Patent Application
20070056947
1. Field of the Invention
The present invention relates generally to the use of electronics for measuring the presence of moisture, and particularly to the field of automation of the defrost mechanism in contemporary automobiles.
2. History of the Related Art
Vehicle drivers, particularly those who reside in the less temperate climates, are very familiar with the sight of frost, ice and snow on their windows during the winter months. While several advances over the years have made the defrosting process more amenable to drivers, most can still be found routinely scraping ice from their windows as the engine warms and the electrical systems charge. In some locations, such as the northern United States, the winters are cold enough to either necessitate a garage or require that the vehicle warm itself while the driver patiently awaits indoors.
Many vehicle manufactures, original equipment manufacturers (OEMs), and aftermarket services have introduced remote car starters into the market to somewhat streamline this winter ritual. In a typical remote starter system, the driver presses a button on a small transmitter that sends a signal, such as an RF signal, to a sensor in the vehicle that then automatically starts the engine. Thus, a driver can begin the defrost process from the comfort and warmth of his or her own home or office without having to venture into the cold. Although remote car starters are certainly an improvement, they are essentially passive in nature. Specifically, current remote starters cannot control the temperature within the vehicle, nor are they presently adapted to control any of the vehicle's electrical systems save for the engine starter itself. As such, while the engine is warming, the remaining vehicle systems may be inoperable or even working counter to the warming process, i.e. cooling down the interior of the vehicle.
In particular, people familiar with cold climates are also familiar with the effects of introducing a warm body into a vehicle's cold interior. The breath from the driver and any passengers will soon condense on the interior of the vehicle's windows, obscuring the visibility of all those present. Unfortunately, cold winters also correlate to hazardous driving conditions precipitated by the weather, and so any additional moisture on the windows will only amplify these problems. The typical solution to frost or fog on the interior of windows is to activate some kind of defrost mechanism, generally utilizing warm air from the engine or resistive heating from wires disposed within the glass.
While current defrost mechanisms are capable of improving driver visibility, it is also the case that many drivers find themselves on the highway with little or no visibility because the windows have not sufficiently warmed prior to driving. Thus, in order to improve driver visibility and automotive safety, there is a need in the art for an automated and controlled system for activating a vehicle's defrosting mechanism. There is also a need in the art for such a system that can be easily integrated into OEM articles as well as aftermarket equipment. Moreover, there is a need in the art for a sensor that automatically determines the presence and degree of moisture present on a surface, such as a vehicle window. Finally, there is a need in the art for an integrated system and sensor that can be automatically activated, for example by a remote car starter.
The present invention includes a system and a sensor usable for the automated activation of a defrosting mechanism; particularly the automated defrost of a vehicle window. The present invention includes a sensor that is adapted for the detection and measurement of changes in the dielectric constant of a dielectric disposed on a surface. More particularly, the sensor of the present invention is adapted for detecting changes in the phase of water, i.e. detecting if and when liquid water becomes frozen into frost, ice or snow. As described below more fully, owing to the relationship between the dielectric constant of various phases of water and capacitance, the sensor of the present invention utilizes fringing-field capacitors to determine the critical phase change.
The sensor is incorporated into a system for automatically activating a vehicle defrost, wherein the system includes a processor and various defrosting means for eliminating any solid water from a vehicle window. The processor is responsive to remote starting, which is defined herein as the starting of a vehicle engine from outside the vehicle, such as by RF transmitter. The processor is further adapted for controlling a vehicle HVAC system, engine and any other electronic heating means that may be utilized in heating and defrosting a vehicle window. It is customary for the windshield of a vehicle to be defrosted by heated air passing through the HVAC system while the rear window is defrosted by electrical means. Accordingly, the processor of the present invention is adapted for the control and regulation of each of these defrosting means alone or in combination with one another.
In operation, the sensor includes a fringe effect capacitor that is disposed on or near the surface to be defrosted. In preferred embodiments, the sensor is disposed between two panes of glass that form a window in the vehicle, such as the windshield. The capacitor of the sensor is particularly shaped and sized in order to optimally determine the dielectric constant of the water on the surface through changes in the capacitance. As discussed more fully below, changes in temperature correlate to the capacitor requiring more or less voltage to maintain a uniform potential difference, which in turn correlates to a change in the dielectric constant of the water on the surface. In particular, if any water on a vehicle window changes from liquid to solid form, its dielectric constant will also change causing a dramatic effect on the capacitance of the sensor of the present invention. In such cases, the processor is adapted to respond to signals indicative of a change in phase and automatically activate the vehicle defrosting means.
In summary, the present invention provides a novel and innovative sensor and system that can be readily incorporated into new and aftermarket vehicle systems. Those drivers in less temperate climates will also appreciate that the present invention is adapted for use in a remote starting system, thus permitting a user to defrost the windows of his or her vehicle without having to sit idly in the cold. These and various other features and benefits of the present invention are discussed more fully below with reference to the following drawings.
The present invention includes a system and sensor for the remote activation of a defrosting mechanism in a motor vehicle, such as, for example heated air or electronic heating. In particular, the present invention includes a sensor that is adapted to detect the temperature of moisture impending on a surface, such a quantity of frost, ice or snow settling on a windshield or rear window. By integrating the sensor of the present invention to a comprehensive automatic defrost activation system, the present invention improves upon the state of the art in numerous fashions as described in detail below.
The system 10 further includes a receiver 14 that is configured for receiving a remote signal and converting that signal into an electronic signal to be communicated to a processor 22. The receiver 14 is preferably configured for the receipt of incoming radiation, such as infrared or radiofrequency signals emitted by a handheld transmitter (not shown). In preferred embodiments, the receiver 14 is an RF receiver as typically used in the art of remote car starters.
The processor 22 is a central component of the system 10, and it includes the necessary hardware and operational software to perform the tasks set forth below. Those skilled in the art of electronics, particularly as it relates to automotive control units, will readily appreciate the functional requirements of the processor 22. The processor 22 is coupled to an engine 16 and heating, venting and air conditioning (HVAC) system 18. The engine 16 and HVAC system 18 are connected to each other in a manner familiar to those skilled in the automotive arts, such that heat generated by the engine 16 is utilized by the HVAC system 18 for heating, ventilating or cooling the interior of the vehicle.
The processor 22 is further coupled to an electronic heater 20 which functions to heat various surfaces of the vehicle through resistive heating, i.e. passing electrical current through resistive wires, such as the case in rear window defrost mechanisms. Although the electronic heater 20 is schematically depicted in
The processor 22 and the sensor 30 are coupled by a signal carrier 24 that is in direct electrical communication with the sensor 30, as discussed further below. The signal carrier 24 is responsible for providing electrical current to the sensor 30 during its operation as well as transmitting data generated by the sensor 30 back to the processor 22. Accordingly, the signal carrier 24 depicted herein is adapted for performing numerous functions, all of which can be readily engineered by those skilled in the art.
In operation, a user handling a remote control 32 activates the system 10 of the present invention by pressing a button or otherwise generating a signal in the direction of the vehicle 100. As noted above, the remote control 32 and receiver 14 are preferably of the RF type, although other systems of remote communication are contemplated herein as well. The receiver 14 is preferably disposed in a location that minimizes the signal interference from outside objects. As shown in
The sensor 30 operates on the principles governing the interaction between electric fields and dielectric materials. In particular, the sensor 30 is adapted for creating and maintaining a spatially variable but temporally constant electric field between two opposing poles. Based on the known reaction between capacitance and electric fields, the processor 22 can establish a normal or base capacitance measured by the sensor 30.
A known feature of so-called parallel plate capacitors, of which the sensor 30 of the present invention is a variation, is the fringe field effect. That is, although the electric field between parallel plate capacitors is generally uniform, at the edge of the parallel plates the field becomes non-uniform. This fringing field is responsible for the action on a dielectric that moves the dielectric into the uniform, parallel field portion of the capacitor. As a dielectric moves within a fringe-field capacitor, the battery must do some work in order to maintain the capacitor's potential. This amount of work is proportional to the dielectric constant of the dielectric, and thus a fringe-field capacitor can indirectly measure the dielectric constant of a dielectric by measuring the required potential change to maintain the capacitance.
It is also known that the thickness of the dielectric must be related to the thickness of the electrodes as well as the gap between the electrodes. Smaller electrodes with lesser gaps are preferred for measuring the dielectric constant of a relatively thin dielectric. Similarly, larger electrodes with greater gaps are preferred for measuring the dielectric constant of a relatively thick dielectric. The present invention provides for differing shapes and sizes of the electrode configurations, as the present invention is designed to confirm the presence of moisture on a surface, which may include thin layers of frost as well as thicker layers of ice and snow. The specific physical and electrical properties of the present invention are discussed below.
This aspect of the present invention is also shown in
The first conductor 302 and the second conductor 304 are arranged in a fringing field configuration, as discussed above. In particular, each of the first conductor 302 and the second conductor 304 includes a plurality of fingers that are interlaced as shown. Each of the fingers is variable in width and defines plurality of gaps 306 between the first conductor 302 and the second conductor 304. As shown in
In the embodiment shown in
Although various embodiments of the sensor 30 of the present invention have been presented, it should be understood that the relative geometries of the conductors and the gaps shown above are largely a matter of design choice, production costs and type of performance sought. While a preferred sensor 30 according to the present invention employs an interlaced structure as shown in
Similarly, although the system and sensor of the present invention have been particularly described with reference to preferred embodiments, it is understood that simple modifications of the present invention can be readily devised by those skilled in the art without departing from the spirit and scope of the present invention set forth in the following claims.
