JP5016818B2 - Image forming apparatus - Google Patents

Description

The present invention is an electrostatic recording method, or related to an electrophotographic image forming apparatus.

  For example, in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, an electrostatic latent image is formed on a photosensitive drum, and the electrostatic latent image is developed as a toner image by a developing device. The image is transferred onto a recording material (hereinafter referred to as a transfer material) by a transfer device. The transfer material is passed through the nip portion of the image heating and fixing device (hereinafter referred to as paper passing) to apply heat and pressure to the toner image to heat and fix the toner image on the recording material.

  As the image heat fixing device (hereinafter abbreviated as a fixing device), a heat roller type fixing device or a film heating type fixing device is used.

  As described in Patent Document 1, a heat roller type fixing device includes a halogen lamp (heating means), a fixing roller (heated rotating body) heated by the halogen lamp, and a nip portion ( A pressure roller (pressure rotator) for forming a fixing nip portion). The toner image is heated and fixed on the transfer material by applying the heat of the halogen lamp and the nip pressure to the toner image on the transfer material while nipping and transferring the transfer material at the nip portion.

  As described in Patent Documents 2 and 3, the film heating type fixing device is in contact with a ceramic heater (heating means), a fixing film (heating rotator) that slides in contact with the ceramic heater, and the fixing film. And a pressure roller (pressure rotator) for forming a nip portion. The toner image is heated and fixed on the transfer material by applying heat and nip pressure of a ceramic heater to the toner image on the transfer material while nipping and transferring the transfer material at the nip portion.

  In the heat roller type fixing device, in order to control the temperature of the fixing roller, at least one thermistor (temperature detecting means) is arranged close to or in contact with the outer peripheral surface of the fixing roller. Based on the temperature detected by the thermistor, the temperature control circuit performs energization control, that is, temperature control for the halogen lamp.

  In the film heating type fixing device, at least one thermistor (temperature detecting means) is disposed in contact with the ceramic heater in order to control the temperature of the fixing film. Based on the temperature detected by the thermistor, the temperature control circuit performs energization control, that is, temperature control on the heating element.

  In each of the fixing devices, it is necessary to prevent the surface temperature of the fixing film and the fixing roller from excessively rising when the energization control for the ceramic heater or the halogen lamp becomes impossible due to any abnormality. Therefore, safety elements such as a thermo switch and a thermal fuse are connected in series to the ceramic heater and the halogen lamp. Then, when the surface temperature of the heat resistant film or the fixing roller becomes abnormally high, the power supply to the ceramic heater or the halogen lamp is cut off by the safety element.

By the way, in the case of a fixing device in which the maximum size of the recording material to be passed through the nip portion is compatible with A3 size paper, it is generally possible to pass recording materials of the following sizes in addition to A3 size. Is. Recording materials of each size other than A3 size include recording materials of various sizes such as B4, A4 width, A4 length, A5 width, A5 length, B5 width, B5 length, western envelope, postcard and the like. In this case, the temperature detecting means is generally arranged in an area through which the recording material of the minimum size surely passes in order to detect the temperature of the area (sheet passing portion) through which the recording material passes in the nip portion. is there. In addition, a safety element such as a thermo switch is generally arranged in a region through which the recording material passes so that it operates only when the temperature control circuit runs out of control and the energization control for the heating element cannot be normally performed. is there.
JP-A-5-35138 JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878

In the case of an image forming apparatus having a so-called multi-tray paper feed port, the lateral width orthogonal to the recording material conveyance direction can be arbitrarily changed by the end regulating plate according to the size of the recording material. The following can happen: Also the recording material size is passed through the nip portion is within the guaranteed range, the user is aware of the state, for example, end regulating plate of the multi-tray sheet feed port than the width, such as envelopes and postcards are open larger than the proper width There may not be. In addition, when an envelope, a postcard, or the like is moved toward one side of the end regulating plate and passed through the nip portion, the envelope, the postcard, or the like passes through an inappropriate position that deviates from the position where it should originally pass. In this case, the following inconvenience may occur.

  First, since the envelope and postcard do not pass through the position of the leading and trailing edge detection sensor provided on the recording material introduction port side of the nip portion, a detection signal cannot be obtained from the leading and trailing edge detection sensor, and a paper jam such as a delay jam occurs. Inconvenience occurs. Next, since the envelope and the postcard do not pass through the thermistor position, the temperature control of the passage portion of the envelope and the postcard cannot be performed, resulting in inconvenience of fixing failure. Lastly, the area through which envelopes and postcards pass becomes a non-sheet-passing area, resulting in high temperatures, resulting in inconveniences such as deterioration of the elastic layer constituting the pressure roller, malfunction of the thermo switch, and cracking of the heater. Occur.

Therefore, an object of the present invention is to automatically move the regulating plate of the paper feeding unit when the conveyance position of the recording material is inappropriate, thereby moving the recording material placed on the paper feeding unit in the width direction of the recording material. An object of the present invention is to provide an image forming apparatus in which the center is moved in the width direction so as to meet the conveyance reference .

The configuration of the image forming apparatus according to the present invention for achieving the above object is
An image forming apparatus set to convey a recording material in accordance with a conveyance reference at the center in the width direction,
An image forming unit for forming an image on a recording material;
A paper feeding unit having a movable regulating plate that regulates an end portion in the width direction of the recording material, and a recording material to be conveyed to the image forming unit;
A heating rotary member, a heating means for heating the heating rotating body, anda pressure rotating body to form a nip portion in contact with the heating rotating body, a recording medium one sandwiched and conveyed matter in the nip Fixing means for heating and fixing the image formed on the recording material to the recording material;
In an image forming apparatus having
First temperature detection means for detecting the temperature at or near the conveyance reference, and at least one second temperature detection for detecting the temperature at or near the longitudinal end of either the heating rotator and the heating means. And the temperature of the heating rotating body and any one of the heating means outside the conveyance area of the minimum size of the recording material conveyed by the conveyance reference and closer to the conveyance reference by the second temperature detection means. Any one of the first temperature detecting means, the second temperature detecting means, and the third temperature detecting means has a third temperature detecting means for detecting and a drive source for driving the regulating plate . When it is determined that the transport position of the recording material is inappropriate based on the detected value, the drive source so that the center in the width direction of the recording material placed on the paper feeding unit matches the transport reference Move the restriction plate by It said that the cell.

According to the present invention, when the conveyance position of the recording material is inappropriate, the recording material placed on the paper feeding unit is moved in the center in the width direction by automatically moving the regulation plate of the paper feeding unit. It is possible to provide an image forming apparatus that is moved in the width direction so as to meet the conveyance reference .

Hereinafter, the present invention will be described in detail with reference to the drawings.
[Reference example]

(1) Example of Image Forming Apparatus Figure 1 is a block schematic drawing of an example engaging Ru images forming apparatus of the present invention. This image forming apparatus is a laser printer (LBP) using an electrophotographic process.

  Reference numeral 3 denotes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image carrier. The photosensitive drum 3 rotates clockwise as indicated by an arrow, and the outer peripheral surface (surface) is uniformly charged by a roller charger 4 as a charging unit during the rotation. The uniformly charged surface of the photosensitive drum 3 is scanned and exposed through a mirror 2 with a laser beam 1a that is ON / OFF controlled in accordance with target image information by a scanner unit 1 as an image exposure unit. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 3. The electrostatic latent image is visualized as a toner image with toner (developer) by a developing device 5 as a developing means.

On the other hand, a transfer material (weighing 64 to 128 g) P as a recording material is sent out from either one of the paper feed cassette 11 and the multi-tray paper feed port (paper feed unit (hereinafter abbreviated as multi-tray) ) 23. A transfer material P having a certain size is stacked and stored in the paper feed cassette 11. The transfer material P is separated one by one by the paper feed roller 13 and the separation roller pair 13 a and is sent out from the paper feed cassette 11. The transfer material P is reversed by the U-turn sheet path 13 b and conveyed to the pair of registration rollers 15 along the upper and lower guides 14. The multi-tray 23 is configured so that the regulation of the lateral width can be arbitrarily changed according to the size of the transfer material P. In the multi-tray 23, the transfer material P is separated and fed one by one by the paper feed roller 22 and conveyed to the registration roller 15. The registration roller 15 conveys the transfer material P to a transfer portion that is a contact nip portion between the photosensitive drum 3 and the transfer roller 7 so as to be synchronized with the leading edge of the toner image formed on the photosensitive drum 3. A paper feed sensor (not shown) is installed in the vicinity of the registration roller 15, and the paper feed state, jam, and transfer material length are detected by this paper feed sensor.

The transfer material P conveyed to the transfer portion is given a charge of the opposite polarity to the toner from the transfer roller 7 from the back side. As a result, the toner image formed on the photosensitive drum 3 is transferred onto the transfer material P. The above is the configuration of the image forming unit.

The transfer material P onto which the toner image has been transferred is conveyed to an image heating fixing device (fixing means (hereinafter abbreviated as a fixing device) ) 18 by a conveyance guide 16 and a conveyance roller 17. In the fixing device 18, the unfixed toner image on the transfer material P is melted and fixed as a recorded image on the transfer material with heat and pressure and fixed.

  After the toner image is fixed, the transfer material P is guided to the U-turn sheet path 19a side by the flapper 19 and discharged onto the first discharge tray 20 when the image surface downward mode discharge is designated. When discharge in the image surface upward mode is specified, the flapper 19 guides the straight sheet path 19b to the second discharge tray 21 and discharges it.

  Toner, paper dust and the like remaining on the surface of the photosensitive drum 3 at the time of transfer are removed by a cleaning device 8 as a cleaning means, and the photosensitive drum is used for the next image formation.

Here, in the image forming apparatus of this reference example , the conveyance reference of the transfer material P is the central reference in all conveyance paths. This central reference will be described in section (3) . Further, the A3 size transfer material P can be transported with the short side at the front end in the entire transport path. The photosensitive drum 3, the roller charger 4, the developing device 5, and the cleaning device 8 are integrated to form a process cartridge 10. The process cartridge 10 is detachably attached to the image forming apparatus main body.

(2) Fixing device 18
FIG. 2 is a schematic cross-sectional side view of an example of the fixing device 18. The fixing device 18 is a film heating type fixing device.

  31 is a heater unit. The heater unit 31 includes a fixing film (hereinafter abbreviated as a film) 27 as a heating rotator, a film guide (hereinafter abbreviated as a guide) 28 as a support member, a reinforcing sheet metal 29 as a reinforcing member, It is an assembly body with the ceramic heater 34 as a means.

  The film 27 has a primer layer made of fluororesin and carbon on the surface of a cylindrical polyimide film having a thickness of 50 μm, and has a fluororesin layer made of PTFE, PFA or the like as a silicifying layer on the surface of the primer layer. The guide 28 is made of a heat-resistant resin such as PPS or liquid crystal polymer, and has a substantially semicircular cross section. A ceramic heater (hereinafter abbreviated as a heater) 34 is supported in a groove provided on the lower surface of the guide 28. A film 27 is loosely fitted on the guide 28. Both ends of the film 27 and both ends of the reinforcing sheet metal 29 disposed on the guide 28 are held by a flange member (not shown). This flange member is supported by a device side plate pair (not shown).

  Reference numeral 30 denotes a pressure roller as a pressure rotator. The pressure roller 30 has an elastic layer 33 made of silicone rubber, fluorine rubber or the like around a cored bar 32 made of aluminum, iron or the like. The pressure roller 30 has both ends of a cored bar 32 supported by a pair of apparatus side plates so as to be rotatable. Then, the heater unit 31 and the pressure roller 30 are brought into pressure contact with the film 27 fitted on the guide 28 at a position facing the surface of the heater 34 (the surface on the film 27 side) by a pressing means (not shown). A nip portion N is formed between the film and the pressure roller.

  The heater 34 has a substrate 24 made of alumina, for example. The substrate 24 is a member elongated in the width direction perpendicular to the transfer direction of the transfer material P. On the surface of the substrate 24, an energization heating element 25 made of a silver alloy and an energization electrode (not shown) are formed by screen printing or the like. Further, the energization heating element forming surface is covered with a thin glass protective layer 26 for protection.

  Four thermistors 41, 42, 43, and 44 that are temperature detection means and a thermo switch 45 that is a safety element are provided on the back surface (the surface opposite to the film 27) of the heater 34.

  In the fixing device 18, the pressure roller 30 is rotationally driven in the direction of the arrow by a rotation control system (not shown). As the pressure roller 30 is driven to rotate, the film 27 receives the rotational force from the pressure roller via the nip portion N and rotates.

  In the rotating state of the pressure roller 30 and the film 27, the heater 34 is energized from the AC energization control circuit (hereinafter referred to as AC line) 36 to the energization heating element 25 through the energization electrode. As a result, the energization heating element 25 generates heat in the heater 34 and the entire heater including the substrate 24 and the glass protective layer 26 is rapidly heated. The temperature of the heater 34 is detected by the four thermistors 41 to 44 arranged on the back surface of the substrate and is input to a DC controller (hereinafter referred to as CPU) 37 as a control means. The CPU 37 controls driving of the heater by the AC line 36 so that the temperature of the heater 34 detected by each of the thermistors 41 to 44 is maintained at a substantially constant temperature (fixing temperature). That is, the energization of the energization heating element 25 from the AC line 36 is controlled so that the temperature of the heater 34 is maintained at a substantially constant temperature.

  The transfer material P carrying the unfixed toner image T in a state where the heater 34 is controlled to be heated to a constant temperature is introduced into the nip portion N. The transfer material P is nipped and conveyed at the nip portion N, and is heated and pressed during the conveyance process, whereby the unfixed toner image T is heated and fixed on the transfer material. Then, the transfer material P exiting the nip portion N is discharged toward the flapper 19 (FIG. 1).

(3) Description of the thermistors 41 to 44 and the thermo switch 45 FIG. 3 shows the thermistors 41 to 44 and the thermo switch 45 on the heater, the transfer material P conveyed from an appropriate position by the multi-tray 23, and the transfer material. It is explanatory drawing of the temperature distribution when passing the nip part N. FIG.

The longitudinal width of the transfer material P conveyed by the paper feed roller 22 of the multi-tray 12 is 76 mm. This transfer material P is the minimum paper size printed by the image forming apparatus shown in this reference example . Here, the longitudinal width of the transfer material P refers to the length in the direction parallel to the width direction perpendicular to the transport direction (the longitudinal direction of the nip portion N) on the surface of the transfer material. A thick broken line indicates a sheet passing reference serving as a transport reference when the transfer material P is fed. In this reference example , the sheet passing reference (conveyance reference) is a central reference that matches the center in the longitudinal direction of the nip portion N with the center between the end portions of the transfer material P along the longitudinal direction of the nip portion. A thin broken line indicates a passing portion of an end portion (hereinafter referred to as a paper edge) of the longitudinal width of the transfer material P.

  Reference numerals 40a and 40b denote transfer material regulating plates (hereinafter referred to as regulating plates) of the multi-tray 23. When the restricting plates 40a and 40b are each opened to the maximum, the restricting plates 40a and 40b can move 160 mm from the sheet passing reference, and can feed the transfer material P having a maximum of 320 mm. Reference numeral 46 denotes a heat generation area of the heater 34. The longitudinal width of the heating resistor 25 (FIG. 2) is 320 mm.

In the present reference example , the thermistor (first temperature detecting means) 42 detects the sheet passing reference or a temperature in the vicinity thereof in the heat generation region 46 of the heater 34. Further, the thermistors (second temperature detecting means) 41 and 44 detect the temperature at the longitudinal end portion or in the vicinity thereof. Further, a thermistor (third temperature detecting means) 43 detects the temperature outside the minimum size sheet passing area (sheet passing portion) of the transfer material P and closer to the sheet passing reference than the thermistor 44. That is, for the thermistors 41 to 44 and the safety element 45, in order to define the longitudinal position of the heat generating area 46 of the heater 34, the sheet passing reference is set to ± 0, and the thermistor 42 is set to a position +20 mm as viewed from the sheet passing reference. The switch 45 is installed at a position of −20 mm. As for the thermistor 42 and the thermo switch 45, if the transfer material P is passed through from the proper position, the positions of +20 mm and −20 mm must be installed at positions where the transfer material passes through the paper passing area (paper passing portion). Yes. Further, the thermistor 41 is installed at a position of −120 mm, and the thermistor 44 is installed at a position of +140 mm as viewed from the sheet passing standard. The thermistor 43 is installed at a position of +60 mm.

  The thermistor 41 is installed at a position where the peak temperature in the non-sheet passing region (non-sheet passing portion) can be accurately measured when the transfer material P having a length of about 220 mm is fed from the multi-tray 23 as shown in FIG. It is. The thermistor 43 is installed at a position where the peak temperature in the non-sheet passing region can be accurately measured when a transfer material (not shown) having a longitudinal width of about 100 mm is fed. The thermistor 44 is installed at a position where the peak temperature in the non-sheet passing region can be accurately measured when a transfer material (not shown) having a longitudinal width of about 260 mm is fed.

  Each thermistor 41 to 44 is connected to the CPU 37, and the thermo switch 45 is connected to the AC line 36. The thermistor 42 is used to keep the heater 34 at a constant temperature, transmits the detected resistance value to the CPU 37, and drives the heater ON / OFF by the AC line 36 so as to reach a predetermined temperature. The thermo switch 45 is installed in order to make an emergency stop when the CPU 37 is energized with sudden overcurrent such as runaway, and the connection is cut off at 250 ° C. and the energization of the heater 34 is stopped.

  If the transfer material P is set at an appropriate position in the multi-tray 23, as shown in FIG. 3, the thermo switch 45 and the thermistor 42 for controlling the temperature control enter the sheet passing area. In such a case, the thermistors 41, 43, and 44 have desired values, and the temperature distribution when the temperature control temperature of the thermistor 42 is 180 ° C. is as shown in the lower graph of FIG. The sheet passing area is of course 180 ° C., but the temperature of the non-sheet passing area is increased at the same time as the heater 34 generates heat, and the temperature of the thermistor 43 is detected at about 230 ° C. Detects about 215 ° C for heat dissipation from the end. This temperature varies depending on the sheet passing interval and the temperature control temperature. Thus, if each thermistor 41-44 is a desired appropriate temperature, CPU37 will complete a job normally.

  However, as shown in FIG. 5, when the transfer material P is not set at an appropriate position and is in a paper passing state in which it is set near the right end in the transport direction (denoted as NG paper A), the thermistor 41. The detected temperatures of .about.44 are as follows. The detected temperature of the thermistor 41 is extremely lower than a desired value, and the thermistor 42 performing the temperature adjustment control is controlled to a temperature of 180 ° C. at the non-sheet passing portion. More than 20 ° C. In this case, the CPU 37 determines that the detected temperatures of all the thermistors 41 to 44 are lower than the detected temperatures of the corresponding thermistors 41 to 44 when the transfer material P having the same size is set at an appropriate position. It is determined that the sheet passing is abnormal, that is, the conveyance position is inappropriate. This determination can be made instantaneously with one sheet passing. In this case, misprinting occurs, the image forming apparatus can be stopped without failure of the fixing device, and the user can be prompted to change the transfer material P to an appropriate position. When the thermistor 43 is a non-sheet passing portion, any situation can be handled as described above.

  Further, the transfer material P is not set at an appropriate position, and the thermistor 42 is a sheet passing area, and is set to the right by several tens of mm with respect to the conveying direction (referred to as NG sheet B). The thermistor 43 detects a temperature lower than a desired value. In such a case, the detected temperatures of the thermistor 41 and the thermistor 44 are too far away from the end of the transfer material, and it is difficult to detect that the transport position is improperly instantaneous with only the thermistor 41 and the thermistor 44. In this case, the CPU 37 detects that the detected temperature of the thermistor 43 is lower than the detected temperature of the corresponding thermistor 43 when the transfer material P having the same size is set at an appropriate position. Judge that the position is inappropriate. This determination can also be made instantaneously with one sheet passing. At this time, the CPU 37 performs control to adjust the feeding interval of the transfer material P to the nip portion N so that the temperature of the heater 34 does not exceed 230 ° C. from the monitor value of the thermistor 43. In other words, by controlling the drive of the rotational drive system of the paper feed roller 22 to increase the throughput, it is possible to prevent the fixing failure of the unfixed toner image and the fixing device failure and complete the job.

  Further, when the thermistor 42 is in the sheet passing region and the transfer material is set to the left as shown in FIG. 7 (denoted as NG sheet passing C), the thermistor 43 detects an extremely low temperature. In this case, the CPU 37 detects that the detected temperature of the thermistor 43 is lower than the detected temperature of the corresponding thermistor 43 when the transfer material P is set at an appropriate position. Judge that it is appropriate. This determination can also be made instantaneously with one sheet passing. Further, since the thermistor 44 can detect a temperature higher than a desired value, the CPU 37 can determine that the transport position is inappropriate when several sheets are passed. In other words, the CPU 37 determines that the conveyance position is inappropriate based on the fact that the detected temperature of the thermistor 44 is higher than the detected temperature of the corresponding thermistor 44 when the transfer material P of the same size is set at an appropriate position. to decide. Since the thermistor 41 does not change as much as the detected temperature in the normal sheet passing state, it is difficult for the CPU 37 to determine a state where the transport position is inappropriate. At this time, the CPU 37 warns the user that the conveyance position is inappropriate, but the CPU 37 feeds the transfer material P to the nip portion N so that the temperature of the thermistor 44 becomes 200 ° C. Control to adjust. That is, by increasing the throughput, it is possible to prevent a fixing failure of the unfixed toner image and a fixing device failure and complete the job.

  Also, as shown in FIG. 8, when the transfer material P is a large size having a longitudinal width extending over the positions of the thermistors 41 to 43 (denoted as NG paper passing D), the thermistors 41 to 43 are located in the paper passing area. The position of the thermistor 44 is a non-sheet passing area. In this case, the CPU 37 determines that the detected temperature of the thermistors 41 and 44 is lower than the detected temperature of the corresponding thermistors 41 and 44 when the transfer material P having the same size is set at an appropriate position. That is, it is determined that the conveyance position is inappropriate. This determination can be made based on the number of sheets passed. At this time, the CPU 37 warns the user that the transport position is inappropriate, but the CPU 37 feeds the transfer material P to the nip N so that the temperature of the thermo switch 45 does not operate, that is, the thermistor 44 becomes 200 ° C. Control to adjust the interval. That is, by increasing the throughput, it is possible to prevent a fixing failure of the unfixed toner image and a fixing device failure and complete the job.

As described above, by adopting the configuration as in this reference example , in the case of NG paper A, the temperature is controlled by the detected temperature of the thermistor 42, and in the case of NG paper B, the temperature is detected by the thermistor 43. It can be determined that the position is inappropriate. Further, in the case of NG paper C, the conveyance position can be determined to be inappropriate based on the detection temperature of the thermistor 43 or 44, and in the case of NG paper D, the detection temperature of the thermistors 41 and 44.

  Here, also in the conventional fixing device, the paper is passed at an inappropriate position as described above.

9 to 12 are explanatory views of the arrangement of the thermistor and the thermo switch in the heater of the conventional fixing device. The thermistor and thermoswitch at the same position as in this reference example are assigned the same reference numerals.

  Conventionally, the temperature control thermistor 42 and the thermo switch 45 are always installed at a position that enters the sheet passing area. Further, in a high-speed image forming apparatus or an image forming apparatus capable of printing large-size paper such as A3 as a transfer material, in order to detect a temperature increase in a non-sheet passing portion, the heater 34 is located near the end of the heat generating area 46. A thermistor 44 may be installed.

  Typical thermistors and thermoswitch arrangements are as follows.

FIG. 9 shows a configuration having one temperature control thermistor 42 and a thermo switch 45. FIG. 10 shows a structure having a thermistor 44 in the vicinity of the longitudinal end of the left hand with respect to the sheet passing direction in FIG . FIG. 11 shows a structure having a thermistor 41 in the vicinity of the longitudinal end of the right hand with respect to the paper passing direction in FIG. FIG. 12 shows a configuration in which the thermistors 41 and 44 are further provided in the vicinity of both ends of FIG.

  For each of the above-described configurations, paper was passed at the above-mentioned four inappropriate positions, and the following results were obtained. “OK” indicates a case where inappropriate paper passing is detected (determined that the transport position is inappropriate) with several sheets being passed, and “NG” indicates that inappropriate paper passing cannot be detected or fixing. Means failure or replacement of the device, or damage to the fixing device.

As shown in Table 1, in the case of NG paper passing A, any conventional configuration has the thermistor 42 for temperature control, so that inappropriate paper passing can be detected instantaneously. In the case of NG paper passing B, any conventional configuration does not have a thermistor at the position of the thermistor 43 of this reference example , and therefore improper paper passing cannot be detected, and the elastic layer 33 of the pressure roller 30 cannot be detected. Deterioration will occur. In the case of NG paper C, the configuration shown in FIGS. 10 and 12 having thermistors such as the thermistors 44 and 41 of this reference example can detect inappropriate paper passing, but it takes time to detect. . 9 and 11 that do not have both thermistors 43 and 44, it is difficult to detect inappropriate paper feeding regardless of the number of papers to be passed. In the worst case, the thermo switch 45 malfunctions. . In the case of the NG paper D, inappropriate paper cannot be detected unless both the thermistors 41 and 44 are provided. Conventionally, inappropriate paper can be detected only in the configuration shown in FIG. In other configurations, since it is difficult to detect, the fixing layer may be damaged due to deterioration of the elastic layer of the pressure roller 30.

  If the paper is improperly passed with the conventional configuration shown in FIGS. 9 to 12, not only the elastic layer of the pressure roller 30 is deteriorated but also the thermo switch 45 malfunctions, and there is a possibility that the fixing device is replaced.

With the configuration of this reference example , it can be determined that the transport position is inappropriate regardless of the sheet passing area of the transfer material P, and the job can be completed promptly.

As described above, according to the image forming apparatus of this reference example , it is possible to determine that the conveyance position is inappropriate with the minimum number of sheets to be passed, fixing failure of an unfixed toner image, non-sheet passing portion temperature rise, Further, it is possible to prevent the fixing device from being broken due to a malfunction of the thermo switch.

  Furthermore, by making the thermistors at both ends of the heater heat generation area correspond to different transfer material sizes, it is possible to accurately grasp the temperature rise at the non-sheet passing portion of more transfer material sizes, and to increase the transfer material size to the maximum throughput. The effect is that it can be controlled automatically.

The determination that the conveyance position is inappropriate as in this reference example can be similarly applied to other transfer material sizes.
[Example]

In this embodiment, another example of the image forming apparatus will be described.

In this embodiment, the same reference numerals are given to members / portions common to the fixing device of the reference example , and the description thereof is omitted.

  FIG. 13 shows the thermistors 41 to 44 and the thermo switch 45 on the heater in the fixing device according to this embodiment, the transfer material P conveyed from an appropriate position by the multi-tray 23, and the transfer material passing through the nip portion N. It is explanatory drawing of the temperature distribution when doing.

The multi-tray 23 has restriction plates 40a and 40b as restriction members, and the restriction plates 40a and 40b are connected to automatic fine adjustment shafts (drive sources) 52a and 52b as fine adjustment means. The automatic fine adjustment shafts 52a and 52b are each driven to rotate by a rotational drive system. For example, by rotating the automatic fine adjustment shaft 52a in the direction of the arrow, the automatic fine adjustment shaft moves in the direction of the thick black arrow, and the regulation plate 40a can be driven in the longitudinal direction. 52b can be driven in the same manner . Also, a thermistor (second temperature sensing means) 50, 51 for each sheet passing reference, are placed in the position of -140mm and + 140 mm in the longitudinal symmetrical. The temperature distribution when the transfer material P is passed is as shown in the lower diagram of FIG. When the transfer material P is set at an appropriate position and passed, the thermistors 50 and 51 detect substantially the same temperature as shown in FIG.

In the image forming apparatus of the present embodiment, if the transfer material P is not set at an appropriate position in the multi-tray 23, the CPU 37 has an inappropriate conveyance position based on the detection temperature of the thermistors 50 and 51. Judge. Then, the regulating plate 40 is driven by the automatic fine tuning shafts 52a and 52b.

  Specifically, as shown in FIG. 14, when the transfer material P is fed to the right with respect to the sheet passing direction, the temperature distribution when the transfer material passes through the nip portion N is a temperature profile as shown in the following diagram. It becomes. That is, the detected temperature of the thermistor 50 becomes higher and the detected temperature of the thermistor 51 becomes lower than in the proper position shown in FIG. In such a case, the CPU 37 determines that the transport position is inappropriate, and rotates the automatic fine adjustment shafts 52a and 52b in a predetermined direction by the rotational drive system to move the regulating plates 40b and 40a forward together, thereby transferring the transfer material. Control for correcting the transport position of P to an appropriate position shown in FIG. When the thermistors 50 and 51 have the same temperature, it is determined that the transport position is an appropriate position, and the paper feeding is continued.

In the image forming apparatus according to the present exemplary embodiment, when the conveyance position is inappropriate, the conveyance position of the transfer material P can be corrected to an appropriate position using the automatic fine adjustment axis. Thereby, without trouble of the user, fixing failure of the unfixed toner image, non-sheet passing portion temperature rise, fixing device failure due to malfunction of the thermo switch, etc. can be prevented, and misprint display is not performed as much as possible. The transfer material can be automatically set at an appropriate position, and the job can be completed .

[Others]
1) The fixing device is not limited to the film heating type fixing device of the embodiment, and can be applied to, for example, a heat roller type fixing device, an electromagnetic induction heating type fixing device, or the like.

When the fixing device is applied to a heat roller type fixing device, a fixing roller heated by heating means such as a halogen heater can be used as the heating rotator. Four thermistors as temperature detecting means can be arranged in proximity to or in contact with the outer peripheral surface of the fixing roller.

When the fixing device is applied to an electromagnetic induction heating type fixing device, a coil unit having an exciting coil and a magnetic core can be used as the heating means. As the heating rotator, an electromagnetic induction exothermic flexible film that generates heat by the magnetic flux generated by the coil unit can be used. Four thermistors as temperature detecting means can be arranged in proximity to or in contact with the outer peripheral surface of the flexible film.

  2) The image forming method of the unfixed toner image on the transfer material is not limited to the transfer type electrophotographic method, but may be a direct type electrophotographic method, a transfer type or direct type electrostatic recording method, and a magnetic method. The recording method is arbitrary.

Configuration model diagram of an example of an image forming apparatus Cross-sectional side view of an example of a fixing device according to a reference example An explanatory diagram of a thermistor and a thermo switch on a heater in a fixing device according to a reference example , a transfer material conveyed from an appropriate position by a multi-tray, and a temperature distribution when the transfer material passes through the nip portion. Explanatory diagram (1) of a transfer material that is not set at an appropriate position by the multi-tray and a temperature distribution when the transfer material passes through the nip portion Explanatory diagram (2) of the transfer material that is not set at the proper position by the multi-tray and the temperature distribution when the transfer material passes through the nip Explanatory diagram of the transfer material that is not set at the proper position by the multi-tray and the temperature distribution when the transfer material passes through the nip (3) Explanatory diagram (4) of a transfer material that is not set at an appropriate position by the multi-tray and a temperature distribution when the transfer material passes through the nip portion. Explanatory drawing (5) of a transfer material that is not set at an appropriate position by the multi-tray and a temperature distribution when the transfer material passes through the nip portion Explanatory drawing (1) of arrangement | positioning form of the thermistor and thermoswitch in the heater of the conventional fixing device Explanatory drawing (2) of arrangement | positioning form of the thermistor and thermoswitch in the heater of the conventional fixing device Explanatory drawing (3) of the arrangement | positioning form of the thermistor and the thermo switch in the heater of the conventional fixing device Explanatory drawing (4) of arrangement | positioning form of the thermistor and thermoswitch in the heater of the conventional fixing device Thermistor and thermo switch on the heater in the fixing device according to the embodiment , the transfer material conveyed from an appropriate position by the multi-tray, and the temperature distribution diagram when the transfer material passes through the nip portion Illustration of the transfer material that is not set at the proper position by the multi-tray and the temperature distribution when the transfer material passes through the nip

27 ... Fixing film, 34 ... Ceramic heater, 30 ... Pressure roller,
41, 42, 43, 44 ... thermistor, 37 ... DC controller

Claims (2)

An image forming apparatus set to convey a recording material in accordance with a conveyance reference at the center in the width direction,
An image forming unit for forming an image on a recording material;
A paper feeding unit having a movable regulating plate that regulates an end portion in the width direction of the recording material, and a recording material to be conveyed to the image forming unit;
A heating rotary member, a heating means for heating the heating rotating body, anda pressure rotating body to form a nip portion in contact with the heating rotating body, a recording medium one sandwiched and conveyed matter in the nip Fixing means for heating and fixing the image formed on the recording material to the recording material;
In an image forming apparatus having
First temperature detection means for detecting the temperature at or near the conveyance reference, and at least one second temperature detection for detecting the temperature at or near the longitudinal end of either the heating rotator and the heating means. And the temperature of the heating rotating body and any one of the heating means outside the conveyance area of the minimum size of the recording material conveyed by the conveyance reference and closer to the conveyance reference by the second temperature detection means. Any one of the first temperature detecting means, the second temperature detecting means, and the third temperature detecting means has a third temperature detecting means for detecting and a drive source for driving the regulating plate . When it is determined that the transport position of the recording material is inappropriate based on the detected value, the drive source so that the center in the width direction of the recording material placed on the paper feeding unit matches the transport reference Move the restriction plate by An image forming apparatus characterized in that. The heating rotator is a film, the heating means is in contact with the inner surface of the film, and the nip portion is formed by the heating means and the pressure rotator via the film. The image forming apparatus according to claim 1.