JP4900473B2 - Absolute value encoder device and multi-rotation detection method - Google Patents

Description

  The present invention relates to an absolute value encoder that detects the rotational position of a servo motor used in a robot, an NC machine tool, and the like, and more particularly, an absolute value encoder device capable of detecting a multi-rotation amount when a power supply is cut off and maintaining the absolute position, and multi-rotation It relates to a detection method.

  In an encoder used in a conventional robot or the like, a battery backup is performed in order to detect a multi-rotation amount and maintain an absolute position when the power is shut off (see, for example, Patent Document 1).

  FIG. 8 is a block diagram of a conventional multi-rotation absolute encoder device.

  This multi-rotation absolute encoder device includes a detection unit 21, a waveform shaping unit 22 that shapes a detection signal from the detection unit 21, and an MSB (most significant bit) among code signals output from the waveform shaping unit 22, And MSB-1 (the next most significant bit) bit signal is supplied to the multi-rotation counting unit 23 that counts the multi-rotation number, the detection unit 21, the waveform shaping unit 22, and the multi-rotation counting unit 23. A main power source 24 and a backup power source 25 for supplying a backup power source to the multi-rotation counting unit 23 are provided. Further, the main power shut-off state also includes a counting signal storage unit 26 that retains data by the backup power source 25. Based on the state of the counting signal storage unit 26 and the state of the same signal when the main power is turned on, multiple rotations are provided. And a rotation detector 28 for correcting the count value of the counter.

  Next, the operation will be described.

  FIG. 9 is a diagram for explaining the operation of a conventional multi-rotation absolute encoder device.

  The signals MSB and MSB-1 for multi-rotation counting are signals that are out of phase by a quarter period, and the combination of the “H” and “L” states of two signals within one period is 4 Can be divided into two states. When motion detection is performed only for a minute rotational motion when the main power is turned off, if the difference between the four states can be detected, the motion within one rotation can be detected.

  Stores the “H” and “L” states of the MSB and MSB-1 signals just before the main power is turned off, and compares the two signals before and after the main power is turned off, so that only slight movements within a quarter of a turn are possible. Limited correction of the multi-turn count value is performed.

  The “H” and “L” states of the MSB and MSB-1 signals immediately before the main power supply is turned off are stored in the storage element. For example, the encoder moves slightly when the main power supply is turned off. Suppose that it has changed. In the state A, the MSB is “H” and the MSB-1 is “L”. When this is changed to the state B, the MSB is “L” and the MBS-1 is “L”. And B can be detected to have moved.

  As shown in FIG. 9, if the count switching is performed at the start point of “1” and the end point of “4”, the number of rotations is not switched when MBS-1 is “H”. When MSB-1 is “L” and the MSB is changed from “H” to “L”, it means that “4” is changed to “5”, and the rotation speed is added for correction. On the contrary, when MSB-1 is “L” and MSB is changed from “L” to “H”, it means that “5” is changed to “4”, and the rotation number is subtracted for correction.

As described above, the conventional multi-rotation absolute encoder device monitors the state of the multi-rotation counting signal before the main power supply is shut off and when the main power supply is turned on again, and limits the subtle movement during the main power supply shut-off. The count value was corrected.
Japanese Patent Laid-Open No. 9-218054

  However, in the case of application to robots, the conventional multi-rotation absolute encoder device assumes that the motor does not move due to a brake or the like when the main power is cut off. Only the shift due to a subtle position change when the main power is turned on again is corrected. Actually, in the case of a brake failure, the position changes due to the drop of the arm due to gravity, and the multi-rotation amount may change. Also, when the main power is turned off, the motor may be rotated by an external force and the multi-rotation amount may change. Furthermore, when an instantaneous power failure occurs during operation, the amount of multi-rotation may change beyond the limit value that can be corrected if the motor rotates at high speed. In these cases, there is a problem in maintainability because the initialization work occurs again.

  Conventionally, when the main power supply is shut off, the battery power supply is used to supply power to the multi-rotation amount detection unit to detect the multi-rotation amount. However, it is required to reduce the power consumption of the battery power as much as possible.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an absolute value encoder device and a multi-rotation detection method that have good maintainability and low power consumption during battery power supply.

  In order to solve the above problems, the present invention is configured as follows.

That is, an absolute value encoder according to one aspect of the present invention includes a multi-rotation detection sensor unit that includes at least two magnetic field detection elements and detects a multi-rotation amount of a rotating body, and a drive unit that drives the magnetic field detection element. A position sensor for detecting position within one rotation for detecting a position within one rotation of the rotating body, and a two-phase multi-rotation detection signal output from the sensor section for detecting multi-rotation is converted into a rectangular wave through a comparator; A multi-rotation amount calculation unit that calculates a multi-rotation amount from the multi-rotation signal converted into the rectangular wave, and a single-rotation position detection signal output from the single-rotation position detection sensor unit are acquired through an AD converter. A single-rotation position calculation unit that calculates an absolute position within a rotation, a power supply switching unit that switches between a main power source and a battery power source and supplies battery power when the main power source is shut off, and the absolute position within one rotation and the multi-rotation amount are combined. In the absolute value encoder device including an absolute position generation unit that generates an absolute position, the multi-rotation amount calculation unit includes a first multi-rotation amount calculation unit that calculates a multi-rotation amount when the main power is supplied, and a battery power source. A second multi-rotation amount calculation unit for calculating a multi-rotation amount at the time of supply; and a state of the multi-rotation signal immediately before power switching and immediately after power switching at the time of switching between the main power supply and the battery power supply And a multi-rotation amount correcting unit that corrects an initial value of the multi-rotation amount after switching.

In the absolute value encoder according to the above aspect, the drive unit may supply a pulsed power supply having a constant cycle to the magnetic field detecting element when battery power is supplied .

The absolute value encoder according to the above aspect may be characterized in that the drive unit switches the pulse cycle of the pulsed power supply according to the rotation speed of the rotating body when battery power is supplied .

The absolute value encoder according to the first aspect may be characterized in that the pulse width of the pulsed power supply can be set according to the rising and falling characteristics of the multi-rotation signal when battery power is supplied .

On the other hand, a multi-rotation detection method for an absolute encoder according to another aspect of the present invention includes a multi-rotation detection sensor unit that includes at least two magnetic field detection elements and detects a multi-rotation amount of a rotating body, and the magnetic field detection element. A driving unit that drives the rotary body, a sensor unit for detecting a position within one rotation for detecting a position within one rotation of the rotating body, and a two-phase multi-rotation detection signal output from the sensor unit for detecting multi-rotation through a comparator. A multi-rotation amount calculation unit that converts a multi-rotation signal from the multi-rotation signal that has been converted into a rectangular wave and calculates a multi-rotation amount from the multi-rotation signal converted into the rectangular wave; A position-in-rotation position calculation unit that takes in through an AD converter and calculates an absolute position in one rotation, a power source switching unit that switches between a main power source and a battery power source and supplies battery power when the main power source is shut off, and the absolute position in one rotation in front In the multi-rotation detection method of the absolute value encoder apparatus including the absolute position generation unit that synthesizes the multi-rotation amount and generates an absolute position, the multi-rotation amount calculation unit calculates the first rotation amount when the main power is supplied. And a second multi-rotation amount calculation unit that calculates the multi-rotation amount when battery power is supplied, and the first multi-rotation amount calculation unit calculates the multi-rotation amount when main power is supplied. The second multi-rotation amount calculation unit calculates the multi-rotation amount at the time of battery power supply, and the state of the multi-rotation signal immediately before power switching and immediately after power switching at the time of switching between main power supply and battery power supply. It is characterized by acquiring and correcting the initial value of the multi-rotation amount after power switching.

According to the absolute value encoder according to one aspect of the present invention, the multi-rotation amount is calculated even when the main power supply is shut off, and the multi-rotation amount is corrected based on the state of the multi-rotation signal before and after the power switch when the power is switched. Even if a change occurs in the multi-rotation signal before and after the power supply switching, the multi-rotation amount can be calculated without any calculation error within a predetermined range, and an absolute value encoder apparatus with good maintainability can be realized.

In addition, according to the absolute value encoder according to the above aspect , the multi-rotation detection magnetic field detecting element is intermittently driven when the battery power is supplied, so that the power consumption when the battery power is supplied can be further reduced.

In addition, according to the absolute value encoder according to the above aspect 1, if the cycle of intermittent driving when battery power is supplied is set in accordance with the rotational speed of the motor, optimal intermittent driving according to the rotational speed can be achieved, further reducing power consumption. it can.

In addition, according to the absolute value encoder according to the above-mentioned one aspect, the power supply time in the intermittent drive at the time of battery power supply is the characteristics of the hard circuit such as the magnitude of the multi-rotation detection signal or the solid difference in the rise time by the comparator or the hardware circuit. If the setting is taken into consideration, power can be supplied according to the characteristics of the multi-rotation detection signal, and the power consumption can be further reduced.

Further , according to the multi-rotation detection method of the absolute value encoder device according to another aspect of the present invention, the multi-rotation amount is calculated even when the main power is shut off, and the multi-rotation amount is calculated based on the state of the multi-rotation signal before and after the power switch when the power is switched. Since the rotation amount is corrected, even if a change occurs in the multi-rotation signal before and after the power supply is switched, the multi-rotation amount can be calculated without any calculation error within a predetermined range, and the reliability of the multi-rotation amount calculation is improved.

The block diagram which shows the structure of the absolute value encoder apparatus in 1st Example of this invention. The figure which shows the relationship between the multiple rotation signal in 1st Example of this invention, and the absolute position within 1 rotation. The flowchart which shows the operation | movement of multiple rotation amount correction | amendment in 1st Example of this invention. The block diagram which shows the structure of the absolute value encoder apparatus in 2nd Example of this invention. Operation waveform diagram of multi-rotation signal during intermittent driving in the second embodiment of the present invention The time chart which shows the operation | movement in 2nd Example of this invention, The example in case the count-up position has advanced at the time of battery power supply compared with the time of main power supply The time chart which shows the operation | movement in 2nd Example of this invention, The example in case the count-up position is late | slow compared with the time of main power supply at the time of battery power supply Block diagram of a conventional multi-turn absolute encoder device The figure for demonstrating operation | movement of the conventional multi-rotation absolute encoder apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor part for multi-rotation detection 2 Drive part 3 Main power supply 4 Battery power supply 5 Power supply switching part 6 Sensor part for position detection within one rotation 7 AD converter 8 Position calculation part within one rotation 9 Comparator 10 Multi-rotation amount calculation part 11 Absolute Position generation unit 12 First multi-rotation amount calculation unit 13 Second multi-rotation amount calculation unit 14 Multi-rotation amount correction unit 15 Intermittent operation drive unit 21 Detection unit 22 Waveform shaping unit 23 Multi-rotation counting unit 24 Main power supply 25 Backup power source 26 Counting signal storage unit 28 Rotation detection unit

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

  FIG. 1 is a block diagram showing a configuration of an absolute value encoder apparatus according to a first embodiment of the present invention.

  In the figure, reference numeral 1 denotes a multi-rotation detection sensor unit, which is composed of a permanent magnet fixed to a rotating body (not shown) and a magnetic field detection element attached to the fixed body via a gap. 2 is a drive unit that supplies and drives power to the magnetic field detection element, 3 is a main power source, 4 is a battery power source, 5 is a power source switching unit that switches between the main power source and the battery power source, 6 is a sensor unit for position detection within one rotation, 7 Is an AD converter that takes in a detection signal within one rotation from a sensor unit for detecting position within one rotation and converts it into digital data, 8 is a position calculation unit within one rotation that takes an AD conversion result and calculates an absolute position within one rotation, 9 Is a comparator that converts a multi-rotation detection signal from two magnetic field detection elements having different phases into a multi-rotation signal of a rectangular wave, 10 is a multi-rotation amount calculation unit that takes in the multi-rotation signal and calculates a multi-rotation amount, and 11 is 1 This is an absolute position generator that combines the absolute position in rotation and the amount of multiple rotations to obtain an absolute position.

  The multi-rotation amount calculation unit 10 includes a first multi-rotation calculation unit 12 that calculates the multi-rotation amount when the main power is supplied, a second multi-rotation calculation unit 13 that calculates the multi-rotation amount when the battery power is supplied, It comprises a multi-rotation amount correction unit 14 that acquires the state of a multi-rotation signal immediately before and after power switching at the time of switching between power supply and battery power supply and corrects the multi-rotation amount after power switching.

  The magnetic field detection element of the multi-rotation detection sensor unit 1 is composed of two elements having different phases as long as it can output a multi-rotation signal of one cycle for one rotation made a rectangular wave by a comparator. The sensor unit for detecting the position within one rotation may be a magnetic or optical sensor that can detect the absolute position within one rotation. In the case of a magnetic system, switching between detection for one rotation and detection for multiple rotations may be performed, and detection within one rotation and multiple rotation detection may be combined.

  Next, the multi-rotation detection operation of the absolute value encoder apparatus according to the first embodiment of the present invention will be described.

  When the power supply switching unit 5 detects that the main power supply is shut off, the power supply switching unit 5 outputs a switching signal to the multi-rotation amount calculation unit 10 and switches the power supply from the main power supply to the battery power supply.

  The operation is roughly divided into three. That is, the operation during main power supply in which the position within one rotation and the amount of multi-rotation are calculated, the operation during battery power supply in which only the calculation of the multi-rotation amount is performed, and the operation at the time of switching between the main power source and the battery power source is there.

  Hereinafter, these operations will be described in order.

(Operation during main power supply)
First, the operation during the main power supply will be described.

  FIG. 2 is a diagram showing the relationship between the multi-rotation signal and the absolute position within one rotation in this embodiment. When the main power is supplied, power is supplied to the entire encoder device. In the figure, M1 and M0 are two-phase multi-rotation signals output from the comparator 9. The relationship between M1 and M0 is such that the multi-rotation detection sensor unit 1 and the comparator 9 are designed so as to be a rectangular wave having a 90-degree phase difference and HI and LO levels of 50% duty. Further, in order to easily understand the relationship between the multi-rotation signal and the absolute position within one rotation, a configuration in which the M1 signal changes at the origin of the absolute position within one rotation is desired. A deviation from the position may be considered as a correction value. In the present embodiment, the M1 signal changes at the origin of the absolute position within one rotation.

  When the main power is supplied, the multi-rotation signals M1 and M0 are taken into the first multi-rotation amount calculation unit 12. During forward rotation, counting is performed when the rising edge of the M1 signal and the M0 signal is LO, and during reverse rotation, counting is performed when the falling edge of the M1 signal and the M0 signal is LO.

(Operation during battery power supply)
Next, the operation during battery power supply will be described.

  At the time of battery power supply, power is supplied only to the portion for calculating the multi-rotation amount, that is, the multi-rotation detection sensor unit 1, the comparator 9, and the multi-rotation amount calculation unit 10.

  When the battery power is supplied, the multi-rotation signals M1 and M0 are taken into the second multi-rotation amount calculation unit 13. During forward rotation, counting is performed when the rising edge of the M1 signal and the M0 signal is LO, and during reverse rotation, counting is performed when the falling edge of the M1 signal and the M0 signal is LO.

  Use a microcomputer with low power consumption function such as sleep mode for multi-rotation calculation, and use the interrupt function by the edge of the signal during low power consumption operation, that is, count up and down at the signal edge To do. The microcomputer returns from the sleep mode at the time of interruption or periodically, and shifts to the sleep mode upon completion of calculation.

  However, if such an interrupt function is not provided, the M1 and M0 signals are periodically monitored, and during forward rotation, the M1 signal changes from LO to HI and the M0 signal counts up when it is LO. At the time of reverse rotation, it is only necessary to count down when the M1 signal changes from HI to LO and the M0 signal is LO.

(Operation when switching power)
Next, the operation at the time of power switching will be described.

  At the time of switching between the main power supply and the battery power supply, the multi-rotation amount correction unit 14 is configured so that a normal multi-rotation amount can be obtained even if a position change occurs in the multi-rotation signal due to a difference in power supply conditions between the main power supply and the battery power supply. To correct the multi-rotation amount.

  When the power is switched, a switching signal is output from the power switching unit 5 to the multi-rotation amount correcting unit 14. When switching from the main power supply to the battery power supply, the first multi-rotation amount calculation unit 12 acquires the states of the multi-rotation signals M1 and M0 immediately before the main power supply is cut off, that is, M1Last and M0Last. Next, the second multi-rotation amount calculation unit 13 acquires the states of the multi-rotation signals M1 and M0 immediately after the battery power supply, that is, M1Now and M0Now, and the multi-rotation amount correction unit 14 determines the change in the state of these signals. Correct the amount of multi-rotation at the start of battery power.

  Conversely, when switching from the battery power supply to the main power supply, the states of the multi-rotation signals M1 and M0 immediately before the battery power supply is cut off are acquired as M1Last and M0Last. Next, the states of the multi-rotation signals M1 and M0 immediately after the main power supply is acquired as M1Now and M0Now, and the multi-rotation amount at the start of the main power supply is corrected by the change in the state of these signals.

  FIG. 3 is a flowchart showing the multi-rotation amount correction operation in the first embodiment of the present invention.

  A case where the main power source is switched to the battery power source will be described as an example.

When the main power supply drops below a predetermined voltage and a switching signal is output from the power supply switching unit 5 to the multi-rotation amount calculation unit 10,
In step 1, the first multi-rotation amount calculation unit 12 takes in M1Last and M0Last,
Immediately after that, in step 2, the power source switching unit 5 switches from the main power source to the battery power source.

  When the power source is switched, in step 3, the second multi-rotation amount calculation unit 13 captures M1Now and M0Now immediately after the power source switching.

  Next, in Step 4, the multi-rotation correction unit 14 determines whether or not M0Now = LO.

  If YES, in step 5, it is further determined whether M1Last = LO and M1Now = HI. If YES, that is, if YES in step 4 and step 5, M0Now = LO and M1Last = LO and M1Now. In the case of = HI, since the count-up position has been crossed by normal rotation, the multi-rotation amount is incremented by 1 (step 6), and then limit processing (step 9) is performed and the process is terminated.

  If NO in step 5, it is further determined in step 7 whether M1Last = HI and M1Now = LO. In the case of YES, since the countdown position has been crossed by reverse rotation, the multi-rotation amount is decremented by 1 (step 8), and then limit processing (step 9) is performed and the process is terminated.

  Further, in the case of NO in step 4 and step 7, limit processing (step 9) is performed and the process is terminated.

  The limit processing is processing for overflow when the amount of multi-rotation exceeds the limit value of the counter or falls below zero.

  When the main power supply is restored and the battery power supply is switched to the main power supply, the second multi-rotation amount calculation unit 13 captures M1Last and M1Last, and the first multi-rotation amount calculation unit 12 captures M1Now and M0Now. However, since the correction operation is the same, the description thereof is omitted.

  When the main power supply state is obtained by power switching, the corrected multi-rotation amount obtained from the first multi-rotation amount calculation unit 12 is set as an initial value, and the absolute value generation unit 11 calculates the absolute position within one rotation. The absolute position within one rotation obtained from the unit 8 is synthesized and the absolute position is output. The subsequent increase / decrease of the multi-rotation amount during the main power supply may be a count by passing the origin of the absolute position within one rotation, or may be a count by the first multi-rotation amount calculation unit 12.

  Thus, in this embodiment, when the main power source and the battery power source are switched, the multi-rotation signal immediately before and immediately after the switching is detected, and the multi-rotation amount is corrected from the state of the multi-rotation signal immediately before and immediately after the switching. Even if there is a difference in the multi-rotation signal due to power supply conditions or circuit conditions or a delay in taking in the multi-rotation signal due to the operation mode switching process of the microcomputer, the multi-rotation amount counting error can be eliminated if it is within a predetermined error, Accurate absolute position data can be detected.

  In addition, power saving of the battery power source can be realized by operating the microcomputer in the sleep mode. For example, when the main power is supplied, it is necessary to detect the multi-rotation amount at high speed rotation, and the multi-rotation amount is calculated by detecting the edge of the M1 signal. However, when the battery power is supplied, the power consumption of the multi-rotation amount calculating unit is suppressed. Therefore, it is a general practice to calculate the multi-rotation amount by operating the microcomputer used in this circuit in the sleep mode and detecting the states of the M1 signal and the M0 signal at a constant period. In this case, a time lag of the detection signal due to a difference in circuit conditions or a microcomputer operation mode switching process occurs, but a multi-rotation amount counting error can be eliminated if it is within a predetermined range.

  FIG. 4 is a block diagram showing the configuration of the absolute value encoder apparatus in the second embodiment of the present invention.

  In the figure, 15 is an intermittent operation drive unit that supplies pulsed power to the multi-rotation detection sensor unit 1 when battery power is supplied. The difference from the configuration of the first embodiment is that an intermittent operation drive unit is provided. In the present embodiment, during battery power supply, power supply to the multi-rotation detection sensor unit is intermittent.

  Next, the multi-rotation detection operation of the absolute value encoder apparatus in the present embodiment will be described.

  Similar to the first embodiment, the operation is roughly divided into three. That is, the operation during the main power supply in which the absolute position within one rotation and the multi-rotation amount are calculated, the operation during the backup power supply in which only the multi-rotation amount is calculated, and the operation at the time of switching between the main power source and the backup power source It is.

  Hereinafter, these operations will be described in order.

(Operation during main power supply)
Since the operation during the main power supply is the same as that of the first embodiment, the description thereof is omitted.

(Operation during battery power supply)
Next, the operation during battery power supply will be described.

  At the time of battery power supply, power is supplied only to the portion that calculates the multi-rotation amount as in the first embodiment. In this embodiment, the multi-rotation magnetic field detection element further receives a signal from the power switching unit 5. In response to this, the intermittent operation drive unit 15 is driven for a fixed time every fixed period.

  That is, the supply of power to the magnetic field detection element (not shown) of the multi-rotation detection sensor unit 1 is started when the timer counts for a certain period. After a lapse of a certain time from the power supply, the multi-rotation signals M1 and M0 are taken into the second multi-rotation amount calculation unit 13, and the power supply is stopped.

  A microcomputer with low power consumption function such as sleep mode is used for multi-rotation calculation. It returns from the sleep mode at the start of power supply, but after calculating the signal and stopping the power supply, the calculation operation is performed.

  Here, the operation waveforms of the multi-rotation signals M1 and M0 during intermittent driving will be described.

  During intermittent driving, a certain amount of time is required until the output of the comparator rises and the multi-rotation signals M1 and M0 output as rectangular waves become steady.

  FIG. 5 is an operation waveform diagram of the multi-rotation signal at the time of intermittent driving in the present embodiment, and FIG. 5 (a) shows a case where the time until the multi-rotation signals M1 and M0 are taken after the power supply is started is long. In this case, since sufficient time has passed, the multi-rotation signal is in a steady state, and the ratio between the HI and LO sections of the multi-rotation signals M1 and M0 is 50%: 50%.

  FIGS. 5B and 5C show a case where the time until capturing is short. Before supplying power to the multi-rotation detection sensor unit 1, the output from the comparator is in an indefinite state. When the time to capture is shortened, the ratio between the HI and LO intervals of the multi-rotation signals M1 and M0 captured is different from 50%: 50% depending on whether the comparator output before power supply is HI or LO. Come. (B) shows the case where both M1 and M0 are in the HI state before the power supply, and the ratio of the HI and LO sections becomes HI> LO, and (c) both the M1 and M0 are in the LO state before the power supply. In this case, the ratio between the HI and LO sections is HI <LO.

  For this reason, since the rising and falling positions of the signal are shifted, the count-up and count-down positions are also shifted.

  However, even if the rising and falling positions are deviated, (M1, M0) is once per rotation, and during forward rotation, (HI, LO) → (HI, HI) → (LO, HI) → (LO, LO) In reverse rotation, if there are four consecutive states (LO, LO) → (LO, HI) → (HI, HI) → (HI, LO), and if the four states are output repeatedly according to the rotation, During forward rotation, the M1 signal changes from LO to HI and the M0 signal counts up when LO, and during reverse rotation, the M1 signal changes from HI to LO and counts down when the M0 signal is LO. That is, the counter is counted up or down once per rotation and is counted normally. By setting the power supply time to a time that satisfies this condition, a significant reduction in current consumption can be realized.

(Operation when switching power)
In the present embodiment, the intermittent operation drive unit 15 drives the magnetic field detection element for multiple rotations for a certain period of time (supplys a pulsed power supply) at a certain period by a signal from the power supply switching unit 5. In this way, when the power supply time is short, the rising and falling positions of the multi-rotation signal are likely to shift. The processing operation at the time of switching the power supply is the same as that of the first embodiment, and is represented by the flowchart of FIG. 3 used for the description of the first embodiment. The operation at the time of power supply switching when the falling position is shifted will be described in more detail using a time chart.

  FIG. 6 is a time chart showing the operation in this embodiment, which is an example in which the count-up position is advanced when the battery power is supplied compared to when the main power is supplied.

FIG. 6A is a time chart when switching from the main power supply to the battery power supply. M1Last = LO and M0Last = LO are detected at time t− ₁ immediately before the power supply switching, and M1Now = at time t _{+ 1} immediately after the power supply switching. This is a case where HI is detected. In this case, +1 is corrected. FIG. 6B is a time chart when the battery power source is switched to the main power source. M1 Last = HI and M0 Last = LO are detected at time t− ₁ immediately before the power source switching, and at time t _{+ 1} immediately after the power source switching. This is a case where M1Now = LO is detected. In this case, −1 is corrected. Thereafter, +1 is counted when M1 changes from LO to HI (t _{+ 1} ′).

  FIG. 7 shows an example in which the count-up position is delayed when battery power is supplied compared to when main power is supplied, contrary to FIG.

FIG. 7A is a time chart when the main power source is switched to the battery power source. M1Last = HI and M0Last = LO are detected at time t− ₁ immediately before the power source switching, and M1Now = time t _{+ 1} immediately after the power source switching. This is the case when LO is detected. In this case, −1 is corrected. Thereafter, +1 is counted when M1 changes from LO to HI (t _{+ 1} ′).

FIG. 7B is a time chart when switching from the battery power source to the main power source. M1Last = LO and M0Last = LO are detected at time t− ₁ immediately before the power source switching, and at time t _{+ 1} immediately after the power source switching. This is a case where M1Now = HI is detected. In this case, +1 is corrected.

  Note that the cycle of intermittent driving and the power supply time during battery power supply are related to the rotation speed at which multiple rotation amounts can be detected. The number of samples for one rotation is determined by the period. In order to recognize 4 patterns in which the relationship (M1, M0) of the multi-rotation signals M1, M0 is (HI, LO), (HI, HI), (LO, HI), (LO, LO) Set a period that allows at least 4 samplings. Further, since the ratio between the HI and LO sections of M1 and M0 is determined by the power supply time, the relationship (M1, M0) of the multi-rotation signals M1 and M0 is (HI, LO), (HI, HI), (LO, HI). ), (LO, LO) The power supply time for recognizing the four patterns is set. The intermittent drive cycle and the power supply time are set as parameters.

  Further, if the rotation speed is simply calculated from the period of the multi-rotation signal using a timer and the intermittent drive period is switched in proportion to the rotation speed, the power consumption can be further reduced. Further, by making the power supply time variable and switching the power supply time to an optimum value according to the comparator output characteristics of the multi-rotation signal, it is possible to further reduce power consumption.

  As described above, in this embodiment, power is supplied to the multi-rotation detection sensor unit by intermittent drive when battery power is supplied, so that power consumption can be further reduced. Also, when switching between the main power supply and battery power supply, the multi-rotation signal immediately before and immediately after the switching is detected, and the multi-rotation amount is corrected from the state of the multi-rotation signal immediately before and immediately after the switching, so intermittent drive at the time of battery power supply Even if there is a difference in the multi-rotation signal from when the main power is supplied, the count error of the multi-rotation amount can be eliminated as long as it is within the specified error, and the absolute value is accurate even when the power is switched during motor rotation Position data can be detected.

  The present invention can be applied to an absolute value encoder that detects the rotational position of a servo motor used in a robot, an NC machine tool, or the like.

Claims (5)

A multi-rotation detection sensor unit that includes at least two magnetic field detection elements and detects the multi-rotation amount of the rotating body;
A drive unit for driving the magnetic field detection element;
A position sensor for detecting position within one rotation for detecting a position within one rotation of the rotating body;
A multi-rotation amount calculation unit that converts a two-phase multi-rotation detection signal output from the multi-rotation detection sensor unit into a rectangular wave through a comparator, and calculates a multi-rotation amount from the multi-rotation signal converted into the rectangular wave; ,
A one-revolution position calculation unit that takes in the one-revolution position detection signal output from the one-revolution position detection sensor through an AD converter and calculates an absolute position within one rotation;
A power source switching unit that switches between the main power source and the battery power source and supplies the battery power source when the main power source is shut off;
An absolute position generation unit that combines the absolute position within one rotation and the amount of multiple rotations to generate an absolute position ;
With
The multi-rotation amount calculation unit
A first multi-rotation amount calculator that calculates the multi-rotation amount when the main power is supplied;
A second multi-rotation amount calculating unit that calculates the multi-rotation amount when supplying battery power;
A multi-rotation amount correction unit that acquires the state of the multi-rotation signal immediately before power switching and immediately after power switching and corrects the initial value of the multi-rotation amount after power switching when switching between the main power supply and the battery power supply and,
An absolute encoder device comprising: The absolute value encoder device according to claim 1 , wherein the driving unit supplies pulsed power having a constant cycle to the magnetic field detection element when battery power is supplied. The absolute value encoder apparatus according to claim 2 , wherein the pulse period of the pulsed power source is switched according to a rotation speed of the rotating body. 4. The absolute value encoder device according to claim 2 , wherein a pulse width of the pulsed power supply can be set according to rising and falling characteristics of the multi-rotation signal when battery power is supplied. A multi-rotation detection sensor unit that includes at least two magnetic field detection elements and detects the multi-rotation amount of the rotating body;
A drive unit for driving the magnetic field detection element;
A position sensor for detecting position within one rotation for detecting a position within one rotation of the rotating body;
A multi-rotation amount calculation unit that converts a two-phase multi-rotation detection signal output from the multi-rotation detection sensor unit into a rectangular wave through a comparator, and calculates a multi-rotation amount from the multi-rotation signal converted into the rectangular wave; ,
A one-revolution position calculation unit that takes in a one-revolution position detection signal output from the one-revolution position detection sensor through an AD converter, and calculates an absolute position within one rotation;
A power source switching unit that switches between the main power source and the battery power source and supplies the battery power source when the main power source is shut off;
An absolute position generation unit that combines the absolute position within one rotation and the amount of multiple rotations to generate an absolute position ;
With
The multi-rotation amount calculation unit
A first multi-rotation amount calculator that calculates the multi-rotation amount when the main power is supplied;
A second multi-rotation amount calculating unit that calculates the multi-rotation amount when supplying battery power ;
Using an absolute encoder device with
The first multi-rotation amount calculation unit calculates the multi-rotation amount at the time of main power supply,
The second multi-rotation amount calculation unit calculates the multi-rotation amount at the time of battery power supply,
Acquire the state of the multi-rotation signal immediately before power switching and immediately after power switching at the time of switching between main power supply and battery power supply,
A multi-rotation detection method for an absolute value encoder device , which corrects an initial value of a multi-rotation amount after power switching.

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