JPH0358665A - Picture reader - Google Patents

Abstract

PURPOSE:To make a read position by a solid-state image pickup element always the same by controlling a moving means so as to adjust the read position by a CCD based on a read data for a read position detection mark scanned by the CCD. CONSTITUTION:When a white board 10 is scanned at a location Xa corresponding to the initial position of a CCD 8, a picture element number of white level signal in existence between a reference black line 30a and a tilt line 30b is counted by a CPU 14 and stored in a RAM 17 to obtain a reference picture element number. The picture signal of the CCD 8 is binarized and inputted to a line memory 31 and the CPU 14 reads the picture signal of the line memory 31 to count a white level picture element number in existence between the reference black line 30a and the tilt line 30b for a prescribed period and the number is compared with the reference picture element number stored in advance in the RAM 17. Then a stepping motor 19 is driven via a motor driver 15 to adjust the picture read position when viewing from the CCD 8. Thus, the read position by the solid-state image pickup element 8 is always made the same point.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image reading device used in facsimiles and the like.

(Prior Art) Regarding the conventional image reading device which is the background of the present invention, the fifth
This will be explained using figures.

FIG. 5 shows a schematic structure of an image reading device, in which 1 indicates an image reading section, and a document is conveyed to the image reading section 1 in the direction shown by arrow A. More specifically, the document P is fed by a paper feed roller disposed on the most upstream side in the conveyance direction and a separation bag 1. The image is then conveyed to the image reading section 1 under the action of the conveyance rollers 2.

The image reading unit 1 is provided with a contact glass 3, and below the contact glass 3 is provided an exposure lamp 4 (for example, made of a fluorescent lamp) for exposing the original P.
is exposed by the exposure lamp 4, and the image on the original P is moved to the mirror 6 and the condenser lens 7 along the path shown by the dashed line in FIG.
A solid-state image sensor (for example, consisting of a CCD element)
The light is focused on 8. In addition, above the contact glass 3,
A white plate 10 for shading correction is arranged.

The image on the document P is main scanned in a direction perpendicular to the plane of the paper shown in FIG. 5 by the self-scanning function of the CCD 8 itself, and sub-scanned by the conveyance of the document P itself. CCD8
generates an electromotive force depending on the brightness of the light corresponding to the image of the original,
By A/D converting this, it is stored in a memory or the like as a digital quantity, or transferred to the next processing step.

While the document P is being scanned in this manner, a delivery port 9 provided at the rear of the conveyance roller 2 and the contact glass 3 is
It is arranged so that the items are transported sequentially.

In the image reading device configured as described above, a tying switch S is provided between the conveyance roller 2 and the contact glass 3.
is provided.

This timing switch S causes the CCD 8 to scan the shading correction white plate 0 to determine the scanning timing for shading when performing shading correction, and also causes the CCD 8 to scan the original according to the timing of the original P. It is used to determine timing. To explain in detail, the shading scan is performed after the leading edge of the document P transported by the transport roller 2 has been transported for a predetermined time after turning on the timing switch
Before reaching the image reading position X in step 2, the white plate 10 for shedding correction is scanned by the CCD 8. Furthermore, the CCD 8 starts scanning the original after a predetermined time has elapsed since the timing switch S is turned on. During this predetermined time, the leading edge Pa of the original P is moved from the point of the timing switch S to the contact l/glass J2 by the CCD 8. The distance is determined from the relationship with the conveyance speed of the conveyance system so that the distance reaches a place that is a distance d ahead of the image reading position X. The distance d is usually set to about 1-21.

The reason why scanning by the CCD 8 is started after a certain distance d from the leading edge Pa of the document is as follows.
This is because if scanning by the CCDB is started in a hurry to reach the leading edge Pa of the original, the light from the lamp 4 will be scattered at the leading edge Pa of the original, and the part corresponding to the leading edge Pa of the original will be read as a black stripe. For this reason, it is preferable that the scanning of the CCD 8 starts from a position slightly recessed from the leading edge Pa of the document.

(Problems with the Prior Art) Incidentally, recent facsimile machines and the like may not be provided with a cooling device such as a cooling fan for reasons such as miniaturization of the entire device and cost reduction. For this reason, as the device is used continuously, heat sources installed inside the device, such as fluorescent lamps for commercial lighting of documents, thermal heads for printing images, various mokes for driving the device itself, etc. Due to the heat generated, the temperature inside the device rises to a considerably high temperature. With this temperature rise, the mounting portions of the optical components arranged in the optical path from the image reading unit 1 to the CCD 8 as described in -1- are distorted due to thermal expansion, and their mounting positions become misaligned. Sometimes.

For example, if the assembled part in which the condenser lens 7 and CCD 8 are integrated is displaced to the position shown by the dotted line in FIG.
Similarly, as shown by the two-dot chain line in FIG. 5, the image reading position of the contact lens 1 on the glass in the image reading unit 1 as seen from the CCD 8 may shift to a position such as Y. In this way, even if the image reading position shifts from X to Y, the CCD measured with the leading edge Pa of the document as a reference
Since the scan start timing of 8 does not change, when the CCD 8 starts reading the image from the position Y on the contact glass, a black line will be read at the position of the leading edge P a of the document as described in 2. This is an inconvenience when the image reading device is applied to facsimile transmission or the like, as black lines may appear on the image of the communication destination.

Further, the cause of the image reading position shifting from the X to Y position is not only the shift of the CCD 8 itself but also the rotation of the mirror 6 in the direction shown by arrow B in FIG. 5.

Furthermore, if the positional deviation of the optical components as described above is severe, the image reading position as seen from the CCD 8 may be completely off the contact glass. In such a case, the entire image will not appear on the communication destination using a facsimile machine or the like.

The disadvantage described below is that the mounting portions of optical components are distorted as the temperature inside the device increases, which affects the optical path.

In addition, recently miniaturized facsimile machines that can be used for portable use have optical components firmly attached, but the optical component mounting part may become damaged due to the posture during carrying or vibration during installation. This may cause distortion and affect the optical path.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image reading device that can always set the reading position of a solid-state image sensor at the same point to solve the above-mentioned conventional drawbacks.

(Means for Solving the Problems) The image reading device of the present invention scans an original existing within an image reading area narrower than the main scanning area using a solid-state image sensor capable of scanning the main scanning area, and In an image reading device that obtains an image signal corresponding to and a control means for controlling the moving means to adjust the reading position by the solid-state image sensor based on the read data of the mark for detecting the read position scanned by the solid-state image sensor. It is characterized by the fact that it is equipped with

(Example) Next, an example of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a schematic diagram showing the structure of an embodiment of the present invention, FIG. 2 is a front view of a reading position detection mark used in an embodiment of the present invention, and FIG. 3 is an operation of the present invention. FIG. 4 is a front view showing another embodiment of the reading position detection required mark.

As shown in FIG. 1, the image reading device according to this embodiment has substantially the same basic structure as the conventional image reading device, and
The difference from this conventional image reading device is that a mark 30 for detecting the reading position by the CCD 8 is provided, a moving stage 12 is provided for moving the position of the CCD 8, and
The point is that a control stage 13 is provided to control the movement stage 12 so as to adjust the reading position by the CCD 8 based on the read data of the reading position detection mark 30 scanned by the CD 8.

These differences will be explained in more detail.

The reading position detection mark 30 by the CCD 8 is constructed as follows.

As shown in FIG. 1, a white plate 10 for shading correction is placed on the contact glass 3 across the conveyance path 32 of the document P. The white plate 10 has a rectangular shape as shown in FIG. 2, at least one surface 10a of which is white, and is arranged in a direction perpendicular to the plane of the paper and parallel to the contact glass 3 in FIG. . Also white board 10
As shown in FIG. 2, the reading position 9 provided on the white plate 10 is attached so that the detection mark 30 is on the front side in the direction perpendicular to the paper surface of FIG.

The white plate 10 for shading correction has a main scanning area scanned by the CCD 8, and has an image reading area within this main scanning area. The image reading area corresponds to the maximum document width that can be read on the contact 1 and glass 3 of the image reading device. The reading position detection mark 30 is provided in an area within the main scanning area and adjacent to the image reading area. As shown in FIG. 1, a document conveyance path 32 is placed above the contact glass 3,
Shading correction white plate 1 provided with marks 30
0 is placed, a width direction regulating member (not shown) is provided in the conveyance path 32 so that the document is not conveyed beyond the image reading area. The method for conveying the document may be a so-called center reference method or a corner reference method, and the scanning quenching or image processing of the CCD 8 depending on the difference in method can be adjusted by the sequence timing.

10 To further explain using FIG. 2, the above-mentioned main scanning position detection mark 30 is constructed by roughly drawing two black lines on one side 10a of the white plate 10, and The reference black line 30a located on the scanning start side and drawn in the direction perpendicular to the main scanning direction is approximately 4.
The slope line 30b is slanted by 5 degrees.

This scanning of the white plate 10 is performed at the same timing as in the explanation of FIG. 5 above. That is, the leading edge P of the original P
The white plate 10 is scanned by the CCD 8 after the image a has been conveyed for a predetermined time after turning on the timing switch S and before the CCD 8 reaches the image reading position X on the contact glass 3. Of the image signals of one main scanning line read at this time, the signal of the part corresponding to the image reading area is used to correct the insufficient light amount at both ends of the exposure lamp 4 and to correct the sensitivity of each light receiving element in the CCDS. . Further, the reading position of the CCD 8 is adjusted using the signal of the area where the mark 30 is provided.

Main scanning 1 1 by the CCD 8 is performed from one end where the mark 30 is provided to the other end, so in FIG. be exposed.

Next, the movement stage 12 for moving the position of the CCD 8 is structured as follows. That is, the condenser lens 7,
The assembly consisting of the CCD 8 is attached to the support base 1B at L-1, and the support base 1B is made vertically movable, for example, in FIG. 16, by a holding means not shown in FIG. A rack 20 is attached to a part of the support stand 18, and by meshing with a pinion 21 attached to the output shaft of a stepping motor 19, rotation of the stepping motor 19 moves the support stand 18 downward. converted into linear motion. The initial position of the CCD 8 is adjusted at the time of shipment from the factory, etc., and is performed by adjusting the position of the support stand 18 so that the image reading position on the contact 1 glass as seen from the CCD 8 is the appropriate position X. .

In addition, the control stage 13 is mainly operated by the motor driver 1 based on data manually inputted from the line memories 1 2 31.
5 or transfer data from the line memory 31 to the next step (memory, etc.)
, a ROM 16 in which processing programs and the like as shown in FIG. 3 are written in advance, and an RA. It is being controlled by the M17. The CPU 14 controls the motor driver 15.
It is connected to drive the stepping motor 19 via.

In the image reading device configured in this way, the CC
The initial position of D8 is set at the time of shipment from the factory, but this can be done by adjusting the position of the support base 18 of the assembly consisting of the condensing lens 7 and CCD 8, so that it can be set on the contact glass 3 as seen from the CCD 8. The image reading position is the correct position
It is made to be. When the white plate 10 is main-scanned with these settings, the image reading position on the surface 10a of the white plate 10 as seen from the CCD 8 is χa (see FIG. 2).
If so, this becomes the initial position for image reading as viewed from the CCD 8 on the one surface 10a13 of the white plate 10. In addition to setting the initial position of the assembly consisting of the condenser lens 7 and CCD 8, the CCD 8 main scans the white plate 10, thereby obtaining an image signal corresponding to one line. In this image signal, there is a slight white signal on the main scanning start side, and a black signal is obtained in a portion corresponding to the reference black line 30a. Then, when scanning is performed further, the slope line 30b
A white signal corresponding to the width up to this point, a black signal when the slope line 30b is crossed, and a self-signal in all subsequent image reading areas are obtained. In this way, the white plate 10 is placed at a location corresponding to the initial position of the CCD 8 (image reading position is Xa).
When scanning, the number of pixels of the self-signal existing between the reference black line 30a and the slope line 30b is counted by the CPU 4 and stored in the RAMI 7, and this number of white pixels is counted by the CCD.
The standard number of pixels at the appropriate position is 8.

For example, if the image reading device is used continuously for a long time and the image reading position on the white plate 10 shifts upward from Xa in FIG. 2, then the white plate is scanned at the shifted position. When you do this, the reference black line 30
It is detected that the image reading position has shifted because the number of self-pixels existing between a and the slope line 30b has decreased from the reference number of pixels. Also, on the contrary, the image reading position is
If there is a downward shift from a in FIG. 2, the number of self-pixels will increase more than the reference number of pixels, and a shift in the image reading position will be detected.

Here, to explain in more detail the control procedure centered on the above-mentioned control means 13, the structure of 1,000 control stages 13 or,
Image signals from the CCD 8 are manually input to the CPU 14 via a line memory 31. That is, C
The image signal of CD8 is binarized and input to the line memory 31. The CPU 14 reads the image signal from the line memory 31, counts the number of white pixels existing between the reference black line 30a and the slope line 30b at a predetermined time, and calculates the R. It is compared with the reference pixel number stored in AM17. At this time, since the CCD 8 is also scanning the image reading area, the CPU 14 can perform the shading correction using the image signal of this area. If the reference pixel number and the white pixel number deviate by an unacceptable amount, the image reading position on the white plate 10 also deviates considerably from χa, so the size of the reference pixel number and the white pixel number is Make a comparison of
After determining the motor driving direction and motor driving amount, the stepping motor 19 is driven via the motor driver I5, and the image reading position as seen from the CCD 8 is adjusted.

In this case, it is preferable that the CPU 14 adjusts the reference pixel number to have a range so that even if the number of white pixels is not exactly equal to the reference pixel number, a certain amount of difference is allowed.

By the way, as mentioned above, the reference black line 30a and the slope line 3
The timing for counting the number of self-pixels that exist between 0b and 0b can be set as appropriate, but for example, if there are multiple originals and they are processed continuously, the temperature inside the device may also rise. Therefore, you can adjust the reading position using scanning for shading correction performed between the previous document and the next document, or if there are few documents, the start switch to start the reading operation can be set to It may be configured to be performed only once when it is turned on.

The mark 30 is also read when the CCD 8 is reading the image of the document P, but in this case, the CPU
In step 14, only the number of pixels corresponding to the area of the mark 30 from the beginning of one line is cut and transferred to the next stage of memory or the like or to a processing step.

Next, a part of the processing program stored in the ROMI 6 will be explained with reference to FIG.

First, in step SIO, it is determined whether the start switch for starting the image reading operation has been turned on, and the
If the answer is N, the process advances to step Sll. Step Sll
Before the leading edge Pa of the original P reaches the image reading position X on the contact glass 3, the main scanning area on one side 10a of the white plate 1o shown in FIG. 2 is scanned to obtain an image signal for one line. This image signal is transferred to the line memory 31 and temporarily held. Then, the CPU 4 uses the image signal of the portion corresponding to the mark 30 out of the image signal of one line stored in the line memory 31 to create a line between the reference black line 30a and the inclined line 30b. The number of white pixels is counted (step S12). Then, a shading correction operation is performed using the image signal of the portion corresponding to the remaining image reading area (step S13).

In step S14, it is determined whether the number of white pixels counted in step S12 is within the allowable reference pixel number with a certain range as described above, and if this is acceptable, there is no problem with the image reading position by the CCD 8. Since there is no image, the process advances to step S18, where the document is conveyed and the CCD 8 performs sub-scanning and main-scanning of the document to read the document image. If the next document is detected in step S19, the process returns to step Sll and the subsequent operations are repeated, and if the next document is not detected, the process ends.

If the number of white pixels is not within the allowable reference number of pixels, a comparison is made in step S15. If the number of white pixels is greater than the allowable reference pixel number, the stepping motor driving amount is determined in U14 in advance based on the relationship between the white pixel number and the reference pixel number, and the stepping motor is driven by a predetermined amount, for example. Rotate forward (step S1)
6) If the relationship between the numbers of pixels is reversed, the stepping motor is reversely rotated by a predetermined amount according to the driving amount of the stepping motor in the same manner as above (Step S]. 7)
, the process proceeds to step 318 and subsequent steps, and the same processing as described above is performed.

In this way, the CCD 8 detects that it is within the main scanning area,
In addition, by observing the reading position detection mark provided outside the image reading area, the reading position of the CCD 8 can be prevented from shifting in the sub-scanning direction.

In the embodiment described above, the mark for reading position detection is provided on a part of the white plate for shading correction, but instead of this, the mark may be provided on a part of the contact glass. In this case as well, a mark must be provided within the main scanning area of the COD and outside the image reading area.

In addition, in the second embodiment, the reading position detection mark 30
Although the reference black line 30a and the inclined line 30b are used as the reference black line 30a and the inclined line 30b, in short, it is sufficient if the number of pixels detected from the mark changes when the reading position by the CCD changes in the sub-scanning direction. .

For example, as shown in FIG. 5(a), the reference black line 30a may also be inclined with respect to the main scanning direction 40, or as shown in FIG.
), the space between the reference black line 30a and the slope line 30b may be filled out.

(Effects) Since the image reading device of the present invention is constructed as described below, it is possible to always set the reading position by the solid-state image pickup device to the same point.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the structure of an embodiment according to the present invention,
FIG. 2 is an enlarged plan view of the main part of FIG. 1, FIG. 3 is a flowchart for explaining the operation of an embodiment according to the present invention,
FIG. 4 is a front view showing another embodiment of the reading position detection mark, and FIG. 5 is a schematic diagram showing the conventional structure. 20 ・Image reading section・Contact glass・CCD ・Movement means・Control means・Reading position detection mark・Document

Claims (1)

[Claims] In an image reading device that uses a solid-state image sensor capable of scanning a main scanning area to scan an original existing in an image reading area narrower than the main scanning area and obtain an image signal corresponding to the original, a mark for detecting a reading position of a solid-state image sensor provided within the area and outside the image reading area;
A moving means for moving the position of the solid-state image sensor, and controlling the moving means so as to adjust the reading position by the solid-state image sensor based on read data of the mark for reading position detection scanned by the solid-state image sensor. An image reading device comprising a control means.