JP4614086B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

The present invention relates to a fixing device and an image forming apparatus using the same.

Conventionally, a fixing device including a center heater and an end heater is known (for example, see Patent Document 1). This technology is intended to make the temperature distribution in the longitudinal direction of the fixing roller substantially uniform, which causes fixing unevenness, wrinkles, and hot offset, and is equipped with a plurality of heating means having different light distribution characteristics. A plurality of heating means having a flat area as a light distribution distribution area and an inclined area adjacent to the flat area, and setting the inclined area in the light distribution at the same position between the heating means; The gradients of the inclined regions at the same position are set so as to be substantially equal between the heating means.

Conventionally, the heating unit is provided with a main heating element and an auxiliary heating element, the main heating element is supplied with electric power from the main power supply, and the auxiliary heating element is supplied with electric power from the auxiliary power supply having a capacitor. There is known a fixing device that adjusts the amount of power supplied from a capacitor to an auxiliary heating body in accordance with the temperature of the heating unit when starting the heating of the unit (see, for example, Patent Document 2).

This technology increases the power saving effect, reduces noise due to inrush current and sudden current changes when supplying large power, shortens the rise time, and prevents the temperature from rising too much. A large-capacity electric power is supplied from both the device and the auxiliary power supply device, the heating unit is raised to a predetermined temperature in a short time, and no electric power is supplied to the heating unit during standby. And a charger, a switching device, a temperature detection device, and a control means, wherein the charger charges the capacitor of the auxiliary power supply device with power supplied from the main power supply device, and the switching device charges the auxiliary power supply device and the auxiliary power supply. The power supply from the device to the auxiliary heating element is switched, the temperature detection device detects the temperature of the heating unit, and the control means changes from the auxiliary power supply device to the auxiliary heating element according to the temperature of the heating unit detected by the temperature detection device. The amount of power to be supplied is adjusted.
JP 2002-268421 A JP 2002-184554 A

The present invention develops the above-described technology, and prevents a temperature drop during continuous sheet feeding in a fixing device including a central heating unit and an end heating unit in the axial direction of a fixing member such as a fixing roller. Another object of the present invention is to prevent the temperature rise of the non-sheet-passing portion (uniform temperature) when continuously passing a small-sized recording medium.

In particular, the temperature rise of the non-sheet passing portion is prevented in the fixing device configured to use the power storage means such as a capacitor as an auxiliary power source. When power storage means such as a capacitor is provided as an auxiliary power source, the main power source connected to an external power source such as a commercial power source is configured to feed the end and center heaters, and the auxiliary power source by the power storage means powers the heaters for the entire area. When a recording medium such as paper of a size is continuously fed, the temperature of the central portion of the fixing member decreases. When the temperature of the central portion is detected and the auxiliary power source is controlled, an auxiliary heating body (auxiliary heater) ) Continues to light, the temperature of the non-sheet passing portion of the fixing member tends to rise too much. For this reason, when passing small-size paper or the like, temperature control of the fixing member end is important in order to suppress temperature rise.

The present invention intends to provide a technique for effectively preventing the temperature rise of the non-sheet passing portion in a configuration using a capacitor. Another object of the present invention is to improve the fixing quality at the time of image formation in a low temperature environment.

According to a first aspect of the present invention, there is provided a fixing device including a heating unit that heats one of the pair of rotating bodies, and the image is fixed on the recording medium by passing the recording medium between the pair of rotating bodies. A fixing unit for detecting a temperature in the vicinity of the central portion of the one rotating body in the direction of the rotation axis of the one rotating body; An end portion temperature detecting means for detecting a temperature in the vicinity of the end portion, and the heating portion is disposed in the vicinity of the center portion in the rotation axis direction of the one rotating body, and the one heating portion An end heating unit disposed in the vicinity of the end of the rotating body in the direction of the rotation axis, and a full width heating unit disposed across the center and the end are provided, and includes control means for controlling the operation of the heating unit. In the fixing device When the control unit continuously passes a large-sized width recording medium between the pair of rotating bodies, the control unit controls the full width heating unit based on the output of the center temperature detection unit. , when the continuously printed between the pair of rotating bodies recording medium the width of the small-sized fixing apparatus and controls the overall width heating portion based on an output of the end portion temperature detection means It is.

According to a second aspect of the present invention, in the fixing device according to the first aspect, in the case where a recording medium having a large width is continuously passed between the pair of rotating bodies, the control means includes the central portion. When the full width heating unit is controlled based on the comparison result between the output of the temperature detection means and the first set temperature, and a recording medium having a small size is continuously passed between the pair of rotating bodies. the control means controls the full-width heating unit based on the comparison result between the output and the second set temperature of the end portion temperature detection means, it is the fixing device according to claim.

Which according to the claim 3 is the fixing device according to claim 2, wherein the second set temperature is lower than the first predetermined temperature, it is the fixing device according to claim.

According to a fourth aspect of the present invention, in the fixing device according to the second or third aspect , in the case where a recording medium having a small size is continuously passed between the pair of rotating bodies, the control means includes based on the comparison result between the output end temperature detection means and the second set temperature to control the braking of the full-width heating unit, it is the fixing device according to claim.

According to a fifth aspect of the present invention, in the fixing device according to any one of the second to fourth aspects, the control is performed when a large-sized width recording medium is continuously passed between the pair of rotating bodies. Means controls the end heating section based on the comparison result between the output of the end temperature detecting means and the third set temperature, and a small-sized width recording medium is interposed between the pair of rotating bodies. when continuously printed, the control means control to control the end heating section based on comparison result between the output and the fourth set temperature of the end portion temperature detecting means, and wherein the fixing Device.

According to a sixth aspect of the present invention, in the fixing device according to the fifth aspect, the second set temperature is higher than the fourth set temperature .

Those according to the claim 7, Te fixing device smell of claim 5, wherein the second set temperature and the fourth set temperature are equal, it is the fixing device according to claim.

Those according to the claim 8, in the fixing device according to any one of claims 1 to 7, before Symbol control means, when heating of the heating portion during the upper return elevational, of the end portion temperature detection means output for controlling the power supply to the full width heating unit based on, it is the fixing device according to claim.

According to the ninth aspect of the present invention, in the fixing device according to any one of the first to eighth aspects, the fixing device further includes a power storage device that is charged by a commercial power source and supplies power to the full width heating unit, When the part heating unit and the end heating unit are supplied with power from the commercial power source and continuously pass a large-size width recording medium between the pair of rotating bodies, the control means When the power storage device is controlled to supply power to the full width heating unit based on the output of the part temperature detecting means, and a small-width recording medium is continuously passed between the pair of rotating bodies. The control unit controls the power storage device to supply power to the full width heating unit based on the output of the end temperature detection unit .

Non-passage when those according to the claim 10, in the fixing device according to any one of claims 1 to 9, front Kitan portion temperature detecting means for continuous passing sheet of recording medium width of the small size The fixing device is arranged at a position for detecting the temperature of the paper area .

According to the eleventh aspect of the present invention, there is provided a fixing device that includes a heating unit that heats one of the pair of rotating bodies, and fixes the image on the recording medium by passing the recording medium between the pair of rotating bodies. The heating unit includes a central heating unit that heats the vicinity of the central part corresponding to the sheet passing area through which the small-sized recording medium in the rotational axis direction of the one rotating body passes, and the small-sized heating unit. An end heating unit capable of heating a non-sheet passing area through which a recording medium does not pass, and a sheet passing area through which a large size recording medium having a larger width than the small size recording medium passes, and the center heating unit the There and a heatable overall width heating portion over a region where the end portion heating part from the area of heating is heating, the fixing device comprising a control means for controlling the operation of the heating unit, the one of the one rotary body Of the area heated by the central heating section A central portion temperature detection means for detecting a degree, and a end temperature detection means said end heating section detects the temperature of the area to be heated of the one rotary body, control means, the small size when continuously printed during the recording medium width of the pair of rotating bodies, control to control the overall width heating unit based on the output of the front Kitan portion temperature detecting means, that the fixing device according to claim It is.

The image forming apparatus according to claim 12 is an image forming apparatus using the fixing device according to any one of claims 1 to 11.

  According to the present invention, it is possible to prevent the temperature rise of the non-sheet passing portion in the configuration in which the fixing device is heated using the auxiliary heater.

The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic cross-sectional view of the overall configuration of an image forming apparatus using a fixing device according to the present invention. In the figure, reference numeral 41 denotes an example of an image carrier made of a rotating body, which shows a drum-shaped photoconductor. Around the photosensitive member 41, a developing device 44 including a charging device 42 composed of a charging roller, a mirror 43 constituting a part of the exposure means, and a developing roller 44a in the rotation direction indicated by an arrow in the drawing, A transfer device 48 that transfers the developed image onto transfer paper as the recording material P, a cleaning device 46 that includes a blade 46 a that slides on the peripheral surface of the photoreceptor 41, and the like are disposed. On the photosensitive member 41, the exposure light Lb is scanned through the mirror 43 between the charging device 42 and the developing roller 44a. The irradiation position of the exposure light Lb is referred to as an exposure unit 150.

The transfer device 48 is provided to face the lower surface of the photoreceptor 41. A portion facing the transfer device 48 is a transfer portion 47. A pair of registration rollers 49 are provided at a position upstream of the transfer portion 47 in the rotation direction of the photosensitive member 41. A recording material P guided by a conveyance guide (not shown) and stored in a paper supply tray (not shown) is sent out from the paper supply roller 110 toward the registration roller 49. Further, the fixing device 10 is disposed at a position further downstream in the rotation direction of the photosensitive member 41 of the transfer unit 47.

Image formation in this image forming apparatus is performed as follows. The photosensitive member 41 starts to rotate, and during this rotation, the photosensitive member 41 is uniformly charged by the charging device 42 in the dark, and the exposure unit 150 is irradiated and scanned with the exposure light Lb to form a latent image corresponding to the image to be created. Form. The latent image is moved to the developing device 44 by the rotation of the photoconductor 41, where the developing device 44 visualizes it with toner to form a toner image.

On the other hand, the feeding of the recording material P on the paper feeding tray is started by the paper feeding roller 110, and the recording material P is temporarily stopped at the position of the pair of registration rollers 49 via the conveyance path indicated by the broken line in the drawing, and the photoconductor The delivery timing is set so that the toner image on the toner 41 coincides with the transfer portion 47. Then, the registration roller 49 rotates at a suitable timing, and the recording material P that has been stopped is sent out and conveyed toward the transfer unit 47. Then, the toner image on the photoconductor 41 and the recording material P are matched with each other by the transfer unit 47, and the toner image is transferred onto the recording material P by applying an electric field by the transfer device 48.

The recording material P carrying the toner image in the image forming portion around the photoreceptor 41 is then sent out to the fixing device 10. The toner image on the recording material P is fixed on the recording material P while passing through the fixing device 10, and the recording material P that has been fixed on the toner image is discharged to a paper discharge unit (not shown).

On the other hand, residual toner that is not transferred by the transfer unit 47 and remains on the photoconductor 41 reaches the cleaning device 46 along with the rotation of the photoconductor 41 and is cleaned while passing through the cleaning device 46. The photoconductor 41 prepares for the next image formation in that state.

2 and 3 are conceptual cross-sectional views of a fixing device that can be an object of the present invention, and FIG. 4 is a block diagram schematically showing a circuit configuration of the fixing device of FIGS. As shown in the figure, the fixing device 10 of this example includes a fixing member 14 and a pressure member 15, the heating unit 1 is provided in the fixing member 14, and the fixing temperature detecting means 8 is provided outside the fixing member 14. The fixing device 10 also has a control means 60 for controlling the power supplied from the auxiliary power supply device 3 to the fixing device 10 according to temperature information from the fixing portion temperature detecting means 8 (8a, 8b, 8c) as a control system. have.

The fixing unit temperature detecting means 8 is provided with a central temperature detecting means 8a in the longitudinal direction of the fixing unit (perpendicular to the paper surface in FIG. 2, left and right direction in FIG. 3) in the vicinity of the center where any size recording medium P passes. The end temperature detecting means 8b is arranged at the end of the fixing unit where small size paper does not pass. These temperature detection means are composed of appropriate means such as a thermistor, a thermocouple, an infrared temperature detection device, etc., and send temperature information to the control means 60. Based on the temperature information obtained from the fixing unit temperature detection unit 8, the control unit 60 can control starting, stopping, and increasing / decreasing the amount of power supplied to the heating unit 1 of the fixing device 10. Further, as shown in the circuit configuration of FIG. 4, the illustrated fixing device 10 includes a contact for turning on and off based on a command from the control unit 60 as a power control unit (described later).

The main power supply 2 that supplies power to the image forming apparatus obtains power from a commercial power supply and supplies power to various units in each part of the image forming apparatus. As with general equipment, power can be supplied to each unit or the like in the image forming apparatus by inserting a plug of a power line into a commercial power outlet.

The auxiliary power supply device 3 has power storage means or a power storage device such as an electric double layer capacitor (or an electric double layer capacitor), and adds the power stored by charging from the main power supply device 2 to the power supplied to the main power supply device 2. The large power can be supplied to the image forming apparatus. It should be noted that not only the electric double layer capacitor but also a secondary battery such as Li ion or nickel hydride, a pseudo-capacitance capacitor using oxidation-reduction, or the like can be used for power storage in the auxiliary power supply device 3.

The heating unit 1 in the fixing member 14 includes heating elements 1a, 1b, 1c (AC heaters 1a, 1b, DC heater 1c: hereinafter referred to as main heating members 1a, 1b and auxiliary heating member 1c). In addition to the power supply device 2 and the auxiliary power supply device 3, the charger 4, the charge / discharge switching means 5, the main power control means 6 a and 6 b for controlling the power supply from the main power supply, and the auxiliary power control for controlling the power supply from the auxiliary power supply Means 6c are provided. These power control means 6a, 6b, and 6c are illustrated as on / off switches in the figure, but of course, the present invention is not limited to this, and various types of control elements such as FETs, IGBTs, and triacs can be employed.

The main heat generating member 1a is heated by being supplied with electric power from the main power supply device 2, and heats the central portion which is a position where even a small size paper passes in the axial direction of the fixing member 14. For example, a 100 V, 500 w halogen heater that heats the central portion of about 200 mm width can be used so as to heat the area through which the A4 vertical size recording medium passes.

Similarly, the main heating element 1b generates heat by supplying power from the main power source, and heats the end of the fixing member 14 that is not passed through a small-size recording medium. For example, a halogen heater of about 100 V and 700 w is used so as to heat the end of about 310 mm in width so as to heat the range of A4 landscape paper. A range of about 200 mm in width at the axial center of the fixing member 14 is configured not to generate heat.

On the other hand, the auxiliary heat generating member 1 c generates heat by supplying power from the auxiliary power supply device 3 and can heat almost the entire area of the fixing member 14 in the axial direction. The auxiliary heat generating member 1c can be composed of, for example, a 100V, 1200w halogen heater.

As these heating elements, for example, a halogen lamp or a halogen heater that generates heat by passing a current through a filament formed in a glass tube can be used. However, in the present invention, induction heating is not limited to a halogen lamp or the like. The configuration used may be a configuration using a ceramic heater or a ceramic heater.

The roller base of the fixing member 14 is preferably made of a metal such as aluminum or iron from the viewpoint of durability, deformation due to pressure, or the like. In addition, it is desirable to form a release layer on the roller surface to prevent adhesion with the toner, and it is desirable that the inner surface of the roller be blackened to efficiently absorb the heat of the halogen heater. . Further, although not shown, a belt fixing configuration in which a nip portion is formed by a belt instead of a roller may be used.

The pressure member 15 forms an nip portion between the fixing member 14 by forming an elastic layer such as rubber on the core metal, and a recording material P such as paper on which an unfixed image is formed on the nip portion. By passing the paper, the toner image is fixed on the recording material P by heat and pressure. Further, a nip portion may be formed between the pressure member 15 and the fixing member 14 with a pressure roller having a foam layer. In this case, the heat of the fixing member 14 is not easily transmitted to the pressure roller due to the heat insulating effect of the foam layer, so that the temperature of the fixing member 14 can be increased quickly.

The auxiliary power supply 3 is a power supply for charging the power from the main power supply 2 and supplying power to the auxiliary heat generating member 1c. The power supplied from the main power source can be stored by the charger 4 that supplies the power from the main power source to the auxiliary power source after voltage adjustment or AC / DC conversion, and the auxiliary power is supplied to the heating unit 1 by the charge / discharge switching means 5. Can be supplied.

Specifically, the main power supply device 2 obtains electric power from the outlet of a commercial power supply with the plug 51, and supplies power to the units of each part of the image forming apparatus. In Japan, the current capacity is limited to about 15 A at a voltage of 100 V, and the power from the main power supply 2 is often about 1500 W. It may have functions such as voltage adjustment, AC and DC rectification, and voltage stabilization.

The auxiliary power supply device 3 is configured by connecting a plurality of capacitor cells made of, for example, electric double layer capacitors, and the electric power stored by charging from the main power supply device 2 is larger than that at the time of start-up or continuous paper passing. By adopting a configuration that supplies power when it is desired, it is possible to supply power exceeding the power supplied to the main power supply 2 to the image forming apparatus.

The auxiliary power supply 3 as an example of the configuration is a module of 100 V by connecting 40 capacitor cells having a diameter of 35 mm and a length of about 120 mm in series with 2.5 V and 800 F, an internal resistance of 5 mΩ or less. Is used. In order to ensure the voltage balance of each cell when connected in series, it is possible to ensure long-term stability of operation by providing a voltage balance circuit (not shown). If the internal resistance is 5 mΩ or less, the voltage drop between the terminals of the auxiliary power supply 3 can be smaller than that of a secondary battery such as a lithium battery or a nickel metal hydride battery even at a large current exceeding 20 A at the time of startup. Moreover, since it is a small value among capacitors, large power can be obtained with a smaller number of capacitor cells, which is advantageous in terms of device size and cost.

The auxiliary power supply 3 is a chargeable / dischargeable power supply, and uses an electric double layer capacitor that is a large-capacity capacitor. Unlike the secondary battery, the electric double layer capacitor does not involve a chemical reaction. Has the excellent feature of being long.

In other words, an auxiliary power source using a general nickel-cadmium battery as a secondary battery requires several tens of minutes to several hours even if quick charging is performed. This was not practical because it could be realized only a few times. On the other hand, an auxiliary power source using a capacitor can be rapidly charged for several tens of seconds to several minutes, so the charging time is short, for example, printing is not performed, and there is a margin in the power supply of the main power source. It is possible to charge the battery at a certain time and increase the number of times of heating using the auxiliary power source to a practical number.

Further, since the nickel-cadmium battery has 500 to 1000 charge / discharge cycles, it has a short life as an auxiliary power source for heating, and there is a problem in labor and cost of replacement. On the other hand, an auxiliary power source using a capacitor has a life of 10,000 times or more, and is less deteriorated by repeated charge and discharge. Also, unlike lead-acid batteries, there is no need for liquid replacement or replenishment, so there is almost no maintenance.

In recent years, capacitors that can store a large amount of electric energy have been developed, and their use in electric vehicles and the like is also under consideration. For example, an electric double layer capacitor developed by Nippon Chemi-Con Co., Ltd. has a capacitance of about 2000 F at 2.5 V, and has a sufficient capacity for supplying power for several seconds to several tens of seconds. In addition, NEC Corporation has realized a capacitor of about 80F called a hypercapacitor (trade name). Furthermore, JEOL Ltd. increased the withstand voltage to 3.2 to 3.5 V and increased the energy density to 50 to 75 wh / kg, a technology called nanogate capacitor (trade name) that is 5 to 10 times the conventional one. Announcing.

As described above, the heating unit 1 includes the main heat generating members 1a and 1b and the auxiliary heat generating member 1c. For this, a halogen heater can be used, and a current is passed through the filament formed in the glass tube. It generates heat. However, the present invention is not limited to the halogen lamp or the halogen heater, and induction heating may be used or a ceramic heater may be used.

The electric power supplied to the heating unit 1 as described above is configured to be supplied from the main power supply device 2 to the main heat generating member 1a of the heating unit 1, and power is supplied from the auxiliary power supply device 3 to the auxiliary heat generating member 1c. Can be supplied. In the auxiliary power supply device 3, electric power can be stored in advance by the charger 4, and electric power can be supplied to the auxiliary heat generating member 1c at an arbitrary timing.

In addition to supplying the power from the auxiliary power supply 3 to the heating unit 1 in addition to the main power supply 2, a large amount of power exceeding the power supplied by the main power supply 2 can be supplied to the heating unit 1. For this reason, as shown in FIG. 5A, the temperature rise time until the temperature of the heating unit 1 changes from room temperature to a predetermined temperature is higher than that using only the main power supply device 2 and the main power supply device 2 and auxiliary power supply device. The temperature raising time can be shortened by using 3 at the same time.

Further, as shown in FIG. 5B, when a large amount of heat is taken away by a recording material such as paper by continuous paper passing, even if power supply from the main power supply 2 alone is below a predetermined minimum temperature, the auxiliary power supply When power is supplied from the device 3, the drop can be reduced. For this reason, it is possible to increase the speed of the machine with more paper passing per unit time.

FIG. 6 is a diagram for explaining an example in which a high-speed machine capable of high-temperature temperature rise without a temperature drop of the fixing member even when a thin roller is used. First, in an initial state, power is supplied from a commercial power source, and the auxiliary power supply device 3 having a large-capacity capacitor capable of rapid charging such as an electric double layer capacitor is charged. Since the electrical discharge is small, enough power can be maintained for about one night, and since the outlet is usually kept connected, it is possible to charge from a commercial power source even if the discharge falls below a predetermined value. You can use it when you turn on the main power in the morning.

At the time of start-up, when the temperature of the fixing member 14 such as a fixing roller is raised from room temperature in a short time, in addition to the main power supply device 2, the power of the auxiliary power supply device 3 is supplied to the heating member 1. The total electric power supplied to can be supplied more than when only the main power supply device 2 is used, and therefore the temperature of the heating member 1 can be raised in a short time. For example, an aluminum thin roller having a diameter of 40 mm and a thickness t of 0.7 mm is used as a fixing member, and 1200 W power from the main power source is applied to the main heating members 1 a and 1 b by applying 1200 W heater power from the auxiliary power source. By supplying about 2400 w of electric power as a whole, it is possible to shorten the startup time of 30 seconds with only the main power source to about 15 seconds. FIG. 7 shows that when the power from the auxiliary power supply 3 is not used for the first rise in the morning, it takes longer than the temperature rise at the time of return when the auxiliary power is added to the commercial power.

In addition, since the auxiliary power supply is a capacitor, the supply power gradually decreases from 1200 w due to the voltage drop during power feeding. Due to this feature, it is possible to adopt a configuration in which, when a predetermined time elapses, the power supply becomes very small, and when the temperature is raised to a temperature of 500 ° C. at which paper is ignited, the rate of temperature rise is reduced. Thereby, the structure which implement | achieves temperature rising safely for a short time can be provided.

In order to ensure safety, it is desirable to install a safety device that shuts off the power supply circuit directly by a safety circuit such as a temperature fuse or a thermostat in the event that the system runs out of control.

In addition, as a method of simply increasing the power, it is possible to increase the power by using two commercial power sources, or to use a secondary battery or a fuel cell, but these methods supply a large amount of power almost continuously. Therefore, when the temperature rise time is shortened, the reaction time of these safety circuits is slow and the temperature rise rate cannot be caught up. For this reason, when the safety circuit is activated, the temperature of the heating part becomes too high, and in the worst case, it may ignite. On the other hand, in a configuration using capacitors, the system runs out of control and control is not possible, and even if power supply continues, if the specified power is used up, the heat generation of the heat generating member ends, and the temperature rise stops naturally. Therefore, by using the capacitor as a heat source, it is possible to safely shorten the heating time.

As for the sheet passing, since it is a thin roller, the roller temperature tends to decrease when the number of sheets passed per unit time is large, but it is possible to prevent the temperature drop by supplying auxiliary power in addition to the main power during sheet passing. Therefore, it is possible to provide an easy-to-use image forming apparatus that uses a thin roller even in a high-speed layer and has a short temperature rise time.

In this image forming apparatus, since the temperature drop immediately after the paper can be prevented, a high-speed image formation at 75 cpm is possible even with a thin roller that is normally limited to about 60 cpm.

Regarding charging, power is supplied from the main power supply device 2 to the auxiliary power supply device 3 in a standby state in which power supply from the main power supply device 2 has a margin. When a capacitor is used as an auxiliary power source, the charging time can be shortened to about several minutes. And if it is within several minutes during this charge, since a heating member does not cool, it is unnecessary to use an auxiliary power supply, or it is in time with the charging power to the middle. For this reason, it is not necessary for the next user to wait for charging, and a comfortable function can be provided.

8 and 9 are AC and DC power supply flowcharts when the recording medium is fed in the embodiment of the present invention. FIG. 8 shows temperature control for a large size, and FIG. 9 shows temperature control for a small size. Before entering the control flow, there is a flow for determining the size of the recording medium to be passed. However, since a conventionally known or well-known flow may be used, illustration and description are omitted.

As shown in FIG. 8A, the temperature control when the size of the recording medium P to be passed is large is detected by detecting the temperature Tc at the central portion in the axial direction of the fixing member 14 (step 1), and the set temperature T0 ( For example, the main heating member 1a, which is the central heater, is turned on if Tc <T0 (step 3). If Tc <T0, the main heating member 1a is compared. Is turned off (step 4), and it is checked whether or not the paper has been passed (step 5: a known means can be used as appropriate, the same applies hereinafter). Returning to 1, if the paper passing is completed, the process is terminated. Further, as shown in FIG. 8B, the temperature Tr at the axial end of the fixing member 14 is detected (step 6) and compared with the set temperature T0 (step 7). Based on the result, Tr <T0. If so, the main heating member 1b as an end heater is turned on (step 8), and if Tr <T0, the main heating member 1b is turned off (step 9). Is checked (step 10), the process returns to step 6 if the paper is being passed, and the process is ended if the paper is passed. Further, as shown in FIG. 8C, the temperature Tc at the axial center of the fixing member 14 is detected (step 11) and compared with the set temperature T1 (for example, 180 degrees) (step 12). Based on this, if Tc <T1, the auxiliary heating member 1c, which is a full width heater, is turned on (step 13), and if not Tc <T1, the auxiliary heating member 1c is turned off (step 14). It is checked whether or not the paper has been passed (step 15). If the paper is being passed, the process returns to step 11;

In the temperature control when the size of the recording medium P to be passed is large, the central heater is turned on / off based on the comparison result between the set temperature T0 and the central temperature Tc, and the set temperature T0 and the end temperature Tr are controlled. The end heater is turned on / off based on the comparison result, and the full width heater is turned on / off based on the comparison result between the set temperature T1 and the center temperature Tc. In this embodiment, the power loss is reduced by making the set temperature of the full width heater using the auxiliary power source lower than the set temperature of the central heater.

As shown in FIG. 9A, the temperature control when the size of the recording medium P to be passed is small is detected by detecting the temperature Tc at the central portion in the axial direction of the fixing member 14 (step 21), and the set temperature T0. Contrast (step 22), based on the result, if Tc <T0, the main heating member 1a as the central heater is turned on (step 23), and if Tc <T0, the main heating member 1a is turned off (step T). Step 24) Control is performed to check whether or not the paper has been passed (step 25). If the paper is being passed, the process returns to step 21. If the paper is passed, the process is terminated. Further, as shown in FIG. 9B, the temperature Tr at the axial end of the fixing member 14 is detected (step 26) and compared with the set temperature T2 (for example, 130 degrees) (step 27). Based on this, if Tr <T2, the main heating member 1b, which is an end heater, is turned on (step 28), and if Tr <T2, the main heating member 1b is turned off (step 29). It is checked whether or not the printing has been completed (step 30). If the paper is being passed, the process returns to step 26, and if the paper has been passed, the process is terminated. Further, as shown in FIG. 9C, the temperature Tr at the axial end of the fixing member 14 is detected (step 31) and compared with the set temperature T2 (step 32). Based on the result, Tr <T2 If so, the auxiliary heating member 1c, which is a full width heater, is turned on (step 33), and if Tr <T2, the auxiliary heating member 1c is turned off (step 34). A check is made (step 35). If the paper is being passed, the process returns to step 31. If the paper is passed, the process is terminated.

In the temperature control when the size of the recording medium P to be passed is small, the central heater is turned on / off based on the comparison result between the set temperature T0 and the central temperature Tc, and the set temperature T2 and the end temperature Tr are controlled. The end heater is controlled to be turned on / off based on the comparison result, and the full width heater is turned on / off based on the comparison result between the set temperature T2 and the end temperature Tr.

Next, the operation for preventing temperature rise at the end, which is a feature of the present invention, will be described in detail. FIG. 10A is a diagram illustrating an operation in the case of large-size paper. The horizontal axis of each graph is time, and the vertical axis is the schematic diagram showing the power supply state from the main power source to the central part, the main power source to the end, and the auxiliary power source to the auxiliary heating body as the power supply state at the center and end temperatures. is there. FIG. 10A corresponds to the flowcharts of FIGS. At the time of continuous printing of a large paper passing width, for example, A4 paper in the horizontal direction (width: about 300 mm), the main power supply device 2 supplies the main temperature according to the detected temperature Tc of the central temperature detecting means 8a. Power is supplied to the heat generating member 1a, and power is supplied to the main heat generating member 1b according to the detected temperature Tr of the end temperature detecting means 8b. The auxiliary power supply device 3 supplies power to the auxiliary heat generating member 1c according to the detected temperature Tc of the central temperature detecting means 8a. When a temperature decrease in the central portion is detected, the temperature decrease is prevented by supplying power to the auxiliary heat generating member 1c. To do.

FIG. 10B is a diagram illustrating an operation in the case of a small-size sheet similar to the conventional one. At the time of continuous printing of a size with a small sheet passing width, for example, A4 sheets in the vertical direction (width: about 210 mm), the main power supply device 2 performs main processing according to the detected temperature Tc of the central temperature detecting means 8a. Power is supplied to the heat generating member 1a, and the amount of power supplied to the main heat generating member 1b is controlled according to the detected temperature Tr of the end temperature detecting means 8b. Electric power is supplied from the auxiliary power supply 3 to the auxiliary heat generating member 1c according to the detected temperature Tc of the central temperature detecting means 8a where the temperature tends to decrease. For this reason, power is supplied to the auxiliary heating member 1c for heating the entire sheet passing area, and the temperature of the non-sheet passing area at the end portion is excessively increased.

FIG. 10C corresponds to the flowcharts of FIGS. In the embodiment of the present invention, as shown in FIG. 10 (C), the main power supply device 2 supplies power to the main heating member 1a according to the detected temperature of the central temperature detecting means 8a, and the end temperature detecting means. The power supply amount to the main heat generating member 1b is controlled according to the detected temperature of 8b. Further, power is supplied from the auxiliary power supply device 3 to the auxiliary heat generating member 1c in accordance with the detected temperature Tr of the end temperature detecting means 8b in which the temperature is hardly lowered. For this reason, the power supply to the auxiliary heat generating member 1c for heating the entire sheet passing area is reduced, and therefore, an excessive temperature rise due to heating can be suppressed in the non-sheet passing area at the axial end portion of the fixing member 14. Become.

  FIG. 11 is an AC and DC power supply flowchart when a small-size recording medium is fed in another embodiment of the present invention. 9B and 9C, the set temperature of the main heating member 1b and the auxiliary heating member 1c is the same set temperature T2. In this embodiment, the set temperatures of the main heat generating member 1b and the auxiliary heat generating member 1c are set to different set temperatures. Before entering the control flow, there is a flow for determining the size of the recording medium to be passed. However, since a conventionally known or well-known flow may be used, illustration and description are omitted.

As shown in FIG. 11, the temperature control when the small-sized recording medium P is passed is performed by detecting the temperature Tr at the axial end of the fixing member 14 (step 41) and setting the temperature T2 (for example, 130 degrees). ) (Step 42), based on the result, if Tr <T2, the main heating member 1b as an end heater is turned on (step 43), and if Tr <T2, the main heating member 1b is turned off. (Step 44) Control is performed. Further, the temperature Tr at the axial end of the fixing member 14 detected at step 41 is compared with the set temperature T1 (for example, 180 degrees) (step 45). Based on the result, if Tr <T1, the full width heater is used. A certain auxiliary heat generating member 1c is turned on (step 46), and if Tr <T1 is not satisfied, the auxiliary heat generating member 1c is turned off (step 47) to check whether or not the sheet passing is completed (step 48). If the paper is being passed, the process returns to step 41, and if the paper is passed, the process is ended.

In the temperature control when the size of the recording medium P to be passed is small, the set temperature of the auxiliary heating member 1c is set to the set temperature (for example, 180 degrees) when the size of the recording medium P to be passed is large. In the same manner, by setting the set temperature of the main heat generating member 1b to a low temperature (for example, 130 degrees), the power supply to the auxiliary heat generating member 1c for heating the entire sheet passing area of the fixing member 14 is reduced. In the non-sheet passing region at the axial end portion of 14, it is possible to suppress an excessive temperature rise due to heating.

Further, as a modification of the temperature control when the small-size recording medium P is passed, the temperature control of the auxiliary heating member 1c, which is a full width heater, is performed based on the output of the central temperature detecting means 8a. You may control by temperature lower than the control temperature of time. Specifically, the temperature Tc at the central portion in the axial direction of the fixing member 14 is compared with a set temperature T2 (for example, 130 degrees), and on / off control of power supply to the auxiliary heat generating member 1c is performed based on the result. In the present modification, recording is performed to feed paper in order to supply power to the auxiliary heating member 1c based on a set temperature T2 (for example, 130 degrees) lower than the set temperature T1 (for example, 180 degrees) during large size control. Compared to the case where the size of the medium P is large, the power supply to the auxiliary heat generating member 1c for heating the entire sheet passing area of the fixing member 14 is reduced, and therefore, the non-sheet passing at the axial end portion of the fixing member 14 is reduced. In the region, an excessive temperature rise due to heating can be suppressed.

By the way, even in the fixing device as in the above-described first embodiment, when the sheet is not used for a while after the sheet is passed, the mode shifts to the off mode in order to save power and the fixing roller central portion and the end portion are fixing members. Although the temperature also decreases, the end portion is often in contact with a gear, a side plate or the like in the image forming apparatus, so that heat is radiated more easily than the central portion, and thus the temperature drop is large. In such a state, when the start-up of the return is started, the inventor of the present application conducted an experiment by the same operation as in the past, and the center temperature was able to rise in the set time (10 seconds). Took more than 10 seconds to start, and the temperature could not be raised within the target time.

This is because whether or not to use the power supply from the auxiliary power supply device 3 is determined at the central portion in the axial direction of the fixing member 14 where the temperature does not easily decrease. That is, since the threshold temperature (about 130 ° C.) for turning on the capacitor of the auxiliary power supply device 3 at the time of return startup is compared with the temperature Tc at the axial central portion of the fixing member 14, When there is no auxiliary power supply, there is not enough power and the temperature does not rise within the set time of 10 seconds. Therefore, in the embodiment of the present invention, the threshold temperature (about 130 ° C.) for turning on the capacitor of the auxiliary power supply device 3 is compared with the axial end portion temperature Tr of the fixing member 14 at the time of return startup. These temperature change states are shown in FIG. The conventional temperature change is indicated by a dotted line in FIG. The operation of the embodiment of the present invention is shown by a solid line in FIG.

FIG. 13 is a flowchart when the return start-up is performed from the non-use state after the sheet passing as described above. First, it is checked whether or not the sheet passing is completed (step 51). If the sheet passing is completed, the auxiliary heat generating member 1c which is a DC heater is turned off, and the main heat generating members 1a and 1b which are AC heaters are controlled in temperature. Continue (step 52), and after the elapse of a predetermined time (step 53), both the main heat generating members 1a and 1b are turned off (step 54), become non-use state (off mode), and if there is a return start command ( Step 55) compares the temperature Tc at the central portion in the axial direction of the fixing member 14 with the set temperature T0 (for example, 190 degrees) (Step 56). If Tc <T0, the main heating member 1a as the central heater is turned on. (Step 57), and if Tc <T0, the temperature Tr at the axial end of the fixing member 14 is compared with the set temperature T0 without turning on the main heat generating member 1a (step 58), and Tr < T If so, the main heating member 1b as an end heater is turned on (step 59). If Tr <T0, the main heating member 1b is not turned on, and the temperature Tr at the axial end of the fixing member 14 is set. The temperature T3 (for example, 120 degrees) is compared (step 60). If Tr <T3, the auxiliary heating member 1c, which is a full width heater, is turned on (step 61). If Tr <T3, the process proceeds to the next process. To do.

That is, in the present invention, when the large size paper is passed, heating is performed by the full width heating unit that is fed from the power storage device, thereby preventing a temperature drop during continuous paper feeding, while the small heating load is small. Therefore, even if the central portion is not heated by the full width heating portion fed from the power storage device, the temperature of the central portion is less likely to drop. In addition, if a temperature difference occurs between the hot central part and the low temperature end part during small size paper passing, the end part is heated by the full width heating part fed from the power storage device, so that the central part and the end part are heated. The temperature can be made uniform, so that even when a large-size sheet is started after a small-size sheet is passed, there is little possibility that the start of the sheet passing will be delayed due to the temperature difference between the central part and the end part. Note that the edge temperature control at the time of small-size sheet feeding is for preparing for the subsequent large-size sheet feeding, and therefore does not need to be as high as the central part. In the above embodiment, power supply control from the main power supply device 2 and the auxiliary power supply device 3 to the heating unit 1 is on / off control, but another method, for example, control for adjusting the amount of power supplied per time such as PID control is used. It's okay.

1 is a schematic cross-sectional view of an overall configuration of an image forming apparatus using a fixing device according to the present invention. 1 is a conceptual cross-sectional view of a fixing device that can be an object of the present invention. 1 is a conceptual cross-sectional view of a fixing device that can be an object of the present invention. FIG. 2 is a block diagram schematically showing the circuit configuration of the fixing device shown in FIG. Relationship between usage pattern of main power supply and auxiliary power supply and heating time The figure for demonstrating the example which can implement | achieve the high-speed machine which does not have the temperature fall of the fixing member using a thin roller, and can raise a high speed. The figure which shows the relationship between the heating member temperature change and the power supply etc. to the heating part FIG. 4 is a power supply flow chart when a recording medium is passed in the embodiment of the present invention (temperature control when a large size paper is passed). Similarly, a power supply flow diagram when recording media pass through (temperature control when passing through small sizes) Operation explanatory diagram of temperature rise prevention at the end in the embodiment of the present invention FIG. 6 is a flow chart of power feeding when a recording medium is passed in another embodiment of the present invention (temperature control when passing a small size paper). Temperature change state diagram of fixing member at start-up Flow chart when starting up from a non-use state after passing paper

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating part 1a, 1b Main heat generating member 1c Auxiliary heat generating member 2 Main power supply device 3 Auxiliary power supply device 4 Charger 5 Charge / discharge switching means 6a Main power control means 6b Auxiliary power control means 8, 8a, 8b Fixing temperature detection means 10 Fixing Device 14 Fixing member 15 Pressure member 41 Photoconductor 42 Charging device 43 Mirror 44 Developing device 46 Cleaning device 47 Transfer unit 48 Transfer device 49 Registration roller 60 Control means 110 Paper feed roller 150 Exposure unit Lb Exposure light P Recording material T1 First Set temperature T2 second set temperature Tc temperature at the axial center of the fixing member Tr temperature at the axial end of the fixing member

Claims (12)

A fixing device that includes a heating unit that heats one of the pair of rotating bodies and passes the recording medium between the pair of rotating bodies, thereby fixing an image on the recording medium, and is heated by the heating unit Center temperature detecting means for detecting the temperature in the vicinity of the center of the one rotating body in the rotation axis direction, and end temperature detection for detecting the temperature in the vicinity of the end of the one rotating body in the direction of the rotation axis And a heating part is located near the center part of the one rotating body in the direction of the rotational axis and near the end part of the one rotating body in the direction of the rotational axis. In a fixing device including an end heating unit arranged and a full width heating unit arranged over the central part and the end part, and including a control unit for controlling the operation of the heating unit, the control unit has a large size width When the recording medium is continuously passed between the pair of rotating bodies, the full width heating unit is controlled based on the output of the center temperature detecting means, and the recording medium having a small width is transferred to the pair of rotating bodies. when continuously printed during the rotating body, which controls the overall width heating portion based on an output of the end portion temperature detection unit, a fixing device, characterized in that. 2. The fixing device according to claim 1, wherein when the recording medium having a large width is continuously passed between the pair of rotating bodies, the control unit outputs the output of the central part temperature detection unit and the first temperature detection unit. The full width heating unit is controlled based on a comparison result with a set temperature, and when the recording medium having a small size is continuously passed between the pair of rotating bodies, the control unit includes the end portion. A fixing device , wherein the full width heating unit is controlled based on a comparison result between an output of the temperature detecting means and a second set temperature. The fixing device according to claim 2, wherein the second set temperature is lower than the first predetermined temperature, the fixing device, characterized in that. 4. The fixing device according to claim 2 or 3 , wherein when the recording medium having a small size is continuously passed between the pair of rotating bodies, the control means outputs the output of the end temperature detecting means and the output of the end temperature detecting means. A fixing device , wherein the full width heating unit is controlled based on a comparison result with a second set temperature. 5. The fixing device according to claim 2 , wherein when the recording medium having a large width is continuously passed between the pair of rotating bodies, the control unit includes the end temperature detecting unit. In the case where the edge heating unit is controlled based on the comparison result between the output and the third set temperature, and a small-width recording medium is continuously passed between the pair of rotating bodies, The fixing device , wherein the control unit controls the end heating unit based on a comparison result between the output of the end temperature detecting unit and a fourth set temperature. 6. The fixing device according to claim 5 , wherein the second set temperature is higher than the fourth set temperature . Te fixing device smell of claim 5,
The second set temperature and the fourth set temperature are equal;
A fixing device. In the fixing device according to any one of claims 1 to 7 ,
A fixing device before Symbol control means, when heating of the heating portion during the upper return elevational, controls the power supply to the full width heating unit based on the output of said end portion temperature detection means, characterized in that. The fixing device according to any one of claims 1 to 8, the fixing device is charged by the commercial power source, further comprising a power supply the electrical storage device to the full width heating unit, the said central portion heating part end heating section In the case where a large-sized recording medium is continuously fed between the pair of rotating bodies, the control means is based on the output of the central temperature detecting means. When controlling the power storage device to supply power to the full width heating unit and continuously passing a small-size width recording medium between the pair of rotating bodies, the control means includes the end portion A fixing device, wherein the power storage device is controlled to supply power to the full width heating unit based on an output of a temperature detecting means . The fixing device according to any one of claims 1-9, before Kitan unit temperature detecting means, a position for detecting the temperature of the non-sheet passing area in the case of continuous passing sheet of recording medium width of the small size A fixing device that is arranged . A fixing device that includes a heating unit that heats one of a pair of rotating bodies, and that fixes an image on the recording medium by passing the recording medium between the pair of rotating bodies.
The heating unit heats the central portion corresponding to the paper passing area through which the small size recording medium in the rotation axis direction of the one rotating body passes, and the small size recording medium passes. A non-sheet-passing area, an end heating section capable of heating a sheet-passing area through which a large-sized recording medium having a width larger than that of the small-sized recording medium passes, and an area heated by the central heating section A fixing device including a full width heating unit that can be heated over a region heated by the end heating unit, and including a control unit that controls the operation of the heating unit .
A central part temperature detecting means for detecting a temperature of a region heated by the central part heating part of the one rotating body;
An end portion temperature detecting means for detecting a temperature of a region heated by the end portion heating portion of the one rotating body;
With
Control means, when the continuously printed between the pair of rotating bodies recording medium the width of the small-sized control to control the overall width heating unit based on the output of the front Kitan portion temperature detecting means a fixing device, characterized in that. An image forming apparatus using the fixing device according to claim 1.