JPS6344861Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a multicolor cathode ray tube device that controls emission color by modulating beam velocity.

[Background of the invention and drawbacks of conventional technology]

2. Description of the Related Art Multicolor cathode ray tube devices are used as observation display devices or information display devices for computers and the like.
Beam penetration type CRT is one type of multicolor cathode ray tube (CRT). This CRT has, for example, multiple layers of phosphors that emit light of different colors coated on the inner surface of the face plate. To change the color of the emitted light, the speed of the electron beam is changed, the depth of penetration of the electron beam into the phosphor is controlled, and the light emitting part is changed.

In the conventional technique of changing the electron beam speed,
Since the accelerating voltage of the CRT is directly controlled, the deflection sensitivity, focal position, etc. change as the emitted light color is switched. Therefore, each time the emitted light color is switched, corrections for deflection sensitivity, focus, etc. are performed at the same time. However, in order to perform these corrections, the deflection circuit and the electron gun circuit have become complicated and expensive. Furthermore, it was difficult to accurately control the size and position of the display.

[Purpose of invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a multicolor cathode ray tube device that controls emission color by changing electron beam speed without affecting deflection sensitivity and focus control.

[Summary of the idea]

According to the present invention, a CRT includes a plurality of phosphors emitting light of different colors provided on the inner surface of the face plate,
It includes a first electrode provided on the electron gun side of these phosphors, and a second electrode provided near the first electrode on the electron gun side. Then, the electron gun and the second
While maintaining the potential difference between the electrodes almost constant, the first
The color of the emitted light is controlled by controlling the potential difference between the second electrode and the second electrode. Therefore, the spatial electric field of the deflection system provided between the electron gun and the second electrode and the beam passing speed are approximately constant regardless of the switching of the emission color, and the deflection sensitivity and beam focusing are not affected.

[Example of idea]

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the accompanying drawing, a CRT 10 has phosphor layers 14 and 16 of different emission colors on the inner surface of a face plate 12. These phosphor layers are
It may be a collection of particles in which the core is a first phosphor and the core is surrounded by a second phosphor. An electron gun 18 is provided within the CRT 10 at opposite ends of the face plate 12. This electron gun 18 is composed of a cathode, a brightness control electrode, a focus control electrode, etc., and is controlled by an electron gun circuit 20. A back electrode 22, which is a first electrode, is provided on the electron gun 18 side of the phosphor layer 16, and its voltage is controlled by a color control circuit 24. A mesh electrode 26, which is a second electrode, is provided near the back electrode 22 and on the electron gun 18 side, and this electrode 26 is grounded. Vertical and horizontal deflection plates 28 are provided between the electron gun 18 and the mesh electrode 26 to deflect the electron beam from the electron gun 18 in accordance with the output signal from the deflection circuit 30. The deflection system may be an electromagnetic deflection system instead of the electrostatic deflection system as in the embodiment. Note that since the mesh electrode 26 is at ground potential, the electron gun 18 is maintained at an appropriate negative potential, and the color control circuit 24 generates a variable positive voltage.

Next, the operation of the attached diagram will be explained. The electron beam accelerated by the potential difference V1 between the electron gun 18 and the mesh electrode 26 is deflected by the deflection plate 28 and reaches the mesh electrode 26. This electron beam is accelerated by the potential difference V2 between the mesh electrode 26 and the back electrode 22, and reaches the phosphors 14 and 16. Since the acceleration due to the potential difference V2 is shorter and more rapid than the acceleration due to the potential difference V1, the spatial electric surface between the back electrode 22 and the mesh electrode 26 becomes a substantially parallel plane,
The position of the beam that has reached the mesh electrode 26 is projected onto the phosphors 14 and 16 as is, almost regardless of the change in the potential difference V2 for switching the beam entry speed. The depth of entry into the phosphors 14 and 16 is controlled only by changing the potential difference V2 by the color control circuit 24. That is, when the potential difference V2 is large, the electron beam penetrates into the phosphor layer 14 through the phosphor layer 16, causing the phosphors 14 and 16 to emit light. Moreover, when the potential difference V2 is small, the electron beam
6 and causes this phosphor layer 16 to emit light. Note that the afterglow time can also be controlled depending on the characteristics of the phosphor. If there is a slight change in the display size due to a change in the potential difference V2, it can be compensated for by controlling the voltage of the potential difference V1 at the same time, and there is no need to control the deflection system.

[Effect of idea]

As described above, according to the present invention, the potential difference between the second electrode (mesh electrode) and the electron gun can be kept almost constant regardless of the beam speed, so the spatial electric field of the deflection system and the beam passing speed are kept constant, which improves the deflection sensitivity. and focus control are unaffected. Therefore, it is not necessary to provide a compensation circuit in the electron gun circuit and the deflection circuit, and the circuit can be made simple and inexpensive.

[Enrichment of examples]

Although only one preferred embodiment of the present invention has been described above, those skilled in the art will understand that various modifications can be made without departing from the gist of the present invention. For example, the first electrode may be a thin porous metal or a metal mesh. Further, the second electrode potential may be a floating potential other than the ground potential. Furthermore, when the first electrode potential is fixed, the potentials of the second electrode and the electron gun may be changed by the same amount in response to color switching. Moreover, three or more types of phosphors may be used.

[Brief explanation of the drawing]

The attached drawing shows a preferred embodiment of the present invention. 10: Cathode ray tube, 12: Face plate, 1
4, 16: phosphor, 18: electron gun, 22: first electrode, 24: color control circuit, 26: second electrode.

Claims (1)

[Scope of utility model registration request] A cathode ray comprising a plurality of phosphors emitting different colors of light provided on the inner surface of a face plate, a first electrode provided on the electron gun side of the phosphors, and a second electrode provided on the electron gun side of the first electrode. A multicolor cathode ray tube, comprising: a tube; and a color control circuit that controls the potential difference between the first electrode and the second electrode while maintaining the potential difference between the electron gun and the second electrode of the cathode ray tube substantially constant. Device.