JP2003215974A - Fixing device and image forming apparatus provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device achieving a reduction in temperature adjusting ripple in a fixing body due to a delay in response to the temperature detected by a temperature detecting means for detecting the temperature of the fixing body in a non-contact state and to provide an image forming apparatus provided with the same. <P>SOLUTION: Magnitude of the power supply to a heater 4 is controlled according to the temperature detected by the non-contact temperature sensor 5 in steps or continuously. <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 a fixing device for fixing an unfixed image on the recording material by heating the recording material carrying the unfixed image while contacting the fixing member, and an image forming apparatus including the fixing device. It is about.

[0002]

2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines and laser printers, a fixing device using a fixing roller as a fixing member heated by a heater as a heating means has been widely used.

In such a fixing device, a thermistor for maintaining the surface temperature of the fixing roller at a predetermined temperature, a thermo switch for cutting off the energizing path to the heater when the temperature of the fixing roller abnormally rises, and the like are provided on the surface of the fixing roller. Abutting.

However, since the fixing roller is a rotating body, the surface of the fixing roller may be damaged, such as scratches and abrasion marks, due to the sliding friction between these abutting objects and the fixing roller. Such scratches and wear on the surface of the fixing roller cause white lines,
It is generally known to cause image defects such as black streaks and defective fixing.

Therefore, it is conceivable to bring these abutting objects into contact with the fixing roller outside the image area, which is the passage area of the recording material, but it is impossible to detect the temperature in the image area and the fixing device is large. For this reason, recently, a non-contact type temperature detecting means has been considered which is brought into non-contact with the fixing roller in the image area.

As the non-contact type temperature detecting means,
For example, a casing having a transparent window for transmitting infrared rays, an infrared absorbing film serving as a radiant heat absorbing member made of a polymer material which is installed in the casing and absorbs infrared rays transmitted through the transparent window, and adheres to the infrared absorbing film. Infrared detecting thermistor element, which is a first temperature detecting element for detecting the temperature of the infrared absorbing film, and a temperature compensating second temperature detecting element for detecting the ambient temperature in the vicinity of the infrared detecting thermistor element. A non-contact temperature sensor including a thermistor element for a vehicle is known.

In this non-contact temperature sensor, the infrared rays transmitted through the transparent window of the casing are absorbed by the infrared absorbing film disposed immediately below the transparent window, so that the temperature of the infrared absorbing film rises. An infrared detecting thermistor element, which is arranged in close contact with the infrared absorbing film, detects the temperature change. Then, by detecting the temperature difference between the temperature detected by the thermistor element for infrared detection and the temperature detected by the thermistor element for temperature compensation as a potential difference in the bridge circuit, the absolute amount of infrared rays transmitted through the transmission window is detected. Then, the temperature of the fixing roller, which is the object to be measured, is measured without contact. This is because the substance emits infrared rays (accurately, radiant energy, but most of the radiant energy is in the infrared wavelength range, so it is referred to as infrared here) with an intensity according to its temperature. It is a kind of method to detect the temperature and obtain the temperature.

[0008]

In the fixing device provided with the non-contact temperature sensor as described above, it takes a relatively long time to change the ambient temperature, so that a short time such as a temperature control ripple of the fixing roller may occur. Changes in temperature mainly appear as changes in temperature detected by the thermistor element for infrared detection.
Also, before the non-contact temperature sensor detects the temperature change of the fixing roller, the temperature change of the fixing roller → the change of the infrared ray amount →
Change in temperature of infrared absorption film → Change in detection temperature of thermistor element for infrared detection and long path.

The infrared detection thermistor element has a structure similar to that in the case where the same type thermistor element is directly contacted with the fixing roller.
There is a problem that the response is delayed for about 1 to several seconds.

Although the cause of this has not been investigated exactly,
Since it takes a long path to detect the temperature, the results of various chain-like physical changes are measured, and in particular, the temperature change of the infrared absorption film due to the change of the infrared amount is likely to be delayed, so that fixing Since the front side of the infrared absorbing film that directly receives the infrared rays from the roller absorbs more infrared rays than the back side, it takes time for the temperature change on the front side of the infrared absorbing film to transfer heat evenly in the cross-sectional direction of the infrared absorbing film. It is considered that in the case of a sensor in which the infrared detection thermistor element is fixed on the back side of the infrared absorption film, the response is more likely to be delayed.

When a fixing roller having a small change in temperature of the fixing roller for a few seconds and a large heat capacity is used, the effect of such a delay in response is small, but a large change in temperature of the fixing roller for a few seconds has a small heat capacity. When a roller is used, this problem is serious because it leads to an increase in temperature control ripple.

Therefore, the present invention provides a fixing device and a fixing device capable of reducing the temperature control ripple of the fixing body due to a delay in response at the time of temperature detection of the temperature detecting means for detecting the temperature of the fixing body in a non-contact state. An object of the present invention is to provide an image forming apparatus provided with.

[0013]

According to the present application, the above object is to provide a fixing body, a heating means for receiving electric power from a power source to heat the fixing body, and a temperature detecting means for detecting the temperature of the fixing body. And a control means for controlling the electric power supplied from the power supply to the heating means so as to maintain the fixing body at a predetermined target temperature based on the temperature detected by the temperature detection means, and carry an unfixed image. A fixing device for fixing the unfixed image on the recording material by heating the recording material while contacting the fixing body, wherein the temperature detecting means is a radiant heat absorbing member for absorbing heat radiated from the fixing body. A first temperature detecting element for detecting the temperature of the radiant heat absorbing member and a second temperature detecting element for detecting an ambient temperature in the vicinity of the radiant heat absorbing member, and the first detected temperature value of the first temperature detecting element And the second temperature above In the fixing device configured to estimate and detect the surface temperature of the fixing body based on a preset data table corresponding to the combination with the second detected temperature value of the intelligent element, the control means includes the temperature detection means. It is achieved by the first invention that the electric power value from the power supply to the heating means is changed and controlled stepwise or continuously corresponding to the temperature detected by.

According to the present application, in the first aspect of the present invention, the control means has a small fluctuation range of the electric power value from the power source to the heating means based on the temperature detected by the temperature detecting means. It is also achieved by the second invention that is modified and controlled as follows.

Further, according to the present application, in the first or second invention, the control means sets the electric power value from the power source to the heating means in accordance with the operating condition of the fixing device. It is also achieved by the third invention.

According to the present application, the above object is achieved by the control means according to any one of the first to third inventions,
It is also achieved by the fourth invention in which the electric power value from the power source to the heating means is set in correspondence with the fixing process and the fixing process.

Further, according to the present application, in the object according to any one of the first to fourth inventions, the control means has a power value from the power source to the heating means corresponding to the operating condition of the fixing member. It is also achieved by the fifth invention in which is set.

According to the present application, the above object is achieved by the control means according to any one of the first to fifth inventions,
It is also achieved by the sixth invention in which the electric power value from the power source to the heating means is set according to the presence or absence of the recording material in the fixing device.

Further, according to the present application, the above object is an image forming apparatus for recording an image formed by a series of image forming processes on a recording material, and the image forming apparatus according to any one of the first to sixth inventions. It is also achieved by a seventh aspect of the present invention including a fixing device.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described.

FIG. 1 is a sectional view showing the schematic arrangement of a fixing device provided in the image forming apparatus according to this embodiment.

In the image forming apparatus according to the present embodiment, although not shown in the figure, an image carrier for carrying an electrostatic latent image on the surface thereof, and a surface of the image carrier for removing electric charges are not shown. Exposure device, charging device for charging the surface of the image bearing member to a desired potential, exposing means for exposing the image bearing member charged by the charging device to form an electrostatic latent image, on the image bearing member There is provided a developing device for developing the electrostatic latent image of 1) with a developer to make it visible as a toner image, a transfer device for transferring the toner image on the image carrier by the developing device to a recording material, and the like.

Further, a fixing unit 1 which is a fixing device for heating and pressing the toner image transferred onto the recording material by the transfer means to fuse and fix the toner image on the recording material is arranged at a predetermined position of the image recording apparatus. A desired image can be obtained by appropriately performing each process of image formation by each member. As the recording material, recording paper, OHP paper or the like is used.

Next, the structure of the fixing unit 1 will be described in detail.

As shown in FIG. 1, the fixing unit 1 includes a fixing roller 2 as a fixing member, a pressure roller 3, a heater 4 as a heating means, and a non-contact temperature sensor 5 as a temperature detecting means.
And a control means (not shown).

The fixing roller 2 has an outer diameter of 40 mm and a thickness of 0.
This is a roller in which the surface of a 7 mm iron cored bar is covered with a release layer of a 30 μm PFA tube.

The pressure roller 3 is arranged in pressure contact with the fixing roller 2 and has an outer diameter of 30 mm and a core metal of iron coated with a silicone rubber of 5 mm thickness and a release layer of a PFA tube of 50 μm. is there.

The nip width of the nip region formed by the pressure contact between the fixing roller (heating member) 2 and the pressure roller (backup member) 3 is 5.5 mm.

The toner T on the recording material S is fixed on the recording material S by being heated and pressed in the nip region while being nipped and conveyed by the fixing roller 2 and the pressure roller 3.

The heater 4 is arranged inside the fixing roller 2 and heats the fixing roller 2 from the inside.

The non-contact temperature sensor 5 is arranged in non-contact with the surface of the fixing roller 2 so as to detect the temperature of the fixing roller 2.

In this embodiment, the surface temperature of the fixing roller 2 is maintained at a predetermined set temperature (printing temperature) or a standby temperature during non-fixing (standby temperature) based on the data from the non-contact temperature sensor 5. ing.

Next, the structure of the non-contact temperature sensor 5 will be described in detail with reference to FIG.

As shown in FIG. 2, the non-contact temperature sensor 5 includes a casing 6 made of a material having high heat conductivity such as aluminum, and an infrared absorbing film 8 serving as a radiant heat absorbing member.
An infrared detection thermistor element 9 which is a first temperature detection element, and a temperature compensation thermistor element 10 which is a second temperature detection element.

The infrared absorbing film 8 is a heat-resistant film that absorbs infrared light emitted from the fixing roller 2 in the opening 7 provided on one surface of the casing 6, and the casing 6
Is provided so as to close the opening 7. The infrared absorption film 8 is a sheet material formed of a heat resistant resin such as polyimide and having a thickness of about 0.2 mm.

The infrared detecting thermistor element 9 is fixed to the inner surface of the casing 6 of the infrared absorbing film 8 by an adhesive agent or the like.

The temperature compensating thermistor element 10 is arranged near the infrared detecting thermistor element 9 and the casing 6 is provided.
It is designed to measure the ambient temperature inside. In this embodiment, a space having no opening is provided on the back surface side of the opening 7 of the infrared absorbing film 8.

The lead wires 11 of the infrared detecting thermistor element 9 and the temperature compensating thermistor element 10 are provided in the casing 6 and are respectively connected to sockets (not shown) so as to be taken out to the outside.

As shown in FIG. 3, the temperature compensating thermistor element 10 and the infrared detecting thermistor element 9 have a resistance R.
The bridge circuit of R2 and R3 is configured to be used, and the output thereof is output as a potential difference generated between the terminals A and B to detect the absolute amount of infrared rays absorbed by the infrared absorbing film 8. There is.

Next, the operation of the non-contact temperature sensor 5 will be briefly described.

First, when the infrared ray from the fixing roller 2 is incident on the infrared ray absorbing film 8 attached to the opening 7 of the casing 6, the infrared ray absorbing film 8 absorbs the infrared ray and the temperature of the infrared ray absorbing film 8 becomes the infrared ray amount. Rise accordingly.

The temperature of the infrared absorbing film 8 is
It is conducted to the thermistor element 9 for infrared detection, which is fixed in close contact with the back surface of the infrared absorbing film 8, and is detected as a change in resistance of the thermistor element.

The resistance of the infrared detection thermistor element 9 is
It is affected by the ambient temperature of the surroundings, and the temperature compensation thermistor element 10 is used to detect a temperature corresponding to the ambient temperature and eliminate the influence. Here, the casing is made of a material having a high thermal conductivity such as aluminum because the thermistor element 10 for temperature compensation with respect to a change in ambient temperature is used.
This is to improve the followability of.

Next, the control of the heater 4, which is the heating means, will be described with reference to FIG.

The heating means has a rated voltage of 100V.
A halogen heater that produces an output of 700 W when applied (AC power, 50 Hz) was used. In the conventional example, the output to the heater is controlled in two stages of 0 W and 700 W, but in the first embodiment, the output to the heater can be controlled in four stages of 0 W, about 250 W, about 500 W, and 700 W. The points are different.

For such multi-step control of the output to the heater, as shown in the current waveform diagram in FIG. 5, zero-cross wave number control for controlling whether to energize or not energize for each half wave of the power supply waveform is performed. The ratio of the number of waves energized in a unit time is 0 to 700 W, 0%, 35%, 70%, 1
The control was performed so as to be approximately 00%.

Based on the temperature detected by the non-contact temperature sensor, 700 W and 180 ° C. when the temperature is 180 ° C. or less in the conventional example.
In the above case, the output to the heater is controlled to 0 W, and the relationship between the output to the heater during image formation and the transition of the temperature detected by the non-contact temperature sensor when the temperature of the fixing roller is adjusted to 180 ° C. Is shown in FIG.

For reference, as shown in FIG. 4A, a thermistor element equivalent to the infrared detecting thermistor element of the non-contact temperature sensor was brought into contact with the fixing roller, and the temperature of the fixing roller was measured.

According to FIG. 4A, focusing on the temporal difference between the maximum temperature reaching point or the minimum temperature reaching point in the ripple of each sensor, the non-contact temperature sensor detects the temperature of the fixing roller in a contact state. A delay of about 2 to 3 seconds was observed as compared with the contact type temperature detecting means (hereinafter referred to as a contact temperature sensor).

In this embodiment, since the heat capacity of the fixing roller is small, the temperature of the fixing roller begins to drop immediately after the output to the heater reaches 0 W. Even though the contact temperature sensor detects the temperature decrease in about 1 second, the non-contact temperature sensor cannot detect the decrease in the fixing roller temperature for another 2 to 3 seconds. Is about 20 ℃
The temperature dropped by -25 ° C and a very large temperature control ripple was drawn. By the way, when the fixing device of this embodiment is controlled by the output control to the same heater as the conventional example by the output of the contact temperature sensor, the temperature decrease amount is about 5 to 10 ° C., and the increase of the temperature control ripple is unique to this sensor. It can be seen that the main cause is the delay in response.

Next, in the image forming apparatus of the first embodiment,
Based on the temperature detected by the non-contact temperature sensor, the output to the heater is controlled to 700W when the temperature is 180 ° C or lower and 500W when the temperature is 180 ° C or higher, and the image when the temperature of the fixing roller is adjusted to 180 ° C The transition of the output to the heater during formation and the temperature detected by the non-contact temperature sensor is shown in FIG. 4 (b).

As shown in FIG. 4B, the lowest temperature is 1
The temperature was suppressed to 70 ° C. to 175 ° C., the lower limit temperature substantially equal to that when the temperature was adjusted by the contact temperature sensor of the conventional example was realized, and the temperature ripple could be suppressed.

In the present embodiment, the power consumption of the heater during image formation is measured and converted into the power consumption per hour.
About 600 W of electric power was required during image formation. This value is called the required power here.

FIG. 6 is a graph showing the relationship between the electric power applied to the heater and the temperature decrease rate during the response delay period when the non-contact temperature sensor detects 180 ° C. or higher.

When the temperature detected by the non-contact temperature sensor is 180 ° C. or higher, the output to the heater is brought close to 0 W to 600 W, which is the required power, to suppress the temperature decrease rate in the response delay period and further suppress the lower limit temperature. You can read the point that is possible.

By the way, even if the temperature detected by the non-contact temperature sensor is 180 ° C. or higher, if the temperature is 700 W, the temperature is excessively high due to excessive heat applied to the fixing roller, and the temperature of the fixing roller is reduced to 1
It could not converge to 80 ° C.

In the present embodiment, the lower limit temperature can be maintained high because the output to the heater is 0 W in the conventional example, and the lower limit temperature is about 7 to
By controlling the heater with the output of 500W during the response delay period of the non-contact temperature sensor where the temperature of the fixing roller was dropping at a speed of 8 ° C / sec, the temperature drop during the response delay period was about 2 ° C / sec. This is because we were able to keep it to the limit.

An output value close to the required electric power is selected, and when the temperature is below the target temperature control temperature, the electric power is higher than the necessary electric power. By doing so, it can be seen that the temperature lowering rate in the response delay period can be alleviated and the lower limit temperature can be maintained even if the non-contact temperature sensor of this embodiment or the conventional example is used.

In order to prevent excessive temperature rise, it is preferable to select electric power smaller than the required electric power when the temperature detected by the sensor is higher than the target temperature. In this embodiment, it is understood that it is optimal to select the output of 500 W when the temperature is 180 ° C. or higher. As a result, as described above, the temperature ripple comparable to that of the contact temperature sensor can be realized even by using the non-contact temperature sensor of this embodiment and the conventional example.

It should be noted that it is of course the same as the existing image forming apparatus that the maximum output is preferably provided when the required electric power reaches the outermost large electric power of the heater.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The description of the same configuration as the first embodiment is omitted.

A large amount of heat is required because the recording material and the toner absorb a large amount of heat from the fixing roller during image formation with respect to the power consumption of the heater during standby. When the power consumption in each state was measured, it was converted into the power consumption per hour, and about 150 W was consumed during standby and about 600 W was consumed during image formation.

Therefore, as in the image formation of the first embodiment, 500 W at 180 ° C. or higher and 700 W at 180 ° C. or lower.
When the standby output is controlled with the heater output of 150, the required electric power of 150 W in the standby state greatly exceeds 500 W, and therefore the temperature of the fixing roller does not converge to 180 ° C. but rises excessively.

Therefore, an example in which the combination of outputs to the heaters used is switched between the standby mode and the image forming mode will be described as a second embodiment. Since the control of the heater during image formation is the same as that of the first embodiment, the description thereof is omitted. The power supply of the image forming apparatus is turned on and the image forming operation is ready to start immediately. When the image forming operation is not performed), the heater control will be described.

In the present embodiment, the temperature of the fixing roller in the standby state is adjusted to a temperature of 180 ° C.
The heater output is controlled to 250 W below 0 ° C. The temperature control ripple during standby was about 5 ° C or less.

As a comparison, the heater control of the conventional example based on the output value of the non-contact temperature sensor described in the first embodiment (18
The ripple during standby at 0 ° C. or higher was 0 W and at 180 ° C. or lower was 700 W. It was about 10 ° C.
Especially when the detected temperature of the non-contact temperature sensor is 180 ° C or less, the difference from the required power of 150 W is about 5 when the high heater output is used.
It is as large as 50 W, and the overshoot on the temperature rising side during the detection delay period is severe. In the second embodiment, the output to the heater near the required power is 0 W at 180 ° C. or higher and 2 at 180 ° C. or lower.
By controlling at 50W, we have succeeded in suppressing the overshoot small.

The contact temperature sensor uses the same heater control system as in the conventional example (0 W at 180 ° C. or higher, 70 W at 180 ° C. or lower).
0W), the temperature control ripple during standby is about 5 when the temperature is controlled.
It can be said that the temperature control ripple in the second embodiment, which is about 5 ° C. or less, realizes a ripple equal to or higher than the conventional heater control of the contact temperature sensor.

Further, even during image formation, the control of the output value to the heater is finely switched depending on whether the fixing roller is rotating or stopped, and the presence or absence of the recording material in the nip portion. By switching the control of the output value to the heater finely according to the required power such as during rotation and stop,
More stable and low ripple temperature control can be realized.

(Third Embodiment) Next, a third embodiment of the present invention will be described. Note that the description of the same configuration as the first embodiment or the second embodiment will be omitted.

In the first and second embodiments, the example in which the output to the heater is controlled by the wave number control is shown. However, it is performed by the phase control which controls the phase angle to be energized for each half wave of the power supply waveform. An example will be shown as a third embodiment.

As shown in the current waveform diagram of FIG. 7, the phase angle for energization is controlled for each half-wave of the power supply waveform, and the output to the heater is 0 W as in the first and second embodiments. Two
It was set to be controllable in four stages, equivalent to 50W, 500W and 700W. Further, as in the second embodiment, the temperature detected by the non-contact temperature sensor during image formation is controlled to 500 W when the temperature is 180 ° C. or higher, and 700 W when the temperature is 180 ° C. or lower, and 180 ° C. or higher during standby. The output of 250 W was controlled at 0 W and 180 ° C. or lower.

As a result, the same characteristics as those of the second embodiment can be obtained, and the output to the heater is switched so that the fluctuation range becomes smaller according to the required power, regardless of the method of switching the output to the heater. It was confirmed that the same effect can be obtained with.

That is, in addition to the wave number control and phase control described above, other methods such as time control for controlling the output by the time for which the heater is energized, voltage control for controlling the voltage value applied to both ends of the heater, etc. The same effect can be obtained by controlling the power in multiple steps or continuously, and the present invention is
There is no restriction on the control method of the output to the heater.

In the first to third embodiments, the example in which the output to the heater is controlled in multiple stages has been described, but the output to the heater is controlled steplessly (continuously). It is easily inferred that the same effect can be obtained by using the above method.

Further, the present invention is not limited to the image forming apparatus or the fixing apparatus of the first to third embodiments, but to an image forming apparatus using an electrophotographic technique or an electrostatic recording technique. It is applicable to a fixing device that employs a fixing member such as a heating roll, a heating film, a heating belt, and a heater as a fixing device system.

[0077]

As described above, according to the first invention of the present application, the control means steps the power value from the power source to the heating means in accordance with the temperature detected by the temperature detecting means. Alternatively, since the temperature is continuously changed and controlled, the temperature control ripple of the fixing body is reduced due to the delay of the response at the time of temperature detection of the temperature detecting means for detecting the temperature of the fixing body in a non-contact state. be able to.

According to the second invention of the present application,
Since the control means controls the power value from the power supply to the heating means by changing it stepwise or continuously so as to reduce the fluctuation range based on the temperature detected by the temperature detecting means, it is more effective. Therefore, it is possible to reduce the temperature control ripple of the fixing body due to the delay of the response at the time of the temperature detection of the temperature detecting means that detects the temperature of the fixing body in a non-contact state.

Further, according to the third invention of the present application, the control means changes the power value from the power source to the heating means stepwise or continuously in accordance with the temperature detected by the temperature detection means. And the electric power value from the power source to the heating unit is set in accordance with the operating condition of the fixing device, so that the temperature of the fixing body can be detected more effectively in a non-contact state. It is possible to reduce the temperature control ripple of the fixing member due to the delay in the response of the temperature detecting means during the temperature detection.

According to the fourth invention of the present application,
The control means controls the power value from the power source to the heating means by changing the power value from the power source to the heating means in a stepwise or continuous manner in accordance with the temperature detected by the temperature detecting means, and also during the fixing process and the fixing process. The electric power value from the power supply to the heating unit is set in accordance with the above, so it is possible to more effectively fix the fixing unit due to a delay in the response of the temperature detection unit that detects the temperature of the fixing body in a non-contact state. The temperature control ripple of the body can be reduced.

Further, according to the fifth invention of the present application, the control means changes the power value from the power source to the heating means stepwise or continuously in accordance with the temperature detected by the temperature detection means. In addition, the power value from the power supply to the heating means is set in accordance with the operating condition of the fixing body, so that the temperature of the fixing body can be detected more effectively in a non-contact state. It is possible to reduce the temperature control ripple of the fixing member due to the delay in the response of the temperature detecting means during the temperature detection.

According to the sixth invention of the present application,
The control unit controls the electric power value from the power source to the heating unit by changing it stepwise or continuously in accordance with the temperature detected by the temperature detecting unit and controls the recording material in the fixing device. Since the electric power value from the power supply to the heating unit is set according to the presence or absence of the fixing unit, it is more effective to fix the fixing unit due to a delay in response at the time of temperature detection of the temperature detecting unit that detects the temperature of the fixing unit in a non-contact state. It is possible to reduce the temperature control ripple.

Further, according to the seventh invention of the present application, the control means changes the power value from the power source to the heating means stepwise or continuously in accordance with the temperature detected by the temperature detecting means. Since the temperature of the fixing body is controlled in a non-contact state, the temperature control ripple of the fixing body can be reduced due to the delay of the response at the time of detecting the temperature of the fixing body.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a schematic configuration of a temperature detecting means provided in the fixing device of FIG.

FIG. 3 is a diagram showing a circuit configuration of temperature detecting means provided in the fixing device of FIG.

FIG. 4A shows a power value from a power source during image formation to a heating unit and a contact-type and non-contact-type temperature detection unit by controlling power supplied from a power source of a fixing device to a heating unit in a conventional example. It is a graph showing the relationship with the detected temperature value,
(B) is a contact-type and non-contact-type temperature detection and a power value from the power source to the heating unit during image formation by controlling the power supplied from the power source of the fixing device to the heating unit in the first embodiment of the present invention. It is a graph which shows the relationship with the detection temperature value of a means.

FIG. 5 is a diagram for explaining control of electric power supplied from the power source of the fixing device to the heating unit in the first embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the temperature decrease rate during the response delay period and the power from the power supply to the heating means when the non-contact type temperature detection means according to the first embodiment of the present invention detects 180 ° C. or higher. Is.

FIG. 7 is a diagram for explaining control of electric power supplied from a power source of a fixing device to a heating unit according to a third embodiment of the present invention.

[Explanation of symbols]

1 Fixing unit (fixing device) 2 Fixing roller (fixing body) 4 heaters (heating means) 5 Non-contact temperature sensor (temperature detection means) 8 Infrared absorbing film (radiant heat absorbing member) 9 Infrared detection thermistor element (first temperature detection element) 10 Temperature compensating thermistor element (second temperature detecting element) S recording material

Continued front page    F term (reference) 2G066 AC16 BA09 BB11 BC30 CA15                       CA20                 2H033 AA03 AA18 BA31 BA32 CA04                       CA05 CA07 CA22 CA30 CA32                       CA46 CA47 CA48                 5H323 AA36 BB05 CA08 CB04 DA02                       DB04 FF01 FF10 GG04 GG16                       HH06 KK05 MM04 MM11 MM15

Claims (7)

[Claims] 1. A fixing body, heating means for receiving electric power from a power supply to heat the fixing body, temperature detecting means for detecting the temperature of the fixing body, and the temperature detecting means for detecting the temperature of the fixing body based on the temperature detected by the temperature detecting means. A control unit that controls the power supplied from the power source to the heating unit so as to maintain the fixing member at a predetermined target temperature, and by heating the recording material carrying an unfixed image while contacting the fixing member. A fixing device for fixing the unfixed image on the recording material, wherein the temperature detecting means detects a radiant heat absorbing member for absorbing heat radiated from a fixing body, and a first temperature detecting for detecting a temperature of the radiant heat absorbing member. An element and a second temperature detecting element for detecting an ambient temperature in the vicinity of the radiant heat absorbing member, and a first detected temperature value of the first temperature detecting element and a second detected temperature value of the second temperature detecting element. Compatible with combinations of In the fixing device configured to estimate and detect the surface temperature of the fixing body on the basis of the preset data table, the control unit controls the power supply unit to the heating unit in response to the temperature detected by the temperature detection unit. A fixing device characterized in that the electric power value to the fixing device is controlled by being changed stepwise or continuously. 2. The control means is adapted to control the electric power value from the power source to the heating means by changing it so that the fluctuation range becomes small, based on the temperature detected by the temperature detecting means. The fixing device according to 1. 3. The fixing device according to claim 1, wherein the control means sets an electric power value from the power source to the heating means in correspondence with the operating condition of the fixing device. 4. The control unit sets the electric power value from the power source to the heating unit in correspondence with the fixing process and the fixing process. The fixing device described. 5. The fixing unit according to claim 1, wherein the control unit sets an electric power value from the power source to the heating unit in accordance with an operating state of the fixing body. apparatus. 6. The control unit sets an electric power value from a power source to a heating unit according to the presence or absence of a recording material in the fixing device. The fixing device described. 7. An image forming apparatus for recording an image formed by a series of image forming processes on a recording material, comprising the fixing device according to any one of claims 1 to 6. Image forming apparatus.