WO2001061418A1

WO2001061418A1 - An electrophotographic imaging system having a support shoe positioned within the laser strike region

Info

Publication number: WO2001061418A1
Application number: PCT/US2000/021089
Authority: WO
Inventors: Bradley B. Rassatt; John D. Watson; Truman F. Kellie; William D. Edwards
Original assignee: Imation Corp.
Priority date: 2000-02-16
Filing date: 2000-08-02
Publication date: 2001-08-23

Abstract

The present invention provides an electrophotographic imaging system (10) for producing a latent image from image data, including a support shoe (56) positioned within a laser strike region (82). The system (10) includes a photoconductor belt (12) capable of movement in a first direction (45) forming a continuous transport path. The photoconductor belt (12) having a first major surface (58) and a second major surface (59). A scanner assembly (24, 26, 28, 30) is provided including a scanner for scanning a laser beam representative of the image data across the first major surface (58) within a laser strike region (82) to produce the latent image. A shoe (56) extends across the second major surface (59). The shoe (56) includes a first curved surface (78) within the laser strike region (82) such that the second major surface (59) contacts the first curved surface (78) while the scanner scans the laser beam across the first major surface (58).

Description

AN ELECTROPHOTOGRAPHIC IMAGING SYSTEM

HAVING A SUPPORT SHOE POSITIONED WITHIN

THE LASER STRIKE REGION

Field of the Invention

The present invention generally relates to imaging systems, and in particular, to an electrophotography imaging system and method having a support shoe positioned within a laser strike region to aid in producing high quality latent images on the photoconductor belt.

Background of the Invention In electrophotography systems, a photoconductor belt travels around a series of rollers defining an imaging transport path. Such an electrophotographic process enables the production of high quality images on a receptor material located on the photoconductor belt. Devices which utilize electrophotography include conventional laser printers, photocopiers, proofers, etc. Conventional electrophotographic systems include both monochrome systems (e.g., a laser printer) and multi-colored systems. In a multi-color electrophotographic imaging system, each of the latent images is formed by scanning a modulated laser beam across the moving photoconductor to selectively alter the charge pattern on the photoconductor in an image-wise pattern. Appropriately colored developers (i.e., liquid inks or toners) are applied to the photoconductor after each latent image is formed to develop the latent images. The resulting color separation images ultimately are transferred to the photoreceptor material to form the multi-color image.

In some electrophotographic imaging systems, the latent images are formed and developed on top of one another in a common imaging region of the photoconductor. The latent images can be formed and developed in multiple passes of the photoconductor around a continuous transport path. Alternatively, the latent images can be formed and developed in a single pass of the photoconductor around the continuous transport path. In monochrome imaging the image should dimensionally be an accurate reproduction of the original. In multi-colored electrophotographic imaging the latent images must be formed in precise registration with one another to produce a high quality image. Precise registration is difficult due to a phenomenon called "troughing". Troughing, also known as "out of plane bending", refers to the undesirable act of wrinkling, sagging, bending, twisting, or torquing of the photoconductor belt and associated photoreceptor in free spaces between the rollers. Troughing of the photoconductor belt in a laser strike or developer regions degrades the overall quality of the final image since portions of the latent images are formed upon the photoreceptor at various undesired angles and curves. Precise registration is also difficult due to deviation of the photoconductor belt from the transport path in a direction perpendicular to the transport path. Specifically, the photoconductor belt can undergo side-to-side movement during travel. The imaging region in which the latent images are formed is commonly fixed relative to the edge of the photoconductor belt. However, the scanning beam used to form each latent image in the imaging region is fixed relative to a start-of-scan coordinate. The side-to-side movement of the photoconductor belt, known as belt walking, can cause movement of the imaging region relative to the start-of-scan coordinate thereby degrading the overall quality of the final image since portions of the latent images are transferred to the photoreceptor at incorrect locations. Further "apparent" belt walking exists due to the belt troughing (e.g., belt sagging, wrinkling) and due to among other reasons out of round or misaligned rollers (e.g., squeegee rollers or squeegee back-up rollers).

As a result, misregistration can occur between different scan lines and between different latent images. This misregistration can significantly degrade image quality. In particular, the misregistration can produce visible artifacts in the final multi-color image upon transfer of the misregistered color separation images to the receptor material. There is a need for an electrophotographic imaging system which minimizes both belt troughing and side-to-side movement of a photoconductor belt during formation of latent images. Summary of the Invention

In one embodiment, the present invention provides an electrophotographic imaging system for producing a latent image from image data. The system includes a photoconductor belt capable of movement in a first direction forming a continuous transport path. The photoconductor belt includes a first major surface and a second major surface. A scanner assembly is provided including a scanner for scanning a laser beam representative of the image data across the first major surface within a laser strike region to produce the latent image. A shoe extends across the second major surface. The shoe includes a first curved surface within the laser strike region such that the second major surface contacts the first curved surface while the scanner scans the laser beam across the first major surface.

The system may further include a developer for developing the latent image on the photoconductor belt within a developing region. The developing region is adjacent the laser strike region. A second curved surface is provided extending longitudinally across the second major surface, wherein the second major surface contacts the second curved surface within the developing region during developing of the latent image on the photoconductor belt. In one aspect, the shoe includes the second curved surface.

In one aspect, the first curved surface is a convex curved surface. The second curved surface is a convex curved surface. The first curved surface has a radius greater than a radius of the second curved surface.

The system may further include a belt position detection system including a photodetector extending across an edge of the photoconductor belt. The photodetector is responsive to a light source for providing a belt edge position detection signal representative of belt position. Preferably, the photodetector is coupled to the shoe. In one aspect, the shoe includes an aperture in the first curved surface in the laser strike region. The aperture extends at least partially through the shoe. The edge of the photoconductor belt extends partially across the aperture. In another aspect, the scanner is in optical alignment with the photodetector. In one aspect, the aperture has a ramp edge having an angled surface relative to a major surface of the photodetector. The angled surface operates to redirect the laser beam incident on the angled surface away from the photodetector and scanner assembly. The scanner scans the laser beam across the edge of the photoconductor belt such that it is incident on the photodetector. A belt steering system is provided including a belt steering mechanism, wherein the belt steering system is responsive to the photodetector for controlling the belt steering mechanism to adjust movement of the photoconductor belt in a direction substantially perpendicular to the first direction. The system may further include a second scanner assembly including a second scanner for scanning a second laser beam representative of the image data across the first major surface within a second laser strike region to produce the latent image. A second shoe is provided extending across the second major surface. The second shoe includes a first curved surface within the laser strike region such that the second major surface contacts the first curved surface while the second scanner scans the second laser beam across the first major surface. In one aspect, at least a portion of the first curved surface is reflective. In another embodiment, the present invention provides an electrophotographic imaging system for producing a latent image from image data. The system includes a photoconductor belt capable of movement in a first direction, forming a continuous transport path, the photoconductor belt having a first major surface and a second major surface. A scanner assembly is provided including a scanner for scanning a laser beam representative of the image data across the first major surface within a laser strike region to produce the latent image. A shoe extends across the second major surface. The shoe includes a first curved surface within the laser strike region such that the second major surface moves across a portion of the first curved surface and the photoconductor belt takes the shape of the first curved surface within the laser strike region while the scanner scans the laser beam across the first major surface. In one aspect, the first curved surface of the shoe is a convex surface, having a first center axis extending longitudinally across the second major surface substantially parallel to the shoe. A developer is provided for developing the latent image on the photoconductor belt within a developing region, wherein the developing region is adjacent the laser strike region. A second curved surface extends longitudinally across the second major surface, wherein the second major surface contacts the second curved surface within the developing region during developing of the latent image on the photoconductor belt. In one aspect, the second curved surface of the shoe is a convex surface, having a second center axis extending longitudinally across the second major surface substantially parallel to the shoe. The system may further include a belt position detection system including a photodetector extending across an edge of the photoconductor belt. The photodetector is responsive to a light source for providing a belt edge position detection signal representative of belt position. The photodetector is coupled to the shoe. The shoe includes an aperture in the first curved surface in the laser strike region. The aperture extends at least partially through the shoe. The edge of the photoconductor belt extends partially across the aperture. The scanner is in optical alignment with the photodetector. The scanner scans the laser beam across the edge of the photoconductor belt such that it is incident on the photodetector. In one aspect, the first curved surface is reflective. In another aspect the present invention provides an electrophotographic imaging system for producing a latent image from image data. The system includes a photoconductor belt capable of movement in a first direction forming a continuous transport path, the photoconductor belt having a first major surface and a second major surface. An image exposure system is provided having a light source for exposing the photoconductor belt representative of the image data across the first major surface within an exposure region to produce the latent image. A shoe extends across the second major surface, including a first curved surface within the exposure region such that the second major surface contacts the first curved surface while the exposure system exposes the image data across the first maj or surface . A developer is provided for developing the latent image on the photoconductor belt within a developing region, wherein the developing region is adjacent the exposure region. A second curved surface extending longitudinally across the second major surface is provided, wherein the second major surface contacts the second curved surface within the developing region during developing of the latent image on the photoconductor belt. In one aspect, the light source is a scanner. In another aspect, the light source is an LED bar.

The system may further include a belt position detection system including a photodetector extending across an edge of the photoconductor belt, wherein the photodetector is responsive to the light source for providing a belt edge position detection signal representative of belt position. In one aspect, the photodetector is coupled to the shoe, wherein the shoe includes an aperture in the first curved surface in the exposure region, the aperture extending at least partially through the shoe, and wherein the edge of the photoconductor belt extends partially across the aperture. In one preferred aspect, the aperture has a ramp edge having an angled surface relative to a major surface of the photodetector, wherein the angled surface operates to redirect the laser beam incident on the angled surface away from the photodetector and image exposure system.

Brief Description of the Drawings Figure 1 is a schematic diagram illustrating one exemplary embodiment of an electrophotographic imaging system, including a plurality of shoes, in accordance with the present invention.

Figure 2 is a perspective, partially exploded view of one exemplary embodiment of a shoe in accordance with the present invention. Figure 3 is a side view illustrating one exemplary embodiment of a shoe positioned within a laser strike region and a developer region, in accordance with the present invention.

Figure 4 is a cross-sectional view illustrating one exemplary embodiment of a portion of a shoe in accordance with the present invention as seen from line 4- 4 of Figure 3. Description of the Preferred Embodiments

In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

Figure 1 is a schematic diagram illustrating one exemplary embodiment of an electrophotographic imaging system 10 including at least one shoe located along a free span in of the photoconductor belt, in accordance with the present invention. Imaging system 10 includes photoconductor belt 12, plurality of rollers 14, 15, 16, 17, 18, grounding brush 19, erasure station 20, charging station 22, an image exposure system including a plurality of scanner assemblies having a plurality of scanners 24, 26, 28, 30, plurality of development stations 32, 34, 36, 38, drying station 40, transfer station 42, and belt steering system 44.

An image exposure system utilizing a scanner assembly is detailed herein. Alternatively, the image exposure system may comprise other light sources for exposing image data across belt 12 (e.g., LED bars, mechanical mirrored exposure systems, or systems utilizing fiber optics). Other image exposure systems suitable for use with the present invention will become apparent to those skilled in the art after reading the present application. Electrophotographic imaging system 10 forms a multi-color image in a single pass of photoconductor belt 12 around a continuous transport path. An imaging system capable of assembling a multi-color image in a single pass of a photoconductor is disclosed, for example, in U.S. Patent No. 5,916,718 to Kellie et al., entitled "Method and Apparatus for Producing a Multi-Colored Image in an Electrophotographic System." Alternatively, a single pass system may be used. In operation of electrophotographic imaging system 10, photoconductor belt 12 is mounted about rollers 14, 15, 16, 17, 18 and travels in a first direction indicated by arrows 45 along the continuous transport path. While five rollers (14, 15, 16, 17, 18) are shown in Figure 1, it is understood that any number of rollers can be used without deviating from the present invention. As photoconductor belt 12 moves along the transport path, erasure station 20 uniformly discharges any charge remaining on the belt from a previous imaging operation. Additionally, grounding brush 19 mechanically couples the photoconductor belt 12 to ground potential. Photoconductor belt 12 then encounters charging station 22, which uniformly charges a portion of photoconductor belt 12 acting as a photoreceptor to a predetermined level. It is understood, however, that a separate photoreceptor material can be fixed to photoconductor belt 12 without deviating from the present invention. Scanners 24, 26, 28, 30 selectively discharge an imaging region of photoconductor belt 12 with laser beams 46, 48, 50, 52, respectively, to form latent electrostatic images. Each latent image is representative of one of a plurality of color separation images.

As shown in Figure 1, each development station 32, 34, 36, 38 is disposed directly after one of scanners 24, 26, 28, 30, relative to the direction 45 of movement of photoconductor belt 12, and immediately adjacent corresponding pairs of back-up rolls 32A, 34A, 36A, 38A and squeegee rolls 32B, 34B, 36B, 38B. Each of development stations 32, 34, 36, 38 applies a developer having a color appropriate for the color separation image represented by the particular latent image formed by the corresponding scanner 24, 26, 28, 30. In the system shown in Figure 1, development stations 32, 34, 36, 38 apply yellow (Y), magenta (M), cyan (C), and black (K) developers, respectively, to photoconductor belt 12. A suitable developer is disclosed, for example, in U.S. Patent No. 5,652,282 to Baker et al., entitled "Liquid Inks Using a Gel Organosol."

As photoconductor belt 12 continues to move in direction 45, the next scanner 26, 28, or 30 begins to form a latent image in the imaging region in registration with the latent image formed by the preceding scanner 24, 26, or 28 and developed by the preceding development station 32, 34, or 36. Thus, the color separation images are formed in registration on top of one another in the same imaging region. Scanners 24, 26, 28, 30 and development station 32, 34, 36, 38 may be spaced such that an entire latent image is formed and developed prior to formation and development of the next latent image. For increased speed and reduced size, however, each scanner 26, 28, 30 and development station 34, 36, 38 preferably begins formation and development of the next latent image prior to complete formation and development of the preceding latent image.

After scanners 24, 26, 28, 30 and development stations 32, 34, 36, 38 have formed and developed the latent images, the imaging region of the moving photoconductor belt 12 encounters drying station 40. Drying station 40 may include heated roller 54 that applies heat to photoconductor belt 12 to dry the developer applied by development stations 32, 34, 36, 38. The imaging region of photoconductor belt 12 next encounters transfer station 42. Transfer station 42 includes intermediate transfer roller 56 that forms a nip with photoconductor belt 12 over belt roller 14. Transfer station 42 also includes roller 58 that forms a nip with intermediate transfer roller 56. The developer developed on photoconductor belt 12 at development stations 32, 34, 36, 38 transfers from the photoconductor belt surface to intermediate transfer roller 56 by selective adhesion. Roller 58 serves to transfer the image on intermediate transfer roller 56 to output substrate 60 by application of pressure and/or heat to the output substrate, as is known in the art. Output substrate 50 may comprise, for example, paper, plastic or film.

As shown in Figure 1, free span 54 represents the space or span (conventionally unsupported) between two adjacent rollers. For example, with respect to electrophotographic imaging system 10, there are several free spans, such as those between rollers 14 and 15 (54A), rollers 15 and 16 (54B), rollers 16 and 17 (54C), roller 17 and roller pair 32A, 32B (54D), roller pair 32A, 32B and roller pair 34A, 34B (54E), roller pair 34A, 34B and roller pair 36A, 36B (54F), roller pair 36A, 36B and roller pair 38A, 38B (54G), roller pair 38A, 38B and 18 (54H) and rollers 18 and 14 (541). In each of the free spans 54, photoconductor belt 12 is conventionally not supported. Therefore, in free spans 54, a phenomenon called "troughing" may occur. Troughing refers to the undesirable act of wrinkling, sagging, bending, twisting, rippling or torquing of photoconductor belt 12 in unsupported sections. This phenomenon is also known as "out of plane bending". As is understood by those in the art, troughing of photoconductor belt 12 in a laser strike or developer region in which scanners 24, 26, 28, 30 and development stations 32, 34, 36, 38 are located, degrades the overall quality of a latent image since portions of the latent image are transferred to photoconductor belt 12 or developed on photoconductor belt 12 at various undesired angle and curves. As a result, image plane to plane misregistration or image deformation of a single image plane may occur. Further, belt troughing may contribute to image deformation, and edge detect location errors.

Another issue with past electrophotographic imaging systems is the concept of "belt walking". Belt walking of a photoconductor belt is the movement of the photoconductor belt in a direction substantially perpendicular to the direction of movement 45. With respect to Figure 1 , belt walking refers to the movement of photoconductor belt 12 in a direction into and out of the plane of Figure 1. As a photoconductor belt travels around a series of rollers, the photoconductor belt has a tendency to move into and out of the plane of the figure. The imaging region in which the latent images are formed is commonly fixed to the edge of the photoconductor belt. However, the scanner being used to form each latent image in the imaging region is fixed relative to a start-of-scan coordinate. The side-to-side movement of the photoconductor belt can cause movement of the image region relative to the start-of-scan coordinate thereby degrading the overall quality of the final image since portions of the latent images are transferred to the photoconductor belt at incorrect locations.

Electrophotographic imaging system 10 includes shoes 56 (indicated as 56A, 56B, 56C, 56D) located in free span 54D between rollers 17, 18. Shoes 56A, 56B, 56C, 56D correspond to scanners 24, 26, 28, 30 and development stations 32, 34, 36, 38, respectively. While four shoes are shown in Figure 1, it is understood that any number of shoes may be employed without deviating from the present invention. Shoes 56A, 56B, 56C, 56D are stationary shoes (relative to scanners 24, 26, 28, 30) which provided physical support to photoconductor belt 12, thereby reducing belt positioning and troughing displacement errors. Shoes 56A, 56B, 56C, 56D are stationarily positioned adjacent photoconductor belt 12 such that photoconductor belt 12 comes in contact with a first major surface of each shoe during both the scanning process and the developing process. A slight curvature of shoes 56A, 56B, 56C, 56D provide support and impart stiffness to photoconductor belt 12 during the critical scanning and developing process such that photoconductor belt 12 is incapable of twisting, bending, or troughing.

Also, as shown in Figures 2-4 shoes 56A, 56B, 56C, 56D enable precise belt registration information, for reduction and correction of side-to-side movement of photoconductor belt 12 during the critical scanning and developing process. In particular, belt edge position detectors (i.e., photodetectors) located at each shoe 56A, 56B, 56C, 56D provide a belt edge position signal 52A, 52B, 52C, 52D to controller 53 representative of the position of belt 12. Alternatively, only one photodetector is used and a single belt edge position signal 52A is provided at shoe 56A. Controller 53 provides a corresponding output signal to belt steering system 44. Belt steering system 44 is responsive to the belt position signal for controlling belt steering mechanism 57 to adjust photoconductor belt 12 in direction substantially perpendicular to the direction of movement of the belt 45 along the transport path.

Figure 2 is a perspective, exploded view of one exemplary embodiment of shoe 56 of the present invention. Shoe 56 represents any of shoes 56A, 56B, 56C, 56D shown in Figure 1. Shoe 56 is positioned adjacent photoconductor belt 12, wherein the photoconductor belt 12 includes a first major surface 58 (an imaging surface not viewable) and a second major surface 59. Shoe 56 includes a first major surface 60 which comes in contact with photoconductor belt 12. Shoe 56 also includes second major surface 61, shafts 62A, 62B, shaft receptacles 64A, 64B, photoconductor belt edge detect sensor or photodetector 66, electrically isolating spacer 68, circuit board 70, fasteners 72A, 72B, 72C, and aperture 74. Shafts 62A, 62B secure (i.e., mechanically couple) shoe 56 to other portions of electrophotographic imaging system 10, not shown for clarity purposes. Shafts 62 A, 62B also ensure that shoe 56 is properly located adjacent both a scanner and a development station region (i.e., a laser strike region and a developer region). Shoe 56 extends longitudinally across the belt second major surface 59 in a direction substantially perpendicular to the direction of movement 45 of the belt 12. Further, major surface 58 includes a laser strike region positioned along the scan line (indicated by dashed line 75) of the laser scanner associated with shoe 56. The location of shoe 56 in connection with a scanner and development station will be described in further detail with reference to Figures 3 and 4. Aperture 74 is a hole or opening which traverses shoe 56 from first major surface 60 to second major surface 61. Photoconductor belt edge detect sensor 66 is located within aperture 74 adjacent first major surface 60. Sensor 66 is positioned immediately adjacent photoconductor belt 12, allowing for belt edge position detection with less chance of error. Spacer 68 is located on top of photoconductor belt edge detect sensor 66 within aperture 74. Finally, circuit board 70 is positioned on top of electrically isolating spacer 68 and secured to second major surface 61 of shoe 56 via fasteners 72A, 72B, 72C. Fasteners 72A, 72B, 72C can be any type of suitable fastener, including a bolt or a screw. During an electrophotographic imaging process, a laser beam from a scanner assembly, such as scanners 24, 26, 28, 30 (scanner 24 is shown), scans photoconductor belt 12 in a laser strike region along laser scan line 75. The scanner 24 is positioned within electrophotographic imaging system 10 such that it is substantially centered between first edge 76 and second edge 77. Electrophotographic imaging system 10 is designed such that the laser travels across photoconductor belt 12 substantially perpendicular to the direction of movement 45 of photoconductor belt 12. The scanner 24 scans laser beam 46 representative of the image data across the first major surface 58 of photoconductor belt 12 within the laser strike region to produce the latent image. In one preferred embodiment, the laser beam's range of motion travels past first edge 76 of photoconductor belt 12 such that it comes in contact with and is incident on photoconductor belt edge detect sensor 66. Once photoconductor belt edge detect sensor 66 has been contacted by laser beam 46, photoconductor belt edge detect sensor 66 provides an output signal to circuit board 70, representative of the position of the edge of photoconductor belt 12. In one aspect at scanner 24, laser beam 46 contacts sensor 66 first, then encounters belt edge 76. The belt edge 76 position signal is measured relative to the portion of the sensor 66 to the end of aperture 74, not covered by the belt 12. This information is then electrically transmitted (via the output signal) to controller 53 and belt steering system 44 (shown in Figure 1). Based upon the information received from photoconductor belt edge sensor 66, belt steering system 44 is capable of altering the movement of photoconductor belt 12 in a direction substantially peφendicular to direction of movement 45 (as shown by arrow A), to perform belt steering and/or image registration.

Photoconductor belt 12 can undergo side-to-side movement during an electrical photographic imaging process. The imaging region of photoconductor belt 12 in which the latent images are formed is affixed to a part of photoconductor belt 12. However, scanners 24, 26, 28, 30 and development stations 32, 34, 36, 38 are affixed relative to a start-of-scan coordinate. The side- to-side movement of photoconductor belt 12, known as belt walking, causes movement of the imaging regions relative to the start-of-scan coordinate. As a result, misregistration may occur between different scan lines and different latent images. This misregistration may significantly degrade image quality. Photoconductor belt edge detect sensor 66, in coordination with belt steering system 44, minimizes belt walking and thereby ensures proper registration of latent images. Further, "apparent" belt walking exists due to sagging, wrinkling, and due to among other reasons out of round or misaligned rollers (e.g., squeegee rollers or squeegee back-up rollers). Shoe 56 corrects "apparent" belt walking in the laser striker region 82. As belt 12 moves across the curved surface of shoe 56, belt troughing is prevented, thereby allowing for true belt edge position detection and precise image registration. One suitable belt position or belt edge detection system for use with the imaging system is accordance with the present invention is disclosed in U.S. Patent No. 5,978,003 to Brenner, Jr., entitled "Belt Position Detection System for Belt Registration in an Electrophotographic Imaging System", the entire contents of which is incoφorated herein by reference.

Figure 3 is a side view illustrating one exemplary embodiment of shoe 56 positioned within an exposure region or a laser strike region 82 and developer region 84, in accordance with the present invention. As shown in Figure 3, shoe 56 includes first curved surface 78 and second curved surface 80. Photoconductor belt edge detect sensor 66 is located immediately adjacent first major surface 58 of shoe 56. First curved surface 78 is in operational alignment with laser strike region 82 (i.e., scanning region) of scanner 24, and second curved surface 80 is in operational alignment with developing region 84 of developer 32.

In one aspect, first curved surface 78 can be viewed as an arc having a center axis 86 extending longitudinally across photoconductor belt 12. The photoconductor belt 12 is arced in a similar manner. A laser region belt wrap angle is defined by the portion of the arced belt 12 which contacts first curved surface 78. In one preferred embodiment, the laser region belt wrap angle is 2°. Second curved surface 80 can be viewed as an arc having a center axis 88 extending longitudinally across photoconductor belt 12. A developer region belt wrap angle is defined by the portion of the arced belt 12 which contacts second curved surface 80. In one preferred embodiment, the developer region belt wrap angle is 2.5°. Preferably, second center axis 88 is coaxial with shaft 62A (as shown). As such, movement of shoe 56 in the X - Y direction (i.e., via rotation about coaxial center axis 88 at shaft 62 A) does not affect the positioning or support of photoconductor belt 12. Laser strike region 82 and developer region 84 must be physically separated which also determines locations of first center axis 86 and second center axis 88.

During an electrophotographic imaging process, photoconductor belt 12 is located adjacent to and comes in contact with first curved surface 78 and second curved surface 80. As belt 12 moves along first curved surface 78, it takes on the shape of first curved surface 78. As such, shoe 56 supports belt 12 and imparts a curved shape to belt 12, increasing its structural integrity. Scanner 24, which can represent any of scanners 24, 26, 28, 30, provides laser beam 46 which strikes photoconductor belt 12 while photoconductor belt 12 is in contact with first curved surface 78 adjacent photoconductor belt edge detect sensor 66 along scan line 75 (shown in Figure 1) and within laser strike region 82. Alternatively, the block representation of scanner 24 may be part of an alternative image exposure system for exposing image data, such as a high resolution light emitting diode (LED) assembly. Shoe 56 prevents out-of-plane bending or troughing of photoconductor belt 12 during the scanning of image data since the belt 12 assumes the shape of first curved surface 78. Therefore, shoe 56 ensures a proper image strike which will produce desired latent images. In addition, the curved surface of first curved surface 78 provides an even broader surface for which laser beam 84 may strike photoconductor belt 12. This further ensures the registration of a proper latent image.

Similarly, shoe 56 provides support to photoconductor belt 12 in developer region 84 where development station 32, which represents any one of development stations 32, 34, 36, 38, develops the latent images. Second curved surface 80 also provides a broader area for the development of the latent images. Since second center axis 88 and shaft 62 A are coaxial, first and second curved surfaces 78, 80 also ensure that photoconductor belt 12 contacts shoe 56 in both the laser strike region 82 and developer region 84. A flat surface not properly positioned would not ensure proper scanning or developing. More specifically, first and second curved surfaces 78 and 80 minimize the critical issue of orientation of a support mechanism with respect to a photoconductor belt. In other words, the orientation of a support mechanism in the x and y directions is no longer critical (due to the coaxial center axis). In conventional electrophotographic imaging systems which utilize a flat support mechanism in either the laser strike or developer regions, the orientation of the flat support mechanism is critical. If the flat support mechanism was not properly orientated in the x and y directions, the flat support mechanism would not provide the proper support (i.e., belt positioning) in both the laser strike region 82 and the developer region 84 for which it was designed. However, with the coaxial design of the present invention, first and second curved surfaces 78, 80 provide proper support and positioning to photoconductor belt 12, and minimizing out-of-plane bending or troughing.

In one preferred embodiment, first major surface 60 (including first curved surface 78 and second curved surface 80) is at least partially reflective within laser strike region 82. The reflective surface, in combination with first curved surface 78, deflects laser beam 84 such that laser beam 84 does not reflect off of the reflective surface of photoconductor belt edge detect sensor 66 back into scanner 82.

In one preferred embodiment, first curved surface 78 and second curved surface 80 are convex surfaces with respect to photoconductor belt 12. Also, a radius RI of first curved surface 78 is larger than the radius R2 of second curved surface 80. Radius RI is minimized to provide maximum stiffness to belt 12, yet maximized since a larger radius provides a larger area to laser strike region 82 and reduces any affects aperture 74 may have on belt 12. The larger radius in the laser strike region facilitates easier laser alignment, along with a minimized edge detect slot width minimizes belt displacement in edge detect aperture. In one preferred embodiment, first curved surface 78 has a radius RI in the range of 5-20 times greater than the radius R2 of second curved surface 80. More specifically, in one preferred embodiment, first curved surface 78 has a radius RI of 190.50 inches (483.87 cm), while the radius R2 of the second curved surface 80 is 15.50 inches (39.37 cm). Figure 4 is a partial, sectional view of shoe 56 as seen from line 4-4 of

Figure 3. As previously discussed, scanner 24 is stationarily positioned substantially in the center of photoconductor belt 12 (i.e., centered on the imaging region). Thus, laser beam 46 is not directed peφendicular to photoconductor belt 12 once laser beam 46 reaches first edge 76 or second edge 77 of photoconductor belt 12. Rather, laser beam 46 is directed at an angle to photoconductor belt 12 at edges 76, 77. In one embodiment, this angle is in the range of 10°-80°, and in one preferred aspect, is between 15° and 30°. In one exemplary embodiment shown, the laser beam is transmitted towards photoconductor belt 12 and shoe 56 at an angle of approximately 20°. It is undesirable to have laser beam 46 reflected off of edge 100 back into the photoconductor belt edge detect sensor (photodetector) 66 and/or scanner 24.

Aperture 74 includes a ramp or angled edge 100. Ramp 100 operates to reflect laser beam 46 away from belt edge detect sensor 66 and scanner 24, thereby eliminating the need for masking of belt edge detect sensor 66 or the use of a light redirecting prism. Ramp 100 includes a reflecting surface or at least partially reflecting surface which is angled relative to a plane defined by a major surface 66A of belt edge detect sensor 66 (indicated by angle θ). In one aspect, angle θ is about 20°. Alternatively, edge 100 may comprise a substantially light absorbing surface. Ramp 100 may reflect laser beam 46 to a light absorbing surface. Ramp 100 allows for a true belt edge detection signal 52A to be sent to controller 53.

Claims

WHAT IS CLAIMED IS:

1. An electrophotographic imaging system (10) for producing a latent image from image data, the system comprising: a photoconductor belt (12) capable of movement in a first direction (45) forming a continuous transport path, the photoconductor belt having a first major surface (58) and a second major surface (59); a scanner assembly (24, 26, 28, 30) including a scanner for scanning a laser beam representative of the image data across the first major surface within a laser strike region (82) to produce the latent image; and a shoe (56) extending across the second major surface, including a first curved surface (78) within the laser strike region such that the second major surface contacts the first curved surface while the scanner scans the laser beam across the first major surface.

2. An electrophotographic imaging system (10) for producing a latent image from image data, the system comprising: a photoconductor belt (12) capable of movement in a first direction (45) forming a continuous transport path, the photoconductor belt having a first major surface (58) and a second major surface (59); an image exposure system (24, 26, 28, 30) having a light source for exposing the photoconductor belt representative of the image data across the first major surface within an exposure region (82) to produce the latent image; and a shoe (56) extending across the second major surface, including a first curved surface (78) within the exposure region such that the second major surface moves across a portion of the first curved surface and the photoconductor belt takes the shape of the first curved surface within the exposure region while the exposure system exposes the image data across the first major surface.

3. The article of claim 1, further comprising: a developer (32, 34, 36, 38) for developing the latent image on the photoconductor belt within a developing region (84), wherein the developing region is adjacent the laser strike region; and a second curved surface (80) extending longitudinally across the second major surface, wherein the second major surface contacts the second curved surface within the developing region during developing of the latent image on the photoconductor belt.

4. The article of claim 3, wherein the shoe (56) includes the second curved surface.

5. The article of claim 1 or 2, wherein the first curved surface (78) is a convex curved surface, having a first center axis (62A) extending longitudinally across the second major surface substantially parallel to the shoe.

6. The article of claim 3, wherein the second curved surface is a convex curved surface, having a second center axis (88) extending longitudinally across the second major surface substantially parallel to the shoe.

7. The article of claim 6, wherein the second center axis is coaxial with the first center axis.

8. The article of claim 4, wherein the first curved surface has a radius greater than a radius of the second curved surface.

9. The article of claim 1 or 2, further comprising a belt position detection system including a photodetector (66) coupled to the shoe and extending across an edge of the photoconductor belt, wherein the photodetector is responsive to a light source for providing a belt edge position detection signal representative of belt position.

10. The article of claim 9, wherein the shoe (56) includes an aperture (74) in the first curved surface in the laser strike region, the aperture extending at least partially through the shoe, and wherein the edge of the photoconductor belt extends partially across the aperture.