Abstract: Digital character signals are split into at least two bit groups of different binary significance. The first and most significant of the bit groups is registered and periodically sampled for conversion in a resistor network to an analog format. The bits of the second, or least significant, bit group are utilized to produce a signal train including in a character time a number of pulses determined by the value of the second bit group and which pulses are approximately evenly located in the interval of the character. Each pulse of the train, as it occurs, momentarily augments the most significant bit group.One embodiment is shown in which the signal train produced is successive overflow carries from a high speed accumulation operation initially utilizing the least significant bit group and a starting character and thereafter using the least significant bit group and the immediately preceding accumulation sum.

Abstract: In each character time of a pulse code modulation signal stream, the most significant bit group of the PCM character is reversibly incremented and decremented a plurality of times. The incrementing and decrementing is carried out in a selectable sequence for each discrete pair of subintervals in the character time. The selectable sequences are determined by the value of the least significant bit group of the character whereby the average value, over the character time of an analog signal derived from the changing most significant bit group information in each subinterval, is equal to the value represented by the character.

Abstract: A two-dimensional planar display device includes a plurality of plasma discharge shift registers positioned along rows of a display matrix. Each resolution element along a row includes two stable discharge locations, a first of which is optically masked. Modulating the duration of propagation signals associated with the second discharge location, the duration for propagation signals for the entire resolution element being constant, permits the generation of continuously variable brightness levels. In a preferred embodiment, glow discharges propagating down an additional one or more column shift registers are sequentially coupled to row shift registers to permit rapid scanning over the entire two-dimensional array.

Abstract: A light pen tracking system and method particularly adapted for use with a plasma panel in which a first plurality of display sites on a display device are sequentially excited in such manner as to generate a signal which may be detected by a light pen. Upon detection of a first light signal, a second set of display sites centered at a location identified by the first signal and having smaller area than the first scanned area is then scanned. Because a relatively small area is scanned in the second scanning mode, and because the center of this smaller area has been localized by the previous signal detection, it is possible to more closely track rapid movements of a light pen on a display surface.