JP4826412B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device using a solid light emitting element as a light source.

2. Description of the Related Art Conventionally, light emitting devices using a solid light emitting element such as a light emitting diode as a light source have been provided. As a lighting control method for such a light emitting device, for example, a direct current lighting control method (for example, see Patent Document 1) in which a direct current voltage obtained by rectifying and smoothing an alternating current voltage is applied to a solid state light emitting element, and an alternating current voltage is rectified and smoothed. A switching lighting control system (see, for example, Patent Document 2) in which a rectangular wave voltage obtained by boosting a DC voltage and switching the boosted DC voltage at a high frequency is applied to a solid state light emitting element, and a fixed AC light emission. There is known a pulse lighting control method in which lighting is performed using only a predetermined section in one cycle of an AC voltage applied to an element. In recent years, traffic signals using light-emitting diodes as light sources have been widely used in place of conventional traffic signals using light bulbs as light sources. Light-emitting devices used in such traffic signals are easy to use due to the small number of parts. A pulse lighting control system that can be downsized and has a low failure rate is used.
JP 2006-73637 A Japanese Patent Laid-Open No. 11-67471

  By the way, in recent years, a drive recorder that is mounted on a car such as a taxi and records a moment of a traffic accident with a video has been spreading. This drive recorder attaches a video camera to the windshield of an automobile and shoots the front, and records an image for a certain period when an impact such as sudden braking is applied to the automobile.

  However, when the conventional pulse lighting control method as described above is adopted for a traffic signal device, it is necessary to increase the number of light emitting diodes connected in series from the viewpoint of luminous efficiency, and the number of light emitting diodes connected in series. As the voltage required for lighting increases and there is a non-lighting period in which the light emitting diode does not light up in one cycle of the AC voltage, depending on the shooting interval and timing when shooting with a video camera such as the above drive recorder May not be able to recognize the lighting state. In contrast, the DC lighting control method has a non-lighting period and good luminous efficiency, but requires a smoothing capacitor. Depending on the size of the circuit, an electrolytic capacitor with a large capacity is required and the power factor is reduced. There was a problem.

  The present invention has been made in view of the above points, and an object thereof is to provide a high power factor light emitting device capable of shortening the non-lighting period with a simple circuit configuration.

  In order to achieve the above object, the invention according to claim 1 is connected to a light emitting section formed by connecting a plurality of series circuits in which a current limiting element and a plurality of solid state light emitting elements are connected in series, and an AC power source. And a lighting device that supplies a drive voltage to the light emitting unit by full-wave rectifying the AC voltage, and the light emitting unit has a non-lighting period of at least one series circuit solid-state light emitting element in the other series. It is characterized by being shorter than the non-lighting period of the solid state light emitting device of the circuit.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the light emitting section is characterized in that the number of solid state light emitting elements of at least one series circuit is smaller than the number of solid state light emitting elements of other series circuits.

  According to a third aspect of the present invention, in the second aspect of the present invention, the light emitting section is characterized in that the number of solid state light emitting elements of at least one series circuit is one.

  The invention of claim 4 is characterized in that, in the invention of claim 1, the light emitting section is connected to smoothing means for smoothing and outputting the drive voltage supplied from the lighting device by at least one series circuit.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the light emitting unit, the lighting device, and a lamp in which the light emitting unit and the lighting device are housed are provided.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the lamp has an opening for exposing the light emitting portion to the outside, and the solid-state light emitting element of the series circuit having a short non-lighting period is provided at the approximate center of the opening. It is arranged.

  According to a seventh aspect of the invention, in the invention of the fifth aspect, the lamp has an opening for exposing the light emitting portion to the outside, and a solid-state light emitting element of a series circuit having a short non-lighting period is arranged at the periphery of the opening. It is characterized by that.

  The invention according to claim 8 is the invention according to any one of claims 5 to 7, wherein the light emitting part, the lighting device, and the lamp are for traffic signals.

  According to the first to third aspects of the invention, since the number of solid state light emitting elements of some series circuits among the plurality of series circuits is smaller than the number of solid state light emitting elements of other series circuits, a simple circuit configuration is provided. Thus, a light-emitting device can be configured in which the non-lighting period is short and the power factor does not decrease.

  According to the invention of claim 4, since the solid-state light emitting device of the series circuit is always lit by supplying a voltage obtained by smoothing the drive voltage to only some of the series circuits, the entire series circuit is not effective. A light emitting device without a lighting period can be formed. Further, since the smoothing means is connected to only some of the series circuits, the circuit can be easily configured without reducing the power factor.

  According to the invention of claim 5, it is possible to realize a light emitting device having a lamp that exhibits the effect of any one of claims 1 to 4.

  According to invention of Claim 6, wiring can be made easy by arrange | positioning the series circuit containing the solid light emitting element with a short non-lighting period in the approximate center of an opening part.

  According to the seventh aspect of the present invention, by arranging the solid light emitting elements having a short non-lighting period at the periphery of the opening, it is possible to prevent an extreme difference from occurring in luminance variations in the opening.

  According to the eighth aspect of the present invention, when the traffic signal is photographed by the video camera of the drive recorder described in the above problem, the lighting state of the traffic signal can be recognized regardless of the photographing interval and timing of the video camera. .

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings. In the present embodiment, as shown in FIG. 1A, a plurality of first series circuits 10 formed by connecting a resistor R as a current limiting element and a plurality of light emitting diodes L1 in series, and resistors R and 1 A light-emitting unit 1 comprising a second series circuit 11 formed by connecting a plurality of light-emitting diodes L2 in series, and a full-wave rectified AC voltage connected to an AC power source AC to supply a drive voltage to the light-emitting unit 1 The light emitting unit 1 includes a first series circuit 10 connected in parallel, and a second series circuit 11 connected in parallel to the subsequent stage of the first series circuit 10.

  The lighting device 2 includes, for example, a diode bridge, and full-wave rectifies the AC voltage from the AC power supply AC, and outputs the rectified pulsating voltage V1 to the light emitting unit 1. The lighting device 2 may have another circuit configuration as long as the AC voltage is full-wave rectified.

  The light emitting unit 1 is formed by connecting a plurality of first series circuits 10 formed by connecting a resistor R and a plurality (n in this embodiment) of light emitting diodes L1 in series. A second series circuit 11 formed by connecting a resistor R and one light-emitting diode L2 in series is connected in parallel to the subsequent stage of the circuit 10. The light emitting diode L1 of the first series circuit 10 and the light emitting diode L2 of the second series circuit 11 are the same. The number of light emitting diodes L1 in the first series circuit 10 is such that the forward voltage Vf per light emitting diode L1, L2 is about 2V for red light emitting diodes and about 3.5V for blue / green light emitting diodes. Considering this, if the AC power supply AC is a commercial power supply with a power supply voltage of 100 V, it is desirable to connect 20 to 30 in series.

  The operation of this embodiment will be described below. As shown in FIG. 1B, the light emitting diode L1 of the first series circuit 10 is lit only when the pulsating voltage V1 is higher than the forward voltage n × Vf necessary for lighting the light emitting diode L1. Therefore, the lighting state and the non-lighting state are repeated alternately. On the other hand, the light emitting diode L2 of the second series circuit 11 is lit only when the pulsating voltage V1 exceeds the forward voltage Vf necessary to light the light emitting diode L2. Therefore, the light emitting diode L2 of the second series circuit 11 has a longer lighting period and almost no non-lighting period as compared with the light emitting diode L1 of the first series circuit 10, so that the non-lighting period can be shortened as a whole. it can. For example, when the present embodiment is used as a traffic signal and the traffic signal is photographed with a video camera, even if the light emitting diode L1 of the first series circuit 10 is not lit, the light emission of the second series circuit 11 is performed. Since the diode L2 is in the lighting state, the lighting state of the light emitting diode L2 can be recognized regardless of the shooting interval and timing of the video camera.

  Further, the input current Iin to the light emitting unit 1 represented by the sum of the load current I1 flowing through each first series circuit 10 and the load current I2 flowing through the second series circuit 11 is the load current I2 Since it is smaller than the sum of the load currents I1 flowing through the series circuit 10, a high power factor can be maintained with almost no influence of the load current I2.

  As described above, the non-lighting period can be shortened by a simple circuit configuration in which the second series circuit 11 including the resistor R and one light-emitting diode L2 is added, and it is high without reducing the power factor. Power factor can be maintained.

    In the present embodiment, only one second series circuit 11 is provided. However, the number of circuits is not limited to one, and a plurality of second series circuits 11 may be used as long as the above-described effect can be obtained. A series circuit 11 may be provided. In the present embodiment, the number of the light emitting diodes L2 in the second series circuit 11 is one, but the number is not limited to this, and the number of the light emitting diodes L1 in the first series circuit 10 is less than the number. A plurality of light emitting diodes L2 may be used.

(Embodiment 2)
Embodiment 2 of the present invention will be described below with reference to the drawings. However, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 2A, the present embodiment is characterized in that smoothing means 3 for smoothing the pulsating voltage V1 is connected in parallel immediately before the second series circuit 11 of the light emitting unit 1. Note that the second series circuit 11 of the present embodiment has the same configuration as the first series circuit 10. That is, each of the first series circuit 10 and the second series circuit 11 is formed by connecting a resistor R and a plurality (n in this embodiment) of light emitting diodes L1 and L2 in series.

  The smoothing means 3 includes a diode D and a smoothing capacitor C, smoothes the pulsating voltage V1 input to the smoothing means 3, and outputs the smoothed smoothed voltage V2 to the second series circuit 11. The capacity of the smoothing capacitor C is such that the lower limit value of the smoothing voltage V2 exceeds the forward voltage n × Vf necessary for lighting the light emitting diode L2 of the second series circuit 11.

  The operation of this embodiment will be described below. As shown in FIG. 2B, the light emitting diode L1 of the first series circuit 10 is lit only when the pulsating voltage V1 exceeds the forward voltage n × Vf necessary for lighting the light emitting diode L1. Therefore, similarly to the first embodiment, the lighting state and the non-lighting state are alternately repeated. On the other hand, the light emitting diode L2 of the second series circuit 11 is always lit because the smoothed voltage V2 output from the smoothing means 3 is always higher than the forward voltage n × Vf required to light the light emitting diode L2. To do.

  As described above, since the light emitting diode L2 of the second series circuit 11 does not have a non-lighting period, for example, when the traffic signal is photographed with a video camera using the present embodiment as a traffic signal, the first series Even if the light emitting diode L1 of the circuit 10 is not lit, since the light emitting diode L2 of the second series circuit 11 is always lit, the lighting state of the light emitting diode L2 can be changed regardless of the shooting interval and timing of the video camera. Can be recognized.

  Further, since the smoothing means 3 is connected to the second series circuit 11 only and not to the entire circuit, the input current Iin to the light emitting unit 1 is maintained at a high power factor with almost no influence of the load current I2. be able to. Further, since the present embodiment does not smooth the entire light emitting unit 1, the capacity of the smoothing capacitor C used in the smoothing means 3 may be small. For example, a small capacitor such as a ceramic capacitor and having little influence on the life may be used. Can be used.

  In the present embodiment, the number of the second series circuit 11 to which the smoothing means 3 is connected is only one, but the number of circuits is not necessarily limited to one, and is within a range where the above effect can be obtained. A plurality of second series circuits 11 may be provided as long as they are present.

  In the first and second embodiments, the resistor R is used as the current limiting element. However, the resistor R is not necessarily limited to this, and a constant current circuit including a transistor, a shunt regulator, or the like instead of the resistor R. May be used.

(Embodiment 3)
Hereinafter, Embodiment 3 of the present invention will be described with reference to the drawings. In the present embodiment, as shown in FIG. 3C, the light emitting unit 1 and the lighting device 2 of the first embodiment are housed in a lamp 4 for a traffic signal. The lamp 4 is a substantially oval box having three substantially circular openings 40 for allowing the light emitting part 1 to face the outside, and the light emitting part 1 emits light over the entire surface of each opening 40. Diodes L1 and L2 are arranged to face each other.

  The colors emitted by the light emitting diodes L1 and L2 are different for each opening 40, and are green, yellow, and red in order from the left opening 40 in FIG. Needless to say, the colors emitted from the light emitting diodes L1 and L2 and the arrangement thereof are not limited to those described above, and can be changed according to the application of the traffic signal.

  In each opening 40, the light-emitting diode L2 of the second series circuit 11 is arranged at substantially the center, and the light-emitting diode L1 of the first series circuit 10 is arranged around it. Since the light emitting diode L2 of the second series circuit 10 has almost no non-lighting period, the light emitting diode L2 at the substantially center of each opening 40 is lighted almost constantly.

  Therefore, for example, when the moment of an accident is shot with a video camera of a drive recorder, the light-emitting diode L2 at the substantially center of each opening 40 is lit almost always, so the traffic signal state is independent of the shooting interval and timing of the video camera. Can be recognized.

  The light emitting unit 1 and the lighting device 2 according to the second embodiment may be housed in the lamp 4. In this case, as shown in FIG. 3A, it is desirable that the light emitting diode L <b> 2 of the second series circuit 11 is disposed at substantially the center of the opening 40. Arranging in this way facilitates circuit wiring. Further, as shown in FIG. 3B, the light emitting diode L <b> 2 of the second series circuit 11 may be disposed on the periphery of the opening 40. When arranged in this manner, it is possible to prevent an extreme difference from occurring in luminance variations due to the presence or absence of a non-lighting period between the light emitting diode L1 and the light emitting diode L2.

It is a figure which shows the light-emitting device of Embodiment 1 of this invention, (a) is a circuit diagram, (b) is a wave form diagram. It is a figure which shows the light-emitting device of Embodiment 2 of this invention, (a) is a circuit diagram, (b) is a wave form diagram. It is a figure which shows the light-emitting device of Embodiment 3 of this invention, (a) is a figure which shows the example of arrangement | positioning of a light emitting diode, (b) is a figure which shows the other example of arrangement | positioning of a light emitting diode, (c) is a whole figure. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission part 10 1st series circuit 11 2nd series circuit 2 Lighting device L1 1st light emitting diode (solid-state light emitting element)
L2 Second light emitting diode (solid state light emitting device)
R resistance (current limiting element)

Claims (8)

  A light emitting unit comprising a plurality of series circuits in which a current limiting element and a plurality of solid state light emitting devices are connected in series, and a driving voltage applied to the light emitting unit by full-wave rectification of an AC voltage connected to an AC power source. A light emitting device including a lighting device to supply, wherein the light emitting unit has a non-lighting period of at least one solid-state light emitting element of the series circuit shorter than a non-lighting period of the solid light-emitting element of another series circuit. A light emitting device.   2. The light emitting device according to claim 1, wherein the number of solid light emitting elements in at least one series circuit is smaller than the number of solid light emitting elements in another series circuit.   The light emitting device according to claim 2, wherein the light emitting unit includes one solid light emitting element in at least one series circuit.   The light emitting device according to claim 1, wherein the light emitting unit is connected to a smoothing unit in which at least one series circuit smoothes and outputs a driving voltage supplied from the lighting device.   5. The light emitting device according to claim 1, comprising the light emitting unit, the lighting device, and a lamp in which the light emitting unit and the lighting device are housed.   6. The light emitting device according to claim 5, wherein the lamp has an opening for making the light emitting portion face the outside, and a solid-state light emitting element of a series circuit having a short non-lighting period is arranged at substantially the center of the opening. apparatus.   6. The light-emitting device according to claim 5, wherein the lamp has an opening for allowing the light-emitting portion to face outside, and a solid-state light-emitting element of a series circuit having a short non-lighting period is disposed on the periphery of the opening. .   The light-emitting device according to claim 5, wherein the light-emitting unit, the lighting device, and the lamp are for traffic signals.

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