Abstract: A printer/plotter incorporates four individual microprocessor-based print stations, each for printing on a print media a separate color image for superimposition with one another, forming a final full-color image. The four print stations are located along a transport path for single-pass operation, and each print station includes a transport system that allows the media to traverse a print station with controlled forces exerted on the media by that station. The invention further includes a precise registration system wherein each print station monitors registration marks to detect variations of the media (i.e., stretching or shrinkage) during the printing process and to correct for such variations on obtaining accurate registration of the individual images for a full-color result.

Abstract: A method for determining the position of media in a system where images are applied to the media at subsequent stations includes the steps of placing on the media at a first position tracking information consisting of a pattern of electrostatic charge to provide information with regard to the alignment of the media at the first station, and at the second station detecting the pattern of electrostatic charge to determine the alignment of the media at the second station. Typically the media consists of electrostatic paper and the step of placing charge on the paper is achieved by positioning positively charged styli in close proximity to the surface of the paper.

Abstract: A color printer/plotter includes a frame having a paper inlet, a number of print stations, and a paper outlet. The paper is pulled past the print stations by a single driver at the paper outlet. Each print station includes a electrostatic charging head having a flat charging surface against which a first roller, typically having a foam outer surface, presses with the paper therebetween. Immediately downstream of the charging head a toner roller supplies toner to the paper, the toner adhering to the charged areas on the paper. A second pressure roller presses the paper against the toner roller. The second pressure roller is offset slightly upstream of the center of the toner roller to aid toner roller-paper contact. The sizing and positioning of the toner and second pressure rollers is such so as not to significantly deflect the paper from the substantially straight paper path between the paper inlet and paper outlet.

Abstract: An assembly for mounting a roll of paper or Mylar.RTM. film having a hollow core includes a radially expanding core insert at each end of the roll and a core insert support, mountable to a support structure, to support, position and apply a drag force to the paper roll. Each core insert has a radially expandable inner end which is expanded within the core to secure the insert in place. The outer end of the core insert extends beyond the edge of the paper roll. The core insert support includes a pair of arcuate contact surfaces and an adjustable spring biased brake shoe mounted to a frame. The brake shoe presses the outer end of the core insert against the contact surfaces to create a suitable drag on the paper roll. A flipper is pivotally mounted to the frame for movement between free movement and blocking positions to permit or prevent the core inserts from being removed from the core insert supports. Each flipper also axially biases the core insert towards the other flipper.

Abstract: A color image processing system is described which provides more realistic hard copy color images from composite video system input signals than previously available. The image processing system includes a synchronization separator 20 which operates to separate the synchronization pulses from the analog video information supplied to it. The analog video information is then converted to digital form by an analog-to-digital converter. The converter operates under control of a time base generator 100, including a programmable delay line 300, which receives synchronization pulses from the synchronization separator, and following a programmable time delay supplies a control pulse to the converter to cause it to sample the analog waveform and convert it to digital format. Once the signal is digitized, it is converted from an additive color system to a subtractive one end enhanced before being supplied to the color plotter 8.

Abstract: An image processing system includes a synchronization separator 20 which operates to separate the synchronization pulses from the analog video information supplied. The separator includes an amplifier with a pair of input terminals. The video is coupled to one of the input terminals and a feedback loop coupled between an output terminal and the other input terminal. In this manner the negative synchronization pulses may be amplified while the positive video signals are limited. The extracted sync signal is used to control an analog-to-digital converter 70. The analog video information is then converted to digital form by an analog-to-digital converter. The converter operates under control of a time base generator 100, including a programmable delay line 300, which receives synchronization pulses from the synchronization separator, and following a programmable time delay supplies a control pulse to the converter to cause it to sample the analog waveform and convert it to digital format.

Abstract: A color image processing system is described which provides more realistic hard copy color images from composite video system input signals than previously available. The analog video information is converted to digital form by an analog-to-digital converter. The converter operates under control of a time base generator (100). The time base generator (100) provides more accurate control over the converter than the system clock signal. The generator (100) receives pulses from the synchronization separator, and following a programmable time delay supplies a control pulse to the converter to cause it to sample the analog waveform and convert it to digital format. The generator (100) employs a delay line (300) to detect the fraction of a system clock period between the sync pulse and the next clock pulse. The specified number of clock pulses are allowed to elapse. Then the delay line (300) is used to provide the necessary further delay.

Abstract: An encoding disk including a multiplicity of linear gratings placed accurately on the disk to diffract a light beam to a fixed point in space accurately does so independently of the centering of the disk on its axis of rotation.

Abstract: An optical laser scanning system includes a hologram spinner disc (32) having diffraction grating facets (33) around its periphery. The spinner is susceptible to wobble and translational movement of the facets with respect to a plane perpendicular to the disc axis (35). Corrective means (37) in the form of a ray converging element (37) are provided to collect parallel diffracted rays from the facets in translated positions of wobble and converge such rays to a spacial spot scan (38) on an imaging surface (40). By orienting the spinner such that the diffracted light beam makes a 90.degree. angle with the incident light beam and then providing a parabolic cylinder to direct and focus the diffracted light beam on the imaging surface, the effects of both translational and angular wobble on the image formed are eliminated.

Abstract: A photoconductor material having high sensitivity to infrared light is provided therefore making it suitable for use in laser printers. The photoconductor of this invention has a dark decay of approximately 40 volts/second, thereby enhancing the use of this invention with infrared laser printers as compared to prior art infrared sensitive photoconductors. The photoconductor of this invention comprises cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium carbonate (CdCO.sub.3) and cadmium oxide (CdO) in a binder, and preferably also includes a small amount of copper dopant. The photoconductor of this invention is prepared by adding ammonia to a suspension of cadmium sulfide/cadmium carbonate in water and then adding hydrogen selenide to this suspended solution.

Abstract: A recording head for use in an electrostatic printer comprises four staggered rows of styli. Signals for driving each row of styli are transmitted through a buffer wherein the signals for the first row of styli are transmitted without delay to the styli, the signals for the second row of styli are transmitted with an appropriate delay of a first selected time, the signals for the third row of styli are transmitted with an appropriate delay of a second selected time and the signals for the fourth row of styli are transmitted with an appropriate delay of a third selected time. The delay means comprises a random access memory driven by address counters controlled by a control sequencer to function as a delay. The four staggered rows of styli are formed by a novel method wherein the styli in the second row are formed between the styli in the first row and the stylis in the third and fourth rows are formed by making use of the grooves formed between the styli in the first and second rows.

Abstract: A recording head for use in an electrostatic printer comprises four staggered rows of styli formed by a novel method wherein the styli in the second row are formed between the styli in the first row and the styli in the third and fourth rows are formed by making use of the grooves formed between the styli in the first and second rows. By forming the rows of styli on a cylindrical drum, two recording heads are obtained from each fabrication run wherein the recording head in one set of styli is the mirror image of the recording head in the other set of styli. Should an error occur in the manufacture of the styli by placing the third row of styli in the grooves where the fourth row of styli normally belongs, the resulting recording heads are identical to those obtained with the proper placement of the third and fourth rows with the exception that the position on the drum of each type of recording head is reversed.