A constant voltage driven COB light source

Abstract

The present invention discloses a constant-voltage driven COB light source, comprising a COB substrate and at least one set of light-emitting modules packaged on the COB substrate. Each light-emitting module includes a corresponding LED module and a low-voltage linear constant-current chip. The LED module includes at least one LED chip, and the LED chip and the low-voltage linear constant-current chip are integrally packaged on the COB substrate using a bare die method. The positive electrode of the LED module is connected to an external power supply, which provides a low-voltage DC power supply of 12 to 42V for the LED chip. The negative electrode of the LED module is connected in series with the low-voltage linear constant-current chip, which converts the low-voltage DC power output by the external power supply into a constant-current power supply to drive the LED chip. Using the present invention, the constant-voltage power output by the external power supply can be converted into a constant-current power supply, and the light-emitting modules can be driven by a low-voltage linear drive method, which is more conducive to the centralized use of lamps.

Description

Technical Field

[0001] The present invention relates to the field of LED technology, and in particular to a constant voltage driven COB light source. Background Art

[0002] In traditional LED applications, due to the inherent nonlinear VI characteristics of LEDs, constant-current power supplies are essential. If multiple LED light sources are connected in parallel and share a high-current LED driver, uneven brightness across different groups of LEDs can occur. Furthermore, the number of LED light source groups varies, requiring adjustments to the output current. Furthermore, if an LED source powered by a high-current LED driver experiences an open or short circuit, it can cause overcurrent or even failure in other LED sources. Therefore, each LED source requires its own dedicated constant-current driver.

[0003] Currently, COB light sources are primarily used in commercial lighting, and track spotlights are a particularly widespread and widely used fixture within this market. Track spotlights feature a narrow-angle lighting system with a track that provides AC mains power or low-voltage DC power. Typically, each track spotlight is equipped with a dedicated constant-current driver. Therefore, it's essential to design a COB light source capable of constant voltage operation, directly driven by a low-voltage DC power supply. This significantly reduces the size, cost, and design of the track spotlight. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a small-sized, highly integrated constant-voltage driven COB light source, which can convert the constant voltage power output by an external power supply into a constant current power supply and drive the light-emitting module through a low-voltage linear drive method, which is more conducive to the centralized use of lamps.

[0005] In order to solve the above technical problems, the present invention provides a constant voltage driven COB light source, including a COB substrate and at least one group of light-emitting modules packaged on the COB substrate, each light-emitting module including a one-to-one corresponding LED module and a low-voltage linear constant current chip; the LED module includes at least one LED chip, and the LED chip and the low-voltage linear constant current chip are integrated and packaged on the COB substrate in a bare crystal manner; the positive pole of the LED module is connected to an external power supply, and the external power supply is used to provide a low-voltage DC power supply of 12 to 42V for the LED chip; the negative pole of the LED module is connected in series with a low-voltage linear constant current chip, and the low-voltage linear constant current chip is used to convert the low-voltage DC power output by the external power supply into a constant current power supply to drive the LED chip to work.

[0006] As an improvement to the above solution, the low-voltage linear constant current chip is fixed on the pad in the dam area of ​​the COB substrate and covered with dam glue.

[0007] As an improvement to the above solution, the COB substrate is a metal substrate or a ceramic substrate.

[0008] As an improvement to the above solution, the color excited by the LED chip is white light.

[0009] As an improvement to the above solution, the LED chip is a face-up LED chip or a flip-chip LED blue light chip.

[0010] As an improvement to the above solution, a group of light-emitting modules is packaged on the COB substrate.

[0011] As an improvement to the above solution, multiple groups of light-emitting modules with different color temperatures are packaged on the COB substrate.

[0012] As an improvement to the above solution, the low-voltage linear constant current chip is provided with an overvoltage and overheating protection unit.

[0013] As an improvement to the above solution, the low-voltage linear constant current chip is provided with a PWM port.

[0014] The beneficial effects of implementing the present invention are:

[0015] The constant voltage driven COB light source of the present invention has a built-in low voltage linear constant current chip. The low voltage linear constant current chip can convert the constant voltage power output by the external power supply into a constant current power supply, and drive the LED chip through a low voltage linear drive mode, which is more conducive to the centralized use of lamps.

[0016] In addition, the present invention realizes the systematic packaging of bare crystals with mixed multiple chip types by integrating the bare crystal LED chip and the low-voltage linear constant current chip into the COB substrate in a bare crystal manner, which can effectively reduce the heat dissipation thermal resistance and improve the heat dissipation efficiency. The installation process is simple, the installation and cost of the entire lamp are greatly reduced, and large-scale automated production is convenient.

[0017] Furthermore, the present invention can effectively improve product reliability by providing overvoltage and overheating protection units on the low-voltage linear constant current chip, which is beneficial to the use environment of large-scale commercial lighting lamps and has a wide range of market applications. At the same time, by providing a PWM port on the low-voltage linear constant current chip, the dimming function can be easily realized, which is highly flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of a circuit for driving a COB light source with a constant voltage according to the present invention;

[0019] Figure 2This is a schematic diagram of the structure of the low-voltage linear constant-current chip for constant-voltage driving COB light sources of the present invention;

[0020] Figure 3 This is a structural diagram of a constant voltage driven COB light source of the present invention;

[0021] Figure 4 This is another structural diagram of the constant voltage driven COB light source of the present invention. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] See also Figure 1 , Figure 1 The specific structure of the constant-voltage driven COB light source of the present invention is shown, which includes a COB substrate and at least one group of light-emitting modules packaged on the COB substrate, each light-emitting module includes a one-to-one corresponding LED module 2 and a low-voltage linear constant current chip 1; the LED module 2 includes at least one LED chip, and the LED chip and the low-voltage linear constant current chip 1 are integrally packaged on the COB substrate in a bare crystal manner; the positive pole of the LED module 2 is connected to an external power supply, and the external power supply is used to provide a low-voltage DC power supply of 12 to 42V for the LED chip; the negative pole of the LED module 2 is connected in series with the low-voltage linear constant current chip 1, and the low-voltage linear constant current chip 1 is used to convert the low-voltage DC power output by the external power supply into a constant current power supply to drive the LED chip to work.

[0024] It should be noted that the external power supply in the present invention is an isolated power supply, and the safe voltage range of the isolated power supply is up to 42V. Specifically, the principle of the low-voltage linear drive is as follows: if the external power supply outputs 36V low-voltage DC power, the rated voltage of the LED chip is 33V. Without the low-voltage linear drive, the current of the LED chip will increase nonlinearly until the voltage of the LED chip reaches 36V or the LED chip burns out due to overcurrent. The function of the low-voltage linear drive is to automatically adjust its own impedance, absorb the remaining 3V voltage, and maintain the current of the LED chip at a constant rated value. The voltage of the LED chip is a multiple of 3V. If there are two LED chips in a string, that is, 6V. To maintain a certain voltage difference and provide a certain working space for the low-voltage linear drive, the output of the constant voltage source must be around 9V. In this case, the conversion efficiency becomes too low. At 6V / 9V, the constant voltage to constant current conversion will lose 33.3% of energy. Furthermore, the output power of the low-voltage DC power supply is preferably 36V, but this is not a limitation.

[0025] Furthermore, the low-voltage linear constant current chip 1 and multiple LED chips in the present invention are all integrally packaged on the COB substrate using a bare die method. Bare die packaging preserves the original COB product's appearance, facilitating production and design, minimizing impact on the customer's existing certification system, and sharing existing lamps, pressure rings, and other supporting materials. Furthermore, because the LED chips are packaged on the COB substrate, they are highly sensitive to the LED chip's temperature, enabling rapid current adjustment to minimize light decay and prevent burnout of the COB light source.

[0026] As can be seen from the above, the constant-voltage-driven COB light source of the present invention incorporates a low-voltage linear constant-current chip 1. This low-voltage linear constant-current chip 1 can convert the constant voltage output of an external power supply into a constant current power supply, and drive the LED chips via a low-voltage linear drive method, further facilitating the centralized use of lamps. Furthermore, the present invention achieves a systematic packaging of bare die with mixed multiple wafer types, effectively reducing heat dissipation resistance and improving heat dissipation efficiency. The installation process is simple, significantly reducing the installation cost of the entire lamp, and facilitating large-scale automated production.

[0027] Preferably, the COB substrate is a metal substrate or a ceramic substrate; the color excited by the LED chip is white light; and the LED chip is a face-up LED chip or a flip-chip LED blue light chip.

[0028] like Figure 2As shown, the VIN terminal of the low-voltage linear constant current chip 1 is connected to the positive terminal of the LED module 2, providing power to the low-voltage linear constant current chip 1 and generating a reference voltage. The reference voltage is a fixed voltage source ranging from 0.01V to 0.6V, and there can be one to three. The reference voltage is selected by the order "Reference Voltage 1" > "Reference Voltage 2" > "Reference Voltage 3". Overvoltage protection and overtemperature protection are switches that select the reference voltage. For example, "Reference Voltage 1" is 0.2V, "Reference Voltage 2" is 0.1V, and "Reference Voltage 3" is 0.05V. The logic function of the operational amplifier OP and MOS transistor in the low-voltage linear constant current chip 1 is that if the voltage at the positive terminal of the operational amplifier is greater than the voltage at the negative terminal, the voltage at the MOS transistor's switch G is increased, allowing more current to flow, resulting in a higher voltage across the resistor. The positive terminal of the resistor is connected to the negative terminal of the operational amplifier. If the voltage at the negative terminal of the operational amplifier is greater than the voltage at the positive terminal, the voltage at the MOS transistor's switch G is reduced, reducing the current flow, ultimately reaching equilibrium, where the voltage at the positive terminal of the operational amplifier equals the voltage at the negative terminal. During normal operation, the op amp's positive terminal is connected to "Reference Voltage 1" (0.2V). Assuming the fixed resistor has a value of 1 ohm, the current is 0.2V / 1R = 200mA. If the temperature rises above a certain set point, the overtemperature protection shuts off the connection to "Reference Voltage 1" and opens "Reference Voltage 2." The op amp's positive terminal is connected to "Reference Voltage 2" (0.1V). The current is 0.1V / 1R = 100mA. Similarly, the current for overvoltage protection is 0.05V / 1R = 50mA.

[0029] Furthermore, the COB substrate may be packaged with one group of light-emitting modules or multiple groups of light-emitting modules with different color temperatures.

[0030] like Figure 3 As shown, in this embodiment, two sets of light-emitting modules with different color temperatures are packaged on the COB substrate 3. In actual application, the positive electrode 33 of the solder pad of the COB substrate 3 is connected to the positive electrode of the external power supply, and the negative electrode 34 of the solder pad is connected to the negative electrode of the external power supply. Two sets of LED modules are placed on the light-emitting surface 31, and two low-voltage linear constant current chips 1 are connected in parallel. The positive electrode 33 of the solder pad is connected to the LED modules and the low-voltage linear constant current chip 1, providing logic power for the LED chips and the low-voltage linear constant current chip 1. The negative electrode of the LED module is also connected to the low-voltage linear constant current chip 1, which controls the current through the LED chip.

[0031] Accordingly, the low-voltage linear constant current chip 1 is fixed to the pads of the COB substrate's dam area 32 and covered with dam glue. During packaging, the low-voltage linear constant current chip 1 is first fixed to the pads of the dam area 32. After die bonding, the dam glue is used to protect the low-voltage linear constant current chip 1, making the final product look exactly like a normal COB light source.

[0032] Preferably, the light emitting surface 31 of the constant voltage driven COB light source is circular, and the shape of the light emitting surface 31 is smoother, which can effectively improve the user experience.

[0033] like Figure 4 As shown, the low-voltage linear constant current chip 1 is provided with a PWM port 11. Therefore, through the reserved PWM port 11, the current of the LED module 2 can be easily controlled, and the dimming and color adjustment functions can be freely realized with strong flexibility.

[0034] Furthermore, the low-voltage linear constant current chip 1 is provided with an overvoltage and overheating protection unit. When the constant voltage driven LED chip is overheated and the input voltage is too high, the current will be reduced to avoid damage to the LED chip, which can effectively improve the reliability of the product, is conducive to the use environment of large-scale commercial lighting fixtures, and has a wide range of market applications.

[0035] As can be seen from the above, the present invention has the following beneficial effects:

[0036] 1. Constant voltage drive COB light source has a built-in low-voltage linear constant current chip. The low-voltage linear constant current chip can convert the constant voltage power output by the external power supply into a constant current power supply, and drive the LED chip through a low-voltage linear drive method, which is more conducive to the centralized use of lamps.

[0037] 2. The low-voltage linear constant current chip is equipped with overvoltage and overheat protection units, which can effectively improve the reliability of the product, is conducive to the use environment of large-scale commercial lighting fixtures, and has a wide range of market applications.

[0038] 3. The low-voltage linear constant current chip is equipped with a PWM port, which can easily realize the dimming function with strong flexibility.

[0039] 4. The bare crystal LED chip and the low-voltage linear constant current chip are integrated and packaged on the COB substrate in a bare crystal manner, realizing the bare crystal system packaging of mixed multiple chip types, which can effectively reduce the heat dissipation thermal resistance, improve the heat dissipation efficiency, simplify the installation process, greatly reduce the installation and cost of the whole lamp, and facilitate large-scale automated production.

[0040] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A constant voltage driven COB light source, characterized in that: It includes a COB substrate and at least one set of light-emitting modules packaged on the COB substrate, each light-emitting module includes a one-to-one corresponding LED module and a low-voltage linear constant current chip; The LED module includes at least one LED chip, and the LED chip and the low-voltage linear constant current chip are integrally packaged on the COB substrate in a bare die manner; The positive electrode of the LED module is connected to an external power supply, and the external power supply is used to provide a low-voltage DC power supply of 12 to 42 V for the LED chip; The cathode of the LED module is connected in series with a low-voltage linear constant current chip, and the low-voltage linear constant current chip is used to convert the low-voltage DC power output by the external power supply into a constant current power supply to drive the LED chip to work; The low-voltage linear constant current chip is provided with a resistor, an operational amplifier and a MOS tube, and the positive electrode of the resistor is connected to the negative electrode of the operational amplifier; when the voltage of the positive electrode of the operational amplifier is greater than the negative electrode voltage, the switch gate voltage of the MOS tube is increased, and the current passing through is increased, so that the voltage across the resistor becomes higher; when the negative electrode voltage of the operational amplifier is greater than the positive electrode voltage, the switch gate voltage of the MOS tube is reduced, and the current passing through is reduced, so that the positive electrode voltage of the operational amplifier is equal to the negative electrode voltage.

2. The constant voltage driven COB light source according to claim 1, wherein: The low-voltage linear constant current chip is fixed on the pad in the dam area of ​​the COB substrate and covered with dam glue.

3. The constant voltage driven COB light source according to claim 1, wherein: The COB substrate is a metal substrate or a ceramic substrate.

4. The constant voltage driven COB light source according to claim 1, wherein: The color excited by the LED chip is white light.

5. The constant voltage driven COB light source according to claim 1, wherein: The LED chip is a face-up LED chip or a flip-chip LED blue light chip.

6. The constant voltage driven COB light source according to claim 1, wherein: A group of light-emitting modules is packaged on the COB substrate.

7. The constant voltage driven COB light source according to claim 1, wherein: The COB substrate is packaged with multiple groups of light-emitting modules with different color temperatures.

8. The constant voltage driven COB light source according to claim 1, wherein: The low-voltage linear constant current chip is provided with an overvoltage and overheat protection unit.

9. The constant voltage driven COB light source according to claim 1, wherein: The low-voltage linear constant current chip is provided with a PWM port.

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