Contacless identifying media
A non-contact identification and media technology, which is applied to the recording carrier, printing, and loop antenna used by the machine, can solve the problems of reducing the Q value of the antenna resonant circuit, insufficient receiving voltage, and increasing the possible distance of communication, etc., so as to increase the communication distance. Distance, the effect of increasing the Q value
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no. 1 approach
[0042] Embodiments of the present invention will be described below with reference to the drawings.
[0043] FIG. 3 shows a circuit configuration applicable to a non-contact IC card as an example of implementation of the present invention. For example, the carrier frequency is 13.56 MHz. The number of turns of the antenna coil 1 is 10 turns, and a center tap is set at the position of 3 turns. At its center tap a capacitor 5 connected in series to the integrated circuit chip 3 .
[0044] Since the inter-terminal capacitance 3A of the integrated circuit chip is connected in series with the capacitor 5, the equivalent capacitance seen from the side of the coil is:
[0045] Cs / (1+Cs / Cin)...(Formula 1)
[0046] Here, Cin is the inter-terminal capacitance 3A, and Cs is the capacitance of the capacitor 5 connected in series.
[0047] It can be seen from the formula 1 of the equivalent capacitance that the present invention contributes less to the resonance frequency of Cin than w...
no. 2 approach
[0050]FIG. 4 shows the addition of a capacitor 6 connected in parallel with the integrated circuit chip in the configuration of the first embodiment. In this way, if the capacitance 3A between terminals of the integrated circuit chip is smaller than that of the capacitor 5 in series, the capacitance of the capacitor 6 can be made greater than the capacitance of the capacitor 5, so the pair resonance caused by the manufacturing difference of the integrated circuit chip 3 can be surely reduced. The influence of the frequency can also reduce the entire resonant capacitance and increase the inductance of the coil, so the induced power can also be increased.
[0051] Also in the configuration of FIG. 4 , by making the capacitance of the second capacitor 5 smaller than the sum of the capacitance 3A of the integrated circuit chip and the capacitance of the third capacitor 6 , the same effect as that of the above-mentioned first embodiment can be obtained.
no. 3 approach
[0053] In FIG. 5, as another implementation example of the present invention, a circuit configuration in the case of applying to a non-contact IC card is shown. For example, the carrier frequency is 13.56 MHz. As shown in FIG. 5 , an antenna coil 1 , a capacitor 7 and an integrated circuit chip 3 are provided, and the integrated circuit chip 3 and the antenna coil 1 are connected in series through the capacitor 7 .
[0054] The equivalent capacitance seen from the coil is:
[0055] C1 / (1+C1 / Cin)...(Formula 2)
[0056] Here, the capacitance C1 of the capacitor 7 is made smaller than the inter-terminal capacitance Cin3A of the integrated circuit chip.
[0057] In this way, the inductance of the antenna coil 1 and the capacitance C1 of the first capacitor 7 play a decisive role on the resonant frequency, and the influence on the resonant frequency caused by the manufacturing difference of the inter-terminal capacitance 3A of the integrated circuit chip 3 is greatly reduced, Th...
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