JP2014019502A - Sheet feeder, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide simply-configured sheet feeder and image forming apparatus, which enable assembly of a friction pad-type sheet feed-separation device for preventing a multiple-sheet feed.SOLUTION: A paper feeder, including: feed means for feeding a sheet; separation means for separating a sheet fed from the feed means; first energizing means 304 for energizing the separation means in a direction of pressing feed means 30a; and a structure member 305 for supporting the first energizing means, further includes: first movement inhibition means 307 having a first surface and a second surface that is inclined relative to the first surface. Further, the first movement inhibition means is inclined so that the second surface is inclined in a direction in which an end of the second surface is separated from the first surface in a mounting direction of the first movement inhibition means. The first movement inhibition means is retained so that the first surface contacts with the structure member while the first surface contacts with the separation means and inhibits the separation means from moving in a direction reverse to pressing direction.

Description

  The present invention relates to a paper feeding device provided in a copying machine, a facsimile, a printer, a printing machine, or an ink jet recording apparatus. Furthermore, the present invention relates to an image forming apparatus combining at least one of these.

  In image forming apparatuses such as copying machines, printers, facsimiles, etc., developments for improving the quality are being carried out every day. One factor that improves the quality of the image forming apparatus is paper conveyance quality. In recent years, papers used in image forming apparatuses have become diverse, and it is particularly essential to improve the quality of paper feed and separation. Therefore, in order to improve the quality of paper feeding / separation, configurations of an RF method, an FRR method, and the like in which a separation roller is mounted on a separation mechanism are already known.

  However, configurations such as the RF method and the FRR method are not suitable for use in low-end machines because of the high cost of the members. In order to improve the quality of paper feeding / separation in low-end machines, it is already known to employ a friction pad system that is lower in cost than the RF system and FRR system.

  Hereinafter, a sheet feeding device using the friction pad method will be described with reference to FIG.

  FIG. 9A is an enlarged side view showing a paper feeding unit of a paper feeding device using a conventional friction pad system. The paper P stacked on the bottom plate 301 is pressed against the paper supply roller 30a. When a plurality of sheets are fed from the sheet P stacked on the bottom plate 301, a predetermined pressure is applied to the separation nip portion of the sheet feeding roller 30a and the friction pad 302 in order to frictionally separate the plurality of sheets. Will be added.

  Specifically, a predetermined pressure is applied to the separation nip portion by a separation spring 304 that biases the friction pad receiving base 303 that holds the friction pad 302. When the sheets are overlapped and fed, only the uppermost sheet is frictionally separated and fed at the separation nip portion. When the friction coefficient μr between the paper feed roller 30a and the paper P, the friction coefficient μp between the papers, and the friction coefficient μf between the paper P and the friction pad 302, the relationship between the respective friction coefficients is μr> μf. > Μp, and only the uppermost paper is separated and fed due to the difference in frictional force. Further, the friction coefficient μf can be changed by changing the pad material of the friction pad 302 or the like.

  However, a paper feeding device using such a friction pad system cannot adjust the pressure applied to the separation nip portion and has poor paper handling capability. In addition, when sheets are replenished or when sheets that are easy to double feed (multi-sheet feeding) are used, the sheets stacked on the bottom plate 301 may enter the separation nip portion as a bundle. At this time, as shown in FIG. 9B, the force by which the bundled sheets P push down the friction pad receiving base 303 via the friction pad 302 causes the friction pad receiving base 303 to pass through the separation spring 304. It becomes larger than the force that pushes up.

  Therefore, the friction pad 302 moves away from the paper feed roller 30a, and a separation nip cannot be formed between the paper feed roller 30a and the friction pad 302, and an appropriate frictional force for separating the paper cannot be generated. . As a result, this may cause the occurrence of multi-sheet feeding (multi-feed) in which a plurality of sheets are conveyed while being overlapped, or the occurrence of double-feed jam (catch-feed jam). Further, when the pad material of the friction pad 302 is changed, a sufficient effect for preventing the occurrence of such double feeding cannot be obtained.

  Further, when the friction pad receiving base 303 that supports the friction pad 302 on the upstream side in the sheet conveyance direction has the rotation shaft 303a on the downstream side in the conveyance direction of the sheet P, there is a possibility of causing non-feeding.

  Specifically, when a sheet such as a rigid thick sheet is sent to the separation nip portion, the friction pad receiving base 303 is pushed down. Therefore, an angle formed by a tangential plane formed by contact between the friction pad 302 and the sheet feeding roller 30a and a plane formed by the feeding direction of the sheet to the separation nip portion (hereinafter referred to as “sheet entry angle”). ) Will grow. As a result, the relationship between the friction coefficients becomes μr <μf, and the resistance force that the sheet receives from the friction pad 302 increases, which may lead to non-feeding.

  Therefore, a method for devising the shape of the friction pad base is already known.

  Specifically, as shown in FIG. 10A, the friction pad receiving base 303 is provided with a contact portion 303b on the opposite side of the friction pad receiving base 303 from the side where the paper feed roller 30a is provided. Therefore, when the friction pad base 303 moves in a direction away from the paper feed roller 30a, the contact portion 303b contacts the structure body 305 and does not move beyond a certain amount of movement.

  However, in consideration of variations in the shape and assembly of parts such as the sheet feeding roller 30a and the structure 305, the contact portion 303b and the structure 305 may interfere with each other, and the gap L cannot be set small. As a result, the gap L is set to be large in consideration of variation, and the friction pad receiving base 303 is pushed down in the direction away from the paper feed roller 30a, and the friction pad 302, the paper feed roller 30a, and the sheet It is not possible to generate an appropriate frictional force. For this reason, after all, the problems of the occurrence of double feed, the problem of carry jam, and the problem of non-feed are not solved.

  On the other hand, as shown in FIG. 10B, a method of bringing the stopper pin 306 provided on the structure 305 into contact with the contact portion 303b is already known (Patent Document 1). According to the sheet feeding device having the stopper pin 306, the gap L between the friction pad receiving base 303 and the structure 305 can be adjusted by the amount of insertion of the stopper pin 306. For this reason, when the gap L between the friction pad receiving base 303 and the structure 305 varies due to variations in the shape or assembly of parts such as the paper feed roller 30a and the structure 305, an operator may use a tool such as a screwdriver. The gap L can be adjusted by adjusting the insertion amount of the stopper pin 306 by using it. The gap L can be set to a desired value by accurately performing this adjustment. As a result, the friction pad cradle 303 is prevented from being pushed down, and it seems that the above-described problems of occurrence of double feeding, occurrence of accompanying jam, and problems of occurrence of non-feeding can be solved.

  However, it is necessary to secure a space for providing the stopper pin 306 in the structure and a work space for adjusting the stopper pin 306, leading to an increase in the size of the paper feeding device. Further, this operation requires skill of the worker, and the accuracy of adjustment varies depending on the skill level of the worker, and it is difficult to effectively remove the variation. For this reason, after all, the problems of the occurrence of double feeding, the problem of carrying jam, and the problem of non-feeding are not solved. In addition, when double feeding occurs, problems such as troublesome jam processing for the operator and waste of paper also occur.

  Therefore, there is a demand for an image forming apparatus that can solve problems such as occurrence of double feed, occurrence of carry-on jam, and occurrence of non-feed without depending on the skill level of an operator.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a paper feeding device and an image forming apparatus that can easily assemble a friction pad type paper feeding / separating device for preventing double feeding with a simple configuration.

In order to solve the above-described problem, a paper feeding device according to claim 1 of the present invention provides:
A feeding means for feeding paper;
Separating means for separating the paper fed by the feeding means;
First urging means for urging the separating means in a direction in which the separating means is pressed against the feeding means;
A sheet feeding apparatus comprising: a structural member that supports the first biasing unit;
A first movement preventing means comprising a first surface and a second surface inclined with respect to the first surface;
The first movement blocking means is inclined in a direction in which the second surface is separated from the first surface from the tip in the mounting direction of the first movement blocking means,
The first movement preventing means, in the attached state of the first movement preventing means, the first surface is in contact with the structure member, the second surface is in contact with the separation means,
The first movement preventing means is held so as to prevent the separation means from moving in the direction opposite to the pressing direction.

  According to the present invention, it is possible to provide a paper feeding device and an image forming apparatus that can easily assemble a friction pad type paper feeding / separating device that prevents double feeding with a simple configuration.

1 is a configuration diagram schematically showing an overall configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an enlarged view (FIG. 2A) showing an enlargement of a paper feed unit of the image forming apparatus shown in FIG. 1, and FIG. 2B is an enlarged view of a stopper member of the image forming apparatus shown in FIG. FIG. FIG. 2 is a side view illustrating a state in which a paper feeding unit of the image forming apparatus illustrated in FIG. 1 is enlarged and a stopper member is retracted. FIGS. 4A and 4B are explanatory diagrams illustrating a switching unit of the image forming apparatus illustrated in FIG. 1, in which FIG. 4A is a perspective view illustrating a state in which the holding is released by the switching unit, and FIG. It is a perspective view which shows the state which carried out. FIG. 2 is an explanatory diagram for explaining the operation of a stopper member of the image forming apparatus shown in FIG. 1. FIG. 2 is an explanatory diagram for explaining the operation of a stopper member of the image forming apparatus shown in FIG. 1. FIG. 2 is an explanatory diagram for explaining the operation of a stopper member of the image forming apparatus shown in FIG. 1. FIG. 8A is an enlarged side view showing the vicinity of a contact portion of an image forming apparatus according to a second embodiment of the present invention, and FIG. 8A is a side view for explaining a force relationship applied to a stopper member. (B)-(d) is a side view which shows the various aspects of 2nd Embodiment. FIG. 9A is an enlarged side view showing a paper feeding unit of a paper feeding device using a conventional friction pad system, FIG. 9A is a side view showing a normal use state, and FIG. 9B is a bundle. FIG. 6 is a side view showing a state in which the formed paper has entered a separation nip portion. FIG. 10A is an enlarged side view illustrating a sheet feeding unit of a sheet feeding apparatus using a conventional friction pad system, and FIG. 10A is a side view illustrating a sheet feeding apparatus of a type that includes a contact portion to prevent double feeding. FIG. 10B is a side view showing a sheet feeding device of a type in which a stopper pin that abuts against the abutting portion is provided to prevent double feeding.

  Hereinafter, an image forming apparatus according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram schematically illustrating the overall configuration of an image forming apparatus according to a first embodiment of the present invention.

  An image forming apparatus according to an embodiment of the present invention will be described as a laser printer 1 as an example.

  The image forming apparatus 1 includes four process units 1K, 1Y, 1M, and 1C. The process unit forms an image with the developer of each color of black (K), yellow (Y), magenta (M), and cyan (C) corresponding to the color separation component of the color image.

  Each process unit 1K, 1Y, 1M, 1C has the same configuration except that it has toner bottles 6K, 6Y, 6M, 6C containing unused toners of different colors, and therefore, one process unit 1K. The other process units 1Y, 1M, and 1C will not be described below.

  The process unit 1K includes an image carrier 2K (for example, a photosensitive drum), a drum cleaning device 3K, a static eliminator (not shown), a charging device 4K, a developing device 5K, and the like. The process unit 1K is detachably attached to the main body of the image forming apparatus 1 so that consumable parts can be replaced at the same time.

  The exposure unit 7 is disposed above the process units 1K, 1Y, 1M, and 1C installed in the image forming apparatus 1. The exposure unit 7 is configured to emit laser light from the laser diode based on the image data.

The transfer device 15 is disposed below the process units 1K, 1Y, 1M, and 1C installed in the image forming apparatus 1.
The primary transfer rollers 19K, 19Y, 19M, and 19C are disposed in contact with the intermediate transfer belt 16 so as to face the image carriers 2K, 2Y, 2M, and 2C.
The intermediate transfer belt 16 is looped over the primary transfer rollers 19K, 19Y, 19M, and 19C, the driving roller 18, and the driven roller 17 so as to circulate.

  The secondary transfer roller 20 is disposed so as to face the driving roller 18 and contact the intermediate transfer belt 16. If the image carriers 2K, 2Y, 2M, and 2C are the first image carriers of the respective colors, the intermediate transfer belt 16 is a second image carrier that combines these images.

  The belt cleaning device 21 is installed on the downstream side of the secondary transfer roller 20 in the traveling direction of the intermediate transfer belt 16. Here, a cleaning backup roller (not shown) is provided on the side opposite to the belt cleaning device 21 with respect to the intermediate transfer belt 16.

  The sheet feeding tray 30 is installed below the image forming apparatus 1 and can accommodate a large number of sheets P. The paper feed tray 30 can be attached to and detached from the main body of the image forming apparatus 1 in order to replenish paper.

  The paper feed roller 30 a is provided above the paper feed tray 30 installed in the image forming apparatus 1 and feeds the paper P from the paper feed tray 30 toward the paper feed path 31. Further, a friction pad (not shown), a friction pad receiving base (not shown), a first biasing means (not shown), and a structure (not shown) which will be described later are provided in the vicinity of the paper feed roller 30a. It is equipped.

  The timing roller pair 14 is disposed immediately upstream of the secondary transfer roller 20 with respect to the intermediate transfer belt 16 and can temporarily stop the paper P fed from the paper feed tray 30. Then, the paper P once stopped by the timing roller pair 14 forms a slack. Then, the sheet P on which the slack is formed is sent to the secondary transfer nip portion between the secondary transfer roller 20 and the driving roller 18 in accordance with the timing at which the toner image formed on the intermediate transfer belt 16 is suitably transferred. . Then, the fed paper P is configured such that the toner image formed on the intermediate transfer belt 16 at the secondary transfer nip portion is transferred to a desired transfer position with high accuracy.

The post-transfer conveyance path 33 is disposed above the secondary transfer nip portion between the secondary transfer roller 20 and the drive roller 18.
The fixing device 34 is installed in the vicinity of the upper end of the post-transfer conveyance path 33. The fixing device 34 includes a fixing roller 34a containing a heat source such as a halogen lamp (not shown), and a pressure roller 34b that rotates while contacting the fixing roller 34a with a predetermined pressure.

The post-fixing conveyance path 35 is disposed above the fixing device 34 and branches into a paper discharge path 36 and a reverse conveyance path 41 at the upper end of the post-fixing conveyance path 35.
The switching member 42 is disposed at the branch portion and is driven to swing around the swing shaft 42a.
The paper discharge roller pair 37 is disposed in the vicinity of the opening end of the paper discharge path 36.
The reverse conveying path 41 merges with the sheet feeding path 31 at the other end with the branch portion. A reverse conveyance roller pair 43 is disposed in the middle of the reverse conveyance path 41.

The paper discharge tray 44 is installed on the upper part of the image forming apparatus 1 so as to form a concave shape inward of the image forming apparatus 1.
The powder container 10 (for example, a toner container) is disposed between the transfer device 15 and the paper feed tray 30. The powder container 10 is detachably attached to the main body of the image forming apparatus 1.

  The image forming apparatus 1 of the present embodiment requires a predetermined distance from the paper feed roller 30a to the secondary transfer roller 20 due to transfer paper conveyance. The powder container 10 is installed in the dead space generated at this distance to reduce the size of the entire image forming apparatus.

  The transfer cover 8 is installed above the paper feed tray 30 and in front of the paper feed tray in the drawing direction. The inside of the image forming apparatus 1 can be inspected by opening the transfer cover 8.

  Although the image forming apparatus according to the embodiment of the present invention describes a laser printer, the present invention is not limited to this form, and any one of a copying machine, a facsimile, a printer, a printing machine, and an inkjet recording apparatus, Alternatively, the present invention can be applied to an image forming apparatus in which at least two of these are combined.

  Next, the basic operation of the image forming apparatus according to the present embodiment will be described below with reference to FIG. First, the case of performing single-sided printing will be described. As shown in FIG. 1, the paper feed roller 30 a rotates in response to a paper feed signal from a control unit (not shown) of the image forming apparatus 1. Then, the paper feed roller 30 a separates only the uppermost paper P of the paper P stacked on the paper feed tray 30 and sends it to the paper feed path 31. When the leading edge of the paper P delivered by the paper supply roller 30a reaches the secondary transfer nip portion of the timing roller pair 14, it forms a slack and waits in that state. Then, the optimum timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to this sheet is achieved, and the leading edge skew of the sheet P is corrected.

  Here, regarding the image forming operation, one process unit 1K will be described, and description of the other process units 1Y, 1M, and 1C will be omitted. First, the charging device 4K uniformly charges the surface of the image carrier 2K to a high potential. The exposure device 7 irradiates the surface of the image carrier 2K with a laser beam L based on the image data. Then, on the surface of the image carrier 2K irradiated with the laser beam L, the potential of the irradiated portion is lowered to form an electrostatic latent image.

  Then, the developing device 5K transfers the unused black toner supplied from the toner bottle 6K to the surface portion of the image carrier 2K on which the electrostatic latent image is formed. The image carrier 2K to which the toner has been transferred forms (develops) a black toner image on the surface thereof. Then, the toner image formed on the image carrier 2K is transferred to the intermediate transfer belt 16.

  The drum cleaning device 3K removes residual toner adhering to the surface of the image carrier 2K after the intermediate transfer process. The removed residual toner is sent to a waste toner container (not shown) in the process unit 1K and collected by a waste toner conveying means (not shown). Further, the neutralization device (not shown) neutralizes the residual charge of the image carrier 2K from which the residual toner has been removed by the cleaning device 3K.

  In the process units 1Y, 1M, and 1C for the respective colors, toner images are similarly formed on the image carriers 2Y, 2M, and 2C, and transferred to the intermediate transfer belt 16 so that the respective color toner images are overlapped.

  When the intermediate transfer belt 16 having the toner images transferred so as to overlap each other travels to the secondary transfer nip portion of the secondary transfer roller 20 and the drive roller 18, the toner image on the intermediate transfer belt 16 is transferred to the timing roller pair 14 as shown in FIG. The image is transferred to the paper P sent out by. Here, the paper P is sent out to the secondary transfer nip portion in accordance with the timing at which the toner image formed by being superimposed and transferred onto the intermediate transfer belt 16 is suitably transferred. Then, on the fed paper P, the toner image formed on the intermediate transfer belt 16 at the secondary transfer nip portion is transferred to a desired transfer position with high accuracy.

  The paper P on which the toner image has been transferred is conveyed to the fixing device 34 through the post-transfer conveyance path 33. The sheet P conveyed to the fixing device 34 is sandwiched between the fixing roller 34a and the pressure roller 34b, and the unfixed toner image is fixed by heating and pressing. The sheet P on which the toner image is fixed is sent out from the fixing device 34 to the post-fixing conveyance path 35.

  The switching member 42 is in a position where the vicinity of the upper end of the post-fixing conveyance path 35 is opened as shown by the solid line in FIG. 1 at the timing when the paper P is sent out from the fixing device 34. The paper P sent out from the fixing device 34 is sent out to the paper discharge path 36 via the post-fixing conveyance path 35. The paper discharge roller pair 37 sandwiches the paper P sent to the paper discharge path 36 and rotates to discharge the paper P to the paper discharge tray 44, thereby completing single-sided printing.

  Next, a case where duplex printing is performed will be described. As in the case of single-sided printing, the fixing device 34 sends the paper P to the paper discharge path 36. When performing duplex printing, the paper discharge roller pair 37 conveys a part of the paper P to the outside of the image forming apparatus by rotational driving. When the rear end of the paper P passes through the paper discharge path 36, the switching member 42 swings about the swing shaft 42a as shown by the dotted line in FIG. 1 and closes the upper end of the post-fixing transport path 35. To do. Then, almost simultaneously with the closing of the upper end of the post-fixing conveyance path 35, the paper discharge roller pair 37 rotates in the direction opposite to the direction in which the paper P is conveyed to the outside of the image forming apparatus and is sent to the reverse conveyance path 41.

  The sheet P sent to the reverse conveyance path 41 reaches the timing roller pair 14 through the reverse conveyance roller pair 43. Then, the timing roller pair 14 achieves the optimum timing (synchronization) for transferring the toner image formed on the intermediate transfer belt 16 to the toner image non-transfer surface of the paper P, and sends the paper P to the secondary transfer nip portion. .

  The secondary transfer roller 20 and the drive roller 18 transfer the toner image to the toner image non-transfer surface of the paper P when the paper passes through the secondary transfer nip portion. Then, the paper P on which the toner image has been transferred is conveyed to the fixing device 34 through the post-transfer conveyance path 33. The fixing device 34 fixes the unfixed toner image on the paper P by sandwiching the conveyed paper P between the fixing roller 34a and the pressure roller 34b and applying heat and pressure. Then, the paper P on which the toner image is fixed is sent out from the fixing device 34 to the post-fixing conveyance path 35.

  The switching member 42 is in a position where the vicinity of the upper end of the post-fixing conveyance path 35 is opened as shown by the solid line in FIG. 1 at the timing when the paper P is sent out from the fixing device 34. The paper P sent out from the fixing device 34 is sent out to the paper discharge path 36 via the fixing conveyance path. The paper discharge roller pair 37 sandwiches the paper P sent to the paper discharge path 36, rotates and discharges it to the paper discharge tray 44, thereby completing double-sided printing.

Further, after the toner image on the intermediate transfer belt 16 is transferred to the paper P, residual toner adheres on the intermediate transfer belt 16. Then, the belt cleaning device 21 removes the residual toner from the intermediate transfer belt 16.
The toner removed from the intermediate transfer belt 16 is transported to the powder container 10 by a waste toner transport unit (not shown) and collected in the powder container 10.

  Next, the configuration of the sheet feeding unit, which is a characteristic configuration of the image forming apparatus according to the present embodiment, will be described in detail below.

  As shown in FIG. 2A, the bottom plate 301 is provided inside a paper feed tray (not shown), and sheets P (not shown) are stacked on the bottom plate 301. And the raising / lowering means (not shown) raises / lowers the baseplate 301. FIG.

  A sheet feeding roller (an example of a feeding unit) 30a is configured by an elastic member having an outer periphery, and an image forming apparatus (not shown) whose both ends in the longitudinal direction face each other in the transfer belt running direction. It is rotatably supported by both side walls of the main body. The paper feed roller 30a is in contact with the uppermost paper P of the paper P stacked on the bottom plate and pressed downward with the paper feed tray mounted on the main body of the image forming apparatus.

  The friction pad base 303 (an example of a separating unit) 303 is configured to rotate around a rotation shaft 303a that is pivotally supported by the image forming apparatus main body in the vicinity of the downstream end in the sheet conveyance direction. A surface of the friction pad receiving base 303 opposite to the surface on which the friction pad 302 is installed has a contact portion 303b.

  The friction pad 302 is made of a material having elasticity, and is disposed in the vicinity of one end side of the friction pad receiving base 303 provided with the rotation shaft 303a so as to face the paper feed roller 30a. Then, when the friction pad receiving base 303 is rotated, the friction pad receiving base 303 comes into contact with the paper feed roller 30a.

  A separation spring (an example of a first urging unit) 304 is provided in a structural member (structure) 305 installed in the main body of the image forming apparatus, and the friction pad 302 is fed to the paper feed roller 30a via the friction pad base 303. It is supposed to be energized. When a plurality of sheets P are sent in a superimposed manner (multiple feeds), the plurality of sheets P are separated by a frictional force, and double feeding is prevented. Specifically, when the friction coefficient μr between the paper feed roller 30a and the paper P, the friction coefficient μp between the papers, and the friction coefficient μf between the paper P and the friction pad 302, the relationship between the friction coefficients is as follows. μr> μf> μp, and only the uppermost paper is separated and fed due to the difference in frictional force.

  The stopper member (first movement blocking means) 307 has a substantially wedge shape having a first surface in contact with the structure 305 and a second surface in contact with the contact portion 303b and inclined with respect to the first surface. The stopper member 307 is provided between the contact portion 303b and the structure body 305, and thereby absorbs the variation in the gap L due to the variation in components and the like.

  When the variation amount of the gap L is set to ± δ, as shown in FIG. 2B, the difference in length of the side connected to the hypotenuse on the side surface perpendicular to the longitudinal direction of the stopper member 307 (hereinafter referred to as “slope surface”). A) is preferably a> 2δ.

  The urging means (second urging means) 308 urges the stopper member 307 in a direction to enter the gap between the abutting portion 303b and the structure 305, as shown in FIG. The friction pad cradle 303 is prevented from moving in a direction away from the paper feed roller 30a because the contact portion 303b contacts the stopper member 307.

  Further, as shown in FIG. 3, the switching unit 310 holds the stopper member 307 in a second state where the contact portion 303b does not contact the stopper member 307, or releases the holding and the contact portion 303b stops the stopper member 307. The first state can be brought into contact with the member 307. Therefore, when using sheets that are easy to double feed, the holding of the stopper member 307 is released by the switching means 310, the contact portion 303b is brought into contact with the stopper member 307, and the friction pad receiving base 303 is pushed down. Blocking by 307 can prevent double feeding. On the other hand, when using paper that does not cause the risk of double feeding, the stopper member 307 is held by the switching unit 310, and the stopper member 307 does not prevent the friction pad base 303 from being pushed down.

  Specifically, as shown in FIG. 4A, the stopper member 307 is provided with an elastic deformation portion 307a (310), and the guide portion 305a (310) formed in the structure 305 that guides the movement of the stopper member 307. The fitting part 305b (310) is provided in a part of the.

  And the elastic deformation part 307a is fitted to the fitting part 305b, as shown in FIG.4 (b). As a result, as shown in FIG. 3, the stopper member 307 is held at a position in the second state that does not prevent the friction pad receiving base 303 from being pushed down.

  Therefore, the image forming apparatus can generate an appropriate frictional force on the paper corresponding to a wide variety of paper types. In the present embodiment, the switching unit 310 employs a fitting method based on a claw structure using the elastic force of the resin, but is not limited to this mode, and a method of providing a hook portion on the stopper member 307 and the structure 305, Another part with a locking mechanism may be added. In addition, although the friction pad cradle 303 is rotated by using the rotation shaft 303a as a fulcrum, the present invention is not limited to this mode and can be implemented by a direct acting friction pad configuration. Further, although the friction pad 302 and the structure 305 have been described as being provided in the image forming apparatus main body, the invention is not limited to this aspect, and may be provided in a paper feed tray or the like.

  Next, a specific operation of the stopper member, which is a characteristic configuration of the image forming apparatus according to the present embodiment, will be described with reference to the drawings. For convenience of explanation, illustration of the biasing means 308 is omitted.

  First, the case where the image forming apparatus is manufactured in a state where the gap between the contact portion 303b and the structure 305 is larger than the design value will be described. When an image forming apparatus of L + δ in which the gap between the contact portion 303b and the structural body 305 is larger than the design value L due to variations in parts and the like is manufactured, the stopper member 307 is provided with an urging means (see FIG. 5). The second surface of the stopper member 307 contacts the contact portion 303b at a position away from the first surface.

  The pressing force between the friction pad 302 and the paper feed roller 30a is kept substantially constant regardless of the variation of each component. For this reason, even when a plurality of sheets are fed, an appropriate frictional force can be generated among the friction pad 302, the sheet feeding roller 30a, and the sheets, and the separation performance can be stabilized and double feeding can be prevented. .

  Next, a case where the image forming apparatus is manufactured in a state where the gap between the contact portion 303b and the structure 305 is smaller than the design value will be described. When an image forming apparatus having an L-δ in which the gap between the contact portion 303b and the structure 305 is smaller than the design value L due to variations in parts or the like is manufactured, the stopper member 307 includes an urging unit as shown in FIG. (Not shown), and the second surface of the stopper member 307 contacts the contact portion 303b at a position approaching the first surface. In this case, the pushing amount of the stopper member 307 is smaller than the pushing amount of the stopper member 307 when the image forming apparatus is manufactured with the gap between the contact portion 303b and the structure 305 being L + δ which is larger than the design value.

  The pressing force between the friction pad 302 and the paper feed roller 30a is kept substantially constant regardless of the variation of each component. For this reason, even when a plurality of sheets are fed, an appropriate frictional force can be generated among the friction pad 302, the sheet feeding roller 30a, and the sheets, and the separation performance can be stabilized and double feeding can be prevented. .

  Next, a case where the gap between the contact portion 303b and the structure 305 is manufactured as designed will be described. When an image forming apparatus having a design value L between the contact portion 303b and the structure 305 is manufactured, the stopper member 307 is pushed by an urging means (not shown) as shown in FIG. The second surface of the member 307 contacts the contact portion 303b at a position between the position away from the first surface and the approached position. The pushing amount of the stopper member 307 in this case is smaller than the pushing amount of the stopper member 307 when the image forming apparatus is manufactured with the gap between the contact portion 303b and the structure 305 being L + δ which is larger than the design value. The gap between the portion 303b and the structure 305 is larger than the pushing amount of the stopper member 307 when the image forming apparatus is manufactured with L-δ which is smaller than the design value.

  The pressing force between the friction pad 302 and the paper feed roller 30a is kept substantially constant regardless of the variation of each component. For this reason, even when a plurality of sheets are fed, an appropriate frictional force can be generated among the friction pad 302, the sheet feeding roller 30a, and the sheets, and the separation performance can be stabilized and double feeding can be prevented. .

  On the other hand, when using paper that does not cause the risk of double feeding, the stopper member 307 is held by the switching unit 310, and the stopper member 307 does not prevent the friction pad base 303 from being pushed down. Therefore, the image forming apparatus can generate an appropriate frictional force on the paper corresponding to a wide variety of paper types.

  Next, the operation of the image forming apparatus according to this embodiment will be described.

  The stopper member 307 has a substantially wedge shape in which the second surface is inclined in a direction away from the first surface from the tip in the mounting direction. Therefore, the operator can easily attach the first surface to the structure body 305 and the second surface to contact the contact portion 303b without depending on the skill level. Further, after the stopper member 307 is attached, the stopper member 307 is held so that the friction pad receiving base 303 is prevented from moving in a direction away from the paper feed roller 30a. For this reason, the pressing force between the friction pad 302 and the paper feed roller 30a is kept substantially constant without being affected by variations of each component. As a result, even when a plurality of sheets are fed, an appropriate frictional force can be generated among the friction pad 302, the sheet feeding roller 30a, and the sheets, thereby stabilizing the separation performance and preventing double feeding. it can.

  Further, since the stopper member 307 is biased by the second biasing means 308 such as a spring, it is not necessary for the operator to adjust the stopper member 307 by operating the stopper member 307. It can be adjusted by the member 307. Therefore, the movement of the friction pad cradle 303 can be automatically regulated to prevent double feeding without being affected by variations in the parts of the apparatus. Further, it is not necessary to secure a work space for adjusting the stopper member 307 by the operator, and the apparatus can be downsized.

  Further, the image forming apparatus 1 according to the present embodiment includes a switching unit 310 that can switch between a first state in which the stopper member 307 contacts the contact portion 303b and a second state in which the stopper member 307 does not contact the contact portion 303b. I have. For this reason, when using paper that is likely to be double-fed, the switching unit 310 can switch to the first state in which the stopper member 307 is not held and prevent double-fed. On the other hand, when using paper that does not cause the risk of double feeding, the stopper member 307 is held by the switching unit 310, and the stopper member 307 does not prevent the friction pad base 303 from being pushed down. For this reason, the image forming apparatus 1 can adjust the pressure applied to the separation nip portion, can cope with a wide variety of paper types, and eliminates the problem of non-feeding.

  Next, a sheet feeding device of various modes according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the structure equivalent to 1st Embodiment mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. For convenience of explanation, FIG. 5 shows the stopper member 307 and the structural body 305 that are actually in contact with each other in a non-contact state.

  FIG. 8A is an explanatory diagram for explaining the force acting on the stopper member 307. Of the force received by the stopper member 307 from the contact portion 303b, the component force of the component parallel to the biasing direction of the biasing means 308 is Fh, and the component force of the component orthogonal to the biasing direction of the biasing means 308 is Fv. The pressure applied by the biasing means 308 is Fsp. Further, when the friction coefficient between the stopper member 307 and the structure 305 is μ, a frictional force μFv is generated in a direction that prevents the movement of the stopper member 307 by Fh.

  In order to separate the overlapped sheets, it is necessary to generate an appropriate frictional force among the friction pad 302, the sheet feeding roller 30a, and the sheet. Therefore, it is necessary to prevent the stopper member 307 from moving in the direction opposite to the direction urged by the urging means 308, and the condition is Fsp + μFv> Fh. Further, it is necessary to prevent a pressing force exceeding a predetermined pressing force, and the condition is Fsp ≦ Fh.

  Therefore, in order to prevent the stopper member 307 from moving in the direction opposite to the direction urged by the urging means 308, the adjustment of the urging force Fsp of the urging means 308 and between the stopper member 307 and the structure 305 are performed. It is necessary to manage the friction coefficient μ and adjust the balance between the force components Fh and Fv of the force received by the stopper member 307 from the contact portion 303b.

  The image forming apparatus according to the present embodiment can easily adjust Fh and Fv by adjusting the inclination angle of the substantially wedge shape of the stopper member 307.

  In general, the stopper member 307 is made of resin, and the structure 305 is made of resin or metal. For this reason, the friction coefficient between resin products or the friction coefficient between resin products and metal products is small and difficult to manage.

Therefore, as shown in FIG. 8B, the frictional force μ ₁ generated between the stopper member 307 and the friction member 309 is provided by providing the structure 305 with a friction member (second movement prevention means) 309 having a large friction coefficient. Fv can be increased. Therefore, even when Fh is increased by pressing from the contact portion 303b, it is possible to satisfy Fsp + μ ₁ Fv> Fh and to prevent the stopper member 307 from being pushed back. Needless to say, the friction member 309 may be provided on the stopper member 307 instead of providing the friction member 309 on the structure 305.

In addition, as shown in FIG. 8C, instead of providing the friction member 309, a so-called latch shape (second movement preventing means) in which the stopper member 307 and the structure 305 are engaged with each other is formed as a stopper member 307. Each of the structures 305 may be provided. As a result, the stopper member 307 is easily mounted in the mounting direction with almost no resistance due to the latch shape (rack shape). On the other hand, after the stopper member 307 is attached, the stopper member 307 receives resistance due to the latch shape in a direction that prevents the friction pad receiving base 303 from moving in a direction away from the paper feed roller 30a. Therefore, the frictional force μ ₂ Fv between the latch shape 307b of the stopper member 307 and the latch shape 305c of the structure 305 can be increased. As a result, even when Fh is increased by pressing from the contact portion 303b, it is possible to satisfy Fsp + μ ₂ Fv> Fh and to prevent the stopper member 307 from being pushed back.

Further, as shown in FIG. 8D, the stopper member 307 may be provided with a latch shape 307b, and the structure body 305 may be provided with a friction member 309. As a result, the frictional force μ ₃ Fv generated between the latch shape 307b of the stopper member 307 and the friction member 309 can be increased. Therefore, even when Fh is increased by pressing from the contact portion 303b, it is possible to satisfy Fsp + μ ₃ Fv> Fh and to prevent the stopper member 307 from being pushed back. Needless to say, the stopper member 307 may be provided with the friction member 309 and the structure 305 may be provided with the latch shape 305c.

  Next, the operation of the image forming apparatus according to the second embodiment will be described.

  The image forming apparatus according to the second embodiment is provided with a friction member 309 and a latch shape for preventing the stopper member 307 from being pushed back, in addition to the biasing means 308, so that the contact is made in addition to the action of the first embodiment. The stopper member 307 can be reliably slipped in the direction opposite to the direction in which the portion 303b and the structure 305 are inserted. Therefore, a plurality of sheets are conveyed to the nip portion between the friction pad 302 and the paper feed roller 30a, and the friction pad receiving base 303 tries to move away from the paper feed roller 30a, and a large force is applied to the contact portion 303b. Even in this case, the stopper member 307 does not move in the direction opposite to the direction in which the stopper member 307 enters between the contact portion 303b and the structure body 305. As a result, it is possible to reliably prevent double feeding.

  In addition, since at least one of the structure body 305 and the stopper member 307 is provided with a latch shape, the stopper member 307 moves in a direction opposite to the direction in which the stopper member 307 enters between the contact portion 303b and the structure body 305. There is no. As a result, it is possible to reliably prevent double feeding.

  In addition, according to the image forming apparatus using the paper feeding device according to any one of claims 1 to 7, the friction pad type paper feeding / separating device for preventing double feeding can be easily assembled with a simple configuration. An image forming apparatus can be provided and provided.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this. The image forming apparatus according to the embodiment of the present invention describes a laser printer. However, the image forming apparatus is not limited to this form, and any one of a copying machine, a facsimile, a printer, a printing machine, and an inkjet recording apparatus, Alternatively, the present invention can be applied to an image forming apparatus in which at least two of these are combined.

  It should be noted that the materials and dimensions of each component introduced in the above-described embodiment are merely examples, and it is needless to say that various materials and dimensions can be selected within a range where the effects of the present invention can be exhibited.

1 Laser printer (an example of an image forming device)
30a Paper feeding roller (an example of feeding means)
301 Bottom plate 302 Friction pad (an example of separation means)
303 Friction pad cradle (an example of separating means)
303a Rotating shaft 303b Abutting portion 304 Separation spring (an example of first urging means)
305 Structure (structure member)
307 Stopper member (first movement prevention means)
310 switching means 305a (310) guide section (an example of switching means)
305b (310) Fitting portion (an example of switching means)
307a (310) Elastic deformation part (an example of switching means)
308 Energizing means (second energizing means)
309 Friction member (an example of second movement preventing means)
307b Latch shape (an example of second movement blocking means)
305c Latch shape (an example of second movement blocking means)

JP-A-10-279105 No. 4-2911 JP 2000-335768 A

Claims (8)

A feeding means for feeding paper;
Separating means for separating the paper fed by the feeding means;
First urging means for urging the separating means in a direction in which the separating means is pressed against the feeding means;
A sheet feeding apparatus comprising: a structural member that supports the first biasing unit;
A first movement preventing means comprising a first surface and a second surface inclined with respect to the first surface;
The first movement blocking means is inclined in a direction in which the second surface is separated from the first surface from the tip in the mounting direction of the first movement blocking means,
The first movement preventing means, in the attached state of the first movement preventing means, the first surface is in contact with the structure member, the second surface is in contact with the separation means,
The sheet feeding device, wherein the first movement preventing unit is held so as to prevent the separation unit from moving in a direction opposite to the pressing direction.   The sheet feeding device according to claim 1, wherein the separation unit includes a contact portion that contacts the second surface. The mounting direction is a direction that enters between the separating member and the structural member substantially parallel to the first surface,
3. The sheet feeding device according to claim 1, wherein the first movement prevention unit includes a second urging unit that urges the first movement prevention unit in the attachment direction. 4.   The first movement preventing means includes switching means capable of switching between a first state in which the second surface is in contact with the separation means and a second state in which the second surface is not in contact with the separation means. The sheet feeding device according to any one of claims 1 to 3.   The first movement preventing means is provided in the direction opposite to the pressing direction by the second movement preventing means provided on at least one of the first surface and the structural member in contact with the first surface. The sheet feeding device according to claim 1, wherein the sheet feeding device is slipped so as to prevent movement of the separating unit.   The sheet feeding device according to claim 5, wherein the second movement preventing unit is a friction member.   The sheet feeding device according to claim 5, wherein the second movement preventing unit has a latch shape provided on at least one of the structural member and the second surface.   An image forming apparatus comprising the paper feeding device according to claim 1.

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