JP2001008000A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader which always accurately reads picture information on a document surface without deformation or resolution reduction regardless of the change in height of the document surface even in the case of the document like a book document which has a recess in a part, doesn't increase the cost neither is made large-sized. SOLUTION: An LED 19, which is provided besides a lamp for read of picture information and throws light onto an approximate line in the opening direction of a document 1, and a height detection circuit 22 which converts reflected light from the LED 19 to an electric signal by a CCD 7 to discriminate the height from an original platen 2 of the surface of the document 1 by this signal are provided to detect the height from the original platen 2 of the surface of the document 1 without providing an optical system for read of the picture information on the document 1 besides the LED 19, and the picture information on the surface of the document 1 can be always accurately read without deformation or resolution reduction regardless of the change of the height of the surface of the document 1.

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 suitable for an apparatus such as an image scanner and a copying machine.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 6-294999 discloses an image reading apparatus for reading image information in which a document surface to be read, such as a thick book-type document, is not all flat but has some unevenness. As described in Japanese Patent Application Laid-Open No. H11-163, there is known a device that detects a distance of a document surface using a photoelectric conversion element different from a photoelectric conversion element that reads image information. This image reading device emits a light beam from a light projecting means including a light emitting diode and a light projecting lens dedicated to distance detection separately from an optical system for reading image information onto a document surface, and collects a reflected light beam from the document surface. It has an optical system that receives light with a line sensor that performs photoelectric conversion by a lens, and detects the distance of the document surface based on a signal from this optical system.

Further, as shown in Japanese Patent Application Laid-Open No. 7-254969, the side of the document where the irregular shape is understood is copied to a mirror,
It is known to detect the distance of the document surface by reading this image. In this image reading apparatus, a document is placed upward on a document table, and a reading unit including a photoelectric conversion element for reading the document is provided at a position where the document can be read from above. Further, a mirror for positioning the document at the end within the reading range by the reading unit at the back of the platen and for copying the end shape of the document is provided, and the end shape of the document reflected on this mirror, that is, the document is 2. Description of the Related Art There has been known an apparatus which detects an image viewed from a horizontal direction by a reading unit to detect a distance of a document surface.

[0004]

However, the cost of the image reading apparatus disclosed in Japanese Patent Laid-Open No. 6-294999 is increased because an optical system different from the optical system for reading image information is required. On the other hand, JP-A-7-254
The image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 969-969 is an image reading apparatus dedicated to a book-type original for placing an original on a platen and reading the original from above.
As compared with an image reading apparatus disclosed in Japanese Patent Application Laid-Open No. 999-1999, in which a document is placed face down on a document table and a sheet-type document that reads a document from below is also used, the cost is high and the apparatus is large. In addition, there is a problem that it is difficult to mount a convenient automatic document feeder when automatically replacing a sheet-type document and reading a large number of documents.

Therefore, the present invention always corrects the image information on the original surface or improves the resolving power even in an original such as a book-type original having a partially concave and convex portion, irrespective of a change in the irregularity of the original surface. It is an object of the present invention to provide an image reading apparatus which can read without lowering and does not increase the cost and the size of the apparatus.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a document table on which a document is loaded, a first illuminating means for illuminating the document, and a second illuminating means for illuminating the document on a substantially straight line. The image reading apparatus comprises an illuminating unit, a photoelectric conversion element that converts reflected light from the original into an electric signal, and a determination unit that determines a height of the original surface from the original platen based on a signal from the photoelectric conversion element. did.

With this configuration, even in an original having a concave portion such as a book-type original, the image information on the original surface is always accurately deformed or the resolution is reduced irrespective of the change in the irregularity of the original surface. It is possible to obtain an image reading apparatus which can read without causing any increase in cost and size of the apparatus.

[0008]

According to the first aspect of the present invention, there is provided a document table on which a document is loaded, first illuminating means for illuminating the document,
Second illuminating means for illuminating the document on a substantially straight line, a photoelectric conversion element for converting reflected light from the document into an electric signal, and determining the height of the document surface from the document table based on a signal from the photoelectric conversion element A second illuminating means for irradiating the original on a substantially straight line by a second illuminating means having a wavelength distribution different from that of the first illuminating means, and changing an illuminating position according to unevenness of the original. By reading the illumination position of the original with a photoelectric conversion element and determining the height of the original surface from the platen, there is no need to add any parts other than the second illumination means, so that the cost and the size of the device become large. Without inviting
The height of the document surface from the document table can be detected.

According to a second aspect of the present invention, when the second illuminating means has a different wavelength distribution from the first illuminating means, and the first illuminating means and the second illuminating means are simultaneously illuminated. However, since the illumination position of the second illumination means can be easily determined, highly reliable height detection can be performed.

According to a third aspect of the present invention, the image length is compressed and decompressed and output in accordance with the height of the document surface from the document table determined by the determination means. By compressing and expanding the image length according to the height from the table, it is possible to correct the deformation of the image caused by the unevenness of the document surface from the document table.

According to a fourth aspect of the present invention, the focus of the image on the photoelectric conversion element is adjusted in accordance with the height of the document surface determined from the document table determined by the determining means. By adjusting the focal point in accordance with the height of the original platen from the platen, it is possible to reduce the resolving power by adjusting the focal position to the original platen even if the original platen is at a position distant from the platen. Can be read without.

According to a fifth aspect of the present invention, the determining means makes a determination based on a change in the irradiation position of the second illuminating means on the document. By using the fact that the irradiation position of the illumination on the document is different due to unevenness from the surface, the height of the document surface from the platen is detected, so there is no need to add optical components etc. Without increasing the size of the device,
The height of the document surface from the platen can be detected.

According to a sixth aspect of the present invention, the second illumination means irradiates the original surface at an angle of 30 ° to 60 °, and the second illumination means illuminates the original. By setting the angle to an angle of 30 ° to 60 ° with respect to the original surface, the amount of change in the illumination position of the second illuminating means due to unevenness of the original surface from the original table can be made appropriate, and high accuracy Height detection becomes possible.

According to a seventh aspect of the present invention, the second illuminating means is illuminated substantially linearly in the spread direction of the book-type original. Thus, the binding portion of the book-shaped document having the largest unevenness can be detected, and the image information of the binding portion of the book-shaped document having the largest unevenness can be read without lowering the deformation or the resolution.

The invention according to claim 8 is characterized in that the second illuminating means is illuminated within 30 mm vertically in the spread direction of the book-shaped original.
Since the possibility that a color image exists within 0 mm is low, the color of the same wavelength as the second lighting means and the irradiation position of the second lighting means are at the same position, so that the irradiation position of the second lighting means Since the possibility of erroneously detecting is reduced, it is possible to perform highly reliable height detection and reduce adverse effects on image information.

(Embodiment 1) FIG. 1 is a diagram showing a main configuration of an image reading apparatus according to Embodiment 1 of the present invention, FIG. 2 is a sectional view of the image reading apparatus according to Embodiment 1 of the present invention, FIG. 3 is a detailed view of a photoelectric conversion element of the image reading device according to the first embodiment of the present invention, and FIG. 4 is a diagram showing emission wavelength characteristics of a second illumination unit of the image reading device according to the first embodiment of the present invention. 5 is a diagram showing the directional characteristics of the second illumination means of the image reading device according to the first embodiment of the present invention, FIG.
FIGS. 7 and 8 are diagrams showing originals read by the image reading apparatus according to the first embodiment of the present invention.

1 and 2, reference numeral 1 denotes an original, which is an example of a book such as a book having a closed portion at the center of a book type. An original table 2 is made of, for example, a transparent contact glass. Reference numeral 2 'denotes an original contact plate, and an original contact plate 2'
The original 1 is placed on the original platen 2 by abutting the upper or lower part of the original 1 against the original 1.

Reference numeral 3 denotes a lamp as first illuminating means, which is a white light source, has a long light-emitting portion in parallel with the original 1, and illuminates the original 1 via a reflection light collector 4. Reference numeral 5 denotes a reflection mirror which reflects light reflected from one surface of the document to an imaging lens 6 described later. Reference numeral 6 denotes an image forming lens, which forms an image of reflected light from the original 1 on a three-line CCD sensor 7 described later. Reference numeral 7 denotes a three-line CCD sensor (hereinafter, referred to as a CCD) as a photoelectric conversion element, which generates a potential corresponding to the reflected light of the document 1 formed on the surface of the CCD 7.

In FIG. 3, the image forming portion of the CCD 7 is a long light receiving element 8 having sensitivity to red, green and blue, respectively.
9 and 10, and it is possible to convert color documents into image information.

Next, 11 is a lamp 3, an imaging lens 6,
A reading carriage including components such as a CCD 7 is movably supported in the direction of arrow A by the image reading apparatus main body.
Reference numeral 12 denotes a focus adjustment motor which moves the imaging lens 6 via the table 13 to adjust the focus of one document image on the CCD 7 surface. 14 is a magnification adjusting motor,
By moving the image forming lens 6 and the CCD 7 with respect to the original 1 via 5, the projection magnification of the original 1 with respect to the CCD 7 is adjusted.

Reference numeral 16 designates the reading carriage 11 as the driving belt 1
7. A carriage drive motor that scans in the direction of arrow A via a support 18 that fixes the drive belt 17 to the reading carriage 11.

Here, with respect to the original 1, the longitudinal direction which is the reading direction of the light receiving elements 8, 9 and 10 of the CCD 7 is the main scanning direction, and the scanning direction of the reading carriage 11 by the carriage drive motor 16 is the sub-scanning direction. By scanning the document 1 in the main scanning direction and the sub-scanning direction, the front side of the document 1 can be read by the CCD 7.

In FIG. 1, reference numeral 19 denotes the reading carriage 11.
And an LED as second illuminating means for illuminating the original 1 in the reading area of the CCD 7 with an angle of θ with respect to one surface of the original in the main scanning direction. LED1
Reference numeral 9 denotes a red emission wavelength distribution shown in FIG. 4, which has a high directivity shown in FIG.

An image processing circuit 20 processes the potential information from the CCD 7 to generate image information and outputs the processed image information to an image forming apparatus 21, which will be described later. Reference numeral 21 prints on paper or the like in accordance with the image information sent from the image processing circuit 20. The image forming apparatus is a printing unit of a printer or a copying machine. Reference numeral 22 denotes a height detection circuit as processing means for processing image information sent from the image processing circuit 20 and determining the height from the document table 2 to one surface of the document.
Reference numeral 3 denotes a focus adjustment motor 13, a magnification adjustment motor 14, and a carriage drive motor 1 based on information from the height detection circuit 22.
6 is a motor drive circuit 23 that drives the motor 6.

In FIGS. 6, 7 and 8, reference numeral 24 denotes the original 1.
The above character image is a general mono black image. Reference numeral 25 denotes a photograph or picture image on the document 1, which is generally a color image in many cases. Reference numerals 26, 27, and 28 denote trajectories of the LED 19 illuminated on the original 1, which are red lines on the white original 1. Further, the locus 26 by the LED 19,
Reference numerals 27 and 28 denote a relatively small image of the original 1, particularly 30 m vertically in the spread direction of the book-type original 1 having a small number of picture images 25
The LED 19 is arranged so as to be irradiated within m.

The operation of the image reading apparatus configured as described above will be described below with reference to FIGS. First, the upper or lower part of the book-type document 1 in the facing direction is abutted against the document contact plate 2 ′ and placed on the document table 2.

Next, a reading operation for detecting the height of the document 1 is performed (hereinafter referred to as "height detection mode").
However, there is no problem when the lamp 3 is a lamp having a fast light rising characteristic such as a xenon fluorescent tube. However, when the lamp 3 is a lamp having a slow rising light characteristic such as a mercury fluorescent tube, once the light is turned off, the time required for the light to rise is short. Since it is necessary to wait for a while before reading the image information (hereinafter referred to as a “reading mode”), the lamp 3 is turned on in accordance with the LED 19 even in the “height detection mode” in which the image information is not read. There is a need. FIG. 6 shows information in which the reading carriage 11 is sub-scanned in the direction of arrow A in the “height detection mode”, and the read information is imaged by the image processing circuit 20.

Next, this image information is sent to the height detecting circuit 22.
Sent to Here, the illumination of the LED 19 causes the red locus 2 on the white image at the top of the book-type original 1 in the spread direction.
6, which deviates from the position on the straight line of the trajectory 26 according to the unevenness of the document 1 like the binding portion 26 'of the document 1. This shift amount corresponds to the height of the original 1 from the platen 2, and the shift amount is processed by a numerical value conversion table in the height detection circuit 22 which is obtained in advance, so that the original The height corresponding to the sub-scanning direction can be detected.

Here, when the irradiation angle θ of the LED 19 on the document 1 is set to 60 ° or more, the trajectory 27 shown in FIG. The accuracy of height detection deteriorates. Conversely, L
When the irradiation angle θ of the ED 19 with respect to the document 1 is set to 30 ° or less, the trajectory 28 shown in FIG. 8 is obtained.

Next, when the "height detection mode" ends, the "reading mode" starts. LE in "reading mode"
D19 is turned off because it becomes unnecessary. Reading carriage 11
Is sub-scanned in the direction of arrow A, and the original 1 is sequentially read from the end. Here, if the binding section 1 ′ of the document 1 is read normally, the image is reduced in the main scanning direction and the sub-scanning direction and the image is defocused due to the curvature of the document 1. In order to correct this, the motor drive circuit controls the magnification adjusting motor 14 for the reduction of the image in the main scanning direction and the carriage drive for the reduction of the image in the sub-scanning direction according to the information from the height detection circuit 22. The drive speed of the motor 16 is set lower than the normal reading speed, and the defocus of an image is handled by controlling the focus adjustment motor 13. By controlling the motors described above, it is possible to always accurately read the image information on the original 1 surface without deforming or reducing the resolving power irrespective of the unevenness of the original 1 surface.

As described above, in the first embodiment, the original 1
In addition to the lamp 3 for illuminating the original 1 in order to read the image information of the original 1, an LED 19 for irradiating the book-type original 1 with a spread method in a substantially straight line, and the reflected light from the LED 19 is applied to the original 1.
Is converted into an electric signal by the CCD 7 for reading the image information of the original, and a height detecting circuit 22 for judging the height of the original 1 from the original table 2 based on the signal is provided.
The height of the original 1 from the platen 2 can be detected without providing an optical system for reading the image information of the original 1, so that the concave and convex portions of the original 1 can be detected. Even in the original 1 having a portion, it is possible to always accurately read the image information on the original 1 surface without deforming or lowering the resolving power irrespective of the unevenness of the original 1 surface, thereby increasing the cost,
An image reading device that does not cause an increase in the size of the device can be obtained.

Further, the wavelength distribution of the LED 19 is different from that of the lamp 3, and the LED 19
Irradiation is performed at an angle of 0 ° to 60 °. With this configuration, the height of one document surface can be detected with high probability.

(Embodiment 2) FIG. 9 is a diagram showing a main structure of an image reading apparatus according to Embodiment 2 of the present invention, and FIG. 10 is a sectional view of the image reading apparatus according to Embodiment 2 of the present invention. is there. Here, FIGS. 1 to 8 in the first embodiment.
However, the same reference numerals are given to the same constituent members, and the detailed description is omitted.

9 and 10, the focus adjustment motor 13 and the magnification adjustment motor 14 are not provided as compared with FIGS. 1 and 2 in the first embodiment, and the information from the height detection circuit 22 is returned to the image processing circuit 20 again. It is.

The operation of the image reading apparatus configured as described above will be described below. First, in the second embodiment, the lamp 3 and the LED 19 are turned on simultaneously to read the original 1 while the “reading mode” and the “detection mode” are simultaneously performed. Detection is performed, and image information of the entire surface of the document 1 is recorded in the image processing circuit 20. Here, the binding section 1 ′ of the original 1
Is reduced in the main scanning direction and the sub-scanning direction due to the curvature of the original 1. In order to correct this, reduction of the image in the main scanning direction,
The image information in the image processing circuit 20 is corrected so as to correct the reduction of the image in the sub-scanning direction.
By removing the red component due to the illumination of No. 9, it becomes possible to always accurately read the image information on the original 1 without deforming or lowering the resolving power irrespective of the unevenness of the original 1.

Here, by irradiating the LED 19 with the LED 19 within 30 mm above and below the spread direction of the original 1, the possibility that the character image 24 or the picture image 25 on the original 1 and the illuminated portion of the LED 19 overlap with each other is low. The surface height detection accuracy can be improved, and the irradiation of the LED 19 does not adversely affect image information.

As described above, in the second embodiment, the original 1
In addition to the lamp 3 for illuminating the original 1 in order to read the image information of the original 1, an LED 19 for irradiating the book-type original 1 with a spread method in a substantially straight line, and the reflected light from the LED 19 is applied to the original 1.
Is converted into an electric signal by the CCD 7 for reading the image information of the original, and a height detecting circuit 22 for judging the height of the original 1 from the original table 2 based on the signal is provided.
The height of the original 1 from the platen 2 can be detected without providing an optical system for reading the image information of the original 1, so that the concave and convex portions of the original 1 can be detected. Even in the original 1 having a portion, it is possible to always accurately read the image information on the original 1 surface without deforming or lowering the resolving power irrespective of the unevenness of the original 1 surface, thereby increasing the cost,
An image reading device that does not cause an increase in the size of the device can be obtained.

Further, the wavelength distribution of the LED 19 is different from that of the lamp 3, and the LED 19
Irradiation is performed at an angle of 0 ° to 60 °, and the LED 19 is illuminated within 30 mm above and below the spread direction of the original 1. With this configuration, the height of the original 1 can be detected with a high probability. Can also reduce adverse effects on image information.

[0039]

As described above, according to the present invention, in addition to the first illuminating means for illuminating the original in order to read the image information of the original, the book-type original spread method for illuminating the original in a substantially straight line is used. Illuminating means, and the reflected light from the second illuminating means is converted into an electric signal by a photoelectric conversion element for reading image information of the original, and the signal is used to determine the height of the original surface from the original platen. Is provided, the height of the document surface from the platen can be detected without providing an optical system for reading the image information of the document other than the illuminating means. Even in a document having a concave / convex portion, image information on the document surface can always be read accurately without deforming or reducing the resolution, regardless of changes in the surface roughness of the document, resulting in an increase in cost and size of the apparatus. A picture without things Reader is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a main configuration of an image reading apparatus according to a first embodiment of the present invention;

FIG. 2 is a sectional view of the image reading apparatus according to the first embodiment of the present invention;

FIG. 3 is a detailed view of a photoelectric conversion element of the image reading device according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating emission wavelength characteristics of a second illumination unit of the image reading apparatus according to the first embodiment of the present invention;

FIG. 5 is a diagram showing directional characteristics of a second illumination unit of the image reading device according to the first embodiment of the present invention;

FIG. 6 is a view showing a document read by the image reading apparatus according to the first embodiment of the present invention;

FIG. 7 is a view showing a document read by the image reading apparatus according to the first embodiment of the present invention;

FIG. 8 is a view showing a document read by the image reading apparatus according to the first embodiment of the present invention;

FIG. 9 is a diagram illustrating a main configuration of an image reading apparatus according to a second embodiment of the present invention;

FIG. 10 is a sectional view of an image reading apparatus according to a second embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original 2 Platen 3 Lamp 7 3-line CCD sensor (CCD) 19 LED 22 Height detection circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/107 H04N 1/10 F-term (Reference) 2H051 AA01 BA47 BB19 CC03 EB19 FA03 5B047 AA01 AA30 AB04 BA02 BB02 BC05 BC09 BC11 CA05 CA08 CB09 CB22 5C051 AA01 BA03 DA03 DB01 DB22 DB24 DB28 DC07 DE05 DE19 EA01 FA01 5C072 AA01 BA17 CA03 CA04 CA05 EA05 LA17 QA16 RA04 RA11 VA06 WA04 XA01

Claims (8)

[Claims] 1. A document table on which a document is loaded, first illuminating means for illuminating the document, second illuminating means for illuminating the document on a substantially straight line, and converting reflected light from the document into an electric signal. An image reading apparatus comprising: a photoelectric conversion element; and determination means for determining a height of a document surface from the document table based on a signal from the photoelectric conversion element. 2. An image reading apparatus according to claim 1, wherein said second illumination means has a different wavelength distribution from said first illumination means. 3. The image reading apparatus according to claim 1, wherein an image length is compressed and expanded and output in accordance with a height of the document surface determined from said document table determined by said determination means. apparatus. 4. The image reading apparatus according to claim 1, wherein a focus of the image on the photoelectric conversion element is adjusted in accordance with a height of the document surface determined from the document table determined by the determination unit. apparatus. 5. An image reading apparatus according to claim 3, wherein said determination means makes a determination based on a change in an irradiation position of the second illumination means on the document. 6. The apparatus according to claim 1, wherein the second illuminating means is provided on the surface of the original document.
6. The image reading device according to claim 5, wherein the light is emitted at an angle of from 60 to 60 degrees. 7. An image reading apparatus according to claim 6, wherein said second illuminating means irradiates the book-type original in a spread direction substantially in a straight line. 8. An image reading apparatus according to claim 7, wherein said second illuminating means irradiates the book-type document within 30 mm vertically in the spread direction.