JP2005241544A - Control method for noncontact temperature detector, noncontact temperature detector, fixing device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively drive a pulsation pump to prevent dust or the like from being deposited, in an infrared reception part of a noncontact temperature sensor over a long period. <P>SOLUTION: In this fixing device provided with the noncontact temperature detecting sensor for detecting the temperature in a noncontact manner with a fixing roller heated by a heater, and the pulsation pump 90 for blowing air to increase the air pressure in an outlet part of the noncontact temperature detecting sensor to become higher than the atmospheric pressure, the pulsation pump 90 is controlled to increase the air flow rate in the outlet part of the noncontact temperature detecting sensor, when the fixing roller is operated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for controlling a temperature detection device that detects the temperature of a measurement object in a non-contact manner, a non-contact temperature detection device, a fixing device including the non-contact temperature detection device, and an image forming apparatus including the fixing device. .

  For example, image forming apparatuses such as copying machines, printers, and facsimiles are provided with a fixing device that fixes an unfixed toner image carried on a recording medium such as transfer paper by an electrophotographic method. This type of fixing device includes a heating roller that heats a recording medium that carries an unfixed toner image, and a pressure roller that is arranged so as to be pressed against the heating roller. A heat roller system is known in which a recording medium is nipped and conveyed and an unfixed toner image is fixed on the recording medium by heat and pressure. Recently, a fixing device of a type in which a fixing belt for conveying a recording medium is interposed between a heating roller and a pressure roller is also provided. In any of these methods, it is important to control the heating temperature in order to melt and soften the unfixed toner and to satisfactorily perform fixing by penetration into the recording medium.

  As a temperature detection method used for temperature management of the fixing device, a contact method and a non-contact method are known. As a contact-type temperature detection device, a thermistor is generally used as a temperature detection element. The thermistor is brought into contact with the surface of the heating roller, detects the temperature of the roller surface, and controls the temperature of the heating roller according to the detection result. However, in this system, it is essential to bring the thermistor into contact with the heating roller, and there is a possibility that the surface of the heating roller is damaged by the thermistor. If there is a scratch, the recorded image is soiled, and the heating roller or fixing unit must be replaced, resulting in an increase in cost.

  In addition, since the thermistor is usually attached to the fixing unit, the thermistor is also discarded when the fixing unit is replaced and discarded, which is not preferable in terms of cost and resource saving. It was. Furthermore, with such a contact type thermistor, the response speed is poor and it is difficult to perform precise control. In recent years, in particular, a fixing device that requires low power during standby and starts up at high speed only during use is required for energy saving. Therefore, there is a demand for detection means with good temperature response.

  On the other hand, in the non-contact type temperature detection device, the temperature is detected using a non-contact sensor such as a thermopile capable of detecting the amount of incident infrared rays emitted from the surface of the heating roller. The temperature is detected by a non-contact method to control the temperature of the heating roller.

  This non-contact sensor has not been commercialized because of the high cost of elements, control circuits, etc., and the fact that dirt over time adheres to the light receiving surface and the detection accuracy decreases. However, recently, a non-contact temperature detection type sensor has been requested again. This is because color printers / color copiers have rapidly spread, but the color machines have a silicon rubber layer for the rollers and belts to improve image quality, the surface is soft, and a fluorine-based release layer on the outermost surface. Provided. However, even if it is such, it will be easily damaged when the sliding state continues. Further, since silicon rubber is expensive, if it is damaged, the replacement cost is much higher than that of a metal roller. Also, from the viewpoint of environmental protection (resource saving), it is required to extend the life of the rollers and belts. For this reason, non-contact, high-accuracy detection means with good temperature responsiveness is required, and it can be said that thermopile is the optimum means as such detection means. Non-contact temperature sensors using a thermopile are described in Patent Documents 1 to 5, for example.

Further, in Patent Document 6, a shutter member that blocks infrared rays from the heating roller is provided, and when the temperature is not detected, the shutter is closed so that the thermopile is not exposed to the surrounding atmosphere. Has been proposed to prevent the thermopile from adhering to the thermopile. In Patent Document 7, a space is formed between the heating roller and the non-contact temperature sensor, and air is sent to the space by a blower fan or a pulsation pump. It has been proposed to form an air shielding layer in the space so that dust and dirt do not adhere to the light receiving part of the non-contact temperature sensor.
Japanese Patent Publication 1-17587 JP 7-77888 A JP-A-7-77891 JP-A-7-77892 JP 2002-350234 A JP 2003-162177 A JP 2003-307965 A

  FIG. 18 is a conceptual diagram showing an example of the configuration of a conventional fixing device provided with a non-contact temperature sensor. The non-contact temperature sensor 1 is configured such that the heating roller 2 and the pressure roller 4 rotate in contact with each other. Arranged in the upper case 31 and the lower case 41 and provided in the fixing device. A heater 3 as a heat source is provided in the heating roller 2, and a recording paper 11 on which a toner image 12 is transferred is passed through a nip portion between the heating roller 2 and the pressure roller 4. When the heating roller 2 is rotating clockwise as indicated by an arrow, the non-contact temperature sensor 1 is connected to the heating roller 2 upstream of the nip portion between the heating roller 2 and the pressure roller 4 when viewed from the rotation direction. It is arranged in a non-contact state with an interval of.

  The thermopile as the non-contact temperature sensor 1 is an infrared sensor that receives infrared rays and converts them into electrical signals, and is configured as shown in FIGS. 19 is a perspective view showing the appearance of the non-contact temperature sensor 1, and FIG. 20 is a cross-sectional view showing the internal structure. In these drawings, the thermopile 1 includes a can case 6 constituting a casing in which an opening window 5 is formed for an infrared light incident portion, and a window member 7 that covers the opening window 5 of the can case 6 and serves as an infrared transmission portion. And an electromotive force generated by a thermopile element 9 having an infrared absorption part 9a arranged inside the canister 6 and a thermocouple (not shown) arranged in the infrared absorption part 9a of the thermopile element 9 is output to the outside. And a seat member 10 that supports the thermopile element 9, the terminal 8, the thermocouple, and the like and serves as a bottom plate of the can case 6. The window member 7 is made of a material that can transmit at least infrared rays, and is made of, for example, a silicon wafer. The terminal 10 is electrically connected to control means (not shown).

  By the way, in addition to the above-mentioned thermopile, the non-contact temperature sensor that senses infrared rays and outputs a voltage includes a pyroelectric sensor, a thermopile, and the like. However, the thermopile is strongly dependent on the environmental temperature of the element itself. The characteristic is that the output changes as the temperature changes.

  When a thermopile is used, the temperature of the heating roller that is the object to be measured is obtained by the following equation.

Vout = A (Tb ^ 4-Ts ^ 4)
here,
A: Proportional constant Tb: Temperature of measurement object (K)
Ts: Thermopile temperature (K)
And ^ represents a power.

  For this reason, in a normal usage method, a temperature compensation thermistor is generally built in the thermopile, and the temperature of the thermopile is recognized by the output of the thermistor and correction is generally performed.

  Since the non-contact temperature sensor is affected by the ambient temperature in this way, it detects the ambient temperature and compensates for the temperature. However, the response of the thermistor is poor, so it cannot follow the ambient temperature when it suddenly changes. The temperature of the measurement object cannot be detected accurately. For this reason, when the ambient temperature changes abruptly, the control accuracy deteriorates. For example, when the power is turned on in the morning when the inside of the machine is cold, the temperature of the heating roller suddenly rises, so that the temperature around the thermopile in the vicinity also rises rapidly. Then, the thermistor output changes, and the ambient temperature change is detected and corrected. However, since the thermistor has poor response, the ambient temperature is detected low. As a result, it becomes impossible to grasp the accurate temperature of the measured object, and it becomes impossible to control to the set temperature. If temperature control to the set temperature becomes impossible in this way, a problem may occur in the fixing property.

  As a thermal problem of the thermopile element, the maximum operating temperature of the element is generally about 80 ° C. However, if it is brought close to the fixing roller, it may exceed 100 ° C. There is a risk of breaking. Therefore, it is necessary to take measures to shield from heat and to dissipate heat.

  On the other hand, in order to prevent the occurrence of an offset image, a method of improving surface releasability by applying a slight amount of silicon oil to the surface of the fixing roller or containing wax in the toner is used. The oil, wax and the like evaporate by the fixing heat and float in the apparatus. In addition, unfixed fine powder toner also floats in the apparatus. These suspended matters are then stirred by the cooling fan of the machine. In addition, paper dust is also generated during the paper transport process, and moisture in the paper evaporates due to heat during fixing and fills the machine.

  When these oils, wax, floating toner, paper dust, and water vapor adhere to the surface of the infrared light receiving window (filter, lens, etc.) of the thermopile (the amount of adhesion increases over time), the infrared rays are absorbed by the adhering matter and the incident infrared rays. A phenomenon occurs that the thermopile output decreases due to the decrease in the amount. As a result, the temperature is detected to be lower than the actual temperature, and the control temperature increases as a result of trying to return to normal, and an abnormal image may occur. For example, when the fixing temperature is 180 ° C. and the corresponding Vout is 2 V, the output drops to 1.8 V due to contamination. That is, the detection temperature is lowered by 0.2 V, and control is performed so as to return to 2 V. As a result, the fixing temperature is increased near 200 ° C. When this accelerates, the control temperature rises further, and the machine may detect a high temperature error and stop, or in the worst case, it may cause smoke.

ing. In the invention described in Patent Document 6, it is considered that when the temperature detection is performed, the shutter is opened and is not affected normally, but if the shutter is released, dust or dust in the ambient atmosphere is removed. May adhere to the thermopile.

  Further, although the blower fan proposed in Patent Document 7 can remove suspended matters from the vicinity of the element, the pressure loss is too large to be used for a general image forming apparatus. Although the pulsation pump is effective in terms of pressure loss, there is a drawback that it does not have a lifetime if it is kept running while the image forming apparatus is operating.

  The present invention has been made in view of the actual situation of the prior art, and its purpose is to effectively drive the pulsation pump so that dust or dirt adheres to the infrared light receiving part of the non-contact temperature sensor. It is to prevent.

  In order to achieve the above object, the first means includes a non-contact temperature detection sensor that detects a temperature in a non-contact manner with respect to a heated object heated by a heat source, and an air pressure at an outlet of the non-contact temperature detection sensor. In a control method of a non-contact temperature detection device comprising a pulsation pump that blows air so as to be higher than atmospheric pressure, the air pressure at the outlet of the non-contact temperature detection sensor is changed by changing the driving speed of the pulsation pump. It is characterized by controlling.

  The second means is characterized in that, in the first means, the driving speed of the pulsating pump is controlled so as to increase the flow rate of air at the outlet of the non-contact temperature detection sensor during operation of the heated object. To do.

  The third means is characterized in that, in the first or second means, the pulsation pump is controlled by DC solenoid driving.

  The fourth means is characterized in that, in the first or second means, the pulsation pump is controlled by AC solenoid driving.

  A fifth means is characterized in that, in the second means, the air flow rate is controlled by changing a pump driving frequency of the pulsating pump.

  The sixth means is characterized in that, in the second means, the air flow rate is controlled by changing a pump driving voltage of the pulsating pump.

  A seventh means is the first to sixth means, characterized in that the control is performed in accordance with an operating state of a machine which is a detection target of the non-contact temperature detection sensor.

  The eighth means includes a non-contact temperature detection sensor that detects the temperature in a non-contact manner with respect to the heated object heated by the heat source, and an air pressure at the outlet of the non-contact temperature detection sensor that is higher than the atmospheric pressure. A non-contact temperature detecting device comprising a pulsating pump for blowing air, characterized by comprising control means for changing the driving speed of the pulsating pump and controlling the air pressure at the outlet of the non-contact temperature detecting sensor. And

  A ninth means is the eighth means, wherein the control means controls the driving speed of the pulsating pump so as to increase the air flow rate at the outlet of the non-contact temperature detection sensor during operation of the heated object. It is characterized by that.

  A tenth means is the eighth or ninth means, wherein the control means controls the pulsating pump by DC solenoid drive.

  The eleventh means is characterized in that, in the eighth or ninth means, the control means controls the pulsating pump by AC solenoid drive.

  The twelfth means is characterized in that, in the eighth or ninth means, the control means controls the driving speed of the pulsating pump by changing the pump driving frequency of the pulsating pump.

  A thirteenth means is characterized in that, in the eighth or ninth means, the control means controls the driving speed of the pulsating pump by changing a pump driving voltage of the pulsating pump.

  The fourteenth means is any one of the eighth to thirteenth means, wherein the control means controls the driving speed of the pulsating pump according to the operating state of the machine that is the detection target of the non-contact temperature detection sensor. It is characterized by doing.

  The fifteenth means is characterized in that the fixing device includes the non-contact temperature detecting device according to any one of the eighth to fourteenth means.

  A sixteenth means is the fifteenth means characterized in that the fixing device comprises any one of a heat roller heating device, a belt heating device and an electromagnetic induction heating device.

  A seventeenth means is characterized in that the image forming apparatus includes the fixing device according to the fifteenth or sixteenth aspect.

  Since the pulsation pump is controlled so as to increase the air flow rate at the outlet of the non-contact temperature detection sensor during operation of the heated object, the pulsation pump is driven effectively, and the non-contact temperature sensor It is possible to prevent dust and dirt from adhering to the infrared light receiving part.

  Hereinafter, the best mode for carrying out the present invention will be described. Constituent elements identical to those of the above-described prior art are denoted by the same reference numerals, and descriptions of their configurations and functions are omitted unless particularly necessary.

  FIG. 15 is a diagram showing a schematic configuration of a printer as an image forming apparatus. The printer includes a paper feeding device 104, a registration roller pair 106, a photosensitive drum 108 as an image carrier, a transfer device 110, a fixing device 30, and the like.

  The paper feeding device 104 includes a paper feeding tray 114 that accommodates the recording paper 11 in a stacked state, a paper feeding roller 116 that sequentially feeds the recording paper 11 accommodated in the paper feeding tray 114 from the top, and a separating member. 117 and the like. The recording paper 11 fed from the paper feeding tray 114 by the paper feeding roller 116 is temporarily stopped by the registration roller pair 106, and after correcting the oblique deviation, the leading edge of the toner image formed on the photosensitive drum 108 and the recording are recorded. The paper 11 is fed from the registration roller pair 106 to the transfer position N at a timing when the preset position of the leading end portion in the transport direction of the paper 11 coincides.

  Around the photosensitive drum 108, in the rotation direction indicated by the arrows, a charging roller 118 as a charging unit, a mirror 120 constituting a part of an exposure device (not shown), and a developing device 122 including a developing roller 122a, A transfer device 110, a cleaning device 124 including a cleaning blade 124a, and the like are disposed. The exposure light 103 is irradiated and scanned between the charging roller 118 and the developing device 122 through the mirror 120 to the exposure unit 126 on the photosensitive drum 108.

  The image forming operation in the printer is performed in the same manner as before. That is, when the photosensitive drum 108 starts rotating, the surface of the photosensitive drum 108 is uniformly charged by the charging roller 118, and the exposure light 103 is irradiated and scanned on the exposure unit 126 based on the image information. An electrostatic latent image corresponding to is formed. The electrostatic latent image is moved to the developing device 122 by the rotation of the photosensitive drum 108 and is supplied with toner by the developing roller 122a to be visualized to form the toner image 12. The toner image 12 formed on the photosensitive drum 108 is transferred onto the recording paper 11 that has entered the transfer position N at a predetermined timing by applying a transfer bias by the transfer device 110. The recording paper 11 carrying the toner image 12 is conveyed to the fixing device 30 and fixed, and then discharged to a paper discharge tray (not shown).

  Residual toner remaining on the photosensitive drum 108 without being transferred at the transfer position N reaches the cleaning device 124 as the photosensitive drum 108 rotates, and is scraped off by the cleaning blade 124 a while passing through the cleaning device 124. It is. Thereafter, the residual potential on the photosensitive drum 108 is removed by a static eliminator (not shown) to prepare for the next image forming process.

  1 to 3 show the structure of the non-contact temperature sensor and the arrangement state with respect to the heating roller. FIG. 1 is a diagram for explaining an arrangement relationship between a heating roller and a non-contact temperature detecting device, FIG. 2 is an exploded perspective view of a sensor holder that holds a non-contact temperature sensor, and FIG. 3 is an arrangement of the non-contact temperature sensor with respect to the heating roller. It is a figure for demonstrating a relationship.

  In FIG. 1 thru | or 3, the code | symbol 21 is a sensor holder. The sensor holder 21 is integrally formed of a heat resistant resin and uses a material having low thermal conductivity so as to suppress the temperature rise of the sensor itself. The sensor holder 21 includes a barrel portion 22 that accommodates the non-contact temperature sensor 1 in the center and a cylindrical eaves portion 23, and the eaves portion 23 is opposed to the heating roller 2 of the fixing device 30 that is a detection target. ing. The non-contact temperature sensor 1 is fixed at a predetermined position on a control circuit board 52 on which a control circuit or the like is printed, and constitutes a sensor module unit 51. The non-contact temperature sensor 21 is inserted from the right side in the drawing into a hole (this hole communicates with the opening of the eaves portion 23) 24 formed in the body portion 22 of the sensor holder 21, and the control circuit board 52 is connected to the sensor holder. Positioning in the front-rear direction is made by abutting against the end face 25 of the body portion 22. The outer shape of the hole 24 and the can case 6 is fitted with no gap, so that the position of the outer shape portion is maintained. A rib protrusion having a hole 27 is formed at the lower end of the body portion 22. Reference numeral 26 denotes a sensor presser, and a protrusion 28 formed in the lower part is loosely fitted into the hole 27 of the body part 22, and the sensor presser 26 rotates in the arrow direction around the hole 27 and the protrusion 28 in the fitted state. . Reference numeral 53 denotes the entire sensor module. When assembling the sensor module 53, the sensor presser 26 is tilted clockwise, and after inserting the sensor module unit 51, the sensor presser 26 is rotated counterclockwise and fixed to the sensor holder 21 with the screw 29. 31 is a screw hole (tap hole). Reference numeral 30 denotes a rib for pressing the control circuit board 52 from the back to prevent the control circuit board 52 from coming off. In this embodiment, it is pressed at three positions. With such a minimum of two components, the sensor module can be easily positioned with high accuracy, and can be removed and assembled with a single screw during sensor assembly or replacement, improving service maintenance.

  In FIG. 3, the sensor module 53 detects the temperature from above the heating roller 2 as indicated by symbol A, and detects the temperature from the side of the heating roller 2 as indicated by symbol B. The case where it arrange | positions is considered. The floating substance 50 floats around the entire periphery of the fixing device 30. FIGS. 4 to 5 show the results of measuring the contamination of the light receiving surface in such an attached state. 4 is a diagram showing dirt on the light receiving surface when the sensor module is arranged above the heating roller, and FIG. 5 is a diagram showing dirt on the light receiving surface when the sensor module is arranged on the side of the heating roller. These figures are reduced micrographs (100 times) when installed on an actual machine and passed 400,000 sheets. The black dots in FIG. 5 are toner, wax, etc., and the size of the large particles is several microns. FIG. 4 shows these growing and bonded together. As is clear from this, the suspended matter 50 flows upward. As a result, it was proved that the installation in the state of FIG. However, there are cases where it is absolutely necessary to detect from above or obliquely upward due to machine design restrictions. In general, as shown in FIG. 1 and FIG. In order to proceed, there is often no sufficient installation space in the lateral direction on the recording paper inlet side and outlet side. In the downward direction, when printing is performed, when the recording paper is conveyed, temperature detection is interrupted, and dirt may further fall from the top. Therefore, it is convenient if it can be detected from above.

  In the present invention, dirt is actively prevented so that it can be detected from above. As shown in FIG. 6 and FIG. The sensor holder 21 is not contaminated. FIG. 6 is a diagram illustrating a case where air is introduced from the eaves portion of the sensor holder, and FIG. 7 is a diagram illustrating a case where air is introduced from the trunk portion of the sensor holder. In FIG. 6, an opening is formed near the trunk portion 22 of the eave portion 23 of the sensor holder 21 so as to communicate with the hollow portion of the eave portion 23, and a joint member 71 is provided therein, and the joint member 71 is provided on the pump side. One end of the tube 70 to which the other end is connected is connected. Air of pressure P is supplied from the outside, and the air travels in the direction of the arrow. Since the outlet pressure P1 is higher than the ambient pressure (atmospheric pressure) P0, dirt does not enter inside.

  FIG. 7 shows a configuration in which the air flow is more smoothly directed outward. That is, air is applied toward the can case 6 of the non-contact temperature sensor 1. In this method, a gap 72 is provided in the body portion 22 of the sensor holder 21 so as to face the outer peripheral portion of the can case 6 of the non-contact temperature sensor 1, an opening is formed so as to communicate with the gap, and a joint is formed there. One end of the tube 70 is connected via the member 71. Thus, after the air from the tube 70 has flowed once along the outer periphery, it can be blown out toward the outlet. In this method, there is no stagnation or stagnation of air as shown by an arrow 73 in FIG. 6, so that it is more effective to prevent the light receiving window 5 of the contact temperature sensor 1 from being stained. If fresh air is flowed from the outside, these airs have a cooling effect on the contact temperature sensor 1 itself, and are effective in preventing temperature rise. It is effective to increase the pressure (flow rate) when the sensor temperature exceeds a certain value.

  8 to 10 show an example of an air supply device for the tube 70. FIG. 8 is a cross-sectional view showing a case where the air supply device is configured by a blower fan, FIG. 9 is a front view of the blower fan of FIG. 8, and FIG. 10 is a cross-sectional view showing a case where the air supply device is configured by a reciprocating pump.

  8 and 9, the blower fan 75 is detachably attached to the casing 81 with a plurality of screws 82. The casing 81 is detachably attached to the exterior cover 83 of the printer with a plurality of screws 84. The other end of the tube 70 is connected to the tip of the casing 81. The fan pressure P2 of the blower fan 75 shown in FIG. 8 causes a pressure loss because the opening diameter of the inlet portion 76 of the tube 70 is small, and the sensor inlet portion pressure P hardly occurs. That is, there is no antifouling effect.

  On the other hand, FIG. 10 uses a pulsation pump 90 which is an air pump instead of the blower fan 75. The pulsating pump 90 includes a telescopic diaphragm 77 having a bottomed cylindrical shape, a holding portion 91 that holds an open end of the diaphragm 77, and an armature 79 provided at the bottom of the diaphragm 77. The other end of the tube 70 is connected to the holding portion 91, and a valve 78 a for taking outside air into the diaphragm 77 and a valve 78 b for discharging the air in the diaphragm 77 to the non-contact temperature sensor 1 are provided. . Air enters and exits in the direction of the arrow. When experimented with this method, the air pressure was as shown in FIG. 12, which is a graph of the air pressure by the air pump, and it was found that the pressure P was sufficiently supplied to the inside of the sensor. In FIG. 12, t1 is one reciprocation time of the pulsation pump 90, and there are a discharge process and a suction process during one reciprocation, but FIG. 12 shows only the discharge process. P on the vertical axis is the pressure. Thereby, if the pulsating flow pump 90 was used, it has confirmed that the aim of this invention could be achieved. There are AC driving and DC driving as the driving means of the pump.

  As a driving means for the pulsation pump, when AC 79 is used as an electromagnet in AC driving in FIG. 10 and an AC voltage as shown in FIG. 11A is applied to a solenoid (not shown), the S pole, N at the same cycle as the AC frequency. A pole is generated, the armature 79 is attracted and repelled by the solenoid, the diaphragm 77 reciprocates in the direction of the arrow, and air is supplied. If the frequency is changed, the pump pressure (flow rate) can be changed. This energization control to the solenoid is performed from a control device (not shown). This control device corresponds to the control means in the claims. This method has a simple configuration, for example, the same configuration as an air pump used for a tropical fish tank. In FIG. 11A, the vertical axis represents voltage (V) and the horizontal axis represents time (sec). The alternating current has a + direction upward and a − direction downward with respect to the center.

  Moreover, as a drive means of the pulsation pump 90, direct current drive is also possible. In DC drive, the armature 79 is made of a magnetic material such as pure iron, and when a DC voltage as shown in FIG. 11B is applied to a solenoid (not shown), the diaphragm 77 is pulled in the right direction in FIG. The diaphragm 77 moves in the opposite direction (left direction) by a spring (not shown) and discharges air. The solenoid force may be used when discharging in reverse. In FIG. 11B, the vertical axis represents voltage (V), the horizontal axis represents time (sec), the intersection with the X axis is 0 V, and a positive voltage is given above. In the case of alternating current, t1 is 20 ms when the frequency is 50 Hz. In the case of direct current, t1 varies depending on the drive pulse waveform and the return spring force of the diaphragm 77. However, if one reciprocation time is set to 20 ms, the cycle is the same as the alternating current of 50 Hz. In this way, to change the flow rate by direct current drive, it can be easily controlled by changing the applied pulse frequency or changing the applied voltage. The energization control and frequency control to the solenoid are performed from a control device (not shown). This control device corresponds to the control means in the claims.

  FIG. 13 is a graph showing the pressure change. 13A shows a case where the frequency of FIG. 12 is doubled, and FIG. 13B shows a case where the driving voltage is lowered to weaken the pressure. In the case of direct current drive, the weakening as shown in (B) can be performed by changing the voltage and extending the time of one reciprocation (t1). In the case of alternating current drive, it is necessary to consider a safety device as a safety measure because of the high voltage, but in the case of direct current, the voltage is low and there is no concern about this.

  In this way, a sufficient pressure can be obtained by using the pulsation pump 90, and even if it is mounted on top, dirt does not enter the opening window 5 of the non-contact temperature sensor 1. FIG. 14 shows a reduced photomicrograph (100 times) when 400,000 sheets are passed when the sensor module 53 is mounted on the top (position A in FIG. 3) in the configuration of FIG. There is almost no dirt, which proved effective in any installation position. In addition, the pulsation pump 90 is driven, but since the dirt fluctuates during printing, the pressure can be increased by the method described above, and the pressure can be decreased during standby other than printing, thereby extending the life of the pump, Long-term reliability can be secured. Note that printing and standby can be determined by a CPU that controls the entire printer.

  In the embodiment described above, the temperature detection has been described with the fixing device using the heat roller, but the present invention is not limited to the heat roller (fixing roller). In the future, color printers, color copiers, etc., which will grow rapidly, will use soft rollers or belts (metal roller or belt surface) instead of heat rollers (metal roller surface coated with Teflon (registered trademark)) in order to obtain high-quality images. The silicon rubber layer is used. In this case, the surface of the contact sensor is easily damaged due to the rubber surface. Therefore, non-contact sensors such as the present invention will become increasingly necessary in the future.

  FIG. 16 shows a belt-fixing type fixing device that uses a belt instead of a heat roller, and a belt wound between a heating roller 201 heated by a heater 205 and a tension roller 202 as a fixing rotating body. When the fixing belt 203 as a member is used, the non-contact temperature sensor 1 may detect the infrared rays from the identification receiving belt 203 with the fixing belt 203 as a measurement target. This can have the same effect as a heat roller.

  Furthermore, as mentioned at the beginning, the induction heating fixing method is an effective energy saving means for reducing the power consumption of fixing by shortening the rise time and increasing the thermal efficiency. FIG. 17 is a diagram showing an example in which the present invention is applied to an induction heating fixing device. In the figure, 301 is a heating roller, 302 is a fixing roller, 303 is a heating belt, 304 is a pressure roller, and 306 is an induction heating device. The induction heating device 306 includes an exciting coil 307, a coil guide plate 308, an exciting coil core 309, and a support member 310. The induction heating device 306 generates heat by the same operation as the conventional induction heating device and heats the belt 303. Then, by causing the belt 303 to face the non-contact temperature sensor 1 and detecting the infrared rays from the belt 303 with the non-contact temperature sensor 1, the same effect as when detecting the temperature of the heat roller in a non-contact manner can be obtained. Can have.

  In the embodiment described above, the temperature detection of the fixing device of the image forming apparatus has been described. However, the non-contact temperature detection device of the present invention can be applied to a temperature detection device in an easily contaminated environment such as an electronic cooker or an air conditioner. The reliability of temperature detection can be improved, and countermeasures against temperature rise can be appropriately handled.

It is a figure for demonstrating the arrangement | positioning relationship between the heating roller of the fixing device which concerns on this embodiment, and a non-contact temperature detection apparatus. It is a disassembled perspective view of the sensor holder holding the non-contact temperature sensor concerning this embodiment. It is a figure for demonstrating the arrangement | positioning relationship of the non-contact temperature sensor with respect to a heating roller. It is a figure which shows the stain | pollution | contamination of a light-receiving surface at the time of arrange | positioning a sensor module above a heating roller. It is a figure which shows the stain | pollution | contamination of a light-receiving surface at the time of arrange | positioning a sensor module to the side of a heating roller. It is a figure which shows the structure which introduces air from the eaves part of a sensor holder. It is a figure which shows the structure which introduces air from the trunk | drum of a sensor holder. It is sectional drawing which shows the principal part of the air supply apparatus which uses a ventilation fan. It is a front view of the ventilation fan of FIG. It is sectional drawing of the air supply apparatus which uses a pulsation pump. It is a wave form diagram which shows the waveform of the power supply which drives a pulsation pump, (a) shows the case of AC power supply, (b) shows the case of DC power supply. It is a wave form diagram which shows the air pressure by a pulsation pump. It is a wave form diagram which shows the pressure change by a pulsation pump. It is a figure which shows the stain | pollution | contamination of the light-receiving surface of a sensor module in the case of a pulsation pump. 1 is a schematic configuration diagram of an image forming apparatus including a fixing device according to the present invention. 1 is a schematic configuration diagram of a belt fixing type fixing device. FIG. 2 is a schematic configuration diagram of an induction overheating type fixing device. It is a conceptual diagram which shows an example of a structure of the conventional fixing device provided with the non-contact temperature detection sensor. It is a perspective view which shows the external appearance of the non-contact temperature sensor of FIG. It is sectional drawing which shows the internal structure of the non-contact temperature sensor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Non-contact temperature sensor 2 Heating roller 3 Heater 4 Pressure roller 5 Opening window 6 Can case 7 Window member 9 Thermopile element 11 Recording paper 12 Toner image 21 Sensor holder 22 Trunk part 23 Eaves part 30 Fixing device 70 Tube 72 Gap 75 Air blow Fan 90 Pulsating pump 108 Photosensitive drum 110 Transfer device 122 Developing device 201, 301 Heating roller 203 Fixing belt 302 Fixing roller 303 Heating belt 306 Induction heating device

Claims (17)

A non-contact temperature detection sensor for detecting the temperature in a non-contact manner with respect to the heated object heated by the heat source, and a pulsation pump for blowing air so that the air pressure at the outlet of the non-contact temperature detection sensor is higher than the atmospheric pressure. In the control method of the non-contact temperature detection device comprising:
A control method for a non-contact temperature detection device, wherein the air pressure at the outlet of the non-contact temperature detection sensor is controlled by changing a driving speed of the pulsation pump.   2. The non-contact temperature detecting device according to claim 1, wherein the driving speed of the pulsating pump is controlled so as to increase an air flow rate at an outlet of the non-contact temperature detecting sensor during operation of the heated body. Control method.   The non-contact temperature detecting device control method according to claim 1, wherein the pulsating pump is controlled by DC solenoid driving.   The method for controlling a non-contact temperature detecting device according to claim 1, wherein the pulsating pump is controlled by AC solenoid driving.   3. The method of controlling a non-contact temperature detecting device according to claim 2, wherein the air flow rate is controlled by changing a pump driving frequency of the pulsating pump.   3. The method of controlling a non-contact temperature detecting device according to claim 2, wherein the air flow rate is controlled by changing a pump driving voltage of the pulsating pump.   The method of controlling a non-contact temperature detection apparatus according to claim 1, wherein the control is performed according to an operating state of a machine that is a detection target of the non-contact temperature detection sensor. . A non-contact temperature detection sensor for detecting the temperature in a non-contact manner with respect to the heated object heated by the heat source, and a pulsation pump for blowing air so that the air pressure at the outlet of the non-contact temperature detection sensor is higher than the atmospheric pressure. In the non-contact temperature detection device comprising
A non-contact temperature detecting device comprising a control means for changing the driving speed of the pulsating pump and controlling the air pressure at the outlet of the non-contact temperature detecting sensor.   9. The non-control device according to claim 8, wherein the control means controls the driving speed of the pulsating pump so as to increase the flow rate of air at the outlet of the non-contact temperature detection sensor during operation of the heated object. Contact temperature detector.   The non-contact temperature detecting apparatus according to claim 8 or 9, wherein the control means controls the pulsating pump by direct current solenoid driving.   The method for controlling a non-contact temperature detecting apparatus according to claim 8 or 9, wherein the control means controls the pulsating pump by AC solenoid driving.   The non-contact temperature detecting device according to claim 8 or 9, wherein the control means controls a driving speed of the pulsating pump by changing a pump driving frequency of the pulsating pump.   The non-contact temperature detecting device according to claim 8 or 9, wherein the control means controls a driving speed of the pulsating pump by changing a pump driving voltage of the pulsating pump.   14. The control unit according to claim 8, wherein the control unit controls the driving speed of the pulsating pump in accordance with an operating state of a machine that is a detection target of the non-contact temperature detection sensor. The non-contact temperature detection apparatus described.   15. A fixing device comprising the non-contact temperature detecting device according to claim 8.   The fixing device according to claim 15, wherein the fixing device includes any one of a heat roller heating device, a belt heating device, and an electromagnetic induction heating device.   An image forming apparatus comprising the fixing device according to claim 15.

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