JP2008292457A - Detector and method for detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve response and detection precision of a detector. <P>SOLUTION: This torque sensor 1 outputs a prescribed number of drive signals to a resonance circuit 2 and performs a free vibration wave counting process for counting the number of free vibration waves attenuatingly output from the resonance circuit 2 after outputting of the drive signals is stopped. By referencing a timing at which the counted number of the free vibration waves reaches the prescribed number in the free vibration wave counting process, the torque sensor 1 repeats the free vibration wave counting process in an endless manner, and outputs a timing signal every time when the number of times of repeating the free vibration wave counting process reaches a prescribed number. As a process performed concurrent with the free vibration wave counting process, the torque sensor 1 measures a time period used for the prescribed number of times of the free vibration wave counting processes, and then outputs the measured time period in a prescribed signal format. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a detection device and a detection method for driving a resonance circuit formed by connecting a detection coil and a capacitor and performing detection based on a phase shift component of a vibration wave output from the resonance circuit, and more particularly, a magnetic method. The present invention relates to a detection apparatus and a detection method for detecting proximity, displacement, material, stress, temperature, fatigue, damage, defect, and the like of a metal based on various characteristic changes.

  A detection device including a detection coil is known. For example, the proximity sensor described in Patent Document 1 is a high-frequency oscillation type proximity switch including a high-frequency oscillation circuit including a detection coil. When a metal approaches the detection coil, the oscillation amplitude and oscillation frequency of the high-frequency oscillation circuit are low. Utilizing the change, the proximity and material of the metal are judged. That is, the oscillation amplitude and oscillation frequency of the high-frequency oscillation circuit not only change according to the proximity distance to the metal, but also change according to the metal material (difference in magnetic permeability, conductivity, etc.), for example, The proximity switch of the amplitude measurement system can detect the proximity of magnetic metal (such as iron) well, and the proximity switch of the frequency measurement system can detect the proximity of non-magnetic metal (such as aluminum). Further, the proximity switch having both types can detect the proximity of the magnetic metal and the nonmagnetic metal well, and can also perform the metal material determination well.

  However, the conventional frequency measurement type detection apparatus measures a slight phase shift while continuing high-frequency oscillation, so that a complicated circuit such as a synchronous detection circuit is required, and the amplitude measurement type detection apparatus There is a problem that it is extremely expensive. Although a slight phase shift can be detected by a digital circuit, in this case, a counter and a CPU that operate at extremely high speed are required, which may increase the cost.

  Therefore, the applicant of the present invention provides a resonance circuit in which a capacitor is connected to the detection coil, a drive signal output means for outputting a drive signal to the resonance circuit, and the resonance circuit after the signal output of the drive signal output means is stopped. In the past, a proximity sensor provided with a phase shift measuring means for measuring a phase shift of a vibration wave accompanying the proximity of a metal based on a free vibration wave output in a damped manner has been proposed (see Patent Document 2). According to such a proximity sensor, it is possible to accurately measure the phase shift of the vibration wave accompanying the proximity of the metal with a simple circuit configuration. That is, in the free vibration wave output in a damped form from the resonance circuit, not only the phase shift of the vibration wave accompanying the proximity of the metal appears clearly, but also the phase shift is accumulated by the number of vibration waves, Even an inexpensive digital circuit that does not have a high-speed counter can measure the phase shift with high accuracy.

  Further, the applicant counts the number of free vibration waves output from the resonance circuit after stopping the signal output of the drive signal output means, and at the timing when the predetermined number of free vibration waves are counted, the drive signal output means Proposed a proximity sensor that amplifies the phase shift of a free vibration wave by repeating a regression operation of outputting a driving signal to a predetermined number of times (Japanese Patent Application No. 2006-232267).

Furthermore, the present applicant detects the stress such as compression, tension, and torsion that occurs in the metal by using the accumulation effect of the phase shift in the free vibration wave and the amplification effect of the phase shift by repeating the free vibration wave counting process. Proposed a stress sensor (Japanese Patent Application No. 2007-19347).
Japanese Patent No. 2550621 JP 2007-68082 A

  However, in the embodiment of the proximity sensor and the stress sensor previously proposed by the applicant, as shown in FIG. 20, after the predetermined number of times of free vibration wave count processing is executed, the free vibration wave count processing is interrupted and detected. Since the signal output processing is performed, there is a possibility that not only a good responsiveness cannot be obtained, but also the phase deviation of the free vibration wave during the detection signal output processing is overlooked, and the detection accuracy may be lowered.

In view of the above circumstances, the detection device of the present invention created for the purpose of solving these problems drives a resonance circuit formed by connecting a detection coil and a capacitor, and is output from the resonance circuit. A detection device that performs detection based on a phase shift component of a vibration wave, and outputs a predetermined number of drive signals to the resonance circuit and freely outputs the attenuation signal from the resonance circuit after the drive signal output is stopped. Free vibration wave count processing means for counting the number of vibration waves, and repeating the free vibration wave counting process endlessly with reference to the timing when the free vibration wave count in the free vibration wave counting process reaches a predetermined number Processing means and timing signal output processing for outputting a timing signal each time the number of repetitions of the free vibration wave count processing reaches a predetermined number And a process performed in parallel with the free vibration wave counting process, the time required for the free vibration wave counting process a predetermined number of times is measured based on the timing signal, and the measured time is determined as a predetermined signal. And a detection signal output processing means for outputting in a format.
According to such a detection apparatus, when the time required for the predetermined number of times of free vibration wave counting processing is output in a predetermined signal format, this detection signal output processing can be performed in parallel with the free vibration wave counting processing. Therefore, after executing the free vibration wave counting process a predetermined number of times, compared to the case where the free vibration wave counting process is interrupted and the detection signal output process is performed, a better responsiveness is obtained and the phase during the detection signal output process is obtained. It is possible to eliminate oversight of deviation and improve detection accuracy.

In addition, the detection apparatus of the present invention includes first and second processing modules that perform processing in parallel, and the first processing module includes the free vibration wave count processing means, repetitive processing means, and timing signal output processing means. And the second processing module includes the detection signal output processing means.
According to such a detection apparatus, the present invention can be implemented even in a processing module that does not have a parallel processing function.

The detection signal output processing means outputs a difference between a plurality of measurement times measured by shifting the period.
According to such a detection device, even if the measurement period is extended to improve detection accuracy (extension of the measurement period due to an increase in the number of free vibration wave counts and the number of repetitions), a part of the measurement period is calculated by the difference calculation. Since it can be cut out, a good resolution can be obtained. Further, the output signal can be encrypted based on the measurement period setting and the difference calculation procedure. For example, when the present invention is applied to a currency identification sensor, it is possible to prevent leakage of the identification algorithm by encrypting the output signal.

The detection method of the present invention is a detection method for driving a resonance circuit formed by connecting a detection coil and a capacitor, and performing detection based on a phase shift component of a vibration wave output from the resonance circuit, A predetermined number of drive signals are output to the resonance circuit, and a free vibration wave count process is performed to count the number of free vibration waves output from the resonance circuit after the drive signal output is stopped. The free vibration wave count process is repeated endlessly with reference to the timing at which the free vibration wave count number reaches a predetermined number in the wave count process, and each time the number of repetitions of the free vibration wave count process reaches a predetermined number, a timing signal As a process performed in parallel with the free vibration wave counting process, the time required for the free vibration wave counting process a predetermined number of times The measured based on the timing signal, and outputs the measured time with a predetermined signal format.
According to such a detection method, when outputting the time required for the predetermined number of times of the free vibration wave counting process in a predetermined signal format, this detection signal output process can be performed in parallel with the free vibration wave counting process. Therefore, after executing the free vibration wave counting process for a predetermined number of times, compared to the case where the free vibration wave counting process is interrupted and the detection signal output process is performed, not only a good responsiveness is obtained but also the detection signal output process is In this case, the detection accuracy can be improved.

Further, the present invention is characterized in that a difference between a plurality of measurement times measured by shifting the period is output.
According to such a detection method, even if the measurement period is extended in order to improve detection accuracy (extension of the measurement period due to an increase in the number of free vibration wave counts and the number of repetitions), a part of the measurement period is reduced by the difference calculation. Since it can be cut out, a good resolution can be obtained. Further, the output signal can be encrypted based on the measurement period setting and the difference calculation procedure. For example, when the present invention is applied to a currency identification sensor, it is possible to prevent leakage of the identification algorithm by encrypting the output signal.

  Next, embodiments of the present invention will be described with reference to the drawings. However, the waveform shown in the drawing includes an actual detection waveform and a simulation waveform obtained by synthesizing a waveform image.

[First embodiment]
FIG. 1 is a block diagram illustrating a configuration of a detection device (torque sensor). The detection device shown in this figure is a torque sensor 1 that detects a torsional stress (torque) generated on a rotating shaft (metal) S, and includes a resonance circuit 2 and a detection circuit 3. The resonance circuit 2 is configured by connecting a capacitor C in series or in parallel to a detection coil L disposed close to the rotation axis S, and is driven by a drive signal output from the detection circuit 3. The detection circuit 3 is configured by using, for example, two processing modules 3a and 3b such as a one-chip microcomputer incorporating a CPU, ROM, RAM, I / O, a comparator (comparator), and the like, and is written in the ROM. A detection process described later is performed according to the program.

  The detection circuit 3 outputs a drive signal to the resonance circuit 2 and is generated on the rotation axis S based on the phase shift component of the free vibration wave output from the resonance circuit 2 in an attenuated manner after the output of the drive signal is stopped. Torsional stress is detected. That is, when torque is applied to the rotating shaft S, the magnetic characteristics (such as magnetic permeability) of the rotating shaft S change, and the inductance of the detection coil L changes according to the change. The change in inductance in the detection coil L clearly appears as a phase shift of the free vibration wave output from the resonance circuit 2 in an damped manner. In addition, since the phase shift in the free vibration wave is accumulated by the number of vibration waves, the phase shift that changes according to the stress can be detected with high accuracy.

  The detection circuit 3 outputs a predetermined number of drive signals to the resonance circuit 2 and counts the number of free vibration waves output from the resonance circuit 2 in an attenuated manner after the drive signal output is stopped. A free vibration wave counting process is performed to determine whether or not a predetermined number N has been reached, and a phase shift component of the free vibration wave is detected based on a time measurement required for the free vibration wave counting process. . In this way, the phase shift component of the free vibration wave can be measured using an inexpensive digital circuit.

  The detection circuit 3 repeats the free vibration wave counting process a predetermined number of times with reference to the timing when the free vibration wave count number in the free vibration wave count process reaches a predetermined number, so that the phase shift component of the free vibration wave Are to be amplified. In this way, the phase shift component of the free vibration wave can be arbitrarily amplified by simply increasing the number of repetitions of the free vibration wave count process without complicating the circuit configuration. Can be dramatically improved.

  Further, the detection coil L has a cylindrical shape with a hollow center portion, and is arranged so that the inner peripheral portion thereof faces the outer peripheral portion of the rotation shaft S. In this way, it is possible to suppress the occurrence of errors due to the relative position change between the detection coil L and the rotation axis S, and to further improve the detection accuracy. That is, when the metal is surrounded by the cylindrical detection coil L, the inductance change of the detection coil L due to the relative displacement between the detection coil L and the metal is reduced, and in particular, a columnar shape or a cylinder In the case where the shape metal is surrounded by the cylindrical detection coil L, an inductance change of the detection coil L due to the relative displacement between the detection coil L and the metal can be minimized.

  Next, a specific configuration of the torque sensor 1 will be described.

  The resonance circuit 2 may be a parallel resonance circuit in which the capacitor C is connected in parallel to the detection coil L, but is preferably a series resonance circuit in which the capacitor C is connected in series to the detection coil L. In this way, a maximum Q-fold voltage (for example, 8 times) of the source voltage (for example, 5 V) can be applied to the detection coil L by the action of the series resonance circuit, so that a free vibration wave having a large amplitude can be generated from the resonance circuit 2. Can be output. As a result, it is possible not only to increase the number of free vibration wave counts and further increase the measurement accuracy, but also to be resistant to noise. Moreover, since a free vibration wave having a large amplitude can be directly input to the detection circuit 3 without going through an amplifier, the circuit configuration becomes simpler and the cost can be further reduced.

Note that the maximum voltage V _LMAX applied to the detection coil L can be obtained by the following equation. However, ω ₀ is the resonance angular frequency, L is the inductance of the detection coil L, R is the resistance of the detection coil L, C is the capacitance of the capacitor C, V _S is the source voltage, and Q is the goodness of the resonance circuit.

When the resonance circuit 2 is forcibly vibrated by the drive pulse signal, the detection circuit 3 can forcibly vibrate the resonance circuit 2 by the plurality of drive pulse signals and then stop the output of the drive signal. In this way, the amplitude of the forced vibration wave can be increased compared with the case where the resonance circuit 2 is forced to vibrate with a single drive pulse signal. In particular, if several (for example, six) drive pulse signals are output at a predetermined resonance frequency so that the amplitude of the forced vibration wave is maximized, the free vibration wave output from the resonance circuit 2 after the drive signal output is stopped. It becomes possible to further increase the measurement accuracy by increasing the amplitude.
Incidentally, the resonance frequency f for forcibly oscillating the resonance circuit 2 can be obtained by the following equation.

  Next, a phase shift accumulation operation (amplification operation) in a free vibration wave will be described with reference to FIGS.

  FIG. 2 is an explanatory diagram showing a drive pulse signal waveform (point a) and a vibration waveform (point b) of the resonance circuit. As shown in this figure, the detection circuit 3 outputs a drive pulse signal having a predetermined voltage (for example, 5 V) to forcibly vibrate the resonance circuit 2. At this time, a maximum voltage (for example, 40 V) can be applied to the detection coil L by outputting several (for example, six) drive pulse signals at a predetermined resonance frequency. Then, after stopping the output of the drive pulse signal, a plurality of free vibration waves are output from the resonance circuit 2 in a damped manner.

  3 is an explanatory diagram showing an enlarged tenth free vibration wave, FIG. 4 is an explanatory diagram showing a phase shift when a large torque is applied to the rotating shaft, and FIG. 5 is a graph showing a small torque applied to the rotating shaft. It is explanatory drawing which shows the phase shift at the time. As shown in these drawings, the free vibration wave output from the resonance circuit 2 maintains a sufficient amplitude for detection even if it is the tenth. Here, when torque is applied to the rotating shaft S, the inductance of the detection coil L changes and the phase of the free vibration wave advances. The phase shift of this free vibration wave not only appears clearly compared with the forced vibration wave, but also the number of free vibration waves is accumulated, so it is possible to measure the phase shift with high accuracy even with a low-speed counter. Become. As shown in FIGS. 4 and 5, the phase deviation of the free vibration wave increases as the torque acting on the rotation axis S increases. Therefore, the phase deviation of the free vibration wave acts on the rotation axis S based on the phase deviation of the free vibration wave. Torque can be measured with high accuracy.

  FIG. 6 is an explanatory view showing the relationship between the free vibration waveform (point b) and the comparator output (point c), and FIG. 7 is an enlarged view showing the comparator output when no torque is applied to the rotating shaft. 8 is an explanatory diagram showing a comparator output when a small torque is applied to the rotating shaft, and FIG. 9 is an explanatory diagram showing a comparator output when a large torque is applied to the rotating shaft. As shown in these figures, the free vibration wave output from the resonance circuit 2 maintains a sufficient amplitude for detection even if it is the tenth or so, so that it is converted into a clear rectangular wave by a comparator. Can do. Here, when torque is applied to the rotating shaft S, the phase of the comparator output waveform advances. As is apparent from FIGS. 8 and 9, this phase shift is accumulated as the number of free vibration waves increases, and measurement becomes easier.

  Next, the phase shift amplifying action (accumulating action) by repeating the free vibration wave counting process will be described with reference to FIG.

  FIG. 10 is an explanatory diagram showing the phase shift amplification effect when the free vibration wave count is 5 and the number of repetitions is 10. FIG. The waveform shown in this figure is an output waveform of the resonance circuit 2 in one detection process, and after two drive pulse signals are output and the resonance circuit 2 is forcibly vibrated, the resonance circuit 2 attenuates the waveform. The free vibration wave count process is performed to count the number of free vibration waves to be output and to determine whether the count number has reached the predetermined number 5, and based on the time measurement required for the free vibration wave count process In detecting the phase shift component of the free vibration wave, a waveform obtained when the free vibration wave count process is repeated 10 times with reference to the timing when the free vibration wave count number in the free vibration wave count process reaches a predetermined number 5 is used. The upper waveform shows a case where a larger torque is applied to the rotating shaft S than the lower waveform. As is clear from this figure, when the free vibration wave count process is repeated a predetermined number of times with reference to the timing at which the free vibration wave count reaches the predetermined number in the free vibration wave count process, the phase deviation of the free vibration wave is amplified. Is done. Thereby, the measurement accuracy of the phase shift can be greatly improved by increasing the number of repetitions of the free vibration wave counting process without complicating the circuit configuration.

  Next, the phase shift amplification function (accumulation function) when the free vibration wave count number and the number of repetitions thereof are changed will be described with reference to FIGS.

  FIG. 11 is an explanatory diagram showing the phase shift amplification effect (enlarged detection waveform start end) when the free vibration wave count is 1 and the number of repetitions is 100, and FIG. FIG. 10 is an explanatory diagram showing the phase shift amplification effect (enlarged detection waveform terminal portion) when the number of repetitions is 100. The waveforms shown in these figures are the output waveforms of the resonance circuit 2 in one detection process. After outputting a single drive pulse signal to forcibly vibrate the resonance circuit 2, the waveform is attenuated from the resonance circuit 2. The number of free vibration waves output in the form of a wave is counted, a free vibration wave count process is performed to determine whether or not the count number has reached the predetermined number 1, and based on the time measurement required for the free vibration wave count process When detecting the phase shift component of the free vibration wave, the waveform when the free vibration wave counting process is repeated 100 times with reference to the timing at which the free vibration wave count reaches the predetermined number 1 in the free vibration wave counting process. The upper waveform shows the case where no torque is applied to the rotating shaft S, and the lower waveform shows the case where torque is applied to the rotating shaft S. As can be seen from these figures, the phase shift is not so amplified at the beginning of the detected waveform, that is, at the stage where the number of repetitions of the free vibration wave count process is small (see FIG. 11), but the free vibration wave count process is not performed. It can be seen that as the number of repetitions increases, the phase shift of the free vibration wave is amplified and the detection becomes easier (see FIG. 12).

  Now, the detection circuit 3 of the torque sensor 1 according to the embodiment of the present invention uses the accumulating action of the phase deviation in the free vibration wave and the amplification action of the phase deviation due to the repetition of the free vibration wave counting process to rotate the rotation axis S. In detecting the torque applied to the output, a predetermined number of drive signals are output to the resonance circuit 2 and the number of free vibration waves output from the resonance circuit 2 in an attenuated manner after the drive signal output is stopped is free. The vibration wave count processing means, the repetition processing means for repeating the free vibration wave count process endlessly with reference to the timing when the free vibration wave count in the free vibration wave count process reaches a predetermined number, and the free vibration wave count process Timing signal output processing means for outputting a timing signal each time the number of repetitions reaches a predetermined number, and free vibration wave count processing. A to processing performed, and a detection signal output processing means for the time required for the free vibration wave counting a predetermined number of times is measured based on the timing signal, and outputs the measured time with a predetermined signal format. In this way, since the detection signal output process can be performed in parallel with the free vibration wave counting process when outputting the time required for the predetermined number of times of the free vibration wave counting process in the predetermined signal format. Compared with the case where the free vibration wave counting process is interrupted and then the free vibration wave counting process is interrupted and the detection signal output process is performed, not only a good response is obtained, but also the phase shift during the detection signal output process Oversight can be eliminated and detection accuracy can be improved.

  The detection circuit 3 of the present embodiment includes first and second processing modules 3a and 3b that perform processing in parallel. The first processing module 3a includes free vibration wave count processing means, repetitive processing means, and Timing signal output processing means is provided, and the second processing module 3b is provided with detection signal output processing means. In this way, the present invention can be implemented even in a processing module that does not have a parallel processing function.

  Next, a specific detection processing procedure and its operation of the detection circuit 3 will be described with reference to FIGS.

  FIG. 13 is a flowchart showing the detection processing procedure of the detection circuit (first processing module). As shown in this figure, the first processing module 3a first sets the REF voltage of the comparator (S11), then the counter clear process (S12) and the free vibration wave count process (S13 to S15: free vibration). Detection processing consisting of wave count processing means), free vibration wave count processing repetition processing (S16, S17: repetition processing means), and timing signal output processing (S18: timing signal output processing means).

  The counter clear process is a process for clearing the repeat count counter (S12). In the free vibration wave counting process, several drive pulse signals are output at a predetermined resonance frequency to the resonance circuit 2 so that the amplitude of the forced vibration wave is maximized (S13), and then the free vibration wave counter is output. Is cleared (S14), the number of free vibration waves output in a damped form from the resonance circuit 2 is counted, and whether or not the count number has reached a predetermined number N is determined (S15). In the iterative process, at the timing when the free vibration wave count reaches the predetermined number N, the repetition number counter is incremented (S16), and it is determined whether or not the repetition number counter has reached the predetermined number M ( S17) is a process of repeating the free vibration wave counting process (S13 to S15) until the determination result is YES. The timing signal output process is a process for outputting a predetermined timing signal (pulse signal, inverted signal, etc.) to the second processing module 3b when the number of repetitions of the free vibration wave counting process reaches a predetermined number M. (S18). Note that the timing signal output process is a process that can be executed in an extremely short time compared to the detection signal output process. The timing signal output process is executed every time the number of repetitions of the free vibration wave count process reaches a predetermined number M. However, the repetition frequency of the free vibration wave counting process is substantially not affected, and the free vibration wave counting process can be repeated endlessly at a substantially constant period.

  FIG. 14 is a flowchart illustrating a detection processing procedure of the detection circuit (second processing module). As shown in this figure, the second processing module 3a first determines the input of a timing signal (S21). If the determination result is YES, a predetermined detection signal output process (S22 to S24: detection signal) Output processing means). In the detection signal output process, the time measurement counter value is acquired in response to the current timing signal input (S22), and the difference from the time measurement counter value acquired at the previous timing signal input (predetermined number of free vibration wave counting processes) Is a process of calculating and outputting the difference value into a predetermined signal format (S24). As shown in FIG. 15, this detection signal output process is performed in parallel with the free vibration wave counting process. Therefore, after the predetermined number of times of free vibration wave counting process is executed, the free vibration wave counting process is interrupted. Compared with the case where detection signal output processing is performed, not only good responsiveness can be obtained, but also an oversight of phase shift during detection signal output processing can be eliminated, and detection accuracy can be improved.

[Other Embodiments]
In the above embodiment, every time the timing signal is output, the time required for the predetermined number of times of free vibration wave counting processing is calculated. However, as in the second embodiment shown in FIG. A timing signal may be output each time the above is repeated, and a time required for a predetermined number of free vibration wave counting processes may be calculated at a timing when the number of output timing signals reaches a predetermined number. In FIGS. 15 and 16, the measurement periods of the time required for the predetermined number of times of free vibration wave counting processing are set so as not to overlap each other, but as in the third embodiment shown in FIG. You may set so that a part may overlap.

  As in the fourth embodiment shown in FIGS. 18 and 19, a difference between a plurality of measurement times measured by shifting the period may be output. For example, in the first to third embodiments, as shown in FIGS. 15 to 17, each time measurement period ends, the measurement time of that period is output. In the fourth embodiment, 19, every time the time measurement period ends, the difference between the measurement time of the previous period and the measurement time of the current period is calculated and output (specific processing is as follows). (See S34 to S36 in FIG. 18). In this way, even if the measurement period is extended in order to improve the detection accuracy (extension of the measurement period accompanying an increase in the number of free vibration wave counts and the number of repetitions), a part of the measurement period can be cut out by the difference calculation. Therefore, good resolution can be obtained. Further, the output signal can be encrypted based on the measurement period setting and the difference calculation procedure. For example, when the present invention is applied to a currency identification sensor, it is possible to prevent leakage of the identification algorithm by encrypting the output signal.

  Note that the present invention is not limited to the above-described embodiment, and of course, as long as the detection is performed based on the phase shift component of the vibration wave output from the resonance circuit, the present invention is not limited to the torque sensor. The present invention can also be applied to a detection apparatus and a detection method for detecting proximity, displacement, material, stress, temperature, fatigue, damage, defect, and the like. In the above embodiment, the resonance circuit is directly driven by the drive signal output from the detection circuit. However, the detection circuit can also be implemented by indirectly driving the resonance circuit by electromagnetic induction or the like. For example, it is also suitable for a metal state detection device that drives an excitation coil provided separately from a detection coil and detects a change in an alternating magnetic field generated from the excitation coil in response to the drive by a detection coil (resonance circuit). Can do.

It is a block diagram which shows the structure of a torque sensor. It is explanatory drawing which shows a drive pulse signal waveform (a point) and the vibration waveform (b point) of a resonance circuit. It is explanatory drawing which expanded the tenth free vibration wave. It is explanatory drawing which shows the phase shift when a big torque is applied to a rotating shaft. It is explanatory drawing which shows the phase shift when a small torque is applied to a rotating shaft. It is explanatory drawing which shows the relationship between a free vibration waveform (b point) and a comparator output (c point). It is an enlarged view which shows the comparator output when the torque is not applied to the rotating shaft. It is explanatory drawing which shows a comparator output when a small torque is applied to the rotating shaft. It is explanatory drawing which shows a comparator output when a big torque is applied to a rotating shaft. It is explanatory drawing which shows the amplification effect | action of a phase shift in case the number of free vibration wave counts is 5 and the repetition frequency is 10. It is explanatory drawing which shows the amplification effect | action of a phase shift (a detection waveform start end part is expanded) when a free vibration wave count number is 1 and the repetition frequency is 100. It is explanatory drawing which shows the amplification effect | action (expansion of a detection waveform termination | terminus part) of a phase shift when the free vibration wave count number is 1 and the repetition frequency is 100. It is a flowchart which shows the detection processing procedure of a detection circuit (1st processing module). It is a flowchart which shows the detection processing procedure of a detection circuit (2nd processing module). It is a timing chart which shows the effect | action which concerns on embodiment of this invention. It is a timing chart which shows the effect | action which concerns on 2nd embodiment of this invention. It is a timing chart which shows the effect | action which concerns on 3rd embodiment of this invention. It is a flowchart which shows the detection processing procedure of the detection circuit (2nd processing module) which concerns on 4th embodiment of this invention. It is a timing chart which shows the effect | action which concerns on 4th embodiment of this invention. It is a timing chart which shows the effect | action which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torque sensor 2 Resonance circuit 3 Detection circuit 3a 1st processing module 3b 2nd processing module C Capacitor L Detection coil S Rotating shaft

Claims (5)

A detection device that drives a resonance circuit formed by connecting a detection coil and a capacitor and performs detection based on a phase shift component of a vibration wave output from the resonance circuit,
A free vibration wave count processing means for outputting a predetermined number of drive signals to the resonance circuit and counting the number of free vibration waves output from the resonance circuit after the drive signal output is stopped;
Repetitive processing means for repeating the free vibration wave counting process endlessly with reference to the timing at which the free vibration wave count number reaches a predetermined number in the free vibration wave counting process,
Timing signal output processing means for outputting a timing signal each time the number of repetitions of the free vibration wave counting process reaches a predetermined number;
A process performed in parallel with the free vibration wave counting process, measuring a predetermined number of times of the free vibration wave counting process based on the timing signal, and outputting the measured time in a predetermined signal format A detection signal output processing means for performing detection. Comprising first and second processing modules for performing processing in parallel;
The first processing module includes the free vibration wave count processing means, a repetition processing means, and a timing signal output processing means,
The detection apparatus according to claim 1, wherein the second processing module includes the detection signal output processing means.   The detection apparatus according to claim 1, wherein the detection signal output processing means outputs a difference between a plurality of measurement times measured by shifting a period. A detection method of driving a resonance circuit formed by connecting a detection coil and a capacitor and performing detection based on a phase shift component of a vibration wave output from the resonance circuit,
A predetermined number of drive signals are output to the resonance circuit, and a free vibration wave count process is performed to count the number of free vibration waves output from the resonance circuit after the drive signal output is stopped,
Based on the timing at which the free vibration wave count in the free vibration wave count process reaches a predetermined number, the free vibration wave count process is repeated endlessly,
A timing signal is output each time the number of repetitions of the free vibration wave count process reaches a predetermined number,
As a process performed in parallel with the free vibration wave counting process, a time required for the free vibration wave counting process a predetermined number of times is measured based on the timing signal, and the measured time is output in a predetermined signal format. A detection method characterized by.   The detection method according to claim 4, wherein a difference between a plurality of measurement times measured at different periods is output.

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