Heater energization control circuit, heater energization control method, and image forming apparatus

• US 20030136777A1
• Filed: 01/16/2003
• Published: 07/24/2003
• Est. Priority Date: 01/22/2002
• Status: Active Grant

• Current Assignee: Murata Machinery Limited (Muratec)
• Original Assignee: Murata Machinery Limited (Muratec)
• Inventors: Okubo, Seino
• Granted Patent: US 6,794,619 B2
• Time in Patent Office: Days
• US Class Current: 219/492
• CPC Class Codes: G03G 15/2003 using heat
• CPC Class Codes: H05B 1/0241 For photocopiers
• CPC Class Codes: Y10S 323/908 Inrush current limiters

Abstract

A heater energization control circuit includes a heater, a power source that supplies an alternating current to the heater, a first capacitor that charges and discharges in accordance with a first time constant that is determined by an electrostatic capacity of the first capacitor and a resistance value of a first resistor, and a second capacitor that charges and discharges in accordance with a second time constant that is determined by an electrostatic capacity of the second capacitor and a resistance value of a second resistor. A controller determines an energization start timing to the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor, and starting to supply the alternating current to the heater by the power source for supplying under this timing.

Claims

1. A heater energization control circuit comprising:

means for supplying an alternating current to a heater;

a first capacitor that charges and discharges in accordance with a first time constant that is determined by an electrostatic capacity of the first capacitor and a resistance value of a first resistor;

a second capacitor that charges and discharges in accordance with a second time constant that is determined by an electrostatic capacity of the second capacitor and a resistance value of a second resistor; and

means for determining an energization start timing to the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor, and starting to supply the alternating current to the heater by the means for supplying under this timing.

2. The heater energization control circuit according to claim 1, wherein the means for determining starts an energization to the heater when the voltage of the second capacitor becomes larger than the voltage of the first capacitor.

3. The heater energization control circuit according to claim 1, wherein the means for determining determines a period to energize the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor.

4. The heater energization control circuit according to claim 1, wherein the means for determining energizes the heater during a period when the voltage of the second capacitor is larger than the voltage of the first capacitor.

5. The heater energization control circuit according to claim 1, wherein the means for determining is a comparator, and the voltage of the first capacitor is input to a non-inverting input terminal of the comparator and voltage of the second capacitor is input to an inverting input terminal.

6. The heater energization control circuit according to claim 1, further comprising means for detecting a zero crossing of the alternating current, and the first capacitor is discharged at a time of a zero crossing, and the first capacitor is charged at a time of a non-zero crossing.

7. The heater energization control circuit according to claim 1, wherein the second capacitor is charged when a power switch is on, and the second capacitor is discharged when the power switch is off.

8. The heater energization control circuit according to claim 1, wherein at least one of the first capacitor and the second capacitor is a variable capacitor.

9. The heater energization control circuit according to claim 1, wherein at least one of the first resistor and the second resistor is a variable resistor.

10. A heater energization control method comprising:

determining an energization start timing to a heater in accordance with a size relationship between a voltage of a first capacitor and a voltage of a second capacitor; and

starting to supply an alternating current to the heater under the timing determined.

11. The heater energization control method according to claim 10, further comprising energizing to the heater when the voltage of the second capacitor becomes larger than the voltage of the first capacitor.

12. The heater energization control method according to claim 10, further comprising determining a period to energize the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor.

13. The heater energization control method according to claim 10, further comprising energizing the heater during a period when the voltage of the second capacitor is larger than the voltage of the first capacitor.

14. The heater energization control method according to claim 10, further comprising detecting a zero crossing of the alternating current, discharging the first capacitor at a time of a zero crossing, and charging the first capacitor at a time of a non-zero crossing.

15. The heater energization control method according to claim 10, further comprising charging the second capacitor when the power switch is on, and discharging the second capacitor when the power switch is off.

16. The heater energization control method according to claim 10, further comprising providing at least one of the first capacitor and the second capacitor as a variable capacitor.

17. The heater energization control method according to claim 10, further comprising providing at least one of the first resistor and the second resistor is a variable resistor.

18. An image forming apparatus comprising:

a heat fuser having a heater;

means for supplying an alternating current to the heater;

a first capacitor that charges and discharges in accordance with a first time constant that is determined by an electrostatic capacity of the first capacitor and a resistance value of a first resistor;

a second capacitor that charges and discharges in accordance with a second time constant that is determined by an electrostatic capacity of the second capacitor and a resistance value of a second resistor; and

means for determining an energization start timing to the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor, and starting to supply an alternating current to the heater by the means for supplying under this timing.

19. The image forming apparatus according to claim 18, wherein the means for determining starts an energization to the heater when the voltage of the second capacitor becomes larger than the voltage of the first capacitor.

20. The image forming apparatus according to claim 18, wherein the means for determining determines a period to energize the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor.

21. The image forming apparatus according to claim 18, wherein the means for determining energizes the heater during a period when the voltage of the second capacitor is larger than the voltage of the first capacitor.

22. The image forming apparatus according to claim 18, wherein the means for determining is a comparator, and the voltage of the first capacitor is input to a non-inverting input terminal of the comparator and the voltage of the second capacitor is input to an inverting input terminal.

23. The image forming apparatus according to claim 18, further comprising means for detecting a zero crossing of an alternating current, and the first capacitor is discharged at a time of a zero crossing, and the first capacitor is charged at a time of a non-zero crossing.

24. The image forming apparatus according to claim 18, further comprising a power switch, and the second capacitor is charged when the power switch is on, and the second capacitor is discharged when the power switch is off.

25. The image forming apparatus according to claim 18, wherein at least one of the first capacitor and the second capacitor is a variable capacitor.

26. The image forming apparatus according to claim 18, wherein at least one of the first resistor and the second resistor is a variable resistor.

27. A heater energization control circuit comprising:

means for supplying an alternating current to a heater;

a first capacitor that charges and discharges in accordance with a first time constant that is determined by an electrostatic capacity of the first capacitor and a resistance value of a first resistor;

a second capacitor that charges and discharges in accordance with a second time constant that is determined by an electrostatic capacity of the second capacitor and a resistance value of a second resistor; and

a controller that determines an energization start timing to the heater in accordance with a size relationship between a voltage of the first capacitor and a voltage of the second capacitor, and starting to supply the alternating current to the heater by the power source for supplying under this timing.