Fail safe display for shelf labels

• US 5,160,920 A
• Filed: 12/07/1990
• Issued: 11/03/1992
• Est. Priority Date: 12/07/1990
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Harris, Richard H.
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): HJERPE, RICHARD A
• Application Number:
  US07/623,847
• Time in Patent Office: 697 Days
• Field of Search: 340/765, 340/784, 340/716, 340/717, 340/825.73, 340/715, 340/794, 340/796, 340/797, 340/795, 359/36, 136/244, 136/252, 136/256
• US Class Current: 345/52
• CPC Class Codes: G06F 11/0796 Safety measures, i.e. ensuring safe condition in the event of error, e.g. for controlling element
• CPC Class Codes: G09G 2330/10 Dealing with defective pixels
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/18 using liquid crystals
• CPC Class Codes: Y10S 345/904 Display with fail/safe testing feature

Abstract

Described is an electronic shelf label LCD device having a segmented liquid crystal (LC) film disposed on a plurality of segmented and non-segmented photovoltaic cells which provide power for driving the LCD device and electrical signals which are used to indicate malfunctioning LCD segments.

Claims

1. A device for displaying information comprising:

a liquid-crystal display (LCD) means, said display means carrying a plurality of display segments which are grouped to form desired shapes and/or alphanumeric characters;

a support means coupled to the LCD means, said support means providing photovoltaic conversion from light passing through said LCD means and having a plurality of photovoltaic segments thereon, with said segments being arranged into shapes and/or alphanumeric characters which are similar to those on the LCD means; and

control means coupled to the liquid crystal display (LCD) means and the support means;

said control means monitoring the support means to detect electrical signals generated as a result of light transmitted through the liquid crystal display means and using said electrical signals to generate error signals representative of malfunctioning display segments.

2. The device of claim 1 further including a printed circuit board for supporting components of claim 1;

said circuit board receiving electrical power from the support means.

3. The device of claim 2 further including a housing having a back cover and a front cover, with a window section to view the display segment, for encasing the printed circuit board, the support means and the liquid crystal display means.

4. The device of claim 1 wherein the support means includes a plurality of photovoltaic cells;

a plurality of photovoltaic lead, one of each connected to selected ones of the plurality of photovoltaic cells; and

a common photovoltaic lead connected to selected ones of the plurality of photovoltaic cells.

5. The device of claim 1 wherein the liquid-crystal display means includes a liquid-crystal film.

6. The device of claim 1 wherein the LCD includes a nematic liquid trapped between conductor-carrying support members.

7. The device of claim 1 wherein the control means includes a controller;

a display driver means generating drive signals which energize the display segments in response to control signals outputted by the controller;

a first circuit means for generating output signals representative of voltages generated by selected ones of the photovoltaic segments; and

a second circuit means for correlating selected ones of the drive signals with selected ones of the output signals to generate the error signals.

8. The device of claim 7 wherein the controller includes a microprocessor.

9. The device of claim 7 wherein the first circuit means includes comparator circuits.

10. The device of claim 7 wherein the second circuit means includes EX OR circuits.

11. An improved electronic shelf label system comprising:

a display subsystem;

said display subsystem having a liquid crystal display means on which at least one multisegment alphanumeric character is formed;

at least a first photovoltaic cell positioned to receive light transmitted through at least one segment of the multi-segment alphanumeric character and to generate at least a first electrical signal therefrom;

at least a second photovoltaic cell positioned to receive light transmitted through non-segmented areas of said display subsystem and to generate and output a second electrical signal representative of said light;

a first circuit means for generating and applying electrical drive signals to selected segments of said multi-segment alphanumeric character;

a second circuit means for correlating the first electrical signal with the second electrical signal to generate and output a resultant signal; and

a third circuit means responsive to the electrical drive signals and the resultant signal to generate an error signal representative of malfunctioning segments.

12. The improved electronic shelf label of claim 11 wherein the liquid crystal display means includes liquid crystal film.

13. The improved electronic shelf label system of claim 12 wherein the first means includes a display driver circuit.

14. The improved electronic shelf label system of claim 13 wherein the second circuit means includes a comparator circuit.

15. The improved electronic shelf label system of claim 14 wherein the third circuit means includes an EX OR circuit.