JPH10304145A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent such trouble as a shift, distortion, and fading of a read image due to the turning of a document during a scan of its document surface etc., with simple constitution. SOLUTION: The image reader reads the document mounted faceup on an original platen 7 by optically scanning it, and has a distance measuring mirror 4 which is arranged obliquely on the original platen 7 and a line sensor(image pickup means) 11 which reads the document surface and a document end surface reflected in the mirror 4 at the same time while scanning them. Then a control part(distance variation detecting means and abnormality detecting means) 100 of the image reader detects variation in the distance from the line sensor 11 to the document surface during the scan of the document surface by the line sensor according to data on the document end surface and judges that the document is turned when the distance variation is large, thereby detecting abnormality.

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 for reading an image of a book original by setting a book original such as a book upward on an original base and optically scanning from above the original base. It relates to a reader.

[0002]

2. Description of the Related Art In a conventional general image reading apparatus, a document is set on a platen glass with the surface of the document to be read turned downward, pressed down from above by a document pressing plate. Therefore, when reading a book original such as a book continuously while turning pages, the book original must be turned over to turn over the pages, and then turned over again and set on the platen glass. Due to such poor operability, it is difficult to quickly read the book document, and there is a risk that the book document may be damaged when the book document is turned over.

In order to solve such a problem, in recent years, an image reading apparatus in which an original is set on an original plate with the original surface to be read facing upward, and an original image is read by optical scanning from above the original plate. (For example, see Japanese Patent Application Laid-Open No. 8-242347).

[0004]

The image reading apparatus in which the reading surface is set upward is configured so that the original is not pressed down from above by the original pressing plate, so that the operation of continuously reading the book original while turning the pages is performed. While it can be performed easily and quickly, it is also possible for the operator to turn the original page during reading. For this reason, if the page is turned during the pre-scan or the main scan and the document height changes, the following problem occurs. In other words, a detection error of the document size occurs, a black frame remains or is lost in the read image, a detection error of the background luminance occurs, the image is fogged or fogged, and a detection error of the document height occurs. As a result, the scanned image may be distorted or out of focus.

Here, an image reading apparatus has been proposed which detects a change in luminance and detects an abnormality during scanning. However, in this method, it is not possible to detect a change in height up to a document surface without a change in luminance. Can not. Although an image reading apparatus that detects an error during scanning by detecting a displacement of a document has been proposed, this method requires a mechanism for constantly monitoring a document image, which leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems associated with the prior art described above, and has a problem such as displacement, distortion, and inadvertence of a read image due to turning of the original while scanning the original surface. It is an object of the present invention to provide an image reading apparatus which can prevent the occurrence of the image with a simple configuration.

[0007]

According to a first aspect of the present invention, there is provided an image reading apparatus for reading a document placed upward on a document table by optically scanning the document. A mirror disposed at an angle on the platen, an imager for reading simultaneously while scanning a document surface of the document placed on the platen and a document end surface reflected on the mirror; Distance change detection means for detecting a change in the distance from the image pickup means to the document surface based on the data of the document end face, and the distance change detection means for detecting the change in the distance between the document surface and the image pickup means. An image reading apparatus comprising: an abnormality detection unit that detects an abnormality based on a distance change amount.

In this image reading apparatus, the image pickup means scans the document surface and the document end face reflected on the mirror simultaneously while scanning, and the distance change detecting means detects the distance from the image pickup means to the document face based on the data of the document end face. Detect changes. The abnormality detecting means detects an abnormality based on the distance change amount detected by the distance change detecting means during scanning of the document surface. For example, if a page is turned while reading an image of a book original, the original surface changes from the position at the start of reading and the distance from the image pickup means to the original surface changes. The means detects the amount of change in the distance, and when the amount of change in the distance is larger than a predetermined value, the abnormality detecting means detects an abnormality. Therefore, it is possible to prevent the occurrence of problems such as deviation, distortion, and inattention of the read image due to turning of the original during scanning of the original surface. In addition, since the imaging unit that reads the original surface also serves as a unit that measures the height of the original surface,
The above-mentioned problem can be prevented with a simple configuration.

According to a second aspect of the present invention, there is provided an image reading apparatus for reading a document placed upward on a document plate by optically scanning the document, wherein Imaging means for reading while scanning the original surface of the placed original, a plurality of distance measuring means for measuring a distance to a fixed point set on the original surface, and measurement by the plurality of distance measuring means Distance change detection means for detecting a change in the distance from the imaging means to the document surface based on the respective distance data; and a distance change detected by the distance change detection means during scanning of the document surface by the imaging means. And an abnormality detecting means for detecting an abnormality based on the amount.

In this image reading apparatus, the image pickup means reads the document surface while scanning it, a plurality of distance measuring means measures the distance to a fixed point set on the document surface, and the distance change detecting means reads the distance measuring means. The change of the distance from the image pickup means to the document surface is detected based on each distance data measured by the above. The abnormality detecting means detects an abnormality based on the distance change amount detected by the distance change detecting means during scanning of the document surface. For example, if the page is turned while reading the image of the book original,
Although the document surface changes from the position at the start of reading and the distance from the imaging means to the document surface changes, the distance change detection means detects the amount of change in each distance measured by each distance measuring means, and the distance change When the amount is larger than the predetermined value, the abnormality detecting means detects the abnormality. Therefore, it is possible to prevent the occurrence of problems such as deviation, distortion, and inattention of the read image due to turning of the original during scanning of the original surface. Also, it is only necessary to provide a simple distance measuring means such as a distance sensor separately from the imaging means for reading the document surface,
The configuration of the image reading apparatus is not complicated, and an increase in cost can be suppressed.

Further, if the abnormality detecting means displays a predetermined warning on the display unit when an abnormality is detected, the convenience of the operator is enhanced.

[0012]

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

First Embodiment The image reading apparatus according to the first embodiment detects an abnormality when a page is turned while reading an image of a book original, and detects an abnormality on the surface of the original. This makes it possible to prevent the occurrence of problems such as displacement, distortion, and inattention of a read image due to turning of a document during scanning.

[0014] In the present specification, "left-bound document"
The term "right-bound document" refers to a document in which the left end of the document group is bound with staples or glue when the first page of the document is facing up. A document whose right end is bound by staples or the like. Further, FIG. 2A or FIG.
In the state shown in (A), the method of turning the right side page of a document opened upward and facing the left side is referred to as “left page turning”. Conversely, the method of turning the left side page to the right side is referred to as “turning the left page”. "Right page turning".

<< Overall Configuration >> FIG. 1 is a perspective view showing the overall configuration of the image reading apparatus. Platen 7 of image reading device
On the upper side, a book original such as a book or a file, which is a subject, is placed facing upward in a spread state. Above the original platen 7, there is provided an image pickup means for reading a spread surface (original surface) of the original by optical scanning. Reading unit 2 having corresponding line sensor
Is provided. A predetermined space is set between the document table 7 and the reading unit 2, and a work space is formed by this space.

The image reading apparatus has a document table 7.
A lighting unit 3 arranged at the back side of the upper side to illuminate the original on the original platen 7; an operation panel 1 (corresponding to a display unit) for setting image reading conditions and the like and displaying the state of the apparatus; Distance measuring mirror 4 that is located at the back of the camera and captures the shape of the document edge
(Corresponding to a mirror). The distance measuring mirror 4 is disposed at an end in the photographing range along the sub-scanning direction and obliquely with respect to a horizontal plane. The shape of the document end face reflected on the distance measuring mirror 4 is read by the line sensor of the reading unit 2 and is converted into height position data of the document surface.

The original mounting surface of the original platen 7 is colored darker than the background color of a general original, and when an original is read with the original mounting surface as a background, the original surface and the original mounting surface are distinguished. I can do it.

FIGS. 2A and 2B are schematic structural views showing the image reading apparatus as viewed from the front and side, respectively. As shown in FIG. 2A, a reading unit 2 includes a CCD line sensor 11 in which a plurality of image pickup devices are arranged in a line from the front side of the apparatus to the back side (main scanning direction), and a line image of a document surface. And an optical system including an imaging lens 12 that projects onto the sensor 11 and forms an image on the imaging element. The line sensor 11 scans the image on the document surface in a sub-scanning direction (direction indicated by an arrow) orthogonal to the main scanning direction on an image forming plane or a focal plane on which the image on the document surface is formed. Read. In addition, the imaging lens 12
A lens driving device (not shown) is provided so as to be movable in the optical axis direction. The lens driving device is moved in accordance with the height position of the document surface obtained by detecting the height position described later, and is always focused on the line sensor 11. Forms an image on the surface of the original.
The document 10 placed on the platen 7 is, for example, a book or a file that is bound at one end, and when opened to the left and right, each page has a spatially curved pillar shape.

As shown in FIG. 2B, a part of the CCD line sensor 11 reads an image of the upper end portion of the document reflected on the distance measuring mirror 4. The distance measuring mirror 4 extends in the left-right direction (sub-scanning direction) on the back side of the document table, also serves as a document positioning stopper, and is inclined at an angle of 45 degrees with respect to the document mounting surface of the document table 7 Have been. The upper end of the document 10 is pressed against the lower end of the distance measuring mirror 4, and the document 10 is positioned by centering the document 10 on the center of the document table 7. In addition, a reference plate for pressing the upper end of the document 10 can be separately provided in front of the distance measuring mirror 4.

The end face image of the document 10 transferred to the distance measuring mirror 4 is projected by a lens 12 together with the document surface.
The surface of the document 10 placed on the document table 7 in this manner,
Since the end face of the document 10 reflected on the distance measuring mirror 4 is simultaneously read, the configuration is simplified and the operability is excellent. The line sensor 11 has a length sufficient to read the projected image of the document surface and the end surface, and simultaneously reads the image of the document surface and the end surface by scanning movement. In the present embodiment, the case where a line sensor is used has been described, but an area sensor may be used instead.

As shown in FIG. 2B, the image reading device includes a scan control unit for controlling a reading operation such as a preliminary scanning operation and a main scanning operation of the CCD line sensor 11, and a processing unit for processing the read image signal. Control unit 10 including an image signal processing unit, an operation panel control unit, etc.
Has zero. Further, an interface unit 30 for outputting image data input from the control unit 100 to an external desired output device (for example, a printer, a computer, or the like) is also included.

<< Structure of Driving Mechanism of Reading Unit 2 >> FIG.
FIG. 3 is a perspective view illustrating a configuration of a drive mechanism of a reading unit. CC
The scanner 50 to which the D line sensor 11 is attached
The scanner is slidably supported by shafts 51 and 52 and driven by a scanner motor 53 including a stepping motor via a belt 54 and a feed gear shaft 55 to read an image. The scan speed changes according to the height of the document and the copy magnification, and the scan length changes according to the size of the document. The scanner / home sensor 56 is the scanner 5
The scanner limit sensor 57 is a sensor for checking an overrun of the scanner 50. Each of the sensors 56 and 57 is configured by a photo sensor or the like, and detects a light-shielding plate 58 attached to the scanner 50, thereby confirming a reference position and checking for overrun.

<< Outline of Reading Operation >> An image is read by the CCD line sensor 11 mounted on the scanner 50.
Is performed by scanning the original surface, but before performing the image reading scan (main scan), a preliminary scan is performed to detect various states of the original required for reading. In the preliminary scan, the document size, document background density,
Detection of the document height and the like is performed. The document size is used for setting the reading range, the document background density is used for automatic exposure, and the document height is used as data for auto focus and distortion correction at the time of main scanning.

<< Detection of Original Size and Original Surface Height >>
When the original 10 placed on the original platen 7 is placed upward in a spread state, the surface of the original generally has a shape that is spatially curved in the height direction. Therefore, the position in the height direction of the document surface at each position in the sub-scanning direction is detected, and the distortion of the read image and the focus adjustment of the image formed on the line sensor 11 are detected in accordance with the height. Need to do.

FIG. 4A is a diagram showing the principle of the document surface height detection process used in the present embodiment. When the original 10 is placed at a predetermined position, a mirror image 10 'of the upper end surface of the original 10 is formed by the distance measuring mirror 4, and the mirror image 10' of the upper end surface of the original 10 is continuous with the original image on an extension of the image of the original platen 7. Formed. In the process of detecting the height of the document surface, the image 10 ′ of the document end face imaged on the distance measuring mirror 4 is read by the line sensor 11.
To obtain the distribution of the height position of the document surface. In FIG. 4A, the reading range of the line sensor 11 is indicated by a dashed-dotted line 16, and the pixels of the CCD line sensor 11, that is, the addresses of the imaging elements are indicated by 1 to n in order from the left in the drawing.

FIG. 4B is a diagram showing image data when the original 10 is read in the state of FIG. In the figure, a is an image of the document surface, b is an image of the document table 7, c is an image of the background portion reflected on the distance measuring mirror 4, d is an image of the document end face reflected on the distance measuring mirror 4, and e is the document. Are shown. The image d of the document end surface is read such that a high portion is slightly curved upward due to a change in the height position of the document surface. The original surface and the end surface of the original are illuminated by the illumination unit 3 and are generally white, so that they are read in white as a whole. On the other hand, in the document table 7 which is darker than the background of the document and in the portion of the distance measuring mirror 4 where the document end face is not shown, the amount of light incident on the line sensor 11 is reduced and the image is read in black. Here, the document size is
It is detected by detecting the boundary around the original using the luminance difference between the original image a and the original table image b. The manuscript height is
It is detected by detecting the boundary between the document end face image d reflected on the distance measuring mirror 4 and the background image.

FIG. 5 is a diagram showing an output example of one line in the main scanning direction read by the CCD line sensor 11. Note that the horizontal axis represents the address of the image sensor of the line sensor 11 (the left side is the rear side, the right side is the front side), and the vertical axis is the sensor surface illuminance.

In the drawing, reference numeral c denotes an image of a background portion reflected on the distance measuring mirror 4, reference numeral d denotes an image of an end face of the document reflected on the distance measuring mirror 4, reference numeral denotes the entire distance measuring mirror 4, and reference Represents the area of the image b on the document table on the image sensor.

L1 indicates a predetermined illuminance threshold for determining whether the image is a document image or another image. Also,
n1 is a minimum address value of the image sensor at which the illuminance passes the threshold value L1 from the black side to the white side, that is, a value indicating a position where an upper edge (original surface) in the image d of the original end surface is formed. n5 is an address value of the image sensor corresponding to the document alignment reference, and is a fixed value. n2 is n
The maximum address values n3 and n4 of the image sensor that passes the threshold L1 from the white side to the black side at 5 or less are the minimum and maximum addresses of the image sensor that passes the threshold L1 at n5 or more. n2 is a value indicating the position where the lower edge (back side of the document) in the image d of the document end surface is formed.

"N1-n5" is the number of pixels corresponding to the height of the upper edge (original surface) of the original end surface, and "n2-n"
“5” is the number of pixels corresponding to the height of the lower edge (original back surface) of the original end surface. By calculating the number of these pixels along the sub-scanning direction of the document and converting it into a length, the height distribution and the document size can be obtained. That is, when the line sensor 11 moves in the left-right direction (sub-scanning direction), n1 is set according to the height position of the document surface at each position in the sub-scanning direction.
Is changed, whereby the distribution of the height position of the document surface in the document left-right direction can be obtained. In addition, since the outputs of the image sensor all become low, it is possible to detect the horizontal dimension of the spread original.

Note that "n4-n5-α" is the number of pixels corresponding to the size of the document in the front-back direction. α is the amount of curvature of the front edge of the document caused by a change in the height position of the surface of the document, and is a value determined by the document height (n2−n1) in this portion. Therefore, the height position of the document surface can be detected from the value of α.

<Detection of Original Background Luminance> FIG. 6 is a diagram showing a luminance histogram created from image data for one line in the main scanning direction of a document read by the CCD line sensor 11. The frequency of the peak on the higher luminance side in the histogram is obtained, and the lower luminance value having half the frequency is set as the original background luminance of the line.
A value obtained by subtracting a constant value from the original background luminance is set as a threshold value of the character portion luminance.

FIG. 7A is a diagram showing the distribution of the original background luminance for one page of the original. The central portion of the document has a low height, a long distance from the illumination unit 3 and the reading unit 2 and a surface inclination, so that the background luminance of the document is low.
In addition, in addition to the above-described reason that the background brightness of the document is low at the center portion at the left and right ends of the document, the brightness of the background of the document is similarly low because the brightness is greatly reduced due to fading or the like.

FIG. 7B is a diagram showing the distribution of character frequencies in a document. In the text portion in which the contents of the manuscript are written, there are many low-luminance parts such as characters and photographs, and the frequency of characters increases. At the center of the document, at the breaks of the paragraphs, and at the left and right margins, since the document content is not written, the character frequency has a small value. In addition, the character frequency also has a low value between lines in a vertically written original.

FIG. 8 is a conceptual diagram showing the distortion correction. The distortion is corrected for the read signal by controlling the magnification in both the main scanning direction and the sub-scanning direction.

<< Configuration of Control Unit >> FIG. 9 is a block diagram showing the overall configuration of the control unit of the present apparatus. The control unit 100 is 2
Each of the CPUs 101 and 102 is provided with ROMs 111 and 112 storing a program and RAMs 121 and 122 serving as work areas for executing the program.

The CPU 101 receives signals from various operation keys of the operation panel 1 and performs processing for controlling display output to the display unit of the operation panel 1, adjusting timing as a whole, and setting operation modes. . The initial mode and the user mode of the operation panel 1 are set in the NVRAM 127.
Is stored in

The CPU 102 controls each unit of the image signal processing unit 20 for detecting the size / height and the background luminance, and controls the driving of the scanning system.

The interface unit 30 outputs the image data from the image signal processing unit 20 to an external device via a general-purpose interface. The control unit 100 includes a ROM 113 and a RAM of an external device via the interface unit 30.
123.

<< Image Signal Processing Unit 20 >> FIG. 10 is a block diagram showing the configuration of the image signal processing unit 20 shown in FIG. The CPU 102, the ROM 112, the RAM 122, and the CCD 11 correspond to those shown in FIG.

An image reading synchronization signal is supplied from the CPU 102 to each block. The CCD 11 scans a document in the main scanning direction and generates a document reading signal. The generated signal is converted into a digital signal by the A / D converter 22 and sent to the image processor 23. The image processing unit 23 performs processing such as image quality correction such as shading correction, MTF correction, and gamma correction, and distortion correction on the input signal, and then converts the input signal into the interface unit 30 as image data.
Output to

The image monitor memory 24 stores one line of image data in accordance with an instruction from the CPU 102, and detects the luminance of the document and the height to the document surface based on the stored image data. The CPU 102 also sets parameters for the image processing unit 23 and performs scan control by driving a scanner motor.

In the first embodiment, the control unit 100 corresponds to distance change detecting means for detecting a change in the distance from the line sensor 11 to the document surface based on the data of the document end surface read by the line sensor 11, and This corresponds to abnormality detection means for detecting an abnormality based on the detected distance change amount during scanning of the document surface by the line sensor 11.

<< Detection of Change in Height of Document Surface >> Next, a procedure for detecting a change in height of the document surface will be described with reference to FIGS. 11 and 12.
This will be described with reference to FIG. FIG. 11 is a diagram for explaining a procedure for detecting a change in the height of the document surface, and FIG. 12 is a flowchart showing a procedure for detecting a change in the height of the document surface during one scan (during the preliminary scan and the main scan). is there.

In FIG. 11, the reference position on the original is Y
0, Y1, Y2 and Y3. Here, in order to prevent erroneous detection, the reference position is set to two for each of the left and right pages except for the both ends and the center where the height of the document changes rapidly.
The location is used as a reference point.

As shown in the flowchart of FIG.
When receiving a scan request from the CPU 101 in step S1, the PU 102 first initializes a height change detection flag F (S2). Next, it is determined whether or not the current scanning position Y in the sub-scanning direction is larger than the document position Y0 (see FIG. 11) (S3). The document position Y0 is a predetermined position, and is a position where the change in the height of the document surface is stable. After the current scanning position Y in the sub-scanning direction becomes larger than the document position Y0 (S3 "Yes"), the distance H0 to the document surface is calculated from the image data and stored in the RAM 122 (S4).

Next, the timer is started after being initialized (S5), and after a lapse of a predetermined time Ts (S6 "Ye").
s "), the distance Hn (n = 1) to the document surface is calculated from the image data and stored in the RAM 122 (S7). CPU
102 compares the current measurement value (H1) with the immediately preceding measurement value (H0) performed immediately before (S8). If the difference between the two measured values greatly changes beyond the preset value Hs (S8 "Yes"), it is determined that the distance from the line sensor 11 to the document surface has changed greatly due to page turning or the like. An error is detected and notified to the CPU 101 (S10). If the difference between the two measured values is smaller than the set value Hs (S8 "No"), it is determined whether the scan position Y is larger than the document position Y1 (S9).

Until the scan position Y reaches the document position Y1 (S9 "Yes"), the processing of steps S5 to S10 is repeated. That is, the distance Hn to the document surface is measured at regular time intervals Ts (S5 to S7), and each time the distance Hn is compared with the immediately preceding measurement value Hn-1 (S8). If the value has greatly changed beyond the set value Hs, an error is detected and notified to the CPU 101 (S8: “Y”).
es ", S10).

While the scan position Y is located at the central portion of the original (between Y1 and Y2) where the distance to the original surface may vary greatly, distance measurement to the original surface is not performed, and the scan position Y is set to the original surface. After the height of the original reaches the original document position Y2 at which the height becomes stable again (S9 "Yes", S11 "Yes"), the distance measurement to the original surface is restarted.

That is, when the scan position Y reaches the document position Y2 (S11 "Yes"), the height change detection flag F
= 0 (S12 "Yes"), the flag F is set to 1 (S13), and the distance measurement to the document surface is restarted (S4 to S10) until the scan position Y exceeds Y3 (S14). "Yes"), the processing of steps S5 to S10 is repeated, and if the measured distance change is large, error detection is performed.

When detecting an error, the CPU 102 transmits the occurrence of the error to the CPU 101, and
The PU 101 issues an instruction to stop the operation of each unit, and displays error information, a rereading method, and the like on the operation panel 1.

FIG. 13 is a flowchart showing error detection when the height of the document changes from the end of the preliminary scan to the start of the main scan.

First, during the preliminary scan, the height Hp of the document surface at a plurality of arbitrary scan positions Yn in the sub-scanning direction is determined.
n is measured and stored in the RAM 122 (S21 to S2
6). Next, during the main scan, a similar scan position Y
n, the document surface height Hn is measured, the document surface height Hpn detected in the preliminary scan is compared with the document surface height Hn detected in the main scan, and the absolute value of the difference between the two is predetermined. If the distance is larger than the fixed value Hs, it is determined that the distance from the line sensor 11 to the document surface has greatly changed due to page turning or the like, and error detection is performed.
(S27 to S34).

As described above, in the image reading apparatus according to the first embodiment, since the reading surface is set upward, the book document cannot be pressed from above with a document pressing plate or the like, and the document surface is easily moved. However, during scanning (preliminary scan and main scan), monitor the change in the document surface height, or monitor the change in document surface height between the preliminary scan and the main scan. Because
If the page is turned while reading the image of the book document, it is surely detected that the page is abnormal. Therefore, it is possible to prevent the occurrence of problems such as deviation, distortion, and love of the read image due to the document being turned while the document surface is being scanned. Further, since the line sensor 11 for reading the document surface also serves as a means for measuring the height of the document surface, the above-described problem can be prevented with a simple configuration. Moreover, when an abnormality is detected, a predetermined warning is displayed on the operation panel 1, so that
The operator can easily recognize the contents of the items to be processed, and the convenience for the operator is improved.

<< Embodiment 2 >> Embodiment 1 described above
Is used to detect a change in the distance from the line sensor 11 to the document surface, by detecting the distance between the line sensor 11 and the document surface. In order to measure the distance from the line sensor 11 to the document surface, It is also possible to use a simple distance sensor generally used.
The second embodiment differs from the first embodiment in that such a distance sensor is used. Further, Embodiment 2
The image reading apparatus according to (1) also detects the page turning direction of the book document, and when outputting the read image data to a printer or the like, the page order of the output image can be aligned with the page order of the document.

FIGS. 14A and 14B are schematic configuration diagrams showing the image reading apparatus according to the second embodiment as viewed from the front and side, respectively. As shown in FIG. 14A, the reading unit 2 of the image reading apparatus according to the second embodiment has a plurality of distance measuring means for measuring a distance to a fixed point set on the document surface. A distance measuring section 40 including sensors (from the left, distance measuring sensors SE1 to SE4) is incorporated. Each of the distance measuring sensors SE1 to SE4 is fixed to the distance measuring unit 40. As shown in FIG. 3B, the distance measuring section 40 is formed on the document table 7 to prevent erroneous detection due to the movement of the operator's hand and to enable distance measurement even for a small-sized document. It is arranged to measure the distance to the document surface at the back side position in the work space. Each ranging sensor SE1-SE
The distance between the line sensor 11 and the line sensor 11 is a known dimension, and the distance from the line sensor 11 to the document surface can be determined by measuring the distance to the document surface with the distance measuring sensors SE1 to SE4.

FIG. 15 is a block diagram showing the overall configuration of the control unit of the image reading apparatus according to the second embodiment.
Signals from various operation keys on the operation panel 1 and detection signals from the distance measurement sensors SE1 to SE4 are input to U101. Otherwise, the configuration is the same as that shown in FIGS. 9 and 10, and a description thereof will be omitted. Also in the second embodiment, the control unit 100 corresponds to a distance change detecting unit and an abnormality detecting unit.

FIG. 16 shows four distance measuring sensors SE1 to SE.
9 is a flowchart illustrating a procedure for detecting a change in the height of the document surface according to the second embodiment including the first embodiment.

Each of the distance measuring sensors SE1 to SE4 is
As shown in FIG. 14A, the distance to a fixed point set on the document surface is detected. When the fixed distance measuring sensors SE1 to SE4 are used, the distance can be measured at an arbitrary timing even when the line sensor 11 is not scanning. In the illustrated example, when the preliminary scan is started (S41), the distance to the document surface is measured by each of the distance measurement sensors SE1 to SE4 (S42) and stored in the RAM 122.

Next, the timer starts after the timer is initialized (S43), and after a lapse of a predetermined time Ts (S44 "Y").
es "), the distance to the document surface is determined by each of the distance measurement sensors SE1 to SE.
The measurement is performed again by E4 (S45) and stored in the RAM 122. The CPU 102 compares the current measured value with the immediately preceding measured value, and when the difference between the two measured values greatly changes beyond a preset value (S46 “Y”).
es "), the page sensor, etc.
The CPU 101 detects an error assuming that the distance from the document to the document surface has greatly changed, notifies the CPU 101 to stop the operation of each unit, and displays error information and a re-reading method (S47). If there is no change in distance (S46 "N
o "), it is determined whether or not the main scan has been completed (S)
9).

Until the main scan is completed (S48)
“Yes”, S49), and repeats the processing of steps S43 to S48. That is, the distance to the document surface is measured by each of the distance measurement sensors SE1 to SE4 for each unit time Ts (S4
If there is a change in the distance measurement value, an error is detected and notified to the CPU 101 (S46 "Ye").
s ", S47).

<< Detection of Page Turning Direction of Document >> FIG.
9 is a flowchart showing a procedure for detecting a page turning direction of a document using four distance measuring sensors SE1 to SE4. Here, the distance measuring sensors SE1 to SE4 are shown in FIG.
As shown in (A), the points on the document surface are arranged so as to be measured from the left side as viewed from the sensor SE1.

As shown in FIG. 17, when the page turning direction detection routine starts (S51), first, sensor change flags corresponding to the respective distance measuring sensors SE1 to SE4 are initialized (S52). Each ranging sensor SE1-SE
4 to measure the distance to the document surface (S53).
122.

Next, the timer is started after being initialized (S54), and after a lapse of a predetermined time Ts (S55 "Y").
es "), the distance to the document surface is determined by each of the distance measurement sensors SE1 to SE.
The measurement is performed again by E4 (S56) and stored in the RAM 122. The CPU 102 compares the current measured value with the immediately preceding measured value, and determines that the difference between the two measured values is smaller than a preset value and there is no change in distance (S57 “N”).
o "), and there is no new scan request (S5).
8 "No"), the distance measurement is repeated at intervals of the predetermined time Ts (S54 to S58). If there is a scan request (S5
8 "Yes"), and detects "no page turning" (S
59).

On the other hand, when it is determined that there is a change in the distance measured by the distance measuring sensors SE1 to SE4 (S57 "Ye
s "), the distance measuring sensors SE1 to S whose measurement distances have changed.
The sensor change flag corresponding to E4 is set to 1 (S6
0 to S67), distance measurement is repeated at intervals of a predetermined time Ts.

Referring to FIG. 14A, in the case of "left page turning", first, distance measuring sensors SE4 and SE3 are used.
Greatly changes, and when the right page is turned to the left, the measurement distance of the distance measuring sensor SE2 greatly changes,
Finally, the measurement distance of the distance measurement sensor SE1 changes greatly. Conversely, in the case of "right page turning", first, the measurement distances of the distance measurement sensors SE1 and SE2 greatly change,
When the left page is turned to the right, the measurement distance of the distance measurement sensor SE3 changes greatly, and finally, the measurement distance of the distance measurement sensor SE4 changes greatly.

Focusing on the set state of the sensor change flag, in the case of "left page turning", first, flag 1 is set to 1 (S62 "Yes", S63), and 1 is subsequently set to flag 3 in order. Set (S66 "Yes", S
67), and 1 is set to the flag 2 (S64 "Ye").
s ", S65), and finally, 1 is set to the flag 1 (S60" Yes ", S61). Conversely, in the case of “turn right page”, first, 1 is set to flag 1 (S
60 “Yes”, S61), and thereafter, 1 is set to the flag 2 (S64 “Yes”, S65), 1 is set to the flag 3 (S66 “Yes”, S67), and finally, 1 is set to the flag 4 Is set (S62).
"Yes", S63).

Therefore, when the measurement distance of the distance measuring sensor SE1 changes and 1 is set in the flag 1, (S
60 "Yes", S61), if 1 has already been set to all of the flags 2 to 4 (S68 "Yes"), "left page turning" is detected (S69). When the measurement distance of the distance measuring sensor SE4 changes and the flag 4 is set to 1 (“Yes” in S62, S63), the flag 1 is set.
If 1 has already been set to all of 3 (S70 “Y
es "), and" turn right page "is detected (S71).

<< Detection of Document Reading Order >> FIG. 18 is a flowchart showing a procedure for detecting a document reading order when a plurality of pages of a document are continuously read. As shown in FIG. 18, when the document reading order detection routine starts (S81), first, a last page flag is initialized (S82), and it is determined whether or not the input from the operation panel 1 is a double-page scan. A judgment is made (S83). If a double-page spread has been input (S83 “Yes”), double-page spread
The image is read using the pages as one document (S8).
4).

When the left and right pages that have been opened are divided and read (S83 "No"), it is determined whether the input from the operation panel 1 is a "left-bound document" or a "right-bound document". (S85).

The input from the operation panel 1 is “left bound original”
And if the last page flag is 0 (S8
5 "Left", S86 "No"), the left and right pages are divided and read in the order of the left page and the right page in the state shown in FIG. 14A (S87, S88). If it is “left-bound document” and the last page flag is 1 (S85)
“Left”, S86 “Yes”), right and left pages are read in order in the order of the right page and the left page (S90, S91).

On the other hand, if the input from the operation panel 1 is "right-bound document" and the last page flag is 0 (S85 "right", S89 "No"), the right and left pages are turned in the order of right page and left page. (S90, S9)
1). If it is "right-bound document" and the last page flag is 1 (S85 "right", S89 "Ye
s "), the left and right pages are divided and read in the order of the left page and the right page (S92, S93).

When the reading of the facing pages or the divisional reading of the right and left pages is completed, the direction in which the document pages are turned by the operator is detected (S94). The page turning direction detection routine is as shown in FIG.

When the page turning direction is detected, it is determined whether or not the binding direction of the document set in advance from the operation panel 1 matches the detected page turning direction (S9).
5). If the binding direction of the document and the page turning direction match (S95 "Yes"), as in the case of "left binding document" and "left page turning", for example, the reading of the document is performed on the first page of the document. , It is detected that “first page reading” has been performed (S9).
6).

On the other hand, when the binding direction of the document and the page turning direction do not match (S95 "No"), if the spread reading mode is set (S97 "Yes"), the document is read from the last page of the document. Because
"Last page read" is detected (S9).
9). In the split reading mode (S97 "No"),
If the last page flag is 1, it is detected that "last page is read"("Yes" in S98, S9
9) If the last page flag is 0, the last page flag is set to 1 and a restart instruction is displayed on the operation panel 1 to wait for start (S98 "No", S10)
0, S101). If there is a start request, step S8
The processing from step 5 is repeated.

According to the second embodiment, as in the first embodiment, since the change in the document surface height is monitored during the preliminary scan, the pages are turned while reading the image of the book document. In such a case, an abnormality is reliably detected. Therefore, the read image may be displaced or distorted due to the document being turned while scanning the document surface.
It is possible to prevent the occurrence of troubles such as falling in love. Further, distance measuring sensors SE1 to SE4 for measuring the distance to the document surface are provided independently of the line sensor 11, but these distance measuring sensors SE1 to SE4 are simple distance sensors generally used. As a result, the configuration of the image reading apparatus is not complicated, and an increase in cost can be suppressed. In addition, when an abnormality is detected, a predetermined warning is displayed on the operation panel 1, so that the operator can easily recognize the contents of the items to be processed, and the convenience of the operator is improved.

Further, according to the second embodiment, when reading the left and right pages of a book original continuously over a plurality of pages, the original is read based on the preset original binding direction and the detected page turning direction. By detecting the order, the page order of the read image can be matched with the page order of the document.

The page order of the read image is the same as the page order of the document (ascending order) or the reverse order (descending order).
Can be determined. For this reason, by adding the page order information (first page information or last page information) to the image data and sending it to a printer or the like that outputs the read image data to recording paper, the printer side sends the page order information to the printer. Change the page order of the read image based on (for example, sort descending order to ascending order)
By switching between face-up discharge and face-down discharge, it is possible to obtain output images arranged in the same page order as the document.

FIG. 19 shows the operation of the second embodiment.
This will be described with reference to (A) to (D). FIG. 19 (A)
FIG. 7 is a conceptual diagram showing an order of reading left and right pages of a book document and a page order of an output image in the case of “left binding document, left page turning”. Similarly, FIG. 17B shows the case of “left binding original, right page turning”, and FIG.
FIG. 4D is a conceptual diagram illustrating a case of “right-binding document and left page turning” in the case of “right binding document and right page turning”, respectively. In each of the drawings, the original is conceptually shown in two upper and lower tiers, and the state after turning one page in a predetermined direction from the state of the original shown in the upper tier is shown in the lower tier.
The number attached to the manuscript indicates a page. Further, the order in which the left and right pages are read is indicated by arrows. The output images are output in order from the left side to the right side, and the numbers attached to the output images represent the pages of the corresponding read images.

As shown in FIG. 19A, in the case of "left binding original, left page turning", reading is performed in the order of left page → right page (steps S85 to S88). Also,
First page reading, which is information on page arrangement, is detected (S96). When reading image data is output, first page information is also added and output, and the printer arranges the pages in the same page order (ascending order) as the page order of the document. Get the output image. In such a case, for example, face-down discharge may be performed in the printer.

As shown in FIG. 19B, in the case of "left bound original, right page turning", the pages are read in the order of right page → left page (steps S85, S86, S90,
S91). Further, the reading of the last page, which is the information of the page arrangement, is detected (S99). When the read image data is output, the last page information is added and output. In the printer, the page order reverse to the page order of the document (descending order) To get the output images lined up with. In such a case, if the printer performs face-up ejection, for example, the pages of the output image are arranged in ascending order.

As shown in FIG. 19C, in the case of "right binding original, right page turning", the pages are read in the order of right page → left page (steps S85, S89 to S9).
1). Further, first page reading is detected (S9).
6) When outputting read image data, first page information is also added and output, and the printer obtains output images arranged in the same page order (ascending order) as the page order of the document. In such a case, for example, face-down discharge may be performed in the printer.

As shown in FIG. 19D, in the case of "right binding original, left page turning", reading is performed in the order of left page → right page (steps S85, S89, S92,
S93). Also, the reading of the last page is detected (S9).
9) When the read image data is output, the last page information is also added and output, and the printer obtains output images arranged in a page order (descending order) opposite to the page order of the document. In such a case, if the printer performs face-up ejection, for example, the pages of the output image are arranged in ascending order.

<< Embodiment 3 >> FIG. 20 shows Embodiment 3 of the present invention.
9 is a flowchart showing a procedure for detecting a document reading order when a plurality of pages of the document are continuously read.
In the second embodiment, the document reading order is detected based on the preset document binding direction and the detected page turning direction. However, in the third embodiment, the predetermined page alignment is determined. Embodiment 2 is different from Embodiment 2 in that the document reading order is detected based on information (first page reading or last page reading) and the detected page turning direction.

As shown in FIG. 20, when the original reading order detecting routine starts (S111), first, the right binding flag is initialized (S112), and then the input from the operation panel 1 is a double-page scan. Is determined (S
113). If a double-page spread is input (S11
3 "Yes"), and an image is read using two facing pages as one document (S114).

In the case of divided reading (S113 "N
o)), it is determined whether the input from the operation panel 1 is "first page reading" or "last page reading" (S115).

If the input from the operation panel 1 is "read first page" and the right binding flag is 0 (S115 "first page", S116 "N
o "), the left and right pages are divided and read in the order of the left page and the right page (S117, S118). If it is “first page reading” and the right binding flag is 1 (S115 “first page”, S116 “Ye
s "), right and left pages are divided and read in this order (S120, S121).

On the other hand, if the input from the operation panel 1 is “read last page” and the right binding flag is 0 (S115 “last page”, S119 “No”),
The left and right pages are divided and read in the order of the right page and the left page (S120, S121). If it is "Last page read" and the right binding flag is 1 (S11
5 "Last page", S119 "Yes"), the left and right pages are divided and read in the order of the left page and the right page (S
122, S123).

When the reading of the facing pages or the divisional reading of the right and left pages is completed, the direction in which the document pages are turned by the operator is detected (S124). The page turning direction detection routine is as shown in FIG.

When the page turning direction is detected, a preset “first page reading” is performed from the operation panel 1.
Alternatively, a combination of "last page reading" and the detected page turning direction is determined (S125). In the case of "left page turning" in "first page reading" or in the case of "right page turning" in combination of "last page reading" (S125 "Yes"), the document to be read is "left bound document". Is detected (S126).

On the other hand, if the "first page reading" is "right page turning" or the "last page reading" is a combination of "left page turning" (S125 "No"), if the spread reading mode is selected. (S127 "Yes"), it is detected that the document to be read is a "right-bound document" (S129). If it is the divided reading mode (S127 “No”) and the right binding flag is 1, it is detected that the document is a “right binding document” (S128 “Yes”, S129), and the right binding flag is set to 0.
If so, the right binding flag is set to 1 and a restart instruction is displayed on the operation panel 1 to wait for a start (S12).
8 “No”, S130, S131). If there is a start request, the processing from step S115 is repeated.

According to the third embodiment, when reading the left and right pages of a book original continuously over a plurality of pages, information of a preset page arrangement (first page reading or last page reading) is detected. By detecting the document reading order based on the page turning direction described above, the page order of the read image can be made the same as the page order of the document, as in the second embodiment.

The page order of the read image is the same as the page order of the document (ascending order) or the reverse order (descending order).
As in the second embodiment, by adding page order information (first page information or last page information) to image data and sending it to a printer or the like, the printer It is possible to obtain output images arranged in the same page order as the page order.

FIG. 21 shows the operation of the third embodiment.
This will be described with reference to (A) to (D). FIG. 21 (A)
FIG. 7 is a conceptual diagram showing an order of reading left and right pages of a book document and a page order of an output image in a case where a reading target is a left-bound book document and “first page reading, left page turning” is performed. Similarly, FIG. 10B shows a case where the object to be read is a left-bound book original and “reading the last page, right page turning”, and FIG. In the case of "page reading, right page turning", FIG. 3D is a conceptual diagram showing a case where the object to be read is a right binding book document and "last page reading, left page turning". The representation of each figure is the same as that of FIG.

Whether the original to be read is a "left-bound original" or a "right-bound original" is determined by a preset "first page read" or "last page read".
And the detected page turning direction (S125, S126, S129).

As shown in FIG. 21A, in the case of a left-bound book original, "first page reading, left page turning", the pages are read in the order of left page → right page (steps S115 to S118). . In addition, when the read image data is output, first page information, which is information of page arrangement, is also added and output, and the printer obtains output images arranged in the same page order (ascending order) as the document order. In such a case, for example, face-down discharge may be performed in the printer.

As shown in FIG. 21 (B), a left-bound book document which is “read last page, turn right page”
Is read in the order of right page → left page (steps S115, S119 to S121). In addition, when the read image data is output, the last page information is also added and output, and the printer obtains output images arranged in a page order (descending order) reverse to the page order of the document. In such a case, if the printer performs face-up ejection, for example, the pages of the output image are arranged in ascending order.

As shown in FIG. 21C, in the case of a right-bound book original and "first page reading, right page turning", the pages are read in the order of right page → left page (steps S115, S116, S120). , S12
1). In addition, when the read image data is output, first page information is also added and output, and the printer obtains output images arranged in the same page order (ascending order) as the page order of the document. In such a case, for example, face-down discharge may be performed in the printer.

As shown in FIG. 21D, the right-bound book original is "Last page read, left page turn".
Is read in the order of the left page → the right page (steps S115, S119, S122, S123). In addition, when the read image data is output, the last page information is also added and output, and the printer obtains output images arranged in a page order (descending order) reverse to the page order of the document. In such a case, if the printer performs face-up ejection, for example, the pages of the output image are arranged in ascending order.

[0100]

As described above, according to the image reading apparatus of the first aspect, there are disadvantages such as displacement, distortion, and mischief of the read image due to the fact that the document is turned during scanning of the document surface. Can be prevented from occurring. Further, since the imaging means for reading the document surface also serves as a means for measuring the height of the document surface, the above-mentioned problem can be prevented with a simple configuration.

Further, according to the image reading apparatus of the present invention, it is possible to prevent the occurrence of problems such as displacement, distortion, and fall of the read image due to turning of the original while scanning the original surface. can do. Further, since it is only necessary to provide a simple distance measuring means such as a distance sensor in addition to the imaging means for reading the document surface, the configuration of the image reading apparatus is not complicated and the increase in cost can be suppressed.

According to the image reading apparatus of the third aspect, when an abnormality is detected, a predetermined warning is displayed on the display unit, so that the operator can easily recognize the contents of the items to be processed, and For the elderly.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an overall configuration of an image reading apparatus.

FIGS. 2A and 2B are schematic configuration diagrams showing a state where the image reading apparatus is viewed from the front and side, respectively.

FIG. 3 is a perspective view illustrating a configuration of a driving mechanism of a reading unit.

FIG. 4A is a diagram showing the principle of a document surface height detection process used in the present embodiment, and FIG. 4B is a diagram showing a case where a document is read in the state of FIG. 4A; FIG. 4 is a diagram showing image data of FIG.

FIG. 5 is a diagram illustrating an output example of one line in the main scanning direction read by a CCD line sensor.

FIG. 6 is a diagram illustrating a luminance histogram created from image data for one line in a certain main scanning direction of a document read by a CCD line sensor.

FIG. 7A is a diagram illustrating a distribution of a document background luminance for one page of the document, and FIG. 7B is a diagram illustrating a distribution of character frequencies in the document.

FIG. 8 is a conceptual diagram illustrating distortion correction.

FIG. 9 is a block diagram illustrating an overall configuration of a control unit of the present apparatus.

FIG. 10 is a block diagram illustrating a configuration of an image signal processing unit in FIG. 9;

FIG. 11 is a diagram for describing a procedure for detecting a change in height of the document surface;

FIG. 12 is a flowchart illustrating a procedure for detecting a change in the height of the document surface during one scan (during a preliminary scan and a main scan).

FIG. 13 is a flowchart illustrating error detection when the height of a document changes from the end of a preliminary scan to the start of a main scan.

FIGS. 14A and 14B are schematic configuration diagrams illustrating states of the image reading apparatus according to the second embodiment when viewed from the front and side, respectively.

FIG. 15 is a block diagram illustrating an overall configuration of a control unit of the image reading apparatus according to the second embodiment.

FIG. 16 is a flowchart illustrating a procedure for detecting a change in the height of the document surface according to the second embodiment including four distance measurement sensors.

FIG. 17 is a flowchart illustrating a procedure for detecting a page turning direction of a document using four distance measurement sensors.

FIG. 18 is a flowchart illustrating a procedure for detecting a document reading order when a plurality of pages of a document are continuously read.

FIG. 19A is a conceptual diagram showing an order of reading left and right pages of a book original and a page order of an output image in the case of “left binding original, left page turning”, and FIG. In the case of "left binding original, right page turning", FIG. 14C shows the case of "right binding original, right page turning".
FIG. 4D is a conceptual diagram showing the case of “right-bound document, left page turning”.

FIG. 20 is a flowchart illustrating a procedure for detecting a document reading order when reading a plurality of pages of a document continuously according to the third embodiment.

FIG. 21A shows the order of reading left and right pages of a book original when the target to be read is a left-bound book original and “first page reading, left page turning”, and the page order of the output image. FIG. 7B is a conceptual diagram showing an example in which the object to be read is a left-bound book original and “last page reading, right page turning” is shown in FIG. FIG. 4D is a conceptual diagram showing a case where the object to be read is a right-binding book document and the "last page reading and left page turning" are respectively performed for "first page reading and right page turning".

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Operation panel (display part) 2 ... Image reading part 4 ... Distance measuring mirror (mirror) 7 ... Original platen 10 ... Book original (original) 11 ... CCD line sensor (imaging means) 12 ... Imaging lens 20 ... Image signal processing Unit 23 Image processing unit 24 Image monitor memory 40 Distance measuring unit SE1 to SE4 Distance measuring sensor (distance measuring unit) 100 Control unit (distance change detecting unit, abnormality detecting unit) 101, 102 CPU

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenichi Morita 2-3-13 Azuchicho, Chuo-ku, Osaka City Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Makoto Shinfu 2-3-3 Azuchicho, Chuo-ku, Osaka City No. 13 Osaka Kokusai Building Minolta Co., Ltd. (72) Inventor Hiroshi Otsuka 2-3-1 Azuchicho, Chuo-ku, Osaka City Osaka Kokusai Building Minolta Co., Ltd.

Claims (3)

[Claims] 1. A document placed upward on a platen,
In an image reading apparatus that reads by scanning optically, a mirror disposed at an inclination on the platen, a document surface of the document placed on the platen, and a document end surface reflected on the mirror Imaging means for reading simultaneously while scanning; distance change detection means for detecting a change in the distance from the imaging means to the document surface based on data of the document end face read by the imaging means; and the document by the imaging means An image reading apparatus, comprising: abnormality detection means for detecting an abnormality based on the distance change amount detected by the distance change detection means during scanning of a surface. 2. A document placed upward on a platen,
In an image reading apparatus that reads by scanning optically, an imaging unit that reads while scanning the original surface of the original placed on the original platen, and a distance to a fixed point set on the original surface A plurality of distance measuring means for measuring; a distance change detecting means for detecting a change in a distance from the imaging means to the document surface based on respective distance data measured by the plurality of distance measuring means; An image detecting device for detecting an abnormality based on a distance change amount detected by the distance change detecting unit during scanning of the document surface. 3. The image reading apparatus according to claim 1, wherein the abnormality detecting unit displays a predetermined warning on a display unit when the abnormality is detected.