Method and apparatus for providing information concerning products, using radio frequency transmissions

A method and apparatus for providing information concerning products, using radio frequency transmissions. A host computer transfers information relating to a product to a radio frequency transmitter. The information is transmitted to a transceiver built into a label for the product, the label being located near a shelf of a gondola that is holding the product. The transmission from the transmitter to the transceiver may be made through one or more repeaters. A label transceiver for another product can act as a repeater, upon instruction from the host computer. When the intended label transceiver correctly receives the information concerning the product, it retransmits an acknowledgement back to the host computer along the same transmission path by which the information reached the transceiver. The transceiver stores the information relating to the product in the label. The transceiver and label are powered by a photovoltaic cell that transforms ambient light into electrical energy. If the ambient light decreases, in order to save electrical energy, the transceiver is first turned off. If it is necessary to save further electrical energy, the label display is next turned off. If the ambient light then increases, the display and then the transceiver are turned back on.

FIELD OF THE INVENTION 
This invention relates generally to methods and apparatus for providing 
product information, and more particularly, to a method and apparatus for 
providing information concerning products, using radio frequency 
transmissions. 
BACKGROUND OF THE INVENTION 
Typically, the sales of products in supermarkets and other commercial 
stores are dependent upon proper presentation of the products to 
consumers. Accordingly, it has become a standard for such products to be 
displayed on shelves so that they may be selected. In addition to the 
visual appeal of the products, of course, both proper product 
identification and price are important factors in product sales. 
Therefore, marketers have been encouraged to market products by precisely 
identifying each product and its price, so that members of the public can 
make informed decisions about the product and its price. 
Another factor in the presentation of products is product location. 
Accordingly, marketers have learned to display products two ways. It is 
important for products to be consistently located within a store (and even 
within a chain of stores). But it is also important to be able to 
highlight products with special appeal, such as seasonal items or items 
that have a special low price. Accordingly, a given product can appear at 
more than one place within a store. One place is the product's consistent 
location. The other place is a special location of prominence, which is 
used when the product is on sale. In addition, marketers have learned to 
let their product location evolve slowly. 
As a result, it can be important for a marketer to have a labelling system 
that can be easily changed, so that labels will reflect both the product's 
price as well as its location. For example, a shelf label should be 
changeable to reflect periodic price changes of a given product. The shelf 
label should also be changeable so that it can be used to label different 
products as the array of featured products changes. 
Marketers have also learned of the great advantages of product 
identification systems, such as the Universal Product Code bar code, which 
facilitate tracking of inventory and render the changing of prices very 
easy, since it is only necessary to change the price in an office computer 
to cause the checkout stands to instantaneously begin charging the changed 
price. Therefore, it is advantageous to have a labelling system that can 
be used to track the flow of a particular product, in order to facilitate 
restocking and reordering of the product to allow an adequate inventory of 
the product to be maintained. 
A number of labeling systems have been proposed in the past. In one, labels 
can be placed along the edges of the shelves where they make contact with 
electrical power lines and one or more data lines that carry product 
identification and pricing information to the proper label. One difficulty 
with such a system is that it requires special shelving units and, due to 
its exposure, is susceptible to damage--both accidental and intentional. 
Such a system may also present an electrical shock hazard to the shopping 
public. 
In another system, it has been proposed to power shelving units with 
electrical power from leads located within the shelves, as discussed 
above, while allowing the product identification and pricing information 
to be transmitted to the labels by means of specially located light 
transmitters. One difficulty with such a system, however, is that it is 
not always possible to assure that all labels have been properly 
reprogrammed. The reason is that some label locations may be only 
marginally exposed to the light transmissions, leaving open the 
possibility of misprogramming or the failure to reprogram a given label. 
In addition, light systems are relatively wasteful of power and would not 
work well if the shelving units were not powered from leads located within 
the shelves. 
Battery-powered labelling systems, of course, suffer from the need to 
change the batteries periodically to minimize the chance that a label will 
fail to work properly. Accordingly, it has become important to provide 
such labelling systems with ways to conserve their electrical power. In 
addition, frequent replacement of the batteries raises environmental 
concerns relating to battery disposal. 
Accordingly, it would be advantageous to have a labelling system that could 
economically provide programmable labels which could be reliably 
programmed without consuming significant amounts of electrical power. 
SUMMARY OF THE INVENTION 
According to one aspect, the invention is an apparatus for communicating 
information between a host computer and a first product indicator. The 
apparatus comprises a converter to convert the information to a radio 
frequency signal and a transmitter to transmit the radio frequency signal. 
The apparatus further comprises a first electrical circuit to receive and 
to retransmit the radio frequency signal. In addition, the apparatus 
comprises a receiver to receive the retransmitted radio frequency signal 
and a signal transformer to transform the received retransmitted radio 
frequency signal and to produce information contained in the radio 
frequency signal. 
According to a further aspect, the invention is an apparatus for 
communicating information between a host computer and a product indicator, 
the product indicator being located in an area containing ambient light 
energy. The apparatus comprises a first electrical circuit to convert the 
information to a radio frequency signal and to transmit the radio 
frequency signal. The apparatus also comprises a transducer to receive the 
ambient light energy and to produce therefrom electrical energy to deliver 
to the product indicator and a delivery circuit to deliver the electrical 
energy to the product indicator. Further the apparatus comprises a 
transceiver to receive and retransmit the radio frequency signal, the 
transceiver being located in the area containing the ambient light energy. 
According to another aspect, the invention is a product indicator for 
storing information concerning a product. The product indicator comprises 
a receiver to receive a radio frequency signal containing information 
concerning a product and an address indicative of the product, a storage 
device to electronically store the information concerning a particular 
product with which the product indicator is associated, and a display to 
display the information concerning the particular product with which the 
product indicator is associated. The product indicator further comprises 
an energy source to provide electrical energy to the receiver, the storage 
device, and the display, an electronic circuit to determine the capability 
of the energy source to provide electrical energy to the means for 
receiving the radio frequency signal, to the display and to the storage 
device, and a controller to control the delivery of the electrical energy 
if the energy source is not capable of providing the electrical energy to 
all of the receiver, the display and the storage device. 
According to a still further aspect, the invention is a method for 
communicating information between a host computer and a first product 
indicator. The method comprises the steps of a) converting the information 
to a radio frequency signal; b) transmitting the radio frequency signal; 
c) receiving and retransmitting the radio frequency signal; d) receiving 
the retransmitted radio frequency signal; and e) transforming the received 
retransmitted radio frequency signal to produce information contained in 
the radio frequency signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a block diagram of an overall labelling system for use in 
identifying products using radio frequency transmissions. FIG. 1A is a 
schematic cross sectional perspective drawing of a label used in 
connection with the present invention. The labeling system 10 includes a 
number of gondolas 12, each of which includes a number of shelves 14 whose 
edges 16 are shaped to receive removable programmable labels 18. Each 
label 18 includes a radio frequency receive/transmit antenna 40, a liquid 
crystal display (LCD) 70, a photovoltaic cell 72, and various other 
electronic components (to be described subsequently). The outward 
appearance of each label 18 is very similar to the labels sold by 
Electronic Retailing Systems International of Darien, Connecticut. The LCD 
70 and the photovoltaic cell 72 appear on the exterior of the label 18, 
while the antenna 40 (a ferrite core antenna) and the various electronic 
components are placed inside the label 18. The programmable labels 18 are 
designed to be difficult for unauthorized persons to remove from the 
shelves 14. 
Each label 18 has a unique address of 32 bits, which is assigned to the 
label 18 during the manufacturing process and maintained in a label ID 
register in the label 18. This assignment can be made by cutting links 
within a printed circuit board in the label, or by special coding in an 
ASIC that is incorporated in the label 18. Each label 18 can also contain 
other information, such as information that is to be displayed on the LCD 
70, including the product price, the product's unit price, the number of 
facings (i.e., the lineal amount of shelf space allocated to the product, 
the recommended order quantity, the weekly movement of the product and the 
amount of the product in transit. 
The labelling system 10 also includes a host computer 20 that contains 
inventory, price and product identification information. The host computer 
20 is connected to a number of transmitters 22 which receive product price 
and identification information from the computer 20 and transmit radio 
frequency signals containing this information to a number of repeaters 24 
that are strategically located on the ceiling 26 (or other appropriate 
surface) of the store. The radio frequency signals can be produced in 
accordance with standard digital communications techniques as described in 
"Digital Communications Fundamentals and Applications," by John Proakis 
(McGraw-Hill) and "Digital Communications," by Bernard Sklar 
(Prentice-Hall). 
The radio frequency signals will operate activate a label 18 at distances 
of up to at least 150 feet. Their center frequencies can be chosen at 13, 
27 or 49 MHz. A lower center frequency allows the ASIC in the label 18 to 
use less power, allows for lower risk in the ASIC design and allow for 
greater coverage due to RF bending and reflections. Potential interference 
at the frequency is also a consideration. The center frequency is 
established by a synthesizer in the label 18 which is described 
subsequently. The minimum acceptable number of center frequencies is two; 
optimally the number of center frequencies is five or more. The label 18 
starts operation at a default center frequency but can be reprogrammed to 
another center frequency by the base system controlled by the host 
computer 20. 
The labelling system 10 may also include an exciter 150 which can be used 
to retrieve an address from a label 18. The exciter 150 can also cause a 
label 18 to perform a self-test and to provide further information which 
is stored in the label 18. Finally, the exciter 150 can completely program 
a label 18. The exciter 150 is connected to the host computer 20, from 
which it receives its instructions and to which it transmits any 
information it retrieves from a label 18. 
The exciter 150 includes a microprocessor 152, a power supply 154, and a 
transceiver 156. The microprocessor 152 and the transceiver 156 receive 
power from the power supply 154. The microprocessor 152 includes a memory 
in which data from the host computer 20 and data from the label 18 can be 
stored. The microprocessor 152, under direct command from the host 
computer 20, or operating from commands in the microprocessor memory that 
were downloaded from the host computer 20, causes the transceiver 156 to 
transmit a RF signal to the nearby label 18. The RF signal includes the 
commands. 
The nearby label 18 responds to the RF signal in one of several different 
ways. For example, if the commands are prompting commands, the label 18 
responds by transmitting a return RF signal, containing information, back 
to the exciter 150. This information includes data stored in the label 18 
for example, the label's address). The transceiver 156 in the exciter 150 
receives the return RF signal, and the microprocessor 152 processes the 
return RF signal and determines the information contained therein. The 
exciter 150 can then store the information in the memory of the 
microprocessor 152, or transmit the information back to the host computer 
20. The label 18 could also be commanded to perform a self-test, contained 
in a program stored in the memory of the microprocessor 152, which 
exercises the electronic components of the label 18, and to then issue a 
report to the exciter 150 via a return RF signal. 
If desired, the exciter 150 can be handheld, which allows its use on 
installed labels 18. The exciter works by transmitting an RF signal to the 
label 18, causing the label 18 to emit its address, as if it were 
acknowledging the receipt of a RF signal containing information. This 
feature is useful when first programming the label 18, since the label 18 
can be given a paper tag which describes a product with which the label 18 
is to be associated. The tag includes both a printed description of the 
product and the universal product code (UPC) bar code for the product. If 
the bar code is first read by a bar code scanner associated with the host 
computer 20 and then the label 18 is caused to produce its address, the 
host computer 20 will associate that label's address with the product, 
until the label 18 is associated with another product by repeating the 
same process. 
In addition to including the product information, the signals include 
address information which determines which of the labels 18 are to receive 
which information. 
The radio frequency signals are received by the labels 18, where their 
address information is checked against the receiving label's address. If a 
label 18 has an appropriate address, it receives the remainder of the 
information in the radio frequency signals and transmits an acknowledge 
signal (ACK) which is returned to the host computer 20 along the same 
sequence of transmitters and repeaters as the radio frequency signals 
followed, but in the reverse order. This is called a "retransmit on error" 
system. The receiver 28 can be built into the transmitter 22. 
In order to ensure that each label 18 receives the signals that are 
intended for it, the labels 18 also form a network of secondary repeaters. 
The labels 18 are equipped to process all signals that they receive and to 
retransmit all signals that they are not directed to retransmit. In this 
way, every label 18 can receive its intended signal through multiple 
paths, thereby greatly reducing the chance that it will not receive the 
necessary programming information. Each signal includes various fields 
which hold important information concerning its destination or origin, any 
instructions it may include, any data it carries, and a cyclic redundancy 
check (CRC) to verify correct receipt of the same signal that was 
transmitted. When a signal passes from a transmitter to a label 18 through 
a series of repeaters, each repeater notes the destination address and 
awaits the return of the ACK signal. Therefore, when the receiver to which 
the host computer 20 is attached receives an ACK signal, the signal's 
address tells the origin of the ACK signal. 
The data are transferred to the labels 18 at a rate of 10 kilobits per 
second, with a minimum bit error rate of approximately 10 -9, if error 
detection is used. The photovoltaic cell 72 will respond to any 
illumination in excess of about 20 lux. Security provisions are given to 
the labelling system 10 by encrypting the transmissions. One suggested 
standard is provided by IEEE 802.11, with a polynomial of 1+x -4+x -7. 
It is also desirable to make the labels 18 transportable. That is, each 
label 18 can be removed from one shelf 14 and relocated at any other 
desired shelf 14. Therefore, it is necessary for each label 18 to have its 
own transportable electrical energy transducer, the photovoltaic cell 72. 
The photovoltaic cell 72 is capable of converting the ambient light energy 
to electrical energy to supply the electrical energy needs for its 
attached label 18. 
The labels 18 are subject to a number of conditions which demand special 
performance. For example, even if there is a great deal of light within 
the store where the labels 18 are in use, it is possible for a given label 
18 to be shadowed by a consumer who is incidentally standing between the 
label 18 and its main source of light, thereby causing the label 18 to 
lose electrical energy. If the blockage condition lasts too long, the 
affected label 18 adopts a power-down mode in which it first shuts down 
the included transceiver 34. If the shadowing lasts too long, the affected 
label 18 next begins to shut down its display 36, and only retains its 
information stored in its internal memory. 
Typically, this latter condition continues during the period when the store 
lights are turned off if the store is closed during night hours. Under 
these conditions, the label 18 assumes a low power consumption role which 
is reversed when the photovoltaic cell 72 on the label 18 again receives 
adequate amounts of ambient light energy. As the amount of light energy 
increases, the label 18 first begins to activate its display. As the 
amount of available light energy continues to increase, the label 18 next 
powers up its receiver (and transmitter, if so equipped) until it is again 
fully functional. 
FIG. 2 is a schematic diagram showing how FIGS. 2(a) and 2(b) are to be 
placed. FIG. 2(a) is a first portion of a schematic diagram of a product 
information transceiver for use with the system shown in FIG. 1. FIG. 2(b) 
is a second portion of a schematic diagram of a product information 
transceiver for use with the system shown in FIG. 1. The transceiver 38, 
which can be incorporated in a single application-specific integrated 
circuit (ASIC) chip, is attached to an antenna 40 (not shown) which is 
used for both receiving and transmitting the radio frequency signals 
containing the information describing the product and the label address, 
as well as the radio frequency signals containing acknowledgement 
information. The transceiver 38 includes a central control unit 42, a 
voltage controlled oscillator (VCO) and frequency synthesizer 44, a 
transmit logic circuit 46, an amplifier/FSK demodulator 48, a receiver 
logic circuit 50, an address and control multiplexer 52, and data and data 
retention registers 54 and 56, respectively. 
In addition, the transceiver 38 includes a display controller 58, a clock 
circuit 60, a voltage generator 62, a timer block 64, and a power monitor 
66. The transceiver 38 is connected to an external bandpass filter 68, a 
label identification register (not shown), a liquid crystal display 70 
(not shown), a conventional crystal 71, a photovoltaic cell 72 (not 
shown), as well as a 50 microfarad capacitor 74 (also not shown). The 
external bandpass filter 68 is 32 kHz wide and the crystal 71 operates at 
approximately 32 kHz. 
Under control of the central control unit 42, the VCO 44 receives data and 
frequency signals from the central control unit 42 and modulates them on a 
radio frequency (RF) carrier signal which it transmits to the transmit 
logic circuit 46, as well as providing an unmodulated RF signal which is 
transmitted to a mixer 76. The mixer 76, which is enabled by the central 
control unit 42, also receives the signal from the antenna 40 to produce 
an intermediate frequency signal that contains the information originally 
transmitted. The information is encoded in frequency shift keyed form. The 
intermediate frequency signal is filtered by the external bandpass filter 
68 and then fed to the amplifier PSK demodulator 48, which is enabled 
under control of the central control unit 42. The output of the amplifier 
FSK demodulator 48 is transmitted to the receiver logic circuit 50, which 
is also enabled by the central control unit 42, and receives label 
identification information concerning the particular transceiver 38. The 
label identification information is stored in a label identification 
register (not shown) which is external to the transceiver 38. 
The receiver logic circuit 50 produces a number of outputs. Some of these 
signals are transmitted to the central control unit 42. They are an 
address or command match signal, a new message signal and a CRC mismatch 
signal. The address or command match signal is a signal indicating whether 
the address contained in the information encoded in the radio frequency 
signal matches the address of the transceiver 38. If the address matches, 
the central control unit 38 operates to produce other information from the 
demodulated radio frequency signal. If the signal contains a command 
match, the central control unit 42 will operate in accordance with the 
command. The new message signal informs the central control unit 42 that 
the demodulated radio frequency signal contains a new message. The CRC 
mismatch signal indicates whether a CRC check has indicated that the 
information contained in the demodulated radio frequency signal has been 
properly decoded. If so, the central control unit 42 causes the 
transmission of an acknowledge (ACK) signal and oversees operation of the 
transceiver, based on the information contained in the demodulated radio 
frequency signal. 
The receiver logic circuit 50 also produces address and control signals 
which are transmitted to the address and control multiplexer 52. The 
address and control multiplexer 52 also receives control signals from the 
central control unit 42. The control signals are used to provide an 
address and other control signals to the register file 54. The register 
file 54 also receives data from the receiver logic circuit 50 and causes 
the storage of data, which it transmits back to the central control unit 
42, and to the proper location in the data retention register 56. 
The voltage controlled oscillator 44 also produces an output signal when 
required by the central control unit 42. The output signal from the 
voltage controlled oscillator 44 is transmitted to the transmit logic 
circuit 46, which is enabled by the central control unit 42. 
Based on the information received by the central control unit 42, the 
central control unit 42 controls the operation of the LCD 70 which is 
built into the label of which the transceiver 38 is a part. The display 
controller 58 receives both control and data signals from the central 
control unit 42 and produces proper data and addressing signals to cause 
the desired product identification and pricing information to be shown on 
the LCD 70. The external crystal 71 produces a signal which is received by 
the clock circuit 60, which, in turn, produces clock signals required by 
the receiver logic 50, the VCO 44, the amplifier FSK demodulator 48, the 
voltage generator 62, and the control unit 42. The voltage generator 62 
receives the voltage produced by the photovoltaic cell 72 and produces 
therefrom the supply voltage which it transmits to the display controller 
58, the power monitor 66, and the capacitor 74. The capacitor 74 stores 
any excess charge produced by the photovoltaic cell 72, for use if the 
output of the photovoltaic cell 72 temporarily decreases. The power 
monitor circuit 66 produces three threshold signals which indicate the 
voltage level that is currently being produced by the photovoltaic cell 
72. If the voltage produced by the photovoltaic cell 72 is currently 
sufficient to provide power to the radio frequency circuitry, the display 
and the information storage registers, all three of the threshold signals 
are on. If, however, the voltage produced by the photovoltaic cell 72 is 
currently not sufficient to simultaneously provide power to the radio 
frequency circuitry, the display and the information storage registers, 
the threshold signal controlling the radio frequency circuitry is turned 
off, disabling the radio frequency circuitry. If the voltage produced by 
the photovoltaic cell 72 further degrades, the threshold signal 
controlling the display is turned off, causing the LCD 70 to blank out. 
This technique preserves the information which the LCD 70 is intended to 
display during those periods when there is not enough ambient light to 
produce a sufficiently large voltage to power all of the circuitry of the 
label. 
The timer block 64 receives a timer value from the central control unit 42 
and produces a load signal and a time out signal in response. 
FIG. 3 is a flow chart describing the programming of the inventive system. 
In operation, the host computer 20 of the inventive system 10 determines a 
product whose label information is to be changed. The host computer 20 can 
make this determination with the help of human intervention through the 
use of conventional human/computer interface devices such as a keyboard 
and a display, or the host computer 20 can make the determination 
independently of human interaction (block 100). An example of the latter 
is when a series of price changes are to be made effective at a particular 
time--say, at midnight of a predetermined day. The host computer 20 then 
specifies the address(es) of the label(s) that are to have changes in 
information (block 102). The host computer 20 accomplishes this by 
reference to a database which it maintains to specify current and future 
product price and description data. 
After the address and information have been specified, the host computer 20 
transfers these data to the transmitter(s) 22 which broadcast narrowband 
RF signals containing the data directly to the addressed label 18, to 
repeaters 24, and/or to label repeaters 30 (block 104). The addressed 
label(s) 18 should receive the information within a specifiable period of 
time (blocks 106 and 108). When the addressed labels(s) 18 verify that 
they have correctly received the data, they transmit an acknowledgement 
(ACK) signal back to the host receiver 28, and store the new data for 
display (block 108). The host computer 20 then returns to block 100 for 
further determinations of products whose label information is to be 
changed. 
If the host computer 20 does not receive an acknowledgement of its 
requested transmission from all of the addressed labels 18 (block 110), 
the host computer 20 causes the data to be retransmitted to the addressed 
labels from which it did not receive acknowledgements (block 104). 
FIG. 4 is a flow chart describing the programming of the labels of the 
inventive system. The central control unit 42 of the specific label 18 
continually checks the voltage output of its photovoltaic cell 72 and 
compares the voltage output to three thresholds (block 120). If the output 
voltage is less than the lowest threshold (threshold 3), the central 
control unit 42 removes electrical power from the radio frequency 
circuitry and display circuitry of the label 18, essentially only 
maintaining the information in storage registers (block 122). This 
represents the lowest power consumption condition of the label 18 (other 
than completely off, which condition would require retransmission of the 
information to the label 18). This is the condition that would occur daily 
after the store is closed and most of the lights are turned off, until 
they are turned on again. After ensuring that the electronic circuitry of 
the label 18 is in its lowest power-consumption mode, the label 18 returns 
to block 120. 
If the voltage of the photovoltaic cell 72 is at a higher level (between 
threshold 1 and a higher threshold 2), the label 18 removes power from the 
radio frequency circuitry (block 124). This allows the label 18 to 
continue to display the information with which it has been programmed, but 
does not permit the label 18 to receive any new information from the host 
computer 20. After ensuring that the radio frequency circuitry is turned 
off, while the display circuitry is turned on, the label 18 returns to 
block 120. 
If the voltage from the photovoltaic cell 72 is at a higher level 
(exceeding threshold 2), the label 18 provides electrical power to all of 
its circuitry, including the radio frequency circuitry (block 126). The 
label 18 then checks to determine whether there is any new label 
information being transmitted or repeated (block 128). If not, the label 
18 returns to block 120. Otherwise, the label 18 determines whether the 
information is addressed to the particular label 18 (block 130). If it is 
not, the label 18 retransmits the information, if the label 18 is so 
instructed (block 132) and returns to block 120. Otherwise, the label 18 
checks to determine whether the information that is directed to it has 
been received properly (block 134). If not, the label 18 enters a mode in 
which it waits for retransmission of the information and returns to block 
120. 
While the label 18 is waiting for transmission of the information, it can 
power down if its source of electrical power is at all marginal. In one 
embodiment, the label 18 can conserve electrical power by turning off its 
receiver, which it reactivates occasionally to determine whether a message 
directed toward the label 18 has been sent. Alternatively, in the wait 
mode, the label 18 can receive instructions causing it to shut down, can 
respond to an internal clock. Otherwise, the label 18 sends an 
acknowledgment signal (block 136), stores and displays the new information 
(block 138), and returns to block 120. 
The preferred embodiment of the present invention has been described in 
detail sufficient for one skilled in the electronics and radio frequency 
arts to understand the invention. Such skilled persons, however, could 
devise alternative embodiments to that described herein while remaining 
within the scope of the appended claims. Accordingly, the scope of the 
invention is to be limited only by the appended claims.