Developing apparatus and image forming apparatus

Abstract

To correctly detect the concentration of toner with a permeability sensor even when a developing device removed from an image forming apparatus is installed and reused in another image forming apparatus.SOLUTION: An image forming apparatus has a control unit that can execute an initialization mode for, when a developing device is a new developing device storing an initial developer having a predetermined toner concentration, changing a control voltage to be applied to a permeability sensor and setting, to a setting storage unit of the developing device, a control voltage Vcnt1 in which an output voltage output from the permeability sensor is an output voltage according to the predetermined toner concentration in the initial developer. When the developing device is a developing device in which the initialization mode is executed by another image forming apparatus, the control unit resets the control voltage stored in the setting storage unit of the developing device on the basis of a variation value of the control voltage.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus including a developing device that develops an electrostatic latent image formed on an image carrier with a developer. [Background technology]

[0002] In image forming devices such as printers and copiers, two-component developing devices that perform development using a two-component developer containing a carrier and a toner, and one-component developing devices that perform development using a one-component developer containing only a toner are known.

[0003] A two-component developing device is usually equipped with a magnet roller made of a magnet body having multiple magnetic poles inside, and a cylindrical developer carrier supported for rotation. In a two-component developing device, a two-component developer containing a magnetic carrier with a toner attached thereto is carried on the developer carrier and transported to a development area facing an image carrier, where a magnetic brush is formed to supply the toner to the image carrier, thereby developing an electrostatic latent image. In such a two-component developing device, the toner is charged by stirring and mixing the magnetic carrier and the toner, so that the chargeability of the toner is stable, and a relatively stable and good image can be obtained.

[0004] However, in a two-component developing device, the toner concentration fluctuates based on the consumption of toner, and the mixture ratio of toner and magnetic carrier changes. Therefore, for example, a toner concentration control device is provided to replenish toner as needed.

[0005] A magnetic permeability sensor (also called an inductance sensor) is attached to the developing device in order to detect the toner concentration. The magnetic permeability sensor can output an output voltage according to the magnetic permeability of the developer when a voltage is applied. Hereinafter, the voltage applied to the magnetic permeability sensor is called a control voltage. The magnetic permeability sensors attached to the developing devices have individual differences in the "relationship between the control voltage and the output voltage" due to variations in each magnetic permeability sensor, variations in assembly into the developing device, variations in the control voltage applied to the magnetic permeability sensor, and the like. In other words, even if the same control voltage is applied to the magnetic permeability sensor when the toner concentration is the same, different output voltages are output from the magnetic permeability sensors attached to each developing device, and as a result, different toner concentrations are detected despite the same toner concentration. In other words, there is a risk that the toner concentration cannot be detected correctly.

[0006] Conventionally, when a new developing device is installed in an image forming apparatus and used, an initialization control process is performed to initialize the magnetic permeability sensor for toner concentration detection. In the initialization control process of the magnetic permeability sensor, a conveying screw or the like provided in the developing device is driven to distribute the developer throughout the developing device, and then a control voltage applied to the magnetic permeability sensor is changed and a corresponding output voltage is obtained from the magnetic permeability sensor. A new developing device contains a developer that has been adjusted to a target concentration before shipping from the factory. Therefore, in the initialization control process, the control voltage when the output voltage corresponding to the target concentration is obtained is set as the control voltage to be applied to the magnetic permeability sensor for proper toner concentration detection. In other words, when a new developing device is installed in an image forming apparatus and used, the initialization control process of the magnetic permeability sensor is performed, so that the toner concentration can be correctly detected. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2008-96763 A Summary of the Invention [Problem to be solved by the invention]

[0008] On the other hand, when a used developing device removed from an image forming device is reused by installing it in another image forming device, the presence or absence of developer and the toner concentration of the used developing device are unknown, so the above-mentioned initialization control process cannot be performed. Even if the above-mentioned initialization control process is performed, there is a risk that the toner concentration cannot be detected correctly.

[0009] Patent document 1 also discloses a technology for re-setting the control voltage according to the difference in linear speed of the main body before and after replacement, based on the control voltage setting value determined in the initialization control process, when a used developing device removed from an image forming device is installed in another image forming device and reused.

[0010] However, since the variation in the control voltage applied to the magnetic permeability sensor differs depending on the individual image forming apparatus, the set value of the control voltage determined in the initialization control process varies depending on the individual image forming apparatus. Therefore, in the technology disclosed in Patent Document 1, the toner concentration cannot be detected correctly due to the variation in the control voltage applied to the magnetic permeability sensor, and there is a risk of image defects such as fogged images occurring due to the toner concentration deviation.

[0011] An object of the present invention is to provide an image forming apparatus that can accurately detect toner concentration using a magnetic permeability sensor even when a developing device removed from the image forming apparatus is installed in another image forming apparatus and reused. [Means for solving the problem]

[0012] A representative configuration of the present invention for achieving the above object includes an image carrier, a developing device that develops an electrostatic latent image formed on the image carrier using a developer containing toner and a carrier, a replaceable storage container that stores replenishment developer to be replenished to the developing device, a magnetic permeability sensor that can output an output voltage corresponding to a toner concentration of the developer stored in the developing device by application of a preset control voltage, a power source that applies the control voltage to the magnetic permeability sensor, a main body storage unit that stores a variation value α2 of the control voltage applied by the power source to the magnetic permeability sensor that is measured in advance in a manufacturing process, a setting storage unit that is provided in the developing device and stores the preset control voltage, and the developing device is a new developing device that stores an initial developer having a predetermined toner concentration. and a control unit capable of executing an initialization mode in which a control voltage Vcnt1 is set in the setting memory unit to change a control voltage applied to the magnetic permeability sensor so that an output voltage output from the magnetic permeability sensor becomes an output voltage corresponding to the specified toner concentration of the initial developer when the developing device is a developing device that has had the initialization mode executed in another image forming device, the control unit calculates a control voltage Vcnt2 to be applied to the magnetic permeability sensor of the developing device that has had the initialization mode executed based on the control voltage Vcnt1 stored in the setting memory unit of the developing device that has had the initialization mode executed, a control voltage variation value α1, and a control voltage variation value α2 stored in the main body memory unit, using the following formula: Vcnt2=Vcnt1×(1+α1 / 100) / (1+α2 / 100) and resets the calculated control voltage Vcnt2 in the setting memory unit of the developing device that has had the initialization mode executed. Effect of the Invention

[0013] According to the present invention, even when a developing device removed from an image forming apparatus is reused by installing it in another image forming apparatus, the toner concentration can be detected correctly by the magnetic permeability sensor. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus. [Diagram 2] 1 is a schematic cross-sectional view showing an image forming unit of an image forming apparatus; [Diagram 3] FIG. 1 is a block diagram showing a system configuration for controlling an image forming apparatus. [Figure 4] Schematic cross-sectional view of a developing device [Diagram 5] Schematic top view of a developing device [Figure 6] Schematic diagram showing a replenishing device [Figure 7] Graph showing the relationship between the output voltage of the magnetic permeability sensor and the toner concentration [Figure 8] Flowchart of initialization control of developing device [Figure 9] FIG. 1 is a block diagram showing a system configuration of a toner supply control system for an image forming apparatus; [Figure 10] Graph showing the inherent sensitivity characteristics of magnetic permeability sensors [Figure 11] Table showing the control voltage to the permeability sensor [Figure 12] Flowchart of control voltage correction to the magnetic permeability sensor of the first embodiment [Figure 13] FIG. 13 is a table showing the control voltage correction results for the magnetic permeability sensor of Example 1. [Figure 14] Graph showing power supply voltage characteristics to the magnetic permeability sensor of the sensor power supply / control unit of Example 2 [Figure 15] Flowchart of control voltage correction to the magnetic permeability sensor according to the second embodiment [Figure 16] Graph showing the relationship between the control voltage and the output voltage of the magnetic permeability sensor of Example 2 [Figure 17] FIG. 13 is a table showing the control voltage correction results for the magnetic permeability sensor of Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the following embodiments may be changed as appropriate depending on the configuration of the device to which the present invention is applied and various conditions, and are not intended to limit the scope of the present invention to these alone.

[0016] Example 1 Hereinafter, the image forming apparatus according to the first embodiment will be described in detail with reference to the drawings.

[0017] [Overall configuration and operation of the image forming apparatus] First, the overall configuration and operation of the image forming apparatus of this embodiment will be described. Fig. 1 is a schematic cross-sectional view showing the overall configuration of an electrophotographic image forming apparatus. Fig. 2 is a schematic cross-sectional view showing the schematic configuration of an image forming section.

[0018] The image forming apparatus 100 of this embodiment forms an image on a recording material according to image information from a document reading device connected to the main body of the image forming apparatus 100 or a host device such as a personal computer PC connected to the main body of the image forming apparatus 100 so as to be communicable therewith. For example, a four-color full-color image of yellow (Y), magenta (M), cyan (C) and black (K) is formed on a recording material such as a recording sheet, a plastic sheet or cloth by using an electrophotographic image forming means described later.

[0019] The image forming apparatus 100 of this embodiment is a 4-tandem type image forming apparatus 100, and has a plurality of image forming sections, namely, first, second, third and fourth image forming sections PY, PM, PC and PK, which form images of yellow, magenta, cyan and black, respectively. Then, while an intermediate transfer belt 51, which serves as an intermediate transfer body provided in the transfer device 5, moves in the direction of the arrow in FIG. 2 and passes through each of the image forming sections PY to PK, images of each color are superimposed on the intermediate transfer belt 51 at each of the image forming sections PY to PK. Then, a recorded image is obtained by transferring the superimposed multiple toner images on this intermediate transfer belt 51 to a recording material.

[0020] In the following embodiment, the configurations of the image forming units PY, PM, PC, and PK are substantially the same except for the different developing colors. Hereinafter, unless a particular distinction is required, the suffixes Y, M, C, and K given to the reference numerals to indicate that the element belongs to any one of the image forming units PY to PK will be omitted, and the image forming unit will be generally described as the image forming unit P.

[0021] The image forming section P has a photosensitive drum 1 made of a drum-shaped photosensitive body as an electrostatic latent image carrier that carries an electrostatic latent image according to image information. On the outer periphery of the photosensitive drum 1, a charging roller 2 as a charging device, an exposure device 3 made of a laser exposure optical system, a developing device 4, a transfer device 5, and a cleaning device 6 are provided. A toner container (toner cartridge) 8 is a replaceable container that contains a developer to be replenished to the developing device 4. The transfer device 5 has an intermediate transfer belt 51 as an intermediate transfer body. The intermediate transfer belt 51 is wound around a plurality of rollers and rotates in the direction of the arrow in FIG. 2. A primary transfer member 52 is disposed at a position facing each photosensitive drum 1 via the intermediate transfer belt 51. A secondary transfer member 53 is disposed at a position facing one of the rollers around which the intermediate transfer belt 51 is wound.

[0022] When forming an image, first, the surface of the rotating photosensitive drum 1 is uniformly charged by the charging roller 2. Next, the charged surface of the photosensitive drum 1 is scanned and exposed by the exposure device 3 in response to an image information signal, thereby forming an electrostatic latent image on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is visualized as a toner image by the developing device 4 using toner as a developer.

[0023] The toner image formed on the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 51 by the action of a primary transfer bias voltage applied to a primary transfer member 52 in a primary transfer nip portion where the intermediate transfer belt 51 and the photosensitive drum 1 come into contact with each other. For example, when a four-color full-color image is formed, a toner image is transferred from each photosensitive drum 1 onto the intermediate transfer belt 51 in sequence from the image forming portion PY, and a multiple toner image in which the four color toner images are superimposed on the intermediate transfer belt 51 is formed.

[0024] Meanwhile, the recording material contained in the feeding cassette 9 is transported by a pickup roller, a transport roller, a registration roller, etc., in synchronization with the toner image on the intermediate transfer belt 51 to the secondary transfer nip portion where the intermediate transfer belt 51 and secondary transfer member 53 abut against each other. Then, the multiple toner image on the intermediate transfer belt 51 is transferred onto the recording material in the secondary transfer nip portion by the action of a secondary transfer bias voltage applied to the secondary transfer member 53.

[0025] Thereafter, the recording material separated from the intermediate transfer belt 51 is conveyed to the fixing device 7. The toner image transferred onto the recording material is melted and mixed by being heated and pressed by the fixing device 7, and is fixed onto the recording material. Thereafter, the recording material is discharged outside the apparatus.

[0026] Any toner or other deposits remaining on the photosensitive drum 1 after the primary transfer process are collected by the cleaning device 6. This prepares the photosensitive drum 1 for the next image forming process. In addition, any toner or other deposits remaining on the intermediate transfer belt 51 after the secondary transfer process are removed by the intermediate transfer body cleaner 54.

[0027] Incidentally, the image forming apparatus 100 of this embodiment is also capable of forming a monochrome or multi-color image, such as a monochrome black image, by using image forming units for a desired monochrome color or for several of the four colors.

[0028] [Control Unit] As shown in FIG. 3, the image forming apparatus 100 of this embodiment has a control unit 10, and the control unit 10 controls the operation of each unit of the image forming apparatus 100. The control unit 10 will be described using FIG. 3 with reference to FIG. 2. FIG. 3 is a block diagram showing a system configuration for controlling the image forming apparatus 100. Note that the control unit 10 is also connected to a photosensitive drum, a charging roller, a laser light emitting element, a developing device, a primary transfer roller, a cleaner, an intermediate transfer belt, a fixing device, etc., as well as motors and power supplies for driving them, but illustrations and explanations are omitted here as they are not the main point of the invention. Also, in order to make the explanation easier to understand, the image forming unit PK will be described as an example.

[0029] The control unit 10 as a control means has a central processing unit (CPU) 206, a read only memory (ROM) 210, and a random access memory (RAM) 211. The ROM 210 stores various programs and data, such as an image forming job process, a supply control process for supplying toner to the developing device 4K, and an initialization control process for the magnetic permeability sensor 45 (see FIG. 8 described later). The CPU 206 can execute the various programs stored in the ROM 210 and can execute them to operate the image forming apparatus 100. Working data and input data are stored in the RAM 211 as a main body storage unit. The CPU 206 can refer to the data stored in the RAM 211 based on the various programs.

[0030] In this embodiment, the control unit 10 is connected to the magnetic permeability sensor 45, a sensor power supply / control unit 70 that applies a voltage to the magnetic permeability sensor 45 and inputs an output value from the magnetic permeability sensor 45, and the like. The sensor power supply / control unit 70 includes a power supply that applies a power supply voltage to the magnetic permeability sensor 45 and applies a control voltage (Vcnt) while the power supply voltage is being applied. With a voltage applied by the sensor power supply / control unit 70, the magnetic permeability sensor 45 can output an output voltage whose value changes depending on the toner concentration of the developer contained in the developing device 4K.

[0031] The control unit 10 has a replenishment control unit 150. The replenishment control unit 150 replenishes the replenishment agent from the toner container 8 to the developing device 4K through the toner bottle motor drive control unit 190, so as to maintain the toner concentration of the developer contained in the developing device 4K at a target concentration, based on the output voltage output from the magnetic permeability sensor 45. The details of the replenishment amount control will be described later.

[0032] An external input interface 200 (external input I / F) is connected to an external device (not shown) such as a document reader or a computer so as to be capable of data communication, and inputs color image data as RGB image data from these devices as necessary. A LOG conversion unit 201 converts the luminance data of the image data in RGB format input via the external input interface 200 into density data in CMYK format (CMYK image data) based on a look-up table (LUT) stored in a ROM 210. A masking / UCR unit 202 extracts black (Bk) component data from the converted CMYK image data, and performs matrix calculations on the CMYK image data to correct color impurities in the recording color materials.

[0033] An LUT unit (lookup table unit) 203 adjusts the CMYK image data to the ideal gradation characteristics of a printer control unit 209. Specifically, using a lookup table, density correction is performed for each color of the CMYK image data input from the masking / UCR unit 202. The lookup table is created based on data expanded on a RAM 211, and the table contents are set by a CPU 206. A pulse width modulation unit 204 outputs a pulse signal having a pulse width corresponding to the level of the CMYK image data input from the LUT unit 203. Based on this pulse signal, a laser driver 205 drives a laser light emitting element 3K to irradiate the photosensitive drum 1K with laser light, thereby forming an electrostatic latent image on the photosensitive drum 1K (see FIG. 1).

[0034] The video signal count unit 207 integrates the level (0 to 255 level) of each pixel of the image data input to the LUT unit 203 at, for example, 600 dpi for one surface of the image. This integrated image data value is called a video count value. This video count value is the maximum value "529" when the entire surface of an output image, for example, one side of an A4 sheet, is at the "255" level. When there is a limit in the circuit configuration, it is possible to obtain the video count value by similarly calculating the image signal from the laser driver 205 using a laser signal count unit 208 instead of the video signal count unit 207. The video count value signal is input to the printer control unit 209. Based on the signal, the printer control unit 209 performs various controls such as controlling the rotation speed of the developer carrier 44 and screw members 41d and 41e described later.

[0035] [Basic configuration of developing device] Next, the configuration of the developing device 4 will be further described with reference to Figures 4 and 5. Figure 4 is a schematic cross-sectional view showing the developing device. Figure 5 is a schematic top view showing the developing device.

[0036] In addition, since the configuration of each image forming unit PY, PM, PC, PK is essentially the same except for the developing color, the subscripts Y, M, C, K given to the symbols to indicate that the element belongs to any of the image forming units PY to PK are omitted, and they will be described collectively as image forming unit P.

[0037] The developing device 4 has a developing container 41 that contains a two-component developer comprising a non-magnetic toner and a magnetic carrier. In this embodiment, the developer contained in the developing container 41 is a two-component developer in which a negatively charged non-magnetic toner and a magnetic carrier are mixed. The non-magnetic toner is a resin such as polyester or styrene that contains colorants, wax components, etc., and is pulverized or polymerized to form a powder. Furthermore, the resin contains crystalline polyester, which gives it a low melting point and enables low-temperature fixing. The magnetic carrier is a core made of resin particles kneaded with ferrite particles and magnetic powder, with a resin coating applied to the surface layer.

[0038] The developing container 41 is provided with a developer carrier 44 as a developer carrier, and a magnet roll 44a made of a magnet as a magnetic field generating means fixedly disposed within the developer carrier 44. Further, a regulating blade 42 that forms a thin layer of developer on the surface of the developer carrier 44, and screw members 41d and 41e that stir and transport the developer in the developing container 41 are also disposed.

[0039] The inside of the developing container 41 is divided into a developing chamber 41a and an agitating chamber 41b by a partition wall 41c extending in the vertical direction. A screw member 41d is disposed in the developing chamber 41a, and a screw member 41e is disposed in the agitating chamber 41b. Transfer portions 41f and 41g that allow the passage of the developer between the developing chamber 41a and the agitating chamber 41b are provided at both longitudinal ends of the partition wall 41c.

[0040] In this embodiment, the screw members 41d and 41e are each formed by providing a spiral blade as a transport section around a magnetic shaft (rotation shaft). In addition to the spiral blade, the screw member 41e is provided with an agitating rib that protrudes from the shaft in the radial direction and has a predetermined width in the developer transport direction. The agitating rib agitates the developer as the shaft rotates.

[0041] The screw member 41d agitates and transports the developer in the developing chamber 41a. The screw member 41e equalizes the toner concentration under automatic toner replenishment control (hereinafter referred to as "ATR: Automatic Toner Replenisher" control). That is, the screw member 41e agitates and transports the replenishment developer, which is made up of toner and carrier supplied at the replenishing port 43, and the developer, which is made up of toner and magnetic carrier already in the agitation chamber 41b, to equalize the toner concentration.

[0042] The screw members 41d and 41e are disposed substantially parallel to the direction of the rotation axis of the developer carrier 44. The screw members 41d and 41e transport the developer in opposite directions to each other along the direction of the rotation axis of the developer carrier 44. In this manner, the developer is circulated in the developing container 41 by the screw members 41d and 41e through the delivery portions 41f and 41g. That is, the developer in the developing chamber 41a, in which the toner has been consumed in the developing process and the toner concentration has decreased, moves into the stirring chamber 41b through one of the delivery portions 41f by the transport force of the screw members 41d and 41e.

[0043] In addition, a supply port 43 for supplying toner is provided at the most upstream part of the stirring chamber 41b, and is connected to a toner container 8, which is a supply container for storing the supply toner shown in FIG. 5. Then, the operation of the toner container 8 is controlled according to the image ratio during image formation by the above-mentioned ATR control, the magnetic permeability sensor 45 as a toner concentration sensor, and the density detection result of the patch image by the toner patch concentration sensor 55, and the toner is supplied to the most upstream part of the stirring chamber 41b. Then, the developer in the stirring chamber 41b, which has been supplied with the toner and stirred, moves to the developing chamber 41a through the other delivery section 41g. In addition, the developing chamber 41a of the developing device 4 has an opening at a position corresponding to the developing area facing the photosensitive drum 1, and a developer carrier 44 is rotatably arranged so as to be partially exposed at the opening 41j of the developing container 41. In this embodiment, the developer carrier 44 is made of a non-magnetic material and rotates in the direction of the arrow in FIG. 4 during the developing operation. A magnet roll 44a having a plurality of magnetic poles arranged in the circumferential direction is fixed inside the developer carrier 44 as a magnetic field generating means.

[0044] The developer in the developing chamber 41a is supplied to the developer carrier 44 by the screw member 41d. A predetermined amount of the developer supplied to the developer carrier 44 is carried on the developer carrier 44 by the attraction magnetic pole S2 generated by the magnet roll 44a, forming a developer pool. As the developer carrier 44 rotates, the two-component developer on the developer carrier 44 is transported to the layer thickness regulating magnetic pole N1, where the layer thickness is regulated by the regulating blade 42, and is transported to a developing area facing the photosensitive drum 1. In the developing area, the developer on the developer carrier 44 stands up at the developing magnetic pole S1 to form magnetic ears.

[0045] In the development area, the developer contacts the photosensitive drum 1 and supplies toner to the electrostatic latent image formed on the photosensitive drum 1 to develop the toner image. At this time, in order to improve the development efficiency, that is, to improve the rate at which toner is applied to the electrostatic latent image, a development voltage consisting of a DC voltage superimposed on an AC voltage is applied from a power source (not shown) to the developer carrier 44. As an example, a superimposed voltage consisting of a DC voltage of -500 [V] and an AC voltage with a peak-to-peak voltage of 1500 [V] and a frequency of 12 [kHz] is applied as the development voltage. Generally, in the two-component magnetic brush development method, the application of an AC voltage increases the development efficiency and produces a high-quality image, but conversely, fogging is more likely to occur. For this reason, fogging is prevented by providing a potential difference between the DC voltage applied to the developer carrier 44 and the charged potential of the photosensitive drum 1.

[0046] Thereafter, the developer on the developer carrier 44 is transported into the developing device by the transport magnetic pole N2, which maintains the developer on the surface of the developer carrier 44 and transports the developer to the inside of the developing device, and the developer is separated from the surface of the developer carrier by the separation magnetic pole S3.

[0047] The developing device 4 is provided with a developing device memory 90 (see FIG. 3) as a setting storage unit. The developing device memory 90 is a non-volatile memory provided in the developing device 4. The developing device memory 90 stores information such as the manufacturing number of the developing device, the manufacturing date, the total operating time, and whether or not the developing device is new.

[0048] [Basic configuration of the supply device] The configuration of the replenishing device will be described with reference to Fig. 6. Fig. 6 is a schematic diagram showing the configuration of the replenishing device. The configuration of the replenishing device is based on a configuration in which a replenishing transport path 83 extends from an outlet 82 of a toner container 8 and is connected to a replenishing port 43 of a developing device 4.

[0049] As described above, the image forming apparatus 100 has the replaceable toner container 8 that contains the developer to be replenished to the developing device 4. The control unit 10 controls the supply of developer from the toner container 8 to the developing device 4 based on the output voltage output from the magnetic permeability sensor 45, so as to maintain the toner concentration of the developer contained in the developing device 4 at a target concentration.

[0050] A replenishment developer is stored in the toner storage container 8. The replenishment developer has a higher toner ratio (for example, 90%) than a carrier ratio (for example, 10%).

[0051] In the above-described developing device 4, the supply port 43 is provided at the most upstream of the stirring chamber 41b and outside the developer circulation path. There is almost no developer in the developer circulation path in the developer transport member near the supply port 43, and only the supply developer supplied from the toner container 8 passes through. The supply port 43 is connected to the lower end of the cylindrical member with a square cross section that is the supply transport path 83. The upper end of the cylindrical member that is the supply transport path 83 is connected to the discharge port 82 of the toner container 8.

[0052] The toner container 8 is a cylindrical container with a spiral groove dug in the inner wall, and the toner container 8 itself rotates to generate a transport force in the longitudinal direction to transport the replenishment developer to the discharge port 82. The replenishment developer transported to the discharge port 82 is discharged through the discharge port 82 to the replenishment transport path 83 by air pressure generated by a pump 81 that varies the volume inside the toner container. The replenishment developer then reaches the replenishment port 43 of the developing device 4 through the replenishment transport path 83.

[0053] [Magnetic permeability sensor] Next, the magnetic permeability sensor 45 will be described. As described above, the developer used in this embodiment is a two-component developer containing non-magnetic toner and magnetic carrier. When the toner concentration of this developer changes, the magnetic permeability also changes according to the mixture ratio of the non-magnetic toner and the magnetic carrier. Therefore, if the magnetic permeability change is detected by the magnetic permeability sensor 45, the toner concentration of the developer can be detected. The magnetic permeability sensor 45 used in this embodiment is capable of outputting an output voltage according to the change in magnetic permeability of the developer, that is, the toner concentration, by utilizing the inductance of a coil.

[0054] Although not shown, the magnetic permeability sensor 45 is wired with four wires: a wire for applying a predetermined power supply voltage (e.g., 5.0 V), a wire for applying a control voltage, a wire for earthing, and a wire for output voltage. A power supply voltage is applied to the magnetic permeability sensor 45 from the sensor power supply / control unit 70 (see FIG. 3), and a control voltage is applied while the power supply voltage is being applied. With a voltage being applied by the sensor power supply / control unit 70, the magnetic permeability sensor 45 detects the magnetic permeability of the developer in the vicinity of the sensor surface 45s (i.e., the toner concentration of the developer).

[0055] The magnetic permeability sensor 45 is disposed downstream of the stirring chamber 41b as shown in Fig. 5. The magnetic permeability sensor 45 is configured to detect developer in a sufficiently stirred state in which the developer circulated from the development chamber 41a to the stirring chamber 41b is mixed with the replenishment developer newly replenished from the replenishing port 43. This prevents erroneous detection of the toner concentration due to insufficient stirring.

[0056] The magnetic permeability sensor 45 detects the developer being stirred by the screw member 41e in the stirring chamber 41b at time intervals of the order of 1 msec. At this time, there are times when the amount of developer near the sensor surface 45s is large and times when it is small due to the shape of the spiral blade of the screw member 41e. Therefore, when the output voltage [V] of the magnetic permeability sensor 45 is plotted with time [s] on the horizontal axis, the shape becomes a waveform as shown in FIG. 7. In this embodiment, the average of three wavelengths of the waveform is taken as the "output voltage of the magnetic permeability sensor 45" and is treated as the detection result of the magnetic permeability sensor 45. In all controls using the detection result of the magnetic permeability sensor 45 in this embodiment, the detection result that has undergone this processing is used.

[0057] When the toner concentration of the developer in the developing device 4 decreases, the ratio of magnetic carriers contained in the developer per unit volume in the vicinity of the sensor surface 45s increases relatively, the apparent magnetic permeability of the developer increases, and the output voltage of the magnetic permeability sensor 45 increases. Conversely, when the toner concentration of the developer increases, the ratio of magnetic carriers contained in the developer per unit volume in the vicinity of the sensor surface 45s decreases relatively, the apparent magnetic permeability of the developer decreases, and the output voltage of the magnetic permeability sensor 45 decreases.

[0058] The output voltage output by the magnetic permeability sensor 45 varies depending on the bulk density of the developer, even when developer with the same toner concentration is present near the sensor surface 45s. For example, in a high-temperature, high-humidity environment, the toner charge of the developer decreases, so that the Coulomb repulsive force between toner particles or carrier particles decreases, and the bulk density of the developer increases. On the other hand, in a low-temperature, low-humidity environment, the toner charge of the developer increases, so that the Coulomb repulsive force between toner particles or carrier particles increases, and the bulk density of the developer decreases. For this reason, even with developer with the same toner concentration, the output voltage is likely to be higher in a high-temperature, high-humidity environment than in a low-temperature, low-humidity environment.

[0059] Furthermore, for example, when the process speed is changed when the recording material is switched from plain paper to thick paper and an image is formed, the rotation speed of the developer carrier 44 or the screw members 41d and 41e changes, which may also change the bulk density of the developer near the sensor surface 45s of the magnetic permeability sensor 45. Specifically, when the rotation speed of the developer carrier 44 or the screw members 41d and 41e slows down, the bulk density tends to increase.

[0060] Therefore, the control voltage (e.g., 3.0 to 5.0 V) applied to the magnetic permeability sensor 45 for proper concentration detection is changed depending on the installation environment (e.g., temperature, humidity, absolute moisture content, etc.) of the image forming apparatus 100, the process speed, etc.

[0061] [Initialization control process] Next, the initialization control of the developing device 4 will be described with reference to Fig. 8. Fig. 8 is a flowchart of the initialization control of the developing device.

[0062] As described above, the developing device is equipped with a magnetic permeability sensor to detect the toner concentration. The magnetic permeability sensor can output an output voltage according to the magnetic permeability of the developer when a voltage is applied. However, the magnetic permeability sensors attached to each developing device have individual differences in the "relationship between the control voltage and the output voltage" due to variations in the magnetic permeability sensors, variations in the installation in the developing device, variations in the control voltage applied to the magnetic permeability sensors, etc. In this case, even if the same control voltage is applied to the magnetic permeability sensors attached to each developing device, different output voltages are output from the magnetic permeability sensors attached to each developing device, and as a result, different toner concentrations are detected even though the toner concentrations are the same. In other words, there is a risk that the toner concentration cannot be detected correctly.

[0063] Therefore, the control unit 10 can execute an initialization mode in which the control voltage applied to the magnetic permeability sensor 45 is adjusted (set) so that the same output voltage is output for developers with the same toner concentration. Here, the initialization mode that the control unit 10 can execute is an initialization control process that initializes the magnetic permeability sensor 45 when the image forming apparatus 100 is installed for the first time after being shipped from the factory (initial installation) or when the developing device 4 is replaced with a new one, and is the initialization control process shown in FIG.

[0064] The developing device memory 90 of a new developing device 4 stores an initial flag ON when shipped from the factory. Here, the developing device 4 in which the initial flag ON is stored in the developing device memory 90 is a new developing device that contains an initial developer having a predetermined toner concentration. The initial developer having a predetermined toner concentration is an initial developer that has been adjusted to a target concentration beforehand when shipped from the factory. A new developing device 4 contains an initial developer in which the ratio of carrier (e.g., 90%) is higher than the ratio of toner (e.g., 10%).

[0065] When the power supply of the image forming apparatus 100 is turned on, the control unit 10 detects that the initial flag of the developing device storage memory 90 is ON (S101), and determines that the developing device 4 installed in the image forming apparatus 100 is a brand new developing device, and starts initialization control (S102).

[0066] Next, the control unit 10 drives the screw member of the developing device 4 to perform an operation of stirring the initial developer for a predetermined time (for example, 1 [min]) and stabilizes the charge amount of the developer contained in the developing device 4 (S103). At this time, in order to prevent a change in toner concentration due to the toner in the developer flying to the photosensitive drum 1, a voltage is applied to the developer carrier 44 and the photosensitive drum 1 to create a potential difference.

[0067] Next, the control unit 10 changes the control voltage applied to the magnetic permeability sensor 45 within a predetermined range, for example, by "0.1 [V]" at a time, and obtains an output voltage from the magnetic permeability sensor 45 that is output in response to the change. The new developing device 4 contains an initial developer that has been adjusted to a target density beforehand at the time of shipment from the factory. The control voltage when the new developing device 4 obtains an output voltage (here, 2.0 [V]) that is predetermined according to the target density at the time of shipment from the factory is set as the control voltage Vcnt1 to be applied to the magnetic permeability sensor 45 for proper density detection (S104). The set control voltage Vcnt1 and the initial flag OFF are then stored in the developing device storage memory 90 (S105), and the initialization control process is terminated (S106).

[0068] In this way, the developing device memory 90 of the developing device 4 stores the initial flag ON if the developing device is a new developing device that has not been subjected to the initialization mode, and stores the initial flag OFF if the developing device has been subjected to the initialization mode. In other words, the developing device memory 90 of the developing device 4 has information on whether or not the initialization mode has been performed.

[0069] In this embodiment, the start of initialization control is determined based on the initial flag in the developing device storage memory 90, but this is not limited to this. For example, initialization control may be started by manually pressing a button on the image forming device after replacing the developing device.

[0070] [Replenishment amount control] In this embodiment, the supply of developer to the developing device 4 is performed by ATR control. In this supply control, the amount and state of toner in the developer are detected and estimated, and based on this, the supply control unit 150 calculates the necessary supply amount and automatically supplies developer to the developing device 4 at an appropriate timing. Here, the appropriate timing is the timing when a mass of developer in which toner has been consumed by image formation and the toner concentration has decreased circulates inside the developing device 4 and reaches the vicinity of the supply port 43.

[0071] In the ATR control of this embodiment, the amount of toner to be replenished is calculated by adding together the replenishment amount calculation based on the estimation of the amount of toner consumed using the video count value and the replenishment amount calculation based on the detection result of the toner concentration by the magnetic permeability sensor 45. Hereinafter, the replenishment amount calculation based on the estimation of the amount of toner consumed using the video count value (replenishment amount control) is referred to as video count replenishment control. The replenishment amount calculation based on the detection result of the toner concentration by the magnetic permeability sensor 45 is referred to as inductance replenishment control.

[0072] At this time, the toner concentration output value target to be aimed for is not always constant, and control is performed as appropriate to form a toner patch on intermediate transfer belt 51 under latent image conditions determined in the initialization control process, and detect its density using toner patch density sensor 55 (see Figures 2 and 3). Hereinafter, this control is referred to as toner patch control. By appropriately performing this toner patch control, the toner concentration output value target to be aimed for is constantly being corrected. Toner patch density sensor 55 measures the density of the toner patch by irradiating light onto the toner patch formed on intermediate transfer belt 51 using an LED, and detecting the amount of reflected light (specularly reflected light or diffusely reflected light).

[0073] Detailed system configurations of the video count supply control and the inductance supply control will be described with reference to Fig. 3 and Fig. 9. Fig. 9 is a block diagram showing the system configuration of the toner supply control of the image forming apparatus. The toner supply amount is calculated in units of mass [mg] of the supply agent by adding up the supply amounts calculated in the video count supply control and the inductance supply control.

[0074] In the video count supply control, first, the video count value acquired by the video signal count unit 207 of the control unit 10 is sent to the video count supply control unit 160 of the supply control unit 150. The video count value is converted into the mass of the developer to be supplied by a conversion table held by the video count supply control unit 160, and the supply amount is calculated based on the converted value. On the other hand, in the inductance supply control, the output voltage output by the magnetic permeability sensor 45 according to the toner concentration is input to the inductance supply control unit 170 of the supply control unit 150. The output voltage value is AD converted in the inductance supply control unit 170 to become an 8-bit digital signal value (hereinafter, this digital signal value is referred to as the toner concentration output value). The supply amount is calculated by multiplying the deviation between the toner concentration output value and the toner concentration output value target by the inductance supply coefficient Y. Here, the toner concentration output value target is determined in the toner patch control unit 180 of the supply control unit 150 according to the output value of the toner patch concentration sensor 55 as described above.

[0075] The total replenishment amount calculated by video count replenishment control unit 160 and inductance replenishment control unit 170 is sent to toner bottle motor drive control unit 190, and the toner container 8 is operated to replenish the necessary amount. Here, video count replenishment control is feedforward control, and the replenishment amount is always calculated as a positive value, whereas inductance replenishment control is feedback control that detects the toner concentration in developing device 4 by magnetic permeability sensor 45 and calculates positive and negative values. By adjusting the replenishment amount in the video count replenishment control using inductance replenishment control, it is possible to suppress fluctuations in the toner concentration in developing device 4.

[0076] [Permeability sensor sensitivity correction] There are individual differences in the sensor sensitivity of the magnetic permeability sensors 45, and individual differences arise in the output values ​​for developers with the same toner concentration. For example, magnetic permeability sensor 45b, which has a lower sensor sensitivity than reference magnetic permeability sensor 45a, and magnetic permeability sensor 45c, which has a higher sensor sensitivity than magnetic permeability sensor 45a, are brought close to multiple magnetic bodies A, B, and C with different amounts of magnetization, and the output values ​​obtained from magnetic permeability sensor 45 are shown in Fig. 10. At this time, the voltage applied to each magnetic permeability sensor 45 is adjusted so that the output value obtained from magnetic body B is 2.0 [V].

[0077] 10, it can be seen that even if the output value of magnetic permeability sensor 45 is the same, the amount of magnetization, i.e., the toner concentration in developing device 4, varies depending on the sensor sensitivity of magnetic permeability sensor 45, and therefore a correction must be added to the calculation of the replenishment amount. The sensor sensitivity of magnetic permeability sensor 45 is measured during the manufacturing process by bringing magnetic permeability sensor 45 close to multiple magnetic bodies A, B, and C with different amounts of magnetization, to obtain the same data as in FIG. 10. From this data, the inclination of magnetic permeability sensor 45 is calculated and stored as magnetic permeability sensor sensitivity X1 in developing device storage memory 90 of developing device 4. Also, the magnetic permeability sensor sensitivity of reference magnetic permeability sensor 45a=X0.

[0078] The amount of replenishment in the above-mentioned inductance replenishment control is calculated by the following formula using a correction coefficient Y calculated in advance by changing the toner concentration of the developer in the developing device 4 using the standard magnetic permeability sensor 45a.

[0079] Supply amount = (Toner concentration output value - Toner concentration output value target) x Y x X0 / X1

[0080] The magnetic permeability sensor sensitivity, which is the inherent sensitivity characteristic of the magnetic permeability sensor 45 described above, is stored in the developing device storage memory 90 of the developing device 4. Then, the control unit 10 calculates the replenishment amount by the above formula. That is, the control unit 10 calculates the replenishment amount of replenishment developer from the toner container 8 to the developing device 4 based on the output value of the magnetic permeability sensor and the inherent sensitivity characteristic of the magnetic permeability sensor.

[0081] [Control process of image forming device] Next, a description will be given of a characteristic control process of the image forming apparatus 100 of this embodiment. In the image forming apparatus 100 of this embodiment, when a second-hand developing device 4 used in another image forming apparatus is installed in the image forming apparatus 100 and used, the control voltage to the magnetic permeability sensor 45 is reset.

[0082] As described above, the optimum value of the control voltage to the magnetic permeability sensor 45 varies due to individual variations in the magnetic permeability sensor 45, variations in installation in the developing device 4, and variations in the control voltage. Therefore, when a used developing device used in another image forming device is installed in the image forming device 100, even if the control voltage determined in the initialization control process is used, the voltage applied to the magnetic permeability sensor 45 may deviate from the optimum value due to variations in the control voltage of the image forming device. Furthermore, since the exact toner concentration of the developer contained in a used developing device is unknown, it is not possible to execute the initialization control process again.

[0083] Incidentally, the initial developer contained in a new developing device has, for example, a toner ratio of 10% and a carrier ratio of 90%. In contrast, a used developing device does not contain an initial developer, and even if a developer is contained, its toner concentration is unknown. For example, the developer contained in a used developing device has a carrier ratio different from that of the initial developer, for example, a toner ratio of 8% and a carrier ratio of 92%.

[0084] Therefore, in the image forming apparatus of this embodiment, the sensor power supply / control unit 70 is measured in advance during the manufacturing process, and the set value of the control voltage is corrected based on the stored control voltage variation specific to the image forming apparatus. The control voltage variation value α is measured during the manufacturing process at the factory and stored in the RAM 211, which is the main body storage unit of each image forming apparatus. For example, as shown in FIG. 11, the voltage value of the control voltage applied to the magnetic permeability sensor 45 for the preset control voltage changes according to the control voltage variation value α stored in the RAM 211.

[0085] Next, the setting of the control voltage when the developing device 4 used in another image forming apparatus 100A is used in the image forming apparatus 100B will be described with reference to Figs. 12 and 13. Fig. 12 is a flowchart showing the setting control of the control voltage to the magnetic permeability sensor 45 in the first embodiment. Fig. 13 is a table showing the setting result of the control voltage to the magnetic permeability sensor 45 in the first embodiment.

[0086] First, the initial installation flow (S201 to S207 shown in FIG. 12) of a new developing device 4 will be described. Since S201, S202, S203, and S204 shown in FIG. 12 are the same operations as S101, S102, S103, and S104 shown in FIG. 8 described above, the description thereof will be omitted.

[0087] After determining the control voltage Vcnt1 to be applied to the magnetic permeability sensor 45 (S204), the control voltage variation value α1 [%] is read from the RAM 211 of the image forming apparatus 100A (S205). Then, the determined control voltage Vcnt1 and the read control voltage variation value α1 [%] are stored in the developing device storage memory 90 of the developing device 4 (S206). Finally, the initial flag OFF is stored in the developing device storage memory 90 of the developing device 4, and the initialization control is terminated (S207).

[0088] The initialization control operation up to this point is the same as the initialization control described in Figure 8, except that the control voltage variation value α1 is read from RAM 211 and stored in the developing device storage memory 90, and the replenishment control during normal operation is also the same, using the control voltage Vcnt1.

[0089] Next, an operation will be described when a second-hand developing device 4 that has been used in another image forming apparatus is installed in the image forming apparatus 100B.

[0090] When the power supply of the image forming apparatus 100B is turned on, the control unit 10 detects that the initial flag of the developing device memory 90 of the installed developing device 4 is OFF (S201), and determines that the developing device 4 installed in the image forming apparatus 100B is the used developing device. Since the initial flag OFF is stored in the developing device memory 90 of the developing device 4 in S207, the initialization control from S202 to S207 has been executed for this developing device 4.

[0091] When the control unit 10 detects that the initial flag of the developing device storage memory 90 is OFF (S201), it checks whether the developing device-specific serial number stored in the developing device storage memory 90 of the developing device 4 has changed from the serial number used last time (S208).

[0092] Although the manufacturing number unique to the developing device is exemplified as the identification number unique to the developing device stored in the developing device storage memory 90 of the developing device 4, the identification number is not limited to this.

[0093] When the serial number unique to the developing device stored in the developing device memory 90 of the developing device 4 does not change, the control unit 10 returns to normal operation with the control voltage Vcnt unchanged since the developing device 4 has not been replaced.

[0094] On the other hand, when the control unit 10 determines that a different developing device 4 has been installed based on the developing device-specific serial number stored in the developing device memory 90 of the developing device 4 (S208), it resets the control voltage (S209 to S211).

[0095] The control unit 10 reads out the control voltage Vcnt1 [V] and the control voltage variation value α1 [%] from the developing device memory 90 of the developing device 4 in which the initialization mode has been executed, and reads out the control voltage variation value α2 [%] from the RAM 211 of the image forming device 100B (S209).

[0096] Here, the control voltage Vcnt1 [V] stored in the developing device memory 90 of the developing device 4 in which the initialization mode has been executed is the control voltage set in the initialization mode in another image forming apparatus 100A. Also, the variation value α1 [%] of the control voltage stored in the developing device memory 90 is read from the RAM 211 of the other image forming apparatus 100A and stored in the developing device memory 90 when the initialization mode is executed in the other image forming apparatus 100A.

[0097] Then, the control unit 10 calculates an optimal control voltage Vcnt2 based on the control voltage Vcnt1 [V], the control voltage variation value α1 [%], and the control voltage variation value α2 [%] using the following formula 1 (S210).

[0098] [Formula 1] Vcnt2=Vcnt1×(1+α1 / 100) / (1+α2 / 100)

[0099] The control voltage Vcnt2 [V] calculated by the above formula 1 is the control voltage applied to the magnetic permeability sensor 45 of the developing device 4 in which the initialization mode has been executed. In other words, the control voltage Vcnt2 [V] is the control voltage applied to the developing device 4 when the developing device 4 used in another image forming apparatus 100A is installed and used in the image forming apparatus 100B.

[0100] The control unit 10 resets the calculated control voltage Vcnt2 [V] in the developing device storage memory 90 of the developing device 4 for which the initialization mode has been executed (S211), and returns to normal operation.

[0101] For example, when initialization control is performed so that the output voltage becomes 2.0 [V] in the image forming apparatus 100A with the control voltage variation value α1=1.0 [%], the control voltage Vcnt1 to the magnetic permeability sensor 45 of the developing device 4 installed in the image forming apparatus 100A becomes 4.0 [V]. The developing device 4 in which the control voltage Vcnt1 [V] and the control voltage variation value α1 [%] are stored in the developing device storage memory 90 is installed in the image forming apparatus 100B with the control voltage variation value α2=-1.0 [%] and used. In this case, the control voltage Vcnt2 [V] set in the embodiment 1 and the control voltage Vcnt1 [V] set in the comparative example are as shown in the table diagram in FIG. 13.

[0102] The control voltage Vcnt2 [V] set in the first embodiment is calculated by carrying out the control process shown in Fig. 12. On the other hand, the control voltage Vcnt1 [V] set in the comparative example is set by carrying out the control process shown in Fig. 8, and the variation in the control voltage of the image forming apparatus is not corrected.

[0103] In the comparative image forming apparatus 100B, even if the control voltage is set to Vcnt1, the control voltage actually applied to the magnetic permeability sensor 45 is smaller than the value used in the image forming apparatus 100A due to the influence of the variation in the control voltage. Therefore, even though the toner concentration of the developer in the developing device 4 has not changed, the output voltage output by the magnetic permeability sensor becomes smaller.

[0104] In contrast, in the image forming apparatus 100B of the first embodiment, the control voltage Vcnt1 determined in the initialization control of the image forming apparatus 100A is reset to a control voltage Vcnt2 corrected using the control voltage variation value α. Therefore, even if the developing device 4 removed from another image forming apparatus 100A is installed in the image forming apparatus 100B and reused, the control voltage to be applied to the magnetic permeability sensor 45 can be correctly set in the image forming apparatus 100B, and the same output voltage can be obtained.

[0105] According to the present invention, even when the developing device 4 removed from another image forming apparatus 100A is installed in the image forming apparatus 100B and reused, the toner concentration can be correctly detected by the magnetic permeability sensor 45. In other words, even when the developing device 4 that has been subjected to the initialization mode is installed in another image forming apparatus 100 and reused, the toner concentration can be correctly detected by the magnetic permeability sensor 45. By correctly detecting the toner concentration, the developer can be maintained at an optimal toner concentration.

[0106] Example 2 Next, an image forming apparatus according to a second embodiment will be described with reference to the drawings. The schematic configurations of the image forming apparatus, developing device, replenishing device, and magnetic permeability sensor according to this embodiment are the same as those of the above-mentioned embodiment, and therefore will not be described here. In this embodiment, the same reference numerals are used to designate members having the same functions as those of the above-mentioned embodiment.

[0107] [Control process of image forming device] In the above-described first embodiment, when a second-hand developing device 4 that was used in another image forming apparatus is installed in this image forming apparatus, the variation in the control voltage to the magnetic permeability sensor 45 is corrected and the control voltage to the magnetic permeability sensor 45 is reset.

[0108] In the image forming apparatus 100 of this embodiment, when a second-hand developing device 4 used in another image forming apparatus is installed in this image forming apparatus, the control process for resetting the control voltage to the magnetic permeability sensor 45 is different from that of the above-described embodiment 1. The characteristic control process of the image forming apparatus 100 of this embodiment will be described below.

[0109] As described above, the magnetic permeability sensor 45 is applied with a predetermined power supply voltage (here, 5.0 [V]) from the sensor power supply / control unit 70, and with the power supply voltage being applied, a control voltage (Vcnt) is applied, and the magnetic permeability sensor 45 can output an output voltage whose value changes depending on the toner concentration of the developer.

[0110] In this embodiment, the variation in the power supply voltage applied to the magnetic permeability sensor 45 for each image forming apparatus is also corrected to further eliminate the deviation in the supply control. In this embodiment, the magnetic permeability sensor 45 is brought close to the above-mentioned magnetic body B (see FIG. 10) in the manufacturing process of the developing device 4 to measure the output voltage (output value). At this time, the control voltage is adjusted so that the output voltage obtained when the power supply voltage of 5.0 [V] is accurately applied to the magnetic permeability sensor 45 is 2.0 [V], and the output value is measured when the power supply voltage is changed to 4.9 [V] and 5.1 [V]. FIG. 14 shows the relationship between the power supply voltage [V] and the output voltage (output value) [V], which is the measurement result. The sensitivity γ (slope) of the power supply voltage at this time is measured in advance in the manufacturing process and is stored in the developing device storage memory 90 of the developing device 4.

[0111] Also, the power supply voltage of the sensor power supply / control unit 70 is set in advance to a predetermined power supply voltage (here, 5.0 [V]), the value of the power supply voltage actually applied is measured in the manufacturing process, and the measured value, that is, the actual power supply voltage β [V], is stored in the RAM 211. Also, as described above, the control voltage variation value α is a value measured in the manufacturing process at the factory and stored in the RAM 211, which is the main body storage unit of each image forming apparatus. Therefore, the RAM 211 of the image forming apparatus 100B stores the variation value α2 of the control voltage applied from the sensor power supply / control unit 70 to the magnetic permeability sensor 45, which was measured in advance in the manufacturing process, and the actual power supply voltage β2 actually applied to the magnetic permeability sensor 45.

[0112] Setting of the control voltage when a developing device 4 used in another image forming apparatus 100A is used in an image forming apparatus 100B will be described with reference to Figures 15, 16 and 17. Figure 15 is a flowchart showing setting control of the control voltage to the magnetic permeability sensor 45 in the second embodiment. Figure 16 is a graph showing the relationship between the control voltage and the output voltage of the magnetic permeability sensor 45 in the second embodiment. Figure 17 is a table showing the setting result of the control voltage to the magnetic permeability sensor 45 in the second embodiment.

[0113] First, the initial installation flow (S301 to S307 shown in FIG. 15) of a new developing device 4 will be described. Since S301, S302, and S303 shown in FIG. 15 are the same operations as S101, S102, and S103 shown in FIG. 8 described above, the description thereof will be omitted.

[0114] In S304, similarly to S104, the control voltage Vcnt1 to be applied to the magnetic permeability sensor 45 is determined, and at the same time, the sensitivity σ of the control voltage shown in Fig. 16 is calculated. The solid line in Fig. 16 indicates the output value (output voltage [V]) of the magnetic permeability sensor 45 relative to the set value (control voltage Vcnt [V]) in S304. The dashed line in Fig. 16 indicates the output value (output voltage [V]) of the magnetic permeability sensor 45 relative to the actual output of the control voltage corrected by applying the control voltage variation value α1 [%] to the control voltage Vcnt, and the slope of this line indicates the sensitivity σ of the control voltage.

[0115] Next, the control voltage variation value α1 [%] and the actual power supply voltage β1 [V] are read from the RAM 211 of the image forming apparatus 100A (S305). Then, the determined control voltage Vcnt1 [V], the read control voltage variation value α1 [%] and actual power supply voltage β1 [V], and the control voltage sensitivity σ are stored in the developing device storage memory 90 of the developing device 4 (S306). Finally, the initial flag OFF is stored in the developing device storage memory 90 of the developing device 4, and the initialization control is terminated (S307).

[0116] Next, the operation when a second-hand developing device 4 that has been used in another image forming apparatus 100A is installed in the image forming apparatus B will be described.

[0117] When the power supply of the image forming apparatus 100B is turned on, the control unit 10 detects that the initial flag of the developing device memory 90 of the installed developing device 4 is OFF (S301), and determines that the developing device 4 installed in the image forming apparatus 100B is the used developing device. Since the initial flag OFF is stored in the developing device memory 90 of the developing device 4 in S307, the initialization control from S302 to S307 has been executed for this developing device 4.

[0118] When the control unit 10 detects that the initial flag of the developing device storage memory 90 is OFF (S301), it checks whether the developing device-specific serial number stored in the developing device storage memory 90 of the developing device 4 has changed from the serial number used last time (S308).

[0119] When the serial number unique to the developing device stored in the developing device memory 90 of the developing device 4 does not change, the control unit 10 returns to normal operation with the control voltage Vcnt unchanged since the developing device 4 has not been replaced.

[0120] On the other hand, when the control unit 10 determines that a different developing device 4 has been installed based on the developing device-specific serial number stored in the developing device memory 90 of the developing device 4 (S308), it resets the control voltage (S309 to S311).

[0121] The control unit 10 reads out the control voltage Vcnt1 [V], the control voltage variation value α1 [%], the actual power supply voltage β1 [V], and the control voltage sensitivity σ from the developing device memory 90 of the developing device 4 that has been executed in the initialization mode (S309). At the same time, the control voltage variation value α2 [%] and the actual power supply voltage β1 [V] are read out from the RAM 211 of the image forming apparatus 100B (S309).

[0122] Here, the control voltage Vcnt1 [V] and the control voltage sensitivity σ stored in the developing device memory 90 of the developing device 4 in which the initialization mode has been executed are control voltages set in the initialization mode in another image forming apparatus 100A. The control voltage variation value α1 [%] stored in the developing device memory 90 is read from the RAM 211 of the other image forming apparatus 100A and stored in the developing device memory 90 when the initialization mode is executed in the other image forming apparatus 100A. The actual power supply voltage β1 [V] stored in the developing device memory 90 is read from the RAM 211 of the other image forming apparatus 100A and stored in the developing device memory 90 when the initialization mode is executed in the other image forming apparatus 100A. The power supply voltage sensitivity γ of the magnetic permeability sensor 45 stored in the developing device memory 90 is the sensitivity of the output voltage when the power supply voltage applied to the magnetic permeability sensor 45 changes, which is measured in advance in the manufacturing process.

[0123] Then, the control unit 10 calculates an optimal control voltage Vcnt3 [V] based on the control voltage Vcnt1 [V], the control voltage sensitivity σ, the power supply voltage sensitivity γ, the control voltage variation value α1 [%], and the actual power supply voltage β1 [V], as well as the control voltage variation value α2 [%] and the actual power supply voltage β2 [V], using the following equation 2 (S310).

[0124] [Formula 2] Vcnt3=Vcnt1×(1+α1 / 100) / (1+α2 / 100)+(β1-β2)×γ / (σ(1+α2 / 100))

[0125] The control voltage Vcnt3 [V] calculated by the above formula 2 is the control voltage applied to the magnetic permeability sensor 45 of the developing device 4 in which the initialization mode has been executed. In other words, the control voltage Vcnt3 [V] is the control voltage applied to the developing device 4 when the developing device 4 used in another image forming apparatus 100A is installed and used in the image forming apparatus 100B.

[0126] The control unit 10 resets the calculated control voltage Vcnt3 [V] in the developing device storage memory 90 of the developing device 4 for which the initialization mode has been executed (S311), and returns to normal operation.

[0127] For example, when the image forming apparatus 100A with the control voltage variation value α1=1.0[%] and the actual power supply voltage β1=5.1[V] performs initialization control so that the output voltage becomes 3.0[V], the control voltage Vcnt1 to the magnetic permeability sensor 45 of the developing device 4 installed in the image forming apparatus 100A becomes 4.04[V]. The developing device 4 in which the control voltage Vcnt1[V], the control voltage variation value α1[%], and the actual power supply voltage β1[%] are stored in the developing device storage memory 90 is installed in the image forming apparatus 100B with the control voltage variation value α2=-1.0[%] and the actual power supply voltage β2=4.9[V] and used. In this case, the control voltage Vcnt3[V] set in the second embodiment and the control voltage Vcnt2[V] set in the first embodiment are as shown in the table diagram in FIG.

[0128] The control voltage Vcnt3 [V] set in the second embodiment is calculated by performing the control process shown in Fig. 15. The control voltage Vcnt2 [V] set in the first embodiment is calculated by performing the control process shown in Fig. 12.

[0129] At this time, the image forming apparatus 100B of the first embodiment has a power supply voltage sensitivity γ=0.315 and a control voltage sensitivity σ=2.125. In the image forming apparatus 100B of the first embodiment, even if the control voltage Vcnt2 [V] is set, the voltage actually applied to the magnetic permeability sensor 45 becomes smaller than the value used in the image forming apparatus 100A due to the influence of the variation in the power supply voltage. Therefore, even though the toner concentration of the developer in the developing device 4 has not changed, the output voltage output by the magnetic permeability sensor becomes smaller.

[0130] In contrast, in the image forming apparatus 100B of the second embodiment, the control voltage Vcnt1 determined in the initialization control of the image forming apparatus 100A is reset to a control voltage Vcnt3 corrected using the control voltage variation value α and the power supply voltage variation (actual power supply voltage β). Therefore, even if the developing device 4 removed from another image forming apparatus 100A is installed in the image forming apparatus 100B and reused, the control voltage to be applied to the magnetic permeability sensor 45 can be correctly set in the image forming apparatus 100B, and the same output voltage can be obtained.

[0131] According to the present invention, even when the developing device 4 removed from the image forming apparatus 100A is installed in another image forming apparatus 100B and reused, the toner concentration can be correctly detected by the magnetic permeability sensor 45. In other words, even when the developing device 4 that has been subjected to the initialization mode is installed in another image forming apparatus 100 and reused, the toner concentration can be correctly detected by the magnetic permeability sensor 45. By correctly detecting the toner concentration, the developer can be maintained at an optimal toner concentration.

[0132] In the above-described first and second embodiments, the information stored in the developing device memory 90 attached to the developing device 4 is used for correcting the control voltage Vcnt, but the storage unit is not limited to such a physical storage medium. For example, a method may be used in which various information about the developing device 4 is stored and saved on a cloud connected to the image forming apparatus 100 via the Internet. [Explanation of symbols]

[0133] α,α1,α2 …Variation value of control voltage β, β1, β2 … Actual power supply voltage Vcnt, Vcnt1, Vcnt2, Vcnt3 ... Control voltages σ …Control voltage sensitivity γ …Power supply voltage sensitivity P,PY,PM,PC,PK...Image forming section 1, 1Y, 1M, 1C, 1K ... photosensitive drum (image carrier) 4,4Y,4M,4C,4K…Developing device 10...Control section 45... Magnetic permeability sensor 8 ... Toner container (container) 70 ... Power supply for sensor / control unit (power supply) 90 ...Developing device memory (settings memory section) 100, 100A, 100B ... Image forming device 206...CPU 211 ...RAM (main memory)

Claims

1. A developing device that can be attached to and detached from an image forming apparatus, A developer carrier that carries a developer containing toner and a carrier in order to develop an electrostatic latent image formed on an image carrier, A developing container for holding the initial developer, A magnetic permeability sensor capable of outputting an output voltage corresponding to the toner concentration of the developer contained in the developing container when a voltage is applied, The system includes a storage unit that stores information regarding the output characteristics of the power supply of the other image forming apparatus, which has performed an initialization mode that determines the control voltage applied to the magnetic permeability sensor by the power supply of the other image forming apparatus. A developing apparatus characterized by the following features.

2. The storage unit further stores information relating to the control voltage determined in the initialization mode. The developing apparatus according to feature 1.

3. The storage unit further stores information relating to the output characteristics of the power supply of the magnetic permeability sensor. The developing apparatus according to feature 1.

4. The storage unit further stores information regarding whether or not the developing device is new. The developing apparatus according to feature 1.

5. The storage unit further stores unique information that differs for each individual developing device. The developing apparatus according to feature 1.

6. The unique information is the serial number of the developing device. The developing apparatus according to feature 5.

7. A developing device that can be attached to and detached from an image forming apparatus, A developer carrier that carries a developer containing toner and a carrier in order to develop an electrostatic latent image formed on an image carrier, A developing container for holding the initial developer, A magnetic permeability sensor capable of outputting an output voltage corresponding to the toner concentration of the initial developer contained in the developing container when a voltage is applied, The system includes a storage unit that stores information regarding the output characteristics of the power supply of the image forming apparatus, which has performed an initialization mode that determines the control voltage applied to the magnetic permeability sensor by the power supply of the image forming apparatus. A developing apparatus characterized by the following features.

8. The storage unit further stores information relating to the control voltage determined in the initialization mode. The developing apparatus according to feature 7.

9. The storage unit further stores information relating to the output characteristics of the power supply of the magnetic permeability sensor. The developing apparatus according to feature 7.

10. The storage unit further stores information regarding whether or not the developing device is new. The developing apparatus according to feature 7.

11. The storage unit further stores unique information that differs for each individual developing device. The developing apparatus according to feature 7.

12. The unique information is the serial number of the developing device. The developing apparatus according to feature 11.

13. Image carrier and A developing apparatus having a developer carrier that carries a developer containing toner and a carrier for developing an electrostatic latent image formed on the image carrier, a developing container that contains an initial developer, a magnetic permeability sensor that can output an output voltage corresponding to the toner concentration of the developer contained in the developing container when a voltage is applied, and a storage unit, and which is detachable from the image forming apparatus, A power supply for applying voltage to the magnetic permeability sensor, The main unit storage unit stores information regarding the output characteristics of the power supply, The power supply applies a voltage to the permeability sensor and detects the output voltage output from the permeability sensor, thereby enabling the control unit to execute an initialization mode that determines the control voltage to be applied to the permeability sensor by the power supply. The control unit, if the developing device attached to the image forming apparatus has not already performed the initialization mode, performs the initialization mode and reads the information regarding the power supply output characteristics stored in the main unit storage unit and stores it in the storage unit as information regarding the power supply output characteristics of the image forming apparatus that performed the initialization mode. An image forming apparatus characterized by the following:

14. The control unit shall If the developing device attached to the image forming apparatus has not yet performed the initialization mode, Furthermore, the control voltage determined in the initialization mode is stored in the storage unit. The image forming apparatus according to feature 13.

15. The control unit is If the developing device installed in the image forming apparatus has already performed the initialization mode and is different from the developing device that was previously installed in the image forming apparatus, Based on the control voltage determined by the initialization mode stored in the memory unit, information regarding the output characteristics of the power supply of another image forming apparatus that performed the initialization mode stored in the memory unit, and information regarding the output characteristics of the power supply stored in the main unit memory unit, the power supply determines the control voltage to be applied to the magnetic permeability sensor. The image forming apparatus according to feature 14.

16. The storage unit further stores information relating to the output characteristics of the power supply for the magnetic permeability sensor, The control unit, If the developing device installed in the image forming apparatus has already performed the initialization mode and is different from the developing device that was previously installed in the image forming apparatus, Based on the control voltage determined by the initialization mode stored in the storage unit, information regarding the output characteristics of the power supply of another image forming apparatus that performed the initialization mode stored in the storage unit, information regarding the output characteristics of the power supply of the magnetic permeability sensor stored in the storage unit, and information regarding the output characteristics of the power supply stored in the main unit storage unit, the power supply determines the control voltage to be applied to the magnetic permeability sensor. The image forming apparatus according to feature 14.

17. The storage unit further stores information regarding whether or not the developing device is new. The image forming apparatus according to feature 13.

18. The storage unit further stores unique information that differs for each individual developing device. The image forming apparatus according to feature 13.

19. The unique information is the serial number of the developing device. The image forming apparatus according to feature 18.

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