JP2853391B2 - Image reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original transporting apparatus in a movable original reading apparatus, and more particularly, to an original transporting apparatus by adjusting a driving speed of a transport roller unit disposed in an image scanning apparatus and a platen roller. The present invention relates to an image reading apparatus that scans a document without causing slack or the like.

[0002]

2. Description of the Related Art An image reading unit in a facsimile,
As an image reading means arranged in an image reading unit of an electronic copying machine or the like, for example, as shown in Japanese Patent Application Laid-Open No. 2-64393, a document is placed on a platen, and scanning is performed while moving the lower portion of the platen. Type devices are used. An image reading device provided in the electronic copying machine transmits light scanned on a document directly to a photosensitive drum to write an image. In contrast, for example,
In an image reading apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 2-304582 or the like, light obtained by scanning a document is converted into a digital signal,
Means for outputting the signal to an image writing device and writing an image on a photosensitive drum is also used. The image reading apparatus configured as described above uses a method of scanning while moving the scanning device in a state where the document is stopped and held on the platen.

In addition to the above-described scanning device, a method of arranging the scanning device at a fixed position and reading an image while moving a document with respect to the scanning device is also generally used in a device such as a facsimile. ing. For example, in a facsimile apparatus disclosed in Japanese Utility Model Publication No. 61-21890, an image scanning device is arranged in the middle of a document conveying path to scan a document image. In the image reading device, a transport roller device is disposed at an upstream portion and a downstream portion of a document transport path corresponding to a portion of the reading device of the image scanning device, and together with a platen roller disposed corresponding to the reading device, Means for driving the roller device at the same speed to convey the document and scan the image.

In the image reading apparatus provided in the facsimile, as shown in FIG. 6, a reading apparatus 12 is arranged on an image scanning apparatus 10 via a platen 11, and a platen roller 13 is arranged in correspondence with the platen 11. doing. An image is scanned by the reading device 12 while the back surface of the document is pressed by the platen roller 13 and the image surface of the document is moved while being pressed against the platen 11. Further, in the image reading apparatus shown in FIG. 6, all of the roller devices arranged with respect to the image scanning device 10 are driven by one drive motor 19, and the transport speed of the document by each roller device becomes the same. Thus, the drive mechanism is configured.

[0005]

However, as described above, when the roller devices arranged in the image scanning apparatus are set to the same driving speed, the degree of wear of the rollers, the roller and the paper In some cases, the conveyance speed of the document in each roller device is slightly different due to slippage or the like. If there is a roller with a low feed speed downstream of the roller with a high feed speed for the sheet, there is a problem that the sheet buckles between the two rollers. Therefore, the image surface of the document may be separated from the platen at that portion, and the read image may be out of focus.

Therefore, in order to solve the above-mentioned problem, as shown in Japanese Patent Publication No. 61-17773 and Japanese Utility Model Laid-Open Publication No. 62-100747, the driving speed for the roller device is made different. It has been proposed. In the conventional apparatus, when a roller device as shown in FIG. 6 is used, the discharge roller 17 is driven at a higher speed than the introduction roller 15 so that the document is pulled between both rollers, and the platen The roller 13 is pressed against the platen to scan an image. In the example shown in Japanese Utility Model Laid-Open No. 2-147445, the transport speed of the platen roller 13 in FIG. 6 is set to be higher than that of the transport roller devices 15 and 17.

However, as shown in the above-mentioned conventional example, in a device in which the drive speed of the roller device is set to be different, when the paper transport speed by the two transport roller devices is different, the trailing edge of the original is Immediately after the section has passed through the introduction roller 15, the speed of the document increases, causing a problem that the magnification of the information of the scanned image changes. In addition, when the speed of the platen roller is set to a high speed, the document buckles between the platen roller and the discharge side roller, and the document floats from the platen under the influence of the document, causing a focus defect and scanning. There is also a problem that a change in magnification occurs in the input image information.

As described above, in addition to the problem of the transport speed of the original by the transport roller device, the conventional transport roller device uses a rubber cylindrical member integrally attached to a shaft. However, the rubber roller member is
In addition to being prone to wear, it has the disadvantage of being vulnerable to oil. For example, when the roller is made of chloroprene rubber or the like and a paper coated with a special oil such as a slip sheet is used as a document, the oil applied to the slip adheres to the roller member. Then, the rubber member swells due to the oil and the diameter of the roller changes, which causes a problem that the feeding speed for the document does not meet the set value.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problem of the document conveying device in the conventional image reading apparatus, and to make it possible to move the image of the document close to the platen with the document surface being in close contact with the platen. It is another object of the present invention to provide an apparatus capable of maintaining a document feeding speed in an image scanning apparatus constant.

[0010]

According to the present invention, there is provided an image reading apparatus comprising: a platen arranged corresponding to a reading position of a document; a platen roller for conveying the document while pressing the document against the platen; A first drive roller disposed upstream of the platen roller and transporting the document, and a second drive roller disposed downstream of the platen roller and transporting the document, wherein the platen roller and the first In a state where the original is transported by the driving roller, the peripheral speed of the platen roller is relatively higher than the peripheral speed of the first driving roller to transport the original, and the platen roller and the second driving roller are transported. When the document is conveyed, the peripheral speed of the platen roller is relatively lower than the peripheral speed of the second drive roller, and the document is conveyed. And wherein the Rukoto.

[0011]

As described above, in the image reading apparatus of the present invention, when the document is being transported, the document is transported with the peripheral speed of the platen roller relatively higher than the peripheral speed of the first drive roller. In a state where the document is transported by the platen roller and the second drive roller on the downstream side, the document is transported with the peripheral speed of the platen roller relatively lower than the peripheral speed of the second drive roller. Therefore, it is possible to prevent the document from sagging or buckling in the image reading unit.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to the present invention will be described with reference to the illustrated example. The example shown in FIG. 1 shows an original moving type scanning device used for a facsimile or the like.
In the image scanning device 10, a reading device 12 is arranged below a platen 11, so that an image of a document passing through the portion of the image scanning device is read. In addition, the platen 1
A platen roller 13 is arranged corresponding to the upper surface of the document 1, and the document is conveyed while being pressed against the platen 11, so that the image can be scanned while the image surface of the document is in close contact with the platen. Roller driving device 14 provided in the image scanning device 10
In the figure, an introduction roller 15 provided with a first drive roller 16 is disposed upstream of the platen 11, and a discharge roller 17 provided with a second drive roller 18 is disposed downstream.
Further, in the image scanning device 10, the introduction-side roller 1
The sensor S is disposed between the platen 5 and the platen roller 13 to detect the passage of the document.

In the roller device provided in the image scanning device 10, the introduction roller 15 is a combination of a driving roller 16 and a pinch roller 16a.
Reference numeral 7 denotes a combination of a driving roller 18 and a pinch roller 18a. And with each roller device,
In a state where the document is nipped between the two rollers, an action of feeding the document is given. The transport roller device 15,
In the example shown in FIG. 1, two drive motors 19 and 19a are separately arranged with respect to the platen roller 17 and the platen roller 13, and the transport speed of each roller device is set by the drive motor. Note that, in the roller device, a transport roller device 1 disposed on both the upstream and downstream sides of the image scanning device is used.
Reference numerals 5 and 17 denote a unit that performs a conveying operation in a state where the original is strongly nipped, and a platen roller 13 is configured to apply a conveying operation by a frictional force between the original and the roller while pressing the original against the platen. Is done.

In the apparatus of the present invention configured as described above, in the roller device disposed in the image scanning device 10, as shown in a timing chart of FIG. The motor 19 is driven at a constant speed v1. On the other hand, the platen roller 13 is driven at a high speed v2 until the leading end of the document is nipped by the discharge side roller 17, and the document is moved between the introduction side roller 15 and the platen roller 13. The platen 11 is moved while being attracted. And
The position where the leading end of the document is detected by the sensor S and the leading end of the document is nipped by the discharge roller 17 is denoted by A. At a timing when the document passes through the point A, the platen roller 13 is driven at a low speed v3 to bring the document between the platen roller 13 and the discharge side roller 17 so that the document is conveyed.

As described above, the platen roller 13
In the state before the document is nipped by the discharge-side roller by changing the driving speed of the roller, the driving speed v1 <v2 of the roller device performing the driving operation on the sheet is satisfied. Therefore, the moving speed of the document at that portion is regulated by the transport speed by the introduction-side roller 15, and the scanning unit is moved while the document is pulled by the platen roller 13 driven at high speed. On the other hand, when the leading end of the document is nipped by the discharge roller 17, the driving speed of the driving motor 19 a with respect to the platen roller 13 is set to a low speed. Since v3 <v1, the original is placed on the discharge roller 1
7 and passes over the platen with the platen roller 13 applying a braking action.

Therefore, the roller driving device 14 provided in the image scanning apparatus of the present invention predicts the timing at which the leading end of the document is nipped by the discharge side roller after a predetermined time has elapsed since the detection of the document by the sensor S. Then, means for changing the driving speed for the platen roller is used. The document can be transported in a tensioned state without causing slack or buckling of the document passing through the image scanning device, and the document can be transported at a constant speed on the platen. Become.

As described above, in addition to driving the roller device using two drive motors, in the present invention, as shown in FIG. 3, one drive motor and a gear device are used, and a platen is used. Means for changing the driving speed of the roller can be used. The roller driving device 20 shown in FIG. 3 drives the driving roller 16 of the introduction-side roller 15 and the driving roller 18 of the discharge-side roller 17 in association with each other by a driving motor 19.
The drive mechanism is provided so as to drive the platen roller 13 via. The roller driving device 2
In the case of 0, the belt 22 is disposed between the pulley 21 of the driving motor 19 and the pulleys 23 and 24 of the two driving rollers 16 and 18, and the roller devices are driven in association with each other.

At the end of the shaft of the driving roller 18, two gears 25 and 26 are provided.
The gears provided on the shaft 30 mesh with each other to transmit the driving force.
, A pulley 38 of the platen roller 13 is driven via a belt 37 from a pulley 35 provided for the platen roller 13. The intermediate shaft 30 is provided with two gears 31 and 32, the small gear 31 is provided with an electromagnetic clutch 34, and the large gear 3
2 is provided on the shaft 30 via a one-way clutch 33. The two gears provided on the two shafts mesh with each other to transmit the driving force.
The driving of the small gear 31 is controlled by the electromagnetic clutch 34, and the driving of the large gear 32 is controlled by the one-way clutch 33.

That is, in the roller driving device 20 shown in FIG. 3, when the electromagnetic clutch 34 is turned on, the driving force is transmitted at the meshing portion between the large gear 25 and the small gear 31, and the shaft 30 is driven at a high speed. , But the large gear 32 idles via the one-way clutch 33.
When the electromagnetic clutch 34 is turned off, the small gear 31 becomes free, so that the small gear 26 and the large gear 32
The driving force is transmitted by the meshing with the shaft 30, and the shaft 30 is driven at a low speed. Therefore, the platen roller 1
When the image forming apparatus is configured by arranging the transport roller devices 15 and 17 on both sides of the document 3, the platen roller 13 is first driven at high speed, and the leading end of the document is nipped by the discharge roller. In this state, a device for driving the platen roller at a low speed can be constituted by the roller driving device 20 shown in FIG.

In the roller driving device shown in FIG.
The drive speed for the platen roller is controlled at the timing as shown in FIG. 2 so that when the document passes through the portion of the image scanning device, the platen roller is moved between the platen roller and the transport roller device disposed upstream and downstream thereof. Thus, the sheets can be conveyed in a state of being mutually pulled. When controlling the driving of the platen roller, the driving speed of the platen roller can be controlled only by turning on / off the electromagnetic clutch, so that the control means can be simplified. .

Further, as the platen roller and the driving roller provided in the image scanning apparatus of the present invention, a rubber roller having a rubber cylindrical member attached to a shaft member is used similarly to a roller device which has been generally used conventionally. It is also possible. However, with a conventional rubber roller such as chloroprene,
When a pressure-sensitive slip or the like is used as a document, oil such as diallyl methane SUS applied to the slip sheet swells the rubber, increasing the diameter of the roller and increasing the transport speed. was there. Therefore, in the present invention, the driving roller of the transport roller device is configured as the roller 40 shown in FIG.

The roller 40 is made of a material such as stainless steel or iron. The shaft member 42 and the roller body 41 are integrally formed, and a means such as spraying the same material on the surface of the roller body 41 is used. To form a rough surface, and to form a friction surface against the paper. Further, as the roller 40, the surface of the roller may be subjected to another roughening to form a friction surface. As described above, by forming the surface of the roller as a rough surface, the coefficient of friction with the document when the document is conveyed can be set to be large, and a feeding action similar to that of the rubber roller can be provided. Further, in the roller, even if oil such as diallylmethane SUS contained in the document adheres to the surface of the roller, the roller is not affected by the oil, and the function of feeding the document can be accurately exhibited. Can be.

In the transport roller device of the present invention, a roller as shown in FIG.
The pinch roller disposed opposite to the drive roller can be constituted by a roller using rubber having excellent oil resistance such as fluorine viton. As described above, by configuring the transport roller device by combining a metal drive roller and a pinch roller having excellent oil resistance, in the transport roller device of the present invention, a document coated with a special oil is used. When the image is scanned by using the oil, the transport performance of the transport roller device is not affected by the oil. Therefore, when the transport roller device is used, it is possible to accurately maintain the transport speed of the image scanning device with respect to the original, and the read image information is not disturbed.

An image reading apparatus using the roller driving device and the transport roller device configured as described above is shown in FIG.
Can be configured as a device as shown in FIG. In the image reading apparatus 1 shown in FIG.
The sheet feeder 3 is disposed to the document feeder 3, and the sheets are fed one by one by the feeder 3 toward the document feed path 4. In the document transport path 4, a number of transport roller devices 5 are arranged to transport the document toward the image scanning device 10, and the document scanned by the image scanning device 10 is discharged by a transport roller device 7 to a discharge tray. 8 to be discharged.
As shown in FIG. 1, the image scanning device 10 includes a platen 11, a reading device 12, and a platen roller 1.
In addition, an introduction-side roller 15 is disposed upstream of the platen 11 and a discharge-side roller 17 is disposed downstream of the platen 11, and the original is conveyed by these roller devices. Further, the document conveying path 4 of the image reading device 1
A sensor S1 for detecting double feed of originals and a sensor S2 for detecting paper size, inputting information from these sensors to the control device so that double feed of originals can be detected. ing.

In the image scanning apparatus 10, the driving means as shown in FIG. 1 or FIG. 3 is used to drive the platen roller at a high speed before the leading end of the document is nipped by the discharge roller 17. After the document is nipped by the discharge-side roller, a driving method for driving the platen roller at a low speed is used. As described above, by driving the roller device, a weak pulling action is applied to the document between the platen roller and the front and rear conveyance roller devices in a state where the conveyance speed for the document is regulated by the conveyance roller device. The scanning of the image can be performed in such a state that the document is not sagged or buckled.

In the image reading device 1,
The rollers used in the transport roller device can be configured using the roller members described with reference to FIG. By configuring the transport roller device using rollers having excellent oil resistance, without limiting the paper quality of the original,
An image scanning operation can be performed using an arbitrary document.

[0028]

According to the image reading apparatus of the present invention, the peripheral speed of the platen roller is relatively smaller than the peripheral speed of the first driving roller when the original is being conveyed. When the original is transported at a high speed, and the original is transported by the platen roller and the second drive roller on the downstream side, the peripheral speed of the platen roller is set to be relatively higher than the peripheral speed of the second drive roller. Since the document can be conveyed at a low speed, it is possible to prevent the document from sagging or buckling in the image reading unit.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an image scanning device according to the present invention.

FIG. 2 is a timing chart showing a document conveyance state in the apparatus of the present invention.

FIG. 3 is an explanatory view of another embodiment of the drive mechanism of the present invention.

FIG. 4 is a perspective view illustrating a configuration of a driving roller of the present invention.

FIG. 5 is an explanatory diagram of an image reading device to which the image scanning device can be applied.

FIG. 6 is an explanatory diagram illustrating a configuration of a conventional image scanning device.

[Explanation of symbols]

1 image reading device, 4 document feed path, 10
Image scanning device, 11 platen, 12 reading device, 13 platen roller, 14/20 roller drive device, 15 introduction roller, 17 discharge roller, 19 drive motor, 33 one-way clutch, 34 electromagnetic clutch.

Claims (1)

(57) [Claims] A platen disposed to correspond to a document reading position; a platen roller for conveying the document while pressing the document against the platen; and a platen roller disposed upstream of the platen roller for conveying the document. One drive roller, and a second drive roller disposed downstream of the platen roller and transporting the document, wherein the platen roller is configured to transport the document by the platen roller and the first drive roller. The document is transported with the peripheral speed of the roller relatively higher than the peripheral speed of the first drive roller, and the document is transported by the platen roller and the second drive roller. An image reading apparatus wherein the original is conveyed at a peripheral speed relatively lower than the peripheral speed of the second drive roller.