JP7423246B2 - Original reading device - Google Patents

Description

The present invention relates to an image reading device that reads an image (original image) from a document being transported.

A multifunction device or a copying machine is configured by combining an image reading device that reads a document image with a reading sensor and generates image data representing the document image, and an image forming device that prints an image on a sheet based on the image data. Ru. The image reading device uses an automatic document feeder (hereinafter referred to as "ADF: Auto Document Feeder") when reading document images while continuously conveying a plurality of documents. The ADF transports the document using transport rollers. The conveyance rollers may convey the document in a skewed manner due to factors such as wear. When the document is skewed, the reading sensor reads the document image while the document is tilted with respect to the transport direction. In this case, the read original image is also tilted. For this purpose, tilt correction processing is generally performed to correct the tilt of image data.

When correcting the tilt of image data, the maximum correction angle is generally determined by the capacity of memory that can be used for processing. In Patent Document 1, when a document image is tilted by more than the maximum correction angle, the user selects whether to perform the tilt correction or to perform the correction up to the maximum correction angle.

Japanese Patent Application Publication No. 2000-244728

The ADF includes a lead roller and a scanning glass at the reading position of the reading sensor. If there is dust or scratches on the read roller or the scanning glass, the image of the dust or scratches may be included in the image data when reading the original image. Tilt correction of image data is performed by detecting the edge of the document, and detecting the amount of tilt from the edge and the center of rotation when rotating the image data. Scratches and dust included in image data may be erroneously detected as edges of a document. If scratches or dust included in the image data are erroneously detected at the edges of the document, the amount of tilt may not be a normal value, and accurate tilt correction of the image data may not be performed. Even the technique disclosed in Patent Document 1 cannot cope with erroneous detection of the edge of the document when the skew of the document is within the maximum correction angle.

The present invention has been made in view of the above problems, and it is an object of the present invention to suppress output of results resulting from inappropriate tilt correction.

The document reading device of the present invention includes a document tray on which a document is placed, a document guide that regulates the widthwise position of the document placed on the document tray, and a document guide that regulates the widthwise position of the document placed on the document tray. a conveying means for conveying the document, a reading means for reading the document being conveyed by the conveying means, and a tilt based on the leading and trailing ends of the document in the conveying direction based on the reading result of the document by the reading means. a tilt detection means for detecting an intersection point between a leading edge in the conveying direction and a lateral edge in the width direction of the document as a rotation center position for correcting the tilt of the document; a correction means for correcting the inclination of the read result by rotating the read result by the inclination amount based on a reference; It is determined whether or not the reading result is in a normal range where correction is possible, and if the reading result is within the normal range, the reading result with the tilt correction is output, and if it is not in the normal range, the reading result without the tilt correction is output. A control means for outputting a reading result.

According to the present invention, it is possible to suppress output as a result of inappropriate tilt correction.

FIG. 2 is a configuration diagram of an image reading device. An explanatory diagram of a controller. An explanatory diagram of a method for detecting document width. FIG. 3 is a diagram illustrating a state in which a document is skewed. (a) and (b) are explanatory diagrams of the detection results of the lateral edge of the document. A flowchart showing image reading processing. Another flowchart showing image reading processing. An illustrative diagram of a cleaning screen.

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

(Configuration of image reading device)
FIG. 1 is a configuration diagram of an image reading device according to this embodiment. The image reading device 1000 includes an image reading section 200 that reads an original image, and an automatic document feeder (ADF 100) that transports the original to a reading position of the image reading section 200. The image reading apparatus 1000 is provided on an image forming apparatus, for example, when used in a copying machine or a multifunctional device.

The image reading unit 200 includes an optical scanner unit 202 in a housing, and includes a document table glass 209, a panning glass 201, and a white reference plate 210 on the ADF 100 side of the housing. When reading a document image from a document placed on document table glass 209, optical scanner unit 202 reads the document image line by line while moving at a constant speed in the sub-scanning direction indicated by the arrow in FIG. The process of reading a document image from a document placed on document table glass 209 is called "fixed reading." When reading a document image from a document using the ADF 100, the optical scanner unit 202 reads the document image line by line at the timing when the document conveyed by the ADF 100 passes a reading position. In this case, optical scanner unit 202 does not move. The process of reading a document image from a document using the ADF 100 is called "skimming". The white reference plate 210 is read by the optical scanner unit 202 before performing fixed reading and continuous reading. The optical scanner unit 202 is calibrated using the reading result of the white reference plate 210 as a white reference.

The ADF 100 includes a document tray 30 on which a document bundle S consisting of one or more sheet-like documents is loaded, a paper feed roller 1, and a document tray 30 in which the document bundle S is placed downstream in the conveyance direction from the document tray 30 before the document begins to be conveyed. It is provided with a separation pad 21 and a separation roller 2 that restrict protrusion to the side. The document tray 30 of this embodiment can load up to 100 sheets of plain paper. The document tray 30 is provided with a document presence detection sensor 14 . The document presence/absence detection sensor 14 detects the presence or absence of a document on the document tray 30 . The paper feed roller 1 falls onto the uppermost document surface of the document bundle S stacked on the document tray 30 and rotates. As a result, the uppermost original in the bundle of originals is fed. A document fed by a paper feed roller 1 is separated into one sheet by a separation roller 2 and a separation pad 21, and is conveyed along a conveyance path. Separation of documents is achieved by a known separation technique.

The conveyance path is provided with a pull-out roller 3, a registration roller 4, a reading upstream roller 5, a lead roller 6, a reading downstream roller 7, and a paper discharge roller 12. The document separated by the separation roller 2 and separation pad 21 is conveyed along a conveyance path to an image reading position by a pull-out roller 3, a registration roller 4, and a reading upstream roller 5. At this time, the registration rollers 4 correct the skew of the document. Correction of skew by the registration rollers 4 is performed as follows.
When the document is conveyed by the pull-out roller 3, the registration roller 4 stops rotating. For this purpose, the document conveyed to the registration rollers 4 by the pull-out roller 3 has its leading end abutted against the registration roller 4 by the pull-out roller 3 . Even after the leading edge of the document abuts against the registration rollers 4, the pull-out rollers 3 transport the document a predetermined distance. As a result, the document forms a loop-like flexure, and skew during conveyance is eliminated.

At the reading position, a scanning glass 201 and a lead roller 6 are provided with a conveyance path in between. When the original passes between the scanning glass 201 and the read roller 6, the image of the original is read by the optical scanner unit 202.

The document that has passed the reading position is conveyed to the paper ejection roller 12 by the reading downstream roller 7 . A reversing path 19 for returning the document to the registration rollers 4 is provided on the conveyance path between the reading downstream roller 7 and the paper ejection roller 12. When reading only the original image on the front surface (first side) of the original, the paper ejection roller 12 ejects the original after passing the reading position to the paper ejection tray 13 . When reading images on both sides of a document, the document is conveyed to the reversing path 19 . The document is conveyed to the registration rollers 4 with its front and back sides reversed by passing through the reversing path 19 . The document conveyed to the registration rollers 4 can be read at a reading position so that the document image on the back side (second side) can be read. The original is reversed as follows.
Conveyance of the document is stopped before the trailing edge passes through the paper ejection roller 12. Then, the document is conveyed to the reversing path 19 side by rotating the paper discharge roller 12 in the reverse direction. The document is conveyed to the registration rollers 4 via the reversing path 19, and the document image on the second side is read in the same way as on the first side. Further, the document from which the document image on the second side has been read is conveyed to the registration rollers 4 via the reversing path 19 again. Since the original images on both sides have been read, the original passes through the reading position and is ejected to the paper ejection tray 13 without the original images being read.

A post-separation sensor 15, a registration sensor 17, a lead sensor 18, and a discharge sensor 11 are provided on the conveyance path in this order from the upstream side of the conveyance path. Post-separation sensor 15 detects the document fed by paper feed roller 1 and separation roller 2 . The registration sensor 17 is provided upstream of the registration rollers 4 in the conveyance direction, and detects the document being conveyed. Driving of the registration rollers 4 is controlled according to the detection result of the registration sensor 17. The read sensor 18 is provided upstream of the reading upstream roller 5 in the conveying direction, and detects the document being conveyed. According to the detection result of the read sensor 18, the driving of the reading upstream roller 5 and the lead roller 6 is controlled, and the reading operation of the optical scanner unit 202 is controlled. The paper ejection sensor 11 is provided upstream of the paper ejection roller 12 in the conveyance direction, and detects the document being conveyed. The drive of the paper ejection roller 12 is controlled according to the detection result of the paper ejection sensor 11.

The optical scanner unit 202 of the image reading section 200 reads a document image with the depth direction in FIG. 1 (direction orthogonal to the conveyance direction of the document) as the main scanning direction during continuous reading and fixed reading. The optical scanner unit 202 includes LEDs (Light Emitting Diodes) 203a and 203b serving as light sources (light emitting units), a plurality of mirrors 204a to 204c, and an image reading sensor 208 serving as a light receiving unit. The LEDs 203a and 203b illuminate the surface of the document on which the image will be formed. The reflected light of the light irradiated onto the original is guided to the image reading sensor 208 by mirrors 204a to 204c. The image reading sensor 208 receives reflected light, converts the reflected light into an electrical signal, and outputs image data. This image data represents an image including a document image formed on the document and an image around the document. The image around the document is, for example, an image of the scanning glass 201 and the lead roller 6 provided at the reading position.

(controller)
FIG. 2 is an explanatory diagram of a controller that controls the operation of the image reading apparatus 1000. The controller includes a first controller 310 and a second controller 300. The first controller 310 and the second controller 300 are connected by a communication line 354 and an image line 353 so that they can communicate with each other. The first controller 310 is provided in the image reading device 1000. The second controller 300 is provided in the image forming apparatus, for example, when the image reading apparatus 1000 constitutes a copying machine or a multifunction peripheral.

The first controller 310 includes a CPU (Central Processing Unit) 801, a ROM (Read Only Memory) 802, and a RAM (Random Access Memory) 803. The CPU 801 controls the operation of the image reading apparatus 1000 by executing a computer program stored in the ROM 802 according to instructions from the second controller 300 . At this time, RAM 803 provides a work area. The first controller 310 further includes a tilt detection section 830 and an image processing section 833. The tilt detection unit 830 detects the tilt of the original (original image) during transport of the original based on the image data. The image processing unit 833 performs image processing including tilt correction processing for correcting image data according to the amount of tilt detected by the tilt detection unit 830. Details of the tilt detection section 830 and the image processing section 833 will be described later. The CPU 801, ROM 802, RAM 803, tilt detection section 830, and image processing section 833 are communicably connected via bus B1.

The bus B1 also includes a separation motor 820, a reading motor 821, a post-separation sensor 15, a document guide width detection sensor 10, a document presence/absence detection sensor 14, a registration sensor 17, a read sensor 18, a paper ejection sensor 11, and an optical scanner unit 202. Connected. The separation motor 820 rotationally drives the paper feed roller 1 , the separation roller 2 , the pull-out roller 3 , and the registration roller 4 . The reading motor 821 rotationally drives the reading upstream roller 5, the lead roller 6, the reading downstream roller 7, and the paper ejection roller 12.

By causing the separation motor 820 to rotate normally, the CPU 801 rotates the paper feed roller 1, separation roller 2, pull-out roller 3, and registration roller 4 so as to convey the document downstream in the conveyance direction. By rotating the reading motor 821 in the forward direction, the CPU 801 rotates the upstream reading roller 5, the lead roller 6, the downstream reading roller 7, and the paper ejecting roller 12 so as to convey the document downstream in the conveying direction. By reversing the reading motor 821, the CPU 801 rotates the paper ejection roller 12 so as to convey the document to the reversing path 19.

Separation motor 820 and reading motor 821 are pulse motors. The CPU 801 controls the number of driving pulses of the separation motor 820 and the reading motor 821 according to the detection results of the document on the conveyance path by the post-separation sensor 15, the registration sensor 17, the read sensor 18, and the paper ejection sensor 11. Transport the original. The CPU 801 can monitor the position of the document being transported based on the detection results from the post-separation sensor 15, the registration sensor 17, the lead sensor 18, and the discharge sensor 11. Further, the CPU 801 calculates the length of the document being transported in the transport direction (original length) based on the document detection timing of the post-separation sensor 15, the registration sensor 17, and the read sensor 18, and the number of drive pulses of the separation motor 820. can be detected. That is, the CPU 801, the post-separation sensor 15, the registration sensor 17, the read sensor 18, and the separation motor 820 have a document length detection function.

The CPU 801 controls the operations of the LED 203 and the image reading sensor 208 of the optical scanner unit 202 to realize a document image reading function. Specifically, the CPU 801 causes the LED 203 to emit light based on the timing when the read sensor 18 detects the document, and irradiates the document passing the reading position with light. The image reading sensor 208 receives light reflected by the original and outputs image data. The CPU 801 uses the tilt detection unit 830 and the image processing unit 833 to perform tilt correction based on the image data that is the result of reading by the image reading sensor 208. The image data after the tilt correction is transmitted from the image processing section 833 to the second controller 300 via the image line 353. The CPU 801 transmits a vertical synchronization signal that serves as a reference for the leading edge of image data and a horizontal synchronizing signal that serves as a reference for the leading edge of one line of pixels to the second controller 300 via the communication line 354.

The second controller 300 includes a CPU 901, a ROM 902, a RAM 903, an image processing section 905, and an image memory 906. The CPU 901, ROM 902, RAM 903, image processing unit 905, and image memory 906 are communicably connected via bus B2. An operation unit 904 is also connected to bus B2. The CPU 901 controls the operation of the entire system including the image reading apparatus 1000 by executing a computer program stored in the ROM 902. At this time, RAM 803 provides a work area.

The CPU 901 transmits and receives data regarding image reading control to and from the CPU 801 via the communication line 354. The image processing unit 905 acquires image data from the image processing unit 833 via the image line 353. The image processing unit 905 performs predetermined processing on the acquired image data and stores it in the image memory 906. The operation unit 904 is a user interface that includes an input device and an output device. Input devices include input keys, key buttons such as numeric keys, touch panels, and the like. Output devices include displays and speakers. The CPU 901 receives input such as instructions from the operation unit 904 . The CPU 901 performs various notifications and input assistance by displaying a screen on the operation unit 904.

FIG. 3 is an explanatory diagram of a method for detecting the length (document width) of a document placed on the document tray 30 of the ADF 100 in a direction perpendicular to the transport direction (main scanning direction). The document tray 30 is provided with a pair of document guide plates 31 . The document guide plate 31 regulates the sides of the documents placed on the document tray 30 in the main scanning direction and arranges the document bundle S. The document guide width detection sensor 10 detects the distance between the pair of document guide plates 31 (document guide width A). The CPU 801 obtains the document guide width A based on the detection result of the document guide width detection sensor 10. Normally, a user places a document on the document tray 30 and adjusts the document guide plate 31 to the width of the document. Therefore, the document guide width A becomes equal to the document width. That is, the CPU 801 can detect the document width of the document placed on the document tray 30 based on the detection result of the document guide width detection sensor 10 . In this way, the document guide width detection sensor 10 has a document width detection function.

(Tilt detection and tilt correction)
The detection and correction of the tilt of a document will be explained. Even after the skew has been corrected by the registration rollers 4, the document may skew again before it is conveyed to the reading position. By feeding the document obliquely, the optical scanner unit 202 reads the document in an inclined state with respect to the direction (main scanning direction) in which one line of images is read. In order to correct an image read in such a tilted state, tilt detection and tilt correction of the document are performed.

The tilt detection unit 830 acquires image data from the image reading sensor 208. As described above, the image data includes images around the document in addition to the document image. The tilt detection unit 830 extracts the shadow of the edge of the document from the image data, and uses the shadow to detect the leading edge and trailing edge of the document in the transport direction. The tilt detection unit 830 detects the amount of tilt of the document based on the leading edge and trailing edge of the document.
In addition, the tilt detection unit 830 detects the lateral edge of the document perpendicular to the transport direction based on the shadow of the edge of the document extracted from the image data. The tilt detection unit 830 detects the position (for example, coordinates) of the center of rotation based on the leading edge and the lateral edge of the document. The rotation center is the center position when rotating the original image during tilt correction.

The CPU 801 acquires the amount of tilt of the document and the position of the center of rotation from the tilt detection unit 830. The CPU 801 sets the acquired tilt amount of the document and the position of the center of rotation in the image processing unit 833. The image processing unit 833 processes the image data by affine transformation based on the position of the rotation center and the amount of inclination set by the CPU 801, and rotates the read document image.
This corrects the tilt of the original image. In this embodiment, a case will be described in which the inclination of the document image can only be corrected to less than 5 degrees due to the length of the image reading sensor 208 in the main scanning direction and the image memory capacity.

The image processing unit 833 uses affine transformation to calculate pixel positions (main scanning (X), sub-scanning (Y)) for correcting the angle θ according to the amount of inclination. The general formula for affine transformation is shown below.
X = xcosθ - ysinθ + x0
Y = xsinθ + ycosθ + y0
X: Pixel position after correction in the main scanning direction Y: Pixel position after correction in the sub-scanning direction x: Pixel position in the main scanning direction before correction y: Pixel position in the sub-scanning direction before correction x0: Pixel position in the main scanning direction Parallel movement amount (main scanning tilt correction reference position)
y0: Amount of parallel movement in the sub-scanning direction (sub-scanning tilt correction reference position)
θ: Angle based on the inclination calculated from the leading edge of the document

x0 and y0 are movement amounts for translating the tilt-corrected image data (original image). The parallel movement of the image data makes it possible to match the output positions of the leading edge and the lateral edge of the original image. The above affine transformation formula is a general formula, and when realized in an integrated circuit, the following calculation formula is used with cos θ≈1.
X = x - ytanθ + x0
Y = xtanθ + y + y2
X: Pixel position after correction in the main scanning direction Y: Pixel position after correction in the sub-scanning direction x: Pixel position in the main scanning direction before correction y: Pixel position in the sub-scanning direction before correction x0: Pixel position in the main scanning direction Parallel movement amount (main scanning tilt correction reference position)
y0: Amount of parallel movement in the sub-scanning direction (sub-scanning tilt correction reference position)
tanθ: Amount of tilt of the original

In this embodiment, the tilt is detected from the shadow of the leading edge of the document, and the tilt is corrected by rotating the image by affine transformation using the rotation center as a reference. The tilt detection and tilt correction are not limited to this method, and other methods may be used as long as the position of the center of rotation can be obtained.

(Rotation center position abnormality determination)
FIG. 4 illustrates a state in which the document is skewed. FIG. 4 shows a state in which a document having document width A passes through the reading position at an angle θ with respect to the main scanning direction. FIG. 5 is an explanatory diagram of the detection result of the lateral edge of the document. FIG. 5A shows a state in which the leading edge, lateral edge, and center of rotation of the document are normally detected. FIG. 5B shows a state in which the leading edge of the document is detected normally, but the lateral edge and the center of rotation are erroneously detected. A user places originals having a width A on the original tray 30 and aligns the originals using the original guide plate 31. In this case, the interval between the document guide plates 31 represents the document width A.

As shown in FIG. 4, when the document is tilted and the trailing edge is located between the document guide plates 31, the position of the apex of the leading edge of the document, which is the center of rotation for tilt correction, is It is considered that the position protrudes outward by α in the scanning direction. If dust or scratches adhere to the read roller 6 or the scanning glass 201 at the reading position, the image of the dust or scratches will be included in the read document image. Images of dust or scratches may cause false detection of the lateral edges of the document. Therefore, if the image data includes images of dust or scratches, the tilt detection section 830 may not be able to properly detect the center of rotation. For example, the center of rotation is erroneously detected at a position that is a predetermined distance (α) or more away from the position of the document guide plate 31 in the main scanning direction (FIGS. 5(a) and 5(b)).

Here, α is expressed by the following formula, where the original width A and the original length L are assumed (see FIG. 4).
A+α=B+C
= Asin(180-90-θ)°+L/tan(180-90-θ)°
α = Asin(180-90-θ)°+L/tan(180-90-θ)°-A

As mentioned above, the document length L is determined by counting the number of driving pulses of the separation motor 820 and the reading motor 821 from when the post-separation sensor 15, the registration sensor 17, and the read sensor 18 detect the document until they no longer detect the document. It is calculated by The CPU 801 acquires the document guide width A (document width A) using the document guide width detection sensor 10 before starting document conveyance, and acquires the document length L during document conveyance. Further, the CPU 801 obtains the amount of tilt θ of the document detected by the tilt detection unit 830 from the reading result (image data) of the document image. The CPU 801 can calculate the value of α for each document from the above equation using the obtained document guide width A, document length L, and tilt amount θ.

The CPU 801 can determine whether the position of the rotation center is normal by comparing the value of α calculated using the above formula with the position of the rotation center during tilt correction. Specifically, the CPU 801 determines that it is normal if the rotation center position is inside α (in the direction toward the center of the document) from the position of the document guide plate 31 in the main scanning direction; If so, it can be determined that there is an abnormality. α becomes a reference value for determining whether or not the position of the center of rotation is normal. The reference value is set within a predetermined distance range (normal range) from the position of the document guide plate 31 in the main scanning direction.

Note that in this embodiment, the value of α is calculated using the above formula assuming the position of the trailing edge of the document, but the value is not limited thereto. For example, when the image reading apparatus 1000 is manufactured, the relationship between the document size and the amount of inclination of the document may be detected and stored in a memory within the first controller 310, and the value of α may be determined for each document size. Further, the value of α may be set to a predetermined value in advance.

(Tilt correction processing)
FIG. 6 is a flowchart showing image reading processing including tilt correction processing. The user places a document on the document tray 30 and instructs the operation unit 904 to start reading the document image. At this time, the user regulates the main scanning direction of the document placed on the document tray 30 using the document guide plate 31 . An instruction to start reading is input from the operation unit 904 to the CPU 901 of the second controller 300 . The CPU 901 transmits an image reading process execution command to the CPU 801 of the first controller 310 in response to the instruction to start reading. The CPU 801 receives an image reading process execution command from the CPU 901 and starts the image reading process. In order to place the original on the original tray 30, the CPU 801 reads the original image by skimming.

The CPU 801 controls the separation motor 820 and the reading motor 821 to start feeding the original placed on the original tray 30 (S101). The CPU 801 starts reading the original image by operating the optical scanner unit 202 according to the timing when the read sensor 18 detects the original (S102). The image reading sensor 208 outputs image data as a reading result.

The tilt detection unit 830 detects the amount of tilt of the document and the position of the center of rotation based on the image data output from the image reading sensor 208. The CPU 801 acquires the amount of tilt and the position of the center of rotation from the tilt detection unit 830 (S103). The CPU 801 sets a range (normal range) in which the position of the rotation center is normal during tilt correction, by the process described in the above-described rotation center position abnormality determination (S104). The normal range is expressed, for example, by the above reference value.

The CPU 801 compares the position of the rotation center obtained from the tilt detection unit 830 with a normal range (S105). If the position of the center of rotation is within the normal range (S105: Y), the CPU 801 determines that the edge of the document is normally detected, and determines that normal tilt correction can be performed. In this case, the CPU 801 causes the image processing unit 833 to execute tilt correction processing (S109). If the position of the center of rotation is not within the normal range (S105:N), the CPU 801 determines that the edge of the document has been erroneously detected, and determines that normal tilt correction cannot be performed. In this case, the CPU 801 does not cause the image processing unit 833 to perform tilt correction processing (S106). Note that the image processing unit 833 performs other predetermined image processing on the image data, regardless of whether or not the tilt correction processing is performed.

The CPU 801 causes the image processing unit 833 to transmit image data to the image processing unit 905 of the second controller 300, whether or not the image processing unit 833 executes the tilt correction process ( S107). After transmitting the image data, the CPU 801 determines whether or not there is a document in the document tray 30 based on the detection result of the document presence detection sensor 14 (S108). If there is a document (S108: Y), the CPU 801 will perform the processes from S101 onwards again. If there is no original (S108:N), the CPU 801 ends the image reading process.

In the above process, regardless of the amount of tilt of the document, if the horizontal edge of the document is erroneously detected, tilt correction is not performed. Note that when the lateral edge of the document is erroneously detected, a process may be performed to move the center of rotation between the document guide plates 31 to perform tilt correction. Further, the image reading apparatus 1000 may read the document image by notifying the user to change the orientation of the document, for example, and hiding the dust on the read roller 6 from the document whose orientation has been changed. Furthermore, if the edge of the document is erroneously detected, the CPU 801 may cause the CPU 901 of the second controller 300 to display on the operation unit 904 that tilt correction will not be performed, and prompt the user to read the image again.

(Other examples of tilt correction processing)
FIG. 7 is another flowchart showing the image reading process including the tilt correction process. Similar to the process in FIG. 6, this process is executed in response to a user's instruction to start reading from the operation unit 904. The processing in S201 to S205 is the same as the processing in S101 to S105 in FIG. 6, so a description thereof will be omitted.

If the position of the center of rotation obtained from the tilt detection unit 830 is within the normal range (S205: Y), the CPU 801 determines that the edge of the document has been detected normally, and can perform normal tilt correction. It is determined that In this case, the CPU 801 causes the image processing unit 833 to execute tilt correction processing (S208). The CPU 801 causes the image processing unit 833 to transmit the processed image data to the image processing unit 905 of the second controller 300 (S209). After transmitting the image data, the CPU 801 determines whether or not there is a document in the document tray 30 based on the detection result of the document presence detection sensor 14 (S210). If there is a document (S210: Y), the CPU 801 will perform the processes from S101 onwards again. If there is no original (S210:N), the CPU 801 ends the image reading process.

If the position of the center of rotation obtained from the tilt detection unit 830 is not within the normal range (S205: N), the CPU 801 determines that the edge of the document has been erroneously detected, and normal tilt correction cannot be performed. It is determined that In this case, the CPU 801 performs interruption processing (S206). The CPU 801 transmits a reading interruption signal to the CPU 901 of the second controller 300 through interruption processing. Further, the CPU 801 discharges all the documents being transported to the transport path of the ADF 100 through the interruption process. The CPU 801 determines that the cause of the rotation center position not being within the normal range is dust or scratches on the lead roller 6 or the scanning glass 201, and causes the CPU 901 of the second controller 300 to display a cleaning screen on the operation unit 904 urging cleaning. (S207). FIG. 8 is an exemplary diagram of the cleaning screen. The user performs cleaning according to this cleaning screen and then instructs the image reading process again.

In the above processing, tilt correction is performed when the rotation center is within the normal range, and is not performed when the rotation center is outside the normal range. Further, if the rotation center is outside the normal range, the user is instructed to clean the lead roller 6 and the panning glass 201. After cleaning, the user can obtain a reading result of the original image in which the tilt has been correctly corrected by reading the original again.

As described above, the image reading apparatus 1000 of the present embodiment can prevent inaccurate tilt correction of image data by not performing tilt correction when the edge of the document is erroneously detected. When not performing tilt correction of image data, the image reading apparatus 1000 may perform tilt correction after moving the rotation center position. Furthermore, if the image data is not tilted, the image reading apparatus 1000 may prompt the user to read the image again or instruct the user to clean the lead roller 6 and the panning glass 201.

Claims (3)

a document tray on which documents are placed;
a document guide that regulates the widthwise position of the document placed on the document tray;
a conveyance means for conveying the document placed on the document tray;
reading means for reading the original document being transported by the transporting means;
From the reading result of the document by the reading means, the amount of inclination is detected based on the leading edge and trailing edge of the document in the conveying direction, and the amount of inclination is detected based on the leading edge in the conveying direction and the lateral edge of the document in the width direction. tilt detection means for detecting the intersection as a rotation center position for correcting the tilt of the document;
a correction means for correcting the inclination of the read result by rotating the read result by the inclination amount with respect to the rotation center position;
Based on the position of the document guide and the rotation center position, it is determined whether the rotation center position is within a normal range in which tilt correction is possible, and if the rotation center position is within the normal range, the tilt correction is performed. A control means for outputting a reading result, and outputting the reading result without the tilt correction when the reading result is not within the normal range,
Manuscript reading device. The control means determines that the lateral edge is normally detected when the rotation center position is within the normal range, and outputs the reading result after performing the tilt correction, and when the rotation center position is not within the normal range. determining that the lateral edge is erroneously detected and outputting the reading result without the tilt correction;
The document reading device according to claim 1. The control means may perform the reading without performing the tilt correction when the rotation center position in the width direction is outside the normal range that is a predetermined distance range in the width direction from the position of the document guide. Characterized by outputting results,
The document reading device according to claim 1 or 2.

Images