JP2002108122A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the defective fixing of an unfixed toner image caused by the transportation suspension of a paper sheet accompanying the suspension of an image forming operation in an image forming apparatus for continuous forms. SOLUTION: When the reception of printing data is completed and an image forming operation is suspended (steps S106 and S107), the transportation of continuous forms is also suspended accordingly, and a printing standby state is set (step S109). When the time Tw of the printing standby exceeds a prescribed value Ta (Y in a step S113), the suspended continuous forms are fed ahead and the unfixed toner image is fixed by a fixing device (steps S116 and 117). After fixing is completed (Y in a step S118), a reverse transportation of paper is performed to retreat the continuous forms and to restore the original printing standby (step S123).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus for forming an image on continuous paper, and more particularly, to paper feed and fixing control.

[0002]

2. Description of the Related Art A so-called electrophotographic image is formed by forming a latent image on the surface of a photoreceptor and developing and transferring the latent image using toner to form an image on a transfer material such as a recording sheet. Some of the forming apparatuses use a continuous paper as a transfer material. The continuous paper is provided with perforations or the like at predetermined intervals in the longitudinal direction of the paper, and can be cut off at the perforations where image formation is completed and can be provided for later use.
For example, it is very useful when printing a large amount of data continuously and at high speed in a large computer or the like.

FIG. 8 shows a conventional image forming apparatus 4 for continuous paper.
FIG. 2 is a schematic cross-sectional view showing a configuration of a 00. As shown in the figure, the image forming apparatus 400 pulls in the continuous paper S placed on the continuous paper placing unit 410 and places toner on the continuous paper S based on print data received from an external computer or the like. An electrophotographic image forming unit 420 for forming an image, a flash fixing device 430 for fixing the toner image formed in the image forming unit 420, and a discharge unit for storing the continuous paper on which the toner image has been fixed while folding the continuous paper at the fold line Paper storage unit 4
40.

[0004] Here, a flash fixing device irradiates a transfer material onto which a toner image has been transferred with flash light for a certain period of time using a light source such as a xenon lamp, and raises the temperature of the toner by the irradiation energy of the flash light. By fixing the toner image, the toner image is fixed, and can be fixed in a non-contact manner as needed. Therefore, the toner image is often used in an image forming apparatus for continuous paper.

By the way, in order to maximize the function of printing a large amount of data continuously and at high speed,
In the conventional continuous paper image forming apparatus, when the input of the print data is completed and the image forming operation is temporarily stopped, the conveyance of the continuous paper S is also stopped, and the image forming operation is performed by receiving the next print data. , The control is performed so that the continuous paper S is conveyed again.

[0006]

However, if the conveyance of the continuous paper S is stopped in accordance with the stop of the image forming operation as described above, the flash fixing from the transfer position of the photosensitive drum 421 of the image forming unit 420 is performed. An unfixed toner image remains on the continuous paper S located before the fixing position of the device 430.

When the next print data is received immediately and the image forming operation is restarted, the conveyance of the continuous paper S is started almost simultaneously, and the toner image in the unfixed portion is immediately fixed by the flash fixing device 430. Therefore, there is no particular problem. However, when the image forming operation is not restarted even after the lapse of a predetermined time, there is a problem that a fixing failure of the unfixed toner image occurs. That is, the inside of the housing of the image forming apparatus 400 has a high-temperature and high-humidity atmosphere due to heat generated during flash fixing and heat generated by each drive motor, and the toner image is left unfixed in such an atmosphere. Then, the continuous paper in the portion where the toner image is formed absorbs moisture in the surrounding air, and its heat capacity increases.

The output of the flash fixing device is set so that an optimal amount of heat is applied to a toner image formed on a sheet placed in a normal environment. If the heat capacity of the toner image is increased and excess heat is deprived of the heat capacity, the amount of heat applied to the toner image becomes insufficient, thereby causing defective fixing. In order to avoid such a situation, it is conceivable to control the paper transport system and the flash fixing device so that the continuous paper is fed forward and the toner image is fixed each time the imaging operation is stopped, and then the paper is retracted to the original position. However, such processing requires some time, and if print data is received during that time, the printing operation must be started after the completion of the fixing / transporting operation. Printing process is delayed. In particular, in a use environment where print data reception and stop are frequently repeated, if the above-mentioned advanced fixing and retreat operations are repeated every time the image forming operation is stopped, the efficiency of the printing process is significantly deteriorated. As a result, the function of high-speed and continuous printing cannot be sufficiently exhibited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and in a continuous paper image forming apparatus, the occurrence of a fixing defect is minimized while minimizing a reduction in the processing speed of continuous image formation. It is an object of the present invention to provide an image forming apparatus that can prevent the occurrence of a failure.

[0010]

In order to achieve the above object, an image forming apparatus according to the present invention feeds continuous paper to an image forming section by a paper feeder to form a toner image on the continuous paper. An image forming apparatus that forms an image by fixing the same with a fixing device, and stops the continuous paper feeding operation along with the stop of the image forming operation in the image forming unit to enter a print standby state. If the stop time of the imaging operation exceeds the predetermined time,
The stopped continuous paper is fed forward to fix the unfixed toner image by the fixing device, and after the fixing is completed, the paper feeding device is retracted to return the continuous paper to the original print standby state. It is characterized by comprising control means for controlling.

With this configuration, it is possible to feed the continuous paper forward, fix it, and then retreat to return to the print standby state only when there is a possibility that a fixing failure of the unfixed toner image may occur. It is possible to avoid a delay in image forming processing caused by unnecessarily advancing and fixing each time image formation is stopped, and to prevent occurrence of fixing failure.

Here, the "print standby state" means that a portion of the continuous paper immediately after a portion where the toner image has already been formed is kept in the image forming section, and that the next portion of the continuous paper is This also includes making the image forming unit stand by at the top of the page. Further, the image forming apparatus according to the present invention is configured such that the image forming unit forms a toner image on the surface of the photoreceptor, and transfers the image to continuous paper at a predetermined transfer position. The fixing device is a flash fixing device using a flash lamp. When the unfixed toner image is fixed, the continuous paper is transferred to the transfer position or a position closer to the fixing device than the transfer position. A paper pressing means for pressing the paper.

When the unfixed toner image is fixed as described above, the continuous paper is pressed against the surface of the photoreceptor at the transfer position or at a position closer to the fixing device than the transfer position. Leakage light and primary reflected light from a flash fixing device often used in a forming apparatus are less likely to be incident on the surface of the photoreceptor, and deterioration of the photoreceptor due to light fatigue can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image forming apparatus according to the present invention will be described with reference to the drawings. (1) Overall Configuration of Image Forming Apparatus FIG. 1 is a schematic sectional view showing the overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 according to the present embodiment forms an image on continuous paper S by an electrophotographic method. The image forming apparatus 1 includes an image forming unit 10 and a continuous paper bundle ST stacked beside the image forming apparatus main body. Paper supply unit 2 including tractor feeder 21 that supplies continuous paper S to image unit 10
0, a paper transport unit 30 that transports the continuous paper S on which the toner image is formed by the image forming unit 10 further forward, a flash fixing device 40, and a paper discharge storage unit 50.

The image forming unit 10 is a well-known device in which a static elimination lamp 12, a charging charger 13, a developing unit 14, a transfer charger 15, a separation charger 16 and the like are arranged around a photosensitive drum 11 as an example of a photosensitive member. Things. Imaging unit 1
At 0, the charge is removed by the charge removing lamp 12 and the surface of the photosensitive drum 11 is uniformly charged by the charging charger 13, and then emitted from a semiconductor laser (not shown) and deflected by the polygon mirror 5 by the laser beam LB. Then, the surface of the photosensitive drum 11 is exposed to form an electrostatic latent image.

The formed electrostatic latent image is visualized as a toner image by the developing device 14, and the toner image is transferred onto the continuous paper S conveyed by the tractor feeder 21 by the operation of the transfer charger 15. You. The continuous paper S to which the toner image has been transferred is separated from the photosensitive drum 11 by the separation charger 16, and the transfer belt 31 and the fan 36
Is sent to the flash fixing device 40 via the paper transport unit 30 including The flash fixing device 40 is a known device that irradiates a toner image with flash light from a light source 41 (see FIG. 3) such as a xenon lamp to raise the temperature of the toner and fix the toner image. Continuous paper S on which the toner image is fixed by the flash fixing device 40
Is sent out to the paper output storage section 50 via the paper output roller 37.

The paper discharge storage unit 50 is configured so that the mounting table 51 is moved up and down by an elevating mechanism 52 so that the upper surface of the stacked continuous paper S is within a substantially constant height range. By rotating the paddle 53 and pressing the fold of the continuous paper S, the placed continuous paper S is prevented from becoming bulky. In addition, the elevation control of the elevation mechanism 52 and the rotation control of the rotary paddle 53 are known, and will not be described in detail here.

Reference numeral 60 denotes a control unit for controlling the signal processing of the received print data and the operation of each unit. 2A and 2B are partially enlarged views showing the configuration of the image forming unit 10 at the transfer position. In FIG. 1, only the developing roller 141 of the developing device 14 is shown for convenience. As shown in FIG. 2A, the tractor feeder 21 of the paper feeding unit 20 is provided with a roller 22 having projections 222 projecting at equal pitches on its peripheral surface. S is engaged with an engaging hole (not shown) continuously provided at a predetermined pitch along both sides of the sheet S, and the roller 22 is rotated by a stepping motor (not shown), so that the continuous paper is reliably formed. Are transported. A pressing guide 23 for pressing the continuous paper S against the surface of the photoconductor drum 11 is held at a leading end of the tractor feeder 21 via a frame 24. The frame 24 is provided with a rotating shaft 2 of the roller 22.
The roller 21 is pivotally supported at two positions, a front end and a rear end, and can swing up and down, and transfers the toner image formed on the surface of the photosensitive drum 11 to the continuous paper S. 2A and at the time of fixing unfixed toner described later, FIG.
As shown in (2), the frame 24 is pushed up by the solenoid 25, and the continuous paper S is pressed against the surface of the photosensitive drum 11 by the pressing guide.

When the image forming operation is stopped, the operation shown in FIG.
As shown in (b), the pressing guide 23 is moved downward to separate the continuous paper S from the surface of the photosensitive drum 11. Normally, the photosensitive drum 11 is rotated for a while even while the image formation is stopped, the surface of the photosensitive drum 11 is neutralized by the neutralization lamp 12, and the image forming operation can be immediately started when the next print data is received. (Hereinafter, this is referred to as “idling around the photoconductor”.) If the continuous paper S is pressed against the photoconductor drum 11 during that time, the surface of the photoconductor drum 11 is worn and deteriorated. Because it is easy to do.

The transfer charger 15 and the separation charger 16 are also held by a frame 24 via an arm member (not shown), and move up and down as the frame 24 swings. When the continuous paper S is separated from the photosensitive drum 11 as shown in FIG. 2B, the transfer charger 15 and the separation charger 16 are also lowered, so that the transfer charger 15 and the separation charger 16 are separated from the photosensitive drum 11. The paper S is configured so as not to be in contact with the back surface. The mechanism for swinging and driving the frame 24 is not limited to the solenoid 25 described above.
The spur gear is loosely inserted into the rotary shaft 221 and fixed to the frame 24, and the spur gear is rotated by meshing with a pinion attached to a drive shaft of a stepping motor different from the drive source of the tractor feeder. , The frame 24 can be driven to swing.

Next, the configuration of the sheet transport unit 30 will be described. The paper transport unit 30 transports the continuous paper S to the transport belt 3
1 to prevent the unfixed toner from scattering due to vibrations, etc., while preventing leakage light and primary reflected light from the flash fixing device 40 from the surface of the photosensitive drum 11. Is prevented from being reached.

FIG. 3 is an enlarged side view of the sheet conveying section 30 in the present embodiment. As shown in the figure, the paper transport unit 30 includes a drive roller 32 and a driven roller 33 for moving the transport belt 31 in the paper transport direction, and a transport belt 31 is provided between the two rollers. A guide member 34 is provided for running the vehicle in a mountain shape.

FIG. 4 is an external perspective view of the paper transport unit 30. As shown in FIG.
While the suction window 341 is provided at a plurality of locations, the transport belt 31 is also provided with a plurality of holes 311, and the frame 36 side of the transport belt 31 is negatively operated by a fan 36 provided below the transport belt 31. By making it pressure state,
When the continuous paper S is transported, the continuous paper S is configured to be brought into close contact with the transport surface of the transport belt 31. By bringing the continuous paper S into close contact with the transport surface of the transport belt 31 in this manner,
Even when an image is formed on the first sheet of the continuous paper S, the image can be properly guided to the fixing position by the flash fixing device 40 without scattering of the unfixed toner image. It can be used for image formation from the eyes, thereby preventing continuous paper from being wasted. Although the guide member 34 is supported by the frame 35 in the present embodiment, the shape, material, and the like of the frame 35 are not particularly limited.

Further, the shape, number, arrangement position, and the like of the holes 311 and the suction windows 341 are not limited to those shown in the drawing, but a suction port portion (e.g., the suction window 341) that exerts a suction action is used. It is not limited to the window type, and includes a gap to be described later.) At least at the top portion of the guide member 34 so that the continuous paper S can be sucked at the top portion of the transport belt 31 raised in the mountain shape. Preferably. This is because, in particular, when the paper quality of the continuous paper S is hard, it is possible to prevent the continuous paper S from peeling off from the transport surface of the transport belt 31.

FIG. 5 is a perspective view of the flash fixing device 40. Flash fixing device 40 of the present embodiment
Is a light source 41 such as a xenon lamp surrounded by a cover member 42 having an opening 43 on the transfer material side. The transfer material is irradiated with flash light from the opening 43, and the cover member 42 The flash light from the flash fixing device 40 is prevented from directly reaching the surface of the photosensitive drum 11.

In the present embodiment, flash light and primary reflected light from the opening 43 due to the swelling of the conveyor belt 31 are prevented from reaching the surface of the photosensitive drum 11. Specifically, the cover member 42 is formed so that the side 44 of the opening 43 in FIG. 5 on the photosensitive drum 11 side is substantially linear. Further, the surface of the conveyor belt 31 is substantially the same as the surface substantially including the side 44 and which is in contact with the surface of the photosensitive drum 11 on the side of the transfer charger 15 (the surface including the dotted line P in FIG. 3 and perpendicular to the paper of FIG. 3). By forming the guide member 34 so that there is a portion where is located above,
The flash light and the primary reflected light from the opening 43 of the flash fixing device 40 can be prevented from reaching the surface of the photosensitive drum 11. Thus, the guide member 34
By molding, the flash light and primary reflected light,
This is because the light is reflected by the continuous paper S in a direction different from the direction of the photosensitive drum 11. In the above description, "the side 44 is substantially linear" means that it is not necessary to be a strict straight line. Therefore, the dotted line P in FIG. It is noted that the flash light and the primary reflected light are
The deformation of the member is allowed as long as it can be prevented from reaching.

The light (secondary reflected light) reflected by the primary reflected light to other parts such as the inner wall of the casing of the image forming apparatus is not limited to the inner wall of the casing of the image forming apparatus and other members (primary reflected light). It is possible to prevent the light from reaching the surface of the photoreceptor drum 11 by making the member (which may reflect light) black or have a light absorbing structure. In addition, the inner wall may be made uneven to cause irregular reflection.

Further, as for the guide member 34, if the transport belt 31 is configured to bend in a mountain shape and transport the continuous paper S, not only the guide member shown in FIG. Needless to say, this is possible.
In addition, a structure is also possible in which an auxiliary roller is provided on the inner peripheral surface side of the transport belt 31 without using the guide member, and the transport belt 31 is pulled up by using the auxiliary roller so as to bulge in a mountain shape. . Although the thickness of the auxiliary roller is not particularly limited, in order to prevent the suction effect of the transfer material at the top of the transport belt 31 from decreasing,
It is considered preferable to make the diameter slightly smaller.

In the present embodiment, the continuous paper S is sucked by the fan 36 in order to bring the continuous paper S into close contact with the conveying surface of the conveying belt 31. For example, various suction methods are possible. In the conventional image forming apparatus 400 shown in FIG. 8, the fixing device 430 is placed in another housing so that light leaked from the flash-type fixing device 430 does not enter the photosensitive drum in the image forming unit 420. In addition to being stored, it is arranged at a distance from the image forming unit 420. For this reason, there is a problem that the size of the apparatus is increased. However, by configuring the conveyance path of the paper conveyance unit 30 to have a mountain shape as in the present embodiment, the flash fixing device 40 is arranged near the image forming unit 10. However, the possibility that flash light is incident on the photosensitive drum 11 is reduced,
The device can be made compact.

FIG. 6 is a block diagram showing the configuration of the control unit 60. As shown in FIG.
61, a signal receiving unit 62, an image memory 63, an LD drive circuit 64, a ROM 65, a RAM 66, and the like. When data transmitted from a terminal such as an external computer is received by the signal receiving unit 62, the data is separated into header information / footer information and print data, and the header information and footer information are sent to the CPU 61 and ,
The print data is stored in the image memory 63 after being subjected to known image processing. The header information includes a print request signal, and the footer information includes a signal indicating the end of data transmission. The image processing performed on the print data includes, in addition to edge enhancement processing, font development when the print data is a character code. Further, when the print data is encoded, a process for decoding the encoded data is also included. Note that “print data” in this specification is used as a concept that includes image data in addition to the character code data.

The CPU 61 receives a print request command from the signal receiving unit 62 and receives a print request command.
0 and the other driving units such as the paper feed unit 20 and the paper discharge storage unit 50 are controlled.
Is also controlled. In accordance with these controls, the print data stored in the image memory 63 is read out,
The laser diode (not shown) of the image forming unit 10 is driven via the D drive circuit 64 to smoothly execute the above-described image forming operation.

The ROM 65 stores a control program for executing the above-described image forming operation, and data such as threshold values necessary for the control. Also, in the RAM 66,
Various control variables for temporarily executing the control program are temporarily stored and serve as a work area when the control program is executed. The present invention is characterized in that the fixing process of the unfixed toner image is executed early, and the control operation in this case will be described below with reference to the flowchart of FIG.

First, in step S101, it is determined whether print data has been received from an external computer or the like. Note that this determination can be easily made based on whether or not a print request signal has been received from the signal receiving unit 62. Upon receiving the print data, the image forming unit 10 starts an image forming operation based on the print data (step S102).
At this time, the pressing guide 23 is displaced upward to press the continuous paper S against the photosensitive drum 11 (step S103), and the paper feeding unit 20 and the paper transporting unit 3
0 to start the transport operation of the continuous paper S (step S1).
04). The reason why the continuous paper S is pressed against the photosensitive drum 11 in step S103 is to improve the transfer state. At the timing when the transferred toner image reaches the flash fixing device 40, the fixing operation of the toner image by flash emission is started. At this time, the flash fixing device 40 is controlled by the CPU 61 such that the flash lamp is intermittently emitted at predetermined intervals in accordance with the transport speed of the continuous paper S, and the toner image on the continuous paper S is fixed without leakage. .

When the completion of the reception of the print data is confirmed by the footer information included in the received data (step S).
106), the image forming operation and the fixing operation are stopped (step S1).
07, S108), in accordance with the stop of the image forming operation, the paper transporting operation by the paper feeding unit 20 and the paper transporting unit 30 is stopped to be in a printing standby state (step S109), and the standby time is calculated by counting the internal clock. The timing of Tw is started (step S110). And the pressing guide 2
3 is moved downward to release the pressing of the continuous paper S against the photosensitive drum 11 (step S111). At this time, the photoconductor drum 11 is kept rotating, and the above-described idling around the photoconductor is executed (step S112).

Next, the CPU 61 determines whether or not the standby time Tw of the image forming operation is longer than a predetermined value Ta (step S113). When the continuous paper S is left as it is under the worst in-machine environment, the predetermined value Ta absorbs the surrounding moisture, thereby increasing the heat capacity to a non-negligible level, and possibly causing a fixing failure. A slightly smaller time is set and is obtained in advance by experiments or the like. In the present embodiment, “60 seconds” is previously stored as a fixed value in the ROM 65 as the predetermined value Ta, but this value can be changed by input from an operation panel (not shown), or If the printer driver of the terminal and the control program of the control unit 60 are set so that the value of the predetermined value Ta can be changed, the image forming apparatus can be flexibly adapted to the usage environment and more convenient.

In step S113, Tw> T
If not, it is determined whether or not the next print data has been received (step S114).
Returning to step 102, image formation is started based on the print data and the above operation is repeated (steps S102 to S11).
3) If the next print data has not been received, the flow returns to step S113 to determine again whether or not the standby time Tw has exceeded the predetermined value Ta.
The subsequent unfixed toner fixing process is executed.

In this process, first, the pressing guide 23 is moved upward to press the continuous paper S at the transfer position of the photosensitive drum 11 (step S115). As described above, when the unfixed toner image is fixed, the continuous paper S is pressed against the photosensitive drum 11 so that the exposed portion of the photosensitive drum 11 is reduced, and the primary reflection light due to the paper surface at the transfer position is eliminated. Since the amount of light incident on the surface of the photoconductor drum 11 is reduced, light deterioration of the photoconductor can be significantly suppressed.

Then, the operation of transporting the continuous paper S by the paper supply unit 20 and the paper transport unit 30 is started (step S11).
6). At about the same timing, the fixing of the unfixed toner by the flash fixing device 40 is started (step S1).
17) When the fixing of the unfixed toner image is completed (Y in step S118), the idling around the photoconductor is ended, the fixing operation and the paper transport operation are stopped, and the paper on the photoconductor drum 11 is stopped. The pressure contact is released (steps S119 to S122).

In step S118, whether or not the fixing process of the unfixed toner image is completed is determined by dividing the transport path length from the transfer position in the image forming unit 10 to the fixing position of the flash fixing device 40 by the paper transport speed. It can be easily executed by elapse of time or by counting the number of drive pulses input to the stepping motor, which is the drive means of the tractor feeder 21.

Photosensitive drum 1 in step S122
1 and the paper feed unit 20 and the paper transport unit 3
In step S123, the respective drive motors of No. 0 are rotated in the reverse direction to reverse the continuous paper S to the original print standby state (step S123). This is because the continuous paper S is advanced during the unfixed toner fixing operation, or
This is executed by retreating by the number of drive pulses input to the stepping motor. As a result, the next time the print data is received and printing is started, there is a printing position and interval between the print data before the printing is stopped, so that paper is not wastefully consumed. Since the continuity of the printing position can be ensured, the user does not feel uncomfortable when browsing after output.

Thus, a series of control operations centering on the image forming operation after receiving the print data and the fixing process of the unfixed toner image is completed. If the next print data is received during the fixing process of such an unfixed toner image, the image formation for the print data is waited until the paper reverse transport process in step S123 is completed. However, in the present embodiment, since the distance between the transfer position of the image forming unit 10 and the fixing position by the flash fixing device 40 is devised as shown in FIG. The length of the applied toner image in the paper transport direction is not so long, the time required for the fixing process of the unfixed toner image is relatively short, and the effect on high-speed printing is small.

(Modification) Although the laser scanning device according to the present invention has been described based on the embodiment, it goes without saying that the content of the present invention is not limited to the above-described embodiment. Such a modification can also be implemented. (1) In the above embodiment, the conveyance of the continuous paper S is stopped simultaneously with the stop of the image forming operation in the image forming unit 10 (see FIG. 7, step S109). In most cases, this coincides with the end of one print job. Therefore, when the image forming operation is stopped, the print position of the next page may be advanced so as to reach the transfer position and then stopped.

(2) In the above embodiment,
When the unfixed toner image is fixed, the continuous paper S is pressed against the photosensitive drum 11 by using the pressing guide 23 used at the time of transfer (see FIG. 7, step S115), thereby leaking from the flash fixing device 40. Although the flash light is prevented from being incident on the photoreceptor and causing fatigue, the transfer position or a position closer to the transfer position than the flash fixing device 40 and which does not particularly hinder the conveyance of the continuous paper. , A pressing device for pressing the continuous paper S against the surface of the photosensitive drum 11 may be separately provided.

(3) In the above embodiment,
A flash fixing device was used as a fixing device. When the continuous paper is used as the transfer material, the flash fixing device is used in order to prevent the continuous paper and the toner image from being adversely affected by excessive heating. That is, when a press-contact type fixing device that fixes the toner image by applying pressure while heating the toner image by passing between the fixing roller pairs is used, while the continuous paper is stopped without receiving print data as described above, Since a specific portion of the continuous paper at the fixing position is heated by the fixing roller, which results in deterioration of the paper quality of the continuous paper and deterioration of the toner, it is necessary to prevent such a situation. Because there is. In this regard, the flash fixing device is not in contact with the continuous paper, and does not apply heat unless the flash lamp is turned on. Absent.

Therefore, even if the fixing device is of the pressure contact type, while the conveyance of the continuous paper is stopped, the fixing roller is separated from the surface of the continuous paper by an appropriate distance so that the influence of the heat is reduced by the toner image. If such a configuration is not provided, it can be sufficiently used in the present invention. In addition,
When the pressure-contact type fixing device is used as described above, there is no possibility of causing the photoconductor drum 11 to be lightly fatigued.
During the fixing process of the unfixed toner image, the photosensitive drum 11
There is no need to press the continuous paper S against the
It is no longer necessary to configure the conveyance path of the 0 conveyance belt 31 to have a mountain shape.

(4) Further, in the above embodiment, the toner image fixed by the fixing process of the unfixed toner image is transferred to the fixing position of the flash fixing device 40 by the sheet reverse conveyance process in step S123 in FIG. Since the image returns to the photosensitive drum 11 side, when the next print data is received and the image forming and the sheet conveyance are started, the sheet passes through the flash fixing device 40 again. Since it does not make much sense to fix the already fixed toner image again, the flash fixing device 40 is not operated until the fixed portion of the continuous paper S passes, and the newly transferred unfixed toner image is fixed. It is needless to say that it is desirable to wait for the toner image to reach the fixing position before starting the fixing operation by flash emission.

(5) In the above embodiment, the image forming apparatus for continuous paper with perforations has been described. However, even in the case where continuous paper such as roll paper is used as a transfer material. Applicable. Further, the present invention can be applied not only to a printer but also to a complex type copying machine capable of forming an image based on external data.

[0048]

As described above, according to the image forming apparatus of the present invention, continuous image forming is performed only when there is a possibility that the image forming stop time is longer than the predetermined time and a fixing failure of the unfixed toner image may occur. Since the paper is advanced and fixed, and then retracted and returned to the original print standby state, the image forming process is delayed when the image is unnecessarily advanced and fixed each time image formation is stopped. While avoiding
The fixing operation can be executed only when necessary, thereby preventing the occurrence of the fixing failure.

Further, according to the present invention, when fixing an unfixed toner image, the continuous paper is pressed against the surface of the photoreceptor at the transfer position or at a position closer to the fixing device than the transfer position. Leakage light and primary reflected light from a flash fixing device, which is often used in continuous paper image forming apparatuses, are less likely to be incident on the surface of the photoreceptor, and deterioration of the photoreceptor due to light fatigue can be reduced. With this configuration,
The flash fixing device can be arranged near the image forming unit, which contributes to downsizing of the entire device.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an overall configuration of an image forming apparatus for continuous paper according to an embodiment of the present invention.

FIGS. 2A and 2B are enlarged views of a vicinity of a transfer position in an image forming unit of the image forming apparatus, wherein FIG. 2A illustrates a state in which continuous paper is pressed against the surface of a photosensitive drum, and FIG. It is a figure which shows the state separated from the photosensitive drum surface, respectively.

FIG. 3 is an enlarged side view of a sheet transport unit in the image forming apparatus.

FIG. 4 is a perspective view of the sheet transport unit.

FIG. 5 is a perspective view of a flash fixing device in the image forming apparatus.

FIG. 6 is a block diagram of a control unit in the image forming apparatus.

FIG. 7 is a flowchart illustrating an image forming process and a fixing process of an unfixed toner image performed by the control unit.

FIG. 8 is a schematic sectional view showing an example of a configuration of an image forming apparatus for continuous paper using a conventional flash fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image forming part 11 Photoreceptor drum 15 Transfer charger 16 Separation charger 20 Paper feed part 21 Tractor feeder 23 Press guide 24 Frame 25 Solenoid 30 Paper transport part 40 Flash fixing device 50 Discharge storage part 60 Control part 61 CPU 62 signal receiving unit 63 image memory 64 LD drive circuit 65 ROM 66 RAM

Claims (2)

[Claims] 1. An image forming apparatus for feeding a continuous paper to an image forming unit by a paper feeding device, forming a toner image on the continuous paper, and fixing the toner image by a fixing device to form an image. With the stop of the image forming operation in the image section, the continuous sheet feeding operation is stopped to be in a printing standby state, and when the image forming operation stop time exceeds a predetermined time, the stopped continuous sheet is moved forward. And a control unit that controls the paper feeder so that the unfixed toner image is fixed by the fixing device, and after the fixing is completed, the continuous paper is retracted to return to the original print standby state. Characteristic image forming apparatus. 2. The image forming section is configured to form a toner image on a surface of a photoreceptor, and to transfer the image to continuous paper at a predetermined transfer position. An apparatus, comprising: a paper pressing unit that presses the continuous paper against the surface of the photoconductor at the transfer position or at a position closer to the fixing device when the unfixed toner image is fixed. The image forming apparatus according to claim 1.