JP2003078722A - Image reader and image reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can surely prevent production of stripes caused by deposition of a foreign material on platen glass and suppress a local temperature rise in the platen glass. SOLUTION: The image reader 1 comprises an automatic document feeder 2 that carries a document 6 set on a document setting section 7 through a path passing on the platen glass 8 where an image is read, a moving means that moves an optical scanning system 14 including carriages 17, 18 used for reading scanning the image of the document along the platen glass 8 in the subscanning direction and a control means that executes a carrying document read mode where the image of the document 6 carried on the platen glass 8 by the automatic document feeder 2 at a velocity of Vd while moving the optical scanning system 14 by the moving means at a velocity Vs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for reading an image on a document, and more particularly to an image reading device equipped with an automatic document feeding device.

[0002]

2. Description of the Related Art Generally, in an image reading device such as a scanner device or a facsimile device, or an image reading device mounted in an image forming apparatus such as a copying machine, an automatic document for automatically feeding a document to be read. Some are equipped with a feeder. Further, as a reading method of an image reading apparatus using an automatic document feeder, a method called a platen scan method (or a flat bed scan method) and a method called a flow reading method (or a sheet feed scan method) are known. There is.

FIG. 5 is a schematic view showing an example of the arrangement of an image reading apparatus equipped with an automatic document feeder. The illustrated image reading device 51 is roughly configured to include a document pressing member 53 integrally including an automatic document feeding device 52, and a device main body 55 integrally including a reading optical unit 54. The automatic document feeder 52 has a configuration in which a delivery roll 56, a transport roll 57, a transport belt 58, and a discharge roll 59 are sequentially arranged along a document transport path. The document pressing member 53 is provided to be openable and closable with one end pivotally supported by the apparatus main body 55. The original document holding member 53 is provided with an original document setting section 61 for setting the original document 60 as an image reading target.

On the other hand, a platen glass (transparent glass) 62 serving as a document table is attached to the upper surface of the apparatus main body 55, and a reading optical section 54 is arranged below the platen glass 62. The reading optical unit 54 includes an optical scanning system 64,
The image pickup lens 65 and the CCD sensor 66 are provided. The optical scanning system 64 includes a full rate carriage 70 that holds a lamp 67, a reflector 68 and a first mirror 69, and a herb rate carriage 73 that holds a second mirror 71 and a third mirror 72. Further, the discharge tray 7 is provided on one side of the apparatus main body 55.
4 is attached.

When the image of the original is read by the platen scan method in the image reading apparatus 1 having the above-described structure, the original 60 set in the original setting section 61 is fed out by a feed roll 56 and a conveyance roll as shown by an arrow in FIG. 57
The original 60 is fed to the platen glass 62 by the conveying belt 58 and is stopped at a predetermined position on the platen glass 62 by the conveying belt 58.
In this state, the carriages 70 and 73 of the reading and scanning system 64 are moved from the left side to the right side in the figure at a predetermined speed ratio to move the document 60.
Image is read by the reading optical unit 54.

On the other hand, when the original image is read by the flow reading method, as shown in FIG. 6, the carriages 70 and 73 of the reading scanning system 64 are arranged below the platen glass 62.
Is stopped at the original reading position set in advance,
In this state, the original 60 set in the original setting section 61 is sent onto the platen glass 62 by the sending-out roll 56 and the carrying roll 57, and while the sent original 60 is carried on the platen glass 62 by the carrying belt 58, The image of the original 60 is read by the reading optical unit 54.

By the way, in the image reading apparatus adopting the platen scan system, the originals 60 to be read are fed one by one onto the platen glass 62, and each time, the originals 60 are read.
It is necessary to reciprocate the optical scanning system 64 (carriage 70, 73). On the other hand, in the image reading apparatus adopting the flow-reading method, a plurality of originals 60 are set in the original setting section 61, and the originals 60 are sequentially conveyed from the original setting section 61 while the originals are conveyed one by one. Since 60 images can be continuously read, higher productivity can be obtained as compared with the platen scan method.

[0008]

However, in the image reading apparatus adopting the flow-reading method, if foreign matter such as dust or dirt adheres to a part of the platen glass 62 on which the image of the original is read, the image is read. The foreign matter is continuously read together with the image of the original 60. for that reason,
The output image obtained by reading the original image has streaks that are not present in the original original image.

As a measure against this, for example, Japanese Patent Laid-Open No. 2000-1
In Japanese Patent No. 44901, the occurrence of streaks due to dust and dirt on the platen glass is detected, and the reading position of the original image by the optical scanning system (stop position of the optical scanning system) is changed based on the detection result. Alternatively, there is disclosed a technique of displaying a warning that dust or dirt is attached on the platen glass.

Further, in Japanese Patent Laid-Open No. 2000-152008, a CCD package having a plurality of lines of line sensors is provided, and each line sensor of the CCD reads an original image at a different position on the original feeding path, and the reading is performed. A technique for detecting streak-like noise based on the result and correcting (removing) it is disclosed.

However, Japanese Patent Laid-Open No. 2000-14490.
In the technique disclosed in Japanese Patent Publication No. 1, the response when detecting the occurrence of streaks depends on the cleaning work of the operator,
Further, even if the reading position by the optical scanning system is changed, dust or the like may be attached to the changed reading position, so that the generation of streaks cannot be completely prevented. Also,
In order to reduce the frequency of streaking, it is necessary to detect streaking without scanning the original before scanning the original image, and each time a streak is detected, a warning to that effect is displayed. Therefore, there is also a problem that productivity is remarkably reduced because it is necessary to promote cleaning of the platen glass or move the optical scanning system to change the reading position.

On the other hand, the technique disclosed in Japanese Unexamined Patent Publication No. 2000-152008 is effective in preventing the generation of streaks, but in order to realize this, it is necessary to use a special sensor, and the circuit configuration is also required. However, there is a drawback that a large increase in cost is unavoidable because it becomes complicated and large-scale.

Further, in the image reading apparatus adopting the flow-reading method, since the image of the original is read while the optical scanning system is stopped, the light from the light source (lamp) is continuously applied to one place of the platen glass. There is a risk that the platen glass is locally irradiated with high temperature due to irradiation. Also in the optical scanning system, thermal expansion occurs due to radiant heat generated from the light source, which may cause a positional relationship between optical components to be misaligned.

[0014]

SUMMARY OF THE INVENTION An image reading apparatus according to the present invention includes a document feeding unit for feeding a document along a path passing through a document table on which an image is read, and an optical scanning system for reading and scanning an image on the document. And a moving means for moving the document in the sub-scanning direction along the document table, and a conveyance document reading mode for reading an image of a document conveyed on the document table by the document conveying means while moving the optical scanning system by the moving means. And a control means.

In this image reading device, the control means executes the conveyed original reading mode to read the image of the original conveyed on the original table by the original conveying means while moving the optical scanning system by the moving means. For,
The reading position of the image by the optical scanning system changes continuously on the document table due to the movement of the optical scanning system. Therefore, even if foreign matter such as dust or dirt adheres to the document table, streaks will not occur in the read output image. Further, the movement of the optical scanning system prevents the light from the light source from continuously irradiating one portion of the document table, and the thermal expansion of each portion can be suppressed by the cooling action of the movement of the optical scanning system.

The image reading method according to the present invention reads an image of a document conveyed on a document table on which an image is read while moving an optical scanning system in the sub-scanning direction along the document table. Is.

In this image reading method, the reading position of the image by the optical scanning system is continuously changed on the original table by the movement of the optical scanning system. Therefore, even if foreign matter such as dust or dirt adheres to the document table, streaks will not occur in the read output image. Further, the movement of the optical scanning system prevents the light from the light source from continuously irradiating one portion of the document table, and the thermal expansion of each portion can be suppressed by the cooling action of the movement of the optical scanning system.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration example of an image reading apparatus to which the present invention is applied. The illustrated image reading device 1
In general, it is configured to include a document pressing member 3 integrally including an automatic document feeder 2 and a device main body 5 integrally including a reading optical unit 4. The document pressing member 3 is
It is openably and closably mounted on the apparatus body 5 with one end pivotally supported. On the upper part of the document pressing member 3, a document setting section 7 for setting a document 6 to be an image reading target.
Is provided. A platen glass (transparent flat glass plate) 8 serving as a document table is attached to the upper part of the apparatus main body 5.

The automatic document feeder 2 has a structure in which a delivery roll 9, a transport roll 10, a transport belt 11 and a discharge roll 12 are sequentially arranged along a document transport path. The delivery roll 9 serves to deliver the documents 6 set in the document setting section 7 one by one. Transport roll 10
Is for feeding the original document 6 delivered by the delivery roll 9 toward the platen glass 8. The conveyance belt 11 conveys the document 6 fed by the conveyance roll 10 on the platen glass 8. Discharge roll 1
Reference numeral 2 is for ejecting the original document 6 conveyed by the conveyor belt 11, and an ejection tray 13 is provided on one side of the apparatus main body 5 which is the ejection destination.

The delivery roll 9, the transport roll 10 and the discharge roll 12 are each composed of a pair of rolls. The conveyor belt 11 has a wide belt structure in the main scanning direction (depth direction in the drawing), and has a pair of support rolls 111 and 112 at both ends in the sub scanning direction (left and right direction in the drawing) orthogonal to the main scanning direction. Supported by. The conveyor belt 11 is provided between the pair of support rolls 111 and 112.
Is stretched in a loop. Pair of support rolls 11
Reference numerals 1 and 112 designate one side (for example, the support roll 111) as a driving side and the other side (for example, a support roll 112) as a driven side, and the driving side roll is rotated by the driving of a belt driving motor (not shown). Receive the conveyor belt 11
And the driven roll is configured to rotate.

On the other hand, the reading optical section 4 includes an optical scanning system 14,
The image pickup lens 15 and the CCD sensor 16 are provided. The optical scanning system 14 is a full-rate carriage 1.
7 and the herb rate carriage 18. A lamp 19, a reflector 20 and a first mirror 21 are mounted on the full rate carriage 17, and a second mirror 22 and a third mirror 23 are mounted on the half rate carriage 18.
Has been implemented.

The lamp 19 and the reflector 20 irradiate a line-shaped light along the main scanning direction toward the document surface, and the light reflected from the document surface is the first mirror 21, the second mirror 22, and the third mirror. The light is reflected in order by the mirror 23.
The image forming lens 15 forms an image of the light reflected by the third mirror 23 on the light receiving surface of the CCD sensor 16 at a predetermined magnification. The CCD sensor 16 serves as a reading sensor when reading an image of a document, and generates an image signal according to reflected light from the document. As the CCD sensor 16, for example, a 1-line CCD sensor is used for reading a monochrome image, and a 3-line color CCD sensor is used for reading a full-color image.

Each of the carriages 17 and 18 is movably supported in the sub-scanning direction by a guide mechanism (guide rail, etc.) (not shown), and is subordinated by a power transmission mechanism (eg, wire, pulley, etc.) not shown. It is provided so as to be movable in the scanning direction. Further, each of the carriages 17 and 18 is configured to be movable in the sub-scanning direction along the platen glass 8 by using a common carriage driving motor as a drive source. When moving in the sub-scanning direction, the half rate carriage 18 moves with a movement amount (moving speed) that is half that of the full rate carriage 17,
This allows the carriage 1 to be positioned at any position in the sub-scanning direction.
Even when 7 and 18 are moved, the optical path length from the document surface on the platen glass 8 to the light receiving surface of the CCD sensor 16 is always kept constant.

FIG. 2 is a block diagram showing the control arrangement of the image reading apparatus according to the embodiment of the present invention. In FIG.
The controller 30 controls the operation of the entire image reading apparatus according to a control program installed in advance. The reading modes that can be executed by the control of the controller 30 include a mode for reading an image of a document 6 placed on the platen glass 8 in a stopped state (hereinafter, a stop document reading mode) and a document 6 conveyed on the platen glass 8. However, there is a mode in which the image of the original 6 is read (hereinafter referred to as a conveyed original reading mode).

The controller 30 includes a document presence sensor 3
1 and the output signal from the document size detection sensor 32 are input. The document presence / absence sensor 31 detects the presence / absence of the document 6 in the document setting section 7. The document presence / absence sensor 31 is used to confirm whether or not the document 6 is set in the document setting section 7 in order to determine whether or not to execute the conveyed document reading mode, and to determine the final document during conveyance. To be The document size detection sensor 32 detects the document size on the document setting unit 7 and on the document conveyance path from the document setting unit 7 to the platen glass 8.

The controller 30 is connected to a roll drive motor 33, a belt drive motor 34, a carriage drive motor 35, and a speed change drive mechanism 36, which are the targets of operation control. The roll drive motor 33 is
Rolls (9,
It serves as a drive source for rotating (10, 12). The belt drive motor 34 serves as a drive source for rotating the conveyor belt 11. The carriage drive motor 35 serves as a drive source for moving the carriages 17 and 18 in the sub scanning direction. Each of the motors 33, 34, 35 is composed of, for example, a pulse motor.

The speed change drive mechanism 36 changes the moving speed of the carriages 17 and 18 by the carriage drive motor 35, and is constituted by using, for example, an electromagnetically driven clutch, gear or the like. When the difference between the moving speed of the optical scanning system 14 corresponding to the stopped original reading mode and the moving speed of the optical scanning system 14 corresponding to the conveyed original reading mode is large, the speed change drive mechanism 36 mechanically detects the difference. It is used to reduce the size. However, controller 3
Motor drive signal given to the carriage drive motor 35 from 0 (frequency of drive pulse in case of pulse motor)
If the difference between the moving speeds of the optical scanning system 14 in the stopped original reading mode and the conveyed original reading mode can be appropriately dealt with only by switching the above, it is not necessary to use the shift drive mechanism 36.

On the other hand, the memory 37 stores (holds) various control data, and as one of the control data, the rotation of the transport roll (9, 10, 12) at the time of reading the original image. Speed data and conveyor belt 11
The rotation speed data, the moving speed data of the carriages 17 and 18, and the like are stored. The control data stored in the memory 37 is stored in the controller 30 as needed.
Read out. The operation panel 38 is equivalent to a so-called user interface, and receives various input operations and selection operations by the operator and displays various information to the operator. The operation panel 38 includes, for example, an operation unit including buttons and switches and a display unit including a liquid crystal panel.

Next, the operation of the image reading apparatus 1 based on the control processing of the controller 30 will be described. First, when the image reading apparatus 1 is actually operated, the controller 3
At 0, either the stopped original reading mode or the conveyed original reading mode is executed. The reading mode (stop original reading mode and conveyed original reading mode) in the controller 30 is switched depending on whether the original 6 is set in the original setting section 7 or on the platen glass 8. Further, when the reading mode is switched between the stopped original reading mode and the conveyed original reading mode, a drive signal is given from the controller 30 to the variable speed drive mechanism 36 as required, and the carriage drive motor 35 is driven accordingly. The shift speed of the moving speed of the optical scanning system 14 is controlled according to the reading mode. Hereinafter, the operation of the apparatus when the stopped original reading mode is executed and when the conveyed original reading mode is executed will be described in order.

First, when the stopped original reading mode is executed, the opening / closing operation of the original pressing member 3 is performed manually by the operator, and the original 6 is set (placed) on the platen glass 8 during the opening / closing operation. . When the start button provided on the operation panel 38 is pressed in this state, a start instruction signal is sent from the operation panel 38 to the controller 30. In response to this start signal, the controller 30 gives a motor drive signal to the carriage drive motor 35. As a result, the carriages 17 and 18 of the optical scanning system 14 start moving from the home position in the sub scanning direction. As a result, the image of the document 6 set on the platen glass 8 is read and scanned by the movement of the carriages 17 and 18.

In the stopped original reading mode, when the reading speed when the image of the original 6 is read at a reading magnification (scaling rate) of 100% is defined as a reference reading speed "Vi", the moving speed of the full rate carriage 17 in the optical scanning system 14 is set. “Vs” is set to Vs = Vi, and the drive state of the carriage drive motor 35 is controlled by the controller 30 according to this setting condition.

On the other hand, when executing the transported original reading mode, the original 6 is set in the original setting section 7 by the manual operation of the operator. When the start button provided on the operation panel 38 is pressed in this state, a start instruction signal is sent from the operation panel 38 to the controller 30 in the same manner as above. The controller 30 receives this start instruction signal
Supplies a motor drive signal to the roll drive motor 33, the belt drive motor 34, and the carriage drive motor 35, respectively. As a result, the original document 6 set in the original document setting section 7 is sent out as shown by an arrow in FIG.
Then, it is sent onto the platen glass 8 by the carrying roll 10.

At this time, each of the carriages 17 and 18 of the optical scanning system 14 is at the home position (the left end in FIG. 3) according to the feeding timing of the document 6 by the transport roll 10.
The movement is started from, and when the carriage moving speed becomes a constant speed, the scanning for reading the first original image is started. At the first document reading start position, the document image reading position by the optical scanning system 14 and the automatic document feeder 2
Thus, the leading end position of the document 6 conveyed by is almost in agreement.

Here, the moving speed of the full rate carriage 17 during the reading of the document image is set to "V" as described above.
If s ″, this speed Vs corresponds to the scanning movement speed of the optical scanning system 14. This scanning movement speed Vs
Is the carriage drive motor 35 from the controller 30.
Is controlled by a motor drive signal provided to.

On the other hand, the original 6 sent onto the platen glass 8 by the transport roll 10 is transferred to the transport roll 10.
By the rotation of the transport belt 11 and the discharge roll 12, the platen glass 8 is transported in one direction at a constant speed. At this time, when the document conveying speed in a state where a part or the whole of the document 6 is substantially in contact with the platen glass 8 in a plane, the speed Vd is the platen glass 8
This is equivalent to the document transport speed above. The document conveying speed Vd is controlled by a motor drive signal given from the controller 30 to the roll drive motor 33 and the belt drive motor 34.

During the reading of the original image in the conveyed original reading mode, the roll driving motor 33, the belt driving motor 35, and the carriage driving motor 36 are driven by the respective motor driving signals supplied from the controller 30. It will be in the state of doing. At this time, the document conveying speed Vd by driving the roll driving motor 33 and the belt driving motor 34 is set to be higher than the scanning moving speed Vs by driving the carriage driving motor 35. Further, the difference (Vd-V) between the document transport speed Vd and the scanning movement speed Vs.
As described above, s) is set so as to match the reference reading speed Vi when the original image is read at the reading magnification (scaling rate) of 100% in the stopped original reading mode. As a result, the image of the original is read at the reference reading speed Vi in both the stopped original reading mode and the conveyed original reading mode.

As described above, in the image reading apparatus 1 according to the present embodiment, when the original image is read by the automatic original feeding apparatus 2 (when the conveyed original reading mode is executed), the motor drive signal given from the controller 30 is used. Each of the motors 33, 34, 35 is driven to read the image of the original document 6 conveyed on the platen glass 8 by moving the optical scanning system 14 in the sub-scanning direction along the platen glass 8. The reading position of the original image by the system 14 is set to the platen glass 8 by the movement of the optical scanning system 14.
The above changes continuously in the sub-scanning direction. Therefore, even if foreign matter such as dust or dirt adheres to the platen glass 8, the foreign matter can be read only momentarily by the movement of the optical scanning system 14, so that streaks appear in the output image obtained by the reading. It will not occur. As a result, it is possible to reliably prevent the generation of streaks in the image reading apparatus 1 that employs the so-called flow-reading method, in which the image of the original 6 is read while the original 6 is being conveyed.

Further, during the reading of the original image during execution of the conveyed original reading mode, the light from the lamp 19 is not continuously applied to one portion of the platen glass 8 due to the movement of the optical scanning system 14. It is possible to avoid a local temperature rise of the platen glass 8. In addition, a cooling action (air cooling action) due to the movement of the optical scanning system 14
Since the thermal expansion of each part is also suppressed by the above, it is possible to prevent the positional relationship between the optical components from being misaligned.

Further, the image reading apparatus 1 according to the present embodiment.
In the above, various conditions described below can be adopted as the control conditions in the conveyed document reading mode executed by the controller 30.

That is, as the first control condition, when the image of a predetermined number of originals 6 is read in the conveyed original reading mode, a motor drive signal is given from the controller 30 to the carriage drive motor 35 during the reading, whereby the optical scanning is performed. The carriages 17 and 18 of the system 14 are moved in one direction (one of the sub-scanning directions) at a constant speed. As a result, it is possible to avoid generation of vibrations due to conversion of the moving directions of the carriages 17 and 18 and change of moving speed during reading of a predetermined number of original images, and thus it is possible to obtain high-quality read images. Become. Incidentally, the predetermined number of sheets described here may be one, but preferably a plurality of sheets, more preferably the maximum number N of originals that can be set in the original setting unit 7 at one time.

As the second control condition, the required moving distance of the optical scanning system 14 when reading the image of a predetermined number of originals 6 in the conveyance original reading mode is set to the original 6 placed on the platen glass 8 in a stopped state. Is set to be equal to or less than the maximum moving distance of the optical scanning system 14 when the image is read (when the stopped original reading mode is executed). This eliminates the need to return the carriages 17 and 19 to the home position (moving start position) from the start to the end of reading a predetermined number of original images when executing the conveyed original reading mode. for that reason,
The original image can be read efficiently. By the way, when the maximum moving distance of the optical scanning system 14 during the execution of the stopped original reading mode is defined in the case of the full rate carriage 17, the maximum moving distance is substantially equal to the length Lmax of the platen glass 8 in the sub-scanning direction. Next to
Approximately 1 if specified in the case of the half rate carriage 18.
The distance is / 2Lmax.

As an application example of the second control condition, if the predetermined number is set to the maximum set number N, the maximum set number N of originals is set in the original setting section 7, and the maximum set number N of originals is set. When the images are sequentially read, the moving distance Ls of the optical scanning system 14 from the start of reading the first original image to the end of reading the Nth original image is equal to or less than the above-described maximum moving distance Lmax. Can be suppressed to. Therefore, in reading the images of the maximum number N of originals set in the original setting unit 7, from the start of reading the first original image to the end of reading the Nth (final) original image. Between the carriage 17,
It is not necessary to return 19 to the home position (movement start position). As a result, even when the maximum number N of originals is set in the original setting unit 7, the original image can be efficiently read.

As a third control condition, the document conveying speed Vd and the scanning moving speed Vs are variably controlled according to the document size. More specifically, the controller 30 detects (determines) the document size based on the output signal input from the document size detection sensor 32, and outputs a motor drive signal corresponding to the detection result (determination result) to each motor 33. ，
34 and 35, the document conveyance speed Vd and the scanning movement speed Vs are variably controlled. However, the reference reading speed Vi (Vi = Vd-Vs) is constant regardless of the document size.

As a specific example, a first case in which an A3 size original having a length of 420 mm in the direction of conveyance is conveyed by the automatic document feeder 2 to read an image, and a case of the direction along the direction of conveyance A with manuscript length of 210 mm
Consider a second case in which a 4 size or A5 size document is conveyed by the automatic document feeder 2 and an image is read.
In this case, the document conveyance speed Vd and the scanning movement speed Vs are controlled by the controller 30 so that the second case is faster than the first case. As a result, when reading an image of a document having a short document length in the transport direction, the optical scanning system 1 can be operated in the sub-scanning direction without reducing the readable number of document images with respect to the moving distance of the optical scanning system 14.
4 can be moved at a higher speed. Therefore, the effect of preventing the generation of streaks due to the adhesion of foreign matter on the platen glass 8 can be further enhanced.

As a fourth control condition, either the scanning movement speed Vs or the document conveyance speed Vd is variably controlled according to the reading magnification. More specifically, the controller 30 recognizes the reading magnification designated by the operator using the operation panel 38, and supplies a motor drive signal corresponding to the reading magnification to each of the motors 33, 34, 35 to perform scanning. Either one of the moving speed Vs and the document conveying speed Vd is variably controlled.

Specifically, if the reading magnification is "m",
In the controller 30, the scanning movement speed Vs and the document conveyance speed V are set so that the relationship of (Vd−Vs) = Vi / m is satisfied.
One of d is variably controlled. That is, when the scanning movement speed Vs is varied, the scanning movement speed VS at the reading magnification m is controlled so that Vs = Vd−Vi / m.
Further, when the document conveying speed Vd is changed, the reading magnification m
The document transport speed Vd at this time is controlled to be Vd = Vi / m + Vs. As a result, the image of the original can be read at a speed suitable for the reading magnification when the conveyed original reading mode is executed.

As a fifth control condition, the reading start position and the reading end position of the optical scanning system 14 at the time of executing the conveyed document reading mode are determined by one of the pair of support rolls 111 and 112 supporting the conveyor belt 11. It is set within a range Lr from the roll center to the other roll center. As a result, the image can be read on the platen glass 8 at a position where the document is reliably pressed by the transport belt 11, so that the image can be prevented from being blurred (out of focus).

In the above-described embodiment, as an operation condition for reading a document image in the transport document reading mode, the transport direction of the document 6 on the platen glass 8 and the moving direction of the optical scanning system 14 are the same direction ( However, the present invention is not limited to this.

That is, as shown in FIG. 4, as the operation conditions for reading the original image in the conveyed original reading mode, the original 6 is conveyed on the platen glass 8 and the optical scanning system 14 is operated.
The moving direction of may be set in the opposite direction (reverse direction). In this case, the document conveyance speed Vd and the scanning movement speed V
Since the reading speed is obtained by adding s, the relationship with the reference reading speed Vi described above is set to Vi = Vd + Vs.
Further, when the document conveying speed Vd is changed according to the reading magnification m, Vd = Vi / m-Vs is controlled, and when the scanning moving speed Vs is changed, Vs = Vi / m-Vd. To control.

[0051]

As described above, according to the image reading apparatus of the present invention, the control means executes the conveyed original reading mode to move the image of the original conveyed on the original table by the original conveying means. Since the scanning is performed while moving the optical scanning system by means, it is possible to surely prevent the generation of streaks due to the adhesion of foreign matter on the platen, and to prevent the positional relationship between the optical components due to the local temperature rise and thermal expansion of the platen. You can avoid madness.

Further, according to the image reading method of the present invention, the image of the original document conveyed on the original plate on which the image is read is read while moving the optical scanning system in the sub-scanning direction along the original plate. Therefore, it is possible to reliably prevent the generation of streaks due to the adhesion of foreign matter on the platen, and to prevent the positional relationship between the optical components from being misaligned due to a local temperature increase or thermal expansion of the platen.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of an image reading apparatus to which the present invention is applied.

FIG. 2 is a block diagram showing a control configuration of the image reading apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram showing an operation example of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram showing another operation example of the image reading apparatus according to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing a configuration example of a conventional image reading apparatus.

FIG. 6 is a diagram showing an operation example of a conventional image reading apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image reading device, 2 ... Automatic document feeding device, 4 ... Reading optical part, 6 ... Document, 7 ... Document setting part, 8 ... Platen glass, 9 ... Sending roll, 10 ... Conveying roll, 11 ... Conveying belt, 12 ... Ejecting roll, 14 ... Optical scanning system, 15
... Imaging lens, 16 ... CCD sensor, 17 ... Full rate carriage, 18 ... Herb rate carriage, 30 ... Controller, 33 ... Roll drive motor, 34 ... Belt drive motor, 35 ... Carriage drive motor, 11
1,112 ... Support roll

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 1/04 G03G 21/00 372 105 H04N 1/12 Z 1/107 F term (reference) 2H027 DA23 DA32 DB03 DB04 DB08 DB09 DE01 DE07 DE09 EC01 EC06 EC18 EC19 ED04 ED12 EE01 EE03 EE04 EE06 EF09 FA01 FA03 FA06 FA16 FA18 FA20 FA22 FA35 FB07 FB12 FB14 FB19 ZA07 2H107 DA03 2H108 A03 CA01 CB01 5C072 NA08A03

Claims (8)

[Claims] 1. An original document conveying means for conveying an original document on a path passing through an original document table on which an image is read, and an optical scanning system for reading and scanning an image of the original document are moved in the sub-scanning direction along the original document table. And a control unit that executes a conveyance document reading mode in which an image of a document conveyed on the document table by the document conveyance unit is read while the optical scanning system is moved by the movement unit. Image reading device. 2. The control means moves the optical scanning system in one direction at a constant speed during the reading of a predetermined number of original images in the conveyed original reading mode. The image reading device according to item 1. 3. The original control means controls the speed at which the original is conveyed on the original table by the original conveying means and the moving speed of the optical scanning system by the moving means during execution of the conveyed original reading mode. The image reading apparatus according to claim 1, wherein the image reading apparatus is variably controlled according to a size. 4. The control means, when executing the conveyed original reading mode, whichever of a conveyance speed of an original conveyed on the original table by the original conveying means and a moving speed of the optical scanning system by the moving means. The image reading apparatus according to claim 1, wherein one of the two is variably controlled according to a reading magnification. 5. The document conveying means has a conveyance belt provided in a state of facing the document table, and a pair of support rolls supporting both ends of the conveyance belt. 2. The reading start position and the reading end position of the optical scanning system at the time of execution are set within a range from one roll center of the pair of support rolls to the other roll center. Image reading device. 6. The required moving distance of the optical scanning system when reading a predetermined number of original images in the conveyed original reading mode is the optical distance when reading an original image placed on the original table in a stopped state. 3. The image reading apparatus according to claim 2, wherein the scanning distance is set to be equal to or less than the maximum movement distance of the scanning system. 7. The image reading apparatus according to claim 2, wherein the predetermined number is the maximum number of originals that can be set in the original setting unit at one time. 8. An image reading method, comprising: reading an image of a document conveyed on a document table on which an image is read, while moving an optical scanning system in a sub-scanning direction along the document table.