JPH0482134A - Raster aging device of cathode-ray tube - Google Patents

Abstract

PURPOSE:To give highly reliable and stable raster-aging to a cathode-ray tube by forming a circuit being connected to a cathode composing an electron gun for the cathode-ray tube in to a constant current circuit. CONSTITUTION:A cathode K composing an electron gun for a cathode-ray tube 9 is connected to a constant current circuit 23. In the raster-aging circuit as the constant current circuit, raster aging is given to the cathode-ray tube by preadjusting the resistance value of each of plural semi-fixed resistors 32a, 32b, 32c and up in the circuit 23 so as to be able to obtain a specified cathode current differing with a kind of cathode-ray tube, and then choosing the predetermined one out of the plural semi-fixed resistors 32a, 32b, 32c and up whose resistance values are respectively preadjusted, so as to be connected to the cathode via a change-over switch 31 in accordance with the kind of cathode-ray tube. When the raster aging is given to the cathode-ray tube by such a device composed as described above, the specified cathode-current differing with the kind of cathode-ray tube can be instantaneously set accordingly by selective connection-changeover operation of the switch 31 to eliminate the need for the resistance value adjustment of a complicated variable-resistor so as to better the workability of the raster aging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) This invention relates to a raster aging device for a cathode ray tube.

(Prior Art) In general, a cathode ray tube, as shown in FIG. ) is emitted from a deflection yoke (5) attached to the outside of the tube (1).
) is deflected by the magnetic field generated by the phosphor screen (
2) is formed in a structure that displays an image on this phosphor screen (2) by horizontally and vertically scanning it. In particular, the electron gun (3) has a cathode (K), this cathode (K
), and a heater (not shown) that heats this cathode (K
) to form an electron beam and accelerate and focus the electron beam toward a phosphor screen (2). ) to (G4)).

In such a cathode ray tube, various tube internal materials are arranged inside the tube (1) for exhaust, and in the latter stage of the exhaust process, the tube (1) is
Activate the cathode (K) of the electron gun (3) located inside the
After exhausting, the getter (not shown) placed in the tube (1) is flashed to increase the degree of vacuum inside the tube, and then an electron beam is emitted from the electron gun (3) to close the phosphor screen (2). ) is scanned horizontally and vertically while aging is performed to ensure stable operation of the cathode ray tube. There is an aging called raster aging.

This is because the vacuum inside the tube is not high enough for cathode (K) activation during the evacuation process, and sufficient activation time cannot be taken due to time constraints during the evacuation process. This is to keep the getter in the intermediate stage, flush the getter and increase the degree of vacuum inside the tube, and then activate it sufficiently to ensure stable operation.

FIG. 3 shows a conventional raster aging device.

This raster aging device has a rotating conveyor (7), and is configured to endlessly rotate and move a plurality of raster aging circuits (8) by the conveyor (7).

Each raster aging circuit (8) is shown in FIG.
As shown for a cathode ray tube (9) equipped with an electron gun having the first to fourth grids (G1) to (G4), the cathode (K) of the electron gun, the heater (H), and the first to fourth grids (G1) ~ (G4) has a circuit network (10) for applying a specified voltage to the cathode (K), the heater (H) and the first, 2nd and 4th grid (Gl), (G2
).

(G4), and a prescribed high voltage is applied to the third grid (G3) via the anode terminal (12) of the cathode ray tube. In particular, a variable resistor (14) is connected to the cathode (K) via an ammeter (13), and the cathode (K) and heater (11)
The cathode current generated when a specified voltage is applied to each of the first to fourth grids (G1) to (G4) is measured by the ammeter (13), and the cathode current is adjusted to the specified value. It is formed in a structure in which the voltage applied to the cathode (K) is adjusted by a resistor (14).

Note that (15a) and (15b) are deflection amplifiers that supply a deflection current to a deflection yoke (16) that generates a magnetic field that deflects the electron beam emitted from the electron gun (3) in the horizontal and vertical directions, respectively. .

In raster aging, the getter-flushed cathode ray tube is loaded onto the conveyor (7) at the loading position of the raster aging device, and a socket (11) is connected to the stem of the cathode ray tube, and a high voltage terminal is connected to the anode terminal (12). Connecting. Then, a prescribed voltage is applied only to the heater (H) to turn on the heater (H) and heat the cathode (K). Conveyor (7)
As the cathode ray tube moves, when the cathode ray tube reaches a predetermined position, the cathode (K), the first to fourth grids (G1) to
(G4) and deflection amplifier (15a), (], 5b
), and in particular, the voltage applied to the cathode (K) is measured by the ammeter (13) using the variable resistor (14).
) is adjusted and applied so that the cathode current specified by Deflected, phosphor screen (2)
This is done while scanning horizontally and vertically.

(Problems to be Solved by the Invention) As mentioned above, in a cathode ray tube, after evacuation, the getter is flushed to increase the degree of vacuum inside the tube, and then a specified voltage is applied to the cathode, grid, etc. of the electron gun to emit electrons. Raster aging is performed to stabilize the operation of the cathode ray tube by emitting an electron beam and scanning the phosphor screen horizontally and vertically with the electron beam. The conventional equipment used for this raster aging has a structure in which multiple raster aging circuits are endlessly rotated by a rotating conveyor, and each raster aging circuit is connected to an electron gun cathode, a heater, and multiple It has a circuit network that applies a specified voltage to the grid, and a variable resistor is connected to the cathode via an ammeter. The cathode current is measured by an ammeter, and the voltage applied to the cathode is adjusted by a resistor so that the cathode current becomes a specified value.

However, the conventional raster aging device described above has a structure in which the cathode circuit operates in a self-biased manner, whereas in cathode ray tubes, the second grid voltage, anode voltage, cutoff voltage, etc. differ depending on the tube type, and the cathode current varies. Therefore, it is necessary to adjust the variable resistor for each tube type, and in some cases,
It will also be necessary to vary the aging time. For this purpose, it is necessary to move the conveyor mounting position of the cathode ray tube and the raster aging start position, and in the case of mixed production of various types and small quantities, switching and adjusting the specified voltage is extremely complicated. In addition, even if the tube type is the same, if raster aging is performed with the resistance value of the variable resistor constant, the cathode current will differ due to variations in the electron gun, so adjust the variable resistor to obtain the specified cathode current. There is a need to.

Furthermore, since the cathode current changes as aging progresses regardless of the type of tube, it is also necessary to adjust it.

In other words, with conventional raster aging equipment, it is extremely difficult to manage the specified cathode current, making it impossible to perform stable and reliable raster aging. There is a problem that switching to aging conditions is complicated and cannot be adequately handled.

This invention was made in view of the above problems,
It is an object of the present invention to configure a raster aging device that can stably perform highly reliable raster aging and has good workability even in the case of mixed production of a wide variety of products in small quantities.

[Structure of the Invention (Means for Solving the Problems) A cathode constituting an electron gun of a cathode ray tube and a plurality of grids that control electron emission from this cathode and accelerate and focus the emitted electron beam are each provided with a prescribed voltage. In the raster aging device for a cathode ray tube, which includes a circuit for stabilizing electron emission from the cathode by applying a current, the circuit connected to the cathode is a constant current circuit.

(Function) As described above, if the circuit connected to the cathode is a constant current circuit, the cathode current, which conventionally changes as aging progresses, can be kept constant, and even if there are variations in the electron gun, etc. It is possible to keep the cathode current constant at all times.

Furthermore, by arranging a plurality of semi-fixed resistors in parallel in the constant current circuit and configuring them to be switched using a change-over switch, the change-over switch can be used to select a predetermined semi-fixed resistor for mixed production of a wide variety of products in small quantities. By connecting them, the cathode current can be determined selectively, and it can be effectively adapted to each type of tube.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

The raster aging device of this embodiment has a structure in which a plurality of raster aging circuits are disposed on a rotating conveyor and rotates endlessly as the conveyor runs, similar to the conventional raster aging device. .

The raster aging circuit is as shown in Figure 1.
A prescribed voltage is applied to each of the cathode (K), heater (H), and multiple grids (first to fourth grids (G1) to (G4) in the illustrated example) that constitute the electron gun of the cathode ray tube (9). This circuit network (20) has a circuit network (20) that
The cathode (K), the heater (H) and the first to third grids (Gl) to (
G3) and a prescribed high voltage is applied to the fourth grid (G4) via the anode terminal (12) provided on the tube side wall of the cathode ray tube (9). ing. In particular, the cathode (K) is equipped with an ammeter (2
2) is connected to the following constant current circuit (23).

Note that (24) is a power source for adjusting the voltage applied to the second grid (G2), and (25) is a power source for adjusting the high voltage applied to the fourth grid (G4).

The constant current circuit (23) consists of an NPN transistor (23)
7), a bias power supply (29) connected to the base of this transistor (27) via a limiting resistor (28),
A constant voltage diode (30) connected to the base of the transistor (27), and a plurality of semi-fixed resistors ( 32a) (32
b) , (32c), . . . , and the collector of the transistor (27) is connected to the ammeter (22).

Also, this raster aging circuit is used for cathode ray tube (9)
Deflection amplifiers (33a), (3ab) supplying horizontal and vertical deflection currents to the deflection yoke (16) mounted on the
has.

In this raster aging circuit, its constant current circuit (2
3) A plurality of semi-fixed resistors (32a) and (32b)
).

(32e), ... are adjusted in advance to obtain a specified cathode current that differs depending on the tube type, and the adjusted plural semi-fixed resistors are switched by the changeover switch (31) according to the tube type. Vessels (32a), (32b) (
32c) Raster aging is performed by selecting and connecting a predetermined resistor from .

Therefore, when raster aging is performed using the raster aging device configured as described above, the switch (31) is used to select a specified cathode current that differs depending on the tube type.
Settings can be made instantaneously by switching selections, eliminating the need for the complicated adjustment of variable resistors that was conventionally performed, and improving the workability of raster aging. In addition, since the constant current circuit (23) maintains the preset cathode current, it is possible to prevent changes in the cathode current due to variations in the electron gun that conventionally occur.
In addition, changes in cathode current that occur as aging progresses can be prevented, and all problems of conventional raster aging devices can be solved.

[Effects of the Invention] A specified voltage is applied to each of the cathode and a plurality of grids constituting the electron gun of the cathode ray tube [7] In a raster aging device that performs raster aging, if the circuit connected to the cathode is a constant current circuit. Because the constant current circuit can maintain a preset cathode current, it is possible to prevent changes in cathode current that occur due to variations in conventional electron guns, and also to prevent changes in cathode current that occur as aging progresses. can be kept constant, making it possible to perform highly reliable and stable raster aging. In addition, for example, by arranging semi-fixed resistors in parallel and configuring them to be switched by a changeover switch, it is possible to instantly set a specified cathode current that varies depending on the tube type by selecting the changeover switch.
Raster aging can be performed with good workability when applied to mixed production of a wide variety of products in small quantities.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a raster aging circuit which is a main part of a raster aging device for a cathode ray tube according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a cathode ray tube, and FIG. 3 is a diagram showing a conventional raster aging circuit. Diagram showing the configuration of the aging device, No. 4
The figure shows a conventional raster aging circuit. 9... Cathode ray tube, 20... Raster aging circuit, 21... Socket, 22... Ammeter, 23...
...constant voltage circuit, 27...NPN transistor,
29... Bias power supply, 30... Constant voltage diode, 31... Changeover switch, 32a, 32b, 32c -... Semi-fixed resistor, 33a
, 33b... Deflection amplifier, G1... First grid, G2... Second grid, G
3...3rd grid, G4...4th grid, H.
・Heater K...Cathode, Fig. 2

Claims (1)

[Claims] A cathode constituting an electron gun of a cathode ray tube and a plurality of grids that control electron emission from the cathode and accelerate and focus the emitted electron beam are respectively applied with prescribed voltages to emit light from the cathode. A raster aging device for a cathode ray tube comprising a circuit for stabilizing electron emission, characterized in that the circuit connected to the cathode is a constant current circuit.