JPS5854590B2 - Deceleration control device for electric motor for stopping at fixed positions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixed-position stopping motor, such as an electric motor that drives printing paper in a line printer, which feeds the printing paper to a predetermined position and stops it. The present invention relates to a deceleration control device that controls deceleration.

When printing paper is fed by an electric motor, if the printing paper is a single sheet, the weight of the paper is appropriate and there is no resistance in the paper path, so it is decelerated to a predetermined speed using an almost ideal deceleration curve as shown in front of the broken line in Figure 2. It becomes possible to stop at a certain position.

However, in the case of 6 copies of paper, which has a large number of copies, the braking is too effective due to the weight of the paper and the resistance of the paper path, resulting in a large position error when starting position control, and vibrations occur as shown by the solid line in Figure 2. Since the paper is moved and controlled in a fixed position, there is a problem in that it is difficult to fix the paper statically.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, correct for differences in motor deceleration caused by differences in load, and eliminate oscillatory movements in fixed position control.

The present invention is characterized in that the speed of the electric motor is detected during deceleration, and the motor is coasted for a predetermined period of time corresponding to the effectiveness of braking.

That is, if the braking is too effective, the coasting time is lengthened, and if the braking is not effective, the coasting time is shortened.

Hereinafter, the present invention will be described with reference to drawings showing embodiments.

FIG. 1 shows a paper feeding system to which the present invention is applied, in which printing paper 1 is fed by a tractor 2 having feeding pins that engage feeding holes provided on both sides thereof.

The tractor 2 is driven by an electric motor 5 via a drive shaft 3 and a timing belt 4.

An encoder 6 is installed on the shaft of the electric motor 5 to generate a position pulse whenever the electric motor 5 rotates by a predetermined unit angle.

The position pulses generated by the encoder 6 are fed back to the electric motor 5 via the control circuit 7.

As shown in FIG. 2, the electric motor 5 is controlled by a control circuit I for acceleration, constant speed, deceleration, and fixed position to feed the printing paper 1 to a predetermined position.

That is, after the electric motor 5 is accelerated, a pulsed voltage sufficient to overcome the frictional force of the paper feeding system is applied to rotate at a constant speed, and when it approaches a predetermined distance from the target position, it is forcibly braked by reverse braking, and then further moved to the target position. is controlled for positioning just before.

However, as mentioned above, if forced braking is performed uniquely regardless of the load, vibrations may occur as shown by the solid line in FIG. 2 depending on the load.

For this reason, the present invention is characterized in that, as shown in FIG. 3, the speed of the electric motor 5 is detected during deceleration, and a coasting time corresponding to the detected speed is provided.

Note that the position pulses in FIG. 3 are for six copies of paper.

FIG. 4 shows an embodiment of a configuration for creating a deceleration signal with such coasting time set in the middle, where the signal DECCEL is a deceleration command, the signal ENCODER is a position pulse from the encoder 6, and the signal CLOCK is not shown. Clock pulses from the oscillator, signals BRAKE1 and BRAKE2
are deceleration signals before coasting and after coasting, respectively, and signal BRAKE is a deceleration signal.

Note that it is assumed that after the 133rd position pulse is generated after entering the deceleration control, the control is shifted to the fixed position control.

When the constant speed control is finished and a deceleration command DECCEL is generated, the flip-flop 22 is set via the differentiating circuit 19 to generate a deceleration signal BRAKE1, which brakes the electric motor 5 in reverse via the control circuit 7 and a drive circuit (not shown). .

In addition, the Nant gate 11 opens its gate and the position pulse E
Apply NCODER to the clock terminal of counter 20.

When counter 20 counts the fifth position pulse ENCODE, Nant gate 14 opens and resets and sets flip-flops 22 and 23, respectively.

As a result, the deceleration signal BRAKE1 disappears, and the electric motor 1 enters a natural deceleration state, that is, a coasting state.

In addition, the output UPCOUNT of the flip-flop 23 causes the Nant gate 12 to open its gate, and the clock pulse CLOCK is applied to the UP terminal of the reversible counter 21.
It is counted up.

When the counter 20 counts the eighth position pulse ENCODER, the flip-flops 23 and 24 are reset and set via the inverter 18, respectively.

As a result, the Nant gate 12 closes its gate and the reversible counter 21 stops counting up.

That is, the reversible count 21 is the position pulse ENCODE.
The time t1 from the fifth to the eighth R is detected, and as a result, the effectiveness of the braking, that is, the speed of the electric motor 5 is detected.

Further, the Nant gate 13 opens its gate, and the reversible counter 21 counts down by the clock pulse CLOCK.

When time t2 (-tl) elapses and the count value of reversible counter 2.1 becomes 0, OR gate 16 opens and resets and sets flip-flops 24 and 25, respectively.

By resetting the flip-flop 25, the deceleration symbol BRA
KE2 occurs, and the electric motor 5 enters the braking state again.

That is, the electric motor 5 coasts for a time of t1+t2 (=2t1).

Since these times t1 and t2 change in accordance with the speed of the electric motor 5 during deceleration, as a result, the electric motor 5 has a coasting time corresponding to the speed.

When the counter 20 counts the 133rd position pulse ENCODER, the Nantes gate 15 opens its gate, resets the flip-flop 25, and outputs the deceleration signal BRAKE.
2 and move to fixed position control.

Therefore, the deceleration signal BRAKE and the voltage applied to the motor 5 are as shown in FIG.

As described above, the present invention provides a coasting time corresponding to the motor speed during deceleration and compensates for differences in deceleration caused by differences in load. Vibratory movements can be eliminated.

In addition, in the description of the above embodiment, the coasting time t1
Although it is assumed that and t are equal, during this coasting time, resistance such as frictional force acts and deceleration occurs, so t2-t1+α
Ideal deceleration characteristics may be obtained by setting τ (τ = period of clock pulse CROCK, α = positive integer), but in this case, a configuration like the one shown in Figure 6, which shows only the necessary parts, may be used. And it is sufficient.

In FIG. 6, reference numeral 61 denotes an oscillator that starts oscillating by the output of a differentiating circuit 62 that differentiates the falling edge of the output pulse of the inverter 18, and stops oscillating after α pulses having the same period as the clock pulse CLOCK are generated.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram showing a paper feeding system to which the deceleration control device of the present invention can be applied, Fig. 2 is a characteristic diagram of paper feeding speed according to a conventional method;
Fig. 3 is a characteristic diagram of the paper feed speed by the deceleration control device of the present invention, Fig. 4 is a block diagram showing an embodiment of the configuration for creating a deceleration signal, Fig. 5 is a time chart, and Fig. 6 is It is a main part block diagram which shows another Example. In the figure, 5 is a motor, 6 is an encoder, 7 is a control circuit, 1
1 to 15 are Nant gates, 16 is an OR gate, 17 is a NOR gate, 18 is an inverter, 19 and 62 are differentiating circuits,
20 is a counter, 21 is a reversible counter, and 22 to 25 are flip-flops.

Claims (1)

[Scope of Claims] 1. An electric motor for stopping at a fixed position, which is subjected to acceleration control, constant speed control, deceleration control by forced braking, and fixed position control to send a load to a predetermined position and stop it. The motor includes an encoder that is attached to the rotating shaft of the motor and generates one position pulse every time it rotates by a predetermined angle, and a control circuit that feeds back the position pulses from the encoder to control the operation of the electric motor, and starts the deceleration control. A predetermined number N3 from
A counting means for counting the position pulses from the start of the deceleration control, and a counting means counting a predetermined number N1 (N1<N3), means for generating a braking stop signal to stop forced braking, and the counting means starts measurement when counting a predetermined number N1, and counts a predetermined number N2 (N1<N2<N3) from counting the predetermined number N1. and a measuring means for measuring the time until approximately twice the time elapses, and generating a signal to restart forced braking, and coasting for a predetermined time corresponding to the speed during deceleration control. A deceleration control device featuring: