JP2007233083A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device etc., which is increased in conveying/agitating efficiency of toner by preventing toner from sticking on a blade without deteriorating the toner. <P>SOLUTION: The developing device is equipped with a housing 102 holding toner, a rotating shaft 107 arranged in the housing 102 and conveyance screws 104 and 105 which are arranged on the rotating shaft and convey the toner by the rotation of the rotating shaft, and a development roller in contact with the outside of the housing 102 and the inside of the housing 102 to acquire the toner from the conveyance screws 104 and 105. The blade 106 is made of an elastic member and the housing 102 has projections, which contacts and leaves the blade to deform the blade according to the rotation of the rotating shaft, on its internal surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device used for developing an image forming apparatus such as a copying machine, a multifunction peripheral, and a printer, and an image forming apparatus including the developing device.

  As shown in FIG. 4, the developing device 400 used when the latent image formed on the photoconductive drum of the image forming apparatus is made visible is provided at a position close to the photoconductive drum 401. . The developing device 400 includes a housing 402 that holds toner, a developing roller 403 supported by the housing 402, and conveying screws 404 and 405. The rotating shafts 407 of the conveying screws 404 and 405 are provided with blades 406 having a uniform diameter formed in a spiral shape in order to stir and circulate the toner in the housing 402.

  As shown in FIG. 5, the developing roller 403 is configured with a magnet roller 408, and the outer periphery of the magnet roller 408 is configured with a developing sleeve 409. The magnet roller 408 has a five-pole structure. The magnet roller 408 is fixed, and the developing sleeve 409 is rotatable. As the developing sleeve 409 rotates, the toner in the housing 402 stirred and circulated by the conveying screws 404 and 405 is conveyed to the outside of the housing 402 by the developing roller 403.

  Above the developing roller 403, a regulating member (magnetic blade) 410 that regulates the amount of toner conveyed by the developing roller 403 is provided. The toner conveyed to the outside by the developing roller 403 is given a constant charge by the regulating member 410 and regulated to a certain amount and is supplied to the photosensitive drum 401.

  The surface of the photosensitive drum 401 is uniformly charged, and then a latent image is formed by a laser. As a result, the charged state at the position where the latent image is formed is a state where the charged toner supplied from the developing roller 403 adheres. Therefore, the toner supplied from the developing roller 403 adheres only to the position where the latent image is formed.

  Of the toner supplied to the photosensitive drum 401, the toner that has not adhered to the photosensitive drum 401 is collected in the housing 402 through the developing roller 403. When the toner that could not adhere to the photosensitive drum 401 is collected in the housing 402, the charged toner is present in the housing 402. When the toner collected in this manner is supplied again to the photosensitive drum 401 by the developing roller 403, the charge is again charged by the regulating member 410 when being supplied to the photosensitive drum 401 despite being charged. Is given. For this reason, when the charge is applied again, the toner is excessively charged, so that a development failure such as a decrease in image density occurs.

  Further, the collected toner is not uniformly present in the housing 402 but is present in a part of the housing 402, and the replenishment toner does not sufficiently mix and disperse the toner in the developing device. Even if the toner is supplied to the photosensitive drum 401, the above-described development failure occurs.

  In order to prevent this, in the developing device 400, the conveying screws 404 and 405 stir the toner, and newly added uncharged toner and charged toner are uniformly dispersed in the housing 402. By doing so, the above-mentioned development failure is prevented.

  However, particularly charged toner tends to accumulate, and adheres not only to the corner in the housing but also to the blades of the conveying screws 404 and 405. Due to the adhesion, the toner conveying / stirring ability by the conveying screw is lowered, and toner conveyance failure occurs due to toner overcharging and fluidity deterioration. As a result, a part of the toner is excessively charged, resulting in the development failure.

On the other hand, Japanese Patent Application Laid-Open No. 2001-42733 discloses a technique for scraping off toner adhering to a blade by bringing an elastic scraping plate into contact with a conveying screw.
JP 2001-42733 A

  However, the scraping plate disclosed in Patent Document 1 cannot sufficiently contact the blades. That is, there is a gap between the plates, that is, there is a portion where the toner cannot be scraped off.

  Further, the operation of scraping off the toner causes the external additive (abrasive etc.) to be peeled off from the toner particle surface by the stress, or the external additive is embedded in the toner particle surface, that is, deteriorates the toner. . The deterioration of the toner results in development failure.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device that improves toner conveyance / stirring efficiency by preventing toner from adhering to a blade without deteriorating the toner.

  The developing device according to the present invention includes a housing in which toner is held, a conveyance screw including a rotation shaft disposed in the housing, a blade disposed on the rotation shaft and conveying the toner by rotation of the rotation shaft, and a housing And a rotatable developing roller that contacts the inside of the housing and the inside of the housing and acquires toner from the conveying screw. The blade is constituted by an elastic member, and the housing is characterized in that an inner surface is provided with a protrusion that contacts and separates the blade in a deformable manner according to the rotation of the rotation shaft.

  According to this developing device, since the protruding portion contacts and separates from the blade, it affects the periphery of the contact portion of the blade made of an elastic body. Therefore, the blade does not contact the protruding portion at all positions of the blade. It is possible to remove the adhered toner for the whole. Further, the removal by deformation or elasticity does not deteriorate the toner, that is, the influence of the toner deterioration on the image can be suppressed.

  Note that the protrusion is configured to be provided at a toner-free position that does not hinder toner conveyance, so that the protrusion does not hinder toner conveyance.

  An image forming apparatus including the developing device is also provided.

  According to the present invention, in the developing unit, since the protrusion comes into contact with or separates from the blade and affects the vicinity of the contact portion of the blade made of an elastic body, the protrusion is brought into contact with all positions of the blade. Therefore, it is possible to remove the adhered toner from the entire blade. Further, the removal by deformation or elasticity does not deteriorate the toner, that is, the influence of the toner deterioration on the image can be suppressed.

  Further, the protrusion is provided at a toner-free position that does not hinder toner conveyance, so that the protrusion does not hinder toner conveyance.

  FIG. 1 is an internal configuration diagram of a copier 10 incorporating a developing device 100 according to the present embodiment. As shown in FIG. 1, the copying machine 10 includes a main body 90 and a scanner unit 91 that reads a document provided on the upper side of the main body.

  A photosensitive drum 101 is provided inside the main body 90. Around the photosensitive drum 101, a charger 11, a laser 12, a developing device 100, a transfer device 13, and a static eliminator 14 are provided.

  As shown in FIGS. 2 and 3, the developing device 100 includes a housing 102, conveying screws 104 and 105 provided inside the housing 102, and a developing roller 103 having surfaces on the inside and outside of the housing 102, Further, as shown in FIG. 3, a charger 110 is provided.

  The housing 102 is provided with a toner replenishing port 108 at a position located above during the printing operation of the developing device 100 or the toner replenishing operation. Further, a sensor 109 that detects a decrease in toner is provided in the vicinity of the toner supply port 108. The sensor controls toner supply from the toner supply port 108 by detecting magnetism and pressure. In addition, a plurality of protrusions 111 and 112 arranged in the housing 102 so as to come into contact with the blades of the conveying screws 104 and 105 are provided, for example, at equal intervals in the longitudinal direction of the conveying screw.

  In order to stir and circulate (convey) the toner in the housing 102, the conveying screws 104 and 105 are provided with a spirally formed blade 106 along the rotating shaft 107 from the vicinity of the end to the vicinity of the other end. Yes. In addition, the said blade | wing 106 is comprised with the elastic member. Further, a plurality of conveying screws 104 and 105 are arranged on one side of the developing roller 103, and a central portion in the longitudinal direction of the conveying screw is separated by a central wall 110 so that toner does not come and go.

  As shown in FIG. 3, the developing roller 103 is composed of a magnet roller 108 as in the prior art, and the outer periphery of the magnet roller 108 is composed of a developing sleeve 109 that can rotate in the direction of arrow X. As shown in FIG. 2, the magnet roller 108 has a five-pole structure. The magnet roller 108 is fixed, and the developing sleeve 109 is rotatable.

  The charger 110 is attached to the inner side of the housing 102 and above the developing roller 103, and applies a charge to the toner conveyed to the outside of the housing 102 through the upper surface of the developing roller 103.

The main body 90 includes paper feeding cassettes 21 and 22 for storing paper used for copying at the lower part. Above the paper feed cassettes 21 and 22, paper feed rollers 23 and 24 for taking out the sheets stored in the paper feed cassette one by one from the paper feed cassette and feeding them to the conveyance path 20 are provided.
In the middle of the conveyance path 20, a conveyance roller 25 that conveys the fed sheet downstream is provided. The sheet is conveyed between the photosensitive drum 101 and the transfer unit 13 by the conveying roller 25, and the toner image formed on the photosensitive drum 101 is transferred when passing between the sheets. The sheet that has passed through the photosensitive drum 100 and the transfer unit 13 is conveyed between the fixing roller 27 and the pressure roller 28 by the conveying belt 26 or the like. The sheet conveyed between the fixing roller 27 and the pressure roller 28 is fixed on the toner image transferred by the fixing roller 27 and the pressure roller 28. The sheet on which the toner image has been fixed is then discharged to a discharge tray 29 by a discharge roller (not shown).

  The scanner unit 91 is read by the document table 31, an ADF (auto document feeder) 32, a placement table 33 for placing a document conveyed by the ADF, an optical system 34 for reading the document, and the optical system 34. An imaging means 35 comprising a CCD for generating image data of a document is provided.

  When copying using the copying machine 10, the user presses a start key (not shown). When the start key is pressed, the copying machine 10 determines whether or not a document is placed on the document table 31 or the placement table 33. If a document is placed on the document table 31, the copying machine 10 reads the document placed on the document table 31 using the optical system 34. On the other hand, when a document is placed only on the placement table 33, the copying machine 10 reads the document on the placement table 33 with the optical system 34 while using the ADF 32.

  Image data is generated by the imaging means 35 from the document read by the optical system 34.

  Further, when the start key is pressed, the copying machine 10 rotates the photosensitive drum 101 in the arrow Y direction and uniformly charges the surface of the photosensitive drum 101 using the charger 11. When the image data is generated by the image pickup means 35, the copying machine 10 irradiates the photosensitive drum 101 with a laser 12 with a latent image corresponding to the image data, so that the surface of the photosensitive drum 101 corresponds to the image data. A latent image is formed.

  Further, the copying machine 10 rotates the developing sleeve 109 of the developing device 100 to attach toner to the photosensitive drum 101 on which the latent image is formed, thereby visualizing the latent image and generating a toner visual image.

  Simultaneously with the reading of the original and the formation of the toner image as described above, when the start key is pressed, the copying machine 10 transfers the paper stored in one of the paper feeding cassettes 21 and 22 to the paper feeding roller 23, In 24, it sends out to the conveyance path 20. Further, when the toner image formed on the photoconductor drum 101 reaches a position facing the transfer device 13, the copying machine 10 is fed between the photoconductor drum 101 and the transfer device 13 using the transport roller 25. . When the paper passes between the photosensitive drum 101 and the transfer device 13, the toner image is transferred to the paper. Thereafter, the toner image is fixed by the fixing roller 27 and the pressure roller 28 as described above, and the sheet is discharged onto the discharge tray 29.

  The conveying screws 104 and 105 provided in the developing device 100 of the present invention are rotated regularly or constantly by a motor provided in the copying machine 10. When the conveying screws 104 and 105 rotate, the toner (black solid in FIG. 3) in the housing 102 at the time of operation of the developing device 100 is conveyed in the arrow direction (counterclockwise) in FIG. While being stirred. Here, the blade 106 is made of an elastic member, but has such a rigidity that it is not deformed by the pressure applied by the toner during toner conveyance. As the elastic member, for example, silicon rubber, urethane rubber, polyurethane, or the like can be used.

  The blade 106 that urges the toner in the conveying direction at the bottom 301 moves from the bottom 301 to the top 302 where no toner exists by the rotation of the rotating shaft 107. The blade 106 protruding to the upper portion 302 contacts the protrusions 111 and 112 at a position where the toner conveyance is not hindered, that is, a toner-free position (for example, the upper portion 302). Here, the protrusions 111 and 112 are made of a material harder than the elastic member constituting the blade 106, and the blade 106 is deformed when the protrusions 111 and 112 come into contact with the blade 106.

  When the blades 106 come into contact with the protrusions 111 and 112, the toner attached to the blades 106 with which the protrusions 111 and 112 contact is first removed. Then, due to the deformation of the blade 106, the toner adhering to the periphery of the deformed blade 106 is peeled and removed by the deformation. Further, when the protrusions 111 and 112 are separated from the blade 106, the deformation of the blade 106 is eliminated. At this time, the adhered toner is peeled and removed by the return elasticity of the elastic member constituting the blade 106.

  In other words, when the protrusions 111 and 112 contact and separate from the blade 106, it affects the periphery of the contact portion of the blade made of an elastic body, so that the protrusions 111 and 112 do not contact all positions of the blade, The adhered toner can be removed from the entire blade 106. Further, the removal by deformation or elasticity does not deteriorate the toner, that is, the influence of the toner deterioration on the image can be suppressed.

  The positions where the protrusions 111 and 112 are provided and the positions where the protrusions 111 and 112 are in contact with the blades are preferably non-toner positions that do not hinder toner conveyance. For example, it is effective in that a protrusion is provided at a position other than the bottom 301 where toner is present (positioned) during operation, and contact with the blades at a position other than the bottom 301 is not hindering conveyance.

  As the toner-free position, the central wall 110 (the protrusion 112 in FIGS. 1 and 3 and the protrusion 303 in FIG. 3), the upper surface of the housing during operation (the protrusion 111 in FIGS. 1 and 3), or the inner wall of the housing (Protrusions 304 in FIG. 3) and the like.

  Moreover, the structure arrange | positioned corresponding to each blade | wing adjacent in a side view as an example of arrangement | positioning of a longitudinal direction is mentioned. In this configuration, vibration due to return elasticity is generated at the same time, so that it is possible to expect removal due to a synergistic effect of vibration on the entire conveying screw.

  The developing device or the like according to the present invention is useful as a developing device or the like that improves toner conveyance / stirring efficiency by preventing the toner from adhering to the blade without deteriorating the toner.

1 is a schematic diagram of a copying machine in which a developing device according to an embodiment is built. The top view of a developing device. Sectional drawing of a developing device. The top view of the conventional image development apparatus. Sectional drawing of the conventional image development apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Developing device 102 Housing 103 Developing roller 104, 105 Conveying screw 106 Blade 110 Restricting member 111, 112 Projection

Claims (6)

A housing in which toner is held;
A conveying screw that is disposed in the housing and includes a rotating shaft and a blade that is disposed on the rotating shaft and conveys the toner by rotation of the rotating shaft;
A rotatable developing roller that contacts the exterior of the housing and the interior of the housing, and that acquires toner from the conveying screw;
The blade is composed of an elastic member,
The housing is provided with a projecting portion on an inner surface of the housing that includes a protrusion that contacts and separates the blade in a deformable manner according to the rotation of the rotating shaft.   The developing device according to claim 1, wherein the protrusion is provided at a toner-free position that does not inhibit toner conveyance. A plurality of the conveying screws are disposed on one side of the developing roller, and the longitudinal central portions of the conveying screws are separated by a central wall. The protrusion is provided on the central wall. Item 3. The developing device according to Item 2.   The developing device according to claim 2, wherein the protrusion is provided on an upper surface of the housing during operation of the developing device.   The developing device according to claim 1, wherein the protrusion is made of a hard material as compared to the blade. An image forming apparatus comprising the developing device according to claim 1.

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