CN101276427A

CN101276427A - RFID label with improved scope

Info

Publication number: CN101276427A
Application number: CNA2007100936539A
Authority: CN
Inventors: 朱生勃; 黄世雄
Original assignee: MAGETIC Corp
Current assignee: MAGETIC Corp
Priority date: 2007-03-30
Filing date: 2007-03-30
Publication date: 2008-10-01

Abstract

An RFID label including an rfid integrated circuit and an antenna is combined with a first passive antenna circuit to provide the expanded work range. The first passive antenna circuit includes a first multi-cycle coil and a first capacitor and is used for tuning the passive antenna circuit to a resonance frequency which is fundamentally identical to the working frequency of the RFID label. The first coil includes a central opening whose size is larger than that of the antenna. The passive antenna circuit is arrayed to enable the antenna to preferably locate within the central opening of the coil in a coplanar manner, thus promoting the inductive interaction between the antenna and the coil. A second passive antenna circuit, which is basically same as the first passive antenna circuit but has larger size, is positioned to lead the coil of the second passive antenna circuit to surround the first coil, therefore further expanding the work range.

Description

The RFID label that has improvement threshold

Technical field

The present invention relates to rfid (radio-frequency (RF) identification) chip and antenna technical field.The invention particularly relates to the rfid chip and the antenna that use the r.f. inquiry/fetch equipment that is associated and have improved communication range.

Background technology

Shown in the United States Patent (USP) of on November 28th, 2000 issue the 6th, 154, No. 137 (it openly is incorporated herein by reference) and as described in, typical rfid chip and antenna are combined in the ID label usually simultaneously.The ID label has usually and is installed on the thin substrate or is sealed in antenna and rfid chip in the thin substrate, the United States Patent (USP) the 6th of issue in above-mentioned thin substrate such as on April 16th, 2002, disclosed polyethylene terephthalate (PET) substrate 25 in 373,708 B1 numbers (it openly is incorporated herein by reference).Antenna is miniature toroidal antenna or dipole antenna normally, and must be connected with rfid chip ohm.Common tours antenna is to use the multiturn plane ohmic conductor of any formation in some known methods.A kind of such technology is the silver slurry printing on suitable substrate (such as above-mentioned PET substrate).The another kind of known method that is used to form tours antenna is by copper sedimentation on the substrate of the RCD Technology Corporation practice in Pennsylvania Bethlehem city.The size of coil (coil diameter and thickness) and the number of turn are by comprising that ID label physical size is constrained in interior application-specific to be required to determine.The function of antenna provide rfid chip and external challenges/fetch equipment (such as, host CPU, user read station etc.) between the electromagnetic transfer of information; And allow electric power inducted from external unit and be passed to the rfid chip so that provide electric power for the active circuit element in the rfid chip.

Existing known multiple commercial rfid chip, they have the common standard internal functional unit that can find separately in the rfid integrated circuit.These standardized components comprise RF and simulation part, CPU, ROM and EEPROM (referring to 1999 IEEE International Solid-State Circuits Conference publicaton0-7803-5129-0/99, Fig. 9 .1.1:RFID transponder IC block diagram).The Rfid chip receives electric power via antenna when being inquired by external unit, and the use standard agreement (such as, ISO 14443 agreements or ISO 15693 agreements) and this external device communication.Before a target was installed the ID label, the information of discerning target to be attached was written among the ROM (ROM (read-only memory)) that is combined in the rfid chip.In case this information is by write-once ROM, it just can't be by any inquiry unit overwrite and change.This rfid chip can and just provide this information to external unit by external challenges/fetch equipment inquiry, and promptly it can't change the information that is stored in the ROM.

The ID label of above-mentioned type with rfid chip and antenna is very useful for target following, and uses in various this class is used at present.Be applied in of this technology is feasible in theory, but its actual be implemented in over be restricted because of the constraint of size and cost.These constrain in recently and are solved by improved semiconductor batch treatment technology, wherein use this technology to generate minimum rfid chip and antenna with the much lower cost of cost of the pinpoint target that rfid chip and antenna is attached to it than expectation.For example, the Hitachi, Ltd of Tokyo introduced in 2004 chip size be 0.4mm * 0.4mm and cost than market on mu series rfid chip and the antenna of existing rfid chip low 1/3.Other semiconductor maker continues to research and develop their competitive product.

Fig. 1 is the vertical view of ID label 10 with prior art of the rfid chip 12 that is installed on the substrate 15 and independent separate antennas 14.Rfid chip 12 is the integrated circuit that contain the required common circuit of functional rfid device, and the device of independently being made.These integrated circuit (IC)-components use batch processing technology known to a person of ordinary skill in the art to make usually.Usually, make up a plurality of duplicate of basic designs on large-scale semiconductor wafer, independently chip is separated from each other and combines with other discrete parts thereafter.

For the ID label 10 of Fig. 1, other discrete parts are antennas 14, and this antenna 14 allows rfid chip 12 circuit and external challenges devices communicating and permission the energy electromagnetism to be sent to rfid chip 12 so that the power electronics for wherein comprising.Because the useful working range of rf antenna is the direct function of area coil, thus antenna 14 multiturn coil more much bigger that be area ideally than rfid chip 12, thus big as far as possible efficient working range can be provided.Antenna 14 normally will stick to the independent discrete coil that forms of substrate 15 subsequently, or directly be deposited on the metal level on the substrate 15 during the formation of online circle.

The ID label 10 common following structures of Fig. 1: at first make rfid chip 12 and antenna 14 as individual components, parts 12 and 14 are mounted to substrate 15 and antenna 14 is electrically connected with rfid chip 12.For this purpose, make the rfid chip 12 that has two

ohm connection pads

16 and 17, the free end 18 of

antenna

14 and 19 can join on these two pads.

Though the construction process of ID label 10 look simple directly, be actually quite difficult but in practice process, carry out with the repetitive accuracy of height.This difficulty mainly is owing to connection pads small size on the rfid chip; Just in the requirement that before the engagement step of this process the

free end

18 and 19 of antenna 14 accurately is positioned on

pad

16 and 17; And must between antenna end and connection pads, form accurately machinery and ohm extra demand that engages.The cost of estimating the ID label of the type shown in the production drawing 1 is: rfid chip 12 accounts for 1/3; Antenna 14 accounts for 1/3; Assembling accounts for 1/3.Along with the reduction of rfid chip physical size, these difficulties and the assembly cost of the ID label of the correct work of assembling also correspondingly increase.

Fig. 2 shows a kind of new method that is used to get rid of the difficulty of assembling the ID label with independent rfid chip and antenna element of making in this area.As shown in the drawing, manufacturing has the rfid chip 22 of formation on substrate 25 and the ID label 20 of antenna 24.Because antenna 24 forms in the lump with rfid chip 22 during chip manufacturing proces, connect so between rfid chip 22 and antenna 24 free ends, form ohm automatically.This " on-chip coil " method has been eliminated the engagement step that expends cost and associated difficulty.

Though should " on-chip coil " solution eliminate the problem that is associated with the joint of discrete parts in ID set of tags process of assembling really, it has but introduced the some restrictions to the efficient working range of the ID label of making according to this technology.Because " on-chip coil " ID label is to use integrated circuit batch processing technology to make, so antenna size has been subjected to the very big restriction of the size of the tube core produced.For example, the working range of the announcement of a kind of commercialization " on-chip coil " ID label is limited in ultimate range 3.0mm.Though this is enough to some specialized application, it is inappropriate that so little working range is used the current great majority of looking forward to of ID label.

A kind of United States Patent (USP) of attempting in announcement on July 3 calendar year 2001 the 6th that is entitled as " Radio Frequency Identification Transponder Having Integrated Antenna " of the working range of expansion " on-chip coil " ID label, 288, have disclosedly in No. 796, disclosing of this patent is incorporated herein by reference.According to the instruction in this list of references, antenna can be installed on the rfid chip or under chip on form.Antenna have common formation its with the multiturn coil of the parallel plane spiral coil of main body of rfid chip.In order to increase the inductance of aerial coil, and increase the working range of ID label thus, can on antenna chip, form high magnetic permeability layer.Though this biasing has increased the working range of " on-chip coil " ID label really, its requirement can increase manufacturing cost and output capacity is had some additional process steps of potential impact, and the antenna that has relatively than small size only can be provided.

So the existing RFID label that comprises RFID label with discrete integrated circuit (IC) chip and antenna and " on-chip coil " variant thereof is still suffering the major defect with the limited efficient working range of the inquiry/fetch equipment that is associated.

Summary of the invention

The present invention includes a kind of method and system that is used to provide the RFID label of the working range that has the ID label increase more suitable than known size.

From the device aspect, the present invention includes the combination of RFID label, comprise rfid integrated circuit and antenna, and have the first passive antenna circuit of first capacitor that comprises first multiturn coil and be connected to this first coil with frequency of operation.This passive antenna circuit has and the essentially identical resonant frequency of the frequency of operation of RFID label.

First coil has its central opening and is spiral structure greater than the basic of antenna size so that passive antenna circuit and RFID label can with the antenna assemblies that is positioned at this central opening together and can be aligned to first coil-induced mutual.When assembled, this first coil basically with the antenna coplane.

In an optional embodiment, the present invention also comprises the second passive antenna circuit that contains second multiturn coil and second capacitor, and this second passive antenna circuit has and the essentially identical resonant frequency of the resonant frequency of the first passive antenna circuit.This second multiturn coil has central opening and is spiral structure greater than the basic of the outer warp of first coil, so that the first and second passive antenna circuit can be mutual in order to induction each other with first coil assembling of the central opening that is positioned at second coil.When assembled, first and second coils are coplane basically.

From the process aspect, the present invention includes the method for working range that a kind of expansion has the RFID label of rfid integrated circuit and antenna, this method contains and has the following steps:

(a) provide the rfid integrated circuit with frequency of operation and the RFID label of antenna;

(b) provide the passive antenna circuit of first capacitor that has first multiturn coil and be connected to this first coil, this passive antenna circuit has and the essentially identical resonant frequency of above-mentioned frequency of operation; And

(c) it is mutual to make up the induction that this RFID label and passive antenna circuit be used between first coil and the antenna each other.

First coil has the central opening greater than antenna size; And combination step (c) preferably includes first coil location is become to make the step of its central opening around antenna.Combination step (c) also preferably includes arranges antenna and first coil so that their steps of coplane basically.

This method also comprises the steps:

(d) provide the second passive antenna circuit of second capacitor that has second multiturn coil and be connected to this second coil, this second passive antenna circuit has and the essentially identical resonant frequency of the resonant frequency of first passive electric circuit; And

(e) it is mutual to make up the induction that this first passive antenna circuit and the second passive antenna circuit be used between first coil and second coil each other.

Second coil has the central opening greater than the size of first coil; And combination step (e) preferably includes second coil is prevented to become to make the step of its central opening around first coil.Combination step (e) also preferably includes arranges first coil and second coil so that their steps of coplane basically.

The invention provides whole advantages of " on-chip coil " ID label and discrete parts RFID label, but the working range much larger than known device also is provided.The working range that increases is greater than known RFID tags more than five times according to estimates.

Characteristic for a more complete understanding of the present invention and advantage are tackled subsequently detailed description with the accompanying drawing and are made reference.

Description of drawings

Fig. 1 is the vertical view of ID label with prior art of rfid chip and stand-alone antenna.

Fig. 2 is the vertical view of ID label with prior art of rfid chip and integrally formed antenna.

Fig. 3 is the synoptic diagram according to the ID label of the rfid of having chip of the present invention and passive antenna.

Fig. 4 shows the vertical view of the first embodiment of the invention with single passive antenna.

Fig. 5 shows the vertical view of the optional embodiment of the present invention with additional passive antenna.

Embodiment

Now turn to accompanying drawing, Fig. 3 shows the synoptic diagram of the principle of the invention.Seen in figure from then on, " on-chip coil " RFID label 30 has rfid integrated circuit (IC) chip 32 and the integrally formed antenna of making 34 on integrated circuit substrate 35.With antenna 34 placed adjacent be passive antenna circuit 36 with coil 37 and tuning capacitor 38.Coil 37 has much larger than the area of antenna component 34, and two elements are aligned to induction each other alternately.

Tuning capacitor 38 allows to select the resonant frequency of passive antenna circuit 36 so that be complementary with the resonant frequency of the circuit that comprises rfid integrated circuit 32 and antenna component 34, thereby makes their inductive coupling maximum.

When broadcasting had the interrogating signal of the frequency of operation of selecting for RFID label 30 in the scope of passive antenna circuit 36, this interrogating signal was transferred into antenna component 34 by passive antenna circuit 36 sensings, enters rfid integrated circuit 32 then.When integrated circuit 32 sent response to this interrogating signal, this response at first by antenna component 34 broadcasting, by passive antenna circuit 36 sensings, and was transferred into the remote inquiry system.Because the scope of passive antenna circuit 36 is more much bigger than the scope of RFID label 30,, promptly be equivalent to about five times of its normal range of operation so increase the working range that passive antenna circuit 36 has greatly been expanded RFID label 30.

Fig. 4 shows the first embodiment of the present invention with single passive antenna circuit 40.Seen in figure from then on, passive antenna circuit 40 comprises that each end all is coupled to the multiturn coil 42 of the different pole plates of tuning capacitor 44.Coil 42 has even as big as holding the central opening part of RFID label (such as label 30).Coil 42 can be formed by any desired mode, such as above-mentioned printing of silver slurry or copper deposition technique.Capacitor 44 can be discrete parts element or the element that uses semiconductor fabrication (deposition, mask, etching etc.) formation.Must carefully select the value of capacitor 44, make the resonant frequency of passive antenna circuit 40 and the frequency of operation of RFID label 30 be complementary.Preferably RFID label 30, antenna 42 and capacitor 44 are installed on certain shared installation surface (not shown), this shared installation surface is normally by being fit to the mounted substrate that material is made arbitrarily.For example, if the embodiment of Fig. 4 is designed to clothes, installation surface clothes paper label normally then.Similarly, if the embodiment of Fig. 4 is designed to the compact package product, the installation surface surface of this product encapsulation itself normally then.

At work, when broadcasting had the interrogating signal of the frequency of operation of selecting for RFID label 30 in the scope of passive antenna circuit 40, this interrogating signal was transferred into antenna component 34 by passive antenna circuit 40 sensings, enters rfid integrated circuit 32 then.When integrated circuit 32 sent response to this interrogating signal, this response at first by antenna component 34 broadcasting, by passive antenna circuit 36 sensings, and was transferred into the remote inquiry system.Because the scope of passive antenna circuit 40 much larger than the scope of RFID label 30, so increase the working range that passive antenna circuit 40 has greatly been expanded RFID label 30, promptly is equivalent to about five times of its normal range of operation.

Fig. 5 shows the second embodiment of the present invention with two passive antenna circuit.Seen in figure from then on, according to arranging the first passive antenna circuit 40 with identical mode shown in Figure 4 so that it is around RFID label 30.The second bigger passive antenna circuit 50 have each end all ohm be connected to the relatively large telefault 52 of each pole plate of second capacitor 54.The coil 42 of central opening in the coil 52 even as big as holding the first passive antenna circuit 40.By selecting to have the capacitor 54 of desired value, just passive antenna circuit 50 can be tuned to the frequency identical with the first passive antenna circuit 40.Except the size of coil 52 was wanted obvious size greater than coil 42, the structure of antenna 52 and capacitor 54 was identical with the structure of coil 42 and capacitor 44 basically.

The work of Fig. 5 embodiment with in the embodiment of Fig. 4, described similar.When broadcasting has the interrogating signal of the frequency of operation of selecting for RFID label 30 in the scope of the second passive antenna circuit 50, this interrogating signal is by the second passive antenna circuit, 50 sensings, be transferred into the first passive antenna circuit 40, be transferred into antenna component 34 then, enter rfid integrated circuit 32 again.When integrated circuit 32 sent response to this interrogating signal, this response at first by antenna component 34 broadcasting, by passive antenna circuit 40 sensings, and was transferred into the second passive antenna circuit 50, is transferred into the remote inquiry system again.Because the scope of the second passive antenna circuit 50 is much larger than the scope of the first passive antenna circuit 40 and RFID label 30, so increase the working range that the second passive antenna circuit 50 has just further expanded the embodiment of Fig. 4.

Interval between the width of the number of turn, absolute coil line segment and passive coil 42 and 52 each coil turn all can be selected by design.Usually, should select coil 42 and 52 size so that area coil much larger than the element that this coil surrounded, so that sufficient physical space is provided and provides for besieged element much larger than the inductance of the inductance of chip coil 34.Yet the size that the target of this label should be installed is relatively thereon set the external diameter of passive coil rightly.Thus, for example, if label will be used for following the tracks of a small-sized jewelry, then the external diameter of this passive coil should be less than the size of this part jewelry.

Should be noted that, be not passive antenna circuit 40 and 50 accurately must be placed with one heart with respect to RFID label 30.As long as passive antenna coil 42 and 52 is the center with chip coil 34 substantially and can promotes each other that the abundant electromagnetism between the telefault is mutual just enough.Therefore, the assembling of RFID label and one or two passive antenna circuit does not need accurate alignment procedure, has reduced assembly cost thus.In addition, because can make the passive antenna circuit with extremely low cost, institute thinks that the RFID label adds one or two passive antenna circuit and can not increase cost of products basically, but the working range of extended RFID tag significantly.

ID label according to teaching manufacturing of the present invention (mainly is to have eliminated the engagement step that relates to aerial coil and rfid chip in that the various advantages that provided by " on-chip coil " ID label are provided, and the cost advantage of mass disposal) time, also provide according to estimates under the situation of only using the single passive antenna circuit just than the working range of the big increase more than five times of working range of known " on-chip coil " ID label.

Though described the present invention with reference to concrete preferable realization, can utilize various modifications, optional structure and equivalence techniques scheme and do not deviate from spirit of the present invention.For example, though described the present invention with reference to " on-chip coil " RFID label, also can consider to use RFID label fully with discrete rfid integrated circuit and antenna.Similarly, though passive coil 44,54 is illustrated and is described as single layer coil, also can utilize as required to have two-layer or more multi-layered multiturn coil.In addition, though describe with reference to closed loop coil and show the present invention, also can consider dipole antenna.Therefore, the above should not be interpreted as limitation of the present invention, because the present invention is only defined by claims.

Claims

With contain rfid integrated circuit with a frequency of operation and a kind of RFID label of antenna and combine, first capacitor that the first passive antenna circuit comprises first multiturn coil and is connected to described first coil, described passive antenna circuit has and the essentially identical resonant frequency of described frequency of operation, and described first coil has basic central opening and being aligned to around described RFID label and is used for described antenna induction mutual.
2. invention as claimed in claim 1 is characterized in that, described first coil basically with described antenna coplane.
3. invention as claimed in claim 1 is characterized in that, described first coil has the basic spiral structure that is.
4. invention as claimed in claim 1, it is characterized in that, also comprise the second passive antenna circuit that contains second multiturn coil and second capacitor, the described second passive antenna circuit has and the essentially identical resonant frequency of the resonant frequency of the described first passive antenna circuit, and described second multiturn coil has basic central opening and being aligned to around described first coil and is used for described first coil-induced mutual.
5. invention as claimed in claim 4 is characterized in that, described second coil basically with the described first coil coplane.
6. invention as claimed in claim 4 is characterized in that, described second coil has the basic spiral structure that is.
7. an expansion has the method for working range of the RFID label of rfid integrated circuit and antenna, and described method comprises the steps:

(f) provide and contain the rfid integrated circuit with a frequency of operation and the RFID label of antenna;

(g) provide the passive antenna circuit of first capacitor that has first multiturn coil and be connected to described first coil, described passive antenna circuit has and the essentially identical resonant frequency of described frequency of operation; And

(h) induction that is used between described first coil and the described antenna each other of combination described RFID label and described passive antenna circuit is mutual.
8. method as claimed in claim 7 is characterized in that, described first coil has the central opening greater than the size of described antenna; And wherein said combination step (c) comprises makes the step of its central opening around described antenna with described first coil location one-tenth.
9. method as claimed in claim 7 is characterized in that, described combination step (c) comprises described antenna and described first coil arrangement are become to make their steps of coplane basically.
10. method as claimed in claim 7 is characterized in that, also comprises the steps:

(d) provide the second passive antenna circuit of second capacitor that has second multiturn coil and be connected to described second coil, the described second passive antenna circuit has and the essentially identical resonant frequency of the resonant frequency of described first passive electric circuit; And

(e) induction that is used between described first coil and described second coil each other of the combination described first passive antenna circuit and the described second passive antenna circuit is mutual.
11. method as claimed in claim 10 is characterized in that, described second coil has the central opening greater than the size of described first coil; And wherein said combination step (e) comprises makes the step of its central opening around described first coil with described second coil location one-tenth.
12. method as claimed in claim 10 is characterized in that, described combination step (e) comprises described first coil and described second coil arrangement is become to make their steps of coplane basically.