Sheet feeding device, image forming device

Abstract

To detect a sheet residual amount at a plurality of stages without increasing the number of sensors.SOLUTION: Each of a plurality of main movable members 51 includes a contact wall part 511 and a main contact part 512. Each of a plurality of sub movable members 52 includes a sub contact part 521 and one or a plurality of parts 522 to be detected. When a state where an object sheet of each of a plurality of layer regions exists is changed into a state where it does not exist, under the condition that a sheet container 12 is mounted on a body part 11, each of the plurality of sub movable members 52 corresponding to each of the plurality of layer regions whose state has changed moves to a second reference position from a second retreat position. When each of the plurality of sub movable members 52 moves from one of the second reference position and the second retreat position to the other, one or the plurality of parts 522 to be detected of each of the plurality of sub movable members 52 passes a detection region. A determination part 8c determines a sheet loading amount by counting the number of rise changes or the number of fall changes of a detection signal.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device and an image forming apparatus capable of detecting the amount of sheets stacked in a sheet container. [Background technology]

[0002] In an image forming apparatus, a sheet feeding device feeds a plurality of sheets in a sheet cassette one by one to a transport path, and a printing device forms an image on the sheet transported along the transport path.

[0003] The image forming apparatus may include a remaining sheet amount detection mechanism that detects the amount of sheets remaining in the sheet cassette.

[0004] For example, it is known that the remaining amount detection mechanism includes an actuator that swings in response to the amount of stacked sheets and a photosensor (see, for example, Patent Document 1).

[0005] The photosensor detects that the actuator has been swung to a specific position, for example, the position of the actuator when the sheet stack amount is zero. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP2005-82343 Public Relations Summary of the Invention [Problem to be solved by the invention]

[0007] Meanwhile, there is a need to detect the remaining amount of sheets in a plurality of stages in the sheet feeding device, and there is also a need to detect the remaining amount of sheets in a plurality of stages without increasing the number of sensors such as the photosensors.

[0008] An object of the present invention is to provide a sheet feeding device and an image forming apparatus capable of detecting the remaining amount of sheets at a plurality of levels without increasing the number of sensors. [Means for solving the problem]

[0009] A sheet feeding device according to one aspect of the present invention includes a sheet container, a sending mechanism, a plurality of main movable members, a plurality of auxiliary movable members, a biasing unit, an object detection unit, and a determination unit. The sheet container is attached to the main body unit so as to be able to be pulled out along a reference direction, and is capable of stacking a plurality of sheets. The sending mechanism sends out the plurality of sheets one by one from the sheet container. The plurality of main movable members are supported by the sheet container so as to be able to move between a first reference position and a first retracted position along the reference direction. The plurality of auxiliary movable members are supported by the main body unit so as to be able to move between a second reference position and a second retracted position, and come into contact with the plurality of main movable members by attaching the sheet container to the main body unit. The biasing unit biases the plurality of auxiliary movable members toward the second reference position. The object detection unit is supported by the main body unit, detects an object present in a detection area in the main body unit, and outputs a detection signal. The determination unit determines the amount of sheets stacked in the sheet container based on a change in the detection signal. Each of the main movable members has an abutment wall and a main abutment. The abutment wall is disposed in each of a plurality of layer regions having different heights in the sheet container, and abuts against one end of the target sheet when the plurality of sheets includes one or more target sheets located at a corresponding height among the plurality of layer regions. The main abutment is disposed outside the sheet container, and abuts against each of the plurality of secondary movable members when the sheet container is attached to the main body. Each of the plurality of secondary movable members has a secondary abutment and one or more detection parts. The secondary abutment abuts against the main abutment of each of the plurality of main movable members. The one or more detection parts pass through the detection area in response to the movement of each of the plurality of secondary movable members. The plurality of secondary movable members each have a different number of the detection parts. When the target sheet is not present, each of the plurality of main movable members is held at the first reference position by a force received from the biasing part via each of the plurality of secondary movable members. When the target sheet is present, each of the main movable members is held at the first retracted position by a force received by the contact wall portion from the target sheet.When the sheet container is attached to the main body, each of the plurality of secondary movable members moves from the second reference position to the second retracted position due to the force of the secondary contact portion received from the primary contact portion when each of the corresponding plurality of primary movable members is in the first retracted position. When the target sheet in each of the plurality of layer regions changes from a state in which the target sheet is present to a state in which the target sheet is not present under the condition in which the sheet container is attached to the main body, each of the plurality of secondary movable members corresponding to each of the plurality of layer regions whose state has changed moves from the second retracted position to the second reference position due to the force of the biasing portion. When each of the plurality of secondary movable members moves from one of the second reference position and the second retracted position to the other, one or more of the detected portions of each of the plurality of secondary movable members pass through the detection area. The determination portion determines the sheet load amount by counting the number of rising or falling changes of the detection signal.

[0010] An image forming apparatus according to another aspect of the present invention includes the sheet feeding device described above, and a printing device that forms an image on a sheet fed from the sheet feeding device. Effect of the Invention

[0011] According to the present invention, it is possible to provide a sheet feeding device and an image forming apparatus capable of detecting the remaining amount of sheets at a plurality of levels without increasing the number of sensors. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing the configuration of a control device in the image forming apparatus according to the embodiment. [Diagram 3] FIG. 3 is a perspective view of a sheet amount detection unit in the image forming apparatus according to the embodiment. [Figure 4] FIG. 4 is a plan view of the sheet amount detection unit in the first state in the image forming apparatus according to the embodiment. [Diagram 5]FIG. 5 is a plan view of the sheet amount detection unit in the second state in the image forming apparatus according to the embodiment. [Figure 6] FIG. 6 is a plan view of the sheet amount detection unit in the third state in the image forming apparatus according to the embodiment. [Figure 7] FIG. 7 is a plan view of the sheet amount detection unit in the fourth state in the image forming apparatus according to the embodiment. [Figure 8] FIG. 8 is a plan view of the sheet amount detection unit in the fifth state in the image forming apparatus according to the embodiment. [Figure 9] FIG. 9 is a diagram showing an example of a time chart of a detection signal of a photosensor in the image forming apparatus according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0014] [Configuration of image forming apparatus 10] An image forming apparatus 10 according to the embodiment includes a sheet feeding device 1 and a printing device 2. The printing device 2 includes a sheet conveying device 3 and an image forming section 4.

[0015] The sheet feeding device 1 stores a plurality of sheets 9, and feeds the plurality of sheets 9 one by one to a conveying path 30 in the printing device 2.

[0016] The sheet feeding device 1 includes a lower main body portion 11, a sheet cassette 12, and a delivery mechanism 14 (see FIG. 1). The lower main body portion 11 is a housing disposed below the printing device 2.

[0017] The sheet cassette 12 is attached to the lower main body portion 11 so as to be removable in a reference direction D1. The sheet cassette 12 is capable of holding a plurality of sheets 9 therein.

[0018] The sheet cassette 12 has a sheet tray 13 therein, and a plurality of sheets 9 are stacked on the sheet tray 13. The sheet cassette 12 is an example of a sheet container. For example, the reference direction D1 is a direction along a horizontal plane.

[0019] 1 and 3 to 8, an installation direction D11 is a direction in which the sheet cassette 12 moves when the sheet cassette 12 is installed in the lower main body portion 11. A withdrawal direction D12 is a direction in which the sheet cassette 12 moves when the sheet cassette 12 is withdrawn from the lower main body portion 11.

[0020] 1 and 3 to 8, the intersecting direction D2 is a direction intersecting the reference direction D1. In this embodiment, the intersecting direction D2 is a direction perpendicular to the reference direction D1 in a horizontal plane.

[0021] The delivery mechanism 14 delivers the sheets 9 in the sheet cassette 12 one by one from the sheet cassette 12 to a conveyance path 30 of the printing device 2 .

[0022] The sheet feeding device 1 further includes a mounting sensor 15 (see FIG. 1). The mounting sensor 15 detects a mounting state in which the sheet cassette 12 is mounted in the lower main body portion 11.

[0023] For example, the installation sensor 15 is a contact sensor or a non-contact sensor that detects the sheet cassette 12 when the sheet cassette 12 is present at the installation position in the lower main body portion 11. The contact sensor is, for example, a microswitch. The non-contact sensor is, for example, a reflective photosensor.

[0024] The printing device 2 forms an image on a sheet 9 sent out from the sheet feeding device 1. In the printing device 2, a sheet transport device 3 transports the sheet 9 along a transport path 30. The sheet transport device 3 includes a plurality of transport roller pairs 31 that transport the sheet 9 by rotating.

[0025] The image forming section 4 forms an image on the sheet 9 conveyed along the conveying path 30. The sheet conveying device 3 discharges the sheet 9 on which the image has been formed from the conveying path 30 to a discharge tray 21.

[0026] 1, the image forming unit 4 forms an image on a sheet 9 by an electrophotographic method. In this case, the image forming unit 4 includes an exposure device 40, a photoconductor 41, a charging device 42, a developing device 43, a transfer device 44, a cleaning device 45, and a fixing device 46.

[0027] The charging device 42 charges the surface of the rotating photoconductor 41 , and the exposure device 40 writes an electrostatic latent image onto the charged surface of the photoconductor 41 .

[0028] A developing device 43 develops the electrostatic latent image into a toner image, and a transfer device 44 transfers the toner image from the photoreceptor 41 to a sheet 9. A cleaning device 45 removes waste toner from the surface of the photoreceptor 41.

[0029] The fixing device 46 applies heat and pressure to the toner image on the sheet 9 to fix the toner image to the sheet 9 .

[0030] The image forming apparatus 10 further includes an operation device 801 , a display device 802 , and a control device 8 .

[0031] The operation device 801 is a device that accepts operations by a person. For example, the operation device 801 includes one or both of a touch panel and operation buttons.

[0032] The display device 802 is capable of displaying various types of information. For example, the display device 802 is a panel display device such as a liquid crystal display device. The control device 8 controls various types of electric devices included in the image forming apparatus .

[0033] As shown in FIG. 2, the control device 8 includes a central processing unit (CPU) 80, a random access memory (RAM) 81, a secondary storage device 82, a signal interface 84, a communication device 83, and the like.

[0034] The CPU 80 executes various control and data processing operations by executing computer programs. The RAM 81 temporarily stores the computer programs executed by the CPU 80 and various data.

[0035] The secondary storage device 82 is a computer-readable non-volatile storage device. The secondary storage device 82 stores the computer programs executed by the CPU 80 and various data. For example, one or both of a flash memory and a hard disk drive are adopted as the secondary storage device 82.

[0036] The signal interface 84 converts the detection signals of the various sensors into digital detection data. The detection data is transmitted to the CPU 80.

[0037] The communication device 83 communicates with a plurality of external devices including one or more host devices through a network. The CPU 80 communicates with each of the external devices through the communication device 83. The host device is an information processing device that requests the image forming apparatus 10 to perform the print process.

[0038] The CPU 80 includes a plurality of processing modules that are realized by executing the computer programs, including a main control unit 8a, a print control unit 8b, and a determination unit 8c (see FIG. 2).

[0039] The main control unit 8a executes a process of receiving various requests and a control of making other modules execute processes according to the requests. For example, the main control unit 8a receives a print request through the operation device 801 or the communication device 83. Furthermore, the main control unit 8a causes the print control unit 8b to execute a process according to the print request.

[0040] The print control unit 8b controls the sheet feeding device 1, the sheet conveying device 3, and the image forming unit 4. The print control unit 8b causes the sheet conveying device 3 to execute a process of conveying a sheet 9, and causes the image forming unit 4 to execute a process of forming an image on the sheet 9.

[0041] The determination unit 8c determines various states of the image forming apparatus 10 according to the detection states of various sensors in the image forming apparatus 10 and the operating states of various devices.

[0042] Incidentally, there is a need to detect the remaining amount of sheets at multiple stages in the sheet feeding device 1. On the other hand, there is also a need to detect the remaining amount of sheets at multiple stages without increasing the number of sensors.

[0043] [Configuration of sheet amount detection unit 5] The sheet feeding device 1 further includes a sheet amount detection unit 5 (see FIGS. 1 and 3).

[0044] The sheet amount detection unit 5 includes a plurality of main movable members 51, a plurality of sub movable members 52, a biasing unit 53, and a photosensor 54 (see FIGS. 1 and 3).

[0045] The main movable members 51 are each supported so as to be movable along the reference direction D1 by the sheet cassette 12. The main movable members 51 are each supported so as to be movable between a first reference position and a first retracted position.

[0046] The first reference position and the first retracted position are positions based on the sheet cassette 12. The first reference position is an end position in the pull-out direction D12 side of the movable range of each of the main movable members 51. The first retracted position is an end position in the installation direction D11 side of the movable range of each of the main movable members 51.

[0047] Fig. 7 shows a state in which all of the main movable members 51 are located at the first reference position. Figs. 3, 4 and 8 show a state in which all of the main movable members 51 are located at the first retracted position.

[0048] The plurality of secondary movable members 52 are each movably supported by the lower main body portion 11. When the sheet cassette 12 is attached to the lower main body portion 11, the plurality of secondary movable members 52 come into contact with the plurality of main movable members 51, respectively.

[0049] In this embodiment, the multiple auxiliary movable members 52 are each supported so as to be movable between a second reference position and a second retracted position along the reference direction D1.

[0050] The second reference position and the second retracted position are positions based on the lower main body portion 11. The second reference position is an end position of the movable range of each of the plurality of sub movable members 52 in the pull-out direction D12 side. The second retracted position is an end position of the movable range of each of the plurality of sub movable members 52 in the mounting direction D11 side.

[0051] 7 and 8 show a state in which all of the sub movable members 52 are located at the second reference position, while Figures 3 and 4 show a state in which all of the sub movable members 52 are located at the second retracted position.

[0052] The biasing portion 53 biases each of the plurality of secondary movable members 52 toward the second reference position individually. In this embodiment, the biasing portion 53 is a plurality of springs connected to each of the plurality of secondary movable members 52 and the lower main body portion 11.

[0053] The photosensor 54 is supported by the lower main body portion 11. The photosensor 54 is a sensor that detects an object present within a detection area 540 in the lower main body portion 11. In this embodiment, the photosensor 54 is a transmission type photosensor.

[0054] The photosensor 54 has a light emitting section 541 and a light detecting section 542. The light emitting section 541 emits detection light along the intersecting direction D2 to the detection region 540. The light detecting section 542 is a photoelectric conversion element that detects the detection light passing through the detection region 540.

[0055] The photosensor 54 is an example of a non-contact type object detection unit that detects an object present in the detection area 540. The photosensor 54 may be a reflective photosensor. In this case, the light detection unit 542 detects reflected light of the detection light.

[0056] The light detection portion 542 of the photosensor 54 outputs a detection signal DS1 (see FIG. 9). The determination portion 8c determines the amount of sheets stacked in the sheet cassette 12 based on a change in the detection signal DS1.

[0057] The determining unit 8c determines the state of the stacked amount of sheets in a plurality of stages based on a change in the detection signal DS1. The determining unit 8c, which determines the stacked amount of sheets, constitutes a part of the sheet feeding device 1.

[0058] Each of the multiple main movable members 51 has a contact wall portion 511, a main contact portion 512, and a first connecting portion 513. The first connecting portion 513 is a portion that connects the contact wall portion 511 and the main contact portion 512 together.

[0059] Each of the multiple sub movable members 52 has a sub abutment portion 521, one or more detected portions 522, and a second connection portion 523. The second connection portion 523 is a portion that connects the sub abutment portion 521 and the one or more detected portions 522.

[0060] The contact walls 511 of the main movable members 51 are disposed in the respective layer regions L1 to L4 having different heights in the sheet cassette 12 (see FIG. 3).

[0061] In this embodiment, the sheet feeding device 1 includes four main movable members 51 and four sub-movable members 52 corresponding to the four layer regions L1 to L4 (see FIG. 3).

[0062] The four layer regions L1 to L4 include a first layer region L1 which is the lowest, a second layer region L2 which is the second from the bottom, a third layer region L3 which is the third from the bottom, and a fourth layer region L4 which is the top (see FIG. 3).

[0063] The four main movable members 51 include a first main movable member 51a corresponding to the first layer region L1, a second main movable member 51b corresponding to the second layer region L2, a third main movable member 51c corresponding to the third layer region L3, and a fourth main movable member 51d corresponding to the fourth layer region L4 (see FIG. 3).

[0064] The four sub-movable members 52 include a first sub-movable member 52a that abuts the first main movable member 51a, a second sub-movable member 52b that abuts the second main movable member 51b, a third sub-movable member 52c that abuts the third main movable member 51c, and a fourth sub-movable member 52d that abuts the fourth main movable member 51d (see Figure 3).

[0065] That is, the first sub movable member 52a, the second sub movable member 52b, the third sub movable member 52c and the fourth sub movable member 52d correspond to the first layer region L1, the second layer region L2, the third layer region L3 and the fourth layer region L4, respectively.

[0066] The abutment wall portion 511 of each main movable member 51 abuts against one end of the target sheet 9x when the multiple sheets 9 in the sheet cassette 12 include one or more target sheets 9x located at a corresponding height among the four layer areas L1 to L4 (see Figure 3).

[0067] FIG. 3 shows a state in which a plurality of sheets 9 are stacked in the sheet cassette 12 up to a fourth layer area L4.

[0068] The main contact portion 512 of each of the main movable members 51 is disposed outside the sheet cassette 12 (see FIGS. 4 to 8). When the sheet cassette 12 is attached to the lower main body portion 11, each of the main movable members 51 comes into contact with a sub-contact portion 521 of each of the sub-movable members 52 (see FIGS. 3 to 7).

[0069] 8 shows a state in which the sheet cassette 12 is pulled out from the lower main body portion 11. As the sheet cassette 12 is pulled out from the lower main body portion 11, the sub-contact portions 521 of the sub movable members 52 move away from the main contact portions 512 of the main movable members 51 (see FIG. 8).

[0070] When the sheet cassette 12 is attached to the lower main body portion 11 , the sub-contact portions 521 of the sub-movable members 52 come into contact with the main contact portions 512 of the main movable members 51 .

[0071] The one or more detected parts 522 in each of the sub movable members 52 are parts that pass through the detection region 540 in response to the movement of each of the sub movable members 52. The four sub movable members 52 each have a different number of detected parts 522 (see FIGS. 3 to 8).

[0072] In this embodiment, the first sub movable member 52a has one detected portion 522. The second sub movable member 52b has two detected portions 522 arranged at intervals in the reference direction D1. The third sub movable member 52c has three detected portions 522 arranged at intervals in the reference direction D1. The fourth sub movable member 52d has four detected portions 522 arranged at intervals in the reference direction D1.

[0073] When the corresponding target sheet 9x is not present, each of the four main movable members 51 is held at the first reference position by a force received from the biasing portion 53 via each of the four sub movable members 52 (see FIGS. 5 to 7).

[0074] On the other hand, when the corresponding target sheet 9x is present, each of the four main movable members 51 is held in the first retracted position by the force that the contact wall portion 511 receives from the target sheet 9x (see FIGS. 5 to 7).

[0075] 3 and 4 show the sheet amount detection unit 5 when a plurality of sheets 9 in the sheet cassette 12 are stacked up to the fourth layer area L4.

[0076] 3 and 4, there is a target sheet 9x from the first layer region L1 to the fourth layer region L4. In this case, all of the four main movable members 51 are held in the first retracted position by the forces received from the target sheets 9x from the first layer region L1 to the fourth layer region L4.

[0077] 3 and 4, all of the four secondary movable members 52 are held in the second retracted position by the forces received from the four main movable members 51, respectively.

[0078] 3 and 4, the four secondary movable members 52 are held in the first retracted position against the force of the biasing portion 53. In FIG.

[0079] FIG. 5 shows the sheet amount detection unit 5 when a plurality of sheets 9 in the sheet cassette 12 are stacked up to the third layer area L3.

[0080] 5, there is no target sheet 9x in the fourth layer region L4. In this case, the fourth main movable member 51d is held at the first reference position by the force received from the biasing portion 53 via the fourth sub movable member 52d.

[0081] In FIG. 5, the fourth sub movable member 52d is held in the second reference position by the force applied from the biasing portion 53. As shown in FIG.

[0082] 5, a target sheet 9x exists from the first layer region L1 to the third layer region L3. In this case, the first main movable member 51a, the second main movable member 51b, and the third main movable member 51c are held in the first retracted position by forces received from the target sheet 9x from the first layer region L1 to the third layer region L3.

[0083] In FIG. 5, the first sub movable member 52a, the second sub movable member 52b and the third sub movable member 52c are held in the second retracted position by forces received from the first main movable member 51a, the second main movable member 51b and the third main movable member 51c, respectively.

[0084] In FIG. 5, the first main movable member 51a, the second main movable member 51b and the third main movable member 51c are held against the force of the biasing portion 53 in the first retracted position.

[0085] FIG. 6 shows the sheet amount detection unit 5 when a plurality of sheets 9 in the sheet cassette 12 are stacked up to the second layer area L2.

[0086] 6, there is no target sheet 9x in the third layer region L3 and the fourth layer region L4. In this case, the third main movable member 51c and the fourth main movable member 51d are held at the first reference position by the force received from the biasing portion 53 via the third sub movable member 52c and the fourth sub movable member 52d.

[0087] 6, there is a target sheet 9x in the first layer region L1 and the second layer region L2. In this case, the first main movable member 51a and the second main movable member 51b are held in the first retracted position by the forces received from the target sheet 9x in the first layer region L1 and the second layer region L2.

[0088] In FIG. 6, the first sub movable member 52a and the second sub movable member 52b are held in the second retracted position by forces received from the first main movable member 51a and the second main movable member 51b, respectively.

[0089] In FIG. 6, the first main movable member 51a and the second main movable member 51b are held against the force of the biasing portion 53 in the first retracted position.

[0090] FIG. 7 shows the sheet amount detection unit 5 when the sheet cassette 12 is in an empty state where no sheets 9 are present therein.

[0091] In FIG. 7, all of the four main movable members 51 are held in the first reference position by the force received from the biasing portion 53 via the four sub movable members 52.

[0092] In FIG. 7, all of the four secondary movable members 52 are held in the second reference position by the force applied from the biasing portion 53.

[0093] As shown in FIG. 8, even when the sheet cassette 12 is pulled out from the mounting position, all of the four auxiliary movable members 52 are held in the second reference position.

[0094] Although not shown, when multiple sheets 9 in the sheet cassette 12 are stacked up to the first layer area L1, the first main movable member 51a is held in the first retracted position, and the second main movable member 51b, the third main movable member 51c and the fourth main movable member 51d are held in the first reference position.

[0095] Similarly, when multiple sheets 9 in the sheet cassette 12 are stacked up to the first layer area L1, the first sub-movable member 52a is held in the second retracted position, and the second sub-movable member 52b, the third sub-movable member 52c and the fourth sub-movable member 52d are held in the second reference position.

[0096] As shown in FIGS. 5 to 8, in one or more of the four sub movable members 52 that are in the second reference position, the detected portion 522 is located on the pull-out direction D12 side with respect to the detection region 540.

[0097] On the other hand, as shown in FIGS. 3 to 6, in one or more of the four secondary movable members 52 that are in the second retracted position, the detected portion 522 is located on the mounting direction D11 side with respect to the detection area 540.

[0098] Each of the main movable members 51 moves from one of the first reference position and the first retracted position to the other depending on the presence or absence of the corresponding target sheet 9x.

[0099] Specifically, each of the main movable members 51 moves from the first reference position to the first retracted position when the corresponding target sheet 9x changes from a non-existent state to a present state. This state change usually occurs when the sheet cassette 12 is pulled out from the lower main body portion 11.

[0100] On the other hand, when the state where the corresponding target sheet 9x is present changes to the state where it is not present, each of the main movable members 51 moves from the first retracted position to the first reference position by the action of the biasing portion 53. This state change occurs regardless of whether the sheet cassette 12 is attached to the lower main body portion 11 or not.

[0101] When the sheet cassette 12 is attached to the lower main body portion 11, each of the secondary movable members 52 moves from the second reference position to the second retracted position due to the force that the secondary abutment portion 521 receives from the primary abutment portion 512 when each of the corresponding primary movable members 51 is in the first retracted position.

[0102] When the target sheet 9x in each of the four layer regions L1 to L4 changes from a state in which it is present to a state in which it is not present while the sheet cassette 12 is attached to the lower main body portion 11, the sub movable members 52 corresponding to the four layer regions L1 to L4 whose states have changed move. At that time, the sub movable members 52 corresponding to the four layer regions L1 to L4 whose states have changed move from the second retracted position to the second reference position by the force of the biasing portion 53.

[0103] When each of the secondary movable members 52 moves from one of the second reference position and the second retracted position to the other, one or more of the detected portions 522 of each of the secondary movable members 52 pass through the detection region 540 .

[0104] Specifically, when each of the secondary movable members 52 moves from the second reference position to the second retracted position, one or more of the detected portions 522 of each of the secondary movable members 52 pass through the detection area 540 in the mounting direction D11.

[0105] On the other hand, when each of the secondary movable members 52 moves from the second retracted position to the second reference position, one or more of the detected portions 522 of each of the secondary movable members 52 pass through the detection area 540 in the pull-out direction D12.

[0106] In this embodiment, when all four secondary movable members 52 are positioned at the second reference position or the second retracted position, the ten detectable portions 522 of the four secondary movable members 52 are arranged so that the number of overlapping portions 522 varies at multiple positions in the reference direction D1 when viewed from the intersecting direction D2.

[0107] As shown in FIGS. 3 and 4, the ten detection targets 522 are formed at four different positions P1 to P4 in the reference direction D1.

[0108] 4, one detection target portion 522 of each of the four sub movable members 52 is formed at a first position P1 in the reference direction D1. As a result, at the first position P1, the four detection target portions 522 are arranged so as to overlap each other when viewed from the intersecting direction D2.

[0109] Further, one detected portion 522 of each of the second sub movable member 52b, the third sub movable member 52c, and the fourth sub movable member 52d is formed at a second position P2 in the reference direction D1 (see FIG. 4). As a result, at the second position P2, the three detected portions 522 are arranged so as to overlap each other when viewed from the intersecting direction D2.

[0110] Further, one detected portion 522 of each of the third sub movable member 52c and the fourth sub movable member 52d is formed at a third position P3 in the reference direction D1 (see FIG. 4). As a result, at the third position P3, the two detected portions 522 are arranged so as to overlap each other when viewed from the intersecting direction D2.

[0111] Moreover, one detected portion 522 of the fourth sub movable member 52d is formed at a fourth position P4 in the reference direction D1 (see FIG. 4). As a result, only one detected portion 522 is disposed at the fourth position P4.

[0112] When the secondary movable member 52 moves, the multiple detected parts 522 arranged to overlap each other when viewed from the intersecting direction D2 pass through the detection area 540 at the same time.

[0113] When one or more detected portions 522 of each of the secondary movable members 52 pass through the detection region 540, the detection signal DS1 of the photosensor 54 changes (see FIG. 9).

[0114] FIG. 9 shows an example of the change in the detection signal DS1 when the four detected parts 522 pass through the detection area 540. As shown in FIG.

[0115] 9, the photosensor 54 outputs an active-high detection signal DS1. In this case, the photosensor 54 outputs a high-level detection signal DS1 when it detects the detection target portion 522. Note that the detection signal DS1 may be an active-low signal.

[0116] The determination unit 8c of the CPU 80 constantly monitors the detection signal DS1. For example, the determination unit 8c checks for a change in the level of the detection signal DS1 at predetermined intervals.

[0117] The determination unit 8c counts the number of rising transitions or falling transitions of the detection signal DS1. For example, the determination unit 8c counts the transitions of the detection signal DS1 within a predetermined time after the transition of the detection signal DS1 occurs. The determination unit 8c determines the sheet stack amount based on the count value of the transitions of the detection signal DS1.

[0118] In this embodiment, when the first sub movable member 52a moves, the count value is 1. When the second sub movable member 52b moves, the count value is 2. When the third sub movable member 52c moves, the count value is 3. When the fourth sub movable member 52d moves, the count value is 4.

[0119] In the present embodiment, the determining unit 8c determines which of five remaining amount states the sheet stack amount is in. The five remaining amount states include an empty state, a first remaining amount state, a second remaining amount state, a third remaining amount state, and a fourth remaining amount state.

[0120] The empty state is a state in which no sheets 9 are present in the sheet cassette 12. The first remaining state is a state in which the sheets 9 are stacked up to a first layer area L1. The second remaining state is a state in which the sheets 9 are stacked up to a second layer area L2.

[0121] The third remaining state is a state in which the sheets 9 are stacked up to a third layer region L3, and the fourth remaining state is a state in which the sheets 9 are stacked up to a fourth layer region L4.

[0122] For example, when the four layer regions L1 to L4 are uniform regions, the first remaining amount state corresponds to a remaining amount of 1 to 25%, the second remaining amount state corresponds to a remaining amount of 26 to 50%, the third remaining amount state corresponds to a remaining amount of 51 to 75%, and the fourth remaining amount state corresponds to a remaining amount of 76 to 100%.

[0123] The determining section 8c determines the sheet stack amount according to the detection result of the mounting sensor 15 and the count value.

[0124] In the following description, when the mounting state changes from an undetected state to a detected state, the count value counted immediately before the mounting state is detected is referred to as the mounting count value.

[0125] Similarly, when the attachment state changes from a detected state to an undetected state, the most recently counted value after the attachment state is no longer detected is referred to as the withdrawal count value.

[0126] Similarly, the count value counted while the wearing state is detected is referred to as a normal count value.

[0127] The determining unit 8c determines that the sheet stack amount is in the empty state when the installation count value is 0. Furthermore, the determining unit 8c determines that the sheet stack amount is in the first remaining amount state when the installation count value is 1.

[0128] Furthermore, the determination unit 8c determines that the sheet stack amount is in the second remaining amount state when the installation count value is 2. Furthermore, the determination unit 8c determines that the sheet stack amount is in the third remaining amount state when the installation count value is 3. Furthermore, the determination unit 8c determines that the sheet stack amount is in the fourth remaining amount state when the installation count value is 4.

[0129] The determining unit 8c determines that the sheet stack amount is in the third remaining amount state when the normal count value is 4. Furthermore, the determining unit 8c determines that the sheet stack amount is in the second remaining amount state when the normal count value is 3.

[0130] Furthermore, the determination unit 8c determines that the sheet stack amount is in the first remaining amount state when the normal count value is 2. Furthermore, the determination unit 8c determines that the sheet stack amount is in the empty state when the normal count value is 1.

[0131] On the other hand, the determining section 8c maintains the determination result of the sheet stack amount when the withdrawal count value is counted without changing it.

[0132] The determining unit 8c may determine the sheet stack amount based on the pull-out count value according to the same rule as that for determining the sheet stack amount based on the installation count value.

[0133] The determination unit 8c outputs the determination result of the stacked sheet amount to the display device 802. The determination unit 8c may also transmit the determination result of the stacked sheet amount through the communication device 83 to another device such as the host device.

[0134] By employing the sheet feeding device 1, it becomes possible to detect the remaining amount of sheets at multiple levels without increasing the number of photosensors 54. [Explanation of symbols]

[0135] 1: Sheet feeding device 2: Printing device 3: Sheet transport device 4: Image forming section 5: Sheet amount detection unit 8: Control device 9x: Target sheet 10: Image forming device 11: Lower body part 12: Sheet cassette 14: Delivery mechanism 51: Main moving part 52: Secondary movable member 54: Photosensor (object detection section) 80: CPU 511: Contact wall part 512: Main contact part 521: Sub-contact part 522: Detection part 540: Detection area 541: Light emitting part 542: Light detection unit

Claims

1. A main body portion, a sheet container that is attached to the main body portion so as to be capable of being pulled out along a reference direction and that is capable of stacking a plurality of sheets; a delivery mechanism for delivering the plurality of sheets one by one from the sheet container; a plurality of main movable members each supported by the sheet container so as to be movable between a first reference position and a first retracted position along the reference direction; a plurality of secondary movable members each supported by the main body portion so as to be movable between a second reference position and a second retracted position, and each brought into contact with the plurality of primary movable members when the sheet container is attached to the main body portion; a biasing portion that biases the plurality of secondary movable members toward the second reference position; an object detection unit supported by the main body, which detects an object present within a detection area within the main body, and outputs a detection signal; a determination unit that determines a sheet load amount in the sheet container based on a change in the detection signal, Each of the plurality of main movable members is a contact wall portion that is disposed in each of a plurality of layer regions having different heights in the sheet container and that contacts one end of the target sheet when the plurality of sheets includes one or more target sheets located at a corresponding height among the plurality of layer regions; a main contact portion that is disposed outside the sheet container and that contacts each of the plurality of secondary movable members when the sheet container is attached to the main body portion; Each of the plurality of secondary movable members is a sub-contact portion that contacts the main contact portion of each of the plurality of main movable members; one or more detection targets passing through the detection area in response to movement of each of the plurality of secondary movable members; The plurality of secondary movable members each have a different number of the detection portions, When the target sheet is not present, each of the plurality of main movable members is held at the first reference position by a force received from the biasing portion via each of the plurality of sub movable members, When the target sheet is present, each of the plurality of main movable members is held at the first retracted position by a force applied to the abutment wall portion from the target sheet, When the sheet container is attached to the main body, each of the plurality of auxiliary movable members moves from the second reference position to the second retracted position by a force that the auxiliary abutment portion receives from the main abutment portion when each of the plurality of corresponding main movable members is in the first retracted position, when the target sheet in each of the plurality of layer regions changes from a state in which the target sheet is present to a state in which the target sheet is not present under a condition in which the sheet container is attached to the main body portion, each of the plurality of secondary movable members corresponding to each of the plurality of layer regions whose state has changed moves from the second retracted position to the second reference position by a force of the biasing portion, when each of the plurality of secondary movable members moves from one of the second reference position and the second retracted position to the other, one or more of the detected portions of each of the plurality of secondary movable members pass through the detection area; The determination unit counts the number of rising transitions or falling transitions of the detection signal, and determines the sheet stack amount according to the count value.

2. a mounting sensor for detecting a mounting state of the sheet container in the main body, The sheet feeding apparatus according to claim 1 , wherein the determining section determines the sheet stack amount based on a detection result of the mounting sensor and the count value.

3. the object detection unit is a photosensor having a light emitting unit that emits detection light to the detection area along a cross direction that crosses the reference direction, and a light detection unit that detects the detection light passing through the detection area or reflected light of the detection light, 3. The sheet feeding device according to claim 1, wherein when all of the plurality of secondary movable members are positioned at the second reference position or the second retracted position, the plurality of detected portions of the plurality of secondary movable members are arranged so that the number of overlapping portions differs when viewed from the intersecting direction at multiple positions in the reference direction.

4. 3. The sheet feeding device according to claim 1, a printing device that forms an image on the sheet fed from the sheet feeding device.

Images