JPH1124489A - Fixing device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of effectively preventing the temperature of a thermal fixing member from lowering and capable of compensating the temperature lowering of the thermal fixing member with good responsiveness by heating the thermal fixing member by means of an outside heating member from an outside. SOLUTION: As to this fixing device having the thermal fixing member having a heat source inside and the outside heating member heating the thermal fixing member from the outside in this image forming device forming an image on an image carrier, and transferring and fixing the image on an image supporting body; when the surface temperature of the thermal fixing member of the fixing device is lowered by the driving of the thermal fixing member or the passing of the image supporting body, the thermal fixing member is heated by the outside heating member, and the thermal fixing member becomes the specified temperature, then the outside heating member stops or reduces the heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine for fixing an image by passing an image support having an unfixed toner image between a pair of fixing members heated at least on one side.
The present invention relates to a fixing device used in an image forming apparatus using an electrophotographic process, such as a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine using this type of electrophotographic process, it is necessary to fix an unfixed toner image formed on an image support to a permanent image. As the fixing method, a solvent fixing method, a pressure fixing method, a heat fixing method and the like are known.

However, the above-mentioned solvent fixing method and pressure fixing method have problems in terms of environmental problems, fixing performance, and the like, and at present, neither of them is widely used.

Therefore, in order to fix the unfixed toner on the image support, a heat fixing method of melting the toner by heating and adhering the toner on the image support has been widely adopted. In this heat fixing method, a pair of fixing members heated at least one side, for example, a heating roll and a pressure roll are brought into contact with each other at a constant pressure, and an image support having an unfixed toner image is passed between the pair of rollers. 2. Description of the Related Art A heat roll method for performing fixing has been conventionally known. This heat roll method is the most widely used fixing method because it has advantages such as lower power consumption and less risk of ignition due to paper jam in the fixing section than other heat fixing methods. is there.

[0005] As a heating roll 100 used in this heating roll type fixing device, for example, as shown in FIG. 20, a surface of a cylindrical cored bar 101 is coated with a heat-resistant elastic body 102 such as silicone rubber. And a resin coated with a heat-resistant resin such as pertetrafluoroethylene (PTFE) or perfluoroalkoxy (PFA).

On the other hand, as the pressure roll 103, silicone rubber is applied to the surface of the cylindrical core 104 so as to have a certain contact width when it comes into pressure contact with the heating roll 100.
One coated with a heat-resistant elastic body 105 such as fluororubber or the above heat-resistant elastic body is made of pertetrafluoroethylene (PTF).
E) and those coated with a heat-resistant resin such as perfluoroalkoxy (PFA) are used.

However, in the case of this fixing device of the heat roll type, since the heat conductivity of the heat-resistant elastic body 101 provided on the surface of the heat roll 100 is poor, a temperature detecting sensor for detecting the surface temperature of the heat roll 100 is used. 109 detects a decrease in the temperature of the surface of the heating roll 100 due to continuous paper passing of the image support 107 carrying the unfixed toner image 106 and a heating lamp 108 provided inside the heating roll 100.
Is turned on, it takes a long time for the heat of the heating lamp 108 to reach the surface of the heating roll 100.
For this reason, there is a problem that the surface temperature of the heating roll 100 continues to decrease until the amount of heat of the heating lamp 108 is transmitted, becomes lower than the minimum fixing guarantee temperature, and a fixing defect may occur. Was.

Therefore, as a measure for preventing this fixing failure, as disclosed in Japanese Patent Application Laid-Open No. 1-52184, an external heating member is disposed so as to be in contact with the surface of the heating roll, and the surface of the heating roll is contacted. There has been proposed a technology for detecting the temperature of the heating roll, turning on the external heating member, and heating the surface of the heating roll.

[0009]

However, the prior art described above has the following problems. That is, according to the technique disclosed in Japanese Patent Application Laid-Open No. 1-52184, an external heating member is disposed in contact with the surface of the heating roll, and the surface of the heating roll is directly heated by the external heating member. Thus, it is possible to prevent the temperature of the heating roll from lowering to some extent,
Separately from the control of the heating source for heating the heating roll, the temperature of the heating roll and the external heating member are detected, and the external heating member is controlled based on the detection result.The surface temperature of the external heating member is It is only controlled constant. Therefore, when the fixing operation is started and the image support is continuously passed, simply heating the surface of the heating roll with an external heating member compensates for a decrease in the surface temperature of the heating roll due to continuous paper passing. However, there was a problem that the responsiveness to the decrease in the surface temperature of the heating roll was poor. That is,
In the case of the technique disclosed in Japanese Patent Application Laid-Open No. 1-52184, the external heating roll intensively heats the surface temperature of the heating roll when the image support is continuously passed. Or it is not possible to switch between regular heating by the heating source inside the heating roll,
There was a problem that the response to the decrease in the surface temperature of the heating roll was poor.

In the case of the technique disclosed in Japanese Patent Application Laid-Open No. 1-52184, since the temperature of the heating roll is controlled to be constant, the fixing process is performed by continuously passing the image support. And, the heating roll can not be heated enough,
There is a problem that the surface temperature of the heating roll itself decreases.

Further, in the case of the technique proposed in Japanese Patent Application Laid-Open No. 1-52184, a heating source for heating an external heating member is required in addition to a heating source for heating a heating roll. There is a problem that the capacity of the commercial power supply generally used in Japan exceeds 100 V / 15 A. In addition, when the heat amounts of the heating source inside the heating roll and the heating source of the external heating member are distributed so as not to exceed the capacity of 100 V / 15 A, it is possible to prevent the temperature drop immediately after the paper passing to some extent. However, when the image support is continuously passed, the heating of the external heating member is insufficient, and the heat supply from the inside of the heating roll is insufficient. There is a problem that the temperature is lower than the minimum fixing assurance temperature and a fixing defect occurs immediately.

In view of the above, the present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to heat a heat fixing member from the outside by an external heating member so that the heat fixing member is heated. It is an object of the present invention to provide a fixing device which can effectively prevent the temperature decrease of the fixing member and can compensate the temperature decrease of the heat fixing member with good responsiveness.

Another object of the present invention is to provide a fixing device having a heat fixing member having a heating source therein and an external heating member capable of heating the heat fixing member from the outside. When the surface temperature of the heat-fixing member of the fixing device is lowered by driving the fixing member, the heat-fixing member is heated by an external heating member to prevent the surface temperature of the heat-fixing member from lowering and to heat the entire fixing device. An object of the present invention is to provide a fixing device which can save energy and maintain good fixing performance by optimizing the amount.

[0014]

According to a first aspect of the present invention, there is provided an image forming apparatus for forming an image on an image carrier, and transferring and fixing the image on an image support. A fixing device having a heat fixing member having a heat source, and an external heating member for externally heating the heat fixing member, wherein the heat fixing member of the fixing device is driven by driving the heat fixing member or passing the image support. When the surface temperature decreases, heat the heat fixing member by the external heating member,
When the temperature of the heat fixing member reaches a predetermined temperature, the heating of the external heating member is stopped or reduced.

According to the first aspect of the present invention,
When the surface temperature of the heat-fixing member of the fixing device is reduced by driving the heat-fixing member or passing through the image support, the heat-fixing member is heated by the external heating member to reach a predetermined temperature. When the surface temperature of the heat-fixing member decreases due to continuous fixing of the image support, the external heating member is caused to generate heat by 100%. By heating the heat-fixing member, it is possible to effectively and responsively prevent the surface temperature of the heat-fixing member from lowering. Further, when the temperature of the heat-fixing member reaches a predetermined temperature, external heating is performed. Since the heating of the member is configured to be stopped or reduced, thereafter, it is possible to maintain the fixing property by heating the heat fixing member by a heating source provided inside the heat fixing member. .

According to a second aspect of the present invention, the heat fixing member is heated by the external heating member by detecting the image formation start signal, and the external heating member is heated when the heat fixing member reaches a predetermined temperature. 2. The fixing device according to claim 1, wherein heating of the member is stopped or reduced.

According to the invention described in claim 2,
Since the heat fixing member is heated by the external heating member by detecting the image forming start signal, it is possible to cope with a temperature decrease of the heat fixing member accompanying the start of the image forming operation in advance, and the external heating with a more responsive property. The heating of the heat fixing member by the member becomes possible.

Further, according to the present invention, the surface temperature of the heat fixing member of the fixing device is reduced by driving the heat fixing member or passing through the image support, and the heat fixing member is connected to an external heating member. 3. The fixing device for an image forming apparatus according to claim 1, wherein the heating by the heating source inside the heating and fixing member is stopped or reduced when the heating is performed.

According to the invention described in claim 3,
When the heat fixing member is heated by an external heating member,
By stopping or reducing the heating by the heating source inside the heating and fixing member, sufficient electric power can be supplied to the external heating member, and the heating and fixing member can be effectively heated by the external heating member.

Further, the invention described in claim 4 is:
4. The fixing device according to claim 3, wherein the amount of heating by a heating source provided inside the heating and fixing member is increased as the heating of the external heating member is stopped or reduced. 5. .

According to the invention described in claim 4,
At the time when the heating by the external heating member of the heating and fixing member is completed, the amount of heating by the heating source provided inside the heating and fixing member is increased in accordance with stopping or reducing the heating of the external heating member, While effectively preventing a rapid decrease in the surface temperature of the heat fixing member, the heat fixing member can be sufficiently heated within a limited electric power range, and good fixability can be maintained.

Further, according to the present invention, when the heating sources provided inside the heat fixing member and the external heating member are simultaneously turned on, the sum of the heating amounts of the respective heating sources is equal to or less than a set value. The fixing device of the image forming apparatus according to claim 1, wherein the fixing device is set so as to be as follows.

According to the invention described in claim 5,
When the heating sources provided inside the heat fixing member and the external heating member are simultaneously turned on, the total heating amount of each heating source is set to be equal to or less than a set value, so that the surface temperature of the heat fixing member decreases. By optimizing the heating amount of the entire fixing device, it is possible to provide a fixing device that can save energy and maintain good fixing performance within a limited power range.

According to a sixth aspect of the present invention, the lighting timing of each heating source is adjusted so that the heating sources provided inside the heating fixing member and the inside of the external heating member are not simultaneously turned on. A fixing device for an image forming apparatus according to claim 1.

According to the invention described in claim 6,
The lighting timing of each heating source was adjusted so that the heating sources provided inside the heating fixing member and the inside of the external heating member did not light simultaneously, so that the heating fixing member and the external heating member were controlled within a limited power range. It is possible to provide a fixing device that can heat the members most effectively and maintain good fixing performance.

Further, the invention according to claim 7 is characterized in that the heating amount of a heating source provided inside the heat fixing member and the inside of the external heating member is controlled by elapse of a predetermined time. Item 7. A fixing device for an image forming apparatus according to any one of Items 1 to 6.

According to the invention described in claim 7,
By controlling the amount of heating of the heating source provided inside the heat fixing member and the inside of the external heating member over a predetermined time, the heating of the heat fixing member and the external heating member is controlled by a simple control means. It becomes possible.

The invention according to claim 8 is the fixing device of the image forming apparatus according to any one of claims 1 to 7, wherein the external heating member is a rotating body. However, besides the rotating body,
It may be of a fixed type.

Further, the invention according to claim 9 is the fixing device of the image forming apparatus according to claim 8, wherein the rotating body is an endless belt.

According to the invention described in claim 9,
By making the rotating body an endless belt, the contact area between the heat fixing member and the external heating member formed of the endless belt can be increased, so that the heat fixing member can be more effectively heated. it can.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIG. 2 shows an embodiment of a fixing device used in the image forming apparatus according to the present invention.

An image forming apparatus such as an electrophotographic copying machine or a printer forms an image on an image carrier such as a photosensitive drum, and transfers and fixes the image on an image support to form an image. It is configured to be. In this image forming apparatus, a fixing device is used to fix an unfixed toner image on an image support.

In this fixing device, as shown in FIG. 2, at least one of a pair of fixing members having a heating source, for example, a heating roll 1 and a pressure roll 2 are pressed against each other, and the nip of the pair of rolls 1 and 2 is pressed. By passing the image support 4 having the unfixed toner image 3 between the copies, the unfixed toner image 3 is fixed on the image support 4 by heat and pressure to form a permanent image. However, the fixing device is not limited to this, and a belt nip type device that performs fixing by pressing an endless belt against a heating roll may be used.

Heating roll 1 used in the fixing device
For example, as shown in FIG. 2, the surface of a cylindrical cored bar 5 made of metal such as aluminum or stainless steel is coated with a heat-resistant elastic body 6 such as silicone rubber, or pertetrafluoroethylene (PTFE) or the like. One coated with a heat-resistant resin such as perfluoroalkoxy (PFA) is used.

On the other hand, as the pressure roll 2, the surface of the cylindrical metal core 7 made of metal such as aluminum or stainless steel is formed so that a certain nip width is formed when the pressure roll 2 comes into pressure contact with the heating roll 1. One coated with a heat-resistant elastic body 8 such as rubber or fluororubber, or one coated with a heat-resistant resin such as pertetrafluoroethylene (PTFE) or perfluoroalkoxy (PFA) on the heat-resistant elastic body 8 is used. Can be

The heating roll 1 is heated by a heating lamp 9 as a heating source disposed inside.
As the heating lamp 9, for example, a lamp having a power of 600 W is used. However, the heating lamp 9 is not limited to this, and a lamp having another value may be used. The surface temperature of the heating roll 1 is detected by a temperature detection sensor 10 arranged to be in contact with the surface of the heating roll 1. In addition,
As a heating source provided in the fixing device, as shown in FIG. 2, in addition to a case where the heating source is provided in the heating roll 1, a heating source provided in the pressure roll 2, or a heating source provided in both the heating roll 1 and the pressure roll 2. It may be provided.

An external heating roll 11 as an external heating member for externally heating the heating roll 1 is provided on the surface of the heating roll 1 so as to be in contact therewith.
The external heating roll 11 has a cylindrical member 12 made of a metal such as aluminum, iron, copper, and stainless steel.
It is set to 30 mm, and has a smaller diameter than the heating roll 1 whose outer diameter is set to 30 to 100 mm. A release layer (heat-resistant resin such as PTFE or PFA) (not shown) having a thickness of several to several tens of micrometers may be provided on the outer peripheral surface of the external heating roll 11. Since the thermal conductivity of the external heating roll 11 is reduced, it is desirable that no release layer is provided, or even if it is provided, it is made as thin as possible. The external heating roll 11 is rotatably supported by the rotation of the heating roll 1 by contacting the surface of the heating roll 1.

Further, the external heating roll 11 is heated by a heating lamp 14 as a heating source disposed inside. As the heating lamp 14, for example, 40
Although a value of 0 W is used, the value is not limited to this, and a value of another value may of course be used. The surface temperature of the external heating roll 11 is detected by a temperature detection sensor 15 arranged so as to be in contact with the surface of the external heating roll 11.

As the external heating member, as shown in FIGS.
Or a belt type 17 may be used.

Further, on the surface of the heating roll 1, in addition to the above, a peeling claw 18 for peeling the image carrier 4 such as a transfer sheet from the heating roll 1 is provided. On the other hand, the image support 4 on which the unfixed toner image 3 is formed is
9 passes through a nip formed by the heating roll 1 and the pressing roll 2 to fix a toner image on the image support 4.

In this embodiment, when the surface temperature of the heat fixing member of the fixing device is lowered by driving the heat fixing member or passing the image support, the heat fixing member is heated by the external heating member. When the temperature of the heat fixing member reaches a predetermined temperature, the heating of the external heating member is stopped or reduced.

FIG. 6 is a block diagram showing the temperature control means of the fixing device according to this embodiment for performing such control.

In the drawing, 1 is a heating roll, 9 is a heating lamp arranged inside the heating roll 1, 11 is an external heating roll, and 14 is a heating lamp arranged inside the external heating roll 11. Things. Also,
Reference numeral 10 denotes a temperature detection sensor for detecting the surface temperature of the heating roll 1, and reference numeral 15 denotes a temperature detection sensor for detecting the surface temperature of the external heating roll 11.

The temperature detection sensors 10 and 15 are connected to a CPU 20 as a control means, and the CPU 20 is connected to SSRs (Solid State Relays) 2 connected to the heating lamps 9 and 14, respectively.
The heating lamps 9 and 14 are controlled via the heating lamps 9 and 14 to control the power supply to the heating lamps 9 and 14 and to stop the heating. For example, control is performed such as to keep the surface temperature at a predetermined value.

In the fixing device according to this embodiment having the above structure, the temperature of the heat fixing member is effectively prevented from lowering by heating the heat fixing member from the outside by an external heating member as follows. As a matter of course, it is possible to compensate for a decrease in the temperature of the heat fixing member with good responsiveness.

Further, in the fixing device according to this embodiment, as described below, a heating fixing member having a heating source inside and a fixing device having an external heating member capable of heating the fixing member from outside are used as follows. When the surface temperature of the heat fixing member of the fixing device is reduced by driving the paper or the heat fixing member, the heat fixing member is heated by an external heating member to prevent the surface temperature of the heat fixing member from lowering. By optimizing the heating amount of the entire fixing device, it is possible to save energy and maintain good fixing performance.

That is, in the above fixing device, FIG.
As shown in FIG. 1, when the power supply of the image forming apparatus is turned on, the temperature detection sensor 10 provided on the surface of the heating roll 1 starts to detect the surface temperature of the heating roll 1 (step 101). As shown in FIG. 1, the detection of the surface temperature of the external heating roll 11 is started by the temperature detection sensor 15 provided on the surface of the external heating roll 11 (Step 102). And the heating roll 1
It is determined whether or not the surface temperature of the heating roll 1 has reached the fixing temperature T1 (for example, 150 ° C.) (step 103).
If the surface temperature of the heating roll 1 is not higher than the fixing temperature T1,
The heating lamp 9 provided inside is turned on (step 10).
4) The lighting of the heating lamp 9 is continued until the fixing temperature T1 is reached. Further, the external heating roll 11 is also a heating roll 1.
Similarly to the above, it is determined whether or not the surface temperature of the external heating roll 11 has reached a predetermined temperature t1 (for example, 160 ° C.) (Step 105), and if the surface temperature of the external heating roll 11 is equal to or lower than the predetermined temperature t1. If there is, the heating lamp 14 provided inside the external heating roll 11 is turned on (Step 10).
6) The lighting of the heating lamp 14 is continued until the temperature reaches the predetermined temperature t1.

The heating roll 1 or the external heating roll 1
1 reaches the target temperature T1 or t1, FIG.
As shown in (1), the heating lamp 9 or 14 of the heating roll 1 or the external heating roll 11 which has reached the target temperature T1 or t1 is turned off (Steps 107 and 108), and the surface temperatures of the heating roll 1 and the external heating roll 11 are both reduced. Both target temperature T1
And whether or not t1 has been reached (step 10).
9). If the surface temperature of either the heating roll 1 or the external heating roll 11 has not reached the target temperature T1 or t1, the heating of the heating roll 1 or the external heating roll 11 not having reached the target temperature T1 or t1. Lamp 9
Further, the lamp 14 is turned on (steps 104 and 106), and is heated until the target temperature T1 or t1 is reached.

When the surface temperatures of the heating roll 1 and the external heating roll 11 both reach the target temperatures T1 and t1, the CPU 20 determines that copying is possible, and outputs a copy enabling signal (step 110). State
It is determined whether a copy start signal has been input (step 111).

Here, before the copy start signal is input, the heating roll 1 and the external heating roll 11
It is determined whether the surface temperature of the heating roll 1 or the external heating roll 11 is lower than the control temperature T1 (step 112).
Alternatively, if the temperature is not shorter than t1, the heating lamp 9 or 14 is turned off (step 113). If the surface temperature of the heating roll 1 or the external heating roll 11 is higher than the control temperature T1 or t1, the heating lamp 9 or 14 is turned off. Is turned on (step 14), and the heating roll 1 or the external heating roll 11 is turned on.
Is maintained at constant control temperatures T1 and t1, as shown in FIG.

If it is determined that the copy start signal has been input (step 11), the fixing device turns off the heating lamp 9 provided in the heating roll 1 as shown in FIG. 1 (step 11). 115), the heating lamp 14 provided inside the external heating roll 11 is turned on (Step 116), so that the heating roll 1 is heated only by the heating lamp 14 provided inside the external heating roll 11. next,
When the surface temperature of the heating roll 1 reaches the set temperature T2 (for example, 14
0 ° C.) (step 11).
7) When the temperature of the heating roll 1 reaches the set temperature T2,
Conversely, the heating lamp 14 provided inside the external heating roll 11 is turned off (step 118), and the heating lamp 9 provided inside the heating roll 1 is turned on (step 1).
19) Then, as shown in FIG. 1, the temperature control of the heating roll 1 is continued only by the heating lamp 9 provided inside the heating roll 1. When the copying operation is completed (Step 120), the heating lamps 9 and 14 are turned on (Steps 121 and 122) so that the surface temperatures of the two rolls 1 and 11 become the target temperatures T1 and t1, respectively. Control is started at each of the target temperatures T1 and t1 as described above.

As described above, in the above embodiment, when the surface temperature of the heating roll 1 is lowered by the start of the fixing process of the heating roll 1, the heating roll 1 is heated by the external heating roll 11, and The heating roll 1 is at a predetermined temperature T
When the surface temperature of the heating roll 1 decreases due to continuous fixing of the image support 4, the heating of the external heating roll 11 is stopped. By heating the heating roll 1 by generating 100% heat, the surface temperature of the heating roll 1 is reduced.
As shown in FIG. 8, it is possible to effectively and responsively prevent the heating of the external heating roll 11 when the surface temperature of the heating roll 1 reaches a predetermined temperature T2. After that, the heating roll 9 is heated by the heating lamp 9 provided inside the heating roll 1 to maintain the fixing property.

Further, by detecting the copy start signal, the heating roll 1 is heated by the external heating roll 11,
When the heating roll 1 reaches a predetermined temperature T2, the heating of the external heating roll 11 is stopped, and the heating roll 1 is heated by the external heating roll 11 by detecting a copy start signal. It is possible to cope with a decrease in the temperature of the heating roll 1 accompanying the start in advance, and it becomes possible to heat the heating roll 1 by the external heating roll 11 having more responsiveness.

Further, the heating roll 1 is connected to the external heating roll 1
By stopping the heating by the heating lamp 9 inside the heating roll 1 during heating by the heating roll 1, sufficient electric power can be supplied to the external heating roll 11. Effective heating becomes possible.

Further, when the heating lamps 9 and 14 provided inside the heating roll 1 and the inside of the external heating roll 11 are simultaneously turned on, the sum of the heating amounts of the heating lamps 9 and 14 is set to a set value (for example, 1000 W). By setting as follows, the surface temperature of the heating roll 1 can be prevented from lowering, and the amount of heating of the entire fixing device can be optimized. Thus, energy can be saved within a limited power range and energy can be saved. And a fixing device capable of maintaining good fixing performance.

Second Embodiment FIG. 8 shows a second embodiment of the present invention. The same parts as those in the above-described embodiment are denoted by the same reference numerals. The turning on and off of each heating lamp was controlled by the temperature of the roll reaching a predetermined value T2. However, in this embodiment, by providing a plurality of the predetermined values and controlling the electric energy of each heating lamp, The heating roll surface temperature can be further optimized.

That is, in the second embodiment, the basic control is the same as that in the first embodiment. However, when it is determined that the copy start signal is inputted as shown in step 211 in FIG. The fixing device sets the power supplied to the heating lamp 9 provided in the heating roll 1 to 0% (step 215), and reduces the power supplied to the heating lamp 14 provided in the external heating roll 11 to 100%. (Step 216), the heating roll 1 is heated only by the heating lamp 14 provided inside the external heating roll 11. Next, as shown in FIG. 9, it is determined whether or not the surface temperature of the heating roll 1 has decreased to a set temperature T3 (for example, 145 ° C.) (Step 217), and the temperature of the heating roll 1 is reduced to the set temperature T3. When it reaches, this time the external heating roll 11
The power supplied to the heating lamp 14 provided inside the heating roll is set to 50% (step 218), and the power supplied to the heating lamp 9 provided inside the heating roll 1 is also set to 50% (step 219). As shown in FIG.
It is determined whether or not the surface temperature has decreased to the set temperature T2 (for example, 140 ° C.) (step 220). When the temperature of the heating roll 1 reaches the set temperature T2, the surface of the heating roll 1 is installed inside the external heating roll 11 next. The power supplied to the heating lamp 14 is set to 0% (step 221), and the heating roll 1
The power supplied to the heating lamp 9 provided inside the heating roll 1 is set to 100% (step 222), and the temperature control of the heating roll 1 is continued only by the heating lamp 9 provided inside the heating roll 1. When the copying operation is completed (step 22
3) the surface temperature of the two rolls 1 and 11 is the target temperature T1
Then, the respective heating lamps 9 and 14 are turned on so as to reach t1 and t1 (steps 224 and 225), and control is started at the target temperatures T1 and t1 as shown in step 209.

As described above, in the second embodiment, FIG.
As shown in (1), when the surface temperature of the heating roll 1 is lowered by the start of fixing to the image support 4, the heating roll 1 is heated by the external heating roll 11.
When the temperature reaches the predetermined temperature T3, T2, the external heating roll 1
Since the heating of the heating roller 14 of the external heating roll 11 is initially reduced when the surface temperature of the heating roll 1 decreases due to the continuous fixing of the image support 4, the heating lamp 14 of the external heating roll 11 is initially set. The heating roll 1 is heated by generating 100% of heat, and as the amount of heat of the heating lamp 9 inside the heating roll 1 gradually reaches the surface of the heating roll 1, the heating lamp 14 of the external heating roll 11 is turned on by 50% power. so,
By heating the heating lamp 9 of the heating roll 1 with 50% electric power, the heating roll 1 can be efficiently heated from the outside and the inside of the heating roll 1. When the temperature reaches T2, the surface temperature of the heating roll 1 is further reduced by heating the heating lamp 14 of the external heating roll 11 with 0% and the heating lamp 9 inside the heating roll 1 with 100% power. Can be effectively and responsively prevented,
Since the heating of the external heating member is stopped when the temperature of the heating roller 1 reaches the predetermined temperature T2, the heating roller 9 is provided by the heating lamp 9 provided inside the heating roller 1 thereafter. Can be heated to maintain the fixing property.

Further, as the heating of the external heating roll 11 is reduced, the amount of heating by the heating lamp 9 provided inside the heating roll 1 is increased, so that the surface temperature of the heating roll 1 sharply decreases. While effectively preventing
The heating roll 1 can be sufficiently heated within a limited power range, and good fixing properties can be maintained.

Other structures and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

Third Embodiment FIG. 10 shows a third embodiment of the present invention. The same parts as those in the above embodiment are denoted by the same reference numerals. Lighting and extinguishing of each heating lamp are controlled when the temperature of the roll reaches a predetermined value T2. However, in the third embodiment, the electric energy of each heating lamp is gradually changed without providing a predetermined value. Is configured.

That is, in the third embodiment, the basic control is the same as that in the first embodiment. However, when it is determined that the copy start signal is inputted as shown in step 311 in FIG. The fixing device turns off the heating lamp 9 provided inside the heating roll 1 (step 31).
5), a heating lamp 14 provided inside the external heating roll 11
Is turned on (step 316), the heating roll 1 is heated only by the heating lamp 14 provided inside the external heating roll 11. Thereafter, as shown in FIG. 11, the surface temperature of the heating roll 1 is set to a set temperature T2 (for example, 140 ° C.).
° C) is determined (step 31).
7) When the temperature of the heating roll 1 reaches the set temperature T2,
This time, the heating lamp 14 installed inside the external heating roll 11
The power supplied to the heating roll 9 is gradually reduced to 0% (step 318), and the power supplied to the heating lamp 9 provided in the heating roll 1 is gradually increased to 100% (step 319). The temperature control of the heating roll 1 is continued only by the heating lamp 9 installed in the heating roll 1. When the copying operation is completed (step 32)
0), as in the above embodiment, the two rolls 1, 11
Are turned on (steps 321 and 32) so that the surface temperature of
2) As shown in step 309, control is started at each of the target temperatures T1 and t1.

Here, as a method for gradually changing the electric energy of each of the heating lamps 9 and 14, a method based on a voltage change,
A phase control method, a cycle steal method, or the like is used. Of these, the method of changing the heating lamp lighting time (including cycle steel) has a simple structure and can be implemented at low cost (FIGS. 12 and 13).
At this time, as a method of changing the heating lamp lighting time, as shown in FIG. 12, even if the cycle of the AC voltage applied to the heating lamps 9 and 14 of the heating roll 1 and the external heating roll 11 is controlled to be thinned out. As shown in FIG. 13, the energizing time of the AC voltage applied to the heating lamps 9 and 14 of the heating roll 1 and the external heating roll 11 may be controlled, for example, in seconds.

As described above, the heating lamps 9 and 14 are gradually increased.
By changing the electric energy of the external heating roll 11
Of the heating roll 1 and the heating by the heating lamp 9 inside the heating roll 1 can be used to heat the heating roll 1, and the surface temperature of the heating roll 1 can be reduced more rapidly. The heating roller 1 can be sufficiently heated within a limited range of electric power while preventing the occurrence of the electric power, so that good fixability can be maintained.

Other configurations and operations are the same as those of the above-described embodiment, and the description thereof is omitted.

Fourth Embodiment FIG. 14 shows a fourth embodiment of the present invention. The same parts as those of the above embodiment are denoted by the same reference numerals and described. Although the heating amount of the heating source provided inside the heating fixing member and the inside of the external heating member is controlled by turning on or off the light according to the surface temperature of the heating fixing member, in the fourth embodiment, The amount of heating of the heating source provided inside the heat fixing member and the inside of the external heating member is controlled by elapse of a predetermined time.

That is, in the fourth embodiment, the basic control is the same as that of the first embodiment as shown in FIG. 14, but when it is determined that a copy start signal has been input (step 411). The fixing device turns off the heating lamp 9 provided inside the heating roll 1 (step 415), and turns on the heating lamp 14 provided inside the external heating roll 11 (step 416). The heating roll 1 is heated only by the heating lamp 14 provided inside the heating roll 11. Next, by the CPU 20,
It is determined whether TM seconds have elapsed since the start of copying (step 417), and as shown in FIG.
When M seconds have elapsed, the external heating roll 11
The heating lamp 14 provided inside the heating roll 1 is turned off (step 418), and the heating lamp 9 provided inside the heating roll 1 is turned off.
Is turned on (step 419).
, The temperature control of the heating roll 1 is continued only by the heating lamp 9 provided therein. When the copying operation is completed (Step 420), the heating lamps 9 and 14 are turned on (Steps 421 and 422) so that the surface temperatures of the two rolls 1 and 11 become the target temperatures T1 and t1, respectively. Control is started at each of the target temperatures T1 and t1 as described above. The predetermined time TM is determined by measuring the time required to reach the power change temperature shown in the first to third embodiments by a test and determining the predetermined time TM.

As described above, in the above embodiment, the heating amount of the heating lamps 9 and 14 provided inside the heating roll 1 and the inside of the external heating roll 11 is controlled by the passage of a predetermined time, so that the heating roll is controlled. 1 and the external heating roll 11 can be controlled by simple control means.

Other configurations and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

Fifth Embodiment FIG. 16 shows a fifth embodiment of the present invention. The same parts as those of the above embodiment are denoted by the same reference numerals and described. The turning on and off of each heating lamp was controlled by the temperature of the roll reaching a predetermined value T2. However, in this embodiment, a plurality of the predetermined values are provided, and the electric energy of each heating lamp is set to a predetermined time. Based on this control, the heating roll surface temperature can be further optimized.

That is, in the fifth embodiment, the basic control is the same as that in the second embodiment. However, when it is determined that the copy start signal is inputted as shown in step 511 of FIG. The fixing device sets the power supplied to the heating lamp 9 provided in the heating roll 1 to 0% (Step 515) and reduces the power supplied to the heating lamp 14 provided in the external heating roll 11 to 100%. % (Step 516), the heating roll 1 is heated only by the heating lamp 14 provided inside the external heating roll 11. Next, as shown in FIG.
It is determined whether or not one second has elapsed (step 517). If TM1 has elapsed after the start of copying, the power supplied to the heating lamp 14 provided inside the external heating roll 11 is reduced by five.
0% (step 518), and the heating roll 1
The power supplied to the heating lamp 9 provided inside the printer is also set to 50% (step 519). Thereafter, as shown in FIG. 17, it is determined whether TM2 seconds have elapsed since the start of copying (step 520). If TM2 seconds have elapsed after the start of copying, the power supplied to the heating lamp 14 provided inside the external heating roll 11 is set to 0% (step 52).
1) The power supplied to the heating lamp 9 provided inside the heating roll 1 is set to 100% (step 522).
, The temperature control of the heating roll 1 is continued only by the heating lamp 9 provided therein. When the copying operation is completed (step 523), the heating lamps 9 and 14 are turned on (steps 524 and 525) so that the surface temperatures of the two rolls 1 and 11 become the target temperatures T1 and t1, respectively. Control is started at each of the target temperatures T1 and t1 as described above.

As described above, also in the fifth embodiment, the heating amount of the heating lamps 9 and 14 provided inside the heating roll 1 and the inside of the external heating roll 11 is controlled by elapse of a predetermined time, so that the heating is performed. The heating of the roll 1 and the external heating roll 11 can be controlled by simple control means.

The other configuration and operation are the same as those of the above-described embodiment, and the description thereof is omitted.

Sixth Embodiment FIG. 18 shows a sixth embodiment of the present invention. The same parts as those in the above embodiment are denoted by the same reference numerals. The turning on and off of each heating lamp is controlled by the temperature of the roll reaching the predetermined value T2. However, in the sixth embodiment, the predetermined value is not provided, and the electric energy of each heating lamp is changed by the lapse of the predetermined time. Is configured to be gradually changed based on the

That is, in the sixth embodiment, the basic control is the same as that of the above-described embodiment. However, when it is determined that the copy start signal is inputted as shown in step 611 of FIG. The fixing device turns off the heating lamp 9 provided inside the heating roll 1 (step 61).
5), a heating lamp 14 provided inside the external heating roll 11
Is turned on (step 616), the heating roll 1 is heated only by the heating lamp 14 provided inside the external heating roll 11. Thereafter, as shown in FIG. 19, it is determined whether or not TM seconds have elapsed since the start of the copying (step 617). When TM seconds have elapsed since the start of the copying, the heating lamp provided inside the external heating roll 11 is now turned on. 14 is gradually reduced to 0% (step 6).
18) The power supplied to the heating lamp 9 provided inside the heating roll 1 is gradually increased to 100% (step 61).
9) Finally, the temperature control of the heating roll 1 is continued only by the heating lamp 9 provided in the heating roll 1. When the copying operation is completed (step 620), the heating lamps 9 and 14 are turned on so that the surface temperatures of the two rolls 1 and 11 become the target temperatures T1 and t1, similarly to the above embodiment (step 621). , 622), control is started at each of the target temperatures T1 and t1, as shown in step 609.

As described above, also in the sixth embodiment, the heating amount of the heating lamps 9 and 14 provided inside the heating roll 1 and the inside of the external heating roll 11 is controlled by elapse of a predetermined time, so that the heating is performed. The heating of the roll 1 and the external heating roll 11 can be controlled by simple control means.

The other configuration and operation are the same as those of the above-described embodiment, and the description thereof will be omitted.

In the above embodiment, the electric energy of each heating lamp is controlled by the set value of the heating roll temperature, or the power is controlled by the time from the start of copying without using the heating roll temperature. It is a matter of course that the same result can be obtained depending on the time when the image support reaches the fixing device.

In the above embodiment, the power when the heating lamp provided inside the external heating roll is turned on and the heating lamp provided inside the heating roll is turned off is reduced by 10%.
0% and 0%, however, the present invention is not limited to the power ratio, and the power when turning on the heating lamp provided in the external heating roll is 80% and the power is provided in the heating roll. Of course, it is not necessary to completely turn on and off the heating lamp, such as 20% of the power when the heating lamp is turned off. In addition,
As shown in FIG. 12 or 13, by controlling the lighting of the heating lamp provided inside the external heating roll and the heating lamp provided inside the heating roll, the heating lamp is provided inside the heating fixing member and inside the external heating member. It is possible to adjust the lighting timing of each heating source so that the heating sources that are not turned on at the same time.

[0081]

As described above, according to the present invention, the temperature of the heat fixing member can be effectively prevented from lowering by heating the heat fixing member from the outside by the external heating member. That is, it is possible to provide a fixing device capable of compensating for a decrease in the temperature of the heat fixing member with good responsiveness.

Further, according to the present invention, in a fixing device having a heating fixing member having a heating source inside and an external heating member capable of heating the heating fixing member from the outside, paper feeding or driving of the heating fixing member is performed. When the surface temperature of the heat-fixing member of the fixing device decreases, the heat-fixing member is heated by an external heating member to prevent the surface temperature of the heat-fixing member from lowering and to optimize the heating amount of the entire fixing device. By doing so, it is possible to provide a fixing device that can save energy and maintain good fixing performance.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an operation showing an embodiment of a fixing device of an image forming apparatus according to the present invention.

FIG. 2 is a configuration diagram illustrating an embodiment of a fixing device of the image forming apparatus according to the present invention.

FIG. 3 is a configuration diagram illustrating an embodiment of a fixing device of the image forming apparatus according to the present invention.

FIG. 4 is a configuration diagram showing a modification of the embodiment of the fixing device of the image forming apparatus according to the present invention.

FIG. 5 is a configuration diagram showing a modification of the embodiment of the fixing device of the image forming apparatus according to the present invention.

FIG. 6 is a block diagram showing a control unit in one embodiment of the fixing device of the image forming apparatus according to the present invention.

FIG. 7 is a flowchart showing an operation of the fixing device of the image forming apparatus according to the embodiment of the present invention;

FIG. 8 is a flowchart illustrating an operation of the fixing device of the image forming apparatus according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating an operation of the fixing device of the image forming apparatus according to the second embodiment of the present invention;

FIG. 10 is a flowchart showing the operation of the fixing device of the image forming apparatus according to the third embodiment of the present invention.

FIG. 11 is an explanatory diagram illustrating an operation of the fixing device of the image forming apparatus according to the third embodiment of the present invention;

FIG. 12 is an explanatory diagram illustrating a control example of a fixing device according to a third embodiment of the present invention.

FIG. 13 is an explanatory diagram illustrating a control example of a fixing device according to a third embodiment of the present invention.

FIG. 14 is a flowchart illustrating an operation of the fixing device of the image forming apparatus according to the fourth embodiment of the present invention.

FIG. 15 is an explanatory diagram illustrating an operation of the fixing device of the image forming apparatus according to the fourth embodiment of the present invention;

FIG. 16 is a flowchart showing an operation of the fixing device of the image forming apparatus according to the fifth embodiment of the present invention.

FIG. 17 is an explanatory diagram illustrating an operation of the fixing device of the image forming apparatus according to the fifth embodiment of the present invention.

FIG. 18 is a flowchart showing an operation of the fixing device of the image forming apparatus according to the sixth embodiment of the present invention.

FIG. 19 is an explanatory diagram illustrating an operation of the fixing device of the image forming apparatus according to the sixth embodiment of the present invention.

FIG. 20 is a configuration diagram illustrating a fixing device of a conventional image forming apparatus.

[Explanation of symbols]

1 heating roll, 2 pressure roll, 9 heating lamp, 1
0 temperature detection sensor, 11 external heating roll, 15 temperature detection sensor, 14 heating lamp, 20 CPU.

Claims (9)

[Claims] An image forming apparatus that forms an image on an image carrier, and transfers and fixes the image on an image support,
A heat fixing member having a heat source inside, a fixing device having an external heating member for heating the heat fixing member from the outside, by driving the heat fixing member or passing through the image support,
When the surface temperature of the heat-fixing member of the fixing device decreases, the heat-fixing member is heated by the external heating member, and when the heat-fixing member reaches a predetermined temperature, the heating of the external heating member is stopped or reduced. A fixing device for an image forming apparatus. 2. An image forming start signal is detected, whereby the heating and fixing member is heated by an external heating member, and when the heating and fixing member reaches a predetermined temperature, the heating or heating of the external heating member is stopped or reduced. The fixing device for an image forming apparatus according to claim 1, wherein: 3. The heating / fixing member of the fixing device, when driven by the heating / fixing member or passing through the image support, lowers the surface temperature of the heating / fixing member. 3. The fixing device for an image forming apparatus according to claim 1, wherein heating by a heating source inside the member is stopped or reduced. 4. The image forming apparatus according to claim 3, wherein the amount of heating by a heating source provided inside the heat fixing member is increased as the heating of the external heating member is stopped or reduced. Fixing device. 5. When the heating sources provided inside the heat fixing member and the external heating member are turned on at the same time, the total heating amount of each heating source is set to be equal to or less than a set value. The fixing device of the image forming apparatus according to claim 1. 6. The lighting timing of each heating source is adjusted so that heating sources provided inside the heat fixing member and inside the external heating member are not simultaneously turned on. And a fixing device for the image forming apparatus. 7. The apparatus according to claim 1, wherein the amount of heating of a heating source provided inside the heat fixing member and inside the external heating member is controlled by elapse of a predetermined time. A fixing device of an image forming apparatus. 8. The fixing device according to claim 1, wherein the external heating member is a rotating body. 9. The fixing device for an image forming apparatus according to claim 8, wherein said rotating body is an endless belt.