1. An ink-jet printer comprising:
an ink circulation path comprising
an ink head having a nozzle face on which a plurality of nozzles are formed and discharging an ink from the nozzles in accordance with an image signal to perform a printing process on a recording medium;
a first tank disposed so that a liquid level of ink stored in the first tank is on a same level as, or higher than, the nozzle face of the ink head in a gravitational direction, and being able to communicate with an atmosphere or to be shut off from the atmosphere;
a second tank disposed so that a liquid level of ink stored in the second tank is lower than the nozzle face of the ink head in the gravitational direction, and being able to communicate with the atmosphere or to be shut off from the atmosphere; and
a pump sending the ink in the second tank to the first tank;
a pressure adjustment unit applying, when the second tank is shut off from the atmosphere, a negative pressure to the second tank,
wherein
the ink circulation path makes the first tank communicate with the atmosphere and shuts off the second tank from the atmosphere in an ink-circulation state period in which the ink is circulated, and shuts off the first tank from the atmosphere and makes the second tank communicate with the atmosphere in a no ink-circulation state period in which the ink is not circulated; and
during the printing process, the ink-circulation state and the no ink-circulation state are switched.
2. The ink-jet printer according to claim 1, wherein the switching between the ink-circulation state and the no ink-circulation state is performed when air bubbles in the ink circulation path need to be removed, or when a temperature of the ink deviates from a desired temperature range, or when a preset given time has passed.
3. The ink-jet printer according to claim 1, wherein
the ink circulation path is configured so that a pressure applied to the ink head in the ink-circulation state period and a pressure applied to the ink head in the no ink-circulation state period are within a range of pressures in the ink head with which printing can be performed.
4. The ink-jet printer according to claim 2, wherein
the ink circulation path is configured so that a pressure applied to the ink head in the ink-circulation state period and a pressure applied to the ink head in the no ink-circulation state period are within a range of pressures in the ink head with which printing can be performed.
5. The ink-jet printer according to claim 3, wherein
the pressure applied to the ink head in the no ink-circulation state period is determined by a negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face; and
the pressure applied to the ink head in the ink-circulation state period is determined by a positive pressure generated by a difference in height between the liquid level of the first tank and the nozzle face, the negative pressure generated by the difference in height between the liquid level of the second tank and the nozzle face, the negative pressure applied by the pressure adjustment unit, a flow path resistance from the first tank to the ink head, and a flow path resistance from the ink head to the second tank.
6. The ink-jet printer according to claim 4, wherein
the pressure applied to the ink head in the no ink-circulation state period is determined by a negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face; and
the pressure applied to the ink head in the ink-circulation state period is determined by a positive pressure generated by a difference in height between the liquid level of the first tank and the nozzle face, the negative pressure generated by the difference in height between the liquid level of the second tank and the nozzle face, the negative pressure applied by the pressure adjustment unit, a flow path resistance from the first tank to the ink head, and a flow path resistance from the ink head to the second tank.
7. The ink-jet printer according to claim 1, wherein the negative pressure applied by the pressure adjustment unit in the ink-circulation state period is larger than a negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face.
8. The ink-jet, printer according to claim 5, wherein the negative pressure applied by the pressure adjustment unit in the ink-circulation state period is larger than the negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face.
9. The ink-jet printer according to claim 6, wherein the negative pressure applied by the pressure adjustment unit in the ink-circulation state period is larger than the negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face.
10. The ink-jet printer according to claim 1, wherein assuming
a water head differential pressure being a positive pressure generated by a difference in height between the liquid level of the first tank and the nozzle face as P1;
a water head differential pressure being a negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face as P2;
a pressure being the negative pressure applied to the second tank by the pressure adjustment unit as P3;
a flow path resistance from the first tank to the ink head as R1; and
a flow path resistance from the ink head to the second tank as R2,
the ink circulation path is configured to satisfy
\u2212(P3(P1\u2212P2))=R2R1.
11. The ink-jet printer according to claim 5, wherein assuming
a water head differential pressure being the positive pressure generated by the difference in height between the liquid level of the first tank and the nozzle face as P1;
a water head differential pressure being the negative pressure generated by the difference in height between the liquid level of the second tank and the nozzle face as P2;
a pressure being the negative pressure applied to the second tank by the pressure adjustment unit as P3;
the flow path resistance from the first tank to the ink head as R1; and
the flow path resistance from the ink head to the second tank as R2,
the ink circulation path is configured to satisfy
\u2212(P3(P1\u2212P2))=R2R1.
12. The ink-jet printer according to claim 6, wherein assuming
a water head differential pressure being the positive pressure generated by the difference in height between the liquid level of the first tank and the nozzle face as P1;
a water head differential pressure being the negative pressure generated by the difference in height between the liquid level of the second tank and the nozzle face as P2;
a pressure being the negative pressure applied to the second tank by the pressure adjustment unit as P3;
the flow path resistance from the first tank to the ink head as R1; and
the flow path resistance from the ink head to the second tank as R2,
the ink circulation path is configured to satisfy
\u2212(P3(P1\u2212P2))=R2R1.
13. An ink-jet printer comprising:
an ink circulation path comprising
an ink head having a nozzle face on which a plurality of nozzles are formed and discharging an ink from the nozzles in accordance with an image signal to perform a printing process on a recording medium;
a first tank disposed so that a liquid level of ink stored in the first tank is lower than the nozzle face of the ink head in a gravitational direction, and being able to communicate with an atmosphere or to be shut off from the atmosphere;
a second tank disposed so that a liquid level of ink stored in the second tank is lower than the nozzle face of the ink head in the gravitational direction, and being able to communicate with the atmosphere or to be shut off from the atmosphere; and
a pump sending the ink in the second tank to the first tank;
a pressure application unit applying, when the first tank is shut off from the atmosphere, a positive pressure to an inside of the first tank; and
a pressure adjustment unit applying, when the second tank is shut off from the atmosphere, a negative pressure to the second tank,
wherein
the ink circulation path shuts off the first tank from the atmosphere and shuts off the second tank from the atmosphere in an ink-circulation state period in which the ink is circulated, and shuts off the first tank from the atmosphere and makes the second tank communicate with the atmosphere in a no ink-circulation state period in which the ink is not circulated; and
during the printing process, the ink-circulation state and the no ink-circulation state are switched.
14. The ink-jet printer according to claim 13, wherein the switching between the ink-circulation state and the no ink-circulation state is performed when air bubbles in the ink circulation path need to be removed, or when a temperature of the ink deviates from a desired temperature range, or when a preset given time has passed.
15. The ink-jet printer according to claim 13, wherein
the ink circulation path is configured so that a pressure applied to the ink head in the ink-circulation state period and a pressure applied to the ink head in the no ink-circulation state period are within a range of pressures in the ink head with which printing can be performed.
16. The ink-jet printer according to claim 15, wherein
the pressure applied to the ink head in the no ink-circulation state period is determined by a negative pressure generated by a difference in height between the liquid level of the second tank and the nozzle face; and
the pressure applied to the ink head in the ink-circulation state period is determined by the positive pressure applied by the pressure application unit, a negative pressure generated by a difference in height between the liquid level of the first tank and the nozzle face, the negative pressure generated by the difference in height between the liquid level of the second tank and the nozzle face, the negative pressure applied by the pressure adjustment unit, a flow path resistance from the first tank to the ink head, and a flow path resistance from the ink head to the second tank.
17. The ink-jet printer according to claim 16, wherein assuming
a pressure being the positive pressure applied to the first tank by the pressure application unit as P0;
a water head differential pressure being the negative pressure generated by the difference in height between the liquid level of the first tank and the nozzle face as P1;
a water head differential pressure being the negative pressure generated by the difference in height between the liquid level of the second tank and the nozzle face as P2;
a pressure being the negative pressure applied to the second tank by the pressure adjustment unit as P3;
the flow path resistance from the first tank to the ink head as R1; and
the flow path resistance from the ink head to the second tank as R2,
the ink circulation path is configured to satisfy
\u2212(P3(P0+P1\u2212P2))=R2R1.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method comprising:
a) receiving at a first vehicle a ground signal and state information from another vehicle;
b) if altitude of the first vehicle is below a threshold value, predicting at the first vehicle locations of the first vehicle and the other vehicle for two or more future times;
c) outputting a warning alert, if distance between at least one of a pair of the predicted locations is below a threshold distance and the corresponding future time if below a first time threshold; and
d) outputting a caution alert, if distance between at least one of a pair of the predicted locations is below the threshold distance and the corresponding future time is between the first time threshold and a second time threshold.
2. The method of claim 1, further comprising repeating b-d) after a predefined delay, if distance between at least one of a pair of the predicted locations is not below the threshold distance.
3. The method of claim 2, further comprising repeating c-d) after a predefined delay, if distance between at least one of a pair of the predicted locations is below the threshold distance and the corresponding future time is not below the first time threshold and not between the first time threshold and a second time threshold.
4. The method of claim 1, wherein predicting comprises determining an acceleration value for the other vehicle and predicting according to the determined acceleration value.
5. The method of claim 1, wherein predicting comprises determining an acceleration value for the first vehicle and predicting according to the determined acceleration value.
6. The method of claim 1, wherein predicting comprises determining a track-angle rate based on track-angle data of the first vehicle and track-angle data received from the other vehicle and predicting according to the determined track-angle rate.
7. The method of claim 1, further comprising:
determining at the first vehicle relative direction from which the other vehicle is converging; and
outputting a traffic location message based on the convergence determination.
8. The method of claim 7, wherein the outputted traffic location message is outputted with the warning and caution alerts.
9. A system on a vehicle comprising:
a receiver configured to receive a ground signal and state information from another vehicle;
an output device; and
a processor in signal communication with the receiver and the output device, the processor comprising:
a first component configured to predict at the first vehicle locations of the first vehicle and the other vehicle for two or more future times, if altitude of the first vehicle is below a threshold value;
a second component configured to send a warning alert to the output device, if distance between at least one of a pair of the predicted locations is below a threshold distance and the corresponding future time if below a first time threshold; and
a third component configured to send a caution alert to the output device, if distance between at least one of a pair of the predicted locations is below the threshold distance and the corresponding future time is between the first time threshold and a second time threshold.
10. The system of claim 9, wherein the first-third components repeat after a predefined delay if distance between at least one of a pair of the predicted locations is not below the threshold distance.
11. The system of claim 10, wherein the second and third components repeat after a predefined delay, if distance between at least one of a pair of the predicted locations is below the threshold distance and the corresponding future time is not below the first time threshold and not between the first time threshold and a second time threshold.
12. The system of claim 9, wherein the first component determines an acceleration value for the other vehicle and predicts according to the determined acceleration value.
13. The system of claim 9, wherein the first component determines an acceleration value for the first vehicle and predicts according to the determined acceleration value.
14. The system of claim 9, wherein the first component determines a track-angle rate based on track-angle data of the first vehicle and track-angle data received from the other vehicle and predicts according to the determined track-angle rate.
15. The system of claim 9, wherein the processor further comprises:
a fourth component configured to determine at the first vehicle relative direction from which the other vehicle is converging; and
a fifth component configured to output a traffic location message to the output device based on the convergence determination.
16. The system of claim 15, wherein the output device outputs the traffic location message with the warning and caution alerts.
17. A system comprising:
a means for receiving at a first vehicle a ground signal and state information from another vehicle;
a means for predicting at the first vehicle locations of the first vehicle and the other vehicle for two or more future times, if altitude of the first vehicle is below a threshold value;
a means for outputting a warning alert, if distance between at least one of a pair of the predicted locations is below a threshold distance and the corresponding future time if below a first time threshold; and
a means for outputting a caution alert, if distance between at least one of a pair of the predicted locations is below the threshold distance and the corresponding future time is between the first time threshold and a second time threshold.