Image formation apparatus and method of adjusting developer discard amount for the same
View Patent ↗An image formation apparatus includes an exposure unit to form an electrostatic latent image with image dots on a rotatable image carrier by exposing the image carrier to irradiation light, a development unit to form a developer image by attaching a developer to the electrostatic latent image, a voltage supply unit to supply the development unit with a development voltage, a cleaning unit to clean up the developer left on the image carrier after the development, and a developer discard amount controller to control an amount of the developer to be forcibly attached to the image carrier based on a total rotation number of the image carrier if the number of image dots printed during a prescribed number of rotations of the image carrier is smaller than a reference value, and to forcibly attach the controlled amount of the developer to the image carrier to discard the developer.
1. An image formation apparatus comprising:
a rotatable image carrier configured to carry an electrostatic latent image;
an exposure unit configured to form the electrostatic latent image with a certain number of image dots by exposing the image carrier to irradiation light;
a development unit configured to form a developer image by attaching a developer to the electrostatic latent image with a development voltage;
a voltage supply unit configured to supply the development unit with the development voltage;
an image formation unit configured to transfer the developer image onto a recording medium;
a cleaning unit configured to cleanup the developer left on the image carrier after the transfer of the developer image; and
a developer discard amount controller configured to control an amount of the developer to be forcibly attached to the image carrier from the development unit on the basis of a total number of rotations of the image carrier if the number of image dots printed during a prescribed number of rotations of the image carrier is smaller than a reference value, and to forcibly attach a controlled amount of the developer to the image carrier to discard the developer.
2. The image formation apparatus according to claim 1 , wherein the developer discard amount controller reduces the amount of developer to be forcibly attached to the image carrier as the total number of rotations of the image carrier increases.
3. The image formation apparatus according to claim 1 , further comprising an exposure amount controller configured to change an amount of the irradiation light from the exposure unit, wherein
the developer discard amount controller includes:
the voltage supply unit;
a first controller configured to control the exposure amount controller and a rotation operation of the image carrier;
the exposure amount controller;
a rotation number measurement unit configured to measure the total number of rotations of the image carrier and to output a rotation measurement value thus measured;
an image dot number measurement unit configured to measure the number of image dots exposed by the exposure unit and to output a dot measurement value thus measured;
a dot number calculation unit configured to calculate the number of image dots printed during the prescribed number of rotations from the rotation measurement value and the dot measurement value and to output a dot number calculation result;
a dot number comparison unit configured to compare the dot number calculation result with the reference value being a predetermined number of image dots corresponding to the prescribed number of rotations of the image carrier and to output a comparison result; and
a second controller configured to control an overall operation of the voltage supply unit, the first controller, the exposure amount controller, the rotation number measurement unit, the image dot number measurement unit, the dot number calculation unit, and the dot number comparison unit, and
the developer discard amount controller controls the amount of developer on the development unit to be forcibly attached to the image carrier on the basis of the total number of rotations if the comparison result shows that the dot number calculation result is smaller than the predetermined reference value, and forcibly attaches the controlled amount of developer to the image carrier to discard the developer.
4. The image formation apparatus according to claim 3 , wherein the second controller controls the exposure amount controller by way of the first controller in such a way that the light amount of the irradiation light is changed based on the total number of rotations of the image carrier.
5. The image formation apparatus according to claim 3 , wherein the second controller controls the voltage supply unit in such a way that the development voltage is changed based on the total number of rotations of the image carrier.
6. The image formation apparatus according to claim 3 , wherein
the developer discard amount controller further includes a storage unit configured to store therein a first table having the rotation measurement value and the light amount corresponding to an amount of developer to be discarded which is determined as reducible according to the rotation measurement value, and
when discarding the developer, the developer discard amount controller reads the light amount according to the rotation measurement value from the first table and controls the exposure amount controller in such a way that the light amount from the exposure unit is changed to the read light amount.
7. The image formation apparatus according to claim 3 , wherein
the developer discard amount controller further includes a storage unit configured to store therein a second table having the rotation measurement value and the development voltage corresponding to an amount of developer to be discarded which is determined as reducible according to the rotation measurement value, and
when discarding the developer, the developer discard amount controller reads the development voltage according to the rotation measurement value from the second table and controls the voltage supply unit in such a way that the development voltage is changed to the read development voltage.
8. A method of adjusting a developer discard amount for an image formation apparatus comprising:
forming an electrostatic latent image on an image carrier with a certain number of image dots by exposing the image carrier to irradiation light;
forming a developer image by attaching a developer to the electrostatic latent image with a development voltage;
transferring the developer image onto a recording medium;
cleaning up the excess developer left on the image carrier after the transfer of the developer image; and
controlling an amount of the developer to be forcibly attached to the image carrier, wherein said controlling comprises:
an image dot number judgment step of judging whether or not a number of image dots printed during a prescribed number of rotations of the image carrier is smaller than a reference value;
a developer discard amount adjustment step of adjusting an amount of the developer to be forcibly attached to the image carrier from the development unit on the basis of a total number of rotations of the image carrier if a result of the image dot number judgment step is smaller than the reference value; and
a developer discard step of discarding the developer in the amount of the developer adjusted in the developer discard amount adjustment step by forcibly attaching the developer to the image carrier.
9. The method according to claim 8 , wherein
the developer discard amount adjustment step controls the amount of the irradiation light based on the total number of rotations of the image carrier.
10. The method according to claim 8 , wherein
the developer discard amount adjustment step controls the development voltage based on the total number of rotations of the image carrier.