IMAGE READING APPARATUS, IMAGE READING UNIT THEREOF, AND REFERENCE MEMBER THEREOF FOR SHADING CORRECTION

Abstract

An image reading apparatus which is capable of performing accurate shading correction with simple arrangement while preventing a reference member from being scratched and paper powder and the like dust from being deposited on the reference member. The image reading apparatus comprises an image reading unit. In the image reading unit, a contact glass guides an original on an image reading location. The contact glass is held by a glass holding member. A line image sensor reads the image on the original conveyed on the image reading location, through the contact glass. The image reading unit further comprises a reference member whose image is readable by the image sensor, and a moving mechanism to move the image sensor so as to enable the image sensor to alternatively read the original and a reference surface of the reference member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side cross-sectional view showing the internal construction of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram showing the electrical configuration of the image reading apparatus in FIG. 1.

FIGS. 3A and 3B are cross-sectional views of an image reading unit appearing in FIG. 1, in a state during an original reading period, in which:

FIG. 3A shows the image reading unit as viewed vertically; and

FIG. 3B shows the image reading unit as viewed horizontally.

FIGS. 4A and 4B are cross-sectional views of the image reading unit in a state during a reference member reading period, in which:

FIG. 4A shows the image reading unit as viewed vertically; and

FIG. 4B shows the image reading unit as viewed horizontally.

FIGS. 5A and 5B are views of a drive section appearing in FIG. 1 and component parts associated therewith as viewed from above, in which:

FIG. 5A shows a state during the original reading period; and

FIG. 5B shows a state during the reference member reading period.

FIGS. 6A and 6B are views of the drive section and component parts associated therewith, as viewed in an original conveying direction, in which:

FIG. 6A shows a state in which the apparatus is closed during the original reading period; and

FIG. 6B shows a state in which the apparatus is open during the reference member reading period.

FIG. 7 is a diagram showing an output waveform obtained when an image reading operation is performed by a line image sensor while a pulse motor is rotated at a constant speed.

FIGS. 8A and 8B are partial vertical cross-sectional views showing another example of the image reading unit, in which:

FIG. 8A shows a state during the original reading period; and

FIG. 8B shows a state during the reference member reading period.

FIGS. 9A and 9B are partial vertical cross-sectional views showing still another example of the image reading unit, in which:

FIG. 9A shows a state during the original reading period; and

FIG. 9B shows a state during the reference member reading period.

FIGS. 10A to 10D are partial cross-sectional views showing an example of the layout of a reference member, in which:

FIG. 10A shows a case where the reference member is disposed on an opposite surface of a contact glass from an original conveying surface thereof;

FIG. 10B shows a case where the reference member is disposed on an original conveying surface of a glass holding member;

FIG. 10C shows a case where the reference member is disposed on an opposite surface of the glass holding member from the original conveying surface thereof; and

FIG. 10D shows a case where a junction part is omitted from the layout shown in FIG. 10B.

FIG. 11 is a schematic view of an image reading apparatus according to a second embodiment of the present invention.

FIG. 12 is a schematic view of a variation of the image reading apparatus in FIG. 11.

FIG. 13 is a schematic view of another variation of the image reading apparatus in FIG. 11.

FIG. 14 is a schematic view of a line image sensor provided in an image reading unit appearing in FIG. 11.

FIGS. 15A and 15B are cross-sectional views showing the image reading unit and its surrounding, in which:

FIG. 15A shows a state during the original reading period; and

FIG. 15B shows a state during a shading correction data acquisition period.

FIG. 16 is a perspective view of the image reading unit.

FIG. 17 is a flowchart of a shading correction process executed by a CPU.

FIGS. 18A and 18B are cross-sectional views showing the image reading unit according to a variation and its surrounding, in which:

FIG. 18A shows a state during the original reading period; and

FIG. 18B shows a state during the shading correction data acquisition period.

FIG. 19 is a schematic side view of an image reading apparatus according to a third embodiment of the present invention.

FIG. 20 is a schematic side view of a reference member appearing in FIG. 19.

FIG. 21 is a schematic side view of a variation of the reference member in FIG. 20.

FIG. 22 is a side view showing the internal construction of a conventional image reading apparatus.

FIG. 23 is a schematic side view of an image reading unit of the conventional image reading apparatus.

Claims

1. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising: an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move said image sensor so as to enable said image sensor to read alternatively the original conveyed on the image reading location and said reference member,wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path.

2. An image reading apparatus according to claim 1, wherein the reference surface of said reference member is held in close contact with said contact glass.

3. An image reading apparatus according to claim 1, wherein said reference member is disposed on said glass holding member.

4. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising: an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path, and said reference member is disposed on an original conveying path-side surface of said contact glass.

5. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising: an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path, and said reference member is fixed to an opposite surface of an original conveying path-side surface of said contact glass.

6. An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising: an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,wherein said reference member comprises a white coating film formed on an original conveying path-side surface of said contact glass, and a protective member covering at least a portion of said white coating film, for protection of said white coating film.

7. An image reading apparatus configured to read an image formed on an original, comprising: an image reading unit including a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in said frame, a contact glass disposed on the opening of said frame, configured to guide the original to an image reading location thereon, and a reference member disposed within said frame.

8. An image reading unit provided in an image reading apparatus as claimed in claim 7.

9. An image reading apparatus for reading an image formed on an original, while conveying the original, comprising: a contact glass configured to have an original conveying surface on which an original reading position and a reference member reading position exist, and guide the original on the original conveying surface;an image sensor configured to be capable of moving a reading position thereof between a position opposed to the original reading position and a position opposed to the reference member reading position, and read the image formed on the original through said contact glass guided on the original conveying surface of said contact glass; anda shading correction reference member as a white reference for said image sensor,wherein said shading correction reference member comprises a white coating film formed on an original conveying path-side surface of said contact glass, and a protective member covering at least a portion of said white coating film, for protection of said white coating film.

10. An image reading apparatus according to claim 9, wherein said protective member is a substantially white adhesive tape.

11. An image reading apparatus according to claim 9, wherein said protective member is substantially white, and wherein said shading correction reference member has a transparent fixing member provided between said protective member and said white coating film, for fixing said protective member to a surface of said white coating film.

12. An image reading apparatus according to claim 9, wherein said shading correction reference member has a substantially white fixing member provided between said protective member and said white coating film, for fixing said protective member to a surface of said white coating film.

13. An image reading apparatus according to claim 9, wherein said shading correction reference member has a two-sided adhesive tape for fixing said protective member, in a manner opposed to said white coating film, to at least one of a portion of said white coating film and a portion of said contact glass other than a portion close to said reference member reading location.

14. An image reading apparatus according to claim 11, wherein said fixing member is a two-sided adhesive tape.

15. An image reading apparatus according to claim 11, wherein said fixing member is an adhesive.

16. An image reading apparatus according to claim 11, wherein said protective member is a sheet form member.

17. An image reading apparatus according to claim 11, wherein said protective member is a sheet metal member.

18. A shading correction reference member disposed at a reference member reading location on a contact glass provided in an image reading apparatus, comprising: a white coating film formed on an original conveying path-side surface of the contact glass; anda protective member covering at least a portion of said white coating film, for protection of said white coating film.