Patent Grant
9446612
Devices and methods herein generally relate to machines such as printers and/or copier devices and, more particularly, to gripper architecture for sheet conveyance.
Marking systems that transport paper or other media are well known in the art. These marking systems include electrostatic marking systems, non-electrostatic marking systems, printers, or any other marking system where paper, or other flexible media or sheets, are transported internally.
In printing systems, there exist a variety of systems and methods for handling sheets of different sizes. Some systems convey sheets via systems of belts or rollers, which provide superb flexibility for sheets of different sizes. But, in these systems, slippage between sheets and their conveyance mechanism can create mis-registration between sheets and the printed image that is applied to them.
The gripper-based architecture of traditional offset lithography provides the most robust system for sheet registration. This is because, in a gripper-based architecture, once a sheet is seized in a gripper, it remains rigidly clamped in that gripper (or is passed via a system with high mechanical tolerances to subsequent grippers) until all printing processes are completed.
However, because lithographic systems are based on a master (printing plate) of typically fixed size, lithographic gripper-system architectures are ill suited for adaptation to digital printing systems where sheet size might be variable. While one might propose creation of a system with multiple grippers positioned for multiple sheet lengths, in practice such a system would induce print quality defects for long sheets, the cause of the defects being the unsupported portion of the sheet that bridges the gap where the additional short-sheet grippers are located. Due to the unwanted gap, heretofore, a multiple-gripper-for-multiple sheet-length architecture was not practical. Hence, the cadence of gripping relative to sheet velocity is fixed at a single value.
A principle advantage of digital printing is that small sheets may be printed at a faster rate (commensurate with their length) than larger sheets. But digital architectures have heretofore been unable to enjoy the image-to-paper registration precision characteristics of a gripper system, while maintaining the advantage of efficient rates on smaller sheets. Architectures could achieve registration precision or speed efficiency across sizes, but not both.
Disclosed herein is a modification of the traditional lithographic press architecture to enable multiple points for gripping a sheet. This would provide the time-proven registration advantages of gripper-based architectures, while also achieving efficient print rates for smaller sheet sizes.
According to an apparatus herein, a sheet supply device feeds substrates to a printing system. The apparatus includes an impression cylinder. A first gripper is positioned in a first location on a circumferential wall of the impression cylinder. A second gripper is positioned in a second location on the circumferential wall of the impression cylinder. The second location is angularly spaced apart from the first location around the circumferential wall. A cover selectively covers the second gripper. Responsive to the first gripper gripping an edge of a substrate of a first length supplied from the sheet supply device, the first length being greater than the length of the circumferential arc between the first gripper and the second gripper, the cover provides a smooth curved surface over the second gripper.
According to a sheet registration and conveyance system herein, the system comprises an impression cylinder. A first gripper is positioned in a first location on a circumferential wall of the impression cylinder. A second gripper is positioned in a second location on the circumferential wall of the impression cylinder. The second location is angularly spaced apart from the first location around the circumferential wall. The system includes sheet supply devices supplying first substrates having a first length and second substrates having a second length. The first length is greater than the length of the circumferential arc between the first gripper and the second gripper and the second length is less than the length of the circumferential arc between the first gripper and the second gripper. Responsive to substrates of the second length being supplied, the first gripper grips a leading edge of a first sheet from a sheet supply device and the second gripper grips a leading edge of a second sheet from the sheet supply device. Responsive to substrates of the first length being supplied, the first gripper grips a leading edge of a sheet from the sheet supply device and the cover provides a smooth curved surface over the second gripper.
A printing system herein includes a processor, a marking device operatively connected to the processor, and sheet supply devices. The sheet supply devices supply sheets of a first length and sheets of a second length to the marking device. The marking device comprises an impression cylinder. A first gripper is positioned in a first location on a circumferential wall of the impression cylinder. A second gripper is positioned in a second location on the circumferential wall of the impression cylinder. The second location is angularly spaced apart from the first location around the circumferential wall. A cover selectively covers the second gripper. The processor identifies sheets of the first length or sheets of the second length being fed to the marking device. The first length is greater than the length of the circumferential arc between the first gripper and the second gripper and the second length is less than the length of the circumferential arc between the first gripper and the second gripper. Responsive to the processor identifying sheets of the first length being fed to the marking device, the processor causes the cover to cover the second gripper providing a smooth curved surface over the second gripper. The marking device renders images on the sheets of the first length. The processor outputs the media containing the images.
These and other features are described in, or are apparent from, the following detailed description.
Various examples of the devices and methods are described in detail below, with reference to the attached drawing figures, which are not necessarily drawn to scale and in which:
The disclosure will now be described by reference to a printing apparatus that includes an impression cylinder having more than one set of grippers angularly spaced apart around the circumference of the impression cylinder and having a cover for grippers that are not being used. The cover provides a smooth curved surface over the gripper not being used. While the disclosure will be described hereinafter in connection with specific devices and methods thereof, it will be understood that limiting the disclosure to such specific devices and methods is not intended. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.
For a general understanding of the features of the disclosure, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements.
The term ‘printer’, ‘printing device’, ‘reproduction apparatus’, or ‘imaging apparatus’ as used herein broadly encompasses various printers, copiers, or multifunction machines or systems, xerographic, lithographic, inkjet, or otherwise, unless otherwise defined in a claim. The term ‘sheet’ or ‘substrate’ herein refers to any flimsy physical sheet of paper, plastic, or other useable physical substrate for printing images thereon, whether precut or initially web fed. A compiled collated set of printed output sheets may be alternatively referred to as a document, booklet, or the like. It is also known to use interposers or inserters to add covers or other inserts to the compiled sets.
Referring to the
The printing device 101 may include at least one marking device 122 (sometimes referred to as print engines) operatively connected to the controller/processor 104. A media transportation path 125 is positioned to supply sheets of printable media from a media supply 128 (that includes paper trays media size sensors connected to the controller/processor 104) to the marking device(s) 122, etc., along the media transportation path 125. After receiving various markings from the printing engine(s), the sheets of media can optionally pass to a finisher 131 which can fold, staple, sort, etc., the various printed sheets.
Further, the marking device 122 is any device capable of rendering an image. The set of marking devices includes digital document reproduction equipment and other copier systems as are widely known in commerce, photographic production and reproduction equipment, monitors and other displays, computer workstations and servers, including a wide variety of color marking devices, and the like.
To render an image is to reduce the image data (or a signal thereof) to viewable form; store the image data to memory or a storage device for subsequent retrieval; or communicate the image data to another device. Such communication may take the form of transmitting a digital signal of the image data over a network.
In addition, the printing device 101 can include one or more accessory functional component (such as a scanner/document handler 134, etc.) that also operates on the power supplied from the external power source 119 (through the power supply 116).
The scanner/document handler 134 may be any image input device capable of obtaining information from an image. The set of image input devices is intended to encompass a wide variety of devices such as, for example, digital document devices, computer systems, memory and storage devices, networked platforms such as servers and client devices which can obtain pixel values from a source device, and image capture devices. The set of image capture devices includes scanners, cameras, photography equipment, facsimile machines, photo reproduction equipment, digital printing presses, xerographic devices, and the like. A scanner is one image capture device that optically scans images, print media, and the like, and converts the scanned image into a digitized format. Common scanning devices include variations of the flatbed scanner, generally known in the art, wherein specialized image receptors move beneath a platen and scan the media placed on the platen. Modern digital scanners typically incorporate a charge-coupled device (CCD) or a contact image sensor (CIS) as the image sensing receptor(s). The scanning device produces a signal of the scanned image data. Such a digital signal contains information about pixels such as color value, intensity, and their location within the scanned image.
The printing device 101 may also include a non-transitory computer storage medium 137 (which can be optical, magnetic, capacitor based, etc.) readable by the controller/processor 104. The non-transitory computer storage medium 137 stores instructions that the controller/processor 104 executes to allow the printing device 101 to perform its various functions, such as those described herein.
It should be understood that the controller/processor 104 as used herein comprises a computerized device adapted to perform (i.e., programmed to perform, configured to perform, etc.) the below described system operations. According to systems and methods herein, the controller/processor 104 comprises a programmable, self-contained, dedicated mini-computer. The details of such computerized devices are not discussed herein for purposes of brevity and reader focus.
Thus, as shown in
Printing devices, such as shown in
As would be understood by those ordinarily skilled in the art, the printing device 101 shown in
In other words, an exemplary imaging system comprises a multifunctional device with print, copy, scan, and fax services. Such multifunctional devices are well known in the art and may comprise print engines based upon liquid or solid ink jet, electrophotography, other electrostatographic technologies, and other imaging technologies. The general principles of imaging are well known to many skilled in the art and are described above as an example of an imaging system to which the present concepts is applicable.
In press operation, a sheet of paper 222 is retained by the grippers 205, 214 and, as the impression cylinder 202 rotates, the sheet of paper 222 is wrapped around the impression cylinder 202 against its circumferential wall 211. In the lithographic printing process, uniform pressure on the sheet of paper 222, applied between the impression cylinder 202 and an inked blanket cylinder 313 (
In
Devices herein disclose a modification of the traditional lithographic press architecture to enable multiple points for gripping a sheet of paper 222. According to devices herein, the mechanical design of at least one of the grippers 205, 214 includes a cover 225, 228. The cover 225, 228 can be selectively disposed such that the gap in the impression cylinder 202 occupied by the gripper not in active use is filled, such that the surface of the impression cylinder 202 in that region is smooth and continuous with the surrounding region. Such modifications provide the time-proven registration advantages of gripper-based architectures, while also achieving efficient print rates for smaller sheet sizes. It is contemplated that this architecture can be used for direct-to-paper inkjet printing, but may also be combined with other marking technologies.
The traditional lithographic method of impression cylinders and grippers enables very high precision image-to-paper registration. But a principal value of digital printing is that, absent a printing plate (of necessarily fixed size), printing sheets of different lengths is readily possible. Devices disclosed herein allow the marriage of these two values i.e., tight registration and variable sheet size.
The devices and methods described herein disclose a sheet conveyance system. The sheet registration and conveyance system includes an impression cylinder 202. A first gripper 205 is positioned in a first location 208 on a circumferential wall 211 of the impression cylinder 202. A second gripper 214 is positioned in a second location 217 on the circumferential wall 211 of the impression cylinder 202. The second location 217 is angularly spaced apart from the first location 208 around the circumferential wall 211. The system includes sheet supply devices, such as media supply 128, supplying first sheets of paper 222 having a first length and second sheets of paper 319 having a second length. The first length is greater than the length of the circumferential arc between the first gripper 205 and the second gripper 214 and the second length is less than the length of the circumferential arc between the first gripper 205 and the second gripper 214. Responsive to substrates of the second length being supplied (i.e., less than the length of the circumferential arc between the first gripper 205 and the second gripper 214), the first gripper 205 grips a leading edge of a first sheet of paper from the media supply 128 and the second gripper 214 grips a leading edge of a second sheet from the media supply 128. Responsive to substrates of the first length being supplied (i.e., greater than the length of the circumferential arc between the first gripper 205 and the second gripper 214), the first gripper 205 grips a leading edge of a sheet from the media supply 128 and the cover 228 provides a smooth curved surface over the second gripper 214.
According to a printing system herein, the printing system includes a controller/processor 104, a marking device, such as transfer station 32, operatively connected to the controller/processor 104, and sheet supply devices, such as media supply 128. The sheet supply devices supply sheets of paper 222 having a first length and sheets of paper 222 having a second length to the marking device. The marking device includes an impression cylinder 202. A first gripper 205 is positioned in a first location 208 on a circumferential wall 211 of the impression cylinder 202. A second gripper 214 is positioned in a second location 217 on the circumferential wall 211 of the impression cylinder 202. The second location 217 is angularly spaced apart from the first location 208 around the circumferential wall 211. A cover 228 selectively covers the second gripper 214. The controller/processor 104 identifies sheets of paper 222 having the first length or sheets of paper 222 having the second length being fed to the marking device. The first length is greater than the length of the circumferential arc between the first gripper 205 and the second gripper 214 and the second length is less than the length of the circumferential arc between the first gripper 205 and the second gripper 214. Responsive to the controller/processor 104 identifying sheets of paper 222 having the first length being fed to the marking device, the controller/processor 104 causes the cover 228 to cover the second gripper 214 providing a smooth curved surface over the second gripper 214. The marking device renders images on the sheets of paper 222 having the first length. The controller/processor 104 outputs the sheets of paper 222 containing the images.
In other words, one of the concepts disclosed is to selectively cover the gap over the unused gripper with a smooth curved surface in order to achieve defect-free printing, while dynamically printing sheets of different lengths.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The descriptions of the various devices and methods of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the devices and methods disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described devices and methods. The terminology used herein was chosen to best explain the principles of the devices and methods, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the devices and methods disclosed herein.
As mentioned above, the terms ‘printer’ or ‘printing device’ as used herein encompasses any apparatus, such as a digital copier, bookmaking machine, facsimile machine, multi-function machine, etc. that performs a print outputting function for any purpose. The devices and methods herein can encompass devices that print in color, monochrome, or handle color or monochrome image data. All foregoing devices and methods are specifically applicable to electrostatographic and/or xerographic machines and/or processes.
The terminology used herein is for the purpose of describing particular devices and methods only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Further, the terms ‘automated’ or ‘automatically’ mean that once a process is started (by a machine or a user); one or more machines perform the process without further input from any user.
In addition, terms such as “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “upper”, “lower”, “under”, “below”, “underlying”, “over”, “overlying”, “parallel”, “perpendicular”, etc., used herein are understood to be relative locations as they are oriented and illustrated in the drawings (unless otherwise indicated). Terms such as “touching”, “on”, “in direct contact”, “abutting”, “directly adjacent to”, etc., mean that at least one element physically contacts another element (without other elements separating the described elements).
It will be appreciated that the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Those skilled in the art may subsequently make various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein, which are also intended to be encompassed by the following claims. Unless specifically defined in a specific claim itself, steps or components of the systems and methods herein should not be implied or imported from any above example as limitations to any particular order, number, position, size, shape, angle, color, temperature, or material.
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