JP2002006794A - Display device - Google Patents

Abstract

(57) [Problem] To provide a digital display device such as a plasma display with contrast adjustment without degrading gradation. SOLUTION: In a digital device such as a plasma display which adaptively controls light emission by controlling a driving circuit according to an APL of an input signal, an input signal AP
An APL detection circuit 1 for detecting an L signal and an input / output characteristic control circuit 2 for converting an input / output characteristic in response to the APL signal are provided, and the number of driving pulses corresponding to the input signal and the number of subfields are adaptively controlled. Fine contrast adjustment can be performed without reducing the amount of digitized data (without degrading gradation).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a display device using a digital display device such as a plasma display (hereinafter referred to as PDP), and more particularly to a display device capable of adjusting the number of subfields by brightness.

[0002]

2. Description of the Related Art Light emission control (contrast adjustment) of a conventional digital display device will be briefly described.

[0003] In recent years, digital signal processing of video signals has become common. In the course of signal processing, for example, an input signal is converted from an analog signal to a digital signal (hereinafter, referred to as A / D conversion), and a digital signal is converted to an analog signal. To (below,
D / A conversion).

A cathode ray tube (hereinafter, referred to as CRT) represented by a conventional display device is an analog display device, and the light emission luminance of the device is proportional to the electron dose used for light emission. As shown in FIG. 5, the flow of signal processing in the analog display device is as follows: after being converted into a digital signal by the A / D converter 11, various signal processing is performed by the signal processing circuit 7, and then the analog signal is converted by the D / A converter 12. After re-conversion to a signal, the gain adjustment circuit 13
The gain of each B is adjusted, and a desired image is displayed on the CRT. In this case, it is common for an analog display device to adjust contrast using a signal after D / A conversion.

Next, a digital display device typified by a PDP or a liquid crystal is driven by a digital method, and the light emission luminance of the device is proportional to the number of discharges in a certain time. A case where a bit and a number of sub-fields are uniquely associated with each other in a PDP as an example of a digital display device in 8-bit 256 gradation emission luminance expression will be described with reference to FIGS.

[0006] As shown in FIG. 3, consider a PDP of pixels arranged in 10 rows and 4 columns. It is assumed that the brightness of each of R, G, and B of each pixel is expressed by 8 bits, and that brightness of 256 gradations can be expressed (the number of bits and the number of gradations are not specified). The following description is for a G signal unless otherwise specified, and the same description applies to R and B.

In FIG. 3, an area A indicated by A has a signal level of 128 brightness. If this is expressed in binary, each pixel in the portion indicated by A is (1000 000
0) level signal is added. Similarly, the portion indicated by B has a brightness of 127, and a signal level of (0111 1111) is applied to each pixel. The portion indicated by C has a brightness of 125, and a signal level of (0111 1110) is applied to each pixel.
The portion indicated by D has a brightness of 125, and each pixel has
The signal level of (0111 1101) is added. The portion indicated by E has a brightness of 0, and a signal level of (0000 0000) is applied to each pixel. An 8-bit signal of each pixel is vertically arranged at the position of each pixel, and a horizontal slice of each bit is referred to as a subfield. That is, a method of dividing one field into a plurality of binary images having different weights and displaying them in a temporally overlapping manner is called a subfield method. In an image display method using the subfield method, one divided binary image is displayed. The image is called a subfield.

Since each pixel is represented by 8 bits, eight subfields can be obtained as shown in FIG.
By collecting the least significant bits of the 8-bit signal of each pixel, 10 ×
4 are referred to as a subfield SF1 (FIG. 2). The second bit from the least significant bit is collected and similarly arranged in a matrix to form a subfield S
F2. Thus, the subfield SF1,
SF2, SF3, SF4, SF5, SF6, SF7, S
Make F8. Needless to say, the subfield SF8 is obtained by collecting and arranging the upper bits.

FIG. 4 shows a standard type of PDP drive signal for one field. As shown in FIG. 4, the standard type of the PDP drive signal includes eight subfields SF1, SF2, S
It has F3, SF4, SF5, SF6, SF7, and SF8. Subfields SF1 to SF8 are processed in order, and all processing is performed within one field period.

The processing of each subfield will be described with reference to FIG. The processing of each subfield includes a setup organization P1, a writing period P2, and a maintenance period P3.
It consists of. In the setup period P1, a single pulse is applied to the sustain electrode, and only the operation electrodes (up to the operation electrode 4 in FIG. 4 are shown in FIG. 4 because only four scan lines are shown in the example of FIG. 3). , And there are actually a large number, for example, 480 lines). Thereby, a preliminary discharge is performed.

In the writing period P2, the scanning electrodes in the horizontal direction are sequentially scanned, and a predetermined writing is performed only on the pixels that have received the pulse from the data electrode. For example, when the subfield SF1 is being processed, the pixel indicated by “1” in the subfield SF1 shown in FIG. 2 is written, and the pixel indicated by “0” is
Writing is not performed.

In the sustain period P3, a sustain pulse (drive pulse) corresponding to a value weighted for each subfield is output. The written pixel indicated by “1” is subjected to plasma discharge for each sustain pulse, and a predetermined pixel brightness can be obtained by one plasma discharge. In the subfield SF1, the weight is “1”, so that “1” level brightness is obtained. In subfield SF2, the weight is “2”, so “2”
Level of brightness is obtained. That is, the writing period P2 is a period for selecting a pixel that emits light, and the sustaining period P3
Is a period during which light emission is performed the number of times corresponding to the weighting.

As shown in FIG. 4, subfield SF
1, SF2, SF3, SF4, SF5, SF6, SF
7, SF8 are 1, 2, 4, 8, 16, 32,
64 and 128 are weighted. Therefore, the brightness level for each pixel is 256 from 0 to 255.
It can be adjusted in stages.

In the area B shown in FIG.
Light emission is performed in SF2, SF3, SF4, SF5, SF6, and SF7, and no light emission is performed in the subfield SF8. Therefore, "127" (= 1 + 2 + 4 + 8
+ 16 + 32 + 64).

In the area A of FIG. 3, the subfields SF1, SF2, SF3, SF4, SF5, SF6, S
Light emission is not performed in F7, and light emission is performed in the subfield SF8. Therefore, a level of "128" brightness is obtained.

In the above-described subfield method in the case of 8-bit, 8-bit, 256-gradation light emission of the PDP, adjustment is made according to the brightness of the screen in order to provide an optimal screen display in a bright or dark scene. There is a need.

A display device capable of adjusting the brightness of a PDP is disclosed in Japanese Patent Application Laid-Open No. Hei 8-286636, but here, a sufficient adjustment is performed only by adjusting the number of times of light emission and gain according to the brightness. I can't do things.

The digital display device that performs light emission control by the above operation mainly has a configuration as shown in FIG. 6 or FIG. 7, and in FIG. In the case of FIG. 7, the contrast is adjusted by adjusting the gain of the input signal by the gain adjustment circuit 13 provided before the A / D converter 11.

[0019]

However, the method of adjusting the contrast by adjusting the gain of the input signal to the A / D converter 11 as described above tends to reduce the dynamic range of the A / D converter. However, the image quality is largely deteriorated because of the gradation reduction direction. One example will be described with reference to FIG.

The input signal shown in FIG. 8 is a signal whose luminance monotonically increases in the horizontal direction, such as a ramp waveform, and its input level is such that the amplitude of the video portion is 0.7 Vpp. Such a signal is input to the gain adjustment circuit 13 and the A / D converter 1
In the case of a configuration in which the gain is adjusted to 1 and output, for example, A
When the / D converter is a converter capable of expressing 8 bits (256 gradations) and its dynamic range is 1 Vpp, the input / output relationship of the A / D is such that the input potential is “A / D reference potential”. 0 output, input potential is "reference potential + 0.5V"
In the case of, 128 outputs and input potential is “reference potential + 1.0 V”
In this case, 255 outputs are obtained. That is, the A / D converter 1
A method of adjusting the contrast by adjusting the gain of the input signal to 1 is, for example, when the contrast is halved,
The luminance change having a maximum of 255 gradations is reduced to 128 gradations.

A method of digitally adjusting the contrast of the signal after A / D conversion will be described with reference to FIG. 9. If the amplitude of the input signal is 1 Vpp and the dynamic range of the A / D converter 11 is large. In the case of 1 Vpp,
The output of the A / D converter 11 is input to the signal processing circuit 7 as a 256 gradation output (8 bits full). In the conventional contrast adjustment in the digital processing system, the A / D
The input / output characteristic of the signal processing circuit 7 is controlled by multiplying the output of the converter 11 by a predetermined coefficient. In this method, as shown in FIG. 1 "is multiplied to obtain 256 outputs for 256 inputs.

When using with a contrast of 50%,
The coefficient of “0.5” is multiplied and 128 for 256 inputs.
, And the adjustment is in the same direction as the gradation reduction.

Therefore, when the contrast of the digital display device is adjusted by the conventional method to lower the contrast, it is equivalent to lowering the gradation, and the deterioration of the image quality due to the deterioration of the gradation is inevitable. In this case, the gradation is inferior to that of an analog device that directly displays an input signal without using an A / D converter.

In a digital device such as a PDP or a liquid crystal, a method of adjusting the contrast by adjusting the number of discharges or PWM may be considered. (The number of times is physically limited), and a sufficient adjustment range cannot be obtained in consideration of a general contrast adjustment range. Furthermore, in the method of simply increasing or decreasing the number of times of light emission, the power consumption is increased in proportion to the number of times of light emission, and there is a problem that it is difficult to reduce the power consumption. It is not possible to secure a large amount of change).

[0025]

In order to solve the above-mentioned problems, according to the present invention, the brightness of the whole image is amplified by a constant multiplication factor A to express light and dark, and the total number of gradations is k.
A video signal expressing the brightness of each pixel expressed by any of the gray scales in Z bits is obtained. Only the first bit in the Z bits is collected from the entire image, and 0s and 1s are arranged. The first
1 subfield, and only the second bit is collected from the entire screen to form a second subfield in which 0s and 1s are arranged. A field is configured, weighting is performed on each subfield, and drive pulses of N times the number of times of this weight or drive pulses of a time width of N times are output, and the number of all the drive pulses or the total number of the drive pulses of each pixel is output. The brightness is adjusted according to the period of the drive pulse, and the average level of the brightness of the input image (L
av), and the total number of gradations K based on an average level (Lav) of the brightness of the input image.
And the image feature determining means for determining the number of subfields Z and weighting and multiple N of weighting, or the number of subfields Z and multiple N of weighting, and multiplying the weight of each subfield by N based on the multiple N In a display device provided with weight setting means, the image feature determination means includes a Lav input / output characteristic control circuit, and receives the output thereof without changing the total number of gradations K and changing the number of subfields Z and weighting and multiples of weighting. N, or an adaptive brightness control circuit that adaptively determines the number of subfields Z and the multiple N of weights, and externally controls the Lav input / output characteristic control circuit to change the input / output characteristics of the device and adjust the contrast. Is performed.

According to the present invention, a video display capable of adjusting the contrast without reducing the gradation of the digital data (gradation) after A / D conversion or the digital input data, that is, without deteriorating the image quality. Equipment can be obtained.

[0027]

According to the first aspect of the present invention, the brightness of the whole image is amplified by a constant magnification A to amplify a video signal to express light and dark, and the total number of gradations is k. A video signal that expresses the brightness of each pixel expressed by any one of the gray levels in Z bits is obtained by collecting only the first bit in the Z bits from the entire image, , And only the second bit is collected from the entire screen to form a second subfield in which 0s and 1s are separated from each other. A sub-field is formed, weighting is performed on each sub-field, N times the number of driving pulses of the weighting, or N-times driving pulse is output, and the number of all driving pulses in each pixel or Adjust the brightness according to the period of all drive pulses, and An average level detecting means for detecting an average level of brightness (Lav); and a number of subfields Z, weighting and weighting without changing the total number of gradations K based on the average level of brightness (Lav) of the input image. A display device comprising: an image feature determining means for determining a multiple N or a subfield number Z and a multiple N of weighting; and a weight setting means for multiplying the weight of each subfield by N based on the multiple N. The determination means is provided with a Lav input / output characteristic control circuit, and receives the output thereof without changing the total number of gradations K without changing the number of subfields Z and weighting and multiple N of weighting, or the number of subfields Z
And an adaptive brightness control circuit that adaptively determines a multiple N of weights, wherein the contrast can be adjusted without changing the total number of gradations K by externally controlling the Lav input / output characteristic control circuit. This has the effect that the contrast can be adjusted by changing the drive characteristics without reducing data (gradation) after AD conversion or digital input data.

Next, in the invention according to a second aspect of the present invention, the Lav input / output characteristic control circuit is configured such that the Lav input / output characteristic control circuit uses
This is characterized by being a combined output circuit of the av lower limit value and the Lav input / output characteristic curve, and has the effect of changing the drive characteristics by setting the Lav lower limit value to adjust the contrast.

Next, the invention according to claim 3 of the present invention is characterized in that the Lav input / output characteristic control circuit is a circuit for adjusting the slope of the Lav input / output characteristic curve. By controlling the slope of the characteristic curve, the driving characteristic can be changed to adjust the contrast.

Next, the invention according to claim 5 of the present invention is characterized in that the Lav input / output characteristic control circuit is a Lav input / output characteristic curve shift circuit. Has the effect of changing the driving characteristics to adjust the contrast.

Next, according to a fifth aspect of the present invention, an average level (L) of brightness of an input image according to the first aspect is provided.
av), the image feature determining means for determining the number of subfields Z and weighting and multiples N of weighting, or the number of subfields Z and multiples of weighting N without changing the total number of gradations K, An output from an edge detection circuit that detects horizontal or vertical edges and their intensities is received, and the number of subfields Z and weighting and multiples N of weighting are obtained without changing the total number of gradations K from the Lav and edge intensity of the input image. Alternatively, the number of subfields Z and the multiple N of weights are determined to prevent cracking of the display device display unit due to an input image,
It has the effect that the display unit is not destroyed even if any image is displayed.

Next, according to a sixth aspect of the present invention, an average level (L) of brightness of an input image according to the first aspect is provided.
av), the image feature determining means for determining the number of subfields Z and weighting and multiples N of weighting, or the number of subfields Z and multiples of weighting N without changing the total number of gradations K, comprises: By providing a characteristic control circuit and linearly setting the relationship between display luminance and Lav, the number of subfields Z and weighting and multiple N of weighting, or the number of subfields Z and multiples of weighting without changing the total number of gradations K N is determined, and the power consumption of the display device is made constant regardless of the average brightness level (Lav) of the input image. Has the function of keeping.

(Embodiment 1) An embodiment of the invention described in the present invention will be described below with reference to the drawings.

In FIG. 10, an input signal is converted from analog to digital by an A / D converter 11 and is input to a Lav detection circuit 1 and a signal processing circuit 7 for detecting an average level (Lav) of image brightness. The output from the Lav detection circuit 1 is input to the input / output special control circuit 2, and the input / output characteristic control circuit 2 receives the signal from the Lav detection circuit 1 and outputs the number of subfields corresponding to the average level (Lav) of the input image. , Subfield weighting, etc., in the first drive circuit 8,
Output to the second drive circuit 9. First drive circuit 8, second drive circuit
Of the signal processing circuit 7 according to the driving method set by the control signal from the input / output characteristic control circuit 2.
Is reproduced on the display device 10.

The combination of the number of subfields determined by the control signal from the input / output characteristic control circuit 2 and the weighting of the subfields will be described in more detail below. By setting the number of subfields, the arrangement of subfields, the weighting of subfields, and the arrangement of pulses in subfields, which are used to display the image even with the same average brightness level (Lav), It is possible to freely set the output luminance for the input signal.

That is, taking an example in which attention is paid to a certain pixel, in order to express the brightness of the "32" level,
Even in the setting as shown in FIG. 11A, that is, in the setting of arranging 16 pulses in each of the first subfield (SF1) and the third subfield (SF3) among the four subfields (SF), the luminance is adjusted by the contrast adjustment. Is increased by a small amount, a setting can be used in which the pulses are evenly arranged in the four subfields as shown in FIG. In the case of this example, the number of pulses for the “32” level is the same, but the luminance is changed because the arrangement of the pulses is different. The factors of the luminance change in this example are due to the afterglow characteristics of the phosphor and the luminance sensitivity of the naked eye, and are examples in which the luminance changes due to the operation (arrangement / interval) of the non-light portion. By combining such an example and a method of simply increasing the number of times of light emission, multi-gradation of luminance change is realized.

A feature of the present invention is that the setting method changes the output luminance corresponding to the input signal level during the contrast adjustment, but does not change the luminance relative relationship between the pixels. Adjusting the setting items), and changing only the output luminance without changing the number of gradations K, that is, the number of subfields, the arrangement of subfields, the weighting of subfields, and the arrangement of pulses in subfields. By setting the total number of pulses in a fixed period and the pulse arrangement position, the output luminance with respect to the input signal level can be varied to realize a configuration capable of securing a sufficient variable range as a contrast adjustment function. .

(Embodiment 2) Next, one embodiment of claims 2 to 4 will be described.

The input / output characteristic control circuit 2 according to claim 2 is
This is realized by the configuration shown in FIG. The synthesis output circuit 3 calculates an average level (Lav) signal by synthesizing the average brightness level (Lav) and a lower limit instruction signal input from the outside, and outputs the average level (Lav) signal to the drive pulse number control circuit 4. The drive pulse number control circuit 4 receives the average level (Lav) signal and outputs the number of subfields corresponding to the average level (Lav) and the result of determining the weight of the subfield. With this configuration, the number of subfields and the weighting of the subfields can be varied by externally controlling the lower limit.

FIG. 12B shows an average level (Lav) input / output relationship. An average level (Lav) value equal to or lower than the value set by the lower limit is clipped to the lower limit and output. That is, assuming that the weighted output has a variable range of 0 to 255 steps, if the lower limit is not set, if the average level (Lav) value is 0, the weighted output of 255 is made. Is set to about 30%, the weighting increases only up to 178 levels, so that the weighting can be varied by varying the lower limit.

When this method is used, the amount of change in the average luminance of the entire input / output becomes minute, but when the contrast is adjusted, the signal whose weight is set low is low because the average level (Lav) is high. In contrast adjustment, there is a problem that an invariable region where the contrast does not change until the lower limit value becomes equal to or higher than the average level (Lav) occurs. For example, when a signal having the maximum average level (Lav) is input, the contrast is apparently not changed at all even if the lower limit value is changed by external control because the control and the last are already in the minimum state as operation restrictions.

The input / output characteristic control circuit 2 according to claim 3 is
This is realized by the configuration shown in FIG.

The APL slope adjusting circuit 5 adjusts the slope of the input / output characteristic curve by inputting a predetermined slope as shown in FIG. 13A, so that even if the signal has a low average level (Lav), the signal has a high average level. (Lav) signal is output. The drive pulse number control circuit 4 determines the number of subfields corresponding to the average level (Lav) signal, and
The result of subfield weight determination is output. With such a configuration, the number of subfields and the weighting of the subfields can be varied by externally controlling the slope of the input / output characteristics. When this method is used, there is a problem that the luminance of the entire average level (Lav) region is reduced as input / output characteristics.

The input / output characteristic control circuit 2 according to claim 4 is
This is realized by the configuration shown in FIG.

FIG. 14A is a diagram showing an internal circuit configuration of the input / output characteristic control circuit 2. Average level (La
v) The input / output characteristic curve shift circuit 6 shifts the input / output characteristic curve as shown in FIG. 14 (b) by inputting a predetermined shift amount, so that a low average level (Lav) signal has a high average level. (Lav) signal is output. The driving pulse number control circuit 4 outputs the average level (L
av) The number of subfields corresponding to the signal and the result of determining the weight of the subfield are output.

With this configuration, the number of subfields and the weighting of the subfields can be varied by externally controlling the shift amount of the input / output characteristics. When this method is used, there is a problem that the luminance of the entire average level (Lav) region is significantly reduced as input / output characteristics, and the power consumption of the set is unnecessarily reduced.

A display device according to a fifth aspect is a display device having the circuit configuration according to the first to fourth aspects,
As in the example shown in FIG. 15, the input signal is a pixel-by-pixel value,
Alternatively, a storage element 15 that stores the average value of a certain area
And an edge detection circuit 16 for detecting a difference between each pixel or a predetermined area in the horizontal direction and the vertical direction, thereby detecting a temperature difference of the panel caused by the difference, and when the temperature difference is equal to or more than a certain value. The number of subfields and the weight of the subfields are reduced by externally controlling the circuit according to claim 1 to 4, that is, the temperature difference generated due to the difference is reduced, and the panel is controlled by the temperature difference. It is possible to realize a configuration for preventing the panel from breaking and breaking.

A display device according to a sixth aspect is a display device having the circuit configuration according to any one of the first to fourth aspects, wherein the number of the subfields and the weighting of the subfields are externally controlled, as shown in FIG. As shown in the figure, it is possible to realize a configuration that keeps the set power consumption above a certain average level (Lav) constant. (In the related art, the input Lav and the power consumption are directly proportional, and the power consumption draws a minor increase curve.) With this configuration, the maximum power consumption of the entire set is fixed regardless of what video signal is input. As a result, the derating calculation of each element constituting the circuit becomes easy, and the effect of greatly reducing the efficiency of electric circuit design can be obtained.

[0049]

As described above, according to the present invention, A / D
A configuration for performing contrast adjustment after conversion or without reducing the gradation of a digital input signal can be realized. According to the fifth aspect, a configuration can be realized in which a display device is not destroyed no matter what input signal is displayed. According to the sixth aspect, the maximum power consumption of the set can be kept constant, no matter what input signal is displayed, the derating of the circuit components can be easily calculated, and the electric circuit design efficiency can be greatly reduced. Becomes possible.

[Brief description of the drawings]

FIG. 1 is an individual explanatory diagram of subfields SF1 to SF8.

FIG. 2 is an explanatory diagram of a state where subfields SF1 to SF8 overlap each other.

FIG. 3 is a waveform chart showing an example of a brightness distribution on a PDP screen.

FIG. 4 is a waveform chart showing a standard form of a PDP drive signal.

FIG. 5 is a schematic block diagram of signal processing in a conventional analog device.

FIG. 6 is a schematic block diagram of signal processing in a conventional digital device.

FIG. 7 is a schematic block diagram of signal processing in a conventional digital device.

FIG. 8 is an explanatory diagram of a case where contrast adjustment is performed by a conventional analog unit.

FIG. 9 is an explanatory diagram of a case where contrast is adjusted by a conventional digital unit.

FIG. 10 is a block diagram illustrating a configuration of a display device according to an embodiment of the present invention.

FIG. 11 is a diagram showing a luminance change principle when contrast is adjusted by the display device.

FIG. 12 is a block diagram and a characteristic diagram showing a configuration of a display device according to another embodiment of the present invention.

FIG. 13 is a block diagram and a characteristic diagram showing a configuration of a display device according to another embodiment of the present invention.

FIG. 14 is a block diagram and a characteristic diagram showing a configuration of a display device according to another embodiment of the present invention.

FIG. 15 is a block diagram showing a configuration of a display device according to another embodiment of the present invention.

FIG. 16 is an operation characteristic diagram of the display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lav detection circuit 2 Input / output characteristic control circuit 3 Synthetic output circuit 4 Drive pulse number control circuit 5 Lav input / output characteristic inclination adjustment circuit 6 Lav input / output characteristic shift circuit 7 Signal processing circuit 8 Drive circuit a 9 Drive circuit b 10 Digital display Device 11 A / D converter 12 D / A converter 13 Gain adjustment circuit 14 CRT 15 Storage element 16 Edge detection circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) DD26 EE29 FF09 JJ02 JJ04 JJ05

Claims (6)

[Claims] 1. A method for amplifying a video signal based on a constant magnification A to express the brightness of the whole image as light and dark, and the brightness of each pixel represented by any one of the total number of gradations k. Z
A video signal expressed in bits is obtained by collecting only the first bit out of the Z bits from the entire image, and
, And only the second bit is collected from the entire screen to form a second subfield in which 0s and 1s are separated from each other. A sub-field is formed, weighting is performed on each sub-field, N times the number of driving pulses of the weighting, or N-times driving pulse is output, and the number of all driving pulses in each pixel or The average level detecting means for adjusting the brightness according to the period of all the drive pulses and detecting the average level (Lav) of the brightness of the input image, and the total level based on the average level (Lav) of the brightness of the input image. Image feature determining means for determining the number of subfields Z and weighting and multiples of weighting N without changing the number of gradations K, or the number of subfields Z and multiples of weighting N;
In the display device having weight setting means for multiplying the weight of each subfield by N times based on the above, the image characteristic determining means includes an average level (Lav) input / output characteristic control circuit, An adaptive brightness control circuit that adaptively determines the number of subfields Z and weighting and multiples N of weighting without changing the number K, or the number of subfields Z and multiples of weighting N, wherein the average level (Lav) input / output A display device capable of adjusting contrast without changing the total number of gradations K by externally controlling a characteristic control circuit. 2. The average level (Lav) input / output characteristic control circuit is a composite output circuit of an average level (Lav) upper limit value and an average level (Lav) input / output characteristic curve according to a set value. The display device according to 1. 3. The display device according to claim 1, wherein the average level (Lav) input / output characteristic control circuit is a gradient adjustment circuit of an average level (Lav) input / output characteristic curve. 4. The display device according to claim 1, wherein the average level (Lav) input / output characteristic control circuit is an average level (Lav) input / output characteristic curve shift circuit. 5. The number of subfields Z and weighting and multiple N of weighting, or the number of subfields, without changing the total number of gradations K, based on the average brightness level (Lav) of the input image according to claim 1. Number Z and weighting multiple N
The image feature determination means for determining the horizontal and vertical edges of the input image and the output from the edge detection circuit for detecting the intensity thereof, without changing the total number of gradations K from the Lav and the edge intensity of the input image. Number of subfields Z and weighting and multiple N of weighting, or number of subfields Z
The display device according to claim 1, wherein a multiple N of the weighting is determined, and cracking of the display device display unit due to the input image can be prevented. 6. The number of subfields Z, weighting and multiple N of weighting, or the number of subfields without changing the total number of gradations K, based on the average brightness level (Lav) of the input image according to claim 1. Number Z and weighting multiple N
Is determined by providing a Lav input / output characteristic control circuit and linearly setting the relationship between display luminance and Lav, so that the number of subfields Z and weighting and multiples of weighting are maintained without changing the total number of gradations K. 2. The power consumption of the display device according to claim 1, wherein N or the number of subfields Z and the multiple N of the weights are determined, so that the power consumption of the display device can be kept constant regardless of the average brightness level (Lav) of the input image. Display device.