JP6597170B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including an image forming unit and a paper feeding unit including a detachable paper feeding cassette for supplying paper to the image forming unit.

  An image forming apparatus such as a copying machine or a printer is usually provided with a paper feeding unit including a detachable paper feeding cassette for supplying paper to the image forming unit. This paper feed unit is equipped with a pickup roller that feeds the paper stacked on the paper stacking table of the paper cassette one by one and a roller holder that pivotally supports the pickup roller. The roller holder displaces the pickup roller in the vertical direction. It can be rotated around an axis parallel to the axis of the pickup roller. For example, when pulling out the paper cassette for paper replenishment (especially in the case of a structure that pulls out the paper cassette in the direction perpendicular to the paper transport direction), to avoid interference between the paper cassette and the pickup roller The roller holder is rotated so that the pickup roller is displaced upward (see, for example, Patent Document 1).

  Further, a sheet sensor movable piece extending in the direction opposite to the pickup roller from the rotation axis of the roller holder is provided. When the roller holder rotates and the pickup roller is displaced upward, the leading end of the sheet sensor movable piece extending in the opposite direction is displaced downward. For example, when a paper feed (double feed) occurs at the end of the previous printing and there is residual paper in the paper feed path, the tip of the paper sensor movable piece comes into contact with the residual paper and stops rotating. Therefore, it is possible to detect the presence or absence of residual paper by detecting the rotation position of the paper sensor movable piece with an optical sensor or the like.

Japanese Patent Laying-Open No. 2015-131715

  In the conventional image forming apparatus as described above, when the roller holder is rotated so that the pickup roller is displaced upward, the tip of the sheet sensor movable piece is displaced downward and comes into contact with the remaining sheet. The tip of the paper sensor movable piece may break through the residual paper without stopping the rotation of the roller holder. Even if it does not reach the end, damage such as dents is given to the remaining paper. In this case, there may be a problem that it takes time to remove the remaining paper and its fragments. Further, if the leading end of the sheet sensor movable piece breaks through the remaining sheet and rotates, the remaining sheet cannot be detected correctly.

  In view of the above-described problems, the present invention is configured such that when the leading end portion of the sheet sensor movable piece is displaced downward along with the rotation of the roller holder when the sheet feeding cassette is pulled out, the leading end portion removes residual paper. It is an object of the present invention to provide an image forming apparatus having a structure that does not break through or cause damage such as dents.

The image forming apparatus according to claim 1 includes an image forming unit and a paper feeding unit including a detachable paper feeding cassette for feeding paper to the image forming unit, and the paper feeding unit includes the paper feeding unit. A pickup roller that feeds the sheets stacked on the paper stacking unit of the paper cassette one by one; and a roller holder that pivotally supports the pickup roller, wherein the roller holder is configured to displace the pickup roller in a vertical direction. A sheet sensor movable piece that is rotatable about an axis parallel to the axis of the pickup roller and that extends in the opposite direction to the pickup roller from the axis of rotation of the roller holder is provided, and the sheet feeding cassette is pulled out. In order to avoid interference between the pickup roller and the paper feed cassette, the roller holder is rotated and moved forward. An image forming apparatus configured such that a pickup roller is displaced upward, and a leading end portion of the sheet sensor movable piece extending in a direction opposite to the pickup roller is displaced downward as the roller holder rotates. Suruga, when the tip is in contact with the remaining paper, the provided tip portion of the roller holder is also rotated the paper sensor movable piece is configured so as not to be displaced further, the paper sensor movable piece Is divided into a first member on the proximal end side and a second member on the distal end side, and the first member and the second member are engaged with each other so that they can be bent around the rotation axis of the roller holder. When the tip of the second member is displaced downward and comes into contact with the remaining paper, the first member rotates following the rotation of the roller holder, but the second member So Characterized in that it is configured not to displace more.

The image forming apparatus according to claim 2, in the image forming apparatus according to claim 1, wherein the first member and the second member is urged into the engaged state by the biasing means, the biasing of said biasing means It is configured to bend when a force greater than a force is applied.

The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1 or 2, further comprising a feed roller and separation roller for conveying by sandwiching the sheet fed from the pickup roller, the roller The holder supports the pickup roller and the paper feed roller, and is rotatable about the axis of the paper feed roller.

  According to the image forming apparatus of the first aspect, when the paper feed cassette is pulled out, the leading end of the sheet sensor movable piece extending in the opposite direction to the pickup roller is displaced downward as the roller holder rotates. However, when the leading edge abuts on the remaining paper, the leading edge of the paper sensor movable piece is not further displaced even if the roller holder rotates. Will not break through or cause damage such as dents.

As a specific structure, the paper sensor movable piece is divided into the second member of the first member and the distal end side of the base end side, even if the first member rotates to follow the rotation of the roller holder, the A structure is provided in which the two members do not displace further from the state in which they contact the remaining paper. Further , a structure is provided in which the first member and the second member are engaged with each other so that they can be bent around the rotation axis of the roller holder.

According to the image forming apparatus according to claim 2, bent when biased in the engaged state, the urging force is greater than force of the biasing means is applied by the first member and the second member urging means It is configured in this way, while ensuring the function of detecting the residual paper by the paper sensor movable piece, it prevents the paper sensor movable piece from breaking through the residual paper or causing damage due to the rotation of the roller holder. Can do.

According to the image forming apparatus of the third aspect , the paper feeding roller that transports the paper fed from the pickup roller while being sandwiched between the picking roller is pivotally supported by the roller holder together with the pickup roller, and the roller holder is rotated. A reasonable structure is provided in which the dynamic axis is the axis of the feed roller.

2 is a schematic diagram illustrating an internal configuration of a printer unit of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a schematic configuration of a sheet feeding cassette of a sheet feeding unit and its periphery. FIG. 4 is a schematic diagram illustrating a schematic configuration of a paper feed cassette and its surroundings in a state where a paper stacking base is lowered. It is a schematic diagram which shows the state which the roller holder rotated and the pickup roller raised. FIG. 3 is a schematic diagram illustrating a schematic configuration of a paper feed cassette and its periphery when there is residual paper in a paper feed path. It is a perspective view of a sheet sensor movable piece of a conventional example. It is a perspective view of the rotation unit by which the paper sensor movable piece of the prior art example, the pick-up roller, and the paper feed roller were pivotally supported by the roller holder. It is a perspective view of the rotation unit which concerns on embodiment of this invention. It is a perspective view of a sheet sensor movable piece according to an embodiment of the present invention. It is a side view of a sheet sensor movable piece according to an embodiment of the present invention. It is a side view which shows the state in which the paper sensor movable piece of FIG. 10 was bent.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. First, a schematic configuration of the printer unit of the image forming apparatus according to the embodiment will be described. The image forming apparatus according to the present embodiment is an electrophotographic color copier, a color multifunction peripheral, or the like, and the internal configuration of the printer unit is schematically shown in FIG.

  The image forming apparatus (printer unit) includes an image forming unit 10, a paper feeding unit 20, a fixing unit 30, a control unit 60, and the like. A toner image is formed by the image forming unit 10 based on image data of the document read by the document reading device or image data received from an external device such as a computer via a communication line, and is supplied from the paper feeding unit 20. The toner image is transferred and fixed on the paper. That is, electrophotographic printing is performed.

  The image forming unit 10 includes a total of four image forming units 2 corresponding to respective colors of yellow (Y), magenta (M), cyan (C), and black (K), an intermediate transfer belt 11, and the like. The four image forming units 2 are arranged below the intermediate transfer belt 11 along the intermediate transfer belt 11 in the order of yellow, magenta, cyan, and black from the left in FIG. In FIG. 1, the four image forming units 2 are displayed as 2Y, 2M, 2C, and 2K with symbols Y, M, C, and K corresponding to the respective colors. Each image forming unit 2 includes a photosensitive drum 3 that rotates clockwise as indicated by an arrow. Around the photosensitive drum 3, a charging unit 4, an exposure unit 5, A developing unit 6, a primary transfer roller 7, and a photoreceptor cleaner 8 are arranged. Note that reference numbers 4 to 8 of these apparatuses are described only in the image forming unit 2Y in FIG. 1 and omitted in the other image forming units 2M, 2C, and 2K.

  Laser light modulated based on image data to be printed is emitted from the exposure unit 5 and deflected in the axial direction of the photosensitive drum 3. The surface of the photosensitive drum 3 that has been uniformly charged by the charging unit 4 is two-dimensionally scanned with laser light as it rotates, and an electrostatic latent image corresponding to image data is formed. Next, the electrostatic latent image on the surface of the photosensitive drum 3 is developed with toner by the action of the developing unit 6 to form a toner image.

  The intermediate transfer belt 11 is wound around a driving roller 12, a driven roller 13, and a tension roller 14, and rotates in a counterclockwise direction as indicated by an arrow in FIG. The primary transfer roller 7 of each image forming unit 2 is disposed inside the intermediate transfer belt 11, and the intermediate transfer belt 11 moves while being sandwiched between the primary transfer roller 7 and the photosensitive drum 3. A primary transfer nip is formed between the intermediate transfer belt 11 and the photosensitive drum 3.

  Each color toner image formed on the surface of the photosensitive drum 3 of each image forming unit 2 is sequentially transferred to the intermediate transfer belt 11 at each primary transfer nip. The toner images of yellow, magenta, cyan, and black are transferred so as to overlap each other in order, and a color toner image is formed on the intermediate transfer belt 11. The toner remaining on the surface of the photoconductive drum 3 after the primary transfer is scraped off by the photoconductive cleaner 8, and the surface of the photoconductive drum 3 is cleaned in preparation for the next charging, exposure, development or the like.

  The color toner image formed on the intermediate transfer belt 11 is secondarily transferred to a sheet at a secondary transfer nip provided on the downstream side of each image forming unit 2 in the circumferential direction of the intermediate transfer belt 11. A secondary transfer roller 25 is disposed outside the portion of the intermediate transfer belt 11 wound around the drive roller 12, and a secondary transfer nip 15 is formed between the intermediate transfer belt 11 and the secondary transfer roller 25. Yes. When the paper P fed from the paper supply unit 20 passes through the secondary transfer nip 15 through the paper transport path (main transport path R0), the color toner image on the intermediate transfer belt 11 is secondarily transferred to the paper P. Is done.

  The toner remaining on the surface of the intermediate transfer belt 11 after the secondary transfer is scraped off by the transfer belt cleaner 16. The transfer belt cleaner 16 is disposed outside the portion of the intermediate transfer belt 11 that is wound around the driven roller 13. Thus, the surface of the intermediate transfer belt 11 is cleaned in preparation for the next primary transfer and secondary transfer.

  The paper P on which the toner image has been transferred through the secondary transfer nip 15 passes through the fixing unit 30 located on the downstream side of the transport path (main transport path R0). The fixing unit 30 includes a fixing roller 31 including a fixing heater 33 such as a halogen lamp, and a pressure roller 32 facing the fixing roller 31. The paper P onto which the toner image has been transferred is heated and pressurized when passing through a fixing nip that is a contact portion between the fixing roller 31 and the pressure roller 32, and the toner image is fixed on the paper P. The paper P on which the toner image is fixed is discharged to the outside (on the paper discharge tray) by the discharge roller pair 38.

  The paper feed unit 20 includes a detachable paper feed cassette 21 that accommodates the paper P. When the paper P is replenished, the paper feed cassette 21 is pulled out in a direction perpendicular to the paper conveyance direction (a direction perpendicular to the paper surface in FIG. 1). In addition, a pickup roller 41 that feeds the paper P in the paper feed cassette 21 one by one, a paper feed roller 42 that is a pair of paper feed rollers that sandwich the fed paper and transport it to the paper feed path R1, and a rolling roller 43 are provided. It has been.

  A registration roller pair 24 that takes a timing to feed the paper P to the secondary transfer nip 15 is disposed in a portion that transitions from the paper feed path R1 to the main transport path R0. The paper sent out to the paper feed path R <b> 1 is temporarily stopped in a state where its front end is abutted against the registration roller pair 24. As a result, positioning in the transport direction of the paper P is performed, and the paper P is moved from the paper feed path R1 to the main transport path R0 at the timing synchronized with the toner image formation and primary transfer in the image forming unit 10, that is, the secondary transfer. It is sent out to the nip 15.

  Paper sensors (for example, photosensors) that detect the presence or absence of the paper P are arranged at a plurality of locations on the paper transport path including the paper feed path R1 and the main transport path R0. In FIG. 1, only the paper sensor 34 disposed on the upstream side of the registration roller pair 24 and the paper sensor 35 disposed on the downstream side of the fixing unit 30 are illustrated. The paper sensors arranged at other locations are not shown.

  The detection signal of each paper sensor is input to the control unit 60. The control unit 60 determines the passage timing of the front end or the rear end of the paper P based on the detection signal of each paper sensor, and activates the motors and the like of each unit. The stop timing can be controlled. For example, the control unit 60 measures the time from when the front edge of the paper P passes through the paper sensor 34 to when the rear edge of the paper P passes through the paper sensor 34 using a built-in timer, and at the measured time, the paper By multiplying the conveyance speed, the size of the paper P (the length in the conveyance direction) is calculated. Then, the registration roller pair 24 is driven to rotate for a time corresponding to the paper size.

  Next, the schematic configuration of the paper feed cassette 21 of the paper feed unit 20 and its periphery is shown in FIG. 2 as a schematic diagram. The paper feed cassette 21 includes a paper stacking table 45 on which a plurality of paper sheets P are stacked in a box. The sheet stacking table 45 can swing up and down (up and down) about the axis AX1 on the opposite side of the front end side (side closer to the pickup roller 41) of the sheet P. Further, the paper feeding unit 20 is provided with an elevating mechanism 46 for elevating and lowering the paper stacking table 45 and an elevating motor 47 as an elevating drive means.

  When the right end of the lifting mechanism 46 swings up and down around the axis AX2 of the left end by driving the lifting motor 47, the right side of the paper stacking table 45 (the front end side of the paper P) is accordingly the axis of the left end. It is configured to swing up and down (up and down) around AX1. When the lifting motor 47 is rotated forward, the paper stacking table 45 is raised, and when the lifting motor 47 is rotated reversely, the paper stacking table 45 is lowered.

  When the pickup roller 41 rotates with the pickup roller 41 in contact with the upper surface of the stacked paper P at a predetermined pressure as shown in FIG. The uppermost sheet P is sent out to the nip between the sheet feeding roller 42 and the separating roller 43. The paper feed roller 42 and the separation roller 43 sandwich the paper P and transport it from the paper feed path R1 to the registration roller pair 24. The registration roller pair 24 takes the paper P while taking operation and timing in the image forming unit 10. It is sent out to the main transport path R0, that is, to the secondary transfer nip 15.

  The pickup roller 41 and the paper feed roller 42 are pivotally supported by a common roller holder 40. The roller holder 40 is centered on the axis AX3 of the paper feed roller 42, and the pickup roller 41 side has a predetermined range up and down as indicated by arrows. It can be swung within. Further, a force F that pushes the pickup roller 41 downward is exerted by its own weight (gravity moment) of the pickup roller 41 and the roller holder 40 or by applying a biasing force by a biasing means such as a spring. By this force F, the pickup roller 41 comes into contact with the upper surface of the paper P stacked on the paper stacking table 45 with a predetermined pressure.

  FIG. 3 shows a schematic configuration of the paper feed cassette 21 and its periphery with the paper stacking table 45 lowered. When the paper stacking table 45 is lowered by the reverse rotation of the lift motor 47, the roller holder 40 swings and the pickup roller 41 is also lowered accordingly. The upper surface of the paper P loaded on the paper stacking table 45 is separated from the pickup roller 41. In this state, the paper P cannot be sent out even if the pickup roller 41 rotates.

  FIG. 4 shows a schematic configuration of the paper feed cassette 21 and its surroundings in a state where the roller holder 40 is largely rotated and the pickup roller 41 is raised. For example, in order to avoid interference between the paper feed cassette 21 and the pickup roller 41 when the paper feed cassette 21 is pulled out, the roller holder 40 is centered on the axis AX3 of the paper feed roller 42 as shown in FIG. A large rotation causes the pickup roller 41 to rise.

  FIG. 5 is a schematic diagram showing how a sheet is detected when there is a remaining sheet in the sheet feed path. As shown in FIGS. 2 to 5, a sheet sensor movable piece 48 extending from the rotation axis AX3 of the roller holder 40 in the opposite direction to the pickup roller 40 is provided, and the roller holder 40 is rotated so that the pickup roller 41 is raised. When moved, the sheet sensor movable piece 48 (the front end thereof) is displaced downward.

  For example, in the previous printing, when a paper feed (double feed) occurs and there is residual paper P in the paper feed path, the tip of the paper sensor movable piece 48 hits the residual paper P as shown in FIG. In this state, the rotation of the roller holder 40 stops. Therefore, if the optical sensor is arranged at the position OP indicated by the X in FIGS. 4 and 5, the presence or absence of the residual paper P is detected by detecting the rotational position of the paper sensor movable piece 48 by the optical sensor. be able to. For example, the light-emitting side and the light-receiving side of a transmissive optical sensor may be provided so as to sandwich the paper surface at a position OP indicated by a mark X in FIGS. In this case, the paper sensor movable piece 48 blocks the optical path from the light emitting side to the light receiving side in the state of FIG. 5 with the residual paper P, but in the state of FIG. 4 without the residual paper P, the light is blocked from the light emitting side to the light receiving side. Therefore, the control device 60 can determine both states based on the output signal on the light receiving side.

  However, in the conventional structure, when there is residual paper P, the rotation of the roller holder 40 does not stop in the state of FIG. 5, and the tip of the paper sensor movable piece 48 breaks through the residual paper P and the state of FIG. May turn up to. Even if it does not break through, damage such as dents is given to the residual paper P. In this case, there is a problem that it takes time to remove the residual paper P and its fragments. Further, if the sheet sensor movable piece 48 breaks through the residual paper P and rotates to the state shown in FIG. 4, the residual paper P cannot be detected correctly. That is, the control device 60 erroneously determines that there is no residual paper P. In order to avoid the occurrence of such a problem, in the image forming apparatus of this embodiment, the following device is added to the structure of the sheet sensor movable piece 48.

  First, a perspective view of a conventional sheet sensor movable piece 48 is shown in FIG. FIG. 7 shows a rotating unit in which the sheet sensor movable piece 48, the pickup roller 41, and the paper feed roller 42 are pivotally supported by the roller holder 40. As shown in FIG. 7, the rotation shaft 41 </ b> S of the pickup roller 41 and the rotation shaft 42 </ b> S of the paper feed roller 42 are arranged in parallel and are pivotally supported by the roller holder 40. The sheet sensor movable piece 48 is also pivotally supported on the roller holder 40 via the rotation shaft 42S of the sheet feeding roller 42.

  As shown in FIG. 6, the sheet sensor movable piece 48 is an integral member formed of resin or metal, and includes a first engagement portion (long hole) 481 through which the rotation shaft 41 </ b> S of the pickup roller 41 is inserted, The second engaging portion (round hole) 482 through which the rotation shaft 42S of the paper feeding roller 42 is inserted, the light shielding portion 483 that blocks the optical path of the optical sensor as described above, and the leading end portion 484 that contacts the upper surface of the residual paper P. And. The first engagement portion 481 is a long hole that allows vertical displacement (swing of the roller holder 40) within a predetermined range of the pickup roller 41 as described above. When the roller holder 40 rotates greatly beyond the swing range and the pickup roller 41 moves up, the sheet sensor movable piece 48 rotates with the roller holder 40 as shown in FIGS. Part 484 is lowered.

  Next, FIG. 8 shows a perspective view of the rotating unit according to the embodiment of the present invention. Further, a perspective view of the sheet sensor movable piece 48 is shown in FIG. 9, and a side view thereof is shown in FIG. As shown in FIG. 8, the rotating shaft 41S of the pick-up roller 41 and the rotating shaft 42S of the paper feed roller 42 are arranged in parallel and are pivotally supported by the roller holder 40 to constitute a rotating unit in FIG. This is the same as the conventional example. Further, the sheet sensor movable piece 48 is pivotally supported by the roller holder 40 via the rotation shaft 42S of the sheet feeding roller 42, which is the same as the conventional example of FIG.

  Whereas the sheet sensor movable piece 48 of the conventional example is an integral member, the sheet sensor movable piece 48 according to the embodiment of the present invention is a first member on the base end side as shown in FIGS. It is divided into 48A and a second member 48B on the front end side, and both members are engaged so as to be bent. A second engagement portion (round hole) 482 through which the rotation shaft 42S of the paper feed roller 42 is inserted is formed in both the first member 48A and the second member 48B, and both members are the rotation shaft 42S of the paper feed roller 42, That is, the roller holder 40 is engaged so that it can be bent about the rotation axis. Further, a torsion coil spring 49 is provided to urge the first member 48A and the second member 48B into an engaged state in which the first member 48A and the second member 48B extend straight, one end 491 is fixed to the first member 48A, and the other end 492 is the second member. It is fixed to 48B.

  Also, a first engagement portion (long hole) 481 through which the rotation shaft 41S of the pickup roller 41 is inserted is formed in the first member 48A, and contacts the light shielding portion 483 that blocks the optical path of the optical sensor and the upper surface of the residual paper P. A front end portion 484 is formed on the second member 48B. As can be seen from FIG. 9, the light-shielding portion 483 is formed in a step shape in plan view with respect to the peripheral portion of the second engaging portion 482, but like the conventional sheet sensor movable piece 48 shown in FIG. In addition, the light shielding portion 483 may be formed to extend straight from the peripheral portion of the second engaging portion 482.

  FIG. 11 shows a state where the sheet sensor movable piece 48 having the above structure is bent. As described above, when the roller holder 40 is rotated in the direction in which the pickup roller 41 is raised and the leading end 484 of the sheet sensor movable piece 48 is displaced downward, the leading end 484 of the sheet sensor movable piece 48 is the remaining paper. When abutting on P, the first member 48A rotates as shown by the arrow following the rotation of the roller holder 40, but the second member 48B is not displaced any further. That is, as shown in FIG. 11, the first member 48A and the second member 48B are bent around the rotation axis of the roller holder 40, that is, the axis of the paper feed roller 42, so that the second member 48B has its tip. The portion 484 is not displaced further from the state where it abuts against the residual paper P.

  As described above, the first member 48A and the second member 48B are bent when the front end portion 484 of the second member 48B contacts the residual paper P and receives a reaction force from the residual paper P. It is necessary to set the biasing force (torsion restoring force) of the torsion coil spring 49 sufficiently small. That is, as the coil spring 49, one having a small number of windings formed of a relatively thin wire rod is used.

  By using the sheet sensor movable piece 48 having the above-described structure, the image sensor including the sheet feeding unit according to the present embodiment causes the sheet sensor movable piece 48 to move down by the rotation of the roller holder 40 and the remaining sheet. When the residual paper P is detected in contact with P, there is no possibility that the leading end portion 484 of the paper sensor movable piece 48 will break through the residual paper P or cause damage such as a dent to the residual paper P. Therefore, the problem that the remaining paper P is not correctly detected does not occur. Further, there is no problem that it takes time to remove the residual paper P and its fragments.

  Although the embodiments of the present invention have been described above, the shape and structure of each part are not limited to the specific ones described with reference to the drawings, and various modifications can be made without departing from the spirit of the present invention. It is. For example, in the above embodiment, the torsion coil spring 49 that biases the first member 48A and the second member 48B constituting the sheet sensor movable piece 48 into an engaged state in which the sheet sensor movable piece 48 extends straight is provided. 49 may be omitted, and the leading end portion 484 may be lowered by the dead weight (gravity moment) of the second member 48B, and if there is a residual sheet P, the structure may be in contact therewith.

  Further, the center of bending of the first member 48A and the second member 48B of the sheet sensor movable piece 48 is not limited to the rotation axis of the roller holder 40, that is, the rotation axis of the paper feed roller 42, but at other positions. Also good. For example, the sheet sensor movable piece 48 may be bent at a position close to the leading end 484.

  Further, the rotation axis of the roller holder 40 is not the rotation axis of the paper feed roller 42, that is, around an axis that is different from the rotation axis of the paper feed roller 42 (an axis parallel to the axis of the pickup roller). The sheet sensor movable piece 48 having a bent structure according to the present invention may be applied to a structure in which the pickup roller 41 moves up and down as the roller holder 40 rotates.

DESCRIPTION OF SYMBOLS 10 Image formation part 20 Paper feed part 40 Roller holder 41 Pickup roller 42 Paper feed roller 43 Rolling roller 48 Paper sensor movable piece 484 Tip part 48A 1st member 48B 2nd member 49 Torsion coil spring

Claims (3)

An image forming unit, and a sheet feeding unit including a detachable sheet feeding cassette for supplying sheets to the image forming unit, wherein the sheet feeding unit is a sheet stacked on a sheet stacking table of the sheet feeding cassette A pick-up roller that feeds the pick-up roller one by one and a roller holder that pivotally supports the pick-up roller, and the roller holder rotates around an axis parallel to the axis of the pick-up roller so as to displace the pick-up roller in the vertical direction. And a sheet sensor movable piece extending in a direction opposite to the pickup roller from a rotation axis of the roller holder is provided, and the pickup roller and the sheet cassette are drawn when the sheet cassette is pulled out. In order to avoid interference with the roller holder, the roller holder rotates and the pickup roller moves upward. A the image forming apparatus configured as ordinating,
As the roller holder rotates, the leading end of the sheet sensor movable piece extending in the opposite direction to the pickup roller is displaced downward, but when the leading end abuts on the remaining sheet, the roller holder Even if it is rotated, it is configured so that the tip of the paper sensor movable piece is not displaced further ,
The sheet sensor movable piece is divided into a first member on the proximal end side and a second member on the distal end side,
The first member and the second member are engaged with each other so that they can be bent around a rotation axis of the roller holder,
When the tip of the second member is displaced downward and comes into contact with the remaining paper, the first member rotates following the rotation of the roller holder. An image forming apparatus configured to prevent displacement . The first member and the second member are biased into an engaged state by a biasing unit, and are configured to bend when a force larger than a biasing force of the biasing unit is applied. Item 2. The image forming apparatus according to Item 1 . The apparatus further includes a paper feed roller and a scoop roller that sandwich and convey the paper fed from the pickup roller, and the roller holder pivotally supports the pickup roller and the paper feed roller, and a shaft of the paper feed roller. the image forming apparatus according to claim 1 or 2, characterized in that it is pivotable about heart.

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