| 摘要 |
In photoelectric apparatus such as a pulse oximeter for monitoring a parameter of the blood in a living organism, a dark current correction signal is applied to the input at the preamplifier. The correction signal is substantially equal in magnitude but opposite in sense to the photodetector output during dark intervals when the illumination means of the apparatus is disabled. Because dark current correction is accomplished at the input of the preamplifier, the preamplifier has substantially increased resistance to overloading caused by ambient light and hence may have higher gain. |
