Document conveyance device and image forming apparatus

A document conveyance device according to the present disclosure includes a document conveyance path, a first actuator, a second actuator, and an optical sensor. The first actuator is disposed in the document conveyance path. The second actuator is disposed on a more downstream side than the first actuator in the document conveyance path in the document conveyance direction. An output state of the optical sensor is switched based on pivoting of the first actuator and second actuator. A tip end of the document passes the first actuator, whereby the optical sensor outputs a first output indicating a first state, the tip end of the document passes the second actuator, whereby the optical sensor outputs a second output indicating a second state, and a rear end of the document passes the first actuator, whereby the optical sensor outputs the first output.

INCORPORATION BY REFERENCE

The present application is based on Japanese Patent Application No. 2015-026402 filed of Feb. 13, 2015, the contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to a document conveyance device and an image forming apparatus that includes the document conveyance device, more particularly, to a document conveyance device that includes a sensor for detecting a document passing in a document conveyance path and an image forming apparatus that includes the document conveyance device.

There are some image forming apparatuses, such as a copy machine, a facsimile, a scanner and the like, include a document conveyance device that automatically sends a plurality of documents to a document reading portion. The document conveyance device separates documents from a bundle of documents loaded in a document placement tray one after another beginning with the uppermost document, and sends the documents to the document reading portion. After an image on a surface of the document is read by the document reading portion, the document is delivered to a document delivery tray that is disposed on the most downstream side of a document conveyance path.

For example, to count a reading start timing at the document reading portion, a next sheet feeding timing and the like, the document conveyance device needs to include a sensor that detects a tip end and rear end of the document. Because of this, a document conveyance device is known in which a document conveyance path is provided with only one sensor that detects presence of a document.

Besides, a document conveyance device is known in which a document conveyance path is provided with two sensors one of which detects a tip end of a document and the other of which detects a rear end of the document.

SUMMARY

A document conveyance device according to an aspect of the present disclosure includes a document conveyance path, a first actuator, a second actuator, and an optical sensor. A document passes through the document conveyance path. The first actuator is disposed in the document conveyance path and pivots in a predetermined direction by being butted by the document. The second actuator is disposed on a more downstream side than the first actuator in the document conveyance path in a document conveyance direction and pivots in the predetermined direction by being butted by the document. An output state of the optical sensor is switched based on the pivoting of the first actuator and second actuator. The optical sensor outputs: a first output indicating a first state in a state in which the document does not pass the first actuator and the second actuator; the first output in a state in which a tip end of the document passes the first actuator, whereby only the first actuator of the first actuator and second actuator pivots in the predetermined direction; a second output indicating a second state, different from the first state, in which the tip end of the document passes the second actuator, whereby both the first actuator and the second actuator pivot in the predetermined direction; and the first output in a state in which a rear end of the document passes the first actuator, whereby the first actuator pivots in a direction opposite to the predetermined direction and the second actuator pivots in the predetermined direction.

Still other objects of the present disclosure and specific advantages obtained by the present disclosure will become more apparent from the following description of a preferred embodiment.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure is described with reference to the drawings.

With reference toFIG. 1toFIG. 7, an image forming apparatus100including a document conveyance device27according to an embodiment of the present disclosure is described. InFIG. 1, in the image forming apparatus100(here, a digital multi-functional machine is shown as an example), in a case where a copy operation is performed, an image reading device6described later reads image data of a document and converts the image data into an image signal. On the other hand, in an image forming portion3in a multi-functional machine main body2, a photosensitive drum5, which rotates in a clockwise direction in the figure, is evenly electrified by the electrifying unit4, an electrostatic latent image is formed, based on the document image data read by the image reading device6, onto the photosensitive drum5by a laser beam from a light exposure unit (laser scanning unit and the like)7, a developer (hereinafter, called a toner) is made to adhere to the electrostatic latent image by a developing unit8, whereby a toner image is formed. Toner supply to the developing unit8is performed from a toner container9.

The image reading device6is disposed on the multi-functional machine main body2, an upper surface of the multi-functional machine main body2is provided with a platen (document pusher)24that is disposed in an openable and closable manner, pushes and holds the document placed on a contact glass (not shown) of the image reading device6, and the platen24is provided thereon with the document conveyance device27that automatically conveys the document to a document reading portion (not shown) of the image reading device6.

As shown inFIG. 2andFIG. 3, in a cover member31(seeFIG. 3) of the document conveyance device27, a document conveyance path d is formed which extends from a document feeding tray (document loading portion)29to a document delivery tray32, and along the document conveyance path d, a document conveyance member is disposed which is composed of a pickup roller33, a sheet feeding roller34, a separating plate35, conveyance roller pairs38,39,40, and a delivery roller pair41.

In the meantime, the document conveyance path d bends in substantially a U shape to make a U-turn between the sheet feeding roller34and the delivery roller pair41.

Next, a document conveyance operation of sheet-through type, which uses the document conveyance device27, is described. In the sheet-through type, a plurality of documents are set onto the document feeding tray29with an image surface facing upward, thereafter, when a copy start button on an operation panel30(seeFIG. 1) of the image forming apparatus100is turned on, a lift plate28stepped up by a stepping-up/down mechanism (not shown) pushes up the pickup roller33via the document, and a weight of a frame body (not shown) including the pickup roller33acts on the lift plate28, whereby an upper surface of the document is pushed against the pickup roller33with a predetermined pressure (sheet feeding pressure).

As to the documents loaded in the document feeding tray29, usually a plurality of upper documents are sent by the pickup roller33to a nip portion between the sheet feeding roller34and the separating plate35. And, of the plurality of documents, only the uppermost one is separated by the separating plate35and conveyed to the conveyance roller pair38.

The document is conveyed by the conveyance roller pairs38,39, and40to the delivery roller pair41via an automatic reading glass (not shown) of the contact glass, thereafter, finally delivered onto the document delivery tray32by the delivery roller pair41. At that time, a delivery sensor (not shown) detects passage of a rear end of the document, whereby completion of the image reading of the one document is detected.

In the meantime, as to the document, when passing the automatic reading glass (not shown), the image is read by an image reading portion of the image reading device6through the automatic reading glass (not shown).

Next, a structure of the document conveyance device27is described in detail.

As shown inFIG. 3, the document conveyance path d has a conveyance surface whose cross-section along the document conveyance direction is substantially a U-shape, is composed of an inner conveyance guide member60and an outer conveyance guide member61that guide the document.

As shown inFIG. 4, the pickup roller33has a rotation shaft33a, a roller body33bfixed to the rotation shaft33a. The rotation shaft33ais formed slightly longer than the roller body33b, and disposed on an inner side in a document width direction of a document passage region where the document passes.

The sheet feeding roller34has a rotation shaft34a, and a roller body34bfixed to the rotation shaft34a. As shown inFIG. 2, the rotation shaft34ais formed longer than the document passage region in the document width direction, and its one end portion and other end portion are supported rotatably by bearing members52,53that are disposed on outer sides of the inner conveyance guide member60and outer conveyance guide member61in the document width direction and compose a housing. Besides, the other end portion of the rotation shaft34ais provided with a drive gear (not shown), and a drive force from a drive motor (not shown) is transmitted via a plurality of transmission gears, a clutch and the like.

Besides, a central portion of the rotation shaft34ais provided with a holding member36that supports rotatably the pickup roller33. The holding member36is disposed swingably about the rotation shaft34aof the sheet feeding roller34. In the meantime, a drive force is transmitted from the sheet feeding roller34to the pickup roller33via an intermediate gear37(seeFIG. 4) that is disposed in the holding member36.

As shown inFIG. 3, the conveyance roller pairs38,39,40, and the delivery roller pair41include conveyance rollers38a,39a,40a, and41athat are disposed on an inner circumferential side of a conveyance surface of the inner conveyance guide member60and pulleys38b,39b,40b, and41bthat are disposed on an outer side of a conveyance surface of the outer conveyance guide member61. The pulleys38b,39b,40b, and41bpush the conveyance rollers38a,39a,40a, and41aagainst the inner circumferential side of the inner conveyance guide member60, and are driven to rotate by rotations of the conveyance rollers38a,39a,40a, and41a.

Besides, a contact image sensor (reading portion)45is disposed between the conveyance roller pair38and the conveyance roller pair39. The contact image sensor45reads an image on a rear surface of the document conveyed in the document conveyance path d.

Here, in the present embodiment, as shown inFIG. 4, a first actuator51, which pivots in a counterclockwise direction (arrow A direction, predetermined direction) by being butted by the document, is disposed at a position of the document conveyance path d between the sheet feeding roller34and the conveyance roller pair38, and a second actuator52, which pivots in the counterclockwise direction by being butted by the document, is disposed on a more downstream side than the first actuator51in the document conveyance direction. The second actuator52is disposed at a position of the document conveyance path d between the conveyance roller pair38and the contact image sensor45.

Besides, an optical sensor53(hereinafter, called a sensor53), whose output state is switched based on the pivoting of the first actuator51and second actuator52, is disposed below the second actuator52.

The sensor53is a transmission type sensor, and has a light casting portion53a(seeFIG. 6) and a light receiving portion (not shown) that are disposed across a predetermined interval in the document width direction (direction perpendicular to the paper surface ofFIG. 4). In a case where the light emitted from the light casting portion53ais received by the light receiving portion, the sensor53goes to a transmission state (e.g., on-state), and in a case where the light emitted from the light casting portion53ais not received by the light receiving portion, the sensor53goes to a light blocking state (e.g., off-state).

The first actuator51is disposed near an end portion (left end portion) of the holding member36on the downstream side in the document conveyance direction. Besides, the first actuator51has a rotation shaft51a, a butted portion51bthat extends upward from the rotation shaft51aand is butted by the document, and a first light blocking portion51cthat extends downward from the rotation shaft51aand is able to switch the sensor53between a light blocking state and a transmission state.

The butted portion51bis formed to go through the document conveyance path d in a vertical direction, and the inner conveyance guide member60and the outer conveyance guide member61are provided with slits, which allow a swing of the butted portion51b, at positions corresponding to the butted portion51b.

Besides, the first actuator51is biased in a clockwise direction (arrow B direction) by a torsion spring54disposed on the rotation shaft51a. Because of this, in a state (state ofFIG. 4) in which the butted portion51bis not butted by the document, the first actuator51is disposed at a first position (first posture) where the first light blocking portion51cis disposed between the light casting portion53aand light receiving portion of the sensor53. Besides, in a state (state ofFIG. 5) in which the butted portion51bis butted by the document to pivot in the counterclockwise direction (arrow A direction), the first actuator51is disposed at a second position (second posture) where the first light blocking portion51cis not disposed between the light casting portion53aand light receiving portion of the sensor53. In the meantime, the pivoting of the first actuator51in the clockwise direction is restricted by an end edge of the slit.

The second actuator52has a rotation shaft52a, a butted portion52bthat extends upward from the rotation shaft52aand is butted by the document, and a second light blocking portion52cthat extends downward from the rotation shaft52aand is able to switch the sensor53between the light blocking state and the transmission state.

The butted portion52bis formed to go through the document conveyance path d in the vertical direction, and the inner conveyance guide member60and the outer conveyance guide member61are provided with slits, which allow a swing of the butted portion52b, at positions corresponding to the butted portion52b.

Besides, the second actuator52is biased in the clockwise direction (arrow B direction) by a torsion spring55disposed on the rotation shaft52a. Because of this, in a state (state ofFIG. 4) in which the butted portion52bis not butted by the document, the second actuator52is disposed at a third position (third posture) where the second light blocking portion52cis disposed between the light casting portion53aand light receiving portion of the sensor53. Besides, in a state (state ofFIG. 6) in which the butted portion52bis butted by the document to pivot in the counterclockwise direction (arrow A direction), the second actuator52is disposed at a fourth position (fourth posture) where the second light blocking portion52cis not disposed between the light casting portion53aand light receiving portion of the sensor53. In the meantime, the pivoting of the second actuator52in the clockwise direction is restricted by an end edge of the slit.

In the document conveyance device27, in the state (initial state) in which the document does not pass the first actuator51and the second actuator52, as shown inFIG. 4, the first actuator51is disposed at the first position and the second actuator52is disposed at the third position. Because of this, the sensor53goes to the light blocking state (first state) to output a first output that indicates the light blocking state.

And, a sheet feeding operation by the pickup roller33and sheet feeding roller34is started, and when the tip end of the document passes the first actuator51, as shown inFIG. 5, only the first actuator51of the first actuator51and second actuator52pivots in the counterclockwise direction (arrow A direction, predetermined direction). In this way, the first actuator51is disposed at the second position. At this time, the second actuator52is disposed at the third position. Accordingly, the sensor53keeps the light blocking state to output the first output that indicates the light blocking state.

Thereafter, when the tip end of the document passes the second actuator52, as shown inFIG. 6, the second actuator52pivots in the counterclockwise direction (arrow A direction), whereby both the first actuator51and the second actuator52go to a state to pivot in the counterclockwise direction (arrow A direction). In this way, the first actuator51is disposed at the second position, and the second actuator52is disposed at the fourth position. Because of this, the sensor53switches to the transmission state (second state) to output a second output that indicates the transmission state. As described above, the output from the sensor53switches from the first output to the second output, whereby a control portion (not shown) is able to detect the tip end of the document and count an image reading timing for the contact image sensor45.

And, when the rear end of the document passes the first actuator51, as shown inFIG. 7, only the first actuator51of the first actuator51and second actuator52pivots in the clockwise direction (arrow B direction). In this way, the first actuator51is disposed at the first position. Because of this, the sensor53switches to the light blocking state to output the first output that indicates the light blocking state. As described above, the output from the sensor53switches from the second output to the first output, whereby the control portion (not shown) is able to detect the rear end of the document and count a timing for the next sheet feeding.

Thereafter, when the rear end of the document passes the second actuator52, as shown inFIG. 4, the second actuator52pivots in the clockwise direction (arrow B direction), whereby both the first actuator51and the second actuator52go to a state (return to the initial state) to pivot in the clockwise direction (arrow B direction). In this way, the first actuator51is disposed at the first position, and the second actuator52is disposed at the second position. Because of this, the sensor53keeps the light blocking state to output the first output that indicates the light blocking state.

In the present embodiment, as described above, the tip end of the document passes the second actuator52, whereby the output from the sensor53changes from the first output to the second output, while the rear end of the document passes the first actuator51, whereby the output from the sensor53changes from the second output to the first output. Because of this, it is possible to detect the tip end and rear end of the document by means of the one sensor53and the two actuators (51,52). Accordingly, compared with the case where two sensors are disposed, it is possible to alleviate the cost becoming high.

Besides, by disposing the first actuator51, which detects the rear end of the document, on a more upstream side than the second actuator52for detecting the tip end of the document in the document conveyance direction, it is possible to move the first actuator51close to the sheet feeding roller34, and it is possible to shorten a period from a time the document in the document feeding tray29is fed to a time the rear end of the document is detected. In this way, it is possible to advance the timing for the next sheet feeding (shorten the time interval between the sheet feedings).

Besides, as described above, the first actuator51is disposed between the sheet feeding roller34and the conveyance roller pair38, whereby it is possible to easily move the first actuator51close to the sheet feeding roller34, and it is possible to easily shorten the period from the time the document is fed to the time the rear end of the document is detected. Besides, the second actuator52is disposed between the conveyance roller pair38and the contact image sensor45, whereby the tip end of the document is detected with the document nipped by the conveyance roller pair38. In this way, it is possible to increase accuracy of the image reading timing for the contact image sensor45.

Besides, as described above, a transmission type sensor is used as the sensor53, whereby it is possible to more curb the cost compared with a case where a reflection type sensor is used, for example.

Besides, as described above, the first actuator51has the first light blocking portion51cand the second actuator52has the second light blocking portion52c. Because of this, it is possible to easily switch the sensor53between the light blocking state and the transmission state.

Besides, as described above, the first actuator51is disposed near the end portion of the holding member36on the downstream side in the document conveyance direction. Because of this, it is possible to move the first actuator51as close to the sheet feeding roller34as possible. Accordingly, it is possible to make the period from the time the document is fed to the time the rear end of the document is detected as short as possible.

In the meantime, the embodiment disclosed this time is an example in all respects and is not limiting. The scope of the present disclosure is not indicated by the above description of the embodiment but by the claims, and all modifications within the scope of the claim and the meaning equivalent to the claim are covered.

For example, in the above embodiment, the example is described, in which a transmission type sensor is used as the optical sensor, but the present disclosure is not limited to this, and it is also possible to use a reflection type sensor as the optical sensor. In this case, the reflection type sensor may be structured in such a way that the light receiving portion detects the light that is emitted from the light casting portion and reflected by the actuator. Besides, the reflection type sensor may be structured in which a reflection member is disposed to oppose the light casting portion and the light receiving portion detects the light that is emitted from the light casting portion and reflected by the reflection member.