Inspection device for built-in thermistor chip assembly of optoelectronic device
By using the Wheatstone bridge resistance method in the thermistor detection device, the problem of the inability to detect the adequacy and performance of the thermistor solder before assembly is solved, and high-precision detection is achieved before assembly, which improves detection efficiency and reduces costs .
Patent Information
- Application Number
- CN202420442070.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-07
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-03-07
AI Technical Summary
The prior art cannot effectively detect the soldering sufficiency and performance of the thermistor before assembly, resulting in the incoming solder missing or dummy soldering difficult to inspect intuitively, affecting device performance, and can only be effectively tested after the device packaging is completed, adding materials and time consumption.
A check device with built-in the thermistor chip assembly of optoelectronic devices is designed, and the detection circuit is composed of a Wheatstone bridge, an operational amplifier, an ADC analog converter and a microprocessor. The thermistor is measured by the Wheatstone bridge resistance method. It can be precisely tested before assembly.
It realizes high-precision detection of the thermistor before assembly, avoids waste caused by failure after assembly, improves production testing efficiency, reduces costs, and supports rapid detection under normal temperature and variable temperature conditions.
Smart Images
Figure CN222145113U_ABST
Abstract
Description
Technical Field
[0001] The utility model discloses a thermistor inspection device, belongs to the technical field of thermistor inspection devices, and specifically relates to an inspection device for a thermistor chip component built into an optoelectronic device. Background Art
[0002] Thermistor is a sensor resistor whose resistance value changes with temperature. At present, it is not possible to effectively detect the effectiveness of thermistor when it is received. At present, our company often uses 14-pin and 8-pin tube shell assembly, and solders the thermistor to the TEC with solder. Figure 1 The picture shown is taken under a microscope. Figure 2 As shown in the figure, the thermistor is very small, with a size of 1mm×0.5mm, and cannot be directly measured by a multimeter. The positive and negative poles of the thermistor are connected to the 2 and 5 pins. The resistance value of the 2 and 5 pins can be tested to determine the quality of the thermistor at room temperature, but it cannot directly determine whether the thermistor is soldered. It may also be due to insufficient soldering and voids. However, the soldering sufficiency of the thermistor and the effectiveness of the thermistor under variable temperature conditions cannot be effectively detected before the cap is sealed. It can only be tested after the cap is sealed.
[0003] In the conventional production of SLD devices, thermistor is a key component. It is an electronic device that changes significantly with temperature. It belongs to NTC thermistor. Thermistor can be used to convert temperature into electrical quantity to realize digital monitoring and control of the temperature generated during the operation of SLD devices. However, it is a big problem to check the stability of thermistor, because thermistor does not operate independently, but works with cos and tec components. Through a lot of practice, it is found that there are the following three problems in the inspection and testing of thermistor:
[0004] 1. The size of the thermistor is only 0.5mm×1mm, and its resistance performance cannot be directly tested with a multimeter. The test result is only the resistance value at room temperature and is not indicative.
[0005] 2. In terms of technology, there is currently no direct and effective way to fully test thermistors and their solders during the packaging process. There may be leaks and cold solder joints between the solders, and they cannot be visually checked. Traditional inspection methods use a multimeter to test the resistance value between PIN2 and 5 to make judgments, which is relatively simple and unreliable.
[0006] 3. The adequacy of solder will also directly affect the function of the thermistor. The thermistor and the heat sink TEC are soldered together by soldering these components. The adequacy of solder also directly affects the performance of the device.
[0007] At present, the existing technology cannot directly determine the quality of these three issues. At present, thermistor inspection cannot be directly measured by a multimeter because thermistors are very small. They can only be tested by temperature cycling after the device is packaged. The performance of the thermistor can be determined by detecting the power change rate of the device during the temperature cycle. This increases the consumption of materials and increases the working hours. The thermistor is a small assembly part. When soldering is attached to the heat source during assembly, it can effectively reflect the temperature change and control the TEC problem.
[0008] However, there is no effective method to test the performance of thermistors at this stage. They can only be tested after assembly. Based on this demand, a method is needed to test thermistors before assembly. Select suitable thermistors with excellent performance. The quality of thermistors determines the quality of the device. Therefore, a technology that can detect thermistors before assembly is needed, which is also the purpose of the invention of this utility model. Utility Model Content
[0009] Purpose of the utility model: to provide an inspection device for thermistor chip components built into optoelectronic devices, so as to solve the above-mentioned problem that thermistor detection can only be done after the device is assembled to determine whether the thermistor is good or bad, and such detection is obviously very complicated and wastes materials. Since thermistors are small, it is very troublesome to detect them after assembly, and if they are unqualified, they need to be reassembled, which is quite time-consuming.
[0010] Technical solution: An inspection device for an optoelectronic device with a built-in thermistor chip assembly, the inspection device is composed of at least one detection circuit, a reference voltage regulator U1 and a microprocessor U5;
[0011] The detection circuit is composed of a first operational amplifier, a second operational amplifier, a differential amplifier, a Wheatstone bridge and an ADC analog converter;
[0012] The reference voltage regulator U1 is connected to the first operational amplifier to form a current source to provide a constant and precise current for the Wheatstone bridge. The input end of the Wheatstone bridge is connected to the output end of the first operational amplifier, and the output end is connected to the input end of the differential amplifier. The input end of the second operational amplifier is connected to the output end of the differential amplifier, and the output end is connected to the input end of the ADC analog converter. The output end of the ADC analog converter is externally connected to the microprocessor U5.
[0013] In a further embodiment, multiple detection circuits are connected in parallel, and the detection circuits are connected between the reference voltage source and the microprocessor.
[0014] In a further embodiment, the Wheatstone bridge is composed of a resistor R1, a resistor R2, a thermistor RT and an adjustable potentiometer RP1.
[0015] In a further embodiment, the detection circuit includes: capacitor C1, first operational amplifier U2A, resistor R1, resistor R2, thermistor RT, adjustable potentiometer RP1, resistor R10, resistor R3, resistor R4, resistor R5, resistor R6, differential amplifier U3, second operational amplifier U2B, resistor R7, capacitor C2, resistor R8, resistor R9, adjustable potentiometer RP2, ADC analog converter U4 and polarity capacitor C3;
[0016] The non-inverting input terminal of the first operational amplifier U2A is connected to the output terminal of the reference voltage regulator U1, the output terminal of the first operational amplifier U2A is simultaneously connected to one end of the capacitor C1, one end of the resistor R1, and one end of the resistor R2, the inverting output terminal of the first operational amplifier U2A is simultaneously connected to the other end of the capacitor C1, one end of the resistor R10, one end of the thermistor RT, one end of the adjustable potentiometer RP1, and the control terminal, one end of the resistor R3 is simultaneously connected to the other end of the resistor R2 and the other end of the adjustable potentiometer RP1, one end of the resistor R4 is simultaneously connected to the other end of the resistor R1 and the other end of the thermistor RT, the non-inverting input terminal of the differential amplifier U3 is simultaneously connected to the other end of the resistor R3 and one end of the resistor R5, and the inverting input terminal of the differential amplifier U3 is simultaneously connected to the other end of the resistor R3 and one end of the resistor R5. The output end of the differential amplifier U3 is connected to the other end of the resistor R4 and one end of the resistor R6, the output end of the differential amplifier U3 is also connected to the other end of the resistor R6 and one end of the resistor R7, the other end of the resistor R5 is grounded, the non-inverting input end of the second operational amplifier U2B is connected to the other end of the resistor R7, the inverting input end of the second operational amplifier U2B is simultaneously connected to one end of the capacitor C2, one end of the resistor R8 and one end of the resistor R9, the output end of the second operational amplifier U2B is simultaneously connected to the other end of the capacitor C2, the other end of the resistor R8 and the input end of the ADC analog converter U4, the other end of the resistor R9 is connected to one end of the adjustable potentiometer RP2, the other end of the adjustable potentiometer RP2 is grounded, one end of the polarity capacitor C3 is grounded, and the other end is connected to the ADC analog converter U4.
[0017] In a further embodiment, the Wheatstone bridge has an external interface, and the interface is connected to the OC1 pin and the OC2 pin of the thermistor RT of the Wheatstone bridge.
[0018] In a further embodiment, the differential amplifier U3 provides a differential output with an adjustable gain amplification factor for the Wheatstone bridge output, and the second operational amplifier U2B provides additional gain for the output of the differential amplifier U3, and the gain size is fine-tuned and calibrated using RP2.
[0019] In a further embodiment, the reference voltage of the reference voltage source U1 and the reference voltage of the ADC analog converter U4 are at the same potential point.
[0020] Beneficial effects: The utility model has high measurement accuracy, easy measurement circuit construction, convenient measurement, and can measure one, dozens or even dozens of devices at a time. The measurement data is highly visualized, and can monitor in real time and save data for archiving. Unqualified thermistors can be found quickly in both normal temperature measurement and variable temperature measurement schemes, improving production test efficiency. Moreover, the entire set of utility model technical solutions is easy to operate and maintain, low in cost, and relatively low in standby power consumption, which is cheaper and more efficient than existing sensor-based measurement equipment on the market. The utility model realizes the testing of thermistors before assembly, avoiding the waste of devices after assembly due to unqualified thermistors. Moreover, this invention can be tested in any process before the device is capped, which improves work efficiency and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 The utility model discloses a circuit principle diagram for accurately measuring a thermistor using a Wheatstone bridge method.
[0022] Figure 2 This is a schematic diagram of the simultaneous measurement of multiple thermistors of the utility model. DETAILED DESCRIPTION
[0023] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0024] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0025] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present utility model described below can be combined with each other as long as they do not conflict with each other.
[0026] An inspection device for a built-in thermistor chip assembly of an optoelectronic device, the inspection device comprising at least one detection circuit, a reference voltage regulator U1 and a microprocessor U5;
[0027] The detection circuit is composed of a first operational amplifier, a second operational amplifier, a differential amplifier, a Wheatstone bridge and an ADC analog converter;
[0028] The reference voltage regulator U1 is connected to the first operational amplifier to form a current source to provide a constant and precise current for the Wheatstone bridge. The input end of the Wheatstone bridge is connected to the output end of the first operational amplifier, and the output end is connected to the input end of the differential amplifier. The input end of the second operational amplifier is connected to the output end of the differential amplifier, and the output end is connected to the input end of the ADC analog converter. The output end of the ADC analog converter is externally connected to the microprocessor U5.
[0029] In one embodiment, Figure 1 to Figure 2 As shown, multiple detection circuits are connected in parallel, and the detection circuits are connected between the reference voltage source and the microprocessor.
[0030] In one embodiment, Figure 1 to Figure 2 As shown, the Wheatstone bridge is composed of a resistor R1, a resistor R2, a thermistor RT and an adjustable potentiometer RP1.
[0031] In one embodiment, Figure 1 to Figure 2 As shown, the detection circuit includes: capacitor C1, first operational amplifier U2A, resistor R1, resistor R2, thermistor RT, adjustable potentiometer RP1, resistor R10, resistor R3, resistor R4, resistor R5, resistor R6, differential amplifier U3, second operational amplifier U2B, resistor R7, capacitor C2, resistor R8, resistor R9, adjustable potentiometer RP2, ADC analog converter U4 and polarity capacitor C3;
[0032] The non-inverting input terminal of the first operational amplifier U2A is connected to the output terminal of the reference voltage regulator U1, the output terminal of the first operational amplifier U2A is simultaneously connected to one end of the capacitor C1, one end of the resistor R1, and one end of the resistor R2, the inverting output terminal of the first operational amplifier U2A is simultaneously connected to the other end of the capacitor C1, one end of the resistor R10, one end of the thermistor RT, one end of the adjustable potentiometer RP1, and the control terminal, one end of the resistor R3 is simultaneously connected to the other end of the resistor R2 and the other end of the adjustable potentiometer RP1, one end of the resistor R4 is simultaneously connected to the other end of the resistor R1 and the other end of the thermistor RT, the non-inverting input terminal of the differential amplifier U3 is simultaneously connected to the other end of the resistor R3 and one end of the resistor R5, and the inverting input terminal of the differential amplifier U3 is simultaneously connected to the other end of the resistor R3 and one end of the resistor R5. The output end of the differential amplifier U3 is connected to the other end of the resistor R4 and one end of the resistor R6, the output end of the differential amplifier U3 is also connected to the other end of the resistor R6 and one end of the resistor R7, the other end of the resistor R5 is grounded, the non-inverting input end of the second operational amplifier U2B is connected to the other end of the resistor R7, the inverting input end of the second operational amplifier U2B is simultaneously connected to one end of the capacitor C2, one end of the resistor R8 and one end of the resistor R9, the output end of the second operational amplifier U2B is simultaneously connected to the other end of the capacitor C2, the other end of the resistor R8 and the input end of the ADC analog converter U4, the other end of the resistor R9 is connected to one end of the adjustable potentiometer RP2, the other end of the adjustable potentiometer RP2 is grounded, one end of the polarity capacitor C3 is grounded, and the other end is connected to the ADC analog converter U4.
[0033] In one embodiment, Figure 1 to Figure 2 As shown, the Wheatstone bridge has an external interface, and the interface is connected to the OC1 pin and the OC2 pin of the thermistor RT of the Wheatstone bridge.
[0034] In one embodiment, Figure 1 to Figure 2As shown, the differential amplifier U3 provides a differential output with adjustable gain amplification factor for the Wheatstone bridge output, and the second operational amplifier U2B provides additional gain for the output of the differential amplifier U3. The gain size is fine-tuned and calibrated using RP2.
[0035] In one embodiment, Figure 1 to Figure 2 As shown, the reference voltage of the reference voltage source U1 and the reference voltage of the ADC analog converter U4 are at the same potential point.
[0036] The following is a detailed description of the test method of the present invention according to the embodiments;
[0037] At present, the detection of thermistors can only be done after the device is assembled to determine whether the thermistor is good or bad. Such detection is obviously very complicated and wastes materials. Since thermistors are small, it is very troublesome to detect them after assembly. If they are unqualified, they need to be reassembled, which is a waste of time.
[0038] Existing measurement solutions based on sensors are generally expensive, the test steps are cumbersome and not easy to operate, and only a single device can be tested at a time, and multiple groups of devices cannot be tested simultaneously. The comparison of multiple groups of test data is cumbersome, time-consuming and labor-intensive. Moreover, it is difficult to test in a variable temperature environment, and existing equipment that can be tested in a variable temperature environment is very rare and generally expensive. The utility model truly achieves high measurement accuracy, the measured experimental data is relatively true and reliable, and the accuracy of judging whether the thermistor to be tested is faulty is high. The accuracy of the test results under constant temperature and variable temperature bidirectional conditions can be above 90%.
[0039] The test method of the utility model is explained from three aspects
[0040] 1. Test under constant temperature. Choose to assemble the thermistor into the tube shell for testing. Select several thermistors and assemble them into the tube shell first. Do not assemble other accessories. Place them in a constant temperature box. Test the resistance of the thermistor at room temperature of 25℃. Collect data with a computer and draw a curve. If the resistance of the thermistor remains constant over time at a constant temperature, the thermistor is considered qualified. Otherwise, it is unqualified. The test device is shown in the figure below. Figure 1 As shown;
[0041] 2. Test under variable temperature. Also choose to assemble the thermistor into the tube shell first. Then put it into the temperature cycle box. As time changes, the temperature changes from low temperature to high temperature. Monitor the change of the thermistor R through PC, get the data, draw the curve, and analyze the image. If the resistance of the thermistor changes linearly with the change of temperature, the thermistor performance is qualified, otherwise it is unqualified.
[0042] The solution of measuring thermistors by the Wheatstone bridge resistance method has high measurement accuracy, easy measurement circuit construction, convenient measurement, and can measure one, dozens or even dozens of devices at a time. The measurement data is highly visualized, and real-time monitoring and data storage and archiving are possible. Unqualified thermistors can be found more quickly in both normal temperature measurement solutions and variable temperature measurement solutions, thereby improving production test efficiency. Moreover, the entire set of practical new technical solutions is easy to operate and maintain, has low cost, and relatively low standby power consumption, and is cheaper and more efficient than existing sensor-based measurement equipment on the market.
[0043] In one embodiment, expensive sensors are required for precision electronic measurements, and most of them are very expensive and usually cannot operate under low power consumption. Some devices also have complex signal conditioning. So how can we achieve low cost and simple circuits with high enough measurement accuracy, and meet the needs of daily rapid measurement or quick judgment of the quality of electronic components to be tested? The present utility model provides a set of practical solutions that meet the above-mentioned index requirements under this premise. The following will compare Figure 1 and Figure 2 :The technical route of accurately measuring thermistor circuit schematic diagram using the Wheatstone bridge method is explained.
[0044] The utility model adopts a Wheatstone bridge circuit, and its greatest measurement advantage is that it can accurately measure the resistance value without an accurate reference voltage source or a high impedance meter. The resistive Wheatstone bridge uses the differential voltage between VO+ and VO- as an analog output. Figure 1 T1 is a Wheatstone bridge circuit, where R1 and R2 are fixed resistance values, RT is a thermistor with an interface and is pluggable (in this utility model, it specifically refers to SOA and SLD optical communication devices used in the communication field, where the thermistor is directly packaged on the heat sink of the TEC heat dissipation inside the device. It is small in size and not easy to measure manually) RP1 is an adjustable potentiometer. The resistance of the RP1 potentiometer can be manually adjusted externally.
[0045] The reference voltage regulator U1 (LT1027) inputs +15V and outputs +5V. It is at the same potential point as the reference voltage Vref of the subsequent ADC analog converter U4 (LTC1292). With a stable reference voltage, the ADC analog-to-digital conversion channel can provide a more accurate conversion output. When the Wheatstone bridge accurately measures resistance, at least a 12-bit ADC analog converter must be guaranteed, the long-term temperature drift must be less than 1.5uV, and the ADC offset voltage must also be extremely low. Try to choose an ADC converter with an internal automatic zero calibration function. The noise level must be less than 1uVp-p, and the hardware circuit must meet the requirements of high common-mode suppression and digital noise filtering circuit design. The Wheatstone bridge measurement accuracy is very sensitive, with a wide range and high resolution to maximize the guarantee of obtaining more accurate numbers on the microprocessor. This is used to judge the quality of the thermistor to be measured.
[0046] The reference voltage source U1 and the first operational amplifier U2A form a current source to provide a constant and precise current value to the T1 Wheatstone bridge. The differential amplifier U3 provides a differential output with an adjustable gain amplification factor for the T1 Wheatstone bridge output. The second operational amplifier U2B provides additional gain for the output of the differential amplifier U3, and this gain can be fine-tuned and calibrated using the adjustable potentiometer RP2.
[0047] If the resistance value R1 in the T1 Wheatstone bridge is R2, and they are precision resistors made of the same material (wire-wound precision resistors with an accuracy of 0.01%), the thermistor RT is 10K at room temperature of 25°C. When the experimental environment is kept constant at 25°C, adjust the resistance value of the adjustable potentiometer RP1 so that the output of the T1 Wheatstone bridge circuit is 0V, that is, the voltage difference between VO+ and VO- is 0V. If R3=R4, R5=R6, the value of R6 / R4 is the amplification factor of the differential amplifier U3.
[0048] The thermistor RT is a negative temperature system resistor. As the ambient temperature rises (or the internal temperature of the device under test changes), the resistance value decreases. When the internal temperature of the device rises, the RT resistance value decreases, the voltage of VO- will decrease, the voltage of VO+ will remain unchanged, the voltage difference between VO+ and VO- will increase, and the output voltage of the differential amplifier U3 will amplify the voltage difference between VO+ and VO- according to a certain gain amplification factor. Then, the output of the second operational amplifier U2B fine-tuning calibration circuit is sent to the ADC analog-to-digital converter U4, and the ADC conversion output is sent to the microprocessor U5 through SPI communication. The host computer can monitor in real time the value of the change in the output voltage of the TI Wheatstone bridge caused by the change in the thermistor value at the current temperature.
[0049] Before measuring thermistors, the accuracy of experimental data can be ensured by calibration. The calibration steps are as follows: To ensure that the test environment temperature is a constant value, such as 25°C, take a standard thermistor (NTC negative temperature coefficient thermistor has a resistance of 10K at 25°C), insert the OC1 and OC2 pins, and adjust the RP1 potentiometer to make the differential output of the differential amplifier U3 0V, the second operational amplifier U2B gain amplifier output is also 0V, the ADC analog conversion U4 output value is also 0, and the value monitored by the microprocessor host computer is also 0. That is, at this time, the Wheatstone bridge reaches the balance point and satisfies the proportional relationship of R1 / RT=R2 / RP1. When the potentiometer RP1 is adjusted to a resistance value of 10K, the output of the Wheatstone bridge can just be 0V at this time, indicating that the thermistor RT is intact.
[0050] When in a variable temperature environment, the resistance value of thermistor RT changes with the rise and fall of temperature. To ensure that the resistance value of potentiometer RP1 remains unchanged, if the output voltage of the Wheatstone bridge also changes with temperature, the output voltage of the differential amplifier also changes proportionally, and the value of the ADC conversion output also changes proportionally. In this way, the change in resistance value of the thermistor with temperature change is reflected in the value of the change in output voltage of the Wheatstone bridge.
[0051] After calibration, the quality of the thermistor of the optoelectronic device to be measured can be judged. The measurement steps are as follows:
[0052] First, keep the ambient temperature to be tested constant at 25°C. Disconnect the pins of OC1 and OC2 from the standard thermistor, and connect the two ends of the thermistor of the optoelectronic device to be tested to OC1 and OC2 respectively (as mentioned above, pins 2 and 5 of the 14-pin and 8-pin optoelectronic devices are the access points for the thermistor). Measure whether the voltage at the output terminal TP1 of the differential amplifier U3 is 0V, or the digital size obtained through ADC analog-to-digital conversion. If the data obtained is close to 0V or equal to 0V, and is within the error range data given by the thermistor manufacturer, it can directly determine the quality of the thermistor inside the optoelectronic device. If the data exceeds the range, it can be preliminarily determined that there may be a problem with the thermistor.
[0053] Second, after the first step of measuring and judging that the thermistor is OK, the second step can be carried out to further judge whether the thermistor can work normally in a temperature-changing environment. The second step is in a variable temperature environment (generally in device manufacturers, during the assembly process of optoelectronic devices, the device will be subjected to high and low temperature cycle tests, and high and low temperature cycle box equipment will generally be used. The temperature change of the high and low temperature cycle box equipment is a linear rise and fall of the temperature according to the corresponding time and temperature). Since the output value of the ADC converter U4 can only change between 0-4095 (12-bit precision ADC converter), the corresponding input voltage is 0-5V. Therefore, the output voltage value of the Wheatstone bridge can only start from 0V. Therefore, when the temperature of the high and low temperature cycle box changes in the range of 0-70℃, the Wheatstone bridge is adjusted to the balance point of the thermistor RT and the potentiometer RP1 when the temperature is 0℃, that is, the differential output is 0V voltage. When the temperature gradually rises from 0℃ to 70℃, the voltage output by the bridge also changes from 0V to a certain voltage value. According to the temperature change curve, the bridge output voltage change and the ADC analog-to-digital conversion value curve correspond. The value obtained by ADC in this high and low temperature cycle process is compared with the value curve of the standard thermistor under the same environment. According to the degree of fit of the curve, the quality of the thermistor to be tested can be judged. It is also very convenient, and no personnel are required to be on duty during the measurement process. The host computer program can be used for data comparison, screening and identification (the utility model does not discuss the specific program code, but only measures and outputs the data of the thermistor to be tested changing with the ambient temperature).
[0054] The above tests can be performed on thermistors of optoelectronic devices alone, or on multiple thermistors of optoelectronic devices together to form 8 channels, 16 channels, etc. Thermistors of multiple optoelectronic devices can be measured and judged at one time, and the test data can be recorded for backup and archiving.
[0055] The same principle and the same test method can be used to test thermistors of multiple optoelectronic devices in the same high and low temperature cycle box. The test circuit schematic is as follows Figure 2 This test solution can test multiple components at one time, saving efficiency. In addition, under the same environmental conditions, the measured thermistor curves can be compared with each other to select the best performance index data of the device to the greatest extent.
[0056] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention of the utility model.
Claims
1. An inspection device for an optoelectronic device with a built-in thermistor chip assembly, characterized in that: The inspection device is composed of at least one detection circuit, a reference voltage source U1 and a microprocessor U5; The detection circuit is composed of a first operational amplifier, a second operational amplifier, a differential amplifier, a Wheatstone bridge and an ADC analog converter; The reference voltage regulator U1 is connected to the first operational amplifier to form a current source to provide a constant and precise current for the Wheatstone bridge. The input end of the Wheatstone bridge is connected to the output end of the first operational amplifier, and the output end is connected to the input end of the differential amplifier. The input end of the second operational amplifier is connected to the output end of the differential amplifier, and the output end is connected to the input end of the ADC analog converter. The output end of the ADC analog converter is externally connected to the microprocessor U5.
2. The inspection device for an optoelectronic device with a built-in thermistor chip assembly according to claim 1, characterized in that: The multi-channel detection circuits are connected in parallel, and the detection circuits are connected between the reference voltage source and the microprocessor.
3. The inspection device for an optoelectronic device with a built-in thermistor chip assembly according to claim 1, characterized in that: The Wheatstone bridge is composed of a resistor R1, a resistor R2, a thermistor RT and an adjustable potentiometer RP1.
4. The inspection device for an optoelectronic device with a built-in thermistor chip assembly according to claim 1, characterized in that: The detection circuit includes: capacitor C1, first operational amplifier U2A, resistor R1, resistor R2, thermistor RT, adjustable potentiometer RP1, resistor R10, resistor R3, resistor R4, resistor R5, resistor R6, differential amplifier U3, second operational amplifier U2B, resistor R7, capacitor C2, resistor R8, resistor R9, adjustable potentiometer RP2, ADC analog converter U4 and polarity capacitor C3; The non-inverting input terminal of the first operational amplifier U2A is connected to the output terminal of the reference voltage regulator U1, the output terminal of the first operational amplifier U2A is simultaneously connected to one end of the capacitor C1, one end of the resistor R1, and one end of the resistor R2, the inverting output terminal of the first operational amplifier U2A is simultaneously connected to the other end of the capacitor C1, one end of the resistor R10, one end of the thermistor RT, one end of the adjustable potentiometer RP1, and the control terminal, one end of the resistor R3 is simultaneously connected to the other end of the resistor R2 and the other end of the adjustable potentiometer RP1, one end of the resistor R4 is simultaneously connected to the other end of the resistor R1 and the other end of the thermistor RT, the non-inverting input terminal of the differential amplifier U3 is simultaneously connected to the other end of the resistor R3 and one end of the resistor R5, and the inverting input terminal of the differential amplifier U3 is simultaneously connected to the other end of the resistor R3 and one end of the resistor R5. The output end of the differential amplifier U3 is connected to the other end of the resistor R4 and one end of the resistor R6, the output end of the differential amplifier U3 is also connected to the other end of the resistor R6 and one end of the resistor R7, the other end of the resistor R5 is grounded, the non-inverting input end of the second operational amplifier U2B is connected to the other end of the resistor R7, the inverting input end of the second operational amplifier U2B is simultaneously connected to one end of the capacitor C2, one end of the resistor R8 and one end of the resistor R9, the output end of the second operational amplifier U2B is simultaneously connected to the other end of the capacitor C2, the other end of the resistor R8 and the input end of the ADC analog converter U4, the other end of the resistor R9 is connected to one end of the adjustable potentiometer RP2, the other end of the adjustable potentiometer RP2 is grounded, one end of the polarity capacitor C3 is grounded, and the other end is connected to the ADC analog converter U4.
5. The inspection device for an optoelectronic device with a built-in thermistor chip assembly according to claim 3, characterized in that: The Wheatstone bridge external interface is connected to the OC1 pin and the OC2 pin of the thermistor RT of the Wheatstone bridge.
6. The inspection device for an optoelectronic device with a built-in thermistor chip assembly according to claim 4, characterized in that: The differential amplifier U3 provides a differential output with an adjustable gain amplification factor for the Wheatstone bridge output, and the second operational amplifier U2B provides additional gain for the output of the differential amplifier U3. The gain size is fine-tuned and calibrated using RP2.
7. The inspection device for an optoelectronic device with a built-in thermistor chip assembly according to claim 4, characterized in that: The reference voltage of the reference voltage regulator U1 and the reference voltage of the ADC analog converter U4 are at the same potential point.