The invention relates generally to the field of imaging, and in particular to an imaging apparatus employing a sheet turnaround assembly. More specifically, the invention relates to an imaging apparatus with a sheet turnaround assembly employing drive wheels and belts to introduce a high-degree in a sheet transport path following a processing system.
Light sensitive photothermographic film is used in many applications, ranging from a standard photography apparatus to graphic arts to medical imaging systems. Photothermographic film generally includes a base material, such as a thin polymer or paper, coated generally on one side with an emulsion of heat sensitive material. After the emulsion has been subjected to photostimulation (i.e. exposed), the resulting latent image is developed through application of heat to the film.
Several types of photothermographic imaging systems have been developed. For example, laser imagers are widely used in the medical imaging field to produce visual representations on film of digital image data generated by magnetic resonance (MR), computed tomography (CT), and other types of scanners. Laser imagers typically include a media supply system, a laser exposure system, a processing system, and an output system.
In operation, the media supply system provides a sheet of unexposed photothermographic film along a transport path to the laser exposure unit, which exposes a desired latent image in the emulsion. The exposed sheet is then moved along the transport path to the processing system which develops the exposed sheet though application of heat. The developed sheet is then moved along the transport path to the output system (e.g. a tray or a sorter) for access by a user. To create a compact system, the components of the laser imager are often arranged in a vertical fashion with the media supply system being positioned at the bottom and the output system being positioned on top of the unit. In such systems, a turnaround assembly is often employed to introduce a high degree turn (e.g. 180-degrees) in the transport path and direct the sheet from the processing system to the output system on top of the laser imager.
One conventional turnaround assembly employs at least one curved media guide to form the turn in the transport path. Driven roller pairs are positioned at the leading and trailing edges of the media guide, and sometimes along the length of the turn when multiple media guides are employed, to drive sheets through the turn to the output system. While such turnaround systems are generally effective at turning sheets along the transport path, the sheets can sometimes be scratched as they slide along the media guides and cause undesirable visual artifacts in the image. Additionally, the need for both media guides and driven roller pairs adds cost to the imaging system.
As such, while such systems may have achieved certain degrees of success in their particular applications, there is a need to provide an improved turnaround assembly.
An object of the present invention is to provide a cost-effective sheet turnaround assembly that introduces a high-degree turn in a sheet transport path following a processing system without damaging or otherwise causing defects in a developed sheet of imaging media.
Another object of the present invention is to provide a turnaround assembly which does not employ curved media guides for directing sheets of imaging media.
These objects are given only by way of illustrative example, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objectives and advantages inherently achieved by the disclosed invention may occur or become apparent to those skilled in the art. The invention is defined by the appended claims.
According to one embodiment, there is provided a sheet turnaround assembly including a drive shaft positioned laterally across a transport path from a processing system, a plurality of drive wheels axially coupled to and positioned in a spaced fashion along the drive shaft, and a plurality of continuous belts, one belt corresponding to each drive wheel. Each belt is positioned so that its outside surface is tensioned against and forms a desired wrap angle about the corresponding drive wheel to create an arcuate turnaround path there between extending between input and output nips formed by initial and final points of contact between the belt and the drive wheel. The sheet turnaround is configured to receive a thermally developed sheet of photothermographic imaging media from a thermal processor at the input nip via the transport path. Rotation of the drive wheels by the drive shaft causes the outside surface of each belt to run along the corresponding drive wheel and drive the developed sheet along and expel the developed sheet from the turnaround path at the output nip to an output device after turning the developed sheet from the transport path by an angle substantially equal to the wrap angle.
The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other.
The following is a detailed description of the preferred embodiments of the invention, reference being made to drawings in which the same reference numerals identify the same elements of structure in each of the several figures.
In operation, media supply system 32 provides an individual sheet of unexposed photothermographic imaging media, such as sheet 42, along a transport path 44 to exposure system 34. Exposure system 34 subsequently exposes a desired image on sheet 42 based on data representative of the desired image (e.g. digital or analog) to form a latent image of the desired image on sheet 42. In one embodiment, exposure system 34 comprises a laser exposure unit which exposes the latent image on sheet 42 via image data-based modulation of a laser scanning module. Exposed sheet 42 is moved along transport path 44 to processing system 36 which heats exposed sheet 42 to thermally develop the latent image. In one embodiment, processing system 36 comprises a drum and flatbed type thermal processor, such as that described by U.S. patent application Ser. No. 11/029,592. Turnaround assembly 40 receives and drives developed sheet 42 from transport path 44 along an arcuate turnaround path 46 so as to provide a high-degree turn and expel developed sheet 42 to output system 38, which receives and stores one or more developed sheets for access by a user of imaging apparatus 30. An example of an imaging apparatus similar to that described above by imaging apparatus 30 and suitable to be configured for use with output system 38 according to embodiments of the present invention is described by U.S. Pat. No. 6,007,971 to Star et al., which is herein incorporated by reference.
As will be described in greater detail below, according to one embodiment, turnaround assembly 40 includes a driven shaft positioned laterally across transport path 44, a plurality of drive wheels are axially coupled to and positioned in a spaced fashion along the drive shaft, and a plurality of belts, one belt corresponding to each drive wheel. Each belt is positioned so that its outside surface is tensioned against and forms a desired wrap angle about the corresponding drive wheel to create arcuate turnaround path 46 there between and which extends between input and output nips formed by initial and final points of contact between the belt and the drive wheel.
Turnaround assembly 40 is configured to receive a sheet at the input nip from transport path 44. Rotation of the drive wheels by the driven shaft causes the outside surface of each belt to travel along the corresponding drive wheel and drive the sheet along arcuate turnaround path 46 from the input nip to the output nip, where the sheet is expelled from turnaround assembly 40, such as to output system 39, for example. As such, turnaround assembly is configured to turn and redirect a sheet from the transport path by an angle substantially equal to the wrap angle of the belts about their corresponding drive wheel.
Turnaround assembly 40 includes a drive shaft 60 which is rotatably coupled between endplates 52 and 54 and positioned laterally across and substantially parallel to transport path 44 extending at least from drum type processor 48 to turnaround assembly 40. Drive wheels 62, 64, and 66 are coupled to and positioned in a spaced fashion along drive shaft 60 and, thus, in a spaced fashion relative to transport path 44. A motor 68 is coupled to and drives drive shaft 60 via a drive belt 70.
In one embodiment, as illustrated by
A continuous turnaround belt 86a is stretched and looped about idler wheels 80a, 82a, and 84a such that an inside surface contacts and rides on idler wheels 80a, 82a, and 84a and an outside surface wraps around a portion of and rides on drive wheel 62. Similarly, a continuous turnaround belt 86b is stretched and looped about idler wheels 80b, 82b, and 84b such that an inside surface contacts and rides on idler wheels 80b, 82b, and 84b and an outside surface wraps around a portion of and rides on drive wheel 64, and a continuous turnaround belt 86c is stretched and looped about idler wheels 80c, 82c, and 84c such that an inside surface contacts and rides on idler wheels 80c, 82c, and 84c and an outside surface wraps around a portion of and rides on drive wheel 64.
As illustrated by
In operation, motor 68, via drive belt 70 and drive shaft 60, turns drive wheel 64 (and also drive wheels 62 and 66) in a direction as indicated by rotational arrow 100. Because of the tensioning of turnaround belt 86b against drive wheel 64, as drive wheel 64 is driven, the outside surface of turnaround belt 86b moves with drive wheel 64 and turnaround belt 86b is driven in a loop about idler wheels 80b, 82b, and 84b, as indicated by directional arrow 102, with idler wheels 80b, 82b, and 84b respectively spinning about corresponding stationary idler shafts 72, 74, and 76.
In one embodiment, transport path 44 of processing system 36 is formed, at least in part, by a pair of output nip rollers 96 and a media guide 98. Input nip 92 is positioned so as to receive developed sheet 42 from transport path 44 via media guide 98. When a developed sheet of imaging media, such as developed sheet 42, is received from transport path 44, the rotation of drive wheel 64 and turnaround belt 86b draws a leading edge 104 of developed sheet 42 into input nip 92 and drives developed sheet 42 along arcuate turnaround path 46 until a trailing edge 106 is expelled from output nip 94 and developed sheet 42 is delivered to output tray 50.
By engaging and transporting developed sheet 42 along arcuate turnaround path 46 in this fashion, turnaround assembly 40 turns developed sheet 42 by a turnaround angle relative to transport path 44 which is substantially equal to desired wrap angle 88. In one embodiment, idler shafts 72, 74, and 76 and corresponding idler wheels 80b, 82b, and 84b are positioned so that turnaround belt 86b forms a desired wrap angle 88 of at least 120-degrees about drive wheel 64. In one embodiment, turnaround belt 86b forms a desired wrap angle 88 greater than 180-degrees.
In one embodiment, while developed sheet 42 is engaged by output nip rollers 96 of processing system 36, motor 68 turns drive wheels 62, 64, and 66 at a first transport rate which is substantially equal to the transport rate of output nip rollers 96. Subsequently, after trailing edge 106 of developed sheet 42 has passed through output nip rollers 96, motor 68 turns drive wheels 62, 64, and 66 at a second transport rate which is greater than the first transport rate.
In one embodiment, sheet 42 comprises a photothermographic film having an image side (e.g. an emulsion of heat sensitive material) which contacts the outside surface of turnaround belt 86b as developed sheet 42 travels along arcuate transport path 46 from input nip 92 to output nip 94. In one embodiment, turnaround belt 86b (and turnaround belts 86a and 86c) is formed with its outside surface as smooth as possible so as not to scratch or otherwise damage (e.g. cause indentations) the image or emulsion side of developed sheet 42.
In one embodiment, turnaround belt 86b is a seamless belt. In one embodiment, turnaround belt 86b is formed from a urethane material using spin-casting techniques. In one embodiment, turnaround belt 86b is formed so at to have anti-static properties. In one embodiment, turnaround belt 86b is formed with anti-static particles, such as carbon particles, in the urethane material. By having anti-static properties, artifact causing debris is less likely to cling to and accumulate on the outer surface of turnaround belt 86b.
Additionally, it is noted that if turnaround belt 86b is stretched too far, the tension of turnaround belt 86b against drive wheel 64 may be too great and cause defects (e.g. indentations) in developed sheet 42. However, if not stretched far enough, turnaround belt 86b may not provide enough tension against drive wheel 64 to adequately engage developed sheet 42. In one embodiment, turnaround belt 86b has a stretched length which is within a range that is between 1% and 8% greater than its unstretched or relaxed length. In one embodiment, turnaround belt 86b has a stretched length of approximately 385 millimeters and a relaxed length of approximately 372 millimeters (i.e. approximately 3.5% greater).
In one embodiment, idler wheels 80a-80c, 82a-82c, and 84a-84c are retained within corresponding grooves in stationary idler shafts 72, 74, and 76. In one embodiment, idler wheels 80a-80c, 82a-82c, and 84a-84c are formed using an anti-static acetal material. In one embodiment, idler wheels 80a-80c, 82a-82c, and 84a-84c are crowned so that corresponding turnaround belts 86a-86c track and remain centered on idler wheels 80a-80c, 82a-82c, and 84a-84c and on drive wheels 62, 64, and 66. An example of an idler wheel and idler shaft suitable to be configured for use as idler wheels 80a-80c, 82a-82c, and 84a-84c and idler shafts 72, 74, and 76 is described by U.S. patent application Ser. No. 11/502,095 and entitled “Idler Wheel Assembly”, which is assigned to the same assignee as the present invention and incorporated herein by reference.
Although
In one embodiment, drive wheels 62, 64, and 66 are formed or molded from a plastic material. In one embodiment, drive wheels 62, 64, and 66 are molded from an anti-static acetal material. In one embodiment, the circumference of center drive roller 64 is covered or coated with a rubber material so as to better engage and drive developed sheet 42.
Although illustrated by
In summary, by employing turnaround belts 86a-86c tensioned against and traveling over drive wheels 62-66, as described above, turnaround assembly 40 introduces a high-degree turn in the sheet transport path to direct a developed sheet of imaging media from a processing system to an output system without employing curved media guides. As such, turnaround assembly 40 provides a high-degree turn to a developed sheet of imaging media without introducing scratches or other defects associated with guide plates, thereby improving image quality. Turnaround assembly 40 is also cost effective, as guide plates are not required, and is lighter in weight relative to turnaround assemblies employing roller pairs and guide plates.
A computer program product may include one or more storage medium, for example; magnetic storage media such as magnetic disk (such as a floppy disk) or magnetic tape; optical storage media such as optical disk, optical tape, or machine readable bar code; solid-state electronic storage devices such as random access memory (RAM), or read-only memory (ROM); or any other physical device or media employed to store a computer program having instructions for controlling one or more computers to practice the method according to the present invention.
The invention has been described in detail with particular reference to a presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.