JP2001160890A - Image reader, its document area judging method and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of judging a document area even under the influence of disturbing light. SOLUTION: In a state where a platen cover with which the surface of a platen is covered is opened and a document is not placed on the platen, this image reader detects disturbance light entering the platen, obtains the area of the diffused external light in the platen based on the result of the detection of the disturbance light, and divides an area outside of the disturbance light in the platen based on the area of the disturbance light. In a state where the platen cover is opened and the document is placed on the platen, this image reader executes reading, obtains a partial document area by each area outside of the disturbance light divided based on read information and judges the document area in the platen based on the partial document area.

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, a method for judging a document area thereof, and an image forming apparatus, and more particularly to an image reading apparatus capable of judging a document area in a platen even under the influence of disturbance light. The present invention relates to a document area determination method and an image forming apparatus.

[0002]

2. Description of the Related Art An example of a conventional image reading apparatus will be described with reference to the drawings. FIG. 12 is a perspective view of a platen portion of a conventional image reading apparatus. As shown in FIG. 12, as a device for reading a document, a document K is placed on a platen 51, and a two-dimensional document image is read by main scanning by a linear image sensor and sub-scanning by a scanning unit including a moving optical system. At this time, the platen cover 5 that covers the platen 51
In the so-called sky shot method in which the reading operation is performed with the cover 2 opened, if there is a lighting device 53 arranged on the ceiling, for example, above the platen 51, it acts as disturbance light in bright light, and in the document area detection, False detection occurs.

That is, when the original is exposed and the original area is determined from the difference in the luminance of the reflected light, the luminance of the disturbance light from a lighting fixture or the like is the same as the luminance of the reflected light reflected from the original surface. Because of the large size, an area where disturbance light enters is erroneously detected as a document area.

[0004] For this reason, conventionally, it has been required to take care to install the image forming apparatus while avoiding disturbance light, or a warning is issued to an operator to detect disturbance light and block the disturbance light. However, there is a problem in that an essential measure against disturbance light is not taken, and an accurate document area cannot be determined under the influence of disturbance light.

[0005]

As described above, in the image reading apparatus, erroneous detection of the document area is likely to occur due to disturbance light in bright light that enters the platen. In particular, when the amount of exposure light is small, such as with a xenon lamp, disturbance light in bright light entering the platen from the outside causes significant erroneous detection when determining the document area.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an image reading apparatus of a type that performs a sky shot even if disturbance light is present in bright light that enters the platen from the outside. It is an object of the present invention to provide an image reading apparatus capable of judging and detecting an original area without being affected, an original area judging method thereof, and an image forming apparatus.

[0007]

The above object can be achieved by any of the following means. That is, (1) a platen on which a document is placed, a platen cover that covers the surface of the platen, a scanning unit that scans and exposes the lower surface of the platen with a light source, and the entire area of the platen obtained by scanning of the scanning unit as image data. In the document area determining method for an image reading apparatus including a reading unit including a reading unit for reading, in a state where the platen cover is opened in advance, the light source is not turned on, and the light is incident on the platen by scanning of the scanning unit. The first image data of the platen that becomes bright light information to be obtained is acquired, disturbance light is detected from the first image data, and then a document is placed on the platen, and the platen cover is opened. Turn on the light source,
A second image data of the platen in a state where the original is placed by the scanning of the scanning unit is acquired, and the original on the platen is placed from the second image data based on the information of the detected disturbance light. A document area determination method for an image reading apparatus, comprising:

(2) A platen on which an original is placed, a platen cover that covers the surface of the platen, a scanning unit that scans and exposes the lower surface of the platen with a light source, and the entire area of the platen obtained by scanning by the scanning unit is image data. In an image reading apparatus including a reading unit configured by a reading unit that reads as
A first pre-scanning step of reading first image data, which is bright light information incident on a platen, by scanning the scanning unit without turning on the light source, placing a document on the platen, and closing the platen cover. In the opened state, the light source is turned on, and a second pre-scanning step of reading information of a document and second image data as bright light information incident on a platen by scanning of the scanning unit, and the first pre-scanning Control means for executing a document area determination step of determining a document area in which a document on the platen is placed based on the first and second image data read in the step and the second pre-scan step. An image reading apparatus, comprising:

(3) A platen on which an original is placed, a platen cover that covers the surface of the platen, a scanning unit that scans and exposes the lower surface of the platen with a light source, and the entire area of the platen obtained by scanning by the scanning unit is image data. An image reading apparatus including a reading unit including a reading unit configured to read the image as an image, and an image forming apparatus including an image forming unit configured to form an image according to image data obtained by the image reading apparatus. A first pre-scanning step of reading first image data as bright light information incident on the platen by scanning the scanning unit without turning on the light source in a state where the document is opened, and placing a document on the platen With the platen cover open,
Turning on the light source, scanning the scanning unit to read document information and second image data that becomes bright light information incident on a platen, a second prescan step, and the first prescan step and the second prescan step. A document area determining step of determining a document area where a document on the platen is placed based on the first and second image data read in the pre-scanning step; A main scanning step of acquiring image data of the original by scanning of the scanning unit in a state where is closed, and forming an image by the image forming means according to the information of the determined original area and the image data of the original. An image forming apparatus provided with control means for performing control as described above.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an image reading apparatus according to an embodiment of the present invention, a method for determining a document area thereof, and an image forming apparatus will be described. FIG. 1 is a schematic configuration diagram of an image reading device,
2 is a block diagram of an electric circuit of the image reading apparatus, FIG. 3 is a waveform of an output signal from a CCD of the reading unit, FIG. 4 is an explanatory diagram of input terminals and output terminals of the decoder, and FIG. FIG. 6 is a diagram showing a generated waveform, FIG. 6 is an explanatory diagram of a method of obtaining a disturbance light region, FIG.
FIG. 3 is an explanatory diagram of a partial original area and an original area.

As shown in FIG. 1, the image reading apparatus comprises an original placing means A, a reading means B, an operating means C, a controlling means D and the like.

The document placing means A comprises a platen 11 made of a transparent glass plate or the like on which the document K is placed, a platen cover 12 for covering the document K placed on the platen 11, and the like. The platen cover 12 is openable and closable, and is attached to the main body so as to be openable and closable in a direction perpendicular to the reading movement direction of the reading means B for reading an image by scanning.

The reading means B comprises a scanning section for scanning and exposing the platen from below with a light source, and a reading section for reading the entire area of the platen obtained by scanning of the scanning section as image data. The scanning unit includes a first mirror unit 23, a second mirror unit 26
Thus, the reading section is composed of a lens 27 and a CCD 28. The first mirror unit 23 includes a light source 21 composed of a xenon lamp for exposure and a first mirror 22. The first mirror unit 23 is attached parallel to the platen 11 and linearly movable in the left-right direction in FIG. 11 is scanned and exposed over the entire surface. The second mirror unit 26 integrally includes the second mirror 24 and the third mirror 25 and linearly moves in the same direction in the left and right directions at half the speed of the first mirror unit 23 so as to always maintain a predetermined optical path length. .
The movement of the second mirror unit 26 is parallel to the platen 11 like the first mirror unit 23.
The lower surface of the platen cover 12 exposed by the light source 21 and the image of the document K on the platen 11 are formed by a lens 27 via a first mirror 22, a second mirror 24 and a third mirror 25 onto a CCD 28 which is a linear image sensor. Image. When the scanning is completed, the first mirror unit 23 and the second mirror unit 26 return to their original positions (home positions) and wait for the next scanning.

The scanning by the reading means B has a plurality of types of scanning steps. That is, it has at least a first pre-scanning step, a second pre-scanning step, and a main scanning step. In the first prescanning step, the platen cover 12 is opened, and bright light incident on the platen 11 from outside is placed on the platen 11 in a state where the document K is not placed on the platen 11.
Read as image data. Since the document K is not placed, bright light in the entire area of the platen 11 can be read. Disturbance light that has entered the platen 11 is included in the bright light. Can be detected. In the second pre-scanning step, the platen cover 12 is opened, and the original K is placed on the platen 11 and the reflected light from the original K is incident on the platen 11 from outside in an area where the original K is not placed. The bright light is read as second image data. Thus, the bright light information outside the document area can be read together with the information on the document area. The first pre-scanning step and the second pre-scanning step are steps for obtaining image data for determining a document area on the platen 11 where a document is placed. In the main scanning step, while the platen cover 12 is closed and the document K is placed on the platen 11, scanning exposure is performed to read an image of the document as image data of the document. According to the document area information obtained by the first and second pre-scanning steps, the image data of the document read by the main scan is obtained by replacing the document area information with, for example, erasing image data outside the document area, Image processing is performed using the size information and the like, and the image is input to an image forming unit including, for example, a laser writing device, and is subjected to image exposure to form an image.

The operating means C is provided with a mode selecting means so that the first mode and the second mode can be selected.
The mode selection means 30 includes a first mode selection button 31 and a second mode selection button 32. The first mode selection button 31 selects a mode (first mode) in which the influence of disturbance light F in bright light is detected each time to determine a document area. The second mode selection button 32 stores an area of disturbance light F in bright light, and selects a mode (second mode) for determining a document area based on the stored information.
The control means D executes the selected mode according to the mode selected by the mode selection means.

Further, the control means D controls the reading means and the operating means as a whole. Further, based on the detection information of the disturbance light F, the disturbance light area Fa and the disturbance light outside area F in the platen 11 are determined.
b, a function of dividing the disturbance light outside area Fb in the platen 11, a divided partial disturbance light outside area Fb1, Fb
b2, Fb31, and Fb32 for each partial original area Ea1,
It has a function of obtaining the Ea31, a function of obtaining the document area Ea in the platen 11 based on the partial document area, and a function of storing information obtained by dividing the disturbance light outside area Fb.

FIG. 2 is a block diagram showing an electric circuit for obtaining a disturbance light area Fa, an original area Ea, and the like. In the figure, G1
Is an AND gate of signals VV3 and HV31, G2 is an AND gate of signals VV1 and HV, G3 is an AND gate of VV2 and HV, G5 is an AND gate of HV32 and VV3,
G4 is an OR gate of G1, G2, and G3. The first selector 41 and the second selector 43 are selectors that switch to the A terminal or the B terminal according to a sampling signal. The first determination circuit 42 determines (specifies) the coordinates of the upper left point and the lower right point of the diagonal line of the disturbance light area and the partial document area, and the second determination circuit 44 determines the first determination circuit 4.
The upper left corner of the diagonal line of the other partial document area not determined in step 2,
It is a hardware conceptual block for determining (identifying) the lower right point coordinates. The first and second determination circuits 42 and 44 output the image signal V, the main scanning synchronization signal HV, the sub-scanning synchronization signal VV,
Enter two types of settable threshold values TH1 and TH2,
As a result of the calculation, the upper left point (X1min, Y1) and the lower right point (X2max,
Y2) is determined (specified). Further, the arithmetic circuit 45 is a hardware conceptual block for calculating the disturbance light area Fa and the document area Ea.

FIG. 4 shows a decoder 46 having a plurality of input terminals and a plurality of output terminals. When a signal is added to a certain combination of input terminals, one decoder corresponding to the combination is provided. A signal appears at the output terminal. As input terminals, signals HV, VV, diagonal upper left point coordinates and diagonal lower right point coordinates, and as output terminals,
The signals HV, VV, VV1, VV2, VV3, HV31,
There is HV32.

FIG. 5 shows output waveforms at the output terminals of the decoder 46 shown in FIG.

In the present invention, an area where disturbance light exists in the entire area of the platen is detected (first prescanning step), and the area where the detected disturbance light exists is approximated as a rectangular disturbance light area. Detecting a partial document area in a partial disturbance light outside area excluding the disturbance light area where the disturbance light exists from information on the entire area of the platen on which the document is placed (second pre-scanning step); The document area is determined by estimating the entire document area from the detected partial document area.

The method of determining the document area will now be described with reference to FIG.
, FIG. 8, FIG. 10, and FIG.

First, the first mode selection button 31 is pressed. Thereafter, the platen cover 12 covering the surface of the platen 11 shown in FIG. 1 is opened. Next, the first pre-scan is performed by the reading unit B in a state where the document K is not on the platen 11. In the first pre-scan, the light source 21 is turned off and scanning is performed, and the CCD 28 obtains bright light information of the entire area of the platen including disturbance light as first image data (flow F0).
1).

Next, the sampling signal shown in FIG. 2 is output, and the first selector 41 and the second selector 43
Set to the side. Then, a signal of image data from the CCD 28 is used to determine (specify) a disturbance light area using the first determination circuit 42 (flow F02).

A method for obtaining the disturbance light area will be specifically described. FIG. 3A shows the relationship between the image data and the threshold value. Constant threshold TH1 for level
The white level is higher than TH1 and the lower level is black. Now, a curve at a point where the scanning is changed from black to white first after scanning from the left (hereinafter referred to as a rising point) is stored. Conversely, a point at which the color changes from white to black (hereinafter, a falling point) is detected, and a distance L (the number of pixels) from the rising point to the falling point is calculated. A second threshold value TH2 (for example, two pixels) is provided for the distance L (the number of pixels) to eliminate noise. The detected value is compared with the second threshold value TH2, and when L is larger than TH2, the rising point is determined as a candidate point. For example, FIG.
If the distance (the number of pixels) is short due to the influence of image noise or the like as shown in FIG. If the image data is equal to or greater than a certain threshold value (TH1), it is determined that the image data is white data, and the other data is black data.

As described above, when the continuous length of the white data exceeds a certain threshold value (TH2) for each scanning line, it is considered that disturbance light exists on this scanning line. White data is TH2
The first point that follows is regarded as the beginning of disturbance light, and the starting point X
Let it be 1. The last point where the white data continues for TH2 or more is regarded as the end of the disturbance light, and is set as the end point X2. From the effective points X1 and X2 obtained from each scanning line, the minimum value X1 of X1
The maximum value X2max of min and X2 is obtained. Further, with respect to the sub-scanning direction, Y
The coordinate Y1 is a start point of the disturbance light, and the Y coordinate Y2 of the scanning line at which the effective point is finally generated is an end point of the disturbance light.
From the above, the disturbance light area Fa is defined by the coordinates (X1min, Y1) of the diagonal upper left point of the disturbance light and the coordinates (X2max, Y2) of the diagonal lower right point shown in FIG. 6 are the end points of the maximum frame of the disturbance light. Is approximated as a disturbance light region.

In the above-described embodiment, the disturbance light
As described above, the case where the platen 11 is located substantially at the center has been described, but the same applies to other positions. FIG.
FIG. 4 is a diagram illustrating an example of a disturbance light area and a disturbance light outside area. FIG.
0 (a) is the disturbance light area Fa and the partial disturbance light outer areas Fb31 and Fb when the disturbance light enters the belt shape parallel to the sub-scanning direction.
FIG. 10B shows how to divide the disturbance light into the disturbance light area Fa and the partial disturbance light outside areas Fb1 and Fb2 when the disturbance light enters a strip parallel to the main scanning direction. Further, FIG. 10C shows how the disturbance light is divided into the disturbance light area Fa and the partial disturbance light outer areas Fb1 and Fb31 when the disturbance light enters the end point of the maximum frame of the platen 11 as shown in FIG. Is represented.

Next, the disturbance light outside region Fb is defined as 4 shown in FIG.
Area Fb1, Fb31, Fb32, F
b2 (flow F03).

Fb1 is a portion above the upper end of the disturbance light region Fa, Fb2 is a portion below the lower end of the disturbance light region Fa, Fb31 is a left side of the left end of the disturbance light region Fa, and
This is a portion excluding b1 and Fb2. Fb32 is a portion on the right side of the right end of the disturbance light area Fa, excluding Fb1 and Fb2.

Next, the platen cover 12 is opened, and the document K is placed on the platen 11 (FIG. 1). Thereafter, the light source 21 of the xenon lamp is turned on by the reading means B, and scanning is performed in the second pre-scanning by the CCD 28.
Bright light including the reflected light of the document K and the disturbance light F is obtained as the second image data (flow F04).

Next, as shown in FIG. 8, for each of the partial disturbance light outside regions Fb1 and Fb31, a partial original region E
a1 and Ea31 are obtained. First, the decoder 46 shown in FIG.
From the horizontal synchronization signal HV, the vertical synchronization signal VV, the coordinates (X1min, Y1) of the diagonal upper left point of the disturbance light, and the coordinates (X2max, Y2) of the diagonal lower right point, the signals HV, V
V, VV1, VV2, VV3, HV31 and HV32 are generated, respectively, and the signals shown in FIG. 5 are generated. Each generated signal is input to the electric circuit block shown in FIG. In the regions Fb1, Fb2, and Fb31 outside the partial disturbance light,
Using the first determination circuit 42, the partial disturbance light outside region Fb32
Then, the second determination circuit 44 is used. The partial document area is set to a partial document area Ea1 in the same manner as the method of obtaining the disturbance light area, and the diagonal upper left point coordinate (X
1 min, Y1) and lower right point coordinates (X2max, Y2). Also, as the partial original document area Ea31, the coordinates of the upper left corner of the diagonal (X3min, Y3) and the coordinates of the lower right corner of the diagonal (X4max, Y4) are obtained as the end points of the maximum frame (flow F).
05).

Further, as shown in FIG. 8, a rectangular shape indicated by Ea including the partial document area is obtained from the two partial document areas Ea1 and Ea31. This rectangular shape is estimated by calculating from the maximum value and the minimum value of the diagonal coordinates of the document areas Ea1 and Ea31, and the diagonal coordinates (X1min, Y1) and (X2max, Y4) are set as end points of the diagonal. It has a rectangular shape. The document K
(The flow F06). Thus, a document area is obtained.

Next, a method of temporarily storing the disturbance light area will be described. First, the second mode button 32 is pressed.
In the first time, the above-mentioned flow F01 to flow F03 are performed. Here, the areas outside the partial disturbance light such as Fb1 and Fb2 are stored. Subsequently, the processing from flow F04 to flow F06 is performed. From the second time, since the area outside the partial disturbance light is stored, the flow F01 to the flow F03 are not performed, and the flow F04 to the flow F06 are repeated. Thus, the document area is obtained.

In the present invention, instead of storing the disturbance light area, information on the disturbance light outside area (area opposite to the disturbance light area) obtained from the information on the disturbance light area is stored. This simplifies the flow. In the claims, the recording of the disturbance light area is expressed, but the information of the disturbance light area and the information of the disturbance light area are substantially modified examples and are treated as the same. However, the information itself of the disturbance light area may be stored, and after the second time, only the flow F01 and the flow F02 may be excluded, and the flow F03 and the subsequent may be repeated.

Here, the difference in the detection of the document area due to the difference between the document position and the disturbance light position will be described with reference to an embodiment of the present invention and a comparative example. FIG. 11 is an explanatory diagram for specifying a document area according to the embodiment of the present invention and the comparative example. FIG. 11A shows the positional relationship between the reflected light of the document K on the platen 11 and the disturbance light F.
FIG. 11B shows detection of a document area according to the embodiment of the present invention, and FIG. 11C shows a comparative example. In the comparative example, the first pre-scanning step was not performed, but only the second pre-scanning step was performed.
The white data area was detected from the information on the entire area of the platen to determine the document area.

In the model 1, the original area Ea1A can be accurately detected in the embodiment, but the original area is erroneously detected as Ea2A in the comparative example. In model 2,
In the embodiment, an accurate document area Ea1B can be detected. In the comparative example, as shown in FIG. 11, the document area is erroneously detected as Ea2B larger than the document K.

Although the embodiment has been described with respect to the image reading mechanism in which the optical system moves and performs scanning, the present invention may employ a system in which the optical system is fixed and the platen moves.

As described above, in the image reading apparatus of the sky shot type, it is possible to determine and detect the document area even under the influence of disturbance light.

An image forming apparatus according to the present invention is an image forming apparatus to which the above-described image reading apparatus is applied. The image forming apparatus has the above-described image forming apparatus, and applies image data obtained by the image reading apparatus. Therefore, it has an image forming means for forming an image. Further, with the platen cover open, the light source is not turned on, and the scanning unit scans to read first image data as bright light information incident on the platen. A second pre-scanning step of turning on the light source while the platen cover is open, reading the information of the document and the second image data as bright light information incident on the platen by scanning of the scanning unit, and Based on the first and second image data read in the first pre-scanning step and the second pre-scanning step, a document area determining step of determining a document area on the platen where the document is placed is executed, and the document is determined. The main scanning process of acquiring image data of the original by scanning the scanning unit with the platen closed with the platen closed is executed, and the information of the determined original area and the original And a control means for forming an image by the image forming means in accordance with the image data.

The second image data is composed of a disturbance light area where disturbance light exists and image data of a disturbance light outside area where there is no disturbance light. The original area is determined based on the image data of the disturbance light outside area. .

As described above, in the image forming apparatus to which the image reading apparatus of the sky shot type is applied, the original area can be determined and detected even under the influence of disturbance light. Further, it can be preferably used for processing of document size detection, document frame erasing, and the like based on the obtained document area information.

[0041]

According to the above configuration, the following effects can be obtained.

According to the first aspect of the present invention, based on the information of the detected disturbance light,
Since the document area where the document on the platen is placed is determined from the second image data, in the method of performing a sky shot, even if disturbance light exists in bright light entering the platen from the outside, it is not affected. The original area can be determined and detected.

According to the document area determining method of the image reading apparatus of the present invention, the document area is determined based on the image data of the area outside the disturbance light, so that the determination of the document area can be simplified.

According to the image reading apparatus of the third aspect,
With the platen cover open, the light source is not turned on, and the scanning unit scans to read first image data as bright light information incident on the platen. A second pre-scanning step of turning on the light source with the platen cover open to read the document information and the second image data as bright light information incident on the platen by scanning of the scanning unit; and a first press. Since there is provided control means for executing a document area determination step of determining a document area where a document on the platen is placed based on the first and second image data read in the can step and the second pre-scan step. In an image reading apparatus that performs a sky shot, even if disturbance light is present in bright light that enters the platen from the outside, the document area is determined without being affected. It can be detected.

According to the image reading apparatus of the fourth aspect,
In the document area determination step, disturbance light in bright light is detected from the first image data, information on the detected disturbance light area and a second sheet obtained in a state where the document obtained in the second pre-scanning step is placed. Since the document area is determined based on the image data, the document area can be determined and detected without being affected by disturbance light during bright light.

According to the image reading apparatus of the fifth aspect,
Since the document area is determined based on the disturbance light information in the disturbance light outside area excluding the disturbance light area, the document area can be easily determined.

According to the image reading apparatus of the sixth aspect,
In the determination of the document area, the partial document area in the area outside the disturbance light is detected, and the document area of the entire document is determined from the information of the partial document area. Therefore, the determination of the document area can be simplified.

According to the image reading device of the seventh aspect,
Since the disturbance light region is a region approximated to a rectangular shape including a portion where the disturbance light exists, the disturbance light region can be easily determined.

According to the image reading apparatus of the eighth aspect,
Since the rectangular shape is represented by diagonal end point coordinates, the disturbance light area can be easily handled.

According to the image reading apparatus of the ninth aspect,
Since the light source is a xenon lamp, stable reading can be performed with little change over time of the light source.

According to the image reading apparatus of the tenth aspect, the first mode in which the disturbance light area is detected each time to determine the document area and the information of the disturbance light area are temporarily stored, and the correction is performed based on the storage. Since the second mode for determining the document area is provided, the time can be shortened and the use mode can be appropriately selected.

According to the image forming apparatus of the present invention, the light source is not turned on with the platen cover open,
A first pre-scanning step of reading first image data as bright light information incident on the platen by scanning of the scanning unit, placing a document on the platen, turning on the light source with the platen cover open, The second is the information of the document and the bright light information incident on the platen by the scanning of the scanning unit.
Based on the second pre-scanning step of reading image data, and the first and second image data read by the first pre-scanning step and the second pre-scanning step, a document area on the platen on which a document is placed is determined. A document area determination step is performed, and a main scanning step of obtaining image data of the document by scanning the scanning unit with the document placed and the platen closed is performed. Control means for controlling the image forming means to form an image in accordance with the image data, so that in the method of performing a sky shot, even if disturbance light is present in bright light entering the platen from the outside, it is affected. The document area can be determined and detected without the need.

According to the image forming apparatus of the twelfth aspect, since the document area is determined based on the image data in the area outside the disturbance light, the determination of the document area can be simplified.

According to the image forming apparatus of the thirteenth aspect, since the information of the document area is used for erasing outside the document area, it can be preferably used for erasing processing outside the document area.

According to the image forming apparatus of the present invention, since the information of the document area is used for the document size information, it can be preferably used for processing the document size information.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image reading apparatus.

FIG. 2 is an electric circuit block diagram of the image reading apparatus.

FIG. 3 is a waveform of an output signal from a CCD of a reading unit.

FIG. 4 is an explanatory diagram of an input terminal and an output terminal of the decoder.

FIG. 5 is a diagram showing a generated waveform of an output signal in a decoder.

FIG. 6 is an explanatory diagram of how to obtain a disturbance light area.

FIG. 7 is an explanatory diagram of a disturbance light region and a disturbance light outside region.

FIG. 8 is an explanatory diagram of a partial document area and a document area.

FIG. 9 is a flowchart for obtaining a document area.

FIG. 10 is a diagram illustrating an example of a disturbance light region and a disturbance light outside region.

FIG. 11 is a diagram illustrating a specific example of a document area according to an embodiment of the present invention and a comparative example.

FIG. 12 is a perspective view of a platen portion in a conventional image reading apparatus.

[Explanation of symbols]

 11 Platen 12 Platen Cover 21 Light Source K Document F Disturbance Light Ea Document Area Eb Outside Document Area Fa Disturbance Light Area Fb Disturbance Light Outside Area

Claims (14)

[Claims] 1. A platen on which a document is placed, a platen cover that covers the surface of the platen, a scanning unit that scans and exposes a lower surface of the platen with a light source, and the entire area of the platen obtained by scanning by the scanning unit as image data. In the document area determining method for an image reading apparatus including a reading unit including a reading unit for reading, in a state where the platen cover is opened in advance, the light source is not turned on, and the light is incident on the platen by scanning of the scanning unit. The first image data of the platen that becomes bright light information to be obtained is acquired, disturbance light is detected from the first image data, and then a document is placed on the platen, and the platen cover is opened. Illuminating the light source to obtain second image data of a platen in a state where a document is placed by scanning by the scanning unit, and based on information of the detected disturbance light, And determining a document area in which the document on the platen is placed from the second image data. 2. The image data according to claim 1, wherein the second image data includes a disturbance light area where disturbance light exists and image data of a disturbance light outside area where no disturbance light exists. The method according to claim 1, wherein the determination is performed. 3. A platen on which a document is placed, a platen cover that covers the surface of the platen, a scanning unit that scans and exposes a lower surface of the platen with a light source, and the entire area of the platen obtained by scanning by the scanning unit as image data. In an image reading apparatus provided with a reading unit constituted by a reading unit for reading, in a state where the platen cover is opened, the light source is not turned on, and scanning by the scanning unit causes bright light information to enter the platen. A first pre-scanning step of reading first image data, placing a document on the platen, turning on the light source with the platen cover open, and scanning information of the document and platen by scanning of the scanning unit. A second pre-scan step of reading second image data that is bright light information incident on the first and second pre-scan steps; 2. A control unit for executing a document area determination step of determining a document area where a document on the platen is placed based on the first and second image data read in the two pre-scan steps. Image reading device. 4. In the document area determination step, disturbance light in bright light incident on a platen is detected from first image data read in the first pre-scan step, and the detected disturbance light area is detected. 4. The image reading apparatus according to claim 3, wherein the document area is determined based on the information of the document and second image data obtained in a state where the document obtained by the second pre-scanning step is placed. 5. 5. The method according to claim 2, wherein the second information is based on information on the disturbance light.
Image data is divided into a disturbance light area affected by disturbance light and a disturbance light outside area not affected by disturbance light, and a document area is determined based on the disturbance light outside area excluding the disturbance light area. The image reading device according to claim 4, wherein 6. The method according to claim 5, wherein the determination of the document area includes detecting a partial document area outside the disturbance light area, and determining a document area of the entire document from information on the partial document area. The image reading device according to claim 1. 7. The image reading apparatus according to claim 4, wherein the disturbance light region is a region approximated to a rectangular shape including a portion where the disturbance light exists. 8. The image reading apparatus according to claim 7, wherein the rectangular shape is represented by diagonal end point coordinates. 9. The image reading apparatus according to claim 3, wherein the light source is a xenon lamp. 10. A first mode for determining a document area by detecting a disturbance light area each time, and a second mode for temporarily storing information of a disturbance light area and correcting the document area based on the storage. The image reading apparatus according to claim 3, further comprising: 11. A platen on which a document is placed, a platen cover that covers the surface of the platen, a scanning unit that scans and exposes the lower surface of the platen with a light source, and the entire area of the platen obtained by scanning the scanning unit as image data. An image reading apparatus including a reading unit including a reading unit to read, and an image forming apparatus including an image forming unit configured to form an image in accordance with image data obtained by the image reading apparatus; In the opened state, the light source is not turned on, and the scanning unit scans to read first image data, which is bright light information incident on the platen. The first pre-scanning step includes placing a document on the platen. , With the platen cover open,
Turning on the light source, scanning the scanning unit to read document information and second image data that becomes bright light information incident on a platen, a second prescan step, and the first prescan step and the second prescan step. A document area determining step of determining a document area where a document on the platen is placed based on the first and second image data read in the pre-scanning step; A main scanning step of acquiring image data of the original by scanning of the scanning unit with the scanner closed, and forming an image by the image forming means according to the information of the determined original area and the image data of the original. An image forming apparatus provided with control means for performing control as described above. 12. The second image data includes a disturbance light area where disturbance light exists and image data of a disturbance light outside area where no disturbance light exists, and the original area is determined by the image data of the disturbance light outside area. The method according to claim 1, wherein the determination is made.
2. The image forming apparatus according to 1. 13. The image forming apparatus according to claim 11, wherein the information of the document area is used for erasing outside the document area. 14. The image forming apparatus according to claim 11, wherein the information of the document area is used for document size information.