System and method for discarding data bits during display modulation
View Patent ↗A novel method for asynchronously driving a display device including a plurality of pixels arranged in a plurality of columns and a plurality of rows includes the steps of receiving a first multi-bit data word indicative of a first grayscale value to be displayed on a pixel of a first row of the display, defining a first time period during which an electrical signal corresponding to the first grayscale value can be asserted on the pixel of said first row, receiving a second multi-bit data word indicative of a second grayscale value to be displayed on a pixel of a second row of the display, and defining a second time period that is temporally offset from the first time period during which an electrical signal corresponding to the second grayscale value can be asserted on the pixel of said second row. A novel display driver for performing the methods of the present invention is also disclosed.
1. A method for driving a display device, said method comprising:
receiving a multibit data word indicative of an intensity value to be asserted on a pixel of said display during a predefined modulation period;
initializing an electrical signal on said pixel during said modulation period at a first time depending on the value of at least one of the bits of said multibit data word;
discarding said at least one bit of said multibit data word; and
terminating said electrical signal on said pixel at a second time during said modulation period and after said step of discarding said at least one bit of said multibit data word, said second time determined from any remaining bits of said multibit data word such that the duration from said first time to said second time that said electrical signal is asserted on said pixel corresponds to said intensity value.
2. A method according to claim 1 , further comprising:
dividing said modulation period into a plurality of coequal time intervals; and
discarding said bits of said multibit data word after respective predetermined numbers of said coequal time intervals.
3. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 2 .
4. A method according to claim 1 , further comprising dividing said modulation period into (2 n −1) coequal time intervals, where n equals the number of bits in said multibit data word.
5. A method according to claim 4 , further comprising discarding particular bits of said multibit data word after the lapse of respective predetermined numbers of said time intervals.
6. A method according to claim 5 , further comprising:
defining a group of x consecutive bits of said multibit data word, said group of x consecutive bits including a least significant bit of said multibit data word, x being an integer less than n; and
discarding said group of said consecutive bits after the lapse of (2 x −1) said time intervals.
7. A method according to claim 6 , further comprising:
defining a second group of bits including said bits of said multibit data word not included in said first group of bits; and
discarding the bits of said second group in order from most to least significance.
8. A method according to claim 7 , further comprising:
discarding a b th most significant bit of said second group of bits after the lapse of (2 n −2 n−b ) ones of said time intervals; and wherein
b is an integer greater than or equal to one and less than or equal to (n−x).
9. A method according to claim 8 , wherein said multibit data word contains eight bits and said group of consecutive bits includes said least significant bit and a next least significant bit of said multibit data word, said method comprising:
discarding said least significant bit and said next least significant bit after the lapse of three of said time intervals;
discarding a most significant bit of said second group of bits after the lapse of one-hundred twenty-eight of said time intervals;
discarding a second most significant bit of said second group of bits after the lapse of one-hundred and ninety-two of said time intervals;
discarding a third most significant bit of said second group of bits after the lapse of two-hundred and twenty-four of said time intervals;
discarding a fourth most significant bit of said second group of bits after the lapse of two-hundred and forty of said time intervals;
discarding a fifth most significant bit of said second group of bits after the lapse of two-hundred and forty-eight of said time intervals; and
discarding a last bit of said second group of bits after the lapse of two-hundred and fifty-two of said time intervals.
10. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 9 .
11. A method according to claim 8 , wherein said multibit data word contains eight bits and said group of consecutive bits includes said least significant bit, a next least significant bit, and a second next least significant bit of said multibit data word, said method comprising:
discarding said least significant bit, said next least significant bit, and said second next least significant bit after the lapse of seven of said time intervals;
discarding a most significant bit of said second group of bits after the lapse of one-hundred and twenty eight of said time intervals;
discarding a second most significant bit of said second group of bits after the lapse of one-hundred and ninety-two of said time intervals;
discarding a third most significant bit of said second group of bits after the lapse of two-hundred and twenty-four of said time intervals;
discarding a fourth most significant bit of said second group of bits after the lapse of two-hundred and forty of said time intervals; and
discarding a last bit of said second group of bits after the lapse of two-hundred and forty-eight of said time intervals.
12. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 11 .
13. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 8 .
14. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 7 .
15. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 6 .
16. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 5 .
17. A method according to claim 4 , further comprising providing a series of time values each associated with one of said time intervals.
18. A method according to claim 17 , further comprising evaluating particular ones of said bits of said multibit data word based on said time values.
19. A method according to claim 18 , wherein said pixel is located in a particular row of said display, and said method further includes adjusting the value of said time values based on said particular row prior to said step of evaluating said particular ones of said bits.
20. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 19 .
21. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 18 .
22. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 17 .
23. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 4 .
24. A method according to claim 1 , further comprising:
reading a value currently being asserted on said pixel; and
using said read value to determine a next value to be asserted on said pixel.
25. A method according to claim 24 , further comprising using said read value in combination with said remaining bits of said multibit data word to update the electrical signal being asserted on said pixel.
26. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 25 .
27. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 24 .
28. A method according to claim 1 , further comprising:
storing each bit of said multibit data word in a memory device; and wherein
said step of discarding said at least one bit of said multibit data word includes over-writing said at least one bit with a bit of a subsequent multibit data word associated with another pixel of said display.
29. A method according to claim 28 , further comprising providing said memory device with a sufficient amount of memory such that each bit of said multibit data word is stored in said memory long enough to be asserted on said pixel, said memory device having a capacity of less than one frame of data.
30. A method according to claim 29 , further comprising:
dividing said modulation period into (2 n −1) coequal time intervals;
discarding each bit of said multibit data word after the lapse of a predetermined number of said time intervals; and
providing storage for
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bits of data in said memory device; and where r equals the number of rows in said display, c equals the number of columns in said display, n equals the number of bits in said multibit data word, B i represents each particular bit of said multibit data word, T D equals said predetermined number of said time intervals after the lapse of which an associated bit can be discarded, INT is the integer function, and MOD is the remainder function.
31. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 30 .
32. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 29 .
33. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 28 .
34. A method according to claim 1 , wherein said step of discarding said at least one bit includes ignoring an invalid data bit.
35. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 34 .
36. A method according to claim 1 , further comprising:
dividing said modulation period into a plurality of coequal time intervals;
updating said electrical signal asserted on said pixel during each of a plurality of consecutive ones of said time intervals during a first portion of said modulation period; and
updating said electrical signal asserted on said pixel every m th one of said time intervals during a second portion of said modulation period, m being an integer greater than one.
37. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 36 .
38. A method according to claim 1 , further comprising:
dividing said modulation period into a plurality of coequal time intervals;
asserting said electrical signal on said pixel in a first bias direction for a first group of said coequal time intervals; and
asserting said electrical signal on said pixel in a second bias direction for a second group of said coequal time intervals.
39. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 38 .
40. An electronically readable medium having code embodied therein for causing an electronic device to perform the method of claim 1 .
41. A method according to claim 1 , further comprising:
storing each bit of said multibit data word in a memory device at or before the beginning of said modulation period; and
wherein said memory device has a capacity of less than one frame of data.
42. A method according to claim 1 , further comprising:
storing at least one bit of said multibit data word in a memory device at a first storage time during said modulation period; and
storing at least one other bit of said multibit data word in said memory device at a second storage time during said modulation period; and
wherein said memory device has a capacity of less than one frame of data.
43. A method according to claim 42 , further comprising:
dividing said modulation period into at least (2 n −1) coequal time intervals, where n equals the number of bits in said multibit data word;
defining a group of x consecutive bits of said multibit data word, said group of x consecutive bits including a least significant bit of said multibit data word, x being an integer less than n; and
storing said group of x consecutive bits of said multibit data word in said memory device at said first storage time, said first storage time occurring during or prior to a first one of said coequal time intervals in said modulation period.
44. A method according to claim 43 , further comprising:
defining a second group of bits including said bits of said multibit data word not included in said first group of bits; and
storing said second group bits of said multibit data word in said memory device at said second storage time, said second storage time occurring during or after the (2 x −1) one said time intervals.
45. A display driver comprising:
a data input terminal set for receiving a multibit data word, said multibit data word indicative of an intensity value to be displayed on a pixel of said display during a predefined modulation period;
an output terminal set selectively coupled to said pixel; and
control logic operative
to initialize an electrical signal on said pixel during said modulation period at a first time depending on the value of at least one of the bits of said multibit data word;
to discard said at least one bit of said multibit data word; and
to terminate said electrical signal on said pixel at a second time during said modulation period and after said step of discarding said at least one bit of said multibit data word, said second time determined from any remaining bits of said multibit data word such that the duration from said first time to said second time that said electrical signal is asserted on said pixel corresponds to said intensity value.
46. A display driver according to claim 45 , wherein said control logic is further operative to divide said modulation period into a plurality of coequal time intervals and to discard said bits of said multibit data word after respective predetermined numbers of said coequal time intervals.
47. A display driver according to claim 45 , wherein said control logic is further operative to divide said modulation period into (2 n −1) coequal time intervals, where n equals the number of bits in said multibit data word.
48. A display driver according to claim 47 , wherein said control logic is further operative to discard particular bits of said multibit data word after the lapse of respective predetermined numbers of said time intervals.
49. A display driver according to claim 48 wherein said control logic is further operative to:
define a group of x consecutive bits of said multibit data word, said group of x consecutive bits including a least significant bit of said multibit data word, x being an integer less than n; and
discard said group of consecutive bits after the lapse of the first (2 x −1) said time intervals.
50. A display driver according to claim 49 , wherein said control logic is further operative to:
define a second group of bits including said bits of said multibit data word not included in said first group of bits; and
discard the bits of said second group in order from most to least significance.
51. A display driver according to claim 50 , wherein said control logic is further operative to:
discard a b th most significant bit of said second group of bits after the lapse of (2 n −2 n−b ) ones of said time intervals; and wherein
b is an integer greater than or equal to one and less than or equal to (n−x).
52. A display driver according to claim 51 , wherein:
said multibit data word contains eight bits;
said group of consecutive bits includes said least significant bit and a next least significant bit of said multibit data word; and
said control logic is operative to
discard said least significant bit and said next least significant bit after the lapse of three of said time intervals;
discard a most significant bit of said second group of bits after the lapse of one-hundred and twenty-eight of said time intervals;
discard a second most significant bit of said second group of bits after the lapse of one-hundred and ninety-two of said time intervals;
discard a third most significant bit of said second group of bits after the lapse of two-hundred and twenty-four of said time intervals;
discard a fourth most significant bit of said second group of bits after the lapse of two-hundred and forty of said time intervals;
discard a fifth most significant bit of said second group of bits after the lapse of two-hundred and forty-eight of said time intervals; and
discard a last bit of said second group of bits after the lapse of two-hundred and fifty-two of said time intervals.
53. A display driver according to claim 51 , wherein:
said multibit data word contains eight bits;
said group of consecutive bits includes said least significant bit, a next least significant bit, and a second next least significant bit of said multibit data word; and
said control logic is operative to
discard said least significant bit, said next least significant bit, and said second next least significant bit after the lapse of seven of said time intervals;
discard a most significant bit of said second group of bits after the lapse of one-hundred and twenty-eight of said time intervals;
discard a second most significant bit of said second group of bits after the lapse of one-hundred and ninety-two of said time intervals;
discard a third most significant bit of said second group of bits after the lapse of two-hundred and twenty-four of said time intervals;
discard a fourth most significant bit of said second group of bits after the lapse of two-hundred and forty of said time intervals; and
discard a last bit of said second group of bits after the lapse of two-hundred and forty-eight of said time intervals.
54. A display driver according to claim 47 , further comprising a timer for generating a series of time values each associated with of one of said time intervals.
55. A display driver according to claim 54 , wherein said control logic is further operative to evaluate particular bits of said multibit data word based on said time values.
56. A display driver according to claim 55 , wherein:
said pixel is located in a particular row of said display; and
said control logic is further operative to adjust said time values based on said particular row prior to evaluating said particular bits.
57. A display driver according to claim 45 , wherein said control logic is further operative to:
read a value currently being asserted on said pixel; and
use said read value to determine a next value to be asserted on said pixel.
58. A display driver according to claim 57 , wherein said control logic is further operative to use said read value in combination with said remaining bits of said multibit data word to update the electrical signal being asserted on said pixel.
59. A display driver according to claim 45 , further comprising a memory device operative to:
receive said multibit data word;
temporarily store said multibit data word;
provide said multibit data word to said control logic; and
overwrite at least one bit of said multibit data word with a bit of a subsequent multibit data word while retaining other bits of said multibit data word needed for subsequent pixel updates.
60. A display driver according to claim 59 , wherein said memory device has a capacity sufficient to store each of said bits of said multibit data word long enough for said control logic to initiate and terminate said electrical signal on said pixel, said capacity being less than one frame of data.
61. A display driver according to claim 60 , wherein:
said control logic is further operative to
divide said modulation period into (2 n −1) coequal time intervals, and
discard each bit of said multibit data word after the lapse of a predetermined number of said time intervals;
said memory device provides storage for
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bits of data, where r equals the number of rows in said display, c equals the number of columns in said display, n equals the number of bits in said multibit data word, B i represents each bit of said multibit data word, T D equals said predetermined number of said time intervals after the lapse of which an associated bit can be discarded, INT is the integer function, and MOD is the remainder function.
62. A display driver according to claim 45 , wherein said control logic is operative to discard said at least one bit by ignoring an invalid data bit.
63. A display driver according to claim 45 , wherein said control logic is further operative to:
divide said modulation period into a plurality of coequal time intervals;
update said electrical signal asserted on said pixel during each of a plurality of consecutive ones of said time intervals during a first portion of said modulation period; and
update said electrical signal asserted on said pixel every m th one of said time intervals during a second portion of said modulation period, m being an integer greater than one.
64. A display driver according to claim 45 , wherein said control logic is further operative to:
divide said modulation period into a plurality of coequal time intervals;
assert said electrical signal on said pixel in a first bias direction for a first group of said coequal time intervals, and
assert said electrical signal on said pixel in a second bias direction for a second group of said coequal time intervals.
65. A display driver according to claim 45 , further comprising a memory device operative to:
receive at least one bit of said multibit data word;
temporarily store said at least one bit of said multibit data word at a first storage time during said modulation period;
receive at least one other bit of said multibit data word;
temporarily store said at least one other bit of said multibit data word at a second storage time during said modulation period; and
provide said multibit data word to said control logic; and
wherein said memory device has a capacity of less than one frame of data.
66. A display driver according to claim 65 , wherein:
said control logic is further operative to
divide said modulation period into at least (2 n −1) coequal time intervals, where n equals the number of bits in said multibit data word, and
define a group of x consecutive bits of said multibit data word, said group of x consecutive bits including a least significant bit of said multibit data word, x being an integer less than n; and
said memory device is further operative to store said group of x consecutive bits of said multibit data word in said memory device at said first storage time, said first storage time occurring during or prior to a first one of said coequal time intervals in said modulation period.
67. A display driver according to claim 66 , wherein:
said control logic is further operative to define a second group of bits including said bits of said multibit data word not included in said first group of bits; and
said memory device is further operative to store said second group bits of said multibit data word in said memory device at said second storage time, said second storage time occurring during or after the (2 x −1) one said time intervals.
68. A display driver comprising:
an input terminal set for receiving multibit image data;
an output terminal set selectively coupled to a pixel of said display; and
control logic operative to assert an electrical pulse on said pixel during a predefined time period such that the duration of said pulse corresponds to an intensity value indicated by said multibit image data; and
means for discarding at least one bit of said multibit image data prior to determining when to terminate said electrical pulse; and wherein
said control logic determines when to terminate said electrical pulse based on any remaining bits of said multibit image data.