Registers – Records – Conductive
Reexamination Certificate
2003-04-10
2004-09-21
Le, Thien M. (Department: 2876)
Registers
Records
Conductive
Reexamination Certificate
active
06793144
ABSTRACT:
TECHNICAL FIELD
The present invention relates to communication interfaces for smart (IC) cards. In particular, the present invention relates to means that enable smart cards to communicate with a host through a universal serial bus (USB) connection in either full-speed or high-speed mode.
BACKGROUND ART
Smart cards typically communicate with a host terminal through a reader. In one type of system, the reader is also the host. In such system, the card is inserted into a slot in the reader, which brings electrical contacts in the reader into engagement with mating contacts on the exterior of the card. The engaged contacts enable a microcontroller in the reader to communicate with the memories and/or microprocessor in the smart card. Presently, most smart cards communicate with card readers in a manner compliant with the International Standards Organization/International Electrotechnical Commission (ISO) 7816.
FIG. 1
is a block diagram showing the construction and connections of a stand-alone reader
10
and a smart card
12
connected according to a typical ISO-7816 connection scheme. Of the eight contact points available on a typical smart card system, the typical connection made use of five contact points: one for power supply, one for clock signal, one for data input/output, one for sending reset signals, and one for ground connection. A microprocessor
14
in the reader
10
receives clock signals from a clock
22
and inputs/output signals through the I/O line
24
and reset signal through the RST line
26
.
Although the ISO-7816 is a well established and widely used standard, communication based on this standard is rather slow. Furthermore, as personal computers become ubiquitous and Universal Serial Bus (USB) connection a standard features in most PCs, smart card reader can be made cheaper by relocating the micro-processing and memory functions from the reader (the card contacting mechanism) to a separate host PC, so that the reader becomes a simple USB connector. The USB protocol is a private industry standard sponsored by USB Implementers Forum, Inc., a joint initiative of Intel, Hewlett-Packard, Lucent, NEC, Philips, Microsoft and others. The protocol works in conjunction with the IEEE 1394 standard connector.
FIG. 2
is a block diagram that shows a typical construction and connections of a smart card reading system that utilizes a computer and a USB connection. In
FIG. 2
, a personal computer
40
communicates with a smart card
46
via a USB cable connection
42
with a connector head
44
(the “card reader”), which calls for 4 wires: one for the power Vcc, one for the ground GND, and a pair of differential data transmission wire DATA+
50
and DATA−
52
. A first generation USB standard (version 1.1) allows transmission in two modes: a low speed mode and a full speed mode. For low speed transmissions, such as Control Transfer and Interrupt Transfer under USB 1.1, the data is clocked within the computer
40
at 1.5 Mbps with a data signaling tolerance of ± 1.5% (or 15,000 ppm). For full speed transfer such as Isochronous Transfer or Bulk Transfer under USB 1.1, the data is clocked at 12 Mbps with a data signaling tolerance of ± 0.25% (or 2,500 ppm). In addition to the two modes mentioned above, a newer USB standard (version 2.0) calls for a third (high speed) transmission mode where the data signaling rate is set at 480 Mbps with a data signaling tolerance of ± 500 ppm.
At any given speed of transmission, because the USB cable
42
does not have a separate wire to carry a clock signal, a clock generator has to be present at both ends of the cable
42
. At the host end, most readers and computer systems have a highly accurate system clock
60
that can be use for both reception and transmission purposes. At the card end of the cable
42
, a low cost electronic resonator
48
could be used for low speed transmission. Such resonators
48
are typically integrated into the smart card's microprocessor
58
, as shown in FIG.
2
. However, such a low cost resonator
48
is not accurate enough to clock transmissions at either full speed or high speed. Presently, in order to have a full speed or high-speed transmission system, an accurate clock element, such as a crystal oscillator, has to be introduced into the reader/connector.
FIG. 3
shows a typical high speed USB reader/connector
44
that connects a highly accurate clock element
62
to one of the contact pins
60
. Earlier generations of USB smart card connectors lacking an accurate clock element (
FIG. 2
) would become obsolete. However, since there is still a large installed base of low speed USB smart card connectors, it would be desirable to have a smart card that can use any of these connectors in a full speed or high speed transmission mode, regardless of whether the connector
44
has or does not have a clock inside.
Since having a clock element in the reader/connector adds complexity and thus cost to the manufacturing of the reader/connector, it would also be desirable to have a smart card system that eliminate the need for a clock element in the reader/connector module.
DISCLOSURE OF INVENTION
The present invention is a smart card that has a highly accurate clock element connected to its microprocessor. The incorporation of an accurate clock element enables the smart card to be used with any USB enabled smart card readers/connectors for either full speed or high-speed data transmission. The accurate clock element can be a clock ceramic oscillator, a resonator, or any vibrating device, provided that it has an accuracy sufficient to achieve at least full speed, and preferably also high speed, data transfer (e.g., an accuracy of at least 0.25%) and a thickness meeting standards for placement on smart cards (e.g., preferably not more than 0.6 mm).
REFERENCES:
patent: 5712472 (1998-01-01), Lee
patent: 6168077 (2001-01-01), Gray et al.
patent: 6199128 (2001-03-01), Sarat
patent: 6343364 (2002-01-01), Leydier et al.
patent: 6439464 (2002-08-01), Fruhauf et al.
patent: 6543690 (2003-04-01), Leydier et al.
patent: 6557754 (2003-05-01), Gray et al.
patent: 2001/0011914 (2001-08-01), Pomet
patent: 2001/0055202 (2001-12-01), Templeton et al.
patent: 2002/0049887 (2002-04-01), Takahashi
patent: 2003/0155424 (2003-08-01), Guion et al.
patent: 99/48039 (1999-09-01), None
patent: 99/49415 (1999-09-01), None
patent: 00/16255 (2000-03-01), None
patent: WO 00/23936 (2000-04-01), None
patent: 01/69881 (2001-09-01), None
patent: WO 02/11081 (2002-02-01), None
Webpage printout, Certified USB™, Introduction to USB On-the-Go, 1 page.
Website printout, Certified USB™, “Developers”, 3 pages.
Website printout, Intel, “A Technical Introduction to USB 2.0”, 6 pages.
Guez Gregory
Peytavy Alain
Atmel Corporation
Le Thien M.
Nowlin April
Protsik Mark
Schneck Thomas
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