JPH06224030A - Solenoid device - Google Patents

Abstract

PURPOSE:To precisely detect the rate and position of a driving coil by a method wherein a search coil is wound up not to be affected by the flux of driving coil. CONSTITUTION:The solenoid device is provided with a bottomed cylindrical yoke 18, a magnet 19 held by this yoke 18 and a columnar pole piece 21 fixed to the magnet 19 making a specific gap 20 between the yoke 18. A bottomed cylindrical bobbin 13 is arranged to be loosely inserted downward into the pole piece 21 while a driving coil 22 is fixed to the aperture lower end edge of the bobbin 13 to be suspended. Furthermore, a search coil 23 is wound around concentrically with the driving coil 22. This search coil 23 is wound around the bobbin 13 as if passing through the gap of the driving coil 22 while inversing the winding up direction bordering on the rewinding part 23c on almost central position in the long direction of the bobbin 13. Through these procedures, the shifting rate and position of the search coil 23 can be precisely detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid device used, for example, for driving a pen holder (pen head) of an automatic drawing machine (plotter), and more particularly to a solenoid device for controlling the up / down operation of the pen head.

[0002]

2. Description of the Related Art In order to drive a pen head of a plotter, it is required that the up / down operation of the pen head is fast and that slow landing is performed when the pen head is down.

In a conventional pen head driving device,
It uses a solenoid. This solenoid has a coil for magnetizing a magnetic path structure including a movable iron core. And by energizing this coil,
Alternatively, by stopping the energization, the movable iron core is moved up and down to drive the pen head connected to the movable iron core.

Therefore, when the speed control or the position control of the vertical movement of the pen head is performed in this pen head drive device, the speed sensor or the position sensor must be attached to the pen head. The vertical speed or position of the pen head is controlled based on the values detected by these sensors.

As a result, these sensors require mechanical space in the drive and add to their weight. That is, it goes against the requirement of the plotter, which is faster and lighter and smaller. In addition, in terms of cost,
These sensors are expensive. Further, the processing cost of the pen head also becomes high.

[0006] Therefore, as a solenoid device for solving such a problem, the applicant of the present invention has filed Japanese Patent Application No. 3-425.
The solenoid device shown in No. 04 was devised.
As shown in FIG. 13, this solenoid device has a bottomed cylindrical yoke 108, a magnet 109 held by the yoke 108, and a yoke 108 fixed to the magnet 109.
And a columnar pole piece 201 that forms a predetermined gap 200 between and. The bobbin 103 having a bottomed cylindrical body is arranged so as to be loosely fitted to the pole piece 201 from the upper side. There is. At the same time, a search coil 203 is wound concentrically with the drive coil 202. The drive coil 202 and the search coil 203 are provided so that the gap 200 can be moved up and down. The search coil 203 coaxially wound with the drive coil 202 has a smaller wire diameter than that of the drive coil 202 and has the same pitch.

A drive circuit is connected to the drive coil 202, and the drive coil 202 moves up and down by the current supplied from the drive circuit. When the search coil 203 along with the drive coil 202 crosses the magnetic flux in the gap 200, the search coil 2
An induced electromotive force is generated in 03. Based on this induced electromotive force,
The speed of the search coil 203 is calculated, and the position of the search coil 203 is calculated by integrating this speed. Based on the speed and position of the search coil 203,
The amount of current flowing through the drive coil 202 is controlled.
A predetermined magnetic flux is generated in the drive coil 202 according to this amount of current, and the drive coil 202 moves due to the force acting between this magnetic flux and the magnetic flux in the gap 200.
That is, the moving speed of the pen head driven by the drive coil 202 is controlled based on the speed and position of the search coil 203.

[0008]

However, in such a conventional solenoid, the search coil 203 is used.
Is wound on the concentric circle of the drive coil 202,
The search coil 203 is affected by the magnetic flux emitted from the drive coil 202. That is, Search Coril 2
03 interlinks with the magnetic flux in the gap 200, and also interlinks with the magnetic flux from the drive coil 202. Therefore, when the magnetic flux generated by the drive coil 202 changes, the search coil 203
An induced electromotive force is generated due to this change in magnetic flux. Therefore, when the moving speed and the position of the search coil 203 are calculated based on the induced electromotive force generated in the search coil 203, an error occurs in the calculated moving speed of the search coil 203 and the value of the position. . Therefore, it becomes difficult to accurately detect the moving speed and the position of the drive coil 202, which makes it difficult to accurately control the position of the pen head.

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to accurately detect the speed and position of a drive coil in a solenoid device by winding a search coil so as not to be affected by the magnetic flux of the drive coil.

[0010]

According to a first aspect of the present invention, there is provided a solenoid device including a drive coil movably arranged in a magnetic flux, and a search coil integrally held with the drive coil. The search coil has a first coil portion wound in a predetermined direction and a second coil portion wound in a direction opposite to the direction, and the first coil portion is distributed in the magnetic flux. It is a solenoid device characterized by being installed.

According to a second aspect of the present invention, there is provided a control circuit for supplying a predetermined current to the drive coil in accordance with the voltage output from the search coil, and the drive coil is connected to a pen holder of a plotter. It is the described solenoid device.

[0012]

In the solenoid device according to the first aspect of the present invention, when a predetermined current is applied to the drive coil, the search coil moves together with the drive coil. Then, since the first coil portion of the search coil crosses the magnetic flux, an induced electromotive force proportional to the moving speed is generated in the first coil portion. On the other hand, even if the magnetic flux generated by the drive coil changes, the induced electromotive forces generated in the first coil portion and the second coil portion cancel each other out. Therefore, only the induced electromotive force generated by the first coil portion crossing the magnetic flux is generated at both ends of the search coil. Therefore, an induced electromotive force corresponding to the speed of the search coil is generated in the search coil without being affected by the magnetic flux of the drive coil.

In the solenoid device according to the second aspect of the present invention, the control circuit can accurately detect the speed and position of the search coil based on the induced electromotive force corresponding to the moving speed of the search coil. Therefore, the control circuit, based on the induced electromotive force output from the search coil,
By supplying a predetermined current to the drive coil, the position and speed of the pen holder of the plotter can be controlled accurately.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a solenoid device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a solenoid device according to a first embodiment of the present invention. FIG. 2 shows a plotter using this solenoid device.

As shown in these figures, the solenoid 11
Is for raising and lowering the pen head 12. The pen head 12 is suspended from a bobbin 13, which is a movable part of the solenoid 11, via a support mechanism (carriage) 14, and is arranged so as to be able to contact the paper surface 15. The support mechanism 14 includes a fixed base 16 for fixing the solenoid 11 and a stroke adjusting screw 17 for the pen head 12.
And a return spring 1a8.

As shown in FIG. 1, the solenoid 11 has a bottomed cylindrical yoke 18, a magnet 19 held by the yoke 18, and a yoke 18 fixed to the magnet 19.
And a columnar pole piece 21 that forms a predetermined gap 20 between the pole piece 21 and the pole piece 21. Bobbin 13 with a bottomed cylinder
The bobbin 13 is loosely fitted to the pole piece 21 from the upper side, and a drive coil 22 wound in a cylindrical shape is fixed and hung on the lower end edge of the opening of the bobbin 13. At the same time, the search coil 23 is wound concentrically with the drive coil 22. As will be described later, the search coil 23 is arranged in the gap between the drive coils 22. The drive coil 22 and the search coil 23 are provided so as to be vertically movable in the gap 20. A drive circuit is connected to the drive coil 22. This drive circuit controls the voltage applied to the drive coil 22.

FIG. 3 shows the drive coil 22 and the search coil 2.
It is sectional drawing of 3 grade | etc.,. The drive coil 22 is wound around the bobbin 13 in the same rotation direction. That is, as shown in FIG. 9, the drive coil 22 is wound in the same rotation direction from the winding start position A of the bobbin 13 to the winding end position B. Therefore, when a direct current is passed through the drive coil 22, a magnetic field is generated in the bobbin 13.

The diameter of the search coil 203 is smaller than that of the drive coil 22. The search coil 23 is fitted into the gap of the drive coil 22.
It is wound around the bobbin 13. Then, at a substantially central position in the longitudinal direction of the bobbin 13, the winding direction of the search coil is reversed with the winding portion 23C as a boundary. That is, as shown in FIG. 4, the search coil 23 includes a search coil upper half portion 23A (first coil portion) and a search coil lower half portion 23B having a winding direction opposite to that of the search coil upper half portion 23A.
(Second coil portion), and is configured. The number of turns of each of the search coil upper half portion 23A and the search coil 23B is the same. The upper half portion 23A of the search coil is located between the pole piece 21 and the yoke 18. Therefore, when the bobbin 13 moves up and down, the upper half portion 23A of the search coil mainly interlinks with the magnetic flux in the gap 20.

The induced electromotive force flowing in the search coil 23 thus constructed will be described with reference to FIGS. 5 and 6. 5 and 6 are simplified views of the upper half portion 23A of the search coil and the lower half portion 23B of the search coil of the search coil 23. In FIG. 5, the magnetic flux φm traveling from the pole piece 21 to the yoke 18 passes only through the search coil upper half portion 23A as described above. When the entire search coil 23 moves in the moving direction x, only the upper half portion 23A of the search coil crosses the magnetic flux φm. Therefore, an induced electromotive force is generated only in the upper half portion 23A of the search coil, and a current flows in the direction of the arrow in FIG. Search coil 2
A voltage Vm =-(dφm / dt) is generated between both terminals of No. 3. That is, a voltage Vm proportional to the moving speed is generated between both terminals of the search coil 23.

On the other hand, the magnetic flux φn generated by the drive coil 22 is
As shown in FIG. 6, it passes through the respective loops of the search coil upper half portion 23A and the search coil lower half portion 23B. When the current flowing through the drive coil 22 changes, the magnetic flux φn also changes. Therefore, in each of the search coil upper half portion 23A and the search coil lower half portion 23B,
Induced electromotive force is generated. However, since the winding directions of the search coil upper half portion 23A and the search coil lower half portion 23B are opposite to each other, currents that cancel each other flow. Therefore, no voltage due to the magnetic flux φn is generated between both terminals of the search coil 23. That is, the search coil 23 is not affected by the magnetic flux generated by the drive coil 22.

The search coil 23 may be wound as shown in FIG. Even in this case, the induced electromotive force due to the interlinking of the magnetic flux φn generated by the drive coil 22 can be canceled.

FIG. 9 is a diagram showing a control circuit of a plotter using this solenoid device. When the search coil 23 moves together with the bobbin 13, a voltage Vm proportional to the moving speed is generated at both terminals of the search coil 23. This voltage Vm is the OP amplifier 8 that functions as a voltage follower.
1 is input to the A / D converter 83.

Further, the voltage Vm is input to an integrating circuit composed of an OP amplifier 82, a capacitor 86 and the like. From the OP amplifier 82, the voltage Vm obtained by integrating the voltage Vm
m'is output. Since the distance is obtained by integrating the speed with time as a variable, the voltage Vm obtained by integrating the voltage Vm is obtained.
m ′ represents the position of the search coil 23. The FET 87 is turned on by a signal output from the CPU 84 when the search coil 23 reaches a predetermined reference position (for example, the position of the search coil 23 when the Benhead is sufficiently separated from the paper). The voltage Vm ′ represents the position of the search coil 23 with respect to the reference position. This voltage Vm ′ is input to the A / D converter 83.

The voltage V input to the A / D converter 83
m and voltage Vm 'are converted to digital data and then CP
Input to U84. The CPU 84 calculates the speed and position of the search coil 23 based on the voltage Vm and the voltage Vm ′ represented by digital data. The speed and position of the drive coil 22 are controlled based on the calculated speed and position. That is, the CPU 84 outputs a predetermined digital signal to the drive circuit 85 based on the calculated speed and position.

The drive circuit 85 has power supplies having different voltages, and a switching circuit interposed between these power supplies and the drive coil 22. The drive circuit 85 applies a predetermined voltage to the drive coil 22 by turning on / off the switching circuit according to the applied digital signal. Then, a predetermined amount of current flows through the drive coil 22, and a magnetic flux φn is generated by the drive coil 22. The magnetic flux φn and the magnetic flux φm between the gaps 20 cause the drive coil 22 to move in either of the upper and lower directions. By moving the drive coil 22,
The search coil 22 traverses the magnetic flux φm and crosses a predetermined voltage Vm.
Is generated. The search coil 22 accurately generates the voltage Vm according to the moving speed without being affected by the drive coil 22.

Therefore, the CPU 84 uses the search coil 2
Since the position of 2 can be accurately obtained, the position of the pen head can be accurately controlled. Therefore, when the pen head is lowered onto the paper, it is possible to prevent a problem that the pen head collides with the paper at an undesired speed.

Next, a solenoid device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a sectional view of the solenoid device according to the present embodiment.
FIG. 11 is a diagram showing the search coil 223 in a simplified manner. In this figure, the yoke 108 has a "U" shape, and a gap 300 is formed between both end portions thereof. A predetermined magnetic flux φm is generated in this gap 300. The drive coil 222 and the search coil 223 have a donut shape and are configured to be movable in the arrow direction in the figure. As shown in FIG. 11, the search coil 223 has an outer coil (first coil portion) and an inner coil second coil portion). The search coil 223 is arranged so that the magnetic flux φm passes through the upper part of the outer coil. The drive coil 222 is wound in the same rotation direction from the winding start position A to the winding end position B. The magnetic flux φn generated by the drive coil 222 passes through the central through hole of the drive coil 222.

The diameter of the search coil 223 is the drive coil 22.
The diameter of the search coil 223 is smaller than the diameter of 2, and the search coil 223 is arranged in the gap between the drive coils 222. Search coil 22
As shown in FIG. 11, 3 is wound such that the winding directions of the outer coil portion and the inner coil portion are opposite to each other. The magnetic flux φm is the search coil 2
23, and the magnetic flux φn penetrates the central portion of the search coil 223.

In the thus constructed solenoid device, when a predetermined current is passed through the drive coil 222, the drive coil 222 moves in the x direction together with the search coil 223. At this time, only the upper portion of the search coil 223 crosses the magnetic flux φm in the gap 300. Therefore, an induced electromotive force proportional to the speed of the search coil 223 is generated. However, even if the magnetic flux φn generated by the drive coil 222 changes, the magnetic flux φn does not interlink with the search coil 223.
It does not occur in 3.

Therefore, similarly to the solenoid device according to the first embodiment, the moving speed and position of the search coil 223 can be accurately detected without being affected by the magnetic flux φn generated by the drive coil 222. is there. Further, since the search coil 223 is arranged in the gap of the drive coil 222, it is possible to prevent the shape of the entire coil from increasing. The same effect can be obtained by winding the search coil 223 as shown in FIG.

[0032]

As described above, according to the present invention, the moving speed and position of the search coil can be accurately detected without being affected by the magnetic flux of the drive coil in the solenoid device. Therefore, when the present solenoid device is used in a plotter, the speed and position of the pen head can be accurately detected, and the pen head can be lowered onto the paper without damaging it. Also, because the search coil is placed in the gap of the drive coil,
It is possible to prevent the size of the entire solenoid device from increasing.

[Brief description of drawings]

FIG. 1 is a sectional view showing a solenoid according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a plotter using a solenoid according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a drive coil, a search coil, etc. according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a simplified search coil according to the first embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the search coil and the magnetic flux in the gap according to the first embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the search coil and the magnetic flux generated by the drive coil according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a modified search coil according to the first embodiment of the present invention.

FIG. 8 is a control circuit diagram of the solenoid device according to the first embodiment of the present invention.

FIG. 9 is a diagram showing a drive coil according to the first embodiment of the present invention.

FIG. 10 is a sectional view of a solenoid device according to a second embodiment of the present invention.

FIG. 11 is a diagram showing a simplified search coil according to a second embodiment of the present invention.

FIG. 12 is a sectional view of a search coil according to a second embodiment of the present invention.

FIG. 13 is a cross-sectional view of a conventional solenoid device.

[Explanation of symbols]

 12 pen head 13 bobbin 18 yoke 19 magnet 20 gap 21 pole piece 22 drive coil 23 search coil 23A drive coil upper half (first coil portion) 23B drive coil lower half (second coil portion) 222 drive coil 223 search coil

Claims (2)

[Claims] 1. A solenoid device comprising a drive coil movably arranged in a magnetic flux, and a search coil held integrally with the drive coil, wherein the search coil is wound in a predetermined direction. A solenoid device having a first coil portion and a second coil portion wound in a direction opposite to the direction, the first coil portion being disposed in the magnetic flux. 2. The solenoid device according to claim 1, further comprising a control circuit for supplying a predetermined current to the drive coil in accordance with the voltage output from the search coil, wherein the drive coil is connected to a pen holder of a plotter.