JP5453784B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to the efficiency of heating of a fixing member of a fixing device in an image forming apparatus including a fixing device and a power storage device, for example, a fixing device of an image forming apparatus such as a copying machine, a printer device, and a facsimile device using an electrophotographic system. It relates to the efficiency of heating in

  In recent years, environmental problems have become important and image forming apparatuses such as copiers and printers have been saving power. In order to save power in the image forming apparatus, it is effective to lower the temperature of a heating unit such as a fixing roller and a fixing belt of the fixing device when the image forming apparatus is not passing paper (for example, during standby). However, if the temperature of the heating unit during non-sheet passing is lowered, when the fixing device is used, the temperature of the heating unit must be raised to a fixed temperature at which fixing can be performed again. Have to wait. As a result, it takes time until the image forming apparatus is ready for use, and the usability of the image forming apparatus deteriorates.

In order to avoid this, there are the following two measures.
(1) By assisting the power supply to the heating element of the heating unit by supplying power from the auxiliary power supply (also referred to as a power storage device or a capacitor) to the heating element of the heating unit (also referred to as a heating means or a capacitor heater) The temperature raising time of the heating unit can be shortened (see, for example, Patent Documents 1 and 2). By using this auxiliary power supply device to assist the power supply to the heating element of the heating unit not only when the heating unit is heated (when starting up or when returning from the off mode) but also when passing paper, power can be used more effectively. .
(2) The thickness of the fixing roller is reduced as a configuration for quickly increasing the temperature of the fixing member (fixing roller).

The “off mode” is a state in which power supply to the heating element is stopped until the following operation (a) or (b) is performed (heat generation in preparation for returning to the next fixable state). State in which power supply to the body is stopped).
(a) A user presses a power switch (not a main power switch) on the image forming apparatus main body to turn it on.
(b) An external signal such as an image formation start signal is input.

However, such a workaround also has the following problems.
(I) While power is being supplied from the auxiliary power supply device (capacitor) to the heating element (capacitor heater), when the charging power of the capacitor is lost, the capacitor heater does not generate heat and the capacitor heater becomes an obstacle. As a result, the heat transfer efficiency in the fixing roller decreases.
(Ii) If the thickness of the fixing roller is reduced, the temperature drop of the fixing roller during paper feeding increases. In particular, the temperature drop at the end of the fixing roller is large.

  According to the above (i) and (ii), in a so-called high-speed machine that forms an image at high speed, when the power supplied to the heater inside the fixing roller is insufficient, the temperature reaches the lower limit temperature that can be fixed immediately, and good fixing is achieved. In order to ensure the processing, the image forming speed (sheet conveying speed) is slowed down, or a waiting time until the fixing roller temperature rises is set, so the number of sheets passed (CPM) per minute is reduced.

  There has been proposed a technique for solving this problem by detecting the power of the auxiliary power supply (capacitor) and controlling the rotation of the fixing member based on the detection result (for example, Patent Document 3). reference.). However, even with this technique, there are cases where it is difficult to solve the problem.

JP 2005-250464 A JP 2005-221696 A JP 2005-17564 A

  The present invention has been made in view of the above-described problems in the prior art, and even when there is no discharge power of the power storage device during the image forming process on the sheet, the number of sheets passed (CPM) per minute is high. An object of the present invention is to provide an image forming apparatus capable of preventing a temperature drop of a fixing member while maintaining a level.

The present invention provided to solve the above problems is as follows.
[1] A power storage device, a rotating fixing member, a pressure member that forms a nip portion in contact with the fixing member, a first heating unit that heats the fixing member by supplying power from an external power source, and the power storage A second heating unit that heats the fixing member by power supply from the apparatus; and a charging device that receives power supply from the external power source and charges the power storage device. When the discharge voltage of the apparatus becomes equal to or lower than a predetermined voltage, image formation is performed by stopping the discharge of the power storage device and directly supplying power for slightly lighting the second heating means from the charging device to the second heating means apparatus.
[2] When the discharge voltage of the power storage device becomes a predetermined voltage or less in the image forming process step on the sheet, it occurs due to at least one of the peripheral device pause, the peripheral device not connected, and the input voltage change of the external power supply The image forming apparatus according to [1], wherein the surplus power of the image forming apparatus is used to directly supply power for slightly lighting the second heating unit from the charging device to the second heating unit.
[3] The first heating unit includes an end heating unit that heats an end of the fixing member by supplying power from an external power source, and the fixing member is set to a predetermined temperature or less after the image forming process on the sheet is started. The surplus power of the image forming apparatus, which is generated by at least one of suspension of the peripheral device, disconnection of the peripheral device, and change in the input voltage of the external power supply, is supplied to the end heating unit. Image forming apparatus.
[4] The first heating unit includes an end heating unit that heats an end of the fixing member by supplying power from an external power source, and discharge voltage of the power storage device in an image forming process for a small-sized sheet. When the voltage becomes equal to or lower than a predetermined voltage, when the fixing member is at a predetermined temperature or higher, the power to be supplied to the end heating means is used to directly supply power from the charging device to the second heating means. 1].
[5] When the discharge voltage of the power storage device is equal to or lower than a predetermined voltage in the image forming process step on the sheet, the power to be supplied to the first heating unit is used when the fixing member is higher than the predetermined temperature. The image forming apparatus according to [1], wherein power is directly supplied from the charging device to the second heating unit.
[6] The image forming apparatus according to [1], wherein the predetermined voltage is a dischargeable voltage of the power storage device .

According to the image forming apparatus of the present invention, when the discharge voltage of the power storage device becomes equal to or lower than a predetermined voltage in the image forming process step on the sheet, the discharge of the power storage device is stopped and the second heating is performed from the charging device. Since the electric power is directly supplied to the means, the temperature of the fixing member is maintained while maintaining a high level of the number of sheets passed (CPM) per minute even when the discharge power of the power storage device runs out during the image forming process on the sheet. Can be prevented.
Further, according to the image forming apparatus of the present invention, when the discharge voltage of the power storage device becomes a predetermined voltage or less in the image forming process step on the sheet, the power storage device receives power supply from the charging device. Since the electric power is supplied to the second heating means while being charged, even if the discharge voltage of the power storage device once falls below a predetermined voltage during the image forming process on the sheet, It is possible to prevent a decrease in the temperature of the fixing member while maintaining a high level of the number of sheets passed (CPM).

The configuration of the image forming apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration example of an image forming apparatus according to the present invention. Here, an image forming apparatus such as an electrophotographic copying machine or a printer is conceptually shown as an example.
The image forming apparatus of the present invention is capable of, for example, continuously passing 100 sheets (75 CPM (CPM: copy speed)), and mainly includes a reading unit 11 for reading a document, and an image for forming an image. A forming unit 12, an automatic document feeder (ADF) 13, a document discharge tray 14 for stacking documents sent from the ADF 13, a sheet feeding unit 19 including sheet cassettes 15 to 18, and a sheet discharge for stacking recording sheets (sheets). Section (discharge tray 20). For example, the ADF 13 has a maximum stacking number of 100 sheets, and the reading unit 11 sets the reading time of 100 originals to 60 seconds. Then, when the document D is set on the document table 21 of the ADF 13 and an operation on an operation unit (not shown), for example, a press operation of a print key is performed, the uppermost document D is sent out in the direction of the arrow B1 by the rotation of the pickup roller 22 Then, by the rotation of the document conveying belt 23, the paper is fed onto the contact glass 24 fixed to the image reading unit 11, and stops there. The image of the document D placed on the contact glass 24 is read by a reading device 25 located between the image forming unit 12 and the contact glass 24. The reading device 25 includes a light source 26 that illuminates the document D on the contact glass 24, an optical system 27 that forms an image of the document, a photoelectric conversion element 28 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 transport belt 23 and discharged onto the paper discharge tray 14. In this way, the document D is fed one by one onto the contact glass 24 and the document image is read by the image reading unit 1.

  On the other hand, inside the image forming unit 12, a photoconductor 30 as an image carrier is disposed. The photosensitive member 30 is driven to rotate clockwise in the drawing, and the surface is charged to a predetermined potential by the charging device 31. Further, the writing unit 32 emits a laser beam L that is light-modulated in accordance with image information read by the reading device 25, and the surface of the charged photoreceptor 30 is exposed with the laser beam L, whereby the photoreceptor is exposed. An electrostatic latent image is formed on the surface 30. When the electrostatic latent image passes through the developing device 33, the electrostatic latent image is transferred to the sheet P fed between the photosensitive member 30 and the transfer device 34 by the opposing transfer device 34. The surface of the photoconductor 30 after the toner image is transferred is cleaned by a cleaning device 35.

  A plurality of paper feed cassettes 15 to 18 arranged at the lower part of the image forming unit 12 contain sheets P that are recording media such as paper, and the sheet P is transferred from any of the paper feed cassettes 15 to 18 by an arrow B3. The toner image formed on the surface of the photoreceptor 30 as described above is transferred onto the surface of the sheet P. Next, the sheet P is passed through the fixing device 36 in the image forming unit 12 as indicated by an arrow B4, and the toner image transferred to the surface of the sheet P by the action of heat and pressure is fixed. The sheet P that has passed through the fixing device 36 is conveyed by the discharge roller pair 37, discharged to the discharge tray 20 as indicated by an arrow B5, and stacked.

  Note that the image forming apparatus has a main power supply, and supplies power to various units of each part of the image forming apparatus with power from an external power supply. Specifically, the main power supply device supplies power from the commercial power supply to various units by inserting and connecting a plug of a power supply line to a commercial power outlet (for example, 100V, 15A) as an external power supply.

FIG. 2 is a schematic diagram illustrating an example of a fixing device 36 that heats and pressurizes the toner image transferred to the sheet P and fixes the toner image to the sheet.
As shown in FIG. 2, the fixing device 36 includes a fixing member 3 that is a cylindrical rotating body that is rotatably supported by an axis (an axis in a direction perpendicular to the paper surface of FIG. 2A) and a pressure member. The member 4 is included. For example, the fixing member 3 includes a fixing roller (hereinafter referred to as a fixing roller 3) as a heating unit, and the pressure member 4 includes, for example, a pressure member (hereinafter referred to as a pressure roller 4). A heating element 2 for generating heat and heating the fixing roller 3 is disposed in the fixing roller 3. Outside the fixing roller 3, a temperature detecting means 8 a for detecting the surface temperature of the central portion of the fixing roller 3 and an end portion of the heating roller 2 are disposed. Temperature detecting means 8b for detecting the surface temperature is arranged. Further, outside the pressure roller 4, a temperature detection means 8c such as a thermistor for detecting the surface temperature of the pressure roller 4 is disposed. Hereinafter, the temperature detection means 8a, 8b, and 8c are collectively referred to as temperature detection means (temperature sensor) 8.

As shown in FIG. 2, the heating element 2 includes a main heating element (also referred to as a first heating means or a main heating heater) 2a composed of an AC heater, and an auxiliary heating element 2b (a second heating means, a capacitor heater, an auxiliary heater) composed of a DC heater. For example, a halogen heater is used. The main heating heater 2a is mainly composed of a main heating heater 2a1 (also referred to as a central heating means or a central heating heater) that heats a central portion in the width direction of the fixing roller 3 and a main heat generation that heats an end portion of the fixing roller 3. The heater 2a2 (also referred to as an end heating means or an end heater).
However, the auxiliary heater 2b may have a heat generation distribution adjusted in the width direction of the fixing roller 3 (light distribution adjusted). For example, a heater whose light distribution is adjusted so that the heat generation distribution at the center portion of the fixing roller 3 is larger than the end portion, or a heater whose light distribution is adjusted so that the heat generation distribution at the end portion of the fixing roller 3 is larger than the center portion. But you can.

  The sum of the rated power of the central heater 2a1, the fixing power of the end heater 2a2, and the rated power of the auxiliary heater 2b is 80% or more of the maximum power consumption of the AC power source consumed by the image forming apparatus. It is preferable to use a heater with a rated power. In the case of power from an external power source (commercial power source) (in the case of Japan, 1500 V of 100V15A), the maximum power consumption of the AC power source consumed by the image forming apparatus is 1500 W, so the total rated power of each heater is 1200 W or more. . Also, the rated power is such that the sum of the rated power of the central heater 2a1, the fixing power of the end heater 2a2, and the rated power of the auxiliary heater 2b is equal to or greater than the maximum power consumption of the AC power source consumed by the image forming apparatus. It is preferable to use a heater. In this case, the total rated power of each heater is 1500 W or more.

  The roller base of the fixing roller 3 is preferably made of a metal such as aluminum or iron from the viewpoint of durability, deformation due to pressure, or the like. The thickness of the roller base at this time is thin so that the fixing roller 3 is rapidly heated when the apparatus is started up and reaches a predetermined temperature in a short time, and is preferably less than 5 mm, preferably 1 mm or less. More preferred. For example, in a 75 CPM machine used for preventing the temperature of the fixing roller from being lowered during paper feeding, the fixing roller 3 uses an aluminum roller base having an outer diameter of φ40 mm and a wall thickness of t0.7 mm. This is because the thickness is such that the temperature can be raised to a fixable state within 30 seconds, and even the load necessary to form the nip width necessary for fixing is not destroyed. In the 75 CPM machine, a thick roller of about 5.0 to 10 mm has been used when an auxiliary power source is not used. However, a combination of a thin roller and heating by an auxiliary power source can significantly reduce the startup time. It has become. Further, it is desirable to form a release layer such as PFA or PTFE for preventing the toner from adhering to the surface of the fixing roller 3. On the inner surface of the fixing roller 3, the radiation of the heating element 2, which is a halogen heater, is formed. It is desirable to perform a blackening treatment for efficiently absorbing heat.

  The pressure roller 4 is formed by forming an elastic layer such as rubber on a core metal, and has a larger heat capacity than the fixing roller 3. The pressure roller 4 is brought into pressure contact with the fixing roller 3 to form a nip portion, and a recording material P such as paper on which an unfixed image is formed is passed through the nip portion, whereby a toner image is recorded by heat and pressure. Fix on P. Further, a nip portion may be formed between the pressure roller 4 and the fixing roller 3 by using a pressure roller having a foam layer as the pressure roller 4.

FIG. 3 is a circuit diagram showing a configuration of an embodiment of a heating device provided in the fixing device 36.
The heating device of the present embodiment includes a heating unit 10, a main power supply device 50, an auxiliary power supply device (also referred to as a power storage device) 7, a power storage detector 7v connected to the auxiliary power supply device 7, and a charging device (also referred to as a charger) 1a. Furthermore, the controller 5a and the triac 5b related to the power supply control of the main power supply device 50, the controller 6a and the FET 6b related to the power supply control of the auxiliary power supply device 7, the changeover switches 9a and 9b, and the control means 1 are provided.

  The heating unit 10 includes a main heating element 2a that generates heat by the electric power supplied from the main power supply device 50, and an auxiliary heating element 2b that generates heat by the electric power supplied from the auxiliary power supply apparatus 7, and is a fixing roller that is a heated object. 3 is heated. Although not shown in detail, the main power supply device 50 is supplied with power from a commercial power supply in the image forming apparatus provided with the heating device. The main power supply device 50 has a function of adjusting, for example, power supplied from an outlet or the like to a voltage corresponding to the heating unit 10. However, since it is well-known, detailed illustration and description thereof are omitted.

  The auxiliary power supply device 7 has a chargeable / dischargeable capacitor. As the capacitor, for example, a module having a module configuration in which 15 to 40 cells having a rated voltage of 2.5 V and a capacitance of about 400 to 1000 F are connected in series to obtain a predetermined rated voltage and capacity is desirable. Further, for use in preventing a decrease in the fixing temperature during continuous paper feeding, for example, a heater having a rating of about 300 to 600 w, in which 18 to 22 cells of 500 to 700 F are connected in series, is suitable. This has sufficient capacity for power supply for about 1 to 2 minutes, and when all the stored power is supplied from a high temperature state due to a runaway control system, the power decreases as the voltage decreases, reducing the risk of ignition. This is because the capacity can be reduced. Another reason is that the voltage is about 50V and the risk of electric shock is low.

  Further, as an application for supplying power at start-up, for example, a heater having a rating of 800 to 1000 w is connected in parallel to the auxiliary power supply device to supply a total power of about 1600 to 2000 w. They may be connected in series. This is equipped with a capacity and voltage for supplying sufficient power for power supply for about 10 seconds, and a capacity capable of preventing a decrease in fixing temperature by using only one heater even when shifting during continuous paper feeding. It is for having.

  In the actual operation state, a voltage lower than the rated voltage is set as the charging target voltage because the reliability can be improved in consideration of variations in the voltage circuit and the durability of the capacitor cell. Also, a module configuration in which cells with lower capacitances of about 100 F are connected in parallel may be used. However, the number of electronic circuits required per cell can be reduced, and it is easy to detect when a failure occurs in the cell. It is desirable to connect the cells in series. The reason why the above configuration is adopted is that, unlike a secondary battery, a capacitor such as an electric double layer capacitor has excellent characteristics because it does not involve a chemical reaction.

  In the auxiliary power supply device using a general nickel-cadmium battery as a secondary battery, it takes a long time of several tens of minutes to several hours even if rapid charging is performed, but in the auxiliary power supply device 7 using a capacitor, it takes about several minutes. When the standby state and the heating state are repeated within the same time, by using the auxiliary power supply device 7 using a capacitor, it is possible to reliably supply power from the auxiliary power supply device 7 at the start of heating. The heating unit 10 can be raised to a predetermined temperature in a short time. In addition, since the nickel-cadmium battery has an allowable number of repetitions of charge / discharge of about 500 to 1000 times, it has a short life as an auxiliary power source for heating, and the trouble and cost of replacement are problematic. Auxiliary power supply device 7 using a battery has an allowable number of repetitions of charge and discharge of several million times or more, and is less susceptible to deterioration due to repeated charge and discharge, and also does not require liquid replacement or replenishment unlike lead-acid batteries. It requires little maintenance and can be used stably for a long time.

  In addition, the electric double layer capacitor has no dielectric and uses the adsorption / desorption reaction (charging / discharging) of the ion adsorbing layer of the electric double layer in which charges of ions or solvent molecules concentrated at the solid electrode and solution interface are concentrated. It is strong against repeated charging / discharging, has a long life, does not require maintenance, is environmentally friendly, has a shorter charging time than other types of batteries, has higher charging / discharging efficiency, and has a remaining power due to voltage detection. Recently, a large-capacity product having excellent features such as easy-to-understand and having a capacitance of several tens of thousands F and an energy density of several tens of wh / kg has been developed, and the capacity has been further increased.

  FIG. 4 shows discharge characteristics when an electric double layer capacitor (hereinafter referred to as a capacitor), which is the auxiliary power supply device 7, is connected to the auxiliary heating element 2b. The vertical axis V in FIG. 4 indicates the voltage of the capacitor (residual voltage), and the horizontal axis indicates the discharge time. Due to the characteristics of the capacitor, the voltage is high at the beginning of discharge, and the voltage decreases with the discharge time. In other words, the capacitor can supply a large amount of power at the beginning of discharge, but has a characteristic that the supply power decreases at the end of discharge. The discharge stop voltage V3 is a voltage at which the remaining amount of electricity in the capacitor almost disappears during the discharge process and hardly discharges, and is a voltage at which the discharge as the auxiliary power supply device 7 is stopped. The dischargeable voltage V2 is a boundary voltage between a voltage having a power for heating the fixing roller 3 and a voltage not having a power until the fixing roller 3 is heated at the start of discharging, and is equal to or higher than the dischargeable voltage V2. If it is less, the voltage starts discharging, and if it is less, the voltage does not discharge.

  The main switch (not shown in FIG. 3) turns on / off the power supplied from the main power supply 50 to the main heating element 2a, and the charger 1a uses the power supplied from the main power supply 50 for the auxiliary power supply. 7 capacitor is charged. The change-over switches 9a and 9b are for switching between charging of the auxiliary power supply device 7 and power supply from the auxiliary power supply device 7 to the auxiliary heating element 2b.

  The control means 1 has a CPU and performs control to turn on / off the power supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b under preset conditions described later. However, the configuration of the control means 1 shown in the figure is merely an example showing only a portion that controls the heating unit 10, and various configurations such as a device that controls the entire image forming apparatus can be employed. Further, the connection form for controlling the auxiliary power supply 7 is not limited to the illustrated example. For example, various forms such as a configuration in which the changeover switches 9a and 9b are switched to perform on / off control and the like can be employed.

Next, the basic operation of the heating device will be described with reference to FIGS.
First, at the time of standby, the selector switches 9a and 9b are switched to connect the charger 1a to the auxiliary power supply device 7 to charge the capacitor of the auxiliary power supply device 7. When the fixing roller 3 is heated by the heating device in this state (when the device is started up), the triac 5b is turned on to supply power from the main power supply device 50 to the main heating element 2a, and at the same time, the changeover switches 9a and 9b are switched. Then, electric power is supplied from the auxiliary power supply 7 to the auxiliary heating element 2b, and a large amount of electric power is supplied to the heating unit 10. Thus, when heating of the fixing roller 3 by the heating unit 10 is started, a large amount of power is supplied from both the main power supply device 50 and the auxiliary power supply device 7 to the heating unit 10, so that the heating unit 10 is turned on for a short time. Can be raised to a predetermined temperature.

  Further, when a predetermined time elapses after the auxiliary power supply 7 supplies electric power to the auxiliary heating element 2b of the heating unit 10 and starts heating, the control means 1 receives the auxiliary heat generation from the auxiliary power supply 7. The electric power supplied to the body 2b is cut off to prevent overheating of the heating unit 10 and maintained at a predetermined temperature. The power supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b decreases as time elapses after the supply is started. A time for cutting off the power supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b is determined according to the reduction amount of the supplied power, and when the supply power is reduced to some extent, the auxiliary power supply device 7 transfers to the auxiliary heating element 2b. When the supplied power is cut off, it is possible to prevent deterioration of each component of the surrounding circuit and electromagnetic noise that occur when cutting off in the state of supplying a large amount of power.

  In the image forming processing step of forming an image on the sheet according to the input job, the sheet P to which the toner image T sent to the fixing device (FIG. 2) is transferred is between the fixing roller 3 and the pressure roller 4. Then, the toner T is heated and melted by the fixing roller 3 which is conveyed to the nip portion and heated to a constant temperature by the heating unit 10 and fixed on the sheet P as a toner image. Therefore, power is supplied from the main power supply 50 and the auxiliary power supply 7 to the main heating element 2a and the auxiliary heating element 2b of the heating unit 10 of the fixing roller 3, thereby increasing the temperature of the fixing roller 3 and the auxiliary power supply. By controlling on / off the power supplied from the apparatus 7, the temperature of the fixing roller 3 is prevented from becoming too high, and the fixing temperature is kept at a constant temperature or a desired temperature, or a required temperature change is shown. Thus, the toner T is stably heated and melted, and a good quality toner image T is fixed on the sheet P. In addition, since the power is supplied from the main power supply device 50 and the auxiliary power supply device 7 to the main heating element 2a and the auxiliary heating element 2b of the heating unit 10 built in the fixing roller 3, the temperature of the fixing roller 3 is raised. The surface temperature of the toner can be quickly raised to a predetermined fixing temperature.

  Here, a heating control process of the fixing device in the conventional image forming apparatus will be described with reference to FIG. 5 shows the temperature of the fixing roller 3 during operation of the image forming apparatus configured as shown in FIGS. 1 to 3 (FIG. 5A), the power supplied to the heating unit 10 (FIG. 5B), It is a figure which shows the change of the discharge power (FIG.5 (c)) of the power supply device 50, and the residual voltage (FIG.5 (d)) of the auxiliary power supply device 7. FIG.

  The temperature of the fixing roller 3 rises with the start of the start-up operation by the continuous copy command (time point a) from the state where not much power is consumed during standby, and moves to the sheet P by the start of the sheet passing operation (time point b). As a result, the temperature decreases, and then the temperature rises slightly until the end of document reading (time point c) and the end of copying (time point d), and the temperature decreases when returning to the standby operation. In addition, between the time points a and b is, for example, 30 seconds, between the time points b and c, for example, 60 seconds, and between the time points b and d, for example, 80 seconds.

  The power supplied to the heating unit 10 during this operation is from a power non-supply state (up to time point a) during standby, power supply by the main power supply device 50 (between time points a and b), and paper feeding operation during startup. Power supply by the main power supply device 50 and the auxiliary power supply device 7 (between time points b and c), power supply by the main power supply device 50 (between time points c and d) after completion of document reading, and a non-supply state during standby Return (after time d) changes.

  The power supply (between time points b and c) by the main power supply device 50 and the auxiliary power supply device 7 is a capacitor of the auxiliary power supply device 7 in order to prevent the power supply during continuous sheet feeding from being insufficient and the temperature of the fixing roller 3 from decreasing. Is used to prevent a reduction in productivity such as a decrease in copy speed (CPM down) or stop until the temperature of the fixing roller 3 recovers during continuous paper feeding.

  Correspondingly, the power supply by the main power supply device 50 is the normal power of the commercial power supply whose power consumption is the upper limit value when image formation is started from the non-supply state in the standby state (for example, if the rated power is 1200 W, the value or (Neighbor value thereof) (between time points a and b), and power is distributed to the image reading and other driving units, so that the power of the fixing device 36 is reduced (for example, decreased to 800 W: between time points b and c), and image reading is completed. Changes to power recovery (for example, recovery up to 900 W: between time points c and d), and after the completion of copying, charging power for charging the capacitor is supplied up to time point e, and then returns to a standby state (non-supply state).

  Further, the output voltage of the capacitor of the auxiliary power supply device 7 shows the target value 44V which is the maximum value during standby, and decreases by supplying power for heating the fixing roller 3 during the sheet passing operation (time points b and c). When the charge voltage of the auxiliary power supply 7 is lost (when the discharge stop voltage V3 is reached (time point c)), the discharge of the auxiliary power supply device 7 is stopped and the auxiliary heating element 2b does not generate heat (time point c). , D). Then, after the copy is completed, the auxiliary power supply 7 is charged from the main power supply 50, the remaining power increases, reaches the target voltage at the time point e, and returns to the standby state.

Such conventional heating control shows a state in which the temperature of the fixing roller 3 is maintained at a problem-free temperature between time points c and d in FIG. 5A, but the auxiliary heating element 2b generates heat. Therefore, there is a possibility that the auxiliary heating element 2b itself becomes an obstacle to the radiant heat transfer to the fixing roller 3 and lowers the electrothermal efficiency, causing a temperature drop of the fixing roller 3 and causing a problem of CPM down. It was.
The inventor has intensively studied that surplus power exists in the image forming apparatus in such a heating control process, and has achieved the present invention. Hereinafter, the configuration of the main part of the present invention will be described.

First, a first embodiment of an image forming apparatus according to the present invention will be described.
As shown in FIGS. 1 to 3, the image forming apparatus according to the present invention has a power storage device (auxiliary power supply device 7), a rotating fixing member (fixing roller 3), and a nip portion in contact with the fixing member. A pressure member to be formed (pressure roller 4), a first heating means (main heating element 2a) for heating the fixing member by power supply from an external power source (main power supply device 50), and power supply from the power storage device A fixing device (fixing device 36) having a second heating means (auxiliary heating element 2b) that heats the fixing member by a charging device, and a charging device (charging device 1a) that charges the power storage device. When the discharge voltage of the power storage device becomes equal to or lower than a predetermined voltage in the image formation processing step, the discharge of the power storage device is stopped and power is directly supplied from the charging device to the second heating means.

A heating control process of the fixing device in the image forming apparatus of this embodiment will be described with reference to FIG.
6 shows the temperature of the fixing roller 3 during operation of the image forming apparatus of the present invention configured as shown in FIGS. 1 to 3 (FIG. 6A) and the power supplied to the heating unit 10 (FIG. 6B). FIG. 6 is a diagram showing changes in the discharged power of the main power supply device 50 (FIG. 6C) and the residual voltage of the auxiliary power supply device 7 (FIG. 6D). In this example, 100 continuous originals (75 CPM), ADF maximum stacking number 100 sheets, capacitor rated voltage 45 V as auxiliary power supply device 7, charging target value 44 V (V1, not fully charged to prevent deterioration) The discharge start permission range from the capacitor is 30 to 44 V, and the discharge end value is 20 V (the discharge time from the target voltage 44 V to the end value 20 V is 60 seconds, for example). When the voltage of the capacitor is less than 20V, the auxiliary heating element 2b of the heating unit 10 hardly generates heat, so the voltage 20V is set as the end threshold value (discharge stop voltage V ₃ ). Further, a dischargeable voltage _{V 2} to 25V.

  The temperature of the fixing roller 3 rises with the start of the start-up operation by the continuous copy command (time point a) from the state where not much power is consumed during standby, and moves to the sheet P by the start of the sheet passing operation (time point b). As a result, the temperature decreases, and then the temperature rises slightly until the end of document reading (time point c) and the end of copying (time point d), and the temperature decreases when returning to the standby operation. In addition, between the time points a and b is, for example, 30 seconds, between the time points b and c, for example, 60 seconds, and between the time points b and d, for example, 80 seconds.

  The power supplied to the heating unit 10 during this operation is from a power non-supply state (up to time point a) during standby, power supply by the main power supply device 50 (between time points a and b), and paper feeding operation during startup. Power supply by the main power supply device 50 and the auxiliary power supply device 7 (between time points b and c ′), power supply by the main power supply device 50 after the document reading is finished (between time points c and d), and a non-supply state during standby Change (after time d). Details are as follows.

(1) Until time point a In the heating device of FIG. 3, both the triac 5b and the FET 6b are off, and the heating element 2 is not supplied with power. At this time, since the remaining power amount of the capacitor of the auxiliary power supply device 7 is in a standby state, the target value 44V (charging voltage V1) which is the maximum value is indicated.

(2) Between time points a and b In the heating device of FIG. 3, the triac 5b is turned on while the FET 6b is off, the heating power is supplied from the main power supply device 50 to the main heating element 2a, and the fixing roller 3 is kept at a predetermined temperature. The main heating element 2a is heated until it becomes. The power supply by the main power supply 50 increases from the non-supply state during standby to the normal power of the commercial power supply, which is the upper limit value (for example, the value of the rated power supply is 1200 W or the vicinity thereof) with the start of image formation. To do.

(3) Between time points b and c ′ As in the heating device of FIG. 3, both the triac 5b and the FET 6b are turned on, and at the same time, the changeover switches 9a and 9b are both on the contact (1) side. As a result, heating power is supplied from the main power supply device 50 to the main heating element 2a through the path indicated by a thick line in FIG. 3, and power from the capacitor discharge is supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b. Here, the power supply by the main power supply device 50 distributes the power to the image reading and other driving units, so that the power to the fixing device 36 is reduced more than between the time points a and b (for example, decreased to 800 W). To do). On the other hand, the power supply by the auxiliary power supply device 17 is a capacitor of the auxiliary power supply device 7 in order to prevent the temperature of the fixing roller 3 from being lowered due to a shortage of power supply during continuous paper feeding due to a decrease in power supply from the main power supply device 50. Is used to prevent a reduction in productivity such as a decrease in copy speed (CPM down) or stop until the temperature of the fixing roller 3 recovers during continuous paper feeding. At this time, the remaining power amount of the auxiliary power supply device 7 gradually decreases until the dischargeable voltage V2 is reached.

(4) Between time points c ′ and d As in the heating device of FIG. 7A, both the triac 5b and the FET 6b are turned on, and at the same time, the changeover switch 9a is on the contact (1) side and the changeover switch 9b is on the contact (2) side. It becomes. Thereby, the heating power is supplied from the main power supply device 50 to the main heating element 2a through the path indicated by the thick line in FIG. Further, discharging of the capacitor of the auxiliary power supply device 7 is stopped, and power is directly supplied from the charging device 1a to the auxiliary heating element 2b using the power of the main power supply device 50. The voltage from the charging device 1a at this time is a dischargeable voltage V2, and the auxiliary heating element 2b is supplied with electric power E1 for lighting the auxiliary heating element 2b even slightly. As the power supplied to the auxiliary heating element 2b at this time, it is preferable to use surplus power as an image forming apparatus as will be described later. As a result, the auxiliary heating element 2b is turned on slightly, so that the auxiliary heating element 2b, which does not generate heat due to the loss of the charging voltage of the auxiliary power supply device 7 as in the prior art, does not become an obstacle to heating the fixing roller 3. A decrease in electrothermal efficiency can be prevented. Further, since the remaining power amount of the capacitor of the auxiliary power supply device 7 is held at the dischargeable voltage V2, it is possible to charge to the charging voltage V1 promptly and correspond to the next job.

(5) Between time points d and e As in the heating device in FIG. 7B, both the triac 5b and the FET 6b are turned off, and the change-over switches 9a and 9b are both on the contact (2) side. As a result, power supply to the heating unit 10 (heating element 2) is stopped, and power is supplied from the main power supply device 50 to the capacitor of the auxiliary power supply device 7 through the charging device 1a along the path indicated by a thick line in FIG. 7B. Is supplied and charging is performed. Then, when the remaining power amount of the auxiliary power supply device 7 reaches the charging voltage V1, the charging from the charging device 1a is stopped and enters a standby state.

Regarding the power supply control to the auxiliary heating element (capacitor heater) 2b between the time points b and d, the control flow shown in FIG.
(S11) When the paper feeding is started, it is confirmed whether or not the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S12) When the remaining power amount X is not larger than V2 (when X ≦ V2), the state of the heating device shown in FIG. 7A is established, and power is directly supplied from the charging device 1a to the auxiliary heating element 2b. Continue until the end of the paper.
(S13) When the remaining power amount X is larger than V2 (when X> V2), the state of the heating device shown in FIG. 3 is established, and discharge power is supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b.
(S14) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S15) When the power storage detector 7v detects X = V2, the changeover switch 9b is switched to the state of the heating device shown in FIG. 7A, and power is directly supplied to the auxiliary heating element 2b from the charging device 1a. This is continued until the end of paper passing.

  When the discharge voltage of the power storage device (auxiliary power supply device 7) becomes a predetermined voltage (for example, dischargeable voltage V2) or less in the image forming process step on the sheet, the surplus power of the image forming device is used. The electric power may be supplied directly from the charging device (charging device 1a) to the second heating means (auxiliary heating element 2b).

  Further, the surplus power of the image forming apparatus used at this time is surplus power generated by any of the following: the peripheral device of the image forming apparatus is stopped, the peripheral device is not connected to the image forming apparatus, or the input voltage of the external power supply is changed. Preferably there is.

  At this time, in order to use the surplus power of the image forming apparatus, it is necessary to detect cases of the peripheral device of the image forming apparatus being stopped, the peripheral device not being connected to the image forming apparatus, and the input voltage change of the external power source. is there. The configuration is shown in FIG.

  FIG. 9 is a block diagram illustrating a functional configuration of a main part of the heating device of the fixing device 36 according to the present embodiment. The control means (CPU) 1 includes ON / OFF information from the power-on switch or copy start button Csw that instructs the rise of the image forming apparatus (FIG. 1) of the present invention, residual voltage information from the power storage detector 7v, and input voltage. Input voltage value information of the external power source from the detection unit 40, connection peripheral device (peripheral device) information of the image forming apparatus from the peripheral device detection unit 41, operation information of the scanner and the like from the internal operation confirmation unit 42, and temperature detection means ( The temperature information of the fixing roller 3 from the temperature sensor 8 is connected so as to be taken into the internal information identification unit Dd, and the internal control execution unit Ca is operated to charge / discharge the capacitor of the auxiliary power supply device 7. The charge / discharge control part 1A to be controlled is functionally configured.

When the surplus power generated by the suspension of the peripheral device of the image forming apparatus is used, the power supply control to the auxiliary heating element 2b between the time points b and d is performed according to the control flow shown in FIG. .
(S21) When paper feeding is started, the operation status of the peripheral device such as a scanner is confirmed by the internal operation confirmation unit 42, the operation information is sent to the information identification unit Dd, and the control means 1 is based on the operation information. The surplus power generated by the suspension of the peripheral device of the image forming apparatus is confirmed. Here, the surplus power generated by the suspension of the peripheral device of the image forming apparatus is a surplus power due to the operating state of a motor or the like that is not operating when the image forming apparatus main body is operating (at the time of paper passing). For example, in the image forming apparatus shown in FIG. 1, when the automatic document feeder (ADF) 13 is not used at the time of paper passing, or when 100 originals set on the document table are copied, the reading unit 11 is used. This is the surplus power generated when no operation is performed after reading once, or when the one-sided copy is selected in the automatic document feeder (ADF) 13 having the double-sided simultaneous reading function and the back side is not read.
(S22) It is confirmed whether or not the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S23) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. Electric power is directly supplied from the charging device 1a using the confirmed surplus electric power, and is continued until the end of paper feeding.
(S24) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S25) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S26) When the power storage detector 7v detects X = V2, the changeover switch 9b is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. Electric power is directly supplied from the charging device 1a using the surplus power confirmed in S21, and is continued until the end of paper feeding.

  As described above, since the electric power is surplus depending on the operating state of the motor or the like that is not operating when the image forming apparatus main body is operating (when the paper is passed), the electric power is turned to the capacitor charging power of the auxiliary power supply device 7.

Further, when surplus power generated due to the disconnection of the peripheral device to the image forming apparatus is used, power supply to the auxiliary heating element 2b between time points b and d according to the control flow shown in FIG. 11 on the assumption of the configuration of FIG. Control is performed.
(S31) When the sheet is started, the peripheral device connected to the image forming apparatus is confirmed by the peripheral device detection unit 41, and information on the connected peripheral device (peripheral device) is sent to the information identification unit Dd for control. The means 1 confirms the surplus power generated due to the unconnected peripheral device to the image forming apparatus based on the information. Here, as the surplus power generated when the peripheral device is not connected to the image forming apparatus, a peripheral device (for example, a finisher, a large-capacity paper feed tray, a cover feeder, or the like) is connected in various options in the image forming apparatus main body. The power supply from the external power supply is allocated so that it can be used in the future, but in actual use, it is rare to have a full system that connects all peripheral devices, and it is not connected at that time This corresponds to the amount of power assumed by the peripheral device. For example, when the peripheral device is detected and not connected, the surplus power is calculated according to a preset table. If there are several types of finishers depending on the specifications, a table is provided accordingly.
(S32) It is confirmed whether the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S33) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 7A, and the auxiliary heating element 2b is in the above-described step S31. Electric power is directly supplied from the charging device 1a using the confirmed surplus electric power, and is continued until the end of paper feeding.
(S34) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S35) After that, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S36) When the power storage detector 7v detects X = V2, the changeover switch 9b is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. Power is directly supplied from the charging device 1a using the surplus power confirmed in S31, and is continued until the end of paper feeding.

When surplus power generated by the change in the input voltage of the external power supply is used, the power supply control to the auxiliary heating element 2b between the time points b and d is performed according to the control flow shown in FIG. 12 on the premise of the configuration of FIG. .
(S41) When the paper feeding is started, the input voltage value of the external power source is confirmed by the input voltage detection unit 40, and the input voltage value information is sent to the information identification unit Dd, and the control means 1 based on the information Check the surplus power generated by the input voltage change of the external power supply. Here, the surplus power generated by the change in the input voltage of the external power supply is a power that is not used as the planned power when the input voltage from the external power supply to the image forming apparatus is lowered. For example, when the input voltage from the external power supply becomes 90V with respect to the rated 100V 700W heater, the heater output power is about 600 W, and therefore, surplus power of about 100 W is generated.
(S42) It is confirmed whether or not the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S43) When the remaining power amount X is not larger than V2 (when X ≦ V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. Electric power is directly supplied from the charging device 1a using the confirmed surplus electric power, and is continued until the end of paper feeding.
(S44) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S45) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S46) When the power storage detector 7v detects X = V2, the changeover switch 9b is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. Electric power is directly supplied from the charging device 1a using the surplus power confirmed in S41, and is continued until the end of paper feeding.

Further, when surplus power generated by at least one of the peripheral device of the image forming apparatus is stopped, the peripheral device is not connected to the image forming apparatus, and the input voltage change of the external power supply is used, the configuration illustrated in FIG. In accordance with the control flow shown in FIG. 13, power supply control to the auxiliary heating element 2b is performed.
(S51) When paper feeding is started, the operation status of the peripheral device such as a scanner is confirmed by the internal operation confirmation unit 42, the operation information is sent to the information identification unit Dd, and the control means 1 is based on the operation information. The surplus power generated by the suspension of the peripheral device of the image forming apparatus is confirmed. The contents are the same as step S21 in FIG.
(S52) Also, the peripheral device connected to the image forming apparatus is confirmed by the peripheral device detection unit 41, and the connected peripheral device (peripheral device) information is sent to the information identification unit Dd, and the control means 1 includes the information. Based on this, the surplus power generated by the unconnected peripheral device to the image forming apparatus is confirmed. The content is the same as step S31 of FIG.
(S53) The input voltage value of the external power source is confirmed by the input voltage detection unit 40, and the input voltage value information is sent to the information identification unit Dd, and the control means 1 is caused by a change in the input voltage of the external power source based on the information. Check surplus power. The content is the same as step S41 of FIG.
(S54) It is confirmed whether the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S55) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 7A, and the auxiliary heating element 2b includes the steps S51, Electric power is directly supplied from the charging device 1a using the surplus electric power confirmed in S52 and S53, and is continued until the end of paper feeding. At this time, all of the surplus power confirmed in steps S51, S52, and S53 may be used, or any one or two of surplus power may be used.
(S56) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S57) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S58) When the power storage detector 7v detects X = V2, the changeover switch 9b is switched by the charge / discharge control unit 1A to enter the state of the heating device shown in FIG. Electric power is directly supplied from the charging device 1a using the surplus electric power confirmed in S51, S52, and S53, and is continued until the end of paper feeding. At this time, all of the surplus power confirmed in steps S51, S52, and S53 may be used, or any one or two of surplus power may be used.

  By the way, in the image forming process step on the sheet, as seen in the area surrounded by the dotted line in FIG. 6A, the temperature of the fixing roller 3 is suddenly lowered immediately after the start of paper feeding. This is because the heated pressure roller 4 and the sheet come into contact with the heated fixing roller 3 so that heat is taken away. In anticipation of this temperature drop, the temperature of the fixing roller 3 at the start of paper feeding is increased in advance, and thereafter, the temperature required for fixing is secured by heating by the heating element 2. However, when such a rapid temperature drop occurs, the temperature at the end of the fixing roller 3 may become a problem.

  Therefore, when the fixing member becomes a predetermined temperature or less after the image forming process on the sheet starts, the peripheral of the peripheral device, the change in the input voltage of the external power source, or the peripheral device is disconnected is caused. It is preferable to supply surplus power to the end heating means (end heater 2a2).

FIG. 14 is a control flow relating to power supply control to the heating unit 10 between time points b and d. At this time, the power supply control to the heating unit 10 described in FIG. 6 is performed at the same time.
(S61) When paper feeding is started, the surplus power in the image forming apparatus is confirmed. For example, in FIG. 9, the operation status of a peripheral device such as a scanner is confirmed by the internal operation confirmation unit 42, the operation information is sent to the information identification unit Dd, and the control unit 1 forms an image based on the operation information. The surplus power generated by the suspension of the peripheral devices of the device is confirmed (the content is the same as step S21 in FIG. 10). Alternatively, the peripheral device connected to the image forming apparatus is confirmed by the peripheral device detection unit 41, and information on the connected peripheral device (peripheral device) is sent to the information identification unit Dd, and the control unit 1 performs image processing based on the information. The surplus power generated by the unconnected peripheral device to the forming apparatus is confirmed (the content is the same as step S31 in FIG. 11). Alternatively, the input voltage value of the external power source is confirmed by the input voltage detection unit 40, and the input voltage value information is sent to the information identification unit Dd, and the control unit 1 generates a surplus caused by the change in the input voltage of the external power source based on the information. The power is confirmed (the content is the same as step S41 in FIG. 12).
(S62) Next, the temperature of the fixing roller 3 is confirmed by the temperature detecting means (temperature sensor) 8. Here, the surface temperature of the end portion of the fixing roller 3 is detected by the temperature detection means 8b, and the temperature information is sent to the information identification unit Dd. Based on the temperature information, the control unit 1 determines whether or not the fixing roller 3 is below a predetermined temperature T1 (for example, 100 ° C.).
(S63) When the fixing roller 3 is at a predetermined temperature T1 (for example, 100 ° C.) or less, the control unit 1 increases the power supplied to the end heater 2a2 using the surplus power confirmed in step S61. Let As a method of increasing the power at this time, surplus power may be added to the preset table control, or the duty may be increased by duty control. Then, the process returns to step S61.
When the fixing roller 3 is higher than a predetermined temperature T1 (for example, 100 ° C.), the process returns to step S61 as it is.

  The above control is performed until the end of paper feeding. As a result, the rapid temperature drop of the fixing roller 3 immediately after the start of paper feeding can be promptly improved. Here, when the temperature of the fixing roller 3 drops immediately after the start of paper feeding, it is conceivable to supply surplus power to the auxiliary heating element 2b by the charging device 1a. The charging power of the capacitor of the auxiliary power supply device 7 at this time is Since it is high (V1> E), heat is mainly generated by discharging the capacitor of the auxiliary power supply device 7, and the improvement effect is not so much. Therefore, the power is supplied to the control power of the main heating element 2a (particularly, the end heater 2a2) and used to drop the temperature at the start of paper feeding.

  Note that the remaining power amount X of the auxiliary power supply 7 is always monitored even during the control of FIG. 14 (that is, during paper passing), and the remaining power amount X is maintained even if the control in step S63 is performed. When the voltage reaches the dischargeable voltage V2, the power of the end heater 2a2 is returned to the original, and the surplus power is used to directly supply power from the charging device 1a to the auxiliary heating element 2b. That is, control in steps S14 and S15 in FIG. 8, control in steps S25 and S26 in FIG. 10, control in steps S35 and S36 in FIG. 11, control in steps S45 and S46 in FIG. 12, and steps S57 and S58 in FIG. Do one of the controls.

  As described above, if there is surplus power as the main body of the image forming apparatus, it is used for the main heating element 2a (particularly the end heater 2a2) to prevent the temperature drop when the fixing roller temperature drops at the start of paper feeding. Next, since the remaining power amount of the auxiliary power supply 7 decreases when the paper is continuously fed, the surplus power that has been turned to the main heating heater 2a (edge heater 2a2) when the dischargeable voltage is reached is supplemented. It switches to the direction supplied to the heat generating body 2b. As a result, the fixing roller 3 can be efficiently maintained at an appropriate temperature.

Next, a case where a small-size (for example, A5 size) sheet is passed through the image forming apparatus of the present invention will be described.
In the image forming apparatus of the present invention, when the discharge voltage of the power storage device (auxiliary power supply device 7) is equal to or lower than a predetermined voltage in the image forming process for a small-sized sheet, the fixing member (fixing roller 3) is Direct power from the charging device to the second heating means (auxiliary heating element 2b) using the power scheduled to be supplied to the end heating means (end heater 2a2) at a predetermined temperature (eg, 100 ° C.) or higher. Is preferably supplied.

  In the case of small size paper passing, the image forming apparatus according to the present invention is controlled in accordance with the small size paper passing control so that the heater corresponding to the non-sheet passing portion (here, the end heater 2a2) is not lit as much as possible. Specifically, the control is performed in a state where the control temperature based on the temperature detected by the temperature detecting means 8b at the end corresponding to the non-sheet passing portion is lower than the control temperature based on the temperature detected by the central temperature detecting means 8a. The reason is a measure for suppressing the temperature rise in the non-sheet passing portion. When the control is performed in the small-size sheet passing under this condition, basically, the end heater 2a2 is hardly turned on. At this time, since the power for lighting the end heater 2a2 is surplus, this surplus power is used for the auxiliary heating element 2b.

FIG. 15 is a control flow relating to power supply control to the heating unit 10 between the time points b and d when the small size paper is passed. Here, it is assumed that the power supply control to the heating unit 10 described in FIG. 6 is performed at the same time, and the remaining power amount X of the auxiliary power supply device 7 is the dischargeable voltage V2.
(S71) When the sheet feeding is started, the control unit 1 controls the power supply on the premise of the small size control.
(S72) Next, the surface temperature of the end portion of the fixing roller 3 is detected by the temperature detecting unit 8b, and the temperature information is sent to the information identifying unit Dd.
(S73) Based on the temperature information, the control unit 1 determines whether or not the fixing roller 3 is at a control temperature (for example, 100 ° C.) or less.
(S74) When the fixing roller 3 is below the control temperature (for example, 100 ° C.), the control unit 1 supplies power to the end heater 2a2 (end heater ON).
(S75) When the fixing roller 3 is higher than the control temperature (for example, 100 ° C.), the control unit 1 uses the power scheduled to be supplied to the end heater 2a2 from the charging device 1a to the auxiliary heating element 2b. To supply power directly.
The above control is repeated until the end of paper feeding.

  As a result, since the auxiliary heating element 2b is turned on by effectively using the surplus power at the time of passing the small size paper, the auxiliary heating element 2b that has stopped generating heat due to the loss of the charging voltage of the auxiliary power supply device 7 as in the prior art. The fixing roller 3 is no longer an obstacle to heating, and a reduction in electrothermal efficiency can be prevented.

  By the way, when the next job is input immediately after a large number of continuous sheets as a previous job (image forming process), the fixing roller 3 and the pressure roller 4 are sufficiently heated. Paper will be passed. At this time, there is no sudden drop in temperature of the fixing roller 3 immediately after the start of paper passing, as in the portion surrounded by the dotted line in FIG. For this reason, the temperature detected by the temperature detecting means 8a, 8b does not become lower than the control temperature, and the main heating element 2a (central heater 2a1, end heater 2a2) sometimes does not light up. On the other hand, since the interval between jobs is short, the capacitor of the auxiliary power supply device 7 is not sufficiently charged, and the remaining power amount X may become the dischargeable voltage V2 immediately after the start of paper feeding.

  Therefore, in the image forming apparatus of the present invention, when the discharge voltage of the power storage device (auxiliary power supply device 7) becomes equal to or lower than a predetermined voltage (dischargeable voltage V2) in the sheet image forming process, the fixing member ( When the fixing roller 3) is at a predetermined temperature or higher, the charging device uses the power to be supplied to the first heating means (central heater 2a1, end heater 2a2) from the charging device to the second heating means (auxiliary heating element 2b). It is preferable to supply power directly to.

  FIG. 16 is a control flow related to power supply control related to the main heating element 2a between time points b and d. Here, it is assumed that the power supply control to the heating unit 10 described in FIG. 6 is performed at the same time, and the remaining power amount X of the auxiliary power supply device 7 is the dischargeable voltage V2.

FIG. 16A shows power supply control related to the central heater 2a1.
(S81) When the sheet passing is started, the surface temperature of the center portion of the fixing roller 3 is detected by the temperature detecting unit 8a, and the temperature information is sent to the information identifying unit Dd.
(S82) Based on the temperature information, the control means 1 determines whether or not the fixing roller 3 is below the control temperature.
(S83) When the fixing roller 3 is below the control temperature, the control means 1 supplies power to the central heater 2a1 (central heater ON).
(S84) When the fixing roller 3 is higher than the control temperature, the control means 1 supplies power directly from the charging device 1a to the auxiliary heating element 2b using the power scheduled to be supplied to the central heater 2a1.
The above control is repeated until the end of paper feeding.

FIG. 16B shows power supply control related to the end heater 2a2.
(S91) When the sheet passing is started, the surface temperature of the end portion of the fixing roller 3 is detected by the temperature detecting unit 8b, and the temperature information is sent to the information identifying unit Dd.
(S92) Based on the temperature information, the control unit 1 determines whether or not the fixing roller 3 is below the control temperature.
(S93) When the fixing roller 3 is below the control temperature, the control means 1 supplies power to the end heater 2a2 (end heater ON).
(S94) When the fixing roller 3 is higher than the control temperature, the control unit 1 directly supplies power from the charging device 1a to the auxiliary heating element 2b using the power scheduled to be supplied to the end heater 2a2. .
The above control is repeated until the end of paper feeding.

  The above-described power supply control in FIGS. 16A and 16B may be performed by either one or both of the controls. In any case, since the auxiliary heating element 2b is lit by effectively using the surplus power, the auxiliary heating element 2b, which does not generate heat due to the loss of the charging voltage of the auxiliary power supply device 7 as in the prior art, is heated by the fixing roller 3. Therefore, it is possible to prevent a decrease in electrothermal efficiency.

Next, a second embodiment of the image forming apparatus according to the present invention will be described.
As shown in FIGS. 1 to 3, the image forming apparatus according to the present invention has a power storage device (auxiliary power supply device 7), a rotating fixing member (fixing roller 3), and a nip portion in contact with the fixing member. A pressure member to be formed (pressure roller 4), a first heating means (main heating element 2a) for heating the fixing member by power supply from an external power source (main power supply device 50), and power supply from the power storage device A fixing device (fixing device 36) having a second heating means (auxiliary heating element 2b) that heats the fixing member by a charging device, and a charging device (charging device 1a) that charges the power storage device. When the discharge voltage of the power storage device becomes equal to or lower than a predetermined voltage in the image forming process, the power storage device is discharged while being supplied with power supplied from the charging device, and power is supplied to the second heating unit. Supply.

A heating control process of the fixing device in the image forming apparatus of this embodiment will be described with reference to FIG.
6 shows the temperature of the fixing roller 3 during operation of the image forming apparatus of the present invention configured as shown in FIGS. 1 to 3 (FIG. 6A) and the power supplied to the heating unit 10 (FIG. 6B). FIG. 6 is a diagram showing changes in the discharged power of the main power supply device 50 (FIG. 6C) and the residual voltage of the auxiliary power supply device 7 (FIG. 6D). In this example, 100 continuous originals (75 CPM), ADF maximum stacking number 100 sheets, capacitor rated voltage 45 V as auxiliary power supply device 7, charging target value 44 V (V1, not fully charged to prevent deterioration) The discharge start permission range from the capacitor is 30 to 44 V, and the discharge end value is 20 V (the discharge time from the target voltage 44 V to the end value 20 V is 60 seconds, for example). When the voltage of the capacitor is less than 20V, the auxiliary heating element 2b of the heating unit 10 hardly generates heat, so the voltage 20V is set as the end threshold value (discharge stop voltage V ₃ ). Further, a dischargeable voltage _{V 2} to 25V.

  The temperature of the fixing roller 3 rises with the start of the start-up operation by the continuous copy command (time point a) from the state where not much power is consumed during standby, and moves to the sheet P by the start of the sheet passing operation (time point b). As a result, the temperature decreases, and then the temperature rises slightly until the end of document reading (time point c) and the end of copying (time point d), and the temperature decreases when returning to the standby operation. In addition, between the time points a and b is, for example, 30 seconds, between the time points b and c, for example, 60 seconds, and between the time points b and d, for example, 80 seconds.

  The power supplied to the heating unit 10 during this operation is from a power non-supply state (up to time point a) during standby, power supply by the main power supply device 50 (between time points a and b), and paper feeding operation during startup. Power supply by the main power supply device 50 and the auxiliary power supply device 7 (between time points b and c), power supply by the main power supply device 50 (between time points c and d) after completion of document reading, and a non-supply state during standby Return (after time d) changes. Details are as follows.

(1) Until time point a In the heating device of FIG. 3, both the triac 5b and the FET 6b are off, and the heating element 2 is not supplied with power. At this time, since the remaining power amount of the capacitor of the auxiliary power supply device 7 is in a standby state, the target value 44V (charging voltage V1) which is the maximum value is indicated.

(2) Between time points a and b In the heating device of FIG. 3, the triac 5b is turned on while the FET 6b is off, the heating power is supplied from the main power supply device 50 to the main heating element 2a, and the fixing roller 3 is kept at a predetermined temperature. The main heating element 2a is heated until it becomes. The power supply by the main power supply 50 increases from the non-supply state during standby to the normal power of the commercial power supply, which is the upper limit value (for example, the value of the rated power supply is 1200 W or the vicinity thereof) with the start of image formation. To do.

(3) Between time points b and c ′ As in the heating device of FIG. 3, both the triac 5b and the FET 6b are turned on, and at the same time, the changeover switches 9a and 9b are both on the contact (1) side. As a result, heating power is supplied from the main power supply device 50 to the main heating element 2a through the path indicated by a thick line in FIG. 3, and power from the capacitor discharge is supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b. Here, the power supply by the main power supply device 50 distributes the power to the image reading and other driving units, so that the power to the fixing device 36 is reduced more than between the time points a and b (for example, decreased to 800 W). To do). On the other hand, the power supply by the auxiliary power supply device 17 is a capacitor of the auxiliary power supply device 7 in order to prevent the temperature of the fixing roller 3 from being lowered due to a shortage of power supply during continuous paper feeding due to a decrease in power supply from the main power supply device 50. Is used to prevent a reduction in productivity such as a decrease in copy speed (CPM down) or stop until the temperature of the fixing roller 3 recovers during continuous paper feeding. At this time, the remaining power amount of the auxiliary power supply device 7 gradually decreases until the dischargeable voltage V2 is reached.

(4) Between time points c ′ and d As in the heating device of FIG. 17A, both the triac 5b and the FET 6b are turned on, and at the same time, the changeover switch 9a is on the contact (2) side and the changeover switch 9b is on the contact (1) side. It becomes. Thereby, the heating power is supplied from the main power supply device 50 to the main heating element 2a along the path indicated by the bold line in FIG. Further, the capacitor of the auxiliary power supply device 7 continues to be discharged, and the power of the main power supply device 50 is supplied from the charging device 1a to the auxiliary power supply device 7 to be charged. In other words, the capacitor of the auxiliary power supply device 7 is charged from the charging device 1a and discharged to supply power to the auxiliary heating element 2b, which can be said to be a state in which the balance of charging and discharging power is balanced. The discharge voltage of the auxiliary power supply device 7 at this time is the dischargeable voltage V2, and the auxiliary heating element 2b is supplied with electric power E1 for turning on the auxiliary heating element 2b even slightly. As the power supplied to the auxiliary power supply device 7 at this time, it is preferable to use surplus power as the image forming apparatus as will be described later. As a result, the auxiliary heating element 2b is turned on slightly, so that the auxiliary heating element 2b, which does not generate heat due to the loss of the charging voltage of the auxiliary power supply device 7 as in the prior art, does not become an obstacle to heating the fixing roller 3. A decrease in electrothermal efficiency can be prevented. Further, since the remaining power amount of the capacitor of the auxiliary power supply device 7 is held at the dischargeable voltage V2, it is possible to charge to the charging voltage V1 promptly and correspond to the next job.

(5) Between time points d and e As in the heating device of FIG. 17B, both the triac 5b and the FET 6b are turned off, and the change-over switches 9a and 9b are both on the contact (2) side. As a result, the supply of power to the heating unit 10 (heating element 2) is stopped, and power is supplied from the main power supply device 50 to the capacitor of the auxiliary power supply device 7 through the charging device 1a along the path indicated by the thick line in FIG. Is supplied and charging is performed. Then, when the remaining power amount of the auxiliary power supply device 7 reaches the charging voltage V1, the charging from the charging device 1a is stopped and enters a standby state.

The power supply control to the auxiliary heating element (capacitor heater) 2b between the time points b and d described above is a control flow shown in FIG.
(S101) When the sheet feeding is started, it is confirmed whether or not the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S102) When the remaining power amount X is not greater than V2 (when X ≦ V2), the state of the heating device shown in FIG. 17A is entered, and the capacitor of the auxiliary power supply device 7 is charged from the charging device 1a and discharged. Then, electric power is supplied to the auxiliary heating element 2b (capacitor charging + discharging), and the operation is continued until the end of paper feeding.
(S103) When the remaining power amount X is larger than V2 (when X> V2), the state of the heating device shown in FIG. 3 is established, and discharge power is supplied from the auxiliary power supply device 7 to the auxiliary heating element 2b.
(S104) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S105) When the power storage detector 7v detects X = V2, the changeover switch 9a is switched to the state of the heating device shown in FIG. 17A, and the capacitor of the auxiliary power supply device 7 is charged from the charging device 1a. Then, the electric power is discharged and power is supplied to the auxiliary heating element 2b (capacitor charging + discharging), and the operation is continued until the end of paper feeding.

  When the discharge voltage of the power storage device (auxiliary power supply device 7) becomes a predetermined voltage (for example, dischargeable voltage V2) or less in the image forming process step on the sheet, the surplus power of the image forming device is used. It is preferable to charge the auxiliary power supply device 7 by supplying power from the charging device (charging device 1a).

  Further, the surplus power of the image forming apparatus used at this time is surplus power generated by any of the following: the peripheral device of the image forming apparatus is stopped, the peripheral device is not connected to the image forming apparatus, or the input voltage of the external power supply is changed. Preferably there is.

  At this time, in order to use the surplus power of the image forming apparatus, it is necessary to detect cases of the peripheral device of the image forming apparatus being stopped, the peripheral device not being connected to the image forming apparatus, and the input voltage change of the external power source. is there. The configuration is as shown in the block diagram of the functional configuration of the main part of the heating device of the fixing device 36 shown in FIG.

When the surplus power generated by the suspension of the peripheral device of the image forming apparatus is used, the power supply control to the auxiliary heating element 2b between the time points b and d is performed according to the control flow shown in FIG. 19 on the premise of the configuration of FIG. .
(S201) When paper feeding is started, the operation status of the peripheral device such as a scanner is confirmed by the internal operation confirmation unit 42, the operation information is sent to the information identification unit Dd, and the control means 1 is based on the operation information. The surplus power generated by the suspension of the peripheral device of the image forming apparatus is confirmed. Here, the surplus power generated by the suspension of the peripheral device of the image forming apparatus is a surplus power due to the operating state of a motor or the like that is not operating when the image forming apparatus main body is operating (at the time of paper passing). For example, in the image forming apparatus shown in FIG. 1, when the automatic document feeder (ADF) 13 is not used at the time of paper passing, or when 100 originals set on the document table are copied, the reading unit 11 is used. This is the surplus power generated when no operation is performed after reading once, or when the one-sided copy is selected in the automatic document feeder (ADF) 13 having the double-sided simultaneous reading function and the back side is not read.
(S202) It is confirmed whether the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S203) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 17A, and the capacitor of the auxiliary power supply device 7 is in step S201. The confirmed surplus power is used for charging from the charging device 1a, and it is discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding.
(S204) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. Is supplied.
(S205) After that, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S206) When the power storage detector 7v detects X = V2, the changeover switch 9a is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. The surplus power confirmed in S201 is used for charging from the charging device 1a, and it is discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding.

  As described above, since the electric power is surplus depending on the operating state of the motor or the like that is not operating when the image forming apparatus main body is operating (when the paper is passed), the electric power is turned to the capacitor charging power of the auxiliary power supply device 7.

In addition, when surplus power generated by the disconnection of the peripheral device to the image forming apparatus is used, power supply to the auxiliary heating element 2b between time points b and d according to the control flow shown in FIG. 20 on the assumption of the configuration of FIG. Control is performed.
(S301) When the sheet passing is started, the peripheral device connected to the image forming apparatus is confirmed by the peripheral device detection unit 41, and the connected peripheral device (peripheral device) information is sent to the information identification unit Dd for control. The means 1 confirms the surplus power generated due to the unconnected peripheral device to the image forming apparatus based on the information. Here, as the surplus power generated when the peripheral device is not connected to the image forming apparatus, a peripheral device (for example, a finisher, a large-capacity paper feed tray, a cover feeder, or the like) is connected in various options in the image forming apparatus main body. The power supply from the external power supply is allocated so that it can be used in the future, but in actual use, it is rare to have a full system that connects all peripheral devices, and it is not connected at that time This corresponds to the amount of power assumed by the peripheral device. For example, when the peripheral device is detected and not connected, the surplus power is calculated according to a preset table. If there are several types of finishers depending on the specifications, a table is provided accordingly.
(S302) It is confirmed whether or not the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S303) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 17A, and the capacitor of the auxiliary power supply device 7 is in step S301. The confirmed surplus power is used for charging from the charging device 1a, and it is discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding.
(S304) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S305) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S306) When the power storage detector 7v detects X = V2, the changeover switch 9a is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. The surplus power confirmed in S301 is charged from the charging device 1a and discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding.

Further, when surplus power generated by the input voltage change of the external power supply is used, the power supply control to the auxiliary heating element 2b is performed between time points b and d according to the control flow shown in FIG. .
(S401) When the paper feeding is started, the input voltage value of the external power source is confirmed by the input voltage detection unit 40, and the input voltage value information is sent to the information identification unit Dd, and the control means 1 is based on the information. Check the surplus power generated by the input voltage change of the external power supply. Here, the surplus power generated by the change in the input voltage of the external power supply is a power that is not used as the planned power when the input voltage from the external power supply to the image forming apparatus is lowered. For example, when the input voltage from the external power supply becomes 90V with respect to the rated 100V 700W heater, the heater output power is about 600 W, and therefore, surplus power of about 100 W is generated.
(S402) It is confirmed whether the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S403) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charge / discharge control unit 1A enters the state of the heating device shown in FIG. 17A, and the capacitor of the auxiliary power supply device 7 is in step S401. The confirmed surplus power is used for charging from the charging device 1a, and it is discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding.
(S404) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S405) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S406) When the power storage detector 7v detects X = V2, the changeover switch 9a is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. The surplus power confirmed in S401 is charged from the charging device 1a, and discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding.

Further, when surplus power generated by at least one of the peripheral device of the image forming apparatus is stopped, the peripheral device is not connected to the image forming apparatus, and the input voltage change of the external power supply is used, the configuration illustrated in FIG. The power supply control to the auxiliary heating element 2b is performed according to the control flow shown in FIG.
(S501) When paper feeding is started, the operation status of a peripheral device such as a scanner is confirmed by the internal operation confirmation unit 42, the operation information is sent to the information identification unit Dd, and the control means 1 is based on the operation information. The surplus power generated by the suspension of the peripheral device of the image forming apparatus is confirmed. The content is the same as step S201 of FIG.
(S502) Further, the peripheral device connected to the image forming apparatus is confirmed by the peripheral device detection unit 41, and the connected peripheral device (peripheral device) information is sent to the information identification unit Dd, and the control means 1 includes the information. Based on this, the surplus power generated by the unconnected peripheral device to the image forming apparatus is confirmed. The content is the same as step S301 in FIG.
(S503) The input voltage value of the external power supply is confirmed by the input voltage detection unit 40, and the input voltage value information is sent to the information identification unit Dd, and the control means 1 is caused by a change in the input voltage of the external power supply based on the information. Check surplus power. The content is the same as step S401 in FIG.
(S504) It is confirmed whether or not the remaining power amount X of the auxiliary power supply device 7 detected by the power storage detector 7v is larger than the dischargeable voltage V2.
(S505) When the remaining power amount X is not greater than V2 (when X ≦ V2), the charge / discharge control unit 1A enters the state of the heating device shown in FIG. The surplus power confirmed in S502 and S503 is charged from the charging device 1a, and discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding. At this time, all of the surplus power confirmed in steps S501, S502, and S503 may be used, or any one or two of surplus power may be used.
(S506) When the remaining power amount X is larger than V2 (when X> V2), the charging / discharging control unit 1A enters the state of the heating device shown in FIG. 3, and the auxiliary heating element 2b receives the discharge power from the auxiliary power supply device 7. Is supplied.
(S507) Thereafter, when a large number of sheets are passed, the remaining power amount X reaches the dischargeable voltage V2.
(S508) When the power storage detector 7v detects X = V2, the changeover switch 9a is switched by the charge / discharge control unit 1A, and the state of the heating device shown in FIG. The surplus power confirmed in S501, S502, and S503 is charged from the charging device 1a, and discharged to supply power to the auxiliary heating element 2b (capacitor charging + discharging), and is continued until the end of paper feeding. At this time, all of the surplus power confirmed in steps S501, S502, and S503 may be used, or any one or two of surplus power may be used.

  By the way, in the image forming process step on the sheet, as seen in the area surrounded by the dotted line in FIG. 6A, the temperature of the fixing roller 3 is suddenly lowered immediately after the start of paper feeding. This is because the heated pressure roller 4 and the sheet come into contact with the heated fixing roller 3 so that heat is taken away. In anticipation of this temperature drop, the temperature of the fixing roller 3 at the start of paper feeding is increased in advance, and thereafter, the temperature required for fixing is secured by heating by the heating element 2. However, when such a rapid temperature drop occurs, the temperature at the end of the fixing roller 3 may become a problem.

  Therefore, when the fixing member becomes a predetermined temperature or less after the image forming process on the sheet starts, the peripheral of the peripheral device, the change in the input voltage of the external power source, or the peripheral device is disconnected is caused. It is preferable to supply surplus power to the end heating means (end heater 2a2). The control flow regarding the power supply control to the heating unit 10 at this time may be the same as that in FIG.

  As a result, the rapid temperature drop of the fixing roller 3 immediately after the start of paper feeding can be promptly improved. Here, when the temperature of the fixing roller 3 drops immediately after the start of paper feeding, it is conceivable to supply surplus power from the charging device 1a to the auxiliary power supply device 7. At this time, the charging power of the capacitor of the auxiliary power supply device 7 is Since it is high (V1> E), there is not much improvement effect. Therefore, the power is supplied to the control power of the main heating element 2a (particularly, the end heater 2a2) and used to drop the temperature at the start of paper feeding.

  Note that the remaining power amount X of the auxiliary power supply 7 is always monitored even during the control of FIG. 14 (that is, during paper passing), and the remaining power amount X is maintained even if the control in step S63 is performed. Becomes the dischargeable voltage V2, the power of the end heater 2a2 is restored, and the capacitor of the auxiliary power supply device 7 is charged from the charging device 1a using the surplus power and discharged to generate auxiliary heat. Electric power is supplied to the body 2b (capacitor charge + discharge). That is, control in steps S104 and S105 in FIG. 18, control in steps S205 and S206 in FIG. 19, control in steps S305 and S306 in FIG. 20, control in steps S405 and S406 in FIG. 21, and steps S507 and S508 in FIG. Do one of the controls.

  As described above, if there is surplus power as the main body of the image forming apparatus, it is used for the main heating element 2a (particularly the end heater 2a2) to prevent the temperature drop when the fixing roller temperature drops at the start of paper feeding. Next, since the remaining power amount of the auxiliary power supply 7 decreases when the paper is continuously fed, the surplus power that has been turned to the main heating heater 2a (edge heater 2a2) when the dischargeable voltage is reached is supplemented. It switches to the direction which supplies to the power supply device 7. As a result, the fixing roller 3 can be efficiently maintained at an appropriate temperature.

Next, a case where a small-size (for example, A5 size) sheet is passed through the image forming apparatus of the present invention will be described.
In the image forming apparatus of the present invention, when the discharge voltage of the power storage device (auxiliary power supply device 7) is equal to or lower than a predetermined voltage in the image forming process for a small-sized sheet, the fixing member (fixing roller 3) is When the temperature is equal to or higher than a predetermined temperature (for example, 100 ° C.), the power storage device is supplied from the charging device (charging device 1a) using the power scheduled to be supplied to the end heating means (end heater 2a2). It is preferable to supply electric power to the second heating means (auxiliary heating element 2b) by discharging while being charged.

  In the case of small size paper passing, the image forming apparatus according to the present invention is controlled in accordance with the small size paper passing control so that the heater corresponding to the non-sheet passing portion (here, the end heater 2a2) is not lit as much as possible. Specifically, the control is performed in a state where the control temperature based on the temperature detected by the temperature detecting means 8b at the end corresponding to the non-sheet passing portion is lower than the control temperature based on the temperature detected by the central temperature detecting means 8a. The reason is a measure for suppressing the temperature rise in the non-sheet passing portion. When the control is performed in the small-size sheet passing under this condition, basically, the end heater 2a2 is hardly turned on. At this time, since the power for lighting the end heater 2a2 is surplus, this surplus power is used for charging the auxiliary power supply 7.

FIG. 23 is a control flow relating to power supply control to the heating unit 10 between the time points b and d when the small size paper is passed. Here, it is assumed that the power supply control to the heating unit 10 described in FIG. 6 as the second embodiment is performed at the same time, and the remaining power amount X of the auxiliary power supply device 7 is the dischargeable voltage V2.
(S701) When paper feeding is started, the control means 1 controls power supply on the premise of small size control.
(S702) Next, the surface temperature of the end portion of the fixing roller 3 is detected by the temperature detecting unit 8b, and the temperature information is sent to the information identifying unit Dd.
(S703) The control unit 1 determines whether or not the fixing roller 3 is at a control temperature (for example, 100 ° C.) or less based on the temperature information.
(S704) When the fixing roller 3 is below the control temperature (for example, 100 ° C.), the control unit 1 supplies power to the end heater 2a2 (end heater ON).
(S705) When the fixing roller 3 is higher than the control temperature (for example, 100 ° C.), the capacitor of the auxiliary power supply device 7 is controlled by the control of the control unit 1 using the power scheduled to be supplied to the end heater 2a2. Is discharged from the charging device 1a while being charged and supplies power to the auxiliary heating element 2b (capacitor charging + discharging).
The above control is repeated until the end of paper feeding.

  As a result, since the auxiliary heating element 2b is turned on by effectively using the surplus power at the time of passing the small size paper, the auxiliary heating element 2b that has stopped generating heat due to the loss of the charging voltage of the auxiliary power supply device 7 as in the prior art. The fixing roller 3 is no longer an obstacle to heating, and a reduction in electrothermal efficiency can be prevented.

  By the way, when the next job is input immediately after a large number of continuous sheets as a previous job (image forming process), the fixing roller 3 and the pressure roller 4 are sufficiently heated. Paper will be passed. At this time, there is no sudden drop in temperature of the fixing roller 3 immediately after the start of paper passing, as in the portion surrounded by the dotted line in FIG. For this reason, the temperature detected by the temperature detecting means 8a, 8b does not become lower than the control temperature, and the main heating element 2a (central heater 2a1, end heater 2a2) sometimes does not light up. On the other hand, since the interval between jobs is short, the capacitor of the auxiliary power supply device 7 is not sufficiently charged, and the remaining power amount X may become the dischargeable voltage V2 immediately after the start of paper feeding.

  Therefore, in the image forming apparatus of the present invention, when the discharge voltage of the power storage device (auxiliary power supply device 7) becomes equal to or lower than a predetermined voltage (dischargeable voltage V2) in the sheet image forming process, the fixing member ( When the fixing roller 3) is equal to or higher than a predetermined temperature, the power storage device uses the power scheduled to be supplied to the first heating means (central heater 2a1, end heater 2a2), and the power storage device is connected to the charging device (charging device 1a). It is preferable to supply power to the second heating means (auxiliary heating element 2b) by discharging while being supplied and charged.

  FIG. 24 is a control flow relating to power supply control related to the main heating element 2a between time points b and d. Here, it is assumed that the power supply control to the heating unit 10 described in FIG. 6 as the second embodiment is performed at the same time, and the remaining power amount X of the auxiliary power supply device 7 is the dischargeable voltage V2.

FIG. 24A shows power supply control related to the central heater 2a1.
(S801) When the sheet passing is started, the surface temperature of the central portion of the fixing roller 3 is detected by the temperature detecting unit 8a, and the temperature information is sent to the information identifying unit Dd.
(S802) The control unit 1 determines whether or not the fixing roller 3 is below the control temperature based on the temperature information.
(S803) When the fixing roller 3 is below the control temperature, the control means 1 supplies power to the central heater 2a1 (central heater ON).
(S804) When the fixing roller 3 is higher than the control temperature, the auxiliary power supply device 7 is supplied from the charging device 1a by using the power scheduled to be supplied to the central heater 2a1 under the control of the control means 1. While being charged, it is discharged to supply power to the auxiliary heating element 2b.
The above control is repeated until the end of paper feeding.

FIG. 24B shows power supply control related to the end heater 2a2.
(S901) When paper feeding is started, the surface temperature of the end portion of the fixing roller 3 is detected by the temperature detecting unit 8b, and the temperature information is sent to the information identifying unit Dd.
(S902) The control means 1 determines whether or not the fixing roller 3 is below the control temperature based on the temperature information.
(S903) When the fixing roller 3 is below the control temperature, the control means 1 supplies power to the end heater 2a2 (end heater ON).
(S904) When the fixing roller 3 is higher than the control temperature, the auxiliary power supply device 7 is supplied from the charging device 1a by using the power scheduled to be supplied to the end heater 2a2 under the control of the control means 1. While being charged, the battery is discharged and power is supplied to the auxiliary heating element 2b.
The above control is repeated until the end of paper feeding.

  The power supply control in FIGS. 24A and 24B described above may be performed by either one or both. In any case, since the auxiliary heating element 2b is lit by effectively using the surplus power, the auxiliary heating element 2b, which does not generate heat due to the loss of the charging voltage of the auxiliary power supply device 7 as in the prior art, is heated by the fixing roller 3. Therefore, it is possible to prevent a decrease in electrothermal efficiency.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

  For example, in the embodiment described above, various controls are performed by the control means 1 provided in the heating device. However, the present invention is not limited to this, and the fixing device 36 or the image forming apparatus provided with the fixing device 36 is provided. Control means may be provided and control may be performed by this, and in any case, a dedicated control means for controlling the discharge voltage may be provided, or any other control means may be used. But you can.

  Further, for example, in the embodiment described above, a configuration in which the nip portion N is formed by two rollers, that is, the fixing roller 3 and the pressure roller 4 is shown. However, the image forming apparatus of the present invention has such a configuration. The invention is not limited, and various configurations such as a roller and a belt, a belt and a belt that form a nip portion N, and a type in which a sheet P passes through or close to a heated body can be employed. The present invention is not limited to the illustrated type of image forming apparatus. For example, the photosensitive member is not a drum but a belt type, and a color image forming apparatus using an intermediate transfer belt. Applicable. Furthermore, not only those using capacitors as auxiliary power supply devices, but also those using other capacitors such as secondary batteries may be used.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a fixing device used in the present invention. It is a circuit state diagram (1) of the heating device in the fixing device used in the present invention. It is a figure which shows the discharge characteristic of the capacitor which comprises an auxiliary power supply device. FIG. 10 is a diagram illustrating changes in fixing roller temperature, power supplied to a heating unit, discharge power of a main power supply, and remaining voltage of an auxiliary power supply during operation of a conventional image forming apparatus. FIG. 6 is a diagram illustrating changes in fixing roller temperature, power supplied to a heating unit, discharge power of a main power supply, and residual voltage of an auxiliary power supply during operation of the image forming apparatus of the present invention. 1 is a circuit state diagram of a heating device in a fixing device used as a first embodiment of an image forming apparatus of the present invention. It is a figure which shows the electric power supply control flow (1) to the auxiliary heat generating body in 1st Embodiment of the image forming apparatus of this invention. FIG. 3 is a block diagram illustrating a functional configuration of a main part of a heating device of a fixing device in the image forming apparatus of the present invention. It is a figure which shows the electric power supply control flow (2) to the auxiliary heat generating body in 1st Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (3) to the auxiliary heat generating body in 1st Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (4) to the auxiliary heat generating body in 1st Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (5) to the auxiliary heat generating body in 1st Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow to the heating part in the image forming apparatus of this invention. FIG. 5 is a diagram illustrating a flow of control of power supply to a heating unit when a small size is passed in the first embodiment of the image forming apparatus of the present invention. It is a figure which shows the electric power supply control flow to the main heat generating body in 1st Embodiment of the image forming apparatus of this invention. FIG. 6 is a circuit state diagram of a heating device in a fixing device used as a second embodiment of the image forming apparatus of the present invention. It is a figure which shows the electric power supply control flow (1) to the auxiliary heat generating body in 2nd Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (2) to the auxiliary heat generating body in 2nd Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (3) to the auxiliary heat generating body in 2nd Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (4) to the auxiliary heat generating body in 2nd Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow (5) to the auxiliary heat generating body in 2nd Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow to the heating part at the time of small size paper passing in 2nd Embodiment of the image forming apparatus of this invention. It is a figure which shows the electric power supply control flow to the main heat generating body in 2nd Embodiment of the image forming apparatus of this invention.

Explanation of symbols

1 Control means (CPU)
1A Charge / Discharge Control Unit 1a Charging Device 2, 2a, 2b, 2a1, 2a2 Heating Element 3 Fixing Roller 4 Pressure Roller 5a, 6a Controller 5b Triac 6b FET
7 Auxiliary power supply device 8, 8a, 8b, 8c Temperature detection means 9a, 9b Changeover switch 10 Heating unit 11 Reading unit 12 Image forming unit 13 Automatic document feeder (ADF)
DESCRIPTION OF SYMBOLS 14 Document discharge tray 15-18 Paper feed cassette 19 Paper feed part 20 Paper discharge tray 21 Document stand 22 Pickup roller 23 Document conveyance belt 24 Contact glass 25 Reading device 26 Light source 27 Optical system 28 Photoelectric conversion element 30 Photoconductor 31 Charging device 32 Writing unit 33 Developing device 34 Transfer device 35 Cleaning device 36 Fixing device 37 Discharge roller pair 40 Input voltage detection unit 41 Peripheral device detection unit 42 Internal operation confirmation unit 50 Main power supply device Ca Control execution unit Csw Copy start button Dd Information identification unit P sheet (recording medium)
T Toner

Claims (6)

A power storage device;
A fixing member that rotates, a pressure member that contacts the fixing member to form a nip portion, a first heating unit that heats the fixing member by power supply from an external power source, and fixing by power supply from the power storage device A second heating means for heating the member;
A charging device that receives power supply from the external power source and charges the power storage device,
When the discharge voltage of the power storage device becomes a predetermined voltage or less in the image forming process step on the sheet,
An image forming apparatus that stops discharging of the power storage device and directly supplies electric power for slightly lighting the second heating unit from the charging device to the second heating unit. When the discharge voltage of the power storage device becomes a predetermined voltage or less in the image forming process step on the sheet,
Using the surplus power of the image forming apparatus generated by at least one of the peripheral device pause, the peripheral device not connected, and the input voltage change of the external power supply, the second heating unit is connected from the charging device to the second heating unit. The image forming apparatus according to claim 1, wherein power for slightly lighting is directly supplied. The first heating unit includes an end heating unit that heats an end of the fixing member by supplying power from an external power source,
When the fixing member becomes a predetermined temperature or less after the image forming process on the sheet starts,
2. The image forming apparatus according to claim 1, wherein surplus power of the image forming apparatus generated by at least one of a peripheral apparatus pause, a peripheral apparatus not connected, and an input voltage change of an external power supply is supplied to the end heating unit. The first heating unit includes an end heating unit that heats an end of the fixing member by supplying power from an external power source,
When the discharge voltage of the power storage device is equal to or lower than a predetermined voltage in the image forming process on the small-sized sheet,
2. The image forming apparatus according to claim 1, wherein when the fixing member is equal to or higher than a predetermined temperature, power is supplied directly from the charging device to the second heating unit using power scheduled to be supplied to the end heating unit. When the discharge voltage of the power storage device becomes a predetermined voltage or less in the image forming process step on the sheet,
2. The image forming apparatus according to claim 1, wherein when the fixing member is equal to or higher than a predetermined temperature, power is supplied directly from the charging device to the second heating unit using power scheduled to be supplied to the first heating unit. The image forming apparatus according to claim 1, wherein the predetermined voltage is a dischargeable voltage of the power storage device.