JP2003173108A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the voltage fluctuation (flicker) of a power source caused when a heater is turned on and off during successive copying and also to perform an optimum temperature control to the flicker in accordance with the kind of transfer paper and environmental temperature. <P>SOLUTION: This image forming apparatus is provided with several heaters to heat a fixing roller, a means to individually turn on/off the several heaters and a controlling means to change the temperature control range individually set in accordance with the individual temperature control range set so that temperature control is individually performed for every heater by individually turning on/off, the material of the transfer paper and the environmental temperature, so that fixing temperature control corresponding to the kind of the transfer paper and the environmental temperature is performed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for thermally fixing a toner image formed on a transfer paper with a fixing roller or a belt to form an image.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for forming an image by thermally fixing a toner image formed on a transfer sheet with a fixing roller stably fixes the toner image. I have to keep it. Further, in recent years, power consumption regulations such as Energy Star and the Energy Conservation Law have become stricter, and demands for reduction of power consumption by users have also increased. Therefore, instead of the control that keeps the heater turned on, the temperature control is performed by turning the power on and off finely with respect to the temperature change to reduce the power consumption and reduce the temperature change.

[0003]

However, if such a fine on / off operation is repeated, EN61000-3-
There is a drawback that the value of the voltage fluctuation (flicker) regulated in 3 becomes worse. Further, in the method of detecting and feeding back the temperature of the fixing roller and controlling the temperature, the number of times of ON / OFF and the duty change depending on the difference in material such as plain paper and thin paper and the environmental temperature.

[0004]

In view of the above problems, in the present invention, the toner image formed on the transfer material is heated by the heating means to fix the image and the heating and pressurizing means. At least one provided for
One or more heaters, a plurality of heaters independent on / off means for independently turning on / off the plurality of heaters, and a plurality of heaters independent on / off means for controlling each heater within an individual temperature control temperature range set for each heater. In an image forming apparatus having independent temperature control means for controlling temperature, temperature control temperature range control means for changing the individual temperature control temperature range according to the type of transfer material by the independent temperature control means, formed on the transfer material The fixed toner image is fixed by heating the formed toner image by the heating unit, at least one heater provided for heating the heating and pressurizing unit, and the plurality of heaters are independently turned on and off. By means of the plural heater independent on / off means and the plural heater independent on / off means, each heater is controlled within the individual temperature control temperature range set for each heater. In an image forming apparatus having an independent temperature adjusting unit for adjusting temperature, a temperature adjusting temperature range control unit for changing the individual temperature adjusting temperature range according to the ambient environment temperature by the independent temperature adjusting unit, is formed on the transfer material. The toner image is heated by the heating means to fix the image, the at least one heater provided to heat the heating and pressurizing means, and a plurality of heaters for independently turning on and off the plurality of heaters. In the image forming apparatus, the heater independent on / off means and the independent temperature control means for controlling the temperature of each heater within the individual temperature control temperature range set for each heater by the plurality of heater independent on / off means are provided. By providing a temperature control temperature range control means for changing the individual temperature control temperature range according to the ambient environment temperature and the type of transfer material by the temperature control means, It is obtained by solving the point.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional structural view for explaining an example of an image forming apparatus of the present invention. 100 is a copying apparatus main body, 142 is a circulating automatic document feeder (hereinafter referred to as RD) for automatically feeding originals.
When a plurality of originals are piled upward, the originals are read in order from the bottom one.

The operation of the image forming apparatus of this embodiment will be described below.

In FIG. 1, reference numeral 101 is a document table glass as a document placing table, and 102 is a document illumination lamp which constitutes a scanner together with a scanning mirror 103. The scanner is reciprocally scanned in a predetermined direction by a motor (not shown), and the reflected light of the document is passed through the scanning mirrors 103 to 105 to the lens 10
After passing through 7, the image is formed on the CCD sensor 108.

Reference numeral 117 denotes a laser, which is an image sensor unit 10.
The photosensitive drum 110 is irradiated with a laser beam that is converted into an electric signal in 6 and modulated based on the image signal that has been subjected to predetermined image processing in the image controller 139.

Around the photosensitive drum 110, a primary charging device 113, a developing device 118, a transfer charging device 127, a separation charging device 128, a cleaning device 111, and a pre-exposure lamp 112.
Is equipped with. In the image forming unit 126, the photoconductor drum 110 is rotated in the direction of the arrow shown in the figure by a motor (not shown), and after being charged to a desired potential by the primary charger 113, the image from the image control unit 139. Laser light is emitted from the laser 117 according to the data, and an electrostatic latent image is formed. The electrostatic latent image formed on the photoconductor drum 110 is developed by the developing device 118 and visualized as a toner image. On the other hand, the pickup rollers 123, 12 from the upper cassette 122 or the lower cassette 124
The transfer paper fed by the No. 4 feeds the feed rollers 138, 13
9 is sent to the main body and is fed to the transfer belt by the resist roller 126, and the visualized toner image is transferred to the transfer paper by the transfer charger 127. After the transfer, the cleaning device 111 cleans the residual toner on the photosensitive drum, and the pre-exposure lamp 112 erases the residual charge.

After the transfer, the transfer paper is sent to the fixing device 130 by the conveyor belt 129. The fixing period device 130 is 2 above and below
Two heaters, a main heater 132 and a sub-heater 133, are inserted inside the upper roller, and a heater control unit (not shown) is output by the output of a thermistor 134 pressed against the surface of the upper roller. Thus, the main heater 132 and the sub heater 133 are controlled to be turned on / off to keep the temperature of the roller surface constant.
It is fixed by pressure and heat in the fixing device 130, and is discharged to the outside of the main body by the discharge roller 131.

A temperature / humidity sensor 150 detects the environmental temperature and humidity in which the copying machine is placed.

Next, the heater control of this embodiment will be described with reference to the block diagram of the heater control section shown in FIG.

In FIG. 2, 201 is a CPU, 202, 2
Reference numeral 03 is a heater control triac, 204 is a main heater, 205 is a sub heater, 206 is a temperature detecting thermistor, 207 is a voltage dividing resistor, and 208 is a commercial power source (1
00V). Here, the CPU 201 detects the temperature of the fixing roller based on the divided voltage of the temperature detecting thermistor 206 and the resistor 207, and controls the operations of the triacs 202 and 203 to control the lighting of the main heater 204 and the sub-heater 205 to fix the fixing roller. The roller temperature is kept constant.

Next, the relationship between the temperature change of the conventional fixing device and the on / off of the main heater and the sub heater will be described with reference to FIG.
Starting from FIG. 3 to 8 show the difference in the number of times of ON / OFF according to the conventional temperature control method.

FIG. 3 is a continuous copy of plain paper in a low temperature environment, FIG. 4 is a continuous copy of thin paper in a low temperature environment, FIG. 5 is a continuous copy of plain paper in a normal temperature environment, and FIG. 6 is a continuous copy of thin paper in a normal temperature environment. 7 shows a continuous copy of plain paper in a high temperature environment, and FIG. 8 shows a continuous copy of thin paper in a high temperature environment.

In FIGS. 3 to 8, a temperature control range ΔTa and a temperature control range ΔTb are set for the temperature control center temperature Tc. In this embodiment, the temperature adjustment range ΔTa is adjusted by the sub heater, and the temperature adjustment range ΔTb is adjusted by the main heater. For example, if the temperature control center is 200 ° C., the temperature control range ΔTa is 198 ° C. to 202 ° C., and the temperature control range ΔTb is
Is set to 195 ° C to 205 ° C.

FIG. 3 shows a case where continuous copying of plain paper is performed in a low temperature environment. The main heater and sub heater are fully lit. In this case, the amount of heat taken by the transfer paper is balanced by fully turning on the main heater and the sub-heater, so the temperature of the fixing device is within the temperature control range ΔTa. Even if the fixing roller is deprived of heat by the transfer paper, if the fixing roller can be warmed by the amount of heat deprived between the papers, temperature control as shown in FIG. 3 is possible.

However, even if the same control as in FIG. 3 is performed, when the transfer paper has a small heat capacity such as thin paper, the amount of heat absorbed by the transfer paper is smaller than that in FIG. The temperature of the fixing roller gradually rises, and reaches the upper limit Tau of the temperature control range ΔTa at t1. When the upper limit of the temperature control range ΔTa is reached, the sub heater is turned off. If continuous copying is performed with the sub-heater turned off, the temperature of the main heater will fall, and the temperature will not be enough. When the temperature control temperature reaches the lower limit Tal of the temperature control range ΔTa at t2, the sub heater is turned on again and the temperature starts rising. As described above, even if the temperature control method is the same, the number of times the heater is turned on and off varies depending on the transfer paper. The larger the number of times of on / off, the more disadvantageous to flicker.

Next, FIG. 5 shows the case where the plain paper transfer paper is the same as that of FIG. 3 but the ambient temperature is normal temperature. In a normal temperature environment, when the heater is turned on, the amount of heat taken by the transfer paper is small, so the temperature rises rapidly during continuous copying. When both the main heater and the sub-heater are in the ON state, the amount of heat accumulated is larger than the amount of heat absorbed by the transfer paper, so the temperature rises sharply. When the temperature reaches the upper limit Tau, the sub heater is turned off, and the on / off operation as shown in FIG. 5 is performed.

Next, when the transfer paper becomes thin from the state of continuous copying at room temperature plain paper in FIG. 5, the heat capacity taken by the transfer paper is small, and the result is as shown in FIG. Even if the sub-heater is turned off at t3, the temperature drop is slower than in FIG. 5 because the transfer paper takes less heat. 7 and 8 show cases of plain paper and thin paper in a high temperature environment.

The heat capacity of the fixing roller and the heat capacity of the transfer paper have been described above with reference to FIGS. 3 to 8.
These are determined by the relationship between the heat quantity of the heater heating the fixing roller, the heat capacity of the fixing roller, and the heat capacity of the transfer paper.

FIGS. 3 to 8 show the difference in the number of times of turning on and off according to the conventional temperature control method.

In the description with reference to FIGS. 3 to 8, the temperature control range ΔTa and the temperature control range ΔTb are fixed values and the temperature control range Δ is constant.
The relationship of Ta <temperature control range ΔTb is always maintained.
As described above, in the conventional example, the temperature control range and its value are fixed from the viewpoint of ease of control.

However, in this embodiment, the temperature control range is changed as shown in FIGS. For example, FIG. 9 is a diagram showing the heater on / off timing and the fixing device temperature when the temperature control range ΔTa in the case of FIG. 4 is widened. By increasing the temperature control range ΔTa, the number of times the sub heater is turned on and off is reduced. 11 and 12 show the temperature control temperature range Δ
The range of Ta and ΔTb is reversed.

As a result, in terms of control, on / off control is performed in which the sub-heater remains on and the main heater occasionally turns on. In contrast to FIG. 11, in FIG. 12, the temperature control range ΔTb is further changed. By changing or combining the temperature control ranges in this way, it is possible to reduce the number of times the heater is turned on and off.

Next, parameters for changing the temperature control range of this embodiment will be described.

Here, the input of the transfer paper material when the temperature control range is changed using the material of the transfer paper as a parameter will be described.

FIG. 13 shows an operation panel display of the image forming apparatus of this embodiment.

In the operation panel display of FIG. 13, 1301 is a copy start key, 1302 is a stop key, and 1303 is a liquid crystal touch panel display section.

Here, a case where the liquid crystal touch panel unit 1303 is a paper type registration screen will be described. This screen is a screen for registering the type of paper in the paper cassette or deck in advance in the machine. Plain paper, recycled paper, and colored paper are selected by touching 1306, 1307, and 1308. Even if recycled paper or colored paper is selected, the temperature control of the fixing heater does not change because it is plain paper.

It is 1309 or 1 to select thick paper or thin paper.
310 touch keys. When thin paper is selected in the low temperature environment, the temperature control range shown in FIG. 4 is changed to the temperature control range shown in FIG.

In the normal temperature environment, control is performed in the temperature control range shown in FIG. 10 for plain paper, and temperature control shown in FIG. 6 is performed when thin paper is selected.

In the case of a high temperature environment, the temperature is controlled in the temperature control range of FIG. 11 for plain paper, and in the temperature control range of FIG. 12 for thin paper.

FIG. 14 shows a flowchart of this embodiment. At 1402, the main body of the copying machine detects the environmental temperature in which the apparatus is placed in advance. Subsequently, at 1403, it is determined whether the transfer paper in the cassette is registered as thin paper or plain paper. When copying is started in 1404, the temperature control temperature range for standby is changed to a temperature control temperature range according to the type of transfer paper (1405).

After that, a copy job (1406) is performed, and when the copy job ends normally at 1407, 14
At 08, the temperature control range is returned to the standby mode, and the processing for changing the temperature control temperature range during copying according to the type of transfer paper is completed.

The above is the description of the first embodiment.

(Embodiment 2) Next, a second embodiment will be described. In the first embodiment, the type of transfer paper is set by inputting from the liquid crystal touch panel, but in the third embodiment, a method of automatically detecting whether the transfer paper is plain paper or thin paper will be described.

As shown in FIG. 15, the roller 15 of the paper feeding unit
A displacement sensor 1501 is provided to detect how much the roller 1502 is displaced depending on the thickness of the transfer paper when the transfer paper is sandwiched between 02 and 1503. Roller 150
When the transfer paper is conveyed by 2 and 1503, the CPU 201 shown in FIG. 2 determines the type of the transfer paper based on the paper thickness information detected by the displacement sensor, and changes the fixing temperature control range.

FIG. 17 is a flowchart of the second embodiment. In the second embodiment, the material of the transfer paper is not registered in advance, but is automatically detected during copying. Therefore, after the copy key is pressed, plain paper thin paper discrimination is performed (170).
4).

(Third Embodiment) Next, a third embodiment will be described with reference to FIG. In the first and second embodiments, the CPU 201
Although the configuration for realizing the control of the present invention by the arithmetic processing according to the above is described, the configuration for realizing the control of the present invention by the hardware circuit without using the CPU will be described in the third embodiment.

In FIG. 16, 134 is a thermistor for detecting the temperature of the fixing roller, 150 is an environmental temperature sensor for detecting the environmental temperature of the copying machine, and 1501 is the paper thickness sensor described in the second embodiment. Here, the thermistor 134 has a characteristic that the resistance value decreases as the temperature rises. Comparator-1 based on the temperature of the thermistor 134
Reference numerals 617 and 1619 generate ON / OFF signals for the main heater and the sub heater, respectively.

Hysteresis characteristics are provided in the comparators 1617 and 1619. As shown in FIG. 18, when the input of the comparator minus terminal exceeds V1, the output is inverted, and when it is V2 or less, the output is inverted again. The values of V1 and V2 are determined by the feedback resistor R10 connected to the plus terminal of the comparator, R7, R8, R11, and the power supply 1618.

When the negative input terminal voltage of the comparator 1617 is Vi, the output voltage is Vo, and the voltage of the power supply 1618 is VR, V1 in FIG. 18 is V1 = R10 × VR / (R10 + R7 + R8 + R11)
+ (R7 + R8 + R11) × Vo / (R10 + R7 + R
8 + R11), and V2 is V2 = R10 × VR / (R10 + R7 + R8 + R11)
− (R7 + R8 + R11) × Vo / (R10 + R7 + R
8 + R11)

Next, the output from the environmental temperature sensor will be described. Here, it is assumed that the output from the environmental temperature sensor 150 is a voltage output, the higher the environmental temperature, the higher the output voltage, and the lower the environmental temperature, the lower the output voltage.

The output from the ambient temperature sensor 150 is compared with a reference voltage by two comparators 1601 and 1602. In the case of a low temperature environment, both the comparators 1601 and 1602 output a low level. In a room temperature environment, the comparator 1601 outputs a low level and 1602 outputs a high level. In a high temperature environment, both the comparators 1601 and 1602 output a high level.

Next, the paper thickness sensor will be described. Here, for the sake of convenience, the output from the paper thickness sensor 1501 is such that the thinner the paper, the lower the voltage, and the thicker the paper, the higher the voltage.

The output of the paper thickness sensor is the comparator 161.
By comparing in 1, it is determined whether the paper is plain paper or thin paper. Here, the threshold level is set between plain paper and thin paper. Therefore, the comparator 1611 outputs a high level when the paper is thicker than plain paper, and outputs a low level when the paper is thin.

The value of the + terminal ground resistance of the hysteresis comparator is changed by the combination of the output of the environmental temperature sensor and the output of the paper thickness sensor.

For example, in the case of high-temperature environment thin paper continuous copying, the output of the comparator 1601 is high and the output of the comparator 1611 is low. Since the output of the inverter 1603 is low, the transistor 1609 is off and R1
An electric current flows through 2. Since the output of the inverter 1622 is low, both AND gates 1612 and 1613 output low. The OR gate 1616 also has a low output, and the inverter 1615 has a high output.
610 turns on, and both ends of R13 are short-circuited.

On the other hand, point a is low, point b is high, transistor 1607 is off, transistor 1608 is on, and R8 is short-circuited.

Thus, the value of the + terminal ground resistance of the hysteresis comparator is selected by the combination of the output of the environmental temperature sensor 150 and the output of the paper thickness sensor 1501. The hysteresis width of the hysteresis comparator is changed by changing the + terminal ground resistance value of the hysteresis comparator. That is, the temperature control temperature range is changed.

The above is the description of the third embodiment.

[0054]

According to the present invention, it is possible to optimize the number of times the fixing heater is turned on and off with respect to the type of transfer material and various environmental temperatures during copying. ) Can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus.

FIG. 2 is a block diagram of the present invention.

FIG. 3 shows a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb by a main heater, and a temperature control range ΔTa by a sub heater during continuous copying of plain paper in a conventional low temperature environment. It is the figure shown.

FIG. 4 shows a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb by a main heater, and a temperature control range ΔTa by a sub heater during continuous copying of thin paper in a conventional low temperature environment. It is a figure.

FIG. 5 shows a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb by a main heater, and a temperature control range ΔTa by a sub heater when continuously copying plain paper in a conventional room temperature environment. It is the figure shown.

FIG. 6 shows a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb by a main heater, and a temperature control range ΔTa by a sub heater during continuous copying of thin paper in a conventional room temperature environment. It is a figure.

FIG. 7 shows a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb by a main heater, and a temperature control range ΔTa by a sub heater during continuous copying of plain paper in a conventional high temperature environment. It is the figure shown.

FIG. 8 shows a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb by a main heater, and a temperature control range ΔTa by a sub heater during continuous copying of thin paper in a conventional high temperature environment. It is a figure.

FIG. 9 is a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb ′ by a main heater, and a sub heater when continuously copying thin paper in a low temperature environment when the present invention is implemented. It is a figure showing temperature control range delta Ta '.

FIG. 10 is a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb ′ by a main heater, and a sub heater during continuous copying of plain paper in a normal temperature environment when the present invention is implemented. 6 is a diagram showing a temperature control range ΔTa ′ according to FIG.

FIG. 11 is a main heater ON / OFF signal, a sub heater ON / OFF signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb ″ by a main heater, and a sub heater during continuous copying of plain paper in a high temperature environment when the present invention is implemented. It is the figure which showed the temperature control range (DELTA) Ta '' by a heater.

FIG. 12 is a main heater on / off signal, a sub heater on / off signal and a fixing roller temperature detection signal by a thermistor, a temperature control range ΔTb ″ by a main heater, a sub heater when continuously copying thin paper in a high temperature environment when the present invention is implemented. 6 is a diagram showing a temperature control range ΔTa ″ according to FIG.

FIG. 13 is an operation panel display of the image forming apparatus of the present invention,
FIG. 9 is an explanatory diagram of a screen for registering the type of transfer paper.

FIG. 14 is a flowchart of the first embodiment.

FIG. 15 is a diagram showing a method for automatically determining the type of transfer paper according to the second embodiment of the present invention.

FIG. 16 is a circuit diagram of Embodiment 3 of the present invention.

FIG. 17 is a flowchart of a second embodiment.

FIG. 18 is an explanatory diagram showing the input / output relationship of the hysteresis comparator of the third embodiment.

[Explanation of symbols]

201 CPU 204 Main heater 205 Sub heater 206 thermistor

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 DA11 DC02 DE04 DE07 EA12                       EC06 EC20                 2H033 AA32 AA47 BA25 BA30 BA59                       BB18 BB28 CA07 CA08 CA16                       CA27 CA45                 3K058 AA46 BA18 CA12 CA22 CA61                       CB02 DA01 GA06

Claims (3)

[Claims] 1. A toner image formed on a transfer material is heated by a heating unit to fix the image, and at least one unit is provided for heating the heating and pressing unit.
One or more heaters, a plurality of heaters independent on / off means for independently turning on / off the plurality of heaters, and a plurality of heaters independent on / off means for controlling each heater within an individual temperature control temperature range set for each heater. An image forming apparatus having an independent temperature adjusting unit for adjusting the temperature, characterized in that the independent temperature adjusting unit has a temperature adjusting temperature range control unit for changing the individual temperature adjusting temperature range according to the type of the transfer material. Image forming apparatus. 2. A toner image formed on a transfer material is heated by a heating unit to fix the image, and at least one unit is provided for heating the heating and pressing unit.
One or more heaters, a plurality of heaters independent on / off means for independently turning on / off the plurality of heaters, and a plurality of heaters independent on / off means for controlling each heater within an individual temperature control temperature range set for each heater. An image forming apparatus having independent temperature adjusting means for adjusting temperature, characterized in that the independent temperature adjusting means has temperature adjusting temperature range control means for changing the individual temperature adjusting temperature range in accordance with the ambient environment temperature. Image forming apparatus. 3. A toner image formed on a transfer material is heated by a heating means to fix an image, and at least one is provided for heating the heating and pressing means.
One or more heaters, a plurality of heaters independent on / off means for independently turning on / off the plurality of heaters, and a plurality of heaters independent on / off means for controlling each heater within an individual temperature control temperature range set for each heater. An image forming apparatus having independent temperature adjusting means for adjusting temperature, further comprising temperature adjusting temperature range control means for changing the individual temperature adjusting temperature range by the independent temperature adjusting means according to the ambient environment temperature and the type of transfer material. An image forming apparatus characterized by the above.