US 3700142 A
A powder dispensing unit suitable for use as a copier developer unit for developing a latent image with a dry toner powder. A magnetic roller and an auger are rotatably mounted in a housing: the roller having a power takeoff gear at one end and a power transfer gear and a camming disc at the other; the auger having an end-mounted driven gear mated with the power transfer gear. An end portion of the auger is mounted in a feed block having an upwardly extending chute aperture permitting toner feed upwardly toward an inlet portion of a toner distributor unit, which is reciprocably mounted in the housing. A rocker arm having a roller at each end-one contacting an undulating surface of the camming disc, the other contacting a camming post-reciprocates the toner distributor unit laterally in the housing. The toner distributor unit has a sloping, slotted distributor channel and a pair of sloping surfaces for gravity feeding toner powder therealong, and a trimming member to remove toner from the roller for admixture with toner fed along the distributor channel from the inlet.
Description (OCR text may contain errors)
United States Patent Waibel  POWDER DISPENSING UNIT 72 inventor: Helmut K. Waibel, San Leandro,
[73 Assignee: The Singer Company, New York,
 Filed: Sept. 20, 1971 [211 Appl. No.: 181,988
 U.S. Cl. ..222/l09, 222/162, 222/200, 222/233, 222/414, 118/637  int. Cl. ..B67d 1/16  Field of Search ..2 22/31,8,'108, 109, 424, 162,.
222/233, DIG. 1, 414, 200, 234,160,161, 199, 196; 118/637, 258
[451 Oct. 24, 1972 Primary Examiner-Robert B. Reeves Assistant Examiner-James M. Slattery Attorney-Warren P. Kujawa et al.
57 ABSTRACT A powder dispensing unit suitable for use as a copier developer unit for developing a latent image with a dry toner powder. A magnetic roller and an auger are rotatably mounted in a housing: the roller having a power takeoff gear at one end and a power transfer gear and a camming disc at the other; the auger having an end-mounted driven gear mated with the power transfer gear. An end portion of the auger is mounted in a feed block having an upwardly extending chute aperture permitting toner feed upwardly toward an inlet portion of a toner distributor unit, which is reciprocably. mounted in the housing. A rocker arm having a roller at each endone contacting an undulating surface of the camming disc, the other contacting a cammingpost-reciprocates the toner distributor unit laterally in the housing. The toner distributor unit has a sloping, slotted distributor channel and a pair of sloping surfaces for gravity feeding toner powder therealong, and a trimming member to remove toner from the roller for admixture with toner fed along the distributor channel from the inlet.
11 Claims, 9. Drawing Figures PATENTEDHBI 24 m2 3.700.142
SHEET 2 OF 4 FIG-8 P'A'TE'N'TEnucm 1912 3.700. 142
SHEET 3 OF 4 POWDER DISPENSING UNIT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to devices for applying a powdered substance to the surface of a moving member, such as a moving sheet, and more particularly to apparatus for developing a latent image on a sheet-like surface with a developer powder.
2. Description of the Prior Art Devices are known for applying a powdered substance to the surface of a moving, sheet-like member. In U.S. Pat. No. 3,088,386, e.g., a developer unit is disclosed typical of those which utilize the well-known magnetic brush principle for applying triboelectric powdered toner developer particles to the surface of a copy sheet carrying a latent image in order to render the image visible. In the past, such developer units have employed two or more augers to mix and distribute the toner powder in a uniform manner across the working width of the magnetic roller. Because of the high surface friction of the toner powder, however, and due to the fact that the toner is augered in opposite directions simultaneously, excessive mechanical power has been required to drive the augers and the roller.
In powder dispensing devices of the above type, as well as in other similar devices, it has been found that the thoroughness and uniformity with which the developer powder is distributed along the working width of the roller is critically related to the total volume of powder contained in the unit. As the total volume of powder is depleted by adherence to the surface of the developed sheet, and also by spillage outside the housing of the device, it has been observed that the efficiency of the augers rapidly diminishes.
A problem related to the above-noted decrease in efficiency of the augers is that of powder spillage outside the housing of known powder dispensing devices. Because of the constraints inherent in the mechanical design on the relative placement of the roller and the augers within the housing of such devices, powder may easily escape from the brush surface and fall outside the dispensing unit. This escaping powder has been found to contaminate other elements in the machine with which the dispensing device is associated-cg. the rollers and corona charging units of an electrostatic copier-and to increase the frequency with which the powder must be replenished. These and other undesirable results produced by powder spillage increase the amount of down time of the associated machine and also increase the total cost of operating the device.
SUMMARY OF THE INVENTION The invention comprises a powder dispensing apparatus which employs a single auger in association with a powder dispensing roller and a reciprocating powder distributor unit. In a preferred embodiment designed for use in an electrostatic copier employing dry triboelectric toner, the roller comprises a magnetic roller for forming a toner brush. This roller is rotatably disposed in a housing with a power takeoff gear secured to one end, and a power transfer gear and a means for providing oscillatory motion secured to the other end. The power transfer gear mates with a driven gear secured to one end of an auger rotatably disposed generally parallel with the roller axis. The means for providing oscillatory motion drives one end of a rocker arm, the other end of which provides reciprocating motion for reciprocating the powder distributor unit laterally of the housing in cooperation with a compression spring. An end portion of the auger is surrounded by a feed block having an upwardly extending chute aperture permitting toner feed upwardly toward an inlet portion of the toner distributor unit. The toner distributor unit has a sloping, shotted distributor channel connected to the toner inlet for sprinkling powder toner onto a first, rearwardly sloping surface. A trimming member is also included for removing toner from the roller for admixture with the toner sprinkled onto the first surface. A second surface, which slopes downwardly and forwardly toward the roller, is provided for gravity feeding the admixed toner toward the roller. A doctor member is provided for trimming excess toner from the roller. I
In an alternate embodiment, the distributor channel is divided into a first portion for distributing toner onto a first portion of the first surface and a second portion for distributing toner onto a second portion of the first surface, and an adjustable gate is provided for varying the amount of toner introduced into the first and second portions. This embodiment permits lateral re gulation of the toner brush density.
Powder dispensing devices constructed according to the invention have been found to require significantly less mechanical power to operate than known twin auger devices. In addition, as will be evident from the description of the preferred embodiments set forth below, the invention significantly reduces the problem of powder spillage. It has been further discovered that the performance of devices constructed according to the invention is relatively unaffected by the depletion of the powder contained therein.
For a fuller understanding of the nature and advantages of the invention, reference should be had to the following detailed description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a preferred embodiment of the invention;
FIG. 2 is a front elevation of the device of FIG. 1;
FIGS. 3 and 4 are elevations of the left and right ends respectively of the device of FIG. 1;
FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 4 showing details of the auger and the feed block of the FIG. 1 device;
FIG. 6 is a sectional view taken along line 6-6 of FIG. 1 showing details of the auger, feed block, roller and toner inlet of the FIG. 1 device;
FIG. 7 is a sectional view taken along lines 77 of FIG. 1 illustrating the operation of the device;
DESCRIPTIONOF THE PREFERRED EMBODIMENTS Turning now to the drawings, FIGS. 18 show a preferred embodiment of the invention designed for use as a copier developer unit in an electrostatic copier of the type disclosed in 1.1.8. Pat. No. 3,591,846 issued July 6, 1971. In copiers of this type, a latent electrostatic image on a photoconductive surface of a web is rendered visible by brushing the imaged surface with a dry, triboelectric toner powder. This brushing step is performed by utilizing the magnetic brush principle, whereby toner powder having a magnetic component is releasably adhered to the surface of a magnetic roller by the force of magnetic attraction between the magnetic component and the roller, thereby forming a magnetic brush, the bristles of which comprise the toner powder. The preferred embodiment to be described comprises an apparatus for carrying out this developing process.
A dispensing roller having an axial shaft 11 is rotatably mounted in a pair of stationary side walls 12, 14 by any suitable means, preferably bearings such as bearing 13 illustrated for the right end of roller 10 in FIG. 5. In the preferred embodiment, roller 10 is a magnetic roller of the type disclosed in US. Pat. application Ser. No. 21,609 now US. Pat. No. 3,628,504 for Adjustable Mounting Device for Electrostatic Copier Developer Magazine filed Mar. 23, 1970, and has a main working surface 15 and an auxiliary working surface 16 separated by a groove 17. A power takeoff gear 111 is secured to one end of roller 10 which is adapted to be driven by a suitable source of mechanical power (not shown). Secured to the other end of roller 10 is a driving gear 19 and a camming disc 20, both for purposes described below.
A powder conveying auger 22 is rotatably secured by any suitable means, preferably bearings such as bearing 23 illustrated in FIG. 5, to side walls 12, 14 forwardly of and below roller 10 (see FIG. 7). Secured to an end of auger 22 is a driven gear 23 enmeshed with driving gear 19. As best seen in FIGS. 1, 5, and 6, a portion of the driven end of auger 22 is rotatably received in a feed block 24 having a central cavity 25 opening in a generally upward direction. Feed block 24 is secured to a forward wall portion 26 of a housing member 27 by any suitable means, e.g. screws 211. The extreme righthand feed portion of auger 22 terminates in a chamfered disc 29.
A rocker arm 30 is pivotally secured by means of a pin 31 to a post 32 extending laterally from side wall 14. The ends of rocker arm 30 are provided with camming rollers 33, 33' rotatably mounted on pins 34, 34' respectively. Rocker arm 30 is dimensioned and positioned so that camming roller 33 rides along the undulating surface of camming disc 20. While the shape of the surface of camming disc 20 may vary according to a given application, in the preferred embodiment excellent results have been obtained with a six slope harmonic surface providing a lateral displacement of 0.070 inch.
Reciprocably mounted in the housing comprising side walls 12, 14 and housing member 27 is a toner distributor unit generally indicated at 10. Toner distributor unit has a top cover plate 42, shown for the sake of clarity in FIG. 1 as constructed from a transparent material, secured to a pair of side walls 4 1, 16 by means of screws 47. A toner distributor channel 19 is secured to the underside of cover plate 42 by means of fasteners 50 and extends generally diagonally of cover plate 42. Toner distributor channel 19 is a generally U-shaped member provided with a plurality of spaced overlapping slots 52 and is shaped and mounted to provide a toner support surface 63 which slopes downwardly toward the left-end portion thereof as viewed in FIGS. 1 and 2. The extreme right-end portion of toner distributor channel 49 is formed to provide a forwardly extending, broadened toner inlet portion 54 having a beveled front edge 55. As most clearly shown in FIG. 6, toner inlet portion 5 1 is angled slightly downward toward the rear of the unit and arranged so that the bottom surface thereof is positioned closely adjacent the surface of auxiliary portion 16 of roller 10.
Secured between side walls 14, 46 of toner distribu' tor unit 40 below cover plate 12 and distributor channel 49 is a first plate 60 which slopes downwardly toward a rear wall 61 of toner dispenser unit 40 (see FIGS. 1 and 7). The rear edge of plate 60 is cutaway to form a number of apertures 6 1, 65 providing communication with the space therebelow continuously across the entire working width of the main working surface 15 of roller 10. In the preferred embodiment, the rear edge of plate 60 is supported in a slot 66 in rear wall 61.
Secured between side walls 1 1, 16 of toner distributor unit 40 below first plate 60 is a second plate 68 which slopes downwardly toward the front of the unit, terminating adjacent roller 10.
A trimming member 70 having an outer arcuate surface 71 and an inner arcuate surface 72, the latter being generally concentric with the surface of roller 10, is secured to the forward edge of first plate 60. Arcuate surfaces 71, 72 are joined to form a forward edge 73 for removing toner from the surface of roller 10 in the manner described below.
Toner distributor unit 40 is reciprocably supported by a pair of rear support pins 74, 74 and a pair of front support pins 75, 75 secured to side walls 4 1, 46. Rear support pins 741, 74' are slidably received by slightly oversize apertures 76, 76 formed in side walls 12, 14, respectively. Front support pins 75, 75' are slidably received by slightly oversize bushings 77, 77 fitted into appropriate openings in side walls 12, 1 1, respectively. A post 60 having a pedestal 81 is secured to side wall 46 of toner distributor unit 10. Post 80 extends laterally through an aperture 03 in side wall 14, the face of pedestal 81 being adapted to contact the outer surface of camming roller 33.
A cup 85 having a collar 86 is received in an aperture 87 in side wall 12. As best shown in FIG. 11, cup 85 has a spring 88 received in an axial bore, one end 90 of which abuts an inner end wall 91 of cup 35. The other end 92 of spring 88 abuts the outer surface of side wall 44. In an assembled device, spring 88 biases toner distributor unit 40 to the right (as viewed in FIG. 1) so that the face of pedestal 81 contacts the surface of camming roller 33.
As best seen in FIGS. 1 and 7, a doctor rod 95 is mounted adjacent and generally parallel to roller 10 by means of screws 96 for trimming excess toner from the surface of roller 10 in the manner described below.
Mounted on the forward portion of side wall 44 by means of screws 97 is a hopper 96 for channeling fresh toner from an external supply source (not shown) TO auger 22.
The operation of the preferred embodiment proceeds as follows. Rotation of power takeoff gear 18 causes rotation of roller and auger 22 through enmeshed gears 19, 23. As camming disc 20 rotates with roller 10, the camming action of the undulating surface of disc 20 on rocker arm 30, in cooperation with the return bias provided by compression spring 88, causes toner distributor unit 40 to reciprocate between side walls 12, 14. When toner developer powder having a magnetic component is introduced into hopper 98, it is channeled down onto auger 22 and conveyed thereby into central cavity 25. Once inside cavity 25, the toner is forced upwardly by disc 29 and the walls of cavity 25. Because of the magnetic attraction between the toner and auxiliary working surface 16 of magnetic roller 10, the toner is then raised by surface 16, pared therefrom by reciprocating front edge 55 and deposited at the inlet portion 54 of toner distributor channel 49. Toner thus deposited is urged rearwardly along toner distributor channel 49 by the combined action of subsequently deposited toner which forces previously deposited toner toward the rear of the unit, and the force of gravity on the toner assisted by the reciprocating movement of inlet portion 54 and channel 49. As the toner progresses along support surface 53, it cascades through slots 52 onto the top surface of reciprocating first plate 60, flows gently under the influence of gravity and the reciprocating motion of plate 60 toward the rear, and cascades through apertures 64, 65 onto the top surface of reciprocating second plate 68. Due to the forward slope of plate 68, the toner flows gently therealong under the influence of gravity and the reciprocating motion of plate 68 toward magnetic roller 10. As the toner reaches main working surface of roller 10, it is magnetically attracted thereto to form a magnetic brush of toner particles. Doctor rod 96 trims off excess particles as the brush rotates therepast, which particles cascade down onto auger 22 and are subsequently recycled. After the toner particles have been swept past the associated surface to be developed, described below, they are pared from the surface 15 of roller 10 by reciprocating trimming edge 73, and conveyed rearwardly along outer arcuate surface 71 and the top surface of reciprocating first plate 60, where they encounter more toner cascaded from above through slots 52.
F IGS. 6 and 7 illustrate the operation of the preferred embodiment when filled with a working quantity of toner developer powder 100. In these figures, element 102 represents a flexible web having a photoconductive surface of the type disclosed in the above-noted US. Pat. No. 3,591,846. Web 102 is threaded over a number of rollers 103-105 and drawn past the working portion of the main working surface 15 of roller 10 in the direction indicated by the arrows, with the latent image bearing surface of web 102 facing roller 10. The preferred embodiment is positioned with relation to web 102 by means of mounting apertures 107, 108 and suitable mounting members (not shown) so that the toner particles carried by the outer surface of roller 10 brush the latent image bearing surface of web 102 as roller 10 rotates in the direction shown. It is important to note that, due to the geometry of the copier developer unit, any toner particles which may be removed from the surface of roller 10 but which may fail to adhere to web 102 fall back into the unit, e.g. onto roller 10 or onto auger 22, and not outside the unit. This feature prevents any depletion of toner 100 by spillage outside the unit and provides the additional beneficial effects noted above.
As will now be evident, with a working quantity of toner developer powder 100 in the copier developer unit, an endless stream of powder 100 is lifted by auxiliary surface 16 of roller 10, pared by knife edge 55, conveyed along toner inlet portion 54 and distributor channel 49, and cascaded onto first plate 60,.there to mix with other toner trimmed from main working surface 15 of roller 10 by trimming edge 73 and conveyed rearwardly along outer arcuate surface 71. The mixed toner is continuously conveyed along first plate 60, cascaded onto second plate 68 and conveyed therealong to roller 10. As the conveyed toner encounters main working surface 15 of roller 10, it is attracted thereto, thereby forming the magnetic brush, which is then trimmed by doctor rod 95 and used to develop the image on web 102. Excess toner which fails to adhere tosurface 15 falls into a reservoir trough 109 formed by the forward inner portion of housing member 27. After passing the web 102 surface, the brush surface encounters trimming edge 73, toner powder is trimmed from main working surface 15 and conveyed rearwardly along outer arcuate surface 71 and first plate 60 to mix with other toner cascaded from above and to recycle in the above manner.
Toner trimmed by doctor rod 95 cascades onto auger 22 and is conveyed toward central cavity 25 along with the excess toner in trough portion 109. Once having reached central cavity 25, this toner is forced upwardly by disc 29 and the walls of cavity 25, raised by auxiliary surface 16 of roller 10, pared from surface 16 by knife edge and deposited in inlet portion 54. The thusdeposited toner is conveyed along toner distributor channel 49 and cascaded onto first plate to mix with other toner as noted above.
It is noted that in operation, toner which has been used, i.e. toner which has had the nonmagnetic component thereof depleted by virtue of being transferred to the surface of web 102 while the magnetic component remains behind on surface 15 of roller 10, is continuously mixed on first plate 60 with fresh toner from toner distributor channel 49. Because of this continuous intermixture of used and fresh toner, the composition of the toner presented to roller 10 at the forward edge of second plate 68 is extremely uniform throughout the operation of the device, which results in extremely uniform toner density along the width of main working surface 15 and correspondingly uniform lateral development of the latent images on web 102.
The above-described copier developer unit has been found to provide substantially uniform results over a wide range of volume of toner powder. Stated otherwise, beginning with a quantity of toner powder which fills trough portion 109, no noticeable deterioration in the thoroughness with which the toner is intermixed and in the lateral uniformity of the magnetic brush has been observed until nearly all toner has been depleted. Since the unit operates in a uniform manner over a wide range of toner volume, intricate and expensive mechanisms required by prior art devices to replenish the amount of toner therein by metering precise quantities of toner from an external reservoir to an inlet need not be employed with the preferred embodiment.
7 Moreover, good results have been obtained by merely replenishing the supply of toner on an interrupted basis, e.g. by periodically inserting fresh toner into hopper 98.
As noted above, in the preferred embodiment, camming disc 21) is provided with a six slope harmonic surface providing a lateral displacement for toner distributor unit 40 of 0.070 inch. Optimum results have been obtained with several toner development powder compositions by rotating roller 11) and camrning disc 21) at an angular speed which will reciprocate toner distributor unit 411 at a frequency of 16 cycles per second. It is understood that the optimum rotational speed of roller 111 and camming disc 20, and the optimum frequency of reciprocation of toner distributor 411, will vary with the relative sizes of the various elements, the shape of the surface of camming disc 21), and the type of powder employed in the unit. These parameters may most readily be determined for any given case in an empirical manner.
FIG. 9 illustrates an alternate embodiment of toner distributor channel 49 which provides lateral regulation of the magnetic brush density. Toner distributor channel 110 of FIG. 9 is provided with a pair of outer upstanding walls 112, 114 and a central upstanding wall 115 which partitions the toner support surface of channel 110 into a first distributor channel portion 118 and a second distributor channel portion 119. First distributor channel portion 118 is provided with a first plurality of overlapping slots 121, while second distributor channel portion 119 is provided with a second plurality of overlapping slots 122, both for the same purpose as slots 52 of toner distributor channel 49. Pivotally mounted in an inlet portion 125 adjacent a beveled edge 126 is a movable gate 127 for regulating the flow of toner developer powder into channel portions 118, 119. A link arm 128 is secured at one end to gate 127. The other end of link arm 128 is engaged by the proximal end of a control arm 131), the distal end of which (not shown) is accessible to a machine operator. By regulating the position of gate 127 through the manipulation of control arm 1311, the relative amounts of toner developer powder flowing into channel portions 118 and 119 may be varied from a first extreme position shown in phantom, wherein no toner flows to channel portion 118, to a second extreme position also shown in phantom, wherein no toner flows into channel portion 119. As will be apparent to those skilled in the art, in the first extreme position all toner will flow along channel portion 119 and cascade down onto the left surface portion only of first plate 611. If the unit is operated in this condition, only the left half of the main working surface 15 of roller will be supplied with fresh toner. Consequently, only one-half of the image surface of web 1112 will be developed. Similarly, if the unit is operated with gate 127 in the second extreme position only the right half of the main working surface of roller 10 will be supplied with fresh toner and only the other half of the image surface of web 162 will be developed. Operation of the unit with gate 127 in the intermediate position illustrated results in normal image development, while other positions of gate 127 provide variable asymmetric image development, as desired. As will now be evident, toner distributor channel 111) thus provides a simple means for controlling 8 the lateral density of the magnetic brush and consequently the lateral image density.
While the foregoing provides a full disclosure of the preferred embodiments of the invention, it is un- 5 derstood that various modifications, alternate constructions, and equivalents may be employed without departing from the true spirit and scope of the invention. For example, although the preferred embodiment has been described with reference to the field of electrostatic copiers, other fields of use for the invention will occur to those skilled in the art. Such uses may contemplate the utilization of a magnetic roller with developer powder having a magnetic component, or other types of rollers with developer powders which are releasably adherent thereto. Therefore, the above description and illustrations should not be construed as limiting the scope of the invention which is solely defined by the appended claims.
What is claimed is:
l. A powder dispensing unit for distributing powder along a work surface comprising:
a roller rotatably mounted in said housing for axial rotation, said roller having a surface for releasably adhering said powder thereto, said surface having a main working portion and an auxiliary working portion;
a powder distributing unit reciprocably mounted ad jacent said roller for distributing said powder along said main working portion, said distributing unit having an inlet portion adjacent said auxiliary working surface for removing powder therefrom; and
means for feeding said powder from the vicinity of said roller toward said inlet portion.
2. The apparatus of claim 1 wherein said roller in cludes a first driven gear for providing power transfer from an associated power source, a second gear for driving said powder feeding means, and means for providing oscillatory motion for driving said distributing unit.
3. The apparatus of claim 2 wherein said oscillatory motion means comprises a camming disc having an undulating surface.
4. The apparatus of claim 1 wherein said powder distributing unit comprises a first powder distributing surface inclined downwardly and rearwardly of said roller; a second powder distributing surface positioned below said first surface and inclined downwardly toward the front of said unit, said first and second surfaces converging at the rear of said powder distributing unit;
a trimming member located between said roller and said first surface for removing portions of said powder from said roller;
a slotted distributor channel disposed generally diagonally of said first surface an inclined to pro vide powder movement therealong, said powder inlet being coupled to said channel; and
means for slidably mounting said surfaces, said trimming member and said channel in said housmg;
65 and further including means for reciprocating said powder distributing unit in said housing.
5. The apparatus of claim 1 wherein said reciprocating means comprises a camming post extending from said powder distributing unit and secured thereto, means coupled to said roller for providing oscillatory motion, a rocker arm having a first end coupled to said oscillatory motion means and a second end coupled to said camming post, and a means for biasing said distributing unit to a rest position.
6. The apparatus of claim wherein said first and second ends of said rocker arm are each provided with a camming roller.
7. The apparatus of claim 5 wherein said biasing means comprises a means secured to said housing having a tension member coupled to said powder distributing unit.
8. The apparatus of claim 4 wherein said distributor channel includes a first channel portion for distributing said powder onto a first portion of said first surface, a second channel portion for distributing said powder onto a second portion of said first surface and an adjustable gate for varying the amount of said powder introduced into said first and said second channel portions.
9. The apparatus of claim 1 wherein said powder feeding means comprises an auger rotatably disposed substantially parallel with said roller, and a feed block mounted adjacent said powder inlet and surrounding a portion of said auger, said feed block having an upwardly extending chute opening for permitting upward movement of said powder, said portion of said auger having a disc member for assisting upward movement of said powder.
10. The apparatus of claim 1 further including doctor member for trimming excess powder from said roller.
11. The apparatus of claim 1 wherein said powder comprises a developer toner having a magnetic component and said roller comprises a magnetic roller for forming a toner brush therewith.