JP2006184071A - Temperature detector and temperature controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the accuracy of temperature control on a photoconductor within a definite range and to prevent an adverse effect caused by a soiled lens of a thermopile temperature sensor. <P>SOLUTION: This temperature detector for detecting the temperature of a heated body heated by a heating means, is equipped with a first non-contact temperature detection means, a second non-contact temperature detection means, and an air-flow generation means for generating an air flow. The first non-contact temperature detection means is provided for the heated body in a non-contacting manner to detect the temperature of the heated body corresponding to the amount of infrared radiation radiated from the heated body. The second non-contact temperature detection means is provided for the heated body in a non-contacting manner to directly detect the amount of convective heat or that of infrared radiation from the heated body, thereby detecting the temperature of the heated body. When performing temperature detection by using first or second non-contact temperature sensor, detection is performed after stopping or inhibiting the generation means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for detecting / controlling the temperature of an object to be heated that is heated by a heating unit. For example, the present invention relates to a temperature control apparatus for a photoreceptor in an image forming apparatus and a temperature control apparatus for an image fixing apparatus.

  2. Description of the Related Art Conventionally, image forming apparatuses using electrophotographic technology include ones that charge the surface of a photoconductor using corona discharge of the photoconductor, and form an image through a process of exposure and development. Widely used as facsimiles, printers, etc.

  However, in these electrophotographic apparatuses, it is known that ozone products adhere to the surface of the photoconductor, and an image flow (a phenomenon in which an image is blurred) occurs particularly at high humidity. In the case of a photoconductor that is relatively easy to wear, such as an organic photoconductor (OPC), ozone products and the like formed on the surface can be easily removed by polishing means. However, if the polishing effect is increased, the photoconductor As a result, the function is lowered and the life is shortened. On the other hand, there are some which are very hard like an amorphous silicon photoconductor and the ozone product formed on the surface is difficult to be removed by abrasion.

  Therefore, a photoconductor heater is disposed in or near the photoconductor to control the temperature of the surface of the photoconductor to approximately 35 ° C. to 45 ° C. The temperature control of the photoconductor is performed for various purposes, and the main purpose is to prevent and remove image flow that occurs at high humidity. This is because ozone generated in the corona charger chemically alters the surface of the photoconductor to form hydrophilic groups and the like, making it easy to absorb moisture, which causes a fatal phenomenon as electrophotography such as lateral flow of surface potential. Therefore, the temperature control is performed to remove moisture. In addition, since substances such as NOx produced by ozone adhere to the surface of the photoreceptor and absorb moisture in the same manner, the temperature is similarly controlled to remove moisture.

  In order to control these temperatures, conventionally, a heater as a heating source, a thermistor as a temperature detecting means, and a heater driver for controlling the heating source by an output from the temperature detecting means are arranged inside the photosensitive member as shown in FIG. A method of directly detecting the temperature of the heating source using a thermistor disposed inside the source (Canon IR6000) is employed. Although the heating source is disposed inside the photosensitive member as shown in FIG. 3, the thermistor as temperature detecting means is used. Is a method of controlling the temperature by controlling the heating source with a heater driver arranged outside the photoconductor by detecting the convection heat on the surface of the photoconductor (Canon). Company CLC1000). This latter method has an advantage that the heating source can be controlled by directly detecting the temperature of the photosensitive member surface by detecting the temperature of the surface of the photosensitive member directly to detect a change in the surface temperature of the photosensitive member.

  However, this method uses a thermistor that detects convection heat in a non-contact manner with the surface of the photoconductor to prevent the thermistor, which is a temperature detection means, from scratching the surface of the photoconductor. In addition, it is difficult to increase the accuracy, and the detection value is also affected by the distance from the surface of the photoconductor, so that it is difficult to increase the accuracy. In addition, the response speed of temperature detection becomes longer due to the heat capacity of the thermistor element itself, which causes a problem of increased temperature ripple.

  Therefore, recently, it has been studied to use an infrared detection type temperature detection means for detecting the temperature by detecting the amount of infrared rays emitted from the surface of the photoreceptor. As a typical infrared detection type sensor, there is a thermopile type temperature sensor shown in FIG. This sensor is a temperature sensor that uses a thermopile element in which two different kinds of metals or semiconductors are connected in series. The cold junction is placed on a heat sink with a large heat capacity as a reference, and the hot junction has a small heat capacity. After being fixed to the member, it is covered with an infrared absorbing member.

  Infrared light emitted from the surface of the photoconductor is collected through the lens, or only a specific infrared wavelength is absorbed by the infrared absorbing member through the filter instead of the lens, and the thermopile element corresponds to the temperature difference between the cold junction and the hot junction The signal output (a) is output. A thermistor element is arranged at the cold junction, and the thermistor detects the absolute temperature of the cold junction and outputs a signal (b) corresponding to the temperature, and (a) and (b) are input to the arithmetic circuit. Thus, a signal output (c) is obtained as the absolute temperature of the photosensitive member surface.

  The thermopile temperature sensor detects the convection heat because the thermopile element and the thermistor are combined with the arithmetic circuit in the process of manufacturing and adjusted so that the accuracy is obtained according to the actually used detection temperature. Compared with a non-contact thermistor or a thermistor-type non-contact temperature sensor (for example, Ishizuka Electronics NC sensor), the temperature detection accuracy can be increased. If the temperature detection accuracy is high, avoidance of image flow caused by lowering the surface temperature of the photoconductor and increasing latitude for failure due to toner melting / solidification caused by higher photoconductor surface temperature, The stability of the body surface is expected to improve image stability. Further, since the temperature detection is performed in the thermopile portion formed very finely, there is an advantage that the response speed is faster than that of the non-contact thermistor.

JP 2003-028721 A JP 2000-259033 A

  However, when a thermopile temperature sensor is used, necessary and sufficient maintenance including lens cleaning is not performed, and if the lens becomes dirty with paper dust or toner, the amount of infrared rays transmitted through the lens is reduced, and the detection temperature is lowered. It will shift. If temperature control is performed with the detected temperature deviating to the lower side, the actual temperature of the photoconductor increases, and the toner melts and hardens on the developing sleeve in contact with the photoconductor, or the potential fluctuates due to fluctuations in the photoconductor surface temperature. Therefore, there is a problem that the stability of the image is deteriorated.

  As a method for improving the detection accuracy when using a thermopile type temperature sensor, there is a method disclosed in Patent Document 1, which is based on a plurality of thermistors used in addition to the thermopile element, and a reference temperature (absolute temperature). ) Is improved and has no effect on the problem of temperature deviation due to lens contamination.

  In the invention shown in Patent Document 2, a contact thermistor is provided for determining a detected temperature deviation due to dirt on the lens. A contact / separation mechanism is provided on the contact thermistor, and the contact thermistor is separated during normal operation to detect the detected temperature deviation. However, since a contact / separation mechanism is required, there is a problem in the size and cost of the apparatus.

  Further, (Fuji X DCP2425) uses a thermopile temperature sensor for temperature control of the fixing device, and a cleaning member for cleaning the lens and an actuator for driving the cleaning member are prepared. Although this method is a countermeasure against lens contamination, the space and cost required for these mechanisms are problematic.

  As an invention for solving these problems, a thermopile type temperature sensor that detects infrared rays radiated from a photoconductor through a lens or a filter, and a thermistor arranged in a noncontact manner to detect convection heat from the photoconductor, Based on the detection information, the detection temperature of the thermopile temperature sensor is corrected, the degree of contamination of the thermopile temperature sensor is warned, and heating by the heating source is stopped based on the detection information of the thermistor arranged in a non-contact manner. Thus, proposals have been made to maintain the accuracy of temperature control of the photosensitive member within a certain range and to prevent the harmful effects caused by contamination of the thermopile temperature sensor lens.

  However, since the non-contact thermistor is strongly affected by the ambient air flow, there is a problem that the temperature cannot be measured accurately in a portion where the air flow is present.

  Accordingly, the present invention provides a means for stopping the flow of air when performing temperature detection with a non-contact thermistor, thereby correcting the detection temperature of the thermopile type temperature sensor based on higher temperature detection accuracy, and the thermopile type temperature sensor. The temperature control accuracy of the photoconductor is maintained within a certain range by stopping the heating by the heating source based on the detection information of the thermistor arranged in a non-contact manner. The object is to prevent harmful effects caused by contamination of the sensor lens.

In order to achieve the above object, the present invention provides a temperature detecting device for detecting the temperature of a heated object heated by a heating means.
A first non-contact temperature detecting means which is provided in a non-contact manner on the heated body and detects the temperature of the heated body according to the amount of infrared rays emitted from the heated body;
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow generating means for generating an air flow,
When performing temperature detection by the first or second non-contact temperature sensor, the detection is performed after the airflow generating means is stopped or suppressed.

Further, the present invention is a temperature control device that detects the temperature of the heated object heated by the heating means and controls the temperature of the heated object by controlling the heating means.
1st non-contact temperature detection which is provided in the said to-be-heated body in non-contact, condenses the infrared rays radiated | emitted from the to-be-heated body through a condensing means, and detects the temperature of the said to-be-heated body according to the amount of infrared rays Means,
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow generating means for generating an air flow,
When performing temperature detection with the first or second non-contact temperature sensor, the detection is performed after stopping or suppressing the air flow generating means,
First temperature control means for controlling the temperature of the object to be heated by controlling the heating means based on detection information from the first temperature detection means;
When the detection information of the second non-contact temperature detecting means exceeds a predetermined range, heating of the heated object by the heating means is stopped.

  According to the present invention, the first temperature detecting means represented by a thermopile type temperature sensor that detects infrared rays radiated from the photosensitive member through a lens or a filter, and the convection heat and infrared rays from the photosensitive member are directly detected and contactless. There is a second temperature detection means represented by the arranged non-contact thermistor and a means for controlling the air flow around the temperature detection means. When temperature detection is performed, the air flow is stopped and the influence of the air flow is eliminated. The temperature detection accuracy is improved by performing temperature detection above, and the detected temperature of the first temperature detection means is corrected based on the second temperature detection information, or the degree of contamination of the first temperature detection means is warned. Or by stopping the heating by the heating source based on the detection information from the second temperature detection means, the temperature control accuracy of the heated object is maintained within a certain range, and the lens of the first temperature detection means F It is possible to prevent the adverse effects generated by filter member from being contaminated.

  Hereinafter, a temperature detection device according to the present invention will be described in detail with reference to the drawings.

<Embodiment>
Embodiments of the present invention will be described with reference to the accompanying drawings.

  First, an image forming apparatus 1 as an example that suitably shows an image forming apparatus using a temperature detection apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a schematic configuration of the image forming apparatus 1.

  The image forming apparatus 1 includes a document (not shown) that passes through a predetermined position of the document glass 3 by an automatic document feeder 2 and a document (not shown) that is sequentially fed and placed on the document glass 3. The document illumination lamp 4 configured by, for example, a halogen lamp is exposed or exposed and scanned.

  The document illumination lamp 4 provided in the image forming apparatus 1 includes the scanning mirrors 5, 6, and 7 for reflecting and changing the trajectory of the reflected light image obtained by exposure or exposure scanning, and the image forming apparatus 1. Is held in an optical scanning unit that is freely supported in the normal direction and horizontal direction of the paper surface, and the optical scanning unit repeats reciprocating motion in the normal direction of the paper surface and horizontal direction of the paper surface. Is exposed and scanned by the original illumination lamp 4, so that the obtained reflected light image is converted from analog data to digital data after the trajectory is changed by the scanning mirrors 5, 6, and 7. To the CCD unit 8.

  The CCD unit 8 provided in the image forming apparatus 1 includes, for example, an imaging element 9 configured by a known CCD or the like, an imaging lens 10 that forms the obtained reflected light image on the imaging element 9, and an imaging unit, for example. A CCD driver 11 for driving the element 9, and after converting the output signal output from the imaging element 9 according to the obtained reflected light image into corresponding digital data, for example, 8-bit digital data, The data is input to the controller unit 12 provided in the image forming apparatus 1.

  A reflected light image obtained by exposure scanning of the document illumination lamp 4 provided in the image forming apparatus 1 is formed on the image sensor 9 in the CCD unit 8, but the light distribution in the longitudinal direction of the document illumination lamp 4. In addition, a white plate 62 is provided to eliminate the influence of sensitivity unevenness and the like of the image sensor 9. The white plate 62 is painted white on the surface read by the document illumination lamp 4, and the reflected light image of the white plate 62 is formed on the image sensor 9, and the digital data at this time is sent to the image forming apparatus 1. The data is input to the controller unit 12 provided.

  Further, the image forming apparatus 1 includes a photosensitive drum 14 as a cylindrical or columnar latent image carrier, a pre-exposure lamp 15 for removing the outer peripheral surface of the photosensitive drum 14 to prepare for the next image formation, and a photosensitive drum. The outer peripheral surface of the photosensitive drum 14 is charged with a predetermined potential distribution by corona charging to prepare for latent image formation, and the photosensitive drum 14 is charged with the primary charger 16 and is configured by, for example, a known semiconductor laser. A laser unit having two light sources that exposes the outer peripheral surface based on digital data input from the controller unit 12 and thereby forms an electrostatic latent image corresponding to the given image data on the outer peripheral surface of the photosensitive drum 14. 17 and a developing device as developing means for developing the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 14 into a visible image (toner image) by applying a developer (hereinafter referred to as toner). And a 8.

  Around the photosensitive drum 14 provided in the image forming apparatus 1, there is a pre-exposure lamp 15, a primary charger 16, a developing unit 18, and a high-pressure image on the outer peripheral surface of the photosensitive drum 14 before transfer. A transfer charger 20 for transferring a visible image onto the recording paper P by, for example, a known corona discharge, and the recording paper P after the transfer process from the outer peripheral surface of the photosensitive drum 14. A separation charger 21 for separation and a cleaner 22 for removing and collecting the developer remaining on the outer peripheral surface of the photosensitive drum 14 after the transfer is completed are provided.

  That is, the toner image formed on the outer peripheral surface of the photosensitive drum 14 is first applied with a high voltage by the pre-transfer charger 19 and then fed into a plurality of recording sheets P, for example, classified by size. From any of the units 23, 24, and 25, the recording paper P to be transferred is conveyed to a transfer region between the photosensitive drum 14 and the transfer charger 20 through timing setting by the registration roller 26, etc. The recording paper P that has reached the transfer region is transferred from the outer peripheral surface of the photosensitive drum 14 by the separation charger 21 after the toner image on the outer peripheral surface of the photosensitive drum 14 is transferred by corona discharge or the like of the transfer charger 20. The Rukoto.

  On the other hand, the photosensitive drum 14 after the transfer process is prepared for the next image formation by removing the developer remaining on the outer peripheral surface by the cleaner 22.

  Further, the image forming apparatus 1 includes a fixing device 27 that performs fixing processing by supplying heat and applying pressure, and a conveyance belt 28 that conveys the recording paper P on which the toner image is transferred in the transfer region to the fixing device 27. , A flapper 29, an intermediate tray 30, and a staple sorter 31 or a bookbinding device (group binder) 32.

  The flapper 29 provided in the image forming apparatus 1 transfers the recording paper P that has been subjected to the fixing process by the fixing unit 27 based on the control of the control unit 12 to the intermediate tray 30 or the staple sorter 31 (to the image forming apparatus 1). When the glue binder 32 is provided, it is conveyed to one of the glue binders 32).

  The intermediate tray 30 provided in the image forming apparatus 1 is a so-called multiple mode in which a plurality of images are formed on the same surface of the recording paper P conveyed via the conveying rollers 33, 34, 35, 36. When the transfer mode is executed, the sheet is conveyed to the re-conveying roller 37 without being turned upside down. On the other hand, a mode in which an image is formed on both sides of the same recording paper P, so-called duplex copying mode is executed. In such a case, the paper is reversed and conveyed to the re-conveying roller 37.

  The re-conveying roller 37 provided in the image forming apparatus 1 conveys the recording paper P conveyed from the intermediate tray 30 to the registration roller 26, and thus the recording reaching the registration roller 26. The paper P is again transported to the transfer area and subjected to a transfer process. Next, the paper P is transported to the fixing device 27 by the transport belt 28 and subjected to the fixing process, and then is fed to the staple sorter 31 or the glue binder 32. The paper is ejected.

  The staple sorter 31 has a plurality of sheets subjected to fixing processing within a predetermined number of sheets when a mode in which a plurality of recording sheets P are continuously formed, that is, when a so-called continuous copying mode is executed. In the case where the recording sheet P is an apparatus that can sort one recording sheet P for each bin 31A and the image forming apparatus 1 includes the staple sorter 31, the staple unit 31B is stapled based on the control of the controller unit 12. Is set to execute.

  On the other hand, the glue binder 32 is a device capable of binding a plurality of recording papers P subjected to fixing processing. When the glue binder 32 is provided in the image forming apparatus 1, the binder portion 32A is controlled by the control portion 12. Based on this control, the back cover is glued to a bundle of paper sheets made up of a plurality of recording papers P to which the fixing process has been applied, and set in a stacker 32B.

  Next, the controller unit 12 provided in the image forming apparatus 1 will be described with reference to FIG. FIG. 5 is a block diagram showing a schematic configuration of the controller unit 12.

  The controller unit 12 controls the entire image forming apparatus and performs image processing on digital data input from the CCD unit 8 in accordance with a manual operation of the operation panel 13 by a user. A CPU 38 mainly responsible for control, a ROM 39 in which control procedures (control programs) of the entire apparatus are stored in advance, a RAM 40 as a main storage used as a storage of input data, a working storage area, etc., and an interface between the apparatuses And an image processing unit 42 that performs image processing on digital data input from the CCD unit 8 based on a manual operation of the user's operation panel 13.

  An address bus (not shown) and a data bus (not shown) of the CPU 38 of the controller unit 12 are connected to a ROM 39, a RAM 40, an I / O port 41, and an image processing unit 42 via a bus driver / address decoder circuit 43. It is connected.

  The I / O port 41 of the controller unit 12 includes an operation panel 13, motors 44 for driving main devices such as a motor for driving an optical scanning unit provided in the image forming apparatus 1, and an electromagnetic clutch. 45 and electromagnetic solenoids 46, for example, paper detection sensors 47 for detecting the recording paper P conveyed to the transfer area, and toner remaining amount detection for detecting the amount of toner contained in the developing device 18. A sensor 48, a primary charger 16, a pre-transfer charger 19, a high-voltage unit 51 for outputting a high voltage to the transfer charger 20, and a separation charger 21; and a non-image area on the outer peripheral surface of the photosensitive drum 14. It is connected to a beam detection sensor 52 for receiving the laser La emitted from the laser unit 17.

  Next, the image processing unit 42 included in the controller unit 12 will be described with reference to FIG. FIG. 6 is a block diagram showing a schematic configuration of the image processing unit 42.

  In the image processing unit 42, first, the CCD unit 8 converts analog data into digital data, the shading circuit 53 corrects the pixel-to-pixel variation, and then the scaling circuit 54 converts the image onto the recording paper P. When the mode to be formed is the reduced copy mode, digital data thinning processing is performed. On the other hand, when the mode for forming an image on the recording paper P is the enlarged copy mode, digital data interpolation processing is performed. Further, an error signal is output from the shading circuit 53 to the I / O port 41.

  Next, the digital data that has been either thinned out or interpolated by the scaling circuit 54 is subjected to edge differentiation of the image by, for example, second-order differentiation in a 5 × 5 window by the edge enhancement circuit 55. Is emphasized.

  Since the digital data edge-enhanced by the edge enhancement circuit 55 is luminance data, it is necessary to convert it into density data in order to output the digital data to the laser unit 17, and tones such as intermediate density. In order to change the expression according to the mode for forming an image on the recording paper P, the data is converted from luminance data to density data by a table search of the γ conversion circuit 56 and further input to the synthesis circuit 58.

  Next, the synthesizing circuit 58 to which the digital data is inputted selectively or ORs the inputted digital data and the image data in the image memory 59 constituted by, for example, a DRAM or the like. In particular, the data is output to the data conversion circuit 60. The read / write control for the image memory 59 is set to be performed by the memory control unit 61.

  Therefore, the digital data input to the data conversion circuit 60 has a pulse corresponding to the image forming mode set based on the manual operation of the user's operation panel 13 and corresponds to each light source of the laser unit 17. In this way, digital data is generated and output to the laser unit 17.

  Next, the operation panel 13 provided in the image forming apparatus 1 will be described with reference to FIG. FIG. 7 is a plan view showing a schematic configuration of the operation panel 13.

  The operation panel 13 allows the user to manually operate a transfer and fixing mode, the number of recording sheets P as a sheet-like transfer material on which an image is formed, or an image formed on the recording sheet P. This is an apparatus for instructing image processing performed by the controller unit 12 by setting density and the like.

  Therefore, the operation panel 13 is in the form of a known touch panel, and includes a display unit 63 as a display means, a numeric keypad 64, a start key 65, a reset key 66, a stop key 67, a clear key 68, A # key 69, an ID key 70, a residual heat key 71, an interrupt key 72, a power indicator lamp 73, and a power switch 74 are provided.

  The display unit 63 of the operation panel 13 can display an instruction to the user with a message or the like, and the numeric keypad 64 is a key for the user to input the number of copies.

  The start key 65 of the operation panel 13 is a key for instructing the image forming apparatus 1 to start image formation, and the reset key 66 is a key for returning the mode setting to the initial setting. .

  Further, the stop key 67 of the operation panel 13 is a key for interrupting all operations of the image forming apparatus 1, and the clear key 68 returns the number of copies input by the ten key 64 to the initial setting value. It is a key for.

  The # key 69 of the operation panel 13 is a key for use as an option attached to the image forming apparatus 1, and the ID key 70 is a function that can be operated only by a specific user. This is a key having an ID function.

  Further, the residual heat key 71 of the operation panel 13 is a key for turning on / off the residual heat mode, and the interrupt key 72 is a key for interrupting the middle of the copying operation to form another image. The display lamp 73 informs by “light” that the image forming apparatus 1 is not energized.

  Further, the power switch 74 of the operation panel 13 energizes a DC power source (not shown) and a secondary circuit (not shown) connected to the DC power source when the image forming apparatus 1 is OFF. In addition, a primary circuit (not shown) connected to the DC power supply and the display unit 61 are turned off. On the other hand, when the image forming apparatus 1 is turned on, the DC power supply, the primary circuit, the secondary circuit, This is to turn all the display units 61 on.

Next, the laser unit 17 and the like provided in the image forming apparatus 1 will be described with reference to FIG. Reference numeral 8 denotes a schematic configuration of the laser unit 17 and the like.

  The laser unit 17 is a device for converting the digital data generated by the controller unit 12 into a light beam and scanning and exposing the light beam to form a latent image corresponding to the digital data.

  The laser unit 17 includes a laser emission unit 101, a polygon mirror 102, a polygon motor 103 for rotating the polygon mirror 102, an imaging lens 104, a reflection mirror 105, and a beam detection sensor 52. The BD reflection mirror 107 for making the laser beam incident is provided. The laser beam reflected by the reflection mirror 105 exposes and scans the photosensitive drum 14 to form a latent image on the photosensitive drum 14.

  The laser light emitting unit 101 is a semiconductor laser having two light emitting units at intervals of 80 μm, and is tilted so that the scanning line interval of two laser beams (A laser and B laser) on the photosensitive drum 14 becomes a predetermined value. Has been placed.

  Next, the configuration of the temperature control device for the photosensitive drum 14 will be described with reference to FIG.

  A heater 901 is installed inside the photosensitive drum 14. As a means for detecting the temperature of the surface of the photoreceptor, there are a thermopile temperature sensor 902 and a non-contact type thermistor 903, and output signals 902s and 903s are input to the control circuit 904, respectively. The control circuit 904 detects the photoreceptor surface temperature based on the output signals 902 s and 903 s, outputs the output signal 904 s to drive the SW circuit 905, and controls the supply of power supplied from the AC power source 906 to the heater 901. Thus, the photoreceptor surface temperature is kept constant. Reference numeral 907 denotes a fan that sucks out ozone through a predetermined flow path so that ozone generated by corona discharge of the primary charger 16 does not adversely affect the photoreceptor.

  As described with reference to FIG. 4, the thermopile temperature sensor 903 is disposed to face the photosensitive drum so that infrared rays emitted from the surface of the photosensitive member can be detected through the lens. The thermopile type temperature sensor is composed of a thermopile element that detects a relative temperature and a thermistor that detects an absolute temperature.

  On the other hand, the non-contact thermistor 903 is installed, for example, at a position where the distance between the photosensitive drum and the non-contact thermistor 903 is 1 mm or less so that the surface temperature of the photosensitive drum can be detected by convection heat near the photosensitive drum. ing.

  Here, typical temperature detection accuracy and conditions of these two temperature detection means will be described.

The initial temperature detection accuracy including the receiving circuit of the thermopile temperature sensor is roughly determined by the following two conditions.
1) Accuracy of thermopile temperature sensor: ± 0.5 ° C due to adjustment during manufacturing
2) Accuracy of receiving circuit: ± 0.5 ° C
As a result, there is a variation of ± 1.0 ° C. as a whole.

  Since the thermopile temperature sensor collects light with a lens, the detected temperature does not deviate with respect to the variation in the distance between the photosensitive drum and the sensor within the normal mounting tolerance. However, considering the post-endurance associated with the operation of the apparatus as described above, the accumulation of dirt on the lens reduces the amount of infrared rays that pass through the lens and shifts the detection temperature to the lower side. Since this deviation amount depends on the degree of contamination, a very large deviation must be taken into consideration when considering the worst state in which proper maintenance has not been performed.

On the other hand, the non-contact thermistor is a single thermistor arranged so that the distance from the photosensitive drum is within 1 mm. The initial temperature detection accuracy of the non-contact thermistor is determined by the following four conditions. Typical values are
1) Thermistor accuracy: ± 0.5 ° C
2) Accuracy of receiving circuit: ± 0.5 ° C
3) Distance between photosensitive drum and thermistor: ± 1 ° C (for distance variation of 0.6 mm ± 0.2 mm)
4) Influence of air flow: ± 1 ° C (in the case of air flow in this embodiment)
And has a variation of ± 3.0 ° C. as a whole. Among these, the influence of the air flow of 4) can be eliminated by the configuration of the present invention, and the variation of ± 2.0 ° C. can be suppressed as a whole. Since this non-contact thermistor detects convection heat, the influence of dirt due to durability is ignored. Therefore, initially, the temperature detection accuracy does not change even after endurance accompanying the operation of the apparatus. Thus, although the thermopile type temperature sensor has better initial temperature detection accuracy, it can be seen that the thermopile type temperature sensor causes a temperature shift due to durability.

  The configuration of the control circuit 904 will be described with reference to FIG. FIG. 10A is a block diagram of the control circuit 904.

  Since the thermistor is greatly affected by the surrounding airflow, the fan 907 is stopped by the fan control means to eliminate the influence of the airflow when temperature detection is performed by the thermistor. Then, after the temperature detection is completed, the rotation of the fan 907 is controlled appropriately. An output signal 902s of the thermopile temperature sensor 902 is input to a comparator 1001 including a receiving circuit. The comparator 1001 is configured to output an off signal 1001s when the output signal 902s of the thermopile temperature sensor 902 exceeds 39 ° C.

  An output signal 903 s of the non-contact thermistor 903 is input to a comparator 1002 including a receiving circuit. The comparator 1002 is configured to output an off signal 1002 s when the output signal 903 s of the non-contact thermistor 903 exceeds 43 ° C. The off signal 1001 s and the off signal 1002 s are input to the OR circuit 1003, and the output signal 1003 s is input to the SW circuit 905. The SW circuit 905 controls the supply of power supplied from the AC power source 906 to the heater 901 in accordance with the output signal 1003s from the OR circuit.

  Here, temperature control performed by these circuit configurations will be described with reference to FIG.

  Initially, as shown in <(A) Initial state>, the temperature setting of the comparator 1001 is 39 ° C., and due to the variation of the thermopile type temperature sensor described above, the OFF output range (38 100 ° C. to 40 ° C.), an off signal 1001s is output.

  On the other hand, the temperature setting of the comparator 1002 is 44 ° C., and the off signal 1002s is actually output in the off output range (42 ° C. to 46 ° C.) due to the variation of the non-contact thermistor described above. Thus, since the off output range (38 ° C. to 40 ° C.) of the comparator 1001 is set lower than the off output range (42 ° C. to 46 ° C.) of the comparator 1002, the initial value can be obtained even if variations in detection accuracy are included. The temperature is controlled by the off output 1001s of the comparator 1001.

  However, after the endurance of the apparatus, dirt adheres to the lens portion of the thermopile type temperature sensor and the detected temperature shifts to the lower side. The state is shown in <(A) After Durability 1>, and a deviation occurs in the OFF output range of the comparator 1001 due to the deviation of the output of the thermopile temperature sensor with respect to the actual surface temperature of the photosensitive drum. In this state, depending on the variation of the thermopile temperature sensor and the variation of the non-contact thermistor, a state <region Ter> in which the comparator 1002 operates at a lower temperature than the comparator 1001 occurs, which is desirable when appropriate maintenance has been performed. Since it is not in a state, the service person or user is informed that the thermopile temperature sensor 902 has become dirty and prompts cleaning.

  As a worst state in which the dirt of the thermopile further accumulates as a result of neglecting proper maintenance, a state <(c) after endurance 2> in which the comparator 1002 operates at a lower temperature than the comparator 1001 including all variations is considered. Even in this state, the photosensitive drum is controlled between 42 ° C. and 46 ° C. by the temperature detection operation by the non-contact thermistor, so that the apparatus does not break down due to the melting / solidification of the toner.

  As described above, in the configuration of the present embodiment, the temperature detection by the non-contact thermistor is performed by eliminating the air flow around the non-contact thermistor and performing the temperature detection by the non-contact thermistor. By acting as a limiter, it can be seen that when the thermopile temperature sensor becomes dirty, the temperature does not become abnormal so as to cause a failure of the apparatus.

  In the embodiment described above, an example in which a non-contact thermistor is used as the second temperature detecting means has been described. However, a thermistor-type non-contact temperature sensor (for example, an NC sensor manufactured by Ishizuka Electronics) is also used. However, the same effect can be obtained.

  Further, although the temperature control of the photosensitive drum has been described as an example, the configuration of the present invention is effective when the temperature of the fixing member is controlled in the fixing device, and the same effect can be obtained.

1 is a schematic configuration diagram of an image forming apparatus. It is sectional drawing of the photosensitive drum which shows the conventional temperature detection apparatus. It is sectional drawing of the photosensitive drum which shows the conventional temperature detection apparatus. It is a block diagram of a thermal pile type temperature sensor. 2 is a block diagram illustrating a schematic configuration of a controller unit of the image forming apparatus. FIG. 2 is a block diagram illustrating a schematic configuration of an image processing unit of the image forming apparatus. FIG. 2 is a plan view illustrating a schematic configuration of an operation panel of the image forming apparatus. FIG. It is a schematic block diagram of a laser unit etc. It is a block diagram which shows the structure of the temperature control apparatus which concerns on this invention. It is a block diagram of the control circuit of the temperature control apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Controller part 14 Photosensitive drum 17 Laser unit 901 Heater 902 Thermopile type temperature sensor 903 Non-contact type thermistor 904 Control circuit 905 SW circuit 906 AC power supply 907 Fan

Claims (24)

A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
A first non-contact temperature detecting means which is provided in a non-contact manner on the heated body and detects the temperature of the heated body according to the amount of infrared rays emitted from the heated body;
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow generating means for generating an air flow,
A temperature detecting device characterized in that when temperature detection is performed by the first or second non-contact temperature sensor, detection is performed after the airflow generating means is stopped or suppressed. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
A first non-contact temperature detecting means which is provided in a non-contact manner on the heated body and detects the temperature of the heated body according to the amount of infrared rays emitted from the heated body;
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow generating means for generating an air flow,
When performing temperature detection with the first or second non-contact temperature sensor, the detection is performed after stopping or suppressing the air flow generating means,
A temperature detection apparatus that corrects the detection information of the first non-contact temperature detection means based on the detection information of the second non-contact temperature detection means. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
1st non-contact temperature detection which is provided in the said to-be-heated body in non-contact, condenses the infrared rays radiated | emitted from the to-be-heated body through a condensing means, and detects the temperature of the said to-be-heated body according to the amount of infrared rays Means,
A second non-contact temperature detecting means that is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body; An air flow generating means for generating a flow,
When performing temperature detection with the first or second non-contact temperature sensor, the detection is performed after stopping or suppressing the air flow generating means,
A temperature detection apparatus, characterized in that a reference correction value of detection information of the second non-contact temperature detection means is generated from detection information of the first non-contact temperature detection means. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
1st non-contact temperature detection which is provided in the said to-be-heated body in non-contact, condenses the infrared rays radiated | emitted from the to-be-heated body through a condensing means, and detects the temperature of the said to-be-heated body according to the amount of infrared rays Means,
A second non-contact temperature detecting means that is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body; An air flow generating means for generating a flow,
When performing temperature detection with the first or second non-contact temperature sensor, the detection is performed after stopping or suppressing the air flow generating means,
A temperature detecting device, wherein when the detection information of the second non-contact temperature detecting means exceeds a predetermined range, it is determined that the first non-contact temperature detecting means is abnormal. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
A first non-contact temperature detecting means which is provided in a non-contact manner on the heated body and detects the temperature of the heated body according to the amount of infrared rays emitted from the heated body;
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow blocking means for blocking air flow around the first or second non-contact sensor,
When performing temperature detection by the first or second non-contact temperature sensor, the temperature is detected after the air flow blocking means interrupts the flow of air around the first or second non-contact sensor. Detection device. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
A first non-contact temperature detecting means which is provided in a non-contact manner on the heated body and detects the temperature of the heated body according to the amount of infrared rays emitted from the heated body;
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow blocking means for blocking air flow around the first or second non-contact sensor,
When performing temperature detection by the first or second non-contact temperature sensor, the air flow blocking means is used to detect air flow around the first or second non-contact sensor.
A temperature detection apparatus that corrects the detection information of the first non-contact temperature detection means based on the detection information of the second non-contact temperature detection means. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
A first non-contact temperature that is provided in a non-contact manner on the heated body, collects infrared rays radiated from the heated body through condensing means, and detects the temperature of the heated body according to the amount of infrared rays. Detection means;
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow blocking means for blocking air flow around the first or second non-contact sensor,
When performing temperature detection by the first or second non-contact temperature sensor, the air flow blocking means performs detection after blocking the air flow around the first or second non-contact sensor,
A temperature detection apparatus, characterized in that a reference correction value of detection information of the second non-contact temperature detection means is generated from detection information of the first non-contact temperature detection means. A temperature detecting device for detecting the temperature of a heated object heated by a heating means,
1st non-contact temperature detection which is provided in the said to-be-heated body in non-contact, condenses the infrared rays radiated | emitted from the to-be-heated body through a condensing means, and detects the temperature of the to-be-heated body according to infrared rays amount Means,
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow blocking means for blocking air flow around the first or second non-contact sensor,
When performing temperature detection by the first or second non-contact temperature sensor, the air flow blocking means performs detection after blocking the air flow around the first or second non-contact sensor,
A temperature detecting device, wherein when the detection information of the second non-contact temperature detecting means exceeds a predetermined range, it is determined that the first non-contact temperature detecting means is abnormal.   The temperature detection apparatus according to claim 1, wherein the heated body is a photoconductor.   The temperature detecting device according to claim 1, wherein the heated body is a fixing member.   The temperature detection apparatus according to claim 1, wherein the first temperature detection means is a thermopile type temperature sensor.   The temperature detecting device according to claim 11, wherein the thermopile type temperature sensor includes a thermopile element and at least one thermistor.   The temperature detection device according to claim 1, wherein the second temperature detection means is a thermistor.   9. The temperature detecting device according to claim 1, wherein the second temperature detecting means is a thermistor type non-contact temperature sensor.   The temperature detection device according to claim 1, wherein the airflow generation means is a fan. A temperature control device that detects the temperature of the heated object heated by the heating means and controls the temperature of the heated object by controlling the heating means,
1st non-contact temperature detection which is provided in the said to-be-heated body in non-contact, condenses the infrared rays radiated | emitted from the to-be-heated body through a condensing means, and detects the temperature of the said to-be-heated body according to the amount of infrared rays Means,
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow generating means for generating an air flow,
When performing temperature detection with the first or second non-contact temperature sensor, the detection is performed after stopping or suppressing the air flow generating means,
First temperature control means for controlling the temperature of the object to be heated by controlling the heating means based on detection information from the first temperature detection means;
A temperature control apparatus, wherein when the detection information of the second non-contact temperature detection means exceeds a predetermined range, heating of the heated object by the heating means is stopped. A temperature control device that detects the temperature of the heated object heated by the heating means and controls the temperature of the heated object by controlling the heating means,
1st non-contact temperature detection which is provided in the said to-be-heated body in non-contact, condenses the infrared rays radiated | emitted from the to-be-heated body through a condensing means, and detects the temperature of the said to-be-heated body according to the amount of infrared rays Means,
A second non-contact temperature detecting means which is provided in a non-contact manner on the heated body and directly detects the amount of convective heat or infrared rays from the heated body to detect the temperature of the heated body;
An air flow blocking means for blocking air flow around the first or second non-contact sensor,
When performing temperature detection by the first or second non-contact temperature sensor, the air flow blocking means performs detection after blocking the air flow around the first or second non-contact sensor,
First temperature control means for controlling the temperature of the object to be heated by controlling the heating means based on detection information from the first temperature detection means;
A temperature control apparatus, wherein when the detection information of the second non-contact temperature detection means exceeds a predetermined range, heating of the heated object by the heating means is stopped.   18. The temperature control apparatus according to claim 16, wherein the heated body is a photosensitive body.   18. The temperature control apparatus according to claim 16, wherein the heated body is a fixing member.   18. The temperature control apparatus according to claim 16, wherein the first temperature detecting means is a thermopile type temperature sensor.   The temperature control device according to claim 20, wherein the thermopile temperature sensor includes a thermopile element and at least one thermistor.   18. The temperature control apparatus according to claim 16, wherein the second temperature detection means is a thermistor.   18. The temperature control apparatus according to claim 16, wherein the second temperature detecting means is a thermistor type non-contact temperature sensor.   The temperature control device according to claim 16, wherein the airflow generating means is a fan.

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