Developing device, image forming apparatus, and developer detection method

Abstract

To provide a developing device, an image forming apparatus, and a developer detection method that can improve the accuracy of detecting the amount of stored developer.SOLUTION: An image forming apparatus comprises: a first conveying member 42 that is rotatably provided in a housing 41 and stirs and conveys toner and carrier in the housing 41; a toner sensor 46 that outputs an electric signal according to a magnetic permeability at a detection position P1 on a conveyance path through which the first conveying member 42 conveys the toner and carrier; an acquisition processing unit that acquires a specific value based on the electric signal output during a rotational period of the first conveying member 42; and a correction processing unit that, when the fluctuation range of the electric signal output during the rotational period is less than a threshold, corrects the specific value on the basis of the rotational speed of the first conveying member 42, and when the fluctuation range is equal to or more than the threshold, corrects the specific value on the basis of the rotational speed of the first conveying member 42 and the fluctuation range.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a developing device, an image forming apparatus, and a developer detection method. [Background technology]

[0002] An electrophotographic image forming apparatus includes a developing device that develops an electrostatic latent image formed on an image carrier such as a photosensitive drum. The developing device includes a container that contains a developer such as toner, and develops the electrostatic latent image using the developer contained in the container.

[0003] For example, the storage section of this type of developing device stores a two-component developer containing the developer, which is a non-magnetic material, and a carrier, which is a magnetic material. The storage section is also provided with a transport section and a sensor. The transport section is rotatably provided in the storage section, and agitates and transports the developer and the carrier. The sensor outputs an electric signal according to the magnetic permeability at a predetermined detection position on the transport path of the developer and the carrier by the transport section. The sensor is used to detect the amount of the developer stored in the storage section.

[0004] However, when the rotation speed of the transport unit increases, the amount of the carrier stirred up by the transport unit increases, and the density of the carrier at the detection position decreases. This causes the output of the sensor to change regardless of whether the amount of the developer stored in the storage unit changes. Therefore, in a configuration in which the rotation speed of the transport unit can be changed, the detection accuracy of the amount of the developer stored in the storage unit decreases. In response to this, there is known an image forming apparatus that corrects the output value of the sensor based on the rotation speed of the transport unit, focusing on the fact that there is a relationship between the rotation speed of the transport unit and the output value of the sensor that can be expressed by a linear equation (see Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-268034 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is a limit to the decrease in the density of the carrier at the detection position as the rotation speed of the transport unit increases. If this limit is exceeded, the density of the carrier at the detection position will hardly decrease even if the rotation speed of the transport unit increases. In other words, if the rotation speed of the transport unit exceeds the limit value, the relationship between the rotation speed of the transport unit and the output value of the sensor changes. In the above-mentioned image forming apparatus, this point is not taken into consideration, and therefore the amount of the developer contained cannot be detected with high accuracy.

[0007] An object of the present invention is to provide a developing device, an image forming apparatus, and a developer detection method that can improve the detection accuracy of the amount of developer contained. [Means for solving the problem]

[0008] A developing device according to one aspect of the present invention includes a container, a transport unit, a sensor, an acquisition processing unit, and a correction processing unit. The container stores a developer. The transport unit is rotatably provided in the container and stirs and transports the developer in the container. The sensor outputs an electric signal according to a magnetic permeability at a predetermined detection position of a transport path of the developer by the transport unit. The acquisition processing unit acquires a specific value based on the electric signal output during a rotation cycle of the transport unit. When a fluctuation range of the electric signal output during a rotation cycle of the transport unit is less than a predetermined threshold value, the correction processing unit corrects the specific value based on a rotation speed of the transport unit, and when the fluctuation range is equal to or greater than the threshold value, the correction processing unit corrects the specific value based on the rotation speed of the transport unit and the fluctuation range.

[0009] An image forming apparatus according to another aspect of the present invention includes the above-described developing device.

[0010] A developer detection method according to another aspect of the present invention is executed by a developing device including a container for containing developer, a transport section rotatably provided in the container for stirring and transporting the developer in the container, and a sensor for outputting an electric signal corresponding to magnetic permeability at a predetermined detection position of a transport path of the developer by the transport section, and includes the following acquisition step and correction step. In the acquisition step, a specific value based on the electric signal output during a rotation cycle of the transport section is acquired. In the correction step, if a fluctuation range of the electric signal output during a rotation cycle of the transport section is less than a predetermined threshold value, the specific value is corrected based on a rotation speed of the transport section, and if the fluctuation range is equal to or greater than the threshold value, the specific value is corrected based on the rotation speed of the transport section and the fluctuation range. Effect of the Invention

[0011] According to the present invention, it is possible to improve the accuracy of detecting the amount of developer contained. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a system configuration of the image forming apparatus according to the embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing a configuration of an image forming unit of the image forming apparatus according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the configuration of the developing unit of the image forming apparatus according to the embodiment of the present invention. [Diagram 5] FIG. 5 is a flowchart showing an example of a developer detection process executed in the image forming apparatus according to the embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing the relationship between the electrical signal output from the toner sensor and the rotation speed of the first conveying member in the image forming apparatus according to the embodiment of the present invention. [Figure 7]FIG. 7 is a diagram showing the transition of an electrical signal output from a toner sensor in the image forming apparatus according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing the transition of an electrical signal output from a toner sensor in the image forming apparatus according to the embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing the transition of an electrical signal output from a toner sensor in the image forming apparatus according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing the transition of an electrical signal output from a toner sensor in an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0014] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to Figures 1 and 2. Here, Figure 1 is a cross-sectional view showing the configuration of the image forming apparatus 100.

[0015] For ease of explanation, the vertical direction in the installed state (as shown in FIG. 1) in which image forming apparatus 100 can be used is defined as up-down direction D1. Also, the front-rear direction D2 is defined with the left side of image forming apparatus 100 shown in FIG. 1 as the front (front face). Also, the left-right direction D3 is defined with the front face of image forming apparatus 100 in the installed state as the reference.

[0016] The image forming apparatus 100 is a multifunction machine having multiple functions such as a scanning function for reading image data from an original, a printing function for forming an image based on the image data, a facsimile function, a copy function, etc. Note that the image forming apparatus 100 may be a printing device, a facsimile device, a copy machine, etc.

[0017] As shown in FIGS. 1 and 2, an image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, an operation display unit 5, a storage unit 6, and a control unit .

[0018] The ADF 1 transports documents to be read by the scanning function, and includes a document setting section, a plurality of transport rollers, a document holder, and a paper ejection section.

[0019] The image reading unit 2 realizes the scanning function. The image reading unit 2 includes a document table, a light source, a plurality of mirrors, an optical lens, and a CCD (Charge Coupled Device).

[0020] The image forming unit 3 realizes the printing function. Specifically, the image forming unit 3 forms a color or monochrome image on a sheet fed from the paper feed unit 4 by electrophotography.

[0021] The paper feed unit 4 supplies sheets to the image forming unit 3. The paper feed unit 4 includes a paper feed cassette, a manual feed tray, a sheet transport path, and a plurality of transport rollers.

[0022] The operation display unit 5 is a user interface of the image forming apparatus 100. The operation display unit 5 has a display unit such as a liquid crystal display that displays various information in response to control instructions from the control unit 7, and an operation unit such as operation keys or a touch panel that inputs various information to the control unit 7 in response to user operations.

[0023] The storage unit 6 is a non-volatile storage device. For example, the storage unit 6 is a storage device such as a non-volatile memory such as a flash memory or an EEPROM (registered trademark), a solid state drive (SSD), or a hard disk drive (HDD).

[0024] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 2, the control unit 7 includes a CPU 11, a ROM 12, and a RAM 13. The CPU 11 is a processor that executes various arithmetic processing. The ROM 12 is a non-volatile storage device in which information such as a control program for causing the CPU 11 to execute various processing is stored in advance. The RAM 13 is a volatile or non-volatile storage device used as a temporary storage memory (work area) for various processing executed by the CPU 11. In the control unit 7, the CPU 11 executes various control programs previously stored in the ROM 12. As a result, the image forming apparatus 100 is overall controlled by the control unit 7.

[0025] The control unit 7 may be configured with an electronic circuit such as an application specific integrated circuit (ASIC). The control unit 7 may be a control unit provided separately from a main control unit that performs overall control of the image forming apparatus 100.

[0026] [Configuration of image forming unit 3] Next, the configuration of the image forming section 3 will be described with reference to Figures 1 to 3. Here, Figure 3 is a cross-sectional view showing the configuration of the image forming unit 24.

[0027] 1, the image forming section 3 includes four image forming units 21 to 24, an optical scanning device 25, an intermediate transfer belt 26, a secondary transfer roller 27, a fixing device 28, and a paper discharge tray 29. The image forming section 3 also includes a first drive section 30 (see FIG. 2).

[0028] Image forming unit 21 is an electrophotographic image forming unit corresponding to Y (yellow), image forming unit 22 is a C (cyan), image forming unit 23 is a M (magenta), and image forming unit 24 is a K (black). As shown in Fig. 1, image forming units 21 to 24 are arranged side by side in the order of yellow, cyan, magenta, and black from the front side of image forming apparatus 100 along a front-rear direction D2 of image forming apparatus 100.

[0029] 3, the image forming unit 24 includes a photoconductor drum 31, a charging roller 32, a developing unit 33, a primary transfer roller 34, and a drum cleaning unit 35. Each of the image forming units 21 to 23 has the same configuration as the image forming unit 24.

[0030] The photoconductor drum 31 carries a toner image. The photoconductor drum 31 receives a rotational driving force supplied from the first driving unit 30 and rotates in a rotational direction D4 shown in FIG.

[0031] The charging roller 32 charges the surface of the photoconductor drum 31. The surface of the photoconductor drum 31 charged by the charging roller 32 is irradiated with light based on image data emitted from the optical scanning device 25. As a result, an electrostatic latent image is formed on the surface of the photoconductor drum 31.

[0032] The developing unit 33 uses non-magnetic toner to develop the electrostatic latent image formed on the surface of the photoconductor drum 31. The toner is an example of the developer of the present invention. As a result, a toner image is formed on the surface of the photoconductor drum 31.

[0033] The primary transfer roller 34 transfers the toner image formed on the surface of the photoconductor drum 31 by the developing unit 33 onto the intermediate transfer belt 26 .

[0034] The drum cleaning unit 35 removes the toner remaining on the surface of the photosensitive drum 31 after the toner image has been transferred by the primary transfer roller 34 .

[0035] The optical scanning device 25 emits light based on image data toward the surfaces of the photoconductor drums 31 of the image forming units 21-24.

[0036] The intermediate transfer belt 26 is an endless belt member onto which the toner images formed on the surfaces of the photoconductor drums 31 of the image forming units 21 to 24 are transferred. The intermediate transfer belt 26 is stretched with a predetermined tension by a drive roller and a tension roller. The intermediate transfer belt 26 rotates in a rotation direction D5 shown in FIG. 3 as the drive roller rotates upon receiving a rotational driving force supplied from the first drive unit 30.

[0037] The secondary transfer roller 27 transfers the toner image transferred onto the surface of the intermediate transfer belt 26 onto a sheet supplied from the paper feed unit 4 .

[0038] The fixing device 28 fixes the toner image transferred onto the sheet by the secondary transfer roller 27 onto the sheet.

[0039] The sheet on which the toner image has been fixed by the fixing device 28 is discharged onto the paper discharge tray 29.

[0040] The first driving section 30 is a motor that supplies rotational driving force to the photoconductor drums 31 and developing sections 33 of the image forming units 21 to 24, the intermediate transfer belt 26, and the like.

[0041] [Configuration of Development Unit 33] Next, the configuration of the developing section 33 of the image forming unit 24 will be described with reference to Fig. 3 and Fig. 4. Here, Fig. 4 is a view of the first transport path 52 and the second transport path 53 of the housing 41 as seen from above. Note that the image forming units 21 to 23 also have the same configuration as the developing section 33 described below.

[0042] 3 and 4, the developing unit 33 includes a housing 41, a first transport member 42, a second transport member 43, a developing roller 44, a regulating member 45, and a toner sensor 46. The developing unit 33 also includes a toner container 47 (see FIG. 1) and a second driving unit 48 (see FIG. 2). Note that FIG. 2 shows the toner sensor 46 and the second driving unit 48 corresponding to the image forming unit 24.

[0043] The housing 41 houses a first transport member 42, a second transport member 43, a developing roller 44, and a regulating member 45. The housing 41 also houses a two-component developer containing the toner and a magnetic carrier. The housing 41 is an example of a storage section of the present invention. The housing 41 is formed long in the left-right direction D3. The housing 41 houses the toner and the carrier in an internal space formed by a bottom surface 51 (see FIG. 3) and a side wall.

[0044] 3 and 4, the housing 41 has a first transport path 52 and a second transport path 53 along which the toner and the carrier are transported. Specifically, a partition wall 54 (see FIG. 4) extending in the left-right direction D3 is provided on the bottom surface 51 of the housing 41. The first transport path 52 and the second transport path 53 extending in the left-right direction D3 are formed by the bottom surface 51, the side walls, and the partition wall 54 of the housing 41.

[0045] The first transport member 42 is rotatably provided in the housing 41. As shown in FIG. 4, the first transport member 42 is provided in the first transport path 52. The first transport member 42 transports the toner and the carrier contained in the first transport path 52 in a transport direction D6 shown in FIG. 4. The first transport member 42 stirs the toner and the carrier to frictionally charge the toner and the carrier. The first transport member 42 is an example of a transport unit of the present invention. For example, the first transport member 42 is a screw-shaped member that is rotatably provided around a rotation axis along the left-right direction D3 in the first transport path 52. The first transport member 42 rotates by receiving a rotation driving force supplied from the first drive unit 30. The first transport member 42 is not limited to a screw-shaped member, and may be any member that can stir and transport the toner and the carrier.

[0046] The second transport member 43 is rotatably provided in the housing 41. As shown in FIG. 4, the second transport member 43 is provided in the second transport path 53. The second transport member 43 transports the toner and the carrier contained in the second transport path 53 in a transport direction D7 shown in FIG. 4. The second transport member 43 stirs the toner and the carrier to frictionally charge the toner and the carrier. For example, the second transport member 43 is a screw-shaped member rotatably provided around a rotation axis along the left-right direction D3 in the second transport path 53. The second transport member 43 rotates by receiving a rotational driving force supplied from the first drive unit 30.

[0047] A first passage 55 leading to the second conveying path 53 is provided at the downstream end of the first conveying path 52 in the conveying direction D6. The first passage 55 is formed by the side wall of the housing 41 and the right end of the partition wall 54. A second passage 56 leading to the first conveying path 52 is provided at the downstream end of the second conveying path 53 in the conveying direction D7. The second passage 56 is formed by the side wall of the housing 41 and the left end of the partition wall 54. In other words, inside the housing 41, the first conveying path 52, the first passage 55, the second conveying path 53, and the second passage 56 form a circulating conveying path through which the toner and the carrier circulate.

[0048] The developing roller 44 develops the electrostatic latent image formed on the photosensitive drum 31 using the toner. As shown in FIG. 3, the developing roller 44 is provided facing the second transport member 43 and the photosensitive drum 31. The developing roller 44 is rotatably supported by the housing 41, and rotates in a rotation direction D8 (see FIG. 3) by receiving a rotational driving force supplied from the first driving unit 30. The developing roller 44 scoops up the toner and the carrier from the second transport path 53. The toner and the carrier scooped up by the developing roller 44 form a magnetic brush on the outer circumferential surface of the developing roller 44 by the magnetic force of a magnetic pole provided inside the developing roller 44. The developing roller 44 transports the magnetic brush formed on the outer circumferential surface to an opposing region R1 (see FIG. 3) with the photosensitive drum 31, and moves the toner contained in the magnetic brush to the surface of the photosensitive drum 31. As a result, the electrostatic latent image formed on the photosensitive drum 31 is developed.

[0049] 3, the regulating member 45 is provided downstream in the rotation direction D8 of the opposing region between the second transport member 43 and the developing roller 44, and upstream in the rotation direction D8 of the opposing region R1 between the developing roller 44 and the photoconductor drum 31. The regulating member 45 is provided opposite the outer circumferential surface of the developing roller 44 so that a predetermined gap is formed between the regulating member 45 and the outer circumferential surface of the developing roller 44.

[0050] The toner sensor 46 outputs an electric signal according to the magnetic permeability at a detection position P1 (see FIG. 4) of the transport path of the toner and the carrier by the first transport member 42. The toner sensor 46 is an example of a sensor of the present invention. As shown in FIG. 3, the toner sensor 46 is provided on the bottom surface of the housing 41. For example, the toner sensor 46 outputs a voltage according to the magnetic permeability at the detection position P1. For example, the voltage output by the toner sensor 46 decreases as the amount of the toner at the detection position P1 increases. The toner sensor 46 is used to detect the amount of the toner contained in the developing unit 33.

[0051] The toner container 47 contains the K (black) toner. The toner container 47 includes a container body, a supply port, and a conveying member 47A (see FIG. 1). The container body is formed long in the left-right direction D3, and contains the toner therein. The supply port is formed at the left end of the container body. The supply port opens downward. The supply port communicates with an opening 57 (see FIG. 3) formed in the upper surface of the housing 41 via a supply path (not shown) that extends vertically.

[0052] The opening 57 opens toward a supply position P2 (see FIG. 4) on the upstream side of the transport path of the toner and the carrier by the first transport member 42 relative to a detection position P1 on the transport path. As shown in FIG. 4, the supply position P2 is a position at the left end of the first transport path 52.

[0053] The transport member 47A supplies the toner from the toner container 47 to a supply position P2 (see FIG. 4) in the housing 41. The transport member 47A is provided rotatably around a rotation axis along the left-right direction D3 in the toner container 47, and transports the toner to the supply port portion in an amount corresponding to the number of rotations. For example, the transport member 47A is a screw-shaped member capable of transporting the toner in the toner container 47 to the left. The toner transported to the supply port portion by the transport member 47A moves in the supply path by its own weight and falls to the supply position P2 in the housing 41. In other words, the transport member 47A can supply the toner to the supply position P2 in the housing 41 in an amount corresponding to the number of rotations.

[0054] The second driving unit 48 supplies a driving force to the transport member 47A. For example, the second driving unit 48 is a motor. The transport member 47A receives the rotational driving force supplied from the second driving unit 48 and rotates.

[0055] However, when the rotation speed of the first transport member 42 increases, the amount of the carrier stirred up by the first transport member 42 increases, and the density of the carrier at the detection position P1 decreases. As a result, the output of the toner sensor 46 changes regardless of whether the amount of toner stored in the housing 41 changes. Therefore, in a configuration in which the rotation speed of the first transport member 42 can be changed, the detection accuracy of the amount of toner stored in the housing 41 decreases. In response to this, there is known an image forming apparatus that corrects the output value of the toner sensor 46 based on the rotation speed of the first transport member 42, focusing on the fact that there is a relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46 that can be expressed by a linear equation.

[0056] However, there is a limit to the decrease in the carrier density at the detection position P1 associated with an increase in the rotation speed of the first transport member 42. When this limit is exceeded, the carrier density at the detection position P1 hardly decreases even if the rotation speed of the first transport member 42 increases. In other words, when the rotation speed of the first transport member 42 exceeds the limit value, the relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46 changes. In the above-mentioned image forming apparatus, this point is not taken into consideration, and therefore the amount of toner contained cannot be detected with high accuracy.

[0057] Fig. 6 shows an example of the relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46. In Fig. 6, the output value of the toner sensor 46 is plotted when the rotation speed of the first transport member 42 is a multiple of 100 rpm. Note that in Fig. 6, the output value of the toner sensor 46 is shown as an 8-bit digital value.

[0058] As shown in FIG. 6, when the rotation speed of the first transport member 42 is in the range of 100 rpm to 400 rpm, it is recognized that there is a relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46 that can be expressed by a linear equation. On the other hand, when the rotation speed of the first transport member 42 exceeds about 400 rpm, the relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46 changes. In this example, it is considered that the decrease in the carrier density reaches its limit when the rotation speed of the first transport member 42 exceeds about 400 rpm. The rotation speed of the first transport member 42 at which the decrease in the carrier density reaches its limit (hereinafter referred to as the "limit speed") varies depending on factors such as the temperature and humidity inside the housing 41 and the amount of toner contained in the housing 41.

[0059] In contrast, in the image forming apparatus 100 according to the embodiment of the present invention, it is possible to improve the accuracy of detecting the amount of toner contained in the housing 41, as will be described below.

[0060] Specifically, in the image forming apparatus 100, it is determined whether or not the rotation speed of the first conveying member 42 exceeds the limit speed based on the fluctuation width of the electrical signal of the toner sensor 46 output during the rotation cycle of the first conveying member 42. The fluctuation width is the difference between the maximum and minimum values ​​of the electrical signal of the toner sensor 46 output during the rotation cycle of the first conveying member 42. Then, depending on the result of the determination, a method of correcting the output value of the toner sensor 46 is switched.

[0061] 7 shows an example of the transition of the output value of the toner sensor 46 output during the rotation period T1 of the first conveying member 42 when the rotation speed of the first conveying member 42 is 300 rpm. FIG. 8 shows an example of the transition of the output value of the toner sensor 46 output during the rotation period T2 of the first conveying member 42 when the rotation speed of the first conveying member 42 is 400 rpm. FIG. 9 shows an example of the transition of the output value of the toner sensor 46 output during the rotation period T3 of the first conveying member 42 when the rotation speed of the first conveying member 42 is 500 rpm. FIG. 10 shows an example of the transition of the output value of the toner sensor 46 output during the rotation period T4 of the first conveying member 42 when the rotation speed of the first conveying member 42 is 600 rpm. In FIG. 6, the maximum value of the output value of the toner sensor 46 output during the rotation period of the first conveying member 42 when the rotation speed of the first conveying member 42 is a multiple of 100 rpm is plotted.

[0062] As shown in Figs. 6 to 8, when the rotation speed of the first conveying member 42 is equal to or lower than the limit speed, the fluctuation range does not change even if the rotation speed of the first conveying member 42 increases. On the other hand, as shown in Figs. 6, 9, and 10, when the rotation speed of the first conveying member 42 exceeds the limit speed, the fluctuation range increases in response to an increase in the rotation speed of the first conveying member 42. In other words, it is possible to determine whether the rotation speed of the first conveying member 42 exceeds the limit speed based on the fluctuation range. In addition, it is possible to determine the difference between the rotation speed of the first conveying member 42 and the limit speed when the rotation speed of the first conveying member 42 exceeds the limit speed based on the change range.

[0063] [Configuration of control unit 7] Hereinafter, the control unit 7 that corrects the output value of the toner sensor 46 will be described with reference to FIG.

[0064] 2, the control unit 7 includes a drive control unit 61, an acquisition processing unit 62, a correction processing unit 63, and an output processing unit 64. An apparatus including the developing unit 33, the acquisition processing unit 62, the correction processing unit 63, and the output processing unit 64 is an example of the developing device of the present invention.

[0065] Specifically, a developer detection program for causing the CPU 11 of the control unit 7 to execute a developer detection process (see the flowchart in FIG. 5) described later is stored in advance in the ROM 12 of the control unit 7. The CPU 11 of the control unit 7 executes the developer detection program stored in the ROM 12, thereby functioning as a drive control unit 61, an acquisition processing unit 62, a correction processing unit 63, and an output processing unit 64.

[0066] The developer detection program may be recorded on a computer-readable recording medium such as a CD, a DVD, or a flash memory, and may be read from the recording medium and stored in a storage device such as the storage unit 6. The drive control unit 61, the acquisition processing unit 62, the correction processing unit 63, and the output processing unit 64 may be configured by electronic circuits.

[0067] In the following, of the image forming units 21 to 24, the components included in the image forming unit 24 will be described as an example. The following description also applies to each of the image forming units 21 to 23 in the same manner.

[0068] When a print process is executed in which an image is formed on a sheet using the image forming unit 3, the drive control unit 61 drives the first drive unit 30 at a predetermined specific drive speed.

[0069] Here, the specific driving speed is a driving speed of the first driving unit 30 corresponding to a specific printing speed set by a user operation as an execution speed of the printing process among a plurality of predetermined printing speeds. That is, in the image forming apparatus 100, the first driving unit 30 is driven at any one of a plurality of driving speeds corresponding to the plurality of printing speeds. Also, the first conveying member 42 is rotated at any one of a plurality of rotation speeds corresponding to the driving speeds of the plurality of first driving units 30. For example, the first conveying member 42 is rotated at any one of the rotation speeds of 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, and 600 rpm (see FIG. 6).

[0070] The acquisition processing unit 62 acquires a specific value based on the electrical signal of the toner sensor 46 output during the rotation period of the first conveying member 42.

[0071] Here, the specific value is the maximum value of the electrical signal output from the toner sensor 46 during the rotation period of the first conveying member 42.

[0072] The specific value may be a minimum value of the electrical signal output from the toner sensor 46 during a rotation period of the first conveying member 42. Alternatively, the specific value may be an average value of the electrical signal output from the toner sensor 46 during a rotation period of the first conveying member 42.

[0073] The correction processing unit 63 executes a predetermined first correction process when the fluctuation range of the electrical signal of the toner sensor 46 output during the rotation period of the first conveying member 42 is less than a predetermined threshold. Specifically, the first correction process is a process of correcting the specific value based on the rotation speed of the first conveying member 42.

[0074] Furthermore, when the fluctuation range is equal to or greater than the threshold value, the correction processing unit 63 executes a second correction process that is different from the first correction process. Specifically, the second correction process is a process for correcting the specific value based on the rotation speed of the first conveying member 42 and the fluctuation range.

[0075] Here, the threshold value is determined based on the fluctuation width when the rotation speed of the first conveying member 42 is equal to or lower than the limit speed. For example, the threshold value is a value obtained by multiplying the fluctuation width when the rotation speed of the first conveying member 42 is equal to or lower than the limit speed by a predetermined coefficient such as 1.2. The threshold value may be set in advance, for example, when the image forming apparatus 100 is shipped. The threshold value may also be set each time a predetermined setting timing arrives. For example, the control unit 7 may set the threshold value based on the fluctuation width of the electrical signal of the toner sensor 46 acquired when the first conveying member 42 is rotated at the slowest rotation speed. The setting timing may be the timing when the power of the image forming apparatus 100 is turned on, the timing when the cumulative number of printed sheets in the image forming apparatus 100 reaches a multiple of a predetermined reference number, or the like.

[0076] For example, in the first correction process, the specific value is corrected based on the following formula (1). The reference speed included in formula (1) is a rotation speed at which correction of the output value of the toner sensor 46 is not required, among the multiple rotation speeds of the first transport member 42 corresponding to the multiple printing speeds. The first correction coefficient included in formula (1) is a value that is determined in advance based on the relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46 shown in FIG. 6. Specifically, the first correction coefficient is a value that corresponds to the gradient of a linear approximation that expresses the relationship between the rotation speed of the first transport member 42 and the output value of the toner sensor 46 when the rotation speed of the first transport member 42 is equal to or lower than the limit speed (see FIG. 6).

[0077] Corrected specific value=pre-corrected specific value−(current rotation speed of the first conveying member 42−reference speed)×first correction coefficient (1)

[0078] In the second correction process, the specific value is corrected based on the following formula (2). The second correction coefficient included in formula (2) is a value that is determined in advance based on the relationship between the rotation speed of the first conveying member 42 and the output value of the toner sensor 46 shown in Fig. 6. The second correction process may be a process that corrects the specific value using a formula different from formula (2).

[0079] Corrected specific value=pre-correction specific value−(current rotation speed of first conveying member 42−reference speed)×first correction coefficient+(fluctuation range of electrical signal of toner sensor 46)×second correction coefficient (2)

[0080] The output processing unit 64 outputs the specific value corrected by the correction processing unit 63. The specific value after correction output by the output processing unit 64 is input to a processing entity inside the control unit 7 that executes processing based on the specific value. Note that, when a main control unit that performs overall control of the image forming apparatus 100 is provided separately from the control unit 7, the specific value after correction output by the output processing unit 64 may be input to the main control unit or stored in a register provided in the control unit 7.

[0081] For example, the corrected specific value output by the output processing unit 64 is used to control the supply of the toner to the developing unit 33 and to control the execution of the printing process. For example, in the image forming device 100, when the corrected specific value output by the output processing unit 64 is equal to or greater than a predetermined first reference value, the toner is supplied from the toner container 47 to the developing unit 33. Also, in the image forming device 100, when the corrected specific value output by the output processing unit 64 is equal to or greater than a second reference value higher than the first reference value, a toner empty state is detected and the execution of the printing process is restricted.

[0082] [Developer detection process] 5, a developer detection method of the present invention will be described together with an example of the procedure of the developer detection process executed by the control unit 7 in the image forming apparatus 100. Here, steps S11, S12, etc. indicate the numbers of the process procedures (steps) executed by the control unit 7. The developer detection process is executed when an instruction to execute the print process is input.

[0083] <Step S11> First, in step S11, the control unit 7 drives the first drive unit 30 at the specific drive speed. Here, the process of step S11 is executed by the drive control unit 61 of the control unit 7. As a result, the drive force of the first drive unit 30 is supplied to the developing unit 33, and the first transport member 42 is rotated at a rotation speed corresponding to the specific drive speed.

[0084] <Step S12> In step S12, the control unit 7 acquires the specific value based on the electrical signal of the toner sensor 46 output during the rotation period of the first conveying member 42. Here, the process of step S12 is an example of an acquisition step of the present invention, and is executed by the acquisition processing unit 62 of the control unit 7.

[0085] <Step S13> In step S13, the control unit 7 determines whether the fluctuation width of the electrical signal of the toner sensor 46 output during the rotation period of the first conveying member 42 is less than the threshold value.

[0086] Here, the control unit 7 switches the next process depending on the result of the determination of whether the fluctuation range is less than the threshold value. Specifically, when the control unit 7 determines that the fluctuation range is less than the threshold value (Yes side of step S13), it shifts the process to step S14. On the other hand, when the control unit 7 determines that the fluctuation range is equal to or greater than the threshold value (No side of step S13), it shifts the process to step S15.

[0087] <Step S14> In step S14, the control unit 7 executes the first correction process. The process in step S14 is an example of a correction step of the present invention, and is executed by the correction processing unit 63 of the control unit 7.

[0088] <Step S15> In step S15, the control unit 7 executes the second correction process. The process in step S15 is an example of a correction step of the present invention, and is executed by the correction processing unit 63 of the control unit 7.

[0089] <Step S16> In step S16, the control unit 7 outputs the specific value corrected in step S14 or step S15. The process of step S16 is executed by the output processing unit 64 of the control unit 7.

[0090] <Step S17> In step S17, the control unit 7 determines whether or not the printing process is completed.

[0091] Here, the control unit 7 switches to the next process depending on the result of the determination as to whether the printing process has been completed. Specifically, when the control unit 7 determines that the printing process has been completed (Yes side of step S17), it ends the developer detection process. On the other hand, when the control unit 7 determines that the printing process has not been completed (No side of step S17), it shifts the process to step S12. In this case, the control unit 7 repeatedly executes the processes from step S12 to step S16 until it is determined that the printing process has been completed. This makes it possible to accurately detect the amount of toner contained in the housing 41 even if the limit speed changes during the execution of the printing process due to changes in temperature and humidity inside the housing 41 and changes in the amount of toner contained in the housing 41.

[0092] In this way, in the image forming apparatus 100, it is determined whether or not the rotation speed of the first conveying member 42 exceeds the limit speed based on the fluctuation range of the electrical signal of the toner sensor 46 output during the rotation cycle of the first conveying member 42. Then, depending on the determination result, the correction method of the output value of the toner sensor 46 is switched. Specifically, when the fluctuation range is less than the threshold value, the specific value is corrected based on the rotation speed of the first conveying member 42. Also, when the fluctuation range is equal to or greater than the threshold value, the specific value is corrected based on the rotation speed of the first conveying member 42 and the fluctuation range. This makes it possible to improve the detection accuracy of the amount of toner stored in the housing 41 compared to a configuration in which the output value of the toner sensor 46 is corrected based on the rotation speed of the first conveying member 42 without determining whether or not the rotation speed of the first conveying member 42 exceeds the limit speed.

[0093] The housing 41 may contain a one-component developer that does not contain the carrier. In this case, the toner may be a magnetic material. [Explanation of symbols]

[0094] 1 ADF 2 Image reading section 3. Image forming section 4 Paper feed section 5 Operation display section 6 Memory section 7 Control section 24 Image forming unit 30 First Drive Unit 33 Development section 41 Case 42 First conveying member 46 Toner sensor 61 Drive control unit 62 Acquisition processing unit 63 Correction processing section 64 Output Processing Section 100 Image forming device

Claims

1. A container for containing a developer; a conveying section rotatably provided in the container section and configured to agitate and convey the developer in the container section; a sensor that outputs an electric signal according to magnetic permeability at a predetermined detection position on a transport path of the developer by the transport unit; an acquisition processing unit that acquires a specific value based on the electrical signal output during a rotation period of the transport unit; a correction processing unit that corrects the specific value based only on the rotation speed of the conveying unit out of the rotation speed of the conveying unit and the fluctuation range when a fluctuation range of the electrical signal output during a rotation cycle of the conveying unit is less than a predetermined threshold value, and corrects the specific value based on both the rotation speed of the conveying unit and the fluctuation range when the fluctuation range is equal to or greater than the threshold value; A developing device comprising:

2. The conveying unit is a screw-shaped member. The developing device according to claim 1 .

3. The developer is a non-magnetic toner, the container contains the toner and the magnetic carrier; 3. The developing device according to claim 1 or 2.

4. the specific value is a maximum value or a minimum value of the electrical signal output during a rotation period of the conveying unit; The developing device according to any one of claims 1 to 3.

5. 5. An image forming apparatus comprising the developing device according to claim 1.

6. A developer detection method executed in a developing device including: a container that contains a developer; a transport unit that is rotatably provided in the container and that stirs and transports the developer in the container; and a sensor that outputs an electric signal according to magnetic permeability at a predetermined detection position on a transport path of the developer by the transport unit, the method comprising: acquiring a specific value based on the electrical signal output during a rotation period of the transport unit; a correction step of correcting the specific value based only on the rotation speed of the conveying unit out of the rotation speed of the conveying unit and the fluctuation range when a fluctuation range of the electrical signal output during a rotation cycle of the conveying unit is less than a predetermined threshold, and correcting the specific value based on both the rotation speed of the conveying unit and the fluctuation range when the fluctuation range is equal to or greater than the threshold; A developer detection method comprising:

Images