JPH03228078A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent the offset of various kinds of toner from occurring and to prevent a roller from being damaged by changing condition that a releasing agent coating member is brought into contact with and separated from a heat roller or a pressurizing roller according to the kind of the toner. CONSTITUTION:When a developing device 2 is loaded to the developing device housing position of an image forming device, the contact 5 of a microswitch 4 disposed at a suitable position in the image forming device is turned on by a lever 3 corresponding to the kind of the toner T in the developing device. As the result, the ON signal is inputted to a control unit 11 and the kind of the toner is detected. The action timing and the action time of a releasing agent coating roller 13 being as the releasing agent coating member are controlled to a solenoid 20 from the control unit 11 and the roller 13 is brought into contact with and separated from a fixing roller 7. When the coating roller 13 is brought into contact with the fixing roller 7, fixed press-contact force is given by a coil spring 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for an electrophotographic apparatus using various toners.

[Prior Art] In recent years, due to the miniaturization of devices and fixing properties, it has become common practice to pass a support material supporting an unfixed image between a pair of rotating bodies, and apply heat and pressure to the unfixed image during this passage. It is widely practiced to perform fixing by.

Furthermore, recently, electrostatic recording devices capable of producing full-color or multiple monochromatic color images have been commercialized. These devices either have multiple built-in developing devices to develop the latent image formed on the photosensitive drum, or can be replaced by multiple developing devices to develop full-color or multiple grass-colored images. Images are obtained by developing and heat-fixing using toner.

Each toner has an appropriate fixing temperature depending on its material composition.
Each has been decided.

For example, if we take an electrophotographic device in which the monochromatic color and black developing devices are replaced as separate units and develop a gray image formed on a photosensitive drum, monochromatic color toner produces vivid colors. Therefore, we use a one-component magnetic toner that does not contain magnetic material, and the black toner uses a one-component magnetic toner that contains a magnetic material, which has the characteristics of a relatively simple developing device and easy maintenance. However, in this case, the proper fixing temperature for black toner is higher than that for monochromatic color toner, which is a non-magnetic toner, because it contains a magnetic substance, and the toner resin material and magnetic substance content Depending on the amount, etc., the temperature difference can be several tens of degrees.

For this reason, it has been considered to change the set temperature of the heating rotor depending on the type of toner used.

[Problem to be solved by the invention] However, as mentioned above, when a method of changing the set temperature is adopted, when switching from a high set temperature to a low set temperature, until the temperature drops, There was a problem that it could not be copied.

As another method, as shown in FIG. 6, there is a method in which a felt bat 24 having a heater 21 inside and brought into contact with the fixing roller 22 which contacts the pressure roller 23 is provided, as shown in FIG. Blade 2 brought into contact with similar fixing roller 22
As shown in FIG. 8, a web 26 is brought into contact with a similar fixing roller 22.
A method has been adopted in which a fixed fixing temperature of -1 is set using a forcible cleaning member, such as a method with a cleaning member, and offset toner is forcibly cleaned by a fixing cleaning member. However, in either method, since the fixing roller 22 is pressed against the fixing roller 22 with strong pressure, the fixing roller 22 is easily scratched, and the durability of the fixing roller 22 due to the scratches is poor. Also the 6th
In the case shown in the figure, the life of the felt bat 24 is short because it is a simple felt bat 24, and in the cases of Figures 7 and 8, it is more durable than in Figure @6, but the device is There were problems in that it took up space and was expensive.

The present invention aims to solve the above problems. That is, an object of the present invention is to provide a fixing device that can prevent offset of various toners, does not damage the fixing roller, and has high durability.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a pressure roller in pressure contact with a heat roller, and heats a toner image on an image support sheet held between the rollers. In a fixing device that performs fixing, a release agent is disposed near either the heat roller or the pressure roller to enable contact with and separation from the roller, and has a fibrous layer containing a release agent as an outer layer. A mold release agent application member is provided, and the release agent application member changes the contact and separation conditions depending on the type of toner.

[Function] According to the present invention, the conditions of contact and separation of the release agent coating member with the heat roller or the pressure roller are changed depending on the type of toner, so that offset of various toners can be prevented. In addition, the occurrence of scratches on the roller can be prevented, and high durability can be obtained.

[Embodiment] FIG. 1 is a schematic sectional view of an image forming apparatus that performs electrostatic recording using a fixing device according to a first embodiment of the present invention.

In FIG. 1, a charging device, an exposure device, a developing device, a cleaning device, etc. are provided around a photosensitive drum 1.

Further, the developing device can be replaced with one containing a different type of toner, and by replacing the developing device, it is possible to form an image using toner of a different color.

In order to form an image, a predetermined process is performed through various predetermined devices arranged around the photoreceptor drum 1, and then a latent image formed on the surface of the photoreceptor drum 1 is developed. A developing device 2 is disposed close to the photoreceptor tram 1. The developing device 2 accommodates toner T therein, and a lever 3 is fixed to a suitable position on the outside thereof, for example, in this embodiment, a suitable position on the upper surface of the developing device 2. The position at which this lever 3 is fixed to the upper surface of the developing device 2 varies depending on the type of toner T stored in the developing device. Any position is sufficient as long as the lever 3 can press the contact 5 of the microswitch 4, which is disposed at a suitable position in the apparatus corresponding to each type of toner, when the developing unit is installed in the developing device housing position. Note that the number of microswitches 4 disposed at suitable positions within the apparatus may be one or more depending on the type of toner T that can be used.

This developing device 2 develops the latent image formed on the surface of the photoreceptor drum 1 to form a toner image, and this formed toner image is transferred to a supplied image support material such as paper or the like. The image is then fixed by a heat fixing device 6 disposed within the image forming apparatus.

The fixing device 6 includes a fixing roller rough and a pressure roller 8 that are in contact with the unfixed image, and the fixing roller includes a heater 9 and a thermistor 1o that detects the fixing temperature.

Here, when the developing device 2 is installed in the developing device housing position of the image forming apparatus, a microswitch 4 disposed at a suitable position in the image forming apparatus is activated according to the type of toner T in the developing device. When the lever 3 turns on the contact 5, this ON signal is manually input to the control unit 11, and the type of toner is detected.

The control unit 11 causes the solenoid 2o to control the operation timing and time of the release agent application roller 13, which serves as a release agent application member, to bring it into contact with and away from the fixing roller rough. The coil spring 12 applies a constant pressure when the release agent application roller 13 contacts the fixing roller 7 . The release agent application roller 13 includes a sponge layer 14 that provides elasticity and a felt layer 15 that is impregnated with a release agent.

FIG. 1 shows when the release agent application roller 13 is in contact with the fixing roller rough, and FIG. 2 shows when it is separated.

The inventor has developed a PTFE material with a diameter of 32 m and a wall thickness of 2.5 mm.
(polytetrafluoroethylene) fixing roller (thermal roller) 7, a silicone rubber layer with a thickness of 5 fl 1 m, and an outer layer of P.
F^ (a copolymer of polytetrafluoroethylene resin and perchloroalkoxyethylene resin) with a thickness of 50
30mm diameter coated with μm tubular film
The experiment was conducted using an A3 1/2 size, 20 sheets/min copying machine equipped with a heating type fixing device equipped with a pressure roller 8 and a 900 W heater 9.

The release agent application roller 13 has a thickness of 4m+a on the core metal.
The silicone rubber sponge layer 14 and the surface layer have a thickness of 1.5 mm.
The roller has a diameter of 21 mm and is made of a heat-resistant felt layer 15 with a density of 0.25 g/cm'.

The felt layer 14 is impregnated with about 10 g of silicone oil having a viscosity of 10,000 C5.

The fixing temperature was set at about 180° C., which is a fixing temperature that is good for fixing properties without causing offset of black toner, which is a frequently used one-component magnetic toner.

The contact time of the release agent applying roller 13 was set to about 4 seconds for black toner, which is a -component magnetic toner, and about 12 seconds for monochromatic color toner, which is non-magnetic toner.

A4. Release agent application roller 1 in a mode such as 15 seconds/sheet.
When we looked at the difference in the amount of release agent discharged depending on the contact time in No. 3, we found that it was proportional to the contact time, as shown in Figure 3.

In the case of monochromatic color toner, there is no offset and a good fixing temperature is about 160°C, so the fixed fixing temperature of about 180°C is high, so the contact time of the release agent application roller 13 is lengthened, and the oil is discharged. Offset is prevented by increasing the amount and lengthening the cleaning time.

Under these settings, durability testing was performed using various types of paper and toner, and good results were obtained with no offset even up to 50,000 sheets.

In FIG. 4, the contact time of the release agent application roller 13 is approximately 12 seconds, and the contact pressure is approximately 100 g due to the weight of the release agent application roller 13.
It is a graph showing the amount of oil discharged at A4.15 seconds/sheet when contact is made with pressure of about 400 g and when contact is made with pressure of about 400 g.

Similar to the contact time shown in FIG. 3, the mold release agent is discharged approximately in proportion to the contact pressure.

The release agent application roller 13 is activated by a signal from the control unit 11.
By changing the contact pressure of
You can get the same effect as the horse mackerel shown in the picture.

FIG. 5 shows a second embodiment of the present invention, and is shown in correspondence with FIG.

In the figure, 2a and 2b are developing units, and 3a is a developing unit.

3b is lever 4a 4b is micro switch, 5a
, 5b are contacts, and 16 is a cam drive unit.

That is, the cam drive unit 16 operates the two developing devices 2a.
, 2b, and even with this second embodiment, the same effects as in the first embodiment described above can be obtained.

[Effects of the Invention] As explained above, according to the present invention, the conditions of contact and separation of the release agent coating member with the heat roller or the pressure roller are changed depending on the type of toner. So,
It is possible to prevent various types of toner from being offset, and also to prevent the roller from being scratched, so that it can be used for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an image forming apparatus using the fixing device of the first embodiment of the present invention, the vSz diagram is a partial sectional view for explaining the action of the fixing device of FIG. 1, and FIG. 3 is the experimental results. FIG. 4 is another explanatory diagram, FIG. 5 is a sectional view for explaining the second embodiment of the present invention, and FIG. 6 is an example of the conventional technology. 7 is a sectional view showing another example, and FIG. 8 is a sectional view showing still another example. 1... Photosensitive drums 2.2a, 2b... Developing devices 3.3a, 3b... Lever 4.4a, 4b... Microswitch 5.5a, 5b
... Contact 6 ... Fixing device 7 ... Fixing roller 8 ...
Pressure roller 9... Heater 10... Thermistor 11... Control unit 12... Coil spring 13... Release agent application roller 14... Sponge layer 15... Felt layer 16...・Cam drive unit T...Toner=-=≧ Figure Figure 20: Solenoid Figure 3 Endurance number of sheets [10,000 sheets] Endurance number of sheets [10,000 sheets] Figure Figure Figure Figure

Claims (1)

[Scope of Claims] 1. A fixing device that has a pressure roller in pressure contact with a heat roller and heats and fixes a toner image on an image support sheet sandwiched between the rollers, wherein the heat roller and the pressure roller a release agent coating member disposed near any of the rollers to enable contact with and separation from the roller, and having a fibrous layer containing a release agent as an outer layer; A fixing device characterized in that the application member is adapted to change the conditions of contact and separation depending on the type of toner. 2. The fixing device according to claim 1, wherein the release agent applying member is formed of a roller having a felt layer around a core metal, and rotates due to contact when the roller comes into contact with the member.