JP5242031B2 - Fixing device, image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device that performs a fixing process for fixing a toner image transferred onto a transfer material such as paper in an image forming apparatus, and an image forming apparatus including the fixing device.

  As an apparatus for forming an image by fixing toner on a recording medium such as paper, there is an image forming apparatus such as a printer, a copier, a facsimile, or a multifunction machine in which the functions of these devices are combined. In general, a fixing device that performs a fixing process for fixing a toner image transferred onto a transfer material such as paper to the transfer material is mounted. This fixing device mainly includes a fixing roller and a heating unit. The fixing roller is a pair of rollers facing each other in a state where the peripheral surfaces are in close contact with each other, and the heating unit heats a fixing roller (heating roller) located on the toner side of the recording medium among the pair of fixing rollers. Is. The fixing device configured in this manner fixes the toner image transferred onto the recording medium by the photosensitive member to the recording medium by pressing and heating the recording medium passing between the pair of fixing rollers.

  In the fixing device, the heating unit includes a main heating element and an auxiliary heating element, a main power supply that supplies electric power to the main heating element, and electric power (auxiliary power) is supplied to the auxiliary heating element. An auxiliary power supply device using a multilayer capacitor as a power source is provided. Such a fixing device includes a sensor that detects the temperature of the heated body (heating roller), and turns on / off the power supply from the auxiliary power supply to the fixing device based on the temperature of the heating roller detected by the sensor. The temperature of the heating roller is adjusted to a predetermined temperature by performing OFF control.

On the other hand, there are, for example, the following Patent Documents 1 and 2 as technical documents related to this type of technical field. Japanese Patent Application Laid-Open No. 2004-133830 discloses a technique for supplying power to the heater by a main power supply device and an auxiliary power supply device when the fixing device is started from a standby state in a fixing device having a main power supply device and an auxiliary power supply device. It is disclosed. Patent Document 2 discloses a technique for supplying power from an auxiliary power supply device in a standby state.
Japanese Patent No. 3588006 JP 2004-266984 A

  By the way, in the auxiliary power supply device, the start-up time of the fixing device can be shortened as the suppliable power is larger.

  However, if the ability to supply a large supply power is installed in the product from the beginning of manufacture, the electric double layer capacitor is expensive, leading to an increase in the cost of the fixing device, and consequently the image forming device. For users who do not particularly require a reduction in startup time, the economic burden increases and the above-described capabilities are wasted. Therefore, it is preferable that the above-described capability be provided only for a user who requests a reduction in the startup time of the fixing device.

  In view of this point, when the electric double layer capacitor is configured to be collectively replaced with one having higher ability, even if the electric double layer capacitor before replacement can still be used, the capacitor is not Since it is removed as unused, resources may be wasted, and there is a risk of increasing the cost accordingly. The cited documents 1 and 2 do not disclose this point.

  The present invention has been made to solve the above-described problems, and to a user who requests a reduction in the startup time of the fixing device without wasting a capacitor mounted from the beginning of manufacture. It is only an object of the present invention to provide a fixing device and an image forming apparatus that can increase the power supply capability of an auxiliary power supply device.

According to a first aspect of the present invention, there is provided a power storage device having a first capacitor , a first fixing heater for driving a fixing unit for fixing toner onto a recording sheet with electric power from an external power source, and the fixing unit from the power storage device. A fixing device comprising a second fixing heater driven by electric power and a converter installed between the power storage device and the second fixing heater, wherein the power storage device can be equipped with a second capacitor a pair of terminals that are configured, the power storage device has a first state for short-circuiting said pair of terminals, a short-circuit state between the pair of terminals is released, and said second capacitor said power storage A second state in which electric power is supplied to the second fixing heater by a series circuit of the first capacitor and the second capacitor by being mounted between the pair of terminals of the apparatus. It is, The converter outputs an output voltage of the power storage device so that a voltage supplied to the second fixing heater in the second state does not increase more than a voltage supplied to the second fixing heater in the first state. Accordingly, the fixing device includes output control means for keeping the voltage supplied to the second fixing heater constant .

According to this invention, it has the 2nd capacitor comprised so that attachment or detachment was possible in a pair of terminals with which an electrical storage device is equipped, and an electrical storage device is in the 1st state which short-circuits the pair of terminals, and the pair of terminals The short circuit state is released, and the second capacitor is mounted between the pair of terminals, whereby electric power is supplied to the second fixing heater by the series circuit of the first capacitor and the second capacitor. Since it is configured to be able to adopt the second state, when it is desired to shorten or maintain the startup time of the fixing device, a capacitor is added by attaching a second capacitor to the pair of terminals, If not required, the user can make a selection to keep the pair of terminals short-circuited .

The converter according to claim 1 includes output control means for controlling the output of the converter in accordance with the output of the power storage device.

  According to this invention, since the converter includes the output control means for controlling the output of the converter according to the output of the power storage device, the second fixing is performed even if a capacitor (second capacitor) is added to the power storage device. It becomes possible to make the output voltage to the heater constant. Therefore, even if a capacitor (second capacitor) is added to the power storage device, it is not necessary to replace the second fixing heater with one having a higher rated power.

According to a second aspect of the present invention, in the fixing device according to the first aspect, a harness for short-circuiting the pair of terminals is configured to be detachable from the pair of terminals, and the power storage device includes the pair of terminals. The harness and the second capacitor can be selectively mounted on the terminal.

According to the present invention, a fixing device capable of increasing the power supply capability of the auxiliary power supply device can be realized with a simple configuration only for a user who requires shortening or maintaining the startup time of the fixing device.

According to a third aspect of the present invention, there is provided an image forming unit that performs an image forming operation on a sheet based on image data, and a toner that adheres to the sheet with respect to the sheet after the image forming operation by the image forming unit. An image forming apparatus comprising the fixing device according to claim 1 , wherein the fixing device is fixed on a sheet.

According to the present invention, in the image forming apparatus, the action according to the first or second aspect of the invention can be obtained.

  According to the present invention, when shortening or maintaining the fixing device start-up time is required, a capacitor can be added in such a manner that a second capacitor is attached to the pair of terminals. The power supply capacity of the auxiliary power supply unit is limited to users who require shortening and maintaining the startup time of the fixing device without wasting the mounted capacitors and thus suppressing the cost increase. A fixing device and an image forming apparatus that can be increased can be realized.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view schematically showing an internal configuration of a multifunction peripheral as an example of an image forming apparatus according to an embodiment of the present disclosure. The multifunction device 1 has functions such as a copy function, a printer function, a scanner function, and a facsimile function. The multi-function device 1 includes a main body 2, a stack tray 3 disposed on the left side of the main body 2, a document reading unit 5 disposed on the top of the main body 2, and an upper side of the document reading unit 5. And a document feeding unit 6 disposed.

  An operation unit 47 is provided at the front part of the multifunction machine 1. The operation unit 47 displays a start key 471 for a user to input a print execution instruction, a ten key 472 for inputting the number of copies to be printed, operation guide information for various copying operations, and the like. A display unit 473 formed of a liquid crystal display or the like having a touch panel function, a reset key 474 for resetting setting contents set in the display unit 473, and a stop key for stopping a printing (image forming) operation being executed 475 and a function switching key 477 for switching between a copy function, a printer function, a scanner function, and a facsimile function.

  The document reading unit 5 includes a scanner unit 51 including a CCD (Charge Coupled Device) sensor and an exposure lamp, and a document table 52 and a document reading slit 53 made of a transparent member such as glass. The scanner unit 51 is configured to be movable by a drive unit (not shown). When reading a document placed on the document table 52, the scanner unit 51 is moved along the document surface at a position facing the document table 52, and the document image is scanned. The image data acquired while scanning is output to the control unit 10 (FIG. 2). Further, when reading a document fed by the document feeding unit 6, the document is moved to a position facing the document reading slit 53 and synchronized with the document feeding operation by the document feeding unit 6 via the document reading slit 53. The image of the original is acquired and the image data is output to the control unit 10.

  The document feeding unit 6 includes a document placing unit 61 for placing a document, a document discharge unit 62 for discharging a document whose image has been read, and a document placed on the document placing unit 61. A document transport mechanism 63 including a paper feed roller (not shown), a transport roller (not shown) and the like for feeding the paper one by one to a position facing the document reading slit 53 and discharging it to the document discharge section 62 is provided. The document conveyance mechanism 63 further includes a sheet reversing mechanism (not shown) that reverses the document and reversely conveys the document to a position facing the document reading slit 53, and scans both sides of the document through the document reading slit 53. 51 can be read.

  The document feeding unit 6 is provided so as to be rotatable with respect to the main body unit 2 so that the front side thereof can move upward. By moving the front side of the document feeder 6 upward to open the upper surface of the document table 52, the operator can place a read document, for example, a book in a spread state, on the upper surface of the document table 52. It has become.

  The main body 2 includes a plurality of paper feed cassettes 461, a paper feed roller 462 that feeds the recording paper from the paper feed cassette 461 one by one and transports it to the recording unit 40, and a recording paper transported from the paper feed cassette 461. And a recording unit 40 for forming an image.

  The recording unit 40 outputs an optical beam or the like based on the image data acquired by the scanner unit 51 to expose the photosensitive drum 43, and a developing unit 44 that forms a toner image on the photosensitive drum 43. A transfer unit 41 that transfers the toner image on the photosensitive drum 43 to the recording paper, and a fixing device 7 that heats the recording paper to which the toner image has been transferred and fixes the toner image to the recording paper (see FIGS. 2 and 1). 1, only the fixing roller 73 is shown), and conveyance rollers 463, 464, etc. that are provided in the sheet conveyance path in the recording unit 40 and convey the recording sheet to the stack tray 3 or the discharge tray 48.

  When forming images on both sides of the recording paper, the recording unit 40 forms an image on one side of the recording paper, and then the recording paper is nipped by the conveyance roller 463 on the discharge tray 48 side. . In this state, the conveyance roller 463 is reversed to switch back the recording paper, and the recording paper is sent to the paper conveyance path 49 to be conveyed again to the upstream area of the recording unit 40, and an image is formed on the other surface by the recording unit 40. Thereafter, the recording paper is discharged to the stack tray 3 or the discharge tray 48.

  FIG. 2 is a schematic diagram showing the fixing device 7 provided in the multifunction machine 1 and the surrounding internal configuration. The fixing device 7 includes a first power switch 71, an auxiliary power unit 72, a fixing roller 73, an auxiliary power switch 74, and a charging switch 75.

  The fixing roller 73 includes a pressure roller that applies pressure to the recording paper, and a heat roller that applies heat to the recording paper. The toner image on the recording paper is formed by sandwiching the recording paper between the two rollers in a press-contact state. Fix on recording paper. A fixing heater 730 for heating is provided in the heat roller of the fixing roller 73. FIG. 2 particularly shows the fixing heater 730 portion. The fixing heater 730 includes a first fixing heater 731 and a second fixing heater 732. The first fixing heater 731 is a halogen heater that generates heat with electric power supplied from an AC commercial power supply 8 (external power supply). The second fixing heater 732 is a halogen heater that generates heat with electric power supplied from the auxiliary power supply unit 72.

  The first power switch 71 is provided between the commercial power supply 8 and the first fixing heater 731, and determines whether or not to supply AC100V power from the commercial power supply 8 to the first fixing heater 731, that is, the first power switch 71. This is an open / close switch that switches whether to drive (heat generation) the fixing heater 731. The first power switch 71 turns on or off the AC 100 V power supply from the commercial power supply 8 based on an open / close signal input from the control unit 10 that controls the overall operation of the multifunction machine 1.

  The auxiliary power switch 74 is provided between the auxiliary power unit 72 and the second fixing heater 732, and determines whether or not power from the auxiliary power unit 72 is supplied to the second fixing heater 732, that is, the second fixing heater. This is an open / close switch for switching whether to drive (heat generation) 732. The auxiliary power switch 74 turns on or off the power supply from the auxiliary power unit 72 based on the open / close signal input from the control unit 10.

  The charging switch 75 is an open / close switch that is provided between the commercial power supply 8 and the auxiliary power supply unit 72 and switches whether power from the commercial power supply 8 is supplied to the auxiliary power supply unit 72. The charging switch 75 also turns on or off the power supply from the commercial power supply 8 based on the open / close signal input from the control unit 10. The control unit 10 turns on the charging switch 75 when the power consumption of the commercial power supply 8 is low in the multifunction device 1 such as when the sleep mode of the multifunction device 1 is executed (when waiting for printing) or when the main power is off. Charging by the charging device 721 and the power storage device 722 is performed.

  The auxiliary power supply unit 72 is provided as an auxiliary power supply for the commercial power supply 8 in order to supply power to the second fixing heater 732. The auxiliary power unit 72 includes a charging device 721, a power storage device 722, and a discharging device 723.

  Charging device 721 is an AC / DC converter for charging power storage device 722, and outputs a current obtained by rectifying AC 100 V of commercial power supply 8, which is AC power, to power storage device 722.

  The power storage device 722 includes an electric double layer capacitor 722a and the like, and charges the electric double layer capacitor 722a using the current from the charging device 721 as a charge, while discharging the electric charge charged in the electric double layer capacitor 722a. The current is output to the discharge device 723.

  The discharge device 723 uses the voltage output from the power storage device 722 as an input voltage, boosts the input voltage to a predetermined voltage suitable for the second fixing heater 732 as a load, and uses the boosted power to the second fixing heater. 732 is supplied. The discharge device 723 is an insulated DC / DC converter in which an input side and an output side are insulated by an insulated transformer.

  The control unit 10 controls the overall operation of the multifunction device 1. The control unit 10 controls the first power switch 71, the auxiliary power switch 74, and the charging switch 75 to be turned on and off. The control unit 10 drives the discharge device 723 at a predetermined timing, and switches the power supplied to the second fixing heater 732 to the power from the power storage device 722 whose output voltage has been converted by the discharge device 723.

  Next, the configuration of the discharge device 723 will be described. FIG. 3 is a circuit diagram illustrating a schematic configuration of the discharge device 723 and a connection relationship between the power storage device 722 and the second fixing heater 732.

  As shown in FIG. 3, the discharge device 723 includes a transformer 723a, a MOS transistor 723b, a PWM controller 723c, and a smoothing circuit 723d.

  A transformer (an example of an insulated converter) 723a is an insulated transformer, and includes a primary winding and a secondary winding that have a turn ratio suitable for generating a voltage necessary for the second fixing heater 732. . One end of the primary winding of the transformer 723a is connected to one end (+ voltage side) of the power storage device 722, and the other end of the primary winding is connected to the drain terminal of the MOS transistor 723b. Further, both ends of the secondary winding of the transformer 723a are connected to the smoothing circuit 723d.

  The MOS transistor 723 b is for switching the discharge current input from the power storage device 722. As described above, in the MOS transistor 723b, the drain terminal is connected to the other end of the primary winding of the transformer 723a, the source terminal is connected to the other end (−voltage side) of the power storage device 722, and the gate terminal is PWM. It is connected to the controller 723c. With the above configuration, the primary side of the transformer 723a is connected to the power storage device 722, and power from the power storage device 722 is output to the transformer 723a.

  When receiving an ON signal for driving the discharge device 723 from the control unit 10, the PWM controller 723 c is supplied with electric power from the power storage device 722 to the discharge device 723, and drives the discharge device 723 from the control unit 10. The switching operation of the MOS transistor 723b is controlled so that power supply from the power storage device 722 to the discharge device 723 is stopped when an off signal to be stopped is received.

  The PWM controller 723c generates a PWM signal so that the voltage output as the auxiliary power supply voltage from the smoothing circuit 723d becomes a predetermined constant value, and supplies the PWM signal to the gate terminal of the MOS transistor 723b. Thus, the switching operation of the MOS transistor 723b is controlled. As a result, even if the charging voltage of the electric double layer capacitor of the power storage device 722 gradually decreases due to discharging and the input voltage of the discharging device 723 decreases, the driving voltage of the second fixing heater 732 is held at a constant value, 2 Heat generation of the fixing heater 732 is stabilized. The PWM controller 723c corresponds to the output control means.

  The smoothing circuit 723d includes diodes D1 and D2, which are connected as shown in FIG. 3, a coil L, and a capacitor C, and smoothes the secondary winding voltage supplied from the secondary winding of the transformer 723a and outputs it as an auxiliary power supply voltage. To do. One of the output ends of the smoothing circuit 723d is connected to one end (+ voltage side) of the power storage device 722 in the same manner as one end of the primary winding of the transformer 723a. As the diode D2, a diode having an instantaneous withstand voltage is used so as not to be damaged by the inrush current generated at the initial driving of the second fixing heater 732. In addition, the other side of the output terminal of the smoothing circuit 723 d and the negative voltage side of the power storage device 722 are connected to the second fixing heater 732.

  That is, the auxiliary power supply unit 72 includes a discharge device 723 in which the input side (primary side) and the output side (secondary side) are insulated by the transformer 723a, and the primary side of the discharge device 723 is connected to the power storage device 722. Since one end of the secondary side is connected to the power storage device 722 and the other end of the secondary side is connected to the second fixing heater 732, the auxiliary power supply voltage at the power output terminal of the auxiliary power supply unit 72 is This is a voltage obtained by adding (superimposing) the charging voltage of 722 and the output voltage of the discharging device 723.

  Next, a more specific configuration of the auxiliary power unit 72 in the present embodiment will be described.

  In the auxiliary power supply unit 72 of the present embodiment, in addition to the electric double layer capacitor 722a (corresponding to the first capacitor) mounted on the power storage device 722 at the time of factory shipment (initial production), a further fixing device 7 is started. An electric double layer capacitor 722b (corresponding to the second capacitor: see FIG. 4) can be added to satisfy the user's request for shortening the raising time. This electric double layer capacitor 722b As an option, the power storage device 722 is detachable.

  That is, as shown in FIG. 4A, in the normal state before the optional electric double layer capacitor 722b is attached to the power storage device 722, the negative side of the electric double layer capacitor 722a that is originally installed is provided. The terminal T2 and the terminal T3 opposite to the terminal connected to the second fixing heater 732 of the auxiliary power switch 74 are short-circuited by a harness. Terminals T2 and T3 correspond to the pair of terminals.

  When the optional electric double layer capacitor 722b is attached to the power storage device 722, the user removes the harness from the terminals T2 and T3, and at the same time the one terminal a and the terminal in the optional electric double layer capacitor 722b. The terminal T2 is connected to the other terminal b of the electric double layer capacitor 722b and the terminal T3. Accordingly, as shown in FIG. 4B, the originally installed electric double layer capacitor 722a and the optional electric double layer capacitor 722b are connected in series to the second fixing heater 732. When the auxiliary power supply voltage is increased and the fixing device 7 is started up in a shorter time or the performance of the originally installed electric double layer capacitor 722a is deteriorated, the performance is compensated to compensate for the performance. The original performance of the multifunction device 1 can be maintained.

  Here, as described above, the discharge device 723 formed of an insulation type DC / DC converter outputs the output of the discharge device 723 so that the voltage supplied to the second fixing heater 732 is kept constant by the PWM controller 723c. Since the voltage is changed in accordance with the output voltage of the power storage device 722, even if the auxiliary power supply voltage is increased by mounting the optional electric double layer capacitor 722b (addition of the electric double layer capacitor), the second fixing heater 732 is more rated. There is no need to change the output (rated voltage).

  That is, if the discharge device 723 does not have a function of keeping the voltage supplied to the second fixing heater 732 constant, the voltage applied to the second fixing heater 732 increases by adding an electric double layer capacitor. It will increase by the increase of the auxiliary power supply voltage. Here, when the voltage exceeds the rated voltage of the second fixing heater 732, it is necessary to replace the second fixing heater 732 with a higher rated voltage. However, in this embodiment, since the voltage supplied to the second fixing heater 732 is kept constant, this is not necessary.

  As described above, in this case, it is not necessary to replace the heater with a larger rated output, and the electric double layer capacitor that can still be used is not wasted (while suppressing the cost increase as much as possible). Therefore, an option that can increase the auxiliary power supply voltage can be provided only for a user who desires a faster startup of the fixing device 7.

  Further, in a normal state before the optional electric double layer capacitor 722b is attached to the power storage device 722, the terminals T2 and T3 are short-circuited by a harness, and the electric double layer capacitor 722b is attached to the power storage device 722. In this case, the user removes the harness from the terminals T2 and T3 and connects the terminals a and b of the electric double layer capacitor 722b to the terminals T2 and T3. A configuration in which the auxiliary power supply voltage can be increased only for a user who requires shortening and maintenance can be realized with a relatively simple configuration.

  Note that this case can be applied not only to the multifunction machine but also to an image forming apparatus such as a copying machine or a facsimile machine.

1 is a side view schematically showing an internal configuration of a multifunction peripheral as an example of an image forming apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating a fixing unit provided in the multifunction peripheral and a peripheral internal configuration. It is a circuit diagram which shows the schematic structure of a pressure | voltage rise apparatus, and the connection relation of an electrical storage apparatus and a 2nd fixing heater. It is explanatory drawing of the characteristic part of an auxiliary power supply unit.

Explanation of symbols

1 MFP 5 Document Reading Unit 6 Document Feeding Unit 7 Fixing Device 71 Power Switch 72 Auxiliary Power Unit 73 Fixing Roller 74 Auxiliary Power Switch 75 Charging Switch 721 Charging Device 722 Power Storage Devices 722a and 722b Electric Double Layer Capacitor 723 Discharging Device 723c PWM Controller 730 Fixing heaters 731 and 732 First and second fixing heaters

Claims (3)

A power storage device having a first capacitor ;
A first fixing heater that drives a fixing unit that fixes toner onto a recording sheet with electric power from an external power source; and a second fixing heater that drives the fixing unit with electric power from the power storage device;
A fixing device comprising a converter installed between the power storage device and the second fixing heater;
The power storage device has a pair of terminals configured to be capable of mounting a second capacitor ,
Said power storage device has a first state in which shorting the pair of terminals, a short-circuit state between the pair of terminals is released and and mounted between the pair of terminals of the second capacitor is the electrical storage device By this, it is comprised so that the 2nd state which supplies electric power to the said 2nd fixing heater by the series circuit of the said 1st capacitor and the 2nd capacitor can be taken ,
The converter outputs an output voltage of the power storage device so that a voltage supplied to the second fixing heater in the second state does not increase more than a voltage supplied to the second fixing heater in the first state. And a fixing device comprising output control means for keeping the voltage supplied to the second fixing heater constant . A harness for short-circuiting the pair of terminals is configured to be detachable from the pair of terminals,
The fixing device according to claim 1, wherein the power storage device is configured such that the harness and the second capacitor can be selectively attached to the pair of terminals . An image forming unit that performs an image forming operation on paper based on image data;
An image forming apparatus comprising: a fixing device according to claim 1, wherein a toner attached to the paper is fixed to the paper after the image forming operation by the image forming unit.

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