JPH08111176A - Knocking method of cathode ray tube - Google Patents

Abstract

(57) [Summary] [Objective] An object of the present invention is to provide a method of knocking a cathode ray tube capable of preventing dielectric breakdown of built-in split resistors, electrode parts, etc. without impairing the effect of external resistors during the knocking process. To do. [Configuration] A knocking voltage is applied to the ground terminal of the built-in dividing resistor R for supplying the convergence voltage built in the neck portion of the electron gun through the parallel circuit of the external resistor r and the capacitor C, and is equivalent. The stray capacitance C1 of the electron gun and the stray capacitance C2 due to the wiring, which are connected in parallel to the internal dividing resistor R and the external resistor r, respectively, and the impedance between the internal dividing resistor R and the external resistor r. The capacitor C is used for matching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of knocking a cathode ray tube for preventing the dielectric breakdown of the built-in resistor in an electron gun knocking process of a cathode ray tube having a built-in resistor.

[0002]

2. Description of the Related Art Among color cathode ray tubes, an electron gun arranged at a neck portion of a color cathode ray tube having an electron gun having a built-in dividing resistor is provided with three cathodes corresponding to red, green and blue. Has been. FIG. 3 is a color cathode ray tube (hereinafter, referred to as CRT) for explaining a conventional knocking method of the cathode ray tube.
Is a schematic explanatory view mainly showing a portion of an electron gun. In FIG. 3, inside the neck portion 1a of the CRT 1,
First common to the above three cathodes (not shown)
The grid G1 to the fifth grid G5 are sequentially arranged,
Electrostatic convergence means (also not shown) is arranged at the subsequent stage of the fifth grid G5. Although not shown, the electrostatic convergence means includes a pair of inner deflection electrodes and a pair of outer deflection electrodes facing each other.

The third grid G3 and the fifth grid G5 are electrically connected, an anode voltage is applied from the anode button 2 through the internal conductive film coated on the inner surface of the CRT1, and the fourth grid G4 is By applying a relatively low voltage, the third grid G3 to the fifth grid G5
It constitutes a unipotential type main electron lens. Also, the inner deflection electrode is electrically and mechanically coupled to the fifth grid G5 to apply an anode voltage, and the outer deflection electrode is applied with a convergence voltage lower than the anode voltage via the built-in division resistor R. I have to.

That is, the built-in divided resistor R has a resistance path formed on one surface of a predetermined insulating substrate, and has a first terminal and a second terminal formed at both ends of the resistance path, and at the same time, an arbitrary resistance path is formed. A third terminal is formed at an intermediate position,
In addition, they are arranged on the side surfaces of the first grid G1 to the fifth grid G5. Of these, the first terminal (downward in FIG. 3)
Connected to a ground potential stem pin (not shown),
By connecting the second terminal (upper part in FIG. 3) to the fifth grid of the anode voltage and connecting the third terminal to the outer deflection electrode of the electrostatic convergence means, the convergence voltage is passed through the built-in dividing resistor R. Is applied. With such a connection relationship, the potential difference between the inner deflection electrode and the outer deflection electrode is usually 1.5 to
It is designed to have a potential difference of about 2.0 KV. That is, the built-in dividing resistor R is a built-in dividing resistor for supplying the convergence voltage.

By the way, in the manufacturing process of a CRT equipped with an electron gun having a built-in dividing resistor R, as a measure for preventing discharge after exhausting the CRT, the electrode section of the electron gun usually has 50 to 50% or less.
A knocking step of applying a knocking voltage of about 55 KV is introduced. When a high voltage is applied in the knocking step, the inner wall of the neck portion 1a facing the third grid G3 and the fifth grid G5 on the high voltage side of the electron gun and the surface of the built-in dividing resistor R are charged. Built-in dividing resistor R
Is normally covered with an insulator, and the surface potential of the built-in divided resistor R in the vicinity of the third grid G3 increases due to the surface of the insulator being charged, which exceeds the withstand voltage of the insulator. At this time, this insulator is dielectrically destroyed, which in turn destroys the built-in dividing resistor R itself.

Therefore, regarding the implementation of this knocking step, the built-in dividing resistor R is prevented from being destroyed by Japanese Patent Application Laid-Open No. 63-138632 previously filed and published by the same applicant as the present invention. It is disclosed. In this publication, an external resistor r having a resistance value in the range of 1/5 to 1/30 of the resistance value of the built-in split resistor R is provided at the ground terminal of the built-in split resistor R built in the electron gun. Is connected as shown in FIG. 3 to raise the potential of the built-in divided resistor R facing the high voltage electrode of the electron gun, thereby preventing the dielectric breakdown of the built-in divided resistor R.

FIG. 4 is an equivalent circuit diagram when the knocking process of the color cathode ray tube having the built-in dividing resistor R is performed with the external resistor r attached, when the anode is grounded. A case where the anode is grounded will be described with reference to FIGS. 3 and 4. The low-voltage side electrode potential of the electron gun of FIG. 3 is shown as E1 in the equivalent circuit diagram of FIG. 4, the high-voltage side electrode potential is shown as E3 of FIG. 4, the ground terminal potential of the built-in dividing resistor R is E2, and the knocking voltage is HV. Further, as shown in FIG. 4, it is equivalent to the stray capacitance C1 of the electron gun being connected in parallel to the built-in dividing resistor R, and the stray capacitance C2 by wiring is connected in parallel to the external resistor r. Is equivalent to. As the knocking voltage HV, as shown in FIG. 5, a voltage obtained by switching a DC voltage or a DC voltage obtained by half-wave rectification is applied between the low voltage side electrode of the electron gun and the ground side of the built-in dividing resistor R. Alternately combine the type and the type using the pulse voltage as shown in FIG. 6 using the induction coil, or
Alternatively, each is used alone.

In FIG. 4, when discharging is performed between the low-voltage side electrode and the high-voltage side electrode of the electron gun, the knocking voltage to be applied is the electron gun low-voltage side electrode potential in an ideal case without the stray capacitances C1 and C2. The voltage changes from E1 to 0V, and the ground terminal potential E2 becomes as shown in the following expression (1). E2 = E1 × R / (R + r) (1) The applied voltage waveform of the knocking voltage shown in FIG. 7 is a low voltage of the electron gun with respect to the solid line waveform a. The applied voltage of the knocking voltage in the transient phenomenon at the time of discharge between the side electrode and the high voltage side electrode becomes like the waveform b of the broken line shown in FIG. 7, and as shown in the enlarged view of FIG. The voltage waveform a changes from the electron gun low-voltage side electrode potential E1 to 0 V, and the built-in dividing resistor R
The ground terminal potential E2 of is as shown by the solid line waveform b in FIG.

As described above, in the case of an ideal circuit without the stray capacitances C1 and C2, as is clear from the equation (1) and FIG. 8, it is proportional to the change of the electron gun low-voltage side electrode potential E1. Since the ground terminal potential E2 also changes like the waveform b of the solid line in FIG. 8, the voltage between E1 and E2 (= ΔEA) becomes as shown in the following equation (2), and becomes larger than when the knocking voltage is applied during the discharge. There is no such thing. ΔEA = (r × E1) / (R + r) ... (2)

[0010]

However, in reality, stray capacitances C1 and C2 exist, and the stray capacitance C
Nos. 1 and C2 cannot be ignored because the built-in dividing resistor R and the external resistor r are large. In the case of the above publication, by connecting the external resistor r to the ground terminal of the built-in split resistor R and applying a knocking voltage, the built-in split resistor R can be prevented from dielectric breakdown, but the external resistor is r is 1/5 to 1/3 of the resistance value of the internal dividing resistor R
It is set to 0, and due to the influence of the stray capacitances C1 and C2 of the cathode ray tube, a sharp change in the knocking applied voltage that occurs when a discharge is generated between the high-voltage side electrode and the low-voltage side electrode of the electron gun in the knocking process, , Due to a transient phenomenon, the potential of the ground terminal of the built-in division resistor R and the lower side electrode of the electron gun,
For example, a potential difference is generated between the first grid G1 and the second grid G2 shown in FIG. 3, which causes dielectric breakdown near the ground terminal portion of the built-in split resistor R, an insulator near the ground terminal portion,
That is, there is a problem that dielectric breakdown of the protective glass occurs.

In other words, when the stray capacitances C1 and C2 exist, the ground terminal potential E2 at the time of discharging between the low voltage side electrode and the high voltage + electrode of the electron gun causes the charge of the stray capacitance C1 to be Q1.
And the charge of the stray capacitance C2 is Q2, this charge Q
1 and Q2 are expressed by the following equations (3) and (4), respectively. Q1 = C1E2 ... (3) Q2 = C2 (E1-E2) ... (4) Since Q1 = Q2 is an excessive phenomenon at the time of this discharge, the relationship between the above equations (3) and (4) is as shown in the following equation (5). C1E2 = C2 (E1-E2) ... (5) Therefore, from this equation (5), E2 = (C2 * E1) / (C1 + C2) ... (6) Therefore, the potential difference ΔE between the ground terminal potential E2 of the built-in split resistor R and the electron gun low-voltage side electrode potential E1 is ΔE = E1-E2 = (C1 × E1) / (C1 + C2) ...・ It becomes (7). Here, stray capacitances C1 and C2 are C1 =
Considering the potential difference ΔE in the case of 10 pF and C2 = 10 pF, ΔE = (10 pF × E1) / (10 pF + 10 pF) = E1 / 2 ... ... (8), the potential difference ΔEA without stray capacitances C1 and C2
In comparison with FIG. 8, as shown by the white arrow c, the potential difference Δ between the ground terminal potential E2 and the electron gun low-voltage side electrode potential E1
E becomes large, resulting in a curved line d in FIG.

That is, the relation between the above equations (8) and (2) is ΔE = E1 / 2> ΔEA = (R + r) (9) , R = R / 5 to R / 30). Therefore, there is a problem that dielectric breakdown of the built-in split resistor near the ground terminal of the built-in split resistor or dielectric breakdown of the protective glass of the electrode of the ground terminal occurs. The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a built-in resistor and an external resistor by connecting a capacitor in parallel to an external resistor to a ground terminal during a knocking process. By matching impedance with stray capacitance, we provide a method of knocking cathode ray tubes that can prevent dielectric breakdown of built-in resistors, electrodes, and electrodes during the knocking process without impairing the effect of external resistors. Especially.

[0013]

A knocking voltage is applied to a ground terminal of a built-in resistor via a parallel circuit of an external resistor and a capacitor during a knocking process of an electron gun of a cathode ray tube having a built-in resistor. The impedances of the built-in resistor, the external resistor, and the stray capacitance are matched by the capacitor.

[0014]

In the knocking process of the cathode ray tube having the electron gun having the built-in resistor, the capacitance of the capacitor connected in parallel to the external resistor is equivalent to that of the built-in resistor and the external resistor. Impedance due to each connected stray capacitance is matched, even in the transient phenomenon during discharge between the low voltage side electrode and the high voltage side electrode of the electron gun,
Make the knocking voltage the same as the change in the ground terminal potential when there is no stray capacitance.

Therefore, the potential difference between the ground terminal potential of the built-in resistor and the electron gun low-voltage side electrode potential can be set to an appropriate value without impairing the effect of the external resistor.
It is possible to prevent damage to the built-in resistor and damage to the insulating layer such as the protective glass of the electrode.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an equivalent circuit diagram of a portion of an electron gun having a built-in dividing resistor applied to the knocking method of the cathode ray tube of the present invention. In FIG. 1, the same members used in the description of the conventional example shown in FIGS. 3 and 4 are designated by the same reference numerals. R in FIG. 1 is a built-in dividing resistor for convergence voltage supply, which is arranged in the electron gun at the neck portion of the color cathode ray tube (not shown), and is an example when it is used as a built-in resistor built in the electron gun. Is shown as. One end of the external resistor r is connected to the outside of the electron gun in series with the ground terminal side of the built-in split resistor R, and the knocking voltage HV is applied to the other end of the external resistor r. As for the knocking voltage HV, the high voltage side electrode potential E3 is applied to the high voltage side electrode of the electron gun.

The stray capacitance C1 of the electron gun is equivalently connected in parallel to the internal dividing resistor R, and similarly, the stray capacitance C2 by wiring is equivalently connected in parallel to the external resistor r. ing. The parts up to this point are the same as those of the conventional example according to the publication shown in FIG. A capacitor C is connected in parallel to the external resistor r, and this content C is a characteristic part of this embodiment. Capacitor C
Is the stray capacitance C1 of the electron gun that is equivalently parallel to the built-in divided resistor R and the external resistor r such that the resistance value ratio between the built-in divided resistor R and the external resistor r is reciprocal. This is for matching the capacitance ratio due to the stray capacitance C2 due to wiring that is equivalently parallel to. In FIG. 1, E1 is the low-voltage side electrode potential of the electron gun and E2 is the ground terminal potential, as in the case of FIG. Further, also in the case of the embodiment shown in FIG. 1, the case where the anode is grounded as the knocking voltage HV is illustrated.

Next, the knocking method of the cathode selection tube of the present invention will be described. In the knocking process in the manufacturing process of the color cathode ray tube having the electron gun having the built-in dividing resistor R, a knocking voltage HV is applied between the anode button of the color cathode ray tube and the electron gun low-voltage side terminal to lower the voltage of the electron gun. Knocking is performed by discharging between the side electrode and the high voltage side electrode. At the time of discharging in this knocking process, in order to reduce the potential difference ΔE between the electron gun low-voltage side electrode potential E1 and the ground terminal potential E2, the capacitance of the capacitor C connected in parallel to the external resistor r is It is selected so as to satisfy the relationship of the expression (10). C1 / (C1 + C2 + C) = r / (R + r) ... (10) In this equation (10), C1 is the stray capacitance of the electron gun,
C2 is the stray capacitance due to the wiring, C is the capacitance of the capacitor C connected in parallel to the external resistor r, r is the resistance value of the external resistor r, and R is the resistance value of the internal dividing resistor R. ,.

That is, as is apparent from the equation (10), the built-in divided resistor R and the external resistor r are arranged so that the resistance value ratio of the built-in divided resistor R and the external resistor r is the reciprocal number. The capacitance of the capacitor C is set to a capacitance value that matches the ratio of the stray capacitance C1 of the electron gun and the stray capacitance C2 of the wiring that are equivalently present in parallel.

In this way, the impedance of the capacitor C is matched with the impedance of the stray capacitance C1 of the electron gun and the stray capacitance C2 of the wiring, which are equivalently provided in parallel with the internal dividing resistor R and the external resistor r. As a result, even when the knocking voltage is transiently discharged, the change in the ground terminal potential E2 in the case where there is no stray capacitance C1 of the electron gun and the stray capacitance C2 due to the wiring in FIG. 8 can be made the same. Therefore, the potential difference ΔE between the electron gun low-voltage side electrode potential E1 and the ground terminal potential E2 can be obtained without impairing the effect that the external resistor r can reduce the potential difference between the internal divisional resistor R and its surface potential. The value can be set to an appropriate value, and the damage of the resistor of the built-in split resistor R and the destruction of the protective insulating layer can be prevented. Along with this, as shown by the curve a in FIG. 2, in the prior art, the occurrence rate of the breakdown of the insulating layer was generated substantially in proportion to the applied knocking voltage. As shown in the characteristic b of, the applied knocking voltage is 75 KV
It can be seen that the insulation layer is not destroyed up to the vicinity.

It is desirable that the capacitance of the capacitor C connected in parallel to the external resistor r satisfies the above equation (10), but C1 / (C1 + C2 + C) = L, r / (R + r) = K, a range of L = K / 3 to 3K, that is, a built-in dividing resistor R, an external resistor r, and stray capacitances C1 and C2.
In the range of ⅓ to 3 times the reference ratio, the same effect can be obtained in practical use.

Further, in the above embodiment, the case where the anode is grounded has been illustrated, but the present invention is not limited to this, and the same effect as that of the above embodiment can be obtained by grounding on the stem side. Furthermore, the same effect can be obtained not only with the uni-potential type electron gun, but also with the bi-potential type. In addition, the case where the built-in dividing resistor R for supplying the convergence voltage is used as the built-in resistor built in the electron gun has been described. However, the present invention is not limited to the built-in dividing resistor R and is for the focus voltage supply. The same effect can be obtained with a built-in resistor.

Accordingly, the present invention not only protects the built-in dividing resistor R from damage as described in the above embodiment, but also ground terminal potential E2 and electron gun low voltage electrode potential E1.
There is also a protective effect against a defect caused by the potential difference ΔE between them, such as a cathode and a heater.

[0024]

As is apparent from the above description, according to the present invention, the built-in resistor is connected through a parallel circuit of an external resistor and a capacitor during the knocking process of the electron gun of the cathode ray tube having the built-in resistor. A knocking voltage is applied to the ground terminal, and impedances of the built-in resistor, the external resistor, and the stray capacitance are matched by the capacitor. Therefore, the discharge between the low-voltage side electrode and the high-voltage side electrode due to the knocking voltage is performed without impairing the effect that the knocking voltage does not need to be reduced by reducing the potential difference between the internal resistor and the surface potential by the external resistor. At this time, it is possible to prevent damage and destruction of the resistor of the built-in resistor, its protective layer and the electrode part.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram of a part of a built-in dividing resistor built in an electron gun for explaining a knocking method of a cathode ray tube according to the present invention.

FIG. 2 is a characteristic diagram showing a rate of occurrence of dielectric breakdown due to a knocking voltage between a low voltage side electrode and a high voltage side electrode of an electron gun according to the present invention and a conventional example during discharge.

FIG. 3 is a schematic configuration explanatory view of a part of a built-in dividing resistor built in an electron gun for explaining a conventional knocking method of a cathode ray tube.

FIG. 4 is an equivalent circuit diagram for explaining a conventional method of knocking a cathode ray tube in the case where the anode of the built-in divided resistor portion built in the electron gun is grounded.

FIG. 5 is a waveform diagram of a knocking voltage obtained by switching a DC voltage for application to a conventional cathode ray tube knocking method.

FIG. 6 is a waveform diagram of a knocking voltage by a pulse voltage obtained by using an induction coil or the like for application to a conventional knocking method of a cathode ray tube.

FIG. 7 is an applied voltage waveform of a knocking voltage and a voltage waveform diagram at the time of discharging between the low voltage side electrode and the high voltage side electrode of the electron gun due to the knocking voltage for explaining the conventional knocking method of the cathode ray tube.

FIG. 8 is an applied voltage waveform and a ground terminal potential E2 at the time of discharge between the low voltage side electrode and the high voltage side electrode of the electron gun by the knocking voltage for explaining the conventional knocking method of the cathode ray tube.
FIG. 5 is an explanatory diagram of voltage waveforms with and without stray capacitance.

[Explanation of symbols]

 R Internal split resistor r External resistor C Capacitor HV Knocking voltage C1 Electron gun stray capacitance C2 Wiring stray capacitance E1 Electron gun low voltage side electrode potential E2 Earth terminal potential E3 Electron gun high voltage side potential

Claims (3)

[Claims] 1. A knocking voltage is applied to a ground terminal of the built-in resistor via a parallel circuit of an external resistor and a capacitor during a knocking process of an electron gun of a cathode ray tube having a built-in resistor, and the built-in resistor is built in. A method for knocking a cathode ray tube, wherein impedances of a resistor, the external resistor and a stray capacitance are matched by the capacitor. 2. The resistance value of the built-in resistor and the external resistor and the floating value are set by setting the ratio of the capacitance of the capacitor and the stray capacitance of the cathode ray tube to the ratio of the built-in resistor and the external resistor. The method of knocking a cathode ray tube according to claim 1, wherein impedances of capacitors are matched. 3. The method of knocking a cathode ray tube according to claim 2, wherein the capacitance of the capacitor is within a range of 1/3 to 3 times the basic ratio of the built-in resistor and the external resistor. .