Patent ID: 12254802

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring toFIG.1A, a schematic diagram of a light-emitting device driving circuit100according to an embodiment of the present disclosure is shown. The light-emitting device driving circuit100includes a current source110, a light-emitting device series120, such as a light-emitting diode series, and an input-side voltage-stabilizing circuit130. The current source110is an AC power source. The light-emitting device series120is formed of several light-emitting devices (diodes) electrically connected in series. In some embodiments, the light-emitting device series120can be realized by a high-voltage light-emitting device formed of monolithic light-emitting units electrically connected in series. The input-side voltage-stabilizing circuit130is electrically connected between the current source110and the light-emitting device series120to stabilize a driving current11. In the embodiment ofFIG.1A, the input-side voltage-stabilizing circuit130is provided with a current stabilizing function, which prevents the light-emitting device series120from frequency flickering. In an embodiment, the light-emitting device driving circuit100may include an output-side voltage-stabilizing circuit140. The output-side voltage-stabilizing circuit140is electrically connected to the light-emitting device series120to increase the power factor (PF value) of the light-emitting device driving circuit100or adjust the brightness.

In an embodiment, the input-side voltage-stabilizing circuit130may include a normally-on transistor T1, a resistor R1and a compensation capacitor C1. The normally-on transistor T1includes a D-mode FET, such as a silicone based metal oxide semiconductor field effect transistor (Si-MOSFET) or a gallium nitride based high electron mobility transistor (GaN-HEMT). The normally-on transistor T1is electrically connected to the current source110. The resistor R1is electrically connected to the normally-on transistor T1. The normally-on transistor T1, the resistor R1and the light-emitting device series120are sequentially connected in series. A gate g1of the normally-on transistor T1is electrically connected to an input end of the light-emitting device series120.

In an embodiment, the input-side voltage-stabilizing circuit130may include a resistor R4. The resistor R4and the compensation capacitor C1are electrically connected to the normally-on transistor T1and the light-emitting device series120. The resistor R4and the compensation capacitor C1are electrically connected in parallel with a drain d1of the normally-on transistor T1and an output end of the light-emitting device series120.

The light-emitting device series120has a fixed driving current11. Referring toFIG.1B, a schematic diagram of a voltage curve CV1of an input voltage providing by the current source110and a current curve CV2of the driving current11of the light-emitting device series120ofFIG.1Ais shown. The current source110provides an input current corresponding to the input voltage. The normally-on transistor T1can inhibit the input current under the high-level part P2of the current source110from a higher current to the driving current11. The compensation capacitor C1can compensate the input current under the low-level parts P1and P3of the current source110from a lower current to the driving current11. Thus, the driving current11inputted to the light-emitting device series120can maintain at the same level.

The output-side voltage-stabilizing circuit140is electrically connected to an output end of the light-emitting device series120. The output-side voltage-stabilizing circuit140includes a normally-on transistor T6, a resistor R6and an NPN transistor T7. The NPN transistor T7is configured to adjust the brightness of the light-emitting device series120. The normally-on transistor T6can also inhibit the high-level part P2of the current source110.

In other embodiments, the output-side voltage-stabilizing circuit140may not include the NPN transistor T7, which is normally-off.

Referring toFIG.2, a schematic diagram of a light-emitting device driving circuit200according to another embodiment of the present disclosure is shown. The light-emitting device driving circuit200ofFIG.2is similar to the light-emitting device driving circuit100, and the similarities are not repeated here. An input-side voltage-stabilizing circuit230of the light-emitting device driving circuit200further includes a resistor R2, a resistor R3and a PNP transistor T2. The resistor R2is electrically connected to the current source110. The resistor R3is electrically connected to the resistor R2. An emitter e2of the PNP transistor T2is electrically connected to the resistor R1, a collector c2of the PNP transistor T2is electrically connected to the light-emitting device series120, and a gate g2of the PNP transistor T2is electrically connected to a node n3between the resistor R2and the resistor R3. The resistor R3is electrically connected to the collector c2of the PNP transistor T2.

In the present embodiment, the voltage divider circuit including the resistor R2, the resistor R3and the PNP transistor T2can stabilize the power. When the voltage of the current source110is large, the node n3has a higher voltage, and the PNP transistor T2produces a larger resistance, so that the driving current11is decreased to maintain the power at certain Watt-range. Thus, in addition to the current stabilizing function, the input-side voltage-stabilizing circuit230can further provide a power stabilizing function.

Referring toFIG.3, a schematic diagram of a light-emitting device driving circuit200′ according to another embodiment of the present disclosure is shown. A difference between the light-emitting device driving circuit200′ and the light-emitting device driving circuit200ofFIG.2is that the resistor R3of the input-side voltage-stabilizing circuit230′ is grounded. The input-side voltage-stabilizing circuit230′ can implement the power stabilizing function whether the resistor R3is grounded or electrically connected to a reference voltage.

Referring toFIG.4, a schematic diagram of a light-emitting device driving circuit300according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit300and the light-emitting device driving circuit200ofFIG.2is that the output-side voltage-stabilizing circuit340does not include an NPN transistor T7. Although the light-emitting device driving circuit300is not provided with an NPN transistor T7, the input-side voltage-stabilizing circuit330still can implement the current stabilizing and power stabilizing functions.

Referring toFIG.5, a schematic diagram of a light-emitting device driving circuit300′ according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit300′ and the light-emitting device driving circuit200′ ofFIG.3is that the output-side voltage-stabilizing circuit340is not provided with an NPN transistor T7. Although the light-emitting device driving circuit300′ is not provided with the NPN transistor T7, the input-side voltage-stabilizing circuit330′ still can implement the current stabilizing and power stabilizing functions.

Referring toFIG.6, a schematic diagram of a light-emitting device driving circuit400according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit400and the light-emitting device driving circuit200′ ofFIG.3is that the light-emitting device driving circuit400includes two light-emitting device series421and422and two output-side voltage-stabilizing circuits441and442electrically connected to the light-emitting device series421and422, respectively. Moreover, the resistor R4and one end of the compensation capacitor C1are grounded. The light-emitting device series421and422are electrically connected in parallel. In an embodiment, the light-emitting device series421and422can emit different colors of light, such as white light and yellow light. The light-emitting device series421and the light-emitting device series422can be turned on concurrently or separately. With the light-emitting device series421and the light-emitting device series422being turned on concurrently or separately, the color of a mixing light from the lights of the light-emitting device series421and the light-emitting device series422can be adjusted. In one embodiment, the light-emitting device series421and422emit a white light and a yellow light respectively. When the light-emitting device series421is turned on and the light-emitting device series422is turned off, the mixing light is emitted from the light-emitting device series421which is a white light. When the light-emitting device series422is turned on and the light-emitting device series421is turned off, the mixing light is emitted from the light-emitting device series422which is a yellow light. When the light-emitting device series421and the light-emitting device series422are concurrently turned on, the mixing light is a mixture of white light and yellow light emitted by the light-emitting device series421and the light-emitting device series422, and which is a warm white light. That is, the color temperature of the white light can be adjusted. The light-emitting device series421and422share the same input-side voltage-stabilizing circuit430.

The output-side voltage-stabilizing circuit441is electrically connected to an output end of the light-emitting device series421; the output-side voltage-stabilizing circuit442is electrically connected to an output end of the light-emitting device series422. Similar to the output-side voltage-stabilizing circuit140ofFIG.1A, the output-side voltage-stabilizing circuit441includes an NPN transistor T7configured to adjust the brightness of the light-emitting device series421. Similar to the output-side voltage-stabilizing circuit140ofFIG.1A, the output-side voltage-stabilizing circuit442includes an NPN transistor T7configured to adjust the brightness of the light-emitting device series422.

In the light-emitting device driving circuit400, the number of the light-emitting device series is not limited to two, and it can be more than two. The number of the output-side voltage-stabilizing circuit441is corresponded to the number of the light-emitting device series. In additional to the embodiment ofFIG.6, the number of light-emitting device series of each of the embodiments mentioned above can be more than 2, and the number of output-side voltage-stabilizing circuit can also be more than 2.

Referring toFIG.7, a schematic diagram of a light-emitting device driving circuit500according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit500and the light-emitting device driving circuit100ofFIG.1Ais that the input-side voltage-stabilizing circuit530of the light-emitting device driving circuit500further includes a resistor R2, and the light-emitting device driving circuit500does not include the output-side voltage-stabilizing circuit140. The resistor R2is electrically connected between the resistor R1and the output end of the light-emitting device series120. The gate g1of the normally-on transistor T1is electrically connected to a node n4between the resistor R1and the resistor R2. The input end of the light-emitting device series120is electrically connected to a source s1of the normally-on transistor T1. The output end of the light-emitting device series120is grounded.

The normally-on transistor T1can inhibit the input current under the high-level part P2(illustrated inFIG.1B) of the current source110from a higher current to the driving current11. The compensation capacitor C1can compensate the input current under the low-level parts P1and P3(illustrated inFIG.1B) of the current source110from a lower current to the driving current11. The normally-on transistor T1and the compensation capacitor C1can stabilize the current. The voltage divider circuit formed of the resistor R1and the resistor R2can stabilize the power. Thus, the input-side voltage-stabilizing circuit530is provided with both the current stabilizing function and the power stabilizing function.

Referring to Table 1, changes in the power of the light-emitting device driving circuit500when the current source110is at different voltages are illustrated. As illustrated in Table 1, when the current source110is at different voltages, the power of the light-emitting device driving circuit500may be maintained between 5.28 W and 5.34 W, to achieve the power stabilizing result.

TABLE 1Current sourceInputTotal harmonic110 (alternatingPowercurrentPowercurrentcurrent)(W)(mA)factordistortion220 V-50 Hz5.3445.50.532148.12230 V-50 Hz5.3144.20.521153.3240 V-50 Hz5.3443.420.51158.4250 V-50 Hz5.3142.20.5163.2260 V-50 Hz5.28410.491168

Referring toFIG.8, a schematic diagram of a light-emitting device driving circuit600according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit600and the light-emitting device driving circuit500ofFIG.7is that the light-emitting device driving circuit600further includes an output-side voltage-stabilizing circuit640. The output-side voltage-stabilizing circuit640is configured to increase the power factor (PF value) and adjust the brightness. The NPN transistor T7is configured to adjust the brightness of the light-emitting device series120. In the output-side voltage-stabilizing circuit640, the normally-on transistor T6can also inhibit the high-level part P2(illustrated inFIG.1B) of the current source110.

In other embodiments, the output-side voltage-stabilizing circuit640does not include the normally-off transistor T7.

Referring to Table 2, changes in the power of the light-emitting device driving circuit600when the current source110is at different voltages are illustrated. As illustrated in Table 2, when the current source110is at different voltages, the power of the light-emitting device driving circuit600can be maintained between 6.25 and 6.6 w to achieve the power stabilizing result.

TABLE 2Current sourceInputTotal harmonic110 (alternatingPowercurrentPowercurrentcurrent)(w)(mA)factordistortion220 V-50 Hz6.2540.90.793.5230 V-50 Hz6.640.80.793.5240 V-50 Hz6.4439.60.67100.5250 V-50 Hz6.3438.50.65105.2260 V-50 Hz6.3137.60.63109

Referring toFIG.9A, a schematic diagram of a light-emitting device driving circuit700according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit700and the light-emitting device driving circuit500ofFIG.7is that the light-emitting device driving circuit700is provided with a multi-stage lighting design. The light-emitting device driving circuit700includes several input-side voltage-stabilizing circuits, and several light-emitting device series corresponding to the several input-side voltage-stabilizing circuits. The input-side voltage-stabilizing circuits are electrically connected between the current source110and the light-emitting device series. In one embodiment, the light-emitting device driving circuit700includes a four-stage lighting design. The light-emitting device driving circuit700includes four input-side voltage-stabilizing circuits731,732,733, and734and four light-emitting device series721,722,723, and724. The input-side voltage-stabilizing circuit731is electrically connected between the current source110and the light-emitting device series721, the input-side voltage-stabilizing circuit732is electrically connected between the current source110and the light-emitting device series722, the input-side voltage-stabilizing circuit733is electrically connected between the current source110and the light-emitting device series723, and the input-side voltage-stabilizing circuit734is electrically connected between the current source110and the light-emitting device series724.

The output end of the light-emitting device series721is grounded. The input end of the light-emitting device series721is electrically connected to the output end of the light-emitting device series722; the input end of the light-emitting device series722is electrically connected to the output end of the light-emitting device series723; the input end of the light-emitting device series723is electrically connected to the output end of the light-emitting device series724.

Each of the input-side voltage-stabilizing circuits731,732, and733includes a PNP transistor T3and a Zener diode Z1. The PNP transistor T3is arranged between the normally-on transistor T1and the resistor R1. The Zener diode Z1is electrically connected to a gate g3of the PNP transistor T3.

The turn-on voltage of the Zener diode Z1is such as 6V. The turn-on voltage of a light-emitting device series is such as 9V.

When merely the light-emitting device series721is turned on, the current stabilizing function is performed by the input-side voltage-stabilizing circuit731.

When the light-emitting device series722is turned on, the Zener diode Z1of the input-side voltage-stabilizing circuit731will be turned on, so that the normally-on transistor T1of the input-side voltage-stabilizing circuit731is turned off. Meanwhile, the current stabilizing function changes to be performed by the input-side voltage-stabilizing circuit732.

When the light-emitting device series723is turned on, the Zener diode Z1of the input-side voltage-stabilizing circuit732will be turned on, so that the normally-on transistor T1of the input-side voltage-stabilizing circuit732is turned off. Meanwhile, the current stabilizing function changes to be performed by the input-side voltage-stabilizing circuit733.

When the light-emitting device series724is turned on, the Zener diode Z1of the input-side voltage-stabilizing circuit733will be turned on, so that the normally-on transistor T1of the input-side voltage-stabilizing circuit733is turned off. Meanwhile, the current stabilizing function changes to be performed by the input-side voltage-stabilizing circuit734.

Referring toFIG.9B, a schematic diagram of a current curve CV3of the light-emitting device driving circuit700ofFIG.9Ais shown. As the voltage of the current source110increases, the current stabilizing function gradually switches from the input-side voltage-stabilizing circuit731to the input-side voltage-stabilizing circuit734. Thus, the current curve CV3presents a stepped shape of stable current.

Besides, the input-side voltage-stabilizing circuit734also performs the power stabilizing function with the voltage divider circuit formed of the resistor R1and the resistor R2. Thus, the light-emitting device driving circuit700is provided with both the current stabilizing function and the power stabilizing function.

Referring toFIG.10, a schematic diagram of a light-emitting device driving circuit800according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit800and the light-emitting device driving circuit700ofFIG.9Ais that the light-emitting device driving circuit800further includes an output-side voltage-stabilizing circuit840and a pulse width modulation (PWM) modulation circuit850. The output-side voltage-stabilizing circuit840is electrically connected to the output end of the light-emitting device series821. The PWM modulation circuit850is electrically connected to the output-side voltage-stabilizing circuit840to adjust the brightness of the light-emitting device series821,822,823,824.

Referring toFIG.11, a schematic diagram of a light-emitting device driving circuit900according to another embodiment of the present disclosure is shown. The difference between the light-emitting device driving circuit900ofFIG.11and the light-emitting device driving circuit700ofFIG.9Ais that the light-emitting device driving circuit900further includes a bleeder circuit960. The bleeder circuit960is electrically connected to the current source110to adjust the brightness of the light-emitting device series921,922,923,924.

According to the above embodiments, the light-emitting device driving circuit provides a current stabilizing function through the circuit design of the normally-on transistor, the resistor and the compensation capacitor of an input-side voltage-stabilizing circuit to achieve the flickering free result. Besides, the light-emitting device driving circuit can also provide a power stabilizing function through the circuit design of a voltage divider circuit.

While the invention has been described by way of example and in terms of the preferred embodiment(s), it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.