JPH0724845Y2 - Image reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an image reading apparatus, and in particular, it is provided with a so-called book type manuscript table and a sheet type manuscript table, and one image reading unit scans documents on both manuscript tables. The present invention relates to an image reading device for reading.

(Prior Art) Conventionally, in an image reading apparatus such as a copying machine, an image reading apparatus capable of reading images of both book-type originals and sheet-type originals has been demanded. In order to avoid the trouble of manually setting the originals one by one in reading the originals, the automatic original feeding device feeds the originals to the original tray.

In this case, as an image reading apparatus, an automatic document feeder conveys a sheet-type document onto a book-type document table, temporarily stops it, moves an image reading unit to read an image, and then ejects the document, so-called copying. Machine type and sheet type document table in addition to the book type document table, the original document is fed to the sheet type document table by the automatic document feeder, and the document is read by the document reading means which is stationary while conveying the document. There is a so-called facsimile type of image reading.

However, due to the large size and high price of the automatic document feeder for the copying machine type, and the recent development of memory, the same document is duplicated even when copying (recording) multiple documents once read. Facsimile type is popular because it does not need to be read.

Such an image reading apparatus is provided with a contact glass 1, a platen roller 2, light sources 3, 4 and a guide plate 5 as a document table, as shown in FIG. The document 6 is guided by the guide plate 5 and is fed between the platen roller 2 and the contact glass 1 from an automatic document feeder (not shown). Contact glass 1
The document 6 fed between the platen roller 2 and the platen roller 2 is brought into close contact with the contact glass 1 at the contact position P between the platen roller 2 and the contact glass 1, and is conveyed and discharged by the rotation of the platen roller 2. The original 6 is irradiated with light from the light sources 3 and 4 constituting the image reading means at the point P through the contact glass 1, and the reflected light thereof constitutes the image reading means together with the photoelectric exchange means (not shown) (the light sources 3 and 4). ) And is read.

(Problems to be solved by the invention) However, in such a conventional image reading apparatus, the original fed from the automatic document feeder to the platen is closely contacted with the platen roller only by the platen roller. ,
When the document was separated from the platen roller, the document floated from the document table due to static electricity or the like that was charged during transportation, and the document reading position was only one point P. Therefore, when the image reading means is moved to the reading position of the sheet type document table and stopped to read the sheet type original after the reading operation of the book type original, the stop position of the image reading means is changed. If it goes wrong, the reading accuracy of the image deteriorates. As a result, there is a problem that the image quality deteriorates. Further, when there is a guide plate for bringing the document conveyed above the document table and on the downstream side of the platen roller into close contact with the document table, if the document is charged with static electricity during the transportation, the static electricity causes the document to be charged. Was adsorbed to the guide plate and reliably lifted from the platen, and the guide plate could not bring the document into close contact with the platen, which promotes the above-described deterioration of the image.

(Object of the Invention) Therefore, the present invention provides a conductive member for bringing the document fed from the automatic document feeder into close contact with the sheet type platen, and sets the conductive member to the document reading position. A guide plate is provided on the upstream side in the conveying direction, and further, a guide plate that guides the document conveyed by the automatic document feeder while adhering to the document table over a predetermined region is provided, and the image of the document is read between the predetermined regions. , By picking up the document conveyed to the sheet platen by the automatic document feeder, the document conveyed to the sheet platen by the automatic document feeder is directly neutralized by the conductive member, so that the document becomes electrostatic. It is possible to reliably prevent the sheet from being sucked up by the guide plate and floating from the sheet type document table, and the guide plate can guide the document while closely contacting it with the sheet type document table.
The purpose is to improve image quality.

(Structure of the Invention) In order to achieve the above object, the present invention provides a sheet type document table in which an original is automatically fed by an automatic document feeder, and a document is fed to the sheet type table by the automatic document feeder. In an image reading apparatus including an image reading unit that reads an image of an incoming original at a reading position, the image reading apparatus is provided on the upstream side in the original conveying direction with respect to the reading position, and is fed to a sheet type document table. A conductive member that is in close contact with the original and a guide plate that guides the original conveyed by the automatic original feeder while closely adhering to the sheet type original table over a predetermined area are provided.
The image reading means reads the image of the document guided by the guide plate.

Hereinafter, a detailed description will be given based on an embodiment of the present invention.

1 to 4 are views showing an embodiment of the present invention, which is applied to a scanner device.

In FIG. 1, 11 is a scanner device as an image reading device, and the scanner device 11 has an image reading means 13 housed in a case 12.

The image reading unit 13 includes light sources 14 and 15, mirrors 16, 17, and 18, a photoelectric conversion unit 19, and a drive mechanism (not shown).
Light is projected from 14 and 15 onto a document described later. The light projected on the original is reflected by the surface of the original, is incident on the mirror 16, is reflected by the mirror 16, is reflected by the mirror 17 and the mirror 18, and is guided to the photoelectric conversion unit 19. The light guided to the photoelectric conversion unit 19 is photoelectrically converted and output as an image signal. The driving means moves the light sources 14 and 15 and the mirrors 16, 17 and 18 in the sub-scanning direction (left-right direction in the drawing).

A contact glass 20 is attached to the upper part of the case 12, and the contact glass 20 forms a book type manuscript table 20a in the right part in FIG. 1 and a sheet type manuscript table 20b in the left end part in FIG. . Book type manuscript table 20a
A pressure plate 21 is provided on the upper part of the
It is used to press the book type original set in a on the book type original table 20a.

An automatic document feeder 22 is arranged on the upper left side of the case 12, and the automatic document feeder 22 includes a document table 23, a pickup roller 24, a feed roller 25, a separation roller 26, a conveyance roller 27, and a platen roller. 29, discharge rollers 30, 31, guide plate
It has 32 mag.

The pickup roller 24 is connected to the feed roller 25 by a belt 33, and the platen roller 29 and the discharge roller 31 are connected by a belt 34. Between the feed roller 25 and the separation roller 26 and the conveyance roller 27 and the conveyance roller 28,
As shown in FIG. 2, the lower guide plate 35 and the upper guide plate 36
And a lower guide plate 37 and an upper guide plate 38 are arranged between the transport roller 27, the transport roller 28 and the platen roller 29. A claw part 37a is formed at the tip of the lower guide plate 37 on the platen roller 29 side.
Are formed at equal intervals in the width direction of the document passage, for example. The claw portion 37a projects in the direction of the upper guide plate 38, and the document 39 fed from the transport rollers 27, 28 to the platen roller 29.
Together with the upper guide plate 38 in the tangential direction of the platen roller 29.

The platen roller 29 is provided on the upstream side in the conveyance direction of the document 39 with respect to the reading position and is formed of a member having good conductivity, and constitutes a conductive member. The bearings and side plates that support the platen roller 29 are also made of conductive metal. The platen roller 29 is not biased by a spring or the like, and is in contact with the book type document table 20a (contact glass 20) only by its own weight.
Therefore, the contact pressure between the platen roller 29 and the book type document table 20a becomes uniform in the axial direction (main scanning direction), and it is possible to prevent the document 39 from being skewed due to the difference in pressure balance. . The platen roller 29 brings the original 39 fed from the original table 23 into close contact with the sheet type original table 20b, and at the same time, the sheet type original table 2
After being conveyed on 0b, the guide plate 32 guides the document 39 conveyed by the platen roller 29 while closely contacting it with the sheet type document table 20b.

The discharge rollers 30 and 31 are a document tray in which the document 39 conveyed from the platen roller 29 is attached to the side of the case 12.
Discharge to 40.

Next, the operation will be described.

The scanner device 11 includes a book type document table 20a and a sheet type document table 2
It has both 0b and the original type is any book type platen.
Even when set on 20a and 20b, one image reading means 13 reads the original.

That is, normally, a book-type document is set on the book-type document table 20a.
And is pressed against the book type document table 20a by the pressure plate 21. After that, when the start button of the scanner device 11 is pressed, the image reading means 13 is moved by the driving means from the position indicated by the solid line in FIG. 1 (the reading position A) to the position indicated by the broken line on the right side (the reading position B). (Sub-scanning) is performed and the image of the document is read.

On the other hand, sheet-type originals are generally placed on the original placing table 23, and are conveyed one by one to the sheet-type original table 20b by the automatic original feeding device 22 to read the images. At this time, the operator sets the document 39 on the document table 23, switches to the sheet type mode, and presses the start button. At this time, the image reading means 13 is set at a predetermined reading position on the sheet type document table 20b side as shown in FIG. 2, and the document 39 on the document table 23 is sent to the feed roller 25 by the pickup roller 24. To be Document 39 sent to the feed roller 25
Are separated one by one by the separation roller 26, and the original 39
Then, it is sequentially sent to the transport rollers 27 and 28. The document 39 includes a lower guide plate 35, an upper guide plate 36, a lower guide plate 37, and an upper guide plate.
While being guided to the platen roller 29, it is fed to the platen roller 29 at this time, as shown in FIG. The sheet is fed between the sheet type document table 20b. The document 39 fed between the platen roller 29 and the sheet-type document table 20b is printed by the platen roller 29 as described above.
Contacting the sheet type document table 20b with a uniform pressure, the sheet is fed on the sheet type document table 20b without causing a skew. Also, since the platen roller 29, etc. are made of conductive metal, the originals will not reach up to the platen roller 29.
The static electricity charged on 39 can be removed.
The sheet is conveyed on the sheet type document table 20b in a state of being in close contact with the sheet type document table 20b without floating from the 20b. Further, the platen roller 29 removes static electricity from the document 39, so that the guide plate 3 disposed above the sheet document table 20b.
The original 39 is adsorbed to the sheet 2, and the original 39 is conveyed in a state of being closely contacted with the sheet original table 20b without being largely lifted from the sheet original table 20b. Therefore, even if the set position (reading position) of the light sources 14 and 15 fluctuates within a predetermined range (x) as shown in FIG. 4, the optical path length of the light projected from the light sources 14 and 15 onto the document 39 remains unchanged. A stable image can be received without fluctuation. That is, a stable image can be received even if the set position of the image reading means 13, especially the light sources 14 and 15 fluctuates within a predetermined area from the reading position P ₁ to the reading position P ₂ with the reading position P ₀ as the center. Therefore, the position control of the image reading means 13 can be facilitated. As a result, the scanner device
The image quality can be improved without increasing the cost.

In the above embodiment, the case where the invention is applied to the scanner device is described, but the invention is not limited to this, and the invention can be applied to a copying machine, a facsimile device, and the like.

(Effects) According to the present invention, since the document conveyed to the sheet type document table by the automatic document feeder can be directly neutralized by the conductive member, the document is attracted to the guide plate by static electricity and the sheet type document is absorbed. It is possible to reliably prevent the table from floating, and it is possible to guide the sheet type document table while closely contacting it with the guide plate. As a result, the image quality can be improved.

[Brief description of drawings]

1 to 4 are views showing an embodiment of an image reading apparatus of the present invention, FIG. 1 is a side sectional view of a scanner apparatus to which the image reading apparatus is applied, and FIG. 2 is a sheet type original thereof. FIG. 3 is an enlarged cross-sectional view of the table portion, FIG. 3 is an explanatory view of the document conveying processing operation by the platen roller, and FIG. FIG. 5 is an enlarged sectional view of a main part of a conventional image reading apparatus. 11 ... Scanner device, 13 ... Image reading means, 14, 15 ...
Light source, 16, 17, 18 …… Mirror, 19 …… Photoelectric converter, 20…
… Contact glass, 20b …… Sheet type manuscript stand, 22 ……
Automatic document feeder, 29 ... Platen roller (conductive member), 32 ... Guide plate, 39 ... Original.

Claims (1)

[Scope of utility model registration request] 1. A sheet type document table on which an original document is automatically fed by an automatic document feeding device, and an image of the document sheet fed to the sheet type document table by the automatic document feeding device is stopped at a reading position. In an image reading apparatus including an image reading unit for reading, a conductive member that is provided on the upstream side in the document feeding direction with respect to the reading position and is in close contact with a document fed to a sheet type document table; A guide plate for guiding the document conveyed by the feeding device over a predetermined area while closely contacting the sheet type document table, and reading the image of the document guided by the guide plate by the image reading means. Characteristic image reading device.