JPH03105753A - Tape end detection method in magnetic tape device - Google Patents

Abstract

PURPOSE:To detect a tape end without providing a special play to a threader mechanism by detecting a point of time with a drive direction detection means when one reel driven in the winding direction is reversed from the winding direction into the supply direction and taking the reversed point of time as the tape end. CONSTITUTION:A winding side reel B is driven and other supplying reel A is driven simultaneously with a large torque than that for the reel B, a magnetic tape is supplied, and the supplying other reel A reaches the winding mode of the magnetic tape 2 along with the direction so far when all the magnetic tape 24 is supplied out and then the winding reel B is reversed from the winding direction into the supply direction. Then the revising time of the direction of rotation is detected by a direction detection means 4 and the detected point of time is used as the tape end. Then the tape end is detected without provision of special play to the threader mechanism.

Description

[Detailed Description of the Invention] [Summary] In particular, it relates to a tape end detection method in a reel-to-reel direct transfer type magnetic tape device that directly transfers magnetic tape with a reel motor. In a tape end detection method in a magnetic tape device, a rotation direction detection means for detecting the rotation direction of the one reel is provided, and the one reel is wound. At the same time, the other reel is rotationally driven in the feeding direction with a torque greater than that of the one reel, and the rotation direction of the one reel is reversed from the winding direction to the feeding direction by the rotational direction detection means. The point in time when the tape shifts is detected and the point at which the shift is reversed is determined as the end of the tape.

[Industrial Application Field] The present invention particularly relates to a tape end detection method in a reel-to-reel direct transfer type magnetic tape device in which a magnetic tape is directly transferred by a reel motor.

[Prior Art] FIG. 4 is an explanatory diagram of a threader mechanism in a general reel-to-reel direct transfer type magnetic tape device, and (a) shows a state in which a magnetic tape is set by tape loading. (b) shows the threader arm and the league block at the tip of the magnetic tape. Loading the magnetic tape 52 from the cartridge 5l is as follows: (1) First, set the threader arm 53 at the position of the first threader position detection sensor 54, and attach the threader pin at the end of the threader arm 53 to the league block 55 at the end of the magnetic tape 52. 56 is engaged.

(2) Next, while rotating the threader arm 53 and pulling out the magnetic tape 52 from the cartridge 5l, the league block 55 is moved along the trajectory indicated by the dotted line in the figure, and the threader arm 53 is rotated to the position of the threader position detection sensor 57. Let. As a result, the leader block 55 is inserted into the groove of one reel A, and the magnetic tape 52 is placed in the set state.

(3) Then, wind up a predetermined amount of the magnetic tape 52 on reel A, and set the position to BO T (Beginni
After that, the recording position on the magnetic tape 52 is accessed by servo control of the reel motors that drive the reel A and the reel B of the cartridge 5l.

On the other hand, the conventional magnetic tape 52 is replaced by a cartridge 51.
The unloading process for storage was performed as follows.

(1) [When the tape 52 is rewound to the BOT position by servo control, the servo control is released and the reel B
is driven in the winding direction at a low constant speed, and the magnetic tape 52 is wound onto the reel B.

(2) When the magnetic tape 52 is completely fed out on reel A, the threader arm 53 receives a force in the direction of being pulled out from the groove of reel 8, and moves by the amount of play it has in the rotational direction. At this time, the threader position detection sensor 57 turns from on to off, recognizes this point as the end of the tape, and detects a state in which the magnetic tape 52 in reel A is not wound.

(3) When the tape end is detected, the threader arm 53 is driven to rotate in a trajectory opposite to that during loading, is returned to the position of the threader position detection sensor 54, and the leader block 55 is housed in the cartridge 51. At this time, the reel B is driven in the winding direction with a low torque that does not cause the magnetic tape 52 to become loose.

As described above, conventional tape end detection has been accomplished by providing the threader arm 53 with a predetermined amount of play and using the movement due to the play to turn the threader position detection sensor 57 from on to off.

[Problems to be Solved by the Invention] However, in the conventional art, since the threader arm 53 has a special play, the movement of the threader arm 53 during loading/unloading of the magnetic tape 52 is unstable, and the movement is accompanied by vibration. This not only poses a risk of the league block 55 coming off the threader pin 56, but also leads to loosening of the mechanism due to vibration, which poses a problem in terms of reliability.

The present invention was created in view of these problems, and
It is an object of the present invention to provide a method for detecting a tape end in a magnetic tape device, which is capable of detecting a tape end without giving a special play to a threader mechanism and improving reliability.

[Means for Solving the Problems] Means in the present invention for achieving the above object is a method for detecting a tape end in a magnetic tape device, comprising: a rotation direction detection means for detecting the rotation direction of the one reel; The one reel is rotationally driven in the take-up direction, and at the same time, the other reel is rotationally driven in the pay-out direction with a torque greater than that of the one reel, and the rotation of the one reel is controlled by the rotation direction detecting means. This method is based on a tape end detection method in a magnetic tape device, which is characterized by detecting the point in time when the tape reversals from the taking direction to the feeding direction, and determining the point at which the reversal occurs as the tape end. [Function] In the present invention, one reel on the winding side is driven to rotate, and the other reel on the feeding side is driven to rotate with a somewhat larger torque to feed out the magnetic tape. When the magnetic tape is completely unwound, the magnetic tape is wound up by continuing its rotation, and as a result, the rotation of the reel on the take-up side is reversed from the winding direction to the unwinding direction, and when the rotation direction is reversed, is detected by the rotation direction detection means, and the point at which this detection is detected is defined as the tape end. [Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of the main parts of a control system in a magnetic tape device of direct transfer type between reels, which is an embodiment of the present invention. Although not shown here, the magnetic tape device shown in the figure is equipped with a threader mechanism as shown in FIG. Sometimes the magnetic tape is unloaded and then stored in the cartridge.

In FIG. 1, reference numeral 1 denotes a control circuit that controls the entire apparatus, and controls the threader mechanism when loading and unloading the magnetic tape 2, and controls the rotation of reel A and reel B. The rotation control of reel A and reel B is as follows:
Each DC (not shown) is connected via the drive circuits 3a and 3b.
This is done by driving a servo motor, and its rotation speed is linearly controlled. That is, the running of the magnetic tape 2 during access is servo-controlled so that the tape tension is always constant, and during loading and unloading, it is controlled with different settings such as low speed and low torque. Reference numeral 4 denotes a rotational direction detecting means, which detects the rotational direction of reel B using a two-phase tachometer generator 4a that generates 500 slit pulses in one revolution of the servo motor of reel B, and two-phase pulses output from the tachometer generator 4a. It consists of a direction detection circuit 4b which detects the direction and outputs it to the control circuit l. The tacho generator 4a is conventionally provided to obtain the rotational speed of the reel B, and its output A-phase. The B-phase pulse is shown in Figure 2 (C). As shown in (d), the pulses have a phase difference of 90 degrees, and their lead and lag are reversed depending on the direction of rotation. The unloading control of the Wi control circuit 1 and the resulting operations of the reels A and B in this embodiment will be explained below with reference to the timing chart of FIG. 2. (1) When the read/write operation for the magnetic tape 2 is completed, the control circuit 1 rewinds the magnetic tape 2 to the BOT position and stops the servo control.

(2) The drive circuit 3b drives the servomotor of reel B with a low constant current in the direction of winding the magnetic tape 2 (second
Diagram a). Driving with this low constant current results in low torque rotation to the extent that the magnetic tape 2 does not become loose.

(3) The drive circuit 3a drives the servo motor of reel 8 with a low constant voltage in the direction in which the magnetic tape 2 is fed out (second
Figure b). The drive by this low constant voltage rotates at a low speed with a larger torque than by the low constant current, and by this drive, the magnetic tape 2 is unwound from reel A, and in reel B, the drive torque (2) causes the magnetic tape 2 to rotate clockwise. The magnetic tape 2 is rotated to take up the magnetic tape 2.

(4> When all of the magnetic tape 2 is fed out from reel A, reel A continues to rotate, resulting in an operation to wind up the magnetic tape 2 (reverse winding). As a result, since the torque on reel B is small, the clockwise The rotation is switched to counterclockwise rotation in which the magnetic tape 2 is fed out.

(5) At this time, the output of the tachogenerator 4a has the A phase and B phase reversed, as shown in FIG. 2 (c, d).
As a result, the direction detection circuit outputs a signal (FIG. 2e) to the control circuit 1 indicating that the rotation has been switched to the counterclockwise direction.

(6) When the direction detection circuit 4b detects the reversal of the rotational direction of the reel B, the control circuit l recognizes that the magnetic tape 2 is not being wound on the reel A, that is, is at the end of the tape, and The rotation is stopped, and then the unthreading operation by the threader mechanism is started as in the conventional method, and the same control as in the conventional method is performed thereafter.

In this way, in this embodiment, when unloading the magnetic tape 2 into the cartridge, the reel A, which is the side that feeds out the magnetic tape 2, detects the end of the tape in which there is no winding. ) reel B
At the same time, reel A and reel B are rotated with low torque.
This is done by rotating the magnetic tape 2 with a larger torque to unwind it, and detecting the reversal of the rotational direction of the reel B. Therefore, since the threader mechanism does not have any special play as in the past, loading and unloading of the magnetic tape 2 is possible.
The threader mechanism operates smoothly during unloading.

FIG. 3 shows an example of the direction detection circuit 4b.
) shows a circuit diagram, and (b) shows a timing chart of signals in each part of the circuit. The same figure (a
) is a register (REG) 31.
, 32, 33. 34, exclusive OR circuit (EOR) 35
．． 36.37, AND circuit (AND) 38, 39, JK
It consists of a flip-flop circuit (JK-FF) 40, the A-phase pulse output from the tacho generator 4a is input to REG31, and the B-phase pulse is input to REG31.
33. Then, the output (1) of REG31 is input to one input of EOR35 and REG32, and
Output (2) of G32 is input to one input of EOR36. Also, the output (3) of REG3 3 is EOR3
6 other human power and input to REG3 4, REG3
The output (4) of 4 is input to the other input of EOR35. And the output (5) of EOR35 is EOR37 and AN
It is input to one input of D3B, and the output of EOR36 (6
) is input to the other input of EOR37 and AND39. And the output (7) of EOR37 is AND38.39
and the output (8) of AND3B is JK-
To the J input of FF40, the output (9) of AND39 is JK-
Each is input to FF40's K human power. With this circuit, as shown in the same figure (b), the Q output of JK-FF40 (10, F 10) and page output (
11, BWD), different signals can be obtained depending on the rotation direction.

In the above embodiment, the output of the tachogenerator 4a is 5 per revolution.
00 pulse, the reversal of the rotation of reel B is instantaneously detected, and therefore the magnetic tape 2 on reel A is stopped with almost no reverse winding.

In this embodiment, the rotational direction detection means is configured by the tacho generator 4a and the direction detection circuit 4b based on its output, but the present invention is not limited to this, and can detect when the rotational direction of the reel B is reversed. It is fine as long as it is something.

[Effects of the Invention] As explained above, according to the tape end detection method of the present invention, in a magnetic tape device or the like equipped with a threader mechanism, there is no need to provide special play in the mechanism as in the past.
Therefore, the reliability of the magnetic tape device can be improved since unstable mechanical operation will not occur.

[Brief explanation of drawings]

Fig. 1 is a block diagram of main parts of a control system according to an embodiment of the present invention, Fig. 2 is a timing chart of the embodiment, Fig. 3 is an example of a direction detection circuit of the embodiment, and Fig. 4 is an explanation of the threader mechanism. It is a diagram. A, B... Reel, 1... Control circuit, 2.52... Magnetic tape, 3
a, 3b... Drive circuit, 4... Rotation direction detection means, 4a... Tacho generator, 4b... Direction detection circuit, 31-34... Register (REG), 35-37...
・Exclusive OR circuit (EOR), 38. 39...Logic product circuit (AND), 40...JK frimbufronbu times, W (JK-FF) 5l...cartridge, 53...threader arm, 54 .57...Threader position detection sensor, 55...
leader block. (a) Main part block diagram of a 14m system according to a major embodiment of the present invention. Timing chart for one example of Xj.

Claims (1)

[Claims] In a tape end detection method in a magnetic tape device, a rotation direction detection means (4) for detecting a rotation direction of the one reel (B) is provided, and the one reel (B) is set in a winding direction. and simultaneously rotate the other reel (A) to the one reel (B).
), and the one reel (
A tape end detection method in a magnetic tape device, characterized in that B) detects the point in time when the rotation reverses from the winding direction to the unwinding direction, and determines the point at which the rotation is reversed as the tape end.