JP2005321213A - Temperature sensor, temperature measuring device, temperature control device, fixing device and imaging forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncontact type temperature sensor contributing to suppression of an error in temperature measurement of a heating body, a temperature measuring device equipped with the temperature sensor, a temperature control device, a fixing device, and an image forming device equipped with the fixing device. <P>SOLUTION: This temperature sensor is equipped with the first element arranged on a position separated from the heating body which is a measuring object and receiving a radiation heat from the heating body, and having a resistance value changing corresponding to the temperature; and the second element arranged on a position separated from the heating body and avoiding the radiation heat from the heating body, and having a resistance value changing corresponding to the temperature. The first element and the second element are such elements that the difference between the resistance value of the first element and the resistance value of the second element when both the first element and the second element have the same temperature has the minimum value at some temperature in a temperature measuring range of the second element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temperature sensor that measures the temperature of a heating element to be measured in a non-contact state, a temperature measuring device provided with such a temperature sensor, a temperature control device, a fixing device, and such a fixing device. The present invention relates to an image forming apparatus provided.

  Conventionally, a printer or the like that forms a toner image on the surface of an image carrier such as a photoreceptor roll, and finally transfers and fixes the formed toner image on a recording medium such as a recording sheet. The image forming apparatus is known.

  Some of these image forming apparatuses are provided with a fixing device having a rotatable pressure roll and a heating roll. In an image forming apparatus provided with such a fixing device, a toner image is transferred. The recording medium is fed into a nip formed between a rotating pressure roll and a heating roll, and the toner image transferred onto the recording paper is melted and pressed while passing through the nip. The toner image is fixed on the recording medium.

  The toner image in the fixing device as described above is melted by a heating roll, and fine control of the roll temperature is indispensable for stabilizing the quality of the image formed on the recording medium.

  However, if the temperature of the rotating heating roll is detected by using a contact-type temperature sensor, the heating roll may be damaged. If the heating roll is damaged, the fixing of the toner image onto the recording medium is adversely affected. Will be affected.

  Then, the proposal which intends to solve the said problem using the non-contact type temperature sensor is made | formed (for example, refer patent document 1).

  Japanese Patent Application Laid-Open No. H11-260260 proposes a device in which the non-contact type temperature sensor is provided in the paper passing range of the recording paper and the contact type temperature sensor is provided in the non-paper passing range.

  In the non-contact type temperature sensor in this proposal, the resistance value varies depending on the temperature, and the difference between the resistance values is minimized in the vicinity of 180 ° C., which is the temperature when the heating roll is relatively hot. The elements are respectively disposed at a position where the radiant heat from the heating roll is received and a position where the radiant heat is avoided.

In the above proposal, when the temperature of the heating roll is relatively low, the temperature based on the data from the contact type temperature sensor is set as the temperature of the heating roll, and when the temperature of the heating roll is relatively high, the non-contact type The temperature based on the data from the temperature sensor is used as the temperature of the heating roll. The reason why the data to be adopted is changed depending on the temperature of the heating roll is that the data sent from the above-mentioned non-contact type temperature sensor when the temperature of the heating roll is relatively low includes many errors It is.
JP 2003-91203 A

  However, the above proposal has a problem that a contact-type temperature sensor must be provided in addition to the non-contact type in order to accurately control the temperature of the heating roll.

  Note that this problem does not occur only when the temperature control of the heating roll is accurately performed, but similarly occurs when the temperature of the heating element to be measured is measured by a non-contact sensor.

  In view of the above circumstances, the present invention is a non-contact type temperature sensor that contributes to suppression of errors in temperature measurement of a heating element, a temperature measurement device provided with such a temperature sensor, a temperature control device, a fixing device, and An object of the present invention is to provide an image forming apparatus provided with such a fixing device.

In order to achieve the above object, the temperature sensor of the present invention comprises:
A first element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element to be measured and receiving radiant heat from the heating element;
A second element that is disposed away from the heating element and avoids radiant heat from the heating element, the resistance value of which varies with temperature,
The first element and the second element have a resistance value between the first element and the second element when both the first element and the second element are at the same temperature. The difference is an element having a minimum value at any temperature within the temperature measurement range of the second element.

In order to achieve the above object, the temperature measuring device of the present invention comprises:
A first element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element to be measured and receiving radiant heat from the heating element;
A second element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element and avoiding radiant heat from the heating element;
A temperature measuring unit for determining the temperature of the heating element based on the resistance value of the first element and the resistance value of the second element;
The first element and the second element have a resistance value between the first element and the second element when both the first element and the second element are at the same temperature. The difference is an element having a minimum value at any temperature within the temperature measurement range of the second element.

  The present invention relates to a first element and a second element arranged in a non-contact type temperature sensor, and the first element and the second element when both the first element and the second element are at the same temperature. It is more conventional to use the element whose difference between the resistance value and the resistance value of the second element is the minimum value at any temperature within the temperature measurement range of the second element. The temperature measurement error of the heating element is smaller than when an element having a minimum resistance difference at any temperature within the temperature measurement range of the first element that measures a temperature range relatively higher than the measurement range is used. Based on what the present inventors have found that the temperature can be reduced, the temperature measuring device of the present invention using the temperature sensor of the present invention can suppress the temperature detection error of the heating element.

Here, a first resistor connected in series to the first element;
A second resistor connected in series to the second element,
The temperature measuring unit is based on both a first partial pressure by the first element and the first resistor and a second partial pressure by the second element and the second resistor. Determining the temperature of the heating element,
The first element and the second element have a resistance value between the first element and the second element when both the first element and the second element are at the same temperature. An element whose difference is a minimum value at any temperature within the temperature measurement range of the second element,
The first resistor and the second resistor preferably have a resistance value within a resistance value change range of the second element within the temperature measurement range of the second element. .

  In this way, the temperature measurement error of the heating element can be further suppressed.

In order to achieve the above object, the temperature control device of the present invention comprises:
A first element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element to be measured and receiving radiant heat from the heating element;
A second element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element and avoiding radiant heat from the heating element;
A temperature measuring unit for determining the temperature of the heating element based on the resistance value of the first element and the resistance value of the second element;
A temperature control unit that controls the temperature of the heating element based on the measurement temperature obtained by the temperature measurement unit and the set temperature of the heating element;
The first element and the second element have a resistance value between the first element and the second element when both the first element and the second element are at the same temperature. The difference is an element having a minimum value at any temperature within the temperature measurement range of the second element.

In order to achieve the above object, the fixing device of the present invention comprises:
In a fixing device for melting and fixing a toner image transferred on a recording medium onto the recording medium,
A heat roll that melts the toner image, the calorific value changes according to the supplied power, and
A first element having a resistance value that varies depending on temperature, disposed at a position that is separated from the heat roll to be measured and receives radiant heat from the heat roll;
A second element having a resistance value that varies depending on the temperature, disposed at a position apart from the heat roll and avoiding radiant heat from the heat roll;
A temperature measuring unit for determining the temperature of the heat roll based on the resistance value of the first element and the resistance value of the second element;
A power control unit that controls power supply to the heat roll according to the temperature determined by the temperature measurement unit,
The first element and the second element have a resistance value between the first element and the second element when both the first element and the second element are at the same temperature. The difference is an element having a minimum value at any temperature within the temperature measurement range of the second element.

In order to achieve the above object, an image forming apparatus of the present invention comprises:
In an image forming apparatus for forming an image by forming a toner image on an image carrier and finally transferring and fixing the toner image on a recording medium.
A fixing device for melting and fixing the toner image transferred on the recording medium onto the recording medium;
This fixing device
A heat roll that melts the toner image, the calorific value changes according to the supplied power, and
A first element having a resistance value that varies depending on the temperature, disposed at a position apart from the heat roll to be measured and receiving radiant heat from the heat roll;
A second element having a resistance value that varies depending on temperature, disposed at a position apart from the heat roll and avoiding radiant heat from the heat roll;
A temperature measuring unit for determining the temperature of the heat roll based on the resistance value of the first element and the resistance value of the second element;
A power control unit that controls power supply to the heat roll according to the temperature determined by the temperature measurement unit,
The first element and the second element have a resistance value between the first element and the second element when both the first element and the second element are at the same temperature. The difference is an element having a minimum value at any temperature within the temperature measurement range of the second element.

  In the temperature measuring device, temperature control device, fixing device, and image forming apparatus of the present invention using the temperature sensor of the present invention, it is possible to accurately grasp the temperature of the heating element.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a main part of a printer which is an embodiment of an image forming apparatus of the present invention.

  The printer 1 of the present embodiment shown in FIG. 1 includes four image forming units 10Y, 10M, 10C, and 10K. Each of the image forming units has a photoreceptor roll 11Y, 11M, 11C, and 11K, chargers 12Y, 12M, 12C, and 12K, exposure devices 13Y, 13M, 13C, and 13K, developing rolls 14Y, 14M, 14C, and 14K, and primary transfer rolls 15Y, 15M, 15C, and 15K. The printer 1 is capable of full-color printing, and the symbols Y, M, C, and K added to the end of each component described above are yellow, magenta, cyan, and black images, respectively. It is a component for formation.

  The printer 1 also includes an intermediate transfer belt 30, a secondary transfer roll 32, a fixing device 33, and a central control unit 35.

  A basic image forming operation in the printer 1 will be described.

  First, toner image formation by the yellow image forming unit 10Y is started, and a predetermined charge is applied to the surface of the photoreceptor roll 11Y rotating in the direction of arrow A by the contact charger 12Y. Next, the exposure device 13Y irradiates the surface of the photoreceptor roll 11Y with exposure light corresponding to a yellow image to form a latent image. The latent image is developed with yellow toner by the developing roll 14Y, and a yellow toner image is formed on the photoreceptor roll 11Y. The toner image is transferred to the intermediate transfer belt 30 by the primary transfer roll 15Y.

  The intermediate transfer belt 30 circulates in the direction of arrow B, and is synchronized with the timing at which the yellow toner image transferred onto the intermediate transfer belt 30 reaches the primary transfer roll 15M of the next color image forming unit 10M. The magenta image forming unit 10M forms a toner image so that the next color magenta toner image reaches the primary transfer roll 15M. The magenta toner image formed in this way is transferred onto the yellow toner image on the intermediate transfer belt 30 by the primary transfer roll 15M.

  Subsequently, toner image formation by the cyan and black image forming units 10C and 10K is performed at the same timing as described above, and sequentially superimposed on the yellow and magenta toner images of the intermediate transfer belt 30 in the primary transfer rolls 15C and 15K. Is transcribed.

  In this way, the multicolor toner image transferred onto the intermediate transfer belt 30 is secondarily transferred onto the paper 200 by the secondary transfer roll 32, and the multicolor toner image is conveyed along with the paper 200 in the direction of arrow C to be pressed. Fixing is performed by heating and pressure-bonding on the paper 200 by a fixing device 33 including a roll 33a, a heating roll 33b, and a temperature sensor 33c.

  The printer 1 is provided with a control circuit (see FIG. 2) for controlling the temperature of the heating roll 33b, and the image quality is stabilized by finely controlling the temperature of the heating roll 33b. .

  Here, with reference to FIG. 2, a fixing device 33 that is an embodiment of the fixing device of the present invention and a temperature sensor 33 c that is an embodiment of the temperature sensor of the present invention, which is a component of the fixing device 33. While explaining.

  FIG. 2 is a schematic diagram of a fixing device that is an embodiment of the fixing device of the present invention and a control circuit that performs temperature management of the heating roll.

  The fixing device 33 shown on the left in FIG. 2 includes a pressure roll 33a (see FIG. 1), a heating roll 33b, and a temperature sensor 33c.

  The control circuit 31 includes a detection resistor R5, a compensation resistor R6, an amplifier circuit 313, a CPU 314, and a photo switch 315, which will be described in detail later. The fixing device 33, the detection resistor R5 of the control circuit 31, the compensation resistor R6, the amplifier circuit 313, and the CPU 314 correspond to an embodiment of the temperature measuring device of the present invention, and the fixing device 33 and the control circuit. 31 corresponds to an embodiment of the temperature control device of the present invention.

  FIG. 3 is an external perspective view of the temperature sensor shown in FIG.

  A temperature sensor 33c shown in FIG. 3 includes an infrared absorption film 335c that absorbs radiant heat from the heating roll 33b, a housing 333c that includes a window 3331c, and a housing 333c that is disposed at a position apart from the heating roll 33b. A signal line 334c for outputting a signal corresponding to the detected temperature to the control circuit 31 shown in FIG.

  4 is a cross-sectional view of the temperature sensor shown in FIG.

  FIG. 4 shows a case where the cut portion of the temperature sensor 33c, which is indicated by a dotted line in FIG. 3, is viewed in the direction of XX ′. Inside the housing 333c is a component of the temperature sensor 33c. A state where a detection element 331c and a compensation element 332c are attached to the infrared absorption film 335c is shown. In this image forming apparatus 1, a temperature of 200 ° C. or higher is detected by the sensing element 331c, while a temperature up to around 100 ° C. is detected by the compensating element 332c.

  The detection element 331c is disposed at a position that receives radiant heat from the heating roll 33b through a window 3331c provided in the casing 333c, and the compensation element 332c is a space provided in the casing that avoids radiant heat from the heating roll 33b. 3332c.

  The detection element 331c and the compensation element 332c included in the temperature sensor 33c of the image forming apparatus 1 of the present embodiment are elements that minimize the difference between these resistance values when the temperature is at 80 ° C. The compensation element 332c is an element whose resistance value changes in the range of 23 kΩ to 440 kΩ when the temperature changes from 20 ° C. to 120 ° C. Hereinafter, the story is returned to the description of FIG.

  As described above, the control circuit 31 shown in FIG. 2 includes the detection resistor R5, the compensation resistor R6, the amplifier circuit 313, the CPU 314, and the photoswitch 315, and the detection resistor R5 is connected in series to the detection element 331c. The compensation resistor R6 is connected in series to the compensation element 332c. Note that a voltage of 3.3 V is also applied to each of the series connections.

  The amplifier circuit 313 includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a first operational amplifier 3131 shown on the left side in FIG. 2, and a second operational amplifier 3132 shown on the right side in FIG.

  The input terminal of the first operational amplifier 3131 of the amplifier circuit 313 receives the divided voltage of the detection element 331c and the detection resistor R5 connected in series, and is connected to the output of the first operational amplifier 3131 and connected in series to the resistor R1. The resistor R2 and the divided voltage of the resistor 1 are input to the inverting input terminal of the first operational amplifier 3131.

  The output of the first operational amplifier 3131 is input to the inverting input terminal of the second operational amplifier 3132 of the amplifier circuit 313 via the resistor R3, and the divided voltage of the compensation element 332c and the compensation resistor R6 connected in series is Input to the input terminal. The inverting input terminal and the output terminal of the second operational amplifier 3132 are connected via a resistor R4.

  The CPU 314 has a voltage of 3.3 V (hereinafter referred to as Vref), an output voltage from the second operational amplifier 3132 (hereinafter referred to as Vamp), and a compensation element connected in series. The divided voltage of 332c and compensation resistor R6 (hereinafter, this divided voltage is referred to as Vc) is input, and in this CPU 314, Vamp is converted into a digital value ADamp, and Vc is converted into a digital value ADc.

  In the control circuit 31, the temperature of the heating roll is estimated from the following formula based on the digital values ADamp and ADc converted by the CPU 314. The AD conversion accuracy is 10 bits (1024).

  In the CPU 314 provided in the control circuit 31, for ADamp and ADc, Vc and Vamp calculated from the above formula (1) and the above formula (2), and the following formulas (3) and (4) are used. The resistance value of the sensing element 331c (hereinafter referred to as rd) and the resistance value of the compensation element 332c (hereinafter referred to as rc) are calculated. R1 to R6 shown below represent resistance values of the resistors R1 to R6.

  Here, α is an amplification factor of the partial voltage Vd of the detection element 331c and the detection resistor R5 connected in series, and is expressed by the following equation (5).

  In the CPU 314, the temperature (Tc) detected by the compensation element 332c calculated based on rd (kΩ) and rc (kΩ), the following expressions (6) and (7), and the detection element 331c The temperature Troll of the heating roll 33b is calculated from the temperature (Td) detected in step (8) using equation (8).

Note that ro (kΩ) and B (K) are element characteristic values, and F (K ⁻³ ) is the field shape of the window 3331c (see FIGS. 3 and 4) of the temperature sensor of the present embodiment. It is a proportionality constant that depends on.

  In the control circuit 31 shown in FIG. 2, the photo switch 315 is controlled based on the temperature of the heating roll 33b estimated as described above and a temperature management program prepared in advance. As a result, in this image forming apparatus 1, when the photo switch 315 is turned on, power is supplied to the heating roll 33b and the temperature of the heating roll rises. When the photo switch 315 is turned off, the power is cut off and the temperature of the heating roll is increased. Has come to decline.

  FIG. 5 is a graph showing the relationship between Vc and Vamp input to the CPU of the control circuit shown in FIG. 2 and the temperature of the heating roll estimated based on these in the image forming apparatus of the present embodiment. .

  FIG. 5 is a graph showing the conditions of Vc and Vamp when the temperature of the heating roll 33b is estimated every 0 ° C. to 20 ° C. The horizontal axis is Vc and the vertical axis is Vamp. In the image forming apparatus 1 of the present embodiment, both the detection resistor R5 and the compensation resistor R6 are 100 kΩ (α = 32).

  Here, as shown in FIG. 5, a method of calculating a temperature measurement error in the image forming apparatus 1 for estimating the temperature of the heating roll 33b will be described.

  FIG. 6 is a graph for the estimated temperature of the heating roll of 180 ° C., 200 ° C., and 220 ° C. in the graph shown in FIG.

  In FIG. 6, in addition to the conditions of Vc and Vamp when the temperature of the heating roll 33b is estimated from 180 ° C. to 220 ° C. every 20 ° C., the measured temperature of the heating roll 33b is 200 ° C. Vc and Vamp are shown in a graph, and the temperature measurement error σT at the point 'X' shown in FIG. 6 has the values ΔVamp, ΔTroll, σVamp, σVc, ∂Vamp / ∂Vc shown in FIG. 9), Equation (10), and Equation (11).

  When the temperature of the heating roll 33b is estimated from 0 ° C. to 260 ° C. in increments of 20 ° C., an error from the actually measured temperature is estimated for each of these temperatures by the above-described method. The measurement error is 6.38 ° C.

  Table 1 below shows that the temperature at which the difference between the resistance value of the sensing element 331c and the resistance value of the compensation element 332c at the same temperature is minimized is 10 ° C, 25 ° C, 80 ° C, 110 ° C, 140 ° C. The temperature when the resistance value of both the detection resistor R5 and the compensation resistor R6 is any one of 10 kΩ, 23 kΩ, 33 kΩ, 100 kΩ, 200 kΩ, 300 kΩ, 440 kΩ, and 985 kΩ. The average value of measurement error is shown.

  7 and 8 are graphs relating to the data shown in Table 1. FIG.

  FIG. 7A shows the temperature and temperature measurement at which the difference between the resistance value of the sensing element 331c and the resistance value of the compensating element 332c at the same temperature is minimized for each resistance value of the sensing resistor R5 and the compensation resistor R6. The relationship with the error (average value) is shown. The description of FIG. 7B will be given later.

  FIG. 8 shows the resistance values of the detection resistor R5 and the compensation resistor R6 and the temperature measurement error (average) for each temperature at which the difference between the resistance value of the detection element 331c and the resistance value of the compensation element 332c at the same temperature is minimized. Value), the temperature at which the difference between the resistance values is minimum is 80 ° C., and the resistance values of the detection resistor R5 and the compensation resistor R6 are both 100 kΩ, that is, image formation according to this embodiment. It has been shown that the temperature measurement error is minimal in the case of the apparatus 1 embodiment.

  7 and 8, the temperature at which the difference between the resistance value of the sensing element 331c and the resistance value of the compensation element 332c at the same temperature is minimized is the temperature detection range of 20 ° C. to 120 ° C. by the compensation element 332c. It can be read that the temperature measurement error is suppressed by setting any one of the above temperatures. As a result, temperature measurement errors due to factors other than electrical noise are suppressed, so that the degree of freedom in setting the detection resistor R5 and the compensation resistor R6 is increased, and circuit constants that are less susceptible to electrical noise can be selected. it can.

  7 and FIG. 8, the temperature at which the difference between the resistance value of the sensing element 331c and the resistance value of the compensation element 332c at the same temperature is minimized from the temperature detection range of 20 ° C. by the compensation element 332c. While the temperature is set to any one of 120 ° C., the resistance value of the compensation element 332c itself when the values of the detection resistor R5 and the compensation resistor R6 are detected from the temperature range 20 ° C. to 120 ° C. detected by the compensation element 332c. It can be read that the temperature measurement error can be further suppressed by setting the value between 23 kΩ and 440 kΩ, which is the change range of the.

  Further, from FIGS. 7 and 8, the temperature at which the difference between the resistance value of the sensing element 331c and the resistance value of the compensating element 332c at the same temperature is 80 ° C. is the value of the sensing resistor R5 and the compensating resistor R6. Is 100 kΩ, that is, it is read that the temperature measurement error is most suppressed by adopting the same form as the image forming apparatus 1. Therefore, according to this embodiment, the temperature of the heating roll can be accurately grasped, and the image quality can be stabilized.

  Finally, FIG. 7B will be described.

  FIG. 7B shows the temperature measurement error when an element having the smallest resistance error at 180 ° C. is used as the sensing element 331c and an element having the smallest resistance error at 80 ° C. is adopted as the compensating element 332c. When the two elements are employed, the difference between the resistance values of the two elements at the same temperature is 100 ° C. It can be read that it is minimized.

  From FIG.7 (b), although it seems that it seems reasonable that each resistance value is most stable in the temperature measurement range of each element as a sensing element and a compensation element, as a result, It can be read that the temperature measurement error becomes larger than that in the case of using a conventional element in which the temperature at which the difference between the resistance values of the two elements is minimum is 180 ° C.

  In the embodiment described above, the resistance values of the compensation element 332c itself when the resistance values of the detection resistor R5 and the compensation resistor R6 are detected in the temperature range of 20 ° C. to 120 ° C. detected by the compensation element 332c. However, the present invention has been described with reference to an example in which the temperature measurement error is further suppressed by setting the value within the change range. However, in the present invention, the resistance of the sensing element 331c at the same temperature is described. The temperature at which the difference between the value and the resistance value of the compensation element 332c is minimized may be any temperature within the temperature detection range of the compensation element 332c.

  In the embodiment described above, the case where the detection resistor R5 and the compensation resistor R6 have the same resistance value has been described as an example. However, the present invention is not limited to this, and the detection resistor R5 and the compensation resistor R6. Each of them may have any different resistance value within the range of change of its own resistance value within the temperature measurement range of the compensation element, and the detection resistor R5, the compensation resistor R6, and the amplifier circuit 313 may be A thing different from this embodiment may be sufficient.

  In the embodiment described above, the temperature measurement and temperature control of the heating roll 33b have been described as examples. However, the present invention may be directed to a heating element other than the heating roll.

1 is a schematic configuration diagram of a main part of a printer which is an embodiment of an image forming apparatus of the present invention. FIG. 3 is a schematic diagram of a fixing device that is an embodiment of the fixing device of the present invention and a control circuit that performs temperature management of a heating roll. It is an external appearance perspective view of the temperature sensor shown in FIG. It is sectional drawing of the temperature sensor shown in FIG. 3 is a graph showing the relationship between Vc and Vamp input to the CPU of the control circuit shown in FIG. 2 and the temperature of the heating roll estimated based on these in the image forming apparatus of the present embodiment. FIG. It is a graph figure about the estimated temperature of a heating roll among the graphs shown in FIG. 5 about 180 degreeC, 200 degreeC, and 220 degreeC. 2 is a graph regarding data shown in Table 1. FIG. 2 is a graph regarding data shown in Table 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer 31 Control circuit 313 Amplifier circuit 3131 1st operational amplifier 3132 2nd operational amplifier 314 CPU
315 Photo switch 33 Fixing device 33a Pressure roll 33b Heating roll 33c Temperature sensor 331c Detection element 332c Compensation element 333c Case 3331c Window 3332c Space 334c Signal line 335c Infrared absorption film R5 Detection resistance R6 Compensation resistance

Claims (6)

A first element having a resistance value that varies with temperature, disposed at a position away from the heating element to be measured and receiving radiant heat from the heating element;
A second element having a resistance value that varies depending on temperature, and is disposed at a position away from the heating element and avoiding radiant heat from the heating element;
The first element and the second element have a resistance value of the first element and a resistance value of the second element when both the first element and the second element are at the same temperature. A temperature sensor, wherein the difference is an element having a minimum value at any temperature within the temperature measurement range of the second element. A first element having a resistance value that varies with temperature, disposed at a position away from the heating element to be measured and receiving radiant heat from the heating element;
A second element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element and avoiding radiant heat from the heating element;
A temperature measuring unit for obtaining a temperature of the heating element based on a resistance value of the first element and a resistance value of the second element;
The first element and the second element have a resistance value of the first element and a resistance value of the second element when both the first element and the second element are at the same temperature. A temperature measuring apparatus, wherein the difference is an element having a minimum value at any temperature within the temperature measuring range of the second element. A first resistor connected in series to the first element;
A second resistor connected in series to the second element,
The temperature measuring unit is based on both a first partial pressure by the first element and the first resistor and a second partial pressure by the second element and the second resistor. Determining the temperature of the heating element,
The first element and the second element have a resistance value of the first element and a resistance value of the second element when both the first element and the second element are at the same temperature. An element having a minimum difference at any temperature within the temperature measurement range of the second element;
The first resistor and the second resistor have any resistance value within a resistance value change range of the second element within the temperature measurement range of the second element. The temperature measuring device according to claim 2. A first element having a resistance value that varies with temperature, disposed at a position away from the heating element to be measured and receiving radiant heat from the heating element;
A second element having a resistance value that varies depending on temperature, disposed at a position apart from the heating element and avoiding radiant heat from the heating element;
A temperature measuring unit for determining a temperature of the heating element based on a resistance value of the first element and a resistance value of the second element;
A temperature control unit that controls the temperature of the heating element based on the measurement temperature obtained by the temperature measurement unit and the set temperature of the heating element;
The first element and the second element have a resistance value of the first element and a resistance value of the second element when both the first element and the second element are at the same temperature. A temperature control device, wherein the difference is an element having a minimum value at any temperature within the temperature measurement range of the second element. In a fixing device for melting and fixing a toner image transferred on a recording medium onto the recording medium,
A heat roll that melts the toner image, the calorific value changes according to the supplied power, and
A first element having a resistance value that varies depending on temperature, disposed at a position that is separated from the heat roll to be measured and receives radiant heat from the heat roll;
A second element whose resistance value is changed according to temperature, which is disposed at a position away from the heat roll and avoiding radiant heat from the heat roll;
A temperature measuring unit for determining a temperature of the heat roll based on a resistance value of the first element and a resistance value of the second element;
A power control unit that controls power supply to the heat roll according to the temperature determined by the temperature measurement unit;
The first element and the second element have a resistance value of the first element and a resistance value of the second element when both the first element and the second element are at the same temperature. A fixing device, wherein the difference is an element having a minimum value at any temperature within a temperature measurement range of the second element. In an image forming apparatus for forming an image by forming a toner image on an image carrier, and finally transferring and fixing the toner image on a recording medium.
A fixing device for melting and fixing the toner image transferred on the recording medium onto the recording medium;
The fixing device is
A heat roll that melts the toner image, the calorific value changes according to the supplied power, and
A first element having a resistance value that varies depending on temperature, disposed at a position that is separated from the heat roll to be measured and receives radiant heat from the heat roll;
A second element having a resistance value that varies depending on temperature, disposed at a position away from the heat roll and avoiding radiant heat from the heat roll;
A temperature measuring unit for determining a temperature of the heat roll based on a resistance value of the first element and a resistance value of the second element;
A power control unit that controls power supply to the heat roll according to the temperature determined by the temperature measurement unit,
The first element and the second element have a resistance value of the first element and a resistance value of the second element when both the first element and the second element are at the same temperature. An image forming apparatus, wherein the difference is an element having a minimum value at any temperature within a temperature measurement range of the second element.

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