LED light source device

Abstract

Even with LED elements that have a short lifespan, this invention provides a long-life LED light source device equipped with multiple LED elements of the same wavelength, and a mechanism that automatically replaces LEDs with new ones when their output decreases. [Solution] In an LED light source device that can emit LED light of various wavelengths by coupling LED elements 1 and 1a of various wavelengths to a rotating disc 3, the LED element 1a with a short lifespan is fixed to detachable spring materials 5a and 5b, and when its lifespan is reached, a spare LED element 6a of the same wavelength located in a replacement LED box 7 installed on the side is aligned with it by an automatic moving mechanism 8a to 8c, and then pushed out using an automatic moving replacement mechanism 9a to 9d, thereby replacing the LED element 1a that has reached the end of its lifespan set in the detachable spring materials 5a and 5b by pushing it out of the spring materials 5a and 5b, thereby providing a long-life LED light source device.

Description

Technical Field

[0001] The present invention relates to a multi-wavelength LED light source, and more particularly to an inexpensive, long-life, highly stable automatic LED replacement type light source device.

Background Art

[0002] Multi-wavelength light source devices are used in the manufacturing of semiconductor wafers or wafers, inspection, testing, and characteristic measurement of materials used in the fields of bio and medicine. As this type of multi-wavelength light source, Patent Document 1 and Non-Patent Document 1 are multi-wavelength LED light source devices using a large number of LEDs. Also, Patent Documents 2, 3 and Non-Patent Document 2 obtain a long-life continuous multi-wavelength light source by maintaining the discharge gas of a xenon lamp with laser light. Further, Patent Document 4 discloses a continuous multi-wavelength light source using a photonic fiber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Multi-wavelength light sources are used for inspection, testing, and characterization of materials used in semiconductor wafers or wafer manufacturing, as well as in the bio and pharmaceutical fields. They are also used in semiconductor manufacturing lines as devices that irradiate products with 10 to 20 different wavelengths of light to evaluate them as they move along the line. For manufacturing line applications, a lifespan of 10,000 hours or more is required. While the method of obtaining a multi-wavelength light source using multiple LEDs, as described in Patent Document 1 and Non-Patent Document 1, is inexpensive, when the wavelength is changed by rotation, the lifespan of LEDs in the ultraviolet range of 200 nm to 300 nm is short at 1,000 hours. Therefore, it was not possible to create a multi-wavelength light source with a long lifespan of 10,000 to 20,000 hours using a large number of LEDs due to this lifespan limitation.

[0006] When evaluating products moving along a semiconductor manufacturing line, for example, by irradiating them with 10 to 20 different wavelengths of light, extremely high-speed LED movement and stopping are required when using a system that rotates LEDs of multiple wavelengths. For example, if 20 different wavelength LEDs are attached to a disc-shaped substrate and the disc is rotated and stopped at high speed, only 50 msec can be used for movement and stopping (movement time to the next LED and measurement time by the LED) in order to evaluate one product in less than one second. It is extremely difficult to perform this high-speed rotation and stopping with current stepping motors. Patent document 1 is a published document that describes rotating LEDs, but it does not describe any measures for high-speed operation.

[0007] In the methods described in Patent Document 1 and Non-Patent Document 1, which use multiple LEDs to obtain a multi-wavelength light source, when the light output is directed onto an object using optical fibers or liquid light guides, there is no material that transmits both wavelengths from 200nm to 400nm and wavelengths from 1000nm to 1700nm. As a result, the fiber must be manually replaced each time, which has the disadvantage that it is not possible to automatically irradiate light from 200nm to 1700nm on a manufacturing line.

[0008] In the methods described in Patent Document 1 and Non-Patent Document 1, which use multiple LEDs to obtain a multi-wavelength light source, if the LED emission wavelength is, for example, 280 nm, the emitted wavelength is in the range of ±10 nm around 280 nm. Even if an external spectrometer is used to obtain 280 nm light, a wavelength shift of several nm occurs due to changes in room temperature and LED temperature. As a result, the intensity shifts from the center, the output decreases, and it has the disadvantage of not being usable in fields such as bio and pharmaceuticals where a wavelength width of 1 nm is required.

[0009] Patent documents 1, 2, and 3, as well as non-patent documents 1 and 2, require a 20 to 30 minute buffer time to allow the device to start up and stabilize the light output, including temperature stabilization of the LEDs and the xenon lamp device, which is a drawback in terms of use.

[0010] For evaluating and inspecting products moving at high speeds, such as in semiconductor manufacturing lines, there is a demand for multi-wavelength light sources with a lifespan exceeding 10,000 hours. Patent documents 2 and 3 describe how, when using a conventional xenon lamp alone, the lifespan was only about 5,000 hours due to electrode wear, but by initiating light emission with electrodes and then using an external laser beam for subsequent emission, it was successful to extend the lifespan to 10,000 hours. However, for manufacturing line applications, even longer lifespans are needed.

[0011] Patent Document 2 and Non-Patent Document 2 describe obtaining light emission by irradiating a xenon lamp discharge gas with high-power laser light from an external source. Patent Document 3 describes realizing a multi-wavelength light source by electrodeless discharge of xenon gas using three high-power lasers. Furthermore, Patent Document 4 describes obtaining a multi-wavelength light source by irradiating a nonlinear fiber with a high-power short-pulse laser. However, these patent documents 2, 3, 4, and Non-Patent Document 2 have the disadvantage of not being inexpensive because they require very expensive high-power lasers, laser power supplies, and their control systems.

[0012] Patent Document 4 describes a continuous-wavelength light source using a nonlinear crystal and a laser. This light source can achieve a wavelength resolution of 1 nm and a stability of 0.5%. However, it had the drawback of being difficult to emit light in the 200 nm to 300 nm range.

[0013] In conventional LED light sources, fluctuations in external temperature, mainly during air cooling or heating to maintain a constant indoor temperature, caused a change of several degrees in the temperature of the air drawn in by the fan of the LED light source device, resulting in LED output fluctuations (0.1% to 1%) and wavelength shifts. [Means for solving the problem]

[0014] In recent years, LED performance has improved dramatically, and the wavelength range has expanded from above 200nm to the 1650nm and 1900nm regions. High-power LEDs (50mW to 1W) at over 50 different wavelengths are now readily available at low cost. In the future, it is expected that high-power, inexpensive LEDs will be usable at multiple wavelengths in the ultraviolet region of 200nm to 300nm. Furthermore, discharge tube type light sources, which have been used until now, are rapidly being replaced by LEDs. Without using extremely expensive high-power lasers for gas discharge as described in Patent Documents 2 and 3 and Non-Patent Document 2, nor without using extremely expensive technologies as described in Non-Patent Document 4, this invention provides an extremely inexpensive device by using multiple LEDs.

[0015] LED light sources, excluding those in the ultraviolet range, now have an extremely long lifespan, said to be between 20,000 and 40,000 hours. This invention addresses the short lifespan of, for example, 1,000 hours for LEDs in the ultraviolet range by enabling automatic replacement of LEDs that have reached the end of their lifespan. As a result, by setting up a set of 20 new LEDs for replacement, the lifespan can be extended to 20,000 hours.

[0016] This invention involves fixing multiple LEDs to a rotating disc and, in order to switch wavelengths at high speed by rotating the disc, providing an extremely simple and lightweight LED holder on the surface of the rotating disc that allows the LEDs to be attached and detached. This reduces the load on the stepping motor, enables high-speed rotation and stopping of the rotating disc, sets the LED wavelength switching time to 10 msec, and allows more than 20 different LED wavelengths of light to be emitted per second.

[0017] Conventionally, when extracting light using optical fibers or liquid light guides, there were no materials that transmitted both 200nm to 400nm light and 1000nm to 1700nm light, so manual replacement was the only option. This invention extracts the light emitted from an LED element using multiple optical fibers or liquid light guides attached to multiple locations and irradiates an object, or the light from multiple optical fibers or liquid light guides is combined with a dichroic mirror and irradiated, thereby enabling the automatic extraction of 200nm to 1700nm light.

[0018] This invention features a structure in which light emitted from an LED element is extracted using multiple optical fibers or liquid light guides attached to multiple locations. By providing multiple extraction ports on the rotating disc, multiple LED elements can be sequentially pulsed with each rotation of the disc, resulting in multiple light sources being obtained in a single step of rotation, thus enabling high-speed switching of wavelengths during illumination.

[0019] This invention achieves a longer lifespan by allowing replacement of LEDs that have reached the end of their lifespan even during operation. This is achieved by stacking multiple identical LEDs next to a high-speed disc with LEDs that move at high speed, and automatically pushing out one of the LEDs that has reached the end of its lifespan, thereby sliding out the LED that has reached the end of its lifespan from a fixed position.

[0020] The replacement LED of the present invention is characterized by stacking 10 to 20 LEDs of each wavelength for several types of LEDs with short lifespans, and by automatically moving the LED element to be replaced to the LED replacement location.

[0021] The LED replacement system of the present invention is characterized in that the output of each LED is measured by a photodetector provided outside, and when the output decreases, it is automatically replaced.

[0022] The light emission of the LED of the present invention may be such that all LEDs emit light constantly in CW, or may be in a mode of emitting light in pulses only when set to rotate at the output part of a specified device (where an optical fiber is coupled, or there is a lens, or the light as it is from the LED element).

[0023] In addition to attaching LEDs to a rotating disk, the present invention may also be a method in which LEDs are set in a fixed part in a row, and the row of LEDs is pushed by an automatic device from the side, so that the LEDs slide and the light-emitting part changes, thereby achieving a longer lifespan or being able to change the wavelength of the LEDs.

[0024] The present invention is characterized in that a Peltier element and a thermometer are attached to the LED element. Even when the LED element is not emitting light, the Peltier element is operated to raise the temperature in the reverse direction to raise the temperature of the LED element and keep it at the temperature during the light-emitting operation, or a pulsed current is applied simultaneously with the light emission of the LED element to bring the temperature of the LED close to the temperature during operation and significantly reduce the time until the light emission output at start-up is stabilized.

[0025] The present invention is characterized in that a Peltier element and a thermometer are attached to the LED element. When the LED element emits light, by keeping the LED element at a predetermined temperature by the Peltier element, the drawback that the wavelength of the light emission shifts by several nm due to the temperature change of the LED element or the temperature change of the room temperature is eliminated, and a wavelength shift of 1 nm or less is achieved.

[0026] The present invention is characterized in that a heater and a thermometer are attached instead of the Peltier element described above. Even when the LED element is not emitting light, the temperature of the LED element is raised and kept at the temperature during the light-emitting operation, or a pulsed current is applied simultaneously with the light emission of the LED element to bring the temperature of the LED close to the temperature during operation and significantly reduce the time until the light emission output at start-up is stabilized.

[0027] The present invention is characterized by replacing the Peltier element described above with a heater and a thermometer, and by maintaining the LED element at a predetermined temperature using the heater when the LED element emits light, the drawback that the wavelength of the light emitted shifts by several nanometers due to temperature changes of the LED element and the room temperature is eliminated.

[0028] This invention, by attaching a Peltier element and thermometer, or a heater and thermometer, to an LED element, allows the temperature of the LED element to be raised even when it is not emitting light, maintaining it at the temperature required for illumination. When the LED is illuminated, a constant output can be obtained immediately. Furthermore, compared to operating with all LEDs constantly illuminated, the LEDs emit pulsed light only when in use, extending their lifespan by more than 10 times.

[0029] The present invention is characterized by providing a photodiode to measure the light output and controlling the current flowing through the LED element or the voltage applied to the LED based on that value to achieve output stability.

[0030] The present invention is characterized by providing an external cooling fan for the LED light source device, a thermometer to measure the temperature of the air entering from the fan, and a Peltier element to control the temperature of that air, thereby reducing fluctuations in LED output and wavelength shifts due to changes in room temperature. [Effects of the Invention]

[0031] In this invention, by using inexpensive LEDs instead of expensive gas discharge or laser multi-wavelength light sources used in conventional manufacturing lines, we were able to obtain an extremely inexpensive multi-wavelength light source.

[0032] In this invention, by mounting LEDs on a rotating disc and rotating it to generate multiple wavelengths, and by providing a mechanism that allows for the automatic replacement of LEDs in the wavelength range with short lifespans during operation multiple times, it was possible to obtain a light source with a lifespan more than 10 times longer than light sources using multiple LEDs, and more than twice as long as conventional gas discharge type multi-wavelength light sources.

[0033] In this invention, an extremely lightweight LED holder is directly soldered to the rotating disc, and replacement LEDs are pushed out from the side. This reduces the load on the stepping motor, enables high-speed switching of LED wavelengths, and allows for automatic replacement of LEDs that have reached the end of their lifespan during high-speed operation.

[0034] In this invention, by providing multiple optical fibers or liquid light guides, it is possible to automatically obtain light from 200 nm to 1700 nm, and since multiple wavelengths can be emitted in a single rotation step, it is possible to rapidly switch between multiple wavelengths.

[0035] The shape of the LED element, whether flat or lens-shaped, affects the position of the optical input surface of the optical fiber or liquid light guide relative to the LED element surface. Therefore, by incorporating a mechanism to move the optical fiber or liquid light guide to set the distance between them to the order of 0.1-0.2 mm, it became possible to use LED elements of various structures.

[0036] In this invention, by attaching a Peltier element and a thermometer to the LED, and raising the temperature to the operating temperature before light emission, or by applying a pulsed current to the Peltier element simultaneously with light emission to raise the LED temperature, the time required for the initial light output to stabilize was significantly reduced.

[0037] In this invention, by attaching a Peltier element and a thermometer to the LED and stabilizing the LED's temperature during light emission, it was possible to reduce the wavelength fluctuation of several nanometers caused by temperature changes of the LED element and room temperature to less than 1 nm.

[0038] In this invention, by attaching a heater and thermometer to the LED, the temperature is raised to the operating temperature before light emission, or a pulsed current is applied to the heater simultaneously with light emission to raise the LED temperature, thereby significantly reducing the time it takes for the light output to stabilize at startup.

[0039] In this invention, by attaching a heater and a thermometer to the LED and stabilizing the LED temperature during light emission, it was possible to reduce the wavelength fluctuation of several nanometers caused by temperature changes of the LED element and room temperature to less than 1 nm.

[0040] In this invention, by attaching a Peltier element and a thermometer to the inlet of the cooling fan that cools the device, the temperature of the air entering from the fan can be kept constant, and fluctuations in LED output (0.1% to 1%) and wavelength shifts due to rapid changes in room temperature can be reduced to a fraction of their original levels. [Brief explanation of the drawing]

[0041] [Figure 1] This is an overall diagram of the apparatus related to the present invention. [Figure 2] This is a diagram of an LED element. [Figure 3] This is the LED holder and its cross-sectional view. [Figure 4] This diagram shows a method in which the LED element slides horizontally. [Figure 5] This diagram shows multiple optical fibers or liquid light guides attached. [Figure 6] This is a diagram showing the moving part that brings the optical fiber or liquid light guide closer to the LED element. [Figure 7] This diagram shows a Peltier element and a thermometer attached below an LED element. [Figure 8] This is a diagram showing the wavelength distribution of the LED output. [Figure 9] This diagram shows the shift in the emission wavelength of an LED due to temperature. [Figure 10] This diagram shows the decrease in LED output due to LED junction temperature. [Figure 11]This is a diagram illustrating an experiment in preheating control to suppress output fluctuations during the initial stages of light emission. [Figure 12] This is an overview diagram showing a cooling fan with a Peltier element attached, which is used to draw air into the entire device. [Figure 13] This diagram illustrates an experiment demonstrating the output fluctuations when a Peltier element is attached to a fan that draws air into the entire device. [Figure 14] This diagram illustrates an experiment showing the output fluctuations when the fan that draws air into the entire device is not temperature-controlled. [Modes for carrying out the invention]

[0042] Figure 1 shows an embodiment relating to the multi-wavelength LED light source device of the present invention. In Figure 1, LED elements 1 and 1a (the symbol a indicates a replaceable LED element) are fixed to a rotating disc 3 by extremely simple and lightweight LED holders 5, 5a, and 5b that allow the LED elements 1 and 1a to be attached and detached (5a and 5b are the LED holders for the replaceable part). The LED elements 1 and 1a can be easily removed by pushing them in the longitudinal direction (arrow X) of the holders 5, 5a, and 5b. 2 is the light-emitting part of the LED.

[0043] The rotating disc is a heat-conducting substrate for dissipating heat from the LEDs, and its material is aluminum, high thermal conductivity graphite, or composite material (a composite material that integrates high thermal conductivity graphite with dissimilar materials (aluminum, copper, etc.) from Thermographics Inc., with a thermal conductivity twice that of copper).

[0044] The rotating disc 3 described above starts rotating at high speed using a stepping motor 4 (Oriental Motor Co., Ltd.'s stepping motor AZM46AK and driver AZD-K), and stops when a new LED element arrives at the location of the optical fiber or liquid light guide 17. After stopping, measurement is performed based on the light emission of the LED element. The measurement time depends on the object being measured, but is generally between 50 msec and 100 msec. This operation is then repeated for all LED elements. When 10 LED elements are attached to the rotating disc, and the size of the rotating disc is 80 mm in diameter and 3 mm thick aluminum, it was possible to move from the stopping position of one LED element to the stopping position of the next LED element in 10 msec. The angular change of movement at this time was 10 degrees with an angular error of 0.18 degrees, and if the area of ​​the LED light-emitting part is 1 mm x 1 mm, the position resolution is 60 microns, which is sufficient accuracy. By using this stepping motor, it is possible to further improve the angular error by more than an order of magnitude.

[0045] In Figure 1, 13 is the power supply line to the LED element from an external source, and 14 is a MOFLON slip ring MT0522-S15, which ensures the power supply line remains in a constant position as the device rotates.

[0046] LED elements 1 and 1a (where 'a' indicates a replacement LED) are LED elements with wavelengths ranging from ultraviolet to far-infrared, specifically from 200 nm to 1650 nm and 1900 nm. For example, the 280 nm LED is the NCSU434C from Nichia Corporation. If the output of an LED element is detected to be low by an externally installed optical measuring instrument 18, LED element 1a can be replaced when it is on the right side of the rotating disc.

[0047] The replacement involves moving the LED stack box 10, which contains LED elements 6a and 6 (where 'a' indicates the replacement LED) with the same wavelength as the LED element 1a to be replaced, located in the replacement LED box 7 on the right side of Figure 1, to the replacement position on the rotating disc. For this movement, a movement mechanism 8a to 8c is used to move the replacement LED box 7 up and down. Here, 8a is a stepping motor (a stepping motor and driver PK523HPMA-CRD5107HPB from Oriental Motor Co., Ltd.), 8b is a gear, and 8c is a screw rod for vertical movement.

[0048] The replacement LED box 7 contains multiple LED elements of various wavelengths. In Figure 1, there are only two stack boxes 10, but the number of boxes contains the number of LED elements corresponding to the type of LED element to be replaced. All of the LED elements 11 inside are LED elements of the same wavelength and are pushed forward by the spring 12.

[0049] The number of replacement LED elements 6, 6a, and 11 is such that, if the LED elements have a lifespan of 1000 hours, 20 of them can be set in the LED stack box 10, enabling long-term operation of 20,000 hours.

[0050] The method for replacing LED element 1a involves replacing it with a new LED element 6a of the same wavelength using replacement movement mechanisms 9a to 9d. The rotation of the stepping motor (Oriental Motor Co., Ltd. stepping motor and driver PK523HPMA-CRD5107HPB) 9a rotates the gear 9c, which moves the threaded rod 9b. This pushes the push plate 9d attached to the tip of the central rod 9e of the threaded rod in the direction of the X arrow (left), moving the LED element 6a to the left and pushing the LED element 1a to be replaced out of the LED holding parts 5a and 5b on the rotating disc 3. The pushed-out LED element 1a is directed forward by the circularly curved discharge rod 15 and falls straight down. The fallen LED element 5a enters the collection box 16.

[0051] Figure 2 shows an LED element 1a. The LED element 1a has the light-emitting part 2 of the LED enclosed in silicon resin or quartz. The back surface of the LED element has an anode electrode 19a and a cathode electrode 19b necessary for the LED to emit light. Type 1 is flat, and type 2 has a lens.

[0052] Figure 3 is a cross-sectional view of the LED element 1a during replacement. Inside the LED element 1a is the light-emitting part 2 of the LED itself. Behind the rotating disc 3 are heat dissipation fins 20. The LED element is fixed to the rotating disc 3 by retaining parts 5a and 5b made of extremely thin spring material so that it can be attached and detached. By pushing the LED element 1a in a direction perpendicular to the plane of the paper in the right-hand diagram of Figure 3, the LED element 1a can be easily removed from the retaining parts 5a and 5b. The surface of the rotating disc 3 is coated with an insulating film 21, and electrodes 22a and 22b for the cathode and anode of the LED element 1a are joined to it. Paste solder (M705, manufactured by Senju Metal Co., Ltd.) is applied to electrodes 22a and 22b by screen printing, and the retaining parts 5a and 5b are soldered by solder reflow. Because the connection point between the rotating disc and the LED element is extremely lightweight, the load on the stepping motor is drastically reduced, allowing for an extremely short wavelength change time for the LED. 19a and 19b are the anode and cathode electrodes of the LED element.

[0053] Figure 4 shows an embodiment of a method in which the LED element is slid laterally. The LED element 1a to be replaced is placed close to the optical fiber 17. The LED element is placed inside a sliding plate 25 and can be moved by pushing it to the left in the diagram. The movement to replace LED element 1a with a new element 6a of the same type is performed by the replacement movement mechanism 9a to 9d. The rotation of the stepping motor (Oriental Motor Co., Ltd. stepping motor and driver PK523HPMA-CRD5107HPB) 9a rotates the gear 9c, which moves the threaded rod 9b, and pushes the push plate 9d attached to the tip of the central rod 9e of the threaded rod in the direction of the X arrow (left), thereby moving the LED element 6a to the position of the optical fiber.

[0054] Figure 5 shows a configuration in which multiple optical fibers or liquid light guides (17a, 17b) are attached to multiple LED elements 1c and 1d with different wavelengths mounted on a rotating disk. For example, as optical fibers, Thorlabs' M92L, which transmits from 250nm to 1200nm, and Thorlabs' M107L optical fibers, which transmit from 400nm to 2200nm, can be used. As liquid light guides, KLV.CO.LTD's Series 250, which transmits from 220nm to 650nm, and Series 2000, which transmits from 420nm to 2000nm can be used. Two or more light sources can be combined using a conventional dichroic mirror (Thorlabs DMBP740B) to form a single fiber or liquid light guide, or they can be used directly to illuminate the sample. In this case, when one LED is emitting light, the other LED is either stopped, or, if all LED elements are constantly emitting light in CW mode, a mechanical filter is used to block the light from one of the LEDs.

[0055] Conventionally, there were no optical fibers or liquid light guides that could transmit light from 220nm to 2000nm with a single connection. However, as shown in Figure 5, by attaching multiple optical fibers or liquid light guides to multiple LED elements 1c and 1d with different wavelengths, it became possible to automatically irradiate them with light from 220nm to 2000nm. This is particularly effective for manufacturing lines.

[0056] Evaluating products flowing down a manufacturing line required irradiating them with multi-wavelength light for short periods. For example, it was necessary to irradiate them with more than ten different wavelengths per second. Depending on the LED wavelength, if the output was insufficient, it was sometimes necessary to irradiate the product for a relatively long time, for example, 100 msec, to evaluate it. In such cases, the switching time from one wavelength to the next was on the order of 10 msec, which was a drawback for current stepping motors. However, by taking output from multiple points, the travel time could be halved, for example, by using two points, reducing the wavelength exchange time and enabling high-speed line irradiation.

[0057] Figure 6 shows a mechanism for moving the optical fiber or liquid light guide 35 because, depending on the shape of the LED element, such as whether it is a flat plate type or a lens-type LED element 1 as shown in Figure 6, the light input surface 36 of the optical fiber or liquid light guide 35 may not be able to be set with a gap of the order of 0.1 to 0.2 mm on the surface of the LED element. The light input part 36 of the optical fiber or liquid light guide is held in the housing 34 by a ball bearing 37, and the optical fiber or liquid light guide 35 can be moved by a small amount by rotating the motor 38 and using a screw 39.

[0058] Figure 7 shows a Peltier element 30 (Laird Thermal Systems OTX08-18-F0-0505-11-W2.25) and a thermometer (TDK NTC thermistor NTCG163JF103FT1) 31 coupled below a detachable LED element 1. A rotating disc 3 (aluminum plate, 40 to 50 cm in diameter and 2 to 3 mm thick) with an insulating film 21 is covered with copper foil current introduction films 22a and 22b. The anode holder 33a and cathode holder 33b of the LED element are bonded to the copper foil by reflow solder. The cathode and anode holders 33a and 34b are made of conductive spring material, and the Peltier element 30 is bonded to the copper foil by 3M thermal conductive double-sided tape (VHR0601-03) 32a and 32b by expanding the spring material. The thermometer 31 is similarly connected with thermally conductive double-sided tape 32b. The surfaces of the anode electrode 19a and cathode electrode 19b of the LED element are in contact with the anode holder 33a and cathode holder 33b, respectively, enabling the LED element to emit light. When the lifespan of the LED element 1 is reached, it can be replaced with a new LED element by pushing the LED element 1 in the direction shown in the diagram.

[0059] In Figure 7, instead of the Peltier element 30, a small aluminum nitride heater with a built-in thermometer (Sakaguchi Electric Heating WALN-7) may be installed in the location of the Peltier element 30 in Figure 7. In this case, the thermometer 31 is built into the heater and is therefore not shown. The other configurations are the same as in the case of the Peltier element in Figure 7.

[0060] Figure 8 shows the wavelength output distribution of an LED. The LED is an NCSU434C from Nichia Corporation. The output peaks at 280 nm and is halved at approximately 5 nm.

[0061] Figure 9 is a diagram showing the shift in the LED emission peak wavelength due to temperature. At the start of emission, the temperature rises to several tens of degrees, resulting in a change in the peak wavelength of 1 to several nanometers or more. In applications where a multi-wavelength light source is used, such as the laser-based nonlinear crystal method described in Non-Patent Literature 3 (for inspection, analysis, and evaluation of samples in bio, pharmaceutical, semiconductor, etc.), the generated wavelength has a width of 1 nm, and stability of 1% or less is required. In conventional light sources using many inexpensive LEDs, the LED wavelength changes from the start of emission until it stabilizes (depending on the LED, it changes by 2 to 10 nm), and even after that, it remains unstable due to changes in room temperature, etc.

[0062] As shown in Figure 9, even during stable operation, a change of a few degrees in room temperature causes a change in wavelength, and a slight shift in the wavelength peak of emission results in output fluctuations. In visible LEDs, a change of a few degrees in room temperature results in a wavelength shift of 0.2 nm and an output fluctuation of 1%, but in far-infrared LEDs, the wavelength shift becomes 1 nm and the output fluctuation becomes 2-3%, making them unsuitable for applications requiring output fluctuations of less than 1% at a wavelength of 1 nm. With this invention, by using a Peltier element (30 in Figure 7) to maintain the LED's stability within 0.1 to 1 degree, it is possible to suppress wavelength fluctuations to less than 0.1% and output fluctuations to less than 0.5%. Furthermore, by measuring the output with a light sensor and applying feedback to stabilize the output, further output stabilization is possible.

[0063] By installing a heater with a built-in thermometer at the location of the Peltier element (30 in Figure 7) described above, the temperature of the LED element can be kept within 0.1 to 1 degree Celsius, making it possible to suppress the wavelength fluctuation and output fluctuation of the LED to within 0.1% and within 0.5%, respectively.

[0064] Figure 10 shows the relationship between the temperature and output of LED element 1. When the output of LED element 1 is high, the temperature reaches several tens of degrees. At the start of light emission of LED element 1, the temperature of LED element 1 rises and the output of LED element 1 decreases. After about 10 minutes, the temperature stabilizes and the output settles to within 1%. It takes more than 30 minutes from the start of light emission for the output to stabilize at 0.1%.

[0065] The temperature of LED element 1 is raised by applying a reverse voltage pulse to a Peltier element (30 in Figure 7) placed beneath the LED, matching the temperature of LED element 1 at its operating voltage, before LED element 1 emits light. Subsequently, while LED element 1 emits light, the temperature of LED element 1 is maintained at a steady state by the cooling and heating operation of the Peltier element. Figure 11 is a specific example of the initial stability of LED light emission using this method. An LED element with a wavelength of 660 nm is used, and the temperature is raised a few seconds beforehand. In this way, the initial stability of light emission can be greatly improved.

[0066] By replacing the Peltier element in Figure 7 with a heater, the stability of the initial stage of light emission can be significantly improved in a similar manner.

[0067] Figure 12 is an overview of the LED light source device 40. Outside air 42 is drawn in through a wire mesh 43 from a fan 41 that cools the inside of the LED light source device by air cooling. This air is divided into two parts; one part passes through holes 46 in the cooling section 45 below the Peltier element 44 and is drawn into the device. (Although the fan 41 and the cooling section 45 are shown separately in the figure, they are in contact). A thermometer is installed at the front of the device and is controlled to keep the temperature constant. The other part of the outside air is discharged to the outside 50 by passing through holes 48 in the aluminum fins 47 for cooling the Peltier element 44 and the wire mesh 49. In this way, even if the external temperature changes rapidly, the LED output and wavelength shift can be suppressed.

[0068] Figures 13 and 14 show the stability test during ON-OFF operation when the external air temperature changes, particularly when the air conditioner's room temperature is set to 28 degrees Celsius in summer. Figure 13 shows the fluctuation of light output when the temperature is controlled using the device shown in Figure 12, and Figure 14 shows the case when there is no temperature control. [Industrial applicability]

[0069] This invention is for applications such as inspection, testing, and characterization of semiconductor wafers or materials used in wafer manufacturing, and evaluation of products flowing through a production line by irradiating samples with high-speed, multi-wavelength light in semiconductor, bio, pharmaceutical, and chemical manufacturing lines. Furthermore, this invention is also for research and experimental applications outside of manufacturing lines, where multi-wavelength light is irradiated onto a sample to be measured, and the reflected and transmitted light is observed. [Explanation of Symbols]

[0070] 1 LED element 1a LED element to be replaced because it has reached the end of its lifespan. LED elements with different wavelengths: 1c and 1d 2 LED light-emitting part 3 Rotating Discs 4 Stepping motors 5. Replaceable and detachable retaining section for LED elements 5a, 5b Removable and retaining part for replacing LED elements that have reached the end of their lifespan. 6. Replacement LED elements (for stock) 6a Next, replace the new LED element 7 Replacement LED Box 8a,b,c Moving mechanism for the storage box of replacement LEDs 9a,b,c,d,e Replacement feed mechanism 10 Stackable boxes containing the same replacement LEDs 17, 17a,b Fiber optic or liquid light guide 19a,b Anode and cathode electrodes of LEDs 30 Peltier element or heater 31 Thermometer 33a, 33b Anode and cathode holding parts 35 Fiber optic or liquid light guide 36. Tip of optical fiber or liquid light guide 37 Ball bearings 38 Stepping motor 41. Fan for drawing in external air for cooling the device. 44 Peltier elements 45 Cooling section

Claims

1. An LED light source device having an LED holding part for detachably fixing an LED element, and an automatic mechanism for automatically pushing out the LED element from the detachable fixing part and replacing it with a new LED element.

2. The LED light source device described above has a mechanism for rotating the rotating disk, with multiple detachable LED holders for the LED elements fixed to a rotating disk.

3. The LED light source device described above has multiple LED elements of the same wavelength stacked together for each wavelength, and the LED light source device can automatically move the LED elements to the replacement location according to the wavelength of the LED element to be replaced.

4. The LED light source device described above is configured to automatically replace an LED element with a new one when the LED element reaches the end of its lifespan by measuring the light output of an externally installed device.

5. The LED light source device described above, characterized in that the light emitted from the LED element is extracted by a plurality of optical fibers or liquid light guides.

6. The LED light source device described above, comprising an optical fiber or liquid light guide moving part that allows adjustment of the distance between the input surface of the optical fiber or liquid light guide and the LED element.

7. The LED light source device described above, wherein a Peltier element and a thermometer are attached to the LED element, the LED element is heated before it emits light, and after it emits light, the temperature of the LED element is controlled to a predetermined temperature.

8. The LED light source device described above includes a heater and a thermometer attached to the LED element, and controls the current supplied to the heater to raise the temperature of the LED element before it emits light, and to bring the temperature of the LED element to a predetermined temperature at the same time as it emits light.

9. The LED light source device described above is characterized by attaching a Peltier element and a thermometer, or a heater and a thermometer, to the LED element, thereby raising the temperature of the LED element to the temperature at which it is emitting light, even when the LED element is not emitting light.

10. The LED light source device is characterized by being provided with an external cooling fan, a thermometer for measuring the temperature of the air entering from the fan, and a Peltier element for controlling the temperature of the air.

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