Feed roller for mixing a powder

Abstract: In a feed roller for mixing a developer and feeding it to a developing roller, a first mixing wing (40) parallel to a rotating shaft (43) is provided, a second spiral-shape mixing wing (41) is diagonally provided in a manner to cross the first wing (40), and a spiral-shape groove (42) for feeding a powder is formed on the one side located on the forward section with respect to rotating direction and being the powder scraping-up side of the both sides of said second mixing wing (41), along said second mixing wing (41), so as to enhance the feed performance, lateral-mixing performance and lateral-feed performance of the feed roller.

Description: The invention relates to a feed roller for mixing a powder such as a developer in an image-forming apparatus according to the preamble portion of claim 1. In the prior art, as a mixing roller for mixing a developer in developing devices arranged in image-forming apparatuses or as a feed roller for feeding the developer to a developing roller, the following rollers have been used: a. A vibration-type mixing roller whose spiral-shape mixing wing has a cutout as shown in Fig. 1 (Japanese Laid-open Patent Publication No. 197026/1986); b. A screw-type spiral roller as shown in Fig. 2 (Japanese Laid-open Utility Model Publication No. 87735/1987 & US-A-4711551 which is the basis of the preamble portion of claim 1) ; c. A mixing roller having a mixing wing parallel to a rotating shaft thereof and a spiral groove to prevent pressure rise as shown in Fig. 3 (Japanese Laid-open Utility Model Publication No. 47353/1988); d. A roller having a feed roller with a flat wing and including a spiral roller near the feed roller as shown in Fig. 4 (Japanese Laid-open Utility Model Publication No. 184068/1985); e. A feed roller having an opening located on the backward section with respect to the rotating direction of a spiral-shape mixing wing as shown in Fig. 5 (Japanese Laid-open Utility Model Publication No. 53459/1987); and f. A feed roller having a spiral wing having a rectangular plane member as shown in Fig. 6 (Japanese Laid-open Utility Model Publication No. 140969/1985). However, among the above-described mixing rollers or feed rollers, the spiral-shaped rollers as shown in the items a, b and e have had a problem that they have a small capability to feed a developer to a developing roller, and the roller having an auxiliary lateral-feed mechanism as shown in the item d or the one having a mixing wing parallel to a rotating shaft thereof as shown in the item c have a problem that they have a poor lateral mixing performance and particularly the one of spiral-shape as shown in the item f has a problem that they scrapes up a developer diagonally to a developing roller. Also, as another type of roller, a roller having a shaft and lateral-feed blades mounted on the shaft is available. The lateral-feed blades are designed to laterally feed a developer and mix the developer so as to keep proper fluidization balance of the developer. For example, as disclosed in Japanese Laid-open Patent Publication No. 21468/1989, a roller is known in which the screw pitch of lateral-feed blades S is made large on the start side in the screw-conveyance direction and small on the end side (see Fig. 7). However, such prior art mixing rollers have had a problem that, since their lateral-feed blades are continuous spiral-shape blades, when an attempt is made to change variously their pitch with shaft position, the density of blades at a place of large pitch becomes inevitably coarse, thereby causing the developer lateral-feed force not to be increased. The object of the invention is to realize a feed roller for mixing a powder such as a developer in an image forming apparatus which feeds a sufficient quantity of developer to a developing roller, improves lateral-mixing performance and has an excellent lateral-feed performance. The object is solved according to the features of claim 1. The dependent claims show advantageous development and further embodiments of the invention. According to the invention a first mixing wing is provided parallel to a rotating shaft and a second spiral-shaped mixing wing is provided diagonally to the shaft, crossing each other. A spiral-shaped groove for feeding a powder is formed with respect to the rotating direction of the second mixing wing. The invention is arranged in such a manner as described above, so that the first mixing wing feeds vertically a powder to the next process while mixing the powder in the rotating direction, and the second mixing wing laterally feeds the powder while mixing the powder in the lateral direction. Further, the groove for feeding the powder causes the sliding of the powder on the second mixing wing to become better, thereby allowing the lateral-feed capability to be improved. The following drawings show examples of preferred embodiments of the invention. Figs. 1 through 7 are views of prior art feed rollers. Fig. 8 is a schematic sectional view of an image-forming apparatus using a feed roller according to the present invention. Fig. 9 is a sectional view of a developing device of the image-forming apparatus. Fig. 10 (a) is a side view of one embodiment of a feed roller according to the present invention. Fig. 10 (b) is a front view of the embodiment. Fig. 11 is a front view of the feed roller shown in Fig. 10 (b) when rotated about 45 degrees. Based on the drawings showing embodiments, the invention is described hereinafter. First an image-forming apparatus using a feed roller according to the present invention is and then a developing device of the apparatus, arranging the feed roller is described. Fig. 8 is a schematic sectional view showing an image-forming apparatus using a feed roller according to the present invention. On the upper part of the apparatus, a manuscript placing plate 2 for placing a manuscript, a manuscript cover 1, and an optical system 200 including a lamp 3 and reflection mirrors 4 are provided. The optical system 200 moves in such a manner as to scan a manuscript along the manuscript placing plate 2. On the periphery of an image carrier 5, a main electrifier 6 for electrifying the image carrier 5, a developing device 7 for toner-developing a latent image on the image carrier 5 formed by being exposed to the image light entered from the optical system 200, a transfer device 9 for transferring the toner-image-developer to a sheet 8, a separator 10 for separating the sheet 8 from the image carrier 5, a cleaner 11 for cleaning a toner remaining after the transferring, and the like are arranged. On the upstream side of the transfer device 9, a conveyance path 14 for conveying the sheet 8 from a sheet feed cassette 12 for feeding the sheet 8 or from a hand insertion tray 13 is provided. Also, on the conveyance path 14, a sheet feed roller 15, a conveyance roller 16, a resist roller 17 and the like are arranged, and a sheet guide plate 18 is provided directly upstream the transfer device 9. On the downstream side of the separator 10, a conveyance belt 19 is provided, which conveys the separated sheet 8 to a thermal fixer 20. The thermal fixer 20 melts and fixes a toner image on the sheet 8. The toner-fixed sheet 8 is discharged onto a discharge tray 21. With reference to Fig. 9, the developing device of the image-forming apparatus is described hereinafter. In Fig. 9, a toner supply roller 30 for supplying a toner is provided on the diagonally upper side within the developing device 7. Under the toner supply roller 30, a mixing roller 32 for mixing a developer X returned from a pass partition plate 31 with the toner from the toner supply roller 30 is provided; a feed roller 33 for feeding the developer X mixed by the mixing roller 32 to a developing roller 34 is provided on the image carrier 5 side; and the developing roller 34 is provided close to the image carrier 5. On the developing device 7, a toner sensor 35 is arranged, and an ear cut plate stay 36 and a developing-slit plate 37 are provided. Also, a developing housing 38 covers the developing device 7. The operation in the developing device 7 is described hereinafter. The developer X is mixed by the mixing roller 32 and fed to the feed roller 33. The feed roller 33 feeds a new developer X mixed to the developing roller 34. And, the developer X having not ridden on the developing roller 34 by the ear cutting of the ear cut plate stay 36 is fed onto the pass partition plate 31. Then, the developer X having passed through the pass partition plate 31 is returned to the mixing roller 32. With reference to Figs. 10 and 11, one embodiment of the feed roller 33 which is provided on the developing device 7 in accordance with the present invention is described hereinafter. Fig. 10 (a) is a side view of the feed roller 33, and Fig. 10 (b) is a front view of the roller. Fig. 11 is a front view of Fig. 10 (b) when rotated about 45 degrees. In Figs. 10 and Fig. 11, a first mixing wing 40 is provided parallel to a rotating shaft 43, and the three-step first mixing wings 40, 40 and 40 are seen in both Fig. 10 (b) and Fig. 11. A second mixing wing 41 is diagonally provided and of spiral-shape. The first mixing wing 40 and the second mixing 41 are formed crossing each other in the lateral direction (axially). A spiral-shape groove 42 for moving a developer is formed on the one side located on the forward section with respect to rotating direction (on the powder scraping-up side) of the both sides of the second mixing wing 41, along the second mixing wing 41. The operation of the above-described embodiment according to the present invention is described hereinafter. The first mixing wing 40 can feed vertically a developer to the developing roller 34. The second mixing wing 41, though of course mixes the developer and feeds it in lateral direction, is provided with the groove 42 for feeding the developer, so that the sliding of the developer on the second mixing wing 41 becomes better, thereby causing the developer lateral-feed capability to be improved (see arrow A). The adjustment of the clearance of the groove 42 for feeding a developer allows the lateral-feed of lateral mixing to be adjusted. Further, even after the completion of a mold, a little adjustment can be performed. Also, where, using the feed roller 33 and a spiral-shape roller having a capability of lateral-feed in the opposite direction to the feed roller 33, mixing is made balanced, the apparatus performance is less affected by developer toner concentration difference and environmental conditions (such as humidity and apparatus installing condition). The feed roller in the present invention includes the mixing roller in addition to the feed roller in a narrow sense. Also, although, in the above-described embodiment, small block units are combined to form the feed roller , of course an integrally molded feed roller may be accepted. The feed roller according to the present invention can be used for apparatuses for mixing a powder besides image-forming apparatuses. As described above, the present invention is such that the first mixing wing provided parallel to the rotating shaft and the second spiral-shape mixing wing provided diagonally to the shaft are formed crossing each other, and the spiral-shape groove for feeding a powder is formed on the one side located on the forward section with respect to rotating direction of the both sides of the second mixing wing, along the second mixing wing, so that the groove for feeding a powder causes the sliding of the powder on the second mixing wing to become better, thereby allowing lateral-mixing performance and lateral-feed performance to be improved. Further, the first mixing wing can feed a sufficient quantity of powder to the roller of the next process.

Claims: Feed roller for mixing a powder such as a developer in an image forming apparatus, comprising a first mixing wing (40) provided parallel to a rotating shaft (43), and a second spiral-shaped mixing wing (41) provided diagonally to the shaft, said two wings (40, 41) are crossing each other, characterized in that a spiral-shaped groove (42) for feeding the powder is formed between the first mixing wing (40) and the second mixing wing (41) along the forward side of said second mixing wing (41) with respect to the rotating direction of the shaft (43) and being the powder scraping-up side of the second mixing wing (41). Feed roller according to claim 1, characterized in that the first mixing wing (40) is formed for vertically feeding the powder. Feed roller according to claim 1 or 2, characterized in that the second mixing wing (41) is formed for mixing the powder and feeding it in a lateral direction. Feed roller according to claims 1 to 3, characterized in that the groove (42) is provided for improving the sliding of the powder on the second mixing wing (41) , and for improving the lateral-feed capability. Feed roller according to claims 1 to 4, characterized in that the groove (42) has a clearance which is adjustable for amending the lateral-feed thereof. Feed roller according to claims 1 to 5, characterized in that the feed roller is composed from small block units which combine to form the feed roller (33).

Inventors: ISHIDA HIDEKI, ISHII YOSHIFUMI, KITAGAWA SHOICHI, KUSUMOTO HIROSHI, MIYAMOTO NARUYUKI, ISHIDA, HIDEKI, ISHII, YOSHIFUMI, KITAGAWA, SHOICHI, KUSUMOTO, HIROSHI, MIYAMOTO, NARUYUKI
Applicants: MITA INDUSTRIAL CO LTD, MITA INDUSTRIAL CO., LTD.
Application year: 1990
Main classification: G03G15
IPC codes: G03G15, B01F15, B01F7