Registers – Records – Conductive
Reexamination Certificate
1999-03-31
2001-10-09
Frech, Karl D. (Department: 2876)
Registers
Records
Conductive
C235S487000
Reexamination Certificate
active
06299070
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a data carrier used in a non-contact identification system and the method by which it is produced.
BACKGROUND OF THE INVENTION
Data carriers (ID tags) which maintain data in non-contact identification systems continue to be miniaturized, and the current focus is on producing a smaller, cheaper data carrier which is suitable for a variety of applications. These might include access control systems which allow a person with a data carrier or ID tag to enter, uniform collection systems for hospitals or restaurants, and tracking systems to keep track of articles of clothing at cleaners or laundries. Data carriers which are to be attached to clothing for laundry identification must be waterproof and heat-resistant so that they will not be damaged during cleaning. Because they are used for such a variety of applications, it is essential that data carriers be mass-produced as cheaply as possible, in the fewest possible processes, and in the shortest possible time.
We shall now explain the existing methods of producing data carriers. A first method is shown in FIG.
7
. Toroidal antenna coil
102
is placed in case
101
. An electronic circuit unit (hereafter referred to as functional component
104
) which contains a packaged IC is placed on printed circuit board
103
in case
101
. The spaces are then filled with a resin
105
, such as an epoxy resin or the like, to complete the data carrier.
A second method used to produce data carriers is transfer molding, which is illustrated in FIG.
8
. Antenna coil
102
and functional component
104
, which is connected to the antenna coil, are supported in a chamber inside molds
111
and
112
. The chamber is filled via a narrow gateway with a thermosetting resin, such as epoxy resin, and the assembly is heated for several minutes to set the resin.
A third method used to produce data carriers is press molding. As shown in FIG.
9
(
a
), a data carrier unit consisting of antenna coils
102
and functional component
104
is sandwiched between sheets
121
and
122
of vinyl chloride (PVC) and press-molded. Once pressed, as can be seen in FIG.
9
(
b
), the work becomes a flat plate
123
. Then, as is illustrated in FIG.
9
(
c
), round plugs are punched out of the plate to produce two flat data carriers.
A fourth method uses injection molding to seal the data carrier. In this method, as is shown in FIGS.
10
(
a
) and (
b
), a data carrier unit consisting of antenna coil
102
and functional component
104
is inserted into tray
131
, which is produced by a molding process. Two of these assembled trays are then placed in the depressions in lower mold
132
. Then, as is shown in FIG.
10
(
c
), the lower mold is covered with upper mold
133
, which also has two depressions in the locations which correspond to those in the lower mold. A thermoplastic resin is then injected at high pressure via the gates in upper mold
133
to form two button-shaped data carriers.
The above-described methods used in the prior art to produce data carriers are subject to the following problems regarding the water-resistance of the carriers and their ability to be mass-produced. With the resin-filling method shown in
FIG. 7
, the spaces must be filled slowly to prevent air bubbles from occurring. In addition to the care required in filling the spaces with resin, this method requires several hours for the resin to set.
The transfer-molding method shown in
FIG. 8
entails pressure-molding for several minutes, and it requires that the resin be cured by maintaining it at a high temperature for several hours or longer. Also, the high pressure required to seal the functional component in resin makes it liable to slip out of position. FIG.
11
(
a
) shows the correct placement of antenna coil
102
and functional component
104
. When the spaces in the mold are filled with resin, these components have a tendency to slide out of the center of the data carrier. The displacement of the functional component within the molded unit is not the only problem with this method. As can be seen in FIG.
11
(
b
), antenna coil
102
and functional component
104
may also protrude from the surface of the resin seal.
In the press-molding method shown in FIGS.
9
(A)-(C), a punch process is required after the work is pressed to produce a round flat carrier. This extra process requires additional time and effort. And since only a vinyl chloride or another resin with low heat resistance can be used for the sheet material, this method cannot be used to produce heat-resistant data carriers.
The injection molding method produces a data carrier in a short time; however, just as in transfer molding, the high pressure required tends to force the functional component out of its proper position. And because it is injected under such high pressure, the resin may damage functional component
104
when it strikes it dead center, as shown in FIG.
12
(
a
). For these reasons, manufacturers tend to inject the resin at a lower pressure, which results in a rougher-textured product that is easier to damage. Also, a parting compound is added to the resin so that the finished data carrier can be removed from the mold easily. Repeated incidences of heat shock may cause cracks to occur in surface
135
where seal
134
is in contact with tray
131
. Since this may result in the seal separating from the tray, the injection method cannot guarantee a hermetic seal.
Although the injection mold has small air exhaust channels in it, if the components in it have a more complex shape, air pockets may form between the functional component and tray
131
, as shown by the dotted lines in FIG.
12
(
b
). If the work is molded at high temperature with these air pockets in it, the air will push tray
131
away from the functional component, and it will not be possible to achieve the specifications for which the mold was designed.
As can be seen in FIG.
13
(
a
), the lead cable
102
a
of antenna coil
102
is normally passed under the body of the coil and connected to the functional component during injection so that it will not be damaged. Nevertheless, the injection pressure applied to antenna coil
102
may damage the insulation on the lead cable
102
a.
If this happens, the inductance and the resonant frequency will deviate from their specified values and the data carrier will not maintain its characteristics.
SUMMARY OF THE INVENTION
This invention alleviates the shortcomings of prior art devices discussed above. The object of this invention is to provide a data carrier which can be produced economically in a short time, which has superior mass-production characteristics, and which is highly resistant to water and heat, and to provide a production method by which such a data carrier can be produced.
The data carrier according to this invention is distinguished by at least the following features. It has an antenna coil; a functional component consisting of an electronic circuit unit connected to both ends of the antenna coil; a tray with a cylindrical portion having a first depression in its surface and a second annular-shaped depression which surrounds the cylindrical portion, and which supports, in the first and second depressions, the aforesaid functional component and antenna coil. A cap is installed over the aforesaid cylindrical portion to cover the aforesaid functional component, and a seal created by injection molding seals the aforesaid tray and upper portion of the cap.
The production method for a data carrier according to this invention is distinguished by the following steps. Firstly, a functional component consisting of an electronic circuit unit is connected to both ends of an antenna coil. A tray is, then, molded which has a cylindrical portion with a first depression in its surface and a second annular depression surrounding the central portion. The functional component and the aforesaid antenna coil are, then, inserted into the respective depressions in the aforesaid tray. A cap is, then, installed from above the aforesaid cylindrical portion so
Foley & Lardner
Frech Karl D.
Omron Corporation
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