Presstek, Inc.

Other

Presst, Inc.

Frank G Pensavecchia

John F Kline

Richard A Williams

John P Gardiner

Thomas E Lewis

Michael T Nowak

Kenneth T Robichaud

Stephen M LaPonsey

John Gary Sousa

James R Moss

Douglas D Fuller

Lawrence J Carme

Keith V Robb

Lawrence A Howard

C Roth Benson

Apparatus and methods for imaging lithographic plates using laser devices that emit in the near-infrared region, and plates suitable for imaging with the apparatus and methods. Laser output either ablates one or more plate layers or physically transforms a surface layer, in either case resulting in an imagewise pattern of features on the plate. The image features exhibit an affinity for ink and/or a fluid to which ink will not adhere that differs from that of unexposed areas.

Laser-driven method and apparatus for lithographic imaging and printing

Apparatus and methods for imaging lithographic plates using laser devices that emit in the near-infrared region, and plates suitable for imaging with the apparatus and methods. Laser output either ablates one or more plate layers or physically transforms a surface layer, in either case resulting in an imagewise pattern of features on the plate. The image features exhibit an affinity for ink or an ink-abhesive fluid that differs from that of unexposed areas.

Laser-imageable lithographic printing members

A plate imaging apparatus and method for imaging a seamless printing member preferably loaded onto a rotating plate cylinder. The plate imaging apparatus moves a writing head in fixed increments in an axial direction relative to the plate cylinder. With the writing head fixed at a first axial position, the imaging apparatus causes a circumferential swath to be imaged onto the seamless printing member commencing from a first starting point. With the plate cylinder still rotating, the imaging apparatus then steps the writing head to the next axial position, thereby defining a second starting point once the writing head is ready to resume imaging that is offset from the first starting point. The imaging apparatus then causes a second circumferential swath to be imaged onto the seamless printing member commencing from the second starting point.

Method and apparatus for imaging a seamless print medium

A plate-imaging system and a plate-cylinder support structure are coupled in a manner that achieves precise spacing between a writing head and the surface of a lithographic plate. The imaging unit is designed to permit the writing head undergo controlled advancement toward the plate cylinder, and includes a pair of rollers fixed with respect to the writing head and a spaced so as to facilitate rolling contact with peripheral segments of the cylinder. When the imaging unit is brought into contact with the structure containing the plate cylinder, the writing head is advanced toward the cylinder until the rollers make contact with the peripheral segments. The alignment between the rollers and the writing head is fixed such that rolling contact between the rollers and the peripheral cylinder segments ensures proper spacing between the writing head and a plate mounted to the plate cylinder. To ensure a constant tangential (linear) rotation velocity of the plate cylinder regardless of its diameter, the plate cylinder is driven with a fixed-diameter drive gear. In this way, the tangential velocity of the plate cylinder is constant and determined by the the pitch diameter of the drive gear.

Lithographic imaging system for interchangeable plate cylinders

Laser guiding and focusing apparatus for imaging lithographic printing members responsive to the output of laser devices. Radiation passes through at least one discrete layer of a printing member and ablates one or more underlying layers, resulting in an imagewise pattern of features on the printing member. The radiation is obtained from a laser diode and its dispersion reduced to produce an image spot with maximum depth-of-focus tolerance.

Apparatus for laser-discharge imaging including beam-guiding assemblies

An automatic plate-loading cylinder maintains circumferential tension of material wrapped around its exterior surface, the tension being both constant and sufficiently high to keep the material in position against tangential forces (due, for example, to rolling contact with a blanket cylinder). The invention can operate by tying the braking torque exerted on the supply or uptake spool to the radius of that spool, thereby compensating for changes in tension that accompany application of a constant torque. The device can include apparatus for dispensing a consistent amount of material from a supply spool without the need to actually measure the material during a payout cycle. In both aspects, the invention exploits the fact that material is both wound and paid out in an Archimedian spiral. Accordingly, knowledge of an initial radius of one of the spools and the amount of material paid out during each advancement cycle facilitates straightforward computation of the number of necessary rotations of either spool (as well as the resulting new spool radius, which is utilized for the next advancement cycle). The same knowledge additionally allows for straightforward computation of the torque required on the tensioning brake.

Automatic plate-loading cylinder with constant circumferential tension

Modular printing apparatus wherein multiple central-impression presses may be linked to one another, either directly or through a perfecting assembly that reverses the facewise orientation of cut sheets. The presses each contain circuitry defining a signal and control path for the press and a plurality of electrical contacts that renders the path accessible and facilitates serial connection of the presses without disruption of the path. At least one of the presses includes a port for receiving connection to a controller, which thereby engages the signal path and, via the path, operates the presses independently or together as appropriate. The system includes a connector that is used to couple the electrical contacts of one press to those of the second press, thereby establishing a single, continuous signal and control path through both presses accessible to the controller. The system can accommodate a perfecting assembly that may be selectably engaged between the presses, and which thereby becomes a part of the system. The perfecting assembly includes circuitry defining a signal and control path for the assembly and sets of of electrical contacts capable of mating with the contacts of two presses and retaining the continuous path.

Modular digital printing press with linking perfecting assembly

Lithographic printing plates for use with laser discharge imaging

In a digital imaging system including an array of imaging devices that image a substrate in a lateral series of adjacent longitudinal swaths, methods and apparatus for correcting device offset and hiding between regions imaged by adjacent devices. Along the direction of imaging (i.e., the dimension along which the imaging device(s) and the substrate move relative to one another during an imaging pass), adjustments take the form of compensating increases or decreases to the normal intervals between discharges to adjacent image points. Transverse to the direction of imaging, the invention compensates for imprecise device orientation and 'seam' artifacts by, first, commencing imaging with the device having the greatest offset from proper orientation, and second, as a fine adjustment, repeating at least one imaging swath to produce intentional transverse overlap between adjacent swaths.

Method and apparatus for correcting and adjusting digital image output

Laser-driven method and apparatus for lithographic imaging

A winding assembly especially suitable for use in conjunction with a system for automated imaging of lithographic plate material, including on-press imaging systems. A feeder spool installed within a plate-support cylinder contains a rolled supply of plate material, which wraps around the cylinder and is received by an uptake spool, also located within the cylinder. The assembly is driven by the same power source used to rotate the plate-support cylinder, and maintains a strong tension along the wrapped material.

Automatic plate-loading cylinder for use with plate-imaging systems

Techniques for imaging lithographic printing members responsive to the output of laser devices. Laser output passes through at least one discrete layer and ablates one or more underlying layers, resulting in an imagewise pattern of features on the printing member. The image features exhibit an affinity for ink or an ink-abhesive fluid that differs from that of unexposed areas.

Method for laser-discharge imaging a printing plate

A method of reducing printing artifacts in a printing apparatus including a plurality of printing plates, each of which is produced by successive scans of an array of imaging devices wherein the printing artifacts are caused by defective operation of one or more of the imaging devices. Printing artifacts are visually minimized by staggering the imaging devices used to produce separation plates. By staggering the imaging devices, the distance between artifacts can be reduced thereby causing the artifact reproduced in the final composite image to be less accentuated.

Growing community of inventors

Hudson, NH, United States of America

Frank G Pensavecchia