TW202344138A - Light source driving device capable of truly restoring actual dimming voltage at different temperatures without changing production cost, improving the detection accuracy of the dimming voltage, and reducing negative impact caused by the series connection of diodes at the dimming input terminal - Google Patents

Abstract

The present invention discloses a light source driving device, which includes a first diode, a second diode and a driving chip. The first diode is coupled to a first dimming input terminal, and the second diode is coupled to a second dimming input terminal. The driving chip is coupled to the first diode, the second diode and a light source. The first diode and the second diode have the same specifications and are located in an isothermal environment. The first dimming input terminal and the second dimming input terminal are configured to receive dimming voltages. The driving chip generates two equal fixed currents passing through the first diode and the second diode respectively, so that the fixed currents and the dimming voltages are used to generate a first driving voltage between the first diode and the driving chip and a second driving voltage between the driving chip and the second diode. The driving chip restores the dimming voltages and drives the light source according to the first driving voltage and the second driving voltage.

Description

Light source driving device

The present invention relates to a driving device, and in particular to a light source driving device.

Light-emitting diode lighting has three main advantages, namely energy saving, environmental protection and green lighting. Because light-emitting diodes have high luminous efficiency and low production costs, their application prospects and markets are very broad, making light-emitting diodes one of the new generation light sources that replace traditional light sources in the world today.

The current dimming port of the light-emitting diode driver is designed to prevent high voltage from being mistakenly connected, or when the dimming ports of multiple light-emitting diode drivers are connected in parallel, one of the light-emitting diode drivers is damaged and all of them are paralyzed. A diode 10 is connected to the input terminal, as shown in Figure 1. Although this measure is simple and low-cost, it will cause two problems. Since there is a voltage drop in the diode 10, the actual voltage between the positive and negative input terminals of the dimming port is different from the dimming voltage actually received by the light-emitting diode driver. The conversion chip in the light-emitting diode driver currently on the market cannot automatically eliminate the influence of the voltage drop on the diode 10. Some manufacturers do not consider the voltage drop of the diode 10 at all, while other manufacturers simply subtract it. 0.5 volts, not taking into account the difference in voltage drop across different types of diodes 10. In addition, since the diode is a nonlinear element. When the temperature changes, the voltage drop on the diode also changes, as shown in Figure 2, and it changes in a nonlinear form, making the dimming voltage level between the positive and negative input terminals of the dimming port comparable. There is a more serious deviation from the brightness level output by the LED driver. In Figure 2, four different data correspond to four different forward bias voltages from top to bottom, which are 100, 10, 1 and 0.1 mA in order.

Therefore, the present invention aims to solve the above-mentioned problems by proposing a light source driving device to solve the conventional problems.

The present invention provides a light source driving device that can truly restore the actual dimming voltage at different temperatures without changing the production cost, improve the detection accuracy of the dimming voltage, and improve the performance of the diode connected in series at the dimming input end. negative impact.

To achieve the above object, the present invention provides a light source driving device coupled to a light source. The light source driving device includes a first diode, a first driving chip, a second diode and a second driving chip. The cathode of the first diode is coupled to the first dimming input terminal, and the first driving chip is coupled to the anode of the first diode and the second dimming input terminal. The first dimming input terminal and the second dimming input terminal are used to receive a dimming voltage. The first driving chip is used to generate a first fixed current through the first diode and utilize the first fixed current and the dimming voltage. A first driving voltage is generated at a first node between the first diode and the first driving chip. The cathode of the second diode is coupled to the ground terminal, and the anode of the second diode is coupled to a fixed current source. The fixed current source is used to generate a second fixed current through the second diode. The second fixed current is equal to the first fixed current. The first diode and the second diode have the same specifications and are located in an isothermal environment. The second fixed current generates a second driving voltage at a second node between the fixed current source and the second diode. The second driving chip is coupled to the light source, the first node and the second node. The second driving chip is used to receive the first driving voltage and the second driving voltage, and drive the light source accordingly.

In one embodiment of the present invention, the light source driving device further includes a first filter circuit coupled between the first node and the second driver chip. The second driver chip is used to receive the first driver through the first filter circuit. voltage.

In one embodiment of the present invention, the light source driving device further includes a second filter circuit coupled between the second node and the second driver chip. The second driver chip is used to receive the second driver through the second filter circuit. voltage.

In one embodiment of the invention, the first diode and the second diode are located on the same printed circuit board.

In one embodiment of the present invention, the fixed current source includes a fixed voltage source and a resistor. The resistor is coupled between the fixed voltage source and the second node. The fixed voltage source is used to generate a second fixed voltage through the resistor. current.

In one embodiment of the invention, the light source is a light emitting diode.

In one embodiment of the present invention, a light source driving device is coupled to a light source. The light source driving device includes a first diode, a second diode and a driving chip. The cathode of the first diode is coupled to the first dimming input terminal, and the cathode of the second diode is coupled to the second dimming input terminal. The first diode and the second diode have the same specifications and are located in an isothermal environment. The first dimming input terminal and the second dimming input terminal are used to receive a dimming voltage. The driving chip is coupled to the anodes and the light source of the first diode and the second diode. The driving chip is used to generate a first fixed current and a second fixed current that pass through the first diode and the second diode respectively, and the second fixed current is equal to the first fixed current. The driving chip is used to generate a first driving voltage at a first node between the first diode and the driving chip by using the first fixed current and the dimming voltage, and the second fixed current is used at the first node between the driving chip and the second diode. The second node generates a second driving voltage, and the driving chip is used to receive the first driving voltage and the second driving voltage, and drive the light source accordingly.

In one embodiment of the present invention, the light source driving device further includes a filter circuit coupled between the first node and the driving chip. The driving chip is used to receive the first driving voltage through the filter circuit.

In one embodiment of the invention, the first diode and the second diode are located on the same printed circuit board.

In one embodiment of the invention, the light source is a light emitting diode.

Based on the above, the light source driving device places a diode and the diode connected to the dimming input terminal in an isothermal environment. At the same time, the first diode and the second diode are designed to have the same specifications, and when the same current passes through Under the premise of connecting the first diode and the second diode, the forward bias voltage of the second diode can be obtained. In this way, the actual dimming voltage can be truly restored at different temperatures without changing the manufacturing process. cost, improve the detection accuracy of dimming voltage, and improve the negative impact caused by the series connection of diodes at the dimming input end.

In order to enable your review committee to have a better understanding of the structural features and effects of the present invention, we would like to provide you with a diagram of the preferred embodiment and a detailed description, as follows:

The embodiments of the present invention will be further explained below with reference to relevant drawings. Wherever possible, the same reference numbers are used in the drawings and description to refer to the same or similar components. In the drawings, shapes and thicknesses may be exaggerated for simplicity and ease of notation. It should be understood that components not specifically shown in the drawings or described in the specification are in forms known to those of ordinary skill in the art. Those skilled in the art can make various changes and modifications based on the contents of the present invention.

When an element is referred to as being "on", it can generally mean that the element is directly on the other element, or that the other element exists between them. Conversely, when an element is said to be "directly on" another element, it cannot have other elements between them. As used herein, the term "and/or" includes any combination of one or more of the associated listed items.

References below to "one embodiment" or "an embodiment" refer to a particular element, structure, or feature associated with at least one embodiment. Therefore, “one embodiment” or multiple descriptions of “an embodiment” appearing in multiple places below are not directed to the same embodiment. Furthermore, specific components, structures and features in one or more embodiments may be combined in an appropriate manner.

The disclosure is specifically described with the following examples. These examples are only for illustration, because for those who are familiar with this art, various modifications and modifications can be made without departing from the spirit and scope of the disclosure. Therefore, this disclosure The scope of protection of the disclosed content shall be determined by the scope of the patent application attached. Throughout the specification and claims, unless the content clearly dictates otherwise, the meaning of "a" and "the" includes such statements including "one or at least one" of the element or component. Furthermore, as used in this disclosure, the singular article also includes recitations of plural elements or ingredients unless it is obvious from the particular context that the plural is excluded. Furthermore, as applied to this description and all claims below, "in" may mean "in" and "on" unless the context clearly dictates otherwise. Unless otherwise noted, the terms used throughout the specification and patent claims generally have their ordinary meanings as used in the field, in the disclosure and in the particular context. Certain terms used to describe the disclosure are discussed below or elsewhere in this specification to provide practitioners with additional guidance in describing the disclosure. The use of examples anywhere throughout this specification, including the use of examples of any terminology discussed herein, is for illustrative purposes only and does not, of course, limit the scope and meaning of the disclosure or any exemplified terminology. Likewise, the present disclosure is not limited to the various embodiments set forth in this specification.

It should be understood that the terms "comprising", "including", "having", "containing", "involving", etc., as used herein, are open-ended (open-ended), meaning including but not limited to. In addition, any embodiment or patentable scope of the present invention does not necessarily achieve all the purposes, advantages or features disclosed in the present invention. In addition, the abstract part and title are only used to assist in searching for patent documents and are not used to limit the scope of the patent application for the invention.

Unless otherwise specified, some conditional sentences or words, such as "can", "could", "might", or "may", usually try to express that the embodiment of this case has, But it can also be interpreted as features, components, or steps that may not be needed. In other embodiments, these features, elements, or steps may not be required.

A light source driving device will be described below, which places a diode and a diode connected to a dimming input terminal in an isothermal environment. At the same time, the first diode and the second diode are designed to have the same specifications. Under the premise that the same current passes through the first diode and the second diode, the forward bias voltage of the second diode is obtained. In this way, the actual dimming voltage can be truly restored at different temperatures, and It does not change the production cost, improves the detection accuracy of dimming voltage, and improves the negative impact caused by the series connection of diodes at the dimming input end.

Figure 3 is a schematic diagram of the first embodiment of the light source driving device of the present invention. Referring to Figure 3, the first embodiment of the light source driving device 2 is introduced below. The light source driving device 2 is coupled to a light source 3. The light source 3 is a light emitting diode as an example, but the invention is not limited thereto. The light source driving device 2 includes a first diode 20, a first driving chip 21, a second diode 22, a second driving chip 23, a fixed current source 24, a first dimming input terminal 25 and a second dimming input terminal 26. The cathode of the first diode 20 is coupled to the first dimming input terminal 25 , and the first driving chip 21 is coupled to the fixed voltage source VCC, the anode of the first diode 20 and the second dimming input terminal 25 . The cathode of the second diode 22 is coupled to the ground, and the anode of the second diode 22 is coupled to the fixed current source 24 . The second driving chip 23 is coupled to the fixed voltage source VDD, the light source 3 , the first node N1 between the first diode 20 and the first driving chip 21 and the third node between the fixed current source 24 and the second diode 22 . Two nodes N2. The first diode 20 and the second diode 22 have the same specifications, such as the same size and doping concentration of semiconductor carriers, and the first diode 20 and the second diode 22 are located in an isothermal environment. . For example, the first diode 20 and the second diode 22 can be located on the same printed circuit board, and the distance between them is less than 5 centimeters. As a result, when the temperature changes, the voltage drops across the first diode 20 and the second diode 22 also change similarly. That is to say, no matter how the temperature changes, the temperature received by the first diode 20 and the second diode 22 is the same. If the current passing through the first diode 20 and the second diode 22 is designed, are the same, which means that the forward bias voltages of the first diode 20 and the second diode 22 are also the same.

The operation process of the first embodiment of the light source driving device 2 is introduced below. The first dimming input terminal 25 and the second dimming input terminal 26 receive a dimming voltage VD, the first driving chip 21 generates a first fixed current I1 through the first diode 20, and uses the first fixed current I1 and The dimming voltage VD generates the first driving voltage V1 at the first node N1 between the first diode 20 and the first driving chip 21 . The fixed current source 24 generates a second fixed current I2 passing through the second diode 22, and the second fixed current I2 is designed to be equal to the first fixed current I1, so that the first diode 20 and the second diode 22 are in forward direction. The bias voltage is the same. The second fixed current I2 generates the second driving voltage V2 at the second node N2 between the fixed current source 24 and the second diode 22 . The second driving chip 23 receives the first driving voltage V1 and the second driving voltage V2, and drives the light source 3 accordingly. Because the first driving voltage V1 is equal to the forward bias voltage of the first diode 20 plus the dimming voltage VD, and the forward bias voltages of the first diode 20 and the second diode 22 are the same, the second driving voltage V1 is equal to the forward bias voltage of the first diode 20 plus the dimming voltage VD. The chip 23 subtracts the first driving voltage V1 from the second driving voltage V2 to truly restore the dimming voltage VD at any temperature without changing the production cost, improves the detection accuracy of the dimming voltage VD, and improves the dimming input. Negative effects caused by connecting diodes in series.

In order to improve the accuracy of the first driving voltage V1 and the second driving voltage V2, in some embodiments of the present invention, the light source driving device 2 may further include a first filter circuit 27 and a second filter circuit 28. The first filter circuit 27 is coupled between the first node N1 and the second driving chip 23 . The second driving chip 23 receives the first driving voltage V1 through the first filter circuit 27 . The second filter circuit 28 is coupled between the second node N2 and the second driving chip 23 . The second driving chip 23 receives the second driving voltage V2 through the second filter circuit 28 . In addition, in a specific implementation circuit, the fixed current source 24 may include a fixed voltage source VDD and a resistor 240 . The resistor 240 is coupled between the fixed voltage source VDD and the second node N2. The fixed voltage source VDD generates a second fixed current I2 through the resistor 240.

Figure 4 is a schematic diagram of the second embodiment of the light source driving device of the present invention. Referring to FIG. 4 , the second embodiment of the light source driving device 4 is introduced below. The light source driving device 4 is coupled to a light source 5. The light source 5 is a light emitting diode as an example, but the invention is not limited thereto. The light source driving device 4 includes a first diode 40, a second diode 41, a driving chip 42, a first dimming input terminal 43 and a second dimming input terminal 44, wherein the second dimming input Terminal 44 is coupled to ground. The cathode of the first diode 40 is coupled to the first dimming input terminal 43 , and the cathode of the second diode 41 is coupled to the second dimming input terminal 44 . The first diode 40 and the second diode 41 have the same specifications, such as the same size and doping concentration of semiconductor carriers, and the first diode 40 and the second diode 41 are located in an isothermal environment. . For example, the first diode 40 and the second diode 41 can be located on the same printed circuit board, and the distance between them is less than 5 centimeters. As a result, when the temperature changes, the voltage drop across the first diode 40 and the second diode 41 also changes in the same way. That is to say, no matter how the temperature changes, the temperature received by the first diode 40 and the second diode 41 is the same. If the current passing through the first diode 40 and the second diode 41 is designed, are the same, which means that the forward bias voltages of the first diode 40 and the second diode 41 are also the same. The driving chip 42 is coupled to the anodes of the first diode 40 and the second diode 41 and the light source 5 .

The operation process of the second embodiment of the light source driving device 4 is introduced below. The first dimming input terminal 43 and the second dimming input terminal 44 receive a dimming voltage VD, and the driving chip 42 generates the first fixed current I1 and the second fixed current I1 through the first diode 40 and the second diode 41 respectively. The current I2 is fixed, and the second fixed current I2 is designed to be equal to the first fixed current I1, so that the forward bias voltages of the first diode 40 and the second diode 41 are the same. The driving chip 42 uses the first fixed current I1 and the dimming voltage VD to generate the first driving voltage V1 at the first node N1 between the first diode 40 and the driving chip 42, and the second fixed current I2 flows between the driving chip 42 and the third driving chip 42. The second node N2 between the two diodes 41 generates the second driving voltage V2. The driving chip 42 receives the first driving voltage V1 and the second driving voltage V2, and drives the light source 5 accordingly. Because the first driving voltage V1 is equal to the forward bias voltage of the first diode 40 plus the dimming voltage VD, and the forward bias voltages of the first diode 40 and the second diode 41 are the same, the driving chip 42 Subtracting the first driving voltage V1 from the second driving voltage V2 can truly restore the dimming voltage VD at any temperature without changing the production cost, improve the detection accuracy of the dimming voltage VD, and improve the dimming input terminal string. Negative effects caused by connecting diodes.

In order to improve the accuracy of the first driving voltage V1, in some embodiments of the present invention, the light source driving device 4 may further include a filter circuit 45, which is coupled between the first node N1 and the driving chip 42. The driving chip 42 receives the first driving voltage V1 through the filter circuit 45 .

Figure 5 is a schematic diagram of the third embodiment of the light source driving device of the present invention. The difference between the third embodiment and the second embodiment is that the filter circuit 45 of the third embodiment is integrated in the driver chip 42 and coupled to the first node N1 to reduce circuit complexity. The driving chip 42 uses the filter circuit 45 to receive the first driving voltage V1.

According to the above embodiment, the light source driving device places the second diode and the first diode connected to the dimming input terminal in an isothermal environment, and at the same time designs the first diode and the second diode to have the same specifications. And under the premise that the same current passes through the first diode and the second diode, the forward bias voltage of the second diode is obtained. In this way, the actual dimming voltage can be truly restored at different temperatures. , without changing the production cost, improving the detection accuracy of the dimming voltage, and improving the negative impact caused by the series connection of the diode at the dimming input end.

The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Therefore, all equal changes and modifications can be made in accordance with the shape, structure, characteristics and spirit described in the patent scope of the present invention. , should be included in the patent scope of the present invention.

10: Diode 2:Light source driving device 20:First diode 21: First driver chip 22: Second diode 23: Second driver chip 24: Fixed current source 240:Resistor 25: First dimming input terminal 26: Second dimming input terminal 27: First filter circuit 28: Second filter circuit 3:Light source 4:Light source driving device 40:First diode 41: Second diode 42: Driver chip 43: First dimming input terminal 44: Second dimming input terminal 45: Filter circuit 5:Light source N1: first node N2: second node VD: dimming voltage I1: first fixed current I2: second fixed current V1: first driving voltage V2: second driving voltage VCC, VDD: fixed voltage source

Figure 1 is a schematic diagram of a prior art light emitting diode driver. Figure 2 is a graph of junction temperature and forward bias voltage of a light-emitting diode in the prior art. Figure 3 is a schematic diagram of the first embodiment of the light source driving device of the present invention. Figure 4 is a schematic diagram of the second embodiment of the light source driving device of the present invention. Figure 5 is a schematic diagram of the third embodiment of the light source driving device of the present invention.

2:Light source driving device

20:First diode

21: First driver chip

22: Second diode

23: Second driver chip

24: Fixed current source

240:Resistor

25: First dimming input terminal

26: Second dimming input terminal

27: First filter circuit

28: Second filter circuit

3:Light source

N1: first node

N2: second node

VD: dimming voltage

I1: first fixed current

I2: second fixed current

V1: first driving voltage

V2: second driving voltage

VCC, VDD: fixed voltage source

Claims (10)

A light source driving device, coupled to a light source, the light source driving device includes: a first diode, the cathode of which is coupled to the first dimming input terminal; A first driver chip is coupled to the anode of the first diode and the second dimming input terminal, wherein the first dimming input terminal and the second dimming input terminal are used to receive a dimming voltage, and the first dimming input terminal is used to receive a dimming voltage. A driver chip is used to generate a first fixed current through the first diode, and utilize the first fixed current and the dimming voltage to create a first voltage between the first diode and the first driver chip. The node generates a first driving voltage; A second diode, its cathode is coupled to the ground terminal, and its anode is coupled to a fixed current source, wherein the fixed current source is used to generate a second fixed current through the second diode, and the second fixed current is equal to the first A fixed current, the first diode and the second diode have the same specifications and are located in an isothermal environment. The second fixed current is between the fixed current source and the second diode. The node generates a second drive voltage; and A second driving chip is coupled to the light source, the first node and the second node, wherein the second driving chip is used to receive the first driving voltage and the second driving voltage, and drive the light source accordingly. The light source driving device according to claim 1, further comprising a first filter circuit coupled between the first node and the second driver chip, the second driver chip is used to receive the signal through the first filter circuit. the first driving voltage. The light source driving device according to claim 2, further comprising a second filter circuit coupled between the second node and the second driver chip, the second driver chip is used to receive the signal through the second filter circuit. the second driving voltage. The light source driving device of claim 1, wherein the first diode and the second diode are located on the same printed circuit board. The light source driving device as claimed in claim 1, wherein the fixed current source includes: a fixed voltage source; and A resistor is coupled between the fixed voltage source and the second node, wherein the fixed voltage source is used to generate the second fixed current through the resistor. The light source driving device according to claim 1, wherein the light source is a light emitting diode. A light source driving device, coupled to a light source, the light source driving device includes: a first diode, the cathode of which is coupled to the first dimming input terminal; A second diode, the cathode of which is coupled to the second dimming input terminal, wherein the first diode and the second diode have the same specifications and are located in an isothermal environment, the first dimming input terminal and the second dimming input terminal for receiving a dimming voltage; and A driving chip is coupled to the anodes of the first diode and the second diode and the light source, wherein the driving chip is used to generate the first light through the first diode and the second diode respectively. A fixed current and a second fixed current. The second fixed current is equal to the first fixed current. The driver chip is used to utilize the first fixed current and the dimming voltage between the first diode and the driver chip. The first node generates a first driving voltage, the second fixed current generates a second driving voltage at the second node between the driving chip and the second diode, and the driving chip is used to receive the first driving voltage and the second diode. a second driving voltage, and drive the light source accordingly. The light source driving device of claim 7 further includes a filter circuit coupled between the first node and the driving chip, and the driving chip is used to receive the first driving voltage through the filter circuit. The light source driving device of claim 7, wherein the first diode and the second diode are located on the same printed circuit board. The light source driving device according to claim 7, wherein the light source is a light emitting diode.

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