JPH08167974A - Image reader - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an image reading device capable of surely reading the white reference plate and improving the accuracy of the image reading start position. [Configuration] The document reading device 11 includes a contact glass 14
A first carriage that exposes a document placed on it to obtain a reflected light image from the document, a second carriage that guides the reflected light image from the first carriage to an optical lens, and an image is formed by the optical lens. And an image sensor for photoelectrically converting the captured image. A white reference plate 52 is provided on the left scale 51 for fixing the contact glass 14.
A display body (predetermined graphic pattern 56) is provided on the contact glass 14 in a region before the white reference plate 52 is read. The first means (not shown) is configured to change the position of the image reading area in the sub-scanning direction based on the read data obtained when the graphic pattern 56 provided in the predetermined area is read by the image sensor.

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 used in a copying machine or the like, and more particularly to an image reading apparatus for reading an image of a document placed on a contact glass with an image sensor.

[0002]

2. Description of the Related Art As is well known, an image reading apparatus of this kind is used in, for example, a digital copying machine. The basic configuration of the digital copying machine is the image reading device,
Generally, a printer unit having a laser beam scanning device and an automatic document feeder are provided. Here, the automatic document feeder conveys the set originals one by one, sets them on the contact glass, and discharges the originals on the contact glass after the copying is completed.

Further, the image reading apparatus includes a first carriage equipped with a light source including an illumination lamp and a reflecting mirror and a first mirror, a second carriage equipped with a second mirror and a third mirror, and each mirror of these carriages. An optical lens for forming an optical image sent via the optical lens and an image sensor such as a CCD sensor for converting the optical image formed by the optical lens into an image signal. Further, in the above-mentioned printer unit, during the copying operation, after the photoconductor drum is uniformly charged by the charging device by being rotationally driven by the driving unit, the image exposure by the digital image signal subjected to the image processing is performed by the laser beam scanning device. The electrostatic image on the photoconductor drum is transferred and developed on the sheet by the developing device.

The operation of such a digital copying machine will be described with reference to FIG. FIG. 21 is a view of the contact glass 501 seen from above, and is also an explanatory diagram in which the reading timing MSG in the main scanning direction M and the reading tamming SSG in the sub scanning direction S are also displayed. Note that the symbol LSYNC of the timing MSG is a synchronizing signal, and the symbol LGATE is a document reading range defining gate signal. Further, the code SLEAD of the timing SSG is a shading gate signal, and the code FGATE is a document reading range defining gate signal.

At the time of reading a document, first, one set document is taken out by the automatic document feeder, conveyed, and placed on the contact glass. After that, the first carriage moves forward in a direction indicated by an arrow (sub-scanning direction S) in FIG. 21 at a constant speed, and the second carriage follows the first carriage at a speed half that of the first carriage. Move forward. At the same time, as shown in FIG. 21, the main scanning direction M
To be scanned. As a result, the document on the contact glass is scanned. In this state, the original on the contact glass is illuminated by a light source or the like, and the reflected light image is guided to the optical lens via the first mirror, the second mirror, and the third mirror, and the optical lens causes the reflected light image to be displayed on the image sensor. It is imaged. This image sensor photoelectrically converts the formed reflected light image of the document into an analog image signal, and the document is read.

After reading the original, the first carriage and the second carriage return to the home position. After copying, the original on the contact glass is ejected by the automatic original feeder, and the next original set is taken out by the automatic original feeder and conveyed to be placed on the contact glass. It
In this way, the reading of the document is performed one after another. An analog image signal output from the image sensor is converted into a digital image signal by an analog / digital converter, and various image processing (binarization, multi-value conversion, floor conversion, etc.) is performed on a circuit board equipped with an image processing circuit. Keying processing, scaling processing, editing processing, etc.) are performed.

During the copying operation, in the printer section of the digital copying machine, the photosensitive drum is rotationally driven by the driving section so that it is uniformly charged by the charging device. The digital image signal image-processed by the image processing circuit is
An electrostatic image is formed on the photosensitive drum by the laser beam scanning device. Then, after the electrostatic image on the photosensitive drum is transferred to the transfer paper, the transfer paper having the transfer image is developed by the developing device and discharged onto the tray as a copy. As mentioned above, conventional digital copiers can operate to make copies of documents.

By the way, in the above conventional image reading apparatus, in order to correct the illuminance on the surface of the image sensor and the output variation of each pixel of the image sensor (hereinafter referred to as "shading correction"), as shown in FIG. Manuscript scale 5
A white reference plate 503 is provided on a part of the back surface of 02 at the upper surface position 504 of the contact glass 501. Reference numeral 505 denotes an end portion of the original scale 502, and this end portion 5
One end of the document comes into contact with 05. Further, in FIG. 22, reference numeral HP is a home position, and when starting reading, for example, the first mirror 506 of the first carriage is positioned at the home position HP.

Then, in the image reading apparatus, as shown in FIG.
As shown in, the first carriage is at the home position H.
It starts to move in the sub-scanning direction S from P, and it is determined that a predetermined distance Ls has passed from the home position HP before reading a document placed on the contact glass 501, and the shading gate signal SLEAD is set to a predetermined width. By opening only DS, the white reference plate 503 has a constant width DS
Is read by the image sensor. In this way, the analog image signal obtained by reading with the image sensor is given to the image processing circuit to perform shading correction. Also,
In the image reading device, the distance Lf from the home position HP
By opening the area determination gate signal FGATE that determines the original reading area by the width W (the size of the original), the reflected light image of the original is given to the image sensor to read the original. There is.

The width W in FIG. 22 is the original size,
It depends on the size of the transfer paper, the scaling factor, etc. The home position HP (reference position as a reference in the sub-scanning direction S) is determined by detecting a specific position of the first carriage or the second carriage with a sensor such as a photo interrupter. Further, the image reading start position (distance Lf from the home position HP) can be adjusted in consideration of variations in the positions of the document scale 502 and the sensor (photo interrupter) for detecting the home position HP, component accuracy, and the like.

On the other hand, in the conventional image reading apparatus, the reading start position of the image in the main scanning direction M is, as shown in FIG. 23, the positions of the back scale 507, the optical axis of the lens 508, and the CCD sensor 509 as an image sensor. It depends on the relationship. The image reading area varies depending on the precision of each of the above components and the precision of the components that form each component. The image reading area is also displaced due to the inclination of the first mirror 506, the second mirror 512, and the third mirror 513. Therefore, C
The CD sensor 509 can be moved and adjusted in the direction of arrow Q in the figure, and after the reader is assembled, the image of the end portion (original setting reference) 510 of the left scale 507 is formed on a predetermined pixel α on the CCD sensor 509. CCD sensor 509 as imaged
Is adjusted or the position of the gate signal that determines the effective image area in the main scanning direction is changed to adjust the image reading area in the main scanning direction M. Incidentally, reference numeral 51
1 is a fixed base of the CCD sensor 509.

[0012]

As described above, in the conventional image reading apparatus, the reading start position of the white reference plate (the distance Ls from the home position HP) is the position of the home position sensor such as the photo interrupter. In order to determine the standard, the position variation of the home position sensor itself, the position detection accuracy of the carriage by the home position sensor, the position accuracy between the home position sensor and the white reference plate, the temperature change, and the influence of the device installation surface are considered. There is a drawback that the reading start position of the white reference plate changes due to the positional deviation of each component when received.

Therefore, it is necessary to set the effective range of the white reference plate to be sufficiently wider than the reading region S so that the reading region S of the white reference plate does not deviate from the effective range of the white reference plate, or the reading of the white reference plate is performed. Start position (home position H
It became necessary to adjust the distance Ls from P). As a solution to the above-mentioned problem, paying attention to the fact that the position accuracy can be secured because there are few components between the original scale and the white reference plate, and the reading start position of the white reference plate is set to the image reading start position. It is conceivable that the image reading device L can be determined based on the user's convenience.
When f is changed, the reading position of the white reference plate is also displaced at the same time.

Similarly to the reading start position of the white reference plate, the original reading start position (distance Lf from the home position HP) is determined based on the position of the home position sensor, and therefore the position of the home position sensor itself varies. The carriage position detection accuracy by the home position sensor, the position accuracy between the home position sensor and the document scale, and when the temperature change or the installation surface of the device affects the position of each component There arises a problem that the reading start position fluctuates or shifts. On the other hand, in the above conventional image reading apparatus, the reading start position of the document in the main scanning direction is
Since it is determined by the inner scale, the optical axis of the lens, and the positional relationship of the CCD sensor, there is a problem in that the image reading area varies depending on the precision of each of the above components and the precision of the components that form each component.

Further, in the above image processing apparatus, the image reading area shifts due to the inclination of the first mirror, the second mirror, and the third mirror, so that the CCD sensor can be moved and adjusted, and the left scale is assembled after the reading apparatus is assembled. The position of the gate signal that adjusts the CCD sensor position and determines the effective image area in the main scanning direction so that the image at the edge (reference of the original) of the image is formed on a predetermined pixel on the CCD sensor. However, there is a drawback in that the image reading area in the main scanning direction must be adjusted, for example, by changing. Further, in the image processing device, when the temperature is changed or the device installation surface is influenced even after the assembly and adjustment, the image reading area of the image is displaced or fluctuated due to the positional deviation of each component. Occurs.

Therefore, an object of the present invention is to provide an image reading apparatus which solves the above-mentioned problems, enables reliable reading of the white reference plate, and improves the accuracy of the image reading start position. . Further, according to the present invention, the adjustment work in the manufacturing process is reduced by determining the image reading area in the main scanning direction based on the data from the image sensor corresponding to the predetermined position. It is an object of the present invention to provide an image processing apparatus in which the fluctuation of the image reading area of the above is reduced.

[0017]

In order to achieve the above object, an image processing apparatus according to the invention of claim 1 exposes a document placed on a contact glass, and a reflected light image from the document is exposed. In the image reading device, a first carriage for obtaining the above, a second carriage for guiding a reflected light image from the first carriage to an optical lens, and an image sensor for photoelectrically converting an image formed by the optical lens, It is characterized in that a means for changing the reading position of the image reading area in the sub-scanning direction is provided by the read data obtained when the display provided in the predetermined area is read by the image sensor.

In order to achieve the above object, an image processing apparatus according to a second aspect of the present invention includes a first carriage that exposes a document placed on a contact glass and obtains a reflected light image of the document. An image reading apparatus including a second carriage for guiding a reflected light image from the first carriage to an optical lens and an image sensor for photoelectrically converting an image formed by the optical lens, and a display member provided in a predetermined area. It is characterized in that means for changing the reading position of the image reading area in the main scanning direction is provided based on the position-related data obtained from the read data when the image sensor is read.

The display according to the invention of claim 3 is characterized in that it has a predetermined graphic pattern.
The display according to the invention of claim 4 is characterized by having a predetermined density pattern. The display according to the invention of claim 5 is characterized in that it has a predetermined color pattern. Further, the predetermined area of the invention according to claim 6 is characterized in that it is an end portion on the reading start side of the contact glass or the back surface of the scale.

[0020]

In the image reading apparatus according to the first aspect of the invention,
The distance (or time) from the reference position is measured based on the read data obtained when the display provided in the predetermined area is read by the image sensor, and a predetermined correction value is added to this distance to determine the sub-scanning direction. The reading position of the white reference plate or the reading position of the document is changed. As a result, even if the image reading position is changed according to the usability of the user, the reading area of the white reference plate does not change, and it is not necessary to set the effective range of the white reference plate wider than necessary.

According to the second aspect of the present invention, position-related data obtained from the read data when the display body provided in the predetermined area is read by the image sensor (for example, a predetermined graphic pattern is displayed at a predetermined pixel position of the image sensor). Based on the obtained reading time or reading distance data), the amount of deviation from the ideal reading position is obtained, and the reading position of the image reading area in the main scanning direction can be changed according to this amount of deviation. . According to the third aspect of the invention, the display body is formed into a predetermined graphic pattern, for example, N of the alphabet, thereby facilitating the formation of the read data.

Further, in the invention of claim 4, the display body is formed with a predetermined density pattern, for example, the oblique sides of the white triangle and the black triangle are combined to facilitate the formation of the read data. In the invention according to claim 5,
By forming the display body into a predetermined color pattern, for example, a combination of the hypotenuses of the white triangle and the blue triangle, the read data can be easily formed. Further, in the invention according to claim 6, the predetermined region is arranged so as to be the reading start side end portion of the contact glass or the back surface of the scale. Therefore, when the contact glass or the like is removed, the image reading start position in the scanning direction does not shift after the reassembly.

[0023]

The present invention will be described below with reference to the illustrated embodiments. 1 to 3 are views for explaining a digital copying machine applied to an embodiment of an image reading apparatus according to the present invention, and FIGS. 4 to 14 are for explaining a first embodiment of the present invention. FIG. First, a digital copying machine to which the embodiment is applied will be described with reference to FIGS. 1 to 3, and then the first embodiment will be described with reference to FIGS. 4 and 5.

<Structure of Digital Copier> FIG. 1 is an overall block diagram of the copier, FIG. 2 is an enlarged view of an image reading device of the copier, and FIG. 3 is an enlarged view of the printer section of the copier. FIG. 1, the digital copying machine is roughly composed of a document reading device 11, a printer unit 12 having a laser beam scanning device, and an automatic document feeding device 13. Here, the automatic document feeder 13
Is configured to convey the set originals one by one, set them on the contact glass 14, and eject the originals on the contact glass 14 after copying is completed.

As shown in FIG. 2, the document reading device 11 includes a first carriage A equipped with a light source including an illumination lamp 15 and a reflecting mirror 16 and a first mirror 17, a second mirror 18 and a third mirror 19. And a color filter 20 for filtering the reflected light image sent from the second carriage B.
An optical lens 21 for forming a reflected light image passing through 0,
An image sensor (CCD sensor) 22 for converting the reflected light image formed by the optical lens 21 into an analog image signal;
The circuit board 23 is provided with an analog / digital converter and an image processing circuit for image-processing a digital image signal converted by the converter, and a cooling fan 24 for cooling the illumination lamp 15.

In the document reading device 11, when reading a document, the first carriage A moves forward at a constant speed, and the second carriage B follows the first carriage A at half the speed of the first carriage A. By moving forward, the original on the contact glass 14 is optically scanned, the original on the contact glass 14 is illuminated by the illumination lamp 15 and the reflecting mirror 16, and the reflected light image is reflected by the first mirror 17 and the second mirror 17. An image is formed on the CCD sensor 22 by the optical lens 21 via the mirror 18, the third mirror 19 and the color filter 20. Further, the CCD sensor 22 photoelectrically converts the formed reflected light image of the document to output an analog image signal,
In the circuit board 23, it is converted into a digital image signal and image processing is performed. After the image reading is completed, the first carriage A and the second carriage B move back to the home position HP position. Note that CC
As the D sensor 22, three lines of C equipped with filters of red (R), green (G) and blue (B)
A color original can be read by using a CD.

The printer section 12 also forms a photoconductor drum 25 on which an electrostatic image is formed, a charging device 26 for uniformly charging the photoconductor drum 25, and an electrostatic image on the photoconductor drum 25. A laser beam scanning device 27, a developing device 28 for developing the electrostatic image formed on the photosensitive drum 25, a transfer device 30 for transferring the visible image formed on the photosensitive drum 25 onto a transfer sheet, A separation device 31 for separating the transfer paper from the photosensitive drum 25, a cleaning device 32 for wiping off the developer remaining on the photosensitive drum 25, paper feeding devices 33 to 35, and a registration roller 3.
6, a carrying device 37 for carrying the transfer paper, a fixing device 38 for fixing the visible image transferred to the transfer paper, and a tray 39 for placing a copy.

Next, the details of the laser beam scanning device 27 will be described with reference to FIGS. 1 and 3. The laser beam scanning device 27 includes a semiconductor laser unit 40 fixed to the side surface of its housing, and a cylindrical lens 41 provided at a predetermined position on the output side of the semiconductor laser unit 40.
And a polygon mirror 42 provided at the center of one end side of the housing.
A polygon motor 43 for rotating the polygon mirror 42, an fθ lens 44 provided slightly on the polygon mirror 42 side from the substantially central position of the housing, and a reflecting mirror 45 provided on the other end side of the housing. The housing is composed of a dustproof glass 46 provided below the reflecting mirror 45, a synchronization detecting mirror 47 provided at one end of the reflecting mirror 45, and a synchronization detecting sensor 48 receiving reflected light from the synchronization detecting mirror 47. ing.

The overall operation of such a digital copying machine will be briefly described. <Original Reading Operation of Digital Copier> At the time of reading an original, first, one set original is taken out by the automatic original feeding device 13 and conveyed, and the contact glass 14 is fed.
Placed on top. After that, the first carriage A moves forward at a constant speed, and the second carriage B moves forward following the first carriage A at half the speed of the first carriage A. As a result, the document on the contact glass 14 is optically scanned. The document on the contact glass 14 is illuminated by a light source or the like, and the reflected light image is reflected by the first mirror 1.
The light is guided to the optical lens 21 via the second mirror 18, the third mirror 18, and the third mirror 19, and an image is formed on the CCD sensor 22 by the optical lens 21. The CCD sensor 22 photoelectrically converts the formed reflected light image of the document into an analog image signal, and the document is read. Then, after the reading of the document is completed, the first carriage A and the second carriage B move back to the home position HP position.

After the copying is completed, the original on the contact glass 14 is discharged by the automatic original feeder, and the next original set is taken out by one sheet and conveyed by the automatic original feeder. 14 are arranged. In this way, the reading of the document is performed one after another. The analog image signal output from the CCD sensor 22 is converted into a digital image signal by an analog / digital converter mounted on the circuit board 23, and various image processing is performed by the image processing circuit mounted on the circuit board 23. (Binarization, multi-value conversion, gradation processing, scaling processing, editing processing, etc.) are performed.

<Original Copying Operation of Digital Copying Machine> During the copying operation, in the printer section 12 of the digital copying machine, the photosensitive drum 25 is rotationally driven by the driving section so that the charging device 26 uniformly charges the photosensitive drum 25. Also, the circuit board 2
The digital image signal subjected to the image processing by the image processing circuit mounted on the image forming device 3 is converted into an electrostatic image on the photosensitive drum 25 by the laser beam scanning device 27. The operation of the laser beam scanning device 27 will be described. A laser beam emitted from a semiconductor laser in the semiconductor laser unit 40 is converted into a parallel light beam by a collimating lens in the semiconductor laser unit 40, and is provided in the semiconductor laser unit 40. By passing through the aperture, it is shaped into a light beam of a fixed shape.

This light beam is compressed by the cylindrical lens 41 in the sub-scanning direction and is incident on the polygon mirror 42. The polygon mirror 42 has an accurate polygonal shape and is driven to rotate in a fixed direction by a polygon motor 43 at a fixed speed. The rotation speed of the polygon mirror 42 is determined by the rotation speed of the photosensitive drum 25, the writing density of the laser beam scanning device 27, and the number of faces of the polygon mirror 42. The laser beam entering the polygon mirror 42 from the cylindrical lens 41 is deflected by the reflecting surface of the polygon mirror and enters the fθ lens 44.
The fθ lens 44 converts the scanning light having a constant angular velocity from the polygon mirror 42 so that the photoconductor drum 25 scans at a constant velocity, and the laser beam from the fθ lens 44 is exposed through the reflecting mirror 45 and the dustproof glass 46. An image is formed on the body drum 25. The fθ lens 44 also has a surface tilt correction function. The laser beam that has passed through the fθ lens 44 is reflected by the synchronization detection mirror 47 outside the image area and guided to the synchronization detection sensor 48. Then, a detection signal output from the synchronization detection sensor 48 provides a synchronization signal that serves as a reference for cueing in the main scanning direction.

In this way, an electrostatic image is formed on the photosensitive drum 25 by the laser beam scanning device 27. Then, the electrostatic image on the photosensitive drum 25 is transferred onto the transfer paper by the transfer device 30. afterwards,
The transfer paper is separated from the photoconductor drum 25 by the separating device 31, and then conveyed to the fixing device 38 by the conveying device 37.
The transfer paper is developed by the fixing device 38 and discharged onto the tray 39 as a copy. In addition, the photosensitive drum 2
After separating the transfer paper, the cleaning device 5 is cleaned by the cleaning device 32 to remove the residual toner. In this way, the digital copying machine makes a copy.

<Description of the First Embodiment> FIG. 4 is a perspective view showing the relationship between the contact glass, the back scale, and the left scale, which are the components of the image processing apparatus. In FIG. 4, an inner scale 50 is arranged at one end of the rectangular contact glass 14, and a left scale 51 is provided at an end orthogonal to the one end of the contact glass 14.
Is arranged. After the document is placed on the contact glass 14 on which the back scale 50 and the left scale 51 are arranged, the document is read by the scanning in the sub-scanning direction S and the scanning in the main scanning direction M. Become. Here, the scanning in the sub-scanning direction S is performed while moving the carriage from the left to the right of the contact glass 14 as shown in FIG. 4, and the scanning in the main scanning direction M is shown in FIG.
What happens from top to bottom.

5 to 7 are views for explaining the positional relationship between the contact glass and the left scale. 5 is a back view of the left scale as viewed from the back, FIG. 6 is a sectional view of the positional relationship between the contact glass and the left scale as viewed from the main scanning direction, and FIG. 7 is a plan view of the contact glass. Figure 2
And in the document reading device 11 shown in FIG. 4 to FIG.
In order to correct the illuminance on the surface of the CD sensor 22 and the output variation of each pixel of the CCD sensor 22 (shading correction), a part of the back surface of the left scale 51 at a predetermined position 54.
In addition, a white reference plate 52 is provided. Reference numeral 55 is an end portion of the left scale 51, and one end portion of the document comes into contact with the end portion 55. Also, contact glass 1
4 is a predetermined graphic pattern (for example, "N" in the alphabet) on the part that is covered by the left scale 51
6 are arranged.

FIG. 8 is a block diagram showing a control system of the document reading device 11. In FIG. 8, the document reading device 1
1 is provided with a scanner control unit 101 including, for example, a one-chip CPU (central processing unit), and the scanner control unit 101 controls the operation in the document reading device 11. This scanner control unit 101
A stepping motor 103 for moving the first carriage A and the like and a blinking circuit 105 are connected to the. The blinking circuit 105 is provided between the illumination lamp 15 and the power supply 104, and controls the blinking of the illumination lamp 15 by a blinking control signal from the scanner control unit 101.
Further, the scanner control unit 101 includes a counter 106 for counting the pulses supplied to the stepping motor 103.
And the operation panel 107 are connected. Further, the scanner control unit 101 can receive a reading start command ST given from the main body.

Further, the scanner control unit 101 has a display body (predetermined graphic pattern 56) provided in a portion (predetermined region) on the contact glass 14 which is concealed by the left scale 51 when sub-scanning is performed. ) Is read by the CCD sensor 22, the position of the image reading area in the sub-scanning direction S (for example, a shading gate signal SLE for instructing to take in shading data) is read.
There is provided a first means for changing the position of AD and the position of the area defining gate signal FGATE which defines the reading area.

Further, in the document reading device 11, a display member (predetermined graphic pattern 56) provided in a portion (predetermined region) which is covered by the left scale 51 on the contact glass 14 when main scanning is performed. ) Is read by the CCD sensor 22, and second means for changing the position of the image reading area in the main scanning direction M (original reading position) is provided by the position-related data.

The output of the CCD sensor 22 is connected to the signal processing circuit 111. The output of the signal processing circuit 111 is the analog-digital (AD) converter 1
It is connected to 12. The output of the AD converter 112 is connected to one input terminal of each of the first gate circuit 113 and the second gate circuit 114. The first gate circuit 11
The shading gate signal SLEAD is supplied from the scanner control unit 101 to the control input terminal 3 of FIG. Further, the area control gate signal F from the scanner control unit 101 is applied to the control input terminal of the second gate circuit 114.
GATE is given. The output terminal of the first gate circuit 113 is connected to the shading correction circuit 115.
It is connected to the.

The output terminal of the second gate circuit 114 is connected to the image processing circuit 116. Note that CC
D sensor 22, signal processing circuit 111, AD converter 11
2. Shading correction circuit 115 and image processing circuit 1
The operation timing of the scanner 16 is controlled by the scanner controller 101.

<Description of Operation of First Embodiment> Next, the first embodiment
The operation of this embodiment will be described based on FIGS. 1 to 8 and with reference to FIGS. The first embodiment is shown in FIG.
The determination of the position in the sub-scanning direction S will be described with reference to FIGS. 9, 10 and 11, and the position change in the main scanning direction M will be described with reference to FIGS. 5 to 10 and 12 to 14. Explaining. Referring to the drawings, FIG. 9 is a timing chart for explaining the control operation of the scanner control unit, in which the horizontal axis indicates time t and the vertical axis indicates the operation of each unit.

FIG. 10 is a timing chart showing an example of a signal obtained when a predetermined graphic pattern is read by the CCD sensor, in which the horizontal axis shows the time and the vertical axis shows the signal level. FIG. 11 is an explanatory diagram showing the relationship between the positional relationship of each element in the sub-scanning direction and the read timing.
FIG. 12 is an explanatory diagram showing the positional relationship and operation timing of each part in the main scanning direction. FIG. 13 is an explanatory diagram showing the relationship between a predetermined graphic pattern and the time of read data. FIG. 14 is a flowchart for explaining a process of correcting the position based on the relationship between the predetermined graphic pattern and the time of the read data.

[Common items for position detection in the main scanning direction M and position detection in the sub scanning direction] Read start command ST from the main body
Is given to the document reading device 11 (time t ₁ ), the scanner control unit 101 creates a reference signal (time t ₂ ), and activates the blinking circuit 105 to turn on the illumination lamp 15 (time t ₃ ). . Further, the stepping motor 103 is driven to start the movement of the first carriage A and the like (time t ₄ ). On the other hand, the scanner control unit 101 causes the counter 106 to start counting the driving pulse of the stepping motor 103 at the same time when the reference signal is generated (time t ₄ ). Then, the predetermined graphic pattern 56 (see FIGS. 6 and 7) arranged on the lower side of the left scale 51 is read before the white reference plate 52. That is, when read by the CCD sensor 22 in a state of crossing a substantially central portion of a predetermined graphic pattern (for example, “N” in the alphabet) 56 on the contact glass 14, the CCD is read.
As shown in FIG. 10, the output of a predetermined pixel of the sensor 22 is that the next “L ₂ ” is output after the time “t ₁₁ ” from the first “L ₁ ”, and the time “t ₁₂ ” elapses from this “L ₂ ”. Then "L
₃ ”will be output.

[Regarding Position Detection in Sub-scanning Direction S] When the scanner control unit 101 compares this output pattern with a pattern based on the value stored in advance and the interval of the black portion and determines that they match (in FIG. 11). , And the position indicated by the symbol HPS), and the count value of the counter 106 is read.
Thereby, the distance from the reference position HP to HPS is known. Then, after that, the scanner control unit 101 reads the value of the counter 106 and changes the distance Ls from the reference position HP so that the relationship represented by the following Expression 1 is established.

[0045]

## EQU1 ## Ls = (distance from reference signal position HP to position HPS) + a

Then, the shading gate signal SLEAD is lowered at the stage when the distance Ls (or time Ts) has passed, and is returned to the original state after the fixed distance DS (or fixed period Td) has passed. As a result, the image signal from the CCD sensor 22 is input to the shading correction circuit 115. Therefore, in the shading correction circuit 115, CC
The D sensor 22 can be corrected. Further, since the shading gate signal SLEAD rises after a certain distance DS (or a certain period Td),
The first gate circuit 113 will be closed. After that, the scanner control unit 101 reads the value of the counter 106 and determines that the distance Lf to the leading end position of the read image area has been reached when the relationship of the following Expression 2 is established.

[0047]

## EQU2 ## Lf = (distance from reference signal position HP to position HPS) + b

The scanner control unit 101 determines that the area defining gate signal FGA is satisfied when the relationship expressed by the equation 2 is established.
TE is turned off, and the area defining gate signal FGATE is set only for the reading range W determined by the operation panel 107 or the like.
Then, the area defining gate signal FGATE is raised. Therefore, while the area defining gate signal FGATE is at the low level (“L”), the video signal detected by the CCD sensor 22 is output to the signal processing circuit 111,
And the AD converter 112 and the second gate circuit 114 to the image processing circuit 116.

The first means for determining the position in the sub-scanning direction S in this embodiment is adapted to determine the position in the sub-scanning direction of the image reading area based on the read data from the CCD sensor 22. Therefore, the trouble of adjusting the image reading start position in the sub-scanning direction in the manufacturing process is eliminated. Further, the first means is based on the read data obtained when the predetermined graphic pattern (in this case, the alphabet “N”) 56 provided on the contact glass 14 is read, and the relation between the mathematical expressions 1 and 2 is obtained. Since the position for reading the white reference plate 52, the document reading position, etc. are determined so that the above condition is satisfied, the number of components involved up to the document leading end position is reduced, and the accuracy of the reading start position is improved. Further, the first means can prevent erroneous recognition by reading the predetermined graphic pattern 56.

[Regarding Position Detection in Main Scanning Direction M] In addition, the scanner control unit 101 takes in the count value of the counter 106 at the same time as creating the reference signal and reads a predetermined graphic pattern 56 at a predetermined position. It has already been described that the white reference plate 52 and the document are read so that the above-described formulas 1 and 2 are satisfied when the result of comparison with the predetermined reference pattern matches. At this time, in reading the original on each reading line in the main scanning direction M, as shown in FIG. 12, the data is read for each pixel clock from the synchronization signal LSYNC for each line, and a fixed distance Lg has elapsed from the synchronization signal LSYNC. Then, it is determined that the original reference GP has been reached, and the gate signal LGATE is raised.

When the gate signal reaches the constant reading range F, the gate signal LGATE is lowered. As a result, the original is read. As described above in the description of the sub-scanning direction S, when the predetermined graphic pattern 56 is read by the CCD sensor 22, the output signal at the predetermined pixel position of the CCD sensor 22 is the first as shown in FIG. The next “L ₂ ” is output after time t ₁₁ from “L ₁ ”, and after the time t ₁₂ has elapsed from this “L ₂ ”,
₃ ”will be output.

Here, the predetermined graphic pattern 56 and CC
The relationship with the predetermined pixel position J of the D sensor 22 is shown in FIG.
As shown in FIGS. 13A to 13C, the CCD sensor 22
Changes according to the position of. For example, as shown in FIG. 13A, when the center O of the predetermined graphic pattern 56 and the predetermined pixel position J of the CCD sensor 22 match, time t ₁₁ = time t ₁₂ is established. Further, as shown in FIG. 13B, when the center O (shown by a dotted line) of the predetermined graphic pattern 56 is located below the predetermined pixel position J of the CCD sensor 22, time t ₁₁ <time t ₁₂ is reached. To establish. further,
As shown in FIG. 13C, when the center O (shown by the dotted line) of the predetermined graphic pattern 56 is located above the predetermined pixel position J of the CCD sensor 22, time t ₁₁ > time t ₁₂ is established. become.

Therefore, the scanner control unit 101 implements the second means, and compares the pattern of the output signal of the CCD sensor 22 (see FIG. 10) with the threshold value stored in advance and the pattern based on the interval of the black portion. , And when they match, the previously measured time t ₁₁ and time t ₁₂ are taken in (step 2
01). Further, the second means in the scanner control unit 101 calculates the reading position shift amount θ in the main scanning direction M based on the time t ₁₁ and the time t ₁₂ in the figure which are position-related data (F
(T ₁₁ , t ₁₂ ); The main scanning direction deviation amount is calculated at times t ₁₁ and t ₁₂ (step 202). The second means sets a correction count of the reading position shift amount θ (step 2
03), the gate signal LGATE from the synchronization signal LSYNC
The distance Lg to the rising point (document reference position GP) is determined. As described above, the predetermined graphic pattern 56 and the predetermined reading position F are set so that the calculation F (t ₁₁ , t ₁₂ ) for obtaining the reading shift amount θ according to the position-related data (time t ₁₁ and time t ₁₂ ) exists. Can be asked.

As described above, according to the second means of this embodiment, the position of the image reading area in the main scanning direction can be determined by the read data of the CCD sensor 22, so that the position in the manufacturing process can be improved. The troublesomeness of adjusting the image reading start position in the main scanning direction is eliminated. Further, according to the second means of the present embodiment, the reading position is determined by the read data obtained when the predetermined graphic pattern 56 provided on the contact glass 14 is read, and therefore erroneous recognition is prevented. it can. Although the times t ₁₁ and t ₁₂ are used as the position-related data, the distances d ₁₁ and d ₁₂ corresponding to the times t ₁₁ and t ₁₂ may be used because the moving speed of the carriage A and the like is constant.

<Description of the Second Embodiment> FIGS. 15 and 16
Is for explaining the second embodiment of the present invention.
FIG. 15 is a plan view showing a pattern on the contact glass,
FIG. 16 is an explanatory diagram showing a pattern of the read data.

[Common Items for Position Detection in Main Scanning Direction M and Position Detection in Sub-scanning Direction S] As shown in FIG. 15, the white reference plate 52 of the original scale 51 is provided on the contact glass 14.
Predetermined light and shade pattern 57 at the position to be read in advance.
Has been arranged. This predetermined shade pattern 57 is shown in FIG.
As shown in 5, black BL and white W based on the diagonal line of the quadrangle
It consists of T and. When the CCD sensor 22 is read across substantially the center of the predetermined light and shade pattern 57, the output signal from the CCD sensor 22 has a pattern of "L" and "H" with respect to the center value, as shown in FIG. Becomes

[Regarding Position Detection in Sub-scanning Direction S] Therefore, the first means in the scanner control unit 101 is
When this pattern is compared with a pattern based on the previously stored density and width and it is determined that they match, a correction reference HPS is obtained as shown in FIG. This HPS is a reference for correcting the reading position shown in FIG.
Based on PS, the gate signal SL is set so that the above formula 1 is established.
The gate signal FGATE is generated so that EAD is formed and the above-mentioned formula 2 is established. In the first means in the second embodiment, the read data is obtained when the predetermined light and shade pattern 57 provided on the contact glass 14 is read, so that the read data is related to the tip portion 55 of the left scale 51. Since the number of parts is reduced, the accuracy of the reading start position is improved, and moreover, erroneous recognition can be prevented by reading the predetermined grayscale pattern 57.

[Regarding Position Detection in Main Scanning Direction M] In the second means in the scanner control unit 101, C
Read data at a predetermined pixel position J of the CD sensor 22 (see FIG.
6 reference), if they match as compared to the pattern as a reference to a pre-stored concentration and width reading position related data obtained from the data (time t ₁₁ and time t ₁₂₎ the reading position based on The reading deviation amount θ from the ideal position is calculated, and the gate signal LGAT is calculated from the synchronization signal LSYNC as shown in FIG.
The distance Lg to E (original reference position) is determined. In the second means of the second embodiment, time t ₁₁ and time t ₁₂ (position related data) obtained from the read data obtained when the predetermined light and shade pattern 57 provided on the contact glass 14 is read. By calculating the reading position deviation amount θ from the ideal reading position by this, the trouble of adjusting the image reading start position in the main scanning direction in the manufacturing process is eliminated, and moreover, it is erroneously recognized by reading the predetermined density. Can be prevented

<Description of Third Embodiment> FIGS. 17 to 19
Is for explaining the third embodiment of the present invention. FIG. 17 is a sectional view of the arrangement relationship of the patterns used in the third embodiment as seen from the main scanning direction.
FIG. 18 is a plan view showing an example of a pattern used in this embodiment. FIG. 19 is an explanatory diagram of read data obtained in the third embodiment, in which the horizontal axis represents time t, and the vertical axis represents output signals of the R CCD sensor, G CCD sensor, and B CCD sensor. Shows.

[Matters Common to Position Detection in Main Scanning Direction M and Position Detection in Sub-scanning Direction S] In the third embodiment, CC
The D sensor 22 is assumed to be a 3-line CCD for R, G, and B. In this case, as shown in FIGS. 17 and 18, the contact glass 14 has a predetermined color pattern 5
8 are arranged. The predetermined color pattern 58 has a specific color, and the scale is made of a gray material, or the background portion of the predetermined color pattern 58 is made of gray. The predetermined color pattern 58 includes a blue B triangle and a white W of the same size.
It is arranged so that the hypotenuses of the triangles of T are in contact with each other.

In this case, as in the second embodiment, the CCD sensor 2 for reading across the center of the predetermined color pattern 58.
As for the pixel data for R and the pixel data for G in the output of the predetermined pixel position J of 2, as shown in FIG. 19, the blue B portion becomes the “L” level, and the time t ₁₁ is obtained. Then, the white WT portion becomes the “H” level, and the time t ₁₂ is obtained. In addition, among the outputs of the predetermined pixel position J of the CCD sensor 22 which is read across the center of the predetermined color pattern 58, B
As for the pixel data for use, as shown in FIG. 19, the "H" state continues from the blue part B to the white part.

[Regarding Position Detection in Sub-scanning Direction S] Therefore, the first means of the scanner control unit 101 uses such an output pattern (see FIG. 19) as a reference on the basis of the color balance and width stored in advance. When it is determined that they match with each other, the correction reference HP is set as shown in FIG.
S is obtained. This HPS is used as the correction reference HPS of the reading position shown in FIG. 11, and the gate signal SLEAD is formed based on this reference HPS so that the above-mentioned formula 1 is satisfied,
In addition, the gate signal FGATE is set so that the above equation 2 is satisfied.
Are creating. According to the third embodiment, the predetermined color pattern 58 provided on the contact glass 14 is provided.
According to the read data obtained when reading, the number of components up to the leading end portion (original leading end position) 55 of the left scale 51 is reduced, so that the accuracy of the reading start position is improved and by reading the predetermined color. False recognition can be prevented.

[Regarding Position Detection in Main Scanning Direction M] In the second means of the scanner control unit 101, C
Read data at a predetermined pixel position J of the CD sensor 22 (see FIG.
9) is compared with a pattern based on a color and a width stored in advance, and coincides with each other, the read position of the read position is determined based on the position-related data (time t ₁₁ and time t ₁₂ ) obtained from the read data. The reading deviation amount θ from the ideal position is calculated, and the gate signal LGATE is calculated from the synchronization signal LSYNC as shown in FIG.
The distance Lg to the (original reference position) is determined.

In the second means of the third embodiment, position-related data (time t ₁₁ and time t) obtained from the read data obtained when the predetermined color pattern 58 provided on the contact glass 14 is read. From t ₁₂ ), the reading position deviation amount θ from the ideal reading position is calculated,
As a result, the troublesomeness of adjusting the image reading start position in the main scanning direction in the manufacturing process is eliminated, and moreover, erroneous recognition can be prevented by reading the predetermined color pattern.

<Description of Fourth Embodiment> FIG. 20 is a perspective view showing a fourth embodiment of the present invention. In the fourth embodiment, one of the patterns 56 to 58 shown in each of the above-described embodiments is not on the contact glass 14 but as the pattern 60 on the back surface of the left scale 51 as shown in FIG. It is arranged. That is, the pattern 60 is arranged on the back surface of the left scale 51 and in the area that is read prior to the white reference plate 52 as shown in FIG. Here, one of the patterns 60 provided on the back surface of the left scale 51 is a predetermined graphic pattern 56 such as the alphabet “N” as shown in FIG. When scanned, S in the sub-scanning direction
Position detection and position detection in the main scanning direction M are performed.

Further, another one of the patterns 60 provided on the back surface of the left scale 51 is a predetermined light and shade pattern 57 composed of, for example, a triangle of white WT and black BL as shown in FIG. When the grayscale pattern 57 is read, position detection in the sub-scanning direction S and position detection in the main-scanning direction M are performed. Further, another one of the patterns 60 provided on the back surface of the left scale 51 is a predetermined color pattern 58 composed of, for example, a triangle of blue B and white WT as shown in FIG. When the pattern 58 is read, position detection in the sub scanning direction S and position detection in the main scanning direction M are performed.

According to the fourth embodiment, the read data is obtained when the predetermined graphic pattern 56 provided on the left scale 51 is read, so that there is no constituent part up to the leading edge of the document, and thus the read data is read. The accuracy of the start position is improved, and further, by reading the predetermined graphic pattern 56, erroneous recognition can be prevented. According to the fourth embodiment,
As the read data, the deviation amount θ from the ideal read position can be calculated based on the position-related data (time t ₁₁ , t ₁₂ ) obtained when the predetermined graphic pattern 56 provided on the left scale 51 is read, so that the manufacturing process The troublesomeness of adjusting the image reading start position in the main scanning direction is eliminated.

According to the fourth embodiment, the read data is obtained when the predetermined light and shade pattern 57 provided on the left scale 51 is read, so that there is no constituent part up to the leading end position of the document and thus the read data is read. The accuracy of the start position is improved, and further, by reading the predetermined light and shade pattern 57, erroneous recognition can be prevented. According to the fourth embodiment,
As for the read data, the deviation amount θ from the ideal read position can be calculated from the position-related data (time t ₁₁ , t ₁₂ ) obtained when the predetermined light and shade pattern 57 provided on the left scale 51 is read, so that the manufacturing process The troublesomeness of adjusting the image reading start position in the main scanning direction is eliminated.

According to the fourth embodiment, the read data is obtained when the predetermined color pattern 58 provided on the left scale 51 is read, so that there is no constituent part up to the leading end position of the document, and thus the read data is read. The accuracy of the start position is improved, and by reading the predetermined color pattern 58, erroneous recognition can be prevented. According to the fourth embodiment, the read data is deviated from the ideal read position by the position-related data (time t ₁₁ , t ₁₂ ) obtained when the predetermined color pattern 58 provided on the left scale 51 is read. Since the amount θ can be calculated, the trouble of adjusting the image reading start position in the main scanning direction in the manufacturing process is eliminated.

Further, according to the fourth embodiment, the predetermined pattern 60 (predetermined graphic pattern 56,
Predetermined shade pattern 57 or predetermined color pattern 5
Since 8) is provided, when the contact glass or the like is removed by exchanging service parts or the like in the market, the image reading start position in the scanning direction does not shift after reassembling. Further, in the fourth embodiment, the predetermined pattern or the predetermined color provided on the left scale 51 is formed by two-color molding, so that the left scale 51 is provided with a mark or an accessory for generating a reference signal. Processing cost, because there is no need to add
It requires less processing time and assembly time.

[0071]

As described above, according to the first aspect of the invention, the position of the image reading area in the main scanning direction is determined by the read data obtained when the display sensor provided in the predetermined area is read by the image sensor. Since the means for changing the position is provided, the troublesomeness of adjusting the image reading start position in the sub-scanning direction in the manufacturing process is eliminated. According to the invention of claim 1,
Since the means for changing the position of the image reading area in the main scanning direction is provided according to the read data obtained when the predetermined graphic pattern is read, the number of components up to the leading edge of the document is reduced, and the accuracy of the reading start position is improved. While being improved, erroneous recognition can be prevented by reading a predetermined graphic pattern. According to the second aspect of the present invention, the means for changing the position of the image reading area in the main scanning direction based on the position-related data obtained from the read data obtained when the display body provided in the predetermined area is read by the image sensor. Since we set up
The trouble of adjusting the image reading start position in the main scanning direction in the manufacturing process is eliminated. According to the second aspect of the present invention, erroneous recognition can be prevented by reading the predetermined pattern. Further, since the display body according to the third aspect has the predetermined graphic pattern, it is possible to improve the accuracy of the image reading start position and reduce the variation. Further, since the display body according to the fourth aspect has a predetermined light and shade pattern, it is possible to improve the accuracy of the image reading start position and reduce variations. Further, since the display body of the substrate according to the fifth aspect has a predetermined color pattern, it is possible to improve the accuracy and variation of the image reading start position and reduce erroneous recognition. In addition, claim 6
Since the predetermined area described is the reading start side end of the contact glass or the back surface of the scale,
When the contact glass or the like is removed in the market by exchanging service parts or the like, the image reading start position in the scanning direction does not shift after reassembling, and the processing cost, processing time, and assembly time can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a digital copying machine according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an enlargement of a document reading device of the digital copying machine of FIG.

3 is a perspective view showing an appearance of a laser beam scanning device of the digital copying machine of FIG.

FIG. 4 is a perspective view showing arrangement positions of a contact glass, a left scale and a back scale in the first embodiment.

FIG. 5 is a perspective view showing the left scale used in the first embodiment as seen from the back surface side.

FIG. 6 is a cross-sectional view showing a relationship among a left scale, a contact glass, a white reference plate, and a predetermined graphic pattern used in the first embodiment.

FIG. 7 is a plan view showing a predetermined graphic pattern arranged on the contact glass used in the first embodiment.

FIG. 8 is a block diagram showing a control system used in the first embodiment.

FIG. 9 is a timing chart for explaining the operation of the first embodiment.

FIG. 10 is a time chart showing an image signal obtained in the first embodiment.

FIG. 11 is a timing chart showing a positional relationship among gate signals, a left scale, a predetermined graphic pattern, etc. obtained in the first embodiment.

FIG. 12 is an explanatory diagram showing a relationship with a signal of a predetermined pixel position of the CCD sensor when a predetermined graphic pattern is read in the first embodiment.

FIG. 13 is an explanatory diagram for explaining a relationship between a synchronization signal and a document reference in the first embodiment.

FIG. 14 is a flowchart showing a procedure for obtaining a main scanning position in the first embodiment.

FIG. 15 is a plan view showing an arrangement state of a predetermined shade pattern according to the second embodiment.

FIG. 16 is a timing chart showing pixel data obtained according to the second embodiment.

FIG. 17 is an explanatory diagram for explaining the positional relationship among the left scale, the contact glass, the white reference plate, and the predetermined color pattern in the third embodiment.

FIG. 18 is a plan view showing an arrangement state of predetermined color patterns according to the third embodiment.

FIG. 19 is a timing chart showing an example of image data obtained when a predetermined color pattern of the third embodiment is read.

FIG. 20 is a perspective view showing an example of a pattern provided in a predetermined region on the back surface of the left scale according to the fourth embodiment.

FIG. 21 is an explanatory diagram showing the relationship between the contact glass of the conventional document reading apparatus and the timings in the main scanning direction and the sub scanning direction.

FIG. 22 is an explanatory diagram showing the relationship between the position of each component and the gate signal in the sub-scanning direction in the conventional document reading apparatus.

FIG. 23 is an explanatory diagram showing the relationship between the position of each component in the main scanning direction, the reading range, etc. in the conventional document reading apparatus.

[Explanation of symbols]

 11 Document Reading Device 12 Printer Section 13 Automatic Document Feeding Device 14 Contact Glass 15 Illumination Lamp 16 Reflecting Mirror 17 First Mirror 18 Second Mirror 19 Third Mirror 20 Color Filter 21 Optical Lens 22 CCD Sensor (Imaging Sensor) 23 Circuit Board 24 Cooling fan 25 Photoreceptor drum 26 Charging device 27 Laser beam scanning device 28 Developing device 30 Transfer device 31 Separation device 32 Cleaning device 38 Fixing device 40 Semiconductor laser unit 41 Cylindrical lens 42 Polygon mirror 43 Polygon motor 44 fθ lens 45 Reflector 46 Dustproof Glass 47 Sync detection mirror 48 Sync detection sensor A 1st carriage B 2nd carriage 50 Back scale 51 Left scale 52 White reference plate 54 Top surface position 55 End 56 Predetermined figure pattern 57 predetermined shade pattern 58 predetermined color pattern 60 pattern 101 scanner control unit 103 stepping motor 104 power supply 105 blinking circuit 106 counter 107 operation panel 111 signal processing circuit 112 AD converter 113 first gate circuit 114 second gate circuit 115 shading correction Circuit 116 Image processing circuit

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03G 21/14 (72) Inventor Tetsuya Kimura 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (6)

[Claims] 1. A first carriage for exposing a document placed on a contact glass to obtain a reflected light image from the document, and a second carriage for guiding the reflected light image from the first carriage to an optical lens. In an image reading device including an image sensor that photoelectrically converts an image formed by the optical lens, a sub-pixel of the image reading region is obtained by reading data obtained when the display body provided in a predetermined region is read by the image sensor. An image reading apparatus comprising means for changing a reading position in a scanning direction. 2. A first carriage for exposing a document placed on a contact glass to obtain a reflected light image of the document.
An image reading apparatus including a second carriage for guiding a reflected light image from the first carriage to an optical lens, and an image sensor for photoelectrically converting an image formed by the optical lens, wherein a display body provided in a predetermined area is provided. An image reading apparatus comprising means for changing the reading position of the image reading area in the main scanning direction based on position-related data obtained from the reading data when the image sensor reads the image. 3. The image reading apparatus according to claim 1, wherein the display body has a predetermined graphic pattern. 4. The image reading apparatus according to claim 1, wherein the display body has a predetermined density pattern. 5. The image reading apparatus according to claim 1, wherein the display body has a predetermined color pattern. 6. The image reading device according to claim 1, wherein the predetermined area is an end portion of the contact glass on a reading start side or a back surface of a scale.