SHEET FEEDING DEVICE

Abstract

A sheet feeding device includes a pick-up roller, a sensor, and a sheet feeding controller. The pick-up roller draws out a plurality of sheets one by one from a sheet table on which the plurality of sheets are loaded. The sensor detects presence or absence of the sheet. The sheet feeding controller controls drive to raise the pick-up roller on the basis of a detection result of the sensor.

Claims

1. A sheet feeding device, comprising: a pick-up roller that draws out a plurality of sheets one by one from a sheet table on which the plurality of sheets are loaded; a sensor that detects presence or absence of the sheet; and a sheet feeding controller that controls drive to raise the pick-up roller on a basis of a detection result of the sensor.

2. The sheet feeding device according to claim 1, wherein the detection result includes a detection based on an impact applied to the sheet feeding device, and the sheet feeding controller controls the drive to raise the pick-up roller when the detection result is detected for a predetermined time or more.

3. The sheet feeding device according to claim 2, wherein the predetermined time is shorter than a time taken until the sensor determines that the sheet is present.

4. The sheet feeding device according to claim 1, wherein the sheet feeding controller controls the drive to raise the pick-up roller when a power supply of the sheet feeding device is turned on.

5. The sheet feeding device according to claim 1, further comprising an image reader that reads an image of the sheet, wherein the sheet feeding controller controls the drive to raise the pick-up roller after the image reader reads the image.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a view showing an outer appearance of an image forming apparatus.

[0012] FIG. 2 is a cross-sectional view showing a configuration of a document reader.

[0013] FIG. 3 is a block diagram showing a configuration of the image forming apparatus.

[0014] FIG. 4 is a state transition diagram of a sheet feeding roller (pick-up roller).

[0015] FIG. 5 is a diagram showing control related to a rotation direction of a DP motor.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0016] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0017] FIG. 1 is a view showing an outer appearance of an image forming apparatus 100.

[0018] The image forming apparatus 100 can selectively perform various modes such as copying, facsimile, scanner, and printer. For example, copying includes printing an image read from a document onto a recording sheet. In addition, for example, facsimile includes transmitting an image read from a document over a public network and printing the received image onto a recording sheet. Further, for example, scanner includes outputting an image read from a document to an external information terminal. In addition, for example, printer includes printing an image input from outside via a network or the like onto a recording sheet.

[0019] In FIG. 1, the image forming apparatus 100 includes a scanner unit 110, an image forming unit 113, and a sheet feeding unit 114.

[0020] The scanner unit 110 can read an image of a document. The scanner unit 110 includes a document reader 10 and an image reader 60. For example, the scanner unit 110 may be configured to be capable of reading an image of a document by using both a sheet-through method in which a document is moved to be read with a document reading element (scanner head) being kept stationary, and a scanner head method in which a document reading element is moved to read an image of a document from below the document placed on a platen glass.

[0021] The document reader (DP) 10 is an auto document feeder (ADF) and includes a document placing table 11 and a document discharge table 12. The document reader 10 reads a document placed on the document placing table 11 and discharges the document to the document discharge table 12. The specific structure of the document reader 10 will be described with reference to FIG. 2.

[0022] The image reader 60, above which the document reader 10 is provided, reads an image of the document placed on a platen glass 61 (see FIG. 2) to obtain image data.

[0023] For example, the image reader 60 may be provided with a first document reading element 62 (see FIG. 2) that reads a front surface of a document, and the document reader 10 may be provided with a second document reading element 19 (see FIG. 2) that reads a back surface of the document, thus reading both sides of the document by passing the document therethrough one time. Note that a contact image sensor (CIS) and the like may be used for the first document reading element 62 and the second document reading element 19.

[0024] The image forming unit 113 includes an image forming section 113A, a sheet feeding cassette 113B, a manual feeding tray 113C, a sheet discharge tray 113D, and a sorter 113E. In addition, the sheet feeding unit 114 includes a sheet feeding cassette 114A. The image forming unit 113 forms an image, in the image forming section 113A, on a recording sheet fed from the sheet feeding cassette 113B, the manual feeding tray 113C, or the sheet feeding cassette 114A and discharges the recording sheet to the sheet discharge tray 113D or the sorter 113E.

[0025] FIG. 2 is a cross-sectional view showing a configuration of the document reader 10.

[0026] The document reader 10 also includes a DP cover 14, a sheet feeding section 30, a first conveyance roller 16, a second conveyance roller 17, an actuator 18, the second document reading element 19, and a sheet discharge roller 20. In addition, the sheet feeding section 30, the first conveyance roller 16, the second conveyance roller 17, the actuator 18, the second document reading element 19, and the sheet discharge roller 20 are provided sequentially from the upstream side of a conveyance direction.

[0027] The DP cover 14 is disposed above the upper surface of a conveyance path 15 that conveys a document, the conveyance path 15 including the sheet feeding section 30, and covers them in an openable and closable manner. For example, the DP cover 14 is opened and closed by a user to resolve a paper jam or other problems. In this embodiment, no sensor is provided to detect the opened/closed state of the DP cover 14.

[0028] The sheet feeding section 30 includes a pick-up roller 31, a document presence/absence sensor 32, a stopper 33, and a sheet feeding roller 34. Note that the sheet feeding section 30 is illustrated with some parts such as a plurality of idle gears being omitted. Note that the configuration of the sheet feeding section 30 is not limited, and a mechanism for transmitting a driving force, such as a rotation shaft or a gear, may be configured discretionally.

[0029] The pick-up roller 31 is configured to be movable in the vertical direction by an actuator, a rod or a coil spring, and the like (not shown), and rotates to send the document placed on the document placing table 11 to the conveyance path 15. For example, the pick-up roller 31 is raised and lowered between a lower limit position where the pick-up roller 31 abuts on the upper surface of the document placing table 11 and an upper limit position where the pick-up roller 31 is away from the document placing table 11 by a predetermined distance (e.g., at a position where the sheet feeding section 30 abuts on the DP cover 14).

[0030] The document presence/absence sensor 32 detects the presence or absence of the document. In this embodiment, a detection signal detected by the document presence/absence sensor 32 is output to a sheet feeding controller 130 to be described later. For example, the document presence/absence sensor 32 is an PI sensor and detects the presence or absence of the document when a document passes through the conveyance path 15 and is detected by the actuator 18. Note that in this embodiment the document presence/absence sensor 32 and the actuator 18 function as sensors that detect the presence or absence of a sheet.

[0031] The stopper 33 permits or restricts the feeding of the document. For example, the stopper 33 pivots when the pick-up roller 31 pivots to take a sheet feeding posture, thus permitting the sending of a document. The stopper 33 fails to pivot when the pick-up roller 31 pivots to take a non-sheet feeding posture, and comes into contact with the tip position of a document bundle, thus restricting the sending of a document.

[0032] In the document bundle placed on the document placing table 11, the topmost document of the document bundle is sent from a sheet feeding port to the conveyance path 15 by the pick-up roller 31 and the sheet feeding roller 34, and the sent document is conveyed by the first conveyance roller 16 and the second conveyance roller 17. In addition, images of both sides of the sent document are read by the first document reading element 62 and the second document reading element 19 at a predetermined timing after the document is detected by the actuator 18. The document is then discharged from a discharge port by the sheet discharge roller 20 and stacked onto the document discharge table 12.

[0033] Here, it is necessary to raise the pick-up roller 31 when a document is set in the DP. Thus, when the power supply of the image forming apparatus 100 is turned on, it is necessary to perform the operation of raising the pick-up roller 31 after the DP performs reading or after the DP cover 14 (DP main body) is opened and closed.

[0034] However, this image forming apparatus is not equipped with a sensor that detects the opening and closing of the DP cover 14 for the purpose of a reduction of cost. Thus, in this embodiment, the image forming apparatus 100 includes the sheet feeding controller 130 that raises the pick-up roller 31 when it is detected that the document presence/absence sensor 32 is turned on for a certain time or more.

[0035] FIG. 3 is a block diagram showing a configuration of the image forming apparatus 100. Note that in FIG. 3 a block including the image forming unit 113 and the sheet feeding unit 114 will be described as a printer 120.

[0036] As shown in FIG. 3, the image forming apparatus 100 includes the printer 120 and the document reader 10. The printer 120 includes the image forming unit 113, the sheet feeding unit 114, an operation panel 115, and a controller 121. The operation panel 115 includes an operation section 116 that is capable of receiving an operation of a user, and a display section 117 that displays various settings and statuses of the image forming apparatus 100. For example, the operation section 116 includes a numeric keypad with which the number of prints can be input, an OK button that indicates an approval of the user, and the like. In addition, for example, the display section 117 may use an LE display. In addition to this, the operation panel may include a speaker or the like for informing the user of an abnormal state of the image forming apparatus 100, such as a paper jam (jam).

[0037] The controller 121 communicates with the document reader 10, controls an image reading operation of the image reader 60 according to the timing at which the document is conveyed, and controls the image forming unit 113 and the sheet feeding unit 114 on the basis of the image data acquired by the reading operation, to thereby perform image forming processing.

[0038] The document reader 10 includes the sheet feeding controller 130, a pick-up roller drive section 140, a conveyance roller drive section 141, a sheet discharge roller drive section 142, and the document presence/absence sensor 32.

[0039] The sheet feeding controller 130 includes a central processing unit (CPU) 131, a read only memory (ROM) 132, a random access memory (RAM) 133, and a nonvolatile memory 134. In this embodiment, the sheet feeding controller 130 performs processing of controlling the up-and-down movement (raising and lowering) of the pick-up roller 31.

[0040] The CPU 131 executes a control program stored in the ROM 132 to receive detection signals from the document presence/absence sensor 32 and various job execution instructions from the operation panel 115 by the user via the controller 121 of the printer 120, and controls the pick-up roller drive section 140, the conveyance roller drive section 141, and the sheet discharge roller drive section 142.

[0041] The ROM 132 stores a control program and the like for executing the operation of conveying documents. The RAM 133 is a nonvolatile memory and is a work area for the CPU 131 to perform programs. For example, an electrically erasable programmable read-only memory (EEPROM) is used for the nonvolatile memory 134, which is a data saving area for the CPU 131.

[0042] FIG. 4 is a state transition diagram of a sheet feeding roller (pick-up roller 31).

[0043] As shown in FIG. 4, the state of the sheet feeding roller is classified into five states of: initial state; in operation; operation completed; waiting for JAM processing; and operation restricted. "Initial state" indicates a state where the power supply of the image forming apparatus is turned on or a state restored from a sleep state. "In operation" indicates a state where the drive to raise the sheet feeding roller is started. "Operation completed" indicates a state where the drive to raise the sheet feeding roller is completed. "Waiting for JAM processing" indicates a state waiting for removal of a paper jam. "Operation restricted" indicates a state where the control to raise the pick-up roller 31 is restricted in a state of the conveyance for scanning.

[0044] In addition, in this embodiment, the cases are classified into three cases, and the control method for each case will be described with reference to FIG. 4.

Case 1

[0045] Case 1 is operation processing in which the sheet feeding roller is raised when the power supply of the image forming apparatus 100 is turned on.

[0046] As shown in FIG. 4, in Case 1, when the power supply is turned on or when the state is restored from a sleep state, the state of the sheet feeding roller is "initial state" (ST101). In this state, a permission for the drive to raise the sheet feeding roller (event: permission of operation) is output from the sheet feeding controller 130, and thus the state of the sheet feeding roller transitions to "in operation" (ST102). In ST102, the drive to raise the sheet feeding roller is started. When the drive to raise the sheet feeding roller is completed, the state transitions to "operation completed" (ST103). This makes it possible to set a document on the document placing table 11.

[0047] Note that a black circle 200 outside the frame indicates that the power supply of the image forming apparatus 100 is activated to proceed to the state transition of the sheet feeding roller. In addition, black circles 201, 202, and 203 in the frame indicate that their state information are notified.

Case 2

[0048] Case 2 is operation processing in which the sheet feeding roller is raised when the reading by the DP is completed.

[0049] FIG. 5 is a diagram showing the control related to a rotation direction of a DP motor. The DP motor can select raising of the pick-up roller 31 or conveying of a document for scanning, depending on the rotation direction. In this embodiment, in CW (Clockwise) of the DP motor, the pick-up roller 31 is raised, and in CCW (Counter Clockwise) of the DP motor, the document is sent to the conveyance path in order to perform scanning.

[0050] As shown in FIG. 5, the direction of the DP motor when the document is conveyed is the CCW. Further, since the same motor is used in the conveyance for scanning and the control of the pick-up roller 31, the pick-up roller 31 is lowered. In other words, when the reading by the DP is completed, it is necessary to raise the pick-up roller 31.

[0051] Referring back to FIG. 4, the control of raising the pick-up roller 31 in Case 2 will be described. First, in Case 2, the state of the pick-up roller 31 is "operation completed" (ST103). In addition, the state of "operation completed" is obtained at a timing at which an event notification output when the drive to raise the pick-up roller 31 is completed is supplied to the sheet feeding controller 130.

[0052] In addition, upon reception of a scanning request, the state of the pick-up roller 31 enters "operation restricted" (ST104). For example, a scanning request is supplied to the sheet feeding controller 130 when the user performs a scanning operation via the operation panel 115, and thus the state of the pick-up roller 31 enters "operation restricted". Note that RUN entry in FIG. 4 indicates that the state of the pick-up roller 31 transitions from "in operation" to "operation restricted". In addition, RUN exit indicates that the state of the pick-up roller 31 transitions from "operation restricted" to "in operation".

[0053] In addition, when scanning is completed, the following Case 2-1 and Case 2-2 occur. Case 2-1 is the state where there is no jam or no feeding of a first sheet (document is absent). In this case, the state of the pick-up roller 31 transitions from "operation restricted" (ST104) to "in operation" (ST102). When the drive to raise the pick-up roller 31 is completed, the state transitions to "operation completed" (ST103). This makes it possible to set a document on the document placing table 11.

[0054] Here, no feeding of a first sheet means the state where feeding of a first document is unsuccessful.

[0055] In addition, Case 2-2 is the state where there is a jam or no feeding of a first sheet (document is present). In this case, in order to raise the pick-up roller 31, the state of "operation restricted" (ST104) needs to transition to "waiting for JAM processing" (ST105).

[0056] In ST105, two cases are conceivable. First, if there is a jam, the jam is handled, and a command (FD55) requesting the release of the JAM is then supplied to the sheet feeding controller 130. Further, if there is no document in the DP, the state of the pick-up roller 31 transitions to "in operation" (ST102). In addition, when the state of the pick-up roller 31 transitions from ST102 to ST103, the drive to raise the pick-up roller 31 is completed. In such a manner, it is possible to set a document on the document placing table 11.

[0057] In the transition of the state where there is no jam (ST106) and the state where there is a jam (ST107), when a notification indicating that a jam occurs from the state where there is no jam is supplied to the sheet feeding controller 130, the state transitions from ST106 to ST107.

[0058] In addition, if there is no feeding of a first document or no document (ST108), the state of the pick-up roller 31 transitions to "in operation" (ST102). In addition, when the state of the pick-up roller 31 transitions from ST102 to ST103, the drive to raise the pick-up roller 31 is completed. In such a manner, it is possible to set a document on the document placing table 11.

[0059] In the transition between the state where a document is present (ST108) and the state where a document is absent (ST109), when a document is removed in the state of ST108, the state transitions to ST109, and when a document is set in the state of ST109, the state transitions to ST108.

Case 3

[0060] Case 3 is operation processing for the sheet feeding roller, in which the pick-up roller 31 is raised using the operation panel when the DP cover 14 is opened and closed or the DP main body is opened and closed.

[0061] Here, one of the causes for no sheet feeding is that a document bundle with a near-full loading capacity is set after the DP is opened and closed or after the document bundle is aligned on the upper surface (top surface) of the DP. This is because the impact applied to the DP exceeds a torque limiter setting value at which the pick-up roller 31 is held, causing the position of the roller to be lowered and releasing the stopper 33 that stops the documents. When the document bundle with the near-full loading capacity is inserted to the back with the stopper 33 being released, the documents go beyond the stopper 33 and are jammed between a front separation PAD and an upper cover rib (see a dashed rectangle 50 of FIG. 2), resulting in no sheet feeding.

[0062] For example, in the model of a type that is not equipped with a sensor to detect the opening and closing of the DP cover 14 or the DP main body, like the image forming apparatus 100, the user controls the raising of the pick-up roller 31 via the operation panel 115. Such operation using the operation panel 115 is time-consuming. In addition, if a document is inserted without operating the operation panel 115, the document comes into contact with the pick-up roller 31, and the tip of the document will be damaged.

[0063] In this regard, in this embodiment, the fact that the document presence/absence sensor 32 is turned on and off in a short time is used for shock detection based on a shock applied to the DP. The control is changed as follows: after the time in which the document presence/absence sensor 32 detects the presence or absence of a document is shortened, the pick-up roller 31 is raised when a document is detected, and the stopper 33 is returned.

[0064] Here, the document presence/absence sensor 32 bounces due to vibrations when the DP cover 14 is opened and closed or when the DP main body is opened and closed. For example, when the DP cover 14 (or DP main body) is closed, it takes about 20 ms for the document presence/absence sensor 32 to fall due to gravity. Therefore, in this embodiment, if the document presence/absence sensor 32 outputs a detection time of 6 ms or longer in consideration of the likelihood, it is determined that the DP cover 14 (or DP main body) is closed. In other words, if the detection time from the document presence/absence sensor 32 is output for 6 ms or longer, which is shorter than the time taken until the document presence/absence sensor 32 determines that a document is present, the sheet feeding controller 130 performs the drive to raise the pick-up roller 31.

[0065] In Case 3, if the DP is opened and closed or the document bundle is aligned on the upper surface (top surface) of the DP after "operation completed" (ST103), and the document presence/absence sensor 32 is then turned on, a detection signal (event: document (document present)) is supplied to the sheet feeding controller 130. Thus, the state of the pick-up roller 31 transitions to "in operation" (ST102).

[0066] Here, two cases (Case 3-1 and Case 3-2) occur when the drive to raise the pick-up roller 31 is started. In Case 3-1, the raising of the pick-up roller 31 is completed because the document has been detected. In other words, this is the state where feeding can be performed without problem. In addition, Case 3-2 is a state where the presence or absence of a document has been detected in a short time.

[0067] In Case 3-1, if there is no action that affects the signal output from the document presence/absence sensor 32 while the pick-up roller 31 is in operation (during the drive to raise the pick-up roller 31), the raising of the pick-up roller 31 is completed, and the state of the pick-up roller 31 transitions to "operation completed" (ST103). In this case, a document can be set by raising the pick-up roller 31 without requiring the operation of the operation panel 115.

[0068] In Case 3-2, if there is action that affects the signal output from the document presence/absence sensor 32 while the pick-up roller 31 is in operation, the state of the pick-up roller 31 is "in operation" (ST102). Even if the state of the document presence/absence sensor 32 (on or off) is changed, it is necessary to wait until the drive to raise the pick-up roller 31 is completed before continuing the processing. For example, the action that affects the signal output from the document presence/absence sensor 32 includes a case where an on/off determination using the sensor signal (document detection) is performed in a short time due to vibrations caused by, for example, aligning the documents on the DP during the operation of the pick-up roller 31. In such a case, the state transition is determined after waiting until the operation of the pick-up roller 31 is completed (waiting until the operation of the pick-up roller 31 is completed in consideration of the variations of the document detection).

[0069] In such a manner, use of the signal of the document presence/absence sensor 32 makes it possible to change the state of the pick-up roller 31 without the panel operation and to raise the pick-up roller 31.

[0070] As described above, the document reader 10 according to this embodiment includes the pick-up roller 31 that draws out a plurality of documents one by one from the document placing table 11 on which the plurality of documents are loaded, the document presence/absence sensor 32 that detects the presence or absence of a document, and the sheet feeding controller 130 that controls the drive to raise the pick-up roller 31 on the basis of a detection result of the document presence/absence sensor 32. This makes it possible to reduce a complicated operation using the operation panel or the like and to raise the pick-up roller without attaching a sensor that detects the opening and closing of the cover.

[0071] Conventionally, in sheet feeding devices equipped with no sensors that detect the opening and closing of the DP for the purpose of a reduction of cost, the pick-up roller has been raised by a complicated operation using an operation panel to raise the pick-up roller. In addition, if a document is inserted without the operation, the document comes into contact with the DP sheet-feeding pick-up roller and the tip of the document is damaged.

[0072] In the present technology, the opening and closing of the DP is determined by the on/off behavior of the document presence/absence sensor when the DP is opened and closed. In particular, when the DP is closed, the likelihood of the time taken for the document presence/absence sensor to fall due to gravity is considered to shorten the time during which the presence of a document is detected. When the document presence/absence sensor detects that there is a document for a predetermined time or more, it is determined that the DP is closed, and the pick-up roller is raised. This makes it possible to reduce a complicated operation using the operation panel or the like and to raise the pick-up roller without attaching a sensor that detects the opening and closing of the cover.

[0073] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.