JP2009075375A - Fixing device for electrophotographic printer - Google Patents

Abstract

An object of the present invention is to stabilize printing quality by detecting abnormalities on the surface of a heating roll such as film abrasion and film peeling, and to determine the exact life of the heating roll, thereby extending the life of the heating roll.
A first surface temperature detected by a first temperature detecting means in a heating roll axial direction by means of temperature measuring means arranged in the axial direction of the surface of the heating roll and capable of detecting surface temperatures at a plurality of locations; Compare the second surface temperature detected by the adjacent second temperature measuring means, and detect a heating roll surface abnormality when a predetermined temperature difference is exceeded, or the first time stored in the storage device By comparing the surface temperature with the surface temperature at the second time at the same point and detecting a heating roll surface abnormality when a predetermined temperature difference is exceeded, the accurate life of the heating roll is determined.
[Selection] Figure 5

Description

  The present invention relates to a fixing device of an electrophotographic printing apparatus.

  A configuration of a fixing device in a conventional electrophotographic printing apparatus will be described with reference to FIG. It has a rotatable heating roll 2 having a heating means 1 inside, and a rotatable pressure roll 3 pressed against the heating roll 2, and a toner image at a pressure contact portion between the heating roll 2 and the pressure roll 3. The recording material 5 holding 4 is nipped and conveyed while applying a heating and pressing action, and the toner image 4 becomes an image 6 fixed on the surface of the recording material.

  In order to obtain a stable fixing strength of the toner image, in order to keep the amount of heat applied to the recording material of the heating roll 2, temperature measuring means 7 on the surface of the heating roll such as a thermopile is provided in the axial direction of the outer peripheral surface of the heating roll 2. The main control unit 8 compares the surface temperature of the heating roll 2 obtained from the temperature measuring unit 7 with a certain temperature (target set temperature) suitable for fusing and fixing the toner image 4, and the heating unit control unit The ON / OFF information of the heating means 1 is sent to 9. The heating means controller 9 drives the heating means 1 according to the ON / OFF information.

  On the other hand, there is known a method of detecting the surface temperature abnormality of the heating roll 2 when the surface temperature of the heating roll 2 cannot be maintained at the target set temperature due to the abnormality of the heating means 1 or the abnormality of the heating means control unit 9. . Conventionally, in this type of temperature abnormality detecting means, the time until the temperature of the heating roll 2 reaches a specific temperature and the time after reaching the specific temperature and below the specific temperature are monitored to detect the abnormality. There is something.

  There has also been proposed a fixing device provided with means for detecting a high temperature abnormality of the heating roll 2.

  Furthermore, as a method for detecting the life of the heating roll 2, the heating roll 2 can be detected by comparing the heating roll life value set in advance based on the experimental prediction with the printing amount (use amount) from when the heating roll 2 is replaced. There is known a method for detecting the replacement time.

JP 2004-191791 A JP 2005-353460 A

  However, the above prior art has the following problems. For example, when damage such as film peeling occurs on a part of the surface of the heating roll, the damaged portion does not have a temperature suitable for melting and fixing the toner image, and printing is performed using the heating roll in this state. In such a case, it leads to an image defect due to fixing failure, but could not be detected as an abnormality.

  Also, in the past, the life was judged by comparing the print amount after the heating roll was replaced with the preset life value of the heating roll, so the difference in the amount of paper to be printed, paper width, print density, etc. There is a problem that the life of the heating roll cannot be accurately grasped because the life time due to film abrasion or film peeling of the heating roll changes due to the difference in temperature setting.

  An object of the present invention is to provide a fixing device of an electrophotographic printing apparatus that can detect an abnormality of the surface due to film abrasion, film peeling, etc. of a heating roll and judge an accurate life of the heating roll.

  In order to achieve the above object, the first means of the present invention includes a rotatable heating roll having a heating means for heating and fixing a toner image transferred to a recording material, and an axial direction of the heating roll. A plurality of temperature detecting means arranged at predetermined intervals and spaced from the outer peripheral surface of the heating roll, and the temperature detecting means detects surface temperatures at a plurality of locations in the axial direction of the outer peripheral surface of the heating roll. In the fixing device of the electrophotographic printing apparatus capable of detecting, the first surface temperature detected by the first temperature detecting means of the temperature detecting means and the second temperature detecting means adjacent to the first temperature detecting means are detected. The second surface temperature is compared, and when the difference between the first surface temperature and the second surface temperature exceeds a predetermined temperature difference, it is determined that the heating roll is abnormal. To do.

  The second means of the present invention includes a rotatable heating roll provided with heating means for heating and fixing the toner image transferred to the recording material, and an axial direction of the heating roll arranged at predetermined intervals. In a fixing device of an electrophotographic printing apparatus having a temperature detecting means arranged with a gap with respect to the outer peripheral surface of the heating roll and a storage device capable of storing the surface temperature detected by the temperature detecting means, the temperature detecting means detects the temperature. The surface temperature of the rotating heating roll is periodically stored in the storage device, and the surface temperature at the second time at the same point as the stored surface temperature at the first time at each point in the axial direction of the heating roll. And when the difference between the surface temperature at the first time and the surface temperature at the second time exceeds a predetermined temperature difference, it is determined that the heating roll is abnormal. .

  By configuring the present invention as described above, the replacement period of the heating roll can be extended by detecting an appropriate life of the heating roll. In addition, stable printing quality can be maintained by detecting abnormalities in the heating roll at an early stage.

  Without adding a new mechanism to the configuration of the conventional fixing device, by comparing the surface temperature in the heating roll axial direction detected by the temperature measuring means, and by comparing the surface temperature in the circumferential direction of the heating roll, Realized the detection of abnormalities.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 is a configuration diagram of a fixing device of an electrophotographic printing apparatus to which the present invention is applied. The temperature measuring means 7 installed with a gap in the axial direction of the heating roll 2 can detect surface temperatures at a plurality of locations in the axial direction of the heating roll 2. Here, the measurement points for detecting the surface temperatures at a plurality of locations are denoted as a to r. The surface temperature detected at each measurement point is sent to the main control unit 8, and the main control unit 8 compares the received surface temperature with the target set temperature, and transmits ON / OFF information to the heating means control unit 9. The heating means controller 9 controls the heating means 1 to be turned on / off.

  FIG. 3 is a diagram illustrating an example of a temperature distribution in the axial direction of the heating roll 2. The horizontal axis represents the measurement points a to r described above, and the vertical axis represents the temperature. In this example, the temperature distribution of the heating roll is a gentle convex shape, and it is determined that there is no abnormality on the surface of the heating roll 2.

FIG. 4 is a diagram illustrating an example of the temperature distribution in the axial direction of the heating roll 2 as in FIG. 3. The horizontal axis represents the measurement points a to r described above, and the vertical axis represents the temperature. In this example, a rapid temperature change can be seen between two points, measurement point l and measurement point m. Here, if the temperature difference between the measurement point l and the measurement point m is ΔT _1−m , and the temperature difference that is determined to be an abnormal surface temperature is ΔT ₁ , ΔT _1−m in this example is a temperature difference larger than ΔT _1. Determines that film abrasion or the like has occurred between the measurement points 1 and m on the surface of the heating roll.

That is, in the configuration shown in FIG. 2, the main control unit 8 performs the following determination in order to detect a temperature abnormality on the surface of the heating roll. Assuming that the surface temperatures of adjacent measurement points (for example, a and b) are X and Y, respectively, if the temperature difference between X and Y exceeds a temperature difference ΔT1 sufficient to determine an abnormality, a temperature abnormality is To detect. Here, a temperature ΔT1 sufficient for detecting an abnormality on the surface of the heating roll is set in advance based on experimental prediction. From the above results, the condition for detecting an abnormality in the main control unit 8 based on the surface temperature received from the temperature measuring means 7 can be expressed by the following equation.
| X-Y |> ΔT1
When the relationship of this expression is true, the main control unit 8 detects an abnormality, and when the relationship is false, it determines that there is no abnormality on the surface of the heating roll.

  FIG. 5 is a diagram illustrating an example of a processing flow when the main control unit 8 actually detects an abnormality on the surface of the heating roll in the configuration illustrated in FIG. 2. In step 5a, the surface temperature obtained from the measurement point a is substituted for X in equation (1). Next, in step 5b, the surface temperature obtained from the adjacent measurement points is substituted into Y in equation (1). For example, when the surface temperature of X is a value from the measurement point a, Y substitutes the surface temperature from the measurement point b. In step 5c, it is determined whether or not the condition of Equation 1 is true between the X measurement point and the Y measurement point. If the result is true, the surface temperature abnormality is detected in step 5d, and the process flow is exited. If the result is false, the surface temperature assigned to Y in step 5e is assigned to X. In step 5f, if the surface temperature substituted for X is not the final measurement point r, the process returns to step 5b, Y is updated, and the temperature abnormality detection process is continued. If the surface temperature assigned to X is the final measurement point r, the process flow is exited.

  Here, the surface temperatures to be compared are adjacent measurement points, but this is not limited as long as the points to be compared are determined in consideration of the interval between the measurement points.

  FIG. 6 is a configuration diagram of the fixing device of the electrophotographic printing apparatus for explaining another abnormality detecting means according to the present invention. The rotatable heating roll 2 rotates at a constant speed in the circumferential direction, is arranged at a predetermined interval in the axial direction of the heating roll 2, and the temperature detecting means 7 installed with a gap with respect to the outer circumferential surface of the heating roll includes: The surface temperature at a plurality of locations in the axial direction of the heating roll 2 can be detected at an arbitrary timing. Here, the measurement points for detecting the surface temperatures at a plurality of locations are denoted as a to r. The surface temperature detected at each measurement point is sent to the main control unit 8, and the main control unit 8 compares the received surface temperature with the target set temperature, and transmits ON / OFF information to the heating means control unit 9. The heating means controller 9 controls the heating means 1 to be turned on / off. The main control unit 8 stores the surface temperature of each measurement point received from the temperature measuring means 7 in the storage device 10 every time it is received, and stores the stored surface temperature at the first time and then the temperature detection. The surface temperature at the second time at the same point detected by the means 7 is compared. That is, the temperature difference in the circumferential direction at the same measurement point is detected.

  FIG. 7 is a diagram illustrating an example of a temperature difference in the circumferential direction of the heating roll 2 at each measurement point at an arbitrary timing. The horizontal axis represents the measurement points a to r described above, and the vertical axis represents the temperature difference in the circumferential direction of the heating roll. In this example, since there is no protruding temperature difference in the circumferential direction of the heating roll 2, it is determined that there is no abnormality.

  FIG. 8 is a diagram illustrating an example of a temperature difference in the circumferential direction of the heating roll 2 at each measurement point at an arbitrary timing, as in FIG. The horizontal axis represents the measurement points a to r described above, and the vertical axis represents the temperature difference in the circumferential direction of the heating roll. In this example, a large temperature difference in the circumferential direction can be seen at the measurement points k, l, and m. Here, if the temperature difference that is determined to be an abnormality in the surface temperature is ΔT2, in this example, a temperature change larger than ΔT2 can be seen in the circumferential direction between the measurement point k and the measurement point l. It can be determined that the temperature change is observed when film peeling or the like occurs on the surface.

以上の傾向より図６に示す構成において、メイン制御部８は加熱ロール表面の温度異常を検出する為に、以下の判断を実施する。検温手段７より受信した測定点ａにおける表面温度をＱ１とし、記憶装置１０に格納されている前回の測定点ａにおける表面温度をＰ１とすると、Ｑ１とＰ１の温度差が、異常と判断するのに十分な温度差ΔＴ２を越えていた場合、温度異常を検出する。ここで、加熱ロール表面の異常を検出するのに十分な温度差ΔＴ２は、予め実験予測に基いて設定しておく。以上の結果より、検温手段７より受信した測定点ａの記憶装置１０に格納された表面温度と次に読み込んだ表面温度を基にメイン制御部８で異常を検出する条件は、次の式で表すことが出来る。
｜Ｐ１−Ｑ１｜＞ΔＴ２
この式の関係が真の場合、メイン制御部８は、異常を検出し、偽の場合は、加熱ロール表面の異常は無しと判断する。同様に検温手段７より受信した測定点ｂにおける加熱ロール周方向の異常を検出する条件は、次の式で表すことが出来る。
｜Ｐ２−Ｑ２｜＞ΔＴ２
この式においてＱ２は、検温手段７より受信した測定点ｂにおける表面温度を表し、Ｐ２は、記憶装置１０に格納されている前回の測定点ｂにおける表面温度を表す。

From the above tendency, in the configuration shown in FIG. 6, the main control unit 8 performs the following determination in order to detect a temperature abnormality on the surface of the heating roll. If the surface temperature at the measurement point a received from the temperature measuring means 7 is Q1, and the surface temperature at the previous measurement point a stored in the storage device 10 is P1, the temperature difference between Q1 and P1 is determined to be abnormal. If a sufficient temperature difference ΔT2 is exceeded, a temperature abnormality is detected. Here, a temperature difference ΔT2 sufficient to detect an abnormality on the surface of the heating roll is set in advance based on experimental prediction. From the above results, the condition for detecting an abnormality in the main control unit 8 based on the surface temperature stored in the storage device 10 at the measurement point a received from the temperature measuring means 7 and the surface temperature read next is as follows: Can be expressed.
| P1-Q1 |> ΔT2
When the relationship of this expression is true, the main control unit 8 detects an abnormality, and when the relationship is false, it determines that there is no abnormality on the surface of the heating roll. Similarly, the condition for detecting an abnormality in the circumferential direction of the heating roll at the measurement point b received from the temperature measuring means 7 can be expressed by the following equation.
| P2-Q2 |> ΔT2
In this equation, Q2 represents the surface temperature at the measurement point b received from the temperature measuring means 7, and P2 represents the surface temperature at the previous measurement point b stored in the storage device 10.

  Hereinafter, similarly, the conditions for detecting abnormalities in the circumferential direction of the heating roll at each measurement point can be expressed by the following equations.

| Px−Qx |> ΔT2
In this equation, P represents the previous surface temperature stored in the storage device 10, and Q represents the surface temperature received from the temperature measuring means 7 this time. A subscript x represents each measurement point.

  In the present invention, ΔT2 is determined as a value that can sufficiently detect a temperature abnormality, but the abnormality detection temperature may be determined for each measurement point according to the surface temperature distribution tendency of the heating roll 2.

  FIG. 9 is a diagram illustrating an example of a processing flow when the main control unit 8 actually detects an abnormality on the surface of the heating roll in the configuration illustrated in FIG. 6. In step 9a, the surface temperature obtained from the measurement point a is substituted for Qx in Equation 2. Next, in step 9b, the surface temperature at the same measurement point as Qx is substituted into Px from the surface temperature detected by the previous temperature detecting means 7 stored in the storage device 10. When Qx is the surface temperature from the measurement point a, Px substitutes the surface temperature detected by the previous measurement point a. In step 9c, the authenticity of the condition of Formula 2 is determined based on the previous measurement interval and the current measurement interval in the circumferential direction. If the result is true, the surface temperature abnormality is detected in step 9d, and the process flow is exited. If the result is false, the surface temperature of the adjacent measurement point is substituted for Qx in step 9e. In step 9f, if the surface temperature substituted for Px is not the final measurement point r, the process returns to step 5b to update Px and continue the temperature abnormality detection process. If the surface temperature assigned to Px is the final measurement point r, the surface temperature of the temperature measuring means 7 is stored in the storage device 10 in step 9g and the processing flow is exited, assuming that no temperature abnormality has been detected in the circumferential surface temperature. .

  In this embodiment, only the comparison between the previous surface temperature and the current surface temperature stored in the storage device 10 is made. However, this is not limited if the point to be compared is determined in consideration of the surface temperature reading interval in the circumferential direction. .

  With the above-described configuration, it is possible to detect an abnormality of the heating roll 2, and an appropriate life of the heating roll 2 can be detected.

  The present invention can be applied to anomaly detection of the surface temperature of a heating body having a heat source capable of rotating motion.

It is a block diagram of a fixing device in a conventional electrophotographic printing apparatus. 1 is a configuration diagram of a fixing device of an electrophotographic printing apparatus to which the present invention is applied. It is the figure which showed an example of the temperature distribution in the axial direction of a heating roll. It is the figure which showed an example when abnormality is seen in the temperature distribution in the axial direction of a heating roll. It is the flowchart which showed the processing content which detects the abnormality. 1 is a configuration diagram of a fixing device of an electrophotographic printing apparatus to which the present invention is applied. It is the figure which showed an example of the temperature difference when each measurement point of a heating roll and the data of a memory | storage device were compared. It is the figure which showed an example of the temperature difference when abnormality is seen in the temperature difference when each measurement point of a heating roll and the data of a memory | storage device are compared. It is the flowchart which showed the processing content which detects the abnormality.

Explanation of symbols

  1 is a heating unit, 2 is a heating roll, 3 is a pressure roll, 4 is a toner image, 5 is a recording material, 6 is an image after fixing, 8 is a main control unit, 9 is a heating unit control unit, and 10 is a storage device. It is.

Claims (2)

A rotatable heating roll having heating means for heating and fixing the toner image transferred to the recording material, and a gap between the heating roll and the outer peripheral surface of the heating roll arranged at predetermined intervals in the axial direction of the heating roll. In the fixing device of the electrophotographic printing apparatus, which has a plurality of temperature measuring means disposed and can detect the surface temperature at a plurality of locations in the axial direction of the outer peripheral surface of the heating roll,
The first surface temperature detected by the first temperature detection means of the temperature detection means is compared with the second surface temperature detected by the second temperature detection means adjacent to the first temperature detection means, A fixing device for an electrophotographic printing apparatus, wherein when a difference between one surface temperature and the second surface temperature exceeds a predetermined temperature difference, it is determined that the heating roll is abnormal. A rotatable heating roll having heating means for heating and fixing the toner image transferred to the recording material, and a gap between the heating roll and the outer peripheral surface of the heating roll arranged at predetermined intervals in the axial direction of the heating roll. In a fixing device of an electrophotographic printing apparatus having a temperature detecting means placed and a storage device capable of storing a surface temperature detected by the temperature detecting means,
The surface temperature of the rotating heating roll detected by the temperature measuring means is periodically stored in the storage device, and the same point as the stored surface temperature at the first time at each point in the axial direction of the heating roll. And comparing the surface temperature at the second time in the case where the difference between the surface temperature at the first time and the surface temperature at the second time exceeds a predetermined temperature difference, it is determined that the heating roll is abnormal. A fixing device for an electrophotographic printing apparatus.

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