JPH0724460B2 - Linear pulse motor - Google Patents

Description

The present invention relates to a linear pulse motor suitable for use in head feeding of a printer and the like.

[Conventional technology]

In recent years, with the development of digital technology, linear pulse motors (hereinafter referred to as pulse motors) driven by pulse voltage have been widely used. The circuit configuration is extremely simple and the position control accuracy is quite high, so that it has been favored as a driving means for an XY blocker, a printer head, and the like.

7 to 8 are diagrams showing the configuration of this type of pulse motor. In the figure, 1 is a scale, 2 is a slider, and the slider 2 moves on the scale 1. On the upper surface of the scale 1, scale teeth 3, 3, ... Are formed with a constant pitch τ. On the other hand, the slider 2
A pair of plate-shaped permanent magnets 5a, 5b fixed to the lower surface of the iron plate 4.
And a U-shaped core 6 fixed to the lower surface of each of the permanent magnets 5a and 5b.
a, 6b, and the cores 6a, 6b have four magnetic poles 11, 12, 13,
14 are formed. The magnetic poles 11 to 14 and the scale teeth 3 are
They face each other with a slight gear gap, and are displaced from the scale teeth 3 by 1/4 pitch in the order of the magnetic poles 11, 13, 12, and 14. Also,
A coil 7a is wound around the magnetic poles 11 and 12, and a coil 7b is wound around the magnetic poles 13 and 14.

The coils 7a and 7b are switching circuits 16 shown in FIG.
It is connected to the. The switching circuit 16 outputs the pulse output from the pulse distribution circuit 17. Driven by to excite the coils 7a and 7b.

FIG. 9 is a waveform diagram showing this excitation sequence.

First, when the clock CW in the positive direction is supplied to the pulse distribution circuit 17, pulses are output in the order of φ ₁ → φ ₂ → φ ₃ → φ ₄ , and the slider 2 is moved to the slider 2 shown in FIGS. Move by 1/4 pitch as shown in. That is, when the coil 7a is excited by the pulse φ ₁ (FIG. 7 (a)), the magnetic pole
The magnetic flux of 12 is weakened and the magnetic flux of the magnetic pole 11 is strengthened, and the magnetic pole 11 comes to a position directly above the scale teeth 3. Less than,
Similarly, the magnetic poles 13, 12, 14 are sequentially moved to the position directly above the scale teeth 3, and the slider 2 is moved in the positive direction (rightward in FIG. 7).

On the other hand, when the clock CCW in the reverse direction is supplied, the slider 2 moves in the reverse direction by the operation completely opposite to the above.

In this way, the slider 2 moves to the magnetically stable point and stops at each pulse, so that positioning in the oven loop becomes possible.

[Problems to be solved by the invention]

However, in the above-described conventional pulse motor, there is a problem in that the slider 2 causes damping vibration before and after the stop position, and the time (positioning time) until the stop is completed becomes unduly long.

For example, let τ be the pitch of the scale teeth 3, and FIG.
Displacement shown in Considering the case where the slider 2 is moved from the position of (1) to the position of χ = 0 shown in FIG. 7B, the slider 2 causes damping vibration around the position of χ = 0 as shown in FIG. ,
There is a problem that the positioning time T _s becomes long.

The reason for this will be described with reference to FIG. This figure shows the thrust-displacement characteristics of the pulse motor. When the displacement χ is negative, the thrust is positive, and when χ is positive, the thrust is negative.
Such characteristics are shown in FIG. 7 (a). When excited in the φ ₁ mode at the position, a positive thrust force acts on the slider 2 and the slider 2 moves in the direction of χ = 0.
However, since thrust is always positive in the negative χ region,
The slider 2 always overruns to a region where χ is positive, and does not stop unless negative thrust is applied. Therefore, the slider 2
Stops before and after χ = 0 while damping and oscillating.

As a result, when the head of the printer is driven by this kind of pulse motor, as shown in FIG.
Printing must be performed after the positioning time T _{s has} elapsed,
There was a problem that the printing speed became slow.

As a method of solving this problem, as disclosed in JP-A-52-62615, the induced voltage of the motor coil is detected, and the induced voltage is fed back to a control device for driving the motor coil to cause vibration. There are known methods for preventing the above. However, in the method disclosed in this publication, the speed electromotive force generated in the motor coil is directly detected, so that there is a drawback that reliability cannot be obtained unless an isolator having a high breakdown voltage is selected. Further, in this publication, it is assumed that the velocity electromotive voltage is detected when a current is passed in one direction like a rotary pulse motor, and the velocity electromotive voltage is passed when a current is passed in both directions like a linear pulse motor. Is not mentioned.

The present invention has been made in view of such circumstances, and an object thereof is to provide a linear pulse motor that can obtain a speed electromotive voltage with a simple configuration and high reliability.

[Means for solving problems]

In order to solve the above problems, the present invention includes a slider to which a motor coil is attached and a tooth-shaped scale arranged to face the slider, and feeds back a speed electromotive voltage generated by the slider movement to generate a pulse voltage command. In the linear pulse motor, which sequentially excites the motor coil by the difference between
A pair of cores coupled in series to the slider and arranged to face the scale, permanent magnets interposed between the cores, and a search coil wound around the magnetic poles of each core, and the permanent magnets having a magnetomotive force. And a speed electromotive voltage detecting means for generating a speed electromotive voltage proportional to a temporal change of the magnetic flux between the slider and the scale caused by the movement of the slider.

[Operation] According to the above configuration, when the slider moves, the magnetic flux between the slider and the scale having a permanent magnet as a magnetomotive force changes, and a velocity electromotive voltage is generated in each search coil. In this case, the velocity electromotive voltage is proportional to the temporal change of the magnetic flux between the slider and the scale.

Therefore, the velocity electromotive voltage in each direction can be obtained even when the current is passed in both directions of the motor coil without obtaining the velocity electromotive voltage from the induced voltage generated in the motor coil.

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

FIG. 1 is a block diagram showing the configuration of the main part of a pulse motor driving device according to an embodiment of the present invention. In this figure, the coils 7a, 7b of the slider 2 are power amplifiers 20a, 20b.
Respectively driven by. The voltage commands Ea ^* and Eb ^* of the A and B phases are supplied to the input terminals of the power amplifiers 20a and 20b, respectively, and the speed electromotive voltages Va and Vb of the A and B phases are supplied from the search coils 21a and 21b. Is fed back.

As shown in FIG. 2, the search coils 21a and 21b are wound around respective magnetic poles 24a and 24b of a pair of cores 23a and 23b which are serially coupled to the slider 2 by a non-magnetic coupling member 22. Has been done. These cores 23a and 23b are the core 6 shown in FIG.
It has the same dimensions as a and 6b, a permanent magnet 25 is interposed between the cores 23a and 23b, and the magnetic pole 24a is the magnetic pole 11 of FIG.
The magnetic poles 14b and the scale teeth 3 are in phase with each other. Then, when the slider 2 moves on the scale 1, the magnetic fluxes circulating in the cores 23a and 23b, the scale teeth 3 and the scale 1 change, and the speed electromotive voltages Va and Vb are generated in the search coils 21a and 21b.

For example, considering the case where the slider 2 moves from the position shown in FIG. 7A to the position shown in FIG. 7B, the search coils 21a and 21b are searched.
Sliders Va and Vb are formed in the direction to hold the position (a). That is, speed electromotive voltages Va and Vb in the opposite directions of the voltage commands Ea ^* and Eb ^* are generated, and these are fed back to the power amplifiers 20a and 20b. In other words, as shown in FIG. 1 (b), the slider 2 is in a state in which the power amplifier 20a (20b) has a negative feedback.

Next, the operation of this embodiment will be described with reference to FIGS.

As an example, from the position (χ = τ / 4) in FIG. 7 (a),
Consider the case of moving to the position (x = 0) of (b). In this case, as shown at time t ₁ in FIG. 3, when the B-phase voltage command Eb ^* is applied to the coil 7b, the forward thrust force shown by the solid line in FIG. Is χ = 0
Move in the direction of. By this movement, the search coil 21
Speed electromotive voltages Va and Vb are generated in a and 21b, and power amplifiers 20a and
Feed back to 20b. As a result, a negative exciting current Ia flows through the A-phase coil 7a, and a negative thrust force (braking force) acts on the slider 2 as indicated by the broken line in FIG.
Therefore, the slider 2 has a χ value as shown by the solid line in FIG.
Immediately stop at the position of = 0.

The current Ib flowing through the B-phase coil decreases due to the feedback of the speed electromotive voltage Vb. As a result, the positive thrust decreases and the braking action is promoted.

Thus, according to the present embodiment, quick positioning is performed at each step. Therefore, if this is applied to the positioning of the printer head, as shown in FIG. 6, it is more than the case of the conventional pulse motor (FIG. 12). Also, the printing speed can be increased.

〔The invention's effect〕

As described above, the present invention is provided with the slider to which the motor coil is attached and the tooth-shaped scale that is arranged so as to face the slider. The velocity electromotive voltage generated by the slider movement is fed back and the difference from the pulse voltage command is supplied. In a linear pulse motor in which the motor coils are sequentially excited by means of a magnet to generate a stepwise motion, a pair of cores connected in series to the slider and arranged to face the scale, and a permanent magnet interposed between the cores. And a search coil wound around the magnetic pole of each core, and a velocity generator that generates a velocity electromotive voltage proportional to a temporal change in the magnetic flux between the slider and the scale having the permanent magnet as the magnetomotive force, which is caused by the movement of the slider. Since it is equipped with voltage detection means, it is said that speed electromotive force can be obtained with a simple structure and high reliability. Effect can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing the construction of the essential parts of a pulse motor driving device according to an embodiment of the present invention, FIG. 2 is a front view showing the mounting state of search coils 21a and 21b, and FIG. 3 is the same embodiment. Waveform diagram of the voltage command of FIG. 4, FIG. 4 is a thrust-displacement characteristic diagram of the pulse motor according to the same embodiment, FIG. 5 is a diagram showing positioning characteristics of the pulse motor according to the same embodiment, and FIG. 6 is a pulse according to the same embodiment. FIG. 7 is a diagram showing the characteristics when the printer head is driven by a motor, FIG. 7 is a front view showing the configuration and operation of a conventional pulse motor, and FIG. 8 is a circuit diagram showing the configuration of a conventional pulse motor drive circuit. , FIG. 9 is a waveform diagram for explaining the operation of the conventional pulse motor, FIG. 10 is a diagram showing the positioning characteristic of the conventional pulse motor, and FIG. 11 is a diagram showing the thrust-displacement characteristic of the conventional pulse motor. , Fig. 12 shows a conventional pulse motor It is a figure which shows the characteristic at the time of driving a printer head. 1 ... Scale, 2 ... Slider, 7a, 7b ... Coil (motor coil), 20a, 20b ... Power amplifier (driving means), 21a, 21b ... Search coil 22 ... Coupling member, 23a, 2
3b: core, 24a, 24b ... magnetic pole, Ea ^* , Eb ^* ... voltage command (command value), Va, Vb ... speed electromotive voltage.

Claims (1)

[Claims] 1. A slider to which a motor coil is attached,
A linear scale is provided which is provided with a tooth-shaped scale opposed to the slider, feedbacks the velocity electromotive voltage generated by the slider movement, and sequentially excites the motor coil according to the difference with the pulse voltage command to generate a stepwise motion. In the pulse motor, the permanent magnet includes a pair of cores connected in series to the slider and arranged to face the scale, a permanent magnet interposed between the cores, and a search coil wound around a magnetic pole of each core. A linear pulse motor comprising: a speed electromotive voltage detecting means for generating a speed electromotive voltage proportional to a temporal change of a magnetic flux between a slider and a scale having a magnetomotive force as generated by the movement of the slider.