Optical scanner having a variable resolution

Abstract

An optical scanner having a variable resolution wherein an optical detecting unit controlled by a pixel clock signal generates a discrete signal representing pixels scanned in a region. An analog-to-digital converter converts the signal to a digital signal with a preselected resolution controlled by a sample clock generator. The sample clock generator receives the pixel clock signal, and through a counter and a store, operates an addressed, binary data word which is sent to a register. The register is coupled to a further periodic clock generator that controls reading from the register and provides a clock signal with pulses when the bits of the data word assume a first binary state, and no pulses when the bits assume a second binary state. The clock signal is passed to the analog-to-digital converter as a sample clock signal.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe invention generally concerns optical scanning systems, including systems having a high resolving power for scanning documents and the like to generate digital, binary data which represent the scanned information. The scanned information can then be stored electronically for later computer processing. There is a great need for a facility for the scanning of documents, drawings and similar materials, thereby saving storage space and facilitating corrections of drawings, etc.2. Background of the InventionSince scanning systems of this type are designed to scan very broad documents, the optical system in front of the actual scanning unit or the CCD camera will be utilized to the utmost. Thus, use is made of very expensive lens beams which are either mounted mechanically very stably or are stitched together, as shown in U.S. Pat. No. 5,117,295. The optical system is arranged stationarily in front of the CCD cameras, and the scanning...

AI Technical Summary

Benefits of technology

is therefore to provide an optical scanning syste

Problems solved by technology

Thus, use is made of very expensive lens beams which are either mounted mechanically very stably or are stitched together, as shown in U.S. Pat. No. 5,117,295.

According to the method disclosed in these documents it is not possible to select an arbitrary position of these estimated grey level values, because of the limitations imposed by the algorithms on which the method is based.

Thus, it is not possible to choose an arbitrary resolution of the written data, which is generally desirable in many cases.

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