JP2002318504A - Image forming device - Google Patents

Abstract

(57) Abstract: The present invention provides an image forming apparatus that efficiently and accurately controls a fixing heater of a fixing unit that fixes a toner image on transfer paper to a target temperature. A fixing unit includes a fixing roller and a pressure roller. Two heaters connected in series to a power supply circuit are housed in the fixing roller. A switch 35 is connected in parallel with the heater 33, and a first mode in which only the heater 32 is energized when the switch 35 is turned on / off, and a second mode in which the heater 32 and the heater 33 are energized. The mode is switched to the mode, and the fixing roller 17 is heated. Therefore, the fixing roller 17 is quickly heated in the first mode at the time of startup or the like, and the fixing roller 17 is stably and accurately controlled to the fixing temperature in the second mode during image formation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that efficiently and accurately controls a fixing heater of a fixing section for fixing a toner image onto transfer paper to a target temperature.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, and a facsimile machine, an electrostatic latent image is formed on a photosensitive member by light modulated based on image information, and the electrostatic latent image is formed. The toner is adhered to the photoreceptor and developed. The toner attached to the photoreceptor is transferred to a transfer sheet, and the transfer sheet with the toner is applied to a pressure contact portion between a fixing roller of a fixing unit heated by a fixing heater and a pressure roller pressed against the fixing roller. The transfer paper is conveyed, and the transfer paper is heated and pressed by a fixing roller and a pressure roller to fix the toner on the transfer paper.

[0003] In this fixing apparatus, a heating method using a halogen heater as a heat source has been widely used as a fixing heater. In order to control the temperature of the fixing roller heated by the fixing heater, the fixing roller is heated. A temperature control element represented by a thermistor is brought into contact with a protective film such as polyimide. Then, the image forming apparatus supplies power to the halogen heater by an AC power supply circuit including a safety device such as an AC power supply, a triac, and a temperature fuse, and an electric wire connecting them, and heats the fixing roller to a predetermined fixing temperature. I have.

A CP that controls this AC power supply circuit
U (Central Processing Unit) controls the fixing roller to a preset temperature by outputting a signal for controlling energization of the halogen heater to the triac based on the temperature detected by the thermistor and driving the triac. In addition, the safety device is inserted in series with the AC power supply circuit and is disposed close to the surface of the fixing roller. When the surface temperature of the fixing roller exceeds a predetermined limit temperature, the safety device is not connected to the safety device. Cut off the power supply to the heater.

As described above, the fixing section of the image forming apparatus nips and conveys the transfer paper on which the toner has been transferred between the rotating fixing roller and the pressing roller while rotating the heated fixing roller. The toner is heated and melted to fuse the toner onto the transfer paper. However, due to recent environmental regulations and increasing awareness of environmental protection, various image forming apparatuses require a heating element (fixing heater) of a fixing unit when not in use. A so-called energy saving control is performed in which power supply to the power supply is cut off and power is supplied only when necessary to reduce power consumption.

In such an energy saving type image forming apparatus,
During printing, the surface temperature of the fixing roller needs to quickly reach the set temperature. To satisfy this requirement, attempts have been made to reduce the heat capacity of the fixing roller.

[0007]

However, in such a conventional image forming apparatus, when the power is turned on or when the mode is changed from the energy saving mode to the printing mode, the surface temperature of the fixing roller is quickly increased to the set temperature. To reduce the heat capacity of the fixing roller, the heat capacity of the fixing roller is reduced. However, the reduction of the heat capacity of the fixing roller alone has been limited, although the thickness of the core of the fixing roller has been reduced. In addition, although the temperature of the fixing roller is raised quickly by reducing the heat capacity of the heating source, there is a problem that improving the efficiency of the heating source leads to shortening the life of the heating source.

Therefore, the present invention is directed to a fixing roller heated by a heating source and a rotating roller together with the fixing roller in contact with the fixing roller to transfer the toner image-transferred paper to the fixing roller and the pressure roller. As a heating source for heating a fixing roller of a fixing unit for fixing the toner image to the transfer paper while conveying while heating and pressurizing the toner image, at least a main heating source and an auxiliary heating source connected in series to a power supply circuit are provided. The switching means is connected in parallel with the auxiliary heating source to perform on / off operation, and when turned on, directly connects the main heating source to the power supply circuit to supply power from the power supply circuit only to the main heating source. By switching between the first mode and the second mode in which the main heating source and the auxiliary heating source are supplied with power from the power supply circuit when the mode is off, an image such as at startup and during image forming operation can be obtained. The output of the heating source is appropriately and inexpensively switched according to the state of the forming apparatus, the fixing roller is quickly heated to a predetermined temperature, and the heating source is used while suppressing the output during the minimum image forming operation. It is an object of the present invention to provide an image forming apparatus that can have a long life.

According to a second aspect of the present invention, when the fixing roller needs to be rapidly heated when the power is turned on or when returning from the standby state, the fixing roller is heated in the first mode. When the fixing roller is heated to a predetermined fixing temperature, the fixing roller is heated in the second mode. The object of the present invention is to provide an image forming apparatus that supplies power at a rated output during image forming operation, shortens a rise time, reduces power consumption by efficiently using power, and extends the life of a heating source. And

According to a third aspect of the present invention, when rapid heating of the fixing roller is required, for example, when the power is turned on or when returning from the standby state, the fixing roller is heated in the first mode, and the fixing roller is heated. When the fixing roller is heated to a predetermined fixing temperature, the first mode and the second mode are appropriately selected and the fixing roller is heated based on the detection result of the detection sensor for detecting the temperature of the fixing roller. When the temperature at the edge of the fixing roller is low or when the temperature at the edge of the fixing roller rises when passing small-size transfer paper, make appropriate heat distribution adjustments to make the temperature distribution of the fixing roller uniform. It is another object of the present invention to provide an image forming apparatus that performs more appropriate fixing.

According to a fourth aspect of the present invention, the power supply circuit is provided with a function of controlling the power supply to the main heating source and the auxiliary heating source in a phase control or pulse-like manner, and the first mode and the second mode are appropriately selected. When the pressure roller is heated, the power supply circuit controls the phase or the pulse to control the average power in the first mode to be substantially the same as the power in the second mode, so that an image can be formed during the image forming operation. Depending on the state of the forming apparatus, the main heating source alone or the main heating source and auxiliary heating source can be switched in series as appropriate, and efficient power can be used to achieve more appropriate fixing and reduce power consumption. It is another object of the present invention to provide an image forming apparatus in which a heating source has a long life.

According to a fifth aspect of the present invention, the average power when the fixing roller is heated by appropriately selecting the first mode and the second mode for the main heating source and the auxiliary heating source is H1, and the consumption in the first mode is H1. The power is H2, the power consumption in the second mode is H3,
The power consumption other than the power consumption of the fixing unit in the standby state of the image forming apparatus is A1, the power consumption other than the power consumption of the fixing unit during the image forming operation of the image forming apparatus is A2, and the rated power of the image forming apparatus is M. When H3 ≦ M−A2 and H1 ≦ M−A2, the power that satisfies H2 ≦ M−A1 is consumed, so that the rated power of the image forming apparatus depends on the state of the image forming apparatus. As the heating source, the main heating source alone and the main heating source and the auxiliary heating source are switched in series as appropriate, and the configuration of the main heating source and the auxiliary heating source is set so that the power consumption at this time is constant, It is an object of the present invention to provide an image forming apparatus that performs more appropriate fixing and uses power efficiently to reduce power consumption.

According to a sixth aspect of the present invention, the main heating source and the auxiliary heating source have different heat distributions in the axial direction of the fixing roller, so that the heating sources are changed according to the state of the image forming apparatus. It is an object of the present invention to provide an image forming apparatus that controls the uniform distribution of heat of the fixing roller by appropriately switching between the use of the main heating source alone and the series use of the main heating source and the auxiliary heating source, thereby performing more appropriate fixing. .

According to a seventh aspect of the present invention, at least one of the main heating source and the auxiliary heating source is filled with a tungsten heating coil and an inert gas mainly composed of xenon gas or krypton gas. An object of the present invention is to provide an image forming apparatus in which a heating source is inexpensive, highly durable, and highly efficient even when a high output power is applied when heating to a fixing temperature and heating to a fixing temperature by using a radiant heater. And

According to the invention described in claim 8, the heat capacity of the heating coil of the main heating source is reduced by setting the color temperature of the tungsten heating coil of the main heating source to be 2500 K or more and 3500 K or less. It is an object of the present invention to provide an image forming apparatus that is capable of responding and prolonging the life of a heating coil.

[0016]

According to the first aspect of the present invention, there is provided an image forming apparatus comprising: a fixing roller heated by a heating source; In an image forming apparatus including a fixing unit that conveys paper while heating and pressurizing the paper with the fixing roller and the pressure roller and fixes the toner image on transfer paper, at least a heating source that heats the fixing roller is provided. It has a main heating source and an auxiliary heating source connected in series to a power supply circuit, and is connected in parallel with the auxiliary heating source to perform on / off operation. When the main heating source is on, the main heating source is directly connected to the power supply circuit. A first mode in which power is supplied from the power supply circuit only to the main heating source when connected, and when the power supply is off, the main heating source and the auxiliary heating source are supplied with power from the power supply circuit. By providing a switching means for switching a second mode, and has achieved the above objects.

According to the above construction, the fixing roller heated by the heating source and the fixing roller contact with the fixing roller and rotate together with the fixing roller, and the transfer paper on which the toner image is transferred is heated and heated by the fixing roller and the pressure roller. As a heating source that heats the fixing roller of the fixing unit that conveys while pressing and fixes the toner image on the transfer paper, at least a main heating source and an auxiliary heating source connected in series to a power supply circuit are provided. A first heating device connected in parallel with the auxiliary heating source to perform an on / off operation and directly connect the main heating source to the power supply circuit when on to supply power from the power supply circuit only to the main heating source;
Since the mode and the second mode in which the main heating source and the auxiliary heating source are supplied with power from the power supply circuit when they are off are switched, the state of the image forming apparatus such as at startup and during image forming operation is changed. The output of the heating source can be switched appropriately and inexpensively in accordance with this, the fixing roller can be quickly heated to a predetermined temperature, and the heating source can be used with a reduced output during the minimum image forming operation. Can be extended.

In this case, for example, when the image forming apparatus needs rapid heating of the fixing roller at the time of power-on and at the time of returning from the standby state, the image forming apparatus may be configured to perform the above-described operation. The fixing roller may be heated in the second mode by heating the fixing roller in one mode and heating the fixing roller to a predetermined fixing temperature.

According to the above configuration, when rapid heating of the fixing roller is required, for example, when the power is turned on or when returning from the standby state, the fixing roller is heated in the first mode, and the fixing roller is brought into a predetermined mode. When the fixing roller is heated to the fixing temperature, the fixing roller is heated in the second mode. Therefore, when the fixing roller is heated to the fixing temperature when the power is turned on and when returning from the standby state, the power is supplied with a high output to perform image formation. During operation, the power can be supplied at the rated output, the rise time can be shortened, the power consumption can be reduced by using efficient power, and the heating source can have a long life.

Further, for example, when the image forming apparatus needs rapid heating of the fixing roller at the time of power-on or at the time of returning from a standby state, the first image forming apparatus may be configured to use the first image forming apparatus. When the fixing roller is heated in a mode and the fixing roller is heated to a predetermined fixing temperature, the first mode and the second mode are switched based on a detection result of a detection sensor that detects the temperature of the fixing roller. The fixing roller may be heated as appropriate.

According to the above configuration, when rapid heating of the fixing roller is required, for example, when the power is turned on or when returning from the standby state, the fixing roller is heated in the first mode, and the fixing roller is brought into a predetermined mode. When the fixing roller is heated to the fixing temperature, the first mode and the second mode are appropriately selected and the fixing roller is heated based on the detection result of the detection sensor for detecting the temperature of the fixing roller. When the temperature is low, or when the temperature at the end of the fixing roller rises when passing small-size transfer paper, the heat distribution can be adjusted appropriately to make the temperature distribution of the fixing roller uniform. Thus, more appropriate fixing can be performed.

Further, for example, as described in claim 4, the power supply circuit has a function of controlling the power supply to the main heating source and the auxiliary heating source in a phase control or a pulse form, and the image forming apparatus Are the first mode and the second mode
When heating the pressure roller by appropriately selecting a mode, the power supply circuit controls the phase control or the pulse-like control,
The average power in the first mode may be controlled to be substantially equal to the power in the second mode.

According to the above configuration, the power supply circuit is provided with a function of controlling the power supply to the main heating source and the auxiliary heating source in a phase control or a pulse-like manner, and the first mode and the second mode are appropriately selected and pressurized. When the roller is heated, the average power in the first mode is controlled to approximately the same power as the power in the second mode by controlling the power supply circuit to perform phase control or pulse-like control. Depending on the state, the main heating source can be used alone or the main heating source and the auxiliary heating source can be switched in series as appropriate, and efficient power can be used, and more appropriate fixing can be performed. At the same time, it is possible to extend the life of the heating source while reducing power consumption.

Further, for example, as set forth in claim 5, the main heating source and the auxiliary heating source are the first heating source and the auxiliary heating source.
The average power when the fixing roller is heated by appropriately selecting the mode and the second mode is H1, the power consumption in the first mode is H2, the power consumption in the second mode is H3, and the image forming apparatus is used. A1 represents power consumption other than power consumption in the fixing unit in the standby state, A2 represents power consumption other than power consumption in the fixing unit during image forming operation of the image forming apparatus, and A2 represents rated power of the image forming apparatus. M, H3 ≦ M−A2,
When H1 ≦ M−A2, power that satisfies H2 ≦ M−A1 may be consumed.

According to the above configuration, the main heating source and the auxiliary heating source are appropriately selected from the first mode and the second mode, and the average power when heating the fixing roller is H1, and the power consumption in the first mode is H1. H2, the power consumption in the second mode is H3, the power consumption other than the power consumption of the fixing unit in the standby state of the image forming apparatus is A1, and the consumption other than the power consumption of the fixing unit during the image forming operation of the image forming apparatus is A1. When the power is A2, the rated power of the image forming apparatus is M, and when H3 ≦ M−A2 and H1 ≦ M−A2,
Since the power that satisfies the condition of H2 ≦ M−A1 is consumed, the heating source can be used alone or the main heating source and the auxiliary heating source can be used depending on the state of the image forming apparatus with respect to the rated power of the image forming apparatus. In addition to being able to perform switching in series as appropriate, the configuration of the main heating source and the auxiliary heating source can be set so that the power consumption at this time is constant, and more appropriate fixing can be performed. Efficient power usage can be used to reduce power consumption.

Further, for example, the main heating source and the auxiliary heating source may have different heat generation distributions in the axial direction of the fixing roller.

According to the above configuration, the main heating source and the auxiliary heating source have different heat distributions in the axial direction of the fixing roller. Therefore, the heating source is changed to the main heating source according to the state of the image forming apparatus. By appropriately switching between single use and series use of the main heating source and the auxiliary heating source, the heat distribution of the fixing roller can be uniformly controlled, and more appropriate fixing can be performed.

Further, for example, at least one of the main heating source and the auxiliary heating source has a heating coil of tungsten and a xenon gas or a krypton gas as main components in a sealed tube. A radiant heater filled with an inert gas may be used.

According to the above configuration, at least one of the main heating source and the auxiliary heating source is a radiant heater in which a heating coil of tungsten and an inert gas containing xenon gas or krypton gas as a main component are sealed in a sealed tube. Therefore, the heating source can be made inexpensive, highly durable and highly efficient even if the power is supplied at a high output when the temperature is raised to the fixing temperature by heating.

Further, for example, the tungsten heating coil of the main heating source may have a color temperature of 2500K or more and 3500K or less.

According to the above arrangement, the tungsten heating coil serving as the main heating source has a color temperature of 2500 K or more.
Since the temperature is set to 500K or less, the heat capacity of the heating coil of the main heating source can be reduced to achieve high response, and the life of the heating coil can be prolonged.

[0032]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 and 2 show a first embodiment of the image forming apparatus of the present invention. FIG. 1 shows an image to which the first embodiment of the image forming apparatus of the present invention is applied. FIG. 1 is a schematic front view of a forming apparatus.

In FIG. 1, the image forming apparatus 1 has a photoconductor 3 disposed in a main body housing 2. A charging unit 3, an optical writing unit 4, a developing unit 5, A transfer unit 6, a cleaning unit 7, and the like are provided, and transfer paper 9 is conveyed between a transfer unit 6 and the photoconductor 3 from a paper supply unit 8 provided below the main body housing 2. come. Further, a fixing unit 10 is disposed downstream of the transfer unit 6 in the transport direction of the transfer paper 9 (above the transfer unit 6 in FIG. 1), and a photoconductor is provided between the charging unit 3 and the developing unit 5. 3 is irradiated with laser light L modulated with image data from the optical writing unit 4, and an electrostatic latent image is formed on the photoconductor 3.

The charging unit 3 uniformly charges the photosensitive member 3 which is driven to rotate counterclockwise in FIG. 1 to a predetermined potential. The laser beam L modulated by the image data is emitted to form an electrostatic latent image. The photoreceptor 3 on which the electrostatic latent image is formed is developed with a developer, for example, a toner, attached thereto in the developing unit 5, and a toner image is formed on the surface of the photoreceptor 3.

When the portion on which the toner image has been formed is rotated to a position facing the transfer unit 6, the transfer paper 9 conveyed from the paper feed unit 8 transfers the transfer paper 9 between the transfer unit 6 and the photosensitive member 3. The toner image on the photoconductor 3 is transferred onto the transfer paper 9 by the transfer unit 6 and is transferred to the fixing unit 10.

In the paper supply section 8, a plurality of transfer papers 9 are stored in a paper supply cassette 11 which can be attached and detached in the direction of arrow a in FIG. It is placed on the provided middle plate 12 and is pressed against the paper feed roller 14 via the arm 13 by a spring (not shown) disposed below the middle plate 12.

When the paper feed roller 14 is rotated by a signal from a control unit (not shown), the paper feed unit 8
The transfer paper 9 at the top in 1 is transported to the registration rollers 16 on the downstream side while preventing double feed by the separation pad 15.

The registration roller 16 adjusts the timing so as to synchronize with the image on the photoconductor 3 and sends out the transfer paper 9 between the photoconductor 3 and the transfer unit 6.

The image forming apparatus 1 conveys the transfer paper 9 on which the image on the photoreceptor 3 has been transferred by the transfer unit 6 to the fixing unit 10.
The fixing unit 10 includes a fixing roller 17 and a pressure roller 18 disposed so as to be in pressure contact with the fixing roller 17. The transfer paper 9 is conveyed between the fixing roller 17 and the pressure roller 18. come. The fixing unit 10 fixes the toner image on the transfer paper 9 by applying heat and pressure while nipping and transferring the transfer paper 9 between the fixing roller 17 and the pressure roller 18. The image forming apparatus 1 discharges the transfer paper 9 on which the toner image is fixed from a discharge port 19 to a discharge tray 21 formed on an upper part of the main body housing 2 with a discharge roller 20 with an image forming surface facing downward. .

The paper discharge tray 21 is provided with a paper discharge stopper 22, and the paper discharge stopper 22 is slidable in the direction of arrow b in FIG. 1 in order to correspond to the size of the transfer paper 9 to be discharged. I have. The main body cover 2 a constituting the paper discharge tray 21 can be opened around the rotation fulcrum 23.

A case 24 is housed in the main body housing 2 below the openable and closable main body cover 2a. The case 24 includes a power supply 25, and electric components such as a printed board 26 which is a print engine driver board. , A control device and a controller board 27 are housed therein.

In the image forming apparatus 1, an operation surface is disposed on an upper front portion (an upper right portion in FIG. 1) of the main body casing 2.
The operation panel 28 is provided so as to protrude from the surface of the main body housing 2.

Further, in the image forming apparatus 1, a paper feed tray 29 is rotatably mounted on a side surface of the main body 2 by a pin 30.

On the other hand, the photoreceptor 3 having been transferred to the transfer paper 9 is further rotated to remove the residual toner by the cleaning unit 7, and then charged by the charging unit 3 to be used for image formation again. Is done.

As shown in FIG. 2, the fixing section 10 includes a fixing roller 17 and a pressure roller 18 disposed so as to be in pressure contact with the fixing roller 17.
Has a metal base 17a of a thin pipe of Al or Fe having a thickness of about 0.2 to 0.8 mm, and a surface release layer 17b is formed on an outer surface of the metal base 17a. In the fixing roller 17, as a heating source 31, a heating heater (main heating source) 32 and a heating heater (auxiliary heating source)
33, the heater 32 and the heater 3
3 is connected in series to a power supply circuit 34, and a switch (switching means) 35 is connected to a connection portion between the heater 32 and the heater 33. Heater 3
2 is a power supply circuit 34 when the switch 35 is on.
Is connected directly to the power supply circuit 34 in a state of being connected in series with the heater 33 when the switch 35 is off. The power supply circuit 34 includes a commercial power supply 3
6 is connected, and the power supply circuit 34
The commercial power supply 36 is controlled by the SSR according to the output of a temperature detection sensor (detection sensor) (not shown) that detects the surface temperature of the power supply. The image forming apparatus 1 turns on the SSR drive signal,
A first mode in which the switch 35 is turned on, and the commercial power supply 36 is applied only to the heater 32 from the power supply circuit 34;
The drive signal is turned off, the switch 35 is turned off, and the heater 32 and the heater 33 are connected in series to connect a commercial power source 36.
And the second mode in which is applied from the power supply circuit 34. The power supply circuit 34 includes the heater 32
And the power supply to the heater 33 is controlled in phase or in pulse form.

As described above, the transfer paper 9 on which the toner image 37 has been transferred is guided between the fixing roller 17 and the pressure roller 18 by the guide plate 38 and is conveyed to the fixing unit 10 by the heating heater. Fixing roller 17 heated by 32, 33
The transfer paper 9 to which the toner image 37 has been transferred is conveyed while being heated by the pressure roller 18 and the toner image 37 is fixed to the transfer paper 9.

The heater 32 is a heater of 8.33 Ω. Tungsten is used as a heating coil, and xenon gas or krypton gas is used as an inert gas for suppressing the evaporation rate of tungsten. It is sealed in a glass tube. Further, the heater 33 is a 4.17Ω heater, uses tungsten as a heating coil, and uses a xenon gas or a krypton gas as a main component as an inert gas for suppressing an evaporation rate of the tungsten in a glass tube. It is enclosed. Further, when the heater 32 is energized in the first mode, the color temperature becomes 2500 K or more and 350 K or more.
The tungsten filament is set to 0K or less, preferably 3000K. Therefore, when the 100 V AC commercial power supply 36 is supplied to the image forming apparatus 1, in the first mode, the heating source 31 supplies the commercial power supply 36 only to the heater 32, and
The power becomes 0 W, and in the second mode, the commercial power supply 36 is supplied to the heater 32 and the heater 33 connected in series, and the power becomes 800 W.

That is, the heater 32 and the heater 33 have an average power H1 for heating the fixing roller 17 by appropriately selecting the first mode and the second mode, a power consumption H2 in the first mode, and a power consumption H2 in the first mode. The power consumption in the two modes is H3, the power consumption other than the power consumption in the fixing unit 10 in the standby state of the image forming apparatus 1 is A1, and the power consumption other than the power consumption in the fixing unit 10 in the image forming operation of the image forming apparatus 1 is A1. Let A2 be the power consumption, M be the rated power of the image forming apparatus 1, and H3 ≦ M−A2, H1 ≦
In the case of M-A2, power that satisfies H2 ≦ M-A1 is consumed.

Next, the operation of the present embodiment will be described. The image forming apparatus 1 is supplied with a 100 V commercial power supply 36, and has an energy saving mode in which power supply to the heating source 31 of the fixing unit 10 is stopped in a standby state to reduce power consumption.

When a print signal is input to the controller board immediately after power-on or when a print signal is input to the controller board from the energy saving mode, the image forming apparatus 1
The SR drive signal is turned on, the switch 35 is turned on, and the commercial power supply 36 is turned on from the power supply circuit 34 only to the heater 32 to supply and supply the maximum power.

The rated power of the entire image forming apparatus 1 is set to 1500 W. When the power of the image forming apparatus 1 is turned on or when returning from the energy saving mode, a series of image forming operations is performed. When the system and the paper transport system are not driven, the power consumption is 300 W
In this state, the rated power is maintained even when the heating source 31 is energized in the first mode in this state.

In this state, when the heating source 31 is heated in the first mode, as described above, the heating source 32 as the heating source 31 is rapidly heated at a high output of 1200 W, and the filament of the heating source 32 is further heated. Is 3000K higher than the normal color temperature of 2500K,
Since the heat capacity of the filament is small, the filament glows red from the beginning of energization, and the time for radiating radiant heat is shortened by about 1 second as compared with the related art, and the filament is rapidly heated.

Therefore, when turning on the power and returning from the energy saving mode, the fixing roller 17 can be quickly heated to the fixing temperature.

The image forming apparatus 1 includes a fixing roller 1
7 is heated to the fixing temperature from the detection result of the temperature detection sensor, the SSR drive signal is turned off, the switch 35 is turned off, and the heater 32 and the heater 3
The commercial power supply 36 is supplied in a state where the power supply 3 is connected in series. In this state, an electrostatic latent image and a toner image are formed on the photoconductor 3, and a paper transport operation for transporting the transfer paper 9 from the paper supply unit 8 between the photoconductor 3 and the transfer unit 6. And perform photoreceptor 3
A series of image forming operations of transferring the toner image formed on the transfer paper 9 to the fixing unit 10 is performed. The image forming apparatus 1 is set so that the temperature of the fixing roller 17 has reached a predetermined fixing temperature when the transfer paper is conveyed to the attachment section 10.

When the transfer paper 9 on which the toner image is transferred is conveyed to the fixing unit 10, the image forming apparatus 1 conveys the transfer paper 9 while heating the transfer paper 9 with the fixing roller 17 and the pressure roller 18, and transfers the transfer paper 9. The toner image on the paper 9 is fixed on the transfer paper 9, and the transfer paper 9 having been fixed is discharged from a discharge port 19 to a discharge roller 20.
To discharge the image onto the paper discharge tray 21 with the image forming surface facing downward.

In the image forming mode, the power supply circuit 34 controls the power supply to the heater 32 and the heater 33 in this image forming mode, based on the output of the temperature detection sensor, so that the temperature of the fixing roller 17 is controlled. Is controlled to the fixing temperature.

The image forming apparatus 1 is in a state where a series of image forming systems and paper conveying operations are being performed.
Increases to 700 W or less, but even if the heating source 31 is energized in the second mode in this state, the rated power of 1500 W is maintained.

When the color temperature of the heater 32 is 3000
Since the K filament is thin and has a short life, there is a possibility that the filament will break if used continuously in the first mode. However, in the image forming mode, the fixing unit 1 is not used.
Since the 0 heating source 31 is operated in the second mode, the partial pressure of the heater 32 and the heater 33 is reduced, and the life of the filament is short, which is equivalent to a conventional use state.

The image forming apparatus 1 may heat the fixing roller 17 by appropriately selecting the first mode and the second mode according to the output of the temperature detection sensor. The inert gas xenon gas or krypton gas used in the heater 32 suppresses the evaporation of the filament, suppresses the removal of heat from the filament by convection, suppresses the loss of radiant heat, and increases the efficiency. Since the effect of improvement has been confirmed, by switching between the first mode and the second mode and using the heater 32, the life can be extended as compared with the conventional use state.

FIGS. 3 and 4 are views showing a second embodiment of the image forming apparatus of the present invention, and FIG. 3 is a diagram showing an image to which the second embodiment of the image forming apparatus of the present invention is applied. FIG. 2 is a schematic configuration diagram of a fixing unit 40 and a power supply system of the forming apparatus.

The present embodiment is applied to an image forming apparatus similar to the image forming apparatus of the first embodiment. In the description of the present embodiment, the first embodiment will be described. The same components as those in the embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted. Also, portions not illustrated are described using the same reference numerals used in the first embodiment as needed. I do.

Although not shown, the fixing section 40 of the image forming apparatus 1 includes the fixing roller 17 and the pressure roller 18 as described above.
The fixing roller 17 includes a heater 41 and a heater 42 shown in FIG.

The heater 41 and the heater 42 are connected in series to the power supply circuit 34, and a switch 35 is connected to a connection portion between the heater 41 and the heater 42. The heater 41 is directly connected to the power supply circuit 34 when the switch 35 is on, and connected to the power supply circuit 34 in series with the heater 42 when the switch 35 is off. Is done. A commercial power supply 36 is connected to the power supply circuit 34. The power supply circuit 34 switches the commercial power supply 36 to SS in accordance with an output of a temperature detection sensor (not shown) for detecting the surface temperature of the fixing roller 17.
Control with R. The image forming apparatus 1 turns on the SSR drive signal, turns on the switch 35, applies the commercial power source 36 only to the heater 41 from the power supply circuit 34, and turns off the SSR drive signal. A second mode in which the heater 35 and the heater 42 are connected in series and the commercial power source 36 is applied from the power supply circuit 34;
To control.

The heater 41 has a heating coil made of tungsten, and contains xenon gas or krypton gas as a main component as an inert gas for suppressing the evaporation rate of tungsten in a glass tube. Tungsten of the heater 41 is disposed such that the heat generation distribution in the longitudinal direction of the heater 41 is such that the heat generation intensity increases at both ends in the longitudinal direction as shown by a curve 41H in FIG. Further, the heater 42 is formed by using tungsten as a heat generating coil and enclosing xenon gas or krypton gas as a main component in a glass tube as an inert gas for suppressing the evaporation rate of tungsten. The distribution of heat generated in the longitudinal direction of the heater 41 by the tungsten of the heater 42 is represented by a curve 42H in FIG.
As shown by, they are arranged in a state in which the heat generation intensity increases at the center in the longitudinal direction.

Therefore, in the fixing section 40 of the image forming apparatus 1 of the present embodiment, in the first mode, the switch 35 is turned on, and only the heater 41 is supplied from the power supply circuit 34 to the commercial power supply. 36 is full wave input and maximum power is 12
Power is supplied and supplied at 00 W, and heating is performed to a predetermined temperature.

At this time, the heating distribution of the heater 41 is large, as shown by the curve M1 in FIG. 4, and is particularly large at both ends in the longitudinal direction.

Therefore, the fixing roller 17 usually generates heat in the bearing portion and the driving gear, and the fixing roller 17
Temperature distribution at both ends tends to be lower than or equal to a predetermined temperature during the initial rotation.
Is particularly large at both ends in the longitudinal direction, so that the temperature distribution becomes uniform in the longitudinal direction (axial direction) of the fixing roller 17.

The image forming apparatus 1 includes the fixing roller 1
When the temperature of the heater 7 reaches a predetermined temperature, the switch 35 is turned off, the second mode is set, the heater 41 and the heater 42 are connected in series, and power is supplied at a power of about 800 W.
The above-described series of image forming processes operate to form a toner image on the transfer paper 9 and convey the transfer paper 9 to the fixing unit 40. The fixing unit 40 is set so that the fixing roller 17 reaches a predetermined temperature at this time. At this time, the image forming apparatus 1
The power supply circuit 34 may control the power supply to the heater 32 and the heater 33 based on the output of the temperature detection sensor to control the temperature of the fixing roller 17 to the fixing temperature.

In the second mode, as shown by the curve M2, the curve H1 and the curve H2 have an overlapping heat distribution, and when the heat transfer to the bearing portion and the drive gear of the fixing roller 17 is considered, The fixing roller 17 has a uniform temperature distribution in the longitudinal direction.

In the case of continuously forming an image with the maximum sheet passing width during the image formation, the image formation is performed by energizing the second mode.
When the selected transfer sheet 9 has a narrow sheet passing width such as A4 vertical sheet passing, wasteful energy is consumed in the non-sheet passing portion of the fixing roller 17.

To cope with this, the image forming apparatus 1 responds by alternately energizing the first mode and the second mode in accordance with an instruction from the controller. At this time, the power supply circuit 34
In the mode, the maximum output is performed. In the second mode, the phase control or the pulse-like control is performed. By controlling the power to 67%, the optimum control is performed within the rated power.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in each of the above embodiments, xenon gas or krypton gas is sealed in the heaters 32 and 33 and the heaters 41 and 42 to suppress the evaporation rate of tungsten. A gas containing a chlorine or bromine component to be used may be sealed.

[0075]

According to the image forming apparatus of the first aspect of the present invention, the fixing roller heated by the heating source and the transfer roller on which the toner image has been transferred are rotated by rotating together with the fixing roller in contact with the fixing roller. A main heating source connected in series to at least a power supply circuit as a heating source for heating a fixing roller of a fixing unit that conveys the toner image onto the transfer paper while heating and pressing with a fixing roller and a pressure roller and fixing the toner image on transfer paper. An auxiliary heating source is provided, and the switching means is connected in parallel with the auxiliary heating source to perform on / off operation. When the auxiliary heating source is turned on, the main heating source is directly connected to the power supply circuit, and only the main heating source is connected to the main heating source from the power supply circuit. And a second mode in which power is supplied from the power supply circuit to the main heating source and the auxiliary heating source when the power supply is off. As described above, the output of the heating source can be appropriately and inexpensively switched according to the state of the image forming apparatus, and the fixing roller can be quickly heated to a predetermined temperature. It is possible to prolong the service life of the heating source by using the heating source while suppressing it.

According to the image forming apparatus of the present invention, when the fixing roller needs to be rapidly heated when the power is turned on and when returning from the standby state, the fixing roller is heated in the first mode. When the fixing roller is heated to a predetermined fixing temperature, the fixing roller is heated in the second mode. Therefore, when the fixing roller is heated to the fixing temperature when the power is turned on and when returning from the standby state, the fixing roller is heated. It can be energized at high output and can be energized at rated output during image forming operation, shortening the rise time, reducing power consumption by using efficient power, and extending the life of the heating source. Can be

According to the image forming apparatus of the third aspect, when the fixing roller needs to be rapidly heated when the power is turned on and when returning from the standby state, the fixing roller is heated in the first mode. Then, when the fixing roller is heated to a predetermined fixing temperature, the first mode and the second mode are appropriately selected to heat the fixing roller based on the detection result of the detection sensor that detects the temperature of the fixing roller. Heat distribution to make the temperature distribution of the fixing roller uniform when the temperature at the end of the fixing roller is extremely low or when the temperature at the end of the fixing roller is increased when small-sized transfer paper is passed. Adjustment can be appropriately performed, and more appropriate fixing can be performed.

According to the image forming apparatus of the present invention, the power supply circuit has a function of controlling the power supply to the main heating source and the auxiliary heating source in a phase control or a pulse-like manner.
When the pressure roller is heated by appropriately selecting the mode and the second mode, the power supply circuit controls the phase control or the pulse-like control,
Since the average power in the first mode is controlled to be substantially the same as the power in the second mode, the main heating source can be used alone and the main heating source and the auxiliary heating source can be used depending on the state of the image forming apparatus during the image forming operation. In addition to being able to switch the use in series as appropriate, efficient use of electric power can be performed, more appropriate fixing can be performed, and a long life of the heating source can be achieved while reducing power consumption. it can.

According to the image forming apparatus of the present invention, the main heating source and the auxiliary heating source are switched between the first mode and the second mode.
The average power when heating the fixing roller by appropriately selecting the mode is H1, the power consumption in the first mode is H2, the power consumption in the second mode is H3, and the power in the fixing unit in the standby state of the image forming apparatus. A1 is power consumption other than power consumption, and A1 is power consumption other than power consumption in the fixing unit during the image forming operation of the image forming apparatus.
2. Assume that the rated power of the image forming apparatus is M, and H3 ≦ MA.
2. When H1 ≦ M−A2, the power that satisfies H2 ≦ M−A1 is consumed, so that the main heating source is used as a single heating source in accordance with the state of the image forming apparatus with respect to the rated power of the image forming apparatus. The use and the series use of the main heating source and the auxiliary heating source can be appropriately switched, and the configuration of the main heating source and the auxiliary heating source can be set so that the power consumption at this time is constant. Appropriate fixing can be performed, and power consumption can be reduced by efficiently using power.

According to the image forming apparatus of the present invention, the main heating source and the auxiliary heating source have different heat distributions in the axial direction of the fixing roller. Accordingly, the use of the main heating source alone or the series use of the main heating source and the auxiliary heating source can be appropriately switched to uniformly control the heat distribution of the fixing roller, and more appropriate fixing can be performed. .

According to the image forming apparatus of the present invention, at least one of the main heating source and the auxiliary heating source is provided in the sealed tube with a heating coil made of tungsten and a main component comprising xenon gas or krypton gas. Since the radiation heater filled with the active gas is used, the heating source can be made inexpensive, highly durable, and highly efficient even if the power is supplied at a high output when the temperature is raised to the fixing temperature.

According to the image forming apparatus of the present invention, since the color temperature of the tungsten heating coil of the main heating source is 2500 K or more and 3500 K or less, the heat capacity of the heating coil of the main heating source is reduced. It is possible to reduce the number of the coils, thereby increasing the response, and to prolong the life of the heating coil.

[Brief description of the drawings]

FIG. 1 is a front schematic configuration diagram of an image forming apparatus to which a first embodiment of the image forming apparatus of the present invention is applied.

FIG. 2 is a main part configuration diagram of a fixing unit and a power supply system of the image forming apparatus of FIG. 1;

FIG. 3 is a main part configuration diagram of a fixing unit and a power supply system of an image forming apparatus to which a second embodiment of the present invention is applied.

4 is a diagram showing heat generation distribution characteristics of the two heaters in FIG. 3 and heat distributions in a first mode and a second mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body housing 2a Main body cover 3 Charging part 4 Optical writing part 5 Developing part 6 Transfer part 7 Cleaning part 8 Paper supply part 9 Transfer paper 10 Fixing part 11 Paper cassette 12 Middle plate 13 Arm 14 Paper supply Roller 15 Separation pad 16 Registration roller 17 Heat fixing roller 17a Metal substrate 17b Surface release layer 18 Pressure roller 19 Discharge port 20 Discharge roller 21 Discharge tray 22 Discharge stopper 23 Rotating fulcrum 24 Case 25 Reference 26 Printed circuit board 27 Controller Board 28 Operation panel 29 Feed tray 30 Pin 31 Heat source 32, 33 Heater 34 Power circuit 35 Switch 36 Commercial power supply 37 Toner image 38 Guide plate 40 Fixing unit 41, 42 Heater 43 Heat source

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) H05B 3/00 H05B 3/00 310E 310J 335 335 F term (reference) 2H033 AA03 AA23 AA30 AA32 BA25 BA27 BA30 BB01 BB18 BB28 CA07 CA28 CA30 CA46 3K058 AA45 AA81 BA18 CA12 CA23 CA61 CB06 CB07 CD01 CE17 CE23 DA02 5H323 AA36 BB17 CA08 CB04 CB42 DA01 FF01 GG04 HH02 KK05 LL18 MM08 MM11

Claims (8)

[Claims] An image forming apparatus comprising: a fixing roller heated by a heating source; a fixing roller which contacts the fixing roller and rotates together with the fixing roller; and heats and presses a transfer sheet on which a toner image is transferred by the fixing roller and the pressing roller. In an image forming apparatus including a fixing unit that conveys and fixes the toner image on transfer paper,
As a heating source for heating the fixing roller, at least a main heating source and an auxiliary heating source connected in series to a power supply circuit, and connected in parallel with the auxiliary heating source to perform an on / off operation and turn on. A first mode in which the main heating source is directly connected to the power supply circuit to supply power from the power supply circuit only to the main heating source, and the power supply is supplied to the main heating source and the auxiliary heating source when off. An image forming apparatus comprising: a switching unit that switches between a second mode in which power is supplied from a circuit and a second mode. 2. The image forming apparatus heats the fixing roller in the first mode when rapid heating of the fixing roller is required at the time of power-on and when returning from a standby state, and the like.
2. The image forming apparatus according to claim 1, wherein when the fixing roller is heated to a predetermined fixing temperature, the fixing roller is heated in the second mode. 3. The image forming apparatus heats the fixing roller in the first mode when rapid heating of the fixing roller is required, for example, when power is turned on and when returning from a standby state.
When the fixing roller is heated to a predetermined fixing temperature, the first mode and the second mode are appropriately selected based on the detection result of the detection sensor that detects the temperature of the fixing roller to heat the fixing roller. 2. The method according to claim 1, wherein
The image forming apparatus as described in the above. 4. The image forming apparatus according to claim 1, wherein the power supply circuit has a function of controlling the power supply to the main heating source and the auxiliary heating source in a phase control or a pulse-like manner. When the pressure roller is heated by appropriately selecting, the phase control or the pulse-like control is performed by the power supply circuit so that the average power in the first mode is substantially equal to the power in the second mode. The image forming apparatus according to claim 3, wherein the control is performed. 5. The main heating source and the auxiliary heating source,
The average power when heating the fixing roller by appropriately selecting the first mode and the second mode is H1, the power consumption in the first mode is H2, the power consumption in the second mode is H3, A1 represents power consumption other than power consumption of the fixing unit in the standby state of the image forming apparatus, A2 represents power consumption other than power consumption of the fixing unit during image forming operation of the image forming apparatus, and A2 represents power consumption of the image forming apparatus. The rated power is M, and H3 ≦ M
5. The image forming apparatus according to claim 4, wherein when -A2 and H1≤M-A2, power satisfying H2≤M-A1 is consumed. 6. The image forming apparatus according to claim 1, wherein the main heating source and the auxiliary heating source have different heat distributions in an axial direction of the fixing roller. apparatus. 7. At least one of the main heating source and the auxiliary heating source is a radiant heater in which a heating coil of tungsten and an inert gas containing xenon gas or krypton gas as a main component are sealed in a sealing tube. The image forming apparatus according to claim 1, wherein: 8. The image forming apparatus according to claim 7, wherein said tungsten heating coil of said main heating source has a color temperature of 2500 K or more and 3500 K or less.