JPH0574001B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is used in a device, such as a magnetic disk device, in which the rotational motion of a motor is converted into the linear motion of a moving object, and is used to determine a specific position of the moving object. The present invention relates to a position detection device that detects with high accuracy.

[Prior art and its problems] For example, in a magnetic disk device, it is necessary to move the magnetic head to the innermost track position of the magnetic disk for initialization. It is designed to detect this and stop the movement of the magnetic head.

In small magnetic disk devices such as those used in electronic still cameras, the track pitch is as small as 100 μm, so it is necessary to detect the innermost track position with high precision.

Therefore, in the past, as shown in FIG. 4, an enlarging mechanism was provided to detect this initial position using a single position sensor. That is, the enlarged arm 70 is connected to the base 11 by the pin 72 at an internal division point of, for example, 1:5.
(fixed side), and the tip of the short arm side of the enlarged arm 70 is brought into contact with a protrusion 74 provided on the carriage 14, and in order to ensure this contact at all times, one end of the torsion spring 76 is attached to the enlarged arm. A screw 78 is engaged with the long arm of 70 and the other end is screwed into the base 11.
It was locked in. When the magnetic head 18 moves to the innermost track position, the enlarged arm 7
A transmission type photointerrupter 80 was disposed on the base 11 so as to detect the tip of the long arm of the camera.

This position detection device can detect the initial position of the magnetic head 18 with an accuracy five times greater than that of directly detecting the carriage 14.

However, since it is necessary to use the long expansion arm 70, the device becomes large, which is contrary to the demand for miniaturization of magnetic disk devices.

Therefore, as shown in FIG. 5, a position detection device using two position sensors is used. That is, by using the side surface of the carriage 14 as a reflective surface, and disposing a reflective photo interrupter 46 on the base 11 opposite to this, and detecting the position where the reflected light from the carriage 14 is no longer reflected, the magnetic head 18 can be adjusted. It is designed to detect the approximate initial position. On the other hand, the rotation of the spur gear 28 fixed to the drive shaft 26 of the step motor 24 is transmitted to the spur gear 82 via the spur gear 30, and the light shielding plate 84 is fixed to one end of the shaft of the spur gear 82. Notch 84a
A transmission type photo interrupter 80 is arranged on the base 11 corresponding to the edge of the light shielding plate 84, and after the approximate initial position is detected by the reflection type photo interrupter 46, the transmission type photo interrupter 80 opens the notch 84a. It was determined that the initial position was when it was detected.

However, two position sensors (reflective photo interrupter 46, transmissive photo interrupter 80)
It is necessary to use the above-mentioned methods, and it is also necessary to fine-tune each of them, resulting in high costs and complicated adjustments.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a position detection device that can be miniaturized and can accurately detect a specific position of a moving body moving in a straight line using one position sensor. It is in.

[Means for solving the problem] In order to achieve this object, the present invention uses a device that converts the rotational motion of a motor into a linear motion of a moving body, and detects a specific position of the moving body. The position detection device includes a rotating member that is rotationally driven by the motor and has a detected object provided thereon, and a rotating member that is disposed on a stationary side corresponding to the rotating member and that detects the detected object when the rotating member is at a predetermined rotational position. A non-contact type position sensor that detects a detection object, and a transparent part is formed, and when the moving object is located outside the vicinity of a specific position, a shielding part other than the transparent part connects the detected part and the non-contact type position. and the moving body so that the transparent part exists between the detected body and the non-contact position sensor when the moving body is located near the specific position. a shielding member fixed to the body, and the transparent part does not interfere with the detection by the non-contact position sensor when the transparent part is present between the detected object and the non-contact position sensor. For example, the shielding member is a notch portion of the shielding member, and the shielding portion prevents the detection by the non-contact position sensor when the shielding portion is present between the detected object and the non-contact position sensor. It is characterized by being

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows the main structure of a small magnetic disk device used in electronic still cameras and the like.

The magnetic disk 10 is mounted on a base 11 with screws 12.
The spindle motor 13 is placed on the chucking surface 13a of the spindle motor 13, which is mounted on the spindle motor 13, and is driven to rotate. A magnetic head 18 is fixed to the bridge portion 14b of the carriage 14 by screws 16, facing the lower surface (recording surface) of the magnetic disk 10.

The carriage 14 consists of this bridge section 14b and a guide section 14a perpendicular to the bridge section 14b. A guide bar 22 passes through the guide portion 14a via a bush 20, and the carriage 14 is movable in the axial direction of the guide bar 22. This movement causes the magnetic head 18 to move toward the magnetic disk 10.
move in the radial direction (tracking direction).

The carriage 14 is driven by converting the rotational motion of the step motor 24 into linear motion. That is, a spur gear 28 is fixed to the drive shaft 26 of a step motor 24 installed on the base 11, and a spur gear 30 is meshed with this spur gear 28.
One end of a shaft 31 is fixed to the center of the spur gear 30, and a lead screw 32 is externally fitted and fixed to the middle of the shaft 31. The shaft 31 is pivotally supported by a leg plate (not shown), and a spiral groove (not shown) is carved in the outer peripheral surface of the lead screw 32. On the other hand, a needle 34 is fixed to the lower surface of the tip of the bridge part 14b with its longitudinal direction aligned with the longitudinal direction of the bridge part 14b, and this needle 34 is engaged with the helical groove of the lead screw 32. There is.

Therefore, when the step motor 24 is rotationally driven, the lead screw 32 rotates via the spur gears 28 and 30 and the shaft 31, and this rotational movement is converted into a linear movement of the needle 34, and the carriage 14 is moved along the guide bar 22. will guide you in the tracking direction.

One end of a leaf spring 36 is fixed to the middle portion of the lower surface of the bridge portion 14b, and the lead screw 32 is held between the tip of the leaf spring 36 and the tip of the bridge portion 14b.

Therefore, rotation of the carriage 14 about the guide bar 22 is restricted, and the needle 34 is reliably engaged with the helical groove of the lead screw 32.

A disk 40 is attached to the tip of the shaft 31 with a screw 4.
1 and fixed concentrically. A C-shaped reflective surface 40a and an absorbing surface 40b, which is the remaining surface, are formed on the outer peripheral surface of the disc 40.

On the other hand, a U-shaped leaf spring 42 is fixed to the base 11 with a screw 44 corresponding to the disc 40, and
A reflective photo interrupter 46 is held between the letter springs 42 so as to be adjustable in a direction parallel to the guide bar 22. An adjustment screw 48 for fine adjustment in a direction parallel to the guide bar 22 is threaded through and in contact with a member (not shown) on the side surface of the U-shaped leaf spring 42 .

The reflective photo interrupter 46 is connected to the light emitting element 4
6a and a light receiving element 46b, and faces the circumferential surface of the disc 40.

A shielding member 50 is arranged between the disk 40 and the reflective photointerrupter 46. This shielding member 50 includes an arm portion 50a and an arm portion 50a.
It consists of a reflective U-shaped portion 50c bent at 90 degrees with respect to a and a notch 50b formed therein. This arm portion 50a has elongated holes 51, 51 whose longitudinal direction coincides with the longitudinal direction of the arm portion 50a. It is fixed so that the mounting position can be adjusted.

Next, adjustment of the position detection device will be explained.
This adjustment is performed in the following manner with the magnetic head 18 moved to the detection device, ie, the innermost track position.

That is, the height of the reflective photo interrupter 46 is made to match the height of the center of the shaft 31. Next, the screw 41 is loosened, the disk 40 is rotated by hand or using a jig, and the screw 41 is tightened at the initial (boundary) position where the absorption surface 40b is detected by the reflective photointerrupter 46. Next, loosen the screws 52, 52 and move the shielding member 50 toward its tip (toward the reflective U-shaped portion) until the absorbing surface 40b is at the initial (boundary) position detected by the reflective photo interrupter 46. Tighten the screw 52. Next, final fine adjustments are made using the adjustment screw 48. Adjustment using the adjustment screw 48 is relatively equivalent to fine adjustment of the mounting position of the shielding member 50 in the longitudinal direction.

Next, the operation of this embodiment configured and adjusted as described above will be explained.

In FIG. 2, the magnetic head 18 is connected to the magnetic disk 10.
In this state, the light emitted from the light projecting element 46a is reflected by the reflective U-shaped portion 50c and irradiated onto the light receiving element 46b. Therefore, the absorption surface 40b of the disk 40 is not detected. From this state, the carriage 14 is moved in the direction of the arrow X, that is, the magnetic head 18 is moved toward the innermost track, and when the magnetic head 18 comes near the innermost track position, the disc 40 and the reflective photo interrupter 46 are moved. A notch 50b is located between them, and the light emitted from the light projecting element 46a is reflected by the reflecting surface 40a and irradiated onto the light receiving element 46b. When the magnetic head 18 accurately reaches the innermost track position, as shown in FIG. 3, the absorption surface 40b of the disc 40 is located on the reflective photointerrupter 46 side, and the light emitted from the light emitting element 46a is The light is absorbed by the absorption surface 40b of the disk 40, and the reflected light is not detected by the light receiving element 46b.
Therefore, it is detected that the magnetic head 18 is at the innermost track position, and the rotation of the step motor 24 is stopped by a control circuit (not shown).

The relationship between the reflective photo interrupter 46 and the shielding member 50 of this embodiment corresponds to the relationship between the conventional reflective photo interrupter 46 and the side surface of the guide portion 14a shown in FIG. The relationship between the type photo interrupter 46 and the disk 40 is as follows.
A conventional transparent type photointerrupter 80 shown in the figure
The reflection type photo interrupter 46 of this embodiment fulfills the functions of both the conventional reflection type photo interrupter 46 and the transmission type photo interrupter 80.

Incidentally, in the above embodiment, a case has been described in which the position when no reflected light is detected by the reflective photo interrupter 46 is determined as the initial position, but conversely, when reflected light is detected by the reflective photo interrupter 46, the position is determined as the initial position. may be determined to be the initial position. This can be done by reversing the reflective and absorbing surfaces. That is, the reflective U-shaped portion 50c of the shielding member 50 may be used as an absorbing surface, the reflective surface 40a of the disk 40 may be used as an absorbing surface, and the absorbing surface 40b may be used as a reflective surface.

Furthermore, in the above embodiments, the case where the position sensor is of a reflective type has been described, but it may be of a transmissive type. In this case, for example, a hole (object to be detected) passing through the disc 40 in its diametrical direction is bored, and a light projecting element and a light receiving element are arranged so as to sandwich the disc 40 and the shielding member 50 therebetween. When the light from the light projecting element passes through this hole and the notch 50b of the shielding member 50 and is detected by the light receiving element, it is determined that the magnetic head 18 is at the initial position. Using the shaft 31 itself as a rotating member without providing this disc 40,
A hole may be made directly in this.

Further, in the above embodiments, the case where the position sensor is an optical sensor has been described, but the present invention may be a non-contact type sensor, and may be a magnetic sensor. In this case, for example, the shielding member is constituted by a magnetic shielding plate, and a small magnet is attached as the detected object instead of the absorption surface 40b. An arm may be provided as a rotating member instead of the disk 40, and this small magnet may be attached to the tip of the arm.

Furthermore, although the above embodiment describes a case in which the present invention is applied to a magnetic disk device, the present invention is not limited to this, and can be applied to various devices equipped with a mechanism for converting rotational motion into linear motion. .

[Effects of the Invention] In the position detection device according to the present invention, a detected object is provided on a rotating member that is rotationally driven by a motor, a non-contact type position sensor is provided on a stationary side corresponding to this rotating member, and the motor A shielding member is fixed to a movable body linearly driven by the movable body, and the shielding member shields between the rotating member and the non-contact position sensor in a predetermined range other than the vicinity of a specific position of the movable body, When the rotating member and the non-contact position sensor are not shielded by the shielding member, the non-contact position sensor can detect the detected object, and the detection indicates that the moving object is at a specific position. Since the sensor is designed to detect the position, only one non-contact position sensor is required, which simplifies the configuration.Therefore, it also simplifies installation and adjustment, which has the advantage of reducing costs. be.

Furthermore, since there is no need to provide an enlarging mechanism as in the prior art, there is an excellent effect that the device can be made smaller.

[Brief explanation of drawings]

1 to 3 relate to embodiments of the present invention, FIG. 1 is a perspective view showing the main part configuration when the present invention is applied to a magnetic disk device, and FIGS. 2 and 3 show a disk 40. FIG. 2 is a perspective view of a main part seen from the direction of arrow A in FIG. 1, showing the positional relationship between a reflective photo interrupter 46 and a shielding member 50. FIG. 4 and 5 are perspective views showing a conventional position detection device applied to a magnetic disk device. 10... Magnetic disk, 13... Spindle motor, 14... Carriage, 18... Magnetic head, 22... Guide bar, 24... Step motor, 32... Lead screw, 34... Needle, 36... Leaf spring, 40... Disk, 40a...
Reflective surface, 40b... Absorption surface, 42... U-shaped leaf spring, 46... Reflective photo interrupter, 46a
... Light emitting element, 46b ... Light receiving element, 48 ... Adjustment screw, 50 ... Shielding member, 50b ... Notch, 5
0c... Reflective U-shaped part.

Claims (1)

[Scope of Claims] 1. In a position detection device used in a device in which rotational motion of a motor is converted into linear motion of a moving body and detects a specific position of the moving body, a rotating member provided with a rotating member; a non-contact position sensor disposed on a stationary side corresponding to the rotating member and detecting the detected object when the rotating member is at a predetermined rotational position; and a transparent part. is formed, and when the movable body is located outside the vicinity of a specific position, a shielding part other than the transparent part exists between the detected part and the non-contact type position sensor, and the movable body a shielding member fixed to the movable body so that the transparent part is present between the detected body and the non-contact position sensor when the movable body is located near the specific position; The transparent part does not interfere with the detection by the non-contact position sensor when the transparent part exists between the detected object and the non-contact position sensor, and the shielding part does not interfere with the detection by the non-contact position sensor. A position detection device characterized in that when the shielding portion exists between the non-contact type position sensor and the non-contact type position sensor, the detection by the non-contact type position sensor is obstructed. 2. The rotating member is a rotating disc, the object to be detected is a light absorbing part formed on a part of the circumferential surface of the rotating disc, and the part of the circumferential surface other than the light absorbing part is a light reflecting part. The non-contact position sensor is a reflective photointerrupter in which a light emitting part and a light receiving part are arranged in parallel,
The shielding member is arranged to face the circumferential surface of the rotating disk, the predetermined rotational position is a position where the light absorbing portion of the rotating disk faces the reflective photointerrupter, and the shielding member is The transmitting portion is formed of a cutout portion, the shielding portion is formed of a light reflecting portion, the cutout portion is present between the rotating disk and the reflective photointerrupter, and Only when the light absorbing section faces the reflective photo interrupter, the light emitted from the light projecting section of the reflective photo interrupter is prevented from being detected by the light receiving section of the reflective photo interrupter, and the light detection 2. The position detecting device according to claim 1, wherein the position of the moving body when there is no vehicle is detected as the specific position. 3. The rotating member is a rotating disk, the object to be detected is a light reflecting part formed on a part of the circumferential surface of the rotating disk, and the part of the circumferential surface other than the light reflecting part is a light absorbing part. The non-contact position sensor is a reflective photointerrupter in which a light emitting part and a light receiving part are arranged in parallel,
The shielding member is arranged to face the circumferential surface of the rotating disk, the predetermined rotational position is a position where the light reflecting portion of the rotating disk faces the reflective photo interrupter, and the shielding member is The transmitting part is formed by a notch, the shielding part is formed by an absorbing part, the notch exists between the rotating disk and the reflective photointerrupter, and the notch exists between the rotating disk and the reflective photointerrupter, and The light emitted from the light projecting section of the reflective photo interrupter is detected by the light receiving section of the reflective photo interrupter only when the light reflecting section faces the reflective photo interrupter, and the light detection 2. The position detecting device according to claim 1, wherein the position of the moving object is detected as the specific position.