JPH07264002A - Integration circuit - Google Patents

Abstract

PURPOSE:To shorten integration detecting time by including a passage circuit which makes a full-wave rectified AC signal pass for at least a short time of one period and integrating the output of the passage circuit by an integration part. CONSTITUTION:A timing generation circuit 3 which outputs a switch driving pulse P2 in accordance with one period T of an AC signal S also outputs a rectification timing pulse P1 to keep the rectifying operation timing of the AC signal. The rectification timing pulse P1 is supplied to a rectifier circuit 2, and the switch driving pulse P2 is supplied to a switch 4. The switch 4 is turned on only in the period of switch driving pulse P2, and makes a full-wave rectified signal pass for only one period. Only one period of the full-wave rectified AC signal is taken out by the switch 4, and an integrated output voltage can be obtained by two half waves of the AC signal in the integration part 5. Therefore, the integration detecting time can be shortened, and digital processing can be started earlier, which makes signal processing speed up as a whole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrating circuit, and more particularly to an integrating circuit used for detecting an average value from an input signal.

[0002]

2. Description of the Related Art Generally, as an integrating circuit, a low pass filter including a resistor 81 and a capacitor 82 is often used as shown in FIG. When a full-wave rectified sine wave signal as shown in FIG. 9A is applied to the input terminal 80 of this integrator circuit, its output terminal 83 has an output voltage as shown in FIG. 9B. Occurs. This output voltage gradually increases with each half-wave of the input signal, and the detected voltage E
Leading to.

[0003]

In the above-mentioned conventional example, the detection speed is set by the time constant of the resistor 81 and the capacitor 82, and it takes a long time to reach the predetermined voltage E. Therefore, when the detection output of such an integrator circuit is further A / D converted and digitally processed, the processing time becomes longer by at least the time constant of the integrator circuit, and high-speed signal processing cannot be realized. Occurs.

The present invention has been made in view of the above points, and an object thereof is to provide an integrating circuit in which the integral detection time is shortened.

[0005]

An integrating circuit of the present invention which achieves the above object includes a pass circuit for passing a full-wave rectified AC signal for a short time of at least one cycle, and an output of the pass circuit. The integration section is designed to integrate. In this case, the integrating unit includes an operational amplifier having a first input terminal connected to the reference voltage, a resistor connected between the second input terminal of the operational amplifier and the output terminal of the passing circuit, and an output of the operational amplifier. And a capacitor connected between the end and the second input end. Also, the integrating section can be formed of a resistor and a capacitor. The passing circuit includes a switch inserted in the full-wave rectified signal path and a circuit that generates a timing signal for driving the switch based on the full-wave rectified signal.

[0006]

With this structure, the integration time is limited to a predetermined short time. Then, particularly in the case of the structure as claimed in claim 2, the detection voltage obtained for a long time in the above-mentioned conventional example can be obtained only for a period of one cycle of the AC signal.

According to the third aspect of the invention, the voltage E is not obtained in, for example, one cycle time, and only the voltage in the middle is obtained. This is the detection output of two AC signals. It is effective when it is used to compare (detection outputs of two separately provided integration circuits) or when it is compared with a reference voltage.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments shown in the drawings will be described below. In FIG. 1, 1 is an input terminal for the AC signal S,
Reference numeral 2 is a rectifying circuit for full-wave rectifying the input AC signal S, and 3 is a timing generation circuit for receiving the AC signal S and outputting a switch drive pulse P ₂ corresponding to one cycle T of the AC signal S. The timing generation circuit 3 also outputs a rectification timing pulse P _{1 for} timing the rectification operation of the AC signal. The rectification timing pulse P ₁ is given to the rectification circuit 2, and the switch driving pulse P ₂ is given to the switch 4. The switch 4 is O only during the period of the switch drive pulse P _2.
It becomes N, and the full-wave rectified signal from the rectifier circuit 2 is passed for one cycle.

Reference numeral 5 is an integrating unit. Specific examples of the integrating unit 5 are shown in FIGS. 2 and 3, respectively. In FIG. 2, the operational amplifier 7, the resistor R connected to the inverting input terminal of the operational amplifier 7, the inverting input terminal and the output terminal 6 are included.
And a capacitor C connected between and. The non-inverting terminal of the operational amplifier 7 is connected to the ground.

In FIG. 2, full-wave rectified AC signal S
₁ is taken out by the switch 4 for one cycle, and is led to the inverting terminal of the operational amplifier 7 through the resistor R. In this circuit, the capacitor C is charged by the current i for each negative half-wave input. The state of this charging operation is shown in FIG. In FIG. 4, (a) shows an input AC signal for one cycle, and (b) shows the voltage of the output terminal 6. The two half waves of the AC signal cause the integrated output to be the voltage E.

Next, in the embodiment shown in FIG.
1 and a capacitor C1 and is the same as the conventional example of FIG. 8 in this sense, but the main difference is that the full-wave rectified signal switches the switch. Since it is given for one cycle after that, the time constant of the integrating circuit can be significantly smaller than that of the conventional example.

The integration operation of FIG. 3 is shown in FIG. In this case, the integrated output rises only to the voltage E ₁ and does not reach the voltage E with only two half waves shown in FIG.
Therefore, in the case of FIG. 3, it is effective to use it not for outputting the voltage E but for comparing the integrated output E ₁ with a predetermined reference voltage. Further, as shown in FIG. 6, it is effective to prepare two integrating circuits 9a and 9b and use them for comparing the integrated outputs of the two AC signals with the comparator 10 and for taking a difference.

According to the integrating circuit of this embodiment, the integrating unit 5 is constructed as shown in FIG. 2 and FIG.
It has an advantage that the integral detection time becomes short. Therefore,
When the integrated detection output is A / D converted and digitally processed, the digital processing can be started quickly, and the signal processing can be speeded up as a whole.

In the above embodiment, the period for operating the switch 4 is one cycle, but it may be two cycles, for example. However, it is desirable to avoid making it shorter than one cycle. For example, in the case of 1/2 cycle, when the amplitude of the first half wave of the AC signal is originally large and the amplitude of the next half wave (shown by the dotted line) is small as shown in FIG. 7, when full-wave rectification is performed, As a matter of course, since the magnitudes of the first half wave and the second half wave are different, if the half wave is integrated, correct integral detection cannot be performed.

In the above embodiment, a sine wave signal is shown as the input AC signal, but it is not limited to such a sine wave signal and other kinds of AC signals may be used.

[0016]

As described above, according to the present invention, there is an effect that the integral detection time is shortened. Therefore, when the signal processing is performed using the integrated detection output, the signal processing can be started earlier, and the signal processing can be speeded up.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an integrating circuit embodying the present invention.

FIG. 2 is a circuit diagram showing a first specific example of the integrating unit.

FIG. 3 is a circuit diagram showing a second specific example of the integrating unit.

FIG. 4 is a signal waveform diagram for explaining the operation of FIG.

5 is a signal waveform diagram for explaining the operation of FIG.

6 is a diagram showing an application example using the circuit of FIG.

FIG. 7 is a diagram illustrating a switch operation timing time.

FIG. 8 is a circuit diagram showing a conventional integrating circuit.

FIG. 9 is an operation explanatory diagram thereof.

[Explanation of symbols]

2 Rectifier circuit 3 Timing generator circuit 4 Switch 5 Integrator 7 Operation amplifier R Resistor C Capacitor S AC signal S ₁ Full-wave rectified AC signal

Claims (4)

[Claims] 1. An integrating circuit including a pass circuit for passing a full-wave rectified AC signal for a short time of at least one cycle, and an output of the pass circuit is integrated by an integrating section. 2. The integrating unit includes an operation amplifier having a first input terminal connected to a reference voltage, a resistor connected between a second input terminal of the operation amplifier and an output terminal of the passing circuit, and the operation unit. The integrating circuit according to claim 1, comprising an output terminal of an amplifier and a capacitor connected between the second input terminal. 3. The integrating circuit according to claim 1, wherein the integrator comprises a resistor and a capacitor. 4. The pass circuit comprises a switch inserted in the full-wave rectified signal path, and a circuit for generating a timing signal for driving the switch based on the full-wave rectified signal. 3. The integrating circuit according to any one of 3 above.