JP4366202B2 - Image forming apparatus - Google Patents

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, but is started up when the main power is turned on from the state where the fixing apparatus 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, since the image forming apparatus is configured so as to give top priority to ensuring image quality, it may take a lot of copying time to lower the sheet passing speed than usual for the purpose of preventing fixing failure. In some cases, it was difficult to shorten the total copying time.

  The present invention has been made in view of the above-described problems in the prior art. By improving the utilization efficiency of the battery, the startup time is shortened, the copying speed is increased, and the total copying time is shortened. It is an object of the present invention to provide an image forming apparatus that can be used.

The present invention provided to solve the above problems includes a capacitor charged by a commercial power source, a heating unit supplied with power from the commercial power source and the capacitor, a fixing member heated by the heating unit, and the capacitor In an image forming apparatus that includes a power storage detection unit that detects a voltage value , heats an unfixed image by the fixing member, and fixes the unfixed image on a recording medium, a plurality of recording media are continuously connected to the fixing member. And a sheet number predicting unit that predicts the total number of recording media that pass through the fixing member during continuous sheet passing, and a total number of sheets less than a predetermined number based on the total number of sheets predicted by the sheet number predicting unit . threshold and the total number of 1 is set to one threshold value of the second threshold value larger than the first threshold value in the case of more than a predetermined number, the voltage value of the capacitor of the power storage detecting unit detects said Set If less than the threshold value, as well as allow the starting power supply to the heating unit from the accumulator, the image forming processing number per unit of time when the power to the heating unit of the image forming processing number per unit time from the accumulator is not supplied And an image forming apparatus including a control unit that sets a larger value .

  Here, it is preferable that an image reading unit for reading an image is provided, and the number predicting unit predicts the total number of sheets based on document reading information of the image reading unit.

  Further, it is preferable that the number prediction unit predicts the total number of sheets based on print command information input from outside.

  According to the present invention, even if the stored energy of the battery does not reach the threshold value in the conventional case, if the stored energy is sufficient for the total number of sheets to be passed, the threshold value is reliably reduced and set. Thus, it is possible to supply the power of the storage battery, improve the utilization efficiency of the storage battery, and provide an image forming apparatus that is easy to use for a user whose startup time is fast and copying speed is fast.

Hereinafter, a configuration that is a premise of the embodiment of the present invention will be described.
FIG. 5 shows an example of a fixing device. The fixing device shown in FIG. 5 is heated by heaters 93, 94a, and 94b, which are an embodiment of the heating unit, and rotates in the clockwise direction in the figure, and holds the fixing roller 91 with a constant nip pressure and counterclockwise in the figure. A pressure roller 92 that rotates in the rotation direction and a temperature detection means 95 that contacts the fixing roller 91 and detects the surface temperature thereof are provided.

  The fixing roller 91 is usually a hollow cylindrical roller, but may be an endless belt. In addition, the fixing device is stationary when the fixing device rises, and rotates in the clockwise direction in the drawing when the sheet P as a recording medium is passed.

  The pressure roller 92 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 92 is pressed against the fixing roller 91 by being pressed in the direction of the fixing roller 91 with a constant pressure by a pressing means (not shown). The pressure roller 92 is also stationary when the fixing device rises, and rotates counterclockwise in the drawing when the sheet P as a recording medium is passed. The rotation driving of the fixing roller 91 and the pressure roller 92 is performed by a driving mechanism (not shown).

  The heaters 93, 94a, and 94b are all disposed in the hollow portion of the fixing roller 91. However, the heaters 93, 94a, and 94b may be disposed so as to cover the upper portion of the fixing roller 91 as sheet heaters.

The heater 93 generates heat when power is supplied from an external power source such as a commercial power source, and heats the fixing roller 91 by the radiant heat.
The heaters 94a and 94b generate heat when electric power is supplied from the capacitor, and heat the fixing roller 91 by the radiant heat.
The heaters 93, 94 a, and 94 b generate heat when supplied with electric power and can heat the fixing roller 91, and there are no particular restrictions on the type of heater, and the heaters 93, 94 a, and 94 b can be arranged at any position where the fixing roller 91 is heated. It is.

  The temperature detecting means 95 may be any one of a contact thermometer and a non-contact thermometer as long as it can detect the surface temperature of the fixing roller 91, such as a radiation thermometer or a thermocouple.

  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. 6 shows a circuit configuration example of the fixing device system. In FIG. 6, a heater 93 generates heat by electric power supplied from an external power supply (commercial power supply) 86, and a heater 94 including heaters 94a and 94b generates heat by electric power supplied from a capacitor 87 which is one mode of a power storage unit. It has become. 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.

As the capacitor 87, it is preferable to use a capacitor having a large capacitance such as an electric double layer capacitor whose capacitance is equal to or greater than the Farad order.
The capacitor 87 is connected with a power storage detector 88.

  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 the 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.

  A block diagram relating to mode selection based on capacitor voltage in the system is shown in FIG. In FIG. 7, the CPU 81 includes a determination unit 81a and a mode selection unit 81b. The determination unit 81a has a preset threshold value related to the capacitor voltage at the time of paper passing (discharge start threshold value), and the mode selection unit 81b transfers the capacitor 87 from the capacitor 87 to the heater 94 when the apparatus is started up and during the paper passing operation. It has a plurality of modes such as permission / non-permission of power supply and setting of CPM (number of copies per minute) according to permission / non-permission of power supply from the capacitor 87.

In FIG. 7, mode selection is performed as follows, for example.
(S81) A continuous copy command is issued by the copy start button.
(S82) The capacitor voltage of the capacitor 87 is detected by the power storage detection unit 88, and the detection signal is captured by the CPU 81.
(S83) In the determination unit 81a in the CPU 81, the detected capacitor voltage is compared with the threshold value, the magnitude is determined, and the determination result is sent to the mode selection unit 81b.
(S84) The mode selection unit 81b performs mode selection according to the determination result of step s93, and the operation of the image forming apparatus including the fixing device system is controlled based on the selected mode.

For example, the following modes are prepared as the mode selected in step s94.
(Mode 91) When the detected capacitor voltage is equal to or higher than the threshold, power supply from the capacitor 87 to the heater 94 at the time of passing paper is permitted, and CPM is set as a normal condition.
(Mode 92) When the detected capacitor voltage is less than the threshold value, the power supply from the capacitor 87 to the heater 94 during passage of paper is not permitted, and the CPM is reduced (down). In this case, it is impossible to supply power enough to compensate for the temperature drop of the fixing roller 91 due to continuous paper passing, and fixing failure occurs under normal conditions of the CPM. Therefore, the CPM is lowered to ensure image quality. is there.

FIG. 8 shows an operation example of the fixing device system when the detected capacitor voltage is less than the threshold value. In this case, the preconditions are as follows.
・ Threshold (when paper is passed): 30V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM
・ Copy command: 40 sheets continuously passed ・ Capacitor voltage at copy command: 27V

(S91) When a continuous copy command is issued by the copy start button, the capacitor voltage (27V) of the capacitor 87 is detected by the power storage detection unit 88, and the detection signal is captured by the CPU 81.
(S92) In the determination unit 81a, it is determined that the capacitor voltage (27V) is less than the threshold value (30V), and the determination result is sent to the mode selection unit 81b.
(S93) In the mode selection unit 81b, power supply from the capacitor 87 to the heater 94 during paper passing is not permitted, and the mode (mode 92) of the CPM down condition (40 CPM) is selected.
(S94) Power supply from the commercial power supply 86 to the heater 94 is started, the fixing roller 91 is heated, and 30s is required as a startup time. At this time, the capacitor 87 is in a standby state.
(S95) The sheet feeding is started at 40 CPM, and the temperature of the fixing roller 91 is maintained only by the commercial power source 86, and a good copy in the fixing state is possible. At this time, the capacitor 87 is in a standby state. In addition, 60 s is required as a paper passing time. That is, the total copying time is 90 seconds.

As described above, even when the number of continuous paper passes is relatively small and the temperature drop of the fixing roller is slight, if the charging voltage of the capacitor is less than the threshold value, the paper passing speed is lowered and the stored power of the capacitor is reduced. The image was formed without using the printer, and copying took time.
The inventors have found that this problem occurs because the threshold value of the charging voltage is set so as not to cause a temperature drop regardless of the number of continuous sheets to be passed and the type of paper according to the specifications of the copying machine. As a result of careful attention and intensive studies, the present invention has been achieved to solve the above problems by efficiently utilizing capacitors.

  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. 1 is a circuit diagram of a fixing device system according to the present invention.
The fixing device system 10 is the same as the configuration of FIG. 6 except for the CPU 11 in the configuration that is the premise of the embodiment of the present invention illustrated in FIG. 6, and the commercial power source 16 connected to the heater 93. , The capacitor 17 connected to the heater 94 composed of the heaters 94 a and 94 b, the power storage detector 18 connected to the capacitor 17, the controller 12 for controlling the power supply of the commercial power supply 16, the triac 13, and the power supply control of the capacitor 17. The controller 14, the FET 15, the switch 19, and the charging device 1a. Further, the fixing device may be configured as shown in FIG.

  The CPU 11 has a number prediction unit 11a and is connected so as to be able to take in information from the image reading unit 1b and the external input unit 1c. Further, the CPU 11 uses the capacitor voltage that is an index of the stored energy (remaining power amount) of the capacitor 17 detected by the storage detector 18 and the temperature of the fixing roller 91 detected by the temperature detecting means 95 as detection signals. take in.

  A block diagram relating to mode selection based on the capacitor voltage in the present invention is shown in FIG. In FIG. 2, the CPU 81 includes a number prediction unit 11 a, a threshold setting unit 11 b, a determination unit 11 c, and a mode selection unit 11 d.

  The sheet number predicting unit 11a predicts the total number of sheets that are continuously passed through the fixing device during continuous sheet passing. For example, the total number of sheets may be a value obtained by multiplying the number-of-originals information obtained at the time of image reading from the image reading unit 1a and the number-of-copying information input at the time of a copy command. Further, the total number may be obtained from the number of documents included in the print command information input from the external input unit 1c and the number of printouts.

  The threshold value setting unit 11b has a function of setting a threshold value related to the capacitor voltage during sheet passing based on the total number information from the sheet number prediction unit 11a.

Specifically, the total number of sheets is divided by a certain range, and a threshold value is set for each range, so that the total number information from the number prediction unit 11a is set to the threshold value of the corresponding range. For example, when the total number n is equal to or greater than the conventional threshold value, the threshold value may be a value lower than the conventional threshold value when the total number is less than n. Alternatively, to calculate the sheet passing time t ₁ when the first continuously printed by the total number information from the CPM normal conditions, then assuming the state power supplied to the heater 94 from the capacitor 17 during continuous paper feed, the capacitor 17 is discharged which is the lower limit of the possible voltage is calculated back from the capacitor lower limit voltage in the form dating back only paper passing time t ₁ seeking capacitor voltage may be the value as a threshold value.

  Next, the set threshold information is sent to the determination unit 11c.

  The determination unit 11c has a function of comparing the threshold value set from the threshold value setting unit 11b with the detected capacitor voltage and determining the magnitude thereof.

  The mode selection unit 11d permits or prohibits power supply from the capacitor 17 to the heater 94 at the time of starting the apparatus and during paper feeding operation, and CPM (per minute) according to permission or non-permission of power supply from the capacitor 17 Have multiple modes, such as the number of copies.

In FIG. 2, mode selection is performed as follows, for example.
(S11) A continuous copy command is issued by the copy start button.
(S12) The capacitor voltage of the capacitor 17 is detected by the power storage detection unit 18, and the detection signal is captured by the CPU 11.
(S13) In the sheet number predicting unit 11a, the total number of sheets is obtained by multiplying the number-of-documents information fetched from the image reading unit 1a and the number-of-copying information inputted at the time of the copy command.
(S14) In the threshold setting unit 11b, the predetermined threshold is set as described above, and the information is sent to the determination unit 11c.
(S15) In the determination unit 11c, the detected capacitor voltage is compared with the threshold value set from the threshold value setting unit 11b, the size is determined, and the determination result is sent to the mode selection unit 11d.
(S16) The mode selection unit 11d performs mode selection according to the determination result of step s15, and the operation of the image forming apparatus including the fixing device system is controlled based on the selected mode.

For example, the following modes are prepared as the mode selected in step s16.
(Mode 1) When the detected capacitor voltage is equal to or higher than the set threshold value, power supply is permitted from the capacitor 17 to the heater 94 when paper is passed, and CPM is set as a normal condition.
(Mode 2) When the detected capacitor voltage is less than the set threshold value, power supply from the capacitor 17 to the heater 94 at the time of passing paper is not permitted, and CPM is set as a down condition.

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.
・ Threshold (when paper is passed);
Threshold value A = 30V when the number of continuous sheets passed ≧ 50
When the number of continuous paper passes <50, the threshold B = 25V
-CPM normal conditions: 75 CPM
-CPM down condition: 40 CPM
・ Copy command: 40 sheets continuously passed ・ Capacitor voltage at copy command: 27V

(S21) When a continuous copy command is issued by the copy start button, the capacitor voltage (27V) of the capacitor 17 is detected by the power storage detector 18, and the detection signal is captured by the CPU 11.
(S22) In the sheet number predicting unit 11a, the total number of sheets (40 sheets) is obtained by multiplying the document sheet number information fetched from the image reading unit 1a and the copy sheet number information input at the time of the copy command.
(S23) In the threshold setting unit 11b, a threshold B (25V) is set based on the total number information (40 sheets) from the number prediction unit 11a, and the information is sent to the determination unit 11c.
(S24) In the determination unit 11c, it is determined that the detected capacitor voltage (27V) is equal to or higher than the threshold value B (25V), and the determination result is sent to the mode selection unit 11d.
(S25) In the mode selection unit 11d, the mode 1 is selected.
(S26) When the apparatus is started up, power supply from the commercial power supply 16 to the heater 94 is started, the fixing roller 91 is heated, and it takes 30 s as a start-up time. At this time, the capacitor 17 is in a standby state.
(S27) Paper feeding is started at 75 CPM, the temperature of the fixing roller 91 is maintained by the power supplied from the commercial power supply 16 and the capacitor 17, and a good copy in the fixing state is possible. Note that 32 s is required as the paper passing time.

  As described above, the total copying time, which took 90 seconds in the configuration as a premise of the present invention, can be shortened to 62 seconds in the present invention.

Next, FIG. 4 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. 4, the drum-shaped photoconductor 101 as an image carrier, charging means 102 for uniformly charging the photoconductor 101, and laser light L is exposed on the charged photoconductor 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. In addition, 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 91. The toner is fixed to the sheet P by being heated by the pressure roll 92.

  In the image forming apparatus 100, when the main power is turned on, each part of the image forming apparatus 100 is started, and at the same time, the fixing device system 10 also starts up, and supply of power from the capacitor 17 to the heater 94 of the fixing device is started. The fixing roller 91 is heated and enters a standby state. Then, when print command information is input by external input, the power supply control of the present invention described above is performed. That is, even if the stored energy of the capacitor does not reach the threshold in the conventional case, if the stored energy is sufficient for the total number of sheets to be passed, the capacitor can be reliably set by setting the threshold to a reduced value. Therefore, it is possible to improve the use efficiency of the capacitor, to make the image forming apparatus easy to use for the user whose startup time is fast and the copying speed is fast.

1 is a circuit diagram of a fixing device system according to the present invention. It is a block diagram regarding mode selection based on a capacitor voltage in the present invention. It is an example of operation | movement of the fixing device system of this invention when the detected capacitor voltage is less than a threshold value. 1 is a cross-sectional view of an image forming apparatus of the present invention. FIG. 3 is a cross-sectional view of a fixing device. 2 is a circuit configuration example of a fixing device system. FIG. 7 is a block diagram relating to mode selection based on capacitor voltage in the system of FIG. 6. 7 is an operation example of the fixing device system in FIG. 6 when the detected capacitor voltage is less than a threshold value.

Explanation of symbols

1a, 8a Charging device 1b Image reading unit 1c External input unit 10,90 Fixing device system 11 CPU
11a Number prediction unit 11b Threshold setting unit 11c, 81a Judgment unit 11d, 81b Mode selection unit 12, 14, 82, 84 Controller 13, 83 Triac 15, 85 FET
16, 86 Commercial power supply 17, 87 Capacitor 18, 88 Power storage detector 19, 89 Switch 91 Fixing roller 92 Pressure roller 93, 94, 94a, 94b Heater 95 Temperature detection means 100 Image forming apparatus 101 Photoconductor 102 Charging means 103 Cleaning Means 105 Developing sleeve 106 Transfer means 107 Developing section 110 Paper feed 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 portion 132 Paper feed tray 133 Pin 134 Case 135 Power supply circuit 136 Printed board 137 Controller board 140 Laser optical system P sheet T toner

Claims (3)

A storage battery charged by a commercial power supply; a heating unit powered by the commercial power supply and the storage battery; a fixing member heated by the heating unit; and a storage battery detection unit for detecting a voltage value of the storage battery, In an image forming apparatus that heats an unfixed image by a fixing member and fixes the unfixed image on a recording medium,
A number predicting unit that predicts the total number of recording media that pass through the fixing member when a plurality of recording media continuously pass through the fixing member;
Based on the total number predicted by the number prediction unit, a first threshold value when the total number is less than a predetermined number and a second threshold value greater than the first threshold when the total number is equal to or more than a predetermined number When one of the threshold values is set and the voltage value of the capacitor detected by the power storage detection unit is equal to or higher than the set threshold value, the power supply from the capacitor to the heating unit is permitted to start and the unit time per unit time An image forming apparatus comprising: a control unit that sets the number of image forming processes to be larger than the number of image forming processes per unit time when power is not supplied from the capacitor to the heating unit . It has an image reading unit that reads images,
The image forming apparatus according to claim 1, wherein the number prediction unit predicts the total number based on document reading information of the image reading unit.   The image forming apparatus according to claim 1, wherein the number prediction unit predicts the total number based on print command information input from outside.

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