JPH05312597A - Position detector - Google Patents

Abstract

PURPOSE:To easily and highly accurately adjust the gap between a light receiving element and slit plate within a prescribed range. CONSTITUTION:This detector is provided with a slit plate 15 through which numerous slits 15a are formed at nearly regular intervals and a detecting means 2 equipped with a light emitting and receiving elements and can be moved relatively to the plate 15 and performs positioning based on a signal obtained when the light from the light emitting element is made incident to the light receiving element through the slits 15a. In addition, the means 25 is constituted in such a state that the means 25 can be rotated around one point 25b on an arm section 25a attached to the means 25 so that a gap can be formed between the light receiving element and plate 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a slit plate in which a large number of slits are formed at substantially equal intervals, and a detection means having a light emitting element and a light receiving element and movable relative to the slit plate. The present invention relates to a position detection device that performs positioning by a signal when light from the light emitting element enters the light receiving element through the slit.

[0002]

2. Description of the Related Art A conventional position detecting device of this type is a floppy disk drive device (hereinafter referred to as a floppy disk drive device) for recording and reproducing information on and from a flexible magnetic disk used as an external storage device of a computer, so-called floppy disk. It is used for head position control of FDD).

In recent years, the capacity of the FDD has been rapidly increased, and accordingly, high density recording has been required. In order to perform this high-density recording / reproducing, it is necessary to control the head position with high precision.

A motor is used as a head positioning drive source, but recently, an inexpensive voice coil motor (hereinafter, referred to as
VCM) is used. When this VCM is used as a head positioning drive source, in order to control the relative position between the disk and the head, for example, as shown in FIGS. 4 and 5, the slit plate 15 is directly attached to the chassis 11, and the light emitting element of the sensor 25 is attached. The light emitted from 25-a is incident on the light receiving element 25-b through the slit 15a, and the signal can be used to detect the movement amount of the carriage (not shown) to which the head and the sensor are attached. It is being appreciated.

In this case, it is necessary for the sensor and the slit plate to be accurately positioned and mounted in order to perform precise relative position control between the disk and the head.
A large number of slits are formed on the slit plate at regular intervals, and the number and arrangement of the slits are provided corresponding to the tracks formed on a medium such as a floppy disk.

[0006]

However, in the above-mentioned conventional example, the gap X between the sensor 25 and the slit plate 15 does not reach the predetermined value due to the mounting error of the sensor 25 and the mounting error of the slit plate 15 with respect to the carriage.
Does not have the desired waveform.

In such a case, a change in the waveform amplitude, a phase shift, etc. occur, the gain intersection of the control system using the encoder in which the sensor and the slit plate are combined changes, the positioning accuracy deteriorates, and the sensor is mounted. There is a problem in that the position detection device becomes unreliable due to a delay in the reset ring time when the carriage moves to the target track and stops, a change in the disturbance resistance characteristic against an impact applied from the outside of the device, and the like.

It is an object of the present invention to obtain a position detecting device that solves the above problems.

[0009]

The present invention comprises a slit plate in which a large number of slits are formed at substantially equal intervals, and a detection means having a light emitting element and a light receiving element and movable relative to the slit plate. In a position detecting device that performs positioning by a signal when light from the light emitting element is incident on the light receiving element through the slit, the detecting means so that the gap between the detecting means and the slit plate can be changed. Since the arm is provided so as to be rotatable about one point of the arm portion provided in the detecting means, the gap between the detecting means and the slit plate can be suppressed within a predetermined range. As a result, the detection output can have a desired waveform, the gain intersection of the control system using the encoder can be stabilized, the positioning accuracy can be improved, and good position detection can be performed.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. Embodiment 1 FIG. 1 and FIG. 2 show Embodiment 1 of the present invention, and FIG. 1 is a drawing which best shows the features of the present invention. In FIG. 1 and FIG. 2, a disc cassette (not shown) is inside a chassis 11. It is mounted by being guided by the cassette holder 12 arranged in. The medium 10 is mounted inside the disc cassette. A shutter opening / closing lever 16 for opening / closing a shutter for covering the opening of the medium 10 and loading / unloading the disc cassette is provided at the corner of the cassette holder 12.

A head load assembly 17 is disposed adjacent to the VCM 13 in order to bring the magnetic heads 8 and 9 into contact with or away from the medium 10. A solenoid is used for the head load assembly 17, and the magnetic heads 8 and 9 are brought into contact with the recording surface of the medium 10 when energized.
When the power is not supplied, the magnetic heads 8 and 9 are separated from the surface of the medium 10.

Next, the magnetic head seek mechanism will be described. Inside the yoke 18 of the VCM 13 as a driving source, the magnet 19 and the coil 2 attached to the carriage 1 are arranged.
0 is provided. When a current flows through the coil 20, the carriage 1 is moved by the interaction between the magnetic field generated by this energization and the magnetic field of the magnet 19.

A head arm 3 is attached to the carriage 1. A plurality of rollers 21 are attached to one side of the carriage 1 at an arbitrary angle. The preload 22 is composed of a roller 22a and a load spring 22b for pressing the roller against the second guide bar 24. The carriage 1 is provided between the guide bars 23 and 24 via the rollers 21 and 22a and the roller spring 22b. It is elastically supported by, and is guided by the guide bars 23 and 24 to seek in a direction toward and away from the center of the medium 10, and moves to a predetermined track position.

In the carriage 1 and the head arm 3,
Magnetic heads 8 and 9 are provided respectively, and the magnetic heads 8 and 9 record and reproduce information on both sides of the medium.

A thin slit plate 15 formed by etching or the like is fixed to the chassis 11 in parallel with the guide bars 23 and 24 via a mounting plate 50. A large number of slits 15a are formed in the slit plate 15 at substantially equal intervals, and the light emitted from the light emitting element of the sensor 25 as the detection means attached to the carriage 1 is guided to the light receiving element through the slit 15a. Positioning is performed by the light receiving signal of the light receiving element.

The sensor 25 has an arm portion 25a,
One end of the arm portion 25a can be rotated about the rotation center 25b in the directions of arrows A and B, and an arm portion 25c is provided on the other end side of the arm portion 25a. It is fixed to the carriage 1 with a fixing screw 60 which is passed through the long hole 25d. According to this structure, the sensor 25
When the sensor is rotated in the directions of arrows A and B by observing the output waveform of the above, and the desired output waveform is obtained by changing the gap with the slit plate 15, it may be fixed to the carriage 1 with the fixing screw 60.

By the way, when the sensor 25 is rotated about the rotation center 25b, an angle is generated between the sensor 25 and the slit plate 15. However, when the rotation center 25b is separated from the main body of the sensor 25, the angle is generated. It is extremely small and does not pose any problem.

Next, the control of the recording / reproducing apparatus to which the position detecting apparatus of the present invention is applied will be described with reference to the block diagram shown in FIG. In FIG. 3, based on a command signal input by an input means such as a keyboard (not shown) and data stored in an internal memory or the like, the microcomputer 100 causes the magnetic head 8,
The destination of 9 is decided. The VCM 13 is driven via the adder circuit 101 and the power amplifier 102 with the determined movement instruction a as one element.

When the VCM 13 is driven, the carriage 1 is moved along the guide bars 23 and 24 by the interaction between the current flowing through the coil 20 and the magnet 19.
When the carriage 1 is moved, the sensor 25 provided integrally with the carriage 1 and the slit plate 15 fixed to the chassis 11 interact with each other to cause the carriage 1 to move.
Information about the movement of, for example, 90 degrees out of phase 2
The two signals φA and φB are output from the encoder 26. The output signals φA and φB of the encoder 26 are first input to the differential amplifier 103 in the subsequent stage, and rough positioning of the head position is performed with reference to the intersection of both signal waveforms, that is, the point where the phase difference is zero. The output of 103 is input to the adding circuit 101 in the subsequent stage as a coarse position signal b.

The output signal of the encoder 26 is input to the comparators 104 and 105 in the subsequent stage and compared with a predetermined value, and the output thereof is input to the track counter 106 in the subsequent stage to forward or reverse. Counting is performed, and the output of the track counter 106 is input to the microcomputer 100 as a current position signal c indicating which position of the track the head is currently on.

Information on the moving speed of the carriage detected by the electronic tachometer 150 is input to the phase compensating circuit 108, and the signal d phase-compensated by the phase compensating circuit 108 is input to the adding circuit 101 to cause a phase shift. To prevent the occurrence of oscillation.

Further, an output signal f relating to the moving speed of the carriage detected by the electronic tachometer 150 is input to the microcomputer 100 and the differentiating circuit 109 for speed control. Then, the output signal of the differentiating circuit 109 is compared with a predetermined value in the comparator 110 at the subsequent stage. When the speed fluctuation exceeding the reference value of the comparator 110 occurs, the output signal e from the comparator 110 is applied to the microcomputer 100, for example, writing is prohibited, and data destruction due to impact is prevented.

On the other hand, when the servo information of the track recorded on the medium 10 is detected by the magnetic heads 8 and 9 themselves, this detection signal is amplified by the amplifier 111 and input to the position error detection circuit 112. The position error detection circuit 112 outputs the track following position error signal g to the microcomputer 1.
00 is input.

In this way, the coarse position signal b and the phase-compensated speed signal d directly input to the adder circuit 101, the current position signal c, the speed signal f input to the microcomputer 100, and the speed change f Accurate position control of the carriage 1 and the magnetic heads 8 and 9 moved integrally with the carriage 1 is performed by a movement command a output from the microcomputer in accordance with the shock prevention signal e and the track following servo signal g.

For example, when the count value of the target position in the microcomputer 100 and the count value obtained by the track counter 106 as the sensor 25 moves, the output signal a of the microcomputer 100 becomes "0", and the differential amplifier When the output signal b of 103 is "0", that is, the head stops at the track position corresponding to the predetermined slit position,
Head position control can be performed.

In this case, since the gap X between the light receiving element 25b of the sensor 25 and the slit plate 15 can be suppressed within a predetermined range, the output of the sensor 25 can have a good waveform.

Although the above embodiment is applied to the disk device, the present invention is not limited to this and can be widely applied to devices requiring position detection.

[0028]

As described above, according to the present invention, the detecting means is configured to be rotatable about one point of the arm portion provided on the detecting means so that the gap between the detecting means and the slit plate can be varied. Therefore, variations in the gap between the detection means and the slit plate due to errors in mounting the sensor on the carriage, errors in mounting the slit plate, etc. can be easily and accurately absorbed, and the detection output can have a desired waveform. it can. As a result, the waveform amplitude becomes stable and the phase becomes accurate,
The gain intersection of the control system that uses the encoder is stable, the positioning accuracy is improved, the settling time when the carriage moves to the target track and stops, the settling time is shortened, the disturbance resistance characteristics against impacts applied from outside the device are improved, etc. There is an effect that the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a recording / reproducing apparatus equipped with a position detecting device according to the present invention.

FIG. 2 is a perspective view of a main part of FIG.

FIG. 3 is a block diagram of a recording / reproducing device to which the position detecting device of the present invention is applied.

FIG. 4 is a perspective view showing a conventional position detecting device.

FIG. 5 is an enlarged view of a sensor unit.

[Explanation of symbols]

 15 slit plate 15a slit 25 sensor (detection means) 25a arm portion 25b rotation center of sensor X gap

Claims (1)

[Claims] 1. A light from the light emitting element, comprising: a slit plate having a large number of slits formed at substantially equal intervals; and a detection means having a light emitting element and a light receiving element and capable of moving relative to the slit plate. In the position detecting device for positioning by the signal when the light enters the light receiving element through the slit, the detecting means is provided in the detecting means so that the gap between the detecting means and the slit plate can be changed. A position detecting device characterized in that it is configured to be rotatable about one point of an arm portion as a fulcrum.