System and method for optical data communication

• US 20040044709A1
• Filed: 09/03/2002
• Published: 03/04/2004
• Est. Priority Date: 09/03/2002
• Status: Abandoned Application

• Current Assignee: Light Modulation, Inc.
• Original Assignee: Light Modulation, Inc.
• Inventors: Mason, Matthew, Colby, Daniel, Cabrera, Florencio
• Application Number:
  US10/233,717
• Publication Number:
  US 20040044709A1
• Time in Patent Office: Days
• US Class Current: 708/191
• CPC Class Codes: H04B 10/1149 Arrangements for indoor wireless networking of information
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]
• CPC Class Codes: H05B 47/175 by remote control

Abstract

A system for data communication in a space illuminated by a plurality of illumination sources that are powered by a common power feed. The system includes a power modulation unit which is interposed in the common power feed, upstream of each of the illumination sources. The power modulation unit induces a change in the signal of the power feed in response to received data and effects variations in illumination intensity in the space provided by the illumination sources. The data is provided by a data source computer. At least one optical receiver is in the illuminated space and is in optical communication with at least one of the illumination sources. The optical receiver is responsive to changes in the incident light from the illumination sources resulting from the power modulation unit. The system can be used to communicate and display product data in an electronic shelf tag system.

Claims

1. A method of transmitting data within a network space, comprising:

illuminating the network space with a plurality of illumination sources powered by a common alternating current power main; and

applying a modulation signal to the alternating current power main such that the illumination of each of the plurality of illumination sources is simultaneously modulated in response thereto.

2. The method of transmitting data according to claim 1, wherein at least a portion of said illumination sources have an associated ballast and wherein the modulation signal is induced upstream of each of said ballasts.

3. A system for data communication in a space illuminated by a plurality of illumination sources that are powered by a common power feed, comprising:

a power modulation unit, said power modulation unit being interposed in said common power feed, upstream of each of the illumination sources, and inducing a change in the signal of said power feed in response to received data, said change effecting variations in illumination in the space provided by the illumination sources;

a data source computer, the data source computer being coupled to said power modulation unit and providing data thereto;

at least one optical receiver, said optical receiver being in optical communication with at least one of said illumination sources and being responsive to changes in incident light from said illumination sources resulting from said power modulation unit.

4. The system for data communication in a space illuminated by a plurality of illumination sources according to claim 3, wherein the power modulation unit further comprises:

AC power main input terminals for connection to an external AC power main signal;

a transformer, said transformer having first and second primary terminals, a tapped primary terminal and first and second secondary terminals, the first primary terminal being electrically coupled to the first AC power main input terminal, the first and second secondary terminals being connectable to an external illumination circuit; and

a switching circuit, the switching circuit being interposed between the AC power main input terminals and the transformer, the switching circuit selectively connecting the AC power main terminals to either the first primary and tapped primary terminals or to the first primary and second primary terminals in response to a received external data signal.

5. The system for data communication in a space illuminated by a plurality of illumination sources according to claim 3, wherein the power modulation unit further comprises:

first and second AC power main input terminals for connection to an external AC power main signal;

a transformer, said transformer having first and second primary terminals, a tapped primary terminal and first and second secondary terminals, the first primary terminal being electrically coupled to the first AC power main input terminal;

a single pole, double throw switching circuit, the pole connection of the switching circuit being operatively coupled to the second AC power main input terminal, the switching circuit having a first throw connection electrically connected to the tapped primary terminal of said transformer, the switching circuit having a second throw terminal electrically connected to the second primary terminal of said transformer;

the switching circuit having a control input terminal for receiving a signal to operate the switching circuit between the two switched states of the circuit;

an AC power main sampling circuit, the AC power main sampling circuit being responsive to an applied AC power main signal applied to the AC power main input terminals and generating a clock signal therefrom; and

a data buffer circuit, the data buffer circuit having a data input terminal, a data output terminal and a clock input terminal, the data output terminal being electrically connected to the control input terminal of the switching circuit, the clock input terminal being electrically coupled to the AC power main sampling circuit, and the data input terminal is connectable to an external data source to receive data to be transmitted by the modulation unit.

6. The system for data communication in a space illuminated by a plurality of illumination sources according to claim 3, wherein the optical receiver further comprises:

a liquid crystal display layer positioned to be visible by a user;

a transflective layer positioned behind the liquid crystal display layer;

a photovoltaic layer positioned behind the liquid crystal display layer, the photovoltaic layer receiving at least a portion of the light incident upon the liquid crystal display layer; and

a circuit layer positioned behind the photovoltaic layer, the circuit layer being electrically connected to the liquid crystal display layer and the photovoltaic layer.

7. A power modulation unit which imposes a modulation signal on an AC power main signal, comprising:

AC power main input terminals for connection to an external AC power main signal;

a transformer coupled to the AC power main input terminals, said transformer having a first and second ratio of turns between a primary winding and a secondary winding;

a switching circuit operatively coupled to the transformer, the switching circuit being responsive to a signal to selectively switch between one of the first and second ratio of turns of the transformer;

modulated AC power output terminals coupled to the transformer and for external connection to a lighting load.

8. A power modulation unit which imposes a modulation signal on an AC power main signal, comprising:

first and second AC power main input terminals for connection to an external AC power main signal;

a transformer, said transformer having first and second primary terminals, a tapped primary terminal and first and second secondary terminals, the first primary terminal being electrically coupled to the first AC power main input terminal;

a single pole, double throw switching circuit having a pole connection operatively coupled to the second AC power main input terminal, the switching circuit having a first throw connection electrically connected to the tapped primary terminal of said transformer, the switching circuit having a second throw terminal electrically connected to the second primary terminal of said transformer, the switching circuit having a control input terminal for receiving a signal to operate the switching circuit between the two switched states of the circuit;

an AC power main sampling circuit, the AC power main sampling circuit being responsive to an applied AC power main signal applied to the AC power main input terminals and generating a clock signal therefrom; and

a data buffer circuit, the data buffer circuit having a data input terminal, a data output terminal and a clock input terminal, the data output terminal being electrically connected to the control input terminal of the switching circuit, the clock input terminal being electrically coupled to the AC power main sampling circuit, and the data input terminal is connectable to an external data source to receive data to be transmitted by the modulation unit.

9. The power modulation unit of claim 8, wherein the switching circuit further comprises first and second silicon controlled rectifiers (SCR), the first SCR being coupled between the second AC terminal and the tapped primary terminal, the second SCR being coupled between the second AC terminal and the second primary terminal, the gate of the first SCR is responsive to the data output signal from the data buffer circuit and the gate of the second SCR is responsive to the complement of the data output signal from the data buffer circuit.

10. The power modulation circuit of claim 9, wherein the AC sampling circuit comprises a zero crossing detector to generate said clock signal.

11. The power modulation circuit of claim 9, wherein the AC sampling circuit generates said clock signal in response to the AC power main signal having a value at least equal to a predetermined threshold value.

12. The power modulation circuit of claim 8, wherein the AC sampling circuit generates said clock signal in response to the AC power main signal having a value at least equal to a predetermined threshold value.

13. A power modulation unit which imposes a modulation signal on an AC power main signal, comprising:

AC power main input terminals for connection to an external AC power main signal;

a transformer, said transformer having first and second primary terminals, a tapped primary terminal and first and second secondary terminals, the first primary terminal being electrically coupled to the first AC power main input terminal, the first and second secondary terminals being connectable to an external illumination circuit; and

a switching circuit, the switching circuit being interposed between the AC power main input terminals and the transformer, the switching circuit selectively connecting the AC power main terminals to either the first primary and tapped primary terminals or to the first primary and second primary terminals in response to a received external data signal.

14. An optical receiver, formed in a multilayer construction, comprising:

a liquid crystal display layer positioned to be visible to a user;

a transflective layer positioned behind the liquid crystal display layer;

a photovoltaic layer positioned behind the liquid crystal display layer; and

a circuit layer positioned behind the photovoltaic layer.

15. The optical receiver of claim 14, wherein the transflective layer reflects less than 20% of the incident light.

16. The optical receiver of claim 14, wherein the transflective layer allows at least 50% of the incident light to pass through to the photovoltaic layer.

17. The optical receiver of claim 14, further comprising a radio frequency transmitter.

18. A method of providing product information at the point of product display in an illuminated space comprising:

providing an electronic product tag at the point of product display of at least one product, the electronic product tag comprising;

an optical detector for receiving data from modulated incident light;

a processor operatively coupled to said optical receiver an demodulating the received data;

a display device operatively coupled to the processor for displaying the received data in the form of product information; and

providing said modulated incident light to the optical receiver by providing a common modulating signal to the power supply of each of the illumination sources providing illumination to the space.