JP2019174728A - Image formation device - Google Patents

Abstract

To achieve an image formation device that dehumidifies inside a device in power consumption mode at a low cost.SOLUTION: A fixing instrument 9 comprises a fixation heater 11 to which AC electricity based on a commercial power source is energized. An AC switching unit 12 is configured to turn ON/OFF the energization of the AC power to the fixation heater 11. A power source circuit 13 is configured to generate DC electricity from the commercial power source. A controller 31, to which the DC electricity is supplied as power source electricity, is configured to control the AC switching unit 12 and perform temperature control of the fixation heater 11. A DC switching unit 41 is configured to, when the energization of the AC electricity to the fixation heater 11 is turned OFF by the AC switching unit 12, energize the DC electricity to the fixation heater 11, and when the energization of the AC electricity to the fixation heater 11 is turned ON by the AC switching unit 12, shut down the energization of the DC electricity to the fixation heater 11.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus.

  An electrophotographic image forming apparatus includes a fixing device that fixes a toner image on a printing paper. In a certain image forming apparatus, a halogen heater and a ceramic heater are provided in the heat roller of the fixing device, and only the ceramic heater is energized to suppress power consumption during standby when the heat roller is stopped. (For example, refer to Patent Document 1).

JP 2002-148989 A

  As described above, in-machine dehumidification may be performed by energizing one heater during standby. However, in the above-described image forming apparatus, it is necessary to provide two heaters in the fixing unit and to control the two heaters independently, which increases the cost of the apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that performs in-machine dehumidification in a power saving mode at low cost.

  An image forming apparatus according to the present invention is designated by a fixing device including a fixing heater that is supplied with AC power based on a commercial power source, and an AC switching unit that turns on / off the supply of AC power to the fixing heater. A power supply circuit for generating DC power from the commercial power supply with the output voltage, a controller for supplying DC power as the power supply power with the output voltage, and controlling the temperature of the fixing heater by controlling the AC switching unit, When the AC power is not supplied to the fixing heater by the AC switching unit, the DC power is supplied to the fixing heater, and the AC power is not supplied to the fixing heater by the AC switching unit. And a DC switching unit that cuts off the supply of the DC power to the fixing heater.

  According to the present invention, an image forming apparatus that performs in-machine dehumidification in a power saving mode at low cost can be obtained.

  These and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 is an apparatus having an electrophotographic printing function, such as a printer, a facsimile machine, a copying machine, or a multifunction machine.

  The image forming apparatus of this embodiment has a tandem color developing device. The color developing device includes photosensitive drums 1a to 1d, exposure devices 2a to 2d, and developing devices 3a to 3d. The photoconductor drums 1a to 1d are four-color photoconductors of cyan, magenta, yellow, and black.

  The exposure devices 2a to 2d irradiate the photosensitive drums 1a to 1d with laser light to form electrostatic latent images. The exposure apparatuses 2a to 2d include a laser diode that is a light source of laser light and optical elements (lenses, mirrors, polygon mirrors, etc.) that guide the laser light to the photosensitive drums 1a to 1d.

  Further, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a static eliminator and the like are arranged. The cleaning device removes residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 1a to 1d after the primary transfer.

  Each of the developing devices 3a to 3d is mounted with a toner cartridge filled with toners of four colors of cyan, magenta, yellow and black, and the toner is supplied from the toner cartridge and constitutes a developer together with the carrier. The developing devices 3a to 3d attach the toner to the electrostatic latent images on the photosensitive drums 1a to 1d to form a toner pattern.

  The photosensitive drum 1a, the exposure device 2a, and the developing device 3a develop magenta, and the photosensitive drum 1b, the exposure device 2b, and the developing device 3b develop cyan, the photosensitive drum 1c, and the exposure device. Yellow development is performed by the device 2c and the developing device 3c, and black development is performed by the photosensitive drum 1d, the exposure device 2d, and the developing device 3d.

  The intermediate transfer belt 4 is an annular image carrier that contacts the photosensitive drums 1a to 1d and primarily transfers the toner images on the photosensitive drums 1a to 1d. The intermediate transfer belt 4 is stretched around the driving roller 5 and circulates in the direction from the contact position with the photosensitive drum 1d to the contact position with the photosensitive drum 1a by the driving force from the driving roller 5.

  The transfer roller 6 brings the conveyed paper into contact with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the paper. The sheet on which the toner image is secondarily transferred is conveyed to the fixing device 9.

  The roller 7 has a cleaning brush, and the cleaning brush is brought into contact with the intermediate transfer belt 4 to remove the toner remaining on the intermediate transfer belt 4 after the transfer of the toner image onto the paper.

  The sensor 8 is an optical sensor used for measuring the density of the toner pattern, and irradiates the intermediate transfer belt 4 with a light beam and detects the reflected light. For example, when adjusting the toner density, the sensor 8 irradiates a predetermined region of the intermediate transfer belt 4 with a light beam, detects the reflected light, and outputs an electrical signal corresponding to the light amount.

  The fixing device 9 fixes the toner image that has been secondarily transferred onto a sheet by a heating and pressing method.

  FIG. 2 is a circuit diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention.

  As shown in FIG. 2, the fixing device 9 includes a fixing heater 11 that is supplied with AC power based on a commercial power source. The fixing heater 11 is a resistance heating element heater and is disposed in the fixing roller. For example, the fixing heater 11 is a planar heater.

  Further, as shown in FIG. 2, an AC switching unit 12, a fuse FS1, a relay CR, and choke coils LC1 and LC2 are provided between the commercial power source and the fixing heater 11.

  The AC switching unit 12 includes a switching element (in this case, a bidirectional thyristor) connected in series to the fixing heater 11, and turns ON / OFF the energization of AC power to the fixing heater 11 by the switching element. Since AC power is supplied to the fixing heater 11, a bidirectional thyristor capable of conducting current in both directions is used for the AC switching unit 12.

  The image forming apparatus illustrated in FIGS. 1 and 2 includes a power supply circuit 13 and a control board 14 that is supplied with power from the power supply circuit 13.

  The power supply circuit 13 generates DC power from a commercial power supply with a specified output voltage, and supplies power to the controller 31 that controls the fixing heater 11. In the normal mode, the power supply circuit 13 supplies DC power to a load such as the control board 14 at a predetermined reference voltage (for example, 24 volts).

  In the power supply circuit 13, AC power obtained from a commercial power source is rectified by the diode bridge DB, and the rectified DC power is stepped down to a rated voltage by a DC / DC converter and output. In front of the diode bridge DB, a fuse FS2, choke coils LC3 and LC4, and the thermistor TH are provided. Further, a smoothing capacitor C1 is provided after the diode bridge DB.

  The DC / DC converter portion of the power supply circuit 13 includes a converter switching element Q1, a control unit 21, a transformer TR, and a rectifier circuit 22.

  Converter switching element Q <b> 1 is connected to the primary winding of transformer TR and performs a switching operation in accordance with a control signal from control unit 21. Here, converter switching element Q1 is a field effect transistor (FET).

  The control unit 21 is a circuit (for example, an IC chip) that outputs a control signal for controlling on / off of the converter switching element Q1.

  The rectifier circuit 22 includes a diode D and a smoothing capacitor C2, and rectifies AC power induced in the secondary side winding of the transformer TR to generate DC power. The control unit 21 adjusts the duty of the control signal so that the rectified DC voltage becomes a predetermined voltage (a reference voltage in the normal mode).

  The control board 14 is provided with a controller 31 and a power saving control circuit 32. Therefore, the output voltage of the power supply circuit 13 is applied to the controller 31 and the power saving control circuit 32 as the power supply voltage.

  The controller 31 includes an ASIC (Application Specific Integrated Circuit), a processor that operates in accordance with a control program, and controls the AC switching unit 12 by applying a heater control signal to the AC switching unit 12. Control and so on.

  Further, the controller 31 sets the operation mode to one of a normal mode and a power saving mode (a mode with less power consumption than the normal mode) based on a predetermined condition setting, and controls each unit according to the operation mode.

  The DC switching unit 41 (a) energizes the fixing heater 11 with DC power output from the power supply circuit 13 when the AC switching unit 12 turns off the AC power to the fixing heater 11, and (b) When energization of AC power to the fixing heater 11 is ON by the AC switching unit 12, energization of DC power output from the power supply circuit 13 to the fixing heater 11 is cut off.

  The DC switching unit 41 includes a switching element 41a and a switching element 41b.

  The switching element 41 a is provided between one end of the fixing heater 11 and the high-voltage side output end of the power supply circuit 13, and prevents a current from one end of the fixing heater 11 to the high-voltage side output end of the power supply circuit 13. Depending on the level of the power saving signal), energization from the high-voltage side output end of the power supply circuit 13 to one end of the fixing heater 11 is permitted or blocked.

  The switching element 41b is provided between the other end of the fixing heater 11 and the low-voltage side output end of the power supply circuit 13, and blocks current from the low-voltage side output end of the power supply circuit 13 to the other end of the fixing heater 11 for control. Depending on the level of the signal (power saving signal), energization from the other end of the fixing heater 11 to the low voltage side output end of the power supply circuit 13 is permitted or blocked.

  Here, unidirectional thyristors are used for the switching elements 41a and 41b.

  Note that the DC switching unit 41 may be provided on the control board 14. In that case, for example, the switching elements 41 a and 41 b are surface-mounted on the control board 14.

  The power saving control circuit 32 of the control board 14 is a circuit that performs on / off control of the DC switching unit 41. For example, the power saving control circuit 32 supplies a power saving signal to the gates of the switching elements 41a and 41b of the DC switching unit 41, thereby turning off the switching elements 41a and 41b by setting the power saving signal to a low level in the normal mode. In the power saving mode, the power saving signal is set to the high level to turn on the switching elements 41a and 41b.

  Further, the power saving control circuit 32 controls the power supply circuit 13 when the DC switching unit 41 supplies DC power to the fixing heater 11 to control a predetermined output voltage lower than the reference voltage (for example, when the reference voltage is 24 volts). Is 8 volts).

  Specifically, the power saving control circuit 32 also supplies a power saving signal to the control unit 21 of the power supply circuit 13. And the control part 21 changes the target value of the output voltage of the power supply circuit 13 according to a power saving signal. When the power saving signal is at a low level, the control unit 21 controls the converter switching element Q1 so that the output voltage of the power supply circuit 13 becomes the reference voltage with the target value as the reference voltage, and (b) the saving When the power signal is at a high level, the target value is set to a predetermined output voltage lower than the reference voltage, and converter switching element Q1 is controlled so that the output voltage of power supply circuit 13 becomes the predetermined output voltage.

  The power saving control circuit 32 stops the operation of the controller 31 when the above-described DC power is supplied to the fixing heater 11 in the power saving mode, for example. At this time, the power saving control circuit 32 may cut off the power supply to the controller 31.

  Next, the operation of the image forming apparatus will be described.

  The controller 31 sets the operation mode to the normal mode or the power saving mode based on a predetermined condition setting.

  In the initial state (normal mode), the power supply circuit 13 supplies power to the controller 31 with a reference voltage. In the normal mode, the controller 31 causes the power saving control circuit 32 to output a low level power saving signal. As a result, the power supply circuit 13 continues to supply power to the controller 31 with the reference voltage, and the DC switching unit 41 interrupts the electrical connection between the power supply circuit 13 and the fixing heater 11.

  In the normal mode, the controller 31 controls the AC switching unit 12 to control the temperature of the fixing heater 11 during the printing operation of the image forming apparatus by setting the relay CR to a conductive state.

  When a condition specified by a predetermined condition setting (for example, a no-operation period longer than a predetermined time) is satisfied, the controller 31 switches the operation mode from the normal mode to the power saving mode. In the power saving mode, the printing operation is not performed, and the controller 31 turns off the AC switching unit 12, turns off the relay CR, disconnects the fixing heater 11 from the commercial power source, and further controls power saving. The circuit 32 is caused to output a high-level power saving signal, and then the operation is stopped. After the operation of the controller 31 is stopped, the relay CR and the AC switching unit 12 remain in the off state, and the fixing heater 11 is continuously disconnected from the commercial power source. The power consumption in the power saving control circuit 32 is less than the power consumption of the controller 31.

  After the operation of the controller 31 is stopped, the power saving control circuit 32 continuously outputs a high level power saving signal in the power saving mode. As a result, in the power saving mode, the output voltage of the power supply circuit 13 is lower than the reference voltage, and the power supply circuit 13 and the fixing heater 11 are electrically connected. Electric power is supplied to the fixing heater 11. At this time, the fixing heater 11 consumes power corresponding to the voltage and generates heat. At this time, the fixing heater 11 generates heat with a heat generation amount necessary for in-machine dehumidification.

  Thereafter, when a condition specified by a predetermined condition setting (for example, acceptance of a print request) is satisfied, the controller 31 returns the operation mode from the power saving mode to the normal mode.

  As described above, according to the above-described embodiment, the fixing device 9 includes the fixing heater 11 that is energized with AC power based on the commercial power source. The AC switching unit 12 turns on / off energization of AC power to the fixing heater 11. The power supply circuit 13 generates DC power from a commercial power supply with a designated output voltage. The controller 31 is supplied with DC power as power supply power with the output voltage, and controls the AC switching unit 12 to control the temperature of the fixing heater 11. The DC switching unit 41 supplies the above-described DC power to the fixing heater 11 when the AC switching unit 12 turns off the AC power to the fixing heater 11, and the AC switching unit 12 supplies the AC power to the fixing heater 11. When the energization of power is on, the above-described energization of the DC power is cut off to the fixing heater 11.

  Accordingly, it is not necessary to provide a heater for in-machine dehumidification separately from the fixing heater 11, and in-machine dehumidification in the power saving mode is performed at low cost.

  For example, if the voltage (effective value) of the commercial power supply is 100 volts and the resistance value of the fixing heater 11 is 11.5 ohms, the power consumption in the fixing heater 11 is 870 watts when continuously energized in the normal mode. When the output voltage of the power supply circuit 13 is 8 volts in the power saving mode, the power consumption in the fixing heater 11 is 5.57 watts. In this case, in the power saving mode, the fixing heater 11 generates heat with a power consumption of 5.57 watts, and the internal temperature is unlikely to decrease, and the internal dehumidification is performed.

  Various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. That is, such changes and modifications are intended to be included within the scope of the claims.

  The present invention is applicable to, for example, an electrophotographic image forming apparatus.

DESCRIPTION OF SYMBOLS 9 Fixing device 11 Fixing heater 12 AC switching part 13 Power supply circuit 14 Control board 31 Controller 32 Power saving control circuit 41 DC switching part

Claims (3)

A fixing device including a fixing heater energized with AC power based on a commercial power source;
An AC switching unit for turning on / off the energization of the AC power to the fixing heater;
A power supply circuit for generating DC power from the commercial power supply at a specified output voltage;
DC power is supplied as power supply power at the output voltage, a controller for controlling the AC switching unit and controlling the temperature of the fixing heater;
When the AC power is not supplied to the fixing heater by the AC switching unit, the DC power is supplied to the fixing heater, and the AC power is supplied to the fixing heater by the AC switching unit. A DC switching unit that cuts off the DC power to the fixing heater,
An image forming apparatus comprising: A power saving control circuit for performing on / off control of the DC switching unit;
The power supply circuit supplies power to the controller with a predetermined reference voltage,
The power saving control circuit controls the power supply circuit to specify the output voltage lower than the reference voltage when the DC power is supplied to the fixing heater in the DC switching unit;
The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein the operation of the controller is stopped when the DC power is supplied to the fixing heater.

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