| 摘要 |
<p>An optical sensing array (52) is adapted to filter incident light so as to generate two output electrical signals from two different portions of the array. The sensing array, which can be a linear CCD array, is assembled with a glass filter (53) overlying the array, the filter being coated with a material (54) which transmits light over a selected wavelength range. One portion of the glass filter is uncoated (55). Thus a light source incident on the array will activate two separate parts of the array; one underlying the uncoated part and the other underlying the coated portion. This results in two different responses over different portions of the spectrum and results in generation of two electrical signals of different levels, representing different detected wavelengths of light. These electrical signals are useful to represent different functions; for example, various characteristics such as the background density and size of a document being copied on a xerographic copier.</p> |
