JPH0877655A - Speed-detecting apparatus - Google Patents

Abstract

PURPOSE: To accurately calculate a correct running speed of a tape by a rotating speed of a single reel, by counting a count of pulses generated proportionally to the number of revolutions of the reel and detecting the diameter of the reel of the tape. CONSTITUTION: The rotation period of the reel is detected by a period detector 31 from pulse signals output by a signal generator 30 in proportion to the rotating speed of the reel. The diameter of the reel of a tape 1 is obtained by a diameter detector 32 from the rotation period and a predetermined running speed Vo of the magnetic tape 1. A diameter change calculator multiplies the counted number of pulses counted by a counter 33 by the thickness of the tape 1, thereby calculating a changing amount of the diameter of the reel of the tape 1. The changing amount is added to the reel diameter by an adder 35. A reference value for the period is calculated by a reference period calculator 36 from the added value and the speed of the predetermined tape 1 and fed to a speed calculator 37, where the running speed of the tape 1 is calculated with the use of the output of the cycle detector 31 and the speed of the speed of the predetermined tape 1. Accordingly, the correct reel diameter and the correct running speed of the tape can be obtained only from a rotating speed of a single reel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed detecting device for detecting the running speed of a tape medium wound on a reel.

[0002]

2. Description of the Related Art In a magnetic recording / reproducing apparatus such as a video tape recorder, the traveling speed of a magnetic tape is detected and a rotating cylinder is rotated at a speed corresponding to the traveling speed of the magnetic tape to keep the relative speed of the magnetic tape and the head constant. Keeping devices have been devised. Therefore, a speed detecting means for accurately detecting the running speed of the magnetic tape has been proposed as disclosed in JP-A-1-294257.

FIG. 2 is a block diagram showing the structure of a conventional speed detecting device. A conventional speed detecting device will be briefly described below.

In FIG. 2, a magnetic tape 1 is wound around a reel 2 and a reel 3 without slack.

The central controller 60 controls the rotational speeds of the capstan 10 and the electric motor 25. A capstan roller 11 is attached on the rotation shaft of the capstan 10, a pinch roller 12 has a mechanism that can be attached to and detached from the capstan roller 11, and the magnetic tape 1 can be sandwiched between the pinch roller 12 and the capstan roller 11. When the magnetic tape 1 is transported at a constant speed, the magnetic tape 1 is sandwiched between the capstan roller 11 and the pinch roller 12, and the capstan 1
The driving force of 0 is transmitted to the magnetic tape 1, and the magnetic tape 1 is transported. The capstan 10 is rotated at a constant speed for a fixed time according to a command from the central controller 60, and the magnetic tape 1 is transported at a constant speed, for example, a standard reproduction speed. At this time, the electric motor 25
Applies a constant torque to the reel 2 or 3 so that the magnetic tape 1 does not sag, and winds the magnetic tape. The driving force of the electric motor 25 is switched to the reel 2 or 3 by the drive switching device 27.

Further, the electric motor 25 rotates at an arbitrary speed according to a command from the central control unit 60, and transfers the magnetic tape 1 at an arbitrary speed. At this time, the pinch roller 12 is separated from the capstan roller 11, and the driving force of the capstan 10 is not transmitted to the magnetic tape 1.

First, the operation of the speed detecting device when the magnetic tape 1 is transported at a constant speed for a fixed time will be described.

The magnetic tape 1 is sandwiched between a capstan roller 11 and a pinch roller 12 mounted on the rotating shaft of a capstan 10. The capstan 10 rotates at a constant speed and transfers the magnetic tape 1 at a standard reproduction speed. The reels 2 and 3 are wound so that the magnetic tape 1 is not loosened in accordance with the running speed and the transport direction of the magnetic tape 1.

A signal generator 30 outputs a pulse signal having a frequency proportional to the rotation speed to each of the reels 2 and 3.
And 40 are attached. The cycle detector 31 detects the cycle of the pulse signal output from the signal generator 30.
Further, the cycle detector 41 detects the cycle of the pulse signal output from the signal generator 40. The tape speed calculation circuit 42 calculates the sum of the cycle output by the cycle detector 31 and the cycle output by the cycle detector 41. The storage circuit 43 stores the sum of cycles calculated by the tape speed calculation circuit 42.

The period sum is stored in the storage circuit 43,
After a certain period of time has passed, the central controller 60 commands the electric motor 25 to transfer the magnetic tape 1 at an arbitrary speed.

The operation of the speed detecting device when the magnetic tape 1 has an arbitrary speed will be described below. The pinch roller 12 is separated from the capstan roller 11, and the electric motor 25 rotates at an arbitrary speed. The magnetic tape 1 is transported at an arbitrary speed in accordance with the rotation of the electric motor 25, and the tape speed calculation circuit 42 calculates the sum of the cycles output by the signal generators 31 and 41 as when the capstan 10 operates. The division circuit 44 calculates the ratio of the cycle sum output from the tape speed calculation circuit 42 and the cycle sum stored in the storage circuit 43 to calculate the speed ratio with the standard reproduction speed.

[0012]

However, in the above-mentioned conventional structure, it is necessary to detect the rotation speeds of the two reels in order to detect the traveling speed of the magnetic tape, and it is impossible to reduce the number of parts. Or, there is a problem that it cannot be applied to the case of a single reel.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a speed detecting device capable of accurately detecting the running speed of a magnetic tape only by the rotation speed of a single reel. To do.

[0014]

As a structure for attaining these objects, a speed detecting device comprises a reel around which one end of a tape medium is wound, and a first speed for transporting the tape medium at a predetermined constant speed. Tape drive means, and second tape drive means for transporting the tape medium at an arbitrary speed,
Signal generating means for outputting a pulse signal having a frequency proportional to the rotation speed of the reel, cycle detecting means for detecting the cycle of the pulse signal output by the signal generating means, and the first tape driving means are operated. Then, the winding diameter of the tape medium wound on the reel is determined from the output of the cycle detecting means during the operation of the central control means for operating the second tape driving means and the first tape driving means. The winding diameter detecting means for detecting, the counting means for counting the number of pulses of the pulse signal output from the signal generating means during the operation of the second tape driving means, and the output of the counting means are multiplied by a predetermined coefficient. Then, the winding diameter change calculating means for calculating the amount of change in the winding diameter, the winding diameter adding means for adding the output of the winding diameter detecting means and the output of the winding diameter change calculating means, and the output of the winding diameter adding means. Proportional to A reference cycle calculating means for calculating a reference value inversely proportional to a predetermined constant speed, and the cycle detecting means in proportion to the predetermined constant speed and the output of the reference cycle calculating means during the operation of the second tape driving means. And a speed calculation means for outputting a value that is inversely proportional to the output of.

[0015]

With the above-described structure, the present invention makes it possible to calculate the amount of change in the winding diameter by counting the number of pulses of the pulse signal while the running speed of the tape medium changes, and to detect the accurate winding diameter. The reference cycle of the pulse signal is obtained from the accurate winding diameter and the predetermined tape speed, and the running speed of the tape medium can be accurately determined by the predetermined tape speed, the reference cycle, and the detected pulse signal cycle. Can be detected.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings using a video tape recorder as an example.

FIG. 1 is a block diagram showing the structure of a speed detecting device according to an embodiment of the present invention. In FIG. 1, the same components as those of the conventional speed detecting device shown in FIG. 2 are designated by the same reference numerals and their description is omitted.

In FIG. 1, the winding diameter detector 32 detects the winding diameter of the magnetic tape 1 wound on the reel 3 according to the cycle output from the cycle detector 31.

The counter 33 counts the number of pulses of the pulse signal output from the signal generator 30. The winding diameter change calculator 34 multiplies the count value of the counter 33 and the thickness of the magnetic tape 1 to calculate the amount of change in the winding diameter of the magnetic tape 1.
The winding diameter adder 35 adds the output of the winding diameter detector 32 and the output of the winding diameter change calculator 34. The reference period calculator 36 calculates a reference value based on the winding diameter output from the winding diameter adder 35 and the predetermined speed of the magnetic tape 1. The speed calculator 37 calculates the running speed of the magnetic tape 1 using the output of the reference cycle calculator 36, the output of the cycle detector 31, and the predetermined speed of the magnetic tape 1.

The operation of the speed detecting device constructed as above will be described. The central controller 60 controls the rotation speeds of the capstan 10 and the electric motor 25. The capstan roller 11 is mounted on the rotation shaft of the capstan 10, and the pinch roller 12 is the capstan roller 1.
1, the magnetic tape 1 can be sandwiched between the pinch roller 12 and the capstan roller 11. When the magnetic tape 1 is transported at a constant speed, the magnetic tape 1 is sandwiched between the capstan roller 11 and the pinch roller 12, and the driving force of the capstan 10 is transmitted to the magnetic tape 1.
The magnetic tape 1 is transferred. The capstan 10 is rotated at a constant speed for a fixed time according to a command from the central controller 60, and the magnetic tape 1 is transported at a constant speed, for example, a standard reproduction speed.
At this time, the electric motor 25 applies a constant torque to the reel 3 so as to prevent the magnetic tape 1 from slackening, and winds the magnetic tape 1.

Further, the electric motor 25 rotates at an arbitrary speed according to a command from the central control unit 60, and transfers the magnetic tape 1 at an arbitrary speed. At this time, the pinch roller 12 is separated from the capstan roller 11, and the driving force of the capstan 10 is not transmitted to the magnetic tape 1.

First, the operation of the speed detecting device when the magnetic tape 1 is transported at the standard reproduction speed V0 for a fixed time will be described.

The magnetic tape 1 is sandwiched between a capstan roller 11 and a pinch roller 12 mounted on the rotating shaft of the capstan 10. The capstan 10 rotates at a constant speed and transfers the magnetic tape 1 at a standard reproduction speed V0.
The reel 3 is wound according to the traveling speed and the transport direction of the magnetic tape 1 so that the magnetic tape 1 is not loosened. The cycle detector 31 detects the cycle of the pulse signal output from the signal generator 30. The winding diameter detector 32 detects the winding diameter R0 of the magnetic tape 1 wound around the reel 3 based on (Equation 1) while the magnetic tape 1 is running at the standard reproduction speed V0.

[0024]

[Equation 1]

The winding diameter detection circuit 32 detects the winding diameter, and after a certain time has passed, the central controller 60 instructs the electric motor 25 to
A command is issued to transfer the magnetic tape 1 at an arbitrary speed.

The operation of the speed detecting device when the magnetic tape 1 is transported at an arbitrary speed will be described below.

The pinch roller 12 is the capstan roller 1
Separated from 1, the electric motor 25 rotates at an arbitrary speed. The magnetic tape 1 is transported at an arbitrary speed according to the rotation of the electric motor 25. The counter 33 counts the number N of pulses of the pulse signal output from the signal generator 30. The winding diameter change calculator 34 uses the number N of pulses counted by the counter 33, the thickness K of the magnetic tape 1 given in advance, and the number Z of pulses output per rotation of the reel 3 (Equation 2). Is used to calculate the change amount ΔR of the winding diameter.

[0028]

[Equation 2]

The roll diameter adder 35 adds the roll diameter R0 detected by the roll diameter detector 32 and the roll diameter change amount ΔR calculated by the roll diameter change calculator 34 to correct the roll diameter. Reference period calculator 36
On the basis of (Equation 3), the period Ts of the pulse signal detected when the tape velocity is the standard reproduction velocity V0 with the corrected winding diameter is calculated, and this period Ts is used as the reference period.

[0030]

(Equation 3)

The speed calculator 37 calculates the running speed Vn of the magnetic tape 1 from (Equation 4) using the output of the reference cycle calculator 36, the standard reproduction speed V0 and the cycle Tn of the pulse signal currently detected. .

[0032]

[Equation 4]

As described above, using only one reel 3,
An accurate tape running speed can be calculated from the rotation speed of the reel 3 and the winding diameter of the magnetic tape 1 even when the running speed of the magnetic tape 1 changes from low speed to high speed or from high speed to low speed.

Further, the block 100 shown by a broken line can be realized by software processing by a microcomputer or a signal processor having an interrupt function and a timer.

Since the rotation speed of the reel 3 and the rotation speed of the electric motor 25 are proportional to each other, the rotation speed of the reel 3 may correspond to the rotation speed of the electric motor 25.

[0036]

As described above, according to the present invention, the counting means for counting the number of pulses at the transition time when the speed of the tape medium changes and the winding diameter change calculating means for calculating the change amount of the winding diameter are provided. As a result, only with the rotation speed of a single reel,
It is possible to accurately calculate the winding diameter and the tape running speed. Further, it is possible to reduce the number of reel speed detection components.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a speed detection device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional speed detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 tape medium 3 reel 15 first tape driving means 25 second tape driving means 30 signal generating means 31 cycle detecting means 32 winding diameter detecting means 33 counting means 34 winding diameter change calculating means 35 winding diameter adding means 36 reference cycle calculating Means 37 Speed calculation means 60 Central control means

Claims (1)

[Claims] 1. A reel around which one end of a tape medium is wound, a first tape drive unit for moving the tape medium at a predetermined constant speed, and a second tape for moving the tape medium at an arbitrary speed. Drive means, signal generation means for outputting a pulse signal having a frequency proportional to the rotation speed of the reel, cycle detection means for detecting the cycle of the pulse signal output by the signal generation means, and the first tape drive Of the tape medium wound on the reel from the output of the cycle detecting means during the operation of the central control means for operating the second tape drive means after the operation of the means and the first tape drive means. Winding diameter detecting means for detecting a winding diameter, counting means for counting the number of pulses of the pulse signal output from the signal generating means during operation of the second tape driving means, and the counting A winding diameter change calculating means for calculating the amount of change in the winding diameter by multiplying the output of the stage by a predetermined coefficient, and a winding diameter adding means for adding the output of the winding diameter detecting means and the output of the winding diameter change calculating means. A reference cycle calculating means for calculating a reference value proportional to the output of the winding diameter adding means and inversely proportional to the predetermined constant speed; and the predetermined constant speed and the reference during the operation of the second tape driving means. A speed calculating means for outputting a value proportional to the output of the cycle calculating means and in inverse proportion to the output of the cycle detecting means, and detecting the running speed of the tape medium during the operation of the second tape driving means. Characteristic speed detection device.