JPS61277136A - Raster ageing device for color picture tube - Google Patents

Abstract

PURPOSE:To perform raster ageing effectively, by controlling voltages applied to the three cathodes installed within a color cathode-ray tube respectively, and feeding stable and activated currents with specific values to the three cathodes respectively. CONSTITUTION:A specific set voltage Vka1 is set by a variable resistor 9a, and a detected voltage Vka2 is applied to a cathode 7a, when, the value of the detected voltage Vka2 is detected by a voltage detector 11a and input to IC 12a. At the same time, the value of the set voltage Vka1 is also input to IC 12a, where the set voltage Vka1 and the detected voltage Vka2 are compared, and a voltage increase or decrease signal Sa1 is output to the base of a transister 13a to make the detected voltage Vka2 equal to the set voltage Vka1. And, the voltages of bases of transistors 10a1 and 10a2 are controlled by the transistor 13a to which the voltage increase or decrease signal has been input, and the detected voltage Vka2 of the cathode 7a is controlled to be equal to the value of the set voltage Vka1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a raster aging device for a color picture tube that supplies an activation current to a cathode built into the color picture tube.

[Technical background of the invention and its problems] Generally, in order to activate the surface of the cathode installed in a color picture tube immediately after manufacture, aging is performed by supplying an activation current to the cathode under predetermined conditions. .

One type of aging is performed by supplying an activation current only inside the electron gun, and the other is performed by supplying an activation current to the cathode under the same operating conditions as when an actual color picture tube is operating. (hereinafter simply referred to as raster aging). Since this raster aging is performed in the same way as the actual color picture tube operates, it is possible to improve and stabilize the color picture tube's emission characteristics, stabilize its withstand voltage characteristics, and add stray emission inspection functions. In this respect, it is superior to the aging described above.

Conventionally, such raster aging has been applied to the anode 2 and deflection yoke 3 of the color picture tube 1, as shown in FIG.
, voltage is applied to the grids 4a14b and 4c1 and the heater 5 from the television chassis 6 under the same conditions as the operation of an actual color picture tube, and current is supplied from the raster aging device A to the cathodes 7a, 7b and 7G to obtain an actual color image. Similar to the operation of the tube, an electron beam is emitted from the electron gun 8, and while being deflected, it hits the entire phosphor screen 1a, causing the phosphor screen 1a to emit light.

However, in such a conventional raster aging device A, since the activation currents supplied to the cathodes 7a, 17b and 7C are controlled by one control device, currents with the same current value are applied to the cathodes 7a, 7b and 7C, respectively. It was not possible to supply an optimal activation current to the cathodes 7a, 7b, and 7C, which had different cutoff characteristics, and was insufficient to obtain an aging effect.

In addition, a high-definition color picture tube with a phosphor screen with long afterglow characteristics,
When raster aging is performed using such a conventional raster aging device @A, the electron beam emitted from the cathode due to the activation current, which has the above-mentioned drawbacks, hits the phosphor screen with long afterglow characteristics. A large amount of electrical charge often occurs, causing a phenomenon called "burn-in" on the phosphor screen.

Therefore, in order to compensate for the above-mentioned drawbacks, raster aging using picture tube drive circuit B is performed as shown in Figure 5, but even though raster aging needs to be performed under the same conditions for 30 minutes, First, since there is no control section to control the activation current, fluctuations in the primary voltage that operates this picture tube drive circuit B cause the activation current to become unstable and insufficient to obtain an aging effect. However, if the cutoff characteristics of the cathodes 7a, 7b and 7C are extremely different from each other, this effect will not be obtained.

[Objective of the Invention] The present invention has been made in view of the above circumstances, and provides a stable activation current at a predetermined value to each of the three cathodes installed in a color picture tube, thereby effectively reducing raster aging. It is an object of the present invention to provide a raster aging device for a color picture tube that can perform color picture tube raster aging.

[Summary of the Invention] That is, according to the raster aging device for a color picture tube of the present invention, in the raster aging device that supplies an activation current to a cathode installed in the color picture tube, three cathodes installed in the color picture tube A voltage setting section that sets a voltage to be applied to each of the cathodes, a voltage application section that can simultaneously apply a voltage to each of the three cathodes, and detecting the voltage applied to each of the three cathodes. a voltage detection section; a voltage comparison section that compares the voltage applied to each of the three cathodes with the voltage set by the voltage setting section and outputs a voltage increase/decrease signal; and a voltage comparison section that outputs a voltage increase/decrease signal; and a voltage control section that inputs a signal to control the applied voltage of the voltage application section, and controls the activation current supplied to each of the three cathodes, thereby controlling the activation current supplied to each of the three cathodes. This enables effective raster aging by supplying a stable activation current at a predetermined value to each of the three cathodes.

[Embodiments of the Invention] Hereinafter, details of embodiments of the present invention will be described based on the drawings.

FIG. 1 is a diagram for explaining one embodiment of the present invention, FIG. 2 is a diagram showing the relationship between cut-off voltage and emission current,
FIG. 3 is a circuit diagram of the raster aging device in this embodiment.

First, as shown in FIG. 1, the color picture tube raster aging device C of this embodiment includes a cathode current automatic tracking device 8a that supplies an activation current to the cathode 7a of the color picture tube 1, and an activation current to the cathode 7b. and an automatic cathode current tracking device 8C that supplies an activation current to the cathode 7C.

Furthermore, as shown in FIG. 2, the cutoff voltage and emission current of the color invasive tube 1 are in a proportional relationship, so controlling the activation current when performing raster aging is done by adjusting the voltage applied to the cathode. Just control it.

Therefore, as shown in FIG. 3, the cathode current automatic tracking device a includes a variable resistor 9a that sets the voltage to be applied to the cathode 7a, transistors 10a+ and 10az that apply the voltage to the cathode 7a, and a The voltage value Vka+ (hereinafter referred to as set voltage Vk) is set by the voltage detection unit 11a that detects the applied voltage and the variable resistor 9a.
a+) and the voltage value Vka2 detected by the voltage detection section
(hereinafter referred to as detection voltage Vka2) and outputs a voltage increase/decrease signal SaI, and a voltage increase/decrease signal S
a I is input and transistors 10a+ and 10a2
A transistor 13a that controls the detection voltage ■kaz applied to the cathode 7a from
It is composed of. Further, the automatic cathode current tracking device 8b and the automatic cathode current tracking device 8C are also configured with the same circuit as the automatic cathode current tracking device 8a.

The operation of the raster aging apparatus C of this embodiment configured as described above will be explained.

When an activation current controlled to a predetermined value is passed through the cathode 7a, the voltage applied to the cathode 7a may be controlled to a predetermined value as described above. In this embodiment, a predetermined set voltage Vka+ is set by the variable resistor 9a,
A detection voltage Vkaz is applied to the cathode 7a, and at this time, the value of this detection voltage ■kaz is detected by the voltage detection section 11a, and this value is input to the IC 12a. Furthermore, the value of detection voltage Vka2 is also input to IC12a, and IC12a
The set voltage ■kal is compared with the detected voltage Vkaz, and a voltage increase/decrease signal S81 is output to the base of the transistor 13a so that the detected voltage Vka2 becomes the set voltage Vka+.
The transistor 13 to which this voltage increase/decrease signal Sa+ is input
By controlling the voltages at the bases of transistors 10al and 10a2 using a, the detection voltage Vkaz of the cathode 7a is controlled to become the set voltage Vka+.

Further, the cathode 7b and the cathode 7C are similarly operated by the automatic cathode current tracking device 8b and the automatic cathode current tracking device 8c.

Therefore, a current of a predetermined value set to each of cathodes 7a, 7b, and 7c is stably supplied.

[Effects of the Invention] As explained above, according to the raster aging device for a color picture tube of the present invention, by controlling the voltage applied to each of the three cathodes installed in the color picture tube, A stable activation current at a predetermined value is supplied to each of the cathodes, and raster aging can be effectively performed.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of the present invention, FIG. 2 is a diagram showing the relationship between cut-off voltage and emission current,
FIG. 3 is a circuit diagram of a raster aging device in this embodiment, and FIGS. 4 and 5 are diagrams for explaining a conventional raster aging device. C・・・・・・・・・・・・・・・・・・・・・
Raster aging device 8a, 8b, 8C-j:t')-1" R flow automatic tracking device 9a......... Variable resistor ioa +, 10a 2...transistor 1
1a・・・・・・・・・・・・・・・・・・Voltage detection section 12a・・・・・・・・・・・・・・・・・・
・・IC13a・・・・・・・・・・・・・・・・・・
・・・Transistor Sa I・・・・・・・・・・・・
・・・・・・・・・Voltage increase/decrease signal applicant Toshiba Corporation Patent attorney Suyama Sa - Niemi,, N-o/Kushipum closing section Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) In a raster aging device that supplies activating current to three cathodes installed in a color picture tube, voltage setting sets the voltage to be applied to each of the three cathodes installed in the color picture tube. a voltage applying section capable of simultaneously applying a voltage to each of the three cathodes; a voltage detecting section detecting the voltage applied to each of the three cathodes; a voltage comparison section that compares the applied voltage with the voltage set by the voltage setting section and outputs a voltage increase/decrease signal; and a voltage comparison section that inputs the voltage increase/decrease signal of the voltage comparison section to adjust the voltage applied to the voltage application section. A raster aging device for a color picture tube, comprising: a voltage control section for controlling the activation current supplied to each of the three cathodes.