JPS624944B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a linear actuator that drives mechanical elements, and in particular, the present invention relates to a linear actuator that drives mechanical elements, and in particular, to a linear actuator that drives mechanical elements, and in particular, the linear actuator that drives mechanical elements, such as needle selection control of knitting machines, needle amplitude control of sewing machines, and cloth feed control of sewing machines. The present invention relates to a linear actuator used for mechanical element drive control that requires relatively small force but requires high positioning accuracy. (Prior Art) A conventional linear actuator is equipped with a feedback potentiometer for accurately positioning a mechanical element driven by the linear actuator (for example, Japanese Patent Laid-Open No. 53-27851). The position designation signal is compared with the feedback signal from the potentiometer to accurately drive the mechanical element to the position represented by the position designation signal. (Problems to be solved by the invention) One of the problems of such a linear actuator
First, since the actuator itself must also drive the slider of the potentiometer, the actuation force imposed on the actuator must be large. In particular, a rotary type potentiometer with a rotary axis is generally used, but the movement of the mover of the actuator (linear motion)
In driving the potentiometer by converting the rotation into rotational motion through a motion transmission means such as a combination of a pinion and a rack, a relatively large force is applied to drive the motion transmission means. One of the other problems is that such actuators are coupled to mechanical elements that are driven repeatedly quickly, and the durability of the potentiometer, especially the durability of the film resistor, is low compared to the durability of the entire mechanical device. It is. A first object of the present invention is to provide a linear actuator that consumes less force, a second object is to provide a linear actuator that is highly durable, and a third object is to provide a linear actuator that consumes less force. The object of the present invention is to provide a linear actuator that allows positioning to be performed in steps rather than continuously. [Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the linear actuator of the present invention includes a magnetic core having a predetermined length,
A bobbin through which the magnetic core extends in the longitudinal direction and is movable in the longitudinal direction relative to the magnetic core; an electric coil wound around the bobbin; and a bobbin that extends in the longitudinal direction of the magnetic core. a permanent magnet disposed parallel to the magnetic core along the length direction, polarized in a direction perpendicular to the length direction, and having a surface facing the magnetic core having the same polarity along the length direction; A magnetic yoke coupled to a surface of the permanent magnet opposite to the surface facing the magnetic core, and a magnetic yoke coupled to both lengthwise ends of the magnetic core, instructing selection of a light pattern corresponding to a position instruction signal. an optical pattern selection means, an optical pattern forming device that generates a light pattern in which brightness and darkness of light is distributed in the length direction of the magnetic core and that corresponds to the instruction, a photoelectric conversion means that detects the light of the optical pattern, and an energization control circuit that energizes the electric coil in the forward direction when the photoelectric conversion means is detecting darkness and in the reverse direction when the photoelectric conversion means is detecting light; One is fixed to the bobbin, and the other is fixed. (Function) In this linear actuator, the permanent magnet is
The magnetic core is arranged parallel to the magnetic core along the length direction, is polarized in a direction perpendicular to the length direction, and has a surface facing the magnetic core along the length direction. and have the same polarity, and the magnetic yoke is connected to the surface of the permanent magnet opposite to the surface facing the magnetic core, and to both longitudinal ends of the magnetic core.
Magnetic flux flows through the permanent magnet-magnetic core-magnetic yoke-permanent magnet loop, and a parallel magnetic field is formed between the magnetic core and the permanent magnet. A portion of the electric coil wound around the bobbin is located between the permanent magnet and the magnetic core and is perpendicular to this parallel magnetic field, and the electric coil is wound around the magnetic core through the bobbin and is opposite to the parallel magnetic field. Therefore, when the electric coil is energized in the positive direction, a force in the length direction of the magnetic core acts on the electric coil according to Fleming's left hand rule.
When the magnetic core is fixed, the electric coil moves along the length of the magnetic core toward one end thereof.
When the electric coil is energized in the opposite direction, the electric coil moves to the other end. The optical pattern selection means instructs selection of an optical pattern corresponding to the position instruction signal, and the optical pattern forming device generates an optical pattern corresponding to this instruction, in which brightness and darkness of light are distributed in the length direction of the magnetic core, A photoelectric conversion means detects the light of this light pattern, and
One of the optical pattern forming device and the photoelectric conversion means is fixed to the bobbin, and the bobbin and the electric coil are integrated, so when the electric coil is energized and moves as described above, the optical pattern crosses the photoelectric conversion means, A photoelectric conversion means detects brightness and darkness of the light pattern. Therefore, the energization control circuit energizes the electric coil in the forward direction when the photoelectric conversion means is detecting darkness, and energizes it in the reverse direction when the photoelectric conversion means is detecting light.
While the photoelectric conversion means detects brightness, the electric coil is energized in the opposite direction to move in the opposite direction, and the photoelectric conversion means moves in the opposite direction relative to the optical pattern forming device. When the photoelectric conversion means detects darkness in the light pattern due to this movement, the electric coil is energized in the forward direction and the photoelectric conversion means moves in the forward direction.
Due to this movement, the photoelectric conversion means detects the brightness of the light pattern. In this way, the photoelectric conversion means vibrates in positive and negative directions relative to the light pattern, centering on the boundary point between dark and light in the light pattern. ) or the inertia of the magnetic core (if it is movable) is relatively small, and the photoelectric conversion means and the energization control circuit have relatively high responsiveness, it will remain substantially stationary at the boundary point. Become. If this is not the case, slight vibrations will occur from side to side around the boundary point. In any case, the photoelectric conversion means is determined at the boundary point between bright and dark in the light pattern. That is, the bobbin (or magnetic core) to which the photoelectric conversion means is coupled is positioned at the bright/dark boundary point of the optical pattern with respect to the magnetic core (or bobbin) to which the optical pattern forming device is coupled. When the light pattern selection means changes the position instruction signal, the light pattern changes accordingly, and the photoelectric conversion means moves to the bright/dark boundary point of this light pattern. In this way, since position indication and position detection are performed optically, there is virtually no need for a mechanical power transmission system, driving force, or mechanical contact structure for obtaining a position feedback signal, and the linear system of the present invention The actuator consumes less force and is highly durable. Since light and dark detection of the light pattern is binary, positioning is stepwise rather than continuous. Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings. (Example 1) Fig. 1a shows a first embodiment of the present invention, and Fig. 1b shows a first embodiment of the present invention.
The figure shows the drive circuit. In FIG. 1a, an electric coil 2, which is an actuator, is wound around a bobbin 1, and this bobbin 1 has a magnetic core 3.
is movably guided along the axial direction. Both ends of the magnetic core 3 are fixed to a magnetic yoke 4. The yoke 3 has two parallel to the magnetic core 3.
Magnetism magnets 5 ₁ and 5 ₂ are fixed.
As shown in FIG. 1a, these permanent magnets 5 ₁ and 5 ₂ are polarized in a direction perpendicular to the longitudinal axis of the magnetic core 3, and have the same polarity in the direction along the longitudinal axis. . A sensor housing 8 is fixed to the bobbin 1, which houses a phototransistor 6 (FIG. 1b) which is a photo sensor, and an energization control circuit 7 that switches the direction of energization of the coil 2 based on the light detected by the phototransistor 6. There is. A circuit board 9 is fixed to the yoke 4, and a light emitting element array 10 in which a plurality of light emitting diodes D1 to D12 (FIG. 1b) are arranged parallel to the longitudinal axis of the magnetic core 3 is mounted on the circuit board 9. , an energizing circuit 11 that energizes these light emitting diodes D1 to D12 to emit light according to an input signal.
A driver unit 13 in which a decoder 12 and a decoder 12 are integrated is fixedly attached. The sensor housing 8 has a light transmission window facing the light emitting element array 10, and the phototransistor 6 is arranged inside this light transmission window. Since the surfaces of the permanent magnets 5 ₁ , 5 ₂ facing the core 3 are north poles, magnetic flux flows from the magnets 5 ₁ , 5 ₂ to the core 3 , and this flows through the core 3 and the yoke 4 to the magnets 5 ₁ , 5 ₂ . Since it goes towards the S pole, the magnet 5 ₁ ,
A parallel magnetic field is formed between the core ₃ and the coil 2 wound around the bobbin ₁ .
and between the magnet 52 and the core 3, and between the magnet ₅₂ and the core 3, which are orthogonal to this parallel magnetic field. In the configuration shown in FIG. 1a, when the coil 2 is energized in the forward direction, a current flows upwardly from below in the first portion of the coil 2 between the magnetic core 3 and the magnet ₅₁ . On the other hand, since there is a magnetic field directed from the magnet ₅₁ toward the magnetic core 3, a force directed toward the left acts on the first portion according to Fleming's left-hand rule. At this time, a current flows downward from above in the second portion of the coil 2 between the magnetic core 3 and the magnet ₅₂ , and on the other hand, a magnetic field exists from the magnet ₅₂ toward the magnetic core 3. According to Fleming's left hand rule, a force directed to the left also acts on the second portion. Therefore, by energizing the coil 2 in the positive direction, the bobbin 1 moves to the left. When coil 2 is energized in the opposite direction, bobbin 1
moves to the right. See Figure 1b. Please also refer to FIG. 1a. The energization control circuit 7 includes transistors Tr ₁ and Tr ₂ for forward energization and transistors Tr ₃ and Tr ₄ for reverse energization.
(Fig. 1a)
In response to non-light reception, coil 2 is set as shown in Table 1 below.
The current direction is determined.

〔Effect of the invention〕

As explained above, the linear actuator of the present invention performs position indication and position detection optically, so it requires a mechanical power transmission system, driving force, and mechanical contact to obtain a position feedback signal. It requires virtually no structure, consumes little force and is highly durable. Since light and dark detection of the light pattern is binary, positioning is stepwise rather than continuous.

[Brief explanation of the drawing]

FIG. 1a is a perspective view showing the external appearance of a first embodiment of the present invention, and FIG. 1b is a block diagram showing its energizing circuit. FIG. 2a is a plan view of the knitting machine equipped with the linear actuator shown in FIG. 1a, and FIG. 2b is a sectional view taken along line B-B of the knitting machine. FIG. 3a is a perspective view showing the external appearance of a second embodiment of the present invention, FIG. 3b is a sectional view taken along the line B--B, and FIG. 3c is a block diagram showing the energizing circuit. FIG. 4a is a perspective view showing the external appearance of a third embodiment of the present invention, FIG. 4b is a sectional view taken along the line B--B, and FIG. 4c is a block diagram showing the energizing circuit. 1: bobbin, 2: coil, 3: magnetic core,
4: Yoke, 5 ₁ , 5 ₂ : Permanent magnet, 6, 6 ₁ ~
6 ₅ : Phototransistor (photoelectric conversion means),
7: Energization control circuit, 8: Housing, 9: Circuit board, 1
0: Light emitting element array (D1-D12, D11: optical pattern forming device), D1-D12, L1-L
5, 36: Light emitting diode (light emitting element), 11:
energizing circuit (light emitting energizing circuit), 12: decoder (light pattern selection means), 13: driver unit,
14: Carriage, 15: Needle bed, 16: Rail,
17, 26, 35: Pulse motor, 18: Gearbox, 19: Pinion, 20: Rack, 21:
Knitting needle, 22 ₁ , 22 ₂ : Guide member, 23 : Head, 24 : Stay, 25 : Thread opening, 27 ₁ , 27
₂ , 28: Photo sensor (29, L1 to L5: optical pattern forming device) (31 ₀ to 31 ₅ , 32: selective connection circuit), 29: Light shielding plate, 30 ₁ , 30 ₂ :
Support rod, 31 ₀ to 31 ₅ : Normally open relay, 33: Decoder (light pattern selection means), 34: Drum,
35: pulse motor, 35A: motor driver (34-38: optical pattern forming device).

Claims (1)

[Scope of Claims] 1. A magnetic core having a predetermined length; a bobbin that is movable in the longitudinal direction relative to the magnetic core, through which the magnetic core penetrates in the longitudinal direction; an electric coil wound around the bobbin, arranged parallel to the magnetic core along the length direction of the magnetic core, polarized in a direction perpendicular to the length direction, and facing the magnetic core; a permanent magnet whose faces are of the same polarity along the length direction; a magnetic yoke; a light pattern selection means for instructing selection of a light pattern corresponding to a position instruction signal; a light pattern forming device for generating a light pattern in accordance with the instruction by distributing brightness and darkness of light in the length direction of the magnetic core; a device, a photoelectric conversion means for detecting the light of the light pattern, and an energization control that energizes the electric coil in the forward direction when the photoelectric conversion means detects darkness and in the reverse direction when the photoelectric conversion means detects light. A linear actuator comprising a circuit, wherein one of the optical pattern forming device and the photoelectric conversion means is fixed to the bobbin, and the other is fixed. 2. The optical pattern forming device includes a plurality of light emitting elements arranged and fixed along the length direction of the magnetic core and one or more of the light emitting elements turned on in response to a signal from the optical pattern selection means. Claim 1, wherein the photoelectric conversion means is a photo sensor fixed to the bobbin.
Linear actuator described in section. 3. The optical pattern forming device includes a light-shielding plate fixed to a bobbin, which has light-transmitting portions distributed in a stepped manner along the length direction of a magnetic core, and a light-shielding plate fixed to a bobbin, and the light-transmitting portions extending in the stepped height direction. a light-emitting element that generates light, and a light-emitting energizing circuit that energizes the light-emitting element to emit light, and the photoelectric conversion means faces the light-emitting element through the light shielding plate and is fixed in the height direction of the stepped shape. 2. The linear actuator according to claim 1, comprising a plurality of arrayed photo sensors and a selective connection circuit for selectively connecting one photo sensor to the energization control circuit in response to an instruction from the light pattern selection means. 4. The optical pattern forming device includes a drum having a light reflecting surface and a light absorbing surface with spiral boundaries on the circumferential surface and arranged parallel to the magnetic core in the length direction of the magnetic core, and rotating this drum. It consists of a driving motor and a motor energizing circuit that energizes the motor in forward and reverse directions and stops it in response to instructions from the optical pattern selection means, and the photoelectric conversion means is a photo sensor fixed to the bobbin and facing the circumferential surface of the drum. A linear actuator according to claim 1.