JPH01264364A - Image size switching circuit - Google Patents

Abstract

PURPOSE:To correct the fluctuation of size due to the brightness of a picture by providing a circuit controllable for the S-correction voltage of a horizontal deflection circuit, detecting a voltage proportional to the increment/decrement of the S-correction voltage, and switching the size of a variable impedance element. CONSTITUTION:The DC voltage levels of the voltages at both ends of a capacitor 13 can be changed by driving a transistor 16 from a voltage terminal. Thereby, the horizontal size can be changed freely. For example, the voltages at both ends of the capacitor 13 are increased by reducing the resistance value of a resistor 17, and the S-correction voltage is decreased, thereby, the picture size in a horizontal direction can be reduced. Next, the voltages at both ends of the capacitor 13 are increased by reducing the picture size at the time of switching the vertical size. Therefore, the impedance of the variable impedance element can be increased when the voltages at both ends of the capacitor 13 are smoothened, and the fluctuation of a DC voltage is connected to the variable impedance element, and the voltages at both ends of the capacitor 13 increase. In such a way, a vertical feedback voltage is increased, then, the vertical size can be reduced. When the brightness of the picture is heightened, the picture size is changed so as to be increased, then, a charge quantity to a capacitor 9 can be increased. Therefore, the picture size can be reduced both in the vertical and horizontal directions based on the above principle of size switching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] 1. The present invention relates to a deflection circuit for a television receiver, and particularly to a size switching circuit suitable for varying the amount of information on a screen.

[Conventional technology]

The conventional technology has applied the circuits shown in FIGS. 3 and 4. 3 shows the horizontal size switching section, and FIG. 4 shows the vertical size switching section. By switching the switch 12 in FIG. 0, the relay 8 is turned off and the inductance L is connected in series to the horizontal deflection coil. Horizontal size becomes smaller. On the other hand, the vertical size switching section changes the vertical size stepwise by connecting or disconnecting a resistor in parallel to the vertical AC burst resistance by switching the switch 12'lk.

Items related to the present invention include those described in the TV Technology All Manufacturers Service Book, 1986, 9B1 special edition, Pd2.

[Problem to be solved by the invention]

The above-mentioned prior art is in the horizontal size switching section.

An inductance element and a relay are used, and a horizontal deflection current flows through each pixel, therefore.

In a TV receiver with a large screen and a large deflection angle, both the inductance element and the relay, which have a large horizontal deflection current, are large and the cost increases. Furthermore, in the prior art, the screen size is changed in stages, so it is not possible to set the screen size to an arbitrary size. Furthermore, in the conventional technology, there is no means to correct the fluctuation in screen size caused by fluctuations in high voltage due to fluctuations in screen brightness, and the 0 screen size changes due to fluctuations in brightness regardless of whether it is a standard screen or a small screen. There was a problem.

An object of the present invention is to change the size of one screen using inexpensive parts, change the size continuously, and correct size fluctuations due to the brightness of one screen.

[Means to solve the problem]

The above purpose is to provide a circuit that can control the figure-8 correction voltage of the horizontal deflection circuit, detect a voltage proportional to the increase or decrease in the figure-8 correction voltage, provide a variable impedance element, and connect it to the vertical feedback circuit. Yoshishi.

achieved.

[Effect]

The figure 8 correction voltage of the horizontal deflection circuit can be adjusted by detecting a voltage proportional to the S raw captured voltage fluctuation and applying a variable impedance element. , if connected to a vertical feedback circuit, the vertical size can be changed by the same amount as the horizontal size.

Therefore, if the figure-8 correction voltage is continuously varied, the vertical size can also be continuously varied at the same time.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the figure, l is a horizontal drive transformer.

2.3 is a resistor that controls the pace current of the transistor;
4 is a horizontal output transistor; 5 is a transistor switching in synchronization with the horizontal output transistor 4; 6.7 is a damper diode; 8 and 9 are resonance capacitors; 10 is a horizontal deflection coil; 11 12 is a figure 8 correction capacitor, and 12 is a resonance coil 13, which is a capacitor that serves as a resonance battery.

14 is a flyback transformer; 15 is a power supply for driving the horizontal deflection circuit; 16 is a transistor for changing the voltage of the capacitor 13; 17 is a resistor for varying the bias voltage of the transistor 16, that is, a size switching resistor;
18 and 19 are smoothing resistors and capacitors.

30 and 31 are vertical feedback resistors, and 33 is a vertical change coil.

36 and 37 are vertical output transistors, and the portions shown within the one-dot line are newly added portions in the present invention.

First, the operation of the horizontal size switching section will be explained.

The horizontal drive power supply 15 is voltage-divided into a capacitor 8 and a capacitor 9. Here, the average value of the figure-8 correction voltage that determines the horizontal size is equal to the average value of the voltage across the capacitor 8. Therefore, when the voltage across the capacitor 90 increases,
It is easy to see that the voltage across the capacitor 8 is reduced, the figure-8 correction voltage is also reduced, and the horizontal size can be reduced.

Therefore, since the average value of the voltage across the capacitor 90 and the average value of the voltage across the capacitor 13 are equal, the capacitor 13
By controlling the voltage across the capacitors 9 and 8,
, 11 ft can be controlled.

Therefore, in the present invention, by driving the transistor 16 from the voltage terminal, the DC voltage level of the voltage across the capacitor 130 can be freely varied.

Therefore, for the above reason, the horizontal size can be changed freely. For example, if the resistance value of the resistor 17 continues to decrease (if it becomes smaller, the voltage across the capacitor 13 increases,
If the character correction voltage becomes small, the horizontal screen size becomes smaller continuously.

Next, the vertical size switching section will be explained. As described above, when the screen size is reduced, the voltage across the capacitor 13 increases. Therefore, by smoothing the voltage across the capacitor 13 and connecting the DC voltage fluctuation to a variable impedance element, if the voltage across the capacitor 13 increases, that is, the horizontal size of the 0 screen becomes small, The impedance of the variable impedance element is made large.If the circuit is configured as described above, the impedance of the vertical feedback resistor becomes large, the vertical feedback voltage becomes large, and the vertical size can be reduced. The above size change is performed continuously.As the variable impedance element, a P-channel field effect transistor or the like can be considered.

Furthermore, it is known that according to a single circuit, a voltage corresponding to the brightness of one screen is stored in the capacitor 9.

Normally, one screen becomes brighter (the 0 screen size moves in the direction of larger). At that time, the capacitor 9 becomes brighter, so the primary winding current of the flyback transformer 140 increases, so the amount of charge increases. Therefore, according to the principle of size switching described above, one screen size is small both vertically and horizontally (
Move in the direction of (.

Therefore, it is possible to correct size fluctuations when the brightness of one screen changes.

Although the present embodiment is a circuit in which the voltage across the scene capacitor 13 is modulated by the transistor 16, it is easily understood that the same effect can be obtained even if the transistor 16 is not provided and a variable resistance element is used directly. In addition, according to the embodiment, there are six voltage detection points at both ends of the capacitor 130, but the voltage detection points are at both ends of the capacitor 130.
The same is true for the voltage across.

According to this circuit configuration, if the variable resistance element is inserted in a relatively small current section, an inductance element or the like is not used, so that the circuit can be constructed with inexpensive components.

Further, in the present invention, size switching is performed continuously using a variable resistor, but the voltage of the capacitor 13 can also be switched stepwise using a switch element. That is, one-step size switching is also possible.

Furthermore, it is easy to see that the same effect can be obtained with the diode modgierator type horizontal output circuit configuration shown in FIG.

〔Effect of the invention〕

According to the present invention, a continuous size switching circuit can be constructed using inexpensive components, and size fluctuations caused by the brightness of one screen can also be corrected.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of one embodiment of the present invention, and FIG.
4 and 4 are conventional circuit diagrams. 4...Horizontal output transistor. 18, 19... Smoothing resistor and capacitor. 16...Transistor that transmits DC voltage fluctuations. 17...Resistance for size switching. 33...Vertical deflection coil. 37, 36... Vertical output transistor. 30... Vertical size variable resistor. 2nd Akira 3rd Eye YuuΔ

Claims (1)

[Claims] 1. A flyback transformer primary coil is connected to the high voltage side of a three-way parallel circuit consisting of a horizontal output transistor connected in parallel with a damper diode, a horizontal deflection coil, an S-shaped correction capacitor series circuit, and a resonant capacitor. a horizontal output circuit in which the positive pole side of a power supply is connected, and a series circuit of a third capacitor, a transistor, a diode, an inductance, and a fourth capacitor are connected in parallel between the negative pole side of the power supply and the low voltage side of the circuit. A device is provided to vary the voltage of the fourth capacitor, and a variable impedance element is connected to the vertical feedback circuit to control the voltage variation of the fourth capacitor, thereby controlling the horizontal and vertical directions of the screen. A screen size switching circuit characterized by changing the vertical size continuously or stepwise.