Liquid crystal display device having a plurality of scanning methods

• US 5,754,160 A
• Filed: 04/12/1995
• Issued: 05/19/1998
• Est. Priority Date: 04/18/1994
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Usami, Hiroaki, Shimizu, Masayuki
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LAO, LUNYI
• Application Number:
  US08/420,411
• Time in Patent Office: 1,133 Days
• Field of Search: 348/446, 348/447, 348/443, 348/448, 348/790-792, 348/793, 348/714, 348/718-719, 348/589, 348/600, 395/152, 345/132, 345/87, 345/94, 345/95, 345/96, 345/103, 345/204, 345/208, 345/209, 345/210, 345/122, 345/115, 345/116, 345/119
• US Class Current: 345/103
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 3/3644 with the matrix divided into sections
• CPC Class Codes: G09G 3/3681 suitable for passive matrices only

Abstract

The present invention relates to a liquid crystal display device in which a liquid crystal display panel is divided into a plurality of areas and the number of common lines scanned at once is changed for each of the areas. More specifically, the liquid crystal display panel is divided into a 2α drive area and a 1α drive area. Based on a CDB signal, a scanning circuit selects and scans two common lines at once in the 2α drive area and shifts the selected two lines one by one. The scanning circuit selects and scans one common line in the 1α drive area and shifts the selected line one by one.

Claims

1. A liquid crystal display device for displaying an image of one frame formed of a first field and a second field, the display device comprising:

a liquid crystal display panel including a plurality of scanning lines and a plurality of segment lines formed in a matrix, and having a first display area with a first number of scanning lines and a second display area with a second number of scanning lines which is smaller than the first number of scanning lines;

display data supply means for supplying a segment drive signal corresponding to display data to the segment lines of said liquid crystal display panel;

first scanning means for supplying to the first display area a first scanning signal for simultaneously scanning at least two scanning lines during one scanning line period such that at least one scanning line is shifted to a next scanning line period; and

second scanning means for, after the first number of scanning lines in the first display area are scanned, supplying to the second display area a second scanning signal for scanning at least one scanning line during one scanning line period such that at least one scanning line is shifted to a next scanning line period, the second scanning signal having a selection period other than a selection period of the first scanning signal output from said first scanning means.

2. The device according to claim 1, wherein said first scanning means supplies the first scanning signal having a selection period of at least two horizontal scanning lines to one scanning line, and said second scanning means supplies the second scanning signal having a selection period of at least one horizontal scanning line to one scanning line.

3. The device according to claim 2, wherein said plurality of scanning lines are scanned in sequence, in response to the first and second scanning signals output from said first and second scanning means, while the selection period of said at least one horizontal scanning line is shifted every scanning of at least one of the scanning lines.

4. The device according to claim 2, wherein the first and second scanning signals output from said first and second scanning means have polarities which are inverted for each of the first and second fields.

5. The device according to claim 1, wherein said first scanning means supplies the first scanning signal to the first display area in the first field, and supplies a third scanning signal thereto in the second field, the third scanning signal having a selection period of at least one scanning line other than the selection period of the first scanning signal.

6. The device according to claim 1, wherein said first scanning means comprises odd-numbered line scanning means for scanning odd-numbered scanning lines of the first display area and even-numbered line scanning means for scanning even-numbered scanning lines of the first display area, said odd-numbered line scanning means supplies the first scanning signal to the odd-numbered scanning lines of the first display area, and said even-numbered line scanning means supplies a third scanning signal to the even-numbered scanning lines of the first display area, the third scanning signal having a selection period of at least one scanning line other than the selection period of the first scanning signal.

7. The device according to claim 6, wherein said odd-numbered line scanning means outputs the third scanning signal in the first field and the first scanning signal in the second field, and said even-numbered line scanning means outputs, the first scanning signal in the first field and the third scanning signal in the second field.

8. The device according to claim 1, wherein said second scanning means supplies the second scanning signal to the second display area in the first field and supplies a fourth scanning signal thereto in the second field, the fourth scanning signal having a selection period of at least one horizontal scanning line other than the selection period of the second scanning signal.

9. The device according to claim 1, wherein said second scanning means comprises odd-numbered line scanning means for scanning odd-numbered scanning lines of the second display area and even-numbered line scanning means for scanning even-numbered scanning lines of the second display area, said odd-numbered line scanning means supplies the second scanning signal to the odd-numbered scanning lines of the second display area, and said even-numbered line scanning means supplies a fourth scanning signal to the even-numbered scanning lines of the second display area, the fourth scanning signal having a selection period of at least one scanning line other than the selection period of the second scanning signal.

10. The device according to claim 9, wherein said odd-numbered line scanning means outputs the second scanning signal in the first field and the fourth scanning signal in the second field, and said even-numbered line scanning means outputs the fourth scanning signal in the first field and the second scanning signal in the second field.

11. The device according to claim 1, wherein said first scanning means supplies a fifth scanning signal having a selection period of three scanning lines in the first and second fields, said second scanning means comprises odd-numbered line scanning means for scanning odd-numbered scanning lines of the second display area and even-numbered line scanning means for scanning even-numbered scanning lines of the second display area, said odd-numbered line scanning means supplies the second scanning signal to the odd-numbered scanning lines of the second display area, and said even-numbered line scanning means supplies a fourth scanning signal to the even-numbered scanning lines of the second display area, the fourth scanning signal having a selection period of at least one scanning line other than the selection period of the second scanning signal.

12. The device according to claim 11, wherein the odd-numbered line scanning means of said second scanning means outputs the second scanning signal in the first field and the fourth scanning signal in the second field, and the even-numbered line scanning means of said second scanning means outputs the fourth scanning signal in the first field and the second scanning signal in the second field.

13. A liquid crystal display device for displaying an image of one frame formed of a first field and a second field, the display device comprising:

a liquid crystal display panel including a plurality of scanning lines and a plurality of segment lines formed in a matrix, and having a first display area and a second display area;

display data supply means for supplying a segment drive signal corresponding to display data to the segment lines of said liquid crystal display panel;

first scanning means for supplying to the first display area a first scanning signal for simultaneously scanning at least two scanning lines during one scanning line period; and

second scanning means for supplying to the second display area a second scanning signal for scanning at least one scanning line during one scanning line period, the second scanning signal having a selection period other than a selection period of the first scanning signal output from said first scanning means,

wherein said first scanning means supplies the first scanning signal to the first display area in the first field, and supplies a third scanning signal thereto in the second field, the third scanning signal having a selection period of at least one scanning line other than the selection period of the first scanning signal.

14. A liquid crystal display device for displaying an image of one frame formed of a first field and a second field, the display device comprising:

a liquid crystal display panel including a plurality of scanning lines and a plurality of segment lines formed in a matrix, and having a first display area and a second display area;

display data supply means for supplying a segment drive signal corresponding to display data to the segment lines of said liquid crystal display panel;

first scanning means for supplying to the first display area a first scanning signal for simultaneously scanning at least two scanning lines during one scanning line period; and

second scanning means for supplying to the second display area a second scanning signal for scanning at least one scanning line during one scanning line period, the second scanning signal having a selection period other than a selection period of the first scanning signal output from said first scanning means,

wherein said second scanning means supplies the second scanning signal to the second display area in the first field and supplies a further scanning signal thereto in the second field, the further scanning signal having a selection period of at least one horizontal scanning line other than the selection period of the second scanning signal.

15. A liquid crystal display device for displaying an image of one frame formed of a first field and a second field, the display device comprising:

a liquid crystal display panel including a plurality of scanning lines and a plurality of segment lines formed in a matrix, and having a first display area and a second display area;

display data supply means for supplying a segment drive signal corresponding to display data to the segment lines of said liquid crystal display panel;

first scanning means for supplying to the first display area a first scanning signal for simultaneously scanning at least two scanning lines during one scanning line period; and

second scanning means for supplying to the second display area a second scanning signal for scanning at least one scanning line during one scanning line period, the second scanning signal having a selection period other than a selection period of the first scanning signal output from said first scanning means,

wherein said second scanning means comprises odd-numbered line scanning means for scanning odd-numbered scanning lines of the second display area and even-numbered line scanning means for scanning even-numbered scanning lines of the second display area, said odd-numbered line scanning means supplies the second scanning signal to the odd-numbered scanning lines of the second display area, and said even-numbered line scanning means supplies a further scanning signal to the even-numbered scanning lines of the second display area, the further scanning signal having a selection period of at least one scanning line other than the selection period of the second scanning signal.

16. The device according to claim 15, wherein said odd-numbered line scanning means outputs the second scanning signal in the first field and the further scanning signal in the second field, and said even-numbered line scanning means outputs the further scanning signal in the first field and the second scanning signal in the second field.

17. A liquid crystal display device for displaying an image of one frame formed of a first field and a second field, the display device comprising:

a liquid crystal display panel including a plurality of scanning lines and a plurality of segment lines formed in a matrix, and having a first display area and a second display area;

display data supply means for supplying a segment drive signal corresponding to display data to the segment lines of said liquid crystal display panel;

first scanning means for supplying to the first display area a first scanning signal for simultaneously scanning at least two scanning lines during one scanning line period; and

second scanning means for supplying to the second display area a second scanning signal for scanning at least one scanning line during one scanning line period, the second scanning signal having a selection period other than a selection period of the first scanning signal output from said first scanning means,

wherein said first scanning means supplies another scanning signal having a selection period of three scanning lines in the first and second fields, said second scanning means comprises odd-numbered line scanning means for scanning odd-numbered scanning lines of the second display area and even-numbered line scanning means for scanning even-numbered scanning lines of the second display area, said odd-numbered line scanning means supplies the second scanning signal to the odd-numbered scanning lines of the second display area, and said even-numbered line scanning means supplies a further scanning signal to the even-numbered scanning lines of the second display area, the further scanning signal having a selection period of at least one scanning line other than the selection period of the second scanning signal.

18. The device according to claim 17, wherein the odd-numbered line scanning means of said second scanning means outputs the second scanning signal in the first field and the further scanning signal in the second field, and the even-numbered line scanning means of said second scanning means outputs the further scanning signal in the first field and the second scanning signal in the second field.