Color electrographic recording apparatus

In a color electrographic recording apparatus for producing on a recording medium a composite color image comprising a plurality of superimposed component images of different colors and comprising

• means for transporting said recording medium along a predetermined path through said apparatus,
• a recording station in said path and having a recording head with electrode means for forming a latent image on said recording medium,
• control means operative to energize said electrode means to create said latent image,
• a plurality of developing means adjacent at least one side of said recording station, each of said developing means for developing a latent image produced on said recording medium at said recording station into a corresponding visible component image of a respective color,
• said transport means operative to pass a section of said recording medium through said recording station to form a component latent image followed by its respective color development and reverse the direction of medium transport to permit formation of the next component latent image followed bt its respective color development and repeating this process until all component latent images and their respective color development have been completed to form said composite color image,
• registration means associated with the transport of said recording medium and said control means to form each component latent image so that said component color images will be superimposed on one another,
• said registration means includes recording means at said recording station to form latent tracking indicia on said recording medium outside the field of said composite color image followed by its visible development during the first pass of said recording medium section through said recording station and
• means associated with the transport of said recording medium to sense said tracking indicia and produce information on-the-fly indicative of positional locations both longitudinally and laterally along said recording medium section to permit longitudinal and lateral registration of said component latent images.

In a color electrographic recording apparatus for producing a composite color image comprising a plurality of superimposed component images of different colors on a recording medium and including registration means associated with the transport of said recording medium through said apparatus for determining any shrinkage or expansion of said medium during said transport and creation of said composite color image and comprising

• a series of aligned tracking indicia on said medium,
• said tracking indicia having a known spacing relationship and representative of a known value,
• initializing indicia preceding said tracking indicia and having an optically recognizible distinctive feature relative to said tracking indicia,
• electro-optic sensor means positioned to observe said indicia as said recording medium is transported through said apparatus,
• circuit means coupled to said electro-optic sensor means to produce a signal representative of the spacing relationship of said indicia,
• circuit means responsive to said signal indicative of recognition of said initializing indicia and determinative of the point of transition from the last of said initializing indicia to the first of said tracking indicia indicative of the starting point for each of said component color images.

In a color electrographic recording apparatus for producing a composite color image comprising a plurality of superimposed component images of different colors on a recording medium and including registration means associated with the transport of said recording medium through said apparatus for determining any shrinkage or expansion of said medium during said transport and creation of said composite color image and comprising

• a series of tracking indicia on said medium adjacent both edges thereof,
• said tracking indicia having a known spacing relationship between the series of said indicia along said medium edges as well as along each of said medium edges, said spacing relationships representative of known values,
• electro-optic sensor means positioned to observe said indicia as said recording medium is transported through said apparatus,
• said circuit means coupled to said electro-optic sensor means productive of signals representative of the spacing relationship of said indicia both laterally and longitudinally of said medium,
• means to compare said signals with said known values and produce error signals representative of any difference due to said comparisons, said error signals respectively representative of shrinkage or expansion of said medium occurring both laterally and longitudinally during said medium transport, and
• means responsive to said error signals to correct for misalignment imposed upon the formation of said component color images due to medium shrinkage or expansion both laterally and longitudinally of said medium thereby maintaining on-the-fly image superimposition.

The method of ensuring superimposed color component images on a section of recording medium in the production of individual color component images to form a multicolor composite image by a color electrographic recording apparatus comprising the steps of

• forming a series of tracking indicia on the medium adjacent at least one edge thereof, the indicia having a known spacing relationship and representative of a given value,
• providing some of the initial of said tracking indicia with a differently observable characteristic,
• observing the indicia as the medium is moved through the apparatus,
• determining the transition point from said initial tracking indicia to the remaining tracking indicia based upon said characteristic,
• counting said remaining tracking indicia from said transition point to a predetermined point wherein the production of each of said color component images is to be initiated,
• determining whether the value obtained from the observed spacing of said indicia is the same or different from said given value,
• processing any differences in the values to form a correction signal representative of either a shrinkage or expansion of the medium section, and
• applying the correction signal in the production of the color component images to prevent image misalignment due to medium shrinkage or expansion occurring during the production process.

In a color electrographic recording apparatus having a multistylus recording head for sequentially creating successive latent electrographic lines on a moving recording medium together representing a composite image and wherein multiple passes of the same region of said recording medium relative to said recording head creative of a composite color image comprising a plurality of superimposed component images of different colors, registration means associated with the transport of said recording medium through said apparatus for determining any shrinkage or expansion of said medium during medium transport and the creation of said composite color image and further comprising

• a series of tracking indicia on said medium adjacent at least one edge of thereof,
• said tracking indicia having a known spacing relationship and representative of a known value,
• initializing indicia preceding said tracking indicia and having an optically recognizable distinctive feature relative to said tracking indicia,
• electro-optic sensor means positioned to observe said indicia as said recording medium is transported through said apparatus,
• circuit means coupled to said electro-optic sensor means to produce a signal representative of the spacing relationship of said indicia,
• electrographic circuit means responsive to said signal indicative of recognition of said initializing indicia and determinative of the point of transition from the last of said initializing indicia to the first of said tracking indicia,
• said electrographic circuit means further including means to compare said signal with said known value and produce an error signal representative of any difference due to said comparison, said error signal representative of shrinkage or expansion of said medium during medium transport, and
• means responsive to said error signal to accordingly either delay or advance the placement of said successive latent electrographic lines in the formation of said component color images due respectively to either medium shrinkage or medium expansion thereby maintaining on-the-fly image superimposition.

In a color electrographic recording apparatus having a multistylus recording head for sequentially creating successive latent electrographic lines on a moving recording medium together representing a composite image and wherein multiple passes of the same region of said recording medium relative to said recording head creative of a composite color image comprising a plurality of superimposed component images of different colors, registration means associated with the transport of said recording medium through said apparatus for determining any shrinkage or expansion of said medium during medium transport and the creation of said composite color image and further comprising

• a series of aligned tracking indicia on said medium,
• said tracking indicia having a known spacing relationship and representative of a known value,
• electro-optic sensor means positioned to observe said indicia as said recording medium is transported through said apparatus,
• circuit means coupled to said electro-optic sensor means to produce a signal representative of the spacing relationship between each of said observed indicia,
• said electrographic circuit means further including means to compare said signal with said known value and produce an error sample representative of any difference due to said comparison,
• means to average a plurality of said error samples together and produce an error signal representative of a running average in the shrinkage or expansion of said medium during medium transport and employed to either delay or advance the placement of said successive latent electrographic lines in the formation of said component color images due respectively to either medium shrinkage or medium expansion thereby maintaining on-the-fly component image superimposition.