| 摘要 |
Each pixel detector of an array comprises: a photosensor 2 providing a signal representing a time integral of detected light intensity; a reference signal generator 4, the signal varying according to a predetermined function, which is preferably non-linear, the rate of change decreasing; a comparator 6 generating a capture signal from the photosensor 2 signal and the reference generator 4 signal, preferably when the signals are equal, and; a read out device 10 capturing a read out signal upon receiving the capture signal, preferably being disconnected from the photosensor 2 via a switch 8 at this time. The read out signal represents a logarithm of detected light intensity. Preferably the photosensor 2 signal is a voltage across a capacitance 16 that is charged and discharged by current dependent on light intensity conducted by the photosensor 2. A reset device 12 preferably initiates discharge of the capacitance by the photosenor 2 current. An index signal (123, fig. 8) may be provided, the read out signal being related to it. A method is also independently claimed. |
