JPS6235781A - Horizontal driving circuit - Google Patents

Abstract

PURPOSE:To prevent a driving element and parts from overheating and to maintain the linearity of a horizontal screen by constituting a horizontal driving circuit which has a horizontal pulse oscillator as its front stage, and feeding the output of a driving element back to the horizontal pulse oscillator through a horizontal pulse width modulator and controlling pulse width. CONSTITUTION:A circuit which detects an output pulse of a driving transistor(TR) 2 and feeds it back to the horizontal pulse oscillator 1 through the horizontal pulse width modulator 13 is provided. Namely, the output pulse of the driving TR 2 is detected by a coil L3, a DC level is obtained by the smoothing circuit composed of a serial diode D2 and a parallel capacitor C3 and inputted to a comparing circuit 12 together with a standard level 11 obtained from the voltage division point between resistances R4 and R5 between VB and the ground, and a modulated signal is fed back t the control terminal of the horizontal oscillator 1 consisting of, for example, a multivibrator according to the detected DC level is larger or smaller than the standard level, thereby increasing or decreasing the pulse width. Consequently, the output pulse width of the driving TR 2 is nearly equalized to a specific value and made constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Summary) The present invention provides a horizontal pulse oscillator in which a horizontal pulse oscillator of a display device or the like is installed in front, and its output is input to a drive element (1) - an output pulse having a predetermined duty is supplied to a horizontal output circuit. In the drive circuit, the output of the drive element is fed back to the horizontal pulse oscillator via a horizontal pulse width modulator, and the current flowing through the drive element t is automatically adjusted to be optimum.

[Industrial application field]

The present invention relates to a horizontal drive circuit for a display device, etc., and more particularly to a horizontal drive circuit that automatically adjusts the duty of output pulses of drive elements.

[Conventional technology]

FIG. 2 shows an example of a horizontal drive circuit conventionally included in display devices and TV devices of various systems.

In the same figure, a horizontal synchronizing signal (H8
) is inserted into the horizontal pulse oscillator IK to generate a pulse synchronized with H8, which is manually turned on and off via the resistor R1 to the base of the drive transistor 20 of the horizontal drive circuit 4, and connected in parallel with the primary coil L1 of the coupling transformer Tl. (resistance R2+
A resonant circuit 6 consisting of a capacitor 01) and υ is provided on the output side,
A drive waveform output having a predetermined voltage and duty is sent to the horizontal output circuit 6. That is, the capacitor C2 is connected to the transistor 5 from the secondary coil L2 of the coupling transformer T1 through the resistor 3 and connected in parallel to the collector.
and a diode D, and as a load side, series resonance is performed for the flyback transformer 7 added to the ORT display tube to generate a high voltage on its secondary side, and parallel resonance is performed for the deflection coil 8 to generate an appropriate voltage. horizontal deflection current.

[Problem that the invention seeks to solve]

In the configuration of the conventional horizontal drive circuit described above, the duty of the drive pulse and the rise of the pulse 9. A change occurs in the slope of the falling slope. In this case, assuming that the generated voltage of the resonant circuit is, for example, about I KV, when the current pulse is one person, and the duty becomes 1 Å or more, if the slope becomes gentle, the heat loss in the two parts of the element will decrease. There will be a sudden increase in the number of units and there will be a risk of destruction. Therefore, it is desirable to perform control to maintain a steep pulse that meets the required duty.

An object of the present invention is to adjust the duty of the output pulse of the driving element by m% so that it is constant in a horizontal driving circuit that is provided with a horizontal pulse oscillator.

[Failure to solve the problem]

In order to achieve the above object, the present invention provides a horizontal drive circuit which is provided with a horizontal pulse oscillator, and is provided with a circuit that feeds back the output of the drive element to the horizontal pulse oscillator via a horizontal pulse width modulator. be.

[For production]

The above horizontal pulse width modulator automatically adjusts the pulse width by comparing the duty of the output pulse of the driving element with the base rlt value and controlling the horizontal pulse oscillator depending on whether it is larger or smaller. It is.

〔Example〕

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention.

2, the difference from the conventional example shown in FIG. 2 is that a circuit is provided to detect the output pulse of the driving transistor 2 and feed it back to the horizontal pulse oscillator 1 via the horizontal pulse width modulator 16. That is, the output pulse of the driving transistor 2 is detected by the coil L3, the DC level is obtained by a smoothing circuit composed of a series diode D and a parallel capacitor 03, and the DC level is obtained by a resistor 4. The standard level 11 obtained from the voltage division point of the filter 5 is input into the comparator circuit 12, and the modulation signal is sent to the horizontal oscillator 1, which is made of a multivibrator, for example, depending on whether the detected Do level is larger or smaller than the standard level. It returns to the control terminal and increases or decreases the pulse width.

As a result, the output pulse width of the driving transistor 2 can be kept constant near the specified value.

〔Effect of the invention〕

As explained above, according to the present invention, in a horizontal drive circuit provided with a horizontal pulse oscillator, the output of a drive element is fed back to the horizontal pulse oscillator via a horizontal pulse width modulator to control the pulse width. . This makes it possible to prevent overheating of the drive elements and components, and is also effective in maintaining the linearity of the horizontal screen.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, and Fig. 2 is an explanatory diagram of the configuration of a conventional example.
is a driving transistor, 3 is a resonant circuit, 4 is a horizontal drive circuit, 5 is a transistor, 6 is a horizontal output circuit, 7 is a flyback transformer, 8 is a deflection coil, 11 is a reference level,
12 is a comparison circuit, and 13 is a horizontal pulse width modulator.

Claims (1)

[Claims] An oscillator that inputs the horizontal synchronizing signal extracted from the image signal and generates horizontal pulses in synchronization with the horizontal synchronizing signal is installed in front, and the output of the oscillator is input to the driving element, and the output pulses having a predetermined duty are outputted horizontally from the CRT display tube. In the horizontal drive circuit that supplies the circuit, a circuit is provided for feeding back the output of the drive element to the horizontal pulse oscillator via a horizontal pulse width modulator, and the duty of the output pulse of the drive element is automatically adjusted. horizontal drive circuit.