Electromagnetic interference (EMI) shield for a disk drive

An apparatus and method for shielding electromagnetic interference (EMI) for a disk drive includes a body portion for operatively securing to the disk drive. The body portion includes a flange portion. The flange portion includes a plurality of tab portions that substantially surround a perimeter portion of the body portion to allow a force applied to the body portion to deflect the plurality of tab portions and bias the plurality of tab portions against a contact surface to form a positive contact between the plurality of tab portions and the contact surface thereby shielding EMI.

FIELD OF THE INVENTION
 This invention relates generally to the field of electromagnetic
 interference (EMI) shields and, in particular, to an EMI shield for a disk
 drive.
 BACKGROUND OF THE INVENTION
 Electronic chassis that house electronic components for high-speed
 telecommunications and networking applications typically include a
 plurality of circuit board assemblies. Each circuit board assembly
 includes a circuit board that is attached to a channel-shaped mounting
 bracket.
 In certain applications, a disk drive (such as, for example, a floppy disk
 drive or a CD ROM disk drive) is mounted onto the circuit board of a
 circuit board assembly. The disk drive is positioned on the circuit board
 so that its receiving end is aligned with an opening formed in the
 mounting bracket. This arrangement allows an operator to access the
 receiving end of the disk drive to allow the insertion and ejection of a
 disk. However, there are several disadvantages to this arrangement.
 In particular, in many instances gaps are created between the disk drive
 and the opening in the mounting bracket due to parts which are out of
 tolerance. As a result, excessive amounts of electromagnetic radiation
 generated by the internal electronic components within the electronic
 chassis may leak out of the chassis through the gaps formed between the
 disk drive and the mounting bracket. Excessive electromagnetic
 interference (EMI) is a widespread problem in many electronic chassis
 applications, especially in the high-speed network systems products. These
 electronic chassis must meet very stringent regulatory emissions standards
 in the United States and in other foreign countries.
 Attempts have been made to provide shielding devices to reduce EMI
 emissions that exit through gaps between the disk drive and the mounting
 bracket. For example, Beryllium copper gaskets and metallic coated fiber
 gaskets have been used in an attempt to reduce EMI emissions. However,
 there are many disadvantages with these solutions, including the high
 costs associated with these materials. In addition, these conventional
 gasket designs are typically difficult to fabricate which results in
 increased manufacturing costs. Moreover, these gaskets typically do not
 provide a consistent positive and continuous contact between the disk
 drive and the mounting bracket. As a result, conventional solutions
 typically do not provide effective EMI shielding.
 Accordingly, it would be desirable to have an EMI shield that overcomes the
 disadvantages described above, and to provide a simple and cost effective
 EMI shield for a disk drive.
 SUMMARY OF THE INVENTION
 One aspect of the invention provides an electromagnetic interference (EMI)
 shield for a disk drive including a body portion for operatively securing
 to the disk drive. The body portion includes a flange portion having a
 plurality of tab portions. The plurality of tab portions substantially
 surrounds a perimeter portion of the body portion to allow a force applied
 to the body portion to deflect the plurality of tab portions and bias the
 plurality of tab portions against a contact surface to form a positive
 contact between the plurality of tab portions and the contact surface
 thereby shielding EMI. The plurality of tab portions may preferably be
 angled with respect to the contact surface to allow the plurality of tab
 portions to deflect when the force is applied to the body portion to form
 the positive contact between the plurality of tab portions and the contact
 surface. Each of the plurality of tab portions may preferably be angled at
 least about three degrees from the contact surface. The body portion may
 preferably have a rectangular-shape including a top wall, a bottom wall, a
 first side wall and a second side wall. The body portion may preferably be
 formed from a single piece of conductive material such as, for example,
 tin-plated cold rolled steel. The first and second side walls may each
 preferably include an opening to allow the body portion to be operatively
 secured to the disk drive. The opening may preferably be a slot.
 Another aspect of the invention provides an electromagnetic interference
 (EMI) shield for a disk drive. A circuit board is operatively secured to a
 bracket and a disk drive is operatively secured to the circuit board. A
 body portion is operatively secured to the disk drive. The body portion
 includes a flange portion having a plurality of tab portions. The
 plurality of tab portions substantially surrounds a perimeter portion of
 the body portion to allow a force applied to the body portion in a
 direction toward the bracket to deflect the plurality of tab portions and
 bias the plurality of tab portions against a contact surface of the
 bracket to form a positive contact between the plurality of tab portions
 and the contact surface. Electromagnetic radiation is thereby prevented
 from exiting through an opening in the bracket. Each of the plurality of
 tab portions may preferably be angled with respect to the contact surface
 of the bracket to allow the plurality of tab portions to deflect when the
 force is applied to the body portion to form the positive contact between
 the plurality of tab portions and the contact surface of the bracket. Each
 of the plurality of flange portions may preferably be angled at least
 about three degrees from the contact surface of the bracket. The body
 portion may preferably have a rectangular-shape including a top wall, a
 bottom wall, a first side wall, and a second end wall.
 Another aspect of the invention provides a method of shielding
 electromagnetic interference (EMI) for a disk drive. A circuit board and a
 disk drive operatively secured to the circuit board are provided. A body
 portion is operatively secured to the disk drive. The body portion
 includes a flange portion having a plurality of tab portions. The
 plurality of tab portions substantially surrounds a perimeter portion of
 the body portion. A force is applied to the body portion and the plurality
 of tab portions is deflected. The plurality of tab portions is biased
 against a contact surface of a bracket. A positive contact is formed
 between the plurality of tab portions and the contact surface of the
 bracket. Electromagnetic radiation is prevented from exiting through an
 opening in the bracket. The force may preferably be applied to the body
 portion in a direction toward the bracket. The circuit board may
 preferably be operatively secured to the bracket.
 Another aspect of the invention provides an electromagnetic interference
 (EMI) shield for a disk drive including a body portion for operatively
 securing to the disk drive. The body portion includes a flange portion
 having a plurality of tab portions. The plurality of tab portions is
 positioned along a longitudinal side of the body portion to allow a force
 applied to the body portion to deflect the plurality of tab portions and
 bias the plurality of tab portions against a contact surface to form a
 positive contact between the plurality of tab portions and the contact
 surface thereby shielding EMI. The plurality of tab portions may
 preferably be angled with respect to the contact surface to allow the
 plurality of tab portions to deflect when the force is applied to the body
 portion to form the positive contact between the plurality of tab portions
 and the contact surface. Each of the plurality of tab portions may
 preferably be angled at least about three degrees from the contact
 surface. The body portion may preferably have a generally planar-shape
 including a first side wall and a second side wall. Each of the first and
 second side walls may preferably include an opening to allow the body
 portion to be operatively secured to the disk drive. The opening may
 preferably be a slot. The body portion may preferably be formed from a
 single piece of conductive material such as, for example, tin-plated cold
 rolled steel.
 The invention provides the foregoing and other features, and the advantages
 of the invention will become further apparent from the following detailed
 description of the presently preferred embodiments, read in conjunction
 with the accompanying drawings. The detailed description and drawings are
 merely illustrative of the invention and do not limit the scope of the
 invention, which is defined by the appended claims and equivalents
 thereof.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
 As shown in FIGS. 1-6, a preferred embodiment of an electromagnetic
 interference (EMI) shield 10 for a disk drive 12 (see FIGS. 7-11) includes
 a body portion 14. Referring to FIGS. 1-6, the body portion 14 of the EMI
 shield 10 includes a flange portion 16. The flange portion 16 includes a
 plurality of tab portions 18 that substantially surround a perimeter
 portion 20 of the body portion 14. The plurality of tab portions 18 may
 preferably be formed by a plurality of slits 19 that also substantially
 surround the perimeter portion 20 of the body portion 14. The plurality of
 flange portions 18 created by the plurality of slits 19 may preferably be
 rectangular in shape, although other shapes and configurations are
 contemplated. Similarly the body portion 14 may preferably have a
 rectangular-shape and may preferably include a top wall 22, a bottom wall
 24, a first side wall 26 and a second side wall 28. Alternatively, the
 body portion 14 may have other shapes and configurations depending upon
 the shape and configuration of the disk drive 12 (see FIGS. 7-11). The
 body portion 14 of the EMI shield 10 may preferably be formed from a
 single piece of conductive material such as, for example, tin-plated cold
 rolled steel. However, the use of other types of conductive materials for
 the body portion 14 is contemplated. The one-piece design of the EMI
 shield 10 simplifies the fabrication process thereby reducing
 manufacturing costs. Moreover, the relatively low cost of tin-plated cold
 rolled steel provides a cost effective and economical solution for
 eliminating unacceptable amounts of electromagnetic interference.
 Referring to FIGS. 7-11, the disk drive 12 is operatively secured to a
 circuit board 30. The disk drive 12 may preferably be secured to the
 circuit board 30 by any conventional means. As shown in FIGS. 7-8 and 10,
 for example, conventional mounting brackets 32, 33 may preferably be used
 to secure the disk drive 12 to the circuit board 30. The disk drive 12 may
 preferably be any conventional disk drive such as, for example, a floppy
 disk drive. The circuit board 30 may preferably be any conventional
 printed circuit board.
 Referring again to FIGS. 7-11, the circuit board 30 is operatively secured
 to a faceplate bracket 34. The circuit board 30 may preferably be secured
 to the bracket 34 by any conventional means such as, for example, screws
 or bolts. The disk drive 12 is positioned on the circuit board 30 so that
 the receiving end 36 of the disk drive 12 is aligned with an opening 38 in
 the bracket 34 when the circuit board 30 is attached to the bracket 34.
 The body portion 14 of the EMI shield 10 is operatively secured to the
 disk drive 12. In the embodiment shown, for example, the body portion 14
 is inserted over an end portion 40 of the disk drive 12. When assembled,
 the plurality of tab portions 18 is positioned around the opening 38 in
 the bracket 34.
 During assembly of the circuit board 30, the disk drive 12, the EMI shield
 10, and the bracket 34, a force is applied to the body portion 14 of the
 EMI shield 10. The force may preferably be applied to the body portion 14
 in a direction toward the bracket 34. This causes the plurality of tab
 portions 18 to come in contact with a contact surface 42 of the bracket
 34. The force applied to the body portion 14 also deflects the plurality
 of tab portions 18 and biases the plurality of tab portions 18 against the
 contact surface 42 of the bracket 34 to form a positive contact between
 the plurality of tab portions 18 and the contact surface 42. The advantage
 of this arrangement is that the EMI shield 10 provides a positive and
 continuous contact between the disk drive 12 and the contact surface 42 of
 the bracket 34 even if the various components are out of tolerance. The
 EMI shield 10 assists in preventing electromagnetic radiation from exiting
 through the opening 38 in the bracket 34 thereby reducing electromagnetic
 interference emissions to the level required by the Federal Communications
 Commission (FCC) and other regulations.
 Referring again to FIGS. 1-6, the plurality of tab portions 18 may
 preferably be angled with respect to the contact surface 42 of the bracket
 32. This allows the plurality of tab portions 18 to deflect when the force
 is applied to the body portion 14 of the EMI shield 10. This in turn
 results in a positive contact between the plurality of tab portions 18 and
 the contact surface 42 of the bracket 34. Each of the plurality of tab
 portions 18 may preferably be angled at least about three degrees from the
 contact surface 42 of the bracket 34. However, other angles may be used
 depending upon the particular application. In the embodiment shown, the
 contact surface 42 is the inside surface of the bracket 34.
 As shown in FIG. 1, the first and second side walls 26, 28 of the body
 portion 14 each include openings 44, 46, respectively, to allow the body
 portion 14 of the EMI shield 10 to be operatively secured to the disk
 drive 12. In the embodiment shown in FIGS. 7-11, for example, body portion
 14 is attached to the mounting brackets 32, 33 for the disk drive 12 with
 conventional screws or bolts. As shown in FIG. 1, the openings 44, 46 each
 may preferably be configured as a slot, although other configurations for
 the openings 44, 46 are contemplated.
 FIGS. 12-15 illustrate an alternative preferred embodiment of an
 electromagnetic interference (EMI) shield 60 for the disk drive 12. The
 EMI shield 60 includes a body portion 62 for operatively securing to the
 disk drive 12 (see FIGS. 16-20). In the embodiment shown in FIGS. 12-13,
 the body portion 62 has a generally planar-shape including a first side
 wall 64 and a second side wall 66. The first and second side walls 64, 66
 each include openings 68, 70, respectively, to allow the body portion 62
 to be operatively secured to the disk drive 12. The openings 68, 70 may
 each be configured as a slot. The body portion 62 may preferably be formed
 from a single piece of conductive material, such as, for example,
 tin-plated cold rolled steel. However, other conductive materials for the
 body portion 62 are contemplated.
 Referring to FIGS. 12-15, the body portion 62 includes a flange portion 72
 having a plurality of tab portions 74. The plurality of tab portions 74
 are positioned along a longitudinal side 76 (see FIG. 12) of the body
 portion 62 to allow a force applied to the body portion 62 to deflect the
 plurality of tab portions 74. The plurality of tab portions 74 are biased
 against the contact surface 42 of the bracket 34 to form a positive
 contact between the plurality of tab portions 74 and the contact surface
 42 thereby shielding EMI. In particular, electromagnetic radiation is
 prevented from exiting through the opening 38 in the bracket 42.
 The plurality of tab portions 74 may preferably be angled with respect to
 the contact surface 42 to allow the plurality of tab portions 74 to
 deflect when the force is applied to the body portion 62. This in turn
 forms a positive contact between the plurality of tab portions 74 and the
 contact surface 42 of the bracket 34. Each of the plurality of tab
 portions 74 may preferably be angled at least about three degrees from the
 contact surface 42 of the bracket 34.
 As shown in FIGS. 16-20, a conductive fiber strip 80 may preferably be
 positioned on a top surface 82 of the disk drive 12 adjacent to and
 contacting the contact surface 42 of the bracket 34. This further prevents
 electromagnetic radiation from exiting through the opening 38 in the
 bracket 34.
 While the embodiments of the invention disclosed herein are presently
 considered to be preferred, various changes and modifications can be made
 without departing from the spirit and scope of the invention. The scope of
 the invention is indicated in the appended claims, and all changes that
 come within the meaning and range of equivalents are intended to be
 embraced therein.