JP3067138B2 - Driving method of matrix type display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to conventional television images (aspect ratio 4: 3) and wide aspect television images such as HDTV (aspect ratio 16: 9, 5: 3). , Etc.) for driving a matrix-type display device on the premise of display.

[Conventional technology]

Conventional televisions have a screen aspect ratio of 4: 3
It is assumed that In contrast, HDTV or ED
Next-generation televisions such as TVs require a horizontally long screen, for example, an aspect ratio of 16: 9. In the future, there will be no doubt that a receiver capable of displaying these plural types of television images will be required. Japanese Patent Laid-Open Publication No. Hei.
194574, 1-1194575 and 1-194576.
There is a video display device using a CRT (cathode ray tube). For the structure and driving method of the matrix type display device, see the document “Commercialized liquid crystal pocket color television” (Koguchi et al., Nikkei Electronics, 1984.9.1
0) on pages 233 to 236. However, at present, an effective proposal has not yet been made for a receiver that displays a plurality of television images having different aspect ratios using a matrix display device.

[Problems to be solved by the invention]

The present invention has been made in view of the above circumstances,
Its purpose is to provide an appropriate method for processing the margins that occur when displaying conventional (4: 3 aspect ratio) television images on landscape (eg 16: 9 aspect ratio) screens. Another object of the present invention is to realize a method of driving a matrix type display device which can support television images of a plurality of different systems.

[Means for solving the problem]

A method for driving a matrix display device according to the present invention includes a plurality of column lines, a plurality of row lines, and picture elements connected to the plurality of column lines and row lines, and having different aspect ratios. In the driving method of the matrix type display device for switching and displaying an image, when the first image having an aspect ratio of about 4: 3 is displayed, the first scanning is performed during an effective scanning period of the video signal of the first image and outside the effective scanning period. When a video signal is supplied to the column line and a second video having an aspect ratio larger than the first video is displayed, the video signal is supplied to the column line only during an effective scanning period of the video signal of the second video. When the first video signal is supplied and the first video signal is displayed, the pulse width of the row line selection pulse supplied to the row line and the time ratio of the video display period for displaying the first video are approximately 4: 3. It is characterized by becoming.

When displaying the first video, a signal of a predetermined gradation level is displayed on the picture element outside the effective scanning period.

〔Example〕

Conventional television signals (NTSC, PAL, etc.) are premised on displaying images on a display having an aspect ratio of 4: 3. On the other hand, a video signal of a next-generation television such as an HDTV (high-definition television) or an EDTV is formed on the assumption that the video signal is displayed on a display which is longer in the horizontal direction (for example, an aspect ratio of 16: 9). Hereinafter, the conventional mode of displaying images with an aspect ratio of 4: 3 is referred to as “4: 3 display mode”, and the mode of displaying images with an aspect ratio wider than 4: 3 (for example, 16: 9). This is called "wide display mode".

FIG. 1 is a diagram for explaining the above two display modes using a matrix type display device. In FIG. 1, a matrix type display device 1 includes a plurality of column lines (4) connected to a column driver 2, a plurality of row lines (5) connected to a row driver 3, and the column lines and the rows. It comprises picture elements (6, 7, 8) formed at the intersections with the lines. Here, the column driver 2 includes a shift register 12. The aspect ratio of the screen of the matrix type display device 1 is 16: 9 (horizontally long), which corresponds to a wide display mode such as HDTV. When displaying an image on the matrix type display device 1 in the 4: 3 display mode, margins 10 and 11 are provided at an arbitrary ratio on the left and right sides of the image display unit 9, and an image of a predetermined gradation level (for example, (Solid image) is displayed.

FIG. 2 is a diagram for explaining a driving method in the wide display mode. In the figure, V1, SP1, and CK1 are signals supplied to the column driver 2, and are video signals (V
1), a scan start signal (SP1) for the shift register 12, and a scan clock (CK1) for the shift register 12. Also, L10,
L11 and L12 represent row line selection pulses supplied to the row lines from the row driver 3, for example, L10 is the Nth row line, L11 is the (N + 1) th row line, and L12 is the (N + 2) th row line. This is a row line selection pulse for driving. V1 in the figure is HD
TV video signal, P1 is the horizontal blanking period, P2
Represents an effective scanning period (a period during which a display signal is present).
Actually, in order to perform overscan, the video signal in the period P3 of the effective display period P2 is displayed on the matrix display device. The display period P3 is determined by the scan start signal SP1 and the scan clock CK1 supplied to the shift register 12 included in the column driver 2. Focusing on a certain row line, if there are a total of M picture elements on this row line, the first picture element has a time of T1, the second picture element has a time of T2, The time of T3 for the third picture element, ...
The video signal is captured at the time of TM. The above operation is repeated every time all the row lines are selected. The pulse width of the row line selection pulse, that is, the row line selection period P4 includes the display period P3, and the selection periods of the adjacent row line selection pulses L10, L11, and L12 do not overlap. As described above, a normal image having a horizontally long state (for example, an aspect ratio of 16: 9) can be obtained in the wide display mode.

FIG. 3 is a diagram for explaining a driving method in the 4: 3 display mode. In the figure, V2 is a video signal of a conventional television. V3, SP2, and CK2 are signals supplied to the column driver 2, and are a video signal (V3), a scan start signal (SP2) of the shift register 12, and a scan clock (CK2) of the shift register 12, respectively. L20, L21, L22 are
Each represents a row line selection pulse supplied to the row line from the row driver 3. For example, L20 is an Nth row line, L21 is an (N + 1) th row line, and L22 is a row for driving an (N + 2) th row line. This is a line selection pulse. In the figure, a period P5 included in the video signal V2 represents a horizontal blanking period, and P6 represents an effective scanning period (a period during which a display signal exists). Actually, the video signal of the predetermined period P7 included in the effective scanning period P6 is displayed on the matrix display device. The difference from the above-described wide display mode is that a signal representing a predetermined gradation level A is provided before and after the video display period P7 by a predetermined margin portion period P8, P9.
Form a video signal V3 formed by inserting, column driver (2)
Is to supply this V3. Therefore, the total display period P10 in the 4: 3 display mode is equal to the video display period P.
7 and display period P8 and P9 of the predetermined gradation level signal in the margin
Consisting of Note that the gray level of the margin may be B different from A. The display period P10 is a scan start signal SP2.
And the scanning clock CK2. Focusing on a certain row line, if there are a total of M picture elements on this row line, the first picture element has a time of T21, the second picture element has a time of T22, The video signal V3 is captured at the time T2i for the i-th picture element and at the time T2M for the M-th picture element. The above operation is repeated every time all the row lines are selected.
The pulse width of the row line selection pulse, that is, the row line selection period P11 includes the display period P10, and the adjacent row line selection pulses L20, L21, L22
Selection periods do not overlap. In this manner, a normal image can be obtained in the 4: 3 display mode.

By the way, in the case of the NTSC signal, the following relational expression holds. ("NHK Color Television Textbook [1]" (Nippon Broadcasting Publishing Association) P.9) (P5 + P6) x 0.83 = P6 (1) Conventionally, overscan of about 10% is usually performed. To establish.

P7 ≒ 0.9 × P6 (2) From (1) and (2) P7 ≒ (P5 + P6) × 0.75 (3) Therefore, in the present invention, the pulse width P11 of the row line selection pulse is
Is determined to be equal to (P5 + P6). At this time, the video display period P7 is approximately 75% of P11.

〔The invention's effect〕

By adopting the driving method of the present invention described above, a video signal based on a landscape screen such as HDTV or EDTV as a next-generation television system and a screen having an aspect ratio of 4: 3 as a conventional system are assumed. A matrix display device capable of receiving and displaying both video signals is realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a matrix type display device and explaining an image display section and a blank section. FIG. 2 is a diagram for explaining a driving method in a wide display mode according to the present invention. FIG. 3 is a diagram for explaining a driving method in the 4: 3 display mode of the present invention.

Continuation of the front page (56) References JP-A-1-268272 (JP, A) JP-A-2-1433781 (JP, A) JP-A-2-244880 (JP, A) JP-A-2-137585 (JP) JP-A-1-194574 (JP, A) JP-A-64-15795 (JP, A) NHK Television Technical Textbook (1), edited by The Japan Broadcasting Corporation, April 1989. Japan Broadcasting Publishing Association. p9 (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/46 H04N 5/66-5/74 H04N 7/01 G09F 9/00 G09G 3/00-3/36

Claims (2)

(57) [Claims] 1. A matrix which has a plurality of column lines, a plurality of row lines, and picture elements connected to the plurality of column lines and row lines, and switches and displays images having different aspect ratios. In the method of driving a display device, when a first image having an aspect ratio of about 4: 3 is displayed, an image signal is applied to the column line during an effective scanning period of the image signal of the first image and outside the effective scanning period. Supplying a video signal to the column line only during an effective scanning period of the video signal of the second video when displaying a second video having an aspect ratio larger than the first video; When displaying a video signal, a pulse width of a row line selection pulse supplied to the row line and a time ratio of a video display period for displaying the first video are approximately 4: 3. A method for driving a matrix display device. 2. The matrix type display according to claim 1, wherein when said first video is displayed, a signal of a predetermined gradation level is displayed on said picture element outside said effective scanning period. A method for driving a display device.