Abstract: The object of the invention is to provide a means of circulating inked ribbon into and out of a cartridge where it has been stored as a compact mass of ribbon folds. Means must be provided to prevent this mass of ribbon from jamming the exit port and forming clumps which result in excessive ribbon tension at the exit.This has been accomplished by introducing a plurality of restrictors in the cartridge ahead of the exit port. In one embodiment, the first of these restrictors consists of a single dam positioned such that the mass of folded, compressed ribbon is restrained by this dam. Tension of withdrawal causes a small quantity of ribbon length to separate from the ribbon mass and cross the restrictor in small clumps or folds. The second restrictor which in one embodiment consists of two aligned dams, one above and one below, causes the ribbon to be restrained to the degree that it exits after passage as a single, unfolded ribbon under slight tension.

Abstract: A settable margin control switch is actuated when a movable carriage printer approaches the right hand margin. In the keyboard operating mode, an audible alarm is sounded and a predetermined number of character positions later, the printing of keyboard originated data is blocked. In the automatic printing mode, no alarm is sounded, however, printing is terminated and a special character is printed beyond the right hand margin to indicate that the input data has overflowed the printed record.

Abstract: A waveguide opening for moving paper in and/or out of a data printer employing wave attenuators and reflectors to suppress electromagnetic wave radiation generated within said printer from escaping through the paper opening.

Abstract: A mechanism to limit the starting and stopping movement of a print head in a printing operation comprising moving a plurality of character representing signals in memory from a source to the printing operation at a rate in excess of the rate at which characters are normally available from the source such that a substantial number of characters are printed along a line on a record medium before the memory storing the character signals is empty of the initially stored character signals and the additional character signals received during the printing operation. Overrides are provided depending on the frequency of data received from the source and the appearance of a control code in memory.

Abstract: A photoelectric detection system for a printer that is particularly useful for accurately detecting the position of type bearing or printing elements of known width and spacing as they pass a predetermined location. An output signal is generated that substantially corresponds to the light and dark periods created as the elements pass between a light source and detector. This output signal is integrated and compared with a reference signal that represents the ratio of the width of the elements to the spacing therebetween and the error is used to modify the light source and thereby adjust the output signal to accurately correspond with the dimensional criteria of the elements.

Abstract: A data interface between a plurality of data sources and a printer wherein the interface can accept data from such sources on a pre-established priority basis. The priority of any source is determined by the time relationship of its bid strobe signal to a synchronizing signal. The bid strobe signals are timed to occur at different time intervals in accordance with the pre-established priority basis.

Abstract: Maximizing the printing rate of an electronic printer by causing it to print data characters at a relatively constant rate despite variations in the pattern of the incoming data. The number of characters in an incoming data pattern to be printed substantially simultaneously is monitored and the printing rate controlled within certain limits to provide a maximum printing rate consistent with the power and mechanical limits of the printer design.

Abstract: A printer arrangement of the type which prints data serially along a line on a record medium by relative impact of type characters and record medium through a ribbon. Printing is a mixture of stop and go printing, essentially a character at a time, and continuous printing of a plurality of characters. Driving power for the ribbon is derived from carriage movement on which the print head is mounted through controllable clutch and toggle switch action. The toggle switch action reverses ribbon drive direction in response to a depletion of ribbon signal.