JPH04307449A - magnetic tape running device - Google Patents

Abstract

PURPOSE:To surely detect a position of a magnetic tape running whatever speed in traveling the magnetic tape by reading a target value detecting signal to be outputted from a target value detecting means. CONSTITUTION:In the subject magnetic tape transport device, first of all, the magnetic tape 1 is transported at a fixed apeed for a given period of time, and meanwhile, a total area of the magnetic tape wound around a supply reel 2 and a take-up reel is calculated inside the device, and is stored in a memory 9. Then, under the holding state of this stored value, rotating periods of the supply reel and the take-up reel are measured, and the measured rotating periods of both reels are stored in the memory, and from the total area value of the magnetic tape held in the memory, winding diameters of the magnetic tape wound around both reel parts are calculated to be compared with target winding diameter values. By repeating such operations in a fixed period, the magnetic tape position can surely be detected at whatever speed is required for transporting the magnetic tape.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to video tape recorders (VTR) and digital audio tape recorders (DA).
This invention relates to a magnetic tape running device that can be used for applications such as T).

0002

2. Description of the Related Art In recent years, magnetic tape running devices for running magnetic tapes such as VTRs and DATs at variable speeds have been put into practical use.

An example of the above-mentioned conventional magnetic tape running device will be described below with reference to the drawings.

FIG. 5 shows a block diagram of a conventional magnetic tape running device. In FIG. 5, 1 is a magnetic tape, 2 is a supply reel, 3 is a take-up reel, 4 is a magnetic tape drive circuit that stably drives the magnetic tape 1 at a variable speed;
5 detects whether or not the running speed of the magnetic tape 1 from the magnetic tape drive circuit 4 is within the running speed range of the magnetic tape that is set when changing the running speed, and the point in time when the running speed of the magnetic tape 1 falls within the running speed range. By counting the period of the running speed signal of the magnetic tape 1 using the internal clock,
A magnetic tape running speed detection circuit outputs the running speed of the supply reel 2 as a digital value, and 6 is a reel cycle measuring circuit that measures the period of a frequency signal proportional to the rotational speed of the supply reel 2 and outputs a digital value corresponding to the rotational speed. , 7 is a reel period measuring circuit that measures the period of a frequency signal proportional to the rotational speed of the take-up reel 3 and outputs a digital value corresponding to the rotational speed; 10 is an output value of the magnetic tape running speed detection circuit 5; The winding diameter R1 of the magnetic tape 1 wound around the supply reel 2 side and the magnetic tape 1 wound around the take-up reel 3 side are determined from the output values of the reel period measuring circuits 6 and 7.
Calculate the winding diameter R2, and calculate the winding diameter R1, R
11 is a magnetic tape winding diameter target value output circuit that outputs an arbitrarily settable target value of the winding diameter of magnetic tape 1 as a digital value; 12 is a magnetic tape winding diameter target value output circuit that outputs a digital value corresponding to the value of 2; A magnetic tape winding diameter difference detection circuit that calculates the difference between the output value of the magnetic tape winding diameter calculation circuit 10 and the output value of the magnetic tape winding diameter target value output circuit 11 and outputs it as a digital value; 13 is a magnetic tape 1 that can be set arbitrarily; A winding diameter difference tolerance output circuit 14 outputs the tolerance of the winding diameter difference in a digital value; Reference numeral 15 designates a target value detection signal output from the target value detection circuit 14, which outputs a signal to the outside only occasionally.

FIG. 6 is a diagram for specifically explaining a method of calculating the winding diameters R1 and R2 of the magnetic tape 1 of a conventional magnetic tape running device. In Figure 6,
21 is a hub of the cassette tape attached to the supply reel 2 side, and 22 is a hub of the cassette tape attached to the take-up reel 3 side.

The operation of the magnetic tape running device constructed as described above will be explained below with reference to FIGS. 5 and 6.

First, the magnetic tape 1 is connected to a magnetic tape drive circuit 4.
When the magnetic tape starts running at a certain speed Vt in the direction of arrow a or b, the magnetic tape running speed detection circuit 5 arbitrarily sets an upper limit value and a lower limit value as a permissible range around the speed Vt. It is detected whether the traveling speed is within the permissible range of the speed Vt. When the running speed of the magnetic tape 1 falls within the permissible range of Vt, the running speed Vt of the magnetic tape 1 is calculated as a digital value by counting the period of the running speed signal of the magnetic tape 1 using an internal clock. It is output to the tape winding diameter calculation circuit 10.

Further, as the magnetic tape 1 runs, the supply reel 2 and the take-up reel 3 rotate at a certain speed, and the reel period measuring circuits 6 and 7 detect the supply reel 2 and the take-up reel 3.
and the period of the frequency signal proportional to the rotational speed of the take-up reel 3, and outputs a digital value corresponding to the period to the magnetic tape winding diameter calculation circuit 10. The magnetic tape winding diameter calculation circuit 10 calculates the winding diameter of the magnetic tape 1 wound on the supply reel 2 side based on the running speed of the magnetic tape 1 from the magnetic tape running speed detection circuit 5 and the reel period from the reel period measuring circuits 6 and 7. R1 and the winding diameter R2 of the magnetic tape 1 wound on the take-up reel side are calculated, and the calculated R1 and R2 are each output as digital values to the magnetic tape winding diameter difference detection circuit 12.

Next, the magnetic tape winding diameter difference detection circuit 12 calculates R1,
Calculate the difference between R2 and the target value of the winding diameter of the magnetic tape 1, which can be set arbitrarily and which is output as a digital value from the magnetic tape winding diameter target value output circuit 11, and output the difference as a digital value to the target value detection circuit 14. do. At this time, the winding diameter difference tolerance output circuit 13 outputs, as a digital value, an arbitrarily settable tolerance within which the difference between the winding diameter values R1 and R2 of the magnetic tape 1 and the target value should be within. It is output to the target value detection circuit 14.

The target value detection circuit 14 detects the difference between R1 and R2 from the magnetic tape winding diameter difference detection circuit 12 and the winding diameter target value, and the tolerance of the winding diameter difference from the winding diameter difference tolerance output circuit 13. The winding diameters R1 and R2 of the magnetic tape 1 reach the target winding diameter value only when the difference between the R1 and R2 and the target winding diameter value falls within the permissible value of the winding diameter difference. Therefore, the target value detection signal 15 is outputted to the outside.

By performing the above-described series of operations at predetermined regular intervals, the winding diameter R1 of the magnetic tape 1 wound around the supply reel 2 side and the take-up reel 3 can be adjusted.
The winding diameter R2 of the magnetic tape 1 wound around the side can be calculated in real time. In addition, the magnetic tape winding diameter target value output circuit 11 sets the target winding diameter value of the magnetic tape 1 to the hub diameters r1 and r2 of the cassette tape, and compares it with the winding diameter values R1 and R2 of the magnetic tape 1. By doing so, the vicinity of the end and start end of the magnetic tape 1 can be detected.

In FIG. 5, the parts surrounded by broken lines, namely, the magnetic tape running speed detection circuit 5, the magnetic tape winding diameter calculation circuit 10, and the magnetic tape winding diameter target value output circuit 1
1. The magnetic tape winding diameter difference detection circuit 12, the winding diameter difference tolerance output circuit 13, and the target value detection circuit 14 can be configured as one IC, and can also be configured as microcomputer software.

When configured using microcomputer software, the actual processing contents of the magnetic tape winding diameter calculating circuit 10 shown in FIG. 5 are shown in FIG. 6 and (Equation 1) to (Equation 4).
Explain using.

The running speed of the magnetic tape 1 is Vt, the winding diameter of the magnetic tape 1 wound around the supply reel 2 side is R1, and the winding diameter of the magnetic tape 1 wound around the take-up reel 3 side is R.
2, the rotation period T1 of the supply reel 2 and the rotation period T2 of the take-up reel 3 are respectively,

[0015]

[Math 1]

[0016]

[Math 2]

It is expressed by the formula: Here, π represents pi. If we transform the formulas (Math. 1) and (Math. 2), we get

00
18]

[Math 3]

[0019]

[Math 4]

It can be expressed as follows. (Math. 3),
Equation (4) can be calculated from the value of the running speed Vt of the magnetic tape 1 and the rotation period T1, T2 of the supply reel 2 and take-up reel 3. This means that the winding diameters R1 and R2 of the tape 1 can be calculated. From this, the magnetic tape winding diameter calculation circuit 10 uses (Equation 3) and (Equation 4) to calculate the value of the running speed Vt of the magnetic tape 1 and the rotation period values of the supply reel 2 and take-up reel 3. From this, the winding diameter values R1 and R2 of the magnetic tape 1 wound on the supply reel 2 side and the take-up reel 3 side are calculated, and the calculated results are outputted as digital values to the magnetic tape winding diameter difference calculation circuit 12. Become.

[0021]

However, in the conventional magnetic tape running device as described above, the running speed of the magnetic tape 1 must always be detected by the magnetic tape running speed detection circuit 5; When changing the running speed from a constant running speed to an arbitrary speed and running the magnetic tape 1 at a variable speed, it takes a certain amount of time to reach the desired speed, and during this time the magnetic tape The running speed detection circuit 5 is temporarily unable to detect the running speed of the magnetic tape 1. Further, even if for some reason a heavy load is applied to the magnetic tape 1 while the magnetic tape 1 is constantly running at a certain speed and the speed fluctuates, the running speed of the magnetic tape 1 cannot be detected. In this way, the fact that the running speed cannot be detected means that it becomes impossible to calculate the winding diameters R1 and R2 of the magnetic tape 1, and it becomes impossible to detect the vicinity of the end and start end of the magnetic tape 1.

By the way, the process of detecting the vicinity of the end or start end of a magnetic tape is performed when the magnetic tape approaches the end or start end while the magnetic tape is running at a high speed such as FF/REW. It is generally used in systems that reduce the speed and ultimately stop the running of the magnetic tape to prevent damage to the magnetic tape.

Therefore, if the magnetic tape 1 is FF/R
While running at a high speed such as EW, the running speed cannot be detected due to the above reasons, and if the magnetic tape 1 really enters the end or start without being able to detect the end or start of the magnetic tape 1, the magnetic This would cause great damage to the tape 1 itself, and in the worst case, the magnetic tape 1 would be unwound. In addition, in a magnetic tape running device using a rotating head system, not only the magnetic tape 1 is damaged, but the magnetic tape 1 is wound around the rotating head with a force greater than normal, which causes major damage to the head itself. It had some problems.

In view of the above-mentioned conventional problems, the present invention improves reliability with a simple configuration, and maintains the running position (near the end and start end) of the magnetic tape no matter what speed the magnetic tape is running. The purpose of this invention is to provide a magnetic tape running device that can perform detection reliably.

[0025]

Means for Solving the Problems In order to solve the above problems, a magnetic tape running device of the present invention is provided in a magnetic recording/reproducing device, which includes a magnetic tape driving means for running a magnetic tape at a variable speed, and a magnetic tape driving means for winding the magnetic tape. A period of a frequency signal proportional to the rotation speed of a take-up reel for taking the magnetic tape and a supply reel for pulling out and supplying the magnetic tape is measured, and a digital value corresponding to the rotation speed of the take-up reel and the supply reel is measured. and the total area of the magnetic tape wound around both the reel parts based on the output value of the reel period measuring means and information on the arbitrarily settable running speed of the magnetic tape in the magnetic tape drive means. magnetic tape total area calculation means for calculating the total area of the magnetic tape and outputting a digital value corresponding to the total area of the magnetic tape; storage means for storing the output value of the magnetic tape total area calculation means as a memory; A magnetic tape winding diameter that calculates the winding diameter of the magnetic tape wound around both the reel parts from the output value of the means and the output value of the reel period measuring means, and outputs a digital value corresponding to the winding diameter of the magnetic tape. a calculating means, a magnetic tape winding diameter target value outputting means for outputting an arbitrarily settable target value of the winding diameter of the magnetic tape as a digital value, and an output value of the magnetic tape winding diameter calculating means and the magnetic tape winding diameter target value. a magnetic tape winding diameter difference detection means that calculates the difference between the output value of the value output means and outputs it as a digital value; and a magnetic tape winding diameter that outputs an arbitrarily settable allowable value for the winding diameter difference of the magnetic tape as a digital value. a target value for outputting a target value detection signal to the outside only when the output value of the magnetic tape winding diameter difference output means is within the range of the output value of the magnetic tape winding diameter difference output means; It is equipped with a detection means.

Further, in the present invention, the magnetic tape total area calculation means and the storage means are configured to first drive the magnetic tape at a predetermined speed after the cassette tape is loaded into the magnetic tape drive means. The total area of the magnetic tape is calculated and stored during a constant running period of time, and after the total area of the magnetic tape is calculated and stored, the cassette tape is removed from the magnetic tape drive means. At certain fixed intervals until
The calculation of the winding diameter of the magnetic tape wound around both the reel parts is repeated from the output value from the storage means and the output value of the reel period measurement means, and the storage operation of the storage means is stopped and the magnetic tape is The vehicle is configured to hold the values stored in the storage means during a period when the vehicle travels at a constant speed.

[0027] Further, in the present invention, the target value of the winding diameter of the magnetic tape is arbitrarily set by the magnetic tape winding diameter target value output means, and the target value detection signal outputted from the target value detection means is read. , which is configured to be able to detect any running position of the magnetic tape.

[0028]

[Operation] With the above configuration, the present invention first runs the magnetic tape at a certain speed for a certain period of time, and during that time the total area of the magnetic tape wound on the supply reel side and the take-up reel side is calculated by the device. It is calculated internally and stored in memory. Next, while retaining the memorized value,
Measures the rotation period of the supply reel and take-up reel,
The winding diameter of the magnetic tape wound around both reel parts is calculated from the measured rotation period of both reels and the total area value of the magnetic tape stored and held in the memory, and compared with the target winding diameter value. By repeating this operation at regular intervals, the running position (near the end or start end) of the magnetic tape can be reliably detected no matter what speed the magnetic tape is running.

Furthermore, when the above detection process is performed by a microcomputer or the like, when calculating the total area of the magnetic tape, the operation of detecting the running speed of the magnetic tape by the magnetic tape running speed detection means and the operation of detecting the running speed of the magnetic tape by the magnetic tape running speed detecting means, The total area calculation means calculates the total area of the magnetic tape wound on the supply reel side and the take-up reel side, and the storage means stores the calculated total area of the magnetic tape, and the total area of the magnetic tape is calculated. After calculation and memorization are completed,
Since only the operation of reading the total area of the magnetic tape from the storage means is performed, the program can be operated without placing any burden on the program.

[0030]

[Example] The following is an example of the present invention.
This will be explained in detail with reference to FIGS. 3 and 4.

FIG. 1 shows a block diagram of the entire magnetic tape running device according to an embodiment of the present invention. In FIG. 1, 1 is a magnetic tape, 2 is a supply reel, 3 is a take-up reel, 4 is a magnetic tape drive circuit that stably drives the magnetic tape 1 at a variable speed, and 5 is a magnetic tape 1 from the magnetic tape drive circuit 4. It is detected whether or not the running speed of the magnetic tape 1 falls within the running speed range of the magnetic tape that is set when changing the running speed, and when the running speed of the magnetic tape 1 falls within the running speed range.
A magnetic tape running speed detection circuit outputs the running speed of the magnetic tape 1 as a digital value by counting the cycle of the running speed signal using an internal clock; 6 is a cycle of a frequency signal proportional to the rotational speed of the supply reel 2; A reel period measuring circuit 7 measures the period of a frequency signal proportional to the rotational speed of the take-up reel 3 and outputs a digital value corresponding to the rotational speed. A reel period measuring circuit 8 calculates the area S1 of the magnetic tape 1 wound on the supply reel 2 side and the area S1 on the take-up reel 3 side from the output value of the magnetic tape running speed detection circuit 5 and the output values of the reel period measuring circuits 6 and 7. A magnetic tape total area calculation circuit calculates the area S2 of the wound magnetic tape 1 and outputs the sum of the areas S1 and S2 as a digital value; 9 is an output value of the magnetic tape total area calculation circuit 8; A memory 10 stores the winding diameter R1 of the magnetic tape 1 wound on the supply reel 2 side and the magnetic tape 1 wound on the take-up reel 3 side from the output values of the memory 9 and the output values of the reel period measuring circuits 6 and 7. a magnetic tape winding diameter calculation circuit that calculates a winding diameter R2 of the winding diameter R2 and outputs a digital value corresponding to the winding diameter R1, R2;
1 is a magnetic tape winding diameter target value output circuit that outputs a digital value of a target value of the winding diameter of the magnetic tape 1, which can be set arbitrarily;
12 is a magnetic tape winding diameter difference detection circuit which calculates the difference between the output value of the magnetic tape winding diameter calculation circuit 10 and the output value of the magnetic tape winding diameter target value output circuit 11 and outputs the difference as a digital value; 13;
14 is a winding diameter difference tolerance output circuit that outputs the arbitrarily settable winding diameter difference tolerance of the magnetic tape 1 as a digital value, and 14 is a winding diameter difference tolerance output circuit in which the output value of the magnetic tape winding diameter difference detection circuit 12 is output. 13 is a target value detection circuit that outputs a signal to the outside only when the output value is within the range; 15 is a target value detection circuit 1;
This is the target value detection signal output from 4.

2 and 3 are block diagrams showing the actual operation of the magnetic tape running device according to the embodiment of the present invention, and FIG. 4 shows the winding diameter R1 of the magnetic tape 1 of the magnetic tape running device according to the embodiment of the present invention. This figure shows a diagram specifically illustrating a method of calculating R2. In FIG. 4, 21 is the hub of the cassette tape attached to the supply reel 2 side, 22
is the hub of the cassette tape attached to the take-up reel 3 side.

The operation of the magnetic tape transport system of this embodiment constructed as described above will be explained below with reference to FIGS. 1, 2, 3, and 4.

When the cassette tape is first loaded into the magnetic tape drive circuit 4, the block diagram of FIG. 1 actually becomes the state shown in FIG. The vehicle starts traveling at a set speed Vt0 in a certain direction. When the magnetic tape 1 starts running, the magnetic tape running speed detection circuit 5 detects the speed V.
An upper limit value and a lower limit value are arbitrarily set as a permissible range with t0 as the center, and it is detected whether the running speed of the magnetic tape 1 is within the permissible range of the speed Vt0. When the running speed of the magnetic tape 1 falls within the permissible range of Vt0, the cycle of the running speed signal of the magnetic tape 1 is calculated by counting the internal clock, and the running speed of the magnetic tape 1 is calculated as the running speed Vt0 of the magnetic tape 1 in a digital value. It is output to the tape total area calculation circuit 8.

Further, as the magnetic tape 1 runs, the supply reel 2 and the take-up reel 3 rotate at a certain speed, and the reel period measuring circuits 6 and 7 detect the supply reel 2 and the take-up reel 3.
and the period of the frequency signal proportional to the rotational speed of the take-up reel 3, and outputs a digital value corresponding to the period to the magnetic tape total area calculation circuit 8. The magnetic tape total area calculation circuit 8 calculates the supply reel 2 based on the running speed of the magnetic tape 1 from the magnetic tape running speed detection circuit 5 and the reel cycle from the reel cycle measuring circuits 6 and 7.
The area S1 of the magnetic tape 1 wound around the side and the area S2 of the magnetic tape 1 wound around the take-up reel 3 side are calculated, and the total area value of the magnetic tape 1, which is the sum of the areas S1 and S2, is calculated as a digital value. is output to the memory 9. Furthermore, in the memory 9, a magnetic tape total area calculation circuit 8
The total area value of the magnetic tape 1 from 1 to 3 is stored and retained.

After the calculation and storage of the total area of the magnetic tape 1 is completed, the state is switched from FIG. 2 to that shown in FIG. 3, and the magnetic tape 1 is run at an arbitrary speed in the direction of arrow a or b. When the magnetic tape 1 runs at a given speed, the supply reel 2 and take-up reel 3 rotate at a certain speed, and the reel period measuring circuits 6 and 7 measure a frequency proportional to the rotational speed of the supply reel 2 and take-up reel 3. The period of each signal is measured, and a digital value corresponding to the period is output to the magnetic tape winding diameter calculation circuit 10. In addition, the magnetic tape winding diameter calculating circuit 10 reads out the total area of the magnetic tape 1 stored and held in the memory 9, and at the same time reads the magnetic tape wound around the supply reel 2 side based on the reel period from the reel period measuring circuits 6 and 7. 1 and the square value R22 of the winding diameter of the magnetic tape 1 wound on the take-up reel 3 side, and the calculated R12 and R22 are each converted into digital values by a magnetic tape winding diameter difference detection circuit. 12 is output.

Next, the magnetic tape winding diameter difference detection circuit 12 calculates R12 calculated by the magnetic tape winding diameter calculation circuit 10.
. It is output to the target value detection circuit 14. At this time, the winding diameter difference tolerance output circuit 13 outputs a digital value of an arbitrarily settable tolerance within which the difference between the winding diameter values R12, R22 of the magnetic tape 1 and the target value should be within. It is output to the target value detection circuit 14.

Then, the target value detection circuit 14 detects the difference between R12 and R22 from the magnetic tape winding diameter difference detection circuit 12 and the winding diameter target value, and the tolerance of the winding diameter difference from the winding diameter difference tolerance output circuit 13. The winding diameters R12, R22 of the magnetic tape 1 reach the target winding diameter value only when the difference between the R12, R22 and the target winding diameter value is within the tolerance value of the winding diameter difference. Therefore, the target value detection signal 15 is outputted to the outside.

As described above, the operation shown in FIG. 3 is repeated at certain predetermined intervals until the cassette tape is taken out from the magnetic tape drive circuit 4, and as a result, the magnetic tape 1 wound around the supply reel 2 side is The square value R12 of the winding diameter and the square value R22 of the winding diameter of the magnetic tape 1 wound around the take-up reel side 3 can be calculated in real time. In addition, the magnetic tape winding diameter target value output circuit 11 sets the target winding diameter value of the magnetic tape 1 to the square value r12, r22 of the hub diameter of the cassette tape, and sets the winding diameter value R12, R22 of the magnetic tape 1 as the square value of the hub diameter of the cassette tape. By comparing these, it is possible to detect the vicinity of the end and start end of the magnetic tape 1.

Furthermore, in this case, the running speed of the magnetic tape 1 is detected in the state shown in FIG. 2 in which the total area of the magnetic tape 1 is first calculated after the cassette tape is loaded into the magnetic tape drive circuit 4. After switching to the state shown in FIG. 3, the reading operation from the memory 9 is performed without looking at the information on the running speed of the magnetic tape 1 until the cassette tape is taken out from the magnetic tape drive circuit 4. By doing this, the running position of the magnetic tape 1 (near the end or start end) is detected.
This is effective for detection processing near the end and start of.

As described above, according to this embodiment, the magnetic tape is first run at a certain speed for a certain period of time, and during that time the total area of the magnetic tape wound on the supply reel side and the take-up reel side is is calculated inside the device and stored in memory. Next, while retaining the memorized value,
Measures the rotation period of the supply reel and take-up reel,
The winding diameter of the magnetic tape wound around both reel parts is calculated from the measured rotation period of both reels and the total area value of the magnetic tape stored and held in the memory, and compared with the target winding diameter value. By repeating this operation at certain regular intervals, no matter what speed the magnetic tape is running, the running position of the magnetic tape (near the end or start end) can be maintained.
can be reliably detected.

In FIG. 1, the portions surrounded by thick broken lines include the magnetic tape running speed detection circuit 5, the magnetic tape total area calculation circuit 8, the memory 9, the magnetic tape winding diameter calculation circuit 10, and the magnetic tape winding diameter target value. The output circuit 11, the magnetic tape winding diameter difference detection circuit 12, the winding diameter difference tolerance output circuit 13, and the target value detection circuit 14 can be configured as one IC, and can also be configured as microcomputer software. , the setting of the target winding diameter value of the magnetic tape 1 from the magnetic tape winding diameter target value output circuit 11 and the tolerance value of the winding diameter difference from the winding diameter difference tolerance value output circuit 13 can be handled only by software. This eliminates the need for adding or changing hardware.

When constructed using microcomputer software, the actual processing contents in the magnetic tape total area calculation circuit 8 and magnetic tape winding diameter calculation circuit 10 shown in FIG. 1 are shown in FIG. 4 and (Equation 5) to (Equation 17). Explain using.

First, regarding the magnetic tape total area calculation circuit 8, the magnetic tape 1 is moved at a speed of Vt0 by arrow a or b.
The winding diameter of the magnetic tape 1 wound on the supply reel 2 side at that time is R1, the winding diameter of the magnetic tape 1 wound on the take-up reel 3 side is R2, and the rotation period of the supply reel 2 is T1. , the rotation period of the take-up reel 3 is T
2, S1 in FIG. 4 is

[0045]

[Math 5]

The formula S2 is

[0047]

[Math 6]

It is expressed by the formula: Here, r1 and r2 represent the hub diameter of the cassette tape attached to the supply reel 2 side and the hub diameter of the cassette tape attached to the take-up reel 3 side, respectively, and π represents the circumference. Furthermore, if S is the total area value of the magnetic tape 1 that is the sum of S1 and S2, then S is

[
0049

[Math 7]

The formula is as follows. By the way, since the magnetic tape 1 is running at the speed Vt0, R1 and R2 are respectively,

[0051]

[Math. 8]

[0052]

[Math. 9]

It is expressed as follows. Substituting the equations (8) and (9) into the equation (7) and rearranging the equation, we get

[
0054

[Math. 10]

The formula is obtained, and by slightly transforming the formula (10),

[0056]

[Math. 11]

It can be expressed as follows. here,
The left side of this equation (11) is the hub 21 of the cassette tape.
. This means that it can be calculated from the square value of velocity Vt02. From this, the magnetic tape total area calculation circuit 8 uses (Equation 11) to calculate the value of the running speed Vt0 of the magnetic tape 1 and the reel period measurement circuits 6, 7.
The total area of the magnetic tape 1 including the areas of the hubs 21 and 22 of the cassette tape is calculated from the values of the reel rotation periods T1 and T2 from , and the calculated result is outputted to the memory 9 as a digital value. Become. This calculated area remains completely unchanged and constant regardless of the running position of the magnetic tape 1 from the time the cassette tape is loaded into the magnetic tape drive circuit 4 until it is taken out, and this area is stored in the memory. 9 and calculates the winding diameter of the magnetic tape 1 from the stored and held area is the next magnetic tape winding diameter calculation circuit 10.

Next, regarding the magnetic tape winding diameter calculation circuit 10, the equations (8) and (9) are modified,

[0059]

[Math. 12]

[0060]

[Math. 13]

By substituting the formulas individually into (Equation 11) and rearranging the formulas,

[0062]

[Math. 14]

[0063] and

[0064]

[Math. 15]

The running speed Vt of the magnetic tape 1 is given by the equation:
An expression that does not contain 0 is calculated. Calculated (Math 1
4), (Equation 15) is transformed a little, and becomes

006
6]

[Math. 16]

[0067]

[Math. 17]

It can be expressed as follows. In the equations (16) and (17), the part surrounded by curly brackets on the right side corresponds to the area stored and held in the memory 9, and T12 and T22 are the areas of the supply reel 2 and the take-up reel. 3. Therefore, from the area value from the memory 9 and the reel rotation period value from the reel period measuring circuits 6 and 7, the winding of the magnetic tape 1 wound around the supply reel 2 side can be determined. This means that the square value R12 of the diameter and the square value R22 of the winding diameter of the magnetic tape 1 wound on the take-up reel 3 side can be calculated. From this, in the magnetic tape winding diameter calculation circuit 10, (Equation 1
6) and (Equation 17), the magnetic tape 1 wound around the supply reel 2 side can be calculated from the area value from the memory 9 and the reel rotation periods T1 and T2 values from the reel period measurement circuits 6 and 7. The square value R12 of the winding diameter and the square value R of the winding diameter of the magnetic tape 1 wound on the take-up reel 3 side
22 is calculated, and the calculated result is outputted as a digital value to the magnetic tape winding diameter difference detection circuit 12.

[0069]

[Effects of the Invention] As described above, the present invention first runs a magnetic tape at a certain speed for a certain period of time.
During this time, the total area of the magnetic tape wound on the supply reel side and the take-up reel side is calculated inside the device and stored in the memory. Next, while holding the memorized values, measure the rotation periods of the supply reel and take-up reel, and use the measured rotation periods of both reels and the total area of the magnetic tape stored and held in memory to calculate the area of both reels. The winding diameter of the magnetic tape wound around is calculated and compared with the target winding diameter value. By repeating this operation at regular intervals, the running position of the magnetic tape (near the end or start end) can be ensured no matter what speed the magnetic tape is running.
Detection can be performed, and it is possible to obtain the effect of reliably preventing damage to the magnetic tape, head, etc. at the end and start end of the magnetic tape, especially during high-speed running such as FF/REW.

Furthermore, in the case where the above-mentioned detection processing is performed by a microcomputer or the like, when calculating the total area of the magnetic tape, the operation of detecting the running speed of the magnetic tape by the magnetic tape running speed detection means and the operation of detecting the running speed of the magnetic tape by the magnetic tape running speed detecting means, The total area calculation means calculates the total area of the magnetic tape wound on the supply reel side and the take-up reel side, and the storage means stores the calculated total area of the magnetic tape, and the total area of the magnetic tape is calculated. After calculation and memorization are completed,
Since only the operation of reading the total area of the magnetic tape from the storage means is performed, the program can be operated without placing any burden on the program. Furthermore, since the device can be configured using digital circuits and software programs, it can be easily integrated into an LSI, and the number of parts used can be reduced, resulting in an inexpensive and simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the entire magnetic tape running device in an embodiment of the present invention.

FIG. 2 is a block diagram showing the actual operation of the magnetic tape running device in the embodiment of the present invention.

FIG. 3 is a block diagram showing the actual operation of the magnetic tape running device in the embodiment of the present invention.

FIG. 4 is a diagram for explaining the winding diameter calculation of the magnetic tape of the magnetic tape running device in the embodiment of the present invention.

[Figure 5] Block diagram of a conventional magnetic tape running device

FIG. 6 is a diagram for explaining calculation of the winding diameter of a magnetic tape in a conventional magnetic tape running device.

[Explanation of symbols]

1 Magnetic tape 2 Supply reel 3 Take-up reel 4 Magnetic tape drive circuit 5 Magnetic tape running speed detection circuit 6 Supply reel side reel period measurement circuit 7 Take-up reel side reel period measurement circuit 8 Magnetic tape total area calculation circuit 9 Memory 10 Magnetism Tape winding diameter calculation circuit 11 Magnetic tape winding diameter target value output circuit 12 Magnetic tape winding diameter difference detection circuit 13 Winding diameter difference tolerance output circuit 14 Target value detection circuit 15 Target value detection signal 21 Cassette tape hub attached to the supply reel side 22 Cassette tape hub attached to take-up reel side

Claims (3)

[Claims] 1. A magnetic recording and reproducing apparatus, comprising: a magnetic tape drive means for running a magnetic tape at a variable speed; a take-up reel for winding the magnetic tape; and a supply reel for drawing out and supplying the magnetic tape. reel period measuring means for measuring the period of a frequency signal proportional to the rotational speed and outputting a digital value corresponding to the rotational speed of the take-up reel and the supply reel; and an output value of the reel period measuring means and the magnetic field. a magnetic tape that calculates the total area of the magnetic tape wound around both the reel parts from information on the running speed of the magnetic tape, which can be arbitrarily set in a tape drive means, and outputs a digital value corresponding to the total area of the magnetic tape; tape total area calculation means; storage means for storing the output value of the magnetic tape total area calculation means as a memory; and winding around the two reel parts based on the output value of the storage means and the output value of the reel period measurement means. magnetic tape winding diameter calculating means for calculating the winding diameter of the magnetic tape and outputting a digital value corresponding to the winding diameter of the magnetic tape; a magnetic tape winding diameter target value output means for outputting a magnetic tape winding diameter target value; and a magnetic tape winding system for calculating the difference between the output value of the magnetic tape winding diameter calculation means and the output value of the magnetic tape winding diameter target value output means and outputting it as a digital value. a diameter difference detection means, a magnetic tape winding diameter difference tolerance output means for outputting an arbitrarily settable tolerance value for the winding diameter difference of the magnetic tape as a digital value, and an output value of the magnetic tape winding diameter difference detection means that 1. A magnetic tape running device comprising target value detection means for outputting a target value detection signal to the outside only when the output value is within the range of the output value of the magnetic tape winding diameter difference tolerance output means. 2. The magnetic tape total area calculation means and the storage means are configured such that after the cassette tape is loaded into the magnetic tape drive means, the magnetic tape is initially kept at a certain speed for a predetermined period of time. The total area of the magnetic tape is calculated and stored during the period when the cassette tape is running, and after the total area of the magnetic tape is calculated and stored, until the cassette tape is taken out from the magnetic tape drive means. The winding diameter of the magnetic tape wound around both the reel portions is calculated repeatedly from the output value from the storage means and the output value from the reel cycle measuring means at a predetermined period, and the winding diameter is stored in the storage means. 2. The magnetic tape running device according to claim 1, wherein the magnetic tape running device holds the value stored in the storage means during a period when the magnetic tape is running at a constant speed while the operation is stopped. 3. By arbitrarily setting a target value for the winding diameter of the magnetic tape by the magnetic tape winding diameter target value outputting means and reading the target value detection signal output from the target value detection means, the magnetic 2. The magnetic tape running device according to claim 1, wherein an arbitrary running position of the tape can be detected.