JP5186326B2 - Printing device recovery mechanism and paper transport device - Google Patents

Description

  The present invention relates to a recovery mechanism and a recovery method of a printing apparatus having an image forming unit that forms an image on a surface of a sheet transported on a transport path such as an ink jet printer.

  In recent years, image forming apparatuses have been requested to increase the speed of image forming processing. When image forming processing is performed on a large number of sheets, a plurality of sheets are fed from a sheet feeding unit at short intervals. In such an image forming apparatus that performs image forming processing at a high speed, when a failure (jam) occurs in paper conveyance or printing processing in a part of the conveyance path, there is a large number of sheets in the conveyance path. Since the operation is stopped, when removing all the paper in the transport path at the time of this jam release work, the removal work becomes complicated, it takes a long time to work, and it can be used without being affected by jam Waste paper, which is a waste of resources.

Conventionally, as a technology for responding to these problems, when a paper jam occurs in a part of the transport path, the paper in the middle of the printing process in which the printing process is completed on the downstream side in the transport direction of the paper position related to the jam is discharged. Some perform recovery (Patent Document 1).
JP 2002-137849 A

  However, in recent years, printing apparatuses that perform double-sided printing are also widely used, which have a function of automatically reversing printing paper. The structure for this automatic reversal is complicated, and the paper is simply discharged downstream. There are some models that cannot easily recover jams.

  For example, as a function of automatically reversing the paper, there is a method of providing a so-called switchback path in the path for circulating the print paper, and reversing the front and back by switching back the print paper. In the technique disclosed in Patent Document 1 described above, since the paper in the switchback path cannot be completely discharged, the print paper needs to be removed by the user himself, and the switchback mechanism is complicated. The release work is further complicated.

  Accordingly, the present invention has been made in view of the above points, and facilitates the removal of the paper staying in the conveyance path and can prevent the recording head in the image forming unit from being damaged when a paper failure occurs. It is an object of the present invention to provide a recovery mechanism and a recovery method.

In order to solve the above-described problems, the present invention provides a recovery mechanism of a printing apparatus having an image forming unit that forms an image on a surface of a sheet conveyed on a conveyance path, wherein the conveyance path is a sheet feeding unit that supplies the sheet. The normal conveyance path from the path to the paper discharge path to the paper discharge path is branched and connected to the normal conveyance path, the paper is delivered from the normal conveyance path, and the paper is reciprocated by rotating the conveyance mechanism forward and backward. And a reverse path that reverses the front and back of the paper by returning it to the normal transport path, and the reverse path has a paper discharge port near the end of the forward path due to normal rotation, and the transport mechanism until the paper passes through the transport mechanism. by continuing the forward operation of discharging the paper from the discharge port, the reverse path, when a failure is detected in the transport path, the sheet to be located forward in the reversal path, the forward rotation of the conveying mechanism Ri is discharged from the discharge port, the sheet is located in the feed path to the return or normal path in the reverse path, after temporarily stops the conveyance mechanism, it is discharged from the discharge port by the reverse rotation.

  According to such an invention, in an apparatus having a reversing path and capable of double-sided printing by switchback, by providing a discharge port in the reversing path and utilizing the normal rotation operation of the transport mechanism, the stagnating in the reversing path The sheet in the reversing path can be easily removed with a simple configuration.

  In the above invention, it is preferable that the discharge port is a plate-shaped pedestal arranged below a space required for the reciprocation of the paper. In this case, when the sheet is discharged from the discharge port by the forward rotation operation, the sheet can be received from below, and the user can easily remove the sheet.

  In the above invention, the conveyance path includes another discharge path that is branched and connected to the conveyance path and discharges the sheet. The discharge port has a casing portion that surrounds a space required for the reciprocation of the sheet. The upper surface is preferably a cradle for paper discharged from another discharge path. In this case, the upper surface of the casing portion serves as a receiving tray for paper discharged from other discharge paths, so no useless space is generated and the recording apparatus main body can be downsized.

  In the above invention, in the reverse path, when a failure in the transport path is detected, the paper located in the forward path in the reverse path is discharged from the discharge port by the forward rotation of the transport mechanism and is returned to the return path or the normal path in the reverse path. The paper located in the paper feed path is preferably discharged from the discharge port by reverse rotation after the transport mechanism is temporarily stopped. In this case, since the transport mechanism in the reverse path can rotate forward and backward, for example, when a paper jam failure occurs, the paper staying in the transport path is positioned on the forward path in the reverse path. The paper can be discharged from the discharge table regardless of whether the paper is in the reverse path or the paper in the reverse path. As a result, the user does not have to take out the paper, and the jam clearing operation is facilitated.

  In the above invention, the image forming unit further includes a floating detection unit that detects the floating of the sheet upstream of the image forming unit on the conveyance path, and the reversing path is formed from the discharge port when the floating detection unit detects the floating of the sheet. It is preferable to execute the paper discharge. In this case, when the floating detection unit detects the floating of the paper, the drive part and the stop part of the conveyance path can be changed, and the paper staying on the reverse path is discharged via the image forming part. Therefore, the recording head can be prevented from being damaged by the contact between the recording head and the paper.

Another invention is a paper transport device having a transport path for transporting paper, and the transport path is branched and connected to a normal transport path from a paper feed path for supplying paper to a paper discharge path, and a normal transport path The paper is delivered from the normal conveyance path, and is constituted by a reversing path for reversing the front and back of the paper by reciprocating the paper by reversing the conveyance mechanism forward and backward and returning it to the normal conveyance path. Has a paper discharge port near the end of the forward path due to normal rotation, and continues the normal rotation operation of the transport mechanism until the paper passes through the transport mechanism, thereby discharging the paper from the discharge port. When a failure in the transport path is detected, the paper located in the forward path in the reverse path is discharged from the discharge port by the forward rotation of the transport mechanism, and is positioned in the return path in the reverse path or the paper feed path to the normal path The paper, after stopping temporarily transport mechanism, to be discharged from the outlet by the reverse rotation.

  As described above, according to the present invention, in an apparatus having a reversing path and capable of double-sided printing by switchback, by providing a discharge port in the reversing path and enabling discharge from here, It is possible to easily remove the paper staying in the conveyance path and to prevent the recording head in the image forming unit from being damaged when a paper failure occurs.

(Overall configuration of printing device)
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an outline of a printing paper conveyance path of the printing apparatus 100 according to the present embodiment. In the present embodiment, the printing apparatus 100 includes a plurality of ink heads having a large number of nozzles, prints black or color ink from each ink head, performs printing in units of lines, and prints on a recording sheet on a conveyance belt. An ink-jet line color printer that forms a plurality of images so as to overlap each other will be described as an example.

  As shown in FIG. 1, the printing apparatus 100 is an apparatus that forms an image on the surface of a sheet transported on an annular transport path. The transport path includes a paper feed system transport path FR that supplies the paper, and this paper feed. A general path CR from the system transport path FR through the head unit 110 to the paper discharge path DR and a reverse path SR branched and connected to the normal path CR are roughly configured.

  In the paper feed system conveyance path FR, as a paper feed mechanism for supplying printing paper, a side paper feed stand 120 disposed outside the side surface of the housing and a plurality of paper feed trays (inside the housing) 130a, 130b, 130c, 130d). A paper discharge port 140 is provided as a paper discharge mechanism for discharging printed printing paper.

  Printing paper fed from one of the side paper feed tray 120 and the paper feeding tray 130 is conveyed along a paper feeding system conveyance path FR in the housing by a driving mechanism such as a roller, and the printing paper It is guided to the resist portion R which is the reference position of the head portion. A head unit 110 having a plurality of print heads is provided further on the registration direction R in the transport direction side. The printing paper is image-formed line by line with ink ejected from each printing head while being conveyed at a speed determined by printing conditions by a conveying belt 160 provided on the opposite surface of the head unit 110.

  The printed printing paper is further conveyed on the normal route CR by a driving mechanism such as a roller. In the case of single-sided printing, in which printing is performed only on one side of the printing paper, the paper is directly discharged to the paper discharge port 140 through the paper discharge route DR, and is discharged as a tray for the paper discharge port 140. It is loaded on the table 150 with the printing surface facing down. The paper discharge table 150 has a tray shape protruding from the housing, and has a certain thickness. The paper discharge table 150 is inclined, and the printing paper discharged from the paper discharge port 140 is naturally arranged and overlapped by a wall formed at a position below the inclination.

  On the other hand, in the case of double-sided printing in which printing is performed on both sides of the printing paper, the front side (the first printed side is “front side” and the next printed side is “back side”). Without being guided to, the inside of the casing is further transported and sent out to the reverse path SR. For this reason, the printing apparatus 100 is provided with a switching mechanism 170 for switching the transport path for backside printing, and the printing paper that has not been sent to the discharge path by the switching mechanism 170 is drawn into the reversing path SR.

  In the reversing path SR, a sheet is transferred from the normal path CR, and a so-called switchback is performed in which the sheet is reversed by reciprocating the sheet. Then, it is returned to the normal route CR via the switching mechanism 172 by a driving mechanism such as a roller, and is fed again through the registration portion R, and the back side is printed by the same procedure as the front side. After that, the printing paper on which the back side is printed and the image is formed on both sides is guided to the paper discharge port 140 through the paper discharge route DR and discharged, and the paper discharged as a receiving base of the paper discharge port 140 is discharged. It is loaded on the table 150.

  In the present embodiment, switchback at the time of duplex printing is performed using a space provided in the paper discharge tray 150. The space provided in the paper discharge tray 150 is configured to be covered so that the printing paper cannot be taken out from the outside at the time of switchback. As a result, it is possible to prevent the user from accidentally pulling out the printing paper being reversed. Further, the paper discharge tray 150 is originally provided in the printing apparatus 100, and by performing switchback using the space in the paper discharge tray 150, a separate switchback is provided in the printing apparatus 100. There is no need to provide space. Therefore, an increase in the size of the housing can be prevented. Furthermore, since the paper discharge path and the reverse path are not shared, the switchback process and the paper discharge of other sheets can be performed in parallel.

  In the printing apparatus 100, one-side printed printing paper is also re-fed to the registration portion R, which is the reference position of the leading portion of the fed printing paper, during duplex printing. For this reason, a junction point where a transport path for newly fed printing paper and a refeed path for circulating and feeding back-side printing paper is formed immediately before the registration portion R. The Then, the registration unit R sends out the paper in the vicinity of the merging point between the paper feeding system conveyance path FR and the normal path CR.

  In the present embodiment, the path on the sheet feeding mechanism side is defined as the sheet feeding system conveyance path FR, and the other paths are defined as the conveyance paths based on the merging point. This transport path is annular, and includes the normal path CR and the reverse path SR as described above. FIG. 2 is a diagram schematically showing the sheet feeding system conveyance path FR, the normal path CR, and the reverse path SR. In the figure, the number of rollers constituting the drive unit is omitted as appropriate.

  In the paper feed system conveyance path FR, the side paper feed driving unit 220 for feeding paper from the side paper feed tray 120 and the paper feed from the paper feed trays 130 (130a, 130b, 130c, 130d) are provided. A tray 1 driving unit 230a, a tray 2 driving unit 230b,. These constitute a paper feeding means for feeding paper to the registration unit R.

  Further, any of the driving units (tray 1 driving unit 230a, tray 2 driving unit 230b...) In the above-described paper feeding system conveyance path FR includes a driving mechanism constituted by a plurality of rollers and the like. Are taken one by one and conveyed in the direction of the registration portion R. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with a paper feed mechanism that feeds paper.

  In addition, a plurality of conveyance sensors are arranged in the paper feeding system conveyance path FR so that a conveyance jam in the paper feeding system conveyance path FR can be detected. That is, each conveyance sensor is a sensor that detects the presence or absence of printing paper or the leading edge of printing paper. For example, a plurality of conveyance sensors are arranged at appropriate intervals on a conveyance path, and a conveyance sensor provided on the paper feeding side is provided. If the conveyance sensor on the conveyance direction side does not detect the printing paper within a predetermined time after detecting the printing paper, it can be determined that the conveyance jam has occurred.

  Among these conveyance sensors, the registration sensor in front of the registration unit R that sends out the paper measures the size of the paper that is being conveyed, and measures the size of the paper that is passing, for example, based on the passage speed and the passage time of the paper. If the conveyance sensor does not detect the printing paper within a predetermined time after driving the side paper feed driving unit 220, the tray 1 driving unit 230a, etc., it is determined that a conveyance jam (paper feeding error) has occurred. Can do.

  The normal path CR forms a part of the circulation transport path, and is a path from the paper feed system transport path FR for supplying paper to the paper discharge path DR through the head unit 110. An image is formed. The normal path CR includes a registration driving unit 240 that guides printing paper to the registration unit R, a belt driving unit 250 that drives the endless movement of the conveyance belt 160 provided on the opposite surface of the head unit 110, and a conveyance direction side. The first upper surface transport driving unit 260 and the second upper surface transport driving unit 265 arranged in order, the upper surface discharge driving unit 270 that guides the printed paper to the paper discharge port 140, and the drive for drawing the printing paper into the reverse path SR for back side printing. Means are provided. Each drive unit includes a drive mechanism composed of one or a plurality of rollers and the like, and conveys printing sheets one by one along the conveyance path. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with the conveyance status of the printing paper.

  Further, a plurality of conveyance sensors are also arranged on the normal route CR so that a conveyance jam in the normal route CR can be detected. Further, it is possible to confirm that the printing paper is properly conveyed also in the registration portion R. In the normal route CR, a conveyance sensor is provided corresponding to the drive unit, and it is possible to specify in which drive unit of the normal route CR the conveyance jam has occurred.

  The reversing path SR is branched and connected to the normal path CR, the paper is delivered from the normal path CR, and the paper is reciprocated (switched back) to return to the normal path CR, thereby reversing the front and back of the paper and the transport mechanism. The reversing path SR is provided with a reversing drive unit 281 that reverses the sheet and guides it to the joining point. The reverse route SR can be transported at a speed different from that of the normal route CR. When the paper is taken over from the normal route CR, acceleration / deceleration is performed, and a stop time at the time of switchback is extended or shortened. can do.

  In this embodiment, after a certain printing paper is fed, the next printing paper is not fed after waiting for printing to be performed on the printing paper and discharged. Before the printing paper is discharged, subsequent printing paper can be fed and printed continuously at a predetermined interval. Therefore, in normal scheduling at the time of duplex printing, a space is secured in advance so as to secure a position where the sheet returned from the reversing path SR is inserted when feeding the front sheet. Thereby, in this apparatus, printing on the front surface and printing on the back surface can be performed in parallel, and half the productivity can be ensured with respect to single-sided printing.

  The conveyor belt 160 is wound around a driving roller 161 and a driven roller 162 disposed at the front end and rear end of the surface facing the head unit 110, and rotates in the clockwise direction in FIG. On the upper surface of the conveyor belt 160, four ink heads of yellow (Y), magenta (M), cyan (C), and black (K) are arranged side by side along the belt moving direction, and a plurality of images are arranged. The head units 110 that form color images are arranged so as to face each other.

  Further, as illustrated in FIG. 1, the printing apparatus 100 includes an arithmetic processing unit 330. The arithmetic processing unit 330 is configured by a processor such as a CPU or DSP (Digital Signal Processor), memory, hardware such as other electronic circuits, software such as a program having the function, or a combination thereof. Various functional modules are virtually constructed by appropriately reading and executing a program, and various functional modules for processing related to image data, operation control of each unit, and user operations are constructed by each constructed functional module. Process. In addition, an operation panel 340 is connected to the arithmetic processing unit 330, and an instruction and a setting operation by a user can be received through the operation panel 340.

(Recovery mechanism)
In the present embodiment, the reverse path SR is provided with a recovery mechanism for jamming. FIG. 3 is an external view showing the recovery mechanism provided in the reversing path SR, and FIGS. 4 and 5 are explanatory views schematically showing the operation of the recovery mechanism.

  In the present embodiment, the reversing path SR uses a space 155 inside the paper discharge tray 150 provided as a receiving tray for the paper discharge outlet 140 as a space for paper to reciprocate, as shown in FIG. In addition, the paper discharge table 150 includes a casing portion 151 that surrounds an upper portion of a space 155 required for the reciprocation of paper, and a receiving table 152 disposed on the lower surface thereof.

  The casing 151 has an upper surface 151a serving as a receiving tray for paper discharged from another paper discharge path DR, and an opening 150a whose lower surface is opened. It has become. As shown in FIG. 3B, a plate-like pedestal 152 is attached to the lower surface opening 150a so as to cover from below. The cradle 152 is designed to be shorter than the length (paper transport direction) of the opening 150 a on the lower surface of the casing portion 151. When the cradle 152 is attached to the lower surface of the casing portion 151, An outlet 153 is opened at the tip of the lower surface.

  Further, as shown in FIG. 4, the inversion path SR includes an inversion unit SR2 that performs an inversion operation, an outward path SR1 from the normal path CR to the inversion unit SR2, and a path from the inversion unit SR2 to the normal path CR again. The casing 151 is located at the end of the reversing part SR2 in the forward direction (forward direction).

  Then, as shown in FIG. 5, in the lower surface opening 150 a, the paper is discharged in the vicinity of the forward end of the forward rotation by continuing the forward rotation operation of the transport roller 154 until the paper passes the transport roller 154. When discharging the paper, as shown in FIG. 5A, the paper is separated from the transport roller 154 and sent to the end in the space 155 by continuing the forward rotation operation of the transport roller 154. As shown in FIG. 5B, the fed sheet contacts the inner wall surface of the tip of the casing portion 151 (end of the forward path) and falls downward, and is received by the receiving base 152 from below. A stopper 152a protrudes from the end of the receiving base 152 on the apparatus side so that the paper dropped on the receiving base 152 does not move downward.

  Control of the recovery mechanism having such a configuration is performed in the arithmetic processing unit 330 described above. FIG. 6 is a block diagram illustrating the relationship between the module relating to the recovery mechanism of the arithmetic processing unit 330 and the surrounding modules. The “module” used in the description refers to a functional unit that is configured by hardware such as an apparatus or a device, software having the function, or a combination thereof, and achieves a predetermined operation. .

  As shown in FIG. 6, the module relating to the recovery mechanism includes a jam detection unit 331, an emergency stop control unit 332, a transport path control unit 333, and a paper discharge control unit 334.

  The jam detection unit 331 is a module that detects the occurrence of a failure in the transport path based on detection results from a floating sensor and other transport path sensors installed upstream of the head unit 110.

  The transport path control unit 333 is a module that controls the operation of each drive unit that drives each transport path including the reversing path SR and the normal path CR, and the operation of a drive mechanism such as the switching mechanism 170. The paper discharge control unit 334 is a module that controls a drive mechanism for paper discharge. Further, the transport path control unit 333 and the paper discharge control unit 334 also control a so-called recovery operation in which the paper stagnated in the transport path after an emergency stop is discharged.

  The emergency stop control unit 332 is a module that causes the transport path control unit 333, the paper discharge control unit 334, and the head unit 110 to perform an emergency stop or continuous operation. That is, the emergency stop control unit 332 controls the timing, operation speed, and operation direction for stopping the conveyance and printing processing in the case of an emergency stop, and does not make an emergency stop for the conveyance path that should continue to operate. Control to continue the operation.

  In this embodiment, by the control by the emergency stop control unit 332, the conveyance path control unit 333, and the paper discharge control unit 334, the reverse path SR detects a failure (jam) such as lifting or double feeding in the conveyance path. In this case, the forward rotation of the transport roller 154 is continued for the sheet that is being conveyed in the forward direction in the reversing path SR (that is, the sheet that is moving in the forward direction in the reversing unit and the sheet that is positioned in the forward path SR1). As a result, the sheet is discharged from the lower surface opening 150a at the end of the forward path and is being conveyed in the reverse direction on the reverse path SR (that is, the sheet being moved in the reverse direction on the reverse section SR2 and the refeed path SR3). Paper to be discharged) is temporarily discharged from the lower surface opening 150a by reverse rotation after the transport roller 154 is temporarily stopped.

(Recovery method)
The recovery method according to this embodiment can be implemented by the recovery mechanism specifically described above. FIG. 7 is a flowchart showing the operation of the recovery mechanism according to the present embodiment.

  When the paper is transported and printed in the transport path by the normal printing process (S101), the paper is lifted upstream of the head unit 110, and when the jam detection unit 331 detects this (S102), Based on the detection result from the conveyance path sensor, it is determined whether double-sided printing is in progress (S103). This determination may be made based on the scheduling.

  If it is determined in this step S103 that single-sided printing is in progress (“single-sided” in S103), a normal discharge operation is executed assuming that no paper is present in the reversing path SR (S104). On the other hand, if it is determined that double-sided printing is being performed (“double-sided” in S103), it is determined whether or not a transport operation is being executed in the reverse path SR (S105). If the reversing path SR is not in the carrying operation (“N” in S105), a normal discharge operation is performed assuming that no sheet exists on the reversing path SR (S104).

  If the reversal path SR is in the carrying operation (“Y” in S105), it is then determined whether or not the carrying roller 154 is in the forward rotation operation (S106). If the normal rotation operation is being performed (“Y” in S106), the normal rotation operation is continued until the paper passes the transport roller 154, and the paper is discharged from the opening 150a at the end of the reverse path SR (S107). If the reversing operation is being performed ("N" in S106), the conveying roller 154 is temporarily stopped (S108), the conveying roller 154 is switched to the normal rotating operation, and is positioned on the return path or the refeeding path SR3 of the reversing path SR. The paper is discharged from the lower surface opening 150a (S109).

(Action / Effect)
According to the present embodiment as described above, the lower surface opening 150a is provided in the reversing path SR, and the sheet stagnated in the reversing path SR can be discharged by using the forward rotation operation of the transport roller 154. Thus, it is possible to easily remove the sheet in the reversing path SR.

  Further, in the lower surface opening 150a, when a jam occurs, for example, when the floating detection unit detects the lifting of the sheet by providing the plate-shaped receiving base 152 disposed below the space required for the reciprocation of the sheet. In addition, when the paper is discharged from the lower surface opening 150a, the paper can be received from below, and the user can easily take out the paper. In particular, in the present embodiment, since the upper surface 151a of the casing portion 151 is a receiving tray for paper discharged from the paper discharge path DR, no wasteful space is generated, and the recording apparatus main body can be downsized.

  Further, by causing the transport roller 154 in the reversing path SR to rotate forward and backward, for example, when a paper jam failure occurs, even if the paper is located on the forward path in the reversing path SR, Even if the sheet is located on the return path, the sheet can be discharged from the cradle 152, and the user can remove the sheet by himself / herself, thereby facilitating the jam clearing operation.

  As a result, according to the present embodiment, it is easy to remove the paper staying in the conveyance path, and the head unit 110 can be prevented from being damaged when a jam occurs.

It is a figure which shows the outline | summary of the printing paper conveyance path | route of the printing apparatus which concerns on embodiment. FIG. 6 is a diagram schematically illustrating a sheet feeding system conveyance path FR, a normal path CR, and a reverse path SR according to the embodiment. It is an external view which shows the recovery mechanism provided in the inversion path | route SR which concerns on embodiment. It is explanatory drawing which shows typically operation | movement of the recovery mechanism which concerns on embodiment. It is explanatory drawing which shows typically operation | movement of the recovery mechanism which concerns on embodiment. It is a block diagram which shows the module which concerns on the recovery mechanism of the arithmetic processing part which concerns on embodiment. It is a flowchart figure which shows operation | movement of the recovery mechanism which concerns on embodiment.

Explanation of symbols

CR ... Normal route DR ... Discharge route FR ... Paper feed route R ... Registration SR SR ... Reverse route 100 ... Printer 110 ... Head unit 120 ... Side paper feed stand 130 ... Feed tray 140 ... Discharge port 150 ... Discharge table 150a ... lower surface opening 151 ... casing portion 151a ... upper surface 152 ... receiving table 153 ... outlet 154 ... conveying roller 155 ... inner space 160 ... conveying belt 161 ... driving roller 162 ... driven roller 170, 172 ... switching mechanism 220 ... Side paper feed drive unit 230a, 230b ... Tray drive unit 240 ... Registration drive unit 250 ... Belt drive unit 260 ... First upper surface transport drive unit 265 ... Second upper surface transport drive unit 270 ... Upper surface discharge drive unit 281 ... Reverse drive unit 330 ... Calculation processing unit 331 ... Jam detection unit 332 ... Emergency stop control unit 333 ... Conveyance path control unit 3 34 ... Paper discharge control unit 340 ... Operation panel

Claims (2)

A recovery mechanism of a printing apparatus having an image forming unit that forms an image on a sheet surface conveyed on a conveyance path,
The transport path is
A normal transport path from the paper feed path for supplying the paper to the paper discharge path via the image forming unit;
Branched and connected to the normal conveyance path, the paper is delivered from the normal conveyance path, and the paper is reciprocated by rotating the conveyance mechanism forward and backward to return the paper to the normal conveyance path. It consists of an inversion path to invert,
The reversing path has a paper discharge port in the vicinity of the forward path end by the forward rotation,
By continuing the forward rotation operation of the transport mechanism until the paper passes through the transport mechanism, the paper is discharged from the discharge port ,
In the reverse path, when a failure in the transport path is detected,
The paper located in the forward path in the reverse path is discharged from the discharge port by the forward rotation of the transport mechanism,
The printing apparatus characterized in that the paper located on the return path in the reverse path or the paper feed path to the normal path is discharged from the discharge port by reverse rotation after the transport mechanism is temporarily stopped. Recovery mechanism. A paper transport device having a transport path for transporting paper,
The transport path is
A normal transport path from the paper feed path for supplying the paper to the paper discharge path;
Branched and connected to the normal conveyance path, the paper is delivered from the normal conveyance path, and the paper is reciprocated by rotating the conveyance mechanism forward and backward to return the paper to the normal conveyance path. It consists of an inversion path to invert,
The reversing path has a paper discharge port in the vicinity of the forward path end by the forward rotation,
By continuing the forward rotation operation of the transport mechanism until the paper passes through the transport mechanism, the paper is discharged from the discharge port,
In the reverse path, when a failure in the transport path is detected,
The paper located in the forward path in the reverse path is discharged from the discharge port by the forward rotation of the transport mechanism,
The paper located in the reverse path in the reverse path or the paper feed path to the normal path is discharged from the discharge port by reverse rotation after the transport mechanism is temporarily stopped.
A sheet conveying apparatus characterized by the above .