JP4553807B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus controlled to transfer a developer image formed on the surface of the electrostatic latent image carrier by an electrophotographic method onto a recording medium by a transfer electric field. About.

In recent years, development of electrophotographic image forming apparatuses that perform high-speed printing processing has progressed.
For example, in an electrophotographic image forming apparatus, the number of sheets to be printed was 40 to 60 sheets / minute for standard paper (A4 horizontal transport) until several years ago, but in recent years it has been 100 to 120 sheets / minute. As a result, the processing speed of the image forming apparatus is increased (see Patent Document 1).

  In the development of such an image forming apparatus, it is necessary to avoid paper conveyance troubles (JAM, etc.), but it is not necessarily the case that a complete countermeasure is taken. The reason is that when a plurality of types of paper sizes are transported under the same conditions, the paper thickness and form are different depending on the specifications of each country even if the paper size is the same.

When continuous printing is performed in the high-speed image forming apparatus, printing processing, fixing processing, and the like are simultaneously performed while a plurality of sheets are being conveyed, depending on the length of the sheet conveying path.
For example, in an image forming apparatus of 120 sheets / minute, it is necessary to perform each process (printing process, etc.) for each sheet within 0.5 seconds, and a plurality of sheets stay in the apparatus. In this state, if a trouble occurs in paper conveyance, the paper stays in each part, so it is necessary to perform processing for removing the paper in each part.

At this time, when the image recording apparatus judges the trouble and stops the operation, the drive source and each rotating body generally do not stop simultaneously with the stop, depending on the driving method. At present, it is stopped after a slight rotation.
Japanese Patent Laid-Open No. 11-73067

  In contrast to the current situation, a plurality of transport rollers, fixing rollers, and the like arranged on the paper transport path have a small mass, so there is little influence even if there is inertia, but with a photosensitive drum as an electrostatic latent image carrier, Since it has a certain mass, even if the drive is stopped, rotation due to inertia may cause problems such as scratches on the surface of the photosensitive drum or toner scattering.

  For example, if an emergency stop is performed when the paper being transported is in front of the photosensitive drum, the paper stops after rotating with inertia in a state where there is a charge and a toner image (image information) on the photosensitive drum. To do. In the transfer unit (for example, in the case of a transfer belt system), the transfer electric field is turned off at the same timing as the emergency stop, so that the conveyed paper is not attracted to and transferred to the transfer belt, and the electric field generated on the photosensitive drum The photosensitive drum is adsorbed.

  On the other hand, the sheet peeling claw, which is a recording medium peeling member disposed on the outer periphery of the photosensitive drum, is turned off at the same timing as the emergency stop and is separated from the photosensitive drum, as with the transfer electric field. The sheet adsorbed on the photosensitive drum is conveyed to the cleaning unit and is stopped by the cleaning blade as a cleaning member.

At this time, the surface of the photosensitive drum is scratched by rubbing with the paper and the cleaning blade, thereby causing a decrease in print quality and deterioration of the photosensitive drum.
That is, the surface of the photosensitive drum is repeatedly rubbed by the paper and the cleaning blade, thereby causing a problem that the photosensitive layer formed on the surface is damaged and a leak phenomenon occurs.

  Further, there is a problem that the cleaning blade is damaged by the paper stuck to the photosensitive drum, and the toner formed on the photosensitive drum is scattered in the apparatus.

  The present invention has been made in view of the above-described conventional problems, and prevents the transfer medium from sticking to the electrostatic latent image carrier when an emergency stop is performed from the normal operation state of the image forming apparatus. To provide an image forming apparatus capable of reducing the load on the cleaning member, reducing the scattering of the developer into the apparatus, improving the maintainability, and extending the life of the electrostatic latent image carrier. It is intended.

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, wherein an electrostatic latent image carrier on which a developer image is formed by a developer, charging means for charging a surface of the electrostatic latent image carrier, and the electrostatic latent image An exposure means for forming an electrostatic latent image on the surface of the carrier, a developing means for developing the electrostatic latent image formed on the surface of the electrostatic latent image carrier with a developer, and a recording medium for the static medium. A recording medium conveying means for conveying 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 static before the transfer step by the transfer means. A pre-transfer charge eliminating means for removing the electric potential charged on the electrostatic latent image carrier, a recording medium peeling member for peeling the recording medium attached to the electrostatic latent image carrier, and the recording medium peeling member And a peeling member driving means for contacting and separating the latent image carrier. In control image forming apparatus arranged to transfer onto a recording medium by the transfer electric field the developer image formed on the surface of the image bearing member,
At the timing when trouble occurs during the printing process during operation , the energization to the drive means other than the pre-transfer charge eliminating means is urgently stopped, and after that timing , the energization to the pre-transfer charge eliminating means is stopped. With stop operation control function,
The energization stop timing to the pre-transfer charge eliminating means is the time from when the energization to the driving means of the electrostatic latent image carrier is stopped until the rotation due to inertia of the electrostatic latent image carrier is stopped. After or after a time has elapsed until the recording medium to be conveyed reaches the recording medium peeling member from a registration roller arranged on the upstream side in the recording medium conveyance direction of the electrostatic latent image carrier,
Whether or not to restart the printing when the trouble and the paper removal message are displayed on the display section of the apparatus after the energization of the pre-transfer grading means is stopped and the trouble is solved and the paper being transported is removed It is an image forming apparatus characterized by determining whether or not .

  An emergency stop is when a recording medium is jammed in the recording medium conveyance path for conveying the recording medium, causing a conveyance trouble, or when a recording medium sticks to the electrostatic latent image carrier and a conveyance trouble occurs. Thus, it is assumed that the image forming apparatus or a control device that controls the image forming apparatus automatically or manually stops the printing process, the image forming process, the paper transporting process, and the like.

  The image forming apparatus described in claim 2 is characterized in that, in addition to the configuration described in claim 1, a static elimination lamp or a static elimination electrode is used in the configuration of the pre-transfer static elimination means.

  According to a third aspect of the present invention, in addition to the configuration described in the first or second aspect, at least the driving source of the electrostatic latent image carrier and the recording are provided as driving means for stopping energization at the time of the emergency stop. It is characterized by including a drive source for the medium conveying means.

  According to the first aspect of the present invention, in the image forming apparatus controlled to transfer the developer image formed on the surface of the latent electrostatic image bearing member onto the recording medium by a transfer electric field by electrophotography. And a stop operation control function for stopping energization to the pre-transfer charge eliminating means after stopping energization to the drive means other than the pre-transfer charge eliminating means when an emergency stop is performed during the driving operation. As a result, even when the electrostatic latent image carrier continues to rotate due to inertia when the image forming apparatus is urgently stopped from the normal operating state, an electric field is generated on the electrostatic latent image carrier by the pre-transfer charge eliminating means. Therefore, the surface potential of the electrostatic latent image carrier is lowered to weaken the adsorption force for adsorbing the recording medium, making it easier to transfer the developer on the electrostatic latent image carrier to the recording medium. Facilitating peeling from the electrostatic latent image carrier Kill.

  This prevents the transfer medium from sticking to the electrostatic latent image carrier during an emergency stop of the apparatus, prevents the cleaning member from being damaged, and suppresses the scattering of the developer in the apparatus. It is possible to prevent the surface of the electrostatic latent image carrier from being damaged by the medium peeling member, thereby improving the maintainability and achieving an excellent effect that the life of the electrostatic latent image carrier can be extended.

Moreover, according to invention of Claims 2-3 , 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 static elimination lamp or a static elimination electrode as the configuration of the pre-transfer neutralization means, the pre-transfer can be performed without contacting the electrostatic latent image carrier with a simple configuration. Can be removed.

  According to the third aspect of the present invention, the drive means for stopping energization at the time of the emergency stop includes at least the drive source of the electrostatic latent image carrier and the drive source of the recording medium transport means. Even after the driving means related to transferring image information to the medium is stopped, the electric potential generated by the pre-transfer charge eliminating means is generated in the electrostatic latent image carrier, so that the surface potential of the electrostatic latent image carrier is lowered. Accordingly, the adsorption force for adsorbing the recording medium can be weakened to facilitate the transfer of the developer on the electrostatic latent image carrier to the recording medium, and the recording medium can be easily separated from the electrostatic latent image carrier. .

According to the first aspect of the present invention, at least the recording medium to be transported is disposed upstream of the electrostatic latent image carrier in the recording medium transporting direction with respect to the timing of stopping energization of the pre-transfer neutralizing unit. After the time until the recording medium peeling member reaches the recording medium peeling member from the registration roller, after the energization is stopped, the recording medium reaches the recording medium peeling member from a state where it is conveyed to the electrostatic latent image carrier. Even if the electrostatic latent image bearing member rotates due to inertia, the electric field generated by the pre-transfer neutralization means is generated on the electrostatic latent image bearing member, so that the surface potential of the electrostatic latent image bearing member is lowered to perform recording. It is possible to weaken the adsorption force for adsorbing the medium to facilitate the transfer of the developer on the electrostatic latent image carrier to the recording medium, and to facilitate the peeling of the recording medium from the electrostatic latent image carrier.

According to the first aspect of the present invention, the timing of stopping energization of the pre-transfer neutralization unit is determined from when the energization to the driving unit of the electrostatic latent image carrier is stopped. After the time until the rotation due to inertia stops has elapsed, after the energization is stopped, the electrostatic latent image is transferred from the state where the recording medium is conveyed to the electrostatic latent image carrier to the recording medium peeling member. Even if the image carrier rotates due to inertia, an electric field is generated in the electrostatic latent image carrier by the pre-transfer neutralization means, so that the surface potential of the electrostatic latent image carrier is lowered to attract the recording medium. It is possible to weaken the attracting force so that the developer on the electrostatic latent image carrier can be easily transferred to the recording medium, and the recording medium can be easily peeled from the electrostatic latent image carrier.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2 are examples of embodiments of 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 an apparatus main body of the image forming apparatus. It is a partial detailed view which shows a structure.

  The image forming apparatus 1A according to the present embodiment outputs and forms image data transmitted from the outside as a monochrome image on a predetermined sheet-like recording sheet (hereinafter referred to as a sheet) serving as a recording medium by an electrophotographic method. Is.

  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 (exposure unit) 1, a developing unit (developing unit) 2, a photosensitive drum (electrostatic latent image carrier) 3, and a charger ( (Charging means) 4, neutralization device (pre-transfer neutralization means) 41, cleaner unit 5, fixing unit 6, paper transport path 7, paper feed tray 8, paper discharge tray 9, transfer mechanism (transfer means) 10, and the like. The apparatus main body 1A1 and the automatic document processing apparatus 1A2 are configured.

  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 charge eliminating device 41, a cleaner unit 5, a fixing unit 6, a paper transport path 7, a paper discharge tray 9, and a transfer mechanism. 10 is disposed, and further below that, a sheet feed tray 8 in which sheets are stored is disposed.

  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 paper peeling claw (recording medium peeling member) 31, the cleaner unit 5, and the electric field generating unit are directed downstream in the rotational direction of the photosensitive drum with reference to the position after the image transfer is completed. The charger 4, the developing device 2, and the charge removal device 41 are arranged in this order.

  The paper 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 (peeling member driving means) 32. The paper peeling claw 31 is in contact with the outer peripheral surface of the photosensitive drum 3 and is attached to the surface of the photosensitive drum 3 when an unfixed toner image on the photosensitive drum 3 is transferred to the paper. Is to peel 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 is driven (not shown) so that the leading edge of the paper supplied from the paper feed tray 8 and the toner image on the photosensitive drum 3 are aligned and conveyed between the photosensitive drum 3 and the transfer belt 103. The operation is controlled by the means and the control means.

The charger 4 is a charging unit 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 the present embodiment, the charger type charger 4 is used, but a contact type roller type or a brush type may be used.

  The static eliminator 41 is a pre-transfer static eliminator for lowering 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 a sheet. It is arranged downstream of the developing device 2 in the rotation direction and below the photosensitive drum 3 and in proximity to the outer peripheral surface thereof.

  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 on the sheet by applying the electric field having the opposite polarity to the electric charge of the electrostatic image from the transfer mechanism 10 onto the sheet to be conveyed. Is transcribed.
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 (1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm in this embodiment). The transfer belt unit is disposed below the photosensitive drum 3 so that the surface of the transfer belt 103 contacts a part of the outer peripheral surface of the photosensitive drum 3. Has been. The transfer belt 103 conveys the paper 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 are in surface contact having a predetermined width (referred to as a transfer nip), so that the sheet is conveyed. The transfer efficiency can be improved.

  Further, on the downstream side of the transfer area of the transfer belt 103 in the paper conveyance direction, a neutralization roller 106 is provided to neutralize the electric field applied to the conveyed paper in the transfer area and smoothly carry it to the next process. 103 is arranged on the back side.

  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 by the transfer mechanism 10 is conveyed to the fixing unit 6 and is pressurized and heated, whereby the unfixed toner is melted and fixed on the paper.

  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 sheet is sandwiched between the heating roller 6a and the pressure roller 6b, and the heating roller 6a is rotated. The toner image transferred onto the paper is melted and fixed by passing between 6a and the pressure roller 6b.

  On the downstream side of the fixing unit 6 in the paper conveyance direction, a conveyance roller 16 for conveying the paper is provided.

  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, in the fixing unit 6, unfixed toner on the conveyed paper is heated to the heating roller 6a in a pressure contact portion (so-called fixing nip portion) 600 between the heating roller 6a and the pressure roller 6b. The unfixed toner is fixed on the paper by a throwing action on the paper 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 half-moon-shaped paper pickup roller 8a is disposed on the upper side of the paper discharge side of the paper feed tray 8 (see FIG. 3).

  The paper pick-up roller 8a picks up the sheets stacked and accommodated in the paper feed tray 8 one by one from the uppermost layer, toward the downstream side (for convenience, the paper flow-out side (cassette side) is upstream and the paper discharge side. ) Is conveyed to the registration roller (also referred to as “idle roller”) 15 side on the sheet conveyance path 7.

  In the image forming apparatus 1A according to the present embodiment, in order to perform high-speed printing processing, a plurality of paper feeds capable of storing 500 to 1500 sheets of standard size sheets in each tray below the image forming unit 14. A 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 size is mainly disposed above the large-capacity paper feed cassette 81. A manual feed tray 82 corresponding to the 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 conveyance path 7 is configured between the photosensitive drum 3 and the paper feed tray 8 described above, and conveys the paper supplied from the paper feed tray 8 to the transfer mechanism 10 one by one. The sheet on which the toner image is transferred from the body 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, the sheet conveyance path formed according to the designated processing mode The paper is conveyed by the branching claw.

Here, the sheet conveyance path 7 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 mainly includes the first sheet conveyance path 7 a 1 from the sheet feed tray 8 to the registration rollers 15, and the fixing unit 6 from the registration rollers 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 with switch It is composed of the eighth sheet conveying path 7a8 leading to Kkurora 19.

  A plurality of sheets P are arranged in the sheet transport path 7 according to the processing mode. In the present 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 7. 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.

  Further, in the paper transport path 7, a plurality of branching claws for selecting the paper transport path according to the selected processing mode and changing the transport path of the paper P 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 7 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.

  Next, a sheet conveyance 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 7.
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 7, 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 1 </ b> A and the printing processing method (single-sided printing, duplex printing). The transport method up to 9 is different.

  Usually, 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 means (not shown) immediately before the paper P that has passed the fixing unit 6 passes the transport roller 16. The fourth paper transport path 7a4 is opened by a solenoid or the like, and the third paper transport path 7a3 is shielded.

  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, a control system of the image forming apparatus 1A according to the present embodiment will be described with reference to FIG.
FIG. 5 is a block diagram showing the configuration of the electric control unit of the image forming apparatus according to this embodiment.
As shown in FIG. 5, 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, image information (original image data) of an original read by the scanner unit (original reading unit) 22 or original image information transmitted from each terminal device connected to a communication network (not shown) The image data is input to the image processing unit 57 via the processing unit 58.

  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 a recording sheet) by the above program.

The image information for printing is input to the image forming unit 14.
Image forming unit 14, paper conveyance unit (various detection / control of paper in the paper conveyance path 7) 59, fixing unit 6, paper discharge processing unit (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 such as a pre-registration detection switch, a fixing detection switch, and a paper discharge detection switch (not shown) are input to the paper conveyance unit 59.

  The pre-registration detection switch is a switch that detects whether or not the 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.

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, recording paper conveyance 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 This is performed under the control of the drive control unit 62.

  In addition to the control function described above, the drive control unit 62 is a stop operation control function for controlling the stop operation of each drive unit (drive means) when an emergency stop is performed during the driving operation of the image forming apparatus 1A. 63.

  The stop operation control function 63 is a function for controlling the energization to the static eliminator 41 after the energization to a drive unit (drive means) other than the static eliminator 41 is stopped.

  In this embodiment, at least a drive source (not shown) of the photosensitive drum 3 as a drive unit that stops energization at the time of an emergency stop, a paper P pickup roller 8a on the paper transport path 7, and a drive motor (not shown) for the registration roller 15. After the energization to (omitted) is stopped, the energization to the static eliminator 410 is stopped.

The document reading drive unit 64 is a drive actuator for the scanner unit 22.
The recording paper conveyance drive unit 66 is a motor for driving the paper conveyance unit 59, specifically, the paper pickup roller 8 a and the registration roller 15 on the above-mentioned paper conveyance path 7.
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 drive unit 72 is a drive motor such as a paper discharge roller 17.
The drive motors of these drive units can be appropriately configured through a power transmission mechanism 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 (stapling, punching, a multi-stage paper 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 detection 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 7, and the registration roller. A conveyance timing detection unit 79b for detecting the conveyance timing of the paper in the paper conveyance path 7 based on the distance from the fixing unit 6 to be controlled and the paper discharge roller 17 and the conveyance speed of the paper.

  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.

Here, the operation timing in the printing process of the image forming apparatus 1A of the present embodiment will be described with reference to a timing chart.
FIG. 6 is a timing chart showing the operation timing of each part of the image forming apparatus according to the present embodiment.

  As shown in FIG. 6, the outline of the operation when the image forming apparatus 1A performs the printing process is as follows: (1) When the power is turned on to the image forming apparatus 1A at the timing T1, at the same time, (2) the fixing unit 6 The heater which is the heat source 614 is turned on.

  When (3) a print request is made at the timing T2 after the lapse of a predetermined time, at the same time, (4) the photosensitive drum 3 starts operating, and (5) the developing device 2 starts operating.

  Then, (3) at time T3 after receiving the print request, (6) the paper P that matches the print request is started to be fed from the paper feed tray 8.

  After that, at a timing T4 after a predetermined time has elapsed, (7) the photosensitive drum 3 is charged by the charger 4. Here, an image forming process is performed in which an electrostatic latent image is formed on the photosensitive drum 3 by laser light, and a toner image is formed by a developer (toner) by the developing device 2.

  Then, at timing T5, (8) after the static elimination device 41 performs static elimination before the transfer of the photosensitive drum 3, (9) at timing T6 (9) for transferring the toner image onto the paper P conveyed from the transfer mechanism 10. Transfer charging is performed, and thereafter, at timing T7, (10) the sheet peeling claw 31 is operated and brought into contact with the photosensitive drum 3 to enable the sheet peeling action.

  At the timing described above, the image forming unit 14 performs operations related to the image forming process on the photosensitive drum 3 and the transfer process of the toner image from the photosensitive drum 3 to the paper P during the normal operation.

Next, in the image forming apparatus 1A according to the present embodiment, an operation in the case where an emergency stop is performed due to a paper conveyance trouble or the like during the printing process will be described in detail with reference to the drawings.
FIG. 7 is a flowchart showing an operation when an emergency stop is performed during the printing process of the image forming apparatus according to the present embodiment. S1, S2,... In the figure indicate each process (step).

The printing process by the image forming apparatus 1A is performed according to the flowchart shown in FIG.
First, when a print request is made from the standby state of the image forming apparatus 1A (step S1), it is determined whether or not input of printing conditions is completed (step S2).

  When the input of the printing conditions is not completed, a display for prompting the condition input is performed on the display unit of the operation unit of the apparatus (step S3), and the process returns to step S2.

When the input of the printing conditions is completed, the printing process is started (step S4).
Thus, the printing process is started, and it is determined whether a trouble has occurred during the printing process (step S5).

  When the printing process is finished without causing any trouble, it is determined whether or not there is the next printing (step S6). If there is the next printing, the process returns to step S4, and the printing process is started again continuously.

  If it is determined in step S5 that a trouble has occurred, an emergency stop is performed based on the stop operation control function 63 (step S7).

Here, the stop operation control based on the stop operation control function 63 in step S7 will be described in detail.
FIG. 8 is a flowchart showing stop operation control during an emergency stop of the image forming apparatus according to the present embodiment.

  As shown in FIG. 8, the operation control by the stop operation control function 63 controls the stop operation of the static eliminator 41 simultaneously with the emergency stop.

  First, in a state where energization of the static eliminator 41 is continued, energization to other drive units including the drive source of the photosensitive drum 3 and the drive source of the transfer mechanism 10 is stopped (step S101).

  Then, after a predetermined time has passed since the emergency stop (step S102), the energization to the static eliminator 41 is stopped, and the application of the electric field to the photosensitive drum 3 is stopped (step S103).

  Here, in the present embodiment, the predetermined time is a time until at least the rotation due to inertia of the photosensitive drum 3 stops after the energization of the driving means of the photosensitive drum 3 is stopped.

  The predetermined time may be a time required for the conveyed paper P to reach the paper peeling claw 31 from the registration roller 15.

(Continuation of emergency stop process)
A trouble message and a message prompting the removal of the paper P staying in the paper P transport path 7 are displayed on the display unit of the operation unit of the apparatus (step S8).

  It is determined whether or not the trouble has been resolved (step S9). If the trouble has been resolved, it is determined whether or not the paper P staying in the paper transport path 7 has been removed (step S10).

  When the trouble is solved and the paper P is removed from the paper transport path 7, it is determined whether or not printing is resumed (step S11). When printing is not resumed, the image forming apparatus 1A enters a standby state.

On the other hand, when the printing is resumed, the display of the operation unit of the apparatus is displayed by pressing the start key (step S12). When the start key is pressed, the process returns to step S4 (proceeds to the circled number 1 in the figure), and the printing process is started again.
As described above, when an emergency stop is performed, the printing process and the operation of each drive unit are controlled based on the stop operation control function 63.

Next, the operation timing based on the stop operation control function 63 at the time of emergency stop in the printing process of the image forming apparatus 1A of the present embodiment will be described with reference to a timing chart.
FIG. 9 is a timing chart showing the operation timing of each part when an emergency stop is performed during the printing process of the image forming apparatus, and FIG. 10 shows the state of paper on the photosensitive drum at the timing of part B in FIG. It is explanatory drawing shown.
In addition, in the operation timing in a figure, the thing similar to the operation timing at the time of the above-mentioned normal driving | operation is attached | subjected, and description is abbreviate | omitted.

  The operation of each unit in the printing process of the image forming apparatus 1A is controlled based on the stop operation control function 63 when an emergency stop is performed.

  In the printing process of the image forming apparatus 1A, as shown in FIG. 9, when the apparatus is in normal operation, the operation timings of the respective components (1) to (10) in the figure are continuously at timings T2 to T7. Done.

  When trouble occurs in the apparatus and an emergency stop occurs, at the same time, the charge removal apparatus 41 that performs charge removal before transfer of the photosensitive drum 3 of (8) of (1) to (10) is excluded at timing T8. Energization to each part is stopped.

  The neutralization device 41 of (8) is controlled to stop the neutralization process on the photosensitive drum 3 by stopping energization at timing T9 after a predetermined time has elapsed.

  In addition, the rotation due to the inertia of the photosensitive drum 3 itself after the energization is stopped is stopped between the timings T8 and T9.

  As described above, according to the present embodiment, when the image forming apparatus 1A is in an emergency stop, the stop operation control function 63 controls each drive unit to stop, as shown in FIG. While the photosensitive drum 3 is rotating, the neutralization process to the photosensitive drum 3 by the static eliminator 41 is continued, so even if the toner image is being transferred to the paper P by the photosensitive drum 3, The toner image can be transferred to the paper P while weakening the suction force that the paper is attracted to the photosensitive drum 3. As a result, the sheet P does not stick to the photosensitive drum 3 and the residual toner can be reduced. Therefore, the toner can be prevented from scattering into the apparatus without imposing a load on the cleaning member.

  Therefore, according to the present embodiment, the paper P can be prevented from sticking to the photosensitive drum 3 with simple control, and the paper can be easily peeled off from the photosensitive drum 3. The maintainability of the periphery of the photosensitive drum 3 and the paper conveyance path 7 can be remarkably improved, and the paper P can be removed without damaging the surface of the photosensitive drum 3, so that the life of the photosensitive drum 3 can be extended. realizable.

  Further, according to the present embodiment, the image forming apparatus 1A is configured to be capable of a plurality of processing modes (copier mode, printer mode, FAX mode), and the configuration of the paper transport path 7 also corresponds to the plurality of processing modes. Since it is configured, when an emergency stop is performed during operation, the same effects as described above can be obtained in any processing mode.

  In the present embodiment, the timing T9 at which the energization to the static eliminator 41 is stopped is the time until the rotation due to the inertia of the photosensitive drum 3 itself stops after the energization to the driving means of the photosensitive drum 3 is stopped. The present invention does not limit the timing for stopping energization to the static eliminator 41.

  For example, as a modification, the timing T9 at which the energization to the static eliminator 41 is stopped may be after the time required for the sheet P conveyed to the transfer mechanism 10 to reach the sheet peeling claw 31 from the registration roller 15. .

  With such a configuration, the potential charged on the photosensitive drum 3 by the charge removal process by the charge removal device 41 can be lowered until the conveyed paper P reaches the paper peeling claw 31 from the registration roller 15. In addition, it is possible to weaken the suction force that attracts the sheet to the photosensitive drum 3 and to transfer the toner image onto the sheet.

  As a result, the paper P does not stick to the photosensitive drum 3 and the residual toner can be reduced, so that the load on the cleaning member can be reduced and the scattering of toner into the apparatus can be reduced.

  Therefore, according to the modification, the sheet conveyed along the photosensitive drum 3 does not enter between the sheet peeling claw 31 and the outer peripheral surface of the photosensitive drum 3 as in the above-described embodiment. Since P can be easily peeled off from the outer peripheral surface of the photosensitive drum 3, the staying paper P can be easily taken out without damaging the surface of the photosensitive drum 3, and maintenance of the periphery of the photosensitive drum 3 and the paper conveyance path 7 can be performed. Property can be remarkably improved.

  Furthermore, as another modified example, the timing T9 at which the energization to the static eliminator 41 is stopped may be after the elapse of time until the rotation of the photosensitive drum 3 due to the inertia of the photosensitive drum 3 stops.

  With this configuration, even when the transfer of the toner image onto the paper P by the photosensitive drum 3 is performed by inertia after the energization is stopped, while the photosensitive drum 3 is rotated by inertia, Since the static eliminator process on the photosensitive drum 3 by the static eliminator 41 is continued, even if the toner image is transferred onto the paper P by the photosensitive drum 3, the adsorption force that attracts the paper to the photosensitive drum 3. And the toner image can be transferred onto the paper P. As a result, the sheet P does not stick to the photosensitive drum 3 and the residual toner can be reduced. Therefore, the toner can be prevented from scattering into the apparatus without imposing a load on the cleaning member.

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 illustrating a configuration of a branched paper conveyance path that constitutes the paper conveyance path and a branching claw that connects the branched paper conveyance paths. 2 is a block diagram illustrating a configuration of an electric control unit of the image forming apparatus. FIG. 3 is a timing chart illustrating operation timings of respective units of the image forming apparatus. 6 is a flowchart illustrating an operation when an emergency stop is performed during a printing process of the image forming apparatus. 6 is a flowchart illustrating stop operation control during an emergency stop of the image forming apparatus. 6 is a timing chart showing the operation timing of each part when an emergency stop is performed during the printing process of the image forming apparatus. FIG. 10 is an explanatory diagram illustrating a state of a sheet on a photosensitive drum at a timing of a part B in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Image forming apparatus 1A1 Apparatus main body 1A2 Automatic document processing apparatus 1 Exposure unit (exposure means)
2 Developer (Developer)
3 Photosensitive drum (electrostatic latent image carrier)
4 Charger (charging means)
7 Paper transport path 7a1 1st paper transport path 7a2 2nd paper transport path 7a3 3rd paper transport path 7a4 4th paper transport path 7a5 5th paper transport path 7a6 6th paper transport path 7a7 7th paper transport path 7a8 8th paper Transport path 10 Transfer mechanism (transfer means)
14 Image forming section 15 Registration roller 20a, 20b, 20c, 20d, 20e Branch claw 31 Paper peeling claw (recording medium peeling member)
32 Solenoid (peeling member driving means)
41 Static eliminator (static means before transfer)
62 drive control unit 63 stop operation control function 101 drive roller 102 driven roller 103 transfer belt (recording medium conveying means)
104 Contact portion 105 Elastic conductive roller T1, T2, T3, T4, T5, T6, T7, T8, T9 Timing P Paper (recording medium)

Claims (3)

An electrostatic latent image carrier on which a developer image is formed by a developer, charging means for charging the surface of the electrostatic latent image carrier, and forming an electrostatic latent image on the surface of the electrostatic latent image carrier Exposing means, developing means for developing the electrostatic latent image formed on the surface of the electrostatic latent image carrier with a developer, and transporting the recording medium along the surface of the electrostatic latent image carrier Recording medium conveying means, transfer means for transferring the developer image on the surface of the electrostatic latent image carrier to a recording medium, and a potential charged on the electrostatic latent image carrier before the transfer step by the transfer means. Pre-transfer charge eliminating means to be removed, a recording medium peeling member for peeling the recording medium stuck to the electrostatic latent image carrier, and a peeling member drive for bringing the recording medium peeling member into and out of contact with the electrostatic latent image carrier And a developer formed on the surface of the electrostatic latent image carrier by electrophotography In control image forming apparatus arranged to transfer onto a recording medium by the transfer electric field,
At the timing when trouble occurs during the printing process during operation , the energization to the drive means other than the pre-transfer charge eliminating means is urgently stopped, and after that timing , the energization to the pre-transfer charge eliminating means is stopped. With stop operation control function,
The energization stop timing to the pre-transfer charge eliminating means is the time from when the energization to the driving means of the electrostatic latent image carrier is stopped until the rotation due to inertia of the electrostatic latent image carrier is stopped. After or after a time has elapsed until the recording medium to be conveyed reaches the recording medium peeling member from a registration roller arranged on the upstream side in the recording medium conveyance direction of the electrostatic latent image carrier,
Whether or not to restart the printing when the trouble and the paper removal message are displayed on the display section of the apparatus after the energization of the pre-transfer grading means is stopped and the trouble is solved and the paper being transported is removed An image forming apparatus characterized by determining whether or not .   The image forming apparatus according to claim 1, wherein the pre-transfer charge removal unit uses a charge removal lamp or a charge removal electrode.   3. The image formation according to claim 1, wherein the driving unit that stops energization at the time of the emergency stop includes at least a driving source of the electrostatic latent image carrier and a driving source of the recording medium conveying unit. apparatus.

Images