Optical navigation systems and methods for background light detection and avoiding false detection and auto-movement

• US 9,927,915 B2
• Filed: 09/18/2015
• Issued: 03/27/2018
• Est. Priority Date: 09/26/2014
• Status: Active Grant

• Current Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Frame, John, Mu, Jing
• Primary Examiner(s): Lubit, Ryan A
• Application Number:
  US14/858,217
• Publication Number:
  US 20160117048A1
• Time in Patent Office: 921 Days
• Field of Search: None
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• 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 3/044 by capacitive means
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method of operating an optical navigation system which includes disabling a light source to measure the ambient or external light level, comparing the measurement to a threshold level to determine whether the ambient light would cause false detection and light induced motion, and adjusting sensing parameter(s) to mitigate the effect of the ambient light.

Claims

1. A method, comprising:

disabling and enabling, using at least one processing element, a light source in an optical navigation sensor (ONS) periodically;

using the at least one processing element, receiving a first plurality of signals from sampling by an optical detector of the ONS during a first time corresponding to the light source being disabled, wherein a periodicity of the sampling by the optical detector is jittered;

receiving, using the at least one processing element, from the optical detector a second plurality of signals during a second time corresponding to the light source being enabled;

comparing at least one of the first plurality of signals to a threshold value; and

in response to the at least one of the first plurality of signals being greater than the threshold value, suppressing, using the at least one processing element, reporting of the second plurality of signals to avoid false detection and auto-movement in an output of the ONS.

2. The method of claim 1, wherein the first plurality of signals corresponds to external light to the ONS propagated upon the optical detector.

3. The method of claim 2, wherein the ONS is disposed in a vehicle and the external light comprises sunlight.

4. The method of claim 2, wherein the second plurality of signals corresponds to both the external light and light reflected or scattered off a tracking surface, propagated upon the optical detector.

5. The method of claim 4, further comprising:

in response to the at least one of the first plurality of signals being less than the threshold value, reporting the second plurality of signals to derive motion data of the tracking surface.

6. The method of claim 1, further comprising:

comparing multiple signals of the first plurality of signals to the threshold value; and

in response to at least one of the multiple signals of the first plurality of signals being greater than the threshold value, suppressing reporting of the second plurality of optical signals.

7. The method of claim 1, further comprising:

deriving an average value based on the first plurality of signals;

comparing the average value to the threshold value; and

in response to the average value being greater than the threshold value, suppressing reporting of the second plurality of optical signals.

8. The method of claim 1, further comprising:

controlling, using the at least one processing element, a first time schedule of the disabling and enabling the light source, and a second time schedule of the receiving of the first and the second plurality of signals; and

synchronizing, using the at least one processing element, the first and the second time schedules whereby the first plurality of signals corresponds to a time period the light source is disabled and the second plurality of signals corresponds to a time period the light source is enabled.

9. The method of claim 8, further comprising:

incorporating a time delay period preceding the first time period to mitigate effects of a moving external light source on a fixed time schedule, wherein a duration of the time delay period is random.

10. The method of claim 1, wherein the periodicity of the sampling is littered based on random intervals.

11. The method of claim 1, wherein the comprises periodicity of the sampling is jittered based on pseudo-random intervals.

12. A method, comprising:

enabling and disabling a light source, using at least one processing element, in an optical navigation sensor (ONS);

using the at least one processing element, receiving a first plurality of PD signal samples from sampling by a photo-diode (PD) array in the ONS during a first time period corresponding to the light source being disabled and a second plurality of PD signal samples from sampling by the PD array during a second time period corresponding to the light source being enabled, wherein a periodicity of the sampling by the PD array is jittered;

comparing the first plurality of PD signal samples to at least one threshold value; and

in response to an outcome of the comparing the first plurality of PD signal samples to the at least one threshold value, adjusting, using the at least one processing element, at least one sensing parameter of the ONS, to mitigate effects of external light to the ONS on the second plurality of PD signal samples, wherein the first plurality of PD signal samples is collected before the second plurality of PD signal samples.

13. The method of claim 12, wherein the ONS is disposed within a vehicle as a part of an input system and the external light comprises sunlight.

14. The method of claim 12, wherein the sensing parameters comprise an output level of the light source, the timing schedule, and a size of the second plurality of PD signal samples being reported.

15. The method of claim 12, wherein the second plurality of PO signal samples comprises signals induced by both the external light and light reflected or scattered off a tracking surface, incident on the PD array.

16. The method of claim 14, further comprising:

in response to the first plurality of PD signal samples being less than the at least one threshold value, deriving motion data of the tracking surface from the second plurality of PD signal samples.

17. The method of claim 12, wherein the at least one threshold value is predetermined and stored in the at least one processing element and is programmable or adaptable according to the at least one sensing parameter of the ONS.

18. An input system disposed within a vehicle, the input system comprising:

an optical navigation sensor (ONS) and a top panel, wherein the ONS detects and tracks motion of a tracking surface placed onto the top panel, the ONS comprising;

a light source configured to illuminate the tracking surface, wherein output level of the light source is switched between a low level and a high level,

a photo-diode (PD) array configured to receive light incident thereon and generate PD signal samples based on periodically sampling the light received, wherein the light received comprises light reflected or scattered off the tracking surface and external light to the input system, wherein a periodicity of the sampling by the PD array is jittered, and

a processing element configured to;

control the output level switching of the light source based a timing schedule,

collect the PD signal samples from the PD array,

compare the PD signal samples, collected during a first period corresponding to the output level being at the low level, to a threshold value to determine if the external light exceeds a predetermined level,

in response to determining the external light does not exceed the predetermined level, report the PD signal samples collected during at least one subsequent period to the first period corresponding to the output level being at the high level, and

derive motion data of the tracking surface from the reported PD signal samples.

19. The input system of claim 18, wherein the light source, the photo-diode (PD) array and the processing element are formed in a single integrated circuit package;

and

the PD array comprises a first plurality of photo-diodes and a second plurality of photo-diodes disposed adjacent to one another, wherein the PD signal samples generated by the first plurality of photo-diodes are collected in response to the light source being at the low level, and the PD signal samples generated by the second plurality of photo-diodes are collected in response to the light source being at the high level.

20. The input system of claim 18, further comprising:

a capacitive sense element, disposed onto the top panel of the input system and coupled to a capacitance sensor, wherein the capacitance sensor is configured to determine presence of the tracking surface on the top panel.