Image forming apparatus

An image forming apparatus, comprising:

• a photosensitive element;
• a charging unit that charges a surface of the photosensitive element;
• a writing unit that forms a static latent image on the photosensitive element by irradiating the charged surface of the photosensitive element with light based on input image data;
• a developing unit that supplies toner to the static latent image on the photosensitive element so as to form a toner image;
• an endless intermediate transfer member;
• an intermediate transfer unit that transfers the toner image on the photosensitive element onto the intermediate transfer member;
• a recording medium transfer unit that transfers the toner image on the intermediate transfer member onto a recording medium;
• and
• a fixing unit that fixes the toner image to the recording medium by applying heat and pressure to the toner image, wherein
• the writing unit includes:
• a data buffer unit that buffers the input image data;
• an image data generation unit that produces image data;
• a main-sub image magnification processing unit that performs image magnification processing in a main-scanning direction and a sub-scanning direction;
• a clock generation unit that changes a writing clock period;
• a correction map that retains image magnification information corresponding to a deformation of the recording medium caused by application of heat and pressure from the fixing unit;
• and
• a light-emitting device that irradiates the photosensitive element with light on the basis of drive data from the image data generation unit, and
• the writing unit is configured to slightly change the writing clock period so as to enlarge or shrink a formed pixel in the main-scanning direction and further perform enlargement or shrinkage in the sub-scanning direction with reference to the image magnification information of the correction map, and thus cancel an image deformation caused by the deformation of the recording medium and correct a change in an image magnification in the main-scanning direction.

An image forming apparatus, comprising:

• a photosensitive element;
• a charging unit that charges a surface of the photosensitive element;
• a writing unit that forms a static latent image on the photosensitive element by irradiating the charged surface of the photosensitive element with light based on input image data;
• a developing unit that supplies toner to the static latent image on the photosensitive element so as to form a toner image;
• a transfer unit that transfers the toner image onto a recording medium;
• a fixing unit that fixes the toner image to the recording medium by applying heat and pressure to the toner image;
• and
• sensors that are provided at an entrance and an exit of the recording medium to and from the fixing unit and detect an amount of a deformation of the recording medium occurring when the recording medium passes through the fixing unit, wherein
• the writing unit includes:
• a data buffer unit that buffers the input image data;
• an image data generation unit that produces image data;
• a main-sub image magnification processing unit that performs image magnification processing in a main-scanning direction and a sub-scanning direction;
• a clock generation unit that changes a writing clock period;
• and
• a light-emitting device that irradiates the photosensitive element with light on the basis of drive data from the image data generation unit,
• image magnification information is produced on the basis of deformation amount information of the recording medium from the sensors, and
• the writing unit is configured to slightly change the writing clock period so as to enlarge or shrink a formed pixel in the main-scanning direction and further perform enlargement or shrinkage in the sub-scanning direction with reference to the image magnification information of the correction map, and thus cancel an image deformation caused by the deformation of the recording medium and correct a change in an image magnification in the main-scanning direction.