Non-contact temperature sensor

Abstract

The present invention provides a non-contact temperature sensor capable of improving thermal responsiveness and temperature measurement accuracy, and provides a temperature sensor capable of ensuring reliability and improving thermal responsiveness, and a device provided with the temperature sensor. A non-contact temperature sensor (1) is provided with a holder (2), a lead part (3) held by the holder, and a temperature-sensitive element (10) electrically connected to the lead part (3), and is characterized by being provided with a glass substrate (11) made of a glass material on which the temperature-sensitive element (10) is formed, and the glass substrate (11) does not undergo phase change in a use temperature range.

Description

Technical Field

[0001] This invention relates to a non-contact temperature sensor suitable for detecting surface temperature without contacting the surface of the object being tested. Background Technology

[0002] In the past, temperature sensors have been incorporated into electronic devices such as office automation equipment like copiers and printers, information and communication equipment like mobile communication terminals and personal computers, imaging equipment, consumer equipment, and automotive electrical equipment in order to detect the temperature of the object being tested (see Patent Documents 1 to 4).

[0003] For example, a temperature sensor is used to detect the surface temperature of a sample consisting of a rotating or stationary heating roller used in the fixing unit of a copier, printer, etc., in a non-contact manner, and to control the temperature of the heating roller. Specifically, the surface temperature of the sample is detected by a temperature-sensing element formed on a ceramic substrate such as an alumina substrate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5707081

[0007] Patent Document 2: Japanese Patent No. 6502588

[0008] Patent Document 3: Japanese Patent No. 6842600

[0009] Patent Document 4: Japanese Patent No. 6282526 Summary of the Invention

[0010] In the case of existing temperature sensors as described above, the temperature sensor does not contact the surface of the object being measured, thus detecting the surface temperature in a non-contact manner. Therefore, there is a problem of poor thermal response and temperature measurement accuracy of the temperature sensor, and it is desirable to improve thermal response and temperature measurement accuracy.

[0011] The present invention was made in view of the above-mentioned problems, and its object is to provide a non-contact temperature sensor that can achieve improved thermal responsiveness and temperature measurement accuracy.

[0012] The non-contact temperature sensor of this embodiment has a bracket, a lead portion held in the bracket, and a temperature sensing element electrically connected to the lead portion. The non-contact temperature sensor is characterized by having a glass substrate, which is made of a glass material on which the temperature sensing element is formed, and the glass substrate does not undergo a phase change within the operating temperature range.

[0013] According to the invention, in non-contact temperature sensors, the glass substrate is extremely thin, has a small heat capacity, and good infrared absorption rate, which can improve thermal responsiveness and temperature measurement accuracy.

[0014] (Invention effect)

[0015] According to embodiments of the present invention, a non-contact temperature sensor that can achieve improved thermal responsiveness and temperature measurement accuracy can be provided. Attached Figure Description

[0016] Figure 1 This is a top view showing a non-contact temperature sensor according to the first embodiment of the present invention.

[0017] Figure 2 This is a top view showing the non-contact temperature sensor according to the second embodiment.

[0018] Figure 3 This is a top view showing the non-contact temperature sensor according to the third embodiment.

[0019] Figure 4 This is a top view showing the non-contact temperature sensor according to the fourth embodiment.

[0020] Figure 5 This is a top view showing the non-contact temperature sensor according to the fifth embodiment.

[0021] Figure 6 This is a top view showing the non-contact temperature sensor according to the sixth embodiment.

[0022] Figure 7 This is a structural diagram illustrating the temperature sensing element in this invention.

[0023] Figure 8 This is a top view showing the connection method between the temperature sensing element and the lead wire in this invention.

[0024] Figure 9 This is a top view showing the connection method between the temperature sensing element and the lead wire.

[0025] Figure 10 This is also a top view showing the connection method between the temperature sensing element and the lead wire.

[0026] Figure 11 This is a table showing the evaluation of the heat capacity of the glass substrate of this embodiment and the alumina substrate as a comparative example.

[0027] Figure 12 This is a chart that represents an evaluation of the infrared transmittance of the glass substrate.

[0028] Figure 13 This is a table that represents an evaluation of the performance of the glass substrate.

[0029] Figure 14 This is an illustrative diagram schematically showing the installation state of a non-contact temperature sensor according to an embodiment of the present invention.

[0030] Figure 15 This is an illustrative diagram showing the installation status of the non-contact temperature sensor.

[0031] Figure 16 This is a table that represents the evaluation of different performance based on the installation status of non-contact temperature sensors.

[0032] (Symbol Explanation)

[0033] 1: Non-contact temperature sensor

[0034] 2: Bracket

[0035] 3: Lead wire section (lead wire frame)

[0036] 10: Temperature sensing element

[0037] 11: Insulating substrate (glass substrate)

[0038] 12: Electrical connection part

[0039] 12a, 12b: Electrode layers

[0040] 13: Protective film

[0041] 20: Heating roller

[0042] 21: Opening

[0043] 22: External lead wire

[0044] 23: Insulation Covering Part

[0045] 24: Lead wire Detailed Implementation

[0046] The following is for reference Figures 1 to 10 The non-contact temperature sensor according to an embodiment of the present invention will be described. It should be noted that, for ease of explanation, the scales of the components in the figures have been appropriately altered to make each component a recognizable size. Furthermore, identical or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted.

[0047] (First Implementation)

[0048] Reference Figure 1 The first embodiment will be described. Figure 1 This is a top view showing a non-contact temperature sensor.

[0049] The non-contact temperature sensor 1 includes a bracket 2, a lead frame 3 as a lead part, and a temperature sensing element 10.

[0050] The bracket 2 is formed from an insulating resin material, such as PPS (polyphenylene sulfide), into a generally rectangular parallelepiped shape, with a rectangular opening 21 at its approximately central portion, forming a frame shape. Furthermore, a hook hole 21a is formed at one end along the long side of the bracket 2, and a threaded hole 21b is formed at the other end. These hook holes 21a and threaded holes 21b are used, for example, when mounting a non-contact temperature sensor 1 to a fixing device. Furthermore, a pair of grooves are formed at the other end, and a pair of external leads 22 are disposed in these grooves. Specifically, the external leads 22 are leads that are insulated.

[0051] The lead frame 3, which serves as the lead portion, is fixed and held on the bracket 2 by insert molding. The lead frame 3 is an elastic body formed by means of chemical etching, stamping, etc., and is, for example, a narrow sheet-shaped metal plate formed of constantan material.

[0052] The temperature sensing element 10 is a thermistor element, specifically a thin-film thermistor formed on the insulating substrate 11, which will be described in detail later. The temperature sensing element 10 is electrically connected to the electrical connection portion 12 connected to the lead frame 3. The insulating substrate 11 is a glass substrate formed of glass material, and the thickness of the insulating substrate 11 is 200 μm or less, preferably 150 μm or less. With a thin glass substrate, cracking during substrate manufacturing can be suppressed compared to a ceramic substrate. It should be noted that a wiring pattern (not shown) for connecting the temperature sensing element 10 and the electrical connection portion 12 is appropriately formed on the insulating substrate 11.

[0053] The insulating substrate 11 is arranged in a bridging manner across the lead frame 3, and both ends of the insulating substrate 11 are connected to the electrical connection portion 12 connected to the lead frame 3 using solder or conductive paste. In this embodiment, the insulating substrate 11 is arranged, for example, in a direction perpendicular to the rotation direction of the heating roller used in the fixing device.

[0054] Furthermore, on the side opposite to the temperature sensing element 10, a heat-resistant insulating covering 23, such as a polyimide film, is adhered and provided to partially cover the opening 21. The insulating covering 23 insulates the temperature sensing element 10 and the exposed portion (electrical connection portion 12) of the lead frame 3, which serves as the lead portion. The insulating covering 23 is provided only in contact with the two opposite sides of the bracket 2. Therefore, heat loss is minimal. In this embodiment, the insulating covering 23 is provided to ensure electrical insulation and prevent dust adhesion.

[0055] It should be noted that the insulating cover can also clamp and cover the exposed portion (electrical connection portion 12) of the temperature sensing element 10 and the lead frame 3 (which serves as the lead portion) from both sides. Furthermore, the insulating cover preferably has infrared absorption capability. This helps to improve thermal response and temperature measurement accuracy. Specifically, it is ideal that the insulating cover is configured to absorb at least a portion of infrared radiation in the wavelength range of 1μm to 6μm. Moreover, since the insulating substrate 11, which serves as the glass substrate, is insulating, the insulating cover 23 can be omitted.

[0056] It should be noted that in subsequent embodiments, the structures of the bracket 2, the lead frame 3, and the temperature sensing element 10 are the same as in this embodiment. Therefore, the same or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted.

[0057] (Second Implementation)

[0058] Reference Figure 2 The second embodiment will be described. Figure 2 This is a top view showing a non-contact temperature sensor.

[0059] In this embodiment, the insulating substrate 11, which serves as the glass substrate, is disposed approximately at the center of the opening 21 of the support 2 along the long side direction of the lead frame 3. Furthermore, both ends of the insulating substrate 11 are electrically connected to the electrical connection portion 12. In this embodiment, for example, it is disposed in a direction parallel to the rotation direction of the heating roller used in the fixing apparatus.

[0060] (Third Implementation)

[0061] Reference Figure 3 The third embodiment will be described. Figure 3 This is a top view showing a non-contact temperature sensor.

[0062] In this embodiment, a temperature sensing element 10 is formed on a glass substrate and is connected to a lead wire 24. The lead wire 24 is integrally formed with the electrical connection portion 12 and is narrower than the electrical connection portion 12. The lead wire 24 is electrically connected to the temperature sensing element 10 by laser welding. It should be noted that although laser welding is preferred, soldering or conductive paste and wire bonding can also be used for connection. The temperature sensing element 10 is positioned approximately at the center of the opening 21 of the support 2, with the lead wire 24 arranged in a bridging manner and connected to the electrical connection portion 12.

[0063] (Fourth Implementation)

[0064] Reference Figure 4 The fourth embodiment will be described. Figure 4 This is a top view showing a non-contact temperature sensor.

[0065] In this embodiment, the lead wire 24 extends from the side of the external lead wire 22, and the temperature sensing element 10 is connected to the front end of the lead wire 24 by laser welding. It should be noted that although laser welding is preferred, soldering or conductive paste and wire bonding can also be used for connection. Similar to the third embodiment, the lead wire 24 is integrally formed with the electrical connection portion 12, and its width is narrower than that of the electrical connection portion 12.

[0066] The lead wire 24 extends along the long side of the lead wire frame 3, and the temperature sensing element 10 is located at the opening 21 of the bracket 2.

[0067] (Fifth Implementation)

[0068] Reference Figure 5 The fifth embodiment will be described. Figure 5 This is a top view showing a non-contact temperature sensor.

[0069] The basic structure of this embodiment is the same as that of the third embodiment (see reference). Figure 3 The difference lies in that the lead 24 and the electrical connection part 12 are separate components. The lead 24 is electrically connected to the temperature sensing element 10 and the electrical connection part 12 by laser welding. It should be noted that although laser welding is preferred, the connection can also be made by soldering or conductive paste and lead bonding.

[0070] (Sixth Implementation Method)

[0071] Reference Figure 6 The sixth embodiment will be described. Figure 6 This is a top view showing a non-contact temperature sensor.

[0072] The basic structure of this embodiment is the same as that of the fourth embodiment (see reference). Figure 4 The difference lies in that the lead 24 and the electrical connection part 12 are separate components. The lead 24 is electrically connected to the temperature sensing element 10 and the electrical connection part 12 by laser welding. It should be noted that although laser welding is preferred, the connection can also be made by soldering or conductive paste and lead bonding.

[0073] Next, refer to Figure 7 The temperature sensing element is explained. Figure 7 This is a structural diagram used to illustrate the temperature sensing element. The temperature sensing element 10 represented by the third embodiment described above will be used as an example for explanation.

[0074] A thermistor film 10a, a pair of electrode layers 12a and 12b, and a protective film 13 are formed on an insulating substrate 11.

[0075] The insulating substrate 11 is a glass substrate formed of glass material, which is generally rectangular in shape, with dimensions of 1 mm in length and 0.5 mm in width, and a thickness of 200 μm or less, preferably 150 μm or less. Specifically, the glass substrate of this embodiment has an extremely thin thickness of 100 μm or less and contains 40% to 80% silicon oxide (SiO2).

[0076] In the case of glass substrates, compared to ceramic substrates, cracking during substrate fabrication due to thinning can be suppressed, thereby enabling thinning. Furthermore, glass substrates are materials with low heat capacity and low infrared transmittance, effectively absorbing infrared radiation.

[0077] Furthermore, some thin insulating substrates deform when placed within their operating temperature range. For example, it has been confirmed that zirconia substrates deform, become brittle, and deteriorate after being placed at 150°C for 1000 hours and at 200°C for 200 hours. This deformation is believed to be a dimensional change caused by low-temperature thermal degradation resulting from changes in the zirconia crystal structure. Therefore, such dimensional changes should not occur within the operating temperature range of thin glass substrates used as temperature sensors.

[0078] Regarding the glass substrate of this embodiment, in order to suppress deformation caused by phase transitions such as changes in the chain polymer structure of the glass within the operating temperature range, the material was selected to mitigate the reduction in strength. That is, the glass substrate does not have a phase transition point that would cause deformation within the operating temperature range. It should be noted that the operating temperature range refers to the temperature range under which the non-contact temperature sensor 1 is used in various scenarios, assumed to be from -40°C to 250°C.

[0079] The thermistor film 10a is a thermistor film that functions as a temperature sensor, and it is a thermistor film made of an oxide semiconductor with a negative temperature coefficient. The thermistor film is formed on the insulating substrate 11 and on the electrode layers 12a and 12b by sputtering in a manner that spans the electrode layers 12a and 12b, and is electrically connected to the electrode layers 12a and 12b.

[0080] The thermistor film is composed of a thermistor material, which is composed of two or more elements selected from transition metals such as manganese (Mn), nickel (Ni), cobalt (Co), and iron (Fe), serving as the main component and containing a composite metal oxide with a spinel structure. Additionally, secondary components may be included to improve properties. The composition and content of the main and secondary components can be appropriately determined according to the desired characteristics.

[0081] A pair of electrode layers 12a and 12b are formed on the insulating substrate 11 and electrically connected to the temperature sensing element 10, and are arranged opposite each other with a predetermined interval. Specifically, the pair of electrode layers 12a and 12b are formed by sputtering a thin metal film, and the metal material can be a noble metal such as platinum (Pt), gold (Au), silver (Ag), palladium (Pd), ruthenium (Ru), or their alloys, such as Ag-Pd alloys. It should be noted that in this embodiment, the electrode layers 12a and 12b are formed under the thermistor thin film 10a, but they can also be formed on or within the thermistor thin film 10a.

[0082] The protective film 13 covers the area where the thermistor film 10a is formed, and covers the electrode layers 12a and 12b in such a way that at least a portion of the electrode layers 12a and 12b are exposed to form exposed portions. The protective film 13 can be formed by sputtering silicon dioxide (SiO2), silicon nitride (Si3N4), etc., or by printing lead glass, borosilicate glass, lead borosilicate glass, etc.

[0083] Next, refer to Figures 8 to 10 The connection method between the temperature sensing element 10 and the lead wire 24 is explained. Figures 8 to 10 This is a top view showing the connection method. The extension direction of the lead wire 24 is different in each method.

[0084] Figure 8 This diagram shows the lead 24 electrically connected to the electrode layers 12a and 12b at both ends of the long side of the insulating substrate 11 via laser welding. The lead 24 is orthogonal to the short side of the insulating substrate 11 and extends in opposite directions.

[0085] Figure 9 The diagram also shows the lead 24 electrically connected to the electrode layers 12a and 12b at both ends of the long side of the insulating substrate 11 via laser welding. The lead 24 is orthogonal to the long side of the insulating substrate 11 and extends in the same direction.

[0086] Figure 10 The diagram also shows the lead 24 electrically connected to the electrode layers 12a and 12b at both ends of the long side of the insulating substrate 11 via laser welding. The lead 24 extends in opposite directions, perpendicular to the long side of the insulating substrate 11 and offset from it.

[0087] Next, refer to Figure 11 and Figure 12 The evaluation of heat capacity and infrared transmittance is explained. Figure 11This is a table showing the evaluation of the heat capacity of the glass substrate of this embodiment and the alumina substrate as a comparative example. The shape (length 1mm × width 0.5mm) of the insulating substrate 11 of the temperature sensing element 10 represented by the third embodiment described above will be used as an example for explanation.

[0088] With a thickness of 70 μm, the comparative example alumina substrate has a heat capacity of 1.1 × 10⁻⁶. -4 (J / K), in comparison, the heat capacity of the glass substrate in this embodiment is 0.64 × 10⁻⁶. -4 (J / K). Furthermore, with a substrate thickness of 150 μm, the comparative example alumina substrate has a heat capacity of 2.3 × 10⁻⁶. -4 (J / K), in comparison, the heat capacity of the glass substrate in this embodiment is 1.4 × 10⁻⁶. -4 (J / K). Therefore, by using a glass substrate, the heat capacity can be reduced.

[0089] Figure 12 This is a graph representing the evaluation of infrared transmittance. The horizontal axis represents wavelength [μm], and the vertical axis represents infrared transmittance [%]. It shows the results for glass substrates with thicknesses of 70 μm and 150 μm, and for alumina substrates with a thickness of 150 μm.

[0090] As shown in the graphs, when comparing the transmittance of infrared light below 20 μm, the thin-film thermistor formed on the alumina substrate in the comparative example has an infrared transmittance of approximately 70% at wavelengths around 6.5 μm, where the energy radiation is highest in the aforementioned band, indicating significant loss. Therefore, there is a problem of decreased temperature measurement accuracy. However, in the thin-film thermistor formed on an extremely thin glass substrate, the infrared transmittance is approximately 0% at wavelengths above approximately 6.5 μm, demonstrating that infrared light is effectively absorbed by using a glass substrate. Thus, an improvement in temperature measurement accuracy can be expected.

[0091] Additionally, refer to Figure 13 The performance evaluation is explained. Figure 13 This is a table representing the thermal time constant (seconds) and the temperature reached (°C). The temperature of the object being measured is set to 200°C, and the distance between the object being measured and the non-contact temperature sensor 1 is set to 1 mm. The temperature reached (°C) is the temperature two minutes after the start of temperature measurement. In this embodiment, the glass substrate has a small heat capacity, resulting in a shorter time to reach the specified temperature, a shorter thermal time constant, and improved thermal responsiveness. Furthermore, since the glass substrate effectively absorbs infrared radiation, the temperature reached is also close to the temperature of the object being measured.

[0092] As described above, according to this embodiment, a non-contact temperature sensor capable of improving thermal response and temperature measurement accuracy can be provided.

[0093] Next, refer to Figure 14 and Figure 15 An example of the installation state of the non-contact temperature sensor 1 will be described. In this example, it is shown that the non-contact temperature sensor 1 is installed on the fuser unit of a copier, printer, etc.

[0094] First of all, Figure 14 In this process, the heating roller 20 and the pressure roller (not shown) which are the objects being tested are rotatably supported, and the heating roller 20 receives rotational driving force from the drive mechanism. The pressure roller is configured to make pressure contact with the surface of the heating roller 20 and is driven to rotate by friction at the pressing part (roll gap).

[0095] A non-contact temperature sensor 1 is mounted on the support at a distance of approximately 0.5 mm to 1.5 mm from the heating roller 20. The heating roller 20 is set to 200°C. The non-contact temperature sensor 1 receives heat from the heating roller 20, detects changes in resistance, and controls the surface temperature of the heating roller 20 to a predetermined temperature.

[0096] In this case, the temperature sensing element 10 formed on one side of the insulating substrate 11, which is a glass substrate, is arranged opposite to and toward the heating roller 20, which is the object being detected.

[0097] Next, in Figure 15 In the middle, the installation status of the non-contact temperature sensor 1 and Figure 14 The same. However, in this case, the insulating substrate 11, which serves as a glass substrate, is positioned so that the other side of the substrate faces the heating roller 20, which serves as the object being tested, and the other side of the glass substrate faces the heating roller 20.

[0098] like Figure 16 As shown, the case where the temperature sensing element 10 formed on one side (mounting surface side) of the glass substrate is opposite to the heating roller 20 side was evaluated (see reference). Figure 14 ), and the case where the other side (back side) of the glass substrate is opposite to the side of the heating roller 20 (see reference). Figure 15 ).

[0099] Figure 16 This is a table representing the thermal time constant (seconds) and the arrival temperature (°C). The arrival temperature (°C) is the temperature two minutes after the start of the temperature measurement.

[0100] The results show that, Figure 15In the installation state where the other side (back side) of the glass substrate is opposite to the heating roller 20, the thermal time constant (seconds) is short, the temperature rises rapidly, and the thermal response is good. This is believed to be due to the good infrared absorption rate of the glass substrate.

[0101] The temperature sensor 20 described in the above embodiments can be installed in various devices such as fixing units of copiers and printers, information and communication equipment such as mobile communication terminals and personal computers, imaging equipment, consumer equipment, and automotive electrical equipment to detect temperature. There are no particular limitations on the application device.

[0102] Furthermore, the present invention is not limited to the structures of the embodiments described above, and various modifications can be made without departing from the spirit of the invention. Additionally, the embodiments described above are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A non-contact temperature sensor comprising a bracket, a lead portion held in the bracket, and a temperature-sensing element electrically connected to the lead portion, characterized in that, It includes a glass substrate, wherein the glass substrate is made of a glass material on which the temperature sensing element is formed. The glass substrate will not undergo a phase transition within its operating temperature range.

2. The non-contact temperature sensor according to claim 1, characterized in that, The thickness of the glass substrate is less than 200 μm.

3. The non-contact temperature sensor according to claim 1 or 2, characterized in that, The temperature sensing element is a thin-film thermistor.

4. The non-contact temperature sensor according to claim 1, characterized in that, The temperature sensing element is connected to a lead wire, and the lead wire and the electrical connection portion connected to the lead wire are integrally formed.

5. The non-contact temperature sensor according to claim 1, characterized in that, The temperature sensing element is connected to a lead wire, and the lead wire and the electrical connection part connected to the lead wire are integrally formed.

6. The non-contact temperature sensor according to claim 4 or 5, characterized in that, The lead wire is electrically connected to the temperature sensing element by soldering.

7. The non-contact temperature sensor according to claim 1 or 2, characterized in that, The temperature sensing element is formed on one side of the glass substrate and is arranged such that the other side of the glass substrate faces the object being detected.

8. The non-contact temperature sensor according to claim 1 or 2, characterized in that, At least two ends of the glass substrate are electrically connected to the electrical connection portion connected to the lead portion via conductive paste.

9. The non-contact temperature sensor according to claim 1 or 2, characterized in that, The temperature sensing element and at least a portion of the lead wire are insulated by an insulating covering.

10. The non-contact temperature sensor according to claim 9, characterized in that, The insulating covering portion clamps and covers at least a portion of the temperature sensing element and the lead portion from both sides.

11. The non-contact temperature sensor according to claim 9, characterized in that, The insulating covering has infrared absorption capability.

12. The non-contact temperature sensor according to claim 9, characterized in that, The insulating coating absorbs at least a portion of infrared radiation in the wavelength range of 1 μm to 6 μm.

13. The non-contact temperature sensor according to claim 9, characterized in that, The insulating covering is provided only in contact with the two opposite sides of the bracket.

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