JP3564951B2 - PDP display device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a PDP (plasma display panel) that performs gradation display by a subfield method and that increases a display gradation on a dark screen.
[0002]
[Prior art]
In a PDP that performs display by pulse discharge, in order to perform gradation display of a television image or the like, one field is divided into sub-fields corresponding to each bit of a digital video signal to be displayed, and bits corresponding to each of the sub-fields are divided into sub-fields. The pulse discharge is performed the number of times proportional to the weight. Increasing the number of subfields increases the number of display gradations. However, since there is a scanning period for display pixels in each subfield, display luminance decreases. Therefore, if the power consumption is fixed, the number of display gradations and the display luminance have a trade-off relationship in principle. Therefore, expressing an image whose screen brightness changes with time, such as a television, with sufficient luminance and fine display gradations is a difficult task due to the relationship with power saving. When sufficient luminance is obtained, there is a problem that insufficient gradation is particularly noticeable on a dark screen that is easily visually noticeable.
[0003]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a technique for resolving a lack of gradation on a dark screen that is visually conspicuous without changing power consumption or maximum display luminance.
[0004]
[Means for Solving the Problems]
Empty subfield detecting means for detecting the presence or absence of a signal corresponding to the subfield in one field of the video signal to be displayed; and sequence control means for controlling the driving sequence of the subfield in accordance with the presence or absence of the empty subfield. A half LSB sub-field is provided for weighting a half of a sub-field corresponding to an LSB (Least Significant Bit) of a video signal in a field having an empty sub-field . The display gradation is increased by displaying the 1/2 LSB subfield in the detected empty subfield .
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
In a PDP display device that performs gradation display of a video signal by a subfield method using a PDP (plasma display panel), detecting an empty subfield that detects the presence or absence of a signal corresponding to the subfield in one field of the video signal Means and sequence control means for controlling the drive sequence of said subfield in accordance with the presence or absence of an empty subfield, wherein a subfield having a smaller weight than a subfield corresponding to the LSB of the video signal in a field having an empty subfield is provided. To increase the display gradation.
[0006]
According to the subfield method, gradation display is performed in order from MSB (Most Significant Bit) to LSB in descending order of weight, and when the empty subfield is detected, the next subfeed is moved up and displayed. .
[0007]
The subfield having a weight smaller than the LSB is a 1/2 LSB subfield having a weight of 1/2 of the LSB subfield.
[0008]
In the gradation display by the subfield method, the 1 / 2LSB subfield is displayed in the detected empty subfield.
[0009]
The detection of the empty sub-feed is performed only in the sub-field corresponding to the MSB.
[0010]
The detection of the empty sub-feed is performed only in the MSB and the sub-field corresponding to the bit having the next largest weight.
[0011]
The detection of the empty field is performed by an FF circuit which sets each bit of the digital video signal to be displayed and resets it with a vertical synchronization signal.
[0012]
【Example】
FIG. 1 is a block diagram of a main part of an embodiment of a PDP display device according to the present invention. FIG. 2 is a timing chart of a subfield for gradation display of the display device. The input video signal S1 is converted into, for example, an 8-bit digital video signal by the A / D conversion circuit 1 and stored in the field memory 2 which can be read for each bit. The data is read out from the field memory 2 by the data selection circuit 4a at the timing of the scanning periods SF7s, SF6s,... Of the subfields SF7, SF6,. Wall charges are formed at each pixel at the intersection of the x and y matrix electrodes of the AC PDP 7 by the x and y matrix electrode drivers 6x and 6y of the PDP 7. Next, the lighting pulse number selection circuit 4b stores the data of the corresponding lighting pulse number from the ROM 8 in which the lighting pulse number proportional to the weight of each bit is stored in advance, in the lighting period SF7d of each of the subfields SF7, SF6,. SF6d,..., And the lighting drive circuit 5b applies discharge pulses of the number of lighting pulses between the y electrode and the common electrode 6c running in parallel with the y electrode, and is proportional to the weight of each bit. The emitted luminance is emitted. Thus, gradation display of the input video signal S1 is performed on the PDP 7.
[0013]
In the present invention, the upper 6 bits of the digital video signal are usually used, for example, and the subfields SF7 to SF2 are displayed within one field period in descending order of weight from the MSB to the LSB. By doing so, the period for each subfield can be lengthened, and since the scanning period is generally a fixed value determined by the number of y electrodes, the lighting period can be lengthened and the display luminance can be increased. An empty subfield is detected by the FF circuit 3 which is set for each bit of the digital video signal by data of each pixel of the same video signal and reset by the vertical synchronization signal S2. When an empty subfield is detected, the data selection circuit 4a and the lighting pulse number selection circuit skip that subfield and display the next subfield. In this manner, in this example, when there are two or more empty subfields between the subfields SF7 and SF2, it is possible to display substantially 256 gradations from SF7 to SF0 in that field. Become.
[0014]
When an empty subfield is detected, the subfield to be displayed is a subfield with a weight smaller than the LSB, that is, in the above case, a 1 / 2LSB subfield having a weight of 1/2 of SF2 which is a subfield of the LSB. The field may be SF1.
In this case, by displaying SF1, which is a 1/2 LSB subfield, in the detected empty subfield, it is necessary to arrange the subfields SF7 to SF2 in descending order of weight from the MSB toward the LSB. And can be lit in any order.
[0015]
The detection of a vacant sub-feed can be performed with all of the bits to be always displayed, for example, with all the 6 bits in the above example, but may be performed with only the sub-field corresponding to the MSB. In this case, one FF circuit 3 for detecting an empty sub-feed may be provided for each video signal, and it is sufficient if there are three FF circuits corresponding to three primary colors of RGB. In addition, the data selection circuit 4a and the lighting pulse selection circuit 4b are correspondingly simplified. In this way, when the display luminance is equal to or less than half of the maximum, a subfield equal to or less than LSB can be displayed. Further, in order to increase the circuit scale slightly so that subfields equal to or less than LSB can be displayed even when the display luminance is equal to or less than 3/4 of the maximum, the detection of empty subfeeds is performed by using the MSB and the next weighting. May be performed in a subfield corresponding to a bit having a larger value.
[0016]
【The invention's effect】
As described above, the empty subfield detecting means for detecting the presence or absence of a signal corresponding to the subfield in one field of the video signal to be displayed, and the driving sequence of the subfield corresponding to the presence or absence of the empty subfield. provided sequence control means for controlling, because that can be provided of subfield smaller weighting corresponding to the LSB of the image signal in unused sub field is present field, to increase the display gradation of a dark screen Can be
Therefore, in the normal screen it is high brightness display, in particular can fine gradation representation is visually conspicuous dark screen, a high-quality image can be displayed in the same power consumption.

[Brief description of the drawings]
FIG. 1 is a block diagram of a main part of an embodiment of a PDP display device according to the present invention.
FIG. 2 is a timing chart of a subfield for gradation display of the display device.
[Explanation of symbols]
Reference Signs List 1 A / D conversion circuit 2 Field memory 3 FF circuit 4a Data selection circuit 4b Lighting pulse number selection circuit 5a Scanning drive circuit 5b Lighting drive circuit 6x x driver 6y y driver 6c Common electrode 7 PDP
8 ROM
S1 input video signal S2 vertical synchronization signal SF7, SF6,.

Claims (2)

In a PDP (Plasma Display Panel) using a PDP (Plasma Display Panel), which performs gradation display using higher-order bits of a video signal using a subfield method, the presence or absence of a signal corresponding to the subfield in one field of the video signal And a sequence control means for controlling the driving sequence of the subfield in accordance with the presence or absence of the empty subfield. The LSB (Least Significant Bit) of the video signal in the field having the empty subfield is provided. And a half LSB subfield having a weight of 1/2 of the subfield corresponding to the subfield method, and the gradation display by the subfield method displays the 1 / 2LSB subfield in a detected empty subfield. PDP display device. In a PDP (Plasma Display Panel) using a PDP (Plasma Display Panel), which performs gradation display using higher-order bits of a video signal using a subfield method, the presence or absence of a signal corresponding to the subfield in one field of the video signal And a sequence control means for controlling the driving sequence of the subfield in accordance with the presence or absence of the empty subfield. The LSB (Least Significant Bit) of the video signal in the field having the empty subfield is provided. It is provided of subfield smaller weighting corresponding to the detection of the unused sub-fields, each set with each bit of the digital video signal to be displayed, the FF circuit and to Rukoto resetting the vertical synchronizing signal Characteristic PDP display device.

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