WO2013005652A1 - 発光素子故障検出器及び発光素子故障検出方法 - Google Patents
発光素子故障検出器及び発光素子故障検出方法 Download PDFInfo
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- WO2013005652A1 WO2013005652A1 PCT/JP2012/066610 JP2012066610W WO2013005652A1 WO 2013005652 A1 WO2013005652 A1 WO 2013005652A1 JP 2012066610 W JP2012066610 W JP 2012066610W WO 2013005652 A1 WO2013005652 A1 WO 2013005652A1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
- H05B45/3725—Switched mode power supply [SMPS]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/44—Testing lamps
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
- H10K71/861—Repairing
Definitions
- the present invention relates to a light emitting element failure detector and a light emitting element failure detecting method for detecting a failure of a light emitting element.
- an organic electroluminescence element hereinafter referred to as an organic EL element
- a voltage Vf corresponding to the impedance between the anode and cathode of the organic EL element is applied between the anode and cathode.
- This voltage Vf is lower than the voltage between the anode and cathode of the organic EL in a normal state.
- the failure detection means described in Patent Document 1 measures the potential Vf of the anode electrode of the organic EL element. When the potential Vf of the anode electrode is lower than the reference voltage, the failure detection means of Patent Document 1 detects a short circuit failure of the organic EL element.
- the impedance between the anode and the cathode of the organic EL element is lowered, so that the current flowing through the organic EL element is increased.
- the failure detection means described in Patent Document 2 measures the voltage of a resistor connected in series to the organic EL element. The increase in current can be detected from the measured voltage. Therefore, the failure detection means of Patent Document 2 detects a short-circuit failure when the measured voltage exceeds a predetermined threshold.
- the short circuit failure of the light emitting element can be detected by measuring the voltage Vf (output voltage) between the anode and the cathode of the light emitting element.
- the circuit protection unit (failure detection means) described in Patent Document 3 includes a first comparison unit and a second comparison unit.
- the first comparison unit outputs a high-level voltage when the output voltage of the LED (LIGHT EMITTING DIODE) is larger than the first reference voltage.
- the first comparison unit outputs a low level voltage when the output voltage of the LED is smaller than the first reference voltage.
- the second comparison unit compares the output voltage of the first comparison unit with the second reference voltage.
- the second comparison unit outputs a low level or high level voltage according to the result.
- the circuit protection unit detects a short-circuit failure from the output voltages of the first comparison unit and the second comparison unit.
- the failure detection means measures the voltage Vf between the anode and the cathode of the light emitting element or a voltage related to Vf. And the short circuit failure of a light emitting element is detected from the measured voltage and a reference voltage.
- the anode / cathode voltage Vf of the light emitting element varies depending on the VI characteristics of the element, changes with time, environmental temperature, and the like.
- the voltage Vf of the light emitting element also varies depending on the impedance between the anode and the cathode of the shorted light emitting element.
- the present invention has been made in view of the above circumstances, and provides a light-emitting element failure detector and a light-emitting element failure detection method capable of detecting a short-circuit failure without being affected by variations, changes, fluctuations, etc., of the voltage Vf of the light-emitting element.
- the purpose is to provide.
- a light-emitting element failure detector includes: A light-emitting element, a current supply path to the light-emitting element, a constant-current circuit that supplies current to the light-emitting element through the current supply path, and the constant-current circuit stops supplying current to the light-emitting element
- the light emitting element failure detector for detecting a short circuit of the light emitting element in the light emitting element circuit, comprising: a discharge path for discharging the charge accumulated in the light emitting element and a portion connected between the electrodes.
- a current interruption circuit that is arranged in the current supply path different from the discharge path, and that instantaneously interrupts the current that the constant current circuit supplies to the light emitting element;
- a voltage detector that obtains an output by measuring the voltage Vf between the anode and the cathode of the light emitting element during the instantaneous interruption;
- a determination unit for determining the presence or absence of a short circuit from the output; It is characterized by providing.
- the light emitting element failure detection method is: A light-emitting element, a current supply path to the light-emitting element, a constant-current circuit that supplies current to the light-emitting element through the current supply path, and the constant-current circuit stops supplying current to the light-emitting element
- the discharge path for discharging the charge accumulated in the site connected between the light emitting element and both electrodes thereof,
- a current instantaneous interruption step of instantaneously interrupting the current supplied to the light emitting element by the constant current circuit
- a determination step of determining the presence or absence of a short circuit from the output It is characterized by providing.
- the present invention it is possible to provide a light emitting element failure detector and a light emitting element failure detecting method capable of detecting a short circuit failure without being affected by variations, changes, fluctuations, etc. of the voltage Vf of the light emitting element.
- FIG. 1 It is a block diagram which shows the structure of a light emitting element circuit provided with the light emitting element failure detector which concerns on Embodiment 1 of this invention. It is a figure which shows operation
- FIG. 1 It is a block diagram which shows the structure of a light emitting element circuit provided with the light emitting element failure detector which concerns on Embodiment 1 of this invention. It is a figure which shows operation
- FIG. 3 is a flowchart illustrating a light emitting element failure detection process according to the first embodiment. It is a block diagram which shows the structure of the light emitting element circuit provided with the modification of the light emitting element failure detector of Embodiment 1. It is a block diagram which shows the structure of a light emitting element circuit provided with the light emitting element failure detector of Embodiment 2.
- FIG. 1 shows a configuration of a light emitting element circuit including a light emitting element failure detector according to Embodiment 1 of the present invention.
- the light emitting element circuit includes a light emitting element 1, a constant current circuit 2 that supplies a predetermined current to the light emitting element 1, an AC power source 3 that supplies power to the constant current circuit 2, and a light emitting element that detects a short circuit of the light emitting element 1.
- a failure detector 4 includes a current interruption circuit 5 and a failure detection unit 6.
- the capacitance is connected in parallel with the light emitting element 1.
- Capacitor 7 exhibits this capacitance (FIG. 1).
- a diode 8 is connected to the capacitor 7 and the light emitting element 1 in parallel.
- the coil 9 is connected to at least one of the electric paths connecting the capacitor 7 and the light emitting element 1 and the diode 8.
- the diode 8 is arranged with a polarity opposite to the polarity of the light emitting elements 1 connected in parallel.
- the capacitor 7, the light emitting element 1, the coil 9, and the diode 8 form a discharge path. This discharge path discharges the charge accumulated in the light emitting element 1 and the capacitor 7 when the current supply to the light emitting element 1 is stopped.
- the coil 9 may be a resistor.
- the resistor 10 is connected to the light emitting element 1 in series.
- the constant current circuit 2 supplies a current to the light emitting element 1 through the resistor 10.
- the instantaneous current interruption circuit 5 includes a switch unit 50 and a switch control unit 51.
- the switch unit 50 instantaneously cuts off the current by switching between supply and stop of the current.
- the switch control unit 51 controls instantaneous interruption of current by controlling switching of the switch unit 50.
- the switch unit 50 is configured by, for example, an FET (Field Effect Transistor).
- the switch unit 50 is disposed on a current supply path from the constant current circuit 2 to the light emitting element 1 and at a position different from the discharge path.
- the switch control unit 51 outputs an ON / OFF switching signal to the switch unit 50 at a predetermined timing.
- the switch control unit 51 outputs a switching signal to the gate electrode of the FET.
- the failure detection unit 6 includes a voltage detection unit 60, a DC power supply 61, and a determination unit 62.
- the voltage detection unit 60 has two input terminals and outputs a signal proportional to the voltage applied between the two terminals.
- the DC power supply 61 is connected to one of the two input terminals of the voltage detection unit 60, and outputs a reference voltage Vc that is a DC voltage to one of the input terminals.
- the determination unit 62 receives the output of the voltage detection unit 60 and determines the presence or absence of a short circuit failure based on the output.
- the voltage detector 60 is constituted by a differential amplifier, for example.
- the voltage detection unit 60 outputs the detection result when the voltage Vf between the anode and the cathode of the light emitting element 1 is detected and the voltage obtained by subtracting the reference voltage Vc, which is a fixed value, from the voltage Vf is input.
- a DC power supply 61 is connected in series to one of the two input terminals of the voltage detection unit 60.
- One input terminal is connected to the cathode of the light emitting element 1 via the DC power supply 61.
- the other of the two input terminals is connected to the anode of the light emitting element 1.
- the polarity of the reference voltage Vc is positive on the input terminal side and negative on the cathode side.
- a voltage of Vf ⁇ Vc is applied between the two input terminals of the voltage detector 60.
- the determination unit 62 receives an output from the voltage detection unit 60. Moreover, the determination part 62 determines the presence or absence of a short circuit failure from the output. If the determination unit 62 determines that a short circuit failure has occurred, the determination unit 62 outputs a control signal to the constant current circuit 2. The constant current circuit 2 inputs this control signal, thereby stopping the current supply to the light emitting element 1.
- FIG. 2A and 2B show the operation of the light emitting element failure detector 4 of the first embodiment.
- FIG. 2A shows a temporal change of the voltage Vf between the anode and the cathode of the light emitting element 1 in a normal state.
- FIG. 2B shows a change with time of the current flowing through the light emitting element 1 and the voltage Vf between the anode and the cathode of the light emitting element 1 when the current is momentarily interrupted with respect to the shorted light emitting element 1.
- the anode / cathode voltage Vf of the light emitting element 1 in a normal state is Vfn.
- the voltage Vf slightly decreases from Vfn to Vfn 0 as shown in FIG. 2A. That is, the voltage Vf does not rapidly decrease to 0V. This is because the time constant at which the charges accumulated in the capacitor 7 and the light emitting element 1 are discharged through the discharge path is large.
- the normal state refers to a state where no short circuit occurs.
- the light emitting element 1 when the light emitting element 1 is short-circuited, the light emitting element 1 can be replaced with a resistor having a small resistance value as an equivalent circuit. Accordingly, the voltage Vf of the light emitting element 1 is reduced to Vfa that is smaller than Vfn. Further, since the short-circuited light emitting element 1 has a small discharge time constant, the voltage Vf of the light emitting element 1 rapidly decreases to 0 V due to instantaneous interruption of current as shown in FIG. 2B.
- the momentary interruption period is set to a time when the light-emitting element 1 is short-circuited for a time longer than the time when the voltage Vf is reduced to 0 V and the light emission stop of the light-emitting element 1 due to the momentary interruption is not recognized by the observer.
- the period of this instantaneous interruption is obtained in advance by calculation or trial. Note that the voltage Vf of the light emitting element 1 in a normal state does not decrease to 0 V in a momentary interruption where the light emission stop of the light emitting element 1 is not recognized by the observer.
- the threshold for short circuit failure detection is set to be smaller than Vfn 0 and larger than 0V.
- the light emitting element failure detector 4 detects a short circuit. That is, the determination unit 62 determines that a short circuit failure has occurred.
- Threshold setting will be described in comparison with the conventional example (FIGS. 3A and 3B).
- the threshold value is set between Vfn and Vfa.
- the conventional light emitting element failure detector has detected the short circuit by whether Vf is below a threshold value.
- Vfn largely fluctuates due to variations in the VI characteristics of the light emitting element 1, temperature changes, aging changes, and the like.
- Vfa depends on the resistance component of the light-emitting element 1 that is short-circuited, Vfa greatly varies depending on the short-circuit state. Therefore, the threshold value is set within a range W that does not belong to either fluctuation range after predicting the fluctuations in Vfn and fa. Since this range W is narrow, it is difficult to set a threshold value.
- Vfn 0 varies due to variations in the VI characteristics of the light-emitting element 1, temperature changes, secular changes, etc., so the threshold value is smaller than the lower limit of the variation in Vfn 0 and more than 0V. It is set large (FIG. 3B). This range W 0 is very wide compared to the range W of the conventional example.
- the value larger than 0V indicates that it is practically larger than the value obtained by adding the tolerance ⁇ to 0V.
- the tolerance ⁇ may be a positive value.
- the tolerance ⁇ is set to 1 ⁇ 2 of the fluctuation width that the voltage Vf has in the vicinity of 0V.
- the light emitting element failure detector 4 can detect a case where the voltage Vf between the anode and the cathode of the light emitting element 1 is smaller than the threshold due to current interruption as a short circuit failure.
- the operation of the light emitting element failure detector 4 shown in FIG. 1 will be specifically described.
- the light emitting element 1 emits light by a current supplied from the constant current circuit 2 and is used for a lighting device, a display device, or the like.
- the instantaneous current interruption circuit 5 instantaneously interrupts the current supplied to the light emitting element 1 through a current supply path that is not a discharge path.
- the instantaneous interruption period is set as described above.
- the reference voltage Vc is set as a threshold value.
- the voltage detector 60 measures the voltage obtained by subtracting the reference voltage Vc from the voltage Vf between both electrodes of the light emitting element 1 as an input.
- the occurrence of a short circuit failure is determined by whether or not the voltage Vf is smaller than the reference voltage Vc when the current is momentarily interrupted.
- the determination unit 62 determines the occurrence of a short-circuit fault by the sign of the input voltage between the two input terminals of the voltage detection unit 60, that is, by the sign of the output of the voltage detection unit 60. To do.
- 0 is set as the determination criterion.
- the determination unit 62 determines the magnitude relationship between the output of the voltage detection unit 60 and the determination criterion.
- the input / output signs of the voltage detection unit 60 are designed to be the same (hereinafter, this is assumed, but when the input / output signs are reversed, it may be determined by reversing the sign) If the output of the detection unit 60 is negative, it is determined that a short circuit failure has occurred.
- the determination based on the determination criterion 0 in this case is equivalent to the determination whether the voltage Vf is smaller than the reference voltage Vc as a threshold value.
- the determination unit 62 determines that a short circuit failure has occurred, for example, the determination unit 62 outputs a control signal for stopping the current supply to the light emitting element 1 to the constant current circuit 2.
- FIG. 4 shows a flowchart of the light emitting element failure detection process.
- step S1 the constant current circuit 2 supplies a current to the light emitting element 1.
- the light emitting element 1 supplied with the current starts to emit light (step S1).
- the instantaneous current interruption circuit 5 instantaneously interrupts the current supply to the light emitting element 1 at a predetermined timing (step S2).
- the voltage detector 60 measures the anode / cathode voltage Vf of the light emitting element 1 (step S3).
- the voltage detector 60 receives a voltage obtained by subtracting the reference voltage Vc from the voltage Vf as an input, and obtains the measurement result as an output.
- the determination part 62 determines whether the output of the voltage detection part 60 is smaller than the determination reference
- step S4 If the output of the voltage detection unit 60 is smaller than the criterion 0, that is, if the sign of the output is negative (step S4; YES), it is determined that a short circuit fault has occurred. By this determination, for example, a measure for coping with a short circuit such as turning off the constant current circuit 2 and stopping the current supply to the light emitting element 1 is performed (step S5). Thereby, the light emitting element failure detection process is completed. If the output of the voltage detection unit 60 is greater than or equal to the determination criterion 0, that is, if the sign of the output is positive or 0 (step S4; NO), the determination unit 62 determines that the light emitting element 1 is normal.
- the process returns to step S2, and each component repeats the light emitting element failure detection process.
- the measure for dealing with the short circuit is, for example, in addition to stopping the current supply to the light emitting element 1 by turning off the constant current circuit 2 or stopping the current supply and displaying the occurrence of a short circuit failure. Or sound an alarm.
- the range W 0 in which the threshold (reference voltage Vc) shown in FIG. 3B can be set is wider than the conventional range W in which the threshold shown in FIG. 3A can be set.
- the lower limit of the range W 0 does not need to consider fluctuations, and may be larger than 0V. Therefore, by setting the threshold value to the vicinity of 0V with the tolerance ⁇ or more, the fluctuation range of Vfn 0 is practically not taken into consideration, in other words, variations in VI characteristics, temporal changes, environmental temperatures, etc. It can be said that the threshold value (here, the reference voltage Vc) serving as a reference for short-circuit fault detection can be set without considering variations and without considering the degree of short-circuit fault.
- the DC power supply 61 may be connected to the other input terminal instead of the input terminal shown in FIG. However, in this case, the DC power supply 61 applies a voltage having a polarity opposite to that in the case of FIG. 1 so that the potential on the anode side of the voltage detection unit 60 is lowered by the reference voltage Vc. In this way, the output of the voltage detection unit 60 is the same as that of the configuration shown in FIG.
- the determination unit 62 may be included in the voltage detection unit 60.
- the voltage detection unit 60 outputs a predetermined output only when the input voltage between the two input terminals becomes a negative value.
- the determination unit 62 is not necessarily included in the failure detection unit 6.
- the constant current circuit 2 may be designed to be turned off.
- the determination unit 62 is substantially built in the constant current circuit 2.
- step S4 in the flowchart shown in FIG. 4 is substantially executed in the constant current circuit 2.
- switch part 50 by FET
- IGBT Insulated Gate Bipolar Transistor
- FIG. 5 shows a modification of the light emitting element failure detector 4 according to the first embodiment.
- the DC power supply 61 is not used, and the two input terminals of the voltage detection unit 60 are directly connected to the anode and the cathode of the light emitting element 1, respectively.
- the determination unit 62 does not determine the sign of the output of the voltage detection unit 60 but determines whether the output of the voltage detection unit 60 is smaller than a determination criterion ⁇ different from zero.
- the determination unit 62 determines that the output of the voltage detection unit 60 is smaller than the determination reference ⁇ , the determination unit 62 determines that a short-circuit failure has occurred and executes a predetermined process when the short-circuit failure occurs. If the determination unit 62 determines that the output of the voltage detection unit 60 is greater than or equal to the determination criterion ⁇ , the determination unit 62 determines that a short circuit failure has not occurred and is normal.
- the determination criterion ⁇ is a value corresponding to an output when the reference voltage Vc is input between the two input terminals of the voltage detection unit 60 in comparison with the first embodiment.
- this determination by the determination unit 62 is equivalent to determining whether or not the voltage Vf is smaller than the reference voltage Vc that is a threshold value. Also in this modification, the voltage detection unit 60 or the constant current circuit 2 may be configured to include the determination unit 62.
- a current interruption circuit 5 may be installed in the light emitting element circuit.
- the failure detection unit 6 can be installed between the anode / cathode of each light emitting element 1. Thereby, when a short circuit failure occurs in any one of the light emitting elements 1, this can be detected. Further, based on the detection result, for example, the constant current circuit 2 can be turned off, and the supply of current to the plurality of light emitting elements 1 as a whole can be stopped. By taking such a measure, an excessive voltage is not applied to the other normal light-emitting elements 1, so that it is possible to prevent a failure from being induced.
- the measure when a short circuit failure is detected is not limited to this, and various measures can be taken in accordance with predetermined contents.
- the threshold (or reference voltage Vc) serving as a reference for short circuit failure detection is the voltage between the anode and the cathode of the light emitting element 1. It is set without being affected by variations, changes, fluctuations, etc. of Vf. Therefore, according to the present embodiment, a light emitting element failure detector 4 and a light emitting element failure detecting method capable of detecting a short circuit failure without being affected by variations, changes, fluctuations, etc. of the anode / cathode voltage Vf of the light emitting element 1 are provided. can do.
- FIG. 6 shows a configuration example of a light emitting element circuit including the light emitting element failure detector 4 according to the second embodiment.
- the light emitting element circuit uses PWM (Pulse Width Modulation) control for dimming control of the light emitting element 1.
- PWM Pulse Width Modulation
- a pulse train having a predetermined frequency is supplied to the light emitting element 1. Dimming of the light emitting element 1 is controlled by the pulse width of the supplied pulse.
- the light emitting element circuit of the present embodiment includes a PWM dimming circuit 11.
- the PWM dimming circuit 11 includes a current control switch 110, a dimming level setting unit 111, a PWM signal generation unit 112, and a drive circuit 113.
- the current control switch 110 is installed in a current supply path to the light emitting element 1 different from the discharge path. In addition, the current control switch 110 performs ON / OFF control of current supply to the light emitting element 1.
- the current control switch 110 is composed of, for example, an FET (FIG. 5).
- the dimming level setting unit 111 sets the dimming level of the light emitting element 1.
- the PWM signal generation unit 112 selects a pulse width from the set dimming level.
- the PWM signal generation unit 112 generates a pulse train (PWM signal) with a predetermined frequency having a selected pulse width.
- the drive circuit 113 controls ON / OFF of current supply by the current control switch 110 according to the PWM signal.
- Other configurations are the same as those of the first embodiment.
- the instantaneous current interruption circuit 5 in the first embodiment is configured by a part of the PWM dimming circuit 11.
- the current control switch 111 also serves as the switch unit 50 in the first embodiment.
- the PWM signal generation unit 112 and the drive circuit 113 also serve as the switch control unit 51 in the first embodiment.
- Embodiment 2 is characterized in that the PWM signal generation unit 112 generates a pulse train by continuously decimating a part of the pulse train at a predetermined cycle. For example, one pulse or a plurality of pulses per N pulses are continuously thinned out from the pulse train. A period in which no pulse is generated due to the thinning corresponds to a current interruption period in the first embodiment.
- Embodiment 2 since current is supplied to the light-emitting element 1 in a pulse train, instantaneous interruption of the current constantly occurs. Therefore, the voltage is constantly reduced according to the pulse train. However, when the pulse train is continuous, the instantaneous interruption period is very short, so that the voltage Vf does not drop rapidly to 0V.
- the PWM signal generation unit 112 selects the number of pulses to be continuously thinned out from the time when the voltage Vf is reduced to 0 V and the pulse width in a state where the light emitting element 1 is short-circuited.
- the setting of the instantaneous interruption period is the same as that in the first embodiment.
- the pulse width is selected by the PWM signal generator 112 according to the dimming level.
- Embodiment 1 The operation of this embodiment is the same as that of Embodiment 1 except for the method of instantaneous interruption.
- the processing content of “execution of instantaneous interruption of current supply at a predetermined timing” is executed in the second embodiment.
- “instantaneous interruption of current supply is performed by thinning out pulses from a pulse train at a predetermined timing”. If the content is changed to “execute”, the flowchart of FIG.
- the PWM signal generation unit 112 generates a pulse train obtained by thinning out pulses at a predetermined period.
- the PWM signal generation unit 112 and the drive circuit 113 have the function of the switch control unit 51 in the first embodiment.
- the current control switch 110 also has the function of the switch unit 50 in the first embodiment.
- the instantaneous current interruption circuit 5 can be realized without adding new hardware.
- the light emitting element failure detector 4 in the present embodiment has the same effects as those described in the first embodiment.
- the configuration of the failure detection unit 6 shown in FIG. 6 may be replaced with the configuration of the failure detection unit 6 shown in FIG.
- the illustrated circuit configuration is an example, and can be arbitrarily changed as long as the same function can be obtained.
- the light emitting element failure detector 4 can be composed of a CPU (Central Processing Unit), a memory, and the like.
- the CPU can execute the above-described light emitting element failure detection process by executing a program stored in the memory.
- the light emitting element 1 may be an LED (LIGHT EMITTING DIODE) element in addition to the organic EL element.
- the current was momentarily interrupted by using the switch control unit 51 that outputs the ON / OFF switching signal at a predetermined timing or the PWM dimming function of the PWM dimming circuit 11, but the light emitting element 1 has another configuration.
- the current flowing in the battery may be momentarily interrupted.
- a bypass means may be provided in the current supply path of the light emitting element circuit so as to prevent current from flowing to the light emitting element 1.
- the voltage detection unit 60 including a differential amplifier connected in parallel to the light-emitting element 1 is used, other detection methods are used. May be.
- the determination unit 62 outputs a control signal for stopping the current supply to the light emitting element 1 to the constant current circuit 2, but outputs the control signal to the switch unit 50 of the instantaneous current interruption circuit 5 to output the switch unit 50. May be switched off to stop the current supply to the light emitting element 1.
- the determination unit 62 may be configured to continuously output the control signal by providing, for example, a flip-flop at the output stage of the determination unit 62.
- the light emitting element failure detector for detecting a short circuit of the light emitting element in the light emitting element circuit, comprising: a discharge path for discharging the charge accumulated in the light emitting element and a portion connected between the electrodes.
- a current interruption circuit that is arranged in the current supply path different from the discharge path, and that instantaneously interrupts the current that the constant current circuit supplies to the light emitting element;
- a voltage detector that obtains an output by measuring the voltage Vf between the anode and the cathode of the light emitting element during the instantaneous interruption;
- a determination unit for determining the presence or absence of a short circuit from the output;
- a light emitting element failure detector A current interruption circuit that is arranged in the current supply path different from the discharge path, and that instantaneously interrupts the current that the constant current circuit supplies to the light emitting element.
- a predetermined DC voltage is generated, and includes a DC power source connected to one of the input terminals of the voltage detection unit,
- the DC voltage has a polarity such that a potential difference between the input terminals is equal to a voltage obtained by subtracting an absolute value of the DC voltage from the voltage Vf.
- the output is an output when the potential difference between the input terminals is equal to a voltage obtained by subtracting the absolute value of the DC voltage from the voltage Vf.
- the determination unit determines the presence or absence of a short circuit based on the sign of the output.
- the current interruption circuit is A switch section for switching between supply and stop of current from the constant current circuit to the light emitting element; A switch control unit that controls the switching of the switch unit, The light-emitting element failure detector according to Supplementary Note 1 or 2, wherein:
- the light emitting element circuit sets a pulse width based on the set dimming level, generates a PWM signal composed of a pulse train of the set pulse width, and the PWM signal generation unit generates the PWM signal.
- a drive circuit that receives a PWM signal and outputs a PWM control signal composed of a pulse train of the same pattern as the PWM signal, and is installed in the current supply path, receives the PWM control signal, and the light emitting element is input by the PWM control signal
- a current control switch that switches between supply and stop of current to The PWM signal generation unit generates the PWM signal by continuously removing at least one pulse or more from the pulse train at a predetermined cycle, and supplies the generated PWM signal to the drive circuit,
- the current control switch installed in the current supply path different from the discharge path also serves as the switch section, By setting the period in which no pulse exists as a period in which the current is momentarily interrupted, the PWM signal generation unit and the drive circuit also serve as the switch control unit.
- the PWM signal generation unit selects the number of pulses to be continuously removed from the set pulse width and the preset interruption period.
- the light-emitting element failure detector according to appendix 4, wherein:
- the light emitting element is an organic EL element.
- the light emitting element failure detector according to any one of appendices 1 to 5, characterized in that:
- the light emitting element is an LED element.
- the light emitting element failure detector according to any one of appendices 1 to 5, characterized in that:
- the discharge path for discharging the charge accumulated in the site connected between the light emitting element and both electrodes thereof,
- a current instantaneous interruption step of instantaneously interrupting the current supplied to the light emitting element by the constant current circuit
- a light emitting element failure detection method comprising:
- the present invention is suitable for a light emitting element failure detector and a light emitting element failure detecting method for detecting a failure of a light emitting element.
Abstract
Description
発光素子と、該発光素子への電流供給路と、該電流供給路を介して前記発光素子に電流を供給する定電流回路と、前記定電流回路が前記発光素子への電流供給を停止した場合に前記発光素子及びその両電極間に接続する部位に蓄積する電荷を放電する放電路と、を備える発光素子回路中の前記発光素子の短絡を検出する発光素子故障検出器において、
前記放電路とは異なる前記電流供給路に配置され、前記定電流回路が前記発光素子に供給する電流を瞬断する電流瞬断回路と、
前記発光素子のアノードとカソードとの間の前記瞬断の期間の電圧Vfを測定対象として出力を得る電圧検出部と、
前記出力から短絡の有無を判定する判定部と、
を備えることを特徴とする。
発光素子と、該発光素子への電流供給路と、該電流供給路を介して前記発光素子に電流を供給する定電流回路と、前記定電流回路が前記発光素子への電流供給を停止した場合に前記発光素子及びその両電極間に接続する部位に蓄積する電荷を放電する放電路と、を備える発光素子回路中の前記発光素子の短絡を検出する発光素子故障検出方法において、
前記放電路とは異なる前記電流供給路で、前記定電流回路が前記発光素子に供給する電流を瞬断する電流瞬断ステップと、
前記発光素子のアノードとカソードとの間の前記瞬断の期間の電圧Vfを測定対象として出力を得る電圧検出ステップと、
前記出力から短絡の有無を判定する判定ステップと、
を備えることを特徴とする。
図1は、本発明の実施形態1に係る発光素子故障検出器を含む発光素子回路の構成を示す。発光素子回路は、発光素子1と、発光素子1に所定の電流を供給する定電流回路2と、定電流回路2に電力を供給する交流電源3と、発光素子1の短絡を検出する発光素子故障検出器4とを備える。また、発光素子故障検出器4は、電流瞬断回路5と、故障検出部6とを備える。
図6は、実施形態2に係る発光素子故障検出器4を備える発光素子回路の構成例を示す。本実施形態においては、発光素子回路は、発光素子1の調光制御にPWM(Pulse Width Modulation)制御を使用する。
発光素子と、該発光素子への電流供給路と、該電流供給路を介して前記発光素子に電流を供給する定電流回路と、前記定電流回路が前記発光素子への電流供給を停止した場合に前記発光素子及びその両電極間に接続する部位に蓄積する電荷を放電する放電路と、を備える発光素子回路中の前記発光素子の短絡を検出する発光素子故障検出器において、
前記放電路とは異なる前記電流供給路に配置され、前記定電流回路が前記発光素子に供給する電流を瞬断する電流瞬断回路と、
前記発光素子のアノードとカソードとの間の前記瞬断の期間の電圧Vfを測定対象として出力を得る電圧検出部と、
前記出力から短絡の有無を判定する判定部と、
を備えることを特徴とする発光素子故障検出器。
所定の直流電圧を発生し、前記電圧検出部の入力端子の一方に接続される直流電源を備え、
前記直流電圧は、前記入力端子間の電位差が、前記電圧Vfから前記直流電圧の絶対値が差し引かれた電圧に等しくなる極性を有し、
前記出力は、前記入力端子間の電位差が、前記電圧Vfから前記直流電圧の絶対値が差し引かれた電圧に等しい場合の出力であり、
前記判定部は、前記出力の符号により短絡の有無を判定する、
ことを特徴とする付記1に記載の発光素子故障検出器。
前記電流瞬断回路は、
前記定電流回路から前記発光素子への電流の供給と停止の切り換えるスイッチ部と、
該スイッチ部の前記切り換えを制御するスイッチ制御部と、を備える、
ことを特徴とする付記1又は2に記載の発光素子故障検出器。
前記発光素子回路は、設定された調光レベルに基づきパルス幅を設定し、該設定したパルス幅のパルス列からなるPWM信号を生成するPWM信号生成部と、該PWM信号生成部で生成された前記PWM信号を受け、該PWM信号と同じパターンのパルス列からなるPWM制御信号を出力する駆動回路と、前記電流供給路に設置され、前記PWM制御信号を入力し、該PWM制御信号により、前記発光素子への電流の供給と停止を切り換える電流制御スイッチと、を更に備え、
前記PWM信号生成部は、前記パルス列から所定の周期で少なくとも1パルス以上のパルスを連続して除いて前記PWM信号を生成し、該生成されたPWM信号を前記駆動回路に供給し、
前記放電路と異なる前記電流供給路に設置された前記電流制御スイッチは、前記スイッチ部を兼用し、
パルスの存在しない期間を前記電流を瞬断した期間とすることにより、前記PWM信号生成部と前記駆動回路が前記スイッ制御部を兼用する、
ことを特徴とする付記3に記載の発光素子故障検出器。
前記PWM信号生成部は、前記設定されたパルス幅と、あらかじめ設定された前記瞬断の期間とから前記連続して除くパルスの数を選択する、
ことを特徴とする付記4に記載の発光素子故障検出器。
前記発光素子は、有機EL素子である、
ことを特徴とする付記1乃至5のいずれか1つに記載の発光素子故障検出器。
前記発光素子は、LED素子である、
ことを特徴とする付記1乃至5のいずれか1つに記載の発光素子故障検出器。
発光素子と、該発光素子への電流供給路と、該電流供給路を介して前記発光素子に電流を供給する定電流回路と、前記定電流回路が前記発光素子への電流供給を停止した場合に前記発光素子及びその両電極間に接続する部位に蓄積する電荷を放電する放電路と、を備える発光素子回路中の前記発光素子の短絡を検出する発光素子故障検出方法において、
前記放電路とは異なる前記電流供給路で、前記定電流回路が前記発光素子に供給する電流を瞬断する電流瞬断ステップと、
前記発光素子のアノードとカソードとの間の前記瞬断の期間の電圧Vfを測定対象として出力を得る電圧検出ステップと、
前記出力から短絡の有無を判定する判定ステップと、
を備えることを特徴とする発光素子故障検出方法。
2 定電流回路
3 交流電源
4 発光素子故障検出器
5 電流瞬断回路
6 故障検出部
7 コンデンサ
8 ダイオード
9 コイル
10 抵抗
11 PWM調光回路
50 スイッチ部
51 スイッチ制御部
60 電圧検出部
61 直流電源
62 判定部
110 電流制御スイッチ
111 調光レベル設定部
112 PWM信号生成部
113 駆動回路
Claims (8)
- 発光素子と、該発光素子への電流供給路と、該電流供給路を介して前記発光素子に電流を供給する定電流回路と、前記定電流回路が前記発光素子への電流供給を停止した場合に前記発光素子及びその両電極間に接続する部位に蓄積する電荷を放電する放電路と、を備える発光素子回路中の前記発光素子の短絡を検出する発光素子故障検出器において、
前記放電路とは異なる前記電流供給路に配置され、前記定電流回路が前記発光素子に供給する電流を瞬断する電流瞬断回路と、
前記発光素子のアノードとカソードとの間の前記瞬断の期間の電圧Vfを測定対象として出力を得る電圧検出部と、
前記出力から短絡の有無を判定する判定部と、
を備えることを特徴とする発光素子故障検出器。 - 所定の直流電圧を発生し、前記電圧検出部の入力端子の一方に接続される直流電源を備え、
前記直流電圧は、前記入力端子間の電位差が、前記電圧Vfから前記直流電圧の絶対値が差し引かれた電圧に等しくなる極性を有し、
前記出力は、前記入力端子間の電位差が、前記電圧Vfから前記直流電圧の絶対値が差し引かれた電圧に等しい場合の出力であり、
前記判定部は、前記出力の符号により短絡の有無を判定する、
ことを特徴とする請求項1に記載の発光素子故障検出器。 - 前記電流瞬断回路は、
前記定電流回路から前記発光素子への電流の供給と停止の切り換えるスイッチ部と、
該スイッチ部の前記切り換えを制御するスイッチ制御部と、を備える、
ことを特徴とする請求項1又は2に記載の発光素子故障検出器。 - 前記発光素子回路は、設定された調光レベルに基づきパルス幅を設定し、該設定したパルス幅のパルス列からなるPWM信号を生成するPWM信号生成部と、該PWM信号生成部で生成された前記PWM信号を受け、該PWM信号と同じパターンのパルス列からなるPWM制御信号を出力する駆動回路と、前記電流供給路に設置され、前記PWM制御信号を入力し、該PWM制御信号により、前記発光素子への電流の供給と停止を切り換える電流制御スイッチと、を更に備え、
前記PWM信号生成部は、前記パルス列から所定の周期で少なくとも1パルス以上のパルスを連続して除いて前記PWM信号を生成し、該生成されたPWM信号を前記駆動回路に供給し、
前記放電路と異なる前記電流供給路に設置された前記電流制御スイッチは、前記スイッチ部を兼用し、
パルスの存在しない期間を前記電流を瞬断した期間とすることにより、前記PWM信号生成部と前記駆動回路が前記スイッ制御部を兼用する、
ことを特徴とする請求項3に記載の発光素子故障検出器。 - 前記PWM信号生成部は、前記設定されたパルス幅と、あらかじめ設定された前記瞬断の期間とから前記連続して除くパルスの数を選択する、
ことを特徴とする請求項4に記載の発光素子故障検出器。 - 前記発光素子は、有機EL素子である、
ことを特徴とする請求項1乃至5のいずれか1項に記載の発光素子故障検出器。 - 前記発光素子は、LED素子である、
ことを特徴とする請求項1乃至5のいずれか1項に記載の発光素子故障検出器。 - 発光素子と、該発光素子への電流供給路と、該電流供給路を介して前記発光素子に電流を供給する定電流回路と、前記定電流回路が前記発光素子への電流供給を停止した場合に前記発光素子及びその両電極間に接続する部位に蓄積する電荷を放電する放電路と、を備える発光素子回路中の前記発光素子の短絡を検出する発光素子故障検出方法において、
前記放電路とは異なる前記電流供給路で、前記定電流回路が前記発光素子に供給する電流を瞬断する電流瞬断ステップと、
前記発光素子のアノードとカソードとの間の前記瞬断の期間の電圧Vfを測定対象として出力を得る電圧検出ステップと、
前記出力から短絡の有無を判定する判定ステップと、
を備えることを特徴とする発光素子故障検出方法。
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