FIELD: information technologies.
SUBSTANCE: document reading device includes a setting plate of a document, arranged with the possibility to locate the document for the purpose of reading on the plate; a source of light, configuration of which provides for radiation of light at the area, where the document is located, on the setting plate of the document; an image sensor, configuration of which provides for a photoelectric conversion of a reflected light from the light radiated by a source of light to display colour signals; and a unit to detect a size of the document, configuration of which provides selection of a colour signal, used to determine the document size from a number of output colour signals from the image sensor, being based on the output colour signals from the image sensor with the light source being disconnected; and also provides determination of the size of the document arranged on the setting plate of the document, being based on the selected output colour signals from the image sensor with the connected source of light.
EFFECT: detection of a document size without regard to the effect of the surrounding light.
10 cl, 17 dwg
