Photoreceptor belt control apparatus for printer

Abstract: A photoreceptor belt control apparatus for a printer designed to correct lateral traveling of a photoreceptor belt traveling by being supported by rollers rotatably installed on a belt frame (100), and/or to control tension for the photoreceptor belt. The apparatus includes an auxiliary frame comprising a pair of auxiliary frame members (51, 55) slidably and pivotally installed on the belt frame (100), a steering roller (61) whose ends are rotatably installed respectively on the auxiliary frame, the steering roller (61) rotating in contact with the photoreceptor belt, a shaft (65) whose ends are rotatably installed on the belt frame (100), a cam unit (70) installed on at least one end of the shaft (65) for controlling the inclination of the steering roller (61) by pivoting each of the auxiliary frame members (51, 55) according to the rotation position of the shaft (65), and a tension control unit (80) for controlling tension to be applied to the photoreceptor belt by sliding the pair of auxiliary frame members (51, 55).

Description: The present invention relates to a photoreceptor belt control apparatus for a printer which steers a photoreceptor belt and applies tension to and removes tension from the photoreceptor belt, and more particularly, to a photoreceptor belt control apparatus for a printer for preventing the photoreceptor belt from traveling laterally and applying tension to and releasing tension from the photoreceptor belt by driving auxiliary frames for supporting a steering roller while depressing both ends of the steering roller. A general printer such as a laser printer forms a latent electrostatic image by scanning a photoreceptor belt using a laser scanning unit, develops the latent electrostatic image with a color ink using a developing unit, and transfers the developed image onto a printing paper. Referring to Figure 1, a general printer includes a photoreceptor belt 10 which rotates continuously along a fixed path around rollers 12, 14 and 21 installed in the main body of the printer. The general printer further includes an erase lamp 15 for erasing a surface potential formed on the photoreceptor belt 10, a charger 17 for charging the photoreceptor belt 10 with a predetermined potential, a plurality of laser scanning units (LSU) 18 for scanning the photoreceptor belt 10 with laser beams to form a latent electrostatic image for each color, and a plurality of developing units 19 for developing portions on which the latent electrostatic images have been formed. In the printer having such a configuration, the photoreceptor belt 10 travels around the rollers 12, 14 and 21, and thus travels laterally in the length direction of the rollers 12, 14, and 21. Also, the photoreceptor belt 10 must be released from tension upon replacement of the photoreceptor belt 10 or upon attachment and detachment of a belt unit including the photoreceptor belt 10 and the rollers 12, 14, and 21. Referring to Figures 1 and 2, a conventional photoreceptor belt control apparatus for the general printer is comprised of a photoreceptor belt steering unit 20 for correcting the lateral traveling of a photoreceptor belt on the basis of information detected by a lateral traveling detector (not shown), and a tension applying/releasing unit 40 for controlling the tension applied to the photoreceptor belt. The photoreceptor belt steering unit 20 includes a frame 23 installed on a printer main body 1, a pivot member 25 pivotally installed on the frame 23, a steering roller 21 installed on the pivot member 25 for supporting the photoreceptor belt 10 so that the photoreceptor belt 10 rotates along a fixed path, a pair of stable rollers 27 installed on the frame 23 to prevent the photoreceptor belt 10 passing the steering roller 21 from being crumpled, and a control unit 30 installed on the printer main body 1 for controlling the upward and downward (direction indicated by arrow A) tilt of the steering roller 21. The tension applying/releasing unit 40 is comprised of a guide bar 41 having one end on which the center of the pivot member 25 is hinged, a first cam member 43, an elastic member 45 installed on the outer circumference of the guide bar 41, the elastic member 45 having the ends thereof respectively contacting the first cam member 43 and the frame 23, and a control knob 47 for controlling the first cam member 43. The control knob 47 controls the elasticity of the elastic member 45 to adjust the application/release of tension to/from the steering roller 21. The pivot member 25 is coupled to the guide bar 41 elastically combined with the frame 23 by a coupling pin 39, and pivots on a X-Y plane on the basis of a portion where the coupling pin 39 is coupled. The pivot member 25 pivots in a direction to compensate for an unbalanced pressure applied to the contact portion between the steering roller 21 and the photoreceptor belt 10 by the elastic member 45 wound on the guide bar 41. A sliding plate 46 is slidably installed on the outer circumference of the guide bar 41 so as to press the elastic member 45 down according to the rotation position of the first cam member 43. A shaft 21a of the steering roller 21 is coupled to a holding hole 25a formed in the pivot member 25. An elastic piece 26 for pressing the shaft 21a of the steering roller 21 down is installed on the holding hole 25a. The control unit 30 includes a driving motor 31 fixed to the printer main body 1, a second cam member 33 whose center is combined with a shaft 31a of the driving motor 31, the second cam member 33 having a cam hole 33a, and a rotating guide protrusion 35 coupled to the pivot member 25 and installed so as to fit into the cam hole 33a. The position of the cam hole 33a varies with the rotation of the driving motor 31, thereby changing the height of the rotating guide protrusion 35. The steering roller 21 pivots on the guide bar 41 in the direction indicated by arrow A. When a lateral traveling degree of the photoreceptor belt 10 is detected by the lateral traveling detector, the steering roller 21 tilts according to the position of the second cam member 33. Thus, the photoreceptor belt 10 is moved in any one width direction, and the lateral traveling thereof is thus corrected. The pair of stable rollers 27 are installed parallel to the steering roller 21 on the frame 23, and contact respectively a portion of the photoreceptor belt 10 heading for the steering roller 21 and a portion of the photoreceptor belt 10 passed through the steering roller 21 to prevent the photoreceptor belt 10 from crumpling. As described above, the conventional photoreceptor belt control apparatus having such a configuration has a structure in which the steering roller 21 can pivot about its center, thus requiring internal space in a printer main body on which a pivot member, a guide bar and a frame are to be installed. Thus, there is a limit in minimizing the entire size of the photoreceptor belt control apparatus. Also, since elasticity applied to the guide bar is adjusted by pivoting the first cam member, only a structure of applying tension to a photoreceptor belt or releasing the applied tension has been disclosed, However, a configuration for moving the steering roller back in the direction indicated by arrow X is not disclosed. With a view to solve or reduce the above problems, it is an aim of embodiments of the present invention to provide a photoreceptor belt control apparatus for a printer designed to apply/release tension by driving auxiliary frames installed on both ends of a steering roller for guiding the tilt of the steering roller and supporting the steering roller while depressing both ends of the steering roller. US 5,659,851 describes a prior art type apparatus and method for steering an endless belt toward a lateral target belt position while the endless belt is transported by a transporting mechanism. A steering roller contacts the belt inner surface, the steering roller being rotatable about a roller axis and being pivotable about a steering axis, and the steering roller having a first roller end. A carriage supports the steering roller and is pivotable about a steering axis such that the steering roller is pivotable about the steering axis. A first member is positioned adjacent to the first roller end and functionally connected to the-carriage. The first member contacts the belt inner surface when the first belt edge extends sufficiently beyond the first roller end. The first member applies greater friction to the endless belt than the steering roller when the belt contacts the first member. The first member is positioned relative to the steering axis such that contact between the first member and the belt causes the first member to apply a first torque to the carriage means about the steering axis. US 5,078,263 describes a web steering mechanism. Small tilting mechanisms of the idler roll assembly, under the control of a servo-motor are effective to alter the angle at which the web enters and/or leaves the roll, to cause the web to walk along the tilted roll. US 3,500,694 describes a belt tracking arrangement for use with a belt supporting roller wherein the shaft for the roller is mounted for short pivotable movement about an axis normal to its axis and which lies in a plane that bisects the angle of the belt runs on either side of the roller. According to a first aspect of the invention, there is provided a photoreceptor belt control apparatus for a printer designed to correct lateral traveling of a photoreceptor belt traveling by being supported by rollers rotatably installed on a belt frame, and to control tension for the photoreceptor belt, the apparatus comprising: an auxiliary frame comprising a pair of auxiliary frame members slidably and pivotally installed on the belt frame; a steering roller whose ends are rotatably installed respectively on the auxiliary frame, the steering roller rotating in contact with the photoreceptor belt; a shaft whose ends are rotatably installed on the belt frame; a cam unit installed on at least one end of the shaft for controlling the inclination of the steering roller by pivoting each of the auxiliary frames according to the rotation position of the shaft; and a tension control unit for controlling tension to be applied to the photoreceptor belt by sliding the pair of auxiliary frame members, whereby the tension control unit comprises: an elastic biasing means for elastically biasing the auxiliary frame against the belt frame; and a driving means for selectively regulating an elasticity to be applied to the auxiliary frame members by the elastic biasing means, the driving means comprising a driving source for providing a driving force, a driving plate rotatably installed on a fixing plate installed between parts of the belt frame, and a pair of lever members pivotally hinge-combined with the fixing plate, each lever member being provided with one end coupled to the driving plate and with its other end designed to selectively depress respective ones of the pair of auxiliary frame members according to the position of the driving plate in the direction in which tension applied to the photoreceptor belt is released, wherein tension applied to the photoreceptor belt can be released according to the position of the driving plate. Preferably, the cam unit comprises: a cam member installed on at least one end of the shaft so that the rotation center can be eccentric from the center of the shaft; and an elevating guide hole formed on at least one auxiliary frame member so that the cam member can fit into the elevating guide hole, the elevating guide hole having upper and lower surfaces contacting the outer circumference of the cam member wherein the auxiliary frame pivots according to the rotation of the cam member to control the inclination of the shaft. Preferably, the rotation of the shaft is controlled by an external driving source installed in a printer main body, and a coupler is further installed on at least one end of the shaft so as to mesh with the external driving source. The auxiliary frame may further comprise a guide bracket protruding to one side so as to contact the end of the lever member. The elastic biasing means may comprise: a coupling protrusion extending from the auxiliary frame; and an elastic member provided with one end coupled to the coupling protrusion and the other end coupled to the end of the lever member to elastically bias the auxiliary frame against the belt frame. The elastic biasing means may comprise: an elastic member for elastically biasing the auxiliary frame against the belt frame; a first coupling protrusion extending from the belt frame, to which one end of the elastic member is coupled; and a second coupling protrusion extending from the auxiliary frame, to which the other end of the elastic member is coupled. The first coupling protrusion may protrude from the belt frame through a guide slot formed in the auxiliary frame and becomes the pivoting center of the auxiliary frame. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 is a schematic view illustrating a printer adopting a conventional photoreceptor belt control apparatus; Figure 2 is a schematic exploded perspective view illustrating a conventional photoreceptor belt control apparatus; Figure 3 is a perspective view illustrating a photoreceptor belt control apparatus for a printer according to an embodiment of the present invention; Figure 4 is a cross-sectional view taken along line IV-IV of Figure 3; Figure 5 is a partially extracted view illustrating a photoreceptor belt control apparatus for a printer according to another embodiment of the present invention; Figures 6 through 8 are schematic views illustrating the steering operation of a photoreceptor belt when the photoreceptor belt travels normally; Figures 9 through 11 are schematic views illustrating the steering operation of a photoreceptor belt in the direction indicated by arrow -B when the photoreceptor belt travels laterally with respect to the direction indicated by arrow B; Figure 12 is a schematic plan view showing the case in which tension is applied to a photoreceptor belt for a photoreceptor belt tension control apparatus according to the present invention; and Figure 13 is a schematic plan view showing the case in which tension is released from a photoreceptor belt for a photoreceptor belt tension control apparatus. Figure 3 is a schematic exploded perspective view illustrating a photoreceptor belt control apparatus for a printer according to an embodiment of the present invention, and Figure 4 is a cross-sectional view taken along line IV-IV of Figure 3. Referring to Figures 3 and 4, the photoreceptor belt control apparatus for a printer is comprised of an auxiliary frame comprising a pair of first and second auxiliary frame members 51 and 55, a steering roller 61 pivotally installed on the end of each of the first and second auxiliary frame members 51 and 55, a shaft 65 having the ends thereof pivotally installed on a belt frame 100, a cam unit 70 installed on at least one end of the shaft 65 for adjusting the inclination of the steering roller 61 according to the rotation position of the shaft 65 by pivoting the first and/or second auxiliary frame members 51 and/or 55, and a tension control unit 80 for controlling tension applied to the photoreceptor belt by sliding the first and second auxiliary frame members 51 and 55. The first and second auxiliary frame members 51 and 55 are slidably installed with respect to the belt frame 100 in the direction in which tension to be applied to the photoreceptor belt 10 increases and/or decreases. First and second elevating guide holes 52 and 56, a component element of the cam unit 70, are formed on the first and/or second auxiliary frame members 51 and 55. First and second guide holes 53 and 57 (see Figure 7) for guiding the sliding of the first and second auxiliary frame members 51 and 55 with respect to the belt frame 100 are also formed on the first and/or second auxiliary frame members 51 and/or 55. Both ends of the steering roller 61 are rotatably installed on the ends of the first and second auxiliary frame members 51 and 55. Here, a bearing 63 is installed between the steering roller 61 and each of the first and second auxiliary frame members 51 and 55. The steering roller 61 contacts the photoreceptor belt 10 and is rotated by the traveling. of the photoreceptor belt 10. Both ends of the steering roller 61 are lifted by the cam unit 70 in opposite directions, such that the steering roller 61 corrects the lateral traveling of the photoreceptor belt 10. The shaft 65 has both ends rotatably installed on the belt frame 100, and the cam unit 70 is installed on at least one end of the shaft 65. The rotating direction of the shaft 65 is controlled by an external driving source installed on a printer main body (not shown). Here, it is preferable that a coupler 68 is further installed on at least one end of the shaft 65 to transmit a rotation force from the external driving source to the shaft 65. The addition of the coupler 68 facilitates separation and coupling of the belt frame 100 from and to the printer main body. The cam unit 70 is installed on at least one end of the shaft 65 and controls the inclination of the steering roller 61 by pivoting the first and/or second auxiliary frame members 51 and/or 55 according to the rotating position of the shaft 65. Figure 4 shows an example of the cam unit 70 installed on both ends of the shaft 65. Referring to Figure 4, the cam unit 70 includes first and second cam members 71 and 75 and first and second elevating guide holes 52 and 56 formed respectively on the first and second auxiliary frame members 51 and 55. The first and second cam members 71 and 75 are installed on both ends of the shaft 65 at the first and second auxiliary frame members 51 and 55 to be eccentric from the center of the shaft 65. The first and second elevating guide holes 52 and 56 are slots formed respectively on the first and second auxiliary frame members 51 and 55 to insert the first and second cam members 71 and 75 thereinto. The first and second elevating guide holes 52 and 56 are formed to a predetermined height in a direction indicated by arrow Z so that the upper and lower surfaces of each of the first and second elevating guide holes 52 and 56 can contact the outer circumference of each of the first and second cam members 71 and 75, and are formed in the sliding direction (X direction) of the first and second auxiliary frame members 51 and 55. Thus, the first and second auxiliary frames 51 and 55 are pivoted on a plane X-Z on the basis of a coupling protrusion 101 of the belt frame 100 according to whether the long radius end and the short radius end of the first and second cam members 71 and 75 contact the upper surfaces or lower surfaces of the first and second elevating guide holes 52 and 56. Here, it is preferable that the first cam member 71 has the same size and shape as those of the second cam member 75, and the first elevating guide hole 52 has the same size and shape as those of the second elevating guide hole 56. Also, preferably, the long radius and short radius of the first cam members 71 are positioned opposite to those of the second cam member 75. Accordingly, when one auxiliary frame part, e.g., the first auxiliary frame member 51, is pivoted by the cam unit 70 clockwise on the basis of the coupling protrusion 101 on the X-Z plane, the other auxiliary frame part, e.g., the second auxiliary frame member 55, is rotated by the cam unit 70 counterclockwise on the basis of the coupling protrusion 101 on the X-Z plane. Therefore, both ends of the steering roller 61 axially pivot on a plane Y-Z. Referring to Figure 3, the tension control unit 80 is comprised of an elastic biasing means 81 for elastically biasing the first and second auxiliary frame members 51 and 55 with respect to the belt frame 100, and a driving means 90 designed to selectively regulate an elasticity to be applied to the first and second auxiliary frame members 51 and 55 by the elastic biasing means 81. The driving means 90 includes a driving source 91 for providing a driving force, a driving plate 93 which rotates by receiving the driving force from the driving source 91, and first and second lever members 95 and 97 designed to press down on the first and second auxiliary frame members 51 and 56. The driving source 91 and the driving plate 93 are installed on a fixing plate 105 installed between the pair of belt frames 100. The driving plate 93 is rotatably installed on the fixing plate 105, and rotates by receiving power from the driving source 91. The first and second lever members 95 and 97 are pivotally hinge-combined with the fixing plate 105, whose one end of each is combined with the driving plate 93 so as to pivot in engagement with the rotation of the driving plate 93. Here, a driving protrusion 93a is installed on the driving plate 93 at a position eccentric from the rotation center of the driving plate 93, and slots 95a and 97a to be combined with the driving protrusion 93a are formed respectively in the first and second lever members 95 and 97. Thus, when the driving plate 93 is rotated, the first and second lever members 95 and 97 pivot on hinges 106 and 107 combined with the fixing plate 105, according to the position of the driving protrusion 93a. The respective ends of the first and second lever members 95 and 97 selectively contact the first and second auxiliary frame members 51 and 55 to release tension from the first and second auxiliary frame members 51 and 55. That is, when tension is released from the photoreceptor belt 10 to replace the photoreceptor belt 10, the first and second lever members 95 and 97 contact respectively the first and second auxiliary frame members 51 and 55 and moves the first and second auxiliary frame members 51 and 55 in the -X direction. In a normal case such as a printing mode, the first and second lever members 95 and 97 do not contact the first and second auxiliary frame members 51 and 55, and the first and second auxiliary frame members 51 and 55 are elastically biased in the X direction by the elastic biasing means 81. It is preferable that first and second guide brackets 51a and 55a are further formed on the first and second auxiliary frame members 51 and 55 so that the respective ends of the first and second lever members 95 and 97 can contact the first and second guide brackets 51a and 55a. As shown in Figure 3, the elastic biasing means 81 according to an embodiment is interposed between each of the first and second lever members 95 and 97 and each of the first and second auxiliary frame members 51 and 55, and elastically biases the steering roller 61 in the direction in which the tension of the photoreceptor belt 10 increases. For this, the elastic biasing means 81 is comprised of first and second elastic members 83 and 85 (see Figure 8) for elastically biasing the first and second auxiliary frame members 51 and 55 against the belt frame 100, and a pair of coupling protrusions 51b and 55b (see Figure 8) formed respectively on the first and second auxiliary frame members 51 and 55. The first and second elastic members 83 and 85, typical tension springs, are installed between the pair of coupling protrusions 51b and 55b and the first and second lever members 95 and 97. In this structure, the coupling protrusions 51b and 55b and the first and second lever members 95 and 97 all reverse even when tension is released, so that elasticity applied to the first and second elastic members 83 and 85 does not increase. Therefore, the first and second elastic members 83 and 85 are not deformed. An elastic biasing means 81' according to another embodiment is shown in Figure 5. Installation of the elastic biasing means 81' for the first auxiliary frame 51 will now be described as follows. The elastic biasing means 81' can be configured by including an elastic member 83 for elastically biasing the first auxiliary frame member 51 against the belt frame 100, a first coupling protrusion 85 which protrudes from the belt frame 100 and is combined with one end of the elastic member 83, and a second coupling protrusion 51b which protrudes from the first auxiliary frame member 51 and is combined with the other end of the elastic member 83. The first coupling protrusion 85 protrudes from the belt frame 100 through a guide 53' formed in the first auxiliary frame member 51, and becomes the rotation center of the first auxiliary frame member 51. For example, the shaft 65 is installed between the first and second coupling protrusions 85 and 51b as shown in Figure 5, but it can be installed between the first coupling protrusion 85 and the steering roller 61. Meanwhile, the first and second coupling protrusions 85 and 51b and the elastic member 83 are installed on the second auxiliary frame member in the same manner as on the first auxiliary frame member. Hereinafter, the operation of the photoreceptor belt control apparatus for a printer according to an embodiment of the present invention will be described by dividing it into a steering operation and a tension control operation. The steering operation of the photoreceptor belt control apparatus for a printer according to the present invention will be described referring to Figures. 6 through 11. Figures. 6 through 8 are schematic views illustrating a photoreceptor belt 10 which travels normally. Figure 6 is a front view, Figure 7 is a cross-sectional view taken along line VII-VII of Figure 6, and Figure 8 is a cross-sectional view taken along line VIII-VIII of Figure 6. Here, the long radius end 71a and the short radius end 71b of the first cam member 71 are arranged in the slot direction of the first elevating guide hole 52, and the long radius end 75a and the short radius end 75b of the second cam member 75 are arranged in the slot direction of the second elevating guide hole 56. That is, the centers of the first and second cam members 71 and 75 meet respectively with the centers of the up-and-down widths of the first and second elevating guide holes 52 and 56. Thus, the first and second auxiliary frame members 51 and 55 are parallel to each other, and the steering roller 61 is parallel to the direction indicated by arrow Y. Figures 9 through 11 are schematic views illustrating the photoreceptor belt control apparatus for a printer according to the present invention configured to steer the photoreceptor belt 10 in the direction indicated by arrow - B when the photoreceptor belt 10 travels laterally with respect to the direction indicated by arrow B. Figure 9 is a front view, Figure 10 is a cross-sectional taken along line X-X of Figure 9, and Figure 11 is a cross-sectional taken along line XI-XI of Figure 9. Here, the long radius end 71a and the short radius end 71b of the first cam member 71 respectively contact the upper surface 52a and the lower surface 52b of the first elevating guide hole 52 by the rotation of the shaft 65, and the long radius end 75a and the short radius end 75b of the second cam member 75 respectively contact the lower surface 56b and the upper surface 56a of the second elevating guide hole 56. Accordingly, the first auxiliary frame member 51 is rotated a predetermined angle clockwise on the first coupling protrusion 101 to lift the end of the steering roller 61 in the direction indicated by arrow Z, and the second auxiliary frame member 55 is rotated a predetermined angle counterclockwise on the first coupling protrusion 101 to drop the end of the steering roller 61 in the direction indicated by arrow -Z. Thus, the steering roller 61 is inclined to move the photoreceptor belt 10 in the direction indicated by arrow -B, thereby correcting the lateral traveling of the photoreceptor belt 10. On the other hand, when the photoreceptor belt 10 travels laterally with respect to the direction indicated by arrow -B, the first and second cam members 71 and 75 are arranged in a direction opposite to that described in Figures. 9 through 11 such that the steering roller 61 is inclined to move the photoreceptor belt 10 in the direction indicated by arrow B, thereby correcting the lateral traveling of the photoreceptor belt 10. As shown in Figures 3 and 6 through 11, the present invention describes installation of first and second cam members 71 and 75 as a cam unit 70 respectively on the sides of the first and second auxiliary frame members 51 and 55, but this installation is just an example. A cam member as the cam unit 70 can be installed on either the first or second auxiliary frame member 51 or 55 side, and the basic operating principle of the cam member is the same as that described above. Thus, the cam member will not be described again. The operation of the tension control means 90 in the photoreceptor belt control apparatus for a printer according to embodiments of the present invention will now be described referring to Figures. 12 and 13. Figure 12 shows the case in which tension is applied to a photoreceptor belt for the photoreceptor belt tension control apparatus. Referring to Figure 12, the driving plate 93 is rotated by the driving source 91 to arrange the end of each of the first and second lever members 95 and 97 to be advanced in the direction indicated by arrow X. In this case, the first and second auxiliary frame members 51 and 55 are advanced in the direction indicated by arrow X by the elastic bias of the first and second elastic members 83 and 85, thereby applying tension to the photoreceptor belt 10. Meanwhile, when an external force is applied to the photoreceptor belt 10 in the direction indicated by arrow -X, the steering roller 61 is partially reversed in the direction indicated by arrow -X. Meanwhile, when the external force is released, the steering roller 61 is advanced by the first and second elastic members 83 and 85. Figure 13 shows a case in which tension is released from the photoreceptor belt 10 for a photoreceptor belt tension control apparatus when the belt frame 100 in the printer main body is replaced or the photoreceptor belt 10 is replaced. As shown in Figure 13, the driving plate 93 is rotated by the driving source 91 so that the driving protrusion 93a can be placed between the steering roller 61 and the rotation center of the driving plate 93. Thus, the first and second lever members 95 and 97 rotate on the hinges 106 and 107, and the end of each of the first and second lever members 95 and 97 reverses in the direction indicated by arrow -X. At this time, the first and second lever members 95 and 97 contact the first and second guide brackets 51a and 55a and reverse the first and second auxiliary frame members 51 and 55. Thus, tension is released from the photoreceptor belt 10 while the steering roller 61 reverses. In this case, none of elastic bias forces generated by the first and second elastic members 83 and 85 reach the first and second auxiliary frames 51 and 55. As described above, application and release of tension to and from the photoreceptor belt can be freely controlled by the operation of the driving source 91. The photoreceptor belt control apparatus for a printer configured as described above has the following effects. First, a spring force for depression can be dispersed by adopting a structure of pressing both ends of the steering roller down, making use of small components possible. Thus, a space occupied by the photoreceptor belt control apparatus in a printer main body can be miniaturized and compacted. Second, since the cam unit guides the tilt of the steering roller, the mechanical structure is strengthened, and connection with the driving source is easy. Third, a configuration in which tension can be applied or released by driving the auxiliary frames for supporting the steering roller using an internal driving source is adopted to facilitate loading and unloading of the belt frame and replacement of the photoreceptor belt.

Claims: A photoreceptor belt control apparatus for a printer designed to correct lateral traveling of a photoreceptor belt traveling by being supported by rollers rotatably installed on a belt frame (100), and to control tension for the photoreceptor belt, the apparatus comprising: an auxiliary frame comprising a pair of auxiliary frame members (51, 55) slidably and pivotally installed on the belt frame (100); a steering roller (61) whose ends are rotatably installed respectively on the auxiliary frame, the steering roller (61) rotating in contact with the photoreceptor belt; a shaft (65) whose ends are rotatably installed on the belt frame (100) ; a cam unit (70) installed on at least one end of the shaft (65) for controlling the inclination of the steering roller (61) by pivoting each of the auxiliary frames (51, 55) according to the rotation position of the shaft (65); and a tension control unit (80) for controlling tension to be applied to the photoreceptor belt by sliding the pair of auxiliary frame members (51, 55), the apparatus being characterised in that the tension control unit (80) comprises: an elastic biasing means (81) for elastically biasing the auxiliary frame (51, 55) against the belt frame (100); and a driving means (90) for selectively regulating an elasticity to be applied to the auxiliary frame members (51, 55) by the elastic biasing means (81), the driving means (90) comprising a driving source (91) for providing a driving force, a driving plate (93) rotatably installed on a fixing plate (105) installed between parts of the belt frame (100), and a pair of lever members (95, 97) pivotally hinge-combined with the fixing plate (105), each lever member (95, 97) being provided with one end coupled to the driving plate (93) and with its other end designed to selectively depress respective ones of the pair of auxiliary frame members (51, 55) according to the position of the driving plate (63) in the direction in which tension applied to the photoreceptor belt is released, wherein tension applied to the photoreceptor belt can be released according to the position of the driving plate (93). The photoreceptor belt control apparatus as claimed in claim 1, wherein the cam unit (70) comprises: a cam member (71, 75) installed on at least one end of the shaft (65) so that the rotation center can be eccentric from the center of the shaft (65); and an elevating guide hole (52, 56) formed on at least one auxiliary frame member (51, 55) so that the cam member (71, 75) can fit into the elevating guide hole (52, 56), the elevating guide hole (52, 56) having upper and lower surfaces contacting the outer circumference of the cam member (71, 75), wherein the auxiliary frame pivots according to the rotation of the cam member (71, 75) to control the inclination of the shaft (65). The photoreceptor belt control apparatus as claimed in claim 1 or 2, wherein the rotation of the shaft (65) is controlled by an external driving source installed in a printer main body, and a coupler (68) is further installed on at least one end of the shaft so as to mesh with the external driving source. The photoreceptor belt control apparatus as claimed in any of the preceding claims, wherein the auxiliary frame further comprises a guide bracket protruding to one side so as to contact the end of the lever member. The photoreceptor belt control apparatus as claimed in any preceding claim, wherein the elastic biasing means (81) comprises: a coupling protrusion (51b, 55b) extending from the auxiliary frame; and an elastic member (83, 85) provided with one end coupled to the coupling protrusion (51b, 55b) and the other end coupled to the end of the lever member (95, 97) to elastically bias the auxiliary frame against the belt frame (100). The photoreceptor belt control apparatus as claimed in any of the preceding claims, wherein the elastic biasing means (81') comprises: an elastic member (83) for elastically biasing the auxiliary frame (51) against the belt frame (100); a first coupling (83) protrusion (85) extending from the belt frame (100), to which one end of the elastic member (83) is coupled; and a second coupling protrusion (51b) extending from the auxiliary frame (51), to which the other end of the elastic member (83) is coupled. The photoreceptor belt control apparatus as claimed in claim 6, wherein the first coupling protrusion (85) protrudes from the belt frame (100) through a guide slot formed in the auxiliary frame and becomes the pivoting center of the auxiliary frame.

Inventors: BANG JUNG-HUN, LEE JONG-CHAN, LEE MIN-SOO, BANG, JUNG-HUN, LEE, JONG-CHAN, LEE, MIN-SOO
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1999
Main classification: G03G15
IPC codes: G03G21, B65H5, G03G15, B41J29