JP2001175220A - Gradation display processor for plasma display panel and its processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise color temperature and also to adjust brightness without decreasing display gradation in a PDP(plasma display panel). SOLUTION: In this processor, one field period is divided into subfields SF2 to SF8 having respective numbers of gradation and, also, an offset SF is provided and an input signal (a) is converted into digital data having 256 gradation and the processor performs assigning intensity levels of the PDP according to the number of gradation of the subfield adapted for the number of gradation of the input signal among respective subfields SF1 to SF8 and, also, when the APL(average picture level) of the blue signal in the input signal exceeds a prescribed value, the device perform luminous control equivalent to a time corresponding to its excess value in the offset subfield. Moreover, the processor detect levels of red, green and blue signals in the input signal to control increase or decrease of light emitting times in the offset SF period in accordance with magnitude of these detected levels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradation display processing apparatus for a plasma display panel used for displaying an image on a television or an advertisement display board, and a processing method therefor.

[0002]

2. Description of the Related Art Plasma display panels (hereinafter referred to as P
In DP), a brightness control method of performing gradation display for image display includes, as shown in FIG. 5, a plurality of display brightnesses weighted in one field period (predetermined light emission period) of 1/60 second. Subfield SF1, SF2, SF3
.., A method of providing SF8 is used. Each subfield is divided into a writing period for writing discharge of display data, a sustaining period for display discharge, and an erasing period for terminating the sustaining discharge. In the example of FIG. 5, eight subfields SF1, SF
2, SF3,..., SF8 are provided in one field. The length of the period of each subfield differs according to the weighting of the luminance.

For example, each subfield SF1, SF
2, SF3, ···, respectively luminance in emission at _{^{SF8, 2 0 × B 0 (}} B 0 = standard _{^{brightness), 2 1 × B 0,}} 2 2
× B ₀ ,..., 2 ⁷ × B ₀ , the light emission time (sustain period) in each subfield SF1, SF2, SF3,. 4 for SF4, 8 for SF5, 16 for S
In F6, it is 32, in SF7 it is 64, and in SF8 it is 128, and a display of 2 ⁸ = 256 gradations is performed by a combination of these light emission.

[0004] Such luminance control is realized by a drive circuit shown in FIG. In FIG. 4, the PDP unit 10
0 is for AC type adaptation, and PDP 1001 has M
.., DM, and the data electrodes D1, D2, D3,.
Scan electrodes SC1, SC2, SC3 forming a pair in each of the rows
..., SCN and sustain electrodes SU1, SU2, SU3
.., SUN are arranged in a matrix. Further, the PDP unit 100 has data electrodes D of M columns.
, D2, D3,..., DM, and the scan electrodes SC1, SC2, SC3,.
.., SCN and sustain electrodes SU1, SU2, SU3,.
Scan / maintain / erase driver 10 for driving SUN
3 are provided.

[0005] Further, as a driving unit for driving the PDP unit 100, as shown in FIG.
D conversion unit 12, γ correction unit 13B, frame memory 14,
An output processing unit 15, a synchronization separation unit 16, a timing pulse generation unit 17, a memory control unit 18, and a drive timing generation unit 19 are provided.

Next, the flow of a signal for driving PDP unit 100 will be briefly described. The magnitude of the input signal a, which is an input video signal, is adjusted by the level adjustment unit 11 and output to the 8-bit A / D conversion unit 12. A / D converter 12
Converts the level of the input signal a adjusted by the level adjustment unit 11 into 8-bit data and outputs the 8-bit data to the γ correction unit 13B.

In the γ correction unit 13B, the emission luminance of each of the signals (R: Red), green (G: Green), and blue (B: Blue) constituting the digital video data from the A / D conversion unit 12 is linear. Then, the red (R), green (G), and blue (B) signal data corrected by performing the γ correction so as to change to the frame memory 14 are sent to the frame memory 14. These video data are temporarily stored in the frame memory 14, and the output processing unit 15 converts the data read from the frame memory 14 into P
The data is sent to the data driver 102 in the DP unit 100 to drive the data driver 102. On the other hand, the synchronizing separation unit 16 generates a timing pulse
And the timing pulse generator 17 generates a timing pulse. This timing pulse generator 17
A / D converter 12 is controlled by the output of
The memory controller 18 and the drive timing generator 19 are controlled.

[0008] Then, the scanning / sustaining / erasing driver 103 in the PDP unit 100 is driven by the timing output of the driving timing generator 19 to display the PDP 101. The output of the drive timing generator 19 is fed back to the memory controller 18. The memory controller 18 includes a timing pulse generator 17 and a drive timing generator 1
9 in synchronism with each output, and controls the writing of data to the frame memory 14 and the reading of data from the frame memory 13, whereby the frame memory 14
Is sent to the data driver 102 in the PDP unit 100 via the output processing unit 14 and the data driver 1
02 is driven.

Next, the level adjustment of the input signal a will be described. FIG. 6 shows a time change diagram of an input signal of a general TV (television) display. The input signal a is roughly divided into
There are an input signal of an average signal level, a maximum input signal of a level B that frequently appears, and a peak input signal of a level A that occasionally appears. Now, A / D conversion is performed by the level adjustment unit 11 shown in FIG.
The signal level output to the converter 12 is the level A in FIG.
When adjusted to (Peak input), level A (Peak input)
All the signals up to are converted into digital signals by the A / D converter 12. Therefore, as shown in FIG. 7, 256 gradations can be displayed for all input signals up to the peak luminance corresponding to the peak input. That is, the change in the input signal shown in FIG. 6 is displayed on the PDP 101 as a change in luminance as shown in FIG.

[0010]

Generally, in a PDP, the luminous efficiencies of red (R), green (G), and blue (B) signals constituting an input video signal are not uniform. For this reason, the color temperature at the time of displaying a white signal is considerably lower at 6,000 degrees than 11,000 degrees realized by a CRT.

[0011] Such red (R), green (G), blue (B)
When the luminous efficiency of each signal is corrected by the PDP device using an electric signal, the red (R), green (G), red (G), and green (G) signals are output by the level adjuster 11 disposed in front of the A / D converter 12 shown in FIG. The adjustment of the voltage level according to each blue (B) signal is performed. In this case, when the voltage of the bright blue (B) signal is adjusted to, for example, a voltage level corresponding to the maximum output value “256” (that is, 256 gradations) of the A / D converter 12, the brightness is reduced to red ( The voltage levels of the R) and green (G) signals are output values of “130” to “15” of the A / D converter 12.
0 ", and as a result, PD
There is a problem that the number of display colors is considerably reduced to about 5.4 million colors in a PDP in which the color temperature is adjusted to the same level as that of a cathode-ray tube, compared to 16.77 million colors of the original display colors of P.

A brightness adjustment function, which is standardly provided in a television using a cathode ray tube, also has a brightness adjustment function by adjusting the DC voltage level in the PDP in the same manner as described above. , Only display with reduced gradation can be performed.

Accordingly, the present invention provides a PDP comprising:
An object of the present invention is to increase the color temperature without reducing the display gradation and adjust the brightness.

[0014]

In order to solve such a problem, the present invention is directed to a plurality of sub-pixels provided within one field period indicating a predetermined light-emitting period and having light-emitting times each of which is weighted as a gradation number. A field, a PDP that performs display in accordance with the number of tones of the subfield, and a conversion unit that, when a video signal is input, converts the input video signal into a digital video signal having a predetermined number of tones. In a device for performing PDP gradation display based on the number of gradations of a digital video signal obtained, an offset subfield is provided within one field period, and a light emission time within the offset subfield period is set according to the level of an input video signal. It is characterized by providing a control unit for controlling the amount. In this case, a detection unit for detecting the average video level of the blue signal in the input video signal is provided, and when the level value detected by the detection unit exceeds a predetermined level, the light emission proportional to the excess level value is provided. It is displayed in the amount of time. In addition, a detection unit for detecting the level of each of the red, green, and blue signals constituting the input video signal is provided, and the control unit includes:
The amount of light emission time is controlled according to the detection level value detected by the detection unit. Further, the control section decreases the emission time amount when the detection level value detected by the detection section is higher than the specified level, and increases the emission time amount when the detection level value is lower than the specified level.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a PDP device to which the present invention is applied. A PDP unit 100 constituting the present device includes M columns of data electrodes D1,.
And scan electrodes SC1,..., S forming a pair in each of N rows.
.., SUN in a matrix, a data driver 102 for driving the M-column data electrodes, and a scan / sustain for driving the N-row scan electrodes / sustain electrodes. .Erase driver 10
3 is an AC-adaptive PDP unit.

The PDP device includes a PDP unit 1
00 as a driving unit for driving the A / 00
D conversion unit 12, γ conversion unit 13A, frame memory 14,
Output processing unit 15, synchronization separation unit 16, timing pulse generation unit 17, memory control unit 18, drive timing generation unit 1
9, an APL detection unit 20 and an offset control unit 21 are provided.

Next, referring to FIG.
Will be briefly described. The magnitude of the input signal a, which is an input video signal, is adjusted by the level adjustment unit 11 and output to the 8-bit A / D conversion unit 12. A
The / D converter 12 converts the level of the input signal a adjusted by the level adjuster 11 into 8-bit data, and
Output to 3A.

In the γ converter 13B, the red (R: Re) constituting the digital video data output from the A / D converter 12 is
d), green (G: Green) and blue (B: Blue) are subjected to γ conversion so that the emission luminance of each signal changes linearly, and the converted red (R), green (G), and blue ( Each signal data of B) is sent to the frame memory 14. These video data are temporarily stored in the frame memory 14, and the output processing unit 15 sends the data read from the frame memory 14 to the data driver 102 in the PDP unit 100 to drive the data driver 102. Data is output to the data electrodes D1,..., DM. On the other hand, the synchronization separator 16 drives the timing pulse generator 17 based on the input signal a, and causes the timing pulse generator 17 to generate a timing pulse. The output of the timing pulse generator 17 allows the A / D converter 1
2 is controlled, and the memory controller 18 and the drive timing generator 19 are controlled.

The scan / sustain / erase driver 103 in the PDP unit 100 is driven by the timing output of the drive timing generator 19, whereby the scan electrodes SC1,..., SCN and the sustain electrodes SU1,.
The scan pulse and the sustain pulse are output to the SUN, respectively, and the display of the video data is performed on the PDP 101. The output of the drive timing generator 19 is output from the memory controller 1
8 is returned. The memory controller 18 operates in synchronization with the outputs of the timing pulse generator 17 and the drive timing generator 19 to control writing of data to the frame memory 14 and reading of data from the frame memory 13. As a result, data is sent from the frame memory 14 to the data driver 102 in the PDP unit 100 via the output processing unit 14 to drive the data driver 102, and the PDP unit is driven by the timing output of the drive timing generation unit 19 as described above. 10
0, the scan / maintain / erase driver 103 is driven, and P
Video data is displayed on the DP 101.

The APL detector 20 shown in FIG. 1 converts the red (R), green (G), and blue (B) converted by the gamma converter 13A.
Of the predetermined signal data (in this example, blue (B) signal data), the average video level (APL: Ave)
(A.Picture Level), and when the average video level of the blue (B) signal data detected by the APL detection unit 20 becomes equal to or higher than a predetermined level,
The offset control unit 21 shown in FIG. 1 controls the output processing unit 15 to output the data of the frame memory 14 to the data driver 102 during the offset subfield period described later, and controls the drive timing generation unit 19 to change the blue ( B) The entire surface of the signal is emitted.

That is, in the present embodiment, as shown in FIG. 2, the writing period for the writing discharge of the display data and the display period in one field period (predetermined light emitting period), which is 1/60 second, respectively. It has a sustaining period for discharging and an erasing period for ending the sustaining discharge, and each light emitting time (sustaining period) corresponds to the number of gradations 1, 2, 4, 8,
Eight subfields SF1, SF2, SF3, SF4, SF weighted as 16, 32, 64, 128
5, SF6, SF7 and SF8 are provided, and the above-described offset subfield SF is added to the subfield SF8. Then, at all times, a subfield corresponding to the gradation number of the data converted by the A / D conversion unit 12 and corrected by the γ conversion unit 13A is selected, and the light emission of the PDP 101 is controlled according to the gradation number of the selected subfield. When the average video level of the blue (B) signal data detected by the APL detection unit 20 becomes a predetermined value or more, in addition to the light emission control based on the number of gradations of the subfields SF1 to SF8, the offset subfield SF period Then, light emission control for a time proportional to the detection level value is performed.

The light emission during the offset subfield SF causes the blue (B) signal to be emitted simultaneously on the entire screen of the PDP 101. The offset control unit 21 determines that the average video level of the blue (B) signal is equal to or higher than a predetermined level. If
By outputting the blue (B) signal data stored in the frame memory 14 to the data electrode D and controlling the output timing of the drive timing generation unit 19, the number in proportion to the average video level value of the blue (b) signal is controlled. From the scanning / sustaining / erasing driver 103,
The voltage is applied to scan electrode SC and sustain electrode SU.

That is, when the average video level of the blue (B) signal detected by the APL detection unit 20 is, for example, 40% or less of the maximum average level as shown in FIG. 3, the light emission control is performed during the offset subfield SF. However, if the level detected by the APL detection unit 20 exceeds a predetermined level of 40%, the excess level value is changed from the time point of the offset subfield SF period (start time point of the offset subfield SF) shown in FIG. The scanning / sustaining / erasing driver 103 generates a proportional number of light emission pulses, and applies the same to each of the scan electrodes SC1 to SCN and each of the sustain electrodes SU1 to SUN as a scan pulse and a sustain pulse. B) Increasing the light emission level of the signal. Thus, the color temperature can be increased without reducing the display gradation of the PDP 101.

In the offset subfield SF period, the entire screen of the PDP 101 is simultaneously turned on. Therefore, during the writing period from the offset subfield SF shown in FIG. 2, the blue (B) data of the frame memory 14 is not changed. After being output to the data driver 102 and applied to the data electrode D, the output timing of the drive timing generation unit 19 is controlled by the offset control unit 21, and the scan / sustain / erase driver 103 outputs the signal to each scan electrode S.
Scan pulses are simultaneously applied to C1, SC2, SC3,..., SCN. Thereby, the writing period is 1
The writing period can be shortened because the period for the line is sufficient and the application of the scanning pulse for each scanning electrode becomes unnecessary.

On the other hand, when the emission control based on the detection of the average video level of the blue (B) signal is not performed during the offset subfield SF, all of the red (R), green (G), and blue (B) are used. Light emission control for the color signal is performed. This light emission control includes red (R), green (G), and blue (B)
The number of light emission pulses is controlled for all of the color signals, so that the brightness can be adjusted without reducing the display gradation. That is, in addition to the light emission control based on the number of gradations of the subfields SF1 to SF8, the APL detection unit 20 detects the average video level for all red (R), green (G), and blue (B) color signals. The offset control unit 21 controls the number of light emission pulses in accordance with the detection level value during the offset subfield SF, so that the PDP 10
1. The brightness of the screen is adjusted.

The brightness adjustment is performed by an ABL (Auto Beam L) which is a standard equipment of a CRT television.
It is also possible to apply to an (imiter) function. That is, in addition to the light emission control based on the number of gradations of the subfields SF1 to SF8, the APL detection unit 20 detects the average video level for all red (R), green (G), and blue (B) color signals. If the detection level is lower than the specified level and the pattern is dark, the offset control unit 21 controls the increase of the number of light emission pulses during the offset sub-field SF to brighten the screen of the PDP 101 and the APL detection unit. In the case of a bright pattern whose detection level is higher than the specified level, the offset subfield S
The present invention can be applied to the above-described ABL function in which the screen of the PDP 101 is darkened by controlling the number of light emission pulses to be reduced in the F period.

[0027]

As described above, according to the present invention, a plurality of subfields provided within one field period indicating a predetermined light emission period and each of which has a light emission time weighted as a gradation number, and A PDP for performing display in accordance with the number of gradations, and a conversion unit for converting the input video signal into a digital video signal having a predetermined number of gradations when a video signal is input. In an apparatus that performs PDP gradation display based on a tone, an offset subfield is provided within one field period, and the amount of light emission time in the offset subfield period is controlled according to the level of an input video signal. So P
Brightness (Brig) without reducing the display gradation of DP
htness) adjustment can be performed, and when the level of the blue (B) signal in the input video signal rises above a certain level, for example, the light emission time in the offset subfield period is increased. The color temperature can be increased without reducing the display gradation. In addition, a detection unit that detects an average video level of a blue signal in the input video signal is provided, and when a level value detected by the detection unit exceeds a predetermined level, a display is performed with a light emission time amount proportional to the excess level value. Thus, the color temperature can be raised accurately without reducing the display gradation of the PDP. Also, a detection unit for detecting the levels of the red, green, and blue signals constituting the input video signal is provided, and the amount of light emission time is controlled according to the detection level value detected by the detection unit. The brightness can be adjusted accurately without reducing the display gradation. In addition, when the detection level value detected by the detection unit is higher than the specified level, the light emission time amount is reduced, and when the detection level value is lower than the specified level, the light emission time amount is increased. ABL (Auto Beam) that brightens the screen when the image is bright and darkens the screen when the pattern is bright
m Limiter) function.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a PDP device to which the present invention has been applied.

FIG. 2 is a diagram showing the timing of gradation display in the PDP device.

FIG. 3 is a diagram showing a relationship between an input signal level and a display level in an offset field period in the PDP device.

FIG. 4 is a block diagram of a conventional PDP device.

FIG. 5 is a diagram showing the timing of gradation display of a conventional PDP device.

FIG. 6 is a diagram showing the state of an input signal in a conventional PDP device.

FIG. 7 shows an input signal and a PDP in a conventional PDP device.
FIG. 6 is a diagram showing a relationship between the output signal and the output signal.

FIG. 8 is a diagram showing a state of a display input signal to a conventional PDP.

[Explanation of symbols]

11: Level adjustment unit, 12: A / D conversion unit, 13A: γ
Conversion unit, 14: frame memory, 15: output processing unit, 1
6: Synchronization separation unit, 17: Timing pulse generation unit, 18
... Memory control unit, 19 ... Drive timing generation unit, 20 ...
APL detection unit, 21 offset control unit, 100 plasma display unit, 101 plasma display panel (PDP), 102 data driver, 10
3: Scan / maintain / erase driver, D1 to DM: data electrode, SC1 to SCN: scan electrode, SU1 to SU9: sustain electrode, SF1 to SF8: subfield, SF: offset subfield, a: input signal (input image) signal).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/288 G09G 3/28 EB

Claims (8)

[Claims] When a video signal is input, a plurality of subfields provided in one field period indicating a predetermined light emission period, each of which has a light emission time weighted as a gradation number, a plasma display panel, and an input video signal To a digital video signal having a predetermined number of gradations, and selecting a subfield corresponding to the number of gradations of the digital video signal converted by the conversion unit, and selecting the gradation of the selected subfield. A gradation display processing apparatus for a plasma display panel for performing gradation display of said plasma display panel based on a number of pixels, wherein an offset subfield is provided within said one field period, and said offset is set according to a level of said input video signal. A control unit for controlling the amount of light emission time in the subfield period. Gradation display processing device of the plasma display panel. 2. The apparatus according to claim 1, further comprising a detection unit configured to detect an average video level of a blue signal in the input video signal, wherein the control unit determines that a level value detected by the detection unit exceeds a predetermined level. A gradation display processing apparatus for a plasma display panel, wherein the display is sometimes performed with an emission time amount proportional to the excess level value. 3. The apparatus according to claim 1, further comprising: a detection unit configured to detect a level of each of red, green, and blue signals included in the input video signal, wherein the control unit includes a detection level value detected by the detection unit. A gradation display processing apparatus for a plasma display panel, wherein the amount of light emission time is controlled according to the time. 4. The apparatus according to claim 1, further comprising: a detection unit that detects a level of each of red, green, and blue signals constituting the input video signal, wherein the control unit detects a detection level value detected by the detection unit. A gradation display processing apparatus for a plasma display panel, characterized in that, when is higher than a specified level, the amount of light emission time is reduced, and when the detected level value is lower than the specified level, the amount of light emission time is increased. 5. A plurality of subfields provided within one field period indicating a predetermined light emission period and each of which has a light emission time weighted as a gradation number, a plasma display panel, and a video signal, the input video signal To a digital video signal having a predetermined number of gradations, and selecting a subfield corresponding to the number of gradations of the digital video signal converted by the conversion unit, and selecting the gradation of the selected subfield. A gradation display processing apparatus for a plasma display panel that performs gradation display of the plasma display panel based on a number of the sub-fields, wherein an offset sub-field is added to the sub-field; A display step of controlling the amount of light emission time within the field period. Gradation display processing method of a plasma display panel according to symptoms. 6. The method according to claim 5, further comprising a detecting step of detecting an average video level of a blue signal in the input video signal, wherein the displaying step is performed such that a level value detected by the detecting step exceeds a predetermined level. A step of displaying a light emission time amount proportional to the excess level value at the time of the display. 7. The method according to claim 5, further comprising a detecting step of detecting a level of each of red, green, and blue signals constituting the input video signal, and wherein the displaying step includes a detecting level detected by the detecting step. Controlling the amount of light emission time according to the value. 8. The apparatus according to claim 5, further comprising a detecting step of detecting a level of each of red, green, and blue signals constituting the input video signal, and wherein the displaying step includes a detecting level detected by the detecting step. A step of reducing the amount of light emission time when the value is higher than a specified level, and increasing the amount of light emission time when the detected level value is lower than the specified level. .