JP2004029119A - Original reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original reader which suppresses and prevents unwanted image information from being read out due to stains stuck to a platen glass and hardly causes an out of focus in the read image. <P>SOLUTION: This original reader is provided with the platen glass 40 in contact with a conveyed original MP and an optical unit which reads image information from the original MP on the platen glass 40. The platten glass 40 is held in holding frames 41, 41A, and one or more coil springs 42 are interposed between the platen glass 40 and the holding frame 41. Then the platen glass 40 is slid in the direction parallel to the conveying direction of the original MP in accordance with the contact or non-contact of the platen glass with the original MP based on the spring-energizing force of the coil spring 42. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a document moving type document reading apparatus used as a copier, a scanner, or the like.
[0002]
[Prior art]
As a document reading method in a copying machine, a scanner or the like, there are a document fixing method and a document moving method. The former document fixing method is a method of reading image information of a document on the platen glass by scanning the length of the document with an optical unit for reading the document installed below the platen glass (document mounting table). Say.
On the other hand, in the latter document moving method, the position of the optical unit is fixed, a platen glass is set above the optical unit, and the document MP moves on the platen glass, so that the optical unit transfers the image information of the document. Refers to the reading method. Although this original movement method has an excellent advantage, when the original comes into contact with the platen glass, dirt such as dust of the original is transferred to the platen glass, and this dirt is used as unnecessary image information at the next reading of the original. There is a problem of being read.
[0003]
As means for solving such a problem, there is disclosed a technique of reading a document in a state where the document is floated from a platen glass in a document reading section (for example, see Japanese Patent No. 3134773). In this technique, for example, as shown in FIG. 10, a plurality of projection members are installed on a platen glass 40, the original MP is separated from the platen glass 40 by the plurality of projection members, and the stain of the original MP is applied to the platen glass 40. This is to prevent the image from being suppressed.
[0004]
[Problems to be solved by the invention]
However, in the above technique, as shown in FIG. 11, when the original MP is carried into the original reading section, the original MP is kept on the platen glass 40 until the leading end of the original MP is caught by the transport roller 26A which is a roller in the next process. Contact. When the original MP is discharged from the original reading unit, the distal end of the original MP discharged from the transport roller 26 </ b> B contacts the platen glass 40.
As described above, since the original MP and the platen glass 40 come into contact with each other when the original MP is loaded and discharged, dirt on the original MP is transferred to the platen glass 40 after all. Therefore, the problem that unnecessary image information is read in the document reading unit due to the dirt attached to the platen glass 40 cannot be solved.
[0005]
Further, in the technique described in the above-mentioned publication, the reading position of the document MP differs between the case where the document MP is bitten by both of the transport rollers 26A and 26B and the case where it is not. That is, when the original MP is transported, the original reading height of the optical system changes, so that the read image may be out of focus.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses reading of unnecessary image information due to dirt attached to a platen glass, thereby reducing the possibility of defocusing of a read image. It is intended to provide a device.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a platen glass that comes in contact with the conveyed document, and an optical unit that reads image information from the document on the platen glass. ,
The platen glass is held in the holding member, and an elastic member is interposed between the platen glass and the holding member. Based on a pressing force of the elastic member, the platen glass is brought into contact with the document according to the presence or absence of contact with the document. It is characterized by being slidable in a direction substantially parallel to.
[0008]
Here, the elastic member in the claims includes at least one or a plurality of various spring members, rubber, sponge, and more specifically, a coil spring or the like.
[0009]
According to the first aspect of the present invention, in the original moving system in which the original is transported so that the platen glass comes in contact with the original, dirt of the original may adhere to the platen glass at a contact portion between the platen glass and the original. It is known that the portion where the stain is generated is the leading end of the contact between the platen glass and the original, and when the area is the original reading area, a streak-like stain occurs in the read image.
[0010]
According to the first aspect of the present invention, when the leading edge of the document comes into contact with the platen glass, the platen glass is slid by the leading edge of the document and the conveying pressure of the document, and the stained portion generated on the platen glass is read. Since the image is moved outside, no noise is added to the read image, only necessary image information can be read, and improvement in print quality can be expected. In particular, when it is not possible to determine whether the transmitted data is only necessary image information as in the case of the FAX function, the effect of the present invention is further improved. Further, if the platen glass can be slid in the direction of transport of the original when the original is transported, the contact portion between the original and the platen glass can be separated from the reading position of the original when the original is transported.
[0011]
According to the second aspect of the present invention, if the urging force of the elastic member is used, the platen glass can be moved by contact between the original being transported and the platen glass. When the conveyance of the document is completed, the platen glass returns to the original position.
According to the third aspect of the present invention, since the movement width of the platen glass is larger than the area where the document and the platen glass are in contact with each other, the contact area can be completely separated from the reading position of the document.
Further, according to the present invention, it is possible to remove stains and the like adhered to the platen glass after the document is conveyed. For example, even if the frictional force of various originals against the platen glass changes, the life of normal image reading can be extended by cleaning the stain on the platen glass.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. In an image forming apparatus including a document reading apparatus according to the present embodiment, a document MP to be read is arranged as shown in FIGS. An original table 1 made of transparent glass or the like and a movable original reader 20 for moving an original MP when reading an original are provided.
[0013]
A scanner optical system 2 is provided below the document table 1 and the moving document reading device 20. The scanner optical system 2 includes a scanning unit 3, an imaging lens 4 located in an optical path, and a photoelectric conversion element (hereinafter, referred to as a CCD) 5, and has a function of reading a document image of the document table 1 or a moving document reading device 20. I do. The scanning unit 3 includes an exposure light source 6 for irradiating the original MP with light, and a reflected light from the original MP, for example, as shown by a dashed line in FIG. (Right) a plurality of reflecting mirrors 7, 8 and 9 for guiding to the CCD 5, which functions to expose the original MP and guide the reflected light from the original MP to the CCD 5 via the imaging lens 4. .
[0014]
The scanning unit 3 scans and exposes the document MP while moving at a constant speed from left to right along the document table 1 when reading in the document fixed method. The original MP is exposed after being stopped below the reading position of the apparatus 20. The components described above cooperate to constitute a scanner unit.
[0015]
The CCD 5 reads the original image data. The read image data is subjected to image processing by a control unit (not shown), and then sent to a laser scanning unit (hereinafter, referred to as LSU). Is irradiated onto the surface of the drum-shaped photoconductor 10 rotating in the direction of the arrow to form an electrostatic latent image on the photoconductor 10. A developing device 11 is provided around the photoreceptor 10 to develop an electrostatic latent image on the surface of the photoreceptor 10 exposed to the laser from the laser irradiation point toward the rotation direction of the photoreceptor 10 into a visible image with toner. A transfer charger 12 for transferring a toner image on the body 10 to a sheet, a main charger 13 for charging the photosensitive body 10 to a predetermined potential, and an LSU for irradiating a laser irradiation point of the photosensitive body 10 with a laser are provided. Such components cooperate to form an image forming unit.
[0016]
The image information of the original MP is transferred to the transfer paper TP, and the transfer paper TP is stored in the paper tray 14 and discharged next to the image forming unit, in other words, discharged above and below the scanner unit. You. A pickup roller 15 for feeding the transfer paper TP is pivotally supported at the leading end of the paper tray 14, and a paper input sensor switch for detecting the passage of the transfer paper TP toward the downstream direction, the paper input sensor switch The registration roller 16 for aligning the toner image on the photoreceptor 10 with the transfer paper TP based on the signal of the photoreceptor 10, the fixing roller 17 for fixing the toner image on the transfer paper TP by heat, and the transfer paper A paper discharge detection switch for detecting that the TP has passed, and a paper discharge roller 18 for discharging the transfer paper TP are provided.
[0017]
Next, the configuration of the moving document reading device 20 will be described with reference to FIG. 2. The moving document reading device 20 of the present embodiment is not of a fixed document type but of a document moving type. The moving document reading device 20 supplies and conveys the documents MP arranged on the document tray 21 to the main conveyance path one by one by the pickup roller 15 and the valley plate 23. The transported document MP is confirmed to be transported by the document input sensor 24, stops temporarily before the PS roller 25 for adjusting the position of the leading end and the image reading timing, and is re-transported by the PS roller 25. Then, the document passes through the document reading position (platen glass 40, document pressing plate 43) in a state where the timings are matched.
[0018]
When the original MP passes through the original reading position, the exposure light source 6 irradiates the original MP with light, and reflected light from the original MP is sent to the CCD 5 via the reflecting mirrors 7, 8, 9 and the imaging lens 4. . When the reflected light is sent to the CCD 5 in this way, the CCD 5 reads the reflected light as an electric signal (image data), and the image data is subjected to image processing by the control unit.
The read original MP passes through a reversible rotatable paper output roller 27 of a paper output unit via a transport roller 26, and the traveling direction of the original MP is determined by the position where the intermediate tray swing plate 28 is arranged, The document is conveyed to the intermediate tray 29 or the document discharge tray 30.
[0019]
Next, a document reading process of the moving document reading device 20 having such a configuration will be described. First, when the “single-sided reading process” is selected by the user, the position of the intermediate tray rocking plate 28 of the document discharge unit is changed to a position for supplying the document MP to the document discharge tray 30. Then, the original MP to be read is conveyed by the pickup roller 15, temporarily stopped before the PS roller 25, and is again conveyed by the PS roller 25 in synchronization with the reading timing of the original MP. The document MP thus re-conveyed is read at the document reading position, and the image data read from the document MP is transmitted from the CCD 5 to a control unit (not shown). The control unit performs image processing on the image data and drives the LSU of the image forming unit to irradiate the surface of the photoconductor 10 with a laser to form an electrostatic latent image based on the image data.
[0020]
While the image data is being processed, the read original MP is conveyed to a discharge roller 27 via a conveyance roller 26, and the rotation of the discharge roller 27 for discharging and the intermediate tray swing plate 28 The document is guided to the document discharge tray 30 to read a one-sided document.
The document reading apparatus can also read a double-sided document, but since it is not directly related to the features of the present invention, a description of a reading operation of a double-sided document is omitted.
[0021]
Next, a detailed configuration of the platen glass 40 and the document pressing plate 43 at the document reading position will be described with reference to FIG.
The platen glass 40 is a transparent glass plate for supporting the document MP being conveyed. The scanner optical system 2 functions to read image data from the original MP via the platen glass 40. The platen glass 40 is slidably fitted and supported in holding frames 41 and 41A having a substantially U-shaped cross section. A coil spring 42 is interposed between one end of the holding frame 41 and the holding frame 41.
[0022]
Based on the biasing force of the coil spring 42, the platen glass 40 slides in a direction parallel to the transport direction of the document MP depending on the presence or absence of contact with the document MP. The platen glass 40 slides by the frictional force with the document MP being conveyed, but the elastic force of the coil spring 42 is set to be smaller than the frictional force. The slide width of the platen glass 40 is set to be larger than the contact area between the document MP and the platen glass 40.
[0023]
The original pressing plate 43 has a function of pressing the original MP against the platen glass 40 by pressing the original MP being conveyed. That is, it is possible to prevent the transported original MP from having a gap with respect to the platen glass 40 or to prevent the reading distance from the scanner optical system 2 from being changed due to the difference in the thickness of the original MP. The original MP is arranged so as to keep a constant distance between the reading surface of the original MP and the scanner optical system 2, and is transported by the PS roller 25 and the transport roller 26.
[0024]
Next, the operation of the platen glass 40 when the document MP to be read passes through the document reading position will be described with reference to FIG.
First, as shown in FIG. 4, the original MP to be read is sent to the original reading position by the PS roller 25. In this manner, the original MP is sent to the original reading position, and when the leading end of the original MP contacts the platen glass 40 as shown in FIG. 5, the platen glass 40 is moved by the frictional force between the leading end of the original MP and the platen glass 40. When the platen glass 40 slides in a direction parallel to the direction in which the MP is transported and the coil spring 42 is compressed to the maximum, the platen glass 40 stops and the original MP is continuously transported (see FIG. 6).
[0025]
Next, when the end of the document MP passes the reading position, as shown in FIG. 7, the contact area between the document MP and the platen glass 40 gradually decreases, and the frictional force between the document MP and the platen glass 40 also decreases. As a result, the urging force acting on the coil spring 42 decreases. Due to this decrease in the urging force, the platen glass 40 slides in the direction opposite to the direction in which the document MP is conveyed. When the end of the document MP moves away from the platen glass 40, the urging force acting on the platen glass 40 becomes zero and the urging force acting on the coil spring 42 also becomes zero, as shown in FIG. The platen glass 40 returns to its original position and stops.
[0026]
Next, the reason why the platen glass 40 can be slid in a direction parallel to the transport direction of the document MP will be described with reference to FIG.
When the original MP is conveyed to the original reading position by the PS roller 25, the leading end of the original MP comes into contact with the point A on the platen glass 40. A frictional force is generated between the moving document MP and the platen glass 40, and this frictional force largely acts between points A and C on the platen glass 40.
[0027]
On the other hand, when the document MP comes into contact with the platen glass 40, dirt on the document MP adheres to the platen glass 40. Here, the amount of dirt moving from the document MP to the platen glass 40 is correlated with the frictional force acting on the contact point. Therefore, as shown in FIG. 9, the distribution of the amount of dirt on the platen glass 40 increases between the points A to C and is slightly lower on the downstream side than the point C where the frictional force is small. Therefore, when the platen glass 40 is fixed and the document MP is read with the points A to C set as the reading position of the document MP, the scanner optical system 2 reads out the image from the document MP and also removes stains on the platen glass 40. The problem of reading occurs.
[0028]
However, according to the present embodiment, the platen glass 40 slides in the conveying direction of the document MP due to the frictional force with the document MP, and therefore, the portions where the frictional force between the platen glass 40 and the document MP is large (points A to C). ) Can be removed from the reading position of the document MP, and a portion where the frictional force is small (downstream from the point C) can be shifted to the reading position of the document MP. Thus, the portion of the platen glass 40 with less dirt can be shifted to the reading position of the original MP, and the problem of reading dirt on the platen glass 40 simultaneously with reading the image can be solved.
[0029]
By providing cleaning members for removing stains on the platen glass 40 at both ends of the slide area of the platen glass 40, stains and the like adhering to the platen glass 40 after the original MP is transported can be easily removed. . Even if the frictional force of the various originals MP on the platen glass 40 changes, the life of normal image reading can be greatly extended by cleaning the stain on the platen glass 40.
[0030]
【The invention's effect】
As described above, according to the present invention, the platen glass is held in the holding member, an elastic member is interposed between the platen glass and the holding member, and the platen glass is moved based on the pressing force of the elastic member. It can be slid in a direction substantially parallel to the direction of document transport depending on the presence or absence of contact with the document, so that unnecessary image information due to dirt attached to the platen glass is suppressed or prevented from being read. This has the effect of reducing the possibility of occurrence of out-of-focus blur.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing an image forming apparatus in an embodiment of a document reading apparatus according to the present invention.
FIG. 2 is an explanatory cross-sectional view showing a moving document reading device and the like in an embodiment of the document reading device according to the present invention.
FIG. 3 is a schematic explanatory view showing an embodiment of a document reading apparatus according to the present invention.
FIG. 4 is a schematic explanatory view showing a state in which a document is sent to a document reading position by a PS roller in the embodiment of the document reading apparatus according to the present invention.
FIG. 5 is a schematic explanatory view showing a state in which the leading end of the document in FIG. 4 comes into contact with platen glass.
FIG. 6 is a schematic explanatory view showing a state in which the platen glass of FIG. 5 slides in a direction parallel to the document transport direction and stops, and the document is continuously transported.
FIG. 7 is a schematic explanatory view showing a state where the contact area between the document and the platen glass in FIG. 6 gradually decreases.
8 is a schematic explanatory view showing a state in which the end of the document in FIG. 7 is separated from the platen glass, and the platen glass returns to its original position and stops.
FIG. 9 is an explanatory diagram for explaining the reason why the platen glass in the embodiment of the document reading apparatus according to the present invention is slidable in a direction parallel to the document conveying direction.
FIG. 10 is an explanatory diagram showing a conventional technique in Japanese Patent No. 3134773.
FIG. 11 is an explanatory diagram showing a problem of the technique of FIG. 10;
[Explanation of symbols]
1 Document Plate 20 Moving Document Reader 40 Platen Glass 41 Holding Frame (Holding Member)
41A holding frame (holding member)
42 coil spring (elastic member)
MP manuscript

Claims (4)

A document reading device including a platen glass that comes in contact with the conveyed document, and an optical unit that reads image information from the document on the platen glass,
The platen glass is held in the holding member, and an elastic member is interposed between the platen glass and the holding member. Based on a pressing force of the elastic member, the platen glass is brought into contact with the document according to the presence or absence of contact with the document. A document reading device slidable in a direction substantially parallel to the document. 2. The document reading apparatus according to claim 1, wherein the platen glass is slid by the frictional force with the document being conveyed, and the pressing force of the elastic member is made smaller than the frictional force. 3. The document reading apparatus according to claim 1, wherein a slide width of the platen glass is larger than a contact area between the document and the platen glass. 4. The document reading apparatus according to claim 1, wherein cleaning members for removing stains on the platen glass are provided at both ends of the slide area of the platen glass.

Images