Object sensing

• US 20020190964A1
• Filed: 05/22/2002
• Published: 12/19/2002
• Est. Priority Date: 06/14/2001
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Berkel, Cees
• Granted Patent: US 7,286,118 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

An integrated display and object sensing user input device (1) is described. Display components and electric field sensing components are provided on a substrate (12). Also described is a sensing circuit (103) for detecting current induced in a receiving electrode (33) of an electric field sensing arrangement, wherein the sensing circuit (103) employs two-phase charge accumulation. In operation, two effective circuit parts (141, 142) are selected alternately according to the phase of a voltage (120) concurrently causing electric field emission, such that charge is accumulated in the same charge sense during operation of both effective circuit parts (141, 142). Plural thin film electric field sensing circuits and electrodes may be arrayed to provide an object sensing array, usable as an input device (164).

Claims

1. A display and user input device, comprising:

a display substrate comprising a plate and display components formed on the plate; and

an electric field sensing arrangement comprising electric field sensing components, the electric field sensing components comprising one or more electric field transmission electrodes, one or more electric field reception electrodes, and electric field sensing circuit components for driving the electric field transmission electrode or electrodes and sensing induced current in the electric field reception electrode or electrodes;

wherein one or more of the electric field sensing components is formed on the plate.

2. A device according to claim 1, wherein the electric field transmission and reception electrodes are formed on the plate.

3. A device according to claim 2, wherein the display components comprise pixel electrodes, and wherein the electric field transmission electrodes, the electric field reception electrodes and the pixel electrodes are formed on the plate from a same layer of conductor.

5. A device according to claim 3, wherein at least some of the electric field transmission electrodes and the electric field reception electrodes also serve as at least some of the pixel electrodes.

6. A device according to any preceding claim, wherein at least some of the electric field sensing circuit components are formed on the plate.

7. A device according to claim 6, wherein the display components comprise thin film display driving circuit components, and wherein the electric field sensing circuit components and the thin film display driving circuit components are formed on the plate either from at least one shared thin film layer or during at least one shared fabrication process.

8. A device according to any preceding claim, wherein the display components comprise row and column lines and the electric field sensing arrangement is arranged to use the row and/or the column lines.

16. A device according to any of claims 1 to 8, 14 and 15, wherein the electric field sensing circuit components form a sensing circuit according to any of claims 11 to 13.

4. A device according to claim 4, wherein at least some of the electric field transmission electrodes and the electric field reception electrodes are interspersed amongst an array of the pixel electrodes.

9. A method of using a sensing circuit to detect induced current in a receiving electrode of an electric field sensing arrangement, the method comprising:

delivering current induced at the receiving electrode to charge accumulation means of the sensing circuit;

inputting an alternating current drive signal, as supplied to a transmitting electrode of the electric field sensing arrangement, to the sensing circuit; and

using the drive signal to vary operation of the sensing circuit when the drive signal is positive compared to when the drive signal is negative;

wherein the charge accumulation means, the means for delivering induced current, the means for receiving an alternating current drive signal, and the means for using the drive signal to vary operation of the sensing circuit are arranged such that the induced current delivered to the charge accumulation means provides a nett charge at the charge accumulation means, the nett charge being a measure of the current induced in the receiving electrode.

10. A method according to claim 9, wherein:

the step of using the drive signal to vary operation of the sensing circuit when the drive signal is positive compared to when the drive signal is negative comprises using the drive signal to activate a first part of the sensing circuit when the drive signal is positive and using the drive signal to activate a second part of the sensing circuit when the drive signal is negative;

the first part of the sensing circuit delivering, when activated, current induced at the receiving electrode to the charge accumulation means; and

the second part of the sensing circuit delivering, when activated, current induced at the receiving electrode to the charge accumulation means;

the first part of the sensing circuit, the second part of the sensing circuit, and the charge accumulation means being arranged such that the induced current delivered by each of the first and second parts of the sensing circuit is delivered to the charge accumulation means with the same charge sense.

11. A sensing circuit for detecting induced current in a receiving electrode of an electric field sensing arrangement, the sensing circuit comprising:

a charge accumulation means;

means for delivering current induced at the receiving electrode to the charge accumulation means;

means for receiving an alternating current drive signal, as supplied to a transmitting electrode of the electric field sensing arrangement; and

means for using the drive signal to vary operation of the sensing circuit when the drive signal is positive compared to when the drive signal is negative;

wherein the charge accumulation means, the means for delivering induced current, the means for receiving an alternating current drive signal, and the means for using the drive signal to vary operation of the sensing circuit are arranged such that in operation the induced current is delivered to the charge accumulation means such as to provide a nett charge at the charge accumulation means, the nett charge being a measure of the current induced in the receiving electrode.

12. A sensing circuit according to claim 11, wherein:

the means for using the drive signal to vary operation of the sensing circuit when the drive signal is positive compared to when the drive signal is negative comprises means for using the drive signal to activate a first part of the sensing circuit when the drive signal is positive and means for using the drive signal to activate a second part of the sensing circuit when the drive signal is negative;

the first part of the sensing circuit comprising means for delivering, when activated, current induced at the receiving electrode to the charge accumulation means; and

the second part of the sensing circuit comprising means for delivering, when activated, current induced at the receiving electrode to the charge accumulation means;

the first part of the sensing circuit, the second part of the sensing circuit, and the charge accumulation means being arranged such that in operation the induced current delivered by each of the first and second parts of the sensing circuit is delivered to the charge accumulation means with the same charge sense.

13. A sensing circuit according to claim 12, wherein:

the sensing circuit comprises a first n-type transistor, a second n-type transistor, a first p-type transistor, a second p-type transistor, and the accumulation means;

the accumulation means comprises a capacitor;

the gates of the transistors are connected to each other and to the means for receiving an alternating current drive signal;

a first terminal of the first n-type transistor and a first terminal of the second p-type transistor are connected to each other and to the electric field sensing reception electrode;

a second terminal of the first n-type transistor and a first terminal of the first p-type transistor are connected to each other and to a first side of the capacitor;

a second terminal of the first p-type transistor and a second terminal of the second n-type transistor are connected to each other and to a further line; and

a second terminal of the second p-type transistor and a first terminal of the second n-type transistor are connected to each other and to the second side of the capacitor;

such that the first part of the sensing circuit comprises the first n-type transistor, the capacitor and the second n-type transistor; and

the second circuit part of the sensing circuit comprises the first p-type transistor, the capacitor, and the second p-type transistor.

15. A device according to claim 14, wherein the electric field transmission electrodes and the electric field reception electrode are arranged on the plate in a two-dimensional array.

14. An electric field sensing device, comprising:

a plate;

a plurality of electric field transmission electrodes formed on the plate;

a plurality of electric field reception electrodes formed on the plate; and

electric field sensing circuit components, for driving the plurality of electric field transmission electrodes and sensing currents induced in the plurality of electric field reception electrodes, formed from thin film layers on the plate.