JPH0515138A - Linear pulse motor - Google Patents

Abstract

PURPOSE:To provide a position detector which can inexpensively detect the relative positional relation between a needle and stator with a simple constitution without changing the structure of a linear pulse motor. CONSTITUTION:This linear pulse motor is constituted of a stator 2 and needle 3 and an external position detector 20 is fitted to the side face of the stator 2 in the moving direction of the needle 3. The detector 20 is composed of a light emitting and receiving sections and detects the recessing and projecting sections of magnetic pole teeth 8 formed on the needle 3. Since the pole teeth 8 formed on the needle 3 are used as a scale, a linear pulse motor which is provided with an inexpensive position detecting mechanism having a simple constitution can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear pulse motor used in a magnetic head driving device for a floppy disk drive.

[0002]

2. Description of the Related Art A linear pulse motor can be considered as a linear expansion of a stator and a rotor of a general rotary motor, and is driven according to a given pulse signal. However, the motor cannot be driven at a pulse rate higher than the self-starting frequency, so if the position of the magnetic pole teeth of the mover during movement is detected and a signal is given in advance, it will be driven at a speed several times faster than when open. You can

An example of a conventional linear pulse motor is shown in FIG. The linear pulse motor 1 has a mover 2 that moves on a scale 8 having magnetic pole teeth, a magnetic pole tooth 33 attached to the mover 2, and a coil 32 wound around the magnetic pole tooth 33.

When the mover 2 moves, an induced voltage is generated in the coil 32 wound around each magnetic pole tooth 33.
By detecting this induced voltage, the position of the mover 2 can be detected. FIG. 8 is a block diagram showing a configuration of an example of a detection circuit for detecting the position of the mover 2, and the oscillator 34 supplies a high frequency signal to each of the coils 32a to 32d. The pitch of the magnetic pole teeth 33 is formed to be 1.5 times the pitch of the magnetic pole teeth of the scale 8, and the difference between the induced voltage generated in the coil 32a by the subtractor 37a and the induced voltage generated in the coil 32c is calculated. Detected, rectified by the synchronous rectification circuit 35a, and further low-pass filter (LPF) 3
The low frequency component of the output of the synchronous rectification circuit 35a is extracted by 6a to obtain the sine waveform (a). Similarly, the difference between the induced voltages generated in the coil 32b and the coil 32d is detected by the subtractor 37b and processed by the synchronous rectifier circuit 35b and the LPF 36b to obtain a sine waveform (b). Since the obtained two sine waveforms change according to the relative position between the mover 2 and the scale 8, it is possible to detect the position of the mover 2 on the scale 8 by monitoring this. Become.

[0005]

However, in the position detecting device in the linear pulse motor described above, it is necessary to provide the coils 32a to 32d different from the drive coil of the mover 2, which limits the miniaturization of the motor. is there. Also,
It has a drawback that a detection circuit for generating a high frequency and detecting an induced voltage is complicated.

It is an object of the present invention to provide a linear pulse motor capable of detecting the position with a simple structure without increasing the size of the motor.

[0007]

A linear pulse motor according to the present invention is a linear pulse motor having a mover having magnetic pole teeth and a stator provided facing the mover and having a coil and magnetic pole teeth. , A detecting means comprising a light source for irradiating the side surface of either the stator or the mover with light to the tooth surface of the other magnetic pole and a light receiving element for receiving the light reflected by the tooth surface of the magnetic pole. Characterize.

[0008]

In the linear pulse motor having the above structure, the light emitted from the light source is reflected by the magnetic pole tooth surface formed on the mover or the stator. The reflected light is detected by the light receiving element and converted into an electric signal. The converted electrical signal is
The signal changes according to the relative position between the mover and the stator.

[0009]

1 is a perspective view showing the construction of an embodiment of a linear pulse motor of the present invention, and FIG. 2 is a side view of FIG.

In a flat plate linear pulse motor (hereinafter referred to as a motor) 1, a mover 3 is movable in an arrow direction via a ball 14 and a roller 15 which a retainer 5 supports on a stator 2. The stator 2 includes a yoke 11, a coil 12, and magnetic pole teeth 13, and is fixed to the reinforcing plate 4. A V-shaped groove 19 is formed on the upper surface of the reinforcing plate 4, and two balls 14 supported by the retainer 5 are fitted therein. By inserting the ball 14 into the V-shaped groove 19, the moving direction of the retainer 5 with respect to the reinforcing plate 4 is defined. Further, a V-shaped groove 18 is also formed on the lower surface of the mover 3, and the ball 14 of the retainer 5 fits into this V-shaped groove 18. By this fitting, the mover 3 with respect to the retainer 5
The moving direction of is specified.

From the above, the mover 3 has the V of the reinforcing plate 4.
It moves in a direction parallel to the groove 19. Reinforcement plate 4
A mounting plate 6 is screwed onto the mounting plate 6, and is mounted in a device such as a floppy disk drive via the mounting plate 6.

The position detector 20 is attached outside the moving direction of the mover 3 of the motor 1 and detects irregularities of the magnetic pole teeth 8 formed on the mover 3 by etching or the like.

FIG. 3 is a sectional view showing the construction of an embodiment of the position detector 20 of FIG. The magnetic pole teeth 8 formed on the mover 3 have peaks 29 and valleys 30 alternately arranged at a constant pitch P.
Are arranged in. The position detector 20 is composed of a light projecting portion 22 formed of an LED or a laser light source, and a light receiving portion 23 formed of a photodiode, a phototransistor, or the like. The pitch between the position detectors 20 is the pitch P of the magnetic pole teeth 8.
Pitch offset by 1/4 × P, nP +
They are arranged so as to be ¼ × P. Since the magnetic pole teeth 8 are processed by, for example, etching, the valley portion 30 has an arc shape due to erosion. Therefore, the light projecting portion 22 to the valley portion 30
The light radiated on is scattered and the reflected light does not return to the light receiving unit 23. On the other hand, the light applied to the mountain portion 29 is reflected and detected by the light receiving portion 23. In this way, it is possible to detect the unevenness of the magnetic pole teeth 8. Further, since the pitch of the position detector 20 is offset by 1/4, it is possible to take out detection signals with a 90 ° phase shift.

Although the position detector 20 detects the magnetic pole teeth 8 of the mover 3, it may be attached to the side of the mover 8 to detect the magnetic pole teeth 13 of the stator 2. ..

FIG. 4 is a perspective view showing the configuration of another embodiment of the linear pulse motor of the present invention. Position detector 20
Is composed of a light projecting section 24 such as an LED, a light receiving section 25 such as a phototransistor, a partially transmissive plate 21, and magnetic pole teeth 8. In the partially transmissive plate 21, non-transmissive regions 27 and transmissive regions 28 extending in a direction orthogonal to the displacement direction B are alternately arranged at a constant pitch P. However, the lengths of the non-transmissive region 27 and the transmissive region 28 in the displacement direction B do not necessarily have to be equal.

The non-transmissive area 27 is an area having a low light transmittance (preferably opaque), and the transmissive area 28 is an area having a high light transmittance (preferably transparent). For example, the partial transmissive plate 21 is a glass plate. It can be manufactured by printing a black paint on a transparent plate such as a transparent plastic substrate or the like at a constant pitch to form non-transmissive regions 27, and leaving the transparent plate as a transparent region 28.

On the surface of the magnetic pole teeth 8, valleys 30 and peaks 29 extending in a direction orthogonal to the displacement direction B of the partial transmission plate 21 are alternately arranged at the same pitch P as the synchronization pattern of the partial transmission plate 21. It is arranged. However, the lengths of the valley portion 30 and the mountain portion 29 in the displacement direction B do not necessarily have to be the same. The valley portion 30 has a low reflectance as in the description of FIG. 3, while the crest portion 29 has a high reflectance.

The partial transmission plate 21 is arranged parallel to the surface of the magnetic pole teeth 8, and the distance b between the partial transmission plate 21 and the magnetic pole teeth 8 is larger than the pattern pitch P of the partial transmission plate 21 and the magnetic pole teeth 8. It is arranged to be small.

FIG. 5 is a perspective view showing the configuration of still another embodiment of the linear pulse motor of the present invention, in which a plurality of pairs of light projecting portions 24 and light receiving portions 25 are provided and the partial transmission plate 21 is sandwiched. Are arranged side by side on the side opposite to the magnetic pole teeth 8 and the distance a (see FIG. 6) between the light projecting portion 24, the light receiving portion 25 and the partial transmission plate 21 is the distance b between the partial transmission plate 21 and the magnetic pole teeth 8.
It is arranged to be sufficiently larger than.

As shown in FIG. 5, the light projecting section 24 and the light receiving section 2
By using two pairs of 5, it is possible to take out signals with a 90 ° phase shift. Here, the magnetic pole tooth 8 of the mover 3 is 1
The two sets of light emitting / receiving sections of the position detector 20 are arranged in parallel with the magnetic pole teeth 8 and are displaced by / 4 × P. The magnetic pole teeth 8
If the pitches of the two are not out of phase, the position detector 2
The pattern of the partial transmission plate 21 at 0 is shifted by ¼ × P.

The light emitting section 24 and the light receiving section 25 of the position detector 20.
Can be realized at low cost because a photomicrosensor can be used.

FIG. 6 is a circuit diagram showing an embodiment of the signal processing circuit. The light detected by the light receiving section 25 is amplified by the signal processing circuit 31 and processed by the comparator 26 as a rectangular wave signal. It

[0023]

As described above, according to the linear pulse motor of the present invention, since the magnetic pole teeth are used as a scale, the number of components is small, and the motor is small in size and simple in structure without changing the structure. The position detector can be attached externally.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of a linear pulse motor of the present invention.

FIG. 2 is a side view of the linear pulse motor of FIG.

3 is a side view showing the configuration of an embodiment of the position detector 20 of FIG.

FIG. 4 is a perspective view showing the configuration of a second embodiment of the linear pulse motor of the present invention.

FIG. 5 is a perspective view showing the configuration of a third embodiment of the linear pulse motor of the present invention.

6 is a circuit diagram showing an embodiment of a position detection circuit by the position detector 20 of FIGS. 4 and 5. FIG.

FIG. 7 is a perspective view showing a configuration of an example of a conventional linear pulse motor.

FIG. 8 is a circuit diagram showing a configuration of an example of a conventional position detection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flat plate linear pulse motor 2 Stator 3 Mover 8 Magnetic pole tooth 13 Magnetic pole tooth 20 Position detector 21 Partial transmission plate 22, 24 Light emitting part 23, 25 Light receiving part

Claims (1)

Claim: What is claimed is: 1. A linear pulse motor having a mover having magnetic pole teeth, and a stator provided facing the mover and having coils and magnetic pole teeth. It is characterized in that the movable element is provided with a detection means including a light source for irradiating the other magnetic pole tooth surface with light and a light receiving element for receiving the light reflected by the magnetic pole tooth surface. Linear pulse motor.