Exposure mechanism of optical touch system and optical touch system using the same

An optical touch system, comprising:

• a touch surface;
• a plurality of irradiation light bars disposed at edges of the touch surface, respectively;
• a first image sensor configured to capture image frames looking across the touch surface in a first sampling interval and a denoising sampling interval to respectively obtain a first bright image and a first dark image, wherein the irradiation light bars within a field of view of the first image sensor irradiate corresponding to the first sampling interval;
• a second image sensor configured to capture image frames looking across the touch surface in a second sampling interval and the denoising sampling interval to respectively obtain a second bright image and a second dark image, wherein the irradiation light bars within a field of view of the second image sensor irradiate corresponding to the second sampling interval;
• and
• a processing unit configured to calculate a first differential image between the first bright image and the first dark image and calculate a second differential image between the second bright image and the second dark image,
• wherein the first sampling interval is longer than the second sampling interval, and the denoising sampling interval is equal to the second sampling interval.

An exposure mechanism of an optical touch system, the optical touch system comprising a plurality of image sensors and a plurality of active light sources, each of the active light sources irradiating corresponding to the associated image sensor, the exposure mechanism comprising:

• capturing image frames using the image sensors with a first sampling cycle to allow each of the image sensors to capture a first bright image, wherein the first sampling cycle comprises a plurality of working modes and in each of the working modes at least one of the image sensors captures the first bright image in a sampling interval;
• simultaneously capturing a dark image using all the image sensors in a denoising sampling interval, which is subsequent to the first sampling cycle;
• capturing image frames using the image sensors with a second sampling cycle, which is subsequent to the denoising sampling interval, to allow each of the image sensors to capture a second bright image, wherein the second sampling cycle comprises a plurality of working modes and in each of the working modes at least one of the image sensors captures the second bright image in the sampling interval;
• and
• calculating, using a processing unit,
• a first differential image between the first bright image and the dark image captured by each of the image sensors, and
• a second differential image between the second bright image and the dark image captured by each of the image sensors.

An optical touch system, comprising:

• a touch surface;
• a plurality of irradiation light bars disposed at edges of the touch surface, respectively;
• a first image sensor configured to capture image frames looking across the touch surface in a first sampling interval and a denoising sampling interval to respectively obtain a first bright image and a first dark image, wherein the irradiation light bars within a field of view of the first image sensor irradiate corresponding to the first sampling interval;
• a second image sensor configured to capture image frames looking across the touch surface in a second sampling interval and the denoising sampling interval to respectively obtain a second bright image and a second dark image, wherein the irradiation light bars within a field of view of the second image sensor irradiate corresponding to the second sampling interval, wherein the first sampling interval and the second sampling interval form a first sampling cycle, and the denoising sampling interval is subsequent to the first sampling cycle;
• the first image sensor is further configured to capture a bright image in a first sampling interval of a second sampling cycle subsequent to the denoising sampling interval, and the irradiation light bars within the field of view of the first image sensor irradiate corresponding to the first sampling interval of the second sampling cycle;
• the second image sensor is further configured to capture a bright image in a second sampling interval of the second sampling cycle subsequent to the denoising sampling interval, and the irradiation light bars within the field of view of the second image sensor irradiate corresponding to the second sampling interval of the second sampling cycle;
• and
• a processing unit configured to calculate
• a first differential image between the first bright image and the first dark image,
• a second differential image between the second bright image and the second dark image,
• a differential image between the bright image of the first sampling interval of the second sampling cycle and the first dark image, and
• a differential image between the bright image of the second sampling interval of the second sampling cycle and the second dark image.