Image reading device, image forming apparatus, and shading data processing method

• US 10,063,744 B2
• Filed: 09/27/2016
• Issued: 08/28/2018
• Est. Priority Date: 10/19/2015
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Miyazaki, Susumu, Yoshida, Tomoyuki, Inui, Tetsuo, Imoto, Shigefumi
• Primary Examiner(s): Nguyen, Madelein
• Application Number:
  US15/276,892
• Publication Number:
  US 20170111549A1
• Time in Patent Office: 700 Days
• Field of Search: None
• CPC Class Codes: H02N 1/12 in the form of a conveyor belt, e.g. van de Graaff machine
• CPC Class Codes: H04N 1/0313 Direct contact pick-up heads, i.e. heads having no array of elements to project the scanned image elements onto the photodectors
• CPC Class Codes: H04N 1/12 using the sheet-feed movement or the medium-advance or the drum-rotation movement as the slow scanning component, e.g. arrangements for the main-scanningsheet-feed movement by translatory movement of a flat picture-bearing surface H04N1/1008; main-scanning using oscillating or rotating mirrors H04N1/113; using multi-element arrays H04N1/19
• CPC Class Codes: H04N 1/2034 at identical corresponding positions, i.e. without time delay between the two image signals
• CPC Class Codes: H04N 1/407 Control or modification of tonal gradation or of extreme levels, e.g. background level
• CPC Class Codes: H04N 1/4095 Correction of errors due to scanning a two-sided document, i.e. show-through correction
• CPC Class Codes: H04N 2201/0081 Image reader H04N2201/0091 - H04N2201/0094 take precedence

Abstract

An image reading device includes a first unit to read one surface of a document in a first area facing a document path, a second unit disposed in the first area to read the other surface of the document, a first reference member facing the first unit at a first distance therefrom at a second position in a second area not facing the path, a second reference member facing the first unit at a second distance therefrom at a first position in the first area, a third reference member facing the second unit at the second distance therefrom, and a correction unit to correct, based on a difference between first data generated through reading of the first member by the first unit and second data generated through reading of the second member by the first unit, third data generated through reading of the third member by the second unit.

Claims

1. An image reading device comprising:

a first image reading unit movable between a first area facing a document transport path and a second area not facing the document transport path, and configured to read, in the first area, a first surface of a document transported on the document transport path;

a second image reading unit disposed in the first area and configured to read a second surface of the document;

a first shading reference member facing the first image reading unit at a first distance therefrom when the first image reading unit is located at a second position in the second area, wherein the first image reading unit is configured to read the first shading reference member to acquire first shading data;

a second shading reference member facing the first image reading unit at a second distance therefrom across the document transport path when the first image reading unit is located at a first position in the first area, wherein the first image reading unit is configured to read the second shading reference member to acquire second shading data;

a third shading reference member facing the second image reading unit at the second distance therefrom across the document transport path, wherein the second image reading unit is configured to read the third shading reference member to acquire third shading data; and

a controller comprising a memory storing computer-readable instructions and a processor configured to execute the computer-readable instructions to correct an error in the third shading data, resulting from a distance from the second image reading unit to the third shading reference member being different from a distance from the second image reading unit to the document transported on the document transport path, by,

determining a difference between the first shading data and the second shading data,

correcting the third shading data based on the difference between the first shading data and the second shading data to acquire corrected third shading data,

comparing a maximum value of the corrected third shading data with a threshold value, and

adjusting, in response to the maximum value of the corrected third shading data being outside a tolerance range of the threshold value, a light amount of a light source of the second image reading unit to set the maximum value of the corrected third shading data within the tolerance range of the threshold value, whereby the maximum value of the corrected third shading data is adjusted to a maximum value of the first shading data.

2. The image reading device of claim 1, wherein the first distance corresponds to a distance from the first image reading unit located at the first position in the first area to a part of the document transport path facing the first image reading unit.

3. The image reading device of claim 1, further comprising a document table on which a document is placed to be read by the first image reading unit moving in the second area.

4. The image reading device of claim 1, wherein the processor of the controller is further configured to execute the computer-readable instructions to standardize the corrected third shading data based on a calculation performed on the third shading data to adjust the maximum value of the corrected third shading data to the maximum value of the first shading data.

5. The image reading device of claim 1, wherein the processor of the controller is further configured to execute the computer-readable instructions to correct misalignment between main scanning pixels of data read by the first image reading unit and main scanning pixels of data read by the second image reading unit.

6. The image reading device of claim 1, wherein:

the first image reading unit is configured to read the first shading reference member to acquire a read value; and

the processor of the controller is further to configured to execute the computer-readable instructions to adjust a light amount of a light source of the first image reading unit such that a maximum value of the read value acquired equals the threshold value, prior to acquiring the first shading data.

7. The image reading device of claim 1, wherein:

the second image reading unit is configured to read the third shading reference member to acquire a read value; and

the processor of the controller is further to configured to execute the computer-readable instructions to adjust a light amount of a light source of the second image reading unit such that a maximum value of the read value acquired equals a difference between (i) the threshold value and (ii) a maximum value of the difference between the first shading data and the second shading data, prior to acquiring the third shading data.

8. The image reading device of claim 1, wherein the processor of the controller is configured to execute the computer-readable instructions to adjust the light amount of the light source of the second image reading unit such that a read value at a position x of a main scanning pixel at which a value of the third shading data is maximized equals a difference between (i) the threshold value and (ii) the difference between the first shading data and the second shading data at the position x.

9. An image forming apparatus comprising the image reading device of claim 1.

10. A shading data processing method performed by an image reading device including a first image reading unit and a second image reading unit, the first image reading unit being movable between a first area facing a document transport path and a second area not facing the document transport path, and configured to read, in the first area, a first surface of a document transported on the document transport path, the second image reading unit being disposed in the first area and configured to read a second surface of the document, the shading data processing method comprising:

acquiring first shading data through reading, with the first image reading unit and at a second position in the second area, a first shading reference member facing the first image reading unit as at a first distance therefrom;

acquiring second shading data through reading, with the first image reading unit and at a first position in the first area, a second shading reference member facing the first image reading unit at a second distance therefrom across the document transport path;

acquiring third shading data through reading, with the second image reading unit, a third shading reference member facing the second image reading unit at the second distance therefrom across the document transport path; and

correcting an error in the third shading data, resulting from a distance from the second image reading unit to the third shading reference member being different from a distance from the second image reading unit to the document transported on the document transport path, by,

determining a difference between the first shading data and the second shading data,

correcting the third shading data based on the difference between the first shading data and the second shading data to acquire corrected third shading data,

comparing a maximum value of the corrected third shading data with a threshold value, and

adjusting, in response to the maximum value of the corrected third shading data being outside a tolerance range of the threshold value, a light amount of a light source of the second image reading unit to set the maximum value of the corrected third shading data within the tolerance range of the threshold value, whereby the maximum value of the corrected third shading data is adjusted to a maximum value of the first shading data.