Liquid crystal cells – elements and systems – Liquid crystal system – Heads-up display
Reexamination Certificate
2001-03-23
2003-11-25
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal system
Heads-up display
C359S630000, C345S007000
Reexamination Certificate
active
06654070
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to liquid crystal displays and, more particularly, to a liquid crystal display and touch screen technology for a windshield of an automotive vehicle.
2. Description of the Related Art
1) Liquid-Crystal
The technology of liquid-crystal is well known and extensively utilized. Calculators primarily use liquid-crystal for their numeric displays. These are known as liquid-crystal-displays (LCD). These LCD's are produced in a variety of shapes.
Since liquid crystal molecules respond to an external applied voltage, liquid crystal can be used as an optical switch, or light valve. A common arrangement is two parallel glass plates, each with a polarizing film on its outer side. The space between the plates is filled with the liquid crystal polymer. The technical designation for the most commonly used liquid crystal type is twisted nematic (TN), and the twist refers to the tendency of the polymers to form chains that rotate from one side of the gap between the plates to the other side. This alignment can be changed with an external electric field, allowing the polarization of incoming light to be changed.
Light passing through one of the polarizers, then through the cell (the arrangement of plates, and liquid crystal), has its polarization direction rotated, following the physical rotation of the liquid crystal. When viewed, the cell is clear, or transmitting. A transparent electrical conductor is deposited on the inner surfaces of the glass plates, and patterned into a series of mutually perpendicular lines. If a voltage is placed across the cell gap by addressing the appropriate line on each side of the cell, the liquid crystal reorients to follow the applied electric filed, and the material is “untwisted”. As long as the voltage is present, the passage of light will be blocked by the exit polarizer. When the voltage is turned off, the liquid crystal returns to its original state, and the pixel (defined viewing area) becomes clear again. Typical voltages and currents are quite low, which is why liquid crystal displays have been incorporated in battery-operated equipment, and in other applications where power consumption is an issue.
2) Heads-Up-Display (HUD)
Originally developed for the use of the military in fighter aircraft. Now HUD has been translated to broader commercial use in automotive vehicles.
A HUD works by reflecting an image off the windshield into the drivers line of sight. The image presented to the driver is information pertaining to the vehicle's status such as speed. This allows the driver to easily determine the vehicle speed while looking out through the windshield. Thus allowing the driver to maintain their heads up position while driving instead of breaking their view of the road to determine speed. A light intensive image is necessary so that it is able to reflect off the windshield. The equipment necessary to generate the image is set below the windshield and the image generated is projected up into the windshield which in turn is reflected off the windshield and into the drivers line of vision. Sometimes special optics are used to define and focus the image so that after the image is reflected off the windshield the driver is presented with a clear and coherent image.
3) Touch Screen Technology
Touch screen technology is in use on many video screens to enhance user interface. The user can activate software selection simply by touching the display screen. One technical way of detecting if the display screen has been touched has been described in U.S. Pat. No. 3,636,409 by Norman J. Braaten. Transparent electrodes are placed on the surface of the screen. When a person touches one of the transparent electrodes, an increase in capacitance occurs which is sensed by the change in frequency of an oscillator circuit. The oscillations corresponding to the various electrodes are counted and compared to a threshold value to provide an indication of which, if any, of the electrodes has been touched. The software then uses this as input information and resumes with its program.
4) Dashboard Layout and Configuration
Due to the numerous amount of features currently available and with even more desired by designers the available dashboard real-estate is extremely limited. Also the available space is further constrained because some features are essential and required such as airbags. Among the features are things like; engine performance indices (engine temperature, oil pressure, electrical voltages, etc . . . ), air vents, vehicle speed, time, navigation aids, radios, CD players, cassette players, climate controls, cell phones, cup holders, etc . . . . All of these features are competing for very limited dashboard real-estate.
SUMMARY OF INVENTION
According to the present invention, an interactive heads up display (IHUD) is a passive information display and allowing selection that uses the windshield as the actual platform. Passive in the sense that the display isn't generating the light, it simply locks ambient light. Activation of information on the IHUD is accomplished using the windshield as well. The interactive heads up display is the integration of the windshield, an LCD, and a selection device. So that the windshield acts as a multifunction device, as a device to shield the driver from wind, as a display platform and as a device to control the displayed information.
The interactive heads up display includes the following elements, two sheets of glass, a layer of liquid crystal, an annular shaped piece of plastic, three sets of transparent electrodes, two polarizing elements, and equipment to provide a voltage to the interactive heads up display assembly and to measure electrical characteristics.
The two sheets are congruent pieces of glass that when sandwiched together form the windshield. Sandwiched between these two sheets of glass is a very thin layer of liquid crystal. In addition, also sandwiched in between is a clear ring of plastic surrounding the liquid crystal to prevent the liquid crystal from moving so that its position remains static. Two sets of transparent electrodes are positioned at the inner surfaces of both sheets of glass so that electrodes are in direct contact on both sides of the liquid crystal. On the outside sheets of glass two polarizers, crossed with each other, are placed on both sides of the windshield over the region of the liquid crystal, so that any light passing through the liquid crystal will also first pass through one polarizer, the liquid crystal, and then the other polarizer. The windshield can now act as a LCD, except in a see-through mode. Whenever an electric field is applied to the liquid crystal via the transparent electrodes, this causes the region to appear dark. This by the principals of LCD. By arranging the electrodes in an ordered manner, any information can be displayed, such as can be noted by LCD presently found today. The third set of electrodes are attached to the surface of the windshield. This surface being on the interior of the vehicle and accessible to a vehicle driver/occupant. The vehicle driver/occupant can now easily touch these transparent electrodes and change the measured electrical characteristics of these electrodes. This change then be used to switch on or off the displayed information.
The interactive heads up display functions using the similar principals found on touch screen displays and on LCD calculators. Except the glass of the windshield acts as the implementation platform. First the glass acts as selection platform. And also the windshield acts as viewing platform as the case of a calculator. But the glass is not functioning exactly the same because the driver is presented the information by ambient light passing through the windshield.
The purposes of the present invention are as follows:
1. Currently because the space found on dashboards is limited and very valuable in terms of competing interests. The interactive heads up display would provide additional area for information displa
Bliss McGlynn P.C.
Parker Kenneth
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