Waveforms on a liquid crystal display
AssigneeControl Interface Company Limited
InventorWilliam Bohmer
Life of this patent
Estimating the term…
Abstract
Liquid crystal display for use in an oscilloscope. Analog multiplexing techniques enable displaying of waveforms of input signals with frequencies as high as 1 MHz. An xy grid is formed by two interleaved arrays of alternate parallel transparent electrodes. Use of liquid crystal material results in very low power consumption and voltage threshold, improved lifetime, a wide viewing angle, and no image washout at high ambient light levels. Addition of a digital voltmeter, frequency counter, auto sync circuitry, dual trace, and movable cursor expands the capabilities of the display. A gray scale surrounds the actual null points on the display, allowing suitable resolution with a minimum of channels.
Claims57
Apparatus for providing a visual display of an electrical input signal, comprising:
- a viewing screen of predetermined thickness having two oppositely disposed parallel faces and formed of a material having optical properties which in any predetermined portion of the screen are variable in response to the application of a predetermined electrical potential across the thickness of the screen in the predetermined portion, the variable optical properties enabling the transmission of light to be controlled with respect to the predetermined portion,
- a plurality of first conductive elements disposed spaced apart with respect to one another, the plurality of first conductive elements being positioned adjacent and substantially parallel to one face of the screen,
- means for applying a voltage gradient across said plurality of first conductive elements to produce a different predetermined voltage on each of the plurality of the first conductive elements and wherein the relationship of each predetermined voltage with respect to another is predetermined,
- a plurality of second conductive elements disposed spaced apart with respect to one another, the plurality of second conductive elements being positioned adjacent and substantially parallel to the other face of the screen and extending at an angle to the plurality of first conductive elements, means for sampling said electrical input signal at predetermined sample times and for producing respective input voltages, each of which being a predetermined function thereof and independent of any other input voltage, and
- means responsive to said sampling means for sequentially coupling to each of the plurality of second conductive elements said respective input voltages, whereupon each input voltage which is coupled to a respective one of the plurality of second conductive elements coacts with the different predetermined voltage of each of the plurality of first conductive elements across the thickness of the screen to form a plurality of different control voltages impressed across the screen, each of said control voltages enabling the optical properties of the predetermined portion of the screen across which the control voltage is applied to control the transmission of light with respect to the predetermined portion when said control voltage corresponds to a predetermined electrical potential.
An oscilloscope for providing a visual display including a waveform or a bar chart of information contained in an input signal comprising:
- a viewing screen of predetermined thickness and formed of liquid crystal material which is adapted to experience a change in optical properties in a portion of the screen which is subjected to a predetermined electrical state extending across the thickness of the screen,
- a first substantially planar array of a plurality of first electrically conductive elongated elements extending spaced apart and parallel with respect to one another, the first array being disposed parallel and adjacent a surface of the screen,
- means for establishing a predetermined voltage gradient across said first array, with each of the first conductive elements being at a different predetermined electrical potential with respect to the other first electrically conductive elements,
- a second substantially planar array of a plurality of second electrically elongated conductive elements extending spaced apart and parallel with respect to one another, the second array being disposed substantially parallel and adjacent to the other surface of the screen, the plurality of second conductive elements in the second array extending at an angle to the plurality of first conductive elements in the first array,
- means for sampling said input signal at sample times and for producing respective input voltages, each of which being a predetermined function thereof and independent of any other input voltage, and
- means responsive to the sampling means for applying sequentially to each of the plurality of second conductive elements said respective input voltages, whereupon each input voltage which is coupled to a respective one of the plurality of second conductive elements coacts with the predetermined different voltage of each of the plurality of first conductive elements across the thickness of the screen to form a plurality of different control voltages impressed across the screen, each of said control voltages enabling the optical properties of the predetermined portion of the screen to which the control voltage is applied to control the transmission of light with respect to the predetermined portion when said control voltage corresonds to a predetermined electrical potential and thereby provide the visual display.
Method for providing a visual display of an electrical input signal or a viewing screen of predetermined thickness having two oppositely disposed parallel faces and formed of a material having optical properties which in any predetermined portion of the screen are variable in response to the application of a predetermined electrical potential across the thickness of the screen in the predetermined portion, the variable optical properties enabling the transmission of light to be controlled with respect to the predetermined portion, the viewing screen including a plurality of first conductive elements disposed spaced apart with respect to one another, the plurality of first conductive elements being positioned adjacent and substantially parallel to one face of the screen,
- the viewing screen further including a plurality of second conductive elements disposed spaced apart with respect to one another, the plurality of second conductive elements being positioned adjacent and substantially parallel to the other face of the screen and extending at an angle to the plurality of first conductive elements, the method comprising the steps of:
- applying a voltage gradient across said plurality of first conductive elements to produce a different predetermined voltage on each of the plurality of the first conductive elements and wherein the relationship of each predetermined voltage with respect to another is predetermined,
- sampling said electrical input signal at predetermined times for producing respective input voltages, each of which being a predetermined function thereof and independent of any other input voltage, and
- responsive to said sampling sequentially coupling to each of the plurality of second conductive elements said respective input voltages, whereupon each input voltage which is coupled to a respective one of the plurality of second conductive elements coacts with the different predetermined voltage of each of the plurality of first conductive elements across the thickness of the screen to form a plurality of different control voltages impressed across the screen, each of said control voltages enabling the optical properties of the predetermined portion of the screen across which the control voltage is applied to control the transmission of light with respect to the predetermined portion when said control voltage corresponds to a predetermined electrical potential.
Dependencies are inferred from the claim text.