Image forming apparatus

Abstract

This invention provides an image forming apparatus. The image forming apparatus of one embodiment includes a sheet mounting section, a first roller, a second roller, and a control section. The sheet mounting section holds a sheet. The first roller applies a force in the conveying direction to the uppermost sheet of the sheet placed in the sheet mounting section by rotating in the forward direction. The second roller moves away from the first roller on the downstream side of the conveying direction. The second roller applies the force in the conveying direction to the uppermost sheet by rotating in the forward direction. The control section controls the rotation of the first roller and the second roller to perform a second main action after a first main action. The first main action is an action that rotates only the first roller in the forward direction. The second main action is an action that rotates both the first roller and the second roller in the forward direction.

Description

Technical Field

[0001] This embodiment relates to an image forming apparatus. Background Technology

[0002] The sheet feeding device of the image forming apparatus holds a stack of sheets formed by stacking multiple sheets. The sheet feeding device feeds the sheets of the stack one by one. However, depending on the type of sheet, the adhesion between the sheets constituting the stack can sometimes become stronger. In this case, overlapping may occur during sheet feeding. Summary of the Invention

[0003] The image forming apparatus of one embodiment includes: a sheet mounting section for mounting a sheet; a first roller that applies a force in the conveying direction to the uppermost sheet of the sheet mounted in the sheet mounting section by forward rotation; a second roller that moves downstream of the first roller in the conveying direction and applies a force in the conveying direction to the uppermost sheet by forward rotation; and a control unit that controls the rotation of the first roller and the second roller to perform a second main action after a first main action, wherein the first main action is an action that rotates only the first roller in the first roller and the second roller in the forward direction, and the second main action is an action that rotates both the first roller and the second roller in the forward direction. Attached Figure Description

[0004] Figure 1 This is a perspective view of an example configuration of the image forming apparatus according to the embodiment.

[0005] Figure 2 This is a diagram of the sheet material supply device.

[0006] Figure 3 This is a diagram illustrating the first mode of operation of the sheet feeding device.

[0007] Figure 4 This is a process diagram illustrating the operation of the sheet feeding device.

[0008] Figure 5 It is a process diagram that follows the previous diagram.

[0009] Figure 6 It is a process diagram that follows the previous diagram.

[0010] Figure 7 This is a diagram illustrating the second mode of operation of the sheet feeding device.

[0011] Figure 8 This is a process diagram illustrating the first example of the second preparatory action.

[0012] Figure 9 It is a process diagram that follows the previous diagram. Detailed Implementation

[0013] The image forming apparatus of this embodiment includes a sheet mounting section, a first roller, a second roller, and a control unit. The sheet mounting section mounts a sheet. The first roller applies a force in the conveying direction to the uppermost sheet mounted on the sheet mounting section by rotating in a forward direction. The second roller moves away from the first roller downstream in the conveying direction. The second roller applies a force in the conveying direction to the uppermost sheet by rotating in a forward direction. The control unit controls the rotation of the first roller and the second roller to perform a second main action after a first main action. The first main action is an action that rotates only the first roller in the forward direction. The second main action is an action that rotates both the first roller and the second roller in the forward direction.

[0014] The image forming apparatus of the embodiment will now be described with reference to the accompanying drawings. In each drawing, the same reference numerals are used for the same components. There are instances where the dimensions and shapes of the components are exaggerated or simplified.

[0015] like Figure 1 As shown, for example, the image forming apparatus 100 is a multifunction printer. The image forming apparatus 100 includes a display 110, a control panel 120, a printer unit 130, a sheet receiving unit 140, a control unit 150, and an image reading unit 200.

[0016] The image forming apparatus 100 forms an image on a sheet using a developing agent such as a toner. For example, the sheet is a sheet-shaped recording medium such as paper, label paper, resin sheet, postcard, or envelope.

[0017] The display 110 is an image display device such as a liquid crystal display or an organic EL (Electro Luminescence) display. The display 110 displays various information related to the image forming apparatus 100.

[0018] The control panel 120 has multiple buttons. The control panel 120 accepts user input. The control panel 120 outputs signals corresponding to the user's input to the control unit 150. It should be noted that the display 110 and the control panel 120 can also be configured as a single touch panel.

[0019] The printer unit 130 forms an image on a sheet based on image information generated by the image reading unit 200 or image information received via a communication path. For example, the printer unit 130 forms the image through the following process: The printer unit 130 forms an electrostatic latent image on a photosensitive drum based on the image information. The printer unit 130 forms a visible image by attaching a developer to the electrostatic latent image. The printer unit 130 is an image forming unit.

[0020] For example, the developer is a toning agent. The transfer section of the printer 130 transfers the visible image onto the sheet. The fixing section of the printer 130 fixes the visible image onto the sheet by heating and pressurizing it.

[0021] It should be noted that the printer unit 130 can be either a device for fixing toner images or an inkjet device.

[0022] The sheet receiving section 140 receives the sheet material for image formation in the printing section 130. The sheet receiving section 140 conveys the sheet material toward the printing section 130. The sheet receiving section 140 constitutes the sheet supply device 1. The sheet supply device 1 is also called a paper supply device.

[0023] The image reading unit 200 reads the image information of the object being read as the brightness of light. The image reading unit 200 records the read image information. The recorded image information can also be transmitted to other information processing devices via a network. The recorded image information can also be printed onto a sheet using the printing unit 130.

[0024] like Figure 2 As shown, the sheet feeding device 1 includes a sheet holding section 2, a first roller 3, a second roller 4, a paper feeding roller 5, and a separating roller 6.

[0025] The sheet mounting section 2 is capable of mounting a stack of sheets SS. The upper surface of the sheet mounting section 2 is the mounting surface 2a that supports the stack of sheets SS. The stack of sheets SS is composed of multiple sheets S stacked together.

[0026] An XYZ orthogonal coordinate system is used as the local coordinate system for the sheet placement section 2. The X direction is parallel to the placement surface 2a of the sheet placement section 2. The +X direction is the sheet conveying direction. The +X direction is also called the "downstream side". The Y direction is parallel to the placement surface 2a and orthogonal to the X direction. The Y direction is the width direction of the sheet S. The Z direction is perpendicular to the placement surface 2a of the sheet placement section 2. The +Z direction is the direction in which the sheet S is stacked on the placement surface 2a. For example, the +Z direction is the height direction. The +Z direction is upward. The position in the Z direction is also called the height position.

[0027] The first roller 3 and the second roller 4 have rotation axes parallel to the Y direction. The first roller 3 and the second roller 4 are capable of contacting the upper surface of the uppermost sheet S of the sheet stack SS placed in the sheet holding section 2. The uppermost sheet S is the uppermost sheet SA. The first roller 3 and the second roller 4 apply a force in the +X direction to the uppermost sheet SA through positive rotation. The first roller 3 and the second roller 4 convey the uppermost sheet SA in the +X direction. Figure 2In this configuration, the first roller 3 and the second roller 4 rotate counterclockwise. The first roller 3 and the second roller 4 are pickup rollers. The first roller 3 and the second roller 4 are also referred to as "rollers 3 and 4".

[0028] The first roller 3 can be displaced in the Z direction by means of the first lifting mechanism 7. For example, the first lifting mechanism 7 includes electronic equipment such as a solenoid and a mechanical linkage mechanism. The first lifting mechanism 7 may also include a support body that supports the first roller 3 and a drive source that displaces the first roller 3 in the Z direction. The first roller 3 can approach and move away from the sheet mounting section 2 by displacing in the Z direction.

[0029] The second roller 4 can be displaced in the Z direction by means of the second lifting mechanism 8. For example, the second lifting mechanism 8 includes electronic equipment such as a solenoid and a mechanical linkage mechanism. The second lifting mechanism 8 may also include a support body that supports the second roller 4 and a drive source that displaces the second roller 4 in the Z direction. The second roller 4 can approach and move away from the sheet mounting section 2 by displacing in the Z direction.

[0030] The second roller 4 exits the first roller 3 on the downstream side. Viewed from a direction parallel to the Z direction, the second roller 4 is located at the end in the +X direction near the sheet mounting section 2.

[0031] Preferably, the outer diameter of the first roller 3 is equal to the outer diameter of the second roller 4. If the outer diameter of the first roller 3 is equal to the outer diameter of the second roller 4, then when the rotation speed of rollers 3 and 4 is the same, the speed at which rollers 3 and 4 convey the sheet S becomes the same, thus making it easier to control the movement of rollers 3 and 4.

[0032] The first roller 3 and the second roller 4 are driven to rotate independently. Independent rotational drive is achieved by driving the first roller 3 and the second roller 4 to rotate using their respective dedicated drive sources. For example, the first roller 3 is driven to rotate using a first drive source. The second roller 4 is driven to rotate using a second drive source different from the first drive source. For example, both the first and second drive sources are electric motors. Because rollers 3 and 4 are driven to rotate using different drive sources, it becomes easier to set the rotational conditions of rollers 3 and 4 when their rotational conditions differ.

[0033] To independently rotate and drive the first roller 3 and the second roller 4, the drive mechanism shown below can also be used. The drive mechanism includes a drive source, a drive force transmission unit, a first clutch, and a second clutch. The drive source, via the drive force transmission unit, can drive one or both of the first roller 3 and the second roller 4. The first clutch can switch the connection and disconnection between the drive source and the first roller 3. In the connected state, the first clutch transmits the drive force of the drive source to the first roller 3. In the disconnected state, the first clutch does not transmit the drive force of the drive source to the first roller 3. The second clutch can switch the connection and disconnection between the drive source and the second roller 4. In the connected state, the second clutch transmits the drive force of the drive source to the second roller 4. In the disconnected state, the second clutch does not transmit the drive force of the drive source to the second roller 4. This drive mechanism is simple in construction because it uses only one drive source.

[0034] The feed roller 5 and the separation roller 6 have rotation axes parallel to the Y direction. The feed roller 5 is a drive roller that feeds the sheet S at the same speed as the pick-up roller 3. The feed roller 5 is driven by a drive source such as a motor.

[0035] The separating roller 6 is a driven roller that is linked to the paper feeding roller 5.

[0036] The paper feed roller 5 and the separating roller 6 clamp the sheet S fed from the sheet carrier section 2 in the roller gap for further conveying.

[0037] Control Unit 150 (Reference) Figure 1 The rotation of the first roller 3 and the second roller 4 is controlled by controlling the motion of the drive source. For example, the control unit 150 can control the driving and stopping of the first roller 3 and the second roller 4. The control unit 150 can control the rotational speed of the first roller 3 and the second roller 4.

[0038] The control unit 150 uses the first lifting mechanism 7 to determine the height position of the first roller 3, thereby adjusting the load applied to the sheet S by the first roller 3. The control unit 150 uses the second lifting mechanism 8 to determine the height position of the second roller 4, thereby adjusting the load applied to the sheet S by the second roller 4.

[0039] The load on the first roller 3 relative to the sheet S is set to F1 [N]. The coefficient of dynamic friction between the first roller 3 and the sheet S is set to μ. DP 1. The load on the second roller 4 relative to the sheet S is set to F2 [N]. The static friction coefficient of the second roller 4 relative to the sheet S is set to μ. SP 2[-]. Preferred load F1, dynamic friction coefficient μ DP 1. Load F2 and static friction coefficient μ SP 2 satisfies the following equation (1).

[0040] F1×μ DP 1 < F2 × μ SP 2(1)

[0041] Under the condition that equation (1) is satisfied, since the second roller 4 has a high function of restricting the movement of the sheet S, therefore, in the first main action A1 (refer to...) Figure 4 In this process, it becomes easier to form flexural deformation in the sheet S. For example, the dynamic friction coefficient and the static friction coefficient can be determined according to the method of JIS K7125 (1999).

[0042] The operation of the image forming apparatus 100 will now be explained.

[0043] like Figure 2 As shown, sheet placement section 2 places a stack of sheets SS. Figure 2 In the middle, the first roller 3 and the second roller 4 are in contact with the upper surface of the topmost sheet SA of the sheet stack SS.

[0044] Figure 3 This is a diagram illustrating the first mode of operation of the sheet feeding device 1.

[0045] like Figure 3 As shown, control unit 150 (refer to) Figure 1 These actions are performed in the following order: first main action A1, second main action A2, and third main action A3. The following is a description of the first main action A1, second main action A2, and third main action A3. Figure 3 In the diagram, the start of operation of the first roller 3 and the second roller 4 is indicated as "ON". The stop of operation of the first roller 3 and the second roller 4 is indicated as "OFF".

[0046] like Figure 4 As shown, in the first main action A1, the control unit 150 only causes the first roller 3 of the first roller 3 and the second roller 4 to rotate in the positive upward direction. In other words, the control unit 150 causes the first roller 3 to rotate in the positive upward direction and sets the second roller 4 to a stopped state.

[0047] The first roller 3 applies a downstream force to the uppermost sheet SA. The second roller 4, being stationary, restricts the movement of the uppermost sheet SA to the downstream side. The first roller 3 creates a flexure between the point of contact between itself and the second roller 4 on the uppermost sheet SA. This flexure is referred to as the flexure portion 9. The flexure portion 9 separates from the other sheets S. The adhesion between the flexure portion 9 and the other sheets S decreases.

[0048] The control unit 150 can adjust the timing of the first active action A1 according to the type of sheet S. Since the sheet S varies in thickness, surface condition, quality, mechanical properties, etc., depending on the type, the control unit 150 can adjust the timing of the first active action A1 according to the thickness, surface condition, quality, mechanical properties, etc. of the sheet S.

[0049] For example, since a thick sheet S (e.g., thick paper) is difficult to adhere tightly to other sheets S during stacking, the time of the first main action A1 can be shortened when using a thick sheet S. The time of the first main action A1 can also be zero. Since a sheet S with a large surface roughness is easier to adhere tightly to other sheets S during stacking, the time of the first main action A1 can be extended.

[0050] like Figure 3 As shown, the control unit 150 performs the second main action A2 after the first main action A1. Figure 5 As shown, in the second main operation A2, the control unit 150 causes both the first roller 3 and the second roller 4 to rotate upwards. The first roller 3 and the second roller 4 apply a downstream force to the uppermost sheet SA to convey the uppermost sheet SA to the downstream side. The first roller 3 and the second roller 4 guide the uppermost sheet SA between the feed roller 5 and the separation roller 6 (see reference). Figure 2 Preferably, the rotational speed of the first roller 3 is the same as the rotational speed of the second roller 4.

[0051] The first main action A1 and the second main action A2 are actions in which the second roller 4 starts rotating after the first roller 3 has started rotating.

[0052] like Figure 3 As shown, the control unit 150 performs the third main action A3 after the second main action A2. Figure 6 As shown, in the third main action A3, the control unit 150 only causes the second roller 4 of the first roller 3 and the second roller 4 to rotate in the positive direction. In other words, the control unit 150 stops the first roller 3 and causes the second roller 4 to rotate in the positive direction.

[0053] Preferably, the third main action A3 begins before the uppermost sheet SA leaves the first roller 3. Since the first roller 3 stops upon the start of the third main action A3, no force in the conveying direction is applied to the exposed second sheet S, thus allowing the second sheet S to be held in a predetermined position.

[0054] The second roller 4 applies a force to the uppermost sheet SA towards the downstream side and conveys the uppermost sheet SA to the downstream side. The control unit 150 stops the rotation of the second roller 4 after the uppermost sheet SA leaves the second roller 4.

[0055] like Figure 2 As shown, the paper feed roller 5 and the separating roller 6 clamp the sheet S in the roller gap and further convey the sheet S. The sheet S goes to the printer section 130 (see reference). Figure 1 ).

[0056] In the image forming apparatus 100, during the first main operation A1, the uppermost sheet SA flexes. Since the flexed portion of the uppermost sheet SA (flexed portion 9) separates from the other sheets S, the adhesion between the uppermost sheet SA and the other sheets S is reduced. Because the adhesion between the uppermost sheet SA and the other sheets S is reduced, overlapping transport of the sheets S can be suppressed.

[0057] exist Figure 3 In the illustrated manner, although the control unit 150 stops the first roller 3 in the third main action A3, it may also choose not to stop the first roller 3. Alternatively, in the third main action A3, the control unit 150 may raise the third roller 3 while maintaining the rotational drive of the first roller 3, causing it to leave the uppermost sheet SA.

[0058] Figure 7 This is a diagram illustrating the second mode of operation of the sheet feeding device 1.

[0059] like Figure 7 As shown, in the second embodiment, the control unit 150 (refer to...) Figure 1 Before the first main action A1, at least one set of first preparatory actions A4 and second preparatory actions A5 shall be performed. Figure 7 In the example shown, the control unit 150 performs two sets of first preparatory actions A4 and second preparatory actions A5 before the first main action A1. In other words, after performing these actions in the order of first preparatory action A4, second preparatory action A5, first preparatory action A4, and second preparatory action A5, the control unit 150 performs the first main action A1, the second main action A2, and the third main action A3. The first preparatory action A4 and the second preparatory action A5 will be explained below.

[0060] like Figure 8 As shown, in the first preparatory action A4, the control unit 150 only causes the first roller 3 of the first roller 3 and the second roller 4 to rotate in the positive upward direction. Figure 7 In this diagram, upward rotation is denoted as "forward rotation". The first roller 3 applies a downstream force to the uppermost sheet SA. The second roller 4, being stationary, restricts the movement of the uppermost sheet SA to the downstream side. The first roller 3 forms a flexural portion 9 on the uppermost sheet SA. The adhesion between the flexural portion 9 and the other sheets S is reduced.

[0061] like Figure 7 As shown, the control unit 150 can set the timing of the first preparatory action A4 according to the type of sheet S. For example, the control unit 150 can set the timing of the first preparatory action A4 according to the thickness, surface condition, quality, mechanical properties, etc. of the sheet S.

[0062] The control unit 150 performs a second preparatory action A5 after the first preparatory action A4. Examples of the second preparatory action A5 include a first example and a second example.

[0063] like Figure 9 As shown, in the first example, the control unit 150 only causes the first roller 3 of the first roller 3 and the second roller 4 to rotate in the opposite direction. "Reverse" means the direction opposite to the forward direction. Figure 7 In this context, the reverse rotation is recorded as "reverse rotation". Because the first roller 3 moves the uppermost sheet SA upstream, the deflection of the uppermost sheet SA is eliminated.

[0064] In the second example, the control unit 150 reduces the load on the uppermost sheet SA only for the first roller 3 of the first roller 3 and the second roller 4. To reduce the load on the first roller 3, the height position of the first roller 3 can be adjusted by the first lifting mechanism 7. Since the load on the first roller 3 is reduced, the restriction of the first roller 3 is weakened, so a portion of the uppermost sheet SA can move to the upstream side, and the deflection is eliminated.

[0065] like Figure 7 As shown, the control unit 150 performs the first preparatory action A4 and the second preparatory action A5 for the second time.

[0066] Next, the control unit 150 performs these actions in the order of the first main action A1, the second main action A2, and the third main action A3 (see reference). Figures 3-5 ).

[0067] In the image forming apparatus 100, since at least one set of first preparatory actions A4 and second preparatory actions A5 are performed before the first main action A1, the adhesion force between the uppermost sheet SA and other sheets S can be further reduced. Because the adhesion force between the uppermost sheet SA and other sheets S can be reduced, overlapping transport of the sheets S can be suppressed.

[0068] exist Figure 7 In the example shown, two sets of first preparatory actions A4 and second preparatory actions A5 are performed; however, there is no particular limitation on the number of sets of first preparatory actions A4 and second preparatory actions A5. The number of sets of first preparatory actions A4 and second preparatory actions A5 can be one or more (any number above two).

[0069] The control unit 150 can set the number of first preparatory actions A4 and second preparatory actions A5 according to the type of sheet S. For example, when sheet S is of type 1, the number of first preparatory actions A4 and second preparatory actions A5 can be set as the first number. When sheet S is of type 2, the number of first preparatory actions A4 and second preparatory actions A5 can be set as the second number. The second type is different from the first type. The second number is different from the first number. The control unit 150 can set the number of first preparatory actions A4 and second preparatory actions A5 according to the thickness, surface condition, quality, mechanical properties, etc. of sheet S.

[0070] According to at least one embodiment described above, in the first main action A1, the uppermost sheet SA flexes. Since the flexed portion of the uppermost sheet SA separates from the other sheets S, the adhesion between the uppermost sheet SA and the other sheets S is reduced. Because the adhesion between the uppermost sheet SA and the other sheets S can be reduced, overlapping conveying of the sheets S can be suppressed.

[0071] While several embodiments have been described, these embodiments are merely illustrative and not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and likewise within the scope of the invention as described in the claims and its equivalents.

Claims

1. An image forming apparatus comprising: Sheet placement section, for placing sheet materials; The first roller applies a force in the conveying direction to the uppermost sheet of the sheet placed in the sheet carrier section by rotating in the forward direction; The second roller exits the first roller on the downstream side of the conveying direction and applies a force in the conveying direction to the uppermost sheet by rotating in the forward direction; The control unit controls the rotation of the first roller and the second roller to perform a second main action after the first main action. The first main action is an action that causes only the first roller of the first roller and the second roller to rotate in the positive direction, and the second main action is an action that causes both the first roller and the second roller to rotate in the positive direction. A first lifting mechanism displaces the first roller in a first direction, the first direction being perpendicular to the mounting surface of the sheet mounting portion. as well as The second lifting mechanism displaces the second roller in the first direction. The control unit uses the first lifting mechanism to adjust the load applied to the sheet by the first roller, and the control unit uses the second lifting mechanism to adjust the load applied to the sheet by the second roller. a load F1 of the first roller pair on the sheet, a dynamic friction coefficient μ of the first roller pair on the sheet DP 1. a load F2 of the second roller pair on the sheet, and a static friction coefficient μ of the second roller pair on the sheet SP 2. the following equation is satisfied: F1 x μ DP 1 < F2 x μ SP 2.

2. The image forming apparatus according to claim 1, wherein, Before the first main action, the control unit performs at least one set of first preparatory actions and a second preparatory action. In the first preparatory action, only the first roller of the first roller and the second roller are rotated in the positive direction. The second preparatory action, following the first preparatory action, causes only the first roller of the first roller and the second roller to rotate in the opposite direction to the forward direction.

3. The image forming apparatus according to claim 1, wherein, Before the first main action, the control unit performs at least one set of first preparatory actions and a second preparatory action. The first preparatory action only causes the first roller of the first roller and the second roller to rotate in the positive direction. The second preparatory action follows the first preparatory action and reduces the load on the sheet only for the first roller of the first roller and the second roller.

4. The image forming apparatus according to claim 1, wherein, The control unit can adjust the timing of the first active action according to the type of sheet.

5. The image forming apparatus according to claim 2, wherein, The control unit can adjust the timing of the first preparatory action according to the type of sheet.

6. The image forming apparatus according to claim 2, wherein, When the sheet is of the first type, the control unit sets the number of the first preparatory action and the second preparatory action to a first number; when the sheet is of the second type, the control unit sets the number of the first preparatory action and the second preparatory action to a second number.

7. The image forming apparatus according to claim 1, wherein, After the second main action, the control unit performs a third main action that rotates only the second roller of the first roller and the second roller in the positive direction.

8. The image forming apparatus according to claim 7, wherein, Before the sheet leaves the first roller via the second main action, the control unit begins the third main action.

9. The image forming apparatus according to claim 1, wherein, The first roller rotates via a first drive source. The second roller rotates via a second drive source that is different from the first drive source.

Images