Patent Application
20070236469
Reference will now be made to the drawings in which the various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled in the art to make and use the invention. It is to be understood that the following description is only exemplary of the principles of the present invention, and should not be viewed as narrowing the claims which follow.
The presently preferred embodiment of the invention is essentially a capacitance-sensitive touchpad that is capable of performing proximity sensing of a fluid or fluids. Accordingly, a more accurate description is to state that the invention utilizes a capacitance-sensitive proximity sensing device that is disposed in a position relative to the container so that the device is capable of determining at least one characteristic of a fluid or fluids disposed within the container.
It is noted that information from the touchpad sensor circuitry 36 can be transmitted to a computer or other receiving device via wired or wireless means, as known to those skilled in the art.
Because the proximity sensing device operates on well-established principles of mutual capacitance-sensitive touchpad technology, as described in patents issued and pending of CIRQUE® Corporation, it is observed that the container 30 must be comprised of a non-metallic material in order to not interfere with the capacitance-sensitive proximity sensing device if the sensor array 34 is sensing through a wall of the container. In other words, any material that would interfere with the operation of a capacitance sensitive touchpad cannot be used for the container 30, unless a non-interfering aperture is provided. However, a sensing aperture through which the sensor array 34 might operate can be comprised of a material that is different from the rest of the container 30.
The nature of the invention is such that the container 30 storing the at least one fluid 32 can have a curved surface for attachment of the sensor array 34. This is because the capacitance-sensitive proximity sensing technology of the sensor array 34 is capable of being disposed on a flexible substrate such as MYLAR™. The use of MYLAR™ for the substrate material enables the sensor array 34 to conform to slight surface contours that might be found in the shape of the container 30. For example, a generally cylindrical glass container such as a bottle provides an arcuate or curved surface that is suitable for the attachment of the sensor array 34. Likewise, a cylindrical underground storage tank for petrochemicals such as gasoline will also provide a suitable surface.
There are some useful observations that can be made regarding the container 30 through which the sensor array 34 can detect and/or examine a fluid 32 within. For example, the container 30 can have a variety of curved surfaces that can be used as a location for attachment of the sensor array 34. When sensing directly through the walls of a container 30, the materials used in the manufacture of the container are also many, and include glasses and plastics. This also means that while the sensor array 34 requires attachment to a non-metallic material in order to perform sensing of the at least one fluid 32 on the opposite side, the sensor array 34 could be disposed, for example, against a glass aperture that has been made part of a container wall, wherein the remainder of the container 30 can be constructed of metal or other materials that will otherwise interfere with the sensor array 34. However, it is also important that the thickness of the material through which the capacitance-sensitive proximity sensing device must operate should not be made so thick as to interfere with fluid detection and/or examination. The closer the sensor array 34 of the capacitance-sensitive proximity sensing device is disposed to the at least one fluid 32, the more accurate and perhaps the more detailed the information that can be obtained will be.
The nature of the capacitance-sensitive proximity sensing device that includes the sensor array 34 described above utilizes mutual capacitance technology to detect and derive information about the at least one fluid 32 in the container 30. Mutual capacitance sensor technology is described, for example, in U.S. Pat. No. 5,305,017 issued to CIRQUE® Corporation. However, the capacitance-sensitive proximity sensing device of the invention also utilizes hidden touch surface HTS™ technology as described in issued U.S. Pat. No. 6,680,731 B2. This technology enables proximity sensing. In other words, it is not necessary for the at least one fluid 32 to be in physical contact with the sensor array 34 of the capacitance-sensitive proximity sensing device. The at least one fluid 32 must only be sufficiently close so as to be within a range of detection and/or examination of the present invention. Thus, the sensor array 34 may be disposed on the outside of a container 30 as long as the container wall is of a thickness and material that enable proximity sensing.
The electrodes of the sensor array 34 of the present invention are preferably comprised of a conductive ink that is “printed” onto MYLAR™ sheets and is described in the '731 patent. This method of fabrication is very simple and inexpensive. However, more conventional fabrication techniques that are used to manufacture conventional touch-sensitive touchpads such as those found in computer input devices can also be used.
So far, the specification has described a sensor array 34 of a capacitance-sensitive proximity sensing device that functions when disposed along the outside of a container 30. Another aspect of the invention is to dispose the capacitance-sensitive proximity sensing device inside the container 30 itself. This process may be as simple as coupling the capacitance-sensitive proximity sensing device to an inside surface of the container 30, and providing a means for signals to travel from the sensor array 34 to the touchpad control circuitry 36.
If the fluid within the container 30 will not harm the sensor array 34, the sensor array may be disposed so as to enter the fluid 32. This is illustrated in
It is observed that given the fact that the invention utilizes electricity to function, it will most likely be necessary to cover and insulate all electrical circuitry and exposed elements and electrodes of the sensor array 34 the capacitance-sensitive proximity sensing device from the fluid 32 in the container 30. It may also be necessary to protect the sensor array 34 from the corrosive and otherwise deleterious effects of the fluid 32 in the container 30. Materials used to cover the all the elements of the capacitance-sensitive proximity sensing device are well known to those skilled in the art of insulating electronic components from fluids when working in wet and corrosive environments.
Having described the invention in general terms, it is useful to examine some experimental results that demonstrate the capabilities of the invention. In this example, three fluids were poured into a container. No attempt was made to adjust the amount of each fluid disposed therein. The fluids were generally not miscible, and were comprised of tap water, automobile engine oil, and alcohol. The container was open to air.
The three fluids and air have different densities. Accordingly, the fluids separated into vertically distinct layers in the container. The lowest fluid in the container was water, then oil, and finally alcohol.
The fluids 32 have different dielectric and electrical properties, thereby causing each fluid to affect the conductive elements of the sensor array 34 in different and detectable ways. In this experiment, a normal touchpad from CIRQUE® Corporation that is used in computer input applications, and manufactured with a MYLAR™ substrate, was lowered directly into the fluid 32 in the container 30. The sensor array 34 was held in a vertically parallel orientation with respect to the upright sidewalls of the container 30. The sensor array 34 was coupled to touchpad sensor circuitry 36 also from CIRQUE® Corporation. The output of the electronic circuitry was then shown on a computer display as shown in
The computer display is simply one means by which signal strength information can be recognized as indicating a difference in detectable characteristics of different fluids that were in proximity to the capacitance-sensitive proximity sensing device. The output that was shown on the computer display indicates signal strength. Signal strength 40 thus can also be used to detect the presence or absence of a fluid, as well as the composition of detected fluids.
The signal strength 40 is a function of the relative dielectric constants and other electrical properties of each fluid. The results indicated that water yielded the highest signal strength 42, followed by alcohol 46 and then oil 44. The surface air showed no substantial signal level as expected with the sensor array and touchpad sensor circuitry being used. It will most likely be necessary to test the sensing and examination capabilities of the present invention in order to understand fully what the present invention is capable of detecting.
The output also indicates the level or depth 50 of each fluid, relative to the sensor array 34. Thus, the invention indicates the boundary between each of the fluids as indicated by a zero-crossing 52 on the graph between the layers of each of the fluids. It is noted that depth in the x-axis is in arbitrary units, but in this case is approximately 0.5 mm. Likewise, the signal strength shown in the y-axis is also in arbitrary units. What was important is that the signal strengths of the various fluids can be compared in order to obtain the desired information.
It is noted that previous experiments have shown that electrically conductive fluids (e.g. salt water) produce a maximum signal level that is not dependent on the dielectric constant of the conducting fluid for those conductive elements on the sensor array that are disposed in the conducting fluid. However, the sensing method of the present invention can still be applied to determine the fluid levels because measurements between conductive elements that are not in the conducting fluid will appear as previously described.
It is envisioned that the invention can be applied to process management and control in a variety of industries, including oil pumping from wells, chemical processing and storage, and the storage of other materials which can be in solid, fluid or gaseous form. In other words, the present invention will also function with gases and solids, to varying degrees of success.
It is also envisioned that the present invention can be used to: 1) detect changes in electrical properties of surrounding media due to chemical reactions or changes in temperature, 2) detect the existence and magnitude of waves or other disturbances in each of the layers of fluid, 3) detect the addition or removal of any fluid by any means, 4) detect the degree of mixing and/or separation of different fluids, 5) detect differences in properties of the fluid in multiple locations within the container by use of multiple sensing elements or sensing elements whose geometry is designed for such purposes, and 6) detect the effects in two or three dimensions, depending upon the sensor's geometry and accompanying data processing capabilities.
Regarding separation of the sensor array from the fluid being detected and/or analyzed, separation of as much as 0.3 inches has been demonstrated. The present invention is probably capable of even greater separations. Successful detection may also depend upon the electrical properties such as the dielectric constant of the fluid being measured. Thus, the sensor array can be coated with a variety of non-conducting materials or be separated from the container by a variety of non-conducting materials. Furthermore, orientation and geometry of the sensor array with respect to the fluid being detected and/or analyzed can greatly influence functionality of the present invention.
Other aspects of the present invention that should be mentioned are the ability to respond rapidly to changes over time, the ability to make continuous measurements as opposed to discrete, one-time measurements, and the fact that direct contact between the sensor and the fluid, solid, or gas is not required.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention. The appended claims are intended to cover such modifications and arrangements.
The present invention incorporates by reference all of the subject matter of issued U.S. Pat. No. 6,680,731 B2.
