Idler roller assembly employing self-securing bearing retainer

A bearing retainer including a flange having a front surface and a rear surface, a hub extending from the front surface and having an exterior surface configured to receive and support a looped extension spring and having an interior forming a bearing pocket, and at least one resilient finger initially extending from the rear surface and having a curve so as to extend toward and beyond the front surface and including at least one retainer tab extending from a surface opposite the hub and positioned on the rear surface side relative to the flange. The resilient finger is configured to be deflectable from a free position toward the hub in response to a deflection force to enable a portion of the resilient finger including the retainer tab to be inserted through an opening in a wall and to substantially return to the free position upon release of the deflection force such that the wall is held between the retainer tab and rear surface, thereby securing the bearing retainer within the opening.

FIELD OF THE INVENTION

The invention relates generally to the field of imaging, and in particular to an imaging apparatus employing an idler roller system. More specifically, the invention relates to an imaging apparatus with an idler roller assembly employing a self-securing bearing retainer.

BACKGROUND OF THE INVENTION

Light sensitive photothermographic film is used in many applications ranging from photocopying apparatuses to graphic arts to medical imaging systems. For example, laser imagers are widely employed in the field of medical imaging to produce visual representations on photothermographic film of digital image data generated by various scanners, such as magnetic resonance imaging (MRI) scanners and computer tomography (CT) scanners. Laser imagers typically include some type of film supply system, a film exposure system, a film processing system, and a transport system that moves and guides film through the laser imager along a transport path from the supply system and through the exposure and processing systems to an output.

Transport systems generally employ one or more spring-loaded roller sets that form a portion of and transport film along the transport path through the laser imager. Such roller sets typically consist of a urethane coated drive roller and some type of idler roller system including a urethane coated idler roller which is held in contact with the drive roller. One such idler roller system includes a bearing retainer which holds a bearing and fits into and slides in an opening in a side wall of the imaging apparatus. A shaft of the idler roller extends through the bearing and bearing retainer and includes one machined groove, adjacent to the bearing retainer and positioned exterior to the imaging apparatus and one machined shoulder adjacent to the bearing retainer but within an interior of the imaging apparatus. To secure the bearing retainers and shaft within the imaging apparatus, a clip, or e-ring, is installed in the machined grooves on each end of the idler roller shaft.

While such an idler roller system is effective at securing the bearing and idler roller, the use of multiple e-rings and corresponding grooves make it relatively costly to manufacture and the cumbersome nature of installation makes it relatively costly to assemble. In light of the above, there is a need for an improved idler roller system and, in particular, an improved bearing retainer.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a bearing retainer having a reduced number of components so as to decrease manufacturing costs.

Another object of the present invention is to provide a bearing retainer which simplifies installation processes so as to decrease assembly costs.

According to one aspect of the invention, there is provided a bearing retainer. The bearing retainer includes a flange having a front surface and a rear surface, a hub extending from the front surface and having an exterior surface to receive and support a looped extension spring and having an interior forming a bearing pocket, and at least one resilient finger initially extending from the rear surface and having a curve so as to extend toward and beyond the front surface and including at least one retainer tab extending from a surface opposite the hub and positioned on the rear surface side relative to the flange. The resilient finger is configured to be deflectable from a free position toward the hub in response to a deflection force to enable a portion of the resilient finger including the retainer tab to be inserted through an opening in a wall and to substantially return to the free position upon release of the deflection force such that the wall is held between the retainer tab and rear surface, thereby securing the bearing retainer within the opening.

According to once aspect of the invention, the hub includes a spring retainer flange extending radially outward from an end of the hub opposite the front major surface of the flange. According to one aspect of the invention, the hub is positioned so as to limit deflection of the at least one resilient retainer finger from the free position to a distance less than a distance which would cause permanent deformation of the at least one resilient retainer finger.

According to one aspect of the invention, the bearing retainer includes a frame element extending from the rear major surface, wherein the frame element is configured to extend through the opening when the bearing retainer is secured within the opening and is configured with dimensions to provide a sliding fit within the opening.

According to one aspect of the invention, the bearing pocket is configured to receive and hold a bearing via an opening in the rear surface. According to one aspect of the invention, the bearing is configured to receive a shaft via the opening, and wherein the shaft is free to rotate within the bearing.

According to one aspect of the invention, the bearing pocket is configured as a bearing and is configured to receive a shaft via an opening in the rear surface, and wherein the bearing pocket is configured to support the shaft and to allow rotation of the shaft therein.

According to one aspect of the invention, the bearing retainer is formed from a single piece of material. According to one aspect of the invention, the bearing retainer comprises a plastic material. According to one aspect of the invention, the bearing retainer comprises an anti-static polycarbonate.

DETAILED DESCRIPTION OF THE INVENTION

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.

FIG. 1is a block diagram illustrating generally an imaging apparatus30employing a bearing retainer and idler roller assembly according to embodiments of the present invention. Imaging apparatus30includes a media supply system32, an exposure system34, a processing system36, and an output system38. In operation, media supply system32provides an unexposed imaging media, such as film40, to exposure system34along a transport path42(indicated by dashed line). Exposure system34subsequently exposes a desired photographic image on film40based on image data (e.g. digital or analog) to form a latent image of the desired photographic image on film40. In one embodiment, exposure system34comprises a laser imager.

Processing system36receives exposed film40from exposure system34and develops the latent image thereon. In one embodiment, processing system36comprises a thermal processor, such as a drum-type processor, which heats exposed film40to thermally develop the latent image. Processing system36subsequently cools and delivers the developed film along transport path42to output system38(e.g. an output tray, sorter) for access by a user. Imaging apparatus30employs at least one roller set44having a drive roller46and an idler roller assembly48, according to embodiments of the present invention, including an idler roller49which, together with drive roller46form a portion of a transport path42.

FIG. 2is an exploded view of one embodiment of idler roller assembly48according to embodiments of the present invention. In one embodiment, in addition to idler roller49, idler roller assembly48includes a bearing retainer50, a bearing52, and an extension spring54. In one embodiment, bearing retainer50is configured to receive and retain bearing52, which in-turn is configured to receive and enable rotation of a shaft56of idler roller49therein. As will be described in greater detail below, bearing retainer50is further configured to “snap into” and retain itself within an opening58in an endplate59of an imaging apparatus, such as imaging apparatus30, and is configured to engage and be biased by extension spring54so as to maintain contact between idler roller49and drive roller46.

FIGS. 3 and 4respectively illustrate front and rear perspective views of one embodiment of bearing retainer50. Bearing retainer50includes a flange60having a front surface62and a rear surface64. A cylindrical hub66extends from front surface62of flange60. An exterior surface68of hub66serves a spring seat and is configured to receive and hold looped extension spring54. In one embodiment, hub66includes a spring retainer tab70extending radially outward from hub66and which is configured to retain looped extension spring54in a position about exterior surface68of hub66. An interior of hub66forms a bearing pocket72that is configured to receive and hold bearing52. In one embodiment, bearing pocket72is cylindrical in shape and configured to receive an annular or toroidal-shaped bearing52. In one embodiment, bearing pocket72by itself is configured as a bearing for shaft56of idler roller49. In one embodiment, hub66includes an opening74through which shaft56extends when installed within bearing pocket72.

A frame element76extends from rear surface64of flange60and is configured to slideably insert and extend through opening58(seeFIG. 1andFIG. 8below) in endplate59. In one embodiment, as illustrated, frame element76is substantially rectangular in shape and is positioned about a perimeter of bearing pocket72. In one embodiment, frame element76is incrementally smaller in dimension than opening58so as to provide what is generally referred to as a “sliding fit” within opening58.

In one embodiment, bearing retainer50includes first and second resilient fingers80and82. First and second resilient fingers80and82initially extend outward from rear surface64of flange60(seeFIG. 3), then curve and extend forward and beyond the front surface62of flange60(seeFIG. 4). In one embodiment, as illustrated, first and second resilient fingers80and82are positioned radially opposite one another relative to hub66.

First and second resilient fingers80and82each include at least one retainer tab extending outward from a surface opposite hub66. In one embodiment, as illustrated, first resilient finger80includes retainer tabs84and86and second resilient finger82includes retainer tabs88and90. First and second resilient fingers80and82, along with their corresponding retainer tabs, are configured so to be deflectable toward hub66from a normally “free” or non-compressed position where first and second resilient fingers80and82are spaced from hub66. In one embodiment, flange60includes notches83and85into which first and second resilient fingers80and82respectively travel when deflected from their non-compressed position (seeFIG. 5Bbelow).

FIGS. 5A and 5Bare side views of bearing retainer50respectively illustrating first and second resilient fingers80and82in a free position and a deflected position. In one embodiment, as illustrated byFIG. 5A, when in the free position, first and second resilient fingers80and82are substantially parallel to longitudinal axis of hub66. When in the free position, a distance between the outermost points of retainer tabs84and86of first resilient finger80and retainer tabs88and90of second resilient finger82is indicated as D192. With reference toFIG. 5B, in response to compression forces93and94, first and second resilient fingers80and82deflect from the free position toward hub66such that a distance D296between the outermost points of retainer tabs84and86of first resilient finger80and retainer tabs88and90of second resilient finger82is less than distance D192. When compression forces93and94are removed, first and second resilient fingers80and82return to the free position illustrated byFIG. 5A.

In one embodiment, bearing retainer50comprises a plastic material. In one embodiment, bearing retainer50, including flange60, hub66, frame element76, and first and second resilient fingers80and82, is formed from a contiguous piece of material. In one embodiment, bearing retainer50is formed using an electro-static discharging polycarbonate material so as to prevent static build-up during transport of film40along transport path42. In one embodiment, bearing retainer50comprises anti-static acetal plastic.

As typically defined, a material's yield strength or yield point refers to a stress point of the material. Upon application of a stress which is below the yield point, the material will elastically deform and return to its original shape when the applied stress is removed. However, if the yield point is exceeded, some fraction of the deformation will be permanent and non-reversible. In one embodiment, as illustrated byFIG. 5B, as first and second resilient fingers80and82are compressed and travel into corresponding notches83and85in flange60, hub66is positioned and configured to prevent “over-deflection” of first and second resilient fingers80and82so that their yield point is not exceeded during installation of bearing retainer50in opening58of endplate59.

Returning toFIG. 2, idler roller assembly48is illustrated in an exploded view with bearing retainer50illustrated in an un-installed position. In one embodiment, opening58includes notches97and98corresponding to and respectively configured to receive first and second resilient fingers80and82of bearing retainer50and having a distance between outside edges of D3100. It is noted that distance D3100is less than distance D1between the outermost points of retainer tabs84and86of first resilient finger80and retainer tabs88and90of second resilient finger82when in the free position (seeFIG. 5A).

In one embodiment, to assemble idler roller assembly48, idler roller49is positioned such that shaft56extends through opening58. Bearing52is positioned within bearing pocket72inside hub66and bearing retainer50is slid onto shaft56such that shaft56extends through bearing52and opening74in the end of hub66. Compression forces93and94are applied to deflect first and second resilient fingers80and82toward hub66until distance D296between outermost points of retainer tabs84and86and retainer tabs88and90is less than distance D3100between outside edges of notches97and98. Subsequently, first and second resilient fingers80and82are inserted into corresponding notches97and98and frame element76is inserted through opening58until rear surface64of flange60contacts an exterior surface102of endplate59, at which point retainer tabs84and86and88and90have respectively passed through corresponding notches97and98. It is noted that flange60has dimensions exceeding those of a main portion (excluding notches97and98) of opening58.

Compression forces93and94are subsequently removed such that first and second resilient fingers80and82substantially return to the free position so that distance D1between outermost points of retainer tabs84and86and retainer tabs88and90is greater than distance D3100between outside edges of notches97and98. At this point, endplate59is retained between rear surface64of flange60and retainer tabs retainer tabs84,86,88, and90such that bearing retainer50is secured within opening58.

FIGS. 7 and 8respectively show front and rear perspective views of endplate59illustrating bearing retainer50in a secured position within opening58. With reference toFIG. 7, after bearing retainer50is secured within opening58, extension spring54is looped over spring retainer tab70and around exterior surface68of hub. Extension spring54is stretched and retainer loops106and108on opposite ends of extension spring54are hooked over and retained by corresponding anchor posts110and112extending from exterior surface102of endplate59.

As mentioned above, frame element76is configured with a “running” or “sliding” fit within opening58whereby the dimensions of frame element76are incrementally smaller than the dimensions of opening58such that frame element76can move, or slide, within opening58. In one embodiment, for example, frame element76has a clearance relative to opening58ranging from a minimum of 0.05 mm to a maximum of 0.21 mm. As such, after installing extension spring54about exterior surface68of hub66and stretching and coupling extension spring54to anchor posts110and112via retainer loops106and108, extension spring54biases (i.e. pulls) bearing retainer50in a direction toward anchor posts110and112, thereby biasing idler roller49against drive roller46.

With reference toFIG. 7, after installation, first and second resilient fingers80and82extend through corresponding notches97and98so as to be accessible from the exterior side of endplate59. As such, bearing retainer50can be removed from opening58without requiring access to the interior surface of endplate59and, thus, without requiring access to an interior of the imaging apparatus of which roller set44is a part, such as imaging apparatus30. However, after installation about hub66, it is noted that extension spring54prevents compression of first and second resilient fingers80and82, thereby preventing inadvertent removal of bearing retainer50from opening58.

By employing a self-securing bearing retainer, such as bearing retainer50, having integrated resilient fingers with retainer tabs, such as first and second resilient fingers80,82and retainer tabs84,86,88, and90, to secure the bearing retainer to a structure, an idler wheel assembly according to embodiments of the present invention, such as idler roller assembly48eliminates the use of e-rings and the need for corresponding grooves in the idler roller shaft. The self-securing nature of bearing retainer50also makes idler roller assembly48less cumbersome to assemble than conventional idler roller assemblies. As a result, an idler roller system employing a bearing retainer according to embodiments of the present invention has fewer components and is easier and less costly to assemble and manufacture than conventional idler roller assemblies.

PARTS LIST