Image reading apparatus and image formation apparatus

An image reading apparatus has a reading portion configured to read the image of the original at the reading position located on a supporting surface for supporting the original, an original feeding portion configured to convey an original to the reading position, a movable guide portion which faces the supporting surface and guides the original conveyed by the original conveying portion to the reading position, and a biasing member configured to apply a biasing force to the guide portion toward the supporting surface, wherein the movable guide portion has a rib portion, the rib portion projects toward the supporting surface and is formed along the original conveying direction, and the rib portion presses an original, that is read by the reading portion while the original is conveyed by the conveying portion, to the supporting surface by the biasing force of the biasing member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image reading apparatus for reading information of conveyed original and an image formation apparatus using the same.

2. Description of the Related Art

In a case where an image is read by means of an image reading apparatus, an original of the image has to be in intimate contact with a platen glass at a reading position. For this reason, as shown inFIG. 12, a conventional image reading apparatus has a reading white plate101for allowing an original S to be in intimate contact with a platen glass100at the reading position.

It has been proposed that in order to securely prevent the original from floating at the reading position, a flexible sheet member102is provided upstream of the original reading position in the conveying direction to prevent image reading disturbance so that reading accuracy is improved (Patent document 1: Japanese Patent Application Laid-Open No. 2003-051915).

However, in the case of the above-described structure, since the original is pressed by means of the sheet member102, the contact surface between the sheet member and the original becomes large. Thus, friction noise produced by the sheet member and the original is likely to be considerable. In a case where pressing force of the original is to be increased in order to improve the reading accuracy, when the number of the sheet member102is increased in the original width direction or the width of the sheet member102is increased, the friction noise is further likely to be bigger.

In the case of the above-described structure, since the sheet member102constantly presses the original, at the moment the rear end of the original passes over the sheet member102, the load applied to the original is released, so that sometimes load fluctuation occurs. Due to the occurrence of the load fluctuation, reading accuracy of the original image may be deteriorated, or the original may flap to generate noise.

SUMMARY OF THE INVENTION

The present invention has been developed, considering the above-described conditions, and provides an image reading apparatus and an image formation apparatus in which image reading accuracy is excellent while noise from the conveyed original is reduced.

An image reading apparatus of the present invention for solving the problem mentioned above is an image reading apparatus having the following. It has a reading portion configured to read the image of the original at the reading position located on a supporting surface for supporting the original, an original feeding portion configured to convey an original to the reading position, a movable guide portion which faces the supporting surface and guides the original conveyed by the original conveying portion to the reading position, and a biasing member configured to apply a biasing force to the guide portion toward the supporting surface, wherein the movable guide portion has a rib portion, the rib portion projects toward the supporting surface and is formed along the original conveying direction, and the rib portion presses an original, that is read by the reading portion while the original is conveyed by the conveying portion, to the supporting surface by the biasing force of the biasing member.

Further, an image reading apparatus of the present invention is an image reading apparatus having the following. It has a reading portion configured to read the image of the original at the reading position located on a supporting surface for supporting the original, an original feeding portion configured to convey an original to the reading position, a guide portion which face to the supporting surface and guides the original conveyed by the original conveying portion to the reading position, and a movement portion which moves the pressing member between a pressing position for pressing an original to the supporting surface and a separation position which is separated more than the pressing position from the supporting surface.

The present invention provides an apparatus in which noise from an original which is conveyed can be reduced and in which reading accuracy is excellent.

DESCRIPTION OF THE EMBODIMENTS

Next, an image reading apparatus according to one embodiment of the present invention is described illustrating an image formation apparatus having the image reading apparatus.

First Embodiment

FIGS. 1 through 7show an image reading apparatus and an image formation apparatus according to a first embodiment, andFIGS. 1 through 3are exemplary views showing the feature of the image reading apparatus according to the first embodiment. Further,FIG. 4is a schematic entire explanatory view of the image formation apparatus having the image reading apparatus, andFIGS. 5 through 7are explanatory views showing the entire structure of the image reading apparatus.

First, an image formation apparatus will be described with reference toFIG. 4. An image formation apparatus A of the present embodiment has an image reading apparatus B on an upper portion of an apparatus main body100, and a copy machine forming an image on a sheet by an electronic picture image formation method as an image formation method is exemplified.

Sheet cassettes101are mounted on a lower portion of the apparatus main body100. A sheet conveying path is formed from this sheet cassette101to an image formation portion, and feeding rollers102, pairs of separation rollers103, pairs of conveying rollers104are arranged. At the time of image formation, sheets accommodated in this sheet cassette101are conveyed by means of the feeding roller102, and are separated by means of the pair of separation rollers103one by one, to be conveyed to the image formation portion by means of the pairs of conveying rollers104.

A toner image is formed on a photosensitive drum member105which constructs the image formation portion in synchronization with the sheet conveying. For that purpose, image formation process means such as an exposure device106and a development device107are arranged adjacent to the photosensitive drum member105. At the time of image formation, light in response to original information read by the image reading apparatus B is illuminated from the exposure device106to the photosensitive drum member105to form a static image, and toner is developed for this static image by means of the development device107, so that obtained toner image is transferred to the conveyed sheet.

The sheet on which the toner image is transferred is conveyed to a fixing device108, is heated and pressed to fix the toner image. Thereafter, the sheet is discharged to the outside of the apparatus by means of pairs of discharge rollers109.

Next, an image reading apparatus will be described with reference toFIGS. 5 through 7.FIG. 5is an explanatory perspective view of the image reading apparatus, viewed from an upper side, andFIG. 6is an explanatory perspective view viewed from an upper side in a state where a pressing plate unit of the image reading apparatus is opened.FIG. 7is a principal explanatory cross-sectional view illustrating the image reading apparatus.

As shown inFIGS. 5 and 6, a white plate2is disposed on a static image reading portion located on the lower surface of a pressing plate unit1so that an original D2is in intimate contact with a platen glass6which is a transparent member when a static image original is read, thereby to construct a structure in which the pressing plate unit1can be opened and closed about a hinge3.

As shown inFIG. 7, a conveyed original reading part5has an original conveying path (hereinafter referred to as “U-turn path”) of a roughly U-shaped form. An original stopper10regulating the front end position of an original D1which is stacked on an original tray4is disposed on the U-turn path7. Members for conveying the original D1include a pick-up roller17which abuts an uppermost one of the originals D1stacked on the original tray4to pick this up and a separation roller8and a separation pad9which separate and feed the originals D1one by one. Further, original conveying members include a conveying roller13being an auto original feeding portion that conveys a fed original to a reading position and a pair of discharge rollers14being an original discharge portion which conveys an original which has passed the reading position. On the original conveying path, as sensors detecting the original, an original existence detecting sensor11detecting the existence of the original D1on the original tray4and an original edge sensor15detecting a front end portion and a rear end portion of the original to be conveyed are attached.

On a lower portion of the reading position on the original conveying path, an intimate type image sensor16being a reading portion which reads the original located on the reading position is disposed. This intimate type image sensor16illuminates light from an LED array being a light source to an image information surface of the original D1, and allows reflected light reflected at the image information surface to be focused on the sensor element through a lens to read the image information.

At the conveyed original reading part5, when an operator puts the original D1on the original tray4, the reading image surface of the original D1is on the upper side thereof so that the original D1can be set from the apparatus' operator side. At this time, the front end position of the original D1is regulated by the original stopper10, and by means of the original existence detecting sensor11the existence of the original D1is detected.

A control section777controls the respective portions of the conveyed original reading part5. Signals from the original existence detecting sensor11and the original edge sensor15are input to the control section777. Signals from an operation section (not shown) are input to the control section777. The control section777controls operations of motors that drive the pick-up roller17, the separation roller8, the conveying roller13, and the pair of discharge rollers14, thereby to control the conveyance of an original.

When start of reading is directed by an operator through the operation section (not shown), a drive portion (not shown) rotates. Thus, the original stopper10is pushed down, and the original D1is conveyed to a separation portion between the separation roller8and the separation pad9by means of the pick-up roller17. The originals D1are separated one by one, so that an uppermost original D1is separated and conveyed. The separated original D1is conveyed along the U-turn path7by means of the conveying roller13, and is further conveyed to the reading portion of the intimate type image sensor16.

In the auto original feeding portion, after the front end portion of the original D1is detected by means of the original edge sensor15, reading of the image information by means of the intimate type image sensor16is started when it is conveyed a predetermined distance from that position. After the start of reading, the original goes to the pair of discharge rollers14. After the rear end portion of the original D1is detected by the original edge sensor15, when it is conveyed a predetermined distance from that position, reading of the image information by means of the intimate type image sensor16is completed. This original D1is discharged to the outside of the apparatus by means of the pair of discharge rollers14.

In this way, in the conveyed original reading part5, the above-described reading operation is repeated until the original existence detecting sensor11detects a nonexistence of an original.

In the present embodiment, a pressing guide member18(a movable guide portion) disposed upstream of the reading position in the original conveying direction and a reading white plate20(second guide portion) for guiding the original at the reading position are provided in order to prevent an original from floating at the reading position at the time of reading the original. Next, a structure for that purpose will be described with reference toFIGS. 1 through 3.FIG. 1is an enlarged view of a conveyed original reading part, andFIG. 2is an explanatory view in which the reading white plate is viewed from the original conveying direction.FIG. 3is an explanatory perspective view illustrating ambient structures of the original pressing member.

[Original Guide At Reading Position]

As shown inFIG. 1, a transparent contact glass12being a supporting member supporting an original located at a reading position Y is disposed on an upper portion of the intimate type image sensor16, and a conveyed original is in intimate contact with a supporting surface12aof the contact glass12to be read. For that purpose, a reading white plate20being a second guide portion for holding the original located at the reading position Y on the contact glass12is arranged. This reading white plate20is swingably attached to a lower guide member21, and a force is applied to the member in the contact glass12direction by means of biasing springs25. The reading white plate20being a guide member that guides an original at the reading position Y guides the original such that the original is pressed against the contact glass12.

As shown inFIG. 2, the reading white plate20has abutting portions20a,20babutting the contact glass12in the both ends thereof in the original width direction perpendicular to the original conveying direction and a separation portion20cfloating approximately 0.3 to 0.5 mm from the contact glass12. The abutting portions20a,20bare disposed outside of the conveying area. That is, the abutting portions20a,20bare arranged apart from the conveying area in which the original is conveyed, in the width direction. The original passes through a lower portion of the separation portion20c, so that it does not press the contact glass12. Thus, it can be reduced that stain such as glue adhering to the original adheres to the contact glass12, thereby improving reading of an image.

A force is applied to the reading white plate20toward the contact glass12by the biasing springs25as described above. However, since the reading white plate20of the present embodiment is a mold member, when a force is applied to the central portion of the reading white plate20by the biasing springs25, the central portion is flexed to come in contact with the contact glass12. Thus, in the present embodiment, the biasing springs25are arranged so as to apply a force to the both end portions of the reading white plate20. Thus, the separation portion20cprevents the conveyed original from floating without pressing the original, so that any object adhering to the original does not adhere to the contact glass12.

As shown inFIG. 1, in the present embodiment, a pressing guide member18for pressing an original to the contact glass12is provided between the conveying roller13and the reading white plate20on the conveying path of an original. The pressing guide member18guided the original to the reading position and presses the original to the contact glass12. This pressing guide member18is to prevent a large image drift due to flapping of an original at the original reading position Y when the original front end goes to a downstream side guide member24and the pair of discharge rollers14arranged downstream of the contact glass12.

The pressing guide member18is movably supported by the lower guide member21. The pressing guide member18is a mold member. Specifically, as shown inFIG. 3, a boss fitting portion18cof the pressing guide member18is rotatably attached to a boss portion21aof the lower guide member21, and an A part facing them also has a similar structure. Thus, the pressing guide member18is pivotally supported on the lower guide member21. A force is applied to the pressing guide member18toward the contact glass12by means of a biasing spring22being a biasing means.

As shown inFIG. 3, the pressing guide member18has, on a plurality of portions thereof in the original width direction, rib portions18d,18eprotruding toward the contact glass12. These rib portions18d,18eare formed along the original conveying direction. These rib portions18d,18ehave a flexed shape so as to guide an original to the contact glass12, and are constructed such that the rib portions18d,18eabut the contact glass12and that other portions do not abut it. In addition the shape along the original conveying direction of the rib portions18d,18ehere includes a rib portion that in a state inclining to the original conveying direction not parallel to the original conveying direction.

The original conveyed by means of the conveying roller13is guided to the contact glass12by the pressing guide member18, and is pressed to the contact glass12by the rib portions18d,18e. Thus, even if an original is thick, it does not float from the contact glass12to prevent the original from flapping, and image drift at the reading position Y can be reduced. Since the contact area between the rib portions18d,18eand the original is small, the friction noise produced by the rib portions and the original is reduced.

Thus, flapping of the original is prevented without increasing the biasing force of the reading white plate20and the pressing guide member18, and reduction of friction noise is realized. In the above mentioned explanation, the pressing guide member18presses the original to the contact glass12by the biasing force of the biasing spring22. But it can be formed that the pressing guide member18presses the original to the contact glass12by the weight of the pressing guide member18without a spring.

Second Embodiment

Next, an apparatus according to a second embodiment will be described with reference toFIGS. 8 through 11. Since the basic structure of the apparatus of the present embodiment is the same as that of the above-described embodiment, redundant explanation will be omitted, and here, a structure featuring the present embodiment will be described. The same reference numerals refer to members having the same functions as those of the above-described embodiment.

The present embodiment differs from the above-described embodiment in that the pressing guide member18and the contact glass12are constructed such that they can abut each other and that the pressing guide member18can be separated from the contact glass12, in accordance with the original conveying condition.

For that purpose, as shown inFIGS. 8 and 9, a movement portion is provided for allowing the pressing guide member18which a force is applied thereto by the biasing spring22and abuts the contact glass12to move for separating the pressing guide member18and the contact glass12.FIG. 8is an explanatory perspective view of a pressing member according to the second embodiment, andFIG. 9is an explanatory cross-sectional view of an image reading portion according to the second embodiment.

As shown inFIGS. 8 and 9, the pressing guide member18has swing regulating portions18a,18b, and their flexed distal ends engage the lower guide member21. High molecular weight actuators19,23being the movement portions are attached between the flexed ends of the swing regulating portions18a,18band the lower guide member21. These high molecular weight actuators19,23have a characteristic that it expands and contracts by applying a voltage, and the present embodiment adopts ones having a characteristic of expanding and contracting when a positive voltage and a negative voltage are applied, respectively. The actuators may be formed of a compound body of a high molecular weight body and metal. A voltage applied to the high molecular weight actuator is controlled by the control section777.

FIGS. 8 and 9show a state in which the high molecular weight actuators19,23are contracted. In this state, a force is applied to the pressing guide member18by the bias spring22, and the rib portions18d,18eare at pressing positions where they can abut the contact glass12.

FIG. 10is an explanatory perspective view illustrating a state wherein the high molecular weight actuators19,23are expanded, andFIG. 11is an explanatory cross-sectional view of that state. As shown in the drawings, when a positive voltage is applied to the high molecular weight actuators19,23, the high molecular weight actuators19,23are expanded. Thus, the swing regulating portions18a,18bare pulled upwards, and the rib portions18d,18eare positioned at separation positions where they are separated from the contact glass12. Here, expanding force of the high molecular weight actuators19,23have been greater than the biasing force of the biasing spring22, and the high molecular weight actuators19,23allow the swing regulating portions18a,18bto move to separation positions against the biasing force of the biasing spring22.

As described above, in the structure in which the pressing guide member18can abut the contact glass12and can be separated from it, in the present embodiment, first, until the conveyed original front end reaches the pair of discharge rollers14, a negative voltage is applied to the high molecular weight actuators19,23. That is, when a signal to start reading is input from the operation section to the control section777, the control section777applies a negative voltage to the high molecular weight actuators19,23. Thus, as shown inFIGS. 8 and 9, the high molecular weight actuators19,23are contracted so that the rib portions18d,18eabut the contact glass12to allow the conveyed original to be pressed to the contact glass12by the biasing force of the biasing spring22. Therefore, the original is prevented from flapping at the original reading position Y of when the original front end enters the downstream side guide member24and the discharge rollers14.

After the conveyed original front end reaches the pair of discharge rollers14, until the rear end of the original passes the conveying roller13, a positive voltage is applied to the high molecular weight actuators19,23. That is, the control section777performs control such that a positive voltage is applied to the high molecular weight actuators19,23before the rear end of the original passes the conveying roller13in response to the signal from the original edge sensor15. In this way, as shown inFIGS. 10 and 11, the high molecular weight actuators19,23are expanded so that the rib portions18d,18eare separated from the contact glass12. Thus, the original is prevented from flapping due to load fluctuation applied to the original of when the conveyed original rear end passes the pressing guide member18.

The control section777performs control such that a negative voltage is again applied again to the high molecular weight actuators19,23after the rear end of the original passes the pressing guide member18in response to the signal from the original edge sensor15. This is to prepare conveyance for pressing the original which is to be conveyed next.

The control of the control section777will be described with reference to the flow chart ofFIG. 13.

First, the control section777determines whether the signal for beginning to read is input from the operation section (S1). If the signal for beginning to read is input, the control section777performs control such that a negative voltage is applied to the high molecular weight actuators19,23(S2). By this, the pressing guide member18is located at the pressing position.

Thereafter, the control section determines whether the original edge sensor15has detected the conveyed original (S3). The control section777determines whether a predetermined time T1has elapsed after the original edge sensor15detected the original (S4). This predetermined time T1is set so as to be after reaching of the original front end to the pair of discharge rollers14and before passing of the original rear end through the conveying roller13.

After the predetermined time T1elapsed, the control section777performs control such that a positive voltage is applied to the high molecular weight actuators19,23(S5). By the applying of the positive voltage to the high molecular weight actuators19,23, the pressing guide member18is located at the separation position.

Thereafter, the control section777determines whether a second predetermined time T2has further elapsed (S6). The second predetermined time T2is set so as to be after passing of the original rear end through the pressing guide member18. Then, the control section777determines whether a next original exists or not (S7), and the process returns to S2in the case where the next original exists. In the case where the next original does not exist, applying the voltage to the high molecular weight actuators is ended (S7), to finish the process.

When the pressing guide member18is located at the separation position, since the conveyed original is supported by the conveying roller13and the pair of discharge rollers14, a stable conveying condition is obtained. Thus, even when the pressing guide member18is separated from the contact glass12, original reading accuracy is rarely influenced.

In the present embodiment, the original is prevented from flapping as described above, and the load fluctuation of when the original rear end passes through the conveying roller13is prevented, thereby enabling the realization of the image reading apparatus in which image disturbance does not exist over the entire area where an image is read.

A feature in which the pressing guide member18is moved by the high molecular weight actuators19,23has been exemplified. However, a moving portion to allow the pressing guide member18to move is not limited to the high molecular weight actuator. For example, a solenoid may be employed to move the pressing guide member18.

This application claims the benefit of Japanese Patent Application No. 2007-090561, filed Mar. 30, 2007, which is hereby incorporated by reference herein in its entirety.