JPS60167573A - Horizontal output circuit - Google Patents

Abstract

PURPOSE:To produce a distortion correcting voltage without lowering the level of the S-shaped correction capacitor voltage and to obtain the satisfactory distortion correcting effect even with a miniature TV having a small change of load current, by changing the base current of a distortion correcting transistor in response to the screen brightness. CONSTITUTION:The primary input current of a flyback transformer 10 flows through a distortion correcting transistor 18, and the voltage corresponding to said current is produced at an emitter resistance 21. When the screen brightness is high, the emitter voltage increases by the resistance 21. However the base current is reduced since the voltage is constant at a point B. Thus the storage time Ts of the transistor 18 is decreased to turn off the transistor quickly. If the time Ts of a horizontal output transistor 17 is set constant, a collector current is flowed into a correcting transistor 15 for a long period during which an output transistor is turned off. Thus a large quantity of voltage is produced to reduce the horizontal size. When the screen brightness is low, the voltage generated by the resistance 21 is reduced. While the base current of the transistor 18 increases to increase the Ts. Thus the charging period is reduced to the capacitor 15. This reduces the generated voltage and increases the horizontal size.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a horizontal output circuit, and particularly to a horizontal output circuit that corrects the bulge caused by a decrease in cathode ray tube island pressure when the inter-screen brightness becomes bright. The present invention relates to a distortion correction circuit suitable for.

[Background of the invention]

The conventional distortion correction circuit is shown in FIG. 1 except for the part inside the dotted line. The operation of the conventional circuit is described in Japanese Patent Application No. 58-3.
2845, so it will not be explained in detail here.

This method generates a voltage in the capacitor 15 according to the primary l...coil current of the flyback transformer 10.
When the screen distance is low, the primary inflow current increases and capacitor 1
5 increases, and the voltage of figure 8 correction capacitor 9 decreases by that amount. For this reason, the horizontal deflection current is small when it is bright.

Reduce the size and perform size correction. Here, in a small television reception area of 16 inches or less, when the screen-to-screen brightness changes,
The amount of change in the current flowing into the primary coil of the flyback transformer 1o is generally smaller than that of a large television receiver such as a 20-inch TV.

This can be easily understood from the fact that even though the CRT beam current changes are the same for large and small television receivers, the small size has a smaller high voltage background change due to lower high voltage.

Furthermore, in the case of a small size, the coating capacity of the cathode ray tube is smaller than in the case of a large size, and high pressure fluctuations due to changes in brightness are large. For this reason, the proportion of distortion is usually higher than that of large-sized ones.

In the above situation, if you try to make distortion correction effective using the conventional circuit, you have no choice but to make the capacitor 15 smaller.By making the capacitor smaller, even when the screen is dark,
The voltage generated in capacitor 15 increases, and 8
The pressure through the correction capacitor 9' becomes smaller. high pressure drop,
This results in a decrease of 1 in the horizontal deflection current, and even if the power supply voltage 11 of a 14-inch television receiver is 113V, the voltage of the capacitor 9 decreases to about 98V.

As the TV receiver becomes smaller, the above phenomenon becomes stronger and normal horizontal deflection operation becomes impossible.

Hateful.

[Purpose of the invention]

An object of the present invention is to generate a distortion correction voltage without reducing the figure-8 correction capacitor voltage and to provide a sufficient distortion correction effect even in a small television receiver with small load current changes. [Summary of the Invention] When the screen distance is low, the base current of the distortion correction transistor is reduced and the stray of this transistor is reduced. .

Reduce the time and turn off the horizontal output transistor earlier.

As a result, the collector current of the horizontal output transistor is
Charge the correction capacitor and increase the distortion correction voltage. Also, if the screen is dark, correct distortion.

The base current of the transistor is increased so that the Ts of this transistor and the horizontal output transistor are turned off almost simultaneously. This reduces the amount of light from the correction capacitor and lowers the voltage of the correction capacitor. 7! being moved. Transistor 7 has a large collector current, so
Driven by large base current, storage time (T
s) is usually as long as about 4.5 μs.

In addition, since the distortion correction transistor 18 allows only the primary coil current of the flyback transformer 10 to flow, a low base current is sufficient, and the Ts of 1 μs is 1° in the Shini61. In this circuit, the correction capacitor 15 is charged by the collector current l flow for 6.5 μs from the time when the distortion correction transistor is turned off until the horizontal output transistor is turned off.

FIG. 2 shows the collector voltage of the horizontal excitation transistor 41° of FIG. 1.

(2) indicates the base drive voltage of the distortion correction transistor 18.

In Figure 1, the flyback transformer primary inflow 'Tt
R flows through the transistor 8, causing the emitter resistor 21 to generate a voltage corresponding to the current.

Shown in Figure 2 ◎.

When the distance between the screens is low, the emitter voltage changes due to the resistor 21, as shown in Figure 1. ■Since the voltage is constant, ■-■ If the voltage is small, the base current decreases and becomes as shown in Figure 2 a. The transistor turns off as soon as +1+S shown in the figure is not shortened.

If Ts of the horizontal quadrant sister 7 is one foot, the collector current L will be low for a long period until this transistor is turned off.
The current flows into the correction capacitor 5 to generate 11. a large voltage. Reduce horizontal size.

When the screen is dark, the voltage generated by the resistor 21 is small, the distortion correction transistor pace current increases, and Ts increases.

The charging period for the correction capacitor 5 is reduced, and the generated voltage is small. Increase the horizontal size by 1°.

As described above, by changing the pace current of the distortion correction transistor 18, it is possible to suppress an increase in the correction voltage of the correction capacitor 5 and increase the distortion correction effect when the screen is dark.

〔Effect of the invention〕

According to the present invention, due to the inexpensive circuit configuration, it is possible to apply the present invention to even small-sized televisions.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a voltage shaping diagram of the % portion of FIG. 1. 1...Resistor 2...Capacitor 4...Horizontal excitation transistor 7...Resonance capacitor -1°8...
Horizontal DY 9...8 figure correction capacitor 10...Flyback transformer 11...
・Power supply voltage 12...High voltage rectifier diode 113...
... High voltage capacitor 14 ... Cathode ray tube equivalent resistance 15 ... Correction capacitor 17 ... Horizontal output transistor with damper diode 18 ... Distortion correction transistor 19 ... ...Horizontal excitation transformer 20...Base resistor 21...Resistor Figure 1 Figure 2

Claims (1)

[Claims] It includes a horizontal output transistor with a damper diode connected in parallel, a series circuit of a horizontal deflection yoke, a figure-8 correction/capacitor, and a parallel connection circuit with a resonant capacitor, and a flyback transformer primary side is connected to the high voltage side of the parallel connection circuit. A correction capacitor and a correction transistor are connected in parallel to each other through a coil to the positive electrode side of the power source and between the negative electrode side of this power source and the low voltage side of the parallel connection Wc circuit, and the correction transistor base and the horizontal output In a horizontal output circuit configured to apply W1 voltage of the same polarity to the transistor base and turn it on and off synchronously, in response to an inflow current from the positive electrode side of the power supply to the flypacked 1 lance primary coil,
A horizontal output circuit characterized in that the base current of the correction transistor is controlled.