Image reader for X-ray film or the like having a detection system with an expanded dynamic range
 An image reader having a high sensitive detection system for detecting a variation in a first light quantity to generate a first output, a low sensitive detection system for detecting a variation in a second light quantity to generate a second output where the second light quantity is greater than the said first light quantity, and a signal composing circuit for receiving the outputs of the high and low sensitive detection systems, each of the detection systems being so disposed as to detect simultaneously or substantially simultaneously a ray bundle from a picture element of a picture, and the output of the signal composing circuit being (a) the output of the high sensitive detection system when the received light quantity is smaller than a threshold light quantity which can be detected with substantially the same degree of accuracy by both the detection systems or (b) the sum of (i) the output of the low sensitive detection system and (ii) the difference between the outputs of the detection systems at the threshold light quantity whereby a time-serial output of wide dynamic range is obtained. 
Hitachi Medical Corporation
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inventional inventional additional inventional inventional inventional inventional
Shigeru Ken Mitsuru
Watanabe Ishikawa Ikeda