JP2006343158A - Temperature measuring instrument, and temperature measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature measuring instrument that can reduce the influence of thermal radiation light reflecting the temperature near the surface of a permeable resin member, and can improve temperature measurement accuracy of the resin interface. <P>SOLUTION: The detected wavelength ranges of first and second photodetectors 8 and 9 are shifted, and during laser welding, the first photodetector 8 detects thermal radiation light 6 that is radiated from the resin interface and permeates the permeable resin member 3 and thermal radiation light 7 radiated from the surface of the permeable resin member 3, and generates a detection signal, and the photodetector 9 detects only the thermal radiation light 7 radiated from the surface of the permeable resin member 3, and generates a detection signal. A arithmetic section 10 performs calculation so as to reduce the influence of thermal radiation light 7 based on the detection signals from the first and second photodetectors 8 and 9, and measures the temperature on the resin interface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a temperature measuring device and a temperature measuring method for measuring the temperature of an interface between the resin members when the resin members are overlapped, and laser beams having a predetermined wavelength are irradiated to the overlapped interface to weld the resin members together. About.

  Conventionally, a transparent resin member that transmits laser light and an absorbent resin member that absorbs laser light are overlapped, and the overlapped interface (resin interface) is irradiated with laser light from the side of the transparent resin member. A resin welding technique for laser welding members is known. This resin welding technique is used, for example, in the manufacture of automobile parts such as keys (remote control).

  In this laser welding, in general, infrared light having a wavelength of, for example, 810 nm is used as laser light. Further, as the transparent resin member, generally, polycarbonate or the like mixed with a colorant that transmits laser light but does not transmit visible light is used. However, in this case, it is determined whether or not sufficient welding has been performed. There was a problem that it could not be done visually.

  Therefore, a technique has been proposed in which heat radiation emitted from a resin member is detected by an infrared detector during laser welding and converted into an electrical signal by photoelectric conversion to calculate a welding temperature at the resin interface (for example, , See Patent Document 1). FIG. 4 shows a schematic configuration of a conventional temperature measuring apparatus.

  In FIG. 4, the semiconductor laser device 1 irradiates a laser beam 2 having a wavelength of 810 nm or 910 nm to a resin interface in which a transparent resin member 3 and an absorbent resin member 4 are overlapped. The infrared detector 13 has a detection wavelength range of 1500 nm to 2800 nm, and generates a detection signal by detecting the thermal radiation light 6 emitted from the vicinity of the resin interface during laser welding. The computing unit 16 measures the temperature of the resin interface based on the detection signal from the infrared detector 13.

  Further, since the laser light 2 emitted from the semiconductor laser device 1 includes noise light having a wavelength of 1300 nm to 2100 nm that overlaps the detection wavelength range of the infrared detector 13, first noise light is removed from the laser light 2. The filter 14 is provided. Further, a second filter 15 for blocking the light having the oscillation wavelength of the laser light 2 is provided between the infrared detector 13 and the resin member so as not to be affected by the reflected light of the laser light 2.

However, in reality, thermal radiation is radiated not only from the vicinity of the resin interface but also from the vicinity of the surface of the transparent resin member disposed on the laser light irradiation side. Thermal radiation from the vicinity of the surface of the resin member is also detected at the same time, which causes a problem that the S / N ratio is lowered and the measurement accuracy of the interface temperature is lowered.
JP 2004-17540 A

  In view of the above problems, the present invention provides a predetermined resin member from the permeable resin member side with respect to a resin member in which an absorbent resin member (first resin member) and a permeable resin member (second resin member) are overlapped. The first wavelength range is detected by irradiating a laser beam having a wavelength of, and detecting the emitted light from the resin member in the first wavelength range and in the second wavelength range different from the first wavelength range. By calculating the temperature of the resin interface based on the value detected in step 2 and the value detected in the second wavelength range, it is possible to reduce the influence of heat radiation that reflects the temperature near the surface of the transparent resin member. An object of the present invention is to provide a temperature measuring device and a temperature measuring method capable of improving the accuracy of temperature measurement at the resin interface.

  According to a first aspect of the present invention, there is provided the temperature measuring apparatus according to the present invention, wherein the first resin member and the second resin member having a predetermined light transmittance are overlapped with each other from the second resin member side. A laser irradiation unit that irradiates a laser beam having a wavelength of 1, a first detection unit that detects radiation light from the resin member in a first wavelength range, and radiation light from the resin member in the first wavelength range Based on a second detection unit for detecting in a second wavelength range having a different wavelength range, a value detected by the first detection unit, and a value detected by the second detection unit And an arithmetic unit that calculates the temperature of the interface between the resin member and the second resin member.

  Moreover, the temperature measuring device according to claim 2 of the present invention is the temperature measuring device according to claim 1, wherein the radiated light from the resin member is radiated in the first wavelength range and the second wavelength. An optical unit that branches into a range of emitted light and enters the first detection unit and the second detection unit is provided.

  The temperature measuring device according to claim 3 of the present invention is the temperature measuring device according to claim 1 or 2, wherein the lower limit of the second wavelength range is the first wavelength range. It is characterized by being larger than the upper limit value.

  Moreover, the temperature measuring device according to claim 4 of the present invention is the temperature measuring device according to claim 3, wherein the first wavelength range is 900 nm to 2600 nm, and the second wavelength range is 3000 nm. It is ˜14000 nm.

  According to a fifth aspect of the present invention, there is provided the temperature measurement method according to the second resin member side with respect to the resin member in which the first resin member and the second resin member having a predetermined light transmittance are overlapped. And irradiating laser light of a predetermined wavelength from the resin member to detect the radiated light from the resin member in a first wavelength range, and the radiated light from the resin member is different from the first wavelength range in the second wavelength range. Of the first resin member and the second resin member based on the value detected in the first wavelength range and the value detected in the second wavelength range. The temperature is calculated.

  The temperature measuring method according to claim 6 of the present invention is the temperature measuring method according to claim 5, wherein the lower limit value of the second wavelength range is larger than the upper limit value of the first wavelength range. It is characterized by.

  Moreover, the temperature measuring method according to claim 7 of the present invention is the temperature measuring method according to claim 5 or 6, wherein the laser beam is irradiated in a plurality of times, and the laser beam is emitted from the resin member. The detection of the emitted light is performed when the irradiation of the laser beam is stopped.

  The temperature measuring method according to claim 8 of the present invention is the temperature measuring method according to claim 7, characterized in that the period during which the laser beam irradiation is stopped is 10 μs or longer.

  According to the present invention, it is possible to reduce the influence of heat radiation reflecting the temperature in the vicinity of the surface of the second resin member on the laser beam irradiation side, and to improve the temperature measurement accuracy at the resin interface.

  Hereinafter, a temperature measuring device and a temperature measuring method according to embodiments of the present invention will be described with reference to the drawings. In the temperature measurement device and the temperature measurement method according to the present embodiment, an absorbent resin member (first resin member) and a transparent resin member (second resin member) having a predetermined light transmittance are overlapped. The resin member is irradiated with laser light having a predetermined wavelength from the transparent resin member side, and the interface (resin interface) where the absorbent resin member and the transparent resin member are overlapped is melted. An apparatus and method for measuring the temperature of a resin interface during laser welding.

(Embodiment 1)
FIG. 1 is a diagram showing a schematic configuration of a temperature measuring apparatus according to the first embodiment.
In FIG. 1, a semiconductor laser device 1 as a laser irradiation unit emits laser light (laser pulse) 2 having a predetermined constant wavelength. The laser light 2 is irradiated from the side of the transparent resin member 3 to the resin member in which the transparent resin member 3 and the absorbent resin member 4 are overlapped, and the transparent resin member 3 and the absorbent resin member 4 are lasered. Weld.

  Generally, the transparent resin member 3 disposed on the laser beam irradiation side transmits a colorant having a wavelength of, for example, 700 nm to 1600 nm, but does not transmit light having a wavelength shorter than 700 nm (for example, Orient Chemical Industries, Ltd. ), Etc., which is mixed with a product name such as “eBIND LTW-8300 (for PC)”. Instead of polycarbonate, transparent resins such as acrylic resin, polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, and ABS resin can also be used. A resin such as polypropylene or polystyrene that transmits light having a wavelength of 700 nm to 1600 nm may be used. These transparent resin members transmit light having a wavelength of 700 nm to 1600 nm, but do not transmit light having a wavelength shorter than 700 nm, absorb light having a wavelength longer than 1600 nm, and reduce its transmittance to be 2600 nm or more. The light transmission characteristic is that the light having the wavelength of substantially absorbs and the light having the wavelength of 3000 nm or more is not transmitted at all.

  Therefore, it is preferable to use a laser beam having a wavelength of 700 nm to 1600 nm. Although the case where the wavelength of the laser beam 2 is 810 nm will be described here, laser beams having other wavelengths may be used as long as they are in the range of 700 nm to 1600 nm. Although a semiconductor laser will be described as an example, other laser light such as a YAG laser may be used.

  For the absorbent resin member 4 disposed on the lower side of the transmissive resin member 3, generally, polycarbonate or the like mixed with a colorant such as carbon black that absorbs light having a wavelength of 700 nm to 1600 nm is used. A resin such as polyphthalamide that absorbs light having a wavelength of 700 nm to 1600 nm, polyethylene terephthalate, or polybutylene terephthalate may be used.

  The irradiated laser beam 2 is absorbed in the vicinity of the interface of the absorbent resin member 4, and the vicinity of the interface rises in temperature and melts. At this time, the vicinity of the interface of the permeable resin member 3 is also heated and melted by the temperature increase of the absorbent resin member 4. As a result, a molten pool 5 is generated at the resin interface. When the emission of the laser beam 2 is stopped, the temperature of the molten pool 5 is lowered and solidified, and the permeable resin member 3 and the absorbent resin member 4 are welded.

  In the process of laser welding, when the temperature near the resin interface rises, the heat radiation 6 is emitted from the vicinity of the resin interface, and when the molten pool 5 is formed, the radiation intensity becomes strong. Further, the laser beam 2 is slightly absorbed even near the surface of the transmissive resin member 3, and during irradiation with the laser beam 2, the temperature near the surface of the transmissive resin member 3 rises and weak heat radiation light 7 is emitted. . Further, when the temperature in the vicinity of the resin interface rises, the temperature conducts and the temperature in the vicinity of the surface of the transparent resin member 3 also increases, and the radiation intensity of the heat radiation 7 emitted from the vicinity of the surface of the transparent resin member 3. Become stronger.

  Usually, the temperature range used for resin welding is 150 to 500 ° C., and heat radiation light having a wavelength of 900 nm to 14000 nm is emitted, but due to the light transmission characteristics of the transparent resin member 3 described above, from the vicinity of the resin interface. Most of the emitted heat radiation having a wavelength of 2600 nm or more is absorbed by the transparent resin member 3. Therefore, the wavelength of the heat radiation 6 radiated from the vicinity of the resin interface and transmitted through the transparent resin member 3 is approximately 900 nm to 2600 nm.

  In the first embodiment, since a laser pulse (semiconductor laser) is used as the laser beam, the laser beam irradiation (ON) and the irradiation stop (OFF) are repeated at a constant frequency. Since the surface of the transparent resin member 3 is in a thermal non-equilibrium state in which heat is released into the atmosphere air, the temperature in the vicinity of the surface that has risen during the irradiation of the laser light falls while the irradiation is stopped, The temperature near the surface always changes at a frequency according to the frequency of the laser pulse. Therefore, the radiation intensity of the heat radiation light 7 always changes at a high frequency.

  The first light detection unit 8 that is the first detection unit has effective sensitivity to light in a predetermined wavelength range (first wavelength range), and radiated light from the resin member (of the transparent resin member 3). The thermal radiation light 7 radiated from the vicinity of the surface and the thermal radiation light 6) radiated from the vicinity of the resin interface and transmitted through the transparent resin member 3) are detected, and a detection signal is generated based on the radiation intensity of the detected thermal radiation light. Generate.

  Specifically, as described above, most of the heat radiation light having a wavelength of 2600 nm or more emitted from the vicinity of the resin interface is absorbed by the transparent resin member 3, so that the detection wavelength range of the first light detection unit 8 is detected. Is set to 2600 nm (the upper limit of the first wavelength range). Further, as described above, since heat radiation with a wavelength of 900 nm to 14000 nm is emitted in the resin welding, the lower limit value of the detection wavelength range of the first light detection unit 8 (the lower limit value of the first wavelength range) is 900 nm. To. Thereby, the 1st photon detection part 8 can detect the thermal radiation lights 6 and 7 of a wavelength of 900 nm-2600 nm.

  For example, an InGaAs photodiode having effective sensitivity to light having a wavelength of 900 nm to 2600 nm is used as the detection element included in the first light detection unit 8. Any other element such as a PbS photoconductive element or a PbSe photoconductive element may be used as long as the detection element has an effective sensitivity to light within this wavelength range.

  The second light detection unit 9 as the second detection unit has effective sensitivity to light in a wavelength range (second wavelength range) different from the detection wavelength range of the first light detection unit 8, and is a resin. Radiated light from the member is detected, and a detection signal is generated based on the detected radiation intensity of the heat radiation light. Here, it has effective sensitivity with respect to light in a wavelength range whose lower limit value is larger than the upper limit value of the detection wavelength range (first wavelength range) of the first light detection unit 8, and from near the surface of the transparent resin member 3. Only the emitted heat radiation light 7 is detected.

  Specifically, as described above, since the transparent resin member 3 does not completely transmit light having a wavelength of 3000 nm or more, the lower limit value of the detection wavelength range of the second light detection unit 9 (the lower limit of the second wavelength range). Value) is 3000 nm. Thereby, the 2nd light detection part 9 is not received by the influence of the heat radiation light from the resin interface vicinity. In addition, as described above, since heat radiation with a wavelength of 900 nm to 14000 nm is emitted in the resin welding, the upper limit value of the detection wavelength range of the second light detection unit 9 (the upper limit value of the second wavelength range) is 14000 nm. To. Thereby, the 2nd light detection part 9 can detect only the thermal radiation light 7 of a wavelength of 3000 nm-14000 nm.

  For example, a thermopile having effective sensitivity to light having a wavelength of 3000 nm to 14000 nm is used as the detection element included in the second light detection unit 9. The detection element may be another element such as a pyroelectric element, a bolometer, or a CdHgTe photoconductive element as long as it has effective sensitivity to light within this wavelength range.

  Since the laser light emitted from the semiconductor laser device includes weak light (noise light) having a wavelength of 1300 nm to 2100 nm regardless of the oscillation wavelength, when a semiconductor laser device is used as a laser irradiation unit, An optical element such as a filter that removes light having a wavelength of 1300 nm to 2100 nm from the laser light may be provided in front of the laser irradiation unit. Further, in consideration of the influence of the reflected light of the laser beam from the resin member, an optical element such as a filter for blocking the light having the oscillation wavelength of the laser beam is provided in front of the first and second light detection units 8 and 9. You may do it. Of course, an optical element such as a condensing lens may be provided in front of the semiconductor laser device 1 or in front of the first and second light detection units 8 and 9.

  The heat radiation light detected by the first and second light detection units 8 and 9 is converted into a current (detection signal) by the detection element and transmitted to the calculation unit 10. The calculation unit 10 calculates the temperature of the resin interface based on the values of the detection signals from the first and second light detection units 8 and 9. Specifically, the arithmetic unit 10 first amplifies each current and then recognizes the magnitude of the current as the voltage height. Next, the voltage signal obtained based on the heat radiation detected by the second light detector 9 from the voltage signal obtained based on the heat radiation detected by the first light detector 8 is subtracted from the resin interface. Recognized as a voltage value with respect to the temperature of the (molten pool). In consideration of the sensitivity of the detection element, the material characteristics of the transparent resin member 3, the plate thickness, and the surface shape, a predetermined value may be added to or multiplied by each voltage signal.

  When the temperature measured by the conventional temperature measuring apparatus described with reference to FIG. 4 is compared with the temperature measured by the temperature measuring apparatus according to the first embodiment, the temperature measured by the temperature measuring apparatus according to the first embodiment. Was lower and closer to the actual temperature. The reason for this is that, in the conventional apparatus, the temperature is measured by simultaneously detecting the heat radiation emitted from the vicinity of the surface of the transparent resin member, so that the measured temperature becomes higher than the actual temperature. In the temperature measurement device according to the first embodiment, the voltage signal obtained by simultaneously detecting the heat radiation emitted from the vicinity of the resin interface and the surface of the transparent resin member is emitted from the vicinity of the surface of the transparent resin member. This is because a voltage signal obtained by detecting only heat radiation light is subtracted and the subtracted voltage signal is recognized as a voltage value with respect to the temperature of the resin interface.

  In addition, the temperature measured by the temperature measuring apparatus according to the first embodiment was more stable with a small temperature change repeated at a high frequency. The reason for this is that, in the conventional apparatus, as described above, the heat radiation emitted from the vicinity of the surface of the transparent resin member whose radiation intensity constantly changes at a high frequency is also detected at the same time, and the temperature is measured. In the temperature measurement device according to the first embodiment, radiation from the vicinity of the surface of the transparent resin member is performed from the voltage signal obtained by simultaneously detecting the heat radiation emitted from the vicinity of the resin interface and the vicinity of the surface of the transparent resin member. This is because the voltage signal obtained by detecting only the heat radiation light to be subtracted is subtracted.

  As described above, according to the first embodiment, it is possible to reduce the influence of heat radiation light reflecting the temperature near the surface of the transparent resin member, and to improve the temperature measurement accuracy at the resin interface. it can. Even if the laser irradiation unit emits a laser pulse such as a semiconductor laser device, the influence of thermal radiation reflecting the temperature near the surface of the transparent resin member that changes every moment during laser welding is reduced. Therefore, the temperature change repeated at a high frequency is small and stable temperature measurement is possible, and the temperature measurement accuracy at the resin interface can be improved.

  In the first embodiment, the case where the transparent resin member that transmits light with a wavelength of 700 nm to 1600 nm and the absorbent resin member that absorbs light with a wavelength of 700 nm to 1600 nm are overlapped is described. When an absorbent that absorbs light having a wavelength of 700 nm to 1600 nm (for example, ink mixed with carbon black) is applied, or an absorbent film (for example, polyethylene film mixed with carbon black) is inserted at the interface. Even in the case, the same effect can be obtained. In this case, at least the upper side may be a permeable resin member, and the lower resin member is optional.

  Further, although the laser pulse is used as the laser light, CW (continuous wave) may be used, and irradiation may be performed while changing the laser power. The irradiation position of the laser beam is not limited to a fixed position, and the irradiation position of the laser beam may be made variable by relatively moving the laser beam and the object.

(Embodiment 2)
FIG. 2 is a diagram showing a schematic configuration of the temperature measuring apparatus according to the second embodiment. In addition, the same code | symbol is attached | subjected to the member same as the member demonstrated in Embodiment 1 mentioned above, and description is abbreviate | omitted.

  The temperature measuring apparatus according to the second embodiment is configured to firstly transmit heat radiation 7 radiated from the vicinity of the surface of the transparent resin member 3 and heat radiation light 6 radiated from the vicinity of the resin interface and transmitted through the transparent resin member 3. The first and second light detection units 8 and 9 have optical units that are branched into light in the detection wavelength ranges and incident on the first and second light detection units 8 and 9, respectively. Different. Specifically, the heat radiation light 7 radiated from the vicinity of the surface of the transmissive resin member 3 and the heat radiation light 6 radiated from the vicinity of the resin interface and transmitted through the transmissive resin member 3 are incident and have a wavelength of 2600 nm or less. Thermal radiation light (heat radiation light below the upper limit value of the detection wavelength range of the first light detection unit 8) and heat radiation light having a wavelength of 3000 nm or more (more than the lower limit value of the detection wavelength range of the second light detection unit 9) A wavelength branching filter that splits heat radiation light having a wavelength of 2600 nm or less into the first light detection unit 8 and makes heat radiation light with a wavelength of 3000 nm or more enter the second light detection unit 9. Is provided.

  In FIG. 2, the heat radiation light 7 radiated from the vicinity of the surface of the transparent resin member 3 and the heat radiation light 6 radiated from the vicinity of the resin interface and transmitted through the transparent resin member 3 are taken into the same unit.

  The wavelength branching filter 11 reflects the heat radiation light having a wavelength of 2600 nm or less out of the incident heat radiation light on the surface, and causes the first light detection unit 8 to enter. On the other hand, thermal radiation having a wavelength of 3000 nm or more is transmitted and incident on the second light detection unit 9.

  The material of the wavelength branching filter 11 is, for example, ZnSe or the like that exhibits high transmittance with respect to light with a wavelength of 3000 nm to 14000 nm, and a coating that improves the reflectance with respect to light with a wavelength of 900 nm to 2600 nm is applied to the surface. As for the material, other materials such as silicon, sapphire, germanium, calcium fluoride, and synthetic quartz may be used as long as they transmit light having a wavelength of 3000 nm or more. In addition, the structure which permeate | transmits the light of a wavelength of 2600 nm or less and reflects the light of a wavelength of 3000 nm or more may be sufficient.

  According to the second embodiment, the heat radiation light 6 from the vicinity of the resin interface and the heat radiation light 7 from the vicinity of the surface of the transparent resin member 3 are simultaneously taken into the apparatus, and the wavelength branching filter 11 provided in the apparatus is used. Compared with a device in which heat radiation light can be incident on the first light detection unit 8 and the second light detection unit 9, respectively, and the optical paths for guiding the heat radiation light to the first and second light detection units are independent from each other. The device can be made smaller.

  In addition, since the detection wavelength ranges of the first and second light detection units 8 and 9 do not overlap with each other, for example, a half mirror that divides heat radiation light having a wavelength of 900 nm to 14000 nm into two may be used. In this case, the heat radiation light 7 radiated from the vicinity of the surface of the transparent resin member 3 and the heat radiation light 6 radiated from the vicinity of the resin interface and transmitted through the transparent resin member 3 are reflected and transmitted to be reflected or transmitted. Thermal radiation light can be incident on the first light detection unit 8, and transmitted or reflected heat radiation light can be incident on the second light detection unit 9.

  Further, the irradiation position of the laser beam is not limited to a fixed position, and the irradiation position of the laser beam may be varied by relatively moving the laser beam and the object. The unit that takes in the heat radiation 7 emitted from the vicinity of the surface of the transparent resin member 3 and the heat radiation 6 emitted from the vicinity of the resin interface and transmitted through the transparent resin member 3 is also moved.

(Embodiment 3)
In the temperature measurement device according to the third embodiment, the calculation unit is in the OFF period of the laser light in synchronization with ON / OFF (laser light irradiation and irradiation stop) of the laser light (laser pulse) emitted from the semiconductor laser device. It is characterized in that the detection signal is captured only during (irradiation stop period).

  FIG. 3A shows a schematic configuration of the temperature measuring apparatus according to the third embodiment, and FIG. 3B shows a detection signal capture timing by the calculation unit. Note that the same members as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, the light detection unit 12 detects thermal radiation 7 emitted from the vicinity of the surface of the transparent resin member 3 and thermal radiation 6 emitted from the vicinity of the resin interface and transmitted through the transparent resin member 3. A detection signal is generated based on the detected radiation intensity of the heat radiation light. Here, the detection wavelength range of the light detection unit 12 is set to 900 nm to 2600 nm, but may be a wavelength range including at least this wavelength range.

  In addition, the arithmetic unit 10 has a mechanism for capturing a detection signal from the light detection unit 12 in synchronization with ON / OFF of the laser beam 2 (laser pulse) from the semiconductor laser device 1. Specifically, the detection signal from the light detection unit 12 is captured only during the laser beam OFF period (irradiation stop period).

  Thus, since the detection signal is captured only during the OFF period of the laser pulse, it is difficult to be affected by the heat radiation from the vicinity of the surface of the transmissive resin member 3. That is, as described above, the temperature in the vicinity of the surface of the transparent resin member 3 that has increased during the laser pulse ON period (irradiation period) decreases during the laser pulse OFF period (irradiation stop period). Therefore, since the radiation intensity of the heat radiation emitted from the vicinity of the surface of the transparent resin member 3 during the OFF period of the laser pulse becomes weak, if the detection signal is captured only during the OFF period of the laser pulse, the temperature measurement is performed. It is possible to make it less susceptible to the influence of heat radiation from the vicinity of the surface of the transparent resin member 3 that causes noise, and the accuracy of temperature measurement can be improved.

  Further, the light detected by the light detection unit during the irradiation of the laser light includes reflected light of the laser light, which becomes an obstacle to accurate temperature measurement. In addition, when a semiconductor laser device is used, noise light of 1300 nm to 2100 nm is mixed in the laser light as described above, and the reflected light of the noise light also becomes an obstacle to temperature measurement. Therefore, in order to eliminate the influence of these reflected lights (disturbance light), an optical element that removes noise light from the laser light is provided in front of the semiconductor laser device, or light of the oscillation wavelength of the laser light is placed in front of the light detection unit. Although it is necessary to provide an optical element that shuts off, the temperature measurement device captures the detection signal during the laser beam irradiation stop period, so that the influence of reflected light can be avoided without providing an optical element such as a filter. Therefore, it is possible to reduce the cost of the apparatus.

  Further, the laser pulse emitted from the semiconductor laser device is set so that the ON period is equal to or longer than the OFF period (the ratio of the laser light irradiation period is 0.5 or more). That is, when the ratio of the ON period of the laser pulse is less than 0.5, the non-irradiation time becomes longer than the irradiation time, and the temperature at the resin interface greatly decreases when the irradiation is not performed. When the process is repeated, the increase / decrease width of the resin interface temperature in a short time increases, resulting in a decrease in bonding quality and a decrease in temperature measurement accuracy. In order to stabilize the welding by reducing the increase / decrease width of the resin interface temperature in a short time, the ratio of the ON period of the laser pulse needs to be 0.5 or more. The higher this ratio is, the more preferable it is 0.9 or more.

  The OFF period (irradiation stop period) is 10 μs or longer. That is, since the detection signal is captured only during the OFF period, if the OFF period is shorter than 10 μs due to the influence of the rise time of the captured signal, the measurement temperature varies and the temperature measurement accuracy decreases. Needs to be 10 μs or more.

Hereinafter, the ON period (irradiation period) and the OFF period (irradiation stop period) of the laser pulse will be specifically described.
When the laser pulse irradiation start (laser pulse rise) and detection signal capture start timing are 1 ms cycle (repetition frequency is 1 kHz), the laser pulse ON period is 900 μs, and the detection signal capture period is 50 μs, The measurement temperature is stable with small changes in temperature repeated at a high frequency, improving the accuracy of temperature measurement. This is because the temperature in the vicinity of the surface of the transparent resin member 3 decreases during the laser beam irradiation stop period, the radiation intensity level of the heat radiation emitted from the vicinity of the surface of the transparent resin member 3 decreases, and the light detection unit This is because the light detected at 12 becomes heat radiation light emitted from the vicinity of the resin interface.

  Next, the period was set to 1 ms, the detection signal capture period was fixed to half of the OFF period of the laser pulse, and the ON period was changed from 50 μs to 950 μs. The temperature could be measured with very high accuracy. When the time was shorter than 900 μs, the temperature change gradually increased, and when the time was shorter than 500 μs, the temperature change became extremely large. As a result of performing the same temperature measurement in other periods, the temperature measurement was small and stable when the ratio of the laser beam irradiation period was 0.5 or more.

  Next, the period was set to 1 ms, the ON period of the laser pulse was fixed to 900 μs, and the detection signal capture period was changed from 5 μs to 95 μs. As a result, the temperature change was small and stable temperature measurement was achieved at 10 μs or more. As a result of performing the same temperature measurement in other periods, the temperature change was small and stable temperature measurement was possible when all were 10 μs or more.

  Here, the case where the calculation unit captures the detection signal only during the laser beam irradiation stop period has been described. However, for example, light shielding such as a shutter that operates in synchronization with ON / OFF of the laser pulse in front of the light detection unit. Means may be provided so that only the heat radiation emitted during the laser beam irradiation stop period is incident on the light detection unit.

  Further, as described above, considering that the temperature in the vicinity of the surface of the permeable resin member increases due to heat conduction from the vicinity of the resin interface (molten pool), the more the temperature in the vicinity of the resin interface increases, the more the permeable resin. The temperature in the vicinity of the surface of the member also rises and becomes a noise during temperature measurement, which hinders accurate temperature measurement.

  Therefore, the configuration of the temperature measurement device according to the third embodiment may be applied to the temperature measurement device according to the first embodiment described above. That is, the detection signal capturing operation in the arithmetic unit 10 is performed in synchronization with the laser pulse. In this way, the accuracy of the measurement temperature can be further improved.

  In addition, although laser pulses are used here as laser light, CW (continuous wave) may be used, and the laser irradiation unit irradiates the laser light at least once while irradiating the resin interface with the laser light. What is necessary is just to be able to set the period to stop (irradiation stop period).

  As described above, according to the first to third embodiments, when laser welding is performed on a resin member in which an absorbent resin member and a transparent resin member are overlapped, the heat radiation light from the resin member is changed to the first wavelength range. In addition, the temperature near the surface of the transparent resin member is reflected in the heat radiation that reflects the temperature near the resin interface by detecting in the second wavelength range that is different from the first wavelength range. The effect of heat radiation reflecting the temperature in the vicinity of the surface of the transparent resin member can be reduced from the heat radiation light superposed on the heat radiation light, and the temperature measurement accuracy at the resin interface can be improved. Resin bonding quality can be supplied stably. Therefore, it is possible to supply a high-quality resin member at a low cost, which is useful for, for example, a resin bonding apparatus used for manufacturing a camera barrel for a mobile phone.

  Further, according to the third embodiment, the laser beam is irradiated in a plurality of times, and the detection of the heat radiation light from the resin member is performed when the laser beam irradiation is stopped. The temperature measurement accuracy can be improved.

  The temperature measuring device and the temperature measuring method according to the present invention can improve the temperature measurement accuracy of the resin interface when laser members are overlapped and laser welded, and can stably supply high resin bonding quality. Therefore, it becomes possible to supply a high-quality resin member at a low cost, which is useful for a resin bonding apparatus used for manufacturing a camera barrel for a mobile phone or the like.

The figure which shows schematic structure of the temperature measuring apparatus which concerns on Embodiment 1 of this invention. The figure which shows schematic structure of the temperature measuring apparatus which concerns on Embodiment 2 of this invention. (A) is a figure which shows schematic structure of the temperature measuring device which concerns on Embodiment 3 of this invention, (b) shows the capture timing of the detection signal by the calculating part of the temperature measuring device which concerns on Embodiment 3 of this invention. Figure The figure which shows schematic structure of the conventional temperature measuring device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor laser apparatus 2 Laser beam 3 Transparent resin member 4 Absorbent resin member 5 Molten pool 6, 7 Thermal radiation light 8 1st light detection part 9 2nd light detection part 10, 16 Calculation part 11 Wavelength branch filter 12 Photodetector 13 Infrared detector 14 First filter 15 Second filter

Claims (8)

A laser irradiation unit configured to irradiate a laser beam having a predetermined wavelength from the second resin member side with respect to the resin member in which the first resin member and the second resin member having a predetermined light transmittance are superimposed;
A first detection unit for detecting radiation light from the resin member in a first wavelength range;
A second detector for detecting the emitted light from the resin member in a second wavelength range different from the first wavelength range;
An arithmetic unit that calculates the temperature of the interface between the first resin member and the second resin member based on the value detected by the first detection unit and the value detected by the second detection unit When,
A temperature measuring device comprising:   2. The temperature measuring device according to claim 1, wherein the radiation from the resin member is branched into radiation light in the first wavelength range and radiation light in the second wavelength range, and the first detection unit. And a temperature measurement device comprising an optical unit that is incident on the second detection unit.   The temperature measurement device according to claim 1, wherein a lower limit value of the second wavelength range is larger than an upper limit value of the first wavelength range.   The temperature measuring apparatus according to claim 3, wherein the first wavelength range is 900 nm to 2600 nm, and the second wavelength range is 3000 nm to 14000 nm.   A laser beam having a predetermined wavelength is irradiated from the second resin member side to the resin member in which the first resin member and the second resin member having a predetermined light transmittance are overlapped, and from the resin member In the first wavelength range, the emitted light from the resin member is detected in a second wavelength range that is different from the first wavelength range, and is detected in the first wavelength range. A temperature measurement method comprising calculating a temperature of an interface between the first resin member and the second resin member based on the measured value and a value detected in the second wavelength range.   The temperature measurement method according to claim 5, wherein a lower limit value of the second wavelength range is larger than an upper limit value of the first wavelength range.   The laser beam is irradiated in a plurality of times, and the detection of the emitted light from the resin member is performed when the irradiation of the laser beam is stopped. Temperature measurement method. The temperature measurement method according to claim 7, wherein a period during which the laser light irradiation is stopped is 10 μs or more.

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