JP2007258960A - Image reading apparatus and unit thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus that can be provided with a simple and highly accurate shading correction mechanism whereby the apparatus can be downsized cost-effectively without needing complicated adjustment and alignment at assembling, and to provide an image reading unit thereof. <P>SOLUTION: The image reading unit 10 provided to the image reading apparatus 1 includes: a frame 12 part of an upper face of which opposed to a lower side of an original S is formed to be an opening and freely revolvably supporting a spindle 11a of a line image sensor 11 contained therein; a contact glass 15 fitted to and supported by the opening and for guiding the original at an original read position A; a color reference member 16 fixed inside the frame 12 and acting like a white reference; a gear 18 coupled to the spindle 11a via a friction mechanism; a drive gear 19 coupled to drive the gear 18; and a small-sized motor 20. The line image sensor 11, the gear 18, the drive gear 19, and the small-sized motor 20 are installed inside the frame 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image reading apparatus and an image reading unit thereof, and particularly to an image reading apparatus including an image reading unit having a shading correction mechanism and an image reading unit thereof.

  In general, an image reading apparatus that reads an image while conveying a document irradiates the conveyed document with a light source, and condenses reflected light from the document by a rod lens array or the like. Thereafter, the line image sensor or the like generates document image data by photoelectrically converting the collected reflected light. However, since the light source and the rod lens array have uneven light quantity and uneven sensitivity of the line image sensor, uniform document reading cannot be performed as it is. Therefore, conventionally, in order to enable uniform document reading, the white color reference member is read by the line image sensor, and the document image read by the line image sensor is corrected using the output value at that time. ing. This correction is generally performed after optimizing the light emission amount of the light source that irradiates the document and optimizing the amplification factor (gain) when amplifying the image signal output of the line image sensor. Hereinafter, a series of corrections for the line image sensor to uniformly read the image information of the document including the above-described adjustment of the light emission amount and gain will be referred to as “shading correction”.

  In addition, this type of image reading apparatus detects the boundary between the document and the background, the skew of the document, and the color of the member disposed on the back of the document in order to prevent the back side image of the document from showing through. Or a color other than white (generally black).

  Hereinafter, a shading correction mechanism of a conventional image reading apparatus will be described (for example, see Patent Document 1).

  7A and 7B are enlarged cross-sectional views of a shading correction mechanism of a conventional image reading apparatus. FIG. 7A shows a state when reading a document, and FIG. 7B shows a state when reading a color reference member.

  As shown in FIG. 7A, when reading a document, the shading sheet member 54 that is a white color reference member is separated from the platen roller 51 that is a black opposing member, the reading sensor 100, and the document conveyance path.

  The shading means includes a shading sheet member 54, an arm 56 as a swingable first swinging member, and a seat base 61 as a second swinging member swinging about a shaft 62 on the arm 56. Have The shading sheet member 54 is attached to the sheet base 61 so as to be deformable.

  The arm 56 is pulled by an elastic member 59 such as a tension spring and is in contact with the stopper 53. This is the standby position of the shading sheet member 54 during document conveyance.

  One end of a gear 58 is attached to the plunger (suction member) 52 of the solenoid 55. When the solenoid 55 is turned on, the plunger 52 is sucked, and the gear 58 rotates around the shaft 60 in the clockwise direction. In conjunction with this, the arm 56 engaged with the gear 58 rotates counterclockwise around the shaft 57.

  On the other hand, when the platen roller 51, the reading sensor 100 and the document conveyance path come into contact with the shading sheet member 54 and the rotation in the counterclockwise direction is completed, as shown in FIG. The member can be read.

  That is, when the solenoid 55 is turned on, the shading sheet member 54 enters the gap between the platen roller 51 and the reading sensor 100 via the gear 58, the arm 56, and the sheet base 61.

  In this state, when the shading correction data is acquired and then the solenoid 55 is turned OFF, the shading sheet member 54 returns to the standby position by pulling the elastic member 59.

Note that there are some members that use a plate-like member such as a guide plate instead of the platen roller 51 as an opposing member of the reading sensor 100. In some cases, the reading sensor 100 is moved instead of moving the shading sheet member 54 when acquiring shading correction data.
JP 2005-102017 A

  However, in the above conventional image reading apparatus, the mechanism for moving the color reference member is complicated, which causes an increase in cost. In addition, since the reading sensor and the mechanism for moving the color reference member are separate units, there is a problem in that the adjustment and positioning of the components are necessary at the time of assembly, and the assembly workability is poor.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus capable of reducing the size of the apparatus while suppressing an increase in cost, and enabling a simple and highly accurate shading correction mechanism without requiring complicated adjustment and alignment during assembly work. And an image reading unit thereof.

  In order to achieve the above object, an image reading apparatus according to claim 1 is provided with an image reading unit and reads an image formed on a document, wherein the image reading unit includes a casing having an opening; A reading sensor that reads an image at a sensor facing position, a contact glass that guides the document to the document reading position, a color reference member that is installed at a position different from the document reading position, and the sensor facing position that reads the document A movement mechanism that reciprocates between a position and a shading correction data acquisition position on the color reference member, and a driving unit that drives the movement mechanism, and the housing includes the contact glass in the opening, The reading sensor, the moving mechanism, and the driving unit are installed therein.

  According to the present invention, the image reading unit includes a housing having an opening, a reading sensor that reads an image at a sensor facing position, a contact glass that guides the document to the document reading position, and a position different from the document reading position. A color reference member installed on the color reference member, a moving mechanism for reciprocally moving the sensor facing position between a document reading position and a shading correction data acquisition position on the color reference member, and a driving means for driving the moving mechanism, The housing has a contact glass in its opening and a reading sensor, moving mechanism, and driving means in its interior, enabling cost reduction and miniaturization of the device, and complicated adjustments during assembly work. It does not require alignment and enables a simple and highly accurate shading correction mechanism.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an overall schematic diagram of an image reading apparatus according to a first embodiment of the present invention.

  In FIG. 1, an image reading apparatus 1 includes a pickup roller 2 that picks up a document S, a feeding roller 3 that feeds the document S picked up by the pickup roller 2 into the apparatus, and one sheet of the picked-up document S. And a separation roller 4 for separating them one by one. Further, the image reading apparatus 1 includes a registration roller pair 5 that conveys the document S while correcting the skew of the document S, an image reading unit 9 that reads image information on the front surface of the document S, and image information on the back surface of the document S. And an image reading unit 10. Further, the image reading apparatus 1 includes a pair of conveying rollers 7 disposed on the downstream side of the image reading units 9 and 10.

  The image reading apparatus 1 includes an upper frame 81 and a lower frame 82, and the upper frame 81 is rotatable about a rotation shaft 81a. In addition, the image forming apparatus 1 can be manually opened and closed in order to remove the document staying in the image reading apparatus 1 when a paper jam or the like of the conveyed document occurs.

  With the above configuration, the image reading apparatus 1 operates as follows when reading an image of the document S. First, as will be described in detail later, each of the image reading units 9 and 10 converts reflected light from the color reference member into a reading signal by a reading sensor (line image sensor). A control unit (not shown) converts this read signal into digital read data by an A / D conversion unit (not shown), generates shading correction data from this read data, and stores it for each pixel. This shading correction data acquisition operation is performed when the image reading apparatus is activated or when reading operation is started.

  Thereafter, the document S is taken into the apparatus by the pickup roller 2 and the feeding roller 3 and separated one by one by the separation roller 4. The document S is sandwiched between the registration roller pair 5 and the conveyance roller pair 7 and conveyed, and images on the front and back surfaces thereof are read by the image reading units 9 and 10. At the time of image reading, the output of the reading sensor in the image reading units 9 and 10 is subjected to shading correction with reference to shading correction data described later. After the image is read, the document S is discharged outside the apparatus 1 while being nipped and conveyed by the conveyance roller pair 7.

  2 and 3 are cross-sectional views showing the configuration of the image reading unit 10 in FIG. Hereinafter, since the image reading units 9 and 10 have the same configuration, the image reading unit 10 will be described.

  2 and 3, the image reading unit 10 has a part of the upper surface facing the lower surface of the document S as an opening, and a frame that rotatably supports the support shaft 11a of the line image sensor 11 accommodated therein. 12 is provided. The line image sensor 11 includes an LED as a lighting unit and a selfoc lens array.

  Further, the image reading unit 10 includes a substrate 13 that operates the line image sensor 11 and a flat cable 14 that connects the line image sensor 11 and the substrate 13. The image reading unit 10 includes a contact glass 15 that is fitted and held in the opening of the frame 12 and guides the document at the document reading position A. Further, the image reading unit 10 includes a color reference member 16 serving as a white reference fixed inside the frame 12, and a casing member 17 that holds the substrate 13 from the lower side of the frame 12 and casing the inside. Further, the image reading unit 10 includes a gear 18 that is connected to the support shaft 11 a via a friction mechanism, a drive gear 19 that is connected to drive the gear 18, and a small motor 20 inside the frame 12.

  In the above configuration, when the small motor 20 is rotated forward in a state where the sensor facing position of the line image sensor 11 is at the position (original image reading position A) of FIG. 2A, the gear 18 rotates. This rotation is transmitted to the support shaft 11a of the line image sensor 11 through a friction plate 21 and a pressing spring 22 as a friction mechanism, thereby rotating the line image sensor 11. Thereafter, when the sensor facing position reaches the position shown in FIG. 2B (shading correction data acquisition position) with the support shaft 11a as a fulcrum, the rotation of the line image sensor 11 is stopped.

  The line image sensor 11 photoelectrically converts reflected light received from the color reference member 16 at the shading correction data acquisition position, and reads data based on the sensor output signal (read signal) after the photoelectric conversion as shading correction data for each pixel. Remember.

  After the shading correction data is acquired, when the small motor 20 is rotated in the reverse direction, the line image sensor 11 rotates in the reverse direction, and the sensor facing position returns to the document reading position A in FIG.

  The line image sensor 11 receives reflected light from the original sequentially conveyed to the original reading position A through the contact glass 15, and stores the sensor output value after photoelectrically converting the reflected light as original image data for each pixel. .

  Further, the frame 12 is formed with stopper portions 12a and 12b for restricting the rotation of the line image sensor 11 so as to reciprocate the sensor facing position between the document reading position A and the shading correction data acquisition position. Even if the amount of rotation of the motor 20 is not controlled with high accuracy by the stopper portion and the friction plate 21, the sensor facing position of the line image sensor 11 is surely stopped at the document reading position A and the shading correction data acquisition position. be able to.

  The line image sensor 11 is configured such that the distance to the color reference member 16 at the shading correction data acquisition position is equal to the optical distance to the original surface at the original reading position A (with glass thickness correction of the contact glass 15 between them). Is arranged. This is to make the reading conditions of the line image sensor 11, that is, the focal position and the illumination light amount equal at the document reading position and the shading correction data acquisition position.

  Further, instead of setting the arrangement for equalizing the optical distance as described above, the difference in the amount of reflected light due to the difference in the optical distance may be corrected. The reading of the color reference member is possible even if it is not in the in-focus position, and the position shifted from the in-focus position is also included in the sensor facing position.

  Further, since the small motor 20 is provided inside the frame 12, the image reading unit 10 can be reliably sealed.

  Further, if the support shaft 11a of the image reading unit 10 is structured so as not to be exposed to the outside of the frame 12, the sealing degree can be further improved.

  4 and 5 are cross-sectional views showing the configuration of the image reading unit according to the second embodiment of the present invention.

  Since the image reading unit 10a according to the present embodiment has basically the same structure as the image reading unit 10 described above, the same members are denoted by the same reference numerals, and redundant description is omitted. .

  4 and 5, the image reading unit 10 a is installed on the upper surface of the frame 12 ′ in which the entire upper surface is opened and the line image sensor 11 is accommodated, and the entire surface is sealed. A glass holding member 24. The image reading unit 10a includes a contact glass 15a that is held by the glass holding member 24 and guides the document at the document reading position A, and the image reading unit 10a includes a color reference member 16a that serves as a white reference. Further, the image reading unit 10 a is connected to the rectilinear cam 21 that moves the line image sensor 11 in a direction orthogonal to the main scanning direction, a tension spring 22 that applies a biasing force to the rectilinear cam 21, and the rectilinear cam 21. And a solenoid 23.

  The color reference member 16a is installed at a position shifted from the document reading position A on the upper surface (outside of the frame 12 ') of the contact glass 15a by adhesion, sticking with tape, painting or printing. The color reference member 16a may be provided on the lower surface of the contact glass 15a (inside the frame 12 ').

  The line image sensor 11 has a protrusion 11a ', and the protrusion 11a' is fitted into the long hole 12b 'of the frame 12' to restrict movement in the main scanning direction.

  In FIG. 5, a rectilinear cam 21 includes cam grooves 21a and 21b in which the projections 11a ′ and 11b of the line image sensor 11 are fitted, and elongated holes 21c and 21d in which the projections 12c and 12d of the frame 12 ′ are fitted. And a locking portion 21e for locking the tension spring 22. The rectilinear cam 21 is urged in the direction of arrow B when the tension spring 22 is locked by the locking portion 12e. Furthermore, one end of the rectilinear cam 21 is connected to the plunger 23 a of the solenoid 23.

  In the above configuration, when the solenoid 23 is excited and the plunger 23a is attracted by exciting the solenoid 23 in a state where the sensor facing position of the line image sensor 11 is at the position (original image reading position A) of FIG. Move in the direction. The line image sensor 11 moves in the direction of arrow D due to the movement of the rectilinear cam 21. Thereafter, when the sensor facing position reaches the position shown in FIG. 4B (shading correction data acquisition position), the movement of the line image sensor 11 stops.

  The line image sensor 11 photoelectrically converts the reflected light received from the color reference member 16a at the shading correction data acquisition position, and stores read data based on the sensor output signal after the photoelectric conversion as data for shading correction for each pixel. To do.

  After the shading correction data is acquired, when the solenoid 23 is de-energized, the rectilinear cam 21 is returned by the tension spring 22, and the sensor facing position returns to the document reading position A accordingly.

  The image reading unit 10a moves the line image sensor 11 in the sub-scanning direction orthogonal to the main scanning direction. In general, since the reading width of the line image sensor 11 in the sub-scanning direction is very small, the amount of movement can be reduced.

  In addition, since the solenoid 23 is provided inside the frame 12 ', the image reading unit 10a can be reliably sealed.

  In the present embodiment, only the line image sensor 11 is moved. However, only one of the color reference member 16a, the glass holding member 24, the contact glass 15a, or some of them is moved. May be.

  FIG. 6 is a cross-sectional view showing the configuration of an image reading unit according to the third embodiment of the present invention.

  Here, the above-described image reading unit 10a uses a solenoid as a driving means for moving the rectilinear cam 21 connected to the line image sensor 11. On the other hand, the image reading unit 10b according to the present embodiment uses Biometal (registered trademark) 28, which is a kind of shape memory alloy, as the driving means. Except for the difference in the driving means, the image reading unit 10a and the image reading unit 10b basically have the same structure. Therefore, the same members are denoted by the same reference numerals, and redundant description is omitted. .

  In FIG. 6, the driving means of the image reading unit 10b is a metallic fiber actuator provided with a biometal 28. When an electric current is applied, about 5% of the total length contracts, and when energization is stopped, the original length Return to Thereby, it is excellent in responsiveness, can shrink | contract easily with a low voltage, and can obtain a comparatively big generated force.

  In the image reading unit 10b, a shaft 21f is integrally formed at one end of the rectilinear cam 21, and a pulley 25 is rotatably supported on the shaft 21f. Terminals 26 and 27 are provided in the frame 12. The biometal 28 is wound around the pulley 25 and both ends thereof are fixed to the terminals 26 and 27.

  In the above configuration, when the voltage from the external control circuit 29 is applied to the terminals 26 and 27 in the image reading unit 10b in a state where the sensor facing position of the line image sensor 11 is at the document reading position A (not shown), biometal 28 contracts. As a result, the rectilinear cam 21 is pulled in the arrow C direction via the pulley 25. The line image sensor 11 is moved in the direction of arrow D by the movement of the rectilinear cam 21 accompanying this pulling. Thereafter, when the sensor facing position becomes the shading correction data acquisition position, the movement of the line image sensor 11 stops.

  The line image sensor 11 photoelectrically converts the reflected light received from the color reference member 16 at the shading correction data acquisition position, and stores the sensor output value after the photoelectric conversion for each pixel as data for shading correction.

  After the shading correction data is acquired, when the energization of the control circuit 29 is turned off, the biometal 28 extends to the original length. As a result, the rectilinear cam 21 is returned by the tension spring 22, and the sensor facing position returns to the document reading position A accordingly.

  In the present embodiment, the biometal 28 is wound around the pulley 25, so that the tension generated when the biometal 28 contracts is doubled. However, when there is sufficient tension generated in the biometal 28, the biometal 28 and the straight cam 21 may be directly connected without using the pulley 25.

  In the present embodiment, only the line image sensor 11 is moved when performing shading correction, but only the color reference member 16a or both may be moved.

  In addition, the driving means for moving the line image sensor 11 or the color reference member 16a may be other than the means shown in the first to third embodiments. For example, an actuator such as a piezoelectric element or a magnetostrictive element may be used.

1 is an overall schematic diagram of an image reading apparatus according to a first embodiment of the present invention. 2A and 2B are longitudinal sectional views illustrating the configuration of the image reading unit in FIG. 1, in which FIG. 1A illustrates a state during reading of a document, and FIG. 2B illustrates a state during reading of a color reference member. FIG. 2 is a cross-sectional view illustrating a configuration of an image reading unit in FIG. 1. 4A and 4B are longitudinal sectional views showing a configuration of an image reading unit according to a second embodiment of the present invention, where FIG. 5A shows a state when reading a document, and FIG. 5B shows a state when reading a color reference member. Show. 4A and 4B are cross-sectional views showing a configuration of an image reading unit according to a second embodiment of the present invention, where FIG. 5A shows a state when reading a document, and FIG. 5B shows a state when reading a color reference member. Show. It is a cross-sectional view showing a configuration of an image reading unit according to a third embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a shading correction mechanism of a conventional image reading apparatus, where (a) shows a state when reading a document, and (b) shows a state when reading a color reference member.

Explanation of symbols

S Document 1 Image reading device 9, 10 Image reading unit 11 Line image sensor 12 Frame 15 Contact glass 16 Color reference member 20 Small motor 23 Solenoid 28 Biometal

Claims (9)

In an image reading apparatus that includes an image reading unit and reads an image formed on a document,
The image reading unit includes:
A housing having an opening, a reading sensor for reading an image at a sensor facing position, a contact glass for guiding the document to the document reading position, and a color reference member installed at a position different from the document reading position; A moving mechanism for reciprocally moving the sensor facing position between the document reading position and a shading correction data acquisition position on the color reference member; and a driving means for driving the moving mechanism;
The image reading apparatus according to claim 1, wherein the casing is provided with the contact glass in the opening, and the reading sensor, the moving mechanism, and the driving unit in the opening.   The image reading apparatus according to claim 1, wherein the color reference member is installed on the contact glass.   The image reading apparatus according to claim 1, wherein the color reference member is installed outside the contact glass inside the housing.   The image reading apparatus according to claim 1, wherein the contact glass is fitted into the opening.   The image reading apparatus according to claim 1, wherein the contact glass is held by a glass holding member installed on one surface of the casing.   The image reading apparatus according to claim 5, wherein the moving mechanism moves at least one of the reading sensor, the color reference member, the contact glass, and the glass holding member.   The image reading apparatus according to claim 1, wherein the image reading unit is hermetically sealed. A document transport mechanism for transporting the document to the image reading unit;
8. The apparatus according to claim 1, wherein the reading sensor sequentially reads an image formed on the document at the document reading position while the document is transported by the document transport mechanism. 9. Image reading device.   An image reading unit provided in the image reading apparatus according to claim 1.

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