JP2004336425A - Picture reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a picture reader by which stray light incidence on a lens is suppressed without providing a light shielding means, including a shutter, and exact black correction data for correcting a picture read by means of a photoelectric conversion element is obtained. <P>SOLUTION: White correction data are obtained by light irradiation from a lamp 34 and by imaging reflected light from a white standard board 15 on a CCD (Charge Coupled Device) 33. In addition, external stray light is simply interrupted to form the data read under a state lighting no lamp 34 to the black correction data. Correction processing is applied to the picture of an original read by the CCD 33 based on the white correction data and the black correction data read by the CCD 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image reading apparatus that moves an optical unit mounted on a carriage relative to a document and obtains image data by scanning the document, and more particularly to an improvement in a method of reading black correction data.
[0002]
[Prior art]
Generally, in an image reading apparatus provided in a copying machine or the like, a carriage provided with a reflecting mirror is moved along an original placed on a platen glass, and an image of the original illuminated by a lamp is reflected by the reflecting mirror, and a lens is provided. The light is guided to a light-receiving element such as a CCD via a CCD (see, for example, Patent Document 1).
[0003]
Further, in this type of image reading apparatus, correction data is obtained at a predetermined timing because of unevenness of illumination light and variations in characteristics of each pixel of a light receiving element such as a CCD. In the image reading device described above, the light receiving element reads the black correction data, opens the shutter, and turns on the lamp with the shutter placed in front of the lens to block light or turn off the lamp. In this state, the light receiving element reads the white correction data, sets a correction value for each pixel of the light receiving element from the data, and performs a correction process on the image data read by the light receiving element. By this correction processing, it is possible to obtain the copy image data faithful to the original without the streak and the unevenness on the copy image due to the non-uniformity of the illumination light and the characteristic variation of each pixel of the light receiving element.
[0004]
By the way, the present applicant, instead of the mirror scan method as described above, includes a CCD together with a rod lens array (a lens in which a large number of gradient index lenses are arranged, also called a SELFOC lens) on a carriage, and a reflecting mirror. We have developed an image reading device that eliminates the need. In this image reading apparatus, the optical axis of the rod lens array is directed vertically (to the platen glass side), and light passing through the rod lens array forms an image directly on the light receiving section of the CCD.
[0005]
[Patent Document 1]
JP 10-257251 A
[Problems to be solved by the invention]
By the way, the rod lens array moves together with the carriage, is relatively long over the entire length of the carriage, and is close to the platen glass. For this reason, it is difficult to provide a shutter in this rod lens array to perform black correction, because the shutter becomes large and it is difficult to open and close. Therefore, it is conceivable to read the black correction data with the lamp turned off without using the shutter. However, depending on the installation environment, for example, stray light from the outside such as indoor lighting may cause appropriate black correction data to be read. There is a problem that it is difficult to obtain.
[0007]
Therefore, the present invention can suppress the incidence of stray light on a lens without providing a light-shielding unit such as a shutter, and can obtain accurate black correction data for correcting an image read by a photoelectric conversion element. It is intended to provide a reading device.
[0008]
[Means for Solving the Problems]
The image reading apparatus of the present invention includes a platen glass on which a document is placed, a carriage having a light source for irradiating the document with light, and running along the platen glass, and light reflected by the document being imaged on a light receiving surface A platen glass is provided in the image reading apparatus, comprising: a photoelectric conversion element configured to convert the amount of electricity into a quantity of light corresponding to the amount of light on the light receiving surface; and control means for controlling travel of the carriage and processing an image read by the photoelectric conversion element. A white reference portion is provided at an end of the control device, and at a position where the carriage reads the white reference portion, the light source is turned on, the data read by the photoelectric conversion element is set as white correction data, the light source is turned off, and the photoelectric conversion element is turned off. Is characterized in that the data read by the computer is black correction data.
[0009]
In the image reading device having the above configuration, the light source is turned on while moving the carriage at a position where the white reference portion is read, the reflected light from the white reference portion is imaged on the photoelectric conversion element, and the white correction data is output. read. Further, the light source is turned off with the carriage stopped, and the black correction data is read. Then, a correction value is set for each pixel of the light receiving element from the white correction data and the black correction data, and correction processing is performed on the image data read by the light receiving element. Therefore, accurate black correction data can be obtained without using a light-blocking shutter. Since it is sufficient to provide a white reference portion at the end of the platen glass, it can be realized with a simple and inexpensive configuration. In addition, by blocking external stray light by the white reference portion so as not to enter the carriage, accurate black correction data can be stably obtained without being affected by stray light.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1. FIG. 1 is a perspective view showing an image reading apparatus according to an embodiment, and FIG. 2 is a side sectional view as viewed from a direction A in FIG. 1. This image reading apparatus is applied to, for example, a copying machine or a facsimile. Have been. In FIGS. 1 and 2, reference numeral 1 denotes a housing constituting an outer shell of the image reading apparatus. The housing 1 is a rectangular box-shaped body, the upper surface of which is open and a platen glass 10 is attached. A CVT glass 11 is arranged at one end of the housing 1 and next to the platen glass 10 with a document guide 14 interposed therebetween. The CVT glass 11 is supported by the document guide 14 and the housing 1.
[0011]
FIG. 3 shows an end on the side on which the CVT glass 11 is arranged. In FIG. 3, reference numeral 2 denotes a cover (omitted in FIGS. 1 and 2). The cover 2 is openable and closable so as to approach and separate from the platen glass 10 and the CVT glass 11. The cover 2 is automatically fed with a sheet tray 20 on which documents are set and the documents set on the sheet tray 20 one by one, and discharged onto the cover 2 from the discharge port 21 via the upper surface of the CVT glass 11. A paper feed mechanism 22 is provided. The paper feed mechanism 22 includes a transport drum 22a that rotates clockwise in FIG.
[0012]
As shown in FIG. 3, the document guide 14 includes a guide piece 14 a that guides the document from the upper surface of the CVT glass 11 to the discharge port 21 by the paper feed mechanism 22, a flat plate portion 14 b that covers the upper surface of the end of the platen glass 10, have. The guide piece 14a protrudes upward, has a triangular cross section, and has a curved document guide surface formed on the CVT glass 11 side.
[0013]
On the bottom surface of the housing 1, a pair of rails 13 extending in the left-right direction in FIG. The carriage 3 is slidably supported on the rail 13 in the longitudinal direction. As shown in FIG. 1, three buttons 30 and 31 (only two buttons are shown in FIG. 2) protruding upward are attached to the carriage 3. The buttons 30 and 31 are made of a synthetic resin such as plastic having a small coefficient of friction, and the upper end thereof has a substantially spherical shape in order to reduce frictional resistance with the platen glass 10 and the like.
[0014]
A rod lens array (Selfoc lens) 32 whose optical axis is directed vertically is attached to the upper surface of the carriage 3, and below the rod lens array 32, light received by the light passing through the rod lens array 32 is imaged. A CCD (photoelectric conversion element) 33 having a section is arranged. The carriage 3 is provided with a lamp (light source) 34 for irradiating light obliquely upward. Further, a slider 35 that slides on the rail 13 is attached to the lower surface of the carriage 3. The slider 35 is attached to the frame of the carriage 3 via a compression spring 35a, whereby the carriage 3 is urged upward, and the upper end surfaces of the buttons 30, 31 are placed on the platen glass 10 and the CVT glass 11, respectively. Is pressed down. The carriage 3 configured as described above is caused to travel on the rails 13 by a drive mechanism 4 described below.
[0015]
As shown in FIG. 3, both ends of a wire 40 are connected to the carriage 3, and the wires 40 are connected to both ends of the carriage 1 inside the housing 1 via pulleys (not shown) arranged at four corners of the housing 1. It is stretched and locked at both ends of the carriage 3. The wire 40 is wound a plurality of times around a driving pulley 41 disposed between the pulleys, and the driving pulley 41 is attached to a rotating shaft of a motor 42 such as a stepping motor.
[0016]
In FIG. 3, reference numeral 5 denotes a controller (control means). The controller 5 controls the rotation of the motor 42 to move the position and speed of the carriage 3 according to a program, and performs control and processing such as transferring the read image data to the image processing unit.
[0017]
As shown in FIG. 1, an original reading range is set on a platen glass 10 by a resist plate 9. The resist plate 9 is an inverted L-shaped thin plate having a vertical plate portion 9a and a horizontal plate portion 9b which are orthogonal to each other, and is fixed on a platen glass 10, and an original is formed by an intersection of both plate portions 9a and 9b. It is positioned by matching the right inner corner of the right back corner.
[0018]
As shown in FIG. 4, a concave portion is formed on the lower surface of the vertical plate portion 9a of the resist plate 9, and a white reference plate (white reference portion) 15 is fitted and fixed in the concave portion. The white reference plate 15 extends over substantially the entire length of the vertical plate portion 9 a, at least the lower surface thereof is white, and the white lower surface is in close contact with the upper surface of the platen glass 10.
[0019]
2. Next, an operation of the image reading apparatus having the above-described configuration will be described.
a. When reading the platen document, the document is placed on the platen glass 10 and positioned by the resist plate 9, and then the start button on the operation panel is pressed. Then, the motor 43 rotates, and the carriage 3 travels from the origin position at the left end in FIG. 2 to the right in FIG. Then, for example, when the carriage 3 comes to the position just before the document guide 14 and reading is completed, the motor 43 rotates in the reverse direction, and the carriage 3 returns to the origin position.
[0020]
While the carriage 3 is traveling to the right in FIG. 2, the lamp 34 is turned on and the image of the original is incident on the rod lens array 32. The light passing through the rod lens array 32 forms an image at the light receiving portion of the CCD 33. I do. Then, the CCD 33 outputs image data corresponding to the received light to the controller 5, and the controller 5 transfers the input image data to the image processing unit.
[0021]
b. Next, when an original is set on the paper tray 20, the controller 5 causes the carriage 3 to travel from the origin position to the right in FIG. 2 so that the rod lens array 32 is positioned immediately below the CVT glass 11. Stop to position. This position is where the image of the original is read by the CCD 33 of the carriage 3 when the original sent from the paper tray 20 by the paper feed mechanism 22 passes over the upper surface of the CVT glass 11. Documents set on the paper tray 20 automatically travel one by one from the upper surface of the CVT glass 11 along the document guide surface of the guide piece 14 a of the document guide 14, and are discharged from the discharge port 21.
[0022]
During the automatic document feed, the lamp 34 is turned on, the image of the document passing through the upper surface of the CVT glass 11 is incident on the rod lens array 32, and the light passing through the rod lens array 32 is imaged by the light receiving section of the CCD 33. I do. Then, the CCD 33 outputs image data corresponding to the received light to the controller 5, and the controller 5 transfers the input image data to the image processing unit.
[0023]
c. At the time of reading the black correction data, the cover 2 is closed, the lamp 34 is turned on, and as shown in FIG. 4, the position where the rod lens array 32 is disposed almost immediately below the center of the white reference plate 15, that is, the position where the white reference plate 15 is read. Then, the carriage 3 is moved. The light of the lamp 34 is reflected by the white lower surface of the white reference plate 15, and the reflected light is incident on the rod lens array 32 and is imaged by the CCD 33. Thereby, white correction data is obtained. Next, the carriage 3 is stopped at the position where the white reference plate 15 is read, and the lamp 34 is turned off. At this time, light formed by the CCD 33 is obtained as black correction data. The white correction data and black correction data read by the CCD 33 are input to the controller 5, and the controller 5 corrects the image of the document read by the CCD 33 based on the white correction data and the black correction data. Reading of such white correction data and black correction data is repeated at regular intervals, for example, while the power is on.
[0024]
At the time of reading the black correction data, the rod lens array 32 is disposed immediately below the white reference plate 15 to block stray light from the outside with the white reference plate 15 and its holding member, and the cover 2 is closed. The CCD 33 does not receive external stray light. Therefore, accurate black correction data can be obtained without using a light-blocking shutter. Further, since the white reference plate 15 may be disposed at the end of the platen glass 10, the black correction data can be obtained with a simple and inexpensive configuration.
[0025]
【The invention's effect】
As described above, according to the present invention, black correction data is obtained by blocking external light by the white reference portion provided at the end of the platen glass. There is an effect that incidence can be suppressed and accurate black correction data can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view of an image reading apparatus according to an embodiment of the present invention.
FIG. 2 is a side sectional view of the image reading apparatus viewed from a direction A in FIG.
FIG. 3 is a side sectional view showing a right end portion of FIG. 2;
FIG. 4 is a side sectional view showing a left end portion of FIG. 2;
[Explanation of symbols]
3: Carriage 5: Controller (control means)
10: Platen glass 15: White reference plate (white reference portion)
33 ... CCD (photoelectric conversion element)
34 ... Lamp (light source)

Claims (1)

A platen glass on which the original is placed,
A carriage having a light source for irradiating the original with light and running along the platen glass;
A photoelectric conversion element that forms an image on a light receiving surface of light reflected by the document and converts the light into an amount of electricity according to the amount of light on the light receiving surface;
Control means for controlling the travel of the carriage and processing the image read by the photoelectric conversion element,
A white reference portion is provided at an end of the platen glass,
At the position where the carriage reads the white reference portion, the control unit turns on the light source, sets the data read by the photoelectric conversion element as white correction data, turns off the light source, and reads the data by the photoelectric conversion element. An image reading apparatus wherein data is black correction data.

Images