CN100557986C - The transmitter and the control method thereof that are used for electronic article monitoring system - Google Patents
The transmitter and the control method thereof that are used for electronic article monitoring system Download PDFInfo
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- CN100557986C CN100557986C CNB2005100878360A CN200510087836A CN100557986C CN 100557986 C CN100557986 C CN 100557986C CN B2005100878360 A CNB2005100878360 A CN B2005100878360A CN 200510087836 A CN200510087836 A CN 200510087836A CN 100557986 C CN100557986 C CN 100557986C
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Abstract
The method of operating of the transmitter in a kind of control eas (EAS) system has been described, comprise: any one of a plurality of send channels that are coupled is to corresponding antenna, the modulator that is configured in each send channel is given corresponding antenna with the output modulation signal, the feedback of each modulation signal is provided, and based on the operation of each modulator of feedback adjusting.A kind of EAS transmitter and EAS system have equally also been described.
Description
The cross reference of related application
The present invention relates to and require to enjoy on May 11st, 2004 submitted to, patent application serial numbers is No.60/570,032, title is the priority of the provisional application of " Closes Loop Transmitter Control for Switching Acoustic-MagneticPower Amplifier in an EAS System ", therefore, at this whole its full content of introducing as a reference.
Technical field
The present invention relates generally to that the signal in the electronic article monitoring system generates, more specifically, relate to the system and method that is used for being configured to launching the transmitter amplifier control of the signal that receives by the EAS mark.
Background technology
At the eas sound magnetics or magnetomechanical, perhaps in " EAS ", detection system can encourage the EAS mark by the resonance frequency emission electromagnetic pulse string with mark.When this mark was in the electromagnetic field that transmission burst produces, it began and sound response frequency generation resonance magnetic or magnetic force, and this is that receiver in the detection system can be detected.
The transmitter that uses in these detection systems can comprise the linear amplifier that uses FEEDBACK CONTROL, perhaps uses the switching amplifier of open loop control.Linear amplifier provides good transmitter current to regulate by FEEDBACK CONTROL, but because relatively poor power efficiency, usually about 45 (45%) percent, so cost dearly.Above-mentioned switching amplifier provides good power efficiency, usually about 85 (85%) percent, yet because open loop control and variable loading condition, so the transmitter current level can fluctuate.
The control assembly of prior art is attempted to provide the adjustment of low bandwidth pulse duration by the electric current based on transmission burst mensuration before before, alleviates current fluctuation.In an example, below Fig. 1 and Fig. 2 are provided further description, transmitter components hardware provides the single pulse-width modulator of the single half-bridge amplifier of control, and single half-bridge amplifier has a plurality of loads that are connected across the parallel connection in the amplifier output.In this configuration, the minimum higher antenna of antenna ratio impedance of impedance receives more electric current, and causes the power difference of launching electrical level or the output of each antenna.In addition, the current sense hardware in the prior art systems makes only to have in any given moment and supply with to give the electric current of single load can be sensed.Especially, after whole transmission burst is finished,, estimate the electric current that is used for load by current sample is averaged.
Summary of the invention
In one embodiment of the invention, a kind of method of controlling the transmitter in the electronic article monitoring system is provided, this method can comprise: each of a plurality of send channels of coupling transmitter is to corresponding antenna, the modulator that is configured in each send channel is given corresponding antenna with the signal of exporting after modulating, the feedback of signal after each modulation is provided, and based on the operation of each modulator of feedback adjusting.
In another embodiment of the present invention, provide a kind of transmitter that is used for electronic article monitoring system.This transmitter can comprise a plurality of antenna and a plurality of send channels that are arranged to the signal emission.Each send channel all is coupled to a corresponding antenna, and each send channel all comprises and is configured to signal is supplied with amplifier to its antenna, is configured to provide the signal the modulated modulator to amplifier, is configured to sensing and is put on the sensing circuit of the magnitude of current of antenna and the controller that is configured to receive from sensing circuit the magnitude of current that senses by amplifier.This controller is configured to control based on the magnitude of current that senses the operation of modulator.
In another embodiment, provide a kind of electronic article monitoring system, can comprise at least one mark, at least one is configured to receive the receiver of emission and the transmitter that at least one comprises a plurality of send channels from mark.Each send channel can be configured to transmit, and makes mark resonance when being marked near the send channel with box lunch.Each send channel can be configured to utilize feedback to control the power output of send channel independently.
Description of drawings
Different embodiment for a better understanding of the present invention, following detailed description should be read as a reference in conjunction with the accompanying drawing of back, the part that wherein same numeral is same.
Fig. 1 is the block diagram of the known transmission machine that uses in eas (EAS) system.
Fig. 2 is the block diagram of the controlled function used in the transmitter of Fig. 1.
Fig. 3 sets up according to one exemplary embodiment of the present invention, comprises the block diagram of the transmitter of the independent feedback control that is used for each antenna load.
Fig. 4 is the block diagram of exemplary controlled function embodiment that is used for the transmitter of Fig. 3.
Fig. 5 is the block diagram of EAS system that can include the transmitter of Fig. 3.
Embodiment
Easy and easy for what explain, will the present invention be described in conjunction with each embodiment of the present invention at this.Yet, it should be recognized by those skilled in the art that the features and advantages of the present invention can implement by various configurations.Therefore should be understood that embodiment described here occurs as example rather than restriction.
Fig. 1 is the block diagram that is used for the transmitter 10 of eas (EAS) system.Particularly, transmitter 10 can comprise a plurality of the emission respectively from the antenna 12,14,16 and 18 of the signal of amplifier 20 receptions.Controller 30 in the transmitter 10 can be configured to the current measurement carried out based on during the previous transmission burst, and the adjustment of low bandwidth pulse duration is provided.In this embodiment, as shown in Figure 1, controller 30 can comprise the single pulse-width modulator 32 of control amplifier 20, and in one embodiment, amplifier 20 can be to have the antenna 12,14,16 that is connected across the parallel connection in the amplifier output 22 and 18 single half-bridge amplifier.
For the control of pulse-width modulated device 32 is provided, current sensing circuit 34,36,38 and 40 can be electrically connected to respectively on each corresponding antenna 12,14,16 and 18, and is configured to the magnitude of current that sensing is delivered to each respective antenna 12,14,16 and 18.The current measurement that sensing circuit 34,36,38 and 40 all will put on antenna 12,14,16 and 18 offers multiplexed (muxing) circuit 42.Multiplex electronics 42 can be controlled by control algolithm parts 44.Control algolithm parts 44 determine which current sensing circuits output will be switched by multiplex electronics 42, handle by analog to digital converter 46 being used for.Therefore, in the sequence by 44 controls of control algolithm parts, the magnitude of current that puts on each antenna 12,14,16 and 18 is fed by A/D converter 46 and control algolithm parts 44, with the operation of control impuls width modulator 32.
Yet in such configuration, antenna 12,14,16 and 18 plays shunt, and the antenna that the antenna ratio with lowest impedance has higher resistance receives more electric current.To be each antenna 12,14,16 all have different slightly impedances with 18 to the result usually, and thereby launch different quantity of power.This may not wish to occur in the EAS system transmitter.In addition, the current sense hardware in such system (just, current sensing circuit 34,36,38 and 40, and multiplex electronics 42) makes that the electric current that only puts on single load (antenna) at any one time can be sensed.After transmission burst was finished, by the current sample that receives in control algolithm 44 is averaged, estimation put on the electric current of each load.
Fig. 2 is the block diagram of explanation control algolithm parts 44 functions.Especially, sample buffer 60 receives the sampling (all shown in Figure 1) of the electric current that puts on antenna 12,14,16 and 18 of sensing from A/D converter 46.As above, sample buffer 60 receives the sampling that relates to one of antenna 12,14,16 and 18 at any one time.Then as known in the art, this sampling is processed to determine its amplitude by envelope detector 62.
The amplitude of the current sample of sensing is imported into pulse-width modulator control renewal equation 68 fully then.70 receptions of pulse-width modulator (PWM) controlling value and the relevant input of the desirable electric current output of tranmitting frequency, the phase place that transmits and PWM hardware.Calculating unit 72 can be configured to be known as state variable (shown in Figure 1) sometimes for determining minimum PWM controlling value 70 by PWM hardware by the load that amplifier 20 drives.
Fig. 3 has illustrated the embodiment of the multi-channel transmitter 100 that is used for the EAS system, and it handles above-mentioned different antennae impedance and the variation of the transmitting power that causes.In the embodiment shown, four independently transmitter channel 102,104,106 and 108 be illustrated, but be appreciated that if given EAS system needs, can use the transmitter channel of any amount.In addition, although followingly be described, be to be understood that transmitter channel 104,106 and 108 can be disposed similarly at transmitter channel 102.In addition, any use is less than or can be disposed similarly more than the embodiment of four transmitter channel.
In exemplary embodiment, transmitter 100 utilizes the real-time FEEDBACK CONTROL of each switch power amplifier.As described shown in the embodiment, each transmitter channel, for example transmitter channel 102, can comprise the independent switch amplifier 110 that is equipped with pulse-width modulator 112 real-time FEEDBACK CONTROL.Such configuration provides the power efficiency and the low cost of switching amplifier, and with the common similar Current Regulation level of Current Regulation level relevant with linear amplifier.Because in this embodiment, the power that produces in each independent transmission machine channel approximately is to use transmitter that single channel (and amplifier) drives four antennas (for example, transmitter 10 shown in Fig. 1) 1/4th of the middle power that produces, so the electronic unit that uses in send channel 102,104,106 and 108 is compared with the electronic unit that uses in the product of transmitter 10, littler, dissipate still less power and wholely have a cheaper cost.
Still with reference to Fig. 3, transmitter channel 102 can comprise current sensing circuit 114, be configured to measure, or sensing amplifier is 110 that provide, the magnitude of current that is used to drive the load that is provided by antenna 116.In one embodiment, current sensing circuit 114 can be configured to output voltage.Current sensing circuit 114 provides feedback signal 118 (for example, voltage), and this signal can be imported into analog to digital converter (ADC) 120, and is converted into digital signal 122.This digital signal 122 can be imported into control algolithm parts 124.Control algolithm parts 124 comprise that for example, process chip is as microprocessor, microcontroller or digital signal processor (DSP) and relevant programming thereof.In optional embodiment, control algolithm parts 124 can use the combination of discrete electronic component to implement.
The operation of the embodiment of control algolithm parts 124 is shown in Figure 4.As shown in Figure 4, the digital signal 122 of the electric current that representative senses in output place of amplifier 110 can be imported into control algolithm parts 124.Control algolithm parts 124 can be configured to determine the value of feedback signal.In the embodiment shown, as known in the art, the value of digital signal 122 can use envelope detector 130 to determine.Those of ordinary skills can understand, and other known detectors also can be used.
In addition, the value of digital signal 122 (output 140) can be imported into ratio, integration, differential, or " PID " controller 150.In the embodiment shown, the current amplitude by the hope of set point 152 representative can deduct from the current amplitude (output 140) that calculates, and produces error signal 154.Error signal 154 can multiply by proportional gain constant 160 then, or Kp, producing proportional controlling value 162, or Cp.Error signal 154 also can be input in the integrator equation, and shown in the discrete integrator among Fig. 4 170, the output 172 of this integrator is multiplied by storage gain constant 174, or Ki, is worth 176 to produce integral control, or Ci.Finally, error signal 154 also can be imported in the differential equation, and shown in the discrete differential device 180 among Fig. 4, the output 182 of this differentiator can be multiplied by differential gain constant 184, or Kd, with generation derivative controlling value 186, or Cd.
Three control assembly values 162,176 and 186, or Cp, Ci and Cd, can be summed producing total controlling value 190, or C.This controlling value 190 can be limited in the allowed input range of pulse-width modulator 112 by the amplitude limit function that is realized in the amplitude limiter 192.The control signal 194 that obtains can be imported into (shown in Figure 3) in the pulse-width modulator 112.The enforcement of the discrete integration and the differential equation generally is for known in those skilled in the art on digital signal processor and other processing unit.Equally, the selection of suitable gain constant Kp, Ki and Kd can be depended on other parameters of system, for example the variable gain that produces owing to the variation in the discrete electronic component in sensing circuit 114 and the amplifier 110.
Although be described to digital signal processor (DSP), signal processing described here can be moved on microprocessor, microcontroller and other processing topological structures, for example, blur and/or neural control structure, observer/estimator or state space control structure and other topological structures, and do not change embodiment described here essence.Equally, the integrated progress of semiconductor has produced various will be for example multiplexed, analog-to-digital conversion and modulation and has been integrated in integrated circuit in the single process chip.
Therefore in operation, the control signal 194 that is produced by control algolithm parts 124 is based on by (both shown in Figure 3) of current sensing circuit 114 at the magnitude of current of antenna 116 place's sensings.This control signal 194 can be imported into pulse-width modulator 112 (shown in Figure 3), and this pulse-width modulator produces the pulse-modulated signal of the pulse duration with the parameter that depends on control signal 194.The pulse-modulated signal that produces can amplify (illustrating at Fig. 3) by amplifier 110 then, and is used to drive transmitting antenna 116.Transmission burst output produces the electric current that puts on antenna 116.This electric current can also be by current sensing circuit 114 sensings, and this current sensing circuit provides and feeds back to control algolithm parts 124.Like this, feedback is used to be provided with the width by the transmit signal pulse of amplifier 110 outputs.
Provide the independence of the magnitude of current that puts on many antenna loads to control in real time at Fig. 3 and the described EAS system transmitter 100 of Fig. 4.So, can dispose the EAS transmitter, so that can be by all send channels 102,104,106 with 108 the time, independently current surveillance for each antenna of transmitter 100, can be controlled desirable amount of transmission power individually.For example, compare, because semiconductor is integrated and also because the reduction of the power relevant with the send channel that separates (generation with dissipate), reduced the cost of transmitter with transmitter 10 (shown in Figure 1).The net effect of higher integrated and littler, more cheap power component is, uses the total cost of a plurality of independent transmission channels and load to be lower than to use single channel to come cost for a plurality of load supply powers.In addition, compare with known transmitter configuration, transmitter configuration described here has also been brought and circuit protection, thermal management and the relevant advantage of electric current adjustment.
Fig. 5 is the explanation of EAS system 200, and this system can comprise the embodiment of transmitter 100 described here.Especially, EAS system 200 can comprise first antenna pedestal 202 and second antenna pedestal 204, and wherein each can comprise many antennas (for example, antenna 16).Antenna in the antenna pedestal 202 and 204 can be connected to control unit 206, and control unit 206 can comprise transmitter 100 and receiver 210.In control unit 206, controller 212 can be configured to communicate with external equipment.In addition, controller 212 can be configured to control the emission timing from transmitter 100, and the reception of receiver 210 places expections, make antenna pedestal 202 and 204 can be used for the signal emission of EAS mark 220 and the reception of the frequency that produces by EAS mark 220.System 200 only means an example, and it represents many EAS system.For example, in optional embodiment, control unit 206 can be placed in one of antenna pedestal 202 and 204.In another embodiment, only receiving can be as the part of EAS system 200 from the additional antenna of the frequency of EAS mark 220.Single control unit 206 in pedestal or that place discretely also can be configured to control many group antenna pedestal.
As the result who comprises embodiment described here, () performance for example, transmitter 100 so that the raising of power efficiency to be provided, and allows the independent sensing of many antenna loads to have improved transmitter in the EAS system (for example, EAS system 200).Simultaneously, these transmitters provide reliable transmitter current level under the variable load condition, and provide redundant fault to handle with low cost.
The variation and the modification that should be appreciated that various embodiments of the invention can be made, and do not depart from the scope of the present invention.Should be appreciated that equally the scope of various embodiments of the invention is not interpreted as being limited to specific embodiment disclosed herein, but explains according to claim according to aforementioned open the reading time.
Claims (6)
1. method of controlling the transmitter in the electronic article monitoring system, described method comprises:
In a plurality of send channels of described transmitter each is coupled on the corresponding antenna;
Dispose the modulator in each send channel, give corresponding antenna with the signal after the output modulation;
The feedback of the signal after providing each to modulate;
Operation based on described each modulator of feedback adjusting comprises: sensing puts on the magnitude of current of corresponding antenna and changes the electric current that is sensed is digital value; And
Allocation ratio integral differential controlled function, with the value that reduces the electric current sensed and the error between the desirable current value,
Wherein, the operation of adjusting modulator also comprises: the width of adjusting each pulse-modulated signal that puts on corresponding antenna, the described proportion integration differentiation controlled function of programming is with the amplitude limit function of output controlling value in the amplitude limiter, and wherein said controlling value is limited to the permission input range of described modulator.
2. according to the method for claim 1, it is characterized in that described controlling value is configured to comprise ratio, integration, differential component.
3. transmitter that is used for electronic article monitoring system comprises:
A plurality of antennas that are arranged to the signal emission; With
A plurality of send channels, each described send channel all are coupled on corresponding one or more described antennas at least, and each described send channel comprises:
Be configured to provide the amplifier of signal to corresponding described antenna;
Be configured to provide signal after the modulation to the modulator of described amplifier;
Be configured to sensing puts on the magnitude of current of described antenna by described amplifier sensing circuit; With
Be configured to receive from described sensing circuit the controller of the magnitude of current that is sensed, described controller is configured to control based on the magnitude of current that is sensed the operation of described modulator,
Wherein, described controller comprises:
Be configured to determine the mathematics parts of the value of the electric current that sensed; And
Be configured to receive the current magnitude that sensed, and reduce the current magnitude that sensed and the proportional plus integral plus derivative controller of the error between the desirable current value,
Described modulator comprises pulse-width modulator, described pulse-width modulator is couple to described amplifier input terminal and is connected the output of described proportional plus integral plus derivative controller and the amplitude limiter between the described modulator, and wherein said amplitude limiter arrives the export-restriction of described proportional plus integral plus derivative controller the permission input range of described modulator.
4. according to the transmitter of claim 3, wherein said amplifier comprises switching amplifier.
5. according to the transmitter of claim 3 or 4, further comprise analog to digital converter, it is digital value that described analog to digital converter is configured to change the electric current that is sensed, and described digital value is received by described controller.
6. according to each transmitter among the claim 3-4, wherein said proportional plus integral plus derivative controller is configured to receive the current magnitude that sensed, reduce the current magnitude that sensed and the error between the desirable current value and output controlling value to described amplitude limiter, and described controlling value comprises ratio, integration, differential component.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US57003204P | 2004-05-11 | 2004-05-11 | |
| US60/570,032 | 2004-05-11 | ||
| US11/121,897 | 2005-05-04 |
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| Publication Number | Publication Date |
|---|---|
| CN1728569A CN1728569A (en) | 2006-02-01 |
| CN100557986C true CN100557986C (en) | 2009-11-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB2005100878360A Active CN100557986C (en) | 2004-05-11 | 2005-05-11 | The transmitter and the control method thereof that are used for electronic article monitoring system |
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| CN (1) | CN100557986C (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4683461A (en) * | 1985-09-17 | 1987-07-28 | Allied Corporation | Inductive magnetic field generator |
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2005
- 2005-05-11 CN CNB2005100878360A patent/CN100557986C/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4683461A (en) * | 1985-09-17 | 1987-07-28 | Allied Corporation | Inductive magnetic field generator |
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| CN1728569A (en) | 2006-02-01 |
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