JP3094766B2 - Signal processing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor signal processing circuit in various sensors.

[0002]

2. Description of the Related Art A case where a torque sensor is used as a representative example of various sensors will be described below.

FIG. 7 is a sectional view of a torque sensor, and FIG.
It is a circuit diagram of a sensor sensing means by a torque sensor. 7, reference numeral 1 denotes a rotatably supported shaft, 2a, 2b
Is at 45 ° to the longitudinal direction of the shaft 1 and −45
A plurality of slits are formed in the direction of .degree., And amorphous metal ribbons 3a and 3b made of amorphous or the like having magnetostriction are wound outside the amorphous metal ribbons 2a and 2b via bobbins (not shown). An excitation / detection coil that is turned and excited to detect.

In FIG. 8, reference numerals 4a and 4b denote resistors, and reference numeral 5 denotes an AC power supply. Each element of 3a, 3b, 4a and 4b constitutes an AC bridge.

The operation of the torque sensor configured as described above will be described below. Amorphous metal strip 2a the shaft 1 is bonded on the shaft 1 rotates, distortion occurs in 2b, excitation and detection coil 3a for detecting by exciting the permeability change of the distortion, 3b inductance change in And two types of sensing signals are output from the sensor sensing means.

Hereinafter, a signal processing circuit of the torque sensor will be described.

FIG. 9 is a block diagram of a conventional signal processing circuit, and FIG. 10 is this circuit diagram. In FIG. 9, 1
Reference numerals 1 and 12 denote first and second rectification means, 13 denotes subtraction means,
14 is a smoothing means. In FIG. 10, reference numeral 11 denotes first rectifying means, two operational amplifiers 11a and 11b, two diodes 11c and 11d, and three resistive elements 11e and 11e.
f, 11g and a capacitor 11h, and the second rectifier 12 is similarly configured. 13 is a subtraction means, which comprises an operational amplifier 13a and four resistance elements 13b, 13b.
c, 13d and 13e. Reference numeral 14 denotes a smoothing means, which comprises an operational amplifier 14a, a capacitor 14b, and three resistance elements 14c, 14d, and 14e.

The operation of the conventional signal processing circuit configured as described above will be described below. FIG. 11 is a signal waveform diagram at each point.

First, FIG.
As shown in FIG. 1B, sensing signals A and B are input to first and second rectifiers 11 and 12, respectively, to perform full-wave rectification.
The rectification signals A and B shown in FIGS.
Output to

Next, the subtracting means 13 receives the rectified signals A and B shown in FIGS. 11C and 11D outputted from the first and second rectifying means 11 and 12, and A subtraction signal shown in FIG. 11E obtained by subtracting the rectified signal A is output to the smoothing means 14.

Next, the smoothing means 14 receives and subtracts the subtraction signal shown in FIG. 11 (e) output from the subtraction means 13 to obtain a sensor signal shown in FIG. 11 (f).

[0012]

However, in the above-mentioned conventional configuration, the two kinds of sensing signals A and B output from the sensor output sensing means are used for the first and second rectifying means 11 and 12 respectively.
After the full-wave rectification, the subtraction means 13 performs a subtraction process.
If there is a variation in each element because the rectifiers 11 and 12 enter, the peak values of the outputs of the first and second rectifiers 11 and 12 may be different, or the operational amplifier 11
The offset voltages of a, 11b, 12a, 12b, 13a, and 14a were added to the respective signals, and the sensor signals as the output values of the signal processing circuit were significantly different.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a signal processing circuit which is less affected by component variations and an offset voltage of an operational amplifier and has excellent temperature characteristics.

[0014]

In order to achieve this object, a signal processing circuit according to the present invention comprises two types of signal processing circuits according to the output of a sensor.
A sensor output sensing means for outputting a kind of sensing signal;
Control of the switch control means based on the sensing signal of the sensor output sensing means
First switch means and second switch means in response to a signal
Are input alternately and output from the first and second switch means.
And a subtraction means for inputting and subtracting the switched signal.
Has been established.

[0015]

With this configuration, two sensing signals are switched
Switching and subtraction by
Minimal influence of amplifier offset voltage and excellent temperature characteristics
In addition to the high accuracy
Signal processing becomes possible.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. Here, the same components as those in the conventional example are denoted by the same reference numerals, and detailed description is omitted. FIG. 1 is a block diagram of a signal processing circuit of the present invention, and FIG. 2 is a circuit diagram thereof.

In FIG. 1, reference numeral 21 denotes subtraction means, 22 denotes inversion means, 23 denotes first switch means, 24 denotes second switch means, 25 denotes switch control means for controlling the first and second switch means, 26 is a smoothing means.

In FIG. 2, reference numeral 21 denotes a subtraction means, which includes an operational amplifier 21a and four resistance elements 21b, 21c, 21d,
21e. Reference numeral 22 denotes an inverting means, which comprises an operational amplifier 22a and three resistance elements 22b, 22c, and 22d. Reference numeral 23 denotes a first switch, which is constituted by an analog switch.
4 is also configured. Reference numeral 25 denotes switch control means, two operational amplifiers 25a and 25b and six resistance elements 25c,
25d, 25e, 25f, 25g, and 25h, an operational amplifier 25i, a capacitor 25j, and three resistance elements 25.
k, 25l, 25m.
26 is a smoothing means, which includes an operational amplifier 26a and a capacitor 26.
b and three resistance elements 26c, 26d, 26e. 27 and 28 are DC cut capacitors.

The operation of the signal processing circuit configured as described above will be described. FIG. 3 is a signal waveform diagram at each point.

First, from the sensor sensing means, FIG.
The sensing signals A and B having the signal waveforms shown in (b) are input to the subtraction means 21, and the subtraction signal of the signal waveform of FIG. Output to the first switch means 23.

Next, the inverting means 22 inputs the subtraction signal output from the subtracting means 21 and inverts the inverted signal having the signal waveform shown in FIG.

Next, the first switch means 23 controls the subtraction signal output from the subtraction means 21 and the switch control means 25.
And outputs the switch signal A having the signal waveform shown in FIG. 3E to the smoothing means 26 by the switch operation.

Next, the second switch means is the inverting means 22.
3 and the control signal B output from the switch control means 25 are inputted and the switch operation is performed.
The switch signal B having the signal waveform of FIG.
Output to

Next, the smoothing means 26 switches the switch signals A and B output from the first and second switch means 23 and 24.
Is input and smoothed to obtain a sensor signal.

Hereinafter, another embodiment of the present invention will be described with reference to the drawings.

Here, the same components as those in the conventional example are denoted by the same reference numerals, and detailed description is omitted. FIG. 4 is a block diagram of a signal processing circuit of the present invention, and FIG. 5 is a circuit diagram of the signal processing circuit.

In FIG. 4, 31 is first switch means, 32 is second switch means, 33 is switch control means, 34 is subtraction means, and 35 is smoothing means.

In FIG. 5, reference numeral 31 denotes first switch means, which is constituted by a multiplexer, and similarly, second switch means 32 is also constituted. 33 is a switch control means, which comprises an operational amplifier 33a and two resistors 33b, 33b.
c. Numeral 34 denotes subtraction means, which comprises an operational amplifier 34a and four resistance elements 34b, 34c, 34d, 34
e. Reference numeral 35 denotes a smoothing means, which is composed of an operational amplifier 35a, three resistance elements 35b, 35c, 35d, and a capacitor 35e.

The operation of the signal processing circuit of the present invention configured as described above will be described. FIG. 6 is a signal waveform diagram at each operation.

First, the first and second switch means 31, 3
2 receives the sensing signals A and B from the sensor sensing means shown in FIGS. 6A and 6B and the control signal from the switch control means 33 and exchanges the sensing signals A and B according to the control signal;
The switch signals A and B shown in FIGS.

Next, the subtraction means 34 receives the switch signals A and B shown in FIGS. 6C and 6D from the first and second switch means 31 and 32, and switches the switch signal A from the switch signal B. And outputs a subtraction signal shown in FIG.

Next, the smoothing means 35 inputs and smoothes the subtraction signal output from the subtraction means 34, and outputs a sensor signal shown in FIG.

In this embodiment, the sensor output sensing means has been described as a torque sensor that changes in accordance with a change in torque. However, the present invention is not limited to the torque sensor, and outputs two types of sensor signals such as an acceleration sensor and a yaw rate sensor. Anything is applicable.

[0034]

As described above, the signal processing circuit of the present invention has
A sensor that outputs two types of sensing signals according to the output of the sensor
Output sensing means, and a sensing signal of the sensor output sensing means
The first switch according to the control signal of the switch control means.
Means and alternately input to the second switch means,
Inputting the switch signal output from the second switch means
And subtraction means for subtracting
The influence of the offset voltage of the
It has excellent characteristics and small error without inverting amplifier.
High-precision signal processing becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram of a signal processing circuit according to an embodiment of the present invention.

FIG. 2 is the same circuit diagram

FIG. 3 is a signal waveform diagram of the same.

FIG. 4 is a block diagram of a signal processing circuit according to another embodiment of the present invention.

FIG. 5 is the same circuit diagram.

FIG. 6 is a signal waveform diagram of the same.

FIG. 7 is a sectional view of a torque sensor used in a conventional signal processing circuit.

FIG. 8 is a circuit diagram of a torque sensor illustrating an input part of the conventional art.

FIG. 9 is a block diagram of a conventional signal processing circuit.

FIG. 10 is the same circuit diagram.

FIG. 11 is a signal waveform diagram of the same.

[Explanation of symbols]

 Reference Signs List 21 subtraction means 22 inversion means 23 first switching means 24 second switching means 25 switch control means 26 smoothing means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-105209 (JP, A) JP-A-4-184118 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01D 5/00-5/62

Claims (1)

(57) [Claims] 1. Two kinds of sensing signals according to the output of a sensor
Sensor output means for outputting a signal, and the sensor output sensing means
Means according to the control signal of the switch control means
Alternately input to the first switch means and the second switch means
And the switch output from the first and second switch means.
And a subtraction means for inputting and subtracting a switch signal.
Signal processing circuit.