US3692403A

US3692403A - Automatic control of toner concentrations

Info

Publication number: US3692403A
Application number: US211380A
Authority: US
Inventors: Lyman H Turner
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1971-12-23
Filing date: 1971-12-23
Publication date: 1972-09-19
Anticipated expiration: 1989-09-19
Also published as: JPS4874236A; DE2252641A1; NL7216953A; CA979635A; DE2252641B2; DE2252641C3; JPS543736B2; GB1409578A

Abstract

Controls for manually selecting toner concentrations in a xerographic imaging system are overridden to prevent overtoning. A drive mechanism responsive to copy production incrementally resets the toner controls to a standard toner concentration when that level is exceeded.

Description

United States Patent Turner [4 1 Sept. 19, 1972 AUTOMATIC CONTROL OF TONER CONCENTRATIONS Lyman H. Turner, Pittsford, NY.

Stamford,

Inventor:

Xerox Conn.

Filed: Dec. 23, 1971 Appl. No.: 211,380

Assignee: Corporation,

Us. 01. ..3ss/3, 1 17/175, 118/637, 222/199 Int Cl. ..G03g 15/08 Field ofSearch....355/3; 118/637; 117/16, 17.5;

[56] References Cited UNITED STATES PATENTS 3,348,522 10/1967 Donohue ..1l8/637 X 3,348,523 10/1967 Davidson et a1. ..1 18/637 X 3,376,854 4/1968 Kamola ..1 17/ 17.5 X

Primary Examiner-Robert P. Greiner Attorney-James J. Ralabate et a1.

[57] ABSTRACT Controls for manually selecting toner concentrations in a xerographic imaging system are overridden to prevent overtoning. A drive mechanism responsive to copy production incrementally resets the toner controls to a standard toner concentration when that level is exceeded.

17 Claims, 6 Drawing Figures PATENT EDSEP 19 m2 SHEET 1 [IF 4 PATENTED SE? 19 I972 SHEET 2 [IF 4 AUTOMATIC CONTROL OF TONER CONCENTRATIONS BACKGROUND OF THE INVENTION This invention relates to the dispensing of xero' graphic toner particles. More specifically, this invention relates to novel methods and apparatus for limiting the dispensing rate of a powder from a hopper having a reciprocating dispensing gate.

Reciprocating gate dispensing apparatus is disclosed in U.S. Pat. No. 3,013,703 to Hunt, the disclosure of which is incorporated herein by reference. The dispensing apparatus includes a hopper for holding a powder, e.g., xerographic toner particles, with a dispensing plate slightly spaced from an orifice in the bottom of the hopper. In the space is located a reciprocating device or metering element that controls the flow of powder through the gaps or gate formed between the hopper orifice and the dispensing plate. The flow rate of powder is controllable by changing the length of travel of the reciprocating device and the reciprocating frequency, the number of cycles per unit time the device is reciprocated.

In many xerographic machines it is the practice to tie the reciprocating frequency to the rate of toner image production to add toner to a xerographic development system at a rate related to toner consumption. Thereafter, the quantity of powder being dispensed can be scaled up or down by increasing the length over which the reciprocating device travels. This scaling operation is commonly performed by an operator action such as pushing a button or moving a handle to one ofa plurality of toner settings.

A problem can arise in the foregoing xerographic systems if the operator fails to properly scale the toner concentration levels to suit the copying requirement of the machine. When a different type of copy is desired, e.g., when a machine making line copies is used to produce copy having solid area coverage, the operator temporarily scales the toner concentration for that particular task. Should the operator fail to return the concentration to the line copy level, it is reasonable to expect trouble somewhere in the system due to excess toner quantities.

Accordingly, it is a primary object of this invention to devise methods and apparatus for automatically changing toner concentrations in xerographic systems.

More specifically, it is an object of the invention to change automatically toner concentration in a xerographic system over a finite number of copy forming cycles.

It is also an object of the present invention to eliminate human errors in determining toner concentrations for xerographic copying systems.

Another object of the present invention is to regulate the length of travel of the reciprocating device in a powder dispenser of the type disclosed in the Hunt Patent.

Yet a further object of this invention is to devise a drive mechanism capable of imparting incremental angular displacements totaling less than 360 of rotation to a drive member in response to multiple 360 rotations of a driving member. This object is, of course, directed to the solution of the other objects.

These and other objects of the instant invention are realized by coupling a drive mechanism to the operator control device for scaling powder concentrations. The drive mechanism in question is responsive to the number of copies produced, or other production criteria, and acts on the operator control device. In the specific xerographic embodiment disclosed herein, the drive mechanism automatically resets by incremental amounts during the production of a fixed number of copies an operator control handle to a standard position when the toner concentration level represented by the standard position is exceeded. Undertoning, i.e., toner concentrations associated with a handle setting below the standard level, does not harm the system and is usually readily detected in the quality of the copy. On the other hand, overtoning, i.e., too great toner concentrations, may not affect copy quality directly and go undetected until a system failure occurs.

DESCRIPTION OF THE DRAWINGS Other objects and features of the present invention will be apparent from the present description and from the drawings which are:

FIG. 1 is a side elevation, partly in section of a xerographic system using a reciprocating gate toner dispenser having an operator actuated handle for scaling toner concentrations.

FIG. 2 is a view of a reciprocating gate powder dispenser, an operator controlled handle for varying the length of travel of the reciprocating device and the drive mechanism of the instant invention.

FIG. 3 is a side elevation view of the operator handle and drive mechanism in FIG. 2.

FIG. 4 is a perspective view of the reciprocating gate dispenser shown in FIG. 2.

FIGS. 5 and 6 are enlarged sectional views of two embodiments of drive mechanisms according to the instant invention.

DETAILED DESCRIPTION The transfer xerographic system of FIG. 1 has the drum 1 which includes a photoconductive layer coated onto an electrically grounded metal cylinder. The drum as described defines a continuous, reusable xerographic plate or member. The drum is journaled in a frame to rotate in the direction indicated by the arrow to cause the free or image forming surface of the drum to sequentially pass a plurality of xerographic processing stations.

The charging station A includes the corotron 2. Corotron 2, e.g., that described in U.S. Pat. No. 2,836,725, is coupled to an appropriate electrical potential and positioned relative to the drum to deposit charge on the free surface of the drum so as to elevate the free surface to a substantially uniform electrical potential, e.g., 800 volts.

The exposure station B includes appropriate lamps 3 and lens 4 mounted to cooperate for a line-by-line scan of an original placed face down on copyboard or platen 5. The light image created by the scanning of an original is projected onto the free surface of drum 1 through the aperture 6 in the light stop 7. The electrical potential of the drum drops substantially in the areas of the xerographic plate absorbing the incident light. The areas absorbing the light, in the present positive to positive copying system are referred to herein as the background areas. An example of a background potential is 200 volts when the drum is charged as in the earlier example of 800 volts. The areas of lower potential actually may comprise the image area in a negative to positive copying system. This latter copying system is not discussed in detail to avoid redundancy because the present description applies except for logically necessitated changes.

Adjacent the exposure station is the development station C which contains the toner particles for making the latent electrostatic image visible. FIG. 1 shows a cascade development system, by way of example, which includes a motor driven bucket-type conveyor 10. The developer material 11 includes carrier particles and toner particles and is stored in a sump in the bottom of the housing 11. The buckets scoop up the developer and carry it to the upper portion of the housing where the developer is poured or cascaded over the hopper chute onto the drum 1.

As the developer cascades over the free surface of the drum, the toner particles adhere to the latent electrostatic image because of the electric fields associated with the latent image. The toner is electrostatically charged triboelectrically due to a mixing action with the carrier particles. Toner particles consumed during the development process is replenished by a toner dispenser 13 mounted within housing 11.

The pre-transfer station D includes the pre-transfer corotron 15 and pre-transfer lamp 16. Station D conditions the xerographic plate and toner thereon such that only image area toner particles are transferred to a transfer member 17 at station E. The pre-transfer corotron 15 operation is disclosed in US. Pat. No. 3,444,369 to Malinaric.

The transfer station includes, by way of example, means for feeding a transfer member 17 in registration with the toner image on the drum and the transfer corotron 18 which charges the backside or non-image carrying side of a transfer member to a high potential, e.g., +2,000 volts for the earlier given examples of +800 and +200 volts at the free surface of drum 1. The electric field established by the charge deposited by corotron l8 and the potentials associated with the drum cause the toner particles in image areas to transfer to member 17.

The transferred toner image is permanently fixed to member 17 at the fixing station F. Station F includes, by way of example, electrical heating elements 21 that heat soften the toner particles to bond them to the transfer member.

The cleaning station G includes a cleaning corotron 22 and the rotating brush 23 positioned within vacuum housing 24. Corotron 22 is coupled to an alternating potential source to neutralize any non-transferred toner, that is charge the remaining toner to a new ground potential when the drum is grounded. The brush sweeps up the remaining particles while the vacuum drawn on the housing 24 pulls the toner into a filter located in box 25.

The cleaning station also includes a lamp 26 for flooding the free surface of the drum with light. Thereafter, the drum once again passes station A and the next cycle begins.

The development station C also includes a background electrode 30 positioned inside housing 12 spaced about a half inch from the drum at their closest points. Electrode 30 is electrically biased because it is relatively greatly spaced from the latent image on the drum and because the bias is properly selected, it does not act like a development electrode as taught in Carlson US. Pat. No. 3,147,147. Electrode 30 is biased so as to suppress toner powder clouds which means that fewer toner particles adhere to the drum in the background areas in the first instance. (See for example Robinson US. Pat. No. 3,412,710 and Aser et al. U.S. Pat. No. 3,424,13l). The electrode 30 includes conductive surface facing the drum which is coupled to the high electrical potential. The electrode also includes insulating means to electrically insulate the conductive surface from the housing 12.

Attention is now directed to the reciprocating gate dispenser 13 shown in FIGS. 2 and 4. The dispenser includes a hopper or container 33. Although the hopper or container 33 may be made of any suitable material in any size or shape, the hopper shown is fabricated from sheet metal into a rectangular open-ended box having vertical side walls 34 and end walls 35, the upper ends of the walls being bent outward to form horizontal flanges by means of which the hopper may be attached to a suitable support.

At opposite ends of the hopper are positioned depending bearing blocks or

support members

36 and 37 for supporting the remaining elements of the toner dispenser with the bearing blocks or support members being attached to end walls.

The bottom of the hopper is partially closed by a dispensing plate or platform 40 positioned in spaced vertical relation below the lower edges of the walls of the hopper. The dispensing plate or platform 40 which is as wide as the hopper, is secured to the underside stepped portions of

support members

36 and 37. The dispensing plate or platform 40 combines with the walls of the hopper to provide a reservoir having narrow elongated discharge outlets, discharge passages or gates 41 for the flow of toner particles.

To effect substantially uniform flow of toner particles through the outlets or passages 41 there is provided a metering element, generally designated 42, having a dispensing grid 43 positioned for reciprocating motion in the space between the dispensing platform and the lower edges of the walls of the hopper. The metering element 42 has the dispensing grid formed by a top wall having a series of transverse perforations or slots formed therein, and depending side walls 44. For ease and economy in manufacturing the metering element is formed as a sheet metal stamping, the slots being formed relatively close to each other and to the transverse edges of the top wall so that after the slots were formed there remains only narrow strips of metal simulating wires 45, the width of the metal remaining between slots being only sufficiently wide to prevent them from being bent out of shape in the stamping process.

The metering element 42 is supported by parallel guide rods or rod members 47 extending through holes in plates 48, the ends of the rod members being journaled for reciprocating motion in apertures 49 formed in bearing blocks 36 and 37. The movement of rod members 47 to the left is limited by collars 50 ad justably secured thereto by set screws while movement of the metering element 42 with respect to rod members is prevented by collars secured to the guide rods inboard of the support plates 48.

For effecting movement of the metering element a plunger rod 52 is journaled in third aperture 53 in the bearing block, to be actuated by a suitable power source such as cam 54 to effect the forward stroke of the metering element to the right. To limit the movement of the plunger rod, retaining rings are secured in suitable grooves at each end of the plunger rod. The return stroke of the metering element is effected by coiled springs 55 encircling the rods 47 and abutting at opposite ends against the bearing block and a support plate 48 to bias the metering element to the left.

As shown, the dispensing grid 43 is positioned between dispensing platform 40 and the lower edge of the walls of the hopper in spaced relation to each other to permit free reciprocating movement of the grid. The space or clearance between each of thelast-named elements may be varied during fabrication to accommodate the particle size of toner or other granular material to be dispensed. For example, it has been found that a very satisfactory uniform dispensing rate for toner having a particle size of from 0.7 to 0.9 microns can be had by a toner dispenser in which the spacing between the dispensing platform and the lower edges of the walls of the hopper is between 0.28 to 0.038 inch, preferably 0.033 inch, while the spacing between both the dispensing platform and the dispensing grid and the low edges of the walls of the hopper is between 0.007 to 0.010 inch, preferably 0.0075 inch when using 0.018 inch thick sheet metal for the dispensing grid.

In the operation of the toner dispenser, a supply of toner particles is placed within the hopper, the hopper and dispensing platform forming a reservoir for the toner particles. Upon reciprocating of the dispensing grid 43 toner particles fall onto the dispensing platform and are pushed forward by the individual wires 45. As the toner particles arepushed forward, either on the forward stroke or on the return stroke, they take the path of least resistance and gravitate toward the outer margins of the wires, falling through the open grid work of the dispensing grid and over the edge of the dispensing platform.

The element 42 is shown sufficiently shorter than the length of the hopper so that the collars can be adjusted on rod members 47 to prevent the dispensing grid from striking

support members

36 and 37 as it is reciprocated, the length of stroke also being adjusted so that the path of movement of a wire overlaps the path of movement of the next adjacent wire.

In the embodiment of the toner dispenser shown, the respective spacing between the dispensing platform, the dispensing element or grid and the lower edges of the hopper walls is fixed. Accordingly, the dispenser provides a uniform dispensing rate per stroke or cycle. Therefore, the dispensing rate may be changed by vary ing the dispensing frequency, i.e., the number of strokes or cycles per unit time, or by varying the length of stroke of the dispensing element 42.

In the environment of the xerographic system of FIG. 1, the dispensing frequency is directly proportional to the number of revolutions per unit time of drum 1. This means that the dispensing frequency is directly proportional to the number of copies formed on transfer sheets 17 per unit time. As mentioned at the outset, this described system provides a dispensing rate for toner which is, of course, related to the number of copies generated. The proportionality is provided simply by mechanically coupling the cam 54 to the shaft of drum 1. The dispensing frequency is fixed for the system of FIG. 1 and toner concentrations are scaled up and down by varying the length of travel of dispensing grid 42. This is done by varying the position of the abutment plate 56 relative to the plunger rod 52. The location of plate 56 determines how far the plunger rod can travel to the left. In FIG. 2, the plate is shown located at its left-most position which defines the maximum stroke length. The dashed lines 57 in FIG. 2 indicate the rightmost position of the plate 56.

The abutment plate has shaft 58 coupled normal to the plane of the plate and slidably mounted by a bearing 59 in frame plate 60. Shaft 58 is effectively an extension of the plunger rod 52 in that shaft 58 is reciprocated as cam 54 is rotated about drive shaft 61. The drive shaft 61 is in turn appropriately coupled by belt 62 and pulley 63 for rotation at an angular rate proportional to the rotation of drum 1. In fact, the belt 62 is coupled to a pulley mounted on the shaft of drum 1. Abutment plate 56 is positioned at a location at or between the right and left most positions by the operator controlled handle 64.

Handle 64, in the embodiment of FIGS. 1,3 and 5, is

journaled for rotation in a frame plate 67. The pivotally mounted lever 68 is coupled to the handle by the spring 69. A rigid wire cable 70 is fixedly coupled to lever 68 at one end and fixedly coupled to abutment plate 56 at its opposite end. The cable is passed through the tubing or conduit 70 which in turn is fixedly coupled to the

frame plates

60 and 67 Pivotal movement of handle 64 is translated into linear displacement of abutment plate 56 by the cable, spring and lever connecting the two. Accordingly, the length of travel of the dispensing or metering element 42 is set by operator adjustment of handle 64.

The novel drive mechanisms of the instant invention reset the handle 64 to a standard position when the handle is located by an operator to a position causing a toner dispensing rate greater than that established by the standard handle position. Each drive mechanism includes a one-way clutch coupled at its output side to handle 64, a yoke member 73 coupled to the input side of the clutch, cam peg 74 fixedly coupled to pulley 63 which is in turn mounted on the drive shaft 61 rotating the reciprocating cam 54 and the stop plate 75 fixedly coupled to the frame plate 67.

The present drive mechanisms are able to impart in equal increments a total angular displacement of less than 360, normally around 20 to 30, to the handle in response to continuous rotation of the pulley 63. The yoke 72 and the cam peg 73 tap the continuous rotation of pulley 63 and supply the energy to handle 64 through a one-way clutch. The fork portion 78 of the yoke straddles drive shaft 61 and peg 73. The peg is a cam and the fork is its follower and they act together to impart a back and forth wrench motion to the body 79 of the yoke. The toner setting represented by the angular position of handle 64 is changed by some desired incremental amount during each wrench cycle of the yoke. The change to the toner setting can occur during either the clockwise or counterclockwise rotation of the yoke at the discretion of the designer. One wrench cycle is obtained per one revolution of pulley 63 but this may be scaled up or down.

The object is to remove handle 64 back to the stop pad 75 within a fixed number of revolutions of pulley 63. The location at which the handle abuts pad 75 is selected as the standard handle position defined earlier. Any position of the handle to the right of pad 75 (FIG. 3) yields undesirably high toner dispensing rates as described. Lower toner settings, i.e., settings to the left of pad 75 (FIG. 3), are obtained by moving the location of the stop pad.

The present drive mechanism allows a zero toner dispensing rate. The zero rate is obtained when the handle positions the abutment plate 56 to the rightmost location 57. The shaft 58 is out-of-contact with cam 54 when the abutment plate is at position 57. Consequently, no toner is dispensed at this handle setting. A zero rate may be desirable when a plurality of copies are being made that consume only a small quantity of toner. For example, a zero setting may be desired when the copies include only a one sentence message. The operation of the embodiments of the present drive mechanism may be understood by reference to FIGS.

and 6.

The embodiment of FIG. 5 includes the stop pad 75 and the wrap spring clutch 80 having its input hub 81 fixedly coupled to the common shaft 82 by a set screw 83 and its output hub 84 freely rotatable about shaft 82 and fixedly coupled to lever 68 (best seen in FIG. 3). Lever 68 is coupled to the handle 64 by the coil spring 69. The embodiment of FIG. 5 also includes the yoke member 73 fixedly coupled to the common shaft 82 by means of a set screw 87 in the cap 88 fixedly coupled to the yoke. The handle 64 is journaled for rotation about the threaded barrel 89 which is fixedly coupled to the frame plate 67 by the nut and

washer

90 and 91.

The back and forth wrench motion of the yoke described earlier rotates the input hub 81 of the clutch back and forth. The cylindrical coil spring 94 is loosely fitted over the input 81 and output 84 hubs with tang 95 extending upward free of the clutch housing. When input hub 81 is rotated clockwise, for example, the diameter of the cylindrical coil spring contracts thereby frictionally coupling the two hubs together. Consequently, the output hub and lever 85 follow the rotation of yoke 73. When input hub 81 is rotated counterclockwise, for example, the coil spring is uneffected and the output hub and lever 68 do not follow the rotation of yoke 73.

The handle 64 is incrementally rotated back to the stop pad 75 as a result of the foregoing operation. With the handle restrained by the stop pad, the tripper bar 96 fixedly coupled to handle 64 engages tang 95 and prevents the coil spring from wrapping around the two hubs during the clockwise portion of the wrench cycle of the yoke. Therefore, the output hub 84, and lever 68 do not follow the movement of yoke 73 in either the clockwise or counterclockwise directions while the handle is at the stop pad.

To position the handle against a limit or zero dispensing rate stop, handle 64 is pulled to the left (FIG. 5) to clear the stop pad 75. If it is not positioned against the limit stop, the drive mechanism will move the handle to that position in a time proportional to a multiple ofa number of drum revolutions.

The embodiment of FIG. 6 includes the stop pad and the one-way roller clutch 101 having its input hub 102 fixedly coupled, e.g., welded, to the yoke 73. The hub 102 includes asymmetrical cavities 103 in which the roller bearings 104 are seated. The hub rotates freely about common shaft 105 when yoke 73 is rotated clockwise, for example, and is locked to shaft 105 when yoke 73 is rotated counterclockwise.

Fixedly coupled to the other end of common shaft 105 is the friction slip clutch 106. Clutch 106 includes the first and second hubs 107 and 108 having friction layers 109 and 110 of cork or other high friction material facing each other. The handle 64 is journaled for rotation about the common shaft 105 between the cork surfaces 109 and 110. The frictional forces exerted by the surface of

layers

109 and 110 on the handle are controlled by means of the leaf spring 111. The screw 112 is threaded to mate with threads in the hub 107 and has the leaf spring between it and the hub to vary spring tension when the screw is turned in and out of the threaded hub. The tension in the leaf spring is adjusted by means of screw 112 to enable the friction layers 109 and 110 to rotate handle 64 when the common shaft 105 is rotated. Shaft 105 is rotated on the clockwise, for example, portion of the wrench cycle of yoke 73 as explained earlier.

The handle is angularly displaced in increments by the friction clutch 106 in the manner described until it engages the stop pad 75. The frictional forces between

layers

109 and 110 and the handle are not sufficient to overcome the force exerted on the handle by the stop pad. The friction clutch simply slips or free wheels in this situation. Once again, pulling the handle to the left (FIG. 6) clears it of stop pad 75 and the drive mechanism will pull the handle to a limit or zero concentration handle position. The cable 70 is fixedly coupled directly to the handle 64 in this embodiment rather than by the spring 69 and lever 68 as in the embodiment of FIG. 0.028

The foregoing embodiments may be varied without departing from the scope of the current invention. An example would be to adapt the embodiments described to a system wherein the operator control means is a push button rather than a handle. The basic concept of incrementally stepping toner concentration settings during multiples of a copy forming cycle, or other cycle in which a powder is consumed, may be readily adapted to other environments in light of the present teaching. Accordingly, such modifications are intended as part of this invention.

What is claimed is:

l. Electrostatic imaging apparatus comprising copying means for creating electrostatic latent images on plate members,

developing means positionable relative to a plate member for developing a latent image on the plate forming a toner particle image,

toner particle dispensing means for supplying toner particles to the developing means for the formation of toner particle images,

operator control means coupled to the dispensing means for establishing the quantity of toner particles supplied to the developing means including a plurality of operator selectable toner settings each of which make a different quantity of toner particles available to the developing means and drive means coupled to the control means for changing an operator selected toner setting in response to the number of toner images formed.

2. The apparatus of claim 1 wherein said drive means includes means for incrementally changing said toner setting.

3. The apparatus of claim 1 wherein said drive means includes means for changing an operated selected toner setting to a standard toner setting.

4. The apparatus of claim 1 wherein said plate member includes a xerographic plate and said copying means includes means for electrostatically charging the plate and means for exposing the plate to light to create the latent image.

5. The apparatus of claim 4 wherein said xerographic plate is reusable.

6. The apparatus of claim 1 wherein said dispensing means includes a reciprocating gate dispensing means.

7. The apparatus of claim 1 wherein said control means includes a pivotally supported handle manually adjustable to the plurality of toner settings.

8. The apparatus of claim 6 wherein said dispensing means includes a reciprocating gate dispensing means and said control means includes means for varying the length of travel of a reciprocating member in said dispensing means for sealing the quantity of particles supplied to the developing means.

9. The apparatus of claim 8 wherein said control means includes a pivotally mounted handle coupled to said dispensing means for establishing a different length of travel for the reciprocating means at different angular positions of the handle.

10. The apparatus of claim 1 wherein said control means includes a control shaft adjustable to a plurality of angular settings comprising the toner settings.

11. The apparatus of claim 10 wherein said drive means includes means for angularly displacing said control shaft by some incremental angular amount upon one revolution of a drive member shaft rotated in proportion to a cycle during which a toner image is formed.

12. The apparatus of claim 11 wherein said drive means includes a yoke member coupled at one end to a common shaft and at the other end to the driving member to impart a wrench motion to the yoke member in response to rotation of the driving member shaft and clutch means coupled between said common and control shafts to rotate the control shaft in one direction in response to the wrench motion of the yoke member.

13. The apparatus of claim 12 wherein said drive means further includes stop pad means for limiting the rotation of control shaft to an angular position corresponding to a standard toner setting.

14. The apparatus of claim 12 wherein said clutch means includes roller clutch means coupled between said yoke member and the common shaft and friction clutch means coupled between the control and common shafts.

15. The apparatus of claim 12 wherein said clutch means includes wrap spring clutch means coupled between the common and control shafts.

Claims

1. Electrostatic imaging apparatus comprising copying means for creating electrostatic latent images on plate members, developing means positionable relative to a plate member for developing a latent image on the plate forming a toner particle image, toner particle dispensing means for supplying toner particles to the developing means for the formation of toner particle images, operator control means coupled to the dispensing means for establishing the quantity of toner particles supplied to the developing means including a plurality of operator selectable toner settings each of which make a different quantity of toner particles available to the developing means and drive means coupled to the control means for changing an operator selected toner setting in response to the number of toner images formed.

5. The apparatus of claim 4 wherein said xerographic plate is reusable.

8. The apparatus of claim 6 wherein said dispensing means includes a reciprocating gate dispensing means and said control means includes means for varying the length of travel of a reciprocating member in said dispensing means for scaling the quantity of particles supplied to the developing means.

16. The apparatus of claim 11 wherein said plate member is a continuous xerographic plate and said driving member shaft includes a shaft rotating at an angular velocity related to the recirculating rate of the xerographic plate.

17. The apparatus of claim 11 wherein said control shaft includes a handle coupled thereto for enabling an operator to manually rotate the control shaft to one of the toner settings.