Self-powered Electronic Label

• US 20120000974A1
• Filed: 06/30/2010
• Published: 01/05/2012
• Est. Priority Date: 06/30/2010
• Status: Active Grant

• Current Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Original Assignee: Hong Kong Applied Science And Technology Research Institute Co., Ltd.
• Inventors: HUNG, Wai, LU, Ming
• Granted Patent: US 8,261,971 B2
• Time in Patent Office: Days
• US Class Current: 235/375
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G09G 2330/023 using energy recovery or conservation
• CPC Class Codes: G09G 2370/18 Use of optical transmission of display information
• CPC Class Codes: G09G 2380/04 Electronic labels
• CPC Class Codes: G09G 2380/14 Electronic books and readers

Abstract

An electronic label system is provided which includes a data source having information to be displayed by an electronic label. An optical source such as an LED array broadcasts optical signals modulated with the data source data to plural electronic labels. Each electronic label has an optical receiver which receives the modulated optical signals and also receives unmodulated optical signals to supply power to an energy storage device. A mode switch switches the optical receiver between a signal reception mode and an energy storage device power-supplying mode. One or more bistable displays display the data received from the modulated optical signals. Through the use of bistable displays, the power consumption of the electronic label is greatly reduced while use of a single receiving element for receiving both the signal light and power storage light reduces the number of components needed to assemble the electronic label, thus reducing cost.

Claims

1. An electronic label system comprising:

a data source including information to be displayed by an electronic label;

an LED array for broadcasting optical signals to a plurality of the electronic labels;

a modulator for modulating the optical signals broadcast by the LED array with data from the data source;

the electronic label comprising an optical receiver for receiving the modulated optical signals broadcast by the LED array and for receiving unmodulated optical signals for supplying power to an energy storage device, a mode switch for switching the optical receiver between a modulated optical signal receiving mode and an energy storage device power-supplying mode, and one or more bistable displays for displaying the data received from the modulated optical signals, the bistable display continuously displaying a set of data without the need for a display-maintaining electric field until receipt of a new modulated optical signal causes new data to be displayed.

2. An electronic label system according to claim 1 wherein the LED array comprises a plurality of LEDs of different colors including at least red, green and blue LEDs, and further comprising a controller for controlling the LEDs to generate a wavelength division multiplexed optical signal.

3. An electronic label system according to claim 2 wherein the optical receiver includes an optical filter covering at least a portion of a surface of the optical receiver, the filter being configured to receive light of a single wavelength from the wavelength division multiplexed optical signal.

4. An electronic label system according to claim 2 wherein the optical receiver includes plural optical filters covering at least a portion of a surface of the optical receiver, each of the plural filters being configured to receive light of a single wavelength from the wavelength division multiplexed optical signal.

5. An electronic label system according to claim 1 wherein the optical receiver comprises a multi-segment photovoltaic device in which plural segments are dedicated to power-supply to the energy storage device and plural segments are switched between a modulated optical signal receiving mode and an energy storage device power-supplying mode.

6. An electronic label system according to claim 1 wherein the wavelength of the optical signal is one or more wavelengths in a range from 450 nm to 900 nm.

7. An electronic label system according to claim 2 including a plurality of electronic labels, a subset of the plurality of electronic labels each including an optical filter covering at least a portion of the optical receiver such that a given subset of electronic labels is configured to receive only one wavelength of light from the wavelength division multiplexed optical signal.

8. An electronic label system according to claim 1 wherein the bistable display is selected from electronic paper, ferroelectric liquid crystal displays, chiral nematic liquid crystal displays, cholesteric liquid crystal displays, gyricon particle displays, magnetic material-based displays, electronic ink displays, electrophoretic displays, or electrochromic displays.

9. An electronic label system according to claim 1 wherein the LEDs are selected from an array of LEDs.

10. An electronic label system according to claim 1 wherein the optical receiver is a photovoltaic device.

11. An electronic label system according to claim 1 further comprising a demodulator and a processor.

12. An electronic label system according to claim 11 further comprising a bistable display driver.

13. An electronic label system according to claim 1 further comprising a power management device communicating with the energy storage device and the bistable display.

14. An electronic label system according to claim 1 wherein the optical receiver comprises a multi-segment photovoltaic device in which plural segments are dedicated to power-supply to the energy storage device and plural segments are dedicated to a modulated optical signal receiving mode.

15. A method for updating information on an electronic label using the electronic label system of claim 1 comprising emitting a modulated optical signal from the LED array, receiving the modulated optical signal and updating information displayed on a bistable display and maintaining the information displayed on the bistable display until another modulated optical signal is received from the LED array containing new information to be displayed.

16. A method for sending a modulated WDM optical signal to a plurality of electronic labels using the electronic label system of claim 2 comprising sequentially flashing the red, green, and blue LEDs sequentially for periods of time such that the human eye perceives emitted light as being white light.

17. A method for sending a modulated WDM optical signal to a plurality of electronic labels using the electronic label system of claim 2 comprising sequentially flashing the red, green, and blue LEDs simultaneously for periods of time such that the human eye perceives emitted light as being white light.