TWI416453B - Illuminating apparatus and light source control circuit thereof - Google Patents

Abstract

A light source control circuit for controlling N light emitted diodes (LEDs) coupled in serial is provided, and includes a current supply unit, a current collection unit and N switch units, wherein N is positive integer. The current supply unit provides N reference currents. The current collection unit provides a collection current, and adjusts the collection current according to a level of a control voltage. Each of the switch units has a transmission path and a current path, wherein the ith switch unit turns on the transmission path or the current path thereof according to the collection current, so that the ith reference current is transmitted to the current collection unit or the ith LED can't generate light source, wherein i is an integer and 1 ≤ i ≤ N.

Description

Lighting device and its light source control circuit

The present invention relates to an illumination device and a light source control circuit thereof, and more particularly to an illumination device for a light-emitting diode and a light source control circuit thereof.

Light Emitting Diode (LED) has advantages such as long life, small size, high shock resistance, low heat generation and low power consumption, and thus has been widely used as an indicator or a light source in households and various devices. In recent years, light-emitting diodes have developed toward multiple colors and high brightness, so their application fields have expanded to large outdoor billboards, traffic lights and related fields. In the future, light-emitting diodes may even become the main source of illumination for both power saving and environmental protection functions.

In general, most of the control circuits of the light-emitting diodes convert the alternating voltage into a direct current voltage or current, and then use a stable direct current voltage or current to control the brightness of the light source of the light-emitting diode. In other words, the control circuit of the conventional light-emitting diode is usually embedded with an AC-DC converter, or it must be matched with a transformer to be controlled by the AC power supply. However, the lines of the above control circuit are too complicated and increase the cost when applied to a large voltage range. In addition, the brightness of the light source of the light-emitting diode can also be controlled by means of a series resistor, but the energy efficiency of this control method is too poor.

The invention provides a light source control circuit for simultaneously controlling the state of a plurality of switching units by using a current collecting unit, thereby reducing the complexity of the control circuit.

The present invention provides a lighting device that utilizes a light source control circuit to enhance the overall performance of the circuit.

The invention provides a light source control circuit for controlling N light emitting diodes connected in series, N is a positive integer, and the light source control circuit comprises a current supply unit, a current collecting unit and N switching units. The current supply unit provides N reference currents. The current collecting unit provides a collecting current and adjusts the magnitude of the collecting current according to the level of the control voltage. Each of the N switching units has a transmission path and a current path, wherein the i-th switching unit is connected in parallel with the ith LED through the transmission path and transmits the current path and the remaining switching. The units are connected in series. In addition, the i-th switching unit turns on the current path or the transmission path of the i-th switching unit to transmit the ith reference current to the current collecting unit or the ith LED cannot be used. A light source is generated, i is an integer and 1≦i≦N.

In an embodiment of the invention, the transmission paths of the N switching units are sequentially turned off as the current is increased, so that the light-emitting diodes generate light sources one by one. In addition, the current paths of the N switching units described above are sequentially turned on as the collecting current increases, so that the N reference currents are respectively guided to the current collecting unit.

In an embodiment of the invention, the ith switching unit includes a first N-type transistor, a first voltage drop device, a second N-type transistor, and a second voltage drop device. The first end of the first N-type transistor is electrically connected to the anode end of the i-th LED, and the source of the first N-type transistor is electrically connected to the cathode end of the i-th LED, the first N-type The gate of the transistor is electrically connected to the current supply unit and receives the ith reference current. The first end of the first voltage drop device is electrically connected to the gate terminal of the first N-type transistor, and the second end of the first voltage drop device is electrically connected to the source terminal of the first N-type transistor.

Furthermore, the 汲 terminal of the second N-type transistor is electrically connected to the gate terminal of the first N-type transistor, and the gate terminal of the second N-type transistor is electrically connected to the source terminal of the first N-type transistor. The first end of the second voltage drop device is electrically connected to the gate terminal of the second N-type transistor, and the second end of the second voltage drop device is electrically connected to the source terminal of the second N-type transistor. In addition, the i-th switching unit is connected to the remaining switching units in series through the gate terminal of the first N-type transistor and the source terminal of the second N-type transistor.

From another point of view, the present invention provides an illumination device comprising N first light emitting diodes and the above light source control circuit, N being a positive integer. The N first light emitting diodes are connected in series between a power supply voltage and a ground. In addition, a light source control circuit is used to control the N first light emitting diodes.

Based on the above, the light source control circuit of the present invention is a state in which a plurality of switching units are simultaneously manipulated by the current collecting unit. Thereby, as the collected current provided by the current collecting unit increases, the plurality of switching units will be sequentially switched, thereby causing the plurality of light emitting diodes to generate the light sources one by one. In this way, the present invention can reduce the complexity of the control circuit and at the same time take into account the overall performance of the circuit.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a circuit diagram of a lighting device in accordance with an embodiment of the present invention. Referring to FIG. 1 , the illumination device 10 includes a plurality of LEDs LD ₁₁ LD LD _1N and LD ₂₁ LD LD ₂₃ , a resistor R _D , and a light source control circuit 100. The light-emitting diodes LD ₁₁ to LD _1N , the light-emitting diodes LD ₂₁ to LD ₂₃ and the resistor R _D are connected in series between the power supply voltage V _DD and the ground. The light source control circuit 100 controls the conduction state of the light-emitting diodes LD ₁₁ to LD _1N , and thereby adjusts the number of series connection between the light-emitting diodes LD ₁₁ to LD _1N and the LD ₂₁ to the LD ₂₃ . In this way, the illumination device 10 will be permeable to the light source control circuit 100 to adjust the intensity of the light source emitted therefrom.

It is worth mentioning that, in practical applications, the light-emitting diodes LD ₁₁ ~LD _1N and LD ₂₁ ~LD ₂₃ are used to form a light-emitting diode series. In addition, those skilled in the art can control some or all of the LEDs in the LED array through the light source control circuit 100 as required by the design. For example, the light source control circuit 100 shown in FIG. 1 is a light emitting diode for controlling a portion of the LED array. However, in practical applications, the light emitting diode series may be composed only of the light emitting diodes LD ₁₁ to LD _1N . Thereby, the light source control circuit 100 at this time is used to control all of the light emitting diodes in the series of light emitting diodes.

Referring to FIG. 1 , the light source control circuit 100 is for controlling the N light emitting diodes LD ₁₁ LD LD _1N connected in series, where N is a positive integer. Furthermore, the light source control circuit 100 includes a current supply unit 110, a current collection unit 120, and N switching units 130_1~130_N. Here, the current supply unit 110 is configured to provide N reference currents I ₁ ~I _N . For example, the current supply unit 110 includes N current sources SD ₁ ~SD _N , wherein the current source SD _{1 is} used to generate a reference current I ₁ , the current source SD _{2 is} used to generate a reference current I ₂ , and so on.

The current collecting unit 120 is configured to provide a collecting current I _C , and the current collecting unit 120 adjusts the magnitude of the collecting current I _C according to the level of a control voltage V _C . For example, referring to FIG. 1, the current collecting unit 120 includes an N-type transistor M _C and a resistor R _C . The 汲 terminal of the N-type transistor M _C is connected in series with the switching units 130_1 ～ 130_N, and the gate terminal of the N-type transistor M _C receives the control voltage V _C . The first end of the resistor R _C is electrically connected to the source terminal of the N-type transistor M _C , and the second end of the resistor R _C is electrically connected to the ground. In practice, when the control voltage level V _C of the change, the N-type transistor gate M _C - terminal source voltage difference will change, thereby causing the N-type transistor current I M _C together produce different sizes _C.

The switching unit 130_1 has a transmission path P ₁₁ and a current path P ₂₁ . Further, the switching unit through the transmission path 130_1 P ₁₁ and the light emitting diode LD ₁₁ in parallel with each other, and P ₂₁ through a current path with the rest of the switching unit 130_2 ~ 130_N connected with each other. In actual operation, as the collection current I _C changes, the switching unit 130_1 turns on the transmission path P ₁₁ or the current path P ₂₁ . When the transmission path P _{11 is} turned off and the current path P _{21 is} turned on, the switching unit 130_1 turns on the light emitting diode LD ₁₁ , thereby causing the light emitting diode LD _{11 to} emit a light source. When the transmission path P _{11 is} turned on and the current path P _{21 is} turned off, the switching unit 130_1 transmits the reference current I ₁ to the current collecting unit 120.

For example, referring to FIG. 1, the switching unit 130_1 includes N-type transistors M ₁₁ and M ₂₁ , a voltage drop device 131_1, and a voltage drop device 132_1. The anode of the N-type transistor M ₁₁ is electrically connected to the anode end of the LED LD ₁₁ , and the source of the N-type transistor M ₁₁ is electrically connected to the cathode end of the LD _{1 of the} LED, and the N-type is electrically The gate terminal of the crystal M ₁₁ is electrically connected to the current supply unit 110 and receives the reference current I ₁ . A first end of voltage drop 131_1 electrically connected N-type gate terminal of the transistor M _11, and the second end of voltage drop 131_1 connected to the source terminal of the N-type transistor M _11.

The 汲 terminal of the N-type transistor M ₂₁ is electrically connected to the gate terminal of the N-type transistor M ₁₁ , and the gate terminal of the N-type transistor M ₂₁ is electrically connected to the source terminal of the N-type transistor M ₁₁ . The first end of the voltage drop device 132_1 is electrically connected to the gate terminal of the N-type transistor M ₂₁ , and the second end of the voltage drop device 132_1 is electrically connected to the source terminal of the N-type transistor M ₂₁ . Further, the source terminal of the switching unit 130_1 through N-type gate terminal of the transistor M ₁₁ and M _{21 is} an N-type transistor 130_2 ~ 130_N be connected with each other and the rest of the switching unit.

It is worth mentioning that in the present embodiment, the voltage drop device 131_1 includes Zener diodes ZD ₁₁ and ZD ₁₂ . The cathode end of the Zener diode ZD ₁₁ is electrically connected to the gate terminal of the N-type transistor M ₁₁ . In addition, the anode terminal of the Zener diode ZD ₁₂ is electrically connected to the anode terminal of the Zener diode ZD ₁₁ , and the cathode terminal of the Zener diode ZD ₁₂ is electrically connected to the source terminal of the N-type transistor M ₁₁ . Further, the voltage drop by a resistor 132_1 is configured by R _11. However, in other embodiments, the circuit architecture of the voltage drop device 132_1 is not limited thereto. For example, FIG. 2A to FIG. 2D are circuit diagrams of a voltage drop device according to another embodiment of the present invention, wherein, as shown in FIG. 2A and FIG. 2B, the voltage drop device 132_1 can be a Zener diode ZD1. The composition is composed of two Zener diodes ZD2 and ZD3 which are reversely connected. Furthermore, as shown in FIG. 2C and FIG. 2D, the voltage drop device 132_1 may be composed of a plurality of diodes D ₁₁ to D ₁₃ connected in series, or may be composed of two diode strings 210 and 220 connected in parallel with each other. The diode series 210 is formed by connecting the diodes D ₂₁ to D _{23 in} series, and the diode series 220 is formed by connecting the diodes D ₃₁ to D _{33 in} series.

With continued reference to FIG. 1, in actual operation, the N-type transistor M ₁₁ can form a transmission path P _{11 for controlling} whether the LD _{1 of the} light-emitting diode is turned on or not, and the N-type transistor M ₁₂ can be formed. The reference current I _{1 is} directed to the current path P _{21 of the} current collecting unit 120. Here, the switching unit 130_1 turns on one of the transmission path P ₁₁ and the current path P ₂₁ with reference to the magnitude of the collecting current I _C .

For example, initially, when the sink current I _{C is} approximately equal to 0, as indicated by the current direction CD ₁₁ , the reference current I ₁ is directed through the voltage drop 131_1 to the LED array. Accordingly, the voltage drop difference 131_1 generated will turn on the N-type drain terminal of the transistor M and the source terminal _11, thereby connecting the transmission path P _11. In contrast, when the transmission path P _{11 is} turned on, the anode end and the cathode end of the light-emitting diode LD ₁₁ will be short-circuited together, thereby causing the light-emitting diode LD _{11 to} fail to generate a light source. On the other hand, the N-type transistor M ₂₁ at this time is maintained in a non-conducting state, thereby turning off the current path P ₂₁ .

When the collecting current I _C gradually increases from zero to a certain rated value, as indicated by the current direction CD ₂₁ , the current I ₁ ' from the LED array is directed to the resistor R ₁₁ . Thereby, the N-type transistor M ₁₁ will remain in a non-conducting state, and the resistor R ₁₁ will turn on the N-type transistor M ₂₁ in response to the voltage difference generated by the current I ₁ '. As a result, when the transmission path P _{11 is} to be turned off, the light-emitting diode LD _{11 is} caused to generate a light source. Furthermore, the current path P ₂₁ will be turned on so that the reference current I ₁ is transmitted to the current collecting unit 120. It is to be noted that when I _C >(I ₁ +I ₁ '), the switching unit 130_1 continues to turn off the transmission path P ₁₁ and turn on the current path P ₂₁ .

Further, similarly, the switching unit 130_2 includes N-type transistors M ₁₂ and M ₂₂ , a voltage drop device 131_2, and a voltage drop device 132_2. The anode of the N-type transistor M ₁₂ is electrically connected to the anode end of the LED LD ₁₂ , and the source terminal of the N-type transistor M ₁₂ is electrically connected to the cathode end of the LD _{2 of the} LED, and the N-type is electrically The gate terminal of the crystal M ₁₂ is electrically connected to the current supply unit 110 and receives the reference current I ₂ . The first end is electrically connected to voltage drop 131_ N-type gate terminal of the transistor M _12, and the second end of voltage drop 131_ connected N-type source terminal of the transistor M _12.

The 汲 terminal of the N-type transistor M ₂₂ is electrically connected to the gate terminal of the N-type transistor M ₁₂ , and the gate terminal of the N-type transistor M ₂₂ is electrically connected to the source terminal of the N-type transistor M ₁₂ . A first terminal of the voltage drop 132_2 is connected to the N-type gate terminal of the transistor M _22, and the second end of voltage drop 132_2 connected to the source terminal of the N-type transistor M _22. Further, the switching unit 130_2 is connected in series with the remaining switching units 130_1, 130_3 to 130_N through the gate terminal of the N-type transistor M ₁₂ and the source terminal of the N-type transistor M ₂₂ . In addition, the voltage drop device 131_2 has the same circuit structure as the voltage drop device 131_1, and the voltage drop device 132_1 has the same circuit structure as the voltage drop device 132_2, and thus will not be described herein.

Referring to FIG. 1 , in actual operation, initially, when the collecting current I _{C is} approximately equal to 0, as indicated by the current direction CD ₁₂ , the reference current I ₂ is guided to the LED array through the voltage drop device 131_2. . At this time, the transmission path P _{12 is} turned on in response to the voltage difference generated by the voltage drop device 131_2, and the current path P ₂₂ at this time is maintained in a non-conducting state. When the sinking current I _{C is} gradually increased to a certain rated value, as indicated by the current direction CD ₂₂ , the current I ₂ ' from the LED array will be directed to the resistor R ₁₂ . At this time, when the transmission path P _{12 is} to be turned off, the light-emitting diode LD _{12 is} caused to generate a light source. Furthermore, current path P ₂₂ will be turned on so that reference current I ₁₂ is delivered to current sink unit 120. It is to be noted that when I _C >(I ₁ +I ₁ '+I ₂ +I ₂ '), the switching unit 130_1 continues to turn off the transmission path P ₁₁ and turn on the current path P ₂₁ .

By analogy, it can be known that, at the beginning, when the collecting current I _{C is} approximately equal to 0, the transmission paths P _11~ P _{1N of the} switching units 130_1~130_N are all in an on state, and the switching units 130_1~130_N have The current paths P _{21 to} P _{2N are} all in a non-conducting (closed) state. In other words, initially, when the collecting current I _C is small, the N-type transistors M ₁₁ -M _{1N are} all turned on, and the N-type transistors M ₂₁ -M _2N are not turned on. At this time, none of the light-emitting diodes LD ₁₁ to LD _1N controlled by the light source control circuit 100 can emit a light source.

However, when the sink current I _C gradually increases and I _C >(I ₁ +I ₁ '), the switching unit 130_1 performs switching of the transmission path P ₁₁ and the current path P ₂₁ to turn off the transmission path P ₁₁ and turn on the current path. P ₂₁ . At this time, the light emitting diode LD ₁₁ will be closed due to a transmission path P ₁₁ of the light source is generated, and the reference current I ₁ will be directed to the current sink unit 120. Then, when the sink current I _C gradually increases and I _C >(I ₁ +I ₁ '+I ₂ +I ₂ '), the switching unit 130_2 performs switching of the transmission path P ₁₂ and the current path P ₂₂ to turn off the transmission. Path P ₁₂ and conduct current path P ₂₂ . At this time, the light emitting diode LD ₁₂ will generate a light source in response to the closing of the transmission path P ₁₂ , and the reference current I ₂ will be directed to the current collecting unit 120.

By analogy, the transmission paths P ₁₁ to P _{1N of the} switching units 130_1~130_N are sequentially turned off as the collecting current I _C increases, so that the light-emitting diodes LD ₁₁ to LD _1N generate light sources one by one. In addition, the current paths P ₂₁ -P _{2N of the} switching units 130_1~130_N are sequentially turned on as the collecting current I _C increases, so that the reference currents I ₁ -I _N are directed to the current collecting unit 120 one by one. . It is worth mentioning that if the reference current I _{i is} used to represent the i-th reference current and the current I _i ' is used to represent the current guided by the LED array to the i-th switching unit, then the k-th switching The condition for the unit 130_k to switch the transmission path P _1k and the current path P _2k is as shown in the formula (1):

In other words, as shown in equation (2):

When the collecting current I _C satisfies the condition shown in the formula (2), the first to kth switching units 130_1 to 130_k perform switching of the transmission path and the current path, and the (k+1)th to Nth switching units 130_1~130_k maintains the transmission path and the current path in the original state, and k is an integer not less than one. That is, the transmission paths P ₁₁ to P _1k at this time will be switched to the non-conducting state, and the transmission paths P _1(k+1) to P _1N will remain in the on state. Further, at this time, the current paths P ₂₁ to P _2k are switched to the on state, and the current paths P _2(k+1) to P _{2N are} maintained in the non-conduction state.

In summary, the light source control circuit of the present invention is a state in which a plurality of switching units are simultaneously operated by a current collecting unit. Thereby, as the collected current provided by the current collecting unit increases, the plurality of switching units will be sequentially switched, thereby causing the plurality of light emitting diodes to generate the light sources one by one. In this way, the present invention can reduce the complexity of the control circuit and at the same time take into account the overall performance of the circuit.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10. . . Lighting device

100‧‧‧Light source control

110‧‧‧current supply unit

120‧‧‧current collection unit

130_1~130_N‧‧‧Switch unit

LD ₁₁ ~LD _1N , LD ₂₁ ~LD ₂₃ ‧‧‧Light Emitting Diode

R _D , R _C , R ₁₁ ~R _1N ‧‧‧resistance

V _DD ‧‧‧Power supply voltage

SD ₁ ~SD _N ‧‧‧current source

I ₁ ~I _N ‧‧‧reference current

I _C ‧‧‧Collecting current

V _C ‧‧‧Control voltage

M _C , M ₁₁ ~M _1N , M ₂₁ ~M _2N ‧‧‧N type transistor

131_1~131_N, 132_1~132_N‧‧‧ pressure drop

ZD ₁₁ ~ZD _N1 , ZD ₁₂ ~ZD _N2 , ZD1~ZD3‧‧‧ Zener diode

P ₁₁ ~P _1N ‧‧‧Transmission path

P ₂₁ ~P _2N ‧‧‧ current path

CD ₁₁ , CD ₁₂ , CD ₂₁ , CD ₂₂ ‧ ‧ current direction

D ₁₁ ~ D ₁₃ , D ₂₁ ~ D ₂₃ , D ₃₁ ~ D ₃₃ ‧ ‧ diode

210, 220‧‧‧ diode series

1 is a circuit diagram of a lighting device in accordance with an embodiment of the present invention.

2A-2D are circuit diagrams of a voltage drop device according to another embodiment of the present invention, respectively.

10. . . Lighting device

100. . . Light source control

110. . . Current supply unit

120. . . Current collection unit

130_1~130_N. . . Switching unit

LD ₁₁ ~LD _1N , LD ₂₁ ~LD ₂₃ . . . Light-emitting diode

R _D , R _C , R ₁₁ ~R _1N . . . resistance

V _DD . . . voltage

SD ₁ ~ SD _N . . . Battery

I ₁ ~I _N . . . Reference current

I _C . . . Collecting current

V _C . . . Control voltage

M _C , M ₁₁ ~M _1N , M ₂₁ ~M _2N . . . N type transistor

131_1~131_N, 132_1~132_N. . . Pressure drop

ZD ₁₁ ~ ZD _N1 , ZD ₁₂ ~ ZD _N2 . . . Zener diode

P ₁₁ ~P _1N . . . Transmission path

P ₂₁ ~ P _2N . . . Current path

CD ₁₁ , CD ₁₂ , CD ₂₁ , CD ₂₂ . . . Current direction

Claims (15)

A light source control circuit for controlling N light-emitting diodes connected in series, N is a positive integer, and the light source control circuit comprises: a current supply unit for supplying N reference currents; and a current collecting unit for providing a current collection And adjusting the size of the collected current according to a level of the control voltage; and N switching units each having a transmission path and a current path, wherein the i-th switching unit transmits the transmission path and the ith The light-emitting diodes are connected in parallel with each other and are connected in series with the remaining switching units through the current path, and the i-th switching unit turns on the current path or the current path according to the magnitude of the collected current. Is the transmission path to transmit the ith reference current to the current collecting unit or to cause the ith LED to generate a light source, i being an integer and 1≦i≦N. The light source control circuit of claim 1, wherein the transmission paths of the switching units are sequentially turned off as the current is increased, so that the light emitting diodes are generated one by one. The light source, and the current paths of the switching units are sequentially turned on as the current is increased, so that the reference currents are guided to the current collecting unit one by one. The light source control circuit of claim 1, wherein the i-th switching unit comprises: a first N-type transistor, wherein the first end is electrically connected to the anode end of the i-th LED, the first The source terminal of the N-type transistor is electrically connected to the cathode end of the i-th LED, and the gate terminal electrical property of the first N-type transistor Connecting the current supply unit and receiving the ith reference current; a first voltage drop device having a first end electrically connected to the gate terminal of the first N-type transistor and a second end of the first voltage drop device Electrically connecting the source terminal of the first N-type transistor; a second N-type transistor, the 汲 is electrically connected to the gate terminal of the first N-type transistor, and the gate terminal of the second N-type transistor is electrically connected Connected to the source terminal of the first N-type transistor; and a second voltage drop device, the first end of which is electrically connected to the gate terminal of the second N-type transistor, and the second end of the second voltage drop device is electrically connected Connected to the source terminal of the second N-type transistor, wherein the ith switching unit transmits the gate terminal of the first N-type transistor and the source terminal of the second N-type transistor to the remaining switching units. Concatenation. The light source control circuit of claim 3, wherein the first voltage drop device comprises: a first Zener diode, the cathode end of which is electrically connected to the gate terminal of the first N-type transistor; a second Zener diode having an anode end electrically connected to the anode end of the first Zener diode, and a cathode end of the second Zener diode electrically connected to the source of the first N-type transistor extreme. The light source control circuit of claim 3, wherein the second voltage drop device is a resistor or a Zener diode, or the second voltage drop device is connected by a plurality of diodes. Or the second voltage drop device is formed by a plurality of diodes connected in series. The light source control circuit of claim 1, wherein the current collecting unit comprises: an N-type transistor, wherein the 汲 terminal is connected in series with the switching unit, and the gate terminal of the N-type transistor receives the control voltage; And a resistor, the first end of the resistor is electrically connected to the source terminal of the N-type transistor, and the second end of the resistor is electrically connected to a ground. The light source control circuit of claim 1, wherein the current supply unit comprises: N current sources, wherein the ith current source is electrically connected to the i-th switching unit, and provides an i-th reference current. A lighting device comprising: N first light emitting diodes, wherein the first light emitting diodes are connected in series between a power supply voltage and a ground, N is a positive integer; and a light source control circuit controls the The first light emitting diode, and the light source control circuit comprises: a current supply unit for supplying N reference currents; a current collecting unit for providing a collecting current, and adjusting the collecting current according to a level of the control voltage And a plurality of switching units each having a transmission path and a current path, wherein the i-th switching unit is connected in parallel with the i-th LED through the transmission path and has the same The current path and the remaining switching units are connected in series, and the i-th switching unit turns on the current path or the transmission path that the i-th switching unit transmits according to the magnitude of the collected current to transmit the ith reference current to the current path. Current collection unit or As a result, the i-th light-emitting diode cannot generate a light source, and i is an integer and 1≦i≦N. The illuminating device of claim 8, wherein the transmission paths of the switching units are sequentially turned off as the collecting current increases, so that the light emitting diodes generate light sources one by one. And the current paths of the switching units are sequentially turned on as the collecting current increases, so that the reference currents are respectively guided to the current collecting unit. The illuminating device of claim 8, wherein the i-th switching unit comprises: a first N-type transistor, the 汲 is electrically connected to the anode end of the ith LED, the first N The source terminal of the type transistor is electrically connected to the cathode end of the ith LED, the gate terminal of the first N-type transistor is electrically connected to the current supply unit, and receives the ith reference current; a first voltage a first end electrically connected to a gate terminal of the first N-type transistor, and a second end of the first voltage drop device electrically connected to a source terminal of the first N-type transistor; a second N a transistor, the 汲 is electrically connected to the gate terminal of the first N-type transistor, the gate terminal of the second N-type transistor is electrically connected to the source terminal of the first N-type transistor; and a second voltage a first end electrically connected to a gate terminal of the second N-type transistor, the second end of the second voltage drop device being electrically connected to a source terminal of the second N-type transistor, wherein the ith Switching units pass through the gate terminal of the first N-type transistor and the source terminal of the second N-type transistor to interact with the remaining switching units Concatenation. The illuminating device of claim 10, wherein the first voltage drop device comprises: a first Zener diode, the cathode end of which is electrically connected to the gate terminal of the first N-type transistor; a second Zener diode having an anode end electrically connected to an anode end of the first Zener diode, and a cathode end of the second Zener diode electrically connected to a source terminal of the first N-type transistor . The illuminating device of claim 10, wherein the second voltage drop device is a resistor or a Zener diode, or the second voltage drop device is formed by connecting a plurality of diodes in series. Or the second voltage drop device is formed by a plurality of diodes connected in series. The illuminating device of claim 8, wherein the current collecting unit comprises: an N-type transistor, wherein the 汲 terminal is connected in series with the switching unit, and the gate terminal of the N-type transistor receives the control voltage; a resistor, the first end of which is electrically connected to the source terminal of the N-type transistor, and the second end of the resistor is electrically connected to the ground. The illuminating device of claim 8, wherein the current supply unit comprises: N current sources, wherein the ith current source is electrically connected to the ith switching unit and provides an ith reference current. The illuminating device of claim 8, further comprising a plurality of second illuminating diodes and a resistor, wherein the second illuminating diodes and the first illuminating diodes are connected to the resistor Between the power supply voltage and the ground.