JPS6019510B2 - Fusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device that permanently fixes a heat-fusible powder image (hereinafter referred to as a toner image) formed on a support by an electrophotographic copying machine or the like onto the support. It is.

In recent years, electrophotographic copying devices have shown a trend toward higher speeds.

For this reason, fusing methods that supply heat to the toner image support (paper, cloth, polyester film, etc.) from a heating element such as an infrared ray, a hot plate, or a ribbon heater through a poor heat conductor such as air have low thermal efficiency. It is very bad, and as the equipment becomes larger, it is expected that the frequency of use will decrease. Instead of these methods, there is a hot roller fixing method which has a pair of fixing rollers and fixes the toner image on the support by bringing the heated surface into direct contact with the toner image.
It has good thermal efficiency, high safety, and requires small equipment.
It is being used frequently.

Conventionally, in this type of thermal roller fixing device, a release material such as a certain type of RTV (room temperature vulcanization type) silicone rubber is provided on the surface of the fixing roller, or dimethyl silicone oil is provided on the surface of the fixing roller. By supplying an anti-offset liquid such as , methyl phenyl silicone oil, fluorosilicone oil, etc., offset of the toner line from the support to the fixing loaf and wrapping of the support around the roller are prevented.

However, when an RTV silicone rubber roller is used as the fixing roller, the anti-offset performance of the RTV silicone rubber roller deteriorates over time. When used between hemorrhoids, the offset prevention performance of the rubber roller decreased to the point where it was no longer practical.

During long-term use, which is the main cause of deterioration in anti-offset performance, the low molecular weight rubber component or silicone oil in the silicone rubber evaporates due to heating and adheres to the support, reducing the amount of silicone on the surface of the silicone rubber roller. This is due to a decrease in oil concentration. Therefore, in order to obtain a long-life fixing roller that requires less frequent replacement in high-speed copying machines, it is necessary to always use the same amount of silicone oil as is consumed by thermal evaporation, adhesion to the support, and being carried away. Alternatively, it may be necessary to supply it to the surface of the fixing roller as appropriate.

For this reason, in high-speed copying machines, it is common practice to supply an anti-offset liquid such as silicone oil to the surface of the fixing roller. However, when supplying anti-offset liquid to the surface of the fixing roller, it is surprisingly difficult to supply an appropriate amount of anti-offset liquid to the surface of the fixing roller.
Excessive supply will cause the anti-offset liquid to adhere to the support and contaminate the support, resulting in stains of the anti-offset liquid on the support after copying has been completed, which will reduce the quality of the copy or damage the surface of the support. Problems such as poor texture and ink compatibility when adding ink on the support have occurred.

On the other hand, if the supply amount is too small, accidents may occur such as part of the toner image on the support sticking to the surface of the fixing roller or the support getting wrapped around the fixing roller.

In order to eliminate these inconveniences, several supply devices have been proposed that aim to supply an appropriate amount of anti-offset liquid to the surface of the fixing roller.

For example, as shown in FIG. 1, the surface is coated with Teflon or silicone rubber, and the inside is provided with a heating source 7 such as an infrared lamp.
A heat-resistant oil-absorbing member 3 such as Teflon felt or Nomex felt is applied to the surface of the fixing roller 1 having a
Further, by appropriately rotating a pumping roller 5 made of metal or the like, a part of which is immersed in the anti-offset liquid 4 and the other part is in contact with the heat-resistant and oil-absorbing part 3, the anti-offset liquid 4 is heated. A supply device is known that attempts to apply an appropriate amount of anti-offset liquid to the surface of the fixing roller by always keeping the amount of anti-offset liquid supplied to the oil-absorbing member 3 and held by the heat-resistant oil-absorbing member constant. . In the case of the fixing device shown in FIG. 1, the consumption amount ΔM of the offset prevention liquid is related to the number of copies N and the heating time t, and is expressed by a function having two variables as shown in the following equation '1}.

△M=f(N, t) ......{1} Here, if the copying machine is in a state where copying is possible but not being performed (hereinafter referred to as standby), the fixing roller Surface temperature is 150qC~20
Since the high temperature is controlled within a certain range of about 0qC, the anti-offset liquid held in the heat-resistant and oil-absorbing member 3 that is in contact with the surface of the fixing roller gradually oxidizes and evaporates into the atmosphere due to the heat. I'm going to go.

Now, if the consumption amount of offset prevention liquid used for one copy is expressed as △MC, and the consumption amount of offset prevention liquid that thermally oxidizes and evaporates in a thermal atmosphere per unit heating time is expressed as △Ms, then the total consumption amount △M is a function having two variables: the number of copies N and the heating time t.

Therefore, in order to always supply the appropriate amount of anti-offset liquid, it is necessary to change the rotation speed of the pumping roller 5 between continuous copying and intermittent copying, which is extremely difficult to control. Become. Moreover, since the anti-offset liquid is wasted due to thermal evaporation during standby, the cost also increases economically.

Generally, in order to simplify control, the take-up roller is rotated only in proportion to the number of copies, so if paper is continuously fed after a long standby, the anti-offset liquid supply will be insufficient, causing jams and offsets. It becomes easier.

Further, as a supply device for the purpose of supplying an appropriate amount of anti-offset liquid to the surface of the fixing lo-fu, the one shown in FIG. 2 is also known.

That is, one end of the application section 3 of the heat-resistant oil-absorbing material is immersed in the anti-offset liquid, and the other end is appropriately released onto the surface of the fixing roller 1 in order to apply an appropriate amount of the anti-offset liquid to the surface of the fixing roller. It is something to do.

However, in the case of the above-mentioned fixing device, the consumption amount ΔM of the offset prevention liquid is the same as that in Figure 1, and the number of copies N
and heating time t as a variable.

That is, during standby, the applicator 3 gradually absorbs the anti-offset liquid due to capillary action, so for example, after a long pause, the applicator 3 absorbs and retains a large amount of anti-offset liquid, so the applicator 3 is moved to the fixing roller. It is necessary to take measures such as reducing the time for loosening the material onto the surface.

In addition, after a long period of rest, the application member 3 absorbs and retains excess anti-offset liquid (in a saturated state).
When copying the first sheet after a pause, an excessive amount of anti-offset liquid is applied to the fixing roller when the application member contacts the fixing roller, resulting in the disadvantage that oil stains are likely to occur on the first copy paper.

The present invention aims to overcome all of the above-mentioned conventional drawbacks.

Another object of the present invention is to provide an improved fixing device that makes it possible to control the amount of offset prevention liquid consumption ΔM as a function only of the number of copies, ΔM=f(N).

Still another object of the present invention is to provide a fixing device in which the amount of anti-offset liquid consumed does not depend on the heating time t.

Still another object of the present invention is to make it possible to always supply an appropriate amount of anti-offset liquid to the surface of the fixing low-fu with a simple configuration.

Still another object of the present invention is to provide a fixing device that can constantly perform stable fixing by applying the minimum amount of offset prevention liquid necessary without wasting offset prevention liquid. DESCRIPTION OF THE PREFERRED EMBODIMENTS The fixing device of the present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 3 shows one embodiment of the electrophotographic fixing device of the present invention, in which the fixing device is incorporated in a copying machine, and a third
Figure a shows the fixing device during standby, and Figure 3b shows the fixing device during copying.

In Fig. 3, reference numeral 11 denotes a fixing roller with an outer diameter of 4 mm, which is made of a hollow cylinder made of a material with good thermal conductivity such as aluminum or copper, and coated thinly with a durable material 13 such as silicone rubber or Teflon. be.

14 is a pressure roller having an outer diameter of 4 mm and having a core metal 15 coated with relatively thick silicone rubber 16.

As shown in FIG. 3a, both rollers 11 and 14 are stopped in a non-pressure rolling state in which they are in slight contact during standby. The fixing roller 11 is heated by a heat source 17 such as an infrared lamp disposed inside, and the surface temperature of the roller is detected by a temperature detection element 18 such as a thermocouple or thermistor. The temperature is controlled within a predetermined temperature range (around 165°C).

19 is copy paper c on which a toner image has been formed in a copying machine.
This is an entrance guide that guides the machine to the fixing section.

20 is an offset prevention liquid storage tank for storing an offset prevention liquid 21 such as dimethyl silicone oil, methyl phenyl silicone oil, fluorosilicone oil, etc., and 22 is an offset prevention liquid storage tank that stores offset prevention liquid 21 such as dimethyl silicone oil, methylphenyl silicone oil, fluorosilicone oil, etc.; This is an anti-offset liquid holding member that absorbs and holds liquid, and a portion of the holding member 22 is submerged in the anti-offset liquid 21.

23 is an anti-offset liquid supplying member made of a heat-resistant and oil-absorbing material such as Nomex cloth, Teflon cloth, Nomex felt, Teflon felt, etc., which absorbs and retains the anti-offset liquid. Supported.

Reference numeral 25 is made of a heat-resistant rubber such as silicone rubber or fluorine rubber, or a metal roller, and is pressed against the circumferential surface of the fixing roller 11 with an appropriate pressure, and an anti-offset liquid is applied to the surface of the fixing roller 11. This is an applicator roller.

As shown in FIG. 3a, the supply member 23 is lifted by the moving rod 26 during standby, and the holding member 22
and is spaced apart from the application roller 25 and in a non-contact state.

Therefore, during standby, the supply member 23 is separated from the holding member 22 and the application roller 25, so the fixing roller 11
The anti-offset liquid is not applied to the supply member 23, and the anti-offset liquid is not evaporated by heat, so the amount of anti-offset liquid absorbed and held in the supply member 23 does not change and is not affected by standby time. . 27 is the supply member 2
3 is a spring that presses downward (clockwise around the shaft 24'').

Pressurization.

The roller 14 can be moved from a pressure position where it is pressed against the fixing roller 11 to a non-pressure position where it is lightly contacted (or may be separated).
-67335, so the explanation will be omitted. Further, one of the rollers 11 and 14 is coupled to a drive motor, and both rollers 11 and 14 are rotated by the drive of the motor, and the coating roller 26 is driven to rotate. Rollers 11 and 14 due to motor stop during standby
, 26 are stopped. The movable rod 26 is interlocked with the pressure mechanism, and moves downward when the pressure roller 14 is in a pressurized state (that is, during a copying operation).

For example, when the copy paper c reaches a predetermined position in front of the fixing roller 11, the pressure mechanism is operated to apply pressure in response to a signal from the paper detection switch. Therefore, during the copying operation, the downward movement of the movable rod 26 causes the supply section 23 to move downward under the action of the spring 27, and the supply member 23 is moved between the holding member 22 and the application roller as shown in FIG. 3b. 25 and the application roller 25 is rotating.
An anti-offset liquid is applied to the surface of the fixing roller 11.

The application roller 25 not only works to apply an anti-offset liquid onto the surface of the fixing roller and to even it out, but also toner that has been offset on the roller surface due to long-term use is cleaned by the supply member 23 and removed onto the supply member. Since the coating roller is interposed between the supply member 23 and the fixing roller 11, even if the fixing agent adheres to the fixing roller, there is no risk of damaging the fixing roller, and the service life of the fixing roller can be greatly extended.

Furthermore, as described above, after long-term use, the offset prevention liquid supply member becomes dirty with toner attached thereto, which tends to damage the surface of the application roller.

For this reason, the offset prevention liquid supply member 23 is formed into an endless belt shape as shown in FIG. 3, and is gradually moved by a drive mechanism (not shown). If the surface is brought into contact with the coating roller, more stable coating can be achieved. The endless belt does not necessarily need to be moved automatically, and may be moved manually periodically. As described above, in the improved coating device of the present invention, the consumption amount ΔM of the anti-offset liquid depends only on the number of copies;
It can be expressed by the simple formula ΔM=f(N), and since it does not depend on standby time at all, control has become very easy.

Furthermore, since there is no anti-offset liquid that evaporates due to heat during standby, the amount of anti-offset liquid consumed as a whole is small, making it very economical. In addition, by interposing the application roller between the anti-offset liquid supply member and the fixing loaf, there is no fear that the fixing roller will be damaged by toner adhering to the anti-offset liquid supply member during long-term use. This makes it possible to significantly extend the life of the fixing roller.

In addition, the offset prevention liquid supply member is made endless,
By moving the position of the anti-offset liquid application section in contact with the application roller to a new surface before the toner stain becomes serious, it has become possible to perform more stable application.

Reference numerals 30 and 31 denote cleaning felts made of Nomex felt for cleaning excess anti-offset liquid on the roller surface.

Denoted at 32 and 33 are separation claws for separating the copy paper after fixing, and are made of heat-resistant resin such as Teflon, Econol, Besvel, Meldin, or metal.

Reference numerals 34 and 35 denote 9E paper rollers for discharging the copy paper after fixing.

FIG. 4 shows another embodiment, in which parts having similar functions to those of the previous embodiment are designated by the same reference numerals.

FIG. 4a shows a non-coating state, and FIG. 4b shows a coating state, which controls the application of the anti-offset liquid to the fixing roller 11 when the rollers 11 and 14 are in a pressurized state. The support member 24 that supports the endless belt-shaped offset prevention liquid supply member 23 is supported by springs 38, 3.
9, and a solenoid 40 is coupled to the support member 24.

By sending appropriate signals from the copying machine to the solenoid 401, the supply member 23 is moved to the holding member 2 according to the operation of the solenoid.
2 and coating roller 25.

For example, the supply member 2 is synchronized with a copy start signal of a copying machine.
The application amount of the anti-offset liquid can be controlled by moving the supply member 23 into a contact state or by causing the supply member 23 to separate each time a predetermined number of copies (for example, 1 copy) are made. In addition, it is not necessary that the offset prevention liquid supplying member contacts the offset prevention liquid holding member and the application roller at the same time; instead, the timing when the offset prevention liquid supplying member contacts the offset prevention liquid holding member and the application roller is not necessarily the same, and after a certain period of time has passed after the offset prevention liquid supply member contacts the offset prevention liquid holding member, the application roller It may be in contact with the above, or it may be the reverse of the above.

Moreover, the time during which the anti-offset liquid supply section is in contact with the anti-offset liquid holding member and the application roller does not necessarily have to be the same.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a conventional fixing device, FIG. 3 is a schematic configuration diagram of a fixing device to which the present invention is applied, and FIG. 4 is a schematic configuration diagram showing another embodiment of the fixing device of the present invention. It shows. DESCRIPTION OF SYMBOLS 11...Fixing low-fu, 14...Pressure low-fu, 22...Offset prevention liquid holding member, 2
3. ．． ．． ...Offset prevention liquid supply member, 25...
・Application loaf--o beads 1 figure 2 proud 4 (o) bag loaf figure (b) figure 4 (o) figure 4 (b)

Claims (1)

[Scope of Claims] 1. A pair of fixing rollers for fixing a toner image on a support, an application roller for applying an anti-offset liquid to at least one roller of the pair of fixing rollers, and an anti-offset liquid in the anti-offset liquid. an anti-offset liquid holding member that is partially immersed in the liquid and absorbs and holds the anti-offset liquid, and an anti-offset liquid supply member that supplies the anti-offset liquid held in the holding member to the application roller, A fixing device characterized in that the supply member is configured to be brought into contact with and away from the holding member and the application roller, and the supply member is separated from the holding member and the application roller when the anti-offset liquid is not supplied. . 2. In the description of claim 1, the pair of fixing rollers are relatively moved between a pressed position and a non-pressed position, and the offset prevention liquid supply member is moved toward and away from the fixing rollers in accordance with the relative movement of the fixing rollers. A fixing device characterized in that it is configured as follows. 3. The fixing device according to claim 1, wherein the offset prevention liquid supplying member comprises an endless belt that absorbs and holds the offset prevention liquid.