JPH0934306A - Fixation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly obtain a first copy by shortening a rising time by making an output of a heat source (values of Watt) two times or more as much as an output required for maintaining the required fixation temperature. SOLUTION: Since energy of two times or more as much as heat capacity of a balanced condition is required for raising temperature by 100 deg.C for 10 seconds of a standby time being sensibly toler-able to obtain a first copy in a device fixating a copy of normal 10PPM, a halogen lamp 3 (heater) is heated by giving energy two times or more as much as the required fixation temperature. In this case, it is prevented to affect badly to a life time of the lamp by using two halogen lamps and driving them in parallel. After that, a long life time can be obtained by properly switching them at the time of heating and driving them. After it reaches the required fixation temperature, if the temperature is dropped, pulse heating of a longer cycle than a high frequency wave, for example, is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in a copying machine, a facsimile machine, a printer or the like, and more particularly to a fixing device for melting toner by heat energy and fixing it on the surface of a recording medium such as paper. Regarding

[0002]

2. Description of the Related Art Generally, in a copying machine, a halogen lamp having a fast rise is used as a heat source so that the first copy can be obtained quickly. In this case, as the halogen lamp, one having a sufficiently high output (wattage) is selected, and after the required fixing temperature is reached, a standard temperature separately determined is set as a reference, and when the temperature is higher than that, the heat source is turned off. When the temperature is low, the heat source is turned on.

Generally, the surface temperature of the heat roller in the electrophotographic process needs to be 170 to 180 ° C. However, in the standby state, in order to save power, the temperature is kept at room temperature or in a preheated state near 80 ° C., and the temperature rise in the apparatus is suppressed to a minimum value. Further, for driving the heat source, a method of using a pulse having a specified interval and controlling with a gate circuit is adopted (for example, Japanese Patent Laid-Open No. 63-77076).

FIG. 4 shows a conventional fixing device for melting toner by heat energy and fixing it on the surface of paper.
It is a block diagram which shows the example of 1 structure. In the figure, 1
Is a fixing roller, 2 is a facing roller, 3 is a halogen lamp,
4 is a thermistor, 5 is a commercial frequency power source, 6 is a control device, and SW is a switching circuit.

As shown in FIG. 4, in the conventional fixing device, the halogen lamp 3 is housed inside the fixing roller 1, and the control device 6 controls the on / off of the switching circuit SW to supply the power of the commercial frequency. The halogen lamp 3 is energized from 5. In this case, the halogen lamp 3
When the temperature is detected by the thermistor 4 and reaches a predetermined temperature or higher, the power supply 5 is turned off, and conversely, when the temperature is lower than the predetermined temperature, the power supply 5 is turned on and the required fixing temperature is maintained.

The fixing device having the structure shown in FIG.
When the device is large, its heat capacity is also large, so there is little problem of overshooting, hunting, etc. occurring at startup. However, as miniaturization of the fixing device progresses for downsizing and energy saving, the occurrence of overshoot and hunting becomes a problem.

FIG. 5 is a diagram showing an example of the relationship between the drive time and the change in the fixing temperature of a conventional fixing device. The horizontal axis of the figure is time t, and the vertical axis is temperature T.
o indicates the minimum temperature in the off state, and Tf indicates the required fixing temperature.

The conventional fixing device shown in FIG. 4 is similar to that shown in FIG.
As shown in, the minimum temperature To is maintained in the standby state. When the power supply 5 is turned on during use and the temperature of the fixing roller 1 becomes higher than the required fixing temperature Tf,
When the power supply 5 is turned off and the temperature drops below a certain temperature, the power supply 5 is turned on again and the temperature is maintained near the required fixing temperature Tf. However, as is clear from FIG. 5,
Since the temperature fluctuates in a relatively large range around the required fixing temperature Tf, the temperature change becomes large. This tendency is particularly remarkable in the case of a small fixing device.

[0009]

In the conventional fixing device,
Particularly in the case of a small device, it is difficult to keep the temperature of the fixing unit within a predetermined range, and if the fluctuation range is reduced, it is necessary to frequently perform on / off control of the halogen lamp that constitutes the heat source. There was an inconvenience that the life was shortened. According to the present invention, the fixing device is realized in which the rising time is shortened and the first copy can be quickly obtained (the invention of claim 1). Further, it is possible to realize a fixing device in which the temperature variation of the heat source is small and the life of the halogen lamp can be extended (the inventions of claims 2 to 5).

[0010]

According to a first aspect of the present invention, in a fixing device that fuses toner by heat energy to fix it on the surface of paper, the output (wattage) of the heat source is maintained at a required fixing temperature. It is more than twice the output required.

According to the invention of claim 2, in the fixing device of claim 1, two halogen lamps are provided.

According to a third aspect of the invention, in the fixing device of the second aspect, a switching means for switching the heat source and a temperature detecting means for detecting the temperature of the fixing device are provided, and the time from the standby time until the required fixing temperature is reached. Is configured to drive the heat source by 100% and, after reaching the required fixing temperature, switch the heat source equivalently to ½ or less by switching in a pulse shape.

According to the invention of claim 4, in the fixing device of claim 3, the frequency of the switching operation of the switching means is
It is configured to be 100 Hz or 120 Hz or less.

According to a fifth aspect of the present invention, in the fixing device according to the third aspect, when the temperature is raised from the standby state to the required fixing temperature, the temperature detecting means determines that the temperature has reached a predetermined temperature before reaching the required fixing temperature. When detected, the heat source is configured to be turned off.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the fixing device of the present invention will be described. Although this embodiment corresponds to the inventions of claims 1 to 5, the invention of claim 1 is the basic invention. According to the present invention, the fixing device is realized in which the rising time is fast and the time required to reach the usable state is as short as about 10 seconds (the invention of claim 1).

Further, it is possible to realize a fixing device having stable characteristics in which hunting does not occur due to temperature fluctuation (inventions 1 to 3 and 5). It is possible to realize a fixing device in which the temperature fluctuation is small and the life of a halogen lamp used as a heat source can be extended (the invention of claim 4).

First, in the fixing device, the reason why energy more than twice the energy for maintaining the required fixing temperature is given is that the waiting time that is permissibly permissible for obtaining the first copy (first copy) is about This is because it is said to be 10 seconds. As described above, the required fixing temperature of the fixing roller (heat roller) is 170 to 180 ° C. (equilibrium state), and the room temperature or the preheating state is around 80 ° C. in the standby state. Therefore, the temperature range to be increased is about 100 ° C. from the preheated state and about 150 ° C. from room temperature.

Usually, in order to raise the temperature of the apparatus for fixing a copy of 10 PPM by 100 ° C. for 10 seconds, it requires energy more than twice the heat capacity in the equilibrium state (the relationship between the heat capacity of the fixing apparatus and the loss at the time of fixing). ). If the theoretical basis is expressed by a relational expression, (temperature range to be raised) × (heat capacity of fixing device) = (electric power for full lighting of heater) × 10 (se
c).

Here, the heat capacity of the fixing device = C (F), the power for full lighting of the heater = W (I), and the power required for fixing =
If W (F) and the temperature range to be increased = 100 (° C.), the above relational expression can be expressed as follows. 100 (° C.) × C (F) = W (I) × 10 (sec) 10 × C (F) = W (I) In this case, C (F) and W (F) are Since the relation of is approximately 5 to 1, W (I)> 2 × W (F)
Should be set to.

Further, from the viewpoint of the life of the halogen lamp, it is desirable to limit the energy twice as much as the output required to maintain the required fixing temperature to the range of about 10 to 20% increase. Therefore, as a whole, energy of 2 to 2.4 times (about 8 seconds) is given, and preferably 2 to 2.2 times (about 9 seconds) from the viewpoint of life (claim 1 invention). .

In this case, in order not to affect the life of the halogen lamp, if two lamps are connected in parallel, the energy given to each lamp may be a rated value (the invention of claim 2). ). The conventional driving of the heat source is a method of switching the halogen lamp at a high frequency, so that the life of the lamp is shortened. A value such as 100 msec is set, and re-energization is not performed in a shorter time than that. The reason is that short-time switching operation by high frequency significantly deteriorates the life of the lamp.

FIG. 1 is a functional block diagram showing an embodiment of the essential structure of the fixing device of the present invention. Reference numerals in the figure are the same as those in FIG.
Is a ROM, 13 is a RAM, 14 is a timer, 15 is a triac, and 16 is an A / D converter.

The basic structure of the fixing device of the present invention is as follows.
Although it is similar to the conventional apparatus shown in FIG. 4, it is characterized in that the CPU 11 performs on / off control of the halogen lamp according to the flow shown in FIG. The A / D converter 16 converts the output of the thermistor 4, which is the temperature detecting means, into a digital signal to control the system.
The temperature information is given to 11. The fixing device of the present invention has the following features.

First, as described above, the halogen lamp 3 (heater) is heated by applying energy at least twice the required fixing temperature (Tf: equilibrium state). Second
In this case, two halogen lamps 3 are used and driven in parallel so that the life of the lamp is not adversely affected. During the subsequent heating, if the two lamps are appropriately switched and driven, the life can be extended. Thirdly, when two halogen lamps 3 are used, full lighting is performed at the time of start-up, but low output is given to the subsequent heating.

Fourth, after the required fixing temperature Tf is reached, when the temperature is lowered, for example, 100 msec,
Heating is performed with a pulse with a longer cycle than that of high frequency. Fifthly, the heating of the heater is stopped when the temperature reaches a predetermined temperature (Tp) which is equal to or lower than the required fixing temperature Tf, but the required fixing temperature Tf is reached due to the time lag characteristic of heating, so that no overshoot occurs.

FIG. 2 is a flow chart showing the main processing flow of the heat source on / off control in the fixing device of the present invention. In the figure, # 1 to # 10 represent steps, Tf represents a required fixing temperature, Tp represents a predetermined temperature equal to or lower than the required fixing temperature Tf, and t1 represents a timer set time.

When the heat source is turned on in the standby state, the heater (halogen lamp) is driven at the rated (100%) in step # 1. Next step #
In step 2, the temperature is monitored until it reaches a predetermined temperature Tp (where Tf> Tp) before reaching the required fixing temperature. This temperature Tp
Sets a value near the value at which overshoot does not occur at startup.

When it is detected in step # 2 that the temperature Tp has been reached, the heater is turned off in the next step # 3. Proceeding to step # 4, it is monitored whether the temperature of the heater has reached the required fixing temperature Tf or higher. Required fixing temperature T
When it is detected that f or more, next step # 5
Then, it is monitored whether or not the temperature is equal to or lower than the required fixing temperature Tf.

When it is detected that the temperature of the heater has become equal to or lower than the required fixing temperature Tf, the process proceeds to step # 6 and the timer is set. In the next step # 7, the heater is turned on. In step # 8, it is monitored whether the set time t1 has elapsed. This set time is set so that the heater is not turned off for such a short time as to adversely affect the life of the lamp.

When it is detected in step # 8 that the set time t1 has elapsed, the process proceeds to the next step # 9,
Turn off the heater. If the switch is not turned off in step # 10 (if not finished), the process returns to the previous step # 5 and the same process is performed. Step # 1
The above operation is repeated until it is detected that the switch is turned off at 0. When the switch is turned off, the flow of FIG. 3 is terminated.

FIG. 3 is a diagram showing an example of the relationship between the drive time and the change in the fixing temperature of the fixing device of the present invention. Reference numerals in the figure are the same as those in FIG. 5, and Tp indicates a predetermined temperature equal to or lower than the required fixing temperature Tf.

In the fixing device of the present invention, the halogen lamp 3 (heater) is heated by applying energy twice as much as the required fixing temperature (Tf: equilibrium state). As shown in. And
When the temperature reaches a predetermined temperature Tp that is equal to or lower than the required fixing temperature Tf, the drive output is turned off. However, the temperature of the halogen lamp 3 continues to rise and reaches the required fixing temperature Tf. After that, when the temperature of the halogen lamp 3 decreases, the drive output is turned on again, but the drive output in this case is 100 to 120, for example, 100 msec.
Pulses below Hz (commercial frequency). Therefore, the life of the lamp 3 is not affected, and heating with little temperature fluctuation is possible.

[0033]

In the fixing device according to the first aspect of the present invention, the output (wattage) of the heat source is set to at least twice (about 2.2 to 2.4 times) the output required to maintain the required fixing temperature. are doing. Therefore, it is possible to obtain the first copy in a short time of about 10 seconds that does not make the person feel sensibly long.

In the fixing device of claim 2, in the fixing device of claim 1, the halogen lamp used as a heat source is
This is connected in parallel. Therefore, the same effect as the fixing device according to the first aspect can be obtained without affecting the life of the lamp.

According to a third aspect of the present invention, in the fixing device according to the second aspect, the heat source is driven 100% for a period of time from the stand-by time until the required fixing temperature is reached, and after reaching the required fixing temperature, the pulse shape is applied. By switching to, the heat source is equivalently reduced to ½ or less. Therefore, even in a small-sized device having a small heat capacity, overhunting does not occur, driving with less temperature fluctuation of the heat source is possible, and the same effect as the fixing device of claim 2 can be obtained.

According to the fixing device of claim 4, in the fixing device of claim 3, the frequency of the switching operation of the switching means is set to 100 Hz or 120 Hz or less. Therefore, it is possible to avoid the shortening of the life of the halogen lamp, which is caused by driving a high-frequency heat source as in the related art, and to obtain the same effect as that of the fixing device of claim 3.

According to a fifth aspect of the fixing device, in the fixing device of the third aspect, when it is detected that the temperature has reached a predetermined temperature before reaching the required fixing temperature at the time of rising from the standby state to the required fixing temperature, The heat source is off. Therefore, similar to the fixing device of the third aspect, an effect that overhunting does not occur can be obtained.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of a main part configuration of a fixing device of the present invention.

FIG. 2 is a flowchart showing a main processing flow of heat source on / off control in the fixing device of the present invention.

FIG. 3 is a diagram showing an example of a relationship between a drive time and a change in fixing temperature of the fixing device of the present invention.

FIG. 4 is a block diagram showing a configuration example of a conventional fixing device that fuses toner by heat energy and fixes it on the surface of paper.

FIG. 5 is a diagram showing an example of a relationship between a driving time and a change in fixing temperature of a conventional fixing device using a driving method.

[Explanation of symbols] 3 halogen lamp 4 thermistor 5 commercial frequency power supply 11 CPU 12 ROM 13 RAM 14 timer 15 triac 16 A / D converter

Claims (5)

[Claims] 1. In a fixing device that fuses toner by heat energy to fix it on the surface of paper, the output (wattage) of the heat source is at least twice the output required to maintain the required fixing temperature. Fixing device characterized by. 2. The fixing device according to claim 1, wherein the heat source is a halogen lamp, and two halogen lamps are provided. 3. The fixing device according to claim 2, further comprising a switching means for switching the heat source, and a temperature detecting means for detecting the temperature of the fixing device, wherein the time from the stand-by to the required fixing temperature is the heat source. Drive 100%, and after reaching the required fixing temperature,
A fixing device characterized in that the heat source is equivalently reduced to ½ or less by switching in a pulsed manner. 4. The fixing device according to claim 3, wherein the switching operation of the switching means has a frequency of 100.
A fixing device having a frequency of Hz or 120 Hz or less. 5. The fixing device according to claim 3, wherein when the temperature detecting means detects that the temperature has reached a predetermined temperature before reaching the required fixing temperature, at the time of rising from the standby state to the required fixing temperature. , A fixing device characterized by turning off a heat source.