JPH0869215A - Original size detecting device - Google Patents

Abstract

PURPOSE: To prevent a user from having an illusion and to improve workability by clearly distinguishing between scanning for detecting length in a subscanning direction in the case of detecting original size and ordinary scanning in the case of original reading operation. CONSTITUTION: This device is equipped with at least one original size detecting sensor 110 arranged in order to detect the size in the longitudinal direction of the original 101, a scanner controller 205 functioning as a read control means for reading plural lines of original images in the subscanning direction by using a CCD image sensor 109 by controlling a 1st optical carriage 105, a 2nd optical carriage 107 and the CCD image sensor 109 at the time of detecting the original size, and an original size detection part 201 functioning as an original size deciding means for deciding the original size based on the plural lines of the original images in the subscanning direction read by the sensor 109 and the detected result by the sensor 110.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document size detecting device for detecting the size of a document placed on a platen glass.

[0002]

2. Description of the Related Art In an image forming apparatus typified by a digital copying machine, a document placed on a platen glass has a first optical carriage having a light source mirror and a second optical carriage having a pair of roof mirrors. The reflected light of the original scanned by these mirrors is guided by the lens to the CCD
The original image is converted into an electric signal by forming an image on the image sensor. Especially in a copying machine, CC is usually used.
The image obtained from the D image sensor is processed, such as zooming, and then a copy image is formed. In addition to this, the information obtained from the CCD image sensor must be directly read by the computer and saved. There is also.

As described above, in the copying machine, it is necessary to select a transfer paper of an appropriate size according to the size of the original and the magnification, but the user can copy the original without any special operation. It is self-evident that it is desirable that the optimum transfer paper is automatically selected just by setting it on the platen glass. Therefore, for example, Japanese Unexamined Patent Publication No. 61-2093
An automatic document size detection method is used as disclosed in Japanese Patent Laid-Open No. 6 “Automatic Document Size Recognition Device for Electronic Copier”. In this device, multiple sensors are arranged on the platen glass, and by these multiple sensors,
The size of the original placed on the platen glass is detected.

Another automatic original size detecting method is disclosed in, for example, Japanese Patent Laid-Open No. 5-207239, "Original size detecting device". This document size detecting device turns on the light source of the first optical carriage after the user turns on the switch, scans one position of the document, and scans the document information on the CCD image sensor from the information of the document to determine the width scanning direction. In addition to detecting the length of the document, the length of the document in the longitudinal direction is detected by a sensor provided separately, and the document size is determined by combining these information and scanning for document reading is performed.

By automatically detecting the document size in this way, the burden on the user can be reduced.

[0006]

However, according to Japanese Patent Application Laid-Open No. 5-207239, the copy switch is turned off.
After N, the document size is detected prior to the document reading operation, and the scanning for length detection in the sub-scanning direction in the document size detection and the scanning during the normal document reading operation can be distinguished. Since it is difficult to understand, the user may have the illusion that the document reading operation has finished when the document size detection ends, and this may cause the original to be removed from the platen glass or the original to be removed before the document reading operation starts. There was a problem in that the desired image data could not be obtained at one time because it was moved, and it was necessary to read the document again, and the workability deteriorated.

Further, since the scanning for detecting the length in the sub-scanning direction in the document size detection is performed in the same manner as the scanning during the normal document reading operation, the scanning for the document size detection is performed more than necessary. There was also the problem that it took time.

Further, since it is assumed that the document size is detected with the document pressing plate closed, the back side (platen glass side) of the document pressing plate must be colored with a color different from that of the document. Therefore, there is a problem that the original pressing plate cannot be accurately detected when the original pressing plate is significantly soiled or when an original having a ground color substantially the same as the original pressing plate is used.

Further, when the document size is detected with the document pressing plate left open, the light source of the first optical carriage emits light with high brightness as in the normal image reading operation. There is also a problem in that the high-brightness illumination gives a user discomfort such as dazzling.

The present invention has been made in view of the above, and clearly distinguishes between scanning for length detection in the sub-scanning direction in document size detection and scanning during normal document reading operation, and the The purpose is to eliminate the illusion of and improve workability.

Further, the present invention has been made in view of the above, and it is an object of the present invention to shorten the time required for detecting the size of a document.

Further, the present invention has been made in view of the above, so that the user does not feel uncomfortable such as dazzling even when the document size is detected with the document pressing plate left open. The purpose is to do.

Further, the present invention has been made in view of the above, and an object of the present invention is to always accurately detect the size of an original without being affected by the color and stain of the original pressing plate. To do.

[0014]

In order to achieve the above object, a document size detecting device according to a first aspect of the present invention comprises a first optical carriage having a light source and a mirror, and a second optical carriage having a pair of roof mirrors. The carriage is used to scan the original placed on the platen glass, and the reflected light of the original is CC-scanned.
In a document size detection device applied to an image reading device that reads a document image by photoelectrically converting it with a D image sensor, at least a device arranged to detect the size in the longitudinal direction of a document placed on the platen glass. One original size detection sensor, and at the time of detecting the original size, the first optical carriage, the second optical carriage, and the CCD image sensor are controlled so that the CCD image sensor produces original images for a plurality of lines in the sub-scanning direction. Document size determination for determining the document size based on the reading control means for reading, the document image for a plurality of lines in the sub-scanning direction read by the CCD image sensor, and the size in the longitudinal direction of the document detected by the document size detection sensor And means.

Further, in the document size detecting apparatus according to the second aspect, the document size determining means inputs the document images for a plurality of lines in the sub-scanning direction read by the CCD image sensor, and the sub-scanning for each pixel is performed. A mean value processing means for obtaining a mean value in the direction and a binarization processing for comparing the mean value for each pixel obtained by the mean value processing means with a preset threshold value and outputting a binary signal. And means.

In the document size detecting device according to the third aspect, the reading control means controls the light source so that the light amount at the time of detecting the document size is smaller than the light amount at the time of reading the document.

Further, in the document size detecting device according to a fourth aspect, the reading control means reads the document image of a plurality of lines in the sub-scanning direction by the CCD image sensor while the light amount of the light source rises. .

Further, in the document size detecting device according to a fifth aspect, the reading control means is configured to detect the CC when the document size is detected.
The number of pixels of the document information read by the D image sensor is C
The number is smaller than the number of pixels for one line of the CD image sensor.

Further, in the document size detecting device according to the sixth aspect, the reading control means makes the accumulation time in the CCD image sensor at the time of detecting the document size shorter than the accumulation time in the CCD image sensor at the time of reading the document. Is.

According to a seventh aspect of the present invention, there is provided a document size detecting device including a first optical carriage having a light source and a mirror.
An image reading apparatus that scans an original placed on a platen glass by using a second optical carriage having a pair of roof mirrors, and photoelectrically converts reflected light of the original by a CCD image sensor to read an original image. In the applied document size detection apparatus, a document pressing plate that presses a document placed on the platen glass, an opening degree detecting unit that detects an opening degree of the document pressing plate, and a document is placed on the platen glass. Document presence / absence detecting means for detecting whether or not the document is placed, at least one document size detection sensor arranged to detect the size of the document placed on the platen glass in the longitudinal direction, and the document presence / absence Determination means for determining whether or not to detect the document size based on the detection result of the detection means and the openness detected by the openness detection means. When it is determined by the determination means that the document size is detected, the first optical carriage, the second optical carriage and the CCD image sensor are controlled so that the CCD image sensor scans a plurality of originals in the sub-scanning direction. Reading control means for reading an image,
Document size determining means for determining the size of the document based on the document images of a plurality of lines in the sub-scanning direction read by the CCD image sensor and the size of the document in the longitudinal direction detected by the document size detection sensor Is.

[0021]

The document size detecting device (claim 1) of the present invention is
The reading control means controls the first optical carriage, the second optical carriage, and the CCD image sensor at the time of detecting the document size, and the CCD image sensor reads the document images of a plurality of lines in the sub-scanning direction. Next, the document size determination means determines the size of the document based on the document images of a plurality of lines in the sub-scanning direction read by the CCD image sensor and the size of the document in the longitudinal direction detected by the document size detection sensor. Therefore, the document size is detected only by scanning a plurality of lines in the sub-scanning direction.

Further, in the document size detecting apparatus of the present invention (claim 2), the average value processing means of the document size determining means is C
A document image for a plurality of lines in the sub-scanning direction read by a CD image sensor is input, an average value in the sub-scanning direction for each pixel is obtained, and the binarization processing means obtains the average value for each pixel and the average value in advance. By comparing the set threshold value and outputting a binary signal, the document size can be determined by using the average value of a plurality of lines for each pixel, so that the document size detection accuracy is improved.

Further, in the document size detecting device of the present invention (claim 3), the reading control means controls the light source so that the light amount at the time of detecting the document size is smaller than the light amount at the time of reading the document. It becomes difficult to feel discomfort such as glare.

Further, in the document size detecting apparatus of the present invention (claim 4), the reading control means controls the CCD image sensor to read the document images of a plurality of lines in the sub-scanning direction from the middle of the rise of the light amount of the light source. By doing
The time required to detect the document size is reduced.

Further, in the document size detecting apparatus of the present invention (claim 5), the reading control means is configured to detect the CCD when detecting the document size.
The number of pixels of the document information read by the image sensor is CC
By reducing the number of pixels for one line of the D image sensor, the time required for detecting the document size is shortened.

Further, in the document size detecting device of the present invention (claim 6), the reading control means makes the accumulation time in the CCD image sensor when detecting the document size shorter than the accumulation time in the CCD image sensor when reading the document. As a result, the time required for detecting the document size is shortened.

Further, the document size detection device of the present invention (claim 7) determines whether or not to detect the document size based on the detection result of the document presence / absence detection means and the openness detected by the openness detection means. If it is determined that the document size is detected, the first optical carriage, the second optical carriage, and the CCD image sensor are controlled, and the CCD image sensor reads a document image for a plurality of lines in the sub-scanning direction. Detects the openness of the document holding plate by determining the size of the document based on the scanned document images for multiple lines in the sub-scanning direction and the size of the document in the longitudinal direction detected by the document size detection sensor. It is used as a trigger for starting, and detects the size of the original during the closing operation of the original pressing plate.

[0028]

Embodiments [First Embodiment], [Second Embodiment], [Third Embodiment], [Fourth Embodiment], [Fifth Embodiment], [Embodiment 6] of the document size detecting device of the present invention are described below. Will be described in detail with reference to the drawings.

[Embodiment 1] FIG. 1 is a basic configuration diagram of a digital image reading apparatus to which the document size detection apparatus of Embodiment 1 is applied. A platen glass 102 for placing the original 101 and a light source 103 for irradiating the original 101 with light
A mirror 104 for reflecting the reflected light of the light source 103 reflected by the original 101 in a predetermined direction;
First optical carriage 105 on which a mirror 104 is mounted
And a pair of roof mirrors 1 for guiding the reflected light reflected by the mirror 104 toward the CCD image sensor 109.
06, and a lens 108 for condensing the reflected light of the original 101 guided by the first optical carriage 105 and the second optical carriage 107.
And input the reflected light condensed by the lens 108,
A CCD image sensor 109 that performs photoelectric conversion and outputs as an electric signal, and a document size detection sensor 110 that detects the size of the document 101 placed on the platen glass 102 in the longitudinal direction are provided. Here, the document size detection sensor 110 detects whether or not there is a document.

In the above structure, the light emitted from the light source 103 is reflected by the original 101 placed on the platen glass 102, and the reflected light is transmitted to the lens 108 via the mirror 104 and the pair of roof mirrors 106. Sent. The lens 108 collects the reflected light guided by the mirror 104 and the pair of roof mirrors 106 on the CCD image sensor 109, and the CCD image sensor 109 performs photoelectric conversion to read the image of the original 101 as an electric signal.

Next, with reference to FIG. 2, a schematic configuration of the document size detecting apparatus according to the first embodiment will be described. FIG. 2 is a block diagram of the document size detecting device according to the first embodiment,
A document size detection unit that detects the size of the document based on the document images (electrical signals) of a plurality of lines in the sub-scanning direction read by the CCD image sensor 109 and the size of the document in the longitudinal direction detected by the document size detection sensor 110. 201, CCD image sensor 109, and light source 1
03, a lamp regulator 202, a motor 203 for moving the first optical carriage 105 and the second optical carriage 107, a motor driver 204 for driving the motor 203, a motor driver 204 for detecting a document size, The CCD image sensor 10 is controlled by controlling the lamp regulator 202.
9, a scanner controller 205 for reading the document images of a plurality of lines in the sub-scanning direction.

In the structure of the document size detecting device, the scanner controller 205, the lamp regulator 202, the motor 203, the motor driver 2
04 light source 103, first optical carriage 105, second optical carriage 107 and CCD image sensor 109
Generally uses a mechanism installed in an image reading device.

FIG. 3 shows the circuit configuration of the document size detecting section 201 and the image processing section of the image reading apparatus. The image processing section of the image reading apparatus is the CCD image sensor 10.
Electrical signal output from 9 (here, analog signal)
A / D conversion circuit 304 for converting the digital signal into a digital signal,
A shading correction circuit 305 that inputs the digital signal output from the D / D conversion circuit 304 and corrects the variation of the light amount distribution of the light source 103 and the variation of the sensitivity of each light receiving element of the CCD image sensor 109; An image processing circuit 306 for performing various kinds of image processing such as processing, scaling processing, moving processing, etc., and a separation circuit 307 for inputting the digital signal subjected to the image processing and separating it into a character portion and a halftone portion are provided. . The digital signal output from the separation circuit 307 is input to a printer (not shown) or the like connected to the image reading device.

On the other hand, the original size detecting section 201 is a CCD
An average value for inputting a digital signal obtained by converting an analog signal (original image) for a plurality of lines in the sub-scanning direction read by the image sensor 109 by the A / D conversion circuit 304 and obtaining an average value in the sub-scanning direction for each pixel. A processing circuit 301, a binarization processing circuit 302 that outputs a binary signal by comparing an average value for each pixel obtained by the average value processing circuit 301 with a preset threshold value, and a binarization processing circuit 302 Processing circuit 302
And a document size determination processing circuit 303 for determining the size of the document based on the size of the document in the longitudinal direction detected by the document size detection sensor 110.

The operation of detecting the size of a document in the above configuration will be described. When detecting the document size,
The scanner controller 205 turns on the light source 103 in the width direction of the original 101, and then scans a part of the original 101 with the first optical carriage 105 and the second optical carriage 107. At this time, the CCD image sensor 109 reads data (original image) for a plurality of lines in the sub-scanning direction. The electrical signal of the read data is A / D
It is converted into a digital signal by the conversion circuit 304 and output to the average value processing circuit 301.

The average value processing circuit 301 takes an average value in the sub-scanning direction for each pixel. At this time, data having a value far apart from other data may be ignored.

The binarization processing circuit 302 inputs the average value from the average value processing circuit 301, compares it with a preset threshold value, and based on the magnitude relation with the threshold value,
It is converted (binarized) into a binary signal of "0" and "1". The threshold value at this time is preferably set to a value between the reflectance when the original 101 is present and the reflectance when the original 101 is not present. The threshold value may be set by obtaining an intermediate value from the data read by the CCD image sensor 109.

In the original size determination processing circuit 303, the size of the original 101 in the width direction is determined from the binarized data of the CCD image sensor 109, and the original size detection is provided separately in the length direction. Sensor 11
Judge by 0. By combining these two pieces of information, it is possible to reliably detect the document size.

As described above, according to the first embodiment, when the document size is detected, the first optical carriage 105 and the second optical carriage 107 scan the document 101 in the sub-scanning direction, and the CCD image sensor 109 Then, the data of a plurality of lines in the sub-scanning direction is read, and the size of the original 101 is determined based on the read data and the detection result of the original size detection sensor 110. Therefore, since scanning for a plurality of lines in the sub-scanning direction is performed during document size detection, it is necessary to clearly distinguish between scanning for length detection in the sub-scanning direction in document size detection and scanning during normal document reading operation. ， The illusion of the user can be eliminated and the workability can be improved. Further, the time required for detecting the document size can be shortened.

Further, since scanning is performed for a plurality of lines in the sub-scanning direction, even when the document size is detected with the document pressing plate left open, the user's discomfort such as dazzling can be reduced. .

Further, the data of a plurality of lines in the sub-scanning direction read by the CCD image sensor 109 are averaged by the average value processing circuit 301, and then the average value and the threshold value are compared to perform binarization. , Noise (data having a value far apart from other data) can be removed, and the size detection accuracy of the original 101 can be improved.

[Second Embodiment] A document size detecting apparatus according to the second embodiment is the same as the document size detecting apparatus according to the first embodiment.
The light quantity of 03 is changed. Since the basic configuration and operation are the same as those in the first embodiment, only different parts will be described here.

In the second embodiment, in the scanning of the document size detection, the scanner controller 205 controls the lamp regulator 202 (that is, the light source 10) so that the light amount at the time of detecting the document size becomes smaller than the light amount at the time of reading the document.
3) is controlled. Since it is sufficient to determine the presence or absence of the original 101 when detecting the original size, there is no problem even if the light amount is low and the dynamic range is narrowed.

Therefore, the scanner controller 304
As shown in FIG. 2, when a document size is detected, a control signal for lowering the light amount of the light source 103 is output to the lamp regulator 202, and the lamp regulator 202 turns on the light source 103 with the instructed light amount.

As described above, in the second embodiment, the light amount of the light source 103 to be turned on is smaller than the light amount of the light source 103 to be turned on at the time of reading the document, so that the user needs a longer time than necessary. ， Reduces unpleasant trouble without being exposed to high-luminance lighting. Further, it is possible to reduce the possibility that the user may feel that the reading of the original is finished just by finishing the detection of the original size. That is, the discomfort can be further reduced and the illusion can be avoided as compared with the first embodiment.

[Third Embodiment] In addition to the document size detection apparatus of the first embodiment, the original size detection apparatus of the third embodiment has a light source 10
The CCD image sensor 109 reads out data for a plurality of lines in the sub-scanning direction from the middle of the rising of the light amount of No. 3. Since the basic configuration and operation are the same as those in the first embodiment, only different parts will be described here.

FIG. 4 shows the relationship between the rise time and the amount of light when a fluorescent lamp is used as the light source 103. It takes about 10 ms until the fluorescent lamp is saturated, and during normal document reading, data is read from the CCD image sensor 109 after waiting 10 ms or more after turning on the fluorescent lamp. However, when detecting the document size, there is no problem even if the light amount of the light source 103 is low as described in the second embodiment. Therefore, for example, the scanner controller 205 waits 5 ms after turning on the light source (fluorescent lamp) 103 and then the CCD image. Control is performed to read data from the sensor 109.
The light source 103 is not limited to the fluorescent lamp.

As described above, in the third embodiment, the CCD is detected from the middle of the rising of the light amount of the light source 103 at the time of detecting the document size.
Since the image sensor 109 reads out data for a plurality of lines in the sub-scanning direction, the time required for detecting the document size can be further shortened.

[Fourth Embodiment] In addition to the document size detecting device of the first embodiment, the document size detecting device of the fourth embodiment controls the information read from the CCD image sensor 109 to less than one line when detecting the document size. It is a thing. Since the basic configuration and operation are the same as those in the first embodiment, only different parts will be described here.

FIG. 5 shows the relative relationship of each paper size in the width direction of the original 101, and here, the back side of the platen glass 102 will be described as the alignment of the original. Also, a case will be described in which the document size is detected as A5 portrait / landscape size, A4 portrait / landscape size, A3 landscape size, B5 portrait / landscape size, and B4 landscape size.

In order to judge the length of one side of the original, the longest A3 horizontal size, A4 vertical size to the shortest A5 of the original are determined.
The original size can be determined by detecting the length of the horizontal size. At the time of detecting the document size, detection is performed from the front side of the platen glass 102, and the range from the front side of the longest A3 horizontal size and A4 vertical size to the front side of the shortest A5 horizontal size is set as the document size detection range. And Fig. 5
As shown in the figure, it is indicated by an arrow (f) 501.

When reading data from the front side of the platen glass 102 in the CCD image sensor 109, the data in the range indicated by arrow (e) 502 is read at the time of reading the original. When detecting the document size, the length of one side of the document can be determined if the range indicated by arrow (f) 501 is read. After reading the document size detection range, the CCD image sensor 109 is reset and the next reading is performed. Since it can be performed, the reading cycle can be made earlier than when reading a document.

Further, when reading data from the back side of the CCD image sensor 109, the entire range shown by the arrow (e) 502 in the drawing may be read when reading the original, or only the range of the detected original size is read. May be. When the document size is detected, it is not necessary to take in data before the document size detection range of arrow (f) 501, so the shift lock cycle for reading the document is selected to the faster one, and the arrow of (f) 501 is selected. When reading the document size detection range, the document reading cycle can be accelerated by reading the document with the shift lock of the document reading cycle.

As described above, in the fourth embodiment, the information read from the CCD image sensor 109 is detected to be less than one line when the document size is detected. Therefore, the document reading cycle can be further shortened and the time can be shortened. Can be achieved.

[Fifth Embodiment] In addition to the original size detecting device of the first embodiment, the original size detecting device of the fifth embodiment controls the accumulation time of the CCD image sensor 109. Since the basic configuration and operation are the same as those in the first embodiment, only different parts will be described here.

FIG. 6 shows the output characteristic of the reflectance of the CCD image sensor 109. CCD reading accuracy
It depends on the S / N ratio of the image sensor 109. Therefore, the accumulation time of the CCD image sensor 109 is set so that a saturated output can be obtained when white is read. In other words, this accumulation time is set so that highly accurate reading can be performed.

However, since the accuracy is not required when detecting the document size as compared with when reading the document, there is no problem even if the accumulation time of the CCD image sensor 109 when detecting the document size is shortened to lower the accuracy. Therefore, Example 5
Then, as shown in FIG. 6, the accumulation time is set to 8 ms during normal document reading, and the accumulation time is set to 4 ms during document size detection.

As described above, in the fifth embodiment, when the document size is detected, the storage time of the CCD image sensor 109 is controlled to be shorter than that during normal document reading. Therefore, the document reading time from the CCD image sensor 109 is shortened. can do.

[Sixth Embodiment] The document size detecting apparatus according to the sixth embodiment detects the detection result of the document presence / absence detecting means for detecting whether or not the document is placed on the platen glass and the open degree of the document pressing plate. Based on the openness detected by the openness detecting means, it is determined whether or not the document size is detected. The basic configuration and operation are the same as in the first embodiment.
As it is similar to the fifth embodiment, only different parts will be described here.

FIG. 7 shows the configuration of the document presence / absence detecting means and the open degree detecting means of the sixth embodiment. 2 illustrates two types of sensors provided to determine the start of document size detection. As the openness detecting means for detecting the openness of the document pressing plate 701, for example, a photo interrupter 702 and a filler 703 attached to the document pressing plate 701 can be used. The openness of 701 can be detected within a certain angle range. As the openness detecting means, it is needless to say that the openness of the document pressing plate 701 may be detected by a reed switch or the like.

As the document presence / absence detecting means, as shown in the drawing, an infrared light generator 704 for detecting the presence / absence of a document at a position facing the platen glass 102, and an infrared light generator 704 are emitted. Light is platen glass 102
A document presence / absence detection sensor 706 including a photo sensor 705 that receives reflected light reflected from the document placed on the document is used. However, the document presence detection sensor 706 is the first
It may be on the optical carriage of or at another place.

Now, the process up to the detection of the document size in the sixth embodiment will be described with reference to the follow chart of FIG. When the user wants to read an image, first, the document pressing plate 701 is opened to set the document.
In the sixth embodiment, when the document pressing plate 701 is opened by a certain angle (here, 25 degrees) or more (S801), the document presence detection sensor 706 starts operating (S80).
2). At this time, since the light emitted from the document presence / absence detection sensor 706 is infrared light, the user cannot recognize that it is emitting light. Of course, the certain fixed angle of the document pressing plate 701 does not have to be 25 degrees.

When the document is placed on the platen glass 102, the output of the photo sensor 705 becomes large and it is judged that there is a document (S803). When attempting to scan a document, normally, after placing the document, the document holding plate 70
1 is closed and the original is pressed onto the platen glass 102. When the document pressing plate 701 is closed more than a certain angle, the photo sensor 705 and the filler 703 detect that the opening degree is less than this angle (S80).
4). After that, as described in the second embodiment, the scanner controller 205 turns on the light source 103 with the light amount lower than that at the time of reading the original (S805), and the light source 103
Before the image is saturated, the motor 203 is turned on to start the document size detection (prescan) (S806).

The reflected light of the original is imaged on the CCD image sensor 109 following the path of the first embodiment, and the data passes through the average value processing circuit 301 and the binarization processing circuit 302 and the original size determination processing circuit. It is input to 303. The document size determination processing circuit 303 determines the document size based on the above data and the output of the document size detection sensor 110 (S807). On the other hand, in S804, when the original is a book or the like, the original is sometimes read with the original pressing plate 701 opened. In this case, immediately after the document reading switch is turned on, the light source 103 is turned on to detect the document size (S808). As described in the second embodiment, even if the light source 103 is turned on with the document pressing plate 701 opened, the light amount is pressed so low that it does not feel dazzling.

In S807, as described in the fourth embodiment, the range read from the CCD image sensor 109 is the original size detection range indicated by the arrow (f) 501 shown in FIG. As described in 5, the storage time of the CCD image sensor 109 is controlled to be short.

As described above, in the sixth embodiment, the presence or absence of the original is detected by the open degree of the original pressing plate to detect the original size, so that the user's work is not increased and the reading time of the original is reduced. It can be shortened.

[0067]

According to the document size detecting apparatus of the present invention (claim 1), the reading control means detects the document size when
First optical carriage, second optical carriage and CCD
By controlling the image sensor, the CCD image sensor reads the original image of a plurality of lines in the sub-scanning direction. Next, the document size determination means determines the size of the document based on the document images of a plurality of lines in the sub-scanning direction read by the CCD image sensor and the size of the document in the longitudinal direction detected by the document size detection sensor. Therefore, since the document size is detected only by scanning a plurality of lines in the sub-scanning direction, the distinction between the scan for detecting the length in the sub-scanning direction in the document size detection and the scan during normal document reading operation is clarified. And eliminate the illusion of the user,
Workability can be improved.

Further, in the document size detecting apparatus of the present invention (claim 2), the average value processing means of the document size determining means is C
A document image for a plurality of lines in the sub-scanning direction read by a CD image sensor is input, an average value in the sub-scanning direction for each pixel is obtained, and the binarization processing means obtains the average value for each pixel and the average value in advance. By comparing the set threshold value and outputting a binary signal, it is possible to determine the document size using the average value of a plurality of lines for each pixel, so that the document size detection accuracy is improved, The time required to detect the document size can be shortened.

According to the document size detecting device of the present invention (claim 3), the reading control means controls the light source so that the light amount at the time of detecting the document size is smaller than the light amount at the time of reading the document. Since it is difficult to feel discomfort such as glare, it is possible to prevent the user from feeling discomfort such as dazzling even when the document size is detected with the document pressing plate left open.

Further, in the document size detecting device of the present invention (claim 4), the reading control means controls the CCD image sensor to read the document images of a plurality of lines in the sub-scanning direction from the middle of the rise of the light amount of the light source. By doing
The time required to detect the document size is reduced.

Further, in the document size detecting device of the present invention (claim 5), the reading control means is configured to detect the CCD when detecting the document size.
The number of pixels of the document information read by the image sensor is CC
By reducing the number of pixels for one line of the D image sensor, the time required for detecting the document size is shortened.

Further, in the document size detecting device of the present invention (claim 6), the reading control means makes the accumulation time in the CCD image sensor when detecting the document size shorter than the accumulation time in the CCD image sensor when reading the document. As a result, the time required for detecting the document size is shortened.

Further, the document size detection device of the present invention (claim 7) determines whether or not to detect the document size based on the detection result of the document presence / absence detection means and the openness detected by the openness detection means. If it is determined that the document size is detected, the first optical carriage, the second optical carriage, and the CCD image sensor are controlled, and the CCD image sensor reads a document image for a plurality of lines in the sub-scanning direction. Detects the openness of the document holding plate by determining the size of the document based on the scanned document images for multiple lines in the sub-scanning direction and the size of the document in the longitudinal direction detected by the document size detection sensor. It is used as a start trigger, and the original size is detected during the closing operation of the original pressing plate. Effect without being always able to allow the detection of the document size accurately.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a digital image reading apparatus to which a document size detecting apparatus according to a first exemplary embodiment is applied.

FIG. 2 is a block diagram of a document size detection device according to the first exemplary embodiment.

FIG. 3 is a configuration diagram illustrating a part of control of a reading unit according to the second embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a rising time and a light amount when a fluorescent lamp is used as a light source of Example 3.

FIG. 5 is an explanatory diagram showing a relative relationship between respective paper sizes in a width direction of an original according to the fourth embodiment.

FIG. 6 is an explanatory diagram showing an output characteristic of reflectance of the CCD image sensor 109 according to the fifth embodiment.

FIG. 7 is an explanatory diagram showing the configurations of a document presence detection unit and an openness detection unit according to a sixth embodiment.

FIG. 8 is a follow-up chart showing a document size detection according to the sixth embodiment.

[Explanation of symbols]

101 original 102 platen glass 103 light source 104 mirror 105 first optical carriage 106 roof mirror 107 second optical carriage 108 lens 109 CCD image sensor 110 original size detection sensor 201 original size detection unit 202 lamp regulator 203 motor 204 motor driver 205 scanner controller 301 Average value processing circuit 302 Binarization processing circuit 303 Original size determination processing circuit 304 A / D conversion circuit 305 Shading correction circuit 306 Image processing circuit 307 Separation circuit 501 Arrow (f) 502 Arrow (e) 701 Original pressing plate 702 Photo Interrupter 703 Filler 704 Infrared light generator 705 Photo sensor 706 Original presence / absence detection sensor

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideyuki Takemoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (7)

[Claims] 1. An original placed on a platen glass is scanned using a first optical carriage having a light source and a mirror and a second optical carriage having a pair of roof mirrors, and reflected light from the original is scanned. In a document size detection device applied to an image reading device that reads a document image by photoelectrically converting with a CCD image sensor, at least a device arranged to detect the size of a document placed on the platen glass in the longitudinal direction. One original size detection sensor, the first optical carriage when detecting the original size,
Reading control means for controlling the second optical carriage and the CCD image sensor to read an original image of a plurality of lines in the sub-scanning direction by the CCD image sensor, and a plurality of lines in the sub-scanning direction read by the CCD image sensor. A document size detecting device, comprising: a document size determining unit that determines the size of the document based on the document image and the size of the document in the longitudinal direction detected by the document size detection sensor. 2. The original size determining means is the CCD
An average value processing means for inputting document images for a plurality of lines in the sub-scanning direction read by an image sensor and obtaining an average value in the sub-scanning direction for each pixel, and an average value processing means for each pixel determined by the average value processing means 2. The document size detecting apparatus according to claim 1, further comprising a binarization processing unit that compares the average value with a preset threshold value and outputs a binary signal. 3. The document size detecting apparatus according to claim 1, wherein the reading control unit controls the light source so that the light amount when detecting the document size is smaller than the light amount when reading the document. 4. The reading control means controls the CCD image sensor to read a document image for a plurality of lines in the sub-scanning direction while the light amount of the light source is rising. Document size detection device. 5. The reading control means sets the number of pixels of the document information read by the CCD image sensor at the time of detecting the document size to be smaller than the number of pixels for one line of the CCD image sensor. Original size detection device. 6. The document size according to claim 1, wherein the reading control means sets a storage time in the CCD image sensor at the time of detecting the document size to be shorter than a storage time in the CCD image sensor at the time of reading the document. Detection device. 7. An original placed on a platen glass is scanned by using a light source and a first optical carriage having a mirror and a second optical carriage having a pair of roof mirrors, and reflected light of the original is scanned. In a document size detecting device applied to an image reading device that reads a document image by photoelectrically converting it with a CCD image sensor, a document pressing plate for pressing a document placed on the platen glass, and an opening degree of the document pressing plate. Openness detecting means for detecting the presence of a document, document presence detecting means for detecting whether or not a document is placed on the platen glass, and size of a document placed on the platen glass in the longitudinal direction. At least one document size detection sensor arranged for that purpose, the detection result of the document presence / absence detection means, and the open degree detected by the open degree detection means. Determination means for determining whether to detect the document size based on the above, and the first optical carriage, the second optical carriage, and the CCD image sensor when the determination means determines that the document size is detected. And a reading control means for reading a document image of a plurality of lines in the sub-scanning direction by the CCD image sensor, and a document image of a plurality of lines in the sub-scanning direction read by the CCD image sensor and a document size detection sensor. An original size detecting device comprising: an original size determining unit that determines the size of the original based on the detected size of the original in the longitudinal direction.