Protective case for electrical instruments on circuit boards

• US 4,092,698 A
• Filed: 07/01/1977
• Issued: 05/30/1978
• Est. Priority Date: 09/16/1976
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Brefka, Paul E.
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US05/812,059
• Time in Patent Office: 333 Days
• Field of Search: 361/399, 361/346
• US Class Current: 361/752
• CPC Class Codes: G01R 1/04 Housings; Supporting members; Arrangements of terminals
• CPC Class Codes: G12B 9/00 Housing or supporting of instruments or other apparatus
• CPC Class Codes: H02B 1/048 Snap mounting
• CPC Class Codes: H05K 7/12 Resilient or clamping means for holding component to structure

Abstract

A protective case for an electrical instrument on a circuit board, arranged to mount the instrument upon a panel in an opening provided therein. The case is characterized by a housing having an end opening for introduction of the circuit board therein and a snap-in mounting structure for automatically and securely mounting a circuit board within the housing. The mounting structure includes means forming a ledge, provided for example by four corner platforms molded into the housing, for supporting one side of the circuit board. Two pairs of opposed resilient fingers, preferably molded integrally with the walls of the housing, extend with an inward cant along the path of the circuit board from opposite interior sides of the housing to be flexed outwardly by the edges of the circuit board as it is introduced into the housing. The resilient fingers terminate in front faces, preferably formed with beveled stepped surfaces, which are spaced from the ledges to allow the resilient fingers to flex inwardly to fit their front faces against the opposite side of the circuit board when it is positioned with its one side in contact with the ledge. The circuit board thus becomes securely mounted in the housing automatically upon its introduction therein, without resort to separate fastening means or tools. The case further has a back wall apertured to receive connector pins on the circuit board, a front cover, and resilient catches extending outwardly from other side walls of the housing for attachment of the housing to an instrument panel.

Claims

1. A protective case for a panel-mounted electrical instrument of the type having internal electrical circuitry on a circuit board, said protective case comprising:

a housing having four side walls disposed about and at right angles to an end wall, said housing also being formed with an end opening opposite said end wall;

ledge means formed within the housing adjacent the side walls thereof, the surfaces of said ledge means facing said end opening providing a planar support for the circuit board;

a first set of resilient fingers formed integrally with an opposed pair of said side walls, said first set of fingers being located in corresponding openings in said pair of side walls and formed to extend towards said end wall along the path of movement of the circuit board as it is being inserted through said end opening towards said ledge means, said first set of fingers terminating in bevelled front faces spaced above said plane of the ledge means;

said first set of resilient fingers extending inwardly of the corresponding side walls and arranged to fit against the outward side surface of the circuit board when its inward side surface is in contact with said ledge means;

a second set of resilient fingers formed integrally with an opposed pair of said side walls of the housing, said second set of fingers being formed in corresponding openings in the respective side walls, said second set of resilient fingers extending towards said end opening in a direction approximately parallel to but opposite to the direction of extension of said first set of resilient fingers, said second set of fingers extending outwardly of said respective side walls with the ends of said second set of fingers spaced from said end opening to provide for mounting said housing to an instrument panel by gripping the panel between a portion of the housing at said end opening and the ends of said second pair of resilient fingers;

whereby all assembly steps for the case, comprising mounting the circuit board in the case and securing the case in a panel, may be performed without resort to separate fastening means or tools.

2. A protective case for an electrical instrument as claimed in claim 1, further comprising:

flange means on the housing around the end opening thereof, to engage said instrument panel to provide for gripping thereof; and

a front cover snap-fitting to the housing flange means over the end opening.

3. A protective case for an electrical instrument of the type including a circuit board to be held firmly fixed therein, the combination comprising:

a molded-plastic housing having side wall means and an end opening for introduction of the circuit board therein;

a snap-in mounting structure for mounting the circuit board within the housing, the mounting structure including;

means molded within the housing forming a ledge presenting a planar surface for supporting marginal portions of one side surface of a circuit board introduced into said housing through said opening; and

at least one pair of resilient fingers molded integrally with said side wall means and extending along the path of the circuit board as it moves inwardly from said end opening, said fingers being located in respective openings in opposite side walls of the housing, said fingers extending in a direction away from said end opening and terminating in front faces spaced above the plane of said ledge means and arranged to fit against the outer surface of the circuit board when its inner surface is in contact with said ledge, the resilient fingers being formed with an inward cant so that they are engaged and flexed outwardly by the side edges of the circuit board as the board is introduced into the housing through said end opening and then resiliently flex inwardly as the circuit board clears said front faces so that said front faces fit against and hold said circuit board tightly in position against said ledge, thereby to permit the circuit board to be mounted in said housing automatically upon its introduction therein, without resort to separate fastening means or tools.

4. A protective case for an electrical instrument as claimed in claim 3 wherein said front faces are bevelled and have a succession of steps provided therein for engaging the marginal portions of circuit boards of varying thickness.

5. A protective case for an electrical instrument as claimed in claim 3 wherein said housing is rectangular to receive a rectangular circuit board, said ledge means comprising ledges at each interior corner of the housing, at the intersection of the walls thereof.

6. A protective case as claimed in claim 5, comprising two pairs of opposed resilient fingers.

7. A protective case for an electrical instrument as claimed in claim 6 wherein said two pairs of resilient fingers are rectangular in outline.

8. A protective case for an electrical instrument as claimed in claim 3 further comprising outwardly extending resilient catches for mounting said housing to an instrument panel.

9. A protective case for an electrical instrument as claimed in claim 3 of the type including a circuit board with connector pins extending therefrom, wherein the housing has a rear wall with apertures therein for receiving said connector pins.

10. A protective case for an electrical instrument as claimed in claim 3 further comprising a front cover fitting over the end opening through which the circuit board is introduced.

11. A protective case for an electrical instrument of the type including a circuit board to be held firmly fixed therein, the combination comprising:

a rigid housing having side wall means and an end opening for introduction of the circuit board therein;

a snap-in mounting structure for mounting the circuit board within the housing, the mounting structure including;

means within the housing forming a ledge presenting a surface for supporting marginal portions of one side surface of a circuit board introduced into said housing through said end opening; and

at least one pair of resilient fingers integral with said side wall means and extending along the path of the circuit board as it moves inwardly from said opening, said fingers being located in respective openings in opposite side walls of the housing, said fingers extending in a direction away from said end opening and terminating in front faces spaced above said ledge means and arranged to fit against the outer surface of the circuit board when its inner surface is in contact with said ledge, the resilient fingers being formed with an inward cant so that they are engaged and flexed outwardly by the side edges of the circuit board as the board is introduced into the housing through said end opening and then resiliently flex inwardly as the circuit board clears said front faces so that said front faces fit against and hold said circuit board tightly in position against said ledge means, thereby to permit the circuit board to be mounted in said housing automatically upon its introduction therein, without resort to separate fastening means or tools.