Acoustic camera with integrated housing and passive cooling structure

Abstract

The passive heat sink for an acoustic camera with a microphone array and an on-board processor is improved. The on-board processor dissipates heat using a heat sink member in a sealed housing and conducts heat to a heat dissipation surface of the housing. Preferably, the heat sink member is a spring member that has a dual function of providing mechanical force to ensure good thermal contact to the on-board processor and providing thermal conduction to the heat dissipation surface. A single housing may house both the on-board processor and the microphone array. Alternatively, the housing may have two parts, a first part surrounding the microphone array and a second part surrounding the on-board processor.

Description

Technical Field

[0001] The present invention relates to a heat sink structure of an acoustic camera.

Background Art

[0002] Over the past few decades, noise pollution has become an increasingly serious problem. In order to reduce noise emissions, local governments and factories have installed acoustic noise sensors to monitor noise sources and gain insights into noise sources. Acoustic cameras can meet their needs not only from an environmental perspective but also from an industrial perspective. An acoustic camera may include an array of microphones and may or may not be combined with a visual image capture device or camera. Fixed acoustic cameras that utilize long-distance beamforming (BF) for acoustic imaging and for monitoring ambient volume are commercially available.

[0003] Acoustic cameras are increasingly being used as multifunctional smart IoT (Internet of Things), handheld or mobile devices. For example, a 64-channel MEMS microphone array of 16×16 centimeters may be installed on a street lamp post above an intersection. The signal processing unit and the computing unit can be integrated not only with the power unit and connections but also within the same small form factor device. Due to privacy protection laws and data protection laws, in order to minimize the risk of data theft and other risks related to data protection and privacy, it is desirable that raw data be processed as close as possible to the sensor array. Usually, only the processed and secure anonymized data is communicated outside the device. Therefore, very complex and / or computationally intensive processing is executed on an on-board processor. Also, the reason for being close to the sensor array and on-board computing is due to the limitation of the data bandwidth.

[0004] Performing acoustic beamforming, spectral analysis, acoustic anomaly detection, acoustic event localization, signal classification (using artificial intelligence acoustic modeling), or other computationally intensive tasks requires considerable onboard processing power. Currently, this is handled not only by the central processing unit but also by graphics processing units (CPU and GPU), ASICs, or FPGAs. Performing this type of onboard processing in a small form factor device requires dissipating a large amount of power as heat into the environment. If this is not done correctly, the computing unit may cease to function, potentially leading to a complete loss of device functionality and, consequently, a high likelihood of data loss.

[0005] For standard applications, metal cooling elements with ribs to maximize contact area with the environment (often air) are used for cooling. High-performance onboard computers often require active cooling solutions, including water cooling and ventilators. For acoustic camera functions, the use of ventilation devices or pumps that may generate noise must be prohibited or at least limited. Therefore, passive solutions are preferred when edge computing is involved. Furthermore, active cooling solutions limit the continuity of on-site monitoring functions, while acoustic monitoring functions often require multi-year continuity. This results in additional costs and maintenance requirements. In other words, establishing passive cooling can yield significant and sustained benefits.

[0006] Therefore, providing an improved passive heatsink to an acoustic camera with substantially onboard processing would represent an advance in the field. [Overview of the Initiative] [Means for solving the problem]

[0007] This research provides a device that incorporates a microphone array within the same housing as an advanced processing unit or onboard computer. Due to constraints such as industrial or urban applications and installation methods in infrastructure, the size and weight of the housing may be limited. Lightweight design, ingress protection, ease of installation, and robustness are important characteristics that must be optimized for the device to be accepted in its application field.

[0008] Therefore, when heat dissipation is properly implemented while considering the important characteristics described above, an onboard computer can be connected to a heatsink that is essential to the external design of the device. Since the onboard computer is located inside the housing (or internal space), a solution has been found to efficiently transfer heat from the compute unit to the outer housing through a metal heat spreader and part of the internal structure. In this case, the metal heat dissipation component has a large effective area integrated with the outer housing of the product (see example below). To maximize the effective area for heat dissipation, the solution may or may not include ribs. On the other hand, such options may be limited by visual and functional design considerations. For example, in dusty environments, channels between ribs may become clogged. Also, a sealed exterior design of the metal casing improves protection against foreign matter ingress.

[0009] Furthermore, the internal structure of the metal heat dissipation section of the device may be configured to function as a mechanical spring. This is an important feature not only for heat dissipation capacity but also for the robustness of the device. The internal spring (leaf spring) applies small pressure to the heat spreader component that is in direct contact with high-power components on the outside of the computer chip. If the tension is not applied correctly throughout, overheating may cause part of the chip to fail. [Brief explanation of the drawing]

[0010] [Figure 1A] This figure schematically shows a first exemplary embodiment of the present invention. [Figure 1B] This figure schematically illustrates a second exemplary embodiment of the present invention. [Figure 2A] This figure shows a detailed example of the embodiment shown in Figure 1B. [Figure 2B] This figure shows a detailed example of the embodiment shown in Figure 1B. [Figure 2C] This figure shows a detailed example of the embodiment shown in Figure 1B. [Figure 3A] These are simplified diagrams showing the heat sink components of the examples in Figures 2A to 2C. [Figure 3B] These are simplified diagrams showing the heat sink components of the examples in Figures 2A to 2C. [Figure 3C] These are simplified diagrams showing the heat sink components of the examples in Figures 2A to 2C. [Figure 3D] These are simplified diagrams showing the heat sink components of the examples in Figures 2A to 2C. [Figure 4A] This figure schematically illustrates a third exemplary embodiment of the present invention. [Figure 4B] This figure schematically shows a fourth exemplary embodiment of the present invention. [Figure 5A] This is a simplified diagram showing a second example of an enclosure, as shown in Figure 4B. [Figure 5B] This is a simplified diagram showing a second example of an enclosure, as shown in Figure 4B. [Figure 5C] This is a simplified diagram showing a second example of an enclosure, as shown in Figure 4B. [Figure 5D] This is a simplified diagram showing a second example of an enclosure, as shown in Figure 4B. [Figure 5E] This is a side view showing a handheld acoustic camera with a housing comprising two parts, similar to Figure 4B, and showing the back of the housing attached to the auxiliary unit. [Modes for carrying out the invention]

[0011] Figure 1A schematically shows a first exemplary embodiment of the present invention. The example shown here is an acoustic camera comprising a housing 102 defining an internal space, an acoustic microphone array 104 positioned on a first surface 102a of the housing and facing away from the internal space, an onboard processor 106 positioned in the internal space and electrically connected to the acoustic microphone array 104 (via a connection schematically indicated as reference numeral 108), and a heat sink member 110 that thermally contacts the onboard processor 106. The heat sink member 110 is configured to conduct heat from the onboard processor 106 to a heat dissipation surface 102b of the housing that is different from the first surface 102a. Here, this heat conduction is schematically shown by block arrow 112.

[0012] Figure 1B schematically shows a second exemplary embodiment of the present invention, which includes several selectively adoptable characteristic configurations.

[0013] A first selectively adoptable characteristic configuration is a heat transfer block 114 configured to at least partially fill the space between the heat sink member 110 and the onboard processor 106.

[0014] A first selectively adoptable characteristic configuration is an improvement in thermal contact between the heat sink member and the onboard processor using spring tension. This is shown in Figure 1B as a device comprising a spring member 116 configured to provide a mechanical force (indicated by the solid black block arrow) that causes the heat sink member 110 to thermally contact the onboard processor 106 (via the heat transfer block 114).

[0015] However, in many cases, it is preferable that the heat sink member 110 itself be configured as a mechanical spring that applies the contact force necessary for good thermal contact. In this case, instead of providing a separate spring member 116 as in the example of FIG. 1B, the spring member (which is part of the heat sink member) is configured to thermally contact the on-board processor and thereby conduct heat from the on-board processor to the heat dissipation surface. At this time, the reference numeral 110 shown in FIG. 1A or FIG. 1B is both a heat sink member and a spring member.

[0016] Figures 2A - 2C show detailed examples of the embodiment of FIG. 1B including some additional optionally adoptable characteristic configurations. The acoustic camera may include one or more heat sink fins 202 (FIG. 2A) disposed on the heat dissipation surface 102b. The housing 102 may be square or rectangular, in which case it has four corners. The housing may include a front wall 204, a rear wall 206 opposite the front wall 204, and side walls 208, and the side walls 208 connect the front wall 204 to the rear wall 206, thereby enclosing the internal space (see FIG. 2B). The on-board processor 106 may be configured as a system-on-module 106a including at least one integrated circuit die 106b, and the die 106b directly contacts a heat transfer block 114 as shown in FIG. 2C. Here, the die 106b is not a bare chip but is packaged in a package that provides a good thermal contact surface for heat transfer as is known in the art. In this embodiment, the heat dissipation surface 102b of the housing 102 is provided on the side walls 208.

[0017] Figures 3A - 3D are some schematic views showing the heat sink members of the examples of FIGS. 2A - 2C. FIG. 3A is an isometric projection view, and FIGS. 3B - 3D are three corresponding three-sided views. In this embodiment, the spring member 110 is connected to the heat dissipation surfaces at the four corners of the housing. The optionally adoptable characteristic configurations shown in these figures include the above-described heat sink fins 202, circuit board connection points 302, mechanical interfaces 304 (such as for attachment to a tripod, etc.), and feed-throughs 306 for power and data.

[0018] In the case of the example of FIG. 3A, it has been calculated that a total of 15 watts of heat can be dissipated from the on-board processor to the heat dissipation surface of the acoustic camera without significantly heating the air inside the housing from the analysis modeling and verification of the durability test. Under the condition of the maximum performance of the on-board processor, the temperature difference between the temperature of the processor and the outer surface of the radiator does not exceed 11 degrees Celsius, and the steady-state temperature is reached after 16 hours. The core temperature of the processor remained well below the maximum rated value. When directly comparing the above-described heat dissipation outer housing component with a modified example of a plastic outer housing equipped with the same on-board processor, the core of the processor reached the temperature limit within 3 minutes. Based on the maximum value of the power consumption of the processor unit, the width and thickness of the outer housing area and the internal heat sink member / heat spreader for heat dissipation may be determined and designed.

[0019] Furthermore, it is preferable that the design of the heat sink member be such that all designs can be manufactured from a metal forming process. This reduces the assembly procedure during the manufacture of the acoustic camera, enabling mass production and cost reduction. Furthermore, in the case of a large processor unit with high heat dissipation, the cooling capacity of the assembly may be improved by arranging or inserting a material with high thermal conductivity into the mold.

[0020] In the example described above, both the on-board processor and the microphone array are housed in one housing. In other embodiments, the housing has two parts, namely, a first part including the acoustic microphone array and a second part including the on-board processor. FIG. 4A is a diagram schematically showing a first example of this configuration. Here, reference numeral 402 refers to the first part of the housing 102, and reference numeral 404 refers to the second part of the housing 102. The electrical connection 108 between the microphone array 104 and the on-board processor is made via the contact 406, which may be done by conventional electrical contact technology. The heat sink of the on-board processor 106 shown in this example is as described above.

[0021] One of the advantages of this configuration is that the microphone array can be isolated from the rest of the unit. This makes it easy to create a configuration, as shown in Figure 4B, where the microphone array 104 extends laterally and is larger than the rest of the camera, and only the first part 402 of the housing needs to be enlarged accordingly. This separation has two advantages. A larger microphone array tends to improve low-frequency sound performance, and keeping the second part 404 smaller can also improve heat dissipation. However, increasing the size of the second part 404 of the housing would require additional thermal verification, at least in the detailed design phase, and if the resulting increased heat transfer path length becomes a problem, it could objectively make designing for larger sizes difficult.

[0022] Figures 5A–5D are several simplified diagrams illustrating an exemplary second part 404. Figure 5A is an isometric projection, and Figures 5B–5D are the three corresponding orthographic views. Here, reference numeral 502 indicates an interface for mating with an auxiliary unit, which will be described in relation to Figure 5E.

[0023] Figure 5E is a side view showing a handheld acoustic camera having a two-part housing, similar to Figure 4B, where the rear of the housing is attached to an auxiliary unit. Here, reference numerals 402 and 404 refer to the first and second parts of the housing described above, respectively. The auxiliary unit 504 is connected to the second part 404 of the housing.

[0024] The auxiliary unit 504 may include various components, such as a pistol grip 510 for handheld operation, a battery compartment 506 configured to power an onboard processor and an acoustic microphone array, and a display 508 that provides a visual readout to the acoustic camera. The display 508 may be a touchscreen display.

Claims

1. A casing that defines the internal space, An acoustic microphone array is arranged on the first surface of the housing and facing away from the internal space, An onboard processor, arranged in the internal space and electrically connected to the acoustic microphone array, The heat sink member is configured to thermally contact the onboard processor and conduct heat from the onboard processor to a heat dissipation surface of the housing that is different from the first surface. The heat sink member is formed as a single component and functions as an acoustic camera that conducts heat from the onboard processor to the heat dissipation surface and, by elastic deformation, provides a biasing force that causes the heat sink member to thermally contact the onboard processor.

2. The acoustic camera according to claim 1, further comprising one or more heat sink fins arranged on the heat dissipation surface.

3. The acoustic camera according to claim 1, wherein the housing is square or rectangular and has four corners.

4. The acoustic camera according to claim 3, wherein the spring member is in contact with the heat dissipation surface at the four corners of the housing.

5. The acoustic camera according to claim 1, further comprising a heat transfer block configured to at least partially fill the space between the heat sink member and the onboard processor.

6. The housing includes a front wall, a rear wall facing the front wall, and side walls. The acoustic camera according to claim 1, wherein the side wall is configured to define the internal space by connecting the front wall to the rear wall.

7. The acoustic camera according to claim 6, wherein the heat dissipation surface of the housing is provided on the side wall.

8. The aforementioned enclosure is A first portion including the aforementioned acoustic microphone array, The acoustic camera according to claim 1, further comprising a second part including the onboard processor.

9. The acoustic camera according to claim 8, further comprising an auxiliary unit connected to the second portion of the housing.

10. The acoustic camera according to claim 9, wherein the auxiliary unit includes one or more selected from the group including a pistol grip for handheld operation, a battery compartment configured to supply power to the onboard processor and the acoustic microphone array, and a display that provides a visual readout to the acoustic camera.

11. The acoustic camera according to claim 10, wherein the display is a touchscreen display.

Images