Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
This article describes the concept of compensating the unflatness of an image output signal of an image sensor. A portion of an input signal to a digital-to-analog converter, to which the image output signal is applied, is blended to its output signal, or a current is fed back to the input of the digital-to-analog converter from its output to realize the optimized compensation. An image sensor 1 in a document-reading apparatus has plural sensor elements arranged in a line along the width of a document 2. A light from a fluorescent lamp 3 is reflected from the document 2. The reflected light through a lens 4 is sensed by the sensor elements to produce image signals, which are serially supplied to a sample and hold circuit 5 and a black level clamp circuit 6.