Sheet binding device and image forming apparatus

A sheet binding device includes a first binding unit that performs a first binding process of binding a sheet bundle having a first thickness or less without using a staple, and a second binding unit that performs a second binding process of binding the sheet bundle having a second thickness or less exceeding the first thickness using a staple, the first binding process by the first binding device is preferentially executed when the thickness of the sheet bundle is the first thickness or less, and the second binding process by the second binding unit is executed when the thickness of the sheet bundle exceeds the first thickness and is equal to or less than the second thickness.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2019-211439 filed on Nov. 22, 2019, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to a sheet binding device capable of performing two types of binding processing and an image forming apparatus.

Some image forming apparatuses include a sheet binding device capable of selectively performing, between binding processing without using a staple and binding processing using a staple, with respect to the sheet after the image formation is performed.

Generally, the staple binding processing can bind a larger number of sheets than the staple-free binding processing.

However, the number of sheets that can be stapled by the staple-free binding processing and the staple binding processing varies depending on the thickness of the sheet.

Therefore, it is known that the number of sheets that can be stapled by the staple-free binding processing is set for each type of sheet, and whether or not to execute the staple-free binding processing is controlled according to the type of sheet and the number of sheets to be processed.

SUMMARY

A sheet binding device according to an aspect of the present disclosure includes a processing tray, a first binding unit, a second binding unit, a thickness detection unit, and a binding control unit. The processing tray is stacked with a sheet bundle formed by stacking a predetermined number of sheets to be carried in. The first binding unit performs a first binding process for binding the sheet bundle having a thickness of equal to or less than a first thickness without using a staple. The second binding unit can perform a second binding process for binding the sheet bundle having a thickness of equal to or less than a second thickness exceeding the first thickness, using a staple. The first thickness detection unit detects a first state in which a thickness of the sheet bundle exceeds the first thickness. The number counting unit counts the number of sheets of the sheet bundle. When the number of sheets counted by the number counting unit reaches a designated number of sheets, the binding control unit executes the first binding process by the first binding unit when the first thickness detection unit does not detect the first state, and executes the second binding process by the second binding unit when the first thickness detection unit detects the first state.

DETAILED DESCRIPTION

It should be noted that the following embodiments are merely examples of the present disclosure, and do not limit the technical scope of the present disclosure.

[Configuration of Image Forming Apparatus100]

As shown inFIG. 1, a sheet binding device3according to the embodiment constitutes a part of an image forming apparatus100. The image forming apparatus100includes a main body unit1and a post-processing unit2.

The post-processing unit2is connected to the main body unit1.

The main body unit1includes a sheet supply unit11, a first sheet conveyance device12, a first conveyance path13, and a printing apparatus14, which are provided in a main body chassis10.

Further, the main body unit1also includes a control device8, an operation device801, a display device802, and the like.

The operation device801is a device that accepts an operation of a user. For example, the operation device801includes one or both of a touch panel and an operation button.

The display device802displays a menu screen related to an operation on the operation device801or other information.

The first sheet conveyance device12conveys the sheets9accommodated in the sheet supply unit11along the first conveyance path13one by one. a printing apparatus14executes printing processing on the sheet9conveyed along the first conveyance path13.

For example, the printing apparatus14executes the printing processing of the inkjet system. Note that the printing apparatus14may be a device that executes printing processing of the electrophotographic method or the other method.

The first sheet conveyance device12conveys the sheet9on which an image is formed from an outlet of the first conveyance path13toward the post-processing unit2.

The post-processing unit2includes a second conveyance path21, a second sheet conveyance device22and a sheet binding device3provided in a post-processing housing20, and a discharge tray23provided outside the post-processing housing20.

The sheet9sent from the main body unit1to the post-processing unit2is carried into the second conveyance path21. The second sheet conveyance device22includes a plurality of pairs of conveyance rollers221that convey the sheet9along the second conveyance path21.

Further, the second sheet conveyance device22includes a sending roller pair222that feeds the sheet9to the sheet binding device3.

In the example shown inFIG. 1, the post-processing unit2further includes a sheet folding device4provided in the post-processing housing20. The sheet folding device4performs a folding process on the sheet9.

The sheet binding device3performs a first binding process or a second binding process on a plurality of sheets9on which an image has been formed by the printing apparatus14. The first binding process is staple-free binding processing for binding a plurality of sheets9without using a staple. The second binding process is staple binding processing for binding a plurality of sheets9by using a staple. Details of the sheet binding device3will be described later.

The control device8controls the devices included in the main body unit1and the post-processing unit2. As shown inFIG. 2, the control device8includes a central processing unit (CPU)81and a peripheral device such as a random access memory (RAM)82, a second storage device83, and a signal interface84.

A CPU81is a processor that executes various types of data processing and control by executing a computer program. A RAM82is a computer-readable volatile storage device. The RAM82temporarily stores the computer program executed by the CPU81and a data to be referred to in the process of the CPU81executing the various types of processing.

The second storage device83is a computer-readable non-volatile storage device. The second storage device83is capable of storing and updating the computer program and various types of data. For example, one or both of a flash memory or a hard disk drive may be employed as the second storage device83.

The signal interface84converts signals output from various sensors included in the image forming apparatus100into digital data, and transmits the converted digital data to the CPU81. Further, the signal interface84transmits the control signal output by the CPU81to devices to be controlled.

The CPU81of the control device8includes a plurality of processing modules that are implemented by executing the computer program. The plurality of processing modules include a main control unit8a, a print control unit8b, a binding control unit8c, and the like.

The main control unit8aexecutes a start control for starting the various types of processing in response to the operation performed on the operation device801and the control of the display device802.

The print control unit8bcontrols the printing apparatus14.

For example, the print control unit8bcauses the printing apparatus14to execute the printing processing.

The binding control unit8ccontrols the sheet binding device3. In the present embodiment, the binding control unit8cconstitutes a part of the sheet binding device3. For example, the binding control unit8ccauses the sheet binding device3to execute one of the processes specified in the first binding process and the second binding process.

The second binding process can bind a larger number of sheets9than the first binding process. However, the upper limit number of sheets9corresponding to each of the first binding process and the second binding process varies depending on a thickness of each of sheets9to be processed.

In some cases, the user may want to perform the first binding process preferentially, and to perform the second binding process only when the first binding process is impossible.

Moreover, setting the upper limit number of sheets for binding processing for each type of sheets9and setting the type of all sheets9that may be subject to processing is a complicated task for the user.

The sheet binding device3has a configuration in which the user can perform the first binding process without using a staple preferentially over the second binding process using a staple without the need for the user to consider the thickness of the sheet.

[Configuration of Sheet Binding Device3]

As shown inFIG. 3, the sheet binding device3includes a processing tray31, an end supporting portion32, a first binding unit33a, a second binding unit33b, a binding state switching mechanism (switching mechanism)33c, an aligning rotation mechanism34, a sheet discharge mechanism35, and a thickness sensor30.

The processing tray31is disposed so as to be inclined, and a plurality of sheets9fed out from above one by one by the pair of sending rollers222are stacked on the processing tray31. In the following description, a plurality of sheets9stacked on the processing tray31are referred to as a stacked sheets9A (seeFIGS. 3,5,6). Note that the stacked sheets9A are a sheet bundle composed of a plurality of sheets9.

The end supporting portion32is erected in a portion close to an upstream end of the processing tray31in a sheet feed direction, and supports the rear end of the sheets9on the processing tray31.

The aligning unit34includes an aligning member341and a movable support member342. The movable support member342supports the aligning member341so as to be displaceable between a contact position in contact with the upper surface of the sheets9on the processing tray31and a retracting position away from the sheets9.

Each time one sheet9is fed from above onto the processing tray31, the aligning rotation mechanism34displaces the aligning member341from the retracting position to the contact position, and then displaces from the contact position to the retracting position.

The aligning member341rotates while being in contact with the upper surface of the sheets9on the processing tray31at the contact position, thereby urging the sheets9toward the end supporting portion32. For example, the aligning member341is a roller on which an elastic layer such as a rubber layer having a large friction coefficient with respect to the sheet9is formed in the surface layer.

The aligning member341biases the sheets9on the processing tray31toward the end supporting portion32, so that the rear ends of the sheets9in the stacked sheet9A are aligned with the position of the end supporting portion32.

It is also conceivable that the aligning member341is a plate-shaped elastic member protruding from a rotating shaft to be rotationally driven. In this case, the aligning member341makes contact with the upper surface of the sheets9so as to sweep the sheets9obliquely downward, every time the aligning member341rotates for one rotation. As a result, the aligning member341urges the sheets9toward the end supporting portion32each time the aligning member341rotates for one rotation.

The first binding unit33aand the second binding unit33bare disposed at positions closer to the end of the processing tray31on the side of the end supporting portion32.

The first binding unit33aperforms the first binding process without using a staple on the lower edge portion of the stacked sheet9A. The second binding unit33bperforms the second binding process using a staple on the lower edge portion of the stacked sheet9A.

In the second binding process, the second binding unit33bcan bind a stacked sheet9A having a thickness greater than that of the first binding process.

The binding state switching mechanism33cmoves the first binding unit33aand the second binding unit33bto selectively switch the first binding unit33aand the second binding unit33bto one of a first standby state and a second standby state.

The first standby state is a state in which the first binding process by the first binding unit33acan be performed. The second standby state is a state in which the second binding process by the second binding unit33bcan be performed.

The binding state switching mechanism33cmoves one of the first binding unit33aand the second binding unit33bto the operating position, and moves the other one of the first binding unit33aand the second binding unit33bto a retracting position that does not interfere with the target binding device. A state in which the first binding unit33ais arranged at the operating position is the first standby state, and a state in which the second binding unit33bis arranged at the operating position is the second standby state.

For example, the first binding unit33ais supported so as to be movable between a first operating position corresponding to the corner portion of the stacked sheets9A and a retracting position away from the edge of the stacked sheets9A.

On the other hand, the second binding unit33bis supported to be movable to the second operating position and the third operating position along the width direction of the processing tray31, and also to be movable to the first operating position by being rotated by a predetermined angle at the end of the processing tray31.

The binding state switching mechanism33cmoves the second binding unit33bto the second operating position or the third operating position that does not interfere with the first binding unit33a, and then moves the first binding unit33ato the first operating position. As a result, the first binding unit33aand the second binding unit33bare shifted to the first standby state.

On the other hand, the binding state switching mechanism33cmoves the first binding unit33ato the retracting position, and then moves the second binding unit33bto the first operating position, the second operating position, or the third operating position. As a result, the first binding unit33aand the second binding unit33bare shifted to the second standby state.

The sheet discharge mechanism35executes a sheet discharge process for discharging the stacked sheets9A onto the discharge tray23. Normally, the sheet discharge mechanism35discharges the stacked sheets9A on which the first binding process or the second binding process has been performed, onto the discharge tray23. Note that the sheet discharge mechanism35can also discharge the stacked sheets9A, which has not been subjected to any of the first binding process and the second binding process, onto the discharge tray23.

In the example illustrated inFIG. 3, the sheet discharge mechanism35includes an upper discharge roller351, a lower discharge roller352, and a movable support mechanism353. The lower discharge roller352is disposed on an extension line obliquely above the processing tray31.

The movable support mechanism353supports the upper discharge roller351so as to come into contact with and separated from the lower discharge roller352. The movable support mechanism353holds the upper discharge roller351at a retracting position separated from the stacked sheet9A in the initial state.

Further, when discharging the stacked sheets9A onto the discharge tray23, the movable support mechanism353displaces the upper discharge roller351from the retracting position to the discharge position. The discharge position is a position of the upper discharge roller351that sandwiches the stacked sheet9A between the discharge position and the lower discharge roller352.

When the upper discharge roller351rotates at the discharge position, the stacked sheets9A are discharged from the processing tray31to the discharge tray23with the upper discharge roller351and the lower discharge roller352.

When the number of the stacked sheets9A reaches the designated number of sheets, the binding control unit8ccauses one of the first binding unit33aand the second binding unit33bto execute one of the first binding process and the second binding process. Further, the binding control unit8ccauses the sheet discharge mechanism35to execute the sheet discharge processing.

For example, the number counting unit8ecounts the number of sheets of the stacked sheet9A. The print control unit8bsets the number of prints input to the operation device801as the designated number of sheets.

When the number of the stacked sheets9A counted by the number-of-sheets counting unit8ereaches the designated number of sheets, the binding control unit8cexecutes one of the first binding process by the first binding unit33aand the second binding process by the second binding unit33b, which has been selected in advance, and then executes the sheet discharge processing by the sheet discharge mechanism35.

The thickness sensor30detects a first over state in which the thickness of the stacked sheets9A exceeds the first thickness or a second over state in which the thickness exceeds the second thickness.

The first thickness is a maximum thickness of the stacked sheet9A capable of being subjected to the first binding process by the first binding unit33a. The second thickness is a maximum thickness of the stacked sheet9A capable of being subjected to the second binding process by the second binding unit33b.

The detection position of the thickness sensor30is located at a portion between the aligning member341and the end supporting portion32in the stacked sheet9A.

The thickness sensor30includes a swing member36and an object sensor37. The swing member36is swingably supported above the processing tray31.

As shown inFIG. 4, the swing member36includes a shaft portion361, an arm portion362, a detected portion363, and a balancer365.

The shaft portion361is rotatably supported by a frame of the post-processing unit2. Accordingly, the swing member36is swingable about the shaft portion361.

The arm portion362is formed so as to extend downward from the shaft portion361. The distal end portion of the arm portion362is in contact with the detection position between the aligning member341and the end supporting portion32on the upper surface of the stacked sheet9A, and thus swings up and down in accordance with the thickness of the stacked sheets9A.

The detected portion363is formed so as to extend from the shaft portion361and displaced in conjunction with the swinging of the arm portion362.

The first sensor37aand the second sensor37bdetect the detected portion363in a part of the displacement range of the detected portion363. In the present embodiment, each of the first sensor37aand the second sensor37bis a transmissive-type photosensor

The first sensor37aand the second sensor37bmay be a reflection-type photosensor, a contact-type micro-switch, and the like.

The first sensor37aand the second sensor37bmay be a reflection-type photosensor, a contact-type micro-switch, and the like.

The first sensor37adetects the first over state in which the thickness of the stacked sheet9A exceeds the first thickness by detecting the detected portion363in the first position.FIG. 5shows a state in which the thickness sensor30detects the first over state.

On the other hand, the second sensor37bdetects that the distal end portion of the arm portion362has been displaced to a position corresponding to the second thickness by detecting the detected portion363at the second position in the displacement range of the detected portion363.FIG. 6shows a state in which the thickness sensor30detects the second thickness.

In the present embodiment, the CPU81of the control device8further includes a thickness determination unit8das one of the plurality of processing modules. The thickness determination unit8ddetermines the thickness of the stacked sheet9A based on the detection result of the object detected by the object sensor37.

Specifically, the thickness determination unit8dfirst determines that the thickness sensor30detects a reference state when the first sensor37aand the second sensor37bdo not detect the detected portion363. The reference state is a state in which the thickness of the stacked sheet9A is equal to or less than the first thickness.

Further, the thickness determination unit8ddetermines that the thickness sensor30detects the first over state when the first sensor37adetects the detected portion363and the second sensor37bdoes not detect the detected portion363.

Further, the thickness determination unit8ddetermines that the thickness sensor30detects the second over state when the first sensor37adoes not detect the detected portion363and the second sensor37bdetects the detected portion363.

When determining that the thickness sensor30detects the second over state, the thickness determination unit8dalso determines that the first over state is detected.

In addition, the thickness determination unit8ddetermines that the thickness sensor30is in an error state when the detection result of the object sensor37indicates a state other than the above-described state.

The thickness sensor30and the thickness determination unit8dare examples of a first thickness detection unit that detects the first over state and a second thickness detection unit that detects the second over state.

Generally, the edge portion to which the staple processing is performed on the sheets9are often a portion in which an image is formed with a margin portion or with a relatively small amount of ink. In addition, the sheets9may be curved in some cases. Therefore, when the state of the thickness of the portion of the stacked sheets9A away from the edge portion is detected, there is a possibility that a false detection occurs in which the state of the thickness of the portion subjected to the first binding process or the second binding process and the detection result are different from each other.

On the other hand, in the thickness sensor30, the distal end portion of the arm portion362comes into contact with the vicinity of the edge portion of the stacked sheets9A, on which the first binding process or the second binding process is performed. Therefore, the erroneous detection is less likely to occur.

In the present embodiment, the binding control unit8cperforms the sheet binding control in the procedure illustrated inFIG. 7, for example, when the staple-free binding priority mode is set to the operation mode of the sheet binding device3in advance.

The staple-free binding priority mode is an operation mode in which the first binding process is performed preferentially, and the second binding process is executed in a case where the first binding process is not possible.

[Sheet Binding Control in Staple-Free Binding Priority Mode]

Hereinafter, an example of the procedure of the sheet binding control executed when the staple-free binding priority mode is set will be described with reference to the flowchart illustrated inFIG. 7.

The binding control unit8cstarts the sheet binding control illustrated inFIG. 7when the print processing is started in a situation in which the staple-free binding priority mode is set.

In the following description, S1, S2, . . . represent identification signs of a plurality of steps in the sheet binding control.

In step S1, the binding control unit8ccontrols the binding state switching mechanism33cto transition the first binding unit33aand the second binding unit33bto the first standby state. Accordingly, the first binding unit33acan promptly execute the first binding process. Thereafter, the binding control unit8cproceeds to step S2.

In step S2, the binding control unit8cdetermines whether or not a sheet9is newly sent onto the processing tray31. Then, upon determining that the sheet9is newly sent onto the processing tray31, the binding control unit8cproceeds to step S3.

For example, the binding control unit8cdetermines that the sheet9is newly sent onto the processing tray31when a predetermined time has elapsed since the detection of the sheet9by a sensor that detects the sheet9in the first conveyance path13or the second conveyance path21.

In step S3, the binding control unit8cdetermines whether the number of the stacked sheets9A has reached the designated number of sheets.

When the binding control unit8cdetermines that the number of stacked sheets9A has reached the designated number of sheets, the binding control unit8cproceeds to step S6. Otherwise, the binding control unit8ccauses the processing to proceed to step S4.

In step S4, when the first over state is detected by the thickness sensor30and the thickness determination unit8d, the binding control unit8cproceeds to step S5. Otherwise, the binding control unit8cskips the step S7and repeats the process from step S2.

In step S5, the binding control unit8ccontrols the binding state switching mechanism33cto shift the first binding unit33aand the second binding unit33bto the second standby state. Accordingly, the second binding unit33bcan promptly execute the second binding process. Thereafter, the binding control unit8cproceeds to step S1.

As described above, the binding control unit8ccontrols the binding state switching mechanism33cto shift the first binding unit33aand the second binding unit33bto the first standby state before the first sheet9is sent to the processing tray31(step S1).

Further, when the first over state is detected before the number of sheets9A reaches the designated number of sheets, the binding control unit8ccontrols the binding state switching mechanism33cto shift the first binding unit33aand the second binding unit33bto the second standby state (step S5).

In step S6, the binding control unit8cproceeds to step S7when the thickness sensor30and the thickness determination unit8ddetect the first over state. Otherwise, the binding control unit8cproceeds to step S8.

In step S7, the binding control unit8cproceeds to step S12when the thickness sensor30and the thickness determination unit8ddetect the second over state. Otherwise, the binding control unit8cproceeds to step S9.

In step S8, the binding control unit8ccauses the first binding unit33ato execute the first binding process, and subsequently, proceeds to step S12.

Note that, since the process in step S1is previously executed, the first binding unit33aand the second binding unit33bare already in the first standby state, in step S8. Therefore, when the number of the stacked sheets9A reaches the designated number of sheets, the first binding process is promptly performed in step S8.

In step S9, when the first binding unit and the second binding unit are in the first standby state, the binding control unit8cproceeds to step S10. Otherwise, the binding control unit8cskips the process of step S10and proceeds to step S11.

In step S10, the binding control unit8ccontrols the binding state switching mechanism33cto shift the first binding unit33aand the second binding unit33bto the second standby state. Subsequently, the binding control unit8cproceeds to step S11.

In step S11, the binding control unit8ccauses the second binding unit33bto execute the second binding process, and subsequently, proceeds to step S12.

Note that when the first over state is detected before the number of the stacked sheets9A reaches the designated number of sheets, in step S9, the first binding unit33aand the second binding unit33bare already shifted to the second standby state by the processing of step S5. In this case, when the number of the stacked sheets9A reaches the designated number of sheets, the process S10is skipped, and the second binding process is promptly executed in the process S11.

In step S12, the binding control unit8ccauses the sheet discharge mechanism35to execute the sheet discharge processing. Thereafter, the binding control unit8cproceeds to step S13.

In step S13, the binding control unit8cends the binding control when the print processing is completed, and repeats the processing from step S1when the printing processing is not completed.

In the binding control, the processes in steps S6to S11are examples of a binding selection control. The binding selection control includes a control of selecting processing to be adopted from among the first binding process and the second binding process in accordance with a detection state of the thickness of the predetermined portion in the stacked sheet9A, and of causing the first binding unit33aor the second binding unit33bto execute the selected processing.

That is, when the number of stacked sheets9A reaches the designated number of sheets, the binding control unit8cexecutes the binding selection control in steps S6to S11, and then causes the sheet discharge mechanism35to execute the sheet discharge process in step S12.

In the binding selection control of steps S6to S11, the binding control unit8ccauses the first binding unit33ato perform the first binding process when the first over state is not detected (step S8), and causes the second binding unit33bto perform the second binding process when the second over state is detected (step S11).

More specifically, in the binding selection control in steps S6to S11, the binding control unit8cperforms the processing by distinguishing a first situation, a second situation, and a third situation described below.

The first situation is a situation in which the first over state and the second over state are not detected.

In the first situation, the binding control unit8ccauses the first binding unit33ato execute the first binding process (step S8).

The second situation is a situation in which the first over state has been detected and the second over state has not been detected. In the second situation, the binding control unit8ccauses the second binding unit33bto execute the second binding process (step S11).

The third situation is a situation in which the second over state is detected. In the third situation, the binding control unit8cdoes not operate any of the first binding unit33aand the second binding unit33b(Yes in step S7).

When the sheet binding device3is adopted, it is unnecessary to perform complicated operations such as an operation of setting the upper limit number of sheets for the first binding process for each type of the sheet9and an operation of setting the kinds of all sheets9that may be processed.

Therefore, by executing the binding control illustrated inFIG. 7, the sheet binding device3can perform the staple-free binding processing more preferentially than the staple binding processing without requiring complicated operation of the user.

FIRST APPLICATION EXAMPLE

In the first application example of the sheet binding device3, it is conceivable that the binding control unit8cexecutes the following confirmation process before the processing in step S11inFIG. 7is performed. The confirmation process is executed when the first over state is detected when the number of stacked sheets9A reaches the designated number of sheets.

The confirmation process is a process of notifying a predetermined inquiry and determining whether or not a permission for the inquiry notification is input. For example, the binding control unit8coutputs the inquiry notification on the display device802, and determines the input status of the permission through the operation device801.

The binding control unit8cin the application example causes the first binding unit33ato execute the first binding process in a case where the first over state is not detected in the binding selection control (step S8). This is the same as described above.

In addition, the binding control unit8cin the application example notifies the inquiry before the processing in step S11in the binding selection control, causes the second binding unit33bto execute the second binding process when the permission for the inquiry is input (step S10), and when the permission is not input, the binding control unit8cskips the process in step S11and the processing proceeds to step S12.

That is, in the application example, the binding control unit8cdoes not operate any of the first binding unit33aand the second binding unit33bwhen the permission is not input.

When the present application example is employed, the same effect as in the case where the sheet binding device3is employed can be obtained.

SECOND APPLICATION EXAMPLE

The thickness sensor30may be a transmissive-type photosensor including a light emitting portion and a light receiving portion that oppose each other in the width direction of the processing tray31. In this case, the swing member36is omitted.

In the present application example, for example, the light emitting portion and the light receiving portion of the first photosensor detect the sheet9at a position spaced apart from the upper surface of the processing tray31by a distance corresponding to the first upper limit thickness.

Further, in the present application example, the light emitting portion and the light receiving portion of the second photosensor detect the sheet9at a position spaced apart from the upper surface of the processing tray31by a distance corresponding to the second upper limit thickness.