JP2000151893A - Original size detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the original size detector that accurately discriminates and detects edges of an original even when there are more or less points read by black pixels such as characters or dust around edges of the original. SOLUTION: A CCD image sensor 16 as an imaging device reads one line of an image on an original 12 placed on an original placing platen 11. Then pixels whose level changes from a black level to a white level are discriminated to be an edge 12a in a main scanning direction P1 of the original 12 when the number of pixels whose level is read to be a black level among several pixels changed from pixels read to have a black level into pixels read to have a white level is smaller than a prescribed number in the read data by a control means. In this case, a criterion of the number of black pixels p1 to discriminate the edge 12a of the original 12 is in a range of 6-25%.

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 in a digital copying machine or the like.

[0002]

2. Description of the Related Art A conventional document size detection apparatus of this type includes a light source for irradiating a document placed on a document table with light, and an image pickup device for reading an image on the document based on light reflected from the document. 2. Description of the Related Art There is known a document reading apparatus including a device and configured to detect an edge of a document in a main scanning direction.

In this conventional apparatus, when the original mat opening / closing switch is turned off, the light source is moved to a position immediately below the original, and when the original mat opening / closing switch is turned on, the light source is turned on at the same time as the original mat opening / closing switch is turned on. The image of 1
Lines are read. At this time, a portion having no document is read with black pixels, and a portion corresponding to the document is read with white pixels. Then, in this read image data, a pixel that changes from black to white is detected, and when several pixels are continuously detected as white, the pixel that changes from black to white is determined to be the edge of the document. It was like.

[0004]

However, in this conventional document size detection apparatus, unless several pixels are continuously detected as white, the document is not recognized as an edge of the document.
There is a problem in that when there are characters, dust, and the like near the edge of the document, and these are read with black pixels, the edge of the document is erroneously determined.

[0005] The present invention has been made by paying attention to such problems existing in the prior art. The purpose of the document size detection is to accurately detect and detect the edge of the document even if there are some points that are read with black pixels such as characters and dust near the edge of the document. It is to provide a device.

[0006]

According to the first aspect of the present invention, there is provided a light source for irradiating light on a document placed on a document table, and a light reflected from the document. A document reading device that includes an image sensor that reads an image on a document based on a document, and detects an edge of the document in the main scanning direction. In the image data, from a pixel read as black to a pixel read as white, and from several pixels, when the number of pixels read as black is smaller than a predetermined value, the pixel changes from black to white. A control means for determining a pixel as an edge of a document is provided.

According to a second aspect of the present invention, in the document size detecting apparatus according to the first aspect, the control means changes from a pixel read as black to a pixel read as white to several pixels. When the number of pixels read as black is less than 6 to 25% of the number of pixels read as white, the pixel that has changed from black to white is determined to be the edge of the document. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, in a document size detecting device using the document reading device of this embodiment, a document placing table 11 is formed of a transparent plate such as glass, and a document 12 is placed on an upper surface thereof. I have. A document mat 13 is provided on the document table 11 so as to be openable and closable. After the document 12 is placed on the document table 11, the document mat 13 is closed. An original mat opening / closing switch 14 is provided near one side of the original placing table 11.
The open / close switch 14 is turned off or on.

A lamp unit 15 as a light source is disposed below the document table 11 so as to be movable in a sub-scanning direction P2 perpendicular to the main scanning direction P1, and irradiates the document 12 on the document table 11 with light. It is supposed to. A CCD image sensor 16 as an image sensor is provided below the document table 11 so as to be movable in a sub-operation direction P2 via a moving table (not shown). To read.

A first reflection type sensor 17 and a second reflection type sensor 18 are arranged on the movable table so as to be adjacent to the CCD image sensor 16. When reading an image on the document 12, the reflection type sensor 1
7 and 18, the edge 1 of the document 12 on the side of the sub-scanning direction P2.
2b is detected.

Next, the circuit configuration of the document size detecting device configured as described above will be described. As shown in FIG. 2, a central processing unit (CPU) 21 controls the operation of each unit of the document size detecting device. Read only memory (RO
M) 22 stores various programs necessary for the operation of the document size detecting device. The random access memory (RAM) 23 includes a data storage unit 23a,
It temporarily stores the read image data read by the image sensor 16 and various data obtained by executing the control program. And the CPU 21 and the ROM 2
2 and the RAM 23 constitute control means.

The CPU 21 reads the image data read from the CCD image sensor 16, the first reflection type sensor 17,
Second reflective sensor 18 and original mat open / close switch 14
The detection signal from is input. Further, the CPU 21 outputs an operation control signal to the lamp unit 15 and a lamp unit moving mechanism 24 for moving the lamp unit 15.

Next, the detecting operation of the document size detecting device constructed as described above will be described with reference to the flowchart shown in FIG. This flowchart is based on the ROM
22 based on the control program stored in the
It proceeds under the control of U21.

In this document size detecting device,
When the document mat 13 is opened to place the document 12 on the document table 11, the document mat open / close switch 14 is turned off (S1), and the lamp unit 15 is moved by the moving mechanism 24.
Is moved to the reading position corresponding to the original 12 (S
2). Thereafter, when the original 12 is placed on the original placing table 11 and the original mat 13 is closed, the original mat open / close switch 14 is turned on (S3).

In this state, the lamp unit is turned on (S4), and the original image is
The upper image is read for one line (S5). At this time, as shown in FIG. 4, a portion without the document 12 is read by a black pixel p1, and a portion corresponding to the document 12 is read by a white pixel p2. After the read image data is subjected to shading (SHD) correction and gamma (γ) correction, the data storage unit 23a of the RAM 23
Is stored.

Thereafter, in the read image data stored in the data storage unit 23a, a boundary b1 that changes from a black pixel p1 to a white pixel p2 is detected. In addition, in a few pixels s1 (8 pixels in FIG. 4) from the boundary b1,
The number of black pixels p1 and the number of white pixels p2 are detected, and it is determined whether the number of black pixels p1 is less than 6 to 25% of the number of white pixels p2 (S6). When the number of black pixels p1 is less than 6 to 25% of the number of white pixels p2, the white pixels p at the boundary b1 where black has changed to white
2a is determined as the edge 12a of the document 12 on the side of the main scanning direction P1 (S7).

Thus, the operation of detecting the edge 12a of the document 12 on the side of the main scanning direction P1 is completed. The size of the document 12 is determined based on the detection result of the edge 12a in the main scanning direction P1 and the detection result of the edge 12b in the sub-scanning direction P2 output from the reflection sensors 17 and 18. Is done.

The effects exerted by the above embodiment will be described below. In the document size detection device of this embodiment, in the read image data read by the CCD image sensor 16 as an image sensor, the pixel p read as black
When the number of pixels p1 read as black is smaller than a predetermined value during a few pixels s1 after changing from 1 to a pixel p2 read as white, the pixel p2a changed from black to white is placed in the document 12.
Is determined as the edge 12a.

For this reason, even if there is a character or dust near the edge 12a of the document 12, and it is read by the black pixel p1 in the read image data, the edge 1
2a can be accurately determined without error and detected.

In the document size detection apparatus of this embodiment, the number of pixels p1 read as black changes from pixel p1 read as black to pixel p2 read as white and s1 for several pixels. Is smaller than 6 to 25% of the number of pixels p2 read as white, the pixel p2a changed from black to white is determined to be the edge 12a of the document 12.

For this reason, the number of pixels p1 read as black is compared with the number of pixels p2 read as white, and
By determining whether it is less than 5%, the original 12
Can be accurately detected.

The above embodiment can be embodied with the following modifications. In the above-described embodiment, the reference value for determining the number of black pixels p1 in determining the edge 12a of the document 12 is, for example, 10 to 20% within the range of 6 to 25% of the embodiment.
Etc. or outside the range of 6 to 25%.

With this configuration, the accuracy of discriminating the edge 12a of the document 12 can be determined appropriately according to the purpose. In the above-described embodiment, the number of pixels read as black is changed to a predetermined value within a certain range of pixels between 2 and several tens of pixels by changing from pixels read as black to pixels read as white. When the number of pixels is smaller than that, the pixel that has changed from black to white is determined to be the edge of the document.

In the case of such a configuration, the accuracy of discriminating the edge 12a of the document 12 can be appropriately determined according to the purpose. Further, a technical idea grasped from the embodiment will be described below.

The image pickup device is a charge-coupled device (CC)
3. The document size detecting device according to claim 1, wherein the device is an image sensor. With this configuration, the edge of the document can be easily and accurately determined and detected.

The document size detecting device according to claim 1 or 2, wherein the reflection type sensor detects the edge of the document in the sub-scanning direction when reading an image on the document. .

With this configuration, both edges of the document in the main scanning direction and the sub-scanning direction can be accurately discriminated and detected without error. Main scanning of a document using a document reading device including a light source that irradiates light on the document placed on the document table and an image sensor that reads an image on the document based on reflected light from the document; In the original size detecting method for detecting an edge in the direction, the control unit changes the number of pixels in the read image data read by the image sensor from black read pixels to white read pixels. A document size detection method in which when the number of pixels read as black between pixels is smaller than a predetermined value, a pixel that has changed from black to white is determined as an edge of the document.

According to this method, the edge of the document can be easily and accurately determined and detected.

[0029]

The present invention is configured as described above, and has the following effects. According to the document size detecting device of the first aspect of the present invention, even if there is a character or dust near the edge of the document and it is read with black pixels in the read image data, The edge can be accurately determined without error and detected.

According to the document size detecting apparatus of the second aspect, in addition to the effect of the first aspect, the number of pixels read as black is reduced by the number of pixels read as white. In comparison, by determining whether it is less than 6 to 25%, it is possible to more reliably detect the edge of the document.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a document size detection device according to the present invention.

FIG. 2 is a block diagram illustrating a circuit configuration of a document size detection device.

FIG. 3 is a flowchart illustrating a detection operation of the document size detection device.

FIG. 4 is an explanatory diagram showing states of pixels of read image data.

[Explanation of symbols]

Reference numeral 11: document table, 12: document, 12a: edge, 15 ...
Lamp unit as a light source, 16: CCD image sensor as an imaging device, 21: CP constituting control means
U, 22: ROM constituting control means, 23: RAM constituting control means, P1: main scanning direction, p1: black pixel, p2: white pixel, p2a: boundary pixel.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Osunori Okubo 1-2-28 Tamazo, Chuo-ku, Osaka-shi, Mita Industrial Co., Ltd. F-term (reference) 2H012 CA07 5C062 AA05 AB17 AC63 AC67 AF10 BA04 5C072 AA01 BA13 LA01 RA04 XA01

Claims (2)

[Claims] An original reading device comprising: a light source for irradiating light on an original placed on an original mounting table; and an image sensor for reading an image on the original based on reflected light from the original. In a document size detection device configured to detect an edge of a document in the main scanning direction, in a read image data read by the image sensor, a pixel that is read as black changes to a pixel that is read as white. An original size detecting device provided with control means for judging a pixel changed from black to white as an edge of the original when the number of pixels read as black is smaller than a predetermined value between several pixels. 2. The method according to claim 1, wherein the control unit changes from a pixel read as black to a pixel read as white and sets the number of pixels read as black to the number of pixels read as white between several pixels. 2. The document size detecting device according to claim 1, wherein when the value is less than 6% to 25%, a pixel changed from black to white is determined as an edge of the document.