KR20060119353A - Fusing temperature control method for image forming apparatus - Google Patents

Abstract

A method of controlling a fixing temperature of an image forming apparatus is provided to reduce a first page output time and prevent poor initial fixing. A method of controlling a fixing temperature of an image forming apparatus measures a decrease temperature of a heating roller in a printing operation(S150) and increases a rotation temperature at which the heating roller rotates with a press roller by a value corresponding to the measured decrease temperature(S170). The decrease temperature is measured using a temperature sensor attached to the heating roller and calculated from a difference between a temperature at the time when the temperature of the heating roller starts to fall and a temperature at the time when the temperature of the heating roller starts to rise again.

Description

Fusing temperature control method for image forming apparatus

1 is a view schematically showing a fixing unit of an image forming apparatus for implementing a first embodiment of the present invention;

Figure 2 is a graph showing the temperature change of the heating roller in the state before the rotational temperature of the heating roller is corrected,

3 is a flowchart of a fixing temperature control method according to a first embodiment of the present invention;

4 is a flow chart showing in detail the heating roller rotation temperature correction step of FIG.

5 is a view schematically showing a fixing unit of an image forming apparatus for implementing a second embodiment of the present invention, and

Figure 6 is a graph showing the temperature change of the heating roller after the rotation temperature correction of the fixing unit according to the first and second embodiments of the present invention.

<Description of the symbols for the main parts of the drawings>

One; A fixing unit 10; Heating roller

11; Heating roller temperature sensor 20; Press Roller

31; A temperature sensor 32 in the fixing unit; Fusing unit external temperature sensor

The present invention relates to an image forming apparatus, and more particularly, to a fixing temperature control method of an image forming apparatus.

In general, the fixing unit of the image forming apparatus includes a heating roller and a pressure roller that rotates in engagement with the heating roller. The paper on which the visible image is transferred is heated by a heating roller, and the visible image is fixed to the paper by being pressed by the pressure roller.

By the way, the heating roller has a heating source therein, the pressure roller is rotated in close contact with the heating roller at a constant pressure, there is no separate heating means is built. Therefore, when the image forming apparatus starts to operate and the heated heating roller starts to rotate, the heat of the heating roller is transferred to the pressure roller in a relatively low temperature state, and the surface temperature of the heating roller decreases instantaneously. .

When the temperature of the heating roller is temporarily lowered in this manner, an image fixing failure may occur because the surface of the printing paper on which the visible image is actually transferred cannot be heated with sufficient heat. In addition, when the temperature of the heating roller falls below the temperature required for fixing, fixing stops until the heating roller reaches the fixing temperature, which increases the first page output time (FPOT). .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a method for controlling the fixing temperature of an image forming apparatus which can shorten the first page printing time and prevent the initial fixing failure.

In the fixing temperature control method of the image forming apparatus according to the present invention for achieving the above object, by measuring the falling temperature (Ts) of the heating roller during the printing operation, the heating roller starts to rotate with the pressure roller The rotation temperature Tr may be corrected to a value Td that is increased by the measured falling temperature Ts.

According to the first embodiment of the present invention, the falling temperature (Ts) of the heating roller measures the temperature of the heating roller by using a temperature sensor attached to the heating roller, the time at which the temperature of the heating roller starts to fall It can be calculated from the difference between the temperature Ta and the temperature Tb at the time when the temperature decreases and then rises again.

According to the second embodiment of the present invention, the falling temperature (Ts) of the heating roller is a heating roller according to the temperature difference between the inside and outside of the fixing unit by using a temperature sensor installed in the inside and outside of the fixing unit, respectively. It can be calculated by estimating the temperature change of

In the method of estimating the temperature change of the heating roller in a proportional manner, the internal and external values are stored in a control unit by storing a value obtained through an experiment for measuring a change in the temperature value of the heating roller according to an internal temperature and an external temperature change of the fixing unit. It is preferable to estimate the temperature value of the heating roller stored in the controller according to the temperature information output from the temperature sensor as the current temperature of the heating roller.

On the other hand, the fixing temperature control method of the image forming apparatus according to a preferred embodiment of the present invention, the step of heating the heating roller to the rotation temperature (Tr) when a print command is output; When the heating roller reaches the rotation temperature Tr, heating the heating roller together with the pressure roller while heating to the fixing temperature Tf; Measuring a temperature change of the heating roller after the heating roller reaches the rotation temperature Tr, and calculating a falling temperature Ts when the temperature of the heating roller falls; And setting the correction rotation temperature Td by increasing the value of the rotation temperature Tr by the falling temperature Ts of the heating roller.

According to the present invention as described above, since the heating temperature of the heating roller is increased by the temperature difference between the heating roller and the pressure roller, even if heat of the heating roller is conducted to the pressure roller while the heating roller starts to rotate, Since it is not generated, it is possible to shorten the first page printing time, and to prevent the image fixing failure caused by the low initial fixing temperature.

Hereinafter, preferred first and second embodiments of the present invention will be described with reference to the accompanying drawings and a flowchart.

1 is a view schematically showing a fixing unit of an image forming apparatus for implementing the present invention, FIG. 2 is a graph showing a state in which a temperature drop appears in a heating roller at an initial stage of operation, and FIGS. 3 and 4 are FIGS. A flow chart illustrating a fixing temperature control method for compensating a temperature drop section of the apparatus.

As shown, the fixing unit of the image forming apparatus includes a housing 1, a heating roller 10, and a pressure roller 20.

The housing 1 forms an exoskeleton of the fixing unit and is rotatably installed in a state in which the heating roller 10 and the pressure roller 20 are engaged with each other.

The heating roller 10 has a heating source such as a halogen lamp installed therein to heat the fixing unit to a set fixing temperature Tf, and a heating roller temperature sensor 11 for measuring the temperature of the heating roller 10 is installed. .

The pressure roller 20 engages and rotates while being in close contact with the heating roller 10 at a predetermined pressure, and applies pressure to the printing paper P passing between the heating roller 10 and the pressure roller 20.

The fixing temperature control method of the image forming apparatus according to the present invention configured as described above will be described with the flowcharts of FIGS. 3 and 4.

When power is applied to the image forming apparatus, the controller drives the heating roller 10 to heat up to the specified warm-up temperature T1. The warm-up temperature T1 is set to a temperature lower than the fixing temperature Tf (about 100 degrees Celsius) so that the shape of the image forming apparatus is not deformed and the developer is not denatured. However, when the warm-up temperature T1 is too low, it takes a long time to heat the fixing roller 10 to raise the fixing unit to the fixing temperature Tf. In consideration of developer characteristics and the like, it is preferable to set the appropriate temperature (S110).

When the temperature of the fixing unit is raised to the warm-up temperature T1, the controller stops the driving of the heating roller 10 and intermittently heats the heating roller 10 to maintain the warm-up temperature T1 (S120).

When the image forming apparatus starts a printing operation (S130), the controller heats the heating roller 10 to a predetermined rotation temperature (Tr, heating roller rotate temperature, approximately 170 degrees Celsius) (S140).

When the heating roller 10 reaches the rotation temperature Tr, the control unit rotates the heating roller 10 together with the pressure roller 20, while heating the heating roller 20 to the fixing temperature (Tf, approximately 190 degrees Celsius) Heat. The reason for heating the heating roller 10 to the rotational temperature (Tr) in this manner is to rotate the heating roller 10 together with the pressure roller 20 in a state where the heating roller 10 is not sufficiently heated. Because it falls.

When the fixing unit is heated as described above, the visible image transferred to the printing paper passing between the heating roller 10 and the pressure roller 20 is fixed by the heat of the heating roller 10 and the pressure of the pressure roller 20. do.

On the other hand, the heating roller temperature sensor 11 measures the temperature of the heating roller 10 during the operation of the image forming apparatus and outputs the measured value to the control unit, and the control unit measures the heating roller measured by the heating roller temperature sensor 11. 10) stores the temperature of each time zone (S150).

Then, the control unit compares the temperature of the heating roller 10 measured by the heating roller temperature sensor 11 for each time zone, the heating roller 10 is heated to the rotation temperature (Tr), and together with the pressure roller 20 Determine whether or not the surface temperature is lowered while rotating (S160).

When the temperature drop of the heating roller 10 is sensed in step S160, the controller corrects the rotation temperature Tr of the heating roller 10 to the corrected rotation temperature Td (S170).

For example, it is assumed that the warm-up temperature T1 of the heating roller 10 is 100 degrees Celsius, the rotation temperature Tr at which rotation starts with the pressure roller 20 is 170 degrees Celsius, and the fixing temperature Tf is 190 degrees Celsius. On the other hand, the heating roller 10 is heated in a stationary state from 100 degrees Celsius, which is a warm-up temperature T1, to 170 degrees Celsius, which is a rotational temperature Tr, and then rotates together with the pressure roller 20, which is a fixing temperature Tf. Heated up to 190 degrees Celsius. When the heating roller 10 starts to rotate, the heat of the heating roller 10 is transferred to the pressure roller 20 while the surface temperature of the heating roller 10 decreases. Then, the control unit uses the temperature information of the heating roller 10 measured by the heating roller temperature sensor 11, the starting point (Ta) and the temperature starting point of the temperature reduction start point of the heating roller 10 rises after the temperature decrease stops ( Tb) is measured (S171) (S172), and the temperature difference thereof is calculated to obtain the falling temperature Ts (S173).

Ts = Ta-Tb

For example, as shown in Figure 2, if the temperature (Ta) of the temperature drop start point of the heating roller 10 is 170 degrees Celsius, the temperature Tb of the starting point rising after the temperature stops is 160 degrees Celsius, the falling temperature Ts is 10 degrees Celsius. As described above, when the falling temperature Ts is obtained, the controller sets the correction rotation temperature Td of the heating roller 10 to 180 degrees Celsius, which is increased by Ts from the initial rotation temperature Tr (170 degrees Celsius) (S174). .

Td = Tr + Ts

When the correction rotation temperature Td is set as described above, the control unit adjusts the set rotation temperature Tr at which the heating roller 10 starts rotation with the pressure roller 20 at the first 170 degrees Celsius. Td) Correct the calculated value to 180 degrees Celsius.

Then, if the image forming apparatus starts printing in the stationary state after the correction, the heating roller 10 is heated until reaching the corrected value of 180 degrees Celsius, and then rotates together with the pressure roller 20. do. When the rotational temperature (Tr) of the heating roller 10 is corrected as described above, even if the heating roller 10 is rotated in engagement with the pressure roller 20 in a relatively cold state, as shown in the graph shown in FIG. Immediately without, it can rise directly to the point of fixation temperature (Tf). This is because, since heat corresponding to the falling temperature Ts of the heating roller 10 is additionally generated in the heating roller 10, the heat generated in the additional heating roller preheats the pressure roller 20 to an appropriate level. .

In addition, since more heat is applied to the heating roller 10, the time for fixing the fixing unit to the fixing temperature Tf is shortened, so that the first page printing time of the image forming apparatus can be shortened.

In addition, since the sudden drop of the temperature of the heating roller 10 does not occur, it is possible to reduce an image fixing failure that may occur due to the low temperature of the fixing unit at the beginning of printing.

On the other hand, according to the second embodiment of the present invention, unlike the first embodiment, it is possible to correct the rotational temperature (Tr) of the heating roller 10 by installing a temperature sensor inside and outside the fixing unit.

That is, as shown in Figure 5, the heating roller 10 and the pressure roller 20 of the internal temperature sensor 31 and the fixing unit for measuring the internal temperature of the fixing unit without separately installing a separate temperature sensor A method of estimating the temperature change of the heating roller 10 and the pressure roller 20 by using an external temperature sensor 32 for measuring the external temperature and using the temperatures measured by the temperature sensors 31 and 32. to be.

In this case, since the temperature of the heating roller 10 is not directly measured, the precision may be inferior as compared with the first embodiment. However, the malfunction of the sensor compared to the case in which the temperature sensor is installed in the heating roller 10 operated while rotating. And since the failure rate is reduced, it is more excellent in terms of device reliability.

That is, the control unit measures the temperature change of the heating roller 10 according to the difference between the internal temperature of the fusing unit measured by the internal temperature sensor 31 and the external temperature of the fusing unit measured by the external temperature sensor 32 through experiments or the like. Store in

For example, if the internal temperature of the fixing unit is 180 degrees Celsius, and the external temperature is 40 degrees, the temperature of the heating roller 10 in this case is stored in advance through experiments, and the temperature of the heating roller 10 according to each temperature change. Find the value. Then, after this, even if a separate temperature sensor is not installed in the heating roller 10 installed in the fixing unit of the same specification, the internal temperature sensor 31 and the external temperature sensor (measuring the temperature inside and outside the fixing unit) 32) only the temperature of the heating roller 10 can be estimated.

When the temperature of the heating roller 10 is estimated as described above, the temperature of the heating roller 10 is sensed as described in the first embodiment through the estimated temperature, and the rotational temperature Tr of the heating roller 10 is detected. ) Is corrected by the correction rotation temperature (Td). Since the process is the same as in the first embodiment, duplicated description is omitted.

On the other hand, although not shown, as another embodiment of the present invention, by installing a temperature sensor only in the pressure roller 20, there may also be a method of controlling the temperature of the heating roller by only the temperature change of the pressure roller 20. The method is the same as in the first embodiment.

According to the present invention as described above, since the heating temperature of the heating roller is increased by the temperature difference between the heating roller and the pressure roller, even if heat of the heating roller is conducted to the pressure roller while the heating roller starts to rotate, Since it is not generated, it is possible to shorten the first page printing time, and to prevent the image fixing failure caused by the low initial fixing temperature.

While the invention has been described and illustrated in connection with preferred embodiments for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described. Rather, those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (5)

In the fixing unit temperature control method of an image forming apparatus comprising a heating roller and a pressure roller, Measures the falling temperature (Ts) of the heating roller during printing operation, and corrects the rotating temperature (Tr) at which the heating roller starts to rotate with the pressure roller to a value (Td) which is increased by the measured falling temperature (Ts). A fixing temperature control method of an image forming apparatus, characterized in that. The method of claim 1, wherein the falling temperature (Ts) of the heating roller, The temperature of the heating roller is measured using a temperature sensor attached to the heating roller, A method of controlling a fixing temperature of an image forming apparatus, characterized in that it is calculated by the difference between the temperature Ta at the time when the temperature of the heating roller starts to fall and the temperature Tb when the temperature rises again after the temperature decreases. The method of claim 1, wherein the falling temperature (Ts) of the heating roller, Fixing temperature control method of the image forming apparatus, characterized in that the temperature change of the heating roller in accordance with the internal and external temperature difference of the fixing unit by estimating the temperature change sensor installed in the inside and outside of the fixing unit, respectively, proportionally . The method of claim 3, wherein Method for estimating the temperature change of the heating roller in a proportional formula, Storing the value obtained through the experiment to measure the change in the temperature value of the heating roller according to the internal temperature and the external temperature change of the fixing unit, the heating stored in the control unit according to the temperature information output from the internal and external temperature sensor A fixing temperature control method of an image forming apparatus, characterized in that the temperature value of the roller is estimated as the current temperature of the heating roller. In the fixing temperature control method of the image forming apparatus including a heating roller and a pressure roller, Heating the heating roller to a rotation temperature (Tr) when a print command is output; When the heating roller reaches the rotation temperature Tr, heating the heating roller together with the pressure roller while heating to the fixing temperature Tf; Measuring a temperature change of the heating roller after the heating roller reaches the rotation temperature Tr, and calculating a falling temperature Ts when the temperature of the heating roller falls; And And setting a corrected rotation temperature (Td) by increasing the value of the rotation temperature (Tr) by the falling temperature (Ts) of the heating roller.

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