Circuit utilizing zero-crossing signal to cooperatively scan LED lamp
By combining the zero-crossing signal with the circuit for scanning LED lights, the problem of high hardware cost caused by the one-to-one control of LED lights and IO ports is solved, thus saving IO ports and reducing hardware costs.
Patent Information
- Application Number
- CN202422765163.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-13
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-11-13
AI Technical Summary
In the prior art, the control of LED lamps requires a one-to-one correspondence with IO ports, resulting in a significant increase in hardware costs when the number of LED lamps is large.
The circuit uses zero-crossing signals to scan LED lights. Through the zero-crossing detection unit and the LED light unit, the zero-crossing signal is used to achieve independent control of two LED lights. One IO port is shared, and four LED lights are controlled through two IO ports, using zero-crossing signal terminal multiplexing.
This saves IO ports and reduces hardware costs while maintaining the LED lighting effect.
Smart Images
Figure CN223334818U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of LED lamp driving circuits, and particularly relates to a circuit that utilizes a zero-crossing signal to scan an LED lamp. Background Art
[0002] LED light scanning and lighting control is widely used in electronic devices such as LED displays, signal lights, and digital tubes. In the existing technology, the control of LED lights is basically a one-to-one relationship. For example, scanning one LED light generally uses one IO port, where the IO port can be a drive pin of a microcontroller. Scanning two LED lights generally uses two IO ports, and scanning four LED lights generally uses three to four IO ports. Therefore, the number of IO ports needs to match the number of LED lights. More IO ports will lead to greater hardware costs, especially when there are a large number of LED lights, which will lead to a significant increase in hardware costs. Utility Model Content
[0003] The utility model aims to provide a circuit that utilizes a zero-crossing signal to scan an LED lamp, so as to save IO ports in an LED driving circuit and reduce hardware costs.
[0004] In order to achieve the above objectives, the present invention adopts the following technical solutions:
[0005] Provided is a circuit for scanning an LED lamp using a zero-crossing signal. The circuit includes a zero-crossing detection unit and an LED lamp unit. The zero-crossing detection unit includes a first current-limiting resistor and a diode connected in series between the positive electrode of an AC power supply and a ground terminal, and also includes a second current-limiting resistor and an electronic switch connected in series between the positive electrode of a DC power supply and a ground terminal. The control end of the electronic switch is electrically connected between the first current-limiting resistor and the diode, a first LED drive terminal is connected between the second current-limiting resistor and the electronic switch, and a zero-crossing signal terminal is connected from the first LED drive terminal via a third current-limiting resistor. The LED lamp unit is provided with a second LED drive terminal. The LED lamp unit includes a first LED lamp and a fourth current-limiting resistor connected in series between the first and second LED drive terminals, and also includes a second LED lamp and a fifth current-limiting resistor connected in series between the first and second LED drive terminals. The positive electrode of the first LED lamp is electrically connected to the second LED drive terminal, and the negative electrode of the second LED lamp is electrically connected to the second LED drive terminal.
[0006] Preferably, the electronic switch is an NPN transistor.
[0007] Preferably, the first current-limiting resistor includes two resistors connected in series.
[0008] Preferably, the resistance of the fourth current limiting resistor is equal to the sum of the resistances of the fifth current limiting resistor and the second current limiting resistor.
[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: the circuit for utilizing a zero-crossing signal to scan an LED lamp comprises a first current-limiting resistor, a second current-limiting resistor, a diode, and an electronic switch to form a zero-crossing detection unit, the main function of which is to form a square wave at the first LED drive terminal. The square wave enters the microcontroller through the third current-limiting resistor RS6 to provide a zero-crossing signal, and the scanning circuit of the two reverse-parallel LED lamps is current-limited through the second current-limiting resistor, the fourth current-limiting resistor, and the fifth current-limiting resistor. The first LED lamp and the second LED lamp are scanned through a second LED drive terminal, and the two LED lamps can be individually lit, neither lit, or both lit. Similarly, four LED lamps can be controlled through two IO ports, and eight LED lamps can be controlled through four IO ports, and the zero-crossing signal terminal SYS can be reused, thereby saving IO ports exponentially and reducing hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:
[0011] Figure 1 This is a circuit schematic diagram of an embodiment of the present invention having a circuit for utilizing a zero-crossing signal to scan an LED light. DETAILED DESCRIPTION
[0012] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0013] In one embodiment, a circuit is provided for scanning an LED lamp by using a zero-crossing signal. Figure 1 As shown, the circuit for scanning LED lamps using zero-crossing signals includes a zero-crossing detection unit and an LED lamp unit. The zero-crossing detection unit is mainly used to provide a zero-crossing signal. The LED lamp unit is a lamp group composed of LEDs and current-limiting resistors.
[0014] Among them, the zero-crossing detection unit includes a first current-limiting resistor and a diode DS1 for being connected in series between an AC power positive electrode ACL1 and a ground terminal GND. The first current-limiting resistor includes two resistors connected in series, namely resistor RS4 and resistor RS5. By setting two resistors in series, the selection of resistors is facilitated.
[0015] The AC power supply positive electrode ACL1 can use the mains live terminal to provide a 50Hz power supply. The zero-crossing detection unit also includes a second current-limiting resistor RS1 and an electronic switch QS1, which are connected in series between a DC power supply positive electrode (+5V) and a ground terminal GND. The positive electrode of the diode DS1 is grounded, which is used to protect the electronic switch QS1 during the negative half cycle of the AC power supply. The electronic switch QS1 is an NPN-type transistor suitable for use as a control switch at the low voltage end. The control terminal of the electronic switch QS1 is electrically connected between the resistor RS5 in the first current-limiting resistor and the diode DS1. When the AC power supply positive electrode ACL1 is at the positive half cycle voltage, the electronic switch QS1 is turned on.
[0016] A first LED drive terminal (point B) is connected between the second current-limiting resistor RS1 and the electronic switch QS1. The first LED drive terminal provides a square wave signal that has two functions: one is to drive the LED, and the other is to connect the first LED drive terminal (point B) to a zero-crossing signal terminal SYS through a third current-limiting resistor RS6. The zero-crossing signal terminal SYS is used to provide a zero-crossing signal to the microcontroller.
[0017] The LED lamp unit is provided with a second LED driving terminal IO1, which is also used to be electrically connected to the microcontroller. The microcontroller uses the zero-crossing signal provided by the zero-crossing signal terminal SYS as a reference to control the high and low levels of the second LED driving terminal IO1.
[0018] The LED lamp unit includes a first LED lamp S-LED1 and a fourth current-limiting resistor RS2 connected in series between the first LED drive terminal (point B) and the second LED drive terminal IO1, and also includes a second LED lamp S-LED2 and a fifth current-limiting resistor RS3 connected in series between the first LED drive terminal (point B) and the second LED drive terminal IO1, which is equivalent to two LED lamps each connected in series with a current-limiting resistor and then connected in parallel, wherein the positive pole of the first LED lamp S-LED1 is electrically connected to the second LED drive terminal IO1, and the negative pole of the second LED lamp S-LED2 is electrically connected to the second LED drive terminal IO1. When the second LED drive terminal IO1 is at a high level and the electronic switch QS1 is turned on, the first LED lamp S-LED1 lights up; when the second LED drive terminal IO1 is at a low level and the electronic switch QS1 is closed so that the first LED drive terminal is at a high level, the second LED lamp S-LED2 lights up.
[0019] The resistance of the fourth current limiting resistor RS2 is equal to the sum of the fifth current limiting resistor RS3 and the second current limiting resistor RS1. This is mainly because when the first LED lamp S-LED1 and the second LED lamp S-LED2 have the same specifications, when the second LED lamp S-LED2 is turned on, the +5V DC power supply is used to power the second LED lamp S-LED2 through the second current limiting resistor RS1 and the fifth current limiting resistor RS3. When the first LED lamp S-LED1 is turned on, the power supply provided by the second LED drive terminal IO1 is used to power the first LED lamp S-LED2 through the fourth current limiting resistor RS2 and the electronic switch QS1. That is, for the first LED lamp S-LED1 and the second LED lamp S-LED2 with the same specifications, the current limiting effect of the fourth current limiting resistor RS2 and the sum of the fifth current limiting resistor RS3 and the second current limiting resistor RS1 are the same.
[0020] Based on the above embodiments, it can be seen that the circuit with the use of zero-crossing signal to scan LED lights is composed of a first current limiting resistor (resistors RS4 and RS5 in series), a second current limiting resistor RS1, a diode DS1, and an electronic switch QS1 to form a zero-crossing detection unit. Figure 1 Point B (the first LED driver terminal) forms a 50HZ square wave, which enters the microcontroller (such as a single-chip microcomputer chip) through the third current-limiting resistor RS6, providing a zero-crossing signal; the second current-limiting resistor RS1, the fourth current-limiting resistor RS2, and the fifth current-limiting resistor RS3 are used to limit the current of the scanning circuit of the two reverse-parallel LED lamps. The first LED lamp S-LED1 and the second LED lamp S-LED2 are scanned through a common IO port (the second LED driver terminal IO1), which can realize the lighting of each of the two LED lamps separately, neither of them is lit, or both of them are lit. Similarly, four LED lamps can be controlled through two IO ports, and eight LED lamps can be controlled through four IO ports. The zero-crossing signal terminal SYS can be reused, so the IO ports are saved exponentially and the hardware cost is reduced.
[0021] Combine Figure 1 As shown, the circuit for scanning LED lights using a zero-crossing signal works as follows:
[0022] If it is necessary to light up the first LED lamp S-LED1, the second LED drive terminal IO1 is controlled by the microcontroller to output a high level. If the zero-crossing square wave at point B (the first LED drive terminal IO1) is at a high level, both lamps are off. However, when the zero-crossing square wave is at a low level, the first LED lamp S-LED1 will light up and the second LED lamp S-LED2 will not light up. Therefore, when the first LED drive terminal IO1 is at a high level, the first LED lamp S-LED1 will light up for half a cycle and off for half a cycle. However, since the frequency of the square wave is 50HZ, it appears to the human eye that the first LED lamp S-LED1 is always on.
[0023] If you need to light up the second LED lamp S-LED2, the microcontroller controls the second LED drive terminal IO1 to output a low level. If the zero-crossing square wave is at a low level, both lights are off. However, when the zero-crossing square wave is at a high level, the second LED lamp S-LED2 lights up and the first LED lamp S-LED1 does not light up. Therefore, when the second LED drive terminal IO1 is at a low level, the second LED lamp S-LED2 lights up for half a cycle and does not light up for half a cycle. However, since the square wave frequency is 50HZ, it appears to the human eye that the second LED lamp S-LED2 is always on.
[0024] When you need to control both lights to be off, you only need to configure the second LED driver terminal IO1 of the microcontroller as a high-impedance input. At this time, no matter what the zero-crossing state is, the first LED light S-LED1 and the second LED light S-LED2 will not light up.
[0025] When it is necessary to control two lamps to light up at the same time, the microcontroller can use the zero-crossing signal level state provided by the zero-crossing signal terminal SYS as a reference. When the zero-crossing signal is at a high level, the software in the microcontroller controls the second LED drive terminal to be at a low level. When the zero-crossing signal is at a low level, the software in the microcontroller controls the second LED drive terminal IO1 to be at a high level. That is, in a complete zero-crossing cycle, the first LED lamp S-LED1 and the second LED lamp S-LED2 can be lit separately. Therefore, when the two lamps are lit at the same time, the microcontroller only needs to cooperate with the level of the zero-crossing signal provided by the zero-crossing signal terminal SYS to output the level of the second LED drive terminal IO1 to operate the lighting state of the two lamps.
[0026] Based on the above embodiments, it can be seen that the circuit for scanning LED lights using a zero-crossing signal utilizes the zero-crossing flipping characteristic of a square wave signal to enable one common IO port to scan two LED lights. If two common IO ports are used, four LED lights can be scanned, thus saving IO ports and reducing hardware costs. During the LED scanning process using a zero-crossing signal, the frequency of the zero-crossing signal is 50 Hz. Based on this frequency, the scanning frequency of the LED lights is also 50 Hz. The scanning frequency does not cause the LED to visually flicker, and the LED is in a constant lighting effect.
[0027] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.
[0028] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A circuit for scanning an LED light using a zero-crossing signal, characterized in that: The invention comprises a zero-crossing detection unit and an LED lamp unit, wherein the zero-crossing detection unit comprises a first current-limiting resistor and a diode connected in series between the positive pole of an AC power supply and a ground terminal, and further comprises a second current-limiting resistor and an electronic switch connected in series between the positive pole of a DC power supply and a ground terminal, wherein the control end of the electronic switch is electrically connected between the first current-limiting resistor and the diode, a first LED drive terminal is led out between the second current-limiting resistor and the electronic switch, and a zero-crossing signal terminal is led out from the first LED drive terminal via a third current-limiting resistor; the LED lamp unit is provided with a second LED drive terminal, and comprises a first LED lamp and a fourth current-limiting resistor connected in series between the first LED drive terminal and the second LED drive terminal, and further comprises a second LED lamp and a fifth current-limiting resistor connected in series between the first LED drive terminal and the second LED drive terminal, wherein the positive pole of the first LED lamp is electrically connected to the second LED drive terminal, and the negative pole of the second LED lamp is electrically connected to the second LED drive terminal.
2. The circuit for scanning an LED lamp using a zero-crossing signal according to claim 1, characterized in that: The electronic switch is an NPN transistor.
3. The circuit for scanning an LED lamp by using a zero-crossing signal according to claim 1, wherein: The first current-limiting resistor includes two resistors connected in series.
4. The circuit for scanning an LED lamp using a zero-crossing signal according to claim 1, wherein: The resistance of the fourth current limiting resistor is equal to the sum of the resistances of the fifth current limiting resistor and the second current limiting resistor.