JPH0689088A - Synchronizing signal polarity discriminating circuit - Google Patents

Abstract

PURPOSE:To provide the synchronizing signal polarity discrimination circuit with which the DC signals corresponding to the positive and negative polarities of a horizontal or vertical synchronizing signal are exactly obtainable even with a device which has a horizontal or vertical oscillation circuit and can receive a high horizontal scanning frequency and a device which can receive plural horizontal or vertical scanning frequencies. CONSTITUTION:The voltage value of the horizontal or vertical synchronizing signal 1 is stored in a D flip-flop circuit 4 or memory circuit 4, such as analog memory, by the rising or falling timing of the output pulse signal of the horizontal or vertical oscillation circuit 5 which automatically follows up the horizontal or vertical scanning frequencies and the DC signal obtainable at its output terminal is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a horizontal or vertical oscillating circuit such as a television, a display or a monitor, which can receive a high horizontal scanning frequency or a plurality of horizontal or vertical scanning frequencies. The present invention relates to a circuit for accurately obtaining a DC signal corresponding to positive or negative polarities of a sync signal and always obtaining a positive or negative horizontal or vertical sync signal regardless of the positive or negative polarities of a horizontal or vertical sync signal.

[0002]

2. Description of the Related Art A conventional sync signal polarity discriminating circuit consists of a monostable multivibrator and a resistor and a capacitor for a horizontal or vertical synchronizing signal, as described in the sync signal polarity discriminating circuit of Japanese Patent Laid-Open No. 64-44174. It is converted into a pulse signal of an arbitrary pulse width by a constant circuit, the voltage value of the horizontal or vertical synchronizing signal is stored in the D flip-flop circuit at the rising or falling timing of this pulse signal, and the positive or negative of the horizontal or vertical synchronizing signal is stored. A DC signal corresponding to the polarity is obtained.

Further, the exclusive OR of the horizontal or vertical synchronizing signal and the DC signal corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal is used to always make the positive polarity regardless of the positive or negative polarity of the horizontal or vertical synchronizing signal. Alternatively, a negative horizontal or vertical sync signal is obtained.

[0004]

In the above-described sync signal polarity discriminating circuit according to the prior art, a horizontal or vertical sync signal is converted into a pulse signal having an arbitrary pulse width by a monostable multivibrator and a time constant circuit composed of a resistor and a capacitor. The voltage value of the horizontal or vertical synchronizing signal is converted and stored in the D flip-flop circuit at the rising or falling timing of this pulse signal to obtain a DC signal corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal. Therefore, in a device capable of receiving a high horizontal scanning frequency, there are large variations and drifts in the pulse width due to the circuit elements used in the time constant circuit consisting of a monostable multivibrator and resistors and capacitors, and horizontal or vertical synchronization. Since the rising position or the falling position is different depending on the positive and negative polarities of the signal, there is a problem that a DC signal corresponding to the positive or negative polarities of the horizontal or vertical sync signal cannot be accurately obtained. In a device capable of receiving multiple horizontal or vertical scanning frequencies, a time constant circuit consisting of a monostable multivibrator and a resistor and capacitor is used to convert the pulse signal into an arbitrary pulse width. Therefore, there is a problem in that a DC signal corresponding to the positive or negative polarities of the horizontal or vertical sync signal cannot be accurately obtained.

An object of the present invention is to accurately detect a DC signal corresponding to the positive or negative polarity of a horizontal or vertical synchronizing signal even in a device capable of receiving a high horizontal scanning frequency and a device capable of receiving a plurality of horizontal or vertical scanning frequencies. And to provide a sync signal polarity discriminating circuit that can accurately obtain a horizontal or vertical sync signal that is always positive or negative by using this DC signal.

[0006]

The above-mentioned object is to determine the voltage value of a horizontal or vertical synchronizing signal at the rising or falling timing of the output pulse signal of the horizontal or vertical oscillation circuit that automatically follows the horizontal or vertical scanning frequency. D
This is achieved by storing in a storage circuit such as a flip-flop circuit or an analog memory and using a DC signal obtained at its output terminal.

[0007]

In the sync signal polarity discriminating circuit, the horizontal or vertical sync signal is input as a data signal of a storage circuit such as a D flip-flop circuit or an analog memory, and the horizontal or vertical scanning frequency is automatically followed. Alternatively, the output pulse signal of the vertical oscillation circuit is used as a timing signal for storing in a storage circuit such as a D flip-flop circuit or an analog memory, and the voltage value of the horizontal or vertical synchronizing signal is used as the D flip-flop circuit or the analog memory. The direct current signal corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal can be accurately obtained by storing it in the storage circuit.

[0008]

1 shows an embodiment of a sync signal polarity discriminating circuit to which the present invention is applied.

A signal obtained by amplifying the horizontal or vertical synchronizing signal 1 by the amplifier circuit 2 is a D flip-flop circuit (memory circuit) 4
Add to the data terminal of. Further, the output pulse signal 6 of the horizontal or vertical oscillation circuit 5 is applied to the clock terminal of the D flip-flop circuit (memory circuit) 4, and the horizontal or vertical synchronization signal 1 is amplified at the falling timing of the output pulse signal 6. The voltage value of the signal amplified in 2 is stored in the D flip-flop circuit (storage circuit) 4. At the output terminal of the D flip-flop circuit (storage circuit) 4, a DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal 1 when stored is obtained.

The DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical sync signal 1 and the horizontal or vertical sync signal 1
And the signal amplified by the amplifier circuit 2 with the exclusive OR gate 3
Exclusive OR gate 3 by adding to the input terminal of
The horizontal or vertical sync signal 7 with positive and negative polarities unified is always obtained at the output terminal of, and by adding the horizontal or vertical sync signal 7 with positive and negative polarities unified to the horizontal or vertical oscillator circuit 5, It is possible to obtain the output pulse signal 6 of the horizontal or vertical oscillation circuit 5 synchronized with the vertical synchronizing signal 1.

Therefore, the output pulse signal 6 of the horizontal or vertical oscillating circuit 5 automatically follows the horizontal or vertical synchronizing signal 1, and the polarity does not change, and High and Low within one cycle.
, The DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal 1 can be accurately obtained.

Next, each signal operation of the embodiment of FIG. 1 will be described in detail with reference to FIG.

The D flip-flop circuit (memory circuit) 4 in the range (a) when the horizontal or vertical synchronizing signal 1 has a positive polarity.
The contents stored in H are at the timing of the first falling edge of the output pulse signal 6 of the horizontal or vertical oscillation circuit 5.
It changes from Low to Low, and continues to be Low at the timing of the second and third falling edges. Further, the DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal 1 generated at the output terminal of the D flip-flop circuit (memory circuit) 4 also changes. By exclusive ORing the DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical sync signal 1 generated at the output terminal of the D flip-flop circuit (memory circuit) 4 and the horizontal or vertical sync signal 1, A pulse signal with the same polarity as the horizontal or vertical sync signal 1,
That is, a positive pulse signal is obtained.

The contents stored in the D flip-flop circuit (memory circuit) 4 in the range (b) when the horizontal or vertical synchronizing signal 1 has the negative polarity are the output pulse signal 6 of the horizontal or vertical oscillator circuit 5. It changes from Low to High at the timing of the first fall, and remains High at the timing of the second and third fall. Further, the DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal 1 generated at the output terminal of the D flip-flop circuit (memory circuit) 4 also changes. The exclusive OR of the DC signal 8 corresponding to the positive or negative polarity of the horizontal or vertical synchronizing signal 1 generated at the output terminal of the D flip-flop (memory circuit) 4 and the horizontal or vertical synchronizing signal 1 is used to determine the horizontal Alternatively, a pulse signal having a polarity opposite to that of the vertical synchronizing signal 1, that is, a positive polarity pulse signal is obtained.

Therefore, when a positive or negative polarity horizontal or vertical synchronizing signal 1 is input to this circuit, the exclusive OR output terminal has a unified horizontal or vertical synchronizing signal 7.
By adding the horizontal or vertical synchronizing signal 7 having the same polarity to the horizontal or vertical oscillating circuit 5, the output pulse signal 6 of the horizontal or vertical oscillating circuit 5 synchronized with the horizontal or vertical synchronizing signal 1 can be obtained. Obtainable.

[0016]

According to the present invention, in a device having a horizontal or vertical oscillation circuit and capable of receiving a high horizontal scanning frequency or a device capable of receiving a plurality of horizontal or vertical scanning frequencies, a horizontal or vertical synchronizing signal of A direct current signal corresponding to positive and negative polarities can be accurately obtained, and a positive or negative polarity horizontal or vertical synchronization signal is always obtained by exclusive ORing the direct current signal and the horizontal or vertical synchronization signal. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a sync signal polarity discriminating circuit to which the present invention is applied.

FIG. 2 is a diagram showing respective signal operation waveforms of an embodiment of a sync signal polarity discriminating circuit to which the present invention is applied.

[Explanation of symbols]

1 ... Horizontal or vertical synchronizing signal, 2 ... Amplifying circuit, 3 ... Exclusive OR gate, 4 ... D flip-flop (memory circuit), 5 ... Horizontal or vertical oscillating circuit, 6 ... Output pulse signal, 7 ... Unified polarity Horizontal or vertical sync signal, 8 ... High or L corresponding to positive and negative polarities of the sync signal
ow DC signal, 9 ... Transistor.

Claims (2)

[Claims] 1. A voltage value of a horizontal or vertical synchronizing signal is stored in a storage circuit such as a D flip-flop circuit or an analog memory at the rising or falling timing of an output pulse signal of the horizontal or vertical oscillation circuit, and the horizontal or vertical synchronization signal is stored. A sync signal polarity discriminating circuit, characterized in that a DC signal corresponding to positive or negative polarities of the sync signal is obtained. 2. A horizontal or vertical synchronizing signal and a DC signal corresponding to positive or negative polarities of the horizontal or vertical synchronizing signal,
2. The synchronization according to claim 1, further comprising an exclusive OR gate circuit or the like for always generating a positive or negative horizontal or vertical synchronizing signal regardless of the positive or negative polarity of the horizontal or vertical synchronizing signal. Signal polarity determination circuit.