JP2013109964A - Light-emitting element lighting device and illuminating device having its circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element lighting device having protection means that detects abnormalities caused by serious damages of a light-emitting element to protect the light-emitting element and peripheral circuits.SOLUTION: A light-emitting element lighting device (9a) using an organic EL light-emitting element has: current controllers (12, 13a) controlling a current flowing in the light-emitting element to a constant current; and a detector (13b) detecting a both-end voltage of the light-emitting element. The current controllers calculate a voltage change amount per unit time, of the detected voltage, and in the case that the calculated change amount exceeds a threshold of a value larger than a value detected at an operation in a rated range, reduce a current amount to be supplied by the power supply part to the light-emitting element or stop the current. By employing the configuration, in the case that the organic EL light-emitting element is damaged seriously and deformed in usage, the current to be supplied to the light-emitting element is reduced or stopped to protect the light-emitting element and peripheral circuits.

Description

  The present invention relates to a light-emitting element lighting device that lights a light-emitting element such as an organic EL, and an illumination device having the circuit.

  In the light-emitting element lighting device, it is determined that the circuit is short-circuited or opened when abnormal power supply is performed to the light-emitting element due to the occurrence of abnormality such as destruction or failure of the light-emitting element or the power supply circuit of the light-emitting element. However, some have a circuit for reducing or stopping power supply to the light emitting element.

  For example, in Patent Document 1, a voltage that is applied to a light-emitting element is detected, and when this voltage exceeds an upper limit value or falls below a lower limit value, a current that flows in the circuit is determined to be abnormal. A light emitting element lighting device having means for reducing or stopping the quantity is described.

JP 2011-146329 A

  However, the lighting device described in Patent Document 1 performs abnormality detection when the light emitting element is partially destroyed by an external impact or the like while the light emitting element lighting device performs constant current control on the light emitting element. May not be possible. The term “half broken” refers to a state in which the light emitting element is deformed and broken due to external force, for example, but is not completely broken and the circuit is not short-circuited or opened. That is, although the resistance value has rapidly decreased, no abnormality is detected in the lighting device described in Patent Document 1 unless the voltage applied to the light emitting element thereafter falls below the lower limit value. In this case, since abnormal lighting such as partial lighting of the light emitting element is continued, the light emitting element and the peripheral circuit may be damaged due to a partial temperature rise. In particular, since the organic EL light emitting element is a thin surface emitting light source, it is likely to be in a semi-destructed state described above.

  The present invention has been made to solve the above-described problems of conventional light-emitting element lighting devices, and detects or detects the abnormality caused by the partial destruction of the light-emitting element, thereby reducing or stopping the amount of current flowing through the light-emitting element. An object of the present invention is to provide a light emitting element lighting device having a protective function.

  In order to achieve the above object, the present invention provides a light-emitting element lighting device for lighting an organic EL light-emitting element, a current control unit for controlling a current flowing through the light-emitting element to a constant value, and a voltage for detecting a voltage across the light-emitting element. A detection unit, wherein the current control unit calculates a voltage change amount per unit time of the voltage detected by the voltage detection unit, and the calculated change amount is a value detected during operation within a rated range. When the threshold value of a larger value is exceeded, the amount of current flowing through the light emitting element is reduced or stopped.

  In the light-emitting element lighting device, it is preferable that the threshold value is set to a value larger than a voltage change amount caused by a temperature change in a setting environment.

  In the light emitting element lighting device, the current control unit further stops the current flowing through the light emitting element when the voltage detected by the voltage detection unit falls below a lower limit value or exceeds an upper limit value. Is preferred.

  In the light emitting element lighting device, the current control unit generates a PWM dimming signal having a duty ratio determined according to an input dimming signal, and causes a PWM current to flow through the light emitting element based on the signal. It is preferable.

  The lighting device of the present invention includes one or more organic EL light emitting elements, any one of the above light emitting element lighting devices for lighting each light emitting element, and a power supply unit that supplies power to the light emitting element lighting device. The light emitting panel is provided.

  In the illumination device, it is preferable that the current control unit generates a PWM dimming signal having a duty ratio determined according to a dimming signal input from the outside, and performs current control based on the signal.

  According to the present invention, when the voltage applied to the organic EL light emitting element changes more rapidly than during the rated operation, the current control unit determines that the light emitting element has failed. Therefore, even when the voltage after the change applied to the light emitting element is not a value representing a short circuit or an open circuit between the input and output terminals of the light emitting element, the circuit element of the light emitting element and its peripheral circuit can be protected.

The perspective view of the illuminating device which has the light emitting element lighting device which concerns on an Example. The block diagram of an illuminating device. The circuit diagram of a light emitting element lighting device. The time chart of the input / output waveform of the comparator. The process flowchart which a control part performs. An example which shows the change with progress of time of the voltage applied to a light emitting element.

  The light emitting element lighting device of the lighting device according to the embodiment includes a current control unit that controls a current flowing through the light emitting element to be constant, and a detection unit that detects a voltage across the light emitting element. The current control unit reduces or stops the amount of current flowing through the light emitting element when the change amount of the voltage exceeds a threshold value. In addition, the said light emitting element uses the thing which internal resistance changes by deform | transforming at the time of abnormality generation | occurrence | production such as half destruction by external factors like an organic EL light emitting element. For example, the current control unit supplies a constant current of a DC type or a constant current of a PWM type based on a PWM dimming signal to the light emitting element. The amount of change is obtained by periodically detecting a voltage applied to the light emitting element (for example, every 10 ms) and changing the detected voltage per unit time (for example, 100 ms) (| positive or negative change value | / t ) Is calculated. The threshold value is a value larger than a value detected during operation within the rated range (or during stable operation of the circuit). Examples of the lighting device having the above configuration will be described below.

  FIG. 1 is a perspective view of a lighting device 1 having a light emitting element lighting device having the above-described configuration. The lighting device 1 includes a light emitting unit 2, a hanging tool 3 for hanging the light emitting unit 2 on the ceiling, and a power cord 4 that connects the light emitting unit 2 and the hanging tool 3. The hanger 3 connects a commercial AC voltage power supply line provided on the ceiling and the power cord 4. Thereby, the commercial AC voltage is supplied to the light emitting unit 2 through the power cord 4. The light emitting unit 2 includes a light emitting panel 2a having an organic EL light emitting element, and a frame 2b surrounding the light emitting panel 2a.

FIG. 2 shows a configuration of the light emitting panel 2a. The light emitting panel 2a includes a power supply unit 5 that receives a commercial AC voltage, converts the input AC voltage into a DC voltage, and outputs the DC voltage, and two light emitting units 6 and 7 having the same configuration. Only the light emitting unit 6 will be described below. The light emitting unit 6 includes three light emitting element modules 6a to 6c having the same configuration. Hereinafter, only the light emitting element module 6a will be described. The light emitting element module 6a includes an organic EL light emitting element 8a, a light emitting element lighting device 9a for the light emitting element 8a, and a receiving unit 10a that receives a dimming signal transmitted from a remote controller (not shown). The light emitting element 8a is, for example, an organic EL light emitting element having a rated voltage of 7.5 V, a rated current of 0.3 A, and a light emitting area of 64 cm ² . When an organic EL light emitting element is deformed by being applied with force from the outside and is partially broken, the internal resistance is greatly reduced. The receiving unit 10a outputs the received dimming signal to the light emitting element lighting device 9a. The light emitting element lighting device 9a receives power supply from the power supply unit 5, generates a PWM dimming signal having a duty ratio determined according to the dimming signal from the receiving unit 10a, and generates the generated PWM dimming signal (PWM type) Is supplied to the light emitting element 8a. The light emitting element lighting device 9a performs PWM constant current control so that the maximum amplitude value of the PWM dimming signal is stabilized.

  FIG. 3 is a circuit diagram of the light emitting element lighting device 9a connected to the light emitting element 8a. The light-emitting element lighting device 9a includes an internal circuit drive voltage Vcc generation circuit 11, a signal generation circuit 12 for the light-emitting element 8a and a control section 13 as a current control unit that controls the current flowing through the light-emitting element 8a constant, It has.

  The drive power supply Vcc generation circuit 11 divides the DC voltage supplied from the power supply unit 5 by the resistors R1 and R2 connected in series to generate the drive voltage Vcc for driving the signal generation circuit 12 and the control IC 13. Generate.

  The signal generation circuit 12 includes a PWM dimming signal generation circuit 12a that generates and outputs a PWM signal having a duty ratio corresponding to the dimming signal, a step-down chopper circuit 12b that operates based on the PWM dimming signal, and a light emitting element And a current detector 12c that detects a current flowing through 8a. The step-down chopper circuit 12b includes a smoothing capacitor C1, a switching transistor Q1, a diode D1, a reactance L1, and a capacitor C2, and is a general step-down chopper circuit having a configuration shown in the drawing. The step-down chopper circuit 12b includes a drive signal generation circuit 12d that chops the drive transistor 12c during the ON period of the PWM dimming signal from the PWM dimming signal generation circuit 12a.

  The PWM dimming signal generation circuit 12a includes two comparators OP1 and OP2. The comparator OP2 outputs a PWM dimming signal corresponding to the dimming signal. The output of the comparator OP1 is input to the non-inverting input terminal (+) of the comparator OP2. The comparator OP1 outputs a reference voltage Vref0 that determines the duty ratio of the PWM dimming signal. The inverting input terminal (−) of the comparator OP2 has a voltage that becomes 0V when the switching transistor Q8 is turned on and is increased when the power supply Vcc inputted through the resistor R14 is accumulated in the capacitor C4 when turned off. Applied. The switching transistor Q8 is turned on / off based on a signal output from the second pin of the control IC 13a described later. The comparator OP2 outputs a high level signal during a period in which the voltage input to the inverting input terminal (−) is lower than the voltage input to the non-inverting input terminal (+) from OP1.

  In FIG. 4, (a) is the second pin, (b) is the inverting input terminal (−) of the comparator OP2, (c) is the non-inverting input terminal (+) of the comparator OP2, and (d) is the comparator OP2. Represents the signal at the output terminal. As shown in the figure, the duty ratio of the PWM dimming signal changes according to the reference voltage Vref0 output from the comparator OP1.

  Refer to FIG. 3 again. The signal generation circuit 12 further functions as a power supply unit that supplies a constant current for lighting to the light emitting element 8a. A current detection voltage proportional to the current flowing through the light emitting element 8a detected by the current detection resistor R3 of the current detection unit 12c is input to the inverting input terminal (−) of the comparator OP1. The switching transistor Q6 is connected to the midpoint of the voltage dividing circuit composed of R8 and R9 connected in series. Two types of reference voltages Vref1 / Vref2 are input to the non-inverting input terminal (+) of the comparator OP1 according to the on / off state of the switching transistor Q6. When no abnormality has occurred, the switching transistor Q6 is turned off, and Vref2 (> Vref1) is input to the non-inverting input terminal (+) of the comparator OP1. The comparator OP1 outputs the comparison result to the non-inverting input terminal (+) of the comparator OP2. With the above configuration, the reference voltage Vref0 output from the comparator OP1 is increased / decreased according to the amount of current flowing through the current detector 12c. As a result, the duty ratio of the signal output from the comparator OP2 is increased / decreased to perform constant current control. Is called.

  The PWM dimming signal generation circuit 12a further includes a switching transistor Q7 that is turned on to bring the potential of the non-inverting input terminal (+) of the comparator OP1 to 0V. When detecting an abnormality described later, the switching transistor Q7 is turned on to stop the signal output from the comparator OP2. In addition, the value of Vref1 is set to a value close to 0V such as 0.1 to 1V, and a configuration is adopted in which the switching transistor Q6 is turned on when an abnormality is detected, thereby greatly reducing the signal output from the comparator OP2. You may reduce the electric current which flows into the light emitting element 8a. As will be described later, a configuration in which the switching transistor Q6 is first turned on and then the switching transistor Q7 is turned on in accordance with the degree of abnormality, that is, the amount of change in voltage applied to the light emitting element may be adopted. Good.

  The control unit 13 includes a control IC 13a and a voltage dividing circuit 13b including a resistor R4 and a resistor R5 connected in series. The control IC 13a is a computer having an A / D conversion unit 13c, a storage unit 13d, and a calculation unit 13e that executes a program stored in the storage unit 13d. The power supply voltage Vcc generated by the drive power supply Vcc generation circuit 11 is input to the first pin. The second to fifth pins are control signal output terminals. The 6th pin is an input terminal for the dimming signal from the receiving unit 10a shown in FIG. The voltage dividing value of the voltage Vla applied to the light emitting element 8a is input to the seventh pin by the voltage dividing circuit 13b including the resistors R4 and R5 connected in series. The A / D converter 13c is connected to the 7th pin, converts an input value into a digital signal for internal processing, and outputs the digital signal to the arithmetic unit 13e. The 8th pin is grounded.

  FIG. 5 shows a processing flow executed by the calculation unit 13e. In response to power-on, in step # 1, initialization processing is executed. In step # 2, an ON signal having a period determined according to the dimming signal is output from the second pin, and the PWM dimming signal generation circuit 12a is caused to generate a PWM dimming signal having a duty ratio determined according to the dimming signal. . Thereby, the light emitting element 10a emits light. In Step # 3, a light emitting element initial lighting process for performing constant current control to the light emitting element 8a based on an input value to the 7th pin is performed. In step # 4, the voltage Vla applied to the light emitting element 8a is measured based on the input value to the 7th pin and stored in the storage unit 13d. The measurement is performed by detecting the voltage input to the 7th pin at an extremely short period sufficient to detect and process an abnormality, for example, a period of 10 ms.

  In Step # 5, when the value of the light emitting element voltage Vla is not more than the upper limit value Vth1 and not more than the lower limit value Vth2 (No in Step # 5), the process proceeds to Step # 10. In step # 10, an ON signal is output from the third pin, the potential of the signal output from the PWM dimming signal generation circuit 12a is set to 0 V, the circuit is stopped, and then the process ends. As described above, when the rated voltage of the light emitting element 8a is 7.5V, the upper limit value Vth1 is, for example, 10 and several V, and the lower limit value Vth2 is, for example, several V. By performing the above processing, when a short circuit or an open circuit occurs in the circuit and the voltage applied to the light emitting element 8a exceeds the upper limit value or falls below the lower limit value, the power supply to the light emitting element 8a is stopped. The light emitting element 8a and the circuit can be protected. The arithmetic unit 13e performs the steps # 5 and # 10 to stop the current supplied to the light emitting element when an abnormality occurs due to the short circuit or the open circuit of the light emitting element 8a, thereby protecting the light emitting element 8a and the circuit. Function as.

  In step # 5, when the value of the light emitting element voltage Vla is not more than the upper limit value Vth1 and not less than the lower limit value Vth2 (Yes in step # 5), the process proceeds to the next step # 6. In Step # 6, a light emitting element steady lighting process for performing constant current control to the light emitting element 8a based on an input value to the 7th pin is performed.

  In step # 7, based on the voltage detection result stored in the storage unit 13d, the slope of the voltage change (| ΔVla | / t (for example, t = for example) every 100 ms is short enough to detect and process the abnormality. 100 ms)). For example, if it is every 100 ms, the inclination is calculated from the change ΔVla for 10 potential detections performed every 10 ms in step # 4.

  In step # 8, when the inclination obtained in step # 7 is equal to or less than the threshold value α (Yes in step # 8), the above steps # 4 to step are performed until the light emitting element 8a is detected to be turned off (No in step # 9). The process of # 8 is repeatedly executed. The threshold value α is a value larger than the value detected during operation within the rated range, and is set to a value that can best detect the occurrence of an abnormality due to the partial destruction of the light emitting element 8a from actual statistical data. The value detected during operation within the rated range is, for example, a value that represents the amount of change in voltage that occurs due to a temperature change in a set environment during operation within the rated range. When the environmental temperature changes from 37 degrees to 60 degrees, the amount of change varies depending on the period T required for the change, but is, for example, −10.3 mV | / sec. When the obtained inclination exceeds the threshold α (No in Step # 8), or when it is confirmed that the light emitting element 8a is turned off (Yes in Step # 9), the process proceeds to Step # 10. In step # 10, an ON signal is output from the third pin, the potential of the signal output from the PWM dimming signal generation circuit 12a is set to 0 V, the circuit is stopped, and then the process ends.

  FIG. 6 is a diagram showing a change in voltage (initial voltage V0) applied to the light emitting element 8a during several tens of seconds after lighting. In this figure, the amount of change in voltage applied to the light emitting element 8a up to t1 (for example, | −2.23 mV | / sec) is due to temperature change that occurs in a set environment. The threshold value α is a value (for example, α = | −100 mV |) that can detect a value (for example, | −158 mV | / sec) that appears at the time of occurrence of an abnormality, which has a larger amount of change than the slope caused by the temperature change with the passage of time. / sec). At t1, the light emitting element 8a was partially broken by applying an impact from the outside. As shown in the figure, the internal resistance of the light emitting element 8a is greatly reduced in a short period (about 2 seconds) from t1 (for example, 10 seconds) to t2 (for example, 12 seconds). As a result, the voltage is | -100 mV | / sec. It greatly decreased with a larger change amount (for example, | -158 mV | / sec). In this case, by executing the process of Step # 8, it is possible to detect half-breakage of the light emitting element 8a and stop the current flowing through the light emitting element 8a. As described above, in step # 10, an ON signal may be output from the 4th pin to significantly reduce the current flowing through the light emitting element 8a.

  Note that in the general organic EL light emitting element, the initial voltage V0 increases with deterioration over time. If the initial voltage increases to a threshold value Vth1 (upper limit value: for example, 120% of the voltage V0) larger than the preset voltage V0 by elapse of a predetermined time (for example, 10000 hours), the step # 5 , # 10 is executed, the light emitting element 8a is replaced.

  Further, in step # 8, a threshold value α1 (for example, α1 = | −100 mV | / sec) and α2 (for example, α2 = | −150 mV | / sec) may be used. In this case, when the change amount is not less than the threshold value α1 and less than α2 (for example, −120 mV | / sec), an ON signal is output from the fourth pin in step # 10, and when the change amount is not less than α2 (for example, −−). 158 mV | / sec), an ON signal is output from the third pin in step # 10. Thereby, circuit protection processing according to the degree of occurrence of abnormality can be performed.

  The calculation unit 13e of the control IC 13a performs the processes of steps # 8 and # 10, so that when the light-emitting element 8a is partially destroyed during use and the internal resistance changes suddenly, the current supplied to the light-emitting element is changed. It functions as a protective means for protecting the light emitting element 8a and the peripheral circuit by reducing or stopping.

  By using the lighting device 9a having the above-described configuration, the light emitting element 8a is partially broken during use, and the internal resistance rapidly changes. Even when the subsequent potential is not a value representing a short circuit or an open circuit, the protective means is Operates to reduce or stop the current supplied to the light emitting element. Thus, the semi-broken light emitting element 8a and peripheral circuits are protected.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, the value of the threshold α is preferably set to a value larger than the potential change that can occur due to the temperature change that occurs in the actual use situation in consideration of the temperature change associated with the seasonal change as the setting environment. In addition, although the resistance value of the organic EL light emitting element decreases due to half breakdown, the resistance value of the light emitting element lighting device of the present invention increases due to half breakdown, but the increased value does not exceed the upper limit value indicating the opening of the circuit. It can also be used for a light-emitting element.

  In the present invention, as in the case of an organic EL light emitting device, an abnormality such as “half-destruction” may occur in which the internal voltage is changed in addition to a short circuit or open circuit, but the subsequent voltage does not become a value indicating a short circuit or open circuit. It can be used for a light emitting element.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Light emission part 2a Light emission panel 5 Power supply unit 6, 7 Light emission unit 8a Organic EL light emitting element 9a Light emitting element lighting device 11 Drive voltage Vcc generation circuit 12 Signal generation circuit 13 Control part

Claims (6)

In a light emitting element lighting device for lighting an organic EL light emitting element,
A current control unit for controlling a current flowing through the light emitting element to be constant;
A voltage detector for detecting a voltage across the light emitting element,
The current control unit calculates a voltage change amount per unit time of the voltage detected by the voltage detection unit, and sets a threshold value that is larger than a value detected when the calculated change amount is operated within a rated range. If exceeded, reduce or stop the amount of current flowing to the light emitting element,
The light emitting element lighting device characterized by the above-mentioned.   The light emitting element lighting device according to claim 1, wherein the threshold value is set to a value larger than a change amount of a voltage caused by a temperature change in a setting environment.   The current control unit further stops a current flowing through the light emitting element when the voltage detected by the voltage detection unit falls below a lower limit value or exceeds an upper limit value. Or the light emitting element lighting device of Claim 2.   The current control unit generates a PWM dimming signal having a duty ratio determined according to an input dimming signal, and causes a PWM current to flow through the light emitting element based on the signal. Item 4. The light-emitting element lighting device according to any one of Items 1 to 3.   One or more organic EL light emitting elements, the light emitting element lighting device according to any one of claims 1 to 4 for lighting each light emitting element, and a power supply unit for supplying power to the light emitting element lighting device A lighting device comprising: a light-emitting panel.   The said current control part produces | generates the PWM dimming signal of the duty ratio defined according to the dimming signal input from the outside, and performs current control based on this signal, It is characterized by the above-mentioned. Lighting equipment.

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