Sheet feeding device and image forming apparatus

Abstract

To suppress the trouble of incorrectly detecting the size of sheet placed on a feed tray from occurring.SOLUTION: A sheet feeding device comprises: a relay member 47 connected to an end fence 46 via a tension spring 49 and movable in a ±X direction together with the end fence 46; a rotating member 48 connected to the relay member 47 and rotating in a predetermined rotating direction in conjunction with movement of the relay member 47 in the ±X direction; and a size detection part 50 for detecting a corresponding sheet size among multiple sheet sizes that can be placed on a feed tray 40 corresponding to a posture of the rotation member 48 in the rotation direction. The sheet feeding device also comprises a fitted part 44b and a fitting part 47c (restricting means) that, even when the end fence 46 moves within a predetermined range in the ±X direction (contacting / separating direction) with respect to a position of the corresponding sheet size detected by the size detection part 50, restrict the relay member 47 from moving in the ±X direction (contacting / separating direction).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a sheet feeding device for feeding sheets such as paper, and an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine or a printing machine equipped with the same.

Background Art

[0002] Conventionally, in a sheet feeding device installed in an image forming apparatus such as a copying machine, a printer, or a printing machine, those that detect the size of a sheet placed on a feeding tray are widely known (see, for example, Patent Document 1).

[0003] Specifically, the sheet feeding device in Patent Document 1 is provided with fence members such as side fences and end fences that regulate the position of a sheet placed on a feeding cassette. In addition, a lever (rotating member) that rotates in a predetermined rotation direction is provided in conjunction with the movement of the fence member (the movement in the direction of approaching and separating from the sheet). Then, when the fence member moves to a position where it contacts a predetermined sheet size, the posture of the lever in the rotation direction is determined, and one or more of a plurality of push switches are selectively pushed by the lever rotated to that position, so that the size of the sheet set in the paper feed tray (feeding tray) is detected.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional sheet feeding device, when the fence member is displaced, the size of the sheet placed on the feeding tray may be erroneously detected.

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to provide a sheet feeding device and an image forming apparatus in which a malfunction of erroneously detecting the size of a sheet placed on a feeding tray hardly occurs.

Means for Solving the Problems

[0006] The sheet feeding device according to the present invention includes a feeding tray on which a sheet is placed, a fence member configured to be movable in a direction of approaching and separating from an end face of the sheet placed on the feeding tray to regulate the position of the sheet, a relay member connected to the fence member via a biasing member and movable in the approaching and separating direction together with the fence member, a rotating member connected to the relay member and rotating in a predetermined rotation direction in conjunction with the movement of the relay member in the approaching and separating direction, size detection means for detecting a corresponding sheet size among a plurality of sheet sizes that can be placed on the feeding tray corresponding to the posture of the rotating member in the rotation direction, and regulation means for regulating the relay member from moving in the approaching and separating direction even when the fence member moves in the approaching and separating direction within a predetermined range with respect to the position of the corresponding sheet size detected by the detection means.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a sheet feeding device and an image forming apparatus in which a problem of erroneously detecting the size of a sheet placed on a feeding tray hardly occurs.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the redundant description thereof will be simplified or omitted as appropriate.

[0010] First, with reference to FIG. 1, the overall configuration and operation of the image forming apparatus 1 will be described. In FIG. 1, 1 is a copying machine as an image forming apparatus, 2 is an original document reading unit that optically reads the image information of the original document D, 3 is an exposure unit that irradiates the exposure light L based on the image information read by the original document reading unit 2 onto the photosensitive drum 5, 4 is an image forming unit that forms a toner image (image) on the photosensitive drum 5, and 7 is a transfer unit (image forming unit) that transfers the toner image formed on the photosensitive drum 5 to the sheet P. Also, 10 is an original document conveyance unit (automatic original document conveyance device) that conveys the set original document D to the original document reading unit 2, 12 and 13 are sheet feeding devices that feed the sheet P stored in the paper feed tray 40, and 16 is a manual sheet feeding device that feeds the sheet P set by the user by hand. Also, 17 is a registration roller pair (conveyance roller pair) that conveys the sheet P toward the transfer unit 7, 20 is a fixing device that fixes the toner image (unfixed image) carried on the sheet P, 21 is a fixing roller installed in the fixing device 20, 22 is a pressure roller installed in the fixing device 20, and 31 is a paper discharge tray on which the sheet P discharged from the apparatus main body 1 is stacked. Also, 40 is a paper feed tray installed in each of the sheet feeding devices 12 and 13, and 60 is a feeding mechanism installed in each of the sheet feeding devices 12, 13, and 16.

[0011] With reference to FIG. 1, the operation during normal image formation in the image forming apparatus main body 1 will be described. First, the original document D is conveyed (fed) from the original document table in the direction of the arrow in the figure by the conveyance roller of the original document conveyance unit 10 and passes over the original document reading unit 2. At this time, in the original document reading unit 2, the image information of the original document D passing above is optically read. Then, the optical image information read by the original document reading unit 2 is converted into an electrical signal and then transmitted to the exposure unit 3 (writing unit). Then, from the exposure unit 3, exposure light L such as laser light based on the image information of the electrical signal is emitted toward the photosensitive drum 5 of the image forming unit 4.

[0012] On the other hand, in the image forming unit 4, the photosensitive drum 5 rotates in the clockwise direction shown in FIG. 1, and through a predetermined image forming process (charging process, exposure process, developing process), an image (toner image) corresponding to the image information is formed on the photosensitive drum 5. After that, the image formed on the photosensitive drum 5 is transferred onto the sheet P conveyed by the resist roller pair 17 in the transfer unit 7 as an image forming unit.

[0013] On the other hand, the sheet P conveyed to the transfer unit 7 (image forming unit) operates as follows. First, one of the plurality of sheet feeding devices 12 and 13 of the image forming apparatus main body 1 is selected automatically or manually (for example, it is assumed that the lower sheet feeding device 13 is selected). Then, the uppermost sheet P such as paper stored in the feeding tray 40 of the sheet feeding device 13 is fed by the feeding mechanism 60 and conveyed toward the conveying path K. After that, the sheet P passes through the conveying path K provided with a plurality of conveying rollers and reaches the position of the resist roller pair 17. When the manual sheet feeding device 16 (see FIG. 17) as a sheet feeding device installed on the side of the apparatus main body 1 is selected, the sheet P placed on the feeding tray 40 (manual tray) of the sheet feeding device 16 by the user (when a plurality of sheets P are stacked, the uppermost sheet P) is fed in the -X direction toward the conveying path by the feeding mechanism 60 and reaches the position of the resist roller pair 17.

[0014] Then, the rotation of the resist roller pair 17 is started, and the sheet P after skew correction by the resist roller pair 17 is conveyed toward the transfer unit 7 (image forming unit) in synchronization with the timing for aligning with the image formed on the photosensitive drum 5.

[0015] Then, after passing through the position of the transfer unit 7, the sheet P after the transfer process reaches the fixing device 20 via the conveyance path. The sheet P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and the toner image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22 (this is the fixing process). After the fixing process in which the toner image is fixed, the sheet P is sent out from between the fixing roller 21 and the pressure roller 22 (this is the fixing nip), and then discharged from the image forming apparatus main body 1 and stacked on the paper discharge tray 31 as an output image. In this way, a series of image forming processes is completed.

[0016] Next, with reference to FIG. 2, the sheet feeding device in the present embodiment will be described. Hereinafter, among the plurality of sheet feeding devices 12 and 13 provided inside the apparatus main body 1, the lower sheet feeding device 13 will be described. However, since the upper sheet feeding device 12 has substantially the same configuration as the lower sheet feeding device 13 except for the different installation positions, the description thereof will be omitted.

[0017] Referring to FIG. 2, the sheet feeding device 13 mainly includes a feeding tray 40 formed so as to be able to stack a plurality of sheets P (sheet bundle), and a feeding mechanism 60 for feeding the sheets P stacked on the feeding tray 40. Note that in addition to the liftable bottom plate 42 (placement part), the feeding tray 40 is provided with a pair of side fences 45, an end fence 46, a rotating member 48, a relay member 47, a size detection unit 50 (size detection means), etc. The details thereof will be described later with reference to FIGS. 3 to 16.

[0018] As shown in FIG. 2, the feeding mechanism 60 includes a feed roller 63, a pickup roller 64, a separation roller 65, etc. The feed roller 63 is installed on the front end side in the feeding direction (the direction of the white arrow in Fig. 2, which is the conveying direction) with respect to the sheet P stacked on the bottom plate 42 of the feeding tray 40, contacts the upper surface of the sheet P, rotates along the feeding direction of the sheet P (counterclockwise rotation in Fig. 2), and feeds the sheet P in the feeding direction (+X direction) indicated by the dashed-dotted arrow.

[0019] The pickup roller 64 rotates counterclockwise in Fig. 2 along the traveling direction while being in contact with the surface (upper surface) of the sheet P stacked on the feeding tray 40, and conveys the sheet P toward the position of the feed roller 63. A timing belt 69 is stretched and supported on the pulley installed on the pickup roller 64 and the pulley installed on the feed roller 63. And the drive is transmitted from the feed motor to the pickup roller 64 via the gear train, the feed roller 63, and the timing belt 69, so that the pickup roller 64 is rotationally driven counterclockwise in Fig. 2.

[0020] Also, the pickup roller 64 is configured to be able to approach and separate from the sheet P (the uppermost sheet P) stacked on the feeding tray 40. That is, the pickup roller 64 is formed to be movable between a non-contact position where it does not contact the sheet P stacked on the feeding tray 40 and a contact position where it contacts the sheet P. Specifically, the pickup roller 64 is rotatably held by an arm 68. The arm 68 is rotatably held by the shaft portion of the feed roller 63. A spring that biases the pickup roller 64 to move to the non-contact position and a solenoid that moves the pickup roller 64 to the contact position against the biasing force of the spring are connected to the arm 68. And it is controlled by the control unit so that the pickup roller 64 moves to the contact position as shown in Fig. 2 when the solenoid is turned on, and the pickup roller 64 moves to the non-contact position when the solenoid is turned off. Note that the timing belt 69 is stretched and supported by the pulleys of the pickup roller 64 and the feed roller 63 even when the pickup roller 64 makes a contact / separation operation.

[0021] The separation roller 65 is installed so as to form a nip portion with the feed roller 63. Then, the separation roller 65 rotates in the forward direction (the direction of the dashed arrow in FIG. 2, which is the clockwise direction) along the feeding direction when one sheet P is pinched in the nip portion and when no sheet P is pinched in the nip portion. On the other hand, when a plurality of sheets are pinched in the nip portion, the separation roller 65 rotates in the reverse direction (the direction of the solid arrow in FIG. 2, which is the counterclockwise direction) with respect to the above-described forward direction. As a result, the uppermost sheet P among the plurality of sheets P pinched in the nip portion is fed in the feeding direction along the rotation of the feed roller 63, and the lower sheet P is conveyed in the direction opposite to the feeding direction (forward direction), thereby suppressing double feeding of the sheet P.

[0022] Here, in the sheet feeding device 13 according to the present embodiment, the bottom plate 42 moves up and down in the vertical direction according to the number of sheets P stacked on the bottom plate 42 so that the pickup roller 64 can contact the uppermost sheet P stacked on the feed tray 40. Then, after the pickup roller 64 descends to a position where it contacts the upper surface of the sheet P placed on the bottom plate 42 whose vertical position has been adjusted, the feeding operation of the sheet P is performed. An entrance guide plate is installed between the feed tray 40 and the nip portion between the feed roller 63 and the separation roller 65.

[0023] In the sheet feeding device 13 configured as described above, when no sheet P is set on the feed tray 40, this state is detected by an end detection sensor (not shown) installed at the bottom, and the pickup roller 64 is retracted to a non-contact position by the control of the solenoid by the control unit. When the sheet P is set on the feeding tray 40, the state is detected by the end detection sensor, and the pickup roller 64 is moved from the non-contact position to the contact position (the position shown in Fig. 2) by the control of the solenoid by the control unit. Then, as shown in Fig. 2, when the pickup roller 64 is in contact with the upper surface of the uppermost sheet P placed on the bottom plate 42, the counterclockwise rotation drive of the pickup roller 64 is started, and the rotation of the feed roller 63 and the separation roller 65 is started at the same timing. As a result, the uppermost sheet P in the sheet bundle placed on the feeding tray 40 by the pickup roller 64 is conveyed toward the nip portion between the feed roller 63 and the separation roller 65, and one sheet P is separated and conveyed from the nip portion toward the image forming unit. Also, when all the sheets P placed on the feeding tray 40 are fed and the feeding tray 40 is in a state where no sheet P is set, the state is detected by the end detection sensor (not shown), and the pickup roller 64 is moved back to the non-contact position by the control of the solenoid by the control unit.

[0024] Hereinafter, with reference to Figs. 3 to 16, the characteristic configuration and operation of the sheet feeding device 13 in the present embodiment will be described. As shown in Figs. 3 to 5, the feeding tray 40 in the sheet feeding device 13 is a substantially rectangular parallelepiped box-shaped member on which the sheet P is placed. Inside the feeding tray 40, a pair of side fences 45, end fences 46, a bottom plate 42 (see Figs. 1 and 2), etc. are provided. Further, a rotating member 48 (see Fig. 4(B) etc.) is provided on the lower surface of the feeding tray 40, and a size detection unit 50 (see Fig. 4(A) etc.) as size detection means is provided on the side surface thereof. Further, a relay member 47 (see Figs. 4 and 7 etc.) is provided so that a part thereof is embedded in the guide portion 44 of the feeding tray 40. In Figs. 3, 4, etc., in order to show the structure below the bottom plate 42 (see Figs. 1, 2, etc.) inside the feeding tray 40, the illustration of the bottom plate 42 is omitted.

[0025] Here, a part of the sheet feeding device 13 (the feeding tray 40) is detachably (drawably) installed with respect to the main body 1 of the image forming apparatus. Specifically, an exterior cover is installed on one of the four side portions of the feeding tray 40. A handle (not shown) is provided on the exterior cover, and the user grips this handle to insert and remove the feeding tray 40 in the ±Y direction with respect to the main body 1 of the image forming apparatus. That is, the feeding tray 40 is detached from and attached to the main body 1 of the image forming apparatus with the width direction (a direction orthogonal to the feeding direction (+X direction) in which the sheet P placed on the feeding tray 40 is fed) as the detachment and attachment direction. Then, with the feeding tray 40 pulled out in the +Y direction (width direction) with respect to the main body 1 of the image forming apparatus, a plurality of sheets P (sheet bundle) are stacked on the feeding tray 40, and then the feeding tray 40 is attached to the main body 1 of the image forming apparatus in the -Y direction.

[0026] Here, on the feeding tray 40, one end fence 46 and a pair of side fences 45 are installed so as to surround a space (a space where the bottom plate 42 is installed) on which the sheet P is placed on three sides excluding the leading end side in the feeding direction (+X direction).

[0027] Referring to FIGS. 3 and 4(A), the end fence 46 is configured to be movable in a direction (±X direction) of approaching and separating from the end face of the sheet P (or the sheet bundle) placed on the feeding tray 40, and is a fence member that regulates the position of the sheet P (the position in the ±X direction). That is, the end fence 46 as a fence member is installed so as to abut against the trailing end in the feeding direction of the sheet P, and is configured to be movable in the feeding direction in accordance with the size of the sheet P in the feeding direction. Specifically, at the bottom of the feeding tray 40, a guide portion 44 (guide portion for the end fence) is provided to movably guide the end fence 46 in the feeding direction (the direction of approaching and separating from the sheet P placed on the feeding tray 40, which is the ±X direction). The guide portion 44 extends in the feeding direction. The end fence 46 manually moves in the ±X direction along this guide portion 44 to determine the posture of the sheet P in the feeding direction (±X direction) within the feeding tray 40. As a result, the sheet P with its position in the feeding direction (±X direction) determined from the feeding tray 40 is smoothly fed.

[0028] Referring to FIGS. 3 and 4(A), the pair of side fences 45 are configured to be movable in the direction of approaching and separating from the end face of the sheet P (or sheet bundle) placed on the feeding tray 40 (which is the ±Y direction), and are fence members that regulate the position of the sheet P (the position in the ±Y direction). That is, the pair of side fences 45 are respectively installed at both widthwise ends so as to sandwich the sheet P, and are configured to be movable in the width direction (±Y direction) according to the width size of the sheet P. Specifically, at the bottom of the feeding tray 40, a guide portion 43 (guide portion for the side fence) is provided to movably guide the side fence 45 in the ±Y direction. The guide portion 43 extends in the ±Y direction. The side fence 45 manually moves in the ±Y direction along this guide portion 43 to determine the posture of the sheet P in the ±Y direction (width direction) within the feeding tray 40. As a result, the sheet P with its position in the ±Y direction (width direction) determined from the feeding tray 40 is smoothly fed. In addition, in the present embodiment, the guide portion 43 for the side fence is configured such that a pair of side fences 45 are interlocked to increase or decrease the interval in the width direction. That is, when one side fence 45 is manually moved in the +Y direction, the other side fence 45 is moved in the -Y direction in conjunction, and when one side fence 45 is manually moved in the -Y direction, the other side fence 45 is moved in the +Y direction in conjunction. Specifically, the guide portion 43 that also functions as a moving mechanism for interlocking a pair of side fences 45 includes a rack gear portion integrally formed so as to extend in the width direction orthogonally to one side fence 45, a rack gear portion integrally formed so as to extend in the width direction orthogonally to the other side fence 45, and a pinion gear sandwiched between and meshing with both rack gear portions, and is provided with a pinion-rack mechanism.

[0029] Here, in the feeding tray 40 (sheet feeding device 13) in the present embodiment, in addition to the end fence 46 and the side fence 45 described above, a relay member 47, a rotating member 48, and a size detection unit 50 as size detection means are provided.

[0030] The relay member 47 is configured to be movable in the ±X direction (the direction of approaching and separating from the sheet P placed on the feeding tray 40) together with the end fence 46 as a fence member. Further, with reference to FIGS. 8, 12, etc., the relay member 47 is connected (coupled) to the end fence 46 as a fence member via a tension spring 49 as a biasing member.

[0031] Specifically, with reference to FIGS. 7, 10, etc., the relay member 47 is a member having a substantially "mountain" - shaped cross section, and is provided with a hook portion 47a, a rail portion 47b having a substantially T - shaped cross section, a fitting portion 47c that functions as a regulating means described later, an engaging portion 47d, and the like. Also, with reference to FIGS. 7, 9, etc., the end fence 46 (fence member) is a member having a substantially L - shaped cross section, and is provided with a hook portion 46a, a rail holding portion 46b, a pair of convex portions 46c, and the like. Furthermore, referring to FIGS. 7, 11, etc., the guide portion 44 is provided with two substantially concave members spaced apart from each other in the Y direction as a pair, and is provided with a groove portion 44a, a fitting portion 44b that functions as a regulating means described later, and the like.

[0032] And the guide portion 44 of the feed tray 40 is configured to guide the movement of the end fence 46 (fence member) and the relay member 47 in the ±X direction (the above-described "approach and separation direction"). Specifically, the end fence 46 is installed such that its convex portion 46c is fitted into the groove portion 44a of the guide portion 44, and is slidable in the ±X direction along the guide portion 44. Also, the relay member 47 is installed such that its rail portion 47b is slidably fitted into the rail holding portion 46b of the end fence 46, and its bottom portion is sandwiched between the pair of guide portions 44, and is slidable in the ±X direction along the guide portion 44. Furthermore, referring to FIGS. 7, 8, 12, etc., one end hook portion 49a of the tension spring 49 is connected to the hook portion 46a of the end fence 46, and the other end hook portion 49b is connected to the hook portion 47a of the relay member 47. In this way, the tension spring 49 functions as a biasing member that biases the relay member in the +X direction (the contact direction among the above-described "approach and separation directions") relative to the fence member. Note that FIG. 8 shows a state where the hook portions 49a, 49b of the tension spring 49 are not connected to the hook portions 46a, 47a in order to facilitate understanding of the shapes of the hook portions 49a, 49b of the tension spring 49.

[0033] With such a configuration, when the end fence 46 is moved in the +X direction along the guide portion 44 by a manual operation by the user (when it is moved in the +X direction beyond the "predetermined range" described later), the relay member 47 also moves in the +X direction by the spring force of the tension spring 49 so as to follow the end fence 46. On the other hand, when the end fence 46 is moved in the -X direction along the guide portion 44 by a manual operation by the user (when it is moved in the -X direction beyond the "predetermined range" described later), the relay member 47 is pushed by the end fence 46 and also moves in the -X direction. The movement of the relay member 47 in the ±X directions in conjunction with the movement of the end fence 46 in the ±X directions will be described in more detail later.

[0034] Here, referring to FIGS. 4(B), 5, 6, etc., the rotating member 48 is connected to the relay member 47 and is a substantially fan-shaped plate member that rotates in a predetermined rotation direction in conjunction with the movement of the relay member 47 in the ±X directions (the "approaching and separating direction" described above). That is, when the relay member 47 moves in the ±X directions in conjunction with the movement of the end fence 46 in the ±X directions, the rotating member 48 rotates in the forward and reverse directions about the rotation axis 48a (support shaft). Specifically, the rotating member 48 is rotatably held on the lower surface (back surface) of the feed tray 40 about the rotation axis 48a located between the guide portion 44 and the size detection portion 50. Further, the engaged portion 48c of the rotating member 48 (a long hole formed to extend in the radial direction at a position away from the rotation axis 48a) is engaged with the engaging portion 47d of the relay member 47 (projecting from the guide portion 44 toward the back surface of the tray). In other words, the engaging portion 47d of the relay member 47 is engaged with the long hole-shaped engaged portion 48c of the rotating member 48 so as to be relatively slidable. With such a configuration, when the relay member 47 (and the end fence 46) moves to the left in FIG. 4(B), the rotating member 48 rotates counterclockwise about the rotation axis 48a. On the other hand, when the relay member 47 (and the end fence 46) moves to the right in FIG. 4(B), the rotating member 48 rotates clockwise about the rotation axis 48a. Further, on the rotating member 48, a plurality of substantially comb-shaped protrusions 48b are formed along its outer peripheral surface at a position sufficiently separated from the engaging portion 47d on the opposite side across the rotation axis 48a.

[0035] Also, referring to FIGS. 4(B), 5, 6, etc., the size detection unit 50 functions as size detection means for detecting a corresponding sheet size among a plurality of sheet sizes (the sizes in the ±X directions of the sheet P) that can be placed on the feed tray 40, corresponding to the posture of the rotating member 48 in the rotation direction. Specifically, as shown in FIG. 6, the size detection unit 50 (size detection means) is provided with a plurality of push switches 50a (in the example of FIG. 6, six push switches 50a respectively installed at positions A to E) that are selectively pushed against the rotating member 48 according to the posture of the rotating member 48 in the rotation direction, corresponding to a plurality of sheet sizes (for example, A3, A4, A5 sizes, etc.). On the other hand, the plurality of protrusions 48b provided on the outer peripheral surface of the rotating member 48 are formed such that their circumferential lengths (arc lengths) are different from each other. Therefore, depending on the posture of the rotating member 48 in the rotation direction (the angle by which the rotating member 48 rotates), the number and position of the push switches 50a pushed into the rotating member 48 (protrusions 48b) will change. In the example of FIG. 6, five push switches 50a respectively installed at positions B to E are being pushed by the rotating member 48. With such a configuration, when the end fence 46 moves along the end face of the sheet P set on the feed tray 40 (in accordance with the sheet size), the rotating member 48 rotates via the relay member 47 in conjunction with this movement, and the push switch 50a corresponding to that sheet size is pushed into the rotating member 48, and that sheet size is detected. In this way, in the present embodiment, in conjunction with the linear movement of the end fence 46 (and the relay member 47), the rotating member 48 is rotated (the linear motion is converted into rotational motion), and the push switch 50a is turned on and off by the rotating member 48. Therefore, compared with the case where the push switch is configured to be turned on and off in conjunction with the linear movement of the end fence 46 (and the relay member 47), the size detection unit 50 can be miniaturized.

[0036] Here, referring to FIGS. 11(B), 12(B) to 15(B), etc., in the feeding tray 40 (sheet feeding device 13) in the present embodiment, with respect to the position of the corresponding sheet size detected by the size detection unit 50 (detection means), even if the end fence 46 (fence member) moves in the ±X direction (approach / separation direction) within a predetermined range W, the relay member 47 is restricted from moving in the ±X direction (approach / separation direction) by the fitting portion 44b and the fitting portion 47c (restriction means). In other words, the feeding tray 40 is provided with restriction means for restricting the relay member 47 from moving in the ±X direction even if the end fence 46 moves in the ±X direction within a predetermined range W with respect to the position of the target sheet size. That is, even if the end fence 46 moves in the ±X direction without exceeding a predetermined range W (not shown, for example, about ±1 to 4 mm) with respect to the position of the target sheet size (for example, A4 size), the movement of the relay member 47 in the ±X direction is restricted by the restriction means, and the rotating member 48 also does not rotate (the posture in the rotation direction does not change).

[0037] Specifically, referring to FIGS. 11(B), 12(B) to 15(B), etc., the plurality of fitting portions 44b are formed at intervals in the ±X direction (the "approach / separation direction") corresponding to the plurality of sheet sizes in the guide portion 44. Specifically, the fitting portion 44b is a concave portion formed to be recessed from the opposing surface facing the relay member 47 in the guide portion 44. On the other hand, the fitting portion 47c is formed in the relay member 47 so as to be fitted to the fitted portion 44b of the guide portion 44. Specifically, the fitting portion 47c is a convex portion (the corner portion is formed in a curved surface shape) formed at the tip of an arm portion extending in the +X direction from the side surface of the relay member 47. The arm portion on which the fitting portion 47c is formed is configured to be elastically deformable in the direction of the black arrow in FIG. 10(C). Due to the elastic deformation of this arm portion, the fitting portion 47c can be fitted to and removed from the fitted portion 44b. When the fitting portion 47c is fitted to one of the plurality of fitted portions 44b, the movement of the relay member 47 in the ±X direction along the guide portion 44 is restricted. That is, unless an external force greater than a predetermined magnitude acts, the fitting of the fitting portion 47c in the fitted portion 44b is not released, the relay member 47 cannot move, and the rotating member 48 also cannot rotate. In this way, the fitted portion 44b of the guide portion 44 and the fitting portion 47c of the relay member 47 function as a restricting means for restricting the movement of the relay member 47.

[0038] Hereinafter, with reference to FIGS. 12 to 14, the relationship between the procedure of manually operating the end fence 46 in the feeding tray 40 and the operation of the relay member 47 will be described. First, before the sheet P of a predetermined sheet size is set on the feeding tray 40, as shown in FIG. 12(A), the end fence 46 is moved (pushed in) in the white arrow direction (+X direction) along the guide portion 44 toward the position corresponding to the predetermined sheet size. At this time, as shown in FIG. 12(B), the relay member 47 moves in the white arrow direction (+X direction) along the guide portion 44 so as to follow the end fence 46 by the spring force of the tension spring 49 while getting over the other fitted portions 44b until the fitting portion 47c is fitted to the fitted portion 44b corresponding to the desired sheet size. Then, as shown in FIGS. 13(A) and (B), when the fitting portion 47c is fitted to the fitted portion 44b corresponding to the desired sheet size and the position of the end fence 46 in the ±X direction is determined, the sheet P (sheet bundle) is set on the feeding tray 40. At this time, the sheet P (sheet bundle) set on the feeding tray 40 may not be neatly aligned in the ±X direction, or there may be a state in which sheets with slightly different sizes in the ±X direction are mixed. As a result, the end fence 46 may be pushed back in the -X direction (white arrow direction) as shown in Fig. 14(A). Also, when the sheet P (sheet bundle) set on the feeding tray 40 is uniformly slightly misaligned in the -X direction, the end fence 46 may be pushed into the +X direction from the target position. In the present embodiment, even if the end fence 46 is displaced from the position of the target sheet size in this way, as long as the displacement amount does not exceed the predetermined range W, as shown in Fig. 14(B), the fitting of the fitting portion 47c to the fitted portion 44b is not released, and the relay member 47 is configured not to move in the ±X direction. Therefore, the posture of the rotating member 48 in the rotating direction does not change either, and there is no possibility that an unexpected push switch 50a is pushed in, and it is less likely that a problem of erroneously detecting the size of the sheet P placed on the feeding tray 40 occurs.

[0039] And such an effect is mainly due to (1) The rotating member 48 is configured to rotate indirectly in conjunction with the movement of the end fence 46 through the movement of the relay member 47, rather than directly rotating in conjunction with the movement of the end fence 46. (2) The relay member 47 is configured not to move directly in conjunction with the movement of the end fence 46 (for the +X direction, it moves indirectly in conjunction with the movement of the end fence 46 through the tension spring 49, and for the -X direction, it is configured to move in conjunction with the movement after moving to the position where the end fence 46 contacts). (3) A regulating means for regulating the movement of the relay member 47 in the ±X direction is provided. It is obtained by

[0040] Here, referring to FIG. 15, in this embodiment, in a state where the fitting portion 47c of the relay member 47 is fitted to one of the plurality of fitting portions 44b in the guide portion 44 (the state shown in FIGS. 13 and 14), when the end fence 46 (fence member) moves in the contact direction (+X direction, which is the direction of the white arrow in FIG. 15(A)) in the ±X direction (the direction of approaching and separating) beyond the predetermined range W (not shown), the relay member 47 is biased by the tension spring 49 (biasing member), and as shown in FIG. 15(B), the fitting of the fitting portion 47c to the fitting portion 44b is released. Specifically, when the use length of the tension spring 49 exceeds a predetermined length, the spring force thereof is formed to be greater than the force that restricts the movement of the relay member 47 by the restricting means (the force required for the fitting portion 47c to disengage from the fitting portion 44b). The "predetermined length" of the tension spring 49 at this time is a length set according to the "predetermined range W" of the end fence 46 described above. When the use length of the tension spring 49 is shorter than the "predetermined length", the fitting of the fitting portion 47c to the fitting portion 44b will not be released. By configuring in this way, the function of the restricting means for restricting the movement of the relay member 47 in the +X direction is ensured.

[0041] Also, referring to FIG. 16, in this embodiment, in a state where the fitting portion 47c of the relay member 47 is fitted to one of the plurality of fitting portions 44b in the guide portion 44 (the state shown in FIGS. 13 and 14), when the end fence 46 (fence member) moves in the separation direction (-X direction) in the ±X direction (the direction of approaching and separating) beyond the predetermined range W, the relay member 47 is pushed by the end fence 46, and the fitting of the fitting portion 47c to the fitting portion 44b is released. Specifically, as shown in FIG. 16, a stopper portion 46x that protrudes downward is formed at a position sandwiched between two convex portions 46c at the lower part of the end fence 46 in the +X direction. When the end fence 46 is moved in the -X direction with the fitting portion 47c fitted to the fitted portion 44b, eventually, as shown in FIG. 16, with the stopper portion 46x of the end fence 46 in contact with the end face of the relay member 47, the relay member 47 is pushed by the end fence 46 and moves in the -X direction along the guide portion 44. Therefore, the distance (clearance) from the state where the fitting portion 47c is fitted to the fitted portion 44b until the stopper portion 46x contacts the end face of the relay member 47 corresponds to the -X direction component of the "predetermined range W" in which the fitting of the fitting portion 47c to the fitted portion 44b is not released. By configuring in this way, the function of the restricting means for restricting the movement of the relay member 47 in the -X direction is ensured.

[0042] As described above, the sheet feeding device 13 in the present embodiment includes a feeding tray 40 on which the sheet P is placed, and an end fence 46 (fence member) that is configured to be movable in a direction of approaching and separating (±X direction) with respect to the end face of the sheet P placed on the feeding tray 40 to regulate the position of the sheet P. Further, a relay member 47 is provided that is connected to the end fence 46 via a tension spring 49 (biasing member) and is movable in the ±X direction (direction of approaching and separating) together with the end fence 46. Also, a rotating member 48 is provided that is connected to the relay member 47 and rotates in a predetermined rotation direction in conjunction with the movement of the relay member 47 in the ±X direction (direction of approaching and separating), and a size detection unit 50 (size detection means) that detects the corresponding sheet size among a plurality of sheet sizes that can be placed on the feeding tray 40 corresponding to the posture of the rotating member 48 in the rotation direction is provided. Furthermore, a fitted portion 44b and a fitting portion 47c (restricting means) are provided to restrict the relay member 47 from moving in the ±X direction (direction of approaching and separating) even when the end fence 46 moves in the ±X direction (direction of approaching and separating) within a predetermined range with respect to the position of the corresponding sheet size detected by the size detection unit 50. This can reduce the occurrence of a problem of erroneously detecting the size of the sheet P placed on the feeding tray 40.

[0043] In the present embodiment, the present invention is applied to the sheet feeding device 13 installed in the monochrome image forming apparatus 1. However, the present invention can naturally be applied to the sheet feeding device installed in a color image forming apparatus. Also, in the present embodiment, the present invention is applied to the sheet feeding device 13 installed in the electrophotographic image forming apparatus 1. However, the application of the present invention is not limited to this, and the present invention can also be applied to the sheet feeding device installed in other types of image forming apparatuses (for example, an inkjet type image forming apparatus, a stencil printing machine, etc.). And even in such cases, the same effects as those of the present embodiment can be obtained.

[0044] Further, in the present embodiment, the present invention is applied to the sheet feeding device 13 in which the rotating member 48 rotates by the movement of the relay member 47 linked to the movement of the end fence 46 as the fence member in the feeding direction (±X direction) to detect the sheet size in the feeding direction. On the other hand, the present invention can also be applied to a sheet feeding device in which the rotating member rotates by the movement of the relay member linked to the movement of the side fence 45 as the fence member in the width direction (±Y direction) to detect the sheet size in the width direction. Furthermore, the present invention can also be applied to a sheet feeding device that detects the sheet size in the feeding direction and also detects the sheet size in the width direction. And even in such cases, the same effects as those of the present embodiment can be obtained.

[0045] In addition, in the present embodiment, the present invention is applied to the sheet feeding devices 12 and 13 provided inside the image forming apparatus main body 1. However, the present invention can also be applied to the manual sheet feeding device 16 (see FIG. 17) as a sheet feeding device installed so as to protrude to the side of the image forming apparatus main body 1. Furthermore, the present invention can also be applied to the document conveyance unit 10 as a sheet feeding device that feeds the document D as a sheet. Note that the sheet feeding device 16 (manual sheet feeding device) shown in FIG. 17 is configured in substantially the same manner as the sheet feeding device 13 described with reference to FIGS. 3 to 16, except that (1) the feeding tray 40 (manual tray) is not formed in a substantially box shape but is formed in a substantially flat plate shape, and (2) the direction in which the sheet P is fed is the -X direction. And even in such cases, the same effects as those of the present embodiment can be obtained.

[0046] It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be appropriately modified within the scope of the technical idea of the present invention, other than those suggested in the present embodiment. Also, the number, position, shape, etc. of the above-described constituent members are not limited to the present embodiment, and can be set to appropriate numbers, positions, shapes, etc. suitable for implementing the present invention.

[0047] In the present specification and the like, the term "sheet" is defined to include all sheet-like recording media (including documents), such as coated paper, label paper, OHP sheets, metal sheets, films, prepregs, cloth, etc., in addition to ordinary paper.

Explanation of Reference Numerals

[0048] 1 Image forming apparatus (image forming apparatus main body), 13 Sheet feeding device, 40 Feeding tray (sheet placement device), 43 Side fence guide portion, 44 End fence guide portion (guide portion), 44a Groove portion, 44b Fitted portion (restricting means), 45 Side fence, 46 End fence (fence member), 46a Hanging part, 46b Rail holding part, 46c Protruding part, 46x Stopper part, 47 Relay member, 47a Hanging part, 47b Rail part, 47c Fitting part (restricting means), 47d Engaging part, 48 Rotating member (lever), 48a Rotation axis, 48b Protrusion, 48c Engaged part, 49 Tension spring (biasing member), 49a, 49b Hook parts, 50 Size detection part (size detection means), 50a Push switch, P sheet.

Prior Art Documents

Patent Documents

[0049]

Patent Document 1

Claims

1. A sheet feeding tray on which a sheet is placed, a fence member configured to be movable in a direction of approaching and separating from an end face of the sheet placed on the sheet feeding tray, and regulating the position of the sheet, a relay member connected to the fence member via a biasing member and movable in the approaching and separating direction together with the fence member, a rotating member connected to the relay member and rotating in a predetermined rotation direction in conjunction with the movement of the relay member in the approaching and separating direction, size detection means for detecting a corresponding sheet size among a plurality of sheet sizes that can be placed on the sheet feeding tray, corresponding to the posture of the rotating member in the rotation direction, regulating means for regulating so that the relay member does not move in the approaching and separating direction even when the fence member moves in the approaching and separating direction within a predetermined range with respect to the position of the corresponding sheet size detected by the detection means, A sheet feeding device characterized by comprising the above.

2. The sheet feeding tray includes a guide portion for guiding the movement of the fence member and the relay member in the approaching and separating direction, The regulating means is, in the guide portion, a plurality of fitting portions formed at intervals in the approaching and separating direction corresponding to the plurality of sheet sizes respectively, in the relay member, a fitting portion formed to be fitted to the fitting portion, The sheet feeding device according to claim 1, characterized in that it is as described above.

3. When the fitting portion of the relay member is fitted to one of the plurality of fitting portions in the guide portion and the fence member moves in the contact direction in the approaching and separating direction beyond the predetermined range, the relay member is biased by the biasing member, and the fitting of the fitting portion to the fitting portion is released. The sheet feeding device according to claim 2, characterized in that it is as described above.

4. When the fitting portion of the relay member is fitted to one of the plurality of fitting portions in the guide portion and the fence member moves in the separation direction in the approaching and separating direction beyond the predetermined range, the relay member is pushed by the fence member, and the fitting of the fitting portion to the fitting portion is released. The sheet feeding device according to claim 2 or claim 3, characterized in that it is as described above.

5. The urging member is a tension spring that urges the relay member relative to the fence member in the contact direction among the approaching and separating directions, and the sheet feeding device according to any one of claims 1 to 4 is characterized in that.

6. The tension spring is formed such that when its use length exceeds a predetermined length, its spring force becomes larger than the force that restricts the movement of the relay member by the restricting means, and the sheet feeding device according to claim 5 is characterized in that.

7. The size detection means includes a plurality of push switches that are selectively pushed against the rotating member according to the posture of the rotating member in the rotating direction corresponding to the plurality of sheet sizes, and the sheet feeding device according to any one of claims 1 to 6 is characterized in that.

8. An image forming apparatus comprising the sheet feeding device according to any one of claims 1 to 7 is characterized in that.

Images