Semiconductor memory device
First Claim
Patent Images
1. A semiconductor memory device comprising:
- a pair of bit lines;
a word line;
a cell plate electrode;
a memory cell for storing normal data, connected to said bit lines, said word line, and said cell plate electrode; and
a prevention means for preventing readout of said normal data stored in said memory cell by destroying said normal data, after a number of readouts already executed on said normal data reaches a predetermined limiting number of readouts.
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Abstract
A semiconductor memory device comprising a pair of bit lines, a word line, a cell plate electrode, a memory cell connected to each of the bit lines, the word line and the cell plate electrode, and a prevention means that permits only a predetermined number of readouts of data stored in the memory cell, after which the data is destroyed and is not retrieved with subsequent readout attempts.
31 Citations
28 Claims
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1. A semiconductor memory device comprising:
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a pair of bit lines; a word line; a cell plate electrode; a memory cell for storing normal data, connected to said bit lines, said word line, and said cell plate electrode; and a prevention means for preventing readout of said normal data stored in said memory cell by destroying said normal data, after a number of readouts already executed on said normal data reaches a predetermined limiting number of readouts. - View Dependent Claims (2)
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3. A semiconductor memory device comprising:
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a pair of bit lines; a word line; a cell plate electrode; a memory cell for storing data, connected to said bit lines, said word line, and said cell plate electrode; and a prevention means for preventing normal readout of said data store in said memory cell, after a number of readouts already executed on said data reaches a predetermined limiting number of readouts, wherein said preventing means comprises an alteration means for altering bit line capacitance of at least one of said bit lines. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A semiconductor memory device comprising:
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a pair of bit lines; a word line; a cell plate electrode; a memory cell for storing data, connected to said bit lines, said word line, and said cell plate electrode; and a prevention means for preventing normal readout of said data stored in said memory cell, after a number of readouts already executed on said data reaches a predetermined limiting number of readouts, wherein said prevention means comprises a signal reversing means for altering a normal reversing timing for a rewriting operation of at least one logical voltage supplied to said memory cell for a rewriting operation conducted after said predetermined limiting number of readouts have been executed. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A semiconductor memory device comprising:
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a pair of bit lines; a word line; a cell plate electrode; a memory cell for storing data, connected to said bit lines, said word line, and said cell plate electrode; and a prevention meads for preventing normal readout of said data stored in said memory cell, after a number of readouts already executed on said data reaches a predetermined limiting number of readouts, wherein said prevention means is a stopping means for stopping supply of a control signal to said memory cell after said predetermined limiting number of readouts have been executed on said stored data. - View Dependent Claims (18, 19, 20, 21)
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22. A method of limiting a number of readouts of normal data stored in a semiconductor memory device comprised of a pair of bit lines, a word line, a cell plate electrode, a memory cell connected to said bit lines, said word line, and said cell plate electrode, wherein said limiting method comprises the steps of:
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determining a number of readouts already executed on said normal data; determining whether said number of readouts already executed on said normal data has reached a predetermined limiting number of readouts; preventing subsequent readouts of said normal data by destroying said normal data upon determination that said number of readouts already executed on said normal data has reached said predetermined limiting number of readouts. - View Dependent Claims (23, 24)
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25. A method of limiting a number or readouts of data stored in a semiconductor memory device comprised of a pair of bit lines, a word line, a cell plate electrode, a memory cell connected to said bit lines, said word line, and said cell plate electrode, wherein said limiting method comprises the steps of:
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determine a number of readouts already executed on said stored data; determining whether said number of readouts already executed on said stored data has reached a predetermined limiting number of readouts; preventing subsequent readouts of said stored data upon determination that said number of readouts already executed on said stored data has reached said predetermined limiting number of readouts, wherein said step of determining whether said number of readouts already executed on said stored data has reached said predetermined limiting number of readouts is achieved by a control means comprising; a subtracted circuit for subtracting a number of readouts already executed on said stored data from said predetermined limiting number of readouts; a memory means for memorizing said subtracted number; and a judging circuit for determine whether said subtracted number has reached said predetermined limiting number of readouts.
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26. A method of limiting a number of readouts of data stored in a semiconductor memory device comprised of a pair of bit lines, a word line, a cell plate electrode, a memory cell connected to said bit lines, said word line, and said cell plate electrode, wherein said limiting method comprises the steps of:
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determining a number of readouts already executed on said stored data; determining whether said number of readouts already executed on said stored data has reached a predetermined limiting number of readouts; preventing subsequent readouts of said stored data upon determination that said number of readouts already executed on said stored data has reached said predetermined limiting number of readouts, by altering bit line capacitance of at least one of said bit lines. - View Dependent Claims (27)
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28. A method of limiting a number of readouts of data stored in a semiconductor memory device comprised of a pair of bit lines, a word line, a cell plate electrode, a memory cell connected to said bit lines, said word line, and said cell plate electrode, wherein said limiting method comprises the steps of:
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determining a number of readouts already executed on said stored data; determining whether said number of readouts already executed on said stored data has reached a predetermined limiting number of readouts; preventing subsequent readouts of said stored data upon determination that said number of readouts already executed on said stored data has reached said predetermined limiting number of readouts, by equalizing logical voltage of said bit lines.
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Specification