JP2007094160A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of sufficiently mixing a developer and a toner. <P>SOLUTION: A spiral blade 32 for supplying the toner is a single spiral blade. Also, a spiral blade 31 for stirring and conveyance is a double spiral blade in which double spiral is extended to a rotary shaft 30. The spiral blade 32 for supplying the toner is continuously connected to one 31A of the spiral blades 31 for stirring and conveyance which are the double spiral blades. Since the spiral blade 32 for supplying the toner is the single spiral, the toner is reasonably mixed with the developer and since the spiral blade 32 for supplying the toner is connected to the spiral blades 31 for stirring and conveyance, the toner mixed with the developer is smoothly transferred to a developer conveyance path. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and more particularly to a developing device using a two-component developer containing toner and a carrier.

  One developer for developing an electrostatic image is a two-component developer. The two-component developer contains a toner and a carrier, which are used while being stirred in a developing container. A stirring and conveying spiral shaft is provided in the developing container to agitate the developer and convey it in a predetermined direction. When the toner is supplied from the toner replenishing port according to the toner consumption, the toner and the developer (toner and carrier) are stirred and mixed.

By the way, when toner is supplied from above the developer, the toner accumulates on the developer, and there is a problem that mixing of the developer and the toner cannot be sufficiently performed. If mixing of the developer and the toner cannot be sufficiently performed, there is a possibility that uneven density of the image due to insufficient mixing of the developer toner and the carrier, or background staining of the image due to insufficient charging of the toner may occur.
Therefore, conventionally, a toner supply spiral shaft for supplying toner supplied into the developing container is provided on the same axis as the stirring and conveying spiral shaft, and the stirring and conveying spiral disposed on the stirring and conveying path is provided. A device that supplies toner from the axial direction is known (Patent Document 1).
JP 2002-148915 A (FIGS. 6 and 7)

However, in such a configuration, the toner stays in the vicinity of the boundary between the toner supply spiral shaft and the stirring and transporting spiral shaft without being mixed with the developer. For this reason, the developer and the toner are sufficiently mixed. In some cases it was not done.
Accordingly, an object of the present invention is to provide a developing device capable of sufficiently mixing a developer and a toner.

  In order to achieve the above object, the invention according to claim 1 extends in the longitudinal direction in which a developer containing at least a carrier and a toner is accommodated, and is a developer transport path (21, 9, 10, 19, 20), a toner replenishing port (18) formed on one end (7 b) side of the developing container and supplying toner into the developing container, and the above A rotating shaft (30) extending in the longitudinal direction of the developing container, and a spiral blade (31) for stirring and transporting the developer while stirring the developer, and extending in a double spiral shape along the rotating shaft; The toner is disposed on the toner replenishing port side so as to be adjacent to the agitating / conveying spiral blade, and is projected in a single spiral shape along the rotating shaft, and the toner replenished from the toner replenishing port Transport route A spiral shaft (11) having a toner supply spiral blade (32) for conveying the toner continuously to one of the double spiral spiral stirring blades. It is a developing device characterized by being connected to.

In addition, the alphanumeric characters in parentheses represent corresponding components in the embodiments described later.
According to the first aspect of the present invention, the toner supply spiral blade for transporting the replenished toner to the developer transport path side of the spiral shaft is a single spiral. In addition, the toner supply spiral blade is connected to one of the double spiral agitating and conveying spiral blades, so that the toner biting into the developer can be smoothly fed into the developer conveyance path. Can be moved to. The toner transported to the developer transport path is stirred with the developer by the stirring transport spiral blade. Thereby, the toner and the developer are agitated, and the toner and the developer can be sufficiently mixed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a main part of an image forming apparatus to which a developing device according to an embodiment of the present invention is applied. Referring to FIG. 1, an image forming apparatus 1 includes a cylindrical photosensitive drum 2 that forms an electrostatic latent image. After the surface of the photosensitive drum 2 is uniformly charged by the main charger 3, it is exposed based on the image data, and an electrostatic latent image is formed on the photosensitive drum 2. The electrostatic latent image formed on the photosensitive drum 2 becomes a toner image that is made visible by the developing device 4 using a two-component developer containing a magnetic carrier and toner, and is recorded on a sheet by the transfer unit 5. Reference numeral 6 denotes a cleaner for cleaning the surface of the photosensitive drum 2 after the toner image is transferred.

  The developing device 4 develops the electrostatic latent image formed on the photosensitive drum that is an image carrier. The developing device 4 includes a developing container 7 in which a two-component developer is accommodated. The developing container 7 is formed with a partition wall 8 that rises upward from its bottom surface. The partition wall 8 partitions the developing container 7 from the first chamber 9 and the second chamber 10. A first spiral shaft 11 is rotatably disposed in the first chamber 9, and a second spiral shaft 12 is rotatably disposed in the second chamber 10.

In the developing container 7, a magnet roller 14 that is a toner replenishing roller is disposed above the spiral shaft 12, and a developing roller 15 is disposed facing the magnet roller 14. The developing roller 15 is disposed so as to face the photosensitive drum 2.
In the developing container 7, the developer is circulated in the developing container 7 by the first spiral shaft 11 and the second spiral shaft 12, and the toner is charged. The developer is sucked and conveyed to the magnet roller 13, and the toner is supplied to the developing roller 15 due to a potential difference between the magnet roller 14 and the developing roller 15. A toner layer is formed on the developing roller 15, and the electrostatic latent image is developed on the photosensitive drum 2 by the toner layer on the developing roller 15.

FIG. 2 is a view of the first spiral shaft 11 and the second spiral shaft 12 in the developing device as viewed from above.
Referring to FIG. 2, each of first chamber 9 and second chamber 10 is an elongated chamber extending in the longitudinal direction. The partition wall 8 is cut out at both longitudinal ends 8 a and 8 b of the developing container 7, and the first chamber 9 and the second chamber 10 are connected by passage ports 19 and 20. A first spiral shaft 11 is disposed in the first chamber 9, and a second spiral shaft 12 is disposed in the second chamber 10.

The spiral shafts 11 and 12 extend in the longitudinal direction of the developing container 7 and are parallel to each other. An end face on one end side (the right side shown in FIG. 2) of the first chamber 9 extends deeper than the second chamber 10. The toner is replenished from above through the toner replenishing port 18 into the extended region 22 that extends to the back.
The first spiral shaft 11 and the second spiral shaft 12 rotate in different directions (see FIG. 1). When a driving force is applied to gears (not shown) interlocked with the spiral shafts 11 and 12, the developer stored in the developer container 7 is stirred by the first spiral shaft 11 while being agitated. The chamber 9 is moved in the direction of the arrow (1) shown in FIG. Then, when the developer reaches the vicinity of one end 7a (right side shown in FIG. 2) of the developing container 7, the developer moves toward the second chamber 10 through the passage port 19 (arrow (2)). In the second chamber 10, the developer moves in the second chamber 10 in the direction of the arrow (3) shown in FIG. At this time, the developer in the second chamber 10 is pulled up by the attracting force of the magnet roller 14 (see FIG. 1) located adjacent to the second spiral shaft 12, whereby a developing layer is formed on the surface of the magnet roller 14. It is formed. The developer that has reached the vicinity of the other end 7b (left side shown in FIG. 2) of the developing container 7 flows again into the first chamber 9 through the passage port 20 (arrow (4)). In the first chamber 9, the toner replenished from the toner replenishing port 18 in the extended region 22 moves in the direction of the arrow (5) by the first spiral shaft 11, and the developer that has flowed into the first chamber 9 , The toner is mixed. Then, the toner is mixed with the toner that has flowed into the first chamber 9 again, and is conveyed while being agitated by the first spiral shaft 11 in the first chamber 9 (arrow (2)). In the developer container 7, a developer transport path 21 that is a circulation path is formed by the paths indicated by arrows (1) to (4), that is, the first chamber 9, the second chamber 10, and the passage ports 19 and 20. Yes.

FIG. 3 is an enlarged view of the left end portion shown in FIG.
Referring to FIGS. 2 and 3, the first spiral shaft 11 includes a rotating shaft 30 that extends in the longitudinal direction of the developing container 7, a stirring and conveying spiral blade 31, and a toner supplying spiral blade 32.
From the toner supply port 18 to the developer conveyance path 21, a toner supply region 23 in which the toner replenished from the toner supply port 18 is conveyed is formed. A toner supply spiral blade 32 is disposed in a position corresponding to the toner supply region 23 in the first spiral blade 30. The toner supply spiral blade 32 conveys the toner replenished from the toner replenishing port 18 toward the developer transport path 21. The toner supply spiral blade 32 is a single spiral blade and has a pitch of 30 mm.

In this embodiment, the toner supply spiral blade 32 is disposed in the entire area corresponding to the toner supply region 23 in the first spiral blade 30. However, the toner supply spiral blade 32 is disposed in the toner supply port 18. As long as it covers the extended region 22 where the is arranged, the arrangement range may be a little narrower.
Further, in the first spiral blade 30, on the developer transport path 21 side as viewed from the toner supply spiral blade 32, a stirring transport spiral is provided at a position excluding one end portion 7 a (right side shown in FIG. 2). A blade 31 is arranged. The stirring / conveying spiral blade 31 is a double spiral blade in which a double spiral protrudes from the rotating shaft 30. The pitch of the stirring and conveying spiral blades 31 is 30 mm. The stirring and conveying spiral blade 31 has the same pitch as that of the toner supplying spiral blade 32, but is a double spiral blade, and therefore has a higher conveying force and stirring force than the toner supplying spiral blade 32.

  The toner supply spiral blade 32 is continuously connected to one end 31A of the stirring and conveying spiral blade 31 which is a double spiral blade. This is a feature of this embodiment. Of the stirring and conveying spiral blades 31, the spiral blade 31 </ b> A connected to the toner supplying spiral blade 32 mainly has a role of conveying the developer. On the other hand, the spiral blade 31B not connected to the single spiral blade mainly has a role of stirring the toner and the carrier.

On the other hand, the second spiral shaft 12 conveys the developer while stirring. The second spiral shaft 12 includes a rotation shaft 34 extending in the longitudinal direction of the developing container 7 and a spiral blade 35. The spiral blade 35 is a double spiral blade in order to maintain the same conveying force as that of the stirring and conveying spiral blade 31.
In this embodiment, since the toner supply spiral blade 32 is a single spiral, the toner can be forced into the developer without difficulty, and the toner supply spiral blade 32 is a double spiral. Since it is connected to one of the blades 31, the toner biting into the developer can be smoothly moved to the developer transport path 21.

Further, since the pitch of the toner supply spiral blades 32 is the same as the pitch of the stirring and conveying spiral blades 31, the toner can be smoothly conveyed.
The present invention is not limited to the above-described embodiment.
In the above description, the pitch of the toner supply spiral blades 32 is the same as the pitch of the stirring and conveying spiral blades 31, but may be different from the pitch of the stirring and conveying spiral blades 31.

Further, although the developer transport path 21 formed in the developing container 7 is a circulation path, the developer transport path 21 may be transported in one direction instead of being circulated.
In addition, various design changes can be made within the scope of matters described in the claims.

1 is a diagram illustrating a schematic configuration of a main part of an image forming apparatus to which a developing device according to an embodiment of the present invention is applied. It is the figure which looked at the 1st spiral axis and the 2nd spiral axis in a developing device from the upper part. It is the figure which expanded the left side edge part shown in FIG.

Explanation of symbols

4 Developing Device 7 Developing Container 9 First Chamber (Developer Transport Path)
10 Second chamber (Developer transport path)
11 First spiral axis (spiral axis)
18 Toner replenishing port 21 Developer transport path 30 Rotating shaft 31 Spiral blade 32 for agitation transport 32 Spiral blade for toner supply

Claims (1)

A developing container having a developer conveying path in which a developer containing at least a carrier and a toner is accommodated and extending in a longitudinal direction;
A toner replenishing port formed on one end side of the developing container and supplying toner into the developing container;
A rotating shaft extending in the longitudinal direction of the developing container, a spiral blade for stirring and transporting the developer while stirring the developer, and a spiral for stirring and transporting the developer while stirring the developer. The toner is disposed on the toner supply port side so as to be adjacent to the blade, and is projected in a single spiral shape along the rotation axis, and the toner supplied from the toner supply port is moved to the developer transport path side. A spiral shaft having a toner supply spiral blade for conveyance;
2. A developing apparatus according to claim 1, wherein the toner supply spiral blade is continuously connected to one of the double spiral spiral blades for stirring and conveying.

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