JP2007153533A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of stably carrying a carrying object by eliminating jam by staying on a carrying passage, by surely detecting a carrying abnormality and the double feeding of the carrying object such as a recording medium and a document by a simple constitution. <P>SOLUTION: This image forming device 1A has a paper carrying passage 7a constituting a carrying means for carrying paper P and a paper detecting sensor 171 detecting the carried paper P, and is characterized in that the paper detecting sensor 171 is arranged on the paper carrying passage 7a carrying the paper P, and has a paper jam detecting function 172 for detecting whether or not the paper P is normally carried by detecting the carrying state of the paper P. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and in particular, is applied to a copying machine, a multifunction machine, a printer, a facsimile, etc. using an electrophotographic system so as to detect a conveyance state of a document or recording paper conveyed in the apparatus. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus includes a paper cassette that stores a plurality of recording sheets, and can easily supply a plurality of documents by automatically feeding a plurality of sheets by automatic feeding. An automatic document reader is provided to facilitate printing operations.

  However, in the automatic supply of recording paper and manuscripts, there are cases where the paper is unintentionally double-fed or a paper jam occurs.

  Therefore, as a countermeasure against the above-described problem, when a recording paper double feed occurs when supplying recording paper for printing in an image forming apparatus, an ultrasonic double feed detection sensor is used. When a double feed of a read document occurs when a document is read (refer to Patent Document 1) or when a document is read, an ultrasonic double feed detection sensor is used. A device that detects feeding is disclosed (see Patent Document 2).

  What is shown in the above prior art is a content that uses an ultrasonic double feed detection sensor to surely detect a double feed when a double feed occurs on a read original or a recording paper for printing. It is shown.

  Unlike conventional methods, this ultrasonic multi-feed detection sensor can detect multi-feed without contact with the original or recording paper, so that it does not interfere with the transport of the transported object, and the color and thickness of the recording paper. This makes it possible to reliably detect double feed of recording paper without involvement.

  The above-described prior art detects double feeding when a document placed on a document placement table or a recording sheet stored in a sheet feeding cassette is fed by a sheet feeding means or the like. This is to detect double feeding when more than one sheet is fed.

As a method for detecting the presence or absence of a document or recording paper, a method in which a mechanical microswitch or the like is provided in the conveyance path of the document or recording paper is widely used.
These switches are provided with actuators, and when the tips of the actuators contact the recording paper, the microswitch contacts are operated to detect the presence or absence of the recording paper.
JP 2002-333797 A JP 2006-303375 A

However, the detection method using the mechanical sensor has a problem that the arrangement of the actuators is limited so as not to hinder the conveyance of the recording paper.
In the case of the mechanical sensor, when the recording paper is lifted for some reason, it is in a state where it does not come into contact with the actuator, and there is a problem that it may not be detected despite the presence of the recording paper.

  The present invention has been made in view of the above-described conventional problems, and reliably detects a conveyance abnormality or double feeding of a conveyance object such as a recording medium or a document with a simple configuration and stays on the conveyance path. It is an object of the present invention to provide an image forming apparatus that eliminates the jam caused by the above and can realize stable conveyance of the conveyed product.

The configuration of the image forming apparatus according to the present invention for solving the above-described problems is as follows.
The image forming apparatus according to claim 1, further comprising: a conveyance unit that conveys a document or a recording medium as a conveyance object; and a conveyance detection unit that detects the conveyance object conveyed by the conveyance unit. A detection means is provided on the transport path for transporting the transported object, and has a paper jam detection function for detecting whether the transported object is normally transported by detecting the transport state of the transported object. It is characterized by that.

  The image forming apparatus described in claim 2 is characterized in that, in addition to the structure described in claim 1, a transmission type sensor using ultrasonic waves is used as the structure of the conveyance detecting means.

  According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the image forming apparatus has the paper jam detection function, wherein at least a part of the conveyed product is either S-shaped or Z-shaped. It is characterized in that the state is detected.

  In addition to the structure described in any one of claims 1 to 3, the image forming apparatus described in claim 4 is configured such that the transport detection unit detects a front end of the transported object, and It has a rear end detection function for detecting the rear end.

  According to a fifth aspect of the present invention, in addition to the configuration described in any one of the first to fourth aspects, the image forming apparatus further includes a conveyance detecting unit configured to detect the conveyance object being double-fed. It is characterized by having a feed detection function.

  According to a sixth aspect of the present invention, in addition to the configuration described in any one of the first to fifth aspects, the image forming apparatus includes an automatic document reading device that automatically conveys a document and reads image information of the document. The conveyance detection means is arranged on the upstream side in the document conveyance direction with respect to the image reading unit provided in the automatic document reading apparatus.

  An image forming apparatus according to a seventh aspect of the invention includes an electrostatic latent image carrier on which a developer image is formed by a developer, in addition to the configuration described in any one of the first to sixth aspects, and a recording A transfer means for transferring the medium along the surface of the latent electrostatic image bearing member; a transfer means for transferring a developer image on the surface of the latent electrostatic image bearing member to the recording medium; And a fixing means for fixing the developer image to the recording medium, and transferring the developer image formed on the surface of the electrostatic latent image carrier onto the recording medium to output an image. The transport detection unit is arranged at least at a position upstream of the transfer unit in the recording medium transport direction or upstream of the fixing unit in the recording medium transport direction.

  According to an eighth aspect of the present invention, in addition to the configuration described in any one of the first to seventh aspects, the image forming apparatus includes a post-processing device that performs a paper discharge process for a recording medium that is discharged after the image formation. And the conveyance detecting means is arranged on the upstream side in the recording medium conveyance direction of the recording medium conveyance path formed in the post-processing apparatus.

  According to the first aspect of the present invention, in the image forming apparatus comprising: a conveying unit that conveys a document or a recording medium as a conveyed item; and a conveyance detecting unit that detects the conveyed item conveyed by the conveying unit. The detection means is disposed on a transport path through which the transported object is transported, and has a paper jam detection function for detecting whether the transported object is normally transported by detecting a transport state of the transported object. Therefore, without providing a separate sensor, it is possible to reliably detect conveyance abnormalities and multi-feeds with a simple configuration, eliminate jamming due to staying on the conveyance path, and realize stable conveyance of conveyed items. .

  Moreover, according to invention of Claims 2-8, in addition to the said common effect obtained by the invention of Claim 1, the following effect can be acquired.

  That is, according to the invention described in claim 2, by using a transmission type sensor using ultrasonic waves as the configuration of the conveyance detection means, it is not affected by the material such as the thickness and color of the conveyed object, The directivity of the sensor can be widened.

  According to the invention described in claim 3, the paper jam detection function detects that at least a part of the conveyed product is in an S-shaped or Z-shaped state. When the shape is bent due to abnormal conveyance or the like, and normal conveyance is difficult to be performed, it is possible to detect the abnormal shape of the conveyed object and detect a jam.

  According to the invention described in claim 4, the transport detection means has a front end detection function for detecting the front end of the transport object and a rear end detection function for detecting the rear end. Detection and rear end detection can be easily performed.

  According to the invention described in claim 5, since the transport detection means has a double feed detection function for detecting that the transport object is double-fed, when the transport object is double-fed, Jam can be suppressed by assuming that the conveyance is not normal.

  According to the sixth aspect of the present invention, an automatic document reading device that automatically conveys a document and reads image information of the document is provided, and the conveyance detection means is provided by an image reading unit provided in the automatic document reading device. In addition, by arranging it at the upstream side in the document conveying direction, it is possible to easily detect a jam occurring in the automatic document reading apparatus.

  According to the seventh aspect of the present invention, the electrostatic latent image carrier on which the developer image is formed by the developer, and the conveyance means for conveying the recording medium along the surface of the electrostatic latent image carrier; A transfer means for transferring the developer image on the surface of the electrostatic latent image carrier to a recording medium; and a fixing means for fixing the developer image transferred on the recording medium to the recording medium. An image forming apparatus configured to transfer a developer image formed on a surface of an image carrier onto a recording medium to output an image, wherein the conveyance detecting unit is at least upstream of the transfer unit in the recording medium conveying direction. Jam that occurs on the upstream side in the recording medium conveyance direction of the transfer unit or the fixing unit can be detected instantaneously.

  According to an eighth aspect of the present invention, the image forming apparatus includes a post-processing device that discharges a recording medium that is discharged after the image is formed, and the conveyance detection unit is formed in the post-processing device. The jam can be detected instantaneously on the upstream side of the post-processing device in the recording medium conveyance direction, and the influence of the jam on the post-processing device is minimized. can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 are examples of embodiments for carrying out the present invention. FIG. 1 is an explanatory diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a main body of the image forming apparatus. FIG.

  The image forming apparatus 1A according to the present embodiment uses a predetermined sheet-like recording sheet (hereinafter, referred to as a sheet) that serves as a recording medium by electrophotographic processing of image data read by a scanner or the like or image data transmitted from the outside. .) Is an image forming apparatus that outputs and forms a monochrome (single color) image, and includes a sheet conveying path 7a and a sheet conveying path 7a that constitute a sheet conveying apparatus (conveying means) 7 that conveys the sheet P (recording medium). The apparatus includes a sheet detection sensor 171 (see FIGS. 5 and 6) that constitutes a sheet conveyance detection device (conveyance detection means) 170 (see FIGS. 5 and 6) that detects the sheet P conveyed through. The paper detection sensor 171 is disposed on the paper transport path 7a, and can detect whether or not the paper P is normally transported by detecting the transport state of the paper P.

  First, the overall configuration of the image forming apparatus 1A according to the present embodiment will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 </ b> A mainly includes an exposure unit 1, a developing device 2, a photosensitive drum 3, a charger 4, a charge eliminating device 41, a cleaner unit 5, a fixing unit 6, and a sheet conveyance path. 7a, an apparatus main body 1A1 including a paper feed tray 8, a paper discharge tray 9, a transfer mechanism (transfer means) 10, and the like, and an automatic document processing apparatus 1A2.

  A document placing table 21 made of transparent glass on which a document is placed is provided on the upper surface of the apparatus main body 1A1. Above the document placing table 21, the automatic document processing device 1A2 is swingably opened upward. On the other hand, a scanner unit 22 serving as a document reading unit that reads image information of a document is disposed below the document placing table 21.

  Below the scanner unit 22, an exposure unit 1, a developing device 2, a photosensitive drum 3, a charger 4, a static eliminator 41, a cleaner unit 5, a fixing unit 6, a paper transport path 7a, a paper discharge tray 9, and a transfer mechanism. 10 is disposed, and a paper feed tray 8 in which the paper P is stored is disposed below.

  The exposure unit 1 performs exposure by irradiating the surface of the photosensitive drum 3 uniformly charged by the charger 4 with laser light according to image data (image information for printing) output from an image processing unit (not shown). Thus, it has a function of writing and forming an electrostatic latent image corresponding to image data on the surface of the photosensitive drum 3.

  The exposure unit 1 is disposed immediately below the scanner unit 22 and above the photosensitive drum 3, and employs laser scanning units (LSU) 13 a and 13 b including a laser irradiation unit 11 and a reflection mirror 12. In the present embodiment, in order to perform high-speed printing processing, a technique of using a plurality of laser beams to reduce the irradiation timing is adopted, and a two-beam technique is adopted.

  In this embodiment, the laser scanning units (LSU) 13a and 13b are used for the exposure unit 1, but a light emitting element arranged in an array, for example, an EL or LED writing head may be used. .

  As shown in FIG. 2, the photosensitive drum 3 has a cylindrical shape, is disposed below the exposure unit 1, and is rotated in a predetermined direction (the direction of arrow A in the figure) by a driving unit and a control unit (not shown). Is controlled. Along the outer peripheral surface of the photosensitive drum 3, the sheet peeling claw 31, the cleaner unit 5, the charger 4 as an electric field generating unit, and the development head toward the downstream side in the rotational direction of the photosensitive drum with reference to the position after completion of image transfer. The device 2 and the static eliminator 41 are arranged in this order.

  The sheet peeling claw 31 is disposed so as to be able to contact and separate from the outer peripheral surface of the photosensitive drum 3 by a solenoid 32. The sheet peeling claw 31 is stuck to the surface of the photosensitive drum 3 when the unfixed toner image on the photosensitive drum 3 is transferred to the sheet P in a state of being in contact with the outer peripheral surface of the photosensitive drum 3. The sheet P is peeled off.

  Note that a driving motor or the like may be employed as the driving means for the sheet peeling claw 31 instead of the solenoid 32, and other driving means may be selected.

  The developing device 2 visualizes the electrostatic latent image formed on the photosensitive drum 3 with black toner, and is downstream of the charger 4 in the rotating direction of the photosensitive drum (the direction of arrow A in the figure). It is arranged substantially horizontally (right side in the figure) on the side of the photosensitive drum 3. A registration roller 15 is disposed below the developing unit 2 on the upstream side in the recording medium conveyance direction.

  The registration roller 15 aligns the front end of the paper P supplied from the paper feed tray 8 and the toner image on the photoconductive drum 3 and conveys it between the photoconductive drum 3 and the transfer belt 103 (not shown). The operation is controlled by the drive means and the control means.

The charger 4 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential, and is disposed above the photosensitive drum 3 and in the vicinity of the outer peripheral surface thereof.
In this embodiment, the charger type charger 4 is used. However, a contact type roller type or a brush type may be used.

  The static eliminator 41 is a pre-transfer static eliminator for reducing the surface potential of the photosensitive drum 3 in order to facilitate the transfer of the toner image formed on the surface of the photosensitive drum 3 to the paper P. It is arranged downstream of the developing device 2 in the drum rotating direction and close to the outer peripheral surface below the photosensitive drum 3.

  In the present embodiment, the static eliminator 41 is configured using a static elimination electrode. However, a static elimination lamp may be used in place of the static elimination electrode, or other static elimination may be used.

  The cleaner unit 5 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer. The cleaner unit 5 is located at a position substantially opposite to the developing device 2 with the photosensitive drum 3 interposed therebetween. The drum 3 is disposed substantially horizontally (left side in the drawing) on the side.

As described above, the electrostatic image visualized on the photosensitive drum 3 is applied from the transfer mechanism 10 onto the paper P on which the electric field having the opposite polarity to the charge of the electrostatic image is conveyed. Transferred onto P.
For example, when the electrostatic image has a charge of (−) polarity, the applied polarity of the transfer mechanism 10 is (+) polarity.

  As shown in FIG. 2, the transfer mechanism 10 is bridged by a driving roller 101, a driven roller 102, and other rollers, and has a predetermined resistance value (in this embodiment, a range of 1 × 10 9 to 1 × 10 13 Ω · cm). A transfer belt unit having a transfer belt 103 is disposed, and is arranged below the photosensitive drum 3 so that the surface of the transfer belt 103 is in contact with a part of the outer peripheral surface of the photosensitive drum 3. . The transfer belt 103 conveys the paper P while pressing it against the photosensitive drum 3.

  An elastic conductive roller 105 capable of applying a transfer electric field with a conductivity different from that of the driving roller 101 and the driven roller 102 is disposed at the contact portion 104 between the photosensitive drum 3 and the transfer belt 103.

  The elastic conductive roller 105 is made of a soft material such as elastic rubber or foamable resin. Since the elastic conductive roller 105 has elasticity, the photosensitive drum 3 and the transfer belt 103 are not in line contact but in surface contact having a predetermined width (referred to as a transfer nip), so that the sheet P to be conveyed is conveyed. The transfer efficiency can be improved.

  Further, on the downstream side of the transfer area of the transfer belt 103 in the sheet conveyance direction, a discharge roller 106 for discharging the electric field applied to the sheet P to be transferred in the transfer area and smoothly transferring to the next process is transferred. It is arranged on the back side of the belt 103.

  In addition, the transfer mechanism 10 is provided with a cleaning unit 107 that removes dirt from the residual toner on the transfer belt 103 and a plurality of charge removal mechanisms 108 that perform charge removal on the transfer belt 103. As a technique for performing static elimination used in the static elimination mechanism 108, there is a technique of grounding through an apparatus, or a technique of positively applying a polarity opposite to the polarity of the transfer electric field.

  The electrostatic image (unfixed toner) transferred onto the paper P by the transfer mechanism 10 is conveyed to the fixing unit 6 and is pressurized and heated to melt the unfixed toner and be fixed on the paper P. .

  As shown in FIG. 2, the fixing unit 6 includes a heating roller 6a and a pressure roller 6b. The heating roller 6a is rotated while the paper P is sandwiched between the heating roller 6a and the pressure roller 6b, and heated. By passing between the roller 6a and the pressure roller 6b, the toner image transferred onto the paper P is melted and fixed.

  A conveyance roller 16 that conveys the paper P is provided downstream of the fixing unit 6 in the paper conveyance direction.

  The heating roller 6a is provided with a sheet peeling claw 611, a roller surface temperature detecting member (thermistor) 612, and a roller surface cleaning member 613 on the outer peripheral portion, and the heating roller surface is set to a predetermined temperature (fixing set temperature) on the inner peripheral portion. : Approximately 160 to 200 ° C.).

  The pressure roller 6b is provided with a pressure member 621 that allows the pressure roller 6b to come into pressure contact with the heating roller 6a at a predetermined pressure amount at both ends of the roller. Further, the pressure roller 6b is heated on the outer periphery of the pressure roller 6b. Similarly to the outer periphery of the roller 6a, a sheet peeling claw 622 and a roller surface cleaning member 623 are arranged.

  As shown in FIG. 2, the fixing unit 6 is configured to remove unfixed toner on the conveyed paper P at a pressure contact portion (called a so-called fixing nip portion) 600 between the heating roller 6a and the pressure roller 6b. The unfixed toner is fixed on the paper P by the application of the heat applied by the heat roller 6a to melt and the throwing action on the paper P by the pressure contact force between the heating roller 6a and the pressure roller 6b.

  The paper feed tray 8 is used for accumulating a plurality of sheets (paper sheets) on which image information is output (printed). The exposure unit 1, the developing device 2, the photosensitive drum 3, the charger 4, and the charge eliminating device. The image forming unit 14 is configured below the image forming unit 14 including the apparatus 41, the cleaner unit 5, the fixing unit 6, and the like. A paper pickup roller 8a and transport rollers 8b and 8c are disposed on the upper side of the paper discharge side of the paper feed tray 8 (see FIG. 3).

  The paper P loaded in the paper feed tray 8 is picked up one by one from the uppermost layer by the paper pick-up roller 8a, and the paper P is transported downstream in the paper transport direction by the transport rollers 8b and 8c (for convenience, paper The flow side (cassette side) of P is upstream and the discharge side is downstream.) The sheet is conveyed to a registration roller (also referred to as “idle roller”) 15 side on the sheet conveyance path 7a.

  In the image forming apparatus 1A according to the present embodiment, in order to perform high-speed printing processing, a plurality of paper supply units capable of storing 500 to 1500 sheets of standard size sheets P in each tray are provided below the image forming unit 14. A paper tray 8 is disposed, and on the other hand, a large-capacity paper feed cassette 81 capable of storing a large amount of a plurality of paper types is disposed on the side of the apparatus, and an irregular type is mainly disposed above the large-capacity paper feed cassette 81. A manual feed tray 82 corresponding to size printing or the like is provided.

  The paper discharge tray 9 is disposed on the side of the apparatus opposite to the manual feed tray 82. Further, instead of the paper discharge tray 9, a post-processing device (device for performing stapling, punching, etc.) of paper discharge, a multi-stage paper discharge tray, and the like can be arranged as options.

  The paper transport path 7a is configured between the above-described photosensitive drum 3 and the paper feed tray 8, and transports the paper P supplied from the paper feed tray 8 to the transfer mechanism 10 one by one. A sheet on which the toner image is transferred from the photosensitive drum 3 is conveyed to the fixing unit 6, and after the unfixed toner image is fixed on the sheet in the fixing unit 6, a sheet conveyance path formed according to the designated processing mode. In addition, the sheet is conveyed by a branching claw.

Here, the sheet conveyance path 7a will be described in detail with reference to the drawings.
FIG. 3 is an explanatory diagram showing the configuration of the sheet conveyance path of the image forming apparatus according to the present embodiment, and FIG. 4 is a portion showing the configuration of the branched sheet conveyance path constituting the sheet conveyance path and the branching claw for communicating them. FIG.

  As shown in FIGS. 3 and 4, the sheet conveyance path 7 a mainly includes the first sheet conveyance path 7 a 1 from the sheet feed tray 8 to the registration roller 15, and the fixing unit 6 from the registration roller 15 via the transfer mechanism 10. The second paper transport path 7a2 that passes through and reaches the downstream transport roller 16, the third paper transport path 7a3 that reaches the paper discharge roller 17 for discharging the paper from the transport roller 16 to the paper discharge tray 9, and the transport roller 16 The fourth paper transport path 7a4 for reversing the paper P from the first paper, the fifth paper transport path 7a5 communicating with the fourth paper transport path 7a4 and the reverse transport roller 18 for transporting the paper P to the registration roller 15 again, the paper discharge roller A sixth paper transport path 7a6 that reverses from 17 and transports the paper P, a seventh paper transport path 7a7 that communicates with the sixth paper transport path and avoids the fifth paper transport path 7a5, and a seventh paper transport path 7a7 Communicate and switch It is composed of the eighth sheet conveying path 7a8 leading the back roller 19.

  A plurality of sheets P are arranged in the sheet transport path 7a according to the processing mode. In this embodiment, as shown in FIG. 3, eight sheets P of (1) to (8) (indicated by the circled numbers in the figure) are arranged in the sheet transport path 7a. The number of sheets P allowed in the sheet conveyance path can be changed in any way depending on the configuration of the sheet conveyance path.

  In the paper transport path 7a, a plurality of branching claws that change the transport path of the paper P by selecting the paper transport path according to the selected processing mode are provided at the branch points of the paper transport path. .

  As shown in FIG. 4, in the vicinity of the downstream side of the transport roller 16, a branch claw 20a that communicates with the third paper transport path 7a3 or the fourth paper transport path 7a4 is provided so as to be able to swing and displace. The branch claw 20a is operated by a solenoid (not shown).

  On the downstream side of the fourth paper transport path 7a4, a branch claw 20b that connects the fourth paper transport path 7a4 and the fifth paper transport path 7a5 or the fifth paper transport path 7a5 and the sixth paper transport path 7a6 swings. Displaceable. The branch claw 20b is operated by a spring member (not shown) and the elastic force of the paper P.

  On the downstream side of the sixth paper conveyance path 7a6, a branch claw 20c communicating with the fifth paper conveyance path 7a5 or the seventh paper conveyance path 7a7 is provided so as to be able to swing and displace. The branch claw 20c is operated by a solenoid (not shown).

  On the downstream side of the seventh paper transport path 7a7, a branch claw 20d that connects the seventh paper transport path 7a7 and the eighth paper transport path 7a8 or the fifth paper transport path 7a5 and the eighth paper transport path 7a8 is rocked. It is provided so that it can be displaced dynamically. The branch claw 20d is operated by a solenoid (not shown).

  On the upstream side of the fifth paper transport path 7a5, a branch claw 20e is provided for smoothly connecting the fourth paper transport path 7a4 and the eighth paper transport path 7a8 and the fifth paper transport path 7a5.

  With the paper conveyance path 7a configured as described above, the branch claws 20a to 20d are operated according to the requested processing mode, and the conveyance path of the paper P corresponding to the processing mode can be selected.

  Here, a sheet conveying process corresponding to the processing mode of the image forming apparatus 1A will be described with reference to the drawings.

As shown in FIG. 3, the paper P that matches the print request is selected from the plurality of paper feed trays 8 and is transported to the registration rollers 15 by the transport rollers in the paper transport path 7a.
The paper P that has reached the registration roller 15 and has stopped once is conveyed to the transfer mechanism 10 by the rotation of the registration roller again at the timing when the leading edge of the paper P and the image information on the photosensitive drum 3 coincide with each other. After an unfixed toner image (image information) is transferred from the photosensitive drum 3 to the top, the toner image is fixed on the paper P by the fixing unit 6 and is discharged to the paper discharge tray 9.

  In the conveyance path in the sheet conveyance path 7a, the sheet discharge tray from the fixing unit 6 onward is processed by the processing mode (copier mode, printer mode, FAX mode) of the image forming apparatus 1A and the printing processing method (single-sided printing, duplex printing). The transport method up to 9 is different.

  Normally, in the copier mode, since the user performs an operation in the vicinity of the image forming apparatus 1A, a method called “face-up discharge” in which the printing surface is discharged with its upper side being used is often used.

  On the other hand, in each mode such as printer, FAX, etc., a “face-down discharge” method that aligns the page order of the discharged paper P because the user is not in the vicinity of the image forming apparatus 1A is often used.

  Accordingly, in the image forming apparatus 1A, the sheet P meeting the above purpose is discharged through the plurality of transport paths and the plurality of branch claws until the sheet P that has passed through the fixing unit 6 is discharged to the sheet discharge tray 9. Is supposed to do.

(Face-up discharge with single-sided printing)
In the image forming apparatus 1A, in the case of the single-sided printing of the paper P and the face-up discharge method, the branch claw 20a has a claw position switching unit (not shown) immediately before the paper P that has passed the fixing unit 6 passes the transport roller 16. The third paper transport path 7a3 is opened by a solenoid or the like, and the fourth paper transport path 7a4 is shielded.

  The leading end of the transported paper P is navigated to the branching claw 20a, passes through the third paper transport path 7a3, and is discharged to the paper discharge tray 9 through the paper discharge roller 17.

(Face-down discharge with single-sided printing)
In the image forming apparatus 1A, in the case of the single-sided printing of the paper P and the face-down discharge method, the branching claw 20a has a claw position switching unit (not shown) immediately before the paper P that has passed the fixing unit 6 passes the transport roller 16. (Solenoid or the like) opens the fourth paper transport path 7a4 and shields the third paper transport path 7a3.

  Further, the branching claw 20c opens the fifth paper conveyance path 7a5 and shields the seventh paper conveyance path 7a7 by a claw position switching means (not shown).

  The transported paper P is navigated to the branch claw 20a by the leading end of the paper P and passes through the fourth paper transport path 7a4, and the branch claw 20b is moved by the waist (material strength) of the front end of the paper P and the transport force. Then, after the fifth paper transport path 7a5 is opened, it is navigated to the branch claw 20c and guided to the fifth paper transport path 7a5.

When the trailing edge of the paper P reaches the position of the branching claw 20e, the conveyance of the paper P is temporarily stopped.
The branch claw 20c opens the sixth paper conveyance path 7a6 and shields the seventh paper conveyance path 7a7 by a claw position switching means (not shown).

  At this time, the branching claw 20b is naturally displaced by an elastic member (spring or the like) disposed on a branching claw holding shaft (not shown) so as to shield the fourth paper conveyance path 7a4.

  Thereafter, the reverse conveyance roller 18 rotates in the reverse direction to re-convey the paper P, and the conveyed paper P passes through the sixth paper conveyance path 7a6 from the rear end side where it stays at the position of the branching claw 20e. The paper is discharged to the paper discharge tray 9 through the paper discharge roller 17.

(Discharge using the double-sided printing method)
When double-sided printing is performed in the image forming apparatus 1A, the first claw printing (front surface printing) of the paper P is finished, and immediately before the paper P that has passed the fixing unit 6 passes the transport roller 16, the branch claw 20a is The claw position switching means (not shown) (solenoid or the like) opens the fourth paper conveyance path 7a4 and shields the third paper conveyance path 7a3.

  Further, the branching claw 20c opens the seventh paper conveyance path 7a7 and shields the fifth paper conveyance path 7a5 by a claw position switching means (not shown). Further, the branch claw 20d opens the sixth paper transport path 7a6 by a claw position switching means (not shown).

  The sheet P to be conveyed is navigated by the branch claw 20a at the leading end thereof, passes through the fourth sheet conveyance path 7a4, and the branch claw 20b is moved by the waist (material strength) and the conveyance force at the front end of the sheet P. After the movement, it is navigated to the branching claw 20c and guided to the seventh paper transport path 7a7 and the sixth paper transport path 7a6.

  When the trailing edge of the sheet P reaches the sixth sheet conveyance path 7a6, the conveyance of the sheet P is temporarily stopped (completion of the first surface switchback). Thereafter, when the branching claw 20d shields the seventh paper conveyance path 7a7 by a claw position switching means (not shown) and the conveyance path to the branching claw 20e is opened, the switchback roller 19 rotates reversely, so Transport is performed.

  The transported paper P passes through the fifth paper transport path 7a5 from the rear end side where it stays at the position of the sixth paper transport path 7a6 via the branching claw 20e, and in the printing process (transfer process in the transfer mechanism). It is conveyed to the registration roller 15 arranged immediately before.

  Thereafter, the second side printing (back side printing) of the paper P is completed, and the paper P that has passed through the fixing unit 6 is subjected to the same processing as described above (single-sided printing and face-up discharge), and the paper discharge tray 9 To be discharged.

Next, the sheet conveyance detection device 170 of the image forming apparatus according to the present embodiment will be described in detail with reference to the drawings.
FIG. 5 is a schematic diagram showing an example of installation of a paper detection sensor constituting the paper conveyance detection device of the image forming apparatus according to the present embodiment, FIG. 6 is a block diagram showing the configuration of the paper detection sensor, and FIG. It is explanatory drawing which shows the electric potential according to the signal reception state by the receiving part of a detection sensor.

  As shown in FIG. 5, the sheet conveyance detection device 170 of the image forming apparatus 1 </ b> A according to the present embodiment includes a sheet detection sensor 171 for detecting the sheet P passing through the sheet conveyance path 7 a, and indicates the conveyance state of the sheet P. By detecting this, it is detected whether or not the paper P is normally conveyed.

  In the present embodiment, the sheet detection sensor 171 includes the conveyance roller 15a on the upstream side in the sheet conveyance direction of the image forming unit 14 on the sheet conveyance path 7a (the position A in the drawing) and the sheet feeding tray 8 side. Are disposed at two locations on the downstream side (B position in the figure) of the conveyance roller 8c of the sheet conveyance section 59 from the sheet conveyance path 7a toward the sheet conveyance path 7a.

  The paper detection sensor 171 includes a transmission unit 171a and a reception unit 171b and employs an ultrasonic detection sensor that detects by ultrasonic waves, and detects the paper P passing between the transmission unit 171a and the reception unit 171b. It is like that.

  As shown in FIG. 6, the paper conveyance detection device 170 is provided with a transmission circuit 171 a 1 that transmits ultrasonic waves and an amplification circuit 171 a 2 that amplifies the ultrasonic waves on the transmission unit 171 a side of the paper detection sensor 171. On the unit 171b side, a resonance circuit 171b1 for resonating the received ultrasonic wave and an amplification circuit 171b2 for amplifying the ultrasonic wave are provided, and an analog signal obtained by the amplified ultrasonic wave is converted into a digital signal by the A / D circuit 171b3. And the CPU 54 performs arithmetic processing based on the digital signal to determine the transport state of the fed paper P.

  As shown in FIG. 7, the signals (potentials) received by the receiving unit 171b are, for example, a signal reception such as a potential E1 before paper passing, a potential E2 when paper passing is detected, and a potential E3 when double feeding is detected. The potential level changes greatly depending on the state. By detecting this potential level, the sheet conveyance detecting device 170 is configured to determine whether or not the sheet P has passed, deformation of the sheet P, and double feeding (multiple sheet conveyance). That is, the paper transport detection device 170 has a paper double feed detection function 175 (see FIG. 8).

  Further, the paper transport detection device 170 can detect the passage of the leading end portion and the trailing end portion of the paper P according to the reception state of the signal when the paper P passes through the paper detection sensor 171. That is, the sheet leading edge detecting function 173 and the sheet trailing edge detecting function 174 are provided.

  In the present embodiment, by using an ultrasonic sensor as the paper detection sensor 171, the directivity is widened without being affected by the paper quality such as the thickness and color of the paper P, and stable detection can be performed without contact.

Next, a control system of the image forming apparatus 1A according to the present embodiment will be described with reference to the drawings.
FIG. 8 is a block diagram showing the configuration of the electric control unit of the image forming apparatus according to the present embodiment.
As shown in FIG. 8, the image forming apparatus 1 </ b> A according to the present embodiment stores image reading processing, image processing, image forming processing, paper P conveyance processing, and the like in a ROM (Read Only Memory) 55 in advance. A central processing unit (CPU) 54 executes processing using temporary storage means such as a RAM (Random access Memory) 56 according to a program.
Note that storage means such as an HDD (hard disk drive) can be used in place of the ROM 55 and the RAM 56.

  In the image forming apparatus 1A, document image information (document image data) read by the scanner unit 22 or document image information transmitted from each terminal device connected to a communication network (not shown) is transmitted via the communication processing unit 58. Are input to the image processing unit 57.

  The image processing unit 57 processes the document image information stored in the storage unit such as the RAM 56 into a print image suitable for printing (image formation on paper) by the above program.

The image information for printing is input to the image forming unit 14.
Image forming section 14, paper transport section (various detection / control of paper in the paper transport path 7a, etc.) 59, fixing unit 6, paper discharge processing section (various detection / control of paper in the paper discharge roller 17) .) 60 is interlocked with each drive control unit 62.

The sheet conveyed by the sheet conveying unit 59 is subjected to a printing process (image information printing process in the image forming unit 14), and then a fixing process (fixing unit 6) for the printed sheet. The paper is discharged to the paper discharge tray 9.
Note that detection signals from a pre-registration detection switch 596, a fixing detection switch (not shown), and a paper discharge detection switch are input to the paper transport unit 59.

  The pre-registration detection switch 596 is a switch that detects whether or not a sheet has reached the registration roller 15. The fixing detection switch is a switch that detects whether or not a sheet has reached the fixing unit 6. The paper discharge detection switch is a switch that detects whether or not the paper is discharged.

  In addition, the conveyance state of the paper P conveyed by the paper conveyance unit 59 is detected by the paper detection sensor 171.

  In the present embodiment, the paper conveyance detection device 170 including the paper detection sensor 171 as one component is based on a signal output from the paper detection sensor 171 and a program stored in the ROM 55, and a paper jam detection function provided in the CPU 54. (Function for detecting whether or not a paper jam has occurred) When paper jam of paper P is detected by 172 or when double feed of paper P is detected by paper double feed detection function 175, transport of paper P is detected. Is temporarily stopped.

  Further, the paper conveyance detection device 170 is arranged on the paper conveyance path by the paper leading edge detection function 173 and the paper trailing edge detection function 174 provided in the CPU 54 based on the output signal of the paper detection sensor 171 and the program stored in the ROM 55. The leading end and the trailing end of the conveyed paper P are detected.

The image forming apparatus 1 </ b> A is provided with an operating condition setting unit 77.
The operation condition setting unit 77 is configured to perform image formation or conveyance conditions of the image forming apparatus 1A according to an image formation request set by the user using the operation switches 76 or an image formation condition such as the type of recording medium (paper). The operation conditions are set.

  The image forming apparatus 1 </ b> A is a driving actuator such as a reading unit (scanner unit 22), a sheet conveying unit 59, an image forming unit 14, a fixing unit 6, and a paper discharge processing unit 60 according to the set operating conditions. Operations of a certain document reading drive unit 64, paper transport drive unit 66, print processing drive unit 68, fixing drive unit 70, and paper discharge drive unit 72, that is, operations synchronized in accordance with commands of the CPU 54 based on a program stored in the ROM 55. The control is performed by the drive control unit 62.

The document reading drive unit 64 is a drive actuator for the scanner unit 22.
The paper transport drive unit 66 is a motor for driving the paper transport unit 59, specifically, the paper pickup roller 8a and the registration roller 15 on the paper transport path 7a.
The print processing drive unit 68 is a drive motor for the photosensitive drum 3.
The fixing driving unit 70 is a driving motor for the heating roller 6 a and the pressure roller 6 b of the fixing unit 6.

The paper discharge driving unit 72 is a driving motor such as a paper discharge roller 17.
The drive motors of these drive units can be configured through a power transmission mechanism as appropriate using the same or different motors as drive sources.

  Further, the image forming apparatus 1A includes, as an optional configuration 74, a post-processing device (staples, punches, a multi-stage discharge tray, a shifter, etc.), an automatic document reading device (automatic document processing device 1A2, etc.), a large-capacity paper feed cassette. 81, etc. can be arranged, and the optional configuration 74 has the control unit 74a in each optional configuration 74 separately from the control unit of the image forming apparatus 1A, and adjusts the timing with the communication processing unit 58. Is configured to synchronize.

  The recording medium detection unit 78 detects that the leading edge of the paper reaches the fixing unit 6 or the carry-out unit.

  Specifically, the recording medium detecting unit 78 includes a conveyance time measuring unit 79a that measures the conveyance time of the sheet after the sheet is sent out from the registration roller 15 that introduces the sheet at the entrance of the sheet conveyance path 7a, and the registration roller. 15 includes a conveyance timing detection unit 79b that detects the conveyance timing of the sheet in the sheet conveyance path 7a based on the distance from the fixing unit 6 to be controlled and the discharge roller 17 and the conveyance speed of the sheet.

  In the present embodiment, the recording medium detection unit 78 is based on the conveyance timing of the recording medium detected by the conveyance timing detection unit 79b when the sheet reaches (enters) the fixing unit 6 and the discharge roller 17 respectively. I try to detect it.

Next, detection of the conveyance state of the paper P by the paper conveyance detection device 170 according to the present embodiment will be described in detail with reference to the drawings.
FIG. 9 is an explanatory diagram illustrating an example of paper jam detection by the paper conveyance detection device of the image forming apparatus according to the present embodiment. FIG. 9A illustrates a paper conveyance failure caused by the conveyance roller at position A in FIG. FIG. 6B is an explanatory diagram illustrating a state in which a conveyance failure of a sheet has occurred in the conveyance roller at position B in FIG. 5.

  In the image forming apparatus 1A, as shown in FIG. 3, the paper P is transported on a plurality of paper transport paths. When a conveyance failure occurs on the sheet conveyance path in such a sheet conveyance state, a conveyance roller on the upstream side in the sheet conveyance direction from the sheet P on which the conveyance failure has occurred, for example, a conveyance roller 15a illustrated in FIGS. 9A and 9B. , 8c is stopped.

  When the trailing edge of the sheet P is returned to the direction of the conveying rollers 15a and 8c, that is, the upstream side in the sheet conveying direction by a conveying roller on the downstream side in the sheet conveying direction (not shown), the sheet P is formed in an S-shape or The paper is bent into a Z shape and a paper jam occurs. At this time, the paper P apparently has three layers.

  By disposing the paper detection sensor 171 in the vicinity of the transport rollers 15a and 8c, the paper P is in a multi-layer state in the same manner as when the paper P that has become jammed is bent into an S shape or a Z shape and the paper is double-fed. Is detected by the ultrasonic sensor, and the paper P is easily and instantaneously jammed (conveyed) by discriminating the state of the first layer and the third layer from the output waveform of the ultrasonic sensor. It is possible to determine (detect) whether or not a failure has occurred.

  With the configuration as described above, according to the present embodiment, the paper P is S-shaped or Z-shaped by installing the paper detection sensor 171 using a non-contact ultrasonic sensor instead of the conventional microswitch. Even if it is in the shape of a letter and floats on the paper transport path, it is possible to determine the paper state at that time, so it is possible to easily detect the paper transport state, jamming due to double feeding or overlapping of paper Can be reliably detected.

  In the conventional method using a mechanical micro switch (actuator), when a jam occurs in the paper as described above, the paper feed sensor detects that the paper has passed, and then passes the paper to the paper conveyance path. Since it was determined whether or not a paper jam occurred when a predetermined time elapses until it is detected that a paper has passed by a certain paper ejection sensor, the presence or absence of the paper jam actually occurs. Although it is difficult to notify the user, according to the present embodiment, it is possible to easily determine (detect) whether or not a jam (conveyance failure) of the paper P has occurred.

  Further, in the conventional method, when the paper is bent into an S-shape or Z-shape and is lifted from a micro switch provided on the paper conveyance path, the paper is not detected because the paper does not contact the micro switch (actuator). Although there was a problem, according to the present embodiment, the paper detection sensor 171 is arranged away from the paper and detects it in a non-contact manner, so that the above problem can be solved.

Further, by developing the present embodiment, the paper detection sensor 171 is installed in place of the contact type microswitch that has been conventionally installed, thereby increasing the number of sensors and the number of CPU ports for inputting sensor signals. It is possible to replace the sensor easily.
With this configuration, since the sheet detection sensor 171 detects the sheet in a non-contact manner, the sheet can be reliably detected without hindering the conveyance of the sheet as compared with the conventional contact type microswitch. it can.

  In this embodiment, the paper detection sensors 171 are arranged at a plurality of locations upstream of the image forming unit 14 in the paper conveyance direction. However, the present invention limits the installation location and the number of paper detection sensors 171. Instead, it may be appropriately arranged in place according to the configuration of the image forming apparatus.

  For example, the present invention can be appropriately applied to a conveyance path of a conveyance object such as a recording paper such as a document reading apparatus, an image recording apparatus, a post-processing apparatus, or the like. Hereinafter, other embodiments according to the present invention will be described.

  In the first exemplary embodiment, as illustrated in FIG. 10, a sheet detection sensor 171 is provided in the automatic document processing apparatus 100 </ b> A <b> 2 in the image forming apparatus 100.

  FIG. 10 is an explanatory diagram showing a schematic configuration of an automatic document processing apparatus constituting the image forming apparatus of this embodiment. Note that the configuration of the image forming apparatus 100 in the present embodiment has substantially the same configuration as that of the image forming apparatus 1A according to the above-described embodiment, and components having the same configuration are denoted by the same reference numerals. 1 shall be omitted, and the overall configuration of the apparatus shall be referred to FIG.

  The automatic document processing apparatus 100 A 2 is installed on the upper part of the apparatus main body 100 A 1, a document tray 111 is disposed on the upper side of the processing apparatus main body 110, and a paper discharge tray 112 is disposed below the document tray 111.

  Inside the automatic document processing apparatus 100A2, a document conveyance path 113 is configured so that the document G supplied from the document tray 111 is discharged from the discharge tray 112 through a predetermined path. A paper feed roller 114, a transport roller 115, and a paper discharge roller 116 are arranged along the document transport path 113 from the upstream side in the document transport direction.

  Between the paper feed roller 114 and the transport roller 115 on the document transport path 113, a paper detection sensor 171 constituting a paper transport detection device (not shown) is placed between the transmitter 171a and the receiver 171b. It is arranged to pass. An ultrasonic sensor is employed as the paper detection sensor 171.

  The original G placed on the original tray 111 is introduced into the processing apparatus main body 110 one by one along the original conveyance path 113 by the paper feed roller 114, and reversely conveyed inside the apparatus via the conveyance roller 115. The paper is discharged onto a paper discharge tray 112 by a paper discharge roller 116. Thus, during the process of transporting the document, the image information of the document G is automatically read.

  In this embodiment, the document G fed (conveyed) from the document tray 111 is easily bent into an S-shape or a Z-shape between the paper feed roller 114 and the transport roller 115, and therefore the document on the paper feed roller 114. A paper detection sensor 171 is installed on the downstream side in the transport direction and on the upstream side of the transport roller 115.

  For the configurations and operations of the paper conveyance detection device and the paper detection sensor 171, refer to the description and drawings of the paper conveyance detection device 170 according to the above-described embodiment.

  Since it is configured as described above, according to the present embodiment, the paper detection sensor 171 is disposed in the document conveyance path 113 of the automatic document processing apparatus 100A2, so that the document G such as an important document causes a paper jam. Since the jam can be detected instantaneously, the operation of the apparatus can be stopped instantaneously, damage to the original G can be minimized, and the original can be easily taken out.

  In the second exemplary embodiment, as illustrated in FIG. 11, a sheet detection sensor 171 is provided in the sheet conveyance path 7 a in the vicinity of the transfer mechanism 210 of the image forming unit 214 in the image forming apparatus 200.

FIG. 11 is a schematic diagram illustrating a configuration in the vicinity of the image forming unit of the image forming apparatus according to the present exemplary embodiment.
In the figure, reference numerals 214a, 214b, and 214c denote conveyance rollers, and 214d denotes a registration sensor.

  The configuration of the image forming apparatus 200 in the present embodiment has substantially the same configuration as that of the image forming apparatus 1A according to the above-described embodiment, and the same components are denoted by the same reference numerals. 1 shall be omitted, and the overall configuration of the apparatus shall be referred to FIG.

  A sheet detection sensor 171 constituting a sheet conveyance detection device (not shown) is disposed between the transmission unit 171a and the reception unit 171b on the downstream side in the sheet conveyance direction from the conveyance roller 214c on the sheet conveyance path 7a near the image forming unit 214. The paper P is arranged so as to pass therethrough. An ultrasonic sensor is employed as the paper detection sensor 171.

  In this embodiment, the sheet P conveyed to the transfer mechanism 210 of the image forming unit 214 is easily bent into an S shape or a Z shape when passing through the conveying roller 214c and the photosensitive drum 3, and therefore the sheet conveying direction. A paper detection sensor 171 is installed on the upstream side.

In the image forming unit 214, since a high voltage is applied to the transfer mechanism 210, it is necessary to always ensure safety.
Therefore, according to the present embodiment, by providing the paper detection sensor 171 on the paper conveyance path 7a passing through the transfer mechanism 210, when the paper P is jammed, it can be instantaneously detected by the ultrasonic sensor. The operation of the apparatus can be stopped instantaneously to ensure the safety of the user.

  In the third exemplary embodiment, as illustrated in FIG. 12, a sheet detection sensor 171 is provided in the sheet conveyance path 7 a near the fixing unit 306 in the image forming apparatus 300.

FIG. 12 is a schematic diagram illustrating a configuration in the vicinity of the fixing unit of the image forming apparatus according to the present exemplary embodiment.
In the drawing, reference numerals 316a, 316b, and 316c denote conveyance rollers, 306a denotes a heating roller, and 306b denotes a pressure roller.

  Note that the configuration of the image forming apparatus 300 in this embodiment has substantially the same configuration as that of the image forming apparatus 1A according to the above-described embodiment, and components having the same configuration are denoted by the same reference numerals. 1 shall be omitted, and the overall configuration of the apparatus shall be referred to FIG.

  In the paper conveyance path 7a near the fixing unit 306, a paper detection sensor 171 that constitutes a paper conveyance detection device (not shown) is disposed further upstream of the conveyance roller 316a upstream of the fixing unit 306 in the paper conveyance direction. And the receiving unit 171b are arranged so that the paper P passes between them. An ultrasonic sensor is employed as the paper detection sensor 171.

  In this embodiment, the sheet P conveyed to the fixing unit 306 is easily bent into an S shape or a Z shape near the conveyance roller 316a due to the heat effect of the heating roller 306a or the pressure applied by the pressure roller 306b. A paper detection sensor 171 is installed upstream of the paper conveyance direction.

  In the fixing unit 306, since the periphery is heated by the heat source 614 of the heating roller 306a, the sheet detection sensor 171 is provided on the sheet conveyance path 7a in the vicinity of the fixing unit 306 as in this embodiment, so that the sheet When P causes a paper jam, it can be detected instantaneously by the ultrasonic sensor, so that the operation of the apparatus can be stopped instantaneously to ensure the safety of the user.

  In the fourth embodiment, as shown in FIG. 13, in the image forming apparatus 400, a sheet detection sensor 171 is provided in the sheet conveyance path 407 inside the continuous post-processing apparatus 401.

FIG. 13 is an explanatory diagram showing the overall configuration of the image forming apparatus 400 of this embodiment.
Note that the configuration of the image forming apparatus 400 in the present embodiment has substantially the same configuration as that of the image forming apparatus 1A according to the above-described embodiment, and components having the same configuration are denoted by the same reference numerals. 1 shall be omitted, and the overall configuration of the apparatus shall be referred to FIG.

  In the image forming apparatus 400, an automatic document processing apparatus 401A2 is mounted on the upper part of the apparatus main body 401A1, and a post-processing apparatus 401 is connected to one side of the apparatus main body 401A1.

  The post-processing device 401 has a desired paper discharge method for the paper P conveyed (discharged) from the apparatus main body 401A1, for example, a sorting method in which a plurality of output papers are arranged in page order and discharged, and a plurality of output papers Are ejected onto a paper ejection tray 409 by a stacking system that ejects the papers for each page, and post-processing steps such as bookbinding, stapling, and punching are performed.

The paper transport path 407 configured inside the post-processing apparatus 401 is configured to be continuous with the paper discharge side of the paper transport path 7a configured inside the apparatus main body 401A1.
Reference numeral 407a denotes a paper introduction unit, and 416a and 416b denote conveyance rollers for conveying the introduced paper P, respectively.

  The sheet conveyance path 407 is configured to convey the sheet P introduced from the apparatus main body 401A1 substantially horizontally by the conveyance roller 416a and then to change the direction downward in the figure via the conveyance roller 416b.

  A sheet detection sensor 171 constituting a sheet conveyance detection device (not shown) is disposed between the transmission unit 171a and the reception unit 171b on the upstream side of the conveyance roller 416a of the sheet conveyance path 407 in the vicinity of the sheet introduction unit 407a in the sheet conveyance direction. The paper P is arranged so as to pass therethrough. An ultrasonic sensor is employed as the paper detection sensor 171.

  In this embodiment, the sheet P conveyed from the apparatus main body 401A1 to the inside of the post-processing apparatus 401 is easily bent into an S shape or a Z shape by the conveyance rollers 416a and 416b. A sensor 171 is installed.

  With the configuration as described above, according to this embodiment, the sheet detection sensor 171 is provided in the sheet conveyance path 407 of the post-processing apparatus 401, so that ultrasonic waves are generated when the introduced sheet P causes a paper jam. Since it can be detected instantaneously by the sensor, the operation of the apparatus can be stopped instantaneously and the paper P can be taken out before the post-processing steps such as bookbinding, stapling, punching, etc., and a useless recovery step can be eliminated.

  Note that the present invention is not limited to the image forming apparatus described in the above-described embodiments and examples, and an image having another configuration having a sheet conveyance path as long as it has a configuration for conveying a sheet. The present invention can be applied to various apparatuses related to forming apparatuses and paper conveyance.

1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a partial detail view showing a configuration of an apparatus main body of the image forming apparatus. FIG. 4 is an explanatory diagram illustrating a configuration of a sheet conveyance path of the image forming apparatus. FIG. 4 is a partial detail view showing a configuration of a branched paper conveyance path that constitutes the paper conveyance path and a branch claw that communicates them. FIG. 2 is a schematic diagram illustrating an example of installation of a paper detection sensor that constitutes a paper conveyance detection device of the image forming apparatus. It is a block diagram which shows the structure of the said paper detection sensor. It is explanatory drawing which shows the electric potential according to the signal reception state by the receiving part of the said paper detection sensor. 2 is a block diagram illustrating a configuration of an electric control unit of the image forming apparatus. FIG. FIG. 6 is an explanatory diagram illustrating an example of paper jam detection by a paper conveyance detection device of the image forming apparatus, where (a) is an explanatory diagram illustrating a state in which a conveyance failure of a sheet has occurred in a conveyance roller at position A in FIG. FIG. 6B is an explanatory diagram illustrating a state in which a paper conveyance failure has occurred in the conveyance roller at position B in FIG. 5. 1 is a schematic diagram of Embodiment 1 illustrating an example of installation of a paper detection sensor that constitutes a paper conveyance detection device of an image forming apparatus according to the present invention. FIG. 10 is a schematic diagram of Example 2 illustrating an example of installation of the paper detection sensor. FIG. 10 is a schematic diagram of Example 3 illustrating an example of installation of the paper detection sensor. FIG. 10 is a schematic diagram of Example 4 illustrating an example of installation of the paper detection sensor.

Explanation of symbols

1A, 200, 100, 300, 400 Image forming apparatus 1A1, 100A1, 401A1 Apparatus main body 1A2, 100A2, 401A2 Automatic document processing apparatus 3 Photosensitive drum 6,306 Fixing unit 7 Paper conveying apparatus (conveying means)
7a 407 paper transport path (transport path)
8b, 8c Conveying roller 10, 210 Transfer mechanism 14, 214 Image forming unit 15a Conveying roller 59 Paper conveying unit (conveying means)
113 Document transport path 114 Paper feed roller 115 Transport roller 116 Paper discharge roller 170 Paper transport detection device (transport detection means)
171 Paper detection sensor (transmission type sensor)
171a Transmission unit 171a1 Transmission circuit 171a2 Amplification circuit 171b Reception unit 171b1 Resonance circuit 171b2 Amplification circuit 171b3 A / D circuit 172 Paper jam detection function 173 Paper leading edge detection function 175 Paper trailing edge detection function 175 Double feed detection function 316a Carrying roller 401 Post processing Device G Document (conveyed material)
P paper (conveyance)

Claims (8)

In an image forming apparatus comprising: a conveying unit that conveys a document or a recording medium as a conveyed item; and a conveyance detecting unit that detects a conveyed item conveyed by the conveying unit.
The transport detection means is disposed on a transport path through which the transported object is transported, and has a paper jam detection function for detecting whether the transported object is normally transported by detecting a transport state of the transported object. An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein a transmissive sensor using ultrasonic waves is used as a configuration of the conveyance detection unit.   The image forming apparatus according to claim 1, wherein the paper jam detection function detects that at least a part of the conveyed product is in an S shape or a Z shape.   The said conveyance detection means has a front-end | tip detection function which detects the front-end | tip of the said conveyed product, and a rear end detection function which detects a rear end, The one of Claim 1 thru | or 3 characterized by the above-mentioned. Image forming apparatus.   5. The image forming apparatus according to claim 1, wherein the transport detection unit has a double feed detection function of detecting that the transported object is double fed. The image forming apparatus includes an automatic document reading device that automatically conveys a document and reads image information of the document,
6. The image according to claim 1, wherein the conveyance detection unit is disposed upstream of an image reading unit provided in the automatic document reading apparatus in a document conveyance direction. Forming equipment. The image forming apparatus includes an electrostatic latent image carrier on which a developer image is formed by a developer, a conveyance unit that conveys a recording medium along the surface of the electrostatic latent image carrier, and the electrostatic latent image. A transfer means for transferring the developer image on the surface of the carrier to a recording medium; and a fixing means for fixing the developer image transferred on the recording medium to the recording medium, the surface of the electrostatic latent image carrier An image forming apparatus configured to perform image output by transferring the developer image formed on the recording medium,
7. The conveyance detection unit according to claim 1, wherein the conveyance detection unit is arranged at least at a position upstream of the transfer unit in the recording medium conveyance direction or upstream of the fixing unit in the recording medium conveyance direction. The image forming apparatus according to one item. The image forming apparatus includes a post-processing device that performs a discharge process of a recording medium that is discharged after image formation,
The image according to any one of claims 1 to 7, wherein the conveyance detection unit is disposed upstream of a recording medium conveyance path formed in the post-processing apparatus in a recording medium conveyance direction. Forming equipment.

Images