JPH0760643B2 - Electron gun - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an electron gun of a CRT for a high resolution cathode ray tube, and in particular, it is aimed at high performance.

[Conventional technology]

FIG. 4 (a) is a sectional view showing a conventional in-line type electron gun. In the figure, (1) is a cathode, (2) is a G1 electrode provided in front of the cathode (1), and (3) is The G2 electrode provided on the front surface of the G1 electrode (2), (4) is the G3 electrode further provided on the front surface thereof, and (5) is the G4 electrode further provided on the front surface thereof, and the electrodes (4), (5 ) Constitutes the main lens part, and the G3 electrode (4) is the low-voltage side electrode.
(6) is a bead glass for fixing the above-mentioned electrodes (2) to (5). (7) is a concave portion of the G3 electrode (4), in which three lens holes are linearly arranged.

The conventional electron gun is constructed as described above, and the cathode (1)
The thermoelectrons generated in the G1 electrode (2) that constitutes the three-pole part
And the voltage applied to the G2 electrode (3),
Be accelerated. And the G3 electrode (4) that composes the main lens
The orbit of the electrons is bent by the electric field generated by the voltage difference applied to the G4 electrode (5) and the three electron beams are converged and concentrated at one place.

[Problems to be solved by the invention]

In the conventional electron gun as described above, the main lens unit is configured.
Since the size of the beam passage hole of the G3 electrode (4) is the same for all three passage holes, there is a problem that the focus voltage is different between the outer and inner beams due to the three-dimensional effect of the electric field. there were. Further, as a result, there is a problem that the center beam from the central lens hole and the spot shapes of the outer beams from the lens holes on both sides are different and the resolution is lowered.

The present invention has been made to solve the above problems, and minimizes the focus voltage difference between the center beam and the outer beam, and the center beam and the outer beam have the same beam spot shape. Aim to get an electron gun.

[Means for solving problems]

In the electron gun according to the present invention, the width of the concave portion in the direction perpendicular to the arrangement direction of the three lens holes is narrowed in the central lens hole portion.

[Work]

In the electron gun according to the present invention, since the width of the concave portion of the G3 electrode in the direction perpendicular to the arrangement direction of the three lens holes is narrowed at the central lens hole portion, the longitudinal focusing force of the main lens is increased. The vertical focus voltage of the central beam can be increased without increasing the focus characteristics of the outer beam, and the focus voltages of the central beam and the outer beam can be adjusted to the same value.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 (a) is a sectional view showing an electron gun according to an embodiment of the present invention. FIG. 1 (b) is a view on arrow AB of FIG. 1 (a), and FIG. 8 (8) is a concave portion of the G3 electrode (4) in which three lens holes are linearly arranged. The shape of the recess (8) is
The width in the direction perpendicular to the arrangement direction of the three lens holes is narrowed in the central lens hole portion, and particularly, the central lens hole portion is dented into a rectangle.

In the electron gun configured as described above, the vertical width of the central portion of the recess (8) in which the three lens holes of the G3 electrode (4) forming the main lens portion are arranged, that is, in the lens hole alignment direction. Since the width in the vertical direction is narrow, the vertical curvature of the equipotential surface is larger in the central portion than in the lens hole portions on both sides. Therefore, the vertical focusing power of the central beam is increased, and as a result, the vertical focusing voltage of the central beam can be increased.

Such a variation in the focus voltage of the central beam does not significantly affect the focus voltage of the outer beam. These effects can correct the difference in focus characteristics between the central beam and the outer beam, which is a drawback of the conventional in-line electron gun, and minimize the focus voltage difference.
This makes it possible to align the focus voltage of the three corresponding electron beams of red, green, and blue to the same value, and also to make the shape of the beam spot the same, realizing a high-performance electron gun. it can.

In the above embodiment, when the recess (8) of the G3 electrode (4) was recessed into a rectangle at the central lens hole, both ends of the recess were rounded, but as shown in FIG. The same effect can be expected with a square shape.

Further, as shown in FIG. 3, the same effect can be expected if the lens hole portion at the center of the concave portion (8) is dented into a triangular shape.

Further, in the above embodiment, the G3 electrode is one electrode, but the same effect can be obtained even if a plurality of electrodes are provided.

〔The invention's effect〕

As described above, according to the present invention, since the width of the concave portion of the electrode in the direction perpendicular to the arrangement direction of the three lens holes is narrowed in the central lens hole portion, it corresponds to red, green and blue. The focus voltage and the beam spot shape of the three beams can be made the same, and as a result, a high performance electron gun can be realized and an ultra high resolution CRT can be obtained.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view showing an electron gun of one embodiment of the present invention, FIG. 1 (b) is a view taken along the line AB of FIG. 1 (a), and FIG. 2 is another embodiment of the present invention. A front view of a G3 electrode showing an example, FIG. 3 is a front view of a G3 electrode showing still another embodiment of the present invention, and FIG. 4 (a) is a sectional view showing a conventional in-line electron gun.
FIG. 4 (b) is a view on arrow AB in FIG. 4 (a). (1) …… Cathode, (2) …… G1 electrode, (3) …… G2
Electrode, (4) ... G3 electrode, (5) ... G4 electrode, (6) ...
... Bead glass, (8) ... Recessed portion In the drawings, the same reference numerals indicate the same or corresponding portions.

Front page continuation (72) Inventor Naohisa Yoshida 1 Baba-Zou, Nagaokakyo-shi, Kyoto Mitsubishi Electric Corporation Kyoto Works (56) References JP-A-58-16446 (JP, A) JP-A-58-18842 ( JP, A)

Claims (3)

[Claims] 1. A high-voltage side electrode, a low-voltage side electrode which is arranged facing the high-voltage side electrode and constitutes a main lens part together with the high-voltage side electrode, and which is formed on the side of the low-voltage side electrode facing the high-voltage side electrode, It has three linearly-arranged lens holes through which the electron beam passes, and a concave portion whose width in the direction perpendicular to the arrangement direction of the three lens holes is narrowed at the central lens hole portion. An electron gun characterized by that. 2. The electron gun according to claim 1, wherein the concave portion has a shape in which a width in a direction perpendicular to a direction in which the three lens holes are arranged is dented in a rectangular shape in a central lens hole portion. 3. The electron gun according to claim 1, wherein the concave portion has a shape in which the width in the direction perpendicular to the arrangement direction of the three lens holes is dented in a triangular shape at the central lens hole portion.