JP2003110805A - Original image reading method for image reading optical system unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading method capable of detecting the stain of a contact glass to prevent the stain from reflecting on an image. SOLUTION: An image reading optical system unit reads an original image by receiving the light reflected from the original on a contact glass where the original passes. A reference reflection sheet 50 is provided across the entire original-reading position of an original-transportation guide member 47 positioned on the contact glass. The reflected light from the reference reflection sheet is received in advance through a clean contact glass surface, so that the reference reflection sheet information is acquired as a reference data. Before reading the original image, the reflected light from the reference reflection sheet is received to acquire the information for the contact glass surface at a position for reading the original, which is compared with the reference data. Thus, the stain on the contact glass surface is detected, and the original is automatically fed to read the original image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document image reading method using an image reading optical system unit used in an image forming apparatus having an automatic document feeding device.

[0002]

2. Description of the Related Art In an image forming apparatus using electrophotography, the surface of a photosensitive drum is uniformly charged, and the charged surface of the photosensitive drum is irradiated with light (image exposure) based on certain image information. To form an electrostatic latent image (charge image),
The electrostatic latent image is developed using a developer containing toner charged to a predetermined polarity, the obtained toner image is transferred to the surface of a transfer sheet such as paper or OHP film, and the transferred toner image is heated by a heat roller ( An image is formed by heat fixing with a fixing roller). In such an image forming process, the above image information is obtained by an image reading optical system unit called an ISU (image scanner unit), and an electrostatic latent image is formed by irradiating the charged surface of the photosensitive drum with light. That is, the writing of image information is L
It is performed by a writing unit called SU.

Such an image reading optical system unit (ISU) has a contact glass (original plate) on its upper surface.
Is provided with a light source such as a halogen lamp, a reflection mirror, an optical lens and a CCD element under the light source. The light source irradiates the original on the contact glass with light, and the reflected light from the original is reflected by the reflection mirror or CC through optical lens
By receiving light with the D element, predetermined image information (original information) is read. That is, the image information read here is output, laser light irradiation is performed by the LSU according to the output value (CCD output value), and an electrostatic latent image is formed on the surface of the photoconductor drum. Is executed.

[0004]

By the way, in many image forming apparatuses such as copying machines currently on the market, an automatic document feeder is provided on a document cover attached to the upper surface of the apparatus, and many of them are provided. When images are formed on a single document, the document is automatically fed continuously to allow the document to pass through the contact glass, and the document image is read by the ISU described above when the document is passed. ing. However, when a large number of originals are automatically fed and an image is read in this way, if dust or the like adheres to the contact glass and becomes dirty, all the images obtained from the large number of originals will be dusted. Has the inconvenience of being reflected.

Therefore, it is an object of the present invention to provide an image reading method capable of detecting dirt even if dirt or the like is attached to the contact glass.

[0006]

According to the present invention, at least a light source is arranged on the lower surface of a contact glass through which an automatically fed document passes, and the reflected light of the document on the contact glass from the light source is received by a CCD element. In the image reading optical system unit for reading the original image, the guide member for conveying the original document located on the contact glass is provided with a reference reflection sheet over the entire original reading position. By receiving the reflected light from the reference reflection sheet via the CCD element, the reference reflection sheet information is acquired as reference data, and the reference reflection sheet is read prior to the reading of the automatically fed document image. The reflected light from the CC
Information on the contact glass surface at the document reading position is obtained by receiving light by the D element, and by comparing this with the reference data, dirt on the contact glass surface is detected, and then the document is automatically fed. A document image reading method is provided which is characterized in that the document image is read.

That is, according to the present invention, the reference reflection sheet is provided on the document conveyance guide arranged at the document reading position, and the reflected light is received by the CCD element, and the contact glass surface is obtained according to the information obtained. It is possible to detect dirt caused by the attachment of dust or the like. Therefore, when dirt due to adhesion of dust or the like on the contact glass surface is detected, the information is displayed on, for example, the monitor section (operation panel section) of the image forming apparatus, so that a general user can copy many originals. Before automatic feeding,
The contact glass surface can be cleaned, which effectively avoids the inconvenience that dirt such as dust is reflected on the images obtained from many originals. Further, when dirt due to adhesion of dust or the like is slight, for example, based on the stain information, the image information of the read document is corrected by image processing to reflect the dust or the like in the formed image. Can be effectively avoided.

In the present invention, the reference reflection sheet is
Any material having a certain reflectance can be used without particular limitation, but it is generally preferable to use a white sheet having a high reflectance.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to specific examples shown in the accompanying drawings. FIG. 1 is a diagram for explaining an image forming process of an image forming apparatus including an ISU for carrying out the original image reading method of the present invention.
FIG. 4 is a diagram showing a schematic structure of an ISU together with a document cover, FIG. 3 is an enlarged side view of an essential part showing a mounting position of a reference reflection sheet used in the present invention, and FIG.
FIG. 4 is a bottom view of the reference reflection sheet attachment position shown in FIG. 3.

Referring to FIG. 1, in an image forming apparatus having an image reading optical system unit (ISU), a photosensitive drum 1 is rotatably mounted, and the photosensitive drum 1 is rotated around the photosensitive drum 1. A main charging device 2, a developing device 3, a transfer and paper separating device 4 and a cleaning device 5 are provided along the direction. Further, although not shown, a static eliminator is provided between the transfer / paper separation device 4 and the cleaning device 5 or between the cleaning device 5 and the main charging device 2. That is, by the main charging device 2, the photosensitive drum 1
Is uniformly charged to a predetermined polarity and then an electrostatic image is formed by light irradiation based on predetermined image information.
The electrostatic latent image formed on the surface of the photoconductor is developed by the developing device 3, whereby a toner image corresponding to image information is formed. This toner image is transferred onto a transfer sheet (not shown) such as paper that has been conveyed between the photoconductor drum and the transfer / paper separation device 4, and the transfer sheet on which the transfer toner image is formed is Then, the toner image is supplied to a fixing device (not shown), and the toner image is fixed on the transfer sheet by heat, pressure, or the like. The transfer sheet on which the toner image is fixed in this manner is discharged to the outside of the apparatus. On the other hand, after the toner image is transferred, the cleaning device 5 cleans the residual toner on the surface of the photosensitive drum 1,
Further, the charge is removed, thereby completing one cycle of image formation.

In the above-mentioned image forming apparatus, the image information for forming the electrostatic latent image is read by the ISU 20 and the LSU (writing optical system unit) 1 is read based on this image information.
2, the surface of the photosensitive drum 1 is irradiated with light.
The LSU 12 includes a laser light source such as a laser diode, a polygon mirror, and the like, and irradiates the surface of the photosensitive drum 1 with laser light based on the above image information.

Optical system unit 2 for reading image information
0, or ISU, has the structure shown in FIG. Referring to FIG. 2 showing a schematic structure of this ISU 20, contact glasses 22a and 22b are provided on the upper surface of this unit 20.
Is attached. The contact glass 22a is for reading an image of a document conveyed by an automatic document supply mechanism described below,
As is clear from FIG. 2, the width is small. On the other hand, the contact glass 22b has a large area, and the image information of the original placed on the contact glass 22b is read.

On the other hand, on the bottom wall 25 of the ISU 20, there are provided a light source 30, a reflection mirror 32, an optical lens 34, and a CCD unit 4 having a CCD element 36.
0 is provided. In the ISU 20, the light source 30 and the like is held so as to be scannable by wire driving or the like, and the original on the contact glass 22a or 22b is irradiated with light from the light source 30, and the reflected light of the original is reflected by the reflection mirror 32 and the optical lens. CCD element 36 through 34
The CCD device 36 is arranged so as to receive light at
The image information is read with. That is, the read image information is output from the CCD element 36 to the LSU 12, and image exposure based on the image information is performed.

On the other hand, a document cover 40 is provided on the upper surface of the ISU 20 so as to be openable and closable. The document cover 40 is provided with an automatic document feeding mechanism, a document placing plate 41 is provided on the upper portion, and a document receiving portion 42 is provided on the lower side of the document placing plate 41. That is, the document 43 placed on the document plate 41 is driven by a predetermined feeding roller.
In FIG. 3, the sheet is conveyed along a path indicated by L and is discharged onto the document receiving section 42 via the sheet discharging roller. The document transport path L
As can be understood from the above, a document conveying guide 47 is provided on this path, and the conveyed document 43 is guided by the guide 47 and the narrow contact glass 22a described above.
And (the image reading area). That is, the manuscript 43
However, when passing through this image reading area, the light source 30 is positioned below the contact glass 22a, and the original 43 passing through this area is irradiated with light from the light source 30, and the reflected light is reflected as described above. As described above, the CCD element 36 receives light. When the automatic document supply mechanism is not used, the document 43 is placed on the large area contact glass 22b, and the image is read with the document cover 40 closed. In this case, by scanning the light source 30, the image information (document reflected light) on the entire document 43 is received by the CCD element 36.

As described above, the image information read as described above is output by the CCD element 36, and image exposure is performed by the LSU 12 based on this output value to form, develop and transfer an electrostatic image. The above process is performed to form an image on the transfer sheet. In such an image forming process, many originals are automatically fed,
When the image of the original is read by the ISU 20, the image is exposed (the image is written) by the LSU 12 based on the read image information, and when the image is formed, especially the surface of the contact glass 22a must be kept clean. I won't. If dust or the like adheres to this surface and is dirty, dust or dirt is reflected on the obtained image for all of a large number of originals. (Place the original on the contact glass 22b, close the original cover,
In the case of forming an image for each sheet, the presence of dirt such as dust is known when one image is obtained, and the surface of the contact glass 22b may be cleaned. Contamination on the surface of the contact glass 22b does not pose a problem as much as when an image is formed. )

In the present invention, a reference reflection sheet is provided on the lower surface of the document conveying guide 47 in order to detect the stain on the surface of the contact glass 22a as described above. That is, in FIGS. 3 and 4 showing the mounting position of the reference reflection sheet, along the document reading position X, on the lower surface of the document conveying guide 47 arranged on the document conveying path L described above,
For example, a reference reflection sheet 50 made of a white sheet is provided. A contact glass 22a having a small width is arranged below the reference reflection sheet 50, and the contact glass 22 having a large area is adjacent to the contact glass 22a.
A document size indicating plate 52 provided at the peripheral portion of b is located. As can be seen particularly from FIG. 4, the reference reflection sheet 50 is provided on the lower surface of the document conveyance guide 47.
The maximum width of the original extends from inside the reading area Z to outside the reading area Y, and all the originals pass between the reference reflection sheet 50 and the upper surface of the contact glass 22a.

According to the present invention, the original image is read by using the reference reflection sheet 50 arranged at the above-mentioned position. First, the ISU 20 is operated in advance, and the reflected light from the reference reflection sheet 50 through the clean contact glass surface 22a is received by the CCD element 36 to obtain the information of the reference reflection sheet 50 as reference data. Keep in memory.

Next, prior to reading the automatically fed document image, the ISU 20 is operated, the reflected light from the reference reflection sheet 50 is again received by the CCD element 36, and the surface of the contact glass 22a at the document reading position X is detected. Acquire information (glass surface information). By comparing this glass surface information with the previously stored reference data, it is possible to detect the stain on the contact glass surface 22a due to the adhesion of dust or the like.

Therefore, when the dirt is detected, the information (dust existence information) is displayed on the monitor unit (operation panel) of the ISU 20 or the image forming apparatus. This allows
A general user can remove dust and the like by wiping the surface of the contact glass 22a prior to reading an image by automatically feeding the original.

After the cleaning is completed, the image is read by the automatic feeding of the document by the operation of the ISU 20 according to a conventional method, for example, by a switch or the like provided on the operation panel. If no dirt is detected on the contact glass surface 22a, the cleaning is not performed and the ISU is continued in accordance with the usual method.
The document image is read by operation 20.

After the original image is read, the CCD output (read image) based on the read information is LSU.
12 and the predetermined image forming cycle is executed,
A copy image corresponding to the original image is obtained.

According to the present invention, when dirt on the contact glass surface 22a is detected in accordance with the above-described operation, if the dirt is relatively slight, the cleaning is not performed and the original image is continuously printed. After the reading, it is preferable to correct the read image by image processing. The correction by this image processing is carried out by transmitting the output of the CCD element 36 to an appropriate control device or the like and by the same principle as the data compression in the computer, and the image information corrected in this way is LSU.
By transmitting to 12 and forming an image, it is possible to effectively avoid the inconvenience that the dirt on the surface of the contact glass 22a is reflected in the obtained image.

[0023]

As described above, according to the present invention, the reference reflection sheet is provided at the document reading position, and the data of the reflected light from this sheet is used to detect the stain on the contact glass surface, By the cleaning and the image correction based on the detection information, it is possible to effectively prevent the inconvenience that the dirt on the contact glass surface is reflected on the image obtained by automatically feeding a large number of originals.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an image forming process of an image forming apparatus having an ISU for carrying out a document image reading method of the present invention.

FIG. 2 is a diagram showing a schematic structure of an ISU together with a document cover.

FIG. 3 is an enlarged side view of essential parts showing a mounting position of a reference reflection sheet used in the present invention.

FIG. 4 is a bottom view of the reference reflection sheet attachment position shown in FIG.

[Explanation of symbols]

1: photoconductor drum 12: LSU 20: ISU 22a, 22b: Contact glass 36: CCD element 40: Original cover 47: Document transport guide 50: Reference reflection sheet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Ishizaki             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. (72) Inventor Kei Ouchi             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. F term (reference) 2H076 AA04 AA07 AA54 AA58 BB06                       BB10 DA05 DA08 DA31                 5B047 AA01 BA01 BB02 DC06                 5C051 AA01 BA03 DA03 DB01 DB07                       DB28 DC03 DC07 EA08 FA01                 5C072 AA01 BA17 DA21 EA05 FB25                       NA01 RA10 RA16 UA01 XA01                 5C077 LL02 LL11 MM03 NP01 PP05                       PP43 PQ20 SS01 TT06

Claims (3)

[Claims] 1. An image reading optical system in which at least a light source is arranged on a lower surface of a contact glass through which a document to be automatically fed passes, and a reflected light of the document on the contact glass from the light source is received by a CCD element to read a document image. In the unit, the document conveying guide member located on the contact glass is provided with a reference reflection sheet over the entire document reading position, and the reference reflection sheet from the reference reflection sheet is previously passed through a clean contact glass surface. By receiving the reflected light by the CCD element, the reference reflective sheet information is acquired as the reference data, and the reflected light from the reference reflective sheet is received by the CCD element before reading the automatically fed document image. Information on the contact glass surface at the document reading position is acquired by using A method for reading an original image, characterized by detecting dirt on the contact glass surface by comparing with the quasi data, and then automatically feeding the original to read the original image. 2. The document image reading method according to claim 1, wherein the detection information of the dirt on the contact glass surface is displayed on the monitor unit prior to automatic document feeding. 3. The document image reading method according to claim 1, wherein the read document image is corrected based on the detection information of the stain on the contact glass surface.