JP2021056322A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that can improve the accuracy in detecting dew condensation compared with before.SOLUTION: A fixing device has a heat source 3, a fixing member 1, a pressure member 2, infrared temperature detection means 4 that detects infrared rays generated from a surface of the fixing member to measure temperature, and dew condensation means for the infrared temperature detection means. The dew condensation detection means detects dew condensation in the infrared temperature detection means 4 after the lapse of a predetermined time within 10 seconds from the start of lighting of the heat source. The fixing device has the other temperature detection means than the infrared temperature detection means 4 that detects the temperature of the surface of the fixing member or the surface of the pressure member; when the difference between an output temperature from the infrared temperature detection means 4 and an output temperature from the other temperature detection means exceeds a threshold, the fixing device may reduce output from the heat source 3, stop the lighting of the heat source 3, or drive the fixing member 1 and the pressure member 2 while lighting the heat source 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fixing device and an image forming device.

Conventionally, a fixing device having a heat source, a fixing member, a pressurizing member, an infrared temperature detecting means for detecting infrared rays generated from the surface of the fixing member and measuring the temperature, and a dew condensation detecting means for the infrared temperature detecting means has been known. Has been done. For example, in Patent Document 1, when the detection temperature difference between the infrared temperature sensor and the thermistor, which detects the temperature at a slightly different position in the center of the fixing roller, is larger than the predetermined difference, it is determined that dew condensation is formed, and the thermistor controls the lighting for a predetermined time. If this state continues, an alarm is issued or the power supply to the heater is cut off. Further, in Patent Document 2, when the temperature / humidity detecting means detects that the inside of the image forming apparatus has a temperature / humidity predetermined as a range in which the surface of the infrared temperature detecting means is dewed, the recording paper is run. It is stated that the prohibition is prohibited.

However, there was room for improvement in the accuracy of dew condensation detection.

The present invention has a fixing member, a pressure member, and an infrared temperature detecting means for detecting infrared rays generated from the surface of the fixing member or the surface of the pressure member and measuring the temperature in order to solve the above problems.
After a lapse of a predetermined time within 10 seconds from the start of lighting of the heat source, the relationship between the output of the infrared temperature detecting means and the output of the surface temperature detecting means of another fixing member or pressure member other than the infrared temperature detecting means, or The relationship between the output of the infrared temperature detecting means or the temperature detecting means for detecting the vicinity temperature of the infrared temperature detecting means and the output of the outside air temperature detecting means, or the output of the infrared near temperature detecting means and the output of the outside air temperature detecting means. When any of the relationship between the output of the outside air humidity detecting means and the output of the outside air humidity detecting means satisfies a predetermined relationship, the heat source is continuously lit, or the fixing member and the pressurizing member are driven while the heat source is lit. It is characterized in that it selects whether to reduce the output of the heat source or stop lighting the heat source.

According to the present invention, the accuracy of detecting dew condensation can be improved as compared with the conventional case.

Front view around the fuser of the image forming apparatus. Explanatory drawing of fixing roller. Explanatory drawing of temperature change at the time of sudden change of environmental temperature when machine is de-energized. The graph which shows the example of the time change of the outside temperature and the thermopile temperature at the environment temperature when the machine is not energized. The graph which shows the example of the fixing roller temperature change at the time of start-up at the time of abrupt change of the environmental temperature. A flowchart showing control of the start-up operation when dew condensation is detected on the thermopile. A relationship diagram that detects the dew condensation status from the temperature difference between the inside and outside of the machine and the relative humidity inside the machine. Psychrometrics. Explanatory drawing of the temperature which detects the dew condensation state from the ratio of the amount of temperature rise for a predetermined time of a central thermopile and an end thermistor. The figure which shows the relationship between the temperature rise ratio of a thermopile and a thermistor for a predetermined time, and the thermopile reading value and the actual temperature temperature difference after a start-up. Flow chart of control to detect the dew condensation situation from the temperature difference between the inside and outside of the machine and the relative humidity inside the machine. Flow chart of start-up control that detects dew condensation by the temperature rise ratio at the central end. Explanatory drawing at the time of dew condensation elimination operation. Flow chart of control to perform dew condensation reduction operation. The graph which shows the change of the thermopile temperature reading value and the fixing R center actual temperature at the time of performing a dew condensation reduction operation. Explanatory drawing of thermopile part and outside temperature change at the time of dew condensation elimination operation. The graph which shows the relationship between the dew condensation elimination time and the thermopile part temperature temperature rise amount (y). A graph showing the relationship between the thermopile temperature and the outside atmosphere temperature after the dew condensation elimination operation. The flowchart of the dew condensation reduction confirmation method # 1. The flowchart of the dew condensation reduction confirmation method # 2. The flowchart of the dew condensation reduction confirmation method (3). The graph of the thermopile temperature change example during the last 30s of the dew condensation reduction operation. A graph showing the relationship between the minimum thermopile temperature during the last 30 seconds of the dew condensation reduction operation and the thermopile temperature reading / actual temperature difference after the heater is turned on. The flowchart of the concrete example of the dew condensation reduction confirmation method part 2. A flowchart of a control method that performs a dew condensation elimination operation after detecting the dew condensation situation. A flowchart of another control method that performs a dew condensation elimination operation after the dew condensation status is detected. The schematic block diagram of an example of an image forming apparatus. Configuration example of the electrical component of the fixing device.

An embodiment in which the present invention is applied to a fixing device for fixing a toner image on paper by heating and pressurizing will be described. This fixing device detects the temperature with a thermopile, which is an infrared temperature detecting means. FIG. 1 is a front view showing a schematic configuration around a fuser of an image forming apparatus having a fuser that detects the temperature of a fixing roller with a thermopile. FIG. 2 is a right side view showing the fixing roller of the fixing device.

The fuser is a roller fuser in which the pressurizing roller 2 is pressed onto the fixing roller 1 having a built-in heater 3, and the paper 6 is conveyed in the direction indicated by the arrow. In FIG. 1, the frame surrounding the fixing roller 1 and the pressurizing roller 2 is the fixing device case 170a, and the frame surrounding the entire frame is the image forming apparatus case 100a. The temperature of the fixing roller 1 is detected by the thermopile 4. The thermopile 4 is attached to the outside of the fixing device case 170a in the image forming apparatus, and measures the temperature of the fixing roller in a non-contact manner.

As shown in FIG. 2, the heater 3 includes a central heating heater 3a located at the center in the axial direction of the fixing roller and end heating heaters 3b located at both ends in the axial direction of the fixing roller. The central heater 3a is controlled based on the detection temperature at the central portion in the axial direction shown by 10 in the figure, which is detected by the thermopile 4 in a non-contact manner. The end heater 3b is controlled by detecting the temperature by a contact-type end thermistor 9 provided in the non-paper-passing region.

As shown in FIGS. 1 and 2, the thermopile 4 is arranged in the center of the fixing roller 1 in the axial direction in a non-contact manner, and the contact-type end thermistor 9 is provided in the non-passing portion of the end to provide a temperature detection unit. It is possible to perform stable temperature detection by avoiding the adhesion of foreign substances such as toner and paper dust to the surface over time. Further, as shown in FIG. 1, an in-flight temperature detector 11 and an in-flight humidity detector 12 for detecting the temperature and humidity of the thermopile portion where the thermopile 4 is arranged may be provided. Further, the external temperature detector 13 and the external humidity detector 14 may be provided.

In the illustrated example, the in-flight humidity detector 12 and the in-flight temperature detector 11 are arranged in this order above the thermopile portion. Further, below the thermopile portion, an external temperature detector 13 and an external humidity detector 14 are provided in this order. The outside temperature detector 13 and the outside humidity detector 14 are installed at the outside air intake port of the image forming apparatus case 100a, and measure the temperature and humidity of the outside air. The dew condensation detecting means can be configured as described later by using the end thermistor 9 and the inside / outside temperature / humidity detectors (11, 12, 13, 14).

FIG. 3 is an explanatory diagram of a temperature change when the environmental temperature suddenly changes when the power is not supplied. When the environmental temperature rises sharply from the state where the entire image forming apparatus is left in a low temperature environment in a non-energized state, the outside atmosphere temperature Ta rises at the temperature rise gradient shown in the figure, as shown by the solid line. At this time, the temperature inside the machine, specifically, the ambient temperature of the thermopile portion (hereinafter referred to as the temperature of the thermopile portion) T2 does not rise following the outside atmosphere temperature Ta as shown by the broken line.

FIG. 4 shows an example of changes in the outside atmosphere temperature Ta and the thermopile portion temperature T2 over 8 hours when the environmental temperature in FIG. 3 suddenly changes. Even if the outside atmosphere temperature Ta changes from −30 ° C. to 23 ° C. in 8 hours, the thermopile portion temperature T2 only rises to 10 ° C.

FIG. 5 shows fixing after the power is turned on when the power is turned on (“energized” in FIG. 3) and the start-up operation is performed when one hour has passed since the environmental temperature suddenly changed when the power was not turned on in FIG. An example of a change in roller temperature is shown. The horizontal axis shows the elapsed time (seconds, s) after startup. The vertical axis on the left is the temperature scale (° C) of the temperature T1 corresponding to the readings of the fixing roller center actual temperature (hereinafter referred to as the fixing roller center actual temperature) T0 and the thermopile 4, and the duty (%) of the center heating heater 3a. ). The vertical axis on the right side is the temperature scale of the outside atmosphere temperature Ta and the thermopile temperature T2. In addition to the above-mentioned changes in various temperatures T0, T1, Ta, and T2, the target temperature T1'at the center of the fixing roller axial direction and the duty of the central heating heater 3a in the fixing roller are also shown. The actual temperature T0 at the center of the fixing roller is the temperature at the center of the fixing roller in the axial direction measured by an experiment using a thermocouple.

The thermopile 4 detects the temperature at a low temperature due to dew condensation as shown in the portion 5 of FIG. As shown by the white arrow A in FIG. 5, there is a 90 deg temperature difference between the temperature corresponding to the thermopile temperature reading (hereinafter referred to as the temperature reading) T1 180 ° C. and the actual temperature at the center of the fixing roller T0 270 ° C. Since the detection is low as described above, the heater is excessively turned on when trying to maintain the target temperature, and as shown in FIG. 5, the actual temperature T0 at the center of the fixing roller becomes as high as 270 ° C. or higher. This caused damage to the fixing member (welding of the fixing roller and the pressure roller).

As shown in FIG. 3, the thermopile temperature T2 rises as time elapses after the abrupt change in the environmental temperature, and the amount of dew condensation accompanying the start-up operation decreases as the start-up operation is delayed. To do. Therefore, as the start-up operation is delayed, the temperature difference between the thermopile temperature reading value T1 after the start and the actual temperature T0 at the center of the fixing roller (hereinafter referred to as the thermopile temperature reading value / actual temperature temperature difference) becomes smaller, and the center of the fixing roller becomes smaller. It is possible to suppress the actual temperature T0 from becoming excessively high, and it is possible to avoid damage to the fixing member. However, it has been confirmed that the damage to the fixing member due to the thermopile dew condensation cannot be resolved without waiting for about 2 hours (2 hr) after the transition of the environmental temperature.

A first embodiment for solving this problem will be described. This embodiment is a control method for stopping the operation in order to prevent damage to the fixing member when a thermopile dew condensation situation that may cause a problem is detected. FIG. 6 is a flowchart of the control. This is executed when the fixing device power is turned on (energization starts), such as after the power of the image forming device is turned on. First, the start-up operation is performed for a predetermined time (S601), then the dew condensation state is detected (S602), and when the dew condensation state in which a problem occurs (S602 / Y) is detected, an abnormal stop (heater lighting stop) is performed. If the dew condensation state that causes a problem is not detected (S602 / N), the start-up operation is continued.

Two methods will be described for detecting the dew condensation situation.
(1) Method of detecting from the temperature difference between the inside and outside of the machine and the relative humidity inside the machine FIG. 7 shows the relationship between the temperature difference inside and outside the machine related to dew condensation and the relative humidity inside the machine. The vertical axis shows the difference between the ambient temperature outside the machine detected by the outside temperature detector 13 in FIG. 1 and the thermopile temperature T2 detected by the inside temperature detector 11. The horizontal axis shows the relative humidity of the atmosphere of the thermopile portion detected by the in-flight humidity detector 12 of FIG.

Under the condition that the outside temperature is 20 ° C, the environment where the temperature difference between the inside and outside of the machine is different is prepared, and the environment of various relative humidity is prepared in each environment, and the fixing member is damaged when the fixing is started. The result of examining the presence or absence of is shown. The dots in □ are on the boundary of the presence or absence of dew condensation under the condition that the outside temperature is 20 ° C. The ◯ dot indicates that the fixing member is not damaged, and the × dot indicates that the fixing member is damaged.

In FIG. 7, the solid line L71 is a boundary line indicating the presence or absence of dew condensation under the condition that the outside temperature is 20 ° C, and is represented by the following (Equation 1) (unit: inside / outside temperature difference (deg), inside / outside relative humidity (unit: relative humidity inside the machine). %)).
Temperature difference between inside and outside the machine = -0.3 * Relative humidity inside the machine +27 ... (Equation 1)

This boundary line is derived from a psychrometric chart as shown in FIG. 8 (% in the figure is relative humidity). The condition is set to 20 ° C, assuming a general office environment in winter when dew condensation is likely to occur. In the office environment (temperature 17-28 ° C ∧ humidity 40-70%: Industrial Safety and Health Act Office Hygiene Standards Regulations Article 5.3), the L71 line is almost unchanged. Only a deviation of about ± 1 to 2 ° C. occurs with respect to the L71 line at 20 ° C.

The broken line L72 is a line in which the thermopile temperature reading / actual temperature temperature difference at which the fixing member is damaged is 50 deg or more, and is represented by the following (Equation 2). This broken line L72 is obtained from the experimental results shown in FIG. If a small amount of dew condensation occurs, a small amount of false detection of temperature will result in damage, but damage will occur only at the point where the difference between the thermopile and the actual temperature is 50 deg (the x plot on L72). Above that, there was a high probability of damage. This is true even when the outside temperature is different from 20 ° C. because, as described above, if the office environment temperature is used, the line where dew condensation occurs is almost the same, and the dew condensation level on the shifted L72 line is almost the same.

In this device, when the thermopile temperature reading / actual temperature temperature difference is 50 deg or more, the central actual temperature T0 of the fixing roller becomes 270 ° C. or more, and the fixing member is damaged.
Temperature difference between inside and outside of the machine = -0.3 * Relative humidity inside the machine +35 ... (Equation 2)
Therefore, if the temperature difference between the inside and outside of the machine is> -0.3 * relative humidity inside the machine +35, the fixing member will be damaged and the heater will stop lighting. In order to suppress the occurrence of high temperature offset, the heater lighting is stopped in the region above the boundary line between (Equation 1) and (Equation 2).

(2) Method of detecting from the temperature rise ratio (temperature rise gradient ratio) between the thermopile and the thermistor for a predetermined time The thermopile detects when dew condensation occurs at a lower temperature, whereas the thermistor detects dew condensation (temperature is detected by the resistance change due to temperature). Even if it does, the temperature is not falsely detected. Focusing on this point, we examined a method to detect the dew condensation situation by comparing the detected temperatures of both.

FIG. 9 shows the central thermopile 4 at startup in the fuser configuration shown in FIGS. 1 and 2, that is, the configuration in which the temperature is detected by the thermopile 4 at the center in the axial direction and the temperature is detected by the thermistor 9 at the end in the axial direction. An example of the temperature rise characteristic L91 of the above and the temperature rise characteristic L92 of the end thermistor 9 is shown. After the start-up start t0, first, the waiting time Ta is waited until the temperature rising gradients ΔTc and ΔTs are stabilized, and then the temperature rising amount for a predetermined time (heating amount detection time Tb) is detected. The waiting time Ta and the temperature rise detection time Tb are selected so as to satisfy the following conditions.

-In order to prevent damage to the fixing device, it is necessary to control the heater lighting (output reduction, lighting stop, etc.) before the temperature at which the fixing device is damaged (270 ° C in this device) is reached. The total time of the temperature rise detection time Tb is set within 15 seconds at the longest. Considering the gradient of the temperature rise curve, it is preferably within 10 seconds, and further preferably within 7 seconds in consideration of the variation in the temperature of the in-machine parts at the start of lighting the heater.

-Since it takes 3 to 5 seconds for the temperature rise gradient to stabilize, the waiting time Ta was set to 3.6 seconds in the evaluation.
-The temperature rise detection time Tb can be arbitrarily determined within the range that satisfies the above, and it is preferable to set it short from the viewpoint of power consumption. It was set to 1.2 seconds.

FIG. 10 shows the ratio of the temperature rise amount of the central thermopile 4 (the temperature rise amount corresponding to the change in the thermopile reading value) and the temperature rise amount of the end thermistor 9 at the temperature rise detection time Tb (hereinafter, the center end temperature rise temperature). It is a graph which shows an example of the relationship between a quantity ratio) and a thermopile temperature reading value / actual temperature temperature difference. The temperature rise ratio at the center end of the vertical axis is the ratio of ΔTc and ΔTs shown in FIG. 9, ΔTc / ΔTs, and the center when the thermopile temperature reading / actual temperature temperature difference on the horizontal axis is 0 (without condensation). It is shown as a standardized value with the end temperature rise ratio A as 1. The thermopile temperature reading and actual temperature temperature difference on the horizontal axis correspond to the degree of dew condensation.

The results are shown when the fixing device for various dew condensation conditions is detected by setting the waiting time Ta = 3.6 s and the temperature rise detection time Tb = 1.2 s. The larger the thermopile temperature reading / actual temperature temperature difference on the horizontal axis, the greater the amount of dew condensation, and the smaller the ratio of the temperature rise at the center end of the vertical axis, the lower the right.

Condensation occurs under the condition that the thermopile temperature reading / actual temperature temperature difference on the horizontal axis of FIG. 10 is larger than 0 deg, but the fixing member may be damaged if the thermopile temperature reading / actual temperature temperature difference is 50 deg or more. Therefore, the normalized value of the temperature rise ratio at the middle end of the vertical axis of FIG. 10 corresponding to the temperature rise ratio B at the center end where the thermopile temperature reading / actual temperature temperature difference, which is a condition for causing damage to the fixing member, is 50 deg or more. Damage to the fixing member can be prevented by stopping the abnormality detection (stopping the heater lighting) at a B / A of 0.75 or less. Instead of the threshold condition of the dew condensation condition indicated by the arrow A10 that the thermopile temperature reading value / actual temperature temperature difference is 50 deg or more, the threshold condition of the dew condensation condition indicated by the arrow B10 that the standardization of the middle end temperature rise ratio is 0.75 or less is used. It is used to prevent damage to the fixing member.

If the temperature difference is 40 deg or more and the image quality of the high temperature offset is poor, the abnormality detection is stopped when the standardized value B / A of the temperature rise ratio at the middle end for 1.2 s is 0.8 or less (heater). By performing the operation (stop lighting), it is possible to suppress the occurrence of poor image quality due to the high temperature offset.

Based on the above results, the control method reflecting the dew condensation status detection method is shown in FIGS. 11 and 12.
11 and 12 show the method of detecting the dew condensation condition (S602) in the control method of FIG. 6 from (1) the temperature difference between the inside and outside of the machine and the relative humidity inside the machine, (2) the thermopile, and the predetermined time of the thermistor. This is an example of adopting a method of detecting from the temperature rise ratio (heat temperature gradient ratio) of.

Specifically, in the control of FIG. 11, whether or not the detection of the dew condensation state (S112) is equal to or greater than the line represented by (Equation 1), that is, whether or not the next (Equation 1)'is satisfied. It is determined whether or not there is an abnormal dew condensation situation that leads to damage to the fixing member.
Temperature difference between inside and outside of the machine> = -0.3 * Relative humidity inside the machine +27 ・ ・ ・ (Equation 1) ´
However, ">=" represents the above.
Further, in the control of FIG. 12, the detection of the dew condensation state (S112) is performed by the threshold value B9 of FIG. 10, that is, the normalized value B of the middle end temperature rise ratio is the central end temperature rise ratio A when there is no dew condensation. Whether or not it is 0.8 times or less determines whether or not there is an abnormal dew condensation condition that leads to the occurrence of poor image quality of the high temperature offset. Depending on whether or not it is 0.75 times or less, it may be determined whether or not there is a dew condensation state that leads to damage to the fixing member, and when such an abnormal dew condensation state is determined, the lighting of the heater may be stopped. ..

As described above, by using the control method of the first embodiment, it is possible to prevent the fixing member from being damaged and to prevent the occurrence of high temperature offset. In the example described with reference to FIG. 10, the ratio of the amount of temperature rise is used, but the difference in the amount of temperature rise may be used. In each case, it is possible to grasp the difference in the amount of temperature rise that corresponds to the dew condensation situation. Further, the difference in the main temperature between the thermopile and the thermistor may be grasped not by the amount of temperature rise but by the difference or ratio between the two. In each case, the threshold to be used can be determined experimentally.

Next, the second embodiment will be described. In the first embodiment, the operation is to detect the dew condensation state, stop the abnormality detection (stop the heater lighting) under the condition that there is a concern about damage to the fixing member, and wait until the dew condensation disappears. In this case, it was necessary to wait for about 2 hours as described above. In the present embodiment, in order to shorten the waiting time, the dew condensation reduction operation is performed to shorten the waiting time until the dew condensation is reduced.

FIG. 13 is an explanatory diagram of the dew condensation reduction operation. In consideration of dew condensation on the portion 5 of the thermopile 4, the fixing roller 1 is heated and idled while the heater 3 is turned on so as to maintain the target temperature of the fixing roller 1 that does not damage the fixing member. The heater is continuously lit while releasing the heat of the fixing roller 1 to the pressurizing roller 2, and the atmospheric temperature of the thermopile portion is raised to increase the saturated water vapor amount and reduce the relative humidity of the atmosphere of the thermopile portion. This is an operation of reducing dew condensation.

FIG. 14 is a flowchart of the control. This is executed when the fixing device power is turned on (energization starts), such as after the power of the image forming device is turned on. First, the start-up operation is performed for a predetermined time (S141), then the dew condensation situation is detected (S142), and when the dew condensation state in which a problem occurs (S142 / Y) is detected, the dew condensation reduction operation (S143) is performed until the predetermined time elapses. (S144 / Y) is executed. Then, after the dew condensation reduction operation is executed for a predetermined time, it is determined whether or not the dew condensation is reduced (S145).

If the dew condensation is reduced (S145 / Y), the start-up operation is started again (S141). If the dew condensation is not reduced (S145 / N), the heater is stopped on as if an abnormality has been detected (S147). If the dew condensation state that causes a problem is not detected in the detection of the dew condensation state after the start-up operation for a predetermined time (S142 / N), the start-up operation after the fixing device power is turned on is continued (S146).

The start-up operation of S141 and S142 for a predetermined time and the detection of the dew condensation state can be performed in the same manner as in the control of FIG. That is, the start-up operation and the dew condensation state detection method for a predetermined time described with reference to FIGS. 7 to 12 can be used.

FIG. 15 shows changes in the thermopile temperature reading and the actual temperature when the dew condensation reduction operation was performed. The horizontal axis and the vertical axis on the left side are the same as in FIG. That is, the horizontal axis indicates the elapsed time (seconds, s) after the start-up. The vertical axis on the left side is the temperature scale (° C) of the actual temperature T0 at the center of the fixing roller and the reading T1 of the thermopile 4, and the duty (%) of the central heater 3a. In addition, in FIG. 16, the vertical axis on the left side is also the temperature scale of the outside atmosphere temperature Ta and the thermopile portion temperature T2. Further, the target temperature T1'at the center in the axial direction of the fixing roller and the duty of the central heating heater 3a in the fixing roller are also shown. The actual temperature T0 at the center of the fixing roller is the temperature at the center of the fixing roller in the axial direction measured by an experiment using a thermocouple.

The time t15 indicates the time when the dew condensation abnormality is detected. Since it is after the startup for a predetermined time after the power is turned on, for example, when the waiting time Ta = 3.6 s and the temperature rise amount detection time Tb = 1.2 s are set and the detection is performed as in the first embodiment. Is the time point when 4.8 seconds have passed since the power was turned on. From this time t14, the dew condensation reduction operation is performed for time z (s), for example, 580 s. After the dew condensation reduction operation was started, the thermopile temperature reading T1 was about 120 ° C., the actual temperature T0 was about 180 ° C., and there was a temperature difference of about 60 deg. Condensation is reduced as it approaches the actual temperature T0 of the fixing roller (see the area marked with a circle A15). The thermopile temperature T2 and the outside atmosphere temperature Ta at that time are shown below, but the thermopile temperature T2 has risen to about the outside atmosphere temperature Ta + 20 deg (see the area marked with a circle B15).

During the dew condensation reduction operation, the target temperature is set to 120 ° C so that the actual temperature is 230 ° C or lower, thereby preventing damage to the fixing member. Further, the central heater reduces the lighting of the heater by suppressing the lighting duty to a maximum of 50%. By setting the target temperature during the dew condensation reduction operation higher than 120 ° C, it can be recovered in a shorter time, but the fixing device is damaged when the actual temperature is 270 ° C, and in the dew condensation state. Since a measurement error of about 90 deg can occur, the target temperature is preferably 180 ° C or less at the maximum. As a result of performing the dew condensation reduction operation, when it is determined that the dew condensation has been reduced or eliminated to an allowable extent and the start-up operation is started again, the central heater up to that point is turned on as shown in FIG. The duty may be released from suppressing the duty to max 50% and may be set to max 50%. That is, the output of the heat source may be increased as compared with that during the dew condensation reduction operation.

FIG. 16 shows the relationship between the dew condensation reduction operation time, the amount of temperature rise in the thermopile portion, and the outside temperature. In order to reduce dew condensation, it is necessary to raise the thermopile temperature T2 to x (deg) or more with respect to the outside atmosphere temperature Ta, and by rotating the fixing roller 1 for a predetermined time z (s), the thermopile temperature T2 Rise by y (deg). Therefore, when the temperature is raised from the temperature T3 such that the temperature (ex 25 ° C.) − (y−x)> T3 after the temperature rise of the environmental temperature, the dew condensation cannot be eliminated even if the rotation is performed for a predetermined time z (s). Therefore, in such a case, after performing the dew condensation reduction operation for a predetermined time, the dew condensation reduction is confirmed, it is determined that there is an abnormality (path reduction is insufficient) (S135 / N), and the heater lighting is stopped (S137). Become. This is the condition (S135 / N) for stopping the abnormality detection by the control method shown in FIG.

In FIG. 17, the horizontal axis represents the duration of the dew condensation reduction operation for a predetermined time z (s), and the vertical axis represents the temperature rise amount (deg) of the thermopile portion temperature T2. This is a plot of the relationship between the two when the dew condensation reduction operation is performed after the temperature changes. a1 is an environmental temperature change in which the temperature is raised from −10 ° C. to 25 ° C. at a heating rate of 20 deg per hour. If this is abbreviated and expressed as −10 ° C25 ° C20deg / h, the others are as follows. b1 is 10 ° C40 ° C20deg / h, c1 is -5 ° C23 ° C20deg / h, d1 is -30 ° C23 ° C8h (heated to 23 ° C in 8 hours), and e1 is -10 ° C10 ° C20deg /. h. As in the auxiliary line L16, the longer the dew condensation reduction operation time on the horizontal axis is, the larger the temperature rise (deg) of the thermopile portion temperature T2 on the vertical axis is after any change in the environmental temperature.

In FIG. 18, the horizontal axis represents the outside atmosphere temperature Ta (° C), and the vertical axis represents the thermopile temperature T2 (° C) after the dew condensation reduction operation, and the relationship between the two is plotted. The outside atmosphere temperature Ta on the horizontal axis is an experiment at four outside atmosphere temperatures Ta of 10 ° C, 23 ° C, 25 ° C, and 40 ° C. These four external atmosphere temperatures Ta correspond to the five environmental temperature changes a1 to e1 in FIG. There are a plurality of dots at an ambient temperature other than 10 ° C. As shown in FIG. 17, this is an experiment in which the dew condensation operation time is different, or an experiment is performed a plurality of times at the same time, and the thermopile portion temperature T2 on the vertical axis at that time is measured.

For the experiments corresponding to each plot, the following categories of thermopile temperature reading and actual temperature temperature difference are indicated by reference numerals a2, b2, and c2. That is, the thermopile temperature reading / actual temperature temperature difference is 50 deg or more for a2, 31 to 50 deg for b2, and 30 deg or less for c2. The auxiliary line L181 is a straight line of T2 = Ta, and the auxiliary line L182 is a straight line of T2 = Ta + 20 (deg). In this device, the thermopile temperature reading value / actual temperature temperature difference of 50 deg or more, in which the central actual temperature T0 of the fixing roller becomes 270 ° C. or higher and the fixing member is damaged, includes the auxiliary line L182 and does not occur in the upper part of the figure.

As described above, based on the confirmation results of FIGS. 17 and 18, the thermopile temperature T2> the outside atmosphere temperature Ta + 20 deg due to the dew condensation reduction operation of the rise y = 35 deg at the predetermined time z = 580 s idling indicated by the arrow X17 in FIG. Let (= x).

In FIG. 17, dew condensation is reduced when x = 20 deg or more, and referring to FIG. 15, when the thermopile portion temperature = environmental temperature + xy (° C.) or more, dew condensation can be reduced by the dew condensation reduction operation. If the increase y = 35 deg, the dew condensation can be reduced by the dew condensation reduction operation at an environmental temperature of −15 deg or more, and the dew condensation can be reduced in many large dew condensation states. If the temperature is lower than this, it is considered that there is no problem even if the device is operated to wait for the user by judging that the dew condensation is NG, and y = 35 deg is set as the threshold value. It was decided as a condition of how much dew condensation should be relieved by the dew condensation reduction operation.

As described above, according to the second embodiment, what had to wait for about 2 hr at the time of thermopile dew condensation in the first embodiment is reduced by performing a dew condensation reduction operation for about 10 minutes (= 580 s), and the machine is reduced. It became possible to start up.

A specific example of the dew condensation reduction confirmation (a135) performed at the end of the dew condensation reduction operation by the control method of FIG. 14 is shown in FIGS. 19, 20, and 21. Judgment is made from the temperature difference between the thermopile portion temperature T2 (internal temperature detector 11 in FIG. 13) and the external atmosphere temperature Ta (external temperature detector 13) shown in FIG. If the thermopile part temperature T2-external atmosphere temperature Ta> = 20 deg, the reduction is confirmed, and the reduction cannot be confirmed otherwise.

FIG. 20 shows that the thermopile temperature reading value T1 is equal to or higher than the predetermined temperature for a predetermined time (the reading value has started to increase) to confirm that the dew condensation shown in FIG. 15 has been reduced or eliminated and the thermopile portion temperature T2 has risen. That) is detected. A further specific example of this will be described later. FIG. 21 shows the dew condensation region of FIG. 7 by performing dew condensation reduction detection based on the output of each of the temperature detector 11 and the humidity detector 12 provided around the thermopile portion and the output of the external temperature detector 13. Alternatively, it is detected that the thermopile has come off from the damaged region of the fixing member having a temperature difference of 50 deg or more between the thermopile temperature reading value and the actual temperature, and the reduction of dew condensation is confirmed. Of these, FIG. 21 shows an example of the latter corresponding to (Equation 2).

The method of detecting the rise of the thermopile temperature reading value T1 described with reference to FIG. 20 (the rise of the thermopile temperature reading value T1 of FIG. 15) will be described with reference to FIGS. 22 and 23. An example of the change in the thermopile temperature reading T1 during the last 30 s of the dew condensation reduction operation 580 s shown in FIG. 22 is shown. Time t22 indicates the end time point of the dew condensation reduction operation. The auxiliary line T10 indicates the minimum temperature during the 30s, and the auxiliary line T11 indicates the target temperature. FIG. 23 shows the minimum value T10 of the thermopile temperature reading value T1 detected for the devices in various dew condensation states during the last 30 seconds, and the thermopile temperature reading value / actual temperature temperature difference after the heater lighting operation is performed after the dew condensation reduction operation. It shows the relationship between.

From FIG. 23, if the minimum temperature T10 during the last 30 seconds of the dew condensation reduction operation is 124 ° C or more (condition that the temperature has risen by 4 deg or more) with respect to the target temperature of 120 ° C of the thermopile 4 in the dew condensation reduction operation, then the heater It can be seen that the thermopile temperature reading value / actual temperature temperature difference after the start of the lighting operation is 40 deg at the maximum, and can be 50 deg or less. That is, it can be determined whether or not the dew condensation has been reduced depending on whether or not the minimum temperature T10 during the last 30 seconds of the dew condensation reduction operation has risen by 4 deg or more with respect to the target temperature of the thermopile 4. FIG. 24 shows the flow of the determination.

Next, the third embodiment will be described. The time for the dew condensation eliminating operation described in the second embodiment is further shortened. In the control method of the third embodiment, once the dew condensation reduction operation is started, the dew condensation reduction operation is confirmed at any time without continuing for a predetermined time, and when the dew condensation reduction operation is confirmed, the dew condensation reduction operation is terminated.

For example, in the temperature change of FIG. 15, the dew condensation elimination operation is performed for 580 s. For example, at 500 s, the thermopile part temperature (45 ° C.) becomes the outside temperature (25 ° C.) + 20 deg or more, so that the dew condensation elimination operation is performed. Even after the completion, it is possible to realize a start-up operation without damaging the fixing member.

FIG. 25 is a flowchart of a control example of the third embodiment. The difference from the control of FIG. 14 is as follows. In FIG. 14, after the dew condensation reduction operation is performed for a predetermined time (S144 / Y), the thermopile dew condensation reduction confirmation is performed (S145), and when the confirmation is confirmed, the start-up operation is resumed (S141). On the other hand, in FIG. 25, when the dew condensation reduction operation is started, the path reduction confirmation is repeated until the upper limit of the predetermined idling time is reached (S255 / Y), and when the confirmation is confirmed, the heating idling operation is terminated (S256). Then, the start-up operation is started again (S251). Then, in FIG. 25, when the upper limit of the predetermined idling time is reached without confirming the reduction of dew condensation (S255 / Y), the abnormality detection stop (heater lighting stop) is performed (S258).

For the confirmation of dew condensation reduction in this flowchart, the control methods shown in FIGS. 19, 20, 21, and 24 can be used. FIG. 26 is a flowchart when the confirmation method of FIG. 21 is used. By determining the detection of dew condensation elimination from the temperature difference between the inside and outside of the machine vs. the relative humidity inside the machine, the dew condensation elimination detection is performed at an early stage and the dew condensation elimination operation is terminated.

As described above, according to each embodiment, it is possible to start up in a short time without damaging the fixing member when the temperature rises sharply from the low temperature environment.

FIG. 27 shows an example of an image forming apparatus that can use the fixing apparatus according to each embodiment. The image forming apparatus 100 is an electrophotographic printer equipped with a photoconductor drum 110 as an image carrier. The photoconductor drum 110 is uniformly charged by the charging device 120, and exposure light such as a laser beam based on image information is applied to the photoconductor drum 110 from the writing device 130 to form an electrostatic latent image. The electrostatic latent image is developed by the developing device 140 to be a toner image. This toner image is fed from the paper feed cassette 150 by the paper feed roller 151, and is transferred by the transfer device 160 to the transfer paper P fed by the resist roller 152. The transfer paper on which the toner image is transferred is fixed by the fixing device 170 and then discharged onto the paper ejection tray 181 by the paper ejection roller 180. After the transfer, the photoconductor drum 110 is prepared for the next image after the residual toner and the like are removed by the cleaning device 190.

FIG. 28 is a configuration example of the electrical component of the fixing device 170. A thermopile 4, an end thermistor 9, an in-flight temperature detector 11, an in-flight humidity detector 12, an external temperature detector 13, an external humidity detector 14, and the like are connected to the control device 200 of the fixing device or the image forming device. , These outputs are input. Further, the control circuit 210 of the motor 211 that rotationally drives the fixing roller 1 and the drive circuit 220 of the central heating heater 3a and the end heating heater 3b are also connected to the control device 200, and control signals are output to these. The above-mentioned programs for various controls are stored in a recording unit or the like of the control device 200.

1: Fixing roller 2: Pressurizing roller 3: Heater 3a: Central heater 3b: End heater 4: Thermopile 9: End thermistor 11: In-flight temperature detector 12: In-flight humidity detector 13: External temperature detector 14: External humidity detector 100a: Image forming device case 170a: Fixer case 200: Control device 210: Control circuit 211: Motor 220: Drive circuit T: Thermopile part temperature T0: Fixing roller center actual temperature T1: Thermopile temperature reading Value T10: Minimum temperature T1': Target temperature T2: Thermopile part temperature Ta: Outside atmosphere temperature Tb: Temperature rise detection time a1: Environmental temperature change t0: Start-up start vs: Inside-outside temperature difference y: Rise z: Predetermined Time ΔTc: Temperature rise gradient

Japanese Unexamined Patent Publication No. 2010-72329 Japanese Unexamined Patent Publication No. 2006-145966

Claims (23)

It has a heat source, a fixing member, a pressurizing member, and an infrared temperature detecting means that detects infrared rays generated from the surface of the fixing member or the surface of the pressurizing member and measures the temperature.
After a lapse of a predetermined time within 10 seconds from the start of lighting of the heat source, the relationship between the output of the infrared temperature detecting means and the output of the surface temperature detecting means of another fixing member or pressure member other than the infrared temperature detecting means, or The relationship between the output of the infrared temperature detecting means or the temperature detecting means for detecting the vicinity temperature of the infrared temperature detecting means and the output of the outside air temperature detecting means, or the output of the infrared near temperature detecting means and the output of the outside air temperature detecting means. When any of the relationship between the output of the outside air humidity detecting means and the output of the outside air humidity detecting means satisfies a predetermined relationship, the heat source is continuously lit, or the fixing member and the pressurizing member are driven while the heat source is lit. A fixing device comprising selecting whether to reduce the output of the heat source or stop lighting the heat source. The fixing device according to claim 1.
It has a surface temperature detecting means of another fixing member or a pressurizing member which is not the infrared temperature detecting means.
Starting from the elapse of the predetermined time, the amount of temperature rise of the output temperature of the infrared temperature detecting means during the elapse of the set time set from the starting point to 1 to 5 seconds, and other fixing members other than the infrared temperature detecting means. Or, when the difference between the output temperature of the surface temperature detecting means of the pressurizing member and the amount of temperature rise exceeds the threshold value.
A fixing device characterized in that the output of the heat source is reduced, the lighting of the heat source is stopped, or the fixing member and the pressurizing member are driven while the heat source is lit. The fixing device according to claim 2.
A fixing device characterized in that it is determined whether or not the opening exceeds a threshold value based on whether or not the difference in the amount of temperature rise exceeds the threshold value. The fixing device according to claim 3
A fixing device characterized in that the threshold value is a set value of 40 deg to 50 deg. The fixing device according to claim 2.
A fixing device characterized in that it is determined whether or not the opening exceeds a threshold value based on whether or not the ratio of the amount of temperature rise exceeds the threshold value. The fixing device according to claim 5.
(Amount of temperature rise of the infrared temperature detecting means / Amount of temperature rise of the other temperature detecting means) / (Amount of temperature rise of the infrared temperature detecting means when no droplets are attached / Amount of temperature rise of the other temperature detecting means) ) A fixing device characterized in that it is determined that the threshold value has been exceeded when the set value of ≤0.75 to 0.8 is satisfied. The fixing device according to claim 1.
It has a surface temperature detecting means of another fixing member or a pressing member other than the infrared temperature detecting means for detecting the temperature of the surface of the fixing member or the surface of the pressurizing member.
When the difference between the output temperature of the infrared temperature detecting means and the output temperature of the surface temperature detecting means of another fixing member or pressurizing member other than the infrared temperature detecting means exceeds the threshold value.
A fixing device characterized in that the output of the heat source is reduced, the lighting of the heat source is stopped, or the fixing member and the pressurizing member are driven while the heat source is lit. The fixing device according to claim 7.
A fixing device characterized in that it is determined whether or not the opening exceeds a threshold value based on whether or not the difference in output temperature exceeds the threshold value. The fixing device according to claim 7.
A fixing device for determining whether or not the opening exceeds a threshold value based on whether or not the ratio of the output temperatures exceeds the threshold value. The fixing device according to claim 1.
Temperature A detecting means for detecting temperature A (deg) in the vicinity of the infrared temperature detecting means or the infrared temperature detecting means, humidity B detecting means for detecting the humidity B (%) in the vicinity of the infrared temperature detecting means, and outside the machine. Alternatively, it has a temperature C detecting means for detecting a temperature C (deg) near the outside of the machine.
When the relationship of the set values within CA + 0.3 × B ≧ 27 to 35 is satisfied, the output of the heat source is reduced, the lighting of the heat source is stopped, or the fixing member and the addition while lighting the heat source. A fixing device characterized by driving a pressure member. The fixing device according to any one of claims 1 to 10.
The lighting of the heat source is controlled so that the detection temperature of the infrared temperature detecting means is maintained at 120 ° C. to 180 ° C. during the driving of the fixing member and the pressurizing member while lighting the heat source. A fixing device characterized by the fact that. The fixing device according to claim 11.
A target temperature for controlling the detection temperature of the infrared temperature detecting means to a predetermined value of 120 ° C. to 180 ° C. and a driving time for continuing the driving are set in advance.
A fixing device characterized in that the driving is continued for the driving time under the lighting control at the target temperature. The fixing device according to claim 11 or 12.
After the elapse of the driving time, when the temperature A (deg) in the vicinity of the infrared temperature detecting means or the infrared temperature detecting means is set, and the temperature C (deg) in the vicinity of the outside of the machine is set outside the machine.
A> = C + 20
A fixing device characterized in that the output of the heat source is increased when the above relationship is satisfied. The fixing device according to claim 11 or 12.
A temperature A detecting means for detecting a temperature A (deg) in the vicinity of the infrared temperature detecting means or the infrared temperature detecting means, a humidity B detecting means for detecting a humidity B (%) in the vicinity of the infrared temperature detecting means, and a humidity B detecting means. It has a temperature C detecting means for detecting the temperature C (deg) outside or near the outside of the machine.
A fixing device characterized in that the output of the heat source is increased when the relationship of set values within CA + 0.3 × B <27 to 35 is satisfied. The fixing device according to claim 11 or 12.
It has a temperature A detecting means for detecting a temperature A (deg) near the infrared temperature detecting means or the infrared temperature detecting means, and a temperature C detecting means for detecting a temperature C (deg) outside the machine or near the outside of the machine. ,
A <C + 20
A fixing device characterized in that the output of the heat source is reduced or the lighting is stopped when the above relationship is satisfied. The fixing device according to claim 11 or 12.
A temperature A detecting means for detecting a temperature A (deg) in the vicinity of the infrared temperature detecting means or the infrared temperature detecting means, a humidity B detecting means for detecting a humidity B (%) in the vicinity of the infrared temperature detecting means, and a humidity B detecting means. It has a temperature C detecting means for detecting the temperature C (deg) outside or near the outside of the machine.
A fixing device characterized in that the output of a heat source is reduced or lighting is stopped when the relationship of set values within CA + 0.3 × B> = 27 to 35 is satisfied. The fixing device according to claim 12.
A temperature A detecting means for detecting a temperature A (deg) in the vicinity of the infrared temperature detecting means or the infrared temperature detecting means, a humidity B detecting means for detecting a humidity B (%) in the vicinity of the infrared temperature detecting means, and a humidity B detecting means. It has a temperature C detecting means for detecting the temperature C (deg) outside or near the outside of the machine.
Before the elapse of the driving time, A> = C + 20
Or, when at least one of the set values within CA + 0.3 × B <27 to 35 is satisfied,
A fixing device characterized by increasing the output of the heat source. The fixing device according to any one of claims 13 to 17, wherein the fixing device according to claim 12 or claim 2 is cited.
A fixing device characterized in that the driving time is set to 600 seconds or less. The fixing device according to any one of claims 1 to 17.
The fixing device, wherein the predetermined time is between 3 and 7 seconds. The fixing device according to any one of claims 2 to 6 and 11 to 19.
The fixing device, wherein the predetermined time is 3 to 5 seconds, and the time obtained by adding the predetermined time and the set time is 7 seconds or less. A heat source, a fixing member, a pressurizing member, an infrared temperature detecting means that detects infrared rays generated from the surface of the fixing member and measures the temperature, and a temperature A (deg) in the vicinity of the infrared temperature detecting means or the infrared temperature detecting means. ), Temperature B detecting means for detecting humidity B (%) in the vicinity of the infrared temperature detecting means, and temperature C detection for detecting temperature C (deg) outside or near the outside of the machine. Have a means,
When the relationship of the set values within CA + 0.3 × B> = 27 to 35 is satisfied, the output of the heat source is reduced, the lighting of the heat source is stopped, or the fixing member and the fixing member while lighting the heat source. A fixing device characterized by driving a pressurizing member. The fixing device according to any one of claims 1 to 9 and 11 to 20.
A fixing device characterized in that the surface temperature detecting means of another fixing member or pressure member other than the infrared temperature detecting means is a contact type thermistor. An image forming apparatus having the fixing apparatus according to any one of claims 1 to 21.

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