In SAR ADCs or Pipeline ADCs, which are widely used in image sensors, the conversion processing time increases proportionally to the number of output digital bits corresponding to the output resolution. Both SAR ADCs and Pipeline ADCs in principle discriminate digital codes corresponding to the main components of the input analog signal and coarse them and fine-tune the remaining components to higher resolution digital codes. The conversion time proportional to the output bit is required. The ADC used in the image sensor is usually 8 to 12 bits, and divides the signal of light incident on each pixel of the image sensor into 256 stages to 4096 levels. On the other hand, the confocal three-dimensional measurement is a method in which only the relative light intensity values at the respective measurement positions are compared with each other to find the point having the highest light intensity and the three-dimensional height value is converted, Level resolution. Even if the light intensity is extremely 1 bit, if the value is 1 at the focal point in the confocal method and the measured value of the light is 0 at the remaining point, by finding the point where the light intensity is 1, which is the maximum value, The value is known. As described above, in the confocal 3D measurement method, a 2D image sensor having a high output bit resolution is not needed because only the relative light intensity value difference can be distinguished in each pixel rather than the image quality itself. The output bit resolution of the 2D image sensor may not lead to the 3D measurement resolution, but rather causes the measurement speed to be deteriorated, thereby causing difficulty in increasing the 3D measurement resolution. Therefore, by using the image sensor using an ADC that can adjust the output bits of the SAR ADC or Pipeline ADC and speed up the frame processing by reducing the conversion time instead, it can be used for confocal 3D scanning, Dimensional mouth scanner can be i
