JP2012150216A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for preventing each driving element from being erroneously operated even when power source is supplied immediately after power source is turned off.SOLUTION: An image forming device comprises: a sub DC output portion in which a voltage is always output; a power source having a plurality of DC output portions of a main DC output portion capable of controlling ON and OFF of the voltage output; a main control part operated by the output from the main DC output portion; a driving circuit part for driving a plurality of driving elements operated by the output from the main DC output portion in accordance with control from the main control part; and a power source control part which controls power supply to the main control part, the driving circuit part and the driving elements and is operated by the output from the sub DC output portion. When the power source control part stops power supply to the main control part, the driving circuit part and the driving elements, the main control part controls the driving circuit part so as to drive the driving elements.

Description

  The present invention relates to an image forming apparatus that forms an image on a predetermined print medium based on image data.

  When the conventional image forming apparatus shifts from the on state to the off state, the power supply to the capacitor is stopped, and the electric charge in the capacitor is discharged through a load connected to a driving element such as each motor in the apparatus, As a result, the potential of the capacitor was lowered (see, for example, Patent Document 1).

JP 2009-58611 A (paragraph “0026”, FIG. 7)

However, in the above-described conventional technology, when the electric charge remaining in the capacitor is consumed by natural discharge when the power supply is turned off, it takes time until the discharge is completed, and in particular, the motor, fan clutch, solenoid in the apparatus The normal voltage for driving the driving element is high, and the capacitor connected for voltage smoothing has a lot of charged charge, so the discharge time becomes longer. When the power supply voltage to drive is changed from the state where it cannot completely sag to the power-on state, the voltage applied to the drive element operates before the voltage for driving the drive element rises to the voltage of the circuit that controls the drive element. In such a case, there is a possibility that the drive element may malfunction.
Also, if the discharge time is long, there is a risk that a maintenance staff may touch the base in the apparatus during the discharge and get an electric shock.
An object of the present invention is to provide means for solving the above problems.

  In order to solve the above-described problems, the present invention operates with a power supply having a sub-DC output unit that constantly outputs a voltage and a main DC output unit that can control the switching of the voltage output, and an output from the main DC output unit. A main control unit that operates according to an output from the main DC output unit and drives a plurality of drive elements under the control of the main control unit, and the main control unit, the drive from the main DC output unit A circuit unit, and a power supply control unit that controls power supply to the drive element and operates according to an output from the sub DC output unit, wherein the main control unit is configured so that the power supply control unit receives power from the main DC output unit. Control is performed so that the drive element is driven via the drive circuit section when the output is cut off.

As a result, the present invention can shorten the discharge time after the power is turned off, and can prevent the drive circuit from malfunctioning even if the power is turned on immediately after the power is turned off. can get.
In addition, it is possible to prevent maintenance personnel from touching the circuit during the discharge after the power is turned off.

Schematic diagram showing mechanism of image forming apparatus of embodiment 1 1 is a block diagram illustrating an image forming apparatus according to a first exemplary embodiment. Explanatory drawing which shows the example of a drive circuit by a drive circuit part Explanatory drawing showing an example of a capacitor Explanatory drawing which shows the power-off sequence of Example 1. FIG. 3 is a block diagram illustrating an image forming apparatus according to a second embodiment. Explanatory drawing which shows the power-off sequence of Example 2.

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram illustrating a mechanism of the image forming apparatus according to the first exemplary embodiment.
In FIG. 1, reference numeral 1 denotes an image forming apparatus.
Reference numeral 2 denotes a paper cassette having a stacking bottom surface for storing a plurality of print sheets as print media in a stacked state.

Reference numeral 3 denotes a paper feeding unit, which is a pickup roller 3a arranged so as to be pressed against the printing paper raised to a certain height, and a feed roller 3b arranged downstream of the pickup roller 3a along the direction of feeding the printing paper. The printing paper accumulated in the paper cassette 2 is separated and fed out one by one.
Here, the paper cassette 2 includes a mechanism for lifting the bottom surface by an elastic material such as a spring, so that the uppermost printing paper accumulated on the bottom surface is pressed against the pickup roller 3a.

Reference numeral 4 denotes a paper conveyance path, in which a plurality of two conveyance roller pairs 5 are arranged along the conveyance path, and the printing paper fed by the paper feeding unit 3 is nipped and conveyed by the conveyance roller pair 5.
Reference numeral 6 denotes a registration roller, which is a pair of two rollers arranged along the paper conveyance path 4 for nipping and conveying the printing paper and correcting skew caused by skewing of the printing paper.

  A sheet conveying belt 7 is arranged to support the printing sheet from below at the downstream side of the registration roller 6 in the conveying direction of the printing sheet, and an endless belt is attached to the two belt rollers 8 arranged in the conveying direction. When one belt roller 8 is rotated by driving from a driving source (not shown), the entire belt rotates to convey the printing paper.

An image forming unit 9 as an electrophotographic printing mechanism adheres toner to printing paper. In this embodiment, since four colors of black, yellow, magenta, and cyan are used for printing, four image forming units are arranged, and a color print image is formed by forming and superimposing images of the respective colors.
Reference numeral 10 denotes a photosensitive drum, on which an electrostatic latent image is formed, is disposed opposite to the paper transport belt 7, and comes into contact with the transported print paper from above.

The image forming unit 9 includes the above-described photosensitive drum 10 and also includes a charging roller, an LED head, a developing device, and the like (not shown). By contacting the charging roller, the photosensitive drum 10 is charged with a negative charge at a predetermined potential. The LED head emits light from the LED toward the surface of the photosensitive drum 10 to expose the surface of the photosensitive drum 10 to generate an electrostatic latent image.
Then, toner is adhered to a portion where the electrostatic latent image of the photosensitive drum 10 is formed by the developing device.

  A transfer roller 11 is disposed on the paper transport belt 7 at a position facing the photosensitive drum 10 and has a positive charge. By sandwiching the printing paper between the photosensitive drum 10 and a portion where the toner is attached, Then, the toner having a negative charge is attracted to transfer the toner onto the printing paper to form a toner image.

  A fixing unit 12 is provided on the downstream side of the image forming unit 9 in the conveyance direction of the printing paper. The fixing roller 12a has a halogen lamp and comes into contact with the printing paper from above, and receives a pressing force toward the fixing roller 12a. A backup roller 12b that rotates in response to the fixing roller 12a, heats the fixing roller 12a by applying power to the halogen lamp, sandwiches the printing paper between the backup roller 12b and the fixing roller 12a, and The toner adhering to the printing paper is fused to the fixing roller 12a by heat to fix the toner on the printing paper.

A discharge roller 13 conveys the printing paper on which the toner is fixed by the fixing unit 12 to the discharge port 13 a and discharges the print sheet to the outside of the image forming apparatus 1.
Reference numeral 14 denotes a paper stacking unit that collects printing paper discharged from a discharge port (not shown).
A sheet reversing unit 15 is a conveyance path for inverting the front and back of the printing sheet that has passed through the fixing unit 12 and sending the sheet to the upstream side of the registration roller 6 of the sheet conveyance path 4.

A separator 16 is arranged on the downstream side of the fixing unit 12 and switches the conveyance direction so that the printing paper is conveyed to either the discharge roller 13 side or the paper reversing unit 15 side.
Reference numeral 17 denotes a paper feed motor, which is a drive source for rotating the pickup roller 3a, the feed roller 3b, the transport roller pair 5 and the registration roller 6.

Reference numeral 18 denotes a registration clutch for switching between transmission of driving force from the sheet feeding motor 17 to the registration roller 6 and interruption of the driving force.
A drum motor 19 is a drive source for rotating the photosensitive drum 10.
The drum motor 19 transmits driving to each photosensitive drum 10 via a reduction gear (not shown) in order to rotate the photosensitive drums 10 of the four image forming units 9.

A belt motor 20 is a drive source for rotating the paper transport belt 7.
A discharge motor 21 is a drive source for rotating the fixing roller 12 a and the discharge roller 13.
A separator solenoid 22 is a drive source for operating the separator 16.
An apparatus internal cooling fan 23 is disposed in the vicinity of the fixing unit 12 and is a cooling fan for keeping the inside of the apparatus below a certain temperature.

FIG. 2 is a block diagram illustrating the image forming apparatus according to the first exemplary embodiment.
In FIG. 2, reference numeral 30 denotes a power supply, which is connected to a commercial power supply as a main power supply for supplying an alternating current, converts the supplied alternating current into a direct current, and supplies power to each part.
The power source 30 is a sub DC output unit 30a that always outputs a DC current as long as power is supplied from a commercial power source, and a main DC that cuts off the output of a DC current in accordance with an instruction from a power source control unit 31 described later. An output unit 30b is provided.

Reference numeral 34 denotes a power switch, which is a switch for switching off / on of power supply from the commercial power source to the power source 30.
The power source 30 converts the supplied alternating current into a direct current having a voltage of 24V or 5V, and the direct current having a voltage of 24V is used as a power source for power system devices such as motors, fans, and high-voltage power supplies. On the other hand, a direct current having a voltage of 5 V is used as a power source for logic devices such as the power control unit 31 and the main control unit 32.

Reference numeral 31 denotes a power supply control unit which receives power supply from the sub DC output unit 30a, and supplies power from the main DC output unit 30b in accordance with an instruction from the main control unit 32 when the power switch 34 is on. Control the destination.
A main control unit 32 controls each unit in accordance with a control program stored in a storage unit (not shown), and performs image forming processing such as printing on printing paper by the image forming apparatus 1.

  Reference numeral 33 denotes a drive circuit unit that drives drive elements such as a paper feed motor 17, a registration clutch 18, a drum motor 19, a belt motor 20, a discharge motor 21, a separator solenoid 22, and a device internal cooling fan 23.

Here, FIG. 3 is an explanatory diagram showing an example of a drive circuit by the drive circuit unit, where (a) is an example of a motor drive circuit and (b) is an example of a clutch drive circuit.
The drive circuit unit 33 has a motor drive IC as shown in FIG. 3A, and receives the control signal from the outside and the power of + 24V output by the motor drive IC to drive the drum motor 19, Similarly, the paper feed motor 17, the belt motor 20, the discharge motor 21 and the like are driven.

  Further, as shown in FIG. 3B, the drive circuit unit 33 has a field effect transistor (FET) or a transistor, and is connected to the resist clutch 18 via the FET or transistor.

  A capacitor 35 as a power storage unit shown in FIG. 3A is a capacitor for stably supplying a DC voltage, which is a drive voltage, without depending on fluctuations in the drive voltage, and the power supply 30 shown in FIG. And is arranged between a line connected from the input voltage + 24V, which is a driving voltage and a DC voltage, and a line connected from the ground (0V).

  Similarly, the capacitor 36 shown in FIG. 3B is a capacitor for stably supplying the DC voltage as the drive voltage so as not to depend on the fluctuation of the drive voltage, and the drive circuit unit 33 shown in FIG. And is arranged between a line connected from the input voltage + 24V, which is a driving voltage and a DC voltage, and a line connected from the ground (0V).

  4A and 4B are explanatory diagrams showing examples of capacitors. FIG. 4A shows the operation of the current flowing from the capacitor 35 provided in the power supply 30 when the power is turned off, and FIG. 4B shows the drive circuit unit 33 provided when the power is turned off. The operation of the current flowing from the capacitor 36 is shown.

  When the power is turned off, as shown in FIGS. 4A and 4B, the electric charge stored in the capacitor 35 and the capacitor 36 flows out in the direction of the arrow. At this time, when the power is turned off as in this embodiment, driving elements such as a paper feed motor 17, a discharge motor 21, a belt motor 20, a drum motor 19, a registration clutch 18, a separator solenoid 22, and an internal cooling fan 23 are provided. 4B, for example, as shown in FIG. 4B, a drive current flows through the paper feed motor 17 that is a drive element. Will be.

The operation of the above configuration will be described.
FIG. 5 is an explanatory diagram showing a power-off sequence according to the first embodiment. FIG. 5A is a sequence when the power is turned off by a general method, and FIG. 5B is a sequence when the power is turned off according to the present embodiment. .
In the case of a general power-off sequence, when the power control unit 31 detects that the power switch 34 of the image forming apparatus 1 is pressed and receives a power-off instruction from the main control unit 32, as shown in FIG. The main DC output on / off signal is turned off.

  The main DC output unit 30b of the power supply 30 outputs a DC current at 5V (referred to as + 5V output) to the main control unit 32 according to the main DC output on / off signal being turned off, and to each drive element via the drive circuit unit 33. The output of the direct current at 24V (+ 24V output) is stopped, and the capacitor 35 as the power storage unit in the power supply 30 and the capacitor 36 in the drive circuit unit 33 are discharged by the electrostatic capacity. It takes time T1 (about 3 to 5 seconds) to discharge this charge.

  When the voltage droop due to the discharge is finished, the reset signal of the main control unit 32 is reset, and the on / off signals relating to the operation of all parts including the drum motor drive on / off signal are turned off to the initial values, and the power off sequence Ends.

Next, in the power-off sequence in this embodiment, when the depression of the power switch 34 of the image forming apparatus 1 is detected and a power-off instruction is received from the main control unit 32, the power control unit 31 is as shown in FIG. The main DC output on / off signal is turned off.
The main DC output unit 30b of the power supply 30 stops + 5V output to the main control unit 32 and + 24V output to each drive element via the drive circuit unit 33 in accordance with the main DC output on / off signal being turned off.

When the main controller 32 recognizes that the main DC output on / off signal is off, the main controller 32 outputs a drum motor drive on / off signal to drive the drum motor 19.
The drive circuit unit 33 confirms the ON output of the drum motor drive ON / OFF signal and starts driving the drum motor 19.

Here, the drum motor 19 is a drive source for rotating the photosensitive drum 10 and has a large load torque. Therefore, the drum motor 19 is a part that consumes the most power among the drive elements driven by the drive circuit unit 33.
Driving the drum motor 19 increases the consumption of electric charges for the electrostatic capacity charged in the capacitor 35 in the power supply 30 and the capacitor 36 in the drive circuit unit 33, and the discharge time is T2 (about 0.5 seconds). The voltage drooping is faster compared to the above general power-off sequence.

When the voltage droop due to the discharge is finished, the reset signal of the main control unit 32 is reset, and the on / off signals relating to the operation of all parts including the drum motor drive on / off signal are turned off to the initial values, and the power off sequence Ends.
That is, the drum motor 19 is driven and discharged forcibly until the voltage drops after the main DC output on / off signal is turned off and the reset signal of the main control unit 32 is in the reset state.

  The reason why the discharge time is shortened at this time is that the static friction resistance of a reduction gear (not shown) arranged for driving the photosensitive drum 10 is large. Further, since there is a frictional resistance, the photosensitive drum 10 does not rotate during discharge.

  Since the time T2 required for discharging the charged electric charge is shortened as the electric power consumed is increased, the paper feed motor 17, the registration clutch 18, the belt motor 20, the discharge motor 21 and the separator solenoid are used together with the drum motor 19. Drive elements such as 22 and the device internal cooling fan 23 may be driven.

As described above, in this embodiment, the drum motor, which is indispensable for the operation of the image forming apparatus, is driven when the power is turned off, thereby increasing the consumption of the electric charge charged in the capacitor, so Since it is possible to forcibly discharge without adding a circuit, even if the power is turned on immediately after the power is turned off, each part can be operated from a state in which the voltage drops completely. Can be prevented.
Further, since the discharge time is shortened, it is possible to prevent the maintenance staff from touching the base in the apparatus and receiving an electric shock.

FIG. 6 is a block diagram illustrating an image forming apparatus according to the second embodiment.
In addition, the same part as the said Example 1 attaches | subjects the same code | symbol, and abbreviate | omits the description.
The present embodiment is different from the first embodiment in that a voltage monitoring unit 40 is newly provided in the power supply control unit 31.
The voltage monitoring unit 40 in FIG. 6 monitors the voltage of the power output from the main DC output unit 30b.

A power-off sequence in the configuration described above will be described.
FIG. 7 is an explanatory diagram illustrating a power-off sequence according to the second embodiment.
When the power control unit 31 detects that the power switch 34 of the image forming apparatus 1 is pressed and receives a power off instruction from the main control unit 32, the power control unit 31 turns off the main DC output on / off signal as shown in FIG.

The main DC output unit 30 b of the power supply 30 stops +5 V output to the main control unit 32 and +24 V output to each drive element via the drive circuit unit 33 in accordance with the main DC output on / off signal being turned off.
When the main control unit 32 detects that the main DC output on / off signal is off, the main control unit 32 drives the drum motor 19 that consumes the most power among the drive elements connected to the drive circuit unit 33. Outputs on.

  The power supply control unit 31 confirms the + 24V output voltage output from the main DC output unit 30b by the voltage monitoring unit 40 after a predetermined time Ts has elapsed since the main DC output on / off signal is turned off. When the voltage is not completed and the voltage is equal to or higher than a certain value, the main controller 32 is notified of an operation start instruction for another part.

When the main control unit 32 receives the notification of the operation start instruction, the main control unit 32 outputs, in addition to the drum motor 19, other drive elements, here, a registration clutch drive on / off signal.
The drive circuit unit 33 drives the registration clutch 18 when the registration clutch drive on / off signal is turned on.
Driving the registration clutch 18 in addition to the drum motor 19 increases the consumption of charged electrostatic charge.

When the reset signal of the main control unit 32 is reset due to the voltage drop, the drum motor drive on / off signal and the registration clutch drive on / off signal are also turned off to the initial values, and the drum motor 19 and the registration clutch 18 are also driven. Stop.
That is, when the voltage is equal to or higher than a certain voltage even after a predetermined time Ts has elapsed since the main DC output on / off signal is turned off, the driving elements other than the drum motor 19 are additionally driven to accelerate the discharge.
Note that the time T3 required for discharging the charged electric charge is shortened as the consumed electric power is increased. Therefore, a plurality of other driving elements to be additionally driven may be simultaneously driven.

As described above, in this embodiment, in addition to the effects of the first embodiment, when the power is turned on immediately after the power is turned off, the malfunction of the drive circuit unit can be prevented more stably.
The image forming apparatus in each of the above embodiments has been described as an ink jet printer. However, the present invention is not limited to this, and the same effect can be obtained by using a copying machine, a facsimile machine, or a composite machine as an image forming apparatus.
Also, other than the image forming apparatus, the same effect can be obtained even if the same functional block configuration is used for a general electric device.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper cassette 3 Paper feeding part 3a Pickup roller 3b Feed roller 4 Paper conveyance path 5 Conveyance roller pair 6 Registration roller 7 Paper conveyance belt 8 Belt roller 9 Image forming unit 10 Photosensitive drum 11 Transfer roller 12 Fixing unit 12a Fixing Roller 12b Backup roller 13 Discharge roller 13a Discharge port 14 Paper stacking part 15 Paper reversing part 16 Separator 17 Paper feed motor 18 Registration clutch 19 Drum motor 20 Belt motor 21 Discharge motor 22 Separator solenoid 23 Internal cooling fan 30 Power supply 30a Sub DC output Unit 30b Main DC output unit 31 Power supply control unit 32 Main control unit 33 Drive circuit unit 34 Power switch 35 Capacitor 36 Capacitor 40 Voltage monitoring unit

Claims (2)

A power supply having a sub DC output unit that constantly outputs a voltage and a main DC output unit that can control the switching of the voltage output;
A main control unit that operates according to an output from the main DC output unit;
A drive circuit unit that operates according to an output from the main DC output unit and drives a drive element under the control of the main control unit;
A power control unit that controls power supply from the main DC output unit to the main control unit, the drive circuit unit, and the drive element, and operates according to an output from the sub DC output unit,
The image forming apparatus according to claim 1, wherein the main control unit controls the drive element to be driven via the drive circuit unit when the power supply control unit cuts off the output from the main DC output unit. The image forming apparatus according to claim 1.
A voltage monitoring unit that is controlled by the voltage control unit and monitors a voltage output from the main DC output unit;
The main control unit is configured to notify the main control unit when the voltage monitored by the voltage monitoring unit is equal to or higher than a predetermined value after a predetermined time has elapsed since the power supply was stopped. To
When the main control unit receives the notification, the main control unit drives other driving elements in addition to the driving elements already driven.

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