Automatic optimisation of touch signal

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 thereby defining detection samples of light transmitted between pairs of emitters and detectors,
• 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 data sampling mode operating 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 for the detection samples and at least one OFF energy value,
• processing the output signals to generate a set of data samples, each data sample being generated to represent detected energy for one of the detection samples, and
• processing the set of data samples to detect an interaction with the panel,
• 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 method comprises the steps of:
• operating the optical touch apparatus according to the ambient light evaluation mode for a plurality of repetitions, wherein the length of at least one of the first integration time and second integration time vary between repetitions,
• selecting the first integration time and/or second integration time that generated an optimal residual ambient light value, and
• operating the optical touch apparatus in the data sampling mode with a timing configuration corresponding to the selected first integration time and/or second integration time.