JP2008096862A - Fixing device, image forming apparatus - Google Patents

Abstract

In a fixing device that has an auxiliary power supply and performs power assistance from the auxiliary power supply, a heating member and a pressure member are quickly and reliably separated.
A fixing nip is formed between a heating roller and a fixing roller 1 heated by a main heating element 2a and an auxiliary heating element 2b that generate heat upon receiving power supply from a main power supply 4a and an auxiliary power supply 4b. In the fixing device having the pressure roller 10 for performing the above operation, the contact / separation mechanism 20 using a solenoid 12 as a driving source for contacting and separating the fixing roller 1 and the pressure roller 10 as a driving source, and the heat generation from the auxiliary power supply device when the device is warmed up. Auxiliary power supply control means 3 for supplying power to the body is provided, and the contact / separation mechanism 20 separates the fixing roller 1 and the pressure roller 10 during warm-up. The contact / separation mechanism 20 is connected to the fixing roller 1 in the standby mode, in the off mode, when the temperature of the pressurizing unit is lower than the specified temperature, and when the amount of power stored in the auxiliary power supply is lower than the specified value. The pressure roller 10 is separated.
[Selection] Figure 2

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly to a fixing device and an image forming apparatus in which a heating element of a heating unit is supplied with power from a main power supply device and an auxiliary power supply device.

  As a fixing device of an image forming apparatus, there is a fixing device that includes a heating member and a pressure member that form a nib portion, and uses a main power source such as a commercial power source and an auxiliary power source such as a power storage device as a heating unit of the heating member. Some of such fixing devices shorten the warm-up time by supplying power from an auxiliary power supply in addition to the main power supply during warm-up.

  In Patent Document 1, in a fixing device that fixes toner on a sheet to the sheet by heat and pressure, a heat source that generates heat by energization, a fixing member or a heating member that is heated by the heat source, and stored power Another fixing device is described that includes a power storage device that drives at least one of the heat generation sources for a predetermined time during start-up, and a charging device that charges the power storage device with power from the commercial power source.

  In such a fixing device, the heating member and the pressure member are normally in pressure contact, and the heating means heats the pressure means in pressure contact with the heating member at the time of warm-up. It will take time to heat.

To cope with this, it is conceivable to separate the heating member and the pressure member during warm-up. Japanese Patent Application Laid-Open No. H10-228561 describes a technique in which the press contact between the heating member and the pressurizing member can be released by a contact / separation mechanism using an eccentric cam in order to eliminate the problem due to the permanent deformation of the pressurizing member over time.
Japanese Patent No. 36709777 JP 2005-201917 A

  However, the technique of Patent Document 2 is eccentric in order to avoid the occurrence of a malfunction due to permanent distortion when the pressure member made of an elastic body is given a high pressure over a long period of time at the nip portion with the heating member. A mechanism for releasing the pressure contact between the pressure member and the heating member using a cam is provided, and since the eccentric cam is used, the release amount for releasing the pressure contact is insufficient, and the heating member The pressure member cannot be completely separated.

  Further, in order to release pressure by rotating the eccentric cam, a complicated mechanism such as a mechanical drive means (drive motor and gear mechanism for drive transmission) for driving the cam is required. Therefore, the heating unit and the pressurizing unit cannot be contacted or separated instantaneously.

Accordingly, the present invention provides a fixing device that has an auxiliary power supply device and shortens the warm-up time of the heating member by substituting electric power from the auxiliary power supply device during warm-up. It is an object of the present invention to provide a fixing device capable of separating a pressure member.

  According to a first aspect of the present invention, in the fixing device, a main power supply device, an auxiliary power supply device, a heating element that generates heat upon receiving power supply from the main power supply device or the auxiliary power supply, and a heating unit that is heated by the heating element. And a pressurizing unit that forms a fixing nip between the heating unit and a contact / separation mechanism using a solenoid as a drive source for contacting and separating the pressurizing unit and the heating unit, and a worm of the device And a control means for supplying power from the auxiliary power supply to the heating element at the time of up, and the contact / separation mechanism separates the heating section and the pressurizing section at the time of warm-up. is there.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the contact / separation mechanism separates the heating unit and the pressurizing unit in a standby state after the end of the job.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the contact / separation mechanism includes the heating unit and the pressurizing unit in an off mode in which power supply to the heating element is interrupted. Are separated from each other.

  According to a fourth aspect of the present invention, there is provided the fixing device according to any one of the first to third aspects, further comprising a temperature detecting unit that detects a temperature of the pressurizing unit, and the contact / separation mechanism has a temperature of the pressurizing unit equal to or lower than a specified temperature. In this case, the heating part and the pressure part are separated from each other.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the contact / separation mechanism adds the heating unit to the heating unit when the amount of electric power stored in the auxiliary power supply device is a specified value or less. The pressure part is separated from the pressure part.

  A sixth aspect of the present invention is an image forming apparatus comprising the fixing device according to any one of the first to fifth aspects.

  According to the fixing device and the image forming apparatus according to the present invention, the heating element is heated by the auxiliary power source during warm-up, and the pressurizing unit and the heating unit are separated and contacted by the contact / separation mechanism using the solenoid as the driving source. Therefore, the heating member and the pressure member can be separated quickly and reliably, and the heating means can be heated quickly.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a sectional view conceptually showing an image forming apparatus which is an electrophotographic copying machine according to the present invention. The image forming apparatus according to the present embodiment mainly includes a reading unit 111 that reads a document, an image forming unit 112 that forms an image, an automatic document feeder (ADF) 113, and a document that stacks documents sent from the ADF 113. A paper discharge tray 114, a paper supply unit 119 including paper supply cassettes 115 to 118, and a paper discharge unit (discharge tray 120) for stacking recording paper are configured.

Then, when the document D is set on the document table 121 of the ADF 113 and an operation unit (not shown), for example, a print key is pressed, the uppermost document D is sent out in the direction of the arrow B 1 by the rotation of the pickup roller 122. Then, by the rotation of the document conveying belt 123, the paper is fed onto the contact glass 124 fixed to the image reading unit 111 and stops there. The image of the document D placed on the contact glass 124 is read by a reading device 125 positioned between the image forming unit 112 and the contact glass 124. The reading device 125 includes a light source 126 that illuminates the document D on the contact glass 124, an optical system 127 that forms an image of the document, a photoelectric conversion element 128 that includes a CCD that forms an image of the document, and the like. After the image reading is completed, the document D is transported in the direction of arrow B2 by the rotation of the document transport belt 123 and discharged onto the document discharge tray 114. In this way, the document D is fed one by one onto the contact glass 124 and the document image is read by the image reading unit 111.

On the other hand, inside the image forming unit 112, a photoreceptor 130 as an image carrier is disposed. The photoconductor 130 is driven to rotate clockwise in the drawing, and the charging device 131 charges the surface to a predetermined potential. Further, the writing unit 132 emits a laser beam L that is light-modulated in accordance with image information read by the reading device 125, and the surface of the charged photoreceptor 130 is exposed with the laser beam L. An electrostatic latent image is formed on the surface of the body 130. When the electrostatic latent image passes through the developing device 133, the electrostatic latent image is transferred to the recording material 9 fed between the photosensitive member 130 and the transfer device 134 by the opposing transfer device 134. The surface of the photoreceptor 130 after the toner image transfer is cleaned by a cleaning device 135.

A plurality of paper feed cassettes 115 to 118 arranged at the lower part of the image forming unit 112 contain recording material 9 such as paper, and the recording material 9 is fed from any of the paper feed cassettes 115 to 118 in the direction of arrow B3. The toner image formed on the surface of the photoreceptor 130 as described above is transferred onto the surface of the recording material 9. Next, the recording material 9 is passed through the fixing device 140 in the image forming unit 112 as indicated by an arrow B4, and the toner image transferred to the surface of the recording material 9 by the action of heat and pressure is fixed. The recording material 9 that has passed through 136 is conveyed by the discharge roller pair 137, discharged to the discharge tray 120 as shown by an arrow B5, and stacked.

  Next, the fixing device according to the embodiment will be described. FIG. 2 is a schematic configuration diagram illustrating the configuration of the fixing device according to the embodiment. The fixing device 140 includes a pressure roller 10 that is a pressure member, and a fixing roller 1 that is a heating member that forms a nip portion between the pressure roller 10. In the fixing roller 1, a main heating element 2a and an auxiliary heating element 2b are incorporated as heating elements. Further, the pressure roller 10 is provided with a spring 14 that biases the pressure roller 10 toward the fixing roller 1.

  The pressure roller 10 is provided with a contact / separation mechanism 20 for separating the pressure roller 10 from the fixing roller 1. The contact / separation mechanism 20 includes a separation lever 13 and a solenoid 12 that drives the separation lever 13. The solenoid 12 converts electric energy into a linear motion by a magnetic force generated by passing a current through the electromagnetic coil.

  When the solenoid 12 is driven as indicated by an arrow in FIG. 2, the pressure roller 10 is brought into contact with the fixing roller 1 or the pressure roller 10 is separated from the fixing roller 1. That is, when the pressure roller 10 is separated from the fixing roller 1, the solenoid 12 moves the pressure roller 10 downward to a positional relationship where they do not contact each other.

  Here, in order to form the nip portion, the spring 14 needs a very high repulsive force, and more force is necessary to separate the fixing roller 1 and the pressure roller 10. Therefore, the separation lever 13 can be separated by using the lever principle (lever ratio) even if the suction force of the solenoid 12 is not so high.

  The solenoid is used as the contact / separation mechanism 20 for the following reason. That is, since the contact / separation operation can be performed instantaneously, there is almost no time lag with respect to the contact / separation operation signal, and a stable repetitive operation can be obtained. Since the recording material 9 can be contacted and separated instantaneously, the recording material 9 can be brought into contact immediately before entering the nip portion, and can be brought into contact immediately after entering the nip. It becomes possible to separate immediately after passing through the nip portion. Further, as the time required for contact / separation is earlier, the amount of heat transfer from the fixing roller 1 to the pressure roller 10 can be reduced, so that more energy can be saved and the temperature drop of the fixing roller 1 can be avoided. Good image quality can be obtained.

  Further, the pressure roller 10 is provided with temperature detecting means 8 for detecting the temperature of the pressure roller 10 in contact or non-contact. It is desirable that a release layer such as PFA or PTFE is formed on the outermost layer of the fixing roller 1.

  The installation position of the temperature detecting means 8 is desirably as far as possible from the nip portion (in the circumferential direction). The farther from the nip portion, the lower the temperature of the pressure roller 10 (the pressure roller 10 has the highest temperature at the nip portion that is in direct contact with the heating roller, and the lowest temperature at the position opposite 180 degrees). If the temperature is detected at this position, the temperature is detected at a place where there is the most temperature difference from the fixing roller 1, and it is equivalent to grasping the maximum value as the amount of heat transfer during warm-up. Generally, it is desirable to install it at a position 180 degrees opposite to the nip portion in the circumferential direction.

  Next, a heat generation control circuit of the fixing device will be described. FIG. 3 is a block diagram showing a heat generation control circuit of the fixing device. The heat generation control circuit of the fixing device includes a main power supply 4a that supplies power to the main heating element 2a disposed on the fixing roller 1, an auxiliary power supply 4b that supplies power to the auxiliary heating element 2b, and the power of the main power supply 4a. Main switch 6 for turning on / off supply, charger 5 for charging auxiliary power supply 4b with main power supply 4a, switching means 7 for switching charge / discharge of auxiliary power supply 4b, temperature detection means 8, and auxiliary Auxiliary power control means 3 for controlling the discharge of the power supply device 4b is provided.

  The fixing roller 1 includes a main heating element 2a that generates heat by the power supplied from the main power supply 4a, and an auxiliary heating element 2b that generates heat by the power supplied from the auxiliary power supply 4b. The main power supply device 4a receives power supply from a commercial power supply in the image forming apparatus provided with the heating roller. The main power supply device 4a has a function of adjusting, for example, the power supplied from an outlet or the like to a voltage corresponding to the fixing roller 1.

  The auxiliary power supply device 4b is an electric double layer capacitor and includes a chargeable / dischargeable capacitor C. Unlike the secondary battery such as a storage battery, this air double layer capacitor has an excellent feature because it does not involve a chemical reaction.

  In an auxiliary power supply using a general nickel-cadmium battery as a secondary battery, charging takes a long time of several tens of minutes to several hours even if rapid charging is performed, but in an auxiliary power supply using a capacitor, several minutes are required. When the standby state and the heating state are repeated within the same time, by using an auxiliary power supply device using a capacitor, power can be reliably supplied from the auxiliary power supply device 4b at the start-up of heating. The fixing roller can be raised to a predetermined temperature in a short time.

  FIG. 4 is a graph showing discharge characteristics of the auxiliary power supply device. When a large amount of power is stored in the auxiliary power supply 4b, the amount of power during discharge is high (corresponding to the initial stage of discharge in FIG. 4), but when almost no power is stored, the power during discharge is very small ( Therefore, when electric power is not stored, almost no power can be expected from the auxiliary power supply 4b to the heating element. That is, at this time, the heating unit must be heated by supplying power only from the main power supply device 4a, and it is necessary to reduce the heat capacity of the member that raises the temperature as much as possible. When the pressure roller 10 is in contact with the fixing roller 1, the heat capacity of the fixing roller 1 is increased, which is disadvantageous for shortening the warm-up time. Therefore, it is most desirable to reduce the heat capacity of the heating roller and reduce the warm-up time by separating the pressure roller 10 when the power supplement from the auxiliary power supply 4b cannot be expected so much.

  Further, since the nickel-cadmium battery has an allowable number of charge / discharge repetitions of about 500 to 1000 times, it has a short life as an auxiliary power supply for heating, and there is a problem in replacement labor and cost. The auxiliary power supply device 4b using a capacitor has an allowable number of repetitions of charge / discharge of several million times or more, is less deteriorated due to repeated charge / discharge, and does not require liquid replacement or replenishment unlike a lead storage battery. Therefore, it requires little maintenance and can be used stably for a long time.

  An electric double layer capacitor does not have a dielectric, and uses the absorption and desorption reactions (charging and discharging) of the ion adsorbing layer of the electric double layer in which the charge of ions or solvent molecules formed at the solid electrode and solution interface is concentrated. It has excellent features such as strong resistance to repeated charge and discharge, long life, no maintenance, environmental friendliness, and high charge and discharge efficiency. Recently, capacitance is tens of thousands of F, energy density is several. A large capacity of 10 wh / kg has been developed, and the capacity is being increased further.

  The main switch 6 is for turning on / off the power supplied from the main power supply 4a to the main heating element 2a, and the charger 5 is a voltage corresponding to the auxiliary power supply 4b with the power supplied from the main power supply 4a. And the capacitor C is charged.

  Next, the basic operation of such a heating device will be described. In this embodiment, power is supplied from the auxiliary power supply 4b to the auxiliary heating element 2b when the apparatus is warmed up, and the contact / separation mechanism 20 separates the fixing roller 1 and the pressure roller 10 by the solenoid 12 during warmup. Let As a result, the amount of heat generated by the fixing roller 1 is increased, heat is prevented from being transferred from the fixing roller 1 to the pressure roller 10, and the warm-up time is shortened.

  In the embodiment, the solenoid 12 of the contact / separation mechanism 20 separates the fixing roller 1 and the pressure roller 10 during standby after the job ends. This avoids heat transfer from the heating member to the surroundings during standby, and reduces the amount of power supplied to the heating element during standby.

  Further, in this embodiment, the solenoid 12 of the contact / separation mechanism 20 separates the fixing roller 1 and the pressure roller 10 in the off mode when the power supply to the main heating element 2a and the auxiliary heating element 2b is cut off. Let This prevents heat transfer from the heating member to the pressure member during the next warm-up, thereby shortening the warm-up time.

  In the off mode, that is, in the standby state after the job, power is supplied to the heating element to keep the heating part temperature. In this off mode, control to keep the heating part temperature constant is performed. There is no power supply to the heating element. For this reason, the temperature of the heating member and the pressure member decreases due to the natural heat dissipation action. When the main body power key of the image forming apparatus is pressed, power supply to the heating element is started in the same way as in normal warm-up, and the temperature is increased until the heating unit temperature reaches the specified temperature.

  Further, in this embodiment, the solenoid 12 of the contact / separation mechanism 20 is connected to the fixing roller 1 and the pressure roller when the temperature detection means 8 provided on the pressure roller 10 reduces the temperature of the pressure roller 10 to a specified temperature or lower. 10 is separated. As a result, when the pressure roller 10 is cooled and the temperature difference with the fixing roller 1 increases and the amount of heat transfer increases, the pressure roller 10 is separated from the fixing roller 1 to prevent the temperature of the fixing roller 1 from decreasing. , To shorten the warm-up time.

  In this embodiment, the solenoid 12 of the contact / separation mechanism 20 separates the fixing roller 1 and the pressure roller 10 when the amount of power stored in the auxiliary power supply device 4b that supplies power is small. When the power of the auxiliary power supply 4b is low, the total amount of power supplied from both the main power supply 4a and the auxiliary power supply 4b is reduced, so that the amount of heat generated by the fixing roller 1 is reduced. In such a state, the heating member and the pressure member are separated so that the warm-up time can be shortened.

  An example of the operation of the fixing device 140 that is controlled as described above will be described. In this example, the image forming apparatus sequentially performs warm-up, paper passing, standby, off mode, return, and standby. FIG. 5 is a graph showing the temperature of the fixing roller of the fixing device according to the embodiment.

  First, before the image forming apparatus is in an operating state, the switching device 7 connects the charger 5 to the auxiliary power supply device 4b and charges the capacitor C of the auxiliary power supply device 4b.

  When the copy switch is pressed in this state, the image forming apparatus operates and enters a warm-up state. In the warm-up state, the solenoid 12 separates the fixing roller 1 and the pressure roller 10 from each other. The image forming apparatus turns on the main switch 6 to supply power from the main power supply 4a to the main heating element 2a, and simultaneously switches the switching device 7 to supply power from the auxiliary power supply 4b to the auxiliary heating element 2b. A large amount of power is supplied to the fixing roller 1. In this way, when heating of the fixing roller 1 is started, a large amount of electric power is supplied from both the main power supply device 4a and the auxiliary power supply device 4b to the fixing roller 1, and the pressure roller 10 contacts the fixing roller 1. Therefore, the fixing roller 1 can be raised to a predetermined temperature in a short time (warm-up in FIG. 5).

  When the transfer process is completed in the image forming apparatus, the recording material 9 onto which the toner image has been transferred is conveyed to the nip portion between the fixing roller 1 and the pressure roller 10 in contact therewith, and the fixing roller heated to a constant temperature. The toner is heated and melted by 1 and fixed on the recording material 9 as a toner image. At this time, the main heating element 2a and the auxiliary heating element 2b of the fixing roller 1 are supplied with power from the main power supply device 4a and the auxiliary power supply device 4b, thereby increasing the temperature of the fixing roller 1 and the auxiliary power supply device 4b. By controlling on / off of the power supplied from the fixing roller 1, the temperature of the fixing roller 1 is prevented from becoming too high, and the fixing temperature is maintained at a constant temperature or a desired temperature, or is controlled so as to exhibit a required temperature change. As a result, the toner is stably heated and melted, and a good quality toner image is fixed on the recording material 9 (paper passing in FIG. 5).

  When the paper feeding stops, the image forming apparatus enters a standby state. During this standby, the solenoid 12 separates the fixing roller 1 and the pressure roller 10 as described above. In this state, after a predetermined time elapses after the auxiliary power supply 4b supplies power to the auxiliary heating element 2b of the fixing roller 1 and starts heating, the auxiliary power control means 3 starts from the auxiliary power supply 4b. The power supplied to the auxiliary heating element 2b is cut off to prevent the fixing roller 1 from overheating and maintained at a predetermined temperature. The electric power supplied from the auxiliary power supply 4b to the auxiliary heating element 2b decreases as time passes after the supply is started (standby in FIG. 5).

  When a predetermined time has elapsed from the standby state, the image forming apparatus enters an off mode. In the off mode, the power supply to the main heating element 2a and the auxiliary heating element 2b is cut off. In the off mode state, the solenoid 12 separates the roller 1 and the pressure roller 10 from each other. This prevents heat transfer from the heating member to the pressurizing member during the next warm-up, thereby shortening the next warm-up time.

  Next, when the copy switch is pressed during the off mode, the image forming apparatus starts operation and enters the return mode. In this state, as in the warm-up state, the fixing roller 1 and the pressure roller 10 are separated from each other, and the main switch 6 is turned on to supply power from the main power supply device 4a to the main heating element 2a. The apparatus 7 is switched to supply power from the auxiliary power supply 4b to the auxiliary heating element 2b, and supply a large amount of power to the fixing roller 1 (return in FIG. 5). As described above, the main heating element 2a and the auxiliary heating element 2b built in the fixing roller 1 are supplied with power from the main power supply device 4a and the auxiliary power supply device 4b to increase the temperature of the fixing roller. Can be rapidly raised to a predetermined fixing temperature. In this example, in the standby state, the sheet is not passed and the standby mode is set and standby is performed.

  In the image forming apparatus according to the embodiment, the fixing roller 1 and the pressure roller 10 are always used when the temperature of the pressure roller 10 is lowered to a specified temperature or lower by the temperature detection unit 8 provided in the pressure roller 10. Separate. Further, the fixing roller 1 and the pressure roller 10 are separated from each other when the amount of power stored in the auxiliary power supply 4b is small.

  According to this embodiment, the heating element is heated by the auxiliary power source at the time of warm-up, and the fixing roller and the pressure roller are separated by the contact / separation mechanism using the solenoid as the driving source. Can be separated from the pressure member and the heating means can be quickly heated, in standby mode, in the off mode, when the temperature of the pressure unit falls below a specified temperature, and to the auxiliary power supply device Since the fixing roller and the pressure roller are separated from each other when the stored electric energy is equal to or less than the specified value, the energy consumption can be suppressed.

  Further, a time for cutting off the electric power supplied from the auxiliary power supply device 4b to the auxiliary heating element 2b is determined according to the reduction amount of the supplied electric power. If the electric power supplied to is cut off, it is possible to prevent deterioration of each component of the surrounding circuit and electromagnetic noise that occur when the electric power is cut off in a state where a large electric power is being supplied.

  As described above, according to the present invention, since the solenoid-type contact / separation mechanism that can completely separate the heating member and the pressure member is provided, the heating member that causes the warm-up time to be extended. The number of contact objects can be reduced, the heating part temperature can be raised to the specified temperature in a short time, and the job can be started, so that usability can be improved.

  Further, according to the present invention, since the number of heating element lightings and the lighting time can be reduced during standby, an energy saving effect can be obtained.

  Further, according to the present invention, since the heating member and the pressure member are separated from each other in the off mode, the temperature of the heating unit can be increased in a short time when the next return from the off mode is performed, and the warm-up time can be shortened.

  Further, according to the present invention, the pressure member is separated from the heating member when the pressure member falls below a certain temperature. Therefore, when the pressure member cools down and the temperature difference from the heating member increases, that is, from the heating member. It is possible to shorten the warm-up time when the amount of heat transfer increases.

  Further, according to the present invention, when the amount of electric power stored in the auxiliary power supply device is small and a large amount of power cannot be supplied from the auxiliary power supply device during warm-up, the heating member and the pressure member are separated from each other to separate the worm. Uptime can be shortened.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. 1 is a schematic configuration diagram illustrating a configuration of a fixing device according to an embodiment. FIG. 3 is a block diagram illustrating an electrical configuration of a fixing device according to an embodiment. 6 is a graph showing discharge characteristics of an auxiliary power supply device of a fixing device according to an example. 3 is a graph showing the temperature of a fixing roller of a fixing device according to an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 2a Main heating element 2b Auxiliary heating element 3 Auxiliary power supply control means 4a Main power supply apparatus 4b Auxiliary power supply apparatus 5 Charger 6 Main switch 7 Switching device 8 Temperature detection means 9 Recording material 10 Pressure roller 12 Solenoid 13 Separation lever 14 Spring 111 Unit 112 Image forming unit 113 Automatic document feeder (ADF)
114 Document discharge trays 115 to 118 Paper feed cassette 119 Paper feed unit 120 Paper discharge tray 121 Document table 122 Pickup roller 123 Document transport belt 124 Contact glass 125 Device 126 Light source 127 Optical system 128 Photoelectric conversion element 130 Photoconductor 131 Charging device 132 Writing unit 133 Developing device 134 Transfer device 135 Cleaning device 137 Discharge roller pair 140 Fixing device

Claims (6)

A fixing nip between a main power supply device, an auxiliary power supply device, a heating element that generates heat upon receiving power from the main power supply device or the auxiliary power supply, a heating unit that is heated by the heating element, and the heating unit In a fixing device having a pressure unit for forming
A contact / separation mechanism using a solenoid as a drive source to contact and separate the pressure unit and the heating unit;
Control means for supplying power from the auxiliary power supply to the heating element when the apparatus is warmed up,
The fixing device according to claim 1, wherein the contact / separation mechanism separates the heating unit and the pressure unit during the warm-up.   The fixing device according to claim 1, wherein the contact / separation mechanism separates the heating unit and the pressurizing unit in a standby state after the job ends.   3. The fixing device according to claim 1, wherein the contact / separation mechanism separates the heating unit and the pressurizing unit in an off mode in a state where power supply to the heating element is cut off. Provided with temperature detecting means for detecting the temperature of the pressurizing part,
The fixing device according to claim 1, wherein the contact / separation mechanism separates the heating unit and the pressing unit when the temperature of the pressing unit becomes equal to or lower than a specified temperature.   The said contact / separation mechanism separates the said heating part and a pressurization part, when the electric energy stored in the said auxiliary power supply device is below a regulation value, The one of Claims 1 thru | or 4 characterized by the above-mentioned. Fixing device. An image forming apparatus comprising the fixing device according to claim 1.