JPS6024413A - Electromagnetic-conversion detecting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the structure of a magnetoelectric conversion detection device when used as a pulse counter or the like.

A magnetoelectric conversion detection device is a device using a magnetoelectric conversion element that detects changes in electrical resistance caused by changes in a magnetic field. Conventionally, as this type of device, one using electromagnetic induction, one using a semiconductor magnetoresistive element, etc. are known. Near M, an element in which a ferromagnetic thin film resistor such as Ni or CO is formed on a glass substrate is also used. This type of ferromagnetic thin film resistor has the following properties: When the ferromagnetic thin film is magnetized by an external magnetic field,
The resistance value changes depending on the direction of magnetization and the angle formed by the current.

The resistance is maximum when the direction of magnetization and the direction of current are parallel, and becomes small when they are perpendicular to each other.

Taking advantage of this property, magnetoresistive elements are used in non-contact pulse counters and the like.

Conventionally, non-contact pulse counters have mainly used photointerrupters, but because the response characteristics of photoelectric elements are slow, response signals with a good S/N ratio cannot be obtained with high-frequency pulses. There is also the problem that if dust adheres to the area around the photointerrupter, it will no longer respond.

Magnetic resistance elements have fast response characteristics, and dust does not change the sensitivity unless it is magnetic dust. Therefore, it has recently attracted attention and has been applied to various types of blood.

The configuration of a pulse counter, which is an example of its application, is shown in FIG. Magnetic comb on the outer periphery! A bias magnet 4 having an N pole on the upper side is superimposed on a disc-shaped pulse plate 2 having an I2a so as to overlap the comb 1i2a, and a ferromagnetic resistance element l is arranged. The ferromagnetic resistance element l consists of two ferromagnetic thin film resistors MR whose current directions intersect at a certain angle.
, and MB2 are lined up in the rotation direction, and the difference in resistance is
The voltage is converted by the resistor bridge with the connected resistors R3 and R4 and the power supply E, and is output from the output terminal out. When the pulse plate 2 rotates, the position of the comb teeth 2a changes, the direction of the magnetic field relative to the thin film resistors MHI and MB2 changes, and an output voltage signal appears.

This pulse counter is used, for example, in an aperture position detection device of an automatic aperture device of a camera.

Many position detection devices of this type require high accuracy. Normally, the pulse plate is used by being rotated at high speed from the diaphragm drive unit through a speed increasing gear train. However, Pal
When the bias magnet is close to the pulse plate, an attractive force is generated between the magnetic comb teeth of the pulse plate and the magnet. Therefore, each time the comb teeth pass over the magnet, it operates intermittently, creating running resistance for the gear train. In addition, since the pulse plate is installed at the final stage of the speed-up gear train, even a small amount of running resistance has a large effect on the running characteristics17, and not only smooth rotation cannot be obtained, but also repeated intermittent The operation is also detrimental to gear train wear.

By the way, Japanese Unexamined Patent Publication No. 55-SOASO discloses an invention in which running resistance caused by such suction force is applied to a speed regulating mechanism. However, if this invention is implemented, when the vehicle starts running from a state of initial stop, energy sufficient to overcome the attractive force between the magnet and the pulse plate will be consumed. As a result, the start of running is slow and it takes a long time to reach stable running. Therefore,
Standing 1. This is inconvenient in that it requires a mechanism to correct the delay time.

The present invention overcomes the disadvantages and disadvantages of such conventional magnetoelectric conversion detection devices.
The purpose of this invention is to provide a magnetoelectric transducer that eliminates this inconvenience and provides extremely stable running and good response characteristics.

In order to achieve this goal, the present invention provides a magnetoelectric transducer that uses a magnetoresistive element to detect changes in the magnetic field caused by a magnetic body in a fixed position and a moving magnetic body facing the fixed position magnetic body. The magnetoelectric conversion detection device is characterized in that the arrangement pitch in one of the magnetic bodies in the moving direction is a natural number multiple of the arrangement pitch of the other magnetic body.

Embodiments of the present invention will be described in detail below to clarify the above configuration.

FIG. 2 shows an embodiment of the invention.

A magnetic comb tooth 2a is formed on the outer periphery of the pulse plate 2, and the comb tM2a faces a bias magnet 1O via a ferromagnetic resistance element 1.

The length of the bias magnet lO in the direction in which the pulse plate 2 rotates (arrow R) is n times the length p corresponding to the pitch of the unevenness of the comb teeth 2a.C1=np, n=1.2. 3. ,
,Natural number). The figure shows the case where sentence=p.

In other respects, the configuration of the ferromagnetic resistance element l is the same as that of the conventional one, so a repeated explanation will be omitted.

In a pulse counter with such a configuration, when the pulse plate 2 rotates, the combs tM2a of the pulse plate 2 move toward the bias magnet lO.
The position facing the is successively displaced. The length of the tops (or grooves) of the opposing comb teeth and the length of the bias magnet are always constant. That is, when one top of the comb teeth is within the range of the bias magnet 1o, and when two tops are within the range of the bias magnet 1o,
When it is in the range of 0, the length of the bias magnet 10 and the comb peak facing each other is constant.

Therefore, the bias magnet and the comb teeth are at a specific position i? When you are in a relationship, you no longer have a strong attraction to others. Therefore, the pulse plate does not rotate intermittently.

The pulse plate on the L lift male side is a rotating body, but may be a unidirectionally moving body. m magnetized on the magnetic comb teeth 2a
It can be carried out even if the Further, the magnetic resistance element and the bias magnet may be arranged outside the outer periphery of the pulse plate.

FIG. 3 is an example in which the magnetoelectric conversion detection device of the present invention is applied to position detection of an automatic aperture device of a camera.

11 is the lens aperture unit, 121f aperture blade, 1
3 is the aperture signal lever, 14 is a coil spring and signal lever 1
3 counterclockwise. 15C automatic aperture lever,
Reference numeral 16 indicates a diaphragm lever that operates the automatic diaphragm lever 15.

17 is an aperture interlocking lever that drives the aperture signal lever 13. A slot 17a is provided in the center, and these slots are engaged with pins 18 and l8', respectively, and are slidable. Interlocking lens <-171±, has an aperture drive part 17b that engages with the aperture signal lever 13 to control the aperture, has a locking part 17c at the center side part, and has a charge part 1 at the lower end.
7d and along one side thereof a rack 17e.
is formed. Engages with and interlocks with the locking portion 17c/<
-17 is engaged by the shaft 20.
, rotatably supported. The interlocking lever 17 is held at the locking position by the locking t<-191fJf screw 21. Reference numeral 22 designates a release button, which has a locking lever operating portion 22a that contacts the locking lever <-19 and rotates it against the force of the spring 21. In addition, the release button 22
A photometric switch 23 is disposed on the side of the photometric switch 23, and the release button 22 is provided with a photometric switch operating section 22b for operating the photometric switch 23. Reference numeral 24 indicates a charge lever that charges the interlocking lever 17° in conjunction with a member not shown. The interlocking mechanism 8-17 is connected to a speed regulating mechanism which is synchronously driven to increase speed. This speed regulating mechanism includes small gear trains G11162 and G3 connected to the rack 17e of the interlocking lever 17, and a stop wheel 26 and a pulse plate 27 are attached to the shaft 25 of the last gear.

The stop wheel 26 has saw teeth formed on its outer periphery.

A stopper 31 that engages with and stops the stop wheel 26 is supported by a shaft 31a, and has a claw portion 31b that engages with the saw teeth of the stop wheel 26, a cover portion 31c made of a magnetic material, and a locking portion 31d. The stopper 31 is provided with a spring 30 that always biases it clockwise. An electromagnet 3 is provided at a position facing the cover portion 31c.
2 is provided and attracts the stopper 31, and when the electricity is turned off, the stopper 31 is moved to the shaft 3 by the elastic force of the spring 30.
Rotate clockwise around 1a to engage the claw portion 31b with the saw teeth of the stop wheel 26. Reference numeral 33 denotes a charge engagement pin for returning the stopper 31 to the charge position, which is linked to a winding member (not shown) and engaged with the locking portion 31d.

The rotating pulse plate 27 has a comb-toothed outer peripheral portion made of a magnetic material. A magnetic resistance element 29 integrally formed with a magnet 28 for generating a bias magnetic field is disposed on the back side (or front side) of the pulse plate 27. The width of the bias magnet 28 is an integral multiple of the pitch of the comb teeth. Further, the magnetoelectric conversion detection device 35 is provided with a circuit 34 consisting of a resistance bridge and a power source, as shown in the above example, in order to obtain a signal output from the magnetoresistive element 28.

FIG. 4 is a block diagram of a control circuit for such an automatic diaphragm device.

In the figure, 53 is an operational amplifier, 54 is a Schmitt trigger circuit, 55 is a pulse counter, 56 is a digital comparator, 57 is a photometric calculation circuit, 32 is an electromagnet shown in FIG. 3, and 35 is a magnetoelectric conversion detection device. .

In the automatic diaphragm control device described above, when the release button 22 is pressed, the photometry switch operating section 22b first closes the photometry switch 23, and thereby the photometry calculation circuit 57 is activated. At the same time, the electromagnet 32 is also energized and the stopper 31
The cover portion 31c is sucked. Furthermore, release button 22
When pushed in, its tip 22a comes into contact with the end of the locking lever 19 and rotates the locking lever 19 clockwise against the force of the spring 21. At the same time, the engagement IL pin 33, which is interlocked by the interlocking member (not shown) of the release button 22, is removed from the engagement state (the state shown in the drawings). At this time, the electromagnet 32
Since the suction force of the spring 30 is stronger than the biasing force of the spring 30, the striker 3
1 remains stationary. The interlocking lever 17 is the engagement 1L portion 1
7c and the lever 19 are disengaged, so the aperture signal lever 13 is rotated by the biasing force of the spring 14 and is inserted into the slot 17a which is slidably engaged with the pin 18.l8'. along the line in the L direction. When the 8-17 moves in the 1-hi direction, the small gear train GI moves in conjunction with the movement of the rack 17e.
1IG2 and G3 are interlocked with speed increase to rotate the stop wheel 26 and pulse plate 27 at the final stage. At this time, the magnetoresistive element 29 uses the combs and numbers of the pulse plate 27 passing over the element surface as a condensed sine wave voltage, and performs magnetoelectric conversion and detecting device 3.
Output from 5.

This output value is amplified by an operational amplifier 53 and shaped into a waveform by a Schmitt trigger circuit 54. The pulse waveform is counted as a pulse by the pulse counter 55 by λ1. This count 4di is input to the digital comparator 56.

On the other hand, the count value corresponding to the aperture value (Ay value) calculated in advance by the photometric calculation circuit 57 is also input to the digital comparator 56 . When the electromagnet 32 is turned off when these two values become equal, the stopper 31 rotates and the pawl 31b engages with the saw teeth of the stop wheel 27. Then, the interlocking lever 17 stops at the position where the desired aperture value is selected.

During these series of operations, the unevenness of the attractive force between the bias magnet 28 and the pulse plate 27 is eliminated, so the start of the operation is sharp, and there are no intermittent movements during running, resulting in smooth operation. Indicates driving characteristics. Therefore, the spring for stopping the vehicle does not need to be very strong, and the overall size can be reduced.

There is little wear on each part, and there are no abnormal sounds. Moreover, a control device with short control time can be obtained.

FIG. 5 shows the running characteristics of the pulse plate of the automatic diaphragm device according to the present invention and the running characteristics of the pulse plate of the conventional device. The former is shown by a solid line, and the latter by a dotted line. The pulse plate of the device of the present invention is in a state where the rotation speed is more than +11<stable,
It can be seen that there is little change in the rotation speed after that.

[Brief explanation of the drawing]

Fig. 1 is a front view of a conventional magnetoelectric conversion detection device, Fig. 2 is a partial front view of a magnetoelectric conversion detection device to which the present invention is applied, and Fig. 3 is an implementation in which the device of the present invention is applied to an automatic aperture device of a camera. A front view of the example, FIG. 4 is a control circuit block diagram thereof, and FIG. 5 is a diagram explaining the running characteristics of the pulse plate. l is a magnetoresistive element, 2 is a pulse plate, 2a is a comb tooth, lO
is the bias magnet, P is the length of the bias magnet, and P is the arrangement pitch of the comb teeth of the pulse plate. Figure 1 Figure 4 Figure 3 f Figure 1 - Running #8 light

Claims (1)

[Claims] (+) In a magneto-electric transducer that uses a magnetoresistive element to detect changes in the magnetic field caused by a magnetic body in a fixed position and a moving magnetic body facing the fixed position magnetic body. . A magnetoelectric conversion detection device, wherein the magnetic weight of one of the magnetic bodies in the moving direction is a natural number multiple of the arrangement pitch of the other magnetic body.