JP2012221871A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device which can relatively accurately indicate end of life of a solid-state light emitting element.SOLUTION: A lighting device comprises: a light source driving unit 2 for generating direct current power for lighting a solid-state light emitting element 1; and a lifetime determining unit 3 for determining whether or not the solid-state light emitting element is at the end of life. The lifetime determining unit 3 determines whether or not the solid-state light emitting element 1 is at the end of life based on electrical properties of the solid-state light emitting element 1 during a period in which the solid-state light emitting element 1 is off. When the solid-state light emitting element 1 is determined to be at the end of life, a control unit 4 controls the light source driving unit 2 so that the end of life is indicated through a lighting state of the solid-state light emitting element 1. Since the end of life is determined based on a detection result of the electrical properties of the solid-state light emitting element 1, variation and difference in operating environment of the solid-state light emitting element 1 are considered compared with a case in which the end of life is determined based only on cumulative lighting time of the solid-state light emitting element 1. Thus it is possible to relatively accurately indicate the end of life of the solid-state light emitting element 1.

Description

  The present invention relates to a lighting fixture.

  Conventionally, in lighting fixtures that turn on an electrical light source, when the cumulative lighting time of the light source reaches a predetermined time, a user is informed of the end of the life of the light source and prompted to replace the light source. (For example, refer to Patent Document 1).

  In such a luminaire, a user who has confirmed the notification replaces the light source, which may cause excessive electrical stress on the circuit components due to aging of the light source, and the light source will not turn on without prior notice. This avoids inconvenience for the user.

JP 2001-185374 A

  However, when the end of life of the light source is simply determined based on the cumulative lighting time as described above, the accuracy of the notification is low because the difference in the degree of aging due to the variation in the light source and the difference in the usage environment is not reflected. .

  In particular, in the case of a solid state light emitting device, the lifetime is longer than that of other light sources, and therefore, the cumulative lighting time at which the degree of aging deterioration becomes constant is likely to vary greatly depending on the use environment.

  This invention is made | formed in view of the said reason, The objective is to provide the lighting fixture which can alert | report the end of life of a solid light emitting element comparatively correctly.

  The lighting apparatus of the present invention includes a light source driving unit that generates direct-current power for turning on a solid light emitting element, and detecting an electrical characteristic of the solid light emitting element while the solid light emitting element is turned off, and based on the electrical characteristic. A life determination unit that determines whether or not the solid light-emitting element is at the end of its life, and a notification unit that notifies a user when the end of life of the solid light-emitting element is determined by the life determination unit, To do.

  In this lighting fixture, the life determination unit may detect the electrical characteristics after the power supply is started and before the light source driving unit starts lighting the solid state light emitting device.

  In the above luminaire, the light source driving unit can perform an intermittent lighting operation that alternately repeats a lighting period in which the solid state light emitting element is turned on and a light emitting period in which the solid state light emitting element is turned off. The unit may detect the electrical characteristics during the extinguishing period.

  Furthermore, in the above-described lighting apparatus, the life determination unit may detect an impedance of the solid state light emitting element as the electrical characteristic.

  Further, in the above-described lighting fixture, the time counting unit that measures the cumulative lighting time of the solid state light emitting element, and the estimated value of the cumulative lighting time that is determined by the lifetime determining unit that the solid state light emitting element is at the end of the lifetime, An estimated life calculation unit that calculates the electrical characteristic detection result in the life determination unit and a cumulative lighting time when the detection result is obtained using a plurality of times, and an estimated life notification unit that notifies the estimated value You may prepare.

  According to the present invention, since the end of life is determined based on the detection result of the electrical characteristics of the solid state light emitting device, the solid state is compared with the case where the end of life is determined based only on the cumulative lighting time of the solid state light emitting device. Reflecting the variation in the light emitting elements and the difference in the usage environment, the end of life of the solid light emitting elements can be reported relatively accurately. In addition, since the detection of the electrical characteristics of the solid state light emitting element and the determination of whether or not it is at the end of the life are performed while the solid state light emitting element is extinguished, compared to the case where the above detection and determination are performed while the solid state light emitting element is turned on. The end of life of the solid state light emitting device can be notified more accurately.

It is a block diagram which shows Embodiment 1 of this invention. It is a circuit diagram which shows the equivalent circuit of the solid light emitting element used for the same as the above. It is explanatory drawing which shows an example of the waveform of the voltage applied to a solid light emitting element same as the above. It is explanatory drawing which shows the relationship between the cumulative lighting time of the solid light emitting element used for the above, and the equivalent capacitance Cp. It is explanatory drawing which shows an example of the waveform of the voltage applied to a solid light emitting element when it determines with a solid light emitting element being the end of life in the same as the above. It is explanatory drawing which shows the relationship between the cumulative lighting time of the solid light emitting element used for Embodiment 2 of this invention, and the phase angle of an impedance. It is a block diagram which shows the example of a change same as the above. It is explanatory drawing which shows an example of the waveform of the voltage applied to a solid light emitting element in another modified example same as the above. It is explanatory drawing which shows the relationship between the cumulative lighting time of the solid light emitting element used for the example of FIG. 8, and the phase angle of an impedance.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, the present embodiment includes a light source driving unit 2 that generates DC power for lighting the solid state light emitting device 1, a life determining unit 3 that determines whether or not the solid state light emitting device is at the end of its life, and light source driving. The control part 4 which controls the part 2 is provided.

  As the solid-state light emitting element 1, an organic EL or the like is known in addition to a light emitting diode.

  The light source driving unit 2 includes, for example, a rectifying / smoothing circuit that rectifies and smoothes AC power input from the outside, and a DC power source that performs a feedback operation so as to supply a constant current to the solid-state light emitting device 1 using the rectifying / smoothing circuit as a power source. A circuit (for example, a well-known buck converter).

  In the present embodiment, the life determination unit 3 detects the electrical characteristics of the solid state light emitting element 1 while the solid state light emitting element 1 is turned off, and whether the solid state light emitting element 1 is at the end of its lifetime based on the detected electrical characteristics. It is characterized by determining whether or not.

  Specifically, for example, the solid state light emitting device 1 includes a parallel circuit of a capacitor (hereinafter referred to as “parallel capacitor”) Cp and a resistor (hereinafter referred to as “parallel resistor”) Rp as shown in FIG. And a resistor (hereinafter referred to as “series resistor”) Rs. The life determination unit 3 detects the capacitance of the parallel capacitor Cp (hereinafter referred to as “equivalent capacitance Cp”) and the resistance value of the parallel resistor Rp (hereinafter referred to as “equivalent resistance Rp”).

  The above-described detection by the life detection unit 3 is performed after the power supply is started by turning on the power and before the light source driving unit 2 starts lighting the solid state light emitting element 1. At the time of the above detection, a voltage obtained by superimposing an AC voltage on a DC voltage (hereinafter referred to as “detection voltage”) is input (applied) to the solid-state light emitting element 1 as in the detection period Td shown in FIG. Is done. The minimum value of the detection voltage is increased to such an extent that a current flows through the solid state light emitting element 1, and the maximum value of the detection voltage is decreased to an extent that the solid state light emitting element 1 does not light up. The circuit for generating the detection voltage as described above may be provided in the life determination unit 3, or the light source driving unit 2 controlled by the control unit 4 may generate the detection voltage.

Here, for the solid light-emitting element of the same type as the solid-state light-emitting element 1 of the present embodiment, a graph with the equivalent capacitance Cp on the vertical axis and the cumulative lighting time on the horizontal axis is shown in FIG. FIG. 4 shows a cumulative lighting time (hereinafter referred to as “light emission”) in which a leakage current (that is, a current that does not contribute to light emission) increases rapidly during measurement and the luminous flux rapidly decreases to 70% or less immediately after manufacturing. Called “lifetime.”) Tx is also shown. In FIG. 4, the cumulative lighting time at which the equivalent capacitance Cp starts to rise substantially matches the above-described lifetime tx. From this, the lifetime determination part 3 of this embodiment determines with the solid light emitting element 1 being the end of lifetime, when the equivalent capacitance Cp becomes more than a predetermined reference | standard equivalent capacitance. As the above-mentioned reference equivalent capacitance, a fixed value (for example, 5.0 × 10 ⁻¹⁰ F) may be used, and a predetermined coefficient (for example, 1.2) is added to the equivalent capacitance Cp obtained by the first detection after shipment. ) May be used.

  Further, according to the experiment of the present inventor, the equivalent resistance Rp has a correlation with the light flux of the solid state light emitting device 1 and monotonously decreases with respect to the cumulative lighting time. Therefore, in the present embodiment, the equivalent resistance Rp when the luminous flux is reduced to 70% immediately after manufacture in a measurement performed in advance using a solid light emitting element of the same type as the solid light emitting element 1 is used as a reference equivalent resistance. 3 is stored. The life determination unit 3 determines that the solid state light emitting device 1 is at the end of its life even when the equivalent resistance Rp is less than the reference equivalent resistance. Instead of setting the reference equivalent resistance to the fixed value as described above, a value obtained by multiplying the equivalent resistance Rp detected first after shipment by a predetermined coefficient may be used as the reference equivalent resistance.

  That is, the life determination unit 3 determines the end of life of the solid state light emitting device 1 by the logical sum of the determination based on the equivalent capacitance Cp and the determination based on the equivalent resistance Rp.

  The life determination unit 3 determines that the solid state light emitting device 1 is not at the end of life only when the equivalent capacitance Cp is less than the reference equivalent capacitance and the equivalent resistance Rp is equal to or greater than the reference equivalent resistance. When the life determination unit 3 determines that the solid light emitting element 1 is not at the end of its life, the control unit 4 turns on the solid light emitting element 1 with a predetermined light output (for example, rated to the solid light emitting element 1). The light source drive unit 2 is controlled so that current is continuously input.

  When the end of life is determined by the life determination unit 3, the control unit 4 indicates that the solid state light emitting device 1 is at the end of life for a predetermined time (for example, 10 seconds) immediately after the start of lighting of the solid state light emitting device 1. The light source driving unit 2 is controlled so that the notification lighting is performed. Specifically, the notification lighting is, for example, blinking the solid-state light emitting element 1 at a frequency low enough to be recognized as blinking by human eyes (for example, 0.5 Hz). An example of the waveform of the voltage applied to the solid state light emitting device 1 in this case is shown in FIG. That is, the end of life is notified by the lighting state of the solid state light emitting element 1, and the solid state light emitting element 1 is also used as an informing unit. Further, after the notification lighting, the light source driving unit 2 continuously outputs the rated current to the solid light emitting element 1 to continuously light the solid light emitting element 1.

  In addition to the solid state light emitting device 1, a notification unit (not shown) including a display unit that displays the end of life and a driving unit that drives the display unit according to the control of the control unit 4 is provided. Instead of lighting, or together with the above-described lighting for notification, notification by display on the above display means may be performed. For example, a light emitting element or a liquid crystal panel can be used as the display means, and the driving means can be realized by a known electronic circuit.

  Further, when it has a communication unit (not shown) that transmits / receives a wired signal or a wireless signal to / from an external device (not shown) such as a remote controller, when the end of life is determined by the life determination unit 3 The control unit 4 may control the communication unit to transmit an appropriate signal to the external device so that the end of life is notified by the external device. In this case, the communication unit is a notification unit.

  According to the above configuration, since the end of life is determined based on the detection result of the electrical characteristics of the solid state light emitting device 1, compared to the case where the end of life is determined based only on the cumulative lighting time of the solid state light emitting device 1. By reflecting the variation in the solid light emitting element 1 and the difference in use environment, the end of life of the solid light emitting element can be reported relatively accurately.

  Here, in the solid-state light emitting element 1, the electrical characteristics such as the equivalent capacitance Cp, the equivalent resistance Rp, and the impedance are different values during lighting and during extinguishing, and the change in the electrical characteristics due to aging deterioration is as follows. It is larger when it is not lit than when it is lit. In the present embodiment, the detection of the electrical characteristics of the solid state light emitting element 1 and the determination as to whether or not the end of the lifetime is made are performed while the solid state light emitting element 1 is turned off. Compared with the case where it is performed, the end of life of the solid state light emitting device can be notified more accurately.

  The life determination unit 3 may determine the end of life based on only one of the equivalent capacitance Cp and the equivalent resistance Rp.

(Embodiment 2)
Since the basic configuration of the present embodiment is the same as that of the first embodiment, description of the common parts is omitted.

  The difference between the present embodiment and the first embodiment resides in the life determination unit 3, and the electrical characteristic detected by the life determination unit 3 in this embodiment is the impedance of the solid state light emitting device 1.

  FIG. 6 shows a graph in which the phase angle of impedance of the solid state light emitting device 1 is taken on the vertical axis and the cumulative lighting time of the solid state light emitting device 1 is taken on the horizontal axis. Here, when the resistance (the real part of impedance R + jX) R and the reactance (the imaginary part of impedance R + jX) X of the solid state light emitting element 1 are used, the above phase angle is Arctan (X / R). expressed.

  The life determination unit 3 of the present embodiment determines that the solid state light emitting device 1 is at the end of its life when the above phase angle reaches a predetermined reference phase angle. The reference phase angle is the phase angle of the impedance when the leakage current increases rapidly in a measurement performed in advance using a solid-state light-emitting element of the same type as the solid-state light-emitting element 1 (that is, in the case of the measurement performed in advance) Is the phase angle when the cumulative lighting time reaches the life time tx, which is about 0 ° in the example of FIG. In addition, you may make it alert | report earlier by making said reference | standard phase angle into a smaller value (for example, -5 degrees). Here, since the reactance generally depends on the frequency of the applied voltage, the relationship between the phase angle and the cumulative lighting time also differs depending on the frequency of the detection voltage. Therefore, the frequency of the detection voltage in the present embodiment is made equal to the frequency of the detection voltage used in the measurement for determining the reference phase angle.

  Further, according to the experiments by the present inventors, the resistance of the solid state light emitting element 1 has a correlation with the light flux of the solid state light emitting element 1 and monotonously decreases with respect to the cumulative lighting time. Therefore, the lifetime determination unit 3 of the present embodiment determines that the solid state light emitting device 1 is at the end of its lifetime even when the resistance of the solid state light emitting device 1 is less than a predetermined reference resistance. As the reference resistance, for example, the resistance when the luminous flux is reduced to 70% immediately after manufacturing in a measurement performed in advance using a solid light emitting element of the same type as the solid light emitting element 1 is used. Alternatively, a value obtained by multiplying a resistance detected first after shipment by a predetermined coefficient may be used as the reference resistance.

  That is, the life determination unit 3 of the present embodiment determines the end of life of the solid-state light emitting device 1 by the logical sum of the determination based on the phase angle and the determination based on the resistance. In other words, the lifetime determination unit 3 of the present embodiment is configured so that the solid-state light-emitting element 1 has a phase angle of impedance of the solid-state light-emitting element 1 that is less than the reference phase angle and the resistance of the solid-state light-emitting element 1 is greater than or equal to the reference resistance. It is determined that 1 is not the end of life.

  The determination as to whether the solid state light emitting device 1 is at the end of its life may be made based on only one of the phase angle and the resistance. Further, the reactance of the solid state light emitting device 1 can be used for the above determination in the same manner as the phase angle.

  Furthermore, in each of the above-described embodiments, as shown in FIG. 7, as a time measuring unit 5 that measures the cumulative lighting time of the solid state light emitting device 1 and an estimated life notification unit that displays an estimated value of the lifetime of the solid state light emitting device 1. A display unit 6 may be provided. The estimated value is an estimated value of the cumulative lighting time that is determined by the lifetime determination unit 3 that the solid state light emitting device 1 is at the end of its lifetime. The calculation of the estimated value is performed by the control unit 4 by using the electrical characteristic detection result in the life determination unit 3 and the accumulated lighting time when the detection result is obtained for a plurality of times. That is, the control unit 4 is an estimated life calculation unit. Since the time measuring unit 5 can be realized by a well-known technique using, for example, a crystal resonator, detailed illustration and description thereof are omitted. As the display unit 6, for example, a known display device such as a liquid crystal panel can be used. The display unit 6 may also serve as a notification unit that notifies the end of life of the solid state light emitting device 1. Further, when a communication unit (not shown) for transmitting and receiving signals to and from an external device (not shown) such as a remote controller is provided, a signal instructing display of the estimated value is sent to the external device. In addition, the control unit 4 may control the communication unit at an appropriate timing. In this case, the communication unit is an estimated life notification unit.

  As an operation in which the control unit 4 calculates the estimated value of the lifetime of the solid state light emitting device 1, for example, the relationship between the resistance and the cumulative lighting time in the past multiple detections (for example, three times) in the lifetime determination unit 3 is appropriately selected. In the obtained function, the cumulative lighting time at which the resistance reaches the reference resistance is calculated, and the cumulative lighting time (calculated value) obtained by this calculation is used as the lifetime of the solid state light emitting device 1. Estimated value of The above operation may be performed using other electrical characteristics such as equivalent resistance Rp instead of resistance. Further, according to the experiments by the present inventors, when the frequency of the detection voltage is set to several tens of Hz, the phase angle changes linearly with respect to the cumulative lighting time until the lifetime tx as shown in FIG. It is also possible to calculate an estimated value of the lifetime of the solid state light emitting device 1 using the phase angle in the same manner as described above.

  Or the control part 4 may compare said calculated value with the fixed value memorize | stored at the time of manufacture, and may display a smaller thing on the display part 6 as an estimated value of a lifetime. As the fixed value, for example, the cumulative lighting time when the luminous flux is reduced to 70% immediately after manufacturing in an experiment performed in advance using a solid light emitting element of the same type as the solid light emitting element 1 is used.

  Further, the timing at which the life determination unit 3 operates is not limited to the above. For example, as illustrated in FIG. 8, the light source driving unit 2 performs an intermittent lighting operation in which a lighting period T <b> 1 in which the solid state light emitting element 1 is turned on and a light emitting period T <b> 2 in which the solid state light emitting element 1 is extinguished alternately. In such a case, the detection of electrical characteristics and the determination of the end of life by the life determination unit 3 may be performed during the turn-off period T2. In this case, it is desirable that the period of the detection voltage is shorter than the duration of each extinguishing period T2. For example, when the cycle of the intermittent lighting operation is 2000 Hz and the on-duty is 50%, the frequency of the detection voltage is 4000 Hz or more. When the frequency of the detection voltage is 5000 Hz, the relationship between the phase angle and the cumulative lighting time is as shown in FIG. 9, and the reference phase angle is, for example, −80 °. Here, the above-described operation by the life determination unit 3 is not necessarily performed in all the extinguishing periods T2, and may be performed only in one or a plurality of extinguishing periods T2 immediately after the power is turned on. It may be performed periodically such as every plural cycles of the lighting operation. In the example of FIG. 8, the first two extinguishing periods T2 are detection periods Td in which a detection voltage is input to the solid-state light emitting element 1 and it is determined whether or not it is the end of life. However, when a usage pattern in which the power is kept on for a long time is assumed, the detection of the electrical characteristics and the determination of whether or not the end of the life is reached are performed not only immediately after the power is turned on, but also periodically. Need to be

1 Solid-state light-emitting device (also serves as a notification unit)
2 Light source drive unit 3 Life determination unit 4 Control unit (estimated life calculation unit)
5 Timekeeping section 6 Display section (Estimated life notification section)

Claims (5)

A light source driving unit that generates DC power for lighting the solid state light emitting device;
A lifetime determination unit that detects electrical characteristics of the solid state light emitting element while the solid state light emitting element is turned off and determines whether the solid state light emitting element is at the end of its lifetime based on the electrical characteristics;
An illuminating device comprising: a notification unit that notifies a user when the end of life of the solid state light emitting device is determined by the lifetime determination unit. The light source driving unit is capable of intermittent lighting operation that alternately repeats a lighting period for turning on the solid state light emitting element and a light extinguishing period for turning off the solid state light emitting element,
The lighting apparatus according to claim 1, wherein the life determination unit detects the electrical characteristics during the extinguishing period.   The said life determination part performs the detection of the said electrical property, after the supply of electric power is started, but before the said light source drive part starts lighting of the said solid light emitting element. Item 3. A lighting apparatus according to item 2.   The lighting apparatus according to claim 1, wherein the life determination unit detects an impedance of the solid-state light emitting element as the electrical characteristic. A time measuring unit for measuring the cumulative lighting time of the solid state light emitting device;
The estimated value of the cumulative lighting time at which the solid-state light emitting element is determined to be at the end of the lifetime by the lifetime determination unit, the detection result of the electrical characteristics in the lifetime determination unit and the cumulative lighting when the detection result is obtained An estimated life calculation unit that calculates time using multiple times,
The luminaire according to any one of claims 1 to 4, further comprising an estimated life notification unit that notifies the estimated value.

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