Display device with electrostatic discharge protection circuitry

• US 7,453,420 B2
• Filed: 02/06/2004
• Issued: 11/18/2008
• Est. Priority Date: 02/14/2003
• Status: Expired due to Fees

• Current Assignee: Innolux Hong Kong Holding Ltd (InnoLux Corporation)
• Original Assignee: TPO Hong Kong Holding Limited (InnoLux Corporation)
• Inventors: Inada, Toshiya, Watanabe, Hidetoshi
• Primary Examiner(s): Shankar; Vijay
• Application Number:
  US10/545,465
• Publication Number:
  US 20060145951A1
• Time in Patent Office: 1,747 Days
• Field of Search: 345 50- 55, 345 87-104, 345204-215, 345690-699, 257/59, 257/360
• US Class Current: 345/55
• CPC Class Codes: G02F 1/136204 Arrangements to prevent high voltage or static electricity failures
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/04 Display protection
• CPC Class Codes: G09G 2330/08 Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared
• 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

Abstract

An object of the invention is to provide electrostatic discharge damage protection during manufacturing and to suppress power consumption as low as possible during ordinary use of the electronic device having been manufactured, with avoidance of the problem of electric corrosion. An electronic device 10 comprising an array of pixels 12 wherein row and column address lines 18, 20 for addressing each pixel 12 are arranged. Each address line is connected to a discharge line 30, 32 through a discharge 38. The circuit allows the passage of charge between the address line and the first discharge line 30 when the address line is at a potential below that of the first discharge line, and allows the passage of charge between the address line and the second discharge line 32 when the address line is at a potential above that of the second discharge line. The discharge elements have a configuration in which the one is in an electrically floating state during ordinary operation of the electronic device, or a conductive path making conduction in order that leakage current of the discharge device occurring during ordinary operation of the electronic device can be used for the peripheral circuitry.

Claims

1. An electronic device comprising:

an array of pixels provided on a substrate and arranged in rows and columns, each pixel comprising a switch element; and

a plurality of row and column address lines for addressing each pixel,

wherein;

each row and column address line is connected to a first discharge element through a first discharge device and to a second discharge element through a second discharge device, and electrical isolation/conduction means are provided between the first and second discharge elements,

the first discharge device provides a unidirectional current path that allows the passage of charge between the address line and the first discharge element when the address line is at a potential below that of the first discharge element, and the second discharge device provides a unidirectional current path that allows the passage of charge between the address line and the second discharge element when the address line is at a potential above that of the second discharge element,

the electrical isolation/conduction means electrically isolating the first discharge element from the second discharge element after mounting peripheral circuitry and/or during ordinary operation of the electronic device, while allowing the passage of charge between the first and second discharge elements before completion of the mounting of peripheral circuitry and/or except during said ordinary operation, and

at least one of the first and second discharge elements has a configuration in which the one is in a substantially electrically floating state during ordinary operation of the electronic device.

2. The device of claim 1, wherein the electrical isolation/conduction means comprise a switching element that is turned off and provides a high impedance between the first and second discharge elements after mounting peripheral circuitry and/or during ordinary operation of the electronic device, while being turned on and allowing conduction between the first and second discharge elements before completion of the mounting of peripheral circuitry and/or except during said ordinary operation.

3. The device of claim 2, wherein the switching element is constituted by a transistor comprising:

two input/output electrodes connected to the first and second discharge elements, respectively; and

a control electrode, and the electrical isolation/conduction means further comprises;

a resistance element coupling the control electrode with one of the input/out electrodes or the second discharge element; and

a circuit section arranged to apply the control electrode with a voltage for turning on the transistor via the resistance element on the basis of a voltage occurring between the first and second discharge elements before completion of mounting peripheral circuitry and/or except ordinary operation of the electronic device, and on the other hand, to apply the control electrode with a voltage for turning off the transistor after mounting peripheral circuitry and/or during said ordinary operation.

4. The device of claim 3, wherein the circuit section includes a coupling portion for short-circuiting between the control electrode and the first or the second discharge element during said ordinary operation.

5. An electronic device comprising:

an array of pixels provided on a substrate and arranged in rows and columns, each pixel comprising a switch element; and

a plurality of row and column address lines for addressing each pixel,

wherein;

each row and column address line is connected to a first discharge element through a first discharge device and to a second discharge element through a second discharge device,

the first discharge device provides a unidirectional current path that allows the passage of charge between the address line and the first discharge element when the address line is at a potential below that of the first discharge element, and the second discharge device provides a unidirectional current path that allows the passage of charge between the address line and the second discharge element when the address line is at a potential above that of the second discharge element,

the first and second discharge elements are initially short-circuited, and the connection between the first and second discharge elements is broken down before the operation of the electronic device, and

at least one of the first and second discharge elements has a configuration in which the one is in a substantially electrically floating state during ordinary operation of the electronic device.

6. The device of claim 5, wherein the first discharge element includes one or more conductive tracks to which the row and column address lines are connected through their respective first discharge devices, the conductive tracks being arranged in the vicinity of the periphery of the pixel array.

7. The device of claim 5, wherein the second discharge element includes one or more conductive tracks to which the row and column address lines are connected through their respective second discharge devices, the conductive tracks being arranged in the vicinity of the periphery of the pixel array.

8. The device of claim 6, wherein the conductive track is extended surrounding the periphery of the pixel array.

9. The device of claim 5, wherein each discharge device includes at least one unidirectionally conductive element.

12. The device of claim 5, wherein at least one conductive line other than the row and column address lines is also connected to the first or second discharge element through the first discharge device.

13. The device of claim 5, wherein at least one of the first and second discharge elements is coupled to a power supply line for a driver circuit of the pixel array in order that leakage current of the discharge device occurring during operation of the electronic device can be used for peripheral circuitry of the pixel array.

14. The device of claim 6, wherein each of the first and second discharge element includes one or more conductive tracks to which the row and column address lines are connected through their respective first and second discharge devices, the conductive tracks being arranged in the vicinity of the periphery of the pixel array.

15. The device of claim 14, wherein the conductive tracks are extended surrounding the periphery of the pixel array.

10. An electronic device comprising:

an array of pixels provided on a substrate and arranged in rows and columns, each pixel comprising a switching element; and

a plurality of row and column address lines for addressing each pixel,

wherein

each row and column address line is connected to a first discharge element through a first discharge device and to a second discharge element through a second discharge device,

wherein the first discharge device allows the passage of charge between the address line and the first discharge element when the address line is at a potential below that of the first discharge element, and the second discharge device allows the passage of charge between the address line and the second discharge element when the address line is at a potential above that of the second discharge element,

wherein at least one of the first and second discharge elements has a conductive path making conduction in order that leakage current of the discharge device occurring during ordinary operation of the electronic device can be used for peripheral circuitry of the pixel array.

11. The device of claim 10, wherein the conductive path connects the second discharge element and a power supply line for a driver circuit for applying signals to the column address lines.

16. The device of claim 10, wherein the second discharge element includes one or more conductive tracks to which the row and column address lines are connected through their respective second discharge devices, the conductive tracks being arranged in the vicinity of the periphery of the pixel array.

17. The device of claim 10, wherein the first and second discharge devices each provides a unidirectional current path.

18. The device of claim 10, wherein the conductive path is connected to a power supply line for a driver circuit of the pixel array.