JP2005257831A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict power consumption to a set upper limit or lower, and to finely optimize the electric power of fixing. <P>SOLUTION: The image forming apparatus includes an image forming means for forming a visible image on a photoreceptor; a means for transferring the visible image to paper; a fixing means 120 for heating the paper having the visible image transferred to it; and a PC 3. The image forming apparatus is provided with power supply control means TH and DSP, which control a power supply duty for a fixing heater so that the power is not higher than the upper limit value of power supplied to the fixing means which decreases or increases, in a way so as to be opposite of the increase or decrease of load power except power supplied to the fixing heater. The power supply duty for adjusting the fixing temperature, detected by a temperature sensor to a target temperature, is restricted to be not higher than the upper limit value of the power supplied to the fixing means. The upper limit value corresponds with an image forming mode having a mode index by which determination is made whether monochrome image are formed or a full-color image is formed and a mode index by which determination is made whether a finisher is used. The upper limit value also corresponds with an operating process having standby, image formation, and paper ejection as status indexes, and power is supplied to the fixing heater, suppressing the duty. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including an image forming unit that forms a visible image on a photoreceptor, a unit that transfers the visible image to a sheet, and a fixing unit that heats the sheet to which the visible image is transferred. The present invention relates to an image forming apparatus having different power consumption.

  Even in the image forming apparatus, the power consumption of the copying machine is large. Particularly, a multifunction machine based on a digital copying machine and added with various image processing functions and document processing functions consumes a large amount of power. In general offices in Japan, the maximum power that can be normally used is 1500V at 100V15A. More power supplies (100V15A or more or 200V) require special power supply work. The current copying machine has an improved printing speed and a corresponding increase in power consumption. In general, in an image forming apparatus using toner, three elements of heat, pressure, and time are important for fixing the toner on the printing paper. The larger the heat and pressure, the better the toner is fixed. However, the greater the amount of heat, the more the power consumption increases and the in-machine temperature increases. If the pressure is too high, the printing paper may be wrinkled or a paper jam may occur. The time for applying heat and pressure in the fixing unit is determined by the paper conveyance speed (printing speed). If the printing speed is increased, it becomes difficult to transfer the heat of fixing to the printing paper, so that the fixing property is deteriorated. Therefore, it is necessary to increase the amount of heat for fixing as the printing speed increases. However, a machine with a fast printing speed increases the load for feeding and transporting printing paper quickly and other loads, so it is difficult to increase the amount of heat for fixing.

Japanese Patent Laid-Open No. 5-233636 JP-A-6-4003 JP-A-6-95541.

  Patent Document 1 describes a fixing device that prevents a fixing failure due to a shortage of heat even when the copying speed at the time of black-and-white copying is high, and also prevents a fixing failure due to a decrease in the temperature of a heating roller at the start of copying. The heating roller is equipped with two heaters with different power capacities. If copying is in progress, the heaters are switched between color copying and black-and-white copying, so the power capacity is small during color copying, which consumes a large amount of power for the halogen lamp. Turn on the heater. Further, a heater having a large power capacity is turned on during black-and-white copying that does not consume a large amount of power in the halogen lamp.

  In Patent Document 2, heaters are provided for each of the three fixing rollers, and the total power consumption does not exceed the set power in the lighting priority order of each heater set separately according to the full color copy mode and the black and white copy mode. Thus, there is described an electrophotographic apparatus that turns off heaters having a low priority according to the copy mode.

  In Patent Document 3, a plurality of heat rollers having heater lamps are provided, and by these heat rollers, fixing portions for black-and-white copying and full-color copying are formed, so that the power consumption of the electrophotographic apparatus is within the maximum rated power. Describes a fixing device for turning on a heater lamp. Priorities are assigned to the heater lamps in advance, and the temperature control device sequentially performs temperature control for switching on / off energization of the heater lamps according to the priorities.

  As described above, it is a common practice to vary the power consumption by providing a plurality of heaters and changing the number of heaters to be lit depending on the print mode. However, if the power consumption is varied by changing the number of heaters, fine power setting (variable) cannot be performed. Although the system has sufficient power consumption and can be supplied for fixing, it cannot be optimized and the amount of heat is small, fixing failure occurs, or the maximum power consumption of 1500 W is exceeded and the breaker in the power supply path operates. There is a possibility that it will cause trouble.

  An object of the present invention is to suppress power consumption below a set upper limit and to finely optimize fixing power.

  For example, when power is supplied to a 1000 W heater, the power consumption can be suppressed to 700 W by setting the power supply duty to 70%. In an image forming apparatus capable of printing in both black and white (single-color image formation) and color (full-color image formation), in addition to black-and-white printing, color printing that performs printing processing for a total of four colors of cyan, magenta, and yellow In general, the load (power consumption) is larger. Assuming a load of 700 W for monochrome printing and 800 W, which is 100 W for color, and assuming that the maximum power consumption is 1500 W, it is possible to supply 800 W for monochrome printing and 700 W for color printing. By controlling the power supply duty to the fixing device, it is possible to supply 800 W for fixing during monochrome printing and 700 W for fixing during color printing, and optimize the total power consumption of the system so that it does not exceed the maximum allowable power of 1500 W. is there.

  In the operation process from the start of image formation to the completion of paper discharge, the image forming apparatus is controlled (ON) and stopped (OFF) at a predetermined timing. That is, the power load increases or decreases. Further, by connecting an optional device, the image forming apparatus can be used for various document processing, but the power load increases. In addition, the power consumption of the printer body alone is different, for example, the printer unit B has a higher power load than the printer unit A.

  The magnitude of the power load is determined by the type of the connected device, but the magnitude of the power load varies depending on the operating state of each device. For example, B has a smaller standby power load than finisher A, but the load is larger and the load is larger in B when discharging in normal operation than in standby. Some finishers also have punch and stapling functions. During the punching operation, the punch unit operates every time the paper is passed, so the load frequently increases. During the stapling operation, the stapling is performed after the printing is completed. Therefore, during printing, the load is not changed from that during the normal paper discharging operation, and a large load is generated after the printing is completed. The load varies depending on the type of load and the operation timing. Although the load varies depending on the selection of the connected load and operation (imaging mode and operation process), the power that can be supplied to the fixing also varies depending on the varying load. In the present invention, the power supplied to the fixing is varied by controlling the power supply duty in accordance with the fluctuating load. An image forming apparatus according to the present invention which performs this is as follows.

(1) In an image forming apparatus comprising an image forming means for forming a visible image on a photoreceptor, a means for transferring the visible image to a paper, and a fixing means (120, PC3) for heating the paper to which the visible image is transferred.
In the image forming apparatus, a power supply duty for supplying power to the fixing unit is less than or equal to an upper limit value of fixing unit input power that decreases or increases in response to an increase or decrease in load power excluding power input to the fixing unit. An image forming apparatus comprising power supply control means (TH, DSP) for controlling.

  In addition, in order to make an understanding easy, the symbol or the corresponding matter of the corresponding element of the Example which is shown in drawing and mentioned later in parentheses was added as an example for reference. The same applies to the following.

  The power supply control means (TH, DSP) is less than or equal to the fixing means input power upper limit value that decreases or increases in response to an increase or decrease in load power excluding the power input to the fixing means (120, PC3). Therefore, the fixing power can be finely controlled with a high degree of freedom. It is possible to obtain an optimum fixing power within an allowable range.

  (2) The power supply control means (TH, DSP) includes an image forming mode in which whether the image forming apparatus uses single color image formation or full color image formation and whether or not a finisher is used, a standby mode, an image formation mode, The power supply duty for supplying power to the fixing unit is controlled to be equal to or less than the fixing unit input power upper limit value addressed to the image forming mode and the operation process in correspondence with the operation process using the paper discharge as a state classification index. The image forming apparatus according to (1). According to this, the maximum power can be input to the fixing means (120, PC3) within the usable power range corresponding to the image forming mode and the operation process.

  (3) The power supply control means (TH, DSP) determines an upper limit value of power input to the fixing means assigned to the image forming mode and the operation process based on standby power and maximum power consumption of the power consuming device of the image forming apparatus. The image forming apparatus according to (2), wherein the calculated image is stored in a memory (66c). According to this, the power upper limit value addressed to the image forming mode and the operation process is read from the memory without performing the calculation unless the power consuming device of the image forming apparatus is changed after the data is written in the memory. The power supply duty can be converted into an upper limit value. Calculation of the power supply duty upper limit is easy.

  (4) The fixing means (120, PC3) includes a temperature sensor (TH), and the power supply control means (TH, DSP) is a power supply duty for adjusting a temperature detected by the temperature sensor (TH) to a target temperature. The power supply duty upper limit value for the current image forming mode and operation process stored in the memory is converted into a power supply duty, and the calculated power supply duty and the low value of the converted power supply duty are supplied. The image forming apparatus according to (3), wherein power is supplied to the fixing unit with a duty (FIG. 10). According to this, electric power necessary for setting the temperature detected by the temperature sensor (TH) as the target temperature within the range of the input power upper limit corresponding to the image forming mode and the operation stroke is supplied to the fixing means. High reliability with the fixing temperature as the target temperature.

  (5) The power supply control means (TH, DSP) determines the upper limit value of the fixing means input power addressed to the image forming mode and the operation process based on the standby power and the maximum power consumption of the power consuming device of the image forming apparatus. The image forming apparatus according to (2), wherein the image forming apparatus calculates, and converts the calculated fixing unit input power upper limit value into a power supply duty corresponding to the upper limit value and stores the converted power supply duty in a memory (66ca). According to this, the power supply duty upper limit value addressed to the image forming mode and the operation process is read from the memory without performing the above calculation unless the power consuming device of the image forming apparatus is changed after the data is written in the memory. be able to. Use of the power supply duty upper limit is easy.

  (6) The fixing means (120, PC3) includes a temperature sensor (TH), and the power supply control means (TH, DSP) is a power supply duty for adjusting a temperature detected by the temperature sensor (TH) to a target temperature. The power is supplied to the fixing unit at a power supply duty addressed to the current image forming mode and the operation stroke, which is stored in the memory, and a low value power supply duty among the calculated power supply duties (FIG. 11). The image forming apparatus according to (5) above. According to this, electric power necessary for setting the temperature detected by the temperature sensor (TH) as the target temperature within the range of the input power upper limit corresponding to the image forming mode and the operation stroke is supplied to the fixing means. High reliability with the fixing temperature as the target temperature.

  FIG. 1 shows the external appearance of a multifunction copying machine that is a first embodiment of the present invention. This multi-function copier is roughly an automatic document feeder [ADF] 30, an operation unit 20, a color scanner 10, a color printer 100, a relay unit 32, a stapler and a large amount of imaged paper. The stacker includes a finisher 34 with a shift tray, a duplex reversing unit 33, a paper feed bank 35, a large-capacity paper feed tray 36, and a 1-bin paper discharge tray 31.

  FIG. 2 shows the configuration of the color printer 100. Reference numeral 101 denotes a flexible photosensitive belt serving as a belt-shaped image carrier. The photosensitive belt 101 is installed between the rotating rollers 102 and 3, and is rotated in the direction indicated by the arrow A (clockwise) in FIG. ). In the figure, reference numeral 104 denotes a charging charger that uniformly charges the surface of the photosensitive belt 101, and reference numeral 105 denotes a laser exposure apparatus that is an image writing unit. In the figure, 106 is a color developing device, 106a is magenta, 106b is cyan, 106c is yellow, and 106d is a black developing unit.

  Further, reference numeral 109 in the figure denotes an intermediate transfer belt as an image carrier and an intermediate transfer medium. The intermediate transfer belt 109 is installed on a rotating roller 110-112, and is driven in the direction indicated by an arrow B in FIG. (Counterclockwise) The photosensitive belt 101 and the intermediate transfer belt 109 are in contact with each other by a symbolless rotating roller portion of the photosensitive belt 101. On the intermediate transfer belt 109 side of the contact portion, a conductive bias roller 113 is in contact with the back surface of the intermediate transfer belt 110 under predetermined conditions.

  The photosensitive belt 101 is uniformly charged by a charging charger 104 and then exposed by scanning with a laser beam modulated by an image recording signal by a laser exposure device 105. As a result, an electrostatic latent image is formed on the photosensitive belt 101. Here, the image recording signal for modulating the laser beam is for each color (single color) obtained by decomposing a desired full color image into magenta, cyan, yellow, and black (Bk) color information. The formation of the electrostatic latent image and the development by the color in the developing devices 106a to 106d are repeated for the number of colors (for example, magenta, cyan, yellow, and black, a total of four times). The developed images (toner images) appearing by development are transferred onto the intermediate transfer belt 9 in a superimposed manner.

  That is, each single-color image (toner image) formed on the photosensitive belt 1 rotating in the direction of arrow A in the figure is synchronized with the photosensitive belt 101 on the intermediate transfer belt 109 rotating in the direction of arrow B in the figure. , Magenta, cyan, yellow, and black are sequentially superimposed and transferred by a predetermined transfer bias applied to the bias roller 113. The magenta, cyan, yellow, and black images superimposed on the intermediate transfer belt 109 are fed from the paper feed cassette 116a of the paper feed tray 116 to the paper feed roller 117, the transport roller pair 118a and 118b, and the registration roller pair 119a and 119b. After that, the images are collectively transferred onto the transfer paper conveyed to the transfer roller 114. After the transfer is completed, the toner image on the transfer paper is fixed (heat-pressed) on the transfer paper by the fixing device 120. As a result, a full-color image is completed, and the transfer paper is discharged to the paper discharge stack section 122 through the paper discharge roller pair 121a and 121b.

  In the figure, reference numeral 107 denotes a cleaning blade that always contacts the photosensitive belt 101 and wipes off the toner on the photosensitive belt 101. Reference numeral 115 denotes a cleaning device for the intermediate transfer belt 109, and the cleaning brush for the cleaning device 115. 115a is held at a position separated from the surface of the intermediate transfer belt 110 during the image forming operation, and a formed image is transferred onto the transfer paper described above and then brought into contact with the surface of the intermediate transfer belt 110.

  Further, the photosensitive belt 101, the charging charger 104, the intermediate transfer belt 109, and the cleaning devices 107 and 115 are integrally assembled into a process cartridge to form a unit.

  Reference numeral 108 denotes a toner adhesion amount sensor for detecting the toner adhesion amount on the photosensitive belt 101. The toner adhesion amount sensor 108 used this time generates and outputs a voltage Vs, that is, a detection signal corresponding to the amount of light received by the photodiode, in which the light emitting portion is an infrared light emitting diode and the diffuse reflected light receiving portion is a photodiode. That is, a toner density sensor that measures the amount of diffusely reflected light.

  Inside the fixing roller of the fixing device 120, there is a fixing heater (halogen lamp) 123C. The heater driver PC3 (FIG. 4) is energized to the fixing heater 123C, whereby the fixing heater 123C generates heat and generates infrared rays. Then, the fixing roller is heated.

  FIG. 3 shows an outline of the electric system of the copying machine shown in FIG. One MPU 51 on the main control plate 50 and one CPU 12 on the scanner control plate 11 are used as a copier mechanical control unit, that is, a main part of image reading and image forming process control. The MPU 51 performs image-related sequence and fixing control and system-related control, and the CPU 12 performs scanner-related control. The MPU 51 and the CPU 12 are connected by an image data interface and a serial interface.

  In FIG. 3, 20 is an operation unit, 70 is an I / O control board equipped with an input / output electric circuit, 92 is an LD control board for controlling laser light for image exposure, 41 is a paper feed control board, 13 is A reading control board on which a CCD is mounted, 80 is a power supply device, and 90 is a mother board.

  A printer controller (board) 60 controls a printer function for printing a document of a host such as a personal computer or a word processor, and a combined operation mode of a copy, facsimile, and printer. Reference numeral 91 denotes an application expansion unit for realizing a composite function, which is a facsimile control unit equipped with a FAX function. Reference numeral 80 denotes a power supply / AC control board.

  FIG. 4 shows an outline of a power supply circuit on the power supply device 80 and an outline of an electric load fed by the power supply circuit. The power supply device 80 includes a circuit breaker CB, an arrester AR, and a filter 81 for removing AC AC noise, an AC current detection circuit ISEN0 for detecting an AC AC input current instantaneous value, and a main power switch SWap (AC input switch). The rectifying / smoothing circuit 82 that rectifies and smoothes the AC voltage supplied by closing (ON) the first and second power supply circuits (DC / DC converters) that are supplied with the output DC and generate DC voltages 5V and 24V, respectively. There are PC1, PC2, a zero cross detector 85n that generates a pulse (zero cross pulse) at the zero cross point of the AC voltage, and a heater driver PC3 that is fed by closing (turning on) the power relay RA2. In the heater driver PC3, there is a triac TR (FIG. 5) for applying an AC voltage to the fixing heater (halogen lamp) 123C and a gate circuit GT (FIG. 5) for energizing the triac.

  The digital controller 85 controls the conduction of the switching FETs 1 and 2 (FIG. 5) of the first and second power supply circuits PC1 and PC2 and the TRIAC TR of the heater driver PC3 by applying PWM pulses PWM1 to PWM3 to them. . In this embodiment, a digital signal processor DSP is used for the digital controller 85. Hereinafter, it is expressed as a DSP.

  When the main power switch SWap is switched from open (OFF) to closed (ON) and the AC power supply AC is applied and a DC voltage appears in the rectifying / smoothing circuit 82, the switch circuit (SW) 83 is thereby turned on and the battery 84 is turned on. Is applied to the DSP 85. When the DSP 85 energizes the relay driver, the control relay RA3 is turned on to supply power to the power relay RA2, and the power relay RA2 is turned on to supply an AC voltage to the heater driver PC3.

  First and second power supply circuits PC1 and PC2 of 5V and 24V are connected to loads such as a scanner motor and an ADF (automatic document feeder), and supply necessary voltages to the loads. The heater driver PC3 outputs AC 100V to the fixing heater 123C.

  The DSP 85 communicates with the printer controller 60 mounted on the mother board 90 by UART (Universal Asynchronous Receiver Transmitter: serial communication). Although not shown, the printer controller 60 is a computer system including a CPU, a nonvolatile memory, a ROM, a RAM, and an image memory.

  FIG. 5 shows the configuration of the switch circuit 83 shown in FIG. 4, the first power supply circuit PC1 for generating 5V, and the heater driver PC3. A 100 V commercial AC voltage is applied to the rectifying and smoothing circuit 82 through the noise filter 81 when the main power switch SWap is turned on.

  The noise filter 81 is an input filter that blocks high-frequency noise of the 100V commercial AC line from entering the switching power supply, that is, the power supply circuits PC1 to PC3, and prevents high-frequency noise generated by the switching power supply from leaking to the commercial AC line. It is. The AC voltage is applied to the rectifying / smoothing circuit 82 including the full-wave rectifying diode bridge and the smoothing capacitor and the heater driver PC3 through the input filter 81.

  The output voltage of the rectifying / smoothing circuit 82 is also applied to a starting circuit composed of a resistor and a relay RA1. When the output voltage of the rectifying / smoothing circuit 82 is applied, the relay contact of the relay RA1 between the diode D4 of the switch circuit (SW) 83 and the operating voltage input terminal Vcc of the DSP 85 is closed by the relay contact RA1. Since the diode D4 is connected to the battery 84, the battery voltage is applied to the DSP 85, whereby the DSP 85 is activated and outputs the first PWM pulse PWM1 to the switching driver DRIVE1 of the first power supply circuit PC1 that generates 5V.

  As a result, the first power supply circuit PC1 that generates 5V enters an operating state and generates a 5V DC voltage. The output DC voltage of the rectifying / smoothing circuit 82 is applied to the primary winding of the transformer TR1 in the first power supply circuit PC1. When the switching element FET1 is turned on, a current flows from the rectifying / smoothing circuit 82 to the primary side ground via the primary winding, the switching element FET1 and the current value detection circuit ISEN1.

  The switching driver DRIV1 is connected to a PWM output port that outputs a first PWM pulse PWM1 that is a switching ON / OFF signal of the DSP 85. The primary side switching circuit is constituted by DRIV1, transformer TR1 and switching element FET1, and the output voltage of rectifying and smoothing circuit 82 is chopped by switching in response to the PWM pulse, and the primary winding of transformer TR1 is pulse-energized.

  On the secondary side of the transformer TR1, there is an output circuit that converts a pulse voltage induced in the secondary winding into a direct current and outputs it. The output circuit includes diodes D1 and D2, a choke coil CH1, an output voltage detection circuit VSEN1, and a smoothing capacitor.

  The same is true for the configuration and operation of the second power supply circuit PC2 that generates 24V, and the control operation of the DSP 85 for them (giving PWM2). However, in the second power supply circuit PC2 that generates 24V, in which the power capacity of the generation circuit is large, a plurality of switching element FETs are used in parallel connection.

  The heater driver PC3 that energizes the fixing heater 123C includes a triac TR that can turn on / off the positive half wave and the negative half wave of the AC voltage, and a gate circuit GT that energizes the triac TR. The gate circuit GT While the power supply duty signal PWM3 provided by the DSP 85 is at the high level H, the triac TR is turned on at intervals of AC half-waves. When the power supply duty signal PWM3 is changed from H to a low level L, the triac TR is turned off at the end point (zero cross point) of the AC half wave immediately after that. The fixing device 120 has a thermistor TH for detecting the fixing temperature, and a temperature signal as an output thereof is given to the DSP.

  The CPU and MPU that monitor inputs even in the energy saving standby mode and the circuit that generates an external input signal in the energy saving standby mode of the printer controller 60, the I / O control board 70, and the main control board 50 include a first power supply circuit PC1. Supply power.

  FIG. 6 shows the configuration of the DSP 85. In this example, an event manager is used for the PWM pulse generator 85e. This includes a plurality of PWM pulse output ports, and the CPU 85a loads the data defining the PWM pulse and the pulse duty addressed to each output port into a pulse generation control register in the PWM pulse generator 85e. When this load is present, the PWM pulse generator 85e generates a PWM pulse defined by the register data and outputs it from the PWM pulse output port. In this embodiment, the PWM pulses PWM1 and PWM2 are output from the two PWM pulse output ports PWM1 and PWM2 to the switching drivers DRIVE1 and DRIVE2 of the first power supply circuit PC1 and the second power supply circuit PC2. The data defining the period and duty (energization duty) of each PWM pulse is set by the CPU 85a in the pulse generator 85e.

  The zero cross pulse generated by the zero cross detector 85n (FIG. 4) is applied to another PWM pulse generator 85o. For this purpose, the CPU 85a loads the power supply duty data (PWM3d: FIG. 10 / Spwm: FIG. 11) that defines the PWM pulse period and pulse duty addressed to each output port. When this load is present, the PWM pulse generator 85o generates the PWM pulse 3 defined by the power supply duty data (PWM3d / Spwm) and outputs it to the gate circuit GT (FIG. 5). In this embodiment, as shown in FIG. 12, the period of the PWM pulse 3 is 5 periods of the input AC voltage, and the power supply duty data (PWM3d / Spwm) is any number in 5 periods (10 half waves) ( a) half-waves are conducted and applied to the halogen lamp of the fixing heater 123c. The PWM pulse generator 85o sets the output (PWM3) to H and then counts the zero cross pulse. When the count value reaches a, the PWM 3 is switched to L to count the zero cross pulse and the count value reaches 10−a. After setting PWM3 to H, the zero cross pulse is counted, and the count and output level are switched. The gate circuit GT converts the PWM3 H output from the PWM pulse generator 85o into a conduction energizing level and adds it to the gate of the triac TR. At the PWM3 L, the gate circuit GT gives a non-conduction level to the gate of the triac TR. The triac TR conducts from the zero crossing point immediately after PWM3 becomes H, and becomes non-conducting from the zero crossing point immediately after PWM3 becomes L. As a result, the AC voltage indicated by the solid line waveform in FIG. 12 is applied to the halogen lamp of the fixing heater 123c. When the duty is 10% (a = 1), only one half of the continuous 10 half waves of the AC voltage is applied to the halogen lamp of the fixing heater 123c when the triac TR is turned on (conductive). Since the rated power consumption of the halogen lamp of the fixing heater 123c is 1000 W, the power consumption of the fixing heater 123c at a duty of 10% is 100 W. When the duty is 20% (a = 2) to 100% (a = 10), the power consumption of the fixing heater 123c is 200W to 1000W.

  The input channel No. of the A / D converter 85i in the DSP 85 is set. From 0 to 8, the output voltage V1 and output current I1 of the first power supply circuit PC1, the output voltage V2 and output current I2 of the second power supply circuit PC2, the AC input instantaneous current I0, the AC input instantaneous voltage V0, and the fixing temperature HM Each voltage (analog signal), that is, a detection signal is applied.

  The A / D converter 85i converts the detection signal (feedback signal) applied to the designated input channel into digital data under the control (instruction) of the CPU 85a via the interface 85h and outputs its own output. Latch in register and generate conversion complete signal.

  In response to the conversion completion signal, the CPU 85a reads digital data (A / D conversion data), that is, detection data (feedback data), and sets the output voltages of the first and second power supply circuits PC1 and PC2 to the set voltage (5V, 24V) PWM 1 and 2 pulse duty calculation, writing of data defining it to the pulse generator 85e, and PWM 3 pulse duty calculation for setting the temperature detected by the thermistor TH to the fixing target temperature And writing the data defining the same into the pulse generator 85o, checking the output voltage abnormality and output current abnormality of the first and second power supply circuits PC1 and PC2, and the PWM pulse output when there is an abnormality ( PWM1 and PWM2) are stopped.

  A program for performing the above-described operation or processing of the CPU 85a is written in the EEPROM 7b. The RAM 85c is used for temporary storage or storage of data.

  FIG. 7 shows the start-up operation of the power supply device 80 when the main power switch SWap is switched from open (off) to closed (on). When the main power switch SWap is turned on (step 1), a current flows through the relay RA1 of the starting circuit, and the contact piece RA1 is turned on (step 2). In the following description, the word “step” is omitted in parentheses, and step no. Write numbers only. When the relay contact RA1 is turned on, a voltage is supplied from the battery 84 to the power supply terminal Vcc of the DSP 85 via the diode D4, and the DSP 85 is activated (3). When the DSP 85 is activated, the DSP 85 activates the first power supply circuit PC1 that is a DC / DC converter that generates a 5V DC voltage. That is, the PWM control for adjusting the duty of the first PWM pulse so that it becomes the target value 5V with reference to the output of the first PWM pulse PWM1 and its output voltage ("5V in FIG. 8"). "Voltage control" (72) and "5V current abnormality control" (74)) are started (4). When the first power supply circuit PC1 is activated, the 5V direct current is supplied to the printer controller 60 of the motherboard 90 and the MPU 51 (FIG. 3) of the main control board 50 and to the circuit unit required for state monitoring and control by them, and engine control means (CPU and MPU 51 of controller 60) are activated (5). When the controller 60 completes the start-up, the DSP 85 instructs the DSP 85 to turn on the power relay RA2 (energization of the relay coil of the control relay RA3), and the DSP 85 activates the relay driver accordingly, thereby turning on the control relay RA3. As a result, the power relay RA2 is turned on (6).

  Next, the controller 60 instructs the DSP 85 to perform fixing heat-up, and in response to this, the DSP 85 starts to output the PWM 3 that energizes the heater driver PC5 for the fixing heater (turns on the triac TR) (7). This is started at an earlier timing than the second power supply circuit PC2 that supplies power to the power system because the heat capacity of the fixing roller incorporating the fixing heater 123C is large and it takes time to rise in temperature. When the temperature of the fixing heater 123C reaches a predetermined value (reload temperature: 170 ° C.), the start-up process is terminated, and the temperature control is switched to the fixing target temperature (180 ° C.). When this switching is finished, the second power supply circuit PC2 which is a DC / DC converter is started (8). When the output voltages of the power supply circuits PC1 and PC2 exceed a predetermined value, the DSP 85 notifies the power supply ready to the CPU of the controller 60 by UART communication, and the CPU of the controller 60 performs homing via the MPU 51 in response thereto. (9). In this homing, the CPU of the printer controller 60 instructs each part of the copying machine to execute a homing operation for adjusting a homing position such as a scanner position and a FIN (finisher) tray position.

  When the homing operation is completed, the CPU of the printer controller 60 thereafter performs normal processing of the copying machine. As is well known in this normal processing, the CPU of the printer controller 60 sets the power saving mode when there is no copy or print instruction and there is no operation on the operation unit 20 and the set time has elapsed. In this embodiment, the DSP 85 is instructed to stop the voltage output of the second and heater drivers PC2 and PC3. In response to this, the DSP 85 stops the voltage output of the second and heater drivers PC2, PC3.

  That is, the copying machine of this embodiment has a “pause mode” that is a power saving mode. In this mode, when the copying machine is not used for a long time, only the 5V voltage of the first power supply circuit PC1 that generates 5V is left, and the output of other DC voltages is turned off to realize a low power consumption state. The “pause mode” is automatically shifted when the operation of the copying machine is not performed for a preset time. Alternatively, when the power subkey on the operation unit 20 is pressed for a few seconds, the process proceeds. To cancel the power saving mode, press the power subkey for a few seconds.

  FIG. 8 shows an outline of power output control of the CPU 85a of the DSP 85. When the voltage of the battery 84 is applied to the DSP 85 by closing the relay contact RA1, an operating voltage is applied to the CPU 85a (61). This activates the CPU 85a, initializes its input / output ports, internal timers and registers, sets them to the assigned state during standby, and sets other elements of the DSP 85 to the initial state (62).

  Next, the CPU 85a starts a timer of Ts time limit for determining the reading cycle (sampling cycle) Ts of the AC instantaneous voltage V0 using the A / D converter 85i (63), and executes it in response to the time over. The timer interrupt to be performed is permitted (64). When the timer interrupt is permitted, the CPU 85a starts oscillation of the PWM pulse PWM1 with the reference value duty assigned to the PWM1, and outputs it to the FET driver DRIV1 of the first power supply circuit PC1 (65). Then, the communication interruption in response to the transmission from the printer controller 60 is permitted (66a).

  The above is the initial operation of the DSP 85 corresponding to the startup operations 1 to 4 shown in FIG. 7A of the power supply device 80, whereby the first power supply circuit PC 1 generates a voltage and the main control The CPU or MPU of the board 50 and the printer controller 60 is activated ((a) in FIG. 7). As a result, the CPU of the printer controller 60 gives a command to the CPU 85a of the DSP 85 by communication, and starts steps 6 to 9 in FIG. Here, the DSP 85 obtains an executable image forming mode corresponding to the system configuration of the copying machine (FIG. 1) and a power consumption group (components and their power consumption) from the printer controller 60, and saves them in the RAM (66b). Next, for each image forming mode, the power consumption of the entire copier, excluding the power consumption of the fixing heater, and the power consumption of the entire copier, excluding the power consumption of the fixing heater, is divided into standby, image forming, and paper discharge operation strokes. Calculate (66c).

  In this embodiment, the image forming mode is a single color image or full color image, whether or not the finisher is used, and whether or not the finisher puncher is used. It is divided into. Whether or not the finisher stapler is used can also be used as an index for distinguishing the image forming mode. However, the puncher is driven when one sheet of imaged paper is ejected. Since it is necessary to maintain the temperature and it is necessary to continue supplying high power to the fixing heater and there is a possibility that the copying machine may be overloaded, the image forming mode for fixing power control is used as an index. However, the stapler is driven after the set number of images have been formed and the fixing target temperature is lowered to the standby target temperature, and the fixing power consumption is significantly reduced. There is no risk of becoming. Therefore, whether or not to use the stapler is excluded from the index for distinguishing the image forming mode for fixing power control.

  The power consumption pattern according to the operation stroke in each of the image forming modes 1 to 6 is, for example, as shown in Table 2 below.

  Here, “standby” is a state of waiting for an image forming instruction that can immediately proceed to start image forming if there is an image forming start instruction, and the fixing temperature (target temperature) is higher than the fixing temperature at the time of actual fixing. Low but relatively high. However, since there is no heat removal by the image forming paper, the input power to the fixing heater 123c is low. In the case of copying, “image formation” is an image formation process including from the scanner driving to the completion of transfer, and in the case of printing without printing the original (printing), it is an image formation process including from the start of feeding to the completion of transfer. is there. “Paper discharge” is the finisher operation period, and “after the final paper discharge” is the period for finishing the set number of sheets and finishing the sorting by the finisher when the finisher is used, and driving the stapler. . When the finisher is not used, it is a period in which the image formation and paper discharge for the set number of sheets are completed. Since the image forming modes 1 and 4 do not use a finisher, power consumption in “paper discharge” and “after the last paper discharge” is small. In image forming modes 2 and 5 that use the finisher but do not use the puncher, the power consumption of 50 W due to the paper transport and sorting by the finisher is added to the power of the “paper discharge”, and whether or not the stapler is used, “After paper” adds 50 W of power consumption by the stapler. Further, in the image forming modes 3 and 6 using the finisher and the puncher, the power consumption 50 W due to the paper conveyance and sorting by the finisher and the temporary power consumption 50 W due to the puncher are added to the power of “paper discharge”, and the stapler is used. Regardless of whether or not is used, the power consumption of 50 W by the stapler is added “after the last paper discharge”.

  In step 66c of FIG. 8, the CPU 85a of the DSP 85 can subtract the power of the power consumption pattern according to the operation process shown in Table 2 from the predetermined usable power upper limit value 1500W and input the obtained difference value to the fixing heater. Is written into the RAM 85c as a simple power pattern. The power pattern that can be input to the fixing heater according to the operation process is shown in Table 3 below.

  In the process of “after the last paper discharge” (FIG. 2), since the target temperature of the fixing heater is lowered to the standby value, the fixing heater input power is reduced as in the standby state. Therefore, the electric power that can be input to the fixing heater “after the last paper discharge” is the same as that in the “standby” process. That is, “after the last paper discharge” is deleted from the power pattern that can be input to the fixing heater, and the “after the last paper discharge” process is handled in the same manner as the “standby” process.

  Next, the CPU 85a of the DSP 85 executes "fixing temperature control" 79, which is the 5V and 24V output voltage control and output abnormality of the first and second power supply circuits and the energization control of the heater driver PC3 in steps 67 to 79 of FIG. To do. This control is collectively referred to as “overall control”. Even during this “overall control”, when the timer Ts expires, a timer Ts interrupt (TSI in FIG. 9) is executed. In the “overall control” (steps 67 to 79 in FIG. 8), the data in the register CAR that is cleared to 0 in step 21 of the timer Ts interrupt (TSI in FIG. 9) is referred to (67). "(The total control" has not been completed since the completion of the timer Ts interrupt), the "total control" execution count CNR is incremented by 1 (68), and the count value CNR becomes 5. Is initialized to 0 (69, 70), and "5V voltage control" (72) is executed when CNR = 0, corresponding to the count value CNR. When CNR = 1, 2, 3 or 4, “5V current abnormality control” (74), “24V voltage control” (76), “24V current abnormality control” (78) or “fixing temperature control” (79), respectively. Proceed to When the “overall control” is passed once, 1 (the timer Ts interrupt is not executed after completing the “overall control”) is written in the register CAR.

  Since the data in the register CAR is manipulated as 0 and 1 as described above, and it is determined in step 67 whether or not to proceed to “overall control”, when the timer Ts interrupt is completed, the above “ It is necessary to start one of the five types of control in “Overall Control”, complete it, and then complete one timer Ts interrupt. It does not initiate another control. Therefore, each of the five types of control in the “overall control” described above is repeatedly executed at a cycle of 5 Ts or more.

  In “5V voltage control” (72) in FIG. 8, the CPU 85a sets the channel number of the A / D converter 85i. 0, the output voltage V1 of the first power supply circuit PC1 is A / D converted and read, and whether it is equal to or higher than the set value Rf5VU (abnormal overvoltage) or lower than the set value Rf5VL (abnormal undervoltage) To check. If it is less than the set value Rf5VU and exceeds Rf5VL, that is, within the appropriate range, the error amount for 5V of the output voltage data read this time is calculated, and the error amount is converted into a PWM pulse duty. The prescribed PWM1 data is calculated, updated and written in the PWM1 register set in the CPU 85a or RAM 85c, and the data in the PWM1 register is written in the PWM1 pulse generation control register of the pulse generator 85e. As a result, the PWM pulse output from the pulse generator 85e to the pulse output port PWM1 changes to a duty for reducing the error amount of the output voltage to zero. This is feedback control of the output voltage of the first power supply circuit PC1.

  When the output voltage of the first power supply circuit PC1 is the set value Rf5VU or more or Rf5VL or less, that is, when the voltage is abnormal, the CPU 85a writes the data of the PWM duty 0% to the PWM1 register, the PWM2 register, and the PWM3 register. As a result, all the pulse outputs (PWM1 to PWM3) of the pulse generator 85e are stopped, and the FET1 of the first power supply circuit PC1, the FET2 of the second power supply circuit PC2 and the triac TR of the heater driver PC3 are all turned off. Next, the CPU 85a prohibits all interrupts permitted to itself. As a result, the DSP 85 stops operating until the AC voltage (switch SWap) is cut off once and turned on again, and the first power supply circuit PC1, the second power supply circuit PC2 and the heater driver PC3 stop operating and output. Disappears.

  In “5V current abnormality control” (74) in FIG. 8, the CPU 85a sets the channel number of the A / D converter 85i. The output current I1 of one first power supply circuit PC1 is read, and it is checked whether it is equal to or higher than a set value Rf5ViU (overcurrent abnormality) or Rf5ViL (low current abnormality). If so, then the CPU 85a writes the data of the PWM duty 0% into the PWM1 register, the PWM2 register and the PWM3 register. As a result, all the pulse outputs (PWM1 to PWM3) of the pulse generator 85e are stopped, and the FET1 of the first power supply circuit PC1, the FET2 of the second power supply circuit PC2 and the triac TR of the heater driver PC3 are turned off. Next, the CPU 85a prohibits all interrupts permitted to itself.

  The content of “24V voltage control” (76) in FIG. 8 is the same as that of the “5V voltage control” (72) described above, and the CPU 85a determines the channel number of the A / D converter 85i. The output voltage V2 of the second second power supply circuit PC2 is read, and the duty of the PWM2 pulse applied to the driver FET2 of the second power supply circuit PC2 is similarly feedback-controlled so that it is set to the set value 24V. If the output voltage V2 of the second power supply circuit PC2 is an overvoltage abnormality (output voltage is Rf24VU or more) or a low voltage abnormality (Rf24VL or less), the CPU 85 of the DSP 85 sets the PWM2 data to 0 (energization duty 0: energization stop). The driving of the second power supply circuit PC2 is stopped.

  The contents of “24V current abnormality control” (78) in FIG. 8 are substantially the same as the above-mentioned “5V current abnormality control” (74). In the “24V current abnormality control” (78), the CPU 85a sets the channel number of the A / D converter 85i. When the output current I2 of the second power supply circuit PC2 of No. 3 is read and it is an overcurrent abnormality (output current is Rf24iU or more) or a low current abnormality (Rf24iL or less), the PWM2 data is set to zero. That is, the driving of the second power supply circuit PC2 is stopped.

  Please refer to FIG. In response to the timer Ts time-over, the CPU 85a of the DSP 85 proceeds to the “timer interrupt” (TSI) shown in FIG. 9, and first restarts the timer Ts to determine the time until the next timer Ts interrupt ( 20). Then, the register CAR is cleared (21), and the current interrupt process is terminated.

  FIG. 10 shows the contents of “fixing temperature control” (79) shown in FIG. Here, the CPU 85a determines the current operation state based on the image formation mode data and input / output signals (start, set number of image formation completion, finisher operation signal) of the MPU 51 (FIG. 3) received by the communication interruption and operates. Process data is generated (30). Here, the process from receiving the start signal to receiving a set number of image forming completion signals is determined as an “image forming” process, and operation process data representing it is generated. In the image forming modes 2, 3, 5 and 6 using the finisher, it is determined that the process from receiving the set number of image forming completion signal to receiving the finisher processing completion signal is the “paper discharge” process, and the operation process representing it. When data is generated and a finisher processing completion signal is received, it is determined as a “standby” stroke, and operation stroke data representing it is generated. In the image forming modes 1 and 4 that do not use the finisher, when a set number of image forming completion signals are received, it is determined as a “standby” process and operation process data representing it is generated.

  Next, the CPU 85a, in the power supply pattern that can be applied to the fixing heater written in the RAM 85c in Step 66c (FIG. 8) (Table 3), the power that can be input for the operation process determined this time in the current imaging mode. The value is read out to be used power limit RMp (31). Next, the input power SPa necessary for matching the detected temperature of the thermistor TH with the target temperature received from the MPU 51 by communication interruption is calculated (32), and input when the calculated power SPa exceeds the use power limit RMp. The power is changed (suppressed) to the power usage limit RMp (33, 34), and the input power SPa is converted into PWM data PWM3d (35). In this embodiment, the values that can be taken by the PWM data PWM3d are from duty 0% (cycle: 10 half-waves of AC input, conduction half-wave number 0, 0 W) to duty 10% (cycle: 10 half-waves of AC input, conduction). The input power SPa is less than or equal to the input power SPa and is less than the input power SPa because the duty is up to 100% (period: 10 half waves of AC input, conduction half wave number 10,1000 W) in steps of half wave number 1,100 W). It is converted into duty data PWM3d that provides power consumption (W) closest to SPa. The duty data PWM3d obtained by the conversion is output to the PWM pulse generator 85o (36). The PWM pulse generator 85o holds the given duty data PWM3d in the input register. When the period of the PWM pulse currently being output ends, the PWM pulse generator 85o starts the PWM pulse output of the duty data PWM3d given this time, and newly starts the duty data. Until PWM is output, PWM pulse output with the same duty is repeated.

  The hardware configuration of the second embodiment is the same as that of the first embodiment described above, but the content of the fixing temperature control executed by the CPU 85a of the DSP 85 of the second embodiment is slightly different. In step 66b shown in FIG. 8, the CPU 85a of the DSP 85 of the second embodiment obtains an executable image forming mode and power consumption group (components and their power consumption) corresponding to the system configuration of the copying machine from the printer controller 60. When saved in the RAM, as indicated by a two-dot chain line block 66ca in FIG. 8, the entire copying machine excludes the fixing heater power consumption, and stands by, image forming, and paper discharge operation strokes for each image forming mode. Thus, the power consumption of the entire copying machine, excluding the fixing heater power consumption, is calculated, and then the calculated power consumption (upper limit power) is converted into a required duty Rpwm. Also in this embodiment, the usable duty is in increments of 10%. Therefore, the duty for supplying the closest electric power below the calculated upper limit electric power is set as a required duty Rpwm and written in the RAM 85c (66ca).

  FIG. 11 shows the content of “fixing temperature control” (79a) executed by the CPU 85a of the DSP 85 of the second embodiment. Also in the second embodiment, the CPU 85a, as in the first embodiment, is based on the image forming mode data and input / output signals (start, set number of image forming completion, finisher operation signal) received by the communication interrupt. The operation state data is generated by determining the current operation state (30a). Next, the CPU 85a reads out the duty data addressed to the operation stroke determined this time in the current image forming mode in the duty pattern (Rpwm group) written in the RAM 85c in step 66ca (FIG. 8), and uses the duty cycle. The limit Rpwm is set (31a). Next, a duty Spwm required to match the detected temperature of the thermistor TH with the target temperature received from the MPU 51 by communication interruption is calculated (32a). Spwm is changed (suppressed) to use duty limit Rpwm (33a, 34a), and the required duty Spwm is changed to 10% increments and output to PWM pulse generator 85o (36a). The PWM pulse generator 85o holds the given duty data PWM3d in the input register. When the period of the PWM pulse currently being output ends, the PWM pulse generator 85o starts the PWM pulse output of the duty data PWM3d given this time, and newly starts the duty data. Until PWM is output, PWM pulse output with the same duty is repeated.

1 is a front view showing an external appearance of a multi-function copying machine according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating an outline of an image forming mechanism of the printer 100 illustrated in FIG. 1. FIG. 2 is a block diagram showing a system configuration of an electric system of the copying machine shown in FIG. 1. It is a block diagram which shows the outline | summary of the power supply circuit on the power supply device 80 shown in FIG. FIG. 5 is an electric circuit diagram showing a circuit configuration of first and second power supply circuits PC1 and PC2 shown in FIG. 4. It is a block diagram which shows the electric system of DSP85 shown in FIG. 5 is a flowchart showing an outline of processing for starting a copier immediately after a main power switch SWap is turned on in the power supply device 80 and the printer controller 60 shown in FIG. 4. It is a flowchart which shows the content of the power supply circuit control of CPU85a of DSP85 shown in FIG. It is a flowchart which shows the content of the interruption process in response to the time over of Ts time limit timer of CPU85a of DSP85 shown in FIG. FIG. 9 is a flowchart showing the content of “fixing temperature control” (79) shown in FIG. 8. FIG. It is a flowchart which shows the content of the "fixing temperature control" (79a) of 2nd Example of this invention. FIG. 6 is an AC voltage waveform diagram showing, with a solid line, an AC voltage supplied to the fixing heater by the triac TR shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101: Photoconductor belt 102,103: Rotating roller 104: Charging charger 105: Laser exposure device 106: Color developing device 107: Cleaning blade 109: Intermediate transfer belt 110-112: Rotating roller 113: Bias roller 114: Transfer roller 115: Cleaning device 116: Paper feed table 117: Paper feed roller 118a, 118b: Transport roller pair 119a, 119b: Registration roller pair 120: Fixing device 121a, 121b: Paper discharge roller pair 122: Paper discharge stack unit TR: Triac

Claims (6)

In an image forming apparatus comprising an image forming means for forming a visible image on a photoconductor, a means for transferring the visible image to a paper, and a fixing means for heating the paper to which the visible image is transferred.
In the image forming apparatus, a power supply duty for supplying power to the fixing unit is less than or equal to an upper limit value of fixing unit input power that decreases or increases in response to an increase or decrease in load power excluding power input to the fixing unit. An image forming apparatus comprising power supply control means for controlling.   The power supply control means uses an image forming mode in which whether the image forming apparatus is a single color image or a full color image and whether or not a finisher is used as a mode classification index, and standby, image formation, and paper discharge as status classification indices. 2. The image forming apparatus according to claim 1, wherein a power supply duty for supplying power to the fixing unit is controlled to be equal to or less than an upper limit value of the fixing unit input power addressed to the image forming mode and the operation process in correspondence with the operation process. .   The power supply control unit calculates a fixing unit input power upper limit value addressed to the image forming mode and the operation stroke based on standby power and maximum power consumption of a power consuming device of the image forming apparatus, and stores the upper limit value in a memory. The image forming apparatus according to claim 2.   The fixing unit includes a temperature sensor, and the power supply control unit calculates a power supply duty for adjusting a temperature detected by the temperature sensor to a target temperature, and stores the current duty in a current image forming mode and an operation process. 4. The image formation according to claim 3, wherein the upper limit value of the fixing unit input power addressed thereto is converted into a power supply duty, and power is supplied to the fixing unit at a low power supply duty among the calculated power supply duty and the converted power supply duty. apparatus.   The power supply control unit calculates a fixing unit input power upper limit value assigned to the image forming mode and the operation stroke based on standby power and maximum power consumption of the power consuming device of the image forming apparatus, and calculates the calculated fixing unit input The image forming apparatus according to claim 2, wherein the power upper limit value is converted into a power supply duty corresponding to the power upper limit value and stored in the memory. The fixing unit includes a temperature sensor, and the power supply control unit calculates a power supply duty for adjusting a temperature detected by the temperature sensor to a target temperature, and holds the current image forming mode and operation process stored in the memory. The image forming apparatus according to claim 5, wherein electric power is supplied to the fixing unit at a low power supply duty among the assigned power supply duty and the calculated power supply duty.

Images