JP6713817B2 - Image reading apparatus and image forming apparatus including the same - Google Patents

Description

The present invention relates to an image reading apparatus including a registration roller and a clutch that switches between rotation and stop of the registration roller and an image forming apparatus including the image reading apparatus.

In the conventional image reading apparatus, in order to convey the next original document waiting by the registration roller to the reading position of the first reading unit regardless of the single-sided reading mode or the double-sided reading mode in the reading operation of the original document, When the driving is started, the clutch is turned on and the rotational driving force is transmitted to the registration rollers.

In this case, since the load fluctuation when the clutch is turned on is largely received, the drive shake of the drive motor (DC motor) occurs, and the feed shake of the preceding document occurs.

This feed deviation of the preceding document does not cause a problem in the single-sided reading mode, but in the double-sided reading mode, the preceding document is the image data on the back side at the reading position of the second reading unit. Since the error occurs when the image is being read, there is a problem that the reading of the image data on the back side of the document is hindered.

By the way, as a technique for reducing load fluctuations when the clutch is turned on, Japanese Patent Application Laid-Open No. 2004-242242 discloses that in order to prevent vibration of the carriage of the scanner, when the clutch is activated to stop/drive the carriage (starting movement of the carriage). It is disclosed that the duty control is performed at the time.

JP-A-4-182677

However, the upper limit number of ON/OFF switching of the clutch is determined in consideration of durability, etc. If the ON/OFF switching is repeated too often, the determined upper limit number of times is reached early, and the clutch life is extended. There is a problem that it becomes shorter. Therefore, it is better to reduce the number of times the clutch is turned on and off as much as possible.

However, in Patent Document 1, since the duty of the clutch is always controlled when the carriage is driven, there is a problem that the life of the clutch is shortened.

The present invention was devised to solve the above problems, and an object thereof is to perform duty control of the clutch in the image reading apparatus when the clutch is turned on when the registration roller is driven. Considering that it may be possible to operate the clutch without turning it on, it is possible to prevent drive runout (that is, document feed runout) and to increase the clutch life by controlling the duty of the clutch only when necessary. An object of the present invention is to provide an improved image reading device and an image forming apparatus including the image reading device.

In order to solve the above-mentioned problems, an image reading apparatus of the present invention includes a first reading unit that reads a first surface of a document to be conveyed at a first reading position, and a second reading unit downstream of the first reading position in the conveyance direction. A second reading unit for reading the second side of the document provided with a reading position, a registration roller provided upstream of the first reading position in the transport direction, and a switch between rotation and stop of the registration roller is turned on. and a clutch performed by switching off, when rotating the registration roller by turning on the clutch, the second when there is the document conveyed to the reading position, the clutch oN / oFF About performs duty control, when rotating the registration roller by turning on the clutch, when the no document which has been conveyed to the second reading position, as characterized by an on control said clutch There is.

Further, according to the image reading apparatus of the present invention, the first reading unit that reads the first surface of the conveyed document at the first reading position and the second reading position on the downstream side of the first reading position in the carrying direction. A second reading unit for reading the second surface of the document provided, a registration roller provided upstream of the first reading position in the conveyance direction, and switching between rotation and stop of the registration roller on and off. a clutch performed by switching, when the double-sided reading mode is selected, performs the duty control for the on / off the clutch, the one-side reading mode selected when rotating the registration roller by turning on the clutch In this case, when the clutch is turned on and the registration roller is rotated, the clutch is turned on.

Further, according to the image reading apparatus of the present invention, when the double-sided reading mode is selected, when the clutch is turned on and the registration roller is rotated, the document conveyed to the second reading position is If not, the clutch may be in the on control.

Further, according to the image reading apparatus of the present invention, the start timing of the duty control may be earlier than the start timing of the on control of the clutch when the clutch is turned on to rotate the registration roller.

Further, according to the image reading apparatus of the present invention, the duty control may be configured to gradually increase the time for which the clutch is turned on.

An image forming apparatus of the present invention is characterized by including the image reading apparatus having each of the above configurations.

According to the present invention, when the document is read by the second reading unit, it is possible to reduce the feed shake of the document.

FIG. 1 is a partial schematic cross-sectional view showing an overall configuration of an image forming apparatus according to the present invention. FIG. 1 is a perspective view showing an overall appearance of a document reading apparatus according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a document reading device. FIG. 3 is a block diagram schematically showing a main part of an electrical configuration of the document reading device. 9 is a timing chart of clutch on/off control in the conventional document conveyance control by the document movement method in the double-sided reading mode. 6 is a timing chart of document conveyance control according to the first embodiment. 9 is a timing chart of document conveyance control according to the second embodiment. 9 is a timing chart of document conveyance control according to the third embodiment. 9 is a timing chart of document conveyance control according to the fourth embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiments are examples of embodying the present invention, and are not of the nature to limit the technical scope of the present invention.

[Description of Configuration of Image Forming Apparatus]
FIG. 1 is a partial schematic sectional view showing the overall configuration of an image forming apparatus equipped with an image reading apparatus according to the present invention.

The image forming apparatus 300 includes an image reading apparatus 100 that reads an image from a document and an apparatus main body (image forming unit) 200 that forms an image read by the image reading apparatus 100 on a recording sheet that is a recording medium. There is. FIG. 1 shows the configuration of the image forming apparatus when viewed from the front.

The apparatus main body 200 includes a photosensitive drum 221, a charger 222, an exposure device 223, a developing device 224, a transfer device 225, a fixing device 226, a paper feed tray 227, and the like. In the apparatus main body 200 having such a configuration, an image is formed on a recording sheet as follows.

First, the surface of the photoconductor drum 221 charged by the charger 222 is exposed by the exposure device 223 according to the image read by the image reading device 100, so that an electrostatic latent image is formed on the surface of the photoconductor drum 221. It is formed. Next, the developing device 224 develops the electrostatic latent image formed on the photosensitive drum 221 with toner. The toner image thus formed on the photosensitive drum 221 is transferred onto the transfer belt provided in the transfer device 225, and the toner image on the transfer belt is transferred onto the recording paper supplied from the paper feed tray 227. To be done. By heating the recording sheet by the fixing device 226, the toner image formed on the recording sheet is melted and mixed, and at the same time, the toner image is pressed against the recording sheet. The recording paper on which the toner image is fixed is discharged onto a paper discharge tray 228 provided in the apparatus main body 200.

The image reading device 100 is arranged above the device main body 200. Further, above the image reading apparatus 100, the automatic document feeder 1 which functions as a cover of the document table is arranged.

[Description of Configuration of Image Reading Device]
FIG. 2 is a perspective view showing an overall appearance of an image reading apparatus (hereinafter referred to as a document reading apparatus) 100 according to the embodiment of the present invention. 3 is a sectional view showing a schematic configuration of the document reading apparatus 100 shown in FIG.

The document reading apparatus 100 includes an automatic document feeder (hereinafter, referred to as “ADF”) 1 that automatically conveys a document P along a document conveyance path F, and a conveyed document P or a positioned document P. First reading unit 10 for reading an image on the front surface (first surface) side of the document, and second reading unit 20 for reading an image on the back surface (second surface) of the document P provided on the downstream side of the first reading unit 10. It has and. When reading the image of the positioned original P, the first reading unit 10 optically scans the original P while irradiating the original P with the light source 11, and forms an image of the reflected light from the original P. It is configured to read as data. Specifically, the first reading unit 10 is a reduction optical system including a light source 11, a mirror group (here, first to third mirrors 12a, 12b, and 12c), a lens 13, and an image sensor 14 such as a CCD (image sensor). This is the reading part of the system. The second reading unit 20 is a reduction optical system including a light source 21, a mirror group (here, first to fourth mirrors 22a, 22b, 22c, 22d), a lens 23, and an image sensor 24 such as a CCD (image sensor). Is the reading section of. The second reading unit 20 is unitized so that the light source 21, the first to fourth mirrors 22a, 22b, 22c, 22d, the lens 23, and the image pickup device 24 form one assembly.

The document reading device 100 mainly includes an ADF 1 that houses the second reading unit 20, and a document scanning unit 2 that houses the first reading unit 10.

The ADF 1 and the document scanning unit 2 are connected by a hinge (not shown), and the ADF 1 can be opened and closed with respect to the document scanning unit 2 by rotating the hinge. The lower surface of the ADF 1 serves as a pressing plate 28 that presses the read original P placed on the platen plate 4 of the original scanning unit 2 from above.

The document scanning unit 2 mainly includes a housing 3, a platen plate 4 made of a transparent glass plate, a first reading unit 10 and a second reading unit 20 housed in the housing 3.

The first reading unit 10 mainly includes a light source unit 15 that holds the light source 11 and the first mirror 12a arranged at the first reading position 10a, a mirror unit 16 that holds the second mirror 12b and the third mirror 12c, a lens 13, and It is composed of the image sensor 14.

The document scanning unit 2 performs image reading by a document fixing method in which a user places the document P on the platen plate 4 to read the document image and moves the document by automatically feeding the document by the ADF 1 to read the document image. It supports both methods.

When reading a document image by the document fixing method, the light source unit 15 and the mirror unit 16 are respectively moved to home positions corresponding to the document fixing method. Thereafter, the light source unit 15 moves in the sub-scanning direction (X direction in the drawing) at a constant speed while irradiating the original P with light to scan the image of the original P, and at the same time, the mirror unit 16 causes the light source unit 15 to move. Similarly, it moves in the sub-scanning direction X at a moving speed that is 1/2 of the moving speed.

The reflected light from the document P illuminated by the light source 11 of the light source unit 15 is reflected by the first mirror 12a provided in the light source unit 15, and then 180 by the second and third mirrors 12b and 12c of the mirror unit 16. The light whose optical path has been changed and which is reflected from the third mirror 12c forms an image on the image pickup device 14 via the lens 13, where a document image is read and converted into electrical image data.

On the other hand, when reading a document image by the document moving method, the light source unit 15 and the mirror unit 16 remain stationary at the position shown in FIG. 3, and the ADF 1 passes the upper part of the position shown in FIG. The original P conveyed to X is irradiated with light from the light source 11 to scan the original image, and the light reflected from the front surface (first surface) side of the original P is the same as the original fixing method described above. After being reflected by the first mirror 12a, the optical path is changed by 180° by the second and third mirrors 12b and 12c of the mirror unit 16, and an image is formed on the image sensor 14 through the lens 13, where the original image is read. Converted to electrical image data.

The ADF 1 mainly includes a pair of feeding rollers 6 that feeds the originals P placed on the original placing table 5 into the main body one by one, and a plurality of pairs of conveying rollers 7 that conveys the called originals P along the original feeding path F. A registration roller 8 provided on the upstream side of the first reading unit 10 for adjusting the paper feed timing, and a paper ejection roller 9 for ejecting the document P after the image reading to the paper ejection tray 30 are formed into a unit second. The reading unit 20 is arranged so as to be accommodated in a document conveyance path F that draws an arc in a substantially U shape.

The second reading unit 20 mainly includes a light source holder 25 that holds the light source 21 arranged at the second reading position 20a, a first mirror 22a, a second mirror 22b, a third mirror 22c, a fourth mirror 22d, a lens 23, and an image pickup device. It is composed of the element 24, and each of these members is unitized by being housed in the unit casing 26 so as to form one aggregate. In addition, in the second reading unit 20, the light source 21, the lens 23, and the image pickup device 24 held by the light source holder 25 are the same as those configuring the first reading unit 10.

As described above, the second reading unit 20 reads the image on the back surface (second surface) of the document P conveyed through the document conveyance path F when the user makes a double-sided reading request. Specifically, after the image on the front surface (first surface) side of the document P is read by the first reading unit 10, the document P is directed along the document transport path F toward the discharge tray 30 in the sub-scanning direction. While being conveyed to X, it passes under the light source holder 25 of the second reading unit 20. At this time, the light source 21 of the second reading unit 20 emits light toward the back surface (second surface) side of the document P, and the light reflected from the back surface (second surface) side of the document P is After the optical paths are sequentially changed by the fourth mirrors 22a, 22b, 22c, and 22d, an image is formed on the image pickup device 24 through the lens 23, where a document image is read and converted into electric image data.

FIG. 4 is a block diagram schematically showing a main part of an electrical configuration of the document reading apparatus 100 shown in FIGS. 2 and 3.

The document reading apparatus 100 shown in FIGS. 2 and 3 mainly drives and controls the control unit 101, the scanner unit 102, the image processing unit 103, the storage unit 104, the communication unit 105, the operation panel unit 106, and the document scanning unit drive motor 107a. The driver 107 and the driver 108 for controlling the driving of the document feeding unit drive motor 108a are included.

The control unit 101 is a unit that manages operation control of the entire apparatus, and is configured by a CPU, a ROM, a RAM, and the like, although not shown.

The scanner unit 102 constitutes an optical scanning system of the first and second reading units 10 and 20 shown in FIG. The image pickup devices 14 and 24 of the first and second reading units 10 and 20 may be CCDs of the optical reduction system as described above, or may be CISs (Contact Image Sensors) of the equal magnification optical system.

The image processing unit 103 converts the optical data read by the first reading unit 10 or the second reading unit 20 into electrical image data page by page.

The storage unit 104 is composed of, for example, a RAM, an EEPROM, a hard disk, an MO, etc., and stores the data under control controlled by the control unit 101 and various input instruction contents. The storage unit 104 also has an area that functions as a document image storage unit that stores a document image read by the scanner unit 102 and a document storage unit that stores a document including a code of a converted character string.

The communication unit 105 is a communication unit that performs bidirectional communication with an external device 400 such as a connected computer or printer, and transmits the data image-processed by the image processing unit 103 to the external device 400. Further, it is provided with a memory for expanding the data transmitted from the external device 400 into data that can be handled by this apparatus.

The operation panel unit 106 is arranged on the front side of the document reading apparatus 100 shown in FIG. 2 (see FIG. 1). Specifically, the original scanning unit 2 is extended to the front side of the ADF 1 and is arranged on the upper surface portion thereof. The operation panel unit 106 includes an input unit that can be manually operated to give an instruction to start reading a document.

The document scanning unit driving motor 107a is a motor (DC motor) for moving the light source unit 15 and the mirror unit 16 in the sub-scanning direction X at an appropriate speed when reading a document image by a document fixing method. Under the control of 101, the drive is appropriately controlled by the driver 107.

The document conveyance unit drive motor 108 a is a motor (DC motor) that drives each of the rollers such as the introduction roller 6, the conveyance roller 7, the registration roller 8, and the paper discharge roller 9 arranged in the document conveyance path F, and the control unit 101. The drive is controlled by the driver 108 as appropriate. Further, a clutch 109 for switching between rotation and stop of the registration roller 8 is interposed between the document conveying unit drive motor 108a and the registration roller 8, and by the clutch on/off control of the control unit 101, The rotation/stop of the registration roller 8 is controlled. That is, when the clutch is turned on, the registration roller 8 starts rotating, and when the clutch is turned off, the registration roller 8 stops rotating.

[Description of document conveyance control by document movement method in duplex scanning mode]
Next, in the document reading apparatus 100 shown in FIG. 2 and FIG. 3, document feeding control by a document moving method in the double-sided reading mode will be described.

First, the conventional document conveyance control by the document movement method in the double-sided reading mode will be described, and then the document conveyance control by the document movement method in the double-sided reading mode according to the embodiment of the present invention will be described.

(Description of conventional document transport control)
FIG. 5 is a timing chart of on/off control of the clutch 109 in the conventional document conveyance control by the document movement method in the double-sided reading mode.

In the double-sided reading mode, from the original P placed on the original placing table 5, the first original P is called into the original conveyance path F by the introduction roller 6, and is conveyed by the conveyance roller 7 to the registration roller 8. It is stopped here. Then, the clutch 109 is turned on to start the rotation of the registration roller 8 at the timing t1 when the start of reading the original is in the Ready state, and the first surface of the first original P reaching the first reading position 10a is moved to the first side. 1 Read by the reading unit 10. After that, the document P whose first surface has been read is further transported to the paper discharge tray 30 side by the transport roller 7, and when the second surface of the document P is read by the second reading unit 20, the paper discharge roller 9 is used. The sheet is discharged to the sheet discharge tray 30.

On the other hand, when the registration roller 8 starts to convey the first original P, the second original P on the original placing table 5 is called into the original conveying path F by the take-in roller 6, and the conveying roller 7 moves. Is conveyed to the registration roller 8 and is temporarily stopped there. Then, at the timing t1 when the start of reading the original becomes the Ready state, the clutch 109 is turned on to start the rotation of the registration roller 8, and the first reading unit 10 starts reading the first surface of the second original P. To do. At this time, the preceding first document P is located at the second reading position 20a, and the second reading unit 20 is in the process of reading the second surface. Therefore, as described in the above background art, the load fluctuation when the clutch 109 is turned on causes the feed shake of the preceding first document P, and the second surface of the second reading unit 20. Reading will be hindered. Therefore, in order to solve such a problem, the present invention performs the following document conveyance control. The details will be described below.

(Description of Document Conveyance Control According to First Embodiment)
FIG. 6 is a timing chart of the document conveyance control according to the first embodiment.

In the double-sided reading mode, from the original P placed on the original placing table 5, the first original P is called into the original conveyance path F by the introduction roller 6, and is conveyed by the conveyance roller 7 to the registration roller 8. It is stopped here. Then, the clutch 109 is turned on to start the rotation of the registration roller 8 at the timing t1 when the start of reading the original is in the Ready state, and the first surface of the first original P reaching the first reading position 10a is moved to the first side. 1 Read by the reading unit 10. That is, the ON control of the clutch 109 at the time of reading the first surface of the first original P is the same as that of the conventional original conveyance control. That is, when the first surface of the first original P is being read, the original P does not exist at the second reading position 20a of the second reading unit 20, so the load fluctuation due to the ON operation (ON control) of the clutch 109. Even if the error occurs, the second reading unit 20 does not hinder the reading of the document.

After that, the document P whose first surface has been read is further transported to the paper discharge tray 30 side by the transport roller 7, and when the second surface of the document P is read by the second reading unit 20, the paper discharge roller 9 is used. The sheet is discharged to the sheet discharge tray 30.

On the other hand, when the registration roller 8 starts to convey the first original P, the second original P on the original placing table 5 is called into the original conveying path F by the take-in roller 6, and the conveying roller 7 Is conveyed to the registration roller 8 and is temporarily stopped there. Then, the clutch 109 is turned on (on control) at the timing t1 when the start of reading the original is in the Ready state. Until the time reaches t1, the on/off duty control of the clutch 109 is performed.

Specifically, in the first embodiment, duty control is performed in which 1 ms on and 1 ms off are repeated for 2 cycles from 13 ms before the timing t1, and then 2 ms on and 1 ms off are repeated for 3 cycles. Then, thereafter, as in the conventional case, the control is switched to the ON control at the timing t1, and the registration roller 8 is continued at a constant rotation speed. The duty control of turning on/off when the clutch 109 is turned on is applied to all the originals P after the second sheet.

In the first embodiment, the on/off duty control of the clutch 109 is configured to gradually increase the on time (in the first embodiment, the configuration is changed from 1 ms to 2 ms in two stages). According to this configuration, the rotation of the registration roller 8 can be gradually increased, so that it is possible to reduce the load fluctuation when the clutch 109 is turned on. As a result, the feed shake of the preceding first document P is reduced, and the second surface of the first document P can be read without any trouble.

Further, in the first embodiment, the period from the timing t2 to the timing t1 when the original reading start becomes the Ready state is 13 ms, but it is about 95 ms from the timing t1 to the original reading start timing.

(Description of Document Conveyance Control According to Second Embodiment)
FIG. 7 is a timing chart of document conveyance control according to the second embodiment.

In the first embodiment, the on/off duty control of the clutch 109 is performed from the stage (timing t2) before the timing t1 by a predetermined time until the timing t1 is reached, and after the timing t1, the clutch 109 is turned on as usual. It is in control. In this case, from the stage before the timing t1, the document P is slightly conveyed by the on/off duty control of the clutch 109. Therefore, there is a possibility that the document is slightly conveyed before the reading start timing of the first reading unit 10.

Therefore, in the second embodiment, in consideration of this point, the on/off duty control of the clutch 109 is performed from the stage (timing t3) that is a predetermined time before the timing t1 to the timing t4, which is a little after the timing t1. ing. That is, the start timing of the ON/OFF duty control is slightly delayed as compared with the case of the first embodiment.

In the double-sided reading mode, from the original P placed on the original placing table 5, the first original P is called into the original conveyance path F by the introduction roller 6, and is conveyed by the conveyance roller 7 to the registration roller 8. It is stopped here. Then, the clutch 109 is turned on to start the rotation of the registration roller 8 at the timing t1 when the start of reading the original is in the Ready state, and the first surface of the first original P reaching the first reading position 10a is moved to the first side. 1 Read by the reading unit 10. That is, the ON control of the clutch 109 at the time of reading the first surface of the first original P is similar to the conventional original conveyance control and the original conveyance control of the first embodiment. After that, the document P whose first surface has been read is further transported to the paper discharge tray 30 side by the transport roller 7, and when the second surface of the document P is read by the second reading unit 20, the paper discharge roller 9 is used. The sheet is discharged to the sheet discharge tray 30.

On the other hand, when the registration roller 8 starts to convey the first original P, the second original P on the original placing table 5 is called into the original conveying path F by the take-in roller 6, and the conveying roller 7 Is conveyed to the registration roller 8 and is temporarily stopped there. Then, the clutch 109 is turned on (on control) in synchronization with the timing t1 when the start of reading the original is in the Ready state. The duty control for turning on/off the clutch 109 is performed from the time t1 to the time t4 slightly after the timing t1.

Specifically, in the second embodiment, the duty control is repeated such that 1 ms on and 1 ms off are repeated for 2 cycles from timing t3, which is 10 ms before the timing t1, and then 2 ms on and 1 ms off are repeated for 3 cycles. Until timing t4. Then, after the timing t4, the control is switched to the ON control as in the conventional case, and the registration roller 8 is continued at a constant rotation speed. The duty control of turning on/off when the clutch 109 is turned on is applied to all the second and subsequent originals P.

Also in the second embodiment, the ON/OFF duty control of the clutch 109 is configured to gradually increase the ON time. According to this configuration, the rotation of the registration roller 8 can be gradually increased, so that it is possible to reduce the load fluctuation when the clutch 109 is turned on. As a result, the feed shake of the preceding first document P is reduced, and the second surface of the first document P can be read without any trouble.

According to the second embodiment, the on-control timing t4 of the clutch 109 is slightly delayed (3 ms in this example) from the conventional on-control timing t1. In this way, by slightly delaying the timing t4 of the ON control of the clutch 109, it is possible to adjust the reading start timing by the first reading unit 10 and the document conveyance timing so as to coincide with each other.

In the first and second embodiments, a configuration in which the on-time is gradually increased is changed to two stages from 1 ms to 2 ms. However, this is merely an example, and the configuration may be changed more finely, for example, in three stages of 1 ms to 1.5 ms and 1.5 ms to 2 ms. Furthermore, the configuration may be changed more finely.

(Description of Document Conveyance Control According to Third Embodiment)
FIG. 8 is a timing chart of document conveyance control according to the third embodiment.

In the first and second embodiments, the ON time during duty control is gradually lengthened, but in the third embodiment, in addition to this, the OFF time during duty control is gradually shortened.

In the double-sided reading mode, from the original P placed on the original placing table 5, the first original P is called into the original conveyance path F by the introduction roller 6, and is conveyed by the conveyance roller 7 to the registration roller 8. It is stopped here. Then, the clutch 109 is turned on to start the rotation of the registration roller 8 at the timing t1 when the start of reading the original is in the Ready state, and the first surface of the first original P reaching the first reading position 10a is moved to the first side. 1 Read by the reading unit 10. That is, the ON control of the clutch 109 at the time of reading the first surface of the first original P is similar to the conventional original conveyance control and the original conveyance control of the first and second embodiments. After that, the document P whose first surface has been read is further transported to the paper discharge tray 30 side by the transport roller 7, and when the second surface of the document P is read by the second reading unit 20, the paper discharge roller 9 is used. The sheet is discharged to the sheet discharge tray 30.

On the other hand, when the registration roller 8 starts to convey the first original P, the second original P on the original placing table 5 is called into the original conveying path F by the take-in roller 6, and the conveying roller 7 moves. Is conveyed to the registration roller 8 and is temporarily stopped there. Then, the clutch 109 is turned on (on control) at the timing t1 when the start of reading the original is in the Ready state. Until the time reaches t1, the on/off duty control of the clutch 109 is performed.

Specifically, in the third embodiment, duty control is performed until timing t1 in which 1 ms on and 1 ms off are repeated for 2 cycles from timing t5 before timing t1 and then 2 ms on and 0.5 ms off are repeated for 3 cycles. Then, after the timing t1, as in the conventional case, the control is switched to the ON control, and the registration roller 8 is continued at a constant rotation speed. The duty control of turning on/off when the clutch 109 is turned on is applied to all the second and subsequent originals P.

In the third embodiment, the on/off duty control of the clutch 109 is configured to gradually increase the on time and gradually decrease the off time. According to this configuration, the rotation of the registration roller 8 can be gradually increased, so that it is possible to reduce the load fluctuation when the clutch 109 is turned on. As a result, the feed shake of the preceding first document P is reduced, and the second surface of the first document P can be read without any trouble.

(Description of Document Conveyance Control According to Fourth Embodiment)
FIG. 9 is a timing chart of document conveyance control according to the fourth embodiment.

In the third embodiment, the on/off duty control of the clutch 109 is performed from the stage (timing t5) before the timing t1 by a predetermined time to the timing t1, and after the timing t1, the clutch 109 is turned on as usual. It is in control. In this case, from the stage before the timing t1, the document P is slightly conveyed by the ON/OFF duty control of the clutch 109. Therefore, there is a possibility that the document is slightly conveyed before the reading start timing of the first reading unit 10.

Therefore, in the fourth embodiment, in consideration of this point, the duty control of the on/off of the clutch 109 is performed from the stage (timing t6) before the timing t1 by the predetermined time to the timing t7 which slightly passes the timing t1. ing. That is, the start timing of the on/off duty control is slightly delayed compared to the case of the third embodiment.

In the double-sided reading mode, from the original P placed on the original placing table 5, the first original P is called into the original conveyance path F by the introduction roller 6, and is conveyed by the conveyance roller 7 to the registration roller 8. It is stopped here. Then, the clutch 109 is turned on to start the rotation of the registration roller 8 at the timing t1 when the start of reading the original is in the Ready state, and the first surface of the first original P reaching the first reading position 10a is moved to the first side. 1 Read by the reading unit 10. That is, the ON control of the clutch 109 at the time of reading the first surface of the first original P is similar to the conventional original conveyance control and the original conveyance control of the first to third embodiments. After that, the document P whose first surface has been read is further transported to the paper discharge tray 30 side by the transport roller 7, and when the second surface of the document P is read by the second reading unit 20, the paper discharge roller 9 is used. The sheet is discharged to the sheet discharge tray 30.

On the other hand, when the registration roller 8 starts to convey the first original P, the second original P on the original placing table 5 is called into the original conveying path F by the take-in roller 6, and the conveying roller 7 Is conveyed to the registration roller 8 and is temporarily stopped there. Then, the clutch 109 is turned on (controlled) in synchronization with the timing t1 when the start of reading the original is in the Ready state. At this time, in the fourth embodiment, the timing t1 is shifted from the timing t6 which is a predetermined time before the timing t1. The duty control of the on/off of the clutch 109 is performed until the timing t7, which has passed a little after, reaches the timing t7.

Specifically, in the fourth embodiment, the duty control in which 1 ms on and 1 ms off are repeated for 2 cycles from timing t6 before timing t1 and then 2 ms on and 0.5 ms off are repeated for 3 cycles is performed slightly after timing t1. Until timing t7. Then, after the timing t7, the control is switched to the ON control as in the conventional case, and the registration roller 8 is continued at a constant rotation speed. The duty control of turning on/off when the clutch 109 is turned on is applied to all the originals P after the second sheet.

Also in the fourth embodiment, the on/off duty control of the clutch 109 is configured such that the on time is gradually lengthened and the off time is gradually shortened. According to this configuration, the rotation of the registration roller 8 can be gradually increased, so that it is possible to reduce the load fluctuation when the clutch 109 is turned on. As a result, the feed shake of the preceding first document P is reduced, and the second surface can be read by the second reading unit without any trouble.

According to the fourth embodiment, the on-control timing t7 of the clutch 109 is slightly delayed (2.5 ms in this example) from the conventional on-control timing t1. In this way, by slightly delaying the timing t7 of the on control of the clutch 109, it is possible to adjust the reading start timing by the first reading unit 10 and the document conveyance timing so that they coincide with each other.

In the third and fourth embodiments, a configuration in which the ON time is gradually increased is changed to two stages from 1 ms to 2 ms, and an OFF time is gradually reduced in the 2 stages from 1 ms to 0.5 ms. The structure which changes to a stage is illustrated. However, this is just an example, and more detailed, for example, a configuration in which the on-time is changed in 3 steps from 1 ms to 1.5 ms and 1.5 ms to 2 ms, and the off-time is changed from 1 ms to 0.7 ms and 0.7 ms. The configuration may be changed to three steps of 0.4 ms. Furthermore, the configuration may be changed more finely.

[Summary]
As described above, according to the image reading apparatus of the present invention, when the clutch 109 is turned on and the registration roller 8 is rotated, there is a document conveyed to the second reading position 20a (the second and subsequent sheets). When the clutch 109 is turned on/off to control the duty and the registration roller 8 is rotated, there is no document conveyed to the second reading position 20a (for example, 1). In the case of the first document), the clutch 109 is controlled to be turned on.

According to this configuration, it is possible to reduce the feed shake of the document P when the document P is read by the second reading unit 20.

Further, according to the image reading apparatus of the present invention, when the double-sided reading mode is selected, when the clutch 109 is turned on and the registration roller 8 is rotated, the clutch 8 is subjected to on/off duty control, and one-sided When the reading mode is selected, the clutch 109 may be turned on to turn on the clutch 109 when the registration roller 8 is rotated.

According to this configuration, it is possible to reduce the feed shake of the original when the second reading unit reads the original.

Further, according to the image reading apparatus of the present invention, when the double-sided reading mode is selected, when the clutch 109 is turned on and the registration roller 8 is rotated, there is no document conveyed to the second reading position 20a. Alternatively, the clutch 109 may be turned on.

According to this configuration, it is possible to reduce wear of the clutch due to ON/OFF duty control as much as possible. That is, since the upper limit number of on/off switchings of the clutch is determined by the manufacturer or the like, it is possible to prolong the life of the clutch by not performing the duty control of the on/off of the clutch unless it is necessary. it can.

Further, according to the image reading apparatus of the present invention, the start timing of the on/off duty control of the clutch 109 is determined from the start timing of the on control of the clutch 109 when the clutch 109 is turned on to rotate the registration roller 8. It may be configured early.

With this configuration, it is possible to match the actual document conveyance start timing with the timing when the clutch is on-controlled.

The present invention can be embodied in various other forms without departing from the spirit or the main characteristics thereof. Therefore, the above-described embodiments are merely examples in all respects, and should not be limitedly interpreted. The scope of the present invention is shown in the claims, and is not restricted by the text of the specification. Furthermore, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

1 Automatic Document Feeder (ADF)
2 Original Scanning Section 4 Platen Plate 5 Original Placement Table 6 Invitation Roller 7 Conveying Roller 8 Registration Roller 9 Ejection Roller 10 First Reading Section 10a First Reading Position 20 Second Reading Section 20a Second Reading Position 100 Original Reading Device (Image Reader)
Reference numeral 101 control unit 102 scanner unit 103 image processing unit 104 storage unit 105 communication unit 106 operation panel unit 107, 108 driver 107a document scanning unit drive motor 108a document transportation unit drive motor 109 clutch 200 device body (image forming unit)
300 Image forming device P manuscript

Claims (6)

A first reading unit for reading the first surface of the conveyed document at a first reading position, and a second reading unit for reading the second surface of the document having a second reading position downstream of the first reading position in the conveyance direction. A reading unit; a registration roller provided upstream of the first reading position in the transport direction; and a clutch for switching between rotation and stop of the registration roller by switching on and off.
When rotating the registration roller by turning on the clutch, when there is the document which has been conveyed to the second reading position, performs the duty control for the on / off said clutch, and on the clutch when rotating the registration roller Te, the second when no reading the document conveyed to the position, the image reading apparatus characterized by turning on controlling the clutch. A first reading unit for reading the first surface of the conveyed document at a first reading position, and a second reading unit for reading the second surface of the document having a second reading position downstream of the first reading position in the conveyance direction. A reading unit; a registration roller provided upstream of the first reading position in the transport direction; and a clutch for switching between rotation and stop of the registration roller by switching on and off.
When the double-sided reading mode is selected , duty control is performed for turning on/off the clutch when the clutch is turned on and the registration roller is rotated, and when the single-sided reading mode is selected, the clutch is turned on. image reading apparatus characterized by turning on controlling the clutch when turned on to rotate the registration roller. The image reading apparatus according to claim 2, wherein
When the double-sided reading mode is selected, when the document is not conveyed to the second reading position when the clutch is turned on and the registration roller is rotated, the clutch is set to the ON control. An image reading device characterized by: The image reading device according to any one of claims 1 to 3,
The image reading apparatus is characterized in that the start timing of the duty control is earlier than the start timing of the on control of the clutch when the clutch is turned on to rotate the registration roller. The image reading apparatus according to any one of claims 1 to 4,
In the image reading apparatus, the duty control gradually lengthens a time for which the clutch is turned on. An image forming apparatus comprising the image reading device according to any one of claims 1 to 5.

Images