JPH1165521A - Drive system for plasma display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of gradations of a black side by providing the subfield of a sustaining period which is half of the least significant subfield, when a subfield whose maximum luminance is low and which does not emit a light is present. SOLUTION: Video signals of R, G, B is converted into a digital signal having the number of bits which are the number of subfields(SF) +1 in an A/D conversion part 1 to be written in a frame memory 2 and an SF-generating part 3 generates SF1-SF6 of one field and an SF0 being half the sustaining period of the SF1 by reading the digital signal. A peak level detecting part 6 detects the presence or absence of the data of the most significant bit. When the data are present. When data of the most significant bit are present, a PDP 5 is driven with data of the SF1-SF6 from the SF-generating part 3 by a drive part 4 via a drive sequence control part 7 and when data are not present, the PDP 5 is driven with data of the SF0-SF5 from the SF-generating part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display driving method, and more particularly to a method for increasing the number of gray levels on the black level side of a video signal.

[0002]

2. Description of the Related Art Plasma display panels (PDPs)
In such cases, since the drive voltage and the display output show non-linearity, it is not possible to display an image with the luminance gradation corresponding to the input signal, so the lighting period is subdivided and the number of times of lighting in each lighting period is controlled for each lighting period Then, a method of displaying gradation is used.
That is, as shown in FIG. 2, one field is composed of a plurality of subfields (SF) having different relative ratios of lighting times, and the video signal is converted into a digital signal having the number of bits corresponding to the number of subfields of one field. Then, the corresponding cell is lit in a required subfield (one subfield or a plurality of subfields) based on the bit data. Then, in each subfield, data for one screen is written to all cells in the address period, wall charges are formed in the cells to be lit, and a sustain pulse is applied to all cells in the subsequent sustain period to form the wall charges. In this case, the cell is discharged and turned on, thereby displaying an image having a required luminance gradation. Accordingly, the greater the number of subfields, the greater the number of luminance gradations, but is limited by the driving speed of the PDP. FIG. 2 shows an example in which the number of subfields is 6,
The human eye has a characteristic that is relatively sensitive to the gradation of a dark part of an image, and there is a problem that when displaying a natural image, insufficient gradation is noticeable in the dark part.

[0003]

In view of the above, the present invention adds a subfield whose sustain period is one half of the lowest subfield when the level of the video signal is less than the maximum luminance. An object of the present invention is to increase the gradation on the level side and eliminate the insufficient gradation in the dark part.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an apparatus for displaying a multi-gradation image by forming one field by a plurality of subfields having different relative ratios of luminance. Is converted into digital data of the number of bits obtained by adding 1 to the number of subfields of one field,
Subfields are generated by adding 1 to the number of subfields in one field. Excluding the least significant subfield when there is data of the most significant bit, excluding the most significant subfield when there is no data of the most significant bit And a display driving method for driving the display.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a display driving system according to the present invention, an A / D converter converts an image signal into digital data of the number of bits obtained by adding 1 to the number of subfields of one field, and performs A / D conversion. The recorded data is recorded in a frame memory, read out, and input to a subfield generation unit to generate one subfield by adding one to the number of subfields in one field. In the data from the A / D conversion unit, the most significant bit data is detected by the peak level detection unit. If there is data, the least significant subfield is excluded. If there is no most significant bit data, the most significant bit is removed. Except for the sub-field, the display is driven via the drive unit to display an image.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a display driving method according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a main part of an embodiment of a display driving method according to the present invention, and FIGS. 2 and 3 are explanatory diagrams of a driving sequence. In FIG. 1, reference numeral 1 denotes an A / D conversion unit which converts the red (R), green (G), and blue (B) video signals into the number of bits (for example, 7) obtained by adding 1 to the number of subfields (for example, 6). Bit) digital signal. Reference numeral 2 denotes a frame memory for recording digitally converted R, G, and B video signals for one frame. 3 is a subfield generator,
Based on the data of the first (least significant) bit read from the frame memory 2, the 0th subfield (SF0) is
First subfield (SF1) based on bit data
The sixth subfield (SF6) is generated based on the data of the seventh (most significant) bit. 4 is a drive unit,
PDP based on the signal from subfield generator 3
5 is driven. Reference numeral 6 denotes a peak level detection unit which is the most significant bit (MS) of data read from the frame memory
The presence (1) and absence (0) of the data of B) are detected. A drive sequence control unit 7 controls the subfield generation unit 3 and the drive unit 4 and switches the drive sequence based on a signal from the peak level detection unit 6.

Next, the operation of the display driving method according to the present invention will be described. As shown in FIG. 2, one field is composed of six subfields SF1 to SF6, and each subfield is composed of an address period and a sustain (lighting) period. In the subfield generating unit 3, the relative ratio of luminance is 1 (SF1): 2 (SF) based on the upper 6 bits of the 7-bit data read from the frame memory 2.
2): 4 (SF3): 8 (SF4): 16 (SF5): 32 (SF
6) is generated, and in addition, as shown in FIG. 3, a subfield (SF0) having a luminance relative ratio of 1/2 of the lowest subfield (SF1) is generated. In driving the PDP 5, an address voltage is applied to an address electrode of the PDP 5 based on display data during an address period of each subfield to form a wall charge in a corresponding cell (this wall charge is cleared before the next subfield). Then, a sustain pulse is applied to the sustain electrode during the subsequent sustain period, and a sustain discharge is performed in each cell from the first electrode to the second electrode, and then from the second electrode to the first electrode. The number of times of the sustain discharge is, for example, 4 cycles in SF1, 8 cycles in SF2, 16 cycles in SF3,.
In step 6, 128 cycles are performed, and the luminance gradation of the cell (pixel) is determined by which (one or more) of the subfields the sustain discharge is performed.

When the peak level detector 6 detects the presence of MSB data in the data from the frame memory 2, the drive sequence controller 7 controls the SF1, SF2,. The PDP 5 is driven by the driving unit 4 based on the data of
The PDP 5 displays an image including the maximum luminance gradation.
When the peak level detector 6 detects no MSB data, the drive sequence controller 7 controls the SF0
(Sustain discharge is 2 cycles) to drive sequence from SF5 to SF5 (SF6, ie, remove the uppermost subfield), whereby PDP5 increases the number of gray levels on the black level side and lacks gray levels in the dark part of the image. Is eliminated.

[0009]

As described above, according to the display driving method according to the present invention, when the level of the video signal is equal to or less than the maximum luminance, the subfield having the half of the lowest subfield in the sustain period is set. In addition, since the gray level on the black level side is increased, it is possible to eliminate the insufficient gray level in the dark part of the image that is visually conspicuous.

[Brief description of the drawings]

FIG. 1 is a main block diagram of an embodiment of a display driving method according to the present invention.

FIG. 2 is an explanatory diagram of an example of a drive sequence.

FIG. 3 is an explanatory diagram of switching of a drive sequence.

[Explanation of symbols]

 Reference Signs List 1 A / D conversion unit 2 Frame memory 3 Subfield generation unit 4 Drive unit 5 PDP 6 Peak level detection unit 7 Drive sequence control unit

Claims (3)

[Claims] 1. A multi-gradation video display system in which one field is composed of a plurality of sub-fields having different relative ratios of luminance, wherein a video signal is obtained by adding 1 to the number of sub-fields of one field. It is converted into digital data, and subfields are generated by adding 1 to the number of subfields in one field. If there is data of the most significant bit, the least significant subfield is excluded. If there is no data of the most significant bit, A display driving method that drives each display except for the top subfield. 2. The video signal is converted into digital data of the number of bits obtained by adding 1 to the number of subfields of one field, and each subfield is generated by bit data excluding the least significant bit. 2. The display driving method according to claim 1, wherein when there is no sustain period, the sustain period generates a sub-field that is one-half of the least significant sub-field to drive the display. 3. A multi-gradation video display system in which one field is composed of a plurality of sub-fields having different luminance relative ratios, wherein a video signal is obtained by adding 1 to the number of sub-fields of one field. An A / D converter for converting to digital data; a frame memory for recording data from the A / D converter; and a sub-field of the number obtained by adding 1 to the number of sub-fields of one field based on the data read from the frame memory. A sub-field generator for generating a field, a driver for driving a display based on a signal from the sub-field generator, and a peak level detector for detecting the most significant bit data from the data from the A / D converter When there is data of the most significant bit, the least significant subfield is excluded, and when there is no data of the most significant bit, the most significant subfield is excluded. A display drive system that drives each display except for the field.