JP2012014383A - Electronic inventory tag system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic inventory tag system which does not require a battery.SOLUTION: The electronic inventory tag system comprises: a feeder line 30 which is laid along a shelf for arranging an article, and constitutes a primary coil; a carrier wave drive circuit 40 which supplies to this feeder line an alternating current modulated by a signal for communication; electronic inventory tags 50A and 50B having a display part 56 for displaying information related to the article and a secondary coil 51. Power feeding to the electronic inventory tags 50A and 50B and communication of the information related to the article are performed through electromagnetic induction between the primary coil 30 and the secondary coil 51. The electronic inventory tag does not require a battery, so that a load of battery replacement is eliminated and an adverse effect on an environment due to disposal of the battery can be avoided.

Description

  The present invention relates to an electronic shelf label system installed on a merchandise display shelf such as a supermarket or an inventory management shelf of a warehouse, and eliminates the need for battery replacement of the electronic shelf label.

In recent years, supermarkets and convenience stores that introduce electronic shelf labels are rapidly increasing.
The electronic shelf label is introduced as a part of the POS system, the price displayed on the electronic shelf label is rewritten by the POS management device, and the settlement at the cash register is performed based on the price.
FIG. 9 shows an electronic shelf label system described in Patent Document 1 below. The electronic shelf label management apparatus 1 is connected to the wireless base stations 3 ₋₁ , 3 _-k via the communication line 2, and each wireless base station has an electronic shelf label installed on the display shelf corresponding to each product. 4 _1-1 ,... Perform wireless communication with 4 _kn to transmit information of the electronic shelf label management device to each electronic shelf label.

As shown in FIG. 10, the electronic shelf label has a commodity price based on the control of the microprocessor 21, the transceiver 21 that performs wireless communication with the wireless base stations 3 ₋₁ , 3 _-k via the antenna 21, and the antenna 22. And the like, a battery monitoring circuit 25, and a battery 26 for supplying power to each unit.
With the introduction of this electronic shelf label, customer complaints resulting from price display mistakes are reduced, and labor costs required to replace price tags can be reduced. In addition, detailed sales strategies such as changing product prices depending on the time of day will be possible.

JP 2001-195660 A

  However, it is said that the battery of the electronic shelf label needs to be replaced in about 3 years. Since the number of electronic shelf labels reaches several thousand to several tens of thousands per store even in small and medium-sized stores, battery replacement of electronic shelf labels imposes a heavy burden on store management. In addition, there is a concern that the large-scale disposal of used batteries may adversely affect the environment.

  The present invention has been made in consideration of such circumstances, and an object thereof is to provide an electronic shelf label system that does not require a battery.

An electronic shelf label system according to the present invention includes a power supply line that constitutes a primary coil, which is laid along a shelf on which articles are placed, and a carrier wave drive circuit that supplies alternating current modulated with a communication signal to the power supply line. An electronic shelf label having a display unit for displaying information related to the article and a secondary coil, and feeding power to the electronic shelf label and communicating information related to the article through electromagnetic induction between the primary coil and the secondary coil; Is performed.
In this system, power supply to the electronic shelf label and communication of information displayed on the electronic shelf label are simultaneously performed through non-contact power feeding.

In the electronic shelf label system of the present invention, it is desirable to arrange a series capacitor between the carrier wave drive circuit and the primary coil of the feeder line, and arrange a parallel resonant capacitor between the terminals of the secondary coil of the electronic shelf label. .
The system (S / P system) in which capacitors in series on the primary side and parallel capacitors on the secondary side are easy to analyze the characteristics of non-contact power feeding, and can easily execute the optimum design of the system.

In the electronic shelf label system of the present invention, the capacity of the series capacitor is C _s , the number of electronic shelf labels is m, the capacity of the parallel resonant capacitor arranged on the electronic shelf label is C _p , the frequency of the carrier wave is f ₀ , The primary leakage reactance at frequency f ₀ in each of the m transformers composed of the primary coil and the secondary coil is converted to x ₁ , the secondary leakage reactance converted to the primary side is converted to x ₂ , and converted to the primary side. when the excitation reactance and x _0,
A value C _p converted to the primary side of the parallel resonant capacitor connected to each of the secondary coils,
C _p = 1 / {2πf ₀ × (x ₀ + x ₂ )} (Equation 1)
Set the series capacitor value C _s to
C _s = (x ₀ + x ₂ ) / {m × 2πf ₀ × (x ₀ × x ₁ / m + x ₁ × x ₂ / m + x ₂ × x ₀ )}
(Equation 2)
It is desirable to set to.
The value C _p of the secondary side parallel resonant capacitor is determined by (Equation 1) so as to resonate with the secondary self-inductance at the power source frequency f ₀ , and the value C _s of the primary side series capacitor has a primary side power factor of 1 It is determined by (Equation 2) so that By doing so, the equivalent circuit of the system becomes substantially equivalent to the ideal transformer, and the system design becomes easy.

  In the electronic shelf label system according to the present invention, the carrier wave drive circuit includes a modulation circuit that outputs a carrier wave having a frequency of 1 kHz to 1 MHz modulated by a signal, a direct current power source that outputs direct current, and a direct current output from the direct current power source. And a drive circuit that converts the signal into an alternating current modulated by a carrier wave and outputs the alternating current.

In the electronic shelf label system of the present invention, the DC power source is driven with a constant current so that a constant current is output from the drive circuit.
By monitoring the output of the DC power supply and driving the DC power supply at a constant current, a constant current can be output from the drive circuit. By making the output from the carrier wave drive circuit to the feed line constant, even if the power of some of the electronic shelf labels changes, the voltage applied to other electronic shelf labels is constant voltage. Become.

In the electronic shelf label system of the present invention, the modulation circuit modulates the carrier wave by ASK (amplitude shift keying).
In ASK modulation, since the frequency does not change, the secondary parallel resonant capacitor can maintain the resonance state.

In the electronic shelf label system of the present invention, communication to each of the electronic shelf labels is performed by a broadcast method.
The price information including the identification information of the electronic shelf label is transmitted by the broadcast method, and each electronic shelf label acquires the information including its own identification information from the information and displays it on the display unit.

In the electronic shelf label system of the present invention, the feeder line is laid in a recess of a cross made of aluminum having a U-shaped cross section, and the electronic shelf label has a mounting means that can be attached to and detached from the cross. However, when it is mounted on the rail with this mounting means, electromagnetic induction between the primary coil and the secondary coil of the electronic shelf label becomes possible. The electronic shelf label is mounted on the aluminum rail and the secondary of the electronic shelf label. When the coil and the feeder line approach, electromagnetic induction between the primary coil and the secondary coil becomes possible. The aluminum bar shields the external magnetic field and suppresses the intrusion of noise.

In the electronic shelf label system of the present invention, it is desirable to provide two Zener diodes connected in series in the opposite direction and connected in parallel with the parallel resonant capacitor between the terminals of the secondary coil of the electronic shelf label.
This Zener diode prevents an overvoltage between the terminals of the secondary coil when the load on the electronic shelf label is extremely small. In addition, the output voltage of the DC power source that is driven by constant current is prevented from becoming excessive.

Moreover, in the electronic shelf label system of this invention, it is preferable to provide an electronic paper as a display part in an electronic shelf label.
Electronic paper only needs to be supplied when rewriting display information, so that power consumption can be reduced.

In the electronic shelf label system of the present invention, since power supply and information transmission are performed in a non-contact manner on the electronic shelf label, it is not necessary to have a battery in the electronic shelf label. Therefore, the burden of battery replacement is eliminated, and adverse environmental effects associated with battery disposal can be avoided.
In addition, since non-contact power supply and information transmission are possible, the electronic shelf label can be sealed and used in a poor environment such as a factory or warehouse where dustproof and waterproof properties are required.

The figure which shows the basic circuit structure of the electronic shelf label system which concerns on embodiment of this invention. The figure (sectional view) which shows the shape of the feeder and electronic shelf label of the electronic shelf label system of FIG. The figure which shows the state in which the feeder of FIG. 2 is installed in a crosspiece (disassembled perspective view) The figure which shows the shape of the electronic shelf label of FIG. 2 (a front view and a back view) The figure (sectional view) which shows the state where the electronic shelf label of Drawing 2 was installed in the cross rail The figure which shows the equivalent circuit of the basic circuit of FIG. The figure which shows the Example of the electronic shelf label system of FIG. 1 (when using electronic paper) The figure which shows the Example of the electronic shelf label system of FIG. 1 (when using a liquid crystal display) Diagram showing a conventional electronic shelf label system Block diagram showing the configuration of a conventional electronic shelf label

FIG. 1 shows a basic circuit configuration of an electronic shelf label system according to an embodiment of the present invention.
The system includes a power supply line 30 constituting a primary coil, a carrier wave drive circuit 40 that supplies alternating current modulated with a communication signal to the power supply line 30, and a product display shelf. A plurality of electronic shelf labels 50A, 50B arranged at the product position are provided.
A series capacitor 31 is disposed between the feeder line 30 and the carrier wave drive circuit 40.
The carrier wave drive circuit 40 converts a modulation circuit 41 that outputs a carrier wave having a frequency of 1 KHz to 1 MHz modulated by a signal wave, a DC power source 42, and a DC from the DC power source 42 into an AC modulated by the carrier wave to supply a power line. And a drive circuit 43 that outputs to 30.

  An electronic shelf label 50 </ b> A (same for 50 </ b> B) includes a secondary coil 51 constituting a non-contact power supply transformer with the primary coil, a parallel resonant capacitor 52 disposed between terminals of the secondary coil 51, and a rectifier bridge 53. 4, a smoothing capacitor 54 for smoothing the rectification generated by the rectifier bridge 53, a display unit 56 for displaying information such as a commodity price acquired through communication, and a power supply to the display unit 56 And a regulator 55 that keeps the voltage and current constant.

  In this system, communication with each of the electronic shelf labels 50A and 50B is performed by a broadcast method, and identification codes of the respective electronic shelf labels 50A and 50B are attached to information transmitted to each of the electronic shelf labels 50A and 50B. Sent. The display unit 56 of the electronic shelf labels 50 </ b> A and 50 </ b> B acquires and displays only information with its own identification code from the signal received through the feeder line 30. The display unit 56 includes a microprocessor (not shown) that performs such processing, but a detailed description of the microprocessor is omitted.

In this system, the modulation circuit 41 of the carrier wave drive circuit 40 ASK modulates the carrier wave with a signal wave. The drive circuit 43 of the carrier wave drive circuit 40 converts the direct current from the direct current power source 42 into alternating current power by using the ASK modulated carrier wave as a switching signal of the inverter circuit, and outputs it to the power supply line 30.
When an alternating current flows through the feeder line 30 (primary coil), an alternating current modulated by a signal is induced in the secondary coil 51 of the electronic shelf labels 50A and 50B by electromagnetic induction between the primary coil and the secondary coil 51. The The alternating current induced in the secondary coil 51 is rectified by the rectification bridge 53, and the voltage / current is controlled to be constant by the smoothing capacitor 54 and the regulator 55, and is supplied to the display unit 56.
Further, the signal multiplexed in alternating current is demodulated, and information with its own identification code is selected and displayed on the display unit 56.

2, 3, 4, and 5 show examples of the installation form of the feeder line 30 and the shape of the electronic shelf label 50. As shown in the cross-sectional view of FIG. 2B and the exploded perspective view of FIG. 3, the power supply line 30 is wound around a horizontally long plate-shaped core 33 fixed to the back side of the horizontally long panel plate 34. The panel plate 34 is accommodated in the recess of the horizontal rail 32 made of aluminum having a U-shaped cross section so that the panel plate 34 appears in the table. The aluminum horizontal bar 32 and the panel plate 34 are set to have a horizontal size corresponding to the length of the place where the shelf label of the product display shelf is arranged, and the wound core 33 has the wound power supply line 30 connected to the panel. As long as it is hidden by the plate 34, it is set as long as possible.
Here, an example in which the power supply line 30 is wound around the plate-shaped core 33 only once is illustrated, but the number of turns of the power supply line 30 is arbitrary.

On the other hand, as shown in the sectional view of FIG. 2 (a), the back view of FIG. 4 (a), and the front view of FIG. And a substrate 57 on the surface of which the display unit 56 is installed, and an attachment means 58 for detachably attaching the substrate 57 to the aluminum crosspiece 32.
FIG. 5 shows a state in which the electronic shelf label is attached to the aluminum horizontal rail 32 by the mounting means 58. In this state, the primary coil of the feeder line 30 and the secondary coil 52 of the electronic shelf label 50 come close to each other, and electromagnetic induction with a non-contact power transformer becomes possible.
The aluminum crosspiece 32 shields an external magnetic field and prevents noise from entering the non-contact power supply transformer.

Next, the operation of the series capacitor 31 disposed on the feeder line 30 and the parallel resonant capacitor 52 disposed between the terminals of the secondary coil 51 of the electronic shelf label 50 will be described.
In this way, when a system (S / P system) in which capacitors in series are arranged on the primary side and parallel on the secondary side is adopted, the characteristic analysis of the non-contact power feeding becomes easy, and the optimum design of the system can be easily executed.
In the case of a system including a plurality of secondary coils as shown in FIG. 1, the S / P type non-contact power supply circuit is represented by the equivalent circuit shown in FIG. 6 on the right side of PP ′ in FIG.
However, for the sake of simplicity, the winding resistance and iron core loss are ignored here. The number m on the secondary side is 2.

In this equivalent circuit, the primary leakage reactance in each of m transformers composed of a primary coil and a secondary coil is converted to x ₁ , the secondary leakage reactance converted to the primary side is converted to x ₂ , and converted to the primary side. it represents the excitation reactance at x _0. x _s1 is the primary leakage reactance of the series capacitor 31, x _p2 is the secondary leakage reactance of the parallel capacitor 52, R ₁ and R ₂ are load resistances, I ₁ and I ₂ are load currents, and V ₂₁ and V ₂₂ are load voltages. Represents.
In this system, the value C _p of the parallel capacitor 52 connected to the secondary coil 51 of each electronic shelf label 50A, 50B is configured to form a resonance circuit with the self-inductance of the secondary coil 51 of each electronic shelf label 50A, 50B. In addition,
C _p = 1 / {2πf ₀ × (x ₀ + x ₂ )} (Equation 1)
And set. f ₀ is the frequency of the carrier wave.

On the other hand, the value C _s of the series capacitor 31 connected to the primary coil (feed line 30) is such that the power factor of the primary power supply becomes 1, that is, the term including the impedance j of the equivalent circuit shown in FIG. Set to 0. When the number of secondary loads is m, C _s is as shown in (Expression 2).
C _s = (x ₀ + x ₂ ) / {m × 2πf ₀ × (x ₀ × x ₁ / m + x ₁ × x ₂ / m + x ₂ × x ₀ )}
(Equation 2)
When C _p and C _s are set in this way, the voltages V ₂₁ and V ₂₂ and currents I ₁ and I ₂ of the load resistors R ₁ and R ₂ can be approximated by the following equations.
V ₂₁ = (V ₁ / b) {R ₁ / (R ₁ + R ₂ )} (Equation 3)
V ₂₂ = (V ₁ / b) {R ₂ / (R ₁ + R ₂ )} (Equation 4)
V ₂₁ + V ₂₂ = V ₁ / b (Equation 5)
I ₁ = I ₂ = (V ₁ / b) {1 / (R ₁ + R ₂ )} (Equation 6)
Here, b = x ₀ / (x ₀ + x ₂ ) (Expression 7)
It is.

As described above, the equivalent circuit of FIG. 6 is equivalent to the circuit of the ideal transformer by (Equation 3) to (Equation 6). The turn ratio b of the ideal transformer does not depend on the values of the loads R ₁ and R ₂ .
Also, the load side impedance Z seen from the power source is
Z = {x ₀ / (x ₀ + x ₂ )} ² × (R ₁ + R ₂ ) (Equation 8)
It becomes.
As described above, even if the power of one electronic shelf label 50A is changed in the S / P method with respect to the change in the feed power, that is, the load resistance, even if the power of one electronic shelf label 50A changes, the other electronic shelf label The power reception of 50B is a constant voltage.
However, there is a risk that the light load power receiving unit will be overvoltage. This countermeasure will be described later.

FIG. 7 shows an embodiment of the circuit configuration of this electronic shelf label system.
The modulation circuit 41 of this circuit oscillates a carrier wave of 100 kHz. When a “1” signal is input from the personal computer 70, the carrier wave is output, and when “0” is input, the carrier wave output is stopped to perform ASK modulation of the carrier wave. Is going.
The DC power source 42 is constituted by a constant current power circuit that is driven at a constant current. This circuit monitors the direct current output to the drive circuit 43 and controls it to have a constant current.
The drive circuit 43 converts the direct current sent from the constant current power supply circuit into alternating current using the modulated carrier wave as a switching signal of the inverter circuit. Therefore, a constant current is output from the drive circuit 43.

Between the terminals of the secondary coil 51 of the electronic shelf label 50, two Zener diodes 71 connected in series in the opposite direction are connected in parallel with the parallel resonant capacitor 52 together with the parallel resonant capacitor 52. The Zener diode 71 acts to prevent overvoltage to a light load by short-circuiting the terminals of the secondary coil 51 to disconnect the load when the load on the electronic shelf label is extremely small.
Further, the demodulator circuit 60 compares the terminal voltage of the secondary coil 51 with the reference voltage by the comparator 61 and demodulates the signal “1” or “0”.

  Here, the electronic paper 72 is used for the display part of the electronic shelf label 50. The electronic paper 72 has a memory property and can continue stable display even when power supply is stopped. Therefore, only when the display of the electronic paper 72 is changed, if the drive circuit 43 is activated and a signal is sent from the personal computer 70, the signal is demodulated by the demodulation circuit 60 and the display of the electronic paper 72 is switched.

  FIG. 8 shows an embodiment in which a liquid crystal display 73 is used as the display unit 56 of the electronic shelf label 50. In order to maintain the display of the liquid crystal display 73, it is necessary to continue power supply to the liquid crystal display 73 and continue to send display signals to the liquid crystal display 73. Therefore, here, the microcomputer 62 is arranged, the information demodulated by the demodulation circuit 60 is held by the microcomputer 62, and the display signal is continuously sent from the microcomputer 62 to the liquid crystal display 73.

Thus, in this electronic shelf label system, since it is not necessary to place a battery on the electronic shelf label, the burden of battery replacement is eliminated. Also, adverse environmental impacts associated with battery disposal can be avoided. In addition, the electronic shelf label can be sealed and used in a poor environment such as a factory or a warehouse.
In addition, an electronic shelf label that uses electronic paper for the display unit consumes power only when the display content is changed, and does not require power to maintain the display. Even if they are arranged, power consumption hardly increases.
In addition, barcodes cannot be displayed with liquid crystal, but barcodes can be displayed with electronic paper, and expansion of applications can be expected.

  The present invention can be used in a wide range of fields, such as sales stores such as supermarkets and convenience stores that display products, warehouses and factories that manage inventory, and the like.

DESCRIPTION OF SYMBOLS 30 Feed line 31 Series capacitor 32 Aluminum crosspiece 33 Plate-shaped core 34 Panel board 40 Carrier wave drive circuit 41 Modulation circuit 42 DC power supply 43 Drive circuit 50A Electronic shelf label 50B Electronic shelf label 52 Parallel resonant capacitor 53 Rectification bridge 54 Smoothing capacitor 55 Regulator 56 Display unit 57 Substrate 58 Mounting means 59 Recessed portion 60 Demodulating circuit 61 Comparator 62 Microcomputer 70 Personal computer 71 Zener diode 72 Electronic paper 73 Liquid crystal display

Claims (10)

A feed line constituting a primary coil, laid along a shelf on which articles are placed;
A carrier wave drive circuit for supplying an alternating current modulated with a communication signal to the feeder line;
An electronic shelf label having a display unit for displaying information on the article and a secondary coil;
The electronic shelf label system is characterized in that power supply to the electronic shelf label and communication of information regarding the article are performed through electromagnetic induction between the primary coil and the secondary coil.   2. The electronic shelf label system according to claim 1, wherein a parallel resonant capacitor is disposed between terminals of a secondary coil of the electronic shelf label. 3. The electronic shelf label system according to claim 2, wherein a series capacitor is disposed between the carrier wave drive circuit and a primary coil of the feeder line, and the capacity of the series capacitor is C _s and the number of the electronic shelf labels. M, the capacitance of the parallel resonant capacitor arranged on the electronic shelf label C _p , the frequency of the carrier wave f ₀ , and the frequency f _{0 in} each of the m transformers composed of the primary coil and the secondary coil. Where x _{1 is the} primary leakage reactance at x ₁ , x _{2 is the} secondary leakage reactance converted to the primary side, and x ₀ is the excitation reactance converted to the primary side,
A value C _p converted to the primary side of the parallel resonant capacitor connected to each of the secondary coils is
C _p = 1 / {2πf ₀ × (x ₀ + x ₂ )}
And the value C _{s of the} series capacitor is
C _s = (x ₀ + x ₂ ) / {m × 2πf ₀ × (x ₀ × x ₁ / m + x ₁ × x ₂ / m + x ₂ × x ₀ )}
Electronic shelf label system characterized by being set to.   3. The electronic shelf label system according to claim 1, wherein the carrier wave driving circuit outputs a carrier wave having a frequency of 1 KHz to 1 MHz modulated by the signal, a DC power source that outputs DC, and An electronic shelf label system comprising: a drive circuit that converts a direct current output from a direct current power source into an alternating current modulated by the carrier wave and outputs the alternating current.   5. The electronic shelf label system according to claim 4, wherein the DC power source is driven with a constant current, and a constant current is output from the drive circuit.   5. The electronic shelf label system according to claim 4, wherein the modulation circuit ASK modulates the carrier wave.   5. The electronic shelf label system according to claim 1, wherein communication with each of the electronic shelf labels is performed by a broadcast method.   2. The electronic shelf label system according to claim 1, wherein the power supply line is laid in a concave portion of a rail made of aluminum having a U-shaped cross section, and the electronic shelf label can be attached to and detached from the rail. An electronic shelf label system, wherein when the mounting means is attached to the crosspiece, electromagnetic induction between the primary coil and the secondary coil of the electronic shelf label becomes possible. .   4. The electronic shelf label system according to claim 2, wherein the electronic shelf label is an element that prevents an overvoltage between terminals of the secondary coil, for example, the parallel resonant capacitor. An electronic shelf label system comprising two Zener diodes connected in parallel with each other and connected in series in opposite directions.   The electronic shelf label system according to claim 1, wherein the electronic shelf label includes electronic paper as the display unit.