of incidence θ. In such flat cathode ray tubes, due to the difference in the reach distance of the electron beam between the center and the periphery of the screen, the distance from the electron gun axis (9) is particularly large, and the deflection angle is large at the bottom of the screen (where the electron gun (See Figure 1).

As iE methods for compensating for threading distortion, there are (i) a correction method using a deflection current, and (ii) a correction method using a non-uniform magnetic field deflection yoke. Conventionally, one or both of these methods have been used to correct threading distortion. was being done.

However, if we take the flat cathode ray tube mentioned above as an example, the former correction method consumes too much power and the cost of circuit components is too high, and the latter correction method requires
A flat tube with a 70° deflection had the disadvantage that the beam spot size at the left and right corners of the upper end of the white surface near the electron gun deteriorated by about 10% in the vertical direction due to deflection distortion.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a flat cathode ray tube which eliminates the above-mentioned drawbacks and can correct so-called deflection distortion such as threading distortion by the curved shape of the phosphor surface without relying on a circuit.

SUMMARY OF THE INVENTION The present invention is a flat cathode ray tube that has a curved fluorescent surface that undulates in the direction of electron beam incidence in response to deflection distortion, and that uses this curved shape to correct deflection distortion.

According to this invention, internal deflection distortion can be corrected without increasing power consumption, and deterioration of beam spot size can be avoided.

Embodiment FIGS. 5 and 6 show an embodiment of a flat cathode ray tube according to the present invention. This example is applied to a flat cathode ray tube having a configuration similar to that shown in FIGS. 1 and 2 above, with a flat front panel (1), a screen panel (2),
It has a flat glass tube (5) consisting of a funnel (3) and a neck (4), and has a fluorescent light located on the inner surface of the screen panel (2) below the axis (9) of the electron gun (7). The surface (6) is arranged, and the electron beam (8) from the electron gun (7)
is scanned horizontally and vertically on the fluorescent surface (6) by electromagnetic deflection means (not shown). The electromagnetic deflection means in this case is constituted by a deflection yoke with a uniform magnetic field.

In this example, by taking advantage of the fact that the electron beam (8) enters the fluorescent surface at a large incident angle θ, the fluorescent surface (6) is directed against the electron gun (7) in a manner that corresponds to the threading distortion curve. Change the position to the thickness direction of the screen panel (2) and insert the fluorescent surface.
The landing position of the electron beam (8) is changed to correct threading distortion.

That is, as shown in Figure 6, the thickness of the screen panel (2) corresponding to the lower end of the fluorescent surface (6) on the side closer to the electron gun is adjusted so that the center part is inward from both ends in accordance with the curve of the thread winding plan. The screen panel (2) has such a curved surface shape that the fluorescent surface ( 6) is deposited and formed.

Regarding string distortion, since the fluorescent surface (6), that is, the screen is located below and off the axis (9) of the electron gun (7),
The electron beam deflection angle at the bottom edge of the screen is larger than that at the top edge, causing threading distortion. In this case, if a deflection yoke with a uniform magnetic field is used with less deterioration of the beam spot size,
Approximately P% thread-rolling attempts occur at the bottom of the screen. Thread winding distortion rate P
is expressed as follows from FIG.

p - - ) is represented in the center of the bottom edge of the screen. For a 4-inch flat cathode ray tube, P=27
%, θ-14,3°, S = 61.0m, so
The height difference X is x=2.0m. Therefore, the thickness of the glass plate of Screen By Le (2) is made 2.0 mm thicker at the center of the lower edge of the screen than at the left and right edges. Then, this height difference X is made to decrease toward one end of the screen, and the plate thickness is adjusted over the entire screen.

According to this configuration, in the region where threading distortion occurs, the center portion of the phosphor surface (6) is higher inward than both ends, so that the arrival position of the electron beam on the phosphor surface is changed. , Therefore, thread winding distortion is corrected.

In Kamishio, the thickness of the glass plate of the screen panel (2) was changed to give the inner surface of the screen panel (2) the required curved shape, and a fluorescent surface was adhered to this inner surface.
For example, as shown in FIG. 9, the screen panel (2) is formed with a uniform thickness, and a substrate (11) with a curved surface that rises and falls in the direction of incidence of the electron beam in response to the above-mentioned threading distortion is provided.
A fluorescent surface (6) is formed on this substrate surface, and a fluorescent surface (6) is formed on the substrate surface (1).
1) may be arranged on the inner surface of the screen panel (2).

In addition, correction using such a curved surface shape (so-called shape correction)
In the case of large flat cathode ray tubes, the fluorescent surface tends to appear distorted when viewed from the outside. Therefore, in this case, it is preferable to use the shape correction and the conventional circuit correction together.

In addition, although it was applied to correct thread winding distortion on the upper side, other
C can be similarly applied to deflection distortions such as trapezoidal distortion and fan-shaped distortion. Similarly, the present invention can be applied to the configuration of a flat cathode ray tube, especially the position of the fluorescent surface is not limited to the upper side, but is also applicable to other positions.

Effects of the Invention According to the present invention, in a flat cathode ray tube, the fluorescent surface has a curved shape that undulates in the direction of incidence of the electron beam in response to deflection distortion. Distortion can be corrected.Therefore, the deflection distortion of the screen can be corrected without increasing power consumption, and manufacturing costs are also reduced because component costs are not required unlike circuit correction.

Furthermore, compared to correction using a deflection yoke, the beam spot size does not deteriorate.

[Brief explanation of the drawing]

1 and 2 are a partially sectional plan view and a sectional view thereof showing an example of a flat cathode ray tube used for explaining the present invention, FIG. 3 is a perspective view with the fluorescent surface thereof removed, and FIG. The figure is a diagram showing the state of incidence of the electron beam, and FIG. 5 is a diagram showing the state of incidence of the electron beam. A cross-sectional view showing an embodiment of the J4 wire tube, FIG. 6 is a perspective view with the fluorescent surface thereof not shown, FIG. FIG. 9 is a perspective view showing the shape of the surface, and FIG. 9 is a perspective view showing the direction of fluorescence showing another embodiment of the present invention. (1) is a front panel, (2) is a screen panel, (3) is a funnel, (4) is a neck, (6) is a fluorescent surface, and (7) is an electron gun. Figure 3 Figure 4

Claims (1)

[Claims] A flat cathode ray tube comprising a curved fluorescent surface that rises and falls in the electron beam incident direction in response to deflection distortion, and the curved surface shape corrects the deflection distortion.