JPS5990876A - Fixing device - Google Patents

Abstract

PURPOSE:To reduce extemely an offset toner and to realize a stable fixing performance by making a cleaning member and a conductive needle-like member press-contact with each other in the longitudinal direction of the surface of a rotary roll. CONSTITUTION:A conductive needle-like member 8 is provided in the longitudinal direction of a pressure roll, prevents electrostatic charge of the pressure roll 2, prevents an offset and prevents paper from winding itself round. When the member 8 is made to press-contact with the roll 2, the tip part is made to press-contact with the roll from the tip side face of the member 8, seeing in the rotating direction of the roll 2. As a result, even if a fine powder toner passes through a cleaning member, it is caught by the tip side face of the member 8, therefore, the tip part is always clean, the destaticizing capacity does not drop at all, electrostatic charge of the roll 2 is always eliminated, an offset is prevented, and the fixation can be executed with a high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to means for preventing toner offset or paper wrapping by removing static electricity in a deposition device.

Conventionally, it has been known to eliminate electricity from the fixing roller in order to prevent copy paper from wrapping.

Static elimination methods include: 1. Mixing conductive substances such as carbon and metal powder into the necessary rollers to lower the resistance of the rollers. ■A charger is installed near the roller to remove static electricity from the roller using corona.

■Put the static elimination brush in contact with the roller. AC bias is further applied to (2) and (2). This is already known.

Also, as a method of preventing toner offset to the roller, (1) Apply a bias having the same polarity as the toner on the roller on the side that comes into contact with the toner image surface of the copy paper. ■It has been proposed that the material of the roller that comes into contact with the toner image surface of the copy paper be selected from a frictional charging material that is charged to the same polarity as the toner.

However, (2) significantly deteriorates the mechanical properties and mold release properties of the roller and is not practical. ＠The device is large and complicated, and spark discharge is likely to occur near the fixing device due to the high voltage applied.
It cannot be said that this method is excellent in terms of reliability. (2) When the static elimination brush becomes dirty, the static elimination efficiency decreases rapidly, changes over time are large, and there is no durability. (2) In addition to (2), spark discharge is extremely likely to occur due to contamination. For ■, it is difficult to apply bias; for example, applying it to the core metal has little effect;
If it is applied from the surface with a static eliminating brush or the like, spark discharge is likely to occur and reliability is low. ■Similar to the material, there is currently no material that is effective while maintaining various physical properties.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned drawbacks, to provide a fixing device which has a simple configuration, minimizes offset toner, and has stable fixing performance over a long period of time.

The present invention will be explained below with reference to the drawings. FIG. 1 is a side view of an embodiment of the present invention, showing a heat fixing device. A heating roller 1 has a heating heater 3 such as a halogen heater inside, and rotates in the direction of the arrow in response to a driving force from a driving motor (not shown). ko is a pressure roller with a built-in heater Ja for low heating, which is in pressure contact with a heating roller and rotates as a result.

This heating roller 1 is made of a metal material such as aluminum, stainless steel, or steel (with a layer of heat-resistant mold-releasing resin such as tetrafluoroethylene resin on the outer peripheral surface of the hollow roller core).

~goμ thick. The pressure roller is rotatably supported by a bearing (not shown). This roller λ is pressed against the heating roller by a known pressure means at least during fixing, and has a relatively thick elastic material such as silicone rubber, furan rubber, or fluorosilicone rubber on the outer peripheral surface of a metal roller core. , this configuration has the purpose of securing a protrusion in the pressure contact area with the heating roller.

A temperature sensing element such as a thermistor or thermocouple is provided in contact with the outer peripheral surface of the heating roller l, and the output of the heater 3 is controlled by the detection signal of the sensor, and the temperature of the outer peripheral surface of the heating roller l is adjusted to adjust the temperature of the toner. The image is maintained at the melting temperature. ja, jb
is a separating claw for reliably separating the fixed copy paper from the heating roller. Reference numeral 6 denotes a cleaning device for removing foreign matter such as offset toner and paper dust adhering to the surface of the heating roller from the surface of the roller, which uses a cleaning web 6a made of heat-resistant nonwoven fabric. The cleaning web 6a is still in contact with the heating roller by an elastic pressing roller 6c, and is moved from the supply roller 6b by a take-up roller 6d so as to change its contact position little by little, so that a new surface always comes into contact with the heating roller. 2 is a guide plate that guides the copy paper P carrying the toner image T toward the heating roller I. In order to prevent offset and paper wrapping, the conductive needle member is provided in the longitudinal direction of the pressure roller to prevent charging of the pressure roller. In addition, the method of bringing the conductive needle-like member into contact with the roller is as follows: When viewed in the direction of rotation of the roller, the side surface of the end of the conductive needle-like member is brought into contact with the roller, and then the tip is brought into contact with the roller. Very good results can be obtained if they are brought into contact with each other.

This is because even if fine powder toner were to pass through the cleaning member, it would be collected on the side surface of the tip of the conductive needle-like member, so the tip would always be clean and the static elimination ability would not deteriorate at all. The electrically conductive needle member holder consists of a grounded electrically conductive support ffa, which is commonly used, and a large number of needle members g fixed to the support. Needle member gb
is preferably made of flexible conductive fibers such as metal fibers or carbon fibers, and the diameter of the fibers is within iooμ. A cleaning member t is made of heat-resistant felt such as Nomex or Teflon and is brought into contact with the heating roller in the longitudinal direction upstream of the conductive needle member g when viewed in the rotational direction of the pressure roller.

Figure 1 (e-), Figure 1 (1)), and Figure 2 (C) are
FIG. 7 shows a side view of another embodiment in which a ribbed needle-like member and a cleaning member are combined. In FIG. 2 (F3), a blade-shaped cleaning member made of silicone rubber, furan rubber, fluorosilicone, etc. is embedded together with a conductive needle-like member on a conductive support IO. Figure 1 (1)) shows the blade-like cleaning member 13 and the conductive needle-like member i4I as the U-shaped metal member l! I had a sandwich. Figure 1 (C)
This is a cleaning member in which one end of the conductive rubber blade member/V, which vulcanizes the rubber of No. 6, is embedded in the rubber blade. Can be used on both the front and back sides.

Further, the conductive needle-like member on the side not in contact with the roller plays the role of eliminating static electricity during peeling between the copy paper and the roller in the peelable area. By integrally molding the cleaning member and the conductive needle-like member as described above, it is possible to install the static eliminating member near the nip portion on the paper ejection side (described later), which has the highest offset prevention effect (described later). In addition, since the amount of dirt adhering to the pressure roller a is extremely small, a simple cleaning member is sufficient.
In addition to felt, we also use roller-shaped cleaning members made of silicone rubber, fluorocarbon rubber, or rubber or metal mixed with metal fillers, and blade-like cleaning materials such as silicone rubber, fluorocarbon rubber, fluorosilicone rubber, etc. Just use it.

The effects of the present invention and other embodiments will be shown below through experiments.

(1) Experimental conditions Heating roller/...thickness 7I+! 30μm thick PII'A coated outer diameter & own roller pressure roller on +1 aluminum core...thick wall on stainless steel hollow core! Gourd's HTV silicone rubber coated roller with outer diameter of 60flIII...Total pressure: 60Kg Copy...-A,? Size: 23 sheets per minute Roller speed: Core θ / El e C manuscript: Image area, 2A'% (relatively high ner consumption) Environmental conditions: Moisture: 60 inches, temperature: 23 ℃ static electricity removal measurement...
・Performed using a coulomb meter Q as shown in Figure 3.

(2) The results are shown in Figures 1 and 5. In Fig. 1, the horizontal axis represents the number of durable copies, and the vertical axis represents the amount of charge removal in μC. In other words, A for the number of copies
It shows the amount of charge removal ΔQ in copying 3 patterns/sheet.

Curve (a) shows the conventional case where the tip of a conductive needle electrode is simply brought into contact with a pressure roller, and no cleaning member is provided upstream thereof. The amount of charge removal begins to decrease rapidly after approximately 3θθO sheets, and the toner offset increases after approximately 6000 sheets, and the feed speed θ of the web 6a decreases.
,! ;wn/min, the cleaning could not be completed and the toner accumulated on the web 6a and fell off. Furthermore, the toner that has passed through the web 6a adheres to the copy paper, resulting in a significant deterioration in copy quality.

Curve (b) shows the case where the tip of the conductive needle-like member is placed 3 steps away from the roller, the static elimination effect is small from the beginning, the offset prevention effect is small, and the feed rate of the web 6a is 0. A:tr
ys/min, toner adhered to the copy paper due to poor cleaning and significantly degraded the copy quality, but it was possible to prevent the paper from wrapping around the pressure roller.

Curve (C) is an example of the present invention, and even after copying / 00,000 sheets, the static elimination ability hardly decreased compared to the initial stage. Even after copying 10θ, 000 sheets, the feed speed of the web 6a is 0. ! Even at rmrr/min, only enough offset was generated to allow sufficient cleaning, and the copy paper was not stained by the offset toner at all.

Curve (d) is a dotted line indicating the amount of charge removal of −C//4tμC,
This shows the limits of the effective range for offset prevention.

Curve (e) is a dotted line showing the amount of charge removal at -θ 7pc, and shows the limit of preventing the paper from wrapping around the pressure roller 2. However, the above values are values for this configuration and are not absolute values.

Figure S shows the degree of action when the position of the conductive needle-like member g is changed, Figure S (a) shows the position of the conductive needle-like member g, and Figure S (1)) shows the effect. is a line diagram,
The horizontal axis represents the distance downstream from the nip between the heating roller 1 and the pressure roller, and the vertical axis represents the amount of static electricity removed. According to FIG. 5(1)), it is most effective to provide the conductive needle-like member g near the downstream side of the nip in the longitudinal direction of the roller. Comparing the amount of offset to the fixing roller, if the amount of offset when there is no conductive needle member is l, at point (A) / /j' ~ /7/ /θ, (
D) At point //ko~//Hiro, at point <a> //2~//3,
(to) point, it decreased to l/co~i7q.

As mentioned above, the initial static elimination effect is obtained by the conventional static elimination method in which a conductive needle-shaped static elimination member is used in contact with a pressure roller without the aid of an equivalent cleaning means as shown in Figure DA (a). is good, but as the number of copies increases, the tip of the conductive needle-like static eliminator gets dirty with toner, paper dust, and other foreign matter, and the static neutralization ability rapidly decreases, making it impossible to clean or replace it 7 times for every 5θ00 sheets. However, according to the present invention, as shown in Figure (C), a cleaning member is provided immediately upstream of the point where the conductive needle-like static eliminating member is in contact with the pressure roller. The pressure roller maintains a very good initial state of static neutralization, the electrostatic repulsion from the pressure roller side is reduced, the offset of toner to the heating roller is extremely reduced, and the toner transfers from the heating roller to the pressure roller. The cleaning member provided upstream of the conductive needle-like static eliminator can be greatly reduced in dirt and contamination.Since both members work together, the cleaning member can be made of felt.
It only needs to be replaced about 7 times for every 0 copies made, and the conductive acicular static eliminator does not need to be replaced even after 100,000 copies have been made. As a result, we were able to develop a static eliminator that has good quality image copies for a long period of time.

As shown in Figure 82, by integrally molding the cleaning member and the conductive needle-like member, it is possible to make them come into contact with the roller surface near the nip on the paper ejection side, where the offset prevention effect is highest. Ta.

The present invention can also be used for heating rollers. Furthermore, it is also effective to use in a pressure fixing device using an insulating elastic roller.

[Brief explanation of drawings]

Figure 1 is a side view of the fixing machine of the electrophotographic copying machine, Figure 2 (a
), FIG. 2(b), and FIG. 2(C) are side views of other embodiments of the present invention, FIG. 3 is a side view showing the measurement status of the amount of static electricity removed, and FIG. Diagram showing changes in the amount of static electricity removed, Part S
Figure (a) is a side view showing the installation position of the static eliminator, Figure S (
b) is a diagram showing the relationship between the static elimination position and the static elimination amount. lφ・Heating roller K・・Pressure roller 6・・Cleaning device 6a・・Cleaning web t・・Conductive needle-like member Ta・・Cleaning member (Grip・・Near the nip in the downstream direction. Patent application Person Canon Co., Ltd. Agent Arai - Department Figure 1 Figure 3 Figure 4 Drawing 1 Kukohiwa 1 Father (O history)

Claims (1)

[Claims] In a fixing device that fixes an image by conveying an unfixed image carrier between a number of rotating rollers, an insulating coating layer is provided on at least one surface of the rotating rollers in the longitudinal direction. A fixing device characterized in that a cleaning member and a conductive needle-like member are sequentially brought into contact with each other from the vicinity of a carrier discharge portion.