Automatic optimisation of touch signal

Abstract

A method of operating an optical touch apparatus is described wherein, the optical touch apparatus comprising a panel, a plurality of emitters and a plurality of detectors arranged with respect to the panel, the plurality of detectors configured to receive light from the plurality of emitters thereby defining detection samples of light transmitted between pairs of emitters and detectors. The optical touch apparatus being further configured to operate in an ambient light evaluation mode comprising the steps of: generating a first set of samples over a first integration time and a second set of samples over a second integration time using at least one detector, and applying a filter to at least the first and second set of samples to generate a residual ambient light value indicative of ambient light noise, wherein the touch apparatus is configured to perform the following steps: operating according to the ambient light evaluation mode for a plurality of repetitions.

1 .- 23 . (canceled) 
     
     
         24 . A method of operating an optical touch apparatus, the optical touch apparatus comprising:
 a panel,   a plurality of emitters and a plurality of detectors arranged with respect to the panel, the plurality of detectors configured to receive light from the plurality of emitters,   a controller coupled to the plurality of emitters to generate the signals and wherein each detector is configured to generate an output signal,   the optical touch apparatus being configured to operate in a sequence of repetitions, each repetition comprising the steps of:   turning the emitters ON and OFF according to a timing configuration during each repetition such that the output signal for each detector is generated to comprise ON energy values and at least one OFF energy value,   processing the output signals to generate a set of data samples,   processing the set of data samples to detect an interaction with the panel,   generating a residual ambient light value, indicative of ambient light noise, from at least one of the data samples, and   modifying the timing configuration to optimise the residual ambient light value.   
     
     
         25 . The method of  claim 24 , wherein the data samples comprises ON values and OFF values corresponding to the ON energy values and OFF energy value of the output signal. 
     
     
         26 . The method of  claim 24 , wherein the residual ambient light value is generated in dependence on the OFF values of the data samples. 
     
     
         27 . The method of  claim 24 , wherein the timing configuration specifies a length of time an emitter is ON for each repetition. 
     
     
         28 . The method of  claim 24 , wherein the timing configuration specifies a length of time no emitter is ON for each repetition. 
     
     
         29 . The method of  claim 24 , wherein the timing configuration specifies a length of time for each repetition of the sequence of repetitions. 
     
     
         30 . The method of  claim 24 , wherein the residual ambient light value is generated in dependence on a difference between signals sampled when no emitter is ON. 
     
     
         31 . The method of  claim 24 , wherein a residual ambient light value is determined for each of a plurality of the detectors of the touch apparatus and wherein the optimal residual ambient light value is determined as a function of the plurality of residual ambient light values. 
     
     
         32 . The method of  claim 30  wherein the function is an average or maximum of the residual ambient light values. 
     
     
         33 . The method of  claim 24 , wherein the apparatus being configured to modify timing configurations in subsequent repetitions. 
     
     
         34 . The method of  claim 24 , wherein the length of time an emitter is ON is between 3 μs to 30 μs. 
     
     
         35 . The method of  claim 24 , wherein modifying timing configurations comprises modifying the length of time an emitter is ON in steps of between 0.1 μs and 20 μs each repetition. 
     
     
         36 . The method of  claim 33  wherein a residual ambient light value being below a threshold value and having the shortest length of time an emitter is ON is selected as the optimal residual ambient light value. 
     
     
         37 . An optical touch apparatus comprising:
 a panel,   a plurality of emitters and a plurality of detectors arranged with respect to the panel, the plurality of detectors configured to receive light from the plurality of emitters,   a controller coupled to the plurality of emitters to generate the signals and wherein each detector is configured to generate an output signal,   the optical touch apparatus being configured to operate in a sequence of repetitions, each repetition comprising the steps of:
 turning the emitters ON and OFF according to a timing configuration during each repetition such that the output signal for each detector is generated to comprise ON energy values and at least one OFF energy value, 
 processing the output signals to generate a set of data samples, 
 processing the set of data samples to detect an interaction with the panel, 
 generating a residual ambient light value, indicative of ambient light noise, from at least one of the data samples, and 
 modifying the timing configuration to optimise the residual ambient light value.