JPH03107979A - Fixing device - Google Patents

Abstract

PURPOSE:To allow the application of an optimum amt. of a mold release agent by providing a pair of fixing rollers which fix the unfixed toner on a transfer material while transporting the toner under a pinching pressure, a means for applying the release agent and a means for adjusting the coating amt. CONSTITUTION:The fixing roller 1 receives rotational driving at the time of fixing and a pressing roller 2 is driven to rotate by this roller. A coating roller 23 which is the means for applying the mold release agent is provided with HTV (heat vulcanized) silicone sponge rubber 23B on a cylindrical arbor 23C and is further provided with an RTV (room temp. vulcanized) silicone rubber layer 23A thereon. An adjusting blade 24 as the means for regulating the coating amt. is in contact with the coating roller 23. The adjusting blade 24 consists of a leaf spring part 24A and a blade part 24B as an adjusting plate mounted to the front end thereof and is mounted to a sectorial gear 26 through a mounting column 25 by means of a screw. The amt. of the oil to be applied on the fixing roller 1 is adjusted to comply with the fixing conditions in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for fixing an unfixed toner image on a transfer material in an electrophotographic process.

[Prior Art] A transfer material having an unfixed toner image is conveyed under pressure by a pair of fixing rollers such as heat rollers while being pressurized and heated to fix the unfixed toner image. At this time, in order to prevent the toner from being offset onto the heat roller, a release agent such as silicone oil is applied to the heat roller. This application is done by a release agent application means that comes into contact with the circumferential surface of the fixing roller, but the amount of application is limited when the maximum amount of toner is placed on a transfer material that is easily offset, such as an OHP sheet. The coating amount is always kept constant. When the transfer material is not passing through, the oil application means is separated from the upper fixing roller and is configured to come into contact with the fixing roller immediately before the transfer material is conveyed to the fixing device.

FIG. 4 shows one conventional example of such a fixing device. In this conventional device, a release agent application roller 23 and a blade 24 for making the amount of application constant are a pump roller 2 that pumps up the release agent from a tank 20 that accommodates the release agent.
A movable plate 7 rotatably supported by a rotating shaft 70 coaxial with 2.
1 is held above.

The rotating plate 71 is biased clockwise by a tension spring 73 to bring the application roller 23 into contact with the fixing roller l above. Further, the single rotation plate 71 can be rotated counterclockwise by a plunger 72 against the tension spring 73, so that the coating roller 23 can be separated from the roller 1.

The plunger 72 is controlled by a control circuit J3, which operates the plunger 72 when the paper is not passing.
The application roller 23 is separated from the upper fixing roller 1.

[Problems to be Solved by the Invention] However, the conventional device as described above has had the following problems.

(2) In the conventional apparatus described above, the fixing roller is always coated with enough oil to prevent offset, even when the combination of transfer material and toner, which is most likely to offset, is used. For example, in the case of a full-color copying machine, OHP paper
Magenta, cyan, yellow, black (hereinafter referred to as M, C
, Y, and 8 are transferred.

For this reason, even in the case of a combination of plain paper with good fixing properties and single-color toner, an unnecessarily large amount of release agent is applied. As a result, in the case of thin paper, etc., too much release agent is applied, resulting in oil streaks, which deteriorate the quality of copies.

(2) The release agent applicator in the conventional device is separated from the fixing roller when the paper is not passing, and is operated to come into contact with the fixing roller in response to a paper passing signal. For this reason, noise and disturbances in the copied image (pitch unevenness) occur due to impact during operation of the release agent application means. Furthermore, failures such as breakage of application roller bearings frequently occur in the release agent application means.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that solves this problem and makes it possible to apply an optimum amount of release agent depending on the type of transfer paper, toner, and amount of toner.

[Means for Solving the Problems] According to the present invention, the above object is to fix unfixed toner on a transfer material while conveying it under pressure.
- Achieved by comprising a pair of fixing rollers and a release agent application means for applying a release agent in contact with the circumferential surface of the fixing roller, and the release agent application means has a coating amount adjustment means. be done.

[Function] In the present invention, the application amount adjusting means is adjusted in accordance with various conditions such as the type of transfer material and the type and amount of toner that affect the optimum application amount of the release agent. As a result, the mold release agent is always applied in an optimum amount matching the conditions described in t. Also,
At this time, since the release agent applying means is always in contact with the fixing roller, no impact is generated even when paper is passing and when paper is not passing.

[Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, l is a fixing roller, and a pressure roller 2 is in pressure contact with this from below. The fixing roller 1 is rotationally driven by means (not shown) during fixing, and the pressure roller 2 is driven by this. Both rollers 1 and 2 each have a built-in heat source 3.4 for heating.

A guide 5 for the transfer material (not shown) is provided on the inlet side (left side in the figure) of both rollers 1 and 2, that is, the transfer material introduction side, and a guide 5 for the recording material is provided on the exit side, that is, the paper ejection side. A separation claw 6.7 is provided to prevent the paper from wrapping around both rollers, and a guide 9 is provided to guide the separation claw to the discharge roller 8.

A web roller 10 for cleaning the roller surface is pressed against the upper surface of the fixing roller l.

Also, a similar web roller 1 is placed on the lower surface of the pressure roller 2.
1 or pressure contact.

Further, the fixing roller l includes pump rollers 21 and 22.
An application roller 23 of a release agent application means, which will be described later, is in contact with the fixing roller l for uniformly applying silicone oil, which is a release agent, pumped up from the tank 20 by the fixing roller l.

The fixing roller l is placed on the aluminum core tube IA, and
Rubber layer IB is provided with a lotus-thick RTV (room temperature vulcanization) silicone rubber or LTV (low temperature vulcanization) silicone rubber.

On the other hand, the pressure roller 2 is placed on the aluminum core tube 2A,
1mm thick HTV (thermal vulcanization) silicone rubber layer 2B
is provided, and its surface is further coated with fluororubber latex. Alternatively, it may be one in which a fluororesin layer is applied on an aluminum core metal tube.

The heat @ 3.4 built into the fixing roller 1 and the pressure roller 2 as described above are connected to the same control circuit 13, and a temperature detection member is placed in contact with the outer surface of the pressure roller 2. In this embodiment, where the temperature is simultaneously controlled based on the detection signal from the barrel thermistor 14, the thermal resistance of the fixing roller l is greater than that of the pressure roller 2.
For example, in the case of the above-mentioned roller, the heat source of both rollers is set to 400 W, and the outer surface temperature of the pressure roller L is set to When the temperature is controlled to 170°C, the outer surface temperature of the fixing roller 1 is maintained at about 155°C. Note that if the relationship of thermal resistance as described above is not particularly taken into consideration, the temperature of the fixing roller needs to be controlled by providing a temperature detection member to prevent excessive temperature rise.

Next, the configuration of the above-mentioned release agent applying means will be explained. The above-mentioned application roller 23, which is a release agent application means, has an HTV silicone sponge rubber 23B provided on a cylindrical core 23G, and an RTV silicone rubber layer 23A having a thickness of I on top of the HTV silicone sponge rubber 23B. An adjustment plate 24 is in contact with the coating roller 23 as a coating amount regulating means. The adjusting blade 24 consists of a leaf spring part 24A and a plate part 24B as an adjusting plate attached to the tip of the leaf spring part 24A, and is attached to the sector gear 26 by a screw on a mounting post 25.

On the other hand, a fan-shaped gear 26 is provided outside the chassis 28 of the fixing unit, and is supported by a rotating shaft 27 whose center of rotation is a point M where the adjustment blade 24 or application roller 23 mentioned above is in contact. A gear 30 provided on a pulse motor 29 including a Tritz circuit meshes with the sector gear 26 . Note that the pulse motor 29 is connected to the control circuit 13. An odometer sensor 31 (connected to the control circuit 13) is provided at the end of the sector gear 26.

The web for cleaning the fixing roller l and pressure roller 2 is
The webs 41 and 42 wound into rolls are fed out and taken up by take-up rollers 43 and 44, respectively.

Further, a cleaning blade 16 is provided in contact with the pressure roller 2 to scrape off oil and dirt left behind by the web roller 11 and collect it in a tank 17.

Furthermore, an image reading unit yItM (not shown) is connected to the control circuit 13 so that the image information read here is calculated by the pixel integration circuit 15 and sent to the control circuit 13 described above. Furthermore, the control circuit 1 also controls the leaf P paper detection means 18 (detects OHP paper having higher transmittance than paper using an optical sensor) provided in the paper feeder (not shown).
Connected to 3.

Next, the operation of the apparatus of this embodiment will be explained.

First, during standby before the fixing operation, the outer surface temperature of the pressure roller 2 is maintained at a predetermined temperature (for example, the above-mentioned 170° C.). Therefore, the fixing roller l is the pressure roller 2.
Although it has a heat source with the same output as , it has a large thermal resistance, so its outer surface temperature is lower than that of the pressure roller 2 (for example, the temperature of the pressure roller is 150°C, compared to 170°C).

Note that even if the power supply to one of the rollers is interrupted to control the power consumption during document exposure of the document reading device (not shown), it is sufficient to control the temperature of both rollers during the above-mentioned standby period. be.

Under such conditions, when a transfer material with unfixed toner is fed between the inner rollers 1 and 2, it is heated and pressed by both the fixing roller 1 and the pressure roller 2 and is fixed.

At that time, a copying device (not shown) including a fixing device of the present invention
Since the power supply of the rollers 1 and 2 has already been turned on, the temperature of the rollers 1 and 2 is controlled to a predetermined temperature by the control circuit 13.

On the other hand, it comes into contact with a release agent application roller 23 that rotates clockwise. The adjustment blade 24 for adjusting the amount of oil applied is connected to a pulse motor 29 via a sector gear 26 and a gear 30.
It rotates under the drive of , and stops at the position where the end of the fan gear 25 is detected by the photosensor 31 . This position is the standard position of the adjustment blade, and the amount of oil applied is the average value. In the initial stage, after this oil application has been carried out for a specified period of time, the adjustment blade 24 rotates clockwise around point M from the standard position until the recording material containing unfixed toner is fed into the fixing device. The tip of the adjustment plate 24 comes into contact with the coating roller 23 over a wide area, and the pump rollers 21, 22 scrape off most of the silicone oil pumped up by the coating roller 23. . This operation is performed by the control circuit 13 via the sector gear 26 and gear 30 and the step motor 29. Further, when increasing the amount of oil applied, the adjustment blade 24 is rotated counterclockwise from the standard position. In this way, it becomes possible to increase or decrease the amount of oil applied, and it becomes possible to adjust the amount of oil applied to be appropriate to the conditions of the recording material, the type of toner, and the amount of toner.

For example, when the above-mentioned image reading device (not shown) is a color image reading device, the image information read by the device is integrated by the pixel amount for each color of M, C, Y, and BK in the pixel integration circuit 15, and the amount of pixels is integrated for each color. is transmitted to the control circuit 13. The control circuit 13 outputs a signal to the step motor 29 to increase the amount of oil applied when the number of pixels is large, and to apply a large amount of oil when the amount of toner is the same but is likely to offset, such as M toner. In response to this signal, the step motor 29 moves the aforementioned adjustment plate 24 from the stock position to a prescribed position.

Further, when a detection signal indicating that the recording material is OHP paper is transmitted to the control circuit from the OHP paper detection means 18 provided in the paper feeding device, the adjustment plate 24 adjusts the amount of oil that is optimal for fixing the OHP paper. Move to adjustment position. In addition, OH
We have explained separately the adjustment of the amount of oil applied using P paper and the pixel integral value, but when copying in color on OHP paper, the optimum amount of oil applied, that is, the position of the adjustment blade, must be determined by taking both conditions into consideration. It can be decided.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment is applied to a device in which oil is pumped up by felt. Note that parts common to those in FIG. 1 are denoted by the same reference numerals, and explanations thereof will be omitted.

In FIG. 2, oil is applied from a tank 50 to an upper roller l by a coating felt 51. In FIG. Coated felt 5
1 is attached to the chassis 53 by screws together with the pressing spring 52.
It is stopped by. The pressing spring 52 is made of a leaf spring, and lightly applies the application felt 51 to the upper roller l to ensure oil application. The coated felt 51 is sandwiched between a shelf 53 fixed to the tank 50 and a curved portion 54A at the - end of the aperture lever 54. The aperture lever 54 is connected to the shaft 5
5, and a clockwise rotational force is applied by a tension coil spring 54G. Furthermore, a cam 56 is in contact with the other end 54B of the aperture lever 54. Cam 5 integrated with fan-shaped gear 58
6 is rotatably supported by a shaft 57, and a fan-shaped gear 58 meshes with a gear 59 integrated with the output shaft of a step motor 60. The step motor 6o is connected to a control circuit 13. The other configurations are the same as in FIG. With the above configuration, the control circuit 13 receives signals from the OHP paper detection means 18 and the pixel integration circuit 15.
calculates the optimum amount of oil to be applied, and according to this, the step motor 60 rotates a specified amount, turns the cam 56, and rotates the aperture lever so that the specified amount of oil is applied to the roller l by the application felt 51. The aperture lever 54 is controlled.

FIG. 3 shows a third embodiment of the invention. As in the first embodiment, the apparatus of this embodiment employs a method in which oil is applied to the upper fixing roller l by an application roller. A portion of the structure different from the first embodiment is shown as (Δ) and will be explained. In FIG. 3, one end of an adjustment plate 70 is in contact with the application roller 23. The adjustment plate 70 is rotatably supported by a cylinder 71 and rotates clockwise to adjust the amount of oil applied to the surface of the application roller 23 to a specified amount.
The slider 74 rotates in response to the driving force from the step motor 76 via the cam 75, and the contact pressure to the application roller 23 is controlled. And this adjustment plate 7
By adjusting the zero contact pressure to a value that suits the fixing conditions, the amount of oil in the application roller can be controlled.

Note that, compared to the first embodiment, the third embodiment is characterized in that the amount of oil applied can be controlled finely, and the second embodiment can be implemented at a lower cost than the other embodiments.

[Effects of the Invention] The present invention can adjust the amount of oil applied to the fixing roller to suit the fixing conditions without separating the release agent coating member from the fixing roller. Also, when using plain paper, the amount of oil applied can be reduced.

■ Oil consumption is reduced.

■ There is no impact caused by attaching and detaching the oil application roller to and from the fixing roller, resulting in the elimination of image blurring.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a device according to a first embodiment of the present invention, Fig. 2 is a schematic diagram of a device of a second embodiment, Fig. 3 is a schematic diagram of a device of a third embodiment, and Fig. 4 is a conventional diagram. FIG. 2 is a schematic configuration diagram of the device. IA...Fixing roller 13--...Control means (control circuit) 23...
・・・・・・Mold release agent application means (mold release agent application roller)

Claims (5)

[Claims] (1) A pair of fixing rollers that fix the unfixed toner on the transfer material while conveying it under pressure, and a release agent applying means that contacts the circumferential surface of the fixing roller and applies a release agent; The fixing device is characterized in that the agent applying means has a coating amount adjusting means. (2) Claim (1) wherein the application amount adjusting means has a control means, and the control means is capable of adjusting the application amount of the release agent upon receiving a signal for determining the type of transfer material. ). (3) The application amount adjusting means has a control means, and the control means is capable of adjusting the application amount of the release agent upon receiving a signal for determining the amount of toner on the transfer material and the type of toner. The fixing device according to claim (1). (4) The fixing device according to claim 3, wherein the toner amount signal is an integrated value of image signals of a digital copying machine. (5) The release agent application means includes an application roller that rotates in contact with the fixing roller, and an adjustment plate that comes into contact with the circumferential surface of the application roller and whose contact angle is variable. term (
The fixing device according to 1).