JP3122691B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly, to a fixing device.
The present invention relates to a fixing device including a fixing roller using an elastic member as a release member.

[0002]

2. Description of the Related Art A typical configuration of a fixing device includes a fixing roller having a built-in heater, and a pressure roller disposed in parallel with the fixing roller and pressed against the fixing roller.
The transfer paper on which the toner image is adhered is passed between the rollers, and the toner image is fixed on the paper by heat and pressure.

In general, a releasing member made of silicon rubber, fluorine material or the like is used for the surface layer of the fixing roller. The thickness of the release member is a few millimeters to several millimeters of a comma, and generally, iron, aluminum, or the like is used for a roller core metal serving as a base of the release member.

[0004]

However, in the above-mentioned prior art, since the release member is thick and the heat conductivity of the roller core is not good, it is difficult to transfer the transfer paper of a small size. In addition, there is a problem that unevenness in temperature distribution (such as a drop in sheet passing temperature and a rise in an end portion) in the axial direction of the fixing roller causes image fixability and a gloss difference in a full-color machine. Further, there is a problem that a difference occurs in the diameter of the fixing roller due to the temperature difference, which causes wrinkles and the like. Also,
A release material is used to improve moldability.
Also overflows from the fixing roller side.

An object of the present invention has been made in view of the above-mentioned circumstances of the prior art, and is intended to prevent unevenness in temperature distribution in the axial direction of the fixing roller,
An object of the present invention is to provide a fixing device in which a release material does not leak from the fixing device.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a fixing roller having a surface covered with an elastic member, a pressure roller for pressing the fixing roller, and a fixing roller .
A heat dissipating member that contacts and cools the roller.
Was fed transfer sheet adhered toner image to the nip between the over la and the pressure roller, the fixing device for fixing the toner image on the paper the transfer, to the heat dissipation member of the fixing roller
The contacting part is made of foaming material or material with excellent water absorption
Therefore, while forming, the release material is collected by the heat dissipation member.
It is characterized by having a function to perform .

[0007]

[0008]

According to the above-mentioned means, when the oval paper size is selected as the transfer paper, the heat radiating member abuts on the surface of the fixing roller which is out of the oval paper size,
Partial heat radiation of the fixing roller is performed. Accordingly, it is possible to prevent the temperature distribution in the axial direction of the fixing roller from being uneven.

Further, by forming the heat radiating member from a material having a foaming property or a water absorbing property, the release material remaining on the surface of the fixing roller is collected by the heat radiating member. Therefore, the release material does not accumulate on the fixing roller, and it is possible to prevent oil dripping and adhesion to the separation claw.

[0010]

FIG. 1 is a front view showing a main part of a first embodiment of a fixing device according to the present invention.

A lower portion of a fixing roller 2 having a built-in heater 1 is pressed into contact with a lower surface of the fixing roller 2 so that a pressure roller 3
The heat dissipating member 4 is disposed above the fixing roller 2 so as to be able to contact and separate therefrom. The fixing roller 2, the pressure roller 3, and the heat radiating member 4 are arranged in parallel in the horizontal direction. On the entrance side of the fixing device, entrance guide members 5a and 5b for introducing the copy paper PP facing the nip portion between the fixing roller 2 and the pressure roller 3 are arranged, and on the exit side of the fixing device. Discharge guides 6a and 6b are provided. In the vicinity of the discharge guide 6a, the fixed recording paper is fixed to the fixing roller 2.
Separating claws 7 are provided for peeling off from the surface.
A pair of paper discharge rollers 8a and 8b are provided in the middle of the paper discharge guides 6a and 6b for sending the recording paper conveyed into the guides to a paper discharge tray (not shown). At the rear end of the paper ejection guide 6a, a charge elimination brush 9 for removing the electric charge charged on the recording paper is attached.

Further, an oil application felt 10 for preventing toner offset is provided around the fixing roller 2, and an oil supply tube 11 for supplying oil (release material) to the oil application felt 10 is provided. The mouth is arranged so as to face the oil-applied felt 10. After the oil-applied felt 10, the fixing roller 2
A blade 12 for cleaning the surface of the fixing roller 2 is provided, and a thermistor 13 for measuring the surface temperature of the fixing roller 2 is provided at a subsequent stage of the blade 12.

FIG. 2 is a perspective view showing the details of the drive mechanism of the heat radiation member 4.

Two roller-shaped heat dissipating members 4 are used, and the width thereof is set to half the length of (A3-A4) or (B4-B5), and the position thereof is also outside the A4 and B5 sizes. Is set. Each of the heat radiating members 4 is
It is rotatably mounted on. One end of a lever 15 having an intermediate fulcrum is fixed to one end of the shaft 14, one end of a spring 16 is attached to the other end, and a movable member of a solenoid 17 is connected to the other end of the spring 16. . A shaft 18 is provided at the fulcrum of the lever 15.
Is attached so that the lever 15 can rotate.

The operation of the above configuration will be described with reference to FIG.

As is well known, in most image forming apparatuses, a paper feed cassette removably mounted on the main body is used in order to cope with different copy sizes and perform automatic paper feed. Normally, a copier for business use is loaded with cassettes of several sizes and is provided with a detecting means for recognizing which paper size cassette is selected, so that one can be designated at the time of copying. ing.

The control of the solenoid 17 is performed based on the determination result of the detection means. For example, if B4 is copied and the designation of the B5 size is changed immediately after the copying of this size is completed, and if the designation change is confirmed (step 301), the paper size is determined (step 302). ). For example, "A4 portrait", "B5 portrait",
When a size such as “A5” is detected, the copy size becomes smaller and the paper does not hit both sides of the fixing roller 2, so that the temperature on both sides rises more than the other parts. Therefore, the solenoid 17 is turned on (step 303), and both sides of the fixing roller 2 are cooled. When the solenoid 17 is turned on, the shaft 18 rotates counterclockwise in the drawing, and the shaft 14 is driven so as to descend, so that each of the heat radiating members 4 is pressed against the upper surface of the fixing roller 2. Thereby, the heat on the outer peripheral surface of the fixing roller 2 is conducted to the heat radiating member 4, and the temperature distribution in the axial direction of the fixing roller 2 can be made uniform, so that the change in the roller diameter can be eliminated. As a result,
Fixing property, uniformity of glossiness, prevention of generation of wrinkles, and the like are achieved. If a certain period of time has passed since the solenoid 17 was turned on (step 304), the temperature equalizing function can be sufficiently achieved, and the solenoid 17 is turned off (step 30).
5). On the other hand, “A3”, “B4”,
If a size such as "A4 landscape" or "B5 landscape" is determined, the solenoid 17 is turned off (step 307), and the process shifts to another process (step 306).

In FIG. 3, the solenoid 17 is controlled based on the cassette detection. However, the solenoid 17 can be controlled by detecting the transport size.

In this case, the size detection sensor 19 is installed in the middle of the transport path from the cassette to the transfer position or in the middle of the transport path from the transfer position to the fixing position as shown in FIG.
On / off control of the solenoid 17 is performed based on the output state. The size detection sensor 19 is installed together with the transport jam sensor 22 on the side of the transport belt 20 (rotated by being transported by the transport roller 21).

The processing corresponding to FIG. 4 will be described with reference to the flowchart of FIG.

When a large-size sheet (for example, A3, B4, etc.) is conveyed, the size detection sensor 19 detects a change in size because its side covers the size detection sensor 19 (step 501). When there is an output signal from the size detection sensor 19, the solenoid 17 is turned off (step 502), and when there is no output signal (meaning small-size paper), the solenoid 17 is turned on (step 504) and continues for a certain period of time. After (Step 505), the power is turned off (Step 506), and the process proceeds to another process (Step 503). On the other hand, when it is determined in step 501 that there is no detection signal, the solenoid 17 is turned off (step 502), and the process proceeds to step 503.

FIG. 6 is a perspective view showing a second embodiment of the present invention. In FIG. 6, the same reference numerals are used for those having the same functions or purposes as those shown in FIGS. 1 and 2, and thus redundant description will be omitted here.

While the heat radiation member 4 is rotated as a driven roller with respect to the fixing roller 2 in the above embodiment, the heat radiation member 4 is forcibly rotated according to the rotation of the fixing roller 2 in this embodiment. There is a feature in the place. For this purpose, a large gear 23 is attached to the shaft end of the fixing roller 2, and a small-diameter gear 24 that can mesh with the gear 23 is attached to the end of the shaft 14. Gear 23 and gear 24
Does not engage when the solenoid 17 is off (non-excited), and only when the solenoid 17 is on, the two gears approach and engage with each other by the rotation of the lever 15. As the fixing roller 2 rotates, the gear 24 rotates, and the heat from the fixing roller 2 is uniformly transmitted to the entire circumference of the heat radiating member 4. Therefore, the possibility that the heat dissipating member 4 scratches the fixing roller 2 is reduced, and the heat dissipating effect of the fixing roller 2 is increased.

FIG. 7 is a perspective view showing a third embodiment of the present invention. In FIG. 7, the same reference numerals are used for those having the same functions or purposes as those of the above-described embodiments, and a duplicate description will be omitted here.

In each of the above embodiments, the same material (fluororesin, silicon dam, etc.) is used for the surface of the fixing roller 2 at any part.
In this embodiment, the heat radiating member 4 is used.
It is characterized by using a foaming material (for example, polyurethane) or a material having excellent water absorbing properties (for example, cloth or paper) in a portion that comes into contact with the material.

The oil (release material) 25 is applied to secure the fixing property of the transfer paper PP and to improve the separation performance. However, when the paper is small, it is applied to both sides of the fixing roller 2. The applied oil does not adhere to the sheet PP and remains on the fixing roller 2 as it is.

As the number of copies of the small-sized paper increases, oil gradually accumulates on the fixing roller 2, and the oil adheres to oil drips and separation claws.

In order to prevent this, in the present embodiment, the heat radiating member 4 itself has an oil collecting function.
That is, if the heat radiating member 4 has a foaming property or a water absorbing property, the oil 26 remaining on the fixing roller 2
It is impregnated or captured on the surface of the heat radiating member 4 and does not remain on the fixing roller 2. As a result, it is possible to prevent oil dripping and adhesion to separation claws and the like.

FIG. 8 is a perspective view showing a fourth embodiment of the present invention. In FIG. 8, the same reference numerals are used for those having the same functions or objects as those of the above-described embodiments, and a duplicate description will be omitted.

In the embodiment shown in FIG. 2, only one solenoid is used. In this embodiment, two solenoids are used so that the pressing force of the heat radiating member 4 can be changed, and the fixing roller 2 is used. The feature is that the contact area between the heat sink and the heat radiating member 4 can be changed. That is, the solenoids 17a, 17b are loaded in parallel to the lever 15 via the springs 16a, 16b, and the springs 16a,
When the urging force of the lever 16 against the lever 15 is 16a> 16b
(May be reversed).

Since the surface portion of the heat radiating member 4 has elasticity, the contact area changes as the pressing force changes. By changing the contact area, the heat radiation condition can be changed. That is, the larger the contact area, the larger the amount of heat radiation, and the smaller the contact area, the smaller the amount of heat radiation. Therefore, it is possible to use such as increasing the contact area for thick paper and decreasing the contact area for thin paper. Alternatively, the contact area may be increased when the number of passed sheets is large, and the contact area may be decreased when the number of sheets is small.

FIG. 9 is a perspective view showing a fifth embodiment of the present invention. In FIG. 9, the same reference numerals are used for the same components as those shown in FIG. 2, and thus the duplicated description will be omitted here.

This embodiment is characterized in that a plurality of heat radiating members 4 in the configuration of FIG. 2 are provided, and a drive system is provided independently for each of the heat radiating members 4. That is, 4a,
The three heat radiating members 4b and 4c are arranged side by side so that the roller portions thereof are alternately arranged, and the levers 15a, 15b and 15c attached to these members are connected to a common shaft 18.
, And the levers 15a, 15b, 15c are connected to solenoids 17a, 17b, 17c via springs 16a, 16b, 16c, respectively.

In this embodiment, the solenoids 17a, 17b and 17c are selected and driven according to the size of the paper PP. For example, when sheets A3 and A4 are sent, only the solenoid 17c is excited. When sheets B4 and B5 are sent, two solenoids 17b and 17c are excited at the same time. When a sheet of paper below the vertical direction is sent, the three solenoids 17a, 17b and 17c are simultaneously excited. As a result, while each of the above-described embodiments can handle only two types of paper sizes, large and small, the present embodiment can support several types of paper sizes.

FIG. 10 is a perspective view showing a sixth embodiment of the present invention. In FIG. 10, the same reference numerals are used for the same components as those shown in FIG. 2, and thus the duplicated description will be omitted.

In this embodiment, in order to enhance the heat radiation effect, a plurality of heat radiation fins 27 are attached to the end of the shaft 14 and these fins 27 are forcibly forced by an electric fan 28. It is intended to be cooled. In addition, 2
Reference numeral 9 denotes a side panel for supporting the shaft of the fixing roller 2.

When the heat radiating member 4 comes into contact with the fixing roller 2, the heat of the fixing roller 2 is transmitted to the surface layer of the heat radiating member 4. However, the heat radiating member 4 has little heat conduction to other members, so that heat is stored. As a result, there is a case where the heat radiation to the fixing roller 2 does not function effectively. Therefore, in this embodiment,
The heat of the heat radiation member 4 is radiated by transmitting the heat of the surface layer to the fins 27 via the shaft 14 and cooling the fins 27 with the electric fan 28.

[0038]

Since the present invention is constituted as described above, the following effects can be obtained.

According to the present invention, the release of the fixing roller
Foamable material or excellent water absorption at the part that contacts the heat member
Since it is formed of a material that has been formed, it is possible to prevent the occurrence of uneven temperature distribution in the axial direction of the fixing roller ,
The release material remaining on the fixing roller is captured by the heat dissipation member
To prevent oil dripping and adhesion to separation nails
it can.

[0040]

[Brief description of the drawings]

FIG. 1 is a front view showing a main part of a first embodiment of a fixing device according to the present invention.

FIG. 2 is a perspective view illustrating details of a drive mechanism of a heat radiation member of FIG. 1;

FIG. 3 is a flowchart showing the operation of the embodiment of FIG. 1;

FIG. 4 is a perspective view showing a sensor arrangement for controlling a solenoid by detecting a transport size.

FIG. 5 is a flowchart showing processing according to the sensor output of the configuration of FIG. 4;

FIG. 6 is a perspective view showing a second embodiment of the present invention.

FIG. 7 is a perspective view showing a third embodiment of the present invention.

FIG. 8 is a perspective view showing a fourth embodiment of the present invention.

FIG. 9 is a perspective view showing a fifth embodiment of the present invention.

FIG. 10 is a perspective view showing a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heater 2 Fixing roller 3 Pressure roller 4 Heat radiating member 5a, 5b Inlet guide member 6a, 6b Discharge guide 10 Oil application felt 11 Oil supply tube 14 Shaft 15,15a, 15b, 15c Lever 16,16a, 16b, 16c Spring 17, 17a, 17b, 17c Solenoid 18 Shaft 19 Size detection sensor 20 Conveying belt 21 Conveying roller 23, 24 Gear 27 Fin 28 Electric fan

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] A fixing roller having a surface covered with an elastic member; a pressure roller pressing against the fixing roller;
A heat dissipating member that contacts and cools the roller.
In a fixing device that passes a transfer sheet having a toner image adhered to a nip portion between a roller and a pressure roller and fixes the toner image on the transfer sheet, a portion of the fixing roller that contacts the heat radiation member is foamed. sex
Made of materials or materials with excellent water absorption
Wherein the heat radiating member has a function of collecting a release material .