Patent Application
20240383707
This application claims priority to Japanese Patent Application No. 2023-081112 filed on May 16, 2023, the entire contents of which are incorporated by reference herein.
The present disclosure relates to a paper transport apparatus for transporting paper and an image forming apparatus including the same. In particular, the present disclosure relates to technology for switching a paper transport direction.
In an image forming apparatus, recording paper (an example of paper) is transported to an image forming device through a first transport path and the recording paper is ejected into a paper ejection tray through an ejection roller after an image of a manuscript is formed on a front side of the recording paper by the image forming device. Moreover, when an image of the manuscript is formed on a back side of the recording paper, the recording paper is transported to the ejection roller, switchback transport in which the ejection roller is temporarily stopped and reversely rotated is performed, the recording paper is transported in a direction opposite to a previous transport direction, the recording paper returns to the first transport path through a second transport path, the front and back sides of the recording paper are reversed, an image of the manuscript is formed on the back side of the recording paper by the image forming device, and the recording paper is ejected into the paper ejection tray through the ejection roller.
Moreover, there is a paper transport apparatus that transports recording paper from a carrying-in transport path to a reverse transport path, switches a paper transport direction to a reverse direction on the reverse transport path, and transports the recording paper from the reverse transport path to a paper ejection transport path. In order to switch the recording paper transport direction, a first branch pawl and a second branch pawl for switching the paper transport direction to a branch of the carrying-in transport path, the reverse transport path, and the paper ejection transport path are provided and a roller for transporting the paper to the reverse transport path in the reverse direction is provided.
As an aspect of the present disclosure, technology obtained by further improving the above-described technology is proposed.
According to an aspect of the present disclosure, a paper transport apparatus includes a first transport path, a roller, a second transport path, a switching guide, a first link member, a paper detection member, a second link member, a driven rotation member, a sensor, a drive device, and a controller. The first transport path is configured to guide paper. The roller transports the paper guided through the first transport path. The second transport path is configured to guide the paper transported in a direction opposite to a transport direction on the first transport path according to reverse rotation of the roller. The switching guide is rotationally supported according to a first shaft parallel to the roller and rotated back and forth around the first shaft to switch a transport direction of the paper by moving to either a first transport position for guiding the paper guided through the first transport path to the roller or a second transport position for guiding the paper transported in the opposite direction according to the reverse rotation of the roller to the second transport path. The first link member is rotatably supported by the first shaft, protrudes in a direction perpendicular to the first shaft, and rotates back and forth integrally with the switching guide around the first shaft. The paper detection member is rotatably supported by a second shaft parallel to the first shaft, protrudes toward the first transport path, rotates around the second shaft, and retreats from the first transport path when the paper detection member comes into contact with the paper transported through the first transport path. The second link member is rotatably supported by the second shaft and rotates integrally with the paper detection member around the second shaft when the paper detection member retreats from the first transport path. The driven rotation member is rotatably supported by a third shaft parallel to the first shaft, pressed and rotated by the first link member when the switching guide is switched to the second transport position and the first link member rotates, and pressed and rotated by the second link member when the paper detection member retreats from the first transport path and the second link member rotates. The sensor detects a standby position of the driven rotation member when the driven rotation member is not pressed by either the first link member or the second link member. The drive device rotates the switching guide back and forth around the first shaft and switches the switching guide to either the first transport position or the second transport position. The controller determines that the paper is being transported through the first transport path when the paper detection member retreats in contact with the paper transported through the first transport path in a state in which the switching guide is switched to the first transport position by controlling the drive device, the second link member rotates, the driven rotation member is pressed and rotated by the second link member, and the standby position of the driven rotation member is not detected by the sensor and determines that the switching guide has been switched from the first transport position to the second transport position when the first link member rotates with the switching guide after the switching guide is switched to the second transport position by controlling the drive device, the driven rotation member is pressed and rotated by the first link member, and the standby position of the driven rotation member is not detected by the sensor.
According to an aspect of the present disclosure, an image forming apparatus includes the paper transport apparatus according to the above-described aspect of the present disclosure and an image forming device configured to form an image on the paper transported by the paper transport apparatus.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Hereinafter, a rotational direction or left, right, up, and down directions may be shown, but these are the directions of the examples in each drawing unless otherwise stated.
The image reading device 11 includes an image sensor (a CCD sensor or a contact image sensor) that optically reads an image of a manuscript and an output of the image sensor is converted into image data.
The image forming device 12 prints an image indicated in the above-described image data on recording paper 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 any one of the image forming units 3M, 3C, 3Y, and 3Bk, a surface of a photoreceptor drum 4 is uniformly charged, the surface of the photoreceptor drum 4 is exposed, an electrostatic latent image is formed on the surface of the photoreceptor drum 4, the electrostatic latent image on the surface of the photoreceptor drum 4 is developed into a toner image, and the toner image on the surface of the photoreceptor drum 4 is transferred to an intermediate transfer belt 5. Thereby, a colored toner image is formed on the intermediate transfer belt 5. This colored toner image is secondarily transferred to recording paper P transported from a paper feed device 14 through the first transport path 8 in a nip region N between the intermediate transfer belt 5 and a secondary transfer roller 6.
Subsequently, the recording paper P is heated and pressurized by a fixing device 15 to fix the toner image on the recording paper P through thermocompression bonding, and the recording paper P is ejected into a paper ejection tray 17 through an ejection roller 16.
Moreover, when the image of the manuscript is recorded on the back side of the recording paper P, switchback transport in which the recording paper P is transported to the ejection roller 16 in front of the paper ejection tray 17, the ejection roller 16 is temporarily stopped and then reversely rotated, and the recording paper P is transported in the reverse direction is performed, the position of the switching guide 18 provided at a branch position of the first transport path 8 and the second transport path 9 is switched, the recording paper P is guided from the ejection roller 16 to a second transport path 9, the recording paper P returns to the first transport path 8 through the second transport path 9, the front and back sides of the recording paper P are reversed, the image forming device 12 forms the image of the manuscript on the back side of the recording paper P, and the recording paper P is ejected into the paper ejection tray 17 through the ejection roller 16.
When the above-described switchback transport is performed, after the rear end of the recording paper passes through the switching guide 18 during the transportation of the recording paper by the ejection roller 16, the ejection roller 16 is temporarily stopped when the ejection roller 16 is nipping the recording paper. The switching guide 18 is switched from the first transport position HS1 to the second transport position HS2 and the ejection roller 16 is reversely rotated. The recording paper is transported by the ejection roller 16 in a direction opposite to the previous transport direction and is guided to the second transport path 9 by the switching guide 18 at a branch position of the first transport path 8 and the second transport path 9. Also, the recording paper returns to the first transport path 8 through the second transport path 9, and the front and back sides of the recording paper are reversed.
As shown in
The driven rotation member 26 is rotatably supported by a shaft 23 (a third shaft in the claims) parallel to the shaft 21. The driven rotation member 26 includes a bearing device 26A rotatably supported by the shaft 23, a contact arm 26B and a swing arm 26C connected and fixed to the bearing device 26A, and a detected piece 26D bent inward and protruding at a lower end of the swing arm 26C. The contact arm 26B and the swing arm 26C have a bent shape at a position of the bearing device 26A.
The sensor 27 is an optical sensor in which a light emitting element 27A and a light receiving element 27B are arranged facing each other in the up/down direction and the detected piece 26D at the lower end of the swing arm 26C that penetrates between the light emitting element 27A and the light receiving element 27B is detected.
The shaft 21 for supporting the switching guide 18 is rotatably supported by a frame 31 inside the paper transport apparatus 20. Likewise, the shaft 22 for supporting the paper detection member 25 is rotatably supported by the frame 31 inside the paper transport apparatus 20. Moreover, the shaft 23 for supporting the driven rotation member 26 protrudes inward from an inner wall (not shown) of a housing of the paper transport apparatus 20 and is inserted into the bearing device 26A of the driven rotation member 26. The shaft 23 rotatably supports the driven rotation member 26 around the shaft 23.
Moreover, when the solenoid 34 is activated and driven, the solenoid 34 pulls the plunger 35 against a biasing force of the spring, and the guide member 33 follows the plunger 35 and rotates in a counterclockwise direction. Simultaneously, each switching guide 18 and the first link member 24 rotate in the counterclockwise direction and each switching guide 18 is positioned at the second transport position HS2.
As shown in
When the solenoid 34 is deactivated as shown in
The paper detection member 25 is biased and rotated in the counterclockwise direction around the shaft 22 due to its weight and the tip of the paper detection member 25 enters the recess formed in the wall of the first transport path 8. At this time, the stopper 29 rotates in the counterclockwise direction around the shaft 22 and stops in contact with a part 31A of the frame 31 inside the paper transport apparatus 20, the paper detection member 25 stops in a substantially horizontal direction, and the second link member 28 stops facing upward.
The driven rotation member 26 is biased and rotated in the counterclockwise direction around the shaft 23 due to its weight and the bent inclined surface 26F of the contact arm 26B of the driven rotation member 26 is in contact with the sliding contact surface 28A of the second link member 28 and the driven rotation member 26 stops. At this time, the swing arm 26C of the driven rotation member 26 stops facing downward and the sensor 27 detects the detected piece 26D of the swing arm 26C.
Therefore, when the swing arm 26C of the driven rotation member 26 is facing downward and the driven rotation member 26 is at a preset standby position, the sensor 27 detects the detected piece 26D at the lower end of the swing arm 26C.
A state in which the solenoid 34 is deactivated is maintained as shown in
When the recording paper P is transported through the first transport path 8, the tip of the paper detection member 25 is pushed up in contact with the recording paper P, the paper detection member 25 rotates in the clockwise direction around the shaft 22, and the second link member 28 also rotates in the clockwise direction. At this time, the sliding contact surface 28A of the second link member 28 pushes away the bent inclined surface 26F of the contact arm 26B of the driven rotation member 26 in a right direction, the driven rotation member 26 rotates in the clockwise direction around the shaft 23, and the detected piece 26D of the swing arm 26C of the driven rotation member 26 is removed from a detection position of the sensor 27.
Therefore, in the state in which the recording paper P is transported through the first transport path 8, the driven rotation member 26 is at a position outside the standby position and the sensor 27 does not detect the detected piece 26D at the lower end of the swing arm 26C.
When the solenoid 34 is activated as shown in
When the first link member 24 rotates in the counterclockwise direction, the sliding contact surface 24A of the first link member 24 pushes away the smooth surface 26E of the contact arm 26B of the driven rotation member 26 in the right direction, the driven rotation member 26 rotates in the clockwise direction around the shaft 23, and the detected piece 26D of the swing arm 26C of the driven rotation member 26 is removed from a detection position of the sensor 27.
Therefore, in a state in which each switching guide 18 is moved from the first transport position HS1 to the second transport position HS2, the driven rotation member 26 is at a position outside the standby position and the sensor 27 does not detect the detected piece 26D at the lower end of the swing arm 26C.
That is, as shown in
The transport device 41 includes a motor, a clutch, and the like for rotating each transport roller in the first transport path 8, each transport roller in the second transport path 9, the ejection roller 16, and the like and transports the recording paper P through the first transport path 8 or the second transport path 9. As shown in
The controller 44 controls the transport device 41 so that the recording paper P is transported through the first transport path 8 or the second transport path 9, activates or deactivates the solenoid 34 to switch each switching guide 18 to the first transport position HS1 or the second transport position HS2, and further determines that the driven rotation member 26 is at a standby position or a position outside the standby position on the basis of the detection output of the sensor 27.
Here, in order to appropriately control the recording paper transport operation of the paper transport apparatus 20, it is necessary to detect the presence or absence of recording paper being transported through the first transport path 8 and to detect that each switching guide 18 has been moved from the first transport position HS1 to the second transport position HS2 according to the activation of the solenoid 34. However, if a sensor for detecting the presence or absence of the recording paper and a sensor for detecting the second transport position HS2 of each switching guide 18 are provided separately, the cost increases.
Therefore, in the paper transport apparatus 20 of the present embodiment, while only the sensor 27 is provided, it is possible to determine both the presence or absence of recording paper and the second transport position HS2 of each switching guide 18.
Next, a control procedure for determining the presence or absence of recording paper P being transported through the first transport path 8 and the second transport position HS2 of each switching guide 18 will be described with reference to the flowchart shown in
The controller 44 deactivates the solenoid 34 as shown in
As shown in
The controller 44 determines that the driven rotation member 26 is not outside of the standby position on the basis of the detection output of the sensor 27 before the recording paper P reaches the tip of the paper detection member 25 (“No” in S104), determines that the recording paper P is being transported through the first transport path 8 (S105) if the recording paper P reaches the tip of the paper detection member 25 and the driven rotation member 26 moves to a position outside the standby position (“Yes” in S104), starts the measurement of the elapsed time T (S106), determines whether or not the elapsed time T is greater than or equal to a prescribed time t (S107), and determines whether or not the driven rotation member 26 has returned to the standby position on the basis of the detection output of the sensor 27 (S108).
The prescribed time t is a period from the time when the tip of the paper detection member 25 is pushed up in contact with the recording paper P to the time when it returns to an original position (the time when the recording paper P passes through the position of the tip of the paper detection member 25) and is obtained in advance on the basis of the length of the recording paper P and the transport speed of the recording paper P.
For example, when the controller 44 determines that the driven rotation member 26 has returned to the standby position on the basis of the detection output of the sensor 27 (“Yes” in S108) before the elapsed time T is greater than or equal to the prescribed time t (“No” in S107), the recording paper P is normally transported, the rear end of the recording paper P passes through the position of the tip of the paper detection member 25, and the tip of the paper detection member 25 returns to its original position as shown in
Moreover, when the controller 44 determines that the driven rotation member 26 has not returned to the standby position (“No” in S108) and the elapsed time T is greater than or equal to the prescribed time t (“Yes” in S107), because the recording paper P is not transported normally, the rear end of the recording paper P does not pass through the position of the tip of the paper detection member 25, and there is a possibility that a jam will occur, the paper transport apparatus 20 is stopped and a message indicating the occurrence of the jam is displayed on the display device 43 (S110) and the control procedure shown in
Moreover, when it is determined that there is printing on the back side of the recording paper P (“Yes” in S109), the controller 44 controls the transport device 41 and stops the ejection roller 16 after a preset first time from a point in time when the driven rotation member 26 returns to the standby position on the basis of the detection output of the sensor 27, i.e., a point in time when the rear end of the recording paper P passes through the position of the tip of the paper detection member 25 (S111). Also, as shown in
At this time, the first link member 24 rotates in the counterclockwise direction with each switching guide 18, the sliding contact surface 24A of the first link member 24 pushes away the smooth surface 26E of the contact arm 26B of the driven rotation member 26 in the right direction, the driven rotation member 26 rotates in the clockwise direction, and the detected piece 26D of the swing arm 26C of the driven rotation member 26 is removed from the detection position of the sensor 27.
If the controller 44 waits for the driven rotation member 26 to move to a position outside the standby position on the basis of the detection output of the sensor 27 (“No” in S113) simultaneously with the time when the solenoid 34 is activated and the driven rotation member 26 moves to a position outside the standby position (“Yes” in S113), each switching guide 18 is moved from the first transport position HS1 to the second transport position HS2, such that it is determined that each switching guide 18 has been moved from the first transport position HS1 to the second transport position HS2, the transport device 41 is controlled to reversely rotate the ejection roller 16 (S114), and the recording paper P is guided from the ejection roller 16 to the second transport path 9. Thereby, the recording paper P is transported in the switchback transport.
When a predetermined second time has elapsed after the reverse rotation of the ejection roller 16, the controller 44 stops the ejection roller 16, deactivates the solenoid 34 again, and moves each switching guide 18 from the second transport position HS2 to the first transport position HS1 as shown in
As described above, in the present embodiment, the first link member 24, the paper detection member 25, the driven rotation member 26, the sensor 27, the second link member 28, and the like are used to determine the presence or absence of recording paper being transported through the first transport path 8 and the second transport position HS2 of each switching guide 18, it is possible to implement cost reduction without increasing the number of sensors.
On the other hand, in the case of a general paper transport apparatus other than the present embodiment, in a configuration in which a plurality of transport paths are provided and the transport path along which the paper is transported is switched by the branch pawl, it is necessary to detect the recording paper being transported through the transport path, the position the branch pawl, and the like and a configuration necessary for this detection is complex. For example, the number of motors, the number of solenoids, and the number of sensors increase and hence the cost also increases.
According to the present embodiment, in a mechanism for switching the paper transport direction, a constituent element for detecting the recording paper being transported through the transport path, the position of the branch pawl, and the like can be implemented with a simpler configuration.
Furthermore, the configuration and process of the above-described embodiment described with reference to
While the present disclosure has been described in detail with reference to the embodiments thereof, it would be apparent to those skilled in the art that the various changes and modifications may be made therein within the scope defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-081112 | May 2023 | JP | national |
