DOCUMENT CONVEYING DEVICE AND IMAGE FORMING APPARATUS

A document conveying device includes an inversion path, a lift member, a drive source, a conveying part, a detection part and a control part. The lift member forms an upper side face of the inversion path. The drive source moves the lift member upward and downward in the inversion path. The conveying part is pushed up by the uppermost document, and rotates to feed the uppermost document. The detection part detects a height of the conveying part. The control part executes an overload feeding mode in which whether the document is overloaded is determined based on a detection result of the detection part, when an overload is determined, the lift member is moved downward until the overload is not determined, the drive source moves the lift member upward until the conveying part is pushed up to an optimum feeding height, and then the uppermost document is fed.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese Patent application No. 2017-134925 filed on Jul. 10, 2017, which is incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a document conveying device conveying a document and an image forming apparatus which forms an image based on an image data of the document conveyed by the document conveying device.

An image forming apparatus is sometimes provided with a document conveying device which feeds a document placed on a placement tray and conveys the document to an image reading part where an image data of the document is read. Based on the image data read by the image reading part, the image forming apparatus forms an image on a sheet.

The document is placed on the placement tray as described above. If the document is overloaded, the feeding and separating of the document may not be performed normally. Then, the document conveying device is sometimes configured to have a countermeasure against the overload of the document. For example, the document conveying device may stop the feeding of the document when the overload of the document is detected. Alternatively, the document conveying device may have a configuration where a home position of the placement means (the placement tray) is set to upper and lower positions and moves the placement means to the lower home position when the overload is detected.

However, if the feeding of the document is stopped when the overload of the document is detected, it is required to remove the document from the placement tray and then to replace the document on the placement tray after the number of the document is reduced. Then, the user spends much time for the replacement work, and the document conveying ability is lowered. In case of the two home positions, since two detecting means for detecting the home position are required, the control of the document conveying device is complicated.

SUMMARY

In accordance with an aspect of the present disclosure, a document conveying device includes an inversion path, a lift member, a drive source, a conveying part, a detection part and a control part. The inversion path inverts a conveying direction of a document. On the lift member, the document is placed. The lift member forms a part of an upper side face of the inversion path. The drive source moves the lift member upward and downward in the inversion path. The conveying part comes into contact with an uppermost document of the document placed on the lift member, is pushed up by the uppermost document, and rotates to feed the uppermost document. The detection part detects a height of the conveying part. The control part executes an overload feeding mode in which whether the document is overloaded or not is determined based on a detection result of the detection part, when an overload of the document is determined, the lift member is moved downward until the overload is not determined, the drive source is driven to move the lift member upward until the conveying part is pushed up to an optimum feeding height by the uppermost document, and then the uppermost document is fed.

In accordance with an aspect of the present disclosure, an image forming apparatus included an image forming part which forms an image based on an image data of a document conveyed by the document conveying device.

DETAILED DESCRIPTION

Hereinafter, with reference to the attached drawings, a document conveying device and an image forming apparatus according to one embodiment of the present disclosure will be described.

With reference toFIG. 1, an entire structure of a color printer1will be described.FIG. 1is a front view schematically showing the entire structure of the color printer1. In the following description, a near side (a front side) of a paper plan ofFIG. 1is decided to be a front side of the color printer1. In each figure, Fr, Rr, L and R respectively indicate a front side, a rear side, a left side and a right side of the color printer1.

As shown inFIG. 1, the color printer1includes an image forming apparatus3and a document conveying device5arranged above the image forming apparatus3. The document conveying device5is configured to convey a document along a conveying path automatically and to read an image data of the conveyed document. The image forming apparatus3includes an image forming part7which forms an image, corresponding to the image data read by the document conveying device5, on a sheet.

Next, with reference toFIG. 2toFIG. 4, in addition toFIG. 1, the document conveying device5will be described.FIG. 2is a sectional view showing a conveying unit,FIG. 3is a sectional view showing a lift member andFIG. 4is a block diagram of a control part. The document conveying device5is provided with a conveying unit11(refer toFIG. 1), a document reading unit13(refer toFIG. 1), a control part15(refer toFIG. 4) and an operation panel17(refer toFIG. 4). The conveying unit11conveys the document automatically along the conveying path. The document reading unit13is arranged below the conveying unit11, and reads the image date of the document. The control part15controls the document conveying operation of the conveying unit11and the image data reading operation of the document reading unit13. The operation panel17is an operation part operated by a user.

The document reading unit13will be described with reference toFIG. 1. The document reading unit13is formed in a shallow approximately rectangular parallelepiped shape capable of being placed on an upper face of the image forming apparatus3. An upper face of the document reading unit13is covered with a contact glass21. Under a left end portion of the contact glass21, a contact type image sensor23reading the image data of the document is arranged along a width direction (a front-and-rear direction) perpendicular to the conveying direction of the document.

The conveying unit11will be described with reference toFIG. 1andFIG. 2. The conveying unit11is provided with a placement tray25, a lift member27, a document conveying part29and an ejecting tray31which are arranged in the order along the conveying direction. They are supported by a main body33.

The placement tray25is a plate-like rectangular member on which a predetermined size document is placed. On an upper face of the placement tray25, a pair of side cursors are supported in a slidable manner in the width direction so as to align the document in the width direction. The placement tray25is supported by the main body33with an inclined posture downward along the conveying direction.

The lift member27is arranged at the downstream side of the placement tray25in the conveying direction so as to connect with the upper face of the placement tray25. On the lift member27, a downstream side end portion (a lead side end portion) of the document is placed. As shown inFIG. 3, the lift member27holds a document placement detection sensor37. The document placement detection sensor37detects whether the document is placed on the lift member27or not. The document placement detection sensor37is electrically connected to the control part15.

The lift member27is formed with a supporting shaft39at the end portion on the side of the placement tray25, and is supported so as to be turned together with the supporting shaft39. The supporting shaft39is supported by the main body33in a rotatable manner. To one end of the supporting shaft39, a motor41rotatable normally and inversely, as a drive source which moves the lift member27upward and downward, is connected. When the motor41rotates the supporting shaft39, the lift member27is turned in the upper-and-lower direction (moved upward and downward) around the supporting shaft39. The supporting shaft39is rotated by the motor41so as to position the lift member27at a home position. The motor41is electrically connected to the control part15.

As shown inFIG. 2, the document conveying part29includes a main conveying path43and an inversion conveying path45formed therein. The main conveying path43is formed in a laid down U-shaped curve from an inlet43aprovided at the downstream side of the lift member27to an outlet43bprovided below the inlet43a.The inlet43ais formed with a guide part47. As shown inFIG. 3, the guide part47includes an abutment wall47aslightly inclined to the downstream side with respect to the vertical face and a guide wall47binclined to the downstream side from an upper end of the abutment wall47a.On the abutment wall47a,the lead edge of the document placed on the placement tray25and the lift member27is butted. Then, an uppermost document of the placed document is fed along the guide wall47b.This regulates a number of the document to be fed suitably.

On the main conveying path43, a feeding part51, a document passing detection sensor53, a first conveying roller55, a resist roller57, an image reading part59, a second conveying roller61and a third conveying roller63are provided in the order along the conveying direction.

The feeding part51feeds the uppermost document of the document placed on the placement tray25and the lift member27to the main conveying path43. The feeding part51includes a feed roller67, a supply belt69, a separation roller71and a holder73. The feed roller67is a conveying part which comes into contact with the uppermost document and then feeds the uppermost document. The supply belt69and the separation roller71forms a separation nip at which the fed document is separated. The holder73supports the feed roller67and the supply belt69.

The feed roller67is supported by an upstream side end portion of the holder73in a rotatable manner. A rotating shaft67aof the feed roller67is connected to a motor75. When the rotating shaft67ais rotated by the motor75, the feed roller67rotates in the clockwise direction ofFIG. 2. The supply belt69is wound around an upstream side pulley77and a downstream side pulley79, at the downstream side of the feed roller67. When a rotating shaft79aof the downstream side pulley79is driven to be rotated, the supply belt69circulates in the clockwise direction ofFIG. 2. The holder73is arranged above the inlet43aof the main conveying path43, and the feed roller67faces a downstream side end portion of the lift member27with a predetermined space. The separation roller71comes into contact with the supply belt69from the lower side between the pulleys77and79. Between the separation roller71and the supply belt69, the separation nip is formed.

The holder73is supported in a turnable manner in the upper-and-lower direction around the rotating shaft79aof the downstream side pulley79. The upstream side end portion of the holder73is biased downward by a spring81such that the feed roller67is pressed on the uppermost document of the document placed on the placement tray25and the lift member27. On the other hand, when the feed roller67is pushed up by the document from the lower side, the holder73is turned upward around the rotating shaft79aagainst the biasing force of the spring81.

The height of the holder73is detected by an upper limit detection part85as a detection part which detects the feed roller67turned to an optimum feeding height. At the optimum feeding height, the feed roller67can feed the uppermost document of the document placed on the placement tray25and the lift member27suitably along the guide wall47bof the guide part47. When the document is fed and a number of the placed document is reduced, the holder73is turned as described above, and the height of the feed roller67is varied. That is, a contact position between the feed roller67and the uppermost document is varied. Then, it may be difficult to feed the uppermost document suitably along the guide wall47b.Therefore, by rotating the supporting shaft39of the lift member27until the upper limit detection part85detects the holder73, it becomes possible to keep the feed roller67at the optimum feeding height.

The upper limit detection part85includes a protruding piece87provided at the upstream side end portion of the holder73and an optical sensor89provided at the main body33. The optical sensor89includes a light emitting part and a light receiving part which face each other with a predetermined interval, and between the light emitting part and the light receiving part, a light path is formed. When the light path is closed, the optical sensor89is switched from off to on and then outputs a signal. The optical sensor89is positioned to the main body33such that the protruding piece87of the holder73turned to the optimum feeding height is inserted between the light emitting part and the light receiving part, that is, the protruding piece87closes the light path. The optical sensor89is electrically connected to the control part15.

The document passing detection sensor53detects whether the document passes through a predetermined position on the main conveying path43. The document passing detection sensor53is electrically connected to the control part15.

The image reading part59is arranged so as to face the contact type image sensor23of the document reading unit13via the contact glass21. The document is conveyed to the image reading part59after the conveying timing is controlled by the resist roller57, and the image data of the document is read by the contact type image sensor23.

The first conveying roller55is arranged between the document passing detection sensor53and the resist roller57. The second conveying roller61is arranged at the downstream side of the image reading part59. The third conveying roller63is arranged at the outlet43b.

Here, the main conveying path43contains a first conveying path43cfrom the inlet43ato the second conveying roller61and a second conveying path43dfrom the second conveying roller61to the outlet43b.

Next, the inversion conveying path45will be described. The inversion conveying path45contains a third conveying path45ainverting the conveying direction of the document and a fourth conveying path45bjoining the document to the main conveying path43after the conveying direction of the document is inverted. The third conveying path45ais branched upward from the second conveying path43dat the downstream side of the second conveying roller61, and extends below the lift member27and then to a portion above the outlet43bof the main conveying path43. That is, a lower face of the lift member27forms a part of an upper side face of the third conveying path45a.On the third conveying path45a,an inversion roller93inverting the conveying direction of the document is provided. The fourth conveying path45bis branched from the third conveying path45aat the upstream side of the inversion roller93and is joined to the main conveying path43between the document passing detection sensor53and the first conveying roller55.

As shown inFIG. 3, when the lift member27is turned to the home position, the third conveying path45ais formed below the lower face of the lift member27. On the other hand, when the lift member27is turned downward lower than the home position (refer to a two-dotted line inFIG. 3), the third conveying path45ais closed with the lift member27.

With reference toFIG. 1andFIG. 2, the ejecting tray31is formed below the placement tray25, and is inclined upward from a portion below the outlet43bof the main conveying path43toward the downstream side along the conveying direction.

Document conveying operations at a one-side reading and a both-side reading will be described with reference toFIG. 2. At the one-side reading, the document is conveyed along the main conveying path43, and ejected on the ejecting tray31after the image data of the document is read at the image reading part59. At the both-side reading, the document is conveyed along the first conveying path43c,and then along the third conveying path45aafter the image date of one face of the document is read at the image reading part59. Then, after the conveying direction of the document is inverted by the inversion roller93on the third conveying path45a,the document is conveyed along the fourth conveying path45band then first conveying path43c.At this time, the front side face and the back side of the document is inverted. Then, the document is conveyed along the first conveying path43c,and after the image data of the other face of the document is read at the image reading part59, the document is conveyed along the second conveying path43dand then ejected on the ejecting tray31.

Next, the control part15will be described with reference to a block diagram shown inFIG. 4. The control part15includes a document placement determination part101, a lift member drive part103, a roller height determination part105, a document conveying determination part107and a roller drive part109.

To the document placement determination part101, the signal output from the document placement detection sensor37is input. Based on the output signal, the document placement determination part101determines whether the document is placed on the lift member27or not.

The lift member drive part103controls the drive of the motor41which rotates the supporting shaft39of the lift member27.

To the roller height determination part105, the signal output from the optical sensor89of the upper limit detection part85is input. Based on the output signal, the roller height determination part105determines whether the feed roller67turns to the optimum feeding height or not. In the other words, when the output signal is input, it is also determined that the feed roller67, that is, the holder73turns upward.

To the document conveying determination part107, the signal output from the document passing detection sensor53is input. Based on the output signal, the document conveying determination part107determines whether the document passes through a predetermined position (a position where the document passing detection sensor53is arranged) or not.

The roller drive part109controls the drive of the motor75which rotates the feed roller67.

The operation panel17is a touch panel, for example. The operation panel17makes it possible to select various conditions regarding the document conveying operation by the user.

In the document conveying device5having the above described configuration, the document conveying operation at the one-side reading will be described with reference to the flowchart5shown inFIG. 5andFIG. 6AtoFIG. 6D.FIG. 6AtoFIG. 6Dare side views showing the lift member and the feed roller when the overload is determined.

The document conveying device5at an initial state will be described. As shown inFIG. 6A, at the initial state, the lift member27is turned to the home position. That is, the third conveying path45ais opened, and the lift member27is inclined downward so as to connect with the placement tray25. The holder73is biased by the spring81, and is turned downward.

First, the user places a bundle of the documents D on the placement tray25and the lift member27through the space between the feed roller67and the lift member27. The bundle of the documents D is placed such that the lead edges of the documents are butted on the abutment wall47a.Then, at step S1, the document placement determination part101determines that the bundle of the documents D is placed on the lift member27, and then it proceeds to step S2.

At step S2, the roller height determination part105determines whether the upper limit detection part85is operated or not (whether the upper limit detection part85outputs the signal or not). When the roller height determination part105determines that the upper limit detection part85is not operated, it proceeds to step S3. The case where the upper limit detection part85is not operated shows a case where the feed roller67is not pushed up higher than the optimum feeding height by the placed bundle of the documents D, for example, a case where a thickness of the bundle of the documents D is thinner than the space between the lift member27and the feed roller67. In this case, it is determined that the bundle of the documents D is not overloaded.

Then, at step S3, the lift member drive part103drives the motor41to turn the lift member27upward. Thereby, the feed roller67is pushed up by the uppermost document. Then, at step S4, when the roller height determination part105determines that the feed roller67is turned to the optimum feeding height, it proceeds to step S5. At step S5, the lift member drive part103stops the drive of the motor41. Thereby, the feed roller67turns to the optimum feeding height. Then, it proceeds to step S6. At step S6, the roller drive part109drives the motor75to rotate the feed roller67. As a result, the uppermost document is fed to the main conveying path43.

On the other hand, at step S2, when the roller height determination part105determines that the upper limit detection part85is operated, it proceeds to step S7. At step S7, the roller height determination part105determines that the placed bundle of the documents D is overloaded. That is, if the thickness of the bundle of the documents D is thicker than the space between the feed roller67and the lift member27at the initial state, when the bundle of the documents D is placed, as shown inFIG. 6B, the feed roller67is pushed up by the uppermost document, and the holder73is turned upward against the biasing force of the spring81. As a result, the protruding piece87of the holder73moves upward across the light path of the optical sensor89, the optical sensor89is switched from off to on and then outputs the signal. Then, the roller height determination part105determines that the bundle of the documents D is overloaded.

When the overload is determined at step S7, it proceeds to step S8. At step S8, the lift member drive part103drives the motor41to turn the lift member27downward. When the lift member27is turned downward, the holder73pushed up by the bundle of the documents D begins to turn downward by its own weight and the biasing force of the spring81. At this time, as shown inFIG. 6C, the lift member27may be turned downward over the home position so as to close the third conveying path45a.That is, because the document is not conveyed along the third conveying path45aat the one-side reading, if the third conveying path45amaybe closed, any problem is not caused.

Then, at step S9, the feed roller height determination part105determines whether the holder73is turned until the feed roller67is positioned lower than the optimum feeding height. When, at step S9, it is determined that the holder73is turned until the feed roller67is positioned lower than the optimum feeding height, it proceeds to step S10. At step10, the lift member drive part103stops the drive of the motor41, and then it proceeds to step S11.

At step S11, the lift member drive part103drives the motor41to turn the lift member27upward again. Then, at step S12, the roller height determination part105determines whether the holder73is turned until the feed roller67is pushed up by the uppermost document and positioned at the optimum feeding height. At step S12, when it is determined that the holder73is turned until the feed roller67is positioned at the optimum feeding height (refer toFIG. 6D), it proceeds to step S5. At step S5, the lift member drive part103stops the drive of the motor41, and then it proceeds to step S6. At step S6, the roller drive part109drives the motor75to rotate the feed roller67. Thereby, the uppermost document is fed to the main conveying path43. At this time, the lift member27is not necessarily turned to the home position, and may close a part of the third conveying path45a.

Next, the document conveying operation in the both-side reading when the overload is determined will be described with reference to a flowchart shown inFIG. 7.

Steps from S21to S28are the same as the steps of S7, S8, S9, S10, S11, S5and S6, and their explanations are omitted. In the both-side reading, after the uppermost document is fed at step S28, it proceeds to step S29. At step S29, the document conveying determination part107determines whether the uppermost document passes through the predetermined position or not. When the document conveying determination part107determines that the uppermost document passes through the predetermined position, it proceeds to step S30. The predetermined position shows any positions at the upstream side of a position where the uppermost document reaches the third conveying path45a.For example, the predetermined position may be a position where the document passing detection sensor53detects the uppermost document.

At step S30, the lift member drive part103drives the motor41to turn the lift member27upward. The lift member27is turned downward and then upward. However, when the lift member27is turned upward again at step S30, the lift member27may not be turned until the third conveying path45ais fully opened, depending on the thickness of the bundle of documents D. In the both-side reading, because the document is conveyed along the third conveying path45a,if the third conveying path45ais closed by the lift member27, a conveying failure of the document may occur. Thereby, at step S30, the lift member drive part103drives the motor41to turn the lift member27upward to open the third conveying path45a.

Then, at step S31, the lift member drive part103determines whether the motor41is driven for a predetermined period in a predetermined direction. The predetermined period shows a difference between a period T1and a period T2, for example, in which the period T1is a period from a time t1at which the motor41is driven to turn the lift member27downward from the home position at step S22to a time t2at which the drive of the motor41is stopped at step S24and the period T2is a period from a time t3at which the motor41is driven to turn the lift member27upward at step S25to a time t4at which the drive of the motor41is stopped at step S27. Thereby, the lift member27turns to the home position, and the third conveying path45ais suitably opened.

When it is determined that the lift member drive part103drives the motor41for the predetermined period at step S31, it proceeds to step S32. At step S32, the lift member drive part103stops the drive of the motor41. Thereby, after an image data of one face of the uppermost document is read at the image reading part59, the uppermost document is inverted through the third conveying path45awhich is suitable opened, and then an image data of the other face of the uppermost document is read at the image reading part59.

The document conveying operation described above is defined as an overload feeding mode. After the uppermost document is conveyed as described above, a conveying of a next document begins.

As described above, in the document conveying device5of the present disclosure, if the document is overloaded, the lift member27turns to close the third conveying path45aonce so that it becomes possible to convey the document without replacing the bundle of the documents and then to read the image data of the one face and the other face of the document. In addition, because the third conveying path45ais used as a space in which the lift member27is turned, it becomes possible to lower the height of the document conveying device5.

However, in the overload feeding mode, because the conveying of a second document begins after the conveying of a first document is finished, productivity of the conveying operation may be deteriorated. Then, if the overload is determined, the user may select whether the above overload feeding mode is executed or not. For example, the operation panel17is configured to include a display part displaying that the document is overloaded and a run button executing the overload feeding mode. When the display part displays that the document is overloaded and then the user operates the run button, the overload feeding mode is executed. On the other hand, when the overload feeding mode is not executed, the display part shows a message to remove the bundle of the documents and then to replace the bundle after the number of the documents is reduced.

In another embodiment, the home position of the lift member27may be detected by a lower limit detection part. The lower limit detection part includes a protruding piece provided at the downstream side end portion of the lift member27and an optical sensor provided at the main body, for example. The optical sensor includes a light emitting part and a light receiving part which face each other with a predetermined interval, and between the light emitting part and the light receiving part, a light path is formed. When the light path is closed, the optical sensor is switched from off to on, and outputs a signal. The optical sensor is positioned to the main body33such that the protruding piece of the lift member27turned to the home position is inserted between the light emitting part and the light receiving part, that is, the protruding piece closes the light path. By combining the output signal of the optical sensor of the lower limit detection part and the output signal of the optical sensor89of the upper limit detection sensor85, it can be determined whether the lift member27is turned lower or higher than the home position.

When the above lower limit detection part is provided, at step S7in the flowchart ofFIG. 7, when the lower limit detection part determines that the lift member27is turned to the home position, it proceeds to step S32. At step S32, the turning of the lift member27is stopped.

While the above description has been described with reference to the particular illustrative embodiments of the image forming apparatus according to the present disclosure, a technical range of the disclosure is not to be restricted by the description and illustration of the embodiment.