JPS596028Y2 - Vertical output circuit device - Google Patents

Description

[Detailed explanation of the invention] This invention is a single-ended push-pull circuit (hereinafter referred to as SEP).
This relates to a vertical output circuit device of a television receiver constructed with a P circuit (referred to as a P circuit), and is intended to prevent the signal generated at the break of switching operation from interfering with the screen by simple means. .

FIG. 1 shows a vertical output circuit having a conventional SEPP structure.

In the figure, 1 and 2 are respective output transistors, and 3 is the emitter of the output transistor 1 and the output transistor 2.
5, 6.7 are bias resistors of the output transistor 1, 8, 9 are each an emitter resistor and a collector resistor, 10 is a bootstrap capacitor, 11. 12 is a diode and a capacitor for increasing the retrace pulse voltage, 13.14 is a base bias resistor and an emitter resistor for each output transistor 2, and 15.16 is a base of output transistor 1 for transmitting the signal appearing at the collector of output transistor 2. These are capacitors and resistors for supplying

The base of the output transistor 2 and the connection point between the emitter resistor 8 and the collector resistor 9 are connected to a vertical drive circuit.

To briefly explain the operation of the above structure, when the vertical drive signal shown in FIG. 1 is applied to the base of the output transistor 2, a base current flows and a collector current flows. In order to perform class AB amplification operation, the collector current increases significantly in the second half of the scan to flow half a cycle of the deflection coil current.

On the other hand, the output transistor 1 performs a class B amplification operation, and the sawtooth wave appearing at the collector of the output transistor 2 is applied to its base via the capacitor 15 and the resistor 16, making the output transistor 1 conductive.

As a result, current flows from the power source to the deflection coil 3 via the diode 11, output transistor 1, resistor 8, and capacitor 4, forming the first half of the deflection coil current.

Since the capacitor 4 is charged by this current, the emitter voltage of the output transistor 1 becomes high and the output transistor 1 is cut off.

On the other hand, the output transistor 1 is conductive during the period T2 of the vertical drive signal, and the charge in the capacitor 4 flows through the resistor 9, the output transistor 2, the resistor 14, and the deflection coil 3.
This is the latter half of the deflection coil current.

However, in the conventional structure as described above, since the output transistor 1 performs a switching operation, at the moment it is cut off, a narrow pulse in the negative direction and a large amplitude is generated at the emitter of the output transistor 1. .

This is considered to be caused by a transient operation due to excessive electron emission during cutoff due to switching operation.

However, this pulse appears a little later than in the central part of the vertical scanning period when the output transistor 2 is conducting, and because this pulse or its harmonics mix into the video circuit due to mutual induction between circuits, etc. However, as shown in FIG. 3, horizontal stripes A appear on the screen, making the image unsightly.

The present invention attempts to eliminate this interference signal, and the second
As shown in the figure, a capacitor 17 for removing interference signals is connected between the emitter of one output transistor 1 and the ground.

As a result, the pulse-like interference signal generated at the emitter when the output transistor 1 is cut off can be released to the ground by the high-pass action of the capacitor 17, and it is possible to prevent the interference signal from entering the video circuit. Since horizontal stripes can be prevented from appearing on the screen, an easy-to-read screen can be obtained.

As explained above, according to the present invention, by connecting a capacitor between the emitter of one of the output transistors constituting the SEPP circuit and the ground, interference signals generated during the switching operation of the output transistor can be removed. This makes the screen easier to view.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional vertical output circuit device, Fig. 2 is a circuit diagram of a vertical output circuit device according to an embodiment of the present invention, and Fig. 3 is a diagram showing the influence of the conventional device on the screen. . 1, 2... Output transistor, 3...
Deflection coil, 4... Capacitor, 17...
...Capacitor for removing interference signals.

Claims (1)

[Scope of utility model registration request] The emitter of the first output transistor and the collector of the second output transistor are connected, the collector of the first output transistor and the emitter of the second output transistor are connected to a power supply and ground, respectively, and the first and second output transistors are connected to each other. A deflection coil is connected to the connection point between the collector and emitter of the output transistor through a capacitor, and a vertical drive signal is applied between the collector and emitter connection point of the first and second output transistors and the base of the second output transistor. is applied, and a capacitor for removing interference signals is connected between the emitter of the first output transistor and ground.