Image reading apparatus, image forming apparatus, and image reading method

Abstract

To provide an image forming apparatus and an image reading method that ensure the high accuracy in correcting shading.SOLUTION: An image reading device has: a density reference member 302; a light source 24 that illuminates the density reference member with light; an imaging unit 28 that outputs a read image of the density reference member; driving means 304 that changes the relative position between the density reference member and the imaging unit; a foreign substance detection unit 305 that detects foreign substance in the read image; and a generation unit 306 that generates, from the read image, correction data used for correcting shading that is unevenness in brightness. The imaging unit reads a first read image while the relative position is changed in a predetermined direction by the driving means, and reads a second read image while the relative position is changed in a direction opposite to the predetermined direction by the driving means. The detection means detects foreign substances in the first read image and the second read image. The generation means generates the correction data from one of the first read image and the second read image which has less foreign substances.SELECTED DRAWING: Figure 3

Claims

1. Concentration reference member, A light source that illuminates the aforementioned concentration reference member, An imaging unit that outputs a reading image of the density reference member, A driving means for changing the relative position between the density reference member and the imaging unit, A detection means for detecting foreign objects in the read image, The system includes a generation means for generating correction data from the read image, which is used to correct shading, which is unevenness in brightness. The aforementioned concentration reference member is a plate-shaped member, The imaging unit reads a first image while the relative position is changed in a predetermined direction by the driving means, and reads a second image while the relative position is changed in the opposite direction to the predetermined direction by the driving means. The detection means detects the foreign object in the first read image and the second read image, The generation means is an image reading device that generates the correction data using only the reading image of the first reading image and the second reading image in which the amount of foreign matter detected by the detection means is smaller.

2. The image reading device according to claim 1, wherein the generation means determines the region in which the foreign object is detected as an invalid region for each of the first and second read images, and generates the correction data based on the valid region.

3. The image reading device according to claim 1, wherein the driving means moves the density reference member by a predetermined distance or more in the main scanning direction.

4. The image reading apparatus according to any one of claims 1 to 3, wherein the generation means generates correction data for correcting shading in the main scanning direction based on a plurality of line images included in the first read image or the second read image.

5. The image reading device according to any one of claims 1 to 4, wherein the imaging unit reads the first read image and the second read image during the first reading operation by the imaging unit in a job in which the imaging unit performs reading operations multiple times, and during reading operations by the imaging unit at predetermined intervals.

6. The image reading device according to any one of claims 1 to 5, wherein when the driving means performs a job that involves reading operations by the imaging unit multiple times, for the second and subsequent reading operations by the imaging unit, the relative position is changed in the opposite direction to the direction of change of the relative position immediately preceding the reading operation.

7. An image reading device according to any one of claims 1 to 6, An image forming apparatus comprising an image forming unit.

8. An image reading method using an image reading device, wherein the image reading device is The light source illuminates the density reference member, The imaging unit outputs a reading image of the density reference member. The driving means changes the relative position between the density reference member and the imaging unit, The detection means detects foreign objects in the read image, The generation means generates correction data from the read image, which is used to correct shading, which is unevenness in brightness. The aforementioned concentration reference member is a plate-shaped member, The imaging unit reads a first image while the relative position is changed in a predetermined direction by the driving means, and reads a second image while the relative position is changed in the opposite direction to the predetermined direction by the driving means. The detection means detects the foreign object in the first read image and the second read image, The generation means is an image reading method that generates the correction data using only the reading image of the first reading image and the second reading image in which the amount of foreign matter detected by the detection means is smaller.

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