KR20020083006A - Electron gun for cathode ray tube - Google Patents

Abstract

PURPOSE: An electron gun for a cathode ray tube is provided to prevent a variance of characteristic of a triode portion by a variance of voltage in a G3 electrode by installing a shielding electrode between a G2 electrode and the G3 electrode and maintaining constantly the voltage applied to the shielding electrode. CONSTITUTION: A cathode(10) is used for emitting thermal electron. A G1 electrode(20) and a G2 electrode(30) are used for controlling the thermal electron emitted from the cathode(10) and forming electron beams. A G3 electrode(40) and a G4 electrode(50) are used for focusing and accelerating the electron beams. The electron beams reach a screen(80) through a shadow mask(70). A shielding electrode(60) is located between the G2 electrode(30) and the G3 electrode(40). The shielding electrode(60) performs a shielding function in order not to transfer a variance of voltage applied to the G3 electrode(40) to the cathode(10), the G1 electrode(20), and the G2 electrode(30). A voltage supply portion supplies the voltage to the G1 electrode(20), the G2 electrode(30), the G3 electrode(40), the G4 electrode(50), and the shielding electrode(60).

Description

Electron gun for cathode ray tube {ELECTRON GUN FOR CATHODE RAY TUBE}

The present invention relates to an electron gun for a cathode ray tube, and more particularly, to an electron gun for a cathode ray tube that prevents a characteristic change of a triode portion due to a voltage change of a third grid electrode.

In general, an electron gun used for a cathode ray tube is a triode portion including a cathode, a first grid electrode (hereinafter referred to as G1 electrode), a second grid electrode (hereinafter referred to as G2 electrode), and a third grid electrode (hereinafter referred to as G3 electrode). And a fourth grid electrode (hereinafter referred to as G4 electrode), and when the hot electrons are emitted from the cathode conducting heat from the heated heater, the electrons are focused and diverted by the potential difference applied to each electrode. The phosphor film reaches the screen and emits phosphor.

When the electrons emitted from the electron gun cathode are focused in the main lens region formed by the G3 electrode to which several kV is applied and the G4 electrode to which 20 kV to 30 kV is applied, the voltage of the G3 electrode is considerably high pressure compared to the voltage applied to the triode. As the G3 electrode voltage changes, the electric field distribution of the triode portion changes, affecting the amount of emitted electrons of the cathode. That is, as the G3 voltage increases, the amount of current emitted from the cathode increases, and when the G3 voltage decreases, the amount of current decreases. The influence of the change of the voltage of the G3 electrode does not significantly affect the brightness and chromaticity problems of the conventional cathode ray tube.

However, in the case of a cathode ray tube in which a plurality of electron guns are inserted, the luminance and chromaticity difference of each screen should be adjusted for all driving voltages.

In the manufacturing process of a typical cathode ray tube, the setting of the focus voltage is located in the last process. The dispersion of the focus voltage setting is about 1 kV, and the potential distribution of the triode portion due to this dispersion is changed, and the color between the partial screens is completely changed due to the change in current. As a result, a cathode ray tube into which a plurality of electron guns are inserted has a problem in that image quality is very poor. In addition, when the same focus voltage is applied as a whole, the focus is not focused for each partial screen, which also adversely affects the image quality.

Accordingly, an object of the present invention is to provide a cathode ray tube electron gun which prevents a change in the characteristics of a triode portion due to a change in G3 voltage.

1 is a view schematically showing an electron gun for a cathode ray tube according to an embodiment of the present invention.

2 is a block diagram of a voltage supply unit in an electron gun for a cathode ray tube according to a first embodiment of the present invention.

3 is a block diagram of a voltage supply unit in a cathode ray tube electron gun according to a second embodiment of the present invention.

A feature of the present invention for achieving the above object is to provide a shielding electrode between the G2 electrode and the G3 electrode so that the effect of the voltage change applied to the G3 electrode does not reach the triode portion, the voltage applied to the shielding electrode is constant To keep it.

According to the above features, the present invention provides a negative electrode having an electron emission material; A first grid electrode and a second grid electrode configured to control the hot electrons emitted from the cathode to electron beam; A third grid electrode and a fourth grid electrode for focusing and accelerating the electron beam; A shielding electrode positioned between the second grid electrode and the third grid electrode, the shielding electrode shielding the change of the voltage applied to the third grid electrode from being transferred to the cathode, the first grid electrode, and the second grid electrode; And a voltage supply unit supplying a voltage to the second grid electrode, the third grid electrode, the fourth grid electrode 50, and the shielding electrode, wherein the voltage supply unit supplies a constant voltage to the shielding electrode. do.

The voltage supply unit receives a horizontal driving signal, a horizontal output unit for amplifying the signal and generating a sawtooth current; A flyback transformer receiving a current output from the horizontal output unit to the primary coil to induce a high voltage pulse to the secondary coil; And a high voltage output unit configured to receive a high voltage pulse induced in the secondary coil of the flyback transformer and generate respective voltages supplied to the second grid electrode, the third grid electrode, the fourth grid electrode, and the shielding electrode.

The high voltage output unit divides the voltage induced by the secondary coil of the flyback transformer into a predetermined number of resistors, supplies a voltage distributed to the first resistor side, which is the highest voltage, to a fourth grid electrode, and supplies the voltage to the first resistor. Supplying the shielding electrode with a second highest voltage that is a voltage distributed to the second resistor side to be connected, and removing the third highest voltage that is a voltage distributed to the third resistor side, which is a variable resistor connected to the second resistor side. And supplying a fourth grid voltage to the second grid electrode, the fourth grid electrode being a voltage distributed to the fourth resistor side, which is a variable resistor connected to the third resistor side.

Here, the second resistor may be supplied with a fixed voltage to the shielding electrode by using a fixed resistor, and the fixed resistor is supplied to the shielding electrode by fixing to a resistance value that provides an optimal focus characteristic of the electron gun using a variable resistor. You may also do it.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing an electron gun for a cathode ray tube according to an embodiment of the present invention.

As shown in FIG. 1, an electron gun for a cathode ray tube according to an embodiment of the present invention includes: a cathode 10 emitting hot electrons; A G1 electrode 20 and a G2 electrode 30 which control the hot electrons emitted from the cathode 10 to form an electron beam; G3 electrode 40 and G4 electrode 50 for focusing and accelerating the electron beam to impinge on screen 80 through shadow mask 70; A shielding electrode positioned between the G2 electrode 30 and the G3 electrode 40 and shielding the change of the voltage applied to the G3 electrode 40 from being transmitted to the cathode, the G1 electrode 20, and the G2 electrode 30. 60; And a voltage supply unit 90 supplying a voltage to the G1 electrode 20, the G2 electrode 30, the G3 electrode 40, the G4 electrode 50, and the shielding electrode 60.

The cathode 10 is heated by a built-in heater to emit hot electrons, and the potential of the G2 electrode 30 is adjusted according to the screen signal while the potential of the cathode 10 and the potential of the G1 electrode 20 are fixed. Control the density.

The electron whose current density is controlled in this way is prefocused in the prefocus lens formed between the G2 electrode 20 and the G3 electrode 30, and the main focus lens formed between the G3 electrode 30 and the G4 electrode 40. Final focusing and acceleration are directed to the shadow mask 70 and the screen 80.

A shielding electrode 60 is positioned between the G2 electrode 30 and the G3 electrode 40, and a constant voltage is applied to the shielding electrode 60.

The voltage applied to the shielding electrode 60 is determined by a manufacturing standard in consideration of aberration and collection speed, and specific gamma characteristics can be obtained by changing the voltages of the triode portion of the electron gun under the determined voltage.

In addition, after setting a specific voltage in the triode portion, just focus is set by changing the G3 focus voltage.

On the other hand, the voltage applied to the G3 electrode is about 5kV ~ 9kV, which is supplied from the voltage supply unit 90.

FIG. 2 is a block diagram of the voltage supply unit 90 in the cathode ray tube electron gun according to the first embodiment of the present invention.

As shown in FIG. 2, the voltage supply unit 90 of the cathode ray tube electron gun according to the first embodiment of the present invention includes a horizontal output unit 910, a flyback transformer 920 (hereinafter referred to as FBT), and a high voltage output unit 930. )

The horizontal output unit 910 receives the horizontal driving signal, amplifies the signal, and generates a sawtooth current.

At this time, the output voltage of the horizontal output unit 910 is induced in the primary coil L1 of the FBT 920, and the high voltage is applied in the secondary coils L2, L3, L4, and L5 of the FBT 920 according to the turns ratio of the coil. The pulse is induced.

As such, the high voltage pulse induced in the secondary coil of the FBT 920 is rectified by the high voltage output unit 930 to generate the G2 voltage, the G3 voltage, the G4 voltage, and the ABL (Automatic Brightness Limit) voltage.

The voltage supply unit 90 having such a structure will be described in more detail.

First, the horizontal output unit 910 has a gate terminal connected to a horizontal drive signal, a collector terminal connected to one terminal of the primary coil L1 of the FBT 920, and an emitter terminal grounded transistor Q1. , A rectifier diode (D) having a negative terminal connected to the collector terminal of the transistor (Q1) and a positive terminal grounded, a first capacitor (C1) connected between the transistor (Q1) and ground, and a series between the transistor (Q1) and ground. A horizontal deflection coil L and a second capacitor C2 are connected.

The horizontal output unit 910 receives the horizontal driving signal and amplifies the signal by the transistor Q1, and the amplified driving current generates the sawtooth current by the horizontal deflection coil L, and the second capacitor C2. ) To linearly correct the distorted signal. At this time, the rectifier diode D and the first capacitor C1 perform rectification and stabilization operations of the signal.

The output of the horizontal output unit 910 is connected to one terminal of the primary coil L1 of the FBT 920, and the other terminal receives the maximum voltage value of the horizontal output and the flyback pulse output from the horizontal output unit 910. A B + voltage is supplied to keep it constant.

When the output of the horizontal output unit 910 and the B + voltage are supplied to the primary coil L1, the FBT 920 induces a high voltage pulse to the secondary coils L2 to L5. The structure and voltage limits of the FBT 920 may be variously made according to a user's request.

The high voltage output unit 930 may include a G4 voltage generator 9310, a shield voltage generator 9320, a G3 voltage generator 9330, a G2 voltage generator 9340, an ABL voltage generator 9350, and a connection unit ( 9360).

The G4 voltage generator 9310 may include a first rectifying diode D1 and a cathode terminal of the first rectifying diode D1 having a positive terminal connected to the highest voltage terminal of the second coil L2 of the secondary side of the FBT 920. A capacitor CT connected between the ground lines and a high voltage generating resistor RH having one terminal connected to the negative terminal of the first rectifying diode D1 and connected to the negative terminal of the first rectifying diode D1. The G4 voltage is supplied to the G4 electrode 50.

The shielding voltage generator 9320 includes a resistor (RS) having one terminal connected to the other terminal of the resistor for high voltage generation (RH), and the shielding voltage through a contact between the resistor for high voltage (RH) and the resistor (RS). This shielding electrode 60 is supplied. At this time, the shielding voltage supplied to the shielding electrode 60 becomes a fixed voltage.

The G3 voltage generator 9330 is composed of a first variable resistor VR1 having one terminal connected to the other terminal of the resistor RS, and the G3 electrode 40 according to the resistance value adjustment of the first variable resistor VR1. The voltage supplied to is determined. Therefore, the voltage supplied to the G3 electrode 40 can be varied, and such a change in voltage is blocked by the shielding electrode 60 to which a fixed voltage is supplied, so that the side of the triode tube according to the voltage change of the G3 electrode 40 is changed. Property change is prevented.

The G2 voltage generator 9340 is configured of a second variable resistor VR2 connected to one terminal of the other terminal of the first variable resistor VR1 and the other terminal of which is grounded, and the resistance value of the second variable resistor VR2. As a result, the voltage supplied to the G2 electrode 30 is determined.

The ABL voltage generator 937 includes a second rectifying diode D2 having a negative terminal connected in a reverse direction to a lowest voltage terminal of the fifth coil L5 of the secondary side of the FBT 920. A predetermined voltage to be supplied to ABL is generated at the positive terminal of D2).

The connection part 939 includes a third rectifying diode D3 and a third coil L3 having a negative terminal connected to a secondary side second coil L2 of the FBT 920 and a positive terminal connected to a third coil L3. The fourth rectifier diode D4 having a negative terminal connected to the fourth terminal L4, and a negative terminal connected to the fourth coil L3, and a positive terminal connected to the fifth coil L5. Consisting of a fifth rectifying diode D5.

3 is a block diagram of a voltage supply unit 90 in a cathode ray tube electron gun according to a second embodiment of the present invention.

As shown in FIG. 3, the voltage supply unit 90 of the cathode ray tube electron gun according to the second embodiment of the present invention is similar to the voltage supply unit 90 according to the first embodiment shown in FIG. 910 and the flyback transformer (920, hereinafter referred to as FBT) are the same, and the resistance RS of the shielding voltage generator 9320 supplied to the shielding electrode 60 of the high voltage output unit 930 is the second. In the shielding voltage generator 9370 according to the embodiment, only the difference is made of the variable resistor VRS.

In the first embodiment, the voltage supplied to the shielding electrode 60 is fixed and used by setting the resistance RS value to be a voltage derived from a manufacturing standard. In the second embodiment, the voltage supplied to the shielding electrode 60 is used. Is fixed by using a variable resistor (VRS) as a resistor value that provides optimal focus characteristics.

Although the present invention has been described with reference to the most practical and preferred embodiments, the present invention is not limited to the above disclosed embodiments, but also includes various modifications and equivalents within the scope of the following claims.

According to the present invention, by inserting the shielding electrode 60 between the G2 electrode 30 and the G3 electrode 40, and supplying a constant voltage to the shielding electrode 60, according to the voltage change of the G3 electrode 40 The potential distribution of the triode can be prevented. Furthermore, when a plurality of electron guns are inserted to correct the luminance and chromaticity of the partial screen by adjusting the voltage of the triode, the influence of the G3 electrode 40 can be completely eliminated. .

Claims (4)

A cathode having an electron emitting material; A first grid electrode and a second grid electrode configured to control the hot electrons emitted from the cathode to electron beam; A third grid electrode and a fourth grid electrode for focusing and accelerating the electron beam; A shielding electrode positioned between the second grid electrode and the third grid electrode, the shielding electrode shielding the change of the voltage applied to the third grid electrode from being transferred to the cathode, the first grid electrode, and the second grid electrode; And Voltage supply unit for supplying voltage to the second grid electrode, third grid electrode, fourth grid electrode 50, and shielding electrode Including, The voltage supply unit supplies a constant voltage to the shielding electrode Electron gun for cathode ray tube. The method of claim 1, The voltage supply unit A horizontal output unit configured to receive a horizontal drive signal, amplify the signal, and generate a sawtooth current; A flyback transformer receiving a current output from the horizontal output unit to the primary coil to induce a high voltage pulse to the secondary coil; And A high voltage output unit configured to receive high voltage pulses induced in the secondary coil of the flyback transformer to generate respective voltages supplied to the second grid electrode, the third grid electrode, the fourth grid electrode, and the shielding electrode. Electron gun for cathode ray tube comprising a. The method of claim 2, The high voltage output unit Divide the voltage induced in the secondary coil of the flyback transformer by a predetermined number of resistors, Supplying a voltage distributed to the first resistor side, which is the highest voltage, to the fourth grid electrode, Supplying a second highest voltage to the shielding electrode, the voltage being distributed to the second resistor side connected to the first resistor, Supplying a third highest voltage, which is a voltage distributed to a third resistor side, which is a variable resistor connected to the second resistor side, to a third grid electrode; Supplying a fourth grid voltage to the second grid electrode, the fourth highest voltage being divided to the fourth resistor side, which is a variable resistor connected to the third resistor side. Electron gun for cathode ray tube, characterized in that. The method of claim 2, The high voltage output unit Divide the voltage induced in the secondary coil of the flyback transformer by a predetermined number of resistors, Supplying a voltage distributed to the first resistor side, which is the highest voltage, to the fourth grid electrode, Supplying a second highest voltage to the shielding electrode, the voltage being connected to the first resistor and distributed to the variable resistor side; Supplying a third highest voltage, which is a voltage distributed to a third resistor side, which is a variable resistor connected to the second resistor side, to a third grid electrode; Supplying a fourth grid voltage to the second grid electrode, the fourth highest voltage being divided to the fourth resistor side, which is a variable resistor connected to the third resistor side. Electron gun for cathode ray tube, characterized in that.