MARKING SYSTEM WITH BYPASS TUBE
A marking system of a printer incorporates a bypass tube in its ink supply system to enable ink to bypass a pump during a drool process that removes air bubbles from a printhead. The bypass tube includes a valve that is opened during the drool operation and closed during normal operation of the marking system.
1 . A marking system, comprising:
a printhead comprising a plurality of nozzles configured to eject ink; and
a fluid supply system configured to supply the ink to the printhead, the fluid supply system comprising:
an ink pump fluidly connected to one or more conduit segments and configured to transport the ink toward the printhead via the one or more conduit segments,
a bypass tube fluidly coupled to an inlet of the ink pump and an outlet of the ink pump,
a valve that is connected to the bypass tube and configured to transport ink through the bypass tube when open, and not transport ink through the bypass tube when closed; and
a control system configured to:
open the valve to transport the ink through the bypass tube instead of the ink pump in response to detection of a missing nozzle condition in the printhead; and
allow the ink to drool through the nozzles of the printhead and absorb air bubbles as the ink drools.
2 . The marking system of claim 1 , further comprising, in the fluid supply system:
a degasser positioned to degas the ink before passing the ink to the ink pump;
an ink reservoir positioned to receive the ink from the ink pump and/or the bypass tube; and
a purge pump fluidly coupled to the ink reservoir and configured to provide pressure through the system during a purge protocol.
3 . The marking system of claim 2 , wherein the ink reservoir is below a buffer tank that is configured to store ink for the fluid supply system such that the ink will flow through the bypass tube via gravitational force when the valve is open.
4 . The marking system of claim 1 , wherein the ink pump comprises a peristaltic pump that is configured to draw the ink therethrough via vacuum pressure and act as a stop when not in use.
5 . The marking system of claim 1 , wherein the control system is electronically coupled to a sensor that is configured to detect whether the plurality of nozzles are operating properly.
6 . The marking system of claim 1 , wherein the missing nozzle condition comprises determining a number of missing nozzles of a document printed by the marking system and determining that the number of missing nozzles is greater than a threshold number of missing nozzles.
7 . The marking system of claim 1 , wherein the plurality of nozzles comprise piezoelectric elements that are configured to vibrate when the valve of the bypass tube is opened and pressure in the printhead is positive and above a threshold.
8 . The marking system of claim 7 , wherein the control system is configured to vibrate the piezoelectric elements by sending a voltage therethrough that is lower than a voltage sent therethrough during a printing operation.
9 . The marking system of claim 1 , further comprising a plurality of ink pumps that are configured to work with various ink colors, wherein each of the plurality of ink pumps is provided with a corresponding bypass tube.
10 . A method of removing gas from a printhead, the method comprising:
providing a marking system comprising:
a printhead,
a control system, and
a fluid supply system comprising:
an ink pump fluidly connected to one or more conduit segments and configured to transport the ink toward the printhead via the one or more conduit segments,
a bypass tube fluidly coupled to an inlet of the ink pump and an outlet of the ink pump, and
a valve that is connected to the bypass tube and configured to transport ink through the bypass tube when open, and not transport ink through the bypass tube when closed; and
by the control system, in response to the control system detecting a missing nozzle condition in the printhead or by receiving a command from an operator:
causing the valve to open, thus allowing the ink to pass through the bypass tube, and
allow the ink to drool through the nozzles of the printhead and absorb air bubbles as the ink drools.
11 . The method of claim 10 , wherein:
the plurality of nozzles comprise piezoelectric elements; and
allowing the ink to drool through the nozzles comprises causing the piezoelectric elements to vibrate in response to the control system detects that pressure within the printhead is positive and above a threshold.
12 . The method of claim 11 , wherein causing the piezoelectric elements to vibrate comprises applying a voltage to the piezoelectric elements that is lower than a voltage applied to the piezoelectric elements during a normal printing operation.
13 . The method of claim 11 , wherein the voltage applied when causing the piezoelectric elements to vibrate is a peak-to-peak voltage of approximately 10 volts to approximately 30 volts.
14 . The method of claim 10 , wherein the ink pump is positioned below a buffer tank configured to supply ink to the fluid supply system and the ink flows through the bypass tube by gravity when the valve is open.
15 . The method of claim 10 , wherein detecting the missing nozzle condition comprises detecting that at least a threshold amount of the plurality of nozzles are not operating properly.
16 . The method of claim 10 , wherein detecting the missing nozzle condition comprises measuring a number of missing nozzles on a document printed by the marking system and determining whether the number of missing nozzles meets a threshold number of missing nozzles.
17 . The method of claim 10 , wherein causing the valve to open comprises sending a message to an operator that a cycle of opening the valve should be completed.
18 . The method of claim 10 , further comprising, by the control system, reducing voltage to the plurality of nozzles.