JPS6056074B2 - Reference position detection method for pulse motor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a reference position detection method for a pulse motor.

Conventionally, when using a pulse motor, the zero point is determined in advance by forcibly reversing the motor to an external stopper position when the power is turned on, or by detecting a reference position using a reed switch instead of a stopper. Thereafter, the angle of each rotation step of the pulse motor is memorized by a counter or the like to obtain the current rotational position.

That is, the rotational position once determined from the reference position when the power is turned on is only detected by the value of the counter counted when the pulse motor is operated.

Therefore, even if there is a difference between the rotational position of the pulse motor and the counter value due to vibration or external force, it is difficult to correct it.
This has the problem that the correct rotational position may not be known in some cases. In addition, when detecting the reference position using a stopper or reed switch, under the worst conditions, approximately 3
There was also the problem that it was necessary to rotate the device by 60 degrees to detect the reference position, resulting in unnecessary operations. The main object of the present invention is to take into account the problems of the conventional method described above, and to provide a disk with a plurality of marks of different lengths on the rotating shaft of a pulse motor, and to measure the length of the marks with a sensor. The idea is to ensure that the detected rotational position always correctly indicates the actual rotational position of the pulse motor even when subjected to vibrations or external forces.

In the present invention, a plurality of marks of different lengths are provided on a disc attached to the rotating shaft of a pulse motor, and a sensor provided near the disc detects the marks.
A method for detecting a reference position of a pulse motor is provided, which measures the length of the mark and thereby detects the reference position of the pulse motor.

An apparatus using a method for detecting a reference position of an electric motor as an embodiment of the present invention is shown in FIGS. 1 to 4. FIG. 1 is a plan view showing the configuration of the pulse motor section of this device.
FIG. 2 is a side view of the apparatus of FIG.

The pulse motor 1 is of a conventional type and has gears 2 and 3.
It has a structure in which the central shaft 6 rotates through. Gears 2 and 3 are selected so that the central shaft 6 rotates once for every 96 pulses applied to the pulse motor. That is, one step rotates 3.75 degrees. The central shaft 6 is provided with a disk 4 having slits at four locations for detecting the rotational position, and pulse motor rotational position detection sensors 5 consisting of light emitting diodes and phototransistors sandwich the disk 4 above and below. It is arranged as follows. FIG. 3 is a plan view showing details of the disc 4. As shown in FIG.

Arc-shaped slits 41, 42, 43 and 44 having mutually different lengths are cut out in the disc 4 from reference positions every 90 degrees. The lengths of the slits correspond to the angles at which each arcuate slit is viewed from the center of the disk 4, and the slit 41 is 15 degrees, the slit 42 is 30 degrees, the slit 43 is 45 degrees, and the slit 44 is 60 degrees. Yes, if you match the number of steps of the pulse motor, the slit 41 has 4 steps, the slit 42 has 8 steps, and the slit 43 has 12 steps.
The number of steps and slits 44 is 16. FIG. 4 is a circuit diagram for connecting the above-mentioned pulse motor section to a microcomputer and operating it.

The rotational position counter 7 in the figure will be described later. The rotor 17 of the pulse motor 1 operates in a stepwise manner by applying output signals from the input/output ports φ1, φ2, φ3, φ of the microcomputer 10 to the coils 15 and 16.

For example, if φ1, φ2, φ3 and φ4 are respectively 1, 1, 0 and O in binary numbers, transistors 11 and 1
3 is on, transistors 12 and 14 are off, and the magnetic field in the coil 15 is 270 degrees (the horizontal right direction is 0 degrees). Therefore, in FIG.
The coil 16 has a magnetic field directed 180 degrees to the left in the direction of the coil 16 in the figure. is generated, and the resultant force is in the 225 degree direction. From the above state, φ1, φ2, φ3 and φ4
When the output signals of are changed to 011, 1 and O, respectively, transistors 12 and 13 are on,
1 and 14 are turned off, a magnetic field in the 90 degree direction is generated in the coil 15, a magnetic field in the 180 degree direction is generated in the coil 16,
The resultant force becomes 135 degrees, and the pulse motor rotates 90 degrees to the right. By sequentially outputting φ1, φ2, φ3, and φ4 as 010, 1, and 1, then 1, 0, 0, and 1, it rotates clockwise in steps of 90 degrees. A time course diagram of the output signals of φ1, φ2, φ3 and φ4 is shown in FIG. In the figure, the horizontal axis indicates time, and the vertical axis indicates the "0" level or "1" level. To rotate counterclockwise, change φ1, φ2, φ3, φ4 to “1, 1, 0,
0 above "1, 0, 0, 1", "0, 0, 1, 1", "0,
This is achieved by outputting "1, 1, 0". Figure 6 shows φ1 and φ when rotating around 7 to the left, similar to Figure 5.
A time course diagram of the output signals of 2, φ3, and φ4 is shown. The rotor 17 of the pulse motor 1 is decelerated via the gears 2 and 3, rotating the disk 4 by 3.75 degrees.

If the disk 4 is provided with a slit, the light from the light emitting diode 20 passes through the slit to the phototransistor 2.
The phototransistor 21 is turned on and outputs the "0" level to Spms. Also, shaved
When there is no light emitting diode 20, the light from the light emitting diode 20 is not transmitted and the phototransistor 21 is turned off, setting the level "1" to Spms.
Output to. Therefore, when there is no slit, Spms is
1", and "0" if there is a slit. When rotated 360 degrees (96 steps) clockwise, Spm
A waveform diagram of the s signal over time is shown in FIG. The shaded area in the figure is the period where the slit is present. A method of detecting the reference position of the rotor of a pulse motor when the power is turned on using the signal shown in FIG. 7 will be explained with reference to the flowchart shown in FIG.

The flags of FPCND1 and FPCND2 are reset when the power is first turned on.

When PCNDl under the flag is 0 in step 100, that is, when the reference position has not been detected yet, the process proceeds to step 101. When the flag FPCND2=0 indicating the time to start counting in step 101, the process proceeds to step 102 and it is determined whether or not there is a slit. If there is no slit, proceed to step 103; if there is a slit, proceed to step 105. In step 103, FPCND2=1
, and proceed to step 104. In step 104, a counter CPCND for counting the number of slit steps is cleared to prepare for counting the number of slit steps. If there is a slit when the power is turned on, step 10
Step 10 from 2 to 105 until there are no more slits
3 and 104 are skipped. In step 105, the pulse motor is rotated one step clockwise. Step 10
1 and FPCND2=1, the process advances to step 106 and it is determined whether or not there is a slit. If there are slits, step 1 to count the number of steps with slits.
07, CPCND+1→CPCND is executed and counted up. Then, the process returns to step 105, and the rotation is made to the right again by one step. If there are no slits in step 106, it is assumed that the number of steps with slits has been found, except when CPCND=0, and the process proceeds to step 108, where the contents of the counter CPCND are determined. When CPCND=O, return to step 105 and rotate clockwise by one step. C
The actual slit step number is stored in PCND, and the rotational position counter 7 (FIG. 4) is set according to the value of CPCND by classifying as follows, allowing a reading error of ±1. That is, when CPCND=3, 4, or 5, the rotational position counter 7 is set to 0 in step 109, and when CPCND=7, 8, or 9, the rotational position counter 7 is set to 0.
10, set the rotational position counter 7 to 24, and set the CPCN
When D=11, 12 or 13, step 111 sets the rotational position counter 7 to 48, and CPCND=15.
, 16 or 17, the rotational position counter 7 is set to 72 in step 112. If the value of CPCND is other than the above-mentioned value, it is assumed that the reading of the slit step number has failed, the flag of FPCND2 is reset, and the operation according to the flowchart of FIG. 8 is repeated. When the rotational position counter 7 is set, the detection of the reference position at the time of power-on is completed, the flag of FPCNDl is set to 1, and the position detection routine is completed. The above explanation has been made regarding the detection of the reference position of the pulse motor when the power is turned on according to the flowchart of FIG. 8, but the explanation will be further supplemented using FIG. 9.

First, the photo sensor that determines the presence or absence of a slit is placed at point A, and when the power is turned on, it is placed at the position shown in FIG. 9a.
Assuming that the disc provided with the slit engaged with the rotating shaft of the pulse motor is stationary, the steps of performing the detection method according to the flowchart of FIG. 8 described above are as follows. Since there is no slit at the current position, rotate it clockwise until there is a slit so that point B is on the AO line.

The 0 point is the center point of the disk.

Rotate the disk clockwise from the position of point B, and during the slit period,
CPCN is the number of steps of the pulse motor that rotates the disk.
Count with D. When counting reaches point C, it is determined that there is no slit, and counting ends. The reference position is detected based on the count value of CPCND at that time. In this example CPCND=12
Therefore, the rotational position (point C) is 48, that is, 18 in Figure 7.
It can be seen that it is at the reference position of 0 degrees. The position of the pulse motor when the detection is completed is shown in FIG. 9b. The position of the pulse motor when the detection is completed in this example depends on the position of the disk before the position detection, and there are four positions: 0 degrees, 90 degrees, 180 degrees, and 270 degrees. In the above embodiment, the light emitting diodes and phototransistors were arranged vertically across a disk, and the rotational position of the rotor was detected by the presence or absence of slits. The light emitting diode and the phototransistor may be configured on the same surface by printing, and when there is no printing, the light from the light emitting diode is reflected by the disk to turn on the phototransistor.

Furthermore, although slits are provided at four locations in this embodiment, the number may be arbitrary. Furthermore, in this embodiment, the method of detecting the rotational position of the pulse motor when the power is turned on has been described as an example, but according to predetermined conditions, , it is possible to repeat the position detection routine described above, and the correct rotational position can be indicated to the rotational position counter.

According to the present invention, the detected value of the rotational position of the pulse motor can always be correctly indicated even when subjected to vibration or external force.

[Brief explanation of drawings]

1 is a plan view showing the configuration of a pulse motor section of an apparatus for performing a reference position detection method for a pulse motor as an embodiment of the present invention; FIG. 2 is a side view of the pulse motor section of FIG. 1; Fig. 3 is a plan view showing the structure of the disk provided in the pulse motor part of Fig. 1, Fig. 4 is a circuit diagram of the pulse motor part of Fig. 1, and Fig. 5 F is a plan view of the pulse motor part of Fig. 1. A waveform diagram of the pulses supplied when rotating the rotor clockwise,
Figure 6 is a waveform diagram of pulses supplied when rotating the rotor of a pulse motor in the counterclockwise direction similar to Figure 5, and Figure 7 is a rotational position detection provided in the pulse motor part of Figure 1. A waveform diagram showing the output of the sensor, FIG. 8 is a flowchart explaining a method for detecting a reference position of a pulse motor as an embodiment of the present invention, and FIG. 9 shows a method for detecting a reference position of a pulse motor as an embodiment of the present invention. FIG. 4 is a plan view showing the rotational position of the disk in FIG. 3 for explaining the method; 1... Pulse electric motor, 2, 3... Gear, 4... Disk, 5... Rotational position detection sensor, 6... Central axis, 7... Rotation position counter, 10... Microcomputer, 1
1, 12, 13, 14...transistor, 15
, 16... Coil, 17... Rotor,
20... Light emitting diode, 21... Phototransistor, 41, 42, 43, 44...
·slit.

Claims (1)

[Claims] 1. A plurality of marks of different lengths are provided on a disc attached to the rotating shaft of a pulse motor, and the marks are detected by a sensor provided near the disc, and the marks are A method for detecting the reference position of a pulse motor by measuring the length of the motor and detecting the reference position of the pulse motor. 2. The reference position detection method for a pulse motor according to claim 1, wherein a light emitting member and a phototransistor are used as the sensor, and a slit provided in the disk is used as the mark. 3 The difference in the length of the mark is the same as that of the pulse motor.
The reference position detection method for a pulse motor according to claim 1, wherein the step length is four times or more longer than the step length.