Compact motor mount for information storage devices

Abstract

A compact motor mount for cassette drive systems includes a base plate in the form of a laminate that includes at least one planar layer of ferromagnetic material sandwiched between two printed circuit boards. A capstan motor is supported by the base plate. The stator coil assembly of the capstan motor is mounted on one side of the base plate directly on one of the two printed circuit boards. At least one winding drive motor also is supported in common with the capstan motor by the base plate. The stator coil assembly of the drive motor is mounted on the other side of the base plate directly on the second of the two printed circuit boards. Each of the motors has a permanent magnet rotor mounted on a shaft and facing the respective stator coil assemblies across an air gap defined therebetween.

We claim: 
     
       1. A drive system for cassettes comprising: a base plate in the form of a laminate that includes at least one planar layer of ferromagnetic material sandwiched between two printed circuit boards;   a capstan motor supported by the base plate, the motor including a stator coil assembly mounted directly on the outer planar surface of a first of the two printed circuit boards, a shaft supported by the base plate and mounted so as to extend generally at right angles to the base plate, and a permanent magnet rotor mounted on the shaft and facing the stator coil assembly across an air gap defined therebetween; and   at least one winding drive motor supported in common with the capstan motor by the base plate, the motor including a stator coil assembly mounted directly on the outer planer surface of the second of the two printed circuit boards, a shaft supported by the base plate and mounted so as to extend generally at right angles to the base plate at a preset distance from and parallel to the shaft of the capstan motor, and permanent magnet rotor mounted on the shaft and facing the drive stator coil assembly across an air gap defined therebetween.   
     
     
       2. A drive system in accordance with claim 1, wherein the base plate is mounted on a separate chassis housing which supplies rigidity to the total assembly. 
     
     
       3. A drive system in accordance with claim 1, wherein the layer of ferromagnetic material is sufficiently thick to provide rigidity to the base plate and drive system. 
     
     
       4. A drive system in accordance with claim 1, wherein the laminate includes two layers of ferromagnetic material on either side of a planar core of solid material, all sandwiched between the two printed circuit boards. 
     
     
       5. A drive system in accordance with one of claims 1 to 4, wherein the ferromagnetic material is soft iron. 
     
     
       6. A drive system in accordance with one of claims 1 to 4, wherein the capstan and the at least one winding drive motors are flat air gap motors. 
     
     
       7. A drive system in accordance with one of claims 1 to 4, wherein the capstan and the at least one winding drive motors are three phase motors. 
     
     
       8. A drive system in accordance with claim 6, wherein the motors are three phase and the stators include six equidistantly spaced coils forming a planar circle around the shaft as center. 
     
     
       9. A drive system in accordance with one of claims 1 to 4, wherein the rotors of the capstan and the at least one drive motors each have a diameter which in relation to the preset distance between shafts cause the rotors to radially overlap one another in their axially spaced apart relation. 
     
     
       10. A drive system in accordance with one of claims 1 to 4, wherein each of the printed circuit boards includes electrical circuit connections of the stator coils and in addition active circuit elements for the operation of the respective motors. 
     
     
       11. A drive system in accordance with one of claims 1 to 4, wherein the motors are external rotor motors. 
     
     
       12. A drive system in accordance with one of claims 1 to 4, wherein the motors are brushless dc motors. 
     
     
       13. A drive system in accordance with one of claims 1 to 4, wherein at least one of the printed circuit boards includes a meander winding located to be magnetically acted upon by the associated permanent magnet rotor. 
     
     
       14. A drive system in accordance with claim 2, wherein bearing support tubes are formed integrally with the chassis housing, the bearing support tubes containing bearing means rotatingly mounting the respective shafts, including the capstan shaft. 
     
     
       15. A drive system in accordance with claim 3, wherein clearance holes are provided in the base plate laminate for the shafts and associated bearing support tubes to extend therethrough and a plurality of screw holes are provided in the base plate around the clearance holes to receive screws for mounting the bearing support tubes. 
     
     
       16. A drive system in accordance with one of claims 1 to 4, wherein in respect of the capstan motor, the end of the shaft around which are the capstan heads is on the opposite side of the base plate from the corresponding stator and rotor, the heads thereby being magnetically shielded by the ferromagnetic material of the base plate laminate. .Iadd.17. A drive for an information storage device having a moveable storage medium and a head associated therewith to permit information to be stored on and retrieved from the storage medium, said drive comprising: a base plate including a planar layer of ferromagnetic material having a printed circuit board affixed to one side thereof; and   a motor supported by said base plate, said motor including a stator coil assembly mounted on the outer surface of said printed circuit board and a shaft rotatably mounted on said base plate, said shaft having a first end portion extending from said printed circuit board generally at a right angle thereto adjacent the stator coil assembly and a second end portion extending from said ferromagnetic layer generally at a right angle thereto for operative engagement with the information storage device to allow the head to store information on and retrieve information from the storage medium, said motor further including a permanent magnet rotor attached to the first end portion of said shaft, said rotor providing a stray flux return path from said stator coil assembly to said base plate via a first air gap between said stator coil assembly and said rotor and a second air gap between said rotor and said base plate to provide at least some shielding of the storage medium from stray electromagnetic interference emitted from the stator coil assembly. .Iaddend..Iadd.18. A drive in accordance with claim 17, wherein the base plate is mounted on a separate chassis housing which supplies rigidity to the total assembly. .Iaddend..Iadd.19. A drive in accordance with claim 17, wherein the layer of ferromagnetic material is sufficiently thick to provide rigidity to the base plate and drive. .Iaddend..Iadd.20. A drive in accordance with claim 17 wherein the base plate comprises a laminate of two layers of ferromagnetic material on either side of a planar core of solid material wherein said printed circuit board is affixed to one of the two layers of ferromagnetic material. .Iaddend..Iadd.21. A drive in accordance with claim 17 wherein the ferromagnetic material is soft iron. .Iaddend..Iadd.22. A drive in accordance with claim 17 wherein the motor is a flat air gap motor. .Iaddend..Iadd.23. A drive in accordance with claim 17 wherein the motor is a three phase motor. .Iaddend..Iadd.24. A drive in accordance with claim 22, wherein the stators include six equidistantly spaced coils forming a planar circle around the shaft as center. .Iaddend..Iadd.25. A drive in accordance with claim 17 wherein said printed circuit board includes electrical circuit connections of the stator coils and active circuit elements for the operation of the motor. .Iaddend..Iadd.26. A drive in accordance with claim 17 wherein the motor is an external rotor motor. .Iaddend..Iadd.27. A drive in accordance with claim 17 wherein the motor is a brushless dc motor. .Iaddend..Iadd.28. A drive in accordance with claim 18 wherein said printed circuit board includes a meander winding located to be magnetically acted upon by the associated permanent magnet rotor. .Iaddend..Iadd.29. A drive in accordance with claim 20, wherein a bearing support tube is formed integrally with the chassis housing, said tube including means for   
     
     
        rotatably mounting said shaft thereto. .Iaddend..Iadd.30.  A drive in accordance with claim 20 wherein a clearance hole is provided in the base plate for the shaft and associated bearing support tube to extend therethrough and a plurality of screw holes are provided in the base plate around the clearance holes to receive strews for mounting the bearing support tube. .Iaddend..Iadd.31. A drive in accordance with claim 17 wherein said rotor is cup-shaped. .Iaddend..Iadd.32. A drive in accordance with claim 17 wherein said rotor is cylindrical and has a diameter greater than that of the stator coil assembly, said rotor having a rim extending towards said printed circuit board to form said second air gap. .Iaddend..Iadd.33. A drive for an information storage device having a moveable storage medium and a head associated therewith to permit information to be stored on and retrieved from the storage medium, said drive comprising: a base plate including a planar layer of ferromagnetic material having a printed circuit board affixed to one side thereof; and   a motor supported by said base plate, said motor including a stator coil assembly mounted on the outer surface of said printed circuit board and a shaft rotatably mounted on said base plate, said shaft having a first end portion extending from said printed circuit board generally at a right angle thereto adjacent the stator coil assembly and a second end portion extending from said ferromagnetic layer generally at a right angle thereto for operative engagement with the information storage device to allow the head to store information on and retrieve information from the storage medium, said motor further including a cup-shaped permanent magnet rotor attached to the first end portion of said shaft, said rotor having a rim disposed at its outer periphery which extends towards said base plate to substantially enclose said stator coil assembly within the space defined by said rotor and said base plate and provide at least some shielding of the storage medium from stray electromagnetic interference emitted from the stator coil assembly. .Iaddend..Iadd.34. A drive in accordance with claim 33, wherein the base plate is mounted on a separate chassis housing which supplies rigidity to the total assembly. .Iaddend..Iadd.35. A drive in accordance with claim 33, wherein the layer of ferromagnetic material is sufficiently thick to provide rigidity to the base plate and drive. .Iaddend..Iadd.36. A drive in accordance with claim 33, wherein the base plate comprises a laminate of two layers of ferromagnetic material on either side of a planar core of solid material wherein said printed circuit board is affixed to one of the two layers of ferromagnetic material. .Iaddend..Iadd.37. A drive in accordance with claim 33, wherein the ferromagnetic material is soft iron. .Iaddend..Iadd.38. A drive in accordance with claim 33, wherein the motor is a flat air gap motor. .Iaddend..Iadd.39. A drive in accordance with claim 33, wherein the motor is a three phase motor. .Iaddend..Iadd.40. A drive in accordance with claim 37, wherein the stators include six equidistantly spaced coils forming a planar circle around the shaft as center. .Iaddend..Iadd.41. A drive in accordance with claim 33, wherein said printed circuit board includes electrical circuit connections of the stator coils and active circuit elements for the operation of the motor. .Iaddend..Iadd.42. A drive in accordance with claim 33, wherein the motor is an external rotor motor. .Iaddend..Iadd.43. A drive in accordance with claim 33, wherein the motor is a brushless dc motor. .Iaddend..Iadd.44. A drive in accordance with claim 33, wherein said printed circuit board includes a meander winding located to be magnetically acted upon by the associated permanent magnet rotor. .Iaddend..Iadd.45. A drive in accordance with claim 34, wherein a bearing support tube is formed integrally with the chassis housing, said tube including means for rotatably mounting said shaft thereto. .Iaddend..Iadd.46. A drive in accordance with claim 35, wherein a clearance hole is provided in the base plate for the shaft and associated bearing support tube to extend therethrough and a plurality of screw holes are provided in the base plate around the clearance holes to receive screws for mounting the bearing support tube. .Iaddend..Iadd.47. A drive in accordance with claim 33, wherein said rotor is cylindrical and has a diameter greater than that of the stator coil assembly, said rotor having a rim extending towards said printed circuit board to form said second air gap. .Iaddend.