JPH11261837A - Horizontal amplitude control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade the change of sensitivity despite of the change of horizontal frequency by providing a power supply voltage generation means which generates the power supply voltage that is proportional to the square of horizontal frequency as the voltage source of a rectangular wave voltage generation part. SOLUTION: A horizontal amplitude control circuit 2 which supplies the output voltage of a switching regulator circuit to a horizontal output circuit uses the power supply voltage of a horizontal dynamic focus circuit 20, for example, to generate the comparing rectangular wave voltage of the circuit 2 by a rectangular wave voltage generation part 11 as a power supply voltage generation means which generates the power voltage that is proportional to the square of horizontal frequency. The circuit 20 consists of elements Q3, D2, C2, L1 and T1 like a general horizontal deflection output circuit. The elements Q3, D2, C2 L1 and T1 function as an output transistor, a damper diode, a resonance capacitor, a deflecting coil and a focus transistor respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a horizontal amplitude control circuit in a television receiver or a monitor.

[0002]

2. Description of the Related Art A conventional horizontal amplitude control circuit in a television receiver or a monitor is configured as shown in FIG. 2, for example. In FIG. 2, reference numeral 1 denotes a triangular wave voltage generating unit that generates a triangular wave using the fixed voltage power supply Vcc as a voltage source.
2 is a power supply voltage V2 supplied to a horizontal output circuit (not shown).
Is a horizontal amplitude control circuit that controls

The collector of an NPN transistor Q4 is connected to a fixed voltage power supply Vcc via a resistor R1, and the emitter of the transistor Q4 is grounded. C3
Is a capacitor having one end connected to the non-inverting input terminal (+ terminal) of the comparator Q5, the other end connected to the collector of the transistor Q4 via the resistor R2, and grounded via the capacitor C4. I have.

At the + terminal of the comparator Q5, the triangular wave voltage (the end voltage of the capacitor C3) created by the triangular wave voltage creating unit 1 is superimposed on the F / V converted voltage V of the input horizontal signal. Voltage is supplied. The output terminal of the comparator Q5 is connected to the base of an NPN transistor Q6 which is a switching element of the switching regulator.

A voltage obtained by adjusting the input voltage Vi applied to the collector of the transistor Q6 by a switching operation is rectified and smoothed by a diode D3, a reactor L2 and a capacitor C5, and an output voltage V2 is obtained. It is supplied to the circuit as a power supply voltage.
The output voltage V2 is divided by the resistors R3 and R4 and fed back to the inverting input terminal (-terminal) of the comparator Q5.

In the circuit configured as described above, a horizontal drive pulse is supplied to the base of the transistor Q4, so that the transistor Q4 performs a switching operation in a horizontal cycle. When the transistor Q4 is off, a charging current flows to the capacitor C4 via the resistors R1 and R2,
The voltage across the capacitor C4 gradually increases.

Next, when the transistor Q4 is turned on, a discharge current flows from the capacitor C4 through the resistor R2.
The voltage across the capacitor C4 gradually decreases. That is, the voltage across the capacitor C4 is a triangular wave voltage having a horizontal period. The AC component of this triangular wave voltage is F /
The superimposed voltage is superimposed on the V conversion voltage V (F / V). The superimposed voltage is input to the + terminal of the comparator Q5, and a voltage obtained by dividing the output voltage V2 by the resistors R3 and R4 is fed back to the-terminal.

The comparator Q5 compares the voltage difference between the + terminal and the − terminal, and outputs a high level signal when the + terminal is higher than the − terminal, and outputs a low level signal when the + terminal is higher than the − terminal. That is, the comparator Q5 outputs a triangular-wave frequency pulse input to the + terminal to drive the transistor Q6.

Therefore, transistor Q6 performs a switching operation to interrupt power supply voltage Vi. A DC voltage obtained by smoothing the pulse voltage by the reactor L2 and the capacitor C5 is output as V2. V2 is stabilized to a voltage that is the resistance of the DC component of the voltage input to the + terminal of the comparator Q5, which is R3 or R4.

[0010]

In the circuit of FIG.
The comparison triangular wave voltage of the horizontal amplitude control circuit has been created based on a fixed voltage power supply Vcc which does not change with the horizontal frequency. The output voltage of the horizontal amplitude control circuit becomes a voltage proportional to the horizontal frequency. Therefore, the voltage fed back to the comparator of the horizontal amplitude control circuit also becomes a voltage proportional to the horizontal frequency. Therefore, unless the amplitude of the triangular wave voltage superimposed on the reference DC voltage input to the comparator Q5 of the horizontal amplitude control circuit 2 in the circuit of FIG. 2 is also made proportional to the horizontal frequency, the sensitivity of the horizontal amplitude control circuit 2 depends on the horizontal frequency. There was a problem that it changed.

The present invention has been made in view of the above points, and an object of the present invention is to provide a horizontal amplitude control circuit whose sensitivity does not change even if the horizontal frequency changes.

[0012]

(1) In order to solve the above problems, the present invention provides a switching regulator circuit,
A triangular-wave voltage generating unit that generates a triangular wave using a predetermined power supply voltage as a voltage source; a voltage obtained by superimposing a triangular-wave voltage of the triangular-wave voltage generating unit on an F / V conversion voltage of an input horizontal signal; A horizontal amplitude control circuit that compares the output voltage of the circuit with a feedback voltage, controls a switching element of the switching regulator circuit by the deviation output signal, and supplies an output voltage of the switching regulator circuit to a horizontal output circuit.

[0013] As the voltage source of the voltage generator in the triangular wave,
A power supply voltage generating means for generating a power supply voltage proportional to the square of the horizontal frequency;

The power supply voltage generating means is constituted by a horizontal dynamic focus circuit.

The horizontal dynamic hocus circuit switches the primary side of the hocus transformer at a horizontal cycle,
A parabola voltage having a constant amplitude is output from the secondary side of the transformer, and a power supply voltage supplied to the primary side of the transformer is controlled by a deviation signal between a voltage fed back from the parabola voltage and a reference voltage. It is characterized by:

(2) Since the power supply voltage of the horizontal dynamic hocus circuit is proportional to the square of the horizontal frequency, the amplitude of the triangular wave voltage generated using the voltage is proportional to the horizontal frequency. For this reason, the switching element of the switching regulator circuit compares the voltage obtained by superimposing the triangular wave voltage whose amplitude is proportional to the horizontal frequency on the F / V conversion voltage of the horizontal signal, and the voltage obtained by feeding back the output voltage of the switching regulator circuit. Switching control is performed by the deviation output.

As a result, the output voltage of the switching regulator circuit also becomes a voltage proportional to the horizontal frequency. Therefore, the amplitude of the F / V conversion voltage of the input horizontal signal also becomes
The amplitude of the triangular wave voltage superimposed on the voltage is also proportional to the horizontal frequency, and the sensitivity of the horizontal amplitude control circuit remains constant even when the horizontal frequency changes.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the present invention, a power supply voltage generating means for generating a power supply voltage proportional to the square of the horizontal frequency, for example, a power supply voltage of a horizontal dynamic hocus circuit as shown in FIG. It was configured to create. 1, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, reference numeral 20 denotes a horizontal dynamic focus circuit, and a portion composed of Q3, D2, C2, L1, and T1 has the same configuration as a general horizontal deflection output circuit. Output transistor, D2
Is a damper diode, C2 is a resonance capacitor, L1 is a deflection coil, and T1 is a hocus transformer.

Since a horizontal drive pulse is supplied to the base of the transistor Q3, the transistor Q3 performs a switching operation in synchronization with the horizontal frequency, and the deflection coil L1 and the hocus transformer T1 have the same deflection current as that of the horizontal deflection circuit. A sawtooth current flows. Since both ends on the secondary side of the hocus transformer T1 are short-circuited by the capacitor C1,
Since a current equal to one-turn ratio of the sawtooth current flowing to the primary side of the hocus transformer T1 flows through the capacitor C1, a parabolic voltage obtained by integrating the sawtooth current is generated at both ends of the capacitor C1.

The amplitude of the parabolic voltage is determined by the error amplifier Q2.
To perform comparison amplification with the reference voltage by the Zener diode D1 to control the transistor Q1. Therefore, the transistor Q1 outputs the output voltage V1 (deflection coil L
1. By controlling the power supplied to the hocus transformer T1, the operation is performed so that the amplitude of the output parabola voltage Vout is constant.

Since the capacity of the capacitor C1 is fixed,
In order to make the amplitude of the parabolic voltage (Vout) at both ends constant regardless of the frequency, it is necessary to increase or decrease the amplitude of the sawtooth current flowing through the capacitor C1 in proportion to the frequency. In order to make the sawtooth current flowing in the capacitor C1 proportional to the frequency, it is necessary to make the primary side sawtooth current of the hocus transformer T1 proportional to the frequency. Needs to make the power supply voltage V1 proportional to the square of the frequency. Therefore, if control is performed so that the amplitude of the output parabola voltage is constant regardless of the frequency, the power supply voltage V1 becomes a voltage that changes in proportion to the square of the frequency.

As described above, the input power supply voltage V1 of the horizontal deflection output circuit of the horizontal dynamic focus circuit 20, which is proportional to the square of the horizontal frequency, is supplied to the collector of the transistor Q4 via the resistor R1 as a voltage source of the triangular wave voltage generator 11. Applied.

Since a horizontal drive pulse is supplied to the base of the transistor Q4, the transistor Q4 performs a switching operation in a horizontal cycle. When the transistor Q4 is off, a charging current flows to the capacitor C4 via the resistors R1 and R2, and the voltage across the capacitor C4 gradually increases.

Next, when the transistor Q4 is turned on, a discharge current flows from the capacitor C4 through the resistor R2.
The voltage across the capacitor Q4 gradually decreases. That is, the voltage across the capacitor C4 is a triangular wave voltage having a horizontal period. The amplitude of the triangular wave voltage increases in proportion to the power supply voltage V1, and decreases in proportion to the horizontal frequency.

Since the power supply voltage V1 is proportional to the square of the horizontal frequency as described above, the amplitude of the triangular wave voltage generated across the capacitor C4 is proportional to the horizontal frequency. The AC component of the triangular wave voltage is superimposed on the F / V conversion voltage V (F / V) by the capacitor C3, and the superimposed voltage is equal to +
Input to the terminal.

As described with reference to FIG. 2, a voltage obtained by dividing the output voltage V2 by the resistors R3 and R4 is fed back to the negative terminal of the comparator Q5. The voltage difference is compared. When the + terminal is higher than the − terminal, a high level signal is output, and when the + terminal is opposite, a low level signal is output.
That is, the comparator Q5 outputs a triangular-wave frequency pulse input to the + terminal to drive the transistor Q6.

Therefore, transistor Q6 performs a switching operation to interrupt power supply voltage Vi. A DC voltage obtained by smoothing the pulse voltage by the reactor L2 and the capacitor C5 is output as V2. V2 is stabilized to a voltage that is the resistance of the DC component of the voltage input to the + terminal of the comparator Q5, which is R3 or R4.

Since the DC level at the + terminal of the comparator Q5 is an F / V conversion voltage proportional to the horizontal frequency, V2 is also a DC voltage proportional to the horizontal frequency. The DC level of the voltage input to the comparator Q5 is proportional to the horizontal main fraction, and the amplitude of the triangular wave superimposed on the DC level is also proportional to the horizontal frequency. It will be constant.

The power supply voltage generating means of the present invention is not limited to the dynamic focus circuit, but may use another circuit.
Further, in the present invention, the primary power supply of the dynamic focus circuit is applied to the horizontal amplitude control circuit by utilizing the fact that the primary power supply is proportional to the square of the horizontal frequency. It is needless to say that the present invention is effective for a circuit requiring a DC voltage.

[0031]

According to the present invention, the effect that the sensitivity does not change even when the horizontal frequency changes can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional horizontal amplitude control circuit.

[Explanation of symbols]

1,11 Triangular wave voltage generator 2 Horizontal amplitude control circuit 20 Power supply voltage generator (horizontal dynamic focus circuit) Q1, Q3, Q4, Q6 Transistor Q2 Error amplifier Q5 Comparator T1 Hocus transformer L1 Deflection coil C1 Capacitor

Claims (3)

[Claims] 1. A switching regulator circuit, and a triangular-wave voltage generator for generating a triangular wave using a predetermined power supply voltage as a voltage source, wherein the triangular wave of the triangular-wave voltage generator is converted into an F / V conversion voltage of an input horizontal signal. A voltage obtained by superimposing a voltage is compared with a voltage to which the output voltage of the switching regulator circuit is fed back, and a switching element of the switching regulator circuit is controlled by the deviation output signal, and an output voltage of the switching regulator circuit is output to a horizontal output circuit. A horizontal amplitude control circuit, comprising: a power supply voltage generating means for generating a power supply voltage proportional to the square of a horizontal frequency as a voltage source of the triangular wave voltage generating unit. 2. The horizontal amplitude control circuit according to claim 1, wherein said power supply voltage generating means is constituted by a horizontal dynamic focus circuit. 3. The horizontal dynamic hocus circuit according to claim 1,
The primary side of the hocus transformer is switched at a horizontal cycle, a parabola voltage having a constant amplitude is output from the secondary side of the transformer, and the parabola voltage is fed back to the primary side of the transformer by a deviation signal between a voltage fed back and a reference voltage. 3. The horizontal amplitude control circuit according to claim 2, wherein the power supply voltage is controlled.