1. A test answer form comprising:
a substrate having top and bottom surfaces;
chromogenic material applied to at least a top surface portion of said substrate, said chromogenic material being adapted to irreversibly generate a visible change in color in a selected area, upon exposure of the area to an activating agent;
a plurality of answer spaces printed on said chromogenic material, said plurality of answers spaces being arranged in X rows and Y columns, with each row being associated with a particular question, and each column with a possible answer choice wherein said chromogenic material can be activated by the activating agent to provide desired indicia in selected areas; and
a removable opaque layer overlaying at least a surface portion of the chromogenic material at each location of said plurality of answer spaces on said substrate, said opaque layer being present during application of said activating agent to conceal the indicia generated in said chromogenic material associated with the corresponding answer spaces.
2. The test form of claim 1, wherein the chromogenic material is in the form of a layer or coating.
3. The test form of claim 1, further comprising indicia applied on said substrate.
4. The test form of claim 1, further comprising indicia applied on said chromogenic material.
5. The test form of claim 1, further comprising indicia applied on said removable opaque layer.
6. The test form of claim 1, wherein the activating agent is heat.
7. The test form of claim 1, wherein the substrate further comprises indicia printed on said removable opaque layer.
8. The test form of claim 1, wherein the activating agent is selected from the group consisting of heat, light, radiation, and radio frequency.
9. The test form of claim 1, further comprising a transparent, non-removable layer interposed between the chromogenic material and the removable opaque layer.
10. The test form of claim 1, wherein said removable opaque layer further comprises a member selected from the group consisting scratch-off materials, rub-off materials and peel-off materials.
11. The test form of claim 10, wherein the scratch-off material is a latex-based material.
12. The test form of claim 1, wherein the substrate is selected from the group consisting of paper, plastic, metal, and combinations thereof.
13. A method for making a test form capable of being irreversibly and selectively encoded with desired indicia, said method comprising the steps of:
applying a chromogenic material on a substrate, said chromogenic material being adapted to irreversibly generate a visible change in color to form desired indicia in a selected area, upon exposure of the area to an activating agent; and
applying a removable opaque layer over said selected area or areas of the substrate over the chromogenic material, whereby said opaque layer is present during application of said activating agent, to conceal said indicia generated in said chromogenic material until such time that the corresponding overlaying opaque layer is removed; and
exposing a selected area of said opaque layer overlying said chromogenic material to the activating agent to generate in the underlying said chromogenic material an image or indicia said exposing step including processing the form through apparatus selected from the group consisting of heat apparatus, light radiating apparatus, and radio frequency apparatus.
14. The method of claim 13 wherein the substrate comprises a plurality of answer spaces printed on said substrate, each associated with an answer choice of a corresponding test question; and the chromogenic material overlaying portions of the substrate printed with said plurality of answer spaces.
15. A system for secretly customizing a test form, comprising:
a substrate;
a chromogenic material applied to at least a surface portion of said substrate, said chromogenic material being adapted to irreversibly generate a visible change in color to generate a desired indicia in a selected area, upon exposure of the area to an activating agent;
a removable opaque layer overlaying said chromogenic material before application of said activating agent thereto, to conceal indicia later formed in said selected areas; and
a printing apparatus adapted for selectively applying the activating agent on select portions of the opaque layer covering said chromogenic material of the substrate to produce indicia thereon.
16. The system of claim 15, wherein the substrate includes a plurality of answer spaces printed on said chromogenic material, each associated with an answer choice of a corresponding test question to provide said test form as a test answer form, and said removable opaque layer overlaying the chromogenic material at each location of said plurality of answer spaces on said substrate.
17. The system of claim 16, further comprising a scoring apparatus for automatically scanning said answer spaces to score a completed test answer form based upon the number of answer spaces uncovered for each question on a weighted basis; and a plurality of sets of a limited number of said test answer forms being provided for any one test, whereby each set of forms differs from any other of said plurality of sets of test forms in the arrangement of the X rows and Y columns for like questions and respective answers.
18. The system of claim 17, further comprising means for calculating a score for each question requiring an answer, said calculating means being programmable for giving full credit for a correct choice where only one answer space has opaque material removed in a given row and that space represents a correct answer, and less than full credit for a row in which the opaque material has been removed from more than one answer space, inclusive of the correct answer space.
19. The system of claim 17, wherein said test answer form includes a heading for recording desired information.
20. The system of claim 17, wherein said scoring apparatus includes:
a card reader including:
a plurality of detector means for reading answer choices at each answer location in each row of a test answer form, and
providing answer choice signals indicative of answer choices made for a given question on a test answer form;
control means responsive to control signals for advancing said test answer form row-by-row past said detector means;
microprocessor means programmed for both providing said control signals to said control means, and for receiving said answer choice signals for calculating the score for each question and the total test score; and
output port means for outputting examination score data from said microprocessor.
21. The system of claim 20, wherein said scoring apparatus further includes memory means for storing the answers and the total score for a plurality of successively scored test answer forms.
22. The system of claim 20, wherein said microprocessor means is programmed to perform partial credit scoring.
23. The system of claim 15, wherein said removable opaque layer of said test answer form is erasable.
24. The system of claim 15, wherein the removable opaque layer is machine-readable.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A matrix display device comprising on a substrate an array of addressable pixels each having a display element and a display element control circuit for controlling the operation of the display element, wherein the display element control circuit includes a charge storage capacitor and an associated thin film photosensitive semiconductor device coupled to the storage capacitor for regulating charge stored on the storage capacitor in accordance with light falling on the photosensitive device, wherein the photosensitive device comprises a strip of semiconductor material having doped contact regions laterally spaced on the substrate and an intervening region, and wherein the storage capacitor comprises a conductive layer extending substantially transversely of the semiconductor strip over one contact region thereof with a layer of dielectric material being disposed is between the conductive layer and that contact region.
2. A matrix display device according to claim 1, characterised in that the photosensitive device comprises a gated photosensitive device having a gate extending over the intervening region of the semiconductor strip and separated therefrom by dielectric material.
3. A matrix display device according to claim 2, characterised in that the gate dielectric of the photosensitive device and the dielectric material of the storage capacitor comprise portions of a common layer.
4. A matrix display device according to claim 2 or claim 3, characterised in that the gated photosensitive device comprises a TFT structure having similarly doped contact regions and an intrinsic semiconductor region extending between the contact regions.
5. A matrix display device according to claim 2 or claim 3, characterised in that the gated photosensitive device comprises a lateral gated pin device having oppositely doped contact regions and an intrinsic semiconductor region extending between the contact regions.
6. A matrix display device according to any one of claims 2 to 5, characterised in that the conductive layer of the storage capacitor is provided at the side of the semiconductor strip of the photosensitive device opposite to the gate of the photosensitive device and covers at least a part of the semiconductor strip so as to shield that part from light at that side.
7. A matrix display device according to any one of claims 2 to 6, characterised in that the gate of the photosensitive device is arranged to be biased such that current flow in the intervening region is due to generated photocurrent.
8. A matrix display device according to anyone of the preceding claims, characterised in that the strip of semiconductor material and the conductive layer at its part overlying the one contact region each have substantially parallel sides and extend generally at right angles to one another.
9. A matrix display device according to any one of the preceding claims, characterised in that the display element comprises a current-driven light emitting element and in that the photosensitive device is arranged to be responsive to light emitted by the display element.
10. A matrix display device according to claim 9, characterised in that the display element control circuit includes a drive TFT for controlling current through the display element in a drive period based on a drive signal applied to the pixel and stored as a charge on the storage capacitor, which capacitor is coupled to the gate of the drive TFT, and in that the photosensitive device is operable to regulate the charge on the storage capacitor and thereby the operation of the drive TFT.
11. A matrix device according to claim 9 or claim 10, characterized in that comprises an electroluminescent display element.