ASIC CONTROLLER FOR LIGHT-BASED TOUCH SCREEN

• US 20120188205A1
• Filed: 03/20/2012
• Published: 07/26/2012
• Est. Priority Date: 11/02/2001
• Status: Active Grant

• Current Assignee: Neonode, Inc.
• Original Assignee: Neonode, Inc.
• Inventors: Jansson, Anders, Goertz, Magnus, Eriksson, Thomas, Shain, Joseph, Kvist, Niklas, Pettersson, Robert, Sparf, Lars, Karlsson, John
• Granted Patent: US 8,674,966 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

A controller including a chip package coupled with a light-based touch screen, emitter driver circuitry inside the chip package for selectively activating photoemitters that are outside of the chip package, detector driver circuitry inside the chip package for selectively activating photo detectors that are outside of the chip package, detector signal processing circuitry for generating detection signals representing amounts of light detected on the photo detectors, signal conducting pins for connecting the photoemitters to the emitter driver circuitry, signal conducting pins for connecting the photo detectors to the detector driver circuitry and to the detector signal processing circuitry, controller circuitry inside the chip package for controlling the emitter driver circuitry and the detector driver circuitry, and at least one input/output pin for outputting the detection signals to a host processor, for the host processor to identify one or more locations on the touch screen that are being touched.

Claims

1. A controller for a light-based touch screen comprising:

a chip package coupled with a light-based touch screen;

emitter driver circuitry inside said chip package for selectively activating a plurality of photoemitters that are outside of said chip package;

detector driver circuitry inside said chip package for selectively activating a plurality of photo detectors that are outside of said chip package;

detector signal processing circuitry for generating detection signals representing measured amounts of light detected on the plurality of photo detectors;

a first plurality of signal conducting pins for connecting the plurality of photoemitters outside the chip package to said emitter driver circuitry inside the chip package;

a second plurality of signal conducting pins for connecting the plurality of photo detectors outside the chip package to said detector driver circuitry and to said detector signal processing circuitry inside the chip package;

controller circuitry inside said chip package for controlling said emitter driver circuitry and said detector driver circuitry; and

at least one input/output pin for communicating with a host processor and for outputting the detection signals generated by said detector signal processing circuitry to the host processor, for the host processor to identify one or more locations on the touch screen that are being touched.

2. The controller of claim 1, wherein said controller circuitry comprises programmable registers for configuring a scan pattern whereby each of said plurality of photoemitters is paired with one or more of said plurality of photo detectors, and each of said plurality of photo detectors is paired with one or more of said plurality of photoemitters.

3. The controller of claim 2, wherein said plurality of photoemitters and photo detectors are arranged to respectively emit and detect two sets of overlapping wide light beams, and wherein said controller circuitry is configurable to generate a scan sequence of one set of the wide light beams to detect an initial touch, and to generate a scan sequence of both sets of the wide light beams after detecting the initial touch.

4. The controller of claim 3, wherein the photoemitters and photo detectors are activated so as to respectively emit and detect the two sets of overlapping wide light beams in 1 millisecond or less, to provide substantially concurrent detections along horizontal and vertical touch screen axes.

5. The controller of claim 4, wherein the photoemitters and photo detectors are activated so as to respectively emit and detect the two sets of overlapping wide light beams at a rate of at least 50 Hz, to detect an initial touch location of a first of two fingers when a user places two fingers on the touch screen, and wherein the host processor detects the second touch location of the two fingers based on the initial touch location.

6. The controller of claim 4 further comprising:

an analog-to-digital controller (ADC);

an amplifier; and

a digital controller core,

wherein the photoemitters and photo detectors are activated so as to respectively emit and detect the two sets of overlapping wide light beams at a rate of at least 100 Hz, and wherein the controller consumes less than 2 milliwatts of power by selectively activating said ADC, said amplifier, and said digital controller core only when needed.

7. The controller of claim 4, wherein the photoemitters and photo detectors are activated so as to respectively emit and detect the two sets of overlapping wide light beams at a rate of at least 500 Hz, wherein the host processor updates the identified touch locations at a rate of 100 Hz or less, and wherein the host enhances the signal-to-noise ratio based on statistics of on multiple activations for each identified touch location.

8. The controller of claim 7, wherein the controller consumes less than 20 milliwatts of power.

9. The controller of claim 2, wherein said plurality of photoemitters and photo detectors are arranged to respectively emit and detect two sets of overlapping wide light beams, and wherein said controller circuitry is configurable to generate an alternating scan sequence of both sets of the wide light beams to detect an initial touch.

10. The controller of claim 2, wherein said plurality of photoemitters and photo detectors are arranged to respectively emit and detect two sets of overlapping wide light beams along each of four axes, and wherein said controller circuitry is configurable to generate a scan sequence of both sets of wide light beams on the four axes.

11. The controller of claim 2, wherein said emitter driver circuitry comprises:

a plurality of registers for storing individual photoemitter pulse duration values for a corresponding plurality of emitter-detector pairs; and

circuitry for generating the photoemitter pulses in accordance with the stored pulse duration values.

12. The controller of claim 2, wherein said emitter driver circuitry comprises:

a plurality of registers for storing individual photoemitter pulse current values for a corresponding plurality of emitter-detector pairs; and

circuitry for generating the photoemitter pulses in accordance with the stored pulse current values.

13. The controller of claim 12, wherein said circuitry for generating the photoemitter pulses comprises a programmable current source, for driving the photoemitters.

14. The controller of claim 1, wherein said detector signal processing circuitry comprises circuitry for filtering current received from the photo detectors.

15. The controller of claim 14, wherein said circuitry for filtering current comprises circuitry to perform a continuous feedback bandpass filter.

16. The controller of claim 15, wherein said detector signal processing circuitry comprises circuitry to digitize the bandpass filtered current.

17. The controller of claim 16, wherein said controller circuitry subtracts a first digitized current value representing an ambient light value from a second digitized current value representing light detected during activation of a photoemitter.

18. The controller of claim 1, wherein said controller circuitry comprises circuitry for activating the photoemitters and the photo detectors in order according to a user-defined sequence.

19. The controller of claim 1, wherein said controller circuitry comprises circuitry for selecting a user-defined subset of the plurality of photoemitters and a user-defined subset of the plurality of photo detectors and for activating the selected photoemitters and the selected photo detectors in order according to a user-defined sequence.

20. A touch screen system, comprising:

a housing;

a surface mounted on said housing;

a host processor mounted in said housing, for determining touch locations on said surface;

a plurality of light emitters for emitting light that is transmitted over said surface;

a plurality of light receivers for producing output values based on detected light emitted by said emitters; and

first and second controllers according to claim 1 connected to said host processor, to said emitters and to said receivers, for receiving scan configuration settings from said host processor, for activating said emitters in a substantially uninterrupted scan sequence in accordance with the scan configuration settings, and for storing output values from said receivers,

wherein the numbers of said light emitters and said light receivers are greater than the respective numbers of light emitters and light receivers supported by the signal conducting pins of each of said first and second controllers.

21. The touch screen system of claim 20 wherein a first emitter is connected to said first controller and a second emitter is connected to said second controller, wherein light from the first emitter and light from the second emitter is detected by a receiver that is connected to both of said controllers, and wherein the receiver output values for detected light emitted by the first emitter are stored by said first controller and the receiver output values for detected light emitted by the second emitter are stored by said second controller.