JP2009180974A - Fixing device, image forming apparatus, control method and program for fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device of an image forming apparatus, capable of appropriately performing a temperature control. <P>SOLUTION: The fixing device includes: a first temperature detecting sensor (thermopile) for measuring the surface temperature of a fixing belt; and a second temperature detecting sensor (thermistor). In a condition that the measured temperature obtained by the second temperature detecting sensor is equal to or lower than a prescribed temperature (YES at S101), a heating source is controlled based on the measured temperature obtained by the second temperature detecting sensor (S103 and S105). In a condition that the measured temperature obtained by the second temperature detecting sensor is higher than a prescribed temperature (NO at S101), the heating source is controlled based on the measured temperature obtained by the first temperature detecting sensor (S109 and S105). Consequently, the device is prevented from carrying out control based on the measured value obtained by the first temperature detecting sensor under a dew-condensation state. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fixing device, an image forming apparatus, a fixing device control method, and a fixing device control program, and more particularly to a fixing device, an image forming apparatus, and a fixing device control method capable of controlling a favorable fixing temperature. And a fixing device control program.

  In an image forming apparatus (MFP (Multi Function Peripheral), facsimile apparatus, copying machine, printer, etc.), an image forming unit that forms a toner image on paper or an OHP sheet as a recording medium, and the toner image is fixed on the recording medium And a fixing device.

  The fixing device includes a fixing (heating) roller (or fixing belt) for heating the toner and a pressure roller for pressing the toner against the recording medium. The fixing roller is heated by a heating source such as a heater. The temperature of the heating source is adjusted so that the temperature for heating the toner is constant. A sensor that measures the temperature of the fixing roller is used to adjust the temperature.

  As such a sensor, it is considered to use a non-contact temperature sensor that detects the temperature by measuring the amount of infrared light.

  Patent Document 1 below discloses a technique for cleaning a filter provided between an object to be measured and a sensor with a cleaning member.

  Patent Document 2 discloses a fixing device that can change the position of the temperature detection unit into two positions, a temperature detection position and a cleanable position.

  Patent Document 3 discloses a fixing device including a cleaning member or a heater that removes water droplets attached to a filter in front of a temperature sensor.

  Patent Document 4 discloses a fixing device in which a temperature sensor is disposed in a section from a cleaning member of a heating roller to a front of a Nip (nip) portion. Based on the measurement result of the temperature sensor, the temperature control of the heating roller is performed.

  Patent Document 5 discloses a fixing device in which a lens or the like is provided between an object to be measured and a temperature sensor, and the temperature sensor is arranged at a position not affected by water vapor generated from the paper.

Patent Document 6 discloses an image forming apparatus that prohibits the running of a sheet under conditions where the temperature sensor is condensed.
JP 2002-340682 A JP 2004-184091 A JP 2005-227558 A JP 7-77888 A JP-A-7-77891 JP 2006-145968 A

  With the demand for high-quality images such as graphics applications, it is necessary to prevent scratches on the surface portion of a fixing roller (or fixing belt) that fixes a toner image. Therefore, the temperature detection sensor used in the fixing device is required to be able to detect the temperature without contact.

  As a temperature detection sensor that is arranged in a non-contact manner, a sensor that uses a thermistor element whose electric resistance varies with temperature and a sensor that measures the amount of infrared light are conventionally used.

  Sensors using thermistor elements that are arranged in a non-contact manner need to be corrected to estimate the temperature of the measurement object. Further, since it cannot follow a rapid temperature change, the temperature measurement near the fixing set temperature is inferior to the contact-type temperature detection sensor. Further, even if correction control for estimating temperature fluctuation due to a paper passing load is performed, it is inferior to a contact-type temperature detection sensor.

  A sensor (such as a thermopile) that measures temperature by measuring the amount of infrared light emitted from an object to be measured has good responsiveness and has detection performance equivalent to that of a contact-type temperature detection sensor.

  However, if there is an obstacle between the measurement object and the infrared light receiving unit, the amount of infrared light that can be received decreases, and the temperature is detected lower than actual. When the environment in which the image forming apparatus is installed changes drastically, it often becomes an obstacle due to condensation of the lens or filter between the measurement object and the infrared light receiving unit.

  When the image forming apparatus is in a standby state and the fixing device is kept at a high temperature, condensation hardly occurs. When the image forming apparatus is in a power-off state or in a sleep state and no power is supplied to the fixing device, condensation may occur due to a rapid environmental change.

  When the supply of power to the fixing device is started and heated while the condensation is left, a temperature lower than the actual temperature of the object to be measured is detected, so there is a high risk of trouble.

  Although it is possible to clean the filter part of a sensor window like the said patent document 1, the space for a cleaning member and a structural member is needed in this case.

  Further, as in Patent Document 4, it is conceivable to devise the arrangement position of the sensor and take measures to prevent dew condensation due to water vapor, but the problem is that it cannot cope with dew condensation due to fluctuations in the installation environment of the image forming apparatus. There is.

  The present invention has been made to solve the above problems, and provides a fixing device, an image forming apparatus, a fixing device control method, and a fixing device control program capable of performing appropriate temperature control. It is aimed.

  In order to achieve the above object, according to one aspect of the present invention, the fixing device includes a first temperature detection sensor that measures the temperature of an object to be measured heated by a heating source, and the temperature measured by the first temperature detection sensor. And a second temperature detection sensor for detecting the temperature of the measured object, wherein the first temperature detection sensor is a non-contact temperature for measuring the amount of infrared light emitted from the measured object. The second temperature detection sensor is a temperature sensor that uses a thermistor element, and the second temperature detection sensor has a measured temperature under a condition that the measured temperature of the second temperature detection sensor is equal to or lower than a predetermined temperature. And the first control means for controlling the heating source and the condition that the measured temperature of the second temperature detection sensor exceeds a predetermined temperature, the control of the heating source is performed based on the measured temperature of the first temperature detection sensor. Second control means for performing .

  Preferably, the measurement object is a heating roller or a fixing belt, and the second temperature detection sensor measures a temperature in the vicinity of the measurement position of the measurement object measured by the first temperature detection sensor.

  Preferably, the predetermined temperature is a preset temperature.

  According to another aspect of the present invention, an image forming apparatus includes any one of the fixing devices described above and an image forming unit that forms a toner image on a recording medium. The fixing device receives the toner image by the image forming unit. The toner image on the formed recording medium is fixed.

  According to still another aspect of the present invention, in the fixing device control method, the temperature is measured by the first temperature detection sensor for measuring the temperature of the object to be measured heated by the heating source, and the first temperature detection sensor. And a second temperature detection sensor for detecting a temperature of the measured object, wherein the first temperature detection sensor measures the amount of infrared light emitted from the measured object. It is a contact temperature sensor, and the second temperature detection sensor is a temperature sensor that uses a thermistor element, and when the measurement temperature of the second temperature detection sensor is equal to or lower than a predetermined temperature, the measurement temperature of the second temperature detection sensor In the first control step of controlling the heating source based on the above and the condition where the measured temperature of the second temperature detection sensor exceeds the predetermined temperature, the heating source is controlled based on the measured temperature of the first temperature detection sensor. The second control step for performing the control And a flop.

  According to still another aspect of the present invention, a fixing device control program measures a temperature with a first temperature detection sensor that measures the temperature of an object to be measured heated by a heating source, and the first temperature detection sensor. And a second temperature detection sensor for detecting the temperature of the measured object, wherein the first temperature detection sensor measures the amount of infrared light emitted from the measured object. It is a contact temperature sensor, and the second temperature detection sensor is a temperature sensor that uses a thermistor element, and when the measurement temperature of the second temperature detection sensor is equal to or lower than a predetermined temperature, the measurement temperature of the second temperature detection sensor In the first control step of controlling the heating source based on the above and the condition where the measured temperature of the second temperature detection sensor exceeds the predetermined temperature, the heating source is controlled based on the measured temperature of the first temperature detection sensor. Control To execute a control step to the computer.

  According to these inventions, it is possible to provide a fixing device, an image forming apparatus, a fixing device control method, and a fixing device control program capable of performing appropriate temperature control.

  Hereinafter, an electrophotographic image forming apparatus including a fixing device according to an embodiment of the present invention will be described with reference to the drawings.

  The fixing device includes a first temperature sensor that measures temperature by measuring the amount of infrared light, such as a thermopile, and a second temperature sensor that includes a thermistor element. The fixing device performs heater control based on the temperature detected by the second temperature sensor when the temperature detected by the second temperature sensor is equal to or lower than a preset temperature, and when the temperature exceeds the set temperature, Heater control is performed based on the temperature detected by the first temperature sensor. Thereby, the detected temperature of the object to be measured by the first temperature sensor in the dewed state is not adopted for the heater control. Thereby, the malfunction by temperature erroneous detection is prevented.

  That is, at a temperature at which the first temperature sensor that detects the temperature by measuring the amount of infrared light may condense, the heater control is not performed based on the detection result of the first temperature sensor, and the thermistor element is used. Heater control is performed based on the detection result of the second temperature sensor.

  With a relatively simple method of providing two different types of temperature detection sensors, the required temperature detection performance can be satisfied, the occurrence of high-temperature troubles can be suppressed, and a highly reliable fixing device can be obtained. .

  FIG. 1 is a diagram showing an overall configuration of a four-cycle image forming apparatus according to one embodiment of the present invention.

  Here, the image forming apparatus is the MFP 1. The MFP 1 is a multifunction device having functions such as a scanner, a copier, a printer, and a fax machine.

  The MFP 1 includes a plurality of keys 11a, an operation unit 11 that receives input of various instructions by the user's operation to the keys, data such as characters and numbers, a display that displays an instruction menu for the user and information about the acquired image. 12. A scanner unit 13 that optically reads a document to obtain image data; a printer unit 14 that prints an image on a recording sheet based on the image data; an ADF 17 that transports paper; and a paper feed that stores paper for image formation A tray 18 and a paper discharge tray 19 are provided.

  In addition, the machine is provided with a power supply unit 16 that converts a DC power supply voltage to be supplied to each element from an AC power supply, and a controller unit 23 that is equipped with arithmetic and storage functions for controlling the machine.

  The machine further includes a fixing device and an image forming unit that forms a toner image on a recording medium. The fixing device fixes the toner image on the recording medium on which the toner image is formed in the image forming unit.

  FIG. 2 is a perspective view illustrating a configuration of a belt-type fixing device provided inside the image forming apparatus. FIG. 3 is a diagram showing the installation position of the first temperature detection sensor 55, and FIG. 4 is a diagram showing the installation position of the second temperature detection sensor 56.

  Referring to the drawing, the fixing device is configured to apply a load between fixing roller 53 and pressure roller 54 to form fixing Nip. By passing the sheet on which the unfixed image is formed between the fixing belt 51 wound around the fixing roller 53 and the pressure roller 54, the toner is fixed on the sheet.

  The fixing belt 51 is wound around a heating roller 52 having a built-in heater lamp 57 (see FIGS. 3 and 4), whereby heat is supplied from the heater lamp, which is a heating source, to the fixing belt.

  In order to measure the surface temperature of the outer surface of the fixing belt 51, a first temperature detection sensor 55 and a second temperature detection sensor 56 are provided so as not to contact the fixing belt 51.

  The first temperature detection sensor 55 is a sensor that detects temperature by measuring the amount of infrared light, such as a thermopile, and a filter is provided between the light receiving element and the measurement object.

  The second temperature detection sensor 56 is a temperature detection sensor using a thermistor element whose electric resistance value varies with temperature.

  The measurement point (measurement position) of the fixing belt 51 measured by the first temperature detection sensor 55 and the measurement point of the fixing belt 51 measured by the second temperature detection sensor 56 are positioned in the vicinity. ing. This is so that both sensors can measure the position of the fixing belt 51 that is the object to be measured, at substantially the same temperature.

  On the basis of signals from the first temperature detection sensor 55 and the second temperature detection sensor 56, lighting control of the heater lamp 57 is performed, and the heating roller 52 and the fixing belt 51 are controlled to have predetermined temperatures. Is done.

  FIG. 5 is a block diagram illustrating a configuration of a temperature control device of a fixing device provided in the image forming apparatus.

  Referring to the figure, the temperature control device is composed of a CPU 60 that controls lighting of heater lamp 57 based on signals from first temperature detection sensor 55 and second temperature detection sensor 56.

  When the environment in which the image forming apparatus is installed changes rapidly, the image forming apparatus may condense. For example, dew condensation is likely to occur when the temperature is rapidly increased using heating in a place of low temperature and high humidity in winter. At that time, the filter of the first temperature detection sensor 55 mounted on the fixing device in the image forming apparatus also condenses. Due to condensation, a predetermined amount of infrared light emitted from the fixing belt 51 cannot be received. As a result, the first temperature detection sensor 55 erroneously detects that the temperature is lower than the actual temperature.

  Therefore, the image forming apparatus according to the present embodiment does not employ the measurement value of the first temperature detection sensor 55 for temperature control at the temperature at which condensation occurs.

  FIG. 6 is a flowchart showing the operation of the CPU 60 of FIG.

  Referring to the figure, in step S101, it is determined whether or not the measured value by second temperature detection sensor 56 is equal to or lower than a predetermined temperature (ie, equal to or lower than the temperature at which condensation occurs). If YES, the temperature measured by the second temperature sensor 56 is adopted in step S103 without adopting the temperature of the first temperature sensor 55.

  On the other hand, if “NO” in the step S101, the measured temperature of the first temperature sensor 55 is adopted in a step S109.

  In step S105, the temperature control of the heater lamp 57 is controlled based on the measured temperature employed.

  In step S107, it is determined whether to end the temperature control, and the processing from step S101 is repeated until YES is obtained.

  FIG. 7 is a diagram illustrating an output value of the temperature detection sensor when the fixing device is warmed up.

  In the figure, the horizontal axis indicates the elapsed time from the start of warm-up, and the vertical axis indicates the detected temperatures of the first temperature detection sensor 55 and the second temperature detection sensor 56, respectively.

  In the graph, the temperature detection value of the first temperature detection sensor 55 in the normal state is indicated by a solid line. This represents the temperature at the measurement position of the fixing belt 51 on the heating roller 52 which is a measurement object. In addition, the temperature detection value of the first temperature detection sensor 55 in the dew condensation state is indicated by a dotted line. If condensation occurs below a certain predetermined temperature, the first temperature detection sensor 55 cannot accurately measure the temperature of the fixing belt 51 on the heating roller 52 that is a measurement object.

  In the graph, the temperature detection value of the second temperature detection sensor 56 is indicated by a one-dot chain line. This is a value lower than the temperature at the measurement position of the fixing belt 51 on the heating roller 52 that is the measurement object. The temperature detection value of the second temperature detection sensor 56 is not affected by condensation.

  As described above, when the filter of the first temperature detection sensor 55 is not condensed, the output value of the first temperature detection sensor 55 is equal to the temperature of the measurement object, that is, the fixing belt 51. However, if the filter is condensed under the above conditions, water droplets on the filter block infrared light, and the first temperature detection sensor 55 erroneously assumes that the temperature is lower than the actual temperature. It will be detected.

  When the temperature around the first temperature detection sensor 55 is increased by turning on the heater lamp 57, the condensation of the filter is also eliminated, and the first temperature detection sensor 55 detects the temperature equal to the actual temperature of the object to be measured. Is possible.

  Since the second temperature detection sensor 56 is not a sensor that measures the amount of light, it is not affected by condensation. Since the second temperature detection sensor 56 is installed in a non-contact manner on the measurement object, the second temperature detection sensor 56 outputs a temperature lower than the actual temperature of the measurement object.

  In the present embodiment, these two types of temperature detection sensors are provided for the same measurement object to compensate for each other's drawbacks.

  That is, when the measured temperature of the second temperature detection sensor 56 that is not affected by condensation is equal to or lower than a predetermined temperature (“A” in the figure) (before time “C”), the first It is assumed that there is a possibility that the filter of the temperature detection sensor 55 is condensed. In this case, the lighting control of the heater lamp 57 is performed based on the detection result of the second temperature detection sensor 56.

  When the measured temperature of the second temperature detection sensor 56 exceeds a predetermined temperature (“A” in the figure) (after time “C”), the filter of the first temperature detection sensor 55 is condensed. Based on the detection result of the first temperature detection sensor 55, the lighting control of the heater lamp 57 is performed.

  In this way, the fixing belt 51 on the heating roller 52 that is the object to be measured can be heated to a temperature near “B”.

  It is assumed that the temperature “A” is about 100 ° C. at which condensation is unlikely to occur, and the temperature “B” is about 160 to 180 ° C. at the time of fixing.

  As in this embodiment, two types of temperature detection sensors with different characteristics are used, and the temperature detection sensor that measures the amount of infrared light by switching the temperature detection sensor used for the heater lamp lighting control according to the temperature. Can be performed. As a result, it is possible to obtain good temperature detection performance required for the fixing device.

  [Effects of the embodiment]

  According to the embodiment described above, two types of temperature detection sensors, that is, a temperature detection sensor that measures the amount of infrared light and a temperature detection sensor that uses an element whose electrical resistance value changes with temperature, are used in the fixing device. It becomes possible to take measures against condensation in the temperature detection sensor that measures the amount of external light.

  This makes it possible to control the temperature to a preset fixing temperature even when the environment changes, and a highly reliable fixing device can be obtained.

  [Others]

  The present invention can be implemented for image forming apparatuses such as MFPs, facsimile machines, and copiers regardless of color or black and white.

  Further, the processing in the above-described embodiment may be performed by software or by using a hardware circuit.

  In addition, a program for executing the processing in the above-described embodiment can be provided, and the program is recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, and a memory card and provided to the user. You may decide to do it. The program may be downloaded to the apparatus via a communication line such as the Internet.

  In addition, it should be thought that the said embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a diagram illustrating an overall configuration of a four-cycle image forming apparatus according to one embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration of a belt-type fixing device provided in the image forming apparatus. It is a figure which shows the installation position of the 1st temperature detection sensor 55. FIG. It is a figure which shows the installation position of the 2nd temperature detection sensor 56. FIG. FIG. 2 is a block diagram illustrating a configuration of a temperature control device of a fixing device provided in an image forming apparatus. It is a flowchart which shows operation | movement of CPU60 of FIG. It is a figure which shows the output value of the temperature detection sensor in the warm-up state of a fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 4 cycle color image forming apparatus 11 Operation part 11a Panel key 12 Display 13 Scanner part 14 Printer part 16 Power supply part 23 Controller part 51 Fixing belt 52 Heating roller 53 Fixing roller 54 Pressure roller 55 1st temperature detection sensor 56 2nd Temperature sensor 57 Heater lamp 60 CPU

Claims (6)

A first temperature detection sensor for measuring the temperature of an object to be measured heated by a heating source;
A fixing device comprising: a second temperature detection sensor for detecting a temperature of the object to be measured whose temperature is measured by the first temperature detection sensor;
The first temperature detection sensor is a non-contact temperature sensor that measures the amount of infrared light emitted from the object to be measured.
The second temperature detection sensor is a temperature sensor using a thermistor element,
A first control means for controlling the heating source based on the measured temperature of the second temperature detection sensor under a condition that the measured temperature of the second temperature detection sensor is equal to or lower than a predetermined temperature;
A second control means for controlling the heating source based on the measured temperature of the first temperature detection sensor under a condition that the measured temperature of the second temperature detection sensor exceeds the predetermined temperature; Fixing device. The object to be measured is a heating roller or a fixing belt,
The fixing device according to claim 1, wherein the second temperature detection sensor measures a temperature in the vicinity of a measurement position of the object to be measured which is measured by the first temperature detection sensor.   The fixing device according to claim 1, wherein the predetermined temperature is a preset temperature. A fixing device according to any one of claims 1 to 3,
Image forming means for forming a toner image on a recording medium,
The fixing device fixes an toner image on a recording medium on which a toner image is formed by the image forming unit. A first temperature detection sensor for measuring the temperature of an object to be measured heated by a heating source;
A fixing device control method comprising: a second temperature detection sensor that detects a temperature of the object to be measured, the temperature of which is measured by the first temperature detection sensor;
The first temperature detection sensor is a non-contact temperature sensor that measures the amount of infrared light emitted from the object to be measured.
The second temperature detection sensor is a temperature sensor using a thermistor element,
A first control step of controlling the heating source based on the measured temperature of the second temperature detection sensor under a condition that the measured temperature of the second temperature detection sensor is equal to or lower than a predetermined temperature;
A second control step of controlling the heating source based on the measured temperature of the first temperature detection sensor under a condition that the measured temperature of the second temperature detection sensor exceeds the predetermined temperature; Control method of fixing device. A first temperature detection sensor for measuring the temperature of an object to be measured heated by a heating source;
A control program for a fixing device, comprising: a second temperature detection sensor for detecting a temperature of the object to be measured whose temperature is measured by the first temperature detection sensor;
The first temperature detection sensor is a non-contact temperature sensor that measures the amount of infrared light emitted from the object to be measured.
The second temperature detection sensor is a temperature sensor using a thermistor element,
A first control step of controlling the heating source based on the measured temperature of the second temperature detection sensor under a condition that the measured temperature of the second temperature detection sensor is equal to or lower than a predetermined temperature;
When the measured temperature of the second temperature detection sensor exceeds the predetermined temperature, the computer executes a second control step for controlling the heating source based on the measured temperature of the first temperature detection sensor. A control program for the fixing device.

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