CN104899534B - A kind of Non-contact Media Reader - Google Patents
A kind of Non-contact Media Reader Download PDFInfo
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- CN104899534B CN104899534B CN201510280314.6A CN201510280314A CN104899534B CN 104899534 B CN104899534 B CN 104899534B CN 201510280314 A CN201510280314 A CN 201510280314A CN 104899534 B CN104899534 B CN 104899534B
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Abstract
The present invention relates to a kind of Non-contact Media Reader.Increase the LC antiresonant circuits of series connection between the receiving circuit of traditional Non-contact Media Reader and aerial coil, and set pre-set threshold value as small as possible, illustrate carrier frequency of the resonant frequency as close possible to Non-contact Media Reader chip of LC antiresonant circuits, when the resonant frequency of LC antiresonant circuits and the carrier frequency of Non-contact Media Reader chip closer to when, bigger inhibitory action can be produced to carrier signal, and then improve card signal and the signal intensity ratio of carrier signal, equivalent in the case where carrier signal is constant, card signal is amplified, in the case where not changing the Q values of aerial coil and Non-contact Media Reader chip internal reception gain, improve non-contact card reader antenna receiving sensitivity.
Description
Technical field
The present invention relates to a kind of Non-contact Media Reader.
Background technology
Non-contact Media Reader uses 13.56MHz frequency standards at present, for the technical field of near-field communication, be according to
ISO14443 international standards, and the EMV Contactless Specifications for payment that EMVco is formulated
Systems payment standards are designed.Non-contact card mainly replys data by loading modulation technique to card reader at present,
Card data signal amplitude very little.Therefore, the antenna of Non-contact Media Reader needs enough receiving sensitivities best to realize
Reception.
Presently mainly received and increased by the Q values or the chip internal of raising Non-contact Media Reader that improve reception antenna
Beneficial two ways lifts the receiving sensitivity of non-contact card reader antenna.But improve the Q values of reception antenna, it is meant that
Non-contact card reader antenna is easy to be influenceed by the close of card, easily produces blind area, uniformity is also relatively poor.Improve non-
The chip internal reception gain of contact card reader, chip receiving circuit can also put noise while enlarging card signal
Greatly, chip decoding error, card read failed are caused.
Non-contact radio frequency card reader disclosed in application number 200820158571.8 includes microcontroller, non-contact device
Card reader chip FM1702SL, amplifying circuit, one-level resonance circuit, two level resonance circuit, shaping circuit, MCU pass through SPI communication
The continuous outgoing carrier signal of Interface Controller non-contact device card reader chip FM1702SL, the chip the 6th pin TX2, by amplification electricity
Sequentially coupling is to being used to filter out higher hamonic wave and the one-level LC resonance circuits for amplifying signal resonance and two level LC is humorous after the amplification of road
Shaken circuit, and carrier signal amplification is made into have the outside surface launching radio magnetic wave of enough energy on antenna.
But when receiving radio magnetic wave, because carrier signal amplifies the card signal that can suppress to receive, so as to be greatly reduced
The sensitivity of card reader reception antenna.
The content of the invention
The technical problems to be solved by the invention are：A kind of Non-contact Media Reader is provided, card reader antenna is improved and receives
Sensitivity.
In order to solve the above-mentioned technical problem, the technical solution adopted by the present invention is：
A kind of Non-contact Media Reader, including Non-contact Media Reader chip, EMC wave filters, impedance matching circuit, antenna
Coil and receiving circuit, the Non-contact Media Reader chip are connected with EMC wave filters and receiving circuit respectively；The EMC filters
Ripple device is connected by impedance matching circuit with aerial coil；Also include LC antiresonant circuits；The aerial coil passes through series connection
LC antiresonant circuits are connected with receiving circuit；The resonant frequency of the LC antiresonant circuits and Non-contact Media Reader chip
The difference of carrier frequency be less than pre-set threshold value.
The beneficial effects of the present invention are：Increase between the receiving circuit of traditional Non-contact Media Reader and aerial coil
Add the LC antiresonant circuits of series connection, and set pre-set threshold value as small as possible, illustrate the resonant frequency of LC antiresonant circuits
As close possible to the carrier frequency of Non-contact Media Reader chip, when resonant frequency and the contactless reading of LC antiresonant circuits
The carrier frequency of card device chip closer to when, bigger inhibitory action can be produced to carrier signal, so improve card signal with
The signal intensity ratio of carrier signal, equivalent in the case where carrier signal is constant, card signal is amplified, so as to improve
Non-contact card reader antenna receiving sensitivity.
Brief description of the drawings
Fig. 1 is a kind of structural representation of Non-contact Media Reader of the specific embodiment of the invention；
Label declaration：
10th, Non-contact Media Reader chip；20th, EMC wave filters；30th, impedance matching circuit；40th, aerial coil；50、LC
Antiresonant circuit；60th, receiving circuit.
Embodiment
To describe the technology contents of the present invention, the objects and the effects in detail, below in conjunction with embodiment and coordinate attached
Figure is explained.
The design of most critical of the present invention is：Between the receiving circuit of traditional Non-contact Media Reader and aerial coil
Increase the LC antiresonant circuits of series connection, and the resonant frequency of the LC antiresonant circuits and Non-contact Media Reader chip
The difference of carrier frequency be less than pre-set threshold value, set pre-set threshold value as small as possible.
Explanation of technical terms of the present invention：
It refer to Fig. 1, a kind of Non-contact Media Reader provided by the invention, including Non-contact Media Reader chip 10, EMC
Wave filter 20, impedance matching circuit 30, aerial coil 40 and receiving circuit 60, the Non-contact Media Reader chip 10 respectively with
EMC wave filters 20 and receiving circuit 60 connect；The EMC wave filters 20 are connected by impedance matching circuit 30 and aerial coil 40
Connect；Also include LC antiresonant circuits 50；The aerial coil 40 passes through series LC antiresonant circuit 50 and receiving circuit 60
Connection；The difference of the resonant frequency of the LC antiresonant circuits and the carrier frequency of Non-contact Media Reader chip is less than default
Threshold values.
It was found from foregoing description, the beneficial effects of the present invention are：In the receiving circuit of traditional Non-contact Media Reader
Increase the LC antiresonant circuits of series connection between aerial coil, and set pre-set threshold value as small as possible, illustrate that LC parallel connections are humorous
Shake circuit resonant frequency as close possible to Non-contact Media Reader chip carrier frequency, when the resonance of LC antiresonant circuits
The carrier frequency of frequency and Non-contact Media Reader chip closer to when, bigger inhibitory action can be produced to carrier signal, is entered
And card signal and the signal intensity ratio of carrier signal are improved, equivalent in the case where carrier signal is constant, card signal is entered
Row amplification, so as to improve non-contact card reader antenna receiving sensitivity.
Further, the pre-set threshold value is 847KHz.
The antenna receiving sensitivity of usual existing Non-contact Media Reader is 3.5mV or so (3.5mV is authentication requesting).
But if antenna environment is bad, or antenna size is smaller, and receiving sensitivity can be deteriorated, according to circumstances, it is possible to which sensitivity can be
10mV or so (value is smaller, represents that sensitivity is higher).In this case, if adding LC resonance circuits, receiving sensitivity
It can improve a lot, it is easy to 3.5mV, even 1mV can be reached.
For in theory, LC resonant frequency ranges be 13.56MHz-847KHz between 13.56MHz+847KHz, it is optimal
It is worth for 13.56MHz.Sensitivity during optimal value can reach 1mV, even more small.(because of test equipment problem, below 1mV can not
Test.)
| Pre-set threshold value | Antenna receiving sensitivity | Pre-set threshold value | Antenna receiving sensitivity |
| 0.05MHz | 1.0mV | 0.45MHz | 3.0mV |
| 0.10MHz | 1.0mV | 0.50MHz | 3.1mV |
| 0.15MHz | 2.0mV | 0.55MHz | 3.1mV |
| 0.20MHz | 2.3mV | 0.60MHz | 3.3mV |
| 0.25MHz | 2.4mV | 0.65MHz | 3.3mV |
| 0.30MHz | 2.6mV | 0.70MHz | 3.3mV |
| 0.35MHz | 2.8mV | 0.75MHz | 3.5mV |
| 0.40MHz | 3.0mV | 0.80MHz | 3.5mV |
As seen from the above table, when usual antenna receiving sensitivity is 3.5mV, corresponding pre-set threshold value is 0.80MHz, in reality
In experimentation, the pre-set threshold value used is 0.847MHz.
Further, the carrier frequency of the Non-contact Media Reader chip is 13.56MHz, the LC parallel resonances electricity
The resonant frequency range on road is 13.56MHz-847KHz between 13.56MHz+847KHz.
Further, the subcarrier frequency of the Non-contact Media Reader chip is 847KHz；The contactless Card Reader
The card data rate of device chip is 106KHz.
Further, the optimal value of the resonant frequency of the LC antiresonant circuits is 13.56MHz.
During actual experiment, the optimal value of the resonant frequency of LC antiresonant circuits is 13.56MHz, now, antenna
Receiving sensitivity can reach 1mV.
Further, the Non-contact Media Reader chip includes modulation module and demodulation module；
The modulation module is connected with EMC wave filters；The modulation module, EMC is transmitted signals to for modulating and sending
Wave filter；
The demodulation module is connected with receiving circuit；The demodulation module, sent for receiving and demodulating receiving circuit
Reception signal.
Further, the transmission signal is differential square signals, and chip power output can be made to reach maximum.
Further, the receiving circuit includes division module, for obtaining carrier signal and card signal.
The embodiment of the present invention 1
The operation principle of traditional Non-contact Media Reader：
Traditional Non-contact Media Reader includes Non-contact Media Reader chip, EMC wave filters, impedance matching circuit, day
Line coil also has receiving circuit.Non-contact Media Reader chip is used for transmission signal and reception signal, complete signal modulation and
Demodulation.
During Non-contact Media Reader transmission signal, radio-frequency driven pin TX1, TX2 pin of Non-contact Media Reader chip
13.56MHz differential square signals are exported, are transmitted again by impedance matching circuit after EMC wave filters filter out higher hamonic wave
It is radiate to aerial coil.
During Non-contact Media Reader reception signal, receiving circuit partial pressure from aerial coil obtains carrier signal and card is believed
Number, receiving circuit is exported by RX pins and obtains card data to after Non-contact Media Reader chip progress inter-process, demodulation.
Non-contact Media Reader provided by the invention be on the basis of traditional Non-contact Media Reader receiving circuit with
One LC antiresonant circuit of series connection between aerial coil, its resonant frequency is about 13.56MHz.
The operation principle of Non-contact Media Reader provided by the invention is：
When LC antiresonant circuits are when by signal that frequency is 13.56MHz, its impedance is maximum；When slowly away from frequency
When rate is 13.56MHz signal, its impedance slowly diminishes.
Setting the Non-contact Media Reader chip operation, subcarrier frequency is in 13.56MHz carrier frequency
847KHz, therefore, the actually active frequency of card signal are 13.56MHz-847KHz and 13.56MHz+847KHz.
Increase LC antiresonant circuits after, LC antiresonant circuits to frequency be 13.56MHz carrier signal suppress compared with
Greatly, to card signal suppress it is relatively small, equivalent to add between card signal and carrier signal signal intensity ratio (such as：Adopt
With traditional Non-contact Media Reader, the amplitude of card signal and carrier signal is 1:1, using contactless reading provided by the invention
After card device, the amplitude of card signal and carrier signal is 3:1).When chip, which receives, has the carrier signal of identical frequency on pin, card
The amplitude of signal becomes big.Therefore, LC antiresonant circuits in Non-contact Media Reader provided by the invention equivalent to one
Amplifier, its multiplication factor is according to related to the Q values of LC antiresonant circuits.
In terms of Non-contact Media Reader sends data：Set LC antiresonant circuits resonant frequency be about
13.56MHz.In 13.56MHz, the impedance of LC antiresonant circuits is maximum, and is real impedance, to the Q of card reader antenna coil
Value, matching and resonant frequency do not influence substantially, therefore LC antiresonant circuits are to Non-contact Media Reader transmit power, transmission
Data waveform does not also influence substantially.
In terms of Non-contact Media Reader receives data：When receiving card data, card signal passes through LC antiresonant circuits, card
Signal enters Non-contact Media Reader chip afterwards by LC antiresonant circuits " amplification ", and Non-contact Media Reader chip is to receiving
Card signal be demodulated processing, obtain card data.
In whole work process, it is not necessary to change the Q values of aerial coil, it is not required that change Non-contact Media Reader core
Piece internal receipt gain, only rely on LC antiresonant circuit cans and substantially increase card reader receiving sensitivity.
In summary, a kind of Non-contact Media Reader provided by the invention, in the reception of traditional Non-contact Media Reader
Increase the LC antiresonant circuits of series connection between circuit and aerial coil, and set pre-set threshold value as small as possible, illustrate LC simultaneously
Join carrier frequency of the resonant frequency as close possible to Non-contact Media Reader chip of resonance circuit, when LC antiresonant circuits
The carrier frequency of resonant frequency and Non-contact Media Reader chip closer to when, bigger suppression can be produced to carrier signal and is made
With, and then card signal and the signal intensity ratio of carrier signal are improved, equivalent in the case where carrier signal is constant, card is believed
Number it is amplified, in the case where not changing the Q values of aerial coil and Non-contact Media Reader chip internal reception gain, improves
Non-contact card reader antenna receiving sensitivity.
Embodiments of the invention are the foregoing is only, are not intended to limit the scope of the invention, it is every to utilize this hair
The equivalents that bright specification and accompanying drawing content are made, or the technical field of correlation is directly or indirectly used in, similarly include
In the scope of patent protection of the present invention.
Claims (8)
1. a kind of Non-contact Media Reader, including Non-contact Media Reader chip, EMC wave filters, impedance matching circuit, antenna line
Circle and receiving circuit, the Non-contact Media Reader chip are connected with EMC wave filters and receiving circuit respectively；The EMC filtering
Device is connected by impedance matching circuit with aerial coil；Characterized in that, also include LC antiresonant circuits；The aerial coil
It is connected by series LC antiresonant circuit with receiving circuit；The resonant frequency of the LC antiresonant circuits and contactless reading
The difference of the carrier frequency of card device chip is less than pre-set threshold value.
2. a kind of Non-contact Media Reader according to claim 1, it is characterised in that the pre-set threshold value is 847KHz.
A kind of 3. Non-contact Media Reader according to claim 1, it is characterised in that the Non-contact Media Reader chip
Carrier frequency be 13.56MHz, the resonant frequency ranges of the LC antiresonant circuits for 13.56MHz-847KHz extremely
Between 13.56MHz+847KHz.
A kind of 4. Non-contact Media Reader according to claim 3, it is characterised in that the Non-contact Media Reader chip
Subcarrier frequency be 847KHz.
A kind of 5. Non-contact Media Reader according to claim 3, it is characterised in that the LC antiresonant circuits it is humorous
The optimal value of vibration frequency is 13.56MHz.
A kind of 6. Non-contact Media Reader according to claim 1, it is characterised in that the Non-contact Media Reader chip
Including modulation module and demodulation module；
The modulation module is connected with EMC wave filters；The modulation module, EMC filtering is transmitted signals to for modulating and sending
Device；
The demodulation module is connected with receiving circuit；The demodulation module, for receiving and demodulating, receiving circuit sends connects
The collection of letters number.
7. a kind of Non-contact Media Reader according to claim 6, it is characterised in that the transmission signal is differential square
Signal.
8. a kind of Non-contact Media Reader according to claim 1, it is characterised in that the receiving circuit includes partial pressure mould
Block, for obtaining carrier signal and card signal.
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| CN201510280314.6A CN104899534B (en) | 2015-05-28 | 2015-05-28 | A kind of Non-contact Media Reader |
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| CN201510280314.6A CN104899534B (en) | 2015-05-28 | 2015-05-28 | A kind of Non-contact Media Reader |
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| CN104899534B true CN104899534B (en) | 2017-12-08 |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105225317A (en) * | 2015-10-03 | 2016-01-06 | 上海大学 | A kind of network access control system of multichannel centralized management |
| CN110598498B (en) * | 2019-09-12 | 2022-10-25 | 北京维普无限智能技术有限公司 | Method for improving signal identification capability of non-contact card reader |
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