MEMORY DEVICE, DISPLAY DEVICE EQUIPPED WITH MEMORY DEVICE, DRIVE METHOD FOR MEMORY DEVICE, AND DRIVE METHOD FOR DISPLAY DEVICE

• US 20120169753A1
• Filed: 04/23/2010
• Published: 07/05/2012
• Est. Priority Date: 09/16/2009
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Murakami, Yuhichiroh, Furuta, Shige, Sasaki, Yasushi, Gyouten, Seijirou, Nishi, Shuji
• Granted Patent: US 8,866,720 B2
• Time in Patent Office: Days
• US Class Current: 345/560
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0823 used to establish symmetry in driving, e.g. with polarity inversion
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2300/088 using a non-linear two-terminal element
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: G11C 11/405 with three charge-transfer gates, e.g. MOS transistors, per cell

Abstract

A memory device is provided which includes a memory circuit that allows a circuit which carries out a refresh operation to suitably carry out an original operation of the circuit even if an off-leakage current occurs in a transfer element used in a transfer section. A memory cell includes a switching circuit, a first retaining section, a transfer section, a second retaining section, a first control section, and a voltage supply, and the first control section is controlled to be in (i) a state in which the first control section carries out a first operation in which the first control section is in an active state or a non-active state and (ii) a state in which the first control section carries out a second operation.

Claims

1. A memory device comprising:

a memory array in which memory cells are provided in a matrix pattern;

a row driver which drives each row of the memory array;

a column driver which drives each column of the memory array;

a first wire which is provided for the each row and connects memory cells in an identical row;

a second wire and a third wire each of which connects the memory cells; and

a fourth wire which is provided for the each column and connects memory cells in an identical column, the fourth wire being driven by the column driver so that each of a first electric potential level and a second electric potential level each indicating a binary logic level is supplied to the fourth wire,

the memory cells of the memory array each including;

a switching circuit;

a first retaining section;

a transfer section;

a second retaining section; and

a first control section,

the switching circuit being driven by the row driver via the first wire, so as to selectively turn on/off between the fourth wire and the first retaining section,

the first retaining section retaining the binary logic level to be supplied thereto,

the transfer section being driven via the second wire, so as to selectively carry out (i) a transfer operation in which the binary logic level retained in the first retaining section is transferred to the second retaining section in a state in which the binary logic level remains retained in the first retaining section and (ii) a non-transfer operation in which no transfer operation is carried out,

the second retaining section retaining the binary logic level to be supplied thereto,

the first control section being driven via the third wire, so as to be selectively controlled to be in a state in which the first control section carries out a first operation or a second operation,

the first operation being an operation which is carried out by the first control section in (i) an active state in which the first control section receives an input thereto and supplies the input as an output thereof to the first retaining section or (ii) a non-active state in which the first control section stops carrying out an output, the active or non-active state having been selected in accordance with control information indicative of which of the first electric potential level and the second electric potential level is retained in the second retaining section as the binary logic level,

the second operation being an operation in which the first control section stops carrying out the output regardless of the control information, and

said memory device further comprising a voltage supply which supplies a set electric potential to an input of the first control section.

2. The memory device as set forth in claim 1, wherein:

the first control section includes;

a first switch which causes the binary logic level retained in the second retaining section to be a turning on/off control signal as the control information; and

a second switch which causes a signal to be supplied to the third wire to be a turning on/off control signal; and

the first switch and the second switch are connected in series to each other between the input of the first control section and an output of the first control section.

3. The memory device as set forth in claim 1, wherein:

in a writing mode in which the memory device writes data to a memory cell,

the memory device carries out a first step of (I) in a state in which (i) the binary logic level corresponding to the data is being supplied from the column driver to the fourth wire and (ii) the first control section is carrying out the second operation, causing the switching circuit to turn on, so as to write the binary logic level to the memory cell and (II) in a state in which (i) the binary logic level has been written to the memory cell and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation; and

the memory device carries out, at least one time, a series of operations, which are a second step following the first step, a third step following the second step, and a fourth step following the third step, from the start of the second step to the end of the fourth step,

in the second step, in a state in which (i) the first control section is carrying out the second operation and (ii) the transfer section is carrying out the non-transfer operation, the memory device causes the switching circuit to turn on, so as to supply, to the first retaining section via the fourth wire, the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the active state,

in the third step, in a state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the non-transfer operation, the memory device causes the first control section to carry out the first operation, and by the time the first operation is finished, the memory device causes the binary logic level to be supplied from the voltage supply to the input of the first control section, the binary logic level being inverse to the level that is equivalent to the control information which causes the first control section to be in the active state, and

in the fourth step, in a state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, the memory device causes the transfer section to carry out the transfer operation.

4. The memory device as set forth in claim 1, wherein:

the first retaining section includes a first capacitor whose one end serves as a retaining node which retains the binary logic level;

the second retaining section includes a second capacitor whose one end serves as a retaining node which retains the binary logic level;

the first capacitor has a larger capacitance than the second capacitor; and

the transfer section includes a third switch.

5. The memory device as set forth in claim 2, wherein:

the first retaining section includes a first capacitor whose one end serves as a retaining node which retains the binary logic level;

the second retaining section includes a second capacitor whose one end serves as a retaining node which retains the binary logic level;

the first capacitor has a larger capacitance than the second capacitor;

the transfer section includes a third switch; and

the switching circuit, the first switch, the second switch, and the third switch are N-channel field-effect transistors.

6. The memory device as set forth in claim 2, wherein:

the first retaining section includes a first capacitor whose one end serves as a retaining node which retains the binary logic level;

the second retaining section includes a second capacitor whose one end serves as a retaining node which retains the binary logic level;

the first capacitor has a larger capacitance than the second capacitor;

the transfer section includes a third switch; and

the switching circuit, the first switch, the second switch, and the third switch are P-channel field-effect transistors.

7. The memory device as set forth in claim 3, wherein:

the second wire serves also as the voltage supply; and

during the third step, the memory device supplies, to the second wire, the binary logic level which is inverse to the level that is equivalent to the control information which causes the first control section to be in the active state.

8. The memory device as set forth in claim 3, wherein:

the voltage supply is separately wired; and

during the third step, the memory device supplies, to the voltage supply, the binary logic level which is inverse to the level that is equivalent to the control information which causes the first control section to be in the active state.

9. The memory device as set forth in claim 3, wherein:

the second wire serves also as the third wire;

when the transfer section is in a state in which the transfer section carries out the transfer operation, the first control section is controlled to be in a state in which the first control section carries out the second operation, whereas, when the transfer section is in a state in which the transfer section carries out the non-transfer operation, the first control section is controlled to be in a state in which the first control section carries out the first operation;

the voltage supply is separately wired; and

during the third step, the memory device supplies, to the voltage supply, the binary logic level which is inverse to the level that is equivalent to the control information which causes the first control section to be in the active state.

10. The memory device as set forth in claim 3, wherein:

the first retaining section includes a first capacitor whose one end serves as a retaining node which retains the binary logic level;

the second retaining section includes a second capacitor whose one end serves as a retaining node which retains the binary logic level;

the first capacitor has a larger capacitance than the second capacitor;

the transfer section includes a third switch;

the memory device further includes a fifth wire which is provided for the each row of the memory array and is connected to the other end of the second capacitor of each of the memory cells in the identical row;

in the fourth step, a first period is set after the memory device temporarily causes the transfer section to carry out the transfer operation in the state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, the first period being a period in which the memory device subsequently causes the first control section to carry out the first operation in a state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the transfer operation;

in a case where the control information which causes the first control section to be in the active state when the first control section carries out the first operation is at a higher level of the first electric potential level and the second electric potential level, the memory device supplies, to the fifth wire, a pulse whose electric potential rises from a Low electric potential to a High electric potential; and

in a case where the control information which causes the first control section to be in the active state when the first control section carries out the first operation is at a lower level of the first electric potential level and the second electric potential level, the memory device supplies, to the fifth wire, a pulse whose electric potential falls from the High electric potential to the Low electric potential.

11. The memory device as set forth in claim 10, wherein in the first period, the memory device supplies, to the fourth wire, the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the non-active state when the first control section carries out the first operation.

12. The memory device as set forth in claim 1, wherein:

in a reading mode in which the memory device reads the data from the memory cell,

the memory device carries out a fifth step, a sixth step following the fifth step, and a seventh step following the sixth step,

in the fifth step, in a state in which (i) the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the active state is being supplied from the column driver to the fourth wire, (ii) the transfer section is carrying out the non-transfer operation, and (iii) the first control section is carrying out the second operation, the memory device causes the switching circuit to turn on, so as to write the binary logic level to the memory cell,

in the sixth step, in a state in which (i) the switching circuit is on and (ii) the transfer section is carrying out the non-transfer operation, the memory device causes the first control section to carry out the first operation, and

in the seventh step, in the state in which (i) the switching circuit is on and (ii) the transfer section is carrying out the non-transfer operation, the memory device causes the column driver to sense an electric potential of the fourth wire, so as to determine the data retained in the memory cell.

13. The memory device as set forth in claim 12, wherein:

following the seventh step, the memory device carries out an eighth step of, in the state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation; and

the memory device carries out, at least one time, a series of operations, which are a ninth step following the eighth step, a tenth step following the ninth step, and an eleventh step following the tenth step, from the start of the ninth step to the end of the eleventh step,

in the ninth step, in a state in which (i) the transfer section is carrying out the non-transfer operation, (ii) the binary logic level which is equal to the level that is equivalent to the control information which causes the first control section to be in the active state is being supplied from the column driver to the fourth wire, and (iii) the first control section is carrying out the second operation, the memory device causes the switching circuit to turn on,

in the tenth step, in the state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the non-transfer operation, the memory device causes the first control section to carry out the first operation, and

in the eleventh step, in the state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, the memory device causes the transfer section to carry out the transfer operation.

14. A display device comprising:

a memory device recited in claim 1,

the first retaining section including a liquid crystal capacitor of a pixel electrode connected to the retaining node of the first retaining section, the retaining node retaining the binary logic level,

the first wire serving also as a scanning signal line, and the fourth wire serving also as a data signal line, and

the display device causing the row driver to drive the switching circuit via the first wire and supplying a data signal from the column driver via the fourth wire and the switching circuit to the first retaining section, so as to apply a voltage to the liquid crystal capacitor and to carry out a display.

15. The display device as set forth in claim 14, wherein the display device carries out a first display mode in which the binary logic level is supplied as the data signal to the memory cell so that the display is carried out.

16. The display device as set forth in claim 15, wherein:

in the first display mode,

the display device carries out a step A of (I) in a state in which (i) the binary logic level corresponding to the data signal is being supplied from the column driver to the fourth wire and (ii) the first control section is carrying out the second operation, causing the switching circuit to turn on, so as to write the binary logic level to the memory cell and (II) in a state in which (i) the binary logic level has been written to the memory cell and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation; and

the display device carries out, at least one time, a series of operations, which are a step B following the step A, a step C following the step B, and a step D following the step C, from the start of the step B to the end of the step D,

in the step B, in a state in which (i) the first control section is carrying out the second operation and (ii) the transfer section is carrying out the non-transfer operation, the display device causes the switching circuit to turn on, so as to supply, to the first retaining section via the fourth wire, the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the active state,

in the step C, in a state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the non-transfer operation, the display device causes the first control section to carry out the first operation, and by the time the first operation is finished, the display device causes the binary logic level to be supplied from the voltage supply to the input of the first control section, the binary logic level being inverse to the level that is equivalent to the control information which causes the first control section to be in the active state, and

in the step D, in a state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, the display device causes the transfer section to carry out the transfer operation.

17. The display device as set forth in claim 15, wherein the display device carries out alternating-current driving in which a common electrode of the liquid crystal capacitor is inverted between binary levels.

18. The display device as set forth in claim 17, wherein the binary levels to be supplied to the common electrode are the first electric potential level and the second electric potential level.

19. The display device as set forth in claim 17, wherein the binary levels to be supplied to the common electrode are inverted only in a period in which the switching circuit is on.

20. The display device as set forth in claim 14, wherein:

the column driver is capable of supplying, to the fourth wire, a multilevel data signal which is the data signal whose electric potential levels are larger in number than the binary levels; and

the display device carries out a second display mode in which the multilevel data signal is supplied to the memory cell so that the display is carried out in a state in which the first control section does not carry out the first operation in which the first control section is in the active state.

21. The display device as set forth in claim 14, wherein the first retaining section serves also as a storage capacitor.

22. A memory device driving method for writing data to the memory device recited in claim 1,

said memory device driving method comprising:

carrying out a first step of (I) in a state in which (i) the binary logic level corresponding to the data is being supplied from the column driver to the fourth wire and (ii) the first control section is carrying out the second operation, causing the switching circuit to turn on, so as to write the binary logic level to the memory cell and (II) in a state in which (i) the binary logic level has been written to the memory cell and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation; and

carrying out, at least one time, a series of operations, which are a second step following the first step, a third step following the second step, and a fourth step following the third step, from the start of the second step to the end of the fourth step,

the second step, in a state in which (i) the first control section is carrying out the second operation and (ii) the transfer section is carrying out the non-transfer operation, causing the switching circuit to turn on, so as to supply, to the first retaining section via the fourth wire, the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the active state,

the third step, in a state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the non-transfer operation, causing the first control section to carry out the first operation, and by the time the first operation is finished, causing the binary logic level to be supplied from the voltage supply to the input of the first control section, the binary logic level being inverse to the level that is equivalent to the control information which causes the first control section to be in the active state, and

the fourth step, in a state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation.

23. A memory device driving method for reading the data from the memory device recited in claim 1,

said memory device driving method comprising:

carrying out a fifth step, a sixth step following the fifth step, and a seventh step following the sixth step,

the fifth step, in a state in which (i) the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the active state is being supplied from the column driver to the fourth wire, (ii) the transfer section is carrying out the non-transfer operation, and (iii) the first control section is carrying out the second operation, causing the switching circuit to turn on, so as to write the binary logic level to the memory cell,

the sixth step, in a state in which (i) the switching circuit is on and (ii) the transfer section is carrying out the non-transfer operation, causing the first control section to carry out the first operation, and

the seventh step, in the state in which (i) the switching circuit is on and (ii) the transfer section is carrying out the non-transfer operation, causing the column driver to sense an electric potential of the fourth wire, so as to determine the data retained in the memory cell.

24. The memory device driving method as set forth in claim 23, comprising:

following the seventh step, carrying out an eighth step of, in the state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation; and

carrying out, at least one time, a series of operations, which are a ninth step following the eighth step, a tenth step following the ninth step, and an eleventh step following the tenth step, from the start of the ninth step to the end of the eleventh step,

the ninth step, in a state in which (i) the transfer section is carrying out the non-transfer operation, (ii) the binary logic level which is equal to the level that is equivalent to the control information which causes the first control section to be in the active state is being supplied from the column driver to the fourth wire, and (iii) the first control section is carrying out the second operation, causing the switching circuit to turn on,

the tenth step, in the state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the non-transfer operation, causing the first control section to carry out the first operation, and

the eleventh step, in the state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation.

25. A display device driving method for carrying out a display by writing the data signal to the display device recited in claim 14,

said display device driving method comprising:

carrying out a step A of (I) in a state in which (i) the binary logic level corresponding to the data signal is being supplied from the column driver to the fourth wire and (ii) the first control section is carrying out the second operation, causing the switching circuit to turn on, so as to write the binary logic level to the memory cell and (II) in a state in which (i) the binary logic level has been written to the memory cell and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation; and

carrying out, at least one time, a series of operations, which are a step B following the step A, a step C following the step B, and a step D following the step C, from the start of the step B to the end of the step D,

the step B, in a state in which (i) the first control section is carrying out the second operation and (ii) the transfer section is carrying out the non-transfer operation, causing the switching circuit to turn on, so as to supply, to the first retaining section via the fourth wire, the binary logic level which is equal to a level that is equivalent to the control information which causes the first control section to be in the active state,

the step C, in a state in which (i) the switching circuit is off and (ii) the transfer section is carrying out the non-transfer operation, causing the first control section to carry out the first operation, and by the time the first operation is finished, causing the binary logic level to be supplied from the voltage supply to the input of the first control section, the binary logic level being inverse to the level that is equivalent to the control information which causes the first control section to be in the active state, and

the step D, in a state in which (i) the switching circuit is off and (ii) the first control section is carrying out the second operation, causing the transfer section to carry out the transfer operation.

26. The display device driving method as set forth in claim 25, further comprising carrying out alternating-current driving in which a common electrode of the liquid crystal capacitor is inverted between binary levels.

27. The display device driving method as set forth in claim 26, wherein the binary levels to be supplied to the common electrode are the first electric potential level and the second electric potential level.

28. The display device driving method as set forth in claim 26, wherein the binary levels to be supplied to the common electrode are inverted only in a period in which the switching circuit is on.

29. The display device driving method as set forth in claim 25, further comprising carrying out a second display mode in which a multilevel data signal is supplied from the column driver to the memory cell so that the display is carried out in a state in which the first control section does not carry out the first operation in which the first control section is in the active state, the multilevel data signal being the data signal whose electric potential levels are larger in number than the binary levels, the column driver being capable of supplying the multilevel data signal to the fourth wire.