Printing press and method

In a digital electrostatic printing press for printing a succession of images on print receiving material including

• supply means and delivery means supported in spaced relation and means for driving and guiding print receiving material therebetween along a predetermined processing path,
• a cylinder having a photosensitive surface and means supporting said cylinder along the processing path in a position to contact said material,
• means for rotating said cylinder such that said surface has a peripheral velocity and direction corresponding to movement of the material,
• charging means for creating a uniform electrostatic charge on said cylinder surface at a potential of at least 1000 Volts,
• exposure means extending transversely of said surface for directing a plurality of small parallel beams of radiant energy onto adjacent discrete areas of about 0.003 inch across said cylinder surface to cause selective dissipation of the charge on such discrete areas in the order of 100 to 300 Volts, thereby to form an electrostatic latent image as successive linear dot patterns transversely of said surface,
• said exposure means being located around said drum from said charging means such that the uniformly charged part of said surface is presented to said exposure means,
• developing means for applying a liquid developer to said cylinder surface to develop the electrostatic latent image, said developer including toner particles having a size in the range of i to 10 microns and a negative charge in the range of 60 to 75 picamhos/cm dispersed in a volatile carrier liquid,
• said developing means including a shoe member contoured to said surface of said cylinder and containing the liquid developer in contact with a predetermined area of said cylinder carrying the electrostatic latent image,
• said shoe member including development electrode means arranged for contact with developer in said shoe member,
• means for applying to said development electrode means a potential in the order of 200 to 600 Volts whereby the toner particles in the liquid developer are attracted to the image areas on said cylinder surface and repelled from the non-image areas of said cylinder surface,
• means guiding said print receiving material into contact with said cylinder surface at a region past said developing means in the direction of rotation of said cylinder,
• means for transferring the toner particles from the latent image onto the material, and
• means for fixing the toner particles to the print receiving material whereby the material can be printed with variable information and processed accordingly in a single press without need for printing makeready operations.

An electrostatic printing press for printing a succession of images on print receiving material, comprising

• supply means and delivery means supported in spaced relation and means for driving and guiding print receiving material therebetween along a predetermined path,
• a cylinder having a photosensitive surface and means supporting said cylinder along the path in a position to contact said material,
• means for rotating said cylinder such that said surface has a peripheral velocity and direction corresponding to movement of the material,
• charging means for creating a uniform electrostatic charge on said cylinder surface at a first high potential,
• exposure means extending transversely of said surface for directing radiant energy onto predetermined discrete non-image areas on said cylinder surface to cause selective dissipation of the charge on such discrete areas to a second low potential, thereby to form an electrostatic latent image on said surface,
• said exposure means being located around said drum from said charging means such that the uniformly charged part of said surface is presented to said exposure means,
• developing means for applying a liquid developer to said cylinder surface, said developer including toner particles having a negative charge and being dispersed in a volatile carrier liquid,
• said developing means including a shoe member contoured to said surface of said cylinder for containing the liquid developer in contact with a predetermined area of said cylinder carrying the electrostatic latent image,
• said shoe member including development electrode means arranged for contact with developer in said shoe member,
• means for applying to said development electrode means a third potential intermediate the first and second potentials whereby the toner particles in the liquid developer are attracted to the image areas on said cylinder surface and repelled from the non-image areas of said cylinder surface;
• the improvement comprising
• means for circulating the liquid developer through said shoe member to refresh developer depleted of toner particles and to flush concentration of toner particles away from said development electrode.

A web printing press for printing a succession of images on a web, comprising

• web supply means and delivery means supported in spaced relation and means for driving and guiding web material therebetween along a predetermined path,
• a cylinder having a photoreceptor surface and means supporting said cylinder along the processing path in a position to contact said web material,
• means for rotating said cylinder such that said surface has a peripheral velocity and direction corresponding to movement of the web material,
• charging means for creating a uniform electrostatic charge on said photoreceptor surface at a first high potential,
• exposure means extending transversely of said surface for directing discrete beams of radiant energy at a resolution in the order of at least 300 per inch selectively onto predetermined discrete non-image pixel areas on said surface to cause selective dissipation of the charge on such discrete areas to a second low potential, thereby to form an electrostatic latent image on said surface, said exposure means being located around said drum from said charging means so a uniformly charged said surface is presented to said exposure means,
• developing means for applying a liquid developer to said cylinder surface, said developer including toner particles having a negative charge and being dispersed in a volatile carrier liquid, said developing means including a shoe member contoured to said surface of said cylinder for containing the liquid developer in contact across the area of said surface carrying the electrostatic latent image, said shoe member including development electrode means arranged for contact with developer in said shoe member,
• means for applying to said development electrode means a third potential intermediate the first and second potentials whereby the toner particles in the liquid developer are attracted to the image areas on said photoreceptor surface and repelled from the non-image areas of said surface,
• means guiding said web into contact with said surface at a region past said developing means in the direction of rotation of said cylinder,
• means for transferring the toner particles from the latent image and at least part of the carrier liquid onto the web,
• fusing means for directing streams of air heated to above the vaporization temperature of the carrier liquid onto the surfaces of the moving web material to fuse transferred toner particles to the web material and to vaporize the carrier liquid on the web material,
• means for cooling the web exiting said fusing means, and
• delivery means for gathering the web with the printed images fused thereto.

An electrostatic printing press for printing a succession of images on print receiving material, comprising

• supply means and delivery means supported in spaced relation and means for driving and guiding print receiving material therebetween along a predetermined path,
• a cylinder having a photosensitive surface and means supporting said cylinder along the processing path in a position to contact said material,
• charging means for creating a uniform electrostatic charge on said cylinder surface at a first high potential,
• exposure means extending transversely of said surface for directing radiant energy onto predetermined discrete non-image areas of about 0.003 inch on said cylinder surface to cause selective dissipation of the charge on such discrete areas thereby to form an electrostatic latent image as dot patterns on said surface, said exposure means being located around said drum from said charging means such that the uniformly charged part of said surface is presented to said exposure means,
• developing means for applying a liquid developer to said cylinder surface, said developer including negatively charged toner particles having a size in the order of 0.003 inch dispersed in a volatile carrier liquid,
• said developing means including a shoe member contoured to said surface of said cylinder for containing the liquid developer in contact with a predetermined area of said cylinder carrying the electrostatic latent image,
• said shoe member including development electrode means arranged for contact with developer in said shoe member,
• means for applying to said development electrode means a potential in the order of 200 to 600 Volts whereby the toner particles in the liquid developer are attracted to the image areas on said cylinder surface and repelled from the non-image areas of said cylinder surface;
• the improvement comprising
• said driving means including a line shaft coupled to said supply means, said delivery means, and said cylinder for rotating said cylinder such that said surface has a peripheral velocity and direction corresponding to movement of the material,
• means for generating latch pulses at a rate equal to the peripheral velocity of said cylinder in inches /second times 300 whereby resolution around said cylinder at least equals resolution of said exposure means across said cylinder,
• means for supplying imaging data to said exposure means under the control of said means for generating latch pulses.

A web printing press for printing a succession of images on a web, comprising

• web supply means and delivery means supported in spaced relation and means for driving and guiding web material therebetween along a predetermined path,
• a cylinder having a photoreceptor surface and means supporting said cylinder along the processing path in a position to contact said web material,
• means for rotating said cylinder such that said surface has a peripheral velocity and direction corresponding to movement of the web material,
• charging means for creating a uniform electrostatic charge on said photoreceptor surface at a first high potential,
• exposure means extending transversely of said surface for directing discrete beams of radiant energy at a resolution in the order of at least 300 per inch selectively onto predetermined discrete non-image pixel areas on said surface to cause selective dissipation of the charge on such discrete areas to a second low potential, thereby to form an electrostatic latent image on said surface, said exposure means being located around said drum from said charging means so a uniformly charged said surface is presented to said exposure means,
• developing means for applying a liquid developer to said cylinder surface, said developer including toner particles having a negative charge and being dispersed in a volatile carrier liquid, said developing means including a shoe member contoured to said surface of said cylinder for containing the liquid developer in contact across the area of said surface carrying the electrostatic latent image, said shoe member including development electrode means arranged for contact with developer in said shoe member,
• means for applying to said development electrode means a third potential intermediate the first and second potentials whereby the toner particles in the liquid developer are attracted to the image areas on said photoreceptor surface and repelled from the non-image areas of said surface,
• means guiding said web into contact with said surface at a region past said developing means in the direction of rotation of said cylinder,
• means for transferring the toner particles from the latent image and at least part of the carrier liquid onto the web,
• fusing means for directing streams of air heated to above the vaporization temperature of the carrier liquid onto the surfaces of the moving web material to fuse transferred toner particles to the web material and to vaporize the carrier liquid on the web material,
• means for cooling the web exiting said fusing means, and
• delivery means for gathering the web with the printed images fused thereto.

In an electrostatic web printing press for printing a succession of images on a web of print receiving material including

• supply means and delivery means supported in spaced relation,
• means for driving a web between said supply means and said delivery means along a predetermined printing path including an adjustable speed controller,
• a cylinder, having a photoreceptor surface, supported along the printing path in a position to contact said material,
• said driving means rotating said cylinder such that said surface has a peripheral velocity and direction corresponding to movement of the web,
• charging means for creating a uniform electrostatic charge on said surface at a first high voltage,
• a digital exposure means including an array of closely spaced LEDs extending transversely of said surface for directing separate beams of light onto predetermined non-image pixel areas on the charged cylinder surface to cause selective dissipation of the charge on such areas to a second low potential, thereby to form an electrostatic latent image on said surface;
• driving circuits for said LEDs to switch each LED on and off at a rate greater than the velocity of the photoreceptor surface past said exposure means, said driving circuits including individual control circuits for selectively operating said driving circuits according to digital imaging data,
• developing means for applying a developer to the latent image, said developer including toner particles having a negative charge,
• said developing means including a shoe member contoured to said surface of said cylinder for containing the developer in contact with a predetermined area of said cylinder carrying the electrostatic latent image and providing a development electrode means for developer in said shoe member,
• means for applying to said development shoe a third potential intermediate the first and second potentials whereby the toner particles are attracted to the image areas on said cylinder surface and repelled from the non-image areas of said cylinder surface,
• said speed controller including voltage level adjustment means for increasing said first, second and third potentials, and for adjusting said driving circuits to increase the driving current to the LEDs with increase in press operating speed.

In an electrostatic web printing press for printing a succession of images on a web of print receiving material including

• supply means and delivery means supported in spaced relation;
• means for driving a web between said supply means and said delivery means along a predetermined printing path including an adjustable speed controller;
• a plurality of electrostatic printing engines arranged along the path to print images successively on the web, each said printing engine having
• a) a cylinder, having a photoreceptor surface, supported along the printing path in a position to contact said material,
• b) charging means for creating a uniform electrostatic charge on said surface at a first high electrical potential,
• c) a digital exposure means including an array of closely spaced LEDs extending transversely of said surface for directing separate beams of light onto predetermined non-image pixel areas on the charged cylinder surface to cause selective dissipation of the charge on such areas to a second low potential, thereby to form an electrostatic latent image on said surface,
• d) driving circuits for said LEDs to switch each LED on and off at a rate greater than the velocity of the photoreceptor surface past said exposure means, said driving circuits including individual control circuits for selectively operating said driving circuits according to digital imaging data,
• e) developing means for applying a developer to the latent image, said developer including toner particles having a negative charge, said developing means including a shoe member contoured to said surface of said cylinder for containing the developer in contact with a predetermined area of said cylinder carrying the electrostatic latent image and providing a development electrode means for developer in said shoe member.
• f) means for applying to said development shoe a third potential intermediate the first and second potentials whereby the toner particles are attracted to the image areas on said cylinder surface and repelled from the non-image areas of said cylinder surface, and
• g) means for transferring developed images from said surface to the web;
• said driving means rotating said cylinders in synchronism and such that said surfaces have a peripheral velocity and direction corresponding to movement of the web,
• said speed controller including voltage level adjustment means for increasing said first, second and third potentials, and for adjusting said driving circuits to increase the driving current to the LEDs, with increase in press operating speed.

In an electrostatic web printing press for printing a succession of images on a web of print receiving material including

• supply means and delivery means supported in spaced relation;
• means for driving a web between said supply means and said delivery means along a predetermined printing path including an adjustable speed controller;
• a plurality of electrostatic printing engines arranged along the path to print images successively on the web, each said printing engine having
• a) a cylinder, having a photoreceptor surface, supported along the printing path in a position to contact said material,
• b) charging means for creating a uniform electrostatic charge on said surface,
• c) a digital exposure means including an array of closely spaced LEDs extending transversely of said surface for directing separate beams of light onto predetermined pixel areas on the charged surface to cause selective dissipation of the charge on such areas, thereby to form an electrostatic latent image on said surface,
• d) driving circuits for said LEDs to switch each LED on and off at a rate greater than the velocity of the photoreceptor surface past said exposure means, said driving circuits including individual control circuits for selectively operating said driving circuits according to digital imaging data,
• e) developing means for applying a developer including toner particles to the latent image, said developing means including a shoe member contoured to said photoreceptor surface for containing the developer in contact with a predetermined area of said surface,
• f) means for applying an electrical potential to said development shoe effective to attract toner particles to the image areas on said surface and to repel toner particles from the non-image areas of said surface, and
• g) means for transferring developed images from said surface to the web;
• said driving means rotating said cylinders in synchronism and such that said surfaces have a peripheral velocity and direction corresponding to movement of the web,
• fusing means supported along said path downstream from said printing engines and operating to fuse all transferred toner particles to the web.

In an electrostatic web printing press for printing a succession of images on a web of print receiving material including

• supply means and delivery means supported in spaced relation;
• means for driving a web between said supply means and said delivery means along a predetermined printing path including an adjustable speed controller;
• a plurality of electrostatic printing engines arranged along the path to print images successively on the web, each said printing engine having
• a) a cylinder, having a photoreceptor surface defining an image area, supported along the printing path in a position to contact said material,
• b) charging means for creating a uniform electrostatic charge on said surface,
• c) exposure means for directing separate beams of light onto predetermined pixel areas of the image area on the charged surface along bands extending transversely of said surface to cause selective dissipation of the charge on such areas in digital fashion, thereby to form an electrostatic latent image on said surface within the image area,
• d) driving circuit means for said exposure means to switch said exposure means at a rate greater than the velocity of the photoreceptor surface past said exposure means, said driving circuits including register circuits for selectively operating said driving circuit means according to digital imaging data for a line of pixel areas,
• e) developing means for applying a developer including toner particles to the latent image, f) means for transferring developed images from said surface to the web;
• g) an encoder driven in synchronism with said cylinder and generating a string of latch pulses per each cylinder revolution identifying lines of pixel areas across said image area,
• said driving means rotating said cylinders in synchronism and such that said surfaces have a peripheral velocity and direction corresponding to movement of the web,
• fusing means supported along said path downstream from said printing engines and operating to fuse all transferred toner particles to the web,
• a plurality of data interface units, one for each printing engine, including memory means for holding digital image information,
• means for transferring image information from said data interface units to said register circuits of the corresponding printing engines on a line-by-line basis, and
• means for driving said exposure means of each printing engine at a rate dependent upon the output of the corresponding encoder.

In an electrostatic web printing press for printing a succession of images on a web of print receiving material including

• supply means and delivery means supported in spaced relation;
• means for driving a web between said supply means and said delivery means along a predetermined printing path including an adjustable speed controller;
• an electrostatic printing engine arranged along the path to print images successively on the web, said printing engine having
• a) a cylinder, having a photoreceptor surface defining an image area, supported along the printing path in a position to contact said material,
• b) charging means for creating a uniform electrostatic charge on said surface,
• c) exposure means for directing separate beams of light onto predetermined pixel areas of the image area on the charged surface along bands extending transversely of said surface to cause selective dissipation of the charge on such areas in digital fashion, thereby to form an electrostatic latent image on said surface within the image area,
• d) driving circuit means for said exposure means to switch said exposure means at a rate greater than the velocity of the photoreceptor surface past said exposure means, said driving circuits including register circuits for selectively operating said driving circuit means according to digital imaging data for a line of pixel areas,
• e) developing means for applying a developer including toner particles to the latent image,
• f) means for transferring developed images from said surface to the web;
• g) an encoder driven in synchronism with said cylinder and generating a string of latch pulses per each cylinder revolution identifying lines of pixel areas across said image area,
• said driving means rotating said cylinder in synchronism and such that said surface has a peripheral velocity and direction corresponding to movement of the web,
• fusing means supported along said path downstream from said printing engine and operating to fuse all transferred toner particles to the web,
• a data interface unit including memory means for holding digital image information,
• means for transferring image information from said data interface unit to said register circuits on a line-by-line basis, and
• means for driving said exposure means at a rate dependent upon the output of the corresponding encoder.

In a web printing press for printing a succession of images on a web of print receiving material including

• supply means and delivery means supported in spaced relation;
• means for driving a web between said supply means and said delivery means along a predetermined printing path including an adjustable speed controller;
• a printing engine arranged along the path to print images successively on the web, said printing engine having
• a) a cylinder, having a receptor surface defining an image area, supported along the printing path in a position to contact said material,
• b) exposure means for modifying predetermined pixel areas of the image area bands extending transversely of said surface in digital fashion to form a latent image on said surface within the image area,
• c) driving circuit means for said exposure means to switch said exposure means at a rate greater than the velocity of the receptor surface past said exposure means, said driving circuits including register circuits for selectively operating said driving circuit means according to digital imaging data for a line of pixel areas,
• d) means for developing and transferring the images from said surface to the web;
• e) an encoder driven in synchronism with said cylinder and generating a string of latch pulses per each cylinder revolution identifying lines of pixel areas across said image area,
• said driving means rotating said cylinder in synchronism and such that said surface has a peripheral velocity and direction corresponding to movement of the web,
• a data interface unit including memory means for holding digital image information, said memory means being divided into a fixed image memory section and a variable image memory section,
• means for combining the digital image information from each memory section into composite image data and transferring the composite image information from said data interface unit to said register circuits on a line-by-line basis.

The method of printing images on a moving web directly from digital image data, comprising the steps of

• a) providing a refreshable receptor area on a drum surface and guiding a web into position for transfer of images developed on the receptor area successively onto the web,
• b) transporting the web and rotating the drum in synchronism,
• c) storing digitized basic image data into a first memory,
• d) storing digitized variable image data into a second memory,
• e) reading the stored image data simultaneously and synchronously into registers, then during each drum revolution
• f) creating a developed image on the receptor area during each drum revolution using the combined image data in the registers,
• g) transferring the developed image to the web,
• h) preparing the receptor area for the creation of a new image.

A method for printing a succession of images on a web of print receiving material including

• a) driving a web between a web supply station and a web delivery station along a predetermined printing path at adjustable speeds;
• b) providing a refreshable photoreceptor surface on a drum and guiding the web into position for transfer of images developed on the photoreceptor surface successively onto the web, and rotating the drum in synchronism with the web speed;
• then during successive revolutions of the drum
• c) creating a uniform electrostatic charge on the surface;
• d) exposing predetermined pixel areas of the charged surface to individual closely spaced light beams along bands extending transversely of such surface with an array of light beam generators, such as closely packed LEDs, to cause selective reduction of the surface charge at such pixel areas in digital fashion, thereby forming line-by-line an electrostatic latent image on the photoreceptor surface;
• e) providing register circuits for holding digital imaging data for a line of pixel areas,
• f) generating a string of latch pulses per each drum revolution to identify the circumferential location of lines of pixel areas across the photoreceptor surface and selectively switching on/off the individual light beam generators of the array during step (d) at a rate dependent upon the drum velocity and according to data held in the register circuits,
• g) applying a developer including toner particles to latent image;
• h) transferring developed images from the photoreceptor surface to the web;
• i) fusing all transferred toner particles to the web;
• and
• j) cleaning the photoreceptor surface of all residual toner particles after step (h).