Ink jet printer with control
First Claim
1. An ink jet printer comprising:
- jet-forming means;
an ink system operable to provide ink to the jet-forming means; and
control means which control the operation of the ink system, the control means controlling the ink system to perform a predetermined sequence of operations in response to a predetermined input condition of the control means,wherein said predetermined input condition indicates that the jet-forming means has failed to form a normal ink jet, and said predetermined sequence comprises supplying suction pressure to the jet-forming means, the suction pressure tending to reverse the direction of the jet, so as to suck a fluid into the jet-forming means through an orifice through which ink forming the ink jet flows out of the jet-forming means when a normal ink jet is formed.
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Accused Products
Abstract
An ink jet printer automatically adjusts the amplitude of the modulation signal applied to a transducer (159) to break the ink jet into droplets. Correct modulation amplitude is determined from changes in jet break-up length, as determined by changes in jet break-up length, as determined by changes in jet break-up phase relative to the modulation signal.
The printer has interchangeable print heads (3), which may have different nozzle sizes. A calibration code, specifying the particular values of ink pressure, jet velocity and charge correction required for optimum performance of a particular print head (3), may be entered into control logic (93), which operates the printer accordingly.
Most print head components are mounted on a mounting subtract (111), with all connections being made to the underside of the mounting subtract (111) and sealed with a potting compound, to avoid damage.
Ink viscosity is controlled in response to ink pressure, which is in turn controlled in response to ink jet velocity. Thus all three parameters are maintained without the need for a viscosity meter. Ink jet velocity is sensed from signals induced by charged drops on spaced apart sensors (89, 91), the outputs from which are wired together and fed to a common comparator (105), which simplifies construction.
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Citations
13 Claims
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1. An ink jet printer comprising:
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jet-forming means; an ink system operable to provide ink to the jet-forming means; and control means which control the operation of the ink system, the control means controlling the ink system to perform a predetermined sequence of operations in response to a predetermined input condition of the control means, wherein said predetermined input condition indicates that the jet-forming means has failed to form a normal ink jet, and said predetermined sequence comprises supplying suction pressure to the jet-forming means, the suction pressure tending to reverse the direction of the jet, so as to suck a fluid into the jet-forming means through an orifice through which ink forming the ink jet flows out of the jet-forming means when a normal ink jet is formed. - View Dependent Claims (2, 3, 4, 5)
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6. An ink jet printer comprising:
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jet-forming means for forming a jet of ink; an ink system operable to provide ink to the jet-forming means; a charging electrode adjacent the jet-forming means; signal applying means to apply a charging signal to the charging electrode; and control means for responding to an input start signal to perform a start-up sequence, said start-up sequence comprising (i) controlling the ink system to pressurize the ink to a relatively high pressure for a first interval and to switch from withholding the ink from the jet-forming means to providing the ink to the jet-forming means when pressurizing the ink to the relatively high pressure to start the jet, and to pressurize the ink subsequently to a lower pressure and to provide the ink at the lower pressure to the jet-forming means to maintain the jet, and (ii) controlling the signal applying means to adjust the phase of said charging signal while the ink system is providing ink at said lower pressure. - View Dependent Claims (7, 8, 9, 10)
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11. An ink jet printer comprising:
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jet-forming means for forming a jet of ink; an ink system operable to provide ink to the jet-forming means; suction means for applying suction to the jet-forming means, the suction tending to reverse the direction of the jet; and control means for responding to an input stop signal by (i) controlling the ink system to cease to provide ink to the jet-forming means and (ii) controlling the suction means to apply the suction to the jet-forming means substantially simultaneously with the ink system ceasing to provide ink. - View Dependent Claims (12)
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13. A method of stopping a jet of an ink jet printer in response to an input stop signal, said method comprising conducting automatically under the control of a control means of the ink jet printer the steps of:
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ceasing to supply ink to a jet-forming means of the ink jet printer; and substantially simultaneously with said ceasing to supply, applying suction to the jet-forming means, the suction tending to reverse the direction of the jet.
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Specification