JP2023175424A - Lightning circuit for vehicle lightning tool, and lightning tool for vehicle including the same - Google Patents

Lightning circuit for vehicle lightning tool, and lightning tool for vehicle including the same Download PDF

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JP2023175424A
JP2023175424A JP2022087856A JP2022087856A JP2023175424A JP 2023175424 A JP2023175424 A JP 2023175424A JP 2022087856 A JP2022087856 A JP 2022087856A JP 2022087856 A JP2022087856 A JP 2022087856A JP 2023175424 A JP2023175424 A JP 2023175424A
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circuit
voltage
semiconductor light
light emitting
terminal
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誠之 久米田
Masayuki Kumeta
スフィ ニック
Nik Sufi
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Ichikoh Industries Ltd
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Ichikoh Industries Ltd
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Priority to PCT/JP2023/019723 priority patent/WO2023234210A1/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/40—Details of LED load circuits
    • H05B45/44—Details of LED load circuits with an active control inside an LED matrix
    • H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices

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  • Circuit Arrangement For Electric Light Sources In General (AREA)
  • Lighting Device Outwards From Vehicle And Optical Signal (AREA)

Abstract

To solve the problem that the brightness of a lightning tool may be rapidly increased when increasing the number of lightings of a light source in the lightning tool in the conventional art.SOLUTION: A lightning circuit 1 contains: a bypass circuit 31 connected in parallel to one LED3 contained in an LED string 11 to which three LED1 to LED3 are serially connected; and a voltage dividing circuit 41 that resistively divides an input voltage Vin and generates a divided voltage Vdiv. The bypass circuit 31 contains a transistor Q3. The transistor Q3 includes: a drain terminal connected to an anode terminal of the LED3; a source terminal connected to a cathode terminal of the LED3; and a gate terminal to which the divided voltage Vdiv is supplied.SELECTED DRAWING: Figure 1

Description

本開示は、車両灯具用の点灯回路及びこれを含む車両用灯具に関する。 The present disclosure relates to a lighting circuit for a vehicle lamp and a vehicle lamp including the same.

車両に搭載される電源は、商用電源から独立した独立電源であるため、気温といった環境変化又は長期間の使用によってその出力電圧が低下してしまうことがある。このような問題を回避するため特許文献１の背景技術において説明されているように、ＬＥＤ直列回路（以下、ＬＥＤストリングと呼ぶ）に含まれる所定ＬＥＤに対してバイパス回路を並列に接続し、電源出力の低下時にバイパス回路をオンさせてＬＥＤストリングにおける他のＬＥＤの点灯を確保することが行われている。特許文献２にもＬＥＤストリングに含まれる特定のＬＥＤにバイパス回路を並列に接続することが開示されている。 Since the power supply installed in a vehicle is an independent power supply independent of a commercial power supply, its output voltage may decrease due to environmental changes such as temperature or long-term use. In order to avoid such problems, as explained in the background art of Patent Document 1, a bypass circuit is connected in parallel to a predetermined LED included in an LED series circuit (hereinafter referred to as an LED string), and the power source is When the output decreases, a bypass circuit is turned on to ensure lighting of other LEDs in the LED string. Patent Document 2 also discloses connecting a bypass circuit in parallel to specific LEDs included in an LED string.

特開２０２０－９５８１６号公報JP2020-95816A 国際公開第２０２０／０４５２７１号International Publication No. 2020/045271

電源出力が低電圧状態から（それよりも高い）高電圧状態に復帰する時、ＬＥＤストリングに含まれる特定ＬＥＤに並列接続されたバイパス回路に流れる電流を遮断するためにそのバイパス回路に含まれるスイッチをオンからオフに切り替えることになる。本願発明者の検討によると、このスイッチのオンからオフへの切換時、特定ＬＥＤが急に点灯を開始し、周囲から見て灯具の明るさが急増してしまう（所謂、ちらつきが生じてしまう）おそれがある。 A switch included in the bypass circuit to cut off the current flowing through the bypass circuit connected in parallel to a specific LED included in the LED string when the power supply output returns from a low voltage state to a high voltage state (higher than that). will be switched from on to off. According to the inventor's study, when this switch is switched from on to off, a specific LED suddenly starts lighting up, and the brightness of the lamp increases rapidly when viewed from the surroundings (so-called flickering occurs). ) There is a risk.

本開示の一態様に係る車両灯具用の点灯回路は、Ｍ（Ｍは２以上の自然数を示す）個の半導体発光素子が直列に接続された半導体発光素子の直列回路に含まれるＭ－１以下の個数の半導体発光素子に対して並列に接続されたバイパス回路と、入力電圧を抵抗分圧して分圧電圧を生成する分圧回路を含む。バイパス回路は、少なくとも一つの電界効果トランジスタを含む。少なくとも一つの電界効果トランジスタは、Ｍ－１以下の個数の半導体発光素子のアノード端子に接続されたドレイン端子、Ｍ－１以下の個数の半導体発光素子のカソード端子に接続されたソース端子、及び分圧電圧が供給されるゲート端子を有する。 A lighting circuit for a vehicle lamp according to one aspect of the present disclosure includes M-1 or less semiconductor light-emitting elements included in a series circuit of semiconductor light-emitting elements in which M (M represents a natural number of 2 or more) semiconductor light-emitting elements are connected in series. The circuit includes a bypass circuit connected in parallel to the number of semiconductor light emitting elements, and a voltage dividing circuit that divides an input voltage with resistance to generate a divided voltage. The bypass circuit includes at least one field effect transistor. The at least one field effect transistor has a drain terminal connected to an anode terminal of M-1 or less semiconductor light-emitting devices, a source terminal connected to a cathode terminal of M-1 or less semiconductor light-emitting devices, and a drain terminal connected to anode terminals of M-1 or less semiconductor light-emitting devices. It has a gate terminal to which a piezoelectric voltage is supplied.

幾つかの実施形態においては、点灯回路は、半導体発光素子の直列回路に直列に接続された定電流回路を更に含む。 In some embodiments, the lighting circuit further includes a constant current circuit connected in series to the series circuit of semiconductor light emitting devices.

幾つかの実施形態においては、点灯回路は、入力電圧が閾値電圧を超える時、少なくとも一つの電界効果トランジスタのゲート端子をグランドに接続する放電回路を更に含む。放電回路は、少なくとも一つの電界効果トランジスタのゲート端子をグランド電位に接続する放電スイッチと、入力電圧を抵抗分圧して分圧電圧を生成して放電スイッチに供給する分圧回路を含み得る。 In some embodiments, the lighting circuit further includes a discharge circuit that connects the gate terminal of the at least one field effect transistor to ground when the input voltage exceeds a threshold voltage. The discharge circuit may include a discharge switch that connects the gate terminal of at least one field effect transistor to a ground potential, and a voltage divider circuit that divides an input voltage with a resistor to generate a divided voltage and supplies the divided voltage to the discharge switch.

幾つかの実施形態においては、点灯回路は、少なくとも一つの電界効果トランジスタのゲート端子を保護する保護回路を更に含む。保護回路は、少なくとも一つのツェナーダイオードを含み得る。 In some embodiments, the lighting circuit further includes a protection circuit that protects the gate terminal of the at least one field effect transistor. The protection circuit may include at least one Zener diode.

幾つかの実施形態においては、少なくとも一つの電界効果トランジスタがＮチャンネル電界効果トランジスタである。 In some embodiments, at least one field effect transistor is an N-channel field effect transistor.

幾つかの実施形態においては、Ｍ個が３個を示し、Ｍ－１以下の個数が１個を示す。 In some embodiments, M represents three, and M-1 or less represents one.

本開示の別態様に係る車両灯具用の点灯回路は、Ｍ（Ｍは２以上の自然数を示す）個の半導体発光素子が直列に接続された半導体発光素子の直列回路に含まれるＭ－１以下の個数の半導体発光素子に対して並列に接続されたバイパス回路がターンオフするターンオフ電圧に向けて入力電圧が増加する時、バイパス回路に流れるバイパス電流が漸減し、かつＭ－１以下の個数の半導体発光素子に流れる駆動電流が漸増するように構成される。点灯回路は、入力電圧を抵抗分圧してバイパス回路に分圧電圧を供給する分圧回路を含み得る。上述様々な特徴が、本段落で述べた点灯回路にも同様に適用可能である。 A lighting circuit for a vehicle lamp according to another aspect of the present disclosure includes M-1 or less semiconductor light-emitting elements included in a series circuit of semiconductor light-emitting elements in which M (M represents a natural number of 2 or more) semiconductor light-emitting elements are connected in series. When the input voltage increases toward the turn-off voltage at which the bypass circuit connected in parallel to the number of semiconductor light emitting devices is turned off, the bypass current flowing through the bypass circuit gradually decreases, and The driving current flowing through the light emitting element is configured to gradually increase. The lighting circuit may include a voltage divider circuit that divides the input voltage with resistance and supplies the divided voltage to the bypass circuit. The various features described above are equally applicable to the lighting circuit described in this paragraph.

本開示の一態様によれば、灯具における光源の点灯数を増加する時、灯具の明るさが急増してしまうこと（所謂、ちらつきが生じてしまうこと）が抑制される。 According to one aspect of the present disclosure, when the number of light sources in a lamp is increased, a sudden increase in the brightness of the lamp (so-called flickering) is suppressed.

本開示の一態様に係る点灯回路の概略的な回路図である。FIG. 2 is a schematic circuit diagram of a lighting circuit according to one aspect of the present disclosure. 図１に示した点灯回路のバイパス回路の電界効果トランジスタのゲート端子電圧とドレイン端子電圧の関係を示すグラフである。2 is a graph showing the relationship between the gate terminal voltage and drain terminal voltage of the field effect transistor of the bypass circuit of the lighting circuit shown in FIG. 1. FIG. 入力電圧と光束（単位：ルーメン）の関係を示すグラフである。It is a graph showing the relationship between input voltage and luminous flux (unit: lumen). 本開示の別態様に係る点灯回路の概略的な回路図である。FIG. 3 is a schematic circuit diagram of a lighting circuit according to another aspect of the present disclosure. 図４に示した点灯回路のバイパス回路の電界効果トランジスタのゲート端子電圧がグランド電位まで落とされることを示すグラフである。5 is a graph showing that the gate terminal voltage of the field effect transistor of the bypass circuit of the lighting circuit shown in FIG. 4 is lowered to the ground potential. 本開示のまた別態様に係る点灯回路の概略的な回路図である。FIG. 7 is a schematic circuit diagram of a lighting circuit according to another aspect of the present disclosure.

以下、図面を参照しつつ、本発明の非限定の実施形態及び特徴について説明する。当業者は、過剰説明を要せず、各実施形態及び／又は各特徴を組み合わせることができ、この組み合わせによる相乗効果も理解可能である。実施形態間の重複説明は、原則的に省略する。参照図面は、発明の記述を主たる目的とするものであり、作図の便宜のために簡略化されている。各特徴は、本明細書に開示された駆動回路にのみ有効であるものではなく、本明細書に開示されていない他の様々な駆動回路にも通用する普遍的な特徴として理解される。 Hereinafter, non-limiting embodiments and features of the present invention will be described with reference to the drawings. Those skilled in the art can combine each embodiment and/or each feature without needing excessive explanation, and can also understand the synergistic effect of this combination. Duplicate explanations between embodiments will be omitted in principle. The reference drawings are primarily for the purpose of describing the invention and are simplified for ease of drawing. Each feature is understood as a universal feature that is not only valid for the drive circuit disclosed in this specification, but also applies to various other drive circuits not disclosed in this specification.

図１乃至図３を参照して説明する。図１は、点灯回路１の概略的な回路図である。図２は、図１に示した点灯回路１のバイパス回路３１のトランジスタＱ３のゲート端子電圧とドレイン端子電圧の関係を示すグラフである。図３は、入力電圧Ｖinと光束（単位：ルーメン）の関係を示すグラフである。 This will be explained with reference to FIGS. 1 to 3. FIG. 1 is a schematic circuit diagram of a lighting circuit 1. As shown in FIG. FIG. 2 is a graph showing the relationship between the gate terminal voltage and drain terminal voltage of the transistor Q3 of the bypass circuit 31 of the lighting circuit 1 shown in FIG. FIG. 3 is a graph showing the relationship between input voltage V in and luminous flux (unit: lumen).

点灯回路１は、車両灯具用の点灯回路であり、典型的には、ターンランプの点灯のために用いられる（勿論、他の種類の灯具の点灯のために用いることもできる）。図示例では、点灯回路１は、３個のＬＥＤ1～ＬＥＤ3が直列に接続されたＬＥＤストリング（半導体発光素子の直列回路）１１のための点灯回路である（図１参照）。当然ながら、ＬＥＤストリング１１に含まれるＬＥＤの個数は、Ｍ（Ｍは２以上の自然数を示す）個以上であれば良く、３個に限られるべきではない。バイパス回路３１が並列接続するＬＥＤの個数もＭ－１以下であれば良く、１個に限られるべきではない。ＬＥＤ以外のＬＤ（Laser diode）といった他の種類の半導体発光素子も採用可能である。 The lighting circuit 1 is a lighting circuit for a vehicle lamp, and is typically used for lighting a turn lamp (of course, it can also be used for lighting other types of lamps). In the illustrated example, the lighting circuit 1 is a lighting circuit for an LED string (series circuit of semiconductor light emitting elements) 11 in which three LEDs 1 to LED 3 are connected in series (see FIG. 1). Naturally, the number of LEDs included in the LED string 11 may be M (M represents a natural number of 2 or more) or more, and should not be limited to three. The number of LEDs connected in parallel by the bypass circuit 31 may also be less than or equal to M-1, and should not be limited to one. Other types of semiconductor light emitting elements such as LDs (Laser diodes) other than LEDs can also be used.

点灯回路１は、車両に搭載された独立電源（ＤＣ電源）に接続される。点灯回路１の第１電源端子１ａと第２電源端子１ｂの間に独立電源から供給された入力電圧Ｖinが印加される。入力電圧Ｖinが大きく低下すると３個のＬＥＤ1～ＬＥＤ3の全消灯してしまうおそれがある。入力電圧Ｖinの低下時、３個のＬＥＤ1～ＬＥＤ3のうち一つのＬＥＤ3を選択的に消灯することで全消灯が回避可能である。なお、入力電圧Ｖinは、２値信号のパルス信号として点灯回路１に供給され得る。パルス信号が第１レベル（例えば、高電位レベル）の時に３灯のＬＥＤ1～ＬＥＤ3が点灯し、パルス信号が第２レベル（例えば、低電位レベル）の時に３灯のＬＥＤ1～ＬＥＤ3が消灯する。ＬＥＤ3が選択的に消灯する場合、パルス信号が第１レベルの時に２灯のＬＥＤ1，ＬＥＤ2が点灯し、パルス信号が第２レベルの時に２灯のＬＥＤ1，ＬＥＤ2が消灯する。 The lighting circuit 1 is connected to an independent power source (DC power source) mounted on a vehicle. An input voltage V in supplied from an independent power supply is applied between the first power supply terminal 1 a and the second power supply terminal 1 b of the lighting circuit 1 . If the input voltage V in decreases significantly, there is a risk that all three LEDs 1 to 3 will be turned off. When the input voltage V in decreases, all lights out can be avoided by selectively turning off one LED 3 among the three LEDs 1 to LED 3 . Note that the input voltage V in can be supplied to the lighting circuit 1 as a binary pulse signal. When the pulse signal is at the first level (for example, high potential level), the three lights LED 1 to LED 3 light up, and when the pulse signal is at the second level (for example, low potential level), the three lights LED 1 to LED 3 light up. goes out. When the LED 3 is selectively turned off, the two LEDs 1 and 2 are turned on when the pulse signal is at the first level, and the two LEDs 1 and 2 are turned off when the pulse signal is at the second level.

なお、ＬＥＤストリング１１（例えば、そのアノード端子）は、点灯回路１の第１電源線１ｐを介して第１電源端子１ａに接続される。ＬＥＤストリング１１（例えば、そのカソード端子）は、点灯回路１の第２電源線１ｑを介して第２電源端子１ｂに接続される。 Note that the LED string 11 (for example, its anode terminal) is connected to the first power supply terminal 1a via the first power supply line 1p of the lighting circuit 1. The LED string 11 (for example, its cathode terminal) is connected to the second power supply terminal 1b via the second power supply line 1q of the lighting circuit 1.

より具体的には、点灯回路１は、ＬＥＤストリング１１に直列に接続された定電流回路２１と、ＬＥＤストリング１１に含まれる１個のＬＥＤ3に対して並列に接続されたバイパス回路３１と、入力電圧Ｖinを抵抗分圧して分圧電圧Ｖdivを生成する分圧回路４１を含む。図１では、点灯回路１にＬＥＤストリング１１が含まれていないが、それを含むように再定義することも可能である。 More specifically, the lighting circuit 1 includes a constant current circuit 21 connected in series to the LED string 11, a bypass circuit 31 connected in parallel to one LED 3 included in the LED string 11, It includes a voltage dividing circuit 41 that divides the input voltage V in with resistance to generate a divided voltage V div . In FIG. 1, the lighting circuit 1 does not include the LED string 11, but it can be redefined to include it.

定電流回路２１は、入力電圧Ｖinに応じてＬＥＤストリング１１に一定の駆動電流Ｉdを流すように構成及び接続される。電源に対して、ＬＥＤストリング１１と定電流回路２１の直列回路が並列に接続される。定電流回路２１を如何なる回路素子を用いて如何に構成するかは当業者が行う通常の設計の範疇にある。従って、その詳細な説明は省略する。 The constant current circuit 21 is configured and connected so as to cause a constant drive current I d to flow through the LED string 11 according to the input voltage Vin . A series circuit of an LED string 11 and a constant current circuit 21 is connected in parallel to a power source. How to configure the constant current circuit 21 using what kind of circuit elements is within the scope of ordinary design performed by those skilled in the art. Therefore, detailed explanation thereof will be omitted.

バイパス回路３１は、ＬＥＤストリング１１に含まれる１個のＬＥＤ3を選択的に消灯するように構成及び接続される。バイパス回路３１のオフ時、ＬＥＤ1とＬＥＤ2に流れた駆動電流Ｉdの全てがＬＥＤ3に流れる。バイパス回路３１のオン時、駆動電流Ｉdは、ＬＥＤ３とバイパス回路３１の間で分流され、ＬＥＤ3に駆動電流Ｉd1が流れ、バイパス回路３１にバイパス電流Ｉd2が流れる（ここでは、ＬＥＤ3に流れる駆動電流Ｉd1は、ＬＥＤ1とＬＥＤ2に流れる駆動電流Ｉdよりも小さい）。バイパス回路３１は、バイパス回路３１がオンからオフになる時（即ち、入力電圧Ｖinがバイパス回路３１のターンオフ電圧Ｖoffに向けて増加する時）、後述のようにバイパス回路３１に流れるバイパス電流Ｉd2が漸減し、ＬＥＤ3に流れる駆動電流Ｉd1が漸増するように構成される。これによりＬＥＤの点灯数が増加する時、灯具（例えば、ターンランプ）の明るさが急増してしまうことが抑制される。 The bypass circuit 31 is configured and connected to selectively turn off one LED 3 included in the LED string 11. When the bypass circuit 31 is off, all of the drive current I d that has flowed through LED 1 and LED 2 flows through LED 3 . When the bypass circuit 31 is on, the drive current I d is divided between the LED 3 and the bypass circuit 31, the drive current I d1 flows through the LED 3 , and the bypass current I d2 flows through the bypass circuit 31 (here, the LED 3 The drive current I d1 flowing through LED 1 and LED 2 is smaller than the drive current I d flowing through LED 1 and LED 2). The bypass circuit 31 has a bypass current flowing through the bypass circuit 31 as described below when the bypass circuit 31 is turned from on to off (that is, when the input voltage V in increases toward the turn-off voltage V off of the bypass circuit 31 ). It is configured such that I d2 gradually decreases and the drive current I d1 flowing through the LED 3 gradually increases. This prevents the brightness of the lamp (for example, turn lamp) from increasing rapidly when the number of LEDs lit increases.

分圧回路４１は、入力電圧Ｖinを抵抗分圧して分圧電圧Ｖdivを生成し、これをバイパス回路３１に供給する。詳細には、分圧回路４１は、直列接続された抵抗器Ｒ６と抵抗器Ｒ７を含み、これらのノードＮ6において分圧電圧Ｖdivが生じる。後述の説明から分かるように、分圧電圧Ｖdivは、バイパス回路３１に流れるバイパス電流Ｉd2（即ち、単位時間当たりに流れる電荷量）に関連し、端的には、それを決定付ける一要素である。尚、ノードＮ6と第１電源線１ｐの間に接続される抵抗器の数は一つに限られるべきではなく、ノードＮ6と第２電源線１ｑの間に接続される抵抗器の数についても同様である。当然ながら、分圧電圧Ｖdivは、入力電圧Ｖinに比例する。従って、入力電圧Ｖinに比例する分圧電圧Ｖdivが後述のバイパス回路３１のトランジスタＱ３のゲート端子に供給される。 The voltage dividing circuit 41 divides the input voltage V in with resistance to generate a divided voltage V div and supplies this to the bypass circuit 31 . Specifically, the voltage dividing circuit 41 includes a resistor R6 and a resistor R7 connected in series, and a divided voltage V div is generated at a node N 6 of these resistors R6 and R7. As can be seen from the explanation below, the divided voltage V div is related to the bypass current I d2 (that is, the amount of charge flowing per unit time) flowing through the bypass circuit 31, and is simply one of the factors that determines it. be. Note that the number of resistors connected between the node N 6 and the first power line 1p should not be limited to one, but the number of resistors connected between the node N 6 and the second power line 1q. The same applies to Naturally, the divided voltage V div is proportional to the input voltage Vin . Therefore, a divided voltage V div proportional to the input voltage V in is supplied to the gate terminal of the transistor Q3 of the bypass circuit 31, which will be described later.

バイパス回路３１は、ＬＥＤストリング１１に含まれるＬＥＤ3に対して並列接続された少なくとも一つのトランジスタＱ３を含む。トランジスタＱ３は、電界効果トランジスタ（ＭＯＳＦＥＴ（metal-oxide-semiconductor field-effect transistor））であり、典型的には、Ｎチャンネル電界効果トランジスタである。トランジスタＱ３のドレイン端子が、ＬＥＤ3のアノード端子に接続される。トランジスタＱ３のソース端子が、ＬＥＤ3のカソード端子に接続される。トランジスタＱ３のゲート端子が分圧回路４１に接続されて分圧回路４１から分圧電圧Ｖdivが供給される。本構成を採用することにより灯具（例えば、ターンランプ）におけるＬＥＤの点灯数が増加する時、灯具の明るさが急増してしまうことが抑制される。トランジスタＱ３のゲート端子は、分圧回路４１において分圧電圧Ｖdivが生成されるノード（例えば、分圧回路４１の抵抗器Ｒ６と抵抗器Ｒ７の間のノードＮ6）に接続される。 Bypass circuit 31 includes at least one transistor Q3 connected in parallel to LED 3 included in LED string 11. Transistor Q3 is a field-effect transistor (MOSFET), typically an N-channel field-effect transistor. The drain terminal of transistor Q3 is connected to the anode terminal of LED 3 . The source terminal of transistor Q3 is connected to the cathode terminal of LED 3 . The gate terminal of the transistor Q3 is connected to the voltage dividing circuit 41, and the divided voltage V div is supplied from the voltage dividing circuit 41. By employing this configuration, when the number of LEDs lit in a lamp (for example, a turn lamp) increases, the brightness of the lamp can be prevented from increasing rapidly. The gate terminal of the transistor Q3 is connected to a node where the divided voltage V div is generated in the voltage dividing circuit 41 (for example, a node N 6 between the resistor R6 and the resistor R7 of the voltage dividing circuit 41).

図２に示すように、トランジスタＱ３のターンオフ電圧Ｖoffは、トランジスタＱ３のドレイン端子電圧Ｖdがゲート端子電圧Ｖgを超える時である。トランジスタＱ３のドレイン端子電圧Ｖdがゲート端子電圧Ｖg未満のトランジスタＱ３のオン領域では、トランジスタＱ３に流れる電流は、トランジスタＱ３のドレイン端子電位とゲート端子電位の電位差に比例する。従って、入力電圧Ｖinがターンオフ電圧Ｖoffに向けて増加する時（図２の矢印Ｄ１参照）、トランジスタＱ３のドレイン－ゲート電圧Ｖdgが漸減し、トランジスタＱ３（バイパス回路３１）に流れるバイパス電流Ｉd2が漸減する。バイパス電流Ｉd2の漸減に反比例してＬＥＤ3に流れる駆動電流Ｉd1が漸増する。このようにして灯具（例えば、ターンランプ）におけるＬＥＤの点灯数が増加する時（図例では、２灯から３灯に点灯数が増加する時）、灯具の明るさが急増してしまうことが抑制される（図３の実線と一点鎖線を比較のこと）。 As shown in FIG. 2, the turn- off voltage Voff of the transistor Q3 is when the drain terminal voltage Vd of the transistor Q3 exceeds the gate terminal voltage Vg . In the on region of the transistor Q3 where the drain terminal voltage V d of the transistor Q3 is less than the gate terminal voltage V g , the current flowing through the transistor Q3 is proportional to the potential difference between the drain terminal potential and the gate terminal potential of the transistor Q3. Therefore, when the input voltage V in increases toward the turn-off voltage V off (see arrow D1 in FIG. 2), the drain-gate voltage V dg of the transistor Q3 gradually decreases, and the bypass current flows through the transistor Q3 (bypass circuit 31). I d2 gradually decreases. The drive current I d1 flowing through the LED 3 gradually increases in inverse proportion to the gradual decrease of the bypass current I d2 . In this way, when the number of LEDs lit in a light fixture (for example, a turn lamp) increases (in the example, when the number of lighted LEDs increases from 2 to 3 lights), the brightness of the light fixture will increase rapidly. (Compare the solid line and the dashed-dotted line in FIG. 3).

図２に示すように、トランジスタＱ３のゲート端子電圧Ｖgとドレイン端子電圧Ｖdは、入力電圧Ｖinの変化に応じて異なる電圧変化線を描く。ゲート端子電圧Ｖgは、（上述のように分圧回路４１から分圧電圧Ｖdivが供給されるため）入力電圧Ｖinに正比例して変化し、その電圧変化線が直線の傾斜線になる。ドレイン端子電圧Ｖdは、定電流回路２１が入力電圧Ｖinの変化に関わらずに一定の駆動電流Ｉdを流すように機能するため入力電圧Ｖinに正比例しない範囲を持ち、更には、その範囲外においてゲート端子電圧Ｖgの電圧変化線とは異なる（それよりも大きい）傾きの電圧変化線を描く。なお、トランジスタＱ３のターンオフ電圧Ｖoffは、ゲート端子電圧Ｖgの電圧変化線とドレイン端子電圧Ｖdの電圧変化線の交点に設定される。 As shown in FIG. 2, the gate terminal voltage V g and drain terminal voltage V d of the transistor Q3 draw different voltage change lines according to changes in the input voltage V in . The gate terminal voltage V g changes in direct proportion to the input voltage V in (because the divided voltage V div is supplied from the voltage dividing circuit 41 as described above), and the voltage change line becomes a straight slope line. . The drain terminal voltage V d has a range that is not directly proportional to the input voltage V in because the constant current circuit 21 functions to flow a constant drive current I d regardless of changes in the input voltage V in ; Outside the range, a voltage change line with a slope different from (greater than) the voltage change line of the gate terminal voltage V g is drawn. Note that the turn- off voltage Voff of the transistor Q3 is set at the intersection of the voltage change line of the gate terminal voltage Vg and the voltage change line of the drain terminal voltage Vd .

図４及び図５を参照して更に説明する。図４は、本開示の別態様に係る点灯回路１の概略的な回路図である。図５は、図４に示した点灯回路１のバイパス回路３１のトランジスタＱ３のゲート端子電圧がグランド電位まで落とされることを示すグラフである。 This will be further explained with reference to FIGS. 4 and 5. FIG. 4 is a schematic circuit diagram of a lighting circuit 1 according to another aspect of the present disclosure. FIG. 5 is a graph showing that the gate terminal voltage of the transistor Q3 of the bypass circuit 31 of the lighting circuit 1 shown in FIG. 4 is lowered to the ground potential.

点灯回路１は、入力電圧Ｖinが閾値電圧Ｖthを超える時、トランジスタＱ３のゲート端子をグランドに接続する放電回路４２を含むことができる（図４参照）。放電回路４２は、抵抗器Ｒ１６，Ｒ１７、及び放電スイッチＱ４を含む。抵抗器Ｒ１６，Ｒ１７から分圧回路が生成され、これが、入力電圧Ｖinを抵抗分圧して分圧電圧を生成し、放電スイッチＱ４の制御端子に供給（印加）する。放電スイッチＱ４は、典型的には、バイポーラトランジスタ又は電界効果トランジスタといった３端子スイッチである。放電スイッチＱ４の第１端子（例えば、ドレイン端子）は、トランジスタＱ３のゲート端子に接続される。放電スイッチＱ４の第２端子（例えば、ソース端子）は、グランド電位に接続される。放電スイッチＱ４の制御端子（例えば、ゲート端子）は、抵抗器Ｒ１６，Ｒ１７間のノードＮ7に接続される。 The lighting circuit 1 can include a discharge circuit 42 that connects the gate terminal of the transistor Q3 to ground when the input voltage V in exceeds the threshold voltage V th (see FIG. 4). Discharge circuit 42 includes resistors R16, R17 and discharge switch Q4. A voltage divider circuit is generated from the resistors R16 and R17, which divides the input voltage V in to generate a divided voltage, and supplies (applies) the divided voltage to the control terminal of the discharge switch Q4. Discharge switch Q4 is typically a three terminal switch such as a bipolar transistor or a field effect transistor. A first terminal (eg, a drain terminal) of discharge switch Q4 is connected to a gate terminal of transistor Q3. A second terminal (for example, a source terminal) of the discharge switch Q4 is connected to the ground potential. A control terminal (eg, gate terminal) of discharge switch Q4 is connected to node N7 between resistors R16 and R17.

図５に示すように入力電圧Ｖinが閾値電圧Ｖthを超える時、放電スイッチＱ４がオンしてトランジスタＱ３のゲート端子がグランドに接続される。放電スイッチＱ４が完全にオンする時、トランジスタＱ３のゲート端子がグランド電位まで低下し、トランジスタＱ３がオンする可能性がなくなる。トランジスタＱ３がオンしないことはバイパス回路３１がオンしないことを意味する。従って、ＬＥＤ3が故障するとしてもバイパス回路３１がオンしてＬＥＤ1とＬＥＤ2が点灯を継続することが回避される。 As shown in FIG. 5, when the input voltage V in exceeds the threshold voltage V th , the discharge switch Q4 is turned on and the gate terminal of the transistor Q3 is connected to ground. When the discharge switch Q4 is completely turned on, the gate terminal of the transistor Q3 drops to the ground potential, and there is no possibility that the transistor Q3 will turn on. The fact that the transistor Q3 is not turned on means that the bypass circuit 31 is not turned on. Therefore, even if LED 3 fails, it is avoided that the bypass circuit 31 is turned on and LED 1 and LED 2 continue to light up.

図６を参照して更に説明する。図６は、本開示のまた別態様に係る点灯回路１の概略的な回路図である。点灯回路１は、図４に示した放電回路４２の追加又は代替として、トランジスタＱ３のゲート端子を保護する保護回路４３を含むことができる（図６参照）。保護回路４３は、ツェナーダイオードＺＤ２、抵抗器Ｒ８、及び抵抗器Ｒ９を含む。抵抗器Ｒ８及び抵抗器Ｒ９により分圧回路が形成される。抵抗器Ｒ８と抵抗器Ｒ９の間のノードＮ8がトランジスタＱ３のゲート端子に接続され、そこに分圧電圧が供給される。トランジスタＱ３を破壊するような高電圧が点灯回路１に印加される時、ツェナーダイオードＺＤ２がオンして電流がグランド側に電流を流す。抵抗器Ｒ８と抵抗器Ｒ９の間のノードＮ8に分圧電圧が生成されてトランジスタＱ３のゲート端子に供給される。従って、トランジスタＱ３のゲート端子に高電圧が印加することが回避でき、かつトランジスタＱ３のゲート端子がフローティング状態になることが回避される。 This will be further explained with reference to FIG. FIG. 6 is a schematic circuit diagram of a lighting circuit 1 according to another aspect of the present disclosure. The lighting circuit 1 can include a protection circuit 43 that protects the gate terminal of the transistor Q3 in addition to or in place of the discharge circuit 42 shown in FIG. 4 (see FIG. 6). The protection circuit 43 includes a Zener diode ZD2, a resistor R8, and a resistor R9. A voltage dividing circuit is formed by resistor R8 and resistor R9. A node N8 between resistor R8 and resistor R9 is connected to the gate terminal of transistor Q3, and a divided voltage is supplied thereto. When a high voltage that destroys the transistor Q3 is applied to the lighting circuit 1, the Zener diode ZD2 is turned on and current flows to the ground side. A divided voltage is generated at node N8 between resistor R8 and resistor R9 and is supplied to the gate terminal of transistor Q3. Therefore, it is possible to avoid applying a high voltage to the gate terminal of the transistor Q3, and to prevent the gate terminal of the transistor Q3 from being in a floating state.

繰り返すが、トランジスタＱ３が並列接続されるＬＥＤの個数（即ち、Ｍ－１以下の個数）は１個に限られない。トランジスタＱ３が、２個以上のＬＥＤが直列接続されたサブストリングに対して並列接続される時、トランジスタＱ３のドレイン端子は、そのサブストリングにおいて最も第１電源端子１ａ寄りに位置するＬＥＤのアノード端子に接続され、トランジスタＱ３のソース端子は、そのサブストリングにおいて最も第２電源端子１ｂ寄りに位置するＬＥＤのカソード端子に接続される。 To repeat, the number of LEDs to which the transistor Q3 is connected in parallel (ie, the number of LEDs equal to or less than M-1) is not limited to one. When the transistor Q3 is connected in parallel to a substring in which two or more LEDs are connected in series, the drain terminal of the transistor Q3 is the anode terminal of the LED located closest to the first power supply terminal 1a in the substring. The source terminal of the transistor Q3 is connected to the cathode terminal of the LED located closest to the second power supply terminal 1b in the substring.

上述の開示を踏まえ、当業者は、各実施形態及び各特徴に対して様々な変更を加えることができる。車両とは、四輪車に限らず、二輪車、三輪車等であっても良い。トランジスタＱ３は、ＮチャンネルＭＯＳＦＥＴとして説明したが、ＰチャンネルＭＯＳＦＥＴとすることもできる。後者の場合、他の回路素子についてＮ型とＰ型を反転して再設計することが必要になり得る。トランジスタＱ３と分圧回路４１以外の組み合わせにて上述の制御を実施することも可能であろう。点灯回路１に含まれるトランジスタＱ３と分圧回路４１をＬＥＤ3の点灯回路又はその点灯状態を切り替える切換回路と命名することもできる。 In light of the above disclosure, those skilled in the art can make various modifications to each embodiment and each feature. The vehicle is not limited to a four-wheeled vehicle, but may also be a two-wheeled vehicle, a three-wheeled vehicle, or the like. Although transistor Q3 has been described as an N-channel MOSFET, it can also be a P-channel MOSFET. In the latter case, it may be necessary to reverse the N-type and P-type and redesign other circuit elements. It would also be possible to implement the above-mentioned control using a combination other than the transistor Q3 and the voltage divider circuit 41. The transistor Q3 and the voltage dividing circuit 41 included in the lighting circuit 1 can also be named a lighting circuit for the LED 3 or a switching circuit for switching the lighting state of the LED 3.

１ ：点灯回路
１１ ：ＬＥＤストリング
２１ ：定電流回路
３１ ：バイパス回路
４１ ：分圧回路
４２ ：放電回路
４３ ：保護回路

Ｑ３ ：トランジスタ
Ｑ４ ：放電スイッチ 1: Lighting circuit 11: LED string 21: Constant current circuit 31: Bypass circuit 41: Voltage dividing circuit 42: Discharge circuit 43: Protection circuit

Q3: Transistor Q4: Discharge switch

Claims (12)

車両灯具用の点灯回路であって、
Ｍ（Ｍは２以上の自然数を示す）個の半導体発光素子が直列に接続された半導体発光素子の直列回路に含まれるＭ－１以下の個数の半導体発光素子に対して並列に接続されたバイパス回路と、
入力電圧を抵抗分圧して分圧電圧を生成する分圧回路を備え、
前記バイパス回路は、少なくとも一つの電界効果トランジスタを含み、
前記少なくとも一つの電界効果トランジスタは、前記Ｍ－１以下の個数の半導体発光素子のアノード端子に接続されたドレイン端子、前記Ｍ－１以下の個数の半導体発光素子のカソード端子に接続されたソース端子、及び前記分圧電圧が供給されるゲート端子を有する、点灯回路。 A lighting circuit for a vehicle lamp,
A bypass connected in parallel to M-1 or less semiconductor light emitting elements included in a series circuit of semiconductor light emitting elements in which M (M represents a natural number of 2 or more) semiconductor light emitting elements are connected in series. circuit and
Equipped with a voltage divider circuit that divides the input voltage with resistance to generate a divided voltage.
the bypass circuit includes at least one field effect transistor;
The at least one field effect transistor has a drain terminal connected to an anode terminal of the M-1 or less semiconductor light emitting devices, and a source terminal connected to a cathode terminal of the M-1 or less semiconductor light emitting devices. , and a gate terminal to which the divided voltage is supplied. 前記半導体発光素子の直列回路に直列に接続された定電流回路を更に備える、請求項１に記載の点灯回路。 The lighting circuit according to claim 1, further comprising a constant current circuit connected in series to the series circuit of the semiconductor light emitting elements. 前記入力電圧が閾値電圧を超える時、前記少なくとも一つの電界効果トランジスタの前記ゲート端子をグランドに接続する放電回路を更に備える、請求項１に記載の点灯回路。 The lighting circuit of claim 1, further comprising a discharge circuit that connects the gate terminal of the at least one field effect transistor to ground when the input voltage exceeds a threshold voltage. 前記放電回路は、前記少なくとも一つの電界効果トランジスタのゲート端子をグランド電位に接続する放電スイッチと、前記入力電圧を抵抗分圧して分圧電圧を生成して前記放電スイッチに供給する分圧回路を含む、請求項３に記載の点灯回路。 The discharge circuit includes a discharge switch that connects a gate terminal of the at least one field effect transistor to a ground potential, and a voltage divider circuit that divides the input voltage with a resistor to generate a divided voltage and supplies the generated divided voltage to the discharge switch. The lighting circuit according to claim 3, comprising: 前記少なくとも一つの電界効果トランジスタのゲート端子を保護する保護回路を更に備える、請求項１に記載の点灯回路。 The lighting circuit according to claim 1, further comprising a protection circuit that protects a gate terminal of the at least one field effect transistor. 前記保護回路は、少なくとも一つのツェナーダイオードを含む、請求項５に記載の点灯回路。 The lighting circuit according to claim 5, wherein the protection circuit includes at least one Zener diode. 前記少なくとも一つの電界効果トランジスタがＮチャンネル電界効果トランジスタである、請求項１乃至６のいずれか一項に記載の点灯回路。 A lighting circuit according to any one of claims 1 to 6, wherein the at least one field effect transistor is an N-channel field effect transistor. 前記Ｍ個が３個を示し、前記Ｍ－１以下の個数が１個を示す、請求項１乃至６のいずれか一項に記載の点灯回路。 7. The lighting circuit according to claim 1, wherein the M number indicates three, and the number equal to or less than M-1 indicates one. 請求項１乃至６のいずれか一項に記載の点灯回路を含む車両用灯具。 A vehicle lamp comprising the lighting circuit according to any one of claims 1 to 6. Ｍ（Ｍは２以上の自然数を示す）個の半導体発光素子が直列に接続された半導体発光素子の直列回路に含まれるＭ－１以下の個数の半導体発光素子に対して並列に接続されたバイパス回路がターンオフするターンオフ電圧に向けて入力電圧が増加する時、前記バイパス回路に流れるバイパス電流が漸減し、かつ前記Ｍ－１以下の個数の半導体発光素子に流れる駆動電流が漸増するように構成される、車両灯具用の点灯回路。 A bypass connected in parallel to M-1 or less semiconductor light emitting elements included in a series circuit of semiconductor light emitting elements in which M (M represents a natural number of 2 or more) semiconductor light emitting elements are connected in series. When the input voltage increases toward a turn-off voltage at which the circuit is turned off, the bypass current flowing through the bypass circuit gradually decreases, and the drive current flowing through the M-1 or less semiconductor light-emitting elements gradually increases. A lighting circuit for vehicle lighting equipment. 前記入力電圧を抵抗分圧して前記バイパス回路に分圧電圧を供給する分圧回路を含む、請求項１０に記載の車両灯具用の点灯回路。 The lighting circuit for a vehicle lamp according to claim 10, further comprising a voltage dividing circuit that divides the input voltage with resistance and supplies the divided voltage to the bypass circuit. 前記バイパス回路は、少なくとも一つの電界効果トランジスタを含み、
前記少なくとも一つの電界効果トランジスタは、前記Ｍ－１以下の個数の半導体発光素子のアノード端子に接続されたドレイン端子、前記Ｍ－１以下の個数の半導体発光素子のカソード端子に接続されたソース端子、及び前記分圧電圧が供給されるゲート端子を有する、請求項１１に記載の車両灯具用の点灯回路。 the bypass circuit includes at least one field effect transistor;
The at least one field effect transistor has a drain terminal connected to an anode terminal of the M-1 or less semiconductor light emitting devices, and a source terminal connected to a cathode terminal of the M-1 or less semiconductor light emitting devices. 12. The lighting circuit for a vehicle lamp according to claim 11, further comprising a gate terminal to which the divided voltage is supplied.
JP2022087856A 2022-05-30 2022-05-30 Lightning circuit for vehicle lightning tool, and lightning tool for vehicle including the same Pending JP2023175424A (en)

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