JPS62162970A - Output device for alternating current signal varying in amplitude - Google Patents

Abstract

PURPOSE:To output an AC input signal which varies in amplitude with good response by detecting and outputting sampling data which is sampled by a sample holding circuit at timing succeeding a sampling command. CONSTITUTION:The sample holding circuit 14 samples and holds the peak level of each waveform of an input AC signal. This sampling data is supplied to an A/D converting circuit 18 and converted into digital data, which is supplied as an A/D conversion command from the circuit 18. Sampling data corresponding to the peak level of the input AC signal is therefore converted into digital data by the circuit 18 right after the sampling. The output digital data of this circuit 18 is outputted from an output terminal 21 through a buffer circuit 20. Data latched by a latch circuit 19, on the other hand, is converted by a D/A converting circuit 22 into analog data to output an analog DC voltage signal from an output terminal 23. Consequently, the signal is outputted with good response to the input signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention expresses the measurement result by the amplitude of an alternating current signal, for example, by converting the above-mentioned measurement signal from a rotational torque detection device into digital data or analog data. The present invention relates to an output device for outputting an AC signal whose amplitude changes.

[Background Art] In order to convert an amplitude-modulated high-frequency voltage signal into digital data, the high-frequency human input signal is supplied to an integrating circuit composed of a resistor and a capacitor, for example, and converted into a DC voltage signal. Generally, a DC voltage signal is converted into digital data using an A/D converter.

In this case, in order to accurately reproduce the amplitude of the high-frequency input signal, the time constant of the time constant circuit made up of the resistor and capacitor that constitutes the integration circuit is set to a large value, so the response to changes in the input signal is is very bad. Therefore, for example, in a measuring device that extracts an amplitude-modulated high-frequency alternating current signal as a measurement signal, it is difficult to output the measurement results in a timely manner, and it is difficult to perform highly accurate measurement operations. It also becomes difficult.

In addition, if the integration time constant of the integration circuit is set to a small value in consideration of these points, the response will be improved, but the ripple corresponding to the AC component of the input signal will be large. As a result, accurate digital conversion data cannot be obtained.

[Problems to be Solved by the Invention] This invention has been made in view of the above points, and is a method for converting, for example, amplitude-modulated high-frequency AC signals into digital data or analog data with sufficient responsiveness. It is an object of the present invention to provide an output device for alternating current signals whose amplitude changes, which can be effectively used as an output device for various measuring devices and the like.

[Means for Solving the Problems] That is, the output device for an alternating current signal whose amplitude changes according to the present invention is configured to half-wave rectify an input alternating current signal and supply it to a sample hold circuit, A sampling command is given to the sample and hold circuit in accordance with the timing of the peak of
This sampled data is appropriately A/D converted or latched and stored as it is to be output.

[Function] In the output device configured as described above, the state of waveform change of the input AC signal is first detected by the half-wave rectifier circuit, and the half-wave rectified waveform is detected by the half-wave rectifier circuit. The peak state will be sampled and stored. Immediately after being sampled, this sampling data is appropriately converted into analog data or A/D and output as digital data. Amplitude data of the signal is output, and a highly accurate output signal with sufficient responsiveness can be obtained.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows its configuration, and an input terminal 11 receives, for example, an amplitude-modulated alternating current signal from a rotational torque detection device (described later), in which the measured value is expressed as a voltage value. .

This input AC signal is amplified by an amplifier circuit 12 and then sent to a half-wave rectifier circuit 1 including diodes 13a, 13b, etc.
The input AC signal is supplied to sample hold circuit 14 and is half-wave rectified by this circuit 13.

Further, the AC signal amplified by the amplifier circuit 12 is supplied to a phase shift circuit 15. This phase shift circuit 15 includes a resistor 151
．． 152 Furthermore, the amount of phase shift is set by a capacitor 153, and the amount of phase shift is finely adjusted by a variable resistor 152. Specifically, the amplifier circuit 1
The output signal from this phase shift circuit 15 is supplied to the comparator IB. The comparator 16 compares the human input signal with a ground potential, and is set to supply a trigger signal to the one-shot generator 17 when the input signal level changes beyond the ground level.

Therefore, the comparator 16 gives a trigger command to the one-shot circuit 17 at the timing when the signal obtained by shifting the input AC signal by 90 degrees rises above the ground level. A one-shot pulse signal that rises at the peak level of the signal, particularly the half-wave rectified signal, is generated. The output pulse signal a from this one shot circuit 17 is supplied to the sample hold circuit 14 as a sampling command.

That is, in this sample hold circuit 14,
The peak level of each waveform of the input AC signal is sampled and stored, and the sampled data is supplied to the A/D conversion circuit 18 to be converted into digital data. Conversion circuit 1
Digital data from 8 is supplied to latch circuit 19.

Here, the one-shot circuit 17 further generates a pulse signal S for a conversion command in response to the fall of the sampling command a, and this pulse signal S is sent to the A/D conversion circuit 18 to convert the A/D Supplied as a conversion command. That is, the sampling data corresponding to the peak level of the input AC signal is converted into digital data by the A/D conversion circuit 18 immediately after being sampled.

In addition, a pulse signal C is generated from this A/D conversion circuit I8 corresponding to the timing when A/D conversion is executed in this A/D conversion circuit 18, and this pulse signal C gives a latch command to the latch circuit 19. The digital data is latched and stored in response to this command.

The output digital data from the A/D conversion circuit 18 is further outputted as, for example, 8-bit digital data from the output terminal 21 via the buffer circuit 20, and the data latched by the latch circuit 19 is , is converted into analog data by a D/A conversion circuit 22, and outputted from an output terminal 23 as an analog DC voltage signal.

The output device configured in this manner can be effectively used, for example, as an output device of a torque detection device for a screwdriver 30 for tightening screws as described in FIG. 2.

This driver 30 includes a DC motor 31 as a drive source, and the rotation of this motor 31 is transmitted via a gear mechanism 32 and further a torque conversion mechanism 33 to a bit 34 that applies rotational force to a tightening screw. There is.

FIG. 3 shows the torque conversion mechanism 33 taken out, and includes a torsion bar 35 that transmits rotational force from the gear mechanism 32 to the bit 34 section. This torsion bar 3
At both ends of 5, there are first iron cores 36 for excitation, respectively.
A second iron core 37 for detection is installed, and the first and second iron cores 36 and 3
7 respectively extend parallel to the torsion bar 35.
Book magnetic poles 381-384 and 391-394 are provided.

Here, the above magnetic poles 381 to 384 and 391 to 39
The four parts are set to face each other with a small interval between them, and the magnetic pole faces of the magnetic poles 391 to 394 are located at the center position between the magnetic pole faces of the magnetic poles 381 to 384, respectively. It is set as follows. The magnetic poles 381 to 384 have windings 401 to 404 each having an equal number of turns and alternately winding directions opposite to each other.
These windings 401 to 404 are connected in series, and a high frequency alternating current is supplied to these windings from the oscillating section 41 via the rotary transformer 42 as appropriate.

Further, the magnetic poles 391 to 394 of the second iron core 37 are also wound with windings 431 to 434 similar to the magnetic poles 381 to 384, and the windings 401 to 404 are connected to the oscillating section 41. When alternating current is supplied, the windings 431~
An induced voltage is generated at 434, and an output AC voltage signal Eo is taken out. This output AC voltage signal Eo is supplied to the measuring section 45 via the rotary transformer 44.
An output device as shown in the figure is set up, and the output AC voltage Eo is supplied as an input signal to an input terminal 11 of this output device.

In the driver 30 as described above, when no load is applied to the pit 34 and rotational torque is not applied, the torsion bar 35 does not twist, and the magnetic pole of the first iron core 3B The magnetic poles 391 to 394 of the second iron core 37 are present at intermediate positions between the magnetic poles 381 to 384, so that magnetic fields of opposite polarity act on each of the magnetic poles 391 to 394 at equal levels. Become. Therefore, in this state, no voltage is induced in the windings 431-434 wound around the magnetic poles 391-394.
Output voltage EO is zero.

When a load torque is present on the bit 34, the torsion bar 35 is moved in response to the magnitude of the torque.
A twist occurs in the magnetic pole 381 corresponding to the amount of twist.
The relative positional relationship between the magnetic poles 391 to 394 and the magnetic poles 391 to 394 changes, and an AC voltage of a level corresponding to the amount of change is induced in the windings 431 to 434. That is, an AC voltage signal having an amplitude corresponding to the torsion of the torsion bar 35 is output as a torque detection measurement signal, and the first
It is now supplied to the output circuit shown in the figure. and,
This output circuit outputs digital data corresponding to the detected torque as described above, or outputs it as an analog DC voltage signal.

That is, in this driver 30, the torque is measured by the amount of change in amplitude of the output AC voltage signal that changes in accordance with the amount of twist of the torsion bar 35, and as the screw tightening operation of this driver 30 is performed, the torque is measured. In order to measure and monitor the torque acting on the screw, it is necessary to perform a fast torque measurement operation. That is, the windings 431 to 43
It is necessary to instantaneously measure the amplitude change of the AC signal induced in 4.

The above output device samples the AC voltage waveform at each peak level and outputs the sampled data as a digital or analog output signal. Detection of rotational torque can also be performed very quickly and with high precision.

In the above embodiment, a half-wave rectified signal is supplied to the sample-and-hold circuit 14, but a full-wave rectified signal may of course be supplied to the A/D conversion circuit 18. . However, in this case, the 1-shot pulse signal is generated from the 1-shot circuit 17 not only when the 90 degree shifted AC signal rises above the ground level, but also at the timing when it falls above the ground level. It needs to be configured like this.

[Effects of the Invention] As described above, in the output device for an AC signal whose amplitude changes according to the present invention, the amplitude is monitored in a state corresponding to each of the waveforms of the AC signal, and is taken out as output data. Therefore, elements such as an integrating circuit having a time constant are not excluded in this signal conversion process.

Therefore, the output can be controlled with very good responsiveness. In addition, since the amplitude of the input AC signal is directly detected and converted into an output signal, the output signal accuracy is set to be sufficiently high and it can be effectively applied as an output device for various measurement devices. It is.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating an output device for an alternating current signal whose amplitude changes according to an embodiment of the present invention, FIG. FIG. 3 is a configuration diagram showing the torque conversion section of the driver. 11...Input terminal, 12...Amplification circuit, 13...
Half-wave rectifier circuit, 14... Sample hold circuit, 15
... Phase shift circuit (9o degree phase shift), 1B... Comparator, 17... 1 shot circuit, 18... A/D conversion circuit, 19... Latch circuit, 22... D/ A conversion circuit.

Claims (1)

[Claims] A half-wave rectifier for half-wave rectifying an AC input signal whose amplitude changes; a sample-and-hold circuit to which the half-wave rectified signal is supplied; and a timing corresponding to the peak of the AC input signal. and means for generating a sampling command to the sample and hold circuit at the timing detected by the means, the sampling data of the sampling circuit sampled by the means is generated at a timing subsequent to the sampling command. An output device for an alternating current signal whose amplitude changes, characterized by detecting and outputting the signal.