Balance type toner concentration sensing and monitoring system

Claim 2

A toner monitoring system for electrophotographic apparatus incorporating a toner dispensing means for replenishing a developer mixture of toner and carrier with toner when required, comprising: developer means for moving a predetermined quantity of developer mixture to a point of utilization in said apparatus; monitoring means capable of storing only a sampling portion of said developer mixture, said sampling portion being relatively small in relation to said predetermined quantity of developer mixture for monitoring the density of developer mixture during its movement by comparing developer mixture weight with a reference weight; and means controlled by said monitoring means for actuating said toner dispensing means to replenish said developer mixture in said developer means in order to maintain a desired proportion of toner and carrier in said mixture.

Claim 3

The system of claim 1, further comprising: a flow tube incorporated in said monitoring means, said flow tube having an entry portion and an exit portion; mounting means for mounting said flow tube on said developer means for entry of a said sampling portion of developer mixture into said entry portion from said developer means, movement of said sampling portion through said tube and return of said sampling portion from said exit portion of said tube to said developer means, said mounting means further mounting said flow tube in a balanced condition representative of a desired weight of developer mixture as it flows through said tube, with the relationship being such that said tube moves between first and second conditions representative of higher and lower toner concentrations in said mixture; and means for sensing the status of said flow tube to control said toner dispensing means.

Claim 4

The apparatus of claim 2, further comprising: a pair of tie down means comprising separate means positioned a predetermined distance apart to accommodate at least the cross-sectional dimension of said flow tube therebetween; and pivot wire means interconnecting said flow tube and said tie down means with said flow tube positioned interMediate said pair of tie down means in a balanced sensing condition for monitoring of said sampling portion of developer mixture.

Claim 5

The system of claim 3, further comprising: sensing means comprising a magnet mounted on said flow tube and a reed switch operated by movement of said magnet to control said toner dispensing means.

Claim 6

The apparatus of claim 3, further comprising: means for adjusting said tie down means to establish a desired tension and balance relationship of said pivot wires and said flow tube.

Claim 7

The system of claim 3, wherein said: tie down means mounts said flow tube means above the point of tie down to establish a bistable action of said tube.

Claim 8

The system of claim 2, further comprising: a balance shaft mounting said flow tube means; a pair of bearings supporting said shaft to establish a balanced relationship of said flow tube means; means providing a resilient force on said balance shaft; and means for varying said resilient force to control the center of balance of said flow tube and thereby the degree of said sensitivity of said monitoring system.

Claim 9

The system of claim 7, further comprising: baffle means in said flow tube means to regulate the flow of mixture therethrough.

Claim 10

The system of claim 7, further comprising: a supply funnel connected to the entry portion of said flow tube for guiding developer mixture from said developer means to said flow tube during operation; and a screen positioned between said developer means and said flow tube for interception of developer mixture particles from said funnel to prevent entry of particles over a predetermined size into said flow tube.

Claim 11

The system of claim 7, further comprising: a return funnel positioned between the exit portion of said flow tube and said developer means; and baffle means in said return funnel to regulate flow of developer mixture therethrough.