JP2012185367A - Image formation apparatus, heating control method, and heating control program - Google Patents

Abstract

An image forming apparatus can be used even during a period of time until repair by a service while preventing a high temperature abnormality of a fixing heater.
When the power is turned on and when returning from the sleep mode (S101), the temperature of the fixing heater is detected (S102), and an AC input voltage is detected by an AC voltage detection circuit (S103). The power duty to the fixing heater corresponding to the detected value is determined and the fixing heater is turned on (S104), and the temperature of the fixing heater N seconds after the power is turned on and after the return to the sleep mode is detected (S105). It is determined whether the temperature of the fixing heater after 2 seconds is within the value range of the temperature prediction table (S106). If it is on, control exits this routine without changing the current fixing control. If it is out of the predicted temperature range, it is determined that the AC input voltage is erroneously detected, and the power duty to the fixing heater is greatly reduced. (S107).
[Selection] Figure 4

Description

  The present invention relates to an image forming apparatus, a heating control method for a fixing device of the image forming apparatus, and a heating control program for executing the heating control method by a computer. In particular, the present invention relates to a copying machine, a printer, a facsimile machine, a digital multifunction machine, and the like. The present invention relates to a technique for dealing with erroneous detection of an input power supply voltage applied to a fixing device of an image forming apparatus.

  In an electrophotographic image forming apparatus, the AC input power supply voltage is detected, and the power input when the heater (heat source) for fixing the toner is turned on depends on the detected input voltage value and the target temperature for fixing the toner. Thus, power is limited by selecting a preset duty, and control without overshoot or power shortage is executed. FIG. 1A is a characteristic diagram showing a “time-temperature” characteristic in the conventional fixing power control. In the case of the prior art, particularly when the fixing heater is cooled, such as when the power is turned on or when returning from the sleep mode, when the AC input voltage is detected as AC 100 V, the fixing heater is turned on at Duty 100% (A Characteristics), when the AC input voltage detection circuit is faulty, etc., and the AC 120V is actually input, the fixing heater is turned on at a duty of 100%. Therefore, even if the energization of the fixing heater is stopped at the heater stop temperature Tsp The heater temperature exceeds the temperature high temperature abnormal threshold temperature Tth (characteristic B). Reference symbol B indicates the measured temperature.

  The high temperature abnormality Tov is a problem related to the safety of the image forming apparatus, and a design that does not cause a high temperature abnormality even when an AC input voltage is erroneously detected is required. Further, when a high temperature abnormality is detected in the image forming apparatus, the image forming apparatus cannot normally be operated until the repair in the service is completed from the viewpoint of safety even if the user turns off / on the power of the image forming apparatus. . For this reason, when a high temperature abnormality occurs, even if it is necessary to use the image forming apparatus, it cannot be used and a burden is imposed on the user.

  Therefore, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2006-039027) proposes an invention in which AC input power supply voltage detection means is provided in front of the heater control circuit to perform control without overshoot or power shortage. Has been.

  However, in the invention described in Patent Document 1, since the emphasis is mainly on increasing the power in order to compensate for the power shortage, the fixing is performed particularly when the fixing heater is cooled, such as when the power is turned on or when the sleep mode is restored. When the heater is turned on, the inrush current increases. As a result, the temperature characteristic of the fixing becomes steep, and if the detected AC input voltage itself is erroneously detected lower than the actual voltage, the AC input voltage actually increases, so the power consumption of the fixing heater increases, and the high temperature It sometimes became abnormal.

  Therefore, the problem to be solved by the present invention is to prevent a high temperature abnormality of the fixing heater even when the AC input voltage is erroneously detected when the fixing heater is cooled, such as when the power is turned on or when the sleep mode is restored. In other words, the image forming apparatus can be used even during repairs.

  In order to solve the above-mentioned problem, the first means is an image forming apparatus including a voltage detection means for detecting an AC input voltage and a temperature detection means for detecting the temperature of the fixing heater, wherein an AC input voltage value is provided. A temperature prediction table storing a temperature prediction value after a predetermined time from power-on and sleep mode recovery, and the fixing after a predetermined time from the power-on and sleep mode recovery detected by the temperature detection means. When the temperature of the heater is within the temperature range set in the temperature prediction table, the temperature of the fixing heater detected by the temperature detection means, the AC input voltage value detected by the voltage detection means, and the temperature prediction table A first control that heats the fixing heater with the currently-executed power duty based on a set temperature prediction value; and that the temperature is out of the temperature range. Is characterized by comprising a control means for executing a second control for heating the fixing heater is changed to increase deviating Duty the power Duty.

  In this case, when the temperature is out of the temperature range and the temperature after a predetermined time from the time of power-on or return from the sleep mode falls below the temperature predicted value in the temperature prediction table, the second control is used instead. The first control is executed. At this time, the apparatus may be configured to stop by setting the greatly deviated duty to 0%.

  Further, when the temperature of the fixing heater after a certain time from the time when the power is turned on and the return to the sleep mode detected by the temperature detecting means is within the temperature range set in the temperature prediction table, a predetermined value is further added. It is determined whether or not the temperature of the fixing heater after the time is within the temperature range set in the temperature prediction table. If the temperature is within the temperature range, the first control is executed to deviate from the temperature range. In this case, the second control may be executed. Further, when executing the second control, the temperature of the fixing heater is detected for a certain period of time, and it is determined whether or not a preset high temperature abnormal threshold temperature at which a probability of occurrence of abnormality is high is reached. When the second control is executed and reached, the apparatus can be stopped by setting the duty to 0%.

  The second means is a heating control method for a fixing heater in an image forming apparatus, comprising: a voltage detecting means for detecting an AC input voltage; and a temperature detecting means for detecting the temperature of the fixing heater. A step of referring to a temperature prediction table storing a temperature prediction value after a predetermined time from power-on and sleep mode recovery for each time, and a predetermined time from the power-on and sleep mode recovery detected by the temperature detection means When the temperature of the subsequent fixing heater is within the temperature range set in the temperature prediction table, the temperature of the fixing heater detected by the temperature detecting means, the AC input voltage value and the temperature detected by the voltage detecting means Heating the fixing heater with the currently executed power duty based on the predicted temperature set in the prediction table; and the temperature range. When off-is characterized by comprising a, a step of heating the fixing heater by changing the power Duty significantly deviating Duty.

  The third means is a heating control for executing the heating control of the fixing heater in the image forming apparatus having a voltage detecting means for detecting the AC input voltage and a temperature detecting means for detecting the temperature of the fixing heater by a computer. A program that refers to a temperature prediction table that stores a predicted temperature value after a certain time from power-on and sleep mode recovery for each AC input voltage value, and the power-on detected by the temperature detection means The temperature of the fixing heater detected by the temperature detecting means when the temperature of the fixing heater after a certain time from the time of returning to the sleep mode is within the temperature range set in the temperature prediction table, the voltage detecting means The power D currently being executed based on the AC input voltage value detected by the temperature prediction value and the temperature prediction value set in the temperature prediction table. and a procedure for heating the fixing heater when the temperature is out of the temperature range, and a step for heating the fixing heater by changing the power duty to a duty greatly deviated. .

  In the embodiments described later, the voltage detection means is the AC voltage detection circuit 26, the fixing heater is 27, the temperature detection means is the thermistor 15, the temperature prediction table is 8a, the control means is the CPU 2, and image formation is performed. The devices correspond to reference numeral 1, respectively.

  According to the present invention, it is possible to prevent an abnormality in the temperature of the fixing heater and to enable the use of the image forming apparatus until repair by service.

It is a characteristic view which shows the relationship between time and temperature when the power control in a prior art example and embodiment of this invention is performed. 1 is a functional block diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows the control structure containing AC (primary side) circuit and its control circuit. 3 is a flowchart illustrating a heating control procedure according to the first embodiment. It is a figure which shows an example of a temperature prediction table. 6 is a flowchart illustrating a heating control procedure in the second embodiment. 10 is a flowchart showing a heating control procedure in Embodiment 3. 10 is a flowchart showing a heating control procedure in Embodiment 4. 10 is a flowchart showing a heating control procedure in Embodiment 5.

  The present invention prepares a temperature prediction table over time for an AC (alternating current) input voltage, and the temperature of the fixing heater at the detected AC input voltage exceeds the temperature predicted from the temperature prediction table over time. Is characterized in that AC input voltage is erroneously detected, and the power duty to the fixing heater is lowered so that an abnormally high temperature does not occur.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a functional block diagram showing the configuration of the image forming apparatus according to the embodiment of the present invention. In FIG. 1, the image forming apparatus 1 is mainly configured by a CPU 2, and under the control of the CPU 2, a (paper) transport unit 3, a paper discharge unit 4, a paper feed unit 5, an image reading unit 6, The image processing unit 7, the memory unit 8, the fixing unit 11, the interface 18, the A / D conversion unit 16, the image forming unit 22, and the like are connected so that signals can be exchanged between them.

  The paper feed unit 5 feeds a recording medium such as paper from the paper feed stage, and transports the image-formed paper to the fixing unit 11 by the transport unit 4 to the image forming unit 22 that forms a visible image on the paper. Then, the paper is discharged from the paper discharge unit 4 to a paper discharge tray or the like. The image reading unit 6 optically reads a document or the like, converts the read optical data into electronic image data, and sends it to the image processing unit 7. The image processing unit 7 processes the image area and image information of the read image data, converts them into image information that can be imaged by the image forming unit 22, and sends the image information to the image forming unit 22. The image forming unit 22 forms a visible image on the sheet based on the received image information. In this embodiment, the image forming unit 22 is assumed to be an electrophotographic image forming engine.

  The fixing unit 11 includes a heat source 13 for melting powder (for example, toner) to be thermally welded to record image information on a presentation medium such as paper, and a heat source control circuit unit 12 for controlling the heat source, and a fixing unit. Thermistor 15 for detecting the temperature of 12 and the A / D converter 14 for A / D converting the detection output of the thermistor 15 and converting it to a digital signal for processing by the CPU 2 are provided.

  The memory unit 8 includes a RAM 10 that temporarily stores a detection voltage and a ROM 9 that permanently stores a fixing control pattern, and an interface 18 is connected to an external communication device 20 such as a personal computer or an external storage element 19 from an image. Capture data. In addition, a voltage detection unit 17 that performs voltage detection in order to perform control without overshoot and power shortage, and an A / D conversion unit 16 that converts the detected analog voltage into a digital signal for processing by the CPU.

  FIG. 3 is a block diagram showing a control configuration including an AC (primary side) circuit and its control circuit. In this control configuration, the CPU 2 and the memory 8 are mounted on the control board 30, and the detection voltage of the AC voltage detection circuit 26 connected to the subsequent stage of the relay 23 connected to the commercial AC power supply 25 is input to the CPU 2. The detection output of the thermistor 15 that detects the temperature of the fixing heater 27 is input to control the relay 23 and the fixing circuit 24.

  Specifically, since the relay that cuts off the AC input from the external commercial AC power supply 25 is turned on when the power is turned on and when the sleep mode is restored, the AC power is supplied to the circuit subsequent to the relay 23. The AC voltage detection circuit 26 detects the AC input voltage and transmits the result to the CPU 2 of the control board 30. The fixing control circuit 24 controls ON / OFF of the fixing heater 27 based on a fixing control (power duty control to the fixing heater) signal from the CPU 2 of the control board 30. The thermistor 15 detects the temperature of the fixing heater 27 and transmits the detected temperature of the fixing heater 27 to the CPU 2 of the control board 30.

  The memory 8 stores a temperature prediction table 8a over time with respect to the AC input voltage, and the temperature of the fixing heater 27 N (N <0) seconds after the power is turned on and the sleep mode is restored by the CPU 2 is the temperature. It is determined whether the temperature matches the predicted temperature in the prediction table 8a, and the fixing control is changed according to the result. The AC voltage detection circuit 26 is included in the voltage detection unit 17 in FIG. 2, and a digital signal from the A / D converter 16 is input to the CPU 2. The fixing heater 27 corresponds to the heat source 13 in FIG. 2, and the fixing control circuit 24 corresponds to the heat source control circuit unit 12.

FIG. 4 is a flowchart showing the heating control procedure of the first embodiment executed by the CPU 2 in the control configuration shown in FIG.
In the figure, when the power is turned on and when returning from the sleep mode (step S101: Yes), the thermistor 15 detects the temperature of the fixing heater 27 (step S102), and the AC voltage detection circuit 26 detects the AC input voltage (step S102). S103). Next, the power duty to the fixing heater corresponding to the detected value is determined, and the fixing heater 27 is turned on (step S104).

  After the fixing heater 27 is turned on, the thermistor 15 detects the temperature of the fixing heater 27 N seconds after the power is turned on and when the sleep mode is restored (step S105). Then, it is determined whether or not the temperature of the fixing heater 27 after N seconds is within the range of the value of the temperature prediction table 8a (step S106). If it is, the current fixing control is not changed. If the routine exits and is outside the range of the predicted temperature value, it is determined that the AC input voltage is erroneously detected, and the control is changed to a control for greatly reducing the power duty to the fixing heater 27 (step S107).

  FIG. 5 is a diagram showing an example of the temperature prediction table 8a referred to in step S106. This table is set as a table with the AC input voltage, the power duty to the fixing heater when the power is turned on and when the sleep mode is restored, and the estimated temperature value of the fixing heater 5 seconds after the power is turned on and when the sleep mode is restored. Has been. FIG. 5 is an example of a temperature prediction table when the temperature of the fixing heater at the time of turning on the power and returning from the sleep mode is normal temperature (25 ° C.). In practice, for example, even in an AC input voltage between 80V AC and 90V AC, which is omitted in FIG. 5, the power duty to the fixing heater and the predicted temperature value of the fixing heater after 5 seconds are set for each 1V.

  For example, when the AC voltage detection circuit 26 detects AC 120 V exceeding AC 100 V, the power Duty to the fixing heater is set to 80% when the power is turned on and the sleep mode is returned in Step S104, and the temperature detected in Step S105. However, if it is determined in step S106 that the temperature is in the range of 105 to 115 ° C., the control is continued as it is. If not, the control in step S107 is executed.

  In this embodiment, the fixing start-up time is delayed, but it is possible to use the image forming apparatus until repair by service while preventing the occurrence of high temperature abnormality.

FIG. 6 is a flowchart showing a heating control procedure in the second embodiment.
In the second embodiment, in step S106 of the first embodiment, it is determined whether the temperature of the fixing heater 27 after N seconds is within the value range of the temperature prediction table 8a. In addition to whether or not the temperature is within the range of the value of the temperature prediction table 8a, if not, it is determined whether or not the temperature of the fixing heater 27 is below the lower limit of the value of the temperature prediction table 8a (step S106a). ) Then, when the temperature of the fixing heater 27 after N seconds is within the range of the value of the temperature prediction table 8a, and when the temperature of the fixing heater 27 is below the lower limit of the value of the temperature prediction table 8a, the temperature is high. It is determined that the abnormal threshold temperature has not been reached, the current control is executed, and if the temperature of the fixing heater 27 is higher than the upper limit of the value of the temperature prediction table 8a, it is determined in step S107 that the AC input voltage is erroneously detected, The control is changed to a control for greatly reducing the power duty to the fixing heater. Other processes are the same as those in the first embodiment.

  In this embodiment, since the power duty reduction control is executed only when the temperature rises, the fixing start-up time is not delayed more than necessary.

FIG. 7 is a flowchart showing a heating control procedure in the third embodiment.
In the third embodiment, it is determined in step S107 of the first embodiment that the AC input voltage is erroneously detected, and the control is changed to a control for greatly reducing the power duty to the fixing heater, whereas the power duty to the fixing heater is set to 0%. This is to be stopped (step S107a). Other processes are the same as those in the first embodiment.

  In this embodiment, when it is determined that there is an abnormality, the fixing heater power is changed to 0% duty and the fixing and image forming apparatus is stopped, so that a high temperature abnormality never occurs.

FIG. 8 is a flowchart showing a heating control procedure in the fourth embodiment.
In the fourth embodiment, it is determined in step S106 of the first embodiment whether the temperature of the fixing heater 27 after N seconds is within the value range of the temperature prediction table 8a. If the temperature is within the range (step S106: In step S106b, the temperature of the fixing heater 27 after N + 1 seconds is determined. That is, if the temperature of the fixing heater 27 after N + 1 seconds is within the value range of the temperature prediction table 8a in step S106b, the current fixing control is not changed (step S106b: Yes), and the predicted temperature value is changed. If it is out of the range (step S106b: No), it is determined that the AC input voltage is erroneously detected, and the control is changed to a control for greatly reducing the power duty to the fixing heater (step S107). Other processes are the same as those in the first embodiment.

  In the present embodiment, since the temperature measurement and the detection result are determined in step S106b, the input voltage erroneous detection can be performed with higher accuracy than in the first embodiment.

FIG. 9 is a flowchart showing a heating control procedure in the fifth embodiment.
In the fifth embodiment, after changing to the control for greatly reducing the power duty to the fixing heater in step S107 of the first embodiment, the temperature of the fixing heater is further detected for a certain period of time to determine whether or not the high temperature abnormal threshold temperature has been reached. If not reached (step S108: No), the control is continued with the duty set in step S107. If reached, the power duty to the fixing heater 27 is changed to 0%, and the machine is turned on. Stop (step S107b). Other processes are the same as those in the first embodiment.

  FIG. 1B is a characteristic diagram showing the relationship between time and temperature when power control is performed in the present embodiment. This characteristic diagram shows that the temperature of the fixing heater 27 does not become higher than the high temperature abnormal threshold temperature Tth, unlike the prior art shown in FIG.

  That is, the range of the curve indicated by the symbol A indicates the temperature characteristics of the temperature prediction table 8a at AC 100 V and Duty 100%, and the curve indicated by the symbol C indicates the characteristics when the control of the first embodiment is executed. From this temperature characteristic, a comparison between the predicted temperature Nt1 after N seconds (5 seconds in FIG. 5) in the temperature prediction table 8a and the detected temperature Nt2 at that time indicates that the temperature is not within the temperature range in step S106. In step S107, if the power duty to the fixing heater is changed to a value that is greatly reduced, or the energization is stopped, the temperature rise after the lapse of time N is suppressed, and the temperature of the fixing heater 27 does not exceed the high temperature abnormal threshold temperature Tth. You can see that

  In this embodiment, the temperature of the fixing heater is detected for a predetermined time in step S108 even after the erroneous detection of the input voltage is detected, and during that time, it is confirmed that the high temperature abnormal threshold temperature is not reached. Can be achieved.

  As described above, in this embodiment, even when the fixing heater 27 is cooled, such as when the power is turned on and when the sleep mode is restored, which is particularly severe, high temperature abnormality can be prevented when AC input voltage is erroneously detected. . In this embodiment, AC 100 V is detected in the AC input voltage detection. However, when AC 120 V is actually input, the fixing heater 27 is turned on with a duty of 100% when the power is turned on and when the sleep mode is restored. The temperature of the fixing heater 27 is measured N seconds (for example, after 5 seconds) after the return to the sleep mode, and after N seconds in the AC100V Duty 100% read from the temperature prediction table 8a prepared in the image forming apparatus 1. Compared with the predicted temperature value, the current fixing control is not changed if it is within the predicted temperature value range. If it is outside the predicted temperature value range, it is determined that the AC input voltage is erroneously detected, and the fixing duty is increased. Change to lowering (for example, Duty 40%) control. As a result, the fixing start-up time (time until printing becomes possible) is delayed, but the image forming apparatus can be used until repair by service while preventing the occurrence of high temperature abnormality. Needless to say, the AC input voltage erroneous detection itself needs to be permanently repaired.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and all technical matters included in the technical idea described in the claims are included. The subject of the present invention. Each of the above examples shows a preferred embodiment, but those skilled in the art will realize various alternatives, modifications, variations, and improvements from the contents disclosed in this specification. Which fall within the scope defined by the appended claims.

1 Image forming apparatus 2 CPU
8a Temperature prediction table 15 Thermistor 26 AC voltage detection circuit 27 Fixing heater

JP 2006-039027 A

Claims (7)

Voltage detecting means for detecting an AC input voltage;
Temperature detection means for detecting the temperature of the fixing heater;
An image forming apparatus comprising:
A temperature prediction table storing temperature prediction values after a certain period of time from power ON and sleep mode recovery for each AC input voltage value;
When the temperature of the fixing heater after a certain time from the time of turning on the power and returning from the sleep mode detected by the temperature detection means is within the temperature range set in the temperature prediction table, the temperature detection means Based on the detected temperature of the fixing heater, the AC input voltage value detected by the voltage detection means, and the temperature prediction value set in the temperature prediction table, the first fixing heater is heated with the currently executed power duty. Control means for executing control and second control for heating the fixing heater by changing the power duty to a duty greatly deviated when out of the temperature range;
An image forming apparatus comprising: The image forming apparatus according to claim 1,
If the temperature falls outside the temperature range, and the temperature after a certain period of time after power-on or sleep mode recovery falls below the temperature predicted value in the temperature prediction table, the first control is used instead of the second control. An image forming apparatus that executes control. The image forming apparatus according to claim 1, wherein:
2. The image forming apparatus according to claim 1, wherein the greatly deviated duty is 0%. The image forming apparatus according to claim 1,
When the temperature of the fixing heater after a predetermined time from the time when the power is turned on and the return to the sleep mode detected by the temperature detecting means is within the temperature range set in the temperature prediction table, a further predetermined time later It is determined whether or not the temperature of the fixing heater is within the temperature range set in the temperature prediction table. When the temperature is within the temperature range, the first control is executed and the temperature is out of the temperature range. Is an image forming apparatus that executes the second control. The image forming apparatus according to claim 1,
When executing the second control, the temperature of the fixing heater is detected for a certain period of time, and it is determined whether or not a preset high-temperature abnormal threshold temperature at which there is a high probability of occurrence of an abnormality has been reached. The image forming apparatus is characterized in that the control is executed, and when reached, the apparatus is stopped by setting the duty to 0%. Voltage detecting means for detecting an AC input voltage;
Temperature detection means for detecting the temperature of the fixing heater;
A heating control method for a fixing heater in an image forming apparatus comprising:
A step of referring to a temperature prediction table storing a temperature prediction value after a predetermined time from power-on and sleep mode recovery for each AC input voltage value;
When the temperature of the fixing heater after a predetermined time from the time when the power is turned on and the return to the sleep mode detected by the temperature detection means is within the temperature range set in the temperature prediction table, the temperature detection means detects the temperature. Heating the fixing heater with the power duty currently being executed based on the temperature of the fixing heater, the AC input voltage value detected by the voltage detection means, and the temperature prediction value set in the temperature prediction table;
When the temperature is out of the temperature range, changing the power duty to a duty greatly deviating and heating the fixing heater;
A heating control method for a fixing heater, comprising: Voltage detecting means for detecting an AC input voltage;
Temperature detection means for detecting the temperature of the fixing heater;
A heating control program for executing heating control of a fixing heater in an image forming apparatus provided with a computer,
A procedure for referring to a temperature prediction table storing temperature prediction values after a certain time from power-on and sleep mode recovery for each AC input voltage value;
When the temperature of the fixing heater after a predetermined time from the time when the power is turned on and the return to the sleep mode detected by the temperature detection means is within the temperature range set in the temperature prediction table, the temperature detection means detects the temperature. A step of heating the fixing heater with the currently executed power Duty based on the temperature of the fixing heater, the AC input voltage value detected by the voltage detection means, and the temperature prediction value set in the temperature prediction table;
A procedure for heating the fixing heater by changing the power duty to a duty greatly deviating when the temperature falls outside the temperature range;
A heating control program for a fixing heater, comprising:

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