JPS63172187A - Fixing device - Google Patents

Abstract

PURPOSE:To improve durability and to reduce power consumption by selecting the temperature control mode of a lower set temperature to control a heating means if the temperature of a fixing means reaches a prescribed value in a short time and selecting the temperature control mode of a higher set temperature to control the heating means if said temperature reaches the prescribed time in a long time. CONSTITUTION:When a main switch of a device is turned on, a CPU 20 is operated and a heater 6 is operated through a comparator 19 and a relay 21. When the temperature of a heat roller 2 rises, the surface temperature of the heat roller 2 is monitored by a temperature detecting element 11. A temperature control mode I is selected in case of t<t0, and a temperature control mode II is selected in case of t>=t0. When the temperature control mode I is selected, a temperature T1 is detected by the comparator 16 and the heater 6 is controlled to keep the heat roller 2 at the temperature T1. When the temperature control mode II is selected, a temperature T2 is detected by the comparator 17 and the heater 6 is controlled to keep the heat roller 2 at the temperature T2, and the temperature control is switched after a certain time so that the heater 6 is controlled to keep the heat roller 2 at the temperature T1. Thus, the life of a pressure roller is extended and the power consumption is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fixing device using a heat fixing method that is installed in a copying machine, a laser beam printer, or the like.

(Prior Art) As a heat fixing method, a heat roller method, a one-chamber method, and the like are known, and both of them melt toner and fix it onto a recording material by heating. With a fusing device that uses this type of system, if the power is turned on when the ambient temperature is low, the temperature of the device will be as low as the surrounding temperature, so the temperature will rise to the temperature required for fusing. It takes time.

In particular, in a heat roller type fixing device in which a pressure roller is pressed against a heating roller, heat is absorbed by the heating roller, pressure roller, and recording paper during the initial rotation of the roller, which lowers the fixing temperature and causes the fixing There is a problem that the performance deteriorates, and in order to prevent this, conventional methods have been taken to set the standby temperature higher.

However, in this case, at the same time as the temperature rises inside the machine, the sponge-like rubber layer (which is sensitive to heat) that makes up the pressure roller is exposed to high temperature conditions for a long time, causing deterioration of the rubber layer such as loss of heat and hardness. The result was that the process was accelerated.

In order to solve such problems, a thermistor for detecting room temperature is installed inside the machine, and when the room temperature T is a predetermined temperature To, ■ When T≧TO, the temperature control temperature during standby is set to T1.
(■ When T < To, the temperature control during standby is first set to T2, and after a certain period of time is set to Tl (However, T2 > Tl
) A fixing device equipped with temperature control means has been proposed.

(Problems to be Solved by the Invention) However, with the above device, the room temperature detection device is costly, and since the thermistor is installed inside the machine, the room temperature cannot be accurately detected, and the temperature cannot be properly controlled. In addition to the problem, it is not possible to sufficiently compensate for the temperature drop of the fuser roller due to fluctuations in the input voltage to the device, so the temperature setting is set high in advance, and even if the input voltage decreases, the surface temperature of the fuser roller remains unchanged. Since the temperature is set so that the temperature does not drop below the fixing temperature of the toner, the set temperature may become higher than necessary, making it difficult to extend the service life of the pressure roller. If a method is adopted in which the rated power of the fixing heater is increased to compensate for the decrease in the power consumption, there is a problem in that an undesirable situation occurs from the viewpoint of saving power consumption.

Therefore, the present invention has been made to solve the problems of the prior art described above, and its purpose is to omit the device for detecting room temperature and reduce costs.
By controlling the temperature appropriately, it always maintains the best fixing performance, and even when using sponge-like rubber, etc., which has poor heat resistance, as a pressure roller, durability can be improved, and power consumption can be further reduced. An object of the present invention is to provide a fixing device that can perform the following steps.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a heating means, a fixing means for fixing a toner image on a recording material by being heated by the heating means, and a fixing means for fixing a toner image on a recording material by heating the heating means. In the fixing device, the temperature control means controls the heating means based on a detection signal from the temperature detection means for detecting temperature, wherein the temperature of the fixing means is set to a predetermined value based on the detection signal from the temperature detection means. It is equipped with a time detection means for detecting the time taken for the temperature of the fixing means to reach a predetermined temperature, and the temperature control means is configured to increase the set temperature as the time it takes for the temperature of the fixing means to reach a predetermined temperature increases. It has a temperature control mode, and is configured to select the temperature control mode based on the detection signal from the time detection means to control the heating means.

(Function) In the present invention having the above configuration, based on the detection signal of the one-hour detection means, if the time until the temperature of the fixing means reaches a predetermined temperature is short, a temperature control mode with a lower set temperature is selected; If the time is long, a temperature control mode with a high set temperature is selected and the temperature control means controls the heating means.

(Example) The present invention will be explained below based on the illustrated example. 1st
In the figure, reference numeral 1 indicates a heat fixing device, and this heat fixing device 1 includes a heat roller 2 and a pressure roller 3 that is in pressure contact with the heat roller 2. The heating roller 2 is A
A heat-resistant release layer 5 made of fluororesin is coated on a hollow cylindrical body 4 made of a material with good thermal conductivity such as stainless steel, stainless steel, or iron.

Inside the heating roller 2, a heater 6 such as a halogen lamp is provided along the longitudinal direction in the center thereof, and the heat generation of the heater 6 is controlled by a temperature detection element ↓1 and a temperature control means 12, which will be described later. The surface of the heating roller 2 is heated to a predetermined temperature. On the other hand, the pressure roller 3 is
A core bar 7 made of iron or the like is coated with a heat-resistant elastic layer 8, such as a silicone rubber layer on a relatively thick silicone sponge, to ensure a sufficient nip.

Further, the heating roller 2 is coated with a release agent coating member 9 such as a heat-resistant porous fluororesin (for example, Fluoropore; trade name).
A mold release agent such as silicone oil is applied, and the mold release agent is uniformly applied onto the heating roller 2 by the metering blade 10. Furthermore, the metering blade 10 also cleans toner offset onto the heating roller 2. The surface temperature on the heating roller 2 is detected by a temperature detection element 11 consisting of a thermistor, and the temperature control means 1
2 is controlled. In the figure, reference numeral 13 indicates an entry guide for guiding the entry of the transfer material, and reference numerals 14 and 15 indicate separation claws in contact with the heating roller 2 and the pressure roller 3, respectively.

Reference numeral 23 indicates a recording paper, and 24 indicates a toner image.

FIG. 2 is a block diagram showing an embodiment of the temperature control means 12, which is a characteristic part of the present invention. Since the resistance value of the thermistor constituting the temperature detection element 11 changes depending on the surface temperature of the heating roller 2, this change in resistance value is converted into a voltage and the temperature is detected by the comparators 16, 17, and 18. In addition, the comparator 19 turns on and off a relay 21 to adjust the temperature of the heating roller 2, etc.
controlled by

FIG. 3 shows temperature control mode d and temperature control mode 2, which are control contents of the CPU 20. In temperature control mode E, the standby temperature is set to a low temperature, and in temperature control mode ■, the standby temperature is set to a high temperature. here,
The comparator 16 corresponds to the temperature TI shown in FIG.
Further, the comparator 17 corresponds to the temperature T2 shown in the same figure,
Further, the comparator 18 has reference voltages 16a, 17a, and 18a respectively set to correspond to the temperature T3 shown in the figure, and the comparator 18 corresponding to the temperature T3
and a portion that monitors the time until the comparator 18 of the CPU 20 is inverted (the time until the temperature T3 is detected).

Next, the operation of the above embodiment will be explained.

When the main switch (not shown) of the device is turned on, C
The PU 20 operates to operate the heater 6 via the comparator 19 and relay 21. When the temperature of the heating roller 2 is increased by the heater 6, the surface temperature of the heating roller 2 is monitored by the temperature detection element 11. Here, main switch O
After N.

The CPU 20 determines the time t until the predetermined temperature T3 is reached;
In other words, the time t until the comparator 18 is reversed is monitored, ■ When t < t o, temperature control mode I is selected, and ■
When t≧to, select temperature control mode ■. Note that to is a constant value determined based on the rating of the heat fixing device 1 and the like.

When the temperature control mode is selected, after the comparator 16 detects that the temperature has reached T1 (comparator 1
6), the temperature T
The heater 6 is controlled to adjust the temperature with I.

In addition, when temperature control mode ■ is selected, comparator 1
After detecting that the temperature has reached T2 by 7 (after the CPU 20 detects that the comparator 17 has been inverted),
The heater 6 is controlled to adjust the temperature at the temperature T2, and after a certain period of time, the heater 6 is switched to be controlled at the temperature T1. The reason why the temperature control is switched to the lower temperature T1 after a certain period of time has elapsed is because the pressure roller 3 is also sufficiently warmed, so that the temperature drop during rotation of the roller is small.

If the room temperature is low and the temperature rise time is long, or the input voltage is low and the temperature rise time is also long, the fixing roller (
Heating roller 2, pressure roller 3) Since the temperature drop at the initial stage of rotation is large, it is necessary to raise the standby temperature in advance, but in this example, after turning on the power, the predetermined temperature T
The temperature control mode is selected by monitoring the time until the temperature reaches 3, and even in the above case, temperature control mode ■ is selected and the standby temperature is set high, so there is no chance of fusing failure. do not have.

On the other hand, if the input voltage is high even if the room temperature is low, the temperature drop at the beginning of the fixing roller rotation is small because the amount of heat supplied is small, but in this case the rise time is also short, so the temperature control temperature with a low standby temperature is selected, and a situation where the set temperature becomes too high does not occur.

In other words, the set temperature during standby is set high only when the temperature of the fixing roller tends to drop at the initial stage of rotation of the fixing roller.
In other cases, the set temperature during standby can be lowered, so the life of the pressure roller 3 can be extended and unnecessary power consumption can be suppressed.

Note that when changing the set temperature using the conventional room temperature detection method, the standby temperature increases only when the room temperature is low. Sometimes, the temperature drop is large and the fixing performance is poor.Also, if the room temperature is low but the input voltage is high enough, the standby temperature may be high and the pressure roller may be heated more than necessary, shortening its life even though the temperature drop is small. Problems such as shortening the length may occur.

Next, the above embodiment will be explained by giving a specific example.

A heater 6 of 100 V and 500 W was used to heat the heating roller 2 from inside. The heating roller 2 used had an outer diameter of 26.2φ and an An core metal wall thickness of 1.5 t. In addition, the temperature T3 is 140°C, and the time to is 3
If it is less than 30 seconds, it is set to temperature control mode (170°C during standby, 180°C when fixing), and if it is longer than 30 seconds, it is set to temperature control mode ■ (190'C during standby for 1 hour after turning on the power! (The temperature was set to 190° C. during fixing, and after one hour, the temperature was set to 170° C. during standby and the fixing vf was set to 180° C.).

Under these conditions, A4 size paper is 3.5mm thick at a speed of 15 sheets per minute with a paper feed speed of 90 IIm/sec.
When paper was continuously passed through a heat fixing stirrup in which a nip portion was formed, the surface temperature of the heating roller 2 changed as shown in FIG. That is, when the surface temperature of the heating roller 2 is 25°C, which is the same as the room temperature, it takes 25.5 seconds to reach 140°C after the power is turned on with a 100V input.
Since the time is less than 30 seconds, temperature control mode is selected,
During standby, the temperature is controlled at 170°C, and the temperature rises to 180°C just before the paper is fed, and as the paper passes, heat is absorbed by the paper and the pressure roller 3, and the temperature drops to 175°C. After that, the temperature is controlled at 180°C. Ta. Furthermore, when the surface temperature of the heating roller 2 is 10°C, which is the same as room temperature, it takes 35.5 seconds to reach 140°C with 100cm of manual power after the power is turned on.
Since the time is 30 seconds or more, temperature control mode ■ is selected,
During standby, the temperature is controlled at 190℃, and the temperature increases by 1
The temperature was lowered to 80°C, and then the temperature was controlled at 180°C. Note that after one hour, the temperature was controlled at 180° C., and at that time, the change in surface temperature of the heating roller 2 during paper passing was the same as in the temperature control mode.

In the above specific example, we explained the case where the input voltage was kept constant (IOOV) and the room temperature was changed.
Next, a case where the input voltage is changed will be explained.

Even if the surface temperature of the heating roller 2 is 25°C, which is the same as room temperature, when the input voltage is 85V, it takes 33.5 seconds to reach 140°C after the power is turned on, so temperature control mode ■
was selected. In this case, the temperature was controlled at 190° C. during standby, and the temperature drop during paper feeding could be kept to about 183° C. On the other hand, even if the surface temperature of the heating roller 2 is 10°C, which is the same as room temperature, when the input voltage is 110V, it takes 28.5 seconds to reach 140°C after the power is turned on.
Temperature control mode I was selected. In this case, since the temperature rises quickly, the temperature is regulated at 170°C during standby, and then 180°C just before the paper is fed, and the temperature drop during paper feeding can be kept to about 173°C. .

For comparison, when the set temperature was changed using the conventional room temperature detection method, the results were as follows.

For example, when 20°C is the temperature for switching the set temperature, if the room temperature is 25°C and the input voltage is 85V, the temperature will exceed 20°C, so the temperature control mode will be selected, and even though the temperature rise is slow. 170℃ during standby
The temperature was controlled at a low temperature, and even if the temperature was raised just before the paper was fed, it only reached about 176°C, and after the paper was fed, it dropped to 168°C, resulting in poor fixing performance. Also, the room temperature is 10℃
When the input voltage is 110V, even though temperature control mode E is sufficient as described above, since the temperature is below 20°C, temperature control mode ■ is selected, and the pressure roller 3 is heated more than necessary. Ta.

In addition to the above-mentioned embodiment, the above embodiment is effective in controlling the temperature when the members near the heating fixing device l are cold (immediately after the main switch is turned on). In other words, while the entire apparatus has cooled down and has not yet warmed up sufficiently, the temperature control mode ■ is selected and the surface temperature of the heating roller 2 is controlled in advance at a temperature sufficiently higher than the toner fixing temperature during standby. , it is possible to compensate for the temperature drop at the initial stage of startup, and once the entire device has sufficiently warmed up, the temperature control mode is selected and control is performed by lowering the set temperature during standby, so that the inside of the machine can be controlled by lowering the set temperature during standby. It is preferable that the temperature does not rise above that level.

In the room temperature detection method, the temperature of the fixing device itself is not detected.
Since it detects the temperature inside the machine, if the fixing device itself is higher than the temperature inside the machine, such as when turning off the power and then turning it on again, the standby temperature may be set to a high value by mistake. There are problems such as curling of the recording paper and easy occurrence of wrinkles on the recording paper due to the high fixing temperature.This embodiment can also solve these problems.

In the above embodiment, two types of temperature control modes are set to control the temperature, but two or more types of temperature control modes may be set. For example, if there are three types of temperature control modes, the time t until the predetermined temperature T is reached is different from the preset time to, t. ■ 1<1. When temperature control mode ■ t≦1<1. When t≧t1, temperature control mode m is selected. Here, in the temperature control mode, the temperature during standby is T4', and the temperature during fixing is T4'.
4, and in temperature control mode ■, the temperature during standby is Ts.
', the temperature during fixing is Ts, and in temperature control mode (2), the temperature during standby is T6', and the temperature during fixing is Ts. Also, Ts'>Ts'>T4', Ts'≧
The temperature is set so that the relationships Tb, Ts'≦T5, and T4'≦T4 are satisfied.

That is, when the temperature is low or the input voltage is low, mode ■ is selected, and the temperature is controlled at higher temperatures such as T6' during standby and T6 during fixing to prevent fusing failures, and in normal conditions, mode ■ is selected. The temperature is controlled at a slightly higher temperature T5' during standby, so that the temperature can be raised to a sufficient fixing temperature T5 just before fixing, and when the temperature is high or the input voltage is high, mode E is selected and the temperature is set to T4' during standby. During fixing, adjust the temperature at a low temperature of T4 to avoid overheating.

By doing so, it is possible to extend the life of the pressure roller 3 while always maintaining the best fixing performance.

Next, the other embodiments mentioned above will be explained by giving specific examples.

A heat fixing device 1 having the same configuration as in the above embodiment was used, and the rise time for switching the temperature control mode was set to 140° C., to was set to 20 seconds, and tl was set to 30 seconds. In addition, when temperature control mode I is on standby, Ta' = 165
℃, during fixing Ta = 180°C, temperature control mode ■ is standby Ts' = 170°C, fixing T5 = 180°C, temperature control mode m is standby T6' = 190°C, fixing T6 = 190°C And so. Mode T was designed to switch to mode H one hour after the main switch was turned on.

By doing so, it has become possible to select the optimum temperature control mode for changes in room temperature and input voltage. In particular, when the temperature of the heating roller 2 rises quickly, the standby temperature can be set as low as 165°C, making it possible to significantly extend the life of the pressure roller 3. According to experiments conducted in the present invention, the pressure roller 3 The lifespan of the set temperature is 10
As the temperature rises, it becomes about 80% shorter.Compared to the conventional case where the temperature was controlled at the fixing rotation temperature of 180°C during both standby and fixing, when the temperature was controlled in mode mode (165°C during standby). It was found that the life of the pressure roller 3 was extended by 1.4 times.

Please note that the temperature during standby is set low in advance, and the
) In order to raise the fixing temperature to the fixing temperature within 10 seconds before the paper is fed, for example, in order to raise the temperature from 165°C to 185°C, the heating fixing device 1 must have a rating of 9.
It turned out that a 50W heater 6 was required.

(Effects of the Invention) The present invention has the above-described configuration and operation, and since the temperature control mode is selected in accordance with the rise time of the temperature of the fixing means, a device for detecting the room temperature is omitted. It is possible to reduce costs, maintain the best fixing performance by controlling the temperature appropriately, eliminate curls and wrinkles on the recording paper, and extend the life of the pressure roller. This makes it possible to further save power consumption.

Note that the CPU used to control the device can be used as the time detection means, so the cost increase due to the addition of the time detection means is hardly a problem, and the device for detecting the room temperature can be omitted. If this is included and the entire device is viewed, the cost can be reduced as described above.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic diagram of the entire device, FIG. 2 is a block diagram showing temperature control means,
FIG. 3 is an explanatory diagram of the temperature control mode, and FIG. 4 is a graph showing changes in the surface temperature of the heating roller when the apparatus shown in FIG. 1 is actually operated. Explanation of symbols l... Heat fixing device 2.3... Fixing means (heating roller 2, pressure roller 6,
... Heating means (heater) 11 ... Temperature detection means (temperature detection element) 12 ... Temperature control means (comparator 16° 17.19, I)
21, CPU 20) 22... Time detection means (comparator 18, CPU 20) 23... Recording material (recording paper) '-51 Figure 2

Claims (1)

[Scope of Claims] A heating means, a fixing means that is heated by the heating means to fix the toner image on a recording material, and a heating means that operates based on a detection signal from a temperature detection means that detects the temperature of the fixing means. A fixing device comprising: a temperature control means for controlling the temperature; The temperature control means has a plurality of temperature control modes in which the set temperature is increased as the time required for the temperature of the fixing means to reach a predetermined temperature increases, and the temperature control means is configured to have a plurality of temperature control modes in which the set temperature is increased as the time required for the temperature of the fixing means to reach a predetermined temperature is increased based on a detection signal from the time detection means. A fixing device characterized in that the fixing device is configured to control the heating means by selecting a temperature control mode.