JPH11174900A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the maintainability of the heating temperature of a fixing device even when power is limited and to cope with the improvement of processing speed by controlling the distribution of power supply to a heating means in accordance with the number and the kind of a driving part which is working out of driving parts actuated by the supply of power. SOLUTION: A motor and a lamp which are acting at present (that is, the number and the kind of the driving part which is working out of the driving parts driven by the supply of power) are grasped so as to estimate the rough working power of the entire device by a CPU 31. The working power at this time is compared with an upper limit value, power (allowance power) obtained by subtracting the working power from the upper limit value is converted into voltage, and a voltage value being a correction amount is impressed on a fixing heater 7 or 11. By such constitution, the power applied to the fixing heaters 7 and 11 is secured to the maximum within the limited power and a regular fixing level is secured even in the image forming device whose copying speed is high.

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, such as a copying machine or a printer, provided with a fixing device for fixing an unfixed image formed on a transfer material.

[0002]

2. Description of the Related Art Conventionally, as this type of image forming apparatus, for example, there are a copying machine, a printer, a facsimile machine and the like.

A copying machine generally has a function of reading an image of a document or the like and forms an image on a transfer material based on the read image information. There is also a copying machine having a function of inputting image information sent from a copier.

[0004] A printer is generally an external device,
For example, an image is formed on a transfer material based on image information sent from an apparatus such as a computer, and a facsimile apparatus generally has a function of reading an image of a document or the like,
Further, it has a communication function, sends read image information to the outside, and forms an image on a transfer material based on information sent from the outside.

Some of these image forming apparatuses have a fixing device for fixing an unfixed image formed on a transfer material.

The fixing device generally includes a heating roll provided with a heater inside, and a pressure roll pressed against the heating roll, and heats the transfer material while nipping and transferring the transfer material. And pressurizing to fix the unfixed image formed on the transfer material.

[0007] In such a fixing device, the quality of fixing an image to a transfer material depends on the surface temperature of the heating roll.

[0008] If the power consumption of the heating roll can be sufficiently increased, the surface temperature of the heating roll is hardly reduced even in an image forming apparatus having a high copying speed. Do not.

However, when the power used is limited (for example, 1.5 kW), the power allocated to the fixing device is limited to a certain value or less.

In the case of an image forming apparatus having a low copying speed, there is little problem in fixing an image because the surface temperature of the pressure roll is small, but in an image forming apparatus having a high copying speed,
Since the amount of heat applied to the copy paper is large relative to the heat supply power of the heating roll per unit time, the surface temperature of the heating roll tends to decrease, and as a result, there is a problem that the fixing level of the image decreases.

On the other hand, by increasing the heat capacity of the heating roll and increasing the heat storage amount of the heating roll, the surface temperature of the heating roll can be reduced even when the number of copies is large in an image forming apparatus having a relatively high copying speed. There is a method of maintaining the fixing level of an image by reducing it.

[0012]

However, even when the method of increasing the heat capacity of the heating roll and increasing the heat storage amount of the heating roll is used, it is possible to cope with the copying speed up to a certain value. Exceeding the range, the amount of heat applied to the transfer material is larger than the amount of heat stored in the heating roll + the amount of heat supplied to the heating roll, so that the level of fixing of the image is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to improve the maintainability of the heating temperature of a fixing device even with a limited electric power so that the processing speed can be improved. An object of the present invention is to provide an image forming apparatus capable of coping with the improvement of image quality.

[0014]

In order to achieve the above object, according to the present invention, an unfixed image formed on a transfer material is fixed by a fixing device having a heating unit that generates heat by supplying power. The image forming apparatus is characterized in that the distribution of power supply to the heating unit is controlled according to the number and type of operating drive units among the drive units that operate by supplying power.

Therefore, the required amount of electric power can be predicted from the number and type of operating driving units, and as much power as possible other than the required amount of electric power can be distributed to the heating means.

Further, in an image forming apparatus for fixing an unfixed image formed on a transfer material by a fixing device having a heating means for generating heat by supplying power, a measuring means for measuring power consumption is provided. It is also possible to control the distribution of power supply to the heating means based on the measurement of.

[0017] Therefore, since the power actually used other than the heating means can be measured, as much power as possible other than the measured power amount can be distributed to the heating means.

A predetermined constant power is distributed to the heating means, and the power required for the operating drive unit is subtracted from the maximum rated power of the entire apparatus. Good.

The heating means has a plurality of heating members, and the heating member preferably has a main heating member to which a predetermined constant power is distributed and a sub-heating member to which a marginal amount of power is distributed. .

A measuring means for measuring the temperature of the heating section by the fixing device may be provided, and the amount of power to be further allocated to the heating means may be determined from the marginal power based on the measurement result of the measuring means.

The amount of power to be further allocated to the heating means may be determined from the marginal power in accordance with the set number of transfer materials to be fixed.

It is preferable to provide an environment sensor for measuring the surrounding environment condition, and to determine the power to be further allocated to the heating means from the power of the margin based on the measurement result by the environment sensor.

[0023]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) A fixing device provided in an image forming apparatus according to a first embodiment of the present invention will be described with reference to FIG.

Since the basic configuration of the image forming apparatus is a well-known technique, a detailed description thereof is omitted.
This will be briefly described below.

First, an image bearing member (for example, a photosensitive member) provided in the image forming apparatus is irradiated with image light (laser light) to form an electrostatic latent image on the image bearing member.

The image can be developed (toner image) by electrostatically attaching a developer to the electrostatic latent image by a developing device.

Thereafter, the development (toner image) is transferred onto the transferred transfer material, the transfer material is transferred to a fixing device, and the unfixed image formed on the transfer material is fixed. Image formation is completed.

The embodiment of the present invention is characterized by a fixing device provided in such an image forming apparatus. Therefore, the first embodiment of the present invention will be described below with reference to FIG. The fixing device provided in the image forming apparatus according to the embodiment will be described in detail.

FIG. 1 is a schematic configuration diagram of a fixing device provided in an image forming apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the image forming apparatus is provided with a fixing device 3 for fixing an unfixed toner image 1 to a recording paper 2 as a transfer material as a permanent image by heating and pressing. I have.

A fixing roll (heating roll) 4 provided in the fixing device 3 has a hollow core 5 made of aluminum, stainless steel, or the like. A resin layer 6 having releasability is formed.

The thickness of the resin layer 6 is, for example, 20 to 100.
It can be about μm.

A heating heater 7 as a heating means is built in the cored bar 5.

The fixing roll 4 receives a driving force from a driving motor (not shown) and is rotated in the direction of the arrow in the figure.

A pressure roll 8 is rotatably pressed against the fixing roll 4, and the pressure roll 8 is driven and rotated by the fixing roll 4.

The pressure roll 8 forms a nip portion for pressing and transporting the recording paper 2 in cooperation with the fixing roll 4.

The pressure roll 8 has a hollow core 9, and an elastic layer 10 made of silicon rubber, fluorine rubber, fluorosilicone rubber or the like is formed on the outer peripheral surface of the core 9.

The thickness of the elastic layer 10 is, for example, 3 mm to
It can be about 10 mm.

A low heating heater 11 as a heating means is built in the core 9.

In this case, the heater 11 for low heating is
For example, even if the lighting state continues, a method in which the temperature of the pressure roll does not reach the control temperature of the surface of the fixing roll and the temperature is not controlled may be used, or the pressure roll may be increased by increasing the rated power, similarly to the fixing roll. Temperature control may also be performed.

Around the fixing roll 4, a temperature detecting element 12 as a measuring means for detecting the surface temperature of the fixing roll 4 is provided.
And separating claws 13 and 14 for reliably separating the fixed recording paper 2 from the fixing roll 4 or the pressure roll 8, and removing the foreign matters such as offset toner and paper powder adhered to the surface of the fixing roll 4. Cleaning means and the like for removing from the surface are arranged.

Incidentally, reference numerals 16 to 18, 20 to 29 in FIG.
And cleaning web units 16 to 18 are cleaning members for the offset toner and paper powder of the fixing roll.

Reference numerals 20 and 23 denote pressure members for pressing the web against the fixing roll to improve the cleaning ability, reference numeral 26 denotes a mandrel, and reference numerals 27 to 29 denote members forming the surface layer. Yes, for example, an elastic layer.

Reference numerals 21 and 22 denote cylindrical members (rotating members) for forming a web transport path, and reference numerals 24 and 25 denote pressurizing members for preventing the web from sagging.

The heaters 7 and 11 installed in the fixing roll and the pressure roll are supplied from the power source 33 to the power control circuit 3.
2, power is supplied through the CPU 2 and ON / OFF of the applied voltage and the applied voltage are determined by a signal from the CPU 31.

For example, as an example, heaters 7 and 11
Of the reference power of 90V / 750W and 90V / 7
0W.

First, since the power used by the heater other than the heater is very small at the time of startup (because the motor and the image exposure lamp are not operating), the voltage applied to the heater 7 at startup is 100 V, for example, Is set to, for example, 105V.

In this way, the temperature of the pressure roll is increased faster, so that the amount of heat of the entire fixing device when the image forming apparatus itself is started up is larger than that when the reference power is used.

When a copying operation is performed thereafter, a reference value of 90 V is first applied to the heaters 7 and 11.

Next, the CPU 31 can grasp the motors, lamps, and the like that are currently operating (ie, the number and type of the operating drive units among the drive units that are driven by power supply). The power can be estimated.

At this time, the used electric power is compared with an upper limit value (for example, 1.5 kW as a maximum rated electric power value), and the electric power obtained by subtracting the used electric power from the upper limit value (an electric power for a margin) is converted into a voltage to obtain a heater. A voltage value for correction (for example, 95 V) is applied to 7 or 11.

With the above configuration, it is possible to secure the maximum power to the fixing heater among the limited power.
It has become possible to secure a fixed fixing level even for an image forming apparatus having a high copying speed.

Such control is particularly effective in continuous multi-sheet copying requiring a large amount of heat in the fixing device.

In the above description, a configuration has been described in which the approximate power consumption of the entire apparatus is estimated from the number and type of operating drive units, and a marginal power is obtained based on the estimated value. If a power meter as a measuring unit is installed in the image forming apparatus itself, it is possible to obtain a marginal power based on the actually measured value, so that it is possible to perform finer power control.

In the above description, the case where both the fixing roll and the pressure roll have heating means has been described.
Even when only the fixing roll has a heating unit, the same effect as in the above case can be obtained by allocating the correction amount in the same manner.

Further, in the above description, when supplying the additional power, the same voltage is applied by increasing the applied voltage of the same heater as that for supplying the reference voltage. A heater (auxiliary heating member) different from the heater (main heating member) for power up may be separately provided, and when the additional power is supplied, the heater for power up may be turned on.

(Second Embodiment) In this embodiment, control is performed to determine whether or not to supply an additional amount of electric power, or to determine the amount of electric power to be supplied, according to the use state of the apparatus. Configuration.

Since the basic configuration and the like are the same as those described with reference to FIG. 1 in the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted. The description will be omitted, and the control that is a feature of the present embodiment will be described in detail below.

In the present embodiment, during the image forming (copying) operation, when the power value of the difference between the upper limit value of the power (for example, 1.5 kW) and the used power is distributed to the fixing device, The distribution of power is switched according to the operation status.

First, when the image forming (copying) operation is performed, the value of the surface temperature of the fixing roll is measured at regular time intervals.

At this time, the surface temperature of the fixing roll is compared with the control temperature of the fixing roll, and the difference is determined to be a certain value or more (for example, 5
° or more), or when the temperature of the fixing roll decreases rapidly within a certain period of time, it is considered that the calorific value of the fixing roll is considerably insufficient.

Therefore, in the case of the present embodiment, the power of the difference between the maximum rated power value and the used power value is supplied to the fixing roll heater so as to suppress a decrease in the temperature of the fixing roll in order to maintain the fixing property of the image. In addition, if the temperature is supplied preferentially or only to the fixing heater, a decrease in the temperature of the fixing roll is suppressed,
The fixing level can be maintained.

If the difference between the surface temperature and the control temperature is less than or equal to a certain value when the surface temperature of the fixing roll is observed at regular time intervals, it is determined that the amount of heat of the fixing roll is sufficient. Either the difference power from the upper limit is supplied to the heater of the pressure roll, or the difference power is not supplied.

By doing this, if the amount of heat is extremely insufficient when the fixing device is used, the power of the difference from the upper limit value is preferentially supplied to the fixing roll, so that the copying speed can be reduced. The fixing level can be maintained even for a fast image forming apparatus.

Further, if the number of copies set at this time is also included in the judgment conditions, fine control becomes possible.

For example, when it is determined that the set number of sheets is small (when the number of sheets is set to a certain value or less), it is possible to judge that the temperature of the fixing roll decreases little. Therefore, a difference from the upper limit power value is added to the fixing device. Don't do that.

In this case, the fixing level can be maintained.

However, when the set number is large, it can be determined that the temperature of the fixing roll is greatly reduced. Therefore, immediately after the start of the copying operation, the power of the difference between the upper limit power value and the used power is prioritized. By supplying the heater to the heater, a decrease in the temperature of the fixing roll is reduced, and the fixing level can be maintained.

For example, when the normal power consumption of the fixing device is 75
0 W, at a process speed of about 380 mm / s,
When copying a large number of sheets (for example, 400 to 500 sheets) using an image forming apparatus having a copy capacity of 60 sheets / minute, when the set number of copies is 100 or more, the difference from the upper limit power value (for example, about 80 W) When the control condition that the fixing roller is supplied to the fixing roll heater from the start of copying is set, the fixing level is maintained because the surface temperature of the fixing roll differs by about 10 ° C. as compared with the case where no difference is applied to the fixing roll as shown in FIG. It is possible to do.

This is an example, and is an amount that can change if the heat capacity of the fixing device or the control temperature of the fixing roll changes.

In the above description, the environment in which the image forming apparatus is placed is not particularly described. However, if the condition for adding the difference power by the environment sensor is changed (for example, when the temperature is low or when the humidity is high, the difference is not changed). The timing for applying the power is advanced.) More detailed measures can be taken.

The additional power can be divided into several stages according to the temperature difference between the surface temperature of the fixing roll and the control temperature of the fixing roll, the set number of sheets, and the like.

As described above, it is possible to cope with the use state and use environment state of the apparatus.

[0075]

As described above, according to the present invention, the distribution of power supply to the heating means is controlled in accordance with the number and type of operating drive units among the drive units which operate by supplying power. Therefore, depending on the number and type of operating drive units,
The amount of power required for these can be predicted, and as much power as possible other than the required amount of power can be distributed to the heating means, so that the heating temperature of the fixing device can be appropriately maintained even with limited power. Thus, the processing speed can be improved.

Further, by providing a measuring means for measuring the used electric power and controlling the distribution of the electric power supply to the heating means based on the measurement of the measuring means, it is possible to control the distribution more finely. .

Based on the measurement result of the measuring unit for measuring the temperature of the heating unit by the fixing device, the set number of transfer materials to be fixed, or the measurement result of the environment sensor for measuring the surrounding environment, the heating unit is further supplied to the heating unit. If the amount of electric power to be distributed is determined, it is possible to cope with the use situation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device provided in an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a relationship between the number of copies and a fixing roll surface temperature;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unfixed toner image 2 Recording paper 3 Fixing device 4 Fixing roll 7, 11 Heater 8 Pressure roll 31 CPU 32 Power control circuit 33 Power supply

Claims (7)

[Claims] In an image forming apparatus for fixing an unfixed image formed on a transfer material by a fixing device having a heating unit that generates heat by supplying power, a driving unit that operates by supplying power is operated. An image forming apparatus, wherein the distribution of power supply to the heating unit is controlled according to the number and type of driving units in the image forming apparatus. 2. An image forming apparatus for fixing an unfixed image formed on a transfer material by a fixing device having a heating unit that generates heat by supplying power, wherein a measuring unit for measuring power consumption is provided. An image forming apparatus configured to control distribution of power supply to the heating unit based on the measurement of the image forming apparatus. 3. A predetermined constant power is distributed to the heating means, and the power required for the operating drive unit is subtracted from the maximum rated power of the entire apparatus. The image forming apparatus according to claim 1, wherein: 4. The heating means has a plurality of heating members, and the heating member has a main heating member to which a predetermined constant power is distributed and a sub-heating member to which a marginal power is distributed. The image forming apparatus according to claim 3, wherein: 5. A measuring device for measuring a temperature of a heating section by a fixing device, wherein an amount of power to be further allocated to the heating device is determined from the marginal power based on a measurement result of the measuring device. The image forming apparatus according to claim 3, wherein: 6. The image according to claim 3, wherein the amount of power to be further allocated to the heating means is determined from the marginal power in accordance with the set number of used transfer materials to be fixed. Forming equipment. 7. An apparatus according to claim 1, further comprising an environment sensor for measuring a surrounding environment condition, wherein the power to be further allocated to the heating means is determined based on the surplus power based on the measurement result of the environment sensor. 7. The image forming apparatus according to any one of 3 to 6.