JPS6349119Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a stepping motor drive circuit that sequentially sets each mode of high speed mode, low speed mode, and hold mode, and forms a drive signal for rotating the stepping motor by a predetermined angle. Regarding.

2. Description of the Related Art Conventionally, a stepping motor is used as a drive device for quickly moving a moving body from a current position to a predetermined position and setting it at a predetermined position with high precision. In order to move the moving object in this way, the rotation angle of the stepping motor must be regulated with high precision. For this purpose, a sensor is provided to detect the rotation angle of the stepping motor.
The output signal of the sensor forms a drive signal for the stepping motor to set the stepping motor in high speed mode, low speed mode, or hold mode, and stops the stepping motor when it has rotated by a predetermined angle. Therefore, in order to quickly and accurately set a moving object in a predetermined position,
It is necessary to form drive signals for each mode with high precision.

An example of a device that uses such a stepping motor as a driving device is a printer. Below, we will take a type wheel of a printer as an example of a moving object.
A conventional drive circuit for forming a drive signal for a stepping motor that rotationally drives the type wheel will be described.

FIG. 1 is a schematic perspective view showing an example of a conventional type wheel drive mechanism, in which 1 is a type wheel;
2 and 3 are gears, 4 is a dividing plate, 5 is a sensor, and 6 is a stepping motor.

In the figure, when the stepping motor 6 rotates, this rotation is transmitted to the type wheel 1 via the gears 3 and 2. A large number of type arms having type characters are attached to the type wheel 1 in a petal shape, and the desired type type is moved from the current position to a predetermined position where it can be printed, that is, a printing position.
The stepping motor 6 rotates.

Further, a dividing plate 4 having a large number of notches is attached to the rotating shaft of the stepping motor 6, and a sensor 5 is provided opposite to this dividing plate 4. The sensor 5 is, for example, a photo sensor, and when the stepping motor 6 rotates, a pulse signal representing the rotational phase of the stepping motor 6 is obtained from the sensor 5 due to the cut in the dividing plate 4. Therefore, the rotation angle of the stepping motor can be known from this pulse signal, and thereby each mode of the stepping motor 6 can be set.

FIG. 2 is a block diagram showing a row of conventional drive circuits that use such pulse signals to form drive signals for each mode of the stepping motor 6, in which 7 is a drive circuit, 8 is a pulse count unit, and 9 is a drive circuit. Hold pulse pattern generator, 1
0 is a comparison unit, 11 is a pulse converter, and 12 is a drive amplifier, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In FIG. 2, a pulse signal from a sensor 5 is supplied to a pulse count unit 8 of a drive circuit 7 and a hold pulse pattern generation circuit 9.
The pulse count unit 8 counts the pulse signals and sequentially supplies the count value to the comparison unit 10.

The comparison unit 10 includes a stepping motor 6.
Numerical values corresponding to the rotation angle for each mode are set as reference values, and the comparison unit 10 compares these reference values with the count value from the pulse count unit 8 and generates a command signal for each mode. These reference values, which are set in the comparison unit 10 and represent the switching points of each mode, vary depending on the number of steps required for the type to move to the printing position (hereinafter referred to as the number of moving steps), and all of these values are memorized. When the number of moving steps is specified, the numerical values corresponding to the specified number of moving steps are read from the memory, and these numerical values are compared with the count value from the pulse count unit 8. Each mode is set for the specified number of movement steps.

On the other hand, the hold pulse pattern generator 9 is phase-synchronized with the pulse signal supplied from the sensor 5,
The stepping motor 6 generates a signal corresponding to a drive signal in the hold mode, that is, a hold pulse pattern. This hold pulse pattern is supplied to the pulse converter 11, converted based on the command signal from the comparison unit 10, amplified by the drive amplifier 12 as a drive signal, and supplied to the stepping motor 6.

FIG. 3 is a speed curve diagram showing an example of a method of driving the stepping motor 6. As shown in FIG. In this figure, the current position of the desired type to be printed on the type wheel 1 (FIG. 1) is set at an angle O as the reference position, and the angle D is set as the printing position.

For this type, stepping motor 6
is accelerated in high speed mode H _i from angle O to angle A, decelerated in hold mode H _p from angle A to angle B, and from angle B to angle C.
From angle C to angle D, set to low speed mode L _p , and then from angle C to angle D, set hold mode H _p to decelerate.
It is made to stop when the desired type has rotated by an angle D.

This angle is also expressed by the count value of the pulse count unit 8, and the angles A, B, C
is also expressed by the reference value set in the comparison unit 10. By comparing these angles in the comparison unit 10, each mode of the stepping motor 6 can be commanded.

Note that FIG. 3 shows an example of a method of driving the stepping motor 6, but the order of the modes is generally set as shown above, and the order of the modes varies depending on the angle from the current position to the printing position. mode,
The length of low speed mode and hold mode is set,
Therefore, the reference value set in the comparison unit 10 differs depending on the required rotation angle of the stepping motor 6. However, the hold mode is always set at the end, and in this hold mode, each reference value is set so that the stepping motor 6 is decelerated and the desired type is stopped at the printing position.

FIG. 4 is a curve diagram showing the torque of the stepping motor 6 in each mode, where a is a torque curve in the hold mode, b is a torque curve in a low speed mode, and c is a torque curve in a high speed mode. This is the torque curve of Further, the angle O is the current position of the type, and when the torque is positive, the stepping motor 6 attempts to rotate in the direction of the arrow X. When the torque is negative, it tries to rotate in the direction of arrow Y in the opposite direction.

Therefore, when the stepping motor 6 is in the hold mode, the torque is zero at the current position, and when the stepping motor 6 deviates from this position, a torque in the opposite direction is generated to return it to the current position. Therefore, in FIG. 3, high speed mode H _i or low speed mode L _p
When switching from to hold mode _Hp , a torque is generated in the stepping motor 6 at each moment to maintain the state at that moment, and as a result, the stepping motor 6 is braked and decelerated.

In the low speed mode, as shown in FIG. 4b, the torque curve is set so that it is maximum at the current position and decreases as the engine rotates. Therefore, if the torque curve is set as shown in FIG. 4b, the maximum torque will be generated as the motor rotates in the direction of the arrow X, and the torque will decrease as the motor rotates.

In the high-speed mode, a torque curve is set that is zero at the current position and increases as the motor rotates. In this case, in FIG. 3, the angle O
When the high-speed mode H _i is set, the torque at this time is zero, so the stepping motor 6
cannot rotate, and if a rotational force is applied in the opposite direction to the desired direction for some reason, it will begin to rotate in that direction, making it extremely unstable. For this purpose, in practice, the low speed mode is once set and the high speed mode H _i is set after rotating in the desired direction.

The reason why the torque in high-speed mode is set in this way is that there is a delay in the rise of the supplied current due to the inductance component of the coil of the stepping motor 6.
For this reason, the force generated by the supply current generated in the stepping motor 6 is delayed, so the maximum torque point of the stepping motor 6 is shifted in consideration of this delay, and the maximum torque point of the stepping motor 6 is shifted. It improves efficiency by producing maximum power when

As described above, in order to form a drive signal for the stepping motor 6 in each mode, the hold pulse pattern generator 9 and the pulse converter 11
is provided.

The hold pulse pattern generator 9 generates a signal having the same phase as the drive signal of the stepping motor 6 in the hold mode, that is, a hold pulse pattern in synchronization with the pulse signal from the sensor 5. The pulse converter 11 is connected to the comparison unit 1
A drive signal is formed by shifting the phase of the hold pulse pattern according to each mode according to a command signal from 0. In the high speed mode, the hold pulse pattern is phase shifted by a predetermined amount, and in the low speed mode, the hold pulse pattern is shifted. The phase is shifted by another predetermined amount, and in the hold mode, the phase of the hold pulse pattern is kept unchanged.

FIG. 5 is a timing chart illustrating an example of the operation of the drive circuit 7 when the stepping motor 6 is 4-phase excited, where S is the output pulse signal of the sensor 5, H _A , H _B , H _C , H _D is the output signal (hold pulse pattern) of the hold pulse pattern generator 9, and C _A , C _B , C _C , and C _D are drive signals from the pulse converter 11, which are applied to each phase coil of the stepping motor 6. It is supplied.

Now, the rotation of the stepping motor 6 required for the sensor 5 to output one cycle of the pulse signal is 1 rotation.
A case will be described in which the stepping motor 6 rotates 19 steps in order to move the desired type on the type wheel 1 from the current position to the printing position. When starting the ping motor 6,
First, a one-step low-speed mode L _p is set, and when the stepping motor 6 starts rotating, a high-speed mode H _i , a hold mode H _p , and a low-speed mode L _p are sequentially set, and finally, the hold mode H _p is set. The stepping mode 6 shall be controlled so that the above-mentioned type is set at the printing position, and the first switching from the low speed mode L _p to the high speed mode H _i is in the first step, and the high speed mode H _i Switching from the hold mode H _p to the hold mode H p is the 8th step, and switching from the hold mode H _p to the low speed mode L _p is the 12th step.
At the 17th step, switching from this low speed mode L _p to the hold mode H _p is performed at the 17th step, and when the switch is made at such a step,
It is assumed that the desired type is set at the print position.

Now, the hold pulse pattern generator 9 shown in FIG. 2 generates four signals H _A , H _B , H _C , _HD which are phase synchronized with the pulse signal S from the sensor 5 . These signals have a period equal to four periods of the pulse signal S, that is, four steps, and alternately have rising and falling every two steps. The phases of these signals are sequentially different by π/2 radians, and the phases of the signals H _A , _HB , _HC , and _HD are advanced by π/2 radians in that order.

Now, let us assume that the high level of these signals is "1" and the low level is "0", and the signals H _A , H _B ,
Combination of levels of H _C and _HD (H _A , H _B , H _C ,
H _D ), (1, 1, 0, 0), (1, 0,
0,1), (0,0,1,1), (0,1,1,0)
The combination of levels changes step by step in this order, and is repeated every four steps. When a change pattern of such level combinations (partial patterns), that is, a pulse pattern, is generated from the hold pulse pattern generator 9, and the drive signal has such a pulse pattern, the stepping motor 6 is set to the hold mode. This pulse pattern is a hold pulse pattern.

The pulse converter 11 receives the signals H _A , H _B , H _C ,
_HD is phase shifted in high speed mode and low speed mode. The amount of phase shift in high speed mode is π radians (2 steps), and the amount of phase shift in low speed mode is 3π/
2 radians (3 steps). This means that
In high-speed mode, this is nothing more than converting the partial pattern of the hold pulse pattern as follows. That is, (1,1,0,0)→(0,0,1,1) (1,0,0,1)→(0,1,1,0) (0,0,1,1)→ (1,1,0,0) (0,1,1,0)→(1,0,0,1) Therefore, in the hold mode, the voltage is supplied to the first phase coil of the stepping motor 6. signal,
(i.e., coil signal) C _A is signal H _A , second phase coil signal C _B is signal H _B , third phase coil signal C _C
is the signal H _C and the fourth phase coil signal C _D is the signal H _D. In high-speed mode, the coil signal C _A is the signal H C.
H _C to coil signal C _B to signal H _D , coil signal C _C
It is sufficient to use the signal H _A as the coil signal C _D and the signal H _B as the coil signal C D. This results in the torque curve of FIG. 4c, which is the torque curve of FIG. 4a shifted to the right by π radians.

Similarly, in the low speed mode, the partial pattern of the hold pulse pattern is converted as follows. That is, (1,1,0,0)→(1,0,0,1) (1,0,0,1)→(0,0,1,1) (0,0,1,1)→ (0,1,1,0) (0,1,1,0)→(1,1,0,0) Therefore, in this case, the coil signal C _A becomes the signal H _B , and the coil signal C _B to signal H _C , coil signal C _C to signal H _D , and coil signal C _D to signal H _A
And it is sufficient. This results in the torque curve shown in FIG. 4b being shifted from the torque curve shown in FIG. 4a to the right by π/2 radians.

The pulse count unit 8 is a subtraction circuit that subtracts 1 for each pulse of the pulse signal from the sensor 5, and is initially set to a value of 19.

Therefore, when the stepping motor 6 is started, the value 19 from the pulse count unit 8 is supplied to the comparator unit 10, and a command signal for the low speed mode _Lp is supplied to the pulse converter 11. Based on this command signal, the pulse converter 11 converts the supplied hold pulse pattern as described above, and generates a drive signal corresponding to the low speed mode L _p . This drive signal is amplified by a drive amplifier 12 and supplied to the stepping motor 6 as a coil signal.

Therefore, the stepping motor 6 rotates at a low speed,
A pulse signal is obtained from the sensor 5. When the pulse count unit 8 reaches a count value of 18 (first step), the comparison unit 10 detects this and gives a command signal for the high speed mode _Hi to the pulse converter 11. The pulse converter 11 converts the hold pulse pattern as described above based on this command signal, and the stepping motor 6 switches to the high speed mode H _i
It rotates at an accelerated pace.

Next, when the count value of pulse count unit 8 reaches 11 at the 8th step, comparison unit 1
0 issues a command signal for the hold mode _Hp , and the pulse converter 11 generates a drive signal with the same pulse pattern as the hold pulse pattern. For this purpose, the stepping motor 6 is in the hold mode.
H _p , and the brake is applied to decelerate the rotation.

Furthermore, when the count value of pulse count unit 8 reaches 7 at the 12th step, comparison unit 1
0 issues a command signal for the low speed mode _Lp , the pulse converter 11 converts the hold pulse pattern as described above, and the stepping motor 6 rotates at a low speed.

Then, when the count value of the pulse count unit becomes 2 at the 17th step, the comparison unit 10
A command signal for hold mode H _p is generated from
The stepping motor 6 decelerates and stops when the desired character comes to the printing position.

In this way, the stepping motor 6 is controlled and the desired type is set at the printing position, but in order to set the position accurately,
The rotation speed of the stepping motor 6 in each mode must be accurate. For example, if it is assumed that the type at the current position (angle O) is accurately set to the printing position at angle D by passing through a speed curve as shown in FIG _.
Even if at least one of the speeds changes slightly in the low speed mode L _p , the type will not stop at angle D, and even if the brake action in the hold mode H _p is slightly out of order, the type will deviate from the printing position. and stop.

As described above, in the method of controlling a stepping motor using this conventional drive circuit, the accuracy of the rotational speed of the stepping motor in each mode is a very important point.

However, in order to be able to control such a stepping motor, the stepping motor must be designed so that the desired speed characteristics can be obtained with high accuracy, and the stepping motor must be designed so that the desired speed characteristics can be obtained with high accuracy. The mode switching point (number of steps) is set according to the speed characteristics of the stepping motor, but the design value and the actual value do not necessarily match, and some errors inevitably occur, resulting in The accuracy of position setting will be low. In order to solve such problems,
It is sufficient to measure the characteristics of the stepping motor in advance and set the mode switching point for each number of moving steps based on the measurement results. Create and use a memory that stores reference values according to characteristics, and use these reference values in comparison unit 1.
0 (FIG. 2), which is unrealistic.

In addition, all values that may be used as the above reference values are predicted from the expected characteristic error range of the stepping motor, and these values are stored in the above memory. It is conceivable to use only the necessary reference values based on the measurement results, but this has the disadvantage that the memory capacity becomes very large.

Furthermore, even if the speed characteristics and mode switching points of a stepping motor can be set with high precision during manufacturing, the speed characteristics of a stepping motor will depend on the surrounding environment such as temperature and humidity. Since it changes over time and is accompanied by aging, the accuracy of setting the position of printed characters deteriorates. This problem cannot be avoided once the above-mentioned memory is installed.

The above applies not only to setting the position of type in a printer, but also to devices that use stepping motors to move moving objects in general. It was practically impossible to do well.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art,
It is possible to set the mode switching point of the stepping motor according to the characteristics of the stepping motor, thereby increasing the accuracy of positioning of a moving object and reducing the number of data that defines the operation of the stepping motor. An object of the present invention is to provide a stepping motor drive circuit that can reduce memory capacity.

In order to achieve this objective, the present invention uses predetermined data to perform a predetermined operation on a stepping motor. The data can be corrected based on the difference between the stepping motor and the stepping motor, and the number of movement steps corresponding to all predetermined operations of the stepping motor is divided into a plurality of blocks, and the magnification corresponding to each block is stored in a memory. , the data is formed by calculating the number of moving steps designated to cause the stepping motor to perform a predetermined operation and the magnification of the block to which the number of steps belongs; The present invention is characterized in that a corrected magnification is obtained by calculating the number of movement steps, and the magnification is stored in the memory as a new magnification so that it can be used as a magnification for forming the next data. .

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 is a block diagram showing an embodiment of the stepping motor drive circuit according to the present invention, in which 13 is a fall detector, 14 is a pulse interval detector, 15 is a time/speed converter, and 16 is an AND gate, 17 is an OR circuit, 18, 19, 20, 21 are registers, 22, 23, 24 are comparators, 25, 2
6, 27 are arithmetic units, 28, 29, 30 are registers, 31 are comparators, 32 are registers, 33, 3
4, 35, 36 are comparators, 37, 38 are programmable delay circuits, 39, 40 are AND gates, 4
1 is an OR circuit, 42, 43, 44 are inverters,
45 is a data forming unit, 46 is a control unit, and 47 is an amplifier, and parts corresponding to those in FIG. 2 are given the same reference numerals, and a description thereof will be partially omitted.

In FIG. 6, the pulse signal S from the sensor 5
is amplified by an amplifier 47 and supplied to the fall detector 13 of the drive circuit 7 according to the present invention. The falling edge detector 13 generates a pulse signal that coincides with the falling edge of the supplied pulse signal S, that is, a falling pulse signal a, and this falling pulse signal a is sent to the pulse interval detector 14 and the pulse count unit. 8 and AND gate 16.

When the output level of the comparator 33 is low level (hereinafter referred to as
(referred to as "L"), the AND gate 16 is in a conductive state by the inverter 44, and the falling pulse signal a is transmitted to the AND gate 16 and the OR circuit 17.
The signal is supplied to the hold pulse pattern generator 9 via the hold pulse pattern generator 9. For this purpose, the hold pulse pattern generator 9 generates a hold pulse pattern H that is phase synchronized with the falling pulse signal a, and therefore the pulse signal S from the sensor 5, and the pulse converter 11 converts this hold pulse pattern into A drive signal C is generated by performing processing according to each mode. The stepping motor 6 is controlled by the drive signal C, and the above operation is similar to the conventional drive circuit shown in FIG.

The pulse interval detector 14 measures the time interval between each pulse of the falling pulse signal a, and the time/speed converter 15 calculates each step of the stepping motor 6 from the time interval detected by the pulse interval detector 14. Detect the average rotational speed for each rotation. Therefore, the pulse interval detector 14 and the time/speed converter 15 constitute a speed detection unit.

Comparators 33, 34, 35, 36 correspond to comparison unit 10 of FIG. The comparator 34 compares the count value M of the pulse count unit 8 with the register 2.
Compare the value N ₁ stored in 9 and find that M>N ₁
At this time, a high-speed command signal h _i of high level (hereinafter referred to as "H") is generated. The comparator 35 receives the count value M of the pulse count unit 8 and the register 2.
Numeric value N ₁ stored in 9 and register 30
A numerical value N ₂ stored in is supplied, and N ₁ ≧M>
When _N2 , a hold command signal _hp of "H" is generated. The comparator 36 is connected to the pulse counting unit 8
The count value M is compared with the numerical value N ₂ stored in the register 30, and when N ₂ ≧M, a low speed command signal l _p of “H” is generated. Furthermore, the comparator 33
is for setting the hold mode which is the final mode of the stepping motor 6, and a certain reference value is set, and when the count value M of the pulse count unit 8 becomes equal to this reference value. , generates an "H" output signal f, which becomes the hold command signal h _p .

The high speed command signal h _i from the comparator 34 is supplied to the pulse converter 11 through the AND gate 39, and puts the pulse converter 11 into the high speed mode. Comparator 35
The hold command signal h _p from the pulse converter 11 is supplied to the pulse converter 11 through the OR circuit, and the pulse converter 11 is placed in the hold mode. The low speed command signal l _p from the comparator 36 is supplied to the pulse converter 11 through the AND gate 40, puts the pulse converter 11 into the low speed mode, and is inverted by the inverter 43 to turn the AND gate 39 into a cutoff state. This is because the numerical values stored in the registers 29 and 30 are set as described later, so that the low speed mode is prioritized over the high speed mode. Further, the "H" output signal f of the comparator 33 causes the pulse converter 11 to enter the hold mode through the OR circuit 41, and is inverted by the inverter 42 to cut off the AND gate 40. This is because the hold mode set by the output signal f of the comparator 33 is given priority over the low speed mode based on the numerical values similarly stored in the registers 29 and 30.

Here, this embodiment will be explained assuming that the control of the type wheel 1 (FIG. 1) of a printer is controlled and the stepping motor 6 exhibits the speed curve shown in FIG. 3. However, this is applicable not only to type wheels but also to drive control of general moving bodies. Although not shown in FIG. 3, it goes without saying that a one-step low-speed mode L _p is provided as an initial mode before the high-speed mode H _i .

Therefore, the pulse count unit 8 calculates the angle D
The number of steps when the stepping motor 6 rotates by the amount shown in FIG. 3 is preset, and counts down by one for each pulse of the falling pulse signal a. The pulse count unit 8 is also provided with a flip-flop circuit, for example, and when one falling pulse is supplied, the pulse count unit 8 detects that it has counted down by one, and performs high-speed counting as described later. A command signal indicating the start of mode H _i is generated.

On the other hand, the register 29 stores a numerical value (hereinafter referred to as the value of angle A) equal to the count value of the pulse count unit 8 when the stepping motor 6 rotates through the angle A (FIG. 3). The register 30 contains a value larger than the number of steps preset in the pulse count unit 8 (hereinafter referred to as the initial step value) and a value when the stepping motor 6 is at an angle B.
(FIG. 3) A numerical value (hereinafter referred to as the value of angle B) equal to the count value of the pulse count unit when the rotation is performed is selectively stored. The exchange of these initial stage values and the value of angle B in the register 30 is performed based on the above-mentioned command signal generated from the pulse count unit 8, and this command signal indicates that the count value of the pulse count unit 8 is This occurs when a count value corresponding to the boundary between the low speed mode and the high speed mode, which is the first stage mode of No. 6, is reached.

The preset values of the pulse count unit 8 and the numerical values stored in the registers 29 and 30 are stored in the data forming unit 4 under the control of the control unit 46.
5 and is supplied to the pulse count unit 8 and registers 29 and 30, and when one operation of the stepping motor 6 is completed, the registers 29 and 3 are
The numerical value stored in 0 is returned to the data forming unit 45 again. Further, the above command signal generated by the pulse count unit 8 is transmitted to the control unit 4.
6 and the numerical value stored in the register 30 is changed from the initial stage value to the value of angle B.

A reference value is set in the comparator 33, which is equal to the count value of the pulse count unit 8 when the stepping motor 6 rotates by an angle C (FIG. 3). Here, the number of steps in the final hold mode H _p period shown in FIG. 3 is determined by one operation of the stepping motor 6, that is, setting the desired type on the type wheel 1 (FIG. 1) at the printing position. The number of steps required for the pulse count unit 8 is constant regardless of the number of movement steps.
By providing a countdown function, the reference value of the comparator 33 can be kept constant.

Note that the comparator 31 is set to a reference value of zero, and by comparing this reference value with the count value M of the pulse count unit 8, it detects that this count value M has become zero and issues a movement end signal. occurs.

Next, a means for correcting errors in type wheel drive control due to errors in the speed characteristics of the stepping motor 6 and errors in brake action will be explained.

The function of this correction means is to correct the switching point (angle A) between the high speed mode H _i and the next hold mode H _p when there is a speed error of the stepping motor 6 in the high speed mode H _i in FIG. , if there is an error in the deceleration effect in the hold mode H _p following the high speed mode H _i , the time point (angle B) at which the next low speed mode L _p is switched is corrected. The switching instants modified in this way are used as the respective switching instants for the next operation with the same number of travel steps. That is, this correction means has a learning function that determines the length of each mode for the next movement with the same number of movement steps from the movement currently being performed.

For this purpose, the angle A stored in the register 29
and the value of the angle B stored in the register 30 are not constant, but are modified in accordance with the rotational speed of the stepping motor 6 detected by the time/speed converter 15.

That is, if the stepping motor 6 is designed to rotate with the speed curve shown in _{FIG .} A numerical value representing the designed rotational speed V _A of the stepping motor 6 to be generated (hereinafter referred to as the reference speed value R _A ) is stored in the register 21, and the register 21 also stores the hold mode H _p and the next low speed mode L _p A numerical value (hereinafter referred to as a reference speed value R B ) representing the designed rotational speed V _B of the stepping motor 6 that should be generated at the time of switching to the reference speed value R _B is stored.

The reference speed value R _A of the register 20 and a numerical value representing the rotational speed of the stepping motor 6 from the time/speed converter 15 (hereinafter referred to as the actual speed value R) are supplied to the comparator 23 . Comparator 23 is comparator 35
operates for a short period of time near the rising edge of the output signal (hold command signal h _p ), R _A > R, R _A = R,
It is determined whether R _A <R. This determination result is supplied to the arithmetic unit 26, and its output value is supplied to the register 29 as +1 when R _A >R, 0 when R _A =R, and -1 when R _A <R. The register 29 adds this output value to the stored value of angle A and corrects it as a new value of angle A to be used next time. By adding this output value, the stepping motor 6
_If the rotational speed _of
It is advanced by one step so that the actual speed value R at the time of switching from the high speed mode H _i to the hold mode H _p becomes equal to the reference speed value R _A .

In addition, the reference speed value R _B of the register 21 and the time
The actual speed value R from the speed converter 15 is connected to the comparator 24.
supplied to The comparator 24 operates for a short period of time near the rising edge of the output signal of the comparator 36 (low-speed command signal l _p ), and determines whether R _B > R, R _B = R, or R _B < R. . This judgment result is
When R _B >R, -1 when R _B =R, and 0 when R _B <R, +1 is supplied to the register 30 as its output value. The register 30 adds this output value to the stored value of angle B and corrects it as a new value of angle B to be used next time. As a result, when the braking action of the stepping motor 6 is large in the hold mode H _p following the high speed mode H _i (that is, when the deceleration effect is large), the hold mode H _p is changed to the low speed mode.
The angle B (FIG. 3) for switching to L _p is advanced by one step; conversely, when the braking action is small, angle B is delayed by one step, switching from the hold mode H _p to the low speed mode L _p . The actual speed value R at the time of the change is made equal to the reference speed R _B.

Note that the calculation units 26 and 27 are connected to the registers 29 and 30.
The timing for supplying the above output values to the respective modes is after at least one step has elapsed since the comparators 35 and 36 commanded the respective modes. This is to prevent the comparators 34, 35, and 36 from making erroneous decisions even if the reference speed values R _A and R _B in the registers 29 and 30 are corrected, respectively.

As is clear from the above explanation, register 2
The reference speed values R _A and R _B stored at 0 and 21 are constant values that vary depending on the number of movement steps of the type wheel 1 (FIG. 1) and are formed by the data forming unit 45; Once the number of movement steps is determined, the reference speed value corresponding to this number of movement steps is determined.
R _A and R _B are formed by the data forming unit 45 and stored in the registers 20 and 21.

As described above, the influence of the speed error of the stepping motor 6 and the brake action error can be prevented, and the printing position of the _type can be set well. By performing homing control, the positioning accuracy of printed characters is further improved. This is to control the braking action during this hold period according to the rotational speed of the stepping motor 6, and to perform final position adjustment of the printed characters.

Therefore, as mentioned above, when the count value M of the pulse count unit 8 reaches 2, the comparator 33 generates the output signal f of "H", thereby setting the hold mode H _p (hereinafter, this hold mode Mode H _p
A homing period F) is set; at the same time, this output signal f is inverted by the inverter 44 to turn off the AND gate 16.
At the same time, the output signal f is supplied to the programmable delay circuit 37, and as shown in FIG.
A delayed signal d ₁ delayed by T ₁ is obtained. This delay signal _d1 is supplied to the OR circuit 17 and the programmable delay circuit 38, and from the programmable delay circuit 38, as shown in FIG.
A delayed signal d ₂ delayed by T ₂ is obtained and supplied to the OR circuit 17 . Therefore, during the homing period F, the hold pulse generator 9 is phase synchronized with the rising edges of the delayed signals d ₁ and d ₂ supplied via the OR circuit 17, and generates the signals H _A , d with the phases shown in FIG.
A hold pulse pattern is obtained by H _B , H _C , _{and HD} , and drive signals C _A , C _B , C _C , and _CD of this hold pulse pattern are obtained from the pulse converter 11 .

The delay amount of the programmable delay circuit 37 is set by the numerical value (hereinafter referred to as delay amount) _D1 stored in the register 28, and the delay amount of the programmable delay circuit 38 is set by the numerical value (hereinafter referred to as delay amount) stored in the register 18. (hereinafter referred to as the delay value) is set by _D2 . The delay value D ₂ is a constant value that varies depending on the number of movement steps of the type on the type wheel 1 (Fig. 1), whereas the delay value D ₁ is the value when the count value M of the pulse count unit 8 is zero. It is adjusted according to the rotational speed of the stepping motor 6.

That is, the register 19 stores a numerical value (hereinafter referred to as reference speed value R _p ) representing the designed rotational speed V _p of the stepping motor 6 when the count value M of the pulse count unit 8 is zero. When the comparator 31 detects that the count value M has become zero, the reference speed value R _p and the actual speed value R are supplied to the comparator 22 . The comparator 22 is
When the comparator 31 detects that the count value M of the pulse count unit 8 has become zero, it operates for a short period of time and determines whether R _p > R, R _p = R, or R _p < R. . This judgment result is calculated by the computing unit 25.
When R _p >R, -1 when R _p =R, 0 when R _p <R, +1 is supplied to the register 28 as the output value. The register 28 adds this output value to the stored delay value D ₁ and corrects it as a new delay value D ₁ to be used next time. As a result, when the braking action is strong, the actual speed value R when the count value M is zero becomes small, and the desired type stops before the printing position, so the programmable delay circuit 37 The delay amount is shortened to weaken the brake action. Conversely, if the braking action is weak, the actual speed value R when the count value M is zero will increase, and the desired printed character will stop after passing the printing position, so the delay of the programmable delay circuit 37 will increase. Increase the amount so that the brake action becomes stronger.

The reference speed value R _p stored in the register 19 is
When the actual speed value R from the time/speed converter 15 when the count value M of the pulse count unit 8 is zero is equal to this reference speed value _Rp , the type is always accurately stopped at the printing position. It is a constant value depending on the number of movement steps.

In this way, the programmable delay circuit 37
The braking action of the stepping motor 6 during the homing period F is adjusted so that the type is accurately stopped at the printing position.

The delay values D ₂ and D ₁ of the registers 18 and 28 and the reference speed value R _p of the register 19 are formed in the data formation unit 45 as values corresponding to the specified number of movement steps, and are stored in the registers 18, 19 and 19, respectively.
28, and the modified delay amount _D1 stored in register 28 is returned to data forming unit 45 when the operation for that character is completed.

Note that when the comparator 31 detects that the count value M is zero, the programmable delay circuit 38 is reset. Due to this reset, the output level of the programmable delay circuit 38, which was at "L" immediately before this reset, is inverted to "H".
Therefore, this output level is determined by the rise of the delay signal _d1 from the programmable delay circuit 37.
Either it is delayed by T ₂ and inverted from "L" to "H", or it is inverted from "L" to "H" by the output signal of the comparator 31, and this inversion of the output level is caused by the count value M is never later than the point when becomes zero.

This is because if the phase of the hold pulse pattern H is changed after the count value M becomes zero, the torque will not become zero when the count value M is zero, but a large torque in the opposite direction will be generated, and the operation will be interrupted. This is to prevent errors from occurring.

Further, the movement end signal of the comparator 31 is supplied to the control unit 46, and after a certain period of time, the register 28,
The corrected numerical values stored in 29 and 30 are sent to the data forming unit 45.

The register 32 stores a value that determines the rotational direction of the stepping motor 6 (hereinafter referred to as rotational direction value), and controls the hold pulse pattern generator 9 to generate a hold pulse pattern H corresponding to the rotational direction.

FIG. 8 is a block diagram showing a specific example of the data forming unit shown in FIG. 6, in which 48 is a rotation angle setting unit, 49 is a block designation unit, 50 is an address generation unit, and 51 is a read-only memory (hereinafter referred to as 52 is a random access memory (hereinafter referred to as RAM), 53 is a multiplier,
54 is a divider, 55, 56 are output terminals, 57, 5
8 is an input terminal.

This embodiment operates under the control of control unit 46 (FIG. 6).

The rotation angle setting unit 48 is connected to the type wheel 1.
This is to set the rotation angle of the stepping motor required to move the specified type (Figure 1) to the printing position, that is, the number of movement steps, from the current position of the specified type and the printing position. The number of movement steps is calculated.

The block designation unit 49 designates the block to which the number of movement steps set by the rotation angle setting unit 48 belongs.

Now, the number of possible movement steps is X ₁ , X ₂ , X ₃ ,
. . , X _p , the number of movement steps is divided into, for example, Q blocks. That is, the number of movement steps is expressed as: Number of movement steps X ₁ ~ _{X i} → Block 1 Number of movement steps X _i+1 ~ X _{j →} Number of Block 2 movement steps X _{j +1 ~} Group them as follows: ₁ ~X _p →block Q. The block designation unit 49 determines whether the number of movement steps set by the rotation angle setting unit 48 is block 1, 2, 3, . . .
Among Q, it is determined which block it belongs to.

Numerical values corresponding to the respective movement step numbers are written in the ROM 51. Now, the modifiable values stored in the registers 29 and 30 in FIG. 6 are collectively referred to as variable data, and the pulse count unit 8
The preset values, the numerical values stored in registers 18 to 21, and the initial stage value stored in register 30 are collectively referred to as fixed data, and
If the numerical values stored in are called delayed data, then
In the ROM 51, fixed data and delay data are classified and written for each number of movement steps. Furthermore, in the ROM 51, for each block,
A magnification that forms variable data by calculation with the number of movement steps is written.

That is, block 1 → magnification α ₁ , β ₁ block 2 → magnification α ₂ , β ₂ block 3 → magnification α ₃ , β ₃ block Q → magnification α _Q , β _Q , and so on, each block has a magnification of 2. is compatible. The magnifications α ₁ , α ₂ , α ₃ , ..., α _Q are calculated using the number of movement steps in the register 29 (sixth
₎ , and the magnifications β ₁ , β ₂ , β ₃ , . Form numbers.

When the power is turned on, the RAM 52 is transferred to the ROM 51.
Fixed data and delay data are transferred from the block and stored separately for each number of movement steps, and the above-mentioned magnification is stored separately for each block, and these data and magnifications are read and written as desired. .

That is, when a predetermined number of movement steps is set by the rotation angle setting unit 48, the value of this number of movement steps is supplied to the block designation unit 49 and the address generation unit 50. The address generation unit 50 generates an address signal according to the set number of movement steps, and based on this address signal, fixed data and delay data for the set number of movement steps are read out from the RAM 50, and the output terminal 55, pulse count unit 8, registers 18 to 21, 28 (above,
(Fig. 6).

On the other hand, the block specifying unit 49 specifies the block to which the set number of movement steps belongs, and the address generating unit 50 thereby generates a predetermined address signal. Based on this address signal, the RAM 52 reads out the magnification for the designated block and supplies it to the multiplier 53.

The multiplier 53 is supplied with the number of moving steps set by the rotation angle setting unit 48 and the magnification from the RAM 52, and multiplies both to form variable data.
registers 29 and 30 via output terminals 56, respectively.
(Above, Fig. 6) is supplied. For example, now
If the set number of movement steps is X ₁ , this belongs to block 1 as described above, so
The magnifications α ₁ and β ₁ are read from the RAM 52. Therefore, the multiplier 53 multiplies X ₁ and α ₁ , supplies the obtained value X ₁ · α ₁ to the _register 29, and then
is multiplied by β ₁ and the obtained numerical value X ₁ ·β ₁ is supplied to the register 30.

As mentioned above, the variable data modified during the operation of the stepping motor 6 (FIG. 6) is supplied to the divider 54 via the input terminal 57 to each of the moving units set by the rotation angle setting unit 48. ,
Calculate the corrected magnification by performing division processing. For example, in the above example, the number of movement steps set is X ₁ , and the register 29 by the multiplier 53
Assuming that _the numerical value N ₁ ( _{= X 1} · α ₁ ) stored in Calculate ₁ ′. Similarly, the value N ₂ stored in register 30
(=X ₁ ·β ₁ ) is corrected to the value N ₂ ′, the divider 54 calculates a magnification of N ₂ ′/X ₁ =β ₁ ′. These corrected magnifications α ₁ ', β ₁ ' are supplied to the RAM 52 and written in place of the magnifications α ₁ , β ₁ of block 1.

Furthermore, after the operation of the stepping motor 6 is completed, the corrected delay data is transferred from the input terminal 58 to the RAM.
52 and written to the address corresponding to the set number of movement steps.

In this way, the modified fixed data, delayed data and scaling factors are used as data for the next same number of movement steps.

Each data read into the ROM 51 is determined according to the design characteristics of the stepping motor 6. The size of each block (i.e., the number of moving steps belonging to the block) is determined by the deviation (i.e., maximum value, minimum value) of the designed numerical values stored in registers 29 and 30 in the block. The magnification is the value obtained by dividing the designed values stored in registers 29 and 30 in the block by the number of movement steps corresponding to these values. shall be. This number of movement steps is particularly called the number of block reference movement steps.

By the way, the delay data and magnification transferred from the ROM 51 to the RAM 52 are transferred to the stepping motor 6.
These are design values determined according to the design characteristics of the registers 28 to 30.
Even if the stepping motor 6 is stored in the memory and corrected by driving the stepping motor 6, there will be no difference between the designed characteristics and the actual characteristics of the stepping motor 6, at least after the power is turned on. Since there is a possibility that there is a problem, the desired characters will not be set accurately at the printing position.

This problem can be solved by setting a certain period of time as a test period after the power is turned on, correcting the delay data and magnification during this test period, and performing the actual printing operation even with these corrected delay data and magnification. It will be resolved.

That is, in FIGS. 6 and 8, after the power is turned on, the rotation angle setting unit 48 sequentially sets the number of block reference movement steps for each block multiple times, and each time the number of block reference movement steps is set, Modify the scaling factor and delay data accordingly as above.

Then, when the magnification and delay data for each block reference movement step number are corrected multiple times, these magnification and delay data are considered to correspond to the actual characteristics of the stepping motor 6, and the correction operation is completed, and then , all the movement step numbers other than the block reference movement step number are sequentially set in the rotation angle setting unit 48 a plurality of times. Every time the number of movement steps is set, fixed data and delay data are read from the RAM 52 and supplied to the pulse count unit 8 and registers 18 to 21, 28.
Further, the above-mentioned corrected magnification is read out from the RAM 52 and supplied to the multiplier 52, and variable data is formed as described above to the registers 29, 30.
supplied to

The stepping motor 6 operates to correct the variable data and delay data, but the control unit 46
divider 54 is set to an inactive state by , so that only the modified delay data is
It is returned to the RAM 52 and written.

In this way, the delay data for each movement step number is corrected multiple times, and as a result,
The RAM 52 stores a magnification for the block reference movement step number and delay data for all movement step numbers including this movement step number, corrected to match the actual characteristics of the stepping motor 6. become. In this case, the variable data formed from the multiples is not accurate for the number of movement steps in the block other than the block reference movement step number, but the difference from the accurate variable data is even with the corrected delayed data. Therefore, by using such corrected data for every number of movement steps, the type will be accurately set in the printing position.

After modifying each data during the test period, when printing, divider 5 must be turned off unless the power is turned off.
4 is set inactive, the magnification is held constant, and only the delay data is modified for each printing operation.

As mentioned above, the data written to the memory unit consisting of the ROM 51 and RAM 52 includes fixed data and delay data corresponding to each number of movement steps, and a magnification for each block in which each number of movement steps is divided. The capacity of the memory unit is not particularly large, and combined with the delay data and variable data correction function, the rotation angle of the stepping motor 6 can be obtained with high precision for a specified movement step.

In addition, in the RAM 52, the address of the fixed data can be made common to each number of movement steps, and each time the number of movement steps changes, the fixed data for this can be read from the ROM 51 and written to the common address of the RAM 52.
The capacity of RAM 52 becomes even smaller.

Furthermore, the fixed data can be read directly from the ROM 51 and supplied to the pulse count unit 8 and each register.
It is also possible to reduce the capacity of 52.

Furthermore, the memory unit has register 3.
Needless to say, the rotation direction value to be stored in 2 is stored.

The control unit 46 controls the series of operations described above, and also resets the pulse count unit 8 and each register immediately after turning on the power or before starting each printing operation.

Next, the operation of this embodiment will be explained assuming that the number of movement steps required for printing is 19. In this case, as in the prior art described above, as shown in _{FIG .}
From high speed mode H _i to hold mode at step 1
_Hp , the hold mode _Hp is switched to the low speed mode _Lp at the 12th step, and further to the hold mode _Hp in which homing control is performed at the 17th step.

Now, as mentioned above, when the test period in which the data for each number of movement steps is corrected is over and the rotation angle setting unit 48 determines that the number of movement steps is 19, the control unit 46 sets the number of movement steps to 19. The data forming unit 45 reads out each numerical value for the pulse counting unit 8.
is preset to the value 19, and at the same time register 1 is preset to
Predetermined delay values D ₂ and D ₁ are stored in registers 8 and 28.
9, 20, 21 are predetermined reference speed values R _p , R _A , R _B
However, the value 11 is stored in the register 29, the value 20, which is larger than the preset value 19 of the pulse count unit 8, is stored in the register 30, and the value for setting the rotation direction of the stepping motor 6 is stored in the register 32. be done.

In this state, the hold pulse pattern generator 9 generates the hold pulse pattern H, the comparator 33 compares the count value M of the pulse count unit 8 with the reference value 2, and the comparator 34 compares the count value M with the register 29. The number N stored in ₁
(=11), and the comparator 35 outputs the count value M
is the numerical value N ₁ (=11) stored in register 29
and the numerical value N ₂ (=20) stored in register 30
Comparator 3
6 compares the count value M and the numerical value N ₂ (=20) stored in the register 30.

Here, since the count value M is 19, N ₂ (=20)>M (=19)> _N1 (=11)>2, and as mentioned earlier, the outputs of the comparators 33 and 35 The level is "L" and the output levels of the comparators 34 and 36 are "H". Therefore, and gate 1
6 and 40 are in a conductive state, and the AND gate 39 is in a cutoff state, so that the falling pulse signal a from the falling detector 13 can be supplied to the hold pulse pattern generator 9, and the “H” level of the comparator 36 is The output signal is supplied to the pulse converter 11 as a low speed command signal l _p . For this purpose, the pulse converter 11 converts the hold pulse pattern H to generate a low-speed drive signal c, and the stepping motor 6 rotates at a low speed to set the low-speed mode _Lp .

When the stepping motor 6 rotates one step and the falling edge detector 13 generates one falling pulse, the count value M of the pulse count unit 8 is
It becomes 18. At the same time, the pulse counting unit 8 sends a command signal to the control unit 46, which causes the control unit 46 to change the value to 20.
A value 17 is formed from the magnification in the RAM 45 and the movement step number 19 and is stored in the register 30. Therefore, the number N ₂ is 7.

Therefore, M>N ₁ (=11)>N ₂ (=7)>2, and the output level of the comparator 36, which was "H", becomes "L" and the AND gate 39 becomes conductive. For this purpose, the "H" output signal of the comparator 34 is supplied to the pulse converter 11 as a high-speed command signal h _i . As a result, the high speed mode H _i is set and the stepping motor 6 is accelerated and rotates at a high speed.

As the stepping motor 6 rotates at high speed, a falling pulse signal a is generated from the falling detector 13 and is supplied to the hold pulse pattern generator 9 and the speed detecting unit, where it is sent to the time/speed converter 15. The actual speed value R is generated from .

Then, the pulse count unit 8 subtracts the value by 1 each time a falling pulse is supplied, and when N ₁ (=11) ≧ M > N ₂ (= 7) > 2, it is determined that the pulse count is "H" until now. The output level of the comparator 34 becomes "L", and the output level of the comparator 35 becomes "L" instead.
The output level becomes "H". As a result, the hold command signal h _p is supplied to the pulse converter 11 and the hold mode H _p is set, and the stepping motor 6 is braked by the reverse torque and rotates at a reduced speed.

At the same time as the output level of the comparator 35 rises, the comparator 23 operates and compares the reference speed value R _A stored in the register 20 with the actual speed value R. Based on this comparison result, the arithmetic unit 26 generates an added value of +1, 0, or -1, and registers this added value after at least one step of the hold mode H _p has elapsed. 29 to modify the value stored there (11 in this case).

As the stepping motor 6 decelerates, the pulse count unit 8 further subtracts, and when N ₁ (=11)>N ₂ (=7)≧M>2, the comparator 35, which had been at “H”, The output level of the comparator 36 becomes "L", and instead, the output level of the comparator 36, which was previously "L", becomes "H".
Therefore, the low speed mode L _p is set, and the stepping motor 6 rotates at a low speed.

At the same time that the output level of the comparator 36 becomes "H", the comparator 24 operates to compare the reference speed value R _B stored in the register 21 with the actual speed value R. Then, similarly to the register 29, depending on these differences, after at least one step in the low speed mode L _p has passed, the numerical value N ₂ stored in the register 30 is changed.
(In this case, 7) is corrected by adding +1, 0, or -1.

When the stepping motor 6 further rotates and 2≧M, the output level of the comparator 33, which was previously “L”, becomes “H”, and the “H” output signal is passed through the OR circuit 41 as a hold command signal. It is supplied to the pulse converter 11 as h _p , and also turns off the AND gate 40. As a result, the hold mode H _p is set and the stepping motor 6
rotates at a reduced speed. At the same time, the output signal f is inverted by the inverter 44, and the AND gate 16 is cut off, thereby blocking the passage of the falling pulse signal a.

Furthermore, the output signal f of "H" is transmitted to the register 28.
The signal is supplied to the programmable delay circuit 37 with a delay amount T ₁ (FIG. 7) corresponding to the delay value D ₁ stored in the delay signal D _{1 , and is supplied to the hold pulse pattern generator 9 through the OR circuit 17 as a delay signal d 1} . Further, this delay signal d ₁ is supplied to a programmable delay circuit 38 with a delay amount T ₂ (FIG. 7) according to the delay value D ₂ stored in the register 18, and the delay signal d 1 is
It is supplied to the hold pulse pattern generator 9 through the OR circuit 17 as d ₂ . As a result, the hold pulse pattern generator 9 outputs delayed signals d ₁ ,
A hold pulse pattern whose phase is synchronized with the rising edge of _d2 is obtained.

Therefore, a reverse torque is generated in the stepping motor 6 according to the delay amount of the programmable delay circuits 37 and 38, and the brake is applied to decelerate the stepping motor 6, and finally it comes to a stop.

When the comparator 31 detects that the count value M of the pulse count unit 8 has become zero, the comparator 22 operates to compare the reference speed value R _p stored in the register 19 and the actual speed value R. compare. The arithmetic unit 25 calculates +1,
Either 0 or -1 is generated, and the delay value _D1 stored in the register 28 is modified with this value.

When the printing operation is completed, the control unit 46
The modified values stored in registers 28, 29, and 30 are transferred to data formation unit 45, but only the values from register 28 are written to RAM 52, as mentioned above.

As explained above, according to the present invention, it is possible to modify the data that defines the mode switching point of the stepping motor according to the characteristics of the stepping motor, and the rotation of the stepping motor at the mode switching point is The speed can be set to a specified value with high precision, which greatly improves the setting accuracy of the rotation angle of the stepping motor, and the number of data can also be significantly reduced. The capacity of the memory unit for storing the information can be reduced, and a stepping motor drive circuit with excellent functions can be provided without the drawbacks of the prior art described above.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing an example of a type wheel drive mechanism in a printer, Fig. 2 is a block diagram showing an example of a conventional stepping motor drive circuit, and Fig. 3 is an example of a stepping motor driving method. Figures 4a, b, and c are curve diagrams showing the torque in each mode of the stepping motor. Figure 5 explains the operation of the drive circuit in Figure 2 for the four-phase excitation stepping motor. FIG. 6 is a block diagram showing an embodiment of the stepping motor drive circuit according to the present invention; FIG. 7 is a timing chart for explaining the operation of the drive circuit of FIG. 6 during the homing period; FIG. 8 is a block diagram showing a specific example of the data forming unit shown in FIG. 6. 5...Sensor, 6...Stepping motor, 7
...Drive circuit, 8...Pulse count unit, 9...Hold pulse pattern generator, 11
...Pulse converter, 14...Pulse interval detector,
15... Time/speed converter, 20, 21... Register, 23, 24... Comparator, 26, 27... Arithmetic unit, 29, 30... Register, 33, 34, 3
5, 36...Comparator, 45...Data formation unit, 46...Control unit, 48...Rotation angle setting unit, 49...Block designation unit, 51
... Read-only memory, 52 ... Random address memory, 53 ... Multiplier, 54 ... Divider.

Claims (1)

[Scope of utility model registration request] A sensor that detects the rotational phase of the stepping motor, a hold pulse pattern generator, and a counter that counts pulse signals from the sensor.
A register unit in which data defining a mode switching point for a required rotation angle of the stepping motor is stored, and a comparison unit that compares the count value of the counter with the data to set the mode switching point. A drive for a stepping motor, wherein a hold pulse pattern from the hold pulse pattern generator is converted in accordance with an output signal of a comparison unit to form a drive signal for each mode of the required rotation angle of the stepping motor. The circuit includes a correction unit for correcting the data stored in the register unit, a memory unit for dividing all of the required rotation angles into a plurality of blocks and storing a magnification for each block, and a correction unit for correcting the data stored in the register unit; A rotation angle setting unit for setting a required rotation angle, a block specification unit for specifying the block according to the required rotation angle set by the rotation angle setting unit, and an arithmetic unit are provided. Arithmetic processing is performed on the required rotation angle set by the rotation angle setting unit and the magnification according to the required rotation angle unit, and the data defining the mode switching point of the stepping motor according to the required rotation angle is formed. At the same time, the data corrected by the correction unit is processed to form the corrected magnification, and the corrected magnification is stored in the memory unit, thereby adjusting the characteristics of the stepping motor. A stepping motor drive circuit characterized in that the mode switching point can be defined by the data modified accordingly.