JP2001242740A - Fixing device and image forming device equipped with the fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the fixing device in which the protection of an excessive temperature up of a heating body or defective fixing due to disconnection or loose connection or the like of a temperature detection body or the heating body can be realized, and the protection of the delay in warmup time of the heating body due to the fluctuation of an operating environment temperature of the device or working power supply voltage can be realized at a low cost, and to provide an image forming device equipped with the fixing device. SOLUTION: A judging means 118 for prohibiting heating acquires real time information, and electric power supply from a power source to heaters 113, 114 are prohibited for a prescribed period when the elapsed time from the heating stop of the heaters 113, 114 is prescribed time length or less on the basis of the real time information and heat time information stored in a storage means 119 and abnormalities in detection are stored in the storage means 119.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus provided with the fixing device.

[0002]

2. Description of the Related Art Conventionally, in a fixing device provided in an image forming apparatus such as a printer, a fixing roller serving as a fixing member and a pressing roller serving as a pressing member which are pressed against each other and rotated, and the fixing roller and the pressing roller are provided. There is known a heat roller type fixing device having a heater as a heating element for heating at least one of the above.

In such a fixing device, a transfer sheet, which is a recording medium carrying a toner image as an unfixed image, is passed between the fixing roller and the pressure roller and heated and pressed to form the toner image. The sheet is fused and fixed on the transfer paper.

In such a fixing device, the temperature of the surface of the fixing roller is generally detected by a temperature sensor such as a thermistor disposed in contact with or close to the surface of the fixing roller. The detected temperature information is input to a controller such as a microcomputer via a temperature detection circuit, and is compared with a preset control target value of the fixing roller surface temperature. When the surface temperature of the fixing roller detected by the temperature sensor is lower than the lower limit of the control target temperature, the heater is turned on, and when the surface temperature exceeds the upper limit of the control temperature target, the heater is turned off. The power supplied to the heater is controlled, and the surface temperature of the fixing roller is maintained within a predetermined temperature range.

[0005]

However, in such a fixing device, in order to check the temperature rise by heating the heater after turning on the power, the heating device must be heated to some extent before it enters the detection sensitivity range of the temperature sensor. Therefore, early detection is difficult. For example, if the connection of the temperature sensor is broken during heating of the heater, if the power supply for supplying power to the heater is cut off and turned on again, the temperature of the heater rises abnormally. There was a fear.

One of the causes is that, in the temperature sensor used in such a fixing device, the detection sensitivity is remarkably lowered in a temperature range around room temperature (room temperature), and the control resolution is secured. Therefore, it is difficult to detect the temperature in both the fixing device temperature control range and the normal temperature range. This can be avoided by separately providing a temperature sensor having a characteristic different from that of the temperature sensor for the fixing device temperature control region (having a sensitivity near normal temperature), but requires an additional circuit and the like.

In such a fixing device, the same abnormalities as described above may occur due to a defect in the thermistor element itself, a defect in the heater itself as a heat source, or a contact failure. There is a possibility that an abnormality that the surface temperature does not rise to a predetermined temperature and the fixing cannot be performed may occur.

Further, in such a fixing device, when the operating environment temperature and the operating power supply voltage value are lower than the guaranteed operating range, the temperature of the heater surface may fluctuate, and the warm-up time may be delayed. is there.

Accordingly, the present invention can prevent inexpensive heating of the heating element and defective fixing due to disconnection and poor contact of the temperature detecting element and the heating element, and furthermore, can prevent the temperature of the operating environment of the apparatus. It is an object of the present invention to provide a fixing device capable of preventing a warm-up time of a heating element from being delayed due to a change in a used power supply voltage, and an image forming apparatus including the fixing device.

[0010]

According to the present application, the object is to provide a fixing member and a pressing member which rotate in pressure contact with each other, and at least the fixing member and the pressing member which receive heat from a power source to generate heat and receive heat. A heating element for heating one of them, a temperature detection element for detecting a surface temperature of at least one of the fixing element and the pressure element, and an electric power from a power supply to the heating element so that the detected temperature of the temperature detection element becomes a target temperature. And a control unit for controlling the supply, wherein the recording medium holding the unfixed image is nipped and conveyed by the fixing body and the pressurizing body, and pressurized and heated to fix the unfixed image on the recording medium. In the fixing device,
Abnormality detecting means for detecting an abnormality of at least one of the heating element and the temperature detecting element, heating time information means for acquiring heating time information of heating start and heating stop of the heating element, and detection abnormality and time information means of the abnormality detecting means Storage means capable of storing the obtained heating time information, and real time information being obtained, and based on the real time information and the heating time information, the elapsed time from the heating stop is equal to or less than a predetermined time length and the detection abnormality is detected. The present invention is achieved by the first invention including a prohibition unit for prohibiting the power supply from the power supply to the heating element for a predetermined period when is stored in the storage unit.

Further, according to the present application, the above object is achieved in the first invention in that, when the power from the power supply to the heating element is cut off and then turned on again, the abnormality detecting means is connected to the cutoff of the electric power. The temperature corresponding to the temperature drop of the heating element based on the time length from the detection temperature of the temperature detection element when the power is cut off when the time length of the heating stop state until re-input is equal to or less than the predetermined time length. The present invention is also achieved by the second invention in which an abnormality is set to be detected when the temperature detected by the temperature detector is lower.

Further, according to the present application, the above object is achieved in the first invention or the second invention, wherein the control means controls the power supply from the power supply to the heating element so that the temperature detected by the temperature detection element becomes the target temperature. The present invention is also achieved by the third invention in which the power supply cycle per unit time can be changed.

Further, according to the present application, the above object is to provide an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, which is provided with a fixing device of the first invention. The invention is also achieved by the invention of (1).

Further, according to the present application, the above object is attained in the fourth invention in that, when the power from the power supply to the heating element is cut off and then turned on again, the abnormality detecting means is connected to the cutoff of the electric power. The temperature corresponding to the temperature drop of the heating element based on the time length from the detection temperature of the temperature detection element when the power is cut off when the time length of the heating stop state until re-input is equal to or less than the predetermined time length. The present invention is also achieved by the fifth invention in which an abnormality is set to be detected when the temperature detected by the temperature detector is lower.

Further, according to the present application, the above object is achieved in the fourth or fifth aspect of the present invention in that the control means controls the power supply from the power supply to the heating element so that the temperature detected by the temperature detecting element becomes the target temperature. The present invention is also achieved by the sixth invention in which the power supply cycle per unit time can be changed.

That is, in the first invention according to the present application, the prohibiting means sets the elapsed time from the stop of the heating of the heating element to a predetermined time length or less and stores the detected abnormality of the abnormality detecting means in the storage means. If it is stored, the power supply from the power supply to the heating element is prohibited for a predetermined period.

Further, in the second invention according to the present application, the abnormality detecting means determines that the time length of the heating stop state from the interruption of power supply to the heating element from the power supply to the re-input is not more than the predetermined time length. When the detected temperature of the temperature detector is lower than the temperature corresponding to the temperature drop of the heater based on the time length from the detected temperature of the temperature detector when the power is cut off, the abnormality is detected and prohibited. Means for prohibiting power supply from the power supply to the heating element for a predetermined period when the elapsed time from the stop of heating of the heating element is equal to or less than a predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means. .

Further, in the third invention according to the present application, the control means sets an energizing cycle per unit time of electric power from the power supply to the heating element so that the temperature detected by the temperature detecting element becomes the target temperature. The power supply from the power supply to the heating element is performed when the time elapsed from the stop of the heating of the heating element is equal to or less than the predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means. For a predetermined period.

In the fourth invention according to the present application, the prohibiting means is configured so that the elapsed time from the stop of the heating of the heating element is equal to or less than a predetermined time length, and the abnormality detected by the abnormality detecting means is stored in the storage means. If it is stored, the power supply from the power supply to the heating element is prohibited for a predetermined period.

Further, in the fifth invention according to the present application, the abnormality detecting means determines that the time length of the heating stop state from the interruption of power supply to the heating element from the power supply to the re-input is not more than the predetermined time length. When the detected temperature of the temperature detector is lower than the temperature corresponding to the temperature drop of the heater based on the time length from the detected temperature of the temperature detector when the power is cut off, the abnormality is detected and prohibited. Means for prohibiting power supply from the power supply to the heating element for a predetermined period when the elapsed time from the stop of heating of the heating element is equal to or less than a predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means. .

In the sixth invention according to the present application, the control means sets an energizing cycle per unit time of power from the power supply to the heating element so that the temperature detected by the temperature detecting element becomes the target temperature. The power supply from the power supply to the heating element is performed when the time elapsed from the stop of the heating of the heating element is equal to or less than the predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means. For a predetermined period.

[0022]

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

(First Embodiment) First, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic cross-sectional view showing a schematic configuration of an electrophotographic laser beam printer 1 (hereinafter abbreviated as printer 1) as an example preferably showing the image forming apparatus of the present embodiment.

The printer 1 forms an image on a sheet-shaped recording medium P in accordance with image information provided from an image information providing device (not shown) such as a host computer provided outside the main body of the printer 1. This is an image forming apparatus in which a series of image forming processes of recording is performed according to a known electrophotographic method.

As shown in FIG. 1, the printer 1 includes a photosensitive member 2 serving as a drum-shaped rotatable latent image carrier, and a primary charging roller 8 for charging the outer peripheral surface of the photosensitive member 2 to a specified potential distribution.
A developing device 3; and a laser scanner unit 5 (hereinafter, referred to as a laser scanner unit 5) for forming an electrostatic latent image corresponding to the image information on the outer peripheral surface of the photoreceptor 2 by an exposure process corresponding to the image information from the image information providing device. , A scanner 5), a roll-shaped rotatable transfer member 6 for performing a transfer process on the recording medium P, and a fixing process by heating and pressing the transferred recording medium P. And a fixing device 7.

In this image forming apparatus, first, the photosensitive member 2 starts rotating at a specified peripheral speed in the direction of the arrow shown in FIG. 1, and contacts the charging roller 11 to which a specified bias is applied. The outer peripheral surface of the photoreceptor 2 is charged to a specified potential distribution by sliding contact with the body 2.

Next, the charged portion of the outer peripheral surface of the photoreceptor 2 is scanned and exposed by the scanner 5 according to the image information from the image information providing device, so that an electrostatic latent image corresponding to the image information is obtained. Is formed in the above-described region, the developer of the developing device 3 visualizes the electrostatic latent image into a visible image.

On the other hand, the photosensitive member 2 and the transfer member 6 are rotatable from a cassette 11 which can accommodate a predetermined number of recording media P and is detachably supported by the main body of the printer 1 by a rotatable paper feed roller 12 or the like. It is conveyed to a space formed therebetween at a predetermined timing or the like.

The recording medium P conveyed between the photosensitive member 2 and the transfer member 6 has the transferred image transferred by the transfer member 6.

The transfer-processed recording medium P is subjected to a fixing process by a fixing device 7, and then discharged outside the apparatus by a discharge roller 13 rotatably supported by the main body of the printer 1, and is discharged. By stacking on the tray 14 attached to one side of the main body, a series of image forming processes is completed.

Next, the fixing device 7 will be described with reference to FIG.

FIG. 2 is a block diagram showing the configuration of the fixing device 7 and its control system.

The fixing device 7 includes fixing rollers 115 and 120 serving as a fixing member and a pressing member that rotate in pressure contact with each other, and heaters 113 and 114 serving as heating members that receive heat from a power source and generate heat to heat the fixing rollers 115 and 120. And fixing roller 1
Temperature sensors 116 and 117, which are the temperature detectors for detecting the surface temperatures of the temperature sensors 15 and 120, and the heaters 113 and 117 from the power supply so that the temperature detected by the temperature sensors 116 and 117 becomes the target temperature.
Control means 121 for controlling power supply to the unfixed image 114. The recording medium is fixed on the recording medium.

The fixing device 7 includes a heating prohibition judging means 118 as an abnormality detecting means and a prohibiting means, a timer 105 as a heating time information means, and a storage means 119.

Here, the heaters 113 and 11 of the fixing device 7 are used.
4 or the detection of abnormality of the temperature sensors 116 and 117 will be described.

As shown in FIG. 2, in the control block 101 relating to the control of the fixing device 7 of the printer 1, first,
The heating prohibition determining means 118 in the microcomputer 102
Real-time information is obtained through communication with the third party. Next, the heating prohibition judging means 118 reads out the heating time information 104 for starting and stopping the heating of the heaters 113 and 114 from the storage means 119 composed of an EEPROM or the like.

The real time information and the heating time information 10
4, it is determined whether or not the heaters 113 and 114 have been in the heating stop state for a predetermined time or more, and the heaters 113 and 114 are determined.
If the heating stop state of No. 14 is equal to or less than the predetermined time length, it is confirmed whether the temperature is appropriate for the heating stop time length. That is, the temperature sensors 116 and 117 at this time
If the detected temperature is within the operation guarantee, it is regarded as normal and the control returns to the normal control.

However, the predetermined time length has not elapsed since the heating of the heaters 113 and 114 was stopped, and the
14. When an error log indicating that the temperature sensors 116 and 117 are abnormal remains in the storage unit 119, and when the detected values of the temperature sensors 116 and 117 are low, a warning message is displayed and a standby for a predetermined time is performed. And then the heater 11
3,114 is reheated. During this standby time, the heaters 113 and 114 are energized from normal temperature and the outputs of the temperature sensors 116 and 117
It is necessary to expect a decrease in the temperature of the fixing rollers 115 and 120 to a degree that can be confirmed in the above.

If the fixing roller pair is kept in a pressurized state during heating by the heater, the temperature rise of the contact portion becomes large. A configuration in which pressure is not applied may be adopted.

It is checked whether or not the temperature detection values of the temperature sensors 116 and 117 have reached a predetermined temperature at a predetermined time set by the timer 105 from the start of heating of the heaters 113 and 114. If the temperature has not reached the predetermined temperature, it is determined that the temperature is abnormal. The cause of the abnormality at this time may be that the heaters 113 and 114 are disconnected or the temperature sensor is separated from the fixing roller.

If it is determined that there is an abnormality, the heaters 113, 11
The heating of No. 4 is stopped, and an abnormality is transmitted to the host 103 or displayed on a display panel (not shown). Thereby, the heaters 113 and 114 and the temperature sensors 116 and 117
Is promptly notified to the operator that is abnormal.

Here, if the printer 1 is connected to a network or a telephone line, a service call can be made online. As a result, prompt measures such as replacement of a defective thermistor element can be made.

Until the abnormality is eliminated and the stoppage of the heaters 113 and 114 is canceled by the cancellation means, the fact that the storage means 119 is in an abnormal state is stored and held, thereby preventing malfunction of the machine. It is also possible.

Here, the fixing roller 115,
120 is heated by heaters 113 and 114, respectively. If these are controlled to the same temperature,
Temperature sensors 116 for detecting these roller surface temperatures,
If the temperature difference of 117 does not fall within the predetermined range, it can be determined that the temperature is abnormal.

When the power is turned off and then turned on again, the detected values of the temperature sensors 116 and 117 and the storage means 11
By changing the abnormality detection time setting based on the stored information 9 and the real time information, early detection becomes possible.

The detected temperature values of the temperature sensors 116 and 117 are subjected to A / D conversion by the A / D converter 107 and are taken into the control means 121 in the microcomputer 102.

The A / D converted temperature detection value is LP
After the noise is removed by the F operation unit 108, the comparator 109
Is compared with the target set temperature 106.

The judgment output means 110 judges whether or not to heat the heaters 113 and 114 based on the comparison result of the comparator 109, and finally outputs the result from the microcomputer 102.

On the other hand, the excessive temperature rise prevention circuit 111 detects the excessive temperature rise of the heaters 113 and 114 without the intervention of the microcomputer 102, and stops the heating of the heaters 113 and 114.

The judging circuit 112 determines whether or not to finally supply electric power from the power source to the heaters 113 and 114 based on the judgment result of the heating judging means 110 and the detection result of the overheating of the overheating preventing circuit 111. Make a judgment.

Here, the surface temperature of the fixing rollers 115 and 120 detected by the temperature sensors 116 and 117 is such that the surface temperature of the fixing rollers 115 and 120 cannot be a normal temperature (for example, the temperature is lower than the environmental temperature of the apparatus). Temperature value, etc.), and when it is low, it is determined to be abnormal.

When it is determined that there is an abnormality, the heating inhibition determining means 1
The heating of the heaters 113 and 114 is stopped by 18 and abnormal processing is performed. The cause of this abnormality is that the heater 11
It is conceivable that 3,114 is disconnected.

Further, even if the temperature once exceeds a predetermined temperature, the temperature sensors 1
Since it is possible that the temperature detected by 16, 117 decreases, it is also effective to set the lower limit temperature after the temperature has risen to the predetermined temperature, and to judge that the temperature is lower than this lower limit. In addition, in the event of an abnormality, the display means notifies the operator,
A configuration is also conceivable in which the abnormal state is stored and retained by the retaining unit, and the heating of the heaters 113 and 114 is stopped until the processing is performed by the predetermined releasing unit.

FIG. 3 shows a flowchart of the control operation in the microcomputer 102.

(Step 401) When the power is turned on, the host 1
03, real-time information is obtained.

(Step 402) Heating prohibition judging means 11
8 reads the heating time information from the storage means 119.

(Step 403) Heating prohibition judging means 11
8 determines from the real time information and the heating time information whether or not the heaters 113 and 114 have been in the heating stop state for a predetermined time or more, and if so, proceeds to step 406;

(Step 404) Temperature sensors 116, 1
It is checked whether or not the detected value of 17 is a temperature corresponding to that obtained from the heating time information, and if so, the process proceeds to step 405; otherwise, the process proceeds to step 405.

(Step 405) An error message based on the error log and the heating time information stored in the storage means 119 is displayed on a panel (not shown), and the host 103
Send status. In this state, the process waits until the error is cleared or, if it can be recovered, waits for a predetermined time and proceeds to step 406.

(Step 406) Temperature sensors 116, 1
The detected value 17 is A / D converted by the A / D converter 107 and is taken into the microcomputer 102.

(Step 407) LPF is applied to the detection values of the temperature sensors 116 and 117 taken in the microcomputer 102.
The operation unit 108 performs low-pass filtering for removing noise.

(Step 408) Temperature sensors 116, 1
It is determined whether or not the temperature difference between the temperature sensors 17 and 17 falls within a predetermined range, and whether or not the temperature differences between the temperature sensors 116 and 117 is within a predetermined value. If so, proceed to 410.

(Step 409) Error processing (display on panel, status transmission to host 103) is performed.

(Step 410) The comparator 109 determines whether or not the detected temperatures of the temperature sensors 116 and 117 have reached the target set temperature. If not, the process proceeds to Step 411, and if it has, the process proceeds to Step 412. .

(Step 411) The heater is turned on and the process returns to step 406.

(Step 412) The heater is turned off and the process returns to step 406.

Therefore, according to the present embodiment, the temperature sensors 116, 1 for detecting the surface temperatures of the fixing rollers 115, 120 are provided.
17 or a malfunction due to a poor mounting of the temperature sensors 116 and 117, for example, the fixing roller 11
The temperature of the 5,120 surface is prevented from rising, and the curling and jamming of the paper associated with the temperature are prevented, and the effect of preventing the kidnapping of the device is obtained. In addition, an effect can be obtained in preventing a fixing failure that occurs because the temperature does not reach the predetermined temperature due to the failure of the heaters 113 and 114 and the contact failure.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to the drawings. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, in addition to the fixing device control similar to that of the first embodiment, the control method as shown in FIG. An unnecessary temperature fluctuation is suppressed by calculating a balance with the energization ratio of the heater per unit and performing heating by the energization ratio.

When the temperature exceeds a predetermined temperature from the start of heating when the heaters 113 and 114 are turned on, preset heating control shown in FIG. 4A is performed. This is set, for example, to an energization ratio that maintains the surface temperature of the fixing device at 160 ° C. when the environmental temperature is 25 ° C. and the power supply voltage is 100 V. Then, the balanced temperature is detected, and the energization ratio is corrected.

FIG. 5 shows a flowchart of the control operation in the microcomputer 102.

(Step 501) When the power is turned on, the host 1
03, real-time information is obtained.

(Step 502) Heating prohibition judging means 11
8 reads the heating time information from the storage means 119.

(Step 503) Heating prohibition judging means 11
8 determines from the real time information and the heating time information whether or not the heaters 113 and 114 have been in the heating stop state for a predetermined time or more, and if so, proceeds to step 406;

(Step 504) Temperature sensors 116, 1
It is checked whether or not the detected value of 17 is a temperature corresponding to that obtained from the heating time information, and if so, the process proceeds to step 405; otherwise, the process proceeds to step 405.

(Step 505) An error message based on the error log and heating time information stored in the storage means 119 is displayed on a panel (not shown), and the host 103
Send status. In this state, the process waits until the error is cleared or, if it can be recovered, waits for a predetermined time and proceeds to step 406.

(Step 506) Temperature sensors 116, 1
The detected value 17 is A / D converted by the A / D converter 107 and is taken into the microcomputer 102.

(Step 507) LPF is applied to the detection values of the temperature sensors 116 and 117 taken in the microcomputer 102.
The operation unit 108 performs low-pass filtering for removing noise.

(Step 508) Temperature sensors 116 and 1
It is determined whether or not the temperature difference between the temperature sensors 17 and 17 falls within a predetermined range, and whether or not the temperature differences between the temperature sensors 116 and 117 is within a predetermined value. If so, proceed to 410.

(Step 509) Error processing (display on panel, status transmission to host 103) is performed.

(Step 510) Temperature sensors 116, 1
It is determined whether the detected temperature is equal to or higher than the heater heating control switching set temperature. If the detected temperature is equal to or higher than the heater heating control switching set temperature, the process proceeds to step 512;

(Step 511) Turn on the heater,
Return to step 406.

(Step 512) Temperature sensors 116, 1
It is determined whether the detected temperature is equal to or lower than the target temperature in step S17. If so, the process proceeds to step 413; otherwise, the process returns to step 406.

(Step 513) The heater 11 shown in FIG.
3,114 heating control is performed.

FIG. 4 shows the heating control of the heaters 113 and 114 in step 513 in the flowchart of FIG. The default state in FIG. 4A is a state in which the heater 113, which is stored in the storage means 119 such as an EEPROM or the like, is preset at the time of shipment or based on a heating ratio balanced with the heat radiation from the fixing device 7 measured at the time of previous control. 14 shows an on / off state of the switch 114.

This cycle needs to be a cycle that does not appear in the temperature change of the heater surface (a variation that does not cause a problem in the process), and that the responsiveness of the heater and the influence of flicker must be considered. . Heater 11
By providing a fixed interval between the timings at which the 3,114 switches are turned on, power supply fluctuations affected by this are reduced.

Here, the heaters 113 and 114 are normally
Since the power is supplied directly from the power supply line, it is affected by the power supply voltage fluctuation due to the region, environment, and the like. In addition, it is affected by variations in solids and environmental temperature, resulting in an effect such as a slow warm-up time. To mitigate these effects, monitor the power supply voltage and ambient temperature,
It can be processed, but requires additional components.

Therefore, in the present embodiment, during the control, for example, the detection values of the temperature sensors 116 and 117 several minutes after the change to the energization ratio per predetermined time and the target temperature (the energization ratio) By changing the energization note based on the difference from the default temperature corresponding to (i), appropriate heating control can always be realized (FIG. 4B,
(C)). In addition, regarding the control method of the heat supply, see FIG.
It is also possible to add an ON period to each energizing cycle as described above.

Further, at the time of paper passing, the amount of heat corresponding to the loss is set based on information such as the paper type, width, and length, and is added to the power supply cycle to suppress temperature fluctuation during paper passing. Becomes possible.

That is, the control means 121 controls the heater 113,
The energization period per predetermined unit time to the power supply 114 can be changed, so that the energization cycle is changed based on the stable detection values of the temperature sensors 116 and 117 and the target temperature, so that the use environment temperature and the power supply By performing optimal heating control in accordance with the voltage, a change in the temperature of the surface of the fixing roller during temperature control is suppressed.

Therefore, according to the present embodiment, the temperature sensors 116, 1 for detecting the surface temperatures of the fixing rollers 115, 120 are used.
17 or a malfunction due to a poor mounting of the temperature sensors 116 and 117, for example, the fixing roller 11
The temperature of the 5,120 surface is prevented from rising, and the curling and jamming of the paper associated with the temperature are prevented, and the effect of preventing the kidnapping of the device is obtained. In addition, an effect can be obtained in preventing a fixing failure that occurs because the temperature does not reach the predetermined temperature due to the failure of the heaters 113 and 114 and the contact failure.

Further, according to the present embodiment, the energizing cycle per unit time of the heaters 113 and 114 is changed according to the stable detection values of the temperature sensors 116 and 117 and the target temperature, so that the operating environment temperature, By performing the optimal heating control according to the used power supply voltage, the effect of suppressing the temperature fluctuation on the surfaces of the fixing rollers 115 and 120 during the temperature control can be obtained.

[0094]

As described above, according to the first aspect of the present invention, the prohibiting means determines that the elapsed time from the stop of heating of the heating element is less than or equal to the predetermined time length and that the abnormality detecting means detects the abnormality. When the abnormality is stored in the storage unit, the power supply from the power supply to the heating element is prohibited for a predetermined period, so that the temperature of the heating element is prevented from being excessively heated or the fixing failure due to disconnection or poor contact of the heating element. Can be achieved.

According to the second invention of the present application,
When the time length of the heating stop state from the interruption of the power to the heating element from the power supply to the re-input is less than or equal to the predetermined time length, the abnormality detection means detects the temperature from the temperature detected by the temperature detection element at the time of the interruption of the electric power. When the detected temperature of the temperature detecting body is lower than the temperature corresponding to the temperature drop of the heating body based on the time length, the abnormality is detected, and the prohibiting means sets the time elapsed from the stop of heating the heating body to a predetermined time length or less. And when the abnormality detected by the abnormality detecting means is stored in the storage means, the power supply from the power supply to the heating element is prohibited for a predetermined period. The temperature can be detected early, and it is possible to prevent the temperature of the heating element from being excessively raised or the fixing failure due to disconnection or poor contact of the heating element or the heating element.

Further, according to the third aspect of the present invention, the control means changes the power supply cycle per unit time of the power from the power supply to the heating element so that the temperature detected by the temperature detecting element becomes the target temperature. In addition, the prohibiting means controls the power supply from the power supply to the heating element when the elapsed time from the stop of heating of the heating element is equal to or less than the predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means. Because it is prohibited for a predetermined period, it is possible to prevent overheating and fixing failure of the heating element due to disconnection or poor contact of the temperature detecting element or the heating element, and furthermore, it is possible to prevent the temperature of the apparatus from being changed due to the environmental temperature or the power supply voltage. The delay of the warm-up time of the heating element can be prevented.

According to the fourth invention of the present application,
The prohibiting means prohibits the power supply from the power supply to the heating element for a predetermined period when the elapsed time from the stop of heating of the heating element is equal to or less than the predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means. Therefore, it is possible to prevent the temperature of the heating element from being excessively increased or the fixing failure due to disconnection or poor contact of the temperature detecting element or the heating element.

Further, according to the fifth invention of the present application, the abnormality detecting means determines that the time length of the heating stop state from the interruption of power supply to the heating element from the power supply to the re-input is less than the predetermined time length. In some cases, when the detected temperature of the temperature detector is lower than the temperature corresponding to the temperature drop of the heater based on the time length from the detected temperature of the temperature detector when the power is cut off, the abnormality is detected and the prohibition means is provided. However, when the elapsed time from the stop of heating of the heating element is equal to or less than the predetermined time length and the abnormality detected by the abnormality detecting means is stored in the storage means, the power supply from the power supply to the heating element is prohibited for a predetermined period. It is possible to detect an abnormality of the temperature detector or the heating element after the re-input of the power at an early stage, and to prevent an excessive temperature rise or a fixing failure of the heating element due to disconnection or poor contact of the temperature detection element or the heating element. it can.

Further, according to the sixth invention of the present application,
The control means changes the energization cycle per unit time of the power from the power supply to the heating element so that the detected temperature of the temperature detection element becomes the target temperature, and the prohibition means sets the time elapsed from the stop of the heating of the heating element. The power supply from the power supply to the heating element is prohibited for a predetermined period of time when the length of time is equal to or less than the predetermined time and the abnormality detected by the abnormality detecting means is stored in the storage means. Thus, it is possible to prevent the temperature of the heating element from becoming excessively high and to prevent fixing failure, and also to prevent the warm-up time of the heating element from being delayed due to fluctuations in the use environment temperature or the power supply voltage of the apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a fixing device provided in the image forming apparatus of FIG. 1 and a control system thereof.

FIG. 3 is a flowchart illustrating a control system of the fixing device according to the first exemplary embodiment of the present invention.

FIG. 4 is a diagram for explaining control of electric power supplied from a power supply to a heating element according to a second embodiment of the present invention.

FIG. 5 is a flowchart illustrating a control system of a fixing device according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating control of power supplied from a power source to a heating element according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Printer (Image Forming Apparatus) 7 Fixing Device 105 Timer (Heating Time Information Means) 113, 114 Heater (Heating Body) 115, 120 Fixing Roller (Fixing Body, Pressing Body) 116, 117 Temperature Sensor (Temperature Detecting Body) 118 Heating prohibition judging means (prohibiting means, abnormality detecting means) 119 storage means 121 control means P recording medium

Continued on the front page F term (reference) 2H027 DA12 DA39 DA40 DC05 DE01 DE07 DE09 EA12 EC06 EC09 EC10 ED25 EE01 EE07 EE08 EK01 GB07 HA04 HB17 JA11 JC08 2H033 AA02 AA24 AA30 BA08 BA25 BA30 BB01 CA30 CA24 CA24 CA45 CA46 5H323 AA36 BB17 CA09 CB02 FF03 FF10 GG04 KK07 MM02 MM09 NN03 NN15 QQ06 RR01 RR04 SS01 TT02 TT09 9A001 BB06 HH34 JJ35 KK42

Claims (6)

[Claims] A fixing body and a pressurizing body that rotate in pressure contact with each other; a heating body that receives heat from a power source to generate heat and heat at least one of the fixing body and the pressurizing body; A temperature detector for detecting at least one surface temperature of the pressure body; and a control unit for controlling power supply from a power supply to the heating body so that the detected temperature of the temperature detector becomes a target temperature. In a fixing device for fixing the unfixed image to the recording medium by nipping and conveying the recording medium to be carried between the fixing body and the pressing body and applying pressure and heat, at least one of a heating element and a temperature detecting element Abnormality detection means for detecting an abnormality of, heating time information means for obtaining heating time information of heating start and heating stop of the heating element,
A storage unit capable of storing the detected heating time information of the abnormality detection unit and the time information unit; and a real time information, and a predetermined elapsed time from the heating stop based on the real time information and the heating time information. A fixing device comprising: a prohibition unit that prohibits power supply from the power supply to the heating body for a predetermined period when the detection abnormality is shorter than a time length and the detection abnormality is stored in the storage unit. 2. The abnormality detecting means according to claim 1, wherein when the power from the power supply to the heating element is turned off and then turned on again, the time length of the heating stop state from the cutoff to the re-input of the power is a predetermined time length. Set to detect an abnormality when the detected temperature of the temperature detector is lower than the temperature corresponding to the temperature drop of the heater based on the time length from the detected temperature of the temperature detector when the power is cut off when the power is below The fixing device according to claim 1, wherein the fixing device is used. 3. The control device according to claim 1, wherein the control unit is capable of changing an energizing cycle per unit time of electric power from the power supply to the heating element so that the detected temperature of the temperature detection object becomes the target temperature. 3. The fixing device according to 2. 4. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium,
An image forming apparatus comprising the fixing device according to claim 1. 5. The abnormality detecting means, wherein when the power from the power supply to the heating element is cut off and then turned on again, the time length of the heating stop state from the cutoff of the electric power to the turning back on is set to a predetermined time length. Set to detect an abnormality when the detected temperature of the temperature detector is lower than the temperature corresponding to the temperature drop of the heater based on the time length from the detected temperature of the temperature detector when the power is cut off when the power is below The image forming apparatus according to claim 4, wherein 6. The control device according to claim 4, wherein the control unit is capable of changing an energizing cycle of power from the power supply to the heating unit per unit time so that the detected temperature of the temperature detection unit becomes the target temperature. 6. The image forming apparatus according to 5.