JP6542604B2 - LED lamp - Google Patents

Description

  The present invention relates to an LED lamp.

  In recent years, lamps using LEDs (hereinafter referred to as “LED lamps”) have come to be used as light sources for illumination because of low power consumption and long life. . In particular, for example, in the field of spotlight light sources for 12 V, replacement (retrofit) from a halogen lamp to an LED lamp is in progress (see, for example, Patent Document 1).

Patent No. 5647250 gazette

  In order to realize retrofit from a halogen lamp to an LED lamp, it is desirable from the viewpoint of resource saving that it is preferable to be able to light the LED lamp as much as possible utilizing equipment used for the halogen lamp as much as possible. For example, in the light source field for 12 V, after the commercial voltage is converted to a low voltage by the electronic transformer, this voltage is supplied to the halogen lamp. Therefore, if it is possible to supply the LED lamp using the AC voltage supplied from the electronic transformer, it is efficient because there is no need to separately provide a voltage conversion unit.

  Patent Document 1 discloses a technique for solving the problem that flicker occurs during driving when the above-described retrofit is realized.

  By the way, when replacing the halogen lamp with the LED lamp, it is assumed that the replacing operation is performed with the AC voltage supplied to the primary side of the electronic transformer. For example, it is conceivable that the lamp is replaced in the procedure of removing the socket of the halogen lamp with the main switch turned on and mounting the socket of the LED lamp. This is because if all the lights are turned off once the main switch is turned off, it becomes dark and work efficiency declines, and it is bothersome to turn off the main switch every time. It is.

  According to the intensive studies of the present inventors, when the work of replacing the halogen lamp with the LED lamp is performed while the main switch is turned on as described above, the LED lamp may not be lit. I understood. The present invention has been made to solve such problems.

The LED lamp according to the present invention is
An AC / DC conversion unit connected to a terminal on the secondary side of the electronic transformer to convert an input AC voltage into a DC voltage;
An LED driver to which a DC voltage output from the AC / DC conversion unit is input;
An LED element driven by the LED driver;
And a non-lighting prevention circuit connected in parallel with the load on the LED element side at a position between the terminal on the secondary side of the electronic transformer and the LED driver,
The non-lighting prevention circuit is a circuit having an impedance lower than the impedance of the load on the side of the LED element before the start of lighting of the LED element, and higher than the impedance of the load on the side of the LED element at the time of lighting the LED element. It is characterized by

  The inventors of the present invention have intensively studied to find that the cause of the failure when replacing the halogen lamp with the LED lamp is that the condition of the minimum load current is imposed on the electronic transformer.

  FIG. 1 is a view showing an example of the configuration of the electronic transformer. The electronic transformer 60 shown in FIG. 1 includes a rectification circuit 61, a smoothing circuit 62, and an oscillation circuit 63. Commercial alternating current voltage is input to the primary side terminal 60 a of the electronic transformer 60. The rectifier circuit 61 converts this commercial AC voltage into a DC voltage. The DC voltage is smoothed by a smoothing circuit 62 including, for example, a capacitor C62, and then input to an oscillation circuit 63.

  The oscillation circuit 63 includes a transformer Tr63 having a primary winding LL1, a secondary winding LL2, and a tertiary winding LL3, a switching element Q63, a resistor R63, and a diode D63. The switching element Q63 performs switching to apply a voltage to the primary winding LL1 of the transformer Tr63, thereby generating an induced voltage in the secondary winding LL2 and the tertiary winding LL3. The voltage generated in the tertiary winding LL3 is positively fed back to the switching element Q63. Thereby, the oscillation circuit 63 repeats self-excitation oscillation operation, and the switching element Q63 repeats switching operation. As an example, when an alternating voltage with a frequency of 50/60 Hz and 100 V is applied to the primary side terminal 60a of the electronic transformer 60, an alternating voltage with a frequency of 20 kHz to 100 kHz and 12 V is induced in the secondary winding LL2 of the transformer Tr63. This voltage is taken out from the secondary side terminal 60 b of the electronic transformer 60.

  The electronic transformer 60 is provided for the purpose of reducing the commercial voltage when lighting the lamp at a voltage lower than the commercial voltage. However, the electronic transformer 60 is designed such that stable oscillation can not be performed unless a current of a certain level or more (hereinafter referred to as "minimum load current") flows from the secondary side terminal 60b to the load. It has limitations.

  Furthermore, the LED is a non-linear element in which no current flows in a low voltage region until the driver starts operating. FIG. 2 is a diagram schematically showing current-voltage characteristics of the LED element and the halogen lamp. As shown in FIG. 2, in the halogen lamp, current flows according to the applied voltage, but in the LED element, no current or almost no current flows within the range below the predetermined threshold voltage Vth.

  This fact is the reason for the occurrence of the situation where the LED lamp does not light when the operation of replacing the halogen lamp with the LED lamp is performed while the electronic transformer 60 is in operation. Since a halogen lamp can be considered to be a resistive element having linearity, even when a low voltage is applied, a low current flows according to the applied voltage. Therefore, a voltage can be continuously induced in secondary winding LL2, and switching element Q63 can also be oscillated stably.

  A case is considered in which the halogen lamp is removed and the LED lamp including the LED element is connected to the secondary side terminal 60b of the electronic transformer 60 while the halogen lamp is on. When the halogen lamp is removed, the secondary side terminal 60b of the electronic transformer 60 is in the open state, which is equivalent to the connection of a very large impedance. As a result, almost no current flows from the secondary winding LL2 of the electronic transformer 60 to the load side, so the current from the secondary winding LL2 of the electronic transformer 60 toward the load side is the minimum load current of the electronic transformer 60 And the electronic transformer 60 does not oscillate stably. That is, no voltage or almost no voltage is induced in the secondary winding LL2 of the electronic transformer 60.

  In this state, an LED lamp including an LED element is connected to the secondary side terminal 60 b of the electronic transformer 60. Since no voltage or almost no voltage is induced in the secondary winding LL2 of the electronic transformer 60, the voltage applied to the LED element is lower than the threshold voltage Vth. As a result, no current flows in the LED element. Therefore, a state in which almost no current flows from the secondary winding LL2 of the electronic transformer 60 to the load side is continued. That is, since the current from the secondary winding LL2 of the electronic transformer 60 toward the load side still falls below the minimum load current of the electronic transformer 60, the environment continues to cause the electronic transformer 60 to stably oscillate.

  As a result, when the lighted halogen lamp is removed and the LED lamp is attached, a state occurs in which the LED lamp does not light.

  The LED lamp according to the present invention includes the non-lighting prevention circuit connected in parallel with the load on the LED element side between the terminal on the secondary side of the electronic transformer and the LED driver. Here, the load on the LED element side refers to a load (for example, a series circuit including an LED driver and an LED element) connected to the LED element side as viewed from the non-lighting prevention circuit.

  The non-lighting prevention circuit has an impedance lower than the impedance of the load on the LED element side before the start of lighting of the LED element, and higher than the impedance of the load on the LED element side when the LED element is lit.

  That is, the impedance of the non-lighting prevention circuit is higher than the impedance on the LED element side than the non-lighting prevention circuit including the LED element and the LED driver when a voltage equal to or lower than the threshold voltage is applied to the LED element. As shown in FIG. 2, the LED element is a non-linear element, and the impedance of the LED element when the voltage equal to or lower than the threshold voltage is applied to the LED element exhibits extremely high impedance.

  Also, the impedance of the non-lighting prevention circuit includes the LED element and the LED driver when the LED element is lit, that is, when a voltage higher than the threshold voltage is applied to the LED element. It is lower than the impedance on the LED element side.

  According to this configuration, immediately after the halogen lamp is removed and the LED lamp is attached, the LED element included in the LED lamp is in the state before lighting, and thus exhibits extremely high impedance as described above. A non-lighting prevention circuit whose impedance is lower than the load impedance including the LED element before lighting is connected in parallel with the load on the LED element side at a position between the terminal on the secondary side of the electronic transformer and the LED driver . Therefore, when the LED lamp is connected to the secondary side terminal of the electronic transformer, the current in the closed circuit returns from the secondary side terminal of the electronic transformer to the secondary side terminal of the electronic transformer via the non-lighting prevention circuit. Flows. As a result, a current exceeding the minimum load current of the electronic transformer flows, and a voltage is induced at the secondary side terminal of the electronic transformer.

  Then, if the induced voltage exceeds the threshold voltage of the LED element, the impedance of the non-lighting prevention circuit is higher than the load impedance on the LED element side when the LED element is lit, so from the secondary side terminal of the electronic transformer Compared to the non-lighting prevention circuit, more current flows to the load on the LED element side. Thereby, the LED element is lit. When current flows in the LED element, a current exceeding the minimum load current of the electronic transformer continuously flows, and a voltage is stably induced in the secondary side terminal of the electronic transformer.

  The non-lighting prevention circuit can be configured to include a resistor.

  The non-lighting prevention circuit can be configured to include a capacitor connected in parallel to the resistor. According to this configuration, it is possible to reduce the amount of current flowing to the non-lighting prevention circuit at the time of lighting the LED and to reduce the power consumption as compared with the case where the non-lighting prevention circuit is configured only by the resistor.

  The non-lighting prevention circuit may further include a diode connected in series with the resistor.

  When the non-lighting prevention circuit is disposed closer to the electronic transformer than the rectifier circuit, an alternating voltage is applied to the non-lighting prevention circuit. For this reason, when the non-lighting prevention circuit is configured by a parallel RC circuit, since it has an impedance of Z = R / (1 + jωRC), current always flows in the non-lighting prevention circuit at the time of lighting. On the other hand, by connecting diodes in series, current flows until the capacitor is charged, but when discharged from the capacitor, it is not conducted by the diode, so the current flows within the non-lighting prevention circuit. It can be limited. As a result, the amount of current flowing through the non-lighting prevention circuit can be further reduced when the LED is lighted.

  The non-lighting prevention circuit may be disposed between a terminal on the secondary side of the electronic transformer and the AC / DC conversion unit, and may be connected in parallel to the AC / DC conversion unit.

  When the non-lighting prevention circuit is disposed closer to the LED element than the AC / DC conversion unit, the DC voltage obtained by the AC / DC conversion unit converting the alternating voltage induced on the secondary side terminal of the electronic transformer Is applied to the non-lighting prevention circuit. During the voltage conversion in the AC / DC converter, the voltage drops. As a result, in order to generate a voltage higher than the threshold voltage of the LED element across the non-lighting prevention circuit, compared to the case where the non-lighting prevention circuit is disposed closer to the electronic transformer than the AC / DC conversion unit, Larger voltages will be required.

  As described above, by arranging the non-lighting prevention circuit closer to the electronic transformer than the AC / DC conversion unit, the LED lamp can be turned on earlier and more reliably when replacing the halogen lamp with the LED lamp. it can.

The non-lighting prevention circuit
A first circuit comprising a first resistor, a first capacitor connected in parallel to the first resistor, and a first diode connected in series to the first resistor;
A second resistor, a second capacitor connected in parallel to the second resistor, and a second diode connected in series to the second resistor and having a direction opposite to that of the first diode; It may be a circuit including a second circuit connected in parallel to the circuit.

  When an AC voltage is supplied to the non-lighting prevention circuit, the above configuration can suppress the amount of current flowing in the non-lighting prevention circuit at the time of LED lighting even if the polarity of the voltage is reversed. Power can be reduced.

  According to the LED lamp of the present invention, even when installed in place of the halogen lamp, it can be turned on more reliably than before.

It is a figure which shows an example of a structure of an electronic transformer. It is the figure which showed the current voltage characteristic of a LED element and a halogen lamp typically. It is a block diagram showing composition of a LED lamp of one embodiment typically. It is a block diagram which shows the structure of the LED lamp of another embodiment typically. It is a block diagram which shows the structure of the LED lamp of another embodiment typically. It is a block diagram which shows the structure of the LED lamp of another embodiment typically. It is a block diagram which shows the structure of the LED lamp of another embodiment typically.

  One embodiment of the LED lamp of the present invention will be described with reference to the drawings. The same reference numerals as in FIG. 1 denote the same elements as in FIG.

  FIG. 3 is a block diagram schematically showing the configuration of the LED lamp according to one embodiment. The LED lamp 1 shown in FIG. 3 includes an AC / DC conversion unit 20 connected to the secondary side terminal 60b of the electronic transformer 60, and an LED driver 30 disposed downstream of the AC / DC conversion unit 20. And an LED element 40 which is supplied with a direct current from the LED driver 30 to perform drive control. The LED lamp 1 further includes a non-lighting prevention circuit 10 connected in parallel to the AC / DC conversion unit 20 at a position between the electronic transformer 60 and the AC / DC conversion unit 20.

  In the present embodiment, the non-lighting prevention circuit 10 includes a first circuit 11 and a second circuit 12. The first circuit 11 includes a resistor R11, a capacitor C11 connected in parallel to the resistor R11, and a diode D11 connected in series to the resistor R11. The second circuit 12 is connected in parallel to the first circuit 11, and is connected in series to a resistor R12, a capacitor C12 connected in parallel to the resistor R12, and a resistor R12, and a diode whose conduction direction is reversed to that of the diode D11. And D12.

  As described above, the LED element 40 hardly flows current while a voltage equal to or lower than the threshold voltage Vth is applied, and conducts light when a voltage exceeding the threshold voltage Vth is applied. That is, the LED element 40 has a very high impedance in the state before the start of lighting, and has the property that the impedance is reduced at the time of lighting. Both the first circuit 11 and the second circuit 12 have lower load impedances on the LED element 40 side than the non-lighting prevention circuit 10 before the lighting start of the LED element 40, and The values of the respective circuit elements are adjusted such that the impedance is higher than the load impedance on the LED element 40 side than the non-lighting prevention circuit 10. Since the impedance of the LED element 40 is extremely high before the start of lighting of the LED element 40, the load impedance on the LED element 40 side relative to the non-lighting prevention circuit 10 substantially depends on the impedance of the LED element 40.

  The AC / DC conversion unit 20 is configured of, for example, a rectification diode that constitutes a full wave rectification circuit. The LED driver 30 is a driver for driving the LED 40, and is realized by a known technique.

  The electronic transformer 60 may be a transformer that constitutes a voltage source of a halogen lamp. That is, after the secondary side terminal 60b of the electronic transformer 60, the halogen lamp and its drive circuit are configured, and it is removed to prevent the non-lighting prevention circuit 10, the AC / DC conversion unit 20, the LED driver 30, and A module including the LED element 40 may be attached. For example, this module is integrated and connected to the secondary side terminal 60b of the electronic transformer 60 by a screw (screw) or a pin provided on a ceiling surface or the like.

  A case where the module is attached while the voltage is supplied to the primary side terminal 60a of the electronic transformer 60 will be examined. At this time, since the LED element 40 is in the state before lighting, it exhibits extremely high impedance. Therefore, since the load impedance formed by the series circuit including the AC / DC conversion unit 20, the LED driver 30, and the LED element 40 is large from the secondary side terminal 60b of the electronic transformer 60, almost current flows in the series circuit. Absent. On the other hand, since the non-lighting prevention circuit 10 connected in parallel with this series circuit has a lower impedance than that of the series circuit, a certain amount of current flows from the secondary side terminal 60b of the electronic transformer 60 to the non-lighting prevention circuit 10 Flows. As a result, a current exceeding the minimum load current of the electronic transformer 60 flows, and a voltage is stably induced in the secondary side terminal 60b.

  When the induced voltage of the secondary side terminal 60 b exceeds a certain value, the voltage applied to the LED element 40 exceeds the threshold voltage Vth of the LED element 40. At this time, current starts to flow to the LED element 40, and the LED element 40 is lit. Thereafter, the impedance of the LED element 40 is lowered, so that the load impedance of the series circuit including the AC / DC converter 20, the LED driver 30, and the LED element 40 is lower than the impedance of the non-lighting prevention circuit 10. As a result, the amount of current flowing from the secondary side terminal 60b of the electronic transformer 60 toward the non-lighting prevention circuit 10 decreases, and current continuously flows to the LED element 40 side. Thereby, the LED element 40 emits light stably.

  As an example, the impedance before the lighting start of the LED element 40 is 14 kΩ, the impedance at the lighting time of the LED element 40 is 17 Ω, and the resistors R11 and R12 included in the non-lighting prevention circuit 10 are 1 kΩ.

  Hereinafter, only the first circuit 11 of the non-lighting prevention circuit 10 will be described because the description is duplicated. The non-lighting prevention circuit 10 includes the capacitor C11 connected in parallel with the resistor R11, so that after the LED element 40 is lit, after the capacitor C11 is charged, the resistor R11 is compared to the case where the capacitor C11 is not provided. The amount of current flowing to the As a result, the generation of power consumption in the non-lighting prevention circuit 10 when the LED element 40 is lighted is suppressed.

  In addition, when the non-lighting circuit circuit 10 includes the diode D11 connected in series with the resistor R11, charges accumulated in the capacitor C11 flow out and power is consumed, as compared to the case where the diode D11 is not provided. Are suppressed. In particular, in the present embodiment, since the non-lighting prevention circuit 10 is disposed closer to the electronic transformer 60 than the AC / DC conversion unit 20, an alternating voltage is supplied to the non-lighting prevention circuit 10. As shown in FIG. 3, when the non-lighting prevention circuit 10 includes the two diodes D11 and D12 having different conduction directions, generation of power consumption can be suppressed regardless of the polarity of the voltage.

[Another embodiment]
Another embodiment will be described below.

  As shown in FIG. 4, the non-lighting prevention circuit 10 may be configured to include only the first circuit 11. Also in this case, the probability that the LED lamp 1 is not lit can be lowered when replacing the halogen lamp with the LED lamp 1 as compared with the conventional configuration.

  Further, as shown in FIG. 5, the non-lighting prevention circuit 10 may be configured without the diode D11 in the configuration of FIG. In the configuration of FIG. 3, the non-lighting prevention circuit 10 may be configured not to include the diodes D11 and D12.

  Furthermore, as shown in FIG. 6, the non-lighting prevention circuit 10 may be configured not to include the diode D11 and the capacitor C11 in the configuration of FIG. In the configuration of FIG. 3, the non-lighting prevention circuit 10 may be configured not to include the diodes D11 and D12 and the capacitors C11 and C12.

  Although the power consumption in the non-lighting prevention circuit 10 at the time of lighting of the LED element 40 is increased in the case of the configuration of FIG. 5 and FIG. 6 compared to the configuration of FIG. It is possible to reduce the probability that the lamp will not light.

  Further, as shown in FIG. 7, the non-lighting prevention circuit 10 may be disposed between the AC / DC conversion unit 20 and the LED driver 30. However, in this case, the voltage applied to the non-lighting prevention circuit 10 is a voltage obtained by subtracting the voltage drop at the AC / DC conversion unit 20 from the voltage induced at the secondary side terminal 60b of the electronic transformer 60. Become. For this reason, the induced voltage of the secondary side terminal 60b required for conducting the LED element 40 becomes higher than the configuration of FIG. As a result, compared to the configuration of FIG. 3, the time required for the LED element 40 to start light emission may increase. However, even with this configuration, compared to the conventional configuration, the probability that the LED element 40 is not lit can be reduced.

  When the non-lighting prevention circuit 10 is configured as shown in FIGS. 4 to 6, the non-lighting prevention circuit 10 may be disposed between the AC / DC conversion unit 20 and the LED driver 30.

1: LED lamp
10: Non-lighting prevention circuit
11: First circuit
12: Second circuit
20: AC / DC converter
30: LED driver
40: LED element
60: Electronic transformer
60a: Primary terminal of electronic transformer
60b: Secondary terminal of electronic transformer
61: Rectifier circuit
62: Smoothing circuit
63: Oscillator circuit
C11, C12, C62: Capacitors
D11, D12, D63: Diodes
LL1, LL2, LL3: Windings
R11, R12, R63: Resistance
Tr63: Transformer
Q63: Switching element

Claims (2)

An AC / DC conversion unit connected to the secondary side terminal of the electronic transformer to convert an input AC voltage into a DC voltage;
An LED driver to which a DC voltage output from the AC / DC conversion unit is input;
An LED element driven by the LED driver;
And a non-lighting prevention circuit connected in parallel with the load on the LED element side at a position between the terminal on the secondary side of the electronic transformer and the LED driver,
The unlighted prevention circuit, wherein before the start of lighting of the LED elements lower than the impedance of the load of the LED element side, a circuit having a high impedance than the impedance of the load of the LED element side at the time of lighting of the LED element ,
The non-lighting prevention circuit is disposed between a terminal on the secondary side of the electronic transformer and the AC / DC conversion unit, and is connected in parallel to the AC / DC conversion unit.
The non-lighting prevention circuit
A first circuit comprising a first resistor, a first capacitor connected in parallel to the first resistor, and a first diode connected in series to the first resistor;
A second resistor, a second capacitor connected in parallel to the second resistor, and a second diode connected in series to the second resistor and reverse in conduction direction to the first diode, the first circuit And a second circuit connected in parallel to the LED lamp. The first resistor is connected to the cathode of the first diode,
The LED lamp according to claim 1, wherein the second resistor is connected to a cathode of the second diode.

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