JP4039124B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine or a printer that forms an image by an electrophotographic method, and more particularly, to an image forming apparatus with improved control of contact and separation of a temperature uniformizing member.
[0002]
[Prior art]
A fixing device referred to as a heating roller type fixing device comprising at least two fixing members, a rotatable heating roller including a heating source, and a pressure roller provided by pressure bonding to the heating roller; A transfer material carrying the transferred toner image is guided to the fixing device, passed between the two rollers, and the toner image is fixed on the transfer material by the heating and pressing action of both rollers. Such image forming apparatuses are known.
[0003]
Further, in the image forming apparatus, the temperature distribution of the fixing member in a direction orthogonal to the transfer material conveyance direction via a temperature equalizing member provided so as to be able to contact with and separate from at least one of the fixing members. In order to average the above, a technique for controlling the temperature uniformizing member to abut and separate is also known.
[0004]
[Problems to be solved by the invention]
The above-described fixing device is extremely useful because it is easy to handle, can be made compact, and has high safety, and is incorporated in many image forming apparatuses and is still used conveniently. .
[0005]
However, in the case where the toner image formed on the image carrier is transferred onto the transfer material and then the transfer material is heated and pressurized with at least two fixing members, the following inconvenience occurs.
[0006]
That is, when the transfer material having a size in the direction orthogonal to the conveying direction of the transfer material used with respect to the roller length of the fixing member must be continuously processed, Even if the fixing process can be satisfactorily performed on the material, the temperature outside the contact area with the transfer material, in other words, the temperature at both ends of the roller length rises excessively. When a large transfer material is processed, there is a disadvantage that gloss unevenness occurs on the transfer material in contact with the temperature boundary.
[0007]
In addition, at the end of the roller that is in a high temperature state, particularly when the roller has a rubber layer, the service life is remarkably shortened.
[0008]
In order to prevent the temperature rise at both ends, if the size of the transfer material in the direction orthogonal to the transfer direction of the transfer material used is a predetermined size or less, the temperature equalizing member is uniformly started to pass the paper. Accordingly, if the operation of contacting the fixing member or moving away from the fixing member at the end of paper passing is used, there is a problem that energy is wasted and thermal efficiency is deteriorated.
[0009]
The present invention has been made in view of the above points. The main object of the present invention is to increase the temperature of the end portion when processing a transfer material having a predetermined size or less with respect to the roller length as a fixing member with a simple configuration. An object of the present invention is to provide a heat-efficient image forming apparatus having a configuration in which the state and the number of print processed sheets are discriminated and the contact and separation of the temperature uniform member is controlled with respect to the fixing member at an appropriate time.
[0010]
[Means for Solving the Problems]
The object of the present invention can be achieved by the following structural requirements.
[0014]
  An image having a configuration in which a toner image formed on an image carrier is transferred onto a transfer material, and then the transfer material is heated and pressurized with at least two fixing members to fix the toner image on the transfer material. A temperature distribution of the fixing member in a direction orthogonal to the transfer direction of the transfer material via a temperature equalizing member which is a forming apparatus and is provided so as to be able to come into contact with and separate from at least one of the fixing members. In the image forming apparatus configured to average the temperature of any of the fixing members corresponding to the non-sheet-passing area when the size in the direction orthogonal to the conveyance direction of the transfer material used is equal to or less than a predetermined size The control means calculates the rising speed of the output of the temperature sensor for detecting the temperature, the output of the temperature sensor at the time of calculation, and the input image forming finger from the calculated rising speed or falling speed. An image forming apparatus comprising and a remaining number of prints, that allowed to determine the contact possibility of the temperature-equalizing member relative to the fixing member.
[0016]
In any configuration, the fixing member that contacts the temperature equalizing member and the fixing member that detects the end temperature may be the same or different members, depending on the heat capacity, heat conduction, etc. of each member. Although appropriately selected, it is generally desirable that they are the same in terms of accuracy and response.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus 1 including a color printer. As shown in the figure, 10 is a photosensitive drum (hereinafter simply referred to as a drum) that is an image forming body, 11 is a scorotron charger that is a charging means for each color, and 12 is an exposure optical that is an image writing means for each color. The system, 13 is a developing unit as developing means for each color, and 14 is a transfer belt.
[0019]
The drum 10 has, for example, a photosensitive layer (such as a transparent conductive layer, an a-Si layer, or an organic photosensitive layer (OPC)) on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. This is also referred to as a photoconductive layer, and is rotated clockwise as indicated by an arrow while the conductive layer is grounded.
[0020]
The scorotron charger 11, the exposure optical system 12, and the developing unit 13 are set as four sets as image forming means for each color of yellow (Y), magenta (M), cyan (C), and black (K). And arranged in the order of Y, M, C, and K with respect to the rotation direction of the photosensitive drum 10.
[0021]
The scorotron charger 11 has a control grid each maintained at a predetermined potential and a discharge electrode 11a made of, for example, a sawtooth electrode, and is applied to the photosensitive drum 10 by corona discharge having the same polarity as the toner. A uniform potential is applied.
[0022]
The exposure optical system 12 is disposed inside the drum 10 so as to be positioned downstream of the aforementioned scorotron charger 11 in the rotation direction of the photosensitive drum 10.
[0023]
Each exposure optical system 12 is connected to a linear exposure element 12a in which a plurality of LEDs (light emitting diodes) as light emitting elements for image exposure light arranged in parallel to the drum axis in the main scanning direction are arranged in an array. An exposure unit composed of a light converging optical transmission body (trade name: Selfoc lens array) 12b as an image element and a lens holder (not shown), which is attached to a holding member 120.
[0024]
In addition to the exposure optical system 12 for each color, a transfer simultaneous exposure device 12d and a uniform exposure device 12e are attached to the holding member 120, and are integrally accommodated in the base of the drum 10.
[0025]
The exposure optical system 12 exposes the photosensitive layer of the drum 10 from the back according to the image data for each color read by a separate image reading device and stored in the memory, and forms an electrostatic latent image on the drum 10. Form.
[0026]
As the exposure element 12a, a plurality of light emitting elements such as FL (phosphor light emission), EL (electroluminescence), and PL (plasma discharge) arranged in an array can be used in addition to the LED.
[0027]
The light emission wavelength of the exposure element is usually in the range of 780 to 900 nm, which is highly transmissive to Y, M, and C toners, but in this embodiment, image exposure is performed from the back side. The wavelength of 400 to 780 nm, which is not sufficiently transparent to the color toner, may be used.
[0028]
The developing unit 13 includes a developing sleeve 131 formed of a nonmagnetic stainless steel or aluminum material that rotates in the forward direction at the closest point of rotation with respect to the rotation direction of the drum 10, and a developing casing 138. Each contains a one-component or two-component developer of yellow (Y), magenta (M), cyan (C) and black (K).
[0029]
Each developing device 13 is kept in non-contact with the drum 10 with a predetermined gap. By applying a developing bias in which a DC voltage and an AC voltage are superimposed on the developing sleeve 131, non-contact inversion is performed. Development is performed to form a superimposed toner image on the drum 10.
[0030]
14a and 14b are rollers for stretching the transfer belt 14, and 14a receives power from a drive source (not shown) so as to rotate the transfer belt in the direction of the arrow.
[0031]
Reference numerals 15 and 16 denote transfer devices and charge eliminators, which are first and second transfer means arranged opposite to the drum 10 with the transfer belt 14 interposed therebetween. Reference numeral 17 denotes a charge remover for the drum 10 after completion of the transfer process. The AC neutralizer 18 is a cleaning device that cleans the surface of the drum after neutralization, and has a cleaning blade 180.
[0032]
Reference numeral 20 denotes a cassette containing a transfer material P for transferring a toner image formed on the drum 10, and 25 denotes a paper feed roller.
[0033]
On the moving path of the transfer material P, conveyance roller pairs R1 to R5, the transfer belt 14, an image fixing device (hereinafter simply referred to as a fixing device) 30, and the like are attached.
[0034]
Reference numeral 44 denotes an AC static eliminator for paper separation which is disposed so as to face the roller 14a with the transfer belt 14 therebetween.
[0035]
Although the details will be described later, the fixing device 30 includes a halogen heater (halogen lamp) 300, a heating roller 305 that can rotate around the halogen heater, and a heating roller 305 that can rotate while being pressed against the heating roller 305. And a pressure roller 315. T indicates a nip portion.
[0036]
In the figure, reference numeral 46 denotes a separation claw for reliably separating the transferred transfer material P fed integrally with the transfer belt 14 and having a tip close to the surface of the transfer belt 14 on the roller 14a. Is positioned.
[0037]
Reference numeral 91 denotes an operation unit including an operation unit including a start button, a display unit capable of selecting a transfer material size, and the like.
[0038]
The image forming process in the image forming apparatus having the above-described configuration is as follows.
[0039]
When the image formation is started, a drum drive motor (not shown) is started, and the drum 10 is rotated clockwise as indicated by an arrow in FIG. 1, and at the same time, the yellow (Y) scorotron charger 11 is operated to cause the drum 10 to have a predetermined value. Apply potential.
[0040]
Subsequently, image writing by an electric signal corresponding to the first color signal, that is, the Y image data is started via the Y exposure optical system 12, and the static image corresponding to the Y image of the original image is formed on the surface of the drum 10. An electrostatic latent image is formed.
[0041]
The electrostatic latent image is reversely developed in a non-contact state by a Y developing unit 13 to form a yellow (Y) toner image on the drum 10.
[0042]
Next, a potential is applied to the drum 10 from above the Y toner image by the charging action of the magenta (M) scorotron charger 11, and the second exposure signal 12, that is, the M image by the M exposure optical system 12. An electrostatic latent image corresponding to the M image is formed by image writing using an electrical signal corresponding to the data, and magenta is formed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13. The toner image (M) is formed in an overlapping manner.
[0043]
By a similar process, a cyan (C) toner image corresponding to the third color signal is formed by superimposing the cyan (C) scorotron charger 11, the C exposure optical system 12 and the C developing unit 13 together. Further, a black (K) toner image corresponding to the fourth color signal is successively superimposed on the black (K) scorotron charger 11, the K exposure optical system 12, and the K developing device 13. Then, within one rotation of the photosensitive drum 10, a superimposed color toner image of four colors of yellow (Y), magenta (M), cyan (C) and black (K) is formed on the peripheral surface.
[0044]
Image writing on the photosensitive layer of the drum 10 by the Y, M, C, and K exposure optical systems 12 is performed from the inside of the drum 10 through the above-described translucent substrate.
[0045]
Therefore, writing of images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image.
[0046]
The superimposed color toner images formed on the drum 10 by the image forming process are collectively transferred onto the transfer material P by the transfer device 15.
[0047]
At this time, the uniform exposure is performed by energizing the simultaneous transfer exposure device 12d provided in the drum 10 so as to achieve good transfer.
[0048]
The toner remaining on the peripheral surface of the drum 10 after completion of the transfer process is subjected to a static elimination action by the AC static eliminator 17, and then cleaned by a cleaning device 18, whereby the drum surface is used for the next image formation. Provided.
[0049]
In the embodiment, after the cleaning and before the next charging, for example, the uniform exposure device 12e using a light emitting diode is operated to eliminate the history in the previous image formation on the drum surface.
[0050]
The transfer material P on which the color toner image has been formed (transferred) is separated from the transfer belt 14 by the charge eliminating action by the AC charge remover 44 and the separation claw 46, and conveyed to the fixing device 30. The toner image is fixed on the transfer material P.
[0051]
The transfer material P on which image recording has been performed is sent with its front and back reversed, and is discharged to a tray at the top of the apparatus via transport rollers R3, R4, and R5.
[0052]
FIG. 2 is a schematic diagram for explaining the configuration of the heating roller 305, the temperature equalizing member 330, and the like, which are main elements of the fixing device 30 according to the first embodiment.
[0053]
2A is a side sectional view, and FIG. 2B is a plan view of the heating roller 305. FIG.
As shown in the figure, for example, a heating roller 305 including a heating source 300 made of a halogen lamp is provided on the side in contact with the unfixed toner image t on the transfer material P. The heating roller 305 and the pressure roller 315 are pressure-bonded (adhered) with a predetermined pressure, and in operation, rotate in the same direction at the contact portion (nip portion T) while maintaining the pressure-bonded state. To fix.
[0054]
The heating roller 305 includes a roller core 307 made of a cylindrical translucent substrate (glass or the like), a translucent elastic layer (transparent silicon rubber layer) 308 provided on the outer side (outer peripheral surface) of the roller core 307, Further, it has a heat ray absorbing layer (also a release layer for toner) 309 provided on the outside thereof.
[0055]
The pressure roller 315 is configured as, for example, a cylindrical metal pipe 316 using an aluminum material, and a roller in which the outer peripheral surface of the metal pipe 316 is covered with a silicon rubber layer 317.
[0056]
A temperature uniformizing member (hereinafter referred to as a metal roller) 330 has a roller portion 332 and a shaft 331 as main elements, and is configured to be pressure-bonded to the heating roller 305 on the outer peripheral surface of the heat ray absorbing layer 309. The roller 332 is preferably made of aluminum or copper having high thermal conductivity, and application of a heat pipe is also effective. The surface layer of the roller is composed of a thin mold release layer formed of FPA (perfluoroalkoxy resin) or the like. For example, the metal roller 330 is configured to move in the direction indicated by the arrow on the heating roller 305 that is one of the fixing members and to be able to contact and separate.
[0057]
As shown in FIG. 2B, TS1 is a first temperature sensor that is a means for detecting the surface temperature of the heating roller 305, and is disposed at a central position in the longitudinal direction of the heating roller 305.
[0058]
TS2 is a second temperature sensor that is a means for detecting the surface temperature of the non-sheet passing area of the heating roller 305, and is disposed in an area outside the contact area with the transfer material P having a smaller size. The detailed position in the direction orthogonal to the transport direction of the transfer material used is appropriately determined depending on the paper size (transfer material) used and its frequency, the heat transport capability of the metal roller 330, the paper passing speed, and the like. Selected.
[0059]
In this embodiment, the maximum sheet passing width is 300 mm, and the sheet is disposed 30 mm outside the end of the maximum sheet passing area. You may arrange | position in the position symmetrical with 1st temperature sensor TS1 other than the position shown in FIG.2 (b).
[0060]
The first temperature sensor TS1 detects the surface temperature of the heating roller 305, and the detected information is taken into the control unit of the image forming apparatus and is controlled by a temperature controller (see FIG. 5) that is a control unit. A signal is sent and control is performed so that a predetermined value that can be fixed is obtained.
[0061]
The second temperature sensor TS2 detects the surface temperature of the non-sheet passing area of the heating roller 305, and the detection information is information necessary for performing the contact / separation operation of the metal roller 330 to the heating roller 305. It is taken into the control unit of the image forming apparatus.
[0062]
FIG. 5 is a block diagram showing an electrical configuration of the present embodiment.
As shown in the figure, the control unit SE includes a first temperature sensor TS1, a second temperature sensor TS2, a third temperature sensor TS3, a fourth temperature sensor TS4 as detection means, and a CPU based on these detection signals (information). The detection signal is taken in as a control signal via the control unit SE, and the metal roller 330, the metal roller 107, a temperature controller TC as a control means, and an arithmetic unit EN as a control means, which are actuated by the control signal, It is comprised from the controlled part with the counter M which is a control means.
[0063]
The control unit SE has a series of functions such as image data storage means by an image reading device, but is not shown.
[0064]
  FIG.FirstIt is a flowchart for demonstrating this control.
  After selecting the size of the transfer material P to be used in the size selection unit in the display unit arranged in the operation unit 91 and setting (inputting) the number of prints with the numeric keypad, the image from the start button or the like If the feeding of the transfer material P having a predetermined size or less is started from the cassette 20 in accordance with the formation command, the process proceeds to the next step, and if not, the step is returned to the original (ST1).
[0065]
Control means that the number of prints produced in response to the image formation command has reached a predetermined number or more (that is, the actual number of sheets where the surface temperature of the non-sheet passing area of the heating roller 305 is higher than the fixable temperature). If the counter M is determined, the process proceeds to the next step. If the predetermined number has not been reached, the process returns to ST1 (ST2).
[0066]
The discrimination information of the counter M is taken into the control unit SE, the metal roller 330 is operated according to the control signal, and the temperature distribution in the direction orthogonal to the transfer direction of the transfer material P is applied to the heating roller 305. Contact (ST3).
[0067]
If the number of prints reaches the total set number of the counter M, the process proceeds to the next step, and if not, the step is returned to the original (ST4).
[0068]
Information that has reached the total set number is taken into the control unit SE, and the metal roller 330 is operated in accordance with the control signal to be separated from the heating roller 305 (ST5). Then go back to the start.
[0069]
By adopting the above aspect, even when the transfer material P having a predetermined size or less is conveyed in accordance with the image forming command, the contact timing of the metal roller 330 can be appropriately determined and executed, so that useless energy is consumed. The thermal efficiency is improved.
[0070]
  FIG.SecondIt is a flowchart for demonstrating control.
  If the feeding of the transfer material P having a predetermined size or less from the cassette 20 is started in accordance with the image forming command, the process proceeds to the next step, and if not, the step is returned to the original (ST10). In order to determine whether or not the output of the second temperature sensor TS2, that is, the surface temperature of the roller end portion exceeds a predetermined value that can be fixed, the detection output is taken into the control unit SE and temperature control is performed based on the control signal. If it is determined by the device TC that the predetermined value is exceeded, the process proceeds to the next step, and if it does not exceed the predetermined value, the process returns to ST10 (ST11).
[0071]
The metal roller 330 is operated according to the control signal based on the determination result, and is brought into contact with the heating roller 305 so as to average the temperature distribution in the direction orthogonal to the transfer direction of the transfer material P (ST12).
[0072]
Next, if the surface temperature of the heating roller 305 is averaged as a result of the contact of the metal roller 330 and the output of the second temperature sensor TS2 becomes lower than a predetermined value, the process proceeds to the next step, where the temperature exceeds the predetermined value. If so, the step is restored (ST13).
[0073]
Next, the metal roller 330 is operated to move away from the heating roller 305 (ST14). Then go back to the start.
[0074]
Even if the feeding of the transfer material P having a predetermined size or less is started, the basis weight of the transfer material P (grams / m²), The amount of heat carried away by the paper is different, and the rise in the surface temperature of the roller end is different. Therefore, by adopting the above-described mode, it is possible to improve the thermal efficiency without consuming wasteful energy as compared with the case of determining whether the metal roller is contacted or separated with a predetermined number of prints.
[0075]
In this case, the first step (paper size determination) may be omitted because the temperature of the roller end is monitored.
[0076]
  FIG. 6 is a diagram showing the relationship between the output of the second temperature sensor and the time according to the difference in paper thickness.
[0077]
Outputs T1 and T2 of the second temperature sensor TS2 for detecting the temperature of the heating roller 305 corresponding to the non-sheet passing area when the size in the direction orthogonal to the conveyance direction of the transfer material P to be used is a predetermined size or less. Based on the time at that time, the temperature at the end of the roller is predicted by the arithmetic unit EN which is a control means, and the metal roller 330 is brought into contact at a time when the upper limit temperature T3 is not exceeded even if the temperature rises the most (FIG. 6). (See arrow indicating contact).
[0078]
When the paper to be passed (transfer material) is thick, the amount of heat carried away by the paper passing area is large, so the temperature rise at the roller end is large (Fig. 6, graph (1)), but when the paper is thin, The amount of heat carried away by the sheet passing area is relatively small, and the temperature rise at the roller end is moderate (FIG. 6, graph (2)).
[0079]
When the paper is thin, in the present invention, the contact time of the metal roller 330 can be delayed, so that heat loss due to heating of the metal roller 330 can be suppressed to a low level.
[0080]
If the contact of the metal roller 330 is controlled at a predetermined temperature without making such a prediction, it is set to a safer side, so that heat loss increases in the case of thin paper.
[0081]
  FIG. 7 is a diagram showing the relationship between the output of the second temperature sensor and the time depending on whether or not the metal roller is in contact.
[0082]
Outputs T1 and T2 of the second temperature sensor TS2 for detecting the temperature of the heating roller 305 corresponding to the non-sheet passing area when the size in the direction orthogonal to the conveyance direction of the transfer material P to be used is equal to or smaller than a predetermined size. Based on the output and the time at that time, the temperature at the end of the roller is predicted by the arithmetic unit EN which is a control means, and if the metal roller 330 is not brought into contact when the sheet continues, the upper limit temperature T3 is predicted to be exceeded. Even if it is determined that the upper limit temperature T3 cannot be exceeded without contacting the metal roller 330 from the remaining number of sheets to be passed, the metal roller 330 is not contacted (FIG. 7, graph (3)). ).
[0083]
When the contact is controlled by prediction based only on the temperature rise speed without performing such prediction, unnecessary contact is performed, and heat loss lost to the metal roller 330 is increased. (FIG. 7, graph (4)).
[0084]
Similarly, when the output of the second temperature sensor TS2 decreases after the contact of the metal roller 330 and the expected number of prints is expected to end before the upper limit temperature T3 is exceeded, the metal roller 330 is separated. Such control means “determining whether or not contact is possible” described in this claim.
[0085]
By such control, it is possible to suppress an excessive temperature rise at the end of the roller while minimizing heat loss.
[0086]
  Printing is completed in a state where the size of the transfer material P used in the direction orthogonal to the conveyance direction is equal to or smaller than a predetermined size, the metal roller 330 is in contact with the heating roller 305, and the next image formation command is issued. When the temperature controller TC, which is a control means, determines that the temperature of the heating roller 305 exceeds the predetermined value with respect to the non-sheet passing area through the output of the second temperature sensor TS2 In order to continue the contact of the metal roller 330UTo controlThe
[0087]
By adopting this configuration, when the next image formation is larger than a predetermined size, it is possible to prevent a problem that the glossiness of the end portion becomes too high, and the next image formation is a small size. In some cases, it is possible to prevent a problem that the roller end is heated.
[0088]
FIG. 8 is a schematic diagram for explaining a configuration of a heating roller, a metal roller, and the like, which are main elements of the belt-type fixing device according to the second embodiment.
[0089]
As shown in the figure, the fixing device 10A includes, for example, a fixing belt 104 wound around a suspension roller including a heating roller 102 including a heating source 200 made of a halogen lamp and a first pressure roller 103, and the fixing. A temperature equalizing member comprising a second pressure roller 105 provided so as to be able to press and release the first pressure roller 103 via a belt 104, and a metal roller capable of contacting and separating from the first pressure roller 103. 107.
[0090]
The transfer material P carrying the unfixed toner image t after transfer is fed between the first pressure roller 103 and the second pressure roller 105 via the fixing belt 104, and pressure and heat are applied by both rollers. The toner image t can be fixed on the transfer material P by the action.
[0091]
TS3 is a third temperature sensor which is a means for detecting the surface temperature of the heating roller 102, and is arranged at the center position in the longitudinal direction of the heating roller 102.
[0092]
TS4 is a fourth temperature sensor that is a means for detecting the surface temperature of the non-sheet passing area of the fixing belt 104, and is disposed in an area outside the contact area with the transfer material P to be fed.
[0093]
The arrangement location is not limited to the position shown in FIG. 8, but may be in the loop of the fixing belt 104 that has been wound around, or any place where the surface temperature of the first pressure roller 103 in the loop can be detected. .
[0094]
Similar to the temperature sensor TS1, the detection information of the third temperature sensor TS3 is taken into the controller SE of the image forming apparatus so as to be a predetermined value that can be fixed.
[0095]
Similar to the second temperature sensor TS2, the fourth temperature sensor TS4 informs the control unit SE of the image forming apparatus as necessary information for performing the contact / separation operation of the metal roller 107 with the first pressure roller 103. It is supposed to be taken in.
[0096]
For example, the fourth temperature sensor TS4 may be disposed on the second pressure roller 105 as a detection unit of the second pressure roller 105, or may be disposed near the end of the heating roller 102 in the longitudinal direction. May be.
[0097]
Any place that is disposed outside the contact area with the transfer material P to be fed and can detect a temperature rise at the end of the fixing member group such as a roller or a belt may be used. The same applies to the first embodiment.
[0098]
The invention described in the first embodiment can be applied to the second embodiment.
[0099]
By adopting such a configuration, in the case of a small number of prints where the temperature rise at the edge is not a problem in practice, the thermal efficiency decreases due to the contact and separation of the metal roller, and the small size transfer material (paper) of thin paper When the heat capacity is small and the temperature rise at the end of the fixing member is small, the metal roller is unnecessarily brought into contact, and on the contrary, it is possible to prevent a decrease in thermal efficiency that extra heat is taken away by the metal roller.
[0100]
【The invention's effect】
According to the present invention, with a simple configuration, when processing a transfer material having a predetermined size or less with respect to the roller length as a fixing member, it is possible to determine the temperature rise state at the end, the number of print processing sheets, etc. An image forming apparatus with high thermal efficiency can be provided with a configuration in which the contact and separation of the temperature uniform member is controlled in a timely manner with respect to the member.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus including a color printer.
FIG. 2 is a schematic diagram for explaining a configuration of a heating roller, a temperature equalizing member, and the like, which are main elements of the fixing device according to the first embodiment.
FIG. 3 is a flowchart for explaining control according to claim 1;
FIG. 4 is a flowchart for explaining control according to claim 2;
FIG. 5 is a block diagram showing an electrical configuration of the present embodiment.
FIG. 6 is a diagram showing the relationship between the output of the second temperature sensor and the time according to the difference in paper thickness.
FIG. 7 is a diagram showing the relationship between the output of the second temperature sensor and the time depending on whether or not the metal roller is in contact.
FIG. 8 is a schematic diagram for explaining a configuration of a heating roller, a metal roller, and the like, which are main elements of a belt-type fixing device according to a second embodiment.
[Explanation of symbols]
1 Image forming device
P transfer material
30, 10A fixing device
91 Operation unit
200, 300 Heat source
305, 102 Heating roller
315 Pressure roller
330, 107 Metal roller
103 First pressure roller
104 Fixing belt
105 Second pressure roller
TS1 1st temperature sensor
TS2 Second temperature sensor
TS3 Third temperature sensor
TS4 4th temperature sensor
M counter
SE controller
TC temperature controller
EN calculator

Claims (1)

An image having a configuration in which a toner image formed on an image carrier is transferred onto a transfer material, and then the transfer material is heated and pressurized with at least two fixing members to fix the toner image on the transfer material. A temperature distribution of the fixing member in a direction orthogonal to the transfer direction of the transfer material via a temperature equalizing member which is a forming apparatus and is provided so as to be able to come into contact with and separate from at least one of the fixing members. In an image forming apparatus configured to average
If the size in the direction perpendicular to the conveying direction of the transfer material used is Ru der below a predetermined size, controlling the rate of rise of the output of the temperature sensor for detecting the fixing member any temperature that corresponds to the non-paper passing area The temperature equalizing member comes into contact with the fixing member from the calculated ascending speed or descending speed, the output of the temperature sensor at the time of calculation, and the remaining number of prints of the input image formation command. An image forming apparatus that determines whether or not the image is acceptable .

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