Image forming device

Abstract

To facilitate adjustment to a position suitable for a plurality of types of recording media having different thicknesses.SOLUTION: An image forming device includes: a paper feed roller 161 that rotates around a rotation axis; a pair of holders 171A and 171B that support a paper feed roller shaft 162 at both ends of the paper feed roller 161 and are attached to a fixed member 11B of a main body frame 11; a front separating member 163 attached to the main body frame 11 so as to face the paper feed roller 161; and an adjustment member 181 having a plurality of selection portions each having an upper surface at a different height from a common bottom surface, any one of the plurality of selection portions being disposed between the fixed member 11B and the holder 171A.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] This invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with a paper feed roller for conveying a recording medium.

Background Art

[0002] In an image forming apparatus, a plurality of recording media are placed on a paper feed tray in a stacked state. The image forming apparatus sequentially conveys the recording media one by one from the uppermost recording medium of the plurality of recording media and forms an image on the recording medium. For example, Japanese Patent Application Laid-Open No. 2008-127196 discloses a paper feed mechanism including a paper feed roller, a separating member that presses against the paper feed roller, a biasing member that biases the separating member in the direction of the paper feed roller, and a biasing force adjusting means for adjusting the biasing force of the biasing member. The biasing force adjusting means includes a receiving base having an engaging claw that supports one end of the biasing member, and a holding plate having continuous or discontinuous protrusions with different heights. The receiving base is locked to the holding plate by engaging the engaging claw of the receiving base with the protrusion of the holding plate, and the biasing force of the biasing member is adjusted by selecting the protrusion with which the engaging claw is engaged.

[0003] In the paper feed mechanism described in Japanese Patent Application Laid-Open No. 2008-127196, since the biasing member biases the separating member at a single point of the separating member, the force with which the separating member biases the paper feed roller may be different at a plurality of positions in the rotational axis direction of the paper feed roller. For this reason, the force with which the separating member biases the paper feed roller may not be stable. Further, when the biasing force applied to the separating member is low, thick paper abuts against the separating member and receives resistance, so that it cannot be conveyed. When the biasing force is high, a plurality of thin papers are sent overlapping each other. For this reason, if the biasing force is adjusted according to the thick paper, the thin paper may be double-fed, and if the biasing force is adjusted according to the thin paper, the thick paper may not be conveyed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] One object of the present invention is to provide an image forming apparatus that facilitates the operation of adjusting to a position suitable for a plurality of types of recording media having different thicknesses.

MEANS FOR SOLVING THE PROBLEMS

[0006] According to an aspect of the present invention for achieving the above object, an image forming apparatus includes a paper feed roller that rotates around a rotation axis, a holding portion that pivotally supports the rotation axis and is attached to a main body frame, a guide member that is attached to the main body frame facing the paper feed roller, and an adjustment member that has a plurality of selection portions each having a plurality of upper surfaces with different heights from a common bottom surface, and any one of the plurality of selection portions is disposed between the main body frame and the holding portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]

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Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0009] FIG. 1 is a perspective view showing an example of the appearance of an MFP in one embodiment of the present invention. The MFP 100 includes an automatic document feeder 120, a document reading unit 130, an image forming unit 140, a paper feeding unit 150, and an operation panel 110. The document reading unit 130 reads a document. The automatic document feeder 120 conveys the document to the document reading unit 130. The image forming unit 140 forms an image on a sheet or the like based on image data. The image data includes image data included in a long print job and image data output by the document reading unit 130 reading a document. The paper feeding unit 150 supplies a recording medium to the image forming unit 140. The recording medium includes a sheet-like resin film such as an OHP film in addition to paper. Hereinafter, the case where the recording medium is paper will be described as an example. The operation panel 110 is a user interface that provides information to the user or accepts operations input by the user.

[0010] The automatic document feeder 120 automatically conveys a plurality of documents set on the document tray one by one to a predetermined document reading position set on the platen glass of the document reading unit 130. The automatic document feeder 120 discharges the document from which the image formed on the document has been read by the document reading unit 130 to the document discharge tray. The document reading unit 130 includes a light source that irradiates light onto the document conveyed to the document reading position, and a photoelectric conversion element that receives the light reflected by the document, and scans a document image according to the size of the document. The photoelectric conversion element converts the received light into image data, which is an electrical signal, and outputs it to the image forming unit 140.

[0011] The paper feeding unit 150 includes paper feed trays 151 to 153 and a manually insertable tray 154 that can be opened and closed. In FIG. 1, the manually insertable tray 154 in the closed state is shown. The paper feeding unit 150 conveys the paper stored in the paper feed trays 151 to 153 or the paper placed on the manually insertable tray 154 to the image forming unit 140. The image forming unit 140 forms an image by a well-known electrophotographic method. The image forming unit 140 forms an image on the paper conveyed by the paper feeding unit 150, and discharges the paper on which the image has been formed to the paper discharge tray 159.

[0012] FIG. 2 is a schematic side view showing a partial internal configuration of the MFP. Referring to FIG. 2, inside the MFP 100, a main conveyance path 41 indicated by a thick dotted line is formed so as to basically extend in the vertical direction. The main conveyance path 41 is a path for guiding the paper conveyed from the paper feeding unit 150 through the image forming unit 140 to the paper discharge tray 159. In the main conveyance path 41 of this example, the lower end 43 on the opposite side of the upper end 13 located above the image forming unit 140 constitutes an inlet for receiving the paper from the paper feeding unit 150. Further, the upper end 13 of the main conveyance path 41 constitutes an outlet for discharging the paper after image formation to the paper discharge tray 159. A paper discharge roller 15 is provided at the upper end 13 of the main conveyance path 41. The lower end 43 of the main conveyance path 41 is connected to a plurality of sub-conveyance paths SP1, SP2, SP3 of the paper feeding unit 150 described later.

[0013] The paper feeding unit 150 includes three paper feeding trays 151, 152, 153 and a manual feed tray 154. The three paper feeding trays 151, 152, 153 are stacked and arranged so as to be aligned from above to below in this order. The manual feed tray 154 is provided on the side door 11A of the main body frame 11 of the MFP 100 and is located below the image forming unit 140. As shown by the thick dashed line in Fig. 2, in the paper feeding unit 150, a sub-conveying path SP1 extending from the paper feeding tray 151 located at the upper stage among the three paper feeding trays 151, 152, 153 to the lower end portion 43 of the main conveying path 41 is formed. Also, a sub-conveying path SP2 extending from the manual feed tray 154 to the lower end portion 43 of the main conveying path 41 is formed. Further, two sub-conveying paths 152a, 153a extending from the paper feeding trays 152, 153 located at the middle and lower stages among the three paper feeding trays 151, 152, 153 to the lower end portion 43 of the main conveying path 41 are formed. A portion of a predetermined length from the lower end portion 43 of the main conveying path 41 of each of the two sub-conveying paths 152a, 153a is a sub-conveying path SP3 shared by the two sub-conveying paths 152a, 153a.

[0014] Corresponding to the paper feeding tray 151, a pickup roller 151p and a paper feeding roller 151r are provided. The paper feeding roller 151r is provided on the sub-conveying path SP1. Corresponding to the paper feeding tray 152, a pickup roller 152p and a paper feeding roller 152r are provided. The paper feeding roller 152r is provided on the sub-conveying path 152a. Corresponding to the paper feeding tray 153, a pickup roller 153p and a paper feeding roller 153r are provided. The paper feeding roller 153r is provided on the sub-conveying path 153a. Corresponding to the manual feed tray 154, a manual paper feeding unit 170 is provided. The manual paper feeding unit 170 is provided on the sub-conveying path SP2.

[0015] Since the operations of taking out and conveying sheets from each of the paper feed trays 151, 152, and 153 are the same, the paper feed tray 151 will be described as an example here. One or more sheets are stored in the paper feed tray 151 in a stacked state. The paper feed tray 151 has a lift-up mechanism that pushes up one or more sheets stored therein upward. The pickup roller 151p is biased downward by an elastic member such as a spring. For this reason, the pickup roller 151p abuts on the uppermost sheet of one or more sheets stored in the paper feed tray 151 from above and presses the sheet from above. When the pickup roller 151p rotates, the uppermost sheet is sent out to the sub-conveying path SP1 by the frictional force between the sheet and the pickup roller 151p. The sheet sent out to the sub-conveying path SP1 is supplied to the main conveying path 41 by the paper feed roller 151r.

[0016] Due to the rotation of the pickup roller 151p, the uppermost sheet of one or more sheets stored in the paper feed tray 151 is sent out to the sub-conveying path SP1 by the friction with the pickup roller 151p. During this time, since the second sheet overlapping the uppermost sheet receives a frictional force from the uppermost sheet, the second sheet may be conveyed together with the uppermost sheet. To prevent this, a separating roller is arranged at a position facing the pickup roller 151p. The separating roller contacts the second sheet. The force biasing the pickup roller 151p is adjusted so that the frictional force between the pickup roller 151p and the uppermost sheet and the frictional force between the separating roller and the second sheet are greater than the frictional force between the uppermost sheet and the second sheet.

[0017] One or more sheets are placed on the manual feed tray 154 in a stacked state. The manual paper feed unit 170 sends out the sheets on the manual feed tray 154 to the sub-conveying path SP2 in order from the uppermost sheet. The sheet sent out to the sub-conveying path SP2 is supplied to the main conveying path 41 by the paper feed roller 161.

[0018] In the MFP100, when forming an image, a tray in which the paper to be image-formed is stored is selected as the target tray from among the three paper feed trays 151, 152, 153 and the manual feed tray 154. The pickup roller and the paper feed roller corresponding to the tray selected as the target tray among the three paper feed trays 151, 152, 153 and the manual feed tray 154 operate. Thereby, the paper is supplied from the tray selected as the target tray to the main conveyance path 41 through any one of the sub-conveyance paths SP1, SP2, SP3.

[0019] The image forming unit 140 includes image forming units 21Y, 21M, 21C, and 21K for yellow, magenta, cyan, and black respectively. When at least one of the image forming units 21Y, 21M, 21C, 21K is driven, an image is formed on the paper. When all of the image forming units 21Y, 21M, 21C, 21K are driven, a full-color image is formed. Print data for yellow, magenta, cyan, and black are input to the image forming units 21Y, 21M, 21C, 21K respectively. Since the image forming units 21Y, 21M, 21C, 21K only differ in the color of the toner they handle, here, the image forming unit 21Y for forming a yellow image will be described.

[0020] The image forming unit 21Y includes an exposure head to which yellow print data is input, a photosensitive drum, a charging charger, a developing device, and a transfer roller 23Y. The exposure head emits laser light according to the received print data (electrical signal). The emitted laser light is one-dimensionally scanned by a polygon mirror included in the exposure head to expose the photosensitive drum. The direction of one-dimensionally scanning the photosensitive drum is the main scanning direction. The photosensitive drum is charged by the charging charger and then irradiated with the laser light emitted by the exposure head. Thereby, an electrostatic latent image is formed on the photosensitive drum. Subsequently, toner is placed on the electrostatic latent image by the developing device to form a toner image. The toner image formed on the photosensitive drum is transferred onto the intermediate transfer belt 27 by the transfer roller 23Y.

[0021] On the other hand, the intermediate transfer belt 27 is suspended by the driving roller 24 and the roller 24A so as not to be slack. When the driving roller 24 rotates counterclockwise in the figure, the intermediate transfer belt 27 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 27 rotates, the roller 24A rotates counterclockwise.

[0022] Thereby, the image forming units 21Y, 21M, 21C, and 21K transfer the toner images onto the intermediate transfer belt 27 in order. The timing at which each of the image forming units 21Y, 21M, 21C, and 21K transfers the toner image onto the intermediate transfer belt 27 is adjusted by detecting a reference mark attached to the intermediate transfer belt 27. Thereby, the yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 27.

[0023] In the main conveyance path 41, a timing roller 45, a transfer roller 47, and a fixing roller 49 are arranged at intervals in this order from the lower end portion 43 to the upper end portion 13. The paper supplied from the paper feeding unit 150 to the main conveyance path 41 is sent to the timing roller 45.

[0024] The timing roller 45 adjusts the conveyance state of the paper in the main conveyance path 41 so that the paper reaches the transfer roller 47 at the timing when the toner image formed on the intermediate transfer belt 27 reaches the transfer roller 47. The paper conveyed by the timing roller 45 is pressed against the intermediate transfer belt 27 by the transfer roller 47. By charging the transfer roller 47, the yellow, magenta, cyan, and black toner images formed superimposed on the intermediate transfer belt 27 are transferred onto the paper. The charge amount of the transfer roller 47 is adjusted to a value suitable for the basis weight of the paper by controlling the voltage applied to the transfer roller 47 by the CPU.

[0025] The sheet onto which the toner image has been transferred is conveyed to the fixing roller 49 and heated by the fixing roller 49. As a result, the toner is melted and fixed onto the sheet. Thereafter, the sheet after image formation is discharged onto the paper discharge tray 159 from the upper end portion 13 of the main conveyance path 41 by the paper discharge roller 15. The temperature of the fixing roller 49 is adjusted to a value suitable for the basis weight of the sheet by being controlled by the CPU.

[0026] The paper discharge tray 159 and the manual feed tray 154 are arranged with the main conveyance path 41 therebetween. The paper discharge tray 159 and the manual feed tray 154 are respectively arranged on two opposite side surfaces of the main body of the MFP 100. Here, the manual feed tray 154 is arranged on the left side surface, and the paper discharge tray 159 is arranged on the right side surface.

[0027] FIG. 3 is a perspective view of the door of the main body frame as viewed from the inside. FIG. 4 is a partially enlarged view of FIG. 3. Referring to FIGS. 3 and 4, the manual paper feed unit 170 is arranged at a position corresponding to the paper guide pair 155 inside the side door 11A of the main body frame 11. Below the manual paper feed unit 170, the paper guide pair 155 is arranged. The paper guide pair 155 forms a part of each of the sub-conveyance path SP2 and the sub-conveyance path SP3. The surface forming the sub-conveyance path SP3 of the paper guide pair 155 is shown in FIGS. 3 and 4.

[0028] FIG. 5 is a perspective view of the manual paper feed unit. FIG. 6 is a front view of the manual paper feed unit. FIG. 7 is a first cross-sectional view of the manual paper feed unit. FIG. 5 is a perspective view of the manual paper feed unit 170 as viewed from the inside of the side door 11A of the main body frame 11. FIG. 6 is a front view of the manual paper feed unit 170 as viewed from the outside of the side door 11A of the main body frame 11. Referring to FIGS. 5 to 7, the manual paper feed unit 170 includes a paper feed roller 161, a front guide member 163, a guide roller 165, and a pair of first holding portions 171A and second holding portions 171B.

[0029] The paper feed roller 161 is formed of an elastic member such as rubber and has a cylindrical shape. A pair of first holding portions 171A and second holding portions 171B are arranged at both ends of the paper feed roller 161. The paper feed roller 161 has a paper feed roller shaft 162 which is its axis of rotational symmetry. The paper feed roller shaft 162 is supported by the pair of first holding portions 171A and second holding portions 171B. Each of the pair of first holding portions 171A and second holding portions 171B has its upper end fixed to a fixing member 11B of the main body frame 11 by a screw 201.

[0030] The paper feed roller 161 is rotatable around the paper feed roller shaft 162. A rotational force of a motor (not shown) is transmitted to the paper feed roller shaft 162. For this reason, the rotational force of the motor is transmitted through the paper feed roller shaft 162, and the paper feed roller 161 rotates around the paper feed roller shaft 162. The direction in which the paper feed roller 161 rotates is clockwise as indicated by the arrow in FIG. 7.

[0031] The front guiding member 163 is fixed to the main body frame 11. The front guiding member 163 is plate-shaped and is formed of resin or metal. The front guiding member 163 is attached and fixed to a plate-shaped portion extending in the vertical direction of the main body frame 11 by, for example, double-sided tape. The front guiding member 163 is disposed below the paper feed roller 161 at a position where it contacts the paper feed roller 161.

[0032] The guiding roller 165 has a cylindrical shape. The guiding roller 165 has a guiding roller shaft 166 which coincides with its axis of rotational symmetry. The guiding roller shaft 166 has both ends supported by the main body frame 11. The guiding roller 165 is disposed below the paper feed roller 161 at a position where it does not contact the paper feed roller 161. The guiding roller 165 is rotatable around the guiding roller shaft 166.

[0033] The position where the paper feed roller 161 contacts the front guiding member 163 and the guiding roller 165 is upstream of the guiding roller 165 with respect to the paper feed roller shaft 162 in the rotational direction of the paper feed roller shaft 162.

[0034] The manual feed tray 154 is plate-shaped and has a placement surface on which a bundle of one or more sheets of paper is placed. On the placement surface of the manual feed tray 154, a positioning plate pair 157 and a biasing plate 156 are attached. The positioning plate pair 157 has a positioning surface that is perpendicular to the placement surface and parallel to the paper conveyance direction. The paper guide pair 155 is arranged on the manual feed tray 154 with the positioning surfaces facing each other. The paper guide pair 155 is movable in one direction and is movable in a direction in which the respective positioning surfaces approach each other and a direction in which they move away from each other. The user can align the width direction of the bundle of one or more sheets of paper placed on the manual feed tray 154 by moving the positioning plate pair 157. The width direction is a direction perpendicular to the paper conveyance direction.

[0035] The biasing plate 156 is a plate-shaped member and has a rotation axis that is parallel to the placement surface of the manual feed tray 154 and perpendicular to the paper conveyance direction. The biasing plate 156 is pivotally supported by the manual feed tray 154 about the rotation axis and is attached to the manual feed tray 154 so as to be rotatable about the rotation axis. An elastic member that biases the biasing plate 156 upward is provided between the biasing plate 156 and the manual feed tray 154. For this reason, when the biasing plate 156 is biased upward by the elastic member, the one or more sheets of paper placed on the manual feed tray 154 move upward. The first cross-sectional view shown in FIG. 7 shows a state in which the biasing plate 156 of the manual feed tray 154 is pushed downward.

[0036] FIG. 8 is a second cross-sectional view of the manual paper feed unit. The second cross-sectional view shown in FIG. 8 shows a state after the biasing plate 156 of the manual feed tray 154 has moved upward. Referring to FIG. 8, a plurality of sheets of paper P are moved upward by the biasing plate 156, and the uppermost sheet of paper P abuts against the paper feed roller 161. The paper conveyance direction is the circumferential direction of the paper feed roller 161 at the position where the paper P and the paper feed roller 161 are in contact. In other words, the paper conveyance direction is perpendicular to the paper feed roller axis 162 of the paper feed roller 161 and is a direction from the outside to the inside of the side door 11A of the main body frame 11.

[0037] FIG. 9 is a perspective view of the first holding part. FIG. 10 is a top view of the first holding part. FIG. 11 is a front view of the first holding part. FIG. 12 is a side view of the first holding part. In FIG. 9, arrow A indicates the direction of viewing the first holding part 171A from above, hereinafter referred to as the A direction. Arrow B and arrow C intersect perpendicularly to arrow A and are perpendicular to each other. Hereinafter, the direction indicated by arrow B is referred to as the B direction, and the direction indicated by arrow C is referred to as the C direction. FIG. 10 is a view of the first holding part 171A viewed from the A direction. FIG. 11 is a view of the first holding part 171A viewed from the B direction. FIG. 12 is a view of the first holding part 171A viewed from the C direction.

[0038] Referring to FIGS. 9 to 12, the first holding part 171A has a fixing part 172 and a support part 173. Each of the fixing part 172 and the support part 173 has a flat plate shape and intersects at a right angle. The first holding part 171A is manufactured by bending a metal flat plate at an angle of 90°.

[0039] The fixing part 172 is formed with a mounting hole 174. When the first holding part 171A is fixed to the main body frame 11, the screw 201 passes through the mounting hole 174. The support part 173 is formed with a bearing part 175. The bearing part 175 pivotally supports the paper feed roller shaft 162 of the paper feed roller 161.

[0040] FIG. 13 is a perspective view of the front guiding member. FIG. 14 is a side view of the front guiding member. Referring to FIGS. 13 and 14, the front guiding member 163 has a shape in which a flat plate is bent along a line at a predetermined distance from above. The upper end portion of the front guiding member 163 at a predetermined distance from the upper end is inclined toward the paper conveyance direction side. The pressing end portion 164, which is the upper end of the front guiding member 163, abuts against the paper feed roller 161.

[0041] Referring to FIG. 6, the first holding portion 171A has its fixing portion 172 fixed to the upper surface of the fixing member 11B of the main body frame 11, and the second holding portion 171B is fixed to the lower surface of the fixing member 11B. Therefore, the length from the fixing portion 172 to the bearing portion 175 of the second holding portion 171B is shorter than the length from the fixing portion 172 to the bearing portion 175 of the first holding portion 171A by the total length of the thickness of the fixing member 11B and the thickness of the fixing portion 172. Other configurations of the second holding portion 171B are the same as those of the first holding portion 171A. Therefore, a detailed description of the second holding portion 171B will not be repeated.

[0042] As shown in FIGS. 5 and 6, an adjusting member 181 is disposed between the fixing portion 172 of the first holding portion 171A and the fixing member 11B of the main body frame 11. Therefore, the height position of the bearing portion 175 of the first holding portion 171A is higher than the height position of the bearing portion 175 of the second holding portion 171B by the thickness of the adjusting member 181. For this reason, the paper feed roller shaft 162 of the paper feed roller 161 is inclined with respect to the guiding roller shaft 166 of the guiding roller 165 and the pressing end portion 164 of the front guiding member 163, respectively.

[0043] The end of the paper feed roller shaft 162 of the paper feed roller 161 on the side of the first holding portion 171A is above the end on the side of the second holding portion 171B. For this reason, the distance between the paper feed roller shaft 162 of the paper feed roller 161 and the pressing end portion 164 of the front guide member 163 gradually increases from the end on the side of the second holding portion 171B of the paper feed roller shaft 162 toward the end on the side of the first holding portion 171A. The distance between the paper feed roller shaft 162 of the paper feed roller 161 and the pressing end portion 164 of the front guide member 163 is minimum at the end on the side of the second holding portion 171B of the paper feed roller shaft 162 and maximum at the end on the side of the first holding portion 171A. Similarly, the distance between the paper feed roller shaft 162 of the paper feed roller 161 and the guide roller shaft 166 of the guide roller 165 gradually increases from the end on the side of the second holding portion 171B of the paper feed roller shaft 162 toward the end on the side of the first holding portion 171A. The distance between the paper feed roller shaft 162 of the paper feed roller 161 and the guide roller shaft 166 of the guide roller 165 is minimum at the end on the side of the second holding portion 171B of the paper feed roller shaft 162 and maximum at the end on the side of the first holding portion 171A.

[0044] FIG. 15 is a perspective view of the adjustment member as viewed obliquely from above. FIG. 16 is a top view of the adjustment member. FIG. 17 is a perspective view of the adjustment member as viewed obliquely from below. FIG. 18 is a bottom view of the adjustment member. FIG. 19 is a cross-sectional view taken along line A-A of FIG. 16. FIG. 20 is a cross-sectional view taken along line B-B of FIG. 16. Referring to FIGS. 15 to 20, the adjustment member 181 has a flat cylindrical shape. The adjustment member 181 has a bottom surface 185 and an upper surface facing each other. The upper surface includes a first upper surface 186A, a second upper surface 186B, a third upper surface 186C, and a fourth upper surface 186D having different heights from the bottom surface 185. The adjustment member 181 has a first selection portion 181A having the first upper surface 186A, a second selection portion 181B having the second upper surface 186B, a third selection portion 181C having the third upper surface 186C, and a fourth selection portion 181D having the fourth upper surface 186D.

[0045] As shown in FIG. 16, the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D are arranged in this order and side by side in the circumferential direction around the axis of the adjustment member 181. As shown in FIGS. 19 and 20, the first upper surface 186A, the second upper surface 186B, the third upper surface 186C, and the fourth upper surface 186D are in this order shorter in height from the bottom surface 185. The height of the first upper surface 186A from the bottom surface 185 is the shortest, and the height of the fourth upper surface 186D from the bottom surface 185 is the longest. Further, the adjustment member 181 is formed with a groove portion 182 extending along the circumferential direction around its axis. The width of the groove portion 182 is constant. The width of the groove portion 182 is the radial length around the axis of the adjustment member 181.

[0046] As shown in FIGS. 17, 18 to 20, the adjustment member 181 has a convex portion 184 extending downward from the center of its bottom surface 185. The convex portion 184 has a cylindrical shape, and its axis coincides with the axis of the adjustment member 181.

[0047] Referring to FIG. 6, the adjustment member 181 is disposed between the fixing member 11B and the fixing portion 172 of the first holding portion 171A. Any one of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D of the adjustment member 181 is disposed between the fixing member 11B and the fixing portion 172 of the first holding portion 171A. The convex portion 184 of the adjustment member 181 engages with a circular hole formed in the fixing member 11B. Thereby, the adjustment member 181 can rotate about the convex portion 184.

[0048] The screw 201 is screwed into a female screw formed in the fixing member 11B through a mounting hole 174 formed in the fixing portion 172 of the first holding portion 171A and the groove portion 182 formed in the adjustment member 181. When the length of the portion of the screw 201 where the male screw is formed and which does not engage with the fixing member 11B is equal to or less than the thicknesses of the adjustment member 181 and the fixing portion 172, the adjustment member 181 and the first holding portion 171A are fixed to the fixing member 11B.

[0049] When the user loosens the screw 201, the length of the portion of the screw part of the screw 201 that does not engage with the fixing member 11B becomes longer than the thicknesses of the adjustment member 181 and the fixing part 172. In a state where the screw 201 is loosened, the adjustment member 181 can be rotated. In this case, it is preferable that at least a part of the screw 201 is engaged with the female screw formed in the hole of the fixing member 11B. The user can rotate the adjustment member 181 without removing the screw 201 from the fixing member 11B. The user can position any one of the first selection part 181A, the second selection part 181B, the third selection part 181C, and the fourth selection part 181D of the adjustment member 181 between the fixing part 172 of the first holding part 171A and the fixing member 11B. Hereinafter, one of the first selection part 181A, the second selection part 181B, the third selection part 181C, and the fourth selection part 181D that is located between the fixing part 172 of the first holding part 171A and the fixing member 11B is referred to as the fixing part.

[0050] The height direction position of the bearing part 175 of the first holding part 171A varies depending on the fixing part of the adjustment member 181. When the fixing part is the first selection part 181A, the height direction position is the lowest, and when the fixing part is the fourth selection part 181D, the height direction position is the highest. The height direction position of the bearing part 175 of the second holding part 171B is constant. For this reason, the paper feed roller shaft 162 is inclined with respect to the pressing end part 164 of the front flapping member 163 and the flapping roller shaft 166 of the flapping roller 165. Note that a universal joint may be provided between both ends of the paper feed roller shaft 162 and the bearing part 175 of the first holding part 171A and the bearing part 175 of the second holding part 171B. Thereby, the rotational force of the motor can be accurately transmitted with respect to the inclination of the paper feed roller shaft 162.

[0051] The pressing end portion 164 of the front guiding member 163 and the guiding roller shaft 166 of the guiding roller 165 are each fixed in their relative positions with respect to the main body frame 11. Here, the distance between the paper feed roller shaft 162 and the pressing end portion 164 of the front guiding member 163 or the distance between the paper feed roller shaft 162 and the guiding roller shaft 166 of the guiding roller 165 is referred to as the inclined distance. In the present embodiment, the inclined distance at the end portion on the second holding portion 171B side of the paper feed roller 161 is the shortest, and the inclined distance at the end portion on the first holding portion 171A side of the paper feed roller 161 is the longest.

[0052] Here, with reference to FIG. 8, the conveyance of the paper by the paper feed roller 161 will be described. A plurality of sheets of paper P placed on the manual feed tray 154 are pushed up by the biasing plate 156, and the uppermost sheet of paper P among the plurality of sheets of paper P is pressed against the paper feed roller 161. The paper conveyance direction is the circumferential direction of the paper feed roller 161 at the position where the paper and the paper feed roller 161 are in contact. In other words, the paper conveyance direction is perpendicular to the paper feed roller shaft 162 of the paper feed roller 161 and is a direction from the outside to the inside of the side door 11A of the main body frame 11.

[0053] In this state, when the paper feed roller 161 rotates, a frictional force is generated between the paper feed roller 161 and the uppermost sheet of paper P. Also, a frictional force is generated between the uppermost sheet of paper P and the second sheet of paper P stacked thereunder. Further, a frictional force is generated between two sheets of paper in contact with each other among the third and subsequent sheets of paper stacked below the second sheet of paper. The material of the paper feed roller 161 and the elastic force applied to the biasing plate 156 are adjusted so that the frictional force between the paper feed roller 161 and the uppermost sheet of paper P becomes the highest. For this reason, when the paper feed roller 161 rotates, the uppermost sheet of paper P is conveyed. On the other hand, the frictional force generated between two sheets of paper in contact with each other may change due to changes in the environment such as temperature or humidity. For this reason, when the paper feed roller 161 rotates, the second and subsequent sheets of paper P may be conveyed together with the uppermost sheet of paper P.

[0054] In this case, two or more sheets of paper abut against the front separating member 163. The two or more sheets of paper receive a force in the direction opposite to the conveyance direction from the front separating member 163. Since the frictional force between the paper feed roller 161 and the uppermost sheet of paper P is the highest, the uppermost sheet of paper P is conveyed against the force received from the front separating member 163. For the second and subsequent sheets of paper P, if the frictional force received from the other sheet is smaller than the force received from the front separating member 163, they stop in contact with the front separating member 163 without being conveyed.

[0055] As shown in FIG. 6, the inclined distance at the end of the paper feed roller 161 on the side of the first holding portion 171A is the longest, and the inclined distance at the end of the paper feed roller 161 on the side of the second holding portion 171B is the shortest. For this reason, the frictional force between the paper feed roller 161 and the uppermost sheet of paper P at the end of the paper feed roller 161 on the side of the second holding portion 171B is the largest. Also, the frictional force between the paper feed roller 161 and the uppermost sheet of paper P at the end of the paper feed roller 161 on the side of the first holding portion 171A is the smallest.

[0056] The frictional force between the paper feed roller 161 and the uppermost sheet of paper P at the end of the paper feed roller 161 on the side of the second holding portion 171B is adjusted to be a value suitable for thin paper with a small thickness. For this reason, when the paper P is thin paper, the uppermost sheet of paper P is conveyed at the end of the paper feed roller 161 on the side of the second holding portion 171B. The probability that the second and subsequent sheets of paper abut against the front separating member 163 and stop is higher compared to other portions other than the end of the paper feed roller 161 on the side of the second holding portion 171B.

[0057] On one side, the inclination distance at the end on the first holding portion 171A side of the paper feed roller 161 is the longest. The frictional force between the paper feed roller 161 and the uppermost sheet P at the end on the first holding portion 171A side of the paper feed roller 161 is adjusted to a value suitable for thick paper. Specifically, any one of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D of the adjustment member 181 is selected. When the sheet P is thick cardboard, the force received by the second sheet P from the front guide member 163 is adjusted to be greater than the frictional force between the uppermost sheet P and the paper feed roller 161. For this reason, at the end on the first holding portion 171A side of the paper feed roller 161, the probability that the uppermost sheet P is conveyed and the second and subsequent sheets P abut against the front guide member 163 and stop is greater than that at other portions other than the end on the first holding portion 171A side of the paper feed roller 161.

[0058] As described above, the MFP 100 in the present embodiment pivotally supports the paper feed roller shaft 162 at both ends of the paper feed roller 161, and includes a pair of first holding portions 171A and second holding portions 171B attached to the fixing member 11B of the main body frame 11, a front guide member 163 attached to the main body frame 11 facing the paper feed roller 161, and an adjustment member 181. The adjustment member 181 has a first selection portion 181A, a second selection portion 181B, a third selection portion 181C, and a fourth selection portion 181D each having a first upper surface 186A, a second upper surface 186B, a third upper surface 186C, and a fourth upper surface 186D with different heights from a common bottom surface, and any one of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D is disposed between the fixing member 11B of the main body frame 11 and the first holding portion 171A.

[0059] One of the first selection part 181A, the second selection part 181B, the third selection part 181C, and the fourth selection part 181D is selected as a fixed part to be arranged between the first holding part 171A and the fixing member 11B. The distance between the first holding part 171A and the fixing member 11B varies, and the relative position between the pre-deflecting member 163 facing the paper feed roller 161 and the paper feed roller 161 varies. The inclination distance is different at a plurality of positions in the axial direction of the paper feed roller shaft 162. Therefore, the operator can adjust the relative position between the paper feed roller 161 and the pre-deflecting member 163 by selecting one of the predetermined first selection part 181A, second selection part 181B, third selection part 181C, and fourth selection part 181D. As a result, it is possible to facilitate the operation of adjusting to positions suitable for a plurality of types of papers with different thicknesses.

[0060] Further, including the first holding part 171A and the second holding part 171B respectively provided at both ends of the paper feed roller 161, the adjustment member 181 is arranged between the fixing member 11B and the first holding part 171A and is not arranged between the second holding part 171B and the fixing member 11B. The distance between the pre-deflecting member 163 and the paper feed roller shaft 162 is different at a plurality of positions different in the axial direction of the paper feed roller shaft 162. When the fixed part arranged between the first holding part 171A and the fixing member 11B is changed, the distance between the first holding part 171A and the fixing member 11B varies without the distance between the second holding part 171B and the fixing member 11B varying. The relative position between the pre-deflecting member 163 and the paper feed roller 161 varies. The inclination distance is different at a plurality of positions in the axial direction of the paper feed roller shaft 162. The distance between the pre-deflecting member 163 and the paper feed roller shaft 162 can be provided in the axial direction of the paper feed roller shaft 162 at positions adapted to thin paper and positions adapted to thick paper. Therefore, it becomes possible to appropriately deflect a plurality of types of papers P with different thicknesses.

[0061] In addition, the distance between the pre-guide member 163 and the paper feed roller shaft 162 varies at a plurality of different positions in the direction of the paper feed roller shaft 162. The distance between the pre-guide member 163 and the paper feed roller shaft 162 can be provided at positions adjusted for thin paper and positions adjusted for thick paper in the axial direction of the paper feed roller shaft 162. Therefore, it becomes possible to appropriately guide a plurality of types of paper P with different thicknesses.

[0062] In addition, the adjustment member 181 has a convex portion 184 protruding from the bottom surface 185, and the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D are arranged side by side in the circumferential direction centered on the convex portion 184. Therefore, if the operator rotates the adjustment member 181 around the convex portion 184, it can be easily changed to one of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D. Therefore, there is no need to prepare a member different from the adjustment member 181.

[0063] In addition, the adjustment member 181 is formed with groove portions 182 penetrating from the first upper surface 186A, the second upper surface 186B, the third upper surface 186C, and the fourth upper surface 186D respectively to the bottom surface along an arc centered on the convex portion 184. The screw 201 passes through the groove portion 182 and fixes the first holding portion 171A to the fixing member 11B of the main body frame 11. Therefore, with the screw 201 passing through the groove portion 182, the adjustment member 181 can be rotated around the convex portion 184. Therefore, the operation of changing the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D is easy.

[0064] Each of the first holding portion 171A and the second holding portion 171B has a fixing portion 172 attached to the fixing member 11B of the main body frame 11 and a support portion 173 that pivotally supports the paper feed roller shaft 162 of the paper feed roller 161. The support portion 173 is located above the portion where the pre-guide member 163 contacts the paper feed roller 161 and below the fixing portion 172. Therefore, the paper P can pass between the paper feed roller 161 and the pre-guide member 163. Therefore, the configuration of the apparatus can be simplified.

[0065] Further, the MFP 100 further includes a separating roller 165 attached to the main body frame 11 so as to face the paper feed roller 161 on the downstream side of the front separating member 163 in the rotation direction of the paper feed roller 161. Since the separating roller 165 is provided on the downstream side of the front separating member 163, a plurality of sheets P that are double-fed between the paper feed roller 161 and the front separating member 163 can be separated and only one sheet P can pass through.

[0066] The MFP 100 includes a biasing plate 156 that is provided below the paper feed roller 161 and biased upward. The position where the sheet P placed on the biasing plate 156 contacts the paper feed roller 161 is upstream of the position where the front separating member 163 contacts the paper feed roller 161 in the rotation direction of the paper feed roller 161. When a plurality of sheets P are conveyed overlapping each other by the paper feed roller 161, a force opposite to the conveying direction is applied to the sheet P that does not contact the paper feed roller 161 by the front separating member 163. Therefore, a plurality of sheets P can be separated and one sheet P can be conveyed.

[0067] <Modification Example> (1) In the above-described embodiment, the adjustment member 181 is disposed between the first holding portion 171A and the fixing member 11B. The adjustment member 181 may be disposed between the second holding portion 171B and the fixing member 11B. In this case, the adjustment member 181 may also be disposed between the first holding portion 171A and the fixing member 11B. The distance between the paper feed roller shaft 162 and the front separating member 163 at the end of the paper feed roller 161 on the second holding portion 171B side can be adjusted. Therefore, the distance between the paper feed roller shaft 162 and the front separating member 163 at either one of the ends of the paper feed roller 161 on the first holding portion 171A side or the second holding portion 171B side is adjusted according to thin paper. The distance between the paper feed roller shaft 162 and the front separating member 163 at the other end of the paper feed roller 161 on the first holding portion 171A side or the second holding portion 171B side is adjusted according to thick paper.

[0068] (2) An adjustment member 181 is disposed between the second holding portion 171B and the fixing member 11B, and the adjustment member 181 may not be disposed between the first holding portion 171A and the fixing member 11B. In this case, the distance between the paper feed roller shaft 162 and the pre-guide member 163 at the end of the paper feed roller 161 on the side of the first holding portion 171A is adjusted according to thin paper. Also, the distance between the paper feed roller shaft 162 and the pre-guide member 163 at the end of the paper feed roller 161 on the side of the second holding portion 171B is adjusted according to thick paper.

[0069] (3) Although an example in which the image forming unit 140 forms an image by an electrophotographic method using toner has been described, the present invention is not limited to this. The image forming unit 140 may form an image by an inkjet method using ink.

[0070] (4) In the above-described embodiment, an example in which the manual paper feed unit 170 is set to be suitable for a plurality of types of papers having different thicknesses by selecting one of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D has been shown. However, even for papers of the same thickness, the frictional force between the paper feed roller 161 and the paper may vary due to environmental changes or aging deterioration of the paper feed roller 161. In order to cope with this variation, the manual paper feed unit 170 may be adjusted by selecting one of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D.

[0071] (5) Although the case where the adjustment member 181 includes four of the first selection portion 181A, the second selection portion 181B, the third selection portion 181C, and the fourth selection portion 181D has been described as an example, a plurality of surfaces having different distances from the bottom surface 185 may be two or more.

[0072] <Summary of the Embodiment> (Item 1) A paper feed roller that conveys the recording medium by rotating around a rotation axis, A pair of holding portions that support the rotation axis and are attached to the main body frame, A guide member attached to the main body frame facing the paper feed roller, An image forming apparatus including a plurality of selection portions each having a plurality of upper surfaces with different heights from a common bottom surface, and one of the plurality of selection portions being disposed between the main body frame and the holding portion.

[0073] According to this aspect, one of the plurality of selection portions of the adjustment member is disposed between the holding portion that pivotally supports the rotation axis of the paper feed roller and the main body frame. Therefore, when the selection portion disposed between the holding portion and the main body frame is changed, the distance between the holding portion and the main body frame fluctuates, and the relative position between the guide member facing the paper feed roller and the paper feed roller fluctuates. The amount of fluctuation is different at a plurality of positions in the rotation axis direction. For this reason, an operator can adjust the relative position between the paper feed roller and the guide member by selecting one from a plurality of predetermined selection portions. As a result, it is possible to provide an image forming apparatus that facilitates the operation of adjusting to a position suitable for a plurality of types of recording media having different thicknesses.

[0074] (Item 2) The holding portion includes a first holding portion and a second holding portion respectively provided at both ends of the paper feed roller, The adjustment member is disposed between the main body frame and the first holding portion, The distance between the guide member and the rotation axis is different at a plurality of positions in the direction of the rotation axis. The image forming apparatus according to Item 1.

[0075] According to this aspect, when the selection portion disposed between the first holding portion and the main body frame is changed, the distance between the first holding portion and the main body frame fluctuates without the distance between the second holding portion and the main body frame fluctuating, and the relative position between the guide member and the paper feed roller fluctuates. The amount of fluctuation is different at a plurality of positions in the rotation axis direction. The distance between the guide member and the rotation axis can be provided in the direction of the rotation axis at a position suitable for a thin recording medium and a position suitable for a thick recording medium. For this reason, it becomes possible to appropriately guide a plurality of types of recording media having different thicknesses.

[0076] (Item 3) The adjustment member has a convex portion protruding from the bottom surface, The plurality of selection portions are arranged side by side in the circumferential direction centered on the convex portion, and the image forming apparatus according to claim 1.

[0077] According to this aspect, the plurality of selection portions are arranged side by side in the circumferential direction centered on the convex portion protruding from the bottom surface. Therefore, if the operator rotates the adjustment member around the convex portion, the selection portion located between the holding portion and the main body frame among the plurality of selection portions can be changed. Therefore, it is not necessary to prepare a member different from the adjustment member.

[0078] (Item 4) The adjustment member is formed with groove portions penetrating from each of the plurality of upper surfaces to the bottom surface along an arc centered on the convex portion, The image forming apparatus according to claim 3, further comprising a fixing member that passes through the groove portion and fixes the holding portion to the main body frame.

[0079] According to this aspect, the fixing member passes through the groove portions penetrating from each of the plurality of upper surfaces to the bottom surface along an arc centered on the convex portion. Therefore, with the fixing member passing through the groove portion, the adjustment member can be rotated around the convex portion. Therefore, the operation of changing the selection portion located between the holding portion and the main body frame among the plurality of selection portions is easy.

[0080] (Item 5) The holding portion has a mounting portion attached to the main body frame and a shaft support portion that pivotally supports the rotation shaft of the paper feed roller, The shaft support portion is located above the portion where the guiding member contacts the paper feed roller and below the mounting portion, and the image forming apparatus according to any one of claims 1 to 4.

[0081] According to this aspect, since the shaft support portion is located above the portion where the guiding member contacts the paper feed roller and below the mounting portion, the recording medium can pass between the paper feed roller and the guiding member. Therefore, the configuration of the apparatus can be simplified.

[0082] (Item 6) The image forming apparatus according to any one of Items 1 to 4, further comprising a separating roller attached to the main body frame so as to face the paper feed roller on the downstream side of the separating member in the rotation direction of the paper feed roller.

[0083] According to this aspect, since the separating roller is provided on the downstream side of the separating member, it is possible to separate a plurality of recording media that have been double-fed between the paper feed roller and the separating member and allow one recording media to pass through.

[0084] (Item 7) Further comprising a biasing plate provided below the paper feed roller and biased upward, The position where the recording media placed on the biasing plate contacts the paper feed roller is upstream of the position where the separating member contacts the paper feed roller in the rotation direction of the paper feed roller. The image forming apparatus according to any one of Items 1 to 4.

[0085] According to this aspect, the recording media placed on the biasing plate is conveyed by the paper feed roller and contacts the separating member. Therefore, when a plurality of recording media are conveyed overlapping each other by the paper feed roller, a force opposite to the conveying direction is applied to the recording media that do not contact the paper feed roller by the separating member. Therefore, it is possible to separate a plurality of recording media and convey one recording media.

[0086] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the scope of the claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of the claims are included.

Explanation of Reference Numerals

[0087] 100 MFP, 110 operation panel, 120 automatic document feeder, 130 document reading unit, 140 image forming unit, 150 paper feeding unit, 11 main body frame, 11A side door, 11B fixing member, 21C, 21M, 21Y, 21K image forming units, 27 intermediate transfer belt, 41 main conveyance path, 45 timing roller, 47 transfer roller, 49 fixing roller, 151 - 153 paper feed trays, 154 manual feed tray, 155 paper guide pair, 156 biasing plate, 157 positioning plate pair, 159 paper discharge tray, 161 paper feed roller, 162 paper feed roller shaft, 163 member, 164 pressing end portion, 165 roller, 166 roller shaft, 170 manual paper feeding unit, 171A first holding portion, 171B second holding portion, 172 fixing portion, 173 support portion, 174 mounting hole, 175 bearing portion, 181 adjusting member, 181A first selection portion, 181B second selection portion, 181C third selection portion, 181D fourth selection portion, 182 groove portion, 184 convex portion, 185 bottom surface, 186A first upper surface, 186B second upper surface, 186C third upper surface, 186D fourth upper surface, 201 screw, P paper, SP1 sub - conveyance path, SP2 sub - conveyance path, SP3 sub - conveyance path.

Claims

1. A paper feed roller that rotates around a rotation axis, a holding part that supports the rotation axis and is attached to a main body frame, a guide member attached to the main body frame facing the paper feed roller, an image forming apparatus comprising: a plurality of selection parts each having a plurality of upper surfaces with different heights from a common bottom surface, and an adjustment member in which any one of the plurality of selection parts is disposed between the main body frame and the holding part.

2. The holding part includes a first holding part and a second holding part respectively provided at both ends of the paper feed roller, the adjustment member is disposed between the main body frame and the first holding part, The image forming apparatus according to claim 1, wherein a distance between the guide member and the rotation axis is different at a plurality of positions different in the direction of the rotation axis.

3. The adjustment member has a convex part protruding from the bottom surface, The image forming apparatus according to claim 1, wherein the plurality of selection parts are arranged side by side in a circumferential direction centered on the convex part.

4. The adjustment member is formed with groove parts penetrating from each of the plurality of upper surfaces to the bottom surface along an arc centered on the convex part, The image forming apparatus according to claim 3, further comprising a fixing member that passes through the groove part and fixes the holding part to the main body frame.

5. The holding part has a mounting part attached to the main body frame and a shaft support part that supports the rotation axis of the paper feed roller, The image forming apparatus according to any one of claims 1 to 4, wherein the shaft support part is located above a portion where the guide member abuts on the paper feed roller and below the mounting part.

6. The image forming apparatus according to any one of claims 1 to 4, further comprising a guide roller attached to the main body frame facing the paper feed roller on the downstream side of the guide member in the rotation direction of the paper feed roller.

7. The image forming apparatus further comprises a biasing plate provided below the paper feed roller and biased upward, The image forming apparatus according to any one of claims 1 to 4, wherein a position where a recording medium placed on the biasing plate contacts the paper feed roller is upstream in the rotation direction of the paper feed roller from a position where the guide member abuts on the paper feed roller.

Images