JPH04137969A - Picture reader - Google Patents

Abstract

PURPOSE:To acquire an accurate data of a close contact sensor at current reading by moving a white level part of a sheet member to a read position prior to read of an original and detecting a dispersion data of the contact type sensor based on a reflected light from the white level part. CONSTITUTION:A picture reader 1 sets an output of a black level part 13 to be zero when an output waveform of a contact type read sensor is an output waveform of the black level part 13 of a sheet member 10. Then the sheet member 10 is carried an when an output of the contact type read sensor 3 is an output waveform of a reflected light from a white level part 14, the output waveform is fetched as a dispersion data for shading correction. That is, a proper shading correction data is obtained without being affected of the deterioration of the contact type read sensor 3 or the effect of dirt of a platen roller 2 or the like. When the read is finished, the sheet member 10 is carried till its transparent part 15 comes to the read position, the original is carried and the usual reading of the original is implemented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device, and more particularly to an image reading device that accurately detects and corrects variations in a contact type reading sensor.

[Conventional technology]

2. Description of the Related Art Recently, in the information age, devices that handle image information, such as facsimile machines and scanner devices, have become widespread. On the other hand, in recent years, there has been a demand for smaller devices, and devices that handle such image information are also required to be smaller. Therefore, so-called contact type sensors have been widely used.

An image reading device using such a contact type sensor is disposed in close contact with a platen roller that conveys a document, and generally uses a light emitting element as a light source, and a CCD as a photoelectric conversion unit. (Charge Couple
ed Device) is used.

Therefore, there are variations in the light emitting elements and photoelectric conversion units, and it is necessary to correct this.

Therefore, in image reading devices that use conventional contact sensors, a correction sheet is read during the manufacturing stage of the image reading device, and variations in the white waveform are detected based on the white waveform output at this time. (For example, EP ROM:
Erasable Programmable Rea
dOnly Mea+ory). When reading a document, shading correction is performed based on the data in this memory. Furthermore, conventionally, when reading a document, the surface of the platen roller is made white, the platen roller is read before the document is read, and shading correction is performed based on the result of reading the platen roller.

[Problem to be solved by the invention]

However, in such conventional image reading devices, data obtained by reading a correction sheet is stored in memory at the manufacturing stage of the image reading device, and shading correction is performed based on the data in this memory, and document reading is performed based on the data in this memory. Since shading correction was sometimes performed based on the results of reading the platen roller, there was a problem in that appropriate data could not be obtained and appropriate shading correction could not be performed.

In other words, for devices that store data in memory during the manufacturing stage, even if the light source or photoelectric conversion element deteriorates due to changes over time, the data obtained at the manufacturing stage will cover these changes over time. The current reading data cannot be obtained properly. As a result, there was a problem in that appropriate shading correction could not be performed and image quality deteriorated.

Furthermore, in devices that perform shading correction by reading the platen roller, the platen roller may become dirty or have dust attached to it during use, and the dust and dirt on the platen roller may also be captured as data. Therefore, appropriate data cannot be obtained and appropriate shading correction cannot be performed. As a result, there was a problem that the image quality deteriorated.

[Purpose of the invention]

Therefore, in the present invention, a sheet member is closely attached to the platen roller, and has a belt-shaped black part and a white part formed in the axial direction of the platen roller, and a light transmission band that transmits light from a contact type reading sensor. It is placed between the mold reading sensor and moves the white part of the sheet member to the reading position before reading the document.
By detecting the dispersion data of the close-contact sensor using the reflected light from the white background area, the contact-type sensor's light source and photoelectric conversion element are not affected by deterioration due to changes over time, and the platen roller is not affected by dust or dirt. The purpose is to make it possible to obtain accurate data from the contact type sensor during the current reading without being affected, and to perform appropriate shading correction to improve image quality.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a platen roller that is rotationally driven and conveys a document, and a platen roller that is arranged opposite to the platen roller and projects light onto the document that is conveyed by the platen roller and is reflected from the reading position. a close-contact type reading sensor that reads an image by photoelectrically converting light emitted from the platen roller; A sheet member having a light transmission band that transmits light from the sheet is disposed between the platen roller and the close-contact type reading sensor, and before reading the document, a white portion of the sheet member is moved to a reading position. , detecting variation data of the contact type sensor using reflected light from the white background portion, and after detecting the variation data, moving the light transmission band to a reading position of the contact type sensor to read the document. It is a feature.

Hereinafter, a detailed description will be given based on examples.

1 to 5 are diagrams showing an embodiment of an image reading device of the present invention.

FIG. 1 is a side view of a main part of the image reading device 1. The image reading device 1 includes a platen roller 2, and the platen roller is rotationally driven by a motor (not shown). A contact type reading sensor 3 is in contact with the platen roller 2, and the contact type reading sensor 3 has a light source 5, a lens 6, a photoelectric conversion element array 7, etc. built in a case 4. The surface of the case 4 on the platen roller 2 side is a transparent member 8 made of hard glass or the like.
The light source 5 is formed of a light emitting element array or the like. The light source 5 passes through the transparent member 8 to the reading position P.
The light is projected onto the document 9 that is fed between the platen roller 2 and the platen roller 2 . The light reflected by the original 9 is irradiated onto the photoelectric conversion element array 7 through the lens 6. As the photoelectric conversion element array 7, for example, a CCD (Char
ge Couple Dev1ce) is used and is divided into a plurality of elements. The photoelectric conversion element array 7 divides incident light into a plurality of pixels, performs photoelectric conversion on each pixel, and outputs the resulting pixel data to an image processing circuit (not shown).

This image processing circuit compares pixel data with a predetermined reference value and converts it into binary data, and also performs shading correction based on variation data, which will be described later.

Further, a sheet member 10 is housed in the case 4 of the contact type reading sensor 3, and both ends of the sheet member 10 are wound around rollers 11 and 12, as shown in FIG. The sheet member 10 has a predetermined width in the axial direction of the platen roller 2, and the sheet member 10 has a black background portion 1.
3. A white background portion 14 and a transparent portion 15 are formed. A black background portion 13 and a white background portion 1 of this sheet member 10
4 is formed in a band shape extending in the width direction of the sheet member 10, and the black background portion 13 and the white background portion 14 have a predetermined width. In the black background portion 13 and the white background portion 14, the surface of the sheet member 10 on the light source side of the contact type reading sensor 3 is painted white or black. The transparent portion 15 of the sheet member 10 may be formed into a band shape having a predetermined width, or the entire sheet member 10 other than the black background portion 13 and the white background portion 14 may be formed as the transparent portion 15. Further, the transparent portion 15 may be formed by cutting the sheet member 10 to a predetermined width so that the light from the light source 5 can pass therethrough.

The rollers 11 and 12 are rotationally driven by a driving means (for example, a motor) not shown, and the sheet member is rotated by the rollers 11 and 12.
．． 12 is rotationally driven, the platen roller 2
move parallel to the axis of Therefore, the sheet member 10 is moved by the rollers 11 and 12, so that the black background portion 13, the white background portion 14, and the transparent portion 15 are sequentially located at the reading position P.

Next, the effect will be explained.

When reading an image, the image reading device 1 performs the following steps before reading the image.
First, as shown in FIG. 3, the motor for driving the sheet member is driven to move the sheet member 10 in the traveling direction of the original 9 (in the direction of the arrow in FIG. 1) (step Sl). At this time, the contact type reading sensor 3 projects light from the light source 5 to the reading position P, irradiates the photoelectric conversion element array 7 with the reflected light, and outputs the reflected light to an image processing circuit (not shown). Therefore, if the transparent portion 15 of the sheet member 10 is removed from the reading position while the sheet member 10 is being conveyed, the sheet member 10
Reflected light from the white background portion 14 or the black background portion 13 is incident on the photoelectric conversion element array 7, and the image reading device t can detect the position of the sheet member 10 based on the reflected light from the sheet member 10.

That is, the output waveform of the black background portion 13 has a small output as shown in FIG. 4, and the output waveform of the white background portion 14 has a large output as shown in FIG.

The image reading device 1 checks whether the output waveform of the contact type reading sensor 3 that has read the sheet member IO is the output waveform of the black background portion 13 (step S2), and if it is the output waveform of the black background portion 13, the image reading device 1 checks this black background portion 13. When detected, the threshold level of the image processing circuit is set so that the output of this black background portion 13 becomes O, that is, the output of all elements of the photoelectric conversion element array 7 becomes black data. After that, the sheet member 10 is further conveyed,
It is checked whether the output of the contact type reading sensor 3 is the output waveform of the reflected light from the white background portion 14 of the sheet member 10 (step S4).

When the output waveform from the white background portion 14 is detected, the conveyance of the sheet member 10 is stopped, and the output waveform from the white background portion 14 is taken in as variation data for shading correction (step 35).

When the capture of the output waveform variation data of the white background portion 14 is completed, the sheet member 10 is conveyed until the transparent portion 15 comes to the reading position (step S6), and then the document is conveyed to read the normal document. Performs the reading operation. At this time, since the transparent portion 15 of the sheet member 10 is located at the reading position P, the image of the document can be read through the transparent portion 15.

Therefore, the image processing device 1 can obtain variation data for shading correction based on the reflected light of the white background portion 14 of the sheet member 10, and can prevent deterioration of the contact type reading sensor 3 and the platen roller 2 as in the conventional case. Appropriate shading correction data can be obtained without being affected by dirt, etc. As a result, shading correction can be performed appropriately and image quality can be improved. Further, this sheet member 10 is a contact type reading sensor 3.
Since the sheet member is housed in the case 4, it is possible to prevent the sheet member from getting dirty, and more appropriate variation data for shading correction can be obtained. As a result, shading correction can be performed more appropriately, and image quality can be further improved.

FIG. 6.7 is a diagram showing another embodiment of the image reading device of the present invention. In this embodiment, a sheet member is provided outside the case of the contact type reading sensor, and the case and the platen roller are connected. It is stretched between.

In explaining this embodiment, the same components as those in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 6, the image reading device 20 has a space between the platen roller 2 and the case 22 of the contact type reading sensor 21.
A sheet member 23 is provided, and the sheet member 23 is
As shown in FIG. 7, both ends are wrapped around rollers 24,25. Further, the sheet member 23 is guided by guide rollers 26 and 27 and is supplied between the platen roller 2 and the contact type reading sensor 21, and the sheet member 23 has a black background as well as the sheet member 10 described above. part 2
8. A white background portion 29 and a transparent portion 30 are formed.

In FIG. 6, the close-contact type reading sensor 21 is equipped with a light source, a lens, a photoelectric conversion element array, etc., as in the above-mentioned close-contact type reading sensor 3, and is capable of reading an image of a document and converting the sheet member 23. Reading is performed, but the sheet member is not internally roasted. Further, the original 9 is supplied between the platen roller 2 and the contact type reading sensor 21 in the same manner as described above.

Similarly to the above, in this image reading device 20, when reading a document, the black background portion 28 of the sheet member 23 is first conveyed to the reading position P, and the sheet member 23 is positioned based on the data of the black background portion 28. At the same time, the threshold level is set so that the image becomes completely black. Also, based on the data of the white background portion 29, variation data for shading correction is taken in and shading correction is performed.

Therefore, appropriate shading correction data can be obtained without being affected by deterioration of the contact type reading sensor 3 or dirt on the platen roller 2 as in the conventional case. As a result, shading correction can be performed appropriately,
Image quality can be improved.

In each of the above embodiments, the output of the contact type reading sensor is adjusted to all black data based on the reading data of the black background part of the sheet member, so that the output of the contact type reading sensor can be made even more uniform. This can be corrected and the image quality can be further improved.

〔effect〕

According to the present invention, a sheet member having a belt-shaped black part and a white part formed in the axial direction of the platen roller and a light transmission band that transmits light from a contact type reading sensor is tightly attached to the platen roller. It is placed between the mold reading sensor and moves the white part of the sheet member to the reading position before reading the document.
Since the variation data of the contact type sensor can be detected through the reflection holes from the white background area, it is not affected by the deterioration of the light source and photoelectric conversion element of the contact type sensor due to changes over time, and it is also possible to detect dust and dirt on the platen roller. Accurate data from the contact type sensor at the current reading time can be obtained without being affected by dirt.

As a result, appropriate shading correction can be performed and image quality can be improved.

[Brief explanation of the drawing]

1 to 5 are diagrams showing one embodiment of an image reading device of the present invention. FIG. 1 is a configuration diagram of main parts of the image reading device, FIG. 2 is a perspective view of a sheet member thereof, and FIG. Figure 3 is a flowchart showing the shuding correction data acquisition process, Figure 4 is a diagram showing the output waveform of the contact type reading sensor when reading the black background part of the sheet member, and Figure 5 is the flowchart showing the data acquisition process for the sheet member. FIG. 3 is a diagram showing an output waveform of a contact type reading sensor when reading a white background portion. 6.7 is a diagram showing another embodiment of the image reading device of the present invention, FIG. 6 is a configuration diagram of the main parts of the image reading device, and FIG. 7 is a perspective view of the sheet member. ■, 20... Image reading device, 2... Platen roller, 3.21... Contact type reading sensor, 4.22...
... Case, 5 ... Light source, 6 ... Lens, 7 ... Photoelectric conversion element array 8 ... Transparent member, 9 ... ...Manuscript, 10.23...Sheet member, 11.12.24.25...Roller, 13.2
8...Black background part, 14.29...White background part, 15.30...Transparent part, 26.27...Guide roller. Substitute Patent Attorney Agagun Diagram ■ ■ Diagram Width of photoelectric conversion element array Diagram Diagram of convergence of photoelectric conversion element array Diagram

Claims (1)

[Scope of Claims] A platen roller that is rotationally driven and conveys a document, and a platen roller that is disposed opposite to the platen roller, projects light onto the document that is conveyed by the platen roller, and photoelectrically converts the light reflected from the reading position. A contact type reading sensor that reads an image using a contact type reading sensor; A sheet member provided with a light transmission band is disposed between the platen roller and the contact type reading sensor, and prior to reading a document, a white part of the sheet member is moved to a reading position, and the white part is moved to a reading position. Image reading characterized in that variation data of a contact type sensor is detected by reflected light from the contact type sensor, and after the detection of the variation data, the light transmission band is moved to a reading position of the contact type sensor and the document is read. Device.