Embodiment
Below in conjunction with exemplary embodiment radio frequency identification (RFID) antenna and RFID label are described.
[the first embodiment]
Fig. 2 shows the RFID label 100 according to the first embodiment.
With reference to figure 2, RFID label 100 comprises semi-conductor chip 110 and antenna 140.Antenna 140 comprises electric conductor 120 and a plurality of conductor 130.
Semi-conductor chip 110 is integrated circuit (IC) chips, and comprises less radio-frequency (RF) transmitting/receiving circuit, steering logic and storer.Semi-conductor chip 110 is by antenna 140 emissions or receive wireless frequency.
Conductive contact member such as band are formed on the load point (for example electric power provides a little) 127 and 128 of electric conductor 120.Semi-conductor chip 110 is installed on the conductive contact member.
Electric conductor 120 is main bodys of antenna 140, and it has the shape of ellipse or polygon (for example rectangle and pentagon).Electric conductor 120 has formed the closed loop except load point 127 and 128.Electric conductor 120 and conductor 130 can be formed by same material.Electric conductor 120 is electrically connected with semi-conductor chip 110, and conductor 130 is not electrically connected with semi-conductor chip 110.
The electric current electric conductor 120 of flowing through.Electric conductor 120 comprises: be connected to semi-conductor chip 110 First Line 121 and 122, be connected to First Line 121 and 122 two ends the second line 123 and 124, be connected to the 3rd line 125 at the second line 123 and 124 two ends.First Line 121 and the 122 and the 3rd line 125 are arranged accordingly, and the second line 123 and 124 corresponds to each other.First Line 121 and the 122 and second line 123 and 124 account for about 60% to 80% of electric conductor 120 in length.
Conductor 130 is divided at least two parts with open loop form by electricity.Conductor 130 is not electrically connected with electric conductor 120.Conductor 130 is formed on the outside of electric conductor 120.
Conductor 130 comprises the first conductor 131 and the second conductor 132.The first conductor 131 is corresponding to First Line and second line 121,122,123 and 124 of electric conductor 120.The second conductor 132 is corresponding to the first conductor 131 and the 3rd line 125.First Line to the three lines 121 to 125 of electric conductor 120 and conductor 130 be standoff distance (d) spatially.This distance (d) can be constant or change for every line.
The two ends 135 of the first conductor 131 and the second conductor 132 predetermined gap (G) of being separated by.Gap (G) is electric areas of disconnection.Gap (G) can equal the 3rd line 125 of electric conductor 120 and the distance between the second conductor 132
The second conductor 132 can form rectilinear form, or the two ends 136 of the second conductor 132 can be crooked.The second conductor 132 is longer than the 3rd line 125 that extends in X-direction, and the two ends 136 of the second conductor 132 can be positioned at inside or the outside of the extended line of drawing from the two ends of the first conductor 131 parallel with Y-axis.
Conductor 130 and electric conductor 120 can form identical shape or similar linear.For example, conductor 130 and electric conductor 120 can form polygon or the elliptical line of symmetrical or asymmetric pattern.And, can change the live width of conductor 130 and electric conductor 120 according to the characteristic of the hope of antenna 140.
The feed-in electric current (i) that is provided by semi-conductor chip 110 can flow through electric conductor 120 clockwise or counterclockwise.Signal energy with radio frequency is radiated to conductor 130 from the line 121,122,123,124 and 125 of electric conductor 120 gradually with the form in electric field or magnetic field.As a result, the signal energy by electric conductor 120 has produced coupling phenomenon at conductor 130 places.
In other words, electric energy shifts between electric conductor 120 and conductor 130 with the Mutual Inductance Coupling type, has produced inductive coupling.Because the inductive coupling between conductor 130 and the electric conductor 120, the electric capacity of semi-conductor chip 110 can be reduced, and the resonant frequency of semi-conductor chip 110 can be broadened.
In the RFID of this embodiment label 100, the electric current that is provided to electric conductor 120 by semi-conductor chip 110 excites conductor 130, causes inductive coupling.Inductive coupling is the strongest around semi-conductor chip 110 the 3rd line 125 farthest.
The input resistance component of the feed-in of antenna 140 part and conductor resistance reciprocal proportional.Can regulate the input resistance component by the inductive coupling coefficient between electric conductor 120 and the conductor 130.Therefore, since the decline of the input resistance that the miniaturization of antenna causes can be solved.In addition, the inductance that can easily regulate electric conductor 120 according to size and the position of the feed-in of antenna 140 part.
The Mutual Inductance Coupling coefficient can followingly represent:
Wherein, μ
0The expression permeability of free space, l
bExpression electric conductor 120 is at the length of Y direction, l
aExpression electric conductor 120 is in the length of X-direction, and d represents the distance between electric conductor 120 and the conductor 130.
The impedance of feed-in loop can be expressed as:
Z
loop=j2πfL
loop
L wherein
LoopThe self-induction of expression feed-in loop.
In the antenna 140 of RFID label 100, the input impedance component only is the function of Mutual Inductance Coupling coefficient (M), and reactive component only is the inductance L of feed-in loop
LoopFunction.Therefore, can regulate distance between electric conductor 120 and the conductor 130 according to the Mutual Inductance Coupling coefficient.
Fig. 3 and Fig. 4 show the radiation pattern according to the antenna of the first embodiment RFID label.
With reference to Fig. 3, the antenna of RFID label has isotropic radiation pattern.This radiation pattern is to be produced by the inductance of electric conductor and conductor coupling.The horizontal component of radiation pattern is produced by the line that is parallel to Z axis and X-axis of antenna, and the vertical component of radiation pattern is produced by the line that is parallel to Y-axis of antenna.θ represents the angle on XY plane,
Represent the measured angle about Y-axis.
Fig. 4 shows radiation pattern according to the antenna of the RFID label of the first embodiment with three dimensional form.With reference to Fig. 4, this antenna has the isotropic radiation pattern about X, Y and Z direction.Therefore, when RFID label and RFID reader communication, form hardly zero-signal zone, like this, the RFID label can be in all directions and the RFID reader communication.
Fig. 5 shows the curve map according to the radar cross section (RCS) of the antenna of the RFID label of the first embodiment.RCS is when the RFID reader is changed 0 °, 30 °, 60 ° and 90 ° about the angle θ of RFID label, and with the angle of RFID reader about the RFID label
When changing 0 °, 30 °, 60 ° and 90 °, the measured volume reflection from antenna.As shown in Figure 5, the reflection from the antenna of RFID label to the RFID reader almost is constant in all directions.
Fig. 6 shows the RFID label 100 on the basic components 150 of being installed in according to the first embodiment.
With reference to Fig. 6, RFID label 100 is installed in front surface or the rear surface of basic components 150.Use conducting resinl to form pattern at basic components 150 by silk screen print method, in order to form antenna 140.Like this, the electric conductor 120 of antenna 140 and conductor 130 can form at grade.
Basic components 150 are formed by the non-conductive material of flexibility.For example, flexible non-conductive material comprises: polyethylene terephthalate (PET), polyimide (PI), PEN (PEN), Polyvinylchloride (PVC), paper, acetic acid esters (acetate), polyester, tygon, polypropylene, the polypropylene with calcium carbonate, acrylonitrile-butadiene-styrene copolymer (ABS), or plastics.Basic components 150 can be formed by one or more or its combination of listed material.According to the purposes of RFID label 100, the antenna that is installed on the basic components 150 can have various shapes, such as polygon and ellipse.
And, comprise that the basic components 150 of RFID label 100 can be coated with the insulating protective layer (not shown).This protective seam can be formed by the material that equals or be similar to the material of basic components 150.For example, this protective seam can use heating and pressurized heat plastic material to form.Because RFID label 100 is between basic components 150 and protective seam, so RFID label 100 can be protected, and be not subjected to environmental factor such as collision and moist impact.In addition, in this embodiment, antenna 140 can be by forming electric conductor (or conductor), form conductor (or electric conductor) at protective seam at basic components 150, and basic components 150 and protective seam are combined to form.
Fig. 7 shows the installation according to the semi-conductor chip 110 of the first embodiment.
Shown in (a) among Fig. 7, semi-conductor chip 110 can be installed on the conductive pad 111 that is connected with electric conductor 120 by upside-down method of hull-section construction.Alternatively, shown in (b) among Fig. 7, semi-conductor chip 110 can be connected with electric conductor 120 by line 113.That is to say, semi-conductor chip 110 and electric conductor 120 can be electrically connected by upside-down method of hull-section construction, line connection method or according to other method of using.
Fig. 8 shows the rfid system according to the first embodiment.
With reference to Fig. 8, rfid system comprises RFID label (or transponder) 100 and reader (or plug-in reader) 160.RFID label 100 and reader 160 utilize the short-distance wireless communication frequency band to communicate with one another.The short-distance wireless communication frequency band be for example 860MHz to the UHF frequency band of 950MHz.Rfid system can use various wireless communication frequency band according to application.That is to say that this embodiment is not limited to the UHF frequency band.
RFID label 100 is installed on the basic components 150, and communicates by letter with reader 160 by contact or non-contacting method.RFID label 100 transmits the data (such as identification information) that are stored in the storer by the backscattering communication law.
RFID label 100 can be the passive RFID tags that comprises the active RFID tag of battery or do not comprise internal electric source (such as battery).Under latter event, RFID label 100 can be used to come work from the electric wave energy of reader 160.
Fig. 9 shows example according to the change of the RFID antenna of the first embodiment to Figure 13.Fig. 9 is exemplary antenna to RFID antenna shown in Figure 13.That is to say that RFID antenna of the present invention can have various structures according to application.
With reference to Fig. 9, RFID label 200 comprises semi-conductor chip 210 and pentagon antenna 240.Antenna 240 comprises electric conductor 220 and the conductor 230 that forms with two pentagon patterns.
Electric conductor 220 can have 60 ° to 120 ° interior angle θ 0 and the θ 1 in the scope.The interior angle θ 2 of conductor 230 is determined by the interior angle of electric conductor 220.In the interior angle of electric conductor 220 or conductor 230 one can be in 60 ° to 320 ° scope for example, in order to minimize the wave interference between the adjacent lines.
With reference to Figure 10, RFID label 300 comprises the antenna 340 of semi-conductor chip 310 and round rectangle.Antenna 340 comprises electric conductor 320 and conductor 330.The angle of electric conductor 320 or conductor 330 is round.Conductor 330 comprises the first conductor 331 and the second conductor 332.Conductor 330 can form the reservation shape with at least one smooth curve part, such as oval, rhombus and trapezoidal.
With reference to Figure 11, RFID label 400 comprises semi-conductor chip 410 and the antenna 440 with predetermined aspect ratio.Antenna 440 comprises electric conductor 420 and conductor 430.The aspect ratio of electric conductor 420 or conductor 430 can be 4: 5 or 5: 4.
With reference to Figure 12, RFID label 500 comprises semi-conductor chip 510 and the antenna 540 with different interior angles.Antenna 540 comprises electric conductor 520 and conductor 530.Electric conductor 520 comprises First Line 521 and 522, and the angle that forms each other is θ 3; Form angle theta 4 between the second line 523, itself and First Line 521.Angle θ 3 is equal to or greater than 180 °, and angle θ 4 is less than 120 °.For example, angle θ 3 can be in 180 ° to 300 ° scope, and angle θ 4 can be in 60 ° to 120 ° scope.Conductor 530 is formed at the outside of electric conductor 520, and has the interior angle that is similar to electric conductor 520.
With reference to Figure 13, RFID label 600 comprises semi-conductor chip 610 and antenna 640.Antenna 640 comprises electric conductor 620 and is formed at the conductor 630 in electric conductor 620 outsides.The two ends 636 of the second conductor 632 of conductor 630 bend towards the two ends 635 of the first conductor 631 of conductor 630.The two ends 636 of the second conductor 632 can extend upward by the line L1 parallel with the 3rd line 625 of electric conductor 620.
According to the example of the change of the first embodiment and the first embodiment, the antenna of RFID label comprises electric conductor and the conductor that forms dual structure.Therefore, by the inductive coupling between electric conductor and the conductor (or Mutual Inductance Coupling input method), the RFID label can have isotropic pattern.
[the second embodiment]
Figure 14 shows the second embodiment to Figure 15.Figure 14 shows the sectional view according to the RFID label of the second embodiment.Figure 15 shows the skeleton view according to the application example of the RFID label of the second embodiment.
Comprise semi-conductor chip 710 and antenna 730 with reference to Figure 14 and 15, RFID label 700, and dielectric body 740.
Semi-conductor chip 710 places in the dielectric body 740, and is with 722 to be connected with being connected with the first band with being connected.First is connected with the back of antenna 730 with 722, and second is with 724 to be connected with ground.
Because semi-conductor chip 710 places the inside of dielectric body 740, so semi-conductor chip 710 can easily be installed.Dielectric body 740 can be formed by frame resistance 4 (FR-4).
Antenna 730 is formed on the dielectric body 740 with the form of planar inverted F type antenna (PIFA).For example, antenna 730 can comprise upper plate 732 and from the side plate 731 of upper plate 732 bendings.In the scope of 2mm, the area of upper plate 732 is approximately 50*30mm to the height of side plate 731 at 1mm.Antenna 730 can have various sizes according to application.
Antenna 730 can comprise at least one slit 735 in the upper plate 732 that is electrically connected with semi-conductor chip 710.The distance B 2 that slit 735 is predetermined with semi-conductor chip 710 intervals.
The slit 735 of antenna 730 is formed in the upper plate 732 with the form of rectangular aperture (or straight slot), and does not extend to the outside of upper plate 732.Can regulate the width in slit 735, so that the capacitive reactance of semiconductor 710 can be the complex conjugate of the induction reactance of antenna 730: (jx ,+jx).
Slit 735 can be formed on the direction vertical with direction of current or cross over shortest path, thereby prevents that electric current from flowing through along shortest path.Because antenna 730 comprises slit 735, so the effective length of antenna (electrical length) can be increased in the situation that does not increase antenna 730 sizes.That is to say, can reduce the size of antenna 730.In addition, in order to reduce size, the upper plate 732 that wherein is formed with slit 735 can be formed zigzag.
Current-carrying plate 760 can be attached to the lower surface of RFID label 700, as shown in figure 15.Current-carrying plate 760 can be formed by metal material, and its size can be greater than the size of upper plate 732.
In other words, RFID label 700 is installed on the current-carrying plate 760.In this case, what be connected with semi-conductor chip 710 first is with 722 to be electrically connected with current-carrying plate 760, and the bottom of side plate 731 is electrically connected with current-carrying plate 760.
Although the antenna 730 of RFID label 700 is electrically connected with current-carrying plate 760, antenna 730 can work.
When RFID label 700 and RFID reader communication, semi-conductor chip 710 provides electric current to antenna 730.In antenna 730, electric current (i) flows through around the slit 735 of upper plate 732 and leaves slit 735.
In addition, because slit 735 has changed the path of electric current in the antenna 730, so the electrical length of antenna 730 (effective length) can be increased the length in slit 735.That is to say that the length of antenna 730 can be reduced the length in slit 735.Therefore, the size of RFID label 700 can be reduced.
The RFID label 700 of the second embodiment utilizes predetermined short-distance wireless communication frequency band and reader communication.Here, the short-distance wireless communication frequency band is the UHF frequency band from 860MHz to the 950MHz scope for example.In addition, RFID label 700 provides identifying information by radio communication to reader.RFID label 700 can be the passive RFID tags 700 that comprises the active RFID tag 700 of battery or do not comprise battery.Under latter event, RFID label 700 can utilize the electric wave energy that receives from reader to come work.
Although by in conjunction with the preferred embodiments the present invention having been carried out concrete demonstration and description, be appreciated that those skilled in the art can carry out the change of various forms and details, and do not break away from the spirit and scope of the present invention that limit such as claims.It only is descriptive and the conditional purpose of tool not that preferred embodiment should be considered to.
Therefore, scope of the present invention be can't help detailed description of the present invention and is limited, and is limited by claims, and all differences within this scope will be considered to be included in the present invention.
In RFID antenna and RFID label according to exemplary embodiment of the present invention, the RFID label do not have the RFID label can not with the zero-signal direction of reader communication, so the RFID label can be applied to product reliably.
In addition, because the RFID antenna of RFID label forms simple flat shape by printing, so the RFID label can easily be made.
In addition, have less restriction owing to can use the RFID label aspect the installation site, the rfid system that therefore has the RFID label can be used easily and reliably.
And because the RFID antenna forms seamed crack, so the size of RFID antenna or length can be reduced.
In addition, RFID label even can be installed on the sheet metal, thus improve the applicability of RFID label.