Image forming apparatus

Abstract

This improves detection accuracy compared to conventional toner quantity detection mechanisms. [Solution] The image forming apparatus 200 includes a rotating member 223 provided inside a container 221 for containing toner, a magnetic member 224, a holding member 225 connected to the rotating member and holding the magnetic member 224, a detection unit 226 that outputs a signal corresponding to the distance between itself and the magnetic member 224, a control unit 100, and a storage unit 120. The control unit 100 can acquire first information based on the output of the detection unit 226 when the rotating member 223 is rotating at a first rotational speed and store it in the storage unit 120, and can also acquire second information based on the output of the detection unit 226 when the rotating member 223 is rotating at a second rotational speed slower than the first rotational speed, and store the second information in the storage unit 120 so as to update the first information stored in the storage unit 120 with the second information.

Description

[Technical Field]

[0001] This invention relates to image forming apparatuses such as printers, copiers, and facsimile machines that use electrophotographic or electrostatic recording methods. [Background technology]

[0002] In image forming devices such as printers using the electrophotographic method, the electrostatic latent image formed on the image carrier is developed by a developing device that supplies toner. The image forming device may be equipped with a toner amount detection means for detecting the amount of toner present inside the developing container of the developing device. By detecting the amount of toner inside the developing container, it is possible to inform the user, for example, of the amount of unused toner remaining inside the developing container (toner level), which helps in optimizing the inventory of consumables.

[0003] One method for detecting the amount of toner is to utilize the change in rotational resistance corresponding to the amount of toner inside the container (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 3971330 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The objective of this invention is to improve the detection accuracy compared to conventional toner quantity detection mechanisms. [Means for solving the problem]

[0006] The above objective is achieved by the image forming apparatus according to the present invention. In summary, a typical configuration of the present invention includes an image carrier on which an electrostatic latent image is formed, a container for containing toner, a developing member that supplies the toner contained in the container to the image carrier to develop the electrostatic latent image and form a toner image on the image carrier, a rotating member provided inside the container, a magnetic member, a holding member connected to the rotating member and holding the magnetic member, the holding member moving inside the container while holding the magnetic member as the rotating member rotates, a detection unit that outputs a signal corresponding to the distance between itself and the magnetic member based on the action of magnetism, a drive unit that drives the rotating member to rotate, and the drive unit is controllable to rotate the rotating member at a first rotational speed and a second rotational speed slower than the first rotational speed, and the output of the detection unit The image forming apparatus comprises a control unit that acquires information based on the information and a storage unit that can store the information, wherein the holding member is configured such that the shortest distance between the magnetic member and the detection unit while the rotating member is rotating is shorter when the amount of toner inside the container is a second amount less than the first amount than when the amount of toner inside the container is a first amount, and the control unit is capable of acquiring first information based on the output of the detection unit when the rotating member is rotating at a first rotational speed and storing it in the storage unit, and acquiring second information based on the output of the detection unit when the rotating member is rotating at a second rotational speed, and storing the second information in the storage unit so as to update the first information stored in the storage unit with the second information. [Effects of the Invention]

[0007] According to the present invention, the detection accuracy can be improved compared to conventional toner quantity detection mechanisms. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing the overall configuration of an image forming apparatus. [Figure 2] This is a block diagram illustrating the control configuration of an image forming apparatus. [Figure 3] This is a schematic cross-sectional view of a developing apparatus. [Figure 4] This is a schematic perspective view illustrating the toner quantity detection mechanism. [Figure 5] This graph shows the relationship between the remaining toner amount Tn and the L output period / rotation of the magnetic flux detection unit for each rotational speed of the rotating shaft. [Figure 6] This graph shows the relationship between the remaining toner amount Tn and the rate of change in the L output of the magnetic flux detection unit for each rotational speed of the rotating shaft. [Figure 7] This is a flowchart illustrating an example of the control procedure for Example 1. [Figure 8] This is a schematic cross-sectional view of a developing apparatus to illustrate a modified toner quantity detection mechanism. [Figure 9] This is a flowchart illustrating an example of the control procedure for Example 2. [Figure 10] This is a flowchart illustrating an example of the control procedure for Example 3. [Figure 11] This is a block diagram illustrating the schematic control configuration of the image forming apparatus in Example 4. [Modes for carrying out the invention]

[0009] The image forming apparatus according to the present invention will be described in more detail below with reference to the drawings.

[0010] [Example 1] <Overall configuration of the image forming apparatus> First, the overall configuration of the image forming apparatus of this embodiment will be described. Figure 1 is a schematic cross-sectional view showing the overall configuration of the image forming apparatus 200 of this embodiment. The image forming apparatus 200 of this embodiment is a laser printer that can form an image on a sheet-like recording material P using an electrophotographic method.

[0011] The image forming apparatus 200 has a photosensitive drum 201, which is a rotatable drum-shaped (cylindrical) photoreceptor (electrophotographic photoreceptor) that serves as an image carrier (image holder). The photosensitive drum 201 has a photosensitive layer formed on its surface and is driven to rotate in the direction of arrow R1 (clockwise) in the figure by a driving force transmitted from a drive unit 231 (Figure 2) which serves as a driving means. The surface of the rotating photosensitive drum 201 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charging roller 202, which is a roller-type charging member that serves as a charging means. During charging, a predetermined charging voltage (charging bias) is applied to the charging roller 202. The surface of the charged photosensitive drum 201 is scanned and exposed according to image information by an exposure device (laser scanner) 203 which serves as an exposure means, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 201. The exposure device 203 irradiates the photosensitive drum 201 with laser light based on the image information generated by the control unit 100. The control unit 100 generates image information for image formation in the image forming apparatus 200 based on job information input from an external device 400 (Figure 2), such as a personal computer (PC). Job information can also be a print instruction and includes an instruction to start image formation, various setting information for image formation, and image information for the image to be formed. Furthermore, as will be described later, a job is a series of operations in which an image is formed (toner image is transferred) on one or more recording materials P in response to a single start instruction and output.

[0012] The electrostatic latent image formed on the photosensitive drum 201 is developed (visualized) by a developing device 227 that supplies toner as a developer, forming a toner image (toner image, developer image) on the photosensitive drum 201. A transfer roller 206, a roller-type transfer member acting as a transfer means, is positioned opposite the photosensitive drum 201. The transfer roller 206 is pressed toward the photosensitive drum 201, forming a transfer portion (transfer nip portion) Nt, which is the contact area between the photosensitive drum 201 and the transfer roller 206. In this embodiment, the transfer roller 206 rotates in conjunction with the rotation of the photosensitive drum 201. The transfer roller 206 supplies a transfer charge to the recording material P passing through the transfer portion Nt. The toner image formed on the photosensitive drum 201 is transferred in the transfer portion Nt onto the recording material P, which is held and transported between the photosensitive drum 201 and the transfer roller 206. During transfer, a predetermined transfer voltage (transfer bias) is applied to the transfer roller 206. Recording material (recording medium, transfer material, sheet) P, such as paper or plastic sheets, is stored in a cassette 215 which serves as a feeding unit. The recording material P stored in the cassette 215 is fed out one sheet at a time from the cassette 215 by feeding rollers 216 and other feeding components. This recording material P is then transported to the transfer unit Nt by transport rollers 217, 218 and other transport components in a manner that synchronizes with the toner image on the photosensitive drum 201.

[0013] The recording material P is transported from the photosensitive drum 201 to a fixing device (image heating fixing device) 207 as a fixing means, while the toner image is transferred from the drum 201. The fixing device 207 is composed of a fixing film 208, a pressure roller 209, a fixing heater 210, a stay 211, a reinforcing member 212, a thermistor 213, etc. The fixing film 208 is a cylindrical film whose longitudinal direction is the depth direction connecting the front and back sides of the paper surface in Figure 1. The pressure roller 209 is a roller that, when pressed against the fixing film 208, forms a fixing portion (fixing nip portion) Np, which is the contact portion between the fixing film 208 and the pressure roller 209. The pressure roller 209 is rotationally driven by a driving force transmitted from the drive unit 231 (Figure 2) as a driving means, and the fixing film 208 rotates in accordance with the rotation of the pressure roller 209. The fixing heater 210 is a heating element that comprises, for example, a ceramic substrate, a heating layer and a protective layer. The stay 211 is a member for holding the fuser heater 210. The reinforcing member 212 is a reinforcing member for the stay 211 and other components. The thermistor 213 is a temperature sensing means for detecting the temperature of the fuser heater 210. The fuser heater 210 is connected in series with an over-temperature protection element, such as a thermal fuse (not shown), and a power supply drive unit. The fuser device 207 heats the recording material P passing through the fuser unit Np by heating the fuser heater 210, thereby fixing (melting and solidifying) the toner image on the recording material P.

[0014] The recording material P on which the toner image has been fixed is discharged (output) via the discharge port 205 to the discharge section 214 located at the top of the image forming apparatus 200 by transport rollers 219, 220, etc., which serve as transport members.

[0015] <Developing equipment> Next, the configuration of the developing apparatus 227 in this embodiment will be described. The developing apparatus 227 is composed of a developing container 221, a developing roller 204 as a developer carrier (developing member), a supply roller 222 as a developer supply member, and the like.

[0016] The developing container 221 contains toner t as a developer. In this embodiment, the developing device 227 uses a non-magnetic one-component developer composed of a heat-softening resin or the like as the developer. The inside of the developing container 221 is divided into a toner chamber 221a and a developing chamber 221b by a partition wall 221c, and the inside of the toner chamber 221a and the inside of the developing chamber 221b are in communication through a communication port 221d provided in the partition wall 221c. The toner t contained in the toner chamber 221a is supplied to the developing chamber 221b through the communication port 221d. The rotating shaft 223 and other rotating members provided in the toner chamber 221a will be described later in relation to the toner amount detection means.

[0017] An opening is provided in the developing chamber 221b opposite the photosensitive drum 201, and a developing roller 204 is positioned so that a portion of it is exposed to the outside of the developing chamber 221b through this opening. A supply roller 222 is also positioned inside the developing chamber 221b so as to contact the developing roller 204. In this embodiment, during development, the developing roller 204 is brought into contact with the photosensitive drum 201. The developing roller 204 is driven by a driving force transmitted from the drive unit 231 (Figure 2), which acts as a driving means, and is rotationally driven so that the surface of the developing roller 204 and the surface of the photosensitive drum 201 move in the forward direction at the contact point (developing section) with the photosensitive drum 201. The supply roller 222 is also driven by a driving force transmitted from the drive unit 231 (Figure 2), which acts as a driving means, and is rotationally driven so that, for example, the surface of the developing roller 204 and the surface of the supply roller 222 move in opposite directions at the contact point between the developing roller 204 and the supply roller 222. Furthermore, the rotation axis direction of the photosensitive drum 201 and the rotation axis direction of the developing roller 204 are approximately parallel, and the rotation axis direction of the developing roller 204 and the rotation axis direction of the supply roller 222 are approximately parallel.

[0018] The toner t contained in the developing chamber 221b is supplied onto the developing roller 204 by the supply roller 222 and carried on the developing roller 204. The toner t carried and transported on the developing roller 204 moves from the developing roller 204 to the photosensitive drum 201 in accordance with the electrostatic latent image formed on the photosensitive drum 201, and adheres to the photosensitive drum 201. This forms a toner image on the photosensitive drum 201. During development, a predetermined development voltage (development bias) is applied to the developing roller 204. In this embodiment, toner t charged to a normal polarity, which is the same polarity as the charge polarity of the photosensitive drum 201 (negative polarity in this embodiment), adheres to the exposed area on the photosensitive drum 201, where the absolute value of the potential has decreased after being uniformly charged and then exposed.

[0019] In this embodiment, the toner container 228 is detachably attached to the developing container 221. The toner container 228 and the developing container 221 are configured such that when the toner container 228 is attached to the developing container 221, the inside of the toner container 228 and the inside of the toner chamber 221a of the developing container 221 are in communication. Based on the detection result by the toner amount detection means described later, for example, if the amount of toner inside the toner chamber 221a falls below a predetermined amount, the toner container 228 is replaced with a new toner container 228. Then, toner is supplied to the developing container 221 (toner chamber 221a) from this new toner container 228.

[0020] Furthermore, the toner container 228 may remain attached to the developing container 221 while image formation is performed. In this case, toner may be supplied from the toner container 228 to the developing container 221 all at once, or it may be supplied sequentially according to the toner consumed from the developing container 221. Alternatively, the toner container 228 may be removed from the developing container 221 after toner has been supplied from the toner container 228 but before image formation begins.

[0021] <Control Configuration> Next, the control configuration of the image forming apparatus 200 in this embodiment will be described. Figure 2 is a block diagram illustrating the schematic control configuration of the image forming apparatus 200 in this embodiment. The image forming apparatus 200 is equipped with a control unit 100 as a control means for controlling the operation of the image forming apparatus 200. The control unit 100 is composed of a CPU 110 as an arithmetic processing means (arithmetic processing unit) which is the central element for performing arithmetic processing, a memory (storage medium) 120 which is composed of RAM, ROM and non-volatile memory as storage means (storage unit), and an input / output circuit (not shown) for inputting and outputting signals between the control unit 100 and external devices. The ROM stores a control program, a pre-determined data table, etc. The RAM, which is a rewritable memory, stores information input to the control unit 100, detected information, calculation results, etc. The non-volatile memory stores various setting information, various usage history information, etc. The CPU 110 and the memory 120 can transfer and read data from each other.

[0022] The control unit 100 is connected to various parts of the image forming apparatus 200. For example, the control unit 100 is connected to a drive unit 231 that drives the photosensitive drum 201, the rotating body of the developing device 227 (developing roller 204, supply roller 222, and the rotating shaft 223 described later), and the pressure roller 209 of the fixing device 207. The drive unit 231 may have separate drive sources for driving the objects to be driven, such as the photosensitive drum 201, the developing device 227, and the fixing device 207, or it may have a common drive source for driving some (or all) of the objects to be driven. In this embodiment, the image forming apparatus 200 is configured so that driving force is transmitted from a common drive source of the drive unit 231 to the photosensitive drum 201 and the rotating body of the developing device 227 (developing roller 204, supply roller 222, and the rotating shaft 223 described later).

[0023] Furthermore, an exposure device 203 is connected to the control unit 100. Also connected to the control unit 100 is a high-voltage power supply unit 232 that applies the charging voltage, developing voltage, and transfer voltage to the charging roller 202, developing roller 204, and transfer roller 206, respectively. The high-voltage power supply unit 232 may have separate power supplies that generate the voltages applied to the target objects such as the charging roller 202, developing roller 204, and transfer roller 206, or a power supply that generates the voltages applied to several target objects may be shared.

[0024] Furthermore, the control unit 100 is connected to an operation unit 233 provided on the image forming apparatus 200. The operation unit 233 has a display unit such as a liquid crystal panel as a display means for displaying information to an operator such as a user or service staff (here, simply referred to as "user") based on control by the control unit 100. The operation unit 233 also has an input unit such as a key as an input means for inputting information to the control unit 100 based on user operations. The operation unit 233 may be configured to have a touch panel that has the functions of both a display unit and an input unit. In addition, a magnetic flux detection unit 226, which will be described later, is connected to the control unit 100. Furthermore, an external device 400 is connected to the control unit 100. The external device 400 is an information device such as a personal computer (PC) for the user to instruct the image forming apparatus 200 to input job information.

[0025] The control unit 100 can comprehensively control each part of the image forming apparatus 200 based on job information input from the external device 400, thereby causing the image forming apparatus 200 to perform image forming. The control unit 100 can also control the execution of a process to detect the amount of toner using a toner amount detection means, which will be described later. Furthermore, the control unit 100 can control the execution of a process to notify the amount of toner based on the results of the toner amount detection process.

[0026] The image forming apparatus 200 executes a job (print job, printing operation), which is a series of operations that form an image (transfer toner image) on one or more recording materials P in response to a single start instruction and output it. A job generally has an image forming process, a pre-rotation process, a paper-to-paper process when forming an image on multiple recording materials P, and a post-rotation process. The image forming process (during image forming) is the period during which the electrostatic image of the image to be actually formed on the recording material P and output is formed, the toner image is formed, and the toner image is transferred. More specifically, the timing of the image forming process differs depending on the position where each of these processes—electrostatic image formation, toner image formation, and toner image transfer—is performed. The pre-rotation process (during pre-rotation) is the period during which preparatory operations are performed before the image forming process, from when a start instruction is input until the image is actually formed. The paper-to-paper process (during paper-to-paper) is the period corresponding to the time between recording materials P when image forming on multiple recording materials P is performed continuously (continuous image forming). The post-rotation process (post-rotation period) is the period during which tidying operations (preparation operations) are performed after the image formation process. The pre-rotation process, paper-to-paper process, and post-rotation process can also be referred to as the non-image formation period. In this embodiment, the period from when the job operation starts until the photosensitive drum 201 (and the rotating shaft 223 described later) rotates at the speed of the image formation process is sometimes referred to as the "image formation operation period." This image formation operation period is typically the period from when the formation (development) of the first image of the job starts until the formation (development) of the last image of the job is completed, and may include the image formation process and the paper-to-paper process described above.

[0027] <Toner quantity detection means> Next, the toner quantity detection means in this embodiment will be described. Figure 3 is a schematic cross-sectional view of the developing apparatus 227 for illustrating the toner quantity detection means in this embodiment, with Figures 3(a) and 3(b) showing different toner quantities inside the developing container 221. Figure 4 is a schematic perspective view showing the rotating shaft 223 and other components that constitute the toner quantity detection mechanism 300 as the toner quantity detection means in this embodiment.

[0028] In this embodiment, the toner detected by the toner quantity detection means is the toner t stored inside the developing container 221, particularly the toner chamber 221a. In this embodiment, the toner quantity detection means also detects the remaining toner amount, which is the amount of unused toner t remaining inside the developing container 221, particularly the toner chamber 221a.

[0029] A rotating shaft 223 is provided as a rotating member inside the toner chamber 221a of the developing container 221. The rotating shaft 223 is driven to rotate in the direction of arrow R2 (clockwise direction) in the figure by a driving force transmitted from the drive unit 231 (Figure 2), which is a driving means. The rotation axis direction of the rotating shaft 223 is approximately parallel to the rotation axis direction of the developing roller 204 (photosensitive drum 201, supply roller 222).

[0030] As shown in Figure 4, a toner stirring member 229 is attached to the rotating shaft 223 (the toner stirring member 229 is not shown in Figure 3). The toner stirring member 229 is composed of a blade-shaped member made of, for example, a flexible sheet-like material. The longitudinal direction of the toner stirring member 229 is aligned with the rotation axis direction of the rotating shaft 223, and the short direction, which is substantially perpendicular to this longitudinal direction, is aligned with the rotational radius direction of the rotating shaft 223. One end of the toner stirring member 229 in the short direction is fixed to the rotating shaft 223 along the longitudinal direction. When the rotating shaft 223 rotates, the toner stirring member 229 rotates within the toner chamber 221a, and the toner inside the developing container 221, in particular the toner inside the toner chamber 221a, is stirred by the toner stirring member 229.

[0031] Furthermore, a retaining member 225 for holding the magnet 224 on the rotating shaft 223 is attached to the rotating shaft 223. The retaining member 225 is composed of a strip-shaped member formed of, for example, a flexible sheet-like material. The longitudinal direction of this retaining member 225 is aligned with the rotational radius direction of the rotating shaft 223, and the short direction, which is substantially perpendicular to this longitudinal direction, is aligned with the rotational axis direction of the rotating shaft 223. One end of the retaining member 225 in the longitudinal direction is fixed (connected) to the rotating shaft 223, and a magnet (permanent magnet) 224 as a magnetic material is attached to the other end. In this embodiment, the retaining member 225 is attached to the rotating shaft 223 so as to be located substantially in the center in the longitudinal direction of the developing container 221 along the rotational axis direction of the rotating shaft 223. When the rotating shaft 223 rotates, the holding member 225 and the magnet 224 attached thereto rotate within the toner chamber 221a, making it possible to detect the remaining amount of toner inside the developing container 221, particularly the toner chamber 221a, as will be described later.

[0032] Thus, in this embodiment, the rotating shaft 223 has the function of rotating the magnet 224 and the function of agitating the toner inside the developing container 221, particularly the toner chamber 221a. The holding member 225 is connected to the rotating shaft 223 and moves (rotates) inside the developing container 221 (toner chamber 221a) as the rotating shaft 223 rotates. The magnet 224 is held by the holding member 225 and moves (rotates) inside the developing container 221 (toner chamber 221a) as the rotating shaft 223 rotates. The toner agitator 229 is also connected to the rotating shaft 223 and agitates the toner inside the developing container 221 (toner chamber 221a) as the rotating shaft 223 rotates.

[0033] As described above, in this embodiment, the toner whose quantity is detected by the toner quantity detection means is specifically the toner located inside the toner chamber 221a of the developing container 221. However, in the following description, the toner whose quantity is detected may be described simply as the toner located inside the developing container 221.

[0034] On the other hand, a magnetic flux detection unit 226 is provided on the outside of the developing container 221. The magnetic flux detection unit 226 is a detection unit provided at a predetermined position on the developing container 221, and is an example of a detection unit that outputs a signal corresponding to the distance between the magnetic member (magnet) 224 and the detection unit based on the action of magnetism. In this embodiment, the output of the magnetic flux detection unit 226 is configured to change according to the magnetic flux density of the magnetic flux passing through the magnetic flux detection unit 226. In this embodiment, the magnetic flux detection unit 226 is fixed to the outer wall of the developing container 221 which constitutes the wall of the toner chamber 221a. Furthermore, the magnetic flux detection unit 226 is provided on the developing container 221 so as to be located approximately in the center in the longitudinal direction of the developing container 221, corresponding to the position of the magnet 224 in the longitudinal direction of the developing container 221. The control unit 100 has a function to calculate the remaining amount of toner inside the developing container 221 based on the output signal of the magnetic flux detection unit 226. In other words, the CPU 110 of the control unit 100 can function as a toner remaining amount calculation control unit that calculates the remaining amount of toner inside the developing container 221. Based on the calculation result of the remaining toner amount, the control unit 100 can notify the user of the remaining toner amount by displaying information about the remaining toner amount on, for example, the display unit of the operation unit 233 or the display unit of the external device 400. This allows the control unit 100 to prompt the user to replace the toner container 228 that supplies toner to the developing container 221. The control unit 100 may also, for example, notify the user of a warning indicating that the toner container 228 needs to be replaced when the remaining amount of toner inside the developing container 221 falls below a predetermined value.

[0035] In this embodiment, a toner quantity detection mechanism 300 is configured as a toner quantity detection means, comprising a rotating shaft 223, a magnet 224, a holding member 225, a magnetic flux detection unit 226, and the like.

[0036] Figures 3(a) and 3(b) show the rotational trajectories of the magnet 224 according to the amount of toner t (remaining toner) inside the developing container 221, respectively. As shown in Figure 3(a), when the amount of toner remaining inside the developing container 221 is small, the magnet 224 follows a rotational trajectory like trajectory 301 when the rotation axis 223 is rotated. On the other hand, as shown in Figure 3(b), when the amount of toner remaining inside the developing container 221 is large, the magnet 224 follows a rotational trajectory like trajectory 302, which is different from trajectory 301, due to the rotational resistance of the toner t when the rotation axis 223 is rotated. In other words, when viewed along the rotation axis direction of the rotation axis 223, the rotational radius of the magnet 224 is the first radius when the amount of toner inside the developing container 221 is the first amount, and the rotational radius of the magnet 224 is the second radius, which is larger than the first radius, when the amount of toner inside the developing container 221 is the second amount, which is less than the first amount. In other words, the shortest distance between the magnet 224 and the magnetic flux detection unit 226 while the rotating shaft 223 is rotating is the first distance when the amount of toner inside the developing container 221 is the first amount, and the second distance which is shorter than the first distance when the amount of toner inside the developing container 221 is the second amount which is less than the first amount. In the state shown in Figure 3(b), the rotational resistance due to the toner t is greater than in the state shown in Figure 3(a), so the holding member 225 deforms to bend in the opposite direction to the rotation of the rotating shaft 223.

[0037] In this embodiment, the magnetic flux detection unit 226 outputs a High level (also simply referred to as "H") when the magnetic flux density of the magnetic flux 303 passing through the magnetic flux detection unit 226 is less than a predetermined value. In this embodiment, the magnetic flux detection unit 226 outputs a Low level (also simply referred to as "L") when the magnetic flux density of the magnetic flux 303 passing through the magnetic flux detection unit 226 is equal to or greater than the predetermined value.

[0038] In this embodiment, the toner remaining amount is defined as 100% when the maximum amount of toner is filled inside the developing container 221. The maximum amount of toner is filled inside the developing container 221, which typically refers to the case when the developing device 227 is in a new condition or immediately after toner has been replenished from the toner container 228 to the developing container 221. In this embodiment, the toner remaining amount is defined as 0% when the toner inside the toner chamber 221a of the developing container 221 is substantially depleted (a state in which toner is substantially present only in the developing chamber 221b of the developing container 221). In this embodiment, the developing device 227 is configured such that the magnetic flux detection unit 226 outputs an L level for at least a portion of the time during which the magnet 224 passes near the magnetic flux detection unit 226 (including the nearest point) as it rotates from 100% to 0% toner remaining.

[0039] Based on the relationship between the radius of rotation of the magnet 224 (the distance between the magnet 224 and the magnetic flux detection unit 226) as described above, when the amount of toner inside the developing container 221 is a first amount, the time it takes for the magnetic flux detection unit 226 to output an L level during one rotation of the magnet 224 is a first time. When the amount of toner inside the developing container 221 is a second amount, which is less than the first amount, the time it takes for the magnetic flux detection unit 226 to output an L level during one rotation of the magnet 224 is a second time, which is longer than the first time. In other words, when the magnet 224 follows the trajectory 301 shown in Figure 3(a), the period (time) during which the magnet 224 passes near the magnetic flux detection unit 226 per rotation of the rotation axis 223 is longer than when the magnet 224 follows the trajectory 302 shown in Figure 3(b). Therefore, the less toner remains inside the developing container 221, the longer the L output period of the magnetic flux detection unit 226 per rotation of the rotating shaft 223 (also referred to here as "L output period / rotation").

[0040] In other words, in this embodiment, the magnetic flux detection unit 226 outputs a first signal (L) if the magnetic flux density of the magnetic flux passing through the magnetic flux detection unit 226 is greater than or equal to a predetermined value, and outputs a second signal (H) different from the first signal if the magnetic flux density is less than the predetermined value. The control unit 100 can then acquire toner amount information based on the time the magnetic flux detection unit 226 outputs the first signal (L) for each rotation of the rotating shaft 223. In this way, the distance between the magnet and the detection unit can be determined (detected) and the remaining toner amount can be calculated using a detection unit with a relatively inexpensive configuration that switches output when a magnetic flux with a magnetic flux density of greater than or equal to a predetermined value passes through the detection unit.

[0041] Figure 5 shows the remaining toner amount T inside the developing container 221 at each rotational speed of the rotating shaft 223 in this embodiment. n This graph shows the average measurement results of the relationship between the L output period / rotation of the magnetic flux detection unit 226 and the remaining toner T. n The graph shows the percentage [%], and the vertical axis shows the L output period / rotation [msec]. As described above, the remaining toner T when the maximum amount of toner is filled inside the developing container 221. n This is set to 100%. In Figure 5, the 1 / 1 speed plotted as a square (■) is the rotational speed of the rotating shaft 223 when the image forming speed of the image forming apparatus 200 in this embodiment is set to the fastest setting. The 1 / 2 speed plotted as a triangle (▲) is the rotational speed of the rotating shaft 223 that is 1 / 2 when the rotational speed of 1 / 1 speed is used as a reference. The 1 / 3 speed plotted as a circle (●) is the rotational speed of the rotating shaft 223 that is 1 / 3 when the rotational speed of 1 / 1 speed is used as a reference.

[0042] In this embodiment, the image forming speed of the image forming apparatus 200 is represented by the rotation speed (e.g., circumferential speed) of the photosensitive drum 201. Therefore, the image forming speed can be paraphrased as the driving speed of the photosensitive drum 201. Further, the rotation speed of the rotation shaft 223 can be expressed, for example, in revolutions per minute (rpm). In this embodiment, driving force is transmitted from a common drive source of the drive unit 231 to the photosensitive drum 201 and the rotating bodies of the developing device 227 (developing roller 204, supply roller 222, and rotation shaft 223 described later). And in this embodiment, when the driving speed (image forming speed) of the photosensitive drum 201 changes, the rotation speeds of the rotating bodies of the developing device 227 (developing roller 204, supply roller 222, and rotation shaft 223 described later) also change in conjunction. That is, when the driving speed of the photosensitive drum 201 is the first driving speed, the rotation shaft 223 rotates at the first rotation speed, and when the driving speed of the photosensitive drum 201 is the second driving speed slower than the first driving speed, the rotation shaft 223 rotates at the second rotation speed slower than the first rotation speed.

[0043] From FIG. 5, in this embodiment, it can be seen that for all three types of rotation speeds of the rotation shaft 223, the toner remaining amount T n is the arrangement and configuration of the magnetic flux detection unit 226 that particularly has sensitivity around 40%. Also, when the toner remaining amount T n is small, the magnet 224 follows a rotation locus close to the locus 301 shown in FIG. 3(a), so that the time during which the magnetic flux density of the magnetic flux 303 passing through the magnetic flux detection unit 226 becomes a predetermined value or more becomes longer. And, for example, at a rotation speed of 1 / 1 speed and a toner remaining amount T n of 10% to 20%, the L output period / rotation is about 380 msec. Conversely, when the toner remaining amount T n is large, the magnet 224 follows a rotation locus close to the locus 302 shown in FIG. 3(b), so that the time during which the magnetic flux density of the magnetic flux 303 passing through the magnetic flux detection unit 226 becomes a predetermined value or more becomes shorter. And, for example, at a rotation speed of 1 / 1 speed and a toner remaining amount T n of 80% to 100%, the L output period / rotation is about 200 msec.

[0044] Also, from FIG. 5, for all three types of rotation speeds of the rotation shaft 223, the toner remaining amount T nIt can be seen that the smaller the value, the longer the L output period / rotation. For example, if the L output period / rotation of the magnetic flux detection unit 226 is about 250 msec at 1 / 1 speed, the remaining toner T n It can be seen that it is about 50% to 60%. The control unit 100 then checks the remaining toner amount T that was previously detected and stored in the memory 120 (for example, non-volatile memory). n-1 The information detected this time is the toner level T n Update with the information. Also, the next toner level T n+1 Until detection occurs, memory 120 (e.g., non-volatile memory) will display the updated toner level T. n The latest toner level T n It is stored as such. The control unit 100 then displays the latest toner remaining amount T on the display unit of the operation unit 233 or the display unit of the external device 400, for example. n This can be communicated to the user.

[0045] Here, by configuring the rotating member to combine the functions of rotating the magnet and stirring the toner inside the container, it becomes easier to miniaturize the image forming apparatus. For example, in such a configuration where the rotating member combines the functions of rotating the magnet and stirring the toner, as the image forming speed of the image forming apparatus increases, the toner stirring speed also increases, and the rotation speed of the rotating member that rotates the magnet also increases. When the rotation speed of the rotating member increases, the centrifugal force applied to the magnet increases, making it easier for the magnet to approach the magnetic flux detection unit. As a result, the difference in distance between the magnet and the magnetic flux detection unit when the toner level is low and when it is high tends to decrease. When the change in magnetic flux density of the magnetic flux passing through the magnetic flux detection unit in response to changes in the toner level is defined as the change sensitivity, the increase in centrifugal force mentioned above means a decrease in the change sensitivity. In other words, when the image forming speed of the image forming apparatus at its fastest setting increases, the change sensitivity decreases in detecting the toner level at the fastest setting, which tends to decrease the accuracy of toner level detection.

[0046] In this embodiment, the image carrier and the rotating member are driven by a common drive source, and when the driving speed (image formation speed) of the image carrier changes, the rotation speed of the rotating member also changes in conjunction. However, even in configurations where these drive sources are provided separately and do not operate in conjunction, similar problems may arise, for example, when increasing the toner stirring speed to accommodate the increased image formation speed. Furthermore, similar problems may arise not only in configurations where the rotating member combines the functions of rotating a magnet and stirring toner, but also in configurations where the drive source is shared between the image carrier and the rotating member, and they rotate in conjunction.

[0047] Figure 6 shows the remaining toner amount T inside the developing container 221 at each rotational speed of the rotating shaft 223 in this embodiment. n This is a graph showing the relationship between the L output period change rate dt / d% of the magnetic flux detection unit 226 and the remaining toner amount T. n The vertical axis represents the remaining toner amount (T). n Decrease (ΔToner level T) n This shows the rate of change dt / d% (here also simply called "rate of change of L output period") of the magnetic flux detection unit 226 for the L output period / rotation [msec] of [%]). In Figure 6, the square (■) and dashed line plots represent the case of 1 / 1 speed, the triangle (▲) and dashed line plots represent the case of 1 / 2 speed, and the circle (●) and solid line plots represent the case of 1 / 3 speed.

[0048] Figure 6 shows that as the rotational speed of the rotating shaft 223 decreases, the rate of change of the L output period tends to increase due to the decrease in centrifugal force applied to the magnet 224. In other words, the toner remaining amount T at 1 / 1 speed n The rate of change in L output period at around 30% and 50% is approximately 1.5 and 0.6, respectively. In contrast, the toner remaining T at 1 / 3 speed n The percentage change in L output period at around 30% and 50% is approximately 14.0 and 7.3, respectively. Also, the toner remaining amount at 1 / 2 speed T n The rate of change in L output period at around 30% and 50% is approximately 1.5 and 4.0, respectively. Thus, for example, the toner remaining amount T nThe rate of change in the L output period at around 30% and 50% increases by approximately 9 times and 12 times, respectively, at 1 / 3 speed compared to 1 / 1 speed. And the remaining toner T at 1 / 3 speed n The relationship between the L output period change rate and the remaining toner T n It can be seen that the peak is centered around 40%, with a wider base than in the case of 1 / 1 speed. In other words, in the case of 1 / 3 speed, the toner level T is higher than in the case of 1 / 1 speed. n The toner level is around the 20% to 60% range. n Sensitivity to changes has improved, and the detection range has expanded.

[0049] In this embodiment, the first toner quantity information (first information), which is toner quantity information regarding the amount of toner inside the developing container 221 acquired based on the output of the magnetic flux detection unit 225 when the rotating shaft 223 is rotating at a first rotational speed, is updated (update process) with the second toner quantity information (second information), which is acquired based on the output of the magnetic flux detection unit 225 when the rotating shaft 223 is rotating at a second rotational speed slower than the first rotational speed. In this embodiment, the first toner quantity information is acquired during the image formation operation of the job, which is the first period including the development period. In this embodiment, the second toner quantity information is acquired during the post-rotation of the job, which is the second period not including the development period. In this embodiment, the first toner quantity information acquired during the image formation operation and stored in the memory 120 is updated by storing the second toner quantity information acquired during the post-rotation in the memory 120. In this embodiment, the second toner quantity information is overwritten with the first toner quantity information and stored in the memory 120 (the first toner quantity information is rewritten with the second toner quantity information). The second toner quantity information is then used as the latest toner quantity information regarding the amount of toner inside the developing container 221 for processing such as toner quantity notification. This effectively corrects (corrects) the toner quantity information regarding the amount of toner inside the developing container 221. Here, the operation of acquiring the first toner quantity information when the rotating shaft 223 is rotating at the first rotational speed and storing it in the memory 120 is also called the "high-speed detection operation". Furthermore, the operation of acquiring the second toner quantity information when the rotating shaft 223 is rotating at the second rotational speed and storing the second toner quantity information in the memory 120 so as to update the first toner quantity information stored in the memory 120 with the second toner quantity information is also called the "low-speed detection operation".

[0050] As a result, according to this embodiment, even if the first rotation speed is increased in conjunction with the increased image forming speed of the image forming apparatus 200, a decrease in the detection accuracy of the toner amount (remaining toner) can be suppressed. According to this embodiment, for example, during continuous printing of a large number of prints, although the detection accuracy is lower than that of the low-speed detection operation, information regarding the amount of toner inside the developing container 221 and its changes can be obtained by the high-speed detection operation. After printing is completed, more accurate information regarding the amount of toner inside the developing container 221 can be obtained by the low-speed detection operation.

[0051] <Control Procedure> Next, the procedure for detecting the remaining toner amount in this embodiment will be described. Figure 7 shows the toner amount T when the image forming apparatus 200 executes a job in this embodiment. n This flowchart illustrates an example of the procedure for detecting [the specified condition]. Here, we take the example of a case where the user instructs the external device 400 to input information about a job with multiple pages and the fastest image formation speed setting to the image forming apparatus 200. The number of pages for image formation (number of printed pages) can be represented by the number of surfaces of the recording material P to which the toner image formed on the photosensitive drum 201 is transferred.

[0052] When job information (print instruction) is input to the control unit 100 (S101), it controls the system to start image formation at the first drive speed (fastest setting) (S102). At this time, the rotating shaft 223 rotates at the first rotational speed (1 / 1 speed). In this embodiment, the rotating shaft 223 rotates multiple times during image formation (more specifically, during development) per page. Based on the moving average value of the L output period / rotation of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the first rotational speed, the control unit 100 determines the remaining toner amount T inside the developing container 221 when the rotating shaft 223 is rotating at the first rotational speed. act The control unit 100 determines (detects) the toner level T based on information (table data, etc.) showing the relationship between the output period / rotation and the remaining toner level, as shown in Figure 5, which has been obtained in advance and stored in the memory 120 (for example, ROM). actThe control unit 100 can determine the remaining toner amount T obtained in S103. act The current toner level inside the developing container 221 is T n The toner level T is updated and stored in memory 120 (for example, non-volatile memory) (S104). The control unit 100 also updates the toner level T as needed. n The control unit 100 can inform the user of the latest toner level T based on the user's operation on the operation unit 233 or the external device 400. n It can also notify the toner level T. n Each time it is updated, the latest toner level T is displayed on the display unit of the operation unit 233 and the display unit of the external device 400. n It can also notify the latest toner level T. n It can be reported.

[0053] Next, after the image formation of the current page is completed (S105), the control unit 100 determines whether or not the image formation of the next page will be performed consecutively (S106). If the control unit 100 determines in S106 that the image formation of the next page will be performed consecutively, it returns to the process in S103. On the other hand, if the control unit 100 determines in S106 that the image formation of the next page will not be performed consecutively (that the current page was the last page of the job), it controls the rotation speed of the rotating shaft 223 to be changed to a second rotation speed (1 / 3 speed in this embodiment), which is slower than the first rotation speed, during the subsequent rotation (S107). In this embodiment, the control unit 100 controls the rotation speed of the rotating shaft 223 to be changed from the first rotation speed (1 / 1 speed) to the second rotation speed (1 / 3 speed) by changing the drive speed of the photosensitive drum 201 to a second drive speed, which is slower than the first drive speed (fastest setting). Then, the control unit 100 determines the remaining toner amount T inside the developing container 221 when the rotating shaft 223 is rotating at the second rotational speed, based on the L output period / rotation of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the second rotational speed. actThe control unit 100 determines (detects) the remaining toner amount (S108). Similarly, the control unit 100 determines the remaining toner amount T based on information (table data, etc.) that shows the relationship between the L output period / rotation and the remaining toner amount, as shown in Figure 5, which has been obtained in advance and stored in the memory 120 (for example, ROM). act The control unit 100 can determine the remaining toner amount T inside the developing container 221 when the rotating shaft 223 is rotating at the second rotational speed, based on the average value of the L output period / rotation of the magnetic flux detection unit 226 acquired while the rotating shaft 223 rotates multiple times. act The control unit 100 can determine the remaining toner amount T obtained in S108. act The current toner level inside the developing container 221 is T n The data is then updated and stored in memory 120 (for example, non-volatile memory) (S109). After that, the control unit 100 controls the operation of the job to terminate (S110).

[0054] For example, the toner level T before the job starts. n The percentage is 57%, and the L output period / rotation of the magnetic flux detection unit 226 when the rotation axis 223 is rotating at the first rotation speed during the image formation operation of the job is consistently about 250 msec. In this case, the remaining toner amount T determined by the control unit 100 during the image formation operation is n This does not change much from 57%. Subsequently, for example, when the L output period / rotation of the magnetic flux detection unit 226 is about 640 msec when the rotating shaft 223 is rotating at the second rotational speed during the reverse rotation, the control unit 100 will determine the remaining toner T n The control unit 100 determines that the remaining toner is 57% and stores it in memory 120. On the other hand, for example, when the rotating shaft 223 is rotating at the second rotational speed during the reverse rotation, if the L output period / rotation of the magnetic flux detection unit 226 is about 700 msec, the control unit 100 determines the remaining toner T n The control unit determines that the remaining toner amount is 48% and stores it in memory 120. In other words, according to this embodiment, the control unit 100 determines a more accurate remaining toner amount T n This can be determined and stored in memory 120.

[0055] In this embodiment, the rotation axis 223 rotates multiple times during image formation (more specifically, during development) per page, but it may rotate only once. Based on the output of the magnetic flux detection unit 226 when the rotation axis 223 has rotated at least once, the control unit 100 determines the remaining toner amount T n This can be determined. Furthermore, the image formation process for each page may include, for example, the time between pages (or between pages).

[0056] Furthermore, in this embodiment, the remaining toner amount T during the image forming operation is act This was determined based on the moving average value of the L output period / turn, but it may also be determined based on a representative value, such as the most recent value of the L output period / turn.

[0057] In this embodiment, a flexible sheet-like member was used as the holding member 225 for holding the magnet 224 on the rotating shaft 223. However, the present invention is not limited to this configuration. Any configuration is acceptable in which the rotational trajectory (the rotational radius of the magnet 224, or the distance between the magnet 224 and the magnetic flux detection unit 226) changes according to the amount of toner inside the developing container 221 when the magnet 224 is rotated by the rotating shaft 223. Figure 8 is a schematic cross-sectional view showing one modified example of the developing device 227 (elements having the same or corresponding configuration or function as those in this embodiment are denoted by the same reference numerals). Figures 8(a) and 8(b) show different states with different amounts of toner remaining inside the developing container 221. In the modified example shown in Figure 8, one end of the holding member 603 is rotatably connected to the rotating shaft 602 via the rotating shaft portion 601, and the magnet 224 is attached to the other end. As shown in Figure 8(a), when there is a large amount of toner remaining inside the developing container 221, the rotational trajectory of the magnet 224 when it is rotated by the rotating shaft 602 is as shown in trajectory 605. On the other hand, as shown in Figure 8(b), when there is a small amount of toner remaining inside the developing container 221, the rotational trajectory of the magnet 224 when it is rotated by the rotating shaft 602 is as shown in trajectory 606, and the distance between the magnet 224 and the magnetic flux detection unit 226 becomes closer than in the case of trajectory 605. This is because, in the state shown in Figure 8(a), the rotational resistance due to the toner is greater compared to the state shown in Figure 8(b), causing the holding member 603 to rotate in the opposite direction to the rotational direction of the rotating shaft 602 with the rotating shaft portion 601 as the pivot point.

[0058] Furthermore, the image forming apparatus 200 may be capable of image formation at multiple different image forming speeds, such as a first drive speed (fastest setting) and a second drive speed slower than the first drive speed. When the image forming apparatus 200 is capable of image formation at multiple image forming speeds, the image forming speed is set according to, for example, the type of recording material P on which the image is formed in the job. Typically, from the viewpoint of how well the toner image adheres to the recording material P, if a recording material P with a large basis weight (thickness) (such as cardboard) is used, the image forming speed is slower than when a recording material P with a small basis weight (thickness) (such as plain paper) is used. In this case, when image formation of a job is performed at the first drive speed (fastest setting), the remaining toner can be detected by the control of this embodiment. When image formation of a job is performed at the second drive speed (for example, a drive speed at which the rotating shaft 223 rotates at 1 / 3 speed), the detection result of the remaining toner during the image forming operation is stored as the current toner remaining value, and the detection of the remaining toner during subsequent rotations (low-speed detection operation) can be omitted. However, the image forming apparatus 200 is not limited to being able to form images at multiple different image forming speeds, such as a first drive speed (fastest setting) and a second drive speed slower than the first drive speed. For example, the image forming apparatus 200 may be able to form images only at the first drive speed (the drive speed at which the rotating shaft 223 rotates at the first rotational speed), but may be able to be driven at the second drive speed (the drive speed at which the rotating shaft 223 rotates at the second rotational speed) for low-speed detection operation.

[0059] Furthermore, the operation of rotating the rotating shaft 223 at a second rotational speed to acquire second toner amount information (low-speed detection operation) is not limited to being performed during the subsequent rotation. For example, it may be performed during the preceding rotation as a period during which no development is performed, or by extending the inter-paper process.

[0060] As described above, according to this embodiment, in a configuration that includes a mechanism for detecting the amount of toner by utilizing the change in distance between a magnet 224 rotated by a rotating shaft 223 and a magnetic flux detection unit 226, it is possible to suppress a decrease in the accuracy of toner amount detection.

[0061] [Example 2] Next, other embodiments of the present invention will be described. The basic configuration of the image forming apparatus in this embodiment is the same as that of the image forming apparatus in Embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those in the image forming apparatus of Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed descriptions are omitted.

[0062] In Example 1, the case where the low-speed detection operation is performed after the image formation of each job instructed by the user is completed (during post-rotation) was described. On the other hand, as can be seen from Figure 6, by changing the rotation speed of the rotation axis 223, the rate of change of the L output period of the remaining toner T is particularly significantly improved. n The area may be limited. In the configuration of this embodiment, which yields the relationship shown in Figure 6, in particular, the remaining toner T n In areas where the toner level is 70% or higher, the effect of improving the accuracy of toner level detection is minimal. Therefore, the toner level T n The system can be configured to perform a low-speed detection operation when the toner level is within a predetermined range (when predetermined conditions are met). This reduces downtime, which is the time when the image forming apparatus 200 cannot perform image forming, while accurately detecting the remaining toner level T through the low-speed detection operation. n It is possible to make such a determination.

[0063] Figure 9 shows the toner level T when the image forming apparatus 200 executes a job in this embodiment. n This is a flowchart illustrating an example of the procedure for detecting [the specified condition]. Here, as in Example 1, we take the case where the user instructs the external device 400 to input information for a multi-page job with the fastest image forming speed setting to the image forming apparatus 200. In the control of this embodiment shown in Figure 9, the same steps as those used in the control of Example 1 explained using Figure 7 are given the same step numbers, and detailed explanations are omitted as appropriate.

[0064] When the control unit 100 receives job information (print instruction) (S101), it controls the system to start image formation at the first drive speed (fastest setting) (S102). Then, the control unit 100 determines the remaining toner amount T based on the L output period / revolution of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the first rotational speed. act Determine the remaining toner T n The latest toner remaining amount T stored in memory 120 (for example, non-volatile memory) is updated and stored (S103-S106). The loop of S103-S106 continues until the image formation of the last page of the job is completed. Then, after the image formation of the last page of the job is completed, the control unit 100 checks the latest toner remaining amount T stored in memory 120. n and toner level T n A predetermined threshold T thres Compare this with (S201). From Figure 6, in the configuration of this embodiment, the remaining toner amount T n It can be seen that the difference in the rate of change of L output period due to the difference in rotational speed of the rotating shaft 223 becomes particularly pronounced in the region of approximately 50% or less. Therefore, in this embodiment, for example, threshold T thres Set this threshold T to 50%. thres This information is pre-set and stored in memory 120 (for example, ROM). In this embodiment, in S201, the control unit 100 checks the latest toner remaining amount T stored in memory 120. n The control unit 100 determines whether the amount is below the above threshold (50% or less in this embodiment). In S201, the control unit 100 checks the latest toner remaining amount T stored in the memory 120. n If it is determined that the remaining toner amount exceeds 50%, the control unit will terminate the job operation without performing a slow-speed detection operation (S110). Meanwhile, in S201, the control unit 100 checks the latest remaining toner amount T stored in the memory 120. nIf it is determined that the amount is 50% or less, the process proceeds to S107 as in Example 1 to perform the low-speed detection operation. In other words, the control unit 100 controls the rotation speed of the rotating shaft 223 to change to a second rotation speed (1 / 3 speed in this embodiment) that is slower than the first rotation speed when the rotating shaft 223 is rotating at the second rotation speed, based on the L output period / rotation of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the second rotation speed. act The control unit 100 determines the remaining toner amount T obtained in S108. n The current toner level T n The data is then updated and stored in memory 120 (for example, non-volatile memory) (S109). After that, the control unit 100 controls the operation of the job to terminate (S110).

[0065] In this embodiment, the control unit 100 controls the remaining toner amount T n If the value is within a predetermined range (in this embodiment, the range is 0% to 50%), a more accurate toner level T will be detected. n The toner remaining amount T can be determined and stored in memory 120. In this embodiment, the control unit 100 determines the remaining amount T n If the value exceeds a predetermined value (50% in this embodiment), the low-speed detection operation is not performed, thereby reducing downtime.

[0066] Furthermore, the predetermined conditions for determining whether to perform the low-speed detection operation are not limited to the toner level being below a predetermined threshold. For example, the low-speed detection operation may be performed when the toner level is within a predetermined range (this predetermined range may be a single continuous range or a range divided into multiple sections).

[0067] As described above, this embodiment provides the same effects as in Example 1, while also reducing downtime caused by operations to detect the amount of toner.

[0068] [Example 3] Next, other embodiments of the present invention will be described. The basic configuration of the image forming apparatus in this embodiment is the same as that of the image forming apparatus in Embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those in the image forming apparatus of Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed descriptions are omitted.

[0069] Example 1 describes the case where the low-speed detection operation is performed after the image formation of each job instructed by the user is completed (during post-rotation). Example 2 describes the case where the toner level T n The article explained how downtime can be reduced by determining whether to perform a slow detection operation accordingly. On the other hand, the amount of toner consumed per page in a typical job is sufficiently small compared to the amount of toner that can be stored inside the developing container 221. For example, after printing several tens of pages, the remaining toner level T is not reached. n This can result in a decrease of 1%. In this case, the toner level after printing several pages is T n It can be difficult to accurately detect changes in the toner level. Therefore, the slow-speed detection operation can be performed every time a certain number of pages are printed (when the number of printed pages between slow-speed detection operations meets a predetermined condition). This reduces downtime while accurately detecting the remaining toner level through the slow-speed detection operation. n This allows for the determination of the remaining toner amount T. n The system is configured to perform a slow-speed detection operation when the specified value is within a predetermined range, and furthermore, to perform a slow-speed detection operation every time a certain number of pages or more are printed. This further reduces downtime.

[0070] Figure 10 shows the toner level T when the image forming apparatus 200 executes a job in this embodiment. nThis is a flowchart illustrating an example of the procedure for detecting [the specified condition]. Here, as in Examples 1 and 2, we take the example of a case where the user instructs the external device 400 to input information for a multi-page job with the fastest image forming speed setting to the image forming apparatus 200. In the control of this embodiment shown in Figure 10, the same steps as those used in the control of Example 1 explained using Figure 7 and the control of Example 2 explained using Figure 9 are given the same step numbers, and detailed explanations are omitted as appropriate.

[0071] When the control unit 100 receives job information (print instruction) (S101), it controls the system to start image formation at the first drive speed (differential speed setting) (S102). Then, the control unit 100 determines the remaining toner amount T based on the L output period / revolution of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the first rotational speed. act Determine the remaining toner T n The data is then updated and stored in memory 120 (e.g., non-volatile memory) (S103-S105). The control unit 100 also stores the cumulative number of printed pages during the low-speed detection operation (here, also simply referred to as "cumulative number of printed pages") stored in memory 120 (e.g., non-volatile memory) P n The value is incremented by 1 (S301), and the process proceeds to S106 (confirmation of completion of image formation of the job). The loop from S103 to S106 continues until image formation of the last page of the job is completed. Then, after image formation of the last page of the job is completed, the control unit 100 checks the latest toner remaining amount T stored in memory 120. n and toner level T n A predetermined threshold T thres (In this embodiment, 50%) is compared with (S201). In S201, the control unit 100 checks the latest toner remaining amount T stored in the memory 120. n If it is determined that the rate exceeds 50%, the system will terminate the job operation without performing the slow-speed detection operation (S110).

[0072] In S201, the control unit 100 checks the latest toner remaining amount T stored in the memory 120. nIf it is determined that it is 50% or less, the cumulative number of printed pages stored in the memory 120 and a predetermined threshold value P of the cumulative number of printed pages thres are compared. The threshold value P thres is a threshold value preset as the cumulative number of printed pages that can detect changes in the toner remaining amount T n with sufficient accuracy, and in this embodiment, it is set to, for example, 100 pages. Information on this threshold value P thres is preset and stored in the memory 120 (for example, ROM). In this embodiment, in S302, the control unit 100 determines whether the cumulative number of printed pages stored in the memory 120 is equal to or greater than the above threshold value (100 pages or more in this embodiment). If the control unit 100 determines in S302 that the cumulative number of printed pages stored in the memory 120 is less than 100 pages, it controls to end the job operation without performing the low-speed detection operation (S110). On the other hand, if the control unit 100 determines in S302 that the cumulative number of printed pages stored in the memory 120 is 100 pages or more, it proceeds to the process of S107 and performs the low-speed detection operation as in the first embodiment. That is, the control unit 100 controls to change the rotation speed of the rotating shaft 223 to a second rotation speed (1 / 3 speed in this embodiment) slower than the first rotation speed during the backward rotation (S107). Then, the control unit 100 determines the toner remaining amount T act when the rotating shaft 223 is rotating at the second rotation speed based on the L output period / rotation of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the second rotation speed (S108). Further, the control unit 100 updates and stores the toner remaining amount T n acquired in S108 in the memory 120 (for example, non-volatile memory) as the current toner remaining amount T n (S109). Further, the control unit 100 sets (resets) the cumulative number of printed pages P n to an initial value (0 in this embodiment) (S303). Thereafter, the control unit 100 controls to end the job operation (S110).

[0073] For example, the cumulative number of printed pages P nis 95, and when the image formation of the job is 3 pages, it is as follows. In this case, the job operation ends without performing the low-speed detection operation. On the other hand, when the user instructs the input of job information as in the above case, the cumulative print count P n is 95, but when the image formation of the job is 6 pages, it is as follows. In this case, at the time of S302, the cumulative print count P n is incremented up to 101, and P n ≧P thres is satisfied. Therefore, in this case, the low-speed detection operation is performed in the same manner as in the first embodiment, and the job operation ends.

[0074] In this embodiment, the control unit 100 controls to perform the low-speed detection operation every predetermined number of printed pages (100 pages in this embodiment) when the toner remaining amount T n is within a predetermined range (range of 0% to 50% in this embodiment). Thereby, the toner remaining amount T n can be more accurately determined and stored in the memory 120. Also, in this embodiment, when the toner remaining amount T n exceeds a predetermined value (50% in this embodiment), or when the cumulative print count during the low-speed detection operation is less than a predetermined value (100 pages in this embodiment), the downtime can be reduced by not executing the low-speed detection operation.

[0075] Note that in this embodiment, the cumulative print count is used as a criterion for determining the execution of the low-speed detection operation, but it is not limited thereto. As long as it is an index value that enables estimation of whether the toner amount inside the developing container 221 has sufficiently changed, for example, an index value correlated with the cumulative print count during the low-speed detection operation, it can be used as a criterion. For example, the rotation time or the number of rotations of the rotating bodies (developing roller 204, supply roller 222, rotating shaft 223) of the photosensitive drum 201 and the developing device 227 may be used as a criterion. Also, for example, the toner remaining amount T nThe system may be configured to perform a slow-speed detection operation when the cumulative change in the value exceeds a predetermined threshold (when a predetermined condition is met). Alternatively, the system may be configured to perform a slow-speed detection operation when specified by the user.

[0076] Furthermore, in this embodiment, the remaining toner amount T n The system now performs a slow-speed detection operation when the toner level is within a predetermined range, and also performs a slow-speed detection operation every time a certain number of pages or more are printed. However, the toner level T n Regardless of the range, a reasonable effect can be obtained by performing a slow-speed detection operation every time a certain number of pages or more are printed.

[0077] As described above, this embodiment provides the same effects as in Example 1, while also reducing downtime caused by operations to detect the amount of toner.

[0078] [Example 4] Next, other embodiments of the present invention will be described. The basic configuration of the image forming apparatus in this embodiment is the same as that of the image forming apparatus in Embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those in the image forming apparatus of Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed descriptions are omitted.

[0079] In the embodiment described above, the remaining toner amount T when the rotating shaft 223 is rotating at the first rotational speed. n This was detected based on the detection result of the magnetic flux detection unit 226 when the rotating shaft 223 was rotating at a first rotational speed. However, the present invention is not limited to this embodiment. For example, there is a method for estimating toner consumption based on image information of the image to be formed and predicting the remaining toner amount. This method is also called a pixel counting method, and any known method can be used, for example.

[0080] Figure 11 is a block diagram illustrating the control configuration of the image forming apparatus 200 in this embodiment. In this embodiment, the image forming apparatus 200 has a pixel count unit 130, which is an acquisition unit that acquires consumption information regarding the amount of toner consumed from the developing container 211 based on image information defining the electrostatic latent image formed on the photosensitive drum 201. The pixel count unit 130 can calculate the amount of toner used by image formation from the pixel count value of the formed image. The pixel count value is typically the integral value of the density gradation signal value for each pixel. For example, the pixel count unit 130 accumulates the pixel count value for each page (image formation on one surface of the recording material P) that is performed. The pixel count unit 130 can also determine the toner consumption for one page by multiplying the pixel count value by the toner consumption per pixel which has been determined in advance. The control unit 100 can then determine the remaining toner amount inside the developing container 221 (toner chamber 221a) by subtracting the toner consumption amount obtained by the pixel count unit 130 from the amount of toner contained inside the developing container 221 (toner chamber 221a). However, the toner consumption amount based on the pixel count value may differ from the actual toner consumption amount due to changes in the installation environment of the image forming apparatus 200 or changes in the toner's tribo (charge amount). Thus, while the detection of the remaining toner amount using the pixel count method can be used instead of the detection of the remaining toner amount based on the output of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the first rotational speed, the detection accuracy may decrease.

[0081] Therefore, for example, when the rotating shaft 223 in S103 of Figure 7 is rotating at the first rotational speed, the remaining toner amount T act The determination (detection) is performed using a predicted value (pixel count method) based on image information. Then, the low-speed detection operation in S107 to S109 of Figure 7 can be performed based on the output of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the second rotational speed. Similarly, the toner remaining amount T in S103 of Figure 9 and S103 of Figure 10 when the rotating shaft 223 is rotating at the first rotational speed actThe determination (detection) is performed using predicted values ​​based on image information. Then, the low-speed detection operation in S107-S109 of Figure 9 and S107-S109 of Figure 10 can be performed based on the output of the magnetic flux detection unit 226 when the rotating shaft 223 is rotating at the second rotational speed.

[0082] As described above, the control of this embodiment, similar to the embodiment described above, can suppress a decrease in the accuracy of toner quantity detection in a configuration that includes a mechanism for detecting toner quantity by utilizing the change in distance between a magnetic member rotated by a rotating member and a detection unit.

[0083] [others] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the embodiments described above.

[0084] In the above-described embodiment, the image forming apparatus was a monochrome image forming apparatus. However, the present invention can also be applied to a color image forming apparatus having, for example, a plurality of image forming units, each equipped with an image carrier and a developing device. In this case, the present invention can be applied to each of the plurality of developing devices.

[0085] In the above-described embodiment, the toner stirring member was composed of a sheet-like member, but it is not limited to this, and may be composed of a paddle-like member or the like, or may be integrally formed with the rotating member.

[0086] In the above-described embodiment, the holding member was composed of a sheet-like member formed in a strip shape, but it is not limited to this, and may be composed of, for example, a sheet-like member that has at least some of the functions of a toner stirring member.

[0087] In the above-described embodiment, the case in which the amount of toner inside the developing container is detected and reported as the remaining toner amount (an amount that changes from 100% to 0%) was explained as an example. However, the amount of toner inside the developing container may also be detected and reported as the toner usage amount (an amount that changes from 0% to 100%).

[0088] Furthermore, by storing both the first toner quantity information and the second toner quantity information in the memory unit, and by providing toner quantity notifications based on the second toner quantity information when the latest information is the second toner quantity information, the toner quantity information can be effectively corrected (revised). [Explanation of Symbols]

[0089] 100 Control Unit 200 Image forming apparatus 201 Photosensitive drum 202 Developing Roller 221 Developing container 221a Toner Room 221b Developing room 223 Rotation axis 224 Magnets 225 Retaining member 226 Magnetic flux detection unit 227 Developing equipment 300 Toner level detection mechanism

Claims

1. An image carrier on which an electrostatic latent image is formed, A container for holding toner, A developing member that supplies toner contained in the container to the image carrier to develop the electrostatic latent image and forms a toner image on the image carrier, A rotating member provided inside the container, Magnetic material and A holding member connected to the rotating member and holding the magnetic member, the holding member moving inside the container while holding the magnetic member as the rotating member rotates, A detection unit that outputs a signal corresponding to the distance between itself and the magnetic member based on the action of magnetism, A drive unit that drives the rotating member to rotate, The drive unit is capable of controlling the rotating member to rotate at a first rotational speed and a second rotational speed slower than the first rotational speed, and the control unit acquires information based on the output of the detection unit. A storage unit capable of storing the aforementioned information, It has, The holding member is configured such that the shortest distance between the magnetic member and the detection unit while the rotating member is rotating is shorter when the amount of toner inside the container is a second amount, which is less than the first amount, than when the amount of toner inside the container is a first amount. The image forming apparatus is characterized in that the control unit can acquire first information based on the output of the detection unit when the rotating member is rotating at a first rotational speed and store it in the storage unit, and can acquire second information based on the output of the detection unit when the rotating member is rotating at a second rotational speed, and can store the second information in the storage unit so as to update the first information stored in the storage unit with the second information.

2. The image forming apparatus according to claim 1, characterized in that the control unit can control the drive unit to rotate the rotating member at a first rotational speed during a first period including the development period, and can control the drive unit to rotate the rotating member at a second rotational speed during a second period not including the development period.

3. The image forming apparatus according to claim 2, characterized in that the control unit controls the drive unit to rotate the rotating member at a second rotational speed during the second period when the amount of toner indicated by the first information acquired during the first period satisfies a predetermined condition, and performs the update based on the second information acquired during the second period.

4. The image forming apparatus according to claim 3, characterized in that the predetermined condition is that the amount of toner indicated by the first information acquired in the first period is less than or equal to a predetermined threshold.

5. The image forming apparatus according to claim 2, wherein, when the number of surfaces of the recording material onto which the toner image formed on the image carrier is transferred is defined as the number of image forming pages, the control unit controls the drive unit to rotate the rotating member at a second rotational speed during the second period if an index value correlated with the cumulative number of image forming pages since the previous update based on the second information satisfies a predetermined condition, and performs the update based on the second information acquired during the second period.

6. The image forming apparatus according to claim 5, characterized in that the predetermined condition is that the cumulative number of image-forming pages indicated by the index value is equal to or greater than a predetermined threshold.

7. The image forming apparatus according to claim 2, characterized in that the control unit controls the drive unit to rotate the rotating member at a second rotational speed during the second period if the cumulative change in the amount of toner amount indicated by the first information acquired during the first period since the previous update based on the second information satisfies a predetermined condition, and performs the update based on the second information acquired during the second period.

8. The image forming apparatus according to claim 7, characterized in that the predetermined condition is that the cumulative change amount is greater than or equal to a predetermined threshold.

9. The image forming apparatus according to claim 2, characterized in that the second period is the period after the formation of all toner images in a job, which is a series of operations for transferring and outputting the toner images formed on the image carrier onto one or more recording materials in response to a single start instruction.

10. An image carrier on which an electrostatic latent image is formed, A container for holding toner, A developing member that supplies toner contained in the container to the image carrier to develop the electrostatic latent image and forms a toner image on the image carrier, A rotating member provided inside the container, Magnetic material and A holding member connected to the rotating member and holding the magnetic member, the holding member moving inside the container while holding the magnetic member as the rotating member rotates, A detection unit that outputs a signal corresponding to the distance between itself and the magnetic member based on the action of magnetism, An acquisition unit that acquires consumption information relating to the amount of toner consumed from the container based on image information defining the electrostatic latent image formed on the image carrier, A drive unit that drives the rotating member to rotate, The drive unit is capable of controlling the rotating member to rotate at a first rotational speed and a second rotational speed slower than the first rotational speed, and the control unit acquires information based on the output of the detection unit and the consumption information, respectively. A storage unit that stores the aforementioned information, It has, The holding member is configured such that the shortest distance between the magnetic member and the detection unit while the rotating member is rotating is shorter when the amount of toner inside the container is a second amount, which is less than the first amount, than when the amount of toner inside the container is a first amount. The control unit controls the drive unit to rotate the rotating member at a first rotational speed during a first period including the development period, acquires first information based on the consumption amount information when the rotating member is rotating at the first rotational speed and stores it in the storage unit, and controls the drive unit to rotate the rotating member at a second rotational speed during a second period not including the development period, acquires second information based on the output of the detection unit when the rotating member is rotating at the second rotational speed, and stores the second information in the storage unit so as to update the first information stored in the storage unit with the second information.

11. The image forming apparatus according to any one of claims 1 to 10, characterized in that the holding member is flexible and can deform in accordance with the amount of toner inside the container when the rotating member is rotating.

12. The image forming apparatus according to any one of claims 1 to 10, characterized in that the holding member is rotatably connected to the rotating member via a pivot shaft, and can rotate around the pivot shaft in accordance with the amount of toner inside the container when the rotating member is rotating.

13. The detection unit outputs a first signal if the magnetic flux density of the magnetic flux passing through the detection unit is greater than or equal to a predetermined value, and outputs a second signal different from the first signal if the magnetic flux density is less than the predetermined value. The image forming apparatus according to any one of claims 1 to 10, characterized in that the control unit acquires the information based on the time during which the detection unit outputs the first signal each time the rotating member rotates once.

14. The image forming apparatus according to any one of claims 1 to 10, characterized in that it has a toner stirring member connected to the rotating member, which stirs the toner inside the container as the rotating member rotates.

15. The image forming apparatus according to any one of claims 1 to 10, characterized in that the drive unit is capable of rotating the image carrier at a first drive speed and a second drive speed slower than the first drive speed, and when the rotating member rotates at the first rotation speed, the image carrier rotates at the first drive speed, and when the rotating member rotates at the second rotation speed, the image carrier rotates at the second drive speed.

16. The image forming apparatus according to claim 15, characterized in that the electrostatic latent image can be formed when the image carrier is rotating at at least the first drive speed among the first drive speed and the second drive speed.

Images