JP2573688Y2 - Cathode ray tube - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus mechanism for a monochrome cathode ray tube such as a projection type cathode ray tube.

[0002]

2. Description of the Related Art FIG. 2 is a schematic view showing a conventional means for converging an electron beam of a monochrome cathode ray tube and its peripheral portion.
In the figure, reference numeral 11 denotes a neck constituting an envelope of a cathode ray tube .
Parts, 14 electron gun, 14a heaters, 14b electron emission cathode, 14c are controlled for G ₁ grid, 14d are electron acceleration G ₂ grids, 21, 22 and 14h multistage focusing electrode, 14i are anode potential connection electrode , 14j are bead glasses for fixing the respective electrodes. Electrode 21 and electrode 14
h is connected to have the same potential, and is usually set to the anode potential. By adjusting the voltage (lower than the anode potential) applied to the electrode 22, the diameter of the electron beam on the face surface of the cathode ray tube (the surface coated with the phosphor) is optimized. The electron gun of FIG. 2 is a UPF (uni-potential).
-Focus) The electron gun is called an electron gun, and its focusing means is an electrostatic focus type comprising a multistage focusing electrode. In this case, a potential gradient is formed by a difference between potentials applied to the electrodes 21, 22, and 14h and a gap between the electrodes, and this potential gradient gives a converging action and a diverging action to the electron beam. This is also called an electron lens because it has the same effect on electrons as the optical lens does on light. This electronic lens is expressed with the same characteristics as the optical lens. One is the magnification of the lens, and the other is the aberration. These two characteristics are necessary elements for focusing the electron beam to a small spot. FIG. 3 is a schematic view showing an electron beam converging means of another conventional monochrome cathode ray tube and its peripheral portion. In the figure, 11, 14a, 14b,
14c, 14d, 14j and 14i are the same as those in FIG. Reference numeral 32 denotes an electrode, and 31 denotes a focus magnet that generates a magnetic field inside the electrode 32. The cathode ray tube shown in FIG. 3 has no electrostatic focusing mechanism. An anode voltage is applied to the electrode 32, and focus adjustment is performed by moving the focus magnet 31 which is usually made of a permanent magnet back and forth along the axis. Alternatively, the focus adjustment is achieved by passing a current through a coil attached to the focus magnet 31 to weaken the magnetic field generated by the magnet. A device that performs such focus adjustment is called an electromagnetic lens, and a magnetic field causes electrons to undergo a converging action toward the axial center of the electron gun at the same time as a rotational motion.

[0003]

The conventional electron beam converging means is constructed as described above. For a UPF electron gun (FIG. 2), the diameter of the electron lens is limited by the diameter of the neck portion 11. It can not be made large, and the network
Since the number of voltage supply pins (see reference numeral 14k in FIG. 1) cannot be increased due to the limitation of the diameter of the lock portion 11, the number of multi-stage focusing electrodes constituting the electron lens is increased to smoothly change the potential distribution. Therefore, it was not easy to reduce the aberration of the electron lens. Further, as for the electron gun of the electromagnetic lens (FIG. 3), since the focus magnet is attached outside the neck portion 11, the aperture and the focal length can be selected relatively freely. There is a problem that it is difficult to align the axis of the electron beam with the electron beam and the cost increases. This invention has been made to solve the above problem, and has as its object to reduce the spot diameter of an electron beam on the face surface of a cathode ray tube by using inexpensive means.

[0004]

A monochrome cathode ray tube according to the present invention comprises an electron beam emitting section, a control section, and a plurality of multistage.
Electron gun having electrostatic lens by focusing electrode, this electron gun
The neck part enclosed is provided outside this neck part
And an electromagnetic lens, wherein each of the multistage focusing electrodes is
The anode potential is controlled by a resistor built into the neck.
The operating voltage is divided and the electromagnetic lens is
A tape-shaped focusing coil wound around the neck
Have a focal length longer than the focal length of the electrostatic lens.
A cathode ray tube characterized in that:

[0005]

In this invention, the electric field distribution of the electrostatic lens is relatively easily raised smoothly to the anode potential to reduce aberrations, and the focusing coil has a long focal length and the current passing therethrough is adjusted to adjust the current through the cathode ray tube. Creates a perfect electron beam spot on the face of the device.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. Network In this figure, 11 is to keep the electron gun
The reference numeral 12 denotes a converging coil in which a tape-shaped conductor is spirally wound around the outside of the neck 11, and 13 denotes an elongated single built-in high-resistance element. 14 is an electron gun, 14a is its heater,
14b is an electron-emitting cathode, 14c are controlled for G ₁ grid, 14d is G ₂ grid for electron acceleration. 14e,
14f, 14g and 14h are multi-stage focusing electrodes, 14j is a bead glass for fixing the electron gun 14, 14i is an anode potential connection electrode, and 14k is a plurality of voltage supply pins. A voltage sequentially lower than the anode potential is applied to each of the multi-stage focusing electrodes,
The resistance is divided by the built-in high resistance body 13 and applied. As described above, the cathode ray tube of the present invention has two electron beam converging means: the electromagnetic lens (converging coil 12) and the electrostatic lens (multistage converging electrodes 14e, 14f, 14g, 14h). In such a configuration, the multi-stage focusing electrode 14
e, 14f, 14g, and 14h, the electron beam is narrowed down by an electrostatic lens having a smooth potential distribution in the space, and the face of the cathode ray tube is completely formed by an electromagnetic lens having a magnetic field generated by an external focusing coil 12. Make an electron beam spot on the surface. As described above, since the external coil is combined with the electron gun of the electrostatic lens, the focus characteristics are better than the conventional electrostatic lens, and the focus adjustment becomes easier. Further, the multi-stage focusing electrodes 14e, 14f, 14
g and 14h are connected to respective points of a desired length of one elongated built-in high-resistance body 13 so that a large number of supply potentials can be selected at low cost without increasing the number of voltage supply pins 14k. Since the voltage can be supplied in such a manner, the electric field distribution of the electrostatic lens can be smoothly increased from the potential at or near the ground to the anode potential, so that the aberration of the electron lens can be reduced. Further, a focusing coil 12 having a long focal length for fine adjustment is wound around the neck portion 11 in a tape shape, and the electron beam and the focusing coil are easily obtained in a state where the axes are aligned.

[0007]

As described above, according to the present invention, the convergence means of the electron gun of the monochrome cathode ray tube is provided with a multi-stage focusing electrode provided with the anode potential divided and supplied, and a multi-stage focusing electrode provided outside the neck portion. It is composed of a combination of an electromagnetic lens with a converging coil having a focal length longer than the focal length of the electrostatic lens with electrodes. A cathode ray tube can be supplied.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a converging means of an electron gun, which is a main part of a monochrome cathode ray tube according to the present invention, and a peripheral part thereof.

FIG. 2 is a schematic view showing a converging means of an electron gun of a conventional monochrome cathode ray tube and its peripheral portion.

FIG. 3 is a schematic view showing a converging means of an electron gun of another conventional monochrome cathode ray tube and its peripheral portion.

[Explanation of symbols]

11 neck portion 12 focusing coil 13 built-in high resistance element 14 electron gun 14a heater 14b electron emission cathode 14c control G ₁ grid 14d electron acceleration G ₂ grid 14e multi-stage focusing electrode 14h multi-stage focusing electrode 14i anode potential connection electrode 14j bead glass 14k voltage supply pin

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01J 29/58 H01J 29/96 H01J 29/66 H01J 29/48 H01J 29/50

Claims (1)

(57) [Scope of request for utility model registration] 1. An electron beam emitting unit, a control unit, and a plurality of
An electron gun having an electrostatic lens with a multistage focusing electrode, a neck portion enclosing the electron gun, and a portion provided outside the neck portion.
Each of the multi-stage focusing electrodes,
The anode voltage is controlled by a resistor built into the neck.
The operating voltage is supplied by dividing the position, and the electromagnetic lens is
Is it a tape-shaped focusing coil wrapped around the neck
Rannahli, cathode ray tube, characterized in Rukoto to have a longer focal length than the focal length of the electrostatic lens.