JPS5961863A - Heat fixation device - Google Patents

Abstract

PURPOSE:To improve the heat absorption efficiency in heat fixation and to improve the reliability and the durability of a device by making the roughness of the internal surface of a rotating body higher in the internal-surface end area than in the center area so that the end area has higher heat absorptivity than the center area. CONSTITUTION:The internal surface roughness of a cylinder with a uniform diameter which is manufactured by a drawing method is <=1mum, the heat reflectivity is large, and the heat absorptivity is small. Then, the entire internal surface is roughened into an about 3mum nearly-uniform rough surface and then the end part is roughened as shown by R to about 8mum. The external surface temperature distribution of the fixation roll which is roughened to 3mum roughness both in the center area S1 and end area S2 shows a greater temperature drop in the end part area, but the fixation roll R has nearly uniform temperature distribution. Consequently, the heat of the end area is absorbed by the fixation roll efficiently, the temperature rise of air outside of the roll of a member is suuppressed extremely, and the heat absorptivity is increased to improve the reliability and durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat fixing device that heats and fixes an image supporting material that supports an unfixed image (for example, a powder image) or an object to be heated such as an unfixed portion, and relates to the device. .

Conventionally, in this type of apparatus, a heated fixing roller in which a heating source is provided inside the fixing roller has been frequently used in order to effectively utilize heat and stabilize the heat distribution on the surface of the fixing roller.

As for this heating fixing roller, the present inventor had previously applied for the
In No. 181274, a thin-walled fixing roller was proposed. This has a smaller heat capacity and higher thermal responsiveness than conventional ones, so it has the effect of shortening the wait time until a predetermined temperature is reached.

On the other hand, the heat fixing roller is composed of eight metal rollers with good thermal conductivity. Metal rollers are mass-produced, and are formed by drawing, forging, etc. in order to be inexpensive and to reduce product variation. The inner surface of the metal roller formed in this manner has particularly good surface smoothness. This smoothness is convenient for defining the thickness of the metal roller and is suitable for mass production.

Conventional heat fixing rollers have relatively thick metal rollers in consideration of strength and heat retention. This thick wall thickness means a large heat capacity, and it is possible to gradually absorb heat from an internal heating source, and it is always advantageous to avoid large temperature changes on the surface of the fixing roller against heat loss during fixing. However, on the other hand, weighted tights have the major drawbacks of being long-lasting and slow to respond to temperature adjustments.

The smoothness of the inner surface of the roller has the advantage of making the heat distribution uniform in the longitudinal direction of the fixing roller. On the other hand, the temperature rise due to heat release in the end region was a fact that could not be overlooked.

However, in order to solve the drawbacks of the conventional thick heat fixing roller, if the aforementioned thin metal roller is used, the temperature on the roller surface will rise faster, but on the other hand, the temperature inside and outside the roller will increase faster. A problem arose in that the temperature rose abnormally compared to the case described above. This problem r, -f, the heating means inside the roller overheats and deteriorates its durability, 17th and 41st, the temperature inside the fixing device rapidly increases, and the safety mechanism (e.g. fuse) inside the device is activated. Make it incapacitated and Lt. Furthermore, the heat fixing roller is made into a cylindrical type with both ends open. The table, especially this problem, is a big obstacle and sweat 17
Oh yeah. In addition, when the heating means normally has power supply contacts to the heating element at both ends, it has been seen that the contacts often break due to abnormal temperature rise due to heat release from the ends. . This problem becomes even more serious when the heater light distribution is made stronger at the end regions than at the center in order to prevent heat loss and temperature drop at the end surfaces of the rotating body.

As a result of investigating this problem, the inventor of the present invention found that the cause of this problem was the thin inner surface of the roller, especially the surface smoothness of the roller end region. In other words, the smoothness of the inner surface, which was a slight advantage in the case of a thick roller, becomes a disadvantage in the case of a thin roller.

The present invention aims to solve the problem caused by the heat from the heating source being wastefully released from the end of the rotating body as described above, and by making the rotating body effectively absorb the heat from the heating source,
The present invention provides a heating device that can suppress temperature rise in the end region of a rotating body.

To that end, the present invention is characterized in that the surface roughness of the rotating body surface in the end regions of the rotating body is further improved so that it has a higher heat absorption rate than the heat absorption rate in the central region of the rotating body. This term "roughness" refers to the roughness of a surface with the same degree of roughness.
It includes at least one of the number of concavities and convexities per unit length or the difference between the valleys and peaks of the concavities and convexities.

The present invention will be explained below with reference to the drawings.

1 to 3 are explanatory diagrams of an example of a heat-fixing rotating body applied to the present invention, and FIG. 4 is an explanatory diagram of an embodiment of the present invention.

R in FIG. 1 is a fixing roller formed by the following rows.

A cylinder with a uniform inner diameter is produced by smoothing the inner surface of a size aluminum (JISA5056) material by a rolling drawing method and leaving a machining allowance on the outer diameter. Thereafter, the outer diameter is cut to obtain a cylindrical roller having a wall thickness d of 16t, a length t, and an outer diameter r. The diameter of the cylinder's 1-ra inner surface is less than 1μ, and it is almost mirror-like.

Next, the inner surface of the cylindrical roller is roughened to a surface roughness of approximately several microns to 1() micron. In this example, the material is passed through a circular metal brush that matches the uniform inner diameter of the cylindrical roller, and the entire inner surface is roughened to a substantially uniform roughness of about 3 microns. This rear end region inner surface S2 was further roughened to about 8 μm.

Suitable surface roughening treatments include sandpaper, blowing, blasting, etc. (by-handed treatment, lathe processing, chemical conversion treatment with acid or alkali, etc.).

FIGS. 2(4), 2(B), and 2(C) are enlarged views 17 of the roughness of the fixing roller R. FIG. 2 (4) shows the inner surface roughness of a cylinder with a uniform inner diameter manufactured by the pultrusion method. Although it has many irregularities, the size is about 1 μm or less, and the heat reflectivity is extremely high and the heat absorption rate is low. FIG. 2 (Y3) shows the roughness of the inner surface S1 of the central region in FIG. This roughness has a large number of 3 μm unevenness, and although the number of unevenness is smaller than in Figure 2 (5), the difference in size between the valleys and peaks of the unevenness becomes larger and the surface area increases [7 ing. In other words, the surface roughness in FIG. 2(g)) is greater than that in FIG. 2(4). FIG. 2 (0 indicates the roughness of the inner surface S of the end region in FIG. 1).

The surface roughness is 8 μm of unevenness, which is less than that shown in FIG. 2 (5) and more than that shown in FIG. 2 (B). However, the difference in size between the troughs and peaks of the unevenness is sharper than in FIGS. 2(5) and 2(B), and at the same time, the surface area is increased to 7. In other words, Figure 2 (C
) has a higher roughness than Figure 2 (B).

Next, the effects of the main fixing roller R will be explained with reference to FIG. In the figure, a curved line indicates the outer surface temperature distribution of the fixing roller R, and a curved line Bt indicates the outer surface temperature distribution of the fixing roller with a roughness of 31 tm in both the center region and the end region. The heater used had a flat distribution with equal light distribution at the ends and the center.

Curve B has a large temperature drop in the end region, which is 10 to 15 degrees Celsius lower than in the center region.Then, there is an uneven temperature distribution over the entire length of the roller. The heat is not absorbed by the fixing roller, but is caused by the air outside the roller or by the rotating member.

On the other hand, in the song ff@A, the temperature drop is only about 5° C. in the end region, and a uniform temperature distribution is obtained at the mouth as a whole. The heat in the tapered end region is efficiently absorbed by the fixing roller and the end of R, and the temperature rise of the air or members outside the roller is suppressed as much as possible.

Increasing the degree of roughness by deepening the interval between the peaks and valleys of the unevenness or increasing the number of peaks toward the end has the following effects.

In the case of a heater manufactured by enclosing a filament in a glass tube as an internal heating source, such as a halogen heater, the electrode part is a part of the filament pulled out from the glass and held in an insulating ceramic as an electrode. There are many cases.

is generally inferior. For this reason, efforts have been made to make the heater longer than the object to be heated so that the temperature at the connection part is as low as possible. In the case of heating, there was a problem in that the length of the heating device had to be increased in order to make it longer than the object to be heated.

However, by increasing the unevenness at the ends, it became possible to make the ends more compact. Furthermore, it becomes possible to further downsize equipment and reduce the cost of heat resistance.

Similarly, even if the roller normally radiates a large amount of heat to the atmosphere from one end, according to this example, the heat absorption efficiency can be further improved at the end. Therefore, since the amount of heat escaping to other places can be reduced, the need for consideration such as creating a heater that supplies more heat than the escaping heat meter, as in the past, has been reduced.

In addition, by increasing the amount of heat supplied from the heater at the end, in the case of a heater that has electrodes at the end, the heat resistance of the heater near the electrode part described in a above was significantly deteriorated. It has become possible to deal with this problem by changing the heat absorption efficiency of the heated object without particularly increasing the heat resistance.
The effect is great.

For example, if the effects of this embodiment are shown in the drawings, as shown in the direction F in FIG. 3, the filament portion 32 of the heater 41 and the filament portion 3
2 and the power supply section 31 can be provided.

This allows the device to be downsized in the longitudinal direction of the roller.

Since the present fixing roller has a thin cylindrical roller in the above-described configuration, it also has the following effects.

A 1.2 KW halogen heater was used as a heat source at the center of the interior of the fixing roller R, and the temperature was adjusted by keeping the surface of the fixing roller at a set temperature of 18°C (1°C). The standard value for thin wall (1.6t
A cylindrical roller (hereinafter referred to as the reference roller) is used, whose inner surface is not subjected to a curved surface treatment and whose inner surface has a hollow mirror surface and is heated and controlled under the same conditions.

The time it takes to reach the set temperature of 180°C is about 20 seconds with the late semi-roller, which is much faster than conventional fixing rollers, but with the present fixing roller R, the time can be further shortened by about 2 seconds to about 18 seconds. In other words, in the present fixing roller R, the heat absorption efficiency can be improved and the waiting time can be shortened.

Regarding the temperature change on the roller surface during temperature adjustment, the present fixing roller R showed a more stable change. Also, during the fixing process, the temperature at a point 5 degrees away from the end area of each roller is 200 degrees Celsius for the standard roller, while the temperature for this fixing roller R is 40 degrees lower, stable at 1fi (+ 'C). As is clear from this, the heat from the heat source is absorbed more efficiently into the metal layer of the main fixing roller R, especially in the edge region, than by the wide roller.In other words, there is no abnormality around the heating fixing roller or inside the device. Temperature rise can be suppressed, and deterioration due to abnormal temperature rise of the heating source itself can be prevented.

Therefore, it is possible to use a material with low heat resistance as the heat resistant member of the 1111 heat source in one step, and as a whole, it is possible to create a constant magnification device that is inexpensive and has a long life. Furthermore, as a safety mechanism, it is possible to use a temperature fuse or thermoswitch that is rated to react in a low temperature range, which improves the safety of the meter.

As is clear from the results described above, (a) the fixing roller R can achieve high thermal responsiveness from the heat source and can simplify temperature control. A control method using a linear function of time and temperature rise can be applied.

Next, a second example in which this fixing roller R is incorporated into a fixing device is shown.
This will be explained with a diagram.

In Fig. 2, 1d1 (rough surface heater explained in Fig. 1)
A metal roller 5 having a wall thickness d and having a releasability # and a covering layer 6 are provided on the surface of the metal roller 5. 2 is a pressure roller that comes into pressure contact with the heat fixing roller 1, and a one-component R
Apply TV silicone rubber primer 72.
A sponge layer 8 made of silicone sponge (having a large number of independent pores) is adhered to the second layer, and an elastic PJQσ layer 9 is further coated with IlT V silicone rubber. This pressurization "1-R2 surface t, generally R
After applying TV (room temperature vulcanization type) silicone rubber, it is polished to a l-2 finish to adjust its shape as a roller.

Furthermore, the releasable coating layer 6 of the heat-fixing roller 1 is coated with cleaning means such as the d1 cleaning blade 16 and
Anti-offset liquid application means 3 (as shown in the figure, silicone oil impregnated member 10
(having a damage prevention member 12 and a continuous porous member 11) are in contact with each other. Together with the separating claw 23, a transport path for the paper P is secured. Reference numerals 161 and 162 are paper ejection rollers Q that pinch and convey the fixed paper P to the outside of the image forming apparatus or to the stacking section.
26 is a similar lower support piece. Reference numeral 27 denotes a guide member within the image forming apparatus that removably supports the supporting workpiece 26 of the fixing unit. Reference numeral 28 denotes a fixed workpiece in each position of the JI solar panel, and a thermistor 13. It is spaced apart from the supporting work surrounding it with a gap.

Now, toner f formed by a predetermined image forming means
A sheet of paper P having an image T is transported along with the movement of a belt 15 hooked around a pair of transport rollers 14. Next, the paper P is transferred to the belt 15 or the guide member 13a, and the heating and pressure roller 1
, 2 is guided to the pressure contact portion formed by the two. At this pressure contact part, the toner image T
is fused and fixed on the paper P, and is discharged together with the paper P.

In this embodiment, the diameter r of the metal roller 5 is 25 mm, and the wall thickness d is 2.5 tm.

This elastic coating layer 9 is thinner than the sponge layer 8, and the temperature distribution when heated is easily stabilized.

Another configuration in this embodiment includes the pressure adjusting means described above.

In this example, a pressure of about 15 to 9 is always applied between the heat fixing roller 1 and the pressure roller 2.

The operation of this cam means 18 is such that the pressure is released when there is an abnormality (jam) in which the recording material such as paper P is stopped between the rollers.
It is done with the aim of zero or a number, /=).

Further, a contact type thermistor 13 is provided on the circumferential surface of the heat fixing roller 1. is elastically pressed by a leaf spring 24 to maintain a predetermined pressure contact force.

This thermistor 13. has a resin tape-like material on its surface so as not to damage the surface of the fixing roller 1, and holds a temperature sensing element (not shown) with a sponge-like elastic material. Reference numeral 29 is a fuse serving as a safety mechanism that detects an abnormal temperature within the apparatus and cuts off the power to the heating means 4.

Reference numeral 23 separates the paper P from the heat fixing roller 1 with a separating claw.

Reference numeral 22 designates a guide plate on the side of the pressure roller 2. On the other hand, the heat-fixing roller 1 has its inner surface roughened by roughening, as described above, so that it efficiently absorbs heat from the heating source. Especially in the edge region, efficiency is greatly increased. This rate of heat absorption of 1 νl is much faster than that of a structure with a lip or a mirror surface. That is, the time it takes for the surface of the heat-fixing roller 1 to reach the set temperature is shortened, and at the same time, the heat from the heating means 4 escapes through the opening of the roller 1 (which is larger than the conventional roller because it is a roller with a uniform diameter). This can prevent abnormal temperature rise inside the device.

While the surface of the heat fixing roller 1 is being heated, the pressure roller having the above-mentioned configuration is used as a 0-mass pressure roller that promotes heating of the heating roller surface and shortens the wait time at startup as a whole as described below. The effect of the second sponge layer will be explained. Since the sponge layer 8 has a large volume occupied by gas such as air in addition to the sponge component, the thermal conductivity of the sponge layer 8 is much lower than that of the coating layer 9. In other words, the amount of heating required by the heating fixing roller 1 to maintain the entire pressure port 22 itself at a predetermined temperature is only a small amount compared to the conventional one, and a large amount of heat is wasted and wasted on other things. It is a highly efficient product that has greatly improved its thermal efficiency.

Due to the above structure, the coating layer 9 has higher thermal conductivity than the sponge layer 8, so the wait time at startup (the time required until the process can start) is extremely shortened. . Furthermore, even if the apparent hardness of the roller surface is the same, the above embodiment having the sponge layer 8 is more easily deformed than a single solid.
The pressure contact area between the rollers can be widened.

Generally, the heat of the heat fixing roller is conducted to the pressure roller side at the pressure contact portion with the heat fixing roller, prolonging the time it takes for the heat fixing roller to reach a predetermined temperature. However, in this example, due to the configuration of the pressure roller 2 described above, heat is quickly transferred only to the thin layer 9, and conversely, it helps heat transfer in the generatrix direction of the fixing roller 1. As a result, the heating state of the heating fixing roller 1 becomes more uniform throughout the entire temperature than when printing the roller 1.
(in this example, 10
~Wait time of about 15 seconds).

Also, during the fixing action or while waiting for the next fixing, the amount of heat necessary to maintain the fixing state is only needed to heat the thin metal roller 5 and the thin coating layer 9; It requires less electricity than before to keep the surface at the set temperature. At the same time, on the inner surface of the heat fixing roller 1,
Since a thermal barrier layer is formed on the uneven portion to prevent temperature changes in the roller, the heating fixing roller 1
It is possible to prevent a sudden drop in temperature on the surface of the surface and to quickly respond to heat supply. In other words, it has become possible to obtain a roller configuration that shortens the weight-up time and causes almost no falling phenomenon during the fixing operation.

Therefore, even if the amount of heat generated by toner is the same per unit time,
Since contact heating can be performed stably for a long time, heat can be applied to the toner image (or paper P). At this time, the paper P, which is an example of a supporting material, has wrinkles that tend to be seen during fixing, but even though it has not been processed into an inverted crown shape, which is generally used as a treatment for wrinkles. It did not occur regardless.

Here, the thickness d of the heat fixing roller 1 will be explained.

As the wall thickness d becomes thinner, the time required for heating becomes shorter, and the wait time of the entire fixing device can be reduced.

When making such a roller as thin as possible, a strength meter (2) is generally used to maintain mechanical strength, taking into consideration the roller diameter, Young's modulus of the material, etc.

However, even if the wall thickness is set to obtain a predetermined strength or the inner surface is roughened, the temperature distribution on the surface of the heated fixing roller alone may become uneven, resulting in a slight decrease in fixing performance. That's the headline. Solve this 7,
The minimum necessary wall thickness to shorten the weight-up time is a wall thickness that allows for easy transfer of heat in the direction of the fuser roller generatrix, and a total pressure that is sufficient to prevent the core metal of that thickness from fluctuating. It is most effective to bring the pressure roller into contact with the pressure roller.

The inventor has determined that the wall thickness d satisfies the formula 5≦d≦r for the outer diameter r(-) of the rotating body.
10 is preferable, and considering the heat mobility in the IIMI+ direction as a single roller, 1! -Shadow d≦-R in knee
10 I found out that there is and is more preferable.

Furthermore, they also found that if the wall thickness d becomes thicker, such as when the outer diameter r is 30 or more, the heat capacity increases, so if it is 3 degrees or less in consideration of strength, a desirable thermal conductivity can be obtained. is.

When the heat-fixing roller is made of aluminum, the most preferable method is corrosion treatment with hydrochloric acid. The present invention is particularly effective for rotating bodies such as the open roller shown in FIG. 1, which has wide openings at both ends. .

This is because when an open roller with a low heat absorption rate is used, rather than the open roller itself being heated, the heat dissipated from the roller opening causes an abnormal temperature rise in the fuser cabinet, resulting in a large heat loss inside the device. This is because there is a problem in that the fuse melts quickly and the device stops, and the present invention has the effect of solving this problem. The present invention is not limited to the above embodiments, but includes all those having the same technical idea.

As explained above, the present invention has high heat absorption efficiency, reduces wait time, and can perform heat fixing at low cost and with high reliability and durability.

[Brief explanation of the drawing]

Figures 1, 2 (4), (B), (C) and 3
The figures are explanatory diagrams of a fixing rotating body applicable to the present invention, and FIG. 4 is an explanatory diagram of an embodiment of the present invention. 2 is a pressure roller, 4 is a heating means,
5 is gold FtIir + - la, 6 is a releasable coating layer, 8 is a sponge layer, 9 is an elastic coating layer, R constant fixing roller, Sl is the inner surface of the central region %, and S2 is the inner surface of the end region. Applicant Canon Co., Ltd. Ne1 Agent Marushima f4-

Claims (1)

[Claims] A heating fixing device comprising: a rotating body having an inner surface with roughness greater in end regions than in a central region; and heating means provided inside the rotating body.