JPS5916387B2 - flat cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flat cathode ray tube, and its main purpose is to improve the Rusk trapezoidal distortion on the screen.

Conventionally, flat cathode ray tubes have been proposed in which the electron gun is arranged parallel or substantially parallel to the phosphor film surface and the depth is reduced.

This will be explained with reference to FIGS. 1 and 2.

That is, 1 is a nearly rectangular parallelepiped envelope, with one side including the short side 1
A neck portion 2 is formed extending outward from point a, and an electron gun 3 is disposed inside the neck portion 2.

The inner surface of the upper surface (face plate) 1b of the envelope 1 has a fluorescent film 4. Thin metal films 5 are sequentially formed to form a face layer) 1b.
A conductive film 6 is formed on the inner surface of the lower surface (backplane) 1e facing the.

Then, an appropriate voltage is applied to the metal thin film 5 and the conductive film 6 to form an electric field in the envelope 1, and the electron beam emitted from the electron gun 3 is bent toward the face plate Nb side, causing the fluorescent film 4 to emit light. Let's do it 51/c.

However, since the electron beam emitted from the electron gun 3 is linearly deflected in rows 5 and the deflection angle is constant, it forms a fan-shaped raster 7.

Therefore, many proposals have been made to improve this.

For example, by changing the amplitude of the deflection waveform so that the raster becomes rectangular on the face plane Nb, or by providing a deflection correction unit that performs deflection correction using an electric or magnetic field in front of the deflection unit, the Rask fan-shaped distortion is corrected. It is something.

However, these have five drawbacks, such as complicated structures, and complicated adjustments and operations.

The present invention has been proposed in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a flat cathode ray tube that can improve raster flatness distortion with a simple structure.

The present invention will be explained below with reference to the drawings shown in FIGS. 3 to 7.

The same reference numerals as in FIGS. 1 and 2 indicate the same parts.

In the figure, 8a and 8b have the face plate 1b as the upper surface, and the face plate 1 is facing toward the electron beam traveling direction.
The opposing surfaces of magnets 8a and 8b are set as N and S poles, respectively, so that the strength of the magnetic field is small in the electron beam traveling direction.

(A triangular magnet is used in the illustrated example.) This operation will be explained below.

Figures 5 to 7 are x, -x, , x2- in Figure 4.
x2. This shows the x3-x3 cross section, showing the deflected electron beam A.

B and C represent the forces received in the direction of the face plate 1b due to the electric fields within the face plate 1b and the back plate 1c, respectively, and the forces received at the same time due to the magnetic fields of the magnets 8a and 8b.

However, FIGS. 5 to 7 do not show the force exerted on the electron beam due to the electric field.

Only the force due to the magnetic field is shown.

The point where the strength of the magnetic fields received from the magnets 8a and 8b is equal to the plane (Y-Y in the diagram) containing the lines of magnetic force that enter the inside of the envelope 1 linearly from the N pole of the magnet 8a to the S pole of the magnet 8b. (Illustrated 2-2), and are divided into regions I and n, respectively.
, m, IV.

In region I, the magnetic field is directed from the side surface 1d to the face plate Nb.

Therefore, the electron beam A1 in this region is perpendicular to the magnetic field and receives a force in the direction of the side surface 1d.

In region (3), the magnetic field is directed from the side surface 1d to the back plate 1c.

Therefore, the electron beam B1 in this region. C,&'! It is perpendicular to the magnetic field and receives a force in the opposite direction to the side surface 1d.

Similarly, in area ■, back play) 1c and that side 1e
Since the magnetic field is directed to , the electron beam in this region B,'
, C,' are perpendicular to this magnetic field and in the opposite direction to the side surface 1e.In region ■, the magnetic field is directed from the face plate Nb to the side surface 1e, so the electron beams A and I in this region are perpendicular to this magnetic field and in the opposite direction to the side surface 1e. Receives force in direction 1e.

Therefore, the electron beams A1 and A; are on the side surfaces 1d and 1, respectively.
Force is applied in the e direction, and electron beams B, , C, and B;
, C; are each subjected to forces in directions approaching each other.

Arrows indicate the direction of the force exerted by the electron beam in each region.

When the electron beam further advances and reaches the X2-X2 cross section, the electron beam B2. B
'2 receives forces in the directions of side surfaces 1d and 1e, and electron beams c2. c' receives a force in the opposite direction to the side surfaces 1d and le.

As the trochanter beam further advances and reaches XX3-X3I,
There is no magnetic field component perpendicular to the face plate 1b, or even if it exists, it is small, so the electron beams C3, C; are not influenced by the magnets 8a and 8b and are bent only by the electric field.

Therefore, electron beam A draws a bright line similar to a raster electron gun.
The deflection angle is expanded by traveling in regions I and IV, and the electron beam C, which draws an emission line far from the electron gun, is in region ■
, ■, the deflection angle is reduced.

Draw the central part of the raster between electron beams A and C (electron beam B has a deflection angle that is shortened in areas ■ and ■, but is widened in areas I and IV, so it is deflected as a whole. The corners can be made the same as without the magnets 8a, 8b.

Therefore, flattening distortion of the raster can be removed simply by placing a magnet on the side, resulting in a simple structure and easy adjustment and operation.

Note that the first invention obtains a rectangular raster by linear deflection, but due to the non-uniformity of the magnetic field of the magnet, the dimensions of the envelope, etc.
If distortion correction is not sufficient.

A complete rectangular raster can be obtained by using other means such as changing the amplitude of the deflection waveform.

Even in such a case of 5, the correction amount is small, so that the device does not become decoupled.

Further, the present invention is not limited to triangular magnets, and the strength of the magnetic field may be changed by, for example, separating the magnets in the direction in which the electron beam travels.

As described above, according to the present invention, the structure is simple.

A rectangular raster can also be obtained by linear deflection, which is easy to adjust and operate, and can reduce costs.

[Brief explanation of the drawing]

1 and 2 are a side sectional view and a plan view of a flat cathode ray tube, FIGS. 3 and 4 are a partial side sectional view and a plan view of a flat cathode ray tube embodying the present invention, and FIG. FIG. 7 is a drawing for explaining the present invention in detail, and FIG. 5 is a diagram showing the X, -X, and
6 is a sectional view taken along the line X2-X2 in FIG. 4, and FIG. 7 is a sectional view taken along the line X3-X3 in FIG. 4. 1...Envelope%1b...Face plate. 1c...Back plate, la, 1e...
··side. 3... Electron gun, 4... Fluorescent film, 5...
...Metal thin film. 6... Conductive film, 8a, 8b... Magnet.

Claims (1)

[Claims] 1. A face plate I/C electron beam is inserted between the face plate and the back plate into an envelope consisting of a face plate having a fluorescent film and a metal film on the inner surface, and a back plate having a conductive film on the inner face, which are arranged facing each other. In the case where the electron gun is arranged at 5 so as to be able to supply the beam, there is a magnetic field on the side surface of the envelope adjacent to the face plate and parallel to the axial direction of the electron gun, where the strength of the magnetic field is small in the direction in which the electron beam travels. A pair of magnets, with the face plate as the upper surface, the left side KN pole and the right inner side KS with respect to the direction of movement of the electron beam.
A flat cathode ray tube characterized in that the tubes are arranged opposite each other so as to form poles.