JPS5933480A - Heater driving device of fixation device for copying machine - Google Patents

Abstract

PURPOSE:To prevent a noise and suppress a rush current, by providing plural heaters different in power consumption and driving them with a prescribed voltage after driving auxiliarily them in order from the heater of the least power consumption with a voltage lower than the prescribed voltage. CONSTITUTION:When a switch 27 is turned on to supply electric power, a driving signal is outputted from a control part 12, and a 24-volt voltage is applied to the first heater 11a for a heat roll through a timer 13 or the like, and the heater 11a is heated. The second timer 15 is turned on through a delay circuit 14 after a prescribed time, and the 24-volt voltage is applied to the second heater 11b. Simultaneously, the second delay circuit 16 is turned on, and the third delay circuit 17 is turned on after a prescribed time, and a 100-volt voltage is applied to the first heater 11a and the second heater 11b, whose heater resistances are increased already, in order. Since heaters are driven by the prescribed voltage after driving them auxiliarily by a lower voltage to increase heater resistances, the noise is prevented, and the rush current is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heater drive device for a fuser for a copying machine that suppresses rush current without generating noise.

As a heater drive device for a fuser for a copying machine, for example, the power of the heater π1 is controlled by controlling the heater so that the heater is turned on only when the instantaneous value of the sine wave cloth 1 source voltage is below a predetermined level. There is something.

According to the heater drive device of a fuser for a copying machine, rush current cannot be suppressed by a zero-cross drive circuit that turns on the heater at the zero-cross point where the sine wave power supply voltage becomes zero when the capacity of the heater becomes large. can be suppressed to a certain extent, so flickering of indoor lighting equipment such as fluorescent lights can be prevented.

However, in the heater drive device of the fuser for copying machines, the heater is turned on and off according to the phase angle of the sine wave power supply voltage, which may generate noise that may cause radio wave interference or malfunction of the equipment. There is.

The present invention has been made in view of the above, and in order to suppress rush current without generating noise,
A fixing device for a copying machine in which a plurality of heaters having different power consumptions are provided, and the heaters are pre-driven at a lower voltage in descending order of power consumption, increasing the heater resistance, and then driven at a predetermined voltage. The present invention provides a heater driving device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A heater driving device for a fuser for a copying machine according to the present invention will be described in detail below.

FIG. 1 shows an embodiment of the present invention, in which a console 1 having various operations, a display section, etc., and a platen 3 on which a document 2 is placed are provided at the top of the copying machine. Inside the copier,
An optical system 4 that scans the original 2, a photosensitive drum 5 that is exposed to light based on the exposure of the optical system 4, a charging section 6, a developing section 7, a transfer section 8, and a cleaner section 9 arranged around the photosensitive drum 5. and a paper feed tray 10 a e containing copy paper.
10b, a fixing section 11 for fixing the transferred copy paper, and a control section 12 (microcomputer) for controlling the operation of the copying machine.

At the output end of the control unit 12, there is a first timer that is turned on for a predetermined time TI when the heater drive signal is output (for example, a mono multi-by-play is delayed by a predetermined time T!, and the heater drive signal is no longer output). Turn on until the first
a delay circuit 14 (time T1 is set to the time necessary for the heater resistance to increase to a resistance value that prevents rush current, and time T1 is set to T1); and a first delay circuit 14. a second timer 15 (for example, composed of a mono-multivibrator, and time T3 is set to a time at which the heater resistance increases to a value that prevents rush current), which turns on for a predetermined time T when the heater is turned on; second and third delay circuits 16 and 17 that turn on with a delay of time (T2 + Ts) and time (T+++Tg + T4) after the drive signal is output, and turn off when the drive signal is no longer output; , first and second
When the timer 13.15 is on, the first and second drive circuits 18.19 detect the zero cross point of the power supply voltage and turn on, outputting the first and second heater activation signals.
When the second and third delay circuits 16 and 17 are on, they detect the zero cross point of the power supply voltage and turn on.
and a third and fourth heater that outputs a fourth heater activation signal.
A drive circuit 20.21 is provided. In addition to this configuration, the first to fourth triacs 22, 23, 24°2 are turned on based on the first to fourth heater activation signals.
5. The power supply unit includes an AC 100/root power supply 28 and a turn-on switch 27 that supplies power to the transformer 26.
The first triac 22 is a first heater 11a which will be described later.
(for example, 450 watts) with a voltage of 24 delts applied,
The second triac 23 is a second heater 1lb which will be described later.
(for example, 700 watts) and apply a voltage of 24 volts,
Also, the third and fourth triacs 24.25 are
and second heater 11a.

Apply a voltage of 100 melt to 11b.

Furthermore, the fixing unit 11 is composed of a heating roll llc that incorporates the aforementioned heaters 11a*11b, and a pressure roll lid that presses the copy paper against the heating roll lie.
The control unit 12 includes an input interface 12a that inputs temperature signals from the heaters 1lla and llb and switch 270 ON signals, as well as operation signals from the console 1 and sensor signals from various sensors in the copying machine, and a program that processes the input signals. A ROM 12b for storing, a CPU 12d for processing input signals based on a program, and an RA for temporarily storing input data, operation results, etc.
M 12 c and a control signal (including the above-mentioned drive signal) based on the calculation η of the CPU 12 d are outputted to the console 1.
It has an output interface 12 @ that controls various control objects (for example, drive motors, etc.).

In the above configuration, the operation will be explained based on the time chart of FIG.
1. However, the initial setting operations of the microcomputer are omitted).
The timer 13 is turned on for a time period Tl. This Thailand
When f13 is on and the first drive circuit 18 detects the zero cross of the power supply voltage 28, it turns on (outputs the first heater activation signal) and turns on the first triac 22 (time tz). As a result of this turning on, the first heating roll heater lla is applied with a voltage of 24 delts at time t31 and generates heat (the resistance increases to a predetermined resistance value as the temperature rises). At the same time, the delay circuit 14 turns on when the delay time T is counted from the output of the drive signal (time ta
), the second timer 15 is turned on for time T3. During this period, when the second drive circuit 19 detects the zero cross of the power supply voltage 28 (time t8), it outputs a second heater activation signal to turn on the second triac 23, and the second triac 23 is turned on. The second heater
Apply 24 volts to lb.

Second triac 2 by timeout of time T3
At the same time that T3 is turned off, the second delay circuit 16 is turned on (time ts), and when time T4 has elapsed, the third delay circuit 17 is turned on (time 11). time t
s,t? Since it coincides with the zero cross point, the third and fourth drive circuits 20, 21, and the third
, the fourth triacs 24 and 25 are turned on, and a voltage of 100 galt is applied to the first heater 11a1 and the second heater 1lb, each of which has already increased its heater resistance. When the temperature of the heating roll llc reaches a predetermined value, the output of the drive signal is interrupted, and the power supply to the first and second heaters 118.degree. 11b is cut off at time ts.

In the above description, explanations of obvious parts of the configuration and operation of the copying machine have been omitted. It's a trench, drive circuits 18, 19, 20, 21, timers 13, 15,
The operations of the delay circuits 14, 16, 17, etc. can also be replaced by microcomputer processing of the control section 12.

As explained above, according to the heater drive device for a fuser for a copying machine according to the present invention, a plurality of heaters having different power consumptions are provided, and the heaters are pre-driven at a voltage lower than a predetermined voltage in order of decreasing power consumption. By increasing the resistance and driving at a predetermined pressure, it is possible to suppress the rash current by generating noise.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention. Figure 2 is the time chart of Figure 1. Explanation of symbols l...Console, 2...Document, 3...Platen, 4...Optical system, 5...Photosensitive drum, 6...Charging section, 7...Developing section, 8 ...Transfer section, 9...Cleaner section, 10m. 10b...Paper feed tray, 11...Fixing unit, l1m. 11b...Heating roll heater, 12...Control unit,
13.15...Timer, 14,16.17...Delay circuit, 18,19,20.21...Drive circuit, 22.
23.24.25...triac, 26...transformer, 27...switch. 45

Claims (1)

[Scope of Claims] A copying machine including a drive circuit that detects a zero cross of an alternating power supply voltage and applies the alternating power supply voltage to a heating roll heater of a fixing device, wherein the heating roll heater has different power consumption. The heater is configured with a plurality of heaters, and the drive circuit pre-drives the heaters at a voltage smaller than a predetermined voltage in order of decreasing power consumption of the heaters, and then drives the heaters at a predetermined voltage. A heater drive device for a fuser for a copying machine.