CN1425210A - Antenna for contact-free transmission/reception reading system - Google Patents

Abstract

The invention concerns a reader antenna in a system of identification or of access to a zone with controlled access comprising a reader designed to detect responding electromagnetic signals coming from a contact-free portable object such as an ISO card or a disposable ticket (46), the responding magnetic signals being transmitted by an antenna (48) located in the portable object in reply to the reception of electromagnetic signals transmitted by the reader antenna when the bearer of the portable object presents the portable object in front of the reader. The antenna comprises n groups of turns (20, 22, 24) arranged in series wherein each group of k-1 turns includes a number of Nk-1 turns less than the number of Nk turns of the group of k turns (k ranging between 2 and n) and is spaced apart from the group of k turns by a distance Dk-1 greater than a predetermined value, the turns of all the groups being wound in the same direction.

Description

Antenna for contact-free transmission/reception reading system

Technical field

The present invention relates to use the transceiver system of reader, wherein this reader is designed to respond the electromagnetic signal of being launched by an antenna that is positioned at this reader and detects the not electromagnetic signal of contact emission of the portable type of being showed in the place ahead of this reader by its holder, and the invention particularly relates to the reader antenna of a kind of contact-free transmission/reception system.

Background technology

Be used to identify their holder or be used to enter the controlled district that enters, public transport links (such as the RATP MTR network or the SNCF MTR network of France) for example, portable object day by day with its with standard contact body (card or ticket) different being called " not contact " technology be feature.

Not the information exchange between contact and the reader normally by leave in this not long-range electromagnetic coupled between first antenna in the contact and second antenna in this reader realize.In addition, this object is being equipped an electronic building brick, it is characterized in that this first antenna is connected with solid-state pellet parts or chip, the latter is contained the various logic functions element that a radio frequency (RF) parts, storage will offer the information that the memory of information of this reader and information that compiling will send and processing receive except that other element.

Entering in the scene in district, in fact there are two class users: fixed-line subscriber and accidental user such as controlled in the public transport links.For first kind user, it is best solution that the ISO form does not contact smart card, because it distributes the cost price of card by the travel total degree on long time phase, thereby user's price is always kept low.But for the second class user who is made up of accidental user, because they need buy a card for single stroke, it is too high that the cost price of this card becomes with respect to the cost of a travel.

Also have the portable type ticket of the theme that constitutes No. 9908802 patent applications of France in the ISO format card, these ticket are littler than ISO card, and can disposablely use, and the ISO format card is not disposable use.Certainly, their less specifications have reduced the surface area of antenna on the ticket, and this requires these ticket to have the operating energy bigger than ISO format card.

Because of needing both to move together with disposable ticket again with the ISO format card in reader, when the front that is placed on it contact is not disposable ticket the time, must be enough greatly by the energy that described reader provides.Can be sufficient by traditional reader antenna of forming of number circles for the not contact of ISO format card size, but is insufficient for the not contact of ticket size.

A kind of solution of this problem can comprise by adding a minor loop that comprises several circles to introduce high field in this antenna, wherein is designed to as far as possible the highland and improves the normal component in the magnetic field of launching in the section of this minor loop.Muddled regret be that under disposable ticket situation, man-machine control confusion can appear in this antenna, because it is only correctly worked in the section of this minor loop.In addition, the field of setting up with these circles of this antenna on the normal component phase place in the magnetic field that this minor loop is set up in reader is opposite, and when the ISO format card faced toward this minor loop, this can cause tangible operation invalid.

In addition, for example at EP0,776,200 patents or US4, reader illustrated in the prior art of 922,261 patents is not handled this problem; Alternatively these readers are handled the transmitting antenna of readers and the problem that the coupling between the reception antenna causes, thus promptly on two circle groups are twined by be provided with opposite direction in two antennas one to set up phase place to make the mutual inductance with another antenna on the contrary be zero.Regrettably, this way can not address the above problem, because the magnetic field that produces in the reader is uneven fully.

Summary of the invention

Here it is why main purpose of the present invention provide a kind of being used for ISO format card or disposable ticket be used as not contacting identification or entering the reader antenna of system of portable object.

Another object of the present invention is not contact identification or entering a kind of reader antenna is provided in the system, and wherein this system provides magnetic field so uniformly on the whole surface of this reader.

Thereby purposes of the present invention is a kind of entering controlledly to enter the identification in district or enters reader antenna in the system, this enters system and comprises that one is designed to detect from such as the portable type of ISO type card or the disposable ticket reader of the electromagnetic response signal of contact not, wherein when the holder of this portable object showed this portable object in the front of this reader, an antenna response that is positioned at this portable object received the electromagnetic signal emission electromagnetic response signal of this reader antenna emission.This antenna comprises the circle group of n series connection, and wherein each circle group k-1 has one less than the number of turn N among the circle group k _kNumber of turn N _K-1, k changes to n from 2, and circle group k-1 is D greater than certain predetermined value from the distance of circle group k _K-1, all circles in each group are pressed equidirectional and are twined.

Description of drawings

Be inconjunction with the description of the drawings from below, purposes of the present invention, purpose and feature become clearer, and accompanying drawing is:

Fig. 1 represents counting traditional reader antenna that circle is a feature graphicly, and has the indication to the value of the magnetic field normal component at the diverse location place of this antenna.In the remainder of this paper, word " magnetic field " refers to the magnetic-field component perpendicular to antenna plane,

Fig. 2 represents the foundation reader antenna that is made of two circle groups of the present invention,

Fig. 3 represents the position according to the vertical line thigh with three circle groups these circles that are feature of the present invention,

Fig. 4 is a curve, represents that the distance of any endless metal wire from the electric current that wherein circulating is the magnetic field value at the some place of x,

Fig. 5 A, 5B and 5C are curves, represent respectively by the magnetic field of outer circle group generation, by the magnetic field of interior circle group generation and synthetic magnetic field,

Fig. 6 represents the magnetic field by the reader antenna generation with the peripheral circle of single group,

Fig. 7 represents the magnetic field by the reader antenna generation with several circle groups that satisfy condition of the present invention,

Fig. 8 represents the magnetic field by the reader antenna generation of the circle group of the condition with several discontented unabridged version inventions.

Embodiment

As shown in fig. 1, generate one with a plurality of circles 12,14,16 traditional antenna 10 that is feature and be positioned at the magnetic field that where changes with it.In such a way, this is worth for just in the section in these circles, and bears in the field, outside of these circles.If the mid point between two circles and be (because its with the reverse decline of distance but weak) of ignoring by the magnetic field that each circles of other parts causes, because the identical negative fluxfield of absolute value that the positive flux field that circle line thigh causes and another circle line thigh cause, combination field are zero.

On the electromagnetic signal that generates by this antenna emission, fixed-field is not a subject matter.The surface of showing the reader of portable object in its front is generally square (or rectangle), and each limit is 15cm to 20cm.If this antenna too is positioned at this surperficial center, exist a magnetic field to be negative section outside at these circles.Yet, if each circle of this antenna is positioned at the periphery on this reader surface, although reduce magnetic field from meeting far away more of these circles and distance inversely biglyyer, there be a blind area in (in the antenna) magnetic field in this surperficial center for just on the whole surface of this reader.If portable object is showed in the front in this blind area, this portable object can not receive enough energy.In addition, be inapplicable by increasing the circle line significantly so that add the solution that high-intensity magnetic field constitutes.Also can increase simultaneously the quantity that magnetic field wherein is zero section because increase surface area that these circles occupy.

Thereby the solution that the present invention proposes is by using such antenna to constitute, this antenna is made up of the circle group of n series connection, each circle group k (wherein k changes to n-1 from 1) is included in the group k+1, and the termination of the outer circle of group among the k and the termination of organizing the interior circle among the k+1 are connected.The number of turn among the group k is less than the number of turn among the group k+1.At last, by identical direction, for example, twine each circle in all circle groups from organizing 1 widdershins to group n.

Embodiment example under two group forms shown in Fig. 2, wherein the first circle group 20 comprise two rectangular turn and second group 22 comprise that 4 distances from first group are the rectangular turn of D.

If we studies show that Fig. 3 of the left vertical line thigh of three circle groups 40,42,44 in succession, 40 the left side is promptly organized in its outside in the magnetic field that circle group 40 generates, and bears.But occurring can be in these circle and especially in group 40 with organize in the space between 42 and generate positive flux field around the circle group 42 of circle group 40.

In general, the magnetic field of being responded to by the wide metal wire of the lm of the electric current I that wherein circulating has the value by the curve representation shown in Fig. 4.In the centre magnetic field of this lead is zero.If the initial point of abscissa is positioned at the centre of this line, magnetic field increases sharply then and reaches a geostationary value by following formula: ${\mathrm{<figure-callout\; id="1"\; label="H"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">H</figure-callout>}}_1={\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">K</figure-callout>}}_{1.}\frac{I}{2{\mathrm{\&pi;l}}_m}$ For 0＜x≤l _m

Then, reduce by the value of following formula as the inverse function H of abscissa: ${\mathrm{<figure-callout\; id="2"\; label="H"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">H</figure-callout>}}_2={\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">K</figure-callout>}}_{2.}\frac{I}{2\mathrm{\&pi;x}}$ For x＞l _m

Thereby the value in the magnetic field that is produced by the group of N circle is:

H=0 is for x=0

${H=K}_{1.}\frac{\mathrm{<figure-callout\; id="2"\; label="NI"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">NI</figure-callout>}}{{2\mathrm{\&pi;l}}_m}$ For 0＜x≤l _m

${H=\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\frac{\mathrm{<figure-callout\; id="2"\; label="NI"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">NI</figure-callout>}}{2\mathrm{\&pi;x}}$ For x＞l _m

Get back to Fig. 3, the value in each circle group 40 or 42 magnetic fields that generate in the space that is separated by this group can be respectively with the curve shown in Fig. 5 A and the 5B, and wherein the initial point of abscissa is got the mid point that becomes to be positioned at circle group 42.Please note the field (H that (Fig. 5 A) produces in the circle group 42 ₁) be positive, and the field (H that the outside of circle group 40 (Fig. 5 B) produces ₂) bear.

Synthetic value (H in the space between the group 40 and 42 _R) then be the algebraical sum of the field shown in Fig. 5 A and the 5B.In this value shown in Fig. 5 C then be:

H _R＝H ₁-H ₂

As can be seen, this value of synthetic was positive before this, then from the distance D from circle group 42 ' ₁Begin to bear.If D1 and D ' ₁(from D ' ₁Begin synthetic for negative) between difference very not obviously and the minimum dimension of the antenna on the disposable ticket, then be unimportant, because the mean value of the field that this ticket receives is just remaining and is inevitable greater than the required minimum value of assurance ticket work.But, might be by separating the distance D of two circle groups ₁Be chosen to equal D ' ₁So that this section is reduced to 0, be to be positive field entirely thereby provide in the space between two circle groups.In order to reach this point, negative field-H ₂Maximum value must be less than or equal to positive field+H ₁Least absolute value; This is approximately ${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">K</figure-callout>}}_{1.}=\frac{N_1\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">I</figure-callout>}}{{2\mathrm{\&pi;<figure-callout\; id="1"\; label="l\; m"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">l</figure-callout>}}_m}\&le;K_2\frac{N_2\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">I</figure-callout>}}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">D</figure-callout>}}_1}$

Perhaps

K _1.N _1.D _1.≤K _2.N _2.l _m1

As initially approaching, if allow two COEFFICIENT K ₁And K ₂Equate, can obtain:

N _1.D ₁≤ N _2.l _M1Lm ₁Must be less than D ₁, can find out by to N ₁And N ₂Select suitable value so that: $\frac{N_2}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}\&GreaterEqual;\frac{D_1}{{\mathrm{<figure-callout\; id="1"\; label="l\; m"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">l</figure-callout>}}_m}$ Perhaps, more generally, two in succession circle group k and k-1 between (wherein k changes to n from 2) make: $\frac{\mathrm{Nk}}{\mathrm{Nk}-1}\&GreaterEqual;\frac{\mathrm{Dk}-1}{l_m(k-1)}$ Can make this inequality for true.

Should note in these circles adding on positive that generates by circle group 40 by the positive field that circle group 42 generates, although since during away from circle group 42 the field value that increases that dies down diminish.Similarly, circle group 44 is around circle group 42.The negative fluxfield (and negative fluxfield of circle group 40 generations) that the positive flux field compensation circle group 42 that circle group 44 generates within these circles in the section between these two circle groups generates, this can allow to set up positive flux field or set up positive mean field at least in this section if there are enough circles.Please note at the positive flux field that circle group within the circle group 42 44 generates and add on positive that circle group 42 generates and adding within the circle group 40 on positive that circle group 40 generates, die down gradually but strengthen gradually with distance.

N the ever-increasing circle group of the number of turn can recursively be set so that cover the entire antenna surface of reader on antenna support.But have the parameter of the quantity n of circle group in the definition antenna: it is the distance between the circle group, i.e. D between first group and second group ₁, the D between second group and the 3rd group ₂, and and the like, be the D between group n-1 and the n at last _N-1Distance D ₁(between the group 40 and 42) or D ₂(between the group 42 and 44) must be best.Magnetic field accumulation around the mid point of mentioning with reference to Fig. 1 for fear of the front, it must not be too little.But this distance must not be too big, thus so that the enough high negative fluxfield that compensates previous circle group in the foundation of the outside of its circle of positive flux field.

Exist a decision simultaneously according to the decision parameter of the structure of antenna of the present invention.In fact disposable ticket must reader have a few and especially when it is positioned on certain the circle group that is generated as zero field, receive positive mean field.Thereby the minimum edge of ticket antenna must be greater than the width of each the circle group shown in Fig. 3, and the width of the antenna on the ticket 46 48 must be greater than the overall width of the wideest circle group 44.Owing to increase its number of turn more near each circle group of the periphery of this antenna, thus must reduce when forcing from a circle group to another bigger circle group circle metal width in case the width of this circle group always less than the minimum dimension of the antenna on the ticket.Thereby, except the following inequality that is applied to the example shown in Fig. 2: $\frac{N_2}{{\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="A0180834400132.png"\; state="\{\{state\}\}">N</figure-callout>}}_1}\&GreaterEqual;\frac{D_1}{l_{m1}}$ $\frac{N_3}{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">N</figure-callout>}}_2}\&GreaterEqual;\frac{D_2}{{\mathrm{<figure-callout\; id="2"\; label="l\; m"\; filenames="A0180834400152.png,A0180834400161.png"\; state="\{\{state\}\}">l</figure-callout>}}_m}$ Also must make following inequality for true:

l _m1＞l _m2＞l _m3

When observing above mentioned each inequality always, very clear, increase the number of turn of an outer circle group more, for example N ₃, can also increase the distance that this circle group is left its nearest interior circle group, for example D biglyyer ₂

That should note dividing in each circle group the next but two circle should be as much as possible little apart from d, is circle processing and goes up the minimum range of permitting.More generally, apart from d on amplitude less than distance D.In other words, distance D and must be greater than predetermined preferred value apart from the ratio between the d.The result is if the turn-to-turn width has set-point d, to mean that then distance D must be greater than certain predetermined value.

Because circle group in succession described above can obtain to be used to sufficiently high field card and that be used for disposable ticket for reader.In addition, this structure also allows to obtain field relatively uniformly on the whole surface of reader, and this does not exceed can be applied to the not predetermined field value of the standard of contact.This is made demonstration by following at three examples shown in Fig. 5,6 and 7, wherein the initial point of abscissa is positioned at the center of reader, and makes following imagination:

-disposable ticket be characterized as the square antenna that is of a size of 2cm * 2cm,

-reader is of a size of 20cm * 20cm,

-for the field minimum of card generation is 0.8A/m,

-the field minimum that is used for disposable ticket is 2A/m,

-field the value that needn't exceed is 7.5A/m,

Electric current in-each circle is 50mA.

1. under first situation shown in Figure 6, the feature of reader is a simple antenna, and this antenna is made of 4 concentric turns on this reader periphery, and the metal width of circle is that 1mm and turn-to-turn distance are 1mm.Notice that maximum field is the 15A/m at periphery place, thereby it is greater than the threshold value that allows.But near the field this reader center only is 0.8A/m, thereby it is not enough height for disposable ticket reader only for the enough height of card reader.

2. under second situation shown in Figure 7, constitute by three circle groups according to the antenna of reader of the present invention:

-being of a size of first group of 2 circles of 6cm * 6cm, metal width is that 0.3cm and turn-to-turn width are 0.1mm,

--be of a size of second group of 4 circles of 17cm * 17cm, wherein metal width is that 0.3cm and turn-to-turn width are 0.1mm,

-be of a size of the 3rd group of 6 circles of 20cm * 20cm, wherein metal width is that 1mm and turn-to-turn width are 0.1mm,

Can notice that field minimum is 2A/m, thereby be sufficiently high, and maximum field is 7.5A/m that it equals threshold limit for reading disposable ticket or card.

3. under the 3rd situation shown in Figure 8, the antenna of reader is similar to the antenna in second situation, but except the 3rd circle group, the metal width of the 3rd circle group equals 0.3cm rather than 1mm.

Can notice that the midfield, space between the second circle group and the 3rd circle group becomes to negative; This is not cause owing to reduce metal width in the 3rd circle group that has more circle than the second circle group.

Claims (7)

1. one kind is used for the controlled antenna that enters the identification in district or enter system, this system comprises that one is designed to detect from the reader such as the electromagnetic response signal that does not contact portable object of ISO type card or disposable ticket, wherein when the holder of this portable object shows described portable object in the front of described reader, an antenna response that is positioned at this portable object receives described electromagnetic signal of reading the body antenna emission, launches described electromagnetic response signal;

Described antenna features is its circle group that comprises n arranged in series (20,22,24), wherein the number of turn N that has of each circle group k-1 _K-1Less than the number of turn N among the circle group k _k, k changes to n from 2, and circle group k-1 is D greater than certain predetermined value from the distance of circle group k _K-1, by equidirectional twine all the group in each circle.

2. according to the reader antenna of claim 1, wherein the described quantity n of circle group is corresponding to enough circle group quantity, thereby this antenna covers the whole surface that the described reader of described portable object is showed in its front.

3. according to claim 2 reader antenna, it is characterized in that three circle groups (40,42,44).

4. according to claim 1,2 or 3 reader antenna, all contour dimensions of antenna that wherein are positioned at described portable object are greater than the width of the circle that constitutes any described circle group.

5. according to the reader antenna of arbitrary claim in the claim 1 to 4, wherein two circle group k-1 and k in succession, k change to n from 2, between following inequality be true: $\frac{\mathrm{Nk}}{\mathrm{Nk}-1}\&GreaterEqual;\frac{\mathrm{Dk}-1}{l_m(k-1)}$ Lm in the formula (k-1) is the width that constitutes the metal wire of circle group k-1.

6. according to the reader antenna of arbitrary claim in the claim 1 to 5, wherein for the k value ratio D of any scope from 2 to n _K-1/ d is greater than a predetermined value, and d is the value of predesignating of two distances between the adjacent turn.

7. according to the reader antenna of above-mentioned arbitrary claim, wherein said reader is of a size of 20cm * 20cm and described disposable ticket comprises an antenna (48) that is of a size of 2cm * 2cm.

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