IMAGE READING APPARATUS, SHADING CORRECTION METHOD THEREFOR, AND PROGRAM FOR IMPLEMENTING THE METHOD

Abstract

An image reading apparatus including a shading correction mechanism that can be formed by fewer component parts than conventional ones, and is increased in the degree of freedom of design, thereby enabling reduction of the size and weight thereof. A contact glass guides an original to an image reading position. A glass holding member holds the glass. A line image sensor reads an image on the original conveyed to the image reading location, through the contact glass. A reference member is disposed at a location different from the image reading location on the contact glass. A moving mechanism relatively moves the line image sensor and the reference member so that the line image sensor can alternatively read the original conveyed to the image reading location and the reference member. A drive section externally drives the moving mechanism to move the line image sensor and/or 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 (:1), 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 flowchart of a shading correction data acquisition process executed by a CPU;

FIGS. 12A and 12B are vertical cross-sectional views showing a variation of the image reading unit, in which:

FIG. 12A shows a state during the original reading period; and

FIG. 12B shows a state during the reference member reading period;

FIG. 13 is a transverse cross-sectional view of the image reading unit shown in FIGS. 12A and 12B;

FIG. 14 is a transverse cross-sectional view of another variation of the image reading unit;

FIG. 15 is a schematic transverse cross-sectional view of an image reading apparatus according to a second embodiment of the present invention;

FIGS. 16A and 16B are schematic cross-sectional views of a front-side image reading section and a reverse-side image reading section appearing in FIG. 15, and component parts and elements associated therewith, in which:

FIG. 16A shows an original reading state or an original reading standby state; and

FIG. 16B shows a state during correction data acquisition;

FIGS. 17A to 17H are views schematically showing variations of the layout of reference members appearing in FIGS. 16A and 16B;

FIG. 18 is a side view showing the internal construction of a conventional image reading apparatus; and

FIGS. 19A and 19B are enlarged schematic cross-sectional views of an image reading section of a conventional image reading apparatus, in which:

FIG. 19A shows a state during the original reading period; and

FIG. 19B shows a state during the reference member reading period.

Claims

1. An image reading apparatus configured to read an image formed on a side of an original, while conveying the original, comprising: an image reading unit including a contact glass configured to guide the original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read the image on the original conveyed to the image reading location, through said contact glass, a reference member disposed at a location different from the image reading location on said contact glass, or on said glass holding member, such that an image of said reference member can be read by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so that said image sensor can alternatively read the original conveyed to the image reading location and said reference member; anda driving unit configured to drive said moving mechanism from the outside of said image reading unit to move at least one of said image sensor and said reference member,wherein said moving mechanism comprises a traveling member configured to move at least one of said image sensor and said reference member in a direction different from a longitudinal direction of said image reading unit.

2. An image reading apparatus according to claim 1, wherein said moving mechanism comprises said traveling member configured to hold said image sensor such that said image sensor can move between a first position for reading the image on the original and a second position for reading the image of said reference member, and an urging member configured to urge said traveling member such that said traveling member moves said image sensor to one of the first position and the second position, and wherein said driving unit comprises an operating member configured to drive said traveling member from the outside of said image reading unit, and a driving power source configured to cause said operating member to operate, andwherein said driving power source causes said operating member to operate for driving said traveling member urged by said urging member, whereby said image sensor is moved to the other of the first position and the second position.

3. An image reading apparatus according to claim 1, wherein said moving mechanism movably holds said reference member.

4. An image reading apparatus according to claim 1, wherein said traveling member is slidably engaged with said image sensor and is moved by said operating member in a direction substantially orthogonal to a direction in which said image sensor is moved, whereby said image sensor is moved to one of the first position and the second position, and in a state where said traveling member is moved in a direction in which traveling member is urged by said urging member, an end portion of said traveling member protrudes from said image reading unit.

5. An image reading apparatus according to claim 4, wherein said operating member is rotatably disposed such that said operating member comes into contact with said end portion of said traveling member protruding from said image reading unit, and when said driving power source causes said operating member to operate, said operating member presses said end portion of said traveling member into said image reading unit.

6. An image reading apparatus according to claim 5, wherein said operating member has at least one sloping surface formed on a portion thereof for contact with said traveling member.

7. An image reading apparatus according to claim 4, wherein said traveling member is a cam member.

8. An image reading apparatus according to claim 5, further comprising an original conveying unit configured to convey an original through a space enclosed by a first frame that can be turned around a pivot shaft and a second frame that supports the pivot shaft of said first frame, and a detect means configured to detect the turning motion of said first frame, and wherein said first frame holds one of said image reading unit and said driving unit, and said second frame holds the other of said image reading unit and said driving unit, control being provided to prevent a driving force of said operating member caused to operate by said driving power source from acting on said traveling member when the turning motion of said first frame is detected by said detect means.

9. An image reading apparatus according to claim 1, further comprising: a second image sensor configured to read an image formed on the other side of the original at a second image reading location;a second contact glass configured to guide the original to the second image reading location; anda second reference member that is configured to allow an image of said second reference member to be read by said second image sensor, andwherein said second image sensor reads an image formed on the second side of the original at said second image reading location, and for acquisition of shading correction data said moving mechanism moves said glass holding member which integrally holding said contact glass, said reference member and said second reference member, thereby to move said reference member to said image reading location and said second reference member to said second image reading location.

10. An image reading apparatus configured to read an image formed on an original, while conveying the original, comprising: an image reading unit including an image sensor configured to read an image of an object on a reading position of said image sensor, a contact glass configured to guide the original to a first position, a reference member disposed at a location different from the first position, and a moving mechanism configured to cause relative reciprocating motion varying relative position of the reading position of said image sensor and said reference member;a driving unit configured to drive said moving mechanism; anda control unit configured to control driving of said driving unit such that said reading position of said image sensor during a shading correction data acquisition period is set to a second position set on said reference member, and the reading position of said image sensor during an original image data reading period is set to said first position,wherein said control unit comprises:a moving-time read data acquisition means configured to acquire moving-time read data generated based on an output signal from said image sensor, while causing said relative reciprocating motion,a detection means configured to detect, based on the moving-time read data, that said reading position is at a boundary of a disposition area of said reference member,a driving amount acquisition means configured to acquire a driving amount of said driving unit required during a time period from a start of said relative reciprocating motion to a time point when said detection part detects that said reading position is at said boundary, anda driving amount calculation means configured to calculate, based on the acquired driving amount, a first driving amount for use in positioning the reading position of said image sensor to said first position and a second driving amount for use in positioning the reading position to said second position.

11. An image reading apparatus according to claim 10, wherein said moving mechanism moves at least one of said image sensor and a glass holding member holding said contact glass.

12. An image reading apparatus according to claim 10, wherein when the value of said moving-time read data changes across a predetermined threshold value, said detection means detects that the reading position of said image sensor is at the boundary of the disposition area of said reference member.

13. An image reading apparatus according to claim 12, further comprising a light source configured to illuminate the object on the reading position of the image sensor, and an amplifier means configured to amplify the output signal from said image sensor, and wherein said detection means increases or decreases at least one value of a illuminating light amount of said light source, an amplification factor of said amplifier means, and said threshold value.

14. An image reading apparatus according to claim 10, wherein when said detection means cannot perform the detection, calculation of the first and second driving amounts is suspended until the original is removed from the first position.

15. An image reading apparatus according to claim 10, wherein said control unit causes said moving-time read data acquisition means to perform an operation for acquiring the moving-time read data, over a time period during which there occur a first normal-direction moving-time detection of detecting the boundary of the disposition area of said reference member when the reading position of the image sensor is being moved in a normal direction of two directions of said reciprocating motion toward the reference member, an immediately subsequent reverse-direction moving-time detection of detecting the boundary when the reading position of the image sensor is being moved in a reverse direction of the two directions of said reciprocating motion, and an immediately subsequent second normal-direction moving-time detection of detecting the boundary when the reading position of the image sensor is being moved in the normal direction, and wherein the calculated second driving amount is equal to an intermediate value between a driving amount required for moving the reading position of the image sensor from said arbitrary initial position until occurrence of the first normal-direction moving-time detection, and a driving amount required for moving the reading position of the image sensor from said arbitrary initial position to occurrence of the immediately subsequent reverse-direction moving-time detection, andwherein the calculated first driving amount is equal to an intermediate value between a driving amount required for moving the reading position of the image sensor from said arbitrary initial position to the occurrence of the reverse-direction moving-time detection, and a driving amount required for moving the reading position of the image sensor from said arbitrary initial position until occurrence of the second normal-direction moving-time detection.

16. A shading correction method for an image reading apparatus configured to read an image formed on an original, while conveying the original, wherein the image reading apparatus comprises an image reading unit including an image sensor configured to read the image of an object on a reading position of said image sensor, a contact glass configured to guide the original to a first position, a reference member disposed at a location different from the first position, and a moving mechanism configured to cause relative reciprocating motion varying relative position of said reading position and said reference member, and a driving unit configured to drive the moving mechanism, the shading correction method comprising: a control step of controlling driving of the driving unit such that a reading position of the image sensor during a shading correction data acquisition period is set to a second position set on the reference member, and a reading position of the image sensor during an original image data reading period is set to said first position,wherein said control step comprises:a moving-time read data acquisition step of acquiring moving-time read data generated based on an output signal from said image sensor, while causing said relative reciprocating motion;a detection step of detecting, based on the moving-time read data, that said reading position is at a boundary of a disposition area of the reference member;a driving amount acquisition step of acquiring a driving amount of the driving unit required during a time period from a start of said relative reciprocating motion to a time point when said detection means detects that said reading position is at said boundary; anda driving amount calculation step of calculating, based on the acquired driving amount, a first driving amount for use in varying the reading position of said image sensor to said first position, and a second driving amount for use in varying the reading position of said image sensor to said second position.

17. A program for causing a computer to execute the shading correction method as claimed in claim 16.

18. An image reading apparatus comprising: an image reading unit including a frame formed with an opening;an image sensor configured to read an image on a reading position of said image sensor;a contact glass configured to guide an original to an original image reading location;a reference member disposed at a location different from the original image reading location;a moving mechanism configured to reciprocate the reading position of said image sensor between the original image reading location and a shading correction data acquisition position set on said reference member; anda driving unit configure to drive said moving mechanism, wherein said frame has said contact glass disposed in the opening, and has said image sensor, said moving mechanism, and said driving unit disposed therein.

19. An image reading apparatus configured to read an image formed on an original, while conveying the original, 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 formed on a first side of an original conveyed to the image reading location, through said contact glass, a reference member disposed at a location different from the image reading location on said contact glass or disposed at a location on said glass holding member, such that an image of said reference member can be read by said image sensor, and a moving mechanism configured to vary relative position of said image sensor and said reference member so that said image sensor can alternatively read the original conveyed to the image reading location and said reference member;a driving unit configured to drive said moving mechanism from the outside of said reading unit to move at least one of said image sensor and said reference member; anda second image reading unit including a second image sensor configured to read an image formed on a second side of the original in a second image reading location, a second contact glass configured to guide the original to the second image reading location, a second glass holding member holding said second contact glass, a second reference member disposed at a location different from the second image reading location on said second contact glass or disposed at a location on said second glass holding member, such that an image of said second reference member can be read by said second image sensor, and a second moving mechanism configured to relatively vary relative position of said second image sensor and said second reference member so that said second image sensor can read the original conveyed to the second image reading location and said second reference member, alternatively,wherein said driving unit is held by a first frame supporting said image reading unit or a second frame supporting said second image reading unit, and drives both said moving mechanism in said image reading unit and said second moving mechanism in said second image reading unit.

20. An image reading apparatus according to claim 19, wherein said image reading unit is movably supported by said first frame.

21. An image reading apparatus according to claim 19, wherein said second image reading unit is movably supported by said second frame.

22. An image reading apparatus configured to read an image formed on an original, while conveying the original, comprising: an image reading unit including a contact glass configured to guide the original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read the image on the original conveyed to the image reading location through said contact glass, a reference member disposed at a location different from the image reading location on said contact glass, or disposed at a location on said glass holding member, such that an image of said reference member can be read by said image sensor, and a moving mechanism configured to move said image sensor so that said image sensor can alternatively read the original conveyed to the image reading location and said reference member; anda driving unit configured to drive said moving mechanism from the outside of said image reading unit to move said image sensor.

23. An image reading apparatus according to claim 22, wherein said moving mechanism includes a cam member configured to hold said image sensor such that said image sensor can be moved between a first position for reading the image on the original and a second position for reading said reference member.