This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2013-029672 filed Feb. 19, 2013.
The present invention relates to image forming apparatuses and exposure devices.
According to an aspect of the invention, an image forming apparatus includes an image carrier that rotates; and an exposure unit that includes multiple light emitters, a holding unit, and first contact portions, the multiple light emitters being arranged along a rotation axis direction of the image carrier, the holding unit holding the multiple light emitters, the first contact portions being positioned on the holding unit so as to sandwich the multiple light emitters therebetween, the exposure unit exposing the image carrier to light. While the image carrier is being mounted on an apparatus body, the exposure unit is moved away from the image carrier in an optical axis direction of the exposure unit as a result of the first contact portions coming into contact with the image carrier, and the exposure unit and the image carrier are positioned as a result of the first contact portions coming into contact with the image carrier.
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
Referring to the drawings, exemplary embodiments of the present invention will be described in detail below.
In the exemplary embodiments, the image forming apparatus 100 is described as a so-called tandem color printer but the present invention is not limited to this. For example, the image forming apparatus 100 may be a so-called multi-path (four cycle) color printer.
The image forming section 10 includes four image forming units 1Y, 1M, 1C, and 1K, which are arranged side by side with certain intervals therebetween. Each of the image forming units 1Y, 1M, 1C, and 1K includes a photoconductor drum 12, on which an electrostatic latent image is formed and which carries a toner image, a charging device 13, which uniformly charges the surface of the photoconductor drum 12 at a predetermined potential, an LED print head (LPH) 14, which exposes the photoconductor drum 12 charged by the charging device 13 to light on the basis of image data to form an electrostatic latent image, and a developing device 20, which develops the electrostatic latent image formed on the photoconductor drum 12 with a developer. Each of the image forming units 1Y, 1M, 1C, and 1K further includes a cleaner 16 that cleans the surface of the photoconductor drum 12 subjected to a transfer operation.
The image forming units 1Y, 1M, 1C, and 1K have the same configuration except for toners contained in the corresponding developing devices 20. The image forming units 1Y, 1M, 1C, and 1K respectively form toner images of yellow (Y), magenta (M), cyan (C), and black (K). For this reason, components of the image forming units 1Y, 1M, 1C, and 1K are distinguished from one another by adding characters of “Y”, “M”, “C”, and “K” in the following description, but these characters are not added to these components when the components do not need to be distinguished from one another. For example, when the developing device of the image forming unit 1Y is to be distinguished, the developing device is written as a “developing device 20Y”, whereas the developing device is written as a “developing device 20” if the developing device 20Y does not need to be distinguished from the developing devices 20M, 20C, and 20K. Similarly, when the image forming unit for yellow is to be distinguished, the image forming unit is written as an “image forming unit 1Y”, whereas the image forming unit is written as an “image forming unit 1” when the image forming unit does not need to be distinguished from the image forming units 1M, 1C, and 1K.
The image forming section 10 includes an intermediate transfer belt 18, a driving roller 19, first transfer rollers 21, a second transfer roller 23, and a fixing device 25. The intermediate transfer belt 18 is one to which color toner images formed by the photoconductor drums 12 of the image forming units 1 are transferred in a stacked manner. The driving roller 19 rotates the intermediate transfer belt 18. The first transfer rollers 21 sequentially transfer (first transfer) the color toner images formed by the image forming units 1 to the intermediate transfer belt 18. The second transfer roller 23 collectively transfers (second transfers) the color toner images formed on the intermediate transfer belt 18 in a stacked manner to a sheet S. The fixing device 25 fixes the second-transferred color toner images to the sheet S.
The image forming section 10 also includes a pickup roller 68 and transporting rollers 69. The pickup roller 68 picks up sheets S loaded in the sheet container 40 one after another. The transporting rollers 69 transport the sheets S picked up by the pickup roller 68. The image forming section 10 also includes an exit sensor 70 that detects when a sheet S to which toner images have been fixed by the fixing device 25 passes thereby. These components are disposed in a housing 90.
In the image forming apparatus 100 according to the exemplary embodiments, image data input through the PC 200 or the image reading device 300 is subjected to predetermined image processing by the image processor 6 and then transmitted to each image forming unit 1 via an interface, not illustrated. Thereafter, for example, in the image forming unit 1K that forms a black (K) toner image, the photoconductor drum 12 is uniformly charged by the charging device 13 at a predetermined potential while rotating in the direction of the arrow A in
The toner images of the corresponding colors formed by the image forming units 1 are sequentially and electrostatically sucked by the first transfer rollers 21 and transferred to the surface of the intermediate transfer belt 18 that moves in the direction of the arrow B in
Meanwhile, the sheets S loaded in the sheet container 40 are picked up by the pickup roller 68. Each sheet S picked up by the pickup roller 68 is fed to the second transfer portion Tr by the transporting rollers 69 at the timing when the superposed toner image is transported to the second transfer portion Tr. The superposed toner image is electrostatically transferred as a whole to the sheet S that has been transported to the second transfer portion Tr by the transporting rollers 69 with an effect of a transfer electric field formed by the second transfer roller 23.
The sheet S to which the superposed toner image has been electrostatically transferred is separated from the intermediate transfer belt 18 and transported to the fixing device 25. The toner image on the sheet S transported to the fixing device 25 is subjected to a fixing operation with heat and pressure by the fixing device 25 and thus fixed to the sheet S. The sheet S to which the image is fixed is further transported by the transporting rollers 69. After being detected by the exit sensor 70, the sheet S is ejected to the ejected-sheet holder 46 and stacked on other sheets S.
In this manner, the image forming apparatus 100 repeats the image formation cycle as many times as the number of sheets to be printed.
Referring now to
As illustrated in
In the following description, the longitudinal direction (main scan direction) of the LPH 14 is defined as an X direction, the optical axis direction of light that travels from the LPH 14 to the photoconductor drum 12 (light emission direction) is defined as a Z direction, and the direction that is perpendicular to the X and Z directions is defined as a Y direction. In addition, the left side of
Referring now to
As illustrated in
The housing 90 also includes flat springs 93, which urge rear end portions of the photoconductor drums 12 toward the corresponding LPHs 14 (downward in
As illustrated in
The LPH-14 side of each photoconductor-drum supporting hole 96 in the Z direction is formed into a V shape. Specifically, each photoconductor-drum supporting hole 96 has a tapered portion 96a in which the width in the Y direction is tapered toward the LPH 14 in the Z direction. When the photoconductor drum 12 is pressed against the tapered portion 96a by the urging force of the flat spring 93, the photoconductor drum 12 becomes immobile in the Z direction and in the Y direction.
An end portion of each frame 50 is fitted into the corresponding frame supporting hole 99 and fixed to the supporting plate 91 by welding or by other ways. On the other hand, each LPH 14 held in the corresponding frame 50 is movable in the Z direction (this configuration will be described in detail below). The frame 50 and the housing 90 may be regarded as an apparatus body.
Referring now to
As illustrated in
The photoconductor drum 12 and the LPH 14 are in contact with each other at two points (see
Referring now to
The LPH 14, which is an example of an exposure unit, includes a light-emitting chip array 146 (see
The LPH 14 supports the circuit board 142 and the rod lens array 143 and includes a resin-made holder 145 that shields the light-emitting chip array 146 disposed on the circuit board 142 from outside. Here, the holder 145 includes a top surface 145a, on which the rod lens array 143 is disposed, and side surfaces 145b extending in the longitudinal direction of the holder 145.
The holder (holding unit) 145 includes multiple ribs (first contact portions or guide portions) 141, which protrude in the Z direction from the top surface 145a at both end portions in the X direction. Specifically, as illustrated in
As illustrated in
The holder 145 also includes supportable portions 147, which protrude from the side surfaces 145b in the Y direction. Specifically, as illustrated in
Referring now to
The first rib 141a to the third rib 141c respectively include inclined surfaces 149a to 149c, which are inclined so as to become increasingly separated from the top surface 145a as they extend from an upstream side to a downstream side in a direction in which the photoconductor drum 12 is inserted (see the arrow C and this direction is hereinafter referred to as insertion direction). The first rib 141a to the third rib 141c also have top surfaces 151a to 151c, respectively, which face the photoconductor drum 12. The first rib 141a and the third rib 141c respectively include tapered portions 153a and 153c at their upstream end portions in the insertion direction. The width of each of the tapered portions 153a and 153c in the Y direction is tapered from the downstream side to the upstream side in the insertion direction.
The first rib 141a and the second rib 141b are separated from each other in the Y direction. The height of the first rib 141a from the top surface 145a of the holder 145 is larger than the height of the second rib 141b. In addition, the heights of the first rib 141a and the second rib 141b from the top surface 145a are larger than the height of the third rib 141c.
Referring now to
As illustrated in
As illustrated in
Referring now to
As illustrated in
As illustrated in
As illustrated in
Here, the dimension of each of the first through-hole 155a to the third through-hole 155c in the Z direction is determined such that the corresponding one of the first supportable portion 147a to the third supportable portion 147c inserted into itself is movable in the Z direction and such that the frame 50 is not in contact with the corresponding one of the first supportable portion 147a to the third supportable portion 147c in the state where the position of the LPH 14 with respect to the photoconductor drum 12 is fixed (to be described in detail, below).
In the example illustrated in
Here, when the LPH 14 is in the state of not being pressed by the photoconductor drum 12, the position of the LPH 14 in the Z direction is temporarily determined as a result of the first supportable portion 147a to the third supportable portion 147c respectively coming into contact with a first ceiling portion 158a to a third ceiling portion 158c.
Referring now to
Each photoconductor drum 12, which is an example of an image carrier, includes a photoconductor drum body 120 and a shaft 122, which is a rotation shaft of the photoconductor drum body 120. An electrostatic latent image is formed on a surface of the photoconductor drum body 120 by the LPH 14 and the photoconductor drum body 120 holds a toner image. Each photoconductor drum 12 also includes a photoconductor-drum side coupling 125 and a covering member 127, which covers the photoconductor drum body 120. The photoconductor-drum side coupling 125 receives driving force from the housing 90 at the downstream end portion in the insertion direction (see the arrow C in
Each covering member 127 has a positioning hole 121 on an upstream side in the insertion direction (see the arrow C in
Referring now to
The rear bearing 131 and the front bearing 133 are made of resin and includes contact portions (second contact portions) 135, which protrude toward the LPH 14 and come into contact with the LPH 14. Specifically, as illustrated in
The first bearing-side contact portion 135a has a groove 137a that extends in the X direction. The width of the groove 137a in the Y direction corresponds to the width of the first rib 141a in the Y direction. Similarly, the third bearing-side contact portion 135c has a groove 137c that extends in the X direction. The width of the groove 137c in the Y direction corresponds to the width of the third rib 141c in the Y direction.
The first bearing-side contact portion 135a and the third bearing-side contact portion 135c are formed on one side portion of the photoconductor drum 12 in the Y direction.
The heights of the first bearing-side contact portion 135a and the second bearing-side contact portion 135b, which are the contact portions 135 on the rear side, from the shaft 122 (see L1 in
Referring now to
First, a LPH 14 and a frame 50 are inserted into the housing 90. Here, the LPH 14 and the frame 50 may be regarded as an exposure device. Then, as the guided portion 129 of the photoconductor drum 12 is guided by the guide rails 95, the photoconductor drum 12 enters the housing 90 (see the arrow C in the drawings) while the orientation of the photoconductor drum 12 remain unchanged. Thereafter, the first bearing-side contact portion 135a of the photoconductor drum 12 comes into contact with the first rib 141a of the LPH 14 positioned so as to protrude into a passage (insertion passage) along which the photoconductor drum 12 enters the housing 90.
At this time, the first bearing-side contact portion 135a is moved along the inclined surface 149a of the first rib 141a and rises to the top surface 151a of the first rib 141a while an impact (damage) exerted on the LPH 14 is kept low. While the first bearing-side contact portion 135a is in the state of rising to the top surface 151a, the first bearing-side contact portion 135a moves the first rib 141a by applying a force to the first rib 141a in a direction away from itself in the Z direction (see the arrow D in the drawings). Thus, the position of the LPH 14 with respect to the photoconductor drum 12 is fixed. The position of the LPH 14 is an example of a predetermined position of the exposure unit.
Similarly, the second bearing-side contact portion 135b and the third bearing-side contact portion 135c respectively rise to the top surface 151b and the top surface 151c and move the second rib 141b and the third rib 141c by applying forces to the second rib 141b and the third rib 141c in a direction away from itself in the Z direction (see the arrow D in the drawings).
When the photoconductor drum 12 has been inserted into the housing 90, the photoconductor-drum side coupling 125 positioned at the end (downstream side end in the insertion direction) of the photoconductor drum 12 becomes engaged with the housing-side coupling 97.
Here, since the first bearing-side contact portion 135a is guided by the tapered portion 153a when the first bearing-side contact portion 135a rises to the top surface 151a, the first rib 141a is fitted into the groove 137a of the first bearing-side contact portion 135a. More specifically, the first bearing-side contact portion 135a is disposed so as to stride across the first rib 141a in the Y direction (see
Similarly, the third bearing-side contact portion 135c is disposed so as to stride across the third rib 141c in the Y direction. Thus, the position of a front portion of the LPH 14 with respect to the photoconductor drum 12 is prevented from being changed in the Y direction.
Although not described above, the housing 90 includes a positioning protrusion 98 (see
When the photoconductor drum 12 has been inserted into the housing 90, the hook 123 becomes engaged with the housing 90. Thus, movement of the photoconductor drum 12 with respect to the housing 90 in the X direction is restricted. In the example illustrated in the drawings, the position of the photoconductor drum 12 in the X direction is fixed by using the hook 123. However, the housing 90 may have a configuration in which an upstream-side end portion of the photoconductor drum 12 in the insertion direction is pressed downstream by using, for example, a plate member, such as an openable cover.
Referring now to
As illustrated in
In the state where the position of the LPH 14 with respect to the photoconductor drum 12 is fixed, the first supportable portion 147a to the third supportable portion 147c are respectively disposed in the first through-hole 155a to the third through-hole 155c without being in contact with the frame 50 and thus are not pressed by the frame 50. More specifically, in the exemplary embodiment, the first supportable portion 147a to the third supportable portion 147c are separated from a first bottom portion 156a to a third bottom portion 156c of the first through-hole 155a to the third through-hole 155c. Thus, the position of the LPH 14 is not changed due to the first supportable portion 147a to the third supportable portion 147c respectively coming into contact with the first bottom portion 156a to the third bottom portion 156c of the first through-hole 155a to the third through-hole 155c.
In the example illustrated in the drawings, the sum of the heights of the first rib 141a and the first bearing-side contact portion 135a in the Z direction, the sum of the heights of the second rib 141b and the second bearing-side contact portion 135b in the Z direction, and the sum of the heights of the third rib 141c and the third bearing-side contact portion 135c in the Z direction coincide with one another. Thus, in the state where the first rib 141a to the third rib 141c are respectively in contact with the first bearing-side contact portion 135a to the third bearing-side contact portion 135c, the rod lens array 143 and the photoconductor drum body 120 are parallel to each other.
The configuration in which each rib 141 has a corresponding one of the inclined surfaces 149a to 149c has been described above. However, the present invention is not limited to this configuration as long as the photoconductor drum 12 directly pushes the LPH 14 away as the photoconductor drum 12 is being inserted. Thus, a configuration in which the contact portions 135 each have an inclined surface or in which both of the ribs 141 and the contact portions 135 have inclined surfaces may be employed, for example.
A configuration including a so-called lifting mechanism that is different from the configuration according to the exemplary embodiment is conceivable. Specifically, in this configuration, the LPH 14 is movable between a use position and a retract position. After the photoconductor drum 12 is inserted into the housing 90 while the LPH 14 is in the retract position, the LPH 14 is moved to the use position by, for example, a users' operation. However, the configuration according to the exemplary embodiment is simpler than the configuration including the lifting mechanism. Moreover, the configuration according to the exemplary embodiment dispenses with an operation of additionally moving the LPH 14 when the photoconductor drum 12 is inserted into or removed from the housing 90.
Referring now to
As illustrated in
Referring now to
On the rear side, the LPH 14 includes a first rib 241a and a first supportable portion 247a, the frame 50 includes a first spring member 257a and a first through-hole 255a, and a rear bearing 231 includes a first bearing-side contact portion 235a. On the front side, the LPH 14 includes a second rib 241b and a second supportable portion 247b, the frame 50 includes a second spring member 257b and a second through-hole 255b, and a front bearing 233 includes a second bearing-side contact portion 235b.
The first rib 241a, the second rib 241b, the first supportable portion 247a, and the second supportable portion 247b are formed on one side (on the right side in
Referring now to
As illustrated in
As illustrated in
Referring now to
As illustrated in
For this reason, in the state where the LPH 14 is not being pressed by the photoconductor drum 12, as illustrated, the holder 245 (see
As illustrated in
As illustrated in
Here, as illustrated in
When the third supportable portion 247c comes into contact with the third ceiling portion 256c of the third through-hole 255c and receives frictional force, the LPH 14 is prevented from moving in the Y direction (see the arrow F in
In the exemplary embodiment, bending of the LPH 14 due to an application of an external force to the LPH 14 from another component is prevented compared to, for example, a configuration in which a center portion of the LPH 14 in the X direction is fixed by being held by another component.
The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
Number | Date | Country | Kind |
---|---|---|---|
2013-029672 | Feb 2013 | JP | national |