JPH10285995A - Stepping-motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve response by maximally shortening the time required for transfer from the state of the stoppage of a stepping motor to the state of rotation at constant velocity. SOLUTION: The device has initializing means 1, 18 for initializing the phase of a stepping motor 14 a voltage-fluctuation detecting means 20 for detecting voltage fluctuation from the stepping motor 14, and a decision means 1 for deciding the presence of the displacement of phase generated during the stoppage of the stepping motor 14 and starting the initializing means 1. 18 only when phase is displaced. The time required for starting the stepping motor 14 is shortened by detecting the change of phase generated owing to an external factor under the state of stoppage, in which no control signal is outputted to the stepping motor 14 at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling a step motor for driving a device such as a printer.

[0002]

2. Description of the Related Art Generally, when a step motor has a positional relationship (= phase) between the position of the magnetic pole of a permanent magnet and the position of a coil to be energized at the time of startup, the step motor temporarily causes reverse rotation. Since there is a possibility of step-out, it is necessary to determine the positional relationship between the two at the time of startup so that a predetermined coil corresponding to the magnetic pole position of the permanent magnet is excited.

For this reason, conventionally, when a step motor is driven, as shown in FIG. 8, initialization control is performed, and then control is shifted to desired constant speed control via acceleration control.

FIG. 8 shows an example of a control system in which a four-phase step motor is driven by two-phase excitation.

When the step motor is started for the first time from the stop state, first, the high level period T ₁ of the control signal for controlling the energization of the step motor is set to be larger than the pulse width T _{3 in} the case of the constant speed control. The motor is rotated relatively slowly so as not to have an extra inertial force by setting the motor, and initialization control is performed to first determine the relationship (= phase) between the magnetic pole position of the permanent magnet and the position of the energized coil. After the matching is performed by the initialization control, the high-level period of the control signal is gradually shortened to T ₂₁ > T ₂₂ > T ₂₃ to perform acceleration control for accelerating the motor. After the acceleration control performs constant speed control for rotating at a constant speed motor by adding a constant control signal having a pulse width T _3. As can be seen from FIG. 8, the control signals of the A phase and the C phase, and the control signals of the B phase and the D phase are each inverted in phase.
The phases of the phase control signals are controlled synchronously with the phases shifted sequentially.

In an information device such as a printer using a step motor, a control signal for controlling the energization of the step motor is not output at a predetermined phase due to a software program error or the like. Or the level of the control signal is reduced due to a hardware-like voltage fluctuation, and the control signal is not output at a predetermined phase. In this case, there is a possibility that the mechanical mechanism may be damaged. .

For this reason, in the prior art, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-87995, the difference between the phases of the control signal output to the stepping motor (see FIG. 8) is utilized. The motor is protected.

That is, a phase detection circuit having a logic circuit or the like for inputting control signals for each of the A-phase to D-phase is provided. If each control signal is not output at a predetermined phase, this phase An abnormality detection signal is output from the detection circuit to forcibly stop the step motor.

[0009]

However, the prior art disclosed in Japanese Patent Laid-Open No. 2-87995 has the following problem.

(1) Since the phase detection circuit determines whether or not the motor is abnormal based on the control signal output for controlling the energization of the step motor, when the control signal is not output, that is, when the step motor is External factors during outage
When the combination of the position of the permanent magnet and the position of the energized coil is misaligned due to (for example, when the stepper motor rotates accompanying the manual paper feeding of the printer), Not detectable.

Therefore, when the step motor is started,
It is necessary to always perform the phase matching control (initialization control) every time, and it takes time to control the stepping motor at a constant speed.

(2) Further, even when the printer is jammed or the like and the stepping motor cannot rotate smoothly, that is, when a so-called motor lock occurs, the control signal continues to be output. If there is no abnormality in the output phase, no abnormality detection signal is output from the phase detection circuit, so that the stepping motor cannot be stopped.

In order to eliminate such inconveniences and reliably detect the motor lock, conventionally, it is necessary to separately provide a dedicated motor lock detection sensor.
This will increase costs.

The present invention has been made in view of such a conventional problem, and detects a phase change caused by an external factor in a stop state in which a control signal is not output to a step motor. It is an object of the present invention to reduce the startup time as much as possible, and to detect the presence or absence of the motor lock of the step motor without providing a dedicated sensor as in the related art, thereby reducing costs. .

[0015]

The present invention employs the following structure to solve the above-mentioned problems.

That is, according to the first aspect of the present invention, there is provided a step motor control device, comprising: an initializing means for initializing a phase of a step motor; a voltage fluctuation detecting means for detecting a voltage fluctuation from the step motor; A determination means is provided for determining the presence or absence of a phase shift occurring during stoppage of the step motor in accordance with the detection output from the detection means, and for activating the initialization means only when a phase shift has occurred.

In this configuration, it is possible to detect whether or not a phase shift has occurred due to an external factor when the step motor is not controlled. Therefore, if the phase has not shifted, the initialization control is omitted. Can be.

According to a second aspect of the present invention, in the configuration of the first aspect, based on the detection output from the voltage fluctuation detecting means, it is determined from which phase the voltage fluctuation has occurred. Phase determining means, phase storing means for storing data of the phase determined by the phase determining means, and a phase to be started when the step motor is driven based on the phase data stored in the phase storing means. And phase determining means for determining

In this configuration, even if the phase shifts due to an external factor, the position of the phase of the step motor after the phase shift can be specified, so that the initialization control is performed more frequently than in the case of the first aspect. And the startup time can be further reduced.

According to a third aspect of the present invention, there is provided a stepping motor control device according to the first or second aspect, wherein the driving voltage measuring means measures a driving voltage during driving of the stepping motor, and the driving voltage measuring means. And a stop means for comparing the output of the step motor with a preset reference value, and when the drive voltage of the step motor falls below the reference value, determining that the motor is abnormal and forcibly stopping the step motor. .

In this configuration, since it is possible to detect that the step motor is locked due to paper jam or the like, it is not necessary to provide another dedicated sensor, and the cost can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, a case will be described in which the step motor control device of the present invention is used as a paper feeding device of a printer of an electronic cash register. However, the present invention is not necessarily applied to such a device. The present invention is not limited to the above and can be widely applied to a device having a step motor and a device for controlling the same.

FIG. 1 is a block diagram showing the overall structure of an electronic cash register.

This cash register machine stores a CPU 1 for controlling the operation of the entire apparatus, a ROM 2 in which various commands for controlling each peripheral device are stored in advance, and data and flags for controlling each peripheral device. RAM 3, keyboard 4 for inputting setting data, buzzer 5 for notifying when setting is completed or an error, display 7 for displaying key-input data, setting status, etc., communication I / F for infrared communication
(Interface) 8, a printer 9 for printing set data, device status, and the like, and a drawer 10 for storing money, checks, and the like.

FIG. 2A is an explanatory view showing a storage area inside the ROM 2, and FIG. 2B is an explanatory view showing a storage area in the RAM 3.

The ROM 2 includes an application program 2 ₁ for controlling the entire apparatus, a control data table 2 ₂ storing control data for driving the step motor, and a drive voltage measured when the step motor is driven. data table 2 ₃ where data is stored in the reference value for the compare whether normal or not, the measured message table 2 the data display data for notifying to that effect if an abnormal are stored Each of the storage areas ₄ is secured.

Further, the RAM 3, the display data buffer 3 ₂ for storing data buffer 3 ₁ for storing various setting values and flags during application operation, the data to be displayed, for storing print data print data buffer 3 _3, step motor voltage fluctuations that occurred during stop flag or a phase voltage variation data buffer 3 ₄ for storing the data of the measurement voltage for storing stores the voltage measured during step motor drive each storage area of the data buffer ₃₅ is ensured, respectively. And
This RAM 3 corresponds to the phase storage means in the claims.

FIG. 3 is a block diagram showing the configuration of the printer 9 and its drive control portion.

The printer 9 includes a print head 12 and a step motor 14 for feeding paper. Step motor 14
Is a two-phase excitation type four-phase step motor in this example, but the present invention can be applied to a three-phase or two-phase step motor.

The print head drive circuit 16 includes the CPU 1
Generates a drive signal according to a control signal given from
The print head 12 is driven by this drive signal.

The step motor drive circuit 18
Generates a drive signal by turning on / off a switching transistor (not shown) in response to a control signal as shown in FIG. 8 given from the CPU 1. This drive signal is generated by each coil of the step motor 14. The motor 14 is driven to rotate by flowing through L _{A to} L _D.

The voltage fluctuation detecting circuit 20 corresponds to a voltage fluctuation detecting means in the claims.
When the drive signal of the step motor is not output from
During the stop of the step motor 14, a voltage fluctuation generated in the step motor 14 due to an external factor is detected.

That is, for example, when the paper feed of the printer 9 is performed manually while the step motor 14 is stopped,
Along with this, a step motor 14 linked to a paper feed roller (not shown) rotates. And this step motor 1
4 rotates, each coil L _A by electromagnetic induction.
The ~L _D, as shown in FIG. 4 (a), each voltage is generated.
In the case of a two-phase excitation type four-phase step motor as in this example, these voltages are synchronously output with the phases of the A and C phases and the B and D phases reversed.

The voltage fluctuation detecting circuit 20 performs, for example, half-wave rectification of each signal based on these voltage fluctuations,
A detection output as shown in FIG. 4B is generated.

On the other hand, the voltage measuring circuit 22 corresponds to a driving voltage measuring means in the claims, and detects a voltage during drive control of the step motor 14.

[0036] That is, the printer 9 despite the step motor 14 for paper jam is in a state that can not be rotated, when the output of each phase of the control signal from the CPU 1, the interior of the coil L _A ~L step motor 14 _The back electromotive force acts on the _D portion, and the drive voltage is lower than the normal voltage. That is, as shown in FIG. 5, when the motor is locked, the voltage level shown in a solid line in FIG. 5 drops to the voltage level shown in a broken line in FIG. .

The voltage measurement circuit 22 measures the current drive voltage and outputs the measured value.

The switching circuit 24 selects the output of the voltage fluctuation detecting circuit 20 while the stepping motor 14 is stopped, based on the switching signal from the CPU 1.
4, the output of the voltage measurement circuit 22 is selected and C
It is sent to PU1.

The above-mentioned CPU1, ROM2 and RAM3 serve as initialization means in the claims, and the CPU1 and ROM2 serve as determination means, phase determination means and phase determination means in the claims.
All the stopping means are constituted.

Next, an operation when the stepping motor 14 is driven and controlled by the CPU 1 will be described with reference to a flowchart shown in FIG. 6 and a timing chart shown in FIG.

First, when the measurement start routine is entered (step 1), the CPU 1 executes the step motor drive circuit 18
It is determined whether or not the control signal is output at step (2), and it is determined whether or not the step motor 14 is stopped (step 2).

If the step motor 14 is stopped, C
PU1 switches the switching circuit 24 to select the output of the voltage fluctuation detection circuit 20, and determines whether or not there is a voltage fluctuation.
(Step 3).

That is, when the stepping motor 14 is rotated while the stepping motor 14 is stopped and the printer 9 is manually fed, for example, the coils L _{A to} L _D are applied to the respective coils L _{A to} L _D.
As described above, a voltage fluctuation occurs (see FIG. 4A), and a signal of this voltage fluctuation is input to the voltage fluctuation detection circuit 20, so that the circuit 20 outputs each signal based on these voltage fluctuations, for example. Half-wave rectification generates a detection output (see FIG. 4B). Then, this detection output is output to C
It is taken into PU1.

Therefore, the CPU 1 controls the step motor 14
If there is a detection output of the voltage fluctuation detection circuit 20 during the stop of
It is determined that there is a voltage variation as to set the flag for example to "1", and stores the data of the phase in which the voltage variation occurs in the voltage variation data buffer 3 ₄ RAM 3 (Step 4).

For example, as shown in FIG. 7, when it is assumed that the magnetic poles of the permanent magnet are in the C-phase and D-phase coils L _C and L _D at time t ₁ immediately after the stop of the step motor 14,
When a signal of voltage fluctuation is output from the C-phase coil L _C at time t ₂ because
This indicates that the magnetic poles of the permanent magnet have moved to the D-phase and A-phase coils L _D and L _A. Further, the motor 14 is rotated and the time t ₃
When the signal voltage variation from the coil L _D of the D-phase is output when it becomes indicate that poles of the permanent magnet is moved to the position of the coil L _A, L _B of the A-phase and B-phase. So, C
PU1, the final phase of the data (Fig. 7, A-phase and B-phase coils L _A, L _B in the data that the magnetic poles of the permanent magnets) to RAM3 voltage variation data in the stopped state of the stepping motor 14 after stored in the buffer 3 _4, the process proceeds to step 5.

If it is determined in step 3 that there is no voltage fluctuation, the process directly proceeds to step 5.

In step 5, for example, it is determined whether or not data such as a paper feed command is input from the keyboard 4 to determine whether to start the step motor 14. If the step motor 14 is not started, the process proceeds to step 3. Return. If the step motor 14 is to be started,
CPU1 checks the data in the data buffer 3 ₁ region of RAM 3, it is determined whether the flag of the voltage variation is already set to "1" (Step 6). In addition, CPU
In an initial state in which the power is first turned on for the first time, the voltage fluctuation flag is set to "1" in advance.

If the voltage fluctuation flag is not "1", it can be determined that the step motor 14 is not rotating at all from the state immediately after the stop, and thus the acceleration control is started immediately without the initialization control. Then, the process proceeds to the constant speed control (step 11). For example, when there is no any voltage fluctuation at time t ₁ after the immediately stopped in Figure 7, from the CPU 1, D phase and A
_A high-level control signal for exciting the phase coils L _D and L _A is output.

If the voltage fluctuation flag is "1" in step 6, the CPU 1 can determine that the step motor 14 has rotated due to an external factor during the stop state. data to determine whether it is already stored in the voltage variation data buffer 3 ₄ RAM 3 (step 8).

[0050] In my data phase voltage fluctuation has occurred already stored in the buffer 3 _4, it reads the data,
Based on this data, the drive start position of the step motor 14 is set (step 9), and the acceleration control is started from this phase to shift to the constant speed control (step 11). For example, as described above, when the effect of data that magnetic poles of the permanent magnets is stored in the coil L _A, L _B of the A-phase and B-phase at time t ₃ the voltage variation data buffer 3 ₄ RAM3 is, CPU 1 Outputs a high-level control signal for exciting the B-phase and C-phase coils L _B and L _C.

[0051] Further, if it is not the voltage variation data buffer 3 ₄ data phases stored in RAM3 in step 8, it is determined that the first initial state as the power is turned against the CPU 1, in FIG. 8 After the phase initialization control of the step motor 14 is performed (step 10), the acceleration control and the constant speed control of the step motor 14 are performed (step 11) in the same manner as in the conventional case shown above.

In step 12, for example, the keyboard 4
It is determined whether or not data such as a paper feed stop command has been input from the controller 10 to determine whether or not to stop the step motor 14, and if there is a stop command for the step motor 14, stop control of the step motor is performed (step 13). ). Then, it clears the data stored respectively in the data buffer 3 ₁ and the voltage variation data buffer 3 ₄ RAM 3 (step 14), and ends the process (Step 15).

On the other hand, if it is determined in step 2 that the step motor 14 is currently in the driving state,
U1 switches the switching circuit 24 to select the output of the voltage measurement circuit 22, and captures the value of the drive voltage measured by the voltage measurement circuit 22 (Step 17). Then, as compared with the reference value previously stored driving voltage to the drive voltage data table 2 ₃ ROM 2, it is determined whether a normal drive voltage (step 18). If the drive voltage is normal,
While the process proceeds to step 2, if the drive voltage is abnormal, the process proceeds to the motor lock process to forcibly stop the step motor (step 19), and ends the process (step 20).

In the above embodiment, the voltage fluctuation detecting circuit 20, the voltage measuring circuit 22, and the switching circuit 24 are provided. However, an A / D converter is provided in place of these circuits, and the step motor 14 is stopped. Signal of voltage fluctuation generated in
(See FIG. 4) and the drive voltage during step motor drive (FIG. 5).
Digitized into the CPU 1 and loaded into the CPU 1.
It is also possible to determine the voltage fluctuation during the stop of the motor and the drive voltage during the drive of the motor inside the CPU 1.

[0055]

According to the present invention, the following effects can be obtained.

(1) In the invention according to the first aspect, it is possible to detect whether or not a phase shift has occurred due to an external factor when the step motor is not controlled. The initialization control can be omitted, and the startup time can be shortened.

(2) According to the second aspect of the present invention, even if the phase shifts due to an external factor, the phase position of the step motor after the phase shift can be specified, so that the frequency of the initialization control is further increased. And the start-up time can be further shortened as compared with the case of the first aspect.

(3) According to the third aspect of the present invention, since it is possible to detect that the step motor is locked due to paper jam or the like, it is not necessary to provide another dedicated sensor, and the cost can be reduced. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram according to an embodiment in which a step motor control device of the present invention is used as a paper feed device of a printer of an electronic cash register.

FIG. 2 is an explanatory diagram showing contents of a ROM and a RAM provided in the electronic cash register.

FIG. 3 is a block diagram illustrating a configuration of a printer and a drive control device thereof.

FIG. 4 is a timing chart showing signals of voltage fluctuation.

FIG. 5 is a timing chart for explaining a difference in voltage level between a case where a step motor is normal and a case where an abnormality such as motor lock occurs.

FIG. 6 is a flowchart for explaining an operation when drive control of a step motor is performed.

FIG. 7 is a timing chart for explaining an operation when drive control of a step motor is performed.

FIG. 8 is a timing chart of a control signal for controlling a step motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CPU, 2 ... ROM, 3 ... RAM, 4 ... Keyboard, 7 ... Display, 8 ... Communication I / F, 9 ... Printer, 10 ... Drawer, 12 ... Print head, 14 ... Step motor, 16 ... Print head drive Circuit, 18: Step motor drive circuit, 20: Voltage fluctuation detection circuit, 2
2. Voltage measurement circuit, 24 switching circuit.

Claims (3)

[Claims] 1. An initializing means for initializing a phase of a step motor, a voltage fluctuation detecting means for detecting a voltage fluctuation from the step motor, and a step motor being stopped according to a detection output from the voltage fluctuation detecting means. A step motor control device comprising: a determination unit configured to determine whether or not a phase shift has occurred and to activate the initialization unit only when a phase shift has occurred. 2. The step motor control device according to claim 1, wherein: a phase determination unit that determines from which phase the voltage variation has occurred based on a detection output from the voltage variation detection unit; Phase storage means for storing data of the phase determined by the means, and phase determination means for determining a phase to be started when driving the step motor based on the phase data stored in the phase storage means. A step motor control device comprising: 3. The stepping motor control device according to claim 1, wherein the driving voltage measuring means measures a driving voltage during driving of the stepping motor, and the output of the driving voltage measuring means is set to a predetermined reference value. A step motor for determining that the motor is abnormal and forcibly stopping the step motor when the drive voltage of the step motor is lower than a reference value.