JP4696726B2 - Electronics - Google Patents

Description

  The present invention relates to an electronic device including a plurality of electrical components that receive power from a single power source, and more particularly to an electronic device that takes into account stabilization of the power supply voltage of the power source.

  Conventionally, as a DC power source for various electronic devices such as laser printers, for example, a relatively low voltage (eg, 3.3V) stabilized control system output for supplying power to a CPU or the like, a printer engine, a fan, etc. In some cases, a power supply having a drive system output with a relatively high voltage (for example, 24 V) for supplying power to a plurality of electrical components may be used. In addition, as this type of power supply, a switching power supply including a single transformer having the control system output and the drive system output on the secondary side may be used.

With this type of power supply, when the drive system output load is small and the control system output load is large, the drive system output voltage will increase if an attempt is made to stabilize the control system output voltage. There is. Therefore, in such a case, it has been proposed to increase the load of the drive system output by driving a load such as a fan to suppress the voltage increase of the drive system output (see, for example, Patent Document 1). ).
JP 11-196574 A

  However, the above-described technique cannot cope with a case where the load of the drive system output suddenly increases and the output voltage decreases, and the voltage of the drive system output may fluctuate greatly. Moreover, not only the power source having two outputs for the control system and the drive system as described above, but when a plurality of electrical components are supplied with power from one power source, one electrical component is driven. The voltage may fluctuate as the load increases. Therefore, the present invention favorably suppresses fluctuations in the power supply voltage even when any of the plurality of electrical components is driven in an electronic device including a plurality of electrical components that receive power supply from a single power source. It was made for the purpose.

The present invention made to achieve the above object is an electronic device including a solenoid that receives power supply from one power source and a plurality of cooling fans , and a current that flows through the solenoid when the solenoid is driven. At the timing of canceling out the transient fluctuations of the current and the transient fluctuations of the current flowing through the cooling fans, the plurality of cooling fans being driven at that time are sequentially stopped and the driving of the solenoid is stopped. In this case, drive control means for re-driving the plurality of cooling fans is provided.

In the present invention configured as described above, when the drive control unit drives the solenoid that receives power supply from one power source and the solenoid among the plurality of cooling fans , the plurality of cooling units that are being driven at that time are driven. The cooling fan is sequentially stopped at a timing at which the transient fluctuation of the current flowing through the solenoid and the transient fluctuation of the current flowing through the cooling fans cancel each other . For this reason, an increase in the load due to the driving of the solenoid and a decrease in the load due to the stop of the driving of each cooling fan cancel each other, and the fluctuation of the load on the one power source can be suppressed. Further, the drive control means re-drives the plurality of cooling fans when stopping the driving of the solenoid . For this reason, a decrease in load due to the stop of driving of the solenoid and an increase in load due to driving of the cooling fans cancel each other, and in this case as well, fluctuations in the load on the one power source can be suppressed. As described above, in the electronic apparatus of the present invention, it is possible to suppress the fluctuation of the load with respect to the one power supply and to satisfactorily suppress the fluctuation of the power supply voltage.

In addition, the cooling fan does not affect the main operation of the electronic device even if the drive / stop is temporarily switched. Therefore, in the present invention, fluctuations in the power supply voltage can be suppressed without affecting the main operation of the electronic device. Further, since the solenoid is a relatively large load, the effect of suppressing the load variation as described above Ru appear even more pronounced.

Furthermore, (increase in current) load increase when driving the solenoid whereas is the relatively slow, (decrease in the current) load reduction when shutting down the cooling fan is relatively steep. For this reason, if a plurality of cooling fans are sequentially stopped at the above timing when the solenoid is driven, the increase and decrease of the load can be offset more favorably, and the fluctuation of the load as a whole can be further suppressed. Can do. Therefore, in this case, fluctuations in the power supply voltage can be suppressed more satisfactorily.

Furthermore, the upper Symbol electronic apparatus is an image forming apparatus having an image forming means for forming an image on a recording medium, the solenoid, in order to switch the supply / non-supply of the recording medium to said image forming means It may be.

  Next, embodiments of the present invention will be described with reference to the drawings. As described below, the present embodiment is an application of the present invention to a so-called laser printer as an image forming apparatus.

1. FIG. 1 is a perspective view showing the appearance of a laser printer 1 according to the present embodiment. The laser printer 1 is installed with the upper side of the paper as the upper side in the direction of gravity, and usually the left front side of the paper is the front side. Used as.

  The housing 3 of the laser printer 1 is formed in a substantially box shape (a rectangular parallelepiped shape), and a recording medium discharged from the housing 3 after printing is placed on the upper surface side of the housing 3. A paper discharge tray 5 is provided. In the present embodiment, paper such as paper or an OHP sheet is assumed as the recording medium.

  Further, the paper discharge tray 5 is configured with an inclined surface 5a that is inclined so as to descend from the upper surface of the housing 3 toward the rear side, and printing is finished on the rear end side of the inclined surface 5a. A discharge unit 7 for discharging the recording medium is provided.

  The upper cover 9 formed in a substantially U-shape so as to surround the paper discharge tray 5 (inclined surface 5a) in the casing 3 includes a case where the laser printer 1 is connected to the network and a case where the laser printer 1 is disconnected from the network. Are provided, a line switch 1a for switching, a job cancel switch 1b for forcibly ending (interrupting) printing, and the like.

2. Internal Configuration of Laser Printer FIG. 2 is a longitudinal sectional view showing the internal configuration of the laser printer 1. The image forming unit 10 accommodated in the laser printer 1 constitutes an image forming unit that forms an image on a recording medium, and the feeder unit 20 is a conveying unit that supplies the recording medium to the image forming unit 10. It constitutes a part of

  The first discharge chute 30 and the second discharge chute 40 are turned approximately 180 ° so as to make a U-turn in the transport direction of the recording medium on which image formation has been completed in the image forming unit 10, and the recording medium is fixed to the fixing unit. It constitutes a guide member that guides to a discharge portion 7 provided above 90 (details will be described later).

  The forward / reverse switching mechanism 50 reverses the transport direction of the recording medium ejected from the image forming unit 10 and simultaneously discharges the recording medium whose transport direction is reversed to the image forming unit 10 side. The double-sided printing unit 60 constitutes a conveyance path for a recording medium whose conveyance direction is reversed by the forward / reverse switching mechanism 50.

2.1. Feeder unit The feeder unit 20 includes a paper feed tray 21 housed in the lowermost part of the housing 3, a paper feed roller 22 that is provided above the front end of the paper feed tray 21 and transports a recording medium to the image forming unit 10, In addition, the image forming apparatus includes a separation roller 23 and a separation pad 24 that separate the recording medium conveyed by the paper feeding roller 22 one by one. Then, the recording medium placed on the paper feed tray 21 is conveyed to the image forming unit 10 disposed substantially at the center in the housing 3 so as to make a U-turn on the front side in the housing 3. Is done.

  In addition, in the conveyance path of the recording medium from the paper feed tray 21 to the image forming unit 10, the image forming surface (printing surface) of the recording medium is attached to the outside of the top portion of the portion that turns in a substantially U shape. A paper dust removing roller 25 that removes paper dust and the like is disposed, and a counter roller 26 that presses the recording medium to be conveyed against the paper dust removing roller 25 is disposed inside the top portion.

  Further, at the entrance of the image forming unit 10 in the transport path from the paper feed tray 21 to the image forming unit 10, a resist composed of a pair of rollers that applies a transport resistance to the recording medium and adjusts the transport state of the recording medium. A roller 27 is provided.

2.2. Image Forming Unit The image forming unit 10 includes a scanner unit 70, a process cartridge 80, a fixing unit 90, and the like.

2.2.1. Scanner Unit The scanner unit 70 is provided on the upper portion of the housing 3 and forms an electrostatic latent image on the surface of a photosensitive drum 81 described later. A polygon driven by a laser light source (not shown) and a polygon motor 450. A mirror 72, an fθ lens 73, a reflecting mirror 74, a lens 75, and a reflecting mirror 76 are included.

  Then, the laser beam based on the image data emitted from the laser light source is deflected by the polygon mirror 72, passes through the fθ lens 73, the optical path is turned back by the reflecting mirror 74, and further passes through the lens 75, and then reflected. When the optical path is bent downward by the mirror 76, the surface of the photosensitive drum 81 is irradiated and an electrostatic latent image is formed.

2.2.2. Process Cartridge The process cartridge 80 is detachably disposed in the housing 3 below the scanner unit 70. The process cartridge 80 includes a photosensitive drum 81, a charger 82, a transfer roller 83, and a development roller. It is composed of a cartridge 84 and the like.

  The photoconductive drum 81 extends along the longitudinal direction of the drum main body 81a at a cylindrical drum main body 81a formed by a positively chargeable photosensitive layer whose outermost layer is made of polycarbonate or the like, and the axis of the drum main body 81a. And a drum shaft 81b that rotatably supports the drum body 81a.

  The charger 82 charges the surface of the photosensitive drum 81 prior to the formation of the electrostatic latent image by the laser beam. The charger 82 is predetermined so as not to come into contact with the photosensitive drum 81 at the upper rear side of the photosensitive drum 81. The photosensitive drum 81 is disposed opposite to the photosensitive drum 81 with a gap. The charger 82 according to the present embodiment employs a scorotron charger that charges the surface of the photosensitive drum 81 substantially uniformly with positive charges using corona discharge.

  The transfer roller 83 is disposed so as to face the photosensitive drum 81 and rotates in conjunction with the rotation of the photosensitive drum 81, and when the recording medium passes near the photosensitive drum 81, the transfer roller 83 is attached to the photosensitive drum 81. By applying a charge opposite to the charged charge (in this embodiment, a negative charge) to the recording medium from the side opposite to the printing surface, the toner attached to the surface of the photosensitive drum 81 is printed on the recording medium. It constitutes a transfer means for transferring to the surface.

  The developing cartridge 84 includes a toner storage chamber 84a that stores toner, a toner supply roller 84b that supplies the toner to the photosensitive drum 81, a developing roller 84c, and the like.

  The toner stored in the toner storage chamber 84a is supplied to the developing roller 84c side by the rotation of the toner supply roller 84b. Further, the toner supplied to the developing roller 84c is carried on the surface of the developing roller 84c, adjusted to have a predetermined thickness by the layer thickness regulating blade 84d and frictionally charged, and then in the scanner unit 70. The exposed surface of the photosensitive drum 81 is supplied.

2.2.3. Fixing Unit The fixing unit 90 is disposed downstream of the photosensitive drum 81 in the recording medium conveyance direction, and heats and melts the toner transferred to the recording medium for fixing. Specifically, the fixing unit 90 is disposed on the printing surface side of the recording medium to heat the toner, and is disposed on the opposite side of the heating roller 91 across the recording medium. A pressure roller 92 that presses the recording medium toward the heating roller 91 is provided.

  Incidentally, the heating roller 91 according to the present embodiment is composed of a metal tube whose surface is coated with a fluororesin, and a halogen lamp for heating in the metal tube. The metal roller shaft is covered with a roller made of a rubber material.

In the image forming unit 10 described above, an image is formed on a recording medium as follows.
In other words, the surface of the photosensitive drum 81 is uniformly positively charged by the charger 82 as it rotates, and then exposed by high-speed scanning of the laser beam emitted from the scanner unit 70. As a result, an electrostatic latent image corresponding to the image to be formed on the recording medium is formed on the surface of the photosensitive drum 81.

  Next, when the developing roller 84c rotates, the positively charged toner carried on the developing roller 84c is formed on the surface of the photosensitive drum 81 when it contacts the photosensitive drum 81. Of the electrostatic latent image, that is, the surface of the uniformly positively charged photosensitive drum 81, is supplied to the exposed portion where the potential is lowered by the laser beam. As a result, the electrostatic latent image on the photosensitive drum 81 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 81.

  Thereafter, the toner image carried on the surface of the photosensitive drum 81 is transferred to a recording medium by a transfer bias applied to the transfer roller 83. The recording medium to which the toner image has been transferred is conveyed to the fixing unit 90 and heated, and the toner transferred as the toner image is fixed to the recording medium, thereby completing the image formation.

2.3. First Discharge Chute In the laser printer 1 according to the present embodiment, the first discharge chute 30 is disposed on the rear end side in the housing 3 as shown in FIG. On the side, that is, in the vicinity of the first discharge chute 30, a rear cover 3b that opens and closes an opening 3a formed in the housing 3 is rotatably assembled.

  The first discharge chute 30 is disposed downstream of the fixing unit 90 in the transport direction in the transport direction of the recording medium, and the transport direction of the recording medium in which image formation has been completed in the image forming unit 10. Is rotated approximately 90 ° to guide the recording medium to the second discharge chute 40.

  The first discharge chute 30 is disposed on the downstream side in the recording medium conveyance direction from the front chute 31 disposed at a portion where the recording medium discharged from the fixing unit 90 first contacts, and the front chute 31. The outer chute 32 is provided. Each of the front chute 31 and the outer chute 32 is formed with a plurality of protruding front chute ribs 31a and outer chute ribs 32a extending along the recording medium conveyance direction. The ribs 31a and 32a are guided toward the second discharge chute 40 while being in contact with the leading ends of the ribs 31a and 32a. Further, the first discharge chute 30 is provided with a first paper discharge roller 34a, and a first pinch roller 34b is provided at a position facing the first paper discharge roller 34a on the fixing unit 90 side.

  The first paper discharge roller 34a is a transport roller that applies a transport force to the recording medium by rotating while contacting the recording medium, and the first pinch roller 34b is a first paper discharge sandwiching the recording medium. The recording medium is pressed toward the first paper discharge roller 34a from the side opposite to the roller 34a. For this reason, the recording medium discharged from the fixing unit 90 is conveyed to the second discharge chute 40 side so as to be sandwiched between the first discharge roller 34a and the first pinch roller 34b.

2.4. Second discharge chute The second discharge chute 40 is provided on the upper cover 9 with a predetermined gap 40a with respect to the first discharge chute 30, and the conveying direction is turned by approximately 90 ° by the first discharge chute 30. The recording medium is further turned by approximately 90 ° and guided to the discharge unit 7.

  Further, a gap 40a between the first discharge chute 30 and the second discharge chute 40 is a recording medium conveyance path (conveyance path indicated by a thick two-dot chain line) whose conveyance direction is reversed by the forward / reverse switching mechanism 50. Part of. Incidentally, in FIG. 2, a transport path indicated by a thick one-dot chain line indicates a transport path of a recording medium transported by the feeder unit 20.

2.5. Forward / reverse switching mechanism and double-sided printing unit The forward / reverse switching mechanism 50 switches the direction of rotation of the second paper discharge roller 43, thereby discharging the recording medium conveyed from the first discharge chute 30 to the discharge unit 7 (paper discharge). The case of transporting to the tray 5) side and the case of transporting to the gap 40a side are switched. For example, the forward / reverse switching mechanism 50 uses a solenoid (not shown) to switch the number of gears that transmit a rotational force generated by a DC motor 440 (see FIG. 4), which will be described later, to the second paper discharge roller 43 to perform the second paper discharge. This is a mechanism for switching the rotation direction of the roller 43. The second pinch roller 43b disposed opposite to the second paper discharge roller 43 rotates in a manner to sandwich the recording medium in cooperation with the second paper discharge roller 43, so that the second recording roller and the second recording roller 43b are rotated. The contact surface pressure with the paper discharge roller 43 is increased.

  The duplex printing unit 60 has a plurality of guide ribs (not shown) formed in a protruding shape so as to extend in the conveyance direction (front-rear direction) of the recording medium, and contacts the recording medium while rotating. A plurality of rollers (not shown) for applying a conveyance force to the recording medium are provided, and the recording medium conveyed from the second paper discharge roller 43 through the gap 40a is conveyed to the image forming unit 10. .

2.6. Power Supply Unit A power supply unit 100 that supplies power to each unit of the laser printer 1 is disposed between the fixing unit 90 and the duplex printing unit 60. Next, the configuration of the power supply unit 100 will be described with reference to the circuit diagram of FIG. In addition, the power supply unit 100 is configured to simultaneously supply a voltage (24V in the present embodiment) supplied to various motors and the like and a voltage (3.3V in the present embodiment) supplied to a logic circuit that controls each unit. Output.

  As shown in FIG. 3, the power supply unit 100 includes, on the primary side of the transformer 200, a rectifier circuit 120 that rectifies current supplied from a commercial power supply 110 (AC100V), a smoothing capacitor 130, and a transformer 200. A switching element 140 that switches energization to the primary coil and an oscillation control circuit 150 that controls ON / OFF of the switching element 140 are provided.

  The oscillation control circuit 150 constitutes a photocoupler together with a secondary side photodiode 161 described later, and internally includes a phototransistor 160 that is turned on / off by receiving light emitted from the photodiode 161. In the present embodiment, the oscillation control circuit 150 assumes a self-excited configuration in which the switching element 140 oscillates at an oscillation frequency defined by ON / OFF of the phototransistor 160. A separately-excited configuration that controls the energization time to the primary side of the transformer 200 may be used. In the present embodiment, a flyback in which energy is accumulated in the transformer 200 when the switching element 140 is turned on and an electromotive force is generated on the secondary side when the switching element 140 on the primary side is turned off. The configuration of the method was adopted.

  On the secondary side of the transformer 200, a first output line 311 that outputs a voltage of 24V via a rectifier element 310 and a second output line 313 that outputs a voltage of 3.3V via a rectifier element 312 are provided. It has been. Since the voltage of 3.3V output to the second output line 313 is supplied to the logic circuit or the like as described above, it needs to be stabilized. Therefore, in the power supply unit 100, a photodiode 161 is connected between the second output line 313 and the ground line 314, and the output voltage of the second output line 313 is obtained by the photodiode 161 and the phototransistor 160 that constitutes the photocoupler. Feedback to the primary side.

  The photodiode 161 is turned on when the output of the second output line 313 becomes higher than a predetermined value and the shunt regulator 321 becomes conductive from the second output line 313 to the ground line 314. Note that the voltage of the second output line 313 at which the shunt regulator 321 becomes conductive can be finely adjusted by the variable resistor 330. In the self-excited type as in the present embodiment, when the photodiode 161 is lit, the oscillation frequency of the switching element 140 is increased, the amount of energization on the primary side of the transformer 200 is decreased, and the voltage on the secondary side is decreased. Is feedback controlled. On the other hand, when the voltage of the second output line 313 decreases, the photodiode 161 is turned off and the energization amount on the primary side increases.

2.7. As shown in FIGS. 1 and 2, the laser printer 1 further includes a main fan 410 that cools the entire image forming unit 10 around the fixing unit 90 as a cooling fan. And a PS fan 420 that cools the power supply unit 100. As shown in FIG. 4, the main fan 410 and the PS fan 420 are connected to an ASIC (application specific integrated circuit) 500 incorporating a CPU together with a solenoid 430, a DC motor 440, and a polygon motor 450. Yes. Note that the solenoid 430 shown in FIG. 4 switches whether or not the rotational force generated by the DC motor 440 is transmitted to the paper feed roller 22. In addition, the main fan 410, the PS fan 420, the solenoid 430, the DC motor 440, the polygon motor 450, and the like are supplied with power from the first output line 311 of the power supply unit 100.

  As shown in FIG. 4, the ASIC 500 is connected to the main fan 410 via the main fan drive circuit 411, and determines whether or not the aforementioned 24V is supplied to the main fan 410 via the main fan drive circuit 411. Switch. Similarly, the ASIC 500 is connected to the PS fan 420 via the PS fan drive circuit 421, and switches whether or not the aforementioned 24V is energized to the PS fan 420 via the PS fan drive circuit 421. Further, the ASIC 500 is connected to the solenoid 430 via the solenoid drive circuit 431, and switches whether or not the aforementioned 24V is energized to the solenoid 430 via the solenoid drive circuit 431.

  The ASIC 500 is connected to a DC motor 440 via a DC motor drive circuit 441, and a D / A conversion circuit 442 is also connected between the DC motor drive circuit 441 and the ASIC 500. The ASIC 500 directly inputs an ON / OFF signal for switching whether or not the aforementioned 24 V is supplied to the DC motor 440 to the DC motor drive circuit 441, while a PWM signal as a drive current control signal for the DC motor 440 is The signal is input to the DC motor drive circuit 441 through the D / A conversion circuit 442. Similarly, the ASIC 500 is connected to the polygon motor 450 via a polygon motor drive circuit 451, and a D / A conversion circuit 452 is also connected between the polygon motor drive circuit 451 and the ASIC 500. The ASIC 500 directly inputs an ON / OFF signal for switching whether or not to energize the aforementioned 24V to the polygon motor 450 to the polygon motor drive circuit 451, while receiving a PWM signal as a drive current control signal for the polygon motor 450, The data is input to the polygon motor drive circuit 451 via the D / A conversion circuit 452.

  The DC motor 440 is connected to a DC motor speed detection circuit 443 that detects the rotation speed, and the detection result is input to the ASIC 500. Further, the DC motor drive circuit 441 is connected to a DC motor drive current detection circuit 444 that detects the energization current, and the detection result is input to the ASIC 500. Similarly, a polygon motor speed detection circuit 453 is connected to the polygon motor 450, and a polygon motor drive current detection circuit 454 is connected to the polygon motor drive circuit 451. The detection results are input to the ASIC 500, respectively.

3. Control in Laser Printer of Embodiment Next, control executed by the ASIC 500 will be described. The ASIC 500 appropriately switches ON / OFF of the solenoid 430 in order to switch supply / non-supply of the recording medium according to the image forming process. Since this process is well known, description thereof is omitted here. The ASIC 500 switches ON / OFF of the main fan 410 and the PS fan 420 as follows in accordance with ON / OFF of the solenoid 430.

  FIG. 5 is a timing chart showing the control of the ASIC 500 according to ON / OFF of the solenoid 430 and the current change caused thereby. In FIG. 5, FAN1 represents the main fan 410, and FAN2 represents the PS fan 420.

  As shown in FIG. 5, the ASIC 500 normally drives both the main fan 410 and the PS fan 420 at full speed. When the solenoid 430 is turned on at time t1, the main fan 410 is simultaneously driven at 35% of the full speed. At the subsequent time t2, the PS fan 420 is driven at 45% of the full speed, at the time t3, the PS fan 420 is stopped, and at the subsequent time t4, the main fan 410 is stopped. Further, when the ASIC 500 turns off the solenoid 430 at time t5, the main fan 410 and the PS fan 420 are simultaneously driven.

  By such control of the ASIC 500, the solenoid current flowing through the solenoid 430, the FAN1 current flowing through the main fan 410, the FAN2 current flowing through the PS fan 420, and the 24V current and 24V output from the first output line 311 of the power supply unit 100. The voltage changes as follows.

  That is, the solenoid current rises at time t1, increases relatively slowly, and continues to increase until a little later than time t4. At this time, the FAN1 current decreases stepwise at time t1 and time t4, and the FAN2 current decreases stepwise at time t2 and time t3, respectively, and the decrease at each time is relatively steep. For this reason, the increase in the solenoid current and the decrease in the FAN1 current and the FAN2 current from the time t1 to the time t4 cancel each other, and the fluctuation of the 24V current is suppressed. For this reason, the fluctuation | variation of 24V voltage is suppressed and the fluctuation | variation of the rotation speed (motor rotation speed) of the DC motor 440 can also be suppressed.

  The solenoid current decreases relatively steeply at time t5 and stabilizes at time t6. At this time, the FAN1 current and the FAN2 current simultaneously increase at time t5, and the increase is relatively steep, so that the decrease in the solenoid current and the increase in the FAN1 current and the FAN2 current cancel each other, and the 24V current and 24V voltage It is possible to suppress the fluctuation of the motor rotation speed by suppressing the fluctuation.

  Thus, in the present embodiment, the fluctuation of the 24V voltage can be satisfactorily suppressed by canceling the fluctuation of the solenoid current and the fluctuation of the FAN1 current and the FAN2 current. For this reason, the fluctuation | variation of the rotation speed (motor rotation speed) of DC motor 440 can be suppressed, and stable image formation can be performed. Note that the bottom row of FIG. 5 shows fluctuations in the motor rotation speed in the conventional example in which the main fan 410 and the PS fan 420 are continuously driven at full speed regardless of whether the solenoid 430 is ON / OFF. By comparing with this conventional example, it can be seen that in the present embodiment, fluctuations in the motor rotation speed can be suppressed very well.

  In addition, in the present embodiment, the current is canceled by using the main fan 410 and the PS fan 420, and these fans do not affect the main operation of the laser printer 1 even if the driving is temporarily stopped. Absent. Therefore, in this embodiment, fluctuations in the 24V current and the 24V voltage can be suppressed without affecting the main operation of the laser printer 1.

  In the above embodiment, the solenoid 430 corresponds to the first electrical component, the main fan 410 and the PS fan 420 correspond to the other electrical components, and the ASIC 500 corresponds to the drive control means. The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, as the first electrical component and other electrical components, various forms other than the above can be considered.

4). Other Embodiments of the Present Invention FIG. 6A shows that an ASIC 500 is connected to a solenoid 430 (corresponding to a first electrical component) via a solenoid drive circuit 431 whose main part is a transistor. In this example, a capacitor 460 (corresponding to another electrical component) is connected via a capacitor driving circuit 461 whose main part is. In this embodiment, the ASIC 500 can switch whether or not to apply 24V to the solenoid 430 via the solenoid driving circuit 431 and can switch charging / discharging of the capacitor 460 via the capacitor driving circuit 461.

  In this case, when the transistor of the capacitor driving circuit 461 is turned on and the capacitor 460 is maintained in a discharged state, a certain amount of current flows through the resistors 462 and 463. When the transistor of the capacitor driving circuit 461 is turned off and the capacitor 460 is charged, the amount of current gradually decreases to zero, and when the capacitor 460 is discharged, the amount of current increases rapidly and reaches the above-mentioned constant amount.

  Therefore, as shown in FIG. 6B, the ASIC 500 switches the capacitor 460 from the discharged state to the charged state at the same time as turning on the solenoid 430, and switches the capacitor 460 from the charged state to the discharged state at the same time as turning off the solenoid 430. Then, the solenoid current flowing through the solenoid 430 and the charge / discharge current flowing through the pull-up resistor 463 of the capacitor 460 just cancel each other, and the motor rotation speed can be kept constant. Furthermore, the present invention can be applied to electronic devices other than the image forming apparatus.

1 is a perspective view illustrating an appearance of a laser printer to which the present invention is applied. It is a longitudinal cross-sectional view showing the internal structure of the laser printer. It is a circuit diagram showing the structure of the power supply unit of the laser printer. It is a block diagram showing the structure of the control system of the laser printer. It is a timing chart showing the control by the control system, and the electric current change by the control. It is a timing chart showing the structure of the control system of other embodiment, and the electric current change according to control by the control system.

DESCRIPTION OF SYMBOLS 1 ... Laser printer 10 ... Image formation part 20 ... Feeder part 22 ... Feed roller 70 ... Scanner part 72 ... Polygon mirror 80 ... Process cartridge 81 ... Photoconductor drum 90 ... Fixing unit 100 ... Power supply unit 140 ... Switching element 150 ... Oscillation control circuit 160 ... Phototransistor 161 ... Photodiode 200 ... Transformer 311 ... First output line 313 ... Second output line 410 ... Main fan 411 ... Main fan drive circuit 420 ... PS fan 421 ... PS fan drive circuit 430 ... Solenoid 431 ... Solenoid drive circuit 440 ... DC motor 441 ... DC motor drive circuit 442 ... D / A conversion circuit 443 ... DC motor speed detection circuit 444 ... DC motor drive current detection circuit 450 ... Polygon motor 451 ... Polygon motor drive Circuit 452 D / A conversion circuit 454 Polygon motor drive current detection circuit 460 Capacitor 461 Capacitor drive circuit

Claims (2)

An electronic device including a solenoid that receives power from one power source and a plurality of cooling fans ,
When the solenoid is driven, the plurality of cooling units that are being driven at the time when the transient variation of the current flowing through the solenoid and the transient variation of the current flowing through the cooling fans cancel each other. Drive control means for sequentially stopping the fan and re-driving the plurality of cooling fans when stopping the driving of the solenoid ;
Electronic equipment characterized by comprising. The electronic apparatus is an image forming apparatus including an image forming unit that forms an image on a recording medium,
2. The electronic apparatus according to claim 1 , wherein the solenoid is for switching supply / non-supply of the recording medium to the image forming unit .