Patent Application
20140091513
This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2012-216676 filed on Sep. 28, 2012. The entire subject matter of the application is incorporated herein by reference.
1. Technical Field
Aspects of the present invention relate to an image forming apparatus.
2. Prior Art
A conventional image forming apparatus typically has a main body, a sheet placing part, a sheet supply roller and an image forming unit. In the main body, a sheet feed path through which a sheet is fed is formed. On the main body, an opening through which inside and outside of the image forming apparatus communicate. The sheet placing part is defined inside the main body, and sheets, which are inserted in the main body are placed thereon. The sheet ejection roller is arranged at a position opposing to the sheet placing part, and feeds the sheets placed on the sheet placing part toward the sheet feed path. The image forming unit is also provided inside the main body, and forms images on the sheets.
With the above configuration, the conventional image forming apparatus is configured to feed sheets one by one and form an image on each sheet.
According to the conventional image forming apparatus, the sheets inserted inside the main body through the opening should be sufficiently inserted, in a sheet feed direction, so that part of the sheets contact the sheet supply roller. In such an image forming apparatus, the sheet supply roller is exposed to outside the main body through an opening on the downstream side of the sheet supply roller. Therefore, in such an image forming apparatus, a leading end of the sheet may contact the supply roller when a user attempt to insert the sheet in the main body and the sheet may be buckled.
In consideration of the above problem, aspects of the invention provide an improved image forming apparatus which is capable of suppressing buckling of the sheets when the user attempts to place the same on the sheet placing part.
According to aspects of the invention, there is provided an image forming apparatus, which has a main body having a sheet feed path configured such that a sheet is fed along the sheet feed path and an opening through which an inside and an outside of the main body communicate with each other, a sheet placing part defined in the main body and configured such that the sheet inserted, through the opening, in the main body is placed on the sheet placing part, a supply roller arranged to face the placing part and configured to feed the sheet placed on the sheet placing part in a sheet feed direction toward the sheet feed path, a frame arranged to face the sheet placing part and configured to support the supply roller, the frame having a protruded part which is protruded, in the sheet feed direction, on an opening side with respect to the supply roller, and an image forming unit provided inside the main body and configured to form an image on the sheet, and the protruding part has an inclined surface facing the sheet placing part and inclined such that a distance between the inclined surface and the sheet placing part becomes gradually smaller toward the supply roller.
In the image forming apparatus according to aspects of the invention, a frame is arranged to face the sheet placing part. The frame is configured to support the supply roller and has a protruded part, which protrudes, in a sheet feed direction in which the sheet is supplied toward the sheet feed path, on the opening side with respect to the supply roller. Further, on a surface of the protruded part, facing the sheet placing part, an inclined surface is formed. The inclined surface is configured such that a part on the inclined surface closer the sheet supply roller is closer to the sheet placing part. Therefore, according to the image forming apparatus, when the sheet is inserted in the main body and fed in the feeding direction so that the sheet contacts the sheet supply roller, it is possible to prevent the leading end of the sheet hits the sheet supply roller since the leading end of the sheet contacts the inclined surface and proceeds as it becomes closer to the sheet placing part.
Therefore, with the image forming apparatus according to the invention, curving of the sheet placed on the sheet placing part can be suppressed.
Hereinafter, an exemplary embodiment will be described, referring to the drawings.
An image forming apparatus 1 shown in
<Schematic Structure of Image Forming Apparatus>
The image forming apparatus 1 is a monochrome laser printer. As shown in
The main body 8 has a substantially box-like shape. A rear side surface 8R is higher than a front side surface 8F, and an upper surface of the main body 8 is formed to have a step so that a rear side portion of the main body 8 is higher than a front side portion of the main body 8 (see
As shown in
A front side portion of the body cover 7, a sheet ejection tray 72 is formed on the upper surface thereof. Further, on the body cover 7, an auxiliary tray 72A is provided. The auxiliary tray 72A is displaceably supported by the body cover 7 so as to be located at a position where the auxiliary tray 72A extends frontward with respect to the ejection tray 72 as shown by two-dotted line in
As shown in
As shown in
As shown in
As shown in
As shown in
Specifically, as shown in
As shown in
A protruded part 51 is a part of the feeding unit holding frame 50, forwardly protruded from the main part 55, and extending from the left end part 51A and the inclined part 51C to the right end part 51B and the inclined part 51D. As shown in
As shown in
Specifically, ribs 53E, which are arranged to overlap the sheet supply roller 11 in the right-and-left direction but spaced in the front-and-rear direction, extend in the right-and-left direction which is parallel to a direction in which the front end part 51E extends. Ribs 53C which overlap the inclined parts 51C in the right-and-left direction, but spaced therefrom in the front-and-rear direction extend in parallel with the inclined parts 51C. Ribs 53D which overlap the inclined part 51D in the right-and-left direction but spaced in the front-and-rear direction extend in parallel with the inclined parts 51D. Ribs 53A located between the ribs 53E and ribs 53C, in the right-and-left direction, are formed so that inclination angle thereof with respect to the right-and-left direction is smaller than that of the ribs 53C. Ribs 53B located between the ribs 53E and ribs 53D, in the right-and-left direction, are formed so that inclination angle thereof with respect to the right-and-left direction is smaller than that of the ribs 53D. In other words, the ribs arranged at farther positions with respect to the sheet supply roller 11, in the right-and-left direction, are formed such that the inclination angle with respect to the right-and-left direction is greater.
As shown in
As shown in
The sheet feed unit 10 includes the sheet supply roller 11, a separation roller 12 and a separation pad 13. The sheet supply roller 11 and the separation roller 12 are accommodated inside a receiving portion 54 of the feeding unit holding frame 50, in the vicinity of the rear surface 8R.
More specifically, as shown in
As shown in
The right end portion of the shaft 15 protrudes inside the receiving portion 54 by a predetermined amount, and engages with a separation roller 12. Inside the receiving portion 54, a roller holder 17 is provided. The roller holder 17 is inserted in the receiving portion 54, and supported by the feeding unit holding frame 50 with the shaft 15 being inserted. The roller holder 17 supports the separation roller 12 by surrounding the same from the right and left sides. Further, the roller holder 17 extends frontward and rotatably supports the sheet supply roller 11. To the roller holder 17, a transmission gear train 16 is provided. The transmission gear train 16 transmits a rotation of the separation roller 12 to the sheet supply roller 11.
The left end portion 15A of the shaft 15 extends on the left side of the left side end 50A of the feeding unit holding frame 50, and the driving gear 10G is secured at the left end portion 15A of the shaft 15. A rotational driving force is input from a drive source (e.g., a motor) 100 to the driving gear 10G, and the rotational driving force is transmitted to the separation roller 12 through the shaft 15.
As shown in
A separation pad 13 is provided on the inclined surface 59D at a position to face the separation roller 12 with the feeding path P1 being located therebetween. The separation pad 13 is urged toward the separation roller 12.
The drive roller 14A and the pinch roller 14B are arranged above the separation roller 12 and the separation pad 13, respectively, and face each other with the sheet feed path P1 being located therebetween.
Specifically, one pair of the drive roller 14A and the pinch roller 14B is provided on the left side of the feeding roller 11, and another pair is provided on the right side of the feeding roller 11.
The drive roller 14A is rotatably supported by the feeding chute 59. A rotational driving force is input from the driving source 100 inside the main body 8 to the drive roller 14A so that the supply roller 11 and the separation roller 12 rotate synchronously.
As shown in
As shown in
As shown in
The front end part 51E extends on the left side of the left side pinch roller 14B. Further, the front end part 51E extends on the right side of the right side pinch roller 14B. With this configuration, as the left end part 50A and the right end part 50B are connected to the side frames 58A and 58B, respectively, the feeding unit holding frame 50 is hardly bendable.
As shown in
The platen 110 is a planar plate-like member which extends, at a bottom portion inside the main body 8, from the front surface 8F side toward the rear surface 8R side. A plurality of sheets 99, which are inserted in the main body 8 through the opening, are placed in a stacked manner. When the tray 120 is located at the open position, the tray 120 is located on the front side with respect to the platen 110 and supports a portion of the stacked sheets 99 protruded frontward from the opening 89 from below.
As shown in
As shown in
Below the platen 110, a displacing mechanism 119 is provided. The displacing mechanism 119 extends substantially horizontally toward the rear side. When he image forming apparatus 1 forms the image formation process, the displacing mechanism is controlled by a controlling unit (not shown) to rotate and is displaced to be upwardly inclined toward the rear side as shown in
The image formation process is performed on the sheet 99 placed on the platen 110 as follows. The displacing mechanism 119 rotates and the platen 110 is moved to the closer position. Then, the uppermost sheet 99 placed on the platen 110 contacts the sheet supply roller 11. The sheet supply roller 11 is controlled by the not-shown controlling unit and rotates with contacting the sheet 99. Then, the sheet 99 on the platen 110 is fed from the front side toward the rear side. With this control, the sheet supply roller 11 feeds the sheet 99 on the platen 110 to the sheet feed path P1. According to the exemplary embodiment, the direction in which the sheet 99 is fed to the sheet feed path P1 is the front-and-rear direction. An upstream side in the sheet feed direction is the front surface 8F side of the main body 8, while a downstream side in the sheet feed direction is the rear surface 8R side of the main body 8.
As shown in
As shown in
Incidentally, as shown in
As shown in
By pinching the operation part 170 and moving the same in the right-and-left direction, the side guide 130B slides integrally in the right-and-left direction. Then, via the rack-and-pinion mechanism 139, the moving force to the right side guide 130B is transmitted to the left side guide 130A. Thus, the side guides 130A and 130B mutually approach or separate on the pressure plate in the right-and-left direction. As above, with the side guides 130A and 130B, positioning of the sheet 99 can be done for a sheet width range of a first width W1 to a second width W2.
According to the exemplary embodiment, the first width W1 corresponds to the width of an A4 sheet (i.e., 210 mm) and the second width W2 corresponds to the width of a letter size sheet (i.e., 216 mm). Thus, the positions of the side guides 130A and 130B are switched between the positions for the A4 size and the positions for the letter size, on the platen 110.
As shown in
As shown in
The process cartridge 21 is arranged at an upper portion of the feeding unit holding frame 50. The process cartridge 21 is a box-like member extending in the right-and-left direction. A vertical portion of the sheet feed path P1 is included in the process cartridge 21. Inside the process cartridge 21, a photoconductive drum 22, a transfer roller 27, a developing roller 23, a supplying roller 24, a container 26, a charter 25 and the like are included.
The photoconductive drum 22 is a cylindrical member extending in the right-and-left direction. The photoconductive drum 22 faces the vertical part of the sheet feed path P1 from the front side. The transfer roller 27 faces the photoconductive drum 22 with the vertical part of the sheet feed path P1 located therebetween. The photoconductive roller 22 and the transfer roller 27 rotate synchronously with sandwiching the sheet 99, which is fed through the vertical part of the sheet feed path P1, at the nip therebetween. The container 26 contains toner to be supplied to the photoconductive drum 22. The supplying roller 24 supplies the toner to the developing roller 23 from the container 26. The developing roller 23 supplies the toner to the photoconductive drum 22 to develop an electrostatic latent image formed on the photoconductive drum 22. The charger 25 extends in the right-and-left direction and is arranged to be parallel with the photoconductive drum 22 with being spaced upward from the photoconductive drum 22. The charger causes the photoconductive drum 22 to be positively charged by corona discharging.
The scanner unit 29 is arranged on a front side of the process cartridge 21. The scanner unit 29 includes a laser source, a polygonal mirror, an fθ lens, mirrors and the like, and emits a laser beam to the photoconductive drum 22 located on the rear side of the process cartridge 21.
The fixing unit 30 is arranged on an upper side of the photoconductive drum 22 and the transfer roller 27 at the vertical part of the sheet feed path P1. The fixing unit 30 includes a heat roller 31 facing the sheet feed path P1 from the front side, and a pressure roller opposing to the heat roller 31 with the sheet feed path P1 located therebetween.
A pair of ejection rollers 19A and 19B is arranged at a most downstream side of the sheet feed path P1. That is, the pair of ejection rollers 19A and 19B is arranged at a position where the sheet feed path P1 changes its extending direction toward the front side, and faces the ejection opening 71. The ejection roller 19A and the ejection roller 19B face each other with the sheet feed path P1 located therebetween.
<Inclined Surface and Guiding Surface>
As shown in
As shown in
As shown in
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As shown in
As shown in
At rear side ends of the recesses 51F and 51h, guide surfaces 51G and 51I are formed. The guide surfaces 51G and 51I are downwardly inclined and guide the left and right side ends of the sheet 99 toward the feeding path P1. By the guide surfaces 51G and 51H, even if the left and right side ends of the sheet flip-flop, the sheet 99 can be fed toward the feeding path P1 in stabilized manner.
<Image Forming Process>
The image forming apparatus 1 is configured to form an image on the sheet 99 placed on the platen 110 as follows. When the not-shown control unit starts controlling, the displacing mechanism 119 move the platen 110 from the spaced position shown in
Next, the supply roller 11, the separation roller 12, the drive roller 14A, the image forming unit 20, the scanner unit 29, the fixing unit 30 and the pair of ejection rollers 19A and 19B operate in an associated manner. Then, the supply roller 11 feeds the sheet 99 contacting therewith toward the sheet feed path P1. the inclined surface 59D of the feeding chute 59 contacts the sheet 99 being fed from below, and guides the sheet 99 so that the sheet 99 is fed along the sheet feed path P1. The separation roller 12, in association with the separation pad 13, separates the sheets 99 to be fed one by one. The drive roller 14A and the pinch roller 14B feed the separated sheet 99 toward the process cartridge 21.
Next, the photoconductive drum 22 rotates and its circumferential surface is uniformly charged by the charger 25. Then, the photoconductive drum 22 is exposed to the laser beam emitted by the scanner unit 29. Thus, the scanner unit 29 forms an electrostatic latent image, which corresponds to the image to be formed on the sheet 99, on the circumferential surface of the photoconductive drum 22. The developing roller 23 and the supply roller 24 supply the toner from the container 26 to the electrostatic image on the circumferential surface of the photoconductive drum 22. Thereby, a toner image corresponding to the electrostatic image is carried on the surface of the photoconductive drum 22. As the circumferential surface of the photoconductive drum 22, which is being rotated, contacts the sheet 99, which is being fed, and a negative voltage applied to the transfer roller 27 acts on the sheet 99, the toner image carried by the photoconductive drum is transferred onto the sheet 99.
The sheet 99 on which the toner image 99 has been transferred is further fed substantially vertically along the sheet feed path P1 and reaches the fixing unit 30. At the fixing unit 30, the heat roller 31 applies heat to the sheet 99, while the pressure roller 32 urges the sheet 99 toward the heat roller 31 (i.e., the sheet 99 is nipped between the heat roller 31 and the pressure roller 32 and a pressure is applied to the sheet 99). With this configuration, the fixing unit 30 fixes the toner image on the sheet 99. Thereafter, the sheet 99 is fed by the pair of ejection rollers 19A and 19B, and ejected toward the ejection tray 72 through the ejection opening 71. Then, the image forming apparatus 1 finishes the image forming process to form an image on the printing sheet.
<Effects>
The image forming apparatus 1 according to the exemplary embodiment is configured such that the protruded port 51 is protruded on the opening 89 side with respect to the sheet supply roller 11 in a direction where the sheet 99 is fed toward the sheet feed path P1, or in the front-and-rear direction, as shown in
Therefore, the image forming apparatus 1 according to the exemplary embodiment can suppress bending of the sheet 99 that is placed on the platen 110.
In the image forming apparatus 1 according to the embodiment, as shown in
In the image forming apparatus 1 according to the exemplary embodiment, a reactive force R1 of the compression coil spring 14C which urges the pinch roller 14B toward the drive roller 14A acts such that a central part, in the right-and-left direction, of the feeding unit holding frame 50 is deflected, in the front-and-rear direction, toward the opening 89. In the image forming apparatus 1, the main body 55 of the feeding unit holding frame 50 is connected to the right and left side frames 58B and 58A at the right and left end sides 50B and 50A, respectively. The protruded part 51 of the feeding unit holding frame 50 protrudes, in the front-and-rear direction, on the opening 89 side with respect to the sheet supply roller 11. The protruded part 51 is formed continuously from a left side of the left-side pinch roller 14B to a right side of the right-side pinch roller 14B. Therefore, the protruded part 51 serves to receive the reactive force R1 of the compression coil spring 14C and reinforce the feeding unit holding frame 50. As a result, in the image forming apparatus 1, it is ensured that deformation of the feeding unit holding frame 50 can be suppressed. Further, in the image forming apparatus 1, since the feeding unit holding frame 50 is made of resin, the above-described shape of the feeding unit holding frame 50 can easily be formed.
Further, as shown in
In the image forming apparatus 1, the guiding part 52 protrudes, with respect to a side part 54E of the opening 89 of the receiving portion 54 in the front-and-rear direction, as show in
In the description above, the present invention is described with reference to the exemplary embodiment. It should be noted that the present invention should not be limited to the configuration of the above-described exemplary embodiment, but can be modified in various ways without departing from the scope of the invention.
For example, in the embodiment, the right and left guide portions 52 are formed to overlap the right and left end portions of the sheet supply roller 11 when viewed from the sheet feed direction. However, the invention needs not be limited to such a configuration. For example, as shown in
The sheet placing unit can be formed to be rockable between the spaced position and the close position, or can be configured to translate between those positions. Further, the sheet placing unit may be configured to be moved between the close position and the spaced position with being kept to incline downwardly. Further, a direction in which the pressure plate is displaceable needs not be limited to a vertical (i.e., the up-and-down) direction, but can be inclined with respect to the up-and-down direction. Further, the sheet placing unit may be configured to unmovable and arranged at a fixed position.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-216676 | Sep 2012 | JP | national |
