JPH0675343B2 - Magnetic sheet reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic sheet reproducing apparatus for reproducing a signal recorded on a rotating magnetic sheet.

2. Description of the Related Art In recent years, high density recording has been pursued in magnetic sheet devices. In this case, tracking during reproduction is indispensable. As a method of this tracking, a head moving means that can move at a step pitch sufficiently smaller than the track pitch by using a stepping motor or the like is configured, and the head is sequentially moved at the step pitch with respect to the recorded track for reproduction. A method of moving the head to a position where the output is maximum is used, but since the head stop position by the head moving means usually has some hysteresis depending on the moving direction, reproduction is performed to remove this hysteresis. A method is often used in which the head movement direction when detecting the position where the output is maximum and the head movement direction when moving the head to the position where the reproduction output selected by detection after that is the same direction are aligned. ing.

However, in the above-mentioned configuration, when the tracking error is made smaller, the step pitch of the head moving means must be made finer, so that when the head is moved to another track. There are problems that the number of steps increases correspondingly, the moving speed becomes slow, and the structure for making the step pitch fine becomes complicated.

In view of the above problems, it is an object of the present invention to provide an inexpensive magnetic sheet reproducing apparatus that enables good tracking without slowing the speed at which the head moves to another track and has a simple structure.

Means for Solving the Problems In order to solve the above-mentioned problems, a magnetic sheet reproducing apparatus of the present invention is a head moving device for moving a magnetic head in a radial direction of a rotating magnetic sheet at a step pitch sufficiently smaller than a track pitch. Means and a driving means for driving the head moving means, and the reproducing output at each head position by driving the head moving means in the first radial direction by the driving means, and the first The reproduction output at each head position by driving in the second direction, which is the opposite direction to the direction, is compared, and the position of the magnetic head is controlled to the position where the output is maximum.

Operation The present invention makes it possible to perform tracking at a finer pitch than the original step pitch of the head moving means by positively utilizing the difference in head position depending on the moving direction of the head moving means, that is, hysteresis, with the above-described configuration. , It is possible to suppress the deterioration of the reproduction output due to the tracking error.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a diagram showing hysteresis, and 100 is a track to be reproduced now. 101 to 104 are head positions for each pitch when the head 2 is stepwise moved in the A direction, and 105 and 106 are head positions when the head 2 is moved in the B direction opposite to the A direction. (Note that although the positions are shifted in the direction perpendicular to the A and B directions, the positions are originally the same, but they are difficult to see if they are drawn as they are. Therefore, the drawing is 102. Although 106, 103 and 105 have the same position command from the control circuit 4, they have different positions due to the different moving directions of the moving means 3. this
The difference between 102 and 106 and the difference between 103 and 105 are hysteresis.

FIG. 1 is a block diagram showing an embodiment of the magnetic sheet reproducing apparatus of the present invention. Circular tracks are formed on the magnetic sheet 1, and the position of a head 2 for reproducing a signal is controlled by a moving means 3 and a control circuit 4 which are movable in a radial direction at a step pitch sufficiently smaller than the track pitch. The output of the head 2 is output from the reproduction amplifier 5 as a reproduction output via the changeover switch 6 and the signal processing circuit 7.

Second Embodiment of the First Embodiment of Tracking Control
A description will be given according to the flowchart in the figure.

First, the moving means 3 is operated by the control circuit 4 to move the head 2 to a position on the outer peripheral side of several steps of the track position on the magnetic sheet 1 to be reproduced, and the output of the reproducing amplifier 5 at this position is switched by the control circuit 4 to the switch 6 Is operated, and is input to the memory 9a together with the head position. Further, the control circuit 4 operates the moving means 3 to move the head 2 stepwise in the inner circumferential direction by one pitch, and the output value of the reproducing amplifier 5 at that position is compared with the output value input to the memory 9a by the comparison circuit 8.
If it is larger, the head position and output value are input to the memory 9a, and the moving means 3 is operated by the control circuit 4 to move the head 2 stepwise to the inner circumference side by one pitch, and the reproducing amplifier at that position is reproduced. Until the output value of 5 becomes smaller than the output value input to the memory 9a, the current head position and output value are input to the memory 9a, and the movement of the head 2 is repeated.

Then, when the position of the head 2 at which the output of the reproducing amplifier 5 is maximized when the head 2 is moved in the inner peripheral direction and the output value of the reproducing amplifier 5 are input to the memory 9a, the moving means 3 is moved by the control circuit 4. The head 2 is operated in the direction opposite to the above, that is, in the direction in which the head 2 moves in the outer peripheral direction, and the head 2 is step-moved to the outer peripheral side by one pitch. Then, the head stops at a position slightly deviated from the position stopped two times before due to the hysteresis described above. The output value of the reproduction amplifier 5 at that position is compared with the memory 9a by the comparison circuit 8, and if it is larger, the current head position is input to the memory 9a and the tracking is completed. However, if the current output value is smaller, if the head 2 is stepwise moved further toward the outer circumference side by one pitch, the head stops at a position slightly offset by hysteresis from the position stopped two times before two times. And the comparison circuit 8 for comparison. At this time, if the current output value is larger, the current head position is input to the memory 9a, and the tracking ends. On the contrary, if the reproduction output at this time is smaller, the head 2 is moved to the head position previously input to the memory 9a, that is, the position moved to the inner circumference side by one pitch from the present, and the tracking ends. In this case, the moving direction of the head is the same as that at the time of detection input to the memory 9a, and the head stops at the same position as at the time of detection.

When the tracking is completed, the control circuit 4 actuates the switch 6 to guide the signal from the reproduction amplifier 5 to the signal processing circuit 7 and outputs it as a reproduction output.

As described above, it is almost equivalent to tracking at a pitch of about 1/2 of the head feed pitch, good tracking is possible, and the head feed pitch itself is the same as before, so other tracks There is no delay in travel time to. Further, the tracking method of the first embodiment can be realized without increasing the number of detection operations in tracking.

Next, a second embodiment of tracking control will be described with reference to the flowchart of FIG.

First, the moving means 3 is operated by the control circuit 4 to move the head 2 to a position on the outer peripheral side of several steps of the track position on the magnetic sheet 1 to be reproduced, and the output of the reproducing amplifier 5 at this position is switched by the control circuit 4 to the switch 6. It is operated and input to the memory 9a together with the head position. Further, the control circuit 4 operates the moving means 3 to move the head 2 stepwise in the inner circumferential direction by one pitch, and the output value of the reproduction amplifier 5 at that position is compared with the output value input to the memory 9a by the comparison circuit 8. If it is larger, the head position and output value at that time are input to the memory 9a, the moving means 3 is further operated by the control circuit 4, and the head 2 is stepwise moved to the inner circumference side by one pitch, and the reproducing amplifier at that position is reproduced. Input of the current head position and output value to the memory 9a and movement of the head 2 are repeated until the output value of 5 becomes smaller than the output value input to the memory 9a.

Then, when the position of the head 2 at which the output of the reproducing amplifier 5 is maximized when the head 2 is moved in the inner circumferential direction and the output value of the reproducing amplifier 5 are completely input to the memory 9a, the moving means 3 is moved by the control circuit 4. The head 2 is operated in the direction opposite to the above, that is, in the direction in which the head 2 moves in the outer peripheral direction, and the head 2 is moved stepwise to the outer peripheral side by one pitch. Then, the head stops at a position slightly deviated from the position stopped two times before due to the hysteresis described above. When the output value of the reproducing amplifier 5 at that position is input to the memory 9b and the same operation as described above is performed, the head 2 is moved in the outer peripheral direction, that is, in the inner peripheral direction described above. The position of the head 2 and the output value of the reproduction amplifier 5 where the output value of the reproduction amplifier 5 becomes the maximum when the head position is displaced by the time and the hysteresis amount are input to the memory 9b.

Next, the output values of the memories 9a and 9b are compared by the comparison circuit 8, and the control circuit 4 operates the moving means 3 in the same direction as the detection at the larger head position to complete the tracking.

As described above, tracking is performed at a pitch that is finer than the head feed pitch, and good tracking is possible, and since the head feed pitch itself is the same as before, the movement time to other tracks is slow. It will never happen. Further, according to the first embodiment, when there is looseness in the moving means 3, the head touch, azimuth, etc. change in the head feeding direction, and the head is moved in the direction in which the reproduction output is relatively reversed, that is, in the outer peripheral side. If 2 becomes large when moving, erroneous tracking may be performed.
According to the embodiment described above, such erroneous tracking is not performed.

When the tracking is completed, the control circuit 4 actuates the switch 6 to guide the signal from the reproduction amplifier 5 to the signal processing circuit 7 and outputs it as a reproduction output.

In the first and second embodiments, the head 2 is first moved to the outer peripheral side of the track position to be reproduced, first moved in the inner peripheral direction and then stepped in the outer peripheral direction to perform tracking. Needless to say, the tracking may be performed by first moving the head 2 to the inner circumference side of the track position to be reproduced, and then stepwise moving to the outer circumference side and then to the inner circumference side.

Although not shown in the flow chart, all of the reproduction output at each position where the head 2 is stepwise moved to the inner circumference side and the reproduction output at each position where the head 2 is stepwise moved to the outer circumference side are stored and compared. It goes without saying that tracking may be performed in which the position of the head 2 is controlled to a position where the output becomes maximum.

EFFECTS OF THE INVENTION As described above, according to the present invention, hysteresis can be positively and effectively utilized, finer tracking than the step pitch of the head moving means can be performed, and reduction in reproduction output due to tracking error can be prevented. Excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic sheet reproducing apparatus of the present invention, FIG. 2 is a flowchart showing tracking control of the first embodiment of the apparatus, and FIG.
FIG. 4 is a flow chart showing the tracking control of this embodiment, and FIG. 4 is an explanatory diagram of the hysteresis characteristic of the head moving means. 1 ... Magnetic sheet, 2 ... Head, 3 ... Moving means, 4
...... Control circuit, 8 ... Comparison circuit, 9 ... Memory.

Claims (1)

[Claims] 1. A magnetic sheet reproducing apparatus for reproducing a signal recorded on a rotating magnetic sheet using a head, comprising:
Head moving means for moving the head so that the head can be moved bidirectionally in the radial direction of rotation of the magnetic sheet at a step pitch sufficiently smaller than a track pitch; and a driving means for driving the head moving means, Reproduction output at each head position by driving the head moving means in the first radial direction by driving means and each by driving in the second direction opposite to the first direction. A magnetic sheet reproducing apparatus characterized in that reproduction outputs at head positions are compared with each other and the head is moved to a position where the reproduction output is maximized.