JP3390239B2 - Driving method of plasma display panel - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a plasma display panel which achieves low power consumption while maintaining the number of gradations. 2. Description of the Related Art In a plasma display panel, a pair of discharge electrodes (cathode and anode) are regularly arranged between two glass plates in which a rare gas mainly composed of neon is sealed. This is a display panel utilizing a discharge light emission phenomenon (negative glow, positive column) generated by applying a voltage to the formed minute discharge cells. [0003] Such a plasma display panel is roughly classified into a DC type and an AC type in terms of operation. Furthermore, the display function and the driving method are classified into a refresh method, a memory method, a self-scan method, and the like. [0004] When color display is performed with such a plasma display panel, it becomes necessary to add a function of gradation display. As a method of performing such a gradation display, for example, as shown in FIG. 1, it is known to divide one frame for displaying one screen into a plurality of subfields and control the light emission time of each subfield. Have been. FIG. 1 shows a case in which display of 2 ⁸ = 256 gradations is performed. One frame period is divided into eight subfields (first to eighth subfields), and the weight is heavy (light emission time is long). By lengthening the time of the (long) subfield and distributing the long time, the number of times of light emission is increased, the ratio of the light emitting time is increased, and a gray scale display with high luminance is enabled. Here, the time lengths of the first to eighth subfields are set to a ratio of 6: 3: 2: 1: 1: 1: 1: 1, respectively. The light emission period between the excitation pulse and the erase pulse in each subfield is T,
T / 2, T / 4, T / 8, T / 16, T / 32, T / 6
4, T / 128. [0008] As described above, gradation display is performed. In a color display plasma display panel, display light is obtained by applying ultraviolet light generated by plasma to a phosphor. In this process, the luminous efficiency decreases. Increasing the power to compensate for this will shorten the life and increase power consumption. Therefore, by utilizing the fact that there is no visual problem even if the luminance at the peripheral portion of the screen is slightly lower than that at the central portion, it is possible to reduce the power consumption by reducing the amplitude of the video signal at the peripheral portion of the screen. It is conceivable, however, that the number of gradations at the peripheral portion of the screen is reduced. That is, for example, 2
This is because if the light amount at the peripheral portion of the screen of the 56-gradation display panel is set to 50%, the portion can display only 128 gradations. The present invention has been made in view of such circumstances, and has as its object to provide a method of driving a plasma display panel capable of reducing power consumption while maintaining the number of gradations. . In order to achieve the above object, the present invention provides a method for driving a plasma display panel which divides one frame into a plurality of subfields and performs gradation display by modulating the number of times of light emission. In each subfield
From the center of the screen to the top of the screen
Or gradually decrease as approaching one or both of the lower ends
It is characterized in that it is made to be. In the method of driving a plasma display panel according to the present invention , one of the upper and lower ends of the screen of each subfield which does not cause a visual problem even if the luminance is slightly reduced.
Or, for both, gradually increase the number of line emission from the center of the screen.
By reducing the number of times, driving with low power consumption can be performed in a state where the original number of gradations is pseudo-maintained. Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows a driving apparatus according to an embodiment of the driving method of the plasma display panel of the present invention. As shown in FIG. 1, the A / D converter 1 converts an input composite video signal into, for example, 8-bit pixel data and sends it to the frame memory 3. The timing pulse generator 5 generates various timing pulses based on the horizontal and vertical sync signals extracted from the input composite video signal by the sync separator 4. When the memory control circuit 6 supplies a write pulse and a read pulse synchronized with the timing pulse from the timing pulse generation circuit 5 to the frame memory 3, the frame memory 3 receives the write pulse from the A / D converter 1 based on the write pulse. , And sends out the acquired pixel data to the output processing circuit 7 based on the readout pulse. The output processing circuit 7 is a first mode in which only the most significant bit of each pixel data is transmitted in synchronization with the timing pulse from the write / read pulse generation circuit 2, only the (most significant -1) digit bit Is transmitted to the address electrode driver 8 for each field in the pixel data transmission mode of the eighth mode in which only the least significant bit is transmitted. The write / erase control circuit 9 supplies a drive signal for writing or erasing in synchronization with the timing pulse from the write / read pulse generation circuit 2 to the first sustain electrode driver 10 and the second sustain electrode driver. Output to the electrode driver 11. FIG. 3 shows the address electrode driver 8,
First sustain electrode driver 10 and second sustain electrode driver 1
3 shows a voltage waveform applied to each electrode from No. 1.
That is, FIG. 7A shows a data pulse applied from the address electrode driver 8 to the column electrodes A1 to AJ. FIG. 5B shows the state of the common row electrode Y from the second sustain electrode driver 11.
3 shows sustain pulses of negative polarity applied to 1 to YK. FIGS. 3C, 3D and 3E show the first and the first.
The scan electrodes X1, X2,.
A sustain pulse of negative polarity applied to X2 and X3 is shown. Here, a scan pulse for starting light emission in response to the data pulse and an erasing pulse having a short pulse width for stopping light emission are applied to each sustain pulse. FIG. 2F shows the first row electrodes X 1 and Y 1.
Is a signal waveform indicating the discharge light emission state of the pixel at the intersection of the column electrodes A1 to AJ. The light emission is started by application of the data pulse and the scan pulse, the discharge light emission is repeatedly performed by the sustain pulse, and the light emission is performed by the erase pulse. Indicates that it will be stopped. FIG. 4 shows a method of driving a plasma display according to the present invention. In FIG. 4, 2 ⁸ = 25
This shows a case where six gradation display is performed, in which one frame for displaying one screen is divided into eight subfields of first to eighth. Pixels on each scanning line can display 256 gradations by selecting light emission in each subfield. Then, in each subfield, the number of times of light emission (in other words, light emission time) for the scanning line (line) at the center of the screen decreases so as to approach the upper end (one line) or the lower end (k lines) of the screen. The position (timing at which the erase pulse is applied) is controlled. That is, each scan line near the center of the screen in each subfield is written by application of a data pulse and a scan pulse, starts discharge light emission, and emits light in accordance with the weight (for example, the heaviest weight). 128 × 4 times, 64 × 4 times, 32 ×
4 times, 16 × 4 times, 8 × 4 times, 4 × 4 times, 2 × 4 times, 1
(E.g., 4 times) discharge light emission is repeated by a sustain pulse, and emission is stopped by application of an erase pulse. The number of light emission of the scan line of each subfield decreases as approaching the top or bottom of the screen. In the line at the upper end (first line) or the lower end (k-th line) of the screen of each subfield, for example, 128 × 2 times, 64 × 2 times,
32 × 2 times, 16 × 2 times, 8 × 2 times, 4 × 2 times, 2 × 2
The timing at which the erase pulse is applied is controlled according to the scanning line (row) so that the number of times becomes 1 × 2. FIG. 4 shows a configuration in which the number of times of light emission of each scanning line in each subfield is continuously reduced from the scanning line at the center of the screen to the scanning line at the upper or lower end. May be done. Further, the application of the above-mentioned erasing pulse depends on the writing / writing.
In the erase control circuit 9, the operation is performed at a timing corresponding to the scanning line (row). Although the above embodiment shows a case of 256 gradation display, the present invention can be applied to other gradation display values other than 256. As described above, according to the driving method of the plasma display panel of the present invention, the upper or lower edge of the screen of each subfield which does not cause a visual problem even if the luminance is slightly lowered. Line for one or both of
By gradually decreasing the number of times of light emission from the center of the screen , low power consumption driving can be performed in a state where the original number of gradations is maintained in a pseudo manner.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining a driving method for performing gradation display in a conventional plasma display panel. FIG. 2 is a diagram showing a driving device of a plasma display panel to which the present invention can be applied. FIG. 3 is a diagram showing a pulse waveform applied to each electrode of the driving device of FIG. 2; FIG. 4 is a diagram for explaining a method of driving a plasma display panel according to the present invention. [Description of Signs] 1 A / D converter 3 Frame memory 4 Synchronization separation circuit 5 Timing pulse generation circuit 6 Memory control circuit 7 Output processing circuit 8 Address electrode driver 9 Write / erase control circuit 10 First sustain electrode driver 11 2 sustain electrode driver

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G09G 3/28 G09G 3/20 611 G09G 3/20 641 G09G 3/20 642 H04N 5/66 101

Claims (1)

(57) [Claim 1] In a method of driving a plasma display panel that divides one frame into a plurality of subfields and performs gradation display by modulation of the number of times of light emission, the number of times of light emission of a line in each subfield On the screen
From the center to the top or bottom of the screen, or both
Therefore, a method for driving a plasma display panel, characterized in that the plasma display panel is gradually reduced .