JP2004317262A - Measuring device - Google Patents

Abstract

An object of the present invention is to provide a peak value detection method for obtaining a high-accuracy peak value, and a measuring device for obtaining a high-accuracy peak value, a barrier value, and a high-accuracy correction value.
An A-phase pseudo sine wave and a B-phase pseudo sine wave detected along with the rotational movement of a rotary disk are acquired, and when one of the pseudo sine waves monotonically increases or monotonously decreases the middle range. The other detected peak value or barrier value is latched. This is performed for four cycles while the rotating disk 3 rotates in a single direction. A DC offset value of the A-phase pseudo sine wave and the B-phase pseudo sine wave is obtained based on each of the four peak values and the barrier values latched in four cycles, and the obtained values are used as the A-phase pseudo-sine wave and the B-phase pseudo-sine wave. , The A-phase pseudo sine wave and the B-phase pseudo sine wave are corrected.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a measuring device such as an encoder device.
[0002]
[Prior art]
2. Description of the Related Art As a measuring device for detecting a displacement of a motor, an optical encoder device using a light emitting element, a light receiving element, and a rotating disk provided therebetween is known. A minute slit is formed in the rotating disk to transmit or block light when a positional displacement occurs. This change in light is detected by the light receiving element, and the positional displacement is detected. The output of the light receiving element is amplified by an amplifier circuit to obtain a well-known pseudo sine wave having a phase difference of 90 degrees.
[0003]
The amplified two-phase pseudo sine wave signal is further divided into one wavelength of the sine wave by a subdivision circuit (interpolation circuit) to obtain finer position information. Several methods are known for the subdivision method. A subdivision method is performed by providing a phase difference using a resistance array (resistance division method), or an arctangent function is used using an A / D converter. How to do (tan ^-1 θ method) is widely known. According to these methods, higher-resolution position information segmented than one wavelength of the pseudo sine wave is obtained.
[0004]
At this time, the two-phase pseudo sine wave (A-phase signal, B-phase signal) may have a DC offset due to a mechanical error of the detection system, an electrical offset of the electrical amplification circuit itself, and the like. is there. On the other hand, the method of achieving high resolution by subdividing one wavelength is based on the premise that a pseudo sine wave (A-phase signal, B-phase signal) is theoretically an ideal sine wave and cosine wave. Perform processing. For example, the signals of the A phase and the B phase can be regarded as sin θ and cos θ, and tan θ can be obtained by performing the division of (sin θ) θ (cos θ). Based on the division result (quotient), θ = tan ^-1 (Quotient) is converted to obtain θ corresponding to the position information.
[0005]
Here, when an offset occurs in sin θ and cos θ as the basis of the division, the result of obtaining the inverse trigonometric function is a result having an error from the accurate θ. That is, a position error of the subdivided position information is caused, and the accuracy of the position information is reduced. This decrease in precision results in a significant decrease in performance as a position sensor or measuring instrument. In order to compensate for such a drawback, an adjustment means such as a variable resistor is provided in the circuit while monitoring the voltage waveform of the pseudo sine wave with an oscilloscope or the like, so that a human can manually adjust the offset with a gap between the hands to prevent a decrease in accuracy. That was being done. However, these methods have a problem that a special circuit has to be provided and a human has to perform a fine adjustment with a gap between hands.
[0006]
Therefore, the inventor of the present application has devised a method of detecting a peak value and a barrier value of a pseudo sine wave, calculating an average value for each period, and correcting the pseudo sine wave (for example, see Patent Document 1). In addition, every time the phase A of the pseudo sine wave crosses a certain level, the value of the phase B is sampled, and the phase B is corrected based on the value. Similarly, a method has been devised in which the value of the A phase is sampled each time the B phase crosses a certain level, and the A phase is corrected based on the value (for example, see Patent Document 2).
[0007]
[Patent Document 1]
JP-A-6-26882
[Patent Document 2]
JP-A-6-34392
[Problems to be solved by the invention]
However, the above-described method has a problem in that it is not always possible to obtain a highly accurate peak value or a barrier value, or a highly accurate correction value.
[0008]
The present invention provides a measuring device for obtaining a highly accurate peak value, a barrier value, and a highly accurate correction value.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 uses a first periodic signal and a second periodic signal having substantially the same phase and having a phase difference of substantially 90 degrees detected with the movement of an object to be measured. Signal acquisition means for acquiring a first periodic signal and a second periodic signal, the signal acquisition means being adapted to detect a peak value of the first periodic signal, and obtaining the second periodic signal. When the first periodic signal monotonically increases or monotonically decreases from the first predetermined value to the second predetermined value across the predetermined reference level of the second periodic signal, the peak value of the first periodic signal acquired during that time is calculated as Peak value detection means for detecting as a peak value when the device under test is moving in a single direction.
The invention according to claim 2 uses a first periodic signal and a second periodic signal which have a phase difference of substantially 90 degrees and have the same period, which are detected as the object to be measured is moved. A first correction value detecting means for obtaining a first correction value of the first periodic signal, and a first correction value detecting means for obtaining a first correction value of the first periodic signal. First correction means for correcting the second periodic signal, second correction value detecting means for obtaining a second correction value of the second periodic signal, and a second period based on the second correction value obtained. Correction means for correcting the static signal, and position information of the device under test subdivided by performing subdivision processing based on the corrected first periodic signal and the corrected second periodic signal. And a first correction value detecting means, wherein the second correction signal is a predetermined value of the second correction signal. When monotonically increasing between a first predetermined value and a second predetermined value across a quasi-level, one of a peak value and a bary value of the first periodic signal during the increase is obtained, and the first predetermined value is obtained. And when the value decreases monotonically between the second predetermined value and the other, the other of the peak value or the bary value of the first periodic signal is obtained, and based on the obtained peak value and the bary value of the first periodic signal, The first correction value is obtained, and the second correction value detecting means determines whether the first periodic signal has a third predetermined value and a fourth predetermined value that cross a predetermined reference level of the first periodic signal. When the value increases monotonically between the first and second predetermined values, one of the peak value and the bary value of the second periodic signal is acquired, and when the value monotonically decreases between the third predetermined value and the fourth predetermined value, the second value during the second period increases. The other of the peak value and the bary value of the periodic signal is acquired, and the acquired second It is characterized in that for obtaining a second correction value based on the peak value and Barii value signal.
The invention according to claim 3 uses a first periodic signal and a second periodic signal having a phase difference of substantially 90 degrees and having the same period detected with the movement of the object to be measured. A first correction value detecting means for obtaining a first correction value of the first periodic signal, and a first correction value detecting means for obtaining a first correction value of the first periodic signal. First correction means for correcting the second periodic signal, second correction value detecting means for obtaining a second correction value of the second periodic signal, and a second period based on the second correction value obtained. Correction means for correcting the static signal, and position information of the device under test subdivided by performing subdivision processing based on the corrected first periodic signal and the corrected second periodic signal. And a first correction value detecting means for detecting at least two rounds during the movement of the device under test in a single direction. A first correction value based on the obtained peak value and the validity value of the first periodic signal, and outputs the calculated first correction value to the first correction means. The second correction value detection means acquires the peak value and the bary value for at least two cycles in synchronization with the first periodic signal while the device under test is moving in the single direction, and A second correction value is obtained based on a peak value and a bary value of the second periodic signal, and the obtained second correction value is output to a second correction unit.
According to a fourth aspect of the present invention, in the measuring device according to the third aspect, the first correction value detecting means does not output the first correction value until the peak value and the bary value for at least two cycles are obtained. Outputting a value of zero, and wherein the second correction value detecting means does not output the second correction value or outputs the zero correction value until the peak value and the barrier value for at least two cycles are obtained. Things.
According to a fifth aspect of the present invention, in the measuring device according to any one of the third to fourth aspects, at least two cycles are the number of cycles of a power of two. According to a sixth aspect of the present invention, in the measuring device according to any one of the third to fifth aspects, at least two cycles are counted by turning on the power to the measuring device.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram of an encoder device showing an embodiment of the measuring device of the present invention. The encoder device is attached to a motor or the like and detects a rotational position displacement of the motor. The motor to which the encoder device is attached is used, for example, in a robot. A rotating disk 3 is provided between the light emitting element 1 and the light receiving element 2, and the rotating disk 3 rotates with the rotation of the rotating shaft of the motor. A minute slit is formed in the rotating disk 3 to transmit or block light when a positional displacement occurs. This change in light is detected by the light receiving element 2 to detect the position displacement. The output of the light receiving element 2 is amplified by the amplifier circuit 4 and outputs a known two-phase pseudo sine wave (A phase / B phase). The phases of the A-phase pseudo sine wave and the B-phase pseudo sine wave are shifted by 90 degrees.
[0011]
In the present embodiment, the amplified two-phase pseudo sine wave signal is finely divided by the subdivision circuit (interpolation circuit) 5 into one wavelength of the sine wave to obtain more precise position information. Several methods are known as a subdivision method. A subdivision method is performed by providing a phase difference using a resistance array (resistance division method), or a method using an arctangent function using an A / D converter. (Tan ^-1 θ method) is widely known. According to these methods, higher-resolution position information segmented than one wavelength of the pseudo sine wave is obtained. In the present embodiment, a method using an arctangent function (tan ^-1 θ method).
[0012]
The A-phase pseudo sine wave has a DC offset due to various factors as described in the related art section. The A-phase pseudo sine wave is input to the A / D converter 6 while having a DC offset. One of the outputs (n bits, n: natural number) of the A / D converter 6 is input to the subtracter 7 and the other is input to the DC offset detection circuit 8. Similarly, the B-phase pseudo sine wave is input to the A / D converter 9 while having a DC offset. One of the outputs (n bits, n: natural number) of the A / D converter 9 is input to the subtracter 10 and the other is input to the DC offset detection circuit 11.
[0013]
Immediately after the power of the encoder device is turned on, the outputs of the offset detection circuits 8 and 11 hold zero due to the initial reset operation. Therefore, at this time, “zero” is subtracted from the original two-phase pseudo sine wave. That is, the data is transmitted to the subsequent subdivision circuit 5 without any data transmission. Next, after a position displacement equal to or more than a certain specified value occurs, the DC offset detection circuits 8 and 11 automatically calculate the DC offsets of the A-phase pseudo sine wave and the B-phase pseudo sine wave, respectively, by an operation described later. After the DC offset is determined for both the A-phase pseudo sine wave and the B-phase pseudo sine wave, the outputs of the DC offset detection circuits 8 and 11 are simultaneously changed from zero. As a result, the outputs of the two subtracters 7 and 10 have a value obtained by removing the DC offset of the original two-phase pseudo sine wave.
[0014]
The subdivision circuit 5 performs subdivision processing based on the two-phase pseudo sine wave from which the DC offset has been removed. In the subdivision processing, the A-phase pseudo sine wave and the B-phase pseudo sine wave are regarded as sin θ and cos θ, and tan θ is obtained by dividing (sin θ) ÷ (cos θ). That is, the correct sin θ and cos θ from which the DC offset has been canceled are input to the subdivision circuit 5, and the subdivision error is reduced. Based on the division result (quotient), θ = tan ^-1 (Quotient) is converted to obtain θ corresponding to the subdivided position information. The resolution specified for the encoder device determines how finely (sin θ) ÷ (cos θ) is calculated.
[0015]
FIG. 2 is a diagram illustrating a basic principle of detecting a DC offset. It is assumed that the pseudo sine wave has a DC offset in the plus potential direction with respect to the reference potential (reference level) as shown in the figure. Here, if a position displacement of one wavelength or more in a single direction occurs, the peak value and the valley value (valley value) can be treated as the maximum value and the minimum value, respectively. Therefore, by dividing the sum of the peak and the bary by 2, it is possible to approximately obtain the DC offset by a simple arithmetic processing.
[0016]
FIG. 3 is a diagram showing a block diagram of DC offset detection. In the figure, a DC offset detection circuit 8 including only the A-phase pseudo sine wave is shown. Since the DC offset circuit 11 of the B-phase pseudo sine wave has the same configuration, the description is omitted. The A-phase pseudo sine wave having a DC offset is A / D converted by the A / D converter 6. The A / D-converted digital data (n bits) is transmitted to a peak hold circuit 21 and a valid hold circuit 22, where it is constantly monitored. Here, only when a positional displacement in a single direction occurs, the maximum value and the minimum value are obtained, for example, four times by the peak hold function and the variable hold function. These four maximum values and minimum values are averaged and output by averaging circuits 23 and 24 at the subsequent stage, respectively. By averaging, a more stable and reliable maximum value and minimum value are obtained.
[0017]
The averaged maximum value (the average value of the peak values) and the minimum value (the average value of the bary values) are added by the addition circuit 25 at the subsequent stage, and then divided by 2 in the division circuit 26 at the subsequent stage. As described above with reference to FIG. 2, the result (quotient) obtained by dividing by 2 can be approximately treated as a DC offset. That is, the DC offset value 27 is obtained at this point.
[0018]
FIG. 4 is a diagram illustrating a relationship between a state from when the power of the encoder device is turned on to a time when the DC offset cancel function is enabled and a segmentation error. This shows a state where the displacement of the device under test in a single direction continues, the peak hold and the valley hold are each held four times, and then the DC offset is canceled and the segmentation error is reduced. After the offset cancel operation is started at the timing of the reference numeral 28 and the offset removing function becomes effective, high-precision segmentation is performed.
[0019]
Next, an algorithm for obtaining and canceling (correcting) a DC offset value will be described in detail with reference to FIGS. FIG. 5 is a flowchart illustrating the flow of the process. The DC offset detection circuits 8 and 11 are realized by ASICs, and are all configured by logic circuits. FIG. 5 is a flowchart illustrating the flow of the processing of the logic circuit. FIG. 6 is a graph showing an A-phase pseudo sine wave and a B-phase pseudo sine wave used in the following description.
[0020]
First, an outline will be described. The other of the A-phase pseudo sine wave and the B-phase pseudo sine wave monotonically increases or monotonically decreases near the center value (reference level, 1.0 V), and the other pseudo sine wave of the target is level 1 ( When an extreme value is taken at 1.3 V or more or at level 2 (0.7 V) or less, the extreme value is regarded as the maximum value or the minimum value, and the data is held. If this condition is not met, the data will not be officially adopted. This is performed until the device under test moves in a single direction and the A-phase pseudo sine wave and the B-phase pseudo sine wave can be detected for four periods. That is, the process is performed until four maximum values and four minimum values can be obtained. An average value of each of the held maximum value and minimum value totals is obtained, added, and divided by 2 to obtain a DC offset value (correction value).
[0021]
The DC offset value (initial value of zero) of each phase of the A-phase pseudo-sine wave and the B-phase pseudo-sine wave thus obtained is subtracted from the output values of the A / D converters 6 and 9 to cancel the DC offset. That is, the output values of the A / D converters 6 and 9 are corrected with the DC offset value. When data to be adopted forever cannot be acquired, the offset canceller does not operate. That is, the offset values output from the DC offset detection circuits 8 and 11 remain at the initial value of zero. In this case, some abnormality is considered, and this abnormality is reflected in the phase plane error.
[0022]
The flowchart in FIG. 5 shows a case where the maximum value and the minimum value (peak value, bary value) of the A-phase pseudo sine wave are obtained. The same applies to the case where the maximum value and the minimum value (peak value, bary value) of the B-phase pseudo sine wave are obtained. 1.0V ± 0.3V near the reference level is the middle range, the range from 1.3V to 2.0V is the maximum value range, and the range from 0.7V to 0V is the minimum value range.
[0023]
First, in step S1 of STATE: 0, it is determined whether or not the B-phase pseudo sine wave is out of the middle range. If it is off, the process proceeds to step S2 of STATE: 1. If it is not off, it stays at step S1 and waits until it comes off. In step S2, it is determined whether the B-phase pseudo sine wave is within the middle range and the A-phase pseudo sine wave is outside the middle range. That is, in step S2, it is determined whether or not the B-phase pseudo sine wave has entered the middle range from outside the middle range in FIG.
[0024]
If it is determined in step S2 that the B-phase pseudo sine wave is within the middle range and the A-phase pseudo sine wave is outside the middle range, the process proceeds to step S3 of STATE: 2. If a negative determination is made that the B-phase pseudo sine wave is in the middle range and the A-phase pseudo sine wave is out of the middle range, the process waits until the determination becomes affirmative. In step S3, the value of the A-phase pseudo sine wave is set as the initial value of the peak value, and the middle range flag is set for the B-phase pseudo sine wave. The middle range flag sets a flag of-when the B-phase pseudo sine wave has a value lower than the reference level, and sets a + flag when the value is higher than the reference level.
[0025]
In step S4 of STATE: 3, the peak hold of the A-phase pseudo sine wave is started. That is, if the value of the A-phase pseudo sine wave increases, it is always updated with a new value, and if it decreases, the previous value is held. In step S5, it is determined whether or not the B-phase pseudo sine wave has crossed the reference level. If it is determined that the reference level has been crossed, the process proceeds to step S6 of STATE: 4, and exits from STATE: 3.
[0026]
In step S6, it is determined whether or not the B-phase pseudo sine wave monotonically increases or monotonically decreases and exits the middle range from the side opposite to the + side or the-side set in the middle range flag. If it is determined that it has come out, the process proceeds to step S7 of STATE: 5. If it is determined that it has not come out yet, it waits until it stops at step S6. When obtaining the peak value, the range of the A-phase pseudo sine wave between STATE: 2 and STATE: 4 is the maximum value adoption range. When obtaining the barrier value, the range of the A-phase pseudo sine wave of STATE: 2 to STATE: 4 is the minimum value adoption range.
[0027]
In step S7, the peak hold (including the hold of the barrier value) of the A-phase pseudo sine wave is ended, and the peak value or barrier value is latched. The middle range flag of the B-phase pseudo sine wave is reset, and the counter is incremented. This counter is incremented every time the peak value and the barrier value of the A-phase pseudo sine wave are obtained. In step S8, it is determined whether the counter value has reached 8. If it is determined that the count has not yet been counted up to 8, the process is repeated from step S1 of STATE: 0. If it is determined that the counter value has reached 8, the processing is terminated. When the processing is completed, the maximum value and the minimum value of the A-phase pseudo sine wave are obtained four by eight, that is, a total of eight values are held in the latch circuit.
[0028]
On the other hand, in STATE: 3, the AND circuit 31 takes an AND (product) of the STATE: 3 and the B-phase pseudo sine wave inversion area outside signal 32 to generate a RESET1 signal. The B-phase pseudo sine wave inversion area outside signal 32 monitors the B-phase pseudo sine wave, and the B-phase pseudo sine wave leaves the middle range from the same side as the + side or the − side set in the middle range flag. This signal is set in the case. In other words, this is the case where the B-phase pseudo sine wave exits on the same side as the one entering the middle range before crossing the reference level. This means that the movement of the object to be measured is reversed before the B-phase pseudo sine wave crosses the reference level. At this time, a RESET1 signal is generated, and the process returns to step S1 of STATE: 0.
[0029]
Also, in STATE: 4, the AND circuit 33 takes an AND (product) of the STATE: 4 and the B-phase pseudo sine wave inversion area out-of-range signal 32 to generate a RESET2 signal. In this case, the B-phase pseudo sine wave does not escape from one side of the middle range to the other side while increasing or decreasing monotonously, and exits on the same side as the side that entered the middle range. This means that the movement of the object to be measured has been reversed before the B-phase pseudo sine wave crossed the reference level and passed through the middle range. At this time, a RESET2 signal is generated, and the process returns to step S1 of STATE: 0.
[0030]
At STATE: 5, the XNOR circuit 34 calculates the XOR (negation of exclusive OR) of the peak value or bary value sign 35 of the previously obtained A-phase pseudo sine wave and the currently obtained peak value or bary value sign 36 at the XNOR circuit 34. take. If the codes match, a RESET3 signal is generated. If the codes do not match, no RESET3 signal is generated. The sign referred to here is a plus sign when the peak value is larger than the reference level, and a minus sign when the bary value is smaller than the reference level. If the signs do not match, it means that the device under test is moving in a single direction. If the signs match, it means that the peak value was detected this time in the case of the previous peak value, and that the validity value was also detected this time in the case of the previous valid position. In other words, it means that the measured object has reversed and moved after detecting the peak value or the bary position.
[0031]
The RESET1, RESET2, and RESET3 signals all reset the counter circuit, the maximum and minimum value latch circuits, the middle range flag, and the like. That is, the sequence for determining the maximum value and the minimum value of the A-phase pseudo sine wave is reset, and the process is restarted from the beginning. The reset also operates when the power of the encoder device is turned on.
[0032]
The four maximum values of the A-phase pseudo sine wave thus obtained are averaged by the averaging circuit 23, and the four minimum values are averaged by the averaging circuit 24 to add the two average values. The addition is performed by the circuit 25 and the division is performed by 2 in the division circuit 26 to obtain a DC offset value (correction value) of the A-phase pseudo sine wave. The DC offset value (correction value) obtained in this way is subtracted by the subtractor 7 from the output value of the A / D converter 6 to cancel the DC offset. That is, the output value of the A / D converter 6 is corrected with the DC offset value. The DC offset value (correction value) of the B-phase pseudo sine wave is similarly obtained, and the output value of the A / D converter 9 is corrected with the DC offset value.
[0033]
The encoder device according to the present embodiment described above has the following effects.
(1) It is possible to automatically cancel the DC offset of the analog pseudo sine wave of the encoder device without requiring manual adjustment by a special external variable resistor. As a result, it is possible to reduce the segmentation error and improve the position detection accuracy. When applied to a control system using an encoder device, it contributes to reduction of deviation in position control, that is, improvement of characteristics in position control. Further turning to the AC characteristics, the difference between the position information of the encoder device that changes every moment is the speed information itself. In other words, there is an advantage that the improvement in the position accuracy of the encoder device contributes to suppression of deviation in speed control, that is, speed unevenness (speed ripple).
(2) Since the two-phase pseudo sine wave from which the DC offset has been canceled is input to the subdivision circuit, the subdivision error caused by the DC offset can be reliably reduced.
(3) When calculating the peak value or the barrier value, when the other pseudo sine wave monotonically increases or decreases from the predetermined level 1 to the predetermined level 2 across the reference level, the extreme value acquired during that time is set to the maximum value or Data is held assuming the minimum value. When the other pseudo sine wave crosses the zero cross or the reference level, a more accurate peak value or a valid value can be obtained as compared with a case where the value at that time is regarded as a maximum value or a minimum value. Further, it is possible to reliably eliminate the case where the measured object reaches the peak value due to the reversal movement. That is, it is possible to reliably detect the peak value or the barrier value when the device under test is moving in a single direction without being inverted.
(4) Since the DC offset value is obtained after obtaining the peak value and the barrier value in a plurality of cycles, a more reliable DC offset value can be obtained. For example, it is possible to reduce the influence of a case where dust is present in the slit of the rotating disk 3 or a case where a defect such as a scratch occurs. Further, the influence of disturbance such as noise can be reduced.
(5) In the above description, the plurality of cycles is four, but any number of two or more may be used. In this case, a value of 2 to the power of n such as two periods or eight periods is more preferable. This is because calculations such as addition and averaging are easy to do.
(6) The plurality of periods are a plurality of periods that can be acquired while the device under test moves in a single direction that does not include inversion. As a result, a highly accurate DC offset value can be obtained.
(7) After acquiring the peak value and the barrier value for a plurality of predetermined periods, the A-phase pseudo sine wave and the B-phase pseudo sine wave are simultaneously corrected with the obtained DC offset value. As a result, it is possible to output a highly accurate two-phase pseudo sine wave in which the DC offset value is surely canceled from a certain timing. As a result, highly accurate segmentation processing is reliably performed from a certain timing, and highly accurate position information can be obtained.
(8) Since the reset is performed every time the power of the encoder device is turned on, a correction value that is a DC offset value is newly obtained each time the power is turned on. As a result, it is possible to reliably cope with the aging of the encoder device, and to obtain highly accurate position information.
[0034]
In the above-described embodiment, an example of the encoder device that determines the rotational position of the motor has been described. However, the present invention is not necessarily limited to this. An encoder device for obtaining a linear position may be used. That is, it can be applied to any encoder device.
[0035]
In the above embodiment, the DC offset detection circuits 8 and 11 have been described as examples of the logic circuit using the ASIC, but it is not necessarily limited to this content. It may use a micro CPU or the like. In that case, the above-described processing of FIG. 5 is executed by a program.
[0036]
In the above embodiment, the method (tan) using the arctangent function as the subdivision circuit 5 ^-1 θ method), but it is not necessarily limited to this content. A subdivision circuit using a method of subdivision using a resistor array or another method may be used.
[0037]
In the above embodiments, various embodiments and modified examples have been described, but the present invention is not limited to these contents. Other embodiments that can be considered within the scope of the technical idea of the present invention are also included in the scope of the present invention.
[0038]
【The invention's effect】
Since the present invention is configured as described above, it has the following effects. In a periodic signal used for measurement, detection of a peak value or the like due to reverse movement of the device under test is reliably excluded, and a more accurate peak value or barrier value can be reliably detected. Further, a highly reliable correction value of the periodic signal can be obtained. For example, when dust is present in the slit of the rotating disk or when a defect such as a scratch occurs, the influence of disturbance such as noise can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram of an encoder device showing one embodiment of a measuring device of the present invention.
FIG. 2 is a diagram illustrating a basic principle of detecting a DC offset.
FIG. 3 is a diagram showing a block diagram of DC offset detection.
FIG. 4 is a diagram illustrating a relationship between a state from when the encoder device is powered on until a DC offset cancel function is enabled and a segmentation error.
FIG. 5 is a flowchart illustrating a processing flow of a DC offset detection circuit.
FIG. 6 is a graph showing an A-phase pseudo sine wave and a B-phase pseudo sine wave used for describing the flow of processing of the DC offset detection circuit.
[Explanation of symbols]
1 Light-emitting element
2 Light receiving element
3 rotating disc
4 Amplifier circuit
5 Subdivision circuit
6, 9 A / D converter
7, 10 Subtractor
8,11 DC offset detection circuit
21 Peak hold circuit
22 Bali Hold Circuit
23, 24 Averaging circuit
25 Addition circuit
26 Division circuit

Claims (6)

The first periodic signal and the second periodic signal having a phase difference of substantially 90 degrees and having the same period detected along with the movement of the device under test are used for the first periodic signal. In a measuring device that detects the peak value of a signal,
Signal acquisition means for acquiring the first periodic signal and the second periodic signal;
When the acquired second periodic signal monotonically increases or decreases from a first predetermined value to a second predetermined value across a predetermined reference level of the second periodic signal, A peak value detecting means for detecting a peak value of the first periodic signal obtained as a peak value while the device under test is moving in a single direction. Position information of the device under test using the first and second periodic signals having a phase difference of substantially 90 degrees and having the same period detected as the device under test moves. In a measuring device that acquires
First correction value detection means for obtaining a first correction value of the first periodic signal;
First correction means for correcting the first periodic signal based on the obtained first correction value;
Second correction value detection means for obtaining a second correction value of the second periodic signal;
A second correction unit that corrects the second periodic signal based on the obtained second correction value;
Based on the corrected first periodic signal and the corrected second periodic signal, performing subdivision processing to obtain subdivided position information of the DUT. Prepare,
The first correction value detection means may be configured such that the second periodic signal monotonically increases between a first predetermined value and a second predetermined value across a predetermined reference level of the second periodic signal. When one of the peak value and the bary value of the first periodic signal during that period is obtained, and when the value monotonously decreases between the first predetermined value and the second predetermined value, the first period during the period is obtained. Obtaining the other of the peak value or the bary value of the target signal, obtaining the first correction value based on the obtained peak value and the bary value of the first periodic signal,
The second correction value detecting means may be configured such that the first periodic signal monotonically increases between a third predetermined value and a fourth predetermined value across a predetermined reference level of the first periodic signal. At this time, one of the peak value or the bary value of the second periodic signal during that time is obtained, and when the value monotonically decreases between the third predetermined value and the fourth predetermined value, the second periodic signal during that time is obtained. A measuring apparatus for acquiring the other of the peak value and the bary value, and obtaining the second correction value based on the obtained peak value and the bary value of the second periodic signal. Position information of the device under test using the first and second periodic signals having a phase difference of substantially 90 degrees and having the same period detected as the device under test moves. In a measuring device that acquires
First correction value detection means for obtaining a first correction value of the first periodic signal;
First correction means for correcting the first periodic signal based on the obtained first correction value;
Second correction value detection means for obtaining a second correction value of the second periodic signal;
A second correction unit that corrects the second periodic signal based on the obtained second correction value;
Based on the corrected first periodic signal and the corrected second periodic signal, performing subdivision processing to obtain subdivided position information of the DUT. Prepare,
The first correction value detection means acquires the peak value and the bary value for at least two cycles while the device under test is moving in a single direction, and acquires the peak value and the peak value of the acquired first periodic signal. Calculating the first correction value based on the bary value, outputting the obtained first correction value to the first correction unit,
The second correction value detection means acquires the peak value and the bary value of the at least two cycles in synchronization with the first periodic signal while the device under test moves in the single direction, Measuring the second correction value based on the peak value and the bary value of the obtained second periodic signal, and outputting the obtained second correction value to the second correction unit; apparatus. The measuring device according to claim 3,
The first correction value detection means does not output the first correction value or outputs a zero correction value until the peak value and the bary value for at least two cycles are obtained,
The measurement apparatus according to claim 2, wherein the second correction value detecting means does not output the second correction value or outputs zero correction value until the peak value and the barrier value for at least two cycles are obtained. The measuring device according to any one of claims 3 to 4,
The measurement device according to claim 1, wherein the at least two cycles are cycles of a power of two. The measuring device according to any one of claims 3 to 5,
The measuring device is characterized in that the counting for at least two cycles is performed when the power of the measuring device is turned on.

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