JPS6240781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a magnetic medium in a magnetic recording device, and more particularly to a method of controlling a magnetic medium in a magnetic tape device used in an information processing system.

〔overview〕

When performing magnetic recording using a magnetic medium, repositioning the magnetic medium (repositioning using reverse movement) and detecting whether the IBG or block on the magnetic medium is facing the read head at the end of the repositioning. The present invention relates to the problem of generating an error signal based on the detection result to assist in accurate positioning of the magnetic medium.

[Prior art and problems to be solved by the invention]

A magnetic tape device used in an information processing system typically has an erase head EH, a write head WH, and a read head RH along the direction of tape movement.
are arranged in this order, information is recorded on the tape block by block, and an interblock gap IBG in which no information is recorded is created before and after the block. Therefore, each block is sandwiched between IBGs. Data written by the write head WH is immediately read by the adjacent read head RH to check whether the data has been correctly recorded on the medium. If an error occurs in recording for some reason, the block in which the error occurred is erased and the block is rewritten.

In the conventional technology, when rewriting, the position on the tape corresponding to the erased block is not used, and the rewriting is performed using a new block beyond that, resulting in poor tape usage efficiency and There is a problem that the recording capacity of the tape decreases.

To solve this problem, simply move the tape in the opposite direction by a length corresponding to the erased block. There is a problem in that it is necessary to accurately position the tape, and measures must also be taken in case the tape is not positioned accurately due to tape slipping or the like.

[Means and actions for solving problems]

In the present invention, an erasing head EH, a writing head WH, and a reading head RH are arranged in that order at predetermined intervals along the moving direction of the magnetic recording medium, and recording of information on the magnetic recording medium is performed using an interface. In a magnetic recording device that performs data in units of information blocks sandwiched between block gaps IBG, when the erase head EH erases the information block B1 and the write head WH rewrites the information block, the magnetic medium is erased from the information block. Information block B1 to be erased by erasing head EH by moving in the opposite direction by a distance corresponding to the sum of the length and the distance between reading head RH and erasing head EH.
Then, the magnetic medium is moved in the forward direction, and during the movement a distance equal to the distance, the information block B1 is erased by the erase head EH, and after the erasure is completed, the information block B1 is erased by the write head WH. To begin rewriting B1, the magnetic medium is read by the read head RH so that, at the end of the erase operation, the read head RH and the previous block of the erased information on the magnetic medium are read. interblock gap
The opposing state of the IBG or the preceding information block B2 is detected, and if the reading head RH is located in the preceding information block B2 at the time of the end of the erasure, the reading head RH is located at the end of the erasure. It is characterized by counting the time until the interblock gap IBG is detected, and outputting an error signal if the result of the counting is longer than the time corresponding to the distance between the read head RH and the write head WH. A method for controlling a magnetic medium in a magnetic recording device is provided.

In the device according to the invention, the erase head EH
When the information block B1 is erased by the write head WH and the information block is rewritten by the write head WH, the magnetic medium is
The erase head EH is moved in the opposite direction by a distance corresponding to the sum of the distances between the information block B1 and the erase head EH, and the erase head EH is positioned at the beginning of the information block B1 to be erased. Thereafter, the magnetic medium is moved in the forward direction, and the erasing head EH erases the information block B1 during the movement by a distance equal to the distance described above, and after the erasing is completed, the writing head WH starts rewriting the information block B1. At the end of the erase operation, the read head RH reads the magnetic medium.
The opposing state of RH and the preceding interblock gap IBG or preceding information block B2 of the erased information block on the magnetic medium is detected. At the end of the erasure, the reading head RH
is located in the preceding information block B2, the reading head is
The time until the RH detects the interblock gap IBG is counted and an error signal is output if the result of the counting is longer than the time corresponding to the distance between the read head RH and the write head WH.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figures 2A, B, C, D, and E show the relationship between tape and heads, where T is the tape, EH is the erase head, WH is the write head, and RH is the read head. It is assumed that the robot moves in the direction of arrow A, or in the opposite direction to arrow A in the opposite direction. FIG. 2A shows that there is an interblock gap G after the information block B2, and then an information block B1. When erasing or rewriting because there is an error in block B1,
After moving the tape in the opposite direction to the position shown in Figure 2B, erase head EH is operated to erase block B1, and when the tape is in the state shown in Figure 2C, write head WH is operated to rewrite. Do this.

In these operations, the amount of tape travel is precisely controlled using tacho pulses, but if there is an abnormality in the tacho pulses themselves or if the tape slips, the write head WH will be unable to use the effective block when rewriting. (For example, B2) may be overwritten. To solve this problem, check the tape stop position using the read head RH, and if the tape does not stop at the specified position, either reposition the tape again or generate an error signal to stop the tape. It is necessary to indicate that the stop position of the vehicle is incorrect.

In one embodiment of the present invention, the read head is located at the stop position of the tape after repositioning.
The part where RH is not a data block (i.e. IBG)
, and raise an error signal when it is not. Since no information is recorded on the IBG, the block portion and the IBG portion on the tape can be distinguished by detecting whether or not information is recorded using a reading head.

FIG. 1 shows a block diagram of the apparatus for the above embodiment. First, assume that the tape is in the state shown in FIG. 2A, and that the tape is now moved in the opposite direction. The AND circuit 11 in Fig. 1 is read.
This is to start a repositioning operation after executing a command and before erasing or writing. One input is connected to the output of the OR circuit 10, and the other input is connected to a signal indicating the read status (MTU RDS). Ru. A signal (ERS) instructing erasure and a signal (WRT) instructing writing are connected to the inputs of the OR circuit 10. The flip-flop 12 for instructing backward movement of the tape (BSP) is set by the output of the AND circuit 11, and thereby a backward drive (R) signal is given to the motor drive circuit 13, so that the motor 14 is activated. By rotating in the opposite direction, the tape is moved in the opposite direction by the capstan 15. At this time, the up-down counter 16 is set as an up-counter by the output of the flip-flop 12.

When the tape moves, a tacho pulse TP is generated according to the amount of movement, and the tacho pulse TP is applied to the up-down counter 16. Up-down counter 16 counts the number of tacho pulses TP, and when the counter overflows, it produces an output at terminal OF, which resets flip-flop 12 and sets another flip-flop 17. At this time, the tape is in the state shown in FIG. 2B.

Now, by resetting flip-flop 12, the reverse movement of the tape is stopped, while by setting flip-flop 17, the erasing operation begins. The up-down counter 16 is set as a down counter by the output of the flip-flop 17, and since the OR circuit 19 generates an output, the tape is driven in the forward direction (F) by the motor drive circuit 13, and current is applied to the erase head EH. The erase operation is performed. At this time, a tacho pulse TP is also generated in accordance with the amount of tape movement, and the contents of the up-down counter 16 are subtracted by one. When the contents of the counter reach zero, terminal ZERO generates an output, which resets flip-flop 17. As a result of resetting the flip-flop 17, the erasing operation of the tape is completed and the state of the tape becomes as shown in FIG. 2C.

If the read head RH is then above the IBG, the IBG detection circuit 20, which is connected to the read head through the demodulation circuit 21, produces an output.

On the other hand, even if the read head RH is above the block, the write head RH
As long as it does not extend to WH (the state shown in Figure 2 D), there will be no actual harm even if you continue writing. However, if you write to a block that spans the write head as shown in Figure 2E, the contents of the block will be destroyed.
In this case, an error signal must be generated.

In the apparatus of FIG. 1, in order to distinguish between the states of FIG. 2D and FIG. 2E, the distance l between the reading head RH and the end of the block is measured, and this distance An error signal is generated in the above cases.

In the device shown in FIG. 1, when the contents of the up-down counter 16 become zero during an erase operation, the AND circuit 40 generates an output, the flip-flop 41 is turned on, and the flip-flop 18 is also turned on. When the flip-flop 18 is turned on, a write operation is performed on the tape. On the other hand, flip-flop 41 remains on until a signal is applied from IBG detection circuit 20 via terminal A, and a counter 42 counts the time during which flip-flop 41 is on.

Here, if the period of the counter clock is t, the tape speed is s, and the allowable distance between the reading head RH and the end of the block is l, then the count value C of the counter that should generate an error signal is C=l/s・t. becomes. That is, if the IBG detection circuit 20 does not generate an output before the content of the counter 42 reaches the above value, the output of the counter 42 turns on the flip-flop 30 and generates an error signal (ERR).

In carrying out the present invention, when the erasing operation is completed, the read head RH is set to the position D in FIG.
When it is above the block as shown in Figure E, the tape can be driven forward to ensure that the read head RH is above the IBG before a write operation is performed. At this time, after the erase operation is completed, while driving the tape in the forward direction, it is checked whether the IBG detection circuit 20 generates an output,
When the generation of the output is detected, the write operation may be started.

〔Effect of the invention〕

According to the present invention, interblock gap detection is used for magnetic medium repositioning, and an error signal is output when there is a position error, so that the magnetic medium can be accurately repositioned without reducing the recording capacity of the magnetic medium. Positioning is performed and repositioning errors can be reliably detected.

Further, according to the present invention, the opposing relationship between the reading head and the information block is detected at the end of repositioning, and even if there is an abnormality in the tacho pulse itself for controlling the amount of tape travel, or if the tape slips, etc. A highly reliable magnetic tape device can be obtained without rewriting on valid blocks when writing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a device to which a method for controlling a magnetic medium in a magnetic recording device as an embodiment of the present invention is applied, and FIGS. 2A to 2E are diagrams illustrating the relationship between a magnetic tape and a head. It is. Explanation of symbols, 12: Flip-flop circuit, 1
3: Motor drive circuit, 14: Motor, 15: Capstan, 16: Up/down counter, 17,
18: Flip-flop circuit, 20: IBG detection circuit, 21: Demodulation circuit, 30: Flip-flop circuit, 41: Flip-flop circuit, 42: Counter, T: Tape, EH: Erase head, WH: Write head, RH: Read head, B1 ,B2,B
3: Information block, G: Interblock gap.

Claims (1)

[Claims] 1. An erase head EH, a write head WH, and a read head RH arranged in that order at predetermined intervals along the moving direction of the magnetic recording medium, and for transmitting information to the magnetic recording medium. In a magnetic recording device in which recording is performed in units of information blocks sandwiched between interblock gaps IBG, when the erase head EH erases the information block B1 and the write head WH rewrites the information block, the magnetic medium is The erase head is moved in the opposite direction by a distance corresponding to the length of the information block plus the distance between the read head RH and the erase head EH.
EH is positioned at the beginning of the information block B1 to be erased, and then the magnetic medium is moved in the forward direction, and the information block B1 is erased by the erase head EH during the movement of a distance equal to the distance, and the erasure is completed. At the end of the erase operation, the read head RH and the erase on the magnetic medium are read by the read head RH to subsequently start rewriting the information block B1 by the write head WH. The interblock gap before the information block
The opposing state of the IBG or the preceding information block B2 is detected, and if the reading head RH is located in the preceding information block B2 at the time of the end of the erasure, the reading head RH is located at the end of the erasure.
It is characterized by counting the time until the interblock gap IBG is detected, and outputting an error signal if the result of the counting is longer than the time corresponding to the distance between the read head RH and the write head WH. A method for controlling a magnetic medium in a magnetic recording device.