JPH0348755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a step motor control device that uses both one-phase excitation and two-phase excitation to move a mover to a target position and then stop it.

[Prior art]

The minimum travel distance of a step motor's armature is generally limited by the mechanical accuracy of the motor itself. Therefore, if high-precision transition is required, use a high-precision motor with a large number of pole teeth or a hybrid motor.
The minimum travel distance has been reduced by using a motor with a small step angle, such as a PM type motor, or by controlling the motor by 1-2 phase excitation.

However, high-precision motors and hybrid PM type motors are expensive. In control using 1-2 phase excitation, when stopping the mover at the 1-phase excitation position, 1-phase excitation requires a greater force to move the mover based on excitation than 2-phase excitation, or to hold the mover at the stopped position. Since the force acting on the movable member is weak, the inertia of the movable member caused by continuous movement causes a relatively large oscillatory movement of the mover about the stop position. This oscillating motion is then damped and stopped by the excitation force and mechanical frictional force, but here too the stopping position changes depending on the initial magnitude of the inertial force, and it is difficult to accurately locate the target stopping position. This is extremely inconvenient for highly accurate movement of the movable element, with large variations in the stopping position.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a step motor control device which eliminates the above-mentioned conventional difficulties and enables highly accurate shifting with a simple configuration and without increasing costs.

[Configuration of Example]

Hereinafter, with reference to FIG. 1, the structure of an embodiment in which the present invention is applied to a step motor for a carriage of a printer will be described.

In the figure, the external host device such as computer 1 is the central processing unit (hereinafter referred to as CPU) in printer 2.
(referred to as ) 3. Further, the carriage 4 on which the type wheel and the printing hammer are mounted is attached to the movable element of a linear type carriage step motor 5, and the carriage step motor 5 is connected to the CPU 3 via a motor drive circuit 6. There is. Furthermore, a carriage step motor 5
A position detection device 7 connected to the CPU 3 is attached to the . This position detection device 7 is fixed to a stator so that a light emitting diode as a light emitting element and a phototransistor as a light receiving element can be moved as the movable element of the carriage step motor 5 moves, that is, as the carriage 4 moves. It is attached to the carriage with multiple slits in between.
The light emitted from the light emitting diode is received by a phototransistor of a light receiving element mounted on the opposite side of the light emitting diode through a plurality of slits fixed together with the stator of the carriage step motor 5. The configuration is such that an output signal from this phototransistor is sent to the CPU 3. Additionally, there is a ROM (read-only memory) 8 in which programs for each process are stored, a line buffer 9a in which data input from the computer 1 is temporarily written, and transfer buffers 9b and 2 in which the amount of carriage transfer is stored.
A working buffer that functions as an auxiliary transition buffer 9c, etc., which is set to 1 when the motor stops at the phase excitation position and then advances to the one-phase excitation position again.
RAM (readable and writable memory) 9 is
Connected to CPU3.

[Operation of the embodiment]

The operation of the above configuration will now be described with reference to FIGS. 1 and 2.

The data input from the computer 1 is first written into the line buffer 9a of the RAM 9, and processes such as printing, paper feeding, ribbon feeding, etc. are executed based on these data in the order in which they were input. Then, the next new data from the computer 1 is written again to the address where the already processed data has been written in the line buffer, and is sequentially processed in the same manner as described above.

Next, carriage migration based on data input from the computer 1 will be explained in detail with reference to FIG.

If the next data to be processed written in the line buffer 9a is carriage transfer data, first, in step 21, a value corresponding to the amount of transfer of the carriage 4 based on the data, that is, the movable part of the carriage step motor 5 is The amount of migration of
Write to the migration buffer 9b of RAM 9 and clear the auxiliary migration buffer 9c. Next, the process proceeds to step 22, where it is determined whether the amount of transfer is greater than the amount of transfer corresponding to the three characters. here,
If not, the process goes to step 23, where the carriage step motor is driven by 1-2 phase excitation control to move the carriage to the desired final stop position, and then the process goes to step 30. on the other hand,
In step 22, if the amount of movement of the mover is greater than the amount of movement corresponding to the three characters, the process proceeds to the next step 24, and the desired final stop position is 1.
It is determined whether or not the position is for phase excitation. Here, if the position is one-phase excitation, proceed to the next step 25.
Then, 1 is subtracted from the value of the transfer buffer 9b. Next, proceed to step 26 and complete the auxiliary transition buffer 9.
Write 1 to c. Next, the process proceeds to step 27, in which the mover is moved by the value of the transfer buffer 9b, and the carriage 4 is transferred. Next, the process proceeds to step 28, and stops when the transfer of the carriage 4 based on the value of the transfer buffer 9b is completed. That is, when the final target position is the one-phase excitation position, the movable element of the carriage step motor 5 temporarily stops at the two-phase excitation position one position before the final target position. Next, the process advances to step 29, where the mover advances by the value of the auxiliary buffer 9c, that is, by one step, and reaches the final target position, ie, the one-phase excitation position, before proceeding to the next step 30. On the other hand, if the desired final stop position is the two-phase excitation position in step 24, the process goes to step 23, and the mover moves to the transition buffer 9.
The process moves continuously by the value of b, that is, to the final stop position, and then proceeds to step 30. In step 30, the mover of the carriage step motor 5 that has reached the final stop position is energized by 1-phase excitation if the stop position is a 1-phase excitation position, or by 1-phase excitation if the stop position is a 2-phase excitation position. Stopped by two-phase excitation,
Hold it in that position. As a result, the carriage 4, which is attached to the movable element and moves together with the movable element, is also held at the intended stop position.

Further, since the carriage 4 is moved while checking the current position of the carriage step motor 5 using the position detection device 7, step-out can be prevented.

In the above embodiment, even if the desired final stop position is the 1-phase excitation position, if the amount of transition is up to 3 characters, the motor must be temporarily stopped at the 2-phase excitation position one position before. The motor continuously moves to the final stop position of 1-phase excitation, but
There is no problem in omitting the judgment at step 22 in FIG. 2 and performing control such that the motor always stops at the two-phase excitation position and then moves to the next one-phase excitation position as needed.

Furthermore, since the above embodiment applies the present invention to the carriage step motor 5 of the printer 2, a linear step motor is described, but a circular step motor in which a movable member rotates can be controlled by a similar control device. It is possible to do so.

〔Effect of the invention〕

As detailed above, the step motor control device according to the present invention can stop the mover in either the 1-phase excitation position or the 2-phase excitation position, so it is possible to set the minimum transition distance short. It is. In addition, when stopping the mover at a one-phase excitation position where the force to move the mover based on excitation is weaker than in two-phase excitation, it is possible to temporarily stop the mover at the two-phase excitation position one position before it. , the inertial force of the mover due to the continuous movement up to that point disappears, and then one-phase excitation is performed again to move the mover one step to reach the original target position 1.
Regardless of the amount of movement of the mover to the phase excitation position, it can always be accurately stopped under the same conditions. Therefore, the movable element can be easily moved with high precision without particularly providing a new device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a flowchart thereof. In the figure, 3 is a central processing unit, 5 is a carriage step motor, 6 is a motor drive circuit, and 8 is a
ROM, 9 is RAM, 9a is line buffer, 9
b is a transfer buffer, and 9c is an auxiliary transfer buffer.

Claims (1)

[Scope of Claims] 1. In a control device for a step motor using a 1-2 phase excitation method in which a mover is moved to a target position and stopped using both one-phase excitation and two-phase excitation, the purpose of the moving mover is: a determining means for determining whether the position is a one-phase excitation position or a two-phase excitation position; and when the determining means determines that the target position of the movable element is a two-phase excitation position. , first control means for continuously moving the movable element to a target position; and when the determining means determines that the target position of the movable element is a position of one-phase excitation, the movable element is moved. and second control means having an auxiliary transfer means for moving the movable element to the target position after the operation of the stop means is completed. A step motor control device characterized by: