JPH1029739A - Image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the rapid load fluctuation applied to a drive motor for driving each carrying roller, which is caused by the difference between the carrying speed of the carrying rollers in a first carrying passage and the carrying rollers in a second carrying passage. SOLUTION: A document D carried in a connection passage 30 is restricted by rollers 54 and 55 and rollers 56 and 57 at two positions and carried curved so that the radius of its curvature becomes an approximate mean value of the radius of the curvatures of those of an outer guide plate 28 and inner guide plate 29. In the case where the document D is kept not pressed against the inner guide plate 29 in a connection passage 30, a loop detecting section 70 is held in an OFF state, and held in an ON state in the case where the document D is pressed against the inner guide plate 29, outputting a critical loop detection signal to a control section. The control section varies the rotation speed of a first or second drive motor by inputting the critical loop detection signal so that the radius of the curvature of the document D is held within the range of the radius of the curvature restricted by the connection passage 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus which is applied to a facsimile apparatus or the like and reads an original image by scanning an image surface of an original conveyed in a conveying path.

[0002]

2. Description of the Related Art FIG. 4 is a schematic structural view of a facsimile apparatus to which a conventional image reading apparatus is applied. Reference numeral 1 denotes a reading section in which an image reading apparatus 2 is arranged. A document loading table for loading the document D, a document discharge tray 4 for discharging the document D whose image is read by the image reading device 2, and a recording paper 5 based on image information received via a telephone line. An image reading apparatus 2 for forming an image;
A recording unit 6 for transmitting the image information read by the recording unit 6 is a paper feed cassette detachably mounted on the recording unit 5 and containing recording paper.

FIG. 5 and FIG. 6 are a schematic diagram showing a conventional image reading apparatus and a perspective view showing a transport mechanism in the conventional image reading apparatus, respectively.
Pickup roller for pressing against the original D loaded in the
Reference numeral 13 denotes a feed roller and a separation roller disposed at the entrance of the first transport path 14, and reference numerals 15 and 16 denote a transport roller disposed in the first transport path 14 and a pressure roller pressed against the transport roller. Here, rollers 12, 13 and roller
Reference numerals 15 and 16 denote first transporting originals D in the first transport path 14.
Of transport means.

Reference numeral 17 denotes a scanner unit serving as image reading means arranged on the second transport path 18, 19 denotes a white reference plate facing the scanner unit 17, and 20 and 21 denote scanner units 17 on the second transport path 18.
The transport roller disposed upstream of the scanner and the pressure roller pressed against it, 22 and 23 are the transport roller disposed downstream of the scanner unit 17 in the second transport path 18 and the pressure roller pressed against it, 24 and Reference numeral 25 denotes a paper discharge roller disposed at the exit of the second transport path 18 and a pressure roller pressed against the paper discharge roller. Here, the rollers 19 to 24 constitute a second transport unit that transports the document D in the second transport path 18.

Reference numeral 26 denotes a document detection sensor for detecting the document D in front of the scanner section 17 in the second transport path 18, and reference numeral 27 denotes a stamp mechanism disposed in front of the paper discharge roller 24 in the second transport path 18. Further, 28 and 29 are an outer guide plate and an inner guide plate which constitute the connection path 30 having a substantially constant radius of curvature,
The connection path 30 connects the first conveyance path 14 and the second conveyance path 18 arranged so as to be parallel to each other in the vertical direction.

In the transport mechanism shown in FIG. 6, 31 is a drive motor for driving the first transport means and the second transport means, 32 is a drive pulley fixed to a drive shaft of the drive motor 31, and 33 is a drive pulley. A drive belt wound around a pulley 32 and driven pulleys 34 to 37, respectively.
The rollers 36, 37 are connected to the rollers 15, 20, 22, 24, respectively, and transmit the driving force from the driving motor 31. Reference numeral 38 denotes a gear connected to the conveyance roller 15 by a connection shaft 38a, and transmits the driving force from the conveyance roller 15 to the feed roller 12 and the separation roller 13 by gear trains 39 and 40, respectively. The rotational force of the feed roller 12 is transmitted to the pickup roller 11 by a gear train 41.

Next, a reading operation in the image reading apparatus shown in FIG. 5 will be described. When the drive motor 31 is driven by a drive signal from a control unit (not shown), the drive force of the drive motor 31 is transmitted to the driven pulleys 34 to 37 via the drive pulley 32 and the drive belt 33. At this time, as the pickup roller 11 rotates, one or more originals D are fed into the nip portion between the feed roller 12 and the separation roller 13 by the pickup roller 11. Here, the driving force from the gear 38 is transmitted to the separation roller 13 via a torque limiter (not shown), and when only one document D is fed to the nip portion by the pickup roller 11, When the document D is fed into the first conveyance path 14 together with the feed roller 12 by rotating following the feed roller 12, and when two or more documents D are fed to the nip by the pickup roller 11, By rotating in the opposite direction to the roller 12, the remaining document D excluding the uppermost portion is pushed back onto the document loading table 3.
And feeds only one document D together with the feed roller 12 into the first transport path 14.

The document D fed into the first transport path 14 is transported into the connection path 30 while being held between the transport roller 15 and the pressure roller 16. The document D conveyed into the connection path 30 is conveyed along the outer guide plate 28 until the leading end is clamped by the conveying roller 20 and the pressure roller 21, and is clamped by the rollers 20, 21, and then the rear end Until the roller comes out of the rollers 15 and 16, the rollers are constrained at two positions by the rollers 15 and 16 and the rollers 20 and 21 so that the radius of curvature becomes an intermediate radius of curvature between the outer guide plate 28 and the inner guide plate 29. The document D is transported while the rear end of the document D is
Continue until you exit 5 and 16. The document D transported into the second transport path 18 by the rollers 20 and 21 is inserted between the scanner unit 17 and the white reference plate 19 after the leading edge is detected by the document detection sensor 26.

A scanner unit 17 composed of an equal-magnification optical system, a CCD line image sensor, and the like scans the image surface of the original D conveyed at a predetermined reading speed at a reading cycle corresponding to the pixel density, thereby forming an image. Read the image formed on the surface. The document D whose image has been read is continuously transported in the second transport path 18 by the transport roller 22 and the pressure roller 23, and is discharged onto the document discharge tray 4 by the discharge roller 24 and the pressure roller 25. Is done. The stamp mechanism 27
In the case where printing of the completion mark is set in advance, the completion mark is printed on the document D by pressing a stamp member (not shown) on the document D whose image has been read by the scanner unit 17.

In the image reading apparatus as described above, the transport speed corresponding to the pixel density in the reproduced image is accurately controlled,
In addition, a stepping motor is usually used as the drive motor 31 because control for stopping / restarting the conveyance of the document D during reading may be required due to the limitation of the memory capacity for temporarily storing the line image signal. Typically,
Approximately 2,000-
If the driving speed is higher than 3000 pps (pulse per second), the torque is attenuated. Therefore, the upper limit of the driving speed is limited to about 3500 pps or less.

In recent years, in facsimile apparatuses and the like, it has been required to increase the reading speed of the image reading apparatus, and in order to realize such a demand, it is necessary to increase the document conveying speed. . However, since the drive speed of the drive motor 31 is limited to about 3500 pps or less, if the transport speed is to be increased beyond this limit,
It is necessary to reduce the reduction ratio of the transport mechanism or to increase the diameter of the transport roller 15 or the like. When the reduction ratio of the transport mechanism is reduced and the roller diameter of the transport roller 15 or the like is increased, the load on the drive motor 31 increases, so a large stepping motor must be used and the drive current must be increased. However, in this case, since the vibration level and the noise level from the drive motor 31 at the time of driving are increased, there is a problem that the quietness of the device is reduced.

In order to solve the above problems, recent image reading apparatuses have realized a reduction in vibration level and noise level by distributing a load by driving a transport mechanism by two drive motors. There is something.

[0013]

FIG. 7 is an explanatory view of a transport speed when a transport mechanism is driven by two drive motors in a conventional image reading apparatus. The members described with reference to FIGS. Corresponding members have the same reference characters allotted, and description thereof will not be repeated. In FIG. 7A, 41 and 42 are:
A transport roller that rotates by a driving force from a first drive motor (not shown) and a pressure roller that presses against the transport roller 43
And 44, a transport roller that rotates by a driving force from a second drive motor (not shown) and a pressure roller that presses against the transport roller. Here, assuming that the transport speed of the document D in the tangential direction by the transport roller 41 is V ₁ and the transport speed of the document D in the tangential direction by the transport roller 43 is V ₂ , the transport speed V ₁ is equal to the transport speed V _2. The rear end is sandwiched by rollers 41 and 42 and the front end is
The document D transported while being clamped between 3, 44 is connected to the connection path 3
The outer guide plate 28 and the inner guide plate 29 are conveyed while being curved within the radius of curvature defined by 0.
Are not pressed.

However, an error occurs in the set rotation speed due to an error in the drive pulse output to the first drive motor or the second drive motor, or wear of the transport roller 41 or the transport roller 43 causes the transport. When the speed V ₁ <the transport speed V ₂ , the radius of curvature of the document D sandwiched between the rollers 41 and 42 and the rollers 43 and 44 increases with the lapse of the transport time, and is regulated by the inner guide plate 29. After the predetermined radius of curvature is reached, the tension is increased by pressing against the inner guide plate 29. In this state, the rotational load of the transport roller 43 increases, and the trailing end of the document D comes out of the rollers 41 and 42, and the tension generated on the document D disappears instantaneously. Decrease. The sudden change in load on the transport roller 43 causes the second drive motor for driving the transport roller 43 to lose synchronism, and the transport speed of the document D by the transport roller 43 fluctuates. Therefore, at this time, if the image reading of the document D is being performed, the scanner unit 17 cannot scan the image surface at every predetermined pitch, so that a reading error occurs and the image quality of the reproduced image is reduced. Cause.

Further, as shown in FIG.
In an image reading apparatus provided with a platen roller 45 closely contacted with the document 7, the original D is conveyed while the rear end is held between the rollers 41 and 42 and the front end is held between the platen roller 45 and the scanner unit 17. , Transport speed V
_{Even when 1} <conveyance speed V ₂ , the same problem as in the case of the image reading apparatus shown in FIG. 7A occurs.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problem by causing a sudden change in load on a drive motor for driving a document conveying means due to a difference in conveying speed between the first conveying means and the second conveying means. An object of the present invention is to provide an image reading apparatus which does not generate any image.

[0017]

According to a first aspect of the present invention, there is provided an image reading apparatus comprising: a first driving motor; a first driving motor disposed on a first conveyance path; A first transport unit that transports the original by the transmitted torque, a second drive motor, and a second transport motor that is disposed on the second transport path and transports the original by the torque transmitted from the second drive motor. And a curved connection path that connects the first conveyance path to the second conveyance path, and guides the document sent out from the first conveyance path to the second conveyance path;
An image reading device that scans an image surface of a document conveyed in a second conveyance path by the second conveyance device and reads the image; Loop detection means for detecting a change in the radius of curvature of the document which is being conveyed and whose leading end is being conveyed by the second conveyance means in the connection path; and the radius of curvature of the document is determined by the loop detection means. The rotation of the first drive motor or the second drive motor is controlled such that the original is within the range of the radius of curvature defined by the connection path when it is detected that the limit value of the defined radius of curvature has been reached. Control means for changing the speed.

Further, the image reading apparatus according to claim 2 is
The control unit falls within the range of the radius of curvature defined by the connection path from the time when the loop detection unit detects that the radius of curvature of the document has reached the limit value of the radius of curvature defined by the connection path. Until that is detected, one of the first drive motor and the second drive motor is stopped.

Further, the image reading apparatus according to the third aspect of the present invention,
The control unit falls within the range of the radius of curvature defined by the connection path from the time when the loop detection unit detects that the radius of curvature of the document has reached the limit value of the radius of curvature defined by the connection path. The speed ratio between the rotation speed of the first drive motor and the rotation speed of the second drive motor is changed until the occurrence of the collision is detected.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a schematic configuration diagram showing an embodiment of an image reading apparatus according to the present invention, and a perspective view showing a transport mechanism in the image reading apparatus of the present embodiment, respectively, and will be described with reference to FIGS. The same reference numerals are given to members corresponding to the members described above, and description thereof is omitted. Reference numeral 51 denotes a pickup roller that presses the original D loaded on the original loading table 3; 52 and 53, a feed roller and a separation roller disposed at the entrance of the first transport path 14; These are a transport roller disposed on the transport path 14 and a pressure roller pressed against the transport roller.
Here, the rollers 52, 53 and the rollers 54, 55
14 constitutes a first transport unit for transporting the document D. Reference numerals 56 and 57 denote scanner units in the second transport path 18.
The transport roller disposed upstream of the roller 17 and the pressure roller 58 and 59 pressed against the roller are the transport roller disposed downstream of the scanner unit 17 in the second transport path 18 and the pressure roller 60 pressed against the roller. And 61, a paper discharge roller disposed at the exit of the second transport path 18 and a pressure roller pressed against the paper discharge roller. Here, the rollers 56 to 61 constitute a second transport unit that transports the document D in the second transport path 18. Also,
70 is a loop detection unit arranged on the inner guide plate 29.

In the transport mechanism shown in FIG. 2, 81 is a first drive motor for driving the first transport means, 82 is a drive pulley fixed to the drive shaft of a drive motor 91, and 83 is a driven pulley 82 The driven belt is wound around the pulley 84, and the driven pulley 84 is connected to the transport roller 54 to transmit the driving force from the first driving motor 81. 85 is the connecting shaft
The gears 85a are connected to the transport roller 54. The gear trains 86 and 87 transmit the driving force from the transport roller 54 to the feed roller 52 and the separation roller 53, respectively. The rotational force of the feed roller 52 is picked up by a gear train 88.
It is transmitted to 51. Reference numeral 91 denotes a second drive motor for driving the second transport means, 92 denotes a drive pulley fixed to the drive shaft of the second drive motor 91, and 93 denotes a drive pulley 92 and driven pulleys 94 to 96, respectively. The driven pulleys 94, 95, 96 are connected to the rollers 56, 58, 60, respectively, and transmit the driving force from the second drive motor 91.

Next, a reading operation in the image reading apparatus of the present embodiment will be described. When the drive motors 81 and 91 are driven by drive signals from a control unit described later, the drive force of the first drive motor 81 is reduced by the drive pulley 82 and the drive belt.
The rollers 56, 58, and 60 are rotated forward by the driving force of the second drive motor 91, which is transmitted to the driven pulley 84 via 83. At this time, the pickup roller 51 is rotated by the driving force from the driven pulley 82, so that one or more originals D are sent to the nip portion between the feed roller 52 and the separation roller 53 by the pickup roller 51. Here, the driving force from the gear 85 is transmitted to the separation roller 53 via a torque limiter (not shown), and when only one document D is fed to the nip portion by the pickup roller 51, When the feed roller 52 is driven to rotate and feeds the document D together with the feed roller 52 into the first transport path 14, and when two or more documents D are fed to the nip by the pickup roller 51, Feed roller 52
The document D excluding the uppermost portion is pushed back onto the document loading table 3 by rotating in the opposite direction to the original document D. Thereafter, the document D is rotated by the feed roller 52 and only the uppermost document D is transported together with the feed roller 52 in the first conveyance. Paper is fed into the path 14.

The document D fed into the first transport path 14 is transported into the connection path 30 while being held between the transport roller 55 and the pressure roller 56. The document D conveyed into the connection path 30 is conveyed along the outer guide plate 28 until the leading end is clamped by the conveying roller 56 and the pressure roller 57, and is clamped by the rollers 56, 57, and then the rear end. Until the roller comes out of the rollers 54, 55, it is constrained at two positions by the rollers 54, 55 and the rollers 56, 57, and is curved so that the radius of curvature becomes an intermediate radius of curvature between the outer guide plate 28 and the inner guide plate 29. This state is continued until the trailing edge of the document D comes out of the rollers 55 and 56. The document D transported into the second transport path 18 by the rollers 56 and 57 is inserted between the scanner unit 17 and the white reference plate 19 after the leading edge is detected by the document detection sensor 26.

The scanner unit 17 constituted by an equal-magnification optical system, a CCD line image sensor and the like scans the image surface of the document D conveyed at a predetermined reading speed at every reading cycle corresponding to the pixel density. Read the image formed on the surface. The document D from which the image has been read is continuously transported in the second transport path 18 by the transport roller 58 and the pressure roller 59, and is discharged onto the document discharge tray 4 by the discharge roller 60 and the pressure roller 61. Is done. The stamp mechanism 27
In the case where printing of the completion mark is set in advance, the completion mark is printed on the document D by pressing a stamp member (not shown) on the document D whose image has been read by the scanner unit 17.

In the image reading apparatus of this embodiment, the transport speed corresponding to the pixel density in the reproduced image is accurately controlled,
In addition, stepping motors are used as the driving motors 81 and 91 because control of stopping / restarting the conveyance of the document D during reading is required due to the limitation of the memory capacity for temporarily storing the line image signal. And the control unit is
Drive the drive motors 81 and 91 with a drive pulse of pps or less,
When the loop detector 70 is off, the reference drive pulses P _D1 , P ₂ set so that the transport speed of the document D by the rollers 52 to 55 and the transport speeds V ₁ , V _{2 of the} rollers 56 to 61 are equal. _D2 is output to the drive motors 81 and 91, respectively.

FIG. 3 is a cross-sectional view for explaining the configuration and operation of the loop detection unit in the image reading apparatus according to the present embodiment. FIG. 3A shows an off state of the loop detection unit 70 and FIG. )
Indicates the ON state of the loop detection unit 70, respectively. The loop detection unit 70 includes a holder 71 fixed to the outer surface of the inner guide plate 29 and a micro switch 72 housed in the holder 71.

Here, the microswitch 72 is connected to the connection path 30.
When the document D is not pressed against the inner guide plate 29, the detection lever 72a is biased to an off position protruding from the guide surface of the inner guide plate 29 by a predetermined amount. In contrast, when the conveying speed V ₂ of the conveying roller 56 is greater than the conveying conveying speed V ₁ of the conveying roller 54 is sandwiched by the tip end side is sandwiched roller 56 and 57 by rear end rollers 54 and 55 The radius of curvature of the document D increases with the passage of the transport time. When the radius of curvature of the original D becomes larger than the inner guide plate 29 by a predetermined amount or more, the original D comes into contact with the detection lever 72a, and thereafter, the original D comes into pressure contact with the detection lever 72a or the inner guide plate 29 and tension is applied. Increases, the detection lever 72a swings to the ON position by the tension of the document D and presses the push button 72b as shown in FIG. 3B. As a result, the microswitch 72 is turned on, and outputs a limit loop detection signal to the control unit 62.

FIGS. 8 and 9 are flowcharts showing the control of the control unit for the drive motor in the image reading apparatus of the present embodiment. When the document D is transported by the first control shown in FIG. 8, the control unit 62 first determines that the transport speeds of the documents D by the rollers 52 to 55 and the transport speeds V ₁ and V ₂ by the rollers 56 to 61 are equal to each other. The reference drive pulses P _D1 and P _D2 are set (step S1), and the drive motors 81 and 91 are driven by the reference drive pulses P _D1 and P _D2 (step S2). Thereafter, the control unit 62 monitors whether or not a limit loop detection signal is input from the microswitch 72 of the loop detection unit 70 (step S3), and discharges the document D without inputting the limit loop detection signal. When the paper is completed (Yes in step S4), the control is ended. If the limit loop detection signal is input before the discharge of the document D is completed (YES in step S3), only the driving of the second drive motor 91 is stopped and the reading of the document D is performed. The operation is temporarily suspended (step S5).
This state is continued until the limit loop detection signal from the micro switch 72 is turned off (No in step S6),
If the limit loop detection signal from the micro switch 72 is turned off (YES in step S6), the driving of the second drive motor 91 and reading of the document D are restarted (step S7), and the discharge of the document D is completed (step S7). The above control is continued until step S4).

The original D is controlled by the second control shown in FIG.
First, the control unit 62 sets the reference drive pulses P _D1 and P _{D2 at} which the transport speeds V ₁ and V _{2 of} the original D by the rollers 52 to 55 and the rollers 56 to 61 are equal to each other.
(Step S10) The drive motors 81 and 91 are driven by the reference drive pulses P _D1 and P _D2 , respectively (Step S1).
1). Thereafter, the control unit 62 monitors whether or not a limit loop detection signal is input from the microswitch 72 of the loop detection unit 70 (step S12), and discharges the document D without inputting the limit loop detection signal. When the paper is completed (step S1
If yes in 3), the control ends. If the limit loop detection signal is input before the discharge of the document D is completed (YES in step S12), the drive pulse output to the second drive motor 91 is set to the reference frequency _PD2. From P _D2
'(Step S14). Here, P _D2 ′ = P _D2 −
Has the relationship P _0, P ₀ is the number of pulses corresponding to the amount of decrease in the conveying speed V ₂ which is set in advance. As a result, the transport speed V ₂ is reduced by a predetermined reduction amount, and the speed ratio between the rotation speeds of the drive motors 81 and 91 changes. This state is continued until the limit loop detection signal from the micro switch 72 is turned off (No in step S15), and if the limit loop detection signal from the micro switch 72 is turned off.
(If yes in step S15), and returns the drive pulses to be output to the second drive motor 91 to the reference frequency P _D2 (step S1
6) The above control is continued until the discharge of the document D is completed (step S13).

In the image reading apparatus of this embodiment, the connection path 30
The micro switch 72 was actuated by the tension of the document D in the inside, and the increase in the radius of curvature of the document D was detected.
In order to detect a change in the radius of curvature of the document D, a photo interrupter that optically detects the document D, a gap sensor that magnetically detects the document, or the like can be used. In the above description, the loop detection unit 70 is provided on the inner guide plate 29.
Has been described only when the outer guide plate is
By arranging a loop detection unit having the same configuration as the loop detection unit 70 in the detection unit 28, it is possible to detect a change in the radius of curvature such that the document D contacts the outer guide plate 28. When the document D contacts the outer guide plate 28, the influence on the reading speed is small, but the first drive motor 81 is stopped by the limit loop detection signal from the loop detector of the outer guide plate 28, or the rotation speed is reduced. By executing the control for lowering, it is possible to prevent, for example, generation of wrinkles on the document D and rubbing of the document D against the outer guide plate 28 to make the image thinner.

As described above, according to the image reading apparatus of the present embodiment, the connection of the document D conveyed in a state where the rear end side is sandwiched by the rollers 54 and 55 and the front end side is sandwiched by the rollers 56 and 57. A loop detector 70 that detects an increase in the radius of curvature in the path 30, and the radius of curvature of the document D reaches the limit value of the radius of curvature defined by the connection path 30 by the limit loop detection signal from the loop detector 70. A control unit 62 that changes the rotation speed of the first drive motor 81 or the second drive motor 91 so that the document D falls within the range of the radius of curvature defined by the connection path 30 when the change is detected. Accordingly, an error occurs in the set rotation speed due to an error in the drive pulse output to the first drive motor 81 or the second drive motor 91, or the transport roller 54 or the transport roller 56
The transport speed V _{1 is} less than the transport speed V _{2 due to} wear of the original D, and even when the original D is pressed against the inner guide plate 29, the original D can be kept within the range of the radius of curvature defined by the connection path 30. It is possible to prevent the load of the drive motors 81 and 91 from suddenly fluctuating at the time of reading the data D to prevent the step-out or the like from occurring. As a result, the scanner unit 17 can reliably scan the image plane at every predetermined pitch with respect to the document D, and a reading error occurs due to a change in the transport speed with respect to the document D, and the reproduced image is reproduced. Can be prevented from deteriorating.

Further, the control section 62 is specified by the connection path 30 from the time when the loop detection section 70 detects that the radius of curvature of the document D has reached the limit value of the radius of curvature specified by the connection path 30. By performing the first control to stop the second drive motor 91 until it is detected that the radius of curvature of the original D falls within the range of the radius of curvature, the radius of curvature of the document D can be reduced in a short time.
In the range of the radius of curvature defined by Alternatively, the control unit 62 determines the radius of curvature defined by the control unit 62 from when the loop detection unit 70 detects that the radius of curvature of the document D has reached the limit value of the radius of curvature defined by the control unit 62. Until it is detected that the rotation speed is within the range, the rotation speed of the second drive motor 91 is decreased to change the speed ratio between the rotation speed of the first drive motor 81 and the rotation speed of the second drive motor 91. Is performed, the radius of curvature of the document D can be kept within the range of the radius of curvature defined by the connection path 30 without interrupting the image reading of the document D.

[0033]

As described above, according to the image reading apparatus of the first aspect, the rear end of the original document conveyed by the first conveying means and the front end side of the document conveyed by the second conveying means are read. A loop detecting means for detecting a change in the radius of curvature in the connection path, and when it is detected that the radius of curvature of the document has reached the limit value of the radius of curvature defined by the connection path, Control means for changing the rotation speed of the first drive motor or the second drive motor so that the document falls within the range of the radius of curvature defined by the connection path, thereby providing the first drive motor or The transport speed of the first transport unit and the speed of the second transport motor are changed due to an error in the drive pulse output to the second drive motor.
Even if the conveyance speeds of the conveyance means do not match, and the radius of curvature of the document reaches the limit value of the radius of curvature defined by the connection path, the document can be returned within the range of the radius of curvature specified by the connection path. For example, it is possible to prevent a load variation on the first drive motor or the second drive motor due to the generation of tension due to the document being pressed against the connection path, and to reduce the transport speed by the second transport unit when reading the document. Fluctuation can be prevented. As a result, the image reading unit can reliably scan the image surface at predetermined pitches with respect to the document, and a reading error occurs due to a change in the transport speed of the document, and the image quality of the reproduced image is reduced. It can be prevented from lowering.

Further, according to the image reading apparatus of the second aspect, the control means detects that the radius of curvature of the document has reached the limit value of the radius of curvature defined by the connection path by the loop detecting means. By stopping one of the first drive motor and the second drive motor from the time until it is detected that the radius falls within the range of the radius of curvature defined by the connection path, the radius of curvature of the document can be reduced in a short time. It can be within the range of the radius of curvature defined by the connection path.

Further, according to the image reading apparatus of the third aspect, the control means detects that the radius of curvature of the document has reached the limit value of the radius of curvature defined by the connection path by the loop detecting means. By changing the speed ratio between the rotation speed of the first drive motor and the rotation speed of the second drive motor from time to until it is detected that the radius of curvature is within the range of the radius of curvature defined by the connection path, The radius of curvature of the document can be kept within the range of the radius of curvature defined by the connection path without interrupting image reading of the document.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an embodiment of an image reading apparatus according to the present invention.

FIG. 2 is a perspective view illustrating a transport mechanism in the image reading apparatus according to the embodiment.

FIG. 3 is a cross-sectional view illustrating the configuration and operation of a loop detection unit in the image reading device according to the embodiment.

FIG. 4 is a schematic configuration diagram of a facsimile apparatus to which a conventional image reading apparatus is applied.

FIG. 5 is a configuration diagram schematically showing a conventional image reading apparatus and a perspective view showing a transport mechanism in the conventional image reading apparatus.

FIG. 6 is a configuration diagram schematically showing a conventional image reading apparatus and a perspective view showing a transport mechanism in the conventional image reading apparatus.

FIG. 7 is an explanatory diagram of a transport speed when a transport mechanism is driven by two drive motors in a conventional image reading apparatus.

FIG. 8 is a flowchart showing control of a control unit for a drive motor in the image reading apparatus of the embodiment.

FIG. 9 is a flowchart illustrating control of a control unit for a drive motor in the image reading apparatus according to the embodiment.

[Explanation of symbols]

14: first transport path, 17: scanner unit, 18: second transport path, 19: white reference plate, 28: outer guide plate, 29: inner guide plate, 30: connection path, 51: pickup roller,
52: Feed roller, 53: Separation roller, 54, 56,
58… Conveying rollers, 55, 57, 58, 61… Pressurizing rollers, 60…
Discharge roller, 62 ... Control unit, 70 ... Loop detection unit, 71
... Holder, 72 ... Micro switch, 81 ... First drive motor, 91 ... Second drive motor, D ... Document.

Claims (3)

[Claims] A first drive motor, first transport means disposed in a first transport path and transporting the original by torque transmitted from the first drive motor, and a second drive motor; A second transport unit that is disposed on a second transport path and transports a document by torque transmitted from the second drive motor, and connects the first transport path to the second transport path; Scanning a curved connection path for guiding the document sent from the first conveyance path to the second conveyance path, and an image surface of the document conveyed in the second conveyance path by the second conveyance means; An image reading device for reading the image, wherein a radius of curvature of a document whose rear end is conveyed by the first conveying unit and whose front end is conveyed by the second conveying unit is within the connection path. Loop detection means for detecting changes in When the loop detecting means detects that the radius of curvature of the document has reached the limit value of the radius of curvature defined by the connection path, the document is within the range of the radius of curvature defined by the connection path. An image reading apparatus, further comprising control means for changing a rotation speed of the first drive motor or the second drive motor. 2. The control device according to claim 1, wherein the control unit detects that the radius of curvature of the document has reached a limit value of the radius of curvature defined by the connection path by the loop detection unit. 2. The image reading apparatus according to claim 1, wherein one of the first drive motor and the second drive motor is stopped until it is detected that the value falls within the range. 3. The control device according to claim 1, wherein the control unit detects that the radius of curvature of the original document has reached a limit value of the radius of curvature defined by the connection path. The rotation speed of the first drive motor and the rotation speed of the second
2. The image reading apparatus according to claim 1, wherein a speed ratio with respect to a rotation speed of the driving motor is changed.