JPH04240961A - Picture reader - Google Patents

Abstract

PURPOSE:To automatically correct the deviation of an optical axis of a scanner in the main scanning direction. CONSTITUTION:An end of a guide shaft 12 guiding a scanner 1 in the subscanning direction Y is provided with a cam 24 to move the guide shaft 12 in the main scanning direction Y. A mark sheet 20 comprising a white color part 20a and a black color part 20b is adhered to an end of a transparent glass 15 forming a read window. Then the scanner 1 reads the mark sheet 20 and the scanner 1 is moved in the main scanning direction by a cam 24 and a motor 26 via the guide shaft 12 based on the read data to correct the deviation in the optical axis.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device that reads an image by moving a photoelectric conversion element (CCD sensor) having a plurality of light receiving elements in the main scanning direction in the sub scanning direction.

0002

2. Description of the Related Art FIG. 9 shows a partially cutaway perspective view of a conventional image reading device. In the figure, a scanner 1 includes a fluorescent lamp 2,
It is composed of a reading window 3, a mirror (not shown), a lens, a substrate 4 on which a CCD sensor is mounted, a detection lever 5, and the like. The belt 6 has one end fixed to the scanner 1 and is wound around a pulley 7 and a pulley 8. Gear 9 is directly connected to pulley 8. The gear 9 meshes with a motor gear 10, which is fixed to the shaft of a motor 11. Further, the scanner 1 is guided by a guide shaft 12 at one end and a guide shaft 13 at the other end, so that it can move in the direction of arrow Y and in the direction opposite to arrow Y. The home sensor 14 notifies the reference position of the scanner 1 by detecting the detection lever 5. Transparent last 15 is X
In the direction, Xw is slightly wider than the image reading width w, and in the Y direction, Y
A window is formed in the housing 16 by a length of w.

The operation of reading an image of a document placed on transparent glass 15 using the above configuration will be described.

By rotating the motor 11 in the direction of arrow a, the pulley 8 rotates in the direction of arrow b, and the belt 6
The scanner 1, which is fixed at , moves in the opposite direction of the arrow Y. When the detection lever 5 is detected by the home sensor 14, the motor 11 is stopped and the scanner 1 is stopped at the home position. Next, the fluorescent lamp 2 is turned on, the motor 11 is reversely rotated, and the reading window 3 of the scanner 1 is moved from the home position to the window end 1 where the origin 0 passes.
6a, the reading operation is started, and while moving the scanner 1 in the direction of the arrow Y, the transparent glass 15 is
Read the image of the original (not shown) above. When reading is completed, the scanner 1 is returned to the home position.

Here, as shown in FIG. 10(a), a CCD
It is necessary to align the optical axis of the sensor 1b with the window edge 16a. In FIG. 10(a), the image with the reading width w is the lens 1a.
The image is reduced in size and imaged on the CCD sensor 1b. As shown in FIG. 10(b), when a line at an angle θ is imaged with respect to the window end 16a, that is, when the optical axis is shifted by θ, the substrate 4 is rotated in the direction of arrow C. ) is generally adjusted so that it is parallel to the window edge 16a. Furthermore, when determining the reading origin X0 in the main scanning direction, the substrate 4 is moved in the direction of the arrow d for adjustment. Note that FIGS. 10(a) and 10(b) are explanatory diagrams showing the conventional reading state.

[0006]

However, in the conventional apparatus described above, the optical axis adjustment in the main scanning direction was performed manually. However, this optical axis adjustment is very delicate and takes time, and there are problems in that the adjustment errors due to individual differences among the adjustment operators are large and lack accuracy.

The present invention has been made in view of the above-mentioned problems, and its object is to automatically adjust the optical axis in the main scanning direction without relying on humans, thereby achieving accurate optical axis adjustment in a short time. The objective is to provide an excellent image reading device that performs the following tasks.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention moves a scanner equipped with a plurality of light-receiving elements arranged in the main scanning direction while being guided by a guide shaft in the sub-scanning direction to capture an image. In an image reading device, a moving means for moving a guide shaft in a main scanning direction, a mark having different two-color parts whose boundaries are parallel to the main scanning direction and arranged at an end of a reading range in a sub-scanning direction; A storage means for storing each read data read by the scanner in different two-color parts, and a transition of the optical axis of the scanner from one color part to the other color part is detected based on the read data read from the storage means. The apparatus is provided with a calculation means for calculating the amount of deviation of the optical axis, and a control means for moving the moving means by an amount corresponding to the amount of deviation determined by the calculation means.

[0009]

[Operation] First, the scanner is positioned at the reading position of one color part of the mark and the reading is performed. This read data is stored in the storage means. Next, the scanner is moved to the reading position of the other colored part of the mark and read. The calculation means calculates the amount of deviation of the optical axis of the scanner 1 based on the read data at this time and the read data stored in the storage means. Next, the control means issues a command to the moving means to move one of the guide shafts in the main scanning direction by a predetermined amount based on the calculated amount of deviation. This predetermined amount is a movement amount sufficient to eliminate the amount of deviation of the optical axis of the scanner.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. Note that elements common to each drawing are given the same reference numerals.

FIG. 1 is a partially cutaway perspective view showing a first embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a cam mechanism of the first embodiment. I will explain about it. In FIG. 1, a mark sheet 20 is attached to the upper or lower surface of the end of the transparent glass 15. As shown in FIG. The mark sheet 20 consists of a white part 20a and a black part 20b, the boundary line of which is parallel to the window edge 16a. The mark sheet 20 has a length of at least X in the direction of the arrow
It has w.

The scanner 1 is guided at one end by a guide shaft 12 and at the other end by a guide plate (not shown) so that it can move in the direction of arrow Y and in the opposite direction of arrow Y. Both ends of the guide shaft 12 are attached to the base frame 2
1a and 21b, respectively. Support hole 21c of base frame 21a into which guide shaft 12 fits
As shown in FIG. 2, it has an oval shape and is movable in the direction of arrow X and the direction opposite to arrow X. The lever 22 is rotatable around a fulcrum 22a, is biased by a spring 23 in the direction opposite to the arrow X, and presses the bush 12a fitted to the end of the guide shaft 12 in the direction opposite to the arrow X. ing. The cam 24 has one gear part 24b centered on the rotation center 24a, the other a cylindrical part 24c having a radius r eccentric by e with respect to the rotation center 24a, and has a lever part 24d at the upper part. The lever portion 24d is located at a position where it passes through the sensor 29. The cylindrical portion 24c is in contact with the bush 12a into which the guide shaft 12 is fitted, and the gear portion 24b is engaged with the motor gear 25. Motor gear 25 is fixed to the shaft of motor 26. Therefore, when the motor 26 is driven to rotate, the cam 24 rotates around the rotation center 24a,
This rotation causes the eccentric cylindrical portion 24c to move the bush 12a in the direction of arrow X. Further, the home position of the cam 24 is the position where the sensor 29 detects the lever portion 24d. On the other hand, the other end of the guide shaft 12 is freely supported by a lever 28 which is biased in the direction opposite to the arrow X by a spring 27.

As described above, the guide shaft 12 can be tilted in the direction of arrow Y by rotating the cam 24 and moving the bush 12a. By further tilting the guide shaft 12, the guide shaft 12
The scanner 1 guided by can be tilted in the direction of the arrow X. The amount of tilt of the scanner 1 is controlled by the amount of rotation of the cam 24.

In FIG. 1, the other structures are the same as those of the conventional example, so their explanation will be omitted.

Next, the electrical structure of the first embodiment will be explained with reference to FIG. FIG. 3 is a block diagram showing a first embodiment of the present invention. In the figure, the mark sheet 20 is at the window edge 1
It is separated by a distance YB from 6a and is color-coded by a color boundary line parallel to the window edge 16a. The left side of the boundary line is the white part 20a, and the right side is the black part 20b. In addition, window edge 1
6a is the reading start point in the sub-scanning direction. Furthermore, when the home sensor 14 detects the detection lever 5, the scanner 1 is located in the white area 2, which is a distance Yl away from the window 16a.
It is at position 0a.

Image signals from the scanner 1, which is composed of a lens 1a, a CCD sensor 1b, etc., are outputted to an amplifier 38. The amplifier 38 is a circuit for amplifying the image signal output from the scanner 1 to a certain level. The normalization circuit 30 includes an A/D converter 31, a latch 32, and a D/A
It is composed of a converter 33, an analog switch 34, a shading correction memory 35, a counter 36, a selector 37, and the like. The normalization circuit 30 is a circuit for correcting uneven illumination of the light source, peripheral light intensity deterioration characteristics due to the lens 1a, and the like. The A/D converter 31 compares the image signal, which is an analog signal from the amplifier 38, with an analog reference voltage Vref, and outputs the analog value of the image signal with respect to the analog reference voltage Vref as a digital value to the data line 31a. be. The latch 32 is a circuit that latches and outputs data on the data line 31a to a data bus line 35a of a shading correction memory 35, which will be described later, at the timing of the clock CL. The D/A converter 33 converts the digital value outputted from the shading correction memory 35 to the data bus line 35a into an analog signal, and converts it into an analog signal.
Output to. The analog switch 34 selects one of the peak values Vp of the analog signal from the D/A converter 33 and outputs it to the A/D converter 31 according to a command from the control circuit 40 . The output signal is the analog reference voltage V
becomes ref. The shading correction memory 35 stores the data from the latch 32 and stores the stored data in the D/D.
The data in the shading correction memory 35 can also be input and output from the control circuit 40. counter 36
is a circuit that counts up one address value at a time in accordance with the timing of the clock CL. The selector 37 selects either the address bus 40a from the control circuit 40 or the address bus 36a of the counter 36 and outputs it to the address bus line 35b of the shading correction memory 35, and latches the latch 32 at the address specified by the address bus. It stores data from the address bus, outputs data stored on the address bus to the data bus line 35a, and stores data from the control circuit 40 at the address. These selection instructions are given by the control circuit 40. The image processing section 41 performs processing such as binarization/halftone/multi-value conversion/enlargement/reduction on the normalized data output from the A/D conversion section 31, and outputs the results to a predetermined circuit.

Motor drive circuit 51 and motor drive circuit 5
2 are motors 11 respectively according to instructions from the control circuit 40.
and a circuit for driving the motor 26. Further, the sensor driver/receiver 53 and the sensor driver/receiver 54 are operated by the home sensor 1 according to instructions from the control circuit 40.
This circuit drives the home sensor 14 and the sensor 29, and notifies the control circuit 40 of the detection results of the home sensor 14 and the sensor 29. The control circuit 40 is composed of a microprocessor or the like and controls the entire circuit shown in the figure.

Next, the operation of the first embodiment having the above structure will be further explained with reference to the time chart shown in FIG.

First, the control circuit 40 includes a motor drive circuit 52.
The cam 24 is moved to a position where the sensor 29 detects the lever portion 24d of the cam 24 shown in FIG.
Park it.

Next, the control circuit 40 includes an analog switch 34
A command is issued to the selector 37 so that the peak value Vp becomes the analog reference value voltage Vref of the A/D converter 31, and a command is issued to the selector 37 to set the address bus line 36a of the counter 36.
is selected as the address bus line 35b for the shading correction memory 35. In this state, a shift pulse S
Outputs H. FIG. 4(b) shows the shift pulse SH.

When the shift pulse SH is input to the scanner 1, the CCD sensor 1b of the scanner 1 receives the shift pulse SH.
After time T0 from the input of H, the clock CL in the main scanning direction
An image of a document (not shown) is read at the same timing (as shown in FIG. 4(c)), and the image signal is serially output to the amplifier 38. Assuming that the reading position of the scanner 1 is at the white portion 20a of the mark sheet 20, the amplifier 38 outputs a white level envelope to the A/D converter 31. The A/D converter 31 outputs this envelope output to the data bus line 31a as a digital value compared to the analog reference voltage Vref, and this digital value is stored in the shading correction memory 35 via the latch 32. The output of the A/D converter 31 in this case is expressed as an analog value as shown in FIG. 4(a).

Further, assuming that the reading position of the scanner 1 is at the position of the black portion 20b of the mark sheet 20, the output of the A/D converter 31 in that case is as shown in FIG. 4(d).

Here, when the white part 20a is read, the outputs at the positions indicated by the broken lines ■ and dashed lines ■ shown in FIG. 3 become VW1 and VW2, respectively, as shown in FIG.
When reading 0b, each V
They become B1 and VB2. These values are written into the shading correction memory 35 and can be known by the control circuit 40.

The motor 1 is also connected to the motor 1 via the motor drive circuit 51.
1 to move the scanner 1 to the vicinity of the boundary line of the mark sheet 20. If the optical axis of the scanner 1 is deviated at this time, both outputs of a white portion 20a and a black portion 20b appear as shown in FIG. 4(e).

Next, the operation of checking the amount of deviation of the optical axis of the scanner 1 will be explained. First, the control circuit 40 drives the motor 11 via the motor drive circuit 51, and stops the motor 11 when the home sensor 14 detects the detection lever 5 via the sensor driver/receiver 53. As shown in FIG. 3, this position is within the white portion 20a, which is a distance Yl away from the window end 16a. The output of the A/D converter 31 at this time has the relationship shown in FIG. 4(a). At this time, the read output values VW1 and V at the positions of broken lines ■ and ■
W2 is stored as a digital value in the shading correction memory 3
5 is stored at the corresponding address.

Here, the motor 11 is further driven via the motor drive circuit 51 to move the scanner 1 in the opposite direction of the arrow Y, and the control circuit 40 detects that the read data at the position indicated by the broken line ■ or ■ is the black part 20b. The read data at the time of reading, that is, the time point when it changes to VB1 or VB2 is monitored. If the optical axis of scanner 1 is shifted from the main scanning direction,
The position of either the dashed line ■ or ■ indicates that the read data is V first.
B1 or VB2 changes.

The case where the read output at the position indicated by the broken line ■ changes from VW1 to VB1 first will be explained with reference to FIG. FIG. 5 is an explanatory diagram showing the amount of deviation of the optical axis. In the same figure, the control circuit 40 calculates and internally stores the moving distance Ya from the reference position a when the optical axis 1c of the scanner 1 first moves to the black part 20b of the mark sheet 20 at the position indicated by the broken line ■. . Move the scanner 1 further in the direction opposite to the arrow, and when the optical axis 1C is at the position indicated by the broken line ■, the black area 2
The control circuit 40 calculates and stores the distance Yb when moving to 0b. Here, since the distance X1 between the broken lines ■ and ■ is known in advance, the control circuit 40 calculates (Yb-Ya)/X1 as the amount of deviation of the optical axis 1c from the calculated value. Based on the information on the amount of deviation, the control circuit 40 drives the motor 26 via the motor drive circuit 52, rotates the cam 24, and moves the guide shaft 12 by a predetermined amount in the direction of the arrow X shown in FIG. The optical axis of the scanner 1 is made parallel to the main scanning direction. Note that the amount of rotation of the motor 26 corresponds to the amount of deviation of the optical axis, and the control circuit 40 knows in advance how much to rotate the motor 26 based on the amount of deviation of the optical axis.

[0028] At the position of the broken line ■, the read output is VW2 first.
When changing from VB2 to VB2, the amount of deviation of the optical axis can be determined in the same manner as described above, and the deviation can be corrected.

Next, a second embodiment of the present invention will be described mainly with reference to FIGS. 6 and 7. FIG. 6 is a partially cutaway perspective view showing a second embodiment of the present invention, and FIG. 7 is a block diagram showing the second embodiment.

In FIG. 6, the second embodiment of the present invention is provided with moving mechanisms at both ends of the guide shaft 12 for guiding the scanner 1 in the direction of arrow X and the direction opposite to arrow X. That is, a lever 42, a spring 43, a bush 12b, a cam 44, a gear 45, a motor 46, and a sensor 47 are attached to the base frame 21b side of the guide shaft 12 in the same way as on the base frame 21a side. Thereby, the guide shaft 12 can be moved in parallel in the main scanning direction by driving the motor 26 and the motor 46 in the same direction and by the same amount of rotation.

Further, in the second embodiment, a mark sheet 48 is attached to the end of the transparent glass 15 in the sub-scanning direction as in the first embodiment, but as shown in FIG.
8 has a black origin mark 48c in addition to a white part 48a and a black part 48b. The boundary line between the white part 48a and the black part 48b is parallel to the main scanning direction as in the first embodiment, and is located at a distance YL from the left end of the mark sheet 48 (coinciding with the window end 16a) in FIG. . Also, the position of the upper end of the origin mark 48c in the main scanning direction is the reading origin 0X0,
X0 of Y0) matches.

Further, in FIG. 7, a motor drive circuit 5 for driving the motor 46, which is newly provided in this embodiment, is shown.
A sensor driver/receiver 56 is provided which drives the sensor 3 and the sensor 47 and receives the detection results thereof, and these are controlled by the control circuit 40.

The rest of the structure is the same as that of the first embodiment, so a description thereof will be omitted.

In the second embodiment having the above structure, the operation for correcting the deviation of the optical axis of the scanner 1 is performed in the same manner as in the first embodiment. The second embodiment is characterized in that the origin position in the main scanning direction can be further corrected after the optical axis is corrected.Next, the operation of correcting the origin position in the main scanning direction will be described.

While keeping the optical axis of the scanner 1 corrected, the motor 11 is rotated via the motor drive circuit 51 so that the scanner 1 can read the origin mark 48c.
The scanner 1 is moved until the optical axis is at the position of line b shown in FIG. The image output of this line b is stored in the shading correction memory 35 in the same manner as described above. This image output is shown in FIG. 8, for example. As shown in the figure, the threshold level is set to Vs, and an output greater than this Vs is determined to be a white level, and an output smaller than Vs is determined to be an origin mark 48c (black level). The switching position from the black level to the white level from the image output data, that is, the origin mark 4
The boundary position between 8c and the white portion 48a can be determined. If it is found that this boundary position is shifted by a distance XH from the reading start point of the photoelectric conversion element 1b, then if the spectroelectric conversion element 1b, that is, the scanner 1 is moved in the main scanning direction (X direction), the photoelectric conversion element 1b The reading start point of can be made to coincide with the origin XO position. To move the scanner 1 in XH in the main scanning direction, the motor 26 and the motor 4 are
6 by the same amount corresponding to XH, rotate the cam 24 and the cam 44, and move the guide shaft 12 in the main scanning direction (
It is sufficient to translate XH by XH. With the above, the origin X0 in the main scanning direction can be aligned.

Next, the motor 11 returns the scanner 1 to the home position, that is, the line a position shown in FIG. to stop. If the motor 11 is constituted by a stepping motor, the moving distance for one step is determined in advance, so the distance Y1 from line a to line c can be determined based on the number of steps. Also, the distance YL from the origin Y0 to the line c
is predetermined at the time of manufacturing the sheet 20, so the origin Y
The distance YH between 0 and line a can be found from (YL-Y1). Therefore, when reading a document, the scanner 1
If reading is started after moving a distance YH from the home position a in the direction of arrow Y, reading will start from the origin Y0.

As explained above, according to this embodiment,
The photoelectric conversion element is arranged parallel to the main scanning direction, and reading origins in the main scanning direction and the sub-scanning direction can be determined.

The present invention is not limited to the above embodiments, but can be modified in various ways. For example, in each of the above embodiments, an image reading device using a reduction optical system using a lens has been described, but the present invention can also be applied to an image reading device using a contact type photoelectric conversion element. It goes without saying that the image reading output may be stored in a memory separate from the shading correction memory of the normalization circuit.

[0039]

As explained in detail above, according to the present invention, when the optical axis of the scanner is misaligned with respect to the main scanning direction, the amount of misalignment of the optical axis is calculated and the optical axis is automatically adjusted in the main scanning direction. The optical axis can be corrected so that it is parallel to , and the optical axis can be adjusted quickly and accurately.

Furthermore, by providing means for moving the origin mark and the scanner in parallel in the main scanning direction, it is possible to automatically set the position to the reading origin after optical axis correction.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of the present invention.

[
FIG. 2: Explanatory diagram showing the cam mechanism of the first embodiment

[Fig. 3] Block diagram showing the first embodiment of the present invention

[Fig. 4] Time chart showing the operation of the first embodiment

[Figure 5] Explanatory diagram showing the amount of deviation of the optical axis

FIG. 6 is a partially cutaway perspective view showing a second embodiment of the present invention.

FIG. 7 is a block diagram showing a second embodiment of the present invention.

[Figure 8]
Time chart showing the operation of the second embodiment

FIG. 9 is a partially cutaway perspective view showing a conventional image reading device.

FIG. 10 is an explanatory diagram showing a conventional reading state

[Explanation of symbols]

1 Scanner 12 Guide shaft 20 Mark sheet 20a White section 20b Black section 24 Cam 26 Motor 29 Sensor 35 Shading correction memory 40
Control circuit 44 Cam 46 Motor 47 Sensor 48 Mark sheet 48a White part 48b Black part 48c Origin mark X Main scanning direction Y Sub-scanning direction

Claims (2)

[Claims] Claim 1: In an image reading device that reads an image by moving a scanner equipped with a plurality of light receiving elements arranged in the main scanning direction in the sub scanning direction while being guided by a guide shaft, the guide shaft is moved in the main scanning direction. A moving means, a mark having different two-color parts whose boundary line is parallel to the main scanning direction and placed at the end of the reading range in the sub-scanning direction, and storing each read data read by the scanner in the different two-color parts. a calculating means for detecting the transition of the optical axis of the scanner from one color part to the other color part and calculating the amount of deviation of the optical axis based on the read data read from the storing means; An image reading device comprising: a control means for moving the moving means by an amount corresponding to the amount of deviation determined by the method. 2. A scanner equipped with a plurality of light receiving elements arranged in the main scanning direction is guided by a guide shaft to a first
In an image reading device that moves and reads images using a moving means, a second moving means is disposed at both ends of a guide shaft and moves the scanner in the main scanning direction, and a second moving means is provided at both ends of the guide shaft, and a second moving means is provided with a second moving means that moves the scanner in the main scanning direction. a mark arranged at the end of the reading range in the sub-scanning direction and having a boundary line parallel to the mark, a storage means for storing each read data read by the scanner in different two-color parts, and read data read from the storage means. calculation means for calculating the amount of deviation of the optical axis of the scanner and the amount of deviation of the reading start position based on the amount of deviation of the optical axis of the scanner, and control for moving the first and second moving means by a movement amount corresponding to the amount of deviation determined by the calculation means. An image reading device comprising: means.