JPH0233756A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To securely detect a tape pre-end and to reduce damage to a magnetic tape and a head by detecting the tape pre-end based on a ratio between both reels in rotative period at the time of a high speed tape travel. CONSTITUTION:When the subject device is set for the high speed tape travel, a drive circuit 6 is controlled by a tape speed control means 4 to perform a speed control for the high speed tape travel. Mean-while, period data of the reels R1 and R2 are measured by reel period measuring parts 21 and 22 to be inputted to a period ratio calculating means 11. A period ratio from the means 11 is compared with a reference period ratio set in a reference period ratio setting means 12 based on a bit of tape servo information from the means 4 by a comparison circuit 13. Then, when the period ratio between both reels reaches the reference period ratio, a bit of prescribed tape servo information is supplied to the means 4, where the reference period ratio for the high speed tape control is changed so as to control the tape speed to slow down. By this method, even when the travel is started up in the vicinity of the tape pre-end, the tape re-end can be securely be detected, thus reducing the damage to the tape and head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic recording and reproducing apparatus that detects a tape pre-end and controls the tape speed when a magnetic tape, which is an information recording medium, is run at high speed.

[Technical background of the invention and its problems]

The above-mentioned tape speed control performed by detecting the tape end is to reduce the tape speed in advance before winding of the magnetic tape is completed during high-speed tape running, and is performed, for example, in a digital audio tape recorder. .

FIG. 2 is a block diagram showing a tape speed control system of a digital audio tape recorder called R-DAT.

In the figure, reference numeral 11112 is a frequency generator that is mounted on a reel stand (not shown) and outputs pulse signals in response to the rotation of reels R1 and R2.

The reel period measuring section 21 + 22 is the frequency generator 11
Based on the pulse signal from 112, R1y R2
The rotation periods of both reels are added by an adder 3, and the period sum or square sum is inputted to the tape speed control means 4.

The tape speed control means 4 has a reference value (hereinafter referred to as a reference period sum) of a sum of periods or a sum of squares determined based on tape servo information from a microcomputer (not shown).
and the ambient or square sum manually input from the adder 3, and the comparison error is converted into a pulse width modulation signal (PWM
signal) and output to the output low-pass filter 5.

The low-pass filter 5 converts the PWM signal into a control voltage and outputs it to the drive circuit 6, and the drive circuit 6 drives the motor 7 according to the control voltage from the low-pass filter 5. Then, the motor 7 rotates the wheels R1+R2.

At this time, the rotational speed of the motor 7 is controlled by the control signal marked "-" so that the sum of the rotational periods of the reels R1 and R2 becomes the set reference periodic sum, and the running speed of the magnetic tape is kept approximately constant. High-speed tape running is performed under control such that

On the other hand, the changeover switch 8, through which the outputs from the reel cycle measuring sections 21 and 22 are input to contacts a and b, respectively, is switched according to the tape running direction by a microcomputer (not shown). When the magnetic tape runs in the forward direction (when the magnetic tape is wound on the reel R2), it is connected to the contact side and supplies the cycle data of the reel R2 to the comparator circuit 9, and when the magnetic tape runs in the reverse direction (when the reel When reeled on R2) is connected to the contact a side and the circumference 1sj of reel R1
The data is supplied to the comparison circuit 9.

The reference cycle setting means 10 also includes a tape speed control means 4.
Tape servo information is input from the tape servo information, and a reference cycle at the time of tape re-end is supplied to the comparator circuit 9 based on this tape servo information.

Then, the comparator circuit 9 compares the jJ ' updates the tape servo information that determines the tape speed at regular intervals, gradually reducing the running speed of the magnetic tape.

However, according to the conventional speed control as described above,
During stable high-speed tape running, the winding of the magnetic tape progresses and the rotation speed of the supply reel gradually increases, and when the rotation speed reaches a certain value (reference cycle), the tape ends. Because we are trying to judge,
When running from the tape bridle position, the reel cycle may not increase due to a delay in the rise and fall of the tape speed, and the tape bridle may not be detected.

As a result, the tape may reach the top or end of the tape at high speed, causing serious damage to the magnetic tape.
There were cases where the hend was damaged.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to reliably detect tape briend during high-speed tape running in a magnetic recording/reproducing apparatus, thereby reducing damage to the magnetic tape and head and increasing the tape speed.

[Summary of the invention]

The present invention detects tape briend based on the ratio of rotation periods of both reels during high-speed tape travel in a magnetic recording and reproducing device that controls tape speed during high-speed tape travel.
The tape speed was gradually reduced.

〔Example〕

FIG. 1 is a block diagram of an R-DAT according to an embodiment of the present invention, showing a speed control system for tape speed. In this figure, elements that are the same as those in FIG.

The period ratio calculation means 11 is a calculation means for calculating the ratio of the rotation periods of both reels RI + R2 input from the reel period measurement section 21. A reference period ratio is set based on the input tape servo information and is supplied to the comparison circuit 13. Note that this left half period ratio is set as the ratio of the rotation periods of both reels at the tape end position.

A comparison circuit 13 compares the reference period ratio with the period ratio calculation means 1.
1 to (Jt), and if the period ratio of both reels reaches the above reference period ratio, the tape servo information determined based on this reference period ratio is changed to the tape speed. It is supplied to the control means 4.

The tape speed control means 4 switches the reference period sum to be compared with the sum or square sum of the periods inputted from the adder 3 based on the tape servo information supplied from the comparison circuit 13, and uses the PWM signal outputted to the low-pass filter 5. Control tape speed to slow down.

Next, the overall operation will be explained.

When high-speed tape running is set by a microcomputer (not shown), the tape speed control means 4 outputs a PWM signal based on the sum or square sum of both reels R1 and R2 output from the adder 3 and the reference period sum. , a drive circuit 6 is controlled via a low-pass filter 5 to control the speed of high-speed tape running.

During this period, the period data of both reels Rl + R2 measured by the reel period measuring section 21 + 22 is sent to the period ratio calculation means 1.
Entered into 1, Zhou! The period ratio is calculated by the ili ratio calculation means 11 and inputted to the comparison circuit 13. and tape 4) from tape speed control means 4).

- The reference voltage 1υj ratio set based on the
(The signal is supplied from the cycle ratio setting means 12 to the comparison circuit 13, which compares the reference piece ill ratio with the cycle ratio of both reels.

Then, when the period ratio of both reels reaches the reference circle jlJl ratio, tape servo information determined based on this reference voltage 1tll ratio is supplied to the tape speed control means 4, and the tape speed control means 4 controls the high speed tape. The tape speed is controlled to be slow by switching the reference cycle sum during running.

By the way, the ratio of the rotation periods of both reels when the tape is running is
If the tape winding amount is the same, it will be constant regardless of the tape running speed, so even if the tape starts running near the tape bridle position, the tape bridle will be detected regardless of the tape speed at the start. can do.

In addition, if the tape length of the cassette half used is different,
Although it is necessary to change the setting value of the reference period ratio at the tape end position, multiple reference period ratios and tape servo information corresponding to different tape lengths can be stored in advance, and the tape length of the cassette half to be used can be changed. It may be selected as appropriate depending on the situation.

In the above embodiment, the PWM signal from the tape speed control means 14 that controls the tape speed is converted into a control voltage by the low-pass filter 6 to drive and control the motor.
Output the corrected reference period sum as a predetermined reference voltage,
The control voltage may be generated by comparing the voltage obtained by F-V converting the period sum data supplied to the tape speed control means 14 with the reference voltage.

〔Effect of the invention〕

As explained above, according to the present invention, in a magnetic recording/reproducing device such as R-DAT, tape pre-end is detected based on the ratio of rotation periods of both reels during high-speed tape running, and the tape speed is gradually reduced. Therefore, it is possible to reliably detect the tepbrient during high-speed tape running.

This makes it possible to reduce damage to the tape and head and to increase the tape speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a portion related to speed control in an R-DAT according to an embodiment of the present invention, and FIG. 2 is a block diagram of a portion related to speed control in a conventional R-DAT. II, 12... Frequency generator, 21.22...
- Reel cycle measuring section, 3... Adder, 4... Tape speed setting means, 5... Low pass filter, 6... Drive circuit, 7... Motor, 11... Period ratio calculation means ,
12 reference period ratio setting means, 13...comparison circuit.

Claims (1)

[Scope of Claims] A magnetic recording and reproducing device having a tape speed control means for controlling the tape speed by detecting a tape pre-end before the end of winding during high-speed tape running, the device comprising: reel period measuring means for measuring the rotation period of the reels; period ratio calculation means for calculating the rotation period ratio of both reels;
A high-speed tape, comprising a reference period ratio setting means for setting a reference period ratio based on the tape speed data of the tape speed control means, and a comparison circuit for comparing the period ratios of the period ratio calculation means and the reference period ratio setting means. A magnetic recording/reproducing device characterized in that a tape pre-end is detected based on the comparison output of the comparison circuit during running.