Method and apparatus for inspecting light-emitting device

Abstract

To provide an inspection method for a light-emitting device and an inspection device for a light-emitting device that can determine deterioration of a light-emitting device which has a bypass current resistor parallel with an LED.SOLUTION: An inspection method for a light-emitting device uses an operational amplifier OA1 which has its inverted input terminal and output terminal electrically connected to each other. The inspection method also uses a first terminal TL1, a second terminal TL3, and a third terminal TL3 for electrically connecting the inverted input terminal or a non-inverted input terminal of the operational amplifier OA1. The inspection method comprises: connecting the first terminal TL1 to an anode terminal of a light-emitting element LED 1; and connecting the second terminal TL2 to a cathode terminal of the light-emitting element LED 1. The inspection method comprises connecting the third terminal TL3 so that a bypass resistor RD1 is sandwiched between the second terminal TL2 and third terminal TL3. The inspection method measures the voltage between the anode terminal and cathode terminal of the light-emitting element LED 1 while letting a constant current flow to the light-emitting element LED 1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The technical field of the present specification relates to a method and apparatus for inspecting a light emitting device. [Background technology]

[0002] When manufacturing light-emitting devices equipped with LEDs, the deterioration of the LEDs is sometimes determined by passing a minute current through the LED on the circuit board on which the LED is mounted and measuring the voltage between both terminals of the LED.

[0003] Patent Document 1 discloses an inspection method in which a first constant current of 1 μA or less is passed in the forward direction of an LED to measure a first voltage, and a second constant current about 10 times the first constant current is passed in the forward direction of the LED to measure a second voltage. A light emitting device whose first voltage is equal to or greater than a predetermined reference voltage is judged to be suitable, and then a light emitting device whose difference between the first voltage and the second voltage is within a predetermined range is judged to be suitable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-170311 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, semiconductor switches are sometimes used to control LEDs. Semiconductor switches can generate a leakage current of about several μA. This leakage current causes the LED to light slightly. To prevent this slight lighting of the LED, a bypass resistor is sometimes provided in parallel with the LED. When inspecting such a light-emitting device, a bypass current flows through the bypass resistor, and the current flowing through the LED deviates from the constant current by the amount of the bypass current.

[0006] In order to prevent bypass current, a diode is sometimes placed in series with the LED in the light-emitting device. However, this diode is only necessary for this deterioration test, and is not required when the light-emitting device is in use. The voltage drop caused by the diode is relatively small. However, the presence of a diode in the light-emitting device increases the driving voltage, increases power consumption, and complicates the circuit board.

[0007] The problem to be solved by the technology of this specification is to provide a method and apparatus for inspecting a light emitting device that can determine the deterioration of a light emitting device having a bypass current resistor in parallel with an LED. [Means for solving the problem]

[0008] The inspection method of the light emitting device in the first aspect is a method for inspecting a light emitting device having a light emitting element having an anode terminal and a cathode terminal, a first resistor connected in series with the light emitting element, and a bypass resistor connected in parallel with the light emitting element. In this method, an operational amplifier having an inverting input terminal and an output terminal in conduction is used, and a first terminal in conduction with the constant current source positive terminal of the constant current source and the voltmeter positive terminal of the voltmeter, a second terminal in conduction with the constant current source negative terminal of the constant current source and the voltmeter negative terminal of the voltmeter, and a third terminal in conduction with the inverting input terminal or the non-inverting input terminal of the operational amplifier are used. The first terminal is connected to the anode terminal of the light emitting element. The second terminal is connected to the cathode terminal of the light emitting element. The third terminal is connected so that at least a part of the first resistor or the bypass resistor is sandwiched between the first terminal or the second terminal and the third terminal. The voltage between the anode terminal and the cathode terminal of the light emitting element is measured while a constant current is flowing through the light emitting element.

[0009] In this light-emitting device inspection method, the voltage across the terminals of the light-emitting element is measured while a constant current is passed through the light-emitting element, while controlling the voltage across the terminals of the bypass resistor to be almost zero. Since almost no current flows through the bypass resistor during measurement, the current flowing through the light-emitting element is almost equal to the constant current passed by the constant current source. Therefore, by using this light-emitting device inspection method, it is possible to accurately determine the deterioration of a light-emitting element having a bypass resistor for bypassing leakage current. Effect of the Invention

[0010] Provided herein is a method and apparatus for inspecting a light emitting device that can determine degradation of a light emitting device having a bypass current resistor in parallel with an LED. [Brief description of the drawings]

[0011] [Figure 1] 2 is a circuit diagram of a light-emitting device DV1 to be inspected in the first embodiment. FIG. [Diagram 2] 1 is a circuit diagram of an inspection apparatus 100 for a light emitting device DV1 according to a first embodiment. [Diagram 3] 1 is a circuit diagram (part 1) illustrating a method for inspecting the light emitting device DV1 of the first embodiment. [Figure 4] 11 is a circuit diagram (part 2) illustrating a method for testing the light emitting device DV1 of the first embodiment. FIG. [Diagram 5] FIG. 1 is a circuit diagram (part 1) showing a conventional method for inspecting a light emitting device. [Figure 6] FIG. 13 is a circuit diagram (part 2) showing a conventional method for inspecting a light emitting device. [Figure 7] 13 is a circuit diagram showing a method for inspecting the light emitting device DV1 of the second embodiment. FIG. [Figure 8] 13 is a circuit diagram of a light-emitting device DV2 to be inspected according to the third embodiment. FIG. [Figure 9] FIG. 11 is a circuit diagram showing a method for inspecting the light emitting device DV2 of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, specific embodiments will be described with reference to the drawings, taking an inspection method for a light emitting device and an inspection device for a light emitting device as examples. However, the technology of this specification is not limited to these embodiments. In the embodiment, the potential difference between the terminals at both ends of a specified resistor is controlled to be zero, but in reality, it is not completely zero, and an extremely small potential difference may occur.

[0013] (First embodiment) 1. Light emitting device 1 is a circuit diagram of a light emitting device DV1 to be inspected in the first embodiment. The light emitting device DV1 includes a light emitting element LED1, a resistor R1, a bypass resistor RD1, and a semiconductor switch SW1.

[0014] The light emitting element LED1 is a semiconductor light emitting element that emits light when a voltage is applied to it The light emitting element LED1 has an anode terminal TM1 and a cathode terminal TM2.

[0015] The resistor R1 is an electrical resistor connected in series with the light-emitting element LED1. The resistor R1 is not limited to a single element, but includes the resistance of a plurality of elements connected in series with the light-emitting element LED1.

[0016] The bypass resistor RD1 is an electrical resistor for bypassing leakage current caused by the semiconductor switch SW1. The bypass resistor RD1 is connected in parallel with the light-emitting element LED1 and the resistor R1. The bypass resistor RD1 is not limited to a single element, but includes the resistance of a plurality of elements connected in parallel with the light-emitting element LED1 and the resistor R1.

[0017] The semiconductor switch SW1 is a switch for applying a voltage to the light-emitting element LED1. The semiconductor switch SW1 is connected in series with the light-emitting element LED1, resistor R1, and bypass resistor RD1. The semiconductor switch SW1 may be disposed in a position different from that shown in FIG. 1 as long as it is connected in series with the light-emitting element LED1. In the subsequent figures, the semiconductor switch SW1 may be omitted.

[0018] The light emitting device DV1 has a terminal TM3. A resistor R1 is disposed between the anode terminal TM1 and the terminal TM3. A bypass resistor RD1 is disposed between the cathode terminal TM2 and the terminal TM3.

[0019] 2. Light-emitting device inspection equipment 2 is a circuit diagram of an inspection apparatus 100 for the light emitting device DV1 of the first embodiment. The inspection apparatus 100 includes a constant current source A1, a voltmeter VM1, a positive voltage power supply BP1, a negative voltage power supply BM1, an operational amplifier OA1, a first terminal TL1, a second terminal TL2, and a third terminal TL3.

[0020] The constant current source A1 is a current source for supplying a constant current to an element between the first terminal TL1 and the second terminal TL2. The constant current source A1 has a constant current source positive terminal that is in electrical communication with the first terminal TL1, and a constant current source negative terminal that is in electrical communication with the second terminal TL2. In practice, the constant current source A1 supplies a constant current between the anode terminal TM1 and the cathode terminal TM2 of the light emitting device DV1. The direction of the current supplied by the constant current source A1 is from the anode terminal TM1 to the cathode terminal TM2. In other words, a current I flows from the anode to the cathode of the light emitting element LED1. LED flows in the forward direction. Current I LED is, for example, 0.1 μA or more and 10 μA or less.

[0021] The voltmeter VM1 is a measuring instrument for measuring the voltage between the first terminal TL1 and the second terminal TL2. The voltmeter VM1 has a voltmeter positive terminal that is electrically connected to the first terminal TL1 and a voltmeter negative terminal that is electrically connected to the second terminal TL2. In practice, the voltmeter VM1 measures the voltage between the anode terminal TM1 and the cathode terminal TM2 of the light emitting device DV1. This allows the voltmeter VM1 to measure the voltage between the terminals of the light emitting element LED1.

[0022] Operational amplifier OA1 has a positive power supply terminal, a negative power supply terminal, a non-inverting input terminal, an inverting input terminal, and an output terminal.

[0023] The positive power supply terminal is connected to a positive voltage power supply BP1, and the negative power supply terminal is connected to a negative voltage power supply BM1.

[0024] The non-inverting input terminal is electrically connected to the third terminal TL3, and the inverting input terminal and the output terminal are electrically connected to the second terminal TL2.

[0025] The operational amplifier OA1 configures a voltage follower circuit, i.e., a negative feedback circuit that connects the inverting input terminal and the output terminal is realized.

[0026] The positive voltage power supply BP1 inputs a positive voltage to the positive power supply terminal of the operational amplifier OA1. The positive voltage power supply BP1 is electrically connected to the positive power supply terminal of the operational amplifier OA1.

[0027] The negative voltage power supply BM1 inputs a negative voltage to the negative power supply terminal of the operational amplifier OA1. The negative voltage power supply BM1 is electrically connected to the negative power supply terminal of the operational amplifier OA1.

[0028] The first terminal TL1 is a terminal for connection to the anode terminal TM1 of the light emitting element LED1. The first terminal TL1 is electrically connected to the constant current source positive terminal of the constant current source A1 and the voltmeter positive terminal of the voltmeter VM1.

[0029] The second terminal TL2 is a terminal for connection to the cathode terminal TM2 of the light emitting element LED1. The second terminal TL2 is electrically connected to the constant current source negative terminal of the constant current source A1 and the voltmeter negative terminal of the voltmeter VM1.

[0030] The third terminal TL3 is a terminal for establishing electrical continuity with the inverting input terminal or the non-inverting input terminal of the operational amplifier OA1.

[0031] The inspection apparatus 100 is capable of connecting the third terminal TL3 so that at least a portion of the resistor R1 or the bypass resistor RD1 is sandwiched between the first terminal TL1 or the second terminal TL2 and the third terminal TL3.

[0032] 3. Inspection method for light-emitting device 3 is a circuit diagram (part 1) showing a method for inspecting the light emitting device DV1 of the first embodiment. As shown in FIG.

[0033] The first terminal TL1 is electrically connected to the constant current source positive terminal of the constant current source A1 and the voltmeter positive terminal of the voltmeter VM1, while the second terminal TL2 is electrically connected to the constant current source negative terminal of the constant current source A1 and the voltmeter negative terminal of the voltmeter VM1.

[0034] An operational amplifier OA1 that configures a voltage follower is used. The non-inverting input terminal of the operational amplifier OA1 is connected to the third terminal TL3. The inverting input terminal and the output terminal of the operational amplifier OA1 are connected to the second terminal TL2. In this manner, the third terminal is connected so that the bypass resistor RD1 is disposed between the second terminal TL2 and the third terminal TL3.

[0035] Since a voltage follower is configured by negative feedback, the potential of the inverting input terminal of the operational amplifier OA1 is equal to the potential of the non-inverting input terminal of the operational amplifier OA1 in principle, and therefore the potential difference between the second terminal TL2 and the third terminal TL3 is zero within the accuracy of the negative feedback.

[0036] The first terminal TL1 is connected to the anode terminal TM1 of the light emitting element LED1. The second terminal TL2 is connected to the cathode terminal TM2 of the light emitting element LED1. The third terminal TL3 is disposed so as to sandwich the resistor R1 between the third terminal TL3 and the first terminal TL1.

[0037] The positive terminal of the bypass resistor RD1 is connected to the third terminal TL3, and the negative terminal of the bypass resistor RD1 is connected to the second terminal TL2. At this time, the potentials at both ends of the bypass resistor RD1 are equal. That is, no voltage is applied to the bypass resistor RD1, and no current flows through the bypass resistor RD1.

[0038] 4 is a circuit diagram (part 2) showing a method for inspecting the light emitting device DV1 of the first embodiment. In FIG. 4, a current flowing through the circuit is shown. As shown in FIG. 4, a constant current source A1 flows a constant current I1. As a result, a device current I LED At this time, the resistor R1 and the bypass resistor RD1 are connected in parallel to the light emitting element LED1. The current flowing through the resistor R1 and the bypass resistor RD1 is virtually expressed as a current I R Let us assume that.

[0039] The above current satisfies the following equation: I LED = I1 - I R ………(1)

[0040] Here, the voltage across the bypass resistor RD1 is zero. Therefore, no current flows through the bypass resistor RD1. Also, no current flows through the resistor R1. Therefore, the current I R is zero. This gives us the following: I LED = I1 ………(2)

[0041] In this case, a desired constant current I1 can be applied to the light-emitting element LED1. That is, while applying the constant current I1 to the light-emitting element LED1, the voltage between the terminals on both ends of the light-emitting element LED1 can be measured.

[0042] If the voltage of the light-emitting element LED1 measured by the voltmeter VM1 is equal to or higher than a predetermined threshold voltage, the light-emitting element LED1 is determined to be a non-defective product. If the voltage of the light-emitting element LED1 measured by the voltmeter VM1 is less than a predetermined threshold voltage, the light-emitting element LED1 is determined to be a defective product. Here, a non-defective product means a light-emitting element that is not deteriorated and emits light appropriately. In this way, the inspection device 100 can accurately measure the voltage of the light-emitting element LED1.

[0043] In the first embodiment, while controlling the potential difference between both terminals of the bypass resistor RD1 to be zero, a constant current source A1 flows a constant current between the anode terminal TM1 and the cathode terminal TM2 of the light-emitting element LED1, while a voltmeter VM1 measures the voltage between the anode terminal TM1 and the cathode terminal TM2 of the light-emitting element LED1.

[0044] 4. Comparison with conventional technology 4-1. Conventional case FIG. 5 is a circuit diagram (part 1) showing a conventional method for inspecting a light-emitting device. In this case, the current I R is not zero, and equation (2) does not hold. Therefore, the current I1 flowing from the constant current source A1 does not correspond to the voltage measured by the voltmeter VM1. In other words, the voltage of the light-emitting element LED1 cannot be measured accurately.

[0045] 4-2. Conventional case (diode) FIG. 6 is a circuit diagram (part 2) showing a conventional method for inspecting a light-emitting device. In this case, a diode D1 is arranged in series with the light-emitting element LED1. Therefore, equation (2) holds. However, diode D1 is an element that is only necessary during this inspection. It is not necessary when the light-emitting device is in use. The voltage drop due to diode D1 is about 0.7V. The presence of diode D1 in light-emitting device DV1 increases the drive voltage, increases power consumption, and complicates the circuit board.

[0046] 5. Effects of the First Embodiment The inspection method for the light emitting device DV1 of the first embodiment uses an inspection device 100. With this, the voltage across the terminals of the light emitting element LED1 is measured while a constant current is passed through the light emitting element LED1, while controlling the voltage across the terminals of the bypass resistor RD1 to zero. During the measurement, since no current flows through the bypass resistor RD1, the current flowing through the light emitting element LED1 is a constant current I1. This makes it possible to accurately determine the deterioration of the light emitting element LED1 having a bypass resistor for bypassing leakage current.

[0047] 6. Variations 6-1. Terminal connection status As described above, the potential of the non-inverting input terminal and the potential of the inverting input terminal are controlled to be equal. Therefore, the non-inverting input terminal and the inverting input terminal may be interchanged. That is, in FIG. 3, the non-inverting input terminal of the operational amplifier OA1 may be connected to the second terminal TL2, and the inverting input terminal of the operational amplifier OA1 may be connected to the third terminal TL3. In this way, the third terminal is connected so that the bypass resistor RD1 is disposed between the second terminal TL2 and the third terminal TL3.

[0048] 6-2. Grounding Any point of the inspection device 100 may be grounded.

[0049] 6-3. Potential difference The potential difference between both terminals of the bypass resistor RD1 may be controlled to be −100 μV or more and 100 μV or less.

[0050] Combinations The above modifications may be combined.

[0051] Second embodiment A second embodiment will be described. The light emitting element LED1 and the inspection device 100 to be inspected in the second embodiment are similar to those in the first embodiment. Therefore, only the points different from the first embodiment will be described.

[0052] 1. Inspection method for light-emitting devices 7 is a circuit diagram showing a method for inspecting the light emitting device DV1 of the second embodiment. As shown in FIG. 7, an inspection device 100 is used. The connection state of the constant current source A1 and the voltmeter VM1 is the same as in the first embodiment. The connection state of the operational amplifier OA1 is different from that in the first embodiment.

[0053] The non-inverting input terminal of the operational amplifier OA1 is connected to the first terminal TL1. The inverting input terminal and the output terminal of the operational amplifier OA1 are connected to the third terminal TL3. In this manner, the third terminal is connected so that the resistor R1 is disposed between the first terminal TL1 and the third terminal TL3.

[0054] Therefore, a current I flows through resistor R1 and bypass resistor RD1. R is not flowing.

[0055] 2. Effects of the Second Embodiment The method for inspecting the light emitting device DV1 of the second embodiment uses an inspection device 100. With this, the voltage across the terminals of the light emitting element LED1 is measured while a constant current is passed through the light emitting element LED1, while controlling the voltage across the terminals of the resistor R1 to zero. During the measurement, since no current flows through the resistor R1, the current flowing through the light emitting element LED1 is a constant current I1. This makes it possible to accurately determine the deterioration of the light emitting element LED1, which has a bypass resistor for bypassing leakage current.

[0056] 3. Variations 3-1. Terminal connection status The non-inverting input terminal and the inverting input terminal may be interchanged. That is, in FIG. 7, the non-inverting input terminal of the operational amplifier OA1 may be connected to the third terminal TL3, and the inverting input terminal of the operational amplifier OA1 may be connected to the first terminal TL1. In this way, the third terminal is connected so that the resistor R1 is disposed between the first terminal TL1 and the third terminal TL3.

[0057] (Third embodiment) A third embodiment will be described. The inspection device 100 used for inspection in the second embodiment is similar to that in the first embodiment. Therefore, only the points different from the first embodiment will be described.

[0058] 1. Light emitting device 8 is a circuit diagram of a light emitting device DV2 to be inspected in the third embodiment. The light emitting device DV2 includes a light emitting element LED1, a resistor R1, bypass resistors RD2 and RD3, and a semiconductor switch SW1.

[0059] The bypass resistors RD2 and RD3 are bypass resistors for bypassing leakage current caused by the semiconductor switch SW1. The bypass resistors RD2 and RD3 are resistance components connected in parallel to the light-emitting element LED1. The bypass resistors RD2 and RD3 are not limited to a single element, but include the resistance of multiple elements connected in parallel to the light-emitting element LED1.

[0060] The bypass resistor RD2 and the bypass resistor RD3 are connected in series. The bypass resistor RD2 is disposed closer to the anode side than the bypass resistor RD3. The magnitude relationship between the electric resistance value of the bypass resistor RD2 and the electric resistance value of the bypass resistor RD3 may be any.

[0061] Bypass resistors RD2 and RD3 are connected in series with resistor R1.

[0062] 2. Inspection method for light-emitting devices 9 is a circuit diagram showing a method for inspecting a light emitting device DV2 according to the third embodiment. As shown in FIG. 9, an inspection device 100 is used. The connection state of a constant current source A1 and a voltmeter VM1 is the same as in the first embodiment. The connection state of an operational amplifier OA1 is different from that in the first embodiment.

[0063] The non-inverting input terminal of the operational amplifier OA1 is connected to the first terminal TL1. The inverting input terminal and the output terminal of the operational amplifier OA1 are connected to the third terminal TL3. In this manner, the third terminal is connected so that the bypass resistor RD2 is disposed between the first terminal TL1 and the third terminal TL3.

[0064] As a result, no current flows through resistor R1, and a current I flows through bypass resistors RD2 and RD3. R is not flowing.

[0065] 3. Effects of the Third Embodiment The inspection method for the light emitting device DV2 of the third embodiment uses an inspection device 100. With this, the voltage across the terminals of the light emitting element LED1 is measured while a constant current is passed through the light emitting element LED1, while controlling the voltage across the terminals of the bypass resistor RD2 to zero. During the measurement, since no current flows through the bypass resistor RD2, the current flowing through the light emitting element LED1 is a constant current I1. This makes it possible to accurately determine the deterioration of the light emitting element LED1 having a bypass resistor for bypassing leakage current.

[0066] 4. Variations 4-1. Terminal connection status The non-inverting input terminal and the inverting input terminal may be interchanged. That is, in FIG. 9, the non-inverting input terminal of the operational amplifier OA1 may be connected to the third terminal TL3, and the inverting input terminal of the operational amplifier OA1 may be connected to the first terminal TL1. In this manner, the third terminal is connected so that the bypass resistor RD2 is disposed between the first terminal TL1 and the third terminal TL3.

[0067] 4-2.Resistor The non-inverting input terminal of the operational amplifier OA1 may be connected to the second terminal TL2, and the inverting input terminal and the output terminal of the operational amplifier OA1 may be connected to the third terminal TL3. In this manner, the third terminal is connected so that the bypass resistor RD3 is disposed between the second terminal TL2 and the third terminal TL3.

[0068] The non-inverting input terminal of the operational amplifier OA1 may be connected to the third terminal TL3, and the inverting input terminal and the output terminal of the operational amplifier OA1 may be connected to the second terminal TL2.

[0069] (Additional Note) The inspection method of the light emitting device in the first aspect is a method for inspecting a light emitting device having a light emitting element having an anode terminal and a cathode terminal, a first resistor connected in series with the light emitting element, and a bypass resistor connected in parallel with the light emitting element. In this method, an operational amplifier having an inverting input terminal and an output terminal in conduction is used, and a first terminal in conduction with the constant current source positive terminal of the constant current source and the voltmeter positive terminal of the voltmeter, a second terminal in conduction with the constant current source negative terminal of the constant current source and the voltmeter negative terminal of the voltmeter, and a third terminal in conduction with the inverting input terminal or the non-inverting input terminal of the operational amplifier are used. The first terminal is connected to the anode terminal of the light emitting element. The second terminal is connected to the cathode terminal of the light emitting element. The third terminal is connected so that at least a part of the first resistor or the bypass resistor is sandwiched between the first terminal or the second terminal and the third terminal. The voltage between the anode terminal and the cathode terminal of the light emitting element is measured while a constant current is flowing through the light emitting element.

[0070] In the method for inspecting a light emitting device according to the second aspect, the third terminal is connected so as to place a bypass resistor between the second terminal and the third terminal.

[0071] In a method for inspecting a light emitting device according to a third aspect, the third terminal is connected so as to place a first resistor between the first terminal and the third terminal.

[0072] In a fourth aspect of the method for testing a light emitting device, the bypass resistor of the light emitting device includes a first bypass resistor and a second bypass resistor connected in series with the first bypass resistor, and the third terminal is connected so as to dispose the first bypass resistor between the first terminal and a third terminal.

[0073] In a fifth aspect of the method for testing a light emitting device, the bypass resistor of the light emitting device includes a first bypass resistor and a second bypass resistor connected in series with the first bypass resistor, and the third terminal is connected so as to dispose the second bypass resistor between the second terminal and a third terminal.

[0074] In a sixth aspect of the method for inspecting a light-emitting device, the light-emitting device includes a light-emitting element, a first resistor connected in series with the light-emitting element, and a bypass resistor connected in parallel with the light-emitting element. In this method, a voltage between an anode terminal and a cathode terminal of the light-emitting element is measured while a constant current is applied to the light-emitting element, while controlling a potential difference in at least a portion of the first resistor or the bypass resistor to be between −100 μV and 100 μV.

[0075] In a seventh aspect of the method for inspecting a light-emitting device, the light-emitting device includes a light-emitting element, a first resistor connected in series with the light-emitting element, and a bypass resistor connected in parallel with the light-emitting element. In this method, a voltage between an anode terminal and a cathode terminal of the light-emitting element is measured while a constant current is applied to the light-emitting element, while controlling a potential difference in at least a portion of the first resistor or the bypass resistor to be zero.

[0076] An inspection device for a light emitting device according to an eighth aspect inspects a light emitting device having a light emitting element having an anode terminal and a cathode terminal, a first resistor connected in series with the light emitting element, and a bypass resistor connected in parallel with the light emitting element. The inspection device has a first terminal for connecting with the anode terminal of the light emitting element, a second terminal for connecting with the cathode terminal of the light emitting element, a third terminal, a constant current source for passing a constant current between the first terminal and the second terminal, a voltmeter for measuring a voltage between the first terminal and the second terminal, and an operational amplifier. The constant current source has a constant current source positive terminal that is in conduction with the first terminal, and a constant current source negative terminal that is in conduction with the second terminal. The voltmeter has a voltmeter positive terminal that is in conduction with the first terminal, and a voltmeter negative terminal that is in conduction with the second terminal. The operational amplifier has a positive power supply terminal, a negative power supply terminal, a non-inverting input terminal, an inverting input terminal, and an output terminal. The operational amplifier has an output terminal and an inverting input terminal that are electrically connected to each other. The inspection device can connect the third terminal to the first terminal or the second terminal and a third terminal such that at least a portion of the first resistor or the bypass resistor is sandwiched between the third terminal and the first terminal or the second terminal. [Explanation of symbols]

[0077] DV1, DV2...Light emitting device LED1: Light emitting element R1…Resistor RD1, RD2, RD3...Detour resistor 100...Inspection equipment A1…constant current source VM1…Voltmeter OA1…Operational amplifier TL1: Terminal 1 TL2: Second terminal TL3…3rd terminal

Claims

1. A light emitting element having an anode terminal and a cathode terminal; a first resistor connected in series with the light emitting element; a bypass resistor connected in parallel with the light emitting element; A method for inspecting a light emitting device comprising: Using an operational amplifier with the inverting input terminal and the output terminal connected together, a first terminal electrically connected to a constant current source positive terminal of the constant current source and a voltmeter positive terminal of the voltmeter; a second terminal electrically connected to a constant current source negative terminal of the constant current source and a voltmeter negative terminal of the voltmeter; a third terminal that is electrically connected to the inverting input terminal or the non-inverting input terminal of the operational amplifier; The first terminal is connected to the anode terminal of the light emitting element; The second terminal is connected to the cathode terminal of the light emitting element; The third terminal is connected so as to sandwich at least a portion of a section of the first resistor or the bypass resistor between the first terminal or the second terminal and the third terminal; measuring a voltage between the anode terminal and the cathode terminal of the light-emitting element while passing a constant current through the light-emitting element; A method for inspecting a light emitting device comprising:

2. 2. The method for inspecting a light emitting device according to claim 1, connecting the third terminal so as to dispose the bypass resistor between the second terminal and the third terminal; A method for inspecting a light emitting device comprising:

3. 2. The method for inspecting a light emitting device according to claim 1, connecting the third terminal so as to dispose the first resistor between the first terminal and the third terminal; A method for inspecting a light emitting device comprising:

4. 2. The method for inspecting a light emitting device according to claim 1, The bypass resistor of the light emitting device is a first bypass resistor and a second bypass resistor connected in series with the first bypass resistor; connecting the third terminal such that the first bypass resistor is disposed between the first terminal and the third terminal; A method for inspecting a light emitting device comprising:

5. 2. The method for inspecting a light emitting device according to claim 1, The bypass resistor of the light emitting device is a first bypass resistor and a second bypass resistor connected in series with the first bypass resistor; connecting the third terminal such that the second bypass resistor is disposed between the second terminal and the third terminal; A method for inspecting a light emitting device comprising:

6. 1. A method for inspecting a light emitting device, comprising: The light emitting device comprises: A light-emitting element; a first resistor connected in series with the light emitting element; a bypass resistor connected in parallel with the light emitting element, While controlling a potential difference in at least a portion of the section of the first resistor or the bypass resistor to be −100 μV or more and 100 μV or less, measuring a voltage between an anode terminal and a cathode terminal of the light-emitting element while passing a constant current through the light-emitting element; A method for inspecting a light emitting device comprising:

7. 1. A method for inspecting a light emitting device, comprising: The light emitting device comprises: A light-emitting element; a first resistor connected in series with the light emitting element; a bypass resistor connected in parallel with the light emitting element, While controlling the potential difference in at least a part of the section of the first resistor or the bypass resistor to be zero, measuring a voltage between an anode terminal and a cathode terminal of the light-emitting element while passing a constant current through the light-emitting element; A method for inspecting a light emitting device comprising:

8. An inspection apparatus for a light emitting device including a light emitting element having an anode terminal and a cathode terminal, a first resistor connected in series with the light emitting element, and a bypass resistor connected in parallel with the light emitting element, a first terminal for connecting to the anode terminal of the light emitting element; a second terminal for connecting to the cathode terminal of the light emitting element; A third terminal; a constant current source that supplies a constant current between the first terminal and the second terminal; a voltmeter for measuring a voltage between the first terminal and the second terminal; An operational amplifier, having The constant current source is a positive terminal of a constant current source electrically connected to the first terminal; a constant current source negative terminal electrically connected to the second terminal, The voltmeter is a positive terminal of a voltmeter electrically connected to the first terminal; a voltmeter negative terminal in electrical communication with the second terminal, The operational amplifier is a positive power supply terminal, a negative power supply terminal, a non-inverting input terminal, an inverting input terminal, and an output terminal; The operational amplifier is the output terminal and the inverting input terminal are electrically connected to each other; The third terminal can be connected so that at least a portion of the first resistor or the bypass resistor is sandwiched between the first terminal or the second terminal and the third terminal. The inspection apparatus for a light emitting device comprising:

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