Image forming apparatus

Abstract

To provide an image forming apparatus that enables stable correction of sheet skew. [Solution] An image forming apparatus according to one embodiment of this technology comprises a shutter member and a control member. The shutter member is provided along a sheet transport path and has an open state in which the sheet can pass through, or a closed state in which the sheet cannot pass through, and the shutter member becomes open when it receives a force of a predetermined magnitude from the sheet by the leading edge of the sheet coming into contact with it. The control member is capable of controlling the change of the predetermined magnitude.

Description

Technical Field

[0001] The present technology relates to an image forming apparatus applicable to a printer or the like.

Background Art

[0002] Patent Document 1 discloses a sheet conveyance apparatus capable of correcting skew of a sheet. This sheet conveyance apparatus has a locking member with which the sheet abuts, and the locking member waits at a retracted position when the sheet passes therethrough. Thereby, it becomes possible to improve throughput.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such an image forming apparatus, a technique that enables stable correction of skew of a sheet is required.

[0005] In view of the above circumstances, an object of the present technology is to provide an image forming apparatus capable of stably correcting skew of a sheet.

Means for Solving the Problems

[0006] To achieve the above object, an image forming apparatus according to an aspect of the present technology includes a shutter member and a control member. The shutter member is provided along a conveyance path of a sheet, and has an open state in which the sheet can pass therethrough or a closed state in which the sheet cannot pass therethrough, and becomes the open state when receiving a force of a predetermined magnitude from the sheet by contact of a leading end of the sheet. The control member is capable of controlling to change the predetermined magnitude.

[0007] In this image forming apparatus, a shutter member is provided that opens to allow the sheet to pass through when the leading edge of the sheet makes contact and receives a predetermined force from the sheet. Control is also performed to change this predetermined force. This makes it possible to stably correct the skew of the sheet.

[0008] The control member may include a spring that elastically biases the shutter member so that the shutter member is in the closed state.

[0009] The control member may have an expansion / contraction mechanism that changes the elastic force by expanding or contracting the spring.

[0010] The telescopic mechanism may include a drive source for extending and contracting the spring.

[0011] The telescopic mechanism may include at least one of a rack or pinion that transmits the force of the drive source to the spring.

[0012] The image forming apparatus may further include a pair of rollers positioned on the transport path that feed out the sheet by gripping it. In this case, the shutter member may be connected to the pair of rollers, and the open state may be a state in which the sheet can pass through the pair of rollers, while the closed state may be a state in which the sheet cannot pass through the pair of rollers.

[0013] The image forming apparatus may further include an image forming unit positioned downstream of the shutter member in the transport path, which forms an image on the sheet. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing an example of the configuration of an image forming apparatus according to one embodiment of this technology. [Figure 2] This is a schematic diagram showing an example of the configuration of a shutter component. [Figure 3] It is a schematic diagram showing a configuration example of a control member. [Figure 4] It is a perspective view showing a detailed configuration example of a control member. [Figure 5] It is a side view showing a detailed configuration example of a control member.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments according to the present technology will be described while referring to the drawings.

[0016] [Image Forming Apparatus] FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus 1 according to an embodiment of the present technology. In FIG. 1, the inside of the image forming apparatus 1 is shown. The image forming apparatus 1 is a printer that forms a color image on a sheet 2 by an inkjet method. The image forming apparatus 1 may be other types of printers, fax machines, copiers, multifunction devices, etc.

[0017] Here, for convenience, an XYZ coordinate system is defined with respect to the drawings. When viewed from the direction in which the positive side of the Z axis is the upper side and the positive side of the X axis is the right side, the positive side of the Y axis is the back side (that is, a right-handed coordinate system). In the present embodiment, with the Z direction as the vertical direction (gravity direction) and the X and Y directions as the horizontal directions, the image forming apparatus 1 is arranged as shown in FIG. 1. Note that the orientation in which the image forming apparatus 1 is used is not limited with respect to the application of the present technology.

[0018] The image forming apparatus 1 includes a paper feed cassette 3 (3a, 3b), pick rollers 4 (4a, 4b), roller pairs 5 (5a to 5n), a conveyance guide 6, a sensor 7, pulleys 8 (8a, 8b), a conveyance belt 9, a line head 10, an ink storage unit 11, flaps 12 (12a, 12b), and a discharge tray 13 (13a, 13b).

[0019] The paper feed cassette 3 is a cassette for accommodating the paper 2. The paper 2 is a single-sheet paper that has been pre-cut into a rectangular shape. In the present embodiment, a plurality of papers 2 are placed horizontally and parallel inside the paper feed cassette 3.

[0020] The specific shape of the paper 2 is not limited, and the shape may be changed as appropriate within the range where the present technology can be realized. In the present embodiment, two paper feed cassettes 3a and 3b are provided, and different types of papers 2 are accommodated therein. For example, plain paper and thin paper are accommodated in the paper feed cassette 3a, and thick paper is accommodated in the paper feed cassette 3b. In addition, any type of sheet may be accommodated in the paper feed cassette 3. Also, only one or three or more paper feed cassettes 3 may be used. The paper 2 corresponds to one embodiment of the sheet according to the present technology.

[0021] The pick roller 4a is rotated by a drive source such as a motor, and thereby feeds out the uppermost paper 2 in the paper feed cassette 3a to the conveyance path 14. In FIG. 1, the conveyance path 14 is shown by a broken line. Note that the conveyance path 14 in FIG. 1 is merely an example, and its specific path is not limited.

[0022] The roller pair 5 consists of two rollers. For example, when one of them is rotated by a drive source, the paper 2 is fed out by being sandwiched. Since the conveyance path 14 through which the paper 2 passes is formed between the roller pair 5, it can be said that the roller pair 5 is arranged along the conveyance path 14. The specific number and position of the roller pair 5 are not limited.

[0023] Hereinafter, the side of the conveyance path 14 through which the paper 2 passes first is referred to as the upstream side, and the side through which it passes later is referred to as the downstream side. As shown in FIG. 1, the paper 2 fed out by the pick roller 4a first passes through the roller pair 5a and then passes through the downstream roller pair 5f while being conveyed along the conveyance path 14. Although not shown in the figure, conveyance guides for guiding the paper 2 along the conveyance path 14 are appropriately provided between the roller pairs 5a and 5f. The same applies to between the other roller pairs 5.

[0024] The pick roller 4b is rotated by the drive source, which feeds the top sheet of paper 2 in the paper cassette 3b to the transport path 14. The paper 2 passes through roller pairs 5b, 5c, 5e, and 5f in that order.

[0025] In this embodiment, paper 2 fed from an expansion unit (not shown) is transported along transport path 14a and merges into transport path 14 between roller pairs 5c and 5e. Paper 2 fed from a manual feed tray is transported along transport path 14b, passes through roller pair 5d, and reaches roller pair 5e. The expansion unit, manual feed tray, transport paths 14a and 14b, and roller pair 5d are not required to be configured.

[0026] The transport path 14c between roller pairs 5f and 5g is curved. The transport guide 6 has a curved shape similar to that of the transport path 14c and is provided along the transport path 14c. In this embodiment, the transport guide 6 is provided on the left side (negative side in the X direction) of the transport path 14c.

[0027] A sensor 7 is located further to the left of the transport guide 6. That is, the sensor 7 is located on the opposite side of the transport path 14c from the transport guide 6. When the paper 2 passes through the transport path 14c, the position of the edge of the paper 2 is detected by the sensor 7.

[0028] A shutter member 15 is connected to the roller pair 5g. The detailed configuration of the shutter member 15 will be described later.

[0029] The pulley 8, conveyor belt 9, and line head 10 are positioned between roller pairs 5g and 5h. The conveyor belt 9 is an endless belt, wrapped around and held by pulleys 8a and 8b. When one or both of the pulleys 8a and 8b are rotated by a drive source, the conveyor belt 9 also rotates. The surface of the conveyor belt 9 (the upper left side) is part of the conveyor path 14, and as the conveyor belt 9 rotates, the paper 2 also moves from the upstream side to the downstream side. In order to fix the paper 2 to the surface of the conveyor belt 9, holes are provided in the surface of the conveyor belt 9, and the paper 2 is attracted by negative pressure through these holes.

[0030] The line head 10 is positioned opposite the surface of the conveyor belt 9 and ejects black, cyan, magenta, and yellow ink onto the paper 2 at predetermined timings. This forms a color image on the paper 2. The ink ejected from the line head 10 is supplied from the ink storage unit 11 via tubes or the like (not shown). The line head 10 corresponds to one embodiment of the image forming unit, which is positioned downstream of the shutter member 15 in the transport path 14.

[0031] If double-sided printing is not performed after paper 2 has passed roller pair 5h, flap 12a transports paper 2 to the left side of the branch path. Next, flap 12b transports paper 2 in either the direction of roller pair 5i or 5j. Paper 2 transported to roller pair 5i is discharged to output tray 13a. Paper 2 transported to roller pair 5j passes through roller pair 5k and is then discharged to output tray 13b. In this example, two output trays 13 are provided, making it possible to separate the output destination of printed materials for each person who performed the printing. Alternatively, only one output tray 13 may be provided.

[0032] After paper 2 passes roller pair 5h, if double-sided printing is to be performed, the flap 12a transports paper 2 to the right side of the branch path. After passing roller pair 5l, paper 2 switches back and passes roller pairs 5m and 5n to reach roller pair 5e. Thereafter, the line head 10 similarly forms an image on the unprinted surface of paper 2, and it is discharged into the output tray 13a or 13b.

[0033] Furthermore, the specific configuration of the image forming apparatus 1 is not limited. For example, it may include a drying mechanism for drying the ink adhering to the paper 2, or an inspection device for inspecting the formed image.

[0034] [Shutter components] Figure 2 is a schematic diagram showing an example of the configuration of the shutter member 15. Figure 2 shows the roller pair 5f, 5g, and shutter member 15 from Figure 1. The transport path 14c between roller pair 5f and 5g is shown as a dashed line, and the paper 2 being transported along the transport path 14c is also shown. Note that the transport guide 6 and sensor 7 are not shown. For convenience, the roller on the right side of roller pair 5g will be referred to as roller 16a, and the roller on the left side as roller 16b.

[0035] The detailed configuration of the shutter member 15 will be described later, but as shown in Figure 2, the shutter member 15 is connected to the roller 16a on the right side. Since the roller 16a is provided along the transport path 14c, it can be said that the shutter member 15 is also provided along the transport path 14c.

[0036] The shutter member 15 is configured to rotate around the same axis of rotation as the roller 16a. By rotating, the shutter member 15 can be in an open state and a closed state. The open state is shown in Figure 2B, in which the shutter member 15 rotates clockwise and does not block the part that becomes the transport path 14 for the paper 2. In this state, the paper 2 can pass through the roller pair 5g and is transported downstream without its progress being hindered by the shutter member 15.

[0037] The closed state is shown in Figure 2A, where the shutter member 15 rotates counterclockwise, blocking the portion that becomes the transport path 14 for the paper 2. In this state, the leading edge (downstream end) of the paper 2 comes into contact with the shutter member 15, so the paper 2 cannot pass through the roller pair 5g and is not transported downstream of the roller pair 5g.

[0038] Here, the shutter member 15 is biased by a predetermined force such that it remains closed when it is not subjected to any force from the paper 2. In other words, the shutter member 15 will not spontaneously open when the paper 2 is not in contact with it.

[0039] On the other hand, when the leading edge of the paper 2 comes into contact with the shutter member 15, as shown in Figure 2B, the shutter member 15 receives a force from the leading edge of the paper 2 equivalent to the transport force. Meanwhile, the paper 2 receives both the transport force and a resistive force from the shutter member 15, causing it to bend due to these forces.

[0040] As the paper 2 flexes more, the stiffness of the paper 2 increases the force exerted by the leading edge of the paper 2 on the shutter member 15. The magnitude of this force also depends on the type of paper 2. For example, if the paper 2 is stiff or thick, it will have more stiffness and exert a greater force on the shutter member 15. On the other hand, if the paper 2 is soft or thin, it will have less stiffness and exert a smaller force on the shutter member 15.

[0041] When the force exerted by the paper 2 on the shutter member 15 reaches a predetermined magnitude that exceeds the biasing force required to close the shutter member 15, the shutter member 15 rotates clockwise and enters the open state shown in Figure 2B. As a result, the paper 2 passes through the roller pair 5g and is transported downstream.

[0042] [Control component] Figure 3 is a schematic diagram showing an example of the configuration of the control member 17. Figure 3 shows the shutter member 15 and roller 16a in addition to the control member 17. In this embodiment, the control member 17 controls the magnitude of a predetermined force that causes the shutter member 15 to open. That is, it controls the biasing force that causes the shutter member 15 to close.

[0043] The control member 17 includes a motor 18 and a spring 19. One end of the spring 19 is connected to the motor 18, and the other end is connected to the left side of the shutter member 15. Note that Figure 3 is merely a schematic diagram, and the specific position of the shutter member 15 to which the spring 19 is connected is not limited. In reality, mechanisms such as a rack and pinion are arranged to connect the motor 18 and the spring 19, but these will be described later. Motor 18 corresponds to one embodiment of the drive source according to this technology.

[0044] In both states shown in Figures 3A and 3B, if the paper 2 does not come into contact with the shutter member 15, the elastic force of the spring 19 pulls the tip of the shutter member 15 to the left, maintaining the closed state. In other words, the spring 19 elastically biases the shutter member 15 so that it remains in the closed state.

[0045] The motor 18 can extend and contract the spring 19 by being driven. In Figure 3A, the spring 19 is compressed by the drive of the motor 18. In this state, the elastic force of the spring 19 is small, so the biasing force on the shutter member 15 is also small. On the other hand, in Figure 3B, the spring 19 is extended by the drive of the motor 18. In this state, the elastic force of the spring 19 is large, and the biasing force on the shutter member 15 is also large (arrow in Figure 3B).

[0046] In this way, the biasing force can be changed by driving the motor 18. In other words, it is possible to control the magnitude of the force required to open the shutter member 15.

[0047] Figure 4 is a perspective view showing a detailed configuration example of the control member 17. Figure 5 is a side view showing a detailed example of the configuration of the control member 17. In Figures 4A and 5A, the spring 19 is compressed, and the shutter member 15 is weakly biased. In Figures 4B and 5B, the spring 19 is extended, and the shutter member 15 is strongly biased. Also, in both Figure 4 and Figure 5, the shutter member 15 is in the closed position.

[0048] In this example, roller 16a consists of multiple rollers 22 (22a, 22b, ...), with a common shaft member 23 passing through their centers. Roller 16b also consists of multiple rollers 24 (24a, 24b, 24c, ...). In this example, for example, a common shaft member 25 passes through the centers of rollers 24a and 24b. When the shaft member 23 rotates due to the operation of a drive source (not shown), all the rollers 22 rotate together. Then, the rollers 24 that are in contact with the rollers 22 rotate. As a result, the paper 2 is sandwiched between the rollers 22 and 24 and transported.

[0049] The shutter member 15 is positioned to cover the shaft member 23, but is configured so that the shutter member 15 does not rotate in conjunction with the rotation of the shaft member 23. The shutter member 15 has contact members 26 on the front and back sides (negative and positive sides of the Y-axis) of the roller 22. In Figure 4, a contact member 26a is shown on the front side of roller 22a, a contact member 26b is shown on the front side of roller 22b, and a contact member 26c is shown on the back side of roller 22b. The lower end of the contact member 26 is the part that actually comes into contact with the paper 2.

[0050] The control member 17 includes a motor 18 and a spring 19, as well as pinions 27 (27a to 27d), a rack 28, and stoppers 29 (29a, 29b). In this example, the tip of the motor 18 is a gear. The pinion 27 is a two-stage gear consisting of a small gear and a large gear stacked on top of each other. The large gear of pinion 27a engages with the gear at the tip of the motor 18, the large gear of pinion 27b engages with the small gear of pinion 27a, the large gear of pinion 27c engages with the small gear of pinion 27b, and the large gear of pinion 27d engages with the small gear of pinion 27c.

[0051] The rack 28 is a plate-shaped member and has a toothed surface on its lower side that engages with the larger gear of the pinion 27d. The right end of the spring 19 is connected to the left end of the rack 28, and the left end of the spring 19 is connected to the lower front side of the shutter member 15. As a result, the elastic force of the spring 19 biases the shutter member 15 to rotate counterclockwise and close.

[0052] When the motor 18 is driven, the pinions 27a to 27d rotate in conjunction, and the rack 28 moves from side to side. This causes the spring 19 to expand and contract, changing its elastic force. In other words, the motor 18, pinions 27, and rack 28 function as an expansion and contraction mechanism that transmits the force of the motor 18 to the spring 19, thereby expanding and contracting the spring 19 and changing its elastic force.

[0053] The stopper 29 is a component that restricts the excessive movement of the rack 28. Specifically, a protrusion is provided on the rear side (positive side of the Y-axis) of the rack 28. When this protrusion contacts the left stopper 29a, the rack 28 cannot move any further to the left, and the spring 19 will not compress any further. Similarly, when the protrusion contacts the right stopper 29b, the rack 28 cannot move any further to the right, and the spring 19 will not extend any further. By providing the stopper 29, it is possible to prevent damage to other components caused by excessive expansion and contraction of the spring 19.

[0054] The method of connecting the motor 18 and the spring 19 by gears is not limited, and different types, numbers, and arrangements of gears may be used. Furthermore, the method of converting the driving force of the motor 18 into the expansion and contraction of the spring 19 is not limited, and any mechanism may be used. Also, the method of changing the biasing force of the shutter member 15 is not limited to the method using the motor 18 and the spring 19, and any method may be used. The specific configuration of the shutter member 15 is also not limited, and the shutter member 15 may be configured separately from the roller pair 5g if this technology is feasible.

[0055] [Correction of skew] This section describes a method for correcting the skew of paper 2 using this technology. As an example, we will describe a case where paper 2 is being transported parallel to the YZ plane in Figures 4 and 5, but is slightly rotated counterclockwise when viewed from the negative side in the X direction. In this case, a portion of the leading edge of paper 2 first comes into contact with the contact member 26a. Note that the biasing force of the shutter member 15 is set to be greater than the transport force of paper 2, so the shutter member 15 does not open at this point.

[0056] Next, the leading edge of the paper 2 comes into contact with the other contact members 26b, 26c, ... in sequence. The area near the leading edge of the paper 2 also curves, forming a loop. This loop is generally largest near contact member 26a, followed by 26b, 26c, ... in that order. This series of contacts and loop formations causes the leading edge of the paper 2 to become parallel to the Y direction, correcting the skew of the paper 2.

[0057] When the paper 2 forms a loop, the stiffness of the paper 2 generates a pressing force that attempts to open the shutter member 15. When the sum of this pressing force and the transport force exceeds the biasing force of the shutter member 15, the shutter member 15 opens, and the paper 2 passes over the roller pair 5g.

[0058] Here, for example, if the paper 2 is a thin, flimsy paper, increasing the biasing force of the shutter member 15 too much would cause damage to the leading edge of the paper 2. On the other hand, if the paper 2 is a thick, stiff paper, decreasing the biasing force too much would result in insufficient correction of the skew. To solve these problems, this technology makes it possible to change the biasing force of the shutter member 15 depending on the type of paper 2.

[0059] Specifically, first, the type of paper 2 is determined by multiple sensors installed in front of the shutter member 15. Alternatively, the type of paper 2 may be determined by obtaining the print settings entered by the user. Next, the correspondence between the type of paper 2 and the degree of expansion and contraction of the spring 19 is referred to, and the motor 18 is driven to achieve an appropriate degree of expansion and contraction. This makes it possible to set a biasing force suitable for the type of paper 2.

[0060] In the image forming apparatus 1 according to this embodiment, a shutter member 15 is provided that opens to allow the paper 2 to pass through when the leading edge of the paper 2 comes into contact with the shutter member 15 and receives a predetermined force from the paper 2. Control is also performed to change the predetermined force. This makes it possible to stably correct the skewness regardless of the type of paper 2.

[0061] Furthermore, this technology includes a spring 19 that uses elastic force to bias the shutter member 15 so that it is in a closed state. This makes it possible to adjust the biasing force with greater precision.

[0062] Furthermore, this technology incorporates an expansion / contraction mechanism that changes the elastic force by expanding and contracting the spring 19, and this expansion / contraction mechanism includes a motor 18, a pinion 27, and a rack 28. As a result, the large rotations of the motor 18 are converted into small movements of the rack 28, making it possible to precisely adjust the degree of expansion and contraction of the spring 19.

[0063] In this technology, a pair of rollers 5 is arranged in the transport path 14 to feed the paper 2 by gripping it, and a shutter member 15 is connected to the pair of rollers 5g, and the shutter member 15 is in an open or closed state so that the paper 2 can or cannot pass through the pair of rollers 5g. This makes it possible to transport the paper 2 stably.

[0064] Furthermore, in this technology, a line head 10 is provided, which is positioned downstream of the shutter member 15 and forms an image on the paper 2. As a result, the image is formed with the skew of the paper 2 corrected, making it possible to suppress problems such as the image being formed at an angle. [Explanation of symbols]

[0065] 1…Image forming apparatus 2… Paper 5... Roller vs. 10…Line head 14…Conveyor Route 15…Shutter components 17…Control component 18…motor 19...spring 22, 24... Roller 26... Contact member 27... Pinion 28... Rack

Claims

1. A shutter member provided along a sheet transport path, having an open state that allows the sheet to pass through, or a closed state that prevents the sheet from passing through, and which opens when the leading edge of the sheet comes into contact with the sheet and receives a force of a predetermined magnitude from the sheet; A control member capable of controlling the change of the predetermined size, An image forming apparatus comprising the following:

2. An image forming apparatus according to claim 1, The control member has a spring that elastically biases the shutter member so that the shutter member is in the closed state. Image forming apparatus.

3. An image forming apparatus according to claim 2, The control member has an expansion / contraction mechanism that changes the elastic force by expanding or contracting the spring. Image forming apparatus.

4. An image forming apparatus according to claim 3, The telescopic mechanism includes a drive source for extending and contracting the spring. Image forming apparatus.

5. An image forming apparatus according to claim 4, The telescopic mechanism includes at least one of a rack or pinion that transmits the force of the drive source to the spring. Image forming apparatus.

6. An image forming apparatus according to any one of claims 1 to 5, further comprising: It comprises a pair of rollers positioned on the aforementioned transport path, which feed out the sheet by gripping it, The shutter member is connected to the roller pair, and the open state is a state in which the sheet can pass through the roller pair, and the closed state is a state in which the sheet cannot pass through the roller pair. Image forming apparatus.

7. An image forming apparatus according to any one of claims 1 to 5, further comprising: It is positioned downstream of the shutter member in the transport path and comprises an image forming unit that forms an image on the sheet. Image forming apparatus.

Images