Electronic Device Display With Monitoring Circuitry

• US 20180053466A1
• Filed: 09/23/2016
• Published: 02/22/2018
• Est. Priority Date: 08/19/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zhang, Rui, Hajirostam, Mohammad, Lin, Hung Sheng, Vahid Far, Mohammad B., Youn, Sang Y., Zhang, Zhen, Mandlik, Prashant, Chang, Sun-Il, Ryu, Jie Won, Gao, Shengkui, Nho, Hyunwoo, Yao, Wei H., Bi, Yafei, Wang, Yun
• Granted Patent: US 10,643,511 B2
• Time in Patent Office: Days
• CPC Class Codes: G01L 1/2281 for temperature variations
• CPC Class Codes: G01M 5/0033 by determining damage, crack or wear
• CPC Class Codes: G01M 5/0083 by measuring variation of impedance, e.g. resistance, capacitance, induction
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• 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 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/035 for flexible display surfaces
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G11C 19/28 using semiconductor elements G11C19/14, G11C19/36 take precedence
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 77/111 Flexible substrates
• CPC Class Codes: Y02E 10/549 Organic PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

An electronic device may have a flexible display such as an organic light-emitting diode display. A strain sensing resistor may be formed on a bent tail portion of the flexible display to gather strain measurements. Resistance measurement circuitry in a display driver integrated circuit may make resistance measurements on the strain sensing resistor and a temperature compensation resistor to measure strain. A crack detection line may be formed from an elongated pair of traces that are coupled at their ends to form a loop. The crack detection line may run along a peripheral edge of the flexible display. Crack detection circuitry may monitor the resistance of the crack detection line to detect cracks. The crack detection circuitry may include switches that adjust the length of the crack detection line and thereby allow resistances to be measured for different segments of the line.

Claims

1. A display system, comprising:

a flexible display having an array of pixels;

a crack detection resistor that runs along a peripheral edge of the flexible display, wherein the crack detection resistor has first and second parallel lines that are coupled to form a loop and wherein the display comprises a plurality of switches each of which is coupled to the first and second parallel lines at a different respective location along the first and second parallel lines; and

a display driver integrated circuit that supplies data to columns of the pixels over data lines;

gate driver circuitry that supplies control signals to rows of the pixels over gate lines, wherein the switches form part of the gate driver circuitry; and

resistance measurement circuitry in the display driver integrated circuit that is configured to control the switches to make resistance measurements on the crack detection resistor to detect cracks in the crack detection line.

2. The display system defined in claim 1 wherein the gate driver circuitry includes a shift register with a chain of register circuits and wherein each of the switches forms part of a respective one of the register circuits.

3. The display system defined in claim 2 wherein the resistance measurement circuitry comprises:

an integrator that integrates current from the crack detection resistor; and

a comparator that compares output signals from the integrator to a reference voltage;

a counter; and

control logic that makes the resistance measurements at least partly by obtaining a count value from the counter in response to detection of a change in state of an output from the comparator.

4. The display system defined in claim 3 further comprising:

a reference resistor; and

a selection switch coupled between a reference voltage source and a selected one of;

the reference resistor and the crack detection resistor.

5. The display system defined in claim 1 further comprises a flexible printed circuit that is coupled to flexible display, wherein the display driver integrated circuit is mounted to the flexible printed circuit.

6. The display system defined in claim 5 further comprising test pads on the flexible printed circuit that are configured to couple to probes from a test system.

7. The display system defined in claim 1 wherein the resistance measurement circuit comprises:

an integrator;

at least one reference resistor; and

at least one selection switch configured to couple a selected one of the reference resistor and the crack detection resistor to the integrator.

8. The display system defined in claim 7 wherein the resistance measurement circuit further comprises:

a comparator that receives output signals from the integrator;

a counter; and

control logic configured to obtain a count value from the counter in response to detection of a change in state of an output of the comparator.

9. A display system, comprising:

a flexible display having an array of pixels;

a display driver integrated circuit that supplies data to columns of the pixels over data lines;

gate driver circuitry that supplies control signals to rows of the pixels over gate lines;

a crack detection line that runs along a peripheral edge of the flexible display; and

resistance measurement circuitry in the display driver integrated circuit that is configured to make resistance measurements on the crack detection line to detect cracks in the crack detection line.

10. The display system defined in claim 9 wherein the crack detection line comprises first and second parallel traces that run along the peripheral edge of the flexible display and that have ends that are coupled by a connection path.

11. The display system defined in claim 10 further comprising a plurality of switches each of which is coupled between the first and second parallel traces at a different respective location along the first and second parallel traces.

12. The display system defined in claim 11 wherein the gate driver circuitry includes a shift register with a chain of register circuits and wherein each of the switches forms part of a respective one of the register circuits.

13. The display system defined in claim 11 wherein at least some of the switches form part of the gate driver circuitry.

14. The display system defined in claim 9 wherein the resistance measurement circuitry comprises:

an integrator;

at least one reference resistor; and

at least one selection switch configured to cause current from a selected one of the reference resistor and the crack detection resistor to pass to the integrator.

15. The display system defined in claim 14 wherein the resistance measurement circuitry further comprises:

a comparator that receives output signals from the integrator;

a counter; and

control logic configured to obtain a count value from the counter in response to detection of a change in state of an output of the comparator.

16. The display system defined in claim 15 wherein the control logic is configured to obtain a first count value associated with integrating current with the integrator that passes through the reference resistor and a second count value associated with integrating current with the integrator that passes through the crack detection resistor.

17. A display system, comprising:

a display having pixels;

gate driver circuitry that supplies control signals to the pixels;

a crack detection line that forms a loop running along a peripheral edge of the display; and

a display driver integrated circuit that supplies data to the pixels over data lines and that includes resistance measurement circuitry that is configured to make resistance measurements on the crack detection line.

18. The display system defined in claim 17 further comprising switches in the gate driver circuitry that are coupled to the crack detection line.

19. The display system defined in claim 18 wherein the crack detection line comprises first and second parallel traces that run along the peripheral edge of the display and that have ends that are coupled by a connection path and wherein each of the switches is coupled between the first and second parallel traces at a different respective location along the first and second parallel traces.

20. The display system defined in claim 19 wherein the resistance measurement circuitry includes an integrator that integrates current passing through the crack detection line.