JP3083926B2 - Image reading device - Google Patents

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 for obtaining an image signal using a photoelectric conversion element.

[0002]

2. Description of the Related Art Today, facsimile machines, copiers and the like are widely used. These image reading apparatuses are generally constructed as shown in FIG. This image reading apparatus includes a separation roller 102 that presses a plurality of originals against a separation pressing piece 102a.
b, the originals separated one by one by the conveying roller 103b pressed against the pressing roller 103a are substantially wedge-shaped portions formed by an original platen glass 114 and a white reference unit F from the right side in the figure. Sent to. The white reference unit F has a front end of a white reference sheet 132 attached to one end of a mounting plate 131 bent substantially in a Z-shape with a double-sided tape or the like, and a rear end mounted on a movable plate 133 bent substantially in a Z-shape. It is configured to be affixed with tape or the like.

The white reference unit F, which is pressed downward by its own weight or biasing means, moves upward by the thickness of the fed document, but the document is moved by its own weight due to the weight of the white reference unit F. It is discharged to the left while being pressed against the glass stand 114. For this reason, the information surface of the original is always in contact with the surface of the original glass table 114, so that the original can be read at a stable and focused position. At this time, the front surface of the white reference unit F is flat, and the back surface of the document is in contact with the reading position E of the white reference unit F.

An image is read at the reading position E by the photoelectric conversion element.

[0005] Also, pre-scanning is performed before reading is started. The white reference is read once before the document reaches the reading position E. The read waveform is set to absolute white, and a document sent later is read (actually, complicated processing is performed based on this waveform, but omitted). This is the light source 113
To cancel output variation due to lens variation, lens angle of view, variation between image sensor bits, changes in devices due to temperature, changes in devices due to durability, etc.
This is for always reading accurately.

[0006]

However, in the above-mentioned prior art, the information written on the back surface of the document with dirt, dust, and pencils is adhered as dirt near the white reference reading position E. In addition, it was scratched because it was constantly rubbed. For this reason, there were the following disadvantages. Since a reference for reading cannot be accurately obtained, unevenness, overexposure, dirt, and the like occur in an image, particularly in halftone, and clear image information cannot be obtained. When a translucent or transparent sheet such as a tracing paper or an OHP sheet is used as a document, this dirt is read as an image, which results in a messy image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an image reading apparatus capable of obtaining a proper image without polluting a white reference reading position. Is to provide.

[0008]

In order to achieve the above object, according to the present invention, there is provided a moving light source illuminated by a light source.
Photoelectric conversion element that reads the image by the reflected light of the original
And placed on a part of the transport path where the document moves,
A transparent plate defining a position, and the transparent plate facing the transparent plate;
A guide member for pressing the document against the plate.
The part corresponding to the document reading position of the document member is the reading reference.
Image reading apparatus, the reading base of the guide member
A sheet is placed on the surface on the transparent plate side,
A sheet member is stuck.

[0009]

[0010]

[0011]

[0012]

According to the present invention, the reference value is determined based on the reading reference of the guide member.
Paste the sheet member on the upstream side of the document transport and on the transparent plate side
The original does not contact the guide member
As a result, the reading reference position does not become dirty.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. An embodiment according to the present invention applied to a facsimile apparatus of an image reading apparatus will be described.

FIG. 1 is a central sectional explanatory view of a facsimile apparatus.

First, the overall configuration of the facsimile apparatus according to the present embodiment will be described. As shown in FIG. 1, the facsimile apparatus includes a document conveying system A, an image reading system B, and an image recording system C.

An original conveying system A is a preliminary conveying roller 1 which presses a plurality of originals 1 stacked on an upper cover with a separation pressing piece 1a.
b, the sheet is separated and fed one by one by the separation roller 2b pressed against the separation pressing piece 2a, and the conveyance roller 3b pressed against the pressing roller 3a and the discharge roller 4 pressed against the pressing roller 4a.
The document is conveyed in the direction of arrow a by b and discharged to the discharge tray 5 for originals. The separation pressing pieces 1a, 2a and the pressing rollers 3a, 4a are pressed by springs and pressed against the rollers 1b, 2b, 3b, 4b.

The image information of the original 1 is conveyed from the conveying roller 3b to the discharge roller 4b while the white reference portion D and
When it is held between the original glass of the optical system, it is optically read by an image reading system B described later. The optically read image information is used as an electric signal in a facsimile mode (transmission mode) in a recording system of another machine, and in a copy mode in an image recording system C in its own facsimile apparatus.
Is configured to be transmitted.

The image recording system C uses the platen roller 8 to move the heat-sensitive roll sheet 7 accommodated in the roll holder 6 with an arrow b.
The recording sheet 9 is heated by the recording head 9 in accordance with the image signal in synchronization with the conveyance, and the recording is performed. The recorded sheet 7 is guided to the cutter 10 by the guide member and cut from the rear end of the image. It is configured to be stacked on the reversing tray 11.

Now, the structure of the image reading system B will be described in detail. As shown in FIG. 1, the image plane of the original 1 is passed through an original table glass 14 as a transparent plate by an LED array 13 which is a light source. And the reflected light (light image) is reflected by a plurality of mirrors 15a, 15b, and 15c, and through a lens 17, a photoelectric conversion element C
The CD 18 is configured to be converted to a yellow signal. Note that the image reading system B is unitized as an optical unit.

FIG. 2 is a detailed sectional view of the vicinity of the reading position E in FIG. 1. First, the configuration will be described. A white reference sheet 32 as a guide member is adhered to one end of a mounting plate 31 bent into a substantially Z shape with a double-sided tape or the like. The white reference sheet 32 is made of, for example, a polyester film having a thickness of about 100 μm, and has a color that is hard to absorb light with respect to the LED array 13 when used in white. The rear end of the white reference sheet 32 is attached to a movable plate 33 of a sheet metal which is also bent in a substantially Z-shape with a double-sided tape. On the other hand, on the surface of the white reference sheet 32, a stain prevention sheet 34 as a sheet member is stuck. As described above, the stain prevention sheet 34 forms a convex portion on the document transport upstream side.

Further, the stain prevention sheet 34 may be of any color, and it is preferable that the sheet is rich in flexibility such as polyester of about 100 μm. The sheet 34 does not need to be stuck on the entire surface, but rather has only the front end stuck, so that the flexibility is not degraded and the sticking does not cause distortion. Also, the back of the white reference sheet 32,
At the reading position E, a white sheet 36 is stuck. However, this sheet 36 is unnecessary if the white reference sheet 32 has sufficient whiteness.

In the white reference unit D, a part of the mounting plate 31 is fixed to the upper platen 35 with screws. On the other hand, the movable plate 33 at the rear end is inserted only into the notch of the upper platen 35 and is not fixed, and can be moved up and down substantially within the notch of the upper platen 35. Usually, it is pressed down by its own weight, and forms a substantially wedge-like shape following the opposing original glass table 14.

Next, the operation and operation will be described. As described above, the documents separated one by one enter the document reading system B from the right side in the drawing. This halfway conveyance is stopped, and prescan is performed. Thereafter, the conveyance is started again. The original enters a wedge shape formed by the original glass table 14 and the white reference unit D from the right side. In addition, depending on the thickness of the original
The white reference unit D, which is held only by its own weight, is pushed upward, but the original is pressed downward by the white reference unit D and is sent to the left along the original glass table 14. At this time, in the vicinity of the reading position E, the white reference sheet 32 is recessed by the thickness of the stain prevention sheet 34 and does not contact the original. Therefore, the information written on the back of the original is not stained or dusted, and the information written on the pencil is not stained and attached to the white reference reading unit, and scratches due to rubbing are also eliminated.

The white reference must be free of stains in the following respects. When a tracing paper or an OHP sheet is used as a document, the document is read by the photoelectric conversion element as a background. For this reason,
The dirt is read directly as an image and appears as dirt on the left. The image reading apparatus performs prescan depending on the model. The white reference data is directly used as the reading reference in a state where the document has not reached the reading position. Although it differs depending on the mode and model, for example, the absolute white level of each dot or the output ratio between each dot is stored, and the white level of each bit is set based on the maximum output bit in one line during actual reading. Or is determined. This is to cope with variations in light sources and sensors, changes due to temperature and time, and
This is for clear originals with a small difference in density and halftones in a clear and accurate manner. If the white reference, which is the reference, is dirty, erroneous initial data will be obtained, and the image will be significantly deteriorated.

For this reason, it is important not to stain the white standard.

On the other hand, pressing the white reference against the glass surface and the document surface has the following merits. By pressing the manuscript against the glass surface, if a lens is used, the document will be read at the in-focus position.
In the case of the reduced optical system, it is possible to read the image with the same magnification. Also, in the case of a lensless camera, it is necessary to read even if there is even a slight floating, so it is necessary. The white reference has a pre-scan white reference function as described above. Therefore, pre-scanning at a position where the document actually passes becomes more accurate as a reference, resulting in a clear image. In particular, when a light source having a small absolute light amount such as the LED array 13 or a light source having a large light amount different from the document conveyance direction is used, the light source and the reading direction have a certain angle, so that the light source is slightly away from the glass. If the position is shifted, the data becomes completely different, and the image is significantly deteriorated.

As described above, while taking advantage of the advantage that the original 1 is pressed against the original glass table 14 and that the white reference can be placed at substantially the same position as the original, it is possible to prevent the white reference reading position E, which is a disadvantage, from becoming dirty. Can be eliminated.

In the present invention, the main application is that the reading position is upstream from the reading position E based on the white reference, and the reading position is not stained because the document is pressed down. Therefore, it can also be configured with the following structure.

FIG. 3 is a sectional view showing the vicinity of the reading position E according to the second embodiment.

The configuration of the second embodiment will be described only for the points different from the first embodiment. One end of the dirt prevention sheet 34 is directly attached to the mounting plate 31 of the white reference unit D, and the movable plate 33 is attached to the back surface of the other end. In this embodiment, the surface of the movable plate 33 is used as a white reference. It is shown that the movable plate 33 is formed by a white mold or the like or a sheet metal. However, it may be painted on a sheet metal or mold of another color,
Alternatively, a thin sheet material may be attached around the reading position E of the movable plate 33.

FIG. 4 is a cross-sectional view near the reading position E, showing a reference example serving as a reference of the present invention .

Only the points different from the first embodiment are shown.
The white reference unit D has a center of rotation at the front end of the unit D formed of an integral sheet metal, and is rotatably attached to the upper platen 35 (not shown). Therefore, not the distortion in the white reference unit D, but the upper platen 35
Will operate in the up-down direction at the mounting portion. At this time, in consideration of the adhesion between the original glass table 14 and the white reference unit D, it is preferable that at least one center of rotation has a play in the vertical direction. The sheet metal is colored white by painting or pasting a sheet. The unit D may be made of another material such as a white mold.

Also, the present invention can be applied to a type which slides up and down instead of a type having a center of rotation. Further, in all the embodiments, a configuration in which a force is actively applied besides the own weight can be similarly applied.

[0034]

As described above , the reading reference of the guide member is used.
A sheet portion is provided on the surface on the transparent plate side further upstream of the document transport.
The reading standards are transparent plate originals
While keeping the document as far as possible from the
Even if you pass the paper or after passing the dirty original on the back,
Since the material does not stain, it is always possible to obtain the correct image
There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a central sectional view of a facsimile apparatus to which an image reading apparatus according to an embodiment of the present invention is applied.

FIG. 2 is a sectional view near a reading position in FIG. 1;

FIG. 3 is a sectional view near a reading position of an image reading apparatus according to a second embodiment of the present invention.

FIG. 4 is a sectional view near a reading position of the image reading apparatus according to the reference example of the present invention.

FIG. 5 is a cross-sectional view showing the vicinity of a reading position of a conventional image reading apparatus.

Claims (1)

(57) [Claims] A moving document illuminated by a light source;
A photoelectric conversion element that guides the reflected light to read an image, and a document reading position that is arranged in a part of a conveyance path where the document moves.
And a guide opposing the transparent plate and pressing an original against the transparent plate.
Comprises a de member, the guide member of the document reading corresponding portion reading groups in position
In the standard image reading apparatus, on the document conveyance upstream side from the reading reference of the guide member, and
It is characterized in that a sheet member is attached to the surface on the transparent plate side.
Image reading device.