FR2465291A1 - IMPROVEMENT RELATING TO TAPE DRIVE MECHANISMS FOR MAGNETIC TAPE RECORDERS AND READERS, IN PARTICULAR OF THE CASSETTE TYPE - Google Patents

Abstract

THIS MECHANISM FOR DRIVING THE MAGNETIC BAND INTO RECORDERS AND TAPE READERS, INCLUDES A BODY WHICH DETECTS THE FEED SPEED OF THE BAND20 AND IS AGENCY IN A MANNER TO CONTROL, THROUGH A FEEDBACK CIRCUIT, A ELECTRIC MOTOR9 WHICH IS MECHANICALLY COUPLED TO THE RECEIVER OR TAPE WINDING COIL4. THE DETECTION OF THE ADVANCE SPEED OF THE BAND IS CARRIED OUT BY MEASURING THE ANGULAR SPEED OF A CAPSTAN12 WHICH IS ASSOCIATED WITH DETECTORS13 OF ITS ANGULAR SPEED WHICH COMMAND A REACTION CIRCUIT WHICH ACTING ON THE ASSOCIATED MOTOR TO THE RECEIVER COIL, VARI THE SPEED OF THE latter TO MAINTAIN CONSTANT THE LINEAR SPEED OF THE MAGNETIC BAND.

Description

The present invention relates to related improvements.

  tifs to tape drive mechanics --- for-of -

  magnetic tape recorders and players, in particular

of the cassette type.

More specifically, the present invention relates to a belt drive mechanism for devices of the type defined above, a mechanism in which the belt drive is effected by direct application of a driving force to the hubs coils, and not by the classic system of

capstan and pressure roller.

Thanks to the system according to the present invention, it is possible to eliminate a large number of kinematic movements necessary for the correct drive of the strip and for the control of the hub of the take-up or take-up reel. so

  as the mechanisms necessary for the rapid advance of the web.

  According to the present invention, there is provided a belt drive system which comprises a member detecting the speed of advance of the belt and arranged so as to control,

by means of a reaction circuit, a motor coupled

  mechanically folded to the take-up or take-up reel, the arrangement being such that following the presetting of a reference value, a differentiating circuit detects the offset of the speed of advance of the strip with respect to that which is planned, controlling the engine speed which

is mechanically coupled to the take-up reel.

  The invention will now be described by means of its preferred embodiments, given by way of nonlimiting indication and with reference to the figures of the appended drawings, in which:

Fig. 1 generally represents the mechanism of

strip dragging according to the present invention.

  Fig. 2 schematically illustrates a first mode of

realization of the belt advance speed detection system.

  Fig. 3 represents an organ associated with the illustrated system

by fig. 2.

  Fig. 4 illustrates a modification of a detail of the

fig. 2.

  Fig. 5 illustrates another modification of a detail of

fig. 2.

  Fig. 6 is an electrical block diagram of the system

according to the invention.

Fig. 1 shows the layout - general mechanics of the

system according to the invention. A tape cassette set

  tick, designated by 1, is held in place by means not shown on a plate 2. The magnetic tape cassette 1 contains two windings of magnetic tape or coils 3, 4

  centered on hubs 5, 6. Assuming that the strip 20 moves

in the direction indicated by the arrows, the hub 6 is caused to rotate the winding reel 4 by means of a pulley 7 associated with a belt 8 and a motor 9. In

  its path between idler rollers 10, 11, the magnetic strip

  that is seized between a capstan 12 mounted mad and a roller

presser 13.

  According to the invention, the arrangement is such that the

  capstan 12, driven in rotation by the movement of transla-

tape, produces a signal proportional to its speed

  angular and, consequently, controls the motor 9 in one circuit

  closed-loop reaction cooked so that the drive speed is constant and corresponds to

the one that is planned.

The gig. 2, 3, 4 and 5 illustrate several solutions, given by way of example, for detecting the angular speed of the capstan 12, in direct relation to the speed of advance of the strip which is grasped between this capstan 12 and the pressure roller 13, kept in contact by elastic means

who were not represented.

  The capstan 12 is mounted idly in a bushing 14 and it is integral with a disc 15 with low inertia which is provided, as shown in FIG. 3, light and dark sectors alternating regularly along its periphery. An opto-electronic detector 16 of the transmission type reads the light and dark j marks arranged on the periphery of the disc 15 and produces a train of pulses which is in direct relation with

the tape speed.

It goes without saying that the device could take the form shown in FIG. 4, in which there is provided an optoelectronic detector 17 of the reflection type, or that of FIG. 5, in which the capstan 12 is integral with a toothed wheel 18 made of a ferromagnetic material, cooperating with an electromagnetic detector 19 of a known type which produces a train of pulses in correlation with the speed of passage

  teeth of the wheel 18 near the sensitive member.

  In fig. 6 is a simplified block diagram of the system according to the invention. By the mechanical transmissions ml, m2, the motor M drives the take-up reel hub l, and the angular speed detector of the capstan D which produces

an electrical signal. It goes without saying that the mechanical transmission

that ml is carried out by the magnetic strip during its movement

through the system.

  After possible processing in a reaction circuit F of known type, the signal produced by the detector D is applied to a comparator OP, in which it is compared with a reference signal produced by a reference source R. The signal error drives an amplifier A which controls the electric motor 1. It goes without saying that if the motor M is a DC motor, the amplifier A will be a simple amplifier. In the case where the motor is an alternating current motor whose speed of rotation is controlled by the frequency of the electric supply current, the block A would contain means for producing an energy of com:.: Ande à

  variable frequency depending on the error signal.

Although it has been shown in fig. 1 a motor 9 which is mechanically coupled to the single hub 6, it is obvious that it is possible, for example, to design a similar device for the hub 5 also, so as to implement the functions of reversing or rewinding the

  tape, but all of this is under the current skill of the specialist

list on the subject.

  The invention has been described by means of its embodiments.

currently preferred but as will be understood

  variations and modifications can easily be made

  in practice, without departing from the

  industrial property protection framework.

Claims (4)

  1. Drive mechanism of the recording tape   magnetic tape readers and readers, in particular of the cassette type, characterized in that it comprises a member which detects the speed of advance of the tape, arranged so as to control, by means of a feedback circuit , a   electrical notator mechanically coupled to the receiving coil   this or tape rewinder, the arrangement being such that, following the re-setting of a reference speed, a dif :: 'erenciator circuit detects the offset of the speed of advance of the tape relative to that which is provided, controlling accordingly the rotational speed of the motor which is coupled   mechanically to the take-up reel.   2. Miechanism according to claim 1, characterized in that the member detecting the speed of advance of the strip comprises a capstan mounted idly which is engaged with the strip and with which is associated an organ. Which detects its angular speed, so as to produce a signal proportional to the speed of advance linear of the strip. 20. Mechanism according to claim 2, characterized in that it is associated with the capstan an organ which is connected to an opto-electronic detector.   4. Iiécmcisme according to claim 2, characterized in that it is associated with the capstan a ferromagnetic element which   is connected to an electromagnetic detector.