JP5966474B2 - Developer supply apparatus, image forming apparatus, and developer supply control method - Google Patents

Description

  The present invention relates to a developer replenishing device that transports a developer to a developing device and replenishes it, a copier having a developer replenishing device, a printer, a facsimile, and an image forming apparatus such as a multi-function machine having these two or more functions. And a developer replenishment control method.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having two or more of these functions, an electrostatic latent image is formed on the surface of a photoreceptor, and the electrostatic latent image is developed by a developing device. A toner image is formed by attaching toner as a developer to the image, and the toner image is printed on a recording material by transferring and fixing the toner image on a recording paper (paper).

  The developing device consumes developer (toner) in a developing process for visualizing the electrostatic latent image as a toner image. For this reason, the toner is transported from the toner container as the developer container to the developing device according to the amount of toner consumption, and the toner is supplied to the developing device.

  Further, as in Patent Document 1, for example, a toner replenishing device as a developer replenishing device that temporarily transports toner from a toner container (developer container) to a sub hopper as a developer storing unit and replenishes toner from the sub hopper to the developing device. Is widely known between the developer container and the developing device.

  As described above, by having the sub hopper for temporarily storing the toner (developer), it is possible to output a certain number of images even after the toner in the toner container is consumed and emptied. Therefore, even if the toner in the toner container runs out and the toner container needs to be replaced, it is not necessary to replace the toner container immediately, and it can be replaced with a new toner container at a vacant time, so that the downtime of the image forming apparatus can be reduced. It can be shortened.

  Incidentally, in recent years, with the miniaturization of image forming apparatuses such as copiers, the developer storage section (sub hopper) has also been miniaturized. For this reason, the developer capacity temporarily stored in the developer storage section decreases. On the other hand, from the viewpoint of improving the commercial value of an image forming apparatus such as a copying machine, the developer end recovery time (developer concentration when the developer container is replaced) when the developer in the developer container and the developer reservoir is exhausted. The time required for adjustment) is shortened (or omitted) and the remaining amount of developer in the developer container to be replaced is required to be as small as possible.

  However, since the developer capacity in the developer reservoir is decreasing due to the downsizing of the developer reservoir described above, it is difficult to ensure a sufficient recommended replacement period for the developer container. Furthermore, in order to achieve a reduction in the remaining amount of the developer in the developer container when the developer container is replaced, it is desired to take measures such as driving the developer container for a longer time. The time until the determination of near-end (the state in which the developer in the developer container is empty) is confirmed is getting longer.

  In view of such circumstances, in recent image forming apparatuses, it is desired to grasp the amount of developer in the developer reservoir more accurately than in the past, and to make effective use of the developer capacity in the developer reservoir as much as possible. It is coming.

  By the way, in the conventional developer replenishment control, the developer end (printable amount of the image by the developer remaining in the developer reservoir) after the developer near-end is determined as the developer near-end is printed. It is estimated by counting pixels of the image to be determined and determining that a predetermined threshold is exceeded.

  Therefore, in actuality, the developer remaining in the developer storage section from the time when the developer end sensor starts outputting the detection signal in a state where the developer in the developer storage section has decreased to a predetermined lower limit storage amount. Despite the image printing operation being performed, the developer end sensor starts outputting a detection signal indicating that the developer in the developer storage portion has decreased to a predetermined lower limit storage amount, and then the developer near end. In the grasping time (several seconds to several tens of seconds) until it is determined that the amount of developer consumed is not grasped.

  So, for example, there is a solution that can arbitrarily set the amount of developer consumed during the time when it cannot be grasped, and decide the threshold value until the developer end with a margin. It is done. If it is determined that the developer has ended, the printing operation (image forming operation) by the image forming apparatus is automatically stopped.

  However, originally, the developer end sensor prints (images) after it starts outputting the detection signal in a state where the developer in the developer storage portion is reduced to the predetermined lower limit storage amount until it is determined that the developer is near the end. The amount of developer consumed in (formation) greatly depends on the ratio of the image area to the image printable range of the recording paper (hereinafter referred to as “image area ratio”) when the image is printed on the recording paper.

  For this reason, when the image area ratio is small, the amount of developer consumed is smaller than the standard consumption amount, and it is determined that the developer end is left with a sufficient amount of developer remaining in the developer reservoir.

  On the other hand, when the image area ratio is large, the amount of developer consumed is larger than the standard consumption amount. Therefore, before the developer end is determined, the developer in the developer storage unit is emptied and is transferred to the developing device. Developer cannot be replenished. For this reason, inconveniences such as printing an image with a poor density (an image with a low developer density) may occur.

  Therefore, according to the present invention, after the developer near end is determined, even when the image area ratio of the printed image is small or large, the developer in the developer reservoir is substantially empty at the time when the developer end is determined. It is an object of the present invention to provide a developer replenishing device, an image forming apparatus, and a developer replenishment control method that can control developer replenishment.

In order to achieve the above object, a developer replenishing device according to the present invention stores a developer container for storing a developer, a developer supplied from the developer container, and a developer in the developing device. A developer storage unit to be replenished; a remaining amount detection unit for detecting a remaining amount of developer in the developer storage unit; and a control unit for performing developer replenishment control connected to at least the remaining amount detection unit. , based on the detection result from the remaining amount detecting means, the developer supply device for supplying the developer from said developer accommodating vessel to the developer storage portion, said control means, from the remaining amount detecting means Based on the detection result, from the time when it is determined that the remaining amount of developer in the developer reservoir has decreased to a predetermined lower limit amount, the control unit counts up the count value based on the image data input to the exposure apparatus. Start and next When said developer in the developer container is determined to developer near end as a Ryakusora, continues counting up the or sown count value in, Also, the control unit, determines that the developer near end Before the determination, the count value is cleared when it is determined that the remaining amount of the developer in the developer storage unit has recovered to a predetermined upper limit amount based on the detection result from the remaining amount detecting means . .

The image forming apparatus according to the present invention, at least comprising an image forming apparatus and the developing device for current image an electrostatic latent image formed on an image bearing member, to replenish the developer consumed in the developing device A developer replenishing device according to any one of claims 1 to 6 is provided as a developer replenishing device.

The developer replenishment control method according to the present invention includes a developer container for storing a developer, a developer supplied from the developer container, and a developer for supplying the developer to the developing device. The remaining amount using a storage unit, a remaining amount detection unit that detects the remaining amount of developer in the developer storage unit, and a control unit that is connected to at least the remaining amount detection unit and performs developer replenishment control. based on the detection result from the detecting means, the developer supply controlling method for supplying the developer to the developer storage portion from said developer accommodating vessel, said control means, a detection result from said remaining amount detecting means From the time when it is determined that the remaining amount of developer in the developer storage unit has decreased to a predetermined lower limit amount, the control unit starts counting up the count value based on the image data input to the exposure apparatus. And then said When the developer in the image storing container is determined to developer near end as a Ryakusora, continues counting up the or sown count value, also, the control means, prior to determining said developer near end In addition, the count value is cleared when it is determined that the remaining amount of the developer in the developer storage portion has recovered to a predetermined upper limit based on the detection result from the remaining amount detecting means .

According to the developer replenishing device, the image forming apparatus, and the developer replenishing control method according to the present invention, the remaining amount of the developer in the developer storage unit is reduced to the predetermined lower limit amount based on the detection result from the remaining amount detecting unit. From the time point determined to be, the control unit starts counting up the count value based on the image data input to the exposure apparatus, and then determines that the developer in the developer container is almost empty and the developer near end. If, by continuing to count up its or sown count value, it is determined that the developer near end in after determining, even if when the image area ratio of the printed image is small or large, the developer end The developer replenishment control can be performed so that the developer in the developer storage portion becomes almost empty at the time.

1 is a schematic configuration diagram illustrating an image forming apparatus including a toner supply device (developer supply device) according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram illustrating an image forming unit that forms a yellow toner image. 1 is a schematic configuration diagram illustrating a toner supply device (developer supply device) according to an embodiment of the present invention. FIG. 3 is a perspective view showing a toner container storage unit that detachably stores a toner container. FIG. 3 is a diagram illustrating an appearance of a toner container. 6 is a timing chart showing an example of toner supply control by the toner supply device of the embodiment of the present invention. 6 is a timing chart showing an example of toner supply control by the toner supply device of the embodiment of the present invention. 6 is a timing chart showing an example of toner supply control by the toner supply device of the embodiment of the present invention. 6 is a timing chart showing an example of toner supply control in a conventional example (comparative example). 6 is a timing chart showing an example of toner supply control in a conventional example (comparative example). 9 is a timing chart showing an example of toner supply control by the toner supply device of the embodiment of the present invention in a conventional example (comparative example).

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a schematic configuration diagram illustrating an electrophotographic color printer (hereinafter simply referred to as “printer”) as an example of an image forming apparatus including a toner replenishing device as a developer replenishing device according to an embodiment of the present invention. It is. First, the overall configuration and operation of the printer (image forming apparatus) 100 will be described.

(Configuration and operation of printer (image forming apparatus) 100)
As shown in FIG. 1, a printer (image forming apparatus) 100 according to the present embodiment is provided with a toner container storage unit 31 and toner replenishing devices 60Y, 60M, 60C, and 60K, which will be described later, in the upper part of the apparatus main body 110. . In the toner container housing portion 31, toner containers (toner bottles) 32Y, 32M, 32C as four developer containers each containing toner as a developer of each color (yellow, magenta, cyan, black) are stored. 32K is detachably (replaceable). Toner supply devices 60Y, 60M, 60C, and 60K are provided so as to correspond to the toner containers 32Y, 32M, 32C, and 32K, respectively.

  An intermediate transfer unit 15 and four image forming units 6Y, 6M, 6C, and 6K are disposed below the toner container housing unit 31 in the apparatus main body 110. The configurations of the image forming units 6Y, 6M, 6C, and 6K that respectively create a yellow toner image, a magenta toner image, a cyan toner image, and a black (black) toner image are basically the same. The configuration and operation of the image forming unit 6Y will be described.

  As shown in FIG. 2, the image forming unit 6Y that forms a yellow toner image includes a photosensitive drum 1Y, a charging roller 4Y disposed around the photosensitive drum 1Y, a developing device 5Y, and a cleaning device 2Y. And a static eliminator (not shown). In the image forming section 6Y, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1Y to form a yellow image (yellow toner image). .

  The photosensitive drum 1Y is rotationally driven in a clockwise direction as viewed from the front in FIG. 2 by a drive motor (not shown). The surface of the photosensitive drum 1Y is uniformly charged by the charging roller 4Y that is in contact (charging process). Thereafter, the surface of the photosensitive drum 1Y reaches the irradiation position of the laser beam L emitted from the exposure device 7 (see FIG. 1), and an electrostatic latent image corresponding to yellow is formed by exposure scanning at that position. (Exposure process).

  Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the developing device 5Y, and the electrostatic latent image is developed (visualized) at the facing position to form a yellow toner image (developing step). ). Thereafter, when the surface of the photosensitive drum 1Y reaches a position facing the intermediate transfer belt 8 and the primary transfer bias roller 9Y, the toner image on the photosensitive drum 1Y is transferred onto the intermediate transfer belt 8 at that position. (Primary transfer step).

  Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the cleaning device 2Y, and untransferred toner remaining at the position is mechanically collected by the cleaning blade 2a (cleaning step). The surface of the photosensitive drum 1Y reaches a position facing a static eliminator (not shown), and the residual potential is removed at that position. Thereby, a series of image forming processes performed on the photosensitive drum 1Y (surface) is completed.

  This series of image forming processes is performed in the same manner in the other three image forming units 6M, 6C, and 6K. For the image forming process in each of the image forming units, the exposure apparatus 7 emits a laser beam L from a light source based on input image information and rotates the laser beam L, although not shown. And irradiating the photosensitive drums 1Y, 1M, 1C, and 1K through a plurality of optical elements.

  Here, in the intermediate transfer unit 15, four primary transfer bias rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 with the corresponding photosensitive drums 1Y, 1M, 1C, and 1K, and perform the primary. A transfer nip is formed. Each primary transfer bias roller 9Y, 9M, 9C, 9K is applied with a transfer bias opposite to the polarity of the toner. Therefore, the intermediate transfer belt 8 moves in the direction of the arrow, and sequentially passes through the primary transfer nips by the primary transfer bias rollers 9Y, 9M, 9C, and 9K and the photosensitive drums 1Y, 1M, 1C, and 1K. The toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred onto the intermediate transfer belt 8 so as to overlap each other. As a result, a color image is formed on the intermediate transfer belt 8.

  Thereafter, a portion where the toner images of the respective colors on the intermediate transfer belt 8 are transferred in a superimposed manner (a portion where a color image is formed) reaches a position facing the secondary transfer roller 19. At this facing position, the secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 with the secondary transfer roller 19 to form a secondary transfer nip. For this reason, the toner image (color image) formed on the intermediate transfer belt 8 is transferred onto a recording medium P such as paper conveyed to the position of the secondary transfer nip.

  Thereafter, the portion of the intermediate transfer belt 8 where the untransferred toner remains reaches the position where the intermediate transfer cleaning member 10 is provided. At this position, the untransferred toner on the intermediate transfer belt 8 is collected by the intermediate transfer cleaning member 10. Thus, a series of transfer processes performed on the intermediate transfer belt 8 is completed.

  Here, the recording medium (paper) P transported to the position of the secondary transfer nip passes from the paper feeding unit 26 provided at the lower part in the apparatus main body 110 via the paper feeding roller 27 and the registration roller pair 28. Are transported. A plurality of recording media P such as paper are stacked and stored in the paper supply unit 26. In the paper feeding unit 26, the paper feeding roller 27 is driven to rotate counterclockwise when viewed from the front in FIG. 2, so that the uppermost recording medium P stored is placed between the rollers of the registration roller pair 28. It is sent toward. The registration roller pair 28 temporarily stops the recording medium P conveyed by stopping the rotation driving at the position of the roller nip.

  Thereafter, the registration roller pair 28 is rotationally driven in synchronization with the passage of the portion where the color image is formed on the intermediate transfer belt 8 that is moved endlessly, and conveys the recording medium P toward the secondary transfer nip. Thereby, a desired color image is transferred onto the recording medium P.

  Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing device 20. In the fixing device 20, the color image transferred onto the surface is fixed on the recording medium P by heat and pressure generated by the fixing roller 20 a and the pressure roller 20 b. Thereafter, the recording medium P is discharged to the upper surface of the apparatus main body 110 through the rollers of the paper discharge roller pair 29.

  The recording media P discharged by the discharge roller pair 29 are sequentially stacked (stacked) on the stack unit 30 as a print image. Thereby, a series of image forming processes in the printer 100 is completed.

(Configuration and operation of developing device 5Y)
The configurations of the developing devices 5Y, 5M, 5C, and 5K (see FIG. 1) of the image forming units 6Y, 6M, 6C, and 6K are basically the same as those of the developing devices 5Y. This will be described with reference to FIG.

  As shown in FIG. 2, the developing device 5Y of the image forming unit 6Y includes a developing roller 51Y that faces the photosensitive drum 1Y, a doctor blade 52Y that faces the developing roller 51Y, and a first developer container that stores developer G. 53Y, a second developer accommodating portion 54Y, two conveying screws 55Y disposed therein, and a toner concentration detection sensor 56Y for detecting the toner concentration in the developer G. The developer G accommodated in the first developer accommodating portion 53Y and the second developer accommodating portion 54Y is a two-component developer composed of a carrier and toner. As the developer, for example, a one-component developer or a developer in which a carrier and a toner are premixed may be used, and can be appropriately selected according to the type of the developing device to be used.

  Although not shown, the developing roller 51Y includes a magnet fixed inside and a sleeve that rotates around the magnet. A toner supply pipe 57Y is connected to the upper part of the developer containing portion 54Y. The toner replenishment tube 57Y is connected to a sub hopper 65 as a developer storage section of a toner replenishing device 60Y (see FIG. 3), which will be described later, and the ratio (toner concentration) of toner in the developer G in the developing device 5Y. The toner t is appropriately supplied from the sub hopper 65 through the toner supply pipe 57Y into the developer accommodating portion 54Y so as to be within a predetermined range.

  The developing device 5Y operates as follows. The toner t replenished into the second developer accommodating portion 54Y from the sub hopper 65 through the connecting pipe 57Y is mixed with the carrier by the two conveying screws 55Y and stirred while being mixed along the longitudinal direction of each conveying screw 55Y. It is configured to circulate between the developer accommodating portion 53Y and the second developer accommodating portion 54Y. The developer G in the first developer accommodating portion 53Y is supplied and carried on the sleeve surface of the developing roller 51Y by the magnetic field formed by the magnet roller in the developing roller 51Y while being conveyed to one side of the conveying screw 55Y. The

  The sleeve of the developing roller 51Y is rotationally driven in the direction of the arrow (counterclockwise), and the developer G carried on the developing roller 51Y moves on the developing roller 51Y as the sleeve rotates. At this time, the toner in the developer G is charged on the potential opposite to that of the carrier due to frictional charging with the carrier in the developer G, and is electrostatically attracted to the carrier, and is formed on the developing roller 51Y. Along with the carrier attracted by the magnetic field, it is carried on the developing roller 51Y.

  The developer G carried on the developing roller 51Y is conveyed in the direction of the arrow (counterclockwise), and reaches the doctor portion where the doctor blade 52Y and the developing roller 51Y face each other. The amount of the developer G on the developing roller 51Y is adjusted to an appropriate amount when passing through the doctor portion, and is then conveyed to the developing region that is the position facing the photosensitive drum 1Y. In the developing area, the toner in the developer G is attracted to the electrostatic latent image formed on the photosensitive drum 1Y by the developing electric field formed between the developing roller 51Y and the photosensitive drum 1Y. The developer G remaining on the surface of the developing roller 51Y that has passed through the developing region reaches above the first developer containing portion 53Y as the sleeve rotates, and is detached from the developing roller 51Y at this position.

  The developer G in the developing device 5Y is adjusted so that the toner density is within a predetermined range. Specifically, toner is replenished into the second developer accommodating portion 54Y from a toner replenishing device 60Y, which will be described later, through a toner replenishing tube 57Y in accordance with the consumption amount of toner contained in the developer G in the developing device 5Y. . The toner replenished in the second developer accommodating portion 54Y is mixed and stirred together with the developer G by the two developer conveying screws 55Y, while being mixed between the first developer accommodating portion 53Y and the second developer accommodating portion 54Y. Circulate between them.

(Configuration and operation of toner replenishing device 60Y)
The configurations of the toner supply devices 60Y, 60M, 60C, and 60K provided corresponding to the toner containers 32Y, 32M, 32C, and 32K are basically the same as those of the toner supply devices 60Y, 32M, 32C, and 32K. Will be described with reference to FIG.

  FIG. 3 is a diagram showing a schematic configuration of the toner replenishing device 60Y. As shown in FIG. 3, the toner replenishing device 60Y includes a toner container rotation drive motor 61 that rotates a substantially cylindrical toner container 32Y mounted on the toner container mounting portion 33Y, and a toner discharge port 34Y of the toner container mounting portion 33Y. The screw pump 63 that sucks toner from the first toner transport pipe 62 and the toner sucked by the screw pump 63 are temporarily stored through the second toner transport pipe 64 and then the developing device 5Y (second developer container 54Y). And a control unit 66 for controlling the entire toner supply operation. Details of the control of the toner replenishment operation by the controller 66 will be described later.

  As shown in FIGS. 3 and 4, a toner container mounting portion 33Y is provided on one end side of the toner container storage portion 31 to which the toner container 32Y is detachably mounted. A cup of the toner container mounting portion 33Y is provided. The attachment side end portion 32Ya of the toner container 32Y is connected to the ring portion 35Y. The mounting side end portions of the other toner containers 32M, 32C, and 32K are similarly connected to the coupling portion.

  As shown in FIG. 5, the toner container 32Y has a spiral protrusion 32Yb formed on the inner peripheral surface along the longitudinal direction thereof, and the toner accommodated therein is spirally formed by the rotation of the toner container 32Y itself. By the groove 32Yb, the toner container 32Y is conveyed to the mounting side end 32Ya side (right side in FIGS. 3 and 5).

  The toner container mounting portion 33Y is provided with a toner container rotation driving mechanism including a toner container rotation driving motor 61, and the toner container mounting portion 33Y has a coupling portion 35Y (see FIG. 4) mounted on the mounting side end of the toner container 32Y. The unit 32 </ b> Ya is connected, and the toner container 32 </ b> Y is configured to rotate in the toner container storage unit 31 by driving the toner container rotation drive motor 61.

  The tip opening of the mounting side end 32Ya of the toner container 32Y is sealed with a plug member 32Yc having an opening / closing part (not shown). On the other hand, the toner container mounting portion 33Y has an opening / closing drive mechanism (including a drive motor for mechanically opening an opening / closing portion (not shown) of the plug member 32Yc when the toner container 32Y is mounted in the toner container storage portion 31). (Not shown) is provided. Thus, when the toner container 32Y is mounted in the toner container storage portion 31, the opening / closing portion (not shown) of the plug member 32Yc is opened by driving of the opening / closing drive mechanism (not shown) of the toner container mounting portion 33Y. And the toner discharge port 34Y below the toner container mounting portion 33Y communicate with each other.

  The screw pump 63 is a suction type uniaxial eccentric screw pump, and includes a stator 70, a rotor 71, a suction port 72, a universal joint 73, and a pump drive motor 74.

  The stator 70 is an internally threaded member made of an elastic material such as rubber, and a double pitch spiral groove is formed on the inner wall surface thereof. The rotor 71 is a male screw-like member formed by spirally twisting a shaft made of a rigid material such as metal, and is inserted into the stator 70 so as to be rotatable. One end of the rotor 71 is rotatably connected to a pump drive motor 74 via a universal joint 73.

  This screw pump 63 rotates the rotor 71 in the stator 70 in a predetermined direction by a pump drive motor 74, thereby sending air in the first toner transport pipe 62 and negative pressure in the first toner transport pipe 62. And a suction force is generated at the suction port 72. As a result, the toner (yellow toner) in the toner container 32Y is sucked into the suction port 72 through the first toner transport tube 62 together with air. The toner sucked up to the suction port 72 is fed into the gap between the stator 70 and the rotor 71, and is sent to the other end side (the side opposite to the suction port 72) of the stator 70 along the rotation of the rotor 71. The sent toner is transported from the toner discharge port 75 to the sub hopper 65 through the second toner transport pipe 64.

  The sub hopper 65 conveys the toner to the toner discharge port side communicating with the toner supply pipe 57Y while agitating the toner, the conveyance screw rotation drive mechanism including the conveyance screw rotation drive motor 77, and the amount of toner in the sub hopper 65. A toner amount detection sensor 78 for detection is provided.

  When the control unit 66 determines that the toner concentration in the developer G in the developing device 5Y is equal to or lower than the set concentration based on the detection signal input from the toner concentration detection sensor 56Y during the image forming process described above. A drive signal is output to the conveyance screw rotation drive motor 77 to rotate the conveyance screw 76, and the toner is supplied from the sub hopper 65 through the toner supply pipe 57Y to the developing device 5Y (second developer accommodating portion 54Y).

  When the controller 66 determines that the toner in the sub hopper 65 has decreased to a predetermined lower limit storage amount based on the detection signal input from the toner amount detection sensor 78, the toner container rotation drive motor 61 and the pump drive motor The drive signal is output to 74 to rotate the toner container 32Y and the rotor 71 of the screw pump 63, and the toner is fed into the sub hopper 65 from the toner container 32Y through the first toner transport pipe 62, the screw pump 63, and the second toner transport pipe 64. To supply.

  In such a toner supply operation to the sub hopper 65, the toner in the sub hopper 65 has a predetermined lower limit storage amount even if a predetermined time has elapsed even though the toner supply operation from the toner container 32Y to the sub hopper 65 is performed. When the control unit 66 detects that the toner amount has not increased from the predetermined lower limit storage amount or further decreased from the predetermined lower limit storage amount based on the detection signal input from the toner amount detection sensor 78, the control unit 66 is in the toner container 32Y. Is determined to be empty (hereinafter, the state in which it is determined that the toner in the toner container 32Y is empty is referred to as “toner near end”).

  As described above, there is a predetermined time lag from when the toner in the toner container 32Y is actually emptied until it is determined that the toner is near the end. Note that when the toner near-end is determined, a predetermined amount of toner remains in the sub hopper 65 although it is the lower limit storage amount or the lower limit storage amount or less.

  After the toner near-end is determined, the toner remaining in the sub hopper 65 is supplied to the developing device 5Y (second developer accommodating portion 54Y). Then, the control unit 66 increments the count value of the number of pixels of the entire image to be printed (image formation) (the total number of dots included in the entire image), and determines that the toner end is reached when a predetermined threshold value is exceeded. To do. If it is determined that the toner end is reached, the recording medium (paper) is stopped (the above-described image forming process is stopped). The number of pixels of the entire printed image can be grasped based on, for example, image data input to the exposure device 7.

  Note that the control unit 66 selects one of the number of pixels of the entire image to be printed (image formation) (the total number of dots included in the entire image), the number of printed sheets, and the toner replenishment drive time from the sub hopper 65 to the developing device 5Y. A control count value corresponding to one or a control count value corresponding to any two or more is counted up, and it is determined that the toner end is reached when the integrated count value exceeds a predetermined threshold value. Good.

(Toner replenishment control of toner replenishing device 60Y in this embodiment)
The toner replenishment control of the toner replenishing devices 60Y, 60M, 60C, and 60K in the present embodiment is basically the same, so the toner replenishing control of the toner replenishing device 60Y described above will be described with reference to FIGS. explain. 9 to 11 are timing charts showing toner supply control in the conventional example (comparative example).

  FIG. 6 is a timing chart of the toner replenishment control when the image area ratio (the ratio of the image area to the recording medium (paper)) is 30%. The “image area ratio”, “toner container toner amount”, “ This shows a time-series situation of “amount of toner in sub hopper”, “toner near end / end determination state”, and “pixel count value”. The same applies to FIGS. 7 to 11 below.

  In FIG. 6, “a1” in “sub-hopper toner amount” is the upper toner storage amount, “a2” is the lower toner storage amount, and “toner near end / end determination state” b1 is the toner full determination state (the toner in the sub hopper 65 has a lower limit). B2 is a toner near-end determination state, b3 is a toner-end determination state, S of “pixel count value” is a preset threshold value, and the same applies to FIGS.

  As shown in FIG. 6, when the above-described image forming process is started from time t1, the control unit 66 controls the content of the developer G in the developing device 5Y based on the detection signal input from the toner density detection sensor 56Y. When it is determined that the toner density is equal to or lower than the set density, as described above, a driving signal is output to the conveying screw rotation driving motor 77 of the sub hopper 65 to rotate the conveying screw 76, and the toner is supplied from the sub hopper 65 to the developing device 5Y ( The second developer container 54Y) is replenished.

  When the controller 66 determines that the toner in the sub hopper 65 has decreased from the upper limit storage amount a1 to the lower limit storage amount a2 based on the detection signal input from the toner amount detection sensor 78, as described above. A drive signal is output to the container rotation drive motor 61 and the pump drive motor 74 to rotate the toner container 32Y and the rotor 71, and supply the toner from the toner container 32Y into the sub hopper 65. Thereby, the toner in the sub hopper 65 is restored to the upper limit storage amount a1.

  Thus, between time t1 and time t3, the toner in the sub hopper 65 is kept between the upper limit storage amount a1 and the lower limit storage amount a2. On the other hand, since the toner in the toner container 32Y decreases with supply to the sub hopper 65 and becomes empty at time t2, the toner in the sub hopper 65 does not increase from the lower limit storage amount a2 at time t3.

  In the toner replenishment control of the present embodiment, the control unit 66 counts the number of pixels (pixel count) of an image to be printed (image formation) when it is determined that the toner in the sub hopper 65 has decreased to the lower limit storage amount a2. Value) is counted up, and the pixel count value is cleared (reset) when it is determined that the toner in the sub hopper 65 has recovered to the upper limit storage amount a1. Between time t1 and time t3, it is cleared (reset) before reaching a preset threshold value S.

  Then, after determining that the toner has decreased to the lower limit storage amount a2 at time t3, the control unit 66 determines that the toner is near end at time t4. When the pixel count value counted up from time t3 reaches the threshold value S at time t5, the toner end b3 is determined, and the above-described image forming process is stopped (device stop).

  The pixel count value is counted according to the image area ratio. That is, the smaller the image area ratio, the smaller the count-up number of the pixel count value, and the larger the image area ratio, the larger the count-up number of the pixel count value.

  FIG. 7 illustrates a case where an image with an image area ratio of 80% is printed between time t3 and time t4 (between the determination that the toner has decreased to the lower limit storage amount a2 and the determination that the toner is near the end). 6 is a timing chart of a toner supply control operation. Note that an image with an image area ratio of 30% is printed between time t1 and time t3 and between time t4 and time t5, as in FIG.

  The toner replenishment control between time t1 and time t3 is the same as in the case of FIG. Then, after determining that the toner has decreased to the lower limit storage amount a2 at time t3, it is determined that the toner is near end at time t4. At this time, the pixel count value corresponding to image printing with an image area of 80% is counted up from time t3.

  Then, when image printing with an image area of 30% is performed from time t4, the pixel count value corresponding to the image printing with an image area of 30% is counted up from time t4 (in the case of image printing with an image area of 80%) Count up more slowly). When the pixel count value counted up from time t3 reaches the threshold value S at time t5, the toner end b3 is determined, and the above-described image forming process is stopped (device stop).

  FIG. 8 shows a case where an image with an image area ratio of 1% is printed between time t3 and time t4 (between the determination that the toner has decreased to the lower limit storage amount a2 and the determination that the toner is near the end). 6 is a timing chart of toner supply control. Note that an image with an image area ratio of 30% is printed between time t1 and time t3 and between time t4 and time t5, as in FIG.

  The toner replenishment control between time t1 and time t3 is the same as in the case of FIG. Then, after determining that the toner has decreased to the lower limit storage amount a2 at time t3, it is determined that the toner is near end at time t4. At this time, the pixel count value corresponding to the image printing with the image area of 1% is counted up from the time t3 (in the image printing with the image area of 1%, the pixel count value is slightly increased).

  Then, when image printing with an image area of 30% is performed from time t4, the pixel count value corresponding to the image printing with an image area of 30% is counted up from time t4. When the pixel count value counted up from time t3 reaches the threshold value S at time t5, the toner end b3 is determined, and the above-described image forming process is stopped (device stop).

  As described above, in the toner replenishment control according to the embodiment of the present invention, the pixel count value is set every time when it is determined that the toner in the sub hopper 65 has decreased to the lower limit storage amount based on the detection signal from the toner amount detection sensor 78. The pixel count value is cleared and the pixel count value is cleared (reset) when it is determined that the toner has recovered to the upper limit storage amount.

  Then, after determining that the toner has decreased to the lower limit storage amount a2, if the pixel count value is counted up according to the image area ratio and reaches a predetermined threshold value S, it is determined that the toner has ended and the image forming process is performed. Is controlled to stop (device stop). As a result, an image in which the image area ratio is changed is printed between the time when it is determined that the toner in the sub hopper 65 has decreased to the lower limit storage amount and the time when the toner near-end is determined (between time t3 and time t4). Even in this case, the time when the toner in the sub hopper 65 becomes almost empty and the toner is no longer supplied to the developing device 5Y and the time when the pixel count value reaches the predetermined threshold S and is determined to be the toner end are substantially the same. It becomes possible to set as follows.

  Note that the percentage (%) of the image area ratio in the toner replenishment control in FIGS. 6 to 8 is merely an example, and it is needless to say that the present invention can be similarly applied to any image area ratio.

(Toner supply control of toner supply device in conventional example (comparative example))
9 to 11 are timing charts showing the toner replenishment control operations of Conventional Examples 1 to 3. FIG.

  In Conventional Example 1 shown in FIG. 9, toner supply control between time t1 and time t3 is the same as in FIG. 6 (when the image area ratio is 30%). Then, after determining that the toner has decreased to the lower limit storage amount a2 at time t3, it is determined that the toner is near end at time t4. At this time, the pixel count value corresponding to image printing with an image area of 30% is counted up from time t4.

  In this conventional example 1, the time when the toner in the sub hopper 65 becomes substantially empty after it is determined that the toner has decreased to the lower limit storage amount a2 at time t3, and the time when the toner near end is determined at time t4 is counted up. The threshold value of the pixel count value (hereinafter referred to as “setting threshold value”) Sa is set in advance so that the time until the count value of the pixel count value reaches the threshold value is substantially the same. This setting threshold value Sa is the same value in the following conventional examples 2 and 3.

  When the pixel count value counted up from time t4 reaches the set threshold value Sa at time t5, the toner end b3 is determined, and the above-described image forming process is stopped (device stop).

  Conventional example 2 shown in FIG. 10 has an image area ratio of 80% between time t3 and time t4 (between the determination that the toner has decreased to the lower limit storage amount a2 and the determination that the toner is near the end). 6 is a timing chart of a toner replenishment control operation when printing is performed. Note that during time t1 to time t3 and between time t4 and time t5, an image is printed with an image area ratio of 30%.

  The toner replenishment control between time t1 and time t3 is the same as in the case of FIG. Then, after determining that the toner has decreased to the lower limit storage amount a2 at time t3, it is determined that the toner is near end at time t4. At this time, the pixel count value is counted up from time t4.

  Between time t3 and time t4, an image is printed at an image area ratio of 80%, so that the toner consumption is large. For this reason, even if the toner in the sub hopper 65 becomes empty at time t4a, the pixel count value counted up from time t4 has not yet reached the set threshold value Sa, and the image forming process is continued. When the pixel count value reaches the set threshold value Sa at time t5, the toner end b3 is determined, and the image forming process is stopped (device stop).

  As described above, in the conventional example 2 shown in FIG. 10, for example, the image area ratio during the period from the time t3 to the time t4 (between the determination that the toner has decreased to the lower limit storage amount a2 and the determination that the toner is near the end). When 80% of the image is printed, the toner in the sub hopper 65 is emptied before the end of the toner is determined, so that the toner supply to the developing device 5Y (5M, 5C, 5K) is insufficient. An abnormal image is output due to a decrease in toner density.

  Conventional example 3 shown in FIG. 11 has an image area ratio of 1% between time t3 and time t4 (between the determination that the toner has decreased to the lower limit storage amount a2 and the determination that the toner is near the end). 6 is a timing chart of toner replenishment control when printing is performed. Note that during time t1 to time t3 and between time t4 and time t5, an image is printed with an image area ratio of 30%.

  The toner replenishment control between time t1 and time t3 is the same as in the case of FIG. Then, after determining that the toner has decreased to the lower limit storage amount a2 at time t3, it is determined that the toner is near end at time t4. At this time, the pixel count value is counted up from time t4.

  At this time, between time t3 and time t4, an image is printed with an image area ratio of 1%, so that toner consumption is small. For this reason, even when the pixel count value reaches the set threshold value Sa at time t5, it is determined that the toner has ended, and the image forming process is stopped (the apparatus is stopped), the toner still remains in the sub hopper 65 by a predetermined amount a3.

  As described above, in the conventional example 3 shown in FIG. 11, for example, the ratio of the image area between time t3 and time t4 (between the determination that the toner has decreased to the lower limit storage amount a2 and the determination that the toner is near the end). When 1% of the image is printed, even if it is determined that the toner has ended, a predetermined amount of toner still remains in the sub hopper 65, and the toner replenishment capability of the sub hopper 65 cannot be utilized to the maximum.

  On the other hand, in the toner replenishment control in the above-described embodiment of the present invention, after the toner near end is determined, even when the image area ratio of the image to be printed is small or large, at the time when the toner end is determined. Since the toner replenishment control can be performed so that the toner in the sub hopper 65 becomes substantially empty, the toner replenishment ability of the sub hopper 65 can be utilized to the maximum, and an image with a proper toner density is printed to the end. Is possible.

5Y, 5M, 5C, 5K Developing device 31 Toner container container 32Y, 32M, 32C, 32K Toner container (developer container)
56Y Toner density detection sensor (density detection means)
60Y, 60M, 60C, 60K Toner replenishing device 61 Toner container rotation drive motor 63 Screw pump 65 Sub hopper (developer reservoir)
66 Controller 74 Pump drive motor 77 Conveying screw rotation drive motor 78 Toner amount detection sensor (remaining amount detection means)
100 printer (image forming apparatus)

JP 2007-114429 A

Claims (8)

A developer container for storing the developer;
A developer storage unit that stores the developer supplied from the developer container and replenishes the developer to the developer;
A remaining amount detecting means for detecting the remaining amount of the developer in the developer storing section;
Control means connected to at least the remaining amount detection means for performing developer replenishment control,
Based on the detection result from the remaining amount detecting means, the developer supplying apparatus for supplying a developer to the developer storage portion from said developer accommodating vessel,
The control means inputs to the exposure apparatus of the control means from the time when it is determined that the remaining amount of the developer in the developer reservoir is reduced to a predetermined lower limit amount based on the detection result from the remaining amount detection means. and starts counting up the count value based on the image data, and then when the developer in the developer container is determined to developer near end as a Ryakusora, the count-up of the or sown count value Continue ,
Further, before determining that the developer is near the end, the control unit determines that the remaining amount of developer in the developer storage unit has recovered to a predetermined upper limit based on the detection result from the remaining amount detecting unit. In this case, the developer replenishing device is characterized in that the count value is cleared . The developer supply device according to claim 1,
It said control means, after determining that the developer near end, when Luke count value has been counted up continuously exceeds a predetermined threshold value, the developer of the developer storing portion is Ryakusora development A developer replenishing device characterized in that the developer end is determined. The developer replenishing device according to claim 1 or 2 ,
Before asked count value, said with corresponding developer remaining amount, the developer supply device, characterized in that the control value based on at least one of the number of pixels and the number of printed sheets of the entire image. The developer replenishing device according to claim 1 or 2 ,
A developer replenishing means for replenishing the developer from the developer reservoir to the developing device;
The developer supply device, wherein the control means controls the developer supply means so as to supply the developer to the developing device. The developer replenishing device according to claim 4 .
A density detecting means for detecting the density of the developer in the developing device;
The developer supply device according to claim 1, wherein the control unit performs control to supply the developer in the developer storage unit to the development device based on a detection result from the density detection unit. The developer replenishing device according to claim 4 or 5 ,
Prior ask count value, with corresponding to the remaining developer, wherein the number of pixels of the entire image, number of prints, and in that the a control value based on at least one of operation time of the developer supply unit Developer replenishing device. In at least comprising an image forming apparatus and the developing device for current image an electrostatic latent image formed on an image bearing member,
Wherein as the developer replenishing device for replenishing the developer consumed in the developing device, an image forming apparatus characterized by comprising a developer replenishing device according to any one of claims 1-6. A developer container for storing the developer, a developer reservoir for storing the developer supplied from the developer container, and replenishing the developer to the developing device, and a developer residue in the developer reservoir Using a remaining amount detecting means for detecting the amount, and a control means for performing developer replenishment control connected to at least the remaining amount detecting means,
Based on the detection result from the remaining amount detecting means, the developer supply controlling method for supplying the developer from said developer accommodating vessel to the developer storage portion,
From the time when the control unit determines that the remaining amount of developer in the developer storage unit has decreased to a predetermined lower limit amount based on the detection result from the remaining amount detection unit, the control unit inputs to the exposure apparatus. and starts counting up the count value based on the image data, and then when the developer in the developer container is determined to developer near end as a Ryakusora, the count-up of the or sown count value Continue ,
Further, before determining that the developer is near the end, the control unit determines that the remaining amount of developer in the developer storage unit has recovered to a predetermined upper limit based on the detection result from the remaining amount detecting unit. In this case, the developer replenishment control method is characterized in that the count value is cleared .