System and method for measuring a supply of solid ink in a solid ink printer

• US 20090128591A1
• Filed: 11/21/2007
• Published: 05/21/2009
• Est. Priority Date: 11/21/2007
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Fairchild, Michael Alan, Esplin, Ernest Isreal, Knierim, David L.
• Granted Patent: US 8,550,609 B2
• Time in Patent Office: Days
• US Class Current: 347/7
• CPC Class Codes: B41J 2/17593 Supplying ink in a solid state
• CPC Class Codes: B41J 2002/17579 Measuring electrical impedance for ink level indication

Abstract

A solid ink printer includes a solid ink measurement system that helps ensure an adequate supply of solid ink is in the feed channels delivering solid ink to a melting device within a printer. The solid ink measurement system includes a driving electrode mounted along a substantial length of a first structure of a first solid ink feed channel, a sensing electrode mounted along a substantial length of a second structure of the first solid ink feed channel, the sensing electrode being opposite and generally parallel to the driving electrode, an AC voltage source coupled to the driving electrode to generate an electrical field emitted from the driving electrode, and a capacitance measurement circuit coupled to the sensing electrode to receive an electrical signal induced in the sensing electrode by the electrical field generated by the driving electrode, the capacitance measurement circuit being configured to identify an amount of solid ink in the first feed channel that corresponds to the electrical signal received from the sensing electrode.

Claims

1. A solid ink measurement system comprising:

a driving electrode mounted along a substantial length of a first structure in a first solid ink feed channel;

a sensing electrode mounted along a substantial length of a second structure of the first solid ink feed channel, the sensing electrode being opposite and generally parallel to the driving electrode;

an AC voltage source coupled to the driving electrode to generate an electrical field emitted from the driving electrode; and

a capacitance measurement circuit coupled to the sensing electrode to receive an electrical signal induced in the sensing electrode by the electrical field generated by the driving electrode, the capacitance measurement circuit being configured to identify an amount of solid ink in the first feed channel that corresponds to the electrical signal received from the sensing electrode.

2. The solid ink measurement system of claim 1, the driving electrode and the sensing electrode being cylindrical electrical conductors.

3. The solid ink measurement system of claim 1, the driving electrode and the sensing electrode being planar electrical conductors.

4. The solid ink measurement system of claim 1, the driving electrode and the sensing electrode being electrically conductive grids.

5. The solid ink measurement system of claim 1, the AC voltage source providing a direct current (DC) component with an AC voltage.

6. The solid ink measurement system of claim 1 further comprising:

a second driving electrode mounted along a substantial length of a first structure of a second solid ink feed channel;

the sensing electrode being mounted in a feed channel wall that is common to the first feed channel and the second feed channel; and

a driving electrode selector for selectively coupling the first driving electrode and the second driving electrode to the AC voltage source to enable the sensing electrode to provide a first electrical signal to the capacitance measurement circuit to identify a solid ink amount in the first feed channel in response to the AC voltage source being coupled to the first driving electrode and to provide a second electrical signal to the capacitance measurement circuit to identify a solid ink amount in the second feed channel in response to the AC voltage source being coupled to the second driving electrode.

7. The system of claim 6, further comprising:

a third driving electrode mounted along a substantial length of a third solid ink feed channel;

a second sensing electrode being mounted in a wall between a feed channel structure that is common to the third feed channel and a fourth feed channel; and

the driving electrode selector selectively coupling the first driving electrode, the second driving electrode, and the third driving electrode to the AC voltage source to enable the sensing electrode to provide a first electrical signal from the first sensing electrode to the capacitance measurement circuit to identify a solid ink amount in the first feed channel and a second electrical signal from the second sensing electrode to the capacitance measurement circuit to identify a solid ink amount in the third feed channel in response to the AC voltage source being coupled to the first driving electrode and the third driving electrode, and to provide a third electrical signal from the first sensing electrode to the capacitance measurement circuit to identify a solid ink amount in the second feed channel and a fourth electrical signal from the second sensing electrode to the capacitance measurement circuit to identify a solid ink amount in the fourth feed channel in response to the AC voltage source being coupled to the second driving electrode.

8. A method for measuring solid ink in a solid ink printer comprising:

coupling an alternating current (AC) voltage source to a driving electrode mounted along a substantial length of a first structure of a first solid ink feed channel to emit an electric field from the driving electrode into the first solid ink feed channel;

generating an electrical signal in a first sensing electrode mounted along a substantial length of a second structure of the first solid ink feed channel that is opposite and generally parallel to the driving electrode, the electrical signal being generated in response to the electric field generated by the driving electrode; and

identifying an amount of solid ink in the first feed channel that corresponds to the electrical signal generated by the first sensing electrode.

9. The method of claim 8, the coupling of the AC voltage source further comprises:

providing a direct current (DC) component with an AC component to the driving electrode.

10. The method of claim 8 further comprising:

coupling the AC voltage source to a second driving electrode mounted along a substantial length of a first structure of a second solid ink feed channel to emit an electric field from the second driving electrode into the second solid ink feed channel, the coupling of the AC voltage source to the second driving electrode occurring during a time period in which the first driving electrode is not coupled to the AC voltage source;

generating a second electrical signal in the first sensing electrode mounted along a substantial length of the second structure of the first solid ink feed channel that is opposite and generally parallel to the second driving electrode, the second electrical signal being generated in response to the electric field generated by the second driving electrode; and

identifying a solid ink amount in the second feed channel that corresponds to the second electrical signal generated by the first sensing electrode, the first and the second driving electrodes being coupled to the AC voltage source in a mutually exclusive manner to generate the first and the second electrical signals with the first sensing electrode at different times for identification of the solid ink in the first and the second feed channels at different times.

11. The method of claim 10 further comprising:

coupling the AC voltage source to a third driving electrode mounted along a substantial length of a first structure of a third solid ink feed channel to emit an electric field from the third driving electrode into the second solid ink feed channel, the coupling of the AC voltage source to the third driving electrode occurring during a time period in which the first driving electrode is coupled to the AC voltage source and the second driving electrode is not coupled to the AC voltage source during the time period;

generating a third electrical signal in a second sensing electrode mounted along a substantial length of a second structure of a third solid ink feed channel that is opposite and generally parallel to the third driving electrode, the third electrical signal being generated in response to the electric field generated by the third driving electrode; and

identifying a solid ink amount in the third feed channel that corresponds to the third electrical signal generated by the second sensing electrode, the first and the third driving electrodes being coupled to the AC voltage source contemporaneously to generate the first and the third electrical signals with the first and the third sensing electrodes contemporaneously for identification of the solid ink in the first and the third feed channels.

12. The method of claim 11 further comprising:

coupling the AC voltage source to the second driving electrode to emit an electric field from the second driving electrode into the second solid ink feed channel and into a fourth solid ink feed channel, the coupling of the AC voltage source to the second driving electrode occurring during a time period in which the first and the third driving electrodes are not coupled to the AC voltage source;

generating a fourth electrical signal in the second sensing electrode while also generating the second electrical signal in the first sensing electrode, the fourth electrical signal being generated in response to the electric field generated by the second driving electrode; and

identifying a solid ink amount in a fourth feed channel that corresponds to the fourth electrical signal while identifying a solid ink amount in the second feed channel that corresponds to the second electrical signal generated by the sensing electrode, the first and the second driving electrodes being coupled to the AC voltage source in a mutually exclusive manner to generate the first and the second electrical signals with the first sensing electrode at different times and to generate the third and the fourth electrical signals with the second sensing electrode at different times for identification of an amount of solid ink in the first and the third feed channels at a time that is different than the time during which an amount is identified for the solid ink in the second and fourth feed channels.

13. An ink loader for a solid ink printer comprising:

a plurality of feed channels through which solid ink is delivered to a melting assembly;

a plurality of driving electrodes arranged in the feed channels;

a plurality of sensing electrodes arranged in the feed channels;

an alternating current (AC) voltage source for coupling electrical power to the driving electrodes to emit an electric field from the driving electrodes into the feed channels; and

a capacitance measurement circuit coupled to the plurality of sensing electrodes to receive electrical signals induced in the sensing electrodes by the electric fields generated by the driving electrodes, the capacitance measurement circuit being configured to identify an amount of solid ink in the feed channels that corresponds to the electrical signal received from the sensing electrode that is located across a feed channel from the driving electrode emitting the electric field inducing the electrical signal in the sensing electrode.

14. The ink loader of claim 13, the sensing electrodes being located in walls shared between independent feed channels.

15. The ink loader of claim 14, the driving electrodes being located in walls shared between independent feed channels;

a first driving electrode being located in an outside wall of a first feed channel; and

a last driving electrode being located in an outside wall of a last feed channel.

16. The ink loader of claim 13, the driving electrodes and the sensing electrodes being located in walls of the feed channels and the driving electrodes and the sensing electrodes being alternated in the walls of feed channels in a left to right sequence across the feed channels.

17. The ink loader of claim 13, the sensing electrodes being located in floors of the feed channels;

and

the driving electrodes being located in a cover over the feed channels.

18. The ink loader of claim 13 further comprising:

a driving electrode switch for selectively coupling the AC voltage source to a pair of driving electrodes to emit electric fields towards a sensing electrode shared by the pair of driving electrodes, the driving electrodes in the pair of driving electrodes being coupled to the AC voltage source at mutually exclusive times to generate two electrical signals with the shared sensing electrode, one electrical signal corresponding to an amount of solid ink in one feed channel and the other electrical signal corresponding to an amount of solid ink in the other feed channel.

19. The ink loader of claim 13, the AC voltage source also providing a direct current (DC) component to the driving electrodes.

20. The ink loader of claim 13, the driving electrodes and sensing electrodes being conductive strips.