JP3447636B2 - Circuit and method for shaping vertical sync signal with crosstalk - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosstalk vertical sync signal waveform shaping circuit and method, and more particularly to a crosstalk vertical sync signal waveform shaping circuit for preventing the vertical sync signal from becoming unrecognizable due to crosstalk. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, when a signal is input to a video display device such as a liquid crystal projector, a long cable (for example, MIN D-sub) is used without using a BNC (coaxial) cable.
Etc.) causes crosstalk between signals.

Due to this crosstalk, the vertical synchronizing signal cannot be recognized on the circuit side, and it may be determined that there is no signal. A circuit for shaping the waveform is required to eliminate this malfunction. By performing the waveform shaping, it is possible to display even a signal having crosstalk.

[0004]

The first problem of the above-mentioned conventional crosstalk is that crosstalk occurs between signals when a long cable is used.

The reason is that no BNC (coaxial) cable is used.

A second problem is that the vertical synchronization signal cannot be recognized on the circuit side due to crosstalk, and it is determined that there is no signal.

The reason is that there is no circuit for waveform shaping.

[0008]

SUMMARY OF THE INVENTION A crosstalk vertical sync signal waveform shaping circuit according to the present invention comprises an amplitude detection circuit for producing a comparison voltage from a proportional portion of an amplitude, an effective value or an average value of a horizontal sync signal, and a vertical sync signal. An integration circuit that integrates the signal, a comparator that compares the comparison voltage generated by the amplitude detection circuit and the amplitude of the vertical synchronization signal integrated by the integration circuit, and shapes the waveform of the vertical synchronization signal, and a waveform that is shaped by the horizontal synchronization signal and the comparator. And a synchronization processing circuit for achieving phase synchronization with the generated vertical synchronization signal.

Further, a comparison voltage is produced from the proportional portion of the amplitude, effective value or average value of the horizontal synchronizing signal, the vertical synchronizing signal is integrated, and the produced comparison voltage and the amplitude of the integrated vertical synchronizing signal are compared and the vertical voltage is calculated. It is configured by a method of shaping the waveform of a vertical synchronizing signal which has been cross-talked by performing waveform shaping of the synchronizing signal so as to achieve phase synchronization between the horizontal synchronizing signal and the vertical synchronizing signal whose waveform has been shaped.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a waveform shaping circuit and method of a crosstalk vertical synchronizing signal of the present invention.

The waveform of the vertical sync signal which is cross-talking is shaped by detecting the amplitude of the horizontal sync signal, and malfunctions in subsequent circuits are eliminated.

The crosstalk as used herein means that the waveform of the horizontal synchronizing signal jumps into the vertical synchronizing signal by using a long cable or the like.

The reason why the comparison voltage Vo is generated from the horizontal synchronizing signal is that the duty cycle (pulse width / 1 cycle) is large, so that the amplitude can be easily detected.

This is also because when the sync signal is a composite sync signal (a mixture of the vertical sync signal and the horizontal sync signal), the signal is input through the signal line of the horizontal sync signal.

In this case, if the comparison voltage is to be generated from the vertical synchronization signal, the comparison voltage is generated from the waveform (noise component) that is crosstalking because no signal is input to the vertical synchronization signal. In this case, the waveform of the noise component is shaped and a malfunction occurs.

Referring to FIG. 1, according to the embodiment of the present invention, a horizontal sync signal amplitude detection circuit 1, a comparator 2 used for waveform shaping of a vertical sync signal, and a horizontal sync signal and a vertical sync waveform-shaped. A synchronization processing circuit 3 for processing signal synchronization is provided to prevent malfunction due to crosstalk.

By using them in a video display device such as a liquid crystal projector, malfunction does not occur even if crosstalk occurs using a long cable.

Next, the operation of the embodiment of the present invention will be described in detail with reference to FIG.

FIG. 2 is a waveform diagram showing the operation of an embodiment of the waveform shaping circuit and method of the crosstalk vertical synchronizing signal of the present invention.

When the horizontal synchronizing signal shown in FIG. 2A is input, the amplitude detecting circuit 1 of FIG. 1 detects the amplitude Vh of the horizontal synchronizing signal. From the detected amplitude Vh to the comparison voltage Vo
(Here, Vo = Vh / 2). Comparison voltage Vo
The method for producing is created as a proportional amount of the amplitude value indicating the magnitude of the amplitude of the horizontal synchronizing signal, a proportional amount of the effective value of the horizontal synchronizing signal, or a proportional amount of the average value of the horizontal synchronizing signal.

FIG. 2B shows the waveform of the vertical synchronizing signal which is crosstalked by the horizontal synchronizing signal. The vertical synchronizing signal and the comparison voltage Vo are input to the comparator 2, and the waveform is shaped as shown in FIG. By inputting the waveform-shaped vertical synchronization signal to the synchronization processing circuit 3, malfunction due to crosstalk can be prevented.

A slight delay occurs when the vertical synchronizing signal passes through the comparator 2, but since the delay is constant, it can be corrected by a circuit in the subsequent stage, particularly by the synchronization processing circuit 3 or the like. By correcting with the synchronization processing circuit 3,
The horizontal synchronizing signal and the vertical synchronizing signal can be phase-synchronized.

Next, a second embodiment of the present invention will be described in detail with reference to FIG.

FIG. 3 is a block diagram showing a second embodiment of a waveform shaping circuit and method of a crosstalk vertical synchronizing signal of the present invention.

In the above-described embodiment of the present invention, if the level of the horizontal sync signal causing crosstalk becomes higher than the comparison voltage Vo, it becomes impossible to prevent malfunction. Therefore, it is effective to add an integrating circuit 4 as shown in FIG. 3 because it is possible to attenuate the steep waveform of the horizontal synchronizing signal that is crosstalking.

[0027]

As described above, according to the waveform shaping circuit and method of the vertical sync signal having crosstalk according to the present invention, the first effect is that the malfunction of the vertical sync signal due to crosstalk can be prevented.

The reason is that the amplitude of the horizontal synchronizing signal is detected by the amplitude detecting circuit, a comparison voltage is generated from the detected amplitude, the comparison voltage and the vertical synchronizing signal are input to the comparator, and the waveform of the vertical synchronizing signal is waveformd. This is because it is shaped.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a waveform shaping circuit and method of a crosstalk vertical synchronizing signal of the present invention.

FIG. 2 is a waveform diagram showing an operation of an embodiment of a waveform shaping circuit and method of a crosstalk vertical synchronizing signal of the present invention.

FIG. 3 is a configuration diagram showing a second embodiment of a waveform shaping circuit and method of a crosstalk vertical synchronizing signal of the present invention.

[Explanation of symbols]

1 Amplitude detection circuit 2 comparator 3 Synchronous processing circuit 4 integrating circuit

Claims (12)

(57) [Claims] 1. An amplitude detection circuit for producing a comparison voltage from the amplitude of a horizontal synchronization signal, a comparator for comparing the amplitude of a comparison voltage produced by the amplitude detection circuit with the amplitude of a vertical synchronization signal, and shaping the waveform of the vertical synchronization signal, and a horizontal synchronization circuit. A waveform shaping circuit for a crosstalk vertical synchronizing signal, comprising: a synchronization processing circuit for synchronizing the phase of the signal and the vertical synchronizing signal waveform-shaped by the comparator. 2. An amplitude detection circuit for producing a comparison voltage from a proportional portion of the effective value of the horizontal synchronization signal, and a comparator for comparing the amplitude of the comparison voltage produced by the amplitude detection circuit with the amplitude of the vertical synchronization signal to shape the waveform of the vertical synchronization signal. A waveform shaping circuit for a cross-talk vertical synchronizing signal, comprising: a synchronization processing circuit that synchronizes the phase of the horizontal synchronizing signal and the vertical synchronizing signal whose waveform is shaped by a comparator. 3. An amplitude detection circuit for producing a comparison voltage from a proportional portion of an average value of the horizontal synchronization signal, and a comparator for comparing the amplitude of the vertical synchronization signal with the comparison voltage produced by the amplitude detection circuit to shape the waveform of the vertical synchronization signal. A waveform shaping circuit for a cross-talk vertical synchronizing signal, comprising: a synchronization processing circuit that synchronizes the phase of the horizontal synchronizing signal and the vertical synchronizing signal whose waveform is shaped by a comparator. 4. An amplitude detection circuit for generating a comparison voltage from the amplitude of the horizontal synchronization signal, an integration circuit for integrating the vertical synchronization signal, and a comparison voltage generated by the amplitude detection circuit and a vertical synchronization signal integrated by the integration circuit. A crosstalk vertical synchronizing signal characterized by comprising a comparator for comparing amplitudes and shaping the waveform of the vertical synchronizing signal, and a synchronization processing circuit for performing phase synchronization between the horizontal synchronizing signal and the vertical synchronizing signal waveform shaped by the comparator. Waveform shaping circuit. 5. An amplitude detection circuit for producing a comparison voltage from a proportional portion of an effective value of a horizontal synchronization signal, an integration circuit for integrating a vertical synchronization signal, and a comparison voltage produced by the amplitude detection circuit and a vertical integrated by the integration circuit. Crosstalk characterized by comprising a comparator for comparing the amplitudes of synchronization signals and shaping the waveform of the vertical synchronization signal, and a synchronization processing circuit for phase synchronization of the horizontal synchronization signal and the vertical synchronization signal waveform-shaped by the comparator Vertical sync signal waveform shaping circuit. 6. An amplitude detection circuit for producing a comparison voltage from a proportional portion of an average value of a horizontal synchronization signal, an integration circuit for integrating a vertical synchronization signal, and a comparison voltage produced by the amplitude detection circuit and a vertical integrated by the integration circuit. Crosstalk characterized by comprising a comparator for comparing the amplitudes of synchronization signals and shaping the waveform of the vertical synchronization signal, and a synchronization processing circuit for phase synchronization of the horizontal synchronization signal and the vertical synchronization signal waveform-shaped by the comparator Vertical sync signal waveform shaping circuit. 7. A comparison voltage is generated from the amplitude of the horizontal synchronizing signal, the generated comparison voltage is compared with the amplitude of the vertical synchronizing signal, the vertical synchronizing signal is waveform-shaped, and the horizontal synchronizing signal and the waveform-shaped vertical synchronizing signal are compared. A method for shaping the waveform of a vertical sync signal with crosstalk, characterized in that the phase synchronization is obtained. 8. A comparison voltage is generated from the proportional portion of the effective value of the horizontal synchronizing signal, the generated comparison voltage is compared with the amplitude of the vertical synchronizing signal, the vertical synchronizing signal is waveform shaped, and the horizontal synchronizing signal and the waveform shaped vertical are compared. A waveform shaping method for a cross-talk vertical synchronizing signal, characterized in that phase synchronization with the synchronizing signal is achieved. 9. A comparison voltage is generated from a proportional portion of an average value of the horizontal synchronizing signal, the generated comparison voltage is compared with the amplitude of the vertical synchronizing signal, the vertical synchronizing signal is waveform shaped, and the horizontal synchronizing signal and the waveform shaped vertical are compared. A waveform shaping method for a cross-talk vertical synchronizing signal, characterized in that phase synchronization with the synchronizing signal is achieved. 10. A horizontal synchronizing signal is generated by generating a comparison voltage from the amplitude of the horizontal synchronizing signal, integrating the vertical synchronizing signal, comparing the generated comparison voltage with the amplitude of the integrated vertical synchronizing signal, and shaping the waveform of the vertical synchronizing signal. A waveform shaping method for a cross-talk vertical synchronizing signal, characterized in that a phase synchronization between the signal and the waveform shaped vertical synchronizing signal is achieved. 11. A comparison voltage is generated from a proportional portion of an effective value of a horizontal synchronization signal, a vertical synchronization signal is integrated, the generated comparison voltage and the amplitude of the integrated vertical synchronization signal are compared, and the waveform of the vertical synchronization signal is shaped. , A method of shaping a waveform of a cross-talked vertical synchronizing signal, characterized in that phase synchronization between a horizontal synchronizing signal and a waveform shaped vertical synchronizing signal is achieved. 12. A comparison voltage is generated from a proportional portion of an average value of the horizontal synchronization signal, the vertical synchronization signal is integrated, the generated comparison voltage and the amplitude of the integrated vertical synchronization signal are compared, and the waveform of the vertical synchronization signal is shaped. , A method of shaping a waveform of a cross-talked vertical synchronizing signal, characterized in that phase synchronization between a horizontal synchronizing signal and a waveform shaped vertical synchronizing signal is achieved.