Wireless tag, its manufacturing and its layout

Details Wireless tag, its manufacturing and its layout Wireless tag, its manufacturing and its layout

2000-05-24

2003-05-13

Wong, Don (Department: 2821)

Communications: radio wave antennas

Antennas

Microstrip

C343S829000, C343S830000

Reexamination Certificate

active

06563463

ABSTRACT:

The present invention relates to a wireless IC tag using a radio frequency of sub-microwave band and having no battery. A detailed description is given of a conventional wireless IC tag using the radio frequency band and having no battery in Shinichi Haruyama, “Technologies for microwave ID card system”, the supplement of Japanese magazine “Transistor -Gijujtsu” published by CQ Publishing Co. Ltd., pp. May 21-29, 1992. In a rectenna (circuit comprising an antenna and a rectifying circuit) of a wireless IC tag described in the paper, there is introduced an antenna as shown by FIG:
1
comprising a series connection of a half-wavelength resonator and a shottky barrier diode.
FIG. 1
shows the rectenna circuit, numerals
1
and
2
designate quarter-wavelength antennas, numeral
3
designates a shottky barrier diode, numerals
4
and
5
designate inductors, numeral
6
designates a condenser and numeral
7
designates an output terminal. Microwave power received by the ¼ wavelength type antennas
1
and
2
is rectified via the shottky barrier diode
3
and the inductor
5
and is accumulated in the capacitor
6
as direct current and is outputted from the output terminal
7
as necessary. Further, there is described an example of utilizing a rectangular microstrip-patch antenna in AIM Japan, “Technologies and applications for data carrier” published by THE NIKKAN KOGYO SHIMBUN, LTD. pp. Oct. 22-25, 1990.
FIGS. 2A
,
2
B and
2
C show t he example of the rectangular microstrip-patch antenna in which
FIG. 2A
is a plane view,
FIG. 2B
is a side view and
FIG. 2C
shows a rear face. In
FIGS. 2A
,
2
B,
2
C, numeral
8
designates a rectangular patch, numeral
9
designates a dielectric member, numeral
10
designates a ground conductor, numeral
11
designates a feed line and numeral
12
designates a feed point. A microwave signal inputted from the feed line
11
is resonated at a frequency determined by a length “l” of a side of a square shape including the feed point
12
of the rectangular patch
8
. According to these antennas, when the losses of the member is reduced to reduce loss of the antenna, the Q of the resonating circuit becomes high and a matching frequency band is narrowed. When the Q of the resonator is increased, it is difficult to widen the matching frequency band of the antenna
According to a wireless IC tag, voltage generated by rectifying current is changed in accordance with a distance between the wireless IC tag and an interrogator antenna and when the wireless IC tag becomes proximate to the interrogator antenna, the rectifying voltage is rapidly elevated. Therefore, in view of the withstanding voltage of an IC, a voltage value is devised to be maintained at a predetermined value or lower by a voltage limiter comprising transistors connected in multiple stages in Japanese Laid-open Patent (Kokai) No. Hei 8-185497. Further, a result of communicating with the wireless IC tag is produced by data of the wireless IC tag absorbed from the interrogator.
With regard to a structure of a dipole antenna for electrically connecting and packaging an antenna of a wireless IC tag and an IC circuit, in “manufacturing method for wireless tag” disclosed in Japanese Laid-open Patent (Kokai) No. Hei 10-32214, there is described a method of mounting a structure in which an IC is attached to a strip-like antenna having a lead frame structure and an IC attaching portion thereof or a total thereof including the antenna is integrated by a mold technology such as transfermolding.
SUMMARY OF THE INVENTION
According to the conventional technologies, it has been difficult to widen a matching frequency band by promoting a sensitivity of the antenna of the wireless IC tag. It is an object of the present invention to achieve wide band formation without deteriorating the sensitivity of an antenna to thereby facilitate to manufacture the antenna by promoting the yield against the manufacturing dispersion by constituting the wide band formation of the antenna.
It is another object of the present invention to realize a circuit constitution in place of a low voltage circuit maintained at predetermined voltage by wastefully consuming current by using a transistor, a zenner diode or the like, for carrying out operation of confirming transmittance of data between a wireless IC tag and an interrogator by using power dissipated in the previous low voltage circuit without checking and determining by the data of the wireless IC tag read by the interrogator.
It is another object of the present invention to manufacture of a wireless IC tag of an integrated type by filling and molding a mold material of a transfer mold or the like as a dielectric material of an antenna in a microstrip-line constitution while ensuring electric connection between IC and the antenna and ensuring also mechanical strength in the antenna for the wireless IC tag in the microstrip structure comprising a ground conductor plate constituted by a lead frame and an antenna conductor.
In order to widen a matching frequency band without deteriorating the sensitivity of an antenna of a wireless IC tag, there is achieved wide band formation by double tuning by constituting an antenna of a double tuned type in which quarter-wavelength antenna resonators in a microstrip constitution are subjected to mutual inductance coupling by an impedance element comprising a common inductor. For that purpose, there is adopted an antenna structure for grounding a middle point of a half-wavelength antenna by using a through hole conductor with a ground face of a microstrip substrate or a lead frame conductor. There is constructed an integrated structure by mechanically and/or electrically connecting IC to a surface of an antenna constituted by a lead frame conductor on a side of a ground face by using an insulating adhering agent or a conductive adhering agent and pressurizing and solidifying a mold member for transfer mold of the lead frame integrally connected electrically and mechanically to a ground conductor constituted by the lead frame conductor by a conductor for grounding at a middle point of the antenna.
In order to make the rectified voltage generated at the rectenna circuit a constant voltage, according to the present invention, an LED (Light Emitting Diode) is introduced, and constant voltage formation of the circuit is achieved by utilizing the rapid rise of the forward direction voltage of the positive characteristic of the LED. Generated power increased as the wireless IC tag becomes proximate to an antenna of an interrogator, brings about an increase in current in the forward direction of the LED, increases light emitting intensity of the LED and the circuit maintains voltage applied on an IC circuit constituted by CMOS or the like at a predetermined value. The light emitting phenomenon at this occasion indicates that the interrogator makes access to the wireless IC tag or can make access thereto. At this occasion, the IC indicates a drivable state or a driving state and constitutes a criterion of in-operation of recognizing the wireless IC tag or finish of operation by a congestion control. Further, by setting and disposing a logic circuit in the IC circuit, the logic circuit can be used in various signals for positively controlling the light emitting state of the diode and knowing the state of the wireless IC tag via the logic circuit.
By press forming of a lead frame flat plate, the lead frame flat plate is formed in a shape of a cross having a connection conductor with a ground conductor at a middle point portion of a half-wavelength antenna formed in a short strip further formed with a connecting portion for connecting to match with the IC circuit between a middle point of any of the sides and an opening end of the antenna in the longitudinal direction of the antenna, further connected with a circuit of the wireless IC tag or a terminal for inputting/outputting signal of IC arranged at the middle point portion of the antenna by a technology of wire bonding or the like and at the same time, by connecting the circuit o

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