Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent non-detection of toner emptiness and continue suitable toner supply.SOLUTION: An image forming apparatus 1 comprises a developing device 40, a container 50, a toner supply device 60, and a control unit 8. The developing device 40 supplies toner to a photoreceptor drum. The container 50 stores the toner supplied to the developing device 40. The toner supply device 60 conveys and supplies the toner in the container 50 to the developing device 40. The control unit 8 detects emptiness of the toner in the container 50 by using a plurality of emptiness detection paths, and the plurality of emptiness detection paths have different emptiness detection conditions.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] In electrophotographic image forming apparatuses such as copiers and printers, an apparatus that develops an electrostatic latent image formed on the surface of a photoreceptor drum, which is an image carrier, with toner and then forms a toner image to be transferred onto paper is widely used. The toner is supplied to the developing device using a container that is detachable from the main body of the image forming apparatus.

[0003] In the conventional image forming apparatus disclosed in Patent Document 1, the toner stored in the toner container is supplied to the developing device via an intermediate conveyance path. Then, based on the empty detection of the toner by a detection unit disposed near the intermediate conveyance path and the driving time and driving history of a conveyance screw that conveys the toner in the intermediate conveyance path, the near-empty state of the toner container is determined. Thereby, the near-empty state of the toner container can be determined at an appropriate timing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above conventional image forming apparatus, when a defect occurs in the toner detection unit disposed near the intermediate conveyance path, or when toner stays around the detection unit and cannot move, there is a problem that the empty detection of the toner cannot be performed by the detection unit. Since the empty detection of the toner cannot be performed, suitable toner replenishment cannot be realized, and there is a concern that the productivity in image formation may decrease.

[0006] The present invention has been made in view of the above points, and an object thereof is to provide an image forming apparatus capable of suppressing undetected toner empty and continuing suitable toner supply.

Means for Solving the Problems

[0007] To solve the above problems, an image forming apparatus of the present invention includes a developing device, a container, a toner supply device, and a control unit. The developing device supplies toner to an image carrier. The container stores the toner to be supplied to the developing device. The toner supply device conveys and supplies the toner in the container to the developing device. The control unit controls the operations of the developing device and the toner supply device. The control unit detects the empty of the toner in the container using a plurality of empty detection paths, and the empty detection conditions in the plurality of empty detection paths are different.

Effects of the Invention

[0008] According to the configuration of the present invention, the toner remaining amount is detected using a plurality of empty detection paths, and even if a problem occurs in any of them, the empty of the toner can be detected by another path. Therefore, undetected toner empty can be suppressed, and suitable toner supply can be continued.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 12

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following content.

[0011] FIG. 1 is a schematic cross-sectional view of the image forming apparatus 1 according to the embodiment. FIG. 2 is a block diagram showing the schematic configuration of the image forming apparatus 1 of FIG. 1. FIG. 3 is a cross-sectional view around the image forming unit 20 of the image forming apparatus 1 of FIG. 1. As an example of the image forming apparatus 1 of the present embodiment, it is a tandem type color printer that transfers a toner image to a sheet S using an intermediate transfer belt 31. The image forming apparatus 1 may be a so-called multifunction machine having functions such as printing, scanning (image reading), and facsimile transmission.

[0012] As shown in FIGS. 1, 2, and 3, the image forming apparatus 1 includes a paper supply unit 3, a paper transport unit 4, an exposure unit 5, an image forming unit 20, a transfer unit 30, a fixing unit 6, a paper discharge unit 7, and a control unit 8 provided in its main body 2.

[0013] The main body 2 is provided with an operation panel 2c. The operation panel 2c is arranged, for example, at the upper front part of the main body 2 and includes a display unit 2d such as a liquid crystal display. The operation panel 2c displays, on the display unit 2d, an image of a screen related to settings such as printing conditions (such as the type and size of the paper S used for printing) and input of execution commands, etc., and directly receives the input from the user himself / herself. Further, the display unit 2d also serves as a notification unit for notifying the user of, for example, the state of the image forming apparatus 1, precautions, error messages, etc. by displaying them.

[0014] The paper supply unit 3 is arranged at the bottom of the main body 2. The paper supply unit 3 stores a plurality of sheets of paper S before printing and separates and feeds out the sheets of paper S one by one during printing. The paper conveyance unit 4 extends in the vertical direction along the side wall of the main body 2. The paper conveyance unit 4 conveys the sheet of paper S sent out from the paper supply unit 3 to the secondary transfer unit 33 and the fixing unit 6, and further discharges the sheet of paper S after fixing from the paper discharge port 4a to the paper discharge unit 7. The exposure unit 5 is arranged above the paper supply unit 3. The exposure unit 5 irradiates the image forming unit 20 with laser light controlled based on image data.

[0015] The image forming unit 20 is arranged above the exposure unit 5 and below the intermediate transfer belt 31. The image forming unit 20 includes an image forming unit 20Y for yellow, an image forming unit 20C for cyan, an image forming unit 20M for magenta, and an image forming unit 20B for black. The basic configurations of these four image forming units 20 are the same. Thus, in the following description, unless particularly limited, the identification symbols "Y", "C", "M", "B" representing each color may be omitted.

[0016] The image forming unit 20 includes a photosensitive drum (image carrier) 21 rotatably supported in a predetermined direction (clockwise in FIGS. 1 and 3). The image forming unit 20 further includes a charging unit 22 arranged along the rotation direction around the photosensitive drum 21, a developing device 40, and a drum cleaning unit 23. Note that a primary transfer unit 32 is arranged between the developing device 40 and the drum cleaning unit 23.

[0017] The photosensitive drum 21 is formed in a cylindrical shape extending in the horizontal direction and has a photosensitive layer on its outer peripheral surface. The charging unit 22 charges the surface (outer peripheral surface) of the photosensitive drum 21 to a predetermined potential. The exposure unit 5 exposes the outer peripheral surface of the photosensitive drum 21 charged by the charging unit 22 to form an electrostatic latent image of the document image on the outer peripheral surface of the photosensitive drum 21. The developing device 40 supplies toner to this electrostatic latent image for development to form a toner image. Each of the four image forming units 20 forms a toner image of a different color. The drum cleaning unit 23 removes and cleans the toner and the like remaining on the outer peripheral surface of the photosensitive drum 21 after the toner image is primarily transferred to the outer peripheral surface of the intermediate transfer belt 31. In this way, the image forming unit 20 forms an image (toner image) to be later transferred to the paper S.

[0018] The transfer unit 30 includes the intermediate transfer belt 31, primary transfer units 32Y, 32C, 32M, 32B, a secondary transfer unit 33, and a belt cleaning unit 34. The intermediate transfer belt 31 is disposed above the four image forming units 20. The intermediate transfer belt 31 is rotatably supported in a predetermined direction (counterclockwise in FIG. 1) and is an endless intermediate transfer body on which the toner images formed by each of the four image forming units 20 are sequentially superimposed and primarily transferred. The four image forming units 20 are arranged in a so-called tandem manner in a row from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 31.

[0019] The primary transfer units 32Y, 32C, 32M, 32B are disposed above the image forming units 20Y, 20C, 20M, 20B of each color with the intermediate transfer belt 31 interposed therebetween. The secondary transfer unit 33 is upstream of the fixing unit 6 with respect to the paper conveyance direction of the paper conveyance unit 4 and is disposed downstream of the four image forming units 20Y, 20C, 20M, 20B with respect to the rotation direction of the intermediate transfer belt 31. The belt cleaning unit 34 is disposed downstream of the secondary transfer unit 33 with respect to the rotation direction of the intermediate transfer belt 31.

[0020] The primary transfer unit 32 transfers the toner image formed on the outer peripheral surface of the photoreceptor drum 21 to the intermediate transfer belt 31. In other words, the toner image is primarily transferred to the outer peripheral surface of the intermediate transfer belt 31 at the primary transfer units 32Y, 32C, 32M, and 32B for each color. Then, as the intermediate transfer belt 31 rotates, the toner images of the four image forming units 20 are continuously and successively transferred to the intermediate transfer belt 31 at a predetermined timing, whereby a color toner image in which the toner images of yellow, cyan, magenta, and black are superimposed is formed on the outer peripheral surface of the intermediate transfer belt 31.

[0021] The color toner image on the outer peripheral surface of the intermediate transfer belt 31 is transferred to the sheet S that has been fed in synchronization by the sheet conveyance unit 4 at the secondary transfer nip formed in the secondary transfer unit 33. The belt cleaning unit 34 removes and cleans the deposits such as toner remaining on the outer peripheral surface of the intermediate transfer belt 31 after secondary transfer. In this way, the transfer unit 30 transfers (records) the toner image formed on the outer peripheral surface of the photoreceptor drum 21 to the sheet S.

[0022] The fixing unit 6 is disposed above the secondary transfer unit 33. The fixing unit 6 heats and presses the sheet S onto which the toner image has been transferred to fix the toner image on the sheet S.

[0023] The sheet discharge unit 7 is disposed above the transfer unit 30. The sheet S on which the toner image has been fixed and the printing is completed is conveyed to the sheet discharge unit 7. The printed sheet (printed matter) is taken out from the upper side of the sheet discharge unit 7.

[0024] The control unit 8 includes a CPU, an image processing unit, a storage unit, and other electronic circuits and components (all not shown). The CPU controls the operations of the respective components provided in the image forming apparatus 1 based on programs and data for control stored in the storage unit, and performs processing related to the functions of the image forming apparatus 1. Each of the paper supply unit 3, the paper conveyance unit 4, the exposure unit 5, the image forming unit 20, the transfer unit 30, and the fixing unit 6 receives individual commands from the control unit 8 and cooperatively performs printing on the paper S. The storage unit is composed of a combination of a non-volatile storage device such as a program ROM (Read Only Memory) and a data ROM, and a volatile storage device such as a RAM (Random Access Memory).

[0025] Subsequently, the developing device 40 and its peripheral configuration will be described with reference to FIG. 3. Since the basic configurations of the developing devices 40 for each color are the same, the description of the components with identification symbols representing each color and the explanation will be omitted.

[0026] The developing device 40 supplies toner to the outer peripheral surface of the photosensitive drum 21. The developing device 40 includes a developing container 41, a first agitation and conveyance member 42, a second agitation and conveyance member 43, a developing roller 44, a regulating member 45, and a toner density sensor (remaining developer detection unit) 46.

[0027] The developing container 41 has an elongated shape extending along the axial direction of the photosensitive drum 21 (the depth direction of the paper surface in FIG. 3), and is arranged with its longitudinal direction horizontal. The developing container 41 accommodates a two-component developer containing toner and a magnetic carrier as a developer containing toner to be supplied to the photosensitive drum 21. The developing container 41 has a partition portion 411, a first conveyance chamber 412, and a second conveyance chamber 413.

[0028] The partition portion 411 is provided at the lower part inside the developing container 41. The partition portion 411 is disposed at approximately the center in the direction (the left - right horizontal direction in FIG. 3) intersecting the axial direction at the lower part of the developing container 41, and extends in the axial direction and the vertical direction. The partition portion 411 divides the inside of the developing container 41 in the direction (the left - right direction in FIG. 3) intersecting the axial direction. The developing container 41 is provided with communication portions (not shown) between the first transport chamber 412 and the second transport chamber 413 on both end sides in the axial direction (the depth direction of the paper surface in FIG. 3) of the partition portion 411 respectively.

[0029] The first transport chamber 412 and the second transport chamber 413 are provided inside the developing container 41. The first transport chamber 412 and the second transport chamber 413 are formed by the inside of the developing container 41 being divided by the partition portion 411 and are juxtaposed to each other. The second transport chamber 413 is disposed adjacent to and below the arrangement region of the developing roller 44 inside the developing container 41. The first transport chamber 412 is disposed in a region inside the developing container 41 that is farther from the developing roller 44 than the second transport chamber 413. The first transport chamber 412 receives replenishment of the developer through the replenishment pipe connection portion 412a shown in FIG. 3.

[0030] The first stirring and transporting member 42 is disposed inside the first transport chamber 412. The second stirring and transporting member 43 is disposed inside the second transport chamber 413. The second stirring and transporting member 43 extends in parallel in proximity to the developing roller 44. The first stirring and transporting member 42 and the second stirring and transporting member 43 are rotatably supported by the developing container 41 about an axis extending parallel to the photoreceptor drum 21. The first stirring and transporting member 42 and the second stirring and transporting member 43 rotate about their axes to stir and transport the developer in opposite directions along the axial direction of the rotation while stirring.

[0031] Due to the rotation of the first stirring and transporting member 42 and the second stirring and transporting member 43, the developer circulates between the first transport chamber 412 and the second transport chamber 413 through the communication portions disposed at both end portions in the axial direction of the partition portion 411. In the first transport chamber 412 and the second transport chamber 413, the toner replenished from the outside is stirred and charged.

[0032] The developing roller 44 is located above the second stirring and conveying member 43 in the developing container 41 and is disposed opposite to the photosensitive drum 21. The developing roller 44 is rotatably supported by the developing container 41 about an axis extending parallel to the axis of the photosensitive drum 21.

[0033] A part of the outer peripheral surface of the developing roller 44 is exposed from the developing container 41, faces and is close to the photosensitive drum 21. The developing roller 44 carries the toner supplied to the outer peripheral surface of the photosensitive drum 21 on its outer peripheral surface in the facing area with the photosensitive drum 21. The developing roller 44 adheres the toner in the second conveyance chamber 413 to the electrostatic latent image on the outer peripheral surface of the photosensitive drum 21 to form a toner image.

[0034] The regulating member 45 is disposed on the upstream side in the rotation direction of the developing roller 44 in the facing area between the developing roller 44 and the photosensitive drum 21. The regulating member 45 faces close to the developing roller 44 and is disposed with a predetermined interval between its tip and the outer peripheral surface of the developing roller 44. The regulating member 45 extends over the entire region in the axial direction (the depth direction of the paper surface in FIG. 3) of the developing roller 44. The regulating member 45 regulates the layer thickness of the developer (toner) carried on the outer peripheral surface of the developing roller 44 passing through the gap between the tip of the regulating member 45 and the outer peripheral surface of the developing roller 44.

[0035] The toner density sensor 46 is disposed on the wall portion along the longitudinal direction of the first conveyance chamber 412. The toner density sensor 46 is disposed opposite to the first stirring and conveying member 42. In the present embodiment, a headless sensor is used as the toner density sensor 46. The toner density sensor 46 which is a headless sensor has its detection surface buried in the inner wall surface of the first conveyance chamber 412. The toner density sensor 46 detects the toner density in the developer.

[0036] Specifically, the toner density sensor 46 is a magnetic permeability detection type sensor that obtains the toner density (mixing ratio of toner T to carrier C in the developer; T / C) by detecting changes in the magnetic permeability of the two-component developer. If the ratio of toner to carrier in the developer within the first conveyance chamber 412 changes, the magnetic permeability also changes, and accordingly, the output signal of the toner density sensor 46 also changes.

[0037] Based on the output signal of the sensor received from the toner density sensor 46, the control unit 8 controls the start and stop of replenishment of the developer (toner and carrier) to the developing device 40 with respect to the toner empty detection path related to the developing device 40. That is, the toner density sensor 46 is a developing remaining amount detection unit that detects the remaining toner amount by detecting the toner density within the developing device 40, and it is a remaining toner amount detection unit. Thereby, a toner empty detection path related to the developing device 40 can be configured for control.

[0038] The toner in the developing container 41 is agitated, circulated, and charged by the first agitation conveyance member 42 and the second agitation conveyance member 43, and is carried on the outer peripheral surface of the developing roller 44 by the second agitation conveyance member 43. The developer carried on the outer peripheral surface of the developing roller 44 has its layer thickness regulated by the regulating member 45, and is then conveyed to the opposing region between the developing roller 44 and the photosensitive drum 21 by the rotation of the developing roller 44. When a predetermined developing voltage is applied to the developing roller 44, due to the potential difference with the potential of the surface (outer peripheral surface) of the photosensitive drum 21, the toner in the developer carried on the outer peripheral surface of the developing roller 44 moves to the outer peripheral surface of the photosensitive drum 21 in the opposing region. Thereby, the electrostatic latent image on the outer peripheral surface of the photosensitive drum 21 is developed with toner.

[0039] Regarding the replenishment of toner to the developing device 40, the image forming apparatus 1 includes a container 50 and a toner replenishing device 60 (see FIG. 4). The container 50 includes a first container 51 and a second container 52. The image forming apparatus 1 includes a plurality of containers 50 (the first container 51 and the second container 52) that store toner of the same color. In the following description, the first container 51 and the second container 52 may be collectively referred to as the "container 50".

[0040] The first container 51, the second container 52, and the toner replenishing device 60 are arranged above the developing device 40. The first container 51, the second container 52, and the toner replenishing device 60 are each provided one for each of the four colors of yellow, cyan, magenta, and black.

[0041] Subsequently, the configurations of the container 50 and the toner replenishing device 60 will be described with reference to FIGS. 4 to 9. FIG. 4 is a perspective view of the periphery of the toner replenishing device 60 of the image forming apparatus 1 in FIG. 1. FIGS. 5 and 6 are front views and side views of the periphery of the toner replenishing device 60 in FIG. 4. FIGS. 7 and 8 are perspective views and plan views of the toner replenishing device 60 in FIG. 4. FIG. 9 is a perspective view of the first transfer pipe 65 and the second transfer pipe 66 of the toner replenishing device 60 in FIG. 7.

[0042] The first container 51, the second container 52, and the toner replenishing device 60 include a first container 51Y, a second container 52Y, and a toner replenishing device 60Y for yellow, a first container 51C, a second container 52C, and a toner replenishing device 60C for cyan, a first container 51M, a second container 52M, and a toner replenishing device 60M for magenta, and a first container 51B, a second container 52B, and a toner replenishing device 60B for black. The first container 51, the second container 52, and the toner replenishing device 60 for each of these colors have the same basic configuration. Accordingly, in the following description, the identification symbols "Y", "C", "M", and "B" representing each color may be omitted unless otherwise particularly limited.

[0043] The first container 51 is disposed above the second container 52. The second container 52 is disposed below the first container 51. The first container 51 and the second container 52 are displaced in the arrangement direction of the image forming unit 20 and the toner supply device 60 when viewed from the front. The first container 51 and the second container 52 are detachable from the main body 2 and accommodate toner to be supplied to the developing device 40.

[0044] The first container 51 and the second container 52 are in an elongated cylindrical shape extending along the axial direction Dx of the photosensitive drum 21, and are arranged with their longitudinal directions horizontal. On the peripheral walls of the first container 51 and the second container 52, spiral protrusions 51s, 52s that protrude radially inward and extend in the longitudinal direction are formed.

[0045] One end side (front side) in the axial direction Dx of the first container 51 and the second container 52 is closed, and the other end side (rear side) has an opening (not shown). The first container 51 and the second container 52 are connected to the first container connection portion 61 and the second container connection portion 62 of the toner supply device 60 on the rear side which is the opening side. The first container 51 and the second container 52 are supported by the toner supply device 60 so as to be rotatable about an axis extending parallel to the axial direction Dx of the photosensitive drum 21.

[0046] The first container 51 and the second container 52 are rotated about an axis extending parallel to the axial direction Dx of the photosensitive drum 21 by a drive unit (not shown) of the toner supply device 60. When the first container 51 and the second container 52 rotate, the internal toner is sent toward the rear side which is the opening side by the spiral protrusions 51s, 52s. Thereby, the toner inside each of the first container 51 and the second container 52 flows into the toner supply device 60 from the opening.

[0047] The toner supply device 60 is disposed behind the first container 51 and the second container 52. The four toner supply devices 60 are juxtaposed in a row in the same order as the four image forming units 20. The toner supply device 60 rotates the first container 51 and the second container 52 to supply the toner in the first container 51 and the second container 52 to the developing device 40.

[0048] The toner supply device 60 includes a first container connection portion 61, a second container connection portion 62, a first vertical pipe 63, a second vertical pipe 64, a first transfer pipe 65, a second transfer pipe 66, a first transfer member 67, a second transfer member 68, a supply pipe 69, a transfer drive portion 70, an intermediate remaining amount detection portion 71, and a rotation detection portion 80.

[0049] The first container connection portion 61 is at the upper part of the toner supply device 60 and is disposed above the second container connection portion 62. The first container connection portion 61 has a toner flow passage (not shown) inside. The first container connection portion 61 is connected to the opening side of the first container 51 and rotatably supports the first container 51. The downstream end in the toner flow direction of the first container connection portion 61 is connected to the first vertical pipe 63. When the toner in the first container 51 is supplied to the developing device 40, the toner flows from the first container 51 into the first container connection portion 61 and flows out through the first container connection portion 61 toward the first vertical pipe 63.

[0050] The second container connection portion 62 is at the upper part of the toner supply device 60 and is disposed below the first container connection portion 61. The second container connection portion 62 has a toner flow passage (not shown) inside. The second container connection portion 62 is connected to the opening side of the second container 52 and rotatably supports the second container 52. The downstream end in the toner flow direction of the second container connection portion 62 is connected to the second vertical pipe 64. When the toner in the second container 52 is supplied to the developing device 40, the toner flows from the second container 52 into the second container connection portion 62 and flows out through the second container connection portion 62 toward the second vertical pipe 64.

[0051] The first vertical pipe 63 is disposed between the first container connection portion 61 and the first transfer pipe 65. The first vertical pipe 63 is formed in a cylindrical shape extending in the vertical direction. The upper end of the first vertical pipe 63 is connected to the first container connection portion 61. The lower end of the first vertical pipe 63 is connected to the first transfer pipe 65. When the toner in the first container 51 is supplied to the developing device 40, the toner flows into the first vertical pipe 63 from the first container connection portion 61, passes through the first vertical pipe 63, and flows out toward the first transfer pipe 65.

[0052] The second vertical pipe 64 is disposed between the second container connection portion 62 and the second transfer pipe 66. The second vertical pipe 64 is formed in a cylindrical shape extending in the vertical direction. The upper end of the second vertical pipe 64 is connected to the second container connection portion 62. The lower end of the second vertical pipe 64 is connected to the second transfer pipe 66. When the toner in the second container 52 is supplied to the developing device 40, the toner flows into the second vertical pipe 64 from the second container connection portion 62, passes through the second vertical pipe 64, and flows out toward the second transfer pipe 66.

[0053] Since the first container 51 and the first container connection portion 61 are disposed above the second container 52 and the second container connection portion 62, the first vertical pipe 63 is longer in the vertical direction than the second vertical pipe 64. Since the second container 52 and the second container connection portion 62 are disposed below the first container 51 and the first container connection portion 61, the second vertical pipe 64 is shorter in the vertical direction than the first vertical pipe 63. The first vertical pipe 63 and the second vertical pipe 64 are disposed at the same position in the axial direction Dx of the photosensitive drum 21. In other words, the first vertical pipe 63 and the second vertical pipe 64 are juxtaposed on a straight line orthogonal to the axial direction Dx.

[0054] The first transfer pipe 65 is disposed between the first vertical pipe 63 and the supply pipe 69 in the vertical direction. The first transfer pipe 65 is formed in a cylindrical shape extending in the horizontal direction. One end side in the extending direction of the first transfer pipe 65 is connected to the first vertical pipe 63. The other end portion in the extending direction of the first transfer pipe 65 is connected to the confluence portion 60a. When the toner in the first container 51 is supplied to the developing device 40, the toner flows into the first transfer pipe 65 from the first vertical pipe 63, passes through the first transfer pipe 65, and flows out toward the confluence portion 60a. In other words, the first transfer pipe 65 is connected between the first container 51 and the supply pipe 69, and the toner is conveyed from the first container 51 side toward the supply pipe 69 side.

[0055] The second transfer pipe 66 is disposed between the second vertical pipe 64 and the supply pipe 69 in the vertical direction. The second transfer pipe 66 is formed in a cylindrical shape extending in the horizontal direction. One end side in the extending direction of the second transfer pipe 66 is connected to the second vertical pipe 64. The other end portion in the extending direction of the second transfer pipe 66 is connected to the confluence portion 60a. When the toner in the second container 52 is supplied to the developing device 40, the toner flows into the second transfer pipe 66 from the second vertical pipe 64, passes through the second transfer pipe 66, and flows out toward the confluence portion 60a. In other words, the second transfer pipe 66 is connected between the second container 52 and the supply pipe 69, and the toner is conveyed from the second container 52 side toward the supply pipe 69 side.

[0056] The first transfer pipe 65 and the second transfer pipe 66 are arranged in a direction (horizontal direction) intersecting with each other's extending directions so as to merge at the confluence portion 60a to which the supply pipe 69 is connected. In other words, the first transfer pipe 65 and the second transfer pipe 66 are arranged such that their extension lines intersect on the confluence portion 60a side of each other's extending directions. The first transfer pipe 65 and the second transfer pipe 66 have an acute angle in the horizontal direction between their extending directions and are arranged in a V shape when viewed from the vertical direction.

[0057] The first conveying member 67 is disposed within the first conveying pipe 65. The first conveying member 67 includes a rotating shaft provided between both axial ends of the cylindrical first conveying pipe 65, and first conveying blades formed on the outer peripheral surface of the rotating shaft and extending spirally along the axial direction. The first conveying member 67 is supported rotatably about an axis extending in the horizontal direction within the first conveying pipe 65. One axial end portion of the first conveying member 67 is located within the confluence portion 60a.

[0058] By rotating about its axis, the first conveying member 67 conveys the toner within the first conveying pipe 65 while stirring it along the toner conveying direction f1 (see FIGS. 8 and 9) parallel to the rotation axis. The first conveying member 67 conveys the toner within the first conveying pipe 65 from the side of the first vertical pipe 63 toward the confluence portion 60a side. In other words, the first conveying member 67 conveys the toner from the side of the first container 51 toward the supply pipe 69 side.

[0059] The second conveying member 68 is disposed within the second conveying pipe 66. The second conveying member 68 includes a rotating shaft provided between both axial ends of the cylindrical second conveying pipe 66, and second conveying blades formed on the outer peripheral surface of the rotating shaft and extending spirally along the axial direction. The second conveying member 68 is supported rotatably about an axis extending in the horizontal direction within the second conveying pipe 66. One axial end portion of the second conveying member 68 is located within the confluence portion 60a.

[0060] By rotating about its axis, the second conveying member 68 conveys the toner within the second conveying pipe 66 while stirring it along the toner conveying direction f2 (see FIGS. 8 and 9) parallel to the rotation axis. The second conveying member 68 conveys the toner within the second conveying pipe 66 from the side of the second vertical pipe 64 toward the confluence portion 60a side. In other words, the second conveying member 68 conveys the toner from the side of the second container 52 toward the supply pipe 69 side.

[0061] As described above, the first conveying pipe 65 and the second conveying pipe 66 are arranged in a V shape when viewed from the vertical direction. That is, the rotation axis of the first conveying member 67 and the rotation axis of the second conveying member 68 are arranged with a predetermined axis angle α.

[0062] The supply pipe 69 is arranged at the lower part of the toner supply device 60. The toner supply device 60 includes a single supply pipe 69. The supply pipe 69 is formed in a cylindrical shape extending in the vertical direction. The upper end of the supply pipe 69 is connected to a confluence portion 60a where the first transfer pipe 65 and the second transfer pipe 66 merge. The lower end of the supply pipe 69 is connected to a supply pipe connection portion 412a of the developing device 40. When the toner in the first container 51 and the second container 52 is supplied to the developing device 40, the toner flows into the supply pipe 69 from the confluence portion 60a, and flows into the developing device 40 through the supply pipe 69.

[0063] The conveyance drive unit 70 is at the rear part of the toner supply device 60 and is arranged on the upstream side in the toner conveyance direction of the first transfer pipe 65 and the second transfer pipe 66. The conveyance drive unit 70 includes a motor 70m and a gear group 70g composed of a plurality of gears. The motor 70m is connected to each of the first conveyance member 67 and the second conveyance member 68 via the gear group 70g. The conveyance drive unit 70 selectively rotates one of the first conveyance member 67 and the second conveyance member 68 by rotating the motor 70m in the forward and reverse directions respectively.

[0064] The intermediate remaining amount detection unit 71 includes a first intermediate remaining amount detection unit 71A and a second intermediate remaining amount detection unit 71B. The first intermediate remaining amount detection unit 71A is arranged at the lower part of the first vertical pipe 63. The second intermediate remaining amount detection unit 71B is arranged at the lower part of the second vertical pipe 64. The first intermediate remaining amount detection unit 71A and the second intermediate remaining amount detection unit 71B are composed of permeability detection type sensors similar to the toner concentration sensor 46. The first intermediate remaining amount detection unit 71A detects a change in the permeability of the two-component developer at the lower part of the first vertical pipe 63 and outputs a detection signal. The second intermediate remaining amount detection unit 71B detects a change in the permeability of the two-component developer at the lower part of the second vertical pipe 64 and outputs a detection signal.

[0065] The control unit 8 controls the start and stop of replenishing the developing device 40 with the developer based on the output signals of the sensors received from the first intermediate remaining amount detection unit 71A and the second intermediate remaining amount detection unit 71B regarding the toner empty detection path of the toner supply device 60. That is, the first intermediate remaining amount detection unit 71A and the second intermediate remaining amount detection unit 71B are toner remaining amount detection units that detect the toner remaining amount on the toner supply path of the toner supply device 60. Thereby, a toner empty detection path of the toner supply device 60 in terms of control can be configured.

[0066] The rotation detection unit 80 is disposed at the rear of the toner supply device 60 and on the upstream side in the toner conveyance direction with respect to the conveyance drive unit 70. The rotation detection unit 80 includes a container remaining amount detection unit 81 and a light shielding plate (not shown) that rotates individually together with each of the first conveyance member 67 and the second conveyance member 68.

[0067] The container remaining amount detection unit 81 is, for example, a light transmission type sensor, includes a light emitting unit and a light receiving unit, and has an optical path from the light emitting unit toward the light receiving unit. The light shielding plate enters and retreats on the optical path of the light transmission type sensor. The container remaining amount detection unit 81 detects the rotation of the first conveyance member 67 and the second conveyance member 68 and outputs a detection signal.

[0068] The control unit 8 detects the remaining amount of toner in the first container 51 and the second container 52 based on the output signal of the sensor received from the container remaining amount detection unit 81 regarding the toner empty detection path of the container 50. Specifically, the control unit 8 counts the rotation speeds of the first conveyance member 67 and the second conveyance member 68 based on the output signal from the container remaining amount detection unit 81, and detects the remaining amount of toner in the first container 51 and the second container 52 based on the rotation speeds. That is, the container remaining amount detection unit 81 is a toner remaining amount detection unit that detects the toner remaining amount in the container 50. Thereby, a toner empty detection path of the container 50 in terms of control can be configured.

[0069] Next, the toner empty detection path will be described. The image forming apparatus 1 includes, for control purposes, a plurality of toner empty detection paths. In the present embodiment, the image forming apparatus 1 includes three toner empty detection paths. Specifically speaking, the control unit 8 uses the toner empty detection paths related to the developing device 40, the toner supply device 60, and the container 50 to detect the emptiness of the toner in the container 50.

[0070] According to the above configuration, even if a problem occurs in any of the toner empty detection paths related to the developing device 40, the toner supply device 60, and the container 50, the emptiness of the toner can be detected by another path. Therefore, in the image forming apparatus 1, it is possible to suppress the non-detection of toner empty, and it is possible to continue suitable toner supply. Note that the control related to the three toner empty detection paths is processed in parallel.

[0071] Next, the processing flow of the toner empty detection path related to the developing device 40 will be described. FIG. 10 is a flowchart showing an example of the processing of the toner empty detection path related to the developing device 40.

[0072] When the operation of the image forming apparatus 1 is started, monitoring of the toner state is started in the toner empty detection path related to the developing device 40 ("Start" in FIG. 10). Then, the control unit 8 determines whether the developing device 40 is in a normal state (step S101). If the developing device 40 is in a normal state (Yes in step S101), the process proceeds to step S102. If the developing device 40 is not in a normal state (No in step S101), the process proceeds to step S103.

[0073] The control unit 8 determines whether the forced toner supply has failed four times in the developing device 40, or whether the forced toner supply has failed and the toner consumption amount is 70% or more (step S102). If these conditions are met (Yes in step S102), the process proceeds to step S103. If these conditions are not met (No in step S102), the determination in step S102 is made again.

[0074] Here, the forced toner replenishment of the developing device 40 will be described. The forced toner replenishment of the developing device 40 is executed when the toner concentration (mixing ratio of toner T to carrier C in the developer; T / C) detected by the toner concentration sensor (developer remaining amount detection unit) 46 is 2% lower than the target. If the forced toner replenishment is successful, the control unit 8 returns the state of the developing device 40 to the normal state. Even if the forced toner replenishment fails, if the toner concentration is not lower than 2% of the target, the control unit 8 executes the forced toner replenishment when the toner concentration is 2% lower than the target.

[0075] Also, when the developing device 40 enters the warm-up operation in the toner low state (the toner remaining amount is less than a predetermined value), the control unit 8 executes the forced toner replenishment during the warm-up operation. The forced toner replenishment of the developing device 40 may be interrupted by opening and closing the exterior cover (not shown) of the image forming apparatus 1. In this case, the forced replenishment is restarted when the cover is closed. Also, the number of times of forced toner replenishment to the developing device 40 is stored and maintained in a storage unit or the like even when the image forming apparatus 1 is powered off.

[0076] In the developing device 40, when the forced toner replenishment fails four times, or when the forced toner replenishment fails and the toner consumption amount is 70% or more, the control unit 8 determines whether the other container 50 for the in-use container 50 among the first container 51 and the second container 52 that store the same color toner is empty, or whether the other container 50 itself is not installed in the image forming apparatus 1 (step S103).

[0077] Note that when moving to step S103, the control unit 8 displays caution messages such as "Toner low state" and "Shake the container" on the display unit 2d of the main body 2.

[0078] When another container 50 for the container 50 in use is not empty or another container 50 itself is mounted (No in step S103), the control unit 8 switches the toner supply path to another container 50 (step S104). That is, when the control unit 8 detects that the toner in the container 50 in use is empty, it switches the toner supply path to another container 50 of the same color. This enables the toner supply operation to be performed smoothly.

[0079] When switching the toner supply path to another container 50, if the intermediate remaining amount detection unit 71 has previously detected that the toner is empty, the control unit 8 starts supplying toner to the toner supply device 60. Also, when switching the toner supply path to another container 50, if the developing device 40 was previously in a toner-low state, the control unit 8 starts forced toner supply to the developing device 40. Further, when the toner supply path is switched to another container 50, the control unit 8 clears the number of times of forced toner supply to the developing device 40 stored in the storage unit or the like.

[0080] When another container 50 for the container 50 in use is empty or another container 50 itself is not mounted (Yes in step S103), the control unit 8 determines whether it is either a printing rate of 200% and printing 40 sheets, or whether toner forced supply has failed, or whether the intermediate remaining amount detection unit 71 has detected that the toner is empty (step S105). If these conditions are met (Yes in step S105), the process proceeds to step S106, and if these conditions are not met (No in step S105), the determination in step S103 is performed again.

[0081] When the conditions in step S105 are met, the control unit 8 determines that the toner is empty and stops supplying toner from the container 50 to the developing device 40 (step S106). Then, the control unit 8 ends the process according to FIG. 10.

[0082] When moving to step S106, the control unit 8 displays precautions and messages such as "Toner Empty Notification / Device Stop" and "Please Replace the Container" on the display unit 2d of the main body 2.

[0083] Subsequently, the processing flow of the toner empty detection path related to the toner supply device 60 will be described. FIG. 11 is a flowchart showing an example of the processing of the toner empty detection path related to the toner supply device 60.

[0084] When the operation of the image forming apparatus 1 is started, monitoring of the toner state is started in the toner empty detection path related to the toner supply device 60 ("Start" in FIG. 11). Then, the control unit 8 determines whether the toner supply device 60 is in a normal state (step S201). If the toner supply device 60 is in a normal state (Yes in step S201), the process proceeds to step S202. If the toner supply device 60 is not in a normal state (No in step S201), the process proceeds to step S203.

[0085] In the toner supply device 60, the control unit 8 determines whether the intermediate remaining amount detection unit 71 detects toner empty and whether the toner consumption amount is 70% or more (step S202). If this condition is satisfied (Yes in step S202), the process proceeds to step S203. If this condition is not satisfied (No in step S202), the determination in step S202 is performed again.

[0086] In the toner supply device 60, when the intermediate remaining amount detection unit 71 detects toner empty and the toner consumption amount is 70% or more, the control unit 8 determines whether the other container 50 for the in-use container 50 among the first container 51 and the second container 52 that store the same color toner is empty, or whether the other container 50 itself is not mounted on the image forming apparatus 1 (step S203).

[0087] When moving to step S203, the control unit 8 displays cautions and messages such as "Toner Low" and "Please Shake the Container" on the display unit 2d of the main body 2.

[0088] When another container 50 for the container 50 in use is not empty or another container 50 itself is mounted (No in step S203), the control unit 8 switches the toner supply path to another container 50 (step S204). That is, when the control unit 8 detects that the toner in the container 50 in use is empty, it switches the toner supply path to another container 50 of the same color. This enables smooth toner supply operation.

[0089] When switching the toner supply path to another container 50, if the intermediate remaining amount detection unit 71 has previously detected toner empty, the control unit 8 starts supplying toner to the toner supply device 60. Also, when the intermediate remaining amount detection unit 71 detects that the toner is full along with the switching of the toner supply path to another container 50, the control unit 8 sets the state of the toner supply device 60 to the normal state.

[0090] When another container 50 for the container 50 in use is empty or another container 50 itself is not mounted (Yes in step S203), the control unit 8 determines whether it is either a printing rate of 200% or printing 40 sheets (step S205). If this condition is met (Yes in step S205), it moves to step S206. If this condition is not met (No in step S205), the determination in step S203 is made again.

[0091] When the condition in step S205 is met, the control unit 8 determines that the toner is empty and stops supplying toner from the container 50 to the developing device 40 (step S206). Then, the control unit 8 ends the process according to FIG. 11.

[0092] When moving to step S206, the control unit 8 displays precautions and messages such as "Toner Empty Notification / Device Stop" and "Please Replace the Container" on the display unit 2d of the main body 2.

[0093] Subsequently, the processing flow of the toner empty detection path related to the container 50 will be described. FIG. 12 is a flowchart showing an example of the processing of the toner empty detection path related to the container 50.

[0094] When the operation of the image forming apparatus 1 is started, monitoring of the toner state is started in the toner empty detection path related to the container 50 ("Start" in FIG. 12). Then, the control unit 8 determines whether the container 50 is in a normal state (step S301). If the container 50 is in a normal state (Yes in step S301), the process proceeds to step S302, and if the container 50 is not in a normal state (No in step S301), the process proceeds to step S303.

[0095] The control unit 8 determines whether the toner consumption amount has reached a specified value in the container 50 (step S302). If the toner consumption amount has reached the specified value (Yes in step S302), the process proceeds to step S303, and if the toner consumption amount has not reached the specified value (No in step S302), the determination in step S302 is performed again.

[0096] When the toner consumption amount has reached the specified value in the container 50, the control unit 8 determines whether the forced replenishment of toner in the developing device 40 has failed or whether the intermediate remaining amount detection unit 71 has detected toner empty (step S303). If these conditions are met (Yes in step S303), the process proceeds to step S304, and if these conditions are not met (No in step S303), the determination in step S303 is performed again.

[0097] When moving to step S303, the control unit 8 displays precautions and messages such as "Toner Low State" and "Shake the Container" on the display unit 2d of the main body 2.

[0098] When the forced replenishment of toner in the developing device 40 fails or the intermediate remaining amount detection unit 71 detects that the toner is empty, the control unit 8 determines whether the other container 50 for the container 50 in use is empty or whether the other container 50 itself is not mounted on the image forming apparatus 1, among the first container 51 and the second container 52 that store the toner of the same color (step S304).

[0099] When the other container 50 for the container 50 in use is not empty or the other container 50 itself is mounted (No in step S304), the control unit 8 switches the toner supply path to the other container 50 (step S305). That is, when the control unit 8 detects that the toner in the container 50 in use is empty, it switches the toner supply path to the other container 50 of the same color. As a result, it becomes possible to smoothly perform the toner supply operation.

[0100] When switching the toner supply path to the other container 50, if the intermediate remaining amount detection unit 71 has previously detected that the toner is empty, the control unit 8 starts supplying toner to the toner supply device 60. Also, when switching the toner supply path to the other container 50, if the developing device 40 was previously in a toner shortage state, the control unit 8 starts forced replenishment of toner to the developing device 40. Further, when the toner supply path is switched to the other container 50, the control unit 8 clears the number of times of forced replenishment of toner to the developing device 40 stored in the storage unit or the like.

[0101] Also, when the exterior cover of the image forming apparatus 1 is opened and closed with the switching of the toner supply path to the other container 50 and the toner consumption amount of the container 50 becomes less than the specified value, the control unit 8 sets the state of the container 50 to the normal state. Also, when there is no tag on the other container 50 to which the toner supply path is switched or when the other container 50 is a non-genuine container, the control unit 8 sets the state of the container 50 to the normal state.

[0102] Also, when another container 50 for the container 50 in use is empty or the other container 50 itself is not attached (Yes in step S304), the control unit 8 determines that the toner is empty and stops supplying toner from the container 50 to the developing device 40 (step S306). Then, the control unit 8 ends the process according to FIG. 12.

[0103] Note that when moving to step S306, the control unit 8 displays precautions and messages such as "Toner Empty Notification / Device Stop" and "Please replace the container" on the display unit 2d of the main body 2.

[0104] As described above, the control unit 8 detects the emptiness of the toner in the container 50 using the toner empty detection paths related to the three components: the developing device 40, the toner supply device 60, and the container 50. Moreover, the empty detection conditions in these three empty detection paths are different. Thereby, it is possible to detect the emptiness of the toner corresponding to the characteristics of each of the developing device 40, the toner supply device 60, and the container 50. That is, in these three empty detection paths, it becomes possible to suitably detect the emptiness of the toner in the container 50. Therefore, in the image forming apparatus 1, suitable toner supply can be realized, and it becomes possible to improve the productivity in image formation.

[0105] And when the control unit 8 detects the emptiness of the toner in at least one of the three toner empty detection paths of the developing device 40, the toner supply device 60, and the container 50, it determines that the toner is empty. According to this configuration, when the emptiness of the toner is detected in any of the three toner empty detection paths, in the image forming apparatus 1, the emptiness of the toner is immediately determined. Thereby, the effect of suppressing the non-detection of toner empty can be enhanced.

[0106] Further, when the control unit 8 detects toner empty in the empty detection paths of a plurality of toners, it determines that the toner is empty. According to this configuration, the detection accuracy of toner empty can be improved. Therefore, undetected toner empty can be suppressed, and suitable toner replenishment can be continued.

[0107] As described above, the embodiments of the present invention have been described. However, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention.

[0108] For example, in the above embodiment, the image forming apparatus 1 is a so-called tandem type color printing image forming apparatus that sequentially forms images of a plurality of colors. However, the image forming apparatus is not necessarily limited to such a model. The image forming apparatus may be a color printing image forming apparatus that is not of the tandem type or a monochrome printing image forming apparatus.

Industrial Applicability

[0109] The present invention can be used in a toner replenishing device and an image forming apparatus.

Explanation of Signs

[0110] 1 Image forming apparatus 2d Display unit 8 Control unit 20 Image forming unit 21 Photoconductor drum (image carrier) 30 Transfer unit 31 Intermediate transfer belt 40 Developing device 41 Developing container 44 Developing roller 46 Toner density sensor (toner remaining amount detection unit) 50 Container 51 First container 52 Second container 60 Toner replenishing device 70 Conveying drive unit 71 Intermediate remaining amount detection unit (toner remaining amount detection unit) 71A First Intermediate Remaining Amount Detection Unit 71B Second Intermediate Remaining Amount Detection Unit 80 Rotation Detection Unit 81 Container Remaining Amount Detection Unit (Toner Remaining Amount Detection Unit) S Paper

Claims

1. An image forming apparatus comprising: a developing device that supplies toner to an image carrier; a container that stores the toner supplied to the developing device; a toner supply device that conveys and supplies the toner in the container to the developing device; a control unit that controls operations of the developing device and the toner supply device; wherein the control unit detects emptiness of the toner in the container using a plurality of empty detection paths, and empty detection conditions in the plurality of empty detection paths are different.

2. The image forming apparatus according to claim 1, further comprising at least three of the empty detection paths.

3. The image forming apparatus according to claim 1, further comprising a plurality of the containers that store toner of the same color, wherein when detecting emptiness of the toner in the container in use, the control unit switches a toner supply path to another container of the same color.

4. The image forming apparatus according to claim 1, wherein when detecting emptiness of the toner in at least one of the plurality of empty detection paths, the control unit determines emptiness of the toner.

5. The image forming apparatus according to claim 4, wherein when detecting emptiness of the toner in the plurality of empty detection paths, the control unit determines emptiness of the toner.

6. The image forming apparatus according to claim 1, further comprising a toner remaining amount detection unit that is disposed at a plurality of locations of the container, the toner supply device, and the developing device and detects a remaining amount of toner, wherein the control unit detects emptiness of the toner in the container using the plurality of empty detection paths based on a detection result of the toner remaining amount detection unit.

7. The image forming apparatus according to claim 6, wherein the toner remaining amount detection unit is disposed for each of the container, the toner supply device, and the developing device.

8. The image forming apparatus according to claim 6, wherein the toner remaining amount detection unit includes a developing remaining amount detection unit that detects the remaining amount of toner by detecting a toner concentration in the developing device.

9. The image forming apparatus according to claim 6, wherein the toner remaining amount detection unit includes an intermediate remaining amount detection unit that detects the remaining amount of toner on a toner supply path of the toner supply device.

10. The image forming apparatus according to claim 6, wherein the toner remaining amount detection unit includes a container remaining amount detection unit that detects the remaining amount of the toner in the container.

Images