Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1998-07-30
2001-11-20
Lee, Michael G. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S439000, C015S001510, C015S210100
Reexamination Certificate
active
06318632
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally pertains to removing electrostatic charge from a non-conductive object that is inserted into a port or receptacle. The present invention also generally pertains to smart card readers, and more particularly, but not by way of limitation, to a card reader for eliminating problems with electrostatic discharge that often occur when a non-conductive smart card is inserted into a card reader.
HISTORY OF THE RELATED ART
Credit cards have long been an accepted part of life around the world. Early credit cards had identifying information raised from the remainder of the card, and the identifying information was transferred from the card by the use of pressure and carbon paper. More modern credit and debit cards have their identifying information as fixed electronic data, such as a scanable magnetic strip embedded on the surface of a card. Such identifying information exists within the card in a read-only format. Smart cards, the most recent advancement in the card art, utilize an active integrated circuit embedded within the card to store identifying information. Unlike prior art cards, smart cards have the additional capability of altering the identifying information stored in their integrated circuits. Smart cards may be utilized for any function of a prior art credit or debit card and have also proven useful in a wide variety of other functions, including paying bills; paying for mass transit; performing health care benefit transactions; and in using pay telephones, automated teller machines, in-home digital satellite systems, “set top” boxes used with cable television, or other similar equipment.
The integrated circuit in a smart card is typically a memory chip or a microprocessor chip. To provide access to the information stored in the integrated circuit of the card, operative regions such as contact pads are provided on the surface of the card, and the integrated circuit is electrically connected to these operative regions.
A smart card reader typically has a housing having a slot through which the card is inserted and removed. After insertion, the smart card is manipulated into a reading position, in which the operative regions of the card are in contact with certain terminals in the card reader. The terminals of the card reader are typically electrically connected to a printed circuit board containing the additional circuity necessary for a given transaction. After a transaction is complete, the card is returned to the user.
Electrostatic discharge (ESD) frequently creates problems for smart card users. Smart cards are typically made of a generally non-conductive material, such as plastic. However, such generally non-conductive smart cards often have some minimal level of electrical conductivity. Smart cards may also be made of a partially conductive material, such as plastic with a carbon or other conventional conductive filler disposed therein. Normal handling of a card, such as removal and insertion of a card from a user's wallet or billfold, may cause electrostatic charge to build up in the card. When a user inserts a card into a smart card reader, and when the card comes into contact with the conductive terminals of the card reader, electric shock may occur. This electric shock is similar to the shock that occurs when one walks across a carpeted floor and then touches a metal object such as a lamp. Such shock may damage or cause malfunction of the integrated circuit within the smart card, and it may also damage or cause malfunction of the circuitry on the printed circuit board to which the card reader is electrically connected.
In addition, after a period of use, body oils or other partially conductive material may collect on the surface of a
smart card. Such conductive material may be sufficient to transfer electrostatic charge built up on the user of a card to the card itself. Such additional electrostatic charge exacerbates the ESD problems experienced by smart cards.
Several prior art techniques have been formulated to address the ESD problem of smart cards. For example, it is known to provide a smart card reader with a cover or top portion made of a conductive material and to connect the cover to ground. During insertion, a smart card contacts the cover before it contacts the conductive terminals connected to the base or bottom portion of the smart card reader. In this way, electrostatic charge may be discharged through the cover to ground, and a damaging electric shock is avoided. U.S. Pat. No. 5,380,997 assigned to Alcatel Radiotelephone discloses such a technique.
In addition, it is known to form a card reader cover from a highly resistive, yet conductive material and to ground the cover to a chassis. Alternatively, it is also known to paint or coat the cover of a card reader with a highly resistive, yet conductive material and to ground the painted cover to a chassis. Such materials provide a relatively slow discharge rate for the electrostatic charge, in contrast to the relatively fast discharge rate of a damaging electric shock. Furthermore, a variety of conventional conductive plastics providing ESD protection and electromagnetic interference shielding are sold by the Bekaert Corporation of Marietta, Ga. under the BEKI-SHIELD trademark.
U.S. application Ser. No. 08/843,735 filed Apr. 21, 1997, which is commonly owned with the subject application and is incorporated herein by reference, discloses several advantageous techniques to ground a smart card reader and to insure proper electrical isolation of the electrical components therein. The grounding techniques disclosed in U.S. application Ser. No. 08/843,735 involve the use of highly resistive, yet conductive materials for the cover or base of a smart card reader.
Each of the above-referenced techniques may be generally described as a “conductive discharge technique”. Conductive discharge techniques require a conductive member to physically touch a charged object and provide a path to ground through which current may flow in order to remove the electrostatic charge from the object. For current to flow, both the charged object and the path to ground must be at least partially conductive. Objects that are extremely non-conductive, such as, by way of example, objects that have a surface resistivity substantially above 1×10
10
, ohms/sq (ohms/square), and most typically in the range of about 1×10
14
ohms/sq to about 1×10
15
ohms/sq, cannot be discharged in this manner because they will not allow sufficient current to flow through the objects themselves, even though the path to ground may be extremely conductive.
In many cases, the plastic materials used to manufacture conventional smart cards are extremely non-conductive. Electrostatic charge may build up in such cards, as described hereinabove, and such charge may induce an opposite charge on nearby conductive parts, such as a conductive member in a card reader into which the card is inserted. Such inducement does not discharge the card itself because current does not flow from the card, and the induced charge on the conductive member in the smart card reader may remain after the card is removed from the reader. The induced charge may “arc”to other conductive members within the smart card reader, causing electric shock damage to the card reader or the circuitry of the printed circuit board to which the card reader is electrically connected. In addition, when another smart card is subsequently inserted into the card reader and comes close to, or in contact with, the conductive member in which the induced charge exists, electric shock may also damage or cause malfunction of the integrated circuit within the smart card. Therefore, a need exists in the card reader industry for a simple, low cost technique of safely and efficiently removing electrostatic charge from smart cards made from a non-conductive material, and especially an extremely non-conductive material.
SUMMARY OF THE INVENTION
One aspect of the present invention comprises a smart card reader including a housing having a slot
Folta Claude Grant
Grant John Lincoln
Airborn, Inc.
Fureman Jared J.
Jenkens & Gilchrist a Professional Corporation
Lee Michael G.
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