Toner calculation in an image forming device

1. An image forming apparatus that consumes toner to form an image, the apparatus comprising:

a first calculation portion that calculates a toner consumption by a first calculation method;

a second calculation portion that calculates the toner consumption by a second calculation method according to a predetermined calculation formula after a predetermined switching criterion is satisfied; and

a third calculation portion that calculates a value of a parameter in the predetermined calculation formula of the second calculation method based on the toner consumption calculated by the first calculation method,

wherein:

the second calculation portion calculates the toner consumption based on data values regarding a plurality of pixel attributes in image data and respective parameters for the plurality of pixel attributes;

the third calculation portion calculates the values of the respective parameters for the plurality of pixel attributes from the data values regarding the plurality of pixel attributes calculated within each of a plurality of periods and the toner consumption calculated by the first calculation method within each of the plurality of periods;

the plurality of pixel attributes comprises a gradation attribute;

the value of the parameter for the gradation attribute is fixed;

the second calculation portion calculates the toner consumption based on the data value regarding at least one remaining pixel attribute and the parameter for the at least one remaining pixel attribute; and

the third calculation portion calculates the value of the respective parameter for the at least one remaining pixel attribute from the data value regarding the at least one remaining pixel attribute calculated within each of at least one period and the toner consumption calculated by the first calculation method within each of the at least one period.

2. The image forming apparatus according to claim 1 , wherein:

the second calculation portion calculates the toner consumption based on a sum of products of printing ratios regarding the plurality of pixel attributes in the image data and the respective parameters for the plurality of pixel attributes; and

the third calculation portion calculates the values of the respective parameters for the plurality of pixel attributes from the printing ratios regarding the plurality of pixel attributes calculated within each of a plurality of periods and the toner consumption calculated by the first calculation method within each of the plurality of periods.

3. The image forming apparatus according to claim 1 , wherein:

the plurality of pixel attributes comprise a character attribute and a gradation attribute.

4. The image forming apparatus according to claim 1 , wherein the number of the plurality of periods is equal to or larger than the number of the plurality of pixel attributes.

5. The image forming apparatus according to claim 1 , wherein the plurality of periods each have a duration longer than a fluctuation cycle of the toner consumption calculated by the first calculation method.

6. The image forming apparatus according to claim 1 , wherein:

the predetermined switching criterion comprises whether or not an integrated value of the toner consumption calculated by the first calculation method has reached a predetermined threshold value; and

the predetermined threshold value comprises a value within a range in which a toner supplying time and the integrated value of the toner consumption are substantially proportional to each other.

7. The image forming apparatus according to claim 1 , wherein the first calculation portion calculates the toner consumption based on one of an operation count and an operating time of a toner carrying portion that carries the toner from a toner cartridge.

8. A toner consumption calculation method of calculating a toner consumption that is an amount of toner consumed in image formation, comprising:

a first toner calculating comprising calculating the toner consumption by a first calculation method;

a second toner calculating comprising calculating the toner consumption by a second calculation method according to a predetermined calculation formula after a predetermined switching criterion is satisfied; and

a parameter calculating comprising calculating a value of a parameter in the predetermined calculation formula of the second calculation method based on the toner consumption calculated by the first calculation method,

wherein:

the second toner calculating comprises calculating the toner consumption based on data value regarding a plurality of pixel attributes in image data and respective parameters for the plurality of pixel attributes;

the parameters calculating comprises calculating the values of the respective parameters for the plurality of pixel attributes from the data values regarding the plurality of pixel attributes calculated within each of the plurality of periods and the toner consumption calculated by the first calculation method within each of the plurality of periods;

the plurality of pixel attributes comprise a gradation attribute;

the value of the parameter for the gradation attribute is fixed;

the second toner calculating comprises calculating the toner consumption based on the data value regarding at least one remaining pixel attribute and the parameter for the at least one remaining pixel attribute; and

the parameter calculating comprises calculating the value of the respective parameter for the at least one remaining pixel attribute from the data value regarding the at least one remaining pixel attribute calculated within each of the at least one period and the toner consumption calculated by the first calculation method within each of the at least one period.

9. The toner consumption calculation method according to claim 8 , wherein:

the second toner calculating comprises calculating the toner consumption based on a sum of products of printing ratios regarding the plurality of pixel attributes in the image data and the respective parameters for the plurality of pixel attributes; and

the parameter calculating comprises calculating the values of the respective parameters for the plurality of pixel attributes from the printing ratios regarding the plurality of pixel attributes calculated within each of the plurality of periods and the toner consumption calculated by the first calculation method within each of the plurality of periods.

10. The toner consumption calculation method according to claim 8 , wherein: the plurality of pixel attributes comprise a character attribute and a gradation attribute.

11. The toner consumption calculation method according to claim 8 , wherein the number of the plurality of periods is equal to or larger than the number of the plurality of pixel attributes.

12. The toner consumption calculation method according to claim 8 , wherein the plurality of periods each have a duration longer than a fluctuation cycle of the toner consumption calculated by the first calculation method.

13. The toner consumption calculation method according to claim 8 , wherein:

the predetermined switching criterion comprises whether or not an integrated value of the toner consumption calculated by the first calculation method has reached a predetermined threshold value; and

the predetermined threshold value comprises a value within a range in which a toner supplying time and the integrated value of the toner consumption are substantially proportional to each other.

14. The toner consumption calculation method according to claim 8 , wherein the first toner calculating comprises calculating the toner consumption based on one of an operation count and an operating time of a toner carrying portion that carries the toner from a toner cartridge.

15. The toner consumption calculation method according to claim 8 , wherein:

the plurality of pixel attributes comprise a character attribute, a gradation attribute, and a vector graphics attribute.