GB1587423A

GB1587423A - Recording and/or playback apparatus

Info

Publication number: GB1587423A
Application number: GB2764977A
Authority: GB
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1976-07-05
Filing date: 1977-07-01
Publication date: 1981-04-01
Also published as: ATA490076A; FR2357975B3; FR2357975A1; DE2728696A1; JPS536005A; AT345577B

Description

(54) RECORDING AND/OR PLAYBACK APPARATUS (71) We, N.V. PHILIPS GLOEILAMPEN FABRIEKEN, a limited liability Company, organised and established under the laws of the Kingdom of the Netherlands, of Emmasingel 29, Eindhoven, the Netherlands, 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 recording and/ or playback apparatus having a rotary guide or drive member for a magnetic record carrier, or having a rotary member supporting a magnetic transducing head, which member comprises a shaft driven directly by an electric motor, the shaft passing through the motor and extending beyond it on opposite sides thereof and being concentric ally and rigidly connected to the rotor of the motor, a first pair of bearings being provided between the shaft and the stator of the motor, and a second pair of bearings being provided between the shaft and a stationary part of the apparatus other than the stator, the two bearings of the second pair being disposed on opposite sides of the stator.

In such apparatus the shaft may carry a record carrier in the form of a magnetic data-storage drum. Alternatively a drum half carrying magnetic heads made be mounted on the shaft, which half, together with a stationary second drum half, guides a record carrier in the form of a magnetic tape. The shaft may alternatively carry a disc which carries magnetic heads and 'which rotates between two stationary drum halves which again guide a record carrier in the form of a magnetic tape. Finally, the shaft may serve for directly driving a record carrier in the form of a magnetic tape. In all these cases a particularly accurate true rotation of the shaft is required, for which it is necessary that the shaft is correctly journalled by the bearings. There should therefore be no over-rigidity of the bearing arrangement of the shaft and the motor as a constructional unit.

According to the invention there is provided a recording and/ or playback apparatus having a rotory guide or drive member for a magnetic record carrier, or having a rotary member supporting a magnetic transducing head, which member comprises a shaft driven directly by an electric motor, the shaft passing through the motor and extending beyond it on opposite sides thereof and being concentrically and rigidly connected to the rotor of the motor, a first pair of bearings being provided between the shaft and the stator of the motor, and a second pair of bearings being provided between the shaft and a stationary part of the apparatus other than the stator, the two bearings of the second pair being disposed on opposite sides of the stator, wherein the stator is connected to said stationary part by a connecting device which is disposed substantially in a plane which extends perpendicularly to the shaft midway between the bearings of the second pair, said connecting device being arranged to inhibit rotation of the stator with the rotor but to permit the stator to adapt its position to that of the shaft relative to said stationary part in directions extending transversely of the axis of the shaft.

In one embodiment of the invention the connecting device comprises a stop on the stator, a stop on said stationary part' of the apparatus and a spring which urges the two stops against each other. The spring may be connected directly to the stop of the stator.

An embodiment of the invention will be described in more detail with reference to the drawings, in which Fig. 1 is a cross-section, taken on the line I-I in Fig. 2, of a tape-guide drum comprising' a stationary half and a half shaft which carries magnetic heads and is' 'mounted on a shaft driven directly by an electric motor and Fig. 2 is a cross-section taken on the line II--II in Fig. 1.

In Fig. 1 the reference numeral 1 designates the deck plate of a recording and/or playback apparatus, which is adapted for recording or playing back video information on a record carrier in the form of a magnetic tape. As is common practice in such equip ment the record carrier is fed around the surface of a drum in a helical path, rotary magnetic heads then entering into operative contact with the record carrier and scanning said record carrier along tracks which extend obliquely relative to its longitudinal direction. In the present embodiment such a drum 2 consists of a stationary first drum half 3 which is mounted on the deck plate 1 and a rotatable coaxial second drum half 4 on which magnetic heads 5 and 6 are mounted.

For a correct operation of the apparatus it is essential that the rotation of the rotary drum half 4 is absolutely true. The rotatable drum half 4 is mounted on the free upper end of a vertical shaft 7 and is clamped thereon by means of a clamp 8. The shaft 7, and thus the drum half 4, is driven directly by an electric motor 9, the rotor 10 of the motor being concentrically and rigidly connected to the shaft 7. The motor 9 and the shaft 7 constitute a constructional unit in which bearings 12 and 13 are mounted between the shaft 7 and the stator 11 of the motor. The stator 11 of the motor, which at the same time forms the motor housing, comprises a part 14, shown schematically, which in the usual manner cooperates with the rotor 10 to produce the driving force. In the present embodiment the shaft 7 passes right through the motor 9 so that parts of it extend on both sides of the motor.

To define the position of the rotatable drum half 4 relative to the stationary drum half 3 transversely of the axis of the drum 2, a pair of bearings is provided between the shaft 7 and the stationary part of the apparatus, which part consists of the drum half 3 and the deck plate 1. These bearings include a bearing 15 being mounted in an intermediate wall 16 of the drum half 3 and a second bearing 17 in the deck plate 1. A thrust bearing 18 which is connected to the deck plate 1 and on which the shaft 7 is seated at its lower end, defines the distance between the two drum halves 3 and 4 in the axial direction. As can be seen from Fig. 1, the two bearings 15 and 17 are disposed on opposite sides of the stator 11, the arrangement being such that the stator, which exhibits some play relative to the shaft and the rotor 10 in the direction of the axis of the shaft 7, freely bears on the deck plate 1 under the influence of its own weight.

The stator 11 is connected to the stationary part 1, 3 of the apparatus by a connecting device 19 which inhibits rotation of the stator with the rotor. In the present example the connecting device 19 is constituted by an outwardly radially projecting stop 20 on the stator 11, an inwardly radially projecting stop 21 on the stationary drum half 3, and a tension spring 22 which urges the two stops 20 and 21 against each other The spring is connected directly to the stop 20 and drum half 3 and passes through a bore 23 formed in the stop 21. As can be seen in Fig. 1 the stops 20 and 21 are arranged so that they are disposed substantially in a plane which extends perpendicularly to the shaft midway between the bearings 15 and 17. This ensures that the connecting device 19 does not give rise to unequal loading of the bearings 15 and 17, which is important in respect of accurate running of the shaft 7.

The stop 20 can move relative to the stop 21 in directions extending transversely of the axis of the shaft 7 sufficiently to permit the stator 11 to adapt its position to that of the shaft 7 in such directions relative to the stationary part of the apparatus, namely, the part consisting of the deck plate 1 and the stationary drum half 3. This ensures that no over-rigidity in the bearing arrangement of the constructional unit consisting of the shaft and motor can occur.

WHAT WE CLAIM IS: 1. A recording and/or playback apparatus having a rotor guide or drive member for a magnetic record carrier, or having a rotary member supporting a magnetic transducing head, which member comprises a shaft driven directly by an electric motor, the shaft passing through the motor and extending beyond it on opposite sides thereof and being concentrically and rigidly connected to the rotor of the motor, a first pair of bearings being provided between the shaft and the stator of the motor, and a second pair of bearings being provided between the shaft and a stationary part of the apparatus other than the stator, the two bearings of the second pair being disposed on opposite sides of the stator, wherein the stator is connected to said stationary part by a connecting device which is disposed substantially in a plane which extends perpendicularly to the shaft midway between the bearings of the second pair, and connecting device being arranged to inhibit rotation of the stator with the rotor but to permit the stator to adapt its position to that of the shaft relative to said stationary part in directions extending transversely of the axis of the shaft.

2. An apparatus as claimed in Claim 1, wherein the connecting device comprises a stop on the stator, a stop on said stationary part of the apparatus, and a spring which urges the two stops against each other.

3. An apparatus as claimed in Claim 2,

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ment the record carrier is fed around the surface of a drum in a helical path, rotary magnetic heads then entering into operative contact with the record carrier and scanning said record carrier along tracks which extend obliquely relative to its longitudinal direction. In the present embodiment such a drum 2 consists of a stationary first drum half 3 which is mounted on the deck plate 1 and a rotatable coaxial second drum half 4 on which magnetic heads 5 and 6 are mounted. For a correct operation of the apparatus it is essential that the rotation of the rotary drum half 4 is absolutely true. The rotatable drum half 4 is mounted on the free upper end of a vertical shaft 7 and is clamped thereon by means of a clamp 8. The shaft 7, and thus the drum half 4, is driven directly by an electric motor 9, the rotor 10 of the motor being concentrically and rigidly connected to the shaft 7. The motor 9 and the shaft 7 constitute a constructional unit in which bearings 12 and 13 are mounted between the shaft 7 and the stator 11 of the motor. The stator 11 of the motor, which at the same time forms the motor housing, comprises a part 14, shown schematically, which in the usual manner cooperates with the rotor 10 to produce the driving force. In the present embodiment the shaft 7 passes right through the motor 9 so that parts of it extend on both sides of the motor. To define the position of the rotatable drum half 4 relative to the stationary drum half 3 transversely of the axis of the drum 2, a pair of bearings is provided between the shaft 7 and the stationary part of the apparatus, which part consists of the drum half 3 and the deck plate 1. These bearings include a bearing 15 being mounted in an intermediate wall 16 of the drum half 3 and a second bearing 17 in the deck plate 1. A thrust bearing 18 which is connected to the deck plate 1 and on which the shaft 7 is seated at its lower end, defines the distance between the two drum halves 3 and 4 in the axial direction. As can be seen from Fig. 1, the two bearings 15 and 17 are disposed on opposite sides of the stator 11, the arrangement being such that the stator, which exhibits some play relative to the shaft and the rotor 10 in the direction of the axis of the shaft 7, freely bears on the deck plate 1 under the influence of its own weight. The stator 11 is connected to the stationary part 1, 3 of the apparatus by a connecting device 19 which inhibits rotation of the stator with the rotor. In the present example the connecting device 19 is constituted by an outwardly radially projecting stop 20 on the stator 11, an inwardly radially projecting stop 21 on the stationary drum half 3, and a tension spring 22 which urges the two stops 20 and 21 against each other The spring is connected directly to the stop 20 and drum half 3 and passes through a bore 23 formed in the stop 21. As can be seen in Fig. 1 the stops 20 and 21 are arranged so that they are disposed substantially in a plane which extends perpendicularly to the shaft midway between the bearings 15 and 17. This ensures that the connecting device 19 does not give rise to unequal loading of the bearings 15 and 17, which is important in respect of accurate running of the shaft 7. The stop 20 can move relative to the stop 21 in directions extending transversely of the axis of the shaft 7 sufficiently to permit the stator 11 to adapt its position to that of the shaft 7 in such directions relative to the stationary part of the apparatus, namely, the part consisting of the deck plate 1 and the stationary drum half 3. This ensures that no over-rigidity in the bearing arrangement of the constructional unit consisting of the shaft and motor can occur. WHAT WE CLAIM IS:

1. A recording and/or playback apparatus having a rotor guide or drive member for a magnetic record carrier, or having a rotary member supporting a magnetic transducing head, which member comprises a shaft driven directly by an electric motor, the shaft passing through the motor and extending beyond it on opposite sides thereof and being concentrically and rigidly connected to the rotor of the motor, a first pair of bearings being provided between the shaft and the stator of the motor, and a second pair of bearings being provided between the shaft and a stationary part of the apparatus other than the stator, the two bearings of the second pair being disposed on opposite sides of the stator, wherein the stator is connected to said stationary part by a connecting device which is disposed substantially in a plane which extends perpendicularly to the shaft midway between the bearings of the second pair, and connecting device being arranged to inhibit rotation of the stator with the rotor but to permit the stator to adapt its position to that of the shaft relative to said stationary part in directions extending transversely of the axis of the shaft.

3. An apparatus as claimed in Claim 2,

wherein the spring is connected directly to the stop of the stator.

4. A recording and/or playback apparatus substantially as herein described with reference to the accompanying drawings.