JP2000138798A - Document size detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a document size detecting device, which can accurately discriminate and detect an end edge of a document, even in an environment where disturbing light exerts influence. SOLUTION: While a light source 15 is turned off and a light source 15 is turned on, a document 12 mounted on a document mount table 11 is read by an image pickup element by the time when a document mat 13 is completely closed after a document mat opening/closing switch 14 is turned on. The effects of the disturbing light are removed by calculating the differences between both pieces of read image data and an end edge 12a of the document 12 on the side of a horizontal scanning direction P1 is discriminated according to the processed image data. Furthermore, an end edge 12b of the document 12 on the side of the vertical scanning direction P2 is discriminated with the detection signals from a 1st reflection type sensor 17 and a 2nd reflection type sensor 18. Thus, the size of the document 12 is detected according to the discrimination of both the edges 12a and 12b of the document.

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 has been known an apparatus which detects an original size by using an original reading apparatus having an element.

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 the light source is turned on at the same time as the original mat opening / closing switch is turned on. Next, until the document mat is completely closed, one line of the image on the document is read by the image sensor. Then, in the read image data, an edge of the document is determined by detecting a boundary at which a black pixel corresponding to a portion having no document is changed to a white pixel corresponding to the document. .

[0004]

However, in this conventional document size detecting device, the image on the document is read before the document mat is completely closed. In this case, the light from the lighting fixture is read as disturbance light by white pixels. For this reason, in the read image data, a white pixel corresponding to disturbance light is regarded as a white pixel corresponding to the original,
There is a problem that 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. It is an object of the present invention to provide a document size detecting device capable of accurately determining and detecting an edge of a document even in an environment affected by disturbance light.

[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. The document mat is completely closed after the document mat open / close switch is turned on in a document size detection device that detects the size of the document using a document reading device having an image sensor that reads an image on the document based on the document. Until the light source is turned off and the light source is turned on, the control unit that causes the image sensor to read the original and determines a difference between the read image data and the edge of the original is determined. It 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 performs black-and-white inversion processing on either one of the read-out state and the turn-on state, and inverts the read-out image data. By combining the image data and the other read image data, the difference between the two read image data is obtained.

[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 first data storage unit 23a and a second data storage unit 23b, and reads image data read by the CCD image sensor 16 and various data obtained by executing a control program. Etc. are temporarily stored. The CPU 21, the ROM 22, and the RAM 23 constitute a control unit.

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).

At this time, until the document mat 13 is completely closed, one line of the image on the document 12 is read by the CCD image sensor 16 with the lamp unit 15 turned off (S4). In this case, since the lamp unit 15 is off, as shown in FIG. 4A, the entire read image data is black pixels. When a lighting device such as a fluorescent lamp is disposed immediately above the document table 11, the light of the lighting device is read as disturbance light in white pixels in the read image data. Then, after the read image data is subjected to shading (SHD) correction and gamma (γ) correction, the read image data is subjected to black-and-white inversion processing as shown in FIG. (S5).

Subsequently, with the lamp unit 15 turned on, the CCD image sensor 16 reads one line of the image on the document 12 (S6). in this case,
As shown in FIG. 4C, original 1
In the portion corresponding to 2, white and black pixels are mixed up, and in the portion without the document 12, black pixels appear. At this time, since the document mat 13 is not completely closed, the light of the illumination device is read as disturbance light in the read image data by white pixels. The read image data is SH
After the D correction and the γ correction, they are stored in the second data storage unit 23b of the RAM 23 (S7).

In this state, the image data stored in the first data storage unit 23a of the RAM 23 and the image data stored in the second data storage unit 23b are combined and stored in the first data storage unit 23a. (S8). This allows
This means that the difference between the read image data in the light-off state and the read image data in the light-on state has been obtained. As shown in FIG. 4D, a white pixel portion due to the influence of disturbance light is removed.

Further, based on the composite image data stored in the first data storage section 23a, a boundary at which a black pixel corresponding to a portion having no document 12 and a white pixel corresponding to the document 12 are detected. The edge 12a of the document 12 on the main scanning direction P1 side is determined. Also, the first reflection type sensor 1
The edge 12b of the document 12 on the side of the sub-scanning direction P2 is determined based on the detection signals from the sensor 7 and the second reflective sensor 18.
Then, the size of the document 12 is detected based on the determination of the edges 12a and 12b of the document 12 (S9).

Thereafter, the lamp unit 15 is turned off (S10), and the lamp unit 15 is returned to the home position by the moving mechanism 24 (S11).
Thus, the operation of detecting the size of the document 12 is completed.

The effects exerted by the above embodiment will be described below. In the document size detection device of this embodiment, the lamp unit 15 as a light source is turned off and turned on after the document mat open / close switch 14 is turned on and before the document mat 13 is completely closed. In this state, the original placing table 11 is
The reading of the original 12 placed thereon is performed. Then, with the difference between the two read image data being taken, the original 12
Is determined.

For this reason, even if the influence of disturbance light is read by white pixels in the read image data in the lighting state of the lamp unit 15, the read image data in the unlit state and the read image data in the lit state are read. When taking the difference, the influence of the disturbance light is removed. For this reason, even in an environment such as a lighting fixture which is affected by disturbance light, the edge 12a of the document 12 can be accurately determined and detected.

In the document size detecting apparatus of this embodiment, either one of the read image data in the light-off state and the light-on state is subjected to black-and-white inversion processing, and the inverted image data is combined with the other read image data. Thus, the difference between the two read image data can be obtained.

Therefore, the difference between the read image data in the light-off state and the read image data in the light-on state can be easily obtained, and the influence of disturbance light can be reliably removed. This embodiment can be embodied with the following modifications.

Contrary to the above embodiment, the read image data in the lighting state is subjected to black-and-white inversion processing, the inverted image data is combined with the read image data in the unlit state, and the difference between the two read image data is calculated. To take.

Even in the case of such a configuration, the edge of the document can be accurately determined and detected based on the difference between the two read image data. In the above embodiment, the moving direction of the lamp unit 15 is the main scanning direction P1 of the document 12, and the moving direction of the CCD image sensor 16 is the sub-operation direction P2.

In such a configuration, the edge 12b on the sub-scanning direction P2 side can be determined by the CCD image sensor 16. Further, a technical idea grasped from the embodiment will be described below.

[0027] Further, a reflection type sensor for irradiating the original with light and detecting the reflected light thereof is provided, and an edge different from the edge of the original is determined. Document size detection device described in the above.

With such a configuration, both edges of the document can be determined, and the size of the document can be accurately detected based on the both edges. The document size detecting device according to claim 1, wherein the image pickup device is a charge-coupled device (CCD) image sensor.

With this configuration, the edge of the document can be easily and accurately determined and detected.・ Detects the size of a document using a document reading device equipped with a light source that irradiates the document placed on the document table with light and an image sensor that reads an image on the document based on the reflected light from the document In the original size detection method, after the original mat opening / closing switch is turned on and before the original mat is completely closed, the original is read by the image sensor with the light source turned off and the light source turned on. And
By taking the difference between the read image data by the control means,
A document size detection method that determines the edge of a document.

With such a configuration, even in an environment affected by disturbance light such as a lighting fixture, the edge of the document can be accurately determined and easily detected.

[0031]

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, the control means for determining the edge of the document by determining the difference between the read image data in the light-off state and the read image data in the light-on state is provided. Even in an environment affected by disturbance light, such as a lighting fixture, the edge of the document can be accurately determined and detected.

According to the document size detecting apparatus of the second aspect, in addition to the effects of the first aspect, the difference between the read-out image data in the light-off state and the read-out image data in the light-on state can be easily determined. As a result, the influence of disturbance light can be reliably removed.

[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 a diagram showing various image data in a detection operation.

[Explanation of symbols]

11: Document mounting table, 12: Document, 12a: Edge, 13 ...
Document mat, 14: Document mat open / close switch, 15: Lamp unit as light source, 16: C as image sensor
CD image sensor, 21 ... CP constituting control means
U, 22: ROM constituting control means, 23: RAM constituting control means, 23a: first data storage section, 23b
... Second data storage unit.

Continuation of the front page (72) Inventor Osunori Okubo 1-2-28 Tamazo, Chuo-ku, Osaka City, Osaka Prefecture F-term (reference) 2H012 CA07 5C072 AA01 BA04 BA10 CA02 CA12 EA05 FB13 LA02 LA08 MB06 RA01 UA11 UA13 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 the document size detection device for detecting the size of the document, after the document mat opening / closing switch is turned on and before the document mat is completely closed, the light source is turned off and the light source is turned on by the image sensor. An original size detecting device provided with control means for reading an original and determining a difference between the read image data and an edge of the original. 2. The image processing apparatus according to claim 1, wherein the control unit performs black-and-white reversal processing on one of the read image data in the light-off state and the light-on state, and combines the inverted image data with the other read image data. 2. The document size detecting device according to claim 1, wherein a difference between the document sizes is obtained.