JPH0250651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulse conversion circuit, and particularly to a pulse conversion circuit that inverts the polarity of a synchronizing signal.

[Conventional technology]

For example, in a television receiver that receives broadcast radio waves, a synchronization signal is extracted from the received signal, and the synchronization signal is used to perform various video processing. The polarity of such a synchronization signal was fixed and not arbitrary. However, in recent television games, display monitors, and the like, unique synchronization signals are generated internally, and the synchronization signals are used to perform various signal processing. The polarity of such a synchronization signal is not determined, and a synchronization signal with a polarity suitable for each device is generated. Therefore, in order to use such a synchronization signal of undetermined polarity in other devices, it is necessary to provide a conversion circuit to obtain the required polarity.

[Problem that the invention seeks to solve]

However, if a conversion circuit for converting a synchronization signal whose polarity is not determined is attached to each device, there will be no versatility, the number of models will increase, and the cost will also increase.

Therefore, the main object of the present invention is to provide a pulse conversion circuit that can derive pulse signals of the same polarity regardless of the polarity of the input pulse signals.

[Means for solving problems]

The pulse conversion circuit according to the present invention inverts the polarity of the pulse signal by the polarity reversing means, generates a voltage from the first voltage generating means according to the polarity of the pulse signal applied to the input of the polarity reversing means, and , a voltage corresponding to the output of the polarity reversing means is generated from the second voltage generating means. Then, the pulse switching means is switched according to the respective outputs of the first and second voltage generating means, and a pulse signal is applied to the input of the polarity reversing means in response to application of a voltage according to the first polarity. The device is configured to derive a pulse signal whose polarity is inverted in response to application of a voltage corresponding to the output of the polarity inverting means.

[Effect]

The pulse conversion circuit according to the present invention derives a pulse signal whose polarity is not inverted if the polarity of the pulse signal is the first polarity, and derives a pulse signal whose polarity is inverted if the polarity of the pulse signal is the second polarity. Therefore, pulse signals of the same polarity can be derived regardless of the polarity of the input pulse signals.

[Embodiments of the invention]

FIG. 1 is an electrical circuit diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of FIG. 1.

The pulse conversion circuit shown in FIG.
A waveform shaping circuit 1 that shapes the waveform of the synchronization signal given to a, a polarity inversion circuit 2 that inverts the polarity of the synchronization signal shaped by the waveform shaping circuit 1, and a voltage according to the polarity of the output of the waveform shaping circuit 1. a first voltage generation circuit 3a that generates a voltage, and a second voltage generation circuit 3b that generates a voltage according to the output of the polarity inversion circuit 2;
It includes a pulse switching circuit 4 that derives a negative polarity synchronization signal regardless of the polarity of the synchronization signal applied to the input terminal 1a.

First, when a positive synchronization signal is applied to the input terminal 1a, it is applied to the base of the transistor 13 via the resistor 11 and the capacitor 12. A bias voltage is applied to the base of the transistor 13 by dividing the power supply voltage +Vcc by resistors 14 and 15. When the transistor 13 receives the positive synchronization signal, it generates a negative synchronization signal across the resistor 16 connected to its collector. This synchronizing signal inverted to negative polarity is applied to the polarity inverting circuit 2, and is applied to the base of the transistor 23 via the resistor 21 and the capacitor 22. Therefore, a synchronizing signal inverted to the original positive polarity is derived to the collector of the transistor 23. This positive synchronization signal is applied to the base of a transistor 44 included in the pulse switching circuit 4.

On the other hand, the negative polarity synchronization signal whose waveform has been shaped and whose polarity has been inverted by the waveform shaping circuit 1 is given to the first voltage generation circuit 3a. This negative synchronization signal charges the capacitor 32a via the resistor 31a. As shown in FIG. 2a, this negative polarity synchronization signal has a long high level period, so the voltage generated across the capacitor 32a is a high level voltage.
Become a V _P. This voltage V _P is applied to the base of a transistor 43 via a resistor 41 and a backflow prevention diode 42 included in the pulse switching circuit 4 . Therefore, transistor 43 becomes conductive and its collector becomes low level. Since the collector of transistor 43 is connected to the base of transistor 44 via diode 45, transistor 44 becomes non-conductive.

On the other hand, when a pulse of positive polarity is derived from the polarity inversion circuit 2, the second voltage generation circuit 3b operates through a resistor 31 in the same manner as the first voltage generation circuit 3a described above.
In order to charge the capacitor 32b through the capacitor 32b, a low level voltage _VN as shown in FIG. 2b is generated. However, as described above, when the high-level voltage V _P is generated from the first voltage generating circuit 3a, the transistor 43 becomes conductive, so the second voltage generating circuit 3a becomes conductive.
The output of the voltage generating circuit 3b is forced to the ground potential. The ground potential voltage generated from the second voltage generating circuit 3b is applied to a resistor 51 and a diode 52.
is applied to the base of the transistor 53 through the transistor 53, so the transistor 53 becomes non-conductive. The collector of transistor 53 is connected to the base of transistor 56 via a reverse current prevention diode 58.

When a positive synchronization signal is applied to the input terminal 1a, the first voltage generating circuit 3a generates a voltage V _P to make the transistor 43 conductive. At this time, since the output terminal of the polarity inverting circuit 2 is grounded via the transistor 43, the second voltage generating circuit 3b generates a low level voltage (ground potential), so that the transistor 53 becomes non-conductive. Therefore, transistor 56 becomes conductive and a negative synchronization signal is generated.

On the other hand, when a negative synchronization signal is applied to the input terminal 1a, the first voltage generating circuit 3a generates the voltage _VN , so that the transistor 43 becomes non-conductive and the transistor 44 becomes conductive. At this time, since the second voltage generation circuit 3b generates the voltage V _P based on the negative polarity synchronization signal output from the polarity inversion circuit 2,
Transistor 53 becomes conductive. Therefore, transistor 56 becomes non-conductive. When the transistor 44 becomes conductive, a negative polarity synchronization signal of the output of the polarity inverting circuit 2 is derived from its collector.

Note that in the embodiment shown in FIG. 1 described above, a synchronization signal of negative polarity is derived based on a synchronization signal of positive polarity or negative polarity, but it is possible to generate a synchronization signal of positive polarity conversely. It may be configured as follows.

〔Effect of the invention〕

As described above, according to the present invention, the polarity of the input synchronization signal is determined, and if the synchronization signal has the required polarity, it is derived as is, and if the synchronization signal has the opposite polarity, the polarity inversion circuit is used. Since an inverted synchronization signal is derived, a synchronization signal with the same polarity can be obtained regardless of the polarity of the input synchronization signal.

[Brief explanation of drawings]

FIG. 1 is a specific electrical circuit diagram of one embodiment of the present invention. FIG. 2 is a waveform diagram for explaining the operation of FIG. 1. In the figure, 1 is a waveform shaping circuit, 2 is a polarity inversion circuit, 3a is a first voltage generation circuit, 3b is a second voltage generation circuit, 4 is a pulse switching circuit, 43, 44
indicates a transistor constituting the first switching means, and 53, 55, and 56 indicate transistors constituting the second switching means.

Claims (1)

[Scope of Claims] 1. A pulse conversion circuit that derives a pulse signal having a first or second polarity as a pulse signal of the same polarity, comprising: a polarity inversion means for inverting the polarity of the pulse signal; the polarity inversion means a first voltage generating means for generating a voltage according to the polarity of the pulse signal applied to the input of the second voltage generating means; a second voltage generating means for generating a voltage according to the polarity of the output of the polarity reversing means; Deriving a pulse signal to be applied to the input of the polarity reversing means in response to application of a voltage according to the first polarity from the voltage generating means, A pulse conversion circuit comprising pulse switching means for deriving a pulse signal whose polarity is inverted from an output of the polarity inverting means in response to application of a voltage corresponding to the polarity inverting means. 2. The pulse switching means derives a pulse signal to be applied to the input of the polarity reversing means in response to application of a voltage according to the first polarity from the first voltage generating means. switching means; a second switching means for deriving a pulse signal whose polarity is inverted from the output of the polarity reversing means in response to application of a voltage according to the second polarity from the second voltage generating means; The pulse conversion circuit according to claim 1, comprising: