Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Utility Patent
1997-10-24
2001-01-02
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S752000, C361S753000, C361S754000, C361S756000, C361S759000, C361S796000, C361S797000, C361S798000, C361S799000, C206S706000, C211S041170, C211S201000
Utility Patent
active
06169662
ABSTRACT:
BACKGROUND OF THE INVENTION
Computer systems typically include a computer chassis which houses a plurality of printed circuit board assemblies (PCAs) which are electrically coupled to each other. During the lifetime of the computer system, it is often necessary to add, replace or remove a PCA from another PCA, i.e. the system PCA, see FIG.
1
. For example, a particular PCA may be defective or an older version of a PCA may need to be replaced with an updated version of the PCA card that has more powerful features. To prevent system disruption, oftentimes it is preferable to remove the PCA card while the remainder of the PCA cards in the computer system backplane are powered on.
Unfortunately, PCA card removal is not always easy. The backplane PCA connector which receives the edge of the individual PCA card, often has a high extraction force for PCA card removal. Although this high extraction force (1) helps prevent accidental removal of the PCA card and (2) helps to provide solid mechanical and electrical connection of the PCA to the computer system, the high extraction force makes PCA card extraction difficult. The difficult removal of the PCA card is exacerbated by the fact that PCA cards are often closely spaced giving the system user removing the PCA card little room for maneuverability.
Often, because of the problems associated with removing the PCA card, the system user drops or scrapes the PCA against a neighboring PCA. In a powered down computer system, dropping the PCA against a neighboring PCA can cause component damage. In a powered on system, dropping or scraping of the PCA against a neighboring PCA can cause electrical shorting.
Another problem resulting from the difficulties in removing PCA is the incidence of scrapes or cuts to the fingers of the individual removing the PCA. Current PCA manufacturing processes result in sharp component leads. Because of the high force required to remove the PCA, it is difficult for the system technician to maintain his or her hand position and frequently the hand position of the technician removing the PCA will slip to coincide with a sharp edge of the component lead. This slippage often results in a scrape or cut on the fingertips of the individual attempting to remove the PCA card.
A method for removing PCA cards which allows for the easy removal of an individual PCA card in a powered-on computer system while minimizing the damage (1) to the PCA cards remaining in the system and (2) to the individual removing the PCA card is needed.
SUMMARY OF THE INVENTION
The present invention provides a system and method for providing easy removal of a PCA card from a powered on computer system while minimizing the risk of damage to the computer system and the risk of injury to the individual removing the PCA card. The printed circuit assembly card removal system is comprised of: an ejection card including at least a first ejector extending from the surface of the ejection card, the ejector having a first surface for pressing against the edge of the PCA card to be removed, and an ejection card holder for mechanically supporting the ejection card. Preferably, the ejection card holder further includes at least one ejection card stop which controls the travel distance of the ejection card and which prevents the ejection card from becoming accidentally disengaged from the ejection card holder.
In the preferred embodiment, the card removal system includes a pair of spaced apart ejectors and a pair of spaced apart ejection card stops. Typically an ejection card holder is placed on each side of the PCA connector for the card to be removed. Each ejection card holder includes a recess for holding an ejector and a recess for holding an ejection card stop.
The ejector pair and ejection card stop pair of the ejection card are installed in the ejection card holders before the PCA card is removed. Since the width of the ejection card holder is preferably less than the width of the PCA connector into which the PCA card is inserted, the first surface of the ejector is behind the edge of the PCA card to be removed.
After the ejection card has been installed into the ejection card holder, the PCA card (that is eventually to be removed) is inserted into a PCA connector. To remove the ejection card, the system technician pulls outwardly on the ejection card grip away from the ejection card, the system technician pulls outwardly on the ejection card grip away from the ejection card holders. When the ejection card is pulled outward, the ejector applies a force to the edge of the PCA card to be removed, forcing the card edge fingers of the PCA card to become disengaged from the PCA connector. Typically, the ejection card will drop downward onto the surface of the ejection card where it can be easily removed.
Because each PCA card has a corresponding ejection card that is positioned underneath it, typically when a PCA card is removed, the PCA card drops onto the ejection card located beneath it. Thus an ejection card physically separates the PCA to be removed from its neighboring PCA card, preventing mechanical damage to its neighboring PCA card. For an on line replacement of a PCA card, the system is powered on, but the particular PCA card that is being added or removed may be powered on or may be powered off. Because the ejection card is typically comprised of an insulator, each ejection card prevents the electrical shorting out that occurs in conventional system when a PCA comes into physical contact with its neighboring PCA. Thus, the ejection card prevents the mechanical damage or electrical shorting that can occur when the PCA board is removed from a powered on system.
In the card removal system taught by the present invention, the PCA is removed by pulling outward on the card grips of the ejection card instead of pulling outward on the PCA card targeted for removal. Gripping the ejection card instead of the PCA card solves the problem of injuries from component leads which occurs when an individual tries to remove a PCA card from a conventionally configured system. Another advantage of removing the PCA card using the ejection card is that the individual trying to remove the PCA no longer has to try and squeeze his fingers between PCA cards, a space of limited maneuverability.
Another advantage of the present invention is improved alignment of the PCA card. The preferred embodiment of the card removal system includes a plurality of alignment pins that extend from the sidewall of the computer system chassis adjacent to the PCA bulkhead. The alignment pins help facilitate the proper alignment of the PCA card on insertion and upon removal. On insertion the system technician simply slides a groove formed in the PCA bulkhead over the alignment pins to assist in proper positioning of the PCA card. When removing the PCA card, the alignment pin helps keep the PCA card from rotating during removal. This is especially important when a short PCA card, a PCA card that extends only the length of the PCA connector, is removed.
A further understanding of the nature and advantages of the invention described herein may be realized by reference to the remaining portion of the specification and the attached drawings.
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“Option Card Retainer”, IBM Technical Disclosure Bulletin, US, IBM Corp., New York, vol. 31, No. 6; Nov. 1, 1988, pp. 251-252.
Clark Thomas J.
Sandoval Alisa C.
Dinh Tuan
Hewlett--Packard Company
Lee Denise A.
Picard Leo P.
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