JPH0346829B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deflection circuit that can also accommodate synchronous signal input of non-standard frequencies.

[Conventional technology]

With the spread of personal computers,
Many television receivers that also function as RGB displays have become known. However, some RGB outputs of personal computers have a horizontal synchronization frequency of 15.75kHz, which is the standard frequency, and others, which aim for high resolution, at 24.83kHz.
It becomes necessary to switch the horizontal oscillation frequency within the television receiver.

The conventional deflection circuit 1 shown in FIG. 3 converts the frequency and voltage of a synchronizing signal sent from an externally connected device such as a personal computer using a frequency/voltage conversion circuit 2, converting the high frequency components of the converted output into low frequency components. The signal removed by the wave circuit 3 is sent to the horizontal oscillation circuit 4.
supply to. The oscillation frequency of the horizontal oscillation circuit 4 is controlled to be constant by an automatic frequency control circuit 5, and its horizontal oscillation output is supplied to a horizontal output circuit 7 via a horizontal drive circuit 6. The horizontal output pulse obtained from the horizontal output circuit 7 is fed back to the automatic frequency control circuit 5, and is used to control the oscillation frequency of the horizontal oscillation circuit 4 by comparing the phase with the horizontal synchronizing signal.

8 is a mode discrimination circuit, and a low frequency circuit 3
Determine whether the deflection mode is standard mode or high resolution mode according to the output of
According to the determination result, the circuit constants of the horizontal output circuit 7 are changed.

[Problem that the invention seeks to solve]

The conventional deflection circuit 1 described above has no problem when the synchronization signal input is at a standard frequency, or when the externally connected device is a personal computer that outputs horizontal and vertical synchronization signals separately, but when the synchronization signal is input at a non-standard frequency, there is no problem. If a composite synchronization signal in which the horizontal synchronization signal is combined with the vertical synchronization signal is input, when the phase of the horizontal synchronization signal is shifted during horizontal position adjustment, the phase of the vertical synchronization signal will also shift, resulting in vertical position deviation. There were problems such as vertical synchronization may be disrupted.

[Means for solving problems]

This invention solves the above problem, and includes inputting a horizontal synchronizing signal of a standard frequency or a frequency other than this, so that the horizontal output pulse of the horizontal output circuit matches the phase of the horizontal synchronizing signal input. The automatic frequency control circuit is a deflection circuit that controls the oscillation frequency of a horizontal oscillation circuit, and when the horizontal synchronization signal input is not a standard frequency, the automatic frequency control circuit is interposed between the horizontal output circuit and the automatic frequency control circuit, and when the horizontal synchronization signal input is not a standard frequency, the horizontal output pulse is The gist of the present invention is that it is constructed by providing a delay circuit that delays the delay time, and a horizontal position adjustment means that adjusts the horizontal position by varying the amount of delay in this delay circuit.

[Effect]

This invention changes the phase of the horizontal synchronizing signal by varying the amount of delay of the horizontal output pulse in a delay circuit provided between the horizontal output circuit and the automatic frequency control circuit in response to the horizontal synchronizing signal input having a frequency different from the standard frequency. The horizontal position can be adjusted without shifting.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. 1 and 2 are 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.

In FIG. 1, the deflection circuit 11 has a horizontal position adjustment circuit 12 provided between the horizontal output circuit 7 and the automatic frequency control circuit 4. Horizontal position adjustment circuit 12
The delay circuit 12a delays the horizontal output pulse from the horizontal output circuit 7, and selectively switches between the delayed horizontal output pulse that is the output of the delay circuit 12a and the non-delayed horizontal output pulse from the horizontal output circuit 7. It consists of a switching circuit 12b that outputs.

The delay circuit 12a includes first and second monostable multivibrators 13, 14 and a waveform shaping circuit 15.
are connected in series between the horizontal output circuit 7 and the switching circuit 12b, and the first and second time constant switching circuits 13a and 14a are connected to the first and second monostable multivibrators 13 and 14. It has a configuration that is as follows. The first and second monostable multivibrators 13 and 14 have similar configurations, and have a NOR gate circuit 1 having a trigger input terminal and a feedback input terminal.
The output terminal of the NOR gate circuit 17 is connected to both input terminals of the NOR gate circuit 17 via an integrating capacitor _C0 , and the output terminal of the NOR gate circuit 17 in the subsequent stage is connected to the feedback input terminal of the NOR gate circuit 16 in the previous stage. First monostable multivibrator 1
The trigger input of No. 3 is the horizontal output pulse from the horizontal output circuit 7, and the trigger input of the second monostable multivibrator 14 is the output of the NOR gate circuit 16 of the first monostable multivibrator 13.

The first time constant switching circuit 13a is a resistor connected between the signal line connecting the integrating capacitor C ₀ and the input terminal of the subsequent NOR gate circuit 17 and the power supply +B.
This is a parallel connection circuit of R ₁ and R ₂ , and one resistor R ₂ is
It is selectively closed by a switch S which is opened and closed by the output of the mode discrimination circuit 8. Further, the second time constant switching circuit 14a includes a variable resistor _Rv provided between the signal line connecting the integrating capacitor _C0 and the input terminal of the subsequent NOR gate circuit 17 and the power supply +B.

The waveform shaping circuit 15 includes a differential capacitor _C1 that differentiates the output of the NOR gate circuit 16 in the second monostable multivibrator 14, and a differential capacitor _C1.
It consists of a NAND gate circuit 18 that inverts the output of.

The switching circuit 12b selects either the horizontal output circuit 7 or the delay circuit 12a depending on the output of the mode discrimination circuit 8.
A changeover switch 19 selectively connects the frequency control circuit 5 to the automatic frequency control circuit 5.

Here, when the synchronization signal input is a standard frequency horizontal synchronization signal, all outputs of the mode discrimination circuit 8 are at low level. Therefore, the changeover switch 19 is in a state switched to the horizontal output circuit 7 side, and as a result, no delay is performed by the delay circuit 12a, and normal automatic frequency control is performed in which the phase of the input synchronization signal and the horizontal output pulse match. will be held.

On the other hand, when the synchronization signal input is a horizontal synchronization signal with a non-standard frequency, all outputs of the mode discrimination circuit 8 become high level, and the changeover switch 19 is switched to the delay circuit 12a side. Also,
At the same time, the switch S is closed and the time constant of the first monostable multivibrator 13 is switched to the short time side. Therefore, the horizontal output pulse supplied to the delay circuit 12a is transmitted to the first monostable multivibrator 13 as shown in FIGS.
The second monostable multivibrator 14 delays ΔT for ₁ hour and the second monostable multivibrator 14 for ΔT ₂ hours, and then undergoes waveform processing in the waveform shaping circuit 15 as shown in D and E of the same figure. The signal is fed back to the automatic frequency control circuit 4 with a delay of ΔT ₁ +ΔT ₂ hours.

That is, the automatic frequency control circuit 4 performs automatic frequency control while allowing a phase shift between the input horizontal synchronizing signal and the horizontal output pulse.

Therefore, by varying the resistance value of the variable resistor R _v of the second time constant switching circuit 14a, it is possible to change the delay time in the delay circuit 12a and freely adjust the horizontal position. Of course, since the phase of the horizontal synchronizing signal itself is not changed, it goes without saying that it is possible to handle a composite synchronizing signal of a non-standard frequency in which horizontal and vertical synchronizing signals are combined.

Note that when the synchronization signal input is a horizontal synchronization signal with a non-standard frequency different from the above, the signal for the switch S among the outputs of the mode discrimination circuit 8 is at a low level, and the signal for the first monostable multivibrator 13 is at a low level. The time constant is switched to the long time side. As a result, the horizontal output pulse supplied to the delay circuit 12a is delayed by the first monostable multivibrator 13 for ΔT _1a time, and by the second monostable multivibrator 14 for ΔT ₂ hours,
In total, the feedback is fed back to the automatic frequency control circuit 4 with a delay of ΔT _1a +ΔT ₂ hours.

In this manner, the deflection circuit 11 adjusts the amount of delay of the horizontal output pulse in the delay circuit 12a provided between the horizontal output circuit 7 and the automatic frequency control circuit 5 in response to the horizontal synchronizing signal input having a frequency different from the standard frequency. Since the horizontal position can be adjusted by changing the horizontal position, by shifting the phase of the horizontal output pulse without shifting the phase of the horizontal synchronization signal,
The horizontal position can be adjusted, so it can handle composite synchronization signals that are horizontal and vertical without disturbing the vertical synchronization, and it can also handle delayed horizontal output pulses and non-delayed horizontal output pulses. Since the pulse can be changed according to the input horizontal synchronizing signal, it is possible to correspond to the horizontal synchronizing signal of standard frequency.

〔Effect of the invention〕

As explained above, according to the present invention, the delay amount of the horizontal output pulse can be varied in the delay circuit provided between the horizontal output circuit and the automatic frequency control circuit in response to the horizontal synchronization signal input having a frequency different from the standard frequency. This makes it possible to adjust the horizontal position without shifting the phase of the horizontal synchronization signal.
By shifting the phase of the horizontal output pulse, the horizontal position can be adjusted, and therefore, it is possible to respond to a composite synchronization signal that is a combination of horizontal and vertical signals without disturbing the vertical synchronization. In addition, delayed horizontal output pulses and non-delayed horizontal output pulses are
Since it is possible to switch according to the horizontal synchronization signal input, it has excellent effects such as being able to correspond to horizontal synchronization signals of standard frequencies.

[Brief explanation of drawings]

1 and 2 are circuit configuration diagrams and signal waveform diagrams of various parts 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. 11...Deflection circuit, 4...Horizontal oscillation circuit, 5...
...Automatic frequency control circuit, 7...Horizontal output circuit, 1
2...Horizontal position adjustment circuit, 12a...Delay circuit.

Claims (1)

[Claims] 1. A horizontal synchronization signal of a standard frequency or a frequency other than this is input, and an automatic frequency control circuit controls the oscillation frequency of the horizontal oscillation circuit so that the horizontal output pulse of the horizontal output circuit matches the phase of the horizontal synchronization signal input. a delay circuit interposed between the horizontal output circuit and the automatic frequency control circuit to delay a horizontal output pulse when the horizontal synchronizing signal input is not at a standard frequency; and a delay amount in this delay circuit. A deflection circuit comprising a horizontal position adjusting means for adjusting the horizontal position by varying the horizontal position.