TWI896308B - Solid-state laser with high-efficiency heat sink and the high-efficiency heat sink - Google Patents

Abstract

A solid-state laser with a high-efficiency heat sink comprises: a plurality of solid-state laser elements; and a high-efficiency heat sink comprising a heat-conducting substrate for thermally conductively mounting the solid-state laser elements; at least one heat pipe embedded in the heat-conducting substrate, containing a liquid refrigerant. When the solid-state laser element is in operation, the liquid refrigerant vaporizes, moving the vaporized refrigerant, carrying heat energy, away from the heat-conducting substrate; at least one heat transfer plate disposed behind the heat-conducting substrate; at least one cooling chip thermally conductively bonded to the heat transfer plate on one side, the cooling chip thermally conductively connected to the heat-conducting substrate on the other side; and a plurality of heat sink fins parallel to each other and thermally conductively connected to the heat pipe and away from the heat-conducting substrate.

Description

Solid-state laser with high-efficiency heat sink and the high-efficiency heat sink

The present invention relates to a solid-state laser with a high-efficiency heat sink and the high-efficiency heat sink.

The commonly used vertical cavity surface-emitting laser (VCSEL) not only allows for immediate quality testing and problem resolution during the manufacturing process, thus ensuring controlled product yield, but also allows for high-density, mass-produced production of tens of thousands of VCSELs, resulting in exceptionally high production efficiency. It is particularly well-suited for high-resolution imaging or high-brightness light sources. However, the frequent and high-energy internal reflections within the laser's resonant cavity inevitably lead to high-density light energy loss at the reflective interface, which is converted into heat and accumulated.

Unfortunately, the luminous efficiency of these high-heat-generating components is significantly affected by the ambient operating temperature. For example, if the luminous intensity is measured at 20°C, as the ambient temperature rises, the luminous intensity can rapidly decrease in a near-linear manner, reaching near-zero luminescence at, for example, 70°C. This interference severely limits the practical application of temperature-sensitive solid-state laser components, which possess excellent optical performance. Once the light source's energy consumption reaches hundreds of watts, kilowatts, or even tens of thousands of watts, only about 40-50% of the energy is effectively converted into light, while the remaining 50-60% is converted into heat.

Currently, the most common cooling methods on the market primarily employ air cooling or water cooling. Using air, water, or a refrigerant as a heat transfer medium, heat generated by components is carried away from the component's vicinity and released to a more distant location. Commonly used structures include fans, circulating water pipes, metal heat sinks, heat pipes containing phase-change materials, thermoelectric coolers, and combinations of these. Of course, if energy consumption and size are not a concern, other devices, such as compressors, can also be used.

According to the heat conduction equation, the temperature difference between the high- and low-temperature sides directly affects the efficiency of heat transfer. In other words, once the ambient temperature reaches 40 to 50 degrees Celsius, the temperature near the component itself must be maintained as close to the ideal operating temperature of, for example, 20 degrees Celsius. At the same time, the heat generated by the light source must be efficiently dissipated into the external environment at 40 to 50 degrees Celsius. This efficient heat removal, while avoiding the use of bulky, energy-intensive devices like compressors, presents a complex technical challenge.

One conventional heat sink structure is shown in FIG1 , in which a heat pipe is embedded in a heat-conducting substrate on which a heating element 9 is mounted. The heat generated by the heating element 9 causes the refrigerant in the heat pipe 80 to vaporize, absorbing heat energy through phase change. The vaporized refrigerant expands in volume and thus dissipates within the heat pipe 80 toward the right side of the diagram. A heat sink fin 82 is provided on the right side, and a cooling chip 7 is installed between the heat sink fin 82 and the heat pipe 80, with the cold side facing the heat pipe 80 and the high-temperature side facing the heat sink fin 82, to assist in active heat dissipation. The vaporized refrigerant is condensed back into liquid form by the cooling chip 7, and a portion thereof returns to the heat pipe on the left side through, for example, capillary action within the heat pipe 80. Of course, if the condensation side is located at the top, the liquefied refrigerant can be returned to the vaporization side with the help of gravity. However, since solid-state laser devices 90, such as VCSELs, often do not operate individually, when the heating elements 9 are arranged in an array, for example, the condensed refrigerant will first contact the heating element 93 arranged on the right side as it moves to the left within the heat pipe 80, and will be immediately vaporized. The cooling effect on the heating element 91 on the left side of the figure will rapidly decrease, resulting in uneven actual operating ambient temperatures among the heating elements 91, 92, 93, etc., and differences in the distribution of component aging and degradation depending on the installation location.

Another existing liquid cooling radiator structure is shown in Figure 2. A cooling liquid conduit 84 and 86 are provided on the upper and lower sides of the figure, forming a heat loop. The left and right sides outside the figure are the heat generating element and the heat sink, respectively. Each conduit is thermally connected to a plurality of heat conducting fins 85 and 87, and a cooling chip 7 is thermally installed between each pair of heat conducting fins 85 and 87. This makes the conduit used for cooling cooler and can take away more heat energy from the heat generating element. The heat pipe that carries away heat energy can absorb more heat energy along the way to the outside for removal by the heat sink. However, good thermal conductivity must be maintained between each heat-conducting fin 85 and the ducting tube 84, between the heat-conducting fin 85 and the cooling chip 7, between the cooling chip 7 and the heat-conducting fin 87, and between the heat-conducting fin 87 and the other ducting tube 86. This structure is not only complex, but also becomes increasingly difficult to effectively provide electrical energy for cooling as the number of cooling chips 7 increases. Furthermore, the power loss of this structure is undoubtedly enormous compared to the heat energy removed.

Therefore, maintaining a good operating environment for equipment like solid-state lasers, ensuring they deliver high-efficiency and balanced light emission, and extending their lifespan, particularly by minimizing energy consumption during operation and extending the device's battery life, are key concerns for those in this field.

One objective of the present invention is to provide a solid-state laser with a high-efficiency heat sink. By enabling a structure that selects a heat dissipation mode according to the ambient temperature, the heat removal/energy consumption ratio is improved, thereby reducing the overall operating energy consumption of the solid-state laser.

Another object of the present invention is to provide a solid-state laser with a high-efficiency heat sink. By conducting heat over a large area, the operating environment temperature is evenly distributed, thereby maintaining the overall service life and uniform light emission of the solid-state laser.

Another object of the present invention is to provide a solid-state laser with a high-efficiency heat sink, which can maintain the operation of the solid-state laser in harsh environments through efficient heat dissipation.

Another object of the present invention is to provide a high-efficiency heat sink with selectable operating modes to enhance its flexibility.

Another object of the present invention is to provide a high-efficiency heat sink that reduces overall operating energy consumption through selectable active and passive operating modes.

The solid-state laser with a high-efficiency heat sink disclosed in the above-mentioned case includes: a plurality of solid-state laser components; and a high-efficiency heat sink comprising a thermally conductive substrate for thermally conductively mounting the solid-state laser components; at least one heat pipe embedded in the thermally conductive substrate, containing a liquid refrigerant. When the solid-state laser components are in operation, the liquid refrigerant vaporizes, moving the vaporized refrigerant, carrying heat energy, away from the thermally conductive substrate; at least one heat transfer plate disposed behind the thermally conductive substrate; at least one cooling chip having one side thermally conductively bonded to the heat transfer plate and the other side thermally conductively connected to the thermally conductive substrate; and a plurality of heat sink fins parallel to each other and thermally conductively connected to the heat pipe, away from the thermally conductive substrate. Since the heat pipe embedded in the thermal substrate can be selectively closed, when the ambient temperature is higher than an ideal operating temperature, the refrigerant in the heat pipe can be shut off to effectively prevent the high temperature of the external environment from interfering with the laser operation. On the contrary, when the external environment is at an extremely low temperature, the cooling chip can be used to reversely heat the thermal substrate to quickly reach the appropriate operating temperature. The cooling chip can be switched off to cool the laser passively via the heat pipe and fins. These three operating modes enhance the operational flexibility of the solid-state laser, which is not sensitive to ambient temperature. Furthermore, the choice of active and passive operation, along with simultaneous operation when necessary, improves the overall heat dissipation/energy consumption ratio over extended periods of operation, increasing operational efficiency and effectively extending battery life. Furthermore, when necessary, multiple cooling chips can be stacked to operate continuously in harsh environments, enhancing luminous intensity and extending service life. In particular, the uniform heat dissipation ensures uniform overall luminous intensity. The solid-state laser with a high-efficiency heat sink disclosed in this application solves these problems in one fell swoop.

1, 1', 1", 1''', 1 ⁽⁴⁾ : thermally conductive substrate

10’: Heat transfer plate

12''': Heat transfer unit

2, 2', 2", 2''', 2 ⁽⁴⁾ , 22 ⁽⁴⁾ : heat pipe

20”: Clamping bolt

3: Liquid refrigerant

4, 4', 4''', 7: Cooling chips

5, 5', 5''', 5'''': Heat transfer plate

6, 6', 6'''', 62 ⁽⁴⁾ , 82: heat sink

7''': Connecting bolts

7', 7 ⁽⁴⁾ : Shut-off valve

80: Heat pipe

84, 86: Diversion tube

85, 87: Thermal fins

9, 91, 92, 93: Heating elements

90: Solid-state laser device

Figure 1 is a schematic diagram of a conventional heat sink.

Figure 2 is a schematic diagram of another prior art heat sink.

Figure 3 is a schematic diagram of the first preferred embodiment of the solid-state laser with a high-efficiency heat sink of the present invention.

Figure 4 is a schematic diagram of the second preferred embodiment of the solid-state laser with a high-efficiency heat sink of the present invention.

Figure 5 is a schematic diagram of a third preferred embodiment of the solid-state laser with a high-efficiency heat sink of the present invention.

Figure 6 is a schematic diagram of a fourth preferred embodiment of a solid-state laser with a high-efficiency heat sink according to the present invention.

Figure 7 is a schematic diagram of the fifth preferred embodiment of the solid-state laser with a high-efficiency heat sink of the present invention.

The relevant technical content, features, and functions of this invention will be clearly presented in the following detailed description of the preferred embodiment with reference to the accompanying drawings. The same components in each embodiment are marked with similar reference numbers.

The solid-state laser of the first preferred embodiment of this invention, shown in Figure 3, utilizes multiple solid-state laser elements 90, exemplified by VCSELs, mounted on the right side of a thermally conductive substrate 1. The thermally conductive substrate 1 is divided into two halves, front and rear, each containing a guide groove. When stacked and pressed together, they tightly hold a heat pipe 2 embedded within the thermally conductive substrate 1. Liquid refrigerant 3 is contained within the heat pipe 2. When the solid-state laser elements 90 operate, the liquid refrigerant vaporizes, moving the vaporized refrigerant, carrying heat energy, toward the left side, away from the thermally conductive substrate 1. This effectively and passively removes heat from the thermally conductive substrate 1. In this example, a heat transfer plate 5 is installed behind the left side of the thermally conductive substrate 1. At least one cooling chip 4 is sandwiched between the thermally conductive substrate 1 and the heat transfer plate 5. When the operating environment temperature rises, the cooling chip 4 will begin to operate, driving the heat transfer side attached to the thermally conductive substrate 1 to cool down, while the heat transfer side connected to the heat transfer plate 5 will generate heat. This active heat dissipation can prevent the passive heat dissipation from slowing down or even failing if the external temperature deteriorates, such as if the temperature rises to over 40 degrees Celsius under the scorching sun, causing the VCSEL's light emission to suddenly decrease or even fade away. Furthermore, further to the left of the heat transfer plate 5, away from the heat-conducting base plate 1, are provided a plurality of parallel heat dissipation fins 6 that are thermally connected to the heat pipes 2. Since one end of the heat pipes 2 in this example is embedded in the heat-conducting base plate 1, while the other end is embedded in the heat transfer plate 5, both passive and active heat dissipation from the cooling chip 4 through the heat transfer plate 5 can be dissipated through the heat pipes 2 to the heat dissipation fins 6, ultimately eliminating any dissipation.

Those familiar with the art will readily understand that when the external environment overheats, the number of cooling chips 4 and heat transfer plates 5 can be increased. By stacking each cooling chip like a sandwich, with the side closest to the heat-conducting substrate serving as the cooling side and the side furthest from the substrate serving as the heating side, the temperature can be gradually increased from the rightmost side, closer to the heat-generating element, to the leftmost side, reaching a temperature significantly higher than the ambient temperature. This allows the system's internal heat energy to easily dissipate into the ambient air or external water flow. Furthermore, even heat-generating elements other than solid-state lasers can benefit from active and/or passive multi-layer heat dissipation using the high-efficiency heat sink of the present invention.

Of course, the heat transfer plates don't necessarily need to be arranged parallel to the heat-conducting base. As shown in Figure 4 of the second preferred embodiment of the present invention, when multiple cooling chips 4' are required to operate in coordination, a stacked and cascaded arrangement is not necessary. Alternatively, multiple bent heat transfer plates 10' can be added to the rear side of the heat-conducting base 1'. This allows the cooling chips 4' to conduct heat separately and combine with the bent and extended heat transfer plates 5'. Similarly, through the heat pipes 2', heat energy from both active and passive heat dissipation is transferred to the heat sink fins 6' for output.

Similarly, if the external environment is very cold, the cooling chip can be powered in reverse, with the hot side facing the thermally conductive substrate and the cold side facing away from the thermally conductive substrate. This provides a warm operating environment suitable for starting the solid-state laser device. Once the thermally conductive substrate reaches the ideal operating temperature, the cooling chip can be stopped and passive cooling can be used alone. If the temperature continues to rise and is about to overheat, active and passive cooling can be operated simultaneously. In particular, in this embodiment, a shutoff valve 7' can be provided. When the external environment temperature rises above the ideal operating temperature, for example, when the temperature of the environment in which the system is installed exceeds 70 degrees Celsius, the refrigerant passage within the heat pipe 2' can be shut off, thereby blocking passive heat conduction and preventing the external high temperature from interfering with the solid-state laser's operating environment, retaining only active heat dissipation.

Furthermore, the method of embedding the heat pipe in the thermally conductive substrate is not limited to clamping and tightening. As shown in Figure 5, in the third preferred embodiment of this invention, the edge of the thermally conductive substrate 1" is formed with multiple screw holes. The end of the heat pipe 2" is embedded in the screw holes of the thermally conductive substrate 1", and a tightening bolt 20" is provided to tighten one end of the heat pipe to the thermally conductive substrate 1".

Furthermore, as shown in Figure 6 of the fourth preferred embodiment of this invention, the heat pipe 2'' can also be clamped and thermally conductively bonded to the thermally conductive base 1'' using a snap-fit method. The end of the heat pipe 2''' near the thermally conductive base 1''' is embedded in a clamp, such as a copper clamp. A sloped heat-conducting portion 12'' is formed on the rear side of the thermally conductive base 1'''. The heat-conducting portion 12'' and the rear heat transfer plate 5''' complement each other in shape and are clamped and thermally bonded together by a bolt 7''. This allows the cooling chip 4''', sandwiched between the heat transfer plate 5''' and the heat-conducting portion 12''', to be clamped and thermally conductively bonded to the heat transfer plate 5''' and the heat-conducting portion 12''' on both sides, respectively.

Furthermore, when the operating environment is bad, such as in an outdoor environment with a huge temperature variation range, the active heat dissipation heat pipe 22 ⁽⁴⁾ can be directly separated as shown in the fifth preferred embodiment of the present case in FIG7 , so that the passive heat dissipation heat pipe 2 ⁽⁴⁾ and the passive heat dissipation heat fin 6 ⁽⁴⁾ can operate independently, and when the external environment temperature is measured to have exceeded the operating temperature range, the shut-off valve 7 ⁽⁴⁾ can be directly closed; in contrast, the active heat dissipation heat pipe 22 ⁽⁴⁾ and the heat dissipation fin 62 ⁽⁴⁾ are provided behind the heat transfer plate 5 ⁽⁴⁾ , and active heat dissipation is performed independently, using two different paths to effectively conduct the heat energy transferred from the heat transfer substrate 1 ⁽⁴⁾ .

Through the disclosure of this invention, solid-state lasers using high-efficiency heat sinks can not only independently select active and passive cooling modes, but also reverse the active cooling mode to increase heat, or combine the two modes for synergistic operation when environmental conditions are appropriate. This effectively enhances operational flexibility and, by taking into account long-term environmental changes, effectively conserves energy consumed by heat dissipation, thereby increasing the endurance of independently operated solid-state laser devices and effectively resolving the aforementioned technical challenges. Of course, the above disclosure is intended to facilitate understanding of the present invention. Equivalent effects and other variations and modifications based on the present structure are all within the scope of the patent.

1: Thermally conductive substrate

2: Heat pipe

3: Liquid refrigerant

4: Cooling chip

5: Heat transfer plate

6: Heat sink fins

90: Solid-state laser device

Claims (8)

A solid-state laser with a high-efficiency heat sink comprises: a plurality of solid-state laser elements; and a high-efficiency heat sink comprising a heat-conducting substrate for thermally conductively mounting the solid-state laser elements; at least one heat pipe embedded in the heat-conducting substrate, containing a liquid refrigerant. When the solid-state laser element is in operation, the liquid refrigerant vaporizes, moving the vaporized refrigerant, carrying heat energy, away from the heat-conducting substrate; at least one heat transfer plate disposed behind the heat-conducting substrate; at least one cooling chip thermally conductively bonded on one side to the heat transfer plate, the other side of the cooling chip thermally conductively bonded to the heat-conducting substrate; a plurality of heat sink fins parallel to each other and thermally conductively connected to the heat pipe away from the heat-conducting substrate; and the other end of the heat pipe away from the heat-conducting substrate is thermally conductively bonded to the heat transfer plate. In the solid-state laser with a high-efficiency heat sink as described in claim 1, the thermally conductive substrate comprises two half-pieces, and at least one guide groove for tightly clamping the heat pipe is formed between the two half-pieces. In the solid-state laser with a high-efficiency heat sink as described in claim 1, the thermally conductive substrate further includes a plurality of bent heat transfer sheets for bonding to the other side of the cooling chip. In the solid-state laser with a high-efficiency heat sink as described in claim 1, the thermally conductive substrate is formed with a plurality of screw holes, and the ends of the heat pipes connected to the thermally conductive plate are tightened and engaged into the screw holes by tightening bolts corresponding to the screw holes. In the solid-state laser with a high-efficiency heat sink as described in claim 1, the heat pipe is clamped and tightly bonded to the heat-conducting substrate. The solid-state laser with a high-efficiency heat sink as described in claim 1, 2, 3, 4, or 5 further includes a shutoff valve for shutting off the movement of the refrigerant in the heat pipe. A high-efficiency heat sink comprises a heat-conducting substrate for mounting at least one heat-generating element; at least one heat-conducting tube embedded in the heat-conducting substrate, containing a liquid refrigerant. When the heat-generating element operates, the liquid refrigerant vaporizes, moving the vaporized refrigerant, carrying heat energy, away from the heat-conducting substrate; at least one heat transfer plate disposed behind the heat-conducting substrate; at least one cooling chip thermally bonded on one side to the heat transfer plate, the other side of the cooling chip thermally bonded to the heat-conducting substrate; a plurality of heat-dissipating fins parallel to each other and thermally connected to the heat-conducting tube away from the heat-conducting substrate; and the other end of the heat-conducting tube away from the heat-conducting substrate is thermally bonded to the heat transfer plate. The high-efficiency heat sink as described in claim 7 further includes a shutoff valve for shutting off the movement of the refrigerant in the heat transfer pipe.