EP2999312B1

EP2999312B1 - Lamp drive power supply and method for controlling lamp drive power supply

Info

Publication number: EP2999312B1
Application number: EP13852349.3A
Authority: EP
Inventors: Toyotaka Takashima; Teppei Matsuzaki; Ryohei Kitamura
Original assignee: Honda Motor Co Ltd; Shindengen Electric Manufacturing Co Ltd
Current assignee: Honda Motor Co Ltd; Shindengen Electric Manufacturing Co Ltd
Priority date: 2013-05-13
Filing date: 2013-05-13
Publication date: 2017-10-25
Anticipated expiration: 2033-05-13
Also published as: WO2014184847A1; EP2999312A1; BR112014018489A8; EP2999312A4; TW201448670A; ES2651323T3; BR112014018489A2; JP5684432B1; JPWO2014184847A1; BR112014018489B1; TWI554153B; ZA201405502B; CN104509212A; CN104509212B

Description

[Technical Field]

The present invention relates to an LED lamp lighting device according to the preamble of claim 1 and to a control method of the LED lamp lighting device. An LED lamp lighting device according to the preamble of claim 1 is known from WO 2012/127 515 A1 .

[Background Art]

Generally, LED (Light Emitting Diode) lamps can be driven at low voltages with longer life, lower power consumption, higher response speeds, and higher shock resistance as compared with filament lamps (bulb lamps), achieving smaller sizes and lighter weights.
Thus, LED lamps can be suitably used for, for example, vehicle head lamps.
For example, Japanese Patent Laid-Open No. 2012-160413 describes an LED lamp lighting device as an example of a LED lamp driver.
An the LED lamp lighting device described in Japanese Patent Laid-Open No. 2012-160413 detects an LED open error according to the voltage of the negative terminal of an LED array of LED lamps connected in series. If the LED lamp lighting device detects the LED open error, an LED voltage applied to a positive terminal is increased until recovery from the LED open error. A voltage at the time of recovery from the LED open error is determined as a temporary LED voltage. If the LED array is illuminated, the LED lamp lighting device controls a power supply so as to apply an LED voltage that is larger than the temporary LED voltage by a predetermined value.
Thus, the LED open error can be detected with a simple circuit configuration and an LED voltage can be determined without causing the LED open error.
As described above, the multiple LED lamps are connected in series in the LED lamp lighting device.
If one of the connected LED lamps becomes defective, a driving current may be interrupted. Thus, all the LED lamps connected in series may be turned off.
In a typical bulb lamp lighting device, a broken lamp cannot be illuminated and an unbroken lamp can be illuminated by a user's switch operation.
As described above, if one of the LED lamps connected in series becomes defective, the lighting operation of the LED lamp lighting device is disadvantageously different from that of a typical bulb lamp lighting device.

[Summary of Invention]

[Solution to Problem]

An LED lamp lighting device, according to an embodiment of an aspect of the present invention, that is connected between a first power supply terminal on a low potential side of a lamp driving power supply and a second power supply terminal on a high potential side of the lamp driving power supply, receives a driving current from the lamp driving power supply, and causes the driving current to illuminate a plurality of LED lamps connected in series,
the LED lamp lighting device comprising:

a first terminal connected to the first power supply terminal;
a second terminal connected to the second power supply terminal;
a first lamp circuit including one LED lamp or a plurality of LED lamps in a series connection, with a first end connected to the first terminal;
a second lamp circuit including one LED lamp or a plurality of LED lamps in a series connection, with a first end connected to a second end of the first lamp circuit and a second end connected to the second terminal;
a switch circuit that switches an electrical connection between a reference node connected to the second end of the first lamp circuit and a first contact and an electrical connection between the reference node and a second contact;
a control switch element with a first end connected to the first terminal and a second end connected to the first contact or the first end connected to the second contact and the second end connected to the second terminal; and
a switch control circuit that controls the control switch element according to a potential difference between the first end and the second end of the control switch element,
wherein the switch control circuit turns on the control switch element if the potential difference between the first end and the second end of the control switch element is at least a predetermined reference voltage, and
the switch control circuit turns off the control switch element if the potential difference between the first end and the second end of the control switch element is smaller than the reference voltage.

In the LED lamp lighting device,
the lamp driving power supply has a constant voltage control function and a constant current control function,
if a current is capable of passing through any one of the LED lamps of the first lamp circuit and the second lamp circuit, a constant current is applied to the LED lamp by the constant current control function, and
if a current is incapable of passing through the LED lamps of the first lamp circuit and the second lamp circuit, an output voltage between the first power supply terminal and the second power supply terminal is increased to a predetermined specified voltage and then is kept constant by the constant voltage control function.
In the LED lamp lighting device,
the control switch element is a thyristor with a cathode connected to the second contact and an anode connected to the second terminal.
In the LED lamp lighting device,
the switch control circuit comprises:

a first control resistor with a first end connected to the second contact and a second end connected to a gate of the thyristor;
a second control resistor with a first end connected to the second end of the first control resistor; and
a Zener diode with an anode connected to a second end of the second control resistor and a cathode connected to the second terminal.

In the LED lamp lighting device,
the control switch element is a thyristor with a cathode connected to the first terminal and an anode connected to the first contact.
In the LED lamp lighting device,
the switch control circuit comprises:

a first control resistor with a first end connected to the first terminal and a second end connected to a gate of the thyristor;
a second control resistor with a first end connected to the second end of the first control resistor; and
a Zener diode with an anode connected to a second end of the second control resistor and a cathode connected to the first contact.

In the LED lamp lighting device,
the lamp driving power supply comprises:

a power supply switch element with a first end connected to the first input terminal and a second end connected to the first power supply terminal;
a capacitor with a first end connected to the second end of the power supply switch element and a second end connected to the second input terminal; and
a driving control circuit that controls the power supply switch element so as to keep a constant current between the second input terminal and the second power supply terminal if a current is applied between the second input terminal and the second power supply terminal, and controls the power supply switch element so as to keep a voltage between the first power supply terminal and the second power supply terminal at a predetermined specified voltage if no current is applied between the second input terminal and the second power supply terminal.

In the LED lamp lighting device,
the lamp driving power supply further comprises a sensing resistor connected between the second input terminal and the second power supply terminal,
the driving control circuit controls the power supply switch element so as to keep a constant current passing through the sensing resistor if a current passes through the sensing resistor, and
the driving control circuit controls the power supply switch element so as to keep a voltage between the first power supply terminal and the second power supply terminal at the predetermined specified voltage if no current passes through the sensing resistor.
In the LED lamp lighting device,
the switch circuit allows a user to manually switch an electrical connection between the reference node and the first contact and an electrical connection between the reference node and the second contact.
A control method of an LED lamp lighting device, according to an embodiment of an aspect of the present invention, the LED lamp lighting device being connected between a first power supply terminal on a low potential side of a lamp driving power supply and a second power supply terminal on a high potential side of the lamp driving power supply, receiving a driving current from the lamp driving power supply, and causing the driving current to illuminate a plurality of LED lamps connected in series, the LED lamp lighting device comprising: a first terminal connected to the first power supply terminal; a second terminal connected to the second power supply terminal; a first lamp circuit including one LED lamp or a plurality of LED lamps in a series connection, with a first end connected to the first terminal; a second lamp circuit including one LED lamp or a plurality of LED lamps in a series connection, with a first end connected to a second end of the first lamp circuit and a second end connected to the second terminal; a switch circuit that switches an electrical connection between a reference node connected to the second end of the first lamp circuit and a first contact and an electrical connection between the reference node and a second contact; a control switch element with a first end connected to the first terminal and a second end connected to the first contact or the first end connected to the second contact and the second end connected to the second terminal; and a switch control circuit that controls the control switch element according to a potential difference between the first end and the second end of the control switch element,
the control method comprising:

turning on the control switch element if the potential difference between the first end and the second end of the control switch element is at least a predetermined reference voltage, and
turning off the control switch element if the potential difference between the first end and the second end of the control switch element is smaller than the reference voltage.

An LED lamp lighting device, according to an embodiment, is connected between a first power supply terminal on a low potential side of a lamp driving power supply and a second power supply terminal on a high potential side of the lamp driving power supply, receives a driving current from the lamp driving power supply, and causes the driving current to illuminate a plurality of LED lamps connected in series.
Furthermore, the LED lamp lighting device comprises a first terminal connected to the first power supply terminal; a second terminal connected to the second power supply terminal; a first lamp circuit including one LED lamp or a plurality of LED lamps in a series connection, with a first end connected to the first terminal; a second lamp circuit including one LED lamp or a plurality of LED lamps in a series connection, with a first end connected to a second end of the first lamp circuit and a second end connected to the second terminal; a switch circuit that switches an electrical connection between a reference node connected to the second end of the first lamp circuit and a first contact and an electrical connection between the reference node and a second contact; a control switch element with a first end connected to the first terminal and a second end connected to the first contact or the first end connected to the second contact and the second end connected to the second terminal; and a switch control circuit that controls the control switch element according to a potential difference between the first end and the second end of the control switch element.
Furthermore, the switch control circuit turns on the control switch element if the potential difference between the first end and the second end of the control switch element is at least a predetermined reference voltage, and the switch control circuit turns off the control switch element if the potential difference between the first end and the second end of the control switch element is smaller than the reference voltage.
With this configuration, defective one of the LED lamps connected in series can be skipped to turn on the other LED lamps.
In other words, according to an LED lamp lighting device of the present invention, an operation for a defective LED lamp of the LED lamp lighting device can be similar to that for a typical bulb lamp lighting device.

[Brief Description of Drawings]

[FIG. 1] Figure 1 is a circuit diagram showing an example of the configuration of a system including an LED lamp lighting device 100 according to a first embodiment as an aspect of the present invention.
[FIG. 2] Figure 2 is a circuit diagram showing an example in which the switch circuit of the LED lamp lighting device in Figure 1 electrically connects the reference node and the second contact.
[FIG. 3] Figure 3 is a circuit diagram showing an example in which the switch circuit of the LED lamp lighting device in Figure 1 electrically connects the reference node and the first contact.
[FIG. 4] Figure 4 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the second contact NS2.
[FIG. 5] Figure 5 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the first contact NS1.
[FIG. 6] Figure 6 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the second contact NS2.
[FIG. 7] Figure 7 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the first contact NS1.
[FIG. 8] Figure 8 shows the relationship between the on/off of switching of a typical bulb lamp lighting device and the lighting of each bulb lamp.
[FIG. 9] Figure 9 shows the relationship between the on/off of the switch circuit of the LED lamp lighting device 100 and the lighting of the LED lamps according to the first embodiment shown in Figure 1.
[FIG. 10] Figure 10 is a circuit diagram showing an example of the configuration of a system including the LED lamp lighting device 100 according to the second embodiment, which is an aspect of the present invention.

[Description of Embodiments]

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

[First Embodiment]

Figure 1 is a circuit diagram showing an example of the configuration of a system including an LED lamp lighting device 100 according to a first embodiment as an aspect of the present invention. Figure 1 shows an example of an LED lamp lighting device used for a vehicle head lamp.
As shown in Figure 1, the LED lamp lighting device 100 is connected to a lamp driving power supply 10. The lamp driving power supply 10 is connected to an alternating-current generator G.
The alternating-current generator G is a single-phase alternating-current generator that rotates in synchronization with, for example, a vehicle engine so as to generate an alternating current.
The alternating-current generator G has one end G1 that is connected to a first input terminal TI1 of the lamp driving power supply 10 and the other end G2 that is grounded. The alternating-current generator G outputs a generated alternating voltage VA, to the lamp driving power supply 10.
Furthermore, a first power supply terminal TS1 on the negative voltage side (low potential side) of the lamp driving power supply 10 is connected to a first terminal Ta1 of the LED lamp lighting device 100, and a second power supply terminal TS2 on the positive voltage side (high potential side) of the lamp driving power supply 10 is connected to a second terminal Ta2 of the LED lamp lighting device 100. The lamp driving power supply 10 supplies a driving current to the LED lamp lighting device 100. The driving current for illuminating an LED lamp is obtained by rectifying the alternating current of the alternating-current generator G.
Specifically, the LED lamp lighting device 100 is connected between the first power supply terminal TS1 on the low potential side and the second power supply terminal TS2 on the high potential side of the lamp driving power supply 10. The LED lamp lighting device 100 receives the supplied driving current from the lamp driving power supply 10 and the driving current illuminates LED lamps connected in series.
For example, as shown in Figure 1, the LED lamp lighting device 100 includes the first terminal Ta1, the second terminal Ta2, a first lamp circuit L1, a second lamp circuit L2, a switch circuit SW1, a control switch element SCR, and a switch control circuit C1.
The first terminal Ta1 is connected to the first power supply terminal TS1.
The second terminal Ta2 is connected to the second power supply terminal TS2.
The first lamp circuit L1 includes one LED lamp or a plurality of LED lamps in a series connection. One end of the first lamp circuit L1 is connected to the first terminal Ta1.
In the example of Figure 1, the first lamp circuit L1 includes two LED lamps LH1 and LH2 connected in series.
As shown in Figure 1, one end of the first lamp circuit L1 is located on the cathode side of the LED lamp LH1 of the first lamp circuit L1.
Moreover, the other end of the first lamp circuit L1 is located on the anode side of the LED lamp LH2 of the first lamp circuit L1.
The LED lamps of the first lamp circuit L1 are, for example, high beam lamps for vehicle head lamps (e.g., headlights for driving).
The second lamp circuit L2 includes one LED lamp or a plurality of LED lamps in a series connection. One end of the second lamp circuit L2 is connected to the other end of the first lamp circuit L1 and the other end of the second lamp circuit L2 is connected to the second terminal Ta2.
In the example of Figure 1, the second lamp circuit L2 includes two LED lamps LL1 and LL2 connected in series.
As shown in Figure 1, one end of the second lamp circuit L2 is located on the cathode side of the LED lamp LL1 of the second lamp circuit L2. The other end of the second lamp circuit L2 is located on the anode side of the LED lamp LL2 of the second lamp circuit L2.
The LED lamps of the second lamp circuit L2 are, for example, low beam lamps for the head lamps (e.g., headlights for passing).
The switch circuit SW1 is electrically connected between a reference node NB connected to the other end of the first lamp circuit L1 and a first contact NS1 connected to the first terminal Ta1 or between the reference node NB and a second contact NS2.
In other words, the switch circuit SW1 switches an electrical connection between the reference node NB and the first contact NS1 and an electrical connection between the reference node NB and the second contact NS2.
For example, when the reference node NB connected to the other end of the first lamp circuit L1 and the first contact NS1 connected to the first terminal Ta1 are electrically connected to each other by operating the switch circuit SW1, the LED lamps LH1 and LH2 of the first lamp circuit L1 are short-circuited.
Thus, a current does not pass through the first lamp circuit L1, so that the LED lamps LL1 and LL2 of the second lamp circuit L2 illuminate and the LED lamps LH1 and LH2 of the first lamp circuit L1 do not illuminate.
When the reference node NB connected to the other end of the first lamp circuit L1 is electrically connected to the second contact NS2 by operating the switch circuit SW1, a current passes through the LED lamps LH1 and LH2 of the first lamp circuit L1.
Thus, all the LED lamps LH1, LH2, LL1, and LL2 of the first and second lamp circuits L1 and L2 illuminate.
Specifically, the switch circuit SW1 is a switch for switching a high beam (the first lamp circuit L1 and the second lamp circuit L2 illuminate) Hi and a low beam (the second lamp circuit L2 illuminates) Lo of the vehicle headlight described above.
The switch circuit SW1 is manually controlled by a user. Specifically, the switch circuit SW1 switches an electrical connection between the reference node NB and the first contact NS1 and an electrical connection between the reference node NB and the second contact NS2 in response to a manual operation of the user.
For example, as shown in Figure 1, one end of the control switch element SCR is connected to the second contact NS2 and the other end of the control switch element SCR is connected to the second terminal Ta2.
The control switch element SCR is a thyristor. The cathode of the thyristor is connected to the second contact NS2 and the anode of the thyristor is connected to the second terminal Ta2.
As will be described later, one end of the control switch element SCR may be connected to the first terminal Ta1 and the other end of the control switch element SCR may be connected to the first contact NS1.
The switch control circuit C1 controls the control switch element SCR according to a potential difference between one end and the other end of the control switch element SCR (a potential difference between the second contact NS2 and the second terminal Ta2).
For example, the switch control circuit C1 turns on the control switch element SCR if a potential difference (absolute value) between one end and the other end of the control switch element SCR (between the second contact NS2 and the second terminal Ta2) is not larger than a predetermined reference voltage. The potential difference is compared with the value (absolute value) of the reference voltage (also in the following description).
The switch control circuit C1 turns off the control switch element SCR if a potential difference (absolute value) between one end and the other end of the control switch element SCR (between the second contact NS2 and the second terminal Ta2) is smaller than the reference voltage.
As shown in Figure 1, the switch control circuit C1 includes, for example, a first control resistor Rs, a second control resistor Rt, and a Zener diode Ze. One end of the first control resistor Rs is connected to the second contact NS2 and the other end of the first control resistor Rs is connected to the gate (control terminal) of the thyristor (control switch element) SCR.
One end of the second control resistor Rt is connected to the other end of the first control resistor Rs.
The anode of the Zener diode Ze is connected to the other end of the second control resistor Rt and the cathode of the Zener diode Ze is connected to the second terminal Ta2.
The switch control circuit C1 is configured to monitor the voltage of the second contact NS2 by means of the first control resistor Rs, the second control resistor Rt, and the Zener diode Ze.
Specifically, if the voltage value (absolute value) of the second contact NS2 exceeds the reference voltage, the Zener diode Ze conducts so as to pass a current through the second control resistor Rt.
The Zener diode Ze conducts so as to pass a current through the second control resistor Rt, generating a voltage between the anode and the gate of the control switch element (thyristor) SCR. The voltage allows the passage of a gate current through the gate of the control switch element SCR, turning on the control switch element SCR.
The reference voltage can be set at a desired value according to the resistance values of the first control resistor Rs and the second control resistor Rt and the breakdown voltage of the Zener diode Ze.
The LED lamp lighting device 100 configured thus includes the LED lamps LH1, LH2, LL1, and LL2 connected in series between the first terminal Ta1 and the second terminal Ta2, and can switch illuminated ones of the LED lamps LH1, LH2, LL1, and LL2 (Figure 1).
As shown in Figure 1, the lamp driving power supply 10 includes, for example, the first input terminal TI1, a second input terminal TI2, the first power supply terminal TS1, the second power supply terminal TS2, a power supply switch element SX, a capacitor CX, a sensing resistor RX, and a driving control circuit CON.
The first power supply terminal TS1 on the low potential side is connected to the first terminal Ta1.
The second power supply terminal TS2 on the high potential side is connected to the second terminal Ta2.
The first input terminal TI1 is connected to the one end G1 of the alternating-current generator G.
The second input terminal TI2 is connected to the other end G2 of the alternating-current generator G via the ground.
One end of the power supply switch element SX is connected to the first input terminal TI1 and the other end of the power supply switch element SX is connected to the first power supply terminal TS1.
As shown in Figure 1, the power supply switch element SX is, for example, a thyristor. The cathode of the thyristor is connected to the first input terminal TI1 and the anode of the thyristor is connected to the first power supply terminal TS1. The gate of the thyristor receives a control signal from the driving control circuit CON.
One end of the capacitor CX is connected to the other end of the power supply switch element SX and the other end of the capacitor CX is connected to the second input terminal TI2 (the other end G2 of the alternating-current generator G). The capacitor CX is a smoothing capacitor (electrolytic capacitor).
The sensing resistor RX is connected between the second input terminal TI2 and the second power supply terminal TS2.
If a current IX is applied between the second input terminal TI2 and the second power supply terminal TS2, the driving control circuit CON controls the power supply switch element SX so as to keep a constant current applied between the second input terminal TI2 and the second power supply terminal TS2.
If the current IX is not applied between the second input terminal TI2 and the second power supply terminal TS2, the driving control circuit CON controls the power supply switch element SX so as to set a voltage between the first power supply terminal TS1 and the second power supply terminal TS2 at a predetermined specified voltage.
In the example of Figure 1, the driving control circuit CON detects the current IX passing through the sensing resistor RX.
If the current IX passes through the sensing resistor RX, the driving control circuit CON controls the power supply switch element SX so as to keep constant the current IX passing through the sensing resistor RX.
Thus, the power supply switch element (thyristor) SX performs half-wave rectification on a voltage on the negative-phase side of the alternating voltage VA outputted from the alternating-current generator G, under the control of the driving control circuit CON. This supplies a driving current to the LED lamp lighting device 100.
The power supply switch element (thyristor) SX charges the capacitor CX during an on period.
The capacitor CX is a rectifying/smoothing capacitor that supplies a current to the LED lamp lighting device 100 during the off period of the power supply switch element (thyristor) SX.
In other words, the driving control circuit CON controls the time of conduction (ignition phase) of the power supply switch element (thyristor) SX so as to keep constant the effective value or the mean value of a current passing through the LED lamp lighting device 100.
If the current IX does not pass through the sensing resistor RX, the driving control circuit CON controls the power supply switch element SX so as to set a potential difference between the first power supply terminal TS1 and the second power supply terminal TS2 at the predetermined specified voltage.
As described above, the lamp driving power supply 10 has a constant voltage control function and a constant current control function.
Specifically, if the lamp driving power supply 10 can apply a current to the LED lamp of one of the first lamp circuit L1 and the second lamp circuit L2, a constant current is applied to the LED lamp by the constant current control function (outputs a constant current from the second power supply terminal TS2).
In this case, if the current can be applied to the LED lamp, the LED lamp is not defective (is conducting).
If the lamp driving power supply 10 cannot apply a current to any one of the LED lamps of the first lamp circuit L1 and the second lamp circuit L2 (defective), an output voltage between the first power supply terminal TS1 and the second power supply terminal TS2 is increased to the predetermined specified voltage and is kept constant by the constant voltage control function.
If a current cannot be applied to the LED lamp, the LED lamp is defective (broken) with an open load.
The operations of the LED lamp lighting device 100 configured thus will be described below.
Figure 2 is a circuit diagram showing an example in which the switch circuit of the LED lamp lighting device in Figure 1 electrically connects the reference node and the second contact. Figure 3 is a circuit diagram showing an example in which the switch circuit of the LED lamp lighting device in Figure 1 electrically connects the reference node and the first contact.
For example, in the example of Figure 2, the switch circuit SW1 electrically connects the reference node NB and the first contact NS1.
In other words, the switch circuit SW1 is switched by a user so as to select a high beam Hi.
Thus, the current IX supplied from the lamp driving power supply 10 passes through "the second terminal Ta2, the second lamp circuit L2, the first lamp circuit L1, and then the first terminal Ta1" (Figure 2).
Thus, all the LED lamps LH1, LH2, LL1, and LL2 connected in series are illuminated.
After that, for example, the switch circuit SW1 is operated by the user to switch from an electrical connection between the reference node NB and the second contact NS2 to an electrical connection between the reference node NB and the first contact NS1 connected to the first terminal Ta1 (Figure 3); meanwhile, the switch control circuit C1 turns off the control switch element SCR.
In other words, the switch circuit SW1 is switched by the user so as to select a low beam Lo.
Thus, the current IX supplied from the lamp driving power supply 10 passes through "the second terminal Ta2, the second lamp circuit L2, the switch circuit SW1, and then the first terminal Ta1".
In other words, the LED lamp lighting device 100 short-circuits the illuminated LED lamps LH1 and LH2 out of the plurality of LED lamps LH1, LH2, LL1, and LL2 connected in series from the state in which all of the LED lamps LH1, LH2, LL1, and LL2 are illuminated.
The illuminated LED lamps LH1 and LH2 are short-circuited so as to interrupt a current passing through the LED lamps LH1 and LH2. Hence, the LED lamps LH1 and LH2 are turned off.
In this way, the LED lamp lighting device 100 short-circuits some of the illuminated LED lamps from a state in which some of the LED lamps connected in series are illuminated. The illuminated LED lamps are short-circuited so as to interrupt a current passing through the LED lamps. Hence, the LED lamps are turned off.
In Figures 2 and 3, the switch control circuit C1 is not operated and thus does not affect the current IX.
In the following explanation, the switch control circuit C1 of the LED lamp lighting device 100 is operated.
Figure 4 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the second contact NS2. Figure 5 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the first contact NS1. Figure 6 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the second contact NS2. Figure 7 is a circuit diagram showing an example in which the switch circuit SW1 of the LED lamp lighting device 100 in Figure 1 electrically connects the reference node NB and the first contact NS1. Figure 8 shows the relationship between the on/off of switching of a typical bulb lamp lighting device and the lighting of each bulb lamp. Figure 9 shows the relationship between the on/off of the switch circuit of the LED lamp lighting device 100 and the lighting of the LED lamps according to the first embodiment shown in Figure 1.
In Figures 4 and 5, the LED lamp LL2 of the second lamp circuit L2 is defective (broken). In Figures 6 and 7, the LED lamp LH1 of the first lamp circuit L1 is defective (broken).
For example, the state of the switch circuit SW1 in the example of Figure 4 is similar to that of Figure 2 described above.
In other words, the switch circuit SW1 is switched by the user so as to select the high beam lamp Hi.
As shown in Figure 4, the switch circuit SW1 is operated so as to electrically connect the reference node NB and the second contact NS2 while the LED lamp LL2 of the second lamp circuit L2 is defective. Also in this case, a current does not pass through the second lamp circuit L2.
As described above, the switch control circuit C1 turns off the control switch element SCR if a potential difference (absolute value) between one end and the other end of the control switch element SCR (between the second contact NS2 and the second terminal Ta2) is smaller than the reference voltage.
Thus, the current IX is not applied.
A voltage between the first power supply terminal TS1 and the second power supply terminal TS2 is increased to the specified voltage by the constant voltage control function of the lamp driving power supply 10.
Thus, the switch control circuit C1 turns on the control switch element SCR if a potential difference (absolute value) between one end and the other end of the control switch element SCR (between the second contact NS2 and the second terminal Ta2) is not smaller than the reference voltage.
Thus, a current is applied between the second contact NS2 and the second terminal Ta2.
Specifically, the current IX supplied from the lamp driving power supply 10 passes through "the second terminal Ta2, the control switch element SCR, the switch circuit SW1, the first lamp circuit L1, and then the first terminal Ta1."
Thus, the LED lamps LH1 and LH2 of the first lamp circuit L1 are illuminated (Figure 9).
In this way, the switch control circuit C1 is operated so as to skip the defective LED lamp LL2 and illuminate the normal LED lamps LH1 and LH2 (two lamps).
In the example of Figure 5, the state of the switch circuit SW1 is similar to that of Figure 3 described above.
Specifically, the switch circuit SW1 is switched by the user so as to select the low beam lamp Lo.
As shown in Figure 5, the switch circuit SW1 is operated so as to electrically connect the reference node NB and the first contact NS1 while the LED lamp LL2 of the second lamp circuit L2 is defective. Also in this case, a current does not pass through the second lamp circuit L2.
Thus, the first and second lamp circuits L1 and L2 are turned off (Figure 9).
In the example of Figure 6, the state of the switch circuit SW1 is similar to that of Figure 2 described above.
Specifically, the switch circuit SW1 is switched by the user so as to select the high beam lamp Hi.
As shown in Figure 6, the switch circuit SW1 is operated so as to electrically connect the reference node NB and the second contact NS2 while the LED lamp LH1 of the first lamp circuit L1 is defective. Also in this case, a current does not pass through the first lamp circuit L1.
Thus, the first and second lamp circuits L1 and L2 are turned off (Figure 9).
In the example of Figure 7, the state of the switch circuit SW1 is similar to that of Figure 3 described above.
Specifically, the switch circuit SW1 is switched by the user so as to select the low beam lamp Lo.
Thus, the current IX supplied from the lamp driving power supply 10 passes through "the second terminal Ta2, the second lamp circuit L2, the switch circuit SW1, and then the first terminal Ta1."
This illuminates the two high beam lamps Hi (Figure 9).
In Figures 5 to 7, the switch control circuit C1 is not operated and thus does not affect a current i.
As described above, an operation for the defective LED lamp of the LED lamp lighting device 100 according to the first embodiment (Figure 9) is identical to that for the defective bulb lamp of the typical bulb lamp lighting device in Figure 8.
As described above, defective one of the LED lamps connected in series can be skipped to turn on the other LED lamps in the LED lamp lighting device 100.
In other words, in the LED lamp lighting device according to the present embodiment, an operation for a failure in the LED lamp can be identical to that for the typical bulb lamp lighting device.
Also in the event of a failure in the LED lamp, the lighting of the LED lamp can be controlled by a user operation of the switch circuit.

[Second Embodiment]

As described above, one end of a control switch element SCR may be connected to a first terminal Ta1 and the other end of the control switch element SCR may be connected to a first contact NS1.
In a second embodiment, one end of the control switch element SCR is connected to the first terminal Ta1 and the other end of the control switch element SCR is connected to the first contact NS1 in an LED lamp lighting device 100.
Figure 10 is a circuit diagram showing an example of the configuration of a system including the LED lamp lighting device 100 according to the second embodiment, which is an aspect of the present invention. In Figure 10, the same reference numerals as those of Figure 1 indicate the same configurations as those of the first embodiment.
As shown in Figure 10, as in the first embodiment, the LED lamp lighting device 100 includes the first terminal Ta1, a second terminal Ta2, a first lamp circuit L1, a second lamp circuit L2, a switch circuit SW1, the control switch element SCR, and a switch control circuit C1.
In the second embodiment, one end of the control switch element SCR is connected to the first terminal Ta1 and the other end of the control switch element SCR is connected to the first contact NS1.
The control switch element SCR is a thyristor. The cathode of the thyristor is connected to the first terminal Ta1 and the anode of the thyristor is connected to the first contact NS1.
The switch control circuit C1 controls the control switch element SCR according to a potential difference between one end and the other end of the control switch element SCR (a potential difference between the first contact NS1 and the first terminal Ta1).
For example, as in the first embodiment, the switch control circuit C1 includes a first control resistor Rs, a second control resistor Rt, and a Zener diode Ze.
One end of the first control resistor Rs is connected to the first terminal Ta1 and the other end of the first control resistor Rs is connected to the gate (control terminal) of the thyristor (control switch element) SCR.
One end of the second control resistor Rt is connected to the other end of the first control resistor Rs.
The anode of the Zener diode Ze is connected to the other end of the second control resistor Rt and the cathode of the Zener diode Ze is connected to the first contact NS1.
The switch control circuit C1 is configured to monitor a voltage between the first terminal Ta1 and the first contact NS1 by means of the first control resistor Rs, the second control resistor Rt, and the Zener diode Ze.
Specifically, if a potential difference value (absolute value) between one end and the other end of the control switch element SCR (between the first terminal Ta1 and the first contact NS1) exceeds the reference voltage, the Zener diode Ze conducts so as to pass a current through the second control resistor Rt.
The Zener diode Ze conducts so as to pass a current through the second control resistor Rt, generating a voltage between the anode and the gate of the control switch element (thyristor) SCR. The voltage allows the passage of a gate current through the gate of the control switch element SCR, turning on the control switch element SCR.
The reference voltage can be set at a desired value according to the resistance values of the first control resistor Rs and the second control resistor Rt and the breakdown voltage of the Zener diode Ze.
Other configurations and operations of the LED lamp lighting device 100 according to the second embodiment are similar to those of the first embodiment.
Thus, according to the LED lamp lighting device of the present embodiment, defective one of the LED lamps connected in series can be skipped to turn on the other LED lamps as in the first embodiment.
In other words, according to the LED lamp lighting device of the present embodiment, an operation for a defective LED lamp can be similar to that for a typical bulb lamp lighting device as in the first embodiment.
Also in the event of a failure in the LED lamp, the lighting of the LED lamp can be controlled by a user operation of the switch circuit.
In the foregoing embodiments, the LED lamp of the first lamp circuit is a high beam lamp for a vehicle head lamp and the LED lamp of the second lamp circuit is a low beam lamp for the head lamp. However, the LED lamp of the first lamp circuit may be a low beam lamp for a vehicle head lamp and the LED lamp of the second lamp circuit may be a high beam lamp for the head lamp.
The embodiments are merely exemplary and do not limit the scope of the invention.

[Reference Signs List]

10: lamp driving power supply
100: LED lamp lighting device
G: alternating-current generator
G1: one end of the alternating-current generator
G2: the other end of the alternating-current generator
Ta1: first terminal
Ta2: second terminal
IX: current
TI1: first input terminal
TI2: second input terminal
TS1: first power supply terminal
TS2: second power supply terminal
SX: power supply switch element
CX: capacitor
RX: sensing resistor
CON: driving control circuit
Rb: resistor
Dr1: first diode
Dr2: second diode
L1: first lamp circuit
L2: second lamp circuit
SW1: switch circuit
SCR: control switch element
C1: switch control circuit
LH1, LH2, LL1, LL2 LED: lamp

Claims

An LED lamp lighting device (100) that is connected between a first power supply terminal (TS1) on a low potential side of a lamp driving power supply (10) and a second power supply terminal (TS2) on a high potential side of the lamp driving power supply (10), receives a driving current from the lamp driving power supply (10), and causes the driving current to illuminate a first lamp circuit and a second lamp circuit connected in series, the LED lamp lighting device (100) comprising:
a first terminal (Ta1) connected to the first power supply terminal (TS1);

a second terminal (Ta2) connected to the second power supply terminal (TS2); said first lamp circuit (L1) including one LED lamp or a plurality of series connected LED lamps (LH1, LH2), with a first end connected to the first terminal (Ta1); and said second lamp circuit including one LED lamp or a plurality of series connected LED lamps (L1) (LL1, LL2), with a first end connected to a second end of the first lamp circuit and a second end connected to the second terminal (Ta2); characterized by

a switch circuit (SW1) comprising a reference node (NB) connected to the second end of the first lamp circuit (L1) and said switch circuit is operable to electrically connect said reference node between a first contact (NS1) and and a second contact (NS2);

a control switch element (SCR) with a first end connected to the first terminal (Ta1) and a second end connected to the first contact (NS1) or the first end connected to the second contact (Ta2) and the second end connected to the second terminal (NS2); and

a switch control circuit (C1) that controls the control switch element (SCR) according to a potential difference between the first end and the second end of the control switch element (SCR),

wherein the switch control circuit (C1) turns on the control switch element (SCR) if the potential difference between the first end and the second end of the control switch element (SCR) is at least a predetermined reference voltage, and

the switch control circuit (C1) turns off the control switch element (SCR) if the potential difference between the first end and the second end of the control switch element (SCR) is smaller than the reference voltage.
The LED lamp lighting device according to claim 1, wherein the lamp driving power supply (10) has a constant voltage control function and a constant current control function,
if a current is capable of passing through any one of the LED lamps of the first lamp circuit (L1) and the second lamp circuit (L2), a constant current is applied to the LED lamp by the constant current control function, and
if a current is incapable of passing through the LED lamps of the first lamp circuit (L1) and the second lamp circuit (L2), an output voltage between the first power supply terminal (TS 1) and the second power supply terminal (TS2) is increased to a predetermined specified voltage and then is kept constant by the constant voltage control function.
The LED lamp lighting device according to claim 1, wherein the control switch element (SCR) is a thyristor with a cathode connected to the second contact (NS2) and an anode connected to the second terminal (Ta2).
The LED lamp lighting device according to claim 3, wherein the switch control circuit (C1) comprises:
a first control resistor (Rs) with a first end connected to the second contact (NS2)and a second end connected to a gate of the thyristor (SCR);

a second control resistor (Rt) with a first end connected to the second end of the first control resistor (Rs); and

a Zener diode (Ze) with an anode connected to a second end of the second control resistor (Rt) and a cathode connected to the second terminal (Ta2).
The LED lamp lighting device according to claim 1, wherein the control switch element (SCR) is a thyristor with a cathode connected to the first terminal (Ta1) and an anode connected to the first contact (NS1).
The LED lamp lighting device according to claim 5, wherein the switch control circuit (C1) comprises:
a first control resistor (Rs) with a first end connected to the first terminal (Ta1) and a second end connected to a gate of the thyristor (SCR);

a second control resistor (Rt) with a first end connected to the second end of the first control resistor (Rs); and

a Zener diode (Ze) with an anode connected to a second end of the second control resistor (Rt) and a cathode connected to the first contact (NS1).
The LED lamp lighting device according to claim 1, wherein the lamp driving power supply (10) comprises:
a power supply switch element (SX) with a first end connected to a first input terminal (Tl1) and a second end connected to the first power supply terminal (TS1);

a capacitor (CX) with a first end connected to the second end of the power supply switch element (SX) and a second end connected to a second input terminal (Tl2); and

a driving control circuit (CON) that controls the power supply switch element (SX) so as to keep a constant current between the second input terminal (Tl2) and the second power supply terminal (TS2) if a current is applied between the second input terminal (Tl2) and the second power supply terminal (TS2), and controls the power supply switch element so as to keep a voltage between the first power supply terminal (TS1) and the second power supply terminal (TS2) at a predetermined specified voltage if no current is applied between the second input terminal (Tl2) and the second power supply terminal (TS2).
The LED lamp lighting device according to claim 7, wherein the lamp driving power supply (10) further comprises a sensing resistor (RX) connected between the second input terminal (Tl2) and the second power supply terminal (TS2),
the driving control circuit controls (CON) the power supply switch element (SX) so as to keep a constant current passing through the sensing resistor (RX) if a current passes through the sensing resistor (RX), and
the driving control circuit controls (CON) the power supply switch element (SX) so as to keep a voltage between the first power supply terminal (TS 1) and the second power supply terminal (TS2) at the predetermined specified voltage if no current passes through the sensing resistor (RX).
The LED lamp lighting device according to claim 1, wherein the switch circuit (SW1) allows a user to manually close an electrical connection between the reference node (NB) and the first contact (NS1) and an electrical connection between the reference node (NB) and the second contact (NS2).
A control method of an LED lamp lighting device (100), the LED lamp lighting device being connected between a first power supply terminal (TS 1) on a low potential side of a lamp driving power supply (10) and a second power supply terminal (TS) on a high potential side of the lamp driving power supply (10), receiving a driving current from the lamp driving power supply (10), and causing the driving current to illuminate a first lamp circuit and a second lamp circuit connected in series, and the LED lamp lighting device (100) comprising: a first terminal (Ta1) connected to the first power supply terminal (TS 1); a second terminal (Ta2) connected to the second power supply terminal (TS2); said first lamp circuit (L1) including one LED lamp or a plurality of series connected LED lamps (LH1, LH2), with a first end connected to the first terminal (Ta1); said second lamp circuit (L2) including one LED lamp or a plurality of series connected LED lamps (LL1, LL2), with a first end connected to a second end of the first lamp circuit (L1) and a second end connected to the second terminal (TA2); a switch circuit (SW1) comprising a reference node (NB) connected to the second end of the first lamp circuit (L1) and said switch circuit switches to electrically connect said reference node between a first contact (NS1) and a second contact (NS2); a control switch element (SCR) with a first end connected to the first terminal (TA1) and a second end connected to the first contact (NS1) or the first end connected to the second contact (TA2) and the second end connected to the second terminal (NS2); and a switch control circuit (L1) that controls the control switch element (SCR) according to a potential difference between the first end and the second end of the control switch element (SCR), the control method comprising:
turning on the control switch element (SCR) if the potential difference between the first end and the second end of the control switch element (SCR) is at least a predetermined reference voltage, and

turning off the control switch element (SCR) if the potential difference between the first end and the second end of the control switch element (SCR) is smaller than the reference voltage.