JPS6016722A - Waveform shaping device - Google Patents

Abstract

PURPOSE:To attain the waveform shaping of a synchronizing signal by providing a rectifier so as to change the comparison level in response to the level change in the input television synchronizing signal. CONSTITUTION:The television synchronizing signal fed to a terminal 1 is amplified by an amplifier 2 and applied to one input terminal of a comparator 3 and rectifier 6. The rectifier 6 has a rectifying function to detect and hold the peak value of this synchronizing signal and a function to control the range of change in the rectified output signal and the DC bias. That is, the DC voltage changed in response to the level change in this synchronizing signal is obtained. Thus, when the level of this synchronizing signal is changed from (a) to a', the comparison signal is set so as to be changed from (b) to b'. Thus, the pulse width change and phase change due to the synchronizing signal and level change are less at an output terminal 5 as shown in (c) and the waveform shaping is conducted accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waveform shaping device for shaping the waveform of a television synchronization signal, and an object thereof is to enable accurate waveform shaping of the synchronization signal.

Conventionally, this type of device supplies a television synchronizing signal supplied from an input terminal 1 to one input terminal of a comparator 3 via an amplifier 2, as shown in FIG. A comparison signal was supplied from the comparator 3 to the other input terminal of the comparator 3, and a waveform-shaped television synchronization signal was output from the output terminal 6. However, the level of the television synchronization signal whose waveform is folded is not necessarily constant. For example, when the level of a television synchronization signal with a slope as shown in Figure 2a changes from a to a', this television synchronization signal is constantly compared with a constant voltage such as b, and the pulse is detected. When waveform shaping is performed, pulse width changes and phase changes occur as shown in C, and in extreme cases, the output signal may disappear.

The present invention eliminates the above-mentioned drawbacks and will be described below along with examples thereof. 1.2, 3.6 in Figure 3
correspond to the same reference numerals shown in FIG. 6
is a rectifier that has a rectification function that detects and holds the peak value of a television synchronization signal, and a function that controls the change range and DC bias of the rectified output signal.

FIG. 4 shows the specific configuration of the rectifier 6, where 7 is an input terminal, 8 is a compensating capacitor, 9.1o is a rectifying diode, 11 is a smoothing capacitor, and 12 is a rectifying diode.
．． 13 is a variable resistor, and 14 is an output terminal.

Next, the operation of this embodiment will be explained.

7. The television synchronizing signal added to jj, j, /, 1 is amplified by an amplifier 2 and supplied to one input terminal of a comparator 3 and a rectifier 6. Here, the amplifier 2 may be a simple circuit of an emitter follower whose function is simply to perform impedance conversion to lower the output impedance. The size comparator 3 is a high-speed comparator with high human impedance and is made of a differential amplifier circuit. The television synchronization signal applied to terminal 7 of rectifier circuit 6 is rectified by diodes 9 and 10 via coupling capacitor 8, smoothed by capacitor 11, and converted into a DC voltage. That is, a DC voltage that changes according to the level change of the television synchronization signal can be obtained. Furthermore, this DC voltage is applied to variable resistor 1.
2 and a variable resistor 13 to control the level and potential,'
41 and is supplied to the comparator 3 as a comparison signal via the output terminal 14 of the flow device 6. For example, when the level of the input television synchronizing signal changes from a to a' in FIG. 5, by adjusting the variable resistors 12 and 13, the comparison signal can be set to change as shown by b' in the same figure. Therefore, at the output terminal 5 of the comparator 3, as shown in FIG. 5C, a television synchronization signal whose waveform has been shaped is obtained with very little change in pulse width or phase due to level changes in the input television signal. Furthermore, in conventional circuits, the comparison signal was constant. Therefore, it was not possible to allow the level to decrease below the set position (usually set at 50% of the synchronization signal level), but according to the present invention, the comparison signal changes in proportion to the change in the synchronization signal level. Therefore, the allowable range of level changes increases greatly.

As explained above, according to the present invention, by adding only a small number of circuits, it is possible to perform stable waveform shaping of the synchronization signal without being affected by level changes of the input television synchronization signal, and it has practical effects. is large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional waveform shaping device, FIG. 2 is a signal waveform diagram thereof, FIG. 3 is a block diagram of a waveform shaping device according to an embodiment of the present invention, and FIG. 4 is a wiring diagram of its main parts. , 5th
The figure is a signal waveform diagram. 2. Amplifier, 3.. Comparator, 6.. Rectifier. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 2 @ Figure 5

Claims (1)

[Claims] A waveform shaping device comprising an amplifier that amplifies a television synchronization signal, a rectifier that rectifies the output of the amplifier, and a comparator that compares the output of the amplifier and the output of the rectifier.