JP2015230331A - Image forming apparatus and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a reduction in operation efficiency caused by releasing pressure contact between a fixing member and a pressure member at a fixing part as necessary during the occurrence of paper jam.SOLUTION: In an image forming apparatus 1 forming an image on a recording medium S wound in a roll state, a fixing member 11 and a pressure member 14 are separated from each other only when a sensor 15 detects that the recording medium S is at a fixing part during the occurrence of paper jam. With this configuration, the fixing member 11 and pressure member 14 are prevented from being separated from each other when the recording medium S is not at the fixing part 10 as well.

Description

  The present invention relates to an image forming apparatus applied to a copying machine, a printer, a facsimile machine, and the like, and more particularly to an image forming apparatus that forms an image on a recording medium wound in a roll shape. Furthermore, the present invention relates to an image forming system using the image forming apparatus.

  An electrophotographic image forming apparatus in which a toner image formed on a photoreceptor is transferred onto a transfer material such as paper, and the toner image is fixed on the paper by heating and pressurizing the paper on which the toner image has been transferred in a fixing unit. doing.

  The fixing unit used in such an image forming apparatus includes a fixing member constituted by, for example, a heating roller, and a counter roller that is provided at a position facing the fixing member and rotates in pressure contact with the fixing member side. It is comprised with a pressurizing member. Then, the sheet carrying the unfixed toner image passes through the nip portion between the fixing member and the pressure member, whereby the toner image is fixed on the sheet.

  In an image forming apparatus using a normal sheet cut to a predetermined size as a recording medium, the fixing unit is in a pressing state when an operation for removing a remaining sheet when a jam occurs during sheet passing is performed. It is known that the fixing member and the pressure member are separated to release the pressure contact between the fixing member and the pressure member. Release of the pressure contact between the fixing member and the pressure member at the time of such jamming is normally performed uniformly.

  On the other hand, in recent years, in an electrophotographic image forming apparatus, a technique using a recording medium wound in a roll shape (hereinafter, roll paper) as a recording medium has been proposed (see Patent Document 1). When transporting roll paper that is continuous in the transport direction as described above, a guide section that performs side regulation on the paper feed side is provided to prevent meandering during paper transport, and a certain amount of tension is applied to the roll paper. Transport. At that time, when an abnormality occurs such that the roll paper strongly comes into contact with the guide portion or the roll paper enters the conveyance path in an oblique manner, the end of the roll paper is scratched (cracked). Starting from this scratch, there are cases where the roll paper breaks due to the tension applied to the roll paper.

JP-A-11-10970

  As described above, when the roll paper breaks during conveyance, it may not be preferable to release the pressure contact between the fixing member and the pressure member of the fixing unit during the jam processing. For example, when the pressure contact between the fixing member and the pressure member is released until there is no roll paper remaining in the fixing unit, the internal air generated due to the temperature difference in the machine is between the fixing member and the pressure member released from the pressure contact. The temperature of the fixing member and the pressure member is lowered. Then, the fixing member and the pressure member are heated again, and the printing (image forming) operation cannot be resumed until the interior of the apparatus rises to a predetermined temperature, resulting in a decrease in operating efficiency. Therefore, the conventional control that releases the pressure contact of the fixing unit uniformly when a jam occurs is not preferable in practice.

  Accordingly, an object of the present invention is to prevent a reduction in operating efficiency by releasing the pressure contact between the fixing member and the pressure member in the fixing unit as necessary when a jam occurs.

  In order to solve the above problems and achieve the object of the present invention, an image forming apparatus of the present invention is an image forming apparatus for forming an image on a recording medium wound in a roll shape, and includes a fixing unit, a sensor, and a control unit. Is provided. The fixing unit records a toner image by passing a recording medium carrying an unfixed toner image through a nip formed by a fixing member heated to a predetermined temperature and a pressure member pressed against the fixing member. Fix to media. The sensor is a sensor that detects the presence or absence of a recording medium in the fixing unit. The controller separates the fixing member and the pressure member only when the sensor detects that there is a recording medium when a jam occurs.

  An image forming system according to the present invention includes the image forming apparatus according to the present invention and a paper feeding device that supplies a recording medium to the image forming apparatus.

  The image forming apparatus and the image forming system of the present invention include a sensor that detects the presence or absence of a recording medium in the fixing unit, and controls only when the sensor detects that the recording medium is in the fixing unit when a jam occurs. The unit separates the fixing member and the pressure member. As a result, if the sensor detects that there is no recording medium in the fixing unit when a jam occurs, the fixing member and the pressure member are not separated from each other. Can be prevented.

  According to the present invention, in the image forming apparatus and the image forming system, it is possible to prevent a decrease in operating efficiency.

1 is a schematic configuration diagram of an image forming system according to an embodiment of the present invention. 1 is a schematic configuration diagram of a main part of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram showing a control system of an image forming system according to an embodiment of the present invention. 3 is a flowchart showing a control method of the image forming system according to the embodiment of the present invention.

  Hereinafter, an example of an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following examples.

<Image forming system>
FIG. 1 is a schematic configuration diagram of an image forming system 100 according to an embodiment of the present invention. The image forming system 100 includes an image forming apparatus 1, a paper feeding device 2 that supplies the roll paper S to the image forming apparatus 1, and a paper discharge device 3 that winds up the roll paper S discharged from the image forming apparatus 1. .

[1. Configuration of image forming apparatus]
First, the image forming apparatus 1 will be described. The image forming apparatus 1 forms an image on the roll paper S by electrophotography, and tandems superimposes toners of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). This is a color image forming apparatus of the type.

  As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes a conveyance unit 73, an image forming unit 40, an intermediate transfer belt 50, a secondary transfer unit 70, a fixing unit 10, and a blower device 18. The upstream sensor 15, the downstream sensor 16, the operation display unit 65, and the control unit 60 are provided.

  The conveyance unit 73 includes a plurality of conveyance rollers provided on the upstream side of the secondary transfer unit 70, and roll paper S conveyed from the sheet feeding device 2 is transferred to the secondary transfer unit 70 that is a transfer position. Convey continuously.

  The image forming unit 40 includes four image forming units 40Y, 40M, 40C, and 40K in order to form toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (Bk). .

  The first image forming unit 40Y forms a yellow toner image, and the second image forming unit 40M forms a magenta toner image. The third image forming unit 40C forms a cyan toner image, and the fourth image forming unit 40K forms a black toner image. Since these four image forming units 40Y, 40M, 40C, and 40K have the same configuration, the first image forming unit 40Y will be described as a representative here.

  The first image forming unit 40Y includes a drum-shaped photoconductor 41, a charging unit 42 arranged around the photoconductor 41, an exposure unit 43, a developing unit 44, and a cleaning device 45. . The photoreceptor 41 is rotated counterclockwise by a drive motor (not shown). The charging unit 42 applies a charge to the photoconductor 41 and uniformly charges the surface of the photoconductor 41. The exposure unit 43 performs exposure scanning on the surface of the photoconductor 41 based on image data transmitted from the outside, and forms an electrostatic latent image on the photoconductor 41.

  The developing unit 44 attaches yellow toner to the electrostatic latent image formed on the photoconductor 41. As a result, a yellow toner image is formed on the surface of the photoreceptor 41. The developing unit 44 of the second image forming unit 40M attaches magenta toner to the photoconductor 41, and the developing unit 44 of the third image forming unit 40C attaches cyan toner to the photoconductor 41. Then, the developing unit 44 of the fourth image forming unit 40K adheres black toner to the photoconductor 41.

  The toner adhered on the photoreceptor 41 is transferred to the intermediate transfer belt 50. The cleaning device 45 removes the toner remaining on the surface of the photoreceptor 41 after being transferred to the intermediate transfer belt 50.

  The intermediate transfer belt 50 is formed in an endless shape, and is rotated clockwise by a drive motor (not shown) in a direction opposite to the rotation direction of the photoconductor 41. A primary transfer portion 51 is provided at a position on the intermediate transfer belt 50 that faces the photoreceptor 41 of each of the image forming units 40Y, 40M, 40C, and 40K. The primary transfer unit 51 applies a polarity opposite to that of the toner to the intermediate transfer belt 50 to transfer the toner image formed on the photoreceptor 41 to the intermediate transfer belt 50.

  As the intermediate transfer belt 50 rotates, the toner images formed by the four image forming units 40Y, 40M, 40C, and 40K are sequentially transferred onto the surface of the intermediate transfer belt 50. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 50 to form a color image.

  A secondary transfer unit 70 is disposed in the vicinity of the intermediate transfer belt 50 and on the downstream side of the transport unit 73. The secondary transfer unit 70 includes a transfer roller pair 71 including a transfer upper roller on which the intermediate transfer belt 50 is stretched and a transfer lower roller pressed against the transfer upper roller with the intermediate transfer belt 50 interposed therebetween. .

  In the secondary transfer unit 70, the roll paper S conveyed from the conveyance unit 73 is pressed toward the intermediate transfer belt 50 by the lower transfer roller. The secondary transfer unit 70 transfers the color toner image formed on the intermediate transfer belt 50 onto the paper S sent from the transport unit 73. The cleaning unit 52 removes the toner remaining on the surface of the intermediate transfer belt 50 after the transfer to the roll paper S.

  A pre-transfer sensor 74 is provided in the vicinity of the secondary transfer unit 70 and upstream of the secondary transfer unit 70 in the sheet conveyance direction. The pre-transfer sensor 74 detects the presence of paper (roll paper S) on the upstream side of the secondary transfer unit 70.

  The fixing unit 10 includes a fixing belt 11 and a pressure roller 14 that is a pressure member. FIG. 2 shows a schematic configuration of a main part including the fixing unit 10 of the image forming apparatus 1. As shown in FIG. 2, the fixing belt 11 is composed of an endless elastic member, and is supported and stretched between a fixing roller 12 as a driving roller and a heating roller 13 as a driven roller. Note that the fixing belt 11 of the present embodiment constitutes a fixing member of the present invention.

  The fixing belt 11 is made of an elastic member in which a base layer made of PI (polyimide) is coated with PFA (tetrafluoroethylene), for example. The fixing roller 12 is formed of a cylindrical member having an outer diameter of 50 to 90 mm, and has an elastic layer having a thickness of 10 to 30 mm, for example, on the cored bar. The heating roller 13 is formed of a cylindrical member having an outer diameter of 50 to 90 mm with a halogen heater built therein, and the surface thereof is coated with PFTE (polytetrafluoroethylene).

  The fixing belt 11 is heated by the heating roller 13 being heated by the halogen heater. At this time, the fixing belt 11 is controlled to 160 ° C. to 210 ° C. The heated fixing belt 11 rotates in the clockwise direction in the drawing when the fixing roller 12 is driven to rotate.

  The pressure roller 14 is made of a cylindrical member having an outer diameter of 50 to 90 mm, and has an elastic layer made of urethane rubber or the like having a thickness of 1 to 20 mm on the core metal. A pressure mechanism is provided so as to be in pressure contact with the fixing roller 12 with the fixing belt 11 interposed therebetween. The pressure roller 14 rotates in conjunction with the fixing belt 11 that rotates. In the present embodiment, the linear velocity on the surface of the pressure roller 14 is 220 to 500 mm / s.

  In this embodiment, the pressure roller 14 is driven by the fixing belt 11, but the pressure roller 14 may be configured as a driving roller. Further, a heater for heating the pressure roller 14 may be provided.

  A nip portion 17 is formed at a portion where the fixing belt 11 and the pressure roller 14 come into contact with each other. When the roll paper S carrying the toner image passes through the nip portion 17 of the fixing unit 10, the toner is melted by the fixing belt 11 and the pressure roller 14 controlled to a predetermined temperature and fixed on the roll paper S.

  The blower 18 includes an axial fan 18a that sends out air of a desired air volume, and a nozzle portion 18b that guides the air sent from the axial fan 18a to be jetted in the vicinity of the nip portion 17. The opening at the tip of the nozzle portion 18 b is formed in an elongated shape along a direction orthogonal to the rotation direction of the fixing belt 11, and the longitudinal direction is provided so as to be substantially parallel to the nip portion 17. Thereby, air can be uniformly jetted onto the roll paper that has passed through the nip portion 17. The amount of air blown from the nozzle portion 18b can be adjusted by controlling the current value supplied to the axial fan 18a and changing the rotational speed of the axial fan 18a.

  By the way, when the roll paper S breaks in the middle of the conveyance path, the roll paper S remains in the nip portion 17 of the fixing unit 10, and the roll paper S is a synthetic paper having low heat resistance. In such a case, the roll paper S remaining in the nip portion 17 may be damaged by heat. In order to prevent this, in the present embodiment, when the jam occurs and the roll paper S remains in the nip portion 17, the fixing belt 11 and the pressure roller 14 are separated from each other, The occurrence of damage to the roll paper S can be suppressed by injecting the cooling air with the air volume corresponding to the type of the roll paper S. In the present embodiment, the air volume of the cooling air sprayed from the blower 18 can be controlled in two stages, “strong” and “medium”.

  Even when a jam occurs, it is not always necessary to spray cooling air when the roll paper S does not remain in the nip portion 17. Therefore, in the present embodiment, the presence or absence of the roll paper S in the fixing unit 10 is detected by an upstream sensor 15 and a downstream sensor 16 described later, and the control unit 60 controls the blower 18 according to the detection result. A method for controlling the blower 18 when a jam occurs will be described later.

  The upstream sensor 15 is provided in the vicinity of the nip portion 17 formed by the fixing belt 11 and the pressure roller 14 and upstream of the nip portion 17 in the sheet conveyance direction. The upstream sensor 15 detects the presence or absence of paper (roll paper S) at a position facing the upstream sensor 15. The upstream sensor 15 also serves as a tension detection unit that detects the tension of the roll paper S. Since the upstream sensor 15 also serves as a tension detection unit, space can be saved as compared with a configuration in which a tension detection unit is separately provided.

  The downstream sensor 16 is provided in the vicinity of the nip portion 17 formed by the fixing belt 11 and the pressure roller 14 and on the downstream side of the nip portion 17 in the paper transport direction. The downstream sensor 16 detects the presence or absence of paper (roll paper S) at a position facing the downstream sensor 16.

  The operation display unit 65 is a touch panel including a display such as a liquid crystal display (LCD) or an organic ELD (Electro Luminescence Display). The operation display unit 65 displays an instruction menu for the user, information about the acquired image data, and the like. Furthermore, the operation display unit 65 includes a plurality of keys, and serves as an input unit that receives input of various instructions, characters, numbers, and other data by user key operations. In the present embodiment, the user inputs the paper type of the roll paper S installed in the paper feeding device 2 set in the operation display unit 65.

  The control unit 60 operates each unit of the image forming apparatus 1 according to an instruction from the operation display unit 65 or an externally connected personal computer 120 (see FIG. 3). In particular, in the present embodiment, the control unit 60 is in contact with the fixing unit 10 according to the detection result of each sensor including the upstream sensor 15 and the downstream sensor 16 and the paper type, and is cooled by the blower 18. The point that controls the wind is characteristic. This control method will be described in detail later.

[2. Paper feeding device / paper ejection device]
Next, the paper feeding device 2 and the paper ejection device 3 will be described. The paper feed device 2 includes a roll paper installation unit 22, a transport unit 21, and a paper feed sensor 23. A roll paper main body 20 around which a desired roll paper is wound is rotatably installed in the roll paper installation unit 22. Further, the transport unit 21 includes a plurality of transport rollers, and transports the roll paper S discharged from the roll paper installation unit 22 to the image forming apparatus 1 side. For example, the paper feed sensor 23 is provided in the vicinity of a discharge port through which the roll paper S of the paper feed device 2 is discharged to the image forming apparatus 1 side, and the paper (roll paper S) at a position facing the paper feed sensor 23. The presence or absence of is detected.

  The paper discharge device 3 includes a paper discharge sensor 33, a transport unit 31, and a winding unit 32. The paper discharge sensor 33 is provided in the vicinity of the entrance of the roll paper S that is discharged from the image forming apparatus 1 side to the paper discharge apparatus 3, and indicates whether or not there is paper (roll paper S) at a position facing the paper discharge sensor 33. Detect. The conveyance unit 31 includes a plurality of conveyance rollers, and conveys the roll paper S discharged to the paper discharge device 3 to the winding unit 32 side. The winding unit 32 winds the conveyed roll paper S in a roll shape.

[3. Configuration of control system]
FIG. 3 is a block diagram showing an internal configuration of the image forming apparatus 1 constituting the image forming system 100. As shown in FIG. 3, the image forming apparatus 1 includes a control unit 60, an image processing unit 36, an image forming unit 40, an operation display unit 65, a transport unit 73, an HDD 64, a fixing unit 10, and an air blower. A device 18 and a communication unit 66 are provided.

  The control unit 60 includes, for example, a CPU (Central Processing Unit) 61, a ROM (Read Only Memory) 62 for storing programs executed by the CPU 61, and a RAM (Random Access Memory) 63 used as a work area of the CPU 61. And have. As the ROM 62, a programmable ROM that is normally electrically erasable is used.

  The control unit 60 is connected to the image processing unit 36, the image forming unit 40, the operation display unit 65, the conveyance unit 73, the HDD 64, the fixing unit 10, the sensors including the upstream sensor 15 and the downstream sensor 16, and the communication unit 66. Connected via the bus 107, the entire image forming apparatus 1 is controlled. Further, the control unit 60 controls each unit of the paper feeding device 2 and the paper discharging device 3 via the communication unit 66. That is, in the present embodiment, the control unit 60 controls the entire image forming system 100.

  Image data transmitted from a PC (personal computer) 120, which is an example of an external device connected to the image forming apparatus 1, is sent to the image processing unit 36 and is subjected to image processing in the image processing unit 36. Under the control of the control unit 60, the image processing unit 36 performs image processing such as shading correction, image density adjustment, and image compression on the received image data as necessary. Further, the image forming unit 40 receives the image data processed by the image processing unit 36 under the control of the control unit 60 and forms an image on the roll paper S based on the image data.

  In addition, the user inputs the type (paper type) of the roll paper S on the operation display unit 65. In the present embodiment, the control unit 60 controls the amount of cooling air ejected from the blower 18 when a jam occurs, according to the paper type of the roll paper S input from the operation display unit 65.

  The communication unit 66 is a communication interface for connecting to a network to which each device constituting the image forming system 100 is connected. For example, the image forming apparatus 1 performs serial communication with the paper feeding device 2 and the paper discharging device 3 via the communication unit 66.

[4. Method for controlling image forming system]
FIG. 4 is a flowchart showing a control method of the image forming system 100 of the present embodiment. A control method of the image forming system of this embodiment will be described with reference to FIG. Note that the control unit 60 of the image forming apparatus 1 implements the processing of the flowchart shown in FIG. 4 when the CPU 61 executes a program stored in the ROM 62.

  First, in the present embodiment, prior to the start of printing, the user inputs the paper type of the roll paper S constituting the roll paper main body 20 set in the paper feeding device 2 from the operation display unit 65. The input of the paper type in this embodiment is performed by the user selecting from among a plurality of paper types (for example, plain paper, synthetic paper, thick paper, thin paper, etc.) displayed on the operation display unit 65, for example.

  When printing is started, the user presses a print start switch provided in or near the operation display unit 65 (step S1). As a result, the control unit 60 starts printing by operating the image forming system 100 by controlling the respective units of the image forming apparatus 1, the sheet feeding apparatus 2, and the sheet discharging apparatus 3 (step S2). When printing is started, the roll paper S is conveyed from the paper feeding device 2 to the image forming apparatus 1 with a certain tension applied, and the toner image is transferred to the roll paper S in the secondary transfer unit 70. Then, the roll paper S to which the toner image is transferred passes through the nip portion 17 of the fixing unit 10, so that the toner image is fixed to the roll paper S. The roll paper S on which the image is formed in this way is conveyed to the paper discharge device 3 side and is taken up by the winding unit 32 of the paper discharge device 3 as needed.

  In parallel with the above printing operation, the control unit 60 determines that all the sensors are “paper” based on the detection results of all the sensors of the paper feed sensor 23, the pre-transfer sensor 74, the upstream sensor 15, the downstream sensor 16, and the paper discharge sensor 33. It is determined whether or not “present” is detected (step S3). When all the sensors detect “paper present” in step S3 (in the case of “YES” in step S3), the control unit 60 continues printing (step S4).

  On the other hand, if at least one of all the sensors detects “no paper” in step S3 (that is, if “NO” is determined in step S3), the control unit 60 then feeds the paper feed sensor 23. Determines whether or not “paper present” is detected (step S5). When the paper feed sensor 23 detects “paper present” in step S5 (when “YES” is determined in step S5), it means that “no paper” is detected by a sensor other than the paper feed sensor 23. The roll paper S is broken somewhere. Therefore, if “YES” is determined in step S5, the control unit 60 determines that a jam that causes the roll paper S to break has occurred, immediately stops the operation of the image forming system 100, and stops printing (step S6). ).

  When the paper feed sensor detects “no paper” in step S5 (when “NO” is determined in step S5), the control unit 60 then sequentially sets “no paper” at predetermined time intervals. It is determined whether or not to detect (step S7).

  When the roll paper main body 20 installed in the paper feeder 2 is lost, the end of the roll paper S reaches the paper feed sensor 23, the pre-transfer sensor 74, the upstream sensor 15, the downstream sensor 16 and the paper discharge sensor 33 in order. pass. When the end of the roll paper S has passed, the paper feed sensor 23, the pre-transfer sensor 74, the upstream sensor 15, the downstream sensor 16, and the paper discharge sensor 33 sequentially detect “no paper” at predetermined time intervals. I will do it. Therefore, when each sensor detects “no paper” in order at predetermined time intervals from the upstream side to the downstream side in the paper conveyance direction (in the case of “YES” in step S7), the control unit 60 It is determined that the roll paper S is finished, and the operation of the image forming system 100 is finished. Here, the “predetermined time interval” is determined by the transport speed of the roll paper S and the distance between two sensors arranged at adjacent positions.

  When the sensors do not sequentially detect “no paper” at a predetermined time interval from the upstream side to the downstream side in the paper conveyance direction in step S7 (when “NO” is determined in step S3), the control unit 60 has a jam. The operation of the image forming system 100 is immediately stopped and printing is stopped (step S6).

  After stopping printing in step S6, the control unit 60 determines whether or not at least one of the upstream sensor 15 and the downstream sensor 16 detects “paper present” (step S8). When at least one of the upstream sensor 15 and the downstream sensor 16 detects “paper present” in step S8 (in the case of “YES” in step S8), the control unit 60 controls the pressure roller 14. After being separated from the fixing belt 11, the pressure contact between the fixing belt 11 and the pressure roller 14 is released (step S9).

  After releasing the pressure contact between the fixing belt 11 and the pressure roller 14 in step S9, the control unit 60 determines whether “synthetic paper” is selected as the paper type of the roll paper S (step S10). The term “synthetic paper” as used herein refers to paper that is manufactured using synthetic resin as a main raw material and is less susceptible to heat than plain paper. The paper type of the roll paper S is input in advance from the operation display unit 65 or the personal computer 120 by the user.

  When it is determined in step S10 that “synthetic paper” is selected (in the case of “YES” in step S10), the control unit 60 determines that the amount of cooling air ejected from the blower 18 is “strong”. The blower 18 is controlled so as to become (step S11). If it is determined in step S10 that “synthetic paper” is not selected (in the case of “NO” in step S10), the control unit 60 determines that the amount of cooling air ejected from the blower 18 is “medium”. The blower 18 is controlled so as to become (step S12).

  In step S11 and step S12, the cooling air is jetted from the blower 18 to cool the roll paper S remaining in the vicinity of the fixing unit 10 when a jam occurs, so that the roll paper S is damaged by the heat of the fixing unit 10. Can be suppressed. In addition, when the roll paper S is a synthetic paper, the roll paper S remaining in the fixing unit 10 is quickly cooled by setting the air volume of the cooling air to “strong”, and the roll has low heat resistance against heat. The occurrence of damage to the paper S is suppressed. On the other hand, when the roll paper S is not a synthetic paper and is a paper type having a certain degree of heat resistance, by setting the air volume of the cooling air to “medium”, while preventing the occurrence of damage to the roll paper S due to heat, It is possible to prevent the inside of the apparatus from being excessively cooled.

  In step S11 or step S12, after the cooling air is jetted from the blower 18 and the roll paper S is cooled, the user performs a so-called jam process such as removing the roll paper S remaining in the apparatus ( Step S13).

  On the other hand, when both the upstream sensor 15 and the downstream sensor 16 detect “no paper” in step S8 (in the case of “NO” in step S8), the fixing unit 10 includes the roll paper S. Is not left. For example, when the roll paper S is broken upstream of the upstream sensor 15 in the paper conveyance direction, the roll paper S downstream from the break position in the paper conveyance direction is discharged from the break position until the printing is stopped immediately after the break. It may be pulled to the third side and conveyed to the downstream side of the downstream sensor 15 in some cases. In such a case, when a jam occurs, the roll paper S does not remain between the fixing belt 11 and the pressure roller 14 of the fixing unit 10, and both the upstream sensor 15 and the downstream sensor 16 indicate “no paper”. Detect.

  If “NO” is determined in step S8, the control unit 60 performs control so as to maintain the state where the fixing belt 11 and the pressure roller 14 are in pressure contact with each other (step S14). Thereafter, the control unit 60 controls the blower 18 so that the cooling air is kept off (stopped) (step S15). Next, the user performs so-called jam processing such as removing the roll paper S that has been broken in the apparatus (step S13).

  In the present embodiment, when a jam occurs, the roll paper S breaks in the middle and no roll paper S remains between the fixing belt 11 and the pressure roller 14 of the fixing unit 10. The pressure contact with the roller 14 is not released. For this reason, by separating the fixing belt 11 and the pressure roller 14, the in-machine air generated by the temperature difference in the apparatus passes between the separated fixing belt 11 and the pressure roller 14, and the temperature of the fixing unit 10 is increased. There is no cooling. Further, at this time, the cooling air is not injected from the blower 18. Thus, in this embodiment, the fixing unit 10 is prevented from being unnecessarily cooled until the roll paper S does not remain between the fixing belt 11 and the pressure roller 14 when a jam occurs. Can do.

  After completion of the jam processing in step S13, the control unit 60 determines whether or not all sensors detect “no paper” (step S16). In step S16, if at least one of all the sensors detects “paper present” (in the case of “NO” in step S16), the control unit 60 causes the operation display unit 65 to break the roll when a jam occurs. The user is informed of where the paper S remains. The user performs jam processing again according to the instruction of the operation display unit 65 (step S13). Steps S13 and S16 are repeated until there is no remaining paper in the apparatus.

  In step S16, when “no paper” is detected by all the sensors (in the case of “YES” in step S16), the control unit 60 informs the user that printing can be resumed on the operation display unit 65. Inform. Then, after confirming the resumable display on the operation display unit 65, the user presses the switch for resuming printing (step S17). As a result, the image forming system 100 is activated again and printing is resumed.

  As described above, in this embodiment, when the roll paper S breaks, only when the roll paper S remains between the fixing belt 11 and the pressure roller 14 when a jam occurs, the fixing belt 11 is added. The pressure contact with the pressure roller 14 is released, and cooling air is injected. Thereby, it is possible to perform jam processing without unnecessarily cooling the fixing unit 10. For this reason, if the pressure contact between the fixing belt 11 and the pressure roller 14 is not released, a decrease in the temperature of the fixing unit 10 can be suppressed. The time until heating to temperature can be shortened. Thereby, the image forming apparatus 1 can be returned to a printable state in a short time, and the operating rate can be improved.

  In this embodiment, the presence or absence of the roll paper S between the fixing belt 11 and the pressure roller 14 is determined from the detection results of the two sensors, the upstream sensor 15 and the downstream sensor 16. Any configuration that can detect the presence or absence of the roll paper S between the belt 11 and the pressure roller 14 may be used. For example, the presence or absence of the roll paper S may be detected by one of the upstream sensor 15 and the downstream sensor 16.

  As described above, when the roll paper S is ruptured, the roll paper S that is on the downstream side in the paper conveyance direction from the rupture position immediately after the rupture until the printing is stopped is pulled and conveyed to the paper discharge device 3 side. The Therefore, for example, when the roll paper S breaks between the nip portion 17 and the downstream sensor 16 of the fixing unit 10, the roll paper S on the upstream side in the paper transport direction from the break position is between the fixing belt 11 and the pressure roller 14. Even if it remains, there is a high possibility that the downstream sensor 16 will detect “no paper”. For this reason, when the presence or absence of the roll paper S in the fixing unit 10 is determined by one sensor, the upstream sensor 15 is preferably used.

  The pre-transfer sensor 74 may be the upstream sensor 15 and the paper discharge sensor 33 may be the downstream sensor 16 to determine the presence or absence of the roll paper S between the fixing belt 11 and the pressure roller 14.

  In the present embodiment, the upstream sensor 15 and the downstream sensor 16 are disposed in the vicinity of the fixing unit 10, so that the presence or absence of the roll paper S remaining between the fixing belt 11 and the pressure roller 14 when a jam occurs. Can be detected more accurately.

  Further, in the present embodiment, in step S10 in FIG. 4, the air volume of the cooling air is controlled to be “strong” or “medium” depending on whether or not the paper type of the roll paper S is synthetic paper. The adjustment of the air volume is not limited to this. For example, when the roll paper S is thick paper that is resistant to heat, the cooling air is maintained in a stopped state, or the air volume of the cooling air is set to “weak” and the air flow is set to “weak”. The device 18 may be controlled. As described above, the air blower 18 may be configured to be capable of injecting an air volume according to the heat capacity of the paper type of the roll paper S, and various changes can be made.

  The air blower 18 in the image forming apparatus 1 of the present embodiment is provided to cool the roll paper S remaining between the fixing belt 11 and the pressure roller 14 that are separated when a jam occurs. It can also be used when separating the roll paper S from the fixing belt 11. During the printing operation, the roll paper S that has passed through the nip 17 of the fixing unit 10 may be wound around the fixing belt 11 due to the adhesive force of the toner. In order to prevent this, for example, the air blower 18 is configured so that the air flow can be switched between three levels of “strong”, “medium”, and “weak”. Inject air of air volume. By doing so, during the printing operation, a weak wind is jetted from the blower 18 between the roll paper S that has passed through the nip portion 17 of the fixing unit 10 and the fixing belt 11, and the roll paper S is peeled off from the fixing belt 11. It becomes easy. Thereby, it is possible to prevent the roll paper S from being caught on the fixing belt 11 side.

  In this way, when air of “weak” air volume is ejected from the blower 18 during the printing operation in order to separate the roll paper S from the fixing belt 11, in step S <b> 15 of FIG. 4, the blower 18. What is necessary is just to stop the air (cooling wind) injected from.

  As described above, the color image forming apparatus has been described as an example in the present embodiment, but the present invention can also be applied to a monochrome image forming apparatus. Further, the image forming apparatus is not limited to a copying machine, but may be a printer, a facsimile, or a multifunction machine having a plurality of functions.

  Further, in this embodiment, the fixing unit 10 is a belt fixing method using the fixing belt 11 as a fixing member. However, a roller fixing method using only a fixing roller as a fixing member is the same as in this embodiment. The configuration can be applied. Also, the heating means for the fixing member is not limited to a heater such as a halogen lamp, and an induction heating method can also be adopted.

  In this embodiment, the user inputs the paper type from the operation display unit 65. However, the paper type may be input by the external personal computer 120. In addition, various modifications can be made without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Paper feeding apparatus, 3 ... Paper discharge apparatus, 10 ... Fixing part, 11 ... Fixing belt, 14 ... Pressure roller, 15 ... Upstream sensor, 16 ... Downstream sensor, 17 ... Nip part , 18 ... Blower, 22 ... Roll paper installation unit, 23 ... Paper feed sensor, 32 ... Winding unit, 33 ... Paper discharge sensor, 42 ... Charging unit, 43 ... Exposure unit, 44 ... Development unit, 45 ... Cleaning device , 50 ... intermediate transfer belt, 52 ... cleaning unit, 60 ... control unit, 65 ... operation display unit, 70 ... secondary transfer unit, 74 ... sensor before transfer, 100 ... image forming system

Claims (6)

An image forming apparatus for conveying a recording medium wound in a roll and forming an image on the recording medium,
The recording medium carrying an unfixed toner image is passed through a nip formed by a fixing member heated to a predetermined temperature and a pressure member pressed against the fixing member, and the toner image is recorded. A fixing unit for fixing to a medium;
A sensor for detecting the presence or absence of the recording medium in the fixing unit;
An image forming apparatus comprising: a controller that separates the fixing member and the pressure member only when the sensor detects that the recording medium is present when a jam occurs during conveyance of the recording medium. The image forming apparatus according to claim 1, wherein the sensor is disposed upstream of the fixing unit with respect to a conveyance direction of the recording medium. The sensor is disposed on the upstream side of the fixing unit with respect to the conveyance direction of the recording medium, and an upstream sensor that detects the presence or absence of the recording medium, and the fixing with respect to the conveyance direction of the recording medium. And a downstream sensor for detecting the presence or absence of the recording medium.
The control unit separates the fixing member and the pressure member only when it is detected that the recording medium is present in at least one of the upstream sensor and the downstream sensor when a jam occurs. The image forming apparatus described in 1. A blower for blowing cooling air in the vicinity of the nip portion of the fixing unit;
The image according to any one of claims 1 to 3, wherein the control unit adjusts an amount of cooling air to be blown when the fixing member and the pressure member are separated from each other according to the type of the recording medium. Forming equipment. 5. The image formation according to claim 4, wherein, when a jam occurs, when the upstream sensor and the downstream sensor detect that the recording medium is not present, the control unit stops blowing cooling air in the blowing device. apparatus. An image forming apparatus for forming an image on a roll-shaped recording medium,
The recording medium carrying an unfixed toner image is passed through a nip formed by a fixing member heated to a predetermined temperature and a pressure member pressed against the fixing member, and the toner image is recorded. A fixing unit for fixing to a medium;
A sensor for detecting the presence or absence of the recording medium in the fixing unit;
An image forming apparatus comprising: a control unit that separates the fixing member and the pressure member only when the sensor detects that the recording medium is present when a jam occurs;
An image forming system comprising: a paper feeding device that supplies the recording medium to the image forming apparatus.

Images