JPH0352377A - Picture reader - Google Patents

Abstract

PURPOSE:To always attain accurate shading correction and to attain miniaturization by providing movably a correction reference face to obtain the correction of a picture signal. CONSTITUTION:A correction reference face W to correct a picture signal is provided between a carrier path and an optical conversion means 11. Moreover, it is desired to provide the correction reference face W onto a transparent guide base 16. Furthermore, it is also desired that the correction reference face W is to be moved by a torque delivered from the carrier means carrying an original. Then shading correction is always attained accurately by providing the movable correction reference face W to the picture reader and miniaturization is attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an image reading device used as a facsimile reading unit, an image scanner, etc. Regarding image reading devices. [Prior Art] As a conventional image reading device, one having a function of performing shading correction is known.

Shading correction refers to correcting variations in the threshold density between white pixels and black pixels caused by variations in the light intensity distribution of the light source and non-uniformity in the sensitivity of the photoelectric conversion element. This is performed by reading a surface (hereinafter referred to as a white reference surface) and correcting variations in density recognized by each photoelectric conversion element.

Conventionally, the following methods have been known as specific means for performing shading correction, for example. ■When shipped from the factory, read the white reference plane for each device and store the obtained correction values in the device's internal memory. ■When reading a document, it is assumed that the first line of the document is all white pixels, and this is read as a white reference plane. (2) In an image reading device in which a conveyance roller is provided opposite a lens system at an image reading position, the conveyance roller is shaped like a white roller, and the surface of the roller is used as a white reference surface to read a document before it is brought in.

■For image reading devices that do not have a conveyance roller at the image reading position, as shown in Figure 11, a white reference surface (white tape, white paint, etc.) is provided at the image reading position.
This is read before the manuscript is brought in. [Problems to be Solved by the Invention] However, when shading correction is performed using the above-mentioned conventional techniques, the following technical problems must be solved: There was an issue. ■If the correction values are stored in the device's internal memory in advance, it is not possible to deal with changes in the light intensity distribution of the light source over time. image quality will deteriorate.

■If it is assumed that the first line of the original is all white pixels when reading the original 'ip4, correction cannot be performed if there are black pixels in the first line. ■If the surface of the conveyance roller is used as a white reference surface, the surface of the conveyance roller is likely to get dirty, and this dirt may make it impossible to perform accurate correction, resulting in a decrease in image quality. ■When a white reference surface is provided at the image reading position, the document passes over the white reference surface, so the white reference surface is easily soiled, and the durability of the white reference surface can be improved. There is nothing. The present invention has been made in view of the above technical problems, and it is an object of the present invention to provide an image reading device that can always perform accurate shading correction and can be miniaturized. [Means for Solving the Problems] The image reading device of the present invention includes: a light irradiation device for illuminating a document to be read; a photoelectric conversion device for reading an image of the document; and a photoelectric conversion device for transporting the document. An image reading device having a conveying means, characterized in that a correction reference surface for obtaining correction of an image signal is provided movably. Further, the image reading device of the present invention includes: a light irradiation device for illuminating a document to be read; a photoelectric conversion device for reading an image of the document; and a conveyance device for conveying the document. The reading device is characterized in that a correction reference plane for correcting the image signal is provided between the transport path defined by the transport means and the light conversion means.

In the above feature, it is desirable that the correction reference plane be provided on a transparent guide substrate.

Furthermore, in the above feature, it is preferable that the correction reference surface be configured to be moved by a driving force transmitted from a conveying means for conveying the original. [Function] According to the present invention, since the image reading device is provided with a movable white reference plane, it is possible to provide an image reading device that can always perform accurate shading correction and can be miniaturized. becomes.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic cross-sectional view showing the structure of an image reading device according to a first embodiment of the present invention. FIG. 2 is a schematic bottom perspective view showing a contact type 1-magnification image sensor unit which constitutes a main part of the image reading device shown in FIG.'s1. Figure 3(a) is a schematic cross-sectional view of the contact type 1x image sensor unit shown in Figure 2, and Figure 3(b) is the contact type 1x image sensor unit shown in Figure 3(a). It is a schematic cross-sectional view showing the state of the sensor unit when the original 11M is removed. Further, FIG. 4 is a schematic cross-sectional view showing the configuration of the driving section of the image reading device of this embodiment. In each figure, 11 is a photoelectric conversion element array as photoelectric conversion means, 12 is a SELFOC lens array, and 13 is an LED array as light irradiation means, which are fixed and housed in housings 14 and 15, respectively. is a transparent substrate made of glass or the like. The housing 15 is provided with a convex pedestal for supporting the transparent substrate 16,
Furthermore, a step is provided for abutting both ends of the transparent substrate 16 in the document transport direction. Here, the transparent substrate 16
The length in the document conveyance direction is shorter than the length between the abutment surfaces. In other words, the transparent substrate 16 is structured to slide on the pedestal in the document transport direction. Further, a white reference surface W is provided on a part of the transparent substrate, and when the transparent substrate 16 abuts in the document conveyance direction, the white reference surface W is formed into a line image (for example, by painting white, pasting a white sticker, etc.). When one line reading area of the sensor is avoided in the direction opposite to the light source with respect to the reading line, and conversely, when the transparent substrate 16 hits in the opposite direction to the document conveyance direction,
It is configured to be located on the reading line of the line image sensor. The image reading apparatus of this embodiment has a document tray 30 on which a large number of documents S are stacked, as shown in FIG. xi. A gear 3 is connected to a motor 35 on the downstream side of the tray 30.
3 (see FIG. 4) is rotatably supported, and a separation pad 6 is attached to the lower side of the feed roller 23 by a spring 4 whose one end is in contact with a base 28. The feeding roller 23 is pressed and biased. Further, a support plate (not shown) is rotatably supported by the shaft 24 of the feeding roller 23, and a shaft 26 is supported by the support plate.

Furthermore, a pickup roller 25 is configured to be driven by a belt (not shown) on the shaft 26 from the feeding roller 23 . Further, a sheet edge sensor 7 for detecting the edge of the document S is disposed downstream of the separation pad 6. 21 is a conveyance roller, the shaft 22 of which is rotatably supported by a bearing (not shown) fixed to an opposing chassis side plate (not shown). The contact type equal-magnification line image sensor unit 1 is urged onto a conveying roller 21 by a spring 3 whose one end is in contact with a body 29. At this time, the optical axis of the SELFOC lens array l2 of the contact-type equal-magnification line image sensor unit 1 is arranged so as to pass through the center of the rotation axis of the conveyance roller. Further, a gear 32 is fixed to the shaft 22 (see FIG. 2), and transmits driving force from a motor 34. Reference numeral 31 denotes a paper discharge tray, and a peeling plate 27 for peeling the document S from the conveying roller 21 is disposed at the base end of the tray 31. According to the image reading device of this embodiment, a conveyance roller can be provided at the image reading position to face the SELFOC lens array 12, and a white reference surface whose surface is less likely to be stained can be obtained. In other words, it is possible to perform more accurate correction than conventional image reading devices, and
It is much easier to downsize the device than the conventional image reading device shown in Figure 11. Next, the operation of the image reading device of this embodiment will be explained. When a document S is loaded on the document tray 30 and a start key (not shown) is pressed, the motor 35 rotates.
The rotation of is transmitted to the feeding roller 23 via the gear 33,
Furthermore, the rotation of the roller 23 is transmitted to the pickup roller 25 by a belt (not shown). Then, the originals S on the original tray 30 are sent to the feeding roller 23 by the big-up roller 25, and are separated one by one by the feeding roller 23 and the separation pad 6, and only the uppermost original S is sent downstream. Transported. Further, when the leading edge of the document S is detected by the sheet edge sensor 7, the motor 35 rotates for a predetermined time, that is, a time sufficient for the document S to reach the conveying roller 21, and then stops. Furthermore, before the document S is fed to the transport roller 21, the motor 34 is connected to the transport roller 21 via the gear 32.
is rotated in the direction A shown in Figure 343(a), and the transparent substrate 16 is rotated in the direction A due to frictional force. After moving until the end surface of the transparent substrate 16 hits the housing 15, the motor 34 stops. At this time, the white reference plane W provided on the surface of the transparent substrate 16 is the contact type equal-magnification line image sensor unit 1.
It reads the optical information of the white reference surface W and stores it as white reference information (not shown).
to be memorized. As described above, after feeding the original S and reading the white reference surface W, the motor 34 rotates in reverse, and moves the conveying roller 21 via the gear 32 in the direction shown in FIG. The transparent substrate 16 is moved in the direction II by the frictional force until the end of the transparent substrate 16 abuts against the step of the housing 15. At this time, the white reference plane W is avoided from above the reading line. Thereafter, the document S is conveyed while being supported by the conveyance roller 21 and the transparent substrate 16, and the images on the document S that have reached the reading line are sequentially read by the contact type equal-magnification line image sensor unit 1, and the read image information is binarized after correction based on the white reference information stored in the memory. In addition, Hara TR
When the document S is conveyed and the trailing edge of the document S is detected by the sheet edge sensor 7, the motor 34 is operated for a predetermined time, that is, when the trailing edge of the document S is detected by the sheet edge sensor 7.
The paper rotates and stops for a sufficient period of time for the paper to be ejected to the paper ejection tray 31. In this way, y1is is ejected to the paper ejection tray 31 by the document transport roller 21. By repeating the above operations, a plurality of originals S on the original tray 30 are read one after another with a certain interval between each original, and are ejected to the paper ejection tray 31. FIG. 5 is a block circuit diagram showing an example of an i1lt8 circuit for realizing the operation of the image reading apparatus of this embodiment as described above. According to the image reading device of this embodiment as explained above,
It was possible to always perform accurate shading correction, and the device could be made smaller. (Embodiment 2) FIG. 346 is a schematic bottom perspective view showing the structure of a contact type equal-magnification image sensor unit of an image reading device according to a second embodiment of the present invention. Further, FIG. 7 is a schematic cross-sectional view showing the bridge of the drive unit of the image reading device of this embodiment.
The other parts are the same as the m-scanning reading device shown in Figure 'iJ1, Figure 3 <a>, and Figure 13 (b). This embodiment achieves the same effect as the first embodiment with one motor. A gear 41 fixed to the output shaft of a motor (not shown) meshes with gears 42 and 43 (see FIG. 7). gear 4
2 is fitted onto a shaft 22, and is provided with a spring clutch 51 so as to transmit the driving force from the motor in one direction. In addition, in the other direction, the slipping torque of the spring clutch 5l transmits a driving force sufficient to move the transparent substrate 16 by the transport roller 21, and the transparent substrate 1
The end portion of the transport roller 6 abuts against the step of the housing 15, and the torque is set to be lower than the load torque at which the transport roller 21 and the transparent substrate 16 idle. In other words, the transparent substrate l
The spring clutch 5l transmits driving force to the conveying roller 21 until the spring clutch 6 hits the step of the housing 15, and when it hits, the spring clutch 5l idles on the shaft 22 with slipping torque. The gear 43 is fitted onto the shaft 24, and is configured to transmit the driving force from the motor in only one direction by means of a one-way clutch (not shown) built into the gear 43. The rest of the structure is the same as in Example 1.
The one-way clutch at this time is not limited to a spring clutch, and various other clutches can be selected, such as a clutch using cylindrical rollers.Next, the operation of the image reading device of this embodiment will be explained. As in the first embodiment, when the start key is pressed, the motor rotates in the direction D shown in FIG.
from the feed roller 23 through gears 42 and 43, respectively.
It is transmitted to the conveyance roller 21. Similar to Example 1, raw g
The 4S paper feeding operation and the reading operation of the white reference surface W are performed. The difference from Embodiment I is that the gear 43 rotates until the feeding of the original S is completed, that the conveying roller 2l stops when the end surface of the transparent substrate 16 hits the step of the housing 15, and that the gear 42 The spring clutch 5l built into the shaft 22 rotates idly on the shaft 22. After the feeding operation of the document S and the reading operation of the white reference surface W are completed, the motor rotates in the reverse direction, and the motors rotate through the gear 41 and the gears 42 and 42, respectively.
The driving force is transmitted to the shaft 24, but the one-way clutch built in the gear 743 cuts off the drive to the shaft 24, and reading, conveyance, and discharge are performed in the same manner as in the first embodiment. With the image reading device of this embodiment as described above, accurate shading correction can be performed at all times.
Moreover, it was possible to downsize the device. (Embodiment 3) Figure N8 is a schematic cross-sectional view showing a contact type equal-magnification line image sensor of an image reading device according to a third embodiment of the present invention. This embodiment is an embodiment in which the white reference surface W is provided on the side of the transparent substrate 16 that is in contact with the conveyance roller 21, and the conveyance roller 2l is disposed on the upstream side near the reading line.The other configuration is as follows. This is the same as Example 1 or 2. With the image reading device of this embodiment as well, accurate shading correction can be performed at all times, and the device can be miniaturized. (Embodiment 4) FIG. 9 is a schematic cross-sectional view showing a contact type equal-magnification line image sensor of an image reading device according to the N4 embodiment of the present invention. In this embodiment, instead of the transparent substrate 16 in Embodiment 3, a guide substrate 17 made of a stainless steel plate or the like is used, and a white reference plane W is provided on the substrate, and the same line as the reading line of the recording sensor is used. A width slit 18 is provided, and the other configurations are the same as in the third embodiment. With the image reading device of this embodiment as well, accurate shading correction can be performed at all times, and the device can be miniaturized. (Embodiment 5) FIG. 10 is a schematic cross-sectional view showing a contact type equal-magnification line image sensor of an image reading device according to a fifth embodiment of the present invention. In this embodiment, a guide substrate 16 having a white reference surface W is used.
This movement is performed using an electromagnetic clutch 50. With the image reading device of this embodiment as well, accurate shading correction can be performed at all times, and the device can be miniaturized. [Effects of the Invention] As explained above, according to the present invention, it is possible to obtain white reference information that is uniform and stable over time over the entire width of the photoelectric conversion element array, and performs shading based on the white reference information. By performing the correction, it is possible to make appropriate corrections that take into account changes over time in the light source, photoelectric conversion elements, etc., and also has the effect of realizing a low-cost and compact image reading device.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of an image reading device according to the first embodiment, and FIG. 2 is a schematic cross-sectional view showing a contact type 1-magnification image sensor unit that forms the main part of the image reading device shown in FIG. A bottom perspective view, Figure 343(a) is a schematic cross-sectional view of the contact type 1-magnification image sensor unit shown in Figure 2, and Figure 3-
(b) is a schematic cross-sectional view showing the state of the contact type image sensor unit shown in FIG. 3(a) when reading a document, and FIG. 1J5 is a block circuit diagram showing an example of a control circuit for realizing the operation of the image reading device according to the first embodiment, and FIG. 6 is a close-contact type image reading device according to the second embodiment, etc. FIG. 7 is a schematic bottom perspective view showing the configuration of the double image sensor unit, FIG. 7 is a schematic cross-sectional view showing the configuration of the drive section of the image reading device according to the second embodiment, and FIG. 8 is a schematic bottom perspective view showing the configuration of the image reading device according to the third embodiment. FIG. 349 is a schematic cross-sectional view showing a contact type equal-magnification line image sensor, and FIG.
FIG. 0 is a schematic cross-sectional view showing a contact type equal-magnification line image sensor of an image reading device according to Embodiment 5, and FIG. 11 is a schematic cross-sectional view showing an example of a conventional image conversion device. (Explanation of symbols) 1... Close-contact type equal-magnification line image sensor, 3.4...
・Spring, 6... Separation pad, 7... Sheet edge sensor, 11... Photoelectric conversion element array, 12... Self-occuring lens array as a lens system! 3... LED array as a light source, 14.15... Housing, 16... Transparent substrate shaped by glass etc., 2l... Conveyance roller, 22... Shaft of conveyance roller 21, 23・・・
・Feed roller, 24...Axle of feed roller 23, 25・
... Pickup roller, 26 ... Axis, 27 ... Peeling plate, 28.29 ... Machine body, 30.31 ... Document tray, 32.33 ... Gear, 34.35 ... Motor ,41,4 2. 43...gi 7, 6 1, 6 2. 6 3. 64...Conveyance roller, W...White reference surface, S...Document. 9 9J 2 Figure 3 (a) Figure 3 (b) 11 Figure 4 Figure 5 +05 106 +07 +08 Figure 7 Figure 8 Figure 11 Figure 9 Figure 11 Figure 10 Figure 11

Claims (4)

[Claims] (1) Light irradiation means for illuminating the original to be read;
In an image reading device having a photoelectric conversion means for reading an image of the original document and a conveyance means for conveying the original document, a correction reference plane for obtaining correction of an image signal is movably provided. An image reading device characterized by: (2) light irradiation means for illuminating the original to be read;
In an image reading device having a photoelectric conversion means for reading an image of the document and a conveyance means for conveying the document, a correction reference plane for correcting an image signal is defined by the conveyance means. An image reading device characterized in that the image reading device is provided between a conveyance path and the light conversion means. (3) The image reading device according to claim 1 or 2, wherein the correction reference plane is provided on a transparent guide substrate. (4) The image reading device according to claim 1 or 2, wherein the correction reference surface is moved by a driving force transmitted from a conveying means for conveying the original.