JPH05197845A - Non-contact ic card device - Google Patents

Abstract

PURPOSE:To secure the normal communication regardless of the position of a moving object with respect to a non-contact IC card device which performs the radio communication between a non-contact IC card provided to the moving object and a ground station and identifies the moving object based on its information. CONSTITUTION:A ground station 1 is provided with the power dividers 2, 3 and 6 which perform the detection in the same phase as a receiver, the mixers 4 and 5, and a mixer which performs the detection separately from a system. Furthermore, a phase shifter 10 as well as a variable amplifier 9 which controls the phase and the amplitude of each detection output are added to the station 1 together with an adder 11 which adds together the detection outputs of two systems. In such a constitution, the amplitude and the phase of the detection signal of one of both systems are controlled by the amplifier 9 and the shifter 10 and two signals are added together by the adder 11 of the next stage. Thus it is possible to always demodulate the signal that is free from the influence of the phase change due to the position change of a moving object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contactless IC card device applied to an automatic collection system of a fee machine,
It can also be applied to mobile body identification systems such as line monitoring and entry / exit management.

[0002]

2. Description of the Related Art A conventional toll collection system employs a system in which a tollgate collector directly collects cash from a driver or an automatic machine automatically collects tolls. Therefore, the driver needs to stop at the toll booth and prepare cash. Therefore, as a future fee collection system, non-stop cashless systems using non-contact IC cards have been developed all over the world.

A charge collection system using a contactless IC card will be described with reference to FIG. As shown in the figure, a non-contact IC card 32 is attached inside the vehicle, for example, inside the windshield, and the IC card 32 stores information such as an ID number unique to each vehicle. There is.
On the other hand, a ground station 31 having an antenna 33 is arranged near the toll booth 35, and is connected to a terminal computer 34 in the toll booth 35.

In such a configuration, when a vehicle having the IC card 32 passes in front of the antenna 33, information such as an ID number and a toll is automatically wirelessly communicated between the antenna 33 and the IC card 32. It After the information is recognized by the ground station 31, it is transmitted to the terminal computer 34 and stored in the memory. Furthermore, the terminal computer 34
These pieces of information are transmitted from the host computer 36 to the host computer 36, and the passing fee is automatically settled from the bank account registered by the passing vehicle. Referring to FIG. 4, the ground station 31
The wireless communication between the card 32 and the card 32 will be described in detail. First, from the local oscillator 41 of the ground station 31 to the amplifier 4
Unmodulated wave (Continuo
us Wave) 61 is fired to the IC card 32.

The unmodulated wave 61 is received by the receiving antenna 49 arranged in the IC card 32, and the CPU 1
01 modulates this non-modulated wave with the information such as the ID number registered in the RAM 102 by the modulator 103, and transmits it as a modulated wave 62 from the transmitting antenna 100 to the ground station 31. The ground station 31 receives the modulated wave 62 with the receiving antenna 33b, performs homodyne detection with the mixer 45, and demodulates information such as the ID number of the card. This demodulated signal is
After removing the noise component with the band-hass filter 46, I
The F amplifier 47 amplifies the signal to an appropriate size and the comparator 4
The waveform is shaped in 8 and sent to the terminal computer 34 as a digital signal. As a result, from the IC card 32 to the ground station 3
The information in the IC card 32 can be transmitted to the IC card 1 without contact.

[0006]

As described above, according to the charge collection system using the non-contact IC card, a non-stop cashless charge collection system is realized and the convenience of the driver is significantly improved. In the above description, the postpaid method (postpaid method) is described, but if the IC card has a settlement function, the prepaid method (prepaid method) can be easily realized. However, in the above-mentioned conventional toll collection system, the ground station 31 demodulates the modulated wave by the homodyne detection method. Therefore, as shown in FIGS. There was a problem such as flipping.

That is, as shown in FIG.
Not only the modulated wave 62 from the card 32 but also the transmitted leaky wave 52 from the transmitting antenna 33a and the unnecessary reflected wave 51 from the vehicle body or the like are input to b. The transmitted leaky wave 62 and the unnecessary reflected wave 51 are generated by the mixer 4 depending on the distance between the ground station 31 and the vehicle.
Since the phases input to 5 are different, the output of the mixer 45 changes depending on the relationship with the phase of the local oscillator 41. That is, if the phase difference between the oscillator and the received wave is 0 °, the output of the mixer 45 is a positive output and the phase difference is 180 °.
If it is °, the output will be negative. Also, the phase difference is 90 °,
No output at 270 °. Therefore, as shown in FIG. 6, the unmodulated wave 61 is modulated by the data signal 20 including the information such as the ID number registered in the RAM 102 to become the modulated wave 62, but the output 63 of the mixer is used for moving the vehicle. It will be changed accordingly.

Therefore, the mixer output 63 passes through the bandpass filter 46 to become the output 64, and further passes through the comparator 48 to become the output 65. This comparator output 65 is in the normal phase which is in phase with the data signal 20. It is classified into a region, an inversion region having a reverse phase, and a non-reaction region where no output is obtained. The data signal 20 is normally demodulated in the normal region, but the incorrect data signal 20 is demodulated in the inversion region and the non-reactive region.

As described above, in the conventional homodyne detection, the normal communication area is limited as the vehicle moves,
It was difficult to secure stable communication. The present invention is
The present invention has been made in view of the above-mentioned conventional art, and an object thereof is to provide a contactless card device capable of ensuring normal communication regardless of the movement of a vehicle.

[0010]

The structure of the present invention for achieving such an object is a power divider and a mixer for performing in-phase detection on a receiver in a ground station of a contactless card system used for mobile identification. In addition to the above system, a mixer for performing detection is provided, a variable amplifier for controlling the phase and amplitude of each detection output and a phase shifter are provided, and an adder for adding the detection outputs of two systems is provided. And

[0011]

In the noncontact IC card device of the present invention, the signal detected in the same phase and the signal detected in the different path are affected by the phase change caused by the movement of the vehicle in the same manner. At this time, the amplitude and phase of the detection signal of one system are controlled by the variable amplifier and the phase shifter, and when the two signals are added by the adder in the subsequent stage, the influence of the phase change due to the position change of the moving body is eliminated. The signal will be demodulated normally.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 shows a ground station 1 according to an embodiment of the present invention. As shown in FIG. 1, the ground station 1 has a local oscillator 41, and this local oscillator 41 is connected to an amplifier and is connected to a transmitting antenna 13 via a power divider 2. Further, the ground station 1 has a transmitting antenna 13
In addition to this, there is a receiving antenna 14, and the receiving antenna 14 is connected to the two power dividers 3 and 6.

The power dividers 3 and 6 are provided with mixers 4 and 5, respectively. The mixer 5 is connected to a band-hass filter 8 and an adder 11 is arranged at the subsequent stage. On the other hand, the mixer 4 is connected to the adder 11 via the band-hass filter 7, the variable amplifier 9 and the phase shifter 10. The output of the adder 11 is connected to the comparator 12, waveform-shaped, and then sent to an external terminal computer 34. On the other hand, a mobile body (not shown) is provided with an IC card storing information such as an ID number unique to each vehicle, and the configuration thereof is the same as that shown in FIG.

In the ground station 1 of the present embodiment having the above-mentioned configuration, a non-modulated wave is emitted from the local oscillator 41 of the ground station 1 to the IC card (not shown) via the amplifier, the power divider 2 and the transmitting antenna 13. Then, the unmodulated wave is received by the receiving antenna arranged in the IC card, and the CPU modulates the unmodulated wave with the information such as the ID number registered in the RAM by the modulator, and the transmitting antenna It is transmitted as a modulated wave to the ground station 31.

The modulated wave from the IC card is received by the receiving antenna 1.
4 and is input to the mixer 5 via the power divider 3 and the power divider 6 in the same phase. Therefore,
Homodyne detection is performed in the mixer 5, and the output ω _{1 of the} mixer 5 is expressed by the following equation. This output ω ₁ is shown by the waveform 21 (only the lower sideband) in FIG. ω ₁ = [A ₁ cos {ωt + φ (x)} + A ₂ cos {ωt + φ ′ + φ (x)} + A ₃ cos {ωt + φ}] ² (1) where A ₁ : amplitude of the modulator of the IC card ( (Data information) φ (x): Phase difference between modulator and transmitted wave (changes with vehicle distance x) A ₂ : Amplitude of unwanted reflected wave from vehicle body φ ′: Phase difference between unwanted reflected wave and transmitted wave A ₃ : Transmission Amplitude of leakage wave φ: Phase difference between transmitted leakage wave and transmitted wave

This signal is supplied to the band-hass filter 8 in the subsequent stage.
Since the band is limited so as to pass only the main spectrum of the data information, the expression (1) is expressed by the following expression. This signal ω ₁ ′ is shown by the waveform 23 in FIG. ^{_{ω 1 '= A 1 2/}} 2 + A 1 A 3 cos {ωt + φ} + A 2 A 3 {ωt + φ' + φ (x)} On the other hand ... (2), the mixer 4, the output of the local oscillator 41 via the power divider 2 Since the received signal is input via a part of the above and the power divider 6, the homodyne detection is performed, and the output ω _{2 of the} mixer 4 is expressed by the following equation. This output ω ₂
Is indicated by waveform 22 (only the lower sideband) in FIG.

Ω ₂ = [A ₁ cos {ωt + φ (x)} + A ₂ cos {ωt + φ ′ + φ (x)} + A ₃ cos {ωt + φ}] × A ₄ cos (ωt + θ) (3) where A ₄ : Output of the power divider 2 θ: Phase difference between the output of the power divider 2 and the transmitted wave If the output ω _{2 of the} mixer 4 is band-limited by the band-hass filter 7 as in the case of the in-phase detection system, equation (3) becomes It is expressed by the following equation. This output ω ₂ ′ is shown by waveform 24 in FIG. ω ₂ ′ = (1/2) A ₁ A ₄ cos {φ (x) −θ} + (1/2) A ₂ A ₄ {φ (x) + φ′−θ} (4)

The above ω ₂ ′ is changed by the variable amplifier 9 in the subsequent stage to A ₄ =
The amplitude is adjusted so that it becomes 2 A _3, and the phase shifter 10
When the phase is adjusted so that θ = φ + π, the equation (2) is transformed into the following equation. The output ω ₂ ″ of the phase shifter 10 is shown by a waveform 25 in FIG.2. Ω ₂ ″ = −A ₁ A ₃ cos {φ (x) −φ} −A ₂ A ₃ {φ (x) + φ ′ -Φ} (5)

After adjusting the amplitude and phase in this way,
When ω ₁ ′ of the equation (2) and ω ₂ ″ of the equation (5) are added by the adder 11, the output ω ₀ of the adder 11 is represented by the following equation: ω ₀ = ω ₁ ′ + ω ₂ ″ = A ₁ ^2/2 ... (6) output omega ₀ of the thus adder 11, as shown by the waveform 26 in FIG. 2, it will be consistent with data information 20, further waveform shaping in a subsequent comparator 12 By making the waveform 27, the data signal from the IC card is normally demodulated.

[0020]

As described above in detail with reference to the embodiments, the present invention provides two series of homodyne detection, a variable amplifier for adjusting the amplitude of one series of output signals, and a phase shift for adjusting the phase. It is possible to eliminate the influence of the phase change based on the position of the vehicle by providing the adder and adding the outputs of the adders. Therefore, there is no inversion region or no response region in the demodulated signal based on the vehicle position,
Stable communication is possible, and communication reliability and system application flexibility are greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a ground station according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing a process of signal demodulation in one embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a fee collection system using a contactless IC card.

FIG. 4 is a block diagram showing an outline of a conventional ground station and a non-contact IC card.

FIG. 5 is an explanatory diagram showing radio wave propagation.

FIG. 6 is a waveform diagram showing a process of demodulating a signal in a conventional technique.

[Explanation of symbols]

 1 Ground station according to an embodiment of the present invention 2,3,6 Power divider 4,5 Mixer 7,8 Band lot filter 9 Variable amplifier 10 Phase shifter 11 Adder 12 Comparator 20 Data signal 21 Output waveform of mixer 5 22 Output waveform of mixer 4 23 Output waveform of bandpass filter 24 Output waveform of bandpass filter 7 Output waveform of phase shifter 10 26 Output waveform of adder 11 Output waveform of comparator 12 31 Conventional ground station 32 IC card 33 Antenna 34 Terminal Computer 35 Toll Gate 36 Host Computer 41 Local Oscillator 43 Amplifier 44 Power Divider 45 Mixer 46 Band Bus Filter 47 IF Amplifier 48 Comparator 49 Receive Antenna 51 Unwanted Reflected Wave 52 Transmit Leaked Wave 53 Mixer 45 Output Waveform 61 Unmodulated Wave 62 Modulated wave 64 Output waveform of band pass filter 45 65 Output waveform of comparator 48 100 Transmitting antenna 101 CPU 102 RAM 103 Modulator

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[Procedure amendment]

[Submission date] February 10, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

The unmodulated wave 61 is received by the receiving antenna 49 arranged in the IC card 32, and the CPU 1
01 modulates this non-modulated wave with the information such as the ID number registered in the RAM 102 by the modulator 103, and transmits it as a modulated wave 62 from the transmitting antenna 100 to the ground station 31. The ground station 31 receives the modulated wave 62 with the receiving antenna 33b, performs homodyne detection with the mixer 45, and demodulates information such as the ID number of the card. This demodulated signal is
After removing the noise component with the bandpass filter 46, I
The F amplifier 47 amplifies the signal to an appropriate size and the comparator 4
The waveform is shaped in 8 and sent to the terminal computer 34 as a digital signal. As a result, from the IC card 32 to the ground station 3
The information in the IC card 32 can be transmitted to the IC card 1 without contact.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

Each of the power dividers 3 and 6 is provided with mixers 4 and 5, and the mixer 5 has a bandpass filter.
It is connected to the filter 8 and the adder 11 is arranged at the subsequent stage. On the other hand, the mixer 4 is connected to the adder 11 via the bandpass filter 7, the variable amplifier 9 and the phase shifter 10. The output of the adder 11 is connected to the comparator 12, waveform-shaped, and then sent to an external terminal computer 34. On the other hand, a mobile body (not shown) is provided with an IC card storing information such as an ID number unique to each vehicle, and the configuration thereof is the same as that shown in FIG.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

This signal is supplied to the band pass filter 8 in the subsequent stage.
In the DC component (A ₂ × A ₃ terms, A ₁ ² term, A ₂ ² sections, A ₃ ²
2) and higher-order components (2ωt term) are removed, and the band is limited so as to pass only the main spectrum of the data information. Therefore, the equation (1) is expressed by the following equation. This signal ω ₁ ′
Is shown as waveform 23 in FIG. ω ₁ ′ = A ₁ A ₂ cos φ ′ + A ₁ A ₃ cos {φ (x) −φ} (2) On the other hand, in the mixer 4, a part of the output of the local oscillator 41 via the power divider 2, Since the received signal is input via the power divider 6, homodyne detection is performed, and the output ω _{2 of the} mixer 4 is expressed by the following equation. This output ω ₂
Is indicated by waveform 22 (only the lower sideband) in FIG.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Ω ₂ = [A ₁ cos {ωt + φ (x)} + A ₂ cos {ωt + φ ′ + φ (x)} + A ₃ cos {ωt + φ}] × A ₄ cos (ωt + θ) (3) where A ₄ : output of power divider 2 theta: similar to the system of the phase difference the phase detector output and the transmission wave of the power divider 2, van output omega ₂ of the mixer 4
The DC component (A ₂ × A ₄ term, A ₃ × A ₄
Data) and higher-order components (2ωt term) are removed, and data information
(3) is expressed by the following equation when the band is limited so as to pass only the main spectrum of . This output ω ₂ ′ is shown by waveform 24 in FIG. ω ₂ ′ = (1/2) A ₁ A ₄ cos {φ (x) −θ} (4)

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

The above ω ₂ ′ is changed by the variable amplifier 9 in the subsequent stage to A ₄ =
The amplitude is adjusted so that it becomes 2 A _3, and the phase shifter 10
When the phase is adjusted so that θ = φ + π, the equation (2) is transformed into the following equation. The output ω ₂ ″ of the phase shifter 10 is shown by the waveform 25 in FIG. 2. ω ₂ ″ = −A ₁ A ₃ cos {φ (x) −φ} (5)

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

After adjusting the amplitude and phase in this way,
When ω ₁ ′ in the equation (2) and ω ₂ ″ in the equation (5) are added by the adder 11, the output ω ₀ of the adder 11 is represented by the following equation: ω ₀ = ω ₁ ′ + ω ₂ ″ = A ₁ A ₂ cos φ ′ (6) Since A ₂ cos φ ′ is constant in the equation (6),
The equation is expressed as ω ₀ = kA ₁ . In this way, the output ω ₀ of the adder 11 coincides with the data information 20 as shown by the waveform 26 in FIG. 2, and further the waveform shaping is performed by the comparator 12 in the subsequent stage to obtain the waveform 27. , The data signal from the IC card is normally demodulated.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Description of Reference Signs] 1 Ground station according to an embodiment of the present invention 2, 3, 6 Power divider 4,5 Mixer 7, 8 Bandpass filter 9 Variable amplifier 10 Phase shifter 11 Adder 12 Comparator 20 Data signal 21 Mixer 5 output waveform 22 mixer 4 output waveform 23 bandpass filter 8 output waveform 24 bandpass filter 7 output waveform 25 phase shifter 10 output waveform 26 adder 11 output waveform 27 comparator 12 output waveform 31 conventional Ground station 32 IC card 33 Antenna 34 Terminal computer 35 Tollgate 36 Host computer 41 Local oscillator 43 Amplifier 44 Power divider 45 Mixer 46 Bandpass filter 47 IF amplifier 48 Comparator 49 Receive antenna 51 Unwanted reflected wave 52 Transmitted leaky wave 53 Mixer 45 Output wave 61 unmodulated wave 62 output waveform 100 transmission antenna 101 CPU 102 RAM 103 modulator output waveform 65 comparator 48 of the modulating wave 64 band-pass filter 45

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (1)

[Claims] 1. A non-contact IC card device for identifying a mobile unit in the previous period by performing wireless communication between a non-contact IC card provided in the mobile unit and the ground station to obtain information about the mobile unit in the previous period. The receiver is equipped with a power divider that performs in-phase detection, a mixer, and a mixer that performs detection separately from the above system, and a variable amplifier and phase shifter that control the phase and amplitude of each detection output. A non-contact type IC card device comprising an adder for adding detection outputs of two systems.