Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS3604939 A
Publication typeGrant
Publication dateSep 14, 1971
Filing dateMay 24, 1968
Priority dateMay 24, 1968
Also published asDE1926198A1, DE1926511A1, US3527387
Publication numberUS 3604939 A, US 3604939A, US-A-3604939, US3604939 A, US3604939A
InventorsLatone Salvatore, Maksymiak John
Original AssigneeXerox Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Toner concentration sensing apparatus having plural sensors and a flow control means for each sensor
US 3604939 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

FIPBZIZ United States Patent I I I I John Maksymiak Penlield;

Salvatore Latone, Rochester, both of, N.Y. 731,756

May 24, 1968 Sept. 14, 1971 Xerox Corporation Rochester, N.Y.


U.S. Cl 250/218, 96/13, 1 18/7, 118/637, 222/1, 222/57, 356/201 Int. Cl "G011 11/00, GOln 21/22, 603g 13/00 Field of Search 250/218;

[56] References Cited UNITED STATES PATENTS 2,611,876 9/1952 Hartman 250/218 3,094,049 6/1963 Snelling.. 118/637 X 3,149,650 9/1964 Horst 222/57 X 3,430,606 3/1969 Pease et al. 1 18/637 3,526,338 9/1970 Goodrich et al. 222/1 Primary Examiner-James W. Lawrence Assistant Examiner-T. N. Grigsby AtlorneysNorman E. Schrader, James .I. Ralabate and Bernard A. Chiama ABSTRACT: A toner concentration sensing apparatus arranged in the circulation path of developing material in an electrostatic reproduction machine and having a housing into which some of the moving developing material is diverted. The apparatus includes means in the housing or splitting the inflowing material into a plurality of paths each of which has associated therewith a toner concentration sensing device all of which cooperate with a toner replenishing means. A timing mechanism is connected to the sensing devices for periodically controlling their operation as toner concentration sensing devices.



SHEET 3 BF 3 o '88, w w 1| 1| o :l 37 A364 NESA POWER SUPPLY THRESHOLD POWER SUPPLY DETECTOR L l g r L gusv eo- .307

(D uFaaa no LOGIC FIG. 6

DEGEES o 9o use 270 {A 0 SHUTDOWN 5+ SAMPLE} c- CLEAN SECONDS 0 L5 3.0 4.5

BY l l ATTORNEYS TONER CONCENTRATION SENSING APPARATUS HAVING PLURAL SENSORS AND A FLOW CONTROL MEANS FOR EACH SENSOR This invention relates to developing apparatus and particularly, to improvements in a toner replenishing system particularly adapted for use in automatic copiers/reproducers that are constructed for high speed operation.

As is well known in recent years, the steadily increasing size of various industries has required an enormous increase in the amount of paper word that must be accomplished, maintained and made available for wide interplant circulation. In the present day commercial automatic copiers/reproduction machines, which are adapted to produce copies of between and 60 8X1 l inches sheets of copy per minute, the photoreceptor device is moved in timed unison relative to a plurality of processing stations and the usual developer system is limited as to the amount and the toner concentration of the developing material that can be conveyed to a development zone for the machine.

The use of photoreceptor devices moving at high speeds require relatively fast flowing or moving developing material in order to effect good solid area development. With large quantities of developing material being consumed, there is a need for insuring at all times optimum mixture conditions of the developing mixture.

It is therefore the principal object of this invention to improve copiers/reproduction machines of the type having a fast moving photoconductor plate by maintaining the mixture relationship of toner particles and carrier heads at a predetermined proportion in order to assure optimum developing con ditions.

Another object of this invention is to control automatically the amount of toner particles in an electrostatic developing system.

These and other objects of this invention are obtained by means of a toner concentration sensor apparatus having devices for conveying developer material through the sensor for sampling purposes and directing the diverted material across two concentration sensing device through which a light beam is projected for testing and density of toner accumulated on the sensing devices. After sampling, the diverted developing material is returned to the main stream of the developer material.

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the I following detailed description of the invention to be read in conjunction with the accompanying drawings, wherein:

FIG. I is a cross-sectional view of a developer assembly in which the present invention may be incorporated;

FIG. 2 is an elevation view, with parts broken away, of the toner concentration sensor device used in the developer assembly;

FIG. 3 is a side view of the toner sensor with parts broken away;

FIG. 4 is a ems-sectional view taken along the line 4-4 in FIG. 2.

FIG. 5 is a fragmentary view of a detail in the toner sensor;

FIG. 6 is a schematic of the control circuit for the toner sensor of FIG. 2.

FIG. 7 is an elevational view of the timer mechanism for the toner sensor;

FIG. 8 is an end view of the timer mechanism and;

FIG. 9 is a timing chart indicating the operative sequence of the timer mechanism.

For a general understanding of the illustrated copier/reproduction machine, in which the invention may be incorporated, reference is had. As in the electrostatic system disclosed in this patent, a light image of a document to be reproduced is projected onto the sensitized surface of a xerographic plate in the form of a belt 12 (see FIG. I) to form an electrostatic latent image thereon. Thereafter, the latent image is developed by a cascade developing apparatus 14 with an oppositely charged developing material to form a xerographic powder image, corresponding to the latent image on the plate surface. The powder image is then electrostatically transferred to a support surface such as sheets of paper to which it may be fused by a fusing device whereby the powder image is caused permanently to adhere to the support surface.

As the developing mixture is cascaded over the xerographic belt 12, toner particles are pulled away from the carrier beads and deposited on the belt to form powder images, while the partially denuded carrier beads and excess toner pass off the belt and into the developer housing 200 by way of the pickoff bafi'le 202. As toner powder images are formed especially for solid area development additional toner particles must be supplied to the developing mixture in proportion to the amount of toner deposited on the selenium belt. To supply additional toner particles to the developing mixture, a toner dispensing system 15 is utilized to accurately meter toner to the developing mixture within the lower portion of the developer housing 200.

The toner dispenser l5 dispenses a uniform quantity of toner for a given stroke length of the metering gate 304, wherein the quantity of toner delivered by the toner dispenser may be varied by the number of strokes of such movement per unit of time. Accurate control of the dispensing rate for the toner dispenser can be accomplished by controlling the time in which the motor M-IO is energized and the rate of reciprocation of the gate 304.

In order to control the dispensing of toner from the toner dispenser 15, there is shown in FIG. 2-9, the details of an automatic toner control system which ultimately controls the time of energization for the dispenser motor M-IO at start up and during continuous operation of the machine.

Basic lly, the utomatic toner dispensing system comprises a tonaatfggl mounted within the developer housing 200 by any SUI a e means which electrically grounds the sensor, a flat funnel bin 341 which conveys some of the developer material passing through a slot 285 in the plate 220 into the sensor 340. As shown in FIG. 1, developer material entering the bin 34!, slides downwardly to the left along the inclined plane of the bin. The plate 3 42 supports an upstanding deflector plate 344 in the path of the downwardly moving material.. A suitable conduit is arranged to conduct the flow of the developer material that does not enter the sensor 340 back into the developing apparatus 14 for continued circulation of the material.

The tone sensor 340 is generally square in shape having a relatively narrow depth, and resembling a flat box-shaped housing. It is arranged such that diagonal corners are aligned with the vertical in order to permit the flow of toner into the upper corner and to permit egress from the sensor from the diagonally placed lower corner. Within the sensor housing, there is positioned at the upper comer of the housing, a triangular shaped baffle element 345 which has the apex of a comet thereof facing upwardly into the path of the free-falling developer material which flows through a conduit 346 connnected between the upper comer of the housing and an opening 347 formed in the bin 341. The angled element 345 serves to split the downwardly flowing developer material into two separate paths of approximately equal flowing widths. The developer material flowing along the left path, as viewed in FIG. 2, slides along one leg 348 of the angled element 345 and along an extension of the leg in the form of an adjustable control gate 349 until the development material has its flow obstructed by a guide baffle plate 350 positioned relative to the path of movement of the development material and the plane of the gate 349. The lower end of the control gate 349 is spaced from the guide plate 350 a narrow distance to permit a controlled amount of the developer material to change its direction of flow 90, or toward the lower right corner as viewed in FIG. 2. Excess developer material, or that material which does not pass between the edge of the gate 349 and the plate 350, flows around the outer end thereof along the lower angled bottom walls of the sensor 340 and to an outlet tube to be described. The developer material now slides in this direction along the guide plate 350 and onto a conductive glass plate 351 secured thereon and across which the developer material flows. A sensing photocell P-l is secured to the sensor housing immediately below the plate 351 for a purpose to be described hereinafter.

Similarly, the element 345 has a second leg which is adapted to convey development material along another path of movement upon entering the sensor 340. This leg 352 is also provided with a projecting extension in the form of a control gate 353which directs development material downwardly and to the right and against a second guide plate 354 positioned 90 to the flow of the development material in this trunk and relative to the gate 353. As was the case with the guide plate 350, a second conductive glass plate 355 is insulatingly attached to the plate 354 across which development material is directed as the material is permitted to flow through the lower edge of the gate 355 and the adjacent surface of the plate 354 in a controlled quantity manner. A lamp LMP-l is mounted immediately below the plate 355 and arranged so that when energized, some of the lights rays therefrom will be transmitted through both NESA plates and impinge upon the photocell P-l.

The development material which has passed across the plates 351 and 355 and which pass as an overflow across the ends of the guide plates 350 and 354 are brought together again at the lower comer of the sensor housing 340 and into an outlet tube 356 which is in communication with this lower 'corner. The lower end of the pipe 356 is in communication with portions of the developing assembly 14 in order to return developing material to the system.

Each of the sensing plates 351 and 355 has a thin transparent layer of a conductive oxide, preferably formed of NESA" glass, a trademark of the Pittsburgh Glass Company, which is generally a tin oxide coated glass that is transparent to white light. Since both plates are mirror images of each other, details of only one of the plates will be described. A pattern 357 is formed on the plate 351 as shown in FIG. 5 and is of L-shape being produced by scribing through the oxide layer in order to electrically separate the pattern 357 from the remaining portion 358. Each of the conductive portions 357, 358 are connected to a circuit to be described hereinafter.

In order to accumulate toner in an amount fairly indicative of the total of the total amount of toner in the developing system, the patterns 357 on both plates 351 and 355 have applied thereto an electrical potential of a polarity and amount to attract and retain toner particles for some predetermined unit of time. During this time, the light transmission through the accumulated toner on both patterns 357 will be determined in terms of toner concentration for the developer material. When the predetermined unit of time has terminated and after the toner accumulation is sensed, the polarity on the patterns 357 of the sensing plates is reversed in order to permit the patterns to repel toner particles thereby effecting the cleaning of the patterns by means of the developer material allowed to continue flowing across the patterns brushing toner therefrom.

As shown in FIG. 6, the conductive portions of each of the plates 35], 355 are connected in parallel and to a timer mechanism generally indicated by the reference numeral 360, shown in detail in FIGS. 7 and 8. The timer mechanism 360 is in the form of a continuously rotating bank of cams which periodically make and break switches connected to the toner sensor circuit. The timer comprises a motor M-6 connected to a gear reduction drive mechanism 362 which has its output shaft connected to a shaft 363 rotatably mounted on a frame 364 for the timer mechanism. The shaft 363 has mounted thereon for rotation therewith a first cam 365 for controlling the electrical supply to the timer drive motor M-6 during shutdown of the xerographic machine, a second cam 366 which control the time during which the accumulated toner on each of the plates 351 and 355 is sampled and, a third cam 367 which controls the polarity upon the plates 351,355. The cam 365 assures that a positive polarity is applied to the patterns 357 whenever the sensor is "cycled out for a purpose to be described hereinafter.

The first cam 365 is formed with a control lobe 368 which is arranged to actuate an actuator 370 for a switch 371 which is connected to a suitable source of electrical power supply to the timer motor M-6. This motor is energized whenever a main switch in the electrical circuit for the machine is closed and the drive for the developing system conveyors is activated. During the shutdown of the machine when it is still processing a last copy, the switch 371 will maintain the motor M-6 energized for a complete sensing cycle which, as will be further described, lasts for about 6 seconds. The developer material used in this last cycle is furnished from the conduit 346 which serves as a sump for this purpose. Closing of the switch 371 assures shutdown of the motor M-6 only when the regions 357 having a positive polarity or that polarity opposite that of the toner particles utilized.

Before proceeding further in the description of the timer circuit a brief description of the sensing and nonsensing mode of operation for the toner sensor will be described in relation to the timer 360 and the electrical power thereto.

The circuit for the toner sensor and the components thereto are arranged and programmed so that sensing of toner concentration occurs periodically and asymmetrically, that is, for a short, predetermined time interval, or, after a relatively long predetermined time period. For purposes of illustration of these time periods and controls, the sensor control circuit is adapted to sample or sense the toner concentration accumulated upon the patterns 357 for a period of one-tenth of a second, which period occurs after the patterns are in the attract" mode for about four-tenths of a second prior to sampling. During the attract" mode which encompasses the sampling period, the patterns 357 are of positive polarity or that polarity opposite the polarity on the toner particles. After approximately one-tenth of a second for the sampling" period, the electrical power for this sensing function will be terminated until the next cycle. The cycle of placing the sensor in the attract" condition, sampling, and cleaning the sensor occurs every 6 seconds when the xerographic machine is in the continuous print mode of operation. In the illustrated example, with the attract" mode lasting approximately fivetenths of a second and the clean" cycle tive and one-half seconds, the toner density sensing is asymmetrical in its cycling.

As shown in FIG. 9, there is illustrated a series of time graphs for a 6 second cycle of toner concentration sampling and control. During this 6 seconds, the output shaft 363 for rotating each of the cams 365, 366 and 367 makes one complete revolution. As previously stated, the switch 371 is actuated by the cam lobe 368 on the cam 365 and comes into service only for the last 6 second sensing cycle during processing of the last copy of a particular production run. The circular length of the lobe 368 is such as to maintain closing of the circuit to the timer motor M-6 for nearly the entire 6 second period and as shown in FIG. 9, the switch 371 is actuated to a closed position until approximately 5.85 seconds has transpired or when the cam reaches the line 372 on the curve A. During use of the machine before the last copy is being processed, the switch 371 is bypassed. It is, in effect, an auxiliary AC path to assure shutdown in the "attract" mode. At the end of the 6 second period the switch 371 is again actuated to a closed condition commencing the next cycle of sensor control.

As shown by the time curve B, just prior to reaching the line 372, the cam 367 which actuates a normally closed switch 373 to an open position and a normally open switch 374 to a closed position causes these switches to be actuated such that the normally open switch 373 closes to cause the patterns 357 to be supplied with positive potential from the power supply 375, thereby holding the patterns in the "attract" mode. This attract mode will remain until the termination of the 6 second cycling period. This is illustrated in the timing curve B by the line 376. Simultaneous with this actuation of the switch 373 is the actuation of the normally closed switch 374 which when open prevents the flow of negative potential to the areas 358 of each of the sensor plates 351, 355. This occurrence is illustrated in time curve C by the line 377.

After the plates 351, 355 have been placed in the attract" mode for approximately four-tenths of a second, the cam 366 actuates a switch 378 which controls activation of a control circuit in a threshold detector 379 for conditioning the photocell P-l to vary its resistance in accordance with the intensity of the light rays from the continually energized lamp LMP-l. This sample" period remains for approximately onetenth of a second, starting from the sampling "ON" time when the photocell P-l is energized, illustrated by the line 380 in time curve D. As shown in FIG. 8, the control end of the lobe 368 for the cam 365 is spaced angularly from the control end of the lobe 381 for the cam 366 and also spaced from the control end of the lobe 382 for the cam 367, The angular relationship between the lobes 382 and 381 is such as to permit the elapsed time between the beginning of the attract" mode and the instant that the photocell P-l is energized. The angular distance between the lobes 382 and 368 is such that the patterns 357 are energized to a positive potential before the motor M-6 is deenergized in the processing ofa last copy.

For illustrative purposes, the polarity indicated in FIGS. 5 and 6 in relation to the sensing plates 351, 355 are those polarities of the supply voltage when the plates are in the attract" mode. For this invention then, it was assumed that the charge upon toner particles is negative and, therefore, would be attracted to the control patterns 357 for each of the sensing plates. lt is also assumed that the other conductive areas 358 are being supplied with negative DC potential. This electrical configuration is merely illustrative and has been chosen for descriptive purposes because of the particular charge chosen for the toner particles which, as previously stated, is negative. The positioning then of the actuator arms for the switches 373 and 374 is such that toner particles will be attracted to the patterns 357 and repelled from the patterns 358.

As previously stated, in order to exhibit high sensitivity and rapid response time, the electrical circuit shown in FIG. 6 is adapted to periodic sensing action, for every six second period during which the reproduction machine is in continuous operation. During the "attract mode, the toner will accumulate upon the patterns 357 and, in an amount indicative of the amount of toner in the developer material. When the timer 360 has effected switching of the switches 373, 374 the polarity of the patterns 357 and the portions 358 are reversed where upon the pattern 357 assumed a negative polarity and the portions 358 a positive potential. In this manner, the control patterns 357 will repel the toner cascading, down the inclined plates 351 and 355 during this portion of the control cycle. When the polarity is thus reversed, the patterns 357 are cleaned by the cascading developer material and thereby is preconditioned during this clean cycle for another "attract" cycle.

In order to determine the extent of toner concentration that as accumulated on both control patterns 357, the toner sensor 340 is provided with the photocell lamp combination P-1 and LMP-1. As previously stated, the photocell is positioned adjacent the lower surface of the plate 351 so that toner partii cles cascading through the toner sensor and accumulating upon both regions 357 will intercept light rays from the lamp LMP-l positioned behind the lower surface of the other plate 355. The photocell P-l in effect will see light rays which traverses the cascading developer stream flowing upon both plates 351, 355 and, the accumulated toner particles on each of the patterns 357.

Electrically the photocell P-l is connected to the threshold detector 379 in form of a Schmitt trigger which is adapted to produce a pulse when the resistance in the photocell attains a predetermined value indicative of the intensity of the light rays that reach the photocell from the lamp LMP-l during the "sample" cycle. The detector 379 derives its power from a power supply 386 which also supplies the lamp LMP-l wiith its electrical energy.

The pulse generated from the Schmitt trigger 379 is fed to a machine logic circuit 387 which, when combined with other necessary signals from the reproduction machine, is fed to a timer relay 388 by way of an amplifier 390 and then to the toner dispenser motor M-10 connected in series with the relay contact for the relay 388. The timer relay 388 is arranged to remain "ON" for any adjustable predetermined time period for each pulse thereto from the threshold detector 379. For each pulse fed to the timer relay, the motor M-lO will remain energized until the timer period, which may be in the range from 1-10 seconds, has terminated whereupon the motor M-10 will become deenergized for that pulse. As previously stated during energization of the motor M-10 the metering gate 304 is cyclically moved.

During normal operation of the automatic toner dispensing apparatus, the light source LMP-l is continuously energized for presenting light for both plates 351 and 355 arranged optically in series. The light rays which traverse both of these plates impinges upon the photocell P-l which is compared with predetermined values in the Schmitt trigger 379, ln the event that the predetermined value is not exceeded during the sampling step wherein the photocell is energized, the excess is utilized to produce a pulse which is fed to the logic 387 as an indication that the toner concentration in the development material is below a desired level.

As the density of the toner that cascades over the sensing plates 351, 355 increases, the signal on the photocell P-l will be in balance with the predetermined value in the Schmitt trigger 379 thereby terminating periodic energization of the motor M-l0.

lt g be apprgciated that with the presence of both sensing plates 5, the sensitivity of the sensing circuit is relatively high since there is a much wider range of variation that light rays may experience in reaching the photocell P-l. This also results in the control of a relatively wide density range that the xerographic reproductions may attain, or in other words, the density that the toner concentration maintains can be closely regulated. With this narrow range of variations and with continuous short sampling time per unit of time, the xerographic machine is capable of experiencing a relatively narrow, high quality contrast control since the slightest unbalance will demand toner and produce replenishment thereof.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration, and that the invention may be modified and embodied in various other forms without departing from the scope of the appended claims.

What is claimed is:

1. A toner sensing arrangement use in an electrostatic reproduction machine of the type using developing material containing toner particles and having a developing system which circulates the developing material in a continuous path of movement the developing material being utilized to produce a developed image from an electrostatic latent image and having a toner sensing housing, means arranged in the path of movement for the developing material for diverting some of the material and conveying the same into the housing and means positioned in the housing for forming a plurality of flow paths of the conveyed developing material, the improvement comprising flow control means associated with each of said paths for effecting a predetermined amount of flow of the material in the respective paths and thereby produce a control path for each of said flow paths,

a plurality of devices sensitive to a condition of the toner in the developing material arranged in the housing so that each of said control paths has one of said sensitive devices associated therewith,

7 8 and condition responsive means connected to all of said developing material for formingaplurality off'low paths of the sensitive devices for determining the extent of a condition developing material, the improvement comprising of the toner particles as the material comes under the inflow control means associated with each of said paths for effluence of all the devices. fecting a predetermined amount of flow of the material in 2. The toner sensing arrangement of claim 1 wherein said 5 the respective paths and thereby produce a control path sensitive devices are in the form of a transparent conductive for each of said flow paths, m terial nd a o t ol th of h d v l i i l i h a plurality of devices sensitive to a condition of the toner in housing is directed across a surface of a sensitive device. h e op ng ri l rr ng d S thal ea h of Said COD- 3. A toner sensing arrangement for use in an electrostatic PathS has one Of the Sensitive devices o i ted reproduction machine of the type using developing material containing toner particles and having a developing system 531d fl f fesponslve a connected to offald which circulates the developing material in a continuous path Sensmve devlces for determmmg the extem ofa condmo" of the toner particles as the material comes under the inof movement the developing material being utilized to fluence of all the devices.

produce a developed image from an electrostatic latent image and having means arranged in the path of movement for the

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2611876 *Jan 17, 1951Sep 23, 1952Remington Arms Co IncInspection device
US3094049 *Feb 3, 1961Jun 18, 1963Xerox CorpXerographic developer measuring apparatus
US3149650 *Aug 30, 1960Sep 22, 1964Armstrong Cork CoAdmittance meter and dielectric control system
US3430606 *Jan 2, 1968Mar 4, 1969Xerox CorpElectroscopic particle sensor
US3526338 *Jan 2, 1968Sep 1, 1970Xerox CorpMethod and controller for dispensing electroscopic material
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3756192 *Dec 17, 1971Sep 4, 1973IbmAutomatic toner concentration control system
US3777173 *Feb 22, 1972Dec 4, 1973Dyke Res VanXerographic toner concentration measuring apparatus and method
US3791744 *Feb 22, 1972Feb 12, 1974Dyk Res Corp VanXerographic toner concentration measuring apparatus and method
US3870197 *Jun 21, 1973Mar 11, 1975Dyk Research Corp VanXerographic toner concentration control apparatus
US3897748 *May 16, 1974Aug 5, 1975Konishiroku Photo IndApparatus for controlling toner concentration of developer in electrostatic development
US3924462 *Aug 7, 1972Dec 9, 1975Hoechst AgMethod of measuring the toner concentration of a developer circulating in an electrophotographic reproduction machine
US4043293 *May 3, 1976Aug 23, 1977Xerox CorporationDevelopability regulating apparatus
US4256402 *Aug 23, 1978Mar 17, 1981Olympus Optical Co. Ltd.Method and apparatus of detecting toner concentration of dry developer
US4919073 *Feb 28, 1989Apr 24, 1990Dainippon Screen Mfg. Co., Ltd.Surface treatment method and apparatus thereof
US5581335 *Nov 4, 1994Dec 3, 1996Xerox CorporationProgrammable toner concentration and temperature sensor interface method and apparatus
U.S. Classification399/27, 356/432, 118/699, 118/690, 222/57, 222/1, 399/62
International ClassificationG03G15/08
Cooperative ClassificationG03G15/0827
European ClassificationG03G15/08H1L