JP2008299260A - Toner container, and image forming device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner container that can accurately supply the required quantity of toner without much variation in both large quantity supply and trace quantity supply. <P>SOLUTION: The toner container 21 stores toner inside and conveys the toner to a toner supply port 34 by a toner transport screw 33 rotationally driven by a toner supply motor 35. The diameter of the toner transport screw 33 is changed at the toner supply port 34 as a boundary and composed of a large diameter part 33A and a small diameter part 33B, and the toner supply motor 35 is normally or reversely rotated according to the supply quantity of toner. The normal and reverse rotation of the toner transport screw 33 is switched based on a printing rate. Further, the toner supply port 34 is arranged in a position offset to the small diameter part 33B side from the axial center of the transport screw 33. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a toner container for supplying toner to a developing device and an image forming apparatus including the toner container.

  In an image forming apparatus such as a copying machine or a printer that adopts an electrophotographic system, an electrostatic latent image formed on an image carrier such as a photosensitive drum is developed with toner as a developer in a developing device. There is known an image forming apparatus that employs a system that replenishes toner from a toner container when the image forming operation is repeated and the remaining amount of toner in the developing device is reduced. Patent Document 1).

  Here, the toner container is detachably attached to the developing device or the image forming apparatus main body, conveys the toner to the toner replenishing port by a toner conveying screw that is rotationally driven by the toner replenishing motor, and the toner from the toner replenishing port to the developing device. To replenish.

  By the way, in Patent Document 2, particularly in a toner container that replenishes toner to a developing device using a two-component developer having toner and a carrier, the rotation time of the toner conveying screw is kept constant, and the number of rotations is made variable. There has been proposed a technique for keeping the developer concentration uniform by increasing the stirring speed of the supplied toner and the developer by supplying the toner.

Further, in Patent Document 3, in a developing device using a two-component developer, a toner concentration sensor for detecting the toner concentration based on the magnetic permeability of the developer is provided in the vicinity of the toner conveying screw in the agitating chamber, while the developer is agitated. By disposing the developer at a constant flow rate on the detection surface of the density sensor and providing a regular flow of the developer, an accurate toner concentration can be obtained regardless of the fluctuation of the developer bulk density. A developing device that performs control has been proposed.
JP 2006-284661 A Japanese Unexamined Patent Publication No. 7-084448 JP 2003-307918 A

  By the way, with the recent increase in printing speed of image forming apparatuses, the amount of toner required for high density printing increases, so the outer diameter of the toner conveying screw of the toner container tends to increase.

  Thus, although the toner conveying screw has a high toner conveying ability, the toner conveying amount pulsates in detail due to the influence of its own screw rib. For this reason, when a small amount of toner with a low printing rate is supplied, there is a problem that one operation of the toner conveying screw becomes one rotation or less, resulting in a large variation in the amount of toner supply.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner container capable of accurately replenishing a required amount of toner without large variation even when supplying a large amount or a small amount of replenishment. An object is to provide an image forming apparatus.

  In order to achieve the above object, the invention according to claim 1 is a toner container for storing toner therein and transporting the toner to a toner replenishing port by a toner transporting screw rotated by a toner replenishing motor. The diameter of the toner is changed with the toner replenishing port as a boundary, and the toner replenishing motor is rotated forward and backward according to the toner replenishing amount.

  According to a second aspect of the present invention, in the first aspect, the forward / reverse switching of the toner conveying screw is performed based on a printing rate.

  A third aspect of the invention is characterized in that, in the first or second aspect of the invention, the toner replenishing port is disposed at a position offset to the smaller diameter side from the axial center of the conveying screw.

  According to a fourth aspect of the invention, the image forming apparatus includes the toner container according to any one of the first to third aspects.

  According to the first aspect of the present invention, the diameter of the toner conveying screw is changed with the toner replenishing port as a boundary, and the toner replenishing motor is rotated in the forward and reverse directions according to the toner replenishing amount. A large amount of toner can be conveyed to the toner supply port by the side and supplied to the developing device. Further, when supplying a small amount, the toner conveying screw can be rotated in the opposite direction to that when supplying a large amount, and a small amount of toner can be conveyed to the toner replenishing port on the small diameter side of the toner conveying screw and replenished to the developing device. In this way, since a small amount of toner is conveyed on the small diameter side of the toner conveying screw, one operation of the toner conveying screw does not become one rotation or less, and even when a small amount of toner is replenished, the toner conveying screw. Rotates a plurality of times so that there is no large variation in the replenishment amount.

  Therefore, the required amount of toner can be accurately replenished without large variation even when supplying a large amount or a small amount.

  According to the second aspect of the present invention, since the toner replenishment amount to the developing device is proportional to the printing rate of the paper, the forward / reverse switching of the toner conveying screw is performed according to this printing rate, and the printing rate is below a predetermined value. In this case, a small amount of toner can be conveyed on the small diameter side of the toner conveying screw.

  According to the third aspect of the present invention, since the toner replenishing port is disposed at a position offset to the small diameter side from the axial center of the toner conveying screw, the toner conveying screw is moved in the direction opposite to the toner replenishing port by the large diameter side of the toner conveying screw. The transport distance of a large amount of toner to be transported becomes long, and the toner container is prevented from being blocked by the large amount of toner.

  According to the fourth aspect of the present invention, since a necessary amount of toner is accurately replenished to the developing device without a large variation by the toner container, a toner image having a predetermined density can be stably obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
[Image forming apparatus]
FIG. 1 is a side sectional view of a laser beam printer as an embodiment of an image forming apparatus according to the present invention.

  In the illustrated laser beam printer 1, an inclined concave discharge tray 3 is provided at the center of the upper surface of a box-shaped main body (housing) 2. An openable and closable manual feed tray 4 is provided at the upper part of the front surface of the main body 2 (the right side in FIG. 1 is the front), and the manual feed paper that is rotatably provided in the manual feed tray 4 and the main body 2 at the back thereof. The roller 5 constitutes a manual sheet feeding unit 6. Thus, the laser beam printer 1 conveys an image on a sheet based on image data transmitted from a terminal (not shown) while conveying a sheet as a recording material along a conveyance path L provided in the main body 2. The conveyance path L is substantially L-shaped in a side view and extends to the paper discharge tray 3.

  The laser beam printer 1 includes a cassette paper feeding unit 7 provided at the lower part of the main body 2, an image forming unit 8 provided at a substantially central portion in the main body 2 above the cassette paper feeding unit 7, and the image A fixing unit 9 disposed behind the forming unit 8 and a concave paper discharge unit 10 provided on the upper surface of the main body 2 above the fixing unit 9 are provided.

  The cassette sheet feeding unit 7 stacks and stores a plurality of sheets in a rectangular box-shaped sheet feeding cassette 11 having an open top surface, and picks a roller 12 that takes out the sheets in the sheet feeding cassette 11 one by one. A pair of cassette paper feed rollers 13 is provided for feeding the taken-out paper to the transport path L. The transported paper L is supplied to the image forming unit 8 at a predetermined timing after the sent paper is temporarily held. A registration roller 14 is provided.

  The image forming unit 8 forms an image on a sheet supplied from the manual sheet feeding unit 6 or the cassette sheet feeding unit 7, and is an image carrier disposed rotatably at a substantially central portion in the main body 2. And a charger 16, a developing device 17, a transfer roller 18 and a cleaning device 19 disposed around the photosensitive drum 15, and a laser scanner unit (LSU) 20 disposed above them. The toner container 21 according to the present invention is detachably attached to the developing device 17, and details of the toner container 21 will be described later.

  The fixing unit 9 is for fixing the toner image transferred to the sheet in the image forming unit 8 to the sheet, and includes a fixing roller 22 and a pressure roller 23 that are pressed against each other and rotated. Yes.

  Further, the paper discharge unit 10 is for discharging the paper on which the toner image is fixed in the fixing unit 9 to the outside of the main body 2, and a pair of paper discharge rollers 24 provided at the end of the conveyance path L. And a plurality of conveying guide ribs 25 in the form of longitudinal ribs for guiding the sheet conveyed through the conveying path L to the sheet discharge roller 24 and the sheet discharge tray 3 for stacking sheets discharged to the outside of the main body 2. I have.

  Next, an image forming operation of the laser beam printer 1 having the above configuration will be described.

  For example, when a print start signal is transmitted to the laser beam printer 1 from a terminal such as a personal computer (personal computer), the photosensitive drum 15 is moved in the direction of the arrow (clockwise) in FIG. And the surface thereof is uniformly charged to a predetermined potential by the charger 16. When a laser beam based on the image data transmitted from the terminal is output from the laser scanner unit 20 and irradiated onto the photosensitive drum 15, an electrostatic latent image is formed on the photosensitive drum 15. The electrostatic latent image formed on the photosensitive drum 15 is developed by the developing device 17 using toner as a developer to be visualized as a toner image. Incidentally, the toner in the developing device 17 is consumed by the development, and the toner is replenished from the toner container 21 to the developing device 17 when the remaining amount becomes a certain value or less.

  By the way, when cassette feeding is performed, the sheets stored in the sheet feeding cassette 11 of the cassette sheet feeding unit 7 are picked up one by one from the uppermost one by the pick roller 12, and fed while the direction of 180 ° is reversed. It is conveyed to the registration roller 14 by the paper roller 13.

  In the registration roller 14, the sheet is temporarily put into a standby state and then supplied to the image forming unit 8 at a predetermined timing synchronized with the toner image on the photosensitive drum 15.

  In the image forming unit 8, the sheet supplied to the transfer nip between the photosensitive drum 15 and the transfer roller 18 is conveyed while being pressed against the photosensitive drum 15 by the transfer roller 18, thereby its surface (transfer surface). ) Is transferred to the toner image on the photosensitive drum 15. The sheet onto which the toner image has been transferred is conveyed to the fixing unit 9, and is heated and pressed in the process of being sandwiched and conveyed by the fixing roller 22 and the pressure roller 23 in the fixing unit 9. Get fixed. The toner remaining on the surface of the photosensitive drum 15 (transfer residual toner) after the transfer of the toner image onto the paper is removed by the cleaning device 19.

  Thus, the sheet on which the toner image is fixed on the surface by the fixing unit 9 is conveyed upward along the conveyance path L, guided to the sheet discharge roller 24 along the conveyance guide rib 25, and is discharged by the sheet discharge roller 24. The paper is discharged and stacked on the paper discharge tray 3 at the top of the main body 2, and a series of image forming operations is completed.

When the user manually feeds the paper, the paper set on the manual tray 4 of the manual paper feeder 6 is supplied to the registration roller 14 by the manual paper feed roller 5, and thereafter the same process as described above. Then, an image is formed on the paper.
[Toner container]
Next, details of the toner container 21 according to the present invention will be described with reference to FIGS.

  2 is a sectional view of the toner container and the developing device according to the present invention, FIG. 3 is a perspective view showing the internal structure of the toner container, and FIG. 4 is a partially enlarged perspective view of FIG.

  A developing roller 27, which is a developer carrying member that is long in the vertical direction shown in FIG. 2, is rotatably disposed in an opening portion of the developing container 26 of the developing device 17 shown in FIG. 2 that faces the photosensitive drum 15. The developing container 26 contains toner, and this toner is agitated by the rotation of the two agitating members 28 and 29 that are long in the direction perpendicular to the paper surface of FIG. A toner sensor 30 for detecting the remaining amount of toner in the developing container 26 is provided on the side of the developing container 26.

  The toner container 21 is detachably mounted on the developing device 17. In the toner container 21, toner for replenishment is stored in a container container 31, and this toner is agitated by a stirring member 32 in the container container 31, and a toner replenishment port 34 is rotated by a toner conveying screw 33 that rotates. To the developing container 26 of the developing device 17 from the toner conveying screw 33.

  Here, the toner conveying screw 33 is rotationally driven by a toner replenishing motor 35 capable of forward and reverse rotation shown in FIG. 3, and a cylindrical toner shutter 36 is rotatably mounted on a part of the outer periphery thereof. As shown in FIG. 4, the toner replenishing port 34 having a rectangular hole shape is formed at a portion below the toner conveying screw 33 at the bottom of the container container 31. The toner shutter 36 opens and closes the toner replenishing port 34 in conjunction with the attaching and detaching operation of the toner container 21 to the developing device 17. When the toner container 21 is removed from the developing device 17, the toner replenishing port 34 is opened. When the toner container 21 is attached to the developing device 17 by closing and preventing the toner from leaking from the toner replenishing port 34, the toner replenishing port 34 is opened by a lever 37 (see FIG. 3) linked to the operation to develop from the toner container 21. The toner can be supplied to the device 17.

  Thus, in the present embodiment, as shown in FIG. 4, the diameter of the toner conveying screw 33 is changed into two types of large and small with the toner supply port 34 as a boundary, and the toner conveying screw 33 has a large diameter portion 33A and a small diameter. The portion 33B is formed, and the toner replenishment motor 35 is rotated forward and backward according to the toner replenishment amount. Here, the toner replenishing port 34 is disposed at a position offset to the smaller diameter side from the axial center of the conveying screw 33. Therefore, the length of the large diameter portion 33A of the toner conveying screw 33 is the length of the small diameter portion 33B. It is set longer than this.

  Incidentally, the toner replenishment amount from the toner container 21 to the developing device 17 is determined by calculating the toner consumption amount from the sheet printing rate and converting the toner consumption amount into the rotation time of the toner conveying screw 33. The determination is made for each sheet. The forward / reverse switching of the toner conveying screw 33 is performed based on the printing rate.

  Here, Table 1 shows the relationship between the printing rate (%) of one sheet and the toner supply amount (mg / sheet).

而して、本実施の形態では、印字率２０％を境としてこれよりも大きな印字率である場合には大量補給、小さいときには微量補給として区別し、大量補給時にはトナー搬送スクリュー３３を逆転させて該トナー搬送スクリュー３３の大径部３３Ａによって大量のトナーをトナー補給口３４まで図３の矢印ａ方向に搬送してトナー補給口３４から現像装置１７に補給するようにしている。

Thus, in this embodiment, when the printing rate is higher than the printing rate of 20%, it is distinguished as a large amount of replenishment, and when it is small, it is distinguished as a small amount of replenishment. A large amount of toner is conveyed to the toner replenishing port 34 in the direction of arrow a by the large diameter portion 33A of the toner conveying screw 33 and replenished to the developing device 17 from the toner replenishing port 34.

  Further, when supplying a small amount of toner, the toner conveying screw 33 is rotated forward, and a small amount of toner is conveyed to the toner replenishing port 34 in the direction of the arrow b in FIG. I have to. As described above, since a small amount of toner is conveyed by the small diameter portion 33B of the toner conveying screw 33, one operation of the toner conveying screw 33 does not become one rotation or less, and even when a small amount of toner is replenished. The toner conveying screw 33 rotates a plurality of times, so that a large variation in the replenishment amount does not occur.

  Therefore, according to the toner container 21 according to the present embodiment, a required amount of toner can be accurately replenished to the developing device 17 without a large variation even when supplying a large amount or a small amount.

  Further, in the present embodiment, the toner supply port 34 is disposed at a position offset to the small diameter portion 33B side from the center in the axial direction of the toner conveyance screw 33, so that the large diameter portion 33A of the toner conveyance screw 33 is used in FIG. The transport distance of a large amount of toner transported in the direction of arrow b is increased, and the container container 31 is prevented from being blocked by the large amount of toner.

  In the laser beam printer 1 shown in FIG. 1, the toner container 21 accurately supplies the required amount of toner to the developing device 17 without any large variation, so that a toner image with a predetermined density can be stably obtained.

  In the above description, the present invention has been described with respect to a laser beam printer and a toner container provided in the laser beam printer. However, the present invention is not limited to a printer, and may be any other image forming apparatus such as a copying machine or a facsimile machine. Of course, the present invention can be similarly applied to a toner container provided in the toner container.

1 is a side sectional view of an image forming apparatus (laser beam printer) according to the present invention. FIG. 3 is a cross-sectional view of a toner container and a developing device according to the present invention. FIG. 3 is a perspective view showing an internal structure of a toner container according to the present invention. FIG. 4 is a partially enlarged perspective view of FIG. 3.

Explanation of symbols

1 Laser beam printer (image forming device)
DESCRIPTION OF SYMBOLS 2 Printer main body 3 Paper discharge tray 4 Manual feed tray 5 Manual paper feed roller 6 Manual paper feed part 7 Cassette paper feed part 8 Image forming part 9 Fixing part 10 Paper discharge part 11 Paper feed cassette 12 Pick roller 13 Paper feed roller 14 Registration roller DESCRIPTION OF SYMBOLS 15 Photosensitive drum 16 Charger 17 Developing device 18 Transfer roller 19 Cleaning device 20 Laser scanner unit (LSU)
DESCRIPTION OF SYMBOLS 21 Toner container 22 Fixing roller 23 Pressure roller 24 Paper discharge roller 25 Conveying guide rib 26 Developing container 27 Developing roller 28, 29 Stirring member 30 Toner sensor 31 Container container 32 Stirring member 33 Toner conveying screw 33A Large diameter part 33B of toner conveying screw Small diameter portion of toner conveying screw 34 Toner replenishing port 35 Toner replenishing motor 36 Toner shutter 37 Lever L Conveying path

Claims (4)

In a toner container that contains toner therein and conveys toner to a toner replenishing port by a toner conveying screw that is rotationally driven by a toner replenishing motor.
A toner container, wherein the diameter of the toner conveying screw is changed with the toner supply port as a boundary, and the toner supply motor is rotated in the forward and reverse directions according to the toner supply amount.   2. The toner container according to claim 1, wherein the forward / reverse switching of the toner conveying screw is performed based on a printing rate.   3. The toner container according to claim 1, wherein the toner replenishing port is disposed at a position offset to a smaller diameter side than an axial center of the conveying screw.   An image forming apparatus comprising the toner container according to claim 1.

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