JPS62130073A - Deflection circuit - Google Patents

Abstract

PURPOSE:To keep constantly the duty of the output horizontal oscillating pulse of a horizontal oscillation circuit substantially constant and to prevent the deficiency in driving a horizontal output circuit and a turbulence of the deflection by changing the pulse duration of a horizontal oscillation pulse according to the frequency of a horizontal synchronizing signal. CONSTITUTION:If the frequency of the input horizontal synchronizing signal is moved to a low frequency side within a previously expected frequency range, the output of a frequency/voltage conversion circuit 3 is reduced, and the negative electrode output of a control circuit 13 increases an absolute value and is reduced. Therefore, the collector current of a transistor (TR)Q2 for varying a charging current in a monostable multibrator 12 is reduced and a charging time in a capacitor C is increased. As a result, tough the duty of the output of the horizontal oscillation circuit 2 is lower than 50%, the output of the vibrator 12, namely the duty of the horizontal oscillating pulse is maintained substantially at 50%. Accordingly, the on time of the horizontal output TR in the horizontal output circuit 5 is substantially equal to an off time, even when the input horizontal synchronizing signal is moved to the low frequency and the deficiency in driving or the stop of driving of the circuit 5 can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection circuit suitable for a multi-scan monitor.

[Conventional technology]

For multi-scan monitors whose deflection frequency changes depending on the signal source, the horizontal oscillation frequency of the signal source is Automatically follows the oscillation frequency. A deflection circuit 1 shown in Fig. g3 is provided.

In this deflection circuit 1, a horizontal synchronizing signal that has been synchronously separated or directly input from the outside is connected to an IC such as μPB]377C.
while the frequency 4 is supplied to the horizontal oscillation circuit 2 consisting of
It is supplied to the positive conversion circuit 3. The frequency/1 positive conversion circuit 3 generates a voltage that is approximately inversely proportional to the frequency of the input horizontal synchronizing signal, and this voltage is sent to the excavation control input of the horizontal oscillation circuit 2 via the voltage/current conversion circuit 4. Supplied to the terminal.

The horizontal oscillation circuit 2 forms a horizontal oscillation pulse by comparing the sawtooth wave formed by being triggered by the input horizontal synchronization signal with the first current supplied to the excavation control input terminal, and generates the horizontal excavation pulse. It is supplied to the horizontal output circuit 5 at the subsequent stage.

The horizontal output circuit 5 once amplifies the horizontal oscillation pulse from the horizontal oscillation circuit 2 to a predetermined signal level, and then applies it to the base of a horizontal output transistor (not shown) to drive the horizontal output transistor on and off. and a sawtooth deflection ME flow to a horizontal deflection coil (not shown).

[The problem that invention attempts to solve]

The above conventional deflection circuit 1 can be opened horizontally by one person! For example, the configuration is such that multi-scanning is possible in the range of 15 to 34 kHz as the frequency of the 8 signals, but the higher the frequency of the input horizontal dokanraku signal, the higher the level of the 4 current signal provided to the excavation control input terminal becomes. To decrease.

The tute of the horizontal oscillation pulse output from the horizontal oscillation circuit 2 increases by more than 50%.

As a result, there were problems such as rounding, where the off time of the horizontal output transistor in the horizontal output circuit 5 became shorter while the on time became longer, and the switching operation of the horizontal output transistor was disturbed due to effects such as the accumulated single load effect. . Also, on the contrary, the input horizontal synchronization signal is low lI! As t1 increases, the duty of the horizontal oscillation pulse falls below 50%, resulting in increased power loss and, in the worst case, the horizontal output circuit 5 may stop operating. there were.

[Means for solving problems]

This optical power solves the above-mentioned drawback, and is connected between a horizontal oscillator circuit that outputs horizontal miss pulses with different duties depending on the frequency of the input horizontal synchronization signal, and between this horizontal excavation circuit and the horizontal output circuit. l is provided.

The gist of the present invention is to provide a correction means for changing the pulse width of the horizontal oscillation pulse in accordance with the frequency of the horizontal synchronizing signal and making corrections that sufficiently satisfy the deflection output conditions and drive conditions. be.

[Effect]

In this invention, the duty of the output horizontal oscillation pulse of the horizontal excavation circuit, which changes according to the frequency a of the input horizontal synchronization signal, is
By changing the pulse width of the horizontal miss pulse according to the frequency of the horizontal synchronization signal, the pulse width is kept almost constant at all times,
Prevents insufficient driving of the horizontal output circuit and disturbances in deflection.

〔Example〕

Hereinafter, four examples of the present invention will be explained with reference to FIG. 1.2. FIG. 1.2 is a circuit configuration diagram and a signal waveform diagram of each part of the circuit, respectively, showing one embodiment of the deflection circuit of the present invention.

In FIG. 1, the deflection circuit 11 includes a monostable multivibrator 12 between the horizontal oscillation circuit 2 and the horizontal output circuit 5, and a control circuit 13 for variable control of the holding time of the monostable multivibrator 12. , frequency/bottom pressure f
The circuit configuration is connected to the aB path 3.

In the monostable multivibrator 12, a transistor Q1, to which the horizontal oscillation pulse output from the horizontal oscillation circuit 2 is applied to the base, is connected to the clock input 1 through the connection point between the emitter resistor R+ and R1. IC14 (IC name 7
4LS123).

This LC14f has a holding time corresponding to 1 hour when the capacitor C is charged. Unconnected battery 1 of capacitor C
The JIII terminal is connected to the connection point of the voltage dividing resistors R8, R, and the collector of the transistor Q for converting the first charging OT. The emitter of the transistor Q is connected to the DC core source B via the resistor R1, and the base is connected to one output of the control circuit 13.

The control circuit 13 is composed of an inverting amplifier that uses the output of the frequency converter circuit 3 as an inverting input, and has a gain corresponding to the ratio of the input resistance R6 and the feedback resistance R1.

A variable resistor R8 connected to the non-inverting input terminal is provided for offset adjustment.

In this +m example, the monostable multivibrator 2 and the control circuit 13 constitute a correction means for correcting the duty of the horizontal oscillation pulse.

By the way, if the frequency of the input horizontal synchronization signal 1g is approximately in the middle of the expected frequency range,
The output horizontal oscillation pulse of the horizontal oscillation circuit 2 and the output pulse of the monostable multivibrator 12 both have a duty of approximately 50%, and the on-time and off-time of the horizontal output transistor in the horizontal output circuit 5 are approximately 50%. equal.

Here, it is assumed that the frequency of the input horizontal synchronizing signal moves to the lower frequency side within a previously predicted frequency range. In this case, the output of the frequency/α pressure changing circuit 3 decreases compared to before, and naturally the negative polarity output of the control circuit 13 decreases while increasing its absolute value. As a result, the collector current of the transistor Q for varying the charging current in the monostable multivibrator 12 decreases, and the charging time of the capacitor C increases.

As a result, as shown in Section 21 or 'E5, even though the duty of the output of the horizontal oscillation circuit 2 is considerably less than 50%, the output of the monostable multivibrator 2, that is, the corrected horizontal The duty of the oscillation pulse is kept at approximately 50%.

Therefore, the on-time of the horizontal output transistor in the horizontal output circuit 5 is
is equal to the off-time, which causes the horizontal output circuit 5 to
Situations such as insufficient driving or stopping of driving can be avoided.

On the other hand, if the frequency of the input horizontal synchronization signal moves to the high frequency side within the pre-predicted frequency range, the output of the frequency/voltage conversion circuit 3 will increase compared to before, and naturally the output of the control circuit 13 will increase. also increases in the negative direction. For this reason, the collector DC current of the transistor Q8 for varying the charge I and α currents in the monostable multivibrator j2 increases, and the charging time of the capacitor C is shortened. As a result, although the duty of the output of the horizontal oscillation circuit 2 considerably exceeds 50%, the output duty of the monostable multivibrator is kept within about 50%. Therefore, the on time and off time of the horizontal output transistor in the horizontal output circuit 5 are almost equal, and it is possible to prevent problems such as the deflection being disturbed due to the accumulated charge effect due to the large on time as in the conventional case. .

In this way, the deflection circuit 11 changes the duty of the output water pulse of the horizontal oscillation circuit 2, which changes according to the frequency of the input horizontal synchronizing signal, to the monostable multivibrator 12.
By changing the pulse width of the horizontal oscillation pulse in accordance with the frequency of the horizontal synchronizing signal using the correction means consisting of the control wholesale circuit 13, the deflection output condition and the drive condition are sufficiently satisfied. When a synchronizing signal is input, the on-time of the horizontal output transistor in the horizontal output circuit 2 is prevented from decreasing, and insufficient driving of the horizontal output circuit 2 is eliminated. When a high-frequency horizontal synchronizing signal is input, ,
It is possible to prevent the on-time of the horizontal output transistor from increasing and eliminate disturbances in deflection due to the accumulated charge effect.

〔Effect of the invention〕

As explained above, according to the present invention, the duty of the output horizontal oscillation pulse of the horizontal oscillation circuit, which changes according to the frequency of the input horizontal synchronization signal, is adjusted according to the frequency of the horizontal synchronization signal. By changing the width, the configuration satisfies the deflection output conditions and drive conditions, so when a low frequency horizontal synchronization signal is input,
Prevents the on-time of the horizontal output transistor in the horizontal output circuit from decreasing, eliminating insufficient drive of the horizontal output circuit, and prevents the on-time of the horizontal output transistor from increasing when a high-frequency horizontal synchronization signal is input. This provides excellent effects such as being able to eliminate deflection disturbances caused by accumulated charge effects.

[Brief explanation of drawings]

1.2 is a circuit configuration diagram and a signal waveform diagram of each part of the circuit, respectively, showing an embodiment of the deflection circuit of the present invention, and FIG. 3 is a circuit configuration diagram showing an example of a conventional deflection circuit. 2...Horizontal oscillation circuit, 5...Horizontal output circuit, 11.
... Deflection circuit, 12... Monostable multivibrator,
13...Control circuit.

Claims (1)

[Claims] A horizontal oscillation circuit that outputs horizontal oscillation pulses with different duties depending on the frequency of the input horizontal synchronization signal, and a horizontal oscillation circuit provided between the horizontal oscillation circuit and the horizontal output circuit, A deflection circuit provided with a correction means that changes the pulse width of a pulse and performs correction to sufficiently satisfy deflection output conditions and drive conditions.