| 摘要 |
在矩阵影像感测器中，读取行的像素之方法允许行提供的电压位准之类比-数位转换的二模式：第一模式，在具有额定持续时间dn的额定转换时间窗FCONV中执行单一类比-数位转换，以及，计数随着具有额定持续时间dn的斜坡而启始以及在比较器的输出SCMP触发时停止；以及，第二模式，在相同的额定转换时间窗中，藉由与具有缩减的持续时间dr之斜坡相比较而提供多次转换。在斜坡启始的瞬间ti后预定持续时间之后，根据侦测比较器的输出SCMP的状态之观测，选取要施加的转换模式：假使该输出触发时，则要转换的有用等级代表低亮度级，对有用等级施加具有多次转换的第二模式；假使输出未触发时，则要转换的有用等级代表高亮度级，对有用等级施加具有单一转换之第一、传统的模式。本发明藉由降低导因于转换链的电路之高斯杂讯量，而能够对低亮度级改良感测器输出的讯号对杂讯比。; and a second mode which provides for multiple conversions by comparison with a ramp of reduced duration dr, in the same nominal conversion time window. The selection of the mode of conversion to be applied is based on the observation of the state of the output SCMPof the comparator after a predetermined duration after the instant tiof ramp start: if the output has toggled, the useful level to be converted represents a low light level to which the second mode with multiple conversions will be applied; if the output has not toggled, the useful level to be converted represents a high light level and the first, conventional, mode with single conversion will be applied. The invention makes it possible to improve the signal-to-noise ratio at the output of the sensor, for low light levels, by decreasing the amount of the Gaussian noise due to the circuits of the conversion chain. |
