Data processing: measuring – calibrating – or testing – Measurement system – Measured signal processing
Reexamination Certificate
1997-11-04
2001-03-13
Wachsman, Hal (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Measured signal processing
C702S127000, C702S057000, C345S030000, C345S033000, C345S035000, C345S036000
Reexamination Certificate
active
06202039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the display of measured parameters generally and, more particularly, but not by way of limitation, to novel compact, low-cost, semiconductor device and methods for receiving arbitrary input parameters and driving selected display devices and methods therefor, which are particularly useful in motorized vehicles.
2. Background Art
Particularly in motorized vehicles, but not necessarily limited thereto, there is need for measuring and displaying physical parameters such as pressure, temperature, liquid level, voltage, and current and, in some cases, providing high and/or low indications thereof. Conventionally, almost all of these functions are satisfied by various electromechanical gauges which are relatively expensive and space-consuming. When high and/or low indication is required, auxiliary sensors and displays are frequently employed, as it is more economical to do so rather than derive the presence of an extreme condition from the normal measurement signal. Also, in order to accommodate the electromechanical display devices, the sensors must often be designed to be very non-linear, since the amount of freedom to shape the display device is quite limited. This latter factor introduces additional cost and space consumption to conventional systems.
It would be desirable to have a method and apparatus for physical parameter measurement and display which is particularly well suited for parameters such as pressure, temperature, liquid level, voltage, and current. There exists a wealth of inexpensive sensors and transducers which can provide electrical inputs to such a device. Unfortunately these transducers and sensors come in a very large number of electrical forms and non-linearities. It is, therefore, a first objective of the present invention to accept an arbitrary shape and, to some extent, arbitrary amplitude input signal.
It is very often desirable to contour the displayed information in order to shape, compress, or expand the parameter for ergonomic or resolution reasons. It is, therefore, a second objective of the invention to display the parameter in an arbitrary shape.
Many of the available inexpensive transducers and sensors have rather low impedances, requiring an excessive amount of power (in the context of the “micro-instrument” provided by the present invention). It is, therefore, a third objective of the invention to operate the mating transducer in one of several power conserving modes.
Some transducers are designed to provide an increasing output for an increasing physical parameter while others produce a decreasing output for an increasing input. It is, therefore, a fourth objective of the invention to treat the input in a normal (ascending) mode or an inverted (descending) mode.
In some cases the input signal comes from a calibrated source (e.g., absolute volts), but in other cases the input signal comes from a transducer which must be excited by the device (frequently in a power conserving mode). It is, therefore, a fifth objective of the invention to operate in either an “absolute” or “ratio” mode.
Some parameters are inherently jittery, or noisy (such as a fuel sender in a sloshing tank). It is, therefore, a sixth objective of the invention to provide varying degrees of damping or slew rate control. For example, relatively fast for pressure and voltage, or relatively slow for fuel level and temperature.
In critical applications, a second sensor is frequently introduced, as noted above, to warn or shut down an operation when an out-of-specification condition is detected. It is a seventh objective of the invention to provide a programmable over and/or under warning output.
In other critical applications, both a second and third sensor may be introduced to warn and/or shut down an operation when either a low or high out-of-specification condition is detected. It is, therefore, an eighth objective of this device to provide at least one additional programmable over and/or under warning output.
Most instruments designed for the vehicle market incorporate illumination. It is, therefore, a ninth objective of the invention to provide self-illumination by directly driving light-emitting diodes.
The light emitting diodes may be illuminated sequentially (pointer mode) or additively (bar graph mode). It is, therefore, a tenth objective of the invention to provide self-illumination in either of two modes, pointer or bar graph.
In some applications, such as portable battery operated equipment, it becomes necessary to run the device and transducer at very low power levels. It is anticipated that an inherently low power (or high impedance) transducer will be operated in one of the power conserving modes, and that the device will be operated in a direct drive LCD mode. In this mode a liquid crystal display may be driven without the need for temperature compensation over the temperature range of −40 degree C. to +85 degree C. It is, therefore, an eleventh objective of the invention to directly drive a liquid crystal display.
The LCD may be activated sequentially (pointer mode) or additively (bar graph mode). It is, therefore, a twelfth objective of the invention to provide low power LCD activation in either of two modes, pointer or bar graph.
Both the LED and LCD Display drives address individual segments. These segments may be arranged in limitless configurations; straight line vertical, straight line horizontal, straight line diagonal, curved up, curved down, patterns, matrices, etc. Two or more light emitting diodes can be simultaneously energized in series. Two or more LCD segments can be simultaneously energized in parallel. Static light emitting diodes can be energized directly, but static LCD segments require an AC drive signal. The static elements are envisaged as part of the scale legend or information, and are intended to be active whenever the power is applied. It is, therefore, a thirteenth objective of the invention to provide a continuously operating LCD segment driver.
The light emitting diodes can be assembled in specific color coded formats. For example, the traditional OK-Caution-Warning/Stop sequence of Green-Yellow-Red can be arranged within the display to impart that interpretation, while simultaneously “pointing” to the measured value. When coupled with scale expansion and contraction contouring the display can impart an unusually large amount of accurate information with relatively few display elements. It is, therefore, a fourteenth objective of the invention to provide color coded status information integral with the measurement.
When an out-of-specification condition is detected, it is often desirable to “flash” the display to draw attention to the fact that a problem exists. It is, therefore, a fifteenth objective of the invention to provide various flashing modes at the upper limits of the range or the lower limits of the range.
If an out-of-specification condition can occur at both extremes of the range, it may be desirable to “flash” the display for both conditions. It is, therefore, a sixteenth objective of the invention to provide various independent flashing modes at both the upper limits of the range and the lower limits of the range.
When information is known to vary at a slow rate, it may be desirable to limit the update of the display to rather long intervals to reduce apparent “flicker” when a borderline reading is made in a noisy environment. It is, therefore, a seventeenth objective of the invention to provide various conversion rate intervals. This will usually be used in conjunction with the slew rate control (objective six).
When information is known to be somewhat noisy, it may be desirable to introduce hysteresis to lessen the likelihood of borderline flicker. It is, therefore, an eighteenth objective of the invention to provide an hysteresis on/off feature. This will usually be used in conjunction with the conversion rate control (objective seventeen) and the slew rate control (objective six).
Having separate control over slew rate,
Crozier John H.
Curtis Instruments, Inc.
Wachsman Hal
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