GB2257534A - Scraper structure for electrophotographic development unit - Google Patents

Abstract

A scraper structure for an electrophotographic development device (65) which supplies toner to a development roller upon rotation of the scraper structure, comprises a drive shaft (708) on which is mounted a plurality of blocks 70A using shafts 71 engaging slits (71A) and projections (718) so that the units are at 900 to each other, each block having blades (74), each of which is symmetrically formed across the central line of the shaft, extends along a plane slanted to the central axis of the shaft by a predetermined angle as arms (72, 73) are bent in a direction opposite to the rotational direction of shaft (70B), and intersects the central axis of the shaft at the center in the longitudinal direction of the blade. This means toner in the vessel (65A) is moved alternately right and left to even out the supply to the development roller. <IMAGE>

Description

SCRAPER STRUC'1'URE FOR l)EVEL,OPMENT UNIT The present invention relates to a scraper structure for a development unit disposed in a developer accommodation unit of the development unit making use of electrophotography for supplying toner to a development roller by being rotated.

Conventionally known is an image formation apparatus such as an electrophotographic copy machine, laser beam printer and the like, making use of socalled electrophotography, wherein an electrostatic latent image is formed by exposing the surface of a piloto-conductive drum formed of a photoconductive material. toner is adhered onto the latent image and developed, and tiiis toner is transferred onto a recording paper and fixed by a fixing unit.

Although various systems are employed as a development mechanism for the electrophotograpijy and a different developer is used for a different system, a widely used development; unit is arranged such that; c}larged toner is transferred to a development area by a roller (development roller) disposed in close proximity to a photoconductive drum.

In this type of the development unit, the development roller is disposed adjacent to a vessel shaped developer accommodation unit and a scraper being rotated for supplying a developer to the development roller is contained in the developer accommodation unit.

It is therefore an object of the present invention to provide a scraper for a development unit by which a developer is moved in the longitudinal direction of a development roller r in a developer accommodation unit to thereby solve the uneven distribution of the developer in the longitudinal direction of the developer accommodation unit, so that the developer is evenly distributed in the longitudinal direction of the development roller, toner is permitted to be rationally supplied, and an effectively usable space in the developer accommodation unit can be increased.

According to the present invention there is provided a scraper structure provided in a toner accommodation vessel for a development device which includes a development roller therein, so as to extend substantially in parallel with the development roller, for supplying the toner in said toner accommodation vessel to the development roller upon rotation of said scraper structure, the scraper structure comprising a shaft extending substantially in parallel with the development roller; and a plurality of blades each of which is symmetrically formed across the central line thereof, extending along a plane slanted to said central axis of said shaft by a predetermined angle, and intersecting the central axis of said shaft substantially at the center in the longitudinal direction of said blade, said plural blades being disposed in series in the axial direction of said shaft with the phases of said blades dislocated by a predetermined angle.

With this arrangement, the toner in the toner accommodation unit is slightly moved alternately in the right and left sides in the axial direction, and when the toner is unevenly distributed in the longitudinal direction of the toner accommodation unit, the toner is slightly moved from the portion where a larger amount of it is located to the portion where a smaller amount of it is located, whereby an uneven distribution of the toner in the longitudinal direction of the toncr accommodation unit can be solved. As a result since the remaining toner is evenly distributed in the longitudinal direction of the toner accommodation unit, toner can be rationally supplied, an effectively usable space in the toner accommodation unit is increased, and freedom of disposition of a toner sensor is improved.

An example of the present invention is described in detail below, with reference to the accompanying drawings, in which: Figure 1 is a schematic longitudinal cross sectional view of an electrophotographic facsimile apparatus provided with a development unit to which a scraper structure embodying the present invention is applied; Figure 2 is a perspective view of the development unit of Figure 1; Figure 3 is an exploded perspective view of the scraper of Figure 2; Figure 4 is a diagram explaining the operation of the scraper; and Figure 5 is a diagram showing the state of the scraper rotated by 90 from the state shown in Figure 4.

One embodiment of a scraper structure of the present invention will be described below with reference to tie attached drawings.

Figure 1 is a schematic longitudinal cross sectional view of an electrophotographie facslmile apparatus provided with a development unit to which a scraper structure embodying the present invention is applied, wherein the right side corresponds to the front side of the apparatus.

As shown in Figures 1 and 2, the facsimile apparatus comprises a main body 10 and an upper component 20 as a member covering the front upper portion of the main body 10. A paper feed unit 30 is disposed on the upper rear portion of the main body 10 for feeding or introducing recording papers on which received information is to be recorded and documents from which information to be transmitted is read to the apparatus.

The upper surface of the upper component 20 gradually inclines downward toward the front end of the apparatus and an operation unit 23 including a display panel, operation buttons and the like is disposed thereon.

A reading head 50 is contained in the upper component 20, a document to be transmitted is fed from the paper feed-unit 30 through the upper component 20, and the information recorded on the document is read by the reading head 50.

A recording unit 60 provided with various operation mecllanisms for electrophotography is accommodated in the main body 10 and the recording papers to which received information is to be output are fed from the paper feed unit 30 between the main body 10 and the upper component 20 to the recording unit 60 where the received information is recorded onto them by the recording unit 60.

The respective units will be sequentially described in detail below.

The paper feed unit 30 is composed of a cassette mounting unit 31 having a recording paper cassette 40 detachably mounted to the recording paper introduction portion of the paper feed unit 30 and a document holder 32 for documents to be transmitted located at the front edge (right side in Figure 2) of the cassette mounting unit 31. The cassette 40 contains recording paper onto which received information is recorded.

The cassette mounting unit 31 has a recording paper introduction roller 33 disposed at a position corresponding to the upper extreme end of the recording paper contained in the recording paper cassette 40 mounted to the cassette mounting unit 31. The recording paper introduction roller 33 is rotated by a drive motor (not shown).

The upper component 20 comprises an arm z which extends from a panel frame 21 as the framework of the upper component 20 toward the rear end of the apparatus and is swingably supported by a swing shaft 11 located at the upper rear portion of the main body 10. An operation panel 22 constitutes the upper surface of the upper component 20 and is swingably supported by a pin 25 at the end of the upper component 20 on the paper feed unit 30 side. Thus in this arrangement the upper component 20 can be swingingly opened and closed together with the operation panel 22 and the operation panel 22 can be swlngingly opened and closed independently of the upper component 20.

An operation panel base plate 22A is attached to the operation panel 22 along the inside (lower side) thereof. An upper document guide plate 22B is disposed inwardly of the operation panel base plate 22A (the main body 10 side) , arid the reading head 50 Is disposed in close proximity to the document introduction side of tile upper document guide plate 22B (the paper feed unit 30 side).

The reading head 50 is composed of a close contact type reading sensor 51 and a document introduction roiler 52,both supported by a head frame 53, and the operation panel 22 is swingably supported by the pin 25 by which the panel frame 21 is also supported, with the document introduction roller 52 located at the paper feed unit 30 side.

The panel frame 21 has a lower document guide plate 2113 located at a position corresponding to the upper document guide plate 2213, a feed roller 26 located at a position corresponding to the reading sensor 51 of the reading head 50, and a lower introduction unit guide 21C located at a position corresponding to the reading head 50, respectively.

The rear end (the side adjacent to the paper feed unit 30) of the lower introduction unit guide 21C is formed as an inclined surface contiguous to the document holder 32 of the paper feed unit 30. A press and support plate 21D is disposed at a position corresponding to the document introduction roller 52 of tlie lowcr introduction unit guide 21C such that tlle press arid support plate 21D is pressed and urged against the document introduction roller 52 from the lower side thereof by an elastic return force.

Furthermore, a pair of paper discharge rollers 27 are disposed substantially midway in the longitudinal direction of the lower document guide plate 21B and are composed of a lower roller 27A slightly projecting above the upper surface of the lower document guide plate 21B and an upper roller 27B abutting against the projecting upper surface of the lower roller 27A.

Witii the arrangement of the operation panel 22 and panel frame 21, a document path is formed between the operation panel 22 side (this reading sensor 51 and upper document guide plate 22B) ad the panel frame 21 side (the lower introduction unit guide 21C, press and support plate 21D and lower document guide plate 21B). The document introduction roller 52 of the reading head 50, the feed roller 26 of the panel frame 21 and the lower roller 27B of the pair of paper discharge roller 27 are driven by a drive motor (not shown) at a predetermined circumferential speed to feed a document placed on the document holder 32 through the document path along a feed path shown by a dot-dash line in Figure 1 and information recorded on the document is recorded by being read by the reading head 50. More specifically, the document placed on the document holder 32 is introduced into the upper component 20 by the document introduction roller 52 and the information recorded on the upper surface of the document is read by the reading sensor 51 while the document is being fed by the feed roller 26. The document is then fed by the pair of discharge rollers 27 and discharged through the front end of the main body 10.Note, as described above, the reading head 50 is disposed above the document feed path in this arrangement and a document is placed on the document holder 32 with the information recorded surface thereof (the surface from which information is to be read) facing upward. Thus the document is fed, the information is read and the document is discharged, in this state.

On the other hand, the main body 10 includes the recording unit 60 provided with the various operation mechanisms for electrophotography, as described above.

More specifically, there are disposed a cleaning mechanism 62 for cleaning toner remaining on the surface of a photoconductive material on the surface of a photoconductive drum 61, a corona charger 63 for uniformly charging the photoconductive material on the surface of the pllotoconducti.ve drum 61, and a scanning optical unlit 64 for exposing and scanning tulle charged surface of tiie photoconductive drum 61 with a laser beam which is turned ON and OFF based on image information.A development unit 65 forms a toner image by adherlng toner to the portion of the photoconductive material where a latent image is formed by í;lle removal of electric charge therefrom by exposure, and a transfer charger 66 transfers the toiier image onto a recording paper by charging the recording paper. The photoconductive drum 61 is driven at a predetermined circumferential speed by a drive motor (not shown), and a fixing unit 67 is disposed at a position toward which tile recording paper on which the toner image is transferred by the transfer charger 66 is fed.

The cleaning mechanism 62 includes a blade formed of an elastic member and abutting against the surface of tiie photoconductive drum 61 and is arranged in a photoconductive drum unit 61A by being mounted on a single frame together with the photoconductive drum 61 and corona charger 63.

The development unit 65 is composed of a toner accommodation vessel 65R and a development roller 6513.

The former includes a toner cartridge 65C detachably mounted tiiereon ad the latter has a cyllndrical sleeve into which a magnet roller is inserted and rotatably supported at an end of the toner accommodation vessel 65A. The toner accommodation vessel 65A has a support shaft 12 which is parallel with t-he development roller 65B and located at an upper position of the vessel 65A corresponding to the right side of the toner cartridge 65C in Figure 2.The development unit 65 is supported by the chassis (not shown) of the main body 10 and swung about the support shaft 12 with the development roller 65E in close proximity to the photoconductive drum 61 on the rear side thereof with respect to the apparatus in such a manner that the opposite ends of the support shaft 12 are engaged with U-shaped grooves which are formed to the chassis and open upward.

The scanning optical unit 64 is composed of the respective components of the scanning optical system for scanning the surface of the photoconductive drum 61 with a laser beam which is turned ON and OFF based on image information and these components are integrally arranged by being mounted on a unit frame 64A.

Further, the scanning optical unit 64 is mounted on the lower surface of a main body chassis 10A below the development unit 65 and paper feed unit 30. A laser beam from tulle scanning optical unit 64 passcs between the corona clsarger 63 and the development unit 65 and irradiates the photoconductive drum 61 (for scanning the photoconductive drum 61).

The transfer charger 66 is supported above the photoconductive drum 61 by the panel frame 21 of the upper component 20.

The fixing unit 67 is composed of a heat roller 67A heated to a predetermined temperature and a press roller 67B located obliquely upward of the heat roller 67A on the front end side of the apparatus, pressed against the heat roller 67A, and fixed on the upper surface at a predetermined position of the main body chassis 10A. The heat roller 67A is rotated at a circumferential speed in syndhronism with that of the photoconductive drum 61, and thus the fixing unit necessarily feeds a recording paper in addition to carrying out a fixing action.

Further, the inclined upper surface of the toner cartridge 65C of the development unit 65 is disposed in close proximity to an upper recording paper guide plate 21E disposed on the lower side of the lower introduction unit guide 21C of the panel frame 21 of the upper component 20 with a predetermined space defined therebetween, A recording paper feed path regulation plate 21E disposed on the lower surface of the lower document guide plate 21B of the panel frame 21 is located above the photoconductive drum 61 and the fixing unit 67 and therebetween and is formed to an arc shape directed from the transfer unit 66 toward the fixing unit 67 located obliquely downward of the transfer charger 66 on the front end side of the apparatus.

Furtilermore, a pair of rollers 69 is composed of a roller 69E into which the support shaft 12 of the development unit 65 is inserted and a feed roller 69A disposed on the upper component 20 side with respect to the roller 69B. The feed roller 69A is rotated by a drive motor (not shown) at the same circumferential speed as that of tie photoconductive drum 61.

With the aforesaid arrangement of the recording unit 60 and upper component 20, a recording paper feed path is formed between the upper surface of the recording unit 60 (tile upper surface of the toner cartridge 65C) and the lower surface of the upper component 20 (the upper recording paper guide plate 21E and recording paper feed path regulation plate 21F). Recording paper accommodated in the recording paper cassette 40 mounted to the cassette mounting unit 31 of the paper feed unit 30 is fed ,llrol1gll tllc recording paper path along a feed path shown by the dot-dash-line in Figure 1, and received information is printed on the lower surface of each of the recording papers by the recording unit 60.More specifically, the recording paper accommodated in the recording paper cassette 40 is sequentially introduced into tiie recording paper path from the uppermost one thereof by the rotation of the recording paper introduction roller 33 of the cassette mounting unit 31, while the surface of the photoconductive drum 61 is main-scanned (exposed) in the rotational axis direction thereof with a laser beam modulated by received etiaracters or image information and emitted from the scanning optical unit 64. At the same time, the photoconductive drum 61 is rotated (sub-scanned), and the development unit 65 develops a latent image formed on the surface of the photoconductive drum 61 and forms a toner image.The toner image is transferred onto the recording paper fed by the pair of drive rollers 69 at a speed in synchronism with the circumferential speed of the photoconductive drum 61 and charged by the transfer charger 66, and then the toner image is fixed onto the recording paper by the fixing unit 67.

The recording paper is then discharged through the front end of the apparatus.

Next, ttle development unit 65 provided with a scraper 70 as a scraper structure embodying the present invention will be described in . detail.

Figure 2 is a perspective view of the development unit 65 viewed from a back side from which the toner cartridge 65c is removed and shows the inside of a toner accommodation unit 65D viewed tllrough an opening 65E to which toner is supplied from the toner cartridge 65c.

Tlle development unit 65 is arranged such that the toner accommodation unit 65D is formed in the vessel 65t of the development unit with the upper portion thereof opened as the toner supply opening 65E. A toner supply opening 65F for supplying toner to the development roller is open along one of the longitudinal wall surfaces of the toner accommodation unit 65D, and the development roller is disposed behind tije toner supply port 6SF, although it cannot be seen at the angle of Figure 2.

Although not shown in Figure 2, the toner cartridge is detachably mounted to the toner supply opening 65E and toner is supplied from the toner cartridge 65C into the toner accommodation unit 65D.

The development roller is rotatably supported at tilC opposite tc ends thereof by side walls 65G, 65G of the vessel 65A constltutlng the toncr accommodation unit 65D. A gear 81 fixed to a shaft 80 projecting outside of one of the side walls 65G is meshed with a gear train 82 disposed outwardly of the side wall 65G, and thus the development roller is rotated at a predetermined speed by a rotating force transmitted through the gear train 82.

Tiie scraper 70 is contained in the toner accommodation unit 65D along the longitudinal direction thereof.

As shown in the exploded perspective view of Figure 3, the scraper 70 is composed of a plurality of unit blocks 70A connected in series by sijafts 71 thereof into which a drive shaft 70B is inserted.

Each of the unit blocks 70A is arranged such that arms 72, 73 thereof each having a predetermined thickness extend in the right and left directions (substantially in the radial direction of the shaft 71) such that the outside surfaces of the arms 72 and 73 form planes in contact with the outside peripheries of the shaft 71 located at diametrically opposite positions thereof. The extreme ends of the arms 72 and 73 are slightly bent in the direction opposite to the rotational direction of the scraper 70 shown by the arrow in Figure 3, and the right and left extreme ends of both arms 72, 73 are connected by blades 74, 74. More specifically, the blades 74, 74 are formed along a plane having a predetermined angle to the center line of the shaft 71 and intersecting the center line substantially at the center in the longitudinal direction thereof.

A slit 71A as an engaging portion having a predetermined width is defined in an end of the shaft 71 in the diametrical direction thereof and an engaging projection 71B as an engaging portion having a width and length capable of engaging with the slit 71A projects from the other end of the shaft 71 perpendicularly to the slit 71A (i.e., rotated by 900 with respect to the slit 71A).

The plurality of unit blocks 70t formed as described above constitute the single scraper 70 in such an arrangement that the drive shaft 70B is inserted into the shafts 71 of the unit blocks 70A. The engaging projection 718 at one end of each unit block 70A is engaged with the slit 71A of the adjacent unit block 70A and thus the unit blocks 70A are integrally coupled so that they are not relatively rotated with the phases of the blades 74 of the unit blocks adjacent to each other displaced by 900.

Further, as shown in Figure 3, the unit block 70A located at the extreme end is prevented from being relatively rotated with respect to the drive shaft 70B by a pin 70C driven into the drive shaft 70B exposed from the engaging projection 71B or slit 71A and thus this unit block 70A is rotated by the rotation of the drive shaft 7013.

The drive shaft 70B is rotatably supported by the side walls 65G, 65G on the opposite sides of the housing 10 and a gear 70D fixed to the portion of the drive shaft 70B projecting outside of one of the side walls 65G is meshed with the same gear train 82 as that used for rotating the aforesaid development roller, Ihus the drive shaft 70B is rotated at a predetermined speed by a rotating force transmitted through the gear train 82.

Note that tiie bottom portion of the toner accommodation unit 65D is formed in an arc shape following tiie rotational locus adjacent to the extreme end of the blade 74 of the scraper 70-.

Then, the scraper 70 arranged as described above is rotated by the rotation of the drive shaft 70B rotated by a drive source (not shown) through the gear train 82 and scrapes toner in the toner accommodation unit G5D by using tlie blades 74 thereof to supply it from the toner supply opening 65F to tlie developing roller as well as prevents the toner from being solidified and pelletized.

As described above, the blade 74 of each unit block 70A is formed obliquely with respect to the center line of the shaft 71, whereby the toner scraped by tlle blade 74 is moved toward the oblique side direction along the blade 74 instead of being moved in the radial direction of the rotation shaft 71.

Furthermore, the direction in which the toner is moved is reversed depending upon the symmetrically disposed blades 74, 74 even if these blades are provided with the same unit block 70A. More specifically, as shown by the arrows in Figure 5 showing the state of the scraper 70 rotated from the state shown in Figure 4 by 900, the toner located at a position corresponding to a specific unit block 70A is moved in one direction by one of the blades 74 of the unit block 70A and when the unit block 70A is rotated by a half revolution (1800), the toner is moved in the opposite direction by the other of the blades 74 and thus the toner is slightly and alternately moved in the right and left directions.

With this arrangement, when the toner is unevenly distributed in the longitudinal direction of the toner accommodation unit 65, the toner is slightly moved from ic portion where a larger amount of it located to the portion where a smaller amount of it is located, Thus, an uneven distribution of the toner in the longitudinal direction of the toner accommodation unit 65D can be solved.

Note, although the indlvidually formed unit blocks 70A are coupled in series to form the scraper 70 in the above embodiment, the scraper may be integrally formed and further tiie configuration of the blade may be suitably changed.

Further, altiiougij the scraper structure for the development unit of the present invention is applied to the development unit for the electrophotographic facsimile apparatus in the aforesaid ernbodiment, the present invention is not limited thereto and the scraper structure may be of course applied to a development unit for a copier machine and the like.

Claims (13)

1. A scraper structure for a toner accommodation vessel for a development device including a development roller, such that the scraper structure in use extends substantially parallel to the development roller for supplying toner in said toner accommodation vessel to the development roller upon rotation of the scraper structure, said scraper structure comprising: a shaft extending in use substantially parallel to the development roller; and a plurality of blades, each of which is supported substantially symmetrically relative to the central axis of said shaft and extends substantially in a plane inclined relative to said central axis and intersecting said central axis substantially at the centre thereof in the longitudinal direction of said blade; wherein said blades are disposed in series in the axial direction of said shaft and the angular phases of adjacent blades differ.

2. A scraper structure according to claim 1, wherein the angular phases of adjacent blades differ by a predetermined angle.

3. A scraper structure according to claim 2, wherein the angular phases of adjacent blades differ by substantially 900.

4. A scraper structure according to any one of the preceding claims, wherein each said blade comprises a pair of blade members supported relative to said shaft.

5. A scraper structure according to claim 4, wherein a portion of said shaft and each said pair of blade members fixed to the portion of said shaft constitute a unit block, and a plurality of unit blocks are connected in series so as to align the central axes of the portions of the shaft in a single line.

6. A scraper structure according to claim 4, wherein each said blade member has a predetermined width and is supported by a respective portion of said shaft through arms at the opposite ends in the axial direction of said portion of said shaft and formed to a frame shape with an opening defined at the central portion thereof.

7. A scraper structure according to claim 6, wherein each said portion of said shaft includes engaging portions at the opposite ends in the longitudinal direction thereof for engaging with engaging portions of other portions of said shaft.

8. A scraper structure according to any one of the preceding claims, wherein said shaft has a through hole defined at the center in the axial direction thereof through which a drive shaft is inserted in use.

9. A scraper structure according to claims 7 and 8, wherein said through hole of the shaft has a substantially circular cross section, and said drive shaft is inserted into the shaft and an engaging portion of each said portion of said shaft is engaged with the engaging portion of the adjacent unit block so that both the unit blocks can be integrally rotated with each other.

10. A scraper structure according to claim 9, wherein the engaging portions of each said portion of said shaft comprise an engaging projection at one end and an engaging groove at the other end.

11. A scraper structure according to claim 8, wherein at least one said engaging portion located at an outermost position is engaged in use with an engaging member fixed to said drive shaft and each said unit block is relatively unrotationally coupled with said drive shaft.

12. A scraper structure for a toner accommodation vessel for a development device including a development roller, such that the scraper structure in use extends substantially parallel to the development roller for supplying toner in said toner accommodation vessel to the development roller upon rotation of the scraper structure, said scraper structure substantially as herein described with reference to the accompanying drawings.

13. An electrophotographic reproduction apparatus including a scraper structure according to any one of the preceding claims.