JP2003348301A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reading apparatus in which it is accurately detected that a head and a terminal of an original reach a reading position. <P>SOLUTION: A roller 19 for background switching having a white reference face 19a and a black face 19b is positioned while facing contact glass 24, such a confronted part is defined as the reading position and when the original is fed through a pickup roller 20, retard rollers 21a and 21b and feed rollers 22 and 23, and the head of the original is detected by a document sensor (DS2) 18, the roller 19 for background switching is rotated by half to switch the background at the reading position from the white reference face 19a to the black face 19b. When a white pixel is detected in an image read by a scanner 11 within prescribed time (steps N1), the detection of the white pixel becomes the detection of the head of the original reaching the reading position. <P>COPYRIGHT: (C)2004,JPO

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 having a function of reading a document image, such as a copying machine, a facsimile machine, and a multifunction machine having multiple functions such as a multifunction / fax function.

[0002]

2. Description of the Related Art Generally, when a document is read by an automatic document reading mechanism such as a facsimile machine, it is necessary to grasp the start and end of the document. Conventionally, a document sensor (DS2) is provided in front of a reading unit, and when the stepping motor rotates a predetermined number of steps N after the start of the document is detected by the document sensor (DS2), the start of the document is started. Is considered to have reached the reading position. Similarly, after the end of the document is detected by the document sensor (DS2), a predetermined number of steps N,
When the stepping motor rotates, it is assumed that the end of the document has reached the reading position, and the document is processed as a one-page document.

[0003]

In the above-described conventional image reading apparatus, a predetermined number of steps N occurs due to backlash of the rotating mechanism, slippage between the rollers and the document, and expansion and contraction of the document itself. When the stepping motor rotates, the start or end of the document does not always reach the reading position. That is, a slight advance and a delay may occur. Further, there is a problem that even if skew occurs in the document, it cannot be detected.

The present invention has been made in view of the above problems, and has as its object to provide an image reading apparatus capable of accurately detecting that the start and end of a document have reached a reading position. A second object of the present invention is to provide an image reading apparatus capable of detecting skew of a document.

[0005]

An image reading apparatus according to the present invention comprises: a document conveying means for conveying a document; and a document reading means for reading a document conveyed by the document conveying means one line at a time in the main scanning direction. A document which determines the start and / or end of the document based on whether the background color of the document reading position in the document conveying means is black and whether or not an image signal from the document reading means includes a white pixel; An edge determination unit is provided.

In the image reading apparatus of the present invention, the background color at the document reading position can be switched between a white reference color and black, and before the document is read, the background color is switched to the white reference color.
It may be read by the document reading means and used as reference data for correcting image data.

In the image reading apparatus of the present invention,
The document edge determination means calculates a skew amount of the document based on how a white pixel is detected in one line of image data and how it changes as the document is conveyed. An amount calculating means may be provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a block diagram showing a configuration of a multifunction peripheral as an embodiment of the image reading apparatus of the present invention. The MFP according to the present embodiment has multiple functions such as a copy function, a fax function, and a print function, as is generally well known.

This multifunction device includes an MPU1, an NCU2,
MODEM 3, ROM 4, RAM 5, image memory 6, CODEC 7, printer 8, display unit 9, keypad 10, scanner 11, image processing circuit 12,
, Shading RAM 13 and reading mechanism control circuit 1
4, a motor (M1) 15, a motor (M2) 16, a document sensor (DS1) 17, a document sensor (DS2) 18, and a background switching roller 19.

The MPU 1 has a function of controlling the entire multifunction peripheral of this embodiment. This MPU 1 includes an NCU (Ne
2 and a MODEM 3 are connected. The NCU 2 is controlled by the MPU 1 to control the connection between the line L and the multifunction peripheral, and has a function of transmitting a dial pulse according to the telephone number of the communication partner and a function of detecting an incoming call. The line L is connected to a general public telephone network (PSTN).

The MODEM 3 modulates and demodulates transmitted and received data,
Specifically, the transmission data, which is a digital signal, is modulated into an analog audio signal and transmitted to the line L via the NCU 2, and conversely, the analog audio signal received from the line L via the NCU 2 is converted into a digital signal. Demodulate into a signal.

The ROM 4 stores in advance programs and the like for controlling the operation of the multifunction peripheral as a whole. RAM5
Stores data necessary for control by the MPU 1 and data that need to be temporarily stored during the control operation. Image memory 6
Stores image data read by the scanner 11 and image data received from the outside via the line L and the MODEM 3. The CODEC 7 encodes the image data to be transmitted stored in the image memory 6, decodes the received image data, and stores the decoded image data in the image memory 6.

The printer 8 prints the received image data, the image data read by the scanner 11 or the image data stored in the image memory 10 on a sheet of paper, and stores and outputs a hard copy. The display unit 9 displays various information such as a telephone number, a FAX number, and a remaining amount of toner of the printer 8 which are input by operating the keypad 10. The keypad 10 includes a start key 10a, a mode switching key for setting various modes, a telephone number, a fax number, and the like.
It has numeric keys for inputting numbers, operation keys for instructing various operations, and the like.

The scanner 11 reads a document image using, for example, a CCD image sensor or the like. The image processing circuit 12 processes the original image read by the scanner 11
Image processing such as shading correction and binarization processing is performed. The shading RAM 13 stores shading correction data. The reading mechanism control circuit 14 includes a motor (M1) 15, a motor (M2) 16, a document sensor (DS1) 17, and a document sensor (DS2) 1.
8 is controlled. As the motor (M1) 15, for example, a stepping motor is used, and drives a roller for conveying a document. As the motor (M2) 16, for example, a stepping motor is used and drives switching of the roller 19 for background switching.

FIG. 2 schematically shows a reading mechanism of the multifunction peripheral according to the embodiment. The manuscript introduced from the manuscript setting unit 31
Detected by the document sensor (DS1) 17,
The retard rollers 21a, 21
b, and the transport rollers 22, 23 and the document sensor (DS2) from the retard rollers 21a, 21b.
After passing through the position 18, the document reaches the facing portion of the contact glass 24 and the background switching roller 19, which is the reading position of the document, and after reading, the document is discharged through the discharge rollers 29 and 30.

A document sensor (DS1) 17 is provided in front of the pick-up roller 20 on the conveyance path.
Document sensors (DS2) 18 are disposed behind the document sensors 2 and 23, respectively. The background switching roller 19 has a white reference surface 19a formed on one half, and a black surface 19b formed on the other half.
Are formed. The pickup roller 20, the retard rollers 21a and 21b, and the transport rollers 22 and 23 are driven by a stepping motor (M1) 15, and the half rotation of the white reference surface 19a and the black surface 19b of the background switching roller 19 is switched by a stepping motor (M2). 16.

The light from the light source 25 is applied to the background switching roller 19.
And the opposite surface of the contact glass 24 is irradiated. The light passing through the document hits the document, and the document image is
Scanner (CCD) 11 through 6, 27 and lens 28
And is read.

Next, an original image reading process in the MFP according to the embodiment will be described with reference to flowcharts shown in FIGS. When the process starts, in step ST1, it is determined whether the document sensor (DS1) 17 is on. When a document is set on the document setting section 31, the document sensor (DS1) 17 is turned on, and the process proceeds to step ST2. On the other hand, if the document sensor (DS1) 17 is not turned on, the process stands by at this step ST1 until a document is set.

In step ST2, driving of the stepping motor (M1) 15 is started. As a result, the pickup roller 20, the retard rollers 21a, 21
b, the conveying rollers 22 and 23 start rotating. Next, the process proceeds to step ST3. In step ST3,
The light source 25 is turned on. Subsequently, the process proceeds to step ST4. At this point, the background switching roller 19 is
9a faces the contact glass 24. In Step ST4, the white reference surface 19a of the roller 19 is read by the scanner 11, and the roller white reference surface read data is stored in the shading RAM 13. Next, step ST
Go to 5.

In step ST5, it is determined whether or not the document sensor (DS2) 18 is on. When the starting end of the document reaches the position of the document sensor (DS2) 18, the document sensor (DS2) 18 is turned on, so that the process proceeds to step ST7. On the other hand, if the document sensor (DS2) 18 is not turned on, step S
Move to T6. In step ST6, it is determined whether or not the stepping motor (M1) 15 has driven a predetermined number of steps N1. If the number of steps has not reached the predetermined number, the process returns to step ST5, where the document sensor (DS2) 18 is turned on or the number of steps is equal to the predetermined number N1.
Until the process reaches steps ST5 and ST6.

In step ST6, when the stepping motor (M1) 15 is driven by a predetermined number of steps N1,
Move to step ST30. In step ST30, the stepping motor (M1) 15 is driven by a predetermined number of steps N1, and originally the document sensor (DS)
2) This is a situation where 18 is supposed to be turned on but is not turned on. Here, the stepping motor (M1) 15 is turned off, and the process proceeds to step ST31. Step ST3
In 1, the display unit 9 displays "document jam".

In step ST7, the stepping motor (M1) 15 is stopped. With this, at the position where the starting end of the document reaches the document sensor (DS2) 18,
Stop the manuscript. Next, the process proceeds to step ST8. In step ST8, the stepping motor (M2) 1
6 is rotated, and the background switching roller 19 is rotated half a rotation (180
°) so that the black surface 19 b faces the contact glass 24. Next, the process proceeds to step ST9. Step ST
In step 9, it is determined whether the start key 10a has been turned on. When the user presses the start key 10a, the process proceeds to step ST10.

In step ST10, the rotation of the stepping motor (M1) 15 is started again. When the rotation of the stepping motor (M1) 15 starts, the document is again conveyed. Next, the process proceeds to step ST11.
In step ST11, a stepping motor (M
1) It is determined whether or not 15 has rotated a predetermined number of steps N2. After a predetermined number of steps of N2 rotations, it is determined that the starting end of the document has reached the reading position of the contact glass 24, and the process proceeds to step ST12. Step ST1
In 2, the variable L indicating the number of lines and the variable N indicating the number of steps are set to 0. Subsequently, the process proceeds to step ST13.

In step ST13, the scanner 1
In step 1, an original image is read, and the image data is captured.
Next, the process proceeds to step ST14. Step ST14
In, it is determined whether or not there is a white pixel in the captured image data. If there is no white pixel, step ST15
Move to. On the other hand, if there is a white pixel, step ST18
Move to. In step ST15, the stepping motor (M1) 15 is driven by one line. As a result, the original is sent by one line, and the process proceeds to step ST16. In step ST16, the variable N is incremented by one. Then, the process proceeds to step ST17.

In step ST17, it is determined whether or not the variable N has reached a predetermined number N3. Variable N is a predetermined number N
If the number has not reached 3, the process returns to step ST13.
Import line image data. Steps ST13 to ST1 are performed until either the white pixel exists in the image data to be captured or the variable N reaches a predetermined number N3.
Step 7 is repeated. When the variable N reaches the predetermined number N3 in step ST17, the process proceeds to step ST30. In step ST30, the stepping motor (M1) 15 is rotated by a predetermined number of lines N3,
Originally reading of the original should start,
Since there are no white pixels in the read image and the original has not yet arrived, the stepping motor (M1)
Stop No. 15. Then, the process proceeds to step ST31,
"Document jam" is displayed on the display unit 9, and the process is terminated.

In step ST18, the number of white pixels is 9
It is determined whether it is 0% or more. If the white pixels have not reached 90%, the process proceeds to step ST19. On the other hand, when the white pixels are 90% or more, the process proceeds to step ST20. In step ST19, the variable L is incremented by one. Then, the process returns to step ST13. In step ST13, image data of the next line is captured by the scanner 11, and it is determined whether or not there is a white pixel. Then, while incrementing the variable L by 1 until the white pixels become 90% or more, the process proceeds to step ST1.
3. The processing of ST14, ST18, ST19 is repeated.
If the document has skew, the number of white pixels in the first read data is small, and the steeper the skew, the smaller the number of white pixels thereafter, and the larger the count value of the variable L.

In step ST20, the variable L is stored in the RAM 5 as the skew correction amount. Next, step S
Move to T21. In step ST21, the stepping motor (M2) 15 is rotated, the background switching roller 19 is rotated by half (180 °), and the white reference surface 19a is made to face the surface of the document. Next, the process proceeds to step ST22. In step ST22, the stepping motor (M1) 15 is driven for one line. As a result, the original is fed by one line. Next, the process proceeds to step ST23. In step ST23, 1
Read the image data for the line. And step S
The process moves to T24. In step ST24, it is determined whether or not the document sensor (DS2) 18 has been turned off. If not turned off, the process returns to step ST22,
Continue reading the original. On the other hand, if the document sensor (DS2) 18 is turned off, the process proceeds to step ST25. Turning off the document sensor (DS2) 18 means that the end of the document has passed that position.

In step ST25, the stepping motor (M1) 15 is driven by one line. As a result, the original is fed by one line. Then, step ST
Move to 26. In step ST26, one line of image data is read by the scanner 11 and the image processing circuit 12. Next, the process proceeds to step ST27. In step ST27, it is determined whether or not there are no white pixels in the read image. If there are no more white pixels, the process proceeds to step ST29. on the other hand,
If there are no more white pixels, it is determined that reading of the document has been completed, and the process proceeds to step ST28. Step S
At T28, the stepping motor (M1) 15 is driven to discharge the original from the discharge rollers 29 and 30. This completes the reading process.

In step ST29, it is determined whether the stepping motor (M1) 15 has been driven a predetermined number of steps N3. If the predetermined number of steps N3 has not been driven, the process returns to step ST25, and the process returns to step ST25 until there is no white pixel or the number of drives of the stepping motor (M1) 15 reaches the predetermined number of steps N3. The processing of ST26, ST27, and ST29 is repeated, and reading of the document is continued. Step ST2
In 9, when the driving of the stepping motor (M1) reaches the predetermined number of steps N3, the process proceeds to step ST30. In step ST30, the stepping motor (M1) 15 is stopped, and
In step 1, "document jam" is displayed on the display unit 9.

In the above embodiment, a CCD is shown as an example of the scanner, but the contact type image sensor (C
IS) may be used as the document reading means. Further, the switching of the background color of the document reading apparatus is performed in a roller shape which is rotated by a stepping motor (M2) 16 different from the stepping motor (M1) 15 for document feeding, but is not limited to this. For example, a plate in which a white reference color and a black color are separately applied may be slid.

[0031]

According to the first aspect of the present invention, the background color of the document reading position is set to black, and whether or not a white pixel is included in the image signal from the document reading means is determined. Since the document end determining means for determining the start and / or end of the document is provided, the start or end of the document can be determined from the image signal and can be accurately determined.

According to the second aspect of the present invention, the background color is switched between the white reference color and black, so that data for peak correction and shading correction can be obtained before reading the original. Can be.

Further, according to the third aspect of the present invention, when a white pixel is detected in one line of image data, how the white pixel changes as the document is conveyed is determined. Is provided, the start or end of the document can be accurately determined, and the skew of the document can also be detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a multifunction peripheral according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a reading mechanism of an image reading unit of the multifunction peripheral according to the embodiment.

FIG. 3 is a flowchart illustrating a document reading process of the multifunction peripheral of the embodiment.

FIG. 4 is a flowchart illustrating a document reading process of the MFP according to the embodiment, together with FIG. 3;

FIG. 5 is a flowchart illustrating a document reading process of the MFP according to the embodiment, in conjunction with FIGS. 3 and 4;

[Explanation of symbols]

1 MPU 2 NCU 3 MODEM 4 ROM 5 RAM 6. Image memory 7 CODEC 8 Printer 9 Display 10 keypads 11 Scanner 12 Image processing circuit 13 Shading RAM 14 Reading mechanism control circuit 15 Stepping motor (M1) 16 Stepping motor (M2) 17 Document Sensor (DS1) 18 Document Sensor (DS2) 19 Background switching roller 19a White reference plane 19b black face 20 Pickup roller 21a, 21b retard roller 22, 23 transport roller 24 contact glass 25 light source 31 Original setting section

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/00 108 H04N 1/04 103E 1/19 1/12 Z F term (Reference) 2H108 AA05 FA01 FA21 FA29 FA31 5B047 AA01 BA01 BB02 BC05 BC09 BC11 BC14 BC18 CA09 CB09 CB22 DA04 DC01 DC06 DC09 5C062 AA02 AA05 AB02 AB17 AB32 AB33 AB41 AB42 AC02 AC11 AC65 5C072 AA01 BA04 CA02 DA02 DA04 EA05 NA01 RA03 RA04 RA01 X02

Claims (3)

[Claims] 1. An image reading apparatus comprising: a document conveying means for conveying a document; and a document reading means for reading a document conveyed by the document conveying means line by line in a main scanning direction. Set the background color of the scanning position to black,
An image reading apparatus, comprising: a document end determining unit that determines a start and / or end of a document based on whether a white pixel is included in an image signal from the document reading unit. 2. The background color at the document reading position is switchable between a white reference color and black. Before reading a document, the background color is switched to a white reference color, which is read by a document reading means. 2. The image reading apparatus according to claim 1, wherein the image reading apparatus is used as reference data for correction. 3. The document edge judging means determines the amount of skew of a document when a white pixel is detected in one line of image data and how it changes as the document is conveyed. The image reading apparatus according to claim 1, further comprising a skew amount calculating unit configured to calculate the skew amount.