JP2003132314A - Non-contact type information storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constantly provide the best sensitivity without enlarging the dimension. SOLUTION: When information is written and read from an non-illustrated reader/writer, a voltage corresponding to each of multiple voltage values stored in an auxiliary memory 22 is provided to a varactor 13A as variable means, and after detecting the level of a signal obtained via a single antenna 12, the voltage to the varactor 13A is fixed to one corresponding to a maximum signal level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type information storage medium in which information is written and read by a non-contact type.

[0002]

[Prior art]

As a non-contact type information storage medium in which information is written and read by a non-contact type, there is one in the form of a label, a tag or a card.

For these non-contact type information storage media, when writing or reading information, a microwave method or an optical method is used.

FIG. 3 shows a microwave non-contact type label as an example of the non-contact type information storage medium. The non-contact type label 10 shown in the figure is provided with antennas 11 and 12 and capacitors 13 having different numbers of windings. These antennas 11 and 12 are contactless labels 1
When a metal piece or the like exists near 0, the antennas 11 and 12
The number is set to two in order to solve the problem that the sensitivity decreases due to the change of the tuning point due to the stray capacitance between the metal piece and the metal piece and the communication distance with the reader / writer (not shown) becomes short.

The microwaves received by either of the antennas 11 and 12 are rectified by the rectifier circuit 14 and then converted into electric power by the power supply regulator 15. In addition, the received microwave is the clock recovery circuit 1
When it is given to the demodulation circuit 17 via 6, it is demodulated by the demodulation circuit 17 and then written in the memory 19 via the communication logic circuit 18. On the other hand, when the information written in the memory 19 is read, the communication logic circuit 18 reads the information written in the memory 19 and after being modulated by the modulation circuit 20, It is transmitted from either antenna 11 or 12.

[0007]

As described above, in the conventional non-contact type label 10, in order to solve the above-mentioned inconvenience caused by the change of the tuning point, the number of windings is set to the capacitor 13 whose capacitance value is fixed. It is necessary to provide a plurality of antennas 11 and 12 of different types. However, the antenna 1
If multiple 1 and 12 are provided, the non-contact type label 1
There is a problem that the size of 0 itself becomes large.

The present invention has been made in view of such a situation, and it is possible to provide a non-contact type information storage medium which can always obtain the best sensitivity without increasing the size. To do so.

[0009]

A non-contact type information storage medium according to claim 1 is a non-contact type information storage medium in which information is written or read by a reader / writer, and a predetermined number of windings is performed. It has a single antenna, variable means for changing the level of the signal obtained through the antenna by varying the capacitance, and a plurality of voltage values for varying the capacitance are stored. When the writing or reading of information is performed with the auxiliary memory in which the level of the changing signal is written and the voltage corresponding to each of the plurality of voltage values is given to the variable means to detect the level of the signal,
And a control means for adjusting the voltage to the variable means according to the maximum signal level. Further, the control means may fix the voltage to the variable means after writing the level of the signal corresponding to the applied voltage value in the auxiliary memory. Also, the variable means may be a varactor. In the non-contact information storage medium according to the present invention, when information is written or read by the reader / writer, the control means changes the voltage corresponding to each of the plurality of voltage values stored in the auxiliary memory. The voltage to the variable means is fixed to the one corresponding to the maximum signal level after detecting the level of the signal obtained through the single antenna.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing an embodiment in which the non-contact type information storage medium of the present invention is applied to a non-contact type label, and FIG. 2 explains the operation of the non-contact type label of FIG. It is a flowchart for. In the drawings described below, the same parts as those in FIG. 3 are designated by the same reference numerals.

The contactless label 10A shown in FIG. 1 includes an antenna 12, a varactor 13A, a rectifier circuit 14, a power supply regulator 15, a clock recovery circuit 16, a demodulation circuit 17, a communication logic circuit 18, a memory 19, a modulation circuit 20, and a control circuit. The unit 21 and the auxiliary memory 22 are provided.

The antenna 12 is a single antenna having a predetermined number of turns. The varactor 13A is a variable capacitance diode whose capacitance can be changed according to the voltage supplied from the control unit 21.

The rectifying circuit 14 rectifies the microwaves taken in via the antenna 12. The power supply regulator 15 generates electric power from the rectified microwave.

The clock reproduction circuit 16 reproduces the clock contained in the microwave. Demodulation circuit 17
Is for demodulating the signal reproduced by the clock reproducing circuit 16.

The communication logic circuit 18 writes information demodulated by the demodulation circuit 17 in the memory 19. The memory 19 is composed of, for example, a ferroelectric non-volatile memory, and is capable of writing and reading information. The modulation circuit 20 modulates the information in the memory 19 read by the communication logic circuit 18.

When information is written or read by a reader / writer (not shown), the control unit 21 is based on a plurality of voltage values within the range of the lower limit value to the upper limit value stored in the auxiliary memory 22, and the varactor 13A. To the varactor 13A after the signal level of the input terminal a corresponding to each voltage is written in the auxiliary memory 22 while changing the voltage to
The voltage to is fixed to the one corresponding to the maximum signal level.

The auxiliary memory 22 stores a plurality of voltage values within a range from the lower limit value to the upper limit value given to the varactor 13A. In addition, the control unit 21 writes a signal level corresponding to a plurality of voltage values in the auxiliary memory 22.

Next, the non-contact type label 1 having such a structure.
The operation of 0A will be described.

First, when information is written or read by a reader / writer (not shown), power is generated by the power supply regulator 15 (steps 201, 20).
2). At this time, the control unit 21 sequentially reads the voltage values stored in the auxiliary memory 22 from the lower limit value, and the voltage of the read voltage value is read by the varactor 13A.
(Steps 203 and 204).

The capacitance of the varactor 13A changes according to the voltage supplied, and the input terminal a changes in accordance with the change of the capacitance.
The signal level of changes. This changing signal level is
The varactor 13A supplies the auxiliary memory 2 according to the supplied voltage.
2 is written (step 205).

When the voltage supplied to the varactor 13A reaches the voltage value of the upper limit value stored in the auxiliary memory 22 (step 206), the control unit 21 causes the signal level of the input terminal a corresponding to each voltage. Among them, the maximum signal level is detected (step 207), and based on the voltage value corresponding to the maximum signal level, it is fixed to the one corresponding to the maximum signal level to the varactor 13A (step 207). Step 208).

As a result, the varactor 13A is fixed to the capacity that provides the maximum sensitivity.

As described above, in this embodiment, when information is written or read by the reader / writer (not shown), the control unit 21 as the control means controls the plurality of voltage values stored in the auxiliary memory 22. A voltage corresponding to each of the above is applied to the varactor 13A as a variable means, the level of the signal obtained through the single antenna 12 is detected, and then the voltage to the varactor 13A corresponds to the maximum signal level. Since it is fixed to, the optimum sensitivity can always be obtained without increasing the size.

Further, since the sensitivity can be changed according to the voltage applied to the varactor 13A, even if the non-contact type label 10A is attached to the metal body or the metal fitting is attached to the non-contact type label 10A, there is no influence. Can be put to practical use without

In the present embodiment, the case where the control unit 21 reads the voltage values stored in the auxiliary memory 22 in order from the lower limit value has been described, but the present invention is not limited to this example, and the upper limit value is read in order. You may make it available.

Further, although the case where the non-contact type information storage medium of the present invention is applied to the non-contact type label 10A has been described in the present embodiment, the present invention is not limited to this example, and the non-contact type tag and the non-contact type. It may be applied to other non-contact type information storage media such as cards.

[0028]

As described above, according to the non-contact type information storage medium of the present invention, when information is written or read by the reader / writer, a plurality of voltages stored in the auxiliary memory are controlled by the control means. Apply the voltage corresponding to each value to the variable means, detect the level of the signal obtained through the single antenna, and then fix the voltage to the variable means to the one corresponding to the maximum signal level. Therefore, the best sensitivity can always be obtained without increasing the size.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment in which a non-contact type information storage medium of the present invention is applied to a non-contact type label.

FIG. 2 is a flow chart for explaining the operation of the non-contact type label of FIG.

FIG. 3 is a diagram for explaining a conventional non-contact type label.

[Explanation of symbols]

10A non-contact label 12 antennas 13A varactor 14 Rectifier circuit 15 Power supply regulator 16 clock recovery circuit 17 Demodulation circuit 18 Communication logic circuit 19 memory 20 Modulation circuit 21 Control unit 22 Auxiliary memory Input terminal

Claims (3)

[Claims] 1. A non-contact type information storage medium in which information is written and read by a reader / writer, wherein a single antenna having a predetermined number of turns and a level of a signal obtained through the antenna are provided. A variable unit for changing the capacitance by changing the capacitance; an auxiliary memory in which a plurality of voltage values for varying the capacitance are stored, and a level of the signal that changes according to the voltage value is written; When information is written or read, a voltage corresponding to each of the plurality of voltage values is applied to the variable means to detect the level of the signal, and then the voltage to the variable means becomes maximum. A non-contact type information storage medium, comprising: a control means adapted to the level of. 2. The control means fixes the voltage to the variable means after writing the level of the signal corresponding to the given voltage value in the auxiliary memory. The non-contact type information storage medium described. 3. The non-contact type information storage medium according to claim 1, wherein the variable means is a varactor.