JP5366477B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of more accurately supplying the developing device with the toner by correcting the amount of toner to be supplied to a developing device on the basis of the actual condition. <P>SOLUTION: The image forming apparatus includes: the developing device 4; a developer amount detecting device 45 for detecting an amount of a developer in the developing device 4; a developer consumption amount calculating device 38 for calculating a consumption amount of the developer consumed by development; a developer consumption amount integral value calculating device 35 for integrating developer consumption amounts, thereby calculating a developer consumption amount integrated value; a developer supplying device 5 for supplying the developer to the developing device 4; a control device 35 for controlling a developer supply operation to the developing device 4 by the developer supplying device 5, wherein the control device 35 causes the developer supply device 5 to perform a developer supply operation every time an integrated value of the consumption amount of the developer exceeds a supply threshold, and corrects the supply threshold on the basis of an amount of the developer in the developing device 4 detected by the developer amount detecting device 45. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that forms an image by developing an electrostatic image formed on an image carrier using an electrophotographic system or an electrostatic recording system with a developer. It is about.

  Conventionally, for example, in an electrophotographic image forming apparatus, an electrostatic image formed on an electrophotographic photosensitive member (photosensitive member) as an image carrier is visualized as a toner image with a developer toner using a developing device. . Thereafter, the toner image formed on the photosensitive member is transferred onto a transfer material such as a recording sheet as a transfer target. Then, an output image is obtained by fixing the toner image transferred onto the transfer material to the transfer material by heat and pressure.

  In such an image forming apparatus, there is known an apparatus that replenishes toner from a toner replenishing device as a developer replenishing device to the developing container as the toner in the developing container provided in the developing device is consumed by image formation. Yes. For example, when a toner supply container as a developer supply container provided in the toner supply apparatus is detachable from the main body (apparatus main body) of the image forming apparatus, when the toner in the toner supply container runs out, The toner supply container is replaced with a new toner supply container.

  The amount of toner replenished from the toner replenishing device to the developing container is generally controlled by the operation amount (operation time, etc.) of the toner replenishing device. That is, for example, when the toner amount detection means detects that the toner in the developing container has decreased, a toner supply request is issued to the toner supply device. Then, a predetermined amount of toner is replenished from the toner replenishing device to the developing container by driving a toner replenishing member such as a toner replenishing roller provided in the toner replenishing device by a predetermined amount (predetermined time or predetermined rotation speed). .

  Patent Document 1 describes a developing device that detects a remaining amount of toner in a developing chamber by a toner remaining amount detecting unit and supplies a predetermined amount of toner from a toner hopper into the developing chamber according to the detection output.

  In Patent Document 2, the level of the toner in the developing device is detected by the level detection means, and the toner is supplied from the toner supply hopper to the developing device according to the detected level, and the toner level in the developing device is kept constant. An image forming apparatus to be controlled is described.

  Generally, since the operation amount (operation time, etc.) of the toner replenishing device and the amount of toner discharged from the toner replenishing device are in a proportional relationship, the operation amount of the toner replenishing device is integrated to obtain the The integrated value of the toner discharge amount can be obtained.

  There is also an image forming apparatus that detects the remaining amount of toner in the toner supply container based on the integrated value of the toner discharge amount obtained from the integrated value of the operation amount of the toner supply device.

  Incidentally, the image forming apparatus is generally designed on the assumption that the operation amount of the toner replenishing device and the amount of toner discharged from the toner replenishing device are in a proportional relationship as described above. For example, it is designed on the assumption that 0.5 g of toner is discharged per rotation of the toner supply roller constituting the toner supply device.

  However, in practice, there are many cases where the operation amount of the toner replenishing device, for example, the rotation speed (or rotation time) of the toner replenishing roller and the amount of toner discharged from the toner replenishing device do not have a strictly one-to-one proportional relationship. That is, the temperature and humidity environment when the image forming apparatus is used, various physical property differences of the toner itself, the remaining amount of toner in the toner supply container, the number of rotations of the supply roller in one supply operation, and the like. The density of toner conveyed by a replenishing roller or the like slightly changes. As a result, the relationship between the operation amount of the toner supply device and the amount of toner discharged from the toner supply device varies.

  FIG. 12 shows an example of the relationship between the remaining amount (%) of toner in the toner supply container and the amount of toner discharged from the toner supply device per rotation of the toner supply roller. The devices A, B, and C shown in FIG. 12 are devices having the same specifications, and are designed on the assumption that the amount of toner discharged per rotation of the toner supply roller is 500 mg. However, the amount of toner actually discharged from the toner replenishing device by the rotation of the toner replenishing roller is different for each of the devices A, B, and C.

  FIG. 13 shows an example of the change in the amount of toner in the developing container as the number of image output sheets increases. Here, the toner replenishment amount per unit replenishment operation of the toner replenishment device assumed from the design of the image forming apparatus is referred to as “assumed replenishment amount”. The actual toner supply amount per unit supply operation of the toner supply device is referred to as “actual supply amount”.

  As shown in FIG. 13, in the case of “assumed replenishment amount = actual replenishment amount”, the toner amount in the developing container does not change because the same amount of toner as the original replenishment request is replenished. However, in the case of “assumed replenishment amount <actual replenishment amount”, the toner replenishment amount is more than required, and the toner amount in the developing container gradually increases. Conversely, if “assumed replenishment amount> actual replenishment amount”, the toner amount in the developing container decreases.

  As described above, when the assumed replenishment amount and the actual replenishment amount are deviated, the toner replenishment amount is too much or too little with respect to the original replenishment request, so that the toner amount in the developing container changes.

  Further, when the assumed replenishment amount deviates from the actual replenishment amount, the remaining amount of toner in the toner replenishing container is predicted based on the integrated value of the toner discharge amount that is expected from the integrated value of the rotation speed of the toner replenishing roller. In such an image forming apparatus, it is difficult to accurately predict the remaining amount of toner.

  These problems should be prevented by designing the toner replenishing device so that “assumed replenishment amount = actual replenishment amount”. However, in reality, factors such as component accuracy, use environment, and toner physical properties overlap, and it is very difficult to make the actual toner discharge amount of the toner replenishing device the same in all the devices.

To deal with such a problem, Patent Document 3 discloses that the predicted amount of discharged toner is corrected in accordance with the number of rotations of the supply screw in one supply operation. Japanese Patent Application Laid-Open No. H10-228688 discloses correcting the predicted amount of discharged toner according to the remaining amount of toner in the toner supply cartridge and the usage environment.
Japanese Patent Laid-Open No. 10-20640 JP 2002-40776 A JP 2003-316142 A JP 2004-109998 A

  However, the methods described in Patent Documents 3 and 4 are prediction corrections based on correction tables created based on past data, and do not necessarily correct the actual situation. .

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of correcting the amount of toner replenished to the developing device based on an actual situation and performing more accurate toner replenishment to the developing device. .

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to a developing device that develops an electrostatic image with a developer, a developer amount detecting device that detects the amount of developer in the developing device, and development based on image information of the electrostatic image. A developer consumption amount calculating device for calculating a developer consumption amount, a developer supplying device for supplying developer to the developing device, and a control device for controlling a developer supplying operation to the developing device by the developer supplying device; In the image forming apparatus, the control device replenishes the developer replenishing device with a predetermined amount of developer each time the developer consumption integrated value obtained by integrating the developer consumption exceeds a replenishment threshold. Until the replenishment operation is performed a predetermined number of times, and the replenishment threshold is corrected based on information relating to the developer amount in the developing device detected by the developer amount detection device. The replenishment An image forming apparatus, characterized in that no correction value.

  According to the present invention, the amount of toner replenished to the developing device can be corrected based on the actual situation, and more accurate toner replenishment to the developing device can be performed.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings. Note that the dimensions, materials, shapes, relative arrangements, and the like of the components in the following description are not intended to limit the scope of the present invention only to those unless otherwise specified.

Example 1
[Overall Configuration and Operation of Image Forming Apparatus]
With reference to FIG. 1, the overall configuration and operation of an embodiment of an image forming apparatus according to the present invention will be described. FIG. 1 shows a schematic cross-sectional configuration of an image forming apparatus 100 of the present embodiment. The image forming apparatus 100 according to the present exemplary embodiment is a laser beam printer using an electrophotographic method.

  The image forming apparatus 100 includes a drum-shaped electrophotographic photosensitive member as an image carrier, that is, a photosensitive drum 1. Around the photosensitive drum 1, there are arranged a charging roller 2 as a charging means, an exposure device 3 as an exposure means, a developing device 4 as a developing means, a transfer roller 6 as a transferring means, a cleaning device 7 as a cleaning means, and the like. Has been.

  The photosensitive drum 1 is supported at a substantially central portion in the main body (apparatus main body) 11 of the image forming apparatus so as to be rotatable in the arrow R1 direction (clockwise) in the figure. When the image forming operation is started, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 2 to a predetermined potential having a predetermined polarity. Thereafter, the surface of the photosensitive drum 1 is scanned and exposed by the exposure device 3 with a laser beam corresponding to the image information. As a result, an electrostatic image (latent image) is formed on the photosensitive drum 1. In this embodiment, the charging polarity of the photosensitive drum 1 is negative. In this embodiment, the exposure device 3 is configured as a laser scanner device that is a laser irradiation means.

  The electrostatic image formed on the photosensitive drum 1 is then visualized by supplying toner by the developing device 4 as the photosensitive drum 1 rotates. As a result, a toner image is formed on the photosensitive drum 1.

  In this embodiment, the developing method is a reversal developing method. That is, in the electrostatic image formed on the photosensitive drum 1, the charged polarity of the photosensitive drum 1 is applied to a portion (exposed portion, image portion) in which the negative charged charge is attenuated by exposure with the laser beam from the exposure device 3. Toner charged with the same polarity as the toner adheres. As will be described in detail later, in this embodiment, the developing device 4 uses a magnetic one-component developer, that is, toner, as the developer. Further, toner is supplied from the toner supply device (hereinafter referred to as “toner hopper”) 5 as the developer supply device to the developing device 4.

  The toner image formed on the photosensitive drum 1 is transferred onto the transfer material P by the action of the transfer roller 6 in the transfer region N where the photosensitive drum 1 and the transfer roller 6 abut. At this time, a transfer bias voltage having a polarity opposite to the normal charging polarity (negative polarity in this embodiment) of the toner is applied to the transfer roller 6, and a transfer electric field is formed in the transfer region N. The transfer material P is transferred from a cassette (not shown) as a transfer material storage unit by a transfer material supply roller 9 or the like in synchronization with the timing at which the toner image on the photosensitive drum 1 reaches the transfer region N. To N.

  Thereafter, the transfer material P onto which the toner image has been transferred is conveyed to a fixing device 8 as a fixing unit. The unfixed toner image carried on the transfer material P is heated on the transfer material P in the fixing device 8 by being heated by a heating roller 8a as a heating unit and by a pressure roller 8b as a pressing unit. It is fixed. The transfer material P on which the toner image is fixed is discharged outside the apparatus main body 11 as a recorded image.

  Further, the toner remaining on the photosensitive drum 1 after the transfer process (transfer residual toner) is removed and collected by the cleaning device 7. As a result, the photosensitive drum 1 is prepared for the subsequent image forming operation. The cleaning device 7 includes an elastic blade (cleaning blade) 7a that abuts on the photosensitive drum 1 as a cleaning member, and a collected toner container 7b that stores transfer residual toner removed from the photosensitive drum 1 by the cleaning blade 7a. .

[Developer]
Next, the developing device 4 will be further described with reference to FIG.

  The developing device 4 includes a developing container (developing device main body) 46 that stores toner as a developer. The developing container 46 is provided with a developing roller 41 as a developer carrying member that carries and conveys toner and supplies the toner to the electrostatic image on the photosensitive drum 1. Further, the developing container 46 is provided with a supply roller 43 as a developer supplying and collecting means for supplying toner to the developing roller 41 and collecting toner from the developing roller 41. Further, the developing container 46 is provided with a developing blade 42 which is a developer layer thickness regulating member as a developer regulating means for regulating the toner supplied onto the developing roller 41 by the supply roller 43 to form a toner layer. It has been. Further, the developing container 46 is provided with an agitation paddle 44 as a developer agitating means for mixing the replenishing toner as the replenishing developer replenished from the toner hopper 5 and the toner in the developing container 46. Further, the developing container 46 is provided with a toner amount detecting means 45 for detecting the toner amount in the developing container 46 as a developer amount detecting device.

  In this embodiment, a negatively chargeable non-magnetic one-component developer, that is, a toner is used as the developer.

The developing container 46 is partially open on the side facing the photosensitive drum 1. The developing roller 41 is rotatably supported by the developing container 46 so as to be partially exposed from the opening. The developing roller 41 has a volume resistivity of 1 Ωm (10 ² Ωcm) to 10 ⁸ Ωm (10 ¹⁰ Ωcm) in which a conductive agent such as carbon is dispersed. Or it has the elastic layer (elastic body) comprised by the combination. In the present embodiment, the developing roller 41 is a semiconductive elastic roller having a diameter of 20 mm formed by forming an elastic layer on a cored bar. The developing roller 41 is urged toward the photosensitive drum 1 by the urging means, and is in contact with the photosensitive drum 1 with a predetermined contact pressure. The developing roller 41 is rotationally driven in the direction of arrow R2 (counterclockwise) in the drawing. In other words, in this embodiment, the photosensitive drum 1 and the developing roller 41 are driven to rotate so that the surface movement directions of the photosensitive drum 1 and the developing roller 41 are in the forward direction.

In this embodiment, the supply roller 43 is an elastic roller formed by forming an elastic layer (elastic body) on the cored bar. In particular, in this embodiment, the supply roller 43 is an insulating sponge roller having a diameter of 16 mm. Further, the supply roller 43 is urged toward the developing roller 41 by the biasing means is in contact with the developing roller 41 at a predetermined contact pressure. The supply roller 43 is rotationally driven in the direction of arrow R3 (counterclockwise) in the drawing. In other words, in this embodiment, the developing roller 41 and the supply roller 43 are rotationally driven so that the surface movement directions of the developing roller 41 and the supply roller 43 are opposite to each other.

  In this embodiment, the process speed corresponding to the peripheral speed (surface moving speed) of the photosensitive drum 1 is 150 mm / sec, and the peripheral speed (surface moving speed) of the developing roller 41 is 225 mm / sec.

  An agitation paddle 44 that is a means for agitating and transporting the developer is provided in the inner side of the developing container 46 opposite to the opening of the developing container 46. The agitation paddle 44 is driven to rotate in the direction of the arrow R4 (clockwise) in the figure. The agitation paddle 44 agitates the toner in the developing container 46 and conveys the toner to a region near the contact portion between the developing roller 41 and the supply roller 43.

The toner conveyed to the region in the vicinity of the contact portion between the developing roller 41 and the supply roller 43 is given an electric charge by frictional charging due to sliding with the developing roller 41 as the supply roller 43 rotates. The charged toner receives a mirroring force from the developing roller 41 by the charge and is carried on the developing roller 41.

  The developing blade 42 is provided in the developing container 46 so as to be pressurized by the developing roller 41. The developing blade 42 is an elastic blade that contacts the developing roller 41 on the side surface on the free end side. The developing blade 42 may be configured by a leaf spring made of L-shaped SUS or the like, and may contact the developing roller 41 at the L-shaped edge portion.

  The toner supplied onto the developing roller 41 has its layer thickness regulated by the developing blade 42 and is given an electric charge. Thereby, a thin layer of toner is formed on the developing roller 41. Then, the toner carried in a thin layer on the developing roller 41 is supplied to the developing area as the developing roller 41 rotates. In the developing area, the toner is transferred from the developing roller 41 to the photosensitive drum 1 corresponding to the electrostatic image on the photosensitive drum 1. As a result, a toner image is formed on the photosensitive drum 1.

  Further, the toner remaining on the developing roller 41 without being developed even after passing through the developing region is rubbed by the supply roller 43 and peeled off from the developing roller 41. A part of the toner is supplied again onto the developing roller 41 together with the toner newly supplied onto the supply roller 43, and the rest is returned to the developing container 46.

  In the present embodiment, the supply roller 43 has two functions as the developer supply and recovery means, but the developer supply means and the developer recovery means may be provided separately. Further, the developing system is not limited to contact development in which the photosensitive member and the developer carrying member are in contact with each other, and the developer carrying member is separated from the photosensitive member and the developer carrying member so that the toner flies. For example, a jumping development method for transferring from the toner to the photosensitive member may be used.

  In the present embodiment, the developing device 4 is configured to be detachable from the apparatus main body 11. For example, every predetermined period determined from the life of important parts (developing roller, developing blade, etc.) constituting the developing device 4 (in this embodiment, the image output is set to 30,000 sheets in terms of A4 size). In addition, the developing device 4 can be removed from the apparatus main body 11 and replaced.

[Toner supply device]
In this embodiment, a toner hopper 5 that is a toner replenishing device (mechanism) as a developer replenishing device that replenishes the developing device 4 with a developer is provided above the developing device 4.

  The toner hopper 5 includes a toner supply container (hopper body) 53 as a developer supply container (supply developer storage unit). In this embodiment, the toner replenishing container 53 contains replenishing toner as a replenishing developer. In addition, the toner hopper 5 includes a roller-like member that is a developer supply rotating member, that is, a toner supply roller 51 as a developer supply member for supplying toner from the toner supply container 53 to the developing container 46 of the developing device 4. Have. Further, a stirring member 52 for loosening the toner in the toner supply container 53 is disposed in the toner supply container 53 of the toner hopper 5. The stirring member 52 is rotationally driven in the direction of arrow R5 (clockwise) in the drawing.

  Then, the toner hopper 5 rotates the toner supply roller 51 in accordance with a supply command from a control device to be described later, thereby passing the toner supply container 53 through the openings 54 and 47 provided in the toner supply container 53 and the developing container 46, respectively. Toner is replenished to the developing container 46. In the present embodiment, the toner hopper 5 can replenish a predetermined amount of toner from the toner replenishing container 53 to the developing container 46 for a predetermined driving amount of the toner hopper 5, that is, for a predetermined driving time of the toner replenishing roller 51. It is configured.

  The image forming apparatus 100 is provided with a control device that controls replenishment of the developer from the toner hopper 5 to the developing device 4 in accordance with the developer consumption by the developing process. As such a control device, a CPU provided in a control unit that comprehensively controls the operation of the image forming apparatus 100 or a dedicated electric circuit can be used. In this embodiment, the CPU 35 (FIG. 4) of the control unit provided in the apparatus main body 11 controls the toner supply operation by the toner hopper 5 in order to control the operation of the image forming apparatus 100 in an integrated manner. Yes.

  In this embodiment, as shown in FIG. 3, the toner hopper 5 itself is configured to be detachable from the apparatus main body 11. That is, the toner hopper 5 constitutes a supply cartridge (toner bottle) that can be attached to and detached from the apparatus main body A. When the toner for replenishment in the toner hopper 5 runs out, the toner hopper 5 can be always removed from the apparatus main body 11 and replaced to replace the developing device 4 with a necessary amount of toner. According to this configuration, the entire toner hopper 5 can be replaced with respect to the apparatus main body 11, dirt and toner scattering due to toner during toner replenishment can be suppressed, and toner replenishment can be easily performed.

[Toner amount detection means and video count device]
In this embodiment, in toner replenishment control, a toner amount detecting unit as a developer amount detecting device for detecting the amount of toner in the developing container, and a developer consumption calculating device for calculating the developer consumption amount in the developing process. Video counting devices.

  The image forming apparatus according to the present exemplary embodiment includes a developing device that develops an electrostatic image with a developer, a toner amount detection unit, and a video count device. The image forming apparatus according to the present exemplary embodiment includes a developer consumption integrated value calculating device that calculates the developer consumption integrated value by integrating the developer consumption, and a developer supply device that supplies the developer to the developer. And a toner hopper 5. Further, the image forming apparatus according to the present exemplary embodiment includes a CPU 35 (FIG. 4) as a control device that controls a developer replenishing operation to the developing device by the developer replenishing device. In this embodiment, the control device causes the developer replenishing device to perform a predetermined amount of developer replenishment operation every time the developer consumption integrated value exceeds the replenishment threshold, and the development detected by the developer amount detecting device. The replenishment threshold value is corrected based on the developer amount in the apparatus. This will be described in more detail below.

Toner amount detection means First, the toner amount detection means 45 as a developer amount detection device used in this embodiment will be described.

  The CPU 35 (FIG. 4) provided in the apparatus main body 11 obtains information on the height of the upper surface (hereinafter referred to as “toner surface”) of the toner stored in the developing container 46 from the toner amount detection unit 45. Thus, the CPU 35 detects the amount of toner in the developing container 46 and controls the toner replenishing operation from the toner hopper 5 to the developing container 46 according to a control procedure described later. In this embodiment, the CPU 35 maintains the toner surface within a certain range from the toner amount control level γ to δ within the movable range of the stirring paddle 44 shown in FIG. 2 based on the detection result of the toner amount detecting means 45. The toner replenishing operation is controlled.

  More specifically, the developing container 46 is provided with a stirring paddle 44 that can rotate in the direction of arrow R4. The stirring region where the toner in the developing container 46 and the toner replenished from the toner hopper 5 are stirred substantially corresponds to the movable range of the stirring paddle 44.

  A toner amount detection means 45 configured as an optical detection means (toner surface detection means) for detecting the height of the toner surface in the stirring area by a light detection method is disposed so as to sandwich the stirring area. The toner amount detection unit 45 includes a light emitting unit 45 a including a light emitting element and a light receiving unit 45 b including a light receiving element, which are disposed outside the developing container 46. The toner amount detection means 45 includes windows 45c1 and 45c2 that are disposed on the wall surface of the developing container 46 and transmit light.

  When the toner surface changes with the rotation of the stirring paddle 44, the ratio of the light transmission time to the time for which the stirring paddle 44 makes one rotation is measured, that is, the information on the height of the toner surface in the stirring region, that is, the toner Get quantity information. This toner amount information can be used as it is. However, in this embodiment, in order to reduce the influence of the measurement error, an average value (toner amount average value) L of toner amount information is calculated for every five image outputs, and the amount of toner in the developing container 46 is calculated. When judging, the latest toner amount average value L is always used. In this embodiment, the CPU 35 calculates the toner amount average value L. In this embodiment, the CPU 35 sequentially stores the calculated toner amount average value L in a nonvolatile memory 36 (FIG. 4) as a storage device connected to the CPU 35. In this embodiment, the nonvolatile memory 36 is provided in the apparatus main body 11.

  In the present exemplary embodiment, the toner amount detection unit 45 includes a “toner low level” corresponding to the first toner amount control level γ and a “toner high level” corresponding to the second toner amount control level δ. One level of toner amount can be detected.

Video Counting Device Next, a video counting device as a developer consumption calculating device used in this embodiment will be described. In this embodiment, the video count device calculates the video count number according to image information for forming an electrostatic image on the photosensitive drum 1. Since the video count number has a correlation with the amount of toner consumed when developing the electrostatic latent image (toner consumption amount), the toner consumption amount is estimated from the video count number.

  FIG. 4 is a block diagram for explaining the video counting device 38 in the present embodiment. FIG. 5 is a schematic diagram for explaining the principle of the video count (pixel count) method.

  In this embodiment, the level of the output signal of the exposure device 3 is counted for each pixel in order to replenish the developing container 46 with an amount of toner corresponding to the amount of toner consumed by developing the electrostatic image. The In this embodiment, this counting is performed as follows.

  The exposure apparatus 3 that is a laser scanner apparatus in the present embodiment includes a semiconductor laser, a rotating polygon mirror (polygon mirror), a lens, and the like (not shown). Laser light emitted from the semiconductor laser is swept by a rotating polygon mirror and imaged as a spot on the photosensitive drum 1 by a lens such as an f / θ lens and a fixed mirror that directs the laser light toward the photosensitive drum 1. The The laser light imaged on the photosensitive drum 1 scans and exposes the photosensitive drum 1 along a direction (main scanning direction) substantially parallel to the rotation axis of the photosensitive drum 1 to form an electrostatic image on the photosensitive drum 1. To do.

  Information on an image to be an electrostatic image is input to the pulse width modulation circuit 31 via the image processing circuit 30 from a personal computer or an image input scanner. Then, for each input pixel image signal, a laser drive pulse having a width (time length) corresponding to the level is supplied from the pulse width modulation circuit 31 to the exposure apparatus 3. The exposure device 3 causes the semiconductor laser to emit light for a time corresponding to the pulse width. Therefore, the semiconductor laser is driven for a longer time for a high density pixel and for a shorter time for a low density pixel.

  Specifically, as shown in FIG. 5A, a laser driving pulse is formed. That is, a wider laser drive pulse W is applied to a high-density pixel image signal, and a narrower laser drive pulse S is applied to a low-density pixel image signal. Thus, a laser-driven pulse I having an intermediate width is formed.

  Therefore, as shown in FIG. 5B, the photosensitive drum 1 is exposed to a long range in the main scanning direction for high density pixels and to a short range in the main scanning direction for low density pixels. The In other words, the dot size of the electrostatic image differs depending on the pixel density. Therefore, the toner consumption amount for the high density pixel is larger than the toner consumption amount for the low density pixel. FIG. 5B schematically shows the shapes L, M, and H of the electrostatic images of low, medium, and high density pixels, respectively.

  In addition to the above processing, the output signal of the pulse width modulation circuit 31 is supplied to one input of the AND gate 33. A clock pulse (pulse shown in FIG. 5C) from the clock pulse oscillator 32 is supplied to the other input of the AND gate 33. Therefore, from the AND gate 33, as shown in FIG. 5D, the number of clock pulses corresponding to the pulse width of each of the laser driving pulses S, I, and W, that is, the number corresponding to the density of each pixel. A clock pulse is output. The number of clock pulses is integrated by the counter 34 for each image, and the video count number corresponding to the image printing ratio of the electrostatic image is finally calculated by adding the respective pixels to the output image.

  In this embodiment, the video count device 38 is configured by including the clock pulse oscillator 32, the AND gate 33, and the counter 34 described above.

[Toner supply control]
Next, the toner replenishment control of this embodiment will be described.

  The video count number calculated by the video count device 38 as described above substantially corresponds to the amount of toner consumed by the developing device 4 to form a toner image of the output image. Therefore, in this embodiment, this video count number is supplied to the CPU 35. The CPU 35 calculates the “toner consumption per image output” consumed by the developing device 4 based on the video count number. This “toner consumption per image output” corresponds to “amount of toner to be replenished for one image output”. That is, based on the video count from the video count device 38, the CPU 35 calculates the toner amount t1 to be replenished for each image output for each image output.

  In this embodiment, the toner replenishing operation is not directly performed on the toner amount t1 to be replenished. That is, the CPU 35 obtains an integrated value t2 of the toner amount to be replenished by accumulating the toner amount t1 to be replenished for each image output. In the present embodiment, the CPU 35 sequentially stores the integrated value t2 in a non-volatile memory 36 as a storage device connected to the CPU 35. This integrated value t2 is the amount of toner to be supplied to the developing device 4. Thus, in this embodiment, the CPU 35 also has a function as a developer consumption integrated value calculation device.

  In this embodiment, the amount of toner that the toner hopper 5 replenishes from the toner replenishing container 53 to the developing container 46 in one operation is set in advance as the replenishment threshold t3. In this embodiment, the replenishment threshold t3 is stored in advance in a nonvolatile memory 36 as a storage device connected to the CPU 35.

  Then, when the integrated value t2 of the toner amount to be replenished exceeds the replenishment threshold t3, the CPU 35 operates the replenishment drive device 37 (FIG. 4) constituting the toner hopper 5 once. The replenishment drive device 37 rotates the toner replenishment roller 51, and the rotation speed of the toner replenishment roller 51 by operating the replenishment drive device 37 once is set to be substantially constant. .

  Next, the CPU 35 subtracts the supply threshold value t3 from the integrated value t2 of the toner amount to be supplied. The toner amount t1 to be replenished is continuously accumulated on the remaining accumulated value t2 obtained by subtracting the replenishment threshold t3.

  More specifically, in this embodiment, one operation of the toner hopper 5 is determined as a constant supply operation for the toner supply roller 51 to rotate twice. That is, one of the great features of this embodiment is that the operation of the toner hopper 5 is fixed once without changing the operation time of the toner hopper 5 in response to the toner supply request. Thus, in this embodiment, the rotation amount of the toner replenishing roller 51 in one operation of the toner hopper 5 is fixed, in particular, an integer rotation (two rotations in this embodiment). Thus, according to the present embodiment, it is possible to obtain an effect that the toner can be stabilized to a predetermined replenishment amount as compared with a device in which the rotation amount of the toner replenishment roller 51 is different every time the toner replenishment operation is performed.

  Next, the flow of the toner supply operation will be described with reference to the flowchart of FIG.

  After the power supply is turned on (step 1), the image forming apparatus 100 enters a standby state when a predetermined start-up preparation is completed (step 2). When the image forming apparatus 100 receives a print signal in the standby state, the image forming apparatus 100 starts a printing operation and sequentially activates the photosensitive drum 1, the charging roller 2, the developing device 4, and the like (step 3). The image forming apparatus 100 activates the exposure apparatus 3 to form an electrostatic image at the time when the preparation of each unit is completed, and starts acquiring video count data at the same time (step 4). Thereafter, the image forming apparatus 100 stops the exposure apparatus 3 when the formation of the electrostatic image is completed, and simultaneously ends the video count integration to acquire the video count value (steps 5 and 6).

  The CPU 35 calculates the amount of toner consumed in the developing device 4, that is, the toner amount t1 to be replenished, based on the video count value for each image formation (step 7). The CPU 35 accumulates the toner amount t1 to be replenished, thereby sequentially storing the accumulated value t2 of the toner amount to be replenished in the nonvolatile memory 36 (step 8).

  Next, the CPU 35 acquires toner amount information by the toner amount detecting means 45 (step 9). The CPU 35 obtains an average value (toner amount average value) L of the toner amount information for every predetermined number of image output sheets, and performs a process of storing it in the nonvolatile memory 36 (step 10). In this embodiment, the CPU 35 updates the latest toner amount average value L every five image outputs.

  Next, the CPU 35 compares the integrated value t2 of the toner amount to be replenished with the replenishment threshold t3 (step 11). When the CPU 35 determines that “integrated value t2 ≦ replenishment threshold t3”, the toner replenishment request to the toner hopper 5 is not made. In this case, the process shifts to a job end determination (step 12) described later. On the other hand, when the CPU 35 determines that “integrated value t2> replenishment threshold t3”, the toner hopper 5 performs the toner replenishment operation once (step 14). Thereafter, the CPU 35 subtracts the supply threshold t3 from the integrated value t2 (step 15).

  Next, the CPU 35 determines whether or not the number N of toner replenishment operations performed without correcting a replenishment threshold t3, which will be described later, has exceeded 5 as the predetermined interval Nt (step 16). When it is determined that “N> 5”, the CPU 35 compares the toner amount average value L with the toner amount threshold value (steps 17 and 19). In this embodiment, as the toner amount threshold, the “toner amount low threshold” corresponding to the first toner amount control level γ and the “toner amount Hi threshold” corresponding to the second toner amount control level δ are the CPU 35. Is stored in advance in a nonvolatile memory 36 as a storage device connected to the. In this embodiment, the toner amount average value L is the average value of the toner amount in a predetermined period immediately before the replenishment operation, but is not limited to this, and the toner amount average value including the toner amount after replenishment is included. It is good also as L. The amount of toner in the developing device in the vicinity of replenishment may be solved.

  That is, the CPU 35 first compares the toner amount average value L with the toner amount Hi threshold (step 17). When the CPU 35 determines that “toner amount average value L> toner amount Hi threshold value”, the CPU 35 performs correction to increase the replenishment threshold value t3 by a predetermined amount α (step 18). On the other hand, if it is determined in step 17 that “toner amount average value L ≦ toner amount Hi threshold”, the CPU 35 then compares the toner amount average value L with the toner amount low threshold (step 19). ). Then, the CPU 35 performs correction for reducing the replenishment threshold t3 by a predetermined amount β when it is determined that “the toner amount average value L <the toner amount low threshold value” (step 20).

  When the CPU 35 determines that “N ≦ 5” in step 16 and when it is determined in steps 17 and 19 that “toner amount low threshold ≦ toner amount average value L ≦ toner amount Hi threshold”. Adds 1 to the number N of toner replenishment operations (step 21). On the other hand, when the supply threshold value t3 is corrected in step 18 or step 20, the CPU 35 resets the toner supply operation count N to zero. In this embodiment, the number N of toner replenishment operations and a predetermined interval Nt (5 in this embodiment) that is a threshold value are stored in a nonvolatile memory 36 as a storage device connected to the CPU 35.

  Next, the CPU 35 determines whether or not the job (a series of image forming operations on one or a plurality of transfer materials according to one image formation start command) has been completed (step 12). If the CPU 35 determines that the job has not yet ended and it is necessary to print continuously, the CPU 35 returns to the image formation by exposure (step 4) and operates the exposure device 3 again. On the other hand, if the CPU 35 determines that there is no remaining image output in the job, the CPU 35 stops each unit in order, ends the image forming operation (step 13), and returns to the standby state (step 2).

Here, a more specific operation example according to the present embodiment will be described. Various settings are as follows.
A: Toner amount of the maximum density toner image formed on the photosensitive drum (= 0.6 mg / cm ² )
S: Area of transfer material (A4 size) (= 21.0 cm × 29.7 cm)
R: Image printing ratio calculated from video count (= 0 to 100%)
t1: Amount of toner to be replenished per image output (= toner consumed per image output)
t1 = A × S × R
t2: integrated value of toner amount to be replenished t3: replenishment threshold (= initial value is 600 mg)
Nt: Minimum interval for correcting the supply threshold t3 (= toner supply operation 5 times)
α: Correction amount for correcting the replenishment threshold t3 when the toner amount in the developing container exceeds the Hi level (= 10 mg)
β: Correction amount for correcting the replenishment threshold t3 when the toner amount in the developing container falls below the Low level (= 10 mg)

  In the present embodiment, the toner amount (developer consumption amount) t1 to be replenished is calculated by the video count device, but is not limited thereto. For example, image information sent from a PC (personal computer) or the like may be developed, and the CPU 35 may calculate the toner consumption based on the printing rate of the image information. In this case, the CPU 35 is a printing rate calculation device and a developer consumption amount calculation device.

  In this example, the design value of the toner amount in the developing container 46 is 70 g. Then, when the toner amount in the developing container 46 exceeds 75 g, it is determined that the toner Hi level is exceeded, and when the toner amount in the developing container 46 becomes less than 65 g, the toner level is below the Low level. The toner amount detection means 45 has been adjusted so as to determine. Further, in the correction of the replenishment threshold t3 when the toner Hi level is exceeded, the replenishment threshold t3 is increased by 10 mg, and in the correction of the replenishment threshold t3 when the toner is lower than the Low level, the replenishment threshold t3 is decreased by 10 mg. I made it.

  By the way, the predetermined interval Nt is a minimum interval for correcting the supply threshold t3. That is, in this example, the correction of the next supply threshold value t3 is not performed until the toner supply operation is performed at least Nt (= 5) times after the previous supply threshold value t3 is corrected. After the toner amount detection means 45 detects the toner Hi level or the toner Low level, the toner replenishment amount by one operation of the toner hopper 5 is corrected and reflected as a change in the toner amount in the developing device 4. In principle, a certain time difference occurs. Therefore, the predetermined interval Nt is set so that the replenishment threshold t3, that is, the toner replenishment amount is not corrected by one operation of the toner hopper 5 too frequently. That is, the control device does not correct the supply threshold unless the supply operation is performed a predetermined number of times. If the predetermined interval Nt is too small, the replenishment threshold t3 is frequently corrected, and there is a concern that the toner amount detection means 45 may become too sensitive to the detection result. On the other hand, when the predetermined interval Nt is too large, on the contrary, the correction of the toner amount with respect to the toner Hi level and the toner Low level becomes insensitive. The predetermined interval is not particularly limited, but Nt = 3 to 10 times was good in the study by the present inventors. If the toner replenishment amount due to one operation of the toner hopper 5 is corrected and reflected in the change in the toner amount in the developing device 4 so that there is almost no time difference, Nt = 1 is set. May be.

  FIG. 7 shows the transition of the toner amount in the developing container 46 obtained by conducting the durability test in the image forming apparatus 100 of the present embodiment.

  In FIG. 7, when “assumed replenishment amount = actual replenishment amount”, the same amount of toner as that of the original replenishment request is replenished, so the toner amount in the developing container 46 does not change. In this embodiment, the assumed replenishment amount corresponds to the replenishment threshold value t3, so this state can also be said to be “replenishment threshold value t3 = actual replenishment amount”.

  In the case of “assumed replenishment amount <actual replenishment amount”, the toner replenishment amount is larger than required, so the toner amount in the developing container 46 gradually increases. In this embodiment, the toner amount detection means 45 detects the toner Hi level. Then, correction for increasing the replenishment threshold t3 is performed. When the supply threshold t3 increases, the toner supply operation becomes sparse. For this reason, the amount of toner replenished to the developing container 46 decreases, and the amount of toner in the developing container 46 gradually decreases.

  In the case of “assumed replenishment amount> actual replenishment amount”, the toner replenishment amount is smaller than required, so the toner amount in the developing container 46 gradually decreases. In this embodiment, the toner low level is set by the toner amount detection unit 45. It detects and correct | amends which makes supply threshold value t3 small. When the replenishment threshold t3 becomes smaller, the toner replenishment operation becomes frequent. Therefore, the amount of toner replenishment to the developing container 46 increases, and the amount of toner in the developing container 46 gradually increases.

  As described above, according to the present embodiment, even when the assumed replenishment amount and the actual replenishment amount are deviated, the toner amount in the developing container 46 is detected by the toner amount detecting means 45, and the detection result is determined according to the detection result. The replenishment threshold value t3 is corrected. As a result, the replenishment threshold value t3 is gradually feedback-corrected, and approaches the actual toner replenishment amount value by one operation of the toner hopper 5. Therefore, the image forming apparatus 100 can operate substantially in a state of “assumed replenishment amount (replenishment threshold t3) = actual replenishment amount”.

  The value of the replenishment threshold value t3 that has settled down steadily by performing the toner replenishment control of this embodiment is very accurate as a value unique to the apparatus. As a result, in this embodiment, it is possible to always replenish an appropriate amount of toner at an appropriate timing without the amount of toner replenishment being too large or too small. Further, the present embodiment does not need to perform complicated replenishment tables or replenishment amount correction control, and can be implemented with a very simple device and control. Therefore, according to the present embodiment, high reliability can be exhibited with a simple configuration.

  In this embodiment, the toner hopper 5 is designed with particular care so that the same amount of toner can be discharged each time by fixing the amount of toner replenished at one time by the toner hopper 5. It ’s fine. Therefore, the toner hopper 5 can be simplified. Further, it is possible to eliminate the need for complicated predictive control that corrects the relationship between the driving time of the toner hopper 5 and the toner discharge amount.

  Furthermore, in the present embodiment, the state of “assumed replenishment amount (replenishment threshold t3) = actual replenishment amount” can be substantially achieved. Therefore, the integrated value of the replenishment threshold t3, that is, the value obtained by integrating the toner replenishment amount t3 by one toner replenishment operation of the toner hopper 5 by the number of operations of the toner hopper 5, is the value of the toner actually replenished by the toner hopper 5. It can be said that the integrated value of the quantity. Therefore, for example, the CPU 35 can detect the remaining amount of toner in the toner hopper 5 by comparing the initial filling amount of the toner hopper 5 with the integrated value of the replenishment threshold value t3. In this case, the CPU 35 also has a function as a replenishment developer remaining amount detecting means for detecting the remaining amount of developer in the developer replenishing device. In this case, when the CPU 35 detects that the toner in the toner hopper 5 has run out, the CPU 35 notifies the fact on the display unit provided in the apparatus main body 11 or the display unit of the device connected to the apparatus main body 11. , It may have a function as a notification means. Since the replenishment threshold t3 is always corrected to be equal to the actual replenishment amount, if the remaining amount of toner in the toner hopper 5 is detected by this method, the remaining amount can be detected with a simple configuration and with very high accuracy. Can be done.

  As described above, according to this embodiment, the amount of toner replenished to the developing device 4 can be corrected based on the actual situation, and more accurate toner replenishment to the developing device 4 can be performed. That is, according to the present embodiment, it is possible to supply the developing device 4 with high precision. This stabilizes the toner amount in the developing device 4 and stabilizes the toner charge amount, thereby suppressing fog (a phenomenon in which the toner adheres to a white background where the toner should not adhere) and density unevenness. Can do. Therefore, according to the present embodiment, high-quality image formation can be performed over a long period of time.

Example 2
Next, another embodiment according to the present invention will be described. In the image forming apparatus of the present embodiment, elements having the same or equivalent functions and configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The present embodiment is different from the first embodiment mainly in the following points. That is, (1) the photosensitive drum, the charging roller, the cleaning device, the developing device, and the like are integrally configured as a process cartridge that can be attached to and detached from the apparatus main body, and (2) the image forming apparatus is an inline-type full-color laser. It is a beam printer.

  FIG. 8 shows a schematic cross section of the main part of the image forming apparatus 200 of this embodiment. FIG. 9 shows a schematic cross-sectional configuration of the process cartridge 10 provided in the image forming apparatus 200 of the present embodiment.

  The image forming apparatus 200 according to the present exemplary embodiment includes first, second, and second images that form yellow (Y), magenta (M), cyan (C), and black (K) images as a plurality of image forming units, respectively. It has third and fourth image forming units 12Y, 12M, 12C, and 12K.

  The configurations and operations of the image forming units 12Y, 12M, 12C, and 12K are substantially the same except that the color of the toner used is different. Accordingly, in the following, unless there is a particular distinction, the subscripts Y, M, C, and K given to the reference numerals in the drawing are omitted to indicate that they are elements provided for any color, and are summarized Explained.

  Each image forming unit 12 is provided with a photosensitive drum 1, a charging roller 2, an exposure device 3, a developing device 4, and a cleaning device 7. Further, an intermediate transfer belt 201, which is an endless belt member as an intermediate transfer member (second image carrier), is disposed so as to be capable of rotating around so as to face each photosensitive drum 1 of each image forming unit 12. Yes. In each image forming unit 12, a primary transfer roller 202 as a primary transfer unit is disposed so as to come into contact with the inner peripheral surface of the intermediate transfer belt 201 at a position facing the photosensitive drum 1. In addition, a secondary transfer roller 203 as a secondary transfer unit is disposed so as to contact the outer peripheral surface of the intermediate transfer belt 201 at a position facing one of a plurality of rollers on which the intermediate transfer belt 201 is stretched. Has been.

  In each image forming unit 12, the photosensitive drum 1 and the charging roller 2, the developing device 4, and the cleaning device 7 as process means that act on the photosensitive drum 1 are integrally assembled, and are attached to the apparatus main body 11. A detachable process cartridge 10 is configured.

  The process cartridge 10 is removed from the apparatus main body 11 and replaced when a predetermined endurance life is reached. According to the process cartridge system, consumable parts can be easily replaced, and the maintainability of the image forming apparatus is greatly improved. Also, by exchanging the process cartridge, important components in the electrophotographic system can be replaced with new ones, so that a high-quality image can always be obtained.

  In this embodiment, the toner hopper 5 is detachably attached to the apparatus main body 11 and the process cartridge 10 independently in each image forming unit 12.

  In this embodiment, the process cartridges 10Y, 10M, 10C, and 10K of the first to fourth image forming units 12Y, 12M, 12C, and 12K are respectively yellow (Y), magenta (M), cyan (C), It contains toner for each color of black (K). Also, the toner hoppers 5Y, 5M, 5C, and 5K of the first to fourth image forming units 12Y, 12M, 12C, and 12K are respectively yellow (Y), magenta (M), cyan (C), and black (K ) For each color toner supply.

  For example, when forming a full-color image, the toner image formed on the surface of each photosensitive drum 1 of each image forming unit 12 is sequentially superimposed and transferred onto the intermediate transfer belt 201 by the action of each primary transfer roller 202. (Primary transfer). At this time, a primary transfer bias voltage having a polarity opposite to the normal charging polarity of the toner is applied to each primary transfer roller 202.

  The color toner images that have been multiple-transferred onto the intermediate transfer belt 201 are collectively transferred (secondary transfer) onto the transfer material P by the action of the secondary transfer roller 203. At this time, a secondary transfer bias voltage having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 203.

  Thereafter, the transfer material P is separated from the intermediate transfer belt 201 and conveyed to a fixing device (not shown). After the toner image on the transfer material P is fixed by heating and pressing, the transfer material P The recorded image is discharged outside the apparatus main body 11.

  In a color image forming apparatus, a multi-color image is superimposed on a single transfer material P, so image defects such as fog (a phenomenon in which toner adheres to a white background where the toner should not adhere) and density unevenness can be prevented. Therefore, a higher level than that of the monochrome image forming apparatus is required. For this reason, it is desired to more accurately control the toner supply to the developing device 4. This is because if the toner amount in the developing device 4 is not stable, the charge amount of the toner becomes unstable, which causes fogging and uneven density. Therefore, the toner replenishing method according to the present invention can be suitably used for replenishing toner of each color even in the color image forming apparatus as in this embodiment. As a result, the same effects as described in the first embodiment can be obtained for each color, and the color image can be further improved in image quality.

  The process cartridge system as described in the present embodiment can also be employed in the image forming apparatus 100 described in the first embodiment.

Example 3
Next, still another embodiment of the image forming apparatus according to the present invention will be described. In the image forming apparatus of the present embodiment, elements having the same or equivalent functions and configurations as those of the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, as shown in FIG. 10, non-volatile memories 13 and 14 as storage devices are provided for the process cartridge 10 and the toner hopper (replenishment cartridge) 5 that are detachable from the apparatus main body 11. When the process cartridge 10 and the toner hopper 5 are respectively attached to the apparatus main body 11, various information can be read and written between the CPU 35 of the apparatus main body 11 and the nonvolatile memories 13 and 14.

  The non-volatile memory 13 of the process cartridge 10 stores an integrated value t2 of the toner amount to be replenished to the developing device 4 included in the process cartridge 10. On the other hand, in the nonvolatile memory 14 of the toner hopper 5, an integrated value of the replenishment threshold t3 obtained by integrating the latest replenishment threshold t3 and the replenishment threshold t3 used at that time each time the toner hopper 5 performs a predetermined replenishment operation. Remember.

  As timings for reading and writing information with respect to the nonvolatile memories 13 and 14, for example, the timing described below can be cited. That is, the information held by the CPU 35 is written in the nonvolatile memories 13 and 14 when the cartridge mounting / demounting door of the apparatus body 11 is opened or when the apparatus body 11 is powered off. Further, when the cartridge attachment / detachment door is closed or when the power of the apparatus main body 11 is turned on, the information of the nonvolatile memories 13 and 14 is read out to the CPU 35. In this way, the unique t2 value, t3 value, and t3 integrated value stored in the respective nonvolatile memories 13 and 14 can always be used.

  As described in the first embodiment, the t3 value settled to the steady state by actual feedback is very accurate as a value inherent to the device. Therefore, the t3 value is stored in the nonvolatile memory 14 provided in the toner hopper 5 as a value unique to the toner hopper 5. As a result, even when the power of the apparatus main body 11 is turned off or the toner hopper 5 is attached to another apparatus main body 11, it is possible to always replenish the toner optimally, and the toner in the developing device 4 The amount is stable and the image quality is improved.

  Further, even when the remaining amount of toner in the toner hopper 5 is detected by counting the cumulative driving time of the toner hopper 5, the detection accuracy can be greatly improved. That is, the accumulated t3 value is stored in the nonvolatile memory 14 of the toner hopper 5, and the remaining amount of toner in the toner hopper 5 is detected based on the value. Thus, even when the power of the apparatus main body 11 is turned off or the toner hopper 5 is attached to another apparatus main body 11, the toner hopper 5 can have information on the remaining amount of toner by itself. Become. Therefore, it is possible to always detect the remaining amount of toner accurately.

  Further, the integrated value t2 of the toner amount to be replenished is stored in the nonvolatile memory 13 provided in the process cartridge 10. As a result, even when the power of the apparatus main body 11 is turned off or when the process cartridge 10 is attached to another apparatus main body 11, the process cartridge 10 provides information on the amount of toner that should have been replenished. It becomes possible to have oneself. Therefore, it is possible to prevent the toner from being replenished, the amount of toner in the developing device 4 is stabilized, and the image quality is improved.

  As mentioned above, although this invention was demonstrated according to the specific Example, it should be understood that this invention is not limited only to the above-mentioned embodiment.

  For example, electrophotographic image forming apparatuses include copying machines, printers (for example, LED printers, laser beam printers, etc.), facsimile machines, word processors, and the like.

  The process cartridge is a cartridge in which a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive member are integrally formed, and the cartridge can be attached to and detached from the image forming apparatus main body. Alternatively, the process cartridge is a cartridge in which at least one of a charging unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member are integrally formed so as to be detachable from the main body of the image forming apparatus. Alternatively, the process cartridge is a cartridge in which at least the developing means and the electrophotographic photosensitive member are integrally formed so as to be detachable from the image forming apparatus main body.

  The cartridge that can be attached to and detached from the image forming apparatus main body is not limited to the process cartridge, and the developing means can be a developing cartridge that can be attached to and detached from the image forming apparatus main body independently.

  In the above-described embodiment, the toner amount detection unit 45 is described as an optical detection unit. However, the present invention is not limited to this. For example, in the example shown in FIG. 11, a toner amount detection means 45 made of a piezoelectric element or the like is provided in the vicinity of a rotatable stirring paddle 44 that is a means for stirring and transporting toner in the developing container 46.

  In the above-described embodiment, the developer supply rotating body as the developer supply member provided in the toner hopper 5 has been described as being in the form of a roller, but this may be in the form of a screw.

  The present invention can also be applied to a case where a two-component developer mainly composed of a mixture of non-magnetic toner particles (toner) and magnetic carrier particles (carrier) is used as the developer. In this case, the replenishment developer may be either toner or a mixture of toner and carrier.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a developing device and a toner hopper provided in an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a toner hopper provided in an image forming apparatus according to an embodiment of the present invention. It is a block diagram for demonstrating an example of the video count apparatus used for the toner replenishment control according to this invention. It is a schematic diagram for demonstrating the principle of a video count system. It is a flowchart figure which shows an example of the toner replenishment control according to this invention. FIG. 6 is a graph showing an example of a change in the amount of toner in a developing container when toner supply control according to the present invention is performed. It is a schematic sectional drawing of the image forming apparatus which concerns on the other Example of this invention. It is a schematic sectional drawing of an example of a process cartridge. FIG. 10 is a schematic cross-sectional view of another example of a process cartridge and a toner hopper. FIG. 6 is a schematic cross-sectional view of a developing device and a toner hopper for explaining another example of a toner amount detection unit. FIG. 10 is a graph illustrating an example of a change in toner supply amount of a toner hopper when conventional toner supply control is performed. FIG. 10 is a graph showing an example of a change in toner amount in a developing container when conventional toner replenishment control is performed.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Charging roller (charging means)
3 Exposure equipment (exposure means)
4 Developing device (Developing means)
5 Toner hopper (developer supply device)
10 Process cartridge 13 Non-volatile memory (storage device)
14 Nonvolatile memory (storage device)
35 CPU (control device)
36 Nonvolatile memory (storage device)
45 Toner amount detection means 46 Developer container 51 Supply roller (developer supply rotor)

Claims (12)

A developing device for developing the electrostatic image with a developer;
A developer amount detecting device for detecting the developer amount in the developing device;
A developer consumption calculating device for calculating a developer consumption based on image information of the electrostatic image;
A developer supply device for supplying developer to the developing device;
A control device for controlling a developer replenishing operation to the developing device by the developer replenishing device;
In an image forming apparatus having
The control device controls the developer replenishing device to perform a replenishment operation to replenish a predetermined amount of developer each time the developer consumption integrated value obtained by integrating the developer consumption exceeds a replenishment threshold, The replenishment threshold is corrected based on information relating to the developer amount in the developing device detected by the agent amount detection device, and the replenishment threshold is corrected until the replenishment operation is performed a predetermined number of times. There is no image forming apparatus.   The image forming apparatus according to claim 1, wherein the developer consumption amount calculating device is a video count device that calculates a video count number, and calculates the developer consumption amount based on the video count number.   The image forming apparatus according to claim 1, wherein the developer consumption calculating device is a printing rate calculating device that calculates a printing rate, and calculates the developer consumption based on the printing rate.   4. The image forming apparatus according to claim 1, wherein the information on the developer amount is an average value of the developer amount in a predetermined period. When the developer replenishing operation is performed by the developer replenishing device, the replenishment threshold used for comparison with the developer consumption integrated value when the developer replenishing operation is performed is the developer consumption amount. the image forming apparatus according to any one of claims 1 to 4, characterized in that it is subtracted from the integrated value. Each time the developer replenishing operation is performed by the developer replenishing device, the replenishment threshold used for comparison with the developer consumption integrated value is integrated when the developer replenishing operation is performed. the image forming apparatus according to any one of claims 1 to 5 wherein the remaining amount of the developer in the developer supplying apparatus is characterized in that it is detected based on the integrated value. The developer replenishing device includes a developer replenishing rotator that rotates to replenish the developer to the developing device, and the developer replenishing rotator in one developer replenishing operation by the developer replenishing device. the rotation speed, the image forming apparatus according to any one of claims 1 to 6, characterized in that it is determined a predetermined integer rotation. The developing device is removable from the main body of the image forming apparatus, the developing device is provided with a storage device, and the developer consumption integrated value is stored in a storage device provided in the developing device. the image forming apparatus according to any one of claims 1 to 7, characterized in that it is. The developer supply device is detachable from the main body of the image forming apparatus, the developer supply device is provided with a storage device, and the supply threshold is stored in the developer supply device. the image forming apparatus according to any one of claims 1 to 8, characterized in that it is stored in. The developer replenishing device is detachable from the main body of the image forming apparatus, the developer replenishing device is provided with a storage device, and the integrated value of the replenishment threshold is provided in the developer replenishing device. the image forming apparatus according to any one of claims 6 to 9, characterized in that stored in the storage apparatus. The developer developing device used in an image forming apparatus according to any one of claims 1 to 10, characterized in that a one-component developer. It said developer amount detecting apparatus, an image forming apparatus according to any one of claims 1 to 11, characterized in that an optical detection method.

Images