JP2002271574A - Method and device for reading image and imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a picture quality being degraded from the generation of noise occasionally, due to the influence of, e.g. interference between driving pluses for driving an imaging device exerting on the pulse, when accelerating image reading by providing a plurality of reading parts and performing image reading with a plurality of imaging devices. SOLUTION: A plurality of imaging devices for reading the different images of an original are driven by the driving pulses, having a synchronous relation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called sheet-through type image reading method for reading an image of a running document, an image reading apparatus, and an image forming system having the image reading apparatus.

[0002]

2. Description of the Related Art Sheet-through type image reading apparatuses are
Widely used in scanners, copiers, facsimile machines, etc.

[0003] In particular, a digital copying machine that has become popular recently, that is, a document image is read in pixel units, an image signal is formed in pixel units, and a dot image in pixel units is formed by using a laser or a light emitting diode in image formation. In a copying machine for forming the image forming apparatus, a sheet-through type image reading apparatus is often used.

A sheet-through type image reading apparatus has an advantage that a large number of originals can be read at a high speed. This is a reason why such a feature is frequently used in a digital copying machine. As the performance of the image forming unit has improved, the speed of the image reading device has been further increased,
There is a need for higher efficiency. In particular, there is a demand for an image reading apparatus that reads an image at high speed and with high efficiency even for a color original or a double-sided original.

To meet such needs, for example, there has been proposed an image reading apparatus in which reading units are arranged on both sides of a document conveyance path to read a front surface image and a back surface image of a document almost simultaneously. A document reading apparatus in which a plurality of reading units are arranged on one side of a document conveyance path to alternately read a plurality of conveyed documents has been proposed, for example, in Japanese Patent Application No. 2001-16137.

[0006]

In an image reading apparatus as described above, that is, an image reading apparatus in which reading sections are arranged on both sides of a document conveying path or a plurality of reading sections arranged on one side of a document conveying path, The plurality of reading units perform reading almost simultaneously with each other. That is, the reading times of the plurality of reading units overlap, and the individual reading time zones of the image sensors of the plurality of reading units partially overlap.

Each of the image sensors of the plurality of reading units is driven by a drive pulse generated from a basic clock pulse. However, when the image sensors operating simultaneously are driven by asynchronous drive pulses, the following problems occur. Occurs.

FIG. 1 shows a vertical image area signal when an image is read using two image sensors. As shown, the image area signal A1 of the first line sensor (imaging element) and the second
The image area signal A2 of the line sensor (imaging element) has a phase shifted, though there are some parts that overlap in time. Therefore, the blanking signal B2 for the second line sensor overlaps the image area signal A1 of the first line sensor,
The blanking signal B1 for the first line sensor overlaps the image area signal A2 of the line sensor. As a result, the first
The blanking signal for the second line sensor affects the image area signal A1 for the line sensor, and the blanking signal B1 for the first line sensor affects the image area signal A2 for the second line sensor, and the S / N ratio decreases. Phenomenon occurs.

When a plurality of clock pulses of the same frequency are transmitted at the same time, if these clock pulses are asynchronous, interference between the clock pulses due to radiation or the like occurs, causing unstable operation or unnecessary radiation. Problems such as instability and difficulty in EMI countermeasures arise.

FIG. 2 shows a spectrum when the waveform of a clock pulse changes due to such interference between clock pulses.

FIG. 2A shows a spectrum of a clock pulse when no interference occurs, and FIG. 2B shows a spectrum of the clock pulse when interference occurs because a plurality of circuits are arranged close to each other. It is a spectrum. As is clear from the figure, when there is interference, the amplitude of the pulse, that is, the pulse intensity H increases, and the width W of the frequency distribution increases when there is interference. Such a phenomenon causes the operation of the drive circuit for driving the image sensor to become unstable and the radiation to become unstable.

The provision of individual drive pulse generating means complicates the circuit and increases the cost.

An object of the present invention is to solve the above-mentioned problems in an image reading apparatus that reads an image using a plurality of image sensors.

[0014]

The above-mentioned object of the present invention is achieved by the following inventions.

1. An image reading method that scans a document in a main scanning direction and a sub-scanning direction by using a plurality of image sensors that read an image in pixel units and reads different images by using the plurality of image sensors, using drive pulses synchronized with each other. And driving the plurality of image sensors to perform reading.

2. 2. The image reading method according to item 1, wherein a contact image sensor is used as the image sensor.

3. 3. The image reading method according to claim 1, wherein the driving pulse is a signal generated from a basic clock pulse generated by one clock generating unit and divided for the image sensor.

4. A document table, paper feeding means for feeding the document one sheet at a time from the document table, a transport path for transporting the document, a plurality of reading units each having an image sensor and provided at a plurality of positions on the transport path An image reading apparatus comprising: a driving unit configured to drive the plurality of imaging elements with synchronized driving pulses.

5. 5. The image reading device according to the item 4, wherein the reading unit includes a contact image sensor.

6. 5. The image reading apparatus according to claim 4, wherein at least one of the reading units includes a contact image sensor, and at least another includes a reduction optical system and an image sensor.

7. The driving means is provided for each of one clock generating means for generating a basic clock pulse, one driving pulse forming means for forming a driving pulse from the basic clock pulse, and the image sensor. The image reading apparatus according to any one of the above items 4 to 6, further comprising a drive circuit that drives the image pickup device based on a pulse.

8. The image processing apparatus according to any one of 4 to 7, further comprising: a first image sensor and a second image sensor, wherein the first and second image sensors read an image on the same surface of a document. The image reading device according to claim 1.

9. It has a first image sensor and a second image sensor. The first image sensor reads an image on the first surface of the document, and the second image sensor reads an image on the second surface of the document. The image reading device according to any one of the above items 4 to 7, wherein:

10. A first image pickup element and a second image pickup element;
A single-sided reading mode for reading by an image sensor, and a double-sided reading mode for reading an image of a first surface of the document by the first image sensor and a second image of the document by the second image sensor. The image reading apparatus according to any one of the above items 4 to 7, which is characterized in that:

[11] 11. An image forming system, comprising: the image reading device according to any one of the items 4 to 10; and an image forming device that forms an image on a recording material based on image information output by the image reading device.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIGS. 3 to 10, a mechanical configuration of an image reading apparatus and an image forming apparatus according to an embodiment of the present invention will be described. FIG. 3 is a diagram showing a configuration of the image reading device according to the embodiment of the present invention.

As shown in FIG. 3, this image reading apparatus
A document table 20 on which a sheet-shaped document to be read is placed, a feed roller 19 as a paper feeding unit for feeding the document one by one from the document table 20 into the apparatus for reading, and a first conveyance for conveying the document The first pair of rollers 21, the first reading unit 11 that reads a document image on one surface S <b> 1 (the top surface in FIG. 3) of the document S sent from the first conveyance roller pair 21, and the first reading unit 11 reads the document image. A second conveying roller pair 22 for feeding the original, a large-sized conveying path 31 and a small-sized conveying path 32 for guiding the original S to the lower side of the figure by the second conveying roller pair 22,
A transport roller pair 26 provided in the middle of the large-size transport path 31 and the large-size transport path 31 or the small-size transport path 3
And a third conveying roller pair 23 that conveys the document guided and conveyed by the second conveying roller 2, and the same surface S 1 of the document S sent from the third conveying roller pair 23 that is read by the first reading unit 11. A second reading unit 12 for reading the original image on the
Transport roller pair 24 for transporting the document read by the reading unit 12 of the printer, and a discharge transport path 3 for guiding the document to be discharged.
6 and a discharge roller 25 for feeding out the document.
And a paper discharge tray 30 on which the document discharged from the paper discharge roller 25 is placed.

In the image reading apparatus, the original sent from the second transport roller pair 22 is sent through a part of the small-size transport path 32 to be sent and guided for reversing the original.
A first reversing conveyance roller 27 and a third reversing conveyance roller pair 29 that can rotate forward and reverse so as to convey the document in both the right and left directions in the figure; The original sent from the transport roller 27 is read by the first reading unit 11.
Circulating transport path 34 for guiding circulation
The document read by the second reading unit 12 and sent from the fourth transport roller pair 24 is transferred to the third reverse transport roller pair 29.
The second circulating conveyance path 35 for guiding the document to the paper feed tray 3
There is provided a reverse discharge path 37 for discharging to zero, and a second reverse conveying roller pair 28 that can rotate forward and reverse.

Further, the image reading apparatus includes a second reading unit 12
And a scanning reading unit 13. Second reading unit 12
Is a first platen glass 14, an optical system 16 that is stationary and fixed at a position directly below the first platen glass 14, and reads a document image, a reduction imaging lens 55 that forms a reduction optical system, and an image sensor 56. Many members of the second reading unit 12 also serve as the scanning reading unit 13, and the scanning reading unit 13 includes the second platen glass 15 and the second platen glass 15.
An optical system 16 ′ that scans and reads the original image of the original placed on the platen glass, a reduction imaging lens 55,
And an image sensor 56.

In reading the document S by the second reading unit 12, light is irradiated from a light source 51 onto the document image surface of the document S being conveyed on the first platen glass 14, and the reflected light is reflected by a mirror 52. , 53, and 54, and the reflected light is taken into the image pickup device 56 via the reduction image forming lens 55, whereby the original image is formed on the light receiving surface of the image pickup device 56 and read.

The scanning of the original S by the scanning and reading unit 13 is performed by moving the original placed on the second platen glass 15 and resting along the second platen glass 15 in the direction shown in FIG. By irradiating light from the light source 51 'while scanning the optical system 16', the original image is read by the image pickup device 56 composed of a line CCD thereafter in the same manner as in the second reading section.

In reading by the first reading unit 11,
In the second reading unit 12 and the scanning reading unit 13, a light source 51 composed of a halogen lamp and an image sensor 56 are used in combination, using a contact image sensor (CIS) combining a light emitting diode and an image sensor composed of a line CCD. Although a light source 51 and an image sensor 56 are used, a contact image sensor (C) in which a light emitting diode similar to the first reading unit 11 and an image sensor composed of a line CCD are combined.
IS) may be used.

Each of the transport roller pairs 21 to 25 has a motor 65.
(FIG. 9), a transport mechanism is configured, and the speed at which the document is transported can be changed by switching the rotation speed of each of the transport roller pairs 21 to 25 that are driven to rotate by the motor 65. 11 and second reading unit 1
2, the reading speed can be controlled. In order to perform such switching of the transport speed, at least the roller pairs 21 and 22 and the roller pair 2
3 and 24 can be driven independently.

The image reading apparatus shown in FIG.
In order to perform each operation as shown in FIG.
37, a transport direction switching mechanism is provided to change the transport direction of the original.
The transport direction switching member 40 arranged downstream of the second embodiment will be described with reference to FIG. 8 includes a switching guide 41 and a rotating shaft 42.
Are rotated in the rotation directions r and r ′ in the figure to switch the path, and guide the sheet-shaped document S to the large-size transport path 31 or the small-size transport path 32. Switching guide 4
When the document 1 is rotated in the direction r ′, the document S is guided to the small-size conveyance path 32 as shown in FIG. 8A, and when the document 1 is rotated in the direction r, the document S is large as shown in FIG. Transport path 31
Will be guided to. The switching operation of the switching guide 41 is performed by operating the rotating shaft 42 at an appropriate timing by a solenoid, a motor (not shown), or the like. Similarly, a transport direction switching member 4 for switching between the transport path 35 and the transport path 36.
3, and a transport direction switching member 44 for switching between the transport path 36 and the reverse discharge path 37.

FIG. 9 is a block diagram of a control system of the image reading apparatus and the image forming apparatus according to the present embodiment. Here, the solid line indicates the flow of the image data, and the broken line indicates the flow of the control signal. The image data of the document read by the first reading unit 11, the second reading unit 12, or the scanning reading unit 13 is subjected to data conversion processing by the first image processing unit 57 or the second image processing unit 58. After image processing such as correction processing, compression processing, and color image processing is performed, the image data is stored in the memory. Here, in the first image processing unit 57 and the second image processing unit 58, when the first reading unit reads with the CIS and the second reading unit reads with the image sensor, different image processing is performed. Preferably, the data is converted into the same type of image data and stored in the memory 59. When the same type of CIS is used, the first image processing unit 57 and the second image processing unit 58 may perform the same image processing.

In image formation, the image data in the memory 59 is transferred to the first image processing unit 57 or the second image processing unit 5.
8, the image data is sent to the image writing unit 60 of the image forming unit. The image writing unit 60 performs writing on the photoconductor as an electrostatic latent image, develops the electrostatic latent image, and transfers and fixes the image on a recording material to form an image.

In FIG. 9, switching of the document conveying speed, reading speed (the conveying speed at the time of reading is sometimes referred to as reading speed), and conveying direction in the image reading apparatus are shown in FIG.
FIG. 2 is a block diagram for controlling various modes and the like. The image data read by the first reading unit 11 is subjected to image processing by the first image processing unit 57, and based on the output level, whether the original image is a monochrome image or a color image, or whether the original image is A discriminating unit 61 for discriminating the size, and a transport speed at the time of reading by the second reading unit 12 based on the discrimination result, and a high first transport speed for a monochrome image. For a color image, a control unit 64 composed of a CPU or the like for controlling the document to be transported at a low second transport speed, and a rotational drive of the transport roller pairs 19 to 29 controlled in various modes. An operation display unit 6 including a motor 65 and a mode selection unit 67 that can be operated from outside the apparatus and selects a mode such as a single-sided-double-sided mode, a monochrome color mode, or a mixed mode.
6. Sensors K1 and K2 for detecting the leading and trailing edges of the original to take a reading timing, and transport direction switching members 40, 43 and 44 for switching the transport direction.

In the control system shown in FIG. 9, the document conveying speed is controlled. In order to increase the productivity in reading a document, it is preferable that the document be conveyed at a higher speed than during reading except during reading.

As an embodiment having the above-mentioned effects,
Control is performed so that the transport speed from the platen to the reading unit and the transport speed after the reading in the transport path from the reading unit to the discharge tray or the next reading unit are increased. That is, from the platen to the reading unit at a high first transport speed,
At the time of reading, the control unit 64 controls the document to be conveyed at the third conveyance speed at a high speed at the second conveyance speed of the medium speed and at the high speed third conveyance speed to the discharge tray after reading or to the next reading unit.
The first and third transport speeds, which are the high transport speeds, are preferably set to the same high transport speed in terms of simplification of control.

The above-described medium speed second conveyance speed at the time of reading indicates the conveyance speed in the case of a monochrome original, and the same second conveyance speed is applied to the case of a color original. However, it is preferable to set the fourth transport speed to a low speed because it is necessary to read sufficient image data even if color separation is more detailed in a color original.

The reading speed for discriminating an image between a monochrome document and a color document may be the fourth transport speed in the case of reading the color document, but the image data for color discrimination can be read. For this reason, it is preferable to set the medium speed to the fifth speed, which is higher than the fourth speed. In this case, the control is simplified by applying the second transport speed to the monochrome original, or by applying the first transport speed and the third transport speed which are higher if the image processing for color discrimination is possible. It is preferred to do so.

Further, the reading speed in the mixed original mode is sufficient if image data of an outer portion for discriminating the original size can be obtained.
It is preferable to set the transfer speed to In this case, the second transport speed for the monochrome document is applied, or if the image can be discriminated for size detection, the higher first transport speed and the third transport speed are applied to simplify the control. Is preferred.

The first to sixth transport speeds are, for example, a first transport speed of 800 mm / sec and a second transport speed of 40 mm.
0 mm / sec, the third transport speed is 800 mm / sec, the fourth transport speed is 300 mm / sec, and the fifth transport speed is 400 m
m / sec and the sixth transport speed may be 400 mm / sec.

In FIG. 9, a mode selection section 67 of an operation display section 66 comprising a liquid crystal touch panel or the like has a duplex mode for reading a document image of a duplex document, a color mode for reading a color document image of a color document, and a mixed document. The mode can be set by selecting the mixed mode for reading the document image by detecting the document size for each document. In addition, each mode may be provided on the operation display unit 66 so that the single-sided mode, the monochrome mode, and the same original size mode can be selected in addition to the above-described modes, but the duplex mode is not selected by default setting. In this case, it is preferable that the single-sided mode be selected, the monochrome mode be selected when the color mode is not selected, and the same original size mode be selected and set when the mixed mode is not selected.

When the duplex mode is selected and set by the mode selector 67, the controller 64 controls the motor 65 for driving each transport roller so as to transport the document corresponding to the duplex document. I do. When the duplex mode is not selected by default, the motor 65 for driving each transport roller is controlled so as to transport a document corresponding to a one-sided document.

When the color mode is selected by the mode selecting section 67, the control section 64 drives each transport roller at the fourth transport speed during reading so that the transport speed corresponds to the color original. An image discrimination is performed to control the motor 65 and each part and to determine whether the document is a color document or a monochrome document for performing image processing suitable for a color image after reading. If the color mode is not selected by default, a motor 65 for driving each transport roller so as to have a second transport speed corresponding to a monochrome original so as to have a reading speed corresponding to a monochrome original is provided. Control each part.

In the image discrimination, when it is judged that the original is a color original, the second original is controlled to be conveyed at a fourth conveying speed so as to perform reading corresponding to the color original.

In the image discrimination, when it is determined that the document is a monochrome document, the second reading unit is controlled to perform reading corresponding to the monochrome document. Alternatively, the data used for image discrimination by the first reading unit 11 may be stored and held in the memory as image data of the document, and the data after the monochrome document is read by the first reading unit may be stored. The control of the conveyance of the document may be the same as that of the monochrome mode.

When the mixed mode is selected by the mode selection section 67, the control section 64 conveys and reads each original at the sixth transport speed by the first reading section 11 for each original. The document size is determined from the image data read after the reading, the second reading unit 12 controls the reading corresponding to the document size based on the detected document size information, and performs the second reading at the time of reading. The motor 65 for driving each transport roller and each section are controlled so that the document is transported at the transport speed. When the mixed mode is not selected by the default setting, the motor 65 for driving each transport roller and each unit are controlled so as to transport a document corresponding to the same document size.

Further, in the image discrimination in the color mode, it is preferable to discriminate the size of the document together with the discrimination of the color document. In this case, the operability is improved because the user does not have to dare to select the mixed loading mode.

According to the above-described image reading apparatus, even when the original is a single-sided original or a double-sided original, a monochrome original or a color original, a mixed original size, and a mixed original of a monochrome original and a color original, reading with high productivity can be performed. It can be carried out.
Hereinafter, the operation of the image reading apparatus for each condition of the original will be described in detail with reference to FIGS. In FIGS. 4 to 7, illustration of the parts shown in FIG. 3 which are not used for the operation is omitted. The components of the second reading unit 12 including the first platen glass 14 are collectively indicated by △. Note that the second reading unit 12 can also be configured by the close contact type image sensor CIS similarly to the first reading unit 11.

Next, single-sided original reading and double-sided original reading in each of the monochrome mode and the color mode will be described. In the following description, the first to n-th originals are denoted by S1 to Sn, and the surface of the i-th original is Si-
1. The back surface is represented by Si-2. Then, in order to avoid complicated notation, for example, the i-th document Si is written using the notation Si-1 on the front surface and the notation Si-1 on the back surface, and S
Notation such as omitting the notation of i and attaching only the notation necessary for description to the drawings is adopted.

1. Operation in case of single-sided original in monochrome mode (FIG. 4) As shown in FIG.
When reading the original images of S1 and S2, if none of the modes is selected by the mode selection unit 67 of the operation display unit 66 in FIG. S1 is fed by the feed roller 19, passed through the first reading unit 11 without being read at the first transfer speed, and is conveyed by the conveying roller pairs 21 and 22, and the original S1 is, for example, A4, B5 or the like. If the document is small, the document is guided to the transport path 32 by the transport direction switching member 40 as shown in FIG.
In the case of a large size such as 4, the sheet is guided to the conveyance path 31 by the conveyance direction switching member 40, conveyed by the conveyance roller pair 26, and conveyed to the vicinity of the second reading unit 12. Second reading unit 12
When the leading end of the document S1 is detected by a sensor K2 provided near the document, the transport speed of the document S1 is switched to a second transport speed which is a transport speed for reading a monochrome document.
While being transported by the transport roller pairs 23 and 24, the sensor K2
The document S1 based on the information that the leading end of the document S1 is detected
The second reading unit 12 reads a document image on one side (one side) of the document S1 in synchronization with the leading end position of the document. The transport speed may be switched at a predetermined timing after the transport of the document is started without providing the sensor K2. In such a case, information on the elapsed time from the start of document conveyance and information on the number of steps of driving a stepping motor used as a drive source can be applied. The reading timing is a timing at which the image pickup device starts capturing image data after the exposure by the light source 51 is started.

The original S1 after the one-sided (one-sided) original image is read by the second reading unit 12 is switched from the second conveying speed to the third conveying speed, and the conveying roller pair 2 is switched.
4. The sheet is conveyed by being guided to the conveyance path 36 by the conveyance direction switching members 43 and 44, and is sequentially stacked so that one surface read by the discharge roller 25 and read on the discharge tray 30 is a lower surface.

The next original S2 is similarly sent out continuously during the transportation of the original S1, and the first original S2 is fed at the first transport speed.
Is transported to the vicinity of the reading unit. When the leading end of the document S2 is detected by a sensor K1 provided near the first reading unit 11, the transport speed of the document S2 is switched to a second transport speed which is a transport speed for reading a monochrome document, and a transport roller is provided. The original image of one side (one side) of the original S2 is read by the first reading unit 11 in timing with the leading end position of the original S2 based on information that the leading end of the original S2 is detected by the sensor K1 while being conveyed by the pair 21 and 22. Is read.

The original S2 after the one-sided (one-sided) original image is read by the first reading unit 11 is switched from the second conveying speed to the third conveying speed, and the second reading unit 12
In the same manner as in the case of the document S1, the paper is discharged so that one surface read on the paper discharge tray 30 becomes the lower surface, and is sequentially stacked on the document S1.

In reading the plurality of originals S1 and S2 described above, the conveyance of the originals S1 and S2 is controlled so that the readings are performed almost simultaneously. That is, the conveyance is controlled such that the original S2, which is the next original, reaches the vicinity of the first reading unit 11 at the same time when the original S1, which is the first original, reaches the vicinity of the second reading unit 12 at the same time. You. In order to perform such conveyance, after the conveyance of the previous document S1 is started, the conveyance of the previous document S1 is started at a predetermined document interval, and the next document S1 is started after a predetermined time has elapsed. What is necessary is just to control conveyance so that conveyance of S2 may be started.

The next original S3 following the original S2 is
During the conveyance of the document S2, the document S2 is sent out after a lapse of a predetermined time from the start of the conveyance of the previous document S2 so as to be at a predetermined document interval, and is controlled to be conveyed similarly to the document S1.

Further, the original S4 following the original S3 is controlled so as to be conveyed in the same manner as the original S2. Thereafter, conveyance of the originals S5, S6,... Is controlled in the same manner as the original S3 or the original S4.

When the originals S1 and S2 are large in size such as A3 and B4, the originals S1 and S2 pass through the transport path 31 as shown in FIG. Scan the original image. It is preferable that the document table 20 be provided with a mechanism for detecting the document size of the placed document when the document is placed. Based on the document size information of the detected document, FIG. Control is performed so as to switch the switching member 40 as shown in FIG.

In either of the cases shown in FIGS. 4A and 4B, one side (one side) of the originals S1 and S2 is read from the second reading section 1A.
The image data of two pages read by the second and first reading units 11 are sent to the second image processing unit 58 or the first image processing unit 57 in FIG. After the image processing such as is performed, it is stored in the memory 59.

In FIG. 4, when there are many originals to be read, as shown in Table 1, the second reading unit 12
,... Are sequentially read, and the first reading unit 11 sequentially reads even pages 2, 4, 6,... And the first image processing unit 57 or the second image processing unit 57. The image data is sent to the image processing unit 58, and after the image processing of pages 1 and 2 has been performed almost at the same time, it is stored in the memory 59, and the subsequent 3, 4
Similarly, the pages are also subjected to image processing for pages 3 and 4 substantially at the same time, and then stored in the memory 59. For example, a plurality of document images are read two pages at a time substantially simultaneously, and image processing is performed. Is stored in the memory 59.

[0063]

[Table 1]

As described above, a plurality of originals are sequentially conveyed, and a plurality of reading sections, for example, two reading sections 11 and 12 read a plurality of original images almost at the same time, and a plurality of image processing sections. For example, since a plurality of image processes are performed almost simultaneously by the first image processing unit 57 and the second image processing unit 58, a plurality of single-sided originals can be efficiently read.
This improves the productivity of image formation (copying). Further, by setting the transport speed of the document other than at the time of reading to be higher than at the time of reading, a plurality of single-sided documents can be read more efficiently, and the productivity is further improved.

2. Operation in case of double-sided printing in monochrome mode (FIG. 5) As shown in FIG. 5A, both sides of a plurality of monochrome (black-and-white) originals S1 and S2, that is, the front side of original S1 (S1-1) And the back side (S1-2), and the front side (S
In the case of reading the original image on 2-1) and the back side (S2-2), the duplex mode is selected by the mode selection section 67 of the operation display section 66 in FIG. When the double-sided mode is selected, the operation is performed in the double-sided mode. The first original S1 is fed from the original platen 20 by the feed roller 19 and reaches the vicinity of the first reading unit 11 at the first transport speed. Conveyed. When the leading edge of the document S1 is detected by a sensor K1 provided near the first reading unit 11, the transport speed of the document S1 is switched to a second transport speed that is a transport speed for reading a monochrome document, and the transport roller The original image of the front side S1-1 of the original S1 is read by the first reading unit 11 in timing with the leading end position of the original S1 based on information in which the leading end of the original S1 is detected by the sensor K1 while being conveyed by the pair 21 and 22. Is read.

After the original image on the front surface S1-1 is read by the first reading unit 11, the original S1 is switched from the second transport speed to the first transport speed and transported to the transport path 33. . The rear end of the document S1 conveyed to the conveyance path 33 is the first
When the sensor K3 reaches the vicinity of the reverse conveyance roller 27, the sensor K3
, The rotation direction of the first reverse transport roller 27 is switched in a state of being sandwiched by the first reverse transport roller 27 based on the detection information of the rear end, and the first reverse transport roller 27 is transported reversely to be read by the second reading unit. 12 is conveyed. When the document S1 is conveyed to the vicinity of the second reading unit 12 and the leading end of the document S1 is detected by a sensor K2 provided near the second reading unit 12, the conveyance speed of the document S1 is changed to the conveyance for monochrome document reading. Switch to the second transport speed, which is the
The document S1 is conveyed by the sensor K2 while being conveyed by the sensors 3 and 24.
The second reading unit 12 reads the document image of the back surface S1-2 of the document S1 at the timing corresponding to the position of the leading edge of the document S based on the information that the leading edge of the document S has been detected. Document S1 after document image on back side S1-2 is read by second reading unit 12
Is switched from the second transport speed to the third transport speed, guided by the transport roller pair 24 and the transport direction switching members 43 and 44 to the transport path 37 and transported, and the rear end of the document S1 is moved to the second transport speed. When reaching the vicinity of the reverse transport roller 28, the rear end is detected by the sensor K4, and the rotation direction of the second reverse transport roller 28 is switched in a state of being sandwiched by the second reverse transport roller 28 based on the detection information of the rear end. The sheet is reversely conveyed, and is conveyed by the conveyance direction switching member 44 to the upper discharge roller 2.
5, the paper is discharged by the paper discharge rollers, and is sequentially stacked on the paper discharge tray 30 such that the front surface S1-1 faces the lower surface.

The next document S2 is similarly sent out continuously during the transport of the document S1, and is transported at a first transport speed to the vicinity of the first reading unit. When the leading end of the document S2 is detected by a sensor K1 provided near the first reading unit 11, the transport speed of the document S2 is switched to a second transport speed which is a transport speed for reading a monochrome document, and a transport roller is provided. The original image of the front surface S2-1 of the original S2 is read by the first reading unit 11 in timing with the leading end position of the original S2 based on information obtained by detecting the leading end of the original S2 by the sensor K1 while being transported by the pair 21 and 22. Is read.

The original S2 after the original image on the front surface S2-1 is read by the first reading unit 11 is subsequently conveyed in the same manner as the original S1, and the back surface S2-2 in the second reading unit. Is read, and the paper is discharged onto the paper discharge tray 30.

In the reading of the back surfaces S1-2 of the plurality of documents S1 by the second reading unit and the reading of the front surface S2-1 of the documents S2 by the first reading unit, the reading is performed almost simultaneously. The conveyance of the originals S1 and S2 is controlled as described above. That is, the original S1, which is the previous original, is
At the same time when the document arrives in the vicinity of the second document 2, the conveyance is controlled so that the document S2, which is a later document, reaches the vicinity of the first reading unit 11.

Further, the original S3 following the original S2 is conveyed in the same manner as the original S2 and both sides are read (FIG. 5).
(B)).

As described above, for example, each of the two pages read by the second reading unit 12 and the first reading unit 11 from the back surface S1-2 of the document S1 and the front surface S2-1 of the document S2, respectively.
The image data for the page is sent to the second image processing unit 58 or the first image processing unit 57 in FIG. 9 and is subjected to image processing such as compression processing and data conversion at the same time.
9 is stored.

In FIG. 5, when there are a large number of originals for reading, as shown in Table 2, the first reading unit 11
Each page on the front side of each document is read in order as 3, 5,..., And each page on the back side of each document is read in order as 2, 4, 6,. Are sent to the first image processing unit 57 or the second image processing unit 58, and after the respective image processing of the back page of the previous document and the front page of the subsequent document are performed at about the same time, the memory 59.

[0073]

[Table 2]

In this case, as shown in Table 2, in reading the front side S1-1 of the first original S1 and the back side of the last original, the first reading section 11 or the second reading section 11 respectively.
, And the reading is not performed at the same time.

As described above, a plurality of originals are sequentially conveyed, and a plurality of reading units, for example, the two reading units 11 and 12 simultaneously copy respective original images on both sides of the plurality of originals at substantially the same time. Reading, since a plurality of image processing units, for example, the first image processing unit 57 and the second image processing unit 58 perform a plurality of image processings at substantially the same time, efficiently read a plurality of double-sided originals This improves the productivity of image formation (copying). Further, by setting the transport speed of the document other than at the time of reading to be higher than at the time of reading, a plurality of single-sided documents can be read more efficiently, and the productivity is further improved.

3. As shown in FIG. 6, when reading original images of a plurality of color originals S1 and S2, the color mode is set by the mode selection unit 67 of the operation display unit 66 in FIG. When selected, the printer operates in the color mode.
1 is fed by the feed roller 19 and is conveyed to the vicinity of the first reading unit 11. When the sensor K1 provided in the vicinity of the first reading unit 11 detects the leading edge of the document S1, the transport speed of the document S1 is switched to a fifth transport speed which is a transport speed for reading image identification, and the transport is performed. Roller pair 21,
The first reading unit 11 discriminates an image of a document image on one side (one side) of the document S1 by adjusting the timing to the position of the front end of the document S1 based on information that the front end of the document S1 is detected by the sensor K1 while being transported by the sensor 22 Read for.

Document S1 read by first reading section 11
Is sent to the first image processing unit 47, and the image determination processing is performed by the determination unit 61. As the image discrimination, a discrimination between a color document and a monochrome document is performed, and based on the discrimination result, the control unit 64 controls the driving of the motor 65 to change the rotation speed of the pair of conveying rollers 23, 24, The transport speed for reading by the second reading unit 12 is controlled to a low fourth transport speed for a color original, and to a medium second transport speed for a monochrome original. .

The original S1 after the one-sided (one-sided) original image has been read by the first reading unit 11 for image discrimination,
Switching from the fifth transport speed to the third transport speed,
The sheet is conveyed to the vicinity of the second reading unit 12 and the second reading unit 1
When the leading end of the document S1 is detected by the sensor K2 provided in the vicinity of the document 2, the transport speed of the document S1 is changed to the fourth speed which is the transport speed for reading the color document when the document S1 is a color document. Switch to transport speed or original S
When 1 is a monochrome original, the sensor K is switched to a second transport speed which is a transport speed for reading a monochrome original, and is transported by the transport roller pairs 23 and 24.
2, the second reading unit 1 adjusts the timing to the position of the leading edge of the document S1 based on the information that the leading edge of the document S1 has been detected.
At 2, a color or monochrome document image of the document S1 is read.

The document S1 after the document image is read by the second reading unit 12 is switched from the fourth transport speed or the second transport speed to the third transport speed, and the transport roller pair 24, The documents are transported by being guided to the transport path 36 by the transport direction switching members 43 and 44, and are sequentially stacked such that the image reading surface of the document S1 faces the lower surface.

The next document S2 is similarly sent out continuously during the transport of the document S1, and is transported at a first transport speed to the vicinity of the first reading unit. When the leading end of the document S2 is detected by a sensor K1 provided near the first reading unit 11, the transport speed of the document S2 is switched to a fifth transport speed which is a transport speed for reading image determination, and the transport is performed. The first reading unit 11 adjusts the timing of the leading edge of the document S1 based on the information obtained by detecting the leading edge of the document S1 by the sensor K1 while being conveyed by the pair of rollers 21 and 22. Read the original image.

The original S2 after the original image of the original S2 has been read by the first reading unit 11 is transported in the same manner as the original S1, and the original image is read by the second reading unit. The paper is discharged onto the paper discharge tray 30.

The reading by the second reading unit for reading the original images of the plurality of originals S1 and the reading by the first reading unit for discriminating the image of the original S2 are almost simultaneously performed. The document S1 to be executed,
The conveyance of S2 is controlled. That is, the original S which is the previous original
At the same time when 1 reaches the vicinity of the second reading unit 12,
The conveyance is controlled so that the later original S2 reaches the vicinity of the first reading unit 11.

Further, the original S3 following the original S2 is conveyed in the same manner as the original S2, and the image is determined, and the original image is read according to the image determination result.

As described above, for example, the second
The reading of the original image by the reading unit 12 and the first
The read image data and the image data for image determination read by the reading unit 11 for image determination are sent to the second image processing unit 58 or the first image processing unit 57 in FIG. Then, at the same time, image processing such as compression processing, data conversion, or image discrimination processing is performed, and stored in the memory 59, and the control of the document is controlled by the control unit based on the discrimination result.

In FIG. 6, when there are many originals to be read, as shown in Table 3, the first reading unit 11
After sequentially reading each page of each document as in 2, 3,..., And performing image discrimination, the second reading unit 12 performs each image reading in 1, 2, 3,. Each page of the document is sequentially read and sent to the first image processing unit 57 or the second image processing unit 58, and the image processing of the previous document and the image discrimination process of the subsequent document are performed at substantially the same time. Is made.

[0086]

[Table 3]

In this case, as shown in Table 3, the first reading unit 11 or the second reading unit respectively reads the first original S1 for image discrimination and the last original image. A single reading at 12 is performed and no reading is performed at the same time.

As described above, a plurality of color documents are sequentially conveyed, and a plurality of reading units, for example, two reading units 11 and 12 are read.
At about the same time, each document image of a plurality of documents is read at the same time, and a plurality of image processing units, for example, a discriminating unit 61 attached to the first image processing unit 57 performs image discrimination.
The image processing unit 58 performs image processing on the image data read substantially at the same time, so that a plurality of color documents can be read efficiently, and the productivity of image formation (copying) is improved. . Further, by setting the transport speed of the document other than at the time of reading to be higher than at the time of reading, a plurality of color documents can be read more efficiently, and the productivity is further improved.

Further, even if a monochrome document and a color document are mixed, a discrimination unit 61 determines whether the document is a monochrome document or a color document.
, It is possible to apply the reading conveyance speed suitable for each of the monochrome original and the color original, and the productivity of the image formation (copying) of the color original is further improved.

4. When the original is a color double-sided original (Fig. 7)
As shown in FIG. 7A, a plurality of color double-sided originals S
When reading the original image of S1 and S2, if the color mode and the duplex mode are selected by the mode selection section 67 of the operation display section 66 in FIG. 9, the apparatus operates in the color duplex mode. In this case, the front surface S1-
The conveyance of the original to the first second image reading unit 12 and the conveyance of the originals S1 and S2 until the reading of the front surface S2-1 of the next original S2 for image discrimination by the first reading unit 11 are: The document is controlled so as to be conveyed in the same manner as in the case of the color single-sided document described above.

The document S1 after the document image is read by the second reading unit 12 is switched from the fourth transport speed or the second transport speed to the third transport speed, and the transport roller pair 24, The sheet is guided to the conveyance path 35 by the conveyance direction switching member 43, and is conveyed to the subsequent conveyance path 34 (FIG. 7B).
When the trailing edge of the document S1 reaches the vicinity of the third reverse transport roller 29 provided in the transport path 33, the trailing edge is detected by the sensor K5, and the original is held by the third reverse transport roller 29 based on the detection information of the trailing edge. In this state, the rotation direction of the third reverse conveying roller 29 is switched, the sheet is reversed, guided upward by the conveying direction switching member 45, and circulated and conveyed to the first reading unit 11. The back surface S1-2 of the document S1 circulated and conveyed to the first reading unit 11 is processed in the same manner as the above-described front surface S1-1 until the subsequent reading by the second reading unit 12.

When reading the back side S1-2 of the original S1 for image discrimination by the first reading unit 11, the original image of the front side S2-1 of the next original S2 by the second reading unit 12 is read. Originals S1 and S2 so that reading is performed, respectively.
Is controlled to be conveyed.

Further, at the same time when the second reading section 12 of the back surface S1-2 of the document S1 reads the document image of the back surface S1-2, the first reading of the back surface S2-2 of the next document S2 is performed. Part 1
Documents S1 and S2 are conveyed or circulated, respectively, so that reading for image discrimination at 1 is performed.

The document S1 after the two-sided document image has been read by the second reading unit 12 is switched from the fourth transport speed or the second transport speed to the third transport speed, and is fed to the transport roller pair. 24, the document S1 is guided and conveyed to the conveyance path 31 by the conveyance direction switching members 43 and 44, and when the rear end of the document S1 reaches the vicinity of the second reverse conveyance roller 28, the rear end is detected by the sensor K4 and the rear end of the document S1 is detected. The rotation direction of the second reverse conveyance roller 28 is switched while being sandwiched by the second reverse conveyance roller 28 based on the detection information, and the second reverse conveyance roller 28 is reversed and conveyed to the upper discharge roller 25 by the conveyance direction switching member 44. The document S1 is guided, discharged by the discharge rollers, and sequentially stacked on the discharge tray 30 such that the front surface of the document S1 faces the lower surface (FIG. 7C).

The next original S2 and the succeeding original S3 are transported from the first reading section 11 to the second reading section 12 while the original S1 is being transported to the paper discharge tray, and the next original S3 is transported. From the document table 20 and transported at a first transport speed to a position near the first reading unit.

At the same time as reading of the back surface S2-2 of the document S2 by the second reading unit, reading of the front surface S3-1 of the document S3 is performed by the first reading unit 11 for image discrimination.

The original S2 after the original images on both sides of the original S2 have been read by the second reading section 12 is discharged onto the discharge tray 30 in the same manner as the original S1. First
The original S3 after the reading of the front surface S3-1 of the original S3 by the reading unit 11 for image discrimination is performed,
1, the front surface S3- at the second reading unit 12 thereafter.
1 original image reading, circulation conveyance, first reading unit 11
The reading of the back side S3-2 for image discrimination, the reading of the document image of the back side S3-2 by the second reading unit 12, and the discharge onto the discharge tray 30 are performed.

Further, the original S4 subsequent to the original S3 is conveyed in the same manner as the original S2, and the image of the front and back sides is identified, and the original image is read in accordance with the image identification result. Thereafter, both sides are similarly read as a set of a plurality of two-sheet originals in the same manner as the originals S1 and S2.

As described above, for example, the reading of the original image by the second reading unit 12 of the front surface S1-1 of the original S1 and the discrimination of the image by the first reading unit 11 of the front surface S2-1 of the original S2. Each of the read image data and the image data for image discrimination read in FIG.
Image processing unit 58 or the first image processing unit 57, respectively, is sent to the image processing unit such as compression processing and data conversion at the same time,
Alternatively, an image discriminating process is performed and stored in the memory 59, and the document is conveyed by the control unit based on the discrimination result.

In FIG. 7, when there are many originals to be read, as shown in Table 4, the first reading unit 11
After sequentially reading each page of each double-sided document as in 3, 2, 4,... And performing image discrimination, the second
, And sequentially reads each page of each double-sided document as in 1, 3, 2, 4,..., And is sent to the first image processing unit 57 or the second image processing unit 58, At the same time, the image processing of the first document and the image discrimination process of the second document are performed at the same time.

[0101]

[Table 4]

In this case, as shown in Table 4, when reading the front surface S1-1 of the first document S1 for image discrimination and reading the document image on the back surface of the last document, the first reading unit is used. 11 or the second reading unit 12 performs independent reading, and does not perform reading at the same time.

As described above, a plurality of color double-sided originals are sequentially conveyed, and a plurality of reading units, for example, two reading units 1 are read.
At about the same time in 1 and 12, each original image of a plurality of double-sided originals is read at the same time, and a plurality of image processing units, for example,
The image discriminating section 61 attached to the image processing section 57 performs image discrimination, and the second image processing section 58 performs image processing on the image data read almost at the same time. A two-sided original can be read efficiently, which improves the productivity of image formation (copying). Further, by setting the transport speed of the document other than at the time of reading to be higher than that at the time of reading, it is possible to read a plurality of color double-sided documents more efficiently, thereby further improving productivity.

Further, even if a monochrome document and a color document are mixed, a discrimination unit 61 determines whether the document is a monochrome document or a color document.
, It is possible to apply the reading conveyance speed suitable for each of the monochrome original and the color original, and the productivity of the image formation (copying) of the color original is further improved.

As described above, according to the image reading apparatus shown in FIGS. 3, 8, and 9, when the monochrome mode (or the color mode) is set, the original image is displayed on either one side or both sides. As shown in FIG. 5, the original image can be efficiently read by the two reading units 11 and 12, and the image processing can be performed simultaneously by the two image processing units 57 and 58, so that a more efficient reading operation can be performed. Is possible, and productivity can be improved. In the mixed mode of color and monochrome, whether the document image is single-sided or double-sided, as shown in FIGS. Can be performed, a more efficient reading operation can be performed, the productivity can be improved, and the discrimination processing by the discrimination scan is performed by the discrimination unit 61, and at the same time, the image processing of the image information by the main scan is performed. This can be performed by the image processing unit, and efficient image processing can be performed. As described above, by fully utilizing the two reading units in all modes, it is possible to provide an image reading apparatus (scanner) that can always achieve the highest productivity regardless of the type of document (monochrome / color and double-sided / single-sided). can do.

The image processing units 57, 5 of the image reading apparatus described above
An image processing signal is sent from 8 to a printer of, for example, an ink jet type or an electrophotographic type, and an image is formed by the printer based on the image processing signal. When the above-described image reading apparatus is incorporated in the image forming apparatus, an image processing signal is sent to the image writing unit 60 as shown in FIG. 9 and a laser beam modulated based on the image processing signal is supplied to the photosensitive drum. The image information is written by irradiating the photosensitive drum, and the image information written on the photosensitive drum is developed and transferred to a recording material to form an image.

FIG. 10 shows an example in which the first reading section 11 reads the first side of a document, and the second reading section 12 reads the second side of the document. In the embodiment shown in FIG. 10, a contact type image sensor (CIS) is used for the reading units 11 and 12.

The original S sent from the original table 20 by the feed roller 19 is transported by a pair of transport rollers 21, 22, 23 and 2
4 and the discharge tray 3 by the discharge rollers 25.
0, the first side of the original S is read between the pair of transport rollers 21 and 22, and the first side of the original S is read between the pair of transport rollers 23 and 24. The reading of the second surface is performed.

As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to these.
Various modifications are possible within the scope of the technical idea of the present invention. For example, the first reading unit 11 may be configured by an optical system and an image sensor, and the second reading unit 12 may be configured by a contact image sensor (CIS). Further, the reading speed for reading a color image may be set in a plurality of stages.

FIG. 11 is a block diagram showing the configuration of the drive system of the image sensor in the image reading apparatus according to the present embodiment.

In this embodiment, the image pickup device CCD1 of the first reading section 11 composed of a line CCD and the image pickup element CCD2 of the second reading section 12 (image pickup element 56 in FIG. 3) are synchronized with each other. It is characterized by being driven. In the present embodiment, both image pickup devices CCD1, C1
The CD 2 reads images almost simultaneously as described with reference to FIGS. Therefore, the imaging elements CCD1, C1,
For example, as shown in FIG. 1, the CD 2 may read an image with a slight phase shift when viewed in image units.

In such image reading, by driving the image pickup devices CCD1 and CCD2 in a synchronous relationship, the interference of the drive signals for driving the image pickup devices CCD1 and CCD2 is eliminated, and noise and harmful radio waves due to the interference are generated. Is effectively prevented.

In FIG. 11, CLG is clock generation means for generating a basic clock pulse, which is composed of a crystal oscillator. FDM divides the basic clock to obtain an image pickup device C.
A transfer clock pulse for driving CD1 and CCD2,
This is a driving pulse forming unit that generates various driving pulses such as a shift pulse, a reset pulse, and a clamp pulse.
DR1 and DR2 are imaging elements CCD based on the driving pulse
1. A driving circuit for driving the CCD 2.

The image data obtained by reading by the image reading apparatus shown in FIGS. 3 to 11 is sent to the image writing section 60 in FIG. 9 and used for image formation. Next, an image forming apparatus having the above-described image reading apparatus will be described with reference to FIG.

FIG. 12 is a diagram showing a configuration of an image forming apparatus for forming an image by an electrophotographic method. The image forming apparatus 70 shown in FIG. 12 includes the image reading device shown in FIG. 3 or 11 on the upper part thereof, and the image writing part 60 shown in FIG. Prepare for. The image forming apparatus 70 includes a photosensitive drum 71 that is exposed by a laser beam modulated based on image data in the image writing unit 60, a charger 72, a developing device 73, and a transfer device that are arranged around the photosensitive drum 71. A device 74, a separator 75, and a cleaning unit 76 are provided.

In the image forming apparatus 70 shown in FIG. 12, an image is formed on the recording material RM as follows. The laser beam from the image writing unit 60 is exposed to the rotating photosensitive drum 71 to form a latent image, and the latent image is developed by the developing unit 73 with toner. Paper cassette OA or OB at the bottom of FIG.
RM sent from above to the upper part of the figure by a pair of conveying rollers
Is transported between the photosensitive drum 71, the transfer device 74, and the separator 75 with good timing in synchronization with the rotation of the photosensitive drum 71 by the conveying roller pair 61, and the developed image is transferred to the recording material RM. Next, the recording material RM is transported by the transport belt 77 in the direction of the arrow in the figure, and the toner image is fixed by the fixing device 78 to form an image on the recording material RM.

When the recording material RM is completed with one-sided image formation, the recording material RM is discharged to the discharge portion 80 by the conveyance roller pair 85 by the operation of the conveyance direction switching member 81. Also, the recording material RM
When an image is also formed on the opposite surface of the recording medium RM, the conveyance direction switching member 81 is operated to feed the recording material RM to the lower reversing unit by the pair of reversing rollers 82 and the like, and then reversely convey the recording material RM to the rear conveyance unit 84 And is conveyed in a state of being inverted below the photosensitive drum 71, and is similarly discharged onto the discharge section 80 after an image is formed on the opposite surface.

[0118]

According to the first, fourth or sixth aspect of the present invention, noise and harmful radio waves due to interference between clock pulses generated when a plurality of image sensors are driven with partial temporal overlap are excellent. Therefore, the deterioration of image quality and the generation of harmful radio waves which occur when reading is speeded up are effectively prevented.

Using an image pickup device composed of a line sensor,
When reading an image of a traveling document, particularly when driving a plurality of image sensors in time, the problem caused by the interference of drive pulses for driving both image sensors is serious. According to the inventions of the fifth and fifth aspects, the problem of the interference between the driving pulses can be solved very effectively.

According to the third or seventh aspect of the present invention, with a simple configuration, interference between driving pulses in image reading using a plurality of image sensors can be prevented very well.

According to the eighth aspect of the present invention, an image reading apparatus for reading an image on a one-sided document at high speed and with high efficiency is realized.

According to the ninth aspect of the present invention, an image reading apparatus for reading an image on a double-sided document at high speed and with high efficiency is realized.

According to the tenth aspect of the present invention, an image reading apparatus for reading an image at high speed and high efficiency in reading either one-sided original or double-sided original is realized.

According to the eleventh aspect of the present invention, an image forming system for performing high speed and high efficiency from image reading to image formation is realized.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a vertical image area signal when an image is read using a plurality of image sensors.

FIG. 2 is a diagram illustrating a spectrum of a driving pulse in a case where there is no interference between driving pulses and a case in which there is a certain case.

FIG. 3 is a diagram illustrating a configuration of an image reading device according to an embodiment of the present invention.

FIG. 4 is a diagram for sequentially explaining an operation when a one-sided document is read in a monochrome mode by the image reading device of FIG. 3;

FIG. 5 is a diagram for sequentially explaining an operation when a two-sided original is read in a monochrome mode by the image reading device of FIG. 3;

FIG. 6 is a diagram for sequentially explaining an operation when a single-sided document is read in a mixed mode of color and monochrome by the image reading device of FIG. 3;

FIG. 7 is a diagram for sequentially explaining operations when reading a double-sided original in the mixed mode of color and monochrome by the image reading apparatus of FIG. 3;

8 is a diagram illustrating an example of a document conveyance direction switching member provided in the image reading apparatus of FIG. 3;

FIG. 9 is a block diagram of a control system of the image reading apparatus and the image forming apparatus according to the present embodiment.

FIG. 10 is a diagram showing another example of the image reading apparatus according to the present embodiment.

FIG. 11 is a block diagram of a driving system of an image sensor in the image reading apparatus according to the embodiment of the present invention.

FIG. 12 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 First reading unit 12 Second reading unit CLG Clock generation unit FDM drive pulse forming unit DR1, DR2 Drive circuit CCD1, CCD2 Image sensor

Claims (11)

[Claims] An original is scanned in a main scanning direction and a sub-scanning direction by using a plurality of image pickup elements for reading an image in pixel units,
An image reading method in which the plurality of imaging elements read different images, wherein the plurality of imaging elements are driven to read using driving pulses synchronized with each other. 2. The image reading method according to claim 1, wherein a contact image sensor is used as the image sensor. 3. The apparatus according to claim 1, wherein the driving pulse is a signal generated from a basic clock pulse generated by one clock generating unit and divided for the image sensor. The image reading method described in the above. 4. A document table, paper feeding means for feeding documents one by one from the document table, a transport path for transporting the document, each of which has an image sensor, and is provided at a plurality of positions on the transport path. An image reading apparatus, comprising: a plurality of reading units; and a driving unit that drives the plurality of imaging elements with synchronized driving pulses. 5. The image reading device according to claim 4, wherein the reading unit includes a contact image sensor. 6. The image reading apparatus according to claim 4, wherein at least one of the reading units includes a contact image sensor, and at least one of the reading units includes a reduction optical system and an image sensor. 7. The driving unit includes: one clock generating unit that generates a basic clock pulse; one driving pulse forming unit that generates a driving pulse from the basic clock pulse; and each of the imaging elements. The image reading device according to any one of claims 4 to 6, further comprising a driving circuit provided to drive the imaging element based on the driving pulse. 8. The apparatus according to claim 4, further comprising a first image sensor and a second image sensor, wherein the first and second image sensors read an image on the same surface of the document. The image reading device according to claim 1. 9. An image pickup apparatus comprising: a first image sensor and a second image sensor; an image on a first surface of a document read by the first image sensor; and a second image of the document read by the second image sensor.
The image reading apparatus according to claim 4, wherein the image reading apparatus reads an image on a surface. 10. A single-sided reading mode having a first image sensor and a second image sensor, wherein an image on the same side of a document is read by the first and second image sensors; and the first image sensor. 8. A double-sided reading mode in which an image on the first side of the original is read by the second imaging element and an image on the second side of the original is read by the second image sensor. Image reading device. 11. An image reading apparatus according to claim 4, further comprising: an image forming apparatus that forms an image on a recording material based on image information output by the image reading apparatus. Image forming system.