JP2005221696A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus whose rise time is short and copying speed is high under any power supply circumstances by a commercial power source. <P>SOLUTION: The image forming apparatus is equipped with a capacitor 17 charged by a commercial power source 16, a heating part to which power is supplied from the power source 16 and the capacitor, and a fixing member heated by the heating part. An unfixed image is heated by the fixing member and fixed on a recording medium. The apparatus is equipped with a voltage detection part 1b for detecting the voltage of the power source 16, and a control part (CPU 11) for charging the capacitor 17 by using the power source 16 until the voltage of the capacitor 17 becomes equal to or above target voltage. The CPU 11 raises the target voltage when the voltage detected by the detection part 1b decreases. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including a fixing device system having a capacitor that supplies electric power to a heating unit.

  In recent image forming apparatuses such as copying machines, printers, and facsimiles, a toner image is formed on a recording medium such as transfer paper by an electrophotographic method, and then the toner is passed through a fixing device to heat the toner. In general, a toner image is fixed to the toner image.

  Further, in such a fixing device, the heat is generated by heating a roller or an endless belt due to heat generated by a heated body, and the toner is heated by bringing a fixing member such as the roller or the endless belt into contact with the recording medium. I have to. Here, the power supply to the heating element is generally from a commercial AC power supply, but recently, a fixing device system that supplies power to the heating element in combination with a capacitor has also been developed (see, for example, Patent Document 1). .)

  In other words, the image forming apparatus is required to shorten the total copying time from the start-up of the apparatus to the end of copying. However, the image forming apparatus is started up when the main power is turned on from the state where the fixing device system is not in operation. In this case, power is supplied to a plurality of heating elements from a commercial AC power supply and a condenser respectively, the fixing member is heated, and the temperature can be rapidly raised to the reload temperature, reducing the waiting time until the device can be used. As a result, the total copying time can be shortened.

JP 2002-174988 A

  However, although the image forming apparatus is configured to give top priority to ensuring image quality, image quality may be deteriorated due to poor fixing.

  Further, in the image forming apparatus, it has been difficult to achieve both a long life of the capacitor and ensuring high image quality.

  The present invention has been made in view of the above-described problems in the prior art, and provides an image forming apparatus having a short copying time and a high copying speed regardless of the power supply state of any commercial power source. With the goal. It is another object of the present invention to provide an image forming apparatus capable of achieving both a long life of a capacitor and ensuring good image quality.

  The present invention provided to solve the above-mentioned problems includes a battery charged by a commercial power supply, a heating part supplied with power from the commercial power supply and the battery, and a fixing member heated by the heating part, In an image forming apparatus that heats an unfixed image by a fixing member and fixes the unfixed image on a recording medium, until the voltage of the commercial power source detects the voltage of the commercial power source and the voltage of the capacitor becomes equal to or higher than a target voltage And a control unit that charges the battery by the commercial power source, and the control unit changes the target voltage to be higher when a detection voltage of the voltage detection unit is lowered. .

  In addition, the present invention provided to solve the above-described problems includes a capacitor charged by a commercial power source, a heating unit supplied with power from the commercial power source and the capacitor, and a fixing member heated by the heating unit. In the image forming apparatus for heating the unfixed image by the fixing member and fixing the unfixed image on the recording medium, the voltage detection unit for detecting the voltage of the commercial power supply and the total rated power of the heating unit are changed. And a control unit that increases the total rated power of the heating unit when the detection voltage of the voltage detection unit decreases.

  Here, it is preferable that the heating unit includes a plurality of heaters, and the control unit selects one or more of the heaters to change the total rated power of the heating unit.

  In addition, the present invention provided to solve the above-described problems includes a capacitor charged by a commercial power source, a heating unit supplied with power from the commercial power source and the capacitor, and a fixing member heated by the heating unit. In the image forming apparatus that heats an unfixed image by the fixing member and fixes the unfixed image on a recording medium, control for charging the capacitor by the commercial power supply until the voltage of the capacitor becomes equal to or higher than a target voltage. An image forming apparatus, wherein the capacitor has a cell capacity of 500 F or more and the target voltage is 80% or more of a cell rated voltage.

According to the present invention, even if the supply power of the commercial power supply is reduced, the necessary heat generation amount of the heating unit can be maintained, so that the startup time of the apparatus is short and the user-friendliness is high for the copying speed. A good image forming apparatus can be provided.
Further, it is possible to provide an image forming apparatus capable of extending the life of the battery while preventing poor fixing and ensuring good image quality.

Hereinafter, a configuration that is a premise of the embodiment of the present invention will be described.
FIG. 14 shows an example of a fixing device. In the fixing device of FIG. 14, a pressure roller 92 is pressed against a fixing roller 91, which is an embodiment of a fixing member, by a pressing unit (not shown) with a constant nip pressure. In the drawing, the fixing roller 91 rotates in the clockwise direction, and the pressure roller 92 rotates in the counterclockwise direction. In addition, the fixing roller 91 includes heaters 93 and 94 that are one aspect of a heating unit that generates heat when supplied with electric power, and the surface of the fixing roller 91 can fix toner by the heating of the heaters 93 and 94. It is temperature. Note that the surface temperature of the fixing roller 91 is monitored by a temperature detecting means 95 such as a temperature detecting means for detecting the temperature in contact with the surface of the fixing roller 91.

  When the image forming process is performed in the image forming apparatus, the sheet P, which is a recording medium carrying the toner T that is an unfixed image by the electrophotographic method, passes through the nip portion between the heated fixing roller 91 and the pressure roller 92. At this time, the toner T is fixed to the sheet P by being heated by the fixing roller 91 and the pressure roller 92. At this time, predetermined heat is required for the toner T to be fixed to the sheet P, and for this reason, the heaters 93 and 94 are set so that the surface temperature of the fixing roller 91 becomes a reload temperature at which the toner T can be fixed. Power supply to is controlled.

  FIG. 15 shows a circuit configuration example of the fixing device system. In FIG. 15, the heater 93 generates heat by electric power supplied from an external power supply (commercial power supply) 86, and the heater 94 is configured to generate heat by electric power supplied from a capacitor 87 that is one mode of the power storage unit. The heater 94 is preferably one in which a plurality of heaters are connected in parallel with the capacitor 87, and any one or all of these heaters may be connected to the capacitor 87 by switching a switch (not shown). For example, all heaters are connected to the capacitor 87 when the apparatus is started up, and any selected heater is connected when paper is passed.

  The capacitor voltage, which is an index of the stored energy (remaining power amount) of the capacitor 87 detected by the storage detector 88, and the temperature of the fixing roller 91 detected by the temperature detecting means 95 are respectively controlled through the input circuit as detection signals. CPU 81, which is one aspect of the unit. The CPU 81 energizes the heater 93 via the triac 83 and energizes the heater 94 via the FET 85 so that the surface temperature of the fixing roller 91 becomes a set temperature based on detection signals from the power storage detector 88 and the temperature sensor 95. Are controlled by controllers 82 and 84, respectively. Note that the capacitor 87 is connected to the charging device 8a by the switching of the switch 89 and can be charged. The capacitor 87 is connected with a power storage detector 88.

An example of the operation of the fixing device system is shown in FIG. In this case, the preconditions are as follows.
-CPM (number of copies per minute) condition: 75 CPM
・ Capacitor charge target voltage: 40V (Capacitor rated voltage: 45V)
-Copy command: 100 sheets continuously passed-Capacitor voltage at copy command: 40V

(S81) The capacitor voltage (40V) of the capacitor 87 is detected by the power storage detection unit 88, and the detection signal is captured by the CPU 81 to confirm that the capacitor voltage (40V) is equal to or higher than the target voltage (40V). The capacitor 87 enters a discharge standby state.
(S82) When a continuous copy command is issued by the copy start button, the apparatus starts up, power supply from the commercial power source 86 to the heater 93 is started, and the fixing roller 91 is heated. It takes 30 s as a startup time. At this time, the capacitor 87 is in a standby state.
(S83) Paper feeding is started at 75 CPM, and power is supplied from the commercial power source 86 to the heater 93 and from the capacitor 87 to the heater 94. While the fixing roller 91 is heated by the heat generated by the heaters 93 and 94, the sheet P carrying the toner T continuously passes through the nip portion between the fixing roller 91 and the pressure roller 92, and fixing is performed.

  At this time, in spite of the power supply from the commercial power source 86 and the capacitor 87 to the heater, fixing failure may occur.

The inventors analyzed the occurrence of this problem and found that a fixing failure occurred due to a voltage drop (92 V in FIG. 16) of the commercial power source 86.
That is, since the power from the commercial power source 86 is constant (for example, 100 V, 15 A), and the power is subtracted from the power required for the fixing device, the insufficient power is set as the power supplied from the capacitor 87. The voltage drop of the commercial power supply 86 is insufficient for heating the fixing roller, causing the temperature to fall below the reload temperature.

  In recent offices, not only OA devices but also various electronic and electric devices such as personal computers are supplied with power from a commercial power source 86. The commercial power source 86 cannot always supply constant power (100V, 15A). It turned out to be in the situation. Furthermore, the degree of voltage drop due to the influence of electronic and electrical equipment varies from office to office, and it has been difficult to prevent poor fixing in the image forming apparatus.

  The inventors have obtained the idea of monitoring the voltage of the commercial power supply 86 and have intensively studied. As a result, the present invention has been accomplished to solve the above problems by efficiently utilizing the capacitor.

  A first embodiment of an image forming apparatus according to the present invention will be described below. In addition, embodiment shown below is an illustration and is not limited to this.

FIG. 1 is a cross-sectional view showing a configuration of a fixing device according to the present invention.
The fixing device shown in FIG. 1 is in contact with the fixing roller 1 heated by the heating unit including the heaters 3 and 4, the pressure roller 2 that presses the fixing roller 1 with a constant nip pressure, and the surface temperature of the fixing roller 1. And temperature detecting means 5 for detecting.

  The fixing roller 1 is usually a hollow cylindrical roller, but may be in the form of an endless belt. Further, the fixing device 10 is stationary when the sheet rises, and rotates clockwise in the drawing when the sheet is passed.

  The pressure roller 2 is usually a cylindrical roller whose surface is made of an elastic member such as silicone rubber, but may be in the form of an endless belt. The pressing roller 2 is pressed against the fixing roller 1 by being pressed in the direction of the fixing roller 1 with a constant pressure by a pressing means (not shown). The pressure roller 2 is also stationary when the fixing device rises, and rotates counterclockwise in the figure when the sheet is passed. The rotation driving of the fixing roller 1 and the pressure roller 2 is performed by a driving mechanism (not shown).

  The temperature detecting means 5 is disposed on the opposite side of the nip portion with the central axis of the fixing roller 1 as the temperature detection position. In addition, any thermometer that can detect the surface temperature of the fixing roller 1 may be a contact thermometer, a non-contact thermometer, a thermocouple, or the like.

The heaters 3 and 4 are rod-shaped heaters which are one embodiment of the heating element, and the cross-sectional shape is shown in the drawing.
The heater 3 generates heat when power is supplied from an external power source such as a commercial power source that can always supply power, and heats the fixing roller 1 by the radiant heat.
The heater 4 generates heat when power is supplied from a capacitor which is an aspect of the battery, and the fixing roller 1 is heated by the radiant heat. The heater 4 is maintained at an appropriate fixing roller temperature by power control means such as on / off control. Yes.

FIG. 2 is a circuit diagram of the fixing device system according to the present invention.
The fixing device system 10 is different from the configuration that is the premise of the embodiment of the present invention shown in FIG. 11 in that it has a voltage detection unit 1b that detects the voltage of the commercial power supply 16 and the CPU 11; And the controller 12 related to the control of the power supply of the commercial power supply 16, the commercial power supply 16 connected to the heater 3, the capacitor 17 connected to the heater 4, the power storage detector 18 connected to the capacitor 17, and A controller 14 relating to control of power supply to the triac 13 and capacitor 17, an FET 15, a switch 19, and a charging device 1 a are provided.

  Further, the capacitor 17 is preferably a capacitor having a large capacitance such as an electric double layer capacitor having a capacitance larger than the Farad order.

  The CPU 11 detects the capacitor voltage as an index of the stored energy (remaining power amount) of the capacitor 17 detected by the storage detector 18, the temperature of the fixing roller 1 detected by the temperature detecting means 5, and the voltage detection unit 1b. The voltage of the commercial power supply 16 is captured as a detection signal.

  FIG. 3 is a block diagram relating to the target voltage change based on the voltage drop of the commercial power supply in the present invention. In FIG. 3, the CPU 11 is configured to include an information analysis unit Dd, a determination unit 11c, a target voltage setting unit 11e, and a control execution unit Ca that functionally configures a charge / discharge control unit 11A.

  The information analysis unit Dd takes in the voltage information of the commercial power source 16 detected by the voltage detection unit 1b and the storage energy information of the capacitor 17 detected by the storage detector 18.

  The determination unit 11c has a function of determining whether or not there is a voltage drop from the acquired voltage information of the commercial power supply 16 and whether or not the target voltage set by the target voltage setting unit 11e is reached from the capacitor voltage information of the capacitor 17. . Here, the determination unit 11c has a threshold value (commercial power supply voltage threshold value) for determining whether or not the commercial power supply 16 has a voltage drop. For example, assuming that the threshold value is 93V, it is determined that there is no voltage drop if the voltage information of the commercial power supply 16 is 93V or more, and it is determined that there is a voltage drop if the voltage information is less than 93V.

  The target voltage setting unit 11e has a function of setting a target voltage for charging the capacitor 17 based on the determination result of the determination unit 11c regarding the voltage drop of the commercial power supply 16. Specifically, if the determination result is no voltage drop of the commercial power supply 16, the target voltage is set to a reference voltage (for example, 40V in the case of the capacitor rated voltage 45V), and if the voltage drop is set, the target voltage is set to the reference. Is set to a voltage (for example, 43 V) that is increased from the above voltage.

  The charge / discharge control unit 11 </ b> A has a function of switching the switch 19 based on the determination result of the determination unit 11 c regarding the capacitor voltage of the capacitor 17 to control charging of the capacitor 17. Specifically, if the capacitor voltage of the capacitor 17 is equal to or higher than the target voltage, the switch 19 is switched to the heater 4 side to place the capacitor 17 in a discharge standby state, and if the capacitor voltage is lower than the target voltage, the switch 19 is set to the charging device 1a side. To charge the capacitor 17.

An example of the operation of the fixing device system of the present invention is shown in FIG. In this case, the preconditions are as follows.
-CPM conditions: 75 CPM
・ Capacitor charging target voltage: (Capacitor rated voltage: 45V)
40V (target value A) when commercial power supply voltage ≧ 93V
43V (target value B) for commercial power supply voltage <93V
-Copy command: 100 sheets continuously passed-Voltage drop of commercial power supply: Decrease from 100V to 92V-Capacitor voltage when voltage of commercial power supply drops: 40V

(S11) The voltage of the commercial power supply 16 drops (100V → 92V), and the voltage detection information (92V) of the commercial power supply 16 detected by the voltage detection unit 1b passes through the information analysis unit Dd in the CPU 11 to determine the determination unit 11c. Is taken in.
(S12) Since the voltage detection information (92V) is less than the commercial power supply voltage threshold (93V), the determination unit 11c determines that the commercial power supply 16 has a voltage drop.
(S13) Based on the determination result (with voltage drop) of the determination unit 11c, the target voltage at which the capacitor 17 is charged by the target voltage setting unit 11e is changed from 40V (target value A) to 43V (target value B). Is set.
(S14) Capacitor voltage detection information (40V) of the capacitor 17 detected by the power storage detector 18 is taken into the determination unit 11c via the information analysis unit Dd in the CPU 11.
(S15) The determination unit 11c determines that the capacitor voltage detection information (40V) is less than the target voltage (43V).
(S16) Based on the determination result (less than the target voltage) of the determination unit 11c, the switch 19 is switched to the charging device 1a side by the charge / discharge control unit 11A, and charging of the capacitor 17 is started.
(S17) The capacitor voltage of the capacitor 17 reaches 43V, and the capacitor voltage detection information (43V) detected by the power storage detector 18 is taken into the determination unit 11c via the information analysis unit Dd in the CPU 11.
(S18) The determination unit 11c determines that the capacitor voltage detection information (43V) is equal to or higher than the target voltage (43V).
(S19) Based on the determination result (above the target voltage) of the determination unit 11c, the charge / discharge control unit 11A switches the switch 19 to the heater 4 side, and the capacitor 17 enters the discharge standby state.

(S1a) When a continuous copy command is issued by the copy start button, the power supply to the heater 3 is started from the commercial power supply 16 at a voltage of 92 V when the apparatus is started up, whereby the fixing roller 1 is heated and the start-up time is increased. 30 s is required. At this time, the capacitor 17 is in a standby state.
(S1b) Paper feeding is started at 75 CPM, and the temperature of the fixing roller 1 is maintained at the reload temperature or higher until the end of paper feeding by supplying power from the commercial power supply 16 (voltage 92 V) and the capacitor 17 (discharge starting voltage 43 V). A good copy of the state is possible. Note that 80s is required as the paper passing time.

  As described above, in the configuration which is the premise of the present invention, there is a problem that the image quality is deteriorated when the voltage of the commercial power source is lowered, whereas in the present invention, such a capacitor is used effectively. Even in this case, good image quality can be ensured.

Next, FIG. 5 shows a configuration example in which the fixing device system 10 of the present invention is incorporated in an image forming apparatus.
In the image forming apparatus 100 of FIG. 5, the drum-shaped photosensitive member 101 as an image carrier, charging means 102 for uniformly charging the photosensitive member 101, and laser light L is exposed on the charged photosensitive member 101. The laser optical system 140 that forms an electrostatic latent image and the developing unit 107 that develops the electrostatic latent image on the photoconductor 101 into a toner image constitutes an electrophotographic mechanism. Further, the toner image on the photosensitive member 101 is transferred to the sheet P supplied from the paper feeding cassette 110 by the transfer unit 106, and the sheet P on which the toner image is formed is conveyed to the fixing device system 10 and added to the fixing roll 1. In this configuration, the toner is fixed to the sheet P by being heated by the pressure roll 2.

  In the image forming apparatus 100, when the main power is turned on, each part of the image forming apparatus 100 is activated, and at the same time, the fixing device system 10 is also started up, and supply of power from the capacitor 17 to the heater 4 of the fixing device 10 is started. The fixing roller 1 is heated and enters a standby state. Subsequently, the power supply control of the present invention described above is performed. That is, when the voltage drop of the commercial power supply 16 occurs, the target voltage for charging the capacitor 17 is changed so as to increase, and the capacitor 17 is charged up to the target voltage. Here, when the print command information is input by an external input, power is supplied from the capacitor 17 with a higher capacitor voltage than the normal case so as to compensate for the voltage drop of the commercial power supply 16, and good until the end of continuous paper feeding. Image quality can be obtained.

Hereinafter, a configuration that is a premise of the second embodiment of the image forming apparatus according to the present invention will be described.
FIG. 17 shows an example of a fixing device. The fixing device shown in FIG. 17 differs from the fixing device shown in FIG. 14 in that three heaters 93, 94a, and 94b in total are uniformly arranged inside the hollow cylinder of the fixing roller 91. Otherwise, the configuration is the same as that of FIG.

Here, the heater 93 is a main heater that receives power supply from a commercial power source. For example, the rated power is 1200 W.
The heaters 94a and 94b are sub-heaters that receive power supply from the capacitors. Among these, the heater 94a is used when the apparatus is started up. For example, the rated power is 700 W (at 100 V). Further, the heater 94b is used when a sheet is passed, and has a rated power of 500 W (at 100 V), for example.

  The circuit configuration of the fixing device system including this fixing device is different from the circuit configuration of the fixing device system in FIG. 15 in that the heaters 94a and 94b are connected in parallel so as to be switchable by a capacitor 87 and a switch. Otherwise, the configuration is the same as that of FIG. In this case, the capacitor 87 is of a specification that is charged up to a capacitor voltage of 100V.

An example of the operation of the fixing device system is shown in FIG. In this case, the preconditions are as follows.
-CPM conditions: 75 CPM
・ Capacitor charging target voltage: 100V
・ Voltage of commercial power supply: 100V
・ Capacitor voltage at copy command: 100V
-Heater rated power:
Heater 93: 1200W
Heater 94a: 700W (at 100V)
Heater 94b: 500W (at 100V)
・ Total heater power rating:
(I) At startup: 2400W (all three heaters are turned on, 1200W + 700W + 500W)
(Ii) During continuous paper feeding: 1020 W (heater 93 (main heater), heater 94 b (sub-heater for paper feeding) is turned on, the power input to the heater 93 is 700 W by DUTY control, and the power input to the heater 94 b is raised. (Since the capacitor voltage immediately after becomes 80V, it becomes 320W)

(S91) The capacitor 87 is charged to the target voltage (100V), and enters a discharge standby state.
(S92) When a continuous copy command is issued by the copy start button, the apparatus starts up and power supply from the commercial power source 86 to the heater 93 and from the capacitor 87 to the heaters 94a and 94b is started, and the fixing roller 91 is reloaded. Heated above temperature. Here, all the three heaters are turned on, and the power of 2400 W is turned on, whereby the fixing roller 91 is rapidly heated and started up in 10 seconds.
(S93) Next, paper feeding is started at 75 CPM, and power is supplied from the commercial power source 86 to the heater 93 and from the capacitor 87 to the heater 94b. While the fixing roller 91 is heated by the heat generated by the heaters 93 and 94b, the sheet P carrying the toner T continuously passes through the nip portion between the fixing roller 91 and the pressure roller 92, and fixing is performed. Here, the total input power to the heaters 93 and 94b is 1020W.

  In the above fixing device system, when the voltage of the commercial power source 86 is 100 V, the temperature of the fixing roller 91 is maintained at the reload temperature or higher, and a good copy in the fixing state can be made. In such a case, there is a case where fixing failure occurs even when power is supplied from the commercial power source 86 and the capacitor 87 to the heaters 93 and 94b when the paper is passed. This is the same problem that occurs in the configuration that is the premise of the first embodiment.

  The inventors have obtained the idea of monitoring the voltage of the commercial power supply 86 and intensively studied. As a result, the inventors have achieved the present invention that solves the above problem by efficiently using the capacitor and the heater on the capacitor side.

  The second embodiment of the image forming apparatus according to the present invention will be described below. In addition, embodiment shown below is an illustration and is not limited to this.

  FIG. 6 shows an example of the fixing device. The fixing device shown in FIG. 6 has the same configuration as that of the fixing device shown in FIG. 17, and a total of three heaters 3, 4 a and 4 b are equally arranged inside the hollow cylinder of the fixing roller 1. The heater 3 is a main heater that receives power supply from a commercial power source. For example, the rated power is 1200 W. The heaters 4a and 4b are sub-heaters that receive power supply from the capacitor. The rated power of the heater 4a is, for example, 700 W (at 100 V), and the rated power of the heater 4 b is, for example, 500 W (at 100 V).

  The circuit of the fixing device system according to the present invention can change the total rated power as a heating unit by selecting any one or a plurality of heaters from the circuit configuration of the fixing device system of FIG. The parts are different, and the other parts are the same as in FIG.

FIG. 7 shows a circuit example of a different part of FIG.
The heaters 4a and 4b are connected to the capacitor 17 via the switch unit 1c, and are configured such that one or both of the heaters 4a and 4b can be selected to change the total rated power as the heating unit. Specifically, when the switch sw1 is on and the switch sw2 is off, only the heater 4a is connected to the capacitor 17, and when the switch sw1 is off and the switch sw2 is on, only the heater 4b is connected to the capacitor 17, and the switch sw1 is on and off. When sw 2 is on, the heaters 4 a and 4 b are connected to the capacitor 17.

  FIG. 8 shows a block diagram relating to the total rated power change based on the voltage drop of the commercial power supply in the present invention. In FIG. 8, the CPU 11 is configured to include an information analysis unit Dd, a determination unit 11c, a total rated power setting unit 11f, and a control execution unit Ca that functionally configures a charge / discharge control unit 11A.

  The information analysis unit Dd takes in the voltage information of the commercial power supply 16 detected by the voltage detection unit 1b.

  The determination unit 11c has a function of determining the presence or absence of a voltage drop from the acquired voltage information of the commercial power supply 16. Here, the determination unit 11c has a threshold value (commercial power supply voltage threshold value) for determining whether or not the commercial power supply 16 has a voltage drop. For example, assuming that the threshold value is 93V, it is determined that there is no voltage drop if the voltage information of the commercial power supply 16 is 93V or more, and it is determined that there is a voltage drop if the voltage information is less than 93V.

  The total rated power setting unit 11 f has a function of setting the total rated power to be set as the heating unit based on the determination result of the determination unit 11 c regarding the voltage drop of the commercial power supply 16. Specifically, the combination of the heaters 3, 4 a, 4 b at the time of passing paper is determined based on the determination result. In the case of the determination result without voltage drop of the commercial power supply 16, the combination of the normal heaters, that is, the heater 3 ( A combination of a main heater) and a heater 4b (sub-heater for paper passing). Further, in the case of the determination result that there is a voltage drop of the commercial power supply 16, the heater combination is selected so as to increase the total rated power over the heater combination in the case where the commercial power supply 16 voltage is not lowered. ) And the heater 4a (startup sub-heater). Or the combination which lights all the heaters 3, 4a, 4b may be sufficient.

  The charge / discharge control unit 11A has a function of performing on / off control of the switch unit 1c based on the setting result of the total rated power setting unit 11f and selecting a heater to be connected to the capacitor 17 from the heaters 4a and 4b.

The operation of the fixing device system is as follows. In this case, the preconditions are as follows.
-CPM conditions: 75 CPM
・ Capacitor charging target voltage: 100V
・ Voltage drop of commercial power supply: 100V to 92V ・ Capacitor voltage at the time of copy command: 100V
-Heater rated power:
Heater 3: 1200W
Heater 4a: 700W (at 100V)
Heater 4b: 500W (at 100V)
・ Total heater power rating:
(I) At startup: 2400W (all three heaters are turned on, 1200W + 700W + 500W)
(ii) During continuous paper feeding:
When commercial power supply voltage ≧ 93 V, 1020 W (heater 3 (main heater), heater 4 b (paper sub-heater) lights up)
For commercial power supply voltage <93V, 1150W (heater 3 (main heater), heater 4a (startup sub-heater) lights up)

(S21) When a continuous copy command is issued by the copy start button, the voltage detection information (92V) of the commercial power supply 16 detected by the voltage detection unit 1b is taken into the determination unit 11c via the information analysis unit Dd in the CPU 11. It is.
(S22) Since the voltage detection information (92V) is less than the commercial power supply voltage threshold (93V), the determination unit 11c determines that the commercial power supply 16 has a voltage drop.
(S23) A combination of the heater 3 (main heater) and the heater 4a (start-up sub-heater) as the total rated power when the paper is passed by the total rated power setting unit 11f based on the determination result (with voltage drop) of the determination unit 11c Select.
(S24) The apparatus starts up, and power supply from the commercial power supply 16 to the heater 3 and from the capacitor 17 to the heaters 4a and 4b is started, and the fixing roller 1 is heated to the reload temperature or higher. Here, all three heaters are turned on, and the power of 2400 W is turned on, whereby the fixing roller 1 is rapidly heated and started up in 10 seconds.
(S25) Next, paper feeding is started at 75 CPM, and power is supplied from the commercial power source 16 to the heater 3 and from the capacitor 17 to the heater 4a. Here, the total input power to the heaters 3 and 4a is 1150W. As a result, the temperature of the fixing roller 1 is maintained at the reload temperature or higher until the end of the sheet passing, and a copy in a fixed state can be made.

  As described above, the configuration that is the premise of the present invention has a problem that the image quality is deteriorated when the voltage of the commercial power supply is lowered, whereas the present invention efficiently uses the capacitor and the heater on the capacitor side. In such a case, good image quality can be ensured.

Further, in the above configuration, the total rated power for passing paper is set from a heater combination in which one of the two heaters on the capacitor side is selected. A plurality of heaters constituting the heating unit as follows It may be set from a heater combination that selects any one or a plurality of heaters.
(Combination 1) Combination of heater 4a (startup heater) and heater 4b (sub-heater for paper passage) (Combination 2) Combination of heater 3 (main heater) and heater 4b (sub-heater for paper passage) (Combination 3) Combination of heater 3 (main heater) and heater 4a (start-up sub-heater) (combination 4) Combination of heater 3 (main heater), heater 4a (start-up sub-heater) and heater 4b (sheet-passing sub-heater)

  The configuration example in which the fixing device system of the present embodiment is incorporated in the image forming apparatus is basically the same as that shown in FIG. 5 and detailed description is omitted, but the image forming apparatus 100 of the present example is external. When the print command information is input by input, the total rated power at the time of continuous paper feeding of the heater as the heating unit is set by the voltage of the commercial power supply 16 detected. When the voltage drop of the commercial power supply 16 is detected, the heating part is changed so that the total rated power becomes higher than usual. As a result, the amount of heat generated by the heater on the capacitor 17 side is increased so as to compensate for the voltage drop of the commercial power supply 16, and good image quality can be obtained up to the end of continuous paper feeding.

  The third embodiment of the image forming apparatus according to the present invention will be described below. In addition, embodiment shown below is an illustration and is not limited to this.

FIG. 9 is a cross-sectional view showing the configuration of the fixing device according to the present invention.
The fixing device shown in FIG. 9 is in contact with the fixing roller 1 heated by the heating unit including the heaters 3 and 4, the pressure roller 2 that presses the fixing roller 1 with a constant nip pressure, and the surface temperature of the fixing roller 1. And temperature detecting means 5 for detecting.

  The fixing roller 1 is usually a hollow cylindrical roller, but may be in the form of an endless belt. Further, the fixing device 10 is stationary when the sheet rises, and rotates clockwise in the drawing when the sheet is passed.

  The pressure roller 2 is usually a cylindrical roller whose surface is made of an elastic member such as silicone rubber, but may be in the form of an endless belt. The pressing roller 2 is pressed against the fixing roller 1 by being pressed in the direction of the fixing roller 1 with a constant pressure by a pressing means (not shown). The pressure roller 2 is also stationary when the fixing device rises, and rotates counterclockwise in the figure when the sheet is passed. The rotation driving of the fixing roller 1 and the pressure roller 2 is performed by a driving mechanism (not shown).

  The temperature detecting means 5 is disposed on the opposite side of the nip portion with the central axis of the fixing roller 1 as the temperature detection position. In addition, any thermometer that can detect the surface temperature of the fixing roller 1 may be a contact thermometer, a non-contact thermometer, a thermocouple, or the like.

The heaters 3 and 4 are rod-shaped heaters which are one embodiment of the heating element, and the cross-sectional shape is shown in the drawing.
The heater 3 generates heat when power is supplied from an external power source such as a commercial power source that can always supply power, and heats the fixing roller 1 by the radiant heat.
The heater 4 generates heat when power is supplied from a capacitor which is an aspect of the battery, and the fixing roller 1 is heated by the radiant heat. The heater 4 is maintained at an appropriate fixing roller temperature by power control means such as on / off control. Yes.

FIG. 10 is a circuit diagram of the fixing device system according to the present invention.
In the fixing device system 30, the heater 3 generates heat by electric power supplied from an external power supply (commercial power supply) 16, and the heater 4 generates heat by electric power supplied from a capacitor 37 that is one mode of the power storage unit. . The heater 4 is preferably one in which a plurality of heaters are connected in parallel with the capacitor 37, and any one or all of these heaters may be connected to the capacitor 37 by switching a switch (not shown). For example, all heaters are connected to the capacitor 37 when the apparatus is started up, and any selected heater is connected when paper is passed.

  The fixing device system 30 includes a power storage detector 18 that detects a capacitor voltage that is an index of the stored energy (remaining power amount) of the capacitor 37, and a voltage detector 1 b that detects the voltage of the commercial power supply 16. The capacitor voltage, the commercial power supply voltage, and the temperature of the fixing roller 1 are input to the CPU 31 which is one mode of the control unit through the input circuit as detection signals. Further, the CPU 31 supplies power to the heater 3 via the triac 13 and to the heater 4 via the FET 15 so that the surface temperature of the fixing roller 1 becomes a set temperature based on detection signals from the power storage detector 18 and the temperature sensor 15. Are controlled by the controllers 12 and 14, respectively. The capacitor 37 is connected to the charging device 1a and can be charged by switching the switch 19 under the control of the CPU 31.

  The capacitor 37 is preferably a capacitor having a large capacitance such as an electric double layer capacitor having a capacitance greater than or equal to the Farad order, and the cell capacitance of the capacitor 37 is particularly preferably 500 F or more.

  FIG. 11 is a block diagram relating to the target voltage change based on the voltage drop of the commercial power supply in the present invention. In FIG. 11, the CPU 31 is configured to include an information analysis unit Dd and a control execution unit Ca that functionally configures the determination unit 31 c and the charge / discharge control unit 31 </ b> A.

  The information analysis unit Dd captures capacitor voltage information of the capacitor 37 detected by the power storage detector 18.

  The determination unit 31 c has a function of determining whether or not the capacitor 37 has reached a target voltage to be charged from the capacitor voltage information of the capacitor 37. Here, the determination unit 31c has a threshold value (target voltage threshold value) for the determination. This threshold is preferably 80% of the rated cell voltage constituting the capacitor 37.

  The charge / discharge control unit 31 </ b> A has a function of controlling the charging of the capacitor 37 by switching the switch 19 based on the determination result of the determination unit 31 c regarding the capacitor voltage of the capacitor 37. Specifically, if the capacitor voltage of the capacitor 37 is equal to or higher than the target voltage, the switch 19 is switched to the heater 4 side to place the capacitor 37 in a discharge standby state. If the capacitor voltage is lower than the target voltage, the switch 19 is set to the charging device 1a side. To charge the capacitor 37.

An example of the operation of the fixing device system of the present invention will be described below. In this case, the preconditions are as follows.
・ Capacitor 37 specification: Electric double layer capacitor ・ Cell specification: Cell capacity 500F, Cell rated voltage 2.5V
・ ・ Bank configuration with 20 cells ・ Target voltage threshold: 40V
Initial capacitor voltage: 35V

(S31) Capacitor voltage detection information (35V) of the capacitor 37 detected by the power storage detector 18 is taken into the determination unit 31c via the information analysis unit Dd in the CPU 31.
(S32) The determination unit 31c determines that the capacitor voltage detection information (35V) is less than the target voltage (40V).
(S33) Based on the determination result (less than the target voltage) of the determination unit 31c, the charge / discharge control unit 31A switches the switch 19 to the charging device 1a side, and charging of the capacitor 37 is started.
(S34) The capacitor voltage of the capacitor 37 reaches 40V, and the capacitor voltage detection information (40V) detected by the power storage detector 18 is taken into the determination unit 31c via the information analysis unit Dd in the CPU 31.
(S35) The determination unit 31c determines that the capacitor voltage detection information (40V) is equal to or higher than the target voltage (40V).
(S36) Based on the determination result (more than the target voltage) of the determination unit 31c, the charge / discharge control unit 31A switches the switch 19 to the heater 4 side, and the capacitor 37 enters the discharge standby state.

  When a continuous copy command is issued by the copy start button after the capacitor 37 in step s36 is in a discharge standby state, power is supplied from the commercial power supply 16 to the heater 3 when the apparatus is started up and / or during continuous paper feeding. At the same time, electric power is supplied from the capacitor 37 to the heater 4 so that the fixing roller 1 is heated to a temperature higher than the reload temperature. In addition, since the capacitor 37 has a voltage lower than the target voltage after this discharge, the charging operation in steps s31 to s36 is performed again when the apparatus is on standby.

Next, FIG. 12 shows a configuration example in which the fixing device system 30 of this embodiment is incorporated in an image forming apparatus.
In the image forming apparatus 100 shown in FIG. 12, the drum-shaped photosensitive member 101 as an image carrier, charging means 102 for uniformly charging the photosensitive member 101, and laser light L is exposed on the charged photosensitive member 101. The laser optical system 140 that forms an electrostatic latent image and the developing unit 107 that develops the electrostatic latent image on the photoconductor 101 into a toner image constitutes an electrophotographic mechanism. Further, the toner image on the photosensitive member 101 is transferred to the sheet P supplied from the paper feeding cassette 110 by the transfer unit 106, and the sheet P on which the toner image is formed is conveyed to the fixing device system 30 and added to the fixing roll 1. In this configuration, the toner is fixed to the sheet P by being heated by the pressure roll 2.

  In the image forming apparatus 100, when the main power is turned on, each part of the image forming apparatus 100 is activated, and at the same time, the fixing device system 30 enters a start-up operation. Supply of electric power is started, the fixing roller 1 is heated, and enters a standby state. Next, the capacitor 37 is charged to the target voltage under the control of the CPU 31. Here, when print command information is input by external input, power is supplied to the heaters 3 and 4 from the commercial power supply 16 and the capacitor 37, respectively, and good image quality can be obtained up to the end of continuous paper feeding. Furthermore, the life of the capacitor 37 can be extended even if such charging and discharging are repeated.

  Examples of the image forming apparatus according to the third embodiment will be described below. Here, the grounds that the cell capacity of the capacitor 37 is 500 F or more and the target voltage is 80% or more of the cell rated voltage are shown.

  FIG. 13 is a conceptual diagram showing the relationship between the endurance years and the cell voltages of cells having a cell capacity of 300F and 500F constituting the capacitor. The cell constituting the capacitor has a tendency that the higher the cell voltage to be charged, the faster the cell is deteriorated and the shorter the endurance time that is the life of the cell, and the lower the cell voltage, the longer the endurance time.

In the image forming apparatus, the capacitor needs to have a certain level of durability. Assuming that the endurance time is Y ₁ , in order to satisfy the endurance time Y ₁ in FIG. 13, the cell voltage needs to be 2.0 V or less in the 300 F cell, and the cell voltage is 2.5 V or less in the 500 F cell It is understood that it is necessary to.

On the other hand, it is preferable that the electric power supplied to the heater for heating the fixing roller 1 in the image forming apparatus is as large as possible. However, the maximum current value that can be supplied by the capacitor 37 that supplies electric power to the heater 4 is determined. Higher is preferable.
Here, for example, if the required capacitor voltage is 50V, a capacitor can be configured with 20 cells if the cell voltage is 2.5V, but 25 cells are required if the cell voltage is 2.0V. As a result, the size and weight are increased, and the cost is further disadvantageous. On the other hand, in a capacitor composed of 20 cells, the power supplied to the heater 4 is insufficient at a cell voltage of 2.0 V, so that the temperature of the fixing roller 1 is lowered and a problem occurs in the fixability.

Table 1 shows the results of experiments using the image forming apparatus shown in FIG. 12 based on the relationship between the cell capacity and the cell voltage in the above capacitor. The experimental conditions were as follows.
(1) Capacitor 37 specification: Electric double layer capacitor 20 bank configuration Cell specification: Cell rated voltage 2.5V
Cell capacity: 2 levels of 300,500F (2) Target voltage threshold: 2 levels of 30V, 40V (60% and 80% of cell rated voltage) for cell capacity of 300F.
In the case of a cell capacity of 500 F, one level of 40 V (80% of the cell rated voltage).
(3) Evaluation Items / Fixability: An image was formed on a storage medium by an image forming apparatus, the fixing state of the image was evaluated, and a determination was made based on good fixing (symbol o) and poor fixing (symbol x).
Life: Image formation in which the capacitor 37 is charged and discharged in the image forming apparatus was repeatedly performed, and the deterioration state of the capacitor 37 was evaluated. When capacitor deterioration was not recognized, the evaluation was good (symbol ○), and when capacitor deterioration was observed, the evaluation was poor (symbol x).

  As described above, when the cell capacity of the capacitor 37 is set to 500 F or more and the target voltage is set to 80% or more of the cell rated voltage, good fixability can be secured and the life of the capacitor can be extended.

1 is a cross-sectional view of a fixing device according to a first embodiment of the present invention. 1 is a circuit diagram of a fixing device system according to a first embodiment of the present invention. 1 is a block diagram of a fixing device system according to a first embodiment of the present invention. 2 is an operation example of the fixing device system according to the first embodiment of the present invention. 1 is a cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. It is sectional drawing of the fixing device in the 2nd Embodiment of this invention. It is a figure which shows the principal part among the circuits of the fixing device system in the 2nd Embodiment of this invention. FIG. 6 is a block diagram of a fixing device system according to a second embodiment of the present invention. FIG. 9 is a cross-sectional view of a fixing device according to a third embodiment of the present invention. FIG. 10 is a circuit diagram of a fixing device system according to a third embodiment of the present invention. FIG. 10 is a block diagram of a fixing device system according to a third embodiment of the present invention. It is sectional drawing of the image forming apparatus of the 3rd Embodiment of this invention. It is a conceptual diagram which shows the relationship between the durable years and cell voltage of each of the cell whose cell capacity is 300F and 500F which comprise a capacitor. 1 is a cross-sectional view of a fixing device which is a premise of a first embodiment. 1 is a circuit configuration example of a fixing device system which is a premise of a first embodiment. 2 is an operation example of a fixing device system that is a premise of the first exemplary embodiment. FIG. 6 is a cross-sectional view of a fixing device which is a premise of a second embodiment. 7 is an operation example of a fixing device system which is a premise of the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,91 Fixing roller 2,92 Pressure roller 3,4,4a, 4b, 93,94,94a, 94b Heater 5,95 Temperature detection means 10,30,90 Fixing device system 11,31 CPU
11c, 31c determination unit 11e target voltage setting unit 11f total rated power setting unit 11A, 31A charge / discharge control unit Ca control execution unit Dd information analysis unit 12, 14, 82, 84 controller 13, 83 triac 15, 85 FET
16, 86 Commercial power supply 17, 37, 87 Capacitor 18, 88 Power storage detector 19, 89, sw1, sw2 Switch 1a, 8a Charging device 1b Image reading unit 1c Switch unit 100 Image forming device 101 Photoconductor 102 Charging unit 103 Cleaning unit 105 Developing sleeve 106 Transfer means 107 Developing section 110 Paper cassette 111 Middle plate 112 Arm 113 Paper feed roller 114 Separating pad 115 Registration roller pair 120 Paper discharge roller pair 121 Paper discharge port 122 Paper discharge tray 125 Paper discharge auxiliary tray 130 Operation panel 131 Exterior part 132 Paper feed tray 133 Pin 134 Case 135 Power supply circuit 136 Print board 137 Controller board 140 Laser optical system P Sheet T Toner

Claims (4)

A storage battery that is charged by a commercial power supply; a heating unit that is supplied with power from the commercial power supply and the storage battery; and a fixing member that is heated by the heating unit. In the image forming apparatus for fixing the unfixed image to
A voltage detector for detecting the voltage of the commercial power supply;
A controller that charges the battery with the commercial power supply until the voltage of the battery is equal to or higher than a target voltage;
The image forming apparatus, wherein the control unit changes the target voltage to be higher when a detection voltage of the voltage detection unit is lowered. A storage battery that is charged by a commercial power supply; a heating unit that is supplied with power from the commercial power supply and the storage battery; and a fixing member that is heated by the heating unit. In the image forming apparatus for fixing the unfixed image to
A voltage detector for detecting the voltage of the commercial power supply;
A control unit for changing the total rated power of the heating unit,
The image forming apparatus, wherein the control unit increases a total rated power of the heating unit when a detection voltage of the voltage detection unit decreases.   The image forming apparatus according to claim 2, wherein the heating unit includes a plurality of heaters, and the control unit selects one or more of the heaters to change the total rated power of the heating unit. A storage battery that is charged by a commercial power supply; a heating unit that is supplied with power from the commercial power supply and the storage battery; and a fixing member that is heated by the heating unit. In the image forming apparatus for fixing the unfixed image to
A controller that charges the battery with the commercial power supply until the voltage of the battery is equal to or higher than a target voltage;
The image forming apparatus, wherein a cell capacity of the capacitor is 500 F or more, and the target voltage is 80% or more of a cell rated voltage.

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