JP2003162169A - Fixing device and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device constituted so that the power consumption of the device can be suppressed and also the occurrence of the temperature rise inside the device can be prevented by efficiently heating a fixing body by a heat generating member arranged in the hollow space of the fixing body and prepared for generating and radiating the heat, and to provide an image forming apparatus equipped with the fixing device. <P>SOLUTION: The fixing device is provided with a reflector 4 which is arranged extending in parallel in the axial direction of the fixing roller 1 and prepared for reflecting the heat radiated from the heaters 2 and 3 to the opposite side of the nip part toward the nip part 6 or its vicinity. <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 used in an image forming apparatus such as a copying machine and a printer, and an image forming apparatus including the fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a fixing member and a pressing member that are in pressure contact with each other to form a nip region and rotate, and extend parallel to the axial direction of the fixing member. And a heat generating member that heats the fixing body by heating the recording material carrying the unfixed image in the nip region to fix the unfixed image on the recording material. Is used.

In such a fixing device, for example, a heater, which is a heat generating member, is arranged substantially at the axial position of the fixing roller, which is a fixing member, and the radiant heat from the heater heats the inner peripheral surface to the outer peripheral surface of the fixing roller. The conduction heats the fixing roller from the inside. The detection temperature of the thermistor that detects the surface temperature of the fixing roller is 160 ° C. to 200 ° C.
The drive of the heater is controlled so that the temperature becomes 0 ° C. Introducing a recording material carrying an unfixed image made of toner into a nip region formed by the pressure contact between the temperature-controlled fixing roller and the pressure roller, which is a pressure member that is in pressure contact with the fixing roller. As a result, the toner is melted by heat, and the melted toner is soaked into the recording material by pressure contact with the fixing roller and the pressure roller to fix the unfixed image on the recording material.

[0004]

However, in the above-mentioned conventional fixing device, since the radiant heat from the heater spreads uniformly over the entire inner peripheral surface of the fixing roller as shown in FIG. The outer peripheral surface also becomes uniformly hot. During the fixing process, it is sufficient if only the nip region has a temperature at which the toner can be melted. Therefore, heating the entire circumferential direction of the fixing roller is inefficient and leads to an increase in power consumption. Further, when the entire outer peripheral surface of the fixing roller is at a high temperature, a large amount of heat is dissipated from the fixing roller to the air around it, which causes adverse effects such as temperature rise in the machine.

In view of the above, the present invention efficiently heats the fixing body by a heat generating member that is disposed in the hollow space of the fixing body and radiates heat to suppress the power consumption of the apparatus and increase the temperature inside the apparatus. An object of the present invention is to provide a fixing device capable of preventing the occurrence and an image forming apparatus including the fixing device.

[0006]

According to the present application, the above object is achieved by forming a fixing member and a pressure member that are in pressure contact with each other to form a nip region and rotate, and extend parallel to the axial direction of the fixing member. And a heating member that heats the fixing member by being heated to heat the recording material carrying the unfixed image in the nip region and fix the unfixed image on the recording material. The fixing member has a hollow space, and the heat generating member is arranged in the hollow space to generate heat and radiate heat. The fixing member is formed to extend in parallel to the axial direction of the fixing member. It is achieved by the first aspect of the present invention, which includes a reflecting member that reflects the heat radiated from the heat generating member to the side opposite to the nip region with respect to the heat generating member toward or near the nip region.

According to the present application, the above object can also be achieved by the second invention of the first invention, in which the heat generating member is located closer to the nip region than the axis of the fixing member.

Further, according to the present application, in the first or second invention, the above-mentioned object is such that the reflecting member is located on the side opposite to the nip region with respect to the heat generating member and the surface facing the heat generating member is reflected. It is also achieved by the third invention of making a face.

Further, according to the present application, the above object is achieved in any one of the first to third inventions, wherein the reflecting member is
It is also achieved by the fourth invention in which the surface facing the heat generating member is a concave curved surface.

Further, according to the present application, in any one of the first to fourth inventions, the above-mentioned object is such that the reflecting member is divided into a plurality of members in the axial direction of the fixing member. At least one of the members is a first position that forms a reflecting surface on the same plane as the other member, and a second position that is a position farther to the heat generating member than the first position. It is also achieved by the fifth invention of being switchable and movable.

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

[0012]

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 an electrophotographic laser beam printer 101, which is an example of the image forming apparatus of this embodiment.
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of (hereinafter, simply referred to as printer 101). The image forming apparatus of this embodiment is
Paper feed speed 100 mm / s, print speed 15
Sheet / min printer. The printer 101 is said to form and record an image on a sheet-shaped recording material P according to image information provided from an image information providing device (not shown) such as a host computer provided outside the main body of the printer 101. This is an image forming apparatus in a form in which a series of image forming processes is performed in accordance with a known electrophotographic method.

As shown in FIG. 1, the printer 101 includes a drum-shaped rotatable photoconductor 102 which is a latent image carrier, a developing device 103, and an exposure processing step according to image information from an image information providing device. A laser scanner unit 105 (hereinafter, abbreviated as scanner 105) for forming an electrostatic latent image according to the image information on the outer peripheral surface of the photoconductor 102, and a roll for subjecting the recording material P to a transfer processing step. A rotatable transfer body 106, and a fixing device 107 configured to perform a fixing process on the recording material P that has undergone the transfer process by heating and pressing.

Next, a series of image forming processes in the printer 101 will be described.

First, by pressing a start button or the like (not shown) provided in the main body of the printer 101 to instruct the printer 101 to start a series of image forming processes, the photosensitive member 102 is moved in the direction of arrow K1. When the charging roller 108 to which the specified bias is applied and the photoconductor 102 are brought into sliding contact with each other while being rotationally driven at the specified peripheral speed, the outer peripheral surface of the photoconductor 102 is charged to the specified potential distribution.

Next, the charged portion of the outer peripheral surface of the photoconductor 102 is scanned and exposed by the scanner 105 according to the image information from the image information providing device, and the electrostatic latent image according to the image information is then exposed. After being formed on the above-mentioned portion, the electrostatic latent image is visualized into a visible image by the developer of the developing device 103, and a predetermined number of recording materials P can be accommodated and detached by the main body of the printer 101. A transfer member is transferred from a freely supported cassette 111 to a recording medium P conveyed at a predetermined timing or the like into a space formed between the photoconductor 102 and the transfer member 106 by a rotatable paper feed roller 112 or the like. The visible image is transferred by 106.

Then, the transfer-processed recording material P is subjected to a fixing process by a fixing device 107, and then the printer 10
A sheet is discharged to the outside of the apparatus by the sheet discharge roller 113 rotatably supported by the main body of the first unit, and is stacked on the tray 114 attached to one side surface of the main unit, thereby completing a series of image forming processes. It will be.

FIG. 2 is a schematic sectional view showing a schematic structure of the fixing device 107.

As shown in FIG. 2, the fixing device 107 includes a fixing roller 1 serving as a fixing body, a pressure roller 5 serving as a pressure body, and
The heaters 2 and 3 as heat generating members and the reflection shade 4 as a reflecting member are provided.

The fixing roller 1 has an outer diameter of 30 mm and has two (main and sub) halogen heaters 2 and 3 arranged therein. In this embodiment, the heater 2,
The length 3 is substantially equal to the length of the fixing roller in the axial direction (longitudinal direction).

The pressure roller 5 has the same outer diameter as that of the fixing roller 1 and has a rubber layer having a thickness of 10 mm on the surface. The pressure roller 5 is applied to the fixing roller 1 with a predetermined pressure (about 294 N) by a pressure contact means (not shown). The pressure contact causes the rubber layer to deform and form a nip portion 6 which is a nip region.

Both heaters 2 arranged in the fixing roller 1.
3 is a nip portion 6 from the axis (center) of the fixing roller 1.
And located upstream of the nip portion 6 in the recording material conveyance direction.

The reflection shade 4 faces the upper portions of the heaters 2 and 3 (the surface on the side opposite to the nip portion 6) and has the same length as the heaters 2 and 3 in the longitudinal direction (axial direction of the fixing roller 1). Are arranged so that the positions in the same direction are the same as those of the heaters 2 and 3. The surface of the reflection shade 4 facing the heaters 2 and 3 is a mirror surface having a concave curved surface so as to cover the heaters 2 and 3 as shown in FIG.

In the present embodiment, the fixing roller 1 quickly transfers the radiant heat from the heaters 2 and 3 to the surface of the fixing roller 1, so the thickness t is reduced to 0.3 mm or less, and the rigidity is ensured. The material is iron.

FIG. 3 is a diagram showing the temperature distribution at the phase angle of the fixing roller. In FIG. 3, regarding the phase angle of the fixing roller, the nip portion is 0 degree, the upstream side in the rotation direction of the fixing roller is shown as plus, and the downstream side is shown as minus.

As shown in FIG. 3, since heat is absorbed by the transfer paper at the nip portion of the fixing roller, the surface temperature of the fixing roller at the nip portion upstream end a is 200 ° C., but at the nip portion downstream end b. The temperature drops to 180 ° C.

Conventionally, since the fixing roller is heated by the heater over the entire circumference, the temperature of the fixing roller gradually rises, and the phase angle is −90 ° at 185 ° C. and the phase angle is 180 °.
The temperature rises to 190 ° C. and the phase angle + 90 ° to 195 ° C., and the original temperature of 200 ° C. is recovered at the upstream end a of the nip portion.

On the other hand, in the present embodiment, the temperatures at the nip upstream end a and the nip downstream end b are the same as in the conventional case, but the radiation heat from the heater is provided downstream of the nip downstream end b by the reflection shade. As the heat is blocked, the heat cannot be received and the temperature gradually drops. Then, in the irradiation region (c to a) by the heater and the reflection shade, heat rays are emitted from both the heater and the reflection shade, and the temperature rises rapidly, and the lower temperature 200C is recovered at the upstream end a of the nip portion.

The fixing roller radiates heat from the surface to the surrounding air. The amount of heat radiation increases as the temperature of the heat radiation portion increases. As shown in FIG. 3, comparing the conventional and the present embodiment, the surface temperature of the fixing roller is lower in the present embodiment at all phase angles except the nip portion, and therefore, it can be expected that the heat radiation amount is small. . Since the amount of heat radiation (wasteful thermal energy) is small, it is possible to suppress the power consumption of the heater. Further, since the temperature rise in the copying machine due to the fixing device is moderated, it is possible to suppress the power consumption of the fan or the like as a measure against the temperature rise.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The same components as those of the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 4 is a diagram showing a schematic structure of the fixing device in the present embodiment, and FIG. 5 is a perspective view showing a schematic structure of a reflecting member provided in the fixing device.

In the present embodiment, the heater 22, which is a halogen heater as a heat generating member, is formed inside the fixing roller 21 as a fixing member so as to extend in parallel with the axis of the fixing roller 21. In this embodiment, the fixing roller 2
The length of the heater 22 in the axial direction of 1 is the fixing roller 2
It is almost equal to the length of 1. Further, in the present embodiment, the heater 2
2 is disposed on the nip portion 23 side with respect to the axis of the fixing roller 21. In addition, regarding the heat generating member, the difference between the first embodiment and the present embodiment is that the number of halogen heaters is one.

The halogen heater uniformly heats the fixing roller over the entire longitudinal direction (axial direction). For example, A
When a wide paper such as 3, A4 or the like (hereinafter, referred to as wide paper) is fixed, the paper takes heat from almost the entire area in the longitudinal direction of the fixing roller, but there is no problem. However, for example, narrow width of B5R or the like. When fixing paper (hereinafter referred to as narrow paper),
The temperature of the part where the paper does not pass will rise excessively.

Therefore, in the present embodiment, the reflecting caps 24a and 24b, which are the reflecting members and are arranged so as to face the upper portion of the heater 22 (the surface on the side opposite to the nip portion 23), are divided in the longitudinal direction, and the width is narrow. The reflection shade 24a arranged corresponding to the portion where the paper passes is fixed to the fixing device, and the reflection shade 24b arranged corresponding to the portion where the narrow paper does not pass is the rotating shaft 25.
It is rotatably supported around and can be separated from the heater 22.

The turning of the reflector 24b is performed by moving a lever 26 fixed to the turning shaft 25 by a solenoid (not shown).

When a wide paper such as A4 or A3 is passed through the nip portion 23, the fixing roller 21 needs to be heated uniformly in the entire longitudinal direction, so that the reflection shade 24b is at the position shown by the broken line in FIG. . At this time, since all the radiant heat from the heater 22 is collected in the nip portion 23 and its vicinity, the nip portion 23 of the fixing roller 21 and its vicinity can be efficiently heated over the entire area in the longitudinal direction.

When a narrow paper such as B5R is passed through the nip portion 23, it is necessary to prevent an excessive temperature rise in the non-sheet passing portion of the fixing roller 21, so the reflection shade 24b is located at the position shown by the solid line in FIG. Becomes At this time, the heater 2 reflected by the reflection shade 24b
The radiant heat from 2 does not concentrate on the nip portion 23 and its vicinity and heats the inner peripheral surface of the fixing roller 21 in a wide range. As a result, it is possible to avoid the concentration of heat in the nip portion 23 of the fixing roller 21 and its vicinity, and it is possible to reduce distortion caused by thermal expansion of the fixing roller, and deterioration and deformation of the resin material due to high temperature. .

Therefore, according to the present embodiment, in addition to the effects of the first embodiment described above, excessive temperature rise in the non-sheet passing area in the axial direction of the fixing roller during fixing processing of narrow paper can be prevented. be able to.

[0041]

As described above, according to the first invention of the present application, the heat generating member directly heats the fixing member by the radiant heat from the heat generating member, and the reflecting member changes from the heat generating member. Since the heat radiated to the side opposite to the nip area from the heat generating member is reflected toward the nip area or its vicinity, it is arranged in the hollow space of the fixing member to generate heat and radiate heat. The heat generating member can efficiently heat the fixing body to suppress the power consumption of the apparatus and prevent the temperature rise inside the apparatus.

According to the second invention of the present application,
The heating member directly heats the fixing member on the nip region side of the fixing member by radiant heat from the heating member, and the reflecting member radiates from the heating member to the opposite side of the nip region from the heating member. The heat is reflected toward the nip region or its vicinity, so that the fixing member is more effectively disposed by the heat generating member disposed in the hollow space of the fixing member to generate heat and radiate the heat. It is possible to efficiently heat and suppress the power consumption of the device and prevent the temperature rise in the machine.

Further, according to the third invention of the present application, the heat-generating member directly heats the fixing member by the radiant heat from the heat-generating member, and the reflecting member nips from the heat-generating member more than the heat-generating member. Since the heat radiated to the side opposite to the area is reflected toward the nip area or its vicinity, the fixing is carried out by a heat generating member disposed in the hollow space of the fixing body and radiating heat. It is possible to efficiently heat the body to suppress the power consumption of the device and prevent the temperature rise in the machine.

According to the fourth invention of the present application,
The heat generating member directly heats the fixing member by the radiant heat from the heat generating member, and the reflecting member radiates the heat radiated from the heat generating member to the opposite side of the nip region from the heat generating member to the nip region or its vicinity. The reflecting member is composed of a plurality of members that are divided in the axial direction of the fixing member, and at least one of the plurality of members is on the same surface as the other member. And a second position, which is a position farther to the heat generating member than the first position. While preventing excessive temperature rise of the fixing body, the heat generating member arranged in the hollow space of the fixing body to generate heat and radiate heat efficiently heats the fixing body to suppress power consumption of the apparatus and increase temperature inside the machine. Occurrence can be prevented.

Further, according to the fifth invention of the present application, the heat generating member directly heats the fixing member by the radiant heat from the heat generating member, and the reflecting member makes the nip from the heat generating member more than the heat generating member. Since the heat radiated to the side opposite to the area is reflected toward the nip area or its vicinity, the fixing is carried out by a heat generating member disposed in the hollow space of the fixing body and radiating heat. It is possible to efficiently heat the body to suppress the power consumption of the device and prevent the temperature rise in the machine.

According to the sixth invention of the present application,
The heat generating member directly heats the fixing member by the radiant heat from the heat generating member, and the reflecting member radiates the heat radiated from the heat generating member to the opposite side of the nip region from the heat generating member to the nip region or its vicinity. Since it is designed to be reflected toward the interior of the fixing body, it is efficiently heated by the heat generating member that is disposed in the hollow space of the fixing body and radiates heat to suppress the power consumption of the device and increase the temperature inside the machine. And the like can be prevented.

[Brief description of drawings]

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

FIG. 2 is a schematic cross-sectional view showing a schematic configuration of a fixing device provided in the image forming apparatus of FIG.

FIG. 3 is a diagram showing a temperature distribution in a phase angle in a circumferential direction of a fixing roller according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a schematic configuration of a fixing device according to a second embodiment of the present invention.

5 is a perspective view showing a schematic configuration of a reflecting member included in the fixing device of FIG.

FIG. 6 is a schematic cross-sectional view showing a schematic configuration of a conventional fixing device.

[Explanation of symbols]

1 Fixing Roller (Fixing Body) 2,3 Heater (Heating Member) 4 Reflecting Shade (Reflecting Member) 5 Pressure Roller (Pressurizing Body) 6 Nip Part (Nip Area) 21 Fixing Roller (Fixing Body) 22 Heater (Heating Member) ) 23 nip portion (nip area) 24a, 24b reflective shade (reflective member) 101 electrophotographic laser beam printer (image forming apparatus) 107 fixing device

Claims (6)

[Claims] 1. A fixing member and a pressure member that are in pressure contact with each other to form a nip region and rotate, and a heat generating member that extends parallel to the axial direction of the fixing member and that generates heat to heat the fixing member. A fixing device for fixing the unfixed image to the recording material by heating and pressurizing the recording material carrying the unfixed image in the nip area, wherein the fixing member has a hollow space and the heat generating member is In a fixing device disposed in the hollow space to generate heat and radiate heat, in a fixing member formed to extend parallel to the axial direction of the fixing member, the heat generating member is located on the opposite side of the nip region from the heat generating member. A fixing device comprising a reflecting member for reflecting the radiated heat toward the nip region or its vicinity. 2. The fixing device according to claim 1, wherein the heat generating member is located closer to the nip area than the axis of the fixing member. 3. The fixing device according to claim 1, wherein the reflecting member is located on a side opposite to the nip region with respect to the heat generating member, and a surface facing the heat generating member forms a reflecting surface. 4. The fixing device according to claim 1, wherein a surface of the reflecting member facing the heat generating member is a concave curved surface. 5. The reflecting member is composed of a plurality of members divided in the axial direction of the fixing member, and at least one of the plurality of members forms a reflecting surface on the same surface as the other member. 5. The movable body according to any one of claims 1 to 4, wherein the movable body can be switched to any one of a second position which is a position farther to the heat generating member than the first position. Fixing device. 6. An image forming apparatus for recording an image on a recording material by a series of image forming processes, comprising the fixing device according to any one of claims 1 to 5. Forming equipment.