JP2011077759A - Image reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce costs by exactly detecting original size and suppressing increase in memory capacity. <P>SOLUTION: The image reader includes: a generation means 23 for receiving reflected light from an original on an original platen by a plurality of light-receiving elements to generate light-receiving data for each pixel of each light-receiving element; a calculation means 31 for comparing the light-receiving data generated by the generation means 23 for each pixel of each light-receiving element to calculate the maximum value for each pixel; a storage means 36 for storing the maximum value of the receiving data for each pixel of each light-receiving element into a predetermined area as data for detecting the original size; a determination means 31 for determining presence/absence of the original on the original platen by whether the data for detecting the original size for each pixel of each light-receiving element stored in the storage means 36 exceeds a threshold, thereby deciding the original size in the main-scanning direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image reading device that detects the size of a document placed on a document table in the main scanning direction, and an image forming apparatus including the image reading device.

  2. Description of the Related Art Conventionally, image forming apparatuses such as scanners and copiers have been provided with an image reading device for reading an image of a document placed on a document table. Means for detecting the size of the document placed in the main scanning direction.

  In this type of general detection means, the original mat opening / closing detection switch detects that the original mat is closed, and the received light data from the sensor acquired at that time is stored in a memory for each pixel, and each received light data Determines that there is a document and determines the document size.

  In addition, in order to further improve the accuracy of detecting the document size, the open state before the document mat is closed is detected, and the light reception data from the sensor acquired at that time is always monitored, so that the light is incident from outside the document. There has also been proposed a technique for detecting disturbance light such as a fluorescent lamp and removing the disturbance light component from received light data obtained from the sensor when the original mat is closed (see, for example, Patent Document 1).

  On the other hand, in recent years, it has become necessary to detect color originals with the colorization of image reading apparatuses. However, when a single color sensor is used to detect a color original when it is detected, for example, it is placed on an original table. If the red document is detected by a sensor that has sensitivity to green, the red document on the document table cannot be detected because the green light is not reflected from the red document. May occur. Therefore, in such a case, in order to accurately detect a color document, a plurality of color light receiving elements (CCD (Charge-Coupled Device) sensors) are provided in the sensor, and an original detection operation is performed for each color light receiving element. Is going.

JP-A-9-135330

  However, when using a plurality of color line sensors as described above, since the original is detected for each color, it is necessary to store the sampled received light data in the memory for each color sensor. For this reason, there is a problem that the memory capacity of the image processing IC increases, resulting in an increase in cost.

  In this method, in order to remove noise, it is determined that there is a document on the document table when a predetermined number of pixels determined to exceed a predetermined threshold value for each color are continuously detected. If the color changes continuously, the document is falsely detected as having no document because a predetermined number of pixels that are determined to exceed the predetermined threshold are not consecutive, even though the document is placed on the document table. There is a possibility that.

  On the other hand, when detecting a document in consideration of disturbance light as described above, it is necessary to store sampling data for extracting disturbance light components for each color in addition to the light reception data. For example, when three light receiving elements of RGB (red / green / blue) 7500 pixels are used to read an image of a color original, RGB 3 is used in two areas for disturbance light component sampling and original size sampling. A memory for color (that is, 7500 × 2 area × 3 colors × image data gradation (bit)) is required. For this reason, there is a problem that the memory capacity of the image processing IC is further increased, resulting in a cost increase.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. An image reading apparatus and an image forming apparatus that can accurately detect a document size, suppress an increase in memory capacity, and reduce costs. An object is to provide an apparatus.

  In order to achieve the above-described object, the present invention provides an image reading apparatus for detecting the size of a document placed on a document table in the main scanning direction, and receives a plurality of reflected lights from the document on the document table. The light receiving device generates light receiving data for each pixel of each light receiving element, and the light receiving data generated by the generating means is compared for each pixel of each light receiving element, and the maximum value is calculated for each pixel. Calculating means for storing, storing means for storing a maximum value of light receiving data for each pixel of each light receiving element in a predetermined area as document size detection data, and a document for each pixel of each light receiving element stored in the storing means And determining means for determining the document size in the main scanning direction by determining the presence or absence of the document on the document table depending on whether or not the size detection data exceeds a threshold value.

  Further, in the image reading apparatus according to the present invention, the generating unit receives disturbance light by the light receiving elements when the document is placed on the document table with the document mat opened. The disturbance light data is generated for each pixel of the element, the calculation means compares the disturbance light data for each pixel of each light receiving element, calculates the maximum value for each pixel, and the storage means The maximum value of disturbance light data for each pixel of the light receiving element is stored in the predetermined area as disturbance light detection data, and the determination means determines whether or not the disturbance light detection data for each pixel of each light receiving element exceeds a threshold value. The main scanning direction is detected by detecting the presence or absence of disturbance light, detecting a section where a predetermined number of pixels determined to have a document based on the document detection data and determined to have no disturbance light based on the disturbance light detection data Determine the document size It is preferable to that.

  According to the present invention, various excellent effects can be obtained, such as being able to accurately detect the document size, suppressing an increase in memory capacity, and reducing costs.

1 is a schematic diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of an image reading apparatus according to an embodiment of the present invention. FIG. 5 is a diagram illustrating a data storage method when detecting the document size in the image reading apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a schematic diagram showing a schematic configuration of the image reading apparatus according to the embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of the image reading apparatus, and FIG. 3 is a document size in the image reading apparatus. It is a figure which shows the data storage method at the time of a detection.

  As shown in FIG. 1, an image reading apparatus 10 according to an embodiment of the present invention is provided in an image forming apparatus such as a scanner or a copying machine, and includes a transparent glass document table 11 on which a document is placed. A document mat 12 that can be opened and closed above the document table 11, an ADF (Auto Document Feeder) reading glass 13 provided in a strip shape along the main scanning direction at one end of the document table 11, and provided at the other end of the document table 11. The original mat opening / closing detection sensor 14, the first moving carriage 15 and the second moving carriage 16 provided below the original table 11, the white light source 17 and the first reflecting mirror 18 provided on the first moving carriage 15, A second reflecting mirror 19 and a third reflecting mirror 20 provided on the two-moving carriage 16, a motor 21 for driving the first moving carriage 15 and the second moving carriage 16, and an optical A line image sensor 23 for receiving reflected light from a document on the document table 11 through a window 22, and the line image sensor 23 receives a plurality of light lines (for example, three RGB signals) arranged in a line. It is comprised by the element (CCD sensor).

  As shown in FIG. 2, the control of the image reading apparatus 10 is performed by the control unit 30. The control unit 30 analogizes the CPU (Central Processing Unit) 31 that controls the line image sensor 23, the light source 17, the first to third reflection mirrors 18, 19, and 20, and the light reception data from the line image sensor 23. A / D converter 32 for converting from digital to digital, a shading correction unit 33 for correcting the digitized light reception data for each light receiving element, and a RAM (Random-Access Memory) for storing correction data used at this time ) 34, an image processing unit 35 that performs predetermined image processing based on the image of the original read by the line image sensor 23, and a memory 36 that stores received light data of each of the light receiving elements.

  In the image reading apparatus 10 having the above-described configuration, when an original is placed on the original platen 11 and the original mat 12 is closed, the original mat open / close detection sensor 14 is pressed and turned ON, and at that moment, the CPU 31 causes the white light source 17 to be turned on. Lights up. The light from the light source 17 at this time is reflected on the original on the original table 11 and the original mat 12, and then is sequentially reflected on the first reflection mirror 18, the second reflection mirror 19, and the third reflection mirror 20, and the optical lens. 22, and enters each light receiving element of the line image sensor 23.

  Each RGB light receiving element of the line image sensor 23 generates analog light receiving data for each pixel, as shown in FIG. 3, and the A / D converter 32 converts this light receiving data into digital light receiving data. The CPU 31 compares the digitized light reception data for each pixel of each light receiving element, and calculates the maximum value of the light reception data for each pixel. Further, the CPU 31 stores the maximum value of the light reception data for each pixel of each light receiving element as a document size detection data in a predetermined area of the memory 36, and the document size detection data for each pixel of each light reception element exceeds the threshold value. Judge whether or not. As a result, when the CPU 31 determines that the document size detection data exceeds the threshold, the CPU 31 determines that there is a document on the document table 11 and the CPU 31 determines that the document size detection data is equal to or less than the threshold. In this case, it is determined that there is no document on the document table 11.

  On the other hand, while the original mat 12 is open on the original table 11, the original mat opening / closing detection sensor 14 is turned off, so that the white light source 17 is not turned on, but disturbance light such as a fluorescent lamp is optically transmitted from the original table 11. When entering the light receiving elements of the line image sensor 23 through the lens 22, the CPU 31 performs disturbance light calculated for each pixel of each light receiving element at any time in the same procedure as when the original mat 12 is closed. The maximum value of the data is stored in a predetermined area of the memory 36 as ambient light detection data.

  Next, the CPU 31 detects immediately before the original mat 12 is closed while the original is placed on the original table 11, and uses the ambient light detection data stored in a predetermined area of the memory 36. It is determined whether or not the ambient light detection data exceeds a threshold value for each pixel of the light receiving element. As a result, if the CPU 31 determines that the ambient light detection data exceeds the threshold, it determines that ambient light is present, and if it determines that the ambient light detection data is equal to or less than the threshold, the ambient light is detected. Judge that there is no.

  Finally, the CPU 31 detects a section in which a predetermined number of pixels determined to have a document on the document table 11 based on the document detection data and determined to have no ambient light based on the ambient light detection data. The document size in the main scanning direction is determined on the assumption that there is a document in the detected section.

  As described above, according to the image reading apparatus 10 according to the embodiment of the present invention, it is not necessary to store document detection data or disturbance light detection data in the memory 36 for each light receiving element of each RGB color. For example, as shown in FIG. 3, even when three light receiving elements of RGB 7500 pixels are used to read an image of a color document, one color is used for two areas for disturbance light component sampling and document size sampling. It suffices to have a memory of minutes (that is, 7500 × 2 areas × 1 color × image data gradation (bit)). Therefore, compared with the conventional method, it is possible to detect a document size with high accuracy even with a color document with a one-third memory amount, and to suppress an increase in memory capacity and an increase in cost.

  Further, in the image reading apparatus 10 according to the embodiment of the present invention, the maximum value for each pixel of the light reception data obtained from the light receiving elements of each RGB color is used as the document detection data, and the light reception of any color is performed. If the element reacts, it can be determined that there is a document, so that even a document whose color continuously changes can be detected accurately without erroneous detection.

DESCRIPTION OF SYMBOLS 10 Image reader 11 Document stand 12 Document mat 23 Line image sensor (generation means)
31 CPU (calculation means / determination means)
36 memory (storage means)

Claims (3)

An image reading device for detecting a size of a document placed on a document table in a main scanning direction,
Generating means for receiving reflected light from a document on the document table by a plurality of light receiving elements and generating received light data for each pixel of each light receiving element;
The light receiving data generated by the generating means is compared for each pixel of each light receiving element, the calculating means for calculating the maximum value for each pixel,
Storage means for storing a maximum value of light reception data for each pixel of each light receiving element in a predetermined area as document size detection data;
The document size in the main scanning direction is determined by determining whether or not there is a document on the document table depending on whether or not document size detection data for each pixel of the light receiving elements stored in the storage unit exceeds a threshold value. A determination means;
An image reading apparatus comprising: The generating means receives disturbance light by the light receiving elements and generates disturbance light data for each pixel of the light receiving elements when the original is placed on the document table with the original mat opened. ,
The calculation means compares the disturbance light data for each pixel of each light receiving element, calculates the maximum value for each pixel,
The storage means stores the maximum value of disturbance light data for each pixel of each light receiving element in a predetermined area as disturbance light detection data,
The determination means determines the presence or absence of ambient light depending on whether or not the ambient light detection data for each pixel of each light receiving element exceeds a threshold, determines that there is a document based on the document detection data, and the disturbance The image reading apparatus according to claim 1, wherein a document size in the main scanning direction is determined by detecting a section in which a predetermined number of pixels determined to have no disturbance light based on the light detection data. An image forming apparatus comprising the image reading apparatus according to claim 1.

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