JP2007115794A - Flexible printed circuit board, magnetic encoder using the same and servo motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed circuit board which has less limit of shape working, and which is simple in structure and low in cost. <P>SOLUTION: A wiring conductor 110 wired on the insulating base film 100 of a flexible printed circuit board 10 is provided on both surfaces of a base film in a leading-out section 140, and it is provided to the right or the left in an electrode 130 according to either surface of the provided base film 100. The left side of the electrode 130 is bent from the front to the back in a diagram, and the right side thereof is bent from the rear to the front, so as to expose a conductor 110 for wiring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible printed circuit board, for example, a flexible printed circuit board used for an encoder that detects the position and speed of a servo motor, and a magnetic encoder and a servo motor using the flexible printed circuit board.

In a conventional flexible printed circuit board, a wiring conductor of an electrode portion and an insulating base film are bent toward the base film (see, for example, Patent Document 1). In some cases, only the wiring conductor of the electrode portion is exposed and bent (see, for example, Patent Document 2).
FIG. 6 is a cross-sectional view of an electrode portion of a conventional flexible printed board described in Patent Document 1.
In FIG. 6, 130 is an electrode part, and it is bent to the base film 100 side so that the wiring conductor 110 wired on the insulating base film 100 is exposed. The electrode part 130 is soldered to the circuit board. Reference numeral 120 denotes an insulating cover lay for protecting the wiring conductor, and reference numeral 160 denotes an adhesive for fixing the bent portion of the electrode portion 130.
FIG. 7 is a perspective view of a conventional flexible printed circuit described in Patent Document 2.
In FIG. 7, the wiring conductors 110a and 110b wired on the front and back surfaces of the insulating base film protrude from the base film 100 at the electrode part 130, and are bent in the opposite directions by 90 °, respectively. Soldered.
Thus, in the conventional flexible printed circuit board, the wiring conductor is bent or protruded toward the base film at the electrode portion, so that the wiring conductor is exposed and soldered to the circuit board.
JP-A-5-13905 (FIG. 2) Japanese Patent Laying-Open No. 2001-6441 (FIG. 1)

The conventional flexible printed circuit board described in Patent Document 1 has a structure in which the wiring conductor of the electrode portion and the insulating base film are bent to the base film side, and the wiring conductor is exposed when the bending direction is reversed. I can't. Therefore, the wiring of the wiring conductor can be provided only on one side of the insulating base film, and as the number of signals to be wired increases, the width of the lead-out portion becomes wider, the flexibility becomes worse, and the electrical equipment There was a problem of narrowing the degree of freedom in structural design.
In addition, there is a method of wiring conductors on both sides of the base film so that the width of the drawer part is not widened, and preparing a dedicated connector etc. on the circuit board side to connect with the electrode part. However, there is a problem that the structure is complicated and the cost including the circuit board is increased, such as a board that matches the connector to be used.
Furthermore, in the case where only the wiring conductor of the electrode portion is exposed as described in Patent Document 2, since it lacks rigidity, it is necessary to take measures to prevent damage during work. There is also a problem in that the position of the conductor must be shifted on both sides of the base film so as not to overlap in a state seen through, and the width of the lead-out portion becomes wide.
The present invention has been made in view of such problems, has a high degree of freedom in structural design when applied to electrical equipment, and can also ensure the rigidity of the electrode portion, which is simple and inexpensive. It is an object of the present invention to provide a flexible printed circuit board and a magnetic encoder and a servo motor using the flexible printed circuit board.

In order to solve the above problems, the present invention is configured as follows.
The invention according to claim 1 has an insulating base film, a wiring conductor wired on the base film, and an insulating coverlay for protecting the wiring conductor, and is connected to a circuit board. In the flexible printed circuit board provided with the electrode portion where the wiring conductor is exposed and the lead-out portion to the electrode portion, the wiring conductor is determined depending on whether the wiring conductor is wired on the front or back of the base film. It is characterized in that it is distributed to the left and right at the electrode part and bent in the opposite direction.
The invention according to claim 2 is characterized in that, in the lead-out portion, wiring conductors are wired on both surfaces of the base film.
The invention according to claim 3 is characterized in that the wiring conductors wired to the lead-out portion are wired at the same positions on the front and back sides with a pair of signals.
Further, the invention according to claim 4 is characterized in that the wiring conductor wired to the lead-out portion is wired at the same position on the front and back as a pair of a signal and GND.
Further, the invention according to claim 5 is characterized in that the wiring conductors wired to the lead-out portions are all GND on one side.
The invention according to claim 6 is a disk-shaped permanent magnet fixed to a rotating body, a magnetic field detecting element that faces the permanent magnet via a gap and detects a magnetic field generated by the permanent magnet, The magnetic encoder provided with the flexible substrate which mounted the said magnetic field detection element, and the ring-shaped fixing body which fixes the said flexible substrate, The said flexible substrate is any one of Claims 1 thru | or 5. It is a flexible printed circuit board.
According to a seventh aspect of the present invention, a ring-shaped permanent magnet fixed inside the ring-shaped rotating body and a magnetic field generated by the permanent magnet facing the inner side of the permanent magnet via a gap are detected. In the magnetic encoder comprising: a magnetic field detection element; a flexible board on which the magnetic field detection element is mounted; and a cylindrical or columnar fixed body that is disposed inside the permanent magnet and fixes the flexible board. A flexible substrate is the flexible printed circuit board according to any one of claims 1 to 5.
A servo motor according to claim 8 includes the magnetic encoder according to claim 6 or 7, wherein a rotating body of the magnetic encoder is fixed to a rotating portion of a motor including a permanent magnet, and the magnetic encoder The fixed body is fixed to the fixed portion of the motor.

According to the first aspect of the present invention, the wiring conductors of the flexible printed circuit board on which wiring conductors are wired on both sides are distributed to the left and right at the electrode portions and bent in opposite directions, so that a dedicated connector or the like is used. And can be soldered directly. Therefore, it is possible to realize a flexible printed board having a high rigidity of the electrode part, a simple structure, and an inexpensive price.
According to the second aspect of the present invention, if the wiring conductor is wired on both surfaces of the base film in the lead-out portion, the width of the lead-out portion can be reduced, and the flexibility is improved. The degree of freedom in structural design can be increased.
According to a third aspect of the present invention, if the wiring conductors to be wired to the lead-out portion are wired at the same position on the front and back with a pair of signals, they are more resistant to noise and the reliability of the electrical equipment. Can be improved.
According to the invention described in claim 4, if the wiring conductor wired to the lead-out portion is wired in the same position on the front and back as a pair of signal and GND, it becomes strong against noise, and the reliability of the electric equipment Can be improved.
According to the invention described in claim 5, if the wiring conductors to be wired to the lead-out portion are all grounded to GND, the wiring conductor is strong against noise and the reliability of the electrical equipment can be improved. .
According to the invention described in claim 6 or 7, the wiring board is divided into left and right depending on whether the wiring conductor is wired on the front or back side of the base film, and the flexible board is bent in the opposite direction. Since the magnetic encoder is used, a magnetic encoder that has a high rigidity of the electrode portion connected to the circuit board and has a simple structure can be realized.
Further, if the wiring conductor is wired on both sides of the base film, the width of the lead portion can be reduced and the flexibility is improved, so that a small magnetic encoder can be realized.
According to the eighth aspect of the invention, since the servo motor is provided with a small magnetic encoder with a good lead portion bendability, a small servo motor with a high degree of freedom in structural design can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is a structural diagram of a flexible printed circuit board showing a first embodiment of the present invention. 1B and 1C are a cross-sectional view taken along line BB and a cross-sectional view taken along line CC in FIG. 1A, respectively.
In the figure, 10 is a flexible printed circuit board. The flexible printed board 10 includes an insulating base film 100, a wiring conductor 110 wired on the base film 100, and an insulating coverlay 120 that protects the wiring conductor.
The wiring conductor 110 is wired on both sides of the base film in the lead-out portion 140, and is distributed to the left and right depending on which surface of the base film 100 is wired in the electrode portion 130. In FIG. 1A, a dotted line indicates a wiring conductor wired on the back surface of the base film. In this figure, the insulating coverlay 120 is not shown. The wiring conductor 110 wired on the surface of the base film 100 is distributed to the left side of the electrode part 130, and the wiring conductor 110 wired on the back surface of the base film 100 is distributed to the right side of the electrode part 130. Then, the left side of the electrode part 130 is bent from the front surface to the back surface of the figure so that the wiring conductor 110 is exposed, and the right side of the electrode part 130 is bent from the back surface to the front surface of the figure. In addition, a cutout is provided in the center of the electrode part 130 so that it can be bent in the opposite direction on the left and right.
The part where the present invention is different from the prior art is a part in which the wiring conductor is distributed to the left and right at the electrode part depending on which side of the base film is wired and bent in the opposite direction.

Next, a design example of the width of the drawer portion will be described.
In this invention, although the conductor for wiring can be wired on both surfaces of a base film, it compared with the case where it wired on the single side | surface of a base film.
A wiring conductor wired on the insulating base film needs to have a sufficient conductor width and insulation width to ensure stable operation. In FIG. 1A, a conductor width a and an insulation width b are shown. Assuming that the left and right end faces have the same dimensions as the insulation width b, the conductor width a is set to 0.25 mm, the insulation width b is set to 0.3 mm, and the number of poles, that is, the number of signal lines is assumed to be 8 poles. The width h is determined.

When wiring conductors are wired only on one side of the insulating base film,
Drawer width h = (0.25 × 8 + 0.3 × 7) + (0.3 + 0.3) = 4.7 mm
It becomes.
When wiring conductors are wired on both sides of the insulating base film, the number of wirings on each surface may be half of the four poles.
Drawer width h = (0.25 × 4 + 0.3 × 3) + (0.3 + 0.3) = 2.5 mm
It becomes.

  Thus, in the flexible printed circuit board of the present invention, by eliminating the restriction on the bending direction of the electrode part, the wiring conductor can be wired on both surfaces of the insulating base film, and the width of the lead part is reduced. Can do.

  In addition, the wiring conductor of the lead-out portion can be wired on the both sides of the insulating base film at the overlapping position when seen through. Therefore, it is possible to strengthen against noise by overlapping the signal lines to be paired and wiring the wiring on one side to GND.

2A is a development view of a flexible printed circuit board according to the second embodiment of the present invention, FIG. 2B is a top view at the time of assembly, and FIG. 2C is an arrow shown in FIG. It is the side view seen from D. In the figure, the wiring conductor and the coverlay are omitted.
2A, reference numeral 150 denotes a detection unit on which the detection element 170 is mounted. The detection element 170 may be a Hall element or an MR element. In this embodiment, four Hall elements are mounted as detection elements of the magnetic encoder. In the lead-out portion 140, wiring conductors are wired on both sides of the base film.

In FIG. 2B, reference numeral 180 denotes a circuit board to which the flexible printed board 10 is connected.
The detection unit 150 of the flexible printed circuit board 10 is attached in a state of being wound around a disc-shaped magnet (not shown). A magnetic field change of a magnet (not shown) is output as an analog signal by the Hall element 170 and input to the circuit board 180 via the wiring conductor.
At this time, bending stress is applied to the boundary R between the detection unit 150 and the lead-out unit 140 in the flexible printed circuit board 10. This stress increases as the magnet size is smaller, that is, as the winding diameter of the detection unit 150 is smaller, and as the width of the lead-out unit 140 is wider, there is a problem that the flexible printed circuit board 10 is damaged.
In the flexible printed circuit board of the present invention, since the wiring conductor is wired on both sides of the base film, the width of the lead-out portion can be reduced. Therefore, the flexibility is improved, the possibility of breakage is reduced, and the degree of freedom in the structural design of the electric device can be increased.

FIG. 3 is a perspective view of a magnetic encoder showing a third embodiment of the present invention.
In the figure, 210 is a rotating body, 220 is a disk-shaped permanent magnet fixed to the rotating body 210, 230 is a ring-shaped fixed body, and the flexible substrate 10 on which the magnetic field detecting element 171 is mounted is arranged on the inner peripheral side of the ring-shaped. It is fixed along.
In the electrode part 130 of the flexible substrate 10, the wiring conductors are distributed to the left and right depending on whether the wiring conductors are wired on the front or back side of the base film, and are bent in opposite directions. The electrode unit 130 is soldered to a circuit board (not shown). Moreover, in the drawer part 140, the conductor for wiring is wired on both surfaces of the base film.

Next, the operation will be described.
The magnetic field detection element 171 detects a change in the magnetic field generated by the permanent magnet 220 that rotates as the rotating body 210 rotates. The detected signal is sent to a circuit board (not shown) using a wiring conductor and converted into an angle signal.

FIG. 4 is a perspective view of a magnetic encoder showing a fourth embodiment of the present invention.
In the figure, 211 is a ring-shaped rotating body, 221 is a ring-shaped permanent magnet fixed to the inner peripheral side of the rotating body 211, and 231 is a circular fixed body arranged inside the ring-shaped permanent magnet 221 with a gap. The flexible substrate 10 on which the magnetic field detecting element 171 is mounted is fixed along the outer peripheral side. The configuration of the electrode portion 130 and the configuration of the lead portion 140 of the flexible substrate 10 are the same as those in the third embodiment.
Since the operation is the same as that of the third embodiment, the description thereof is omitted.

  As described above, the magnetic encoders according to the third and fourth embodiments use the flexible substrate in which the wiring conductors are distributed to the left and right at the electrode portions connected to the circuit substrate and bent in opposite directions, respectively. Since the electrode portion connected to the wire has high rigidity and it is not necessary to use a dedicated connector or the like, a magnetic encoder having a simple structure and low cost can be realized. Further, since the wiring conductor of the lead-out portion is provided on both surfaces of the base film, it has good flexibility and can be fixed to a small circular fixed body. Therefore, a small magnetic encoder can be realized.

FIG. 5 is a sectional view of a hollow servomotor showing a fifth embodiment of the present invention.
The magnetic encoder shown in Example 4 was applied.
In the figure, 301 is a frame which is a fixed part of the servo motor, 302 is a stator yoke, 303 is an armature winding, 304 is a motor field permanent magnet, and 305 is a rotor yoke. An encoder rotating body 211 has a ring-shaped permanent magnet 221 fixed on the inner peripheral side, and is coupled to a motor rotor including a motor field permanent magnet 304 and a rotor yoke 305. A magnetic encoder fixed body 231 is coupled to the motor frame 301.
The flexible printed circuit board 10 is fixed to the outer peripheral portion of a fixed body 231 fitted into the motor frame 301. The lead portion 140 is bent along the frame 301 and guided to the circuit board 180 fixed to the frame 301. The electrode unit 130 is directly soldered to the circuit board 180.
When the circuit board 180 is arranged outside the motor, a through hole may be formed in the fixed body 231 and the drawer portion 140 may be passed through the through hole.

As described above, in this embodiment, the servo motor has an electrode part that can be soldered directly to the circuit board, and the lead part has good flexibility and a small magnetic encoder, so the structure is simple. A small servo motor that is inexpensive and has a high degree of freedom in structural design can be realized.
Needless to say, the flexible printed circuit board of the present invention can be applied to other than the magnetic encoder.

BRIEF DESCRIPTION OF THE DRAWINGS (a) Structural drawing of flexible printed circuit board which shows 1st Example of this invention, (b) BB sectional drawing, (c) CC sectional drawing. (A) The developed view of the flexible printed circuit board which shows 2nd Example of this invention, (b) The top view of 2nd Example of this invention, (c) The side view of 2nd Example of this invention. It is a perspective view of the magnetic encoder which shows 3rd Example of this invention. It is a perspective view of the magnetic encoder which shows 4th Example of this invention. It is sectional drawing of the hollow servomotor which shows 5th Example of this invention. It is sectional drawing of the electrode part of the conventional flexible printed circuit board. It is a perspective view of the conventional flexible printed circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flexible printed circuit board 100 Base film 110 Wiring conductor 120 Coverlay 130 Electrode part 140 Lead part 150 Detection part 160 Adhesive 170 Detection element 171 Magnetic field detection element 180 Circuit board 210, 211 Rotating body 220, 221 Permanent magnet 230, 231 fixation Body 301 Frame 302 Stator yoke 303 Armature winding 304 Motor field permanent magnet 305 Rotor yoke

Claims (8)

An electrode portion having an insulating base film, a wiring conductor wired on the base film, and an insulating coverlay for protecting the wiring conductor, wherein the wiring conductor connected to the circuit board is exposed And in a flexible printed circuit board with a lead-out part to the electrode part,
A flexible printed circuit board, wherein the wiring conductor is distributed to the left and right at the electrode portion and bent in opposite directions depending on whether the wiring conductor is wired on the front or back side of the base film.   The flexible printed circuit board according to claim 1, wherein a wiring conductor is wired on both sides of the base film in the lead-out portion.   The flexible printed circuit board according to claim 1, wherein the wiring conductors wired to the lead-out portion are wired at the same positions on the front and back sides with a pair of signals.   2. The flexible printed circuit board according to claim 1, wherein the wiring conductors wired to the lead-out part are wired at the same position on the front and back sides as a pair of a signal and GND.   The flexible printed circuit board according to claim 1, wherein the wiring conductors wired to the lead-out portion are all GND on one side. A disk-shaped permanent magnet fixed to a rotating body, a magnetic field detection element that detects a magnetic field generated by the permanent magnet facing the permanent magnet through a gap, and a flexible substrate on which the magnetic field detection element is mounted; In a magnetic encoder provided with a ring-shaped fixing body for fixing the flexible substrate,
The magnetic encoder according to claim 1, wherein the flexible substrate is the flexible printed circuit board according to claim 1. A ring-shaped permanent magnet fixed inside a ring-shaped rotating body, a magnetic field detection element for detecting a magnetic field generated by the permanent magnet facing the inner side of the permanent magnet via a gap, and the magnetic field detection element are mounted. In a magnetic encoder comprising: a flexible substrate, and a cylindrical or columnar fixed body that is disposed inside the permanent magnet and fixes the flexible substrate,
The magnetic encoder according to claim 1, wherein the flexible substrate is the flexible printed circuit board according to claim 1.   A magnetic encoder according to claim 6 or 7, wherein a rotating body of the magnetic encoder is fixed to a rotating portion of a motor having a field permanent magnet, and the fixed body of the magnetic encoder is fixed to the motor. Servo motor characterized by being fixed to.

Images