JP2012094270A - Lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting apparatus that includes a plurality of plane-shaped light sources and in which the load to circuit components is reduced so as to have a long life span.SOLUTION: A lighting apparatus comprises a lighting device 1 that is connected to a commercial supply AC and a plurality of plane-shaped light sources 2 that is connected to the lighting device 1 and is lighted up by the supply of lighting power from the lighting device 1. Each of the plane-shaped light sources 2 includes, for example, an organic electroluminescence (EL) element, and each of the plane-shaped light sources is set so as to emit light with illumination in accordance with the duty ratio of the input lighting power. The plane-shaped light sources 2 are connected in series and have a low composite capacitance of the whole of the plane-shaped light sources 2, as compared to the case where the plane-shaped light sources 2 are connected in parallel.

Description

  The present invention relates to a lighting device having a planar light source.

  Generally, a self-luminous organic EL element has advantages such as low heat generation, light weight and thin design, low driving voltage, and power saving. An illuminating device using this organic EL element as a light source Is provided.

  In this type of lighting device, it is desired to illuminate a wide space such as a room. However, when the size of the organic EL element is increased, the film thickness of the organic light emitting layer constituting the organic EL element is uniformly formed. It was difficult to do this, and there was a risk of uneven light emission due to the resistance of the electrode material. Thus, there is provided an illumination device that illuminates a wide space by configuring a planar light source (planar light source) with small organic EL elements and connecting a plurality of the planar light sources in parallel (for example, Patent Documents). 1).

  In the lighting device described in Patent Document 1, a plurality of planar light sources composed of organic EL elements are connected to a pair of power supply rails to which a driving voltage from a lighting device is fed, so that the planar light source generates a driving voltage. Power is received and light is emitted. At this time, by arranging the feeding points from the lighting device to the feeding rails at symmetrical positions, the lengths of the electric paths from the lighting device to the respective planar light sources become equal, and uneven light emission is suppressed.

JP 2009-152009 A

  By the way, the planar light source composed of the organic EL element as described above generally has a large capacitance component. For this reason, in the illumination device as described in Patent Document 1, since a plurality of planar light sources are connected in parallel, the combined capacitance component increases, and the inrush current may increase. In particular, when a PWM (Pulse Width Modulation) power source is used to adjust the light output from the planar light source, an inrush current flows every PWM control cycle. As a result, there is a risk that the deterioration of the circuit components constituting the lighting device is accelerated and the life of the lighting device is shortened.

  The present invention has been made in view of the above-described reasons, and the object of the present invention is to provide a long-life lighting device that reduces the load on circuit components even when a plurality of planar light sources are arranged side by side. It is to provide.

  In order to achieve the above object, an illuminating device of the present invention includes a plurality of planar light sources, and a power source that includes either a DC power source or a PWM power source and supplies lighting power to the planar light source. A planar light source is connected in series.

  In this illumination device, a plurality of branch circuits in which a plurality of planar light sources are connected in series may be provided, and a plurality of branch circuits may be connected in parallel to the power source. In this case, the plurality of branch circuits may be electrically connected to at least one of the parts having the same potential.

  Moreover, in these illuminating devices, it is preferable to arrange | position the planar light source which comprises another branch circuit between several planar light sources which comprise each branch circuit.

  Furthermore, it is preferable to include a current detection unit that detects a current value flowing through the planar light source, and a control unit that stops the output of the power supply when the current value exceeds a predetermined threshold.

  The planar light source is preferably an organic EL element.

  According to the illumination device of the present invention, in an illumination device in which a plurality of planar light sources are arranged side by side, it is possible to provide a long-life illumination device by reducing the load on circuit components.

It is a schematic circuit diagram which shows the illuminating device concerning Embodiment 1 of this invention. It is a graph which shows the electric current value which flows through the planar light source which comprises the illuminating device. (A)-(c) is a schematic circuit diagram which shows the other examples of the same illuminating device, respectively. It is the schematic which shows arrangement | positioning of the planar light source in the illuminating device concerning Embodiment 2 of this invention. (A)-(c) is a schematic circuit diagram which shows the other examples of the same illuminating device, respectively.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, the lighting apparatus according to the present embodiment includes a lighting device 1 connected to a commercial power source AC1 and a plurality of planar light sources 2 that are lit by lighting power supplied from the lighting device 1. Prepare as an element.

  The lighting device 1 includes a diode bridge DB1, a PFC (power factor correction) circuit 10, and a PWM (Pulse Width Modulation) circuit 11 as its constituent elements. The PFC circuit 10 converts AC power that has been full-wave rectified by the diode bridge DB1 into DC power and outputs the DC power to the PWM circuit 11. Switching elements (not shown) constituting the PFC circuit 10 operate at tens to hundreds of kHz.

  The PWM circuit 11 converts the DC power input from the PFC circuit 10 into a pulse wave set to a predetermined duty ratio by switching, and outputs the pulse wave to each planar light source 2. Here, the duty ratio of the pulse wave may be appropriately set according to the number of planar light sources 2 to be connected, a desired light output level, and the like.

  The lighting device 1 includes a current detection circuit 3 that detects a current value flowing through the planar light source 2 and a detection current value (I in FIG. 2) detected by the current detection circuit 3 from the lighting device 1. A control circuit 4 for stopping output is connected. The current detection circuit 3 includes a resistor R connected between the PWM circuit 11 and the planar light source 2, and generates a voltage signal corresponding to the current value (detected current value I) flowing through the resistor R. The control circuit 4 includes a comparator CP1 that compares the level of the output from the current detection circuit 3 with the reference voltage, and is set to stop the PWM circuit 11 when the input voltage value becomes larger than the reference voltage.

  An example of the detected current value I detected by the current detection circuit 3 is shown in FIG. As shown in FIG. 2, the combined capacitance component of the planar light source 2 connected to the PWM circuit 11 causes a current (inrush current) larger than the current value (Iav in the figure) during stable operation for each PWM control cycle. ) Flows (Iin in FIG. 2). When the current value detected by the current detection circuit 3 is larger than a predetermined current threshold (Ith in FIG. 2), that is, when the output from the current detection circuit 3 is larger than the reference voltage, the control circuit 4 The operation of the PWM circuit 11 is stopped.

  The planar light source 2 is, for example, an organic EL element formed in a rectangular plate shape, and emits light with illuminance corresponding to the duty ratio of input lighting power. Here, each planar light source 2 utilizes the same various performances such as the relationship between illuminance (fermentation efficiency), size and shape with respect to the input lighting power. Each planar light source 2 is electrically connected in series, and each planar light source 2 is arranged adjacent to each other.

  Thereby, compared with the case where the planar light sources 2 are connected in parallel, the capacitance component of the entire planar light source 2 is reduced, so that the inrush current generated at each PWM control cycle by the lighting device 1 is reduced. Can do. As a result, the load on each circuit component constituting the lighting device can be reduced, and the life of the lighting device can be extended.

  In addition, when any planar light source 2 is short-circuited, the capacitance component of the entire planar light source 2 may increase and the inrush current may increase, but in the present embodiment, the current value If I is larger than a predetermined current threshold Ith, the output from the lighting device 1 is stopped. Thereby, it can prevent that a big electric current flows into each circuit component, and can reduce the load to each circuit component.

  In the present embodiment, AC power is converted to DC power using the PFC circuit 10, but AC power may be converted to DC power using a step-down / boost chopper circuit or the like. Further, instead of being connected to the commercial power source AC, it may be directly connected to a DC power source.

  Further, a step-down circuit such as a step-down chopper, a step-up chopper, a step-down step-up chopper circuit, or the like is used instead of the PWM circuit 11 that adjusts the light output of the planar light source 2 by performing PWM control based on the output from the PFC circuit 10. It may be. In this case, the output current value and voltage value may be appropriately set according to the number of connected planar light sources 2 and a desired light output level. Moreover, you may use the DC power supply with which output electric power was preset.

  As shown in FIG. 3A, branch circuits br1 and br2 each having a plurality of planar light sources 2 connected in series may be connected in parallel. In this way, even if one of the branch circuits br1 and br2 is damaged, the other branch circuit br can be turned on.

Further, as shown in FIG. 3B, branch circuits br1 and br2 each having a plurality of planar light sources 2 connected in series are connected in parallel, and the parts (points P ₁ and P 2) having the same potential in the branch circuits br1 and br2 ₂ ) may be electrically short-circuited. In this way, even if any planar light source 2 is broken open, for example, the lighting device is turned on without turning off all the planar light sources 2 in the same branch circuit br1, br2. Can continue. Further, by short-circuiting the same potentials of the branch circuits br1 and br2, the light output from each planar light source 2 can be made the same, and light unevenness can be reduced. Further, as shown in FIG. 3C, all the parts of the same branch circuit br1, br2 having the same potential are short-circuited, and even if any one of the planar light sources 2 is damaged, the remaining planar light sources 2 are connected. You may set it so that it can be lit.
(Embodiment 2)
As shown in FIG. 4, the lighting apparatus according to the present embodiment includes a branch circuit br1 in which planar light sources 2 _1a to 2 _1d are connected in series and a branch circuit in which planar light sources 2 _2a to 2 _2d are connected in series. with br2. Further, lighting devices 1a and 1b that are connected to the branch circuits br1 and br2 and supply lighting power to the branch circuits br (br1 and br2) are provided. The arrangement of the planar light source 2 in FIG. 4 shows the arrangement in the actual construction state, and is arranged in a 2 × 4 matrix, and the planar light sources 2 constituting the branch circuits br1 and br2, respectively. Are arranged alternately. That is, between the planar light source 2 _1a to 2 _1d constituting a branch circuit br1, the planar light source 2 _2a to 2 _2d constituting the branch circuit br2 is arranged. Except for this point, the configuration is the same as that of the first embodiment, so the common components are denoted by the same reference numerals and description thereof is omitted.

  This prevents light from being biased to one side of the lighting device when the lighting circuit 1 connected to any branch circuit br is damaged or when any planar light source 2 is broken open. Can do. Further, when the light output is determined by the magnitude of the supplied current, such as when an organic EL element is used as the planar light source 2, the light output from the planar light source 2 may be different for each connected lighting light source 1. Even in this case, it is possible to prevent the light from being biased to one side.

When four planar light sources 2 _1a to 2 _1d and 2 _2a to 2 _2d are arranged in a row, the planar light sources 2 of different branch circuits br are adjacent to each other as shown in FIG. Arrange them alternately. By alternately arranging the planar light sources 2 of the different branch circuits br, even when one of the branch circuits br is turned off or the light output is different for each branch circuit br, the light bias can be reduced. Further, since each light source branch br is connected in parallel to the same lighting device 1, the current value flowing through each branch circuit br may vary depending on the individual difference for each planar light source 2, but different branch circuits br have different values. Since the planar light sources 2 are alternately arranged, it is possible to reduce the light bias of the illumination device.

A branch circuit br in which four planar light sources 2 (2 _1a to 2 _1e ) are connected in series and a branch circuit br in which five planar light sources 2 (2 _2a to 2 _2d ) are connected in series are arranged in a 3 × 3 matrix. When arranged in a shape, they may be arranged as shown in FIG. Similarly, three planar circuits br each having three planar light sources 2 _1a to 2 _1c , 2 _2a to 2 _2c , and 2 _3a to 2 _3c connected in series are connected in parallel and arranged in a 3 × 3 matrix. In order to do so, it may be arranged as shown in FIG. That is, by determining the arrangement so as not to be adjacent to the planar light source 2 constituting the different branch circuits br vertically and horizontally, one of the branch circuits br is turned off, or the light output is different for each branch circuit br. Even in this case, the light bias can be reduced.

  In the present embodiment, the rectangular planar light source 2 is used. However, this does not limit the shape of the planar light source 2, and may be a polygon such as a triangle or a hexagon. (See FIG. 5 (d)).

DESCRIPTION OF SYMBOLS 1 Lighting device 2 Planar light source 3 Current detection circuit (current detection part)
10 PFC circuit 11 PWM circuit

Claims (6)

  A plurality of planar light sources, and a power source that is either a DC power source or a PWM power source and supplies lighting power to the planar light source, and the plurality of planar light sources are connected in series to the power source. Lighting device.   The lighting device according to claim 1, further comprising a plurality of branch circuits in which a plurality of planar light sources are connected in series, wherein the plurality of branch circuits are connected in parallel to the power source.   The lighting device according to claim 2, wherein at least one of the plurality of branch circuits is electrically connected among parts having the same potential.   The said planar light source which comprises the other said branch circuit is arrange | positioned between the said several planar light sources which comprise each said branch circuit, The Claim 2 or 3 characterized by the above-mentioned. Lighting device.   5. The apparatus according to claim 1, further comprising: a current detection unit that detects a current value flowing through the planar light source; and a control unit that stops the output of the power supply when the current value exceeds a predetermined threshold. The lighting device according to any one of the above.   The lighting device according to claim 1, wherein the planar light source is an organic EL element.

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