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Description  |
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BACKGROUND OF THE INVENTION
(a) Field of the Invention
This invention relates to an improvement in or relating to an information
card such as cash card, which is adapted to identify an individual or
organization in accordance with security code information such as a
combination of numbers, letters and/or the like to be input from the
exterior and to store an input signal or process the input signal by a
semiconductor device built in the card and store the thus-processed
information therein or to generate an output signal in response to the
input signal.
(b) Description of the Prior Art
In recent years, microprocessors, non-volatile memories and the like
devices have been applied to information cards of the above type. As
semiconductor chips for such devices, MOS-type semiconductor chips are
most common. However, a MOS-type semiconductor chip is accompanied by a
drawback that it is very susceptible to electrostatic breakdown. Thus,
such an information card has involved a problem that a semiconductor
device or semiconductor devices built in the card are broken by, for
example, rubbing the card with clothing, thereby rendering the card
unsuitable for actual use.
SUMMARY OF THE INVENTION
This invention contemplates to solve the above problem of the prior art
information cards. Accordingly, an object of this invention is to provide
an information card whose built-in semiconductor chips are safely
protected from electrostatic breakdown.
To achieve the above object of this invention, the characteristic features
of an information card according to this invention resides in that each of
the conductor strips extending from their corresponding contacts of each
semiconductor chip contained in the card makes up an independent circuit
with its corresponding signal input/output terminal when the conductor
strip is brought into contact with the corresponding signal input/output
terminal, but, when the conductor strips are not in contact with their
respective signal input/output terminals, they are electrically connected
with a metallic casing through their respective elastic members, whereby
being mutually connected.
Thus, in one aspect of this invention, there is provided an information
card adapted to identify an individual or organization in accordance with
security code information, to store an input signal therein or to generate
an output signal in response to the input signal and to provide like
functions. The card includes a metallic casing disposed in an opening
which is formed in the card and at least one semiconductor chip seated in
the metallic casing and roofed by a cover film. A conductor strip
extending from each of contacts of the semiconductor chip is disposed in
such a way that it can be brought into contact with a signal input/output
terminal. The information card further comprises an elastic member
provided in said metallic casing at a location corresponding to the
conductor strip and equipped with a magnet at the free end thereof. The
conductor strip is fixedly secured to the metallic casing through an
insulative material. When the conductor strip is spaced apart from the
signal input/output terminal, the conductor strip is kept in contact with
the magnet or elastic member so that it is electrically connected with the
metallic casing through the elastic member, whereby electrically
connecting all conductor strips together and protecting the semiconductor
chip from electrostatic breakdown.
The above and other objects, features and advantages of the present
invention will become apparent from the following description and the
appended claims, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a general information card to which the present
invention relates;
FIG. 2 is a side view of the information card;
FIG. 3 is a fragmentary plan view of an information card according to one
embodiment of this invention;
FIG. 4 is a cross-sectional view taken along line A--A of FIG. 3;
FIG. 5 is a cross-sectional view taken along line B--B of FIG. 3;
FIG. 6 is a fragmentary cross-sectional view showing an information card
according to another embodiment of this invention;
FIG. 7 is a fragmentary cross-sectional view of an information card
according to a further embodiment of this invention;
FIG. 8 is a cross-sectional view similar to FIG. 4 of an information card
of another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
Referring now to the accompanying drawings, certain preferred embodiments
of the present invention will be described. FIGS. 1 and 2 illustrate an
example of information cards to which the present invention relates. An
information card 1 is constituted by a card base 10, a metallic casing 12
disposed or embedded in an opening 11 which is formed at a suitable
location in the card base 10, one or more semiconductor chips enclosed in
the metallic casing 12, and other members related thereto. The card base
10 is made of a plastic material or the like, similar to conventional
information cards, and the metallic casing 12 is made of an electrically
conductive material such as a copper plate or the like. However, the
concept of the casing 12 includes a casing comprising a metallic bottom
plate and surrounding walls made of non-metallic material such as ceramics
or plastics, because such a casing has the same function as a wholly
metallic one. In the illustrated example, the opening 11 and metallic
casing 12 are formed both into rectangular shapes in plan. Needless to
say, they may however be formed into circular or any other suitable
shapes.
FIGS. 3 through 5 depict an embodiment of this invention. In this
embodiment, two semiconductor chips S are disposed in the metallic casing
12, one of which is used as a microprocessor to make a verification of the
card holder and also to protect the data and program, which are used for
the processing of transactions, from any unauthorized alteration, and the
other of which is employed as a memory. As shown in FIG. 4, the front face
of the card base 10 is covered with a cover film 13 while its back face is
also covered by a similar cover film 14. In this illustrated embodiment,
conductor strips 16 extending from their corresponding eight pieces of
contacts 15 of the semiconductor chips S are designed to be brought into
contact with their corresponding signal input/output terminals 17, which
are provided separately from the information card 1. Thus, the front cover
film 13 defines, at locations corresponding to the conductor strips 16,
apertures 18 so that the signal input/output terminals 17 can contact to
the conductor strips. The terminals will contact the strips therethrough
or, as well known, will contact a part 16' integrally formed on the
conductor strips, the part filled in the aperture 18. FIG. 8 depicts a
form provided with part 16' of the strips filled in the aperture 18.
As illustrated in FIG. 4, the interior of the metallic casing 12 is
suitably partitioned. The semiconductor chips S are arranged in the middle
section of the interior. The chips S are fixedly secured on the bottom
wall of the metallic casing 12 through their respective
electrically-conductive pastes 19. The conductor stip 16 from each contact
15 is made of a thin strip-like material such as for example a copper foil
and extends astride its corresponding cavity 20 formed in the metallic
casing 12 aside the semiconductor chips S. The conductor strip 16 is
fixedly secured to a given location of the metallic casing 12 through an
insulative material 21. Also as shown in FIG. 4, an elastic member 22 is
provided in the cavity 20 at a location corresponding to each of the
conductor strips 16. In the illustrated embodiment, leaf springs are
provided. One end of each leaf spring 22 is fixed to the bottom wall of
the metallic casing 12, while the other end, i.e., the free end thereof is
provided with a magnet 23. These leaf springs 22 are made of a suitable
electrically-conductive material. They are kept in an elongated state, as
shown in FIG. 4, when the signal input/output terminals 17 provided with a
measurement head(not illustrated) are not in contact with, in other words,
are apart from their corresponding conductor strips 16. Thus, all the leaf
springs 22 are kept in contact with their corresponding conductor strips
16. Accordingly, all the conductor strips 16 are electrically connected
with the metallic casing 12 through their respective leaf springs 22,
thereby mutually connecting all the conductor strips 16 through the
metallic casing 12. By the way, numeral 24 in FIG. 4 indicates a
passivation glass film enclosing each of the semiconductor chips S.
When the information card 1 is placed at a prescribed position to activate
same, the measurement head comes down to cause its signal input/output
terminals 17 at locations of their corresponding apertures 18 formed
through the cover film 13, to contact with their corresponding conductor
strips 16. At the same time, electromagnets 25 provided with the
measurement head are magnetized, thereby applying a repulsive force to the
magnet 23 provided at the tip of each leaf spring 22 by virtue of a
repulsion action caused by the magnetic force of its relevant
electromagnet. As a result, the free end of each of the leaf springs 22 is
displaced downwardly as shown by phantom lines in FIG. 4 and thus
separated from its corresponding conductor stip 16. This renders the
conductor strips 16 isolated from one another, thereby establishing an
independent circuit for each of the conductor strips 16.
In addition, a specific conductor strip, for example, a conductor strip 16a
at a position designated by "GND" in FIG. 3 is always grounded. Therefore,
as shown in FIG. 5, there is no elastic member 22 provided at a location
corresponding to the above specific conductor strip 16a. The conductor
strip 16a is connected to the metallic casing 12 by a conductor 26 which
extends through at least one of the layers 21 of an insulative material.
Thus, the conductor strip 16a is grounded through the metallic casing 12.
In FIG. 3, "CLOCK" indicates a conductor strip for signals to control the
activation of the semiconductor device, "5V" a conductor strip for a power
supply of the semiconductor device, "24V" a conductor strip for a power
supply for writing-in, reading-out, erasure, etc. of information stored,
and "EXTRA" a space terminal.
In the above embodiment, leaf springs are used as elastic members. Although
use of such leaf springs are generally preferred and the elastic members
are supposed to be electrically conductive, they are not necessarily leaf
springs. As shown in FIG. 6, coil springs may function in the same manner
as the leaf springs. Furthermore, as illustrated in FIG. 7, electrically
conductive rubber 22' may also be used as an elastic member. In this case,
one end portion of an electrically conductive magnet 23 is embedded in the
rubber 22' and the other end portion of the magnet 23 is allowed to
contact with the conductor strip 16. When activating the information card
1, the rubber 22' is compressed by the repulsive force of the magnet,
thereby separating the magnet 23 from the conductor strip 16. In some
instances, parmanent magnets may be used in lieu of the electromagnets 25.
Accordingly, the measurement head for activating an information card
according to this invention is provided with a suitable number of magnets
25, whereby rendering each conductor strip 16 to form an independent
circuit during the activation of the information card. However, prior to
an activation, the conductor strips of the information card are
electrically connected with the metallic casing by means of their
corresponding elastic members or elastic members and magnets disposed in
the metallic casing, thereby mutually connecting all the conductor strips
and allowing them to have the same potential. Accordingly, the
semiconductor chips will not be affected by electrostatic energy and can
thus be protected from electrostatic breakdown even if they are subjected
to such electrostatic energy due to rubbing of the information card or the
like.
Therefore, it will be possible to provide information cards of extremely
high utility when the present invention is applied to information cards
containing one or more semiconductor chips of the MOS-type structure.
Having now fully described the invention, it will be apparent to one of
ordinary skill in the art that many changes and modifications can be made
thereto without departing from the spirit or scope of the invention as set
forth herein.
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