JP2002247314A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image reader for reading out an article to be read out, e.g. a document, from above in which the height of the document can be detected accurately regardless of such conditions as the density or gloss of the document and without increasing the power of a light source for detecting the height of the document significantly. SOLUTION: A document 15 is irradiated obliquely with a linear beam light from a light emitting section 17, boundary between an irradiated part and other part on the light receiving plane 16 is read out from the luminance data thereof and then the height of the document 15 is detected therefrom. Since a part irradiated with the beam light and a part shielded by the document edge and not irradiated with the beam light are generated, a stabilized difference of luminance can be attained and the height can be detected by detecting the boundary thereof.

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 for reading a book or other object from above and obtaining image data, and more particularly to a technique for detecting the height of an object to be read.

[0002]

2. Description of the Related Art In an upside-down type scanner (so-called book scanner) for reading an original such as a book from above, a distance measuring method for detecting the height of the original includes a mirror at the upper end surface (top) of the original. Copying and reading the image with a sensor and detecting using the difference in the luminance value between the upper end surface and the background, or detecting by detecting the degree of curvature of the upper and lower edges of the original from the read image of the original are common. Is known.

[0003] For example, see Japanese Patent Application Laid-Open No. 60-254869.
In the publication, an image sensor detects a document surface and a detection surface having a reflectance different from that of a document surface provided in other portions, and detects a main scanning of the detection surface based on a difference between the document surface luminance and the detection surface luminance. There has been proposed a method of measuring the length in the direction and detecting the height of the document.

Japanese Patent Application Laid-Open No. 61-237569 discloses a height detecting method using a spot light. The detecting means detects a luminance difference between a document surface and a spot light irradiated on the document surface. The method is adopted. Also, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 219323 discloses an apparatus in which a slit light is irradiated along a lateral direction (sub-scanning direction) of an object to be measured, and a surface height is detected based on a change in the position.

[0005]

In the distance measuring method using the above-described original upward scanner, distance measurement becomes difficult when the upper end surface (top) of the original has a high density. Further, there is a problem that the indoor light or the illumination light during the imaging is reflected on the operating person and reflected on the distance measuring mirror, and the operating environment is considerably restricted.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 60-254869 has a problem in that when reading an original having a luminance close to the luminance of the detection surface, the luminance difference becomes small and distance measurement cannot be performed accurately. Also, Japanese Patent Application Laid-Open No. 61-2375
The method disclosed in Japanese Patent Application Publication No. 69-6969 has a problem that the spot light amount (luminance value) viewed from the image sensor changes due to the influence of the density, glossiness, and the like of the document surface, and the spot light position cannot be accurately detected. Also, Japanese Patent Application Laid-Open No. 5-219323
In the method disclosed in Japanese Patent Application Laid-Open Publication No. H10-207, since linear light is irradiated in the sub-scanning direction, it is not possible to change the light output for each measurement location. Therefore, correction based on the density difference of the original is performed. Can not do.

Further, when the object is obliquely irradiated with the line light for distance measurement, the light is shielded at the end face of the object, and the light is detected by a sensor. The problem is that it is difficult to distinguish between the line light for distance measurement and the original. When irradiating high-luminance line light over the entire width of the document, it is necessary to increase the power of the laser that emits the line light for distance measurement in order to surpass the illumination for image reading. You can't get that much power for safety.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a reading apparatus for reading an object to be read from above is provided.
It is possible to accurately detect the height of the object without being affected by the state such as the density and glossiness of the object to be read and without having to increase the power of the light source for detecting the height of the object to be read. It is an object to provide a possible image reading device.

[0009]

In order to achieve the above object, the invention according to claim 1 comprises a reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read, An image reading apparatus comprising: a height detection unit that detects an irradiation position of the light beam that is changed by the height of the reading target by the light emitting unit and detects a height of the reading target. A light receiving surface for receiving the light beam emitted by the light emitting means, the height detecting means being located on an extension of the surface on which the light beam is emitted by the light emitting means on the light receiving surface other than the light emitting unit and the light emitting unit; The boundary is read from the luminance data, and the height of the object to be read is detected, and the light emitting unit irradiates a linear beam light to the light receiving surface and is shielded by the edge of the object to be read. The receiving Light beam on the surface is one which irradiates the object to be read to generate a portion not irradiated.

In the above arrangement, the object to be read is irradiated obliquely with a linear beam light from the light emitting means, and the boundary is read from the light beam irradiation part on the light receiving surface and the luminance data of the part other than the irradiation part. The height of the object to be read is detected from the position. Here, a part to be irradiated with the light beam and a part to be not irradiated with the light beam, which is shielded by the edge of the object to be read, are generated, so that a stable luminance difference can be obtained, and the boundary between them is detected. By doing so, highly accurate height detection can be performed without being affected by the state of the reading target, such as the density and glossiness. The light beam may be scanned and irradiated, and the luminance data of the irradiated portion and the other portions may be scanned and read by the sensor at the same time as the scanning of the light beam. This sensor can also be used as a sensor used as reading means for reading the object to be read. The detected height data is used for focusing of an optical system for reading, and for correcting the density and distortion of an image.

According to a second aspect of the present invention, in the image reading apparatus of the first aspect, the irradiation angle of the light beam by the light emitting means is set to an obtuse angle than the reading angle of the optical lens provided in the reading means. The height detection is performed by detecting a luminance difference between the light irradiation unit and the light shielding unit due to the object to be read. This makes it possible to reliably detect the height from the luminance difference at the end of the object to be read.

According to a third aspect of the present invention, there is provided a reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read, and an optical scanning of a sensor by the irradiation position of the light beam by the light emitting means. And a height detecting unit for detecting the height of the object to be read by detecting the irradiation position of the light beam by the sensor and discriminating the irradiation portion of the light beam from the portion other than the irradiation portion. Setting means for setting a threshold value of a brightness value for the light beam, and the width of a light beam having a brightness value equal to or greater than the threshold value set by the setting means for the light beam irradiated on the object to be read is detected by the sensor for each detection point. And a control means for changing the light beam output by the light emitting means according to the width of the light.

In the above configuration, the width of the light beam irradiated on the object to be read having a brightness value equal to or greater than the set threshold value is read by the sensor at each detection point, and the light beam of the light emitting means is read in accordance with the width. Change the output. That is, when the density of the object to be read is high, the power of the light beam is increased, and when the density is low, the power of the light beam is reduced. As a result, the difference in the width of the irradiation light beam can be suppressed, the influence of the density of the object to be read is eliminated, and the height detection accuracy can be improved.

According to a fourth aspect of the present invention, in the image reading apparatus according to the third aspect, the control means detects the next detection based on the width of the light beam having a luminance value equal to or larger than the threshold value at the plurality of detection points. A light beam output by the light emitting means at a location is determined. Thus, regardless of the density change due to the position of the reading target, the width of the light beam equal to or larger than the threshold value at many detection locations is made uniform, and the height detection accuracy can be improved.

According to a fifth aspect of the present invention, there is provided a reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read, and an optical scanning of a sensor by the irradiation position of the light beam by the light emitting means. And a height detecting means for detecting the height of the object to be read by detecting the background luminance value near the position where the light beam is irradiated by the light emitting means in the main scanning direction of the sensor. The detection is performed line by line, and the light beam output of the light emitting means is sequentially changed accordingly. Thereby, the light beam output fluctuates according to the background luminance value of the object to be read, and the height detection accuracy is improved.

According to a sixth aspect of the present invention, there is provided a reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read, and an optical scanning of a sensor by the irradiation position of the light beam by the light emitting means. And a height detecting means for detecting the height of the object to be read by detecting the height of the object to be read and the position of the light beam emitted by the light emitting means The sensor detects the irradiation diameter that changes depending on the density, and detects the height using the information. Control for changing a threshold value for obtaining the irradiation diameter of the light beam according to the density of the object to be read is performed. Means.

In this configuration, the position where the light beam is irradiated and the irradiation diameter are detected by a sensor, and the height is detected using the information. Here, the threshold value for obtaining the irradiation diameter of the light beam is changed according to the density of the object to be read.
When the density of the object to be read is high, the threshold for obtaining the irradiation diameter of the light beam is set low, and when the density is low, the threshold is set high. Thus, even when the density of the object to be read is different, it is possible to reduce an error in obtaining the beam irradiation position, and to improve the height detection accuracy.

[0018]

FIG. 1 shows the appearance of an image reading apparatus according to a first embodiment of the present invention. Image reading device (hereinafter,
The apparatus includes a scanner unit 1 that reads a document or the like to be read (an object to be read) from above and outputs the image data. The scanner unit 1 includes a line type image sensor 14 (see FIG. 2, reading means) including a CCD or the like, and an optical system including a lens for forming a document image on the image sensor. An exposure lamp unit 2 is provided above a document table 6 on which a document is placed. Light emitted from the exposure lamp unit 2 is radiated to a document placed on the document table 6 to image the image. Read by the scanner unit 1.

The present apparatus is provided with a distance measuring beam light emitting section 17 (light emitting means: see FIG. 2) for irradiating the document obliquely with a light beam to detect the height of the document. The boundary is read from the luminance difference between the part irradiated with the light beam and the part blocked, and the boundary is detected to detect the document height (details will be described later). The apparatus includes a control panel 3 for setting various modes and displaying the state, error, warning, etc. of the apparatus, a start key 8 for starting reading of a document, a power switch 9, and the like. Platen 6
The central part 7 is movable downward by pressing down,
The back of the binder etc. can be sunk.

FIG. 2 shows a detailed configuration of the optical system of the scanner unit 1 and the beam light emitting section 17 for distance measurement (hereinafter, referred to as a beam emitting section). The optical system includes a scan mirror 11, a return mirror 12, and a lens 13 that forms an original image on the image sensor 14 as a scanning mechanism. The lens 13 is driven for focusing based on the height information of the document. A light receiving surface 16 for receiving the beam light L of the beam emitting unit 17 is provided on an extension of the document table 6. The beam emitting unit 17 is made of a laser or the like. The linear beam light (L) emitted from the beam emitting unit 17 is reflected by the scan mirror 11 and is applied to the book document 15 obliquely with a certain width. This light beam (L) is scanned in the document spread direction (sub-scanning direction) by the rotation of the scan mirror 11, and the irradiation position on the light receiving surface 16 moves.

The height of the document 15 is detected based on the light beam irradiating portion on the light receiving surface 16 and the luminance data of the portion other than the irradiating portion. The beam emitting unit 17 irradiates the linear beam light to the light receiving surface 16 and simultaneously irradiates the document 15 which is shielded by the edge of the document 15 and generates a portion on the light receiving surface 16 where the beam light is not irradiated.

In the above arrangement, when the start key 8 is pressed, the linear beam light emitted from the beam emitting section 17 is reflected by the scan mirror 11 before reading of an image is started, and the original 15 and the light receiving surface are read. Irradiation is carried out in a state having a certain width obliquely to 16. Scan mirror 11
Is rotated, so that the turning mirror 12 and the lens 13
, The image of the document 15 including the irradiation light beam can be sequentially formed on the image sensor 14 in the spread direction of the document. Thus, it is possible to measure the height distribution of the document 15 and read an image of the entire surface of the document.

According to the height distribution of the document 15 obtained as described above, a part of the optical system is moved during reading, and the image is read while focusing the focus position sequentially, and based on the height detection result. First, the size and inclination of the document 15 are obtained, and image distortion correction, document outer frame erasure, and tilt correction can be performed.
The reading operation has two stages, a preliminary scan and a main scan. In the preliminary scan, the document size, the document density,
The document height and the like are detected, and based on the detected information, the area outside the document is deleted, the document density is automatically adjusted, and the focus is reflected at the time of the main scan.

FIG. 3A shows that the book document 15 is
Shows how it is installed above. In many cases, in order to prevent the pages of the book document 15 from jumping as shown in the figure, reading is performed by holding a blank portion without an image with a hand (finger) or holding it with a paperweight. When reading another page, the document pressing operation is interrupted, the page is turned, and then the book document is pressed again with the hand (finger).

FIG. 3B schematically shows the positional relationship between the distance measuring beam light irradiation position (L1) and the original reading line (L2). As shown in the figure, at the time of the preliminary scan, the light beam emitted at a fixed length on the image reading line (L2) is applied to the document surface 6 and the light receiving surface 16, respectively. In this state, the original moves in the sub-scanning direction (the direction indicated by the arrow S), and the height of the document is detected from the irradiation position of the light beam irradiated on the light receiving surface 16.

FIG. 4 shows a control circuit block of the present apparatus.
Here, a circuit for a monochrome circuit is shown. CP
U21 controls the entire circuit. CPU 21 is RAM2
While using ROM 2 as a work area for data control,
It operates in accordance with the control program stored on 23.
The CPU 21 has a function of setting an operation mode of the image processing circuit, and drives the scanning mechanism 30 including the scan mirror 11 and performs reading scanning in the sub-scanning direction.
An image sensor 14 such as a CCD converts light data of an image into a voltage. The image signal that has been photoelectrically converted is converted into digital image data by the A / D converter 24. The converted digital image data is sent to an image processing circuit (group 1) 25, where it undergoes image processing such as reflectance-density conversion, shading correction, and illuminance correction. The processed data is sent to the document height, size, and inclination detection / correction circuit 26. At the time of the main scan, the data subjected to the edge enhancement processing is transferred to the subsequent image processing circuit (group 2) 2
The image data is sent to the image output unit 28 after being subjected to enlargement / reduction, density correction and binarization processing.

FIG. 5 shows a reading operation procedure for detecting the height of the original in this apparatus. When the operator instructs the start of the reading operation, # 1: the exposure lamp unit 2 of the apparatus is turned on, and the original 1
Light 5 # 2: The beam emission unit 17 is driven to irradiate the area including the upper surface of the document 15 with the beam light for distance measurement. # 3: A preliminary scan operation is started. # 4: While driving the scanning mechanism 30, the distance measuring beam light and the lens 13 of the image reading optical system are moved, and the image sensor 14 is adjusted while substantially focusing on the document surface.
To read one line of image data. # 5: The CPU 2 outputs image data including the position data of the light beam detected for each line (for thinning, for each of a plurality of lines).
Take in 1. # 6: Transfer of read data and position data is repeated until the final read line is reached. # 7: When the reading of the entire area of the document table 6 is completed, the preliminary scan is completed. # 8: The irradiation position data of the light beam obtained by the preliminary scan is compared with the data of the reference position, the height of the document is obtained, and the size of the document is determined. # 9: In preparation for the main scan, the CPU 21 analyzes the obtained height data, corrects noise due to shading of the image, etc. from the preceding and following height data, and obtains reliable height data. # 10: The main scan operation is started. # 11: While driving the scanning mechanism 30 of the optical system to focus on the document in accordance with the height data,
Read line by line. # 12: Repeat scanning and reading until reading of the document area is completed. # 13: When the reading is completed, the main scan ends. # 14: Turn off the illumination of the exposure lamp unit 2 of the apparatus,
A series of reading operations is completed.

FIG. 6 shows an example of light beam irradiation. In this example, a point P which is an edge on the document 15 is
In the case of reading at 4, the read image is reduced by the lens 13 and is read at the Q pixel portion of the image sensor 14, and the reading angle is the angle α. The angle of the beam light (L) emitted from the beam emitting unit 17 is α
By setting the angle β to be larger, the linear beam light is transmitted from point T on the upper surface of the document 15 to point P and from point R on the light receiving surface 16 that is not shielded by the document 15 as indicated by the thick line in the drawing. The light is radiated to the point and becomes a high-luminance part. When the image sensor 14 reads the point R in the figure, the reading angle is α
This results in a larger γ angle. The range of γ minus α is
This is a low-luminance portion that is shielded by the original 15 and is not irradiated with the light beam on the light receiving surface 16. The point R (corresponding to the point P, which is the edge of the document) can be detected by the image sensor 14 from the luminance difference between these parts. The point W is a reference position where the end of the document 15 on the document table is placed, and is also a boundary with the light receiving surface 16.

FIG. 7 shows the relationship between the document density and the luminance value between the above points. Note that the length between the points on the horizontal axis changes according to the document height. During the period from T to P, the surface of the document 15 is irradiated with the light beam, and the luminance value changes depending on the density of the document 15. The light beam is shielded by the document 15 between PR and R, and the light value is low because the light beam does not hit the light receiving surface 16, and the brightness value is high between R and S which are not shielded. By detecting a luminance value with the image sensor 14 and detecting a boundary between the luminance values of the PR and RS portions, as described below,
Document height data is obtained.

FIG. 8 shows the main scanning direction 1 when the height of the original 15 is high, when it is low, and when there is no thickness like a sheet original.
4 shows an example of a read image of a line. Manuscript 15 between UP
, The portion of the document 15 irradiated with the light beam between the points T-P, the portion (1) of the light receiving surface 16 not irradiated with the light beam between the points PR, R-S The interval (2) is the portion of the light receiving surface 16 where the light beam is irradiated, and the point W indicates the pixel position (reference) stored in the image sensor 14 at the document side end of the light receiving surface 16. Between W and S, the entire light receiving surface 16 is shown.

If there is no original 15, the beam emitting unit 17
The irradiated linear beam light is irradiated only between WS and there is no portion having a low luminance value in the light receiving surface 16, and at this time, the height of the document 15 is recognized as 0 mm. Thus, it is possible to cope with an original having a small thickness such as a sheet original. If there is a document, the length of the above-mentioned portions (1) and (2) of the document surface irradiated with the light beam and the light receiving surface 16 changes depending on the height of the document 15, but the area covered by the document 15 There is a light receiving surface (1), and a constant luminance value can be input to the image sensor 14 for this portion. Therefore, it is possible to obtain a stable luminance difference between the light beam irradiation unit and the shielding unit, and it is possible to accurately detect the height of the document 15 by reading the position where the luminance difference exists. If the height is detected by an appropriate combination of the point R and the points T and P, more accurate document height data can be obtained.

As described above, according to the present embodiment, it is not necessary to increase the power of the light source for detecting the height of the original document without being affected by the density and glossiness of the original document. Thus, the height of the document can be accurately detected.

Next, an image reading apparatus according to a second embodiment of the present invention will be described with reference to FIGS.
The appearance of this device is the same as the first embodiment shown in FIG. 1 described above. FIG. 9 shows the configuration of the optical system of the present apparatus. The distance measuring beam light emitting section 31 (light emitting means) is different from that of the first embodiment and emits a point-like beam light B. The scanning mechanism is the same as described above. FIG. 10 schematically shows the positional relationship between the distance measuring beam light irradiation position (B1) and the original reading line (L2). As shown in the drawing, at the time of the preliminary scan, the distance measuring beam light is irradiated on the image reading line (L2), and the beam is scanned in the sub-scanning direction (the direction shown by the arrow S) in that state, and the irradiation position of the light beam is changed. The height of the document is detected by reading with the image sensor 14.

FIG. 11 shows a control circuit block of the present apparatus. The third embodiment is the same as the first embodiment except that the distance measuring beam light emitting section 31 is different. As described below, the CPU 21 has a function of controlling the output of the light beam of the light metering beam light emitting unit 31 (control means).

FIGS. 12 and 13 show a reading operation procedure for detecting the height of the original in this apparatus. Steps equivalent to those in FIG. 5 are given the same step numbers. When the operator instructs the start of the reading operation, # 1: the exposure lamp unit 2 of the apparatus is turned on, and the original 1
Light 5 # 3: A preliminary scan operation is started. # 3-1: A part of the optical system is moved so that the distance measuring beam light is almost condensed on the original, and the distance measuring beam light emitting unit 31 is moved.
Is operated to irradiate the original 15 with a light beam. # 4: While driving the scanning mechanism 30, the distance measuring beam light and the lens 13 of the image reading optical system are moved, and the image sensor 14 is adjusted while substantially focusing on the document surface.
To read one line of image data. # 5: The position and length (width of light beam) of a pixel having a brightness value higher than a preset threshold value is obtained from the brightness value data for each line (in the case of thinning, for each of a plurality of lines) (pixel column count). Take in. The threshold value set in advance may be, for example, a threshold value optimal for the distance measurement of the document table 6 or a threshold value set based on the maximum value of the assumed density of the reading object. # 5-1 to # 5-6: If the length (count number) is longer or shorter than a preset reference length, the CPU 21
The power of the distance measuring light beam is reduced or increased in consideration of the difference from the reference length. The preset reference length is 3 to 5
Make it about a pixel. # 6: Transferring the read data and the position / length data and changing the intensity of the ranging light beam are repeated until the final read line is reached. # 7: When the reading of the entire area of the document table 6 is completed, the preliminary scan is completed. # 8: The irradiation position data of the light beam obtained in the preliminary scan is compared with the data at the reference position to determine the height of the document. # 9: In preparation for the main scan, the CPU 21 analyzes the obtained height data, corrects noise due to shading of the image, etc. from the preceding and following height data, and obtains reliable height data. # 10: The main scan operation is started. The subsequent processes up to # 14 are the same as those in FIG.

In the above, the background luminance value in the vicinity of the position where the light beam is irradiated by the light emitting section 31 is determined by the image sensor 1.
4 may be detected for each line in the main scanning direction, and the light beam output of the light emitting unit 31 may be sequentially changed accordingly.

FIGS. 14A and 14B show images at the light beam passage positions when the read original is white and black, respectively. In the case of a white original, the position through which the light beam has passed has a high luminance value over a wide range. As the number of pixels exceeding the threshold value increases over a wider range, the error in obtaining the median value increases. Therefore, it is necessary to take measures such as increasing the threshold value. On the other hand, in a black document, although there are high luminance portions, there are lines where only luminance lower than the threshold is obtained, which may result in erroneous detection. Note that, in the figure, the horizontal line is the main scanning direction.

In the above embodiment, the width of the light beam irradiated on the object to be read having a luminance value equal to or greater than the set threshold value is read for each detection point, and the light beam output is changed according to the width. The difference in beam width can be suppressed, eliminating the influence of the density of the object to be read,
Height detection accuracy is improved.

Next, an image reading apparatus according to a modification of the second embodiment will be described with reference to FIGS. The optical system of this apparatus, the configuration of light beam irradiation, and the control circuit block are the same as those of the above-described second embodiment shown in FIGS. 9, 10, and 11, and therefore description thereof is omitted. This device is similar to the second embodiment in that the distance measuring beam light emitting unit 3 is used.
1 is used.

FIGS. 15 and 16 show a reading operation procedure for detecting the document height in the present apparatus. Steps equivalent to those in FIG. 5 or FIG. 12 are given the same step numbers. When the reading operation start is instructed by the operator, steps # 1 to # 7 are the same as the steps of the same number described above. # 8: The irradiation position address of the light beam obtained in the preliminary scan is stored in the memory in advance as 0, 10, 20
The height of the object to be read is determined by comparing with a position address corresponding to some reference height such as mm (for details, see FIG. 18 described later). Details of this step are shown in FIG. # 9
# 14 are equivalent to the above.

FIG. 16 shows a procedure for obtaining the height of the object to be read. # 81: One line data of the object to be read obtained by the preliminary scan is read by the CPU 21. # 82: It is determined whether or not the luminance value of the pixel of the portion where the light beam has passed in the 1-line data is the maximum (255 in the case of 8 bits). # 83: If there is no pixel (light beam) having the maximum luminance value,
The threshold for calculating the irradiation diameter of the light beam is reduced by about 1/10 of the maximum luminance value (255 for 8 bits). That is, the CPU 21 (control means) changes the threshold value when calculating the irradiation diameter of the light beam according to the density of the object to be read. # 84: After lowering the threshold, searching is performed until a pixel having a luminance value larger than the threshold is found. By changing the threshold value for each line, it is possible to reduce an error in finding the center of a point through which the beam has passed (hereinafter, referred to as a center point). # 85: Count the number of consecutive pixels whose luminance value is equal to or larger than the threshold value. # 86: The position address of the center point of the continuous number of pixels (pixels through which the light beam has passed) obtained in # 85 is obtained. The position address can be obtained by adding a value of half of the count number to the position address at which counting is started. # 87: The height of the object to be read is determined by comparing the position address of the center point with position addresses corresponding to some reference heights such as 0, 10, 20 mm, etc., which are stored in the memory in advance.

The method for determining the height of the object to be read in # 87 will be described with reference to FIG. FIG. 17 is a side view of the apparatus, and shows a state in which the original 15 is irradiated with the light beam B from the light beam emitting unit 31 for distance measurement. In the drawing, reference numeral 41 denotes a light beam irradiation position when the document height is 30 mm, reference numeral 42 denotes a beam light irradiation position when the document height is 0 mm, reference numeral 43 denotes a beam light irradiation position on the object to be read, and reference numeral 51 denotes a document height 30 mm. 1 line data at the time, 52
Is one line data when the document height is 0 mm, and 53 is one line data of the reading target. Here, the irradiation position (4) of the light beam corresponding to the previously calculated reference document height is set.
1, 42) (reference position address)
The light beam address (irradiation position address) for the object to be read is calculated. For example, if the address at a height of 0 mm is 6000 and the address at a height of 30 mm is 5000, and if the irradiation position address of the center point of the light beam passing through the reading object is 5500, the height of the reading object is Fifteen
mm.

In the above embodiment, the threshold value for calculating the beam diameter of the light beam is changed in accordance with the density of the object to be read. And height detection accuracy can be improved.

[0044]

As described above, according to the present invention, when the object to be read is irradiated with the linear beam light obliquely, the light beam is shielded by the portion irradiated with the beam light and the edge of the object to be read. A part that is not irradiated with the light beam is generated, the boundary is read from the luminance data of the irradiated part and the part other than the irradiated part, and the height of the object to be read is detected based on the boundary. A stable luminance difference can be obtained without being affected by the state such as the density and glossiness of the object, and the height of the object to be read can be accurately detected.

Further, a simple configuration in which the width of the light beam irradiated on the object to be read having a luminance value equal to or greater than the set threshold value is read for each detection point, and the light beam output is changed according to the width. However, the difference in the width of the irradiation light beam can be suppressed, the influence of the density of the object to be read is eliminated, and the height of the object to be read can be accurately detected.

In addition, although the threshold value for calculating the irradiation diameter of the light beam is changed in accordance with the density of the object to be read, the beam irradiation position can be detected without being affected by the density of the object to be read. Error can be reduced,
The height of the object to be read can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a perspective view of an image reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an optical system of the apparatus.

FIG. 3A is a schematic diagram when a document is set on the apparatus, and FIG. 3B is a schematic diagram when a light beam is irradiated on the surface of the document in the apparatus.

FIG. 4 is a control circuit block diagram of the present apparatus.

FIG. 5 is a flowchart of the operation of the present apparatus.

FIG. 6 is a side view when the light beam of the present apparatus is applied to a document and a light receiving surface.

FIG. 7 is a view showing a luminance difference of a light beam in the present apparatus.

FIG. 8 is a view showing an example of a one-line image in the present apparatus.

FIG. 9 is a perspective view of an optical system of the device according to the second embodiment of the present invention.

FIG. 10 is a schematic diagram when the surface of a document is irradiated with a light beam in the apparatus.

FIG. 11 is a control circuit block diagram of the above device.

FIG. 12 is a flowchart of the operation of the above device.

FIG. 13 is a flowchart of the operation of the above device.

FIG. 14 is a diagram showing an image of a light beam passage position according to the density of a document.

FIG. 15 is a flowchart of the operation of the device according to a modification of the second embodiment.

FIG. 16 is a flowchart of the operation of the above device.

FIG. 17 is a diagram showing a method of calculating the height of a reading target in the apparatus.

[Explanation of symbols]

 Reference Signs List 6 Platen 11 Scan mirror 13 Lens 14 Image sensor 15 Document (object to be read) 16 Light receiving surface 17 Beam light emitting unit for distance measurement 21 CPU (control means) 30 Scanning mechanism 31 Beam light emitting unit for distance measurement

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G06T 1/00 420 G06T 1/00 430J 430 H04N 1/04 102 (72) Inventor Tsuyoshi Kojima Azuchicho, Chuo-ku, Osaka-shi No.3-13 Osaka International Building Minolta Co., Ltd. F-term (reference) 2F065 AA24 AA32 BB05 DD04 DD09 FF01 FF04 FF09 GG04 GG14 HH05 HH12 JJ03 JJ08 JJ26 LL13 LL62 MM16 QQ03 QQ08 QQ24 QQ25 QQU11A07 SS09 DA15 DA32 FA03 FA07 FA14 FA21 FA45 5B047 AA01 AB02 BA02 BA10 BB02 BC05 BC09 BC11 BC14 CA19 CB11 CB16 DA04 DB01 DB06 DC07 5C072 AA01 BA04 CA02 DA02 DA04 EA05 HA02 HA14 HB04 HB08 HB10 LA12 RA01 UA02 UA06 VA06

Claims (6)

[Claims] 1. A reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read,
An image reading apparatus comprising: a height detecting unit configured to detect an irradiation position of the light beam emitted by the light emitting unit that changes according to a height of the object to be read, and to detect a height of the object to be read. A light-receiving surface for receiving the light beam emitted by the light-emitting means, which is located on an extension of the surface on which the light-emitting means is located, and The boundary is read from the luminance data, and the height of the object to be read is detected.The light emitting unit irradiates a linear beam light to the light receiving surface, and is shielded by the edge of the object to be read. An image reading apparatus for irradiating an object to be read which forms a part on which a light beam is not irradiated on the light receiving surface. 2. An illumination angle of the light beam by the light emitting means is set to an obtuse angle than a reading angle of an optical lens provided in the reading means, and the brightness of the light irradiation part of the light beam and the light shielding part by the object to be read. 2. The image reading apparatus according to claim 1, wherein the height is detected by detecting a difference. 3. A reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read,
A height detecting unit for detecting a height of the object to be read by detecting an irradiation position of the light beam by the light emitting unit by optical scanning of a sensor; Setting means for setting a threshold value of a luminance value for discriminating between an irradiation part and a part other than the irradiation part of the light beam; and a luminance value equal to or greater than the threshold value set by the setting means for the light beam irradiated on the object to be read. An image reading device comprising: a control unit that reads a width of a light beam having the following at each detection point by the sensor, and changes a light beam output by the light emitting unit according to the width. 4. The method according to claim 1, wherein the control unit determines a light beam output by the light emitting unit at a next detection point based on a width of the light beam having a luminance value equal to or greater than a threshold value at a plurality of detection points. The image reading device according to claim 3. 5. A reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read,
An image reading apparatus comprising: a height detecting unit configured to detect an irradiation position of the light beam by the light emitting unit by optical scanning of a sensor and to detect a height of the object to be read, wherein the light beam is irradiated by the light emitting unit. An image reading apparatus which detects a background luminance value near a position in the main scanning direction of the sensor for every line in the main scanning direction, and sequentially changes a light beam output of the light emitting means in accordance with the detected luminance. 6. A reading means for reading an object to be read, a light emitting means for irradiating a light beam obliquely to the object to be read,
A height detecting unit for detecting a height of the object to be read by detecting an irradiation position of the light beam by the light emitting unit by optical scanning of a sensor, wherein the height detecting unit comprises: The sensor detects an irradiation diameter that varies depending on the position where the light beam is irradiated by the means and the density of the object to be read, and detects the height using the information, and calculates the irradiation diameter of the light beam. An image reading apparatus comprising control means for changing a threshold value according to the density of an object to be read.