JPH0210950B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-fixing type copying machine, and particularly to a power control method in a copying machine in which power is supplied to an exposure lamp and a fixing heater by controlling the conduction phase angle of AC power. Generally, in a copying machine, one copy is completed through the processes of charging, exposure, development, transfer, and fixing, but in this process, the power consumption is relatively large in copying machines using heat fixing method. These are an exposure lamp and a fixing heater. By the way, in filament lamps such as exposure lamps and heater lamps used as fixing heaters, the filament resistance before lighting is much smaller than that during lighting, so if the rated voltage is applied when lighting the lamp, the resistance will be approximately 10 times the rated voltage. A rush current of the above amount flows. As a result, not only the filament deteriorates and the life of the lamp is shortened, but also a semiconductor AC switch such as a triax in a power control circuit may be destroyed. Furthermore, in recent years, the control section of copying machines has been increasingly constructed using microcomputers, etc., but the DC power supply for this control section is generally 5V.
Or, it is around 12V, and unless the fluctuation range is kept within ±5%, the control unit cannot operate stably. However, when the aforementioned large inrush current occurs, the voltage of the DC power supply may fluctuate by more than ±5% or be momentarily interrupted due to its influence, causing damage to data stored in memory, latch data of I/O devices, etc. may be erased. Therefore, in the past, by adding a soft start circuit mainly consisting of a CR time constant circuit to the power control circuit, the amount of power supplied to the exposure lamp or fixing heater was gradually increased, and a large inrush current was generated when the lamp was turned on. I was trying not to. However, the above-mentioned soft start circuit works effectively when the copying machine is operated first thing in the morning or when the copying interval is long because the filament is cold, but it works effectively when the copying machine is operated first thing in the morning or when the copying interval is long, but it does not work effectively when the copying machine is operated first thing in the morning or when the copying interval is long because the filament is cold. When the exposure lamp is repeatedly turned on and off periodically, there are the following drawbacks. In other words, once a lamp is lit, the filament resistance gradually increases due to the residual heat from the second time onwards, and the inrush current during lighting becomes smaller.
It would be possible to shorten the soft start time, but since the conventional soft start circuit has a constant time constant, it is not possible to perform control appropriate to the actual phenomenon described above. Further, in a copying machine, an exposure lamp is turned on at a predetermined timing during an exposure process, and a fixing heater is turned on and off irregularly according to the temperature detected by a temperature sensor installed near the fixing heater. Therefore, the exposure lamp and fixing heater may turn on at the same time, but if they are turned on at the same time, the inrush current from both will be superimposed and a large amount of current will instantly flow into the AC power line, so the DC Not only does the above-mentioned trouble occur with the power supply, but the illuminance of the exposure lamp also decreases, resulting in a significant deterioration in copy quality due to insufficient exposure. Therefore, as seen in, for example, JP-A No. 53-37420 and JP-A-55-79477, the fixing heater is not turned on while the exposure lamp is on, and the timing of operation of both (power-on period) is It is proposed to avoid overlapping. However, if this is done, the operating timing of the fusing heater is unnecessarily restricted, and there is a risk that the temperature cannot be maintained above the predetermined fusing temperature, especially during continuous copying, resulting in uneven fusing. In order to avoid this, there are problems such as the need to slow down the copy speed. This invention was made in view of the above points,
By eliminating all problems caused by the rush current when the exposure lamp and fixing heater are turned on as described above, and by making it possible to operate the exposure lamp and fixing heater efficiently according to the operating conditions, the continuous copy speed can be improved. The purpose is to prevent deterioration and uneven fixation. In order to achieve the above object, the present invention provides a copying machine in which power is supplied to an exposure lamp and a fixing heater by controlling the conduction phase angle of AC power.
It has a plurality of soft start modes each having different power supply increasing slopes and rise times and gradually transitioning the power supply to the exposure lamp and the fixing heater from a small conduction phase angle to full power,
Selecting one of the plurality of soft start modes according to the respective operating states of the exposure lamp and the fixing heater to control the power supply after the exposure lamp and the fixing heater are turned on, and turning on the exposure lamp and the fixing heater. If the times overlap, a power control method is provided in which the time when the fixing heater is turned on is delayed by a certain period of time and the fixing heater is turned on after the exposure lamp is turned on. Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a control section of a copying machine to which the present invention is applied. In the figure, a microcomputer (hereinafter referred to as
(abbreviated as "microcomputer") 1 is an 8-bit one-chip microcomputer that includes a CPU (central processing unit), data memory (RAM), and three 8-bit parallel I/O ports (ports P ₀ , P ₁ , P ₂ ), an 8-bit counter ( _T1 terminal) that can operate as a timer or event counter, a test terminal _T0 , an interrupt terminal, etc. This microcomputer 1 performs control related to the present invention, which will be described later, as well as sequence control of each load as shown in the drawing of the copying machine through ports _P10 to _P10 of the memory/IO element 2 connected to port P1 and port _P0 . It is now possible to do so via _P12 . In addition, memory/
IO element 2 has program memory (EP ROM) and
It has a built-in 16-bit I/O port and is controlled by a control signal output from terminal _CL1 of microcomputer 1. 3 is a CMOS buffer group, 4 is a resistance group,
5 is a group of NPN type Darlington transistors, and 6 is a group of open collector inverters. Also,
Reference numeral 7 designates a CMOS inverter, and its output energizes a high-speed solid state relay (SSR) 8 to turn on a heater lamp 9 as a fixing heater. Ports _P14 to _P17 of memory/IO element 2 have C
A MOS AND/OR selector 10 is connected, and this AND/OR selector 10 has its terminals X,
Port P ₂₀ of memory/IO element 2 input to Y,
In response to the pulse signal from P ₂₁ , input information from the switch group 12 described below is alternately input into the microcomputer 1 via the memory/IO element 2, four at a time. Input terminal X ₁ of this AND/OR selector 10 ~
+5V is applied to each of X ₄ , Y ₁ to Y ₄ via a pull-up resistor group 11, and when the switch group 12 is turned on, a low level “L” input signal is input to the AND/OR selector 10. be done. The switches in the switch group 12 include, for example, a switch for counting up and counting down the number of copies, a lighter switch and a darker switch for setting copy density, a print start switch, a multi-copy switch,
These include clear/stop switches and interrupt copy switches. The count up switch and count down switch count up or down each time the switch is pressed, or count up or down by counting a predetermined pulse signal while the switch is pressed. Further, the writer switch and the darker switch are configured such that the copy density setting value is sequentially shifted to the lighter or darker side while the switch is pressed. Furthermore, a multi-copy switch is a switch that allows multiple copies to be made regardless of input data, and an interrupt copy switch is a switch that retains input data that is being copied when another copy is being made during copying. This is a switch for continuing the copy that was being copied first when another copy is finished. Ports P ₂₀ to _{P 23} of the memory/IO element 2 are connected via a decoder/driver circuit 13 to a 7-segment display 14 for displaying the number of copies and a 7-segment display 14 for displaying the temperature.
The segment display unit 15 is connected, and C from ports P ₂₄ and P ₂₅ of the memory/IO element 2, respectively.
A dynamic scan is displayed by a scanning pulse outputted through a MOS buffer, a resistor, and an NPN type Darlington transistor. Although the displays 14 and 15 have one digit in FIG. 1, they can have multiple digits if necessary. In _addition , as shown in _{the figure} , an open collector inverter, a _resistor , and a _C
MOS inverter (indicated by symbol a in the figure), resistor,
LED group 1 for displaying various information via PNP type Darlington transistor (indicated by symbol b in the figure)
6, 17, and 18 are connected, and dynamic scan display is performed by scanning pulses output from ports P ₁₃ , P ₂₆ , and P ₂₇ of the memory/IO element 2. Each LED of the LED group 16 includes, for example, a green lamp indicating that copying is possible, a red lamp indicating that copying is not possible, a lamp indicating that the multi-copy switch is on,
It also serves as a lamp indicating that the interrupt copy switch is on. Furthermore, each LED in LED group 17 serves as a lamp that indicates four levels of copy density, and LED group 18
For example, each LED indicates a toner shortage,
It serves as a lamp that indicates that the transfer paper is out, a lamp that indicates that a jam has occurred, and a lamp that prompts replacement of the photoreceptor. Note that ports P ₂₀ to _{P 23} of memory/IO element 2 are
As shown in the figure, since it is connected to the AND/OR selector 10, the decoder/driver circuit 13, and the LED groups 16 to 18, time-division control is performed. An 8-channel A/D converter 19 is connected to the port _P2 of the microcomputer 1, and the microcomputer receives the signal from the terminal _CL2 of the microcomputer 1 via the bidirectional bus port. After reading the operation commands from 1 and converting the data input to each channel CH ₀ to _{CH 7} , the conversion results are sequentially output to the microcomputer 1.
Note that binary data can also be input to this A/D converter 19. Channels CH ₀ , CH ₁ of this A/D converter 19
A temperature detection signal from a temperature sensor such as a thermistor (not shown) provided near the heater lamp 9, and a peak value detection signal from a circuit for detecting the peak value of the AC load voltage shown in FIG. A/D conversion is performed. The temperature information that is the conversion result is used for control related to the present invention, which will be described later, and is also used in the 7-segment display 1 for temperature display.
5 is displayed. In addition, the peak value information is divided by √2 in the microcomputer 1 and converted into effective value information (effective value = peak value / √2), and then compared with the reference value to calculate the deviation. Used to compensate AC load voltage according to the result (regulator function). Note that the circuit for detecting the peak value of the AC load voltage shown in FIG. The pulsating wave is then output as a sampling signal from microcontroller 1 at the appropriate time.
A peak hold circuit 22 operated by Sp detects the peak value and outputs the peak value. Returning to FIG. 1, the other channels CH ₂ to _{CH 7} of the A/D converter 19 are connected via a CMOS inverter group 23 whose input side is set to +12V by a pull-up resistor group 24 as shown in the figure. Various sensor signals are input. Note that these various sensor signals are binary signals of "1" or "0". Port P ₂ of microcontroller 1 has a non-volatile port addressed by the address signal from terminal CL ₃ .
A RAM 25 is also connected so that data on the number of copies and various diagnostic data for the copying machine can be stored even when the power is turned off. The interrupt terminal of the microcomputer 1 is connected to the encoder 2 via the Schmitt trigger inverter 26.
Timing pulses from 7 are input, and counting for sequence control is done by the interrupt routine program. The encoder 27 has a structure in which a light emitting diode 27b and a phototransistor 27c are arranged facing each other, sandwiching a slit disk 27a which is rotated in synchronization with the rotation of the photoreceptor, and the output timing pulse is The pulse interval is about 5 msec. Furthermore, a timing start pulse obtained via an inverter 31 by detecting the start position mark 29 on the photoreceptor 28 with a reflective photoelectric sensor 30 consisting of a light emitting diode and a phototransistor is connected to the T ₀ terminal. It is now being entered. When this timing start pulse is input to the terminal _T0 , the microcomputer 1 starts sequence control. This T ₀ terminal is a subroutine that is called by two instructions of the microcomputer 1 by jumping the level “0” or level “1” to a specific address of the ROM in the memory/IO element 2 according to each instruction. It can be tested by Therefore, it can be determined whether a timing start pulse has been input to the T ₀ terminal. Furthermore, the zero-cross pulse of the AC power supply voltage is input to the T1 terminal of the microcomputer ₁ . That is, a 10V AC voltage obtained by stepping down the voltage by a transformer (not shown) is full-wave rectified by a full-wave rectifier circuit 32, and then the light-emitting diode 33 is
to be applied. In this way, the light emitting diode 33 is turned off near the AC zero-crossing point, and turned on to emit light at other times, so that the phototransistor 34 constituting the photocoupler is turned off each time near the AC zero-crossing point. Therefore, the input side of the inverter 35 becomes high level "1" at each zero cross point, and a zero cross pulse that becomes low level "0" at each AC zero cross point is generated on the output side, and this zero cross pulse is applied to the _T1 terminal. is input. The circuit inside the microcomputer 1 connected to this _T1 terminal is as shown in FIG. The counter 36 in this circuit is the microcomputer 1
If the internal clock pulse from the frequency divider 37 is input to the counter 36 by a specific command, it functions as a timer, and by another command, the external clock pulse is input to the counter 36 via the edge detection circuit 38.
If input to , it functions as an event counter. Therefore, here we will introduce the timer function and T ₁
Using the zero cross pulse input to the terminal,
It detects the frequency of the AC power input to the copying machine, and measures the firing timing required for power phase control of the exposure lamp and heater lamp 9 as a fixing heater, which will be described later. Similarly to the T ₀ terminal, the T ₁ terminal can be set to level “0” or level “1” by two instructions from the microcomputer 1.
Since it can be tested according to each command, it can be determined whether a zero-crossing pulse has been input to the _T1 terminal, and the counter 36 can be preset to a necessary value (time-up value) by a program. Therefore, when detecting the frequency of the AC power supply, the counter 36, which functions as a timer, is activated when a zero-cross pulse is input to the _T1 terminal, and the counter 36, which functions as a timer, is activated when the next zero-cross pulse is input. If the counter 36 is stopped, the count value of the counter 36 during that time is inversely proportional to the frequency, so that the frequency can be detected. For example, if the oscillation frequency ₀ of the crystal oscillator in the microcontroller 1 is 11MHz, the frequency of the clock pulse input to the frequency divider 37 in FIG. The frequency of its output pulse is 22.9KHz. Therefore, counter 36 is 1/22.9KHz=44μsec
It is incremented every time. Therefore, when the frequency of AC is 50Hz and 60Hz, the period of half cycle is 10msec and 8.3m respectively.
sec, the count value of the counter 36 is "227" for 50Hz and "189" for 60Hz. By storing these values in advance in the ROM of the memory/IO element 2 and comparing them with the counted value of the counter 36 in the microcomputer 1 at appropriate times, the frequency of the power supply input to the copying machine can be detected. Based on this detection result, ignition timing (phase control angle) data used for power phase control, which will be described later, is switched. In addition, when measuring the ignition timing required for power phase control, the counter 36 is activated every time a zero-crossing pulse is input to the _T1 terminal, and the time-up is performed at a predetermined point between zero-crossing pulses (half cycle of AC). If the time-up is detected, the heater lamp 9 in Fig. 1 will be activated.
It is possible to obtain the ignition timing of the SSR8 and the SSR for the exposure lamp (not shown). That is, as mentioned above, the time-up value can be preset in the counter 36 shown in FIG. An overflow occurs, the overflow flag 39 is set, and an interrupt request is generated. This interrupt request is logically ORed with an external interrupt request from the interrupt terminal, but if they occur at the same time, the external interrupt takes priority and waits until the interrupt processing is completed. Therefore, an interrupt request due to an overflow is permitted when the enable signal that is output when no external interrupt is generated is input to one input of the AND circuit 40, and when it is permitted, the memory An overflow occurrence detection routine stored at a specific address in the ROM of the /IO element 2 is called as a subroutine, and an overflow of the counter 36 can be detected. The detection result is then stored at a specific address. Note that overflow can also be checked by testing the overflow flag 39 using a conditional jump instruction. If the microcomputer 1 ignites the SSR 8 for the heater lamp 9 and the SSR for the exposure lamp at the time of overflow (ignition timing), desired power phase control can be performed. For example, the preset values of the counter 36 when measuring firing angles of 175°, 170°, 160°, and 150° in the soft start mode described below are as shown in the following table. In the following table, the switching between 50Hz and 60Hz is performed by the microcomputer 1 according to the frequency determination result described above.

[Table] Also, the preset values shown in the table are for counter 3.
6 is incremented every 44 μsec, and fractions are rounded off. Next, on the premise that the microcomputer 1 has the above-mentioned functions, details of the power control method according to the present invention will be explained with reference to flowcharts shown in FIGS. 4 to 12. First, before explaining the flowchart, the types of soft start modes in this embodiment will be described. (1) Soft start mode of heater lamp 9 H mode: Phase control of firing angles of 170° and 160° is performed for 0.5 seconds each. H mode: Phase control with firing angle of 170° is performed for 0.5 seconds. H mode: Phase control with firing angle of 175° for 0.3 seconds,
After performing phase control for firing angles of 170° and 160° for 0.25 seconds each, phase control for firing angle of 150° was performed for 0.2 seconds.
Do it in seconds. H mode: After performing phase control for firing angles of 170° and 160° for 0.2 seconds each, phase control for firing angle of 150° is performed for 0.1 seconds. (2) Exposure lamp soft start mode L mode: Phase control of firing angles of 175°, 170°, 160°, and 150° is performed for 0.1 seconds each. L mode: After performing phase control at a firing angle of 170° for 0.1 seconds, phase control at firing angles of 160° and 150° is performed for 0.05 seconds each. In each of the above modes, the degree of change in the firing angle is the power supply increasing gradient, and the total phase control time is the rise time. Further, among the flowcharts described below, the flowcharts shown in FIGS. 4 to 6 specifically show only the exposure process of the copying process for convenience of explanation. In Fig. 4, when the copying machine is powered on in STEP 1, the power frequency is monitored in STEP 2 by a program that is a subroutine of the method described above, and in STEP 3 it is set to 50Hz according to the monitoring result.
Or set a flag for 60Hz. Next, check the time the power was turned off in STEP 4. This check routine is executed by, for example, a program timer that is stored in the non-volatile memory (RAM) 25 shown in FIG. The measured time can now be accessed. Furthermore, in STEP 5, the temperature of the heater lamp 9 is monitored by checking the value obtained by converting the temperature detection signal output from the temperature sensor, which corresponds to the temperature of the heater lamp 9, into a digital signal by the A/D converter 19. do. Next, in STEP 6 and 7, check whether the power was turned off for more than 5 minutes and the temperature of the heater lamp 9.
Check whether the temperature is below 100℃. If the power has been off for more than 5 minutes and the temperature of the heater lamp 9 is below 100℃, proceed to STEP 8.
If the temperature is not below 100°C, skip to the H mode subroutine of STEP 9. In addition, if the heater lamp 9 is turned off for less than 5 minutes, the temperature of the heater lamp 9 should be at least 100℃.
Assuming that it is not as follows, skip to the H mode subroutine of STEP 9. The H mode subroutine is shown in FIG. That is, in STEP30, the H mode program is called from the ROM of the memory/IO element 2 shown in Figure 1, and in STEP31, the H mode program is called from the ROM of the memory/IO element 2 shown in
Perform a flag check of the frequency set by
Check whether the power frequency is 50Hz or 60Hz and check the memory/IO
The data (preset value of the counter 36) for measuring the firing timing for phase control in the ROM of the element 2 is switched. Next, in STEPs 32 and 33, power supply control is performed for 0.5 seconds by power phase control at a firing angle of 170° according to a program that is a subroutine of the phase control method described above. Then, after 0.5 seconds have elapsed, power supply control by power phase control with a firing angle of 160° is performed for 0.5 seconds at STEPs 34 and 35, and then the process returns to STEP 10 in FIG. The heater lamp 9 is preheated by performing power supply control in the soft start mode of the H mode, and even if the heater lamp 9 is turned on in STEP 10, a large rush current will not flow. In addition, the H mode subroutine consists of STEP36 to STEP39 as shown in Figure 8, and the firing angle
Power supply control is performed using 170° power phase control for 0.5 seconds, and after an appropriate soft start according to the residual heat state of the heater lamp 9,
Return to STEP 10 in Figure 4. Then, in STEP 10, the heater lamp 9 is turned on at full power (100%) by the zero crossfire so that the temperature of the heater lamp 9 quickly reaches the set temperature (for example, 200° C.). Next, in STEP 11, check whether the temperature of the heater lamp 9 has reached or exceeded the set temperature.
If not, repeat the control in STEP10,
If the temperature is higher than the set temperature, the heater lamp 9 is turned off, a reload signal is output in STEP 12 of FIG. 5, a green lamp indicating that copying is possible is turned on, and the process waits until the copy start switch is pressed in STEP 13. When the copy start switch is pressed, sequence control of the copy process is started in accordance with the number of timing pulses input to the interrupt terminal of the microcomputer 1 shown in FIG. Then, in STEP14, the exposure timing is checked, and if it is not the exposure timing, a charging process is executed according to a program not shown in the drawings, and if it is the exposure timing, the process proceeds to STEP15. In STEP 15, if the temperature of the heater lamp 9 has dropped by 5% or more of the set value, it is checked whether it should be turned on again.
Proceed to STEP17, and if it is the time to turn on, delay that point by, for example, 0.5 seconds in STEP16 so that the exposure lamp is turned on preferentially, and then proceed to STEP17. In STEP 17, it is checked whether the copy is the first copy and the operating status of the exposure lamp is checked. In this way, if it is the first copy, the exposure lamp is in a cold start state, and if the second or more copies are being made, the exposure lamp is in a residual heat state, so whether the copy is the first copy or not. By checking this, the operating status of the exposure lamp can be determined. If it is the first copy, the process skips to the L mode subroutine of STEP 18, and if it is the second or more, the process skips to the L mode subroutine of STEP 19. The L mode subroutine consists of STEP 40 to STEP 49 as shown in Fig. 9, and the firing angle is 175°,
Power supply control using power phase control of 170°, 160°, and 150° is performed for 0.1 seconds each, and when these power supply controls are completed, STEP 20 in Figure 5
to return to. By performing power supply control using the soft start mode of the L mode,
Even if the exposure lamp is preheated and turned on in STEP 20, a large rush current does not flow. The L mode subroutine consists of STEP 50 to STEP 57 as shown in Fig. 10, and after performing power supply control by power phase control at a firing angle of 170° for 0.1 seconds, the firing angle is changed to 160° and 150°. Power supply control is performed by power phase control for 0.05 seconds each, and after an appropriate soft start according to the residual heat state of the exposure lamp, STEP 20 in Figure 5
to return to. Then, in STEP 20, the exposure lamp is turned on, and effective value information is obtained from the information from the peak value detection circuit of the AC load voltage mentioned above so that the exposure lamp is turned on with the amount of light emitted according to the copy density setting value. Lighting control is performed by feedback control. Next, in STEP 21 of FIG. 6, monitor the temperature of the heater lamp 9 in the same way as STEP 5 of FIG.
In STEP 22, it is checked whether the monitored temperature is below 100°C, and an abnormality in the heater lamp 9 is detected. If the temperature of the heater lamp 9 is 100° C. or less, the red lamp indicating that copying is not allowed is turned on in STEP 23, and then the process skips to the H mode subroutine of STEP 24. The H mode subroutine consists of STEP 58 to STEP 67 as shown in Fig. 11.
Power supply control using 175° power phase control for 0.3 seconds.
After gradually preheating the heater lamp 9 by performing power supply control using power phase control at firing angles of 170° and 160° for 0.25 seconds each, and power supply control using power phase control at a firing angle of 150° for 0.2 seconds, Return to STEP 10 in Figure 4, and then proceed to STEP 10 and 11 described above. Also, in STEP 22, the temperature of heater lamp 9 is set to 100.
If it is checked that the temperature is not below ℃, the process advances to STEP 25 and the temperature of the heater lamp 9 reaches the set value of 5℃.
If the heater lamp 9 is in a state where it should be turned on again after dropping by more than %, or if the heater lamp 9 is in a state where it should be turned on in STEP 15,
Check whether more than 0.5 seconds have passed since the exposure lamp was turned on. If it is not the time when the heater lamp 9 should be turned on, the process directly proceeds to STEP 28, and if it is the time when the heater lamp 9 should be turned on, the process skips to the H mode subroutine of STEP 26. The H mode subroutine consists of STEP 68 to STEP 75 as shown in Figure 12.
Power supply control using 170° and 160° power phase control, respectively.
After 0.2 seconds, power supply control using power phase control with a firing angle of 150° was started for 0.1 seconds.
After gradually preheating the heater lamp 9 according to its residual heat state, the process returns to STEP 27 in FIG. Then, in STEP 27, the heater lamp 9 is turned on, and since it is now the copy lamp control time,
For example, if the heater lamp 9 is 1.2KW, the effective value information is obtained from the information from the AC load voltage peak value detection circuit mentioned above, and lighting control is performed using effective value feedback control so that its effective output is 800W. By doing so, the temperature of the heater lamp 9 is set to be, for example, between the set value and the set value + the set value x 5%. Then, after sequentially controlling the copy process other than charging and exposure in STEP 28,
In STEP 29, check whether the copy end flag is set. If it is not set, it is continuous copy mode, so return to STEP 14 in Figure 5. If it is set, copying is finished, so see Figure 5.
Return to STEP 13 and wait until the copy start switch is pressed again. Note that even during the sequence control of the copy process in STEP 28, the temperature of the heater lamp 9 is monitored at appropriate times, and if the heater temperature drops, the heater lamp 9 is turned on after preheating by soft start. As described above, by performing the power control according to the present invention, an appropriate soft start is performed according to the respective operating states of the exposure lamp and fixing heater, so generation of rush current can be efficiently prevented, and the exposure Since the times at which the lamp and the fixing heater are turned on do not overlap, generation of rush current can also be prevented. In addition, in the above embodiment, if the filament resistance values of the heater lamp and exposure lamp are detected and the soft start mode is selected according to the detection result, the soft start mode can be more appropriately adapted to the respective operating conditions. Control becomes possible. In addition, the H mode in the above embodiment,
, and the L mode, the combination of the power supply increasing slope and rise time can of course be changed as appropriate, and the types of soft start modes can also be increased. Incidentally, FIG. 13 shows an example of a timing chart of sequence control in a copying machine to which the present invention is applied. The timing chart shown in Fig. 13 is for two-sheet copying, and the timing chart shown in Fig. 13 is for at least 0.5 seconds from the timings T ₁ and T ₂ when the exposure lamps shown in Fig. Then, for a certain period (0.5 seconds) immediately before the exposure lamp turns on, microcontroller 1 turns on heater lamp 9.
A trigger inhibit signal is generated to prohibit turning on the heater lamp 9, thereby preventing the heater lamp 9 from turning on during this period. As explained above, according to the power control method according to the present invention, one of a plurality of soft start modes consisting of a predetermined power supply increase gradient and rise time is selected according to the operating states of the exposure lamp and the fixing heater. Then, according to the selected soft start mode, the amount of power supplied to the exposure lamp and fixing heater is gradually increased to preheat each, and if the exposure lamp and fixing heater are turned on at the same time, the fixing heater is turned on. By delaying the turning on of the exposure lamp by a certain period of time and turning on the fixing heater after the exposure lamp is turned on, it is possible to completely eliminate the generation of rush current in the AC load system of the copying machine. Since the soft start mode is changed according to the operating status of the fuser heater, the exposure lamp and fuser heater can operate efficiently and efficiently with the minimum necessary startup period without providing an unnecessarily long startup period during continuous copying. be able to. Additionally, even if the exposure lamp and fuser heater are turned on at the same time, the fuser heater can be turned on immediately after the exposure lamp is turned on (while it is on) by simply delaying the time when the fuser heater is turned on. Can be done. Therefore, problems such as shortened lamp life and damage to semiconductor switches due to the generation of rush current, and malfunction of control circuits due to voltage fluctuations can be eliminated, and furthermore, problems such as a decrease in continuous copying speed and a decrease in fusing temperature can be eliminated. It is also possible to prevent the occurrence of uneven fixing due to the drop.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control section of a copying machine to which the present invention is applied. FIG. 2 is a circuit diagram for detecting the peak value of AC load voltage. Figure 3 shows
FIG. 2 is a block diagram of a counter section built into a microcomputer connected to the _T1 terminal. 4 to 12 are flowcharts of programs executed by a microcomputer to control according to the present invention. FIG. 13 is a timing chart showing an example of sequence control in a copying machine to which the present invention is applied. 1...Microcomputer, 2...Memory/
IO element, 8... solid state relay (SSR), 9... heater lamp, 22... peak hold circuit, 27... encoder, 36... counter.

Claims (1)

[Claims] 1. In a copying machine in which power is supplied to the exposure lamp and the fixing heater by controlling the conduction phase angle of AC power, the power supply increasing gradient and rise time are different from each other, and the power supply to the exposure lamp and the fixing heater is controlled at a small conduction phase angle. The exposure lamp and the fixing heater each have a plurality of soft start modes in which the power is gradually shifted to full power, and one of the plurality of soft start modes is selected depending on the operating state of the exposure lamp and the fixing heater. In addition, if the exposure lamp and the fixing heater are turned on at the same time, the fixing heater is turned on after the exposure lamp is turned on by delaying the time at which the fixing heater is turned on by a certain period of time. A power control method for a copying machine characterized by: