JP7114372B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as an electrophotographic copier and an electrophotographic printer.

An image forming apparatus such as an electrophotographic copier or an electrophotographic printer includes an image forming unit that forms an unfixed toner image on a recording material, a fixing unit that fixes the toner image formed on the recording material to the recording material, have. The fixing unit includes a fixing member such as a cylindrical film or roller, a heating member that heats the fixing member by generating heat when supplied with electric power, and a nip portion forming member that forms a nip portion together with the fixing member. have. In the fixing section, the recording material on which the unfixed toner image is formed is nipped and conveyed while being heated, whereby the toner image is fixed on the recording material.

In the image forming apparatus described above, when the user selects the type of recording material to be used, the printing operation is performed according to the manufacturer's recommended print settings related to the heat fixing process of the fixing unit (hereinafter referred to as the manufacturer's recommended print settings). is doing. This makes it possible to obtain optimum image quality according to the type of recording material.

In the image forming apparatus described above, it is necessary to select print settings recommended by the manufacturer in order to obtain optimum image quality according to the type of recording material. The print settings recommended by the manufacturer achieve image quality that satisfies most users, and differ from the image quality required by individual users. Therefore, in order to achieve the image quality desired by the user, the user himself/herself inputs the print settings according to the type of recording material from the panel operation section provided on the main body of the apparatus (hereafter referred to as user-set print settings). is being done.

Japanese Patent Application Laid-Open No. 2002-200000 describes an invention that performs a printing operation according to the print settings recommended by the manufacturer when the print settings set by the user for the type of recording material determined by a sensor are different from the print settings recommended by the manufacturer. disclosed. According to the invention disclosed in Japanese Patent Application Laid-Open No. 2002-200010, even if the user inputs the print settings by mistake, the image quality recommended by the manufacturer can be obtained.

Japanese Patent Application Laid-Open No. 2002-200002 discloses an invention in which, when the user indicates the type of recording material, the print settings set by the user are prioritized over the print settings recommended by the manufacturer. According to the invention of Patent Document 2, even if the image quality desired by the user and the image quality recommended by the manufacturer are different, the user can obtain the image quality desired by the user.

JP 2012-181223 A JP 2009-251597 A

In the above image forming apparatus, if the small size recording material (narrow paper) is continuously printed at the same print interval as the large size recording material (wide paper), the non-passing area where the small size recording material does not pass through the nip portion of the fixing unit. is known to overheat. If the temperature of the non-passing region of the nip portion rises excessively, the fixing member and the nip portion forming member of the fixing portion may be damaged, resulting in defective images.

When the image quality desired by individual users is different from the image quality satisfied by many users, prioritizing the print settings recommended by the manufacturer based on the type of recording material as in Japanese Patent Application Laid-Open No. 2003-130010 does not sufficiently achieve the image quality desired by the user. Sometimes.

On the other hand, if priority is given to the print settings set by the user as in Japanese Patent Application Laid-Open No. 2002-200020, the print settings set by the user will greatly deviate from the range of the print settings recommended by the manufacturer if the user incorrectly specifies the size of the recording material. There is a possibility that In this case, an image defect may occur due to damage to the fixing section due to excessive temperature rise in the non-passing area of the nip section.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of giving priority to a print mode specified by a user and suppressing the occurrence of defective images due to damage to a fixing section.

In order to achieve the above object, an image forming apparatus according to an aspect of the present invention includes:
an image forming unit that performs an image forming operation for forming an unfixed image on a recording material;
a fixing member, a heating member that heats the fixing member by generating heat when electric power is supplied, and a nip portion forming member that forms a nip portion together with the fixing member, wherein an unfixed image is formed at the nip portion. a fixing unit for fixing an unfixed image on the recording material by heating while nipping and conveying the recording material on which is formed;
In an image forming apparatus having
a printing mode specifying means configured to be operated by a user ;
width information acquiring means for acquiring width information of the recording material in a direction orthogonal to the recording material conveying direction;
a conveying speed information acquisition unit for acquiring conveying speed information of the recording material based on the print mode specified by the user with the print mode specifying unit;
a supply power detection means for detecting power supplied to the heating member;
supply power limit value determining means for determining a limit value of power to be supplied to the heating member based on the conveying speed information acquired by the conveying speed information acquiring means and the width information acquired by the width information acquiring means;
image formation continuation determination means for determining whether or not to continue the image forming operation based on the power detected by the power supply detection means and the power limit value determined by the power supply limit value determination means;
image forming condition switching means for switching an image forming condition of the image forming operation when the image forming continuation determining means determines that the image forming operation cannot be continued;
has
when the power detected by the power supply detection means is within the range of the limit value, the image formation continuation determination means determines that the image formation operation can be continued;
When the power detected by the power supply detecting means is larger than the limit value, the image forming continuation determining means determines that the image forming operation cannot be continued, and the image forming condition switching means increases the conveying speed of the recording material. The image forming operation is continued after switching to the slow speed .

Further, an image forming apparatus according to another aspect of the present invention includes:
an image forming unit that performs an image forming operation for forming an unfixed image on a recording material;
a fixing member, a heating member that heats the fixing member by generating heat when electric power is supplied, and a nip portion forming member that forms a nip portion together with the fixing member, wherein an unfixed image is formed at the nip portion. a fixing unit for fixing an unfixed image on the recording material by heating while nipping and conveying the recording material on which is formed;
In an image forming apparatus having
a printing mode specifying means configured to be operated by a user ;
width information acquiring means for acquiring width information of the recording material in a direction orthogonal to the recording material conveying direction;
a conveying speed information acquisition unit for acquiring conveying speed information of the recording material based on the print mode specified by the user with the print mode specifying unit;
a supply power detection means for detecting power supplied to the heating member;
recording material discriminating means for discriminating the type of recording material;
supply power limit value determining means for determining a limit value of power to be supplied to the heating member based on the conveying speed information acquired by the conveying speed information acquiring means and the width information acquired by the width information acquiring means;
An image for determining whether to continue the image forming operation based on the print mode specified by the user by the print mode specifying means and the print mode determined based on the determination result of the recording material determined by the recording material determination means. formation continuation determination means;
image forming condition switching means for switching an image forming condition of the image forming operation when the image forming continuation determining means determines that the image forming operation cannot be continued;
a temperature detecting means for detecting the temperature of the fixing member;
target temperature determination means for determining a target temperature of the heating member based on the print mode designated by the user with the print mode designation means;
target temperature determination means for determining whether the temperature detected by the temperature detection means follows the target temperature determined by the target temperature determination means;
has
The image formation continuation determination means includes:
When the target temperature attainment determination means determines that the temperature detected by the temperature detection means does not follow the target temperature, the print mode designated by the user by the print mode designation means and the recording material determination means are determined. determining whether or not to continue the image forming operation in the print mode designated by the user by the print mode designating means, based on the selected print mode;
When the target temperature attainment determination means determines that the temperature detected by the temperature detection means follows the target temperature, the power detected by the supply power detection means and the power supply limit value determination means determine whether or not to continue the image forming operation in the print mode specified by the user by the print mode specifying means .

According to the present invention, it is possible to provide an image forming apparatus that can give priority to the print mode specified by the user and can suppress the occurrence of image defects due to damage to the fixing section.

1 is a sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment; FIG. FIG. 2 is a cross-sectional view showing a schematic configuration of a fixing device; A view of the fixing device when viewed from the upstream side in the recording material conveying direction Diagram showing the schematic configuration of the heater A diagram showing the system configuration of an image forming apparatus A diagram showing a circuit configuration related to the fixing control section Image of temperature distribution when the non-passing area rises excessively due to the heat fixing process of wide and narrow paper Image of temperature distribution when the non-passing area is overheated due to heat fixing processing of narrow paper of thick paper and plain paper Image of temperature distribution when the temperature in the non-passing area is excessive due to heat-fixing processing of narrow thick paper at the first speed and the second speed Flowchart of image forming operation FIG. 2 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to a second embodiment; A diagram showing the system configuration of an image forming apparatus The figure which shows the schematic structure of a surface-surface detection part. Flowchart of image forming operation

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although the preferred embodiment of the present invention is the best embodiment of the present invention, the present invention is not limited to the following embodiments, and can be replaced with various configurations within the scope of the idea of the present invention. It is possible.

[Example 1]
<Image forming apparatus 400>
An image forming apparatus 400 according to the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of an example of an image forming apparatus (full-color printer in this embodiment) 400 using electrophotographic recording technology.

The image forming apparatus 400 has an image forming section 10 and a fixing device (fixing section) 30 .

An image forming section 10 that forms an image on a recording material using toner has four image forming stations SY, SM, SC, and SK for yellow, magenta, cyan, and black. Each image forming station has a photosensitive drum (image carrier) 1, a charging member 2, a laser scanner 3, a developing device 4, a transfer member 5, and a cleaner 6 for cleaning the outer peripheral surface of the photosensitive drum. is doing. The image forming unit 10 further includes a belt 7 that carries and conveys the toner image transferred from each photosensitive drum 1 by the transfer member 5, and a secondary transfer member 8 that transfers the toner image onto the recording material P from the belt. is doing.

Since the image forming operation of the image forming unit 10 on the recording material is well known, detailed description thereof will be omitted.

A recording material P such as narrow paper, wide paper, thick paper, or plain paper is stored in a cassette (storage unit) 21 provided in the apparatus main body 400A, and the size of the recording material is detected by a size sensor 60 provided in the cassette. be done. The recording material P stored in the cassette 21 is supplied to the roller 24 one by one through the roller 23 by the rotation of the roller 22 . Then, the recording material P is conveyed to a transfer portion T between the belt 7 and the secondary transfer member 8 by the rotation of the roller 24, and an unfixed toner image (unfixed image) is transferred onto the recording material at the transfer portion. .

The recording material P on which the unfixed toner image is formed is sent to a fixing device (fixing section) 30, and the toner image is heat-fixed onto the recording material by the fixing device. The recording material P coming out of the fixing device 30 is discharged to the tray 26 by the rotation of the roller 25 .

<Fixer (fixing unit) 30>
The fixing device 30 will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is a sectional view showing a schematic configuration of the fixing device 30. As shown in FIG. FIG. 3 is a diagram of the fixing device 30 viewed from the upstream side in the recording material conveying direction X. FIG. This fixing device 30 is a film heating type fixing device.

The fixing device 30 includes a ceramic heater (heating member) 100, a holder (supporting member) 101, a cylindrical film (fixing member) 102, a pressure roller (nip forming member) 103, and a stay (reinforcing member). 105 and .

The heat-resistant and flexible film 102 has a layer thickness of 80 μm to allow quick start. This film 102 has a base layer and a release layer provided on the outer peripheral surface of the base layer. Heat-resistant resins such as polyimide and polyamide-imide can be used as the material of the base layer. As a material for the release layer, a heat-resistant resin having a good releasing property such as a fluororesin such as PTFE or PFA or a silicone resin can be mixed, or the outer peripheral surface of the base layer can be coated with the material alone.

A holder 101 inserted through the hollow portion of the film 102 is a member that supports the heater 100 . The holder 101 also serves to guide the rotation of the film 102 . This holder 101 is made of heat-resistant resin such as liquid crystal polymer or phenol resin. The flat surface of the holder 101 on the roller 103 side is provided with a groove 101a along the direction Y orthogonal to the recording material conveying direction X, and the heater 100 is supported by this groove.

The heater 100 will be described with reference to FIG. The upper part of FIG. 4 shows a schematic configuration of the heater 100 on the roller 103 side, and the lower part shows a schematic configuration of the heater on the side opposite to the roller side.

The heater 100 has an elongated ceramic substrate 100a made of alumina, aluminum nitride, or the like. On the flat surface of the substrate 100a opposite to the roller 103 side, first and second resistance heating elements 100b1 and 100b2 that generate heat when energized are provided on one end side and the other end side of the substrate in the recording material conveying direction X. is provided along the longitudinal direction of the In the direction Y perpendicular to the recording material conveying direction X, the heating elements 100b1 and 100b2 made of Ag/Pd (silver palladium) or Ta ₂ N have the same heat generation distribution per unit area.

The flat surface further includes an electrode 100c1 for supplying power to the heating element 100b1, an electrode 100c2 for supplying power to the heating element 100b2, a common electrode 100c3 for supplying power to each heating element, and a protection electrode for each heating element. and a protective layer 100d for ensuring insulation. In this embodiment, the protective layer 100d is a glass layer.

On the other hand, the flat surface of the substrate 100a on the roller 103 side is provided with a sliding layer (glass layer in this embodiment) 100e for reducing the frictional force with the inner peripheral surface (inner surface) of the film 102. FIG.

In the direction Y orthogonal to the recording material conveying direction X, on the surface of the protective layer 100d of the heater 100, a thermistor (temperature detection means) for detecting temperature rise in the non-passing area of the film 102 is provided at both ends of the large-size recording material passing area. 81a and 81b are brought into contact. The surface of each thermistor 81a, 81b opposite to the protective layer 100d side is brought into contact with the heat-sensitive surface of the temperature protection element 104 (see FIG. 2). Each thermistor 81a, 81b is 152 mm away from the conveying center of the recording material P, and is positioned to be a non-passing area during A4 horizontal feeding (A4 horizontal width 297 mm) or LRTTER horizontal feeding (LRTTER horizontal width 279 mm).

In this embodiment, the width of the large-size recording material passage area is 320 mm, and the thermistors 81a and 81b are arranged at positions where high productivity can be maintained for A4 transverse feeding, but the arrangement positions of the thermistors are not limited to this embodiment.

A thermistor (temperature detection means) 80 for temperature control is brought into contact with the small-size recording material passage area on the inner surface of the film 102 in the direction Y orthogonal to the recording material conveying direction X. As shown in FIG. This thermistor 80 is supported by a holder 101 (see FIG. 2). The thermistor 80 is 20 mm away from the conveying center of the recording material P, and is located at a position that serves as a passage area during conveying of the small-sized recording material.

The roller 103 has a metallic core 103a, a roller portion (elastic layer) 103b provided on the outer peripheral surface of the cored bar, and a release layer 103c provided on the outer peripheral surface of the roller portion. there is The roller portion 103b is formed by foaming heat-resistant rubber such as silicone rubber or fluororubber, or silicone rubber. The release layer 103c is made of fluororesin such as PTFE and PFA. Both ends of the cored bar 103a are rotatably supported by a frame 108 of the fixing device 30 via bearings 107 (see FIG. 3) in a direction Y orthogonal to the recording material conveying direction X. As shown in FIG.

A stay 105 inserted through the hollow portion of the film 102 is installed on the surface of the holder 101 opposite to the roller 103 side. Both ends of the stay 105 are supported by a frame 108 in a direction Y orthogonal to the recording material conveying direction X. As shown in FIG. The stay 105 serves to reinforce the holder 101 .

As shown in FIG. 3, both ends of the stay 105 are pressed in the thickness direction Z of the recording material by pressure springs 109 . The stay 105 presses the holder 101 against the inner surface of the film 102 by the pressing force of the spring 109, thereby crushing the roller portion 103b of the roller 103 and elastically deforming the outer peripheral surface (surface) of the roller portion and the outer peripheral surface (surface) of the film 102. A nip portion N having a predetermined width is formed in the recording material conveying direction X.

<Heating and fixing process operation>
The heat fixing operation of the fixing device 30 will be described with reference to FIGS. 2, 3 and 4. FIG.

The driving force of the motor M (see FIG. 3) is transmitted to the metal core 103a of the roller 103 through the gear G, thereby rotating the roller in the direction of the arrow shown in FIG. The film 102 rotates in the direction of the arrow shown in FIG.

When electric power is supplied to the electrodes 100c1, 100c2 and 100c3 from the AC power supply 50 to the heating elements 100b1 and 100b2 of the heater 100 through the connectors C1 and C2, the heating elements 100b1 and 100b2 generate heat and the temperature of the heater rises rapidly. . The fixing control unit 415 controls the timing of energization of the fixing driving circuit 309 so that the temperature of the inner surface of the film 102 detected by the thermistor 80 is maintained at a predetermined target temperature (fixing temperature).

The recording material P on which the unfixed toner image t is formed is heated while being nipped and conveyed by the nip portion N, whereby the toner image is fixed on the recording material.

<System Configuration of Image Forming Apparatus 400>
FIG. 5 is a block diagram showing the system configuration of the image forming apparatus 400. As shown in FIG.

The image forming apparatus 400 has a video controller 402 including a CPU and memories such as ROM and RAM, and a printer engine 403 . A host computer 401 is connected to a video controller 402 in the image forming apparatus 400 via a network, parallel interface, serial interface, or the like. The video controller 402 rasterizes print data transmitted when a print start instruction is received from the host computer 401 into image data, and transmits the rasterized image data to the printer engine 403 .

Video controller 402 will be described. The video controller main control unit 404 has a panel operation unit (print mode specifying means) 406 that determines the print mode based on instructions from the user. The video controller 402 notifies the print mode to the printer engine 403 via the communication interface.

The printer engine 403 will be explained. The printer engine main control unit 405 has a video I/F control unit 407 , a sensor control unit 414 , a fixing control unit 415 and an image formation control unit 408 .

The video I/F control unit 407 receives the print mode, recording material supply/discharge timing, recording material size, and print start instruction from the video controller 402, and notifies the image formation control unit 408 of the instruction from the video controller. do.

The sensor control unit 414 notifies the size information of the recording material P input from the size sensor 60 to the video controller 402 via the video I/F control unit 407 .

The fixing control unit 415 includes a power supply detection unit (supply power detection unit) 416, a power supply unit (power supply unit) 417, a temperature detection unit (temperature detection unit) 418, and a target temperature determination unit (target temperature determination unit). ) 419 and .

The supplied power detection unit 416 detects the voltage and current between the AC power supply 50 and the heater 100 using the AC voltage detection circuit 307 and the AC current detection circuit 308 (see FIG. 6), and detects the voltage value and current supplied to the heater. Based on the value, the power supplied to the heater is calculated in real time. In this embodiment, the power supplied to the heater is calculated using both the voltage between the fixing section 30 and the AC power supply 50 and the current flowing through the fixing section. may be used to calculate the power supplied to the heater.

The power supply unit 417 controls the ON/OFF timing of the triac 71 in synchronization with the zero-cross signal input from the zero-cross generation circuit 306 to the fixing control unit 415 .

A temperature detection unit 418 detects the temperature of the small-size recording material passage area on the inner surface of the film 102 using the thermistor 80 . The temperature detection unit 418 further detects the temperature of the small-size recording material non-passing area of the film 102 using thermistors 81a and 81b.

The target temperature determination unit 419 determines the target temperature of the heater 100 based on the print mode designated (set) by the user through the panel operation unit 406 .

The image forming control unit 408 includes a width information acquisition unit (width information acquisition means) 409 , a conveyance speed information acquisition unit (conveyance speed information acquisition means) 410 , and a supply power limit value determination unit (supply power limit value determination means) 411 . and have The image formation control section 408 further has an image formation continuation determination section (image formation continuation determination means) 412 and an image formation condition switching section (image formation condition switching means) 413 .

The width information acquisition unit 409 acquires width information of the recording material from the size information of the recording material based on the status information input from the size sensor 60 when the recording material P is set in the cassette 21 . The width information is information about the dimension of the recording material P in the direction Y perpendicular to the recording material conveying direction X. FIG.

A conveying speed information obtaining unit 410 obtains conveying speed information of the recording material P from a print mode-conveying speed conversion table (not shown) based on the print mode specified from the panel operation unit 406 .

The supply power limit value determination unit 411 determines the supply power limit value based on the width information acquired from the width information acquisition unit 409 and the conveying speed information acquired from the conveying speed information acquisition unit 410 .

The image forming continuation determination unit 412 determines whether to continue the image forming operation based on the supply power detected by the supply power detection unit 416 and the supply power limit value determined by the supply power limit value determination unit 411. .

An image forming condition switching unit 413 switches image forming conditions such as a conveying speed, suspends image forming, and the like.

<Circuit Configuration Related to Fixing Control Unit 415>
A circuit configuration related to the fixing control unit 415 will be described with reference to FIG. FIG. 6 shows a fixing controller 415, a fixing device 30, an AC power supply 50, a switching power supply (hereinafter referred to as a power supply) 64, a zero cross generation circuit 306, an AC voltage detection circuit 307, and an AC current detection circuit 308. , and a fixing drive circuit 309. FIG.

AC power supply 50 is connected to power supply 64 and heater 100 via AC filter 51 . The AC power supply 50 is further connected to the zero cross generation circuit 306 via the AC filter 51 .

The zero cross generation circuit 306 is configured such that the output signal is inverted when the voltage of the AC power supply 50 is below or above a threshold voltage in the vicinity of 0 V, and is used for heater drive timing control.

The heater 100 is driven on the basis of the zero cross timing by a fixing drive circuit 309 constructed using a triac 71 and a triac coupler 72 or the like. The heater 100 generates heat when supplied with power, the temperature of the film 102 upstream of the nip portion N in the recording material conveying direction X is detected by the thermistor 80, and the heater temperature is detected by thermistors 81a and 81b.

Each thermistor 80 , 81 a , 81 b is configured such that the divided voltage with the fixed resistor 55 is input to the analog input ports AN 0 - 2 (3 types) of the temperature detector 418 . Each thermistor 80, 81a, 81b has a characteristic that the resistance value decreases as the temperature rises, and the divided voltage is monitored by the temperature detection unit 418, based on a preset voltage-temperature conversion table (not shown). Confirm the current temperature.

A power supply unit 417 outputs a Drive signal for driving the fixing drive circuit 309 based on the temperature detected by the temperature detection unit 418 . On the other hand, the power supply 64 includes a diode bridge 61 for rectifying the AC voltage, a smoothing capacitor 62, and a DC-DC converter 63 for generating a DC voltage in the subsequent stage. A DC voltage generated by the power supply 64 is supplied to a secondary side load 65 such as a control section and a drive section of the image forming apparatus 400 .

The supplied power detection unit 416 detects the voltage/current supplied to the heater 100 by the AC voltage detection circuit 307 and the AC current detection circuit 308 .

The AC voltage detection circuit 307 outputs a voltage value corresponding to the effective value voltage of the heater 100 . The supplied power detection unit 416 detects the value of the effective voltage input to the heater 100 by receiving the detected voltage value output from the AC voltage detection circuit 307 at the analog input port AN3.

On the other hand, the AC current detection circuit 308 is arranged at a position where it can detect the value of the current flowing through the heater 100, and the power supply detection unit 416 detects the detected current value output from the AC current detection circuit 308 at the analog input port AN4. is received, the current flowing through the heater 100 is detected.

<Temperature Control Pattern Control of Heater 100>
Temperature control pattern control (hereinafter also referred to as temperature control) of the heater 100 is performed by the power supply unit 417 . The power supply unit 417 controls the turn-on timing of the fixing driving circuit 309 at a ratio (%) (hereinafter referred to as energization duty) obtained by equally dividing the area of the half cycle of the zero-crossing signal output from the zero-crossing generation circuit 306 by 100. . Thus, the power supplied to the heater 100 is controlled in 101 steps from 0% to 100%.

This energization duty is determined from the difference between the target temperature determined by the target temperature determination unit 419 (see FIG. 5) and the detected temperature of the thermistor 80 detected by the temperature detection unit 418 . At the start of power supply to the heater 100, a large power supply duty is set because the difference between the target temperature and the temperature detected by the thermistor 80 is large. As the detected temperature of the thermistor 80 approaches the target temperature, the difference from the target temperature becomes smaller, so the energization duty becomes smaller. The energization duty after the thermistor 80 reaches the target temperature requires electric power for compensating for the amount of heat lost when the unfixed toner image formed on the recording material P is fixed.

<Supply power calculation method>
The supply power detection unit 416 acquires the analog value of the voltage supplied to the heater 100 from the analog input port AN3 and acquires the analog value of the current supplied to the heater from the analog input port AN4 every half cycle of the zero-cross signal. A table (not shown) for converting the acquired analog values into actual current/voltage is used to determine the current value Ifsr/voltage value Vfsr, and the power Pfsr supplied to the heater 100 is calculated by Equation (1).

Pfsr=(Ifsr)×(Vfsr) Equation 1
By calculating the power supplied to the heater 100 from when the leading edge of the recording material enters the nip portion N to when the trailing edge of the recording material exits the nip portion in the recording material conveying direction X, the average power supply for each page is calculated. do.

<Relationship Between Excessive Temperature Rise in Small-Size Recording Material Non-Passing Area and Supply Power>
The relationship between the excessive temperature rise in the small-size recording material non-passing area of the heater 100 and the power supplied to the heater will be described with reference to FIGS. 7A, 7B, and 7C.

FIG. 7A shows the film when the temperature of the non-passing area is excessively high due to the heat fixing process of the wide paper (large size recording material) and the narrow width paper (small size recording material) after the thermistor 80 reaches the target temperature. 102 shows a temperature distribution image in a direction Y orthogonal to the recording material conveying direction X. FIG.

The temperature distribution when the wide paper is heat-fixed is almost symmetrical, and the peak of the excessive temperature rise in the non-passing area of the wide paper is located at almost the same position as the thermistors 81a and 81b. This is because heat is taken away from the wide paper passing area by the wide paper, and heat is taken from the non-wide paper passing area by heat radiation from the end of the roller 103 and the end of the film 102 .

In the temperature distribution when the narrow paper is heat-fixed, the peak of the excessive temperature rise in the non-passing area of the narrow paper is located inside the wide paper, and becomes even higher. This is because the non-passing area of the narrow paper is larger than that of the wide paper, and the influence of heat radiation from the end of the roller 103 and the end of the film 102 is small. That is, in the case of narrow paper, in the direction Y orthogonal to the recording material conveying direction X, the non-passing area excessive temperature peak at positions inside the thermistors 81a and 81b is higher than that of wide paper.

FIG. 7B shows the recording material of the film 102 when the temperature of the non-passing area is excessively high due to heat-fixing of narrow paper (small size recording material) of thick paper and plain paper after the thermistor 80 reaches the target temperature. A temperature distribution image in a direction Y perpendicular to the transport direction X is shown.

The temperature distribution of the narrow paper in FIG. 7(a) becomes the temperature distribution of the plain paper in FIG. 7(b). The temperature distribution when thick paper is heat-fixed has a higher peak than that of plain paper. This is because thick paper absorbs a larger amount of heat during the heat fixing process than plain paper, and thus requires a large amount of electric power to be supplied to maintain the target temperature of the heater 100 .

FIG. 7(c) shows the case where the temperature of the non-passing area becomes excessive due to the thermal fixing processing of the thick narrow paper (small size recording material) at the first speed and the second speed after the thermistor 80 reaches the target temperature. A temperature distribution image of the film 102 in a direction Y orthogonal to the recording material conveying direction X is shown. The first speed was 200 mm/s and the second speed was 100 mm/s.

The temperature distribution of the cardboard shown in FIG. 7B is the temperature distribution at the first speed. The temperature distribution when thick paper is heat-fixed at the second speed has a lower peak than that of plain paper in FIG. 7B. This is because the faster the conveying speed, the smaller the heat conduction coefficient transmitted to the cardboard, and the smaller the amount of heat taken away by the cardboard, so the power supply required to maintain the target temperature is small.

As described above, the non-passing area excessive temperature rise increases as the power supplied to the heater 100 increases. The print mode set by the user may not match the print mode suitable for the recording material P set in the cassette 21 . In this case, the feed speed determined based on the print mode specified by the user does not match the feed speed suitable for the recording material stored in the cassette 21, and the power supplied to the heater 100 may become excessively large. . If the supplied power is increased in this manner, there is a possibility that the non-passing region excessively rises in temperature more than expected.

However, there is a possibility that the designation by the user is not an erroneous designation, but is intended by the user. I want to execute the image forming operation based on the print mode.

In this embodiment, it is determined whether the heat fixing process can be performed without damaging the fixing device 30 based on the power supplied to the heater 100 . Since the degree of excessive temperature rise in the non-passing area varies depending on the width size of the recording material P, the power supply threshold (hereinafter also referred to as the power supply limit value (restriction value)) supplied to the heater 100 varies depending on the width size of the recording material. must have for each width size. The power supply threshold is determined by an experimental study assuming a severe case where excessive temperature rise in the non-passing area occurs due to a combination of environmental temperature in which the image forming apparatus 400 is installed, the warm state of the fixing device 30, and the amount of applied toner. Ideally, the power supply threshold is determined for each width size of the recording material P. FIG.

In this embodiment, the width size of the recording material P that can be specified is divided into a plurality of ranges as shown in Table 1, and the power that can be supplied is limited according to the width size that causes the most severe overheating in the non-passing area for each range. determined the value. The suppliable power limit value is as shown in Table 1.

＜画像形成動作のフローチャート＞
図８に、本実施例の画像形成装置４００について、上記の条件で画像形成動作を実施した場合のフローチャートを示す。

<Flow chart of image forming operation>
FIG. 8 shows a flow chart when the image forming operation is performed under the above conditions for the image forming apparatus 400 of this embodiment.

In S<b>101 , the user selects (sets) a print mode from the panel operation unit 406 . The video controller 402 notifies the printer engine 403 of the print mode specified by the user through the panel operation unit 406 through the video I/F control unit 407 (not shown). The printer engine 403 receives the print mode at the video I/F control unit 407 and notifies the image formation control unit 408 of the print mode.

In S102, the sensor control unit 414 detects the recording material set in the cassette 21 by the user using the size sensor 60, and transmits the width size (width information) of the recording material P to the image formation control unit 408 via the video I/F control unit 407. to notify you.

In S103, when the video controller 402 receives a print start instruction from the host computer 401, the video controller 402 starts image development and notifies the printer engine 403 of an image formation start instruction via a video I/F control unit (not shown). The printer engine 403 receives the print start instruction at the video I/F control unit 407 and notifies the image formation control unit 408 of the image formation start instruction.

In S104, upon receiving the image formation start instruction, the image formation control unit 408 determines the conveying speed from the print mode at that time. Based on Table 1, the suppliable power limit value is determined from the transport speed based on the print mode specified by the user and the width size of the recording material P set in the cassette 21 by the user.

In S105, the image formation control unit 408 starts an image formation preparation operation based on the image formation conditions corresponding to the print mode designated by the user. At the same time as the image forming preparation operation, the fixing control unit 415 is instructed to start temperature adjustment control based on the image forming conditions. The fixing control unit 415 determines the target temperature and the energization duty based on the image forming conditions, and the power supply unit 417 supplies the energization duty toward the target temperature determined based on the temperature detection unit 418 .

In S106, the image forming control unit 408 starts the image forming operation when the image forming start condition is satisfied.

In S107, when the feeding operation of the recording material P by the rotation of the rollers 22 and 23 is started and the leading edge of the recording material reaches the roller 24, the fixing control unit 415 starts temperature control of the nip portion. Then, the fixing control unit 415 executes (starts) temperature adjustment control to determine the energization duty based on the temperature difference between the target temperature determined based on the image forming conditions and the current temperature detected by the thermistor 80 detected by the temperature detection unit 418 . )do.

In S108, the fixing control unit 415 uses the current/voltage detected by the power supply detection unit 416 to determine the amount of time between when the leading edge of the recording material enters the nip portion N of the fixing device 30 and when the trailing edge of the recording material exits the nip portion. is calculated and notified to the image formation control unit 408 .

In S<b>109 , the image formation control unit 408 determines the next operation according to the presence or absence of an image formation start instruction from the video controller 402 . If there is an image formation start instruction (YES), the process proceeds to S110, and if not (NO), the process proceeds to S113.

In S110, the average power supply acquired by the power supply detection unit 416 is compared with the power supply limit value determined by the power supply limit value determination unit 411, and it is determined whether or not the image forming operation can be continued. If the average power supply is smaller than the power limit value that can be supplied, it is determined that the image forming operation can be continued, and the process returns to S106 to continue the image forming operation. It is determined that the operation cannot be continued, and the process proceeds to S111.

In S111, the image forming condition switching unit 413 switches the image forming conditions. In this embodiment, the transport speed is switched to a slower speed.

In S112, the image formation control unit 408 determines whether or not the switching of the image formation conditions has been completed. In S112, it waits until the switching is completed, and when the switching is completed, the process returns to S106 to continue the image forming operation.

In S113, the image forming control unit 408 stops the image forming operation and instructs the fixing control unit 415 to stop the temperature adjustment control.

The image forming apparatus 400 of this embodiment performs the following processing when the print mode specified by the user from the panel operation unit 406 and the width size of the recording material P set in the cassette 21 are different.

That is, when the average power supply for each page calculated by the power supply detection unit 416 exceeds the suppliable power limit value determined by the power supply limit value determination unit 411, the image forming conditions are switched. As a result, the possibility of image defects due to damage to the fixing device 30 due to excessive temperature rise in the non-passing area can be suppressed. When the average power supply does not exceed the limit value of the power that can be supplied, the image forming operation can be continued, and image quality and productivity desired by the user can be provided within a range in which the fixing device 30 is not damaged.

Therefore, it is possible to give priority to the print mode specified by the user, and to suppress the occurrence of image defects due to damage to the fixing section 30 .

The switching of the image forming conditions is not limited to the conveying speed, and the image forming operation is interrupted to perform a cooling operation of cleaning the outer peripheral surface of the rotating photosensitive drum 1 with the cleaner 6, or the image forming operation is interrupted to perform a panel operation. A warning may be notified to the unit 406 .

The switching of the image forming conditions is performed by at least one of the print mode, the target temperature, the image forming interval when images are continuously formed on the recording material, and the image formation stop time when images are continuously formed on the recording material. A single switching operation may be performed.

[Example 2]
Another example of the image forming apparatus 400 will be described. In this embodiment, only the configuration different from that of the first embodiment will be explained.

FIG. 9 is a cross-sectional view showing a schematic configuration of an example of the image forming apparatus 400 according to this embodiment.

The image forming apparatus 400 shown in this embodiment has a medium discriminating device 90 between the roller 24 and the transfer section T. As shown in FIG. The media discrimination device 90 has a surface property detection section (surface property detection means) 40 and a basis weight detection section (basis weight detection means) 33 .

<System Configuration of Image Forming Apparatus 400>
FIG. 10 is a block diagram showing the system configuration of the image forming apparatus 400. As shown in FIG.

A media determination control unit (recording material determination means) 900 is added to the printer engine control unit 405 shown in FIG. The media determination control unit 900 determines the type of recording material from the surface property of the recording material P detected by the surface property detection unit 40 and the basis weight of the recording material P detected by the basis weight detection unit 33 .

A target temperature attainment determination unit (target temperature attainment determination means) 920 is added to the fixing control unit 415 in FIG. The target temperature attainment determination unit 920 determines that the target temperature has been reached (followed) based on whether the temperature detected by the thermistor 80 detected by the temperature detection unit 418 has reached or exceeded the target temperature and continued for a predetermined time or longer. do.

<Surface property detector 40>
The surface property detector 40 will be described with reference to FIGS. 9, 10 and 11. FIG. FIG. 11 is a diagram showing a schematic configuration of the surface texture detection unit 40. As shown in FIG. 11A is a cross section showing a schematic configuration of the surface property detection unit 40, and FIG. 11B is a perspective view of the surface property detection unit viewed from the upstream side in the recording material conveying direction X. FIG.

As shown in FIG. 9, the surface property detection unit 40 is installed so as to face the recording material conveying path in the thickness direction Z of the recording material P. As shown in FIG.

In FIGS. 11A and 11B, reference numeral 41 denotes an LED, which is irradiation means for irradiating light onto the surface of the recording material P, and irradiates the surface of the recording material P with light at an angle of approximately 10 degrees to perform recording. It is arranged to generate light and dark (shadow) according to the surface properties of the material.

An imaging lens 42 forms an image of light reflected from the surface of the recording material P by the light emitted from the LED 41 .

A CMOS line sensor 43 picks up the light imaged by the imaging lens 42, and picks up the brightness (shadow) generated on the surface of the recording material P. FIG.

46a and 46b are reference plates (hereinafter referred to as inner reference plate 46a and inner reference plate 46b) located at the ends of the area where the light of the LED 41 can be irradiated.

A protective member 47 protects the imaging lens 42 and the LED 41 .

The imaging lens 42 and the line sensor 43 are arranged so as to be orthogonal to the recording material conveying direction X. As shown in FIG. As a result, the line sensor 43 can simultaneously capture the reflected light reflected from the surface of the recording material P by the light emitted from the LED 41 and the reflected light reflected from the inner reference plates 46a and 46b by the light emitted from the LED. be.

<Method for Determining Surface Properties of Recording Material P>
The surface property detection unit 40 has an imaging unit 901 and an imaging unit 902, as shown in FIG.

In the imaging unit 901, the LED 41 irradiates the surface of the recording material P being conveyed with light. Reflected light (brightness and darkness) from the recording material P forms a surface image of the recording material through the imaging lens 42 .

The imaging unit 902 captures the formed surface image with the line sensor 43 . A surface image captured by the line sensor 43 is input to the imaging unit 902 . The imaging unit 902 A/D-converts the surface image input from the line sensor 43 pixel by pixel, and simultaneously reads the images on the same straight line in the direction Y orthogonal to the recording material conveying direction X line by line. In this embodiment, an 8-bit A/D conversion IC is used, and the A/D conversion outputs values from 0 to 255. The imaging unit 902 further joins the input surface images in the transport direction to obtain a two-dimensional surface image.

So far, the method of determining the surface properties of the recording material P using the line sensor 43 has been described, but this is a general configuration. For example, the configuration of the line sensor 43 such as the number of LEDs 41 is not limited to the configuration described above.

<Basis Weight Detection Unit 33>
The basis weight detection unit 33 will be described with reference to FIGS. 9 and 10. FIG.

As shown in FIG. 9, in the grammage detection unit 33, in order to acquire the grammage information of the conveyed recording material P, the transmission piezo element 31 and the reception piezo element 32 are arranged so as to sandwich the conveying path for conveying the recording material. are placed. The grammage here is the mass per unit area of the recording material P, and is represented by [g/m ² ].

The basis weight detection unit 33 has an ultrasonic transmission unit (ultrasonic transmission means) 903 and an ultrasonic reception unit (ultrasonic reception means) 904, as shown in FIG.

In the transmission section 903, when a pulse voltage of a predetermined frequency is input to the electrode terminal of the transmission section, the piezoelectric element 31 oscillates and a sound wave is generated and propagates in the air. When the sound wave reaches the recording material P, the sound wave vibrates the recording material. The sound wave generated by the transmitting section 903 in this way propagates through the recording material P to the piezo element 32 . The receiving section 904 causes the electrode terminals of the receiving section to generate an output voltage corresponding to the amplitude of the sound wave received by the piezo element 32 . This is the principle of operation when the piezoelectric elements 31 and 32 are used to transmit and receive ultrasonic waves.

In this embodiment, the transmitter 903 and the receiver 904 transmit and receive ultrasonic waves having frequency characteristics of 32 kHz. The frequency of the ultrasonic wave is set in advance, and a frequency within an appropriate range may be selected according to the configuration of the transmitter 903 and receiver 904, the detection accuracy, and the like.

Upon receiving an instruction to start measuring the basis weight of the recording material P, the basis weight detection unit 33 instructs the transmission unit 903 to transmit an ultrasonic signal. When instructed to transmit an ultrasonic signal, the transmission unit 903 transmits only the direct wave emitted by the piezoelectric element 31 to the piezoelectric element 31 in order to reduce the influence of disturbance such as reflected waves from the recording material P and members around the conveying path. 32 outputs a constant pulse for reception. This is called a burst wave.

The receiving unit 904 receives the ultrasonic waves transmitted from the transmitting unit 903 or the ultrasonic waves transmitted through the recording material P via the piezoelectric element 32 . The receiving unit 904 sequentially performs A/D conversion to convert the received signal from an analog signal to a digital signal, and extracts the peak (maximum value) of the signal. This peak extraction is performed a predetermined number of times at predetermined intervals for each of the state in which there is no recording material P between the transmitting unit 903 and the receiving unit 904 and the state in which the recording material P is present. The basis weight detection unit 33 calculates the transmission coefficient from the ratio of the average value of the predetermined number of times without the recording material P and the average value of the predetermined number of times with the recording material. This transmission coefficient is a value corresponding to the basis weight, and the basis weight is determined based on this value.

In this embodiment, the type of recording material P is determined based on the detection results of the surface property detection unit 40 and basis weight detection unit 33 .

So far, the method for determining the type of the recording material P by the media determination control unit 900 based on the detection results of the surface property detection unit 40 and the basis weight detection unit 33 has been described, but the determination method is limited to the above. not to be A method of detecting the grammage of the recording material P from the temperature difference between the film 102 and the heater 100 during the heat-fixing operation of the fixing device 30, or other recording material determination method can also be used.

<Flow chart of image forming operation>
FIG. 12 shows a flow chart of the image forming apparatus 400 of this embodiment when the image forming operation is performed under the same conditions as in the first embodiment.

S201 to S205 are the same as S101 to S105 in FIG.

In S206, the media determination control unit 900 is instructed to start measurement without recording material in order to measure basis weight measurement reference data during the image forming preparation operation after the start-up temperature control in S205. In the basis weight detection unit 33 , the media determination control unit 900 acquires data by receiving ultrasonic waves transmitted by the transmission unit when there is no recording material P between the transmission unit 903 and the reception unit 904 .

S207 and S208 are the same as S106 and S107 in FIG.

In S<b>209 , the image formation control unit 408 instructs the media discrimination control unit 900 to start measurement of basis weight when the leading edge of the recording material passes through the media discrimination device 90 . This is because it is necessary to detect the grammage while the posture of the recording material is stable until the leading edge of the recording material reaches the secondary transfer member 8 . In the media determination control unit 900, when the recording material P is present between the transmission unit 903 and the reception unit 904 in the basis weight detection unit 33, the reception unit receives the ultrasonic waves transmitted by the transmission unit and acquires data. The grammage detection unit 33 calculates the transmission coefficient from the measurement data without the recording material and the measurement data with the recording material, and determines the grammage based on the data.

In S210, the image formation control unit 408 instructs the media determination control unit 900 to start measuring the surface properties when the leading edge of the recording material leaves the secondary transfer member 8 and the recording material conveying speed becomes stable. In the media determination control unit 900, the surface property detection unit 40 irradiates the recording material P with light from the LED 41, and captures the surface image of the recording material with the line sensor 43 to acquire data. The surface property detection unit 40 determines the surface property of the recording material P based on this imaging data.

In S211, the type discrimination of the recording material is started. The media determination control unit 900 determines the type of the recording material P being conveyed from the basis weight detected by the basis weight detection unit 33 and the surface property detected by the surface property detection unit 40 .

S212 is the same as S108 in FIG.

In S<b>213 , the image formation control unit 408 determines the next operation according to the presence or absence of an image formation start instruction from the video controller 402 . If there is an image formation start instruction (YES), the process proceeds to S214, and if not (NO), the process proceeds to S219.

In S<b>214 , the fixing control unit 415 determines whether or not the temperature detected by the thermistor 80 has reached the target temperature in the target temperature attainment determining unit 906 . If the target temperature has been reached (YES), the process proceeds to S216; if not (NO), the process proceeds to S215.

In S215, it is determined whether or not the print mode specified by the user and the print mode determined based on the determination result of the recording material type obtained from the media determination control unit 900 are different. If not different (NO), proceed to S217; if different (NO), return to S204.

The conditions for determining NO in S215 are as follows. When the target temperature attainment determination unit 420 determines that the target temperature has not been reached, the print mode determined based on the determination result of the recording material type acquired from the media determination control unit 900 is different from the print mode specified by the user. This is the case when it is determined that there is

In S216, the suppliable power limit determined by the supply power limit determination unit 411 and the average supply power obtained by the supply power detection unit 416 are compared to determine whether the image forming operation can be continued. If the average power supply is smaller than the power limit value that can be supplied (YES), it is determined that the image forming operation can be continued, and the process returns to S207 to continue the image forming operation. If NO), it is determined that the image forming operation cannot be continued, and the process proceeds to S217.

The conditions for determining NO in S216 are as follows. When the target temperature attainment determination unit 420 determines that the target temperature has been reached, the supply power detection unit 416 determines that the average power supply is greater than the suppliable power limit value determined by the supply power limit value determination unit 411. is.

In S217, the image forming control unit 408 stops the image forming operation and instructs the fixing control unit 415 to stop the temperature adjustment control.

In S218, the image forming condition switching unit 413 determines whether switching of the image forming conditions is completed. That is, it is determined whether or not the cooling operation (predetermined time until the excessive temperature rise in the non-passing area stops) for cleaning the outer peripheral surface of the rotating photosensitive drum 1 by the cleaner 6 has been completed. If the cleaning operation is completed (YES), the process returns to S204.

S219 is the same as S113 in FIG.

The image forming apparatus 400 of this embodiment determines the type of the recording material P by the media determination control unit 900 even in the mode in which the image forming operation is performed according to the user's designation. If the target temperature attainment determination unit 420 determines that the temperature detected by the thermistor 80 does not follow the target temperature of the heater 100 in a lower state, the image formation continuation determination unit 412 performs the following processing. That is, whether or not the image forming operation can be performed without damaging the fixing unit 30 is determined based on the print mode based on the determination result of the type of the recording material P by the media determination control unit 900 and the print mode specified by the user. to judge.

Further, image formation continuation determination unit 412 performs the following processing when target temperature attainment determination unit 420 determines that the temperature detected by thermistor 80 is following the target temperature of heater 100 . In other words, whether or not the image forming operation can be performed without damaging the fixing unit 30 is determined based on the average power supplied per page and the power limit value that can be supplied based on the width information of the recording material P set by the user. to judge.

By performing such processing, it is possible to provide the image quality and productivity desired by the user within a range in which the fixing device 30 is not damaged.

The image forming apparatus 400 of this embodiment further performs the following processing when the temperature detected by the thermistor 80 is lower than the target temperature even when the print mode is designated by the user. That is, when the print mode specified by the user is different from the print mode based on the result of discriminating the type of recording material P by the media discrimination control unit 900, the image forming conditions are switched by the image forming condition switching unit 413.

By performing such processing, even when the power supply to the fixing device is not stable, the possibility of image defects due to damage to the fixing device due to excessive temperature rise in the non-passing area is suppressed, and the image quality and image quality desired by the user are suppressed. Productivity can be prioritized.

Therefore, the image forming apparatus 400 of this embodiment can also give priority to the print mode specified by the user, and can suppress the occurrence of image defects due to damage to the fixing section.

The switching of the image forming conditions is not limited to the cooling operation, and the image forming operation may be interrupted and a warning may be notified to the panel operation unit 406 . In addition, the switching of the image forming conditions includes the print mode, transport speed, target temperature, image forming interval when images are formed continuously on the recording material, and image formation stop time when images are continuously formed on the recording material. At least one of the switching operations may be performed.

10 image forming unit, 30 fixing unit, 60 size sensor, 100 ceramic heater,
102 cylindrical film, 103 nip portion forming member, 406 panel operation portion,
410 Conveyance speed information acquisition unit 411 Supply power limit value determination unit
412 image formation continuation determination unit; 413 image formation condition switching unit;
416 power supply detection unit, 900 media discrimination control unit,
N: nip portion, P: recording material, t: unfixed toner image

Claims (7)

an image forming unit that performs an image forming operation for forming an unfixed image on a recording material;
a fixing member, a heating member that heats the fixing member by generating heat when electric power is supplied, and a nip portion forming member that forms a nip portion together with the fixing member, wherein an unfixed image is formed at the nip portion. a fixing unit for fixing an unfixed image on the recording material by heating while nipping and conveying the recording material on which is formed;
In an image forming apparatus having
a printing mode specifying means configured to be operated by a user ;
width information acquiring means for acquiring width information of the recording material in a direction orthogonal to the recording material conveying direction;
a conveying speed information acquisition unit for acquiring conveying speed information of the recording material based on the print mode specified by the user with the print mode specifying unit;
a supply power detection means for detecting power supplied to the heating member;
supply power limit value determining means for determining a limit value of power to be supplied to the heating member based on the conveying speed information acquired by the conveying speed information acquiring means and the width information acquired by the width information acquiring means;
image formation continuation determination means for determining whether or not to continue the image forming operation based on the power detected by the power supply detection means and the power limit value determined by the power supply limit value determination means;
image forming condition switching means for switching an image forming condition of the image forming operation when the image forming continuation determining means determines that the image forming operation cannot be continued;
has
when the power detected by the power supply detection means is within the range of the limit value, the image formation continuation determination means determines that the image formation operation can be continued;
When the power detected by the power supply detecting means is larger than the limit value, the image forming continuation determining means determines that the image forming operation cannot be continued, and the image forming condition switching means increases the conveying speed of the recording material. An image forming apparatus, wherein said image forming operation is continued after being switched to a slow speed . an image forming unit that performs an image forming operation for forming an unfixed image on a recording material;
a fixing member, a heating member that heats the fixing member by generating heat when electric power is supplied, and a nip portion forming member that forms a nip portion together with the fixing member, wherein an unfixed image is formed at the nip portion. a fixing unit for fixing an unfixed image on the recording material by heating while nipping and conveying the recording material on which is formed;
In an image forming apparatus having
a printing mode specifying means configured to be operated by a user ;
width information acquiring means for acquiring width information of the recording material in a direction orthogonal to the recording material conveying direction;
a conveying speed information acquisition unit for acquiring conveying speed information of the recording material based on the print mode specified by the user with the print mode specifying unit;
a supply power detection means for detecting power supplied to the heating member;
recording material discriminating means for discriminating the type of recording material;
supply power limit value determining means for determining a limit value of power to be supplied to the heating member based on the conveying speed information acquired by the conveying speed information acquiring means and the width information acquired by the width information acquiring means;
An image for determining whether to continue the image forming operation based on the print mode specified by the user by the print mode specifying means and the print mode determined based on the determination result of the recording material determined by the recording material determination means. formation continuation determination means;
image forming condition switching means for switching an image forming condition of the image forming operation when the image forming continuation determining means determines that the image forming operation cannot be continued;
a temperature detecting means for detecting the temperature of the fixing member;
target temperature determination means for determining a target temperature of the heating member based on the print mode designated by the user with the print mode designation means;
target temperature determination means for determining whether the temperature detected by the temperature detection means follows the target temperature determined by the target temperature determination means;
has
The image formation continuation determination means includes:
When the target temperature attainment determination means determines that the temperature detected by the temperature detection means does not follow the target temperature, the print mode designated by the user by the print mode designation means and the recording material determination means are determined. determining whether or not to continue the image forming operation in the print mode designated by the user by the print mode designating means, based on the selected print mode;
When the target temperature attainment determination means determines that the temperature detected by the temperature detection means follows the target temperature, the power detected by the supply power detection means and the power supply limit value determination means determine and a power limit value, it is determined whether or not to continue the image forming operation in the print mode specified by the user by the print mode specifying means . The target temperature attainment determination means determines that the target temperature is being followed when the temperature detected by the temperature detection means has remained at or above the target temperature determined by the target temperature determination means for a predetermined time or longer. 3. The image forming apparatus according to claim 2 . The width information acquiring means determines the width information based on information based on a size sensor for detecting the size of the recording material or information based on information on the size of the recording material designated by the user. 4. The image forming apparatus according to any one of claims 1 to 3 . 5. The image according to any one of claims 1 to 4 , wherein the conveying speed information acquisition unit determines the conveying speed information based on a print mode specified by a user through the print mode specifying unit. forming device. The supplied power detection means detects the power supplied to the heating member based on the power calculated using either or both of the voltage between the fixing section and the AC power supply and the current flowing through the fixing section. 6. The image forming apparatus according to any one of claims 1 to 5 , wherein the image forming apparatus determines. The image forming condition switching means continuously controls the printing mode, the conveying speed of the recording material, the cleaning operation for cleaning the carrier carrying the unfixed image in the image forming section, the target temperature of the heating member, and the recording material. 3. An image formation interval when images are formed on the recording material continuously, and at least one switching operation of an image formation stop time when images are continuously formed on the recording material is executed. Item 7. The image forming apparatus according to any one of Item 6 .

Images