Electromagnetic interference shielding construction in a radio telephone

• US 5,271,056 A
• Filed: 03/06/1991
• Issued: 12/14/1993
• Est. Priority Date: 04/12/1990
• Status: Expired due to Term

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Pesola, Mikko, Saarnimo, Timo, Leman, Ari, Valimaa, Veli-Matti
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Cumming, William D.
• Application Number:
  US07/666,882
• Time in Patent Office: 1,014 Days
• Field of Search: 379/58, 455/348, 379/428, 455/90, 455/117, 455/128
• US Class Current: 455/575.1
• CPC Class Codes: H04B 1/3833 Hand-held transceivers
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10

Abstract

A frame construction for a radio telephone or the operating device of a radio telephone. The radio telephone comprises a frame on which printed circuit boards containing telephone electronics are secured on both sides of a substantially flat, electrically conductive frame plate. The frame plate together with ground foils of the printed circuit boards form EMI-shielding for the components located on the sides of the printed circuit boards which face the frame plate. The frame plate preferably has a raised edge to which a printed circuit board is secured. Radio telephone housing parts are located on the two sides of the frame plate to form the radio telephone housing.

Claims

1. A radio telephone containing telephone electronic circuitry and components, comprising:

an electrically conductive frame including a frame plate with a continuous raised edge surrounding its outer periphery, said frame plate having a first face and an opposed second face;

a first printed circuit board having a first side substantially covered with a complete ground surface and a second opposed side having at least a first portion of said telephone electronic circuitry and components thereon;

said first circuit board being mounted to said raised edge with said first face of said frame plate opposing said first portion of telephone electronic circuitry and components on said second face of said first circuit board, said ground surface of said first board extending to said raised edge and being electrically joined to said frame to form with said frame an electromagnetic interference shielding for said first portion of telephone electronic circuitry and components on said second side of said first circuit board.

2. A radio telephone as in claim 1, further comprising a second printed circuit board having a first side substantially covered with a ground surface and second opposed side having a second portion of said telephone electronic circuitry and components thereon, said second circuit board being mounted to said frame with said second face of said frame plate opposing said second portion of telephone electronics and components on said second side of said second circuit board, said ground surface of said second circuit board being electrically joined to said frame to form with said frame an electromagnetic interference shielding for said second portion of said electronic circuitry and components on said second surface of said second circuit board.

3. A radio telephone as in claim 2, wherein said first portion on said first printed circuit board includes RF circuitry and RF components of said radio telephone, and said second printed circuit board includes logic and audio circuitry and components of said radio telephone, said circuitry and components on said first board being electromagnetic interference shielded from said circuitry and components on said second circuit board.

4. A radio telephone as in claim 2, further comprising circuit components mounted on said first side of at least one of said printed circuit boards, said circuit components on said at least one first side including a display, keyboard and speaker.

5. A radio telephone as in claim 3, further comprising circuit components mounted on the first side of at least one of said printed circuit boards, said circuit components on said at least one first side including a display, keyboard and speaker.

6. A radio telephone as in claim 1, further comprising housing parts, said housing parts being connected to said frame to define a radio telephone housing enclosing said first printed circuit board.

7. A radio telephone as in claim 2, further comprising housing parts, said housing parts being connected to said frame to define a radio telephone housing enclosing said first and said second printed circuit boards.

8. A radio telephone as in claim 6, wherein said housing encloses said frame.

9. A radio telephone as in claim 7, wherein said housing encloses said frame.

10. A radio telephone or the operating device of a radio telephone as in claim 2, wherein said frame plate has a continuous raised edge on at least said first face, said first circuit board being secured to said raised edge to provide an electromagnetic interference shielded space, which is defined between said frame plate, said raised edge, and the ground surface of said first circuit board.

11. A radio telephone as in claim 1, further comprising electrically conductive screws, said screws contacting said ground surface and connecting said first circuit board to said frame.

12. A radio telephone as in claim 1, wherein said ground surface is a conductive foil.

13. A radio telephone as in claim 2, wherein said ground surface is a conductive foil.

14. A radio telephone as in claim 10, wherein said ground surface is a conductive foil.

15. A radio telephone as in claim 1, wherein said frame plate is substantially flat.

16. A radio telephone as in claim 2, wherein said frame plate is substantially flat.