Print dryer heater control
First Claim
1. A printer, comprising:
- a print dryer having a variable-power heater controllable by a duty cycle;
a sensor in the print dryer to repetitively measure and record an internal temperature of the print dryer; and
a controller coupled to the heater and the sensor toapply to the heater a high duty cycle to heat the print dryer until the internal temperature exceeds a target temperature and then apply a low duty cycle,calculate from the recorded internal temperatures a dT/dt slope occurring at an end portion of the high duty cycle before the low duty cycle,convert the dT/dt slope into an initial heater duty cycle according to a piecewise-continuous function associated with the target temperature, where the initial heater duty cycle is negatively proportional to the dT/dt slope below a given value of dT/dt slope and constant above the given value of dT/dt slope, andperform proportional-integral-derivative (PID) control of the heater beginning at the initial heater duty cycle to maintain the print dryer at the target temperature within a predefined accuracy.
1 Assignment
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Accused Products
Abstract
In one example, a method for controlling temperature of a print dryer. High power is applied to a heater of the print dryer. A series of temperatures of the print dryer are periodically measured and stored until a target temperature for the print dryer is exceeded. Low power is applied to the heater after the target temperature is exceeded. A rate of temperature change at a time when the target temperature was exceeded is calculated from the stored temperatures. Using the rate, an initial heater duty cycle defining an initial heater power determined. PID control of the heater power is performed, beginning with the initial heater duty cycle, to maintain the print dryer temperature at the target temperature within a predefined accuracy.
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Citations
15 Claims
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1. A printer, comprising:
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a print dryer having a variable-power heater controllable by a duty cycle; a sensor in the print dryer to repetitively measure and record an internal temperature of the print dryer; and a controller coupled to the heater and the sensor to apply to the heater a high duty cycle to heat the print dryer until the internal temperature exceeds a target temperature and then apply a low duty cycle, calculate from the recorded internal temperatures a dT/dt slope occurring at an end portion of the high duty cycle before the low duty cycle, convert the dT/dt slope into an initial heater duty cycle according to a piecewise-continuous function associated with the target temperature, where the initial heater duty cycle is negatively proportional to the dT/dt slope below a given value of dT/dt slope and constant above the given value of dT/dt slope, and perform proportional-integral-derivative (PID) control of the heater beginning at the initial heater duty cycle to maintain the print dryer at the target temperature within a predefined accuracy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for controlling temperature of a print dryer, comprising:
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repetitively measuring and recording an internal temperature of the print dryer; applying to a variable-power heater of the print dryer a high duty cycle to heat the print dryer until the internal temperature exceeds a target temperature and then applying a low duty cycle; calculating from the recorded internal temperatures a dT/dt slope occurring at an end portion of the high duty cycle before the low duty cycle; converting the dT/dt slope into an initial heater duty cycle according to a piecewise-continuous function associated with the target temperature, where the initial heater duty cycle is negatively proportional to the dT/dt slope below a given value of dT/dt slope and constant above the given value of dT/dt slope; and performing proportional-integral-derivative (PID) control of the heater beginning at the initial heater duty cycle to maintain the print dryer at the target temperature within a predefined accuracy. - View Dependent Claims (12, 13, 14, 15)
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Specification