JPH04164733A - Image reading device - Google Patents

Abstract

PURPOSE:To read a satisfactory image at all times even it is a document of a carrier sheet by providing a means, which makes a link motion with a document position detecting means and stops the drive of a leading meas when a separate document reaches a reading position, and a means which transmitts the driving force as a pressure force of a separtion means. CONSTITUTION:When the front end of a document 2, which is separated and delivered, reaches a reading detection sensor 24, an electro-magnetic switch 6 actuates by a signal from the sensor 24 causing a clutch arm 7 to make a link motion and engage with a stopper portion of a spring clutch 5 which is then closed. Because the power to drive a leading roller 3 is not transmitted from a motor due to the closure of the clutch 5, the roller 3 stops at a normal position due to which the revolution of a backing plate 17 toward, the 'd' direction is not transmitted causing the only pressure on a separation piece 15 to be a weak elstic force of an elastic memvber 40. Thus after finkshing sepatation, the traveling load of the document 2, which starts to read, reduces and the reading blur, which is found when the rear end of a document passes through the separation area, is reduced by half.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image reading device that separates a plurality of originals stacked on a document table one by one and conveys them to image reading means.

2. Description of the Related Art Conventionally, this type of image reading apparatus has been constructed as shown in FIG. 3, for example.

In Fig. 3, 1 is a document table on which a transmission document is loaded, 2 is a transmission document loaded on document table 1, 2a is the lowest transmission document that is read first, and 2b is read after 2a. 3 is an introduction roller that guides the transmission document 2 at the paper feeding position; 4 is a shaft that becomes the rotation axis of the introduction roller 3; 6 is a spring clutch that controls the drive of the introduction roller 3; 6 is an electromagnetic switch that controls the operation of the spring clutch 6, and 7 is a clutch arm that makes the spring clutch 6 and the electromagnetic switch 6 interlock. Reference numeral 8 denotes an introduction aid that presses down from above and assists the introduction when the introduction roller 3 rotates and generally feeds the sending document 2. Reference numeral 9 denotes a shaft for rotatably attaching the introduction aid 8. Reference numeral 1o indicates that there is no original to be sent. In this state, a coil spring with one end fixed pulls the introduction aid 8 in the direction of arrow A so as to maintain a slight gap with the document table 1, and 11 is a first coil spring that detects whether the transmission document 2 is placed in the correct position. position detection sensor, 12 is the original platen 1
13 is a paper feed roller that feeds the transmission document 2; 14 is a clutch that is held by the paper feed roller 13 and rotates only in one direction; Reference numeral 15 denotes a separation piece for contacting and separating the sending original 2 introduced into the paper feed roller 13 with a pressing force sufficient to convey the sending original 2, and 16 a shaft to which the separating piece 15 is rotatably attached. , 17 is a support stand that holds the separation piece 16, 17a is a locking member that locks the separation piece 16 to the support stand 17, and 17b is a back surface of the support stand 17 which receives the force of a separation piece pressing tool to be described later. In addition, 18 is a paper feed roller 13
19 is a shaft to which the pressing tool 18 is rotatably attached, and 2o is a spring made of stainless steel wire or the like stretched in a straight line with both ends fixed, which springs the pressing tool 18 in the direction of arrow B. A member 21 is a feed roller 22 that conveys the lowermost transmission document 2a separated by the separation piece 16.
2 is a feed pinch roller that presses against the feed roller 21 and conveys the sending original 2a together with the feeding roller 21; 23 is a shaft that rotatably attaches the sending pinch roller 22; and 24 is a shaft that detects when the sending original 2a reaches the reading start position. A second position detection sensor 26 indicates the transmission document 2 to be read.
A guide plate 26 serves as a conveyance path for the transmission document 2a, 26 is a glass plate in which a part of the guide plate 25 is cut out and fitted therein, and 27 is a light source for reading the image of the transmission document 2a. 28 is a mirror of the first optical system that receives the reflected light from the transmission document 2a obtained through the glass plate 26; 29 is a mirror of the second optical system that further reflects the light reflected by the first mirror 28; , 3o is a lens that collects the reflected light from the mirror 29, 31 is a reading element that reads the light collected by the lens 30, 32 is an ejection roller that ejects the transmission document 2a after reading, and 33 is an ejection roller 32. A discharge pinch roller 34 presses the discharge document 2a and discharges the transmission document 2a together with the discharge roller 32.
36 is the shaft 23 of the feed pinch roller and the shaft 34 of the discharge pinch roller.
It is a board that is pressed from directly above.

FIG. 4 is a perspective view of the main parts of a conventional image reading device that reads a document by sandwiching it between carrier sheets.

In FIG. 4, reference numeral 36 denotes a carry sheet that allows feeding by sandwiching the original between transparent sheets when the original to be read is extremely thin and feeding is difficult.

In the conventional image reading device configured as described above, when the transmission document 2 is loaded on the document table 1 and fed, the separation piece 16 presses the paper feed roller 13 with the elastic force of the elastic material 20. Then, the transmission original 2a to be read for condylar level is separated from the lowest layer of the stacked transmission originals 2. And the separated transmission document 2
A is passed over a glass plate 26 for image reading by a feed pinch roller 21, and is ejected by an ejection pinch roller 32 after the image has been read.

Problems to be Solved by the Invention In conventional image reading apparatuses, during the warm-up period when the rear end of the transmitted document 2a pulls out the contact portion between the separation piece 16 and the paper feed roller 13, the transmission document 2a is The resistance due to the frictional force acting between the upper surface and the separation piece 16 disappears, and the feeding speed of the transmitted document 2a changes, causing uneven reading in the sub-scanning direction. Further, as shown in FIG. 4, when the carrier sheet 36 is used to read the transmission document 2, the carrier sheet 36 that has passed the feed roller 21 and the feed pinch roller 22 becomes a crescent shape with an upward curvature, and the lower surface of the carrier sheet There is a problem in that the transmission document 2a, which is sandwiched between the carrier sheet 36a and the upper surface 36b of the carrier sheet, cannot be maintained in its proper position on the glass plate 26, resulting in a distorted read image.

The above problem arises for the following reasons. That is, firstly, the force with which the separation piece 16 presses the paper feed roller 13 is constantly applied to the paper feed roller 13. In the meantime, the resistance due to the frictional force that had been acting between the upper surface of the sending document 2a and the separating piece 16 disappears, and the feeding speed of the document 2a changes.
This causes uneven reading in the sub-scanning direction. Second
When the transmission document 2a is sandwiched between the carrier sheet 36 and fed, the upper surface 36b of the carrier sheet is in contact with the separation piece 15 and the feed pinch roller 22. Here, since the pinch roller 22 has no driving force, no force acts on the upper surface 36b of the carrier sheet in the sub-scanning direction. However, since a predetermined frictional force is acting between the separation piece 15 and the upper surface 36b of the carrier sheet, the upper surface 36b of the carrier sheet
There is a force that tries to pull it back. On the other hand, the lower surface 36a of the carrier sheet is sent out in the conveyance direction by the paper feed roller 13 and the feed roller 21. As a result, carrier sheet 36
The transmission document 2a is sandwiched in a crescent shape with an upward curve, and the transmission document 2a sandwiched therein causes image disturbance.

The present invention has been tried in view of the above-mentioned problems, and it is an object of the present invention to provide an image reading device that can always read good images not only from ordinary originals but also from originals using carrier sheets.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides an introduction means for sequentially introducing originals stacked on a document table, and a paper feed roller that conveys the originals introduced by the introduction means to a reading position. , a separation means that comes into contact with the paper feed roller with a variable pressing force and separates the fed document, a document position detection means that detects when the separated document reaches a reading position, and the document position detection means. a driving stop means that interlocks with each other and stops the drive of the introduction means when the separated document reaches a reading position, and a transmission means that transmits the driving force of the introduction means as a pressing force of the separation means, When separating, the driving force is transmitted to the separating piece by the above-mentioned transmission means, so this force and the pressing force originally applied to the separating piece by the elastic material are combined, and as a result, the separating piece is loaded. The paper feed roller is pressed with enough pressure to pull out the bottom layer of the document, and it is introduced when it is confirmed that the extracted document has reached the reading area by a signal from the reading point detection means. This device is configured to stop the driving of the means, thereby reducing the separation pressure applied to the separation piece.

According to the above-described structure, the separating piece presses the paper feeding means with the pressure necessary for separation when separating the lowest sheet from a plurality of stacked originals, and the paper is separated after the separation is completed. When reading a document that has been read, the pressure with which the separation piece presses against the paper feeding means decreases, so the frictional resistance that acts between the top surface of the document and the separation piece decreases, and this causes the trailing edge of the document to be read to separate. During the warm-up period when the contact area between the sheet and the paper feeding means is removed, the frictional resistance that was previously acting between the upper surface of the document and the separating sheet decreases, and the feeding speed of the document being read decreases. It is possible to stably reduce reading unevenness in the sub-scanning direction.

Furthermore, when a document is sandwiched between the carrier sheet and read, the frictional resistance acting on the top surface of the carrier notebook is reduced, which reduces the lifting of the carrier sheet in the reading area, making it possible to obtain stable image quality.

Embodiment FIG. 1 is a sectional view showing a schematic configuration of an image reading apparatus in an embodiment of the present invention. In FIG. 1, the same components as in the conventional example are given the same numbers.

In FIG. 1, 37 is a pulley attached to the shaft 16, 38 is a pulley attached to the shaft 4 of the introduction roller 3, 39 is a timing bell that transmits the drive of the pulley 38 to the pulley 37), Reference numeral 40 denotes an elastic member having a weaker elastic force than the conventional elastic member 20.

FIG. 2 is a perspective view of a separator whose pressing force can be controlled, which is a feature of the present invention, and its surroundings.

In FIG. 2, 41 is a friction plate that causes sliding between the gift 16 and the separation piece 16, 42 is a compression spring arranged to sandwich the friction plate 41 from the outside, and 43 is a compression spring 42 from the outside. A fixture 44 is a bolt for fixing the fixture 43 to the shaft 16 at the compressed position. Both ends of the compression spring 420 have a protruding shape, and are provided with a friction plate 41 and a fixture 4, respectively.
3, and when the shaft 16 rotates, the friction plate 41 also rotates in the same direction. Furthermore, when the shaft 16 rotates, the support stand 17 is rotatably attached to the shaft 16 itself, but since the compression spring 42 presses against the friction plate 41 that rotates in conjunction with the shaft 16, friction with the support stand 17 occurs. Board 41
A rotational force is obtained in the direction of arrow d due to the frictional force acting between the two.

The operation of the image reading apparatus of this embodiment configured as described above will be described below.

When a document is loaded on the document table 1 and the apparatus starts operating, the electromagnetic switch 6 is activated, and in conjunction with this, the clutch arm 7 partially releases the stopper of the spring clutch 6. Then, power from a motor (not shown) is transmitted to the shaft 4, the introduction roller 3 rotates, and the document 2 is conveyed to the separation area C shown in FIG. At this time, the rotation of the introduction roller 3 is simultaneously transmitted to the pulley 3B, the timing belt 39, the pulley 37, and the shaft 16 in this order. This rotational movement of the shaft 160 rotates the support base 17 in the direction of arrow d while causing slippage on the friction plate 41 due to the above-described configuration.

Furthermore, the separation piece 16 presses the paper feed roller 13 due to the rotation of the support base 17 . Here, the separation piece 16 is always connected to the elastic member 4
0 presses the paper feed roller 13 with its weak elastic force.

Therefore, the resultant force of the above-mentioned force of the support base 17 pressing the separation piece 16 and the force of the weak elastic force of the elastic member 4o constantly pressing the separation piece 16 causes the conventional elastic member 20 to press the separation piece 16. By setting the rotational moment pressure to the support stand 17 so as to be equal to the force applied to the document 2, the separation pressure necessary to separate the bottom layer of the document 2 when it reaches the separation area C can be obtained. I can do it.

When the leading edge of the separated and fed document 2 reaches the reading point detection sensor 24, the electromagnetic switch 6 is operated in response to a signal from the reading point detection sensor 24, and the clutch arm 7 is interlocked to close the stopper of the spring clutch 6. to close the spring clutch 6. Due to this closure, the force with which a motor (not shown) drives the introduction roller 3 is not transmitted, and thereby the introduction roller 3 is stopped at a fixed position. Further, since the rotation of the introduction roller 3 is stopped, the rotational movement of the support base 17 in the direction of arrow d is not transmitted, and the pressing force applied to the separation piece 16 is only the weak elastic force of the elastic member 40. Therefore, the load on feeding the document 2a, which starts reading after separation is completed, is reduced, and uneven reading when the trailing edge of the document passes through the separation area C is halved.

When the rear end of the document 2a passes the reading point detection sensor 24, the electromagnetic switch 6 is operated in response to a signal from the reading point detection sensor 24, and the clutch arm 7 is interlocked to engage the stopper portion of the spring clutch 6. The spring clutch 6 is released and resumes rotation. This rotation feeds the remaining originals 1b stacked on the original platen 1, and the above-described series of operations are repeated until there are no more stacked originals left.

As described above, according to this embodiment, the necessary separation pressure is obtained only when the original is separated in the separation area C, and when the separated original is read, the separation pressure is applied only by the elastic member 40, so that the original can be moved. Stability can be increased.

Furthermore, even when a carrier sheet is used, during the reading operation, the running load applied to the upper surface of the carrier sheet is reduced by the pressing force of the separating piece 16, which reduces the lifting of the carrier sheet at the reading position, and the position of the sandwiched document is reduced. Effects of the invention that can obtain stable and high-quality read images As is clear from the above description, the present invention provides an introducing means for sequentially introducing originals stacked on a document table, and an introduction means that is introduced by this introducing means. A paper feed roller that conveys the document to the reading position, a separating means that comes into variable pressure contact with the paper feed roller and separates the fed document, and a document position that detects when the separated document reaches the reading position. a detection means, a drive stop means that is linked to the document position detection means and stops driving the introduction means when the separated document reaches a reading position, and a driving force of the introduction means is used as a pressing force of the separation means. By providing a transmission means for transmitting the document, when separating the lowest sheet from a plurality of stacked originals, the separation piece presses the paper feeding means with the pressure necessary for separation, and after the separation is completed, the paper is separated. When reading a separated original, the pressure with which the separation piece presses against the paper feeding means is reduced, which reduces the feeding load when reading the original, and also reduces uneven running when the original leaves the separation area. That is, reading unevenness in the sub-scanning direction is reduced and high-quality images can be obtained.

Furthermore, even when a carrier sheet is used for a document, the present invention reduces the load acting on the top surface of the carrier sheet, thereby reducing the lifting of the carrier sheet at the reading point, resulting in extremely stable image quality. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is a central cross-sectional view showing a schematic configuration of an image reading device according to an embodiment of the present invention, FIG. 2 is a perspective view of the main parts of the image reading device, and FIG. 3 is a schematic cross-sectional view of a conventional image reading device. 4 are schematic cross-sectional views when a document is fed between carrier sheets in a conventional image reading device. 2...Stacked originals, 2a...Original in the lowest layer of the originals 2, 2b...Original in the second from the bottom layer among the originals 2, 3...Introduction roller, 5...・Spring clutch, 6... Electromagnetic switch, 7... Clutch arm, 13... Paper feed roller, 16... Separation piece, 1
7... Friction plate, 24... Original reading position detection sensor, 37... Pulley, 38... Pulley, 39... Timing belt, 4°... Resilient member, 41... Friction plate , 42... compression spring, 43... fixture.

Claims (1)

[Claims] An introduction device that sequentially introduces documents stacked on a document table; a paper feed roller that conveys the documents introduced by the introduction device to a reading position; and a document that is fed in variable pressing force contact with the paper feed roller. document position detection means for detecting when the separated document reaches the reading position;
a drive stop means that operates in conjunction with the document position detection means and stops driving the introduction means when the separated document reaches the reading position; and a transmission means that transmits the driving force of the introduction means as a pressing force of the separation means. An image reading device comprising: