Patent Application
20100276879
This disclosure relates to paper handling systems, and more specifically, to an improved vacuum transport that holds down and transports media through the print zone of a printer.
A typical vacuum transport configuration is shown in prior art
In U.S. Pat. No. 6,505,030 a vacuum transport is shown that allows for varying air pressure on a sheet responsible to sensed sheet parameters, such as, weight and size with the use of multiple plates in a vacuum plenum and a sensor. This patent is included in its entirety herein by reference.
In ink jet printing, and especially in UV coater printing, the transport hold down function is one part of the printing system that is used to establish and control the critical media print surface to ink jet print head gap in the range of 1.0 mm to ±0.2 mm. This is an extremely tight tolerance, especially over an area that can be two square feet or more. Ordinarily, vacuum transports have traditionally solved this problem localizing vacuum hole patterns and overpowering the system with larger vacuum blowers. However, the flow losses around ‘smaller’ or undersized media can be substantial thereby reducing the vacuum and the vacuum hold down effectiveness. In addition, increasing blower capacity will likely produce higher plenum chamber pressures when ‘full sized’ media is present. Further, media and belt distortion become a concern and transport drag torque will be increased. These result in increased cost, power, noise, environmental disruption, media distortion, drag force variations and overall decreased latitude.
In answer to these problems and disclosed herein is a vacuum transport that includes a belt with an array of holes that align to process direction grooves in a vacuum plenum plate positioned across the top of the vacuum chamber. Sliding aperture plates on the underside of the plenum plate inside the vacuum plenum contain a series of specifically contoured holes and slots to progressively open or shut holes connecting the grooves to the vacuum plenum to control air flow and vacuum pressure in the cross process direction for varying widths of media.
Various of the above-mentioned and further features and advantages will be apparent to those skilled in the art from the specific apparatus and its operation or methods described in the example(s) below, and the claims. Thus, they will be better understood from this description of these specific embodiment(s), including the drawing figures (which are approximately to scale) wherein:
While the disclosure will be described hereinafter in connection with a preferred embodiment thereof, it will be understood that limiting the disclosure to that embodiment 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.
The disclosure will now be described by reference to a preferred embodiment ink jet printing apparatus that includes a method and apparatus that minimizes flow losses with smaller media.
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.
Referring now to printer 10 in
The ink jet printer 10 includes a first conveyance path 18 that extends from the leading end portion of the paper supply of the paper supply cassette 12 and leads to a recording section 16, which conducts image recording on the paper P. Plural fist conveyance roller pairs 20 that constrain and convey the paper P to the recording section 16 are disposed on the first conveyance path 18.
The inkjet printer 10 also includes a second conveyance path 24 that extends upward from the recording section 16 and leads to a paper discharge tray 22, which accommodates the paper P on which an image has been recorded. Plural secondary roller pairs 26 that convey the paper P to the paper discharge 22 are disposed on the second conveyance path 24. An inverse conveyance path 36 for conducting two sided printing connects the second conveyance path 24 to the first conveyance path 18.
In operation, the paper P is removed from the paper supply cassette 12 by the feed roll 14, conveyed on the first conveyance path 18 by the plural conveyance roller pairs 20, and fed to the recording section 16, where image recording is conducted. When an image has been recorded on the paper P, the paper P is conveyed on the second conveyance path 24 by the plural conveyance roller pairs 26 and discharged into the paper discharge tray 22. When two-sided printing is to be conducted, an image is first recorded on one side of he paper P, and then the paper P is inverted at the junction 35 of paths 24 and 36 and is conveyed from the second conveyance path 24 to the first conveyance path 18 via the inverse conveyance paper path 36 and is again fed to the recording section 16, where image recording is conducted on the other side of the paper P. Thus, successive image recording is conducted.
The recording section 16 includes an endless conveyor belt 32 that includes a number of small holes (not shown) therein is wound around a drive roller 28 disposed upstream in the paper conveyance direction and a driven roller 30 disposed downstream in the paper conveyance direction. The conveyor belt 32 is configured such that it is circulatingly driven in the direction of arrow A. A nip roller 38 that slidingly contacts the surface of the conveyor belt 32 is disposed on the upper portion of the drive roller 28. A vacuum plenum 50 is positioned inside belt 32 and connected to a vacuum source 54 adapted to apply vacuum pressure to the holes in conveyor belt 32 in order to attach paper P to vacuum platen 52 during recording by the recording section 16.
An ink jet recording head 34 is disposed above the conveyor belt 32. The ink jet recording head 34 is configured to be long, such that its effective recording area is approximately equal to or greater than the cross process direction width of the paper P. The ink jet recording head 34 includes at least four ink jet recording heads 34C, 34M, 34Y and 34K, which respectively, correspond to the four colors Yellow (Y), magenta (M), cyan (C) and black (K). The ink jet recording heads 34C, 34M, 34Y and 34K are disposed along the conveyance direction; thus, the ink jet recording head 34 can record a full-color image.
The ink jet recording head 34 faces a flat portion 32F of the conveyance belt 32, and this facing area serves as an ejection areas to which ink droplets are ejected from the ink jet recording head 34. The paper P conveyed on the first conveyance path 18 is retained and held flat to the conveyor belt flat portion 32F by force of vacuum and sent to the ejection region, where the ink droplets corresponding to the image are ejected from the inkjet recording head 34 and onto the paper P in a state where the paper P faces the ink jet recording head 34.
Ink tanks 40C, 40M, 40Y and 40K, which supply the inks to the ink jet recording heads 34C, 34M, 34Y and 34K are disposed above the ink jet recording head 34.
The ink jet recording heads 34C, 34M, 34Y and 34K are connected to a recording head controller 45. The recording head controller 45 controls the ink jet recording head 34 by determining the ejection timing of the ink droplets and the processing liquid, and the ink ejection ports or nozzles to be used, in accordance with image information, and inputting a drive signal to the ink jet recording heads 34C, 34M, 34Y and 34K.
In accordance with the present disclosure and shown in
It should now be understood that a vacuum transport system has been disclosed that employs a movable shutter valve which works in conjunction with a plenum plate of a vacuum plenum in order to enable cross process direction customization of active areas of a vacuum belt that is in communication with the plenum plate for a vacuum hold down transport of media and thereby minimize flow losses with smaller sized media. In addition, the system reduces noise, lowers power requirements, reduces unit manufacturing cost and lowers energy consumption. Further, more consistent media hold down across a wide range of media sizes is accommodated, as well as, increased system latitude.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
