Abstract: A sheet feeder may include a feed roller for compelling a sheet from a stack of sheets into a sheet path and a pair of separation rollers rotating in the same direction for urging sheets along the sheet path. The separation rollers may be selectively and separately disengaged from their motive source in coordination with operation of a motor for the feed roller to provide multiple checks for sheet multifeeds. At each check, extra sheets are returned to the stack of sheets. The separation rollers may each include plural annular spaced-apart sheet contact surfaces that are interleaved with the contact surfaces of the other roller.

Abstract: A sheet feeder may include a feed roller for compelling a sheet from a stack of sheets into a sheet path and a pair of separation rollers rotating in the same direction for urging sheets along the sheet path. The separation rollers may be selectively and separately disengaged from their motive source in coordination with operation of a motor for the feed roller to provide multiple checks for sheet multifeeds. At each check, extra sheets are returned to the stack of sheets.

Abstract: A laser driver mechanism for image reproduction maintains linear operation over a wide frequency an dynamic range of amplitude-modulated input signals by means of a first feedback loop and a second feedback loop. The second feedback loop contains a first amplifier coupled to receive the input signals and an output coupled to a second amplifier that drives an injection laser diode. A photodetector is coupled downstream of and external to a sealed unit in which the injection laser diode emitter, an associated photodetector of the first feedback loop and beam extraction optics are housed. The photodetector of the second loop has an output coupled to the second amplifier, so that the second feedback loop serves to compensate for non-linearities in the laser driver including those of the first feedback loop.

Abstract: A laser driver mechanism for image reproduction maintains linear operation over a wide frequency an dynamic range of amplitude-modulated input signals by means of a first feedback loop and a second feedback loop. The second feedback loop contains a first amplifier coupled to receive the input signals and an output coupled to a second amplifier that drives an injection laser diode. A photodetector is coupled downstream of and external to a sealed unit in which the injection laser diode emitter, an associated photodetector of the first feedback loop and beam extraction optics are housed. The photodetector of the second loop has an output coupled to the second amplifier, so that the second feedback loop serves to compensate for non-linearities in the laser driver including those of the first feedback loop.

Abstract: Problems of wear and bounce created by imperfections in the surface of a magnetic recording medium, such as a chromium dioxide-coated drum, are circumvented by a hydrodynamic magnetographic imaging technique that provides the intended effective intimate contact between the recording head the magnetographic recording surface. A readily evaporatable liquid (e.g. water, alcohol, acetone) is applied to the surface of the drum slightly upstream of the location of the recording head, so as to create a liquid bearing against which the recording head is urged, and thereby intimately magnetically coupled with the surface of the drum, except for an extremely thin liquid film between the head and drum surface. As a result of this extremely thin liquid bearing, continuous pressure can be applied to the head to maintain the head in effective intimate contact with the surface of the recording medium without the fear of scratching the medium or causing wear on the head.

Abstract: Apparatus for analyzing an image member such as a photographic film bearing an image to be printed and providing information as to the image area. The information may be utilized in determining initial ink key settings for a printing cylinder on which the image is to be printed. The image member is positioned on a support surface and a scanner assembly including a light source and light sensors scans the surface. Light transmission readings are taken from calibration film strips on the support surface and at positions on the support surface corresponding to the locations of the ink key columns of the printing cylinder. The data are calibrated and normalized using the calibration readings. The data are also corrected for the number of layers in the image member. Data from ink key columns which will not be utilized in printing the image analyzed are discarded. A procedure is provided for removing the effect on the data of any non-image material on the image member.