JP4556606B2 - Developer - Google Patents

Description

  The present invention relates to a developing device in an electrophotographic recording apparatus employed in a facsimile machine, a copying machine, a printer (including these multifunction machines), and the like.

  In the electrophotographic recording apparatus as described above, the electrostatic latent image formed on the surface of the photoconductor (drum) is developed by a developing device based on the image information to form a toner image, and this toner image is recorded on the recording sheet. The toner image is transferred to (recording paper), and then this unfixed toner image is fixed on the recording sheet as a permanent image by a fixing device. The developing device stores powder toner in a developing device housing, supplies the toner to the developing roller while constantly or periodically stirring the toner in the housing, and rolls the developing roller on the surface of the photosensitive member. The electrostatic latent image is developed with toner.

  The toner is agitated in the housing by an agitating member that is supported on the wall of the housing so as to be axially rotatable. The example shown in FIG. 4 shows an example of a conventional support structure for a stirring member in the developing device housing wall. In the illustrated example, the stirring member 100 includes a stirring shaft 101 and a stirring blade (stirring piece) 102 attached to the stirring shaft 101 along the axial direction. The agitation shaft 101 is supported on the wall 104 of the developing device housing 103 so as to be rotatable about the shaft. A gear 105 is attached to one end of the agitation shaft 101. 102 rotates around the shaft together with the stirring shaft 101, and the powder toner t... Accommodated in the housing 103 is stirred. A shaft hole 106 through which the stirring shaft 101 is inserted in the support portion of the stirring shaft 101 in the housing wall portion 104, and a circular shape that is concentric with the shaft hole 106 on the outer surface of the housing wall portion 104 and larger in diameter than the shaft hole 106. A recess 107 is formed, and a sponge-like elastic seal member 108 is interposed between the circular recess 107 and the stirring shaft 101.

  The elastic seal member 108 also functions as a bearing portion of the stirring shaft 101 and functions to prevent the toners t in the housing 103 from leaking outside. The elastic seal member 108 is interposed between the circular recess 107 and the stirring shaft 101 in an elastically compressed state. When the rotational driving force from the gear 105 is applied to the stirring shaft 101, the vibration is caused by the vibration of the stirring shaft 101. And the elastic seal member 108 may change, and the toner t may intrude into the contact pressure portion of the two and leak to the outside. In particular, polymerized toners that have been frequently used recently have a very small particle size and have a shape close to a true sphere, and thus behave like a liquid and easily flow along a stirring axis. The leak became a problem.

In Patent Document 1, oil seals having different diameters are used, and a stirrer shaft is provided with a step portion having a large and small diameter, and the oil seal having a large diameter is mounted on the shaft portion, and the toner is attached to the step portion. A technique for preventing the outflow of the battery is disclosed.
Japanese Patent Laid-Open No. 11-174836

  In the technique disclosed in Patent Document 1, two oil seals having different diameters are used, and the shape of the shaft portion for mounting the oil seals is stepped in steps. Accordingly, each of the oil seals sequentially attached from the front side needs to be prevented from coming off, and the stirring shaft or the bearing portion of the toner container must be subjected to complicated processing. In addition, since two expensive oil seals are used, combined with complicated processing, the manufacturing cost increases.

  SUMMARY An advantage of some aspects of the invention is that it provides a developing device including a stirring member that has a simple bearing structure and an excellent toner leakage prevention function. .

The developing device according to the present invention is a developing device including a stirring member for stirring the powder toner accommodated in the developing device housing, and the stirring member rotates on a housing wall portion of the developing device housing. A stirrer shaft supported in a possible manner and a stirrer piece attached to the stirrer shaft. A small-diameter concave stepped portion is formed at both ends of the stirrer shaft protruding from the housing wall. A step wall portion is formed at both axial end portions of the step portion, and an annular elastic seal member is interposed between the concave step portion and the housing wall portion so as to be in a contact pressure state. And Furthermore, the support portion of the stirring shaft in the housing wall portion includes a shaft hole through which the stirring shaft is inserted, and a circular recess that is concentric with the shaft hole and larger in diameter than the shaft hole on the outer surface of the housing wall portion. The elastic sealing member is formed, and is interposed between the circular recess and the recessed step.

  According to the developing device of the present invention, a concave step portion having a small diameter is formed in the supported portion of the housing wall portion of the stirring shaft, and an elastic seal member is interposed between the concave step portion and the housing wall portion. Therefore, the toner flowing along the peripheral surface of the stirring shaft is blocked by the elastic seal member, and the toner partially falling into the recessed step portion is blocked by the step wall portion of the recessed step portion. Therefore, further flow is prevented, and leakage of the toner to the outside is surely prevented. Since the seal member is made of an elastic material, the mounting to the concave step portion is easily performed by a press-fitting operation accompanied by elastic deformation, and no special means for preventing the removal is required. Since the part can be cut by general-purpose machining means such as a lathe, the machining cost does not increase.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration of a recording unit provided in an image forming apparatus employing a developing device of the present invention, FIG. 2 is a cross-sectional plan view taken along the line XX of FIG. 1, and FIG. 3 is an enlarged view of a Y part of FIG. It is.

  An image forming apparatus 1 shown in FIG. 1 includes an electrophotographic recording unit 2 employed in a facsimile machine, a copying machine, a printer (including these multifunction machines), and its peripheral devices. A recording unit equipped with a paper feed cassette 3 is provided below the recording unit, and a large number of recording papers (recording sheets) P are stored in the paper feed cassette 3. The recording paper P is fed out from the paper feeding cassette 3 one by one by the paper feeding roller 4, and then registered by the registration roller device 5, and the toner image formed on the photosensitive drum 6 of the recording unit 2 is synchronized with the timing. Paper is fed. It is also possible to install a plurality of paper feed cassettes in a stack in the paper feed unit, and select and feed a specified size of recording paper from any paper feed cassette.

  A recording unit 2 is disposed above the paper feeding unit (on the downstream side in the flow of the recording paper P), and above the recording unit 2 (same as above), a heating roller 7a and a pressure roller 7b. Are installed so as to be in pressure contact with each other. The cleaning roller 7c is installed in a state of being pressed against the peripheral surface of the heating roller 7a. In this fixing device 7, the toner melted by heat is solidified and fixed on the recording paper P while the recording paper P onto which the toner image is transferred from the photosensitive drum 6 is nipped between the rollers 7 a and 7 b and conveyed. Then, the recording paper P on which the permanent image is formed is discharged to the discharge tray 9 by the discharge roller device 8. The toner adhering to the heating roller 7a is sequentially removed by a cleaning roller 7c that rotates in contact with the photosensitive drum 6.

  As in the case of a recording apparatus using a general electrophotographic system, the recording unit 2 includes a photosensitive drum 6, a charging member 10, optical writing, which are sequentially arranged around the photosensitive drum 6 along its rotation direction. A member 11, a developing device 12, and a transfer device (transfer roller) 13 are included. The illustrated developing device 12 includes a toner bottle 14, a main body housing (developer housing) 15 that stores toner replenished from the toner bottle 14, a stirring member 16 that stirs the toner t in the main body housing 15, and It comprises a developing roller 17 that rotates close to the surface of the photosensitive drum 6, but does not exclude other developing devices. In this recording unit 2, the surface of the rotating photosensitive drum 6 is uniformly charged by the charging member 10, and then light irradiation based on image information is performed by the optical writing member 11, so that the surface of the photosensitive drum 6 is applied. An electrostatic latent image is formed. Next, toner is supplied to the electrostatic latent image by the developing roller 17, and the toner is attached to form a visible image of the toner on the surface of the photosensitive drum 6.

  The toner image formed on the surface of the photosensitive drum 6 has a predetermined value on the transfer roller 13 from the back side of the recording paper P at the position where the recording paper P is nipped and conveyed by the photosensitive drum 6 and the transfer roller 13. When the voltage is applied, the recording material P is transferred and transferred. The recording paper P to which the toner image has been transferred passes through the fixing device 7, whereby the toner image is fixed as a permanent image, and is discharged to the discharge tray 9 by the discharge roller device 8. The toner remaining on the surface of the photosensitive drum 6 after the transfer process is scraped off by a rotating brush 18a or a blade (not shown) provided in the cleaning device 18 and is not shown by a screw-type conveying member 18b. Housed in a toner box.

  Next, the configuration of the developing device 12 will be described in detail. The toner t replenished from the toner bottle 14 that rotates continuously or intermittently is stored in the main body housing 15. In the main body housing 15, the toner t is conveyed to the developing chamber 17 a while being agitated by the rotation of the agitating member 16, and the electrostatic latent image on the surface of the photosensitive drum 6 is developed by the developing roller 17 that rotates in the vicinity of the photosensitive drum 6. Is developed with toner. The developing roller 17 is rotated by a rotational driving force transmitted from a driving source (not shown) via a gear 17b fixed to one end thereof.

  The stirring member 16 includes a stirring shaft 16a and a stirring blade (stirring piece) 16b attached to the stirring shaft 16a along the axial direction. The agitation shaft 16a is supported on the wall 15a of the main housing 15 so as to be rotatable. A gear 16c is attached to one end of the agitation shaft 16a, and the agitation blade 16b is transmitted by power transmission from a drive source (not shown) to the gear 16c. Together with the agitation shaft 16a, it rotates around that axis, and the powder toner t ... accommodated in the main body housing 15 is agitated. A shaft hole 15b through which the agitation shaft 16a is inserted is provided at both end support portions of the agitation shaft 16a in the housing wall 15a, and a circular recess that is concentric with the shaft hole 15b and larger in diameter than the shaft hole 15b on the outer surface of the housing wall 15a. 15c is formed, and a sponge-like elastic seal member 19 made of an independent foamed resin or the like is interposed between the circular recess 15c and the stirring shaft 16a.

  The interposed portion (supported portion) of the elastic seal member 19 at both ends of the agitation shaft 16a is a concave step portion 16d cut to a smaller diameter than the portion located in the main body housing 15, and this concave step. Step wall portions 16e are formed at the left and right ends of the portion 16d. The elastic seal member 19 is formed in an annular shape, and is fitted from both ends of the stirring shaft 16a with elastic deformation, so that the inner wall of the circular concave portion 15c of the housing wall portion 15a and the formation surface of the concave step portion 16d are formed. Is elastically fitted. Thereby, the stirring shaft 16a is supported by the main body housing 15 so as to be capable of rotating the shaft, with the elastic seal members 19 at both ends as bearing members. By attaching the gear 16c to one end side of the stirring shaft 16a, a rotation transmission system of the stirring member 16 is formed. Thus, since the elastic seal member 19 has elasticity, the circular recess 15c and the recessed step portion 16d can be easily mounted by a press-fitting operation accompanied by elastic deformation. In addition, no special means for preventing the elastic seal member 19 from coming off is required, and the concave step portion 16d can be cut by a general-purpose processing means such as a lathe, resulting in an increase in processing cost. There is nothing.

  In the mounting state as described above, the elastic seal member 19 is in a pressure contact state with the inner wall of the circular recess 15c and the formation surface of the recessed step portion 16d. Therefore, even if the toner t ... accommodated in the main body housing 15 tries to flow toward the outside of the housing along the peripheral surface of the stirring shaft 16a in the shaft hole 15b, the stirring shaft 16a is moved by the elastic seal member 19. The flow along is blocked. In the case of the polymerized toner having high fluidity as described above, when the contact pressure changes as the stirring shaft 16a rotates, a part of the toner t enters the contact pressure portion and falls into the concave step portion 16d. However, further flow is prevented by the step wall portion 16e, and leakage of the toners t to the outside of the developing device 12 is surely prevented.

  In the above example, the elastic seal member 19 substantially serves as the bearing member of the stirring shaft 16a. However, the present invention is also applied to a bearing mechanism in which a bearing portion is provided outside the elastic seal member 19. Needless to say. In this case, since the elastic seal member 19 prevents the toner from entering the sliding contact portion of the bearing portion, the load torque of the sliding contact portion due to the toner penetration does not increase. Moreover, although the example in case the stirring part piece 16b is a stirring blade was shown, this may be a wire-like thing. Further, the developing device of the present invention is applicable to both monochrome and color electrophotographic image forming apparatuses, and the layout configuration of the image forming apparatus 1 is not limited to that shown in FIG. Needless to say, the present invention can also be applied to an electrophotographic apparatus for recording on an OHP sheet.

FIG. 4 is an explanatory diagram illustrating a configuration of a recording unit in an image forming apparatus employing the developing device of the present invention. FIG. 2 is a cross-sectional plan view taken along the line XX of FIG. It is an enlarged view of the Y section of FIG. It is the same figure as FIG. 3 which shows an example of the conventional developing device.

Explanation of symbols

12 developing device, 15 main body housing (developing device housing),
15a housing wall, 15b shaft hole, 15c circular recess,
16 stirring member, 16a stirring shaft, 16b stirring blade (stirring piece),
16d concave step, 19 elastic seal member.

Claims (2)

A developing device including a stirring member for stirring the powder toner accommodated in the developing device housing,
The stirring member, the developing device and a stirring shaft that is pivotally supported on the housing wall of the housing, become more and stirring piece attached to the stirring shaft,
Wherein at both ends projecting from said housing wall portion of the agitating shaft are formed step wall portion in the axial direction both ends of the recessed step with recessed step portion of the small-diameter is formed, the said recessed step portion housing wall a developing unit annular elastic seal member so that the contact pressure state is characterized in that it is interposed between the parts. Wherein the supporting portion of the stirring shaft in the housing wall, a shaft hole for inserting the stirring shaft, and the housing wall outer surface to said axial hole of concentric and circular recess of larger diameter than the shaft hole is formed ,
The elastic sealing member, the developing device according to claim 1, characterized in that it is interposed between the circular recess and the recessed step.

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