WO2009139765A1

WO2009139765A1 - Sensor assembly with optimized response time

Info

Publication number: WO2009139765A1
Application number: PCT/US2008/063442
Authority: WO
Inventors: David A. Moore; Allen T. Morrison; Hoang Thanh Nguyen; Chris F. Felcman
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2008-05-12
Filing date: 2008-05-12
Publication date: 2009-11-19

Abstract

An apparatus and system for optimized response time, the apparatus comprising a first housing; a second housing; wherein the first housing and the second housing are coupled together to form an enclosure, at least one of the first housing and the second housing comprising at least one ventilation opening therein to allow air to circulate through the at least one of the first housing and second housing; a printed circuit board enclosed within the enclosure, wherein the printed circuit board is mounted on at least one elevated pedestal; and at least one environmental sensor centrally mounted on the printed circuit board in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one environmental sensor includes at least one cut-out portion of the printed circuit board.

Description

SENSOR ASSEMBLYWITH OPTIMIZED RESPONSE TIME

FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of sensor assemblies. More particularly, the present invention relates to a specialized configuration that optimizes the response time of at least one environmental sensor located within a sensor assembly.

BACKGROUND OF THE INVENTION

[0002] This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in the application and is not admitted to be prior art by inclusion in this section.

[0003] The present invention relates generally to the field of environmental sensor assemblies. Environmental sensors are used in a variety of systems, environments, applications, and devices. These environmental sensors are generally used to measure physical quantities and convert the measured values into signals which can be subsequently used in various processes and/or algorithms. While a plurality of different sensor assemblies are currently available and being used in a variety of different applications, sensor configurations have been problematic and have led to inaccuracies and delays in the data collection and the reporting function of the sensors. Moreover, previous configurations for temperature sensor assemblies produced delays in the sensor settling on temperature readings. As one can imagine, such delays can impact other processes or algorithms that require the sensor measurements in order to conduct their own respective processes. [0004] As such, there is a need for an environmental sensor assembly designed in a manner to provide accurate measurements, optimized response time, and minimal interference.

SUMMARY OF THE INVENTION

[0005] An apparatus for optimized sensor response time, comprising in one embodiment, a first housing; a second housing, wherein the first housing and the second housing are coupled together to form an enclosure, at least one of the first housing and the second housing comprising at least one ventilation opening therein to allow air to circulate through the at least one of the first housing and second housing; a printed circuit board enclosed within the enclosure, wherein the printed circuit board is mounted on at least one elevated pedestal; and at least one environmental sensor centrally mounted on the printed circuit board in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one environmental sensor includes at least one cut-out portion of the printed circuit board. [0006] In a further embodiment, a system for optimized sensor response time is disclosed, the system comprising: a computing device; a casing comprising a plurality of sensor assemblies interconnected via communication cables, wherein the casing is attached to the computing device; the sensor assembly comprising: a first housing; a second housing, wherein the first housing and the second housing are coupled together to form an enclosure, at least one of the first housing and the second housing comprising at least one ventilation opening therein to allow air to circulate through the at least one of the first housing and second housing; a printed circuit board enclosed within the enclosure, wherein the printed circuit board is mounted on at least one elevated pedestal; and at least one environmental sensor centrally mounted on the printed circuit board in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one environmental sensor includes at least one cut-out portion of the printed circuit board. [0007] In yet another embodiment, a system for optimized sensor response time is disclosed, the system comprising: a first housing means; a second housing means, wherein the first housing means and the second housing means are coupled together to form an enclosure, at least one of the first housing means and the second housing means comprising at least one ventilation means to allow air to circulate through the at least one of the first housing means and second housing means; means for mounting at least one sensing means, wherein the at least one sensing means is mounted centrally on the means for mounting in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one sensing means includes at least one cut-out portion of the mounting means. [0008] These and other advantages and features of various embodiments of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the several drawings described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is a 3-D perspective drawing of an embodiment of the enclosure from a first angle.

[0010] Fig. 2 is a 3-D perspective drawing of an embodiment of the enclosure from a second angle.

[0011] Fig. 3 is a schematic representation of the circuitry which may be included in various embodiments of the enclosure.

[0012] Fig. 4 is a schematic representation of the circuitry including a memory device which may be included in various embodiments of the enclosure.

[0013] Fig. 5 is a 3-D perspective drawing of an embodiment of the enclosure with ventilation openings in the upper and lower housings.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0014] The invention is described below with reference to drawings. There drawings illustrate certain details of specific embodiments that implement the systems and apparatus of the present invention. However, describing the invention with drawings should not be construed as imposing, on the invention, any limitations that may be present in the drawings. The present invention contemplates both apparatuses and systems.

[0015] The present invention combines influences from various design elements in order to produce optimized response time from an environmental sensor. In other words, the synergies of design elements within the present invention create an optimal environment wherein a sensor can provide rapid and accurate measurements. In order to achieve the accurate and rapid measurements, the present invention contemplates an assembly that enables an environmental sensor to be surrounded by air that is representative of the actual outside air. In addition, the present invention contemplates an assembly that is configured to isolate an environmental sensor from outside influences to thereby reduce inaccuracies and enable the environmental sensor to settle on an accurate measurement in a short period of time. These and other innovative improvements that enable optimal response time from an environmental sensor are discussed in detail below with reference to various figures. [0016] Fig. 1 shows an exemplary embodiment of the present invention, wherein the sensor assembly 100 is configured to provide optimized response time. In one embodiment, the sensor assembly 100 is one of a plurality of sensor assemblies 100 that are interconnected via cables interconnects 180 to form a chain of sensor assemblies. However, such a configuration should not be seen as limiting because other possible configurations are also contemplated in different embodiments. Each sensor assembly 100 comprises a first housing 110 and a second housing 120. The first 110 housing and the second 120 housing are coupled together to form an enclosure wherein a cable interconnect 180 may extend from each of the ends of the sensor assembly 100 to enable the sensor assemblies to send and receive data, power, and other types of electrical signals. Within the enclosure lies a printed circuit board (PCB) 140 and at least one environmental sensor (depicted in Fig. 2) attached to the PCB 140. As discussed in greater detail below, the environmental sensor may be positioned between two cut-out portions 170 of PCB to isolate the environmental sensor on a narrow portion of PCB. In addition, and as also discussed in greater detail below, the first housing and/or second housing may include a first 131 and a second 132 interior wall to further isolate the environmental sensor from outside influences. Furthermore, ventilation openings 130 are disposed on the first housing 1 10 and/or second housing 120 housing to enable air circulation. As will be made clear from the description below, each of these design elements and PCB layout considerations operate to form an enclosure that enables an environmental sensor to provide optimized response time.

[0017] With regard to the housing, Fig. 1 depicts an embodiment wherein ventilation openings 130 are present in the central portion of the first housing 110. These ventilation openings 130 allows air to circulate through the first housing 110, thereby allowing for the environmental sensor to be in constant contact with the surrounding air. In addition to enabling contact with air, such a configuration allows the air to flow through the enclosure and therefore enables the sensor to measure surrounding air that is representative of the air that is outside the enclosure. In other words, the sensor is not measuring "stagnant" air within the enclosure or air that has been tainted by long term exposure to influences within the enclosure. Accordingly, the sensor is able accurately measure and provide accurate readings to the other processes that are representative of the atmosphere that is actually proximate to the sensor assembly 100. In one embodiment, the at least one ventilation openings 130 comprise an area greater than the area of the at least one environmental sensor. [0018] While Fig. 1 depicts ventilation openings only in the first housing 110, it is contemplated that the ventilation openings could alternatively be situated in the first housing 110, second housing 120, or both (as depicted in Fig. 5). If the ventilation openings are present in second housing 120, air circulation is enabled beneath the PCB. If the ventilation openings are situated in both the first housing 110 and the second housing 120, such a configuration provides a "full vent," wherein air is allowed to circulate through both the first housing and the second housing. Therefore, air circulates in the open volume above and below the PCB in this embodiment. [0019] In addition to different locations for the ventilation openings, it is also contemplated that the design of the ventilation openings could differ from the openings depicted in Fig. 1. For example, while Fig. 1 depicts a ventilation opening that comprises seven narrow slits spanning the width of the first housing, it is also contemplated that various other ventilation configurations may be implemented within the housing. Such ventilation openings could include vertical and/or horizontal openings. In addition, such ventilation openings could include one or more openings on one or more sides of the first, second, or both housings. Moreover, it is contemplated that the ventilation openings can differ in size and shape. Furthermore, porous coverings, such as mesh, can cover the openings to enable air to enter without the entrance of dust or other undesirable particles.

[0020] Furthermore, while Fig. 1 depicts ventilation openings located in the central portion of the housing. It is also contemplated that the ventilation openings be located in other areas of the housing. However, in some embodiments, the ventilation openings are located proximate to the environmental sensor. [0021] It is noted that all of the above configurations must balance other considerations such as protection of the PCB and the associated components against the need for ventilation. In one configuration, an optimum balance is achieved between the number of necessary ventilation openings and the protection of internal components from negatives such as electrostatic discharge or reduced structural integrity.

[0022] Furthermore, with regard to each of the housings, sensor isolation and improved response time are achieved by the use of interior walls. As depicted in Fig. 1 , a first interior wall 131 and a second interior wall 132 are positioned on opposite ends of the ventilation opening 130. Each interior wall can be molded within the housing or optionally included as separate pieces that are coupled to one of the housings or the PCB. Each interior wall is optimally positioned to isolate the environmental sensor from the influences of other components located within the sensor assembly 100. For example, heat producing components that emit heat are isolated from the sensor by the interior walls. As such, inaccuracies due to these heat producing components in the sensor measurements are minimized by isolating the environmental sensor via the first interior wall 131 and the second interior wall 132. In one embodiment, a first and second interior walls may be located in the lower housing 120. As such, interior walls may be present in the first housing 110, second housing 120, or both housings. [0023] As discussed above, the first housing 110 and the second housing 120 are coupled together to form an enclosure. The first housing and the second housing may be coupled via threaded screws. However, various other well-known coupling mechanisms, such as adhesive or snap-fit, are also contemplated. Furthermore, each of the first 110 and second 120 housings may be comprised of a synthetic material such as plastic material. However, the housings are not limited to plastic materials. It is contemplated that each housing can be comprised of other materials such as metals, fiberglass, etc.

[0024] Within the enclosure, the PCB 140 may be mounted on at least one elevated pedestals (depicted in Fig. 2). Each elevated pedestal protrudes from the second housing 120. In addition, each elevated pedestal protrudes to at least a height that enables the pedestal to elevate the PCB above the second housing thereby creating an open space or volume beneath the PCB. Accordingly, the PCB is elevated within the enclosure thereby creating an open volume or space above and below the PCB.

[0025] At opposite ends of the PCB 140 are connectors 190 that may be connected to a 4-conductor electrical bus. However, other types of connectors are also contemplated. The 4-conductor electrical bus comprises the following signals: ground, +5v power, +3.3v power, and a 1-wire signal. The connector 140 is coupled to the cable interconnects 180 via known coupling methods.

[0026] Fig. 2 provides a depiction of the sensor assembly 200 from a different angle that more clearly depicts inventive features of the sensor assembly 200. As discussed, the sensor assembly 200 may be one of a plurality of sensor assemblies interconnected via connectors 290 and cable interconnects 280. Furthermore, as also discussed above, the sensor assembly 200 is configured to provide optimized response time. The assembly comprises a first housing 210 and a second housing 220. The first 210 housing and the second 220 housing are coupled together to form an enclosure. Within the enclosure is a printed circuit board (PCB) 240 mounted on elevated pedestals 250 with an attached environmental sensor 260 mounted to the PCB. [0027] As more clearly shown from this perspective, the PCB 240 is populated with a plurality of components. The components may be mounted using surface mount technology. However, components may also be mounted using other well-known mounting techniques such as through-hole, ball grid array, and the like. One such component is an environmental sensor 260. The environmental sensor 260 may be mounted centrally on the PCB. However, the environmental sensor 260 can optionally be mounted in other locations on the PCB 240 as long as the location is proximate to the ventilation openings 230. As discussed above, the environmental sensor 260 is in communication with the surrounding ambient air and may be used to measure surrounding air temperature. This temperature measurement can be in Fahrenheit, Celsius, or both. However, in other embodiments, the environmental sensor 260 measures humidity, ambient air pressure, vibrations, acoustics, radiation, electrical fields, light, and the like.

[0028] Furthermore, the design and layout of the PCB itself contains features that enable the environmental sensor 260 to provide accurate and rapid response time. Moreover, the design and layout of the PCB contains features that isolate the sensor from the influences of other components. One such feature is the at least one cut-out portion 270 of the PCB located in the periphery of the environmental sensor. In one embodiment, two cut-out portions are located on opposite sides of the environmental sensor 260 thereby isolating the environmental sensor on a narrow isthmus. Optionally, more than two cut-out portions 270 of PCB 240 can surround the sensor 260. In one embodiment, at least one cut-out portion of the printed circuit board comprises an area at least twice the area of the at least one environmental sensor footprint.

[0029] In addition, and as discussed above, isolation of the environmental sensor is further achieved by a first interior wall 231 and a second interior wall 232. The first interior wall 231 and the second interior wall 232 are positioned on opposite ends of the ventilation opening 230 in the first housing and/or second housing. Each interior wall is optimally positioned to isolate the environmental sensor 260 from outside influences. As such, inaccuracies in the sensor reading are minimized by isolating the environmental sensor from power dissipation elsewhere on the PCB. [0030] Furthermore, in order to further isolate the sensor from outside influences and to enable the most accurate measurement, no heat producing components, such as light emitting diodes (LED), resistors, diodes, capacitors, and the like, are mounted between the first and second interior walls. Such a configuration enables the environmental sensor 260 reading to not be distorted by heat dissipated from proximate components. Accordingly, the air surrounding the environmental sensor is consistent with the air outside of the enclosure. Such a configuration further enables the environmental sensor to settle on a temperature reading more rapidly and thereby provide readings to other processes or components. Alternatively, the present invention also contemplates mounting only essential heat producing components between the first and second interior walls. Mounting essential heat producing elements within the interior walls may be for a different type of optimization. For instance, sensors for other quantities may require a different configuration in which heat producing components are deliberately placed within the interior walls to, for example, maintain a suitable temperature.

[0031] Fig. 3 shows an exemplary embodiment of the printed circuit board

340 including the optimized response time design considerations. Specifically, the environmental sensor 360 is mounted on the printed circuit board 300 in between a first cut-out portion of PCB 370 and a second cut-out portion of PCB 372. The first cut-out portion of PCB 370 and a second cut-out portion of PCB 372 reduce the material surrounding the sensor 360 and thereby allow for quicker response by reducing the mass of the material in intimate contact with the sensor 360. Since the sensor 360 reads its own internal temperature, it is important that that temperature is influenced more by the surrounding air, than by the temperature of the PCB. Accordingly, the cut-out portions reduce the amount of PCB material surrounding the sensor 360, and also isolate the mounting surface from other areas of the PCB. The cut-out portions also increase the PCB surface area in contact with the air, therefore causing PCB temperature near the sensor 360 to track air temperature more closely. Moreover, the cut-out portions also allow for air exchange between the two halves of the housing. Accordingly, the sensor is isolated on narrow portion of circuit board to reduce the thermal mass and enable the sensor to react more quickly to changes in the surrounding air temperature.

[0032] Furthermore, heat producing elements are removed from the surface area proximal to the PCB. For example, a first heat producing resistor 374 is mounted on an opposite end of the PCB 300 with regard to the sensor 360. Specifically, the first heat producing resistor 374 is mounted proximate to one of the connectors 390. In addition, the value of the heat producing resistors is adjusted to minimize heat production. Also, the present invention minimizes the size of the copper traces 376 in the area of the sensor 360, thereby reducing the thermal conductivity within the board, and therefore reducing the tendency for the sensor to track PCB temperature rather than air temperature.

[0033] Fig. 4 shows a close up view of another embodiment of the printed circuit board assembly 400. Similar to Fig. 3, this embodiment includes at least the PCB 440, a first cut-out portion 470, a second cut-out portion 472, an environmental sensor 460, minimized traces 476, a connector 490, and a heat producing resistor 474 mounted proximal to the connector. In addition, this embodiment includes an optional memory 478 electronically coupled to the environmental sensor 460. In one embodiment, the memory 478 is an EEPROM memory for generic input/output and storage purposes, however, other well-known memory types are also contemplated. [0034] Fig. 5 shows a "full vent" embodiment of the enclosure 500 as previously discussed. As depicted in Fig. 5, a first ventilation opening 530 is situated in the first housing 510 and a second ventilation opening 535 is situated in the second housing 520. Such a configuration provides a "full vent," wherein air is allowed to circulate through both the first housing 510 and the second housing 520. Therefore, air circulates in the open volume above and below the PCB in this embodiment. [0035] Thus, the present invention takes advantage of the synergies of various sensor assembly design elements in order to enable a sensor to output accurate and rapid measurements. The ventilation opening improvements, interiors walls, PCB cut-outs, and component layout are a few of the design elements that operate to produce an optimal environment for the sensor. [0036] In one embodiment, the sensor assembly is one of a plurality of sensor assemblies configured in a chain configuration and located within an optimized sheet metal casing. The optimized sheet metal casing may be connected to a computing device such as a server to measure temperature in the area proximate to the computing device. These measurements can be used by other processes to control and optimize temperature settings in the room where the computing device is located. [0037] The foregoing description of embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the present invention. The embodiments were chosen and described in order to explain the principles of the present invention and its practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

WHAT IS CLAIMED IS:

1. An apparatus for optimized sensor response time, the apparatus comprising: a first housing (110); a second housing (120), wherein the first housing and the second housing are coupled together to form an enclosure, at least one of the first housing and the second housing comprising at least one ventilation opening (130) therein to allow air to circulate through the at least one of the first housing and second housing; a printed circuit board (140) enclosed within the enclosure, wherein the printed circuit board is mounted on at least one elevated pedestal (250); and at least one environmental sensor (260) centrally mounted on the printed circuit board in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one environmental sensor includes at least one cut-out portion (170) of the printed circuit board.

2. The apparatus of claim 1 , further comprising a first interior wall (131) and a second interior wall (132), the first interior wall and the second interior wall being located on opposite ends of the at least one environmental sensor (260) and extending horizontally across one of the first housing and the second housing to isolate the environmental sensor from influences of other elements.

3. The apparatus of claim 1 , wherein heat producing components are not mounted between a first interior wall and a second interior wall.

4. The apparatus of claim 1 , wherein the at least one ventilation opening (130) comprise a porous covering to enable air to enter without the entrance of undesirable particles.

5. The apparatus of claim 1, wherein the environmental sensor measures one of temperature, humidity, or ambient air pressure.

6. The apparatus of claim 1 , wherein the printed circuit board includes a memory device (470).

7. The apparatus of claim 1, wherein the at least one cut-out portion of the printed circuit board comprises an area at least twice the area of the at least one environmental sensor footprint.

8. The apparatus of claim 1 , wherein the at least one ventilation opening comprises an area greater than the area of the at least one environmental sensor.

9. The apparatus of claim 1 , wherein the apparatus is one of a plurality of similar apparatuses coupled in a chain configuration and located within an optimized sheet metal casing.

10. The apparatus of claim 1 , wherein the printed circuit board comprises at least two cut-out portions on opposing sides of the at least one environmental sensor.

11. An system for optimized sensor response time, the system comprising: a computing device; a casing comprising a plurality of sensor assemblies interconnected via communication cables, wherein the casing is attached to the computing device; the sensor assembly comprising: a first housing (110); a second housing (120), wherein the first housing and the second housing are coupled together to form an enclosure, at least one of the first housing and the second housing comprising at least one ventilation opening (130) therein to allow air to circulate through the at least one of the first housing and second housing; a printed circuit board (140) enclosed within the enclosure, wherein the printed circuit board is mounted on at least one elevated pedestal (250); and at least one environmental sensor (260) centrally mounted on the printed circuit board in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one environmental sensor includes at least one cut-out portion (170) of the printed circuit board.

12. The system of claim 1 1 , further comprising a first interior wall (131) and a second interior wall (132), the first interior wall and the second interior wall being located on opposite ends of the at least one environmental sensor and extending horizontally across one of the first housing and the second housing to isolate the environmental sensor from influences of other elements.

13. The system of claim 1 1 , wherein heat producing components are not mounted on the printed circuit board in locations proximal to the environmental sensor.

14. The system of claim 1 1 , wherein the environmental sensor measures one of temperature, humidity, or ambient air pressure.

15. The system of claim 1 1 , wherein the printed circuit board includes a memory device (470).

16. The system of claim 1 1 , wherein the at least one cut-out portion of the printed circuit board comprises an area at least twice the area of the at least one environmental sensor footprint.

17. The system of claim 1 1 , wherein the at least one ventilation opening comprises an area greater than the area of the at least one environmental sensor.

18. The system of claim 1 1 , wherein the apparatus is one of a plurality of similar apparatuses coupled in a chain configuration and located within an optimized sheet metal casing.

19. The system of claim 1 1 , wherein the printed circuit board comprises at least two cut-out portions on opposing sides of the at least one environmental sensor.

20. An system for optimized sensor response time, the system comprising: a first housing means; a second housing means, wherein the first housing means and the second housing means are coupled together to form an enclosure, at least one of the first housing means and the second housing means comprising at least one ventilation means to allow air to circulate through the at least one of the first housing means and second housing means; means for mounting at least one sensing means, wherein the at least one sensing means is mounted centrally on the means for mounting in a position which is exposed to air circulating through the enclosure, wherein the periphery of the at least one sensing means includes at least one cut-out portion of the mounting means.