JP2008111849A - Noncontact temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide noncontact temperature sensor which accurately can detect skin temperature of sensing object and also accurately can measure it in a short time. <P>SOLUTION: This noncontact temperature sensor includes a support 21 which has light guiding section for guiding infrared radiation entered from aperture 21a; a resin film 23 arranged on other end aperture on the light guiding section of the above support 21; a lid member 29 with space area for preparing space behind the above resin film 23 formed to be mounted on the support 21; a heat-sensitive element 25 for infrared light detection which is arranged on the space area side of the resin film 23 to sense infrared radiation entered from aperture 21a; and heat-sensitive elements 26 and 27 for temperature compensation which are arranged on surfaces of or inside the support 21 other than inside the space of the space area to detect temperature of the support 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a non-contact temperature sensor, and more specifically, in order to fix an unfixed toner image on a sheet in a fixing device such as a copying machine, the surface temperature of a rotating body such as a heating fixing roller of the fixing device. The present invention relates to a non-contact temperature sensor that detects non-contact.

  2. Description of the Related Art Conventionally, as a temperature sensor for a heat fixing roller of a copying machine, a contact type temperature sensor that detects a temperature by bringing a thermosensitive element into contact with the roller surface is mainly used. Although this type of contact-type temperature sensor has the advantage of being able to accurately detect the surface temperature of the heat-fixing roller, the contact portion of the heat-sensitive element is pressed against the surface of the heat-fixing roller at a constant pressure. In addition, there is a drawback that the surface of the heat fixing roller is damaged by the heat sensitive element.

  In addition, the contact member of the contact-type temperature sensor has high wear resistance that can withstand long-term use, and the pressure of the spring material that presses the thermal element is applied, so a material with a certain thickness or more is used. Must. For this reason, the heat capacity of the thermal element portion of the contact-type temperature sensor increases, and there is a drawback that desired thermal response characteristics cannot be obtained.

  As a temperature sensor that solves such a drawback, there is a non-contact type temperature detector. As a conventional example 1 of this type, there is a temperature sensor disclosed by the present applicant in Japanese Patent Application No. 3-27515. This non-contact temperature detector is mounted on an electrically insulating heat-resistant substrate having two lead portions formed of conductive foil and a small hole between the two lead portions of the heat-resistant substrate. A heat-sensitive element connected between the lead parts, at least a part of the heat-sensitive element and a vicinity of the lead part of the heat-resistant substrate, and a support body for attaching the heat-resistant substrate to the lower surface of the opening; It is composed of a thin-film shielding plate having a smaller heat capacity than the support attached to the upper surface of the opening. Since this temperature sensor can detect the temperature of the object to be detected in a non-contact manner and can reduce the heat capacity of the sensor, it is possible to obtain characteristics with excellent thermal responsiveness.

  As a conventional example 2, there is a non-contact type temperature sensor shown in FIG. In this temperature sensor, an optical system 3 composed of a Fresnel lens is provided at the tip of a cylindrical non-contact temperature sensor body 10, and the temperature of the infrared detector 1 composed of a thermopile and the temperature of the infrared detector 1 is measured in the body. A temperature sensor 2 for measuring and a temperature sensor 4 for measuring the temperature of the optical system 3 are provided. The temperature sensors 2 and 4 are posistors.

FIG. 14 shows a signal processing circuit of the non-contact temperature sensor of FIG. The output from the infrared detector 1 is amplified by the amplification unit 6 via the polarity switching unit 5, converted into a digital signal by the A / D conversion unit 9 comprising a double integration circuit, and then processed by the microcomputer 11. ing. A constant current is supplied from the constant current source 8 to the temperature sensors 2 and 4, and signals from the temperature sensors 2 and 4 are switched by the switching unit 7 and converted into digital signals by the A / D conversion unit 9, and then the microcomputer 11 is processed. The temperature sensor 2 detects the temperature of the infrared detector 1, and the temperature sensor 4 detects the temperature of the optical system 3. It is a signal processing circuit of a non-contact type temperature sensor provided with temperature compensation means for compensating for an error caused by the optical system based on a temperature difference measured by these temperature sensors.
Japanese Utility Model Publication No. 4-122341

  The non-contact temperature sensor of Conventional Example 1 is sufficient if the distance between the heat-sensitive surface of the heat-sensitive element on the heat-resistant substrate and the roller surface is not set to about 0.5 mm when used in a heat fixing roller of a copying machine. There is a drawback that sensitivity cannot be obtained. Such distance setting is extremely difficult, and when mounted close to the heat fixing roller, there is a problem that the temperature sensor is broken when a paper jam occurs in the copying machine.

  In the non-contact type temperature sensor of Conventional Example 2 in FIG. 13, the optical system 3 is provided on the infrared incident surface, and there is a defect that the toner tends to adhere to the optical system 3 when mounted on the heat fixing roller. There is a drawback in that the toner adheres to the surface of the system 3 and the amount of transmitted infrared rays changes due to contamination. If toner or dust adheres to the surface of the optical system 3, such as an infrared filter, and the contamination of the surface of the optical system 3 proceeds, the detection output will be reduced and accurate temperature detection will not be possible. For applications that must be done, there was a drawback that they could not be used. Therefore, in the non-contact type temperature sensor, since the radiation law of infrared rays from the object to be detected changes due to the change in the ambient temperature, another temperature compensation temperature sensor for measuring the ambient temperature is attached, and the ambient temperature A change is detected. Using the signal processing circuit shown in FIG. 14, a complicated numerical calculation such as switching of the function table according to the change of the ambient temperature is performed by the microcomputer 11 together with the change of the transmission amount due to the contamination of the optical system 3. There was a need to do.

  Further, there is a method using a thermistor bolometer, a thermopile, a pyroelectric sensor or the like known as an infrared detector. However, the thermistor bolometer and thermopile have the disadvantages of low sensitivity and high cost. In addition, the pyroelectric sensor has a problem in reliability because it requires a chopper, and there are technical problems such as temperature compensation in order to use it under a high temperature such as a fixing device. difficult.

  The present invention has been made in view of the problems as described above, and can detect the surface temperature of the detected object accurately and can accurately measure the surface temperature of the detected object in a short time. The object is to provide a temperature sensor.

  The invention according to claim 1, which has been made in order to solve the above-described problem, is arranged in a holding body having a light guide portion that guides infrared light incident from an opening portion, and the other end opening portion of the light guide portion of the holding body. A resin film, a lid member formed with a space for providing a space behind the resin film and attached to the holding body, and an infrared ray that is disposed on the space part side of the resin film and is incident from the opening. It comprises a heat-sensitive element for detecting infrared rays to be detected, and a temperature-compensating heat-sensitive element that is arranged on the surface or inside of the holding body other than in the space and detects the temperature of the holding body.

  The invention according to claim 2, which has been made to solve the above problems, includes a holder having an infrared incident opening, a resin film disposed on the back side of the opening of the holder, and a space behind the resin film. A lid member that is formed on the holding body and is disposed on the space portion side of the resin film and that detects infrared rays incident from the opening, and the holding member. A temperature-compensating thermosensitive element that is disposed on the surface of the body and detects the temperature of the holding body, and the lid member further includes a recess for providing a space behind the temperature-compensating thermosensitive element. The infrared detecting thermal element and the temperature compensating thermal element are housed so as to be closed in the space of the space and the space of the recess, respectively.

  The invention according to claim 3, which has been made to solve the above problem, is the non-contact temperature sensor according to claim 2, wherein the size of the space of the concave portion is smaller than the size of the space of the space portion. It is characterized by.

  According to a fourth aspect of the present invention, there is provided the non-contact temperature sensor according to the second or third aspect, wherein the infrared detecting thermal element and the temperature compensating thermal element are the same as the resin film. It is arranged on a plane.

  Embodiments of a non-contact temperature sensor according to the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing an embodiment of the non-contact temperature sensor of the present invention, FIG. 2 is a perspective view showing an example in which the non-contact temperature sensor is mounted on a heat fixing roller, and FIG. It is XY sectional drawing of the non-contact temperature sensor of FIG.

  In FIG. 1, the non-contact temperature sensor 20 includes a holding body 21 formed of a light guide portion having a rectangular cross section, a resin film 23 provided with a heat sensitive element, and a lid member 29. The holding body 21 has one end of the holding body 21 that is an opening 21a through which infrared rays are incident and the other end that is an opening 21b. The inside of the holding body 21 is a light guide that guides infrared rays. The opening 21 b is covered with the resin film 23 and closed with a lid member 29. On the back surface of the resin film 23 (the surface opposite to the infrared incident surface), an infrared detecting thermal element 25 is provided. As shown in FIG. 3, a space 30 is formed between the resin film 23 and the lid member 29. The holding body 21 is provided with mounting ears 22 having mounting holes 22a in order to mount the non-contact temperature sensor 20 close to the detected body. The thermosensitive elements 25 to 27 use thin film thermistors, but are not limited thereto.

  The holding body 21 is made of a metal having a high thermal conductivity and a low thermal emissivity, such as aluminum, and its inner surface is a reflecting surface that reflects infrared rays. The reflecting surface may be polished to increase the infrared reflectance as necessary, or the holding body 21 itself is formed of a resin, and a metal layer that actively reflects infrared rays on the inner surface thereof. It may be a reflective surface. Furthermore, you may provide the infrared rays absorption film which absorbs infrared rays in the whole inner surface or at least one part of a light guide part. By providing the infrared absorption film, even if the toner scattered around the fixing device adheres to the inner surface of the holding body 21, the heat emissivity of the toner is close to 1, and the output signal of the infrared sensor is Has little effect.

  The infrared absorbing film is formed by a method such as coating plastic, rubber or the like on the inner surface or / and outer surface of the light guide. For example, these materials are preferably black body absorbing films having an emissivity of 0.94 or more. As other materials, even if at least a part of the inner surface of the holding body 21 is anodized or anodized, the same effect as the infrared absorption film can be obtained.

  Furthermore, the shape of the opening 21a of the holding body 21 is appropriately selected according to various conditions such as the size and shape of the detected body and the distance from the temperature sensor. For example, when measuring the surface temperature of the heat fixing roller, since the heat fixing roller is a horizontally long heating element, the opening 21a of the holding body 21 has a horizontally long shape or an elliptical shape extending along the axial direction of the roller. To do. By setting it as such a shape, the heat collection effect of the holding body 21 becomes favorable, and detection sensitivity and thermal responsiveness can be improved.

  In addition, when the non-contact temperature sensor is installed further away from the detected body, the infrared incident opening 21a is further away from the detected body surface, so if an infrared absorption film is formed on the inner surface of the light guide section, The heat radiated from the background portion other than the detection target is incident on the light guide and absorbed by the infrared absorption film on the inner surface, and thus does not reach the resin film 23. Therefore, the detection temperature error due to the heat radiation from the background portion can be eliminated, and only the heat radiated from the detected object can be accurately detected. Further, the same effect can be obtained by resin-molding the light guide part instead of providing the infrared absorbing film on the inner surface of the light guide part.

  Next, the resin film 23 will be described in detail. The resin film 23 has a wiring pattern 24 formed on one surface thereof, and the first and second temperature compensating heat sensitive elements arranged in close proximity to the infrared detecting thermal element 25. Elements 26 and 27 are electrically connected to the wiring pattern 24. An external lead terminal 28 is formed at the end of the wiring pattern 24. The infrared detecting thermal element 25 is located on the substantially central surface of the resin film 23 and is disposed on the surface of the resin film 23 opposite to the infrared incident side. The first and second temperature compensating thermal elements 26 and 27 are formed near the end of the resin film 23. By attaching the resin film 23 so as to be in close contact with the opening 21b and attaching the lid member 29, the infrared detecting thermal element 25 is disposed at substantially the center of the opening 21b, and the first and second temperature compensating elements are provided. The thermal elements 26 and 27 are disposed on the side surface of the holding body 21. The first and second temperature compensating thermal elements 26 and 27 detect the ambient temperature. The temperature compensating thermosensitive elements 26 and 27 detect the temperature of the holding body 21 as a structure arranged in the thick part of the holding body.

  The resin film 23 is made of a resin made of a polymer material such as Teflon (registered trademark), silicon, polyimide, polyester, polyethylene, polycarbonate, PPS (polyphenylene sulfide), and any other material that absorbs infrared light. A material may be used. Furthermore, carbon black or an inorganic pigment (one or more of chrome yellow, petal, titanium white, ultramarine) is mixed and dispersed in these resins, and a material that can absorb infrared rays of almost all wavelengths is used. Further, by providing an infrared reflecting film on the back surface of the resin film 23 or the space 30 behind the resin film 23, the detection sensitivity can be further improved by reflecting the heat radiated from the resin film 23.

  On the other hand, the non-contact temperature sensor of the present invention is mainly assumed to be mounted on a fixing device such as a compounding machine, and since there is heat radiation from the outer peripheral members of the non-contact temperature sensor, This thermal radiation tends to cause a temperature detection error. For this purpose, a structure in which infrared rays are reflected by a method such as plating the outer surface of a non-contact temperature sensor holding body or lid member, mirror finishing, or attaching an infrared reflecting material such as a thin film or foil In addition, the detection sensitivity can be further improved by minimizing the influence of the outside world.

  FIG. 2 shows an example of mounting the non-contact temperature sensor 20 shown in FIG. As shown in the figure, the heat-fixing roller 12 is attached to an L-shaped metal fitting 13 provided in the axial direction. An opening 15 is formed in the L-shaped metal fitting 13, and is fixed to the L-shaped metal fitting 13 with a bolt 14 so that the opening 21 a of the non-contact temperature sensor 20 coincides with the opening 15. The opening 21 a of the non-contact temperature sensor 20 has a horizontally long opening along the axial direction of the heat fixing roller 12. As described above, the non-contact temperature sensor 20 has the horizontally long opening 21a, so that the heat radiated from the heat fixing roller 12 can be efficiently captured. Further, the infrared light incident from the opening 21 a is reflected by the inner surface of the holding body 21 and reaches the surface of the resin film 23 of the opening 21 b and the thermal element 25 for infrared detection. The outputs of the infrared detecting thermal element 25 and the temperature compensating thermal elements 26 and 27 are input to the detection circuit D.

  Next, the detection circuit of the non-contact temperature sensor will be described with reference to FIGS. In FIG. 4A, the temperature compensating thermal element 27 and the infrared detecting thermal element 25 are connected in series between the power supply terminal V and the ground, and the temperature compensating thermal element 26 and the resistor 31 are similarly connected to the power supply terminal V. Connected in series between ground. The connection point A between the temperature compensation thermal element 27 and the infrared detection thermal element 25 and the connection point B between the temperature compensation thermal element 26 and the resistor 31 are connected to the input terminal of the operational amplifier 32, and the output is Obtained from the output terminal 33. These circuit elements constitute a bridge circuit.

  Explaining with reference to the non-contact temperature sensor, infrared rays emitted from the surface of the heat fixing roller are incident from the opening 21a of the non-contact temperature sensor 20, reach the resin film 23 through the light guide, The infrared energy is absorbed by the resin film 23 and converted to heat, and is transmitted to the infrared detecting thermal element 25, and the temperature of the infrared detecting thermal element 25 increases. At this time, since the resin film 23 also receives the infrared rays at the portion corresponding to the opening area, the infrared energy is thermally converted, and the temperature of the resin film 23 rises and is effectively transmitted to the thermal element 25 for detecting infrared rays. The infrared detecting thermal element 25 and the temperature compensating thermal element 26 are thermal elements having at least substantially equal temperature characteristics. When the resistance value of the infrared detecting thermal element 25 is changed by infrared rays from the detection object, the potential at the connection point A changes. At the same time, the temperature of the holding body 21 also rises due to the radiant heat from the body to be detected and the ambient ambient temperature, so that the resistance values of the temperature compensating thermal elements 26 and 27 placed on the outer surface of the holding body 21 also increase the temperature of the holding body 21. The corresponding resistance value change is received. Since the temperature compensating thermosensitive elements 26 and 27 have substantially the same temperature characteristics, the potential at the connection point A can detect only a temperature change due to infrared rays from the detection target. Of course, the detection circuit shown in FIG.

  In the detection circuit of FIG. 4C, the infrared detecting thermal element 25 and the temperature compensating thermal element 26 are connected in series and connected to the constant current source 34. The connection point A between the constant current source 34 and the infrared detection thermal element 25 and the connection point B between the infrared detection thermal element 25 and the temperature compensation thermal element 26 are connected to the input terminal of the operational amplifier 32, respectively. 33. The output of the connection point A is output by adding the output of the connection point B of the infrared detecting thermal element 25 and the temperature compensating thermal element 26. Therefore, in this constant current method, the influence of the ambient atmosphere is offset on the output side of the operational amplifier 32 by adding / subtracting the output of the connection point A and the output of the temperature compensating thermal element 26 at the connection point B. There is an advantage that an output can be obtained and the circuit configuration can be simplified as compared with other circuit systems.

  FIG. 5 shows actual temperature control using a heat fixing roller as an example. Since the temperature of the holding body 21 fluctuates due to heat radiated from the detected object and convection around the sensor, FIG. When the potential at the connection point A of the detection circuit is proportional to the temperature fluctuation of the holding body 21 and the control output (control temperature) changes with time as shown by the curve a in FIG. There is. In the present invention, since the second temperature compensating thermosensitive element 26 is arranged in the vicinity of the first temperature compensating thermosensitive element 27 and the temperature around the sensor rises, the surface temperature of the holding body 21 also rises. In addition, the output of the bridge circuit composed of the second temperature compensating thermosensitive element 26 and the resistor 31, that is, the potential at the connection point B rises with time as shown by the curve b in FIG. This causes the control temperature to fluctuate as shown by curve a. In the present invention, a change in the ambient atmosphere is detected by the second temperature compensation thermal element 26, and the output is added to the output composed of the first temperature compensation thermal element 27 and the infrared detection thermal element 25. By canceling the influence of the surrounding atmosphere, the infrared output of the detection target can be accurately detected as shown by the curve c in FIG.

  Next, a specific example of the detection circuit for the non-contact temperature sensor will be described with reference to the detection circuits of FIGS. In FIG. 6, a temperature compensation thermal element 27 and an infrared detection thermal element 25 are connected in series between a power supply terminal V and the ground, and a resistor R1, a variable resistor R2, and a resistor R3 are connected in series to form a reference voltage source circuit 37. The temperature compensation thermosensitive element 26 and the resistor 31 are connected in series between the power supply terminal V and the ground, and the reference voltage source circuit 38 is connected in series with the resistor R1, the variable resistor R2, and the resistor R3. Has been. The temperature compensating thermosensitive elements 26 and 27 are arranged close to each other.

  In the inverting amplifier A1, a resistor R4 is connected between the inverting input terminal and the connection point A, a resistor R6 is connected between the inverting input terminal and the output terminal, and between the variable resistor R2 (non-inverting input terminal) and the non-inverting terminal. A resistor R4 is connected, and a resistor R5 is connected between the non-inverting terminal and the ground. The output terminal of the inverting amplifier A1 is connected to the non-inverting input terminal of the operational amplifier A3 via the resistor R7. In the inverting amplifier A2, a resistor R4 is connected between the inverting input terminal and the connection point B, a resistor R6 is connected between the inverting input terminal and the output terminal, and a resistor R4 is connected between the variable resistor R2 and the non-inverting input terminal. And a resistor R5 is connected between the non-inverting input terminal and the ground. Resistors R5 and R6 have the same resistance value. The output terminal of the inverting amplifier A2 is connected to the inverting input terminal of the operational amplifier A3 via the resistor R9. The operational amplifier A3 has a resistor R10 connected between the inverting input terminal and the output terminal, and a resistor R8 connected between the non-inverting input terminal and the ground. By adding the outputs of the output points PA and PB by the operational amplifier A3, an output of the surface temperature ΔT of the heat-fixing roller 12 that cancels out the influence of the ambient temperature can be obtained from the output terminal PC.

  A control output signal can be extracted from the output signal ΔT by performing a comparison operation by adding the operational amplifier A4 shown in FIG. This control output signal is used for temperature control of the fixing device. In FIG. 7, point E of the temperature setting circuit composed of a series circuit of resistors R12, R13 and variable resistor VR connected to the reference voltage source 39 is connected to the non-inverting input terminal of the operational amplifier A4, and the output of the operational amplifier A3. Connect the terminal to the inverting input terminal through a resistor. The output signal ΔT is input to the inverting input terminal of the operational amplifier A4, the VR of the temperature setting circuit is adjusted to set the desired temperature, the potential at the point E is compared with the output signal ΔT, and the output signal is output. Thus, a control signal at an arbitrary set temperature can be taken out by controlling the solid state relay S1.

  Of course, as shown in FIG. 8, the surface temperature of the detected object can also be detected by a digital temperature control circuit using a microcomputer. In FIG. 8, the output voltage (ΔT ′ + Δt) and Δt at points C and D of the series circuit of the infrared detecting thermal element 25 and the temperature compensating thermal element 26 connected to the constant current source 40 are represented by resistors R1 and R2. Are input to the A / D converters 46 and 47, respectively, and digitized (ΔT ′ + Δt) and Δt are obtained. The digitized output Δt from the A / D converter 47 becomes the temperature compensation output. The relationship between ΔT ′ and Δt is input to the microcomputer CPU, ΔT ′ is calculated by the subtracting means 48 and input to the condition determining means 49. As shown in FIG. 8, the condition determining means 49 determines the relationship between ΔT ′ and the set temperature Ta with reference to a pre-stored data table 50, determines “1”, “0”, and solids Control the state relay S1. In the case of “1”, the heater is energized. In the case of “0”, the energization to the heater is cut off. By such control, the surface temperature of the heat fixing roller is set to a predetermined temperature.

  Further, the temperature detection circuit of FIG. 8 uses the detection circuit of FIG. 4C, but may be the detection circuit of FIGS. 4A and 4B. In the case of FIG. 4A, a temperature compensated output is obtained, and this output is input to the microcomputer CPU via the A / D converter, and the surface temperature is detected by the data table 50. In FIG. 4B, the surface temperature of the detection object can be detected by performing the same process as the temperature detection circuit using the microcomputer CPU of FIG.

Incidentally, the principle of operation of the non-contact temperature sensor of the present invention will be described with reference to FIG. The output voltage of the operational amplifier A3 represents the surface temperature ΔT of the heat fixing roller 12, and the operation principle will be described. The temperature (case temperature) t ₁ of the holding body 21 is expressed as t ₁ = Δf (T) + Δf (t). However, Δf (T) indicates a change in temperature due to the heat-fixing roller 12, and Δf (t) indicates a change in ambient temperature.

Since the ambient temperature t ₁ ′ of the infrared detecting thermal element 25 is substantially equal to the case temperature t ₁ , it is expressed as t ₁ ′ = t ₁ + a. a is a factor other than the case temperature t ₁ . Therefore, if a temperature change due to heat radiation from the heat fixing roller 12 is detected by the infrared detecting thermal element 25 and the temperature change is ΔT, ΔT is expressed as a function of f (IR) = ΔT. The infrared detecting thermal element 25 is influenced by the ambient temperature t ₁ ′. When the reference voltages of the reference voltage source circuits 37 and 38 are represented by the relationship of the resistance components of the reference voltage, there is a relationship of ΔR≈ΔR ′ + b. The temperature compensating thermosensitive elements 26 and 27 are thermally coupled, and have a relationship of f (Ref1) = f (Ref2) = t ₁ (= t ₁ ′ −a).

When the output of the inverting amplifier A1 is regarded as a temperature, the output of the output terminal is expressed as PA = ΔT + t ₁ ′. Similarly, the output at the output terminal of the inverting amplifier A2 is expressed as PB = t ₁ . Therefore, the output terminal of the operational amplifier A3 of the detection circuit of FIG. 6 is expressed as PC = ΔT + a≈ΔT. As described above, in the present invention, by using the non-contact temperature sensor of the present embodiment, the temperature can be detected without performing a calculation process using a complicated function.

  Next, another embodiment of the non-contact temperature sensor of FIG. 1 will be described with reference to FIG. The mounting structure of the resin film 23 is not limited to the embodiment of FIG. 1, and may be the form shown in FIGS. In FIG. 6A, the temperature compensating thermal elements 26 and 27 are arranged on both outer surfaces of the holding body, respectively, and in FIG. 5B, the temperature compensating thermal element 26 and 27 are arranged on one outer surface of the holding body. Has been. Further, in FIG. 2C, temperature compensating heat sensitive elements 26 and 27 are arranged behind the space where the infrared detecting heat sensitive element 25 is accommodated. Furthermore, the resin film 23 provided with the thermosensitive element is formed with a slit in the rear portion of the holder of the light guide unit that is open at one end and closed at the other end, and the resin film 23 is inserted into the slit to You may form a heat sensitive part in the position away from the opening part.

  Further, the detection sensitivity may be improved by making the holder of the light guide part of the non-contact temperature sensor into a tapered shape and condensing the infrared rays incident from the detected object into the light guide part on the heat sensitive element part (illustration shown). None).

  The first and second temperature compensating thermosensitive elements 26 and 27 may be arranged at positions on the holding body such that the temperatures of the two thermosensitive elements are substantially equal to each other, and are described in this embodiment. As described above, it is not always necessary to dispose the two temperature compensating thermosensitive elements close to each other.

  Next, another embodiment of the non-contact temperature sensor of the present invention will be described with reference to FIG. 2A is an exploded perspective view, FIG. 2B is a cross-sectional view, and FIG. 2C is a perspective view. The non-contact temperature sensor of FIG. 11 is a temperature sensor that detects the temperature of the detected object in a non-contact manner. The non-contact temperature sensor 39 is a wiring in which the plate-like holding body 40 in which the opening 41 is formed, the infrared detecting thermal element 25 and the first and second temperature compensating thermal elements 26 and 27 are electrically connected. It is composed of a resin film 23 on which a pattern is formed and a lid member 42. The lid member 42 is formed with a space 43 for providing a space behind the infrared detecting thermal element 25 and a recess 44 for providing a space behind the temperature compensating thermal elements 26 and 27. When the resin film 23 is fixed and held by the lid member 42, the infrared detecting thermal element 25 is accommodated in the space 43 formed in the lid member 42, and the temperature compensating thermal elements 26, 27 are stored in the recess 44. Is stored.

  The resin film 23 is disposed on the back surface (the surface opposite to the infrared incident surface) of the holding body 40 so as to cover the opening 41. Infrared rays enter through the opening 41 formed in the holding body 40 and are applied to the resin film exposed in the opening 41. As described above, the resin film 23 uses a material that absorbs infrared rays, such as polyester and polyimide resin, or absorbs infrared rays of almost all wavelengths by dispersing carbon black or an inorganic pigment in these resins. The resulting material is used. On the resin film 23, the infrared detecting thermal element 25 and the first and second temperature compensating thermal elements 26 and 27 are bonded and fixed to a wiring pattern formed on the surface opposite to the surface on which the infrared rays are incident. . The infrared detecting thermal element 25 is disposed at a substantially central portion of the opening 41 of the holding body 40, and the first and second temperature compensating thermal elements 26 and 27 are provided when the lid member 42 is attached to the holding body 40. In addition, the resin film 23 is attached to the surface of the holding body 40 so as to be accommodated in the recess 44. These thermosensitive elements are accommodated so as to be closed in the space. The first and second temperature compensating thermal elements 26 and 27 are arranged to detect the temperature of the holding body 40 including the lid member 42.

  Further, the first and second temperature compensating thermosensitive elements 26 and 27 are arranged as close as possible so that the ambient ambient temperature in the same place can be detected, and an external lead terminal 28 is formed at the end of the wiring pattern. Has been. As these thermal elements, a thin film thermistor is used, and is electrically connected to a wiring pattern formed on the resin film 23. The thermal element is not limited to a thin film thermistor, and may be another semiconductor temperature sensor.

  In the present embodiment, the temperature compensation thermal element is described as being arranged together with the infrared detection thermal element on the resin film. However, the temperature compensation thermal element does not necessarily have to be placed on the same resin film. Alternatively, as long as the temperature of the holding body can be detected, it may be arranged alone on the holding body surface or inside the holding body.

  The material of the holder 40 is made of a metal having a high thermal conductivity such as aluminum and a low thermal emissivity. Further, instead of forming the holding body 40 from a metal, a holding body having a structure in which the holding body 40 is formed from a resin and a metal layer is formed on the surface thereof may be used. The shape of the opening 41 of the holding body 40 is appropriately selected depending on conditions such as the size and shape of the detection object, the distance from the sensor, and the like. For example, when measuring the surface temperature of a heat fixing roller of a copying machine or the like, the opening 41 of the holding body has a horizontally long shape or an elliptical shape that extends in the axial direction of the roller, thereby improving detection sensitivity and thermal response. Can do. When the roller diameter is small, in order to reduce the viewing angle of the opening 41, the width of the opening perpendicular to the roller axis is reduced and the length of the opening in the axial direction is increased.

  Since the detection output of the non-contact temperature sensor in FIG. 11 is arranged close to the detection target, it is substantially the same as the temperature sensor including the holding body having the light guide unit of the above embodiment, but depending on the installation conditions Although it may decrease by about 10 to 15%, it is a level that can be used sufficiently. Since the detection sensitivity of this temperature sensor depends on the distance to the object to be detected, when there is not enough space for installing the non-contact temperature sensor of FIG. 1 of the present invention, the non-contact temperature sensor of FIG. The temperature of the detected object can be accurately detected by installing it close to the detected object.

  FIG. 12 shows a non-contact temperature sensor according to another embodiment of the present invention. It is the non-contact temperature sensor 39 of the structure which added the elliptical column-shaped light guide part 45 resin-molded to the non-contact temperature sensor shown in FIG. The non-contact temperature sensor 39 of the present embodiment is the same as the configuration of FIG. 11 except that a light guide portion 45 made of resin is attached to the opening 41 shown in FIG. The non-contact temperature sensor in FIG. 12 can accurately detect only the temperature change of the detected object because the influence of infrared rays entering from the opening 41a of the light guide unit 45 from the part other than the detected object can be ignored. It becomes possible.

  Furthermore, the shape of the lid member 42 is not limited to that shown in FIG. The same applies to the non-contact temperature sensor of FIG. In the above embodiment, the external lead terminal may be connected to the detection circuit by connecting a cord by a known method.

  Of course, in the present embodiment, the temperature detection of the heat fixing roller has been described. However, the present invention is not limited to this, and can be widely used for non-contact temperature detection.

It is the disassembled perspective view which showed one Embodiment of the non-contact temperature sensor of this invention. It is the perspective view which mounted the non-contact temperature sensor of the present invention on the heat fixing roller. It is sectional drawing along the XY line of the non-contact temperature sensor of FIG. (A)-(c) is a circuit diagram of the detection circuit for non-contact temperature sensors. It is a figure for demonstrating the temperature control by the non-contact temperature sensor by this invention. It is a circuit diagram which shows the other Example of the detection circuit for non-contact temperature sensors. It is a circuit diagram which shows the other Example of the detection circuit for non-contact temperature sensors. It is a circuit diagram which shows the other Example of the detection circuit for non-contact temperature sensors. It is a figure for demonstrating operation | movement of the non-contact temperature sensor of this invention. It is sectional drawing which shows other embodiment of the non-contact temperature sensor of this invention. It is a figure which shows other embodiment of the non-contact temperature sensor of this invention. It is a figure which shows other embodiment of the non-contact temperature sensor of this invention. It is sectional drawing which shows an example of the conventional non-contact temperature sensor. It is a circuit diagram which shows the detection circuit of the conventional non-contact temperature sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Holding body 21a, 21b Opening part 22 Mounting ear part 23 Resin film 24 Wiring pattern 25 Infrared detection thermal element 26, 27 Temperature compensation thermal element 28 External extraction terminal 29 Lid member 40 Holding body 41, 41a Opening part 42 Lid member Reference Signs List 43 Space 44 Recess 45 Light Guide A1, A2 Inverting Amplifier A3, A4 Operational Amplifier D Detection Circuit CPU Microcomputer 21 Holding Body 21a, 21b Opening 22 Mounting Ear 23 Resin Film 24 Wiring Pattern 25 Infrared Detection Thermal Element 26 , 27 Temperature-sensitive thermal element 28 External lead terminal 29 Lid member 40 Holder 41, 41a Opening 42 Lid member 43 Space 44 Recess 45 Light guide A1, A2 Inverting amplifier A3, A4 Operational amplifier D Detection circuit CPU Microcomputer

Claims (4)

  A holding body having a light guide for guiding infrared light incident from the opening, a resin film disposed in the other end opening of the light guide of the holding body, and a space for providing a space behind the resin film A lid member that is formed and attached to the holding body, is arranged on the space part side of the resin film, and is an infrared detection thermal element that detects infrared rays incident from the opening, and other than in the space of the space part A non-contact temperature sensor comprising a temperature-compensating thermal element that is disposed on or inside the holding body and detects the temperature of the holding body.   A holding member having an infrared incident opening, a resin film disposed on the back side of the opening of the holding body, and a lid member formed with a space for providing a space behind the resin film and attached to the holding body And an infrared detecting thermal element that is disposed on the space portion side of the resin film and detects infrared rays incident from the opening, and a temperature compensation element that is disposed on the surface of the holding body and detects the temperature of the holding body. The lid member is further formed with a recess for providing a space behind the temperature compensating thermal element, the infrared detecting thermal element and the temperature compensating thermal element are respectively The non-contact temperature sensor is housed so as to be closed in the space of the space and in the space of the recess. The non-contact temperature sensor according to claim 2,
The non-contact temperature sensor, wherein the size of the space of the recess is smaller than the size of the space of the space. The non-contact temperature sensor according to claim 2 or 3,
The non-contact temperature sensor, wherein the infrared detecting thermal element and the temperature compensating thermal element are arranged on the same plane of the resin film.

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