JPS6244336B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a magnetic tape device that can be used in tape recorders, video tape recorders, etc., and particularly to a magnetic tape device that shortens the time for fast winding such as fast forwarding and rewinding. Conventional configurations and their problems In recent years, tape recorders and video tape recorders have become widespread, and new models with improved performance and functionality are being developed one after another. Among these, shortening the rewinding time is a very strong need in order to quickly perform the next recording or recording. In general, the fast winding methods of magnetic tape devices can be roughly divided into two types. One is a reel stand constant rotation method, and the other is a magnetic tape constant speed transfer method. The former has a simple reel drive system, but the rotational speed of the supply reel stand and the magnetic tape transport speed at the end of winding are extremely high, so it is not possible to shorten the fast winding time too much from the viewpoint of noise and tape damage. . Therefore, many magnetic tape devices that shorten the fast winding time employ a magnetic tape constant speed transfer method. A conventional magnetic tape device will be explained with reference to the drawings. FIG. 1 is a plan view of the main parts of a conventional magnetic tape device. The magnetic tape 3 wound on the take-up reel hub 2, which engages with the supply reel stand 1 and rotates integrally, is guided by guide members 4 and 5, and engages with the take-up reel stand 6 and rotates integrally. It is wound on a rotating take-up reel hub 7. The supply reel stand 1 and the take-up reel stand 6 are each driven by a dedicated motor (not shown). The rapid winding operation of the conventional magnetic tape device constructed as described above will now be described. Since the sum of the cross-sectional areas of the tape rolls wound around both reel hubs 2 and 7 of the magnetic tape 3 is constant, π/4(R ² _S −r ² ₁ )+π/4(R ² _T −r ² ₁ )
=K ₁ (constant)... R _S ; Supply side tape roll radius r ₁ ; Both reel hub radius R _T ; Take-up side tape roll radius, so R ² _S + R ² _T = K (constant) + 2r ² ₁ ... Since the circumferential speeds of both tape rolls are equal, R _S・n _S = R _T・n _T …… n _S ; Supply reel table rotation speed n _T ; Take-up reel table rotation speed From the second and third equations, {(n _T /n _S ) ² +1}R ² _T =K+2・r ²
₁ ... The magnetic tape transfer speed V is V=2πR _T・n _T ... Therefore, by substituting the fifth equation into the sixth equation, we get now,

If the rotational drive of both reel stands 1 and 6 is controlled so that the equation [Equation] is constant, the magnetic tape transfer speed V becomes constant depending on the reel hub diameter _r1 . That is, as shown in Fig. 2 a and b, the reel hub diameter r ₁
The magnetic tape transport speed V differs depending on whether V is small or large. However, in the above configuration, in order to further shorten the fast winding time, it is necessary to increase the magnetic tape transfer speed V, but if it is increased too much, the reel table braking force at the end will be insufficient and the tape will not be gripped by the reel hub. However, there is a problem that the magnetic tape may come off. Particularly in the case of cassette type magnetic tape devices, this problem can lead to very serious defects. In order to solve this problem, attempts have been made to detect the rotation of the reel stand and detect the vicinity of the end of early winding to reduce the magnetic tape transfer speed V, but malfunctions may occur due to the various reel hub diameters _r1 . Currently, the circuits are expensive and are not practical. OBJECTS OF THE INVENTION An object of the present invention is to provide a practical magnetic tape device that can shorten the fast winding time. Structure of the Invention: A pair of reel stands that are respectively engaged with a pair of reel hubs on which a magnetic tape is wound and rotate integrally, and at least one of the pair of reel stands is driven to rotate in a direction in which the magnetic tape is wound. a pair of rotational speed detection means that respectively detect rotational speeds of the pair of reel stands;
a rotational speed comparing means for detecting that the rotational speeds of the pair of reel stands become the same; a measuring means for measuring the time τ until the rotational speeds of the pair of reel stands become the same after the start of the fast winding operation; When a fast winding operation is performed, one of the pair of reel stands rotates at a substantially constant first magnetic tape winding speed, and after the rotational speeds of the pair of reel stands become the same, ατ( 0<α<1), and a control means for controlling the reel drive means so that the reel table drive means rotates at a second magnetic tape winding speed that is smaller than the first magnetic tape speed, thereby causing a premature end of winding. The present invention is characterized in that the magnetic tape transport speed in the vicinity is reduced to solve the problem of the magnetic tape becoming loose from the grip of the reel hub at the end. DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. FIG. 3 is a block diagram of a magnetic tape device in one embodiment of the present invention. The magnetic tape 3 wound on the supply reel hub 2 that engages with the supply reel stand 1 and rotates integrally with the guide members 4 and 5
The film is wound onto a take-up reel hub 7 which is guided by the take-up reel base 6 and rotates integrally with the take-up reel stand 6.
The supply reel stand 1 is directly connected to the supply motor 8, and the take-up reel stand 6 is directly connected to the take-up motor 9. Both motors 8 and 9 are connected to respective drive circuits 1
Rotationally driven by 0 and 11. The rotation speeds of both reel stands 1 and 6 are detected by magnetic pulses recorded on the outer peripheries of both reel stands and detection heads 12 and 13, and then the rotation speed signals n _S of the supply reel stand 1 are detected by rotation speed detection circuits 14 and 15. It is converted into a rotational speed signal _nT of the take-up reel stand 6. In the arithmetic circuit 16, from both rotational speed signals n _S and n _T

[Formula] is calculated and output, and this output is compared with the reference signal 17, and the drive circuit 10 or 11 is controlled by the control circuit 18 so that the difference becomes zero, and the magnetic tape 3
is transported at a constant speed of V ₁ . Further, a measuring circuit 21 is provided as a measuring means for measuring the time τ from when the fast winding operation switch 19 is operated until the rotational speed comparison circuit 20 makes the rotational speeds n _S and n _T of both reel stands 1 and 6 the same. After measuring, α
After τ(0<α<1), the magnetic tape transfer speed becomes V ₁
It is configured to issue a command to the control circuit 18 so that V ₂ becomes smaller than . The rewinding operation of the magnetic tape device of this embodiment configured as described above will be explained. First, when the rewind operation switch 19 is pressed, the drive circuit 10 starts rotating the supply motor 8 counterclockwise, and at the same time, the measurement circuit 21 also starts operating. The rotational speeds of both reel stands 1 and 6 are detected by detection heads 12 and 13, and the rotational speed detection circuit 1
The rotational speed signals n _S and n _T from 4 and 15 are processed by the arithmetic circuit 16.

It is processed into the form: [Formula] and compared with the reference signal 17. The control circuit 18 and drive circuit 10 are controlled so that this difference becomes zero. In this way, the magnetic tape 3 is transported at a constant speed of _V1 , as shown in FIG. During winding, both reel stands 1,
When the tape roll radii on 6 become the same, the rotation speed comparison circuit 20 is activated and the time τ after operation is
is measured by the timer 21, and then ατ(0<
α<1) As time elapses, the magnetic tape transfer speed from the measuring circuit 21 to the control circuit 18 becomes smaller than V ₁ .
Since a command is issued to set the speed to _V2 , the control circuit 18 controls the drive circuit 10 so that the magnetic tape 3 is transported at a constant speed of _V2 as shown in FIG. In this way, according to this embodiment, the tape transport speed is reduced after the time τ to ατ until the rotations of both reel stands 1 and 6 become the same, so the tape transport speed is reduced near the end of unwinding. You can. Furthermore, as shown in FIGS. 5a and 5b, it is possible to reduce the tape transport speed near the end, regardless of the amount of winding of the magnetic tape 3 or the diameter of the reel hub. In the above embodiment, the arithmetic circuit 16 is

[Formula] was calculated, but it is not limited to this. For example, in order to simplify the circuit, it is set as (1/n _S + 1/n _T ), and the magnetic tape 3 transport speed is made to be approximately constant. However, as shown in FIG. 6, the effects of the present invention are not lost. Further, in the above embodiment, the measuring circuit 21 measures the time τ after the fast winding operation, but the measurement circuit 21 is not limited to measuring the time, but may also be configured to measure an amount proportional to the time, such as counting pulses, etc. You can get the effect of Further, although the control circuit 18 is given a command to wind the magnetic tape at the magnetic tape transfer speed of _V2 after ατ, the same effect can be obtained by changing the value of the reference signal 17 after ατ. Effects of the Invention As explained above, according to the magnetic tape device of the present invention, the transport speed of the magnetic tape near the end of the fast winding operation can be reduced with a simple circuit, thereby eliminating problems such as the reel hub coming off at the end of the magnetic tape. does not occur. In addition, the magnetic tape transfer speed is reduced by ατ (0<α<1), which is derived from the time τ required for the rotational speeds of both reel stands to become the same, so that the amount of tape wound on the reel hub and This provides an extremely practical effect in that the tape transport speed of the magnetic tape can be accurately reduced near the end of fast winding regardless of the size of the reel hub diameter.

[Brief explanation of the drawing]

Figure 1 is a plan view of the main parts of a conventional magnetic tape device.
Fig. 2 is a magnetic tape transport speed diagram during fast winding operation of a conventional magnetic tape device, Fig. 3 is a configuration diagram of a magnetic tape device in an embodiment of the present invention, and Fig. 4 is an embodiment of the present invention. FIGS. 5 and 6 are magnetic tape transfer speed diagrams of a magnetic tape device in another embodiment of the present invention. 1... Supply reel stand, 2... Supply reel hub,
3...Magnetic tape, 6...Take-up reel stand, 7...
Take-up reel hub, 8... Supply motor, 9... Take-up motor, 10, 11... Drive circuit, 12, 13...
...Detection head, 14, 15...Rotation speed detection circuit, 16...Arithmetic circuit, 17...Reference signal, 18
... Control circuit, 20 ... Rotation speed comparison circuit, 21
...Measurement circuit.

Claims (1)

[Claims] 1. A pair of reel stands that respectively engage and rotate integrally with a pair of reel hubs on which the magnetic tape is wound, and at least one of the pair of reel stands is driven to rotate in a direction in which the magnetic tape is wound. a reel stand driving means, a pair of rotational speed detection means for detecting the rotational speeds of the pair of reel stands, respectively, a rotational speed comparison means for detecting that the rotational speeds of the pair of reel stands have become the same; a measuring means for measuring the time required for the rotational speeds of the pair of reel stands to become the same after the start of the winding operation or an amount τ proportional to the time; ατ after the pair of reel stands rotate at a constant first magnetic tape winding speed and the rotational speeds of the pair of reel stands become the same.
(0<α<1); and a control means for controlling the reel drive means so that the reel drive means is rotated at a second magnetic tape winding speed that is lower than the first magnetic tape winding speed. .