Xerographic toner concentration control apparatus

Claim 2

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; supply means for periodically providing a stream of said developer, said supply means including a developer sample chamber, and an orifice communicating with said chamber for limiting the rate of flow of the developer in said stream; a supply conduit for transporting said developer to said chamber from the developer tank of said copying apparatus; a valve element comprising a rotatable vane within said chamber for permitting developer to enter said chamber from said supply conduit during a first recurrent time interval and for permitting developer to leave said chamber through said orifice during a second recurrent time interval; a valve drive motor for rotating said vane; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion during intervals when said stream is not impinging on said collecting plate; and control means coupled to said sensing means for varying the concentration of toner in the developer within said tank in accordance with the amount of toner deposited in the form of said layer on said collecting plate portion.

Claim 3

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; supply means for periodically providing a stream of said developer, said supply means including a developer sample chamber, and an orifice communicating with said chamber for limiting the rate of flow of the developer in said stream; a supply conduit for transporting said developer to said chamber from the developer tank of said copying apparatus; a valve element comprising a rotatable vane within said chamber for permitting developer to enter said chamber from said supply conduit during a first recurrent time interval and for permitting developer to leave said chamber through said orifice during a second recurrent time interval; a valve drive motor for rotating said vane; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion during intervals when said stream is not impinging on said collecting plate; and control means coupled to said sensing means for varying the concentration of toner in the developer within said tank in accordance with the amount of toner deposited in the form of said layer on said collecting plate portion.

Claim 4

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; supply means for periodically providing a stream of said developer, said supply means including a developer sample chamber, and an orifice communicating with said chamber for limiting the rate of flow of the developer in said stream; a supply conduit for transporting said developer to said chamber from the developer tank of said copying apparatus; a valve element comprising a rotatable vane within said chamber for permitting developer to enter said chamber from said supply conduit during a first recurrent time interval and for permitting developer to leave said chamber through said orifice during a second recurrent time interval; a valve drive motor for rotating said vane; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion during intervals when said stream is not impinging on said collecting plate; and control means coupled to said sensing means for varying the concentration of toner in the developer within said tank in accordance with the amount of toner deposited in the form of said layer on said collecting plate portion.

Claim 5

Apparatus according to claim 1, further including means for deriving a toner concentration signal from said sensing means, said control means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to each said second recurrent time interval, and (iv) toner dispensing means for varying the supply of toner to the developer within said tank in accordance with the content of said memory.

Claim 6

Apparatus according to claim 2, further including signal delay means for inhibiting the operation of said gating means to prevent coupling of said concentration correction signal to said memory for a predetermined initial period after operation of the copying apparatus is initiated.

Claim 7

Apparatus for controlling the toner concentration of the developer in the developer tank of a xerographic copying apparatus, comprising: a developer sample chamber; a supply conduit for transporting a portion of the developer in said tank to said chamber; at least two orifices communicating with said chamber; a valve in said chamber for periodically permitting developer in said chamber to flow through said orifices in streams; at least one developer stream deflecting element situated below said orifices for disrupting the flow of developer in said streams; first and second inclined light transmissive toner collecting plates situated in the paths of respective ones of said streams; the vertical distances between said orifices and said deflecting element, the orientation and shape of said deflecting element, and the vertical distance between the portion of Said deflecting element which contacts said streams and the portions of said collecting plates which contact said streams being selected to cause said streams to impinge upon said collecting plate portions with kinetic energy sufficient to dislodge toner particles from the developer carrier beads to which the particles are electroscopically adherent, said dislodged toner particles being deposited upon said collecting plate portions, the kinetic energy and turbulence of said developer streams being sufficient to remove toner particles from said collecting plate portions when the concentration of toner in said streams decreases, said kinetic energy being sufficiently low so that the developer is not damaged by impact with said collecting plates; at least one light source for illuminating said collecting plate portions; a photosensitive element for generating a toner concentration signal responsive to the light from said source which is transmitted through said collecting plate portions; control mans coupled to said photosensitive element for varying the concentration of toner in the developer within said tank in accordance with said toner concentration signal; gating means coupled to said valve for preventing utilization of said toner concentration signal by said control means when said developer streams are flowing through said orifices to impinge upon said collecting plates; and conduit means for returning the developer in said streams to said tank after the streams have impinged on said collecting plates.

Claim 8

Apparatus for controlling the toner concentration of the developer in the developer tank of a xerographic copying apparatus, comprising: a developer sample chamber; a supply conduit for transporting a portion of the developer in said tank to said chamber; at least two orifices communicating with said chamber; a valve in said chamber for periodically permitting developer in said chamber to flow through said orifices in streams; at least one developer stream deflecting element situated below said orifices for disrupting the flow of developer in said streams; first and second inclined light transmissive toner collecting plates situated in the paths of respective ones of said streams; the vertical distances between said orifices and said deflecting element, the orientation and shape of said deflecting element, and the vertical distance between the portion of Said deflecting element which contacts said streams and the portions of said collecting plates which contact said streams being selected to cause said streams to impinge upon said collecting plate portions with kinetic energy sufficient to dislodge toner particles from the developer carrier beads to which the particles are electroscopically adherent, said dislodged toner particles being deposited upon said collecting plate portions, the kinetic energy and turbulence of said developer streams being sufficient to remove toner particles from said collecting plate portions when the concentration of toner in said streams decreases, said kinetic energy being sufficiently low so that the developer is not damaged by impact with said collecting plates; at least one light source for illuminating said collecting plate portions; a photosensitive element for generating a toner concentration signal responsive to the light from said source which is transmitted through said collecting plate portions; control mans coupled to said photosensitive element for varying the concentration of toner in the developer within said tank in accordance with said toner concentration signal; gating means coupled to said valve for preventing utilization of said toner concentration signal by said control means when said developer streams are flowing through said orifices to impinge upon said collecting plates; and conduit means for returning the developer in said streams to said tank after the streams have impinged on said collecting plates.

Claim 9

Apparatus according to claim 4, wherein said collecting plates are disposed below said deflecting element and the normals to said plates are inclined at an angle on the order of 30* to 75* with respect to the vertical.

Claim 10

Apparatus according to claim 5, wherein said angles are on the order of 60*.

Claim 11

Apparatus according to claim 5, wherein the vertical distances between said orifices and the adjacent portions of said deflecting element directly beneath said orifices are on the order of three-sixteenths inch.

Claim 12

Apparatus according to claim 7, wherein the vertical distances between said collecting plate portions and the parts of said deflecting element above said plate portions are on the order of 0.25 inch.

Claim 13

Apparatus according to claim 4, further including a bypass conduit for returning a portion of any developer in said chamber to said developer tank without permitting said developer portion to impinge on said collecting plates, said developer portion being returned at a sufficient rate to insure that the concentration of toner in the developer within said chamber is at all times substantially equal to the concentration of toner in the developer within said tank.

Claim 14

Apparatus according to claim 9, wherein said light source and said photosensitive element are situated in dust-free compartments.

Claim 15

Apparatus according to claim 10, wherein the carrier beads of said developer comprise steel pellets having a coating thereon of a material removed from the material of said toner in the triboelectric series.

Claim 16

Apparatus according to claim 11, wherein said deflecting element is electrically conductive.

Claim 17

Apparatus according to claim 12, wherein said deflecting element is grounded.

Claim 18

Apparatus according to claim 12, wherein said deflecting element comprises aluminum.

Claim 19

Apparatus for controlling the toner concentration of the developer in the developer tank of a xerographic copying apparatus, comprising: a toner collecting plate; flow control supply means including a periodically operated valve assembly for providing a stream of said developer only at recurrent periodic intervals; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting pLate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion, said sensing means including gating means coupled to said valve assembly for rendering said sensing means operative only at times between said intervals when said stream is not impinging on said collecting plate; and control means coupled to said sensing means for varying the concentration of toner in the developer within said tank in accordance with the amount of toner deposited in the form of said layer on said collecting plate portion.

Claim 20

Apparatus for controlling the toner concentration of the developer in the developer tank of a xerographic copying apparatus, comprising: a toner collecting plate; flow control supply means including a periodically operated valve assembly for providing a stream of said developer only at recurrent periodic intervals; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting pLate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion, said sensing means including gating means coupled to said valve assembly for rendering said sensing means operative only at times between said intervals when said stream is not impinging on said collecting plate; and control means coupled to said sensing means for varying the concentration of toner in the developer within said tank in accordance with the amount of toner deposited in the form of said layer on said collecting plate portion.

Claim 21

Apparatus according to claim 15, further including means for introducing a substantial amount of turbulence into said periodic stream.

Claim 22

Apparatus according to claim 16, wherein the kinetic energy of said stream is sufficiently low so that the developer in said stream is not damaged by impact with said collecting plate.

Claim 23

Apparatus according to claim 15, wherein said toner collecting plate is light transmissive and said sensing means includes a light source for illuminating said collecting plate and a photosensitive element for detecting the light transmitted through said plate by said source.

Claim 24

Apparatus according to claim 18, wherein said light source and photosensitive element are situated in first and second respective dust-free housings.

Claim 25

Apparatus according to claim 15, wherein said supply means includes an orifice for limiting the rate of flow of the developer in said stream.

Claim 26

Apparatus according to claim 20, wherein said supply means includes a developer sample chamber, said orifice communicating with said chamber.

Claim 27

Apparatus according to claim 21, further including a supply conduit for transporting said developer to said chamber.

Claim 28

Apparatus according to claim 22, further comprising a valve element within said chamber for permitting developer to enter said chamber from said supply conduit during a first recurrent time interval and for permitting developer to leave said chamber through said orifice during a second recurrent time interval.

Claim 29

Apparatus according to claim 20, further including a developer stream deflecting member disposed below said orifice for introducing a substantial amount of turbulence into said stream.

Claim 30

Apparatus according to claim 24, wherein the normal to the collecting plate is inclined at an angle on the order of 30 to 75 degrees with respect to the vertical.

Claim 31

Apparatus according to claim 25, wherein said angle is on the order of 60*.

Claim 32

Apparatus for controlling the toner concentration of the developer in the developer tank of a xerographic copying apparatus, comprising: a developer sample chamber; a supply conduit for transporting a portion of the developer in said tank to said chamber; at least two orifices communicating with said chamber; a valve in said chamber for periodically permitting developer in said chamber to flow through said orifices in streams; at least one developer stream deflecting element situated below said orifices for disrupting the flow of developer in said streams; first and second inclined light transmissive toner collecting plates situated in the paths of respective ones of said streams; the vertical distances between said orifices and said deflecting element, the orientation and shape of said deflecting element, and the vertical distance between the portion of said deflecting element which contacts said streams and the portions of said collecting plates which contact said streams being selected to cause said streams to impinge upon said collecting plate portions with kinetic energy sufficient to dislodge toner particles from the developer carrier beads to which the particles are electroscopically adherent, said dislodged toner particles being deposited upon said collecting plate portions, the kinetic energy and turbulence Of said developer streams being sufficient to remove toner particles from said collecting plate portions when the concentration of toner in said streams decreases, said kinetic energy being sufficiently low so that the developer is not damaged by impact with said collecting plates; at least one light source for illuminating said collecting plate portions; a photosensitive element for generating a toner concentration signal responsive to the light from said source which is transmitted through said collecting plate portions; means coupled to said photosensitive element for varying the concentration of toner in the developer within said tank in accordance with said toner concentration signal, said concentration varying means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to the times when developer is flowing through said orifices, and (iv) toner dispensing means for varying the supply of toner to the developer within said tank in accordance with the content of said memory; and conduit means for returning the developer in said streams to said tank after the streams have impinged on said collecting plates.

Claim 33

Apparatus for controlling the toner concentration of the developer in the developer tank of a xerographic copying apparatus, comprising: a developer sample chamber; a supply conduit for transporting a portion of the developer in said tank to said chamber; at least two orifices communicating with said chamber; a valve in said chamber for periodically permitting developer in said chamber to flow through said orifices in streams; at least one developer stream deflecting element situated below said orifices for disrupting the flow of developer in said streams; first and second inclined light transmissive toner collecting plates situated in the paths of respective ones of said streams; the vertical distances between said orifices and said deflecting element, the orientation and shape of said deflecting element, and the vertical distance between the portion of said deflecting element which contacts said streams and the portions of said collecting plates which contact said streams being selected to cause said streams to impinge upon said collecting plate portions with kinetic energy sufficient to dislodge toner particles from the developer carrier beads to which the particles are electroscopically adherent, said dislodged toner particles being deposited upon said collecting plate portions, the kinetic energy and turbulence Of said developer streams being sufficient to remove toner particles from said collecting plate portions when the concentration of toner in said streams decreases, said kinetic energy being sufficiently low so that the developer is not damaged by impact with said collecting plates; at least one light source for illuminating said collecting plate portions; a photosensitive element for generating a toner concentration signal responsive to the light from said source which is transmitted through said collecting plate portions; means coupled to said photosensitive element for varying the concentration of toner in the developer within said tank in accordance with said toner concentration signal, said concentration varying means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to the times when developer is flowing through said orifices, and (iv) toner dispensing means for varying the supply of toner to the developer within said tank in accordance with the content of said memory; and conduit means for returning the developer in said streams to said tank after the streams have impinged on said collecting plates.

Claim 34

Apparatus according to claim 27, further including signal delay means for inhibiting the operation of said gating means to prevent coupling of said concentration correction signal to said memory for a predetermined initial period after opertion of the copying apparatus is initiated.

Claim 35

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; flow control supply means for providing a stream of said developer only at recurrent periodic intervals; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion, said sensing means being operative only at times between said intervals when said stream is not impinging on said collecting plate; means for deriving a toner concentration signal from said sensing means; and control means for varying the concentration of toner in the developer within said tank in accordance with said toner concentration signal, said control means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to each of said recurrent periodic intervals, and (iv) toner dispensing means for varying the supply of toner to the developer within said tank in accordance with the content of said memory.

Claim 36

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; flow control supply means for providing a stream of said developer only at recurrent periodic intervals; means for directing said periodic stream onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion, said sensing means being operative only at times between said intervals when said stream is not impinging on said collecting plate; means for deriving a toner concentration signal from said sensing means; and control means for varying the concentration of toner in the developer within said tank in accordance with said toner concentration signal, said control means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to each of said recurrent periodic intervals, and (iv) toner dispensing means for varying the supply of toner to the developer within said tank in accordance with the content of said memory.

Claim 37

Apparatus according to claim 29, further including signal delay means for inhibiting the operation of said gating means to prevent coupling of said concentration correction signal to said memory for a predetermined initial period after operation of the copying apparatus is initiated.

Claim 38

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; flow control supply means for providing a stream of said developer only at recurrent periodic intervals, said supply means including (i) a developer sample chamber and (ii) an orifice communicating with said chaMber for limiting the rate of flow of the developer in said stream; a supply conduit for transporting said developer to said chamber; a valve element comprising a rotatable vane within said chamber for permitting developer to enter said chamber from said supply conduit during a first recurrent time interval and for permitting developer to leave said chamber through said orifice during a second recurrent time interval; a valve drive motor for rotating said vane; means for directing the periodic stream leaving said chamber onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion, said sensing means being operative only at times between said intervals when said stream is not impinging on said collecting plate; means for deriving a toner concentration signal from said sensing means; and control means for varying the concentration of toner in the developer within said apparatus in accordance with said toner concentration signal, said control means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to each said second recurrent time interval, and (iv) toner dispensing means for varying the supply of toner to the developer within said apparatus in accordance with the content of said memory.

Claim 39

Apparatus for controlling the toner concentration in the developer of a xerographic copying apparatus, comprising: a toner collecting plate; flow control supply means for providing a stream of said developer only at recurrent periodic intervals, said supply means including (i) a developer sample chamber and (ii) an orifice communicating with said chaMber for limiting the rate of flow of the developer in said stream; a supply conduit for transporting said developer to said chamber; a valve element comprising a rotatable vane within said chamber for permitting developer to enter said chamber from said supply conduit during a first recurrent time interval and for permitting developer to leave said chamber through said orifice during a second recurrent time interval; a valve drive motor for rotating said vane; means for directing the periodic stream leaving said chamber onto a surface of said collecting plate to (i) cause toner particles to be dislodged from the developer carrier granules to which the particles are electroscopically adherent to deposit a layer of toner on at least a portion of said collecting plate and (ii) remove toner from said collecting plate portion when the concentration of toner in said periodic stream decreases; means for sensing the amount of toner deposited in the form of said layer on said collecting plate portion, said sensing means being operative only at times between said intervals when said stream is not impinging on said collecting plate; means for deriving a toner concentration signal from said sensing means; and control means for varying the concentration of toner in the developer within said apparatus in accordance with said toner concentration signal, said control means including (i) means for comparing said toner concentration signal with a reference signal indicative of a desired toner concentration to generate a concentration correction signal, (ii) a memory, (iii) gating means for coupling said concentration correction signal to said memory at times other than those corresponding to each said second recurrent time interval, and (iv) toner dispensing means for varying the supply of toner to the developer within said apparatus in accordance with the content of said memory.

Claim 40

Apparatus according to claim 31, further including means responsive to the angular position of said vane for generating a gating signal at times other than those corresponding to each said second recurrent time interval.