JPH0310079B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation sensor that detects rotation, and particularly to an electromagnetic induction type rotation sensor.

The pick-up coil in an electromagnetic induction type rotation sensor must generate a detectable level of voltage as an electrical signal in response to rotation due to changes in magnetic flux due to rotation, so the number of turns ranges from several thousand turns to 10,000 turns. The winding process requires several turns, and the winding process takes time, which is disadvantageous in terms of production.

Therefore, an object of the present invention is to obtain a rotation sensor that can be manufactured without requiring a winding process for a pickup coil.

In order to achieve the object, the present invention creates a flat pickup coil by etching a flexible printed circuit board, and also amplifies the electric signal generated in the pickup coil and outputs a rotation signal. The gist of the configuration is that a semiconductor circuit is formed on the flexible printed circuit board.

Therefore, with this configuration of the present invention, since the pickup coil is formed by etching the flexible printed circuit board, there is no winding process, and moreover, a flat coil with a relatively small number of windings is formed using the flexible printed circuit board. The voltage of the electrical signal corresponding to the rotation generated by the motor is amplified by an amplifying semiconductor circuit provided on the flexible printed circuit board and output as a rotation signal, which reaches a detectable output level. In addition to being able to be used as a rotation sensor and achieving the intended purpose, both the pick-up coil and the amplification semiconductor circuit can be formed on a flexible printed circuit board and assembled, making it easy to handle. Due to its flexibility, it can be installed in a narrow space, which is advantageous for downsizing the rotation sensor, and has extremely excellent practical effects.

Further, preferably in the present invention, the amplification semiconductor circuit includes a transistor, the base bias resistance of which is connected between the base and the collector of the transistor, and the pull-up resistance connected to the collector connected outside the sensor. If the number of external connection terminals is two, the connection between the rotation sensor and the outside can be simplified. In the present invention, preferably, if the electrical terminal for external connection is hermetically sealed with a disk-shaped Gol seal material, the assembly can be completed instantly and the assembly time is reduced compared to the case where the electrical terminal is sealed by filling with epoxy resin or the like. can be shortened.

An embodiment of the apparatus of the present invention will be described below based on the drawings.

The electromagnetic induction type rotation sensor 10 has a protrusion 14 formed on the other end of a magnetic iron yoke 13, one end of which is attracted to a permanent magnet 12 mounted in a synthetic resin housing 11, as shown in the fourth figure. The protrusion 14 of the yoke 13 and each tooth in the magnetic circuit formed by the permanent magnet 12 are arranged so as to be able to face each tooth 16 that rotates together with the rotating body 15 that is a rotation detection target, and is formed by the permanent magnet 12 due to the rotation of the rotating body 15. By changing the magnetic path gap formed between 16 and 16, the change induces a voltage, which is a rotation signal, in the pick-up coil 17 installed in the housing 11, and generates an electric signal corresponding to the rotation of the rotating body 15, which is the object to be detected. Output.

The pick-up coil 17 is formed together with an amplifying semiconductor circuit 19 on a single flexible printed circuit board (generally called FPC) 18 made of polyamide resin, for example. Gap between foil and copper foil
If the flexible printed circuit board 18 is etched into a spiral shape with a thickness of 0.1 mm, each pickup coil 17 of the size shown in FIGS. 5 and 6 can be obtained.
About 25 turns can be formed on each side of the front and back surfaces of the flexible printed circuit board 18, and about 50 turns of the pick-up coil 17 can be formed on the front and back sides in total. The pick-up coils 17, 17 formed of the flexible printed circuit board 18 shown in FIG.
Each pick-up coil 1 when 7 are stacked and installed
7 and 17 have patterns connected in series with the same winding direction.

The pick-up coil 17 shown in FIG. 6 is formed on both the front and back surfaces of the flexible printed circuit board 18, and the portion 20 of the flexible printed circuit board 18 is attached to the flexible printed circuit board 1 shown in FIG.
8, it is folded as shown in the first figure and installed in the housing 11, and in the installation,
The pick-up coils 17 formed on both the front and back surfaces of the flexible printed circuit board 18 have patterns connected in series, each having the same winding direction. The flexible printed circuit board 18 shown in FIG. 6 is also arranged with the semiconductor amplifier circuit 19 shown in FIG. 5 in the same manner, and is omitted in FIG. As shown in FIG. 7, an amplifying semiconductor circuit 19 that amplifies the voltage generated in the pick-up coil 17 and outputs a rotation signal has one end of the pick-up coil 17 connected to the base end of an NPN type transistor 23 via a coupling capacitor 22. The other end of the pickup coil 17 is connected to the transistor 2.
The base bias resistor 24 of the transistor 23 is connected between the base and the collector of the transistor 23, and is formed on the flexible printed circuit board 18. and each collector end of the transistor 23,
Copper foils 25 and 26 (shown in the fifth figure) of the flexible printed circuit board 18 connected to the emitter end constitute electrical terminals for external connection via a normal printed circuit board 27 mounted in the housing 11 as shown in the first figure. It is drawn out of the housing 11 by two lead wires 28 and 29. and lead wire 28
The power supply voltage Vcc is supplied to the lead wire 28 side via a pull-up resistor 30 by an external electric circuit provided outside the housing 11, and the lead wire 29
The side is grounded.

In Fig. 1, 31 is a sleeve made of synthetic resin, 32 is a seal ring, and 33 is a disc-shaped rubber seal, which has holes into which lead wires 28 and 29 are press-fitted, and the lead wires 28 and 29 are pulled out. The screw 34 is press-fitted into the closed part of the housing 11.
The iron lid 3 is screwed onto the housing 11 by
5, it is firmly held and exhibits sealing performance, and also prevents the yoke 13 and the permanent magnet 12 from rattling. In addition, the housing 11 has a first
As shown in the figure, a metal sleeve 36 is provided, and a hole 37 in the sleeve 36 is an insertion hole for a mounting bolt (not shown) for fixing the sensor 11.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention;
FIG. 2 is a left side view of FIG. 1, FIG. 3 is a right side view of FIG. FIG. 6 is an explanatory diagram showing another example of the configuration of the flexible printed circuit board in the device of the present invention, and FIG. 7 is an explanatory diagram showing another example of the configuration of the flexible printed circuit board in the device of the present invention. FIG. 2 is an electrical circuit diagram showing a semiconductor circuit. 10... Rotation sensor, 17... Pick-up coil, 18... Flexible printed circuit board, 19
...Semiconductor circuit for amplification.

Claims (1)

[Scope of Claims] 1. In a rotation sensor that detects rotation by electromagnetic induction, a pick-up coil is formed of a flexible printed circuit board, and an amplifying semiconductor that amplifies the electric signal generated in the pick-up coil and outputs a rotation signal. A rotation sensor with a circuit provided on the flexible printed circuit board. 2. The amplifying semiconductor circuit includes a transistor, the base bias resistor of which is connected between the base and collector of the transistor, and the pull-up resistor connected to the collector connected outside the sensor. The rotation sensor according to claim 1, characterized in that the number of terminals is two. 3. The rotation sensor according to claim 2, wherein the external connection electrical terminal is hermetically sealed with a disk-shaped rubber sealing material.