JPS6052489B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus that runs and drives tapes having different reel sizes, such as an open-reel tape recorder.

For example, in reel-to-reel tape recorders, the reel on which the magnetic tape is wound has various sizes, such as 3 inches, 5 inches, 7 inches, 10 inches, and 14 inches, and each has a large difference in moment of inertia. Abnormal tension occurs at the start of running, and each reel has different running start-up characteristics during fast forwarding and rewinding, resulting in adverse effects such as difficulty in cueing. The present invention eliminates the above-mentioned conventional drawbacks and changes the upper limit of the rotational torque of the motor that rotates the supply and take-up reels in accordance with the size of the reel to be driven. The object of the present invention is to provide a magnetic recording/reproducing device which has optimum characteristics and allows easy cueing operations without damaging the tape.

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a reel-to-reel type tape recorder 1 to which an embodiment of the present invention is applied, and includes a tape drive section 2 and an amplifier section 3. As shown in FIG.

A mode changeover switch, a level adjustment knob 5, a level meter 6, and the like are arranged on the front panel of the amplifier section 3.
The tape drive section 2 includes a head section 7 in which recording and reproducing magnetic heads, capstans, etc. are arranged at predetermined positions, a pinch roller 8, a tension roller 9, and supply and take-up reel drive shafts 10s and 10. placed at each location. Reel 11 for reel drive shaft 10s/10
The reels 11s and 11 are attached to the reel hubs 12s and 12 and the reel flange 13.
s.13 and reel hub 12s.12
A magnetic tape 14 is wound around the . Here, each reel drive shaft 1s.10 is rotationally driven by an independent motor. In such an open-reel type tape recorder 1, there are generally various sizes of the reel 11 that can be used, such as 3, 5, 7, 10, and 14 inches.

The total amount of the magnetic tape 14 wound (for example, the total area of the part where the magnetic tape 14 is wound in a plane perpendicular to the reel axis) differs depending on the reel size. By finding the total amount,
You can determine the reel size. In this example,
As the total amount of tape, the sum S of the areas Ss-St of the magnetic tapes 14 wound around the reel hubs 12s and 12t of the respective reels 11s and 11t is used.

That is, as shown in FIG.
The winding radius of the magnetic tape 14 wound at t is R,,rtl
When the radius of the reel hubs 12s and 12t is Rh, the area S takes a constant value depending on the reel size. Here, for convenience of calculation, ,,. Let's find each area Ss'', SV, S'' like a breather,
For each reel size, the tape area S'' as the total amount of tape is determined in advance.

This is the winding radius of raw tape (unused tape), which is Rl4 for 14 inches and Rl for 10 inches.
When the radius of the reel hub is 14 inches, Rhl4, 10 inches, RhlO, etc., the tape area S'' for each reel size is as follows.

In addition, regarding the above area Ss″・St″, each reel 1
Total from tape winding radius R5, rt of 1s/11t! These radii Rs, r, are calculated for each reel 11s and 11
Depending on the rotational speed Ns,n of t and the running speed of the magnetic tape 14, the following equation is obtained.

Therefore, by detecting these rotational speeds Ns, n, and traveling speed V by some means, the above-mentioned area Ss
", SVl and these +μs" can be calculated. FIG. 2 is a block diagram schematically showing a specific example of a circuit used in such an embodiment.

The reel drive shaft 10s of the supply reel 11s is a motor 20s.
As a result, the reel drive shafts 10t of the take-up reel 11t are rotated independently by the motors 20t. Each reel drive shaft 10s, 10t is provided with a rotation detector 21s, 21t that detects the respective rotation and outputs a pulse. Pulses from the rotation detectors 21s and 21t are sent to the calculation circuit 26 as rotation speed signals via force counters 22s and 22t, respectively. Here, the rotation number signal is a signal indicating the number of rotations of the reel per unit time, and this can be done, for example, by gate-controlling the counters 22s and 22t with a pulse signal at a unit time interval from the input terminal G. The number of input rotation detection pulses may be counted and output. Next, the running speed of the magnetic tape 14 may be detected in conjunction with a tape speed changeover switch, but in this embodiment, the rotation of the roller 23 that guides the tape running is detected by the rotation detector 24. A calculation circuit 26 calculates a tape running speed signal via a counter 25.
I am sending it to This tape running speed can be obtained by multiplying the outer circumferential length of the roller 23 by the number of revolutions. here roller 2
3 can use a tension roller 9, a pinch roller 8, a capstan or other guide rollers, but in the case of the pinch roller 8 or capstan, they separate from the magnetic tape 14 during fast forwarding and rewinding modes. Tape running speed cannot be detected. Next, calculation circuit 2
6, the signals of the supply and take-up reel rotational speeds Ns, n, obtained from the counters 22s and 22t, and the counter 2
Based on the tape running speed signal obtained from step 5, perform step 4 above.
, 5 are used to determine the tape winding radii Rs and rt of each reel, and then the area S'' is determined from the above-mentioned equation 3'' and sent to the comparator 31.

By the way, by substituting the 4 (goods) formula into the 3'' formula, the following is obtained. FIG. 2 shows an example of the internal configuration of the calculation circuit 26 in accordance with the calculation procedure of the 6 formula.

That is, the number of revolutions Ns from the counters 22s and 22t,
For the signal n, a circuit section 27 takes the reciprocal of the square value.
s.27t to the adder 28, and this adder 28
The output from the multiplier 30 is sent to the multiplier 30. Further, the signal of the tape running speed v from the counter 25 is sent to a multiplier 30 via a circuit section 29 that takes the square of the signal. The multiplier 30 is a constant of 6 formulas! Each of the above circuit sections 28 and 2
9 and sends a signal of the area S'' to the comparator 31.Next, the memory circuit 32 stores the tape area for each reel size of 14 inches, 10 inches, etc. Values such as S''14, S''10, . . . are stored in advance, and signals indicating these values are sent to the comparator 31.

In the comparator 31, the tape area S from this storage circuit 32
``14, S'' 10, . . . and the tape area S'' from the calculation circuit 26 are compared to determine the reel size. .

In addition, for example, each tape area S″14, S″10,
. . . etc., the error ranges of the upper and lower predetermined widths are set so that they do not overlap with each other, and the detected tape area S'' is determined according to which reel size tape area falls within the above error range. , the reel size may be determined.This comparator 31 has output terminals Xl4, XlO, . Signals are output only from the terminals.

These output terminals Xl4, XlO, . . . are control input terminals Yl4 of the torque limiters 33s and 33t, respectively.
, YlO, . . . Next, the torque limiters 33s and 33t control the upper limit values of the rotational torques of the motors 20s and 20t for driving the supply and take-up reels to optimal values, respectively, according to the determined reel size.

The outputs from these torque limiters 33s and 33t are sent to the motor 2 via motor drive circuits 34s and 34t, respectively.
It is sent to 0s/20t. These torque limiters 33s and 33t can be used in various configurations, but
As a specific example, the configuration shown in FIG. 3 will be explained.
The torque limiter 33 shown in FIG. 3 has a current feedback type circuit configuration. First, at least as many resistors Ra, Rb, Rc, etc. as the number of types of reel sizes are connected in series to the motor 20, and each connection part of these resistors is connected to the switching terminals Za, Zb, Zc, etc. of the switching switch 35. ... are connected to each other. This changeover switch 35 is switched by a reel size discrimination signal supplied to the control input terminal Y, and has two diodes 36 and 37 connected in parallel in opposite directions, and these diodes 36 and 37.
It is connected to the negative side input terminal of a motor drive circuit 34 using a differential amplifier via a resistor 38 connected in parallel with . A negative input terminal of this motor drive circuit 34 is connected to an input terminal 39 via a resistor, and a positive input terminal is grounded. An output terminal of this motor drive circuit 34 is connected to the motor 20. To briefly explain the operation of the torque limiter 33 shown in FIG.
5 is switched according to the determined reel size as described above. For example, when the selector switch 35 is switched to terminal h, the voltage Va at terminal h is caused by the current 19 flowing through the motor 20. .

This voltage a is the voltage at which the diodes 36 and 37 conduct.
In this case, the gain of the current feedback loop becomes 0, so that no more current flows through the motor 20, and this current of 1M
A torque greater than the torque determined by , will not be generated. Similarly, the changeover switch 35 changes according to the reel size determination signal supplied to the control input terminal Y.
The upper limit value of the current h flowing through the motor 20 changes, and the upper limit value of the torque also changes accordingly. 1. Therefore, the motor 20 is controlled to provide the optimum torque upper limit value according to the reel size.

In this case, the optimal upper limit of torque for each reel size should be determined by taking into account the quality of the magnetic tape used and the frictional force of the tape running system, and ensuring that the tension is sufficient to avoid damaging the tape when running the tape, and that the reel It goes without saying that the value should be set to such a value that abnormal tension does not occur at the start of the rotation operation, or the start-up characteristic is too steep, making it difficult to perform read and review operations. As is clear from the above explanation, the reel sizes of the supply and take-up reels 11s and 11t attached to the open-reel type tape recorder 1 etc. are determined by the rotational speed of each reel 11s and 11t and the magnetic tape 1.
4, the calculation circuit 26 calculates the total tape amount, for example, the total tape area S'', and stores this and the storage circuit 32.
The comparator 31 compares the total amount of tape corresponding to each reel size stored in , for example, the total tape area S''14, S''10, . . . , to automatically discriminate.

Next, depending on the determined reel size, the torque limiter 33s*33t is set to the reel drive motor 20s*33t.
The 20t torque limit has been adjusted to the optimum value. Therefore, when there are various reel sizes used and the moment of inertia of each reel is different, as in the reel-to-reel tape recorder 1, automatic control is performed so that the upper limit of the rotational torque is optimal for each reel size. Therefore, when the tape is running, the
The exposure characteristics and the rise characteristics at the start of reel rotation are stabilized within a certain range, and the tape position can be easily detected during print and review operations without damaging the tape.

Furthermore, since the above control is performed completely automatically, manual operations can be performed with the same amount of effort as in the past.

[Brief explanation of drawings]

The drawings all show one embodiment of the present invention, and FIG. 1 is a front view of a reel-to-reel tape recorder 1 to which the embodiment is applied, and FIG. 2 is a block diagram showing the schematic configuration of the embodiment. FIG. 3 is a circuit diagram showing a specific example of the configuration of the torque limiter 33 shown in FIG. 2. 1...Reel-to-reel tape recorder, 11
s...supply reel, 11t...take-up reel, 14...magnetic tape, 20s/20t...
...Motor, 21s, 21t, 24... Rotation detector, 26... Calculation circuit, 31...
Comparator, 32... Memory circuit, 33...
Torque limiter.

Claims (1)

[Claims] 1. A rotation detector that detects the rotation of the supply reel and the take-up reel, a speed detector that detects the tape running speed, and a tape wound on the supply reel and take-up reel based on the detection signals from these detectors. A calculation circuit that calculates the total amount of tape, a storage circuit that stores the total amount of tape for each reel size in advance, and a determination that determines the reel size by comparing the total amount of tape from the calculation circuit with the total amount of tape in the storage circuit. 1. A magnetic recording and reproducing apparatus comprising: a means for reeling the reel; and a torque limiter for limiting the torque of the reel motors of the supply reel and take-up reel according to the determined reel size.