JP2008089974A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is capable of instantaneously detecting abnormality of a non-contact temperature sensor and of correcting dirt of a lens portion or restoring functions when the lens portion is stained. <P>SOLUTION: A thermopile 40 and a thermistor 21 capable of measuring a plurality of areas 25 and 26 are used together, and neighbors of a temperature measurement area 25 of the thermistor 21 are measured by the thermopile 40 also, and measurement results of the thermopile 40 are corrected in accordance with a difference between outputs of the thermopile 40 and the thermistor 21, and the thermopile 40 or the thermistor 21 is determined to be abnormal when the difference between outputs of the thermopile 40 and the thermistor 21 exceeds a prescribed value, and functions are restored when the abnormality of the thermopile 40 is detected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, for example, an electrophotographic image forming apparatus.

  FIG. 9 includes image forming units of four colors, that is, yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), cyan (hereinafter referred to as C), and black (hereinafter referred to as K). 1 shows a color image forming apparatus. In the figure, 1 is a photosensitive drum for forming an electrostatic latent image (a, b, c, and d are for Y, M, C, and K, respectively), and 6a to 6d are driving the photosensitive drums 1a to 1d. Motor.

  2 is a laser scanner that performs exposure in accordance with an image signal to form an electrostatic latent image on the photosensitive drum 1, 3 is an endless conveying belt that sequentially conveys paper to each color image forming unit, and 4 is a motor and gear. These are drive rollers that are connected to drive means such as for driving the conveyor belt 3. 6e is a motor for driving the driving roller 4, 5 is a fixing device for melting and fixing the toner transferred to the paper, 6f is a motor for driving the fixing roller 22 of the fixing device 5, and 7 is a print medium discriminator. A print medium sensor 8 is a paper feed cassette.

  Data to be printed is sent from the personal computer to the printer. When image formation according to the printer engine system is completed and the printer is ready, paper as a printing medium is supplied from the paper feed cassette 8 and reaches the conveyor belt 3. Then, the conveyance belt 3 sequentially conveys the sheet to each color image forming unit. The image signals of the respective colors are sent to the respective laser scanners 2 in synchronization with the conveyance of the paper by the conveyance belt 3, and an electrostatic latent image is formed on the photosensitive drum 1, and the electrostatic latent image is converted into toner by a developing device (not shown). And is transferred onto a sheet by a transfer unit (not shown). In the figure, images are sequentially formed in the order of Y, M, C, and K. Thereafter, the paper is separated from the conveyance belt 3, and the toner image is fixed on the paper by heat by the fixing device 5 and discharged to the outside.

  In the image forming apparatus configured as described above, the temperature of the fixing device 5 is measured and temperature control is performed so as to obtain a desired temperature. A non-contact type temperature sensor such as a thermopile is used as a temperature sensor having relatively good response and accuracy without damaging the surface of the fixing roller. FIG. 10 shows the structure of a thermopile 200 as an example of a non-contact temperature sensor. Basically, the temperature of the internal heat-sensitive element is changed by the infrared rays transmitted through the lens 201 serving as an infrared transmission window, and an output corresponding to the temperature is obtained. In the case of the thermopile 200, the thermosensitive element is the laminated thermocouple 202. Due to infrared radiation between the DUT 204 and the laminated thermocouple 202, the temperature of the hot junction of the laminated thermocouple 202 changes, and a voltage corresponding to the temperature difference from the cold junction of the laminated thermocouple 202 is generated. The temperature of the cold junction can be obtained by measuring the temperature of the cold junction using another thermosensitive element such as the thermistor 203 and adding the temperature difference between the cold junction and the hot junction to the temperature of the cold junction. it can.

  In addition, a temperature sensor that can measure the temperatures of a plurality of areas individually by providing a plurality of independent thermal elements inside has been put into practical use.

However, in order to measure the temperature by heating the thermosensitive element inside the sensor with infrared rays, if the infrared condensing lens of the non-contact temperature sensor is contaminated, an error occurs in the temperature measurement result. In view of this, methods for correcting dirt on a lens of a non-contact type temperature sensor and detecting an abnormality of the sensor have been proposed (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent Laid-Open No. 5-100591 JP-A-5-149790

  However, the correction method or abnormality detection method has the following disadvantages.

  First, consider a conventional example including a non-contact temperature sensor and a temperature sensor for temperature compensation. In this case, when the temperature measurement result of one sensor is out of a predetermined allowable range (the allowable range determined by the temperature measurement result of the other sensor), a conventional method for determining an abnormality or a temperature rise curve of the fixing roller There is a method to detect abnormalities. However, in both cases, it takes time to detect an abnormality, and the accuracy cannot be increased.

  In addition, a contact-type temperature sensor and a non-contact-type temperature sensor are provided. When the fixing roller is stopped, the contact-type temperature sensor is brought into contact with the fixing roller, the temperature is measured, and compared with the output of the non-contact-type temperature sensor. There is a method for correcting a decrease in output due to contamination of the temperature sensor. This method has the following problems. That is, a contact-type temperature sensor and its contact / separation mechanism are required, resulting in an increase in cost and an increase in body size. In addition, there is a disadvantage that measurement with a contact temperature sensor can be performed only when the roller is stopped.

  Furthermore, there is a disadvantage that even if the occurrence of dirt on the lens of the non-contact temperature sensor is detected, it cannot be recovered.

  In view of the above, the present invention provides an image forming apparatus capable of immediately detecting an abnormality of a non-contact temperature sensor, correcting a stain on a lens unit, and recovering a function.

  The present invention has been made to solve the above-described problems, and includes the following configuration.

  A non-contact temperature sensor capable of measuring a plurality of areas and a contact temperature sensor are used together, and the vicinity of the measurement area of the contact temperature sensor is also measured by the non-contact temperature sensor. Then, the measurement result of the non-contact temperature sensor is corrected according to the difference between the outputs of the non-contact temperature sensor and the contact temperature sensor, and the difference between the outputs of the non-contact temperature sensor and the contact temperature sensor is a predetermined value. If exceeded, it is determined that the temperature sensor is abnormal. In addition, when an abnormality is detected in the non-contact temperature sensor, the function is restored.

  That is, the technical contents of the present invention can solve the above-described problems by including the following configuration.

  (1) The temperature of the object to be heated is determined based on the heat source, the object to be heated by the heat source, the temperature measuring unit for measuring the temperature of the object to be heated, and the temperature measurement result by the temperature measuring unit. In an image forming apparatus including a heat source control unit that controls the heat source so as to reach a target temperature, the temperature measurement unit can measure a non-contact temperature sensor that can measure a plurality of areas, and a single area. An image forming apparatus comprising at least one contact-type temperature sensor, wherein the non-contact-type temperature sensor measures a temperature measurement location by the contact-type temperature sensor or the vicinity of the temperature measurement location.

  (2) The difference between the temperature measured by the contact-type temperature sensor and the temperature measured by the contact-type temperature sensor or the temperature measured by the non-contact-type temperature sensor in the vicinity of the temperature measurement location. The image forming apparatus according to (1), wherein the temperature measurement result by the non-contact temperature sensor is corrected according to the above.

  (3) The heat source control means has a difference between a temperature measured by the contact-type temperature sensor and a temperature measured by the contact-type temperature sensor or a temperature measured by the non-contact-type temperature sensor in the vicinity of the temperature measurement location. When the determined threshold value is exceeded, it is determined that the contact-type temperature sensor or the non-contact-type temperature sensor is abnormal. The image forming apparatus according to (1),

  (4) The heat source control means determines that the non-contact temperature sensor is abnormal when a difference between the temperature measurement results of the plurality of areas measured by the non-contact temperature sensor exceeds a predetermined threshold. The image forming apparatus according to (1), wherein:

  (5) At least two or more of the non-contact temperature sensors are provided, the same area is measured by a plurality of the non-contact temperature sensors, and the difference in temperature measured by the respective non-contact temperature sensors is measured. The image forming apparatus according to any one of (1) to (4), wherein the heat source control unit determines that the non-contact temperature sensor is abnormal when the value exceeds a predetermined threshold.

  (6) The image forming apparatus according to (1), further including recovery means for recovering an abnormality of the non-contact temperature sensor, wherein the recovery means includes a temperature measured by the contact temperature sensor, the contact type When the difference between the temperature measurement location by the temperature sensor or the temperature measured by the non-contact temperature sensor in the vicinity of the temperature measurement location exceeds a predetermined threshold, or when the plurality of the non-contact temperature sensors measure An image forming apparatus that operates when a difference in temperature measurement results between areas exceeds a predetermined threshold value.

  (7) In the image forming apparatus according to (1), the image forming apparatus includes a recovery unit that recovers the abnormality of the non-contact temperature sensor, and the recovery unit includes a film, a roller around which the film is wound, A roller for winding the film; and a driving means for driving the winding roller, wherein the film is disposed between the non-contact temperature sensor and the object to be heated, and the recovery means is the contact The difference between the temperature measured by the temperature sensor and the temperature measured by the contact temperature sensor or the temperature measured by the non-contact temperature sensor in the vicinity of the temperature measurement location exceeds a predetermined threshold, or When the difference between the temperature measurement results of the plurality of areas measured by the non-contact temperature sensor exceeds a predetermined threshold, the roller for winding is determined for a predetermined time. Which was driven at a speed, the image forming apparatus characterized by winding the film determined amount.

  (8) The image forming apparatus according to (7), wherein the film is a material that transmits infrared rays.

  (9) The image forming apparatus according to (6) or (7), wherein the recovery unit operates for each predetermined period or for each predetermined number of printed sheets.

  (10) The image forming apparatus according to (6) or (7), wherein the recovery unit operates when the power is turned on, when the unit of the image forming unit is cleaned, or when the calibration operation is executed. .

  According to the present invention, there is provided an image forming apparatus capable of immediately correcting the influence of lens contamination of a non-contact type temperature sensor and detecting an abnormality, and capable of recovering the function.

  Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

  The configuration of the image forming apparatus according to the embodiment of the present invention is the same as that shown in FIG. In the figure, the temperature measurement is performed by the present invention for the temperature measurement unit of the fixing roller 22. Since other configurations and operations are the same as those of the conventional example, the description thereof is omitted.

  FIG. 2 is a schematic block diagram of the control system of the image forming apparatus according to the present embodiment.

  Reference numeral 101 denotes a printer as an image forming apparatus. Reference numeral 102 denotes a printer control unit (corresponding to heat source control means) that controls each device in the printer 101. A power source 103 supplies power to each device in the printer 101. Reference numeral 104 denotes sensors for measuring the status of each unit in the printer 101. A motor control unit 105 controls the motors according to instructions from the printer control unit 102. Reference numerals 106 denote motors that are power sources of the respective devices in the printer 101. A display unit 107 notifies the user of the operation status of the printer 101. Reference numeral 108 denotes a high voltage power source. A communication controller 109 performs communication between the printer 101 and the host computer. A host computer 110 transfers data to be printed to the printer 101.

  FIG. 1 is an explanatory diagram showing a configuration of a main part according to the present embodiment.

  Reference numeral 40 denotes a non-contact temperature sensor, and here, a thermopile is used. Of course, the present invention is not limited to the use of a thermopile, and a thermistor, a diode, or the like may be used as a thermal element inside the sensor. Hereinafter, the non-contact temperature sensor 40 is referred to as a thermopile 40.

  21 is a thermistor of a contact type temperature sensor. Reference numeral 22 denotes a fixing roller as an object to be heated, and reference numerals 23 and 24 denote halogen heaters as heat sources for heating the fixing roller 22. A main heater 23 mainly heats the central portion of the fixing roller 22, and a sub heater 24 heats an end portion of the fixing roller 22. Hereinafter, the halogen heaters 23 and 24, or the main heater 23 and the sub heater 24 are used. The fixing roller 22 is heated by halogen heaters 23 and 24. The temperature of the fixing roller 22 is measured by the thermopile 40 and the thermistor 21, and the input power to the halogen heaters 23 and 24 is adjusted so that the temperature of the fixing roller 22 becomes a desired temperature.

  FIG. 3 shows a cross-sectional view of the main part of the thermopile 40. Inside the thermopile 40 as a sensor, there are two independent stacked thermocouples 27 and 28. Reference numeral 29 denotes a lens that transmits infrared rays. Infrared radiation is emitted between two areas (to be described later) of the DUT 304 and between the two laminated thermocouples 27 and 28, so that the temperature of the two areas can be measured. The laminated thermocouples 27 and 28 are provided on a base having good thermal conductivity so that the cold junction temperatures of the two are equal. A thermistor 30 is provided on the base and measures the temperature of the cold junction of the laminated thermocouples 27 and 28.

  In FIG. 1, 25 and 26 are temperature measurement areas of the thermopile 40, and the temperature measurement area 25 is in the vicinity of the temperature measurement location of the thermistor 21. More preferably, the same circumference of the fixing roller 22 is measured. The temperature measurement area 26 is a portion heated by the heat generating portion H of the main heater 23 of the fixing roller 22, for example, near the center of the fixing roller 22.

  FIG. 4 is a schematic sectional view showing the positional relationship between the thermistor 21 and the fixing roller 22. A thermistor chip 33 is mounted on a plate spring 32 extending from the base portion 31, and the plate spring 32 is pressed against the fixing roller 22. This spring property ensures contact with the fixing roller 22, so that stable temperature measurement can be performed. The thermistor 21 is arranged at the end of the fixing roller 22 where the paper on the fixing roller 22 does not pass.

  Next, the operation will be described.

  The printer control unit 102 supplies power to the halogen heaters 23 and 24 based on temperature information from the thermopile 40 and the thermistor 21 (hereinafter also simply referred to as a temperature sensor) so that the fixing roller 22 has a desired temperature. Control.

  The main heater 23 is controlled based on the temperature measurement result at the center of the fixing roller 22, and the sub-heater 24 is controlled based on the temperature measurement result at the end of the fixing roller 22.

  A value obtained by converting the output of each temperature sensor into a temperature by the printer control unit 102 is used as a temperature measurement result. To convert each temperature sensor output to a temperature, a conversion table stored in advance in the printer control unit 102 or an arithmetic expression may be used.

  The temperature measurement result of the end measured by the thermopile 40 is compared with the temperature measurement result of the end measured by the thermistor 21, and when the difference Δt is equal to or less than a predetermined value α, the temperature measurement of the center measured by the thermopile 40 is performed. Correct the results.

  In addition, when the temperature measurement result of the edge part which the thermopile 40 measured is lower than the temperature measurement result of the edge part which the thermistor 21 measured, it correct | amends. On the other hand, if it is high, it is considered that a failure such as floating of the thermistor 21 has occurred. Therefore, it is determined that the sensor system of the thermopile 40 or the thermistor 21 is abnormal, and the operation of the printer is stopped.

The correction method will be described below. First, FIG. 5 shows temperature measurement results when the lens 29 of the thermopile 40 is normal (solid line) and when the lens 29 is dirty (broken line). As shown in FIG. 5, when the lens 29 is normal, the relationship between the actual temperature T and the temperature measurement result t of the thermopile 40 is
t = T
It becomes.

On the other hand, when the lens 29 is dirty, the relationship between the actual temperature T and the temperature measurement result t of the thermopile 40 is
t = a × T + b
It becomes. Here, a is a numerical value of 1 or less, and b is a value corresponding to the cold junction temperature of the thermopile 40. In addition, since the dirt of the lens 29 adheres uniformly to the lens surface in a normal use state, the difference between the temperature measurement results of the two temperature measurement areas 25 and 26 and the actual temperature of each area is different. Occur almost the same way.

  As a correction method, the values of a and b are calculated from the temperature measurement result of the end measured by the thermopile 40, the cold junction temperature of the thermopile 40, and the temperature measurement result of the end measured by the thermistor 21. And the temperature measurement result of the center part which the thermopile 40 measured is correct | amended based on the calculated value of a and b.

  For example, when the temperature measurement result of the end measured by the thermistor 21 is 160 ° C., the temperature measurement result of the end measured by the thermopile 40 is 154.5 ° C., and the cold junction temperature of the thermopile 40 is 50 ° C., a = 0 .95, b = 2.5. At this time, if the temperature measurement result of the central part measured by the thermopile 40 is 173.5 ° C., the corrected temperature of the central part is 180 ° C.

  Or it can correct | amend to the extent which is practically satisfactory even if it correct | amends simply from ratio of T and t.

  For example, in a simple method, when the temperature measurement result of the end measured by the thermistor 21 is 160 ° C. and the temperature measurement result of the end measured by the thermopile 40 is 154.5 ° C., the ratio between the two is about 0. 966. At this time, if the temperature measurement result of the central portion measured by the thermopile 40 is 173.5 ° C., the temperature of the central portion corrected by the ratio is 179.7 ° C.

  If Δt is equal to or greater than the predetermined value β, it is determined that the sensor system of the thermopile 40 or the thermistor 21 is abnormal, and the printer operation is stopped.

  When it is determined that the sensor system of the thermopile 40 or the thermistor 21 is abnormal and the printer operation is stopped, the display unit 107 may display a message indicating that there is an abnormality in the sensor system or a message prompting the inspection of the sensor system.

  A second embodiment of the present invention will be described.

  Since the configuration of the image forming apparatus of this embodiment and the schematic configuration of the control system are the same as those of the first embodiment, description thereof is omitted.

  FIG. 6 shows a configuration of a main part according to the present embodiment.

  41 is a thermopile of a non-contact type temperature sensor, and 21 is a thermistor of a contact type temperature sensor. Reference numeral 22 denotes a fixing roller as an object to be heated, and reference numerals 23 and 24 denote halogen heaters as heat sources for heating the fixing roller 22. A main heater 23 mainly heats the central portion of the fixing roller 22, and a sub heater 24 heats an end portion of the fixing roller 22. The fixing roller 22 is heated by halogen heaters 23 and 24. The temperature of the fixing roller 22 is measured by the thermopile 41 and the thermistor 21, and the input power to the halogen heaters 23 and 24 is adjusted so that the temperature of the fixing roller 22 becomes a desired temperature.

  The basic structure of the thermopile 41 is the same as that of the first embodiment, and there are four temperature measurement areas 34 to 37. Inside the thermopile 41 as a sensor, there are four independent laminated thermocouples, and infrared radiation is performed between the four areas of the object to be measured and the four laminated thermocouples. Temperature measurement is possible.

  One of the temperature measurement areas 34 of the thermopile 41 is in the vicinity of the temperature measurement location of the thermistor 21. More preferably, the same circumference is measured. The remaining temperature measurement areas 35 to 37 are arranged in a range heated by the main heater 23 of the fixing roller 22.

  The structure of the thermistor 21 is the same as that of the first embodiment, and a description thereof will be omitted. The thermistor 21 is disposed on the fixing roller 22 at the end of the fixing roller 22 through which no paper passes.

  Next, the operation will be described.

  The printer control unit 102 controls the power supplied to the halogen heaters 23 and 24 based on the temperature information from the temperature sensor so that the fixing roller 22 has a desired temperature.

  The main heater 23 is controlled based on the temperature measurement result at the center of the fixing roller 22, and the sub heater 24 is controlled based on the temperature measurement result at the end.

  As the temperature measurement result at the center of the fixing roller 22, an average value or a weighted average value of the temperature measurement results of the temperature measurement areas 35 to 37 of the thermopile 41 may be used, or the temperature measurement results of the temperature measurement areas 35 to 37 may be used. The temperature having the highest temperature measurement result may be extracted and used.

  Further, the temperature measurement result of the end measured by the thermopile 41 is compared with the temperature measurement result of the end measured by the thermistor 21, and if the difference is equal to or greater than a predetermined value, the sensor system of the thermopile 41 or the thermistor 21 is compared. The printer is judged to be abnormal and the printer operation is stopped. Or when the dispersion | variation in the temperature measurement result of each temperature measurement area 35-37 of the thermopile 41 is more than a predetermined value, it judges that the thermopile 41 is abnormal and stops the operation of the printer.

  When it is determined that the sensor system is abnormal and the printer operation is stopped, the display unit 107 may display a message that there is an abnormality in the sensor system or a message that prompts inspection of the sensor system.

  A third embodiment of the present invention will be described.

  Since the configuration of the image forming apparatus of this embodiment and the schematic configuration of the control system are the same as those of the first embodiment, description thereof is omitted.

  FIG. 7 shows a configuration of a main part according to the present invention.

  40 and 42 are thermopiles of a non-contact temperature sensor, and 21 is a thermistor of a contact temperature sensor. Reference numeral 22 denotes a fixing roller as an object to be heated, and reference numerals 23 and 24 denote halogen heaters as heat sources for heating the fixing roller 22. A main heater 23 mainly heats the central portion of the fixing roller 22, and a sub heater 24 heats an end portion of the fixing roller 22. The fixing roller 22 is heated by halogen heaters 23 and 24. The temperature of the fixing roller 22 is measured by the thermopiles 40 and 42 and the thermistor 21, and the input power to the halogen heaters 23 and 24 is adjusted so that the temperature of the fixing roller 22 becomes a desired temperature.

  The thermopile 40, 42 is a thermopile having two temperature measurement areas, and the configuration thereof is the same as that of the first embodiment, so that the description thereof is omitted.

  One temperature measurement area 25 of the thermopile 40 is in the vicinity of the temperature measurement portion of the thermistor 21. More preferably, the same circumference is measured. One of the temperature measurement areas 26 of the thermopile 40 is arranged in a range heated by the main heater 23 of the fixing roller 22.

  One of the temperature measurement areas of the thermopile 42 overlaps the temperature measurement area 26 of the thermopile 40.

  One of the temperature measurement areas 38 of the thermopile 42 is arranged in a range heated by the sub heater 24 of the fixing roller 22.

  The structure of the thermistor 21 is the same as that of the first embodiment, and a description thereof will be omitted. The thermistor 21 is disposed at the end of the fixing roller 22 where the paper on the fixing roller 22 does not pass.

  Next, the operation will be described.

  The printer control unit 102 controls the power supplied to the halogen heaters 23 and 24 based on the temperature information from the temperature sensor so that the fixing roller 22 has a desired temperature.

  The main heater 23 is controlled based on the temperature measurement result at the center of the fixing roller 22, and the sub-heater 24 is controlled based on the temperature measurement result at the end of the fixing roller 22. As the temperature measurement result at the center of the fixing roller 22, an average value of the temperature measurement results in the temperature measurement area 26 of the thermopile 40, 42 may be used, or the temperature measurement result of the temperature measurement area 26 of the thermopile 40, 42 may be used. You may extract and use the one where temperature is higher.

  As the temperature measurement result at the end of the fixing roller 22, an average value or a weighted average value of the temperature measurement result of the thermistor 21 and the temperature measurement result of the temperature measurement area 38 of the fixing roller 22 of the thermopile 42 may be used. Further, the higher one of the temperature measurement results may be extracted and used.

  The temperature measurement result of the end measured by the thermopile 40, 42 is compared with the temperature measurement result of the end measured by the thermistor 21, and if the difference is a predetermined value or more, the sensor system of the thermopile 40, 42 or the thermistor 21 is compared. The printer operation is stopped.

  If the variation in the temperature measurement result at the center of the thermopile 40, 42 is greater than or equal to a predetermined value, it is determined that the sensor system of the thermopile 40, 42 is abnormal, and the printer operation is stopped.

  When it is determined that there is no abnormality in the thermopiles 40 and 42 due to the above two conditions, the temperature measurement results of the temperature measurement areas 25 and 38, or the temperature measurement results of the thermistor 21 and the temperature measurement results of the temperature measurement areas 25 and 38. If the difference is greater than or equal to a predetermined value, the following is performed. That is, it is determined that there is an abnormality in the heating of the fixing roller 22, and the operation of the printer is stopped.

  When it is determined that the sensor system of the thermopile 40 or 42 or the thermistor 21 is abnormal and the printer operation is stopped, the display unit 107 may display a message indicating that the sensor system is abnormal or prompting the inspection of the sensor system. Good.

  When it is determined that there is an abnormality in heating of the fixing roller 22 and the printer operation is stopped, a message to that effect may be displayed on the display unit 107.

  A fourth embodiment of the present invention will be described.

  Since the configuration of the image forming apparatus of this embodiment and the schematic configuration of the control system are the same as those of the first embodiment, description thereof is omitted.

  FIG. 8 shows a configuration of a main part according to the present invention.

  40 is a thermopile of a non-contact type temperature sensor, and 21 is a thermistor of a contact type temperature sensor. Reference numeral 22 denotes a fixing roller as an object to be heated, and reference numerals 23 and 24 denote halogen heaters as heat sources for heating the fixing roller 22. A main heater 23 mainly heats the central portion of the fixing roller 22, and a sub heater 24 heats an end portion of the fixing roller 22. The fixing roller 22 is heated by halogen heaters 23 and 24. The temperature of the fixing roller 22 is measured by the thermopile 40 and the thermistor 21, and the input power to the halogen heaters 23 and 24 is adjusted so that the temperature of the fixing roller 22 becomes a desired temperature.

  50 and 51 are rollers, 52 is a roller driving unit (corresponding to a driving means) that rotates the roller 50, 53 is a film, and these are equivalent to recovery means. The film 53 is wound around the roller 51, and the roller 50 is rotated. As a result, the roller 50 is wound up. The film 53 is preferably a film made of a material having a relatively high infrared transmittance. For example, a polyethylene film or the like is used. The film 53 is provided between the thermopile 40 and the fixing roller 22. For example, it is desirable to arrange in front of the lens 29 of the thermopile 40.

  Since the thermistor 21 and the thermopile 40 have the same structure as that of the first embodiment, the description thereof is omitted.

  Next, the operation will be described.

  The printer control unit 102 controls the electric power supplied to the halogen heaters 23 and 24 based on the temperature information from the temperature sensor so that the fixing roller 22 has a desired temperature.

  The main heater 23 is controlled based on the temperature measurement result at the center of the fixing roller 22, and the sub-heater 24 is controlled based on the temperature measurement result at the end of the fixing roller 22.

  The temperature measurement result of the end measured by the thermopile 40 is compared with the temperature measurement result of the end measured by the thermistor 21, and when the difference Δt is equal to or less than a predetermined value α, the temperature measurement of the center measured by the thermopile 40 is performed. Correct the results. Since the correction method is the same as that of the first embodiment, description thereof is omitted.

  When the temperature measurement result at the end by the thermopile 40 is higher, it is considered that a failure such as the thermistor 21 has floated. Therefore, it is determined that the sensor system of the thermopile 40 or the thermistor 21 is abnormal, and the operation of the printer is stopped. .

  When Δt is equal to or larger than the predetermined value β, the roller driving unit 52 is driven to wind up the film 53 by a predetermined amount. The amount of the film 53 taken up is at least the width of the visual field of the thermopile 40. Or it is good also as the quantity from which (DELTA) t will be less than predetermined value (beta) within the width | variety of the visual field of the thermopile 40. FIG. In this case, consumption of the film 53 can be suppressed.

  Even after winding a predetermined amount of film 53, if Δt is equal to or larger than a predetermined value β, it is determined that the thermopile 40 is abnormal and the operation of the printer is stopped.

  When Δt becomes less than the predetermined value β after winding the film 53, the temperature measurement result at the center measured by the thermopile 40 is corrected according to Δt. When the temperature measurement result at the end by the thermopile 40 is lower, the temperature measurement result at the center by the thermopile 40 is corrected. Since the correction method is the same as that of the first embodiment, description thereof is omitted. When the temperature measurement result at the end by the thermopile 40 is higher, it is considered that a failure such as the thermistor 21 has floated. Therefore, it is determined that the sensor system of the thermopile 40 or the thermistor 21 is abnormal, and the operation of the printer is stopped. .

  In the first to fourth embodiments, a single thermistor 21 that is a contact temperature sensor has been described. However, the present invention is not limited to this.

Explanatory drawing which shows the structure of the principal part which concerns on Example 1. FIG. FIG. 1 is a schematic configuration block diagram of a control system for an image forming apparatus according to a first embodiment. Cross-sectional view of the main part of the thermopile according to Example 1 FIG. 3 is a schematic cross-sectional view illustrating the positional relationship between the thermistor and the fixing roller according to the first embodiment. A graph showing the relationship between actual temperature and thermopile temperature measurement results when the thermopile lens is normal (solid line) and when the lens is dirty (dashed line) Explanatory drawing which shows the structure of the principal part which concerns on Example 2. FIG. Explanatory drawing which shows the structure of the principal part which concerns on Example 3. FIG. Explanatory drawing which shows the structure of the principal part which concerns on Example 4. FIG. Schematic configuration sectional view for explaining the entire image forming apparatus The figure explaining the non-contact-type temperature sensor of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Laser scanner 3 Conveyor belt 4 Drive roller 5 Fixing device 6 Motor 7 Print medium sensor 8 Paper feed cassette 21 Thermistor (equivalent to a contact temperature sensor)
22 Fixing roller (equivalent to heated object)
23 Main heater (equivalent to heat source)
24 Sub-heater (equivalent to heat source)
25 temperature measurement area 26 temperature measurement area 27 laminated thermocouple 28 laminated thermocouple 29 lens 30 thermistor 31 base 32 leaf spring 33 thermistor chip 34 temperature measurement area 35 temperature measurement area 36 temperature measurement area 37 temperature measurement area 38 temperature measurement area 40 Thermopile (equivalent to non-contact temperature sensor)
41 Thermopile (equivalent to non-contact temperature sensor)
42 Thermopile (equivalent to non-contact temperature sensor)
50 rollers (equivalent to recovery means)
51 rollers (equivalent to recovery means)
52 Roller drive (equivalent to recovery means and drive means)
53 film (equivalent to recovery means)
101 Printer 102 Printer control unit (corresponding to heat source control means)
DESCRIPTION OF SYMBOLS 103 Power supply 104 Sensors 105 Motor control part 106 Motors 107 Display part 108 High voltage power supply 109 Communication controller 110 Host computer

Claims (10)

Based on the heat source, the object to be heated by the heat source, the temperature measuring means for measuring the temperature of the object to be heated, and the temperature measurement result by the temperature measuring means, the temperature of the object to be heated is the target temperature. In an image forming apparatus comprising a heat source control means for controlling the heat source so that
The temperature measuring means has at least one or more of a non-contact temperature sensor capable of measuring a plurality of areas and a contact temperature sensor capable of measuring a single area,
The image forming apparatus, wherein the non-contact temperature sensor measures a temperature measurement location by the contact temperature sensor or the vicinity of the temperature measurement location.   The heat source control means according to a difference between a temperature measured by the contact temperature sensor and a temperature measured by the contact temperature sensor or a temperature measured by the non-contact temperature sensor in the vicinity of the temperature measurement location. The image forming apparatus according to claim 1, wherein a temperature measurement result by the non-contact temperature sensor is corrected.   The heat source control means determines a difference between a temperature measured by the contact temperature sensor and a temperature measured by the contact temperature sensor or a temperature measured by the non-contact temperature sensor in the vicinity of the temperature measurement location. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus determines that the contact-type temperature sensor or the non-contact-type temperature sensor is abnormal when the threshold value is exceeded.   The heat source control means determines that the non-contact temperature sensor is abnormal when the difference between the temperature measurement results of the plurality of areas measured by the non-contact temperature sensor exceeds a predetermined threshold. The image forming apparatus according to claim 1, wherein: At least two or more of the non-contact temperature sensors,
When the same area is measured by a plurality of the non-contact temperature sensors, and the difference in temperature measured by the non-contact temperature sensors exceeds the predetermined threshold, the heat source control means 5. The image forming apparatus according to claim 1, wherein the image forming apparatus determines that the non-contact temperature sensor is abnormal. The image forming apparatus according to claim 1.
A recovery means for recovering the abnormality of the non-contact temperature sensor;
The difference between the temperature measured by the contact temperature sensor and the temperature measured by the contact temperature sensor or the temperature measured by the non-contact temperature sensor in the vicinity of the temperature measurement location is determined. An image forming apparatus that operates when a threshold value is exceeded or when a difference between temperature measurement results of the plurality of areas measured by the non-contact temperature sensor exceeds a predetermined threshold value. The image forming apparatus according to claim 1.
A recovery means for recovering the abnormality of the non-contact temperature sensor;
The recovery means includes a film, a roller for winding the film, a roller for winding the film, and a driving means for driving the winding roller,
The film is disposed between the non-contact temperature sensor and the object to be heated,
The difference between the temperature measured by the contact temperature sensor and the temperature measured by the contact temperature sensor or the temperature measured by the non-contact temperature sensor in the vicinity of the temperature measurement location is determined. When the threshold value is exceeded, or when the difference between the temperature measurement results of the plurality of areas measured by the non-contact temperature sensor exceeds a predetermined threshold value, the roller to be wound is determined for a predetermined time. An image forming apparatus that is driven at a predetermined speed and winds up a predetermined amount of the film.   The image forming apparatus according to claim 7, wherein the film is a material that transmits infrared rays.   The image forming apparatus according to claim 6, wherein the recovery unit operates every predetermined period or every predetermined number of printed sheets.   8. The image forming apparatus according to claim 6, wherein the recovery unit operates when the power is turned on, when the unit of the image forming unit is cleaned, or when the calibration operation is executed.

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