This application claims priority from Japanese Patent Application No. 2011-005937 filed on Jan. 14, 2011, the disclosure of which is incorporated herein by reference in its entirety.
Apparatuses consistent with one or more aspects of the present invention relate to an image forming apparatus including a plurality of photoconductor drums and a plurality of exposure units wherein each exposure unit is arranged and configured to expose a corresponding photoconductor drum.
An image forming apparatus of a particular type known in the art includes a plurality of photoconductor drums, a plurality of LED heads (exposure units), and a drum supporting member configured to support the plurality of photoconductor drums and the plurality of LED heads. Each LED head is disposed above a corresponding photoconductor drum, and the drum supporting member at which the plurality of the photoconductor drums and the plurality of LED heads are supported is configured to be movable relative to a body casing of the apparatus. Each LED head is supported by an arm that is swingably provided at the drum supporting member. Each arm is continuously biased upwardly by a spring, so that when the photoconductor drum is moved out of the body casing of the apparatus, the arm is released and swung upward by the action of the spring until it is stopped by a stopper so that the LED head with its light-emitting side facing frontward is retained in a position (retreating position) where it protrudes upward (outside) from the drum supporting member. In this way, each LED head is retreated from the corresponding photoconductor drum so that a cartridge containing the photoconductor drum can be removed easily.
In an image forming apparatus of the type mentioned above, the movement of the supporting member toward the outside of the body casing of the apparatus causes the exposure units such as LED heads to protrude outside the drum supporting member. This would cause an exposure unit to interfere with other members outside the body casing of the apparatus, or allow a user to touch the light-emitting surface of the exposure unit thereby putting dirt or scratches thereon, all of which would disadvantageously affect subsequent printing results badly.
It is thus an aspect of the present invention to provide an image forming apparatus in which exposure units such as LED heads can be retreated from the photoconductor drums while protection for the exposure units are ensured.
More specifically, according to one or more embodiments of the present invention, an image forming apparatus is provided which comprises: a easing, a plurality of photoconductor drums, a plurality of exposure units, and a drum supporting member. Each of the plurality of exposure units is configured to expose a corresponding photoconductor drum to light, to form an electrostatic latent image thereon. The drum supporting member has a pair of opposed sidewalls facing in an axial direction of the plurality of photoconductor drums. The drum supporting member is configured to support the plurality of photoconductor drums at insides of the sidewalls, and to be movable through an opening provided in the casing between a first position in which the drum supporting member is located inside the casing and a second position in which the drum supporting member is located outside the casing. The plurality of exposure units are provided at the drum supporting member. Each exposure unit is movable between an exposure position in which the exposure unit is located in proximity to the corresponding photoconductor drum and a retreating position in which the exposure unit retreated away from the corresponding photoconductor drum is positioned by a stopper, such that the exposure unit is located inside the drum supporting member regardless of whether the exposure unit is in the exposure position or in the retreating position. A motion-imparting member is provided at the drum supporting member, movably relative to the drum supporting member and is configured to act on an engageable portion of each exposure unit to thereby cause the exposure unit to move to the exposure position or to the retreating position.
The above aspect, its advantages and further features of the present invention will become more apparent by describing in detail illustrative, non-limiting embodiments thereof with reference to the accompanying drawings, in which:
A detailed description will be given of some illustrative embodiments of the present invention with reference to the drawings. In the following description, a general setup of a color printer as an example of an image forming apparatus will be described at the outset, and then features relating to the present invention will be described in detail.
Hereinbelow, the direction is designated as from the viewpoint of a user who is using (operating) the color printer. To be more specific, in
As shown in
In the front wall (at the front side) of the body casing 10, an opening 11 (see
The sheet feeder unit 20 includes a sheet feed tray 21, and a sheet conveyor system 22 configured to convey a sheet P from the sheet feed tray 21 into the image forming unit 30.
The image forming unit 30 includes four LED arrays 40 as an example of a plurality of exposure units, four process cartridges 50, a transfer unit 70 and a fixing unit 80.
Each LED array 40 is composed of a plurality of light-emitting diodes or LEDs arranged on a semiconductor chip, and configured to expose a corresponding photoconductor drum 61 to light in the main scanning direction (parallel to an axial direction of the photoconductor drum 61). Four LED arrays 40 corresponding to the four colors are configured to be in positions above and near (in proximity to) the respective same-color photoconductor drums 61, and are supported by a drawer 100 as an example of a drum supporting member, which will be described later.
The process cartridges 50 are arranged in tandem in the longitudinal (front-rear) direction. Each process cartridge 50 comprises a development cartridge 51 and a drum cartridge 60 disposed below the development cartridge 51, and is configured to be removably installed in the drawer 100.
Each development cartridge 51 includes a toner container 52 configured to store toner as an example of developer, a development roller 53 configured to supply toner stored in the toner container 52 to the photoconductor drum 61, a supply roller and a doctor blade (reference characters thereof are omitted), and other components. Four development cartridges 51 provided for the respective colors are configured to store toner of the corresponding colors, respectively, and to be in positions off to the upper front of and adjacent to the respective same-color photoconductor drums 61. Each development cartridge 51 is configured to be detachably attached to the drum cartridge 60.
Each drum cartridge 60 includes a photoconductor drum 61, a charger known in the art (reference character thereof is omitted), and other components. Four drum cartridges 60 are provided for the respective colors, and each drum cartridge 60 is configured to be detachably attached to the drawer 100.
The transfer unit 70 is disposed between the sheet feeder unit 20 and an array of the photoconductor drums 61 arranged in tandem, and includes an endless conveyor belt 71 looped around a plurality of rollers, and four transfer rollers 72. The conveyor belt 71 is disposed below and opposite to each photoconductor drum 61, and the transfer rollers 72 are disposed inside the conveyor belt 71 so that the conveyor belt 71 is held between each transfer roller 72 and the corresponding photoconductor drum 61.
The fixing unit 80 is disposed rearward of the process cartridges 50 and the transfer unit 70, and includes a heating roller 81, and a pressure roller 82 which is disposed opposite to the heating roller 81 and configured to be pressed against the heating roller 81.
In the image forming unit 30 configured as described above, first, an outer peripheral surface of each photoconductor drum 61 is uniformly charged by the corresponding charger, and is then exposed to light emitted from the corresponding LED array 40. As a result, a potential of an exposed portion is lowered, and an electrostatic latent image is formed on the photoconductor drum 61 in accordance with the image data. Thereafter, toner is supplied to the electrostatic latent image on the photoconductor drum 61 by the corresponding development roller 53, so that a toner image is carried on the photoconductor drum 61.
Next, the toner images formed on the respective photoconductor drums 61 are transferred onto a sheet P one on top of another as the sheet P fed onto the conveyor belt 71 passes through between the photoconductor drums 61 and the transfer rollers 72. The sheet P then passes through between the heating roller 81 and the pressure roller 82, and meanwhile the toner images transferred on the sheet P are thermally fixed on the sheet P.
Subsequently, the sheet P with the toner images thermally fixed thereon is ejected to the outside of the body casing 10 by a sheet output roller 90 disposed downstream relative to the fixing unit 80, and placed on a sheet output tray portion 13 formed in an upper wall 14 of the body casing 10. In this embodiment, the sheet output tray portion 13 is configured as a downwardly recessed portion disposed in the middle in the lateral direction (i.e., in a position spaced from right and left sides) of the upper wall 14 of the body casing 10. With this configuration, spaces are formed inside the body casing 10 at right and left sides of the sheet output tray portion 13 (at the both sides facing in the axial direction of the photoconductor drums 61).
To be more specific, the sheet output tray portion 13 includes a first wall 131 and a second wall 132. The first wall 131 extends from a substantially horizontal rear portion of the upper wall 14 of the body casing 10 in a downward direction perpendicular to the upper wall 14, and has an ejection port 13A for a sheet P to be ejected therethrough. The second wall 132 extends obliquely upward from a lower end of the first wall 131 toward a substantially horizontal front portion of the upper wall 14 of the body casing 10, generally in an upward-and-frontward direction, and gently curves so as to upwardly bulge as viewed in the sectional view of
Next, a structure of a drawer 100 and therearound will be described in detail.
As shown in
Each of the LED arrays 40 disposed in the drawer 100 is configured to move up and down in synchronization with the front cover 12 being swung open and closed. To be more specific, when the front cover 12 is in a closed state, each LED array 40 is located in an exposure position (the position shown in
Each LED array 40 is configured to be located inside the drawer 100 irrespective of whether the LED array 40 is in the exposure position or in the retreating position. In other words, each LED array 40 is not permitted to protrude to the outside of the drawer 100. To be more specific, each LED array 40 is configured to move in the upward-downward direction within the drawer 100. With this configuration, each LED array 40 can be protected from the user or the like.
Specifically, the drawer 100 includes a pair of opposed sidewalk 110 located on the right side and on the left side (i.e., in positions corresponding to opposite ends in an axial direction of the plurality of photoconductor drums 61), and configured to support the plurality of process cartridge 50 (the plurality of photoconductor drums 61) and the plurality of LED arrays 40 disposed between (at insides of) the sidewalls 110. As shown in
At an inside of each sidewall 110, an arc-shaped groove 111 is formed which serves to guide the corresponding process cartridge 50 being moved to an exposure-ready position (the position in which the photoconductor drum 61 included therein is ready for exposure to light emitted by the LED array 40). With this configuration, each process cartridge 50 is allowed be removably installed in the drawer 100 through an operation that causes the process cartridge 50 to move on an arcing course.
The pair of sidewalls 110 include pairs of slots 112 as an example of pass-through portions configured to support each LED array 40 in such a manner that each LED array 40 can be moved upward and downward. Each slot 112 extends in the upward-downward direction, and engages with an engageabie portion 43A (see
Each LED array 40 includes, as shown in
The engageable portions 43A protruding outward through the sidewalls 110 are, as shown in
In the following description, the members disposed in pair at the right and at the left, such as the translation cams 200 and interlocking mechanisms 300 of which details will be described later, are symmetrical in structure and arrangement with respect to a median of the drawer 100 extending in the front-rear direction, and thus one of the right and left parts will be referred to as an exemplar, while the other will not be described separately for the sake of simplicity.
The main body 210 is disposed opposite to the sidewall 110 of the drawer 100, and supported in a frontwardly and rearwardly movable manner by a plurality of the support rollers 113 provided rotatably at the sidewall 110. Although not illustrated, the sidewall 110 includes a retaining member (e.g., a member having a substantially U-shaped cross section with three surfaces in abutment with an upper side, an outer side and a lower side of the main body 210) configured to retain the main body 210 in a position opposite to the sidewall 110.
Each of the cam holes 220 includes a first end portion 221, a second end portion 222 and an intermediate slanting portion 223. The first end portion 221 is a portion engageable with the engageable portion 43A of the LED array 40 located in the exposure position. The second end portion 221 is a portion engageable with the engageable portion 43A of the LED array 40 located in the retreating position. The intermediate slanting portion 223 is a portion that connects the first end portion 221 and the second connecting portion 222 to guide the engageable portion 43A moving between the exposure position and the retreating position.
The first end portion 221 of each cam hole 220 is shaped like a slot extending in the front-rear direction and arranged to have its upper edge serving to restrict upward movement of the engageable portion 43A. To be more specific, when the LED array 40 is located in the exposure position (i.e., the position in which the LED array 40 is located when guide rollers 41A rotatably provided at the LED head 41 as shown in
The second end portion 222 of each cam hole 220 is shaped like a slot extending in the front-rear direction and arranged to have its upper and lower edges serving to restrict upward and downward movement of the engageable portion 43A. To be more specific, when the LED array 40 is located in the retreating position e.g., the position in which the LED array 40 is located when the drawer 100 has been pulled out from the body casing 10), the engageable portion 43A is supported by the lower edge of the second end portion 222. Accordingly, the LED array 40 is retained at the retreating position without moving toward the exposure position. Moreover, even when a user attempts to upwardly pull out the LED array 40 in the retreating position, the LED array 40 is restricted in its movement by the engageable portion 43A being in contact with the upper edge of the second end portion 222 (or the upper end of the slot 112).
The intermediate slanting portion 223 of each cam hole 220 is shaped like a slot extending obliquely in the upward-and-rearward direction from the rear end of the first end portion 221 to the front end of the second end portion 222. With this configuration, when the translation can 200 is moved frontward from the position shown in
The rack gear portion 230 includes a plurality of gear teeth arranged in the front-rear direction, and is configured to receive a power that is produced through the open/close operation of the front cover 12 and transmitted through the interlocking mechanism 300.
The interlocking mechanism 300 is, as shown in
The arc-shaped gear portion 310 is in the form of a segment of a circle of which the center of curvature coincides with the center of rotation of the front cover 12. The arc-shaped gear portion 310 has a toothed portion 311 that is formed on part of the outer peripheral surface of the arc-shaped gear portion 310 and is configured to mesh with the first gear 320. The first gear 320 and the second gear 330 are rotatably mounted on each sidewall 110 of the drawer 100.
With this interlocking mechanism 300 configured as described above, in operation as shown in
At an upper end portion of each sidewall 110 of the drawer 100, a guide-engaging portion 114 protruding outward in the right-left direction is formed. The guide-engaging portion 114 is a portion movably supported by a guide member 400 provided at the body casing 10, in such a manner that the guide-engaging portion 114 can move frontward and rearward. The guide-engaging portion 114 includes an elongate portion 115 extending in the front-rear direction, a protrusion 116 integrally provided at a rear end of the elongate portion 115 and shaped to downwardly protrude to a level lower than an undersurface of the elongate portion 115, and a wheel 117 rotatably provided at the protrusion 116. A level-gap bridging surface 118 formed between an undersurface of the protrusion 116 and the undersurface of the elongate portion 115 is configured as a bevel slanting in the upward-and-frontward direction. Similarly, an under surface 119 of a front end portion of the elongate portion 115 is configured as a bevel slanting in the upward-and-frontward direction.
The guide member 400 includes a lower wall portion 410, a rear wall portion 420, an upper wall portion 430, and a wheel 440. The lower wall portion 410 is contoured to fit the shape of an undersurface of the guide-engaging portion 114. The rear wall portion 420 is configured to come in contact with a rear end of the guide-engaging portion 114. The upper wall portion 430 is configured to face an upper surface of the guide-engaging portion 114. The wheel 440 is rotatably provided at a front end portion 411 of the lower wall portion 410.
With this configuration, as shown in
Thereafter, the wheel 117 of the guide-engaging portion 114 rolls on an upper surface of the lower wall portion 410 while the elongate, portion 115 of the guide-engaging portion 114 is being supported on the wheel 440, so that the drawer 100 can be pulled out straight to the front. When the protrusion 116 of the guide-engaging portion 114 comes in contact with the front end portion 411 (an upwardly protruding portion) of the lower wall portion 410, the drawer 100 stops at that position (i.e., the second position outside the body casing 10).
When the drawer 100 is brought back to the first position inside the body casing 10, the user's operation of pushing the drawer 100 causes the protrusion 116 of the guide-engaging portion 114 to be fitted into a rear-side recessed portion of the lower wall portion 410 and to come in contact with the rear wall portion 420, and the drawer 100 stops at that position (i.e., the first position inside the body casing 10).
A rear-side portion of the guide member 400 configured as described above, a rear side portion of the guide-engaging portion 114 of the drawer 100 supported by this rear-side portion of the guide member 400, and a rear-side portion of the translation cam 200 described above are all located in spaces at the right and left sides of the sheet output tray portion 13 described above. To be more specific, the rear-side portion of the guide member 400, the rear-side portion (substantially triangular portions) of the drawer 100, and the rear-side portion of the translation cam 200 are disposed to overlap the sheet output tray portion 13 as viewed in the lateral (right-left) direction, when the front cover 12 is closed to enable the printer 1 to carry out the printing operation.
More specifically, when the drawer 100 is located inside the body casing 10 (i.e., in the first position), the rear-side portions (substantially triangular portions) of the drawer 100 is disposed in a position such that the substantially triangular portions protrude from a position at or around a recess formed by the first wall 131 and the second wall 132 toward the rear (see
Accordingly, the body casing 10 can be designed to have its upper wall 14 located at a lower position without changing the depth of the sheet output tray portion 13, so that the color printer 1 can be miniaturized in its vertical dimension. Moreover, part of the drawer 100 and other components is disposed in the spaces at the right and left sides of the sheet output tray portion 13 as described above in the present embodiment, and thus the front-side portion of the guide member 400, the upper front-side portion of the drawer 100 (and the upper portion of the process cartridges 50 arranged therein), and the upper front-side portion of the translation cam 200 are disposed in the space under the second wall 132 of the sheet output tray portion 13 and the upper wall 14. Therefore, the space under the second wall 132 of the sheet output tray 13 and the upper wall 14 can be utilized effectively.
According to the present embodiment described above, the following advantageous effects can be achieved.
Since the LED arrays 40 are located inside the drawer 100 regardless of whether the LED arrays 40 are in the exposure position or in the retreating position, interference of the LED arrays 40 with the other members can be prevented, and the LED arrays 40 can be protected from being unintentionally touched by a user.
Since the translation earn 200 is provided at outsides of the pair of sidewalk 110, the structure of such a motion-imparting mechanism can be simplified in comparison with an alternative configuration in which the translation cam is provided at insides of the sidewalls, and interference of the translation earn 200 with the process cartridges 50 removably installable along the arc-shaped grooves 111 can be prevented.
Since the slots 112 configured such that each engageable portion 43A protrudes through the corresponding slot 112, and each slot 112 is configured to be engageable with the corresponding engageable portion 43A to guide the corresponding LED array 40 moving between the exposure position and the retreating position are provided, the structure can be simplified in comparison with an alternative configuration in which a hole through which the engageable portion protrudes and the member for guiding the engageable portion are provided separately.
Since each pass-through portion through which the engageable portion 43A protrudes is configured as a through hole (slot 112), the rigidity of the sidewalls 110 can be enhanced in comparison with an alternative configuration in which the pass-through portion is not closed but open to contiguously extend to the end of the sidewall is formed, for example.
Since the translation cam 200 is adopted as a motion-imparting member, the structure can be simplified in comparison with an alternative configuration in which the LED arrays are moved upward and downward by means of a linkage mechanism, for example.
Since the front cover 12 and the translation cam 200 are configured to be moved simultaneously, the ease of operation of the drawer 100 can be improved.
Since part of the drawer 100 is disposed in such a position as to overlap the sheet output tray portion 13 as viewed in the lateral direction, the body casing 10 can be miniaturized in its vertical dimension without the need to reduce the depth of the sheet output tray portion 13.
Since part of the guide member 400 and part of the translation cam 200 are disposed in the spaces at the both sides of the sheet output tray portion 13, the spaces inside the body easing 10 can be utilized efficiently.
Although an illustrative embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. Various modifications and changes may be made to the specific structures and arrangement without departing from the scope of the present invention. In the drawings referred to in the following description, substantially the same elements may be designated by the same reference characters, and a duplicate description thereof will be omitted.
In the above-described embodiment, the translation cam 200 is interlocked with the motion of the front cover 12 being opened or closed, but the present invention is not limited to this specific configuration. The translation earn may be manually moved, instead. For example, as shown in
More specifically, in this embodiment, the operating lever 500 includes a pair of right and left sector gears 510, and an handle portion 520 shaped like a letter U and attached to connect the right and left sector gears 510. Each of the pair of right and left sector gears 510 is shaped to have a toothed gear segment of which a center of curvature coincides with the center of the pivoting motion of the operating lever 500. Toothed portions 511 of the sector gears 510 mesh with the rack gear portions 230, and thus, when the operating lever 500 is lowered down, the translation cam 200 moves frontward, to thereby cause the LED arrays 40 to move to the retreating position. On the other hand, when the operating lever 500 is raised up, the translation cam 200 moves rearward, to thereby cause the LED arrays 40 to move to the exposure position.
In the above-described embodiment, the LED arrays 40 are adopted as a plurality of exposure units, but the present invention is not limited to this specific embodiment. For example, a plurality of electroluminescence elements, fluorescent elements or other light-emitting elements arranged in an array wherein each light-emitting element is caused to selectively emit light in accordance with image data may be adopted, instead. Alternatively, a single light source and a plurality of optical shutters made of liquid crystal, PLZT or the like may be provided, in which the open/close timing of the optical shutters is selectively regulated in accordance with image data to control light from the light source.
In the above-described embodiment, the slot 112 (the upper end thereof) is used as a stopper to position the retreated exposure unit in the retreating position, but the present invention is not limited to this specific configuration; for example, another member provided separately from the sidewall may be used to position the exposure unit in the retreating position. Furthermore, the interlocking mechanism may be configured as a linkage.
In the above-described embodiment, the present invention is applied to the color printer 1, but the present invention is not limited thereto; any other image forming apparatus such as a photocopier, a multifunction peripheral and the like may be configured in accordance with one or more of the embodiments of the present invention.
In describing the embodiment, a recording sheet is exemplified by a sheet P of paper, such as a cardboard, a postcard, thin paper, and the like by way of example, but the recording sheet usable in embodiments of the present invention is not limited to that made of paper; an OHP sheet may be used, for example.
In describing the embodiment, the rear end portion of the drawer 100 shaped like a triangle protruding rearward is illustrated, but the shape of the rear end portion of the drawer 100 is not limited thereto; as long as the rear end has a protruding configuration, it may be consistent with any of embodiments of the present invention.
Number | Date | Country | Kind |
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2011-005937 | Jan 2011 | JP | national |