APPARATUS FOR DISPLAY DURATION MODULATION
First Claim
1. A display system comprising in combination:
- a. a panel of selectively positioned light valves having Variable light transmitting characteristics;
b. a light source impinging upon one surface of said light valve panel;
c. a video signal source;
d. an address scanner responsive to said video signal source for scanning said light valve panel along its X and Y axis and for intensity modulating said light valve panel along its Z axis;
e. a plurality of storage members respectively connected in parallel to said light valves;
f. a plurality of first circuit means respectively connected between said address scanner and said storage members for selectively charging said storage members during a first preselected time period; and
g. a plurality of second circuit means respectively connected in parallel to said storage members for effectively maintaining the charge on said storage members during a second preselected time period;
wherein h. said address scanner selectively connects each of said first an second circuit means to its respective storage member respectively during said first and second preselected time periods;
whereby i. during said first preselected time period each of said storage members selectively pass light to the other side of said panel; and
whereby j. during said second preselected time period of said storage members are selectively maintained in their light passing condition.
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Abstract
The display state of a light element may be modulated by a video signal in a system that includes a storage device for transforming the video signal, which is available only during a writing time of short duration, to a display signal. A writing circuit for the light element includes the storage device and provides a writing equivalent circuit having a time constant short in comparison to the length of the writing time. A holding circuit also includes the storage device in an equivalent circuit that has a time constant long in comparison to one frame time. One frame time equals the time spacing between subsequent addressing of one light element in a display consisting of a plurality of such light elements. Inasmuch as the brightness of a light element is measured by the light integral of the element over one frame time, a halftone display can be effected if the display duration of each element in an array of such elements is video modulated by means of the writing circuit and the holding circuit.
91 Citations
8 Claims
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1. A display system comprising in combination:
- a. a panel of selectively positioned light valves having Variable light transmitting characteristics;
b. a light source impinging upon one surface of said light valve panel;
c. a video signal source;
d. an address scanner responsive to said video signal source for scanning said light valve panel along its X and Y axis and for intensity modulating said light valve panel along its Z axis;
e. a plurality of storage members respectively connected in parallel to said light valves;
f. a plurality of first circuit means respectively connected between said address scanner and said storage members for selectively charging said storage members during a first preselected time period; and
g. a plurality of second circuit means respectively connected in parallel to said storage members for effectively maintaining the charge on said storage members during a second preselected time period;
wherein h. said address scanner selectively connects each of said first an second circuit means to its respective storage member respectively during said first and second preselected time periods;
whereby i. during said first preselected time period each of said storage members selectively pass light to the other side of said panel; and
whereby j. during said second preselected time period of said storage members are selectively maintained in their light passing condition.
- a. a panel of selectively positioned light valves having Variable light transmitting characteristics;
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2. The display system of claim 1 wherein each of said valves have a light blocking and light passing state, and wherein each of said light valves are in their passing state when their respective storage member is charged above a threshold valve and in their light blocking state when their respective storage member is discharged below threshold valve.
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3. The display system of claim 1 wherein each of said storage members in combination with their respective first circuit means has a time constant that is relatively short with respect to said first preselected time period.
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4. The display system of claim 1 wherein each of said storage members in combination with their respective second circuit means has a time constant relatively large with respect to the time required for said address scanner to scan said light valve panel.
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5. The display system of claim 2 and further including means for biasing said video signals slightly lower than the threshold level required to change said light valves from their light block state to their light passing state.
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6. The display system of claim 1 wherein each of said storage members includes a capacitor that is selectively connected in series with a first resistor during said first preselected time period, and selectively connected in parallel to respective second resistors during said second preselected time period.
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7. The display system of claim 1 wherein:
- a. said light valves are selectively connected in rows and columns to form said panel; and
wherein b. said address scanner scans said light valves by row and column and selectively couples said video signal to said storage members for selectively changing their light transmitting characteristics.
- a. said light valves are selectively connected in rows and columns to form said panel; and
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8. Apparatus for selectively varying the display state of a matrix of light elements of the type having light transmitting and light restraining states comprising in combination:
- a. a video signal source;
b. scanning means responsive to said video signal for selectively scanning said light elements of said matrix by row and column;
c. a plurality of storage means respectively connected in parallel to said light elements;
d. charging means selectively connected in series with a respective one of said storage means in response to said scanning means during a first preselected time period for selectively changing its respective light element from one of its states to its other state; and
e. a plurality of holding and discharging means effectively connected in parallel with a respective one of said storage means in response to said scanning means during a second preselected time period for holding its respective lIght element in its selected state during said second preselected time period;
f. during said first preselected period said light elements selectively transmit or restrain light from one side of said matrix to the other; and
whereby. g. each of said light elements are maintained in their second light transmitting state for a time period larger than the time period required for said scanning means to scan said matrix by row and column.
- a. a video signal source;
Specification