JPH06209421A - Horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To obtain a horizontal deflection circuit in which an AC ripple voltage produced by a high voltage output section is not fed back to an input voltage control means by feeding back negatively an output of the input voltage control means to a control terminal. CONSTITUTION:An output of an input voltage control circuit 4 is fed to an inverting input terminal of an inverting amplifier 3 in a feedback loop via a filter circuit 10 comprising a serial circuit of a capacitor 7 and a resistor 8. Thus, an AC ripple component included in a detected voltage is cancelled at the inverting input terminal in the inverting amplifier circuit 3. Then the inverting amplifier circuit 3 is activated by a detection voltage not including an AC clip voltage and then the input voltage control circuit 4 is controlled. Thus, an output voltage of the input voltage control circuit 4 does not include the AC ripple component.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a horizontal deflection circuit.

[0002]

2. Description of the Related Art Conventionally, in an integrated horizontal deflection circuit system in which a high voltage output part and a horizontal output part of a flyback transformer are connected to the same switching circuit, the image size is changed by the change of the load current of the high voltage output part. In order to prevent change, the voltage divided by the bleeder resistance on the secondary side of the flyback transformer is detected and fed back to the input voltage control circuit of the horizontal deflection circuit to make the output of the high voltage output unit constant. Therefore, the input voltage control circuit is operating.

The circuit configuration will be described in more detail with reference to FIG. The horizontal output circuit (5) is composed of a horizontal output transistor (9), a diode modulation circuit, which will be described later, and a horizontal deflection coil. The output of the horizontal output circuit (5) is the primary of the flyback transformer (1). Applied to the side coil. The switching operation of the horizontal output transistor (9) is controlled by the output of a horizontal drive circuit (not shown). By the bleeder resistance (2) of the secondary coil of the flyback transformer (1),
Detect high voltage output. This detection voltage is applied to the inverting amplifier (3)
It is fed back to the control terminal of the input voltage control circuit (4) via. The horizontal output circuit (5) includes a so-called diode modulation circuit having two resonance circuits, and a load flowing to the secondary side of the flyback transformer (1) via the horizontal amplitude control circuit (6). The horizontal amplitude is controlled to be constant by the voltage that detects the current. This is because when the high voltage load current increases, the output of the horizontal voltage control circuit (4) rises and feedback is applied so as to keep the high voltage output constant, so that the horizontal amplitude expands. Therefore, the high-voltage load current is detected, and through the horizontal amplitude control circuit (6),
The control is performed so as to cancel out the increase in horizontal amplitude.

However, an AC ripple voltage, which is high in the vertical blanking period and low in the video period, is superimposed on the voltage detected by dividing the high voltage output of the flyback transformer (1). The phase of this voltage is delayed due to the time constant in the feedback loop, and becomes a ripple voltage as shown in FIG. 3B, and the input voltage control circuit (4).
Be returned to. . Therefore, there is a drawback that the image is bent in the horizontal direction in proportion to the ripple voltage.

[0005]

In the conventional circuit, the AC ripple voltage generated in the high voltage output section is fed back to the input voltage control circuit as it is, so that the image is bent in the horizontal direction.

An object of the present invention is to provide a horizontal deflection circuit which does not feed back the AC ripple voltage generated in the high voltage output section to the input voltage control circuit.

[0007]

A flyback transformer in which a primary coil is connected to an output terminal of the horizontal output circuit, and a control terminal is connected to a secondary coil of the flyback transformer to connect a primary coil to the primary coil. Input voltage control means for connecting an output terminal and controlling an input voltage input to a primary side coil of the flyback transformer based on a high-voltage output voltage of the flyback transformer, and a primary of the flyback transformer. The input voltage input to the side coil is negatively fed back to the control terminal of the input voltage control means, and the negative feedback means for removing an unnecessary component superimposed on the high voltage output voltage is constituted.

[0008]

The input voltage input to the primary coil of the flyback transformer, that is, the output of the input voltage control means is negatively fed back to the control terminal of the input voltage control means, and is applied to the control terminal. The unnecessary component superimposed on the high voltage output voltage can be removed.

[0009]

EXAMPLE An example of the present invention will be described with reference to FIG.
The same parts as those in the conventional example of FIG. 2 are designated by the same reference numerals.
The bleeder resistance (2) of the flyback transformer (1) converts the detection voltage proportional to the high voltage output to the inverting amplifier (3).
To enter. The output of the inverting amplifier (3) controls the input voltage control circuit (4). The output of the input voltage control circuit (4) is supplied to the inverting input terminal of the inverting amplifier circuit (3) in the feedback loop via the filter circuit (10) consisting of the series circuit of the capacitor (7) and the resistor (8). . This allows
The AC ripple component contained in the detection voltage is canceled at the inverting input terminal of the inverting amplifier circuit (3). And
The inverting amplifier circuit (3) is operated by the detection voltage not including the AC ripple voltage, and then the input voltage control circuit (4)
To control. As described above, the output voltage of the input voltage control circuit (4) does not include the AC ripple component. The other parts are the same as the conventional ones, and thus the description thereof is omitted.

[0010]

According to the present invention, since the detection voltage supplied to the control input of the input voltage control circuit does not contain an AC ripple component, the output of the high voltage output section is stable and the horizontal image is not bent. No horizontal deflection circuit can be achieved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a horizontal deflection circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional horizontal deflection circuit.

FIG. 3 is a waveform diagram showing an AC ripple component supplied to a control terminal of a conventional input voltage control circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flyback transformer, 2 ... Bleeder resistance, 3 ... Inversion amplification circuit, 4 ... Input voltage control circuit, 5 ... Horizontal output circuit, 6 ... Horizontal amplitude control circuit, 7 ... Capacitor, 8 ... Resistor, 9 ... Horizontal output transistor , 10 ... Filter circuit

Claims (1)

[Claims] 1. A horizontal output circuit including a deflection coil, a flyback transformer in which a primary coil is connected to an output terminal of the horizontal output circuit, and a control terminal is connected to a secondary coil of the flyback transformer. Input voltage control means for connecting an output terminal to the primary side coil and controlling an input voltage input to the primary side coil of the flyback transformer based on a high output voltage of the flyback transformer; Negative feedback means for negatively feeding back the input voltage input to the primary side coil of the back transformer to the control terminal of the input voltage control means, and removing the unnecessary component superimposed on the high voltage output voltage. And horizontal deflection circuit.