JPS645389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape device used, for example, as an image file device of an image information storage and retrieval device.

In recent years, various image information storage and retrieval devices have been developed that file (store) a large amount of image information such as documents generated in an image file device, search it as needed, and output it as a record (or display output). has been made into Generally, microfilm devices and the like are often used as image file devices in such image information storage and retrieval devices, but recently magnetic tape devices have been considered as an alternative to these devices.

This magnetic tape device runs an endless magnetic tape having a large number of recording tracks along the running direction, and moves a magnetic head in a direction perpendicular to the running direction of the running magnetic tape to record arbitrary recording tracks. By selecting a recording track, a video signal obtained by optically reading and scanning image information is recorded on the selected recording track via a magnetic head, or the recorded content is selectively reproduced. It is.

However, image information storage and retrieval devices are generally required to quickly and accurately file (storage) and retrieve image information in view of their intended use. Therefore, in a magnetic tape device used as an image file device in such an image information storage and retrieval device, information signals must be recorded or reproduced quickly and accurately on the magnetic tape. To this end, it is necessary for the magnetic head to quickly and accurately access a large number of recording tracks set on the magnetic tape.

Recently, in order to achieve this purpose, at least one of each recording track approximately in the center with respect to the tape width is designated as an index recording track, and image information recorded on other recording tracks is stored on this index recording track. A device has been proposed in which index information serving as a search code is recorded, and a magnetic head is positioned on this index recording track during standby when the recording track is not accessed.

However, with this method, the magnetic head is fixed to the index recording track during standby periods other than when the recording track is being accessed, resulting in the following problem. That is,
FIG. 1 shows experimental results of changes in amplitude of a reproduced signal and reproduction error rate over time when information recorded on a magnetic tape is reproduced. In this figure, curve _A1 shows the reproduced signal amplitude over time when the magnetic head is positioned on a fixed recording track, and curve _A2 shows the error rate at that time. Further, a curve _B1 shows the reproduced signal amplitude with respect to a change over time when information on another recording track on which the magnetic head is not located is reproduced, and a curve _B2 shows the error rate at that time. As is clear from this figure, the reproduction information from the recording track where the magnetic head is fixed is significantly degraded compared to other recording tracks. One of the reasons for this influence is thought to be that the reproduction signal amplitude of the recording track on which the magnetic head is located deteriorates due to changes in the air gap that occurs between the magnetic head and the magnetic tape. Note that the tracks that are affected in this way are not only the index recording track, but also other recording tracks adjacent to the index recording track because the tape contact portion of the magnetic head is generally larger than the width of one track. .

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a single or multiple non-recording tracks in which no information is recorded, and to use this during standby when no recording track is selected. By positioning the magnetic head on a non-recording track, the magnetic head can quickly and accurately access each recording track on the magnetic tape without affecting the various information on the recording track on which information is recorded. The object of the present invention is to provide a magnetic tape device that makes it possible to perform the following functions.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 schematically shows a cassette tape and its feeding mechanism used in a magnetic tape device according to the present invention.A fixed reel 2 that does not rotate is provided in a case 1. Width is 1/2 inch (approximately 12.7m/m) and length is approximately 36m
A magnetic tape 3 is wound endlessly. When the cassette tape configured as described above is loaded, the tape wound around the innermost circumference of the magnetic tape 3 wound around the reel 2 is loaded onto the reel 2.
The magnetic tape 3 is pulled out through a window 2a provided in the magnetic tape 3, is fed at a high speed of about 5 m/sec by a capstan 4 and a pinch roller 5, and then rewound to the outermost portion of the magnetic tape 3. Therefore, the magnetic tape 3 rotates once in approximately 7.2 seconds. The magnetic tape 3 includes, for example, a third
parallel to its running direction a, as shown in the figure.
200 recording tracks (track width approximately 40 μm, inter-track pitch approximately 52 μm) 6 are set.
If the recording tracks 6 are sequentially numbered "0, 1, 2, ... 198, 199" from the bottom, then, for example, the track number 2 located approximately in the center is
The book (track numbers ``99, 100''; track number ``99'' is a spare track) has an index recording track 6 ₁ for recording an index code representing the content of image information and an address for recording the information signal. The almost adjacent track (track number "98") is a non-recording track 6 that does not record any information.
_2. The remaining 197 tracks (track numbers 0-97, 101-
199'') is the information recording track 6 for recording information signals.
It has become ₃ . The position of the non-recording track ₆₂ is preferably near the index recording track ₆₁ so that the magnetic head can access each recording track on the magnetic tape 3 quickly and accurately. However, since the tape contact portion of the magnetic head is generally larger than the width of one track, it is ideal to position it on a track slightly distant from the index recording track ₆₁ . To record or reproduce information signals on the magnetic tape 3, a magnetic head 7 provided near the capstan 4 is moved back and forth in micron units in a direction b perpendicular to the running direction a by an access mechanism to be described later. This is done by selecting an arbitrary recording track 6. Note that the magnetic head 7 is actually a two-gap head that also has an erasing function.

FIG. 4 schematically shows an access mechanism for the magnetic head 7, which is constructed as follows, for example.
That is, by rotationally driving the pulse motor 8 with a drive pulse, the motor gear 9 is rotated by a constant angle, and the head screw 11 connected to the gear 10 is rotated via the screw gear 10 that meshes with the gear 9. As a result, the head holder 12, which is screwed onto the screw 11 and to which the magnetic head 7 is fixed, is moved upward or downward (in the direction of arrow b) one track at a time. In addition, the motor gear 9 and the screw gear 10
For example, microswitches 13 and 14 are provided in the vicinity of each of them. One of the micro-switches 13 is for detecting the rotational phase of the pulse motor 8 (that is, the minute position of the magnetic head 7). This is turned on each time the detector is turned on, and this will be referred to as the first detector hereinafter. The other micro switch 14 is
This is to roughly detect that the magnetic head 7 is located at the lowest end (lowest stage) track (track number "0") of the recording track 6 on the magnetic tape 3, and this will be referred to as the second detection. It is called a vessel. These first and second detectors 13 and 14
The magnetic head 7 is configured to be positioned (relatively oriented) to the lowest track (track number "0") when the detection operations are performed at the same time. Note that when three drive pulses are input to the pulse motor 8, the magnetic head 7 moves by one track, and the pulse motor 8
is designed to rotate once when six drive pulses are input.

FIG. 5 shows a head control circuit for controlling the movement of the magnetic head 7, and is constructed as follows, for example. That is, 16 is a reset circuit which outputs a reset signal when the magnetic tape device is powered on. Reference numeral 17 denotes an AND circuit which calculates the AND of the respective output signals of the first and second detectors 13 and 14. 18
is a main control unit such as a CPU, which is cleared (initialized) by the output of the reset circuit 16 and is supplied with the output of the AND circuit 17. 19 is FF
In the circuit, the output of the reset circuit 16 is used to reset the output, and the output of the AND circuit 17 is used to set the output. 20
is a storage means, such as a track register, for storing position information indicating the current position of the magnetic head 7, which is cleared by the output of the reset circuit 16, and counts up or down according to the output of the comparison circuit 23, which will be described later. Reference numeral 21 denotes a constant register in which, for example, a track code of track number "98" (binary code of numerical value "98") is stored, and is controlled by the main control section 18. 22 is an address register which stores the contents of the constant register 21 or the main control unit 1.
The designated track code (binary code of the designated track number) from 8 is stored. 23 is a comparison circuit that compares the contents of the track register 20 and the contents of the address register 22 in terms of magnitude and coincidence, and outputs the comparison results to the track register 20 and the main control section 18. 24 is a pulse motor drive circuit which drives the pulse motor 8 according to drive pulses supplied from the main control section 18 and outputs a count pulse every time the pulse motor 8 is driven by one track (three steps). .
25 is an AND circuit whose gate is opened by the set output of the FF circuit 19, and inputs the count pulse output from the pulse motor drive circuit 24 to the track register 20.

Next, the operation in the above configuration will be explained. Now, when the cassette tape shown in FIG. 2 is loaded and the power switch (not shown) is turned on, the reset circuit 16 outputs a reset signal, which causes the main control section 18, FF circuit 19, and track register 20 to operate. Each will be cleared. As a result, the main control section 18 sequentially supplies drive pulses to the pulse motor drive circuit 24 along with a command signal for moving the magnetic head 7 downward (in the direction of track number "0"). Therefore, the pulse motor drive circuit 24 rotationally drives the pulse motor 8 in a direction to move the magnetic head 7 downward.
At this time, a count pulse is output from the pulse motor drive circuit 24, but since the FF circuit 19 is reset and the gate of the AND circuit 25 is closed, the count pulse is not input to the track register 20. In this way, the magnetic head 7 moves downward, and then, when both the first and second detectors 13 and 14 operate to detect, the AND circuit 1
7 is established, and its output signal is supplied to the main control section 18 and also to the FF circuit 19. Then, the FF circuit 19 is set, and the main control section 18 stops supplying drive pulses to the pulse motor drive circuit 24. As a result, the magnetic head 7
is located on the recording track with track number "0", that is, the lowest information recording track ₆₃ , which matches the contents of the track register 20 (which has been cleared to "0"). in this way,
When the power is turned on, the track register 20 is cleared and the magnetic head 7 is automatically moved until both the first and second detectors 13 and 14 output detection signals.

In this way, when the magnetic head 7 is located at the lowest recording track, the main control section 18 next moves the magnetic head 7 to the non-recording track 6 ₂ with track number "98".
, the contents of the constant register 21 (binary code of numeric value "98") are read out and stored in the address register 22. Then, the comparison circuit 23
compares the contents of the track register 20 with the contents of the address register 22, and supplies the comparison result to the main control section 18 and the track register 20. That is, in this case, the contents of the track register 20 (track code indicating the position of the magnetic head 7) are "0" and the contents of the address register 22 (designated track code) are "98", so the address register 22 is larger. Outputs a signal indicating this. As a result, the track register 20 is set to up-count mode, and the main controller 18 determines that the moving direction of the magnetic head 7 is upward (in the direction of track number "199") based on the above comparison result, and Drive pulses are sequentially supplied to the pulse motor drive circuit 24 along with a command signal for moving the head 7 upward. Therefore, the pulse motor drive circuit 24 rotates the pulse motor 8 in a direction to move the magnetic head 7 upward, and outputs a count pulse every time the pulse motor 8 is driven by one track. This output count pulse passes through the AND circuit 25 whose gate is open at this time, and then passes through the track register 2.
0, which causes the track register 20
performs an up-count operation, and its contents are a track code (binary code of the track number) indicating the current position of the magnetic head 7. In this way, the contents of the track register 20 sequentially change (count up) as the magnetic head 7 moves, and store the position information of the magnetic head 7. The contents of address register 20 are constantly compared to see if they match the contents of address register 22, and the comparison result is supplied to main control section 18. As a result, the main control unit 18 controls the comparator circuit 2
The next drive pulse is output to the pulse motor drive circuit 24 while confirming that the mismatch signal is output from the pulse motor drive circuit 24.

Then, when the magnetic head 7 moves upward and the content of the track register 20 becomes "98", it matches the content of the address register 22, "98", so the comparison circuit 23 outputs a match signal.
Then, the main control section 18 controls the pulse motor drive circuit 2.
The supply of drive pulses to magnetic head 7 is stopped, and
stop moving. As a result, the magnetic head 7
is located on the unrecorded track ₆₂ with track number "98". In this way, when the power is turned on, the magnetic head 7 is positioned on the information recording track ₆₃ with track number "0" and then automatically moved to the non-recording track ₆₂ . Therefore, the magnetic head 7 stands by in this state for head access for reproducing or recording information signals.

Next, when accessing any track of the information recording track ₆₃ , the command is given to the main control section 18, and the main control section 18 stores the designated track code in the address register 22. Then, the comparison circuit 23 compares the contents of the registers 20 and 22 in the same manner as described above, and outputs the result. For example, if the specified track code stored in the address register 22 is "50", then the content of the track register 20 is "98", so a signal indicating that the track register 20 is larger is output. As a result, the track register 20 is set to the down count mode, and the main controller 18 determines that the moving direction of the magnetic head 7 is downward based on the above comparison result, and pulses the command signal and drive pulse for this purpose. Supplied to the motor drive circuit 24. Therefore, the pulse motor drive circuit 24 rotates the pulse motor 8 in a direction to move the magnetic head 7 downward, outputs a count pulse, and supplies the count pulse to the track register 20.
As a result, the track register 20 performs a down-count operation, and thereafter, as described above, the contents sequentially change (down-count) as the magnetic head 7 moves. Thereafter, when the content of the track register 20 becomes "50", it matches the content of the address register 22, "50", so the movement of the magnetic head 7 is stopped here in the same way as described above. As a result, the magnetic head 7 is located at the information recording track ₆₃ with track number "50", and the information signal is then reproduced or recorded on the recording track ₆₃ . When the reproduction or recording of the information signal is completed, the main control unit 18
stores the contents of the constant register 21 in the address register 22 in order to position the magnetic head 7 again on the non-recording track ₆₂ . As a result, the magnetic head 7 undergoes the same operation as described above, and the non-recording track 6 is removed.
₂ and waits for head access for reproduction or recording of the next information signal. In this way, when the recording track 6 is on standby except when access is being made, the magnetic head 7 is automatically returned to the non-recording track ₆₂ approximately in the center where no information is recorded.

With the above configuration, the non-recording track ₆₂ is provided approximately at the center of the magnetic tape 3 with respect to the tape width, and the magnetic head 7 is positioned on this non-recording track ₆₂ during standby when no recording track 6 is selected. By doing so, there is no influence at all during reproduction unlike in the conventional case where the magnetic head is located on a recording track on which information is recorded. Furthermore, since the magnetic head 7 is automatically positioned on the non-recording track ₆₂ in the approximate center at all times except when the head is accessed, the magnetic head 7 can be quickly and accurately positioned on the recording track 6 in either the up or down direction. can be accessed. Furthermore, by providing the index recording track ₆₁ approximately at the center of the tape width of the magnetic tape 3, for example, when searching for information, the index recording track ₆₁ is first reproduced;
Next, the information recording track ₆₃ is reproduced based on the reproduced content, and since the non-recording track ₆₂ during standby is located near the index recording track ₆₁ , reproduction can be performed quickly.

In the above embodiment, the magnetic head 7 is positioned at the lowest track of the recording tracks 6 when the power is turned on, but it may be positioned at the uppermost track. Also, unrecorded track 6 ₂
Although the case where the magnetic tape 3 is provided near the index recording track ₆₁ at approximately the center of the tape width of the magnetic tape 3 has been described, if the main purpose is to eliminate the above-mentioned influence during reproduction, the It is not necessary to provide it approximately at the center of the tape 3.
In this case, the access speed is lower than when the magnetic tape 3 is provided approximately in the center. Furthermore, although the case has been described in which the present invention is implemented in a magnetic tape device used as an image file device of an image information storage and retrieval device, it can be similarly implemented in a magnetic tape device that records or reproduces other information signals.

As described in detail above, according to the present invention, a single or multiple non-recording tracks are provided in which no information is recorded, and the magnetic head is positioned on the non-recording tracks during standby when no recording track is selected. This allows the magnetic head to quickly and accurately access each recording track on the magnetic tape without affecting the various information on the recording tracks on which information is recorded. It is possible to provide a magnetic tape device that provides the following effects.

[Brief explanation of drawings]

FIG. 1 is a diagram showing experimental results of changes in the amplitude of the reproduced signal and the reproduction error rate over time when information recorded on a magnetic tape is reproduced, and FIGS. 2 to 5 are examples of an embodiment of the present invention. Fig. 2 is a block diagram schematically showing the cassette tape and its feeding mechanism, Fig. 3 is a detailed diagram showing the track structure of the magnetic tape, and Fig. 4 is a schematic diagram of the access mechanism of the magnetic head. FIG. 5 is a block diagram showing the structure of the head control circuit. 3...Magnetic tape, 6...Recording track, ₆₁ ...Index recording track, ₆₂ ...No recording track,
6 ₃ ...information recording track, 7...magnetic head, 18
...Main control unit, 20...Track register, 21...Constant register, 22...Address register, 23...Comparison circuit.

Claims (1)

[Claims] 1 A magnetic tape having a plurality of recording tracks is run along the running direction, and a magnetic head is moved in a direction perpendicular to the running direction of the running magnetic tape to select an arbitrary recording track, thereby recording information. In a magnetic tape device for recording or reproducing images, the recording tracks are divided into information recording tracks for recording image information, index recording tracks for recording unique index information indicating the content of the image information, and simple recording tracks for recording no information at all. Consisting of one or more unrecorded tracks,
1. A magnetic tape device comprising control means for positioning the magnetic head on the non-recording track during standby when no recording track is selected.