Temperature control apparatus, processing apparatus, and temperature control method

• US 20080234875A1
• Filed: 03/14/2008
• Published: 09/25/2008
• Est. Priority Date: 03/22/2007
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Nomura, Masatoshi
• Granted Patent: US 8,219,260 B2
• Time in Patent Office: Days
• US Class Current: 700/300
• CPC Class Codes: G05D 23/2401 using a heating element as a sensing element

Abstract

Disclosed is a temperature control apparatus including: a resistance heater to have a characteristic such that a resistance value of the resistance heater changes dependently on a temperature thereof; a signal generator to output a control signal having two voltage levels of an on-voltage and an second-voltage; a switching section to flow a first current through the resistance heater when the voltage level of the control signal is the first-voltage, and to flow a second current having a current value smaller than that of the first current through the resistance heater when the voltage level of the control signal is the second-voltage; and a voltage measuring instrument to measure a voltage value across the resistance heater at the time when the second current flows through the resistance heater, wherein the signal generator controls the temperature of the resistance heater based on the voltage value measured by the voltage measuring instrument.

Claims

1. A temperature control apparatus comprising:

a resistance heater to have characteristics such that a resistance value of the resistance heater changes dependently on a temperature thereof;

a signal generator to output a control signal having two voltage levels of a first-voltage and a second-voltage;

a switching section to flow a first current through the resistance heater when the voltage level of the control signal is the first-voltage, and to flow a second current having a current value smaller than that of the first current through the resistance heater when the voltage level of the control signal is the second-voltage; and

a voltage measuring instrument to measure a voltage value across the resistance heater at the time when the second current flows through the resistance heater, wherein

the signal generator controls the temperature of the resistance heater based on the voltage value measured by the voltage measuring instrument.

2. The temperature control apparatus according to claim 1, wherein

a voltage across the resistance heater is not applied to the voltage measuring instrument when the voltage level of the control signal is the first-voltage, and the voltage across the resistance heater is applied to the voltage measuring instrument when the voltage level of the control signal is the second-voltage, so that the voltage measuring instrument measures the voltage value across the resistance heater at the time when the second current flows through the resistance heater.

3. The temperature control apparatus according to claim 1, further comprising:

an adder to add a constant superimposing voltage to the control signal output from the signal generator to output, to the switching section, a signal obtained by adding the constant superimposing voltage to the control signal.

4. The temperature control apparatus according to claim 1, wherein:

the control signal is a pulse signal including the two voltage levels of the first-voltage and the second-voltage; and

the signal generator is a PWM controller equipped with a function of controlling a value of a duty ratio, which is a ratio between a time of the first-voltage of the control signal and a time of the second-voltage thereof.

5. The temperature control apparatus according to claim 4, wherein

the signal generator derives the temperature of the resistance heater on a basis of the voltage value measured by the voltage measuring instrument, and changes and re-sets the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature.

6. The temperature control apparatus according to claim 4, further comprising:

a current measuring instrument to measure a current value of a current flowing through the resistance heater; and

a resistance measuring instrument to measure the resistance value of the resistance heater on a basis of the voltage value measured by the voltage measuring instrument and the current value measured by the current measuring instrument, wherein

on a basis of the resistance value measured by the resistance measuring instrument and the resistance value of the resistance heater at a desired set temperature the signal generator changes and re-sets the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to the set temperature.

7. The temperature control apparatus according to claim 4, further comprising a constant current circuit to generate a constant current corresponding to the second current, wherein:

the switching section flows the constant current generated by the constant current circuit through the resistance heater when the voltage level of the control signal is the second-voltage, and

the signal generator changes and re-sets the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature on a basis of the voltage value measured by the voltage measuring instrument and a current value of the constant current.

8. A processing apparatus, supplied a raw material, subjected to temperature control thereof, causing a reaction or a phase change of the raw material, the apparatus comprising:

a processing device to cause the reaction or the phase change of the raw material; and

a temperature control apparatus including;

a resistance heater, provided in the processing device to heat the processing device, to have characteristics such that a resistance value of the resistance heater changes dependently on a temperature thereof;

a signal generator to output a control signal having two voltage levels of a first-voltage and a second-voltage;

a switching section to flow a first current through the resistance heater when the voltage level of the control signal is the first-voltage, and to flow a second current having a current value smaller than that of the first current through the resistance heater when the voltage level of the control signal is the second-voltage; and

a voltage measuring instrument to measure a voltage value across the resistance heater at the time when the second current flows through the resistance heater, wherein

the signal generator controls the temperature of the resistance heater based on the voltage value measured by the voltage measuring instrument.

9. The processing apparatus according to claim 8, wherein:

the raw material is a liquid;

the processing device is a vaporizer to heat the raw material to vaporize it; and

the signal generator controls the temperature of the resistance heater so as to be brought close to a temperature suitable for the vaporization of the raw material.

10. The processing apparatus according to claim 8, wherein:

the raw material is a mixture gas produce by vaporizing water and a liquid fuel including hydrogen in its composition;

the processing device is a reformer to produce a gas including the hydrogen by causing a reforming reaction of the raw material; and

the signal generator controls the temperature of the resistance heater so as to be brought close to a temperature suitable for causing the reforming reaction.

11. The processing apparatus according to claim 8, further comprising a combustor, supplied burning gas and oxygen, to produce combustion heat caused by a catalyst reaction to heat the processing device.

12. The processing apparatus according to claim 8, wherein a voltage across the resistance heater is not applied to the voltage measuring instrument in the temperature control apparatus when the voltage level of the control signal is the first-voltage, and the voltage across the resistance heater is applied to the voltage measuring instrument when the voltage level of the control signal is the second-voltage, so that the voltage measuring instrument measures the voltage value across the resistance heater at the time when the second current flows through the resistance heater.

13. The processing apparatus according to claim 8, wherein the temperature control apparatus further comprising an adder to add a constant superimposing voltage to the control signal output from the signal generator to output, to the switching section, a signal obtained by adding the superimposing voltage to the control signal.

14. The processing apparatus according to claim 8, wherein:

the control signal in the temperature control apparatus is a pulse signal including the two voltage levels of the first-voltage and the second-voltage; and

the signal generator is a PWM controller equipped with a function of controlling a value of a duty ratio, which is a ratio between a time of the first-voltage of the control signal and a time of the second-voltage thereof.

15. The processing apparatus according to claim 14, wherein the signal generator in the temperature control apparatus derives the temperature of the resistance heater on a basis of the voltage value measured by the voltage measuring instrument, and changes and re-sets the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature.

16. The processing apparatus according to claim 14, wherein:

the temperature control apparatus further comprises;

a current measuring instrument to measure a current value of a current flowing through the resistance heater; and

a resistance measuring instrument to measure the resistance value of the resistance heater on a basis of the voltage value measured by the voltage measuring instrument and the current value measured by the current measuring instrument, and wherein

on a basis of the resistance value measured by the resistance measuring instrument and the resistance value of the resistance heater at a desired set temperature the signal generator changes and re-sets the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to the set temperature.

17. The processing apparatus according to claim 14, wherein:

the temperature control apparatus further comprising a constant current circuit to generate a constant current corresponding to the second current;

the switching section flows the constant current generated by the constant current circuit through the resistance heater when the voltage level of the control signal is the second-voltage; and

the signal generator changes and re-sets the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature on a basis of the voltage value measured by the voltage measuring instrument and a current value of the constant current.

18. A temperature control method for controlling a temperature of a resistance heater having characteristics such that a resistance value of the resistance heater changes dependently on the temperature, the method comprising the steps of:

outputting a control signal having two voltage levels of a first-voltage and a second-voltage;

flowing a first current through the resistance heater when the voltage level of the control signal is the first-voltage, and flowing a second current having a current value smaller than that of the first current through the resistance heater when the voltage level of the control signal is the second-voltage;

measuring a voltage value across the resistance heater at the time when the second current flows through the resistance heater; and

controlling the control signal to control the temperature of the resistance heater on a basis of the voltage value measured at the step of measuring the voltage value.

19. The temperature control method according to claim 18, wherein:

the control signal is a pulse signal including the two voltage levels of the first-voltage and the second-voltage; and

the step of controlling the control signal includes a step of controlling a value of a duty ratio, which is a ratio between a time of the first-voltage of the control signal and a time of the second-voltage thereof.

20. The temperature control method according to claim 19, wherein the step of controlling the control signal includes a step of, on a basis of the temperature of the resistance heater obtained on a basis of the voltage value of the resistance heater measured at the step of measuring the voltage value, and a desired set temperature, changing the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to the set temperature, and re-setting the value.

21. The temperature control method according to claim 19, further comprising the steps of:

measuring a current value of a current flowing through the resistance heater; and

measuring the resistance value of the resistance heater on a basis of the voltage value measured at the step of measuring the voltage value and the current value measured at the step of measuring the current value, wherein

the step of controlling the control signal includes a step of changing the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature on a basis of the resistance value measured at the step of measuring the resistance value and the resistance value of the resistance heater at the set temperature, and re-setting the value.

22. The temperature control method according to claim 19, further comprising a step of generating a constant current corresponding to the second current to flow the constant current through the resistance heater when the control signal is the second-voltage, wherein

the step of controlling the control signal includes a step of changing the value of the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature on a basis of the voltage value measured at the step of measuring the voltage value and a current value of the constant current, and re-setting the value.

23. A temperature control method controlling a temperature of a resistance heater having characteristics such that a resistance value of the resistance heater changes dependently on the temperature, the method comprising the steps of:

outputting a control signal having two voltage levels of a first-voltage and a second-voltage;

flowing a first current through the resistance heater when the voltage level of the control signal is the first-voltage, and flowing a second current having a current value smaller than that of the first current through the resistance heater when the voltage level of the control signal is the second-voltage;

measuring a voltage value across the resistance heater at the time when the second current flows through the resistance heater, and measuring the resistance value of the resistance heater on a basis of the measured voltage value and the current value of the second current; and

controlling the control signal to control the temperature of the resistance heater on a basis of the resistance value measured at the step of measuring the resistance value.

24. The temperature control method according to claim 23, wherein:

the control signal is a pulse signal including the two voltage levels of the first-voltage and the second-voltage; and

the step of controlling the control signal includes a step of controlling a value of a duty ratio, which is a ratio between a time of the first-voltage and a time of the second-voltage.

25. The temperature control method according to claim 24, wherein the step of controlling the control signal includes a step of changing the duty ratio of the control signal so that the temperature of the resistance heater is brought close to a desired set temperature on a basis of the resistance value of the resistance heater measured at the step of measuring the resistance value and the resistance value of the resistance heater at the set temperature.