IMAGE FORMING APPARATUS, CONTROL METHOD THEREFOR, AND STORAGE MEDIUM STORING CONTROL PROGRAM THEREFOR

• US 20130266329A1
• Filed: 03/13/2013
• Published: 10/10/2013
• Est. Priority Date: 04/05/2012
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Otani, Atsushi
• Granted Patent: US 9,207,569 B2
• Time in Patent Office: Days
• US Class Current: 399/27
• CPC Class Codes: G03G 15/0849 Detection or control means for the developer concentration
• CPC Class Codes: G03G 15/086 the level being measured by electro-magnetic means

Abstract

An image forming apparatus that is capable of reducing an effect of variation of specific inductive capacity of toner due to environmental variation with a small detection error when the remaining toner amount is detected. The image forming apparatus forms an image with an electrophotographic system. A container unit stores toner. A toner detection unit has sensor modules that are arranged at positions where the toner is stagnated in the container unit, and that show different electrostatic capacities with respect to the same toner thickness. An electrostatic capacity detection unit detects the electrostatic capacities of the sensor modules. A determination unit determines a remaining toner amount in the container unit based on the electrostatic capacities of the sensor modules that are detected by the electrostatic capacity detection unit.

Claims

1. An image forming apparatus that forms an image with an electrophotographic system, comprising:

a container unit configured to store toner,

a toner detection unit configured to have a plurality of sensor modules that are arranged at positions where the toner is stagnated in said container unit, and that show different electrostatic capacities with respect to the same toner thickness;

an electrostatic capacity detection unit configured to detect the electrostatic capacities of the sensor modules; and

a determination unit configured to determine a remaining toner amount in said container unit based on the electrostatic capacities of the sensor modules that are detected by said electrostatic capacity detection unit.

2. The image forming apparatus according to claim 1, wherein said determination unit calculates a ratio of the electrostatic capacities of the sensor modules that are detected by said electrostatic capacity detection unit, and determines the remaining toner amount in said container unit based on the calculated ratio.

3. The image forming apparatus according to claim 2, further comprising:

a first storage unit configured to store a conversion table that defines a relation between a ratio of electrostatic capacities of the sensor modules and toner thickness,

wherein said determination unit acquires the toner thickness by checking the ratio of the electrostatic capacities against the conversion table, and determines the remaining toner amount based on the acquired toner thickness.

4. The image forming apparatus according to claim 2, further comprising:

a second storage unit configured to store standard electrostatic capacities for correcting the electrostatic capacities of the sensor modules individually,

wherein said determination unit calculates the ratio of the electrostatic capacities using electrostatic capacities acquired by subtracting the corresponding standard electrostatic capacities from the electrostatic capacities of the sensor modules that are detected by said electrostatic capacity detection unit.

5. The image forming apparatus according to claim 4, wherein the standard electrostatic capacities are electrostatic capacities of the sensor modules when the toner does not exist.

6. The image forming apparatus according to claim 1, wherein each of the sensor modules consists of a pair of electrodes formed by arranging conductors of predetermined line width at predetermined spacing, and the sensor modules are different in at least one of the line width and the spacing so that the sensor modules show different electrostatic capacities with respect to the same toner thickness.

7. The image forming apparatus according to claim 1, wherein each of the sensor modules consists of a pair of electrodes formed by arranging conductors of predetermined line width at predetermined spacing, and the sensor modules are different in distance from the pair of electrodes to a toner detection face in said container unit so that the sensor modules show different electrostatic capacities with respect to the same toner thickness.

8. The image forming apparatus according to claim 1, further comprising:

a temperature sensor configured to detect internal temperature,

wherein said determination unit corrects the electrostatic capacities of the sensor modules that are detected by said electrostatic capacity detection unit based on the temperature detected by said temperature sensor.

9. The image forming apparatus according to claim 2, wherein said toner detection unit has at least three sensor modules, and said determination unit calculates ratios based on the electrostatic capacities of the at least three sensor modules, acquires estimated values that presume the remaining toner amount in said container unit based on the calculated ratios, and determines the remaining toner amount based on an average of the estimated values.

10. The image forming apparatus according to claim 9, wherein said determination unit calculates at least three ratios based on at least three electrostatic capacities of the at least three sensor modules, acquires at least three estimated values that presume the remaining toner amount in said container unit based on the at least three calculated ratios, and determines the remaining toner amount based on an average of the estimated values when the maximum difference among these estimated values is below a first threshold value.

11. The image forming apparatus according to claim 9, wherein said determination unit calculates at least three ratios based on at least three electrostatic capacities of the at least three sensor modules, acquires at least three estimated values that presume the remaining toner amount in said container unit based on the at least three calculated ratios, selects an estimated value that is farthest from an average of the at least three estimated values as an invalid estimated value, and determines the remaining toner amount based on an average of the estimated values other than the invalid estimated value when the maximum difference among these estimated values is more than a first threshold value and is below a second threshold value that is larger than the first threshold value.

12. The image forming apparatus according to claim 9, wherein said determination unit calculates at least three ratios based on at least three electrostatic capacities of the at least three sensor modules, acquires at least three estimated values that presume the remaining toner amount in said container unit based on the at least three calculated ratios, and determines the remaining toner amount based on the minimum estimated value when the maximum difference among these estimated values is more than a first threshold value and is more than a second threshold value that is larger than the first threshold value.

13. A control method for an image forming apparatus that forms an image with an electrophotographic system, and that has a container unit that stores toner, a toner detection unit that has a plurality of sensor modules that are arranged at positions where the toner is stagnated in the container unit and that show different electrostatic capacities with respect to the same toner thickness, the control method comprising:

an electrostatic capacity detection step of detecting the electrostatic capacities of the sensor modules; and

a determination step of determining a remaining toner amount in the container unit based on the electrostatic capacities of the sensor modules that are detected in said electrostatic capacity detection step.

14. The control method for the image forming apparatus according to claim 13, further comprising:

an electrostatic capacity ratio calculation step of calculating a ratio of the electrostatic capacities of the sensor modules detected in said electrostatic capacity detection step,

wherein the remaining toner amount in the container unit is determined based on the calculated ratio in said determination step.

15. The control method for the image forming apparatus according to claim 14, further comprising:

a toner thickness detection step of acquiring the toner thickness by checking the ratio of the electrostatic capacities against a conversion table that defines a relation between a ratio of electrostatic capacities of the sensor modules and toner thickness,

wherein the remaining toner amount in the container unit is determined based on the toner thickness in said determination step.

16. The control method for the image forming apparatus according to claim 14, further comprising:

a standard electrostatic capacity subtraction step of subtracting standard electrostatic capacities for correcting the electrostatic capacities of the sensor modules individually from the corresponding electrostatic capacities of the sensor modules that are detected in said electrostatic capacity detection step,

wherein the ratio of the electrostatic capacities is calculated using the electrostatic capacities acquired by the subtraction in said electrostatic capacity ratio calculation step.

17. A non-transitory computer-readable storage medium storing a control program causing a computer to execute a control method for an image forming apparatus that forms an image with an electrophotographic system, and that has a container unit that stores toner, a toner detection unit that has a plurality of sensor modules that are arranged at positions where the toner is stagnated in the container unit and that show different electrostatic capacities with respect to the same toner thickness, the control method comprising:

an electrostatic capacity detection step of detecting the electrostatic capacities of the sensor modules;

an electrostatic capacity ratio calculation step of calculating a ratio of the electrostatic capacities of the sensor modules detected in said electrostatic capacity detection step;

a toner thickness detection step of acquiring the toner thickness by checking the ratio of the electrostatic capacities against a conversion table that defines a relation between a ratio of electrostatic capacities of the sensor modules and toner thickness; and

a determination step of determining the remaining toner amount in the container unit based on the toner thickness detected in said toner thickness detection step.

18. The storage medium according to claim 17, the control method further comprising:

an electrostatic capacity ratio calculation step of calculating a ratio of the electrostatic capacities of the sensor modules detected in said electrostatic capacity detection step,

wherein the remaining toner amount in the container unit is determined based on the calculated ratio in said determination step.

19. The storage medium according to claim 18, the control method further comprising:

a toner thickness detection step of acquiring the toner thickness by checking the ratio of the electrostatic capacities against a conversion table that defines a relation between a ratio of electrostatic capacities of the sensor modules and toner thickness,

wherein the remaining toner amount in the container unit is determined based on the detected toner thickness in said determination step.

20. The storage medium according to claim 18, the control method further comprising:

a standard electrostatic capacity subtraction step of subtracting standard electrostatic capacities for correcting the electrostatic capacities of the sensor modules individually from the corresponding electrostatic capacities of the sensor modules that are detected in said electrostatic capacity detection step,

wherein the ratio of the electrostatic capacities is calculated using the electrostatic capacities acquired by the subtraction in said electrostatic capacity ratio calculation step.