JPH0785616A - Head position detection mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] Head position detection for fine tracking in which the reference position of the head can be specified even when driven manually or by external power in a carriage transfer mechanism of a recording / reproducing device that positions a magnetic head on a magnetic disk or the like. Provide a mechanism. The pin gear 1 is rotated by the rotation of the head feed rotary plate 3, and the two pins 1a and 1b are alternately engaged with the U-shaped tooth groove 2b of the cylindrical main gear 2. As a result, the main gear 2 rotates while moving with the characteristic of a sine curve or a cycloid curve, is transmitted to the drive transmission cam 5 via the reduction gear 4a, etc., and the carriage 8 to which the magnetic head is fixed rotates the cam 5. Move according to.
On the other hand, the reference position can be determined by the output of the photo interrupter 12 provided on the inner peripheral portion of the main gear 2. With respect to this reference position, the reproduction output value is judged, and the head position is finely moved to a position where the maximum reproduction output is obtained, so that fine tracking can be performed without using the power source information of the head transfer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carriage transfer mechanism for a magnetic disk device or the like for recording or reproducing, and more specifically to a head position detecting mechanism in the transfer mechanism.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk has been used as a recording medium for computer equipment such as a personal computer, and recently has also been adopted as a recording medium for electronic still cameras and the like. With the miniaturization of each of these magnetic disks, it is required that the magnetic disks as recording media also be miniaturized and have high density recording. Due to the miniaturization of the magnetic disk, the distance between the recording and reproducing tracks becomes small, and the moving mechanism of the magnetic head for recording or reproducing on each track requires highly accurate position control. Therefore, the structure is complicated and tends to be large.

Therefore, conventionally, a mechanism has been proposed in which a carriage is moved and a magnetic head is moved to each track by driving a lead screw using a stepping motor. This method is to perform highly accurate head position control by improving the mechanical accuracy. Therefore, if compatibility is taken into consideration, mechanical precision alone may be insufficient. In such a case, so-called fine tracking must be performed, in which the head position is moved within a required range to obtain a reproduction signal and a just track is obtained based on the reproduction signal level.

[0004]

When performing fine tracking, it is necessary to determine a reference position and move a necessary range from that position. Usually, the phase of the stepping motor is used to determine this reference position. However, when the head is moved manually or by external power, such a method cannot be used and fine tracking cannot be performed. An object of the present invention is to provide a head position detecting mechanism that enables fine tracking even when the head is moved manually or by external power.

[0005]

In order to achieve the above object, a head position detecting mechanism according to the present invention is provided with pins at positions which are point-symmetric with respect to a rotation axis and are rotated manually or by an external power. It has a disk-shaped pin gear and U-shaped tooth grooves at equal intervals so as to alternately engage two pins of the rotating pin gear, and has a periodicity with respect to the rotation of the pin gear at a constant angle. A main member that is rotatably driven in both forward and reverse directions according to the amount of rotation of the pin gear while moving so as to form a continuous curve formed by connecting a part of a sine curve or a cycloid curve; A drive transmission cam for responding to a member and creating a displacement amount for accessing each track, and a magnetic head are fixed, and a part of the magnetic head is pressed against the outer peripheral surface of the drive transmission cam to drive the drive. A carriage transfer mechanism of a magnetic recording / reproducing apparatus comprising a carriage that moves in a radial direction with respect to a track on a concentric circle of the magnetic recording medium according to the rotation of a reaching cam, and detects the position on the pin gear or the main member. Is provided and the reference position of the track is detected to continuously move the minute amount head in both directions with respect to the head reference position to obtain the maximum reproduction output point and perform fine tracking. For example, since the configuration is such that one track is fed for one rotation of the pin gear, the reference position of each track can be determined by determining the fixed position of the pin gear.

[0006]

According to the above structure, the reference position of the head can be determined and fine tracking can be performed even when the head is moved manually or by external power.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a front view and a plan view showing an embodiment of a head position detecting mechanism that enables fine tracking according to the present invention. FIG. 2 is a partially enlarged view of the vicinity of the pin gear in FIG. In each drawing, 1 is a pin gear, 2 is a main gear as a main member, 3 is a head feed rotary plate, 4
a and 4b are reduction gears, 4c is a gear, 5 is a drive transmission cam,
6 is a rotary shaft, 8 is a carriage, 9 is a magnetic head, and 12 is a photo interrupter. The head feed rotary plate 3 has a shape in which flat portions of two large and small cylinders 3a and 3b are superposed on a concentric circle, and a tooth portion 3c is formed on the outer peripheral surface of the smaller cylinder 3b.

The pin gear 1 has a disk shape and is rotatably attached to a chassis (not shown) by a rotary shaft 6. The pin 1 is provided on one of the planes of the pin gear 1 at a point-symmetrical position (near the outer peripheral portion) about the rotary shaft 6.
a and 1b are planted. A tooth portion 1c is formed on the outer peripheral surface of the pin gear 1, and the column 3 of the head feed rotary plate 3 is formed.
It is meshed with the tooth portion 3c on the outer peripheral surface of b. Main gear 2
Has an annular shape and has a U-shaped tooth groove 2b on the inner peripheral surface.
And a tooth portion 2a is formed on the outer peripheral surface thereof. Tooth space 2b
Is the same as the distance between the pins 1a and 1b of the pin gear 1 and meshes with the pins 1a and 1b of the pin gear 1. The main gear 2 is rotatably attached to a chassis (not shown) by a roller portion of a gear retainer (not shown).
A tooth portion 2a on the outer peripheral surface of the main gear 2 is meshed with a reduction gear 4a that is a combination of two spur gears, and the reduction gear 4a is connected to a drive transmission cam 5 via a reduction gear 4b and a gear 4c. . A photo interrupter 12 is provided near the inner peripheral surface of the main gear 2. The position detector is constituted by the photo interrupter 12 and the tooth groove 2b.

The drive transmission cam 5 comprises a spur gear 5a and a cam 5b having an outer peripheral surface formed of a curved surface.
Meshes with the gear 4c. The shape of the cam 5b is a curved surface that moves in one track section of the magnetic recording medium when the pin gear 1 makes a half rotation. The carriage 8 is supported by rollers on a rail provided on a chassis (not shown) so as to be movable within a range indicated by an arrow B. A pin 8a is planted at the tip of the carriage 8, and a spring (not shown) imparts a movement tendency to the left.
Therefore, the pin 8a is pressed against the outer periphery of the cam 5b of the drive transmission cam 5. The magnetic head 9 is adhesively fixed to the middle portion of the carriage 8.

Next, the operation of the mechanism shown in FIG. 1 will be described. In the figure, when the head feed rotary plate 3 is manually rotated, the pin gear 1 is rotated accordingly. When the head feed rotary plate 3 rotates 360 degrees here, the pin gear 1 rotates 180 degrees. This is because the ratio of the number of teeth of the tooth portion 1c and the number of teeth of the tooth portion 3c is 2: 1. When the pin gear 1 rotatably supported by the chassis rotates, the pins 1a and 1b alternate with each other.
The cylindrical main gear 2 rotates by meshing with the character-shaped tooth groove 2b.

FIG. 3 shows the displacement of the main gear 2 and the pin gear 1.
It is a figure showing the relationship of the rotation angle of. The vertical axis represents the displacement Δx,
The rotation angle Δθ is shown on the horizontal axis. When the displacement of the main gear 2 is approximated to a straight line in the enlarged portion of the joint between the pin gear 1 and the main gear 2, the displacement Δx draws a sine curve, and a curve like the solid line in FIG. Strictly speaking, the sine curve of FIG. 3 describes a cycloid curve. As described above, the pin gear 1
Therefore, the displacement of the main gear 2 rotated as shown in FIG.
Reduction gear 4 meshing with teeth 2a on the outer peripheral surface of main gear 2
drive transmission cam 5 that is transmitted to a and is further meshed with gear 4c
Communicate to. The drive transmission cam 5 pushes the pin 8a of the carriage 8 in contact with the curved surface of the cam 5b according to the displacement of the main gear 2.

Therefore, the magnetic head 9 fixed to the carriage 8 is displaced with respect to the rotation angle of the head feed rotary plate 3 while following a locus having characteristics similar to those in FIG. 3 (the vertical and horizontal magnifications are different). . Therefore, the photointerrupter 12 detects the tooth groove 2b of the main gear 2 at a position where the displacement of the magnetic head is minimized. If the rotation angle is corrected by using this position as the head reference position, just tracking can be performed more accurately. In FIG. 1, the position of the magnetic head 9 is the initial position, and by the clockwise rotation of the head feed rotary plate 3, the drive transmission cam 5 rotates counterclockwise, and the magnetic head 9 moves between tracks in FIG. While moving in the same manner as the curved line, it moves in the direction of arrow A and moves to the position 9 '. By moving the magnetic head 9 to the 9'position, for example, tracking from 1 track to 52 tracks of a floppy disk becomes possible.

FIG. 4 is a block diagram showing an embodiment of the circuit of the head position detecting mechanism according to the present invention. The head feed transmission system 16 is a portion including the head feed rotary plate 3, the main gear 2, the gear trains 4 a, 4 b and 4 c, the drive transmission cam 5, and the carriage 8 in FIG. 1. Head position detector 15
Is composed of the photo interrupter 12 and the tooth groove 2b of the main gear 2, and the output of the photo interrupter 12 is input to the arithmetic unit 19. On the other hand, the output of the magnetic head 9 moved by the carriage 8 is connected to the signal processing system, and a part of the output is input to the reproduction output detector 17. The output of the reproduction output detector 17 is stored in the memory 20, and the output of the memory 20 is calculated by the calculator 19. Based on the result, the head feed power unit 18 drives the head feed rotary plate 3.

FIG. 5 is a flow chart for explaining the operation of FIG. According to the track movement command, the head feed power unit 18 drives the head feed transmission system 16 to move the magnetic head 9. Then, the head position detector 15
Detects the reference position, it is determined that the magnetic head has moved to the reference position (S506). Based on this position, the magnetic head is moved to perform fine tracking (S5
01), the reproduction output of the magnetic head 9 is detected (S50).
2). The detection output is stored in the memory unit 20, and the calculation unit 19 determines whether or not the reproduction output is the maximum (S503). When the reproduction output is not the maximum, the head feed driving force unit 18 slightly moves the head position (S504). Then, it is again determined whether the output is maximum (S503). In this way, the loop of S502, S503 and S504 is repeated until the maximum reproduction output is obtained. As a result, when the maximum reproduction output is obtained, the fine tracking is finished and the best reproduction signal is obtained (S505).

FIG. 6 is a block diagram showing another embodiment of the present invention. This embodiment is an example in which a position detector is provided for a pin gear. The pin gear 15 has a pin 15
a and 15b are planted, and a rotating portion 15d having a cutout portion 14 in the outer peripheral portion and a rotating shaft 16 are attached.
5d and the gear part 15c fixed integrally. The photo interrupter 13 is arranged on the outer peripheral portion of the rotating portion 15d. The photo interrupter 13 and the notch 14 constitute a position detector. The other components are the same as in the embodiment of FIG. In this way, even if the position detector is provided on the pin gear side, the reference position can be similarly detected, and fine tracking can be performed. In the above embodiments, the main gear is used as the main member to obtain the rotational movement amount. However, a linear main rack is used as the main member to convert the linear movement into the linear movement, and the structure is to be coupled to the reduction gear train. Is also possible.

[0016]

As described above, according to the present invention, the pin gear in which the pins are planted in the point symmetrical position about the rotation axis and the U-shaped tooth groove at the pitch between the pins are provided to rotate. A pin member of a pin gear is engaged alternately, and a main member that displaces while moving with characteristics such as a sine curve, and a drive transmission cam that responds to this main member and creates a displacement amount for accessing each track And a carriage to which the magnetic head is fixed and which moves according to the movement of the outer peripheral surface of the cam, and which is configured to detect the reference position of the track by providing a position detector on the pin gear or the main member. Has been done. Therefore, even when the pin gear is rotated manually or by external power, fine tracking can be performed by moving the minute amount head continuously in both directions with respect to the head reference position and obtaining the maximum reproduction output point.

[Brief description of drawings]

FIG. 1 is a front view and a plan view showing an embodiment of a head position detection mechanism that enables fine tracking according to the present invention.

FIG. 2 is a partially enlarged view of the vicinity of the pin gear in FIG.

3 is a diagram showing a characteristic of displacement of a magnetic head by the mechanism of FIG.

FIG. 4 is a block diagram showing an embodiment of a circuit of a head position detecting mechanism according to the present invention.

FIG. 5 is a flowchart for explaining the operation of FIG.

FIG. 6 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 1 pin gear 2 main gear 3 head feed rotary plate 4a, 4b reduction gear 4c gear 5 drive transmission cam 6 rotary shaft 8 carriage 9 magnetic head 12,13 photo interrupter 14 notch

Claims (1)

[Claims] 1. A disk-shaped pin gear, which is provided with pins at positions symmetric with respect to a rotation axis and is rotated manually or by an external power, and two pins of the rotating pin gear are alternately engaged with each other. U-shaped tooth grooves at equal intervals so as to match, so as to form a continuous curve having a periodicity with respect to the rotation of the pin gear at a constant angle and connecting a part of a sine curve or a cycloid curve. Main member driven in accordance with the rotation amount of the pin gear so as to be rotatable in both forward and reverse directions while performing various movements, and a drive for responding to the main member and generating a displacement amount for accessing each track. The transmission cam and the magnetic head are fixed, and a part of the magnetic head is pressed against the outer peripheral surface of the drive transmission cam, and radiates to a track on a concentric circle of the magnetic recording medium according to the rotation of the drive transmission cam. A carriage transfer mechanism of a magnetic recording / reproducing apparatus comprising a carriage that moves in a direction, wherein a position detector is provided on the pin gear or the main member, and a head reference position is detected by detecting a track reference position. A head position detection mechanism characterized by finely tracking a reproduction output maximum point by moving a small amount of head continuously in both directions.