KR950015072B1 - Crt voltage characteristics testing device - Google Patents

Abstract

The test voltages are applied to a CRT sequentially to test a CRT. The apparatus includes a power supply(2) for providing various kinds of withstand voltage to a CRT, a switch(1) for applying test withstand voltage to a CRT, a controller(CTR) for controling the switch(1), and a metering means(3) for detecting applied voltage to a CRT, a current and voltage variation due to the applied withstand voltage.

Description

Method and device for testing withstand voltage characteristics of CRT

1 is a circuit diagram showing the configuration of a conventional SE test apparatus.

2 is a circuit diagram showing an embodiment of the withstand voltage characteristic test apparatus according to the present invention.

* Explanation of symbols for main parts of the drawings

1: switching means 2: power supply

3: metering means 4: protecting means

CTR: control means

The present invention relates to the manufacture of CRT, and more particularly, to a method for testing its withstand voltage characteristics and a test apparatus using the method.

Since a high voltage of several tens of KV is applied to the CRT, a high voltage phenomenon, such as leakage, spark, glow, or the like, which does not appear in a general voltage state, is generated. In particular, the distance between the unit electrodes constituting the electron gun assembly is very close to 1 or 2 mm, so that the insulation between the unit electrodes is insufficient, and contamination of foreign substances such as dust, dropped electron-emitting materials or phosphors, etc. In particular, it is a very important management item for maintaining the quality, which is the characteristic of withstand voltage, in the color-brown tube of a complicated configuration in which the R, G, and B electrodes are arranged in parallel.

Such high pressure phenomena include stray emission (SE) that emits electrons and emits light abnormally outside of the cathode, grid emission (GE) that emits light abnormally between electrodes, and high voltage. Field emission (FE), etc., in which residual gas in the tube is ionized and emits light, neck emission (Neck GLow; NG), and leakage between electrodes (Grid Leakage (GL)).

In the prior art, for example, the circuit diagram SE shown in FIG. This circuit adjusts the G3 voltage (EC3) and the anode voltage (Eb) while grounding the other electrodes to measure the voltage at which the light emission occurs in the CRT with a meter (M; M). It is a configuration to grasp.

Such SE test circuits are not protected against high pressure at all, and circuit breakage is not only frequent, but also SE test is performed as the name suggests, and other high pressure phenomena, for example, GE or FE cannot be inspected at all. The reason why the conventional inspection circuit can inspect only a single characteristic such as SE is because the applied voltage and the connecting electrode are different when a different high voltage phenomenon is to be tested. Accordingly, conventionally, only the SE inspection circuit was configured as part of the static characteristic test apparatus, and only the quantity and defect of the CRT were tested, and the precise analysis was not possible at all. Therefore, the pressure resistance characteristic defect can be determined, but the cause can not be determined, and if necessary, the vacuum of the CRT was destroyed and the microscopic observation was inevitable. As such, the root cause of the breakdown voltage characteristic cannot be determined, resulting in a problem in that the reliability of the quality of the CRT that is shipped can not be guaranteed.

It is an object of the present invention to provide a test method capable of testing a plurality of items of withstand voltage characteristics in view of such a conventional problem.

Another object of the present invention is to provide a withstand voltage characteristic test apparatus implementing such a test method.

In order to achieve the above object, the withstand voltage characteristic test method according to the present invention is characterized by sequentially testing a plurality of withstand voltage characteristic items by selectively switching a plurality of supply voltages for testing a plurality of withstand voltage characteristic items. do.

The withstand voltage characteristic test apparatus of the present invention for implementing such a method includes a power supply means including a plurality of power supplies for supplying a required supply voltage to each electrode of a CRT to be tested, and each power supply of the power supply means is selectively selected to each electrode. Measurement means for measuring a change in the supply voltage and the voltage and / or current of each electrode of the CRT when the switching means connected to the circuit board, the control means for controlling the selective connection of the switching means, and the power supply of the power supply means is selectively applied. Means are provided.

According to one preferred feature of the present invention, there is provided a protection means between the low voltage side electrode of the CRT and the switching means when it is excessively applied.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the device of the present invention. Other detailed features of the method of the present invention will be clearly understood from the following device description.

In FIG. 2, the cathode ray tube is provided with an anode A2, G1 to G3 electrodes G1 to G3, a cathode K and a heater H. Although the G4 electrode is not separately illustrated, the G4 electrode is connected to the anode A2 through the internal conductive film, and thus becomes an equipotential with the anode A2. Each electrode A2, G1 to G3, K, H has a corresponding power supply Ef, Ek, EC2, EC3, Eb of the power supply means 2 through a plurality of switches SW1 to SW6 that are switching means 1. Is selectively connected. Ef is the heater voltage, Ek is the cathode cut-off voltage, EC2 and EC3 are G2 and G3 voltages, Eb is the anode voltage, and G2 and G3 voltages (G2, G3) and anode voltage (Eb Are each composed of variable voltages.

In the meantime, each switch SW1 to SW6 of the switching means 1 is controlled by the control means CTR. Preferably, the control means CTR is constituted by a programmable logic controller (PLC) or a microprocessor. As shown in Fig. 1, the respective switches SW1 to SW6 are controlled.

The meters P1 to P4 of the measuring means 3 for measuring the supply voltage and / or the measurement current are connected to the second switch SW2 and the fourth to sixth switches SW4 to SW6. Preferably each meter (P1 ~ P4) is composed of a digital panel meter (DPM).

On the other hand, spark caps SG1 to SG3 are connected between the low voltage side of the CRT and the power supply as protection means 4 against high voltage application. These spark gaps SG1 to SG3 protect the test apparatus by bypassing the high voltage applied by the high voltage leakage between the electrodes to the ground side by the spark discharge. The remaining resistors R1 to R5 are protection resistors or load resistors to assist the bypass of the spark gaps SG1 to SG3.

Operation of the test apparatus of the present invention configured as described above is shown in Table 1, for example.

TABLE 1

The control means CTR performs the operation of controlling each switch SW1 to SW6 of the switching means 1 so as to be connected as shown in Table 1 above, so that each inspection item is sequentially audited. That is, although not shown separately, if six test mode selection switches corresponding to each row of <Table 1> are installed, for example, and the test instructor selects one mode selection switch, the control means CTR performs the row. The switches SW1 to SW6 corresponding to each other are connected.

The operation of the apparatus of the present invention will be described by taking the inspection of the G2 SE inspection and the FE inspection items in the first and fifth rows of Table 1 as an example. In the SE test, the neck light emission NG and the electrode leakage GL may be detected together.

First, when SE inspection of the G2 electrode G2 is selected, the switches SW1 to SW6 are connected as shown in the first row of Table 1, whereby the heater H and the cathode K, and the G1 and G2 electrodes G1 are connected. , G2) is grounded and a "0" potential is applied. At this time, the anode voltage (Eb) is fixed at the maximum rated voltage and the G3 voltage (EC3) is gradually increased from 0 V. When the G3 voltage (EC3) at the start of light emission on the screen is measured by the meter (P2), The voltage becomes the SE generation voltage of the G3 electrode G3. In this case, the neck light emission NG and the electrode leakage GL may be identified by visual inspection at the same time or separately.

On the other hand, when the FE inspection mode of the G2 electrode G2 is selected, the switches SW1 to SW6 are connected to the fifth row of <Table 1>. That is, the heater H is grounded, and the cathode K and the G1 and G2 electrodes G1 and G2 are commonly grounded with respect to the first meter P. At this time, the anode (Eb) is fixed to the maximum rated voltage and gradually increases the voltage G3 (EC3) to observe the increase of the current of the first meter (P1). At this time, the G3 voltage EC3 at the instant when the current value measured by the first meter P1 becomes larger than the prescribed value is defined as the FE generation voltage of the G2 electrode G2.

As described above, according to the present invention, it is possible to quickly and accurately grasp not only qualitatively but also quantitatively the test of the withstand voltage characteristic which has not been possible in the past. Accordingly, it is possible to fundamentally grasp the cause of the withstand voltage characteristic without destroying the vacuum of the CRT and to take appropriate countermeasures. As such, the present invention has a great effect on improving the quality of the CRT, in particular, the Claw-Crown tube.

Claims (3)

A method of testing a breakdown voltage characteristic by supplying a test voltage to a CRT, wherein the plurality of breakdown voltage characteristics are sequentially supplied by selectively switching a plurality of supply voltages for testing a plurality of breakdown voltage characteristics and supplying the test voltage to the CRT. Test method for withstand voltage characteristics of CRTs, characterized in that the test. An apparatus for testing a withstand voltage characteristic by supplying a test voltage to a cathode ray tube, the apparatus comprising: a power supply means including a plurality of power sources for testing a plurality of withstand voltage characteristics, and selectively connecting the respective power supplies of the power supply means to the cathode ray tube; Measuring the change in the supply voltage and the voltage and / or current of the CRT when the power supply of the power supply means is selectively supplied to the CRT. The withstand voltage characteristic test apparatus of a CRT, characterized in that it comprises a measuring means. 3. The apparatus of claim 2, wherein protection means for bypassing excessive high pressure is provided between the low voltage side electrode of the CRT and the power supply means.