JP4823819B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

Patent Document 1 discloses a fixing device including a pair of fixing rollers, a main power supply device, an auxiliary power supply device, and control means. The pair of fixing rollers are arranged so as to face each other in a state where their peripheral surfaces are in close contact with each other, and a main heating unit and an auxiliary heating unit are incorporated in one of the fixing rollers. The main power supply device supplies power to the main heating unit. The auxiliary power supply device includes a battery and supplies power to the auxiliary heating unit. The control means controls charging / discharging of the capacitor of the auxiliary power supply device, and causes the auxiliary power supply device to charge the capacitor when the capacitor can be charged.
An example of the capacitor is an electric double layer capacitor.
JP 2004-310055 A

  An electric double layer capacitor has the property that deterioration progresses as the state close to full charge continues. Therefore, in order to extend the life of the electric double layer capacitor, it is preferable not to continue the state close to full charge as much as possible. However, in the past, in preparation for power feeding to the auxiliary heating element, it is made to be as close to full charge as possible, and as a result, the electric double layer capacitor is shortened.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to extend the life of a battery while enabling power supply to an auxiliary heating element at an appropriate timing without impairing the function as an auxiliary power supply device.

  In order to solve the above-mentioned problems, in the present invention, as a first means, a pair of fixing rollers which have a main heating element and an auxiliary heating element built in one and face each other in a state where their peripheral surfaces are in close contact with each other, A main power supply device that supplies power to the heating element, an auxiliary power supply device that includes a chargeable / dischargeable capacitor, and that supplies power from the capacitor to the auxiliary heating element, and a control that controls charging and discharging of the capacitor of the auxiliary power supply device A fixing device for fixing the toner image on the recording medium to the recording medium by pressurizing and heating the recording medium passing between the pair of fixing rollers, wherein the control device is in an idle state. When a predetermined time elapses from the time when the power is switched to the power saving mode, the auxiliary power supply device is set to the time required to fully charge the battery from the predetermined time when the idle state is set as a reference time ( Conductive duration) obtained by subtracting the time (charging wait time) has adopted a fixing device to start charging of the capacitor at the time of the lapse.

  Further, as a second means, in the fixing device according to the first means, the control device has a detecting means for detecting a terminal voltage before charging the capacitor, and the charging is required according to the terminal voltage. The one that determines the time was adopted.

  As a third means, in the fixing device according to the first or second means, the control device defines a deterioration state of the capacitor based on a predetermined condition, and determines the charge required time according to the deterioration state. Adopted what to decide.

  As a fourth means, in the fixing device according to the first means, the control device may perform the charging according to the predetermined time, a terminal voltage before charging the capacitor, and a deterioration coefficient indicating a deterioration state of the capacitor. It has a detecting means for storing a standby time as a table and detecting the terminal voltage, defining the deterioration coefficient based on a predetermined condition, and charging the battery according to the predetermined time, the terminal voltage, and the deterioration coefficient. The system used to obtain the waiting time from the table.

  Furthermore, in the present invention, as a fifth means, there is provided an image forming apparatus comprising a fixing device according to any one of the first to fourth means, and fixing a toner image formed on a recording medium using the fixing device. Adopted.

  According to the present invention, when a predetermined time elapses after entering the idle state, the mode shifts to the power saving mode, the heating of the fixing roller is stopped in the power saving mode, and the fixing roller temperature is gradually lowered by this. When returning to a predetermined temperature when starting, fully charge the capacitor before shifting to the power saving mode, and use the auxiliary power supply together with the main power supply to speed up the temperature recovery. Without charging the battery to the power saving mode by starting charging the battery at the time when the time required for subtracting the charging time from the predetermined time has elapsed with the reference time as the idle time. Since the charging of the battery was terminated immediately before the transition, it was possible to supply power at an appropriate timing without impairing the function as an auxiliary power supply. An undervoltage condition of vessels longer to thereby life of the capacitor.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a functional configuration of the fixing device according to the present exemplary embodiment. As shown in FIG. 1, the fixing device includes a main power switch 1 (main power device), an auxiliary power device 2, a pair of fixing rollers 3A and 3B, and a control device 4.
The auxiliary power supply 2 includes a rectifier circuit 2a, a charging circuit 2b, a selection switch 2c, a capacitor 2d (capacitor), and a discharge circuit 2e. One fixing roller 3A includes a main heater 3a (main heating element) and an auxiliary heater. 3b (auxiliary heating element) is incorporated, and the control device 4 further includes an opening / closing switch 4a, a temperature sensor 4b, and a control unit 4c (detecting means).

  The main power switch 1 is an open / close switch that regulates the supply of commercial AC 100V to the main heater 3a, and turns on / off the supply of AC 100V to the main heater 3a based on an open / close signal input from the control unit 4c. To do. The auxiliary power supply 2 supplies (power feeds) power to the auxiliary heater 3b.

The rectifier circuit 2a rectifies AC 100V, which is AC power, to convert it into DC power and outputs it to the charging circuit 2b. The charging circuit 2b charges the capacitor 2d based on the DC power, and is a constant current charging circuit that outputs a constant current, for example.
The selection switch 2c is a switch that selectively selects the output terminal of the charging circuit 2b or the input terminal of the discharging circuit 2e, and is either the output terminal or the input terminal based on a selection signal input from the control unit 4c. Is connected to one end of the capacitor 2d.

As is well known, the capacitor 2d is a two-terminal electric double layer capacitor capable of storing a relatively large charge among various capacitors. One end of the capacitor 2d is connected to the common terminal of the selection switch 2c, and the other end is a reference. It is connected to a potential (eg ground potential). Further, one end of the capacitor 2d (that is, a common terminal of the selection switch 2c) is connected to the control unit 4c as shown in the figure.
The discharge circuit 2e controls the discharge of the charge from the capacitor 2d. For example, the discharge circuit 2e discharges the charge stored in the capacitor 2d as a constant current and outputs it to the open / close switch 4a.

The fixing rollers 3A and 3B are a pair of rollers that face each other in a state where their peripheral surfaces are in close contact with each other, and rotate in opposite directions to sandwich the recording medium in a pressed state so that a toner image on the recording medium is obtained. Let it settle.
The main heater 3a is an electric heater provided in one of the pair of fixing rollers 3A and 3B, that is, in the fixing roller 3A, and generates heat when commercial power that is AC power is supplied from the main power switch 1. To do. The auxiliary heater 3b is an electric heater provided in the fixing roller 3A in the same manner as the main heater 3a, and generates heat when supplied with DC power supplied from the auxiliary power supply 2 (DC power discharged by the capacitor 2d). To do.

  The open / close switch 4a is provided between the output end of the discharge circuit 2e and the auxiliary heater 3b, and the DC power output from the output end of the discharge circuit 2e based on a control signal input from the control unit 4c. The supply to the auxiliary heater 3b is turned ON / OFF. The temperature sensor 4b detects the temperature of the fixing roller 3A and outputs the detected temperature to the control unit 4c.

The control unit 4c controls the overall operation of the fixing device based on a control program and various control data stored in the internal memory, and performs control calculation based on the control program and various control data. A CPU (Central Processing Unit) to be performed and other units (that is, a main power switch 1, a selection switch 2c, an open / close switch 4a, a temperature sensor 4b, and the like) are configured with various input / output interface circuits and the like that exchange signals. The control unit 4c also functions as a detection unit that detects the terminal voltage of the capacitor 2d as an amount indicating the amount of electricity stored in the capacitor 2d.
The control unit 4c controls each switch (the main power switch 1, the selection switch 2c, and the open / close switch 4a) based on the temperature detected by the temperature sensor 4b (the temperature of the fixing roller 3A).

In addition, when the control unit 4c is in an idle state (that is, a state where the start operation, operation acceptance, fixing operation, or the like is finished) and a predetermined time elapses, the control unit 4c shifts to the power saving mode and transfers to the above-described units other than the CPU. To save power by stopping the power supply.
Further, the control unit 4c stores a table as shown in FIG. 2 as one of the control data. This table shows the charge required according to the time until the transition to the power saving mode (power saving mode transition time), the terminal voltage before charging the capacitor 2d (voltage at the start of charging), and the deterioration coefficient of the capacitor 2d. (A) is an example in which the power saving mode transition time is 15 minutes (default value), and (b) is the power saving mode transition time of 1 minute (user) This is an example in the case of setting value).
The required charging time in the table is calculated by the following equation (1).
Charging time = [{(full charge voltage−voltage at the start of charge) / full charge voltage} × 60 seconds] × deterioration coefficient
(1)
The charging standby time in the table is calculated by the following equation (2).
Charging standby time = Power saving mode transition time-Charging time (2)

The full charge voltage of the capacitor 2d in this embodiment is 40V.
The deterioration coefficient is a value determined by the control unit 4c, and is 1 in the initial state where the integrated value of the charging time to the capacitor 2d is 0, and 2 in the final state where the integrated value exceeds a predetermined threshold. The controller 4c accumulates the charging time for the capacitor 2d, stores the accumulated value, and determines the deterioration coefficient based on the accumulated value.
Further, when the required charging time exceeds the power saving mode transition time, the charging standby time becomes a negative value according to the above equation (2), so the charging standby time is set to 0 regardless of the equation (2). .

The fixing device functions as a component of an image forming apparatus that forms a toner image on a recording medium based on an electrophotographic system. As is well known, such an image forming apparatus writes an electrostatic latent image on the surface of the photosensitive member by exposing the photosensitive member according to an image to be formed, and develops the electrostatic latent image with a developing device. The toner image is formed, and the toner image is transferred onto the surface of the recording medium to form an image with toner on the recording medium. For example, the functions of a printer, a copier, a facsimile, or each of these devices are combined. Such as a multifunction machine.
The control device 4 is a control device that comprehensively controls such an image forming apparatus, and shows a control function relating to fixing of a toner image on a recording medium using the fixing rollers 3A and 3B as one functional component. It is a thing.

  The image forming apparatus includes an operation unit that receives an operation from a user. The operation unit receives the setting of the power saving mode transition time. When the user sets the power saving mode transition time in the operation unit, a signal indicating the value is output from the operation unit to the control device included in the image forming apparatus, and the control device 4 included in the fixing device includes The power saving mode transition time is transmitted to and stored in the control unit 4c.

Next, a characteristic operation of the fixing device having the above-described configuration will be described with reference to FIG. FIG. 3 is a graph showing the timing of charging the capacitor 2d performed between the start of the idle state and the transition to the power saving mode.
When starting up the fixing device, the control unit 4c supplies AC 100V (main power) to the main heater 3a by controlling the main power switch 1 to be in the ON state. In addition, the control unit 4c controls the selection switch 2c so as to select the input terminal of the discharge circuit 2e and controls the open / close switch 4a to be in the ON state, whereby the DC power (auxiliary) output from the capacitor 2d is controlled. Power) is supplied to the auxiliary heater 3b through the discharge circuit 2e. As a result, the temperature of the fixing roller 3A starts to rise rapidly. At the same time, the electric charge accumulated in the capacitor 2d is consumed, the amount of electricity stored in the capacitor 2d decreases rapidly, and the voltage decreases (t1 → t2 in FIG. 3).

  When the controller 4c determines that the temperature of the fixing roller 3A has reached a predetermined temperature based on the temperature detected by the temperature sensor 4b, the controller 4c enters an idle state (t2 in FIG. 3). In the idle state, the controller 4c performs ON / OFF control of the main power switch 1 based on the temperature detected by the temperature sensor 4b so as to keep the temperature of the fixing roller 3A at a predetermined temperature. At this time, the control unit 4c controls the open / close switch 4a to be in an OFF state, and stops power supply to the auxiliary heater 3b.

Moreover, the control part 4c measures the time after becoming an idle state, and when the power saving mode transition time elapses (t2 → t4 in FIG. 3), it shifts to the power saving mode (t4 in FIG. 3).
Here, prior to the transition to the power saving mode, the control unit 4c acquires the charging standby time according to the power saving mode transition time, the terminal voltage of the capacitor 2d, and the deterioration coefficient from the table shown in FIG. For example, when the power saving mode transition time is 15 minutes, the terminal voltage of the capacitor 2d is 20V, and the deterioration factor is 1, the control unit 4c uses the table shown in FIG. A value of “14.5 minutes” is acquired.
Then, the control unit 4c sets the selection switch 2c so as to select the output terminal of the charging circuit 2b when the charging standby time (for example, 14.5 minutes) elapses from the idle state (t3 in FIG. 3). By controlling, the charging circuit 2b starts charging the capacitor 2d. As a result, the charged amount of the capacitor 2d increases and the voltage rises (t3 → t4 in FIG. 3). The charging of the capacitor 2d is completed by the time of shifting to the power saving mode (t4 in FIG. 3).

  The fixing device is not limited to the idle state after the start-up operation illustrated above, but the idle state when no operation is performed after the operation acceptance by the operator is ended, or the operation of the fixing operation is ended. The timing control for charging the capacitor 2d as shown in FIG. 3 is performed in any idle state such as an idle state when no operation is performed later.

As described above, according to the present embodiment, the charging of the capacitor 2d is finished immediately before the transition to the power saving mode, so that the low voltage state of the capacitor 2d can be lengthened to extend the life of the capacitor 2d.
And according to this embodiment, since the charge of the capacitor | condenser 2d is finished before transfer to power saving mode, the function of the auxiliary power supply device 2 is not impaired. That is, the control unit 4c shifts to the power saving mode when a predetermined time elapses after entering the idle state, stops the heating of the fixing roller 3A in the power saving mode, and thereby gradually reduces the temperature of the fixing roller 3A. When returning to a predetermined temperature when starting the fixing operation, the auxiliary power supply device is used together with the main power supply device to speed up the temperature recovery. However, since the capacitor 2d is sufficiently charged before shifting to the power saving mode, the auxiliary power supply The function of the device 2 is not impaired.

In the present embodiment, the deterioration coefficient is determined based on the integrated value of the charging time for the capacitor 2d. However, in the implementation, for example, a printing provided in an image forming apparatus including the fixing device as one component. It may be determined based on the count number of the sheet counter.
Further, the deterioration coefficient may be determined based on a voltage change rate due to deterioration of the capacitor 2d.
Furthermore, in this embodiment, as shown in FIG. 2, the charging standby time is determined by acquiring the charging standby time from a table in which values calculated in advance are stored. The calculation formulas such as (1) and (2) may be stored and determined by calculating the charging standby time using the calculation formula each time the engine enters the idle state.
Further, even if a table is not prepared for all values that can be set as the power saving mode transition time, for example, skipping values are set as representative values every few minutes (for example, 1, 3,..., 12, 15 minutes). About) It is also possible to prepare a table and refer to a table of representative values closest to the set value of the power saving mode transition time.

FIG. 2 is a block diagram illustrating a functional configuration of a fixing device according to an embodiment of the present invention. FIG. 3 is a table that defines a power saving mode transition time, a charging start time voltage of a capacitor, and a charging required time and a charging standby time according to a capacitor deterioration coefficient according to an embodiment of the present invention, and FIG. This is an example when the transition time is 15 minutes, and (b) is an example when the power saving mode transition time is 1 minute. It is a graph which shows the timing of the charge to the capacitor | condenser performed between the idle state start in 1 embodiment of this invention and power saving mode transfer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Main power switch (main power supply device), 2 ... Auxiliary power supply device, 2a ... Rectifier circuit, 2b ... Charging circuit, 2c ... Selection switch, 2d ... Capacitor (capacitor), 2e ... Discharge circuit, 3A, 3B ... Fixing roller 3a ... main heater (main heating element), 3b ... auxiliary heater (auxiliary heating element), 4 ... control device, 4a ... open / close switch, 4b ... temperature sensor, 4c ... control unit (detection means)

Claims (5)

A main heating element and an auxiliary heating element are incorporated in one, a pair of fixing rollers facing each other in a state where their peripheral surfaces are in close contact, a main power supply device that supplies power to the main heating element, and a chargeable / dischargeable battery An auxiliary power supply device that supplies power from the capacitor to the auxiliary heating element; and a control device that controls charging / discharging of the capacitor of the auxiliary power supply device; and a recording medium that passes between the pair of fixing rollers. A fixing device for fixing a toner image on a recording medium to the recording medium by applying pressure and heating,
The control device shifts to a power saving mode when a predetermined time elapses after entering the idle state, while the auxiliary power supply device is fully charged from the predetermined time to the auxiliary power supply device with the time when the idle state is entered as a reference time. The charging device is characterized in that the charging of the capacitor is started when a time (charge waiting time) obtained by subtracting the time required for charging (charge required time) has elapsed.   2. The fixing device according to claim 1, wherein the control device includes a detecting unit that detects a terminal voltage before charging the capacitor, and determines the required charging time according to the terminal voltage.   The fixing device according to claim 1, wherein the control device defines a deterioration state of the capacitor based on a predetermined condition, and determines the required charging time according to the deterioration state. The controller is
Storing the charging standby time according to the predetermined time, a terminal voltage before charging of the capacitor and a deterioration coefficient indicating a deterioration state of the capacitor as a table;
Detecting means for detecting the terminal voltage;
Defining the degradation coefficient based on a predetermined condition;
The fixing device according to claim 1, wherein the charging standby time is acquired from the table according to the predetermined time, the terminal voltage, and the deterioration coefficient.   An image forming apparatus comprising the fixing device according to claim 1, wherein a toner image formed on a recording medium is fixed using the fixing device.

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