JPH03177166A - Horizontal pattern width control circuit - Google Patents

Abstract

PURPOSE:To automate the adjustment on the production line by controlling a power voltage in response to the result of comparison between a horizontal pattern width control signal of a DC voltage from a control circuit and a rectified output at the secondary winding of a horizontal output transformer so as to save a variable resistor in a conventional circuit. CONSTITUTION:When a horizontal pattern width control signal Sc from a control circuit 14 is decreased, an output of an inverting adder 10 is increased, the output of an inverse amplifier 11 is decreased, the feedback voltage to a power supply circuit 13 is decreased and an output voltage of the power supply circuit 13 is increased as the constitution. As a result, since a deflection current flowing to a horizontal deflection coil 5 is increased, the width of the horizontal pattern is spreaded. Since the voltage of the secondary winding 7 of the horizontal output transformer is increased, the inverting input voltage to the inverse adder 10 is increased and a nearly constant feedback voltage in the steady state is outputted finally. Thus, no variable resistor is required and the correspondence to the horizontal pattern width in plural horizontal frequencies is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a horizontal screen width control circuit used in display monitor devices and the like.

[Conventional technology]

FIG. 2 is a circuit diagram showing a conventional horizontal screen width control circuit. In the figure, 1 is a horizontal output transistor, 2 is a damper diode connected in parallel to the transistor l, and 3
is a resonance capacitor connected in parallel to the damper diode 2, 5 is a horizontal deflection coil through which the horizontal deflection current flows, and 6
4 is the primary winding of the horizontal output transformer connected to the transistor 1 and other circuit elements; 13 is the circuit through the primary winding 4; A power supply circuit that supplies power supply voltage to
5 is a volume for adjusting the power supply voltage.

Next, the operation will be explained.

Transistor 1 is turned on and off by applying a drive pulse to the base of transistor 1 from a previous horizontal drive circuit (not shown). During the horizontal scanning period, when transistor 1 is on, current flows from capacitor 6 to transistor 1 through horizontal deflection coil 5, and when transistor 1 is off, current flows from damper diode 2 through horizontal deflection coil 5 to capacitor 6. . Further, during the horizontal retrace period, an oscillating current flows due to the resonance frequency of the circuit inductance and the capacitor 3.

To control the horizontal screen width, the power supply voltage of the power supply circuit 13 applied to the primary winding 4 of the horizontal output transformer is generally made variable by adjusting the power supply voltage adjustment volume 15, and the power supply voltage applied to the horizontal deflection coil 5 is made variable. The horizontal screen width is controlled by changing the deflection current that flows.

In addition, as a technique related to this invention, for example, Japanese Patent Laid-Open No. 58
-84570 publication, JP 63286071 publication,
JP-A-61-96835, JP-A-61-9683
There are some disclosed in Japanese Patent Publication No. 6, Japanese Patent Application Laid-Open No. 1-138588, and the like.

[Problem to be solved by the invention]

Since the conventional horizontal screen width control circuit is configured as described above, it is necessary to provide the volume 15 and adjust the volume 15, and in order to correspond to the horizontal screen width at multiple horizontal frequencies, it is necessary to provide the volume 15 and adjust the volume 15. , there were issues such as the need to provide multiple volumes and switch between them.

This invention was made to solve the above-mentioned problems, and aims to provide a horizontal screen width control circuit that can eliminate volume and also handle horizontal screen widths at multiple horizontal frequencies. .

[Means to solve the problem]

The horizontal screen width control circuit according to the present invention compares the rectified output of the secondary side of the horizontal output transformer with a horizontal screen width control signal consisting of a DC voltage from the control circuit, and controls the power supply voltage according to the comparison result. It was designed to do so.

[For production]

The horizontal screen width control signal in this invention is output as a DC voltage from a control circuit equipped with a microcomputer, and the comparison result between this horizontal screen width control signal and the rectified output on the secondary side of the horizontal output cadence is fed back to the power supply circuit. As a result, the power supply voltage is controlled so that the comparison result is constant.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and explanations thereof will be omitted.

In Figure 1, 7 is the secondary winding of the horizontal output transformer, 8
is a diode that rectifies the voltage obtained at the secondary winding 7, 9
is a capacitor that smoothes the output of the diode 8, and together with the diode 7 constitutes a rectifier circuit. 14 is a control circuit that is accessed by an external access human input signal SA and outputs a horizontal screen width control signal SC consisting of a DC voltage, and is composed of a microcomputer, a memory consisting of an E"PROM, a D/A converter, etc. 10 is an inverting adder that compares the DC output voltage of the rectifier circuit with the horizontal screen width control signal Sc, and 11 is an inverting amplifier that inverts the output of the inverting adder 10, which together with the inverting adder 10 constitutes a comparison circuit. The output voltage of this comparison circuit is fed back to the power supply circuit 13 to control the power supply voltage applied to the primary winding 4 of the horizontal output transformer.12 is an inverting adder. 10 and inverting amplifier 1
1 reference voltage.

Next, the operation will be explained.

When the horizontal screen width control signal S from the control circuit 14 is decreased, the output of the inverting adder 10 increases and the output of the inverting amplifier 11 decreases. Then, the feedback voltage to the power supply circuit 13 decreases, and the output voltage of this power supply circuit 13 increases. As a result, the deflection current flowing through the horizontal deflection coil 5 increases, so that the horizontal screen width increases. Also,
Since the voltage of the secondary winding 7 of the horizontal output transformer also increases,
The inverting input voltage to the inverting adder 10 also increases, and a substantially constant feedback voltage is finally output in the steady state.

Further, a plurality of horizontal screen width control signals Sc for a plurality of horizontal frequencies can be prepared in advance in the memory of the control circuit 14, and read out by the external access input signal SA. As the external access input signal SA, a signal from an automatic horizontal screen width adjustment device or the like or a signal from a keyboard or the like can be used.

Note that in the above embodiment, an inverting adder 10 and an inverting amplifier 11 are provided to compare the secondary voltage of the horizontal output drance with the horizontal screen width control signal SC from the control circuit 14, but these Alternatively, one non-inverting adder may be provided.

〔Effect of the invention〕

As described above, according to the present invention, the voltage is controlled according to the comparison result between the horizontal screen width control signal consisting of the DC voltage from the control circuit and the rectified output on the secondary side of the horizontal output transformer. Because of this configuration, it is possible to omit the conventional volume, and it is also possible to automate adjustment on the production line, and there is no need to provide a number of volumes corresponding to multiple horizontal frequencies, and the control circuit can handle multiple horizontal screen widths. By preparing control signals, it is possible to obtain effects such as being able to deal with the problem.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a horizontal screen width control circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional horizontal screen width control circuit. 4 is the primary winding of the horizontal output cadence, 7 is the secondary winding of the horizontal output cadence, 8 is a rectifying diode, 9 is a smoothing capacitor, 10 is an inverting adder, 11 is an inverting amplifier, 1
3 is a power supply circuit, and 14 is a control circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A rectifier circuit provided on the secondary side of the horizontal output transformer,
a control circuit that outputs a horizontal screen width control signal consisting of a DC voltage; a comparison circuit that compares the DC output voltage of the rectifier circuit with the horizontal screen width control signal; and a power supply voltage controlled by the output voltage of the comparison circuit. and a power supply circuit that supplies the primary winding of the horizontal output transformer.