GB1576812A - Drive mechanism for a tape recorder - Google Patents

Description

(54) DRIVE MECHANISM FOR A TAPE RECORDER (71) We, MAGNETRONIC GESELLSCHAFT FUR ELEKTRONISCH-MECHANISCHE GERATE M.

B.H. & Co. ENTWICKLUNGS KG, a German Company, of Kreuzhofstrasse 10, D-8000 Munchen 71, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a drive mechanism for magnetic tape apparatus, in particular cassette tape recorders, with their own winding motors.

In a known driving mechanism, a motor is rigidly connected to the driving pinion, a single toothed intermediate wheel is provided which is in continuous engagement with the pinion, which is mounted for limited movement in its plane on a circular path around the motor shaft and in the two end positions meshes with a respective one of the gear wheels of the winding plates. In this case the intermediate wheel is preferably decelerated in such a manner that after reversal of the motor its construction permits it to be displaced initially in a substantially translatory manner as far as stand-still engagement with one of the gear wheels of the winding plates. The known construction has stood the test excellently.

According to this invention, there is provided a tape recorder having a capstan, two rotatable spindles, a drive motor for the capstan, and a drive mechanism with a further motor which can drive one of the spindles in one direction or the other spindle in the opposite direction, the mechanism comprising a wheel rotated about its axis by the further motor a control lever freely pivoted about an axis parallel to the axis of rotation of the wheel, two friction wheels mounted on the lever, one on each side of the pivot axis, with the friction at the friction wheel bearings being adjustable and greater than the bearing friction at the control lever pivot, and a belt running around the motor driven wheel and the two friction wheels, and driving the friction wheels, the outer peripheral surface of the belt contacting one or other of the spindles and driving the contacted spindle by virtue of the friction between the belt and the spindle.

Advantageously at least one slipping clutch for decelerating the friction wheels is provided between the control lever and the underside of a friction wheel.

Alternatively, at least one magnetic friction clutch may be interposed between friction wheel and control lever.

Advantageously the bearing pin of the control lever is disposed centrally above an imaginary line connecting the axes of the friction wheels.

In the older construction an intermediate wheel is required in addition to a rocker member. The rocker member must have two bearings, and precise adjustment and assembly, i.e. more accurate production, is necessary, since all the drive-transmitting wheels are gear wheels. In the invention, only frictiondriven wheels are required in addition to the control lever and the belt. The assembly is obviously extremely simple. Highly quiet running is attained as a consequence of the friction between rubber and rubber. Servicing is simple. Worn parts are simply and rapidly replaced. The construction is robust. The wheels may be produced from a synthetic resin with low production precision. The bearing is simple, since only one pivot point is present. The belt drive has a self-tensioning effect, i.e. it exhibits a servo effect. Due to the deceleration, a power amplification and as a consequence of the latter a self-wedging effect is produced. The squeezing pressure is increased proportional to the torque transmitted.

Preferably two slipping clutches are provided, one at each friction wheel. However, the invention still works with only one slipping clutch. It is only necessary that the friction of the slipping clutch be greater than the bearing pin friction. This is attained in that the friction of for example the felt employed as a slipping clutch is greater than the friction at the lever bearing pin.

Varied belt forms can be used, for example flat belts, including flat belts constructed on the inside as toothed belts, round belts, etc.

The friction of the slipping clutch may be adjusted, for example by spring pressure. The invention may be applied to horizontal operation as well as vertical operation.

Further features and advantages of the invention will be apparent from the following description of one example of a constructional form of the invention which is now to be discussed in detail with reference to the accompanying drawings, Figure 1 is a diagrammatic view from above of a driving mechanism operating in one direction; Figure 2 is a diagrammatic view from above of the mechanism operating in the opposite direction; and Figure 3 is a section on the line III--III in Figure 2.

In Figures 1 and 2 the driving motor is located under the driving wheel 14. By means of the belt 12 which may be, for example, a V-belt the wheel 14 drives the fur'cation wheels 10 which are rotatably mounted on a control lever 20. The control lever 20 itself is mounted on a bearing pin 22 by means of a bearing sleeve 24. In this case the bearing sleeve 24 is securely riveted to the control lever 20. The shaft of the bearing pin 22 is rigidly seated on a chassis of the machine.

Upon reversal of the driving motor the driving wheel starts rotating in the opposite direction. Since the friction in the bearings of the friction wheels 10 is greater than the bearing friction of the control lever, the lever 20 swings around the bearing pin 22, while the belt 12 drives the friction wheels 10 around their shafts 26. The arrangement therefore moves from the position shown in Figure 1, where the spindle or reel plate 16 is driven Bnti-clockwise, to the position shown in Figure 2, where the spindle or plate 18 is driven clockwise, by friction between the outer surface of belt 12 and the periphery of plate 18.

Figure 3 which is a section on the line III III in Figure 2 permits the construction of the device to be seen more clearly. It may be clearly seen how the bearing sleeve 24 is riveted to the control lever 20, and how the bearing shaft 22 is seated rigidly on the chassis 44. The bearing sleeve is secured on the shaft 22 by the locking ring 32. The left-hand friction wheel 10 is shown in section in the Figure. Its periphery has a V-groove for receiving a V-belt. It may be seen clearly how a friction-producing felt disc 40 is arranged underneath the hub 11 of the wheel 10. In this case the friction wheel 10 is loaded by a helical spring which is covered by a slide disc 36 in an adjustable manner and is secured on the stationary bearing shaft 26 by a locking ring. Obviously in place of the helical compression spring 38 any other spring may be employed, for example a plate spring. The connection between the stationary shaft 26 and the control lever 20 is ensured by a rivet bush 42.

In operation, when, for example, the one winding plate 16 has wound in the one direction and then the other winding plate 18 is to wind (rewind), it is merely necessary to reverse the electrical polarity of the motor.

The drive belt disc 14 drives then the belt 12 in the other direction. Since the bearing friction at the friction wheels is greater than the bearing friction of the control lever pivot pin 22, the control lever 20 is swung round and the connection between the friction wheel 10 previously in engagement and the winding plate 16 is cancelled. After the termination of the swinging process the other friction wheel 10 or the belt comes into contact with the other winding plate 18. Owing to the friction between the outside of the belt and the friction material of the respective winding plate, the other winding plate 18 is driven in the opposite direction from the previous winding plate 16. The pressure force is further amplified at higher powers.

A capstan (not shown) is provided with a separate drive motor (not shown).

Since no gear wheels are employed, the running quietness is very great. The belt drive readjusts itself in practice upon wear or assembly inaccuracies.

Thus only a single transmission element, namely the belt, which runs over the two friction wheels mounted on the control lever, is present between the driving belt disc and the winding plate.

Compared with the driving mechanisms commercially available, there exists the further advantage that separate coupling devices for the switching device etc. may be omitted. Any reversible motor is suitable, for example a direct current motor with collector, which has two running directions.

WHAT WE CLAIM IS: 1. A tape recorder having a capstan, two rotatable spindles, a drive motor for the capstan, and a drive mechanism with a further motor which can drive one of the spindles in one direction or the other spindle in the opposite direction, the mechanism comprising a wheel having an axis and arranged to be rotated about its axis by the further motor, a control lever freely pivoted about an axis parallel to the axis of rotation of the wheel, two friction wheels mounted on the lever, one on each side of the pivot axis, with the friction at the friction wheel bearings being adjustable and greater than the friction at the control lever pivot, and a belt running round the motor driven wheel and the two

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. as a slipping clutch is greater than the friction at the lever bearing pin. Varied belt forms can be used, for example flat belts, including flat belts constructed on the inside as toothed belts, round belts, etc. The friction of the slipping clutch may be adjusted, for example by spring pressure. The invention may be applied to horizontal operation as well as vertical operation. Further features and advantages of the invention will be apparent from the following description of one example of a constructional form of the invention which is now to be discussed in detail with reference to the accompanying drawings, Figure 1 is a diagrammatic view from above of a driving mechanism operating in one direction; Figure 2 is a diagrammatic view from above of the mechanism operating in the opposite direction; and Figure 3 is a section on the line III--III in Figure 2. In Figures 1 and 2 the driving motor is located under the driving wheel 14. By means of the belt 12 which may be, for example, a V-belt the wheel 14 drives the fur'cation wheels 10 which are rotatably mounted on a control lever 20. The control lever 20 itself is mounted on a bearing pin 22 by means of a bearing sleeve 24. In this case the bearing sleeve 24 is securely riveted to the control lever 20. The shaft of the bearing pin 22 is rigidly seated on a chassis of the machine. Upon reversal of the driving motor the driving wheel starts rotating in the opposite direction. Since the friction in the bearings of the friction wheels 10 is greater than the bearing friction of the control lever, the lever 20 swings around the bearing pin 22, while the belt 12 drives the friction wheels 10 around their shafts 26. The arrangement therefore moves from the position shown in Figure 1, where the spindle or reel plate 16 is driven Bnti-clockwise, to the position shown in Figure 2, where the spindle or plate 18 is driven clockwise, by friction between the outer surface of belt 12 and the periphery of plate 18. Figure 3 which is a section on the line III III in Figure 2 permits the construction of the device to be seen more clearly. It may be clearly seen how the bearing sleeve 24 is riveted to the control lever 20, and how the bearing shaft 22 is seated rigidly on the chassis 44. The bearing sleeve is secured on the shaft 22 by the locking ring 32. The left-hand friction wheel 10 is shown in section in the Figure. Its periphery has a V-groove for receiving a V-belt. It may be seen clearly how a friction-producing felt disc 40 is arranged underneath the hub 11 of the wheel 10. In this case the friction wheel 10 is loaded by a helical spring which is covered by a slide disc 36 in an adjustable manner and is secured on the stationary bearing shaft 26 by a locking ring. Obviously in place of the helical compression spring 38 any other spring may be employed, for example a plate spring. The connection between the stationary shaft 26 and the control lever 20 is ensured by a rivet bush 42. In operation, when, for example, the one winding plate 16 has wound in the one direction and then the other winding plate 18 is to wind (rewind), it is merely necessary to reverse the electrical polarity of the motor. The drive belt disc 14 drives then the belt 12 in the other direction. Since the bearing friction at the friction wheels is greater than the bearing friction of the control lever pivot pin 22, the control lever 20 is swung round and the connection between the friction wheel 10 previously in engagement and the winding plate 16 is cancelled. After the termination of the swinging process the other friction wheel 10 or the belt comes into contact with the other winding plate 18. Owing to the friction between the outside of the belt and the friction material of the respective winding plate, the other winding plate 18 is driven in the opposite direction from the previous winding plate 16. The pressure force is further amplified at higher powers. A capstan (not shown) is provided with a separate drive motor (not shown). Since no gear wheels are employed, the running quietness is very great. The belt drive readjusts itself in practice upon wear or assembly inaccuracies. Thus only a single transmission element, namely the belt, which runs over the two friction wheels mounted on the control lever, is present between the driving belt disc and the winding plate. Compared with the driving mechanisms commercially available, there exists the further advantage that separate coupling devices for the switching device etc. may be omitted. Any reversible motor is suitable, for example a direct current motor with collector, which has two running directions. WHAT WE CLAIM IS:

1. A tape recorder having a capstan, two rotatable spindles, a drive motor for the capstan, and a drive mechanism with a further motor which can drive one of the spindles in one direction or the other spindle in the opposite direction, the mechanism comprising a wheel having an axis and arranged to be rotated about its axis by the further motor, a control lever freely pivoted about an axis parallel to the axis of rotation of the wheel, two friction wheels mounted on the lever, one on each side of the pivot axis, with the friction at the friction wheel bearings being adjustable and greater than the friction at the control lever pivot, and a belt running round the motor driven wheel and the two

friction wheels to drive the friction wheels, the outer peripheral surface of the belt contacting the periphery of one or other of the spindles and driving the contacted spindle by virtue of friction between the belt and the spindle.

2. A tape recorder as claimed in claim 1, including a slipping clutch for increasing the friction between the control lever and one or both of the friction wheels.

3. A tape recorder as claimed in claim 1, in which a magnetic friction clutch is interposed between one or both of the friction wheels and the control lever.

4. A tape recorder as claimed in claim 1 or 2, in which the belt is toothed on the side contacting the friction wheels.

5. A tape recorder as claimed in any one of claims 1 to 4, in which the control lever is pivoted on a pin disposed centrally along an imaginary line connecting the axes of the friction wheels.

6. A tape recorder as claimed in claim 1, substantially as described with reference to the accompanying drawings.