JPH07219383A - Fixing device - Google Patents

Abstract

PURPOSE:To shorten a rising time and to obtain an excellent fixed image by heating a pressing roller whose that capacity is larger than that of a fixing roller with a heater having the larger power than that for the fixing roller has. CONSTITUTION:The fixing roller F1 is formed by coating the surface layer part of the hollow core bar F2 with a silicone rubber F3, and a heater F4 such as a halogen lamp is integrated inside. A pressure roller F5 which is held in pressurized contact with and rotary driven by the fixing roller F1 forms a nip with the fixing roller 1, is formed by coating the surface layer part of the hollow core bar F6 with a silicone rubber F7 applied with the fluoride coating for improving the releasing property and has a heater F8 built in in the same way as the fixing roller F1. In the meantime, the pressure roller F5 whose layer thickness of the surface layer silicone rubber is thicker than the fixing roller F1 and the heat capacity is larger, is heated by the heater F8 having the larger output energy than the heater F4 having for the fixing roller F1, and the respective roller F1 and F3 is adjusted to the prescribed temp. by the thermistor and the temp. adjusting circuit.

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 or a printer.

[0002]

2. Description of the Related Art Conventionally, in a fixing device composed of a pair of rotating members provided in an electrophotographic system, in order to secure the fixing property with as little energy as possible, the rotating member side which greatly contributes to the fixing property is lowered. It gives heat capacity and high energy,
In order to make a nip on the other rotating body side, a high heat capacity type is arranged so that even if heated, low energy type is given.

That is, the conventional fixing roller side should be as much as possible.
Both the core metal and the surface layer material are coated with a material having a high thermal conductivity as thinly as possible, and a heat source having a large energy is used so as not to lower the temperature of the surface directly heating the toner. In addition, since the nip is inevitably widened on the pressure roller side, the heat capacity is inevitably large and it is not necessary to guarantee a high temperature because the toner is not directly heated. It only had a heat source.

[0004]

However, in the above-mentioned conventional example, since the temperatures of both rotating bodies are correlated during the copy sequence, it becomes very unstable and causes a problem on the image. In order to prevent the occurrence of this problem, it is preferable that the temperatures of the two rotating bodies are close to each other, but the conventional structure causes a significantly long rise time.

[0005]

SUMMARY OF THE INVENTION According to the present invention for solving the above-mentioned problems, a first fixing rotary member, a first heater for heating the first fixing rotary member, and a nip with the first fixing rotary member are formed. It is characterized in that it has a second fixing rotary member having a larger heat capacity than the fixing rotary member and a second heater for heating the second fixing rotary member and having a larger output energy than the first heater.

[0006]

1 is a sectional view of a full-color electrophotographic apparatus which is an image forming apparatus using a fixing device according to an embodiment of the present invention.

The color electrophotographic apparatus shown in FIG. 1 includes a transfer material conveying system I provided from the right side of the apparatus main body 1 (right side of FIG. 1) to a substantially central portion of the apparatus main body, and the transfer material conveying system I. A latent image forming section II provided in the central portion in the vicinity of the transfer drum 15 constituting the transfer material conveying system I;
The latent image forming section II is roughly divided into developing means, that is, a rotary developing device III.

The transfer material conveying system I has the following structure. First, an opening is formed on the right wall (right side in FIG. 1) of the apparatus main body 1, and transfer material supply trays 2 and 3 that are detachably attached to the opening are provided so as to partially project outside the machine. There is. Paper feed rollers 4 and 5 are disposed substantially directly above the trays 2 and 3, and a transfer drum serving as a transfer means which is rotatable in the direction of arrow A disposed on the left side of the paper feed rollers 4 and 5. The paper feed roller 6 and the paper feed guides 7 and 8 are provided so as to communicate with the paper 15. In the vicinity of the outer peripheral surface of the transfer drum 15, a contact roller 9, a gripper 10, a transfer material separating charger 11 and a separating claw 12 are sequentially arranged from the upstream side to the downstream side in the rotation direction. In addition, the transfer drum 1
A transfer charger 13 and a transfer material separating charger 1 are provided on the inner peripheral side of
4 are provided. A transfer sheet (not shown) made of polyvinylidene fluoride or the like is adhered to a portion of the transfer drum 15 around which the transfer material is wound, and the transfer material is electrostatically adhered and adhered onto the transfer sheet. There is. Conveyance belt means 16 is provided on the upper right side of the transfer drum 15 close to the separation claw 12, and a fixing device 18 is provided at the end (right) end of the conveyance belt means 16 in the transfer material conveyance direction. . A discharge tray 17 that extends to the outside of the apparatus main body 1 and is detachable from the apparatus main body 1 is disposed downstream of the fixing device 18 in the transport direction.

Next, the structure of the latent image forming section II will be described. First, a photosensitive drum 19, which is a latent image carrier that is rotatable in the direction of arrow B in FIG. 1, is arranged with its outer peripheral surface in contact with the outer peripheral surface of the transfer drum 15. Above the photosensitive drum 19 and in the vicinity of the outer peripheral surface thereof, a discharging charger 20, a cleaning means 21, and a primary charger 23 are sequentially arranged from the upstream side to the downstream side in the rotation direction of the photosensitive drum 19, and further. An image exposure unit 24 such as a laser beam scanner for forming an electrostatic latent image on the outer peripheral surface of the photosensitive drum 19,
And an image exposure reflection means 25 such as a mirror.

Finally, the structure of the rotary developing device III is as follows. A rotatable housing (hereinafter referred to as “rotating body”) 26 is disposed at a position facing the outer peripheral surface of the photosensitive drum 19, and four types of developing devices are located at four circumferential positions in the rotating body 26. Mounted on the photosensitive drum 19
The electrostatic latent image formed on the outer peripheral surface of is visualized (that is, developed). The four types of developing devices are a yellow developing device 27Y, a magenta developing device 27M, a cyan developing device 27C and a black developing device 27BK, respectively.

The sequence of the entire image forming apparatus having the above-described configuration will be briefly described first by taking the case of the full color mode as an example. When the photosensitive drum 19 described above rotates in the direction of arrow B in FIG. 1, the photosensitive member on the photosensitive drum 19 is uniformly charged by the primary charger 23. In addition,
In the apparatus of FIG. 1, the operating speed of each part (hereinafter referred to as process speed) is variable from 100 to 300 mm / sec. When the photoconductor is uniformly charged by the primary charger 23, image exposure is performed by the laser light E modulated by the yellow image signal of the document 28, and the photoconductor drum 1 is exposed.
A yellow developing device 27Y in which an electrostatic latent image is formed on the image forming device 9 and which is previously set at the developing position by the rotation of the rotating body 26.
The electrostatic latent image is developed by.

On the other hand, the transfer material conveyed through the paper feed guide 7, the paper feed roller 6, and the paper feed guide 8 is held by the gripper 10 at a predetermined timing and brought into contact with the abutting roller 9. It is electrostatically wound around the transfer drum 15 by the use roller 9 and the opposing electrode. The transfer drum 15 rotates in the direction of arrow A in FIG. 1 in synchronism with the photosensitive drum 19, and the visible image developed by the yellow developing device 27Y is transferred to the outer peripheral surface of the photosensitive drum 19 and the transfer drum 1.
5 is transferred by the transfer charger 13 at a portion in contact with the outer peripheral surface of 5. The transfer drum 15 continues to rotate and is ready for the transfer of the next color (magenta in FIG. 1).

On the other hand, the photosensitive drum 19 is destaticized by the destaticizing charger 20, is cleaned by the cleaning means 21 by the conventionally known blade method, is then recharged by the primary charger 23, and is recharged by the next magenta image signal. Receive image exposure like. The rotary developing device rotates while an electrostatic latent image is formed on the photosensitive drum 19 by the image exposure by the magenta image signal,
The magenta developing device 27M is fixed at the above-mentioned predetermined developing position to perform predetermined magenta development. Subsequently, the above-described processes are performed for cyan and black, respectively, and when the transfer of four colors is completed, the four-color image formed on the transfer material is discharged by the chargers 20 and 14. Then, the gripping of the transfer material by the gripper 10 is released, the transfer material is separated from the transfer drum 15 by the separation claw 12, and the fixing device 18 is fixed by the conveyor belt 16.
Then, a series of full-color print sequences are completed by fixing with heat and pressure, and a desired full-color print image is formed by being discharged by the paper discharge roller 52.

At this time, the fixing operation speed of the fixing device 18 is the process speed of the main body.

Next, a fixing device according to an embodiment of the present invention will be described with reference to FIGS.

Reference numeral 1 denotes a fixing rotator (hereinafter referred to as a fixing roller), which is formed by coating the surface layer of a hollow core metal F2 formed of a metal such as aluminum or iron with a silicone rubber F3. . Further, F4 is a heater such as a halogen lamp and is provided inside the hollow core metal F2 for heating the fixing roller F1.

F5 is a fixing pressure rotator (hereinafter referred to as a pressure roller), which improves releasability on the surface layer of a cored bar F6 formed in the same manner as the hollow cored bar F2. It is formed by covering a silicone rubber F7 coated with fluorine for the purpose. Further, similarly to the fixing roller 1, a heater F8 such as a halogen lamp is provided inside the core metal F6 of the pressure roller F5.

The fixing roller F1 and the pressure roller F5 form a pair, and the pressure roller F5 is configured to be in pressure contact with the fixing roller F1 and driven to rotate.

Further, the fixing roller F1 and the pressure roller F
5 is provided with a cleaner F9 and a blade F10 for removing toner, paper dust and the like adhering to the roller surface, respectively.

The operation of the fixing device will be briefly described with reference to FIG. 2. The transfer material F12 having the formed toner image F11 is transferred to the fixing roller F1 by an inlet guide F13.
And between the pressure roller F5 and the toner image F11.
Is heated and pressed at the nip portion between the fixing roller F1 and the pressure roller F5 and fixed on the transfer material F12. The transfer material F12 after fixing is guided to the outside of the apparatus by a discharge guide F14. At this time, the toner F, paper dust, and the like attached to the surfaces of the rollers F1 and F5 are cleaned by the cleaner F9 and the blade F10.
To eliminate it.

As shown in FIGS. 2 and 3, the fixing roller F1 and the pressure roller F5 are respectively provided with thermistors F15 and F16 for detecting the surface temperature of the fixing roller F1 and the pressure roller F5. Temperature adjusting circuits F17 and F18 for adjusting the electric power supplied to the heaters F4 and F8 provided in the rollers F1 and F5 based on the detected temperature information are respectively installed.

Temperature control is set on the fixing roller F1 and the pressure roller F5, and the thermistor F1 is set.
The temperature adjusting circuits F17 and F18 are configured to adjust the electric power supplied to the heaters F4 and F8 based on the temperature information detected by the heaters F5 and F16, and hold the set temperatures of the rollers F1 and F5. .

As shown in FIG. 2, the temperature adjusting mechanism of the present fixing device has a thermistor 15 and a temperature adjusting circuit 17 for adjusting the electric power supplied to the heater 4 for heating the fixing roller 1. It is configured. On the other hand, adjustment of the electric power supplied to the heater 8 for heating the pressure roller 5 is performed by the thermistor 16 and the temperature adjusting circuit 18.
It is done by.

In this embodiment, the fixing roller F1 is a core metal F.
2, aluminum 5 mm, surface layer silicone gome 1 mm, pressure roller F5 is composed of core metal F6, aluminum 5 mm, surface layer silicone rubber 2 mm. Aluminum and silicone rubber are made of the same material, and the heat capacity of aluminum is much higher than that of silicone rubber. It is a small and negligible range.

Further, the heaters arranged in each are 900 in total.
Up to W, fixing heater F4 300W, pressure heater F
8 and 600W are arranged, and both are temperature-controlled at 170 degreeC.
With this configuration, both fixing and pressure rollers F1 and F5 stand up almost at the same time, and a similar temperature curve is drawn during copying, so that a good image is obtained. As a comparative example, a fixing heater F4 600W, a pressure heater F8 300W, and a fixing heater F4 100W and a pressure heater F8 800W are arranged, but both of them have a rise time of 20%, which causes unstable temperature control during copying. The above uneven gloss occurred.

(Embodiment 2) In this embodiment, the fixing roller F is used.
1 is a core metal F2 aluminum 5 mm, surface silicone rubber 2 m
The pressure roller F5 is composed of a core metal F6 aluminum 5 mm and a surface silicone rubber 1 mm. Aluminum and silicone rubber are made of the same material, and the heat capacity of aluminum is much smaller than that of silicone rubber and can be ignored.

Further, the heaters arranged in each are 900 in total.
Up to W, 600W for fixing heater F4, pressure heater F
8 and 300W are arranged, and both are temperature-controlled at 170 degreeC.
With this configuration, both fixing and pressure rollers F1 and F5 stand up almost at the same time, and a similar temperature curve is drawn during copying, so that a good image is obtained. As a comparative example, a fixing heater F4 300W, a pressure heater F8 600W, a fixing heater F4 900W, and a pressure heater F8 100W were arranged, but both of them had a rise time of 20%, which resulted in unstable temperature control during copying. The above uneven gloss occurred.

(Embodiment 3) In this embodiment, the fixing roller F is used.
1 is a core metal F2 aluminum 5 mm, surface silicone rubber 2.4
mm, the pressure roller F5 is composed of a core metal F6 aluminum 5 mm, and surface silicone rubber 1.8 mm. Aluminum and silicone rubber are made of the same material, and the heat capacity of aluminum is much smaller than that of silicone rubber and can be ignored. .

Further, the heaters arranged in each are capable of heating up to 1200 W at the time of starting up 1200 W and fixing heater F.
No. 4 has 700 W and the pressure heater F8 has 500 W, and both are temperature-controlled at 170 ° C. Furthermore, during copying, each side is turned on / off. With this configuration, both fixing and pressure rollers F1 and F5 stand up almost at the same time, and a similar temperature curve is drawn during copying, so that a good image is obtained. As a comparative example, a fixing heater F4 500 W, a pressure heater F
8 700W, fixing heater F4 800W, and pressure heater F8 100W were arranged, but the rise time was 20% slower in both cases, and unstable temperature control occurred during copying, causing uneven gloss on the image.

[0030]

As described above, according to the present invention, the rise time is short and a good fixed image can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus using a fixing device according to an exemplary embodiment of the present invention.

FIG. 2 is a sectional view of a fixing device according to an exemplary embodiment of the present invention.

FIG. 3 is a heater control circuit diagram.

[Explanation of symbols]

 15 transfer drum 18 fixing device 19 photosensitive drum F1 fixing roller F4 fixing halogen heater F5 pressure roller F8 pressure halogen heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Ishizuka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. A first fixing rotator, a first heater for heating the first fixing rotator, and a second fixing rotator that forms a nip with the first fixing rotator and has a larger heat capacity than the first fixing rotator. ,
A fixing device comprising: a second heater that heats a second fixing rotator and has a larger output energy than the first heater. 2. The fixing device according to claim 1, wherein the first fixing rotator contacts an unfixed image. 3. The apparatus further comprises a first temperature detecting member for detecting the temperature of the first fixing rotary member, and a second temperature detecting member for detecting the temperature of the second fixing rotary member. 3. The fixing device according to claim 1, wherein energization of the first heater is controlled based on a temperature detected by the temperature detection member, and energization of the second heater is controlled based on a detection temperature of the second temperature detection member.