Image forming apparatus

Abstract

To provide an image forming apparatus which is capable of suppressing supply stop of toner to a developing device and continuing suitable image forming.SOLUTION: An image forming apparatus 1 includes a developing device 40, a container 50, a toner supply device 60, a toner transportation detection unit, and a control part 8. The toner supply device 60 has a plurality of toner supply routes which transport the toner in the container 50 to the developing device 40 and supplies the same. The toner transportation detection unit detects a transportation error in toner transportation using the plurality of toner supply routes. When the toner transportation detection unit detects the transportation error of the toner in a toner supply route in use, The control part 8 switches the toner supply route to another toner supply route and transports the toner.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Electrophotographic image forming devices such as copiers and printers widely use devices that develop electrostatic latent images formed on the surface of a photosensitive drum, which serves as an image carrier, with toner to form a toner image that is later transferred to paper. The toner is replenished to the developing device using a container that is detachable from the image forming device main body.

[0003] The conventional image forming apparatus disclosed in Patent Document 1 has two toner bottles containing toner for one developing device. This allows the apparatus to continue image formation by supplying toner from the other toner bottle even if one toner bottle becomes empty. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-157350 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional image forming devices, if a toner transport error occurs in one toner supply path, the toner supply path cannot be switched to the other toner supply path, which causes the toner supply to the developing device to stop, making it necessary to halt operation of the image forming device, and raising concerns about reduced printing productivity.

[0006] The present invention has been made in consideration of the above points, and aims to provide an image forming apparatus that can suppress the cessation of toner supply to a developing device and continue to form suitable images. [Means for solving the problem]

[0007] In order to solve the above problems, the image forming apparatus of the present invention includes a developing device, a container, a toner supply device, a toner transport detection unit, and a control unit. The developing device supplies toner to an image carrier. The container stores the toner to be replenished to the developing device. The toner supply device has multiple toner supply paths that transport the toner in the container to the developing device for replenishment. The toner transport detection unit detects a transport error in toner transport using the multiple toner supply paths. The control unit controls the operation of the developing device and the toner supply device. When the toner transport detection unit detects a toner transport error in the toner supply path currently in use, the control unit switches to another toner supply path to transport the toner. [Effects of the Invention]

[0008] According to the configuration of the present invention, a toner transport error is detected when multiple toner supply paths are used, and even if a transport error occurs in one of the supply paths, the toner can be switched to another supply path and the toner transport and supply can be continued. Therefore, it is possible to prevent the toner supply to the developing device from being stopped, and to continue forming suitable images. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of the image forming apparatus of FIG. 1. [Figure 3] 2 is a cross-sectional view of the periphery of an image forming unit of the image forming apparatus of FIG. 1. [Figure 4] FIG. 2 is a perspective view of the periphery of a toner supply device of the image forming apparatus of FIG. [Figure 5] FIG. 5 is a front view of the toner supply device and its surroundings shown in FIG. [Figure 6] FIG. 5 is a side view of the toner supply device and its surroundings shown in FIG. [Figure 7]FIG. 5 is a perspective view of the toner supply device of FIG. [Figure 8] FIG. 5 is a plan view of the toner supply device of FIG. [Figure 9] 8 is a perspective view of a first conveying pipe and a second conveying pipe of the toner supply device of FIG. 7. FIG. [Figure 10] 10 is a flowchart illustrating an example of a general process for detecting a toner transport error for a plurality of toner supply paths. [Figure 11] 10 is a flowchart showing a first example of a process for detecting a toner transport error for a plurality of toner supply paths. [Figure 12] 10 is a flowchart showing a second example of a process for detecting a toner transport error for a plurality of toner supply paths. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following.

[0011] FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 according to an embodiment. FIG. 2 is a block diagram showing a schematic configuration of the image forming apparatus 1 shown in FIG. 1. FIG. 3 is a cross-sectional view of the periphery of an image forming unit 20 of the image forming apparatus 1 shown in FIG. 1. An example of the image forming apparatus 1 according to this embodiment is a tandem color printer that transfers a toner image onto paper S using an intermediate transfer belt 31. The image forming apparatus 1 may be a so-called multifunction peripheral that has functions such as printing, scanning (image reading), and facsimile transmission.

[0012] As shown in Figures 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, which are provided in its main body 2.

[0013] The main body 2 is equipped with an operation panel 2c. The operation panel 2c is located, for example, at the upper front 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 images of screens related to setting printing conditions such as the type and size of paper S to be used for printing and inputting execution commands, and receives these inputs directly from the user. Furthermore, the display unit 2d also serves as a notification unit that notifies the user of the status of the image forming apparatus 1, precautions, error messages, etc., by displaying them.

[0014] The paper supply unit 3 is located at the bottom of the main body 2. The paper supply unit 3 stores multiple sheets of paper S before printing, and separates and sends out the sheets S one by one during printing. The paper transport unit 4 extends vertically along the side wall of the main body 2. The paper transport unit 4 transports the paper S sent out from the paper supply unit 3 to the secondary transfer unit 33 and the fixing unit 6, and then ejects the paper S after fixing from the paper outlet 4a to the paper discharge unit 7. The exposure unit 5 is located 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 units 20 are disposed above the exposure unit 5 and below the intermediate transfer belt 31. The image forming units 20 include 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. These four image forming units 20 have the same basic configuration. Therefore, in the following description, the identification symbols "Y," "C," "M," and "B" representing each color may be omitted unless otherwise specified.

[0016] The image forming unit 20 includes a photosensitive drum (image carrier) 21 that is supported so as to be rotatable in a predetermined direction (clockwise in FIGS. 1 and 3). The image forming unit 20 further includes a charging unit 22, a developing device 40, and a drum cleaning unit 23 that are arranged around the photosensitive drum 21 along the direction of rotation of the photosensitive drum 21. 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 horizontally and has a photosensitive layer on its outer circumferential surface. The charging unit 22 charges the surface (outer circumferential surface) of the photosensitive drum 21 to a predetermined potential. The exposure unit 5 exposes the outer circumferential surface of the photosensitive drum 21 charged by the charging unit 22 to light, forming an electrostatic latent image of the original image on the outer circumferential surface of the photosensitive drum 21. The developing device 40 supplies toner to this electrostatic latent image to develop it into 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 toner and other substances remaining on the outer circumferential surface of the photosensitive drum 21 after the toner image has been primarily transferred to the outer circumferential surface of the intermediate transfer belt 31. In this way, the image forming unit 20 forms an image (toner image) that will later be transferred to paper S.

[0018] The transfer unit 30 includes an intermediate transfer belt 31, primary transfer units 32Y, 32C, 32M, and 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 supported so as to be rotatable in a predetermined direction (counterclockwise in FIG. 1), and is an endless intermediate transfer body onto 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 disposed in a so-called tandem arrangement, lined up in a row from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 31.

[0019] Primary transfer units 32Y, 32C, 32M, and 32B are disposed above image forming units 20Y, 20C, 20M, and 20B of the respective colors, with intermediate transfer belt 31 sandwiched between them. Secondary transfer unit 33 is disposed upstream of fixing unit 6 in the paper conveying direction of paper conveying unit 4, and downstream of four image forming units 20Y, 20C, 20M, and 20B in the rotation direction of intermediate transfer belt 31. Belt cleaning unit 34 is disposed downstream of secondary transfer unit 33 in the rotation direction of intermediate transfer belt 31.

[0020] The primary transfer unit 32 transfers the toner image formed on the outer circumferential surface of the photosensitive drum 21 onto the intermediate transfer belt 31. In other words, the toner image is primarily transferred onto the outer circumferential 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 successively transferred onto the intermediate transfer belt 31 in a superimposed manner at a predetermined timing, thereby forming a color toner image on the outer circumferential surface of the intermediate transfer belt 31 in which the toner images of the four colors of yellow, cyan, magenta, and black are superimposed.

[0021] The color toner image on the outer circumferential surface of intermediate transfer belt 31 is transferred to paper S, which has been synchronously fed by paper transport unit 4, at a secondary transfer nip formed in secondary transfer unit 33. Belt cleaning unit 34 removes and cleans toner and other adhering matter remaining on the outer circumferential surface of intermediate transfer belt 31 after secondary transfer. In this way, transfer unit 30 transfers (records) the toner image formed on the outer circumferential surface of photosensitive drum 21 onto paper S.

[0022] The fixing unit 6 is disposed above the secondary transfer unit 33. The fixing unit 6 fixes the toner image to the paper S by applying heat and pressure to the paper S onto which the toner image has been transferred.

[0023] The paper discharge section 7 is disposed above the transfer section 30. The paper S on which the toner image has been fixed and printing has been completed is transported to the paper discharge section 7. The paper discharge section 7 takes out the printed paper (printed matter) from the top.

[0024] The control unit 8 includes a CPU, an image processing unit, a memory unit, and other electronic circuits and electronic components (none of which are shown). The CPU controls the operation of each component provided in the image forming apparatus 1 based on control programs and data stored in the memory unit to perform processing related to the functions of the image forming apparatus 1. The paper supply unit 3, paper transport unit 4, exposure unit 5, image forming unit 20, transfer unit 30, and fixing unit 6 each receive individual commands from the control unit 8 and work together to print on the paper S. The memory unit is configured by a combination of a non-volatile storage device such as a program ROM (Read Only Memory) or a data ROM, and a volatile storage device such as a RAM (Random Access Memory).

[0025] Next, the configuration of the developing device 40 and its surroundings will be described with reference to Figure 3. Since the developing devices 40 for each color have the same basic configuration, the identification symbols representing each color and their descriptions 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 agitating and transporting member 42, a second agitating and transporting member 43, a developing roller 44, a regulating member 45, and a toner concentration sensor (development toner amount 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 in FIG. 3 ), and is disposed with its longitudinal direction horizontal. The developing container 41 contains a two-component developer containing toner and a magnetic carrier as the developer containing toner to be supplied to the photosensitive drum 21. The developing container 41 has a partition section 411, a first transport chamber 412, and a second transport chamber 413.

[0028] The partition 411 is provided in the lower part of the inside of the developing container 41. The partition 411 is disposed in the approximate center of the lower part of the developing container 41 in a direction intersecting the axial direction (the left-right lateral direction in FIG. 3 ), and extends in the axial direction and the up-down direction. The partition 411 divides the inside of the developing container 41 in the direction intersecting the axial direction (the left-right direction in FIG. 3 ). The developing container 41 is provided with communication parts (not shown) between the first transport chamber 412 and the second transport chamber 413 on both ends of the partition 411 in the axial direction (the depth direction of the paper in FIG. 3 ).

[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 dividing the interior of the developing container 41 by a partition 411, and are arranged side by side. The second transport chamber 413 is arranged inside the developing container 41 below and adjacent to the area where the developing roller 44 is arranged. The first transport chamber 412 is arranged in an area inside the developing container 41 that is farther away from the developing roller 44 than the second transport chamber 413. The first transport chamber 412 is replenished with developer via a supply pipe connection part 412a shown in FIG. 3.

[0030] The first agitation and transport member 42 is disposed inside the first transport chamber 412. The second agitation and transport member 43 is disposed inside the second transport chamber 413. The second agitation and transport member 43 extends parallel to and close to the developing roller 44. The first agitation and transport member 42 and the second agitation and transport member 43 are supported by the developing container 41 so as to be rotatable about an axis extending parallel to the photosensitive drum 21. The first agitation and transport member 42 and the second agitation and transport member 43 rotate about their axes, thereby agitating and transporting the developer in opposite directions along the axial direction of the rotation.

[0031] By the rotation of the first agitating and conveying member 42 and the second agitating and conveying member 43, the developer circulates between the first conveying chamber 412 and the second conveying chamber 413 through the communication portions disposed at both ends of the partition portion 411 in the axial direction. In the first conveying chamber 412 and the second conveying chamber 413, the toner supplied from the outside is agitated and charged.

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

[0033] A portion of the outer circumferential surface of the developing roller 44 is exposed from the developing container 41, and the developing roller 44 faces and is close to the photosensitive drum 21. The developing roller 44 carries toner on its outer circumferential surface in the region facing the photosensitive drum 21 to be supplied to the outer circumferential surface of the photosensitive drum 21. The developing roller 44 causes the toner in the second transport chamber 413 to adhere to the electrostatic latent image on the outer circumferential surface of the photosensitive drum 21, thereby forming a toner image.

[0034] The regulating member 45 is disposed upstream in the rotation direction of the developing roller 44 in the opposing region between the developing roller 44 and the photosensitive drum 21. The regulating member 45 is disposed closely opposite the developing roller 44, with a predetermined gap between its tip and the outer circumferential surface of the developing roller 44. The regulating member 45 extends over the entire area in the axial direction of the developing roller 44 (the depth direction in the plane of the paper in FIG. 3). The regulating member 45 regulates the layer thickness of the developer (toner) carried on the outer circumferential surface of the developing roller 44 that passes through the gap between the tip of the regulating member 45 and the outer circumferential surface of the developing roller 44.

[0035] The toner concentration sensor 46 is disposed on a wall portion along the longitudinal direction of the first transport chamber 412. The toner concentration sensor 46 is disposed opposite the first stirring and transport member 42. In this embodiment, a headless sensor is used as the toner concentration sensor 46. The detection surface of the toner concentration sensor 46, which is a headless sensor, is embedded in the inner wall surface of the first transport chamber 412. The toner concentration sensor 46 detects the toner concentration in the developer.

[0036] More specifically, the toner concentration sensor 46 is a magnetic permeability detection sensor that obtains the toner concentration (the mixture 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 in the first transport chamber 412 changes, the magnetic permeability also changes, and the output signal of the toner concentration sensor 46 also changes accordingly.

[0037] Regarding toner transport using multiple toner supply paths (described later), the control unit 8 controls the start and stop of supply of developer (toner and carrier) to the developing device 40 based on the sensor output signal received from the toner concentration sensor 46. In other words, the toner concentration sensor 46 is a developing toner amount detection unit that detects the amount of toner by detecting the toner concentration in the developing device 40, and is also a toner transport detection unit that detects toner transport errors.

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

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

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

[0041] Next, the configurations of the container 50 and the toner supply device 60 will be described with reference to Figs. 4 to 9. Fig. 4 is a perspective view of the periphery of the toner supply device 60 of the image forming apparatus 1 of Fig. 1. Figs. 5 and 6 are a front view and a side view of the periphery of the toner supply device 60 of Fig. 4. Figs. 7 and 8 are a perspective view and a plan view of the toner supply device 60 of Fig. 4. Fig. 9 is a perspective view of the first conveying pipe 65 and the second conveying pipe 66 of the toner supply device 60 of Fig. 7.

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

[0043] The first container 51 is disposed above the second container 52. The second container 52 is disposed below the first container 51. When viewed from the front, the first container 51 and the second container 52 are disposed offset from each other in the arrangement direction of the image forming unit 20 and the toner supply device 60. The first container 51 and the second container 52 are detachable from the main body 2, and store toner to be replenished to the developing device 40.

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

[0045] The first container 51 and the second container 52 are closed at one end (front side) in the axial direction Dx and have an opening (not shown) at the other end (rear side). The first container 51 and the second container 52 are connected to a first container connection part 61 and a second container connection part 62 of the toner supply device 60 at the open rear 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 by a drive unit (not shown) of the toner supply device 60 around an axis extending parallel to the axial direction Dx of the photosensitive drum 21. When the first container 51 and the second container 52 rotate, the toner inside them is sent toward the rear, which is the opening side, by the spiral protrusions 51s, 52s. As a result, the toner inside 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 arranged 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 transport the toner in the first container 51 and the second container 52 to the developing device 40 and supply it.

[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 conveying pipe 65, a second conveying pipe 66, a first conveying member 67, a second conveying member 68, a confluence portion 69, a conveying drive portion 70, an intermediate toner amount detection portion 71, and a rotation detection portion 80.

[0049] The toner supply device 60 has multiple toner supply paths that transport and replenish the toner in the container 50 to the developing device 40. Specifically, the toner supply device 60 includes a first toner supply path R1 that transports the toner from the first container 51 toward the developing device 40, and a second toner supply path R2 that transports the toner from the second container 52 toward the developing device 40. The first toner supply path R1 includes a first container connection portion 61, a first vertical pipe 63, a first transport pipe 65, and a first transport member 67. The second toner supply path R2 includes a second container connection portion 62, a second vertical pipe 64, a second transport pipe 66, and a second transport member 68.

[0050] The first container connection part 61 is located at the top of the toner supply device 60, and is higher than the second container connection part 62. The first container connection part 61 has a toner flow passage (not shown) therein. The opening side of the first container 51 is connected to the first container connection part 61, and rotatably supports the first container 51. The downstream end of the first container connection part 61 in the toner flow direction is connected to the first vertical pipe 63. When 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 part 61, passes through the first container connection part 61, and flows out toward the first vertical pipe 63.

[0051] The second container connection part 62 is located at the top of the toner supply device 60, below the first container connection part 61. The second container connection part 62 has a toner flow passage (not shown) therein. The opening side of the second container 52 is connected to the second container connection part 62, and rotatably supports the second container 52. The downstream end of the second container connection part 62 in the toner flow direction is connected to the second vertical pipe 64. When 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 part 62, passes through the second container connection part 62, and flows out toward the second vertical pipe 64.

[0052] The first vertical pipe 63 is disposed between the first container connection portion 61 and the first conveying 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 conveying pipe 65. When the toner in the first container 51 is replenished to the developing device 40, the toner flows from the first container connection portion 61 into the first vertical pipe 63, passes through the first vertical pipe 63, and flows out toward the first conveying pipe 65.

[0053] The second vertical pipe 64 is disposed between the second container connection portion 62 and the second conveying 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 conveying pipe 66. When the toner in the second container 52 is replenished to the developing device 40, the toner flows from the second container connection portion 62 into the second vertical pipe 64, passes through the second vertical pipe 64, and flows out toward the second conveying pipe 66.

[0054] Because the first container 51 and the first container connection part 61 are disposed higher than the second container 52 and the second container connection part 62, the first vertical pipe 63 is longer in the up-down direction than the second vertical pipe 64. Because the second container 52 and the second container connection part 62 are disposed lower than the first container 51 and the first container connection part 61, the second vertical pipe 64 is shorter in the up-down 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 arranged side by side on a straight line perpendicular to the axial direction Dx.

[0055] The first conveying pipe 65 is disposed between the first vertical pipe 63 and the junction 69 in the up-down direction. The first conveying pipe 65 is formed in a cylindrical shape extending horizontally. The first vertical pipe 63 is connected to one end of the first conveying pipe 65 in the extension direction. The other end of the first conveying pipe 65 in the extension direction is connected to the junction 69. When toner in the first container 51 is replenished to the developing device 40, the toner flows from the first vertical pipe 63 into the first conveying pipe 65 and passes through the first conveying pipe 65 to flow toward the junction 69. In other words, the first conveying pipe 65 is connected between the first container 51 and the junction 69, and the toner is conveyed from the first container 51 side toward the junction 69 side.

[0056] The second conveying pipe 66 is disposed between the second vertical pipe 64 and the junction 69 in the up-down direction. The second conveying pipe 66 is formed in a cylindrical shape extending horizontally. The second vertical pipe 64 is connected to one end of the second conveying pipe 66 in the extension direction. The other end of the second conveying pipe 66 in the extension direction is connected to the junction 69. When toner in the second container 52 is replenished to the developing device 40, the toner flows from the second vertical pipe 64 into the second conveying pipe 66 and passes through the second conveying pipe 66 to flow toward the junction 69. In other words, the second conveying pipe 66 is connected between the second container 52 and the junction 69, and the toner is conveyed from the second container 52 side toward the junction 69 side.

[0057] The first conveying pipe 65 and the second conveying pipe 66 are arranged in a direction (horizontal direction) intersecting their respective extension directions so that they join at a joining point 69 where the supply pipe 69a is connected. In other words, the first conveying pipe 65 and the second conveying pipe 66 are arranged so that their extension lines intersect on the joining point 69 side of their respective extension directions. The angle between the respective extension directions of the first conveying pipe 65 and the second conveying pipe 66 is an acute angle in the horizontal direction, and they are arranged in a V shape when viewed from above and below.

[0058] The first conveying member 67 is disposed within the first conveying pipe 65. The first conveying member 67 has a rotating shaft provided between both axial ends of the cylindrical first conveying pipe 65, and a first conveying blade formed on the outer circumferential surface of the rotating shaft and extending spirally along the axial direction. The first conveying member 67 is supported within the first conveying pipe 65 so as to be rotatable about an axis extending horizontally. One axial end of the first conveying member 67 is located within the confluence 69.

[0059] The first conveying member 67 rotates about its axis to convey the toner in the first conveying pipe 65 while stirring it in a toner conveying direction f1 (see FIGS. 8 and 9) parallel to the rotation axis. The first conveying member 67 conveys the toner in the first conveying pipe 65 from the first vertical pipe 63 side toward the junction 69 side. In other words, the first conveying member 67 conveys the toner from the first container 51 side toward the junction 69 side.

[0060] The second conveying member 68 is disposed within the second conveying pipe 66. The second conveying member 68 has a rotating shaft provided between both axial ends of the cylindrical second conveying pipe 66, and a second conveying blade formed on the outer circumferential surface of the rotating shaft and extending spirally along the axial direction. The second conveying member 68 is supported within the second conveying pipe 66 so as to be rotatable about an axis extending horizontally. One axial end of the second conveying member 68 is located within the confluence 69.

[0061] The second conveying member 68 rotates about its axis to convey the toner in the second conveying pipe 66 while stirring it in a toner conveying direction f2 (see FIGS. 8 and 9) parallel to the rotation axis. The second conveying member 68 conveys the toner in the second conveying pipe 66 from the second vertical pipe 64 side toward the junction 69 side. In other words, the second conveying member 68 conveys the toner from the second container 52 side toward the junction 69 side.

[0062] As described above, the first conveying pipe 65 and the second conveying pipe 66 are arranged in a V-shape when viewed from the top-bottom 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 shaft angle α.

[0063] The confluence 69 is disposed at the downstream end in the toner transport direction of each of the first transport pipe 65 and the second transport pipe 66. The confluence 69 merges the toner flows from the first transport pipe 65 and the second transport pipe 66 at the downstream end in the toner transport direction of the first transport pipe 65 and the second transport pipe 66. The confluence 69 also causes the merged toner flows into the developing device 40. The confluence 69 has a supply pipe 69a.

[0064] The supply pipe 69a is disposed below the junction 69, at the bottom of the toner supply device 60. The toner supply device 60 includes a single supply pipe 69a. The supply pipe 69a is formed in a cylindrical shape extending in the vertical direction. The upper end of the supply pipe 69a is connected to the point where the first conveying pipe 65 and the second conveying pipe 66 join. The lower end of the supply pipe 69a is connected to the supply pipe connection portion 412a of the developing device 40. When the toner in the first container 51 and the second container 52 is replenished to the developing device 40, the toner flows into the supply pipe 69a at the junction 69, passes through the supply pipe 69a, and flows into the developing device 40.

[0065] That is, the confluence 69 is disposed at the downstream end of the first toner supply path R1 and the second toner supply path R2 in the toner transport direction, and causes the toner to converge and flow into the developing device 40.

[0066] The transport drive unit 70 is disposed at the rear of the toner supply device 60, upstream of the first transport pipe 65 and the second transport pipe 66 in the toner transport direction. The transport drive unit 70 includes a motor 70m and a gear group 70g made up of a plurality of gears. The motor 70m is connected to each of the first transport member 67 and the second transport member 68 via the gear group 70g. The transport drive unit 70 selectively rotates one of the first transport member 67 and the second transport member 68 by rotating the motor 70m in the forward direction and the reverse direction.

[0067] The intermediate toner amount detection unit 71 includes a first intermediate toner amount detection unit 71A and a second intermediate toner amount detection unit 71B. The first intermediate toner amount detection unit 71A is disposed at the bottom of the first vertical tube 63. The second intermediate toner amount detection unit 71B is disposed at the bottom of the second vertical tube 64. The first intermediate toner amount detection unit 71A and the second intermediate toner amount detection unit 71B are configured with a magnetic permeability detection sensor similar to the toner concentration sensor 46. The first intermediate toner amount detection unit 71A detects changes in the magnetic permeability of the two-component developer at the bottom of the first vertical tube 63 and outputs a detection signal. The second intermediate toner amount detection unit 71B detects changes in the magnetic permeability of the two-component developer at the bottom of the second vertical tube 64 and outputs a detection signal.

[0068] Regarding toner transport using multiple toner supply paths, controller 8 controls the start and stop of developer supply to developing device 40 based on sensor output signals received from first intermediate toner amount detector 71A and second intermediate toner amount detector 71B. That is, first intermediate toner amount detector 71A is a toner amount detector that detects the amount of toner on first toner supply path R1. Second intermediate toner amount detector 71B is a toner amount detector that detects the amount of toner on second toner supply path R2. Furthermore, first intermediate toner amount detector 71A and second intermediate toner amount detector 71B are toner transport detectors that detect toner transport errors.

[0069] The rotation detection unit 80 is disposed at the rear of the toner supply device 60, upstream in the toner transport direction from the transport drive unit 70. The rotation detection unit 80 includes a container toner amount detection unit 81 and a light shielding plate (not shown) that rotates individually together with each of the first transport member 67 and the second transport member 68.

[0070] The container toner amount detection unit 81 is, for example, a light transmission sensor that includes a light emitting unit and a light receiving unit and has an optical path from the light emitting unit to the light receiving unit. A light shielding plate moves into and out of the optical path of the light transmission sensor. The container toner amount detection unit 81 detects the rotation of the first conveying member 67 and the second conveying member 68 and outputs a detection signal.

[0071] The control unit 8 detects the 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 toner amount detection unit 81 regarding toner transport using multiple toner supply paths. In detail, the control unit 8 counts the number of rotations of the first transport member 67 and the second transport member 68 based on the output signal from the container toner amount detection unit 81, and detects the amount of toner in the first container 51 and the second container 52 based on the number of rotations. In other words, the container toner amount detection unit 81 is a toner transport detection unit that detects the amount of toner in the container 50, thereby detecting a transport error in toner transport using multiple toner supply paths.

[0072] When the toner transport detection units (toner concentration sensor 46, intermediate toner amount detection unit 71, and container toner amount detection unit 81) detect a toner transport error in the toner supply path currently in use, control unit 8 switches to another toner supply path to transport the toner. In other words, when control unit 8 detects a toner transport error in either the first toner supply path R1 or the second toner supply path R2 currently in use, control unit 8 switches to the other toner supply path to transport the toner.

[0073] According to the above configuration, a transport error in toner transport using multiple toner supply paths is detected, and even if a transport error occurs in one of the supply paths, the toner can be continued to be transported and supplied by switching to another supply path. Therefore, in the image forming apparatus 1, it is possible to prevent the supply of toner to the developing device 40 from being stopped, and to continue forming suitable images.

[0074] As described above, the toner transport detection unit is a toner amount detection unit that includes the toner concentration sensor 46, the intermediate toner amount detection unit 71, and the container toner amount detection unit 81. Based on the detection results of these three toner amount detection units, the control unit 8 detects toner transport errors in the toner supply path currently in use. This allows for detection of toner transport errors corresponding to the respective characteristics of the developing device 40, the toner supply device 60, and the container 50. In other words, it is possible to appropriately detect toner transport errors in the first toner supply path R1 and the second toner supply path R2. Therefore, in the image forming apparatus 1, it is possible to prevent the toner supply to the developing device 40 from being stopped, thereby enabling the image forming apparatus 1 to continue to form appropriate images.

[0075] Furthermore, toner supply device 60 includes first toner supply path R1, second toner supply path R2, and junction 69, as well as first intermediate toner amount detection unit 71A and second intermediate toner amount detection unit 71B. This allows image forming apparatus 1 to transport toner using two toner supply paths. Even if a transport error occurs in one of the two toner supply paths, image forming apparatus 1 can switch to the other toner supply path and continue transporting and supplying toner.

[0076] Next, a general flow of the process for detecting toner transport errors for multiple toner supply paths will be described. Fig. 10 is a flowchart showing an example of the general process for detecting toner transport errors for multiple toner supply paths. In this embodiment, the image forming apparatus 1 has two toner supply paths: a first toner supply path R1 and a second toner supply path R2.

[0077] When the image forming apparatus 1 starts operating ("START" in FIG. 10), the control unit 8 starts transporting and replenishing toner to the developing device 40 using the first toner supply path R1 (step S101). Note that if the first container 51 has previously been empty, the control unit 8 may start transporting and replenishing toner to the developing device 40 using the second toner supply path R2.

[0078] Next, the control unit 8 determines whether or not a transport error has been detected in toner transport using the first toner supply path R1 by the toner transport detection units (toner concentration sensor 46, first intermediate toner amount detection unit 71A, and container toner amount detection unit 81) (step S102). If a toner transport error has not been detected (No in step S102), the process returns to step S101, and toner transport and supply to the developing device 40 using the first toner supply path R1 continues.

[0079] If the toner transport detection unit detects a toner transport error in the first toner supply path R1 currently in use (Yes in step S102), the control unit 8 switches to the second toner supply path R2 to transport the toner (step S103).

[0080] Next, the control unit 8 determines whether or not a toner transport error has been detected in the toner transport using the second toner supply path R2 by the toner transport detection unit (step S104). If a toner transport error has not been detected (No in step S104), the process returns to step S103, and the toner transport and supply to the developing device 40 using the second toner supply path R2 continues.

[0081] If the toner transport detection unit detects a toner transport error in the second toner supply route R2 that is currently in use (Yes in step S402), the control unit 8 ends the process shown in FIG.

[0082] If the image forming apparatus 1 is equipped with n other toner supply paths, such as the third, fourth, fifth, ..., nth, the control unit 8 sequentially switches to another toner supply path each time it detects a toner transport error in the toner supply path currently in use. Also, in this embodiment, when a toner transport error is detected in the second toner supply path R2 currently in use, if the transport error in toner transport using the first toner supply path R1 has been resolved, the control unit 8 switches to the first toner supply path R1 to transport toner.

[0083] Next, a first processing example, which is a detailed flow of the process for detecting toner transport errors for multiple toner supply paths, will be described. Fig. 11 is a flowchart showing the first processing example for detecting toner transport errors for multiple toner supply paths. As in Fig. 10, in this embodiment, image forming apparatus 1 has two toner supply paths: a first toner supply path R1 and a second toner supply path R2.

[0084] When the image forming apparatus 1 starts operating ("START" in FIG. 11), the control unit 8 starts transporting and replenishing toner to the developing device 40 using the first toner replenishing path R1 (step S201).

[0085] Next, the control unit 8 determines whether the amount of toner on the first toner supply path R1 is less than a predetermined value using the first intermediate toner amount detection unit 71A (step S202). If the amount of toner on the first toner supply path R1 is greater than the predetermined value (No in step S202), that is, if a toner transport error has not been detected, the process returns to step S201, and the transport and supply of toner to the developing device 40 using the first toner supply path R1 continues.

[0086] If the amount of toner on the first toner supply path R1 is less than the predetermined value (Yes in step S202), the control unit 8 determines whether the amount of toner in the first container 51 is greater than the predetermined value using the container toner amount detection unit 81 (step S203). If the amount of toner in the first container 51 is less than the predetermined value (No in step S203), that is, if a toner transport error has not been detected, the process returns to step S201, and the transport and supply of toner to the developing device 40 using the first toner supply path R1 continues.

[0087] In addition, the process of detecting when the amount of toner in the first container 51 is close to empty or empty, and the process of dealing with such a situation, are performed by a different processing flow, different from the process of detecting toner transport errors and the process of dealing with such errors in this embodiment.

[0088] If the amount of toner in the first container 51 is greater than the predetermined value (Yes in step S203), that is, if a toner transport error is detected, the control unit 8 determines that a toner transport error has occurred in the first toner supply path R1 in use (step S204).Then, the control unit 8 displays a warning message such as "Toner transport error detected in first toner supply path" or "Perform maintenance" on the display unit 2d of the main body 2 (step S205).

[0089] Next, the control unit 8 switches to the second toner supply path R2 and conveys the toner (step S206). From step S206 to step S208, the control unit 8 performs the same processes as steps S201 to S204 for the second toner supply path R2.

[0090] Then, after determining that a transport error has occurred in the toner transport using the second toner supply path R2 (step S208), the control unit 8 displays a warning message such as "Toner transport error detected in the second toner supply path / device stopped" or "Perform maintenance" on the display unit 2d of the main body 2 (step S209). Subsequently, the control unit 8 ends the process shown in FIG. 11.

[0091] Next, a second processing example, which is a detailed flow of the process for detecting toner transport errors for multiple toner supply paths, will be described. Fig. 12 is a flowchart showing the second processing example for detecting toner transport errors for multiple toner supply paths. As in Fig. 10, in this embodiment, image forming apparatus 1 has two toner supply paths: a first toner supply path R1 and a second toner supply path R2.

[0092] When the image forming apparatus 1 starts operating ("START" in FIG. 12), the control unit 8 starts transporting and replenishing toner to the developing device 40 using the first toner replenishing path R1 (step S301).

[0093] Next, the control unit 8 determines whether the amount of toner in the developing device 40 is less than a predetermined value using the toner concentration sensor 46 (step S302). If the amount of toner in the developing device 40 is greater than the predetermined value (No in step S302), that is, if a toner transport error has not been detected, the process returns to step S301, and the transport and supply of toner to the developing device 40 using the first toner supply path R1 continues.

[0094] If the amount of toner in developing device 40 is less than the predetermined value (Yes in step S302), control unit 8 determines whether the amount of toner on first toner supply path R1 is greater than the predetermined value using first intermediate toner amount detection unit 71A (step S303). If the amount of toner on first toner supply path R1 is less than the predetermined value (No in step S303), that is, if a toner transport error has not been detected, the process returns to step S301, and toner transport and supply to developing device 40 using first toner supply path R1 continues.

[0095] If the amount of toner on the first toner supply path R1 is greater than the predetermined value (Yes in step S303), that is, if a toner transport error is detected, the control unit 8 determines that a toner transport error has occurred on the first toner supply path R1 in use (step S304).Then, the control unit 8 displays a warning message such as "Toner transport error detected on first toner supply path" or "Perform maintenance" on the display unit 2d of the main body 2 (step S305).

[0096] Next, the control unit 8 switches to the second toner supply path R2 and conveys the toner (step S306). From step S306 to step S308, the control unit 8 performs the same processes as steps S301 to S304 for the second toner supply path R2.

[0097] Then, after determining that a transport error has occurred in the toner transport using the second toner supply path R2 (step S308), the control unit 8 displays a warning message such as "Toner transport error detected in the second toner supply path / device stopped" or "Perform maintenance" on the display unit 2d of the main body 2 (step S309). Subsequently, the control unit 8 ends the process shown in FIG.

[0098] The above configuration makes it possible to appropriately detect and determine toner transport errors in the first toner supply path R1 and the second toner supply path R2. Therefore, in the image forming apparatus 1, it is possible to prevent the toner supply to the developing device 40 from being stopped, and it is possible to continue forming images appropriately. Furthermore, it is possible to notify the user of a toner transport error in the supply path in which a toner transport error has been detected. This allows the image forming apparatus 1 to prompt the user to quickly address the toner transport error.

[0099] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these, and various modifications can be made without departing from the spirit of the invention.

[0100] For example, in the above embodiment, the image forming apparatus 1 is a so-called tandem type image forming apparatus for color printing that forms images of multiple colors by sequentially overlapping them, but the image forming apparatus is not limited to this type. The image forming apparatus may be a non-tandem type image forming apparatus for color printing or a monochrome image forming apparatus. [Industrial Applicability]

[0101] The present invention can be used in an image forming apparatus. [Explanation of symbols]

[0102] 1. Image forming device 2d display 8 Control Unit 20 Image forming unit 21 Photosensitive drum (image carrier) 30 Transfer unit 31 Intermediate transfer belt 40 Developing device 41 Developer container 44 Developing roller 46 Toner density sensor (toner amount detection unit, toner transport detection unit) 50 containers 51 Container No. 1 52 Second Container 60 Toner supply device 69 Junction 70 Conveyor drive unit 71 Intermediate toner amount detection unit (toner amount detection unit, toner transport detection unit) 71A First intermediate toner amount detector 71B Second intermediate toner amount detection unit 80 Rotation detection unit 81 Container toner amount detection unit (toner amount detection unit, toner transport detection unit) R1 First toner supply path R2 Second toner supply path S paper

Claims

1. a developing device that supplies toner to an image carrier; a container for accommodating the toner to be replenished to the developing device; a toner supply device having a plurality of toner supply paths for transporting the toner in the container to the developing device; a toner transport detection unit that detects a transport error in toner transport using the plurality of toner supply paths; a control unit for controlling the operations of the developing device and the toner supply device; Equipped with The image forming apparatus is characterized in that, when the toner transport detection unit detects a toner transport error in the toner supply path currently in use, the control unit switches to another toner supply path to transport the toner.

2. the toner transport detection unit includes a toner amount detection unit that detects the amount of toner in the developing device, the container, and the plurality of toner supply paths; 2. The image forming apparatus according to claim 1, wherein the control unit detects the toner transport error in the toner supply path currently in use based on the detection result of the toner amount detection unit.

3. The toner amount detection unit an intermediate toner amount detection unit that detects the amount of toner on the toner supply path; a container toner amount detection unit that detects the amount of toner in the container; Including, 3. The image forming apparatus according to claim 2, wherein the control unit determines that a toner transport error has occurred when the intermediate toner amount detection unit detects that the toner amount is less than a predetermined value and the container toner amount detection unit detects that the toner amount is greater than a predetermined value.

4. The toner amount detection unit a developing toner amount detection unit that detects the toner amount by detecting the toner concentration in the developing device; an intermediate toner amount detection unit that detects the amount of toner on the toner supply path; Including, 3. The image forming apparatus according to claim 2, wherein the control unit determines that a toner transport error has occurred when the developing toner amount detection unit detects that the toner amount is less than a predetermined value and the intermediate toner amount detection unit detects that the toner amount is greater than a predetermined value.

5. the containers include a first container and a second container containing the toner of the same color; the toner supply device, a first toner supply path that transports the toner from the first container toward the developing device; a second toner supply path for transporting the toner from the second container toward the developing device; a confluence portion disposed at a downstream end of each of the first toner supply path and the second toner supply path in a toner transport direction, where the toner flows together and flows into the developing device; a first intermediate toner amount detection unit that detects the amount of toner on the first toner supply path; a second intermediate toner amount detection unit that detects the amount of toner on the second toner supply path; 3. The image forming apparatus according to claim 2, further comprising:

Images