JP2007161448A - Sheet feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate a work burden to a user by lightly taking in and out even a sheet cassette having a large sheet loading quantity and having large weight in a sheet feeder. <P>SOLUTION: When the user rotates an operation lever 102 by being pulled to this side from a state of extracting the sheet cassette 32, its movement is transmitted to the passive surface 105c of a spring switching arm 105 on the device body side. When the spring switching arm 105 rotates clockwise, a coil spring 106 is displaced by extending. An extraction arm 104 rotates counterclockwise by receiving rotational torque by its extended coil spring 106, and its rotational movement is transmitted to a transmission arm 101 on the sheet cassette 32 side. The sheet cassette 32 is doubled in force in the direction pulled in a device body of the sheet feeder 31 via the transmission arm 101. To the contrary, even if extracting the sheet cassette 32 of an installed state from the sheet feeder 31, an extraction force is doubled by rotational torque switched in the inverse direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus provided in an image forming apparatus such as a printer, a copying machine, a facsimile machine, and a multifunction machine.

  In an image forming apparatus having a structure in which a sheet cassette loaded with recording paper or the like is loaded into and removed from the image forming apparatus main body from one direction, the sheet cassette must always be accurately attached to and detached from a predetermined mounting position of the image forming apparatus main body. Is required. By mounting the sheet cassette in the proper mounting position, the image position on the sheet formed by the image forming unit is accurately determined, and it does not cause a conveyance failure such as a paper jam (jam) during the conveyance. Stable sheet conveyance becomes possible. At the same time, with regard to the attachment / detachment operation of the sheet cassette to / from the image forming apparatus main body that is frequently performed every time the sheet is replenished, simple convenience that does not cause the user to apply a great force is required.

  A cassette holding device using a toggle mechanism has been proposed for the purpose of accurately mounting the sheet cassette to the image forming apparatus main body and reducing labor at the time of attachment / detachment (see, for example, Patent Document 1). In the cassette holding device using the toggle mechanism, when the cassette is inserted, when the sheet cassette is inserted to a predetermined position, the toggle cassette automatically pulls the sheet cassette into the mounting position in the image forming apparatus main body using a spring force. Is positioned. On the other hand, when pulling out the sheet cassette, if the sheet cassette is pulled out to a predetermined position against the spring force, the toggle mechanism automatically pushes the fixed amount by the spring force.

JP-A-4-85220

  By the way, in the sheet cassette for the large capacity sheet feeding apparatus, the total weight including the sheet cassette when the sheets are fully loaded may exceed, for example, 30 kg. In order to insert and remove such a heavy sheet cassette into and from the image forming apparatus main body, it is difficult to cope with a cassette holding apparatus using a toggle mechanism, which imposes great effort on the user. That is, a large spring force is required to pull in a heavy sheet cassette. However, when pulling out the sheet cassette, the sheet cassette must be pulled out against the large spring force, which is a heavy burden on the user.

  In view of the above, an object of the present invention is to provide a sheet feeding apparatus that can be easily put in and out even in the case of a sheet cassette having a large sheet stacking capacity and a large weight, and can reduce the work burden on the user.

  In order to achieve the above object, in the sheet feeding apparatus according to the present invention, a sheet cassette for stacking and storing sheets is provided so as to be freely inserted into and removed from the apparatus main body, and the rotation of the toggle mechanism is used to rotate the sheet cassette. In the sheet feeding apparatus having a mechanism for assisting in and out of the apparatus main body, an operation force reducing mechanism for reducing an operation force at the time of switching the urging direction in the toggle mechanism is provided. .

  According to the sheet feeding device of the present invention, the operation force reducing mechanism can reduce the labor when the sheet cassette is taken in and out of the apparatus main body, and is particularly effective when a large amount of sheets are loaded on the sheet cassette. is there.

  Hereinafter, preferred embodiments of a sheet feeding apparatus and an image forming apparatus according to the present invention will be described in detail with reference to the drawings in the case of an electrophotographic laser beam printer (hereinafter simply referred to as a printer).

(Image forming device)
First, a printer equipped with the sheet feeding apparatus of the present embodiment will be schematically shown with reference to FIGS. In this case, a large-capacity sheet feeding apparatus that stacks and stores a large amount of sheets S such as recording paper is assumed, and can be installed in the printer main body 1 as an option.

  The printer main body 1 whose appearance is shown in FIGS. 1 and 2 is equipped with sheet cassettes 2a and 2b in two upper and lower stages for storing sheets S of different sizes and quality as shown in FIG. 3 showing the internal structure. The printer main body 1 is taken in and out. When a sheet S having a size in the upper and lower sheet cassettes 2a and 2b is selected, it is picked up and sent out from the uppermost sheet S by the pickup rollers 3a and 3b. The sheets S sent out by the pickup rollers 3a and 3b are separated and conveyed one by one by the feed rollers 4a and 4b and the retard rollers 5a and 5b. Each of the pair of conveyance rollers 6, 7, 8, and 10 includes a pair of conveyance rollers 6, 7, and 10. The sheets S fed by the feed rollers 4 a and 4 b are sequentially received and conveyed toward the registration roller 11. With the registration roller 11 stopped, the leading edge of the sheet S conveyed by the conveyance roller 10 is brought into contact with the nip portion of the registration roller 11 to form a loop to correct skewing. The registration roller 11 conveys the sheet S to a nip portion between an electrophotographic photosensitive drum (hereinafter simply referred to as a photosensitive drum) 13 serving as an image forming unit built in the process cartridge 14 and the transfer roller 12. . The process cartridge 14 includes a photosensitive drum 13 and is combined with at least one of charging means, developing means, and cleaning means as process means to form a cartridge, which can be freely attached to and detached from the printer main body 1. Say things.

  The charging unit uniformly charges the drum surface of the photosensitive drum 13. An electrostatic latent image is formed by irradiating the charged surface of the photosensitive drum 13 with laser light corresponding to image information emitted from the laser exposure optical system 15, and a toner image is formed on the electrostatic latent image. Is done. That is, a toner image is formed on the photosensitive drum 13 by the developing means built in the process cartridge 14. The registration roller 11 rotates in synchronization with the rotation of the photosensitive drum 13. The registration roller 11 conveys the sheet S to the nip portion between the photosensitive drum 13 and the transfer roller 12, and the toner image on the drum surface is transferred by the action of the transfer roller 12. When the sheet S on which the toner image is transferred passes through the fixing device 16, the fixing device 16 is heated and pressurized to permanently fix the toner image on the sheet S. The sheet S that has been fixed is conveyed by a discharge roller 18 and discharged and stacked on a discharge tray 19 disposed at the top of the printer body 1.

(Sheet feeding device)
Next, with reference to FIG. 3, the sheet feeding device 31 of the present embodiment that is provided as an option in the printer main body 1 will be described with reference to FIGS. 4 to 6.

  The sheet feeding device 31 also serves as a support for supporting the printer main body 1 from below, and has a sheet cassette 32 that accommodates a larger amount of sheets S than the upper and lower two-stage sheet cassettes 2a and 2b in the printer main body 1. The paper is fed one by one toward the image forming unit. The sheet cassette 32 can be inserted into and removed from the main body of the sheet feeding device 31. Inside the sheet cassette 32, a sheet stacking table 37 for stacking a large number of sheets S is provided so as to be movable up and down. Further, travel rails 40 a and 40 b are horizontally provided on the left and right sides of the sheet cassette 32, and are supported by guide rails 39 a and 39 b provided on the left and right sides of the outer casing of the sheet feeding device 31. Guided by the guide rails 39a and 39b on both sides, the sheet cassette 32 is taken in and out of the sheet feeding device 31 from the front of the casing.

  Above the sheet stacking table 37, a pickup roller 33 for feeding the sheet S from the uppermost one is disposed, and a feed roller 34 and a retard roller for separating and feeding the sheets S fed by the pickup roller 33 one by one. 35 is provided. The sheet S separated and fed by the feed roller 34 and the retard roller 35 is conveyed toward the image forming unit of the printer main body 1 by the conveyance roller 36. Further, the pulling wires 41 a and 41 b secured to the sheet stacking table 37 are wound by the winding drum 38 that rotates by receiving the rotational power, and the sheet stacking table 37 is raised. The height position of the raised sheet stacking table 37 is detected by the detecting means 43, and the uppermost sheet S is controlled so as to be always at a constant height level. The sheet S fed to the image forming unit is discharged to the discharge tray 19 after completing the image formation through the image forming process.

  The sheet feeding device 31 is provided with an operation force reducing mechanism that is a main part of the present invention. This mechanism is a mechanism for improving the pull-in mechanism of the sheet cassette 32 using the principle of the toggle mechanism. A mechanism for pulling in the sheet cassette is generated when a pulling arm 104, which will be described later, switches its rotation direction (toggle mechanism) according to the positional relationship between the fulcrum position (the position of the fulcrum pin 105a) and the coil spring 106. It uses power. Next, the operating force reduction mechanism will be described.

  The casing of the sheet feeding device 31 has a curved guide groove 103 formed with a predetermined curvature that is engaged and guided by an engagement pin 101b of a transmission arm 101 provided in a sheet cassette 32 described later. is doing. The feeding device housing is provided with a retracting arm (retracting member) 104 and a spring switching arm (elastic switching member) 105 so as to be rotatable about fulcrum pins 104a and 105a, respectively. The pull-in arm 104 and the spring switching arm 105 are coupled to each other by hooking both ends of a coil spring (elastic member) 106 to spring locking portions 104b and 105b provided at one end, respectively. For this reason, the pulling arm 104 and the spring switching arm 105 are acted upon by the spring force of the coil spring 106, and both the arms operate so that the three points of the spring locking portions 104b and 105b and the fulcrum pin 105a are in a straight line (L1). Align on top. This straight line L1 serves as an action switching point when the sheet cassette 32 is pulled. When the fulcrum pin 104a is positioned on one side (inside the apparatus) with respect to the straight line L1 as the action switching point, a force acts in the direction of pulling out the sheet cassette 32 from the sheet feeding apparatus 31, and the other side (outside of the apparatus). ), A force acts in the direction in which the sheet cassette 32 is pulled into the sheet feeding device 31.

  On the other hand, on the sheet cassette 32 side, a transmission arm 101 and an operation lever (operation member) 102 are provided. The operation lever 102 can be rotated clockwise by a user pulling operation from a steady position in FIG. 4 with a fulcrum pin 102a provided in the vicinity of the upper end in the figure as a fulcrum. The end portion of the operation lever 102 adjacent to the fulcrum pin 102 a is a butting end portion 102 b, and the abutting end portion 102 b abuts against the passive surface 105 c at one end portion of the spring switching arm 105 when the lever is rotated. The spring switching arm 105 is rotated. The position of the fulcrum pin 102a of the operation lever 102 is greater than the distance from the abutting end portion 102b that contacts the passive surface 105c of the switching arm 105 with respect to the user's operation portion (lower end portion in the figure). Is set. Therefore, the switching arm 105 can be rotated with a large force by a smaller operation force based on the principle of the lever. One end of the transmission arm 101 is pivotally supported on the cassette housing via a fulcrum pin 101a, and a guide pin 101b provided on the other end engages with the curved guide groove 103 provided on the sheet feeding device 31 side. is doing. That is, the transmission arm 101 moves integrally with the loading / unloading operation of the sheet cassette 32, the guide pin 101b is guided in the guide groove 103, and the movement of the guide pin 101b is transmitted to the pull-in arm 104 engaged with one end thereof. To do.

  The operation force reducing mechanism configured as described above operates and acts as follows when the sheet cassette 32 is taken in and out of the sheet feeding device 31.

  First, as shown in FIG. 4, the sheet cassette 32 is pulled out from the sheet feeding device 31. At this time, the pull-in arm 104 and the spring switching arm 105 on the sheet feeding device 31 side are arranged so that the line connecting both the spring locking portions 104b and 105b and the fulcrum pin 105a is on a straight line (straight line L1). ing. At this time, since the fulcrum pin 104a is located on the inner side (right side in FIG. 4) with respect to the straight line L1, the retractable arm 104 tries to rotate by generating a rotational torque in the clockwise direction of the coil spring 106. However, it stops in contact with a stopper (not shown).

  From this state, when the user pushes the sheet cassette 32 into the sheet feeding device 31, a slight pushing movement of the sheet cassette 32 is transmitted to the drawing arm 104 of the sheet feeding device 31 via the transmission arm 101. . The guide pin 101b on one end side of the transmission arm 101 moves while being guided by the guide groove 103 on the sheet feeding device 31 side, and the pull-in arm 104 is pushed counterclockwise about the fulcrum pin 104a and rotates. . With this movement, the straight line L1 is displaced in the counterclockwise direction, and moves toward the inside of the sheet feeding device 31 on the right side in the drawing from the fulcrum pin 104a of the pull-in arm 104.

  As a result of this movement, the straight line L1, which is the action switching point, is positioned on the opposite side beyond the fulcrum pin 104a, whereby a rotational torque in the counterclockwise direction is generated in the retracting arm 104 by the elastic force of the coil spring 106. As a result, the retractable arm 104 is rotated counterclockwise around the fulcrum pin 104a. The rotational torque acting on the pulling arm 104 acts on the transmission arm 101 via the guide pin 101b, and is pulled from the transmission arm 101 to the sheet cassette 32 and transmitted as an urging force, and becomes a force for pulling into the sheet feeding apparatus 31. As shown in FIG. 5, the sheet cassette 32 pulled to the mounting position is stopped and positioned at a position where it abuts against a stopper (not shown). In the meantime, the user does not need to apply a large force to push in the sheet cassette 32, but only pushes in the sheet cassette 32 with a light force initially. Thereafter, the sheet cassette 32 is automatically moved toward the sheet feeding device 31 to the mounting position.

  On the other hand, when the user pulls out the sheet cassette 32 from the sheet feeding apparatus 31 for sheet replenishment or the like from the state in which the sheet cassette 32 is mounted and accommodated in the sheet feeding apparatus 31, the following operation is performed. As shown in FIG. 6, when the user grips the operation lever 102 and rotates the fulcrum pin 102a in the clockwise direction about the fulcrum pin 102a, the abutting end portion 102b of the lever end is the spring switching arm 105 on the sheet feeding device 31 side. Is pressed against the passive surface 105c. The spring switching arm 105 is rotated clockwise around the fulcrum pin 105a. At this time, the operation lever 102 rotates the switching arm 105 with a large force (a force against the elastic force of the coil spring 106) with a small operation force based on the principle of the lever. As the spring switching arm 105 rotates in the clockwise direction, the spring locking portion 105b approaches a line L2 connecting the spring locking portion 104b of the retracting arm 104. And the three points of the spring locking part 105b, the spring locking part 104b, and the fulcrum pin 104a are aligned on a straight line. This straight line L2 serves as an action switching point when the sheet cassette 32 is pulled out. In this state, no rotational torque is generated to rotate the retractable arm 104 by the coil spring 106. When the sheet cassette 32 is pulled out in this state, the pull-in arm 104 rotates in the clockwise direction, and the straight line L2, which is the action switching point, rotates in the clockwise direction. Thereby, the spring latching | locking part 105b of the switching arm 105 remove | deviates from on the straight line L2. As a result, the force of the coil spring 106 is switched so that the retractable arm 104 is rotated in the clockwise direction from the fulcrum 104a. The movement is transmitted as an urging force to the sheet cassette 32 via the transmission arm 101, and the sheet cassette 32 is automatically pulled out of the mounting position. In this manner, the user can pull out the sheet cassette 32 from the sheet feeding device 31 without applying a great force to the sheet cassette 32.

  By the way, in the conventional structure, the force for pulling out the sheet cassette becomes the force for pulling out the sheet cassette as it is, and particularly when the sheet stacking amount is large, a very large force is required. On the other hand, in the present embodiment, the sheet cassette 32 is added by the force generated from the operation force reducing mechanism, and both the pulling force and pulling force are negligible, and the user's work effort during loading / unloading of the cassette is reduced accordingly. .

  The present invention is not limited to the above-described embodiment, and other embodiments, application examples, modified examples, and combinations thereof are possible as long as they do not depart from the gist of the present invention.

  For example, in the above embodiment, as shown in FIG. 6, when the operation lever 102 is rotated, the spring locking portion 105b of the pull-in switching arm 105 is set to a position on the straight line L2. However, it is not limited to such a setting. The straight line L2 and the spring locking portion 105b of the switching arm 105 may be moved in the approaching direction and set to stop at or near the aligned position. That is, even if the spring locking portion 105b of the switching arm 105 is not aligned on the straight line L2, if the relative distance between the spring locking portion 105b and the straight line L2 is set to be small, the retraction arm 104 rotates counterclockwise. The rotational torque in the direction is reduced. As a result, the force for pulling out the sheet cassette 32 can be small. If the spring switching arm 105 is rotated so that the straight line L2 is on the left side of the spring locking portion 105b when the operation lever 102 is rotated, the pulling arm 104 is rotated in the clockwise direction. A rotating torque is generated. Therefore, a force is generated in the direction in which the sheet cassette 32 is pulled out, and the force for pulling out the sheet cassette 32 can be further reduced.

FIG. 3 is an external perspective view illustrating a state in which a large-capacity sheet feeding device according to the present embodiment is installed in a printer body. FIG. 3 is an external perspective view illustrating a state in which the sheet cassette is pulled out in the sheet feeding apparatus according to the embodiment. FIG. 3 is a cross-sectional view of a printer main body and a sheet feeding device. FIG. 4 is a diagram illustrating an operation force reducing mechanism when a sheet cassette is pulled out in the sheet feeding apparatus according to the embodiment. The figure which shows the state of the operation force reduction mechanism at the time of mounting | wearing of the sheet cassette. The figure which shows the state of the operation force reduction mechanism at the time of pulling out from the mounting of the sheet cassette.

Explanation of symbols

1 Printer body (image forming device body)
31 Sheet Feeder 32 Sheet Cassette 101 Transmission Arm 101a Supporting Pin 101b Guide Pin 102 Operation Lever 102a Supporting Pin 103 Guide Groove 104 Retraction Arm 104a Supporting Pin 104b Spring Locking Part 105 Spring Switching Arm 105a Supporting Pin 105b Spring Locking Part 105c Passive surface

Claims (7)

In a sheet feeding apparatus provided with a mechanism for assisting the loading and unloading of the apparatus main body of the sheet cassette using a rotational torque of a toggle mechanism, a sheet cassette for storing and storing sheets is provided so as to be freely inserted into and unloaded from the apparatus main body.
A sheet feeding apparatus comprising: an operation force reducing mechanism for reducing an operation force when the urging direction is switched in the toggle mechanism.   2. The sheet feeding according to claim 1, wherein the toggle mechanism generates a rotation torque for doubling a pulling-out force and a pushing-in force of the sheet cassette by switching at an action switching point. apparatus. The operating force reduction mechanism is
A retraction member that is pivotally supported by the apparatus main body and engages the sheet cassette to apply a pulling force and a pushing force;
An elastic switching member that is pivotally supported by the apparatus body and has a passive surface that receives an operating force at one end;
One end is locked in the vicinity of the operating end of the retracting member and the other end is locked to the elastic switching member, and when the elastic switching member is displaced, the pulling member is rotated by a tensile force. An elastic member that applies torque and switches the rotational torque in a cassette pull-out direction or a cassette push-in direction with the action switching point as a boundary;
An operation member that is pivotally supported by a rotation shaft so as to be rotatable by the sheet cassette, and that the other end abuts against the passive surface of the elastic switching member at the time of rotation and applies an operation force;
With
The sheet feeding apparatus according to claim 2, wherein the elastic switching member is rotated by an operation of the operation member so that the other end of the elastic member approaches the action switching point.   The operation portion is formed in a lever shape, and the distance between the operation end and the rotation shaft is the distance between the other end abutting the passive surface of the elastic switching member and the rotation shaft. The sheet feeding device according to claim 3, wherein the sheet feeding device is set to be longer.   The action switching point includes the rotation fulcrum at one end of the retracting member, the one end of the elastic member locked to the retracting member, and the elastic switching connected to the other end of the elastic member displaced. It is in a state of being aligned on a straight line connecting the three points with the other end of the member, and when the straight line is crossed to one side, the elastic member rotates the pulling member in the direction in which the sheet cassette is pulled out from the apparatus main body. The elastic member applies rotational torque to the pull-in member in a direction in which the sheet cassette is pushed into the apparatus main body when the sheet cassette is moved to the other side. The sheet feeding apparatus according to the description.   6. The elastic member according to claim 3, wherein the elastic member is a spring member including a coil spring having both ends locked to and connected to the drawing member and the elastic switching member. Sheet feeding device. The sheet feeding device according to any one of claims 1 to 6,
Image forming means for forming an image on a sheet fed from the sheet feeding device;
An image forming apparatus comprising:

Images