JPS5913416A - Waveform shaping circuit - Google Patents

Abstract

PURPOSE:To obtain easily square waves having the frequency corresponding to twice or more the frequency of an input signal source by taking out prescribed- shaped outputs from an output terminal constituted so that the output is taken out by turning on/off a switching transistor (TR) by a rectified and composed output. CONSTITUTION:Diodes D1, D2, D3, D4 rectify outputs generated from both ends of the secondary winding of a transformer T1 and the output terminal of a phase turning circuit and diodes D5, D6 rectify the full wave of the voltage between both ends of the secondary winding of the transformer T1. Respective voltage waveforms V1, V2, V3, V4 are rectified at their half-waves by the diodes D1, D2, D3, D4 and composed with each other at their output terminals. The voltage waveforms V5, V6 are impressed to switching TRs Q1, Q2 respectively. Therefore, the TRs Q1, Q2 are controlled on/off by the composed voltages V1, V6 respectively, and only when both TRs Q1, Q2 are turned on simultaneously, the potential V7 of a connection point between a resistor R5 and a diode D7 is turned to the low level. Consequently, a square wave with the frequency corresponding to twice the frequency of the input signal source E1 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waveform shaping circuit for obtaining a rectangular wave signal whose waveform is twice or several times the frequency of an input signal.

Generally, a display for displaying the current time and a display for displaying the alarm time are provided separately, and these displays are alternately activated at the frequency of the commercial power supply, so that the current time and alarm time are displayed at the same time. Digital display clocks are known that are configured to be displayed separately on a display. By the way, this type of digital display clock requires a constant clock signal to operate each display alternately, but in this case, the commercial power supply is one of them! If the waveform is shaped and used as a clock signal, each display will alternately switch to the operating state at the frequency of the commercial power supply frequency due to the operating function of the clock circuit. Commercial power frequency is 60Hz or 60
Hz, so the switching frequency of the display is 25H2 or 3
There is a problem in that the display becomes 0H2 and a large flicker occurs in the display itself.

In view of the above, the present invention provides an excellent waveform shaping circuit that can easily obtain a shaped rectangular wave having a frequency twice or several times higher with a simple configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A waveform shaping circuit according to the present invention will be described below with reference to drawings of an embodiment. FIG. 1 is an electrical connection diagram of an embodiment of the waveform shaping circuit of the present invention. In the figure, Et is an input signal source such as a commercial power supply, TI is a primary winding connected to an input signal source El, The transformer, R1, CI, and R2, 'C2, whose middle point of the secondary winding is grounded, are connected in series with each other, forming a phase rotation circuit in which both ends are respectively connected to both ends of the secondary winding of the transformer Tl. resistors and capacitors D+, D2, D3, and D4 are diodes and D5 for rectifying the output appearing at both ends of the secondary winding of the transformer T1 and the output end of the phase rotation circuit, respectively. D6 is a diode for rectifying the voltage across the secondary winding of the transformer TI, C3 is a diode Ds, a smoothing capacitor I Ql for smoothing the voltage rectified by D6, and Q2 are connected in series with each other. The bases are connected to the diode D+ through resistors R3 and R4, respectively.
, D2, D3, and D4 are connected to the output ends of switching transistors, R5 acts as a collector load of the transistor Ql, and a load resistor D7 is connected to the transistor Q.
This is the diode connected between the lid and the resistor R5, and the & is the diode at the power supply terminal Woo.

This is a load circuit, such as a clock circuit, which is connected to the output terminal of D6 and whose clock signal input terminal is connected to the connection point between resistor R5 and diode D7.

In the above embodiment, the resistor R constituting the phase rotation circuit is now
Assume that the AC impedances of 1, R2, capacitor CI, and 02 are all the same. And capacitor O1,
(Ignoring the loss of z and drawing an equinodal circuit for this part, the second
The result will be as shown in the figure. In Fig. 2, the current flowing through resistor R2 and capacitor C2 is I+, capacitor Ct,
These currents are: I2 is the current flowing through resistor R1, vR is the voltage across resistor R1, and vc is the voltage across capacitor C1.

The voltage relationship is as shown in the vector diagram shown in FIG. Therefore, the voltage at each connection point of resistor R2 and capacitor C1, resistor R2 and capacitor Cz, resistor R1 and capacitor 01°, resistor R1 and capacitor C2 is -t'Vl
, V2, Va, and V4, and if these are expressed centering on the ground potential, the result will be as shown in the vector diagram shown in FIG. That is, these voltages V+, V2. V3 and v4 have the same magnitude and are shifted in phase by 900 (T).

FIG. 5 shows these voltage waveforms, and each voltage waveform V+, V2, V3, V4 is connected to the diode D1. The signals are half-wave rectified by D3, D2, and D4, and are combined together at their output terminals. Therefore, the combined voltage V
s and V6 are respectively shown in FIG. 6 V5. V6, and these are the switching transistors Q
1, and will be applied to Q2. Therefore, the transistors Ql and Q2 are connected to the above-mentioned combined voltages vs and v6, respectively.
The potential v7 at the connection point between the resistor R5 and the diode D7 becomes low level only when both transistors Q+- and Q2 are turned on. That is, since transistors QI and Q2 are connected in series, they form a so-called AND circuit, and the collector potential of transistor Qt becomes low level only when both transistors Q+ and Q2 are turned on. therefore.

As shown in FIG. 6, the potential v7 at the connection point between the resistor R5 and the diode D7 becomes a rectangular wave with a frequency 2@ of the frequency of the input signal source 1ct.

Note that the diode D7 connected to the collector of the transistor Ql uses the voltage that has been reduced, rectified and smoothed by the transformer T1 as it is as the power supply voltage for the transistors Ql and Q2, so the diode D5. D6 capacitor C3
From the rectified and smoothed voltage, the diodes Dl and D2
, D3, and D4 are higher in voltage, which prevents the current from flowing backward toward the power supply, and is not necessarily necessary when using another power supply as the power supply for transistors Q+Q2. It is something.

Although only two phase rotation circuits are provided in the embodiment, by providing more phase rotation circuits and arbitrarily selecting the phase difference between the respective output terminals, it is possible to obtain a frequency four times or more than the frequency of the input signal source. It is also easy to obtain a square wave.

As is clear from the above embodiments, according to the present invention, it is possible to easily obtain a rectangular wave with a frequency twice or more than the frequency of the input signal source, and it can be used in clock circuits etc. powered by commercial power. This is particularly effective.

[Brief explanation of drawings]

Fig. 1 is an electrical connection diagram of one embodiment of the waveform shaping circuit of the present invention, Fig. 2 is an equivalent circuit diagram of the same main part, Figs.
The figure is a vector diagram showing the current and voltage of the same main parts, and FIG. 5 is a waveform diagram of each part of the same embodiment. E]... Input signal source, TI... Transformer, R1゜R2, Ox, 02... Resistance capacitor that constitutes the phase rotation circuit, Dl-D7...・Diode, R3~R5...Resistance, Ql, Q
2...Switching transistor.

Claims (1)

[Claims] Multiple phase rotation circuits consisting of resistors and capacitors are connected between both ends of the secondary winding of a transformer whose center point is grounded.
The outputs of these phase rotation circuits and the outputs appearing at both ends of the secondary winding of the transformer are rectified and combined, and a separately provided switching transistor is controlled on and off by the rectified and combined output, and the output of the transistor is A waveform shaping circuit configured to output a waveform-shaped output as required.