JPH05330168A - Method for controlling paper feeding motor - Google Patents

Abstract

PURPOSE:To provide an optimum control method which materializes the high resolution and high precision of paper feeding by the 1-2 phase driving of a stepping motor for paper feeding. CONSTITUTION:In the 1-2 phase excitation driving of a paper feeding motor, the fixed time of the final phase T0 for the final one-phase excitation and the fixed time of the final phase T4 for the final two-phase excitation are controlled to make T0 larger than T4, and a time chopping control 7 is conducted for a given time after the end of the final fixed time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a paper feed motor used in a printer.

[0002]

2. Description of the Related Art In recent years, serial printers have been used to print enlarged characters by high-density graphic printing or a combination of a plurality of print head scans and paper feed.
Paper feeding accuracy is a factor that greatly affects print quality. In other words, if the paper feed amount is larger than the proper value, white streaks are conspicuous, and conversely, if it is small, black streaks are conspicuous. Therefore, in the prior art, a high-resolution stepping motor is used to improve the paper feeding accuracy and prevent the occurrence of white lines and black lines.However, a high-resolution step motor is costly and the motor configuration is high. The yoke plate, which is a component, has a narrow plate width and is easily deformed when magnetic annealing is performed to remove residual magnetism, so that the resolution is naturally limited.

Therefore, in order to realize a higher resolution, the excitation state is switched between the two-phase excitation state (s2) and the one-phase excitation state (s1) as shown in FIG. , Realizes twice the resolution of the step motor itself.

FIG. 6 (a) shows the case of stopping in the one-phase excitation state, and FIG. 6 (b) shows the case of stopping in the two-phase excitation state. The final phase is the period Td from the final phase switching time Tlast. It is excited and switched to the holding current value and stopped.

[0005]

However, the above-mentioned conventional technique has the following problems.

When printing is performed in the one-phase excitation stopped state shown in FIG. 6A, black streaks occur, and when printed in the two-phase excitation stopped state shown in FIG. 6B, white streaks occur.

The generated torque in the two-phase excitation state is 2
It is the vector sum of the generated torques generated by the two drive coils, which is larger than the generated torque in the one-phase excitation state. That is, the torque generated by the one-phase excitation does not reach the predetermined rotation angle during the final-phase excitation time Td from the final-phase switching time Tlast shown in FIG. 6, so that Td should be lengthened. On the contrary, there is a problem that an extra energy key is input when the two-phase excitation is stopped and the motor itself generates heat.

The present invention has been made in view of such a problem, and an object thereof is to provide a stable paper feed control method regardless of an excited state.

[0009]

A method of controlling a paper feed motor according to the present invention is directed to a printing apparatus for feeding a paper by a 1-2 phase excitation drive of a stepping paper feed motor of a terminal printer equipped with a paper feed wheel train mechanism. In the control method, when stopping the stepping paper feed motor in the two-phase excitation state, after exciting the final phase for a first time from the final phase switching time, a current smaller than that during the first time is applied. Continue to flow and control to switch to current at stop after a predetermined time,
When stopping the stepping paper feed motor in the one-phase excitation state, after exciting the final phase for a second time longer than the first time from the time of switching the final phase, and further than the time of the second time. A control is performed to keep the small current flowing and to switch to the current at stop after a predetermined time.

[0010]

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

FIG. 1 is a schematic plan view of a mechanical portion of a terminal printer to which the present invention is applied.
Side frames 13 and 14 are attached to both sides of the upper surface of
The platen 3 is attached across the side frames 13 and 14. The platen 3 is a paper feed motor 2
Accordingly, the platen intermediate wheel 5 and the platen gear 4 attached near the end of the platen 3 on the central axis rotate.

In this apparatus, the platen gear 4, the intermediate gear 5, and the paper feed motor pinion 6 are used so that the minimum paper feed resolution is 360 DPI (dots / inch) for the paper on the outer peripheral surface of the platen 3. The reduction ratio of the constructed paper feed gear train mechanism is set to a predetermined value. FIG. 2 is an enlarged view of the paper feed train wheel unit at the top of FIG. (However, the upper and lower sides and the left and right sides are replaced with those in FIG. 1.) FIG. 5 is a publicly known circuit diagram for driving the above-described apparatus, and the phase data input terminal P of the control unit 1 and the paper feed drive circuit (not shown)
A to PD and a current switching signal terminal PH are electrically connected. When the motor is driven, the transistor Q5 is turned on by the input signal to PH, and each phase data terminal PA to PD
Based on the phase data signal input from the control unit 1 at a predetermined time interval, each of the phase driving transistors Q1 to Q4 is turned on.
Turn off and energize the drive excitation coil. The control operation of the device configured as described above will be described below.

FIG. 3 is an operation diagram when the paper feed motor of the printing apparatus according to the embodiment of the present invention is driven by the 1-2 phase excitation method. FIG. ) Indicates the case where the motor is stopped in the two-phase excitation state.

In FIG. 3 (a), when the final excitation phase of the deceleration control is the one-phase excitation state, the final phase switching time Tla
After exciting the final phase from st to T0 (for example, 12 to 14 μs), the exciting current energized state 8 and the holding current for supplying the exciting current to the exciting coils A to D of the paper feed motor 2 at the frequency of 2.8 to 3 kHz. The chopping control 7 is performed by alternately repeating the energization state 9 of the holding current for supplying. By this chopping control 7, a torque lower than that in the excitation current energized state 8 and higher than that in the holding current energized state is generated.

The chopping frequency is set so that the natural frequency including the stepping motor and the mechanical section does not cause resonance because it matches the frequency of the current of the exciting coil.
This is to be set in advance.

When stopping in the two-phase excitation state of FIG. 3 (b), it is the same as that of FIG. 3 (a), but in the two-phase excitation state, the generated torque is larger than that in the one-phase excitation, so that the final phase switching time Excitation of the final phase for a short T4 (for example, 2 to 4 μs), which is shorter than the one-phase excitation of Tlast, and then an excitation current is supplied to the excitation coils A to D of the paper feed motor 2 at a frequency of 2.8 to 3 kHz. The chopping control 7 is performed by alternately repeating the current energization state 8 and the holding current energization state 9 for supplying the holding current.

Here, the reason for performing the chopping control 7 in FIG. 3 will be described. In FIG. 3, when shifting from the deceleration control to the stop control, if the current of the exciting current energized state 8 is continuously supplied to the paper feed motor 2 in the final exciting step, as shown in FIG.
Due to the inertia of the paper feed train mechanism itself and the large generated torque of the motor 2, the paper feed train mechanism rotates too far from the stable position of the rotor (overshoot 10) and then tries to return to its original position (undershoot 11). Then, the generated torque is weakened after a time T8 from the time point of the final phase switching in FIG. 4, and further, after a time T9 when the rotor returns to the predetermined position, the generated torque is switched to a weaker holding torque to quickly suppress the damping and stop at the predetermined position. Can be made Further, since a large current is not applied to the exciting coil for a long time, heat generation of the exciting coil can be reduced.

[0018]

As described above, according to the present invention, it is possible to realize the paper feed control which is finer than the resolution of the motor itself with high accuracy and the minimum power consumption.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a mechanical portion of a terminal printer to which the present invention is applied.

FIG. 2 is an enlarged view of a paper feed wheel train unit.

FIG. 3 is an operation diagram illustrating an embodiment of the present invention.

FIG. 4 is a diagram showing the behavior of the rotor of the paper feed motor.

FIG. 5 is a drive circuit diagram of a paper feed motor.

FIG. 6 is an operation diagram illustrating a conventional example.

[Explanation of symbols]

 1 Control Unit 2 Paper Feed Motor 3 Platen 4 Platen Gear 5 Intermediate Gear 6 Paper Feed Motor Pinion 7 Chopping Control 8 Excitation Current Energization Signal 9 Holding Current Energization Signal 10 Overshoot 11 Undershoot 12 Base Frame 13, 14 Side Frame

Claims (1)

[Claims] 1. A method of controlling a printing apparatus in which a stepping paper feed motor of a terminal printer having a paper feed wheel train mechanism is fed by a 1-2 phase excitation drive, wherein the stepping paper feed motor is driven in a 2-phase excitation state. At the time of stopping, after the final phase is excited for a first time from the time of switching the final phase, a current smaller than that for the first time is kept flowing, and a control for switching to a stop current is performed after a predetermined time. When stopping the stepping paper feed motor in the phase excitation state, after exciting the final phase for a second time longer than the first time from the time of switching the final phase, it is smaller than that during the second time. A control method for a paper feed motor, characterized in that the current is kept flowing and a control is performed to switch to a current at a stop after a predetermined time.