JP2006301164A - Developing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of developer by smoothly transporting the developer in a transfer area in a developing apparatus circulating and transporting developer in an apparatus by two pieces of transporting means. <P>SOLUTION: The rotating direction in a bottom most end of screws 1 and 2 in both end parts of the screws 1 and 2 which are transfer areas for the developer is made to be the same direction as the transporting direction of the developer in a developing apparatus. Here, the screws 1 and 2 are preferably provided with shaft parts 11 and 21 in which two shaft members 11a, 11b or two shaft members 21a, 21b are connected to be able to be rotated in reverse directions to each other by connecting means 12 or 22. Furthermore, from the view point of improving the transportability of the developer, the screws 1 and 2 are preferably provided with spiral blades 13 and 23 formed on the shaft members 11 and 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device, and more particularly to a developing device that includes two conveying means and circulates and conveys developer in the apparatus.

  In a developing device using a so-called two-component developer composed of a toner and a carrier, if the developer is not sufficiently mixed or non-uniformly mixed, uneven toner density or uneven charge amount occurs. As a result, image density unevenness occurs and a good image cannot be obtained. For this reason, a developing device as shown in FIGS. 5 and 6 has been proposed in order to sufficiently mix and stir the developer. FIG. 5 is a vertical sectional view of the developing device, and FIG. 6 is a plan view. The developing device includes a rotatable developing sleeve 3 incorporating a plurality of magnetic poles, a regulating blade 6 that regulates the amount of developer on the developing sleeve 3 conveyed to the developing unit, and a parallel arrangement in the horizontal direction. It is formed between two screws (conveying means) 1 ′, 2 ′ for agitating and conveying the developer in the opposite direction and the two screws 1 ′, 2 ′. The other screw is provided with a partition plate 4 that allows the developer to move and prevents the developer from moving at both ends.

  The two screws 1 ′ and 2 ′ have spiral blades 13 ′ and 23 ′ formed on the shaft portions 11 ′ and 21 ′ with the same inclination angle, and are driven in the same direction by a drive mechanism (not shown). Rotates and conveys developer in opposite directions. Then, the developer moves from one screw to the other screw at both ends of the screws 1 ′ and 2 ′. As a result, the developer composed of the toner and the magnetic carrier is always circulated and stirred in the apparatus.

On the other hand, the developing sleeve 3 includes a developing magnetic pole N ₁ , a transporting magnetic pole S ₁ , a peeling magnetic pole N ₂ , a pumping magnetic pole N ₃ , and a blade magnetic pole S ₂ in this order inside a metal cylindrical sleeve having a surface with a few μm unevenness. It has a fixed magnet with five magnetic poles. When the developing sleeve 3 rotates in the direction of the arrow, the developer is pumped from the screw 1 ′ to the developing sleeve 3 by the magnetic force of the pumping magnetic pole N ₃ . The developer carried on the surface of the developing sleeve 3 is regulated by the regulating blade 6 and then conveyed to the developing unit. In the developing section, a bias voltage (not shown) is applied to the developing sleeve 3, and the generated developing electric field moves the charged toner to the electrostatic latent image on the photosensitive drum (latent image carrier) 5 for development. . Thereafter, the developer on the developing sleeve 3 is conveyed to the inside of the apparatus by the conveying magnetic pole S ₁ , separated from the developing sleeve 3 by the peeling electrode N ₂ , and circulated and conveyed again inside the apparatus by the screws 1 ′ and 2 ′. It is mixed and stirred with a developer that has not been used. The developer is newly supplied from the screw 1 ′ to the developing sleeve 3 by the pumping pole N ₃ .

The amount of developer in the developing device is usually set such that the shaft portions 11 ′ and 21 ′ of the screws 1 ′ and 2 ′ are hidden by the developer. If the amount of the developer is larger than this, circulation of the developer will be slowed and stirring will be insufficient, and toner density unevenness, charge amount unevenness, and insufficient charging may occur. This is because the amount of developer pumped up by the magnetic pole N ₃ may be insufficient.
Japanese Patent Laying-Open No. 2003-107859 (Claims, FIGS. 2 and 3)

  Such a conventional apparatus in which the two screws 1 'and 2' are arranged in parallel to circulate the developer in the apparatus has the following problems. That is, when the two screws 1 ′ and 2 ′ are rotated in the same direction, in the region where the developer moves from the screw 2 ′ to the screw 1 ′, the rotation direction and development at the lowermost end of the screws 1 ′ and 2 ′ are developed. The moving direction of the developer becomes the same (see FIG. 7A), and the developer moves smoothly. However, in the region where the developer moves from the screw 1 ′ to the screw 2 ′, the screws 1 ′ and 2 ′ The rotation direction at the lowermost end and the moving direction of the developer are reversed (see FIG. 5B), and the developer is not smoothly moved, and the developer is stressed and deteriorated.

  When the two screws 1 ′ and 2 ′ are rotated in opposite directions, the rotation directions at the lowest ends of the two screws are opposite at both ends of the screws 1 ′ and 2 ′. A similar problem occurs in that the developer is not smoothly moved at both ends of the screw.

  If the developer does not move smoothly in the transfer area in this way, the circulation time in the developer agitation becomes longer, or the developer is biased in the axial direction of the screw, resulting in toner replenishment. As a result, there is a problem in that the diffusion of the toner is delayed and the toner density and the charge amount in the axial direction become non-uniform.

  If the toner density and charge amount in the axial direction of the screw are non-uniform, the image density of the resulting image will be non-uniform, or if the toner is not sufficiently charged, fogging will occur on the image or toner scattering will occur. May occur.

  The present invention has been made in view of such a conventional problem, and the object of the present invention is to smoothly move the developer in the transfer region without deteriorating the developer. It is another object of the present invention to provide a developing device capable of obtaining a good image without causing uneven image density, fogging, and toner scattering.

  According to the present invention, the developer carrying member that carries the developer and transports it to the developing unit facing the image carrier, and the shaft portion are arranged in parallel in the horizontal direction, and the developer is placed in the axial direction and in the opposite direction. Formed between the first conveying means and the second conveying means, and the first conveying means and the second conveying means, and the developer from one conveying means to the other conveying means at both ends of both conveying means. And a partition plate that prevents the developer from moving at other than both ends, and the rotation direction at the lowermost ends of both conveying means at both ends is the same as the developer conveying direction. A developing device characterized by the above is provided.

  Here, it is preferable that the shaft portions of the first transport unit and the second transport unit are formed by connecting two shaft members so as to be rotatable in opposite directions by the connecting unit.

  Further, from the viewpoint of improving developer transportability, it is preferable to use a screw in which spiral blades are formed on a shaft member as the first transport means and the second transport means.

  In the developing device of the present invention, in the developer delivery areas at both ends of the transport means, the rotation direction at the lowermost ends of both transport means is the same as the developer transport direction. Move smoothly. As a result, the developer is not deteriorated, image density unevenness, fogging, and toner scattering can be prevented, and a good image can be obtained.

  As the shaft portions of the first transport means and the second transport means, when two shaft members are connected so as to be rotatable in opposite directions by the connecting means, the shaft portions are arranged at both end portions without increasing the size of the apparatus. Can be rotated in the opposite direction.

  Further, when a screw in which a spiral blade is formed on a shaft member is used as the first transport unit and the second transport unit, the transportability of the developer can be further improved.

  Hereinafter, the developing device according to the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments.

  FIG. 1 is a schematic plan view showing an example of a developing device according to the present invention. The developing device includes a box-shaped housing 7 including a pair of side walls 71a and 71b arranged at an interval in the axial direction, and includes a developing sleeve (developer carrier) 3 and a screw (first conveying means). 1) The screw (second conveying means) 2 is supported between the pair of side walls 71a and 71b so as to be rotatable and parallel to each other. In addition, the shaft portion 11 of the screw 1 and the shaft portion 21 of the screw 2 are It is arranged horizontally. Between the screw 1 and the screw 2, a partition plate 4 that prevents the developer from moving is formed in the axial direction except for both end portions. Regions where the developer can be transferred between the screw 1 and the screw 2 are formed at both end portions where the partition plate 4 is not formed.

  The screws 1 and 2 are formed by coaxially connecting two shaft members 11a and 11b and shaft members 21a and 21b by connecting means 12 and 22, respectively, so that the shaft members 11a and 11b, On the members 21a and 21b, spiral blades are formed in directions opposite to each other. An example of the connecting means 12 and 22 is shown in FIG. In FIG. 2, an example of the connecting means will be described taking the shaft portion 11 as an example, but the same connecting means can also be used for the shaft portion 21. In FIG. 6A, a flange portion 111 is formed in the vicinity of the end portion of the shaft member 11b, and the bearing 14 is externally fitted to a protruding portion 112 that protrudes outward in the axial direction from the flange portion 111. On the other hand, an enlarged cylindrical portion 113 is formed at the end of the shaft member 11 a, and the cylindrical portion 113 is fitted on the bearing 14. Thereby, shaft member 11a, 11b can be rotated independently. In FIG. 5B, the cylindrical portion 113 of the shaft member 11a is externally fitted to the protruding portion 112 of the shaft member 11b without the bearing 14 interposed. In the case of this structure, the outer periphery of the protruding portion 112 and the inner periphery of the cylindrical portion 113 slide directly, so that at least one surface of the protruding portion 112 and the cylindrical portion 113 is covered with a fluorine-based resin or the like. It is desirable to keep it.

  As seen from the right side direction (D direction) in FIG. 1, the shaft member 11a of the screw 1 rotates clockwise and the shaft member 11b rotates counterclockwise, while the spiral member formed on the shaft members 11a and 11b. The blades 23a and 23b are formed in opposite directions. For this reason, even if the shaft members 11a and 11b rotate in directions opposite to each other, the developer is conveyed in the same direction (the direction from the left to the right in the drawing). Similarly, in the case of the screw 2, the shaft member 21a rotates clockwise and the shaft member 21b rotates counterclockwise, while the spiral blades formed on the shaft members 21a and 21b are in opposite directions. Is formed. For this reason, even if the shaft members 21a and 21b rotate in directions opposite to each other, the developer is conveyed in the same direction (direction from right to left in the drawing). Accordingly, the developer is circulated and conveyed in the developing device by the screws 1 and 2 as in the conventional case.

  AA line sectional view and BB line sectional view of FIG. 1 are shown in FIG. As is clear from FIG. 5A, in the region where the developer is transferred from the screw 2 to the screw 1, the rotation direction at the lowest end of the screws 1 and 2 is the same as the moving direction of the developer. Further, as understood from FIG. 6B, in the region where the developer is transferred from the screw 1 to the screw 2, the rotation direction at the lowest end of the screws 1 and 2 is the same as the moving direction of the developer. . As a result, the developer moves more smoothly in the delivery area than in the past, and the deterioration of the developer is remarkably suppressed. In the developing device of FIG. 1, the developer is circulated counterclockwise, but may of course be circulated clockwise. However, in this case, it is necessary to reverse the rotational directions of the screws 1 and 2 and the directions of the blades 13 and 23 as described above. The direction in which the developer is circulated is preferably determined by the position of a supply port (not shown) when toner is supplied to the developer. In other words, the circulation direction may be such that the conveyance path from the supply port to the developing sleeve 3 becomes longer. This is because the newly supplied toner is sufficiently agitated and mixed with the existing developer before the developer is supplied to the developing sleeve 3.

An example of a drive mechanism that rotates the shaft members 11a and 11b and the shaft members 21a and 21b in opposite directions is shown in FIG. 1A is a view of the developing device of FIG. 1 viewed from the left side (C direction in FIG. 1), and FIG. 1B is a view of the developing device of FIG. 1 viewed from the right side (D direction of FIG. 1). It is. As described above, the shaft members 11a and 11b and the shaft members 21a and 21b can be rotated in the opposite directions by the connecting means. Therefore, the shaft members are driven to rotate in opposite directions from both side surfaces of the developing device. give. That is, as shown in FIG. 5A, a drive gear G ₁₁ to which drive is transmitted from a motor (not shown) is attached to the outside of the side wall 71a of the housing 7, and the developing sleeve 3 is attached to the drive gear G _11. gear G ₁₂ attached to the end portion of one side of the rotary shaft 31 is engaged teeth. Thereby, the rotation drive is transmitted to the developing sleeve 3. Also the drive gear G ₁₁ is a gear G ₁₃ is meshed in the gear G _13, the gear G ₁₄ which is attached to one end of the shaft member 11a is meshed. And the gear G _14, the gear G ₁₅ is meshed gear G ₁₆ which is attached to one end of the shaft member 21a to the gear G ₁₅ is meshed. The configuration of such a gear, the driving gear G ₁₁ is rotated counterclockwise, the gear G ₁₂ is rotated clockwise, the gear G ₁₄ and the gear G ₁₆ rotates clockwise. Thus, the developing sleeve and the shaft member 11a, a gear G ₁₂ respectively to the shaft member 21a, the gear G _14, rotates in the same direction as the gear G _16.

On the other hand, as shown in FIG. 4 (b), on the outside of the side wall 71b of the housing 7, the gear G ₂₁ and the gear G ₂₂ which is attached to the other end of the developing sleeve 3 is meshed, in the gear G ₂₂ , gear G ₂₃ which is attached to one end of the shaft member 11b is meshed. The gear G ₂₄ meshes with the gear G ₂₃ , and the gear G ₂₅ attached to one end of the shaft member 21 b meshes with the gear G ₂₄ . As described above, the gear G ₁₂ is rotated by the rotation of the driving gear G ₁₁ which is attached to the side wall 71a of the housing 7, when the developing sleeve 3 rotates, the gear G ₂₁ is attached to the other end of the developing sleeve 3 In FIG. 4B, it rotates counterclockwise. Accordingly, the gear G ₂₃ and the gear G ₂₅ is rotated counterclockwise, the shaft member 11b and the shaft member 21b is rotated counterclockwise.

  The rotational drive mechanism shown in FIG. 4 is a mechanism that drives the developing sleeve and the shaft members 11a, 11b, 21a, and 21b by one drive source, but is not limited to this, and a plurality of drives Of course, the developing sleeve and the shaft members 11a, 11b, 21a, and 21b may be driven by the source.

  In the embodiment described above, the screw is used as the conveying means. However, the present invention is not limited to this, and a conventionally known one having a paddle or a blade attached to the shaft portion may be used. However, a screw is preferable from the viewpoint of developer transportability and mixing properties. What is necessary is just to determine suitably the pitch and outer diameter of a screw from the magnitude | size of a developing device, a developer amount, etc. FIG.

1 is a schematic horizontal sectional view showing an example of a developing device according to the present invention. It is a schematic diagram which shows an example of a connection means. It is the sectional view on the AA line of FIG. 1, and the BB sectional drawing. It is a left-right side view of the housing for showing a drive mechanism. It is a schematic diagram of a conventional developing device. FIG. 6 is a plan view of the conventional developing device of FIG. 5. FIG. 10 is a vertical sectional view of a developer delivery area in a conventional developing device.

Explanation of symbols

1 screw (first transport means)
2 Screw (second transport means)
3 Development sleeve (developer carrier)
4 Partition plate 5 Photosensitive drum (image carrier)
6 Restricting blades 11, 21 Shafts 11a, 11b Shaft members 12, 22 Connecting means 13a, 13b Blades 21a, 21b Shaft members 23a, 23b Blades

Claims (3)

A first carrier that carries a developer and conveys the developer to a developing unit facing the image carrier and a shaft portion arranged in parallel in the horizontal direction and conveys the developer in the axial direction and in the opposite direction. Formed between the first conveying means and the second conveying means, and enables the developer to move from one conveying means to the other conveying means at both ends of both conveying means, In the developing device provided with a partition plate that prevents the movement of the developer other than both ends,
A developing device characterized in that the rotation direction at the lowest end of both conveying means at both ends is the same as the conveying direction of the developer.   2. The developing device according to claim 1, wherein the shaft portions of the first transport unit and the second transport unit are formed by connecting two shaft members so as to be rotatable in opposite directions by a connecting unit.   The developing device according to claim 1 or 2, wherein the first conveying means and the second conveying means are screws each having a spiral blade formed on a shaft member.

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