Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-09-24
2001-06-05
Gandhi, Jayprakash N. (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S753000, C361S801000, C361S802000, C024S522000, C254S104000, C403S409100
Reexamination Certificate
active
06243271
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to positioners for electronic cards, in general and, in particular, to positioners for mounting electronic cards precisely in their slots.
BACKGROUND OF THE INVENTION
Electronic and communications systems generally include a chassis having a plurality of slots for receiving electronic cards, for example, printed wiring boards (PWB), also known as printed circuit boards (PCB). The cards are inserted into the slots, substantially parallel to one another. The slots are manufactured by high precision machinery and have very precise dimensions, e.g., width of tolerance ±0.05 mm. While it is possible to manufacture electronic cards having very precise thickness, it is very expensive. Hence, the thickness of the cards to be inserted into the slots generally varies greatly. For example, for a nominal thickness of 1.60 mm, the thickness of the cards can range from 1.36 mm to 1.86 mm. The result is that the cards inserted into the slots are loosely retained in the track and not precisely positioned, which is problematic in many electronic systems. In addition, the cards themselves are flexible, and can be twisted as much as 1% during the manufacturing. This problem is particularly serious in high frequency telecommunications systems, where inaccurate seating between adjacent cards can cause random air gaps and consequent radio frequency interference (RFI) problems.
There are known in the art a number of spacer elements which serve to hold adjacent cards affixed to one another at a predetermined distance, such as those shown in U.S. Pat. Nos. 3,983,459 and 4,444,318, and 4,604,776. These maintain a fixed minimum distance between adjacent cards, but are not designed to provide, and do not ensure, consistent alignment.
There are also known retention elements for retaining the cards in their slots, such as a ball with a spring, or a leaf spring mounted on the bottom and/or top of the card. These devices provide controlled spacing by pressing against the wall of the slot. However, these springs are not fixed, so they tend to wear rapidly and cease functioning under frequent insertion and removal of the card. They also lack the necessary strength to maintain a card in a fixed position, when opposed by RFI gaskets. There are also known wedges for inserting between the slot and the card to provide thermal transfer and to control vibration. But these wedges are expensive to manufacture.
Accordingly, there is a long felt need for a simple, inexpensive device to ensure precise placement of electronic cards in their slots.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a positioner for an electronic card in a slot including a head and at least one leg, the height of the positioner being substantially equal to the width of the slot, the leg being arranged for insertion into an aperture through the electronic card, the bottom of the leg being arranged for alignment with a reference plane of the electronic card and to contact a wall of the slot.
According to a preferred embodiment, one of the legs is shaped to easily fit one of the apertures, thereby properly locating the positioner, and the second leg is shaped for frictional engagement of the second aperture.
According to a most preferred embodiment of the invention, the positioner is formed for blind insertion into the apertures in the electronic card.
According to another preferred embodiment, the leg of the positioner is arranged for alignment with the reference plane on the component side of the electronic card.
According to still another embodiment, the slot is narrower at the back than at the front, and the height of the positioner is substantially equal to the width of the slot near the back.
There is also provided in accordance with the present invention an electronic card for sliding into a slot, the electronic card including a board having a reference plane on the component side and on the print side, and at least one aperture through a margin of the electronic card, a positioner seated in the aperture, the positioner including a head and at least one leg, the height of the positioner being substantially equal to the width of the slot, the bottom of the leg being substantially aligned with a reference plane on the electronic card, the leg being arranged for insertion into the aperture.
There is further provided in accordance with the present invention a method for seating an electronic card in a slot including the steps of providing at least one aperture through a margin of the electronic card, and inserting a positioner including a head and at least one leg, the height of the positioner being substantially equal to the width of the slot, into the aperture until the bottom of the leg is substantially aligned with a reference plane on the electronic card.
REFERENCES:
patent: 3983459 (1976-09-01), Passler
patent: 4444318 (1984-04-01), Alexander
patent: 4589794 (1986-05-01), Sugiura et al.
patent: 4604776 (1986-08-01), Takahashi
patent: 4914552 (1990-04-01), Kecmer
patent: 4969065 (1990-11-01), Petri
patent: 5204496 (1993-04-01), Boulay et al.
patent: 5224016 (1993-06-01), Weisman et al.
patent: 5336110 (1994-08-01), Mosquera
patent: 5485353 (1996-01-01), Hayes et al.
patent: 5539149 (1996-07-01), Gatti
Brown & Raysman Millstein Felder & Steiner LLP
ECI Telecom Ltd.
Gandhi Jayprakash N.
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