Liquid crystal display device having a liquid crystal display driven by interlace scanning and/or sequential scanning

• US 20060012556A1
• Filed: 08/10/2005
• Published: 01/19/2006
• Est. Priority Date: 03/01/2000
• Status: Active Grant

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Asai, Katsuhiko, Kondo, Takashi, Okumura, Kazuaki, Mandai, Makiko, Nakai, Masaaki, Yoneda, Shuji, Kohriyama, Koichi, Hotomi, Hideo, Hashimoto, Kiyofumi, Yamakawa, Eiji, Masazumi, Naoki, Ochi, Keizou
• Granted Patent: US 7,679,593 B2
• Time in Patent Office: Days
• US Class Current: 345/98
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2300/0486 Cholesteric liquid crystals, including chiral-nematic liquid crystals, with transitions between focal conic, planar, and homeotropic states
• CPC Class Codes: G09G 2310/0227 related to multiple interlacing, i.e. involving more fields than just one odd field and one even field
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 3/3629 using liquid crystals having memory effects, e.g. ferroelectric liquid crystals

Abstract

A display device which has a liquid crystal display which has a plurality liquid crystal pixels arranged in a matrix and which writes an image thereon after resetting the liquid crystal. The method of writing on the liquid crystal display can be selected from driving methods according to interlace scanning in which a frame is divided into a plurality of fields and writing by interlace scanning is performed and driving methods according to sequential scanning in which scanning lines are subjected to writing serially. When high-speed writing is required, for example, when display of a motion picture, display of inputted letters or scroll display is desired, one of the driving methods according to interlace scanning is selected. In interlace scanning, based on the end of a blackout state of a scanning line in a field, selection of a scanning line in the next field for writing is started. Writing on a scanning line comprises a reset step of resetting the liquid crystal, a selection step of selecting the final state of the liquid crystal, an evolution step of stabling the liquid crystal into the selected state, and one of the length of the reset step and the total length of the selection step and the evolution step is n times (n: natural number) the other. For example, when the length of the reset step is n times the total length of the selection step and the evolution step and when a frame is divided into m fields (m: natural number larger than n) for interlace scanning, there is a moment when, in serial m scanning lines, n scanning lines of them are in the reset step, one of them is in the selection step or in the evolution step, and the other m-n-l scanning lines are in a display step.

Claims

1-24. -24. (canceled)

25. A display device comprising:

a liquid crystal display comprising a plurality of scanning lines, a plurality of data lines which cross the scanning lines, and chiral nematic liquid crystal provided between the scanning lines and the data lines, the scanning lines and the data lines defining a plurality of pixels arranged in a matrix, the liquid crystal being capable of displaying an image thereon continuously while no voltages are applied to the scanning lines and the data lines, and the liquid crystal performing selective reflection in a cholesteric phase;

a driver which is connected to the scanning lines and the data lines and which carries out writing in a first display area of the liquid crystal display and writing in a second display area of the liquid crystal display independently of each other in a predetermined display mode, wherein the first display area and the second display area are separated by a specified scanning line as a border, and in said predetermined display mode, the driver carries out writing by interlace scanning repeatedly in a plurality of fields into which each frame is divided, wherein said specified scanning line is changeable, and wherein said driver drives the liquid crystal display with a driving waveform including a reset step of resetting the liquid crystal into a homeotropic state, a selection step of selecting a final state of the liquid crystal, and an evolution step of establishing the final state of the liquid crystal;

an operation member to be used by an operator; and

a controller for controlling the driver to start an interlace scanning drive in response to operation of the operation member,

wherein the liquid crystal keeps displaying an image thereon using a memory effect until interlace scanning is started, and

wherein, in the area other than the area that is subjected to interlace scanning, the liquid crystal keeps displaying an image thereon using the memory effect.

27. The display device according to claim 25, wherein the controller controls the driver to continue the interlace scanning drive for a specified time after the operation of the operation member.

28. The display device according to claim 27, wherein the controller controls the driver to stop the interlace scanning drive when the specified time has passed since the operation of the operation member.

29. The display device according to claim 25, wherein the controller controls the driver to continue the interlace scanning drive while the operation member is being operated.

44. The display device according to claim 25, wherein:

either one of the reset step or a total of the selection step and the evolution step has a length of time which is n times as long as the other, in which n is a natural number;

or

either one of a total of the reset step and the selection step or the evolution step has a length of time which is n times as long as the other, in which n is a natural number.

45. The display device according to claim 25, wherein:

the driver uses one of a length of the reset step, a total length of the selection step and the evolution step, a total length of the reset step and the selection step, and a length of the evolution step as a unit length; and

when a length of time which is k times the unit length has passed since a start of the selection step of a scanning line, the driver starts the selection step of a next scanning line for writing, in which k is a natural number.

46. The display device according to claim 25, wherein the driver carries out writing by interlace scanning by dividing the frame into a plurality of fields.

47. The display device according to claim 46, wherein:

the driver uses one of a length of the reset step, a total length of the selection step and the evolution step, a total length of the reset step and the selection, and a length of the evolution step as a unit length; and

when a length of time which is k times the unit length has passed since a start of the selection step of a scanning line, the driver starts the selection step of a next scanning line for writing, in which k is a natural number.

48. The display device according to claim 25, wherein:

the driver carries out writing by interlace scanning by dividing a frame into m fields, in which m is a natural number larger than n;

a length of the reset step is n times a total length of the selection step and the evolution step; and

the writing comprises a moment when in serial m scanning lines, n scanning lines of them are in the reset step, one of them is in the selection step or in the evolution step, and the other m-n-l scanning lines are in a display step.

49. The display device according to claim 25, wherein:

the driver carries out writing by interlace scanning by dividing a frame into m fields, in which m is a natural number larger than n;

a total length of the selection step and the evolution step is n times a length of the reset step; and

the writing comprises a moment when in serial m scanning lines, one of them is in the reset step, n scanning lines of them are in the selection step or in the evolution step, and the other m-n-l scanning lines are in a display step.

50. The display device according to claim 25, wherein:

the driver carries out writing by interlace scanning by dividing a frame into m fields, in which m is a natural number larger than n;

a total length of the reset step and the selection step is n times a length of the evolution step; and

the writing comprises a moment when in serial m scanning lines, n scanning lines of them are in the reset step or in the selection step, one of them is in the evolution step, and the other m-n-l scanning lines are in a display step.

51. The display device according to claim 25, wherein:

the driver carries out writing by interlace scanning by dividing a frame into m fields, in which m is a natural number larger than n;

a length of the evolution step is n times a total length of the reset step and the selection step; and

the writing comprises a moment when in serial m scanning lines, one of them is in the reset step or in the selection step, n scanning lines of them are in the evolution step, and the other m-n-l scanning lines are in a display step.

52. The display device according to claim 46, wherein when a blackout state of a specified scanning line in a field ends, the driver starts the selection step of a first scanning line in a next field for writing.

53. The display device according to claim 52, wherein the specified scanning line in the field is the first scanning line in the next field for writing.

54. The display device according to claim 46, wherein the driver extends an evolution step of each scanning line in a field at least to a start of writing on each scanning line in a next field so as to keep the liquid crystal of each scanning line in a blackout state at least until the start of writing in the next field.

55. The display device according to claim 46, further comprising a controller that controls the driver to write a new piece of frame data in every field.

56. The display device according to claim 46, further comprising a controller which, when writing is carried out by dividing a frame into m fields, controls the driver to write a new piece of frame data in every m fields.

57. The display device according to claim 46, further comprising:

a selector for selecting a length for a cycle of writing a frame from a first frame length and a second frame length which is longer than the first frame length; and

a controller for controlling the driver to carry out writing at cycles of the selected frame length.

58. The display device according to claim 46, further comprising a selector for selecting a driving method from a plurality of driving methods, the driving methods including interlace scanning.

26. (canceled)

30-43. -43. (canceled)