JP3478045B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for recording and reproducing magnetic data on a magnetic medium. 2. Description of the Related Art Some magnetic recording / reproducing apparatuses of this kind record magnetic data on a magnetic tape attached to a passbook, a cut sheet, or the like using a magnetic head, or write data on the magnetic tape. There are devices for reading recorded magnetic data. FIG. 4 is a diagram showing a state of recording and reproducing of magnetic data by such a magnetic recording and reproducing apparatus.
Denotes a magnetic head, 2 denotes a cut sheet, and 2A denotes a magnetic tape attached to the cut sheet 2. In the magnetic recording / reproducing apparatus, when the cut sheet 2 is set at a predetermined position, the magnetic head 1 at the home position is moved to a predetermined position of the cut sheet 2, and
The magnetic data is recorded on the magnetic tape 2A attached to the magnetic tape 2A, or the magnetic data is read from the magnetic tape 2A and reproduced. FIG. 5 is a time chart showing a state of reproducing magnetic data by such a magnetic recording / reproducing apparatus. Here, FIG. 5A is a time chart of a pulse signal called an FG signal obtained from rotation of a motor (not shown) for moving the magnetic head 1, and FIG. 5B is a standby state of the magnetic head 1. H placed near home position
This is a signal from an OP sensor (not shown), and is a HOP signal output when the magnetic head 1 passes through the home position and moves toward the magnetic tape 2A. Also,
FIG. 5C shows a reproduced signal of magnetic data reproduced by the magnetic head 1, and FIG. 5D shows a demodulated signal obtained by demodulating the reproduced signal by a demodulation circuit (not shown), which is a signal called an F2F signal. is there. Here, F2F demodulated by the demodulation circuit is used.
The signal includes an F signal whose level changes once within a predetermined time,
2F signal whose level changes twice within a predetermined time. That is, the waveform of the portion indicated by the symbol D2 in FIG. 5D is the F signal, and indicates the data value "0". FIG.
The waveform of the portion indicated by the symbol D3 in (d) is a 2F signal, which indicates a data value "1". Normally, when magnetic data is recorded on a magnetic medium such as a magnetic tape, first several tens of bits of an F signal are sequentially recorded from the head area of the magnetic medium, and then a 2F signal indicating a start bit of the data is recorded. And data bits consisting of 2F signals are recorded. When the magnetic head 1 at the home position moves to the head area of the magnetic tape 2A attached to the cut sheet 2 to record data, the magnetic head 1 moved from the home position. When the magnetic head 1 is pushed back due to the collision between the head 1 and the magnetic tape 2A, and an F signal (data "0") is recorded by the magnetic head 1 at this time, an erroneous signal other than the F signal is recorded in the head area of the magnetic tape 2A. Data is recorded. Therefore, when such data on the magnetic tape 2A is reproduced, the reproduced data in the head area has a waveform as shown by the part C1 in FIG. 5C, and 2F from the head area where the F signal is originally reproduced. A signal having a shorter time than the signal is reproduced. As a result, when the reproduced signal is demodulated, it is output as a demodulated signal as shown by a portion D1 in FIG. Since such a demodulated signal does not correspond to either the F signal or the 2F signal, the control unit determines that the demodulated signal is a demodulation error, so that there is a problem that subsequent demodulation of magnetic data becomes impossible. Accordingly, an object of the present invention is to prevent demodulation errors by accurately demodulating recording data on a magnetic medium such as a magnetic tape in which an error signal is recorded in a leading area portion. [0007] In order to solve the above-mentioned problems, the present invention comprises a magnetic head, records magnetic data on a magnetic medium such as a magnetic tape, and moves the magnetic head to a home position. A magnetic recording / reproducing apparatus for reproducing magnetic data sequentially from a head area of a magnetic medium by moving from a head position of a magnetic head; and detecting means for detecting passage of a magnetic head at a home position. Counting means for counting the number, after the detection output of the detecting means, the count value counted by the counting means is set to a predetermined distance between the detecting means and the head area of the magnetic medium and the recording of defective data in the head area when it becomes a value that includes a range
A judging means for the magnetic head and outputs a signal indicating that it has passed the first part in, the signal output from the determination means
Demodulating means for demodulating a reproduction signal of the magnetic head based on the demodulated signal. Therefore, since the magnetic data of the head area and subsequent areas are demodulated without demodulating the magnetic data of the head area of the magnetic medium, it is possible to accurately demodulate the recording data of the magnetic medium in which an error signal is recorded in the head area. As a result, a demodulation error can be prevented. In addition, it is possible to accurately determine that the magnetic head has passed the head area of the magnetic medium and demodulate the recording data after the error signal. Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of a magnetic recording / reproducing apparatus according to the present invention. In the drawing, 1 is a magnetic head, 2 is a cut, 2A is a magnetic tape attached to the cut 2, 3 is a motor for moving the magnetic head 1, 4 is a rotation of the motor 3 and the FG signal a is detected. Output encoder, HO arranged at home position of magnetic head 1
P sensor. Reference numeral 10 denotes a control unit, 11 denotes a counter, 12 denotes a flip-flop circuit (hereinafter, referred to as F / F circuit), 13 denotes an AND circuit (logical product circuit), and 14 denotes a demodulation circuit. In FIG. 1, an FG signal a from the encoder 4 based on a rotation signal of a motor 3 for moving the magnetic head 1 is supplied to a clock terminal CLK of the counter 11, and a clear terminal CLR of the counter 11 is supplied to the clock terminal CLK of the counter 11. HOP from the HOP sensor 5 indicating that the magnetic head 1 has passed the home position and has moved in the direction of the magnetic tape 2A.
A signal b is provided. The output signal e from the counter 11 is supplied to the clock terminal CLK of the F / F circuit 12, and the control unit 10 is connected to the clear terminal CLR of the F / F circuit 12.
From the start signal c. An output signal f of the F / F circuit 12 is supplied to one input terminal of the AND circuit 13, and a reproduction signal d from the magnetic head 1 is supplied to the other input terminal.
In the demodulation circuit 14, the start signal c is supplied to the input terminal S
When the signal is input to the TART, the signal output from the AND circuit 13 and input to the input terminal F2F is demodulated, and the output terminal O
The UT outputs the F2F signal h to the control unit 10. Here, of the F2F signals output from the demodulation circuit 14,
The signal is a signal whose level changes once within a certain time,
The 2F signal is a signal whose level changes twice within a certain time. Next, the general operation of the present apparatus will be described with reference to FIG. When the cut sheet 3 to which the magnetic tape 2A is attached is set at a predetermined position, the control unit 10 drives the motor 3 to move the magnetic head 1 at the home position to the head recording area of the magnetic tape 2A. The control unit 10
Outputs a start signal c to the F / F circuit 12 and the demodulation circuit 14 at this time to clear the F / F circuit 12 and prepare the demodulation circuit 14 to demodulate the reproduction signal of the magnetic tape 2A. When the magnetic head 1 moves from the home position in the direction of the magnetic tape 2A, this moves to the HOP sensor 5.
, And is supplied to the counter 11 as the HOP signal b, and the counter 11 is cleared. Counter 11
Counts the number of pulses of the FG signal a after being cleared by the HOP signal b. When the count value reaches a predetermined value, an output signal e is output to the F / F circuit 12. Then, F / F circuit 12 outputs an “H” level signal f from output terminal Q to one input terminal of AND circuit 13. Here, before the time when the output signal of the F / F circuit 12 becomes "H" level (that is, the time when the count number of the FG signal a in the counter 11 becomes a predetermined value), the magnetic head 1 Is in contact with the magnetic tape 2A, the reproduced signal d from the magnetic head 1
Is input to the other input terminal. Therefore, in the AND circuit 13, the reproduction signal f of the magnetic head 1 after the signal f of the F / F circuit 12 becomes "H" level is demodulated by the demodulation circuit 1.
Output to 4. Upon receiving the reproduced signal d, the demodulation circuit 14 demodulates the signal and outputs an F2F signal h to the control unit 10. When the magnetic head 1 at the home position moves to a predetermined head area of the magnetic tape 2A to record data, the magnetic head 1 that has moved from the home position and the magnetic tape 2A collide with each other.
When the magnetic data is recorded by the magnetic head 1 at this time, erroneous data may be recorded in the head recording area of the magnetic tape 2A. Here, demodulation of such erroneous data on the magnetic tape 2A causes a demodulation error. Therefore, in the present embodiment, the counter 11 is provided, and the demodulation is waited for the count time by the counter 11 so as to wait for the demodulation. Erroneous data is not demodulated. When recording magnetic data on a magnetic medium,
In this apparatus, first, several tens of bits of the F signal are sequentially recorded from the head area of the magnetic medium, and then 2 bits indicating a data start bit
The F signal is recorded, and data bits composed of the F signal and the 2F signal are recorded following the start bit. Therefore, when reproducing data from such a magnetic medium, there is no problem even if the data in the head area is discarded. That is,
When the magnetic head 1 and the magnetic tape 2A collide, the magnetic head 1
Is a signal of several bits (the F signal out of the F signal and the 2F signal) recorded in the head area of the magnetic tape 2A, and the signal in the head area is read and discarded during data reproduction. Thus, even if demodulation is started from data recorded in the subsequent area, no problem occurs. Therefore, in the present apparatus, the defective data in the head area recorded at the time of collision between the magnetic head 1 and the magnetic tape 2A is not demodulated. Here, the predetermined count value of the FG signal a counted by the counter 11 is, in the present embodiment,
It is determined as follows. That is, in FIG. 2, the moving distance from when the magnetic head 1 passes through the position of the HOP sensor 3 until it contacts the magnetic tape 2A is 6 mm, and the moving distance of the magnetic head 1 for one pulse of the FG signal a is 0. 3
When the length is 14 mm, the number of pulses of the FG signal a until the magnetic head 1 contacts the magnetic tape 2A is about 20 pulses (6 / 0.314). Here, taking into account that the tolerance of the set position of the magnetic tape 2A (that is, the set position of the cut sheet 2) is ± 2 mm, and that the magnetic tape 2A is to be Considering that the range of the defective recording data recorded in the head area is 2 mm, the count pulse number of the FG signal a is 40 pulses ((6 + 4 + 2) /0.3
14). Next, the operation of the main part of the present invention will be described in more detail with reference to the time chart of FIG. When the motor 3 is rotated to move the magnetic head 1 from the home position in the direction of the magnetic tape 2A, an FG signal a corresponding to the rotation speed of the motor as shown in FIG. Is done. Here, when the magnetic head 1 passes the home position, the HOP sensor 5 outputs
The “H” level HO at the timing shown at (b)
The P signal b is output and provided to the counter 11. In the counter 11, the HOP signal b becomes "H".
The number of pulses of the FG signal a is counted from the point in time when the level is reached. Then, as described above, this count value is “4”.
When the signal e becomes "0", an "H" level signal e is output to the F / F circuit 12, so that the F / F circuit 12 inputs the AND signal to the AND circuit 13 as shown in FIG. An H-level signal f is output. As a result, the AND circuit 13 outputs
Of the reproduced signal d shown in (c), the reproduced signal d after the time is output to the demodulation circuit 14. Therefore, the reproduced signal after the time is input and demodulated in the demodulation circuit 14, and the F2F signal shown in FIG. h to the control unit 10. That is, in the demodulation circuit 14, of the reproduction signal d in FIG. 3C, the reproduction signal before the time point (that is, the defective data recorded in the head area when the magnetic head 1 and the magnetic tape 2A collide) Since no demodulation is performed, only a normal reproduction signal after the time point can be demodulated and output to the control unit 10. Therefore, the control unit 10 accurately extracts the F signal and 2F from the demodulated signal.
Signals can be accurately identified. Then, the control unit 10 recognizes the 2F signal indicated by the symbol E2 following the F signal indicated by the symbol E1 in the F2F signal h shown in FIG. The following F2F signal is taken in as data bits. As described above, according to the present invention, when reproducing magnetic data on a magnetic medium, the magnetic head moves from the home position and reproduces the magnetic data sequentially from the head area of the magnetic medium. in the magnetic recording and reproducing apparatus, a magnetic
Detecting means for detecting passage of the head through the home position
And the pulse signal output for each predetermined moving distance of the magnetic head.
Counting means for counting the number of signals, and determining means.When the passage of the home position of the magnetic head is detected by the detecting means, the determining means determines whether or not the magnetic head has passed the head area of the magnetic medium. After the detection output of the detection means
The count value counted by the counting means is used for a preset detection.
Between the output means and the head area of the magnetic medium and the head area
When the value including the recording range of the defective data is determined , and the determination means determines the passage of the head area of the magnetic head, the reproduction signal of the magnetic head is demodulated. Since the magnetic data after the head area is demodulated without being demodulated, it is possible to accurately demodulate the recording data of the magnetic medium in which an error signal is recorded in the head area, thereby preventing a demodulation error. Further, it demodulates the recorded data after error signal to determine accurately the magnetic head has passed the first part of the magnetic medium.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a main configuration of a magnetic recording / reproducing apparatus according to the present invention. FIG. 2 is a diagram showing a data reproduction state of a magnetic medium by a magnetic head in the device. FIG. 3 is a time chart showing the operation of each unit of the above device. FIG. 4 is a diagram showing a recording / reproducing situation of magnetic data by a conventional device. FIG. 5 is a time chart showing an operation of the conventional device at the time of data reproduction. [Description of Signs] 1 ... magnetic head, 2 ... single sheet, 2A ... magnetic tape, 3 ... motor, 4 ... encoder, 5 ... HOP sensor, 10 ... control unit, 11 ... counter, 12 ... F / F circuit, 13 ... AND circuit, 14 ... demodulation circuit.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 5/09

Claims (1)

(57) [Claim 1] A magnetic head is provided, magnetic data is recorded on a magnetic medium including a magnetic tape, and the magnetic head moves from a home position to move to a head area of the magnetic medium. A magnetic recording / reproducing apparatus that sequentially reproduces magnetic data from a magnetic head; detecting means for detecting passage of the magnetic head at a home position; and counting means for counting the number of pulse signals output for each predetermined moving distance of the magnetic head. After the detection output of the detecting means, the count value counted by the counting means includes a preset distance between the detecting means and a head area of the magnetic medium and a recording range of defective data in the head area. a determining means for output power of the signal indicating that the magnetic head when it becomes the value has passed the pre <br/> SL head area, based on the signal output from the determination means Magnetic recording and reproducing apparatus characterized by comprising a demodulation means for demodulating a reproduced signal of the magnetic head are.