Capacitive toner level sensor

1. A container for containing toner, comprising:

a first electrode;

a roller disposed within the container;

a doctor blade positioned in proximity to the roller for removing or smoothing at least a part of a toner layer on the roller, wherein the doctor blade forms a second electrode, the first and second electrodes forming a capacitor having a capacitance that changes in response to a change in an amount of toner existing in the container between the first and second electrodes;

a third electrode disposed in the container such that the first electrode is positioned between the second and third electrodes, the first and third electrodes forming a second capacitor having a capacitance that changes in response to a change in an amount of toner existing in the container between the first and third electrodes; and

a toner inlet for receiving toner, an auger disposed relative to the inlet for distributing toner within the container which passes through the inlet, and a gutter disposed beneath the auger, wherein the third electrode comprises the gutter.

2. The container of claim 1 , wherein the first electrode is disposed in a central portion of the container.

3. The container of claim 1 , wherein the second and third electrodes at least partly surround the first electrode so as to provide electrical shielding thereto.

4. The container of claim 1 , wherein at least a portion of the first electrode, the second electrode and the third electrode are disposed substantially in parallel with each other.

5. The container of claim 1 , wherein the first electrode includes a first portion and one or more finger members which extend from the first portion.

6. A container for holding toner, comprising:

a first electrode disposed within the container;

a second electrode electrically connected to the first electrode and disposed within the container opposite the first electrode; and

a sense electrode disposed between the first electrode and the second electrode, the sense electrode and the first electrode forming a first capacitor having a first capacitance that changes in response to a change in toner amount existing therebetween, and the sense electrode and the second electrode forming a second capacitor having a second capacitance that changes in response to a change in toner amount existing therebetween;

wherein the sense electrode includes a first portion and a plurality of finger members which extend from the first portion.

7. The container of claim 6 , wherein each finger member comprises a substantially inverted T-shaped finger.

8. The container of claim 6 , further comprising a movable toner agitator having one or more blades sized for passing through the plurality of finger members when the toner agitator is moved.

9. The container of claim 6 , further comprising a roller and a doctor blade positioned in proximity to the roller for removing or smoothing at least a part of a layer of toner on the roller, the doctor blade forming at least part of the second electrode.

10. The container of claim 6 , wherein the sense electrode is positioned substantially midway between the first and second electrodes.

11. The container of claim 6 , further comprising a toner inlet for receiving toner, an auger disposed relative to the inlet for distributing toner within the container that passes through the inlet, and a gutter disposed beneath the auger, wherein the first electrode comprises the gutter.

12. A container for holding toner, comprising:

a plurality of electrodes disposed within the container and including at least two first electrodes and at least one second electrode, the plurality of electrodes forming at least two capacitors having capacitances that change in response to a change in an amount of toner existing within the container;

wherein the at least one second electrode is positioned at a central portion within the container and the at least two first electrodes are positioned to at least partly surround the at least one second electrode so as to provide electrical shielding thereto; and

wherein the at least one second electrode has a plate portion and a plurality of finger members extending therefrom, the container further comprising a toner agitator having blades that, when the toner agitator is rotated, pass through spaces between adjacent fingers of the at least one second electrode.

13. The container of claim 12 , wherein each finger member comprises a substantially inverted T-shaped finger member.

14. The container of claim 12 , wherein each of the blades of the toner agitator is substantially T-shaped.

15. The container of claim 12 , further comprising a toner inlet, an auger disposed relative to the toner inlet for moving toner that passes through the toner inlet, and a gutter positioned beneath the auger within the container, the gutter forming at least part of one of the first electrodes.

16. The container of claim 12 , further comprising a roller disposed within the container and a doctor blade positioned in proximity to the roller for removing a part of a layer of toner on the roller, the doctor blade forming at least part of one of the first electrodes.

17. The container of claim 12 , wherein at least a portion of the first and second electrodes extend substantially parallel to each other.

18. A container for containing toner, comprising:

a first electrode;

a roller disposed within the container;

a doctor blade positioned in proximity to the roller for removing or smoothing at least a part of a toner layer on the roller, wherein the doctor blade forms a second electrode, the first and second electrodes forming a capacitor having a capacitance that changes in response to a change in an amount of toner existing in the container between the first and second electrodes; and

a toner inlet for receiving toner, an auger disposed relative to the inlet for distributing toner within the container that passes through the inlet, and a gutter disposed beneath the auger, wherein the first electrode comprises the gutter.

19. A container for holding toner, comprising:

a plurality of electrodes disposed within the container and including at least two first electrodes and at least one second electrode, the plurality of electrodes forming at least two capacitors having capacitances that change in response to a change in an amount of toner existing within the container;

wherein the at least one second electrode is positioned at a central portion within the toner container and the at least two first electrodes are positioned to at least partly surround the at least one second electrode so as to provide electrical shielding thereto; and

a toner inlet, an auger disposed relative to the toner inlet for moving toner that passes through the toner inlet, and a gutter positioned beneath the auger within the toner container, the gutter forming at least part of one of the first electrodes.