JPS5928157B2 - Pulse motor excitation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation circuit for a pulse motor that prevents vibrations generated during step feeding of the pulse motor.

Conventionally, as a method for preventing vibration during step feeding of a pulse motor, for example, in the case of two-phase excitation shown in FIG. , phase switching pulses P, P2, P3, which instruct the step feed of the pulse motor.
A known method is to synchronize the current to the stator windings of each phase.

In other words, if the waveforms of the excitation currents φ1, φ2, φ3, and φ4 are made into a panorama of rectangular waves shown by dotted lines, transient vibrations will occur at the rise and fall of the waves, which is undesirable. It is driven by a trapezoidal wave.
However, in order to drive the trapezoidal wave, closed-loop control is used in which the displacement acceleration of the pulse motor is fed back to the control section to control the excitation current.

Therefore, an acceleration detector, an A/I converter, and a D/A converter were required, as well as a linear amplifier to suppress the excitation current, which was not only complicated and expensive but also had poor power efficiency. . This invention has been made in view of the above circumstances, and includes a pulse generation circuit that outputs a first pulse train whose duty ratio increases sequentially and a second pulse train whose duty ratio sequentially decreases, and an excitation current supplied to a pulse motor. A control circuit detects the phase of the corresponding excitation pattern, outputs the first pulse train when the excitation pattern rises, and outputs the second pulse train when the excitation pattern falls; The excitation pattern modulation circuit modulates the excitation pattern, and the driver circuit pulse-amplifies the modulated excitation pattern to drive the pulse motor. The excitation current is modulated by a pulse train in which the duty ratio increases or decreases sequentially at the rise and fall of the excitation current.

It is an object of the present invention to provide an excitation circuit for a pulse motor that can prevent vibration of a pulse motor using open-loop digital control, simplify the circuit configuration, and improve power efficiency. It's about doing. Furthermore, another object of the present invention is to provide an excitation circuit for a pulse motor that allows easy and quick adjustment of the circuit required to prevent vibration of the pulse motor. The present invention will be described below based on embodiments shown in the drawings.

FIG. 2 is a block wiring diagram showing the configuration of an embodiment in which the present invention is applied to a two-phase excitation pulse motor, and reference numeral 1 in the figure indicates an n-digit ring counter. Ring counter 1 has its nth digit output terminals Qn and Qn as shown below.
The pulse train is configured to output a first pulse train whose duty ratio sequentially increases and a second pulse train whose duty ratio sequentially decreases. That is, a clock pulse is input to the clock input terminal T of the ring counter 1, and the reset terminal R is input to the clock input terminal T of the ring counter 1.
Phase switching pulses Rl, R2, R3, etc., which instruct the step feed of the pulse motor, are input to D, and
The signals output to the n-th and n-1st digit output terminals Qn and QO-1 of the ring counter 1 are respectively input to the 0R gate 2, and the 0R gate 2 is further provided with the above-mentioned phase signals. Switching pulse Pl, P2, P3...
The Q output of the flip-flop 3 is inputted as the set input and the output of the first digit of the ring counter 1 is the reset input, and the output of this 0R gate 2 is input to the input terminal of the first digit of the ring counter 1. Supplied. The first pulse train and the second pulse train, which are the n-th digit outputs of the ring counter 1, are supplied to the gate circuit 41 of the control circuit 4. Note that the ring counter 1, 0R gate 2, and flip-flop 3 described above constitute a pulse generation circuit. This control circuit 4 is composed of the gate circuit 41 and the phase detection circuit 42, and has excitation patterns φ1 and φ2 corresponding to the excitation current supplied to the pulse motor.
, φ3, φ4 by the phase switching pulses Pl, P2, P
The gate circuit 41 is controlled by the output of the phase detection circuit 42 detected at the time of input of the signal 3. The first pulse train or the second pulse train is input to the excitation pattern modulation circuit 5 through this gate circuit 41, modulates the excitation pattern, and then modulates the modulated excitation patterns φ, M, φ2M, φ3M, φ4M. The driver circuit 6 amplifies the pulse and excites the pulse motor 7. In addition, the excitation pattern φ mentioned above
1 φ・2, φ3, φ4 are movement signals of the pulse motor 7 before the rise and fall are modulated by the first pulse train and the second pulse train, and are shown by dotted lines in FIG. The square wave pulses φ1, φ2, φ3, and φ4 are shown. Next, the operation of the pulse motor excitation circuit constructed as described above will be explained.

First, the operation of ring counter 1 will be explained.

Phase switching pulse is n-digit ring counter 1 set terminal R
When input to D, this ring counter is reset. At the same time, the phase switching pulse is supplied to the set terminal of the flip-flop 3, so the flip-flop 3 is set, and its Q output is sent via the 0R circuit 2 to the input of the first digit of the ring counter 1 as a binary logic circuit. Write "I" of. When the first clock pulse is supplied to the clock input terminal T, the flip-flop is reset. After this, in synchronization with the clock pulse, the first digit "l"
is transferred to the second digit, third digit, etc., but the output of the n-1st digit and the nth digit is 0R.
Since the digit is returned to the first digit via gate 2, the number of digits of "I" written into ring counter 1 increases by 1 every time the clock pulse is inputted n times. As a result, a first pulse train whose duty ratio sequentially increases and a second pulse train whose duty ratio sequentially decreases are outputted to the n-th digit output terminals Qn and On, respectively. These first pulse train and second pulse train are then supplied to the gate circuit 41 of the cape control circuit 4. On the other hand r excitation 7゜turn φDφ2ra φ3yφ
4: In this embodiment, as shown in FIG. 1, when the phase switching pulse P1 is input, φ2 and φ3 are turned on, and when P2, φ3 and φ4 are input, and when P3, φ4 and φ1 are turned on.
, P4, φ1 and φ2 are turned on sequentially to control the step feed of the pulse motor 7, and when switching these phases, a phase detection circuit detects whether the phase of the excitation pattern is rising or falling. Detected by 42.

By the output of this phase detection circuit 42, the gate circuit 41
When the excitation patterns φ1, φ2, φ3, and φ4 rise, the excitation patterns φ1, φ2, φ3, and φ4 are modulated by the first pulse train that sequentially increases the duty ratio, and when they fall, the excitation patterns φ1, φ2, φ3, and φ4 are , the excitation patterns φ1, φ2, φ3, φ4 are modulated by a second pulse train whose duty ratio is sequentially decreased, and a modulated excitation pattern φ as shown in FIG.
1M, φ2M, φ3M, and φ4M are output from the excitation pattern modulation circuit 5. Then, this output is sent to the driver circuit 6.
The pulse width is amplified by , and an excitation current is supplied to the pulse motor 7 to excite it. In other words, this means that the rising and falling edges of the excitation current supplied to the pulse motor 7 are stepped by pulses that sequentially increase or decrease the duty ratio, equivalently approaching a trapezoidal wave or drive, which occurs during step feeding. This prevents vibration. Furthermore, data examples and vibration prevention effects when the pulse motor excitation circuit according to the present invention is applied to a paper feed pulse motor of a printer are as follows.

Key As is clear from the configuration and operation of the embodiments described above, the present invention allows the rise and fall of the excitation current supplied to the pulse motor to be controlled by first and second pulse trains in which the duty ratio increases or decreases sequentially. Since the excitation circuit of the pulse motor can be digitally controlled in an open loop, the circuit configuration can be simplified and power efficiency can be improved.

Furthermore, in order to prevent vibrations, it is necessary to set the optimal rate of increase or decrease in the duty ratio according to fluctuations in the load or rotational speed of the pulse motor. Since the drive is driven by the following, it has the advantage that the circuit can be adjusted easily and quickly.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the time relationship between phase switching pulses and excitation patterns, Fig. 2 is a block wiring diagram showing an embodiment of the excitation circuit of a pulse motor according to the present invention, and Fig. 3 is an implementation of Fig. 2. It is a figure which shows the time relationship of the phase switching pulse and the modulated excitation pattern in an example.

Claims (1)

[Claims] 1 a ring counter triggered by a clock pulse and reset by a phase switching pulse;
a flip-flop that is reset by a signal obtained at the 1 output terminal, and Q_n_-_1 of the ring counter.
The output terminal, the Q_n output terminal, and the Q output terminal of the flip-flop are each input with the obtained signals, and the output is supplied to the signal input terminal of the ring counter. A pulse generation circuit outputs a first pulse train and a second pulse train whose duty ratio decreases sequentially, and detects the phase of an excitation pattern corresponding to the excitation current supplied to the pulse motor. a control circuit that outputs the first pulse train and outputs the second pulse train at the falling edge; an excitation pattern modulation circuit that modulates the excitation pattern according to the output of the control circuit; A pulse motor excitation circuit comprising a driver circuit that amplifies and drives the pulse motor.