JPS5841310A - Magnetism detecting device - Google Patents

Abstract

PURPOSE:To enhance reliability and manufacturing property and to make it possible to perform highly accurate magnetism detection, by bridging a sensor on a through hole of a substrate and attaching it thereto, and bringing a magneic thin film closer to the sensor from the lower part through said hole. CONSTITUTION:The magnetism detecting device 9 comprising the sensor 92 which is supported by a glass substrate 91 is bridged on the through hole 8 in the substrate 7. The sensor 92 is directed to the through hole 8 and connected to a printed wiring around the through hole 8. A rotary disk 3 is positioned so as to face the through hole 8. The magnetic thin film 4 which is supported by the outer surface of the rotary disk 3 is brought to the sensor 92 as closely as possible. When the rotary disk 3 is rotated by a motor 1, the sensor 92 sequentially detects magnetized parts 5 of the magnetic thin film 4. The change in internal resistance of the sensor 92 is detected by a voltage comparator 10, and the number of rotation of a rotary shaft 2 is measured. Since lead wires are not required, the reliability and manufacturing property are enhanced and the highly accurate detection of the magnetism is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic detection device, and more particularly to a magnetic detection device suitable for detecting a magnetized portion of a magnetic thin film in a cell.

It is conventionally known to detect a magnetized portion of a magnetic thin film using, for example, a sensor made of a Hall element to detect the rotation angle and rotation speed. Further, the sensor is connected by a lead wire to wiring on a substrate that supports the sensor portion.

However, the voltage that can be detected by the cell is 100 mV
Since it is very small, less than pp, there is a risk of malfunction due to external noise picked up by the lead wire.

Furthermore, the work of connecting the lead wires and the wiring on the board is extremely difficult, and poor connections and variations in connection status also affect the magnetic detection device.

One way to solve this problem is to increase the voltage applied to the sensor to some extent, but there are limits due to the voltage and current capacity of the power supply and sensor.

The present invention has focused on the above points, and by connecting the sensor to the printed wiring of the board with or without lead wires and bringing the magnetic thin film sufficiently close to the sensor, it is strong against external noise, has high reliability,
The object of the present invention is to obtain a magnetic detection device that is highly manufacturable and enables highly accurate detection.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In the drawing, 1 is an electric motor, 2 is a rotating shaft of the electric motor 1, and 3 is a rotating plate attached to this rotating shaft 2, and a magnetic thin film 4 is supported on the outer peripheral surface of the rotating plate. This magnetic thin film 4 has a large number of magnetized parts 5 arranged in parallel in the circumferential direction.

This magnetized portion 5 is shown by multiple lines in FIG. If angle detection is performed in units of 1 degree, there are 360 magnetized portions 5 at equal intervals.

Reference numeral 6 denotes one end bracket of the electric motor 1, 7 a substrate made of a ceramic plate and attached to the end bracket 6, and 8 a rectangular opening provided in the substrate 7.

Also attached to this board 7 are a magnetic detector 9, a voltage comparator 10, capacitors 11 and 12, and a transistor 13 constituting a constant voltage device for sending a constant voltage to the sensor 92 of the magnetic detector 9. . Patterned wiring (not shown) is printed on the surface of the substrate 7 to electrically connect these components 9°1o, 11, 12, and 13.

The magnetic detector 9 includes a glass substrate 91 having a thickness of about 0.6 to 1 mm, and a surface (first surface) of this glass substrate 91.
In this example, the sensor 92 is patterned and carried on the bottom surface (in the figure), which is optimal for detecting an angle of 1 degree. This sensor 92 is a so-called Hall element that senses magnetic flux and changes its electrical resistance. and,
The sensor 92 is electrically connected to the printed wiring on the substrate 7 by wireless bonding such as flip chip bonding or lead beam bonding.

Reference numeral 14 denotes a solder paste interposed between the substrate 7 and the sensor 92, and the solder paste 14 is melted using a heating furnace or microwave heating to connect the printed wiring of the substrate 7 and the sensor 92.

As is clear from FIG.
It is connected to the printed wiring on the periphery of the That is,
The sensor 92 can be viewed from below through the opening 8. Then, a portion of the rotary plate 3 is inserted into the through hole 8 from below the through hole 8, so that the magnetic thin film 4 is brought as close as possible to the sensor 92. Specifically, the distance between the sensor 92 and the magnetic thin film 4 is set to 100 microns or less. If the distance is longer than this, the sensor 92 detects that the magnetized part 5
reliable detection becomes impossible. In other words, it becomes impossible to obtain the voltage necessary to detect the angle. The size of the opening 8 is, of course, such that the magnetic thin film 4 does not come into contact with the substrate 7 when the magnetic thin film 4 is brought close to the sensor 92 by the distance described above.

In the above configuration, the rotating plate 3 is rotated by energizing the electric motor 1. When the rotating plate 3 rotates, the sensor 92 can sequentially detect the magnetized portions 5 of the magnetic thin film 4. A constant voltage of several volts is applied to the sensor 92 by a constant voltage device using a transistor 13, and the internal resistance of the sensor 92 changes due to the magnetism of the magnetized portion 5. By processing this change with the voltage comparator 10, the magnetized portion 5 can be detected.

Then, the voltage obtained by the magnetizing unit 5 is pulsed, and the rotation angle of the rotary shaft 2 is detected by counting the pulses, and the rotation speed of the rotary shaft 2 is detected by counting the number of pulses per unit time. can do.

If the signals obtained from this angle and rotational speed are applied to control the motor, the motor can be stopped at any position or the speed can be freely controlled.

According to the configuration of the embodiment, the sensor 92 can be directly attached to the through hole 8 of the substrate 7, so that the sensor 92 and other electrical components can be connected by wireless bonding.

Further, when long wires or lead wires are used, the device is easily affected by external noise, but in the above-mentioned embodiment, since there is no so-called lead wire, it is possible to provide a device that is resistant to noise and does not malfunction.

Furthermore, there is no need to worry about breakage of the lead wires or their connections.

Furthermore, as in one embodiment of the present invention, various electrical components and the sensor 92 are arranged on the same surface of the board 7 (the one shown is the top surface), so that printed wiring and electrical components on the board 7 and the printed circuit board 7 are This has the advantage that connection with wiring can be made in one step.

Furthermore, since the magnetic thin film 4 can be made as close as possible through the opening 8, the detection ability of the sensor 92 can be increased accordingly. This is due to the presence of the opening 8.

If there were no openings 8, it would be impossible to bring the magnetic film 4 closer to the sensor 92 than the thickness of the substrate 7, typically a few millimeters.

Sensor 92 without using glass substrate 91
If it can be attached on the substrate 7 alone, the magnetic thin film 4
The sensor 92 can be approached from above in the drawing. However, the sensor 92 is several microns thick and cannot be manufactured as a wire material, and in reality, the sensor 92 is made from a glass substrate 92.
1 by vapor deposition.

In other words, when manufacturing this type of sensor 92,
A glass substrate 91 is required, and when the magnetic thin film 4 is brought closer to the sensor 92 from above, it is physically impossible to bring it closer than the thickness of the glass substrate 91.

As mentioned above, the thickness of the glass substrate 91 is 0.6 at the thinnest.
It is about millimeters. When the sensor 92 and the magnetic thin film 4 are separated to this extent, magnetism can no longer be detected. For this purpose, a through hole 8 is provided so that the magnetic thin film 4 can be approached from below.

As explained above, according to the present invention, the sensor is mounted across the through hole of the board, and the magnetic thin film is approached to the sensor from below through the through hole, so the sensor is connected to the printed wiring of the board without lead wires. In addition, it is possible to obtain a magnetic detection device that can bring the sensor and the magnetic thin film sufficiently close to each other, has high reliability and manufacturability, and is capable of highly accurate detection.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional side view of the main part when the device of the present invention is attached to an electric motor, FIG. 2 is a plan view of the main part, and FIG. It is a sectional view taken along ■-■ in the figure.

Claims (1)

[Scope of Claims] 1. A rotating plate is attached to a rotating shaft, a magnetic thin film having a large number of magnetized parts is supported on the rotating shaft, and a sensor for detecting the magnetism of this magnetic thin film is supported. and a substrate, characterized in that the sensor is mounted across the through hole of the substrate, and a part of the rotary plate is inserted into the through hole in order to bring the magnetic thin film close to the sensor. magnetic detection device.