JPH07115028A - Bias circuit device for cathode ray tube - Google Patents

Abstract

PURPOSE:To make it possible to adjust static focus voltage stably. CONSTITUTION:In a bias circuit device 1, a variable resistance circuit for static focus voltage composed of a resistor 1a, a variable resistor 1b and a resistor 1f, and a variable resistance circuit for dynamic focus voltage composed of a resistor 1a, a variable resistor 1d and a resistor 1f are connected to a high voltage through the medium of a terminal 1h. Besides, a variable resistance circuit for screen voltage composed of a resistor 1n and a variable resistor 1g is separated from variable resistance circuits for static focus voltage and dynamic focus voltage, and is connected to the high voltage through the medium of a terminal 1m. Voltage fluctuations by the adjustment of the static focus voltage does not exert influence on the screen voltage directly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube bias circuit device for supplying a focus voltage and a screen voltage to a cathode ray tube.

[0002]

2. Description of the Related Art In recent years, television receivers using a cathode ray tube having a large size and a high precision screen have become popular. A high voltage applied to this type of cathode ray tube, in particular, a high stability is required for the focus and screen voltages, and in order to improve focusing in the peripheral portion of the screen,
Dynamic focus tends to be required to superimpose a parabola voltage synchronized with the vertical deflection signal and the horizontal deflection signal.

Although there is the prior art disclosed in Japanese Utility Model Laid-Open No. 3-70467, a conventional cathode ray tube bias circuit device intended to be improved by the present invention will be described with reference to FIG. In the figure, reference numeral 1 is a variable resistor unit for supplying a focus voltage and a screen voltage to the cathode ray tube 3 which is connected to a flyback transformer 2 which generates a high voltage to be supplied to the cathode ray tube. Terminal 1h connected to the output of the secondary high-voltage winding,
Terminal 1i connected to the dynamic focus of the cathode ray tube 3 and terminal 1 connected to the static focus electrode
j, and a terminal 1k connected to the screen electrode, and a terminal 1L connected to the ground or the DC low voltage portion,
Resistors 1a and 1 for dividing the high voltage are provided inside thereof.
f, a variable resistor for static focus voltage 1b for adjusting the voltage, a variable resistor for dynamic focus voltage 1d, and a variable resistor for screen voltage 1g.
And protection resistors 1c and 1e. Reference numeral 4 is a capacitor for applying a combined parabolic voltage obtained by combining parabolic voltages output from the horizontal deflection circuit and the vertical deflection circuit to the output of the terminal 1j, and 5 is an influence of the parabolic voltage applied to the terminal 1j. This is a capacitor for smoothing the ripple voltage generated at the terminal 1i.

The operation of the above configuration will be described. The high voltage pulse generated in the high voltage windings 2a to 2f is rectified by a plurality of diodes, applied to the anode of the cathode ray tube 3 and applied to the terminal 1h of the variable resistor unit 1. This high voltage is divided by the resistor 1a, the parallel connection of the variable resistor 1b and the variable resistor 1d, and the series connection of the resistor 1f and the variable resistor 1g, and the output of the variable resistor 1b is output via the terminal 1i. The output of the variable resistor 1d is applied to the dynamic focus electrode via the terminal 1j, and the output of the variable resistor 1g is applied to the screen electrode of the cathode ray tube 3. The resistors 1c and 1
e is a protective resistance for preventing the variable resistors 1b, 1d and 1g from being destroyed when the static electrode and the dynamic focus electrode are erroneously short-circuited to a low potential. Further, a parabola voltage for correcting the focus voltage in the peripheral portion of the screen of the cathode ray tube 3 is input to the dynamic focus electrode via the capacitor 4, and is superimposed on the output voltage of the terminal 1j to generate a predetermined dynamic focus voltage. To be done. On the other hand, the voltage supplied to the static focus electrode requires a DC voltage that does not include a ripple component, but includes a ripple voltage component due to the influence of the parabola voltage input to the terminal 1j. To remove this ripple voltage, a capacitor 5 is connected between the terminal 1i and ground. This value is generally set to several hundred to one thousand pF. 6 is a static focus electrode, 7 is a dynamic focus electrode, and 8 is a screen electrode.

[0005]

In such a conventional cathode ray tube bias circuit device, when the variable resistor 1b for the static focus voltage is made variable, the capacitor 5 is
Due to the voltage drop due to the charging / discharging current, there is a problem that the divided voltage on the high potential side and the low potential side of the variable resistor 1b changes, and the screen voltage output to the terminal 1k excessively changes. When the screen voltage changes, the brightness on the screen of the cathode ray tube changes, and because the high voltage output current changes, the high voltage output voltage also fluctuates, making it difficult to adjust the static focus voltage on the screen. is there.

An object of the present invention is to solve the above problems and an object thereof is to provide a cathode ray tube bias circuit device capable of stably adjusting a static focus voltage.

[0007]

In order to achieve the above object, the present invention divides a high voltage output obtained by boosting and rectifying a flyback pulse and supplies it to a focus electrode and a screen electrode of a cathode ray tube. In a bias circuit device, a variable resistance circuit for static focus voltage that supplies a voltage to a static focus electrode of a cathode ray tube, a variable resistance circuit for a dynamic focus voltage that supplies a voltage to a dynamic focus electrode, and a screen that supplies a voltage to a screen electrode. A variable resistance circuit for voltage, the variable resistance circuit for screen voltage is connected to both ends of the high voltage output, and is separated from the variable resistance circuit for static focus voltage and the variable resistance circuit for dynamic focus voltage to obtain a high voltage. With a cathode ray tube bias circuit device connected to That.

[0008]

According to the present invention, in the above structure, the screen voltage variable resistance circuit is connected to a high voltage independently of the static focus variable resistance circuit and the dynamic focus variable resistance circuit, and is generated by adjusting the static focus voltage. Voltage fluctuations and high voltage fluctuations do not occur.

[0009]

【Example】

(Embodiment 1) An embodiment of the cathode ray tube bias circuit device of the present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a circuit diagram showing the configuration of this embodiment. The same components as those of the conventional example shown in FIG. 2 are assigned the same reference numerals and detailed explanations thereof will be omitted. The present invention is different from the conventional example in that the variable resistor 1g for the screen voltage is separated from the other variable resistors, connected in series with the resistor 1n, and directly connected to a high voltage via the terminal 1m.

To explain the operation in the above configuration, the variable resistor 1b supplies the focus voltage to the static focus electrode and the variable resistor 1d supplies the focus voltage to the dynamic focus electrode by dividing the high voltage. Further, the parabolic voltage is applied to the dynamic focus electrode via the capacitor 4. In this embodiment, the screen voltage is supplied with a voltage divided by the resistor 1n and the variable resistor 1g, and is separated from the circuits of the static focus variable resistor 1b and the dynamic focus variable resistor 1d. Even if the capacitor 5 is excessively charged and discharged when the static focus voltage is adjusted by the resistor 1b, the effect thereof does not directly appear in the variable resistor 1g, so the screen voltage is stable, and therefore, The focus voltage can be adjusted stably.

As described above, according to this embodiment, the variable resistor 1g for the screen voltage is not connected in series with the variable resistor 1b for the static focus voltage and the variable resistor 1d for the dynamic focus voltage. By separately providing a high voltage, the screen voltage is stable even if the static focus voltage is adjusted, and thus stable focus adjustment is possible.

[0012]

As is apparent from the above description, the present invention is a bias circuit device for dividing a high voltage output obtained by boosting and rectifying a flyback pulse and supplying the divided voltage to a focus electrode and a screen electrode of a cathode ray tube. In, a variable resistance circuit for static focus voltage that supplies voltage to the static focus electrode of the cathode ray tube, a variable resistance circuit for dynamic focus voltage that supplies voltage to the dynamic focus electrode, and a variable voltage for screen voltage that supplies voltage to the screen electrode A variable resistance circuit for the screen voltage is connected to both ends of the high voltage output, and is connected to a high voltage separately from the variable resistance circuit for the static focus voltage and the variable resistance circuit for the dynamic focus voltage. By this, the focus voltage resistance circuit Stable screen voltage is not affected by can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of a cathode ray tube bias circuit device of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a conventional cathode ray tube bias circuit device.

[Explanation of symbols]

1 Bias Circuit Device 1a, 1f Resistor (Static Focus Voltage Variable Resistor Circuit and Dynamic Focus Voltage Variable Resistor Circuit) 1b Variable Resistor (Static Focus Voltage Variable Resistor Circuit) 1d Variable Resistor (Dynamic Focus Voltage Variable Resistor Circuit) 1h Resistance (variable resistance circuit for screen voltage) 1g Variable resistance (variable resistance circuit for screen voltage) 3 Cathode ray tube 6 Static focus electrode 7 Dynamic focus electrode 8 Screen electrode

Claims (1)

[Claims] 1. A bias circuit device for dividing a high voltage output obtained by boosting and rectifying a flyback pulse and supplying it to a focus electrode and a screen electrode of a cathode ray tube, and supplying a voltage to a static focus electrode of the cathode ray tube. A variable resistance circuit for a static focus voltage, a variable resistance circuit for a dynamic focus voltage that supplies a voltage to a dynamic focus electrode, and a variable resistance circuit for a screen voltage that supplies a voltage to a screen electrode. Is connected to both ends of the high voltage output, and is separated from the variable resistance circuit for the static focus voltage and the variable resistance circuit for the dynamic focus voltage to be connected to a high voltage cathode ray tube bias circuit device.