Abstract: A printer of the daisywheel type in which the existence of a carriage control signal and a printwheel control signal operate inhibiting apparatus for a control signal otherwise gated to a paper feed operator.

Abstract: A printwheel for an impact printer is disclosed. The printwheel has a central hub in which are located several index holes. The printwheel is also provided with multiple sets of character of symbol type fonts, each set having an index hole associated therewith and each index hole being located in the same relative position with respect to its associated set.

Abstract: A digital servo system adapted for use in a dual mode coarse-fine servo system to control a movable member from a starting position to an at rest destination position. The digital servo generates a pulse train in response to varying space phase cyclic analog position signal A from an encoder coupled to the movable member. Each cycle of an analog position signal represents a small incremental amount of movement by the movable member. The pulse train provides a change in its state in time with the varying position signals. In the preferred embodiment, eight changes occur per cycle. The pulse train is integrated to provide a velocity signal which is compared with a command velocity signal.

Abstract: An impact printer, for example, of the daisy wheel type with plotting capability is provided by utilizing a cartridge which instead of an inked ribbon has a marking pen mounted through the cross-section of the cartridge and is selectively engageable against the paper by the use of the existing ribbon lift mechanism.

Abstract: A dual mode servo-system providing improved motion characteristics and improved noise immunity. A relatively movable member is driven by control signals derived from actual velocity feedback signals during coarse mode operation. At the beginning of fine mode operation the actual velocity signal is sampled and used to generate a synthetic velocity signal used to control motion of the member during final deceleration, along with an actual position feedback signal, the synthetic velocity signal having a decreasing magnitude tailored to a particular application. At a predetermined maximum time period, after detent of the member, a time out circuit re-inserts the actual velocity feedback signal.Control signals for the driven member are also derived from the actual motor current by integrating the motor current, the integrated current signals being used to control motion of the member during coarse mode operation only.

Abstract: A daisy wheel printer which accommodates different print wheel fonts has switchable ROMs each containing print position and instruction information for each character on an associated print wheel. The possible number of printing positions is substantially double the number of characters carried on a print wheel.

Abstract: An impact printer of the daisywheel type mechanically links together two daisywheel printer carriages so that the total number of different characters that can be printed is doubled. Suitable coordination logic provides for operation in a first concurrent (or parallel) mode where the user's software looks ahead to provide for continuous printing along a single line. The other mode of operation is sequential where the twin print heads are substantially transparent to the user's system and thus the appropriate print head automatically positions itself to a printing position.

Abstract: A low cost cartridge for supplying inked ribbon to the printing station of an associated printing device. The cartridge includes an internal tensioning mechanism for maintaining the length of inked ribbon positioned in the printing station at a constant tension independently of the quantity of ribbon remaining on the supply reel in the cartridge. The tensioning mechanism includes an elastic endless belt disposed in a closed path about a plurality of freely rotatable rollers, the path having an interference region in which portions of the belt are engaged by a portion of the outer layer of supply reel mounted ribbon and are deflected thereby to produce a drag force on the supply reel which varies with the pulling force required to withdraw ribbon from the supply reel.

Abstract: The print wheel and carriage position control signal generators each employ an LED light source for illuminating light sensitive detectors associated with the timing track of an encoder disc rotatably mounted on the print wheel or carriage motor shaft. The detectors are arranged to generate a pair of signal trains having a constant phase displacement in response to rotation of the associated disc. These signal trains are shaped and processed to provide position reference signals used to control an associated position counter unit and an electronic servo control system for driving the associated motor, the servo control system having both a position and a rate mode of operation. A separate light sensor is arranged to be constantly illuminated by the LED source to provide intensity monitoring signals which are compared with a reference voltage in a feedback circuit so that any variation in the light intensity is automatically corrected.

Abstract: An endless ribbon cartridge for supplying ribbon to an external printing station with relatively uniform tension and including an anti-fouling mechanism to prevent snarling of the ribbon as it re-enters the cartridge. The cartridge comprises a two-piece housing having a cover and a main body portion with separate exit and entrance slots and interior boundary walls partially defining a ribbon chamber having entrance and exit portions. An endless ribbon is partially received within the chamber in random folds, the remainder of the ribbon traversing a looped path from the chamber exit portion through the housing exit slot and the housing entrance slot to the chamber entrance portion. A capstan and pinch roller assembly is provided adjacent the entrance slot to translate the ribbon along the looped path.

Abstract: An improved pin feed platen providing a positive pulling force on a print medium in a forward and reverse direction at the forward and reverse exit locations of a platen work station and affording easy initial loading of the medium to be transported.A platen pin feed assembly includes housing means mounted for rotation with a platen and having a plurality of radially extending feed pin bores distributed about the axis of rotation, a plurality of feed pins each radially translatably received in a different one of the feed pin bores and each having an inner end, a tapered outer end and a camming slot located therebetween, and a camming member non-rotationally mounted with respect to the housing means.

Abstract: Apparatus for driving a cartridge mounted rotatable ribbon capstan and take-up reel. A magnetic clutch assembly has a first gear driven by a motor for directly driving the capstan and a second gear magnetically driven by the first gear for driving the take-up reel through a gear train. The magnetic clutch assembly includes a magnetic drive ring secured to the first gear and having a plurality of inner peripheral teeth, a pair of annular magnetic members mechanically linked to the second gear, an annular magnet disposed between the magnetic members and a magnetic washer disposed below the lower magnetic member. The magnetic clutch assembly provides a yieldable driving force to the take-up reel which releases when the tension in the ribbon between the capstan and the take-up reel exceeds a predetermined threshold value. This threshold value may be adjusted by varying the dimension of the magnetic washer or the air gap between the drive ring and the annular magnetic members.