JP2007298834A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing the fluctuation of power source voltages without voltage conversion from alternating current voltage to direct current voltage. <P>SOLUTION: The image forming apparatus having a heating means in which a supplied electric power value is variable is provided with a main body control part which detects the present fixation electric power value W<SB>h0</SB>of a heating means, calculates a difference value ΔW between the detected present fixation electric power value W<SB>h0</SB>and a fixation target output value W<SB>hN</SB>to be supplied to the heating means, sets the change rate α of the electric power supplied to the heating means on the basis of the calculated difference value ΔW and a change rate table stored in a storage part and controls the electric power value supplied to the heating means in accordance with the set changing rate α. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a component such as a heating unit in which a power value to be supplied is variable.

  In recent years, an image forming apparatus such as an electrophotographic copying machine, a facsimile, a printer, or a complex machine thereof forms a toner image based on image data on a recording medium, and uses the recording medium on which the toner image is formed as a fixing device. The unfixed toner image on the recording medium is heated and fixed by a feeding and fixing device to obtain a printed image.

  The fixing device provided in the image forming apparatus includes a heating unit such as a heater capable of adjusting power supplied to control the fixing temperature. A phase control method using an AC voltage is used for power control for the heating means. However, this phase control method has a problem in that an increase in high-frequency current and fluctuation in power supply voltage (flicker) increase.

Therefore, the AC voltage supplied to the radiant heater (heating means) is converted into a DC voltage, and the maximum power value consumed by the radiant heater and the maximum control voltage value of the DC voltage are determined based on the system configuration of the image forming apparatus. An image forming apparatus is disclosed that calculates a control voltage within a range of a maximum control voltage value and varies a DC voltage assigned to a radiant heater (see Patent Document 1).
JP 2004-240250 A

  However, the conventional image forming apparatus as in Patent Document 1 has to convert AC voltage to DC voltage, which causes a problem that the apparatus configuration is increased in size and cost.

  An object of the present invention is to realize an image forming apparatus that can reduce power supply voltage fluctuation without converting from an AC voltage to a DC voltage.

  According to the first aspect of the present invention, in an image forming apparatus including a component whose supplied power value is variable, a power calculation unit that calculates a power value currently supplied to the component, and the power calculation Difference value calculation means for calculating a difference value between the power value calculated by the means and a target value of the power value to be supplied to the component, and based on the difference value calculated by the difference value calculation means A control unit that sets a rate of change of the power value supplied to the component and controls the power value supplied to the component according to the set rate of change. It is a feature.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus includes a storage unit that stores a change rate table in which a change rate according to the difference value is set in advance, and the control unit includes the difference The change rate is set based on the difference value calculated by the value calculation means and the change rate table stored in the storage means.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the component includes a heating member and a pressure member that form a nip portion, and fixing the toner on the recording medium. It is a heating means for heating the heating member of the apparatus.

  According to the first aspect of the present invention, even if the AC voltage is not converted to the DC voltage, the difference between the power value currently supplied to the component and the target value of the power value to be supplied to the component is obtained. Since the power value supplied to the component can be controlled according to the change rate set based on the change rate, the power supply voltage fluctuation (flicker) can be reduced without increasing the size of the device and increasing the cost. Can do.

  According to the invention described in claim 2, since the same effect as in claim 1 can be obtained, the change rate can be set based on the difference value and the change rate table. Can be reduced.

  According to the third aspect of the present invention, the heating member of the fixing device can be heated as a component whose power value to be supplied is variable as well as the same effect as in the first or second aspect. A heating means can be used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the configuration will be described.
FIG. 1 is a schematic control configuration diagram of an image forming apparatus 1 according to the present embodiment.

  The image forming apparatus 1 according to the present embodiment receives image data from a copy function that reads an image from a document and forms the read image on a recording medium such as OHP paper or paper, or a personal computer. This is a digital multi-function peripheral having a printer function or the like that forms and outputs an image to be represented on a recording medium.

  As shown in FIG. 1, the image forming apparatus 1 includes a main body control unit 100, a storage unit 110, a DC power supply unit 200, an image reading unit 10, a printing unit 20, an operation display unit 80, a communication unit 90, and the like. Is configured to be able to electrically transmit and receive various data.

  The image reading unit 10 includes an automatic document feeder called an ADF (Auto Document Feeder) and a reading unit. The automatic document feeder allows the documents stacked on the document tray to be sequentially read from the top of the document at a reading position. It passes through the contact glass while being in close contact with it, passes through the contact glass, and is discharged to the discharge tray after the reading is completed.

  In addition, reflected light of the light irradiated on the original is imaged and photoelectrically converted by a reading unit configured with a scanner including a light source, a lens, contact glass, a CCD (Charge Coupled Device), and the like. The image is read, and the read original image (analog image signal) is output to the main body control unit 100. After A / D conversion and various image processing are performed in the main body control unit 100, the print data is sent to the print unit 20 as print data. Is output. Here, the image means not only image data such as graphics and photographs but also text data such as characters and symbols.

  The print unit 20 performs electrophotographic image formation based on input print data, and includes an image forming unit 30, a cleaning unit 40, a paper feeding unit 50, a transport unit 60, and a fixing device. 70.

  The image forming unit 30 includes a photosensitive drum, a charging device, a laser output unit that outputs laser light, and an exposure device, a developing device, and a transfer device that have a polygon mirror that scans the laser light in the main scanning direction. The photosensitive drum charged with the charging device by the image forming unit 30 is irradiated with laser light based on the print data by the exposure device to form an electrostatic latent image, and the photosensitive drum on which the electrostatic latent image is formed. An electrostatic latent image (toner image) is formed by attaching charged toner to the surface of the toner, and the toner image is transferred to a recording medium in a transfer device.

  After the toner image is transferred to the recording medium, the cleaning unit 40 removes residual charges, residual toner, and the like on the surface of the photosensitive drum.

  The paper feeding unit 50 includes a plurality of paper trays that store recording media identified in advance for each type, and a manual feed tray that can stack various types of recording media according to the needs of the user. Then, the recording medium accommodated in the paper tray or the manual feed tray is conveyed one by one from the top toward the conveyance unit by the sheet feeding roller.

  The transport unit 60 transports the recording medium transported from the paper tray or the manual feed tray to the transfer device and the fixing device 70 via a plurality of intermediate rollers and registration rollers, and sandwiches the fixed recording medium by the paper discharge roller. Output on the paper discharge tray.

  The fixing device 70 includes a heating member 71 for fixing the toner image transferred to the recording medium by heating, a pressure member 72 that presses against the heating member 71 to form a nip portion, and a heating unit 73 that heats the heating member 71. The temperature sensor 74 detects the temperature of the heating member 71, the fixing power control unit 300 that supplies power to the heating unit 73, and the like, and is driven by the main body control unit 100.

  As the heating member 71 of the present embodiment, a heating belt, a heating roller, or the like can be used, but a heating roller is preferable from the viewpoint of excellent thermal efficiency. The pressure member 72 may be a pressure roller, a pad or the like, but is preferably a pressure roller.

  As the heating means 73, the heating value changes depending on the supplied power value of a thermocouple (heater), a halogen lamp, an induction coil used to adopt an induction heating (IH) system, or the like. Can be used. Therefore, the heating means 73 is a component whose supplied power value is variable.

  The temperature sensor 74 is installed in a non-contact or in contact with the outer peripheral side of the heating member 71 corresponding to the heating unit 73, detects the temperature of the heating member 71, and outputs the detected temperature to the main body control unit 100. To do.

  The fixing power control unit 300 includes a fixing control unit 310, a voltage detection unit 321, a drive circuit unit 322, a current detection unit 323, and the like.

  The fixing control unit 310 outputs values input from the voltage detection unit 321 and the current detection unit 323 to the main body control unit 100 and drives the heating unit 73 based on an instruction from the main body control unit 100. Is calculated and output to the drive circuit unit 322.

Voltage detecting unit 321, the voltage value of the AC power input from the AC power supply unit AC to the fixing power control unit 300 (hereinafter, fixing the power supply voltage V _h) detecting the fixing control of the fixing power supply voltage V _h detected Output to the unit 310.

  The drive circuit unit 322 supplies power to the heating unit 73 based on the drive signal input from the fixing control unit 310.

The current detection unit 323 detects a current value of power supplied to the heating unit 73 (hereinafter, fixing power supply current value I _h ) based on the drive signal input from the drive circuit unit 322, and detects the detected fixing power supply current value. and it outputs the I _h the fixing control unit 310.

  The operation display unit 80 includes various operation keys such as a copy start key, a numeric keypad, and a power switch, and outputs operation signals of these keys to the main body control unit 100. The operation display unit 80 includes an LCD (Liquid Crystal Display) screen and a touch panel, and in accordance with display signal instructions input from the main body control unit 100, various operation buttons, device status displays, In addition to displaying the operation status of the function, etc., the coordinates instructed by touch are detected by the principle of coordinate reading such as electromagnetic induction type, magnetostrictive type, and pressure sensitive type, and the detected coordinates are output to the main body control unit 100 as a position signal. .

  The communication unit 90 includes a modem, a TA (Terminal Adapter), a router, and the like, and controls communication with an external device connected to the network. For example, image data can be received from an external device via the communication unit 90.

  The main body control unit 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a non-volatile RAM, and the like, and stores programs and data stored in the ROM and the non-volatile RAM such as a RAM. The data is expanded in a temporary storage area (not shown), and the entire image forming apparatus 1 is controlled based on the program, and various types of information can be transmitted to and received from each part in the image forming apparatus 1. The information received is determined, the received information is determined, information such as an operation instruction that is the determination result is output to each unit, and each unit is comprehensively controlled.

The main body control unit 100 is currently supplied to the heating unit 73 based on the fixing power supply voltage value V _h detected from the voltage detection unit 321 and the fixing power supply current value I _h detected from the current detection unit 323. A power value (hereinafter, current fixing power value W _h0 ) is calculated. Then, the main body control unit 100 calculates a difference value ΔW between the target value of the power value to be supplied to the heating unit 73 (hereinafter, the fixing target power value W _hN ) and the current fixing power value W _h0, and the calculated difference Based on the value ΔW and the change rate table stored in the storage unit 110, the change rate α of the power supplied to the heating means 73 is set, and the supply fixing power variable table is set according to the set change rate α. The power value generated and supplied to the heating means 73 is controlled. That is, the main body control unit 100 has functions as power calculation means, difference value calculation means, and control means.

When the difference value ΔW is 0, that is, when the fixing target power value W _hN and the current fixing power value W _h0 are equal, the change rate α is set to 0 in order to maintain the current fixing power value W _h0. Thus, the supply fixing power variable table is not generated.

The main body control unit 100 calculates a power value supplied to the DC load in the image forming apparatus 1 (hereinafter referred to as a DC load power supply power value W _d ) as the fixing target power value W _hN and stores it in the storage unit 110. DC power supply power value W _d from _a target value (hereinafter referred to as a target total power value W _a ) of the power value to be supplied to the entire image forming apparatus 1 determined in advance according to the operation mode of the image forming apparatus 1 being The value obtained by subtracting is calculated as the fixing target power value W _hN .

  The operation mode of the image forming apparatus 1 includes a warm-up mode in which the heating member 71 of the fixing device is raised to a temperature at which fixing can be performed, a sleep mode in which image formation is not performed for a predetermined time or more, and the image forming operation is stopped. Examples thereof include an image forming mode for forming an image on a recording medium.

The storage unit 110 stores a target total power value W _{a for} each operation mode and a change rate table in which a change rate α corresponding to the difference value ΔW is set in advance, and the generated supply fixing power variable table. Storage means for storing, and is constituted by an electrically erasable and rewritable nonvolatile storage medium constituted by a magnetic or optical storage medium or a semiconductor memory. Examples of the storage unit 110 include an HDD (Hard Disk Drive), an EEPROM (Electrically Erasable and Programmable ROM), and a flash memory. Note that the storage unit 110 may be configured to be detachably mounted.

FIG. 2 shows an example of the change rate table 111.
In the change rate table 111 shown in FIG. 2, the absolute value of the subtraction value between the fixing target power value W _hN and the current fixing power value W _h0 is set as a difference value ΔW, and the calculated difference value ΔW is in accordance with a possible range. The change rate α is set. The change rate α can be determined according to the apparatus configuration of the image forming apparatus 1 and the flicker standard.

  In FIG. 2, when the difference value ΔW is greater than 0 and less than or equal to 300, the change rate α is set as 300 [W / 10 sec], and when the difference value ΔW is greater than 300 and less than or equal to 600, the change rate α Is set as 200 [W / 10 sec], and when the difference value ΔW is larger than 600, the change rate α is set as 100 [W / 10 sec].

  That is, when the difference value ΔW is large (for example, ΔW = 600), if the supplied power is suddenly increased or caused to change, the rate of change of power per unit time increases and flicker is likely to occur. The occurrence of flicker is suppressed by reducing the electrification rate of the power and supplying power gently. When the difference value ΔW is small (for example, ΔW = 100), flicker is unlikely to occur, so the power change rate per unit time is increased and power is supplied rapidly.

Based on the current fixing power value W _h0 , the fixing target power value W _hN , and the rate of change α, the supplied fixing power variable table shows the current fixing power value W from the time (current time) when the DC load power supply value W _d is calculated. A power instruction value indicating a power value supplied to the heating unit 73 is set for each preset time (hereinafter, set time) until the time required for _h0 to become equal to or greater than the fixing target power value W _hN .

  In the present embodiment, the main body control unit 100 and the storage unit 110 have been described as separate configurations. However, the main body control unit 100 and the fixing control unit 310 may be formed as an integral configuration. However, the fixing control unit 310 may be included in the main body control unit 100, and may be realized by, for example, a system LSI (Large Scale Integration).

  The DC power supply unit 200 includes a DC power supply control unit 210, a voltage detection unit 221, a current detection unit 222, an AC / DC conversion unit 223, and the like.

  The DC power supply control unit 210 monitors the power supplied to the DC load in the image forming apparatus 1 based on an instruction from the main body control unit 100, and a value detected from the voltage detection unit 221 and the current detection unit 222. Is output to the main body control unit 100.

The voltage detection unit 221 is a voltage value of AC power input to the DC power supply unit 200 from the AC power supply unit AC, that is, a voltage value of AC power for DC load of the image forming apparatus 1 (hereinafter referred to as DC load power supply voltage value V). detects _d), the outputs detected DC load supply voltage V _d to the DC power supply control unit 210.

The current detection unit 222 is a current value of AC power input from the AC power supply unit AC to the DC power supply unit 200, that is, a current value of AC power for DC load of the image forming apparatus 1 (hereinafter referred to as DC load power supply current value I). _d ) is detected, and the detected DC load power source current value I _d is output to the DC power source controller 210.

  The AC / DC conversion unit 223 converts the AC power input from the AC power supply unit AC to the DC power supply unit 200 into DC power, and converts the converted DC power into a voltage adapted to each DC load in the image forming apparatus 1. And supply.

Next, the operation of the present embodiment will be described.
FIG. 3 shows a flowchart of the power value setting operation supplied to the heating means 73 in the present embodiment. The flowchart shown in FIG. 3 is executed at any time while the power supply is supplied to the image forming apparatus 1.

The main body control unit 100 acquires the direct-current load source voltage value V _d detected by the voltage detecting unit 221 from the DC power source control unit 210 together (step S1), the DC load supply current value I detected by the current detecting section 222 _d is acquired from the DC power supply controller 210 (step S2).

The main body control unit 100 calculates a DC load power supply power value W _d supplied to the DC load in the image forming apparatus 1 from the acquired DC load power supply voltage value V _d and the DC load power supply current value I _d (step S3). ).

Main control unit 100 reads out the target total power value W _a corresponding to the current operation mode of the image forming apparatus 1 from the storage unit 110 (step S4), and the read target total power value W _a from the DC load supply power value W _The fixing target power value W _hN is calculated by subtracting _d (step S5).

In addition, the main body control unit 100 acquires the fixing power supply voltage value V _h detected from the voltage detection unit 321 from the fixing control unit 310 and also uses the fixing power supply current value I _h detected from the current detection unit 323 as the fixing control unit. The current fixing power value W _h0 currently supplied to the heating means 73 is calculated from the acquired fixing power supply voltage value V _h and fixing power supply current value I _h (step S6).

The main body control unit 100 subtracts the calculated fixing target power value W _hN and the current fixing power value W _h0 and calculates the absolute value of the subtraction value as the difference value ΔW (step S7).

The main body control unit 100, if the difference value ΔW is 0 in step S7, the process returns to step S1 for keeping the current fixing power value W _h0 without changing the current fixing power value W _h0, the difference value ΔW If it is not 0, the change rate α is calculated with reference to the calculated difference value ΔW and the change rate table stored in the storage unit 110 (step S8).

The main body control unit 100 generates a supply fixing power variable table based on the current fixing power value W _h0 , the fixing target power value W _hN , and the change rate α (step S9).

FIG. 4 shows an example of the supply fixing power variable table.
The supply fixing power variable table 112 shown in FIG. 4 changes according to the change rate table 111 shown in FIG. 2 when the current fixing power value W _h0 is 500 [W] and the fixing target power value W _hN is 1000 [W]. It is an example of a supply fixing power variable table generated when the rate α is calculated as 200 [W / 10 sec].

As shown in FIG. 4, the supplied fixing power variable table 112 uses the current time as a reference (0 [sec]), and the power supplied to the heating unit 73 every elapse of a set time (here, 5 [sec]). Since the instruction value is set, the change rate α is 200 [W / 10 sec], and the current fixing power value W _h0 is smaller than the fixing target power value W _hN , the power instruction value is the fixing target power value. The power instruction value is set to increase by 100 [W] every time the set time elapses until a time (in this case, 25 [sec]) that becomes W _hN or more.

  The main body control unit 100 refers to the supply fixing power variable table, sets the power instruction value set after the set time has elapsed from the current time (step S10), and determines whether or not the set time has passed ( When it is determined that the set time has not elapsed (step S11) (step S11; No), the process waits until the set time elapses.

When determining that the set time has elapsed (step S11; Yes), the main body control unit 100 outputs the set power instruction value to the fixing control unit 310, and the fixing control unit 310 outputs the power value corresponding to the power value instruction value. Calculates the drive signal supplied to the heating means 73 and outputs it to the drive circuit section 322. Further, the main body control unit 100 determines whether or not the target total power value W _a and the DC load power source power value W _d calculated when the fixing target power value W _hN is calculated are not changed (Step S12). .

In step S12, when determining whether or not the target total power value W _a and the DC load power source power value W _d are not changed, the main body control unit 100 performs the same operation as in steps S1 to S4 to perform the target total power value. The power value W _a and the DC load power source power value W _d are calculated, and the calculated target total power value W _a and the DC load power source power value W _d and the fixing target power value W _hN are calculated. It is determined whether there is any change by comparing the total power value W _a and the DC load power source power value W _d , respectively.

The operation of the main body control unit 100 returns to step S1 when it is determined that there is a change in at least one of the target total power value W _a and the DC load power source power value W _d (step S12; No).

When determining that both the target total power value W _a and the DC load power supply power value W _{d have not been} changed (step S12; Yes), the main body control unit 100 refers to the supply fixing power variable table and is set after the set time has elapsed. It is determined whether or not there is a power instruction value (next power instruction value) (step S13).

  When it is determined that the next power instruction value is present (step S13; No), the main body control unit 100 returns to step S10 and sets the next power instruction value.

  When determining that there is no next power instruction value (step S13; Yes), the main body control unit 100 ends this process.

In FIG. 5, the example of the graph which shows the time change of the electric power value supplied to the heating means 73 is shown.
In FIG. 5, the power value P supplied to the heating unit 73 according to the supply fixing power variable table 112 shown in FIG. 4 generated by executing the process shown in FIG. The approximate curve Pa of the power value P supplied to is indicated by a one-dot chain line.

As shown in FIG. 5, the power value supplied to the heating unit 73 reaches every fixing time (every 5 sec) until the fixing target power value W _hN (here, 1000 [W]) is reached. The power value supplied to the heating means 73 is increased stepwise, and the approximate curve Pa becomes a temporary curve with the calculated change rate (here, 200 [W / 10 sec]) as an inclination.

  Note that the change rate table in the present embodiment has been described with reference to a change rate table in which the change rate α in which the approximate curve becomes a primary curve is defined, but the change in which the approximate curve becomes a quadratic curve such as a hyperbola or a parabola. It may be a change rate table in which the rate α is determined.

Thus, according to the present embodiment, the power value currently supplied to the heating unit 73 (current fixing power value W _h0 ) and the heating unit 73 are supplied without conversion from an AC voltage to a DC voltage. Since the power value supplied to the heating means 73 can be controlled according to the change rate α set based on the difference value ΔW between the power value and the target value (fixing target power value W _hN ), fixing Power supply voltage fluctuation (flicker) can be reduced without increasing the size and cost of the apparatus and the image forming apparatus.
Further, since the change rate α can be set based on the difference value ΔW and the change rate table, the control load of the main body control unit 100 can be reduced.

  Further, the present invention is not limited to the contents of the above embodiment, and can be appropriately changed without departing from the gist of the present invention.

2 is a schematic control configuration diagram of an image forming apparatus 1 according to the present embodiment. FIG. It is an example of the change rate table 111. It is a flowchart of the electric power value setting operation | movement supplied to the heating means 73 in this Embodiment. It is an example of the supply fixing power variable table 112. It is an example of the graph which shows the time change of the electric power value supplied to the heating means 73.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image reading part 20 Print part 30 Image forming part 40 Cleaning part 50 Paper feeding part 60 Conveying part 70 Fixing apparatus 71 Heating member 72 Pressing member 73 Heating means 74 Temperature sensor 100 Main body control part 110 Storage part 111 Change Rate table 112 Supply fixing power variable table 200 DC power supply unit 210 DC power supply control unit 221 Voltage detection unit 222 Current detection unit 223 AC / DC conversion unit 300 Fixing power control unit 310 Fixing control unit 321 Voltage detection unit 322 Drive circuit unit 323 Current Detection unit AC AC power supply unit I _d DC load power supply current value I _h Fixing power supply current value V _d DC load power supply voltage value V _h Fixing power supply voltage value W _a Target total power value W _d DC load power supply power value W _h0 Current fixing power Value W _hN fixing target power value ΔW Difference value α Change rate

Claims (3)

In an image forming apparatus provided with a component whose power value to be supplied is variable,
Power calculating means for calculating a power value currently supplied to the component;
Difference value calculating means for calculating a difference value between the power value calculated by the power calculating means and a target value of the power value to be supplied to the component;
Based on the difference value calculated by the difference value calculation means, a change rate of the power value supplied to the component is set, and the power value supplied to the component is set according to the set change rate. Control means for controlling;
Providing
An image forming apparatus. Storage means for storing a change rate table in which a change rate according to the difference value is preset;
The control means includes
Setting the rate of change based on the difference value calculated by the difference value calculating unit and the rate of change table stored in the storage unit;
The image forming apparatus according to claim 1. The component is:
Heating means for heating the heating member of the fixing device having a heating member and a pressure member for forming the nip portion and fixing the toner on the recording medium;
The image forming apparatus according to claim 1, wherein:

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