JP2001358914A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that corrects a skew of image data by discriminating a skew of an original based on an output of a line sensor reading the image of the original. SOLUTION: When the image reader 1 uses a CCD 13 to receive a reflected light of a light emitted toward an original to read an image of the original, an image processing section 25 conducts original size detection processing to detect a position and a width of the original from an output of the CCD 13, a CPU 20 discriminates a skew denoting the tilt of the original based on the result of detection and the image processing section 25 corrects the tilt of image data of the read original based on the discriminated skew under the control of the CPU 20. Thus, the skew of the original is detected based on the read result of the CCD 13 reading the image of the original to correct the tilt of the image data in response to the skew of the original without the need for provision of a new detection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly, to an image reading apparatus which detects a skew amount of a document and corrects the skew.

[0002]

2. Description of the Related Art In an image reading apparatus, a prescanning process is performed before a reading operation of a document is performed, and a document size detection unit such as a photointerrupter detects a document size set in the reading unit. ing.

However, in the conventional image reading apparatus, only the most common fixed-size original size can be detected, or the original size needs to be accurately detected.

Therefore, the applicant of the present application has firstly described a gamma conversion table memory unit after a shading correction processing unit in an image reading apparatus having a one-dimensional photoelectric conversion element having an image reading function and a document width detecting function. Proposes an image reading apparatus provided with a document size detection processing section in parallel, and a control means for performing document width detection processing by the document size detection processing section without going through the gamma conversion table memory section after performing shading correction. (Japanese Unexamined Patent Publication No.
-130600 publication).

That is, in this image reading apparatus, the position and width of a document are detected by a photoelectric conversion element, an appropriate portion in the document is detected in the sub-scanning direction based on the position and width information of the document, and shading correction is performed. After that, the document size detection processing unit performs document width detection processing without going through the gamma conversion table memory unit, and attempts to detect an accurate document size even for documents other than the standard size.

Conventionally, in an image reading apparatus for reading a document at a high speed, in order to process a large number of documents in a short time, the transport speed of the document is increased or the interval between the transported documents is shortened. As a result, there is a problem in that the skew of the document increases.

Therefore, conventionally, an image sensor for reading an image, an A / D converter for converting the read analog data into digital data, a comparator for comparing the digital data with a predetermined set value, and a main scanning direction Counter, a counter in the sub-scanning direction, and a register for latching the output of each counter, and each time when the image data exceeds a predetermined set value and when the image data falls below a predetermined set value. An image reading apparatus has been proposed which latches counter outputs in the main scanning direction and the sub-scanning direction and calculates the skew amount (see Japanese Patent Application Laid-Open No. 8-317140).

That is, in this conventional image reading apparatus, the skew amount after correction is checked by using the output of the line sensor for image reading, so that the skew amount after correction can be checked without providing a dedicated sensor. In this way, it is possible to check for problems in the skew correction control system, such as a loss of the correction roller and contamination of the sensor.

[0009]

However, in the prior art, it was not possible to properly correct the skew after detecting the skew generated due to the conveyance of the document, and there was a need for improvement. That is, JP-A-8-3
According to the technique described in Japanese Patent No. 17140, the skew amount can be confirmed, but it is not possible to detect the generated skew amount and correct the skew, and perform the image reading operation again. In order to improve the usability of the image reading device, there is a need for improvement.

Accordingly, the invention according to claim 1 is a line sensor in which a plurality of photoelectric conversion elements are arranged one-dimensionally, and when a reflected light of light irradiated toward the original is received to read an image of the original. Performs a document detection process for detecting the position and width of the document from the output of the line sensor, determines the inclination of the document based on the detection result of the document detection process, and determines the document read based on the determined document inclination. By performing a skew correction process for correcting the skew of the image data, the skew of the document is detected based on the reading result of the line sensor that reads the image of the document without providing a new detecting unit, and It is an object of the present invention to provide an inexpensive and easy-to-use image reading device that corrects (skew correction) the inclination of image data according to the inclination of the image data.

According to a second aspect of the present invention, an image of a document is read by a line sensor while the document is being conveyed, and a document detection process and a tilt correction process are performed on the basis of the read image data of the document. An object of the present invention is to provide an image reading apparatus which is inexpensive and has good usability by detecting the inclination of a document generated during conveyance and correcting the inclination of image data according to the inclination of the document.

According to a third aspect of the present invention, an image of a document placed on a predetermined document reading table is read by a line sensor,
By performing a document detection process and a skew correction process based on the image data of the read document, the skew of the document set to be skewed on the document reading table is detected, and the image data of the document is responsive to the skew of the document. It is an object of the present invention to provide an inexpensive and easy-to-use image reading device that corrects the tilt.

[0013]

According to a first aspect of the present invention, there is provided an image reading apparatus comprising: a line sensor in which a plurality of photoelectric conversion elements are arranged one-dimensionally; An image reading device that reads an image of the document, performs document detection processing for detecting the position and width of the document from the output of the line sensor, and determines the inclination of the document based on the detection result of the document detection processing. The above object is achieved by performing a tilt correction process for correcting the tilt of the image data of the read document based on the determined tilt of the document.

According to the above arrangement, the line sensor in which the plurality of photoelectric conversion elements are arranged one-dimensionally receives the reflected light of the light radiated toward the document and reads the image of the document when the image of the document is read. Performs document detection processing for detecting the position and width of the document, determines the inclination of the document based on the detection result of the document detection processing, and determines the inclination of the image data of the document read based on the determined inclination of the document. Since the skew correction process for correcting the skew is performed, the skew of the document is detected based on the reading result of the line sensor that reads the image of the document without providing a new detecting unit, and the skew of the document is detected. Accordingly, the inclination of the image data can be corrected (skew correction), and the image reading apparatus can be inexpensive and have good usability.

In this case, for example, the image reading apparatus reads the image of the document by the line sensor while transporting the document, and based on the image data of the read document. The document detection process and the tilt correction process may be performed.

According to the above arrangement, the image of the original is read by the line sensor while the original is being transported, and the original detection processing and the inclination correction processing are performed based on the read image data of the original. , The inclination of the image data can be corrected in accordance with the inclination of the original, and the image reading apparatus can be made inexpensive and have good usability.

Further, for example, the image reading device reads the image of the document placed on a predetermined document reading plate with the line sensor, and reads the image of the read document. The document detection process and the tilt correction process may be performed based on data.

According to the above arrangement, the image of the document placed on the predetermined document reading table is read by the line sensor, and the document detection processing and the inclination correction processing are performed based on the read image data of the document. Therefore, it is possible to detect the inclination of the original set at an inclination on the original reading table and to correct the inclination of the image data according to the inclination of the original. It can be.

[0019]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 14 show an embodiment of the image reading apparatus of the present invention. FIG. 1 shows an image reading apparatus 1 to which the embodiment of the image reading apparatus of the present invention is applied. It is a block block diagram.

In FIG. 1, an image reading apparatus 1 has a document reading table 3 provided on an upper part of a main body 2, and the document reading table 3 is usually provided with a contact glass. An openable document pressing plate 4 is provided on the upper portion of the document reading table 3, and the document pressing plate 4 is configured to bring the document G set on the document reading table 3 into close contact with the contact glass of the document reading table 3. Press down on.

An automatic paper feeder (ADF) 5 is provided on the upper right side of the main body 2 of FIG.
Includes an ADF unit 6 and a document table 7. AD
A stepping motor 8 is provided in the F unit 6, and a plurality of documents G are stacked on the document table 7. The automatic paper feeder 5 separates a plurality of originals G placed on the original table 7 one by one by the ADF unit 6 and rotates the rollers 17 to 19 (FIG. 3) driven by the stepping motor 8. ), And is conveyed to a discharge tray (not shown) through the document reading table 3.

A white reference plate 9 for shading correction is provided at an end of the document reading table 3 on the ADF unit 6 side. Further, the automatic paper feeder 5 has an integral structure with the original presser plate 4, and when the original presser plate 4 is opened, the automatic paper feeder 5 is also opened and closed together.

Inside the main body housing 2, a first traveling body 10,
Second traveling body 11, lens 12, CCD (Charge Coupled)
Device) 13 and an exposure scanning optical system 15 including a stepping motor 14 and the like are provided.
The light source 10a and the mirror 10b, and the second traveling body 1
1 has mirrors 11a and 11b, respectively.

The exposure scanning optical system 15 is configured such that the first traveling body 10 and the second traveling body are moved in the horizontal direction (sub-scanning direction) by the stepping motor 14 and the light source 1 on the first traveling body 10 is moved.
0a, for example, irradiating a document G placed on the document reading table 3 with light from a fluorescent lamp or the like, and reflecting the light reflected by the document on the second mirror 10b on the first traveling body 10 Running body 1
The light that is reflected in one direction and is incident from the first traveling body 10 on the mirrors 11a and 11b on the second traveling body 11 is sequentially reflected and emitted toward the lens 12. Lens 12
Collects and irradiates the light incident from the second traveling body 11 onto the CCD 13. The CCD (line sensor) 13 includes 1
CCD elements are arranged as a plurality of photoelectric conversion elements in a dimension, and photoelectrically convert incident light incident from the lens 12 to output analog image data (image signal). The exposure / scanning optical system 15 irradiates the white reference plate 9 with light, and reflects the reflected light from the white reference plate 9 in the same manner as described above.
3 and is output from the CCD 13 as white reference data.

As shown in FIG. 2, the image reading apparatus 1 has a book reading mode in which the document pressing plate 4 is opened and the image of the document G placed on the document reading table 3 is read. As shown in FIG. 3, the plurality of rollers 17 to 19 are driven to rotate by the stepping motor 8 of the ADF unit 6 using the automatic paper feeder 2 so that the plurality of originals G placed on the There is an ADF mode in which the image of the document G is transported one by one onto the document reading table 3 to read the image of the document G.

In the book mode, as shown in FIG. 2, when the document presser plate 4 is opened and the document G is set on the document reading table 3 in the book mode, the light source 10a is turned on, and , The white reference plate 9 is read to obtain reference data for shading correction, and then the stepping motor 14 is driven to move the first traveling body 10 and the second traveling body 11 from the original G to the CCD 13. The document is moved in the sub-scanning direction while the optical path length is constant, and the image of the document G on the document reading table 3 is read.

In the ADF mode, as shown in FIG. 3, the image reading device 1
Is set, the light source 10a is first turned on to read the white reference plate 9, and then the stepping motor 8
Is driven to separate the documents G set on the document table 7 one by one by a separation roller 17, and transported by transport rollers 18 and 19, and transported to a predetermined reading position of the first traveling body 10. . At this time, the original G is transported at a constant speed,
While the first traveling body 10 and the second traveling body 11 are stopped,
The light source 10a on the first traveling body 10 irradiates the conveyed document G with light, and the light from the document G reflected by the document G is reflected on the mirror 10b and the mirror 11 on the second traveling body 11.
a, 11b, and reflected by the CCD 13 through the lens 12.
, And photoelectrically converted by the CCD 13 to read the image of the original G.

The image reading apparatus 1 has a circuit block configuration as shown in FIG. 4, and has a CPU (Central Procedures).
sing unit) 20, ROM (Read Only Memory) 21,
RAM (Random Access Memory) 22, Light source driver 2
3, light source 10a, CCD driving unit 24, CCD (photoelectric conversion element) 13, image processing unit 25, buffer controller 2
6, I / F controller 27, line buffer 28, page memory 29, scan buffer 30, motor driver 31, stepping motor 14, motor driver 32
And a stepping motor 8.

The ROM 21 stores various programs such as a basic processing program as the image reading device 1, a document detection / skew correction processing program described later, and various data necessary for executing these various programs. The RAM 22 stores various data necessary for the operation of the image reading device 1. The CPU 20 controls each unit of the image reading apparatus 1 to execute a sequence as the image reading apparatus 1 while using the RAM 22 as a work memory based on a program in the ROM 21, and also detects a document detection and skew correction described later. Perform processing.

The light source 10a is controlled to be turned on and off by a light source driver 23 under the control of the CPU 20.
D <b> 13 is driven by the CCD drive unit 24 and outputs the photoelectrically converted image data to the image processing unit 25.

The stepping motor 8 is driven by a motor driver 32, and the stepping motor 14
Driven by the motor driver 31.

The image processing unit 25 includes a line buffer 28
And the page memory 29 are connected, and the image processing unit 2
5 is an analog video processing unit 41, as shown in FIG.
Shading correction processing unit 42, image data processing unit 4
3, a timing generator 44, an image data output unit 45, and the like.

The analog video processing section 41 includes a CCD 1
The analog image signal output from the input unit 3 is input, and the analog image signal is converted into a digital signal and output to the shading correction processing unit 42 as digital image data.

The shading correction processing section 42 stores image data obtained when the white reference plate 9 is read as reference data in the internal RAM, and performs shading correction on the image data obtained when the document G is read based on the reference data. Then, the image data after the shading correction is output to the image data processing unit 43.

The image data processing unit 43 performs various types of image processing on the image data subjected to the shading correction by the shading correction processing unit 42 based on the enable signal EN input from the timing generation unit 44, and outputs the image data to the image data output unit. The image data output unit 45 converts the processed image data into binary data or multi-valued data and outputs the converted data to the buffer controller 26. The image data processing unit 43 stores, for example, image data for several lines in the line buffer 28, forms a matrix, and performs a spatial filtering process or the like on the image data. The timing generator 44 outputs a stepping pulse SP to the motor driver 31 and the motor driver 32 to control the drive timing of the stepping motor 14 and the stepping motor 8 via the motor driver 31 and the motor driver 32.

The image data subjected to the image processing and the document size detection processing in the image processing section 25 is stored in the scan buffer 30 via the buffer controller 26,
The information is output to another information processing device (not shown), such as a personal computer, via the / F controller 27.

The image data processing unit 43 performs a document size detection process based on the image data input from the shading correction processing unit 42, and outputs a detection result to the CPU 20 as detection data. That is, the image data processing unit 43 is a circuit of the original size detection system as shown in FIG.
As shown in FIG. 7, the image processing apparatus includes a gamma conversion table 51, a document size detection processing section 52, a scaling processing section 53, and the like. And input to the document size detection processing unit 52.

The gamma conversion table 51 performs a table conversion process on input shading-corrected image data based on predetermined table data, and temporarily stores the converted image data in the page memory 29. Thus, the data is output from the page memory 29 to the scaling unit 53 as data after gamma conversion.

The document size detection processing section 52 binarizes the input shading-corrected image data, generates detection data for detecting the document width and the document position, and outputs the detection data to the CPU 20. The magnification change processing section 53
Based on the document size information input from the PU 20, the image data after the gamma conversion is scaled to a size corresponding to the document size information and sent to the next stage of processing.

As described above, the image reading apparatus 1 has the automatic paper feeder 5 and the document pressing plate 4 integrated with each other, and the ADF unit 6 moves the document G on the document table 7 in the direction of the document reading table 3. When the document is conveyed to the ADF mode, the document passes through the reading position in the ADF mode and reads the image of the original G at the reading position. The ADF unit 6 at this reading position, as shown in FIG. The reading position member 60 located on the back side of the document G is provided with a predetermined density at a uniform density, and the reading position member 60 is provided with a light source 10a as shown in FIG. When the original G is irradiated on the original G passing through the reading position of the reading position member 60 and the reflected light is photoelectrically converted by the CCD 13, the background density of the original G and the density of the reading position member 60 become clear. It is a color that can be cut and is dark It has been subjected to. For example, the density level of a general white original is O.D. Since the D value (optical density value) is about 0.1, the reading position member 60
Are uniformly colored in a color that can be appropriately separated from the white document. In FIG. 7, the document size detection position A indicates a document size detection line for detecting the document size.

The reading position member 60 has a constant density level as shown in FIG. 8 along with the line synchronization signal. In the present embodiment, for the sake of simplicity, the description will be made with the black level being a high density level and the white level being a low level. In FIG. 8, position B indicates a reading start position in the main scanning direction, and position C indicates a reading end position in the main scanning direction. In FIG. 8, the end of the reading position member 60 in the main scanning direction also corresponds to the B position and the C position, but the width of the reading position member 60 in the main scanning direction is wider. Is also good.

The document size detection processing section 52 binarizes the image data of the document G conveyed to the document size detection position A on the reading position member 60 and converts the image data into CP data as detection data.
U20, and the CPU 20 detects the document G based on the detection data, and detects the width and position of the document G.

That is, although not shown, the CPU 20
A pixel counter and a line counter are provided for each of the main scanning direction and the sub-scanning direction, and the position (original position) and width (original width) of the original G are determined using the pixel counter and the line counter in the main scanning direction. The length of the document G is detected using a pixel counter and a line counter in the sub-scanning direction. The CPU 20 sequentially counts up the pixel data at the position B in FIG. 8 as the first pixel of the pixel counter in the main scanning direction.

FIG. 9 shows the density level distribution of the image data when the original G is detected, and shows that the density level between the D position and the E position is small on the white background of the original G. I have. Therefore, the original G is determined by the count value of the pixel counter in the main scanning direction from the position D to the position E in FIG.
Are digitized, and the position and width of the document G can be detected from the point position indicated by the digitized address.

When the CPU 20 detects the width of the document G in the main scanning direction, the CPU 20 reads the document G and performs a detection process of the length in the sub-scanning direction at the same time as reading the document G. Based on the acquired document width information, the width position where the document G passes is determined and set. CPU 20
Determines one of the left and right ends of the set document passing position as a document sub-scanning detection point, detects the density level at the position, detects the start line and the end line of the document G, The length of the document G in the sub-scanning direction is detected. For example, as shown in FIG. 10 with the density level together with the line synchronization signal, the section from the position D to the position E in FIG. 10 is a predetermined document passage area, and the size of this document passage area as a size detection position in the sub-scanning direction is One of the points indicated by T in FIG. 10 is determined as the document sub-scanning detection point, the density level at that position is detected, and the start line and the end line of the document G are detected.
The length of the document G in the sub-scanning direction is detected.

At this time, the original G to be subjected to the detection processing is
As shown by a broken line in FIG. 1, in the non-recording area 16b, which is an area having a specified width inside the end of the document G, appropriate detection cannot be performed if the document density is different. Is excluded, and an image is formed only in the image area 16a inside the boundary line.

In the above-described document size detection processing, the CPU 20 skews (or tilts) the document G as described later.
It is determined whether or not skew has occurred. If skew has occurred, the skew amount is detected, and skew correction is performed according to the detected skew amount.

Next, the operation of the present embodiment will be described. The image reading apparatus 1 according to the present embodiment performs document size detection, determines the presence or absence of skew based on the detection result, and determines the amount of skew that has occurred when skew occurs, and determines the image based on the determination result. Data is deskewed.

The image reading apparatus 1 uses the automatic paper feeder 5 to convey the original G in the direction of the original reading table 3 to read the image, and also to read the original G placed on the original reading table 3. When reading an image, the size of the document G and the presence or absence of skew are determined. If skew has occurred, the skew amount is detected and skew correction is performed.

That is, the image reading apparatus 1 has a book mode and an ADF mode as document reading modes.
Since there is a high possibility that skew occurs when reading the document G in the ADF mode, the process of detecting the presence or absence of skew and the process of correcting the skew in the ADF mode are described below.
explain.

In the ADF mode, the image reading apparatus 1 starts the skew detection process before the document G is conveyed to the document size detection position A, and detects the document G at the document size detection position A. The document size detection processing unit 52 of the image data processing unit 43 generates an interruption to the CPU 20 at each predetermined timing, and outputs detection data indicating position information and width information of the document G.

The CPU 20 includes a document size detection processing section 52
Writes the document position information and document width information of the detection data transferred from the internal register to the internal register, retrieves the document position information and document width information from the last time the interrupt occurred from the internal register, and transfers it when the current interrupt occurs The obtained document position information is compared with the document width information.

Now, assuming that the document G is being transported with the left side in the transport direction ahead of the right side and skewed to the left as shown in FIG. 12, as shown in FIG.
In the state (a), since the leading end of the document G has not been conveyed to the document size detection position A, which is a detectable area,
The read image data is image data obtained by reading only the reading position member 60, and has uniform density distribution.
No interrupt is generated for 20.

Further, when the original G is conveyed and the leading end of the original G appears at the reading position for the first time, the left leading end of the skewed original G appears in the line data of the reading line at the original size detection position A. Then, as shown in FIG. 12B, the left end of the original G is detected,
The document size detection processing section 52 causes the CPU 20 to generate an interrupt for the first time. When an interrupt occurs and the detection data is transferred, the CPU 20 writes document position information and document width information indicated by the detection data into an internal register.

The document size detection processing section 52 is configured as shown in FIG.
As shown in (c), when the line data of the next read line is input, similarly, an interrupt is generated in the CPU 20, and the document position information and the document width information based on the line data are transferred to the CPU 20, The CPU 20 stores the document position information and the document width information transferred by the current interrupt in an internal register, and compares the document position information and the document width information at the time of the previous interrupt with the current document position information and the document width information. I do. As is clear from the comparison between FIG. 12B and FIG. 12C, since the document width is wide,
U20 determines that the document G is skewed and that the document width has not reached the maximum width at this time and is still expanding.

Further, when reading of the next reading line is performed and line data is input, the document size detection processing section 52 causes the CPU 20 to generate an interrupt as described above, and The position information and the document width information are transferred to the CPU 20. The CPU 20 stores the document position information and the document width information transferred by the current interruption in an internal register, and also stores the document position information and the document width information at the time of the previous interruption. Is compared with the current document position information and document width information. As is apparent from a comparison between FIG. 12C and FIG. 12D, since the document width is wide, C
The PU 20 indicates that the original G is skewed, and
It is determined that the document width has not reached the maximum width at this time and is still expanding.

Then, when the next reading line is read and line data is input, the document size detection processing section 52 causes the CPU 20 to generate an interrupt in the same manner as described above, based on the line data. The document position information and the document width information are transferred to the CPU 20. The CPU 20 stores the document position information and the document width information transferred by the current interruption in the internal register, and also stores the document position information and the document width at the previous interruption. The information is compared with the current document position information and document width information. As is apparent from a comparison between FIG. 12D and FIG. 12E, there is no change in the document width.
The CPU 20 determines that the document G is skewed and has been conveyed to the maximum width of the document G. In addition,
The detection data in FIG. 12E is used to confirm whether the document width information in the detection data in FIG. 12D is the maximum width.

The transport distance of the original G in FIGS. 12B to 12D is the amount of displacement of the original G due to skew, and the CPU 20 detects the leading end of the original G in FIG.
The position information (x1, y2) in FIG. 12B and the position information (x2, y3) − (x3,
Using y3), the skew amount is calculated by the following equation.

Skew amount = (y3−y2) / (x1−x2) (1) Even when such a skew occurs, the image reading apparatus 1 performs the reading operation of the original G. Subsequently, the read image data is gamma-converted by the gamma conversion table 51 as described above, and then stored in the page memory 29. The skew correction is performed on the image data stored in the page memory 29. Do.

That is, as shown in FIG. 12, the image data of the skewed original G obtained by performing the skew detection as shown in FIG. After that, it is stored in the page memory 29. That is, in FIG. 14, when the leading end of the document G is read, the image data corresponding to FIG. 13B is stored in the memory address of A020 to A02FH, and the image data of the next line is stored in the memory of A030 to A030FH. At the address, and in turn, the next line of image data
A040 to A040FH memory address, A050 to A040
A050FH memory address, A060-A060F
H are sequentially stored in the memory address.

As described above, the image data stored in the page memory 29 is read, and the processing at the next stage, that is,
The skew correction process is performed when outputting to the scaling unit 53. That is, when calculating the skew amount by performing the arithmetic processing based on the above equation (1), the CPU 20 specifies the original image data of the first line. The original first-line image data, that is, the original first-line image data of the read image data in the original document G leading edge detection processing and the maximum width detection processing, detects the leading edge address (x1, y1) and the maximum width. End address [(x2, y3)-(x3, y
3)] exists on the line connecting either of the above. For example, in the present embodiment, the line connecting the address (x1, y1) and the address (x2, y3) is the original first line of image data. The starting point of the image data is (x1, y1)
The image data of the first line exists from here to (x2, y3). The image data is stored in the page memory 29 from the memory address of A024H.
It exists on the memory address connecting the memory addresses of 05EH.

Since the skew amount is given by the above equation (1), as described above, the image data of the memory address corresponding to the skew amount is sequentially read from the starting memory address and output as one line data. By doing so, the skew-corrected image data is output to the next-stage scaling unit 53.

Thereafter, in accordance with the detected skew amount, image data of the second line, image data of the third line,.
By reading out the image data of the last line, it is possible to read out and output the image data of one document G in a skew-corrected state.

In the above description, the case where the start point of the image data of the original G is the leading end of the original G has been described. However, the end address of the line where the maximum width of the original is detected may be the start point. In this case, similarly, from the memory address where the image data of the end address is stored to the memory address where the image data of the start address is sequentially stored, the memory address is controlled in accordance with the skew amount to transfer the image data. It can be processed by reading.

In the above description, the skew correction is performed by temporarily storing the image data of one document G in the page memory 29 and then controlling the read address when outputting the image data to the next stage. The skew correction method is not limited to the above method.

Furthermore, in the above description, the case where the skew generated when the original G is conveyed in the ADF mode is detected and the skew is corrected has been described, but the original G is placed obliquely on the original reading table 3 in the book mode. Even in the case where the skew is set, the skew can be detected and the skew can be corrected in the same manner.

As described above, in the image reading apparatus 1 of the present embodiment, when the CCD 13 receives the reflected light of the light radiated toward the original G and reads the image of the original G,
A document detection process (document size detection process) for detecting the position and width of the document G from the output of the CD 13 is performed, and the skew, which is the inclination of the document G, is determined based on the detection result of the document detection process. A skew correction process is performed to correct the inclination of the image data of the document G read based on the skew.

Therefore, the skew of the original G is detected based on the reading result of the CCD 13 for reading the image of the original G without providing a new detecting means, and the original G is detected.
The inclination of the image data can be corrected in accordance with the skew, and the image reading apparatus 1 can be inexpensive and have good usability.

Further, the image reading device 1 of the present embodiment
The image of the original G is read by the CCD 13 while the original G is being conveyed, and original detection processing and skew correction processing are performed based on the read image data of the original G.

Therefore, the skew of the original G generated when the original G is conveyed can be detected, and the inclination of the image data can be corrected in accordance with the skew of the original G. It can be good.

Further, the image reading apparatus 1 of the present embodiment
Is an image of the original G placed on the original reading table 3
In step S13, a document detection process and a skew correction process are performed based on the read image data of the document G.

Therefore, it is possible to detect the inclination of the original G set to be inclined on the original reading table 3 and correct the inclination of the image data in accordance with the inclination of the original G. And good usability.

As described above, the invention made by the inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

[0075]

According to the image reading apparatus of the first aspect of the present invention, a line sensor in which a plurality of photoelectric conversion elements are arranged one-dimensionally receives reflected light of light irradiated toward the original, and When reading the image of the original, perform a document detection process of detecting the position and width of the document from the output of the line sensor,
Since the inclination of the original is determined based on the detection result of the original detection processing, and the inclination of the image data of the read original is corrected based on the determined inclination of the original, the inclination correction processing is performed. Without providing any means, it is possible to detect the inclination (skew) of the original based on the reading result of the line sensor that reads the image of the original and correct the inclination (skew correction) of the image data according to the inclination of the original. Thus, the image reading apparatus can be made inexpensive and have good usability.

According to the image reading apparatus of the present invention, the image of the original is read by the line sensor while the original is being conveyed, and the original detecting process and the inclination correcting process are performed based on the read image data of the original. Since it has been performed, it is possible to detect the inclination of the original that occurs when the original is transported, and correct the inclination of the image data according to the inclination of the original.
The image reading device can be inexpensive and have good usability.

According to the image reading apparatus of the present invention, an image of a document placed on a predetermined document reading table is read by a line sensor, and a document detection process is performed based on the read image data of the document. And the skew correction process, the skew of the document set at an angle on the document reading table can be detected, and the skew of the image data can be corrected in accordance with the skew of the document. It can be inexpensive and have good usability.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a main part of an image reading apparatus to which an embodiment of the image reading apparatus of the present invention is applied.

FIG. 2 is a schematic front view of a main part of the image reading apparatus in FIG. 1 during a reading operation in a book mode.

FIG. 3 is a schematic front view of a main part of the image reading apparatus in FIG. 1 during a reading operation in an ADF mode.

FIG. 4 is a block diagram of a main part circuit of the image reading apparatus of FIG. 1;

FIG. 5 is a detailed circuit block diagram of the image processing unit in FIG. 4;

FIG. 6 is a detailed circuit block configuration diagram of a document size detection system of the image data processing unit in FIG. 5;

FIG. 7 is a plan view of a reading position member and a document arranged at a reading position of the document in the ADF mode.

FIG. 8 is a diagram showing a density level when a reading position member of FIG. 7 is read together with a line synchronization signal.

FIG. 9 is a diagram illustrating a density level when the document illustrated in FIG. 7 is read together with a line synchronization signal.

FIG. 10 is a diagram illustrating a density level of a reading position member and a line synchronization signal when detecting the length of a document in the sub-scanning direction.

FIG. 11 is a plan view showing an image area and a non-image area of a document.

FIG. 12 is a plan view showing a state where a document is being conveyed in a state of being skewed on a reading position member.

FIG. 13 is a diagram illustrating a density level of line data at each conveyance point when the skewed document illustrated in FIG. 12 is read together with a line synchronization signal.

FIG. 14 is a diagram showing image data in a page memory obtained by reading the skewed document shown in FIG. 12;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image reading device 2 main body housing 3 document reading table 4 document pressing plate 5 automatic paper feeder (ADF) 6 ADF unit 7 document table 8 stepping motor 9 white reference plate 10 first traveling body 10a light source 10b mirror 11 second traveling Body 11a, 11b Mirror 12 Lens 13 CCD 14 Stepping motor 15 Exposure scanning optical system 16 Document 17 Separation roller 18, 19 Transport roller 20 CPU 21 ROM 22 RAM 23 Light source driver 24 CCD drive unit 25 Image processing unit 26 Buffer controller 27 I / F controller 28 line buffer 29 page memory 30 scan buffer 31, 32 motor driver 41 analog video processing unit 42 shading correction processing unit 43 image data processing unit 44 timing generation unit 45 image data output unit 51 Gamma conversion table 52 Document size detection processing unit 53 Magnification processing unit 60 Reading position member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/40 H04N 1/40 101Z

Claims (3)

[Claims] 1. An image reading apparatus, comprising: a line sensor in which a plurality of photoelectric conversion elements are arranged in a one-dimensional array, receiving reflected light of light emitted toward a document and reading an image of the document. Performs document detection processing for detecting the position and width of the document from the output of the document, determines the inclination of the document based on the detection result of the document detection processing, and reads the document based on the determined document inclination. An image reading apparatus for performing a tilt correction process for correcting a tilt of the image data. 2. The image reading device according to claim 1, wherein the image of the document is read by the line sensor while the document is being conveyed, and the document detection process and the tilt correction process are performed based on the read image data of the document. The image reading device according to claim 1, wherein: 3. The image reading device reads an image of the document placed on a predetermined document reading table with the line sensor, and performs the document detection process and the tilt based on image data of the read document. 2. The image reading device according to claim 1, wherein a correction process is performed.