Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-09-24
2001-03-06
Chow, Dennis-Doon (Department: 2775)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S034000, C345S038000, C349S035000
Reexamination Certificate
active
06198466
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to indicators and/or display units and more particularly to electronic MFDI (multifunctional digital indicators) or displays such as event counters or elapsed time indicators and the like which can preserve the status of the time or event display even in the event of a complete power loss for an indefinite period of time.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
There are numerous situations where the amount of time or elapsed time a machine or process runs may be of critical importance. The running time of a jet engine is one specific example. Likewise, there are numerous situations where the number of occurrences of a particular event or activity may also be important if not critical. However, the events may occur over a long period of time such as months or even years with complete unpredictability. Similarly, the running of the machine or process may start and stop at unpredictable times over lengthy periods. Consequently, it is important to be able to record the occurrence and/or amount of such unpredictable events and/or running time automatically and without having to maintain one or more individuals at the necessary locations to monitor and manually record such occurrences and running times.
In the past, events or elapsed time indicators which operated automatically without a human attendant, and which could maintain their status even in the event of complete loss of electrical power were typically mechanical clock-like devices or hybrid devices which included a significant amount of precision machining and provided mechanical-type displays which were electrically driven and electronically controlled. Excellent examples of such prior art devices are manufactured by Electrodynamics, Inc. in Rolling Meadows, Ill., the assignee of the present invention under the product name Dynatime®. Although such mechanical or hybrid devices provide excellent performance and dependability, such devices include a significant amount of precision clock-like machining which is expensive to produce and may be susceptible to damage by harsh environment and handling conditions.
Unfortunately, such devices having such a high content of precision manufacturing typically require substantially different designs for counting events and/or recording elapsed time. Further, such mechanical devices may also have high electrical power requirements.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an efficient and dependable elapsed time or event counter which is both inexpensive to manufacture and to maintain.
It is a further object of the present invention to provide a single basic designed device which can be easily programmed for any one of several specific purposes and to operate from substantially any available power source.
It is yet another object of the present invention to provide a device which has form, fit, and function requirements such that the device can readily be substituted for existing mechanical and/or hybrid devices which perform the same functions.
These and other objects are achieved by the apparatus and methods of this invention for a multifunctional digital indicator which comprises an array of ChLCD (Cholesteric Liquid Crystal Display) elements such as is available from Advanced Display Systems of Amarillo, Tex. arranged in a plurality of rows and a plurality of columns. The array of ChLCD elements requires a first voltage of an absolute value to switch to a transparent state and a second voltage of an absolute value to switch to a reflective state. These voltages will hereinafter be referred to as V
TRANS
to indicate the voltage required to switch to the transparent state and V
BRIGHT
to indicate the voltage required to switch to the reflective state. The voltage V
BRIGHT
will typically be higher than the voltage V
TRANS
. The display device will also include a power source providing a source of power having a voltage V
IN
. According to one embodiment of the present invention, the input voltage V
IN
may be a DC voltage which has a voltage level varying between 14 to 35 volts DC with a nominal value of 28 volts DC. In addition, according to the present embodiment, the device can also accept an AC voltage between 15 to 138 volts AC RMS with a nominal voltage of either 26 volts or 115 volts and a frequency of 60 cycles per second or 400 cycles per second.
A controller or microcontroller receives the input data or information and provides the control signal for controlling the device of the invention. Also included in the device circuitry is a voltage multiplier circuit which receives the voltage input V
IN
and provides at least three output voltages such as V
MAX
, V
MAX
/3, and 2V
MAX
/3. The requirement to provide three voltages at these ratios will be discussed hereinafter, but briefly these voltages assure that the ChLCD elements change between the transparent and reflective state upon demand, but will not inadvertently change state during other voltage transitions.
The circuitry also includes a row driver which receives at least one of the output voltages from the voltage multiplier such as the 2V
MAX
/3 voltage. The row driver also can provide zero volts to the rows in the ChLCD array. Thus, according to one embodiment, the row driver will provide either zero volts or 2V
MAX
/3 volts to a selected one of the rows of the ChLCD elements in response to a control signal from the controller.
Also according to a preferred embodiment, there is provided a column drive circuit for each of the columns in the ChLCD array. Each of these drive circuits receives at least the V
MAX
voltage and the V
MAX
/3 voltage from the voltage multiplier and selectively applies one of these voltages to each of the plurality of columns of the array in response to a control signal from the controller.
Because of peculiar operating characteristics of the ChLCD elements, the method of applying and removing specific voltages which are developed across the individual elements of the ChLCD array must follow a precise sequence. As will become clear hereinafter, it may be possible to have several sequences of events for the application of power which will properly operate the ChLCD elements. However, it is necessary that once one of the sequences has been decided upon and programmed into the controller of the device, this sequence must be followed if the device is to properly function and inadvertent changes of state are to be avoided.
Thus, according to one embodiment where the elements are “on” when in the “transparent” or V
TRANS
state and “off” when in the “reflective” or V
BRIGHT
state, the following sequence of steps is followed. All of the plurality of rows are set to zero and the voltage for all of the plurality of columns is set to the voltage V
MAX
, where V
MAX
=V
BRIGHT
. Thus, the maximum voltage V
BRIGHT
will be across each of the elements such that the array is now erased and there are no elements in the “on” condition. A voltage V
HOLD
is then applied to the plurality of columns and in the present embodiment the voltage V
HOLD
=V
MAX
/3, where V
MAX
=V
TRANS
. Another voltage referred to as a “first” voltage is then applied to each of the rows of the plurality which includes at least one element of the multiplicity of elements which is selected to be in the “on” condition. According to the preferred embodiment being described, this first voltage is equal to “zero” volts. In a similar manner, a second voltage is applied to each of the remaining rows of the plurality of rows and according to the preferred embodiment this second voltage equals 2V
MAX
/3. A column voltage V
ON
is then provided for the necessary period of time to cause the change of state of the ChLCD elements to the “on” condition and in the preferred embodiment, the voltage V
ON
=V
TRANS
. The steps of applying the column voltage V
HOLD
through the step of applying the column voltage V
ON
are then repeated for each colu
Morich Robert S.
Szeplaki Victor J.
Awad Amr
Chow Dennis-Doon
Jones Day Reavis & Pogue
L-3 Communications, Electrodynamics, Inc.
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