JP2024064231A - Paper feeder and image forming apparatus - Google Patents

Abstract

[Problem] Even if the recording sheets on the paper feed tray are misaligned, the recording sheets are reliably pulled out and transported. [Solution] In a paper feed device 20, an L-shaped frame 29 is rotated about an axis 28 to the upstream side in the pull-out direction of the recording sheets P on the paper feed tray 22 to move a pickup roller 23 to a position for pulling out the recording sheets P, and then the L-shaped frame 29 is rotated about an axis 28 to the downstream side in the pull-out direction to move a feed roller 24 to a transport position for the recording sheets P. At the pull-out position, the pickup roller 23 comes into contact with the topmost recording sheet P on the paper feed tray 22 and pulls out the recording sheets P. At the transport position, the feed roller 24 comes into contact with the pulled-out recording sheets P and transports the recording sheets P. [Selected Figure] Figure 2

Description

The present invention relates to a paper feeder that stacks and stores multiple sheets of paper on a paper tray and sequentially pulls each sheet from the paper tray to supply it, and to an image forming apparatus equipped with the same, and in particular to a technique for pulling sheets from the paper tray.

The image forming device includes a paper feeder that supplies recording paper and an image forming section that forms an image on the supplied recording paper. In the paper feeder, a paper feed tray on which multiple recording papers are stacked is raised, the topmost recording paper is pressed against a pickup roller, the pickup roller is rotated to pull out the topmost recording paper, and the pulled-out recording paper is transported and supplied by a feed roller.

For example, in the paper feeder described in Patent Document 1, the pickup roller is moved back and forth between an initial position where it is separated from the sheet and a pressure contact position where it is pressed against the sheet. The time A it takes for the pickup roller to move from the initial position to the pressure contact position and the time B from when the leading edge of the sheet is detected by a sensor on the feed roller side until the trailing edge of the sheet passes the separation position between the feed roller and the separation roller are calculated, and when the time (B-A) has elapsed since the leading edge of the sheet was detected by the sensor, the pickup roller is moved from the initial position to the pressure contact position. This narrows the sheet spacing, making it possible to increase the sheet transport speed.

In addition, in the paper feeder of the image forming apparatus described in Patent Document 2, a solenoid moves a swing gear toward or away from the drive system of the paper lifting means to lift or stop the paper in the tray. The same solenoid also swings the pickup roller via the swinging means to move the pickup roller toward or away from the paper in the tray. This links the paper lifting action by the paper lifting means and the paper feeding action by the pick-up roller, simplifying the mechanism that performs these actions.

In addition, in the sheet feeder described in Patent Document 3, the claw of the solenoid is separated from the claw portion of the control gear to start rotating the control gear, and this rotation of the control gear lowers the pickup roller to contact the paper and starts rotating the feed roller and pickup roller. When the paper is transported by the pickup roller to the downstream side of the feed roller in the paper transport direction, the pickup roller is raised and separated from the paper. This reduces the cost of the sheet feeder that performs the paper feeding operation.

JP 2001-146329 A Japanese Patent Application Laid-Open No. 07-215497 JP 2001-328732 A

As described above, in the paper feed device, the paper feed tray on which multiple sheets of recording paper are stacked is raised and the topmost sheet of recording paper is pressed against the pickup roller. However, this lifting action of the paper feed tray can shift the position of each sheet of recording paper on the paper feed tray, which can also shift the position of the topmost sheet of recording paper relative to the pickup roller, causing problems with the pickup roller's operation of pulling out the recording paper.

In Patent Document 1, the pickup roller reciprocates between an initial position where it is separated from the sheet and a pressure contact position where it is pressed against the sheet, but this cannot accommodate the above-mentioned misalignment of the recording sheets on the paper feed tray.

In addition, in Patent Document 2, a solenoid is used to link the paper lifting operation by the paper lifting means with the paper delivery operation by the pick-up roller, but this still cannot deal with the misalignment of the recording papers on the paper feed tray as described above.

Furthermore, in Patent Document 3, the pickup roller is lowered to contact the paper and the feed roller and pickup roller start to rotate, but like Patent Documents 1 and 2, this cannot deal with the misalignment of the recording papers on the paper feed tray as described above.

The present invention was developed in consideration of the above circumstances, and aims to make it possible to reliably pull out and transport recording paper even if the recording paper on the paper feed tray is misaligned.

A paper feeder according to one aspect of the present invention includes a paper tray on which multiple sheets of paper are stacked, a pickup roller that pulls out each of the sheets of paper one by one from the paper tray, a feed roller that transports the sheets of paper pulled out by the pickup roller, a support section that supports the pickup roller and supports the feed roller downstream of the pickup roller in the paper pull-out direction, an arm that is supported at one end so as to be rotatable around an axis provided below the paper tray toward the upstream and downstream sides of the paper pull-out direction and supports the support section at the other end away from the axis, and a front end supported by the support section that rotates the arm around the axis toward the upstream side of the paper pull-out direction. and a drive unit that moves the pickup roller to a pull-out position spaced upstream in the pull-out direction from the leading edge of each sheet of paper on the paper tray, and then rotates the arm downstream in the pull-out direction about the axis to move the feed roller supported by the support unit to a transport position downstream in the pull-out direction from the pull-out position. When the pickup roller is moved to the pull-out position, it comes into contact with the topmost sheet of paper among the sheets of paper on the paper tray and pulls out the topmost sheet, and when the feed roller is moved to the transport position, it comes into contact with the topmost sheet of paper pulled out by the pickup roller and transports the topmost sheet.

An image forming device according to one aspect of the present invention includes the paper feeder of the present invention described above and an image forming section that forms an image on the recording paper supplied from the paper feeder.

According to the present invention, even if the position of each recording paper on the paper feed tray is misaligned, the recording paper can be reliably pulled out and transported.

1 is a cross-sectional view showing an image forming apparatus to which a paper feeder according to a first embodiment of the present invention is applied; FIG. 2 is a cross-sectional view showing the paper feed device of the first embodiment. FIG. 2 is a plan view showing the inside of the paper feed device according to the first embodiment. 2 is a side view showing an L-shaped frame, a drive unit, a gear unit, and the like in the paper feeder of the first embodiment. FIG. 1A, 1B, and 1C are a side view showing the paper feeding device with each L-shaped frame rotated counterclockwise and the pick-up roller in contact with the feed roller, a side view showing the gear unit in the same state, and a plan view showing each roller and gear unit in the same state. 1A, 1B, and 1C are a side view showing the paper feeding device in a state where each L-shaped frame is rotated clockwise and the pick-up roller approaches the topmost sheet of recording paper on the paper feed tray, a side view showing the gear unit in the same state, and a plan view showing each roller and gear unit in the same state. 1A, 1B, and 1C are a side view showing the paper feeding device in a state where each L-shaped frame is rotated clockwise and the pick-up roller is in contact with the topmost layer of recording paper on the paper feed tray, a side view showing the gear unit in the same state, and a plan view showing each roller and gear unit in the same state. FIG. 2 is a block diagram showing an example of a control system of the paper feeder. 13A, 13B, and 13C are side views showing a paper feeder according to a second embodiment of the present invention, illustrating an operation procedure of the paper feeder. FIG. 11 is a plan view showing the inside of a paper feed device according to a second embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First Embodiment
1 is a cross-sectional view showing an image forming apparatus to which a paper feeder according to a first embodiment of the present invention is applied. As shown in FIG. 1, an image forming apparatus 10 of this embodiment includes an image reading unit 11 and an image forming unit 12.

The image reading unit 11 has an image sensor (CCD sensor, contact image sensor) that optically reads the image of the document, and the analog output of this image sensor is converted into a digital signal to generate image data representing the image of the document.

The image forming unit 12 prints an image represented by the image data on a recording sheet, and includes an image forming unit 3M for magenta, an image forming unit 3C for cyan, an image forming unit 3Y for yellow, and an image forming unit 3Bk for black. In each of the image forming units 3M, 3C, 3Y, and 3Bk, the surface of the photosensitive drum 4 is uniformly charged, the surface of the photosensitive drum 4 is exposed to light, an electrostatic latent image is formed on the surface of the photosensitive drum 4, the electrostatic latent image on the surface of the photosensitive drum 4 is developed into a toner image, and the toner image on the surface of the photosensitive drum 4 is transferred to the intermediate transfer belt 5. As a result, a color toner image is formed on the intermediate transfer belt 5. This color toner image is secondarily transferred to the recording sheet P transported from the paper feeder 20 through the transport path 8 in the nip area N between the intermediate transfer belt 5 and the secondary transfer roller 6.

After this, the recording paper P is heated and pressurized in the fixing unit 15 to fix the toner image on the recording paper P by thermocompression, and the recording paper P is then discharged to the paper discharge tray 17 via the discharge rollers 16.

Next, the paper feeder 20 of the first embodiment will be described. FIG. 2 is a cross-sectional view showing the paper feeder 20 of the first embodiment as seen from the side. FIG. 3 is a plan view showing the inside of the paper feeder 20 of the first embodiment.

As shown in Figures 2 and 3, the main body 21 of the paper feed device 20 is provided with a paper feed tray 22 on which multiple sheets of recording paper P are stacked, a pick-up roller 23 that pulls out the recording paper P from the paper feed tray 22, a feed roller 24 that transports the recording paper P, a retard roller 25 that contacts the underside of the periphery of the feed roller 24, a pair of pressure rollers 26 that press down each sheet of recording paper P on the paper feed tray 22, a lifting device 27 that raises and lowers the tip side of the paper feed tray 22, a pair of L-shaped frames 29 supported rotatably around an axis 28, and a drive unit 30 that rotates each L-shaped frame 29 clockwise and counterclockwise around the axis 28.

The transport roller 33 is not part of the paper feeder 20, but is provided on the main body side of the image forming device 10, and transports the recording paper P that is pulled out and supplied by the pick-up roller 23 and the feed roller 24 through the transport path 8 of the image forming device 10.

The rear end of the paper feed tray 22 is supported rotatably around shaft 22A, and the leading end of the paper feed tray 22 is raised and lowered by the lifting device 27. The lifting device 27 includes a lifting motor 35, a gear unit 36, and a lifting arm 37. The lifting motor 35 is driven to rotate, and this rotation is transmitted to the lifting arm 37 via the gear unit 36, causing the lifting arm 37 to rotate around its shaft 37A.

When the lift arm 37 rotates clockwise around its axis 37A, the tip of the lift arm 37 pushes up the paper feed tray 22, which then rotates clockwise around the axis 22A, causing the tip of the paper feed tray 22 to rise, and the topmost sheet of recording paper P on the paper feed tray 22 comes into contact with each pressure roller 26.

When the lift arm 37 rotates counterclockwise around its axis 37A, the paper feed tray 22 rotates counterclockwise around axis 22A under its own weight while following the tip of the lift arm 37, and the tip side of the paper feed tray 22 descends. This separates the paper feed tray 22 from each pressure roller 26, making it possible to load multiple sheets of recording paper P onto the paper feed tray 22.

The shaft 26A of each pressure roller 26 is rotatably supported by bearings 38 arranged on both outer sides of the paper feed tray 22 and fixed to the inside of the main body housing 21.

Each L-shaped frame 29 is disposed on either outer side of the paper feed tray 22. The shafts 28 that rotatably support each L-shaped frame 29 are provided below the paper feed tray 22 and are rotatably supported by respective bearings (not shown) fixed to the inside of the main body housing 21.

Each L-shaped frame 29 has an arm portion 41 supported so as to be freely rotatable around the axis 28, and a support portion 42 connected to the tip of the arm portion 41 away from the axis 28, and the arm portion 41 and the support portion 42 form an L shape.

The support portion 42 of each L-shaped frame 29 rotatably supports the shaft 23A of the pickup roller 23 and the shaft 24A of the feed roller 24.

A gear unit 50 is provided on the outside of the support portion 42 of one of the L-shaped frames 29. The gear unit 50 includes a first gear 51 fixed to the shaft 24A of the feed roller 24, a third gear 53 fixed to the shaft 23A of the pick-up roller 23, a second gear 52 provided between the first gear 51 and the third gear 53, and a driven pulley 55 fixed to the shaft 24A of the feed roller 24 and rotating with the first gear 51. The first gear 51 meshes with the second gear 52, and the second gear 52 meshes with the third gear 53. The shaft 52A of the second gear 52 is rotatably supported by the support portion 42 of each L-shaped frame 29, like the shaft 23A of the pick-up roller 23 and the shaft 24A of the feed roller 24.

Figure 4 is a side view showing the L-shaped frame 29, the drive unit 30, and the gear unit 50. As shown in Figure 4, a drive pulley 56 is rotatably provided on the shaft 28 that rotatably supports the arm portion 41 of the L-shaped frame 29, and a belt 57 is stretched between the drive pulley 56 and a driven pulley 55 fixed to the shaft 24A of the feed roller 24. The rotation of the motor is transmitted to the drive pulley 56 through gears (not shown) and the like, and in Figure 4, the drive pulley 56 rotates in the clockwise direction, and the rotation of the drive pulley 56 is transmitted to the driven pulley 55 through the belt 57. As a result, the driven pulley 55 and the first gear 51 that rotates therewith rotate in the clockwise direction, the second gear 52 that meshes with the first gear 51 rotates in the counterclockwise direction, and the third gear 53 that meshes with the second gear 52 rotates in the clockwise direction.

The feed roller 24 rotates clockwise together with the first gear 51 and shaft 24A. The pick-up roller 23 rotates clockwise together with the third gear 53 and shaft 23A.

As shown in FIG. 3, a guide gear 58 is rotatably provided on the shaft 52A of the second gear 52. The guide gear 58 is disposed outside the second gear 52 and rotates freely without receiving the rotational driving force of the second gear 52 and the shaft 52A.

As shown in Figures 3 and 4, a fourth gear 54 is fixed to the shaft 26A of each pressure roller 26. When the fourth gear 54 rotates, each pressure roller 26 and the shaft 26A rotate together.

A rack gear 59 is disposed near the fourth gear 54, and this rack gear 59 is fixed to the inside of the main body housing 21. When each L-shaped frame 29 rotates clockwise around the shaft 28, the guide gear 58 also rotates clockwise around the shaft 28, and the rack gear 59 curves along the maximum diameter movement trajectory described by the outer periphery of the guide gear 58. The guide gear 58 rotates clockwise around the shaft 28 until it reaches and meshes with the rack gear 59.

The drive unit 30 includes a coil spring 31 that urges each L-shaped frame 29 to rotate counterclockwise around the axis 28, and a solenoid 32 that rotates each L-shaped frame 29 clockwise around the axis 28.

When the coil spring 31 is in an extended state, both ends of the coil spring 31 are hooked onto the locking portion 61 of the main body housing 21 and the locking portion 62 of the arm portion 41 of the L-shaped frame 29. The coil spring 31 biases the arm portion 41 in a counterclockwise direction around the axis 28.

When the arm portion 41 rotates counterclockwise around the axis 28 due to the biasing force of the coil spring 31, each L-shaped frame 29 rotates counterclockwise around the axis 28, and the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 approaches and contacts the retard roller 25.

The plunger of the solenoid 32 is connected to the connecting portion 63 of the arm portion 41 of the L-shaped frame 29. When the solenoid 32 is energized, the solenoid 32 rotates the arm portion 41 clockwise around the axis 28 against the energizing force of the coil spring 31, causing each L-shaped frame 29 to rotate clockwise around the axis 28, and the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 moves away from the retard roller 25.

Next, the operating procedure of the paper feeder 20 will be explained with reference to Figures 5, 6, 7, etc.

Figures 5(A), (B), and (C) are a side view of the paper feeder 20 with each L-shaped frame 29 rotated counterclockwise and the pick-up roller 23 in contact with the feed roller 24, a side view of the gear unit 50 in the same state, and a plan view of the rollers 23-26 and the gear unit 50 in the same state. Figures 6(A), (B), and (C) are a side view of the paper feeder 20 with each L-shaped frame 29 rotated clockwise and the pick-up roller 23 in close proximity to the topmost sheet of recording paper on the paper feed tray 22, a side view of the gear unit 50 in the same state, and a plan view of the rollers 23-26 and the gear unit 50 in the same state. Furthermore, Figures 7(A), (B), and (C) are a side view of the paper feeder 20 with each L-shaped frame 29 rotated clockwise and the pick-up roller 23 in contact with the topmost sheet of recording paper on the paper feed tray 22, a side view of the gear unit 50 in the same state, and a plan view of the rollers 23-26 and the gear unit 50 in the same state.

Before the supply of recording paper P from the paper feed tray 22 begins, the solenoid 32 is de-energized as shown in Figures 5(A), (B), and (C), and the force of the coil spring 31 causes the arm portion 41 to rotate counterclockwise around the axis 28, causing each L-shaped frame 29 to rotate counterclockwise around the axis 28, and the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 comes into contact with the retard roller 25.

The drive pulley 56 is driven to rotate in a clockwise direction, and the rotation of the drive pulley 56 is transmitted to the driven pulley 55 via the belt 57, causing the driven pulley 55 and the first gear 51 to rotate in a clockwise direction, the second gear 52 meshing with the first gear 51 to rotate in a counterclockwise direction, and the third gear 53 meshing with the second gear 52 to rotate in a clockwise direction. The feed roller 24 rotates in a clockwise direction together with the first gear 51, and the pick-up roller 23 rotates in a clockwise direction together with the third gear 53.

As shown in Figures 6(A), (B), and (C), when the solenoid 32 is energized, the solenoid 32 rotates the arm portion 41 clockwise around the shaft 28 against the biasing force of the coil spring 31. Each L-shaped frame 29 rotates clockwise around the shaft 28, and as a result, the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 moves away from the retard roller 25, and the pickup roller 23 passes above each pressure roller 26.

The first gear 51, second gear 52, and third gear 53 also rotate clockwise around the axis 28 together with each L-shaped frame 29, and the third gear 53 passes above the fourth gear 54.

The guide gear 58, which is located on the outside of the shaft 52A of the second gear 52, begins to mesh with the rack gear 59.

As shown in Figures 7(A), (B), and (C), when each L-shaped frame 29 rotates clockwise around the axis 28, the arm portion 41 of each L-shaped frame 29 abuts against the stopper 65, each L-shaped frame 29 stops, and the pick-up roller 23 moves upstream of each pressure roller 26 in the direction in which the recording paper P is pulled out, and reaches a pull-out position (near the center of the topmost recording paper P on the paper feed tray 22) away from the leading edge of each recording paper P on the paper feed tray 22 and comes into contact with the topmost recording paper P.

The second gear 52 rotates counterclockwise and approaches and meshes with the fourth gear 54. At this time, the guide gear 58, which is supported rotatably around the shaft 52A of the second gear, continues to mesh with the rack gear 59, and the movement trajectories of the guide gear 58 and the second gear 52 are corrected by the rack gear 59, so that the second gear 52 reliably approaches and meshes with the fourth gear 54. In other words, the rack gear 59 guides the movement of the second gear 52 toward the upstream side and the downstream side. The rack gear 59 corresponds to the guide member in the claims. The second gear 52 corresponds to the rotation transmission member in the claims.

The pickup roller 23 rotates in a clockwise direction. The fourth gear 54 also rotates in a clockwise direction by meshing with the second gear 52, which rotates counterclockwise, causing each pressure roller 26 to also rotate in a clockwise direction.

The pickup roller 23 contacts the center of the topmost sheet of recording paper P on the paper feed tray 22. Each pressure roller 26 contacts the topmost sheet of recording paper P at a position close to the pickup roller 23. As the pickup roller 23 and each pressure roller 26 rotate in a clockwise direction, these rollers 23, 26 move the topmost sheet of recording paper P on the paper feed tray 22 toward the retard roller 25 (downstream in the direction in which the recording paper P is pulled out).

When the leading edge of the topmost recording paper P on the paper feed tray 22 reaches the position of the retard roller 25 (the conveying position of the recording paper P), the solenoid 32 is de-energized. When the solenoid 32 is de-energized, the L-shaped frames 29 rotate counterclockwise around the shaft 28 due to the biasing force of the coil spring 31, the pickup roller 23 moves away from the topmost recording paper P on the paper feed tray 22, and the second gear 52 moves away from the fourth gear 54, causing the fourth gear 54 and each pressure roller 26 to stop.

At this time, the pickup roller 23 moves away from the topmost recording paper P, and the pressure rollers 26 stop, so the movement of the topmost recording paper P stops. In addition, the stopped pressure rollers 26 come into contact with the topmost recording paper P to prevent the recording paper P from shifting out of position.

As shown in Figures 5(A), (B), and (C), each L-shaped frame 29 further rotates counterclockwise, and the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 is pressed against the leading edge of the topmost recording paper P, and the leading edge of the topmost recording paper P is sandwiched between the feed roller 24 and the retard roller 25. As the feed roller 24 rotates clockwise, it sends the topmost recording paper P to the transport roller 33, which then transports the recording paper P.

Then, the operational procedures shown in Figures 5, 6, and 7 are repeated, and each sheet of recording paper P on the paper feed tray 22 is pulled out and supplied one by one.

Figure 8 is a block diagram showing an example of a control system for the paper feeder 20. In Figure 8, a paper sensor 71 detects the leading edge of the recording paper P that has reached the position of the retard roller 25 (the transport position of the recording paper P). A control unit 72 determines the timing at which the leading edge of the recording paper P is detected by the paper sensor 71, and also controls the de-energization and energization of the solenoid 32.

Here, the control unit 72 de-energizes the solenoid 32 (stops the power supply) when the image forming device 10 is in a standby state. This causes each L-shaped frame 29 to rotate counterclockwise due to the biasing force of the coil spring 31, as shown in Figures 5(A), (B), and (C), and the feed roller 24 comes into contact with the retard roller 25.

When the image forming unit 12 of the image forming device 10 starts forming an image on the recording paper P, the control unit 72 determines the timing to start feeding the recording paper P and energizes the solenoid 32 (starts supplying power) at this timing. As a result, as shown in Figures 6 (A), (B), and (C), the solenoid 32 rotates each L-shaped frame 29 in a clockwise direction against the biasing force of the coil spring 31, the feed roller 24 moves away from the retard roller 25, and the pickup roller 23 passes above each pressure roller 26. Furthermore, as shown in Figures 7 (A), (B), and (C), the pickup roller 23 rotates in a clockwise direction and comes into contact with the center of the topmost recording paper P on the paper feed tray 22, and the second gear 52 meshes with the fourth gear 54, causing each pressure roller 26 to rotate in a clockwise direction, and the pickup roller 23 and each pressure roller 26 move the topmost recording paper P on the paper feed tray 22 toward the retard roller 25.

When the leading edge of the topmost recording paper P reaches the retard roller 25, the paper sensor 71 detects the leading edge of the recording paper P that has reached the retard roller 25. The control unit 72 de-energizes the solenoid 32 at the timing when the leading edge of the recording paper P is detected by the paper sensor 71. As shown in FIGS. 5(A), (B), and (C), each L-shaped frame 29 rotates counterclockwise, and the feed roller 24 rotates clockwise while being pressed against the leading edge of the topmost recording paper P, and the feed roller 24 sends the topmost recording paper P to the transport roller 33, which transports the recording paper P.

Similarly, when the image forming unit 12 starts forming an image on the recording paper P, the control unit 72 energizes the solenoid 32 at the timing when the recording paper P starts to be fed. As a result, as shown in Figures 6 (A), (B), (C) and Figures 7 (A), (B), (C), the pickup roller 23 comes into contact with the center of the topmost recording paper P on the paper feed tray 22, and the second gear 52 meshes with the fourth gear 54, causing each pressure roller 26 to rotate clockwise, and the pickup roller 23 and each pressure roller 26 move the topmost recording paper P on the paper feed tray 22 to the side of the retard roller 25. When the paper sensor 71 detects the leading edge of the recording paper P that has reached the retard roller 25, the control unit 72 deenergizes the solenoid 32. As a result, the feed roller 24 is pressed against the leading edge of the topmost recording paper P as shown in Figures 5 (A), (B), and (C), and sends the recording paper P to the transport roller 33.

In this way, in the first embodiment, the pickup roller 23 and the feed roller 24 are rotated clockwise around the axis 28 of each L-shaped frame 29, and the pickup roller 23 is brought into contact with the vicinity of the center of the topmost recording paper P on the paper feed tray 22, and the topmost recording paper P is pulled out by the pickup roller 23 and each pressure roller 26. Therefore, even if the position of each recording paper P on the paper feed tray 22 is shifted, the topmost recording paper P can be reliably pulled out.

In addition, while the pickup roller 23 and the feed roller 24 are rotating counterclockwise around the axis 28 of each L-shaped frame 29 and the feed roller 24 is returning to the position of the retard roller 25, each pressure roller 26 is stopped and each pressure roller 26 presses down the topmost recording paper P, so that the position of the topmost recording paper P can be maintained.

Furthermore, with the feed roller 24 separated from the retard roller 25, the leading edge of the topmost recording paper P is moved to the retard roller 25 by the pickup roller 23 and each pressure roller 26, and then the feed roller 24 is pressed against the leading edge of the topmost recording paper P, and the topmost recording paper P is fed out by the feed roller 24, so that the topmost recording paper P can be fed out reliably.
Second Embodiment
9A, 9B, and 9C are side views showing a paper feeder according to a second embodiment of the present invention, and show the operation procedure of the paper feeder. Also, Fig. 10 is a plan view showing the inside of the paper feeder according to the second embodiment. In Fig. 9 and Fig. 10, parts that perform the same functions as those in Fig. 1 are given the same reference numerals.

In the paper feeder 20A of the second embodiment, the first gear 51 to the fourth gear 54 of the gear unit 50 in the first embodiment are omitted, and an intermediate roller 67 is provided. The intermediate roller 67 is fixed to the shaft 52A supported by the support portion 42 of each L-shaped frame 29, and rotates freely together with the shaft 52A. The intermediate roller 67 is also disposed between the pick-up roller 23 and the feed roller 24, and contacts both of these rollers 23 and 24. Furthermore, the width of the intermediate roller 67 is set to be equal to the length from one outer end to the other outer end of each pressure roller 26, and contacts each pressure roller 26 when each L-shaped frame 29 is rotated clockwise as shown in FIG. 9(C).

Before the supply of recording paper P from the paper feed tray 22 begins, the solenoid 32 is de-energized as shown in FIG. 9(A), and the L-shaped frames 29 rotate counterclockwise around the axis 28 due to the biasing force of the coil spring 31, and the feed roller 24 comes into contact with the retard roller 25.

The drive pulley 56 is driven to rotate in the clockwise direction, and the rotation of the drive pulley 56 is transmitted to the driven pulley 55 via the belt 57, causing the driven pulley 55 to rotate in the clockwise direction. The feed roller 24 rotates in the clockwise direction together with the driven pulley 55. In addition, the intermediate roller 67 is in contact with the feed roller 24 rotating in the clockwise direction, and therefore is driven to rotate in the counterclockwise direction. Furthermore, the pick-up roller 23 is in contact with the intermediate roller 67 rotating in the counterclockwise direction, and therefore is driven to rotate in the clockwise direction. Therefore, the feed roller 24 and the pick-up roller 23 rotate in the clockwise direction.

As shown in FIG. 9(B), when the solenoid 32 is energized, the solenoid 32 rotates each L-shaped frame 29 clockwise around the axis 28 against the energizing force of the coil spring 31, the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 moves away from the retard roller 25, and the pickup roller 23 passes above each pressure roller 26. Also, the guide gear 58 begins to mesh with the rack gear 59.

As shown in FIG. 9(C), each L-shaped frame 29 rotates further in the clockwise direction, and the pick-up roller 23 moves upstream of each pressure roller 26 in the direction in which the recording paper P is pulled out, and the pickup roller 23 reaches a pull-out position (near the center of each recording paper P on the paper feed tray 22) away from the leading edge of each recording paper P on the paper feed tray 22 and comes into contact with the topmost recording paper P.

The intermediate roller 67 rotates counterclockwise while contacting each pressure roller 26, and each pressure roller 26 rotates clockwise, similar to the feed roller 24 and the pickup roller 23. The intermediate roller 67 functions as a rotation transmission member in the claims.

At this time, the guide gear 58 continues to mesh with the rack gear 59, and the rack gear 59 corrects the movement trajectory of the intermediate roller 67.

The pickup roller 23 contacts the center of the topmost sheet of recording paper P on the paper feed tray 22. Each pressure roller 26 contacts the topmost sheet of recording paper P at a position close to the pickup roller 23. The pickup roller 23 and each pressure roller 26 rotate clockwise to move the topmost sheet of recording paper P on the paper feed tray 22 toward the retard roller 25 (downstream in the direction in which the recording paper P is pulled out).

When the leading edge of the topmost recording paper P on the paper feed tray 22 reaches the position of the retard roller 25 (the transport position of the recording paper P), the solenoid 32 is de-energized. Due to the biasing force of the coil spring 31, each L-shaped frame 29 rotates counterclockwise around the axis 28, the pickup roller 23 moves away from the topmost recording paper P on the paper feed tray 22, and the intermediate roller 67 moves away from each pressure roller 26, causing each pressure roller 26 to stop.

At this time, the pickup roller 23 moves away from the topmost recording paper P, and the pressure rollers 26 stop, so the movement of the topmost recording paper P stops. In addition, the stopped pressure rollers 26 come into contact with the topmost recording paper P to prevent the recording paper P from shifting out of position.

As shown in FIG. 9(A), each L-shaped frame 29 further rotates counterclockwise, and the feed roller 24 supported by the support portion 42 of each L-shaped frame 29 is pressed against the retard roller 25 via the leading edge of the topmost recording paper P. As the feed roller 24 rotates clockwise, it sends the topmost recording paper P to the transport roller 33, which then transports the recording paper P.

Then, the operational procedures shown in Figures 9(A), (B), and (C) are repeated in the same manner, and each sheet of recording paper P on the paper feed tray 22 is pulled out and fed one by one.

In this way, in the second embodiment, as in the first embodiment, the pickup roller 23 is in contact with the center of the topmost recording paper P on the paper feed tray 22, and the pickup roller 23 and each pressure roller 26 pull out the topmost recording paper P. Therefore, even if the position of each recording paper P on the paper feed tray 22 is shifted, the topmost recording paper P can be reliably pulled out.

In addition, when the feed roller 24 is returned to the position of the retard roller 25, the topmost recording paper P is pressed down by each of the stopped pressure rollers 26, so the position of the topmost recording paper P can be maintained.

Furthermore, with the feed roller 24 separated from the retard roller 25, the leading edge of the topmost recording paper P is moved to the retard roller 25, and then the feed roller 24 is pressed against the leading edge of the topmost recording paper P, and the topmost recording paper P is fed out by the feed roller 24, so that the topmost recording paper P can be fed out reliably.

In addition, since the rotational driving force is transmitted from the feed roller 24 to the pickup roller 23 via the intermediate roller 67, and also from the feed roller 24 to each pressure roller 26 via the intermediate roller 67, the first gear 51 to the fourth gear 54 in the gear unit 50 can be omitted.

Note that the configuration and processing of the above embodiment described using Figures 1 to 10 is merely one embodiment of the present invention, and is not intended to limit the present invention to such configuration and processing.

REFERENCE SIGNS LIST 10 Image forming apparatus 11 Image reading section 12 Image forming section 20 Paper feeder 21 Main body housing 22 Paper feed tray 23 Pick-up roller 24 Feed roller 25 Retard roller 26 Presser roller 27 Lifting device 29 L-shaped frame 30 Driving section 50 Gear unit 52 Second gear 59 Rack gear

Claims (5)

a paper tray on which a plurality of papers are stacked;
a pick-up roller for picking up each of the sheets of paper from the paper tray one by one;
a feed roller that conveys the paper sheet picked up by the pickup roller;
a support portion that supports the pickup roller and supports the feed roller downstream of the pickup roller in a paper pull-out direction;
an arm supported at one end so as to be rotatable around an axis provided below the paper tray toward the upstream and downstream sides in the paper pull-out direction, and supporting the support portion at the other end remote from the axis;
a drive unit that rotates the arm about the axis toward the upstream side in the pull-out direction to move the pickup roller supported by the support unit to a pull-out position separated from the leading edge of each of the sheets of paper on the paper tray toward the upstream side in the pull-out direction, and then rotates the arm about the axis toward the downstream side in the pull-out direction to move the feed roller supported by the support unit to a transport position downstream of the pull-out position in the pull-out direction,
When the pickup roller is moved to the pull-out position, the pickup roller comes into contact with the topmost sheet of the sheets on the paper tray and pulls out the topmost sheet of the sheets;
When the feed roller is moved to the transport position, the feed roller comes into contact with the topmost sheet of paper pulled out by the pickup roller and transports the topmost sheet of paper. a pressure roller that contacts the topmost sheet of each of the sheets;
2. The paper feeding device according to claim 1, further comprising: a rotation transmission member that is supported by the support portion, moves together with the pickup roller, and when the pickup roller is moved to the pull-out position, rotates the pressure roller in conjunction with the pickup roller, causing the pressure roller to pull out the topmost sheet of paper. The paper feeder according to claim 2, further comprising a guide member that is provided along a movement path of the rotation transmission member accompanying the rotation of the arm toward the upstream side in the pull-out direction and that guides the movement of the rotation transmission member toward the upstream side and the downstream side. The paper feeder according to any one of claims 1 to 3, wherein the drive unit has a stopper that limits the rotation of the arm upstream in the pull-out direction and the movement of the pickup roller to the pull-out position. A paper feeder according to any one of claims 1 to 4,
an image forming unit that forms an image on the recording paper fed from the paper feeder.