JPH07184218A - Picture display device - Google Patents

Abstract

PURPOSE:To keep uniformed picture quality and white balance and to cancel gamma correction with a small capacity ROM and an adder by adopting logarithmic transformation, addition and inverse logarithmic transformation for multiplication between a video signal and uniformed correction data. CONSTITUTION:A video signal is converted into a digital signal by an A/D converter 11, gamma correction for a cathode ray tube is cancelled by using a ROM table 12 and the result is subjected to logarithmic transformation. Furthermore, outputs of a unit correction data memory 13 and a line correction data memory 14 used for correction of uniformed picture quality are respectively subjected to logarithmic transformation by logarithmic transformation ROM tables 17, 18. Thus, the uniformizing correction of a picture is realized by adding the data by an adder 19 and applying inverse logarithmic transformation to the result. A ROM table 20 is used for nonlinear signal conversion to keep the white balance of a picture display element after applying inverse logarithmic transformation to an output of the adder 19. Since the ROM is provided separately for a video signal, unit correction and line correction, a small capacity of the ROMs is enough to realize the processing above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generates an electron beam for each division when a screen on a screen is divided into a plurality of divisions in the horizontal and vertical directions, and horizontally generates each electron beam for each division. And a device for displaying a plurality of beam spots on a screen by deflecting in the vertical direction and displaying an image as a whole.

[0002]

2. Description of the Related Art In recent years, various flattening devices for displaying television images have been proposed.

An image display device as a flat-type color picture tube of this type has hitherto been disclosed in, for example, Japanese Patent Application Laid-Open No. 57-135590.
It has a structure as shown in the publication. The configuration will be described below with reference to the drawings.

As shown in FIG. 4, this image display device has a back electrode 1, a line cathode 2 as an electron beam emission source, a beam extraction electrode 3, and a beam flow control in this order from the rear to the anode side. An electrode 4, a focusing electrode 5, a horizontal deflection electrode 6, a vertical deflection electrode 7, a screen plate 8 and the like are arranged and configured, and these are housed inside a vacuum container.

The operation of the flat type image display device constructed as described above will be described below.

As shown in FIG. 4, the line cathode 2 serving as an electron beam emission source is stretched in the horizontal direction so as to generate electron beams distributed in a line in the horizontal direction. Are further provided at regular intervals in the vertical direction (in FIG. 4, only 7 of 2a to 2t are shown). In this structure, the line cathodes are spaced at 4.4 mm, and the number of line cathodes is 19, and the number of line cathodes is 2 to 2. The distance between the line cathodes cannot be freely set to a large value, and is regulated by the distance between the vertical deflection electrode 7 and the screen plate 8 described later. As the structure of these wire cathodes 2, an oxide cathode material is applied to the surface of a tungsten rod having a diameter of 10 to 30 μm. As will be described later, the above-mentioned line cathode is controlled so as to sequentially emit an electron beam from the upper line cathode 2a to the lower two line cathodes at regular intervals.

The back electrode 1 suppresses the generation of electron beams from the line cathodes other than the corresponding line cathode, and at the same time, the electron beam is emitted.
It also has the function of pushing the mud only in the anodic direction. Figure 4
Although a vacuum container is not shown, it is possible to use the back electrode 1 to form a structure integrated with the vacuum container. Bee
The lead-out electrode 3 is a conductive plate 11 having a plurality of through-holes 10 arranged in a row at regular intervals in the horizontal direction facing each of the line cathodes 2a to 2 and an electron beam emitted from the line cathode 2. Through the through hole 10.

Next, the beam flow control electrode 4 is connected to the line cathodes 2a to 2b.
A plurality of vertically long conductive plates 15 each having a through hole 14 at a position facing each other are arranged side by side in a horizontal direction at a predetermined interval. 11 in this configuration
Four beam flow control electrode conductive plates 15a to 15n are provided (only eight are shown in FIG. 4). The beam flow control electrode 4 synchronizes the passing amount of each electron beam divided in the horizontal direction by the beam extraction electrode 3 with the picture element of the video signal and in synchronization with the horizontal deflection timing described later. Let me control. The video signal here is R,
The digital image signal is A / D converted for each of G and B colors, and the electron beam is irradiated for a time proportional to the digital image signal. Therefore, the passing amount of the electron beam is almost proportional to this digital video signal.

Normally, the video signal is modulated in consideration of the relationship between the electron beam amount and the brightness of an image display device using a cathode ray tube (hereinafter referred to as gamma correction). The relationship between the beam and the brightness is different from that of the image display device using the CRT, and a correction circuit described later is required.

The focusing electrode 5 is a conductive plate 17 having a through hole 16 at a position facing each through hole 14 provided in the beam flow control electrode 4, and focuses the electron beam.

The horizontal deflection electrode 6 is composed of a plurality of conductive plates 18 and 18 'vertically arranged along both sides of the through hole 16 in the horizontal direction. Voltage is applied. The electron beam for each picture element is deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen plate 8 to emit light. In this configuration, each electron beam is deflected by 2 trio.

The vertical deflection electrode 7 is composed of a plurality of conductive plates 19 and 19 'arranged in the horizontal direction at the respective intermediate positions in the vertical direction of the through holes 16, and a vertical deflection voltage is applied to the vertical deflection electrode 7 to generate an electronic beam. -The beam is deflected vertically. In this structure, the electron beam generated from one line cathode is vertically deflected by 12 lines by the pair of electrodes 19 and 19 '. The vertical deflection electrodes 7 composed of 20 pieces form 19 pairs of vertical deflection conductors corresponding to the 19 line cathodes, respectively, and 228 pieces of the vertical deflection conductors 228 are arranged on the surface of the screen plate 8 in the vertical direction. Drawing a horizontal scan line.

As described above, in this structure, the horizontal deflection electrodes 6 and the vertical deflection electrodes 7 are arranged in a plurality of comb shapes. Furthermore, by setting the distance to the screen plate 8 longer than the distance between the horizontal and vertical deflection electrodes, the electron beam can be moved with a small deflection amount.
It becomes possible to irradiate on the surface of. This makes it possible to reduce deflection distortion both horizontally and vertically.

As shown in FIG. 4, the screen plate 8 is formed by coating the back surface of the glass plate 21 with the phosphor 20 in a stripe shape. Although not shown, metal back and carbon are also applied. The phosphor 20 deflects the electron beam passing through one through hole 14 of the beam flow control electrode 4 in the horizontal direction so as to irradiate the phosphor pairs of three colors R, G and B for two trio. It is provided and is applied in stripes in the vertical direction. In FIG. 4, the screen
The broken lines on the panel 8 indicate vertical divisions displayed corresponding to the plurality of line cathodes 2, and the two-dot chain line is displayed corresponding to each of the plurality of beam flow control electrodes 4. Indicates the horizontal division. As shown in the enlarged view of FIG. 5, one section partitioned by a broken line and a two-dot chain line has two trio R, G, and B phosphors in the horizontal direction and a width of 12 lines in the vertical direction. ing. In this example, the size of one section is 1 mm in the horizontal direction and 4.4 mm in the vertical direction.

In FIG. 5, the phosphors of three colors R, G and B are shown in stripes, but they may be arranged in a delta shape. However, when they are arranged in a delta shape, it is necessary to apply horizontal deflection and vertical deflection waveform voltages suitable for them. Note that in FIG. 5, the vertical and horizontal dimensional ratios are different from the actual image displayed on the screen for convenience of explanation.

Further, in this configuration, one of the beam flow control electrodes 4 is
Two R, G, and B phosphors are provided for one through hole 14, but one trio or three or more trio may be used. However, the beam flow control electrode 4
In this case, R, G, B video signals of 1 trio or 3 trios or more are sequentially added, and horizontal deflection must be performed in synchronization with them.

As described above, the image display device used in the present invention includes a minute image display unit (1 m in the above example).
m.times.4 mm) are arranged vertically and horizontally and a single image is displayed as a whole. Therefore, if there is a variation in the flow rate of the electron beam that lights each pixel display unit, it is uniform as a whole. The image quality does not appear. Also,
If there are variations in the intervals between adjacent lines, if the intervals are larger than other parts, the areas are darker, and if the intervals are smaller, the areas are brighter, and uniform image quality is not obtained.

Furthermore, the relationship between the electron beam and the brightness of the image display device used in the present invention is non-linear, or R, G, B is used.
If the three colors have different relationships, even if the image quality is made uniform with a certain level of brightness and white balance adjustment is performed, the uniformity of the image quality and the white balance will be lost at other brightness levels. Further, although the normal video signal is gamma-corrected, the image display device used in the present invention is different from the image display device using the CRT in that the relationship between the electron beam and the brightness is different from that of the image display device using the CRT. You will not be able to reproduce the same image as the device.

In order to solve such a problem, the conventional image display device has an image signal correction circuit as shown in FIG. 6, for example. In FIG. 6, 51 to 53 are R,
An A / D converter for converting an analog image signal for each of G and B colors into a digital signal, 54 is a memory in which information of luminance distribution for each image display unit in the image display element is recorded, 55
Is an address generation circuit for controlling the memory 54, 56 is a memory in which information of the luminance distribution for each line of the image display element is recorded, 57 is an address generation circuit for controlling the memory 56, and 58 to 60 are video signals. Is a ROM table for converting the.

The brightness distribution information recorded in the memories 54 and 55 is obtained as follows. First,
A video signal having a certain size is input to the image display device. At this time, if the flow rates of the electron beams in the image display unit forming the image display element are completely the same and the intervals of the lines are completely equal, a uniform luminance distribution is obtained over the entire image display area. If there are variations in the flow rate of the electron beam in the unit, or if the intervals between the lines are not uniform, then there will be areas of uneven brightness. The brightness at this time is first measured for each image display unit, and the data corresponding to the negative of the brightness distribution of each unit (the bright part is small, the dark part is large) is recorded in the memory 54. Next, each line is divided into a plurality of parts in the vertical direction, the brightness is measured for each section of each line, and the data corresponding to the negative of the brightness distribution for each section of each line is recorded in the memory 56.

Further, the address generation circuits 55 and 57 are
The data of the memory 54 or 56 and the image display element are synchronized with each other by the horizontal synchronizing signal h and the vertical synchronizing signal v so as to always have a one-to-one correspondence.

Next, the ROM tables 58-60 will be described. These ROMs take into consideration cancellation of gamma correction, multiplication of data from the memories 54 and 56 by a video signal, and a relationship (R, G, B colors) between a video signal and brightness peculiar to the image display device. Conversion of the video signal (that is, the relationship between the video signal whose gamma correction has been canceled and the luminance must be proportional, so the video signal side is converted so as to have a proportional relationship). It is carried out.

A method of creating data in the ROM tables 58-60 will be described. First, the video signal is gamma-corrected by a factor of 2.2 to correct the relationship between the current and the brightness of the image display device using a cathode ray tube.
The gamma correction is canceled by converting the video signal to the power of 2.2 to the digital video signal.

Next, assuming that the image signal converted to the above power of 2.2 and the luminance of the screen have an exact proportional relationship, the screen equalization correction is realized by multiplying the signals from the memories 54 and 56 by the image signal. Explain what is done. In FIG. 7, it is assumed that when the video signal is a, the normal brightness of the screen is La, and when the brightness unevenness occurs, it becomes Lb. At this time, in order to make the brightness uniform at the point where the brightness non-uniformity occurs, it is necessary to correct the input at the normal point to b. At this time, since La / Lb = a / b = constant, the correction amount is constant regardless of the size of the video signal.
It suffices to simply perform a multiplication conversion in which the video signal is multiplied by a constant proportional to the magnitude of the signals from 4, 56.

In the above description, the relation between the video signal and the luminance is proportional to all the R, G and B3 primary colors. However, when this relation is non-linear for each color, the luminance correction will be performed if this relation is not taken into consideration. , The white balance cannot be achieved at the same time as it can be applied only in a part of the brightness range that can be taken. However, if a conversion for canceling the above-mentioned non-linear relation is applied to the video signal, the brightness uniformization correction becomes effective in the entire range of possible brightness, and the white balance can be maintained at the same time. That is, the above-mentioned non-linear relationship for each color is formulated, an inverse function thereof is obtained, and the video signal is converted based on this function.

The relationship between the A / D-converted video signal x and the outputs y of the ROM tables 58 to 60 is summarized by combining the above-mentioned three conversions.

[0027]

[Equation 1]

(Function f is a function including all of the above three conversions, that is, the inverse conversion of gamma correction, the multiplication with the signal from the memory, and the conversion in consideration of the luminance-dependent relationship between the video signal and the chrominance signal. Non-linear. Generally, the function f is different for each color.), And the data of the ROM tables 58 to 60 are created so that the conversion satisfying this expression can be performed.

In summary, the video signal after A / D conversion is
First, the inverse transformation of gamma correction is performed, and then the memories 54 and 5
6 is multiplied by the correction signal from the image display device 6, and is subjected to conversion in consideration of the color-specific emission characteristics of the image display device. These three processes are performed by the ROM tables 58-60.

[0030]

However, in the above-described conventional image signal correction circuit configuration, the inverse conversion of gamma correction, screen equalization correction, and non-linear correction of R, G, and B3 primary colors are all performed in the ROM table 58 to. I'm going to 60. The address requires at least 8 bits as a video signal, at least 4 bits for uniformization correction for each image display unit, and at least 5 bits for uniformization correction for each line. At least 8 bits are required as data.

Therefore, the ROM capacity is R, G,
B requires a large-scale memory of at least 1 Mbit each, which results in a large cost burden. Also, in terms of board mounting, the A / D converter and the ROM must be separately arranged for each of R, G, and B, which is large. It has a problem that it requires an area.

The present invention solves the above-mentioned problems of the prior art, is extremely advantageous in terms of cost, realizes space saving in terms of board mounting, and is as flexible as the structure using a ROM table. It is an object of the present invention to provide an image display device having such a correction circuit.

[0033]

In order to achieve the above object, the image display device of the present invention comprises an A / D conversion means for converting an image signal into a digital image signal, and each of the image display elements on the screen. First storage means in which the brightness nonuniformity of each unit section is recorded in advance, second storage means in which the brightness nonuniformity of a plurality of line sections of each scanning line of the image display element is recorded in advance, and the digital image First digital image signal converting means for performing inverse gamma correction and logarithmic conversion on the signal; second digital signal converting means for performing logarithmic conversion on the output signal of the first storage means; Thirdly performing logarithmic conversion on the output signal of the storage means of
Of the digital signal converting means, the adding means for adding the output of the first digital signal converting means, the output of the second digital signal converting means, and the output of the third digital signal converting means, and the adding means. It has a configuration including an inverse logarithmic conversion of the output and a fourth digital signal conversion means for performing a non-linear signal conversion in order to maintain the white balance of the image display element in the entire luminance range.

According to a second aspect of the present invention, an image display device has a fifth digital signal converting means for performing inverse logarithmic conversion of the function of the fourth digital signal converting means according to the first aspect, and white. It has a configuration including a non-linear data input means for dividing the non-linear characteristic data into the sixth digital signal converting means for performing non-linear signal conversion for keeping the balance in the entire luminance range. ing.

An image display apparatus according to claim 3 of the present invention is provided with a comparing means in addition to the image display apparatus according to claim 1 or the image display apparatus according to claim 2, When the D-converted digital image signal is below a predetermined level, the output signal of the first storage means and the output signal of the second storage means are controlled to be fixed to specific values. There is.

[0036]

With the circuit configuration according to the first aspect of the present invention, the conventional multiplication by the ROM table of the video signal and the unit-by-unit equalization correction data multiplication and the line-by-line equalization correction data multiplication are performed by logarithmic conversion. Since it can be realized by addition and inverse logarithmic conversion, it is not necessary to use a large capacity ROM table. In addition, these circuit means can be integrated in a semiconductor such as a standard cell including an A / D converter, which is extremely advantageous in terms of cost and can also save space in terms of board mounting. It is possible to realize an image display device having various correction circuits.

According to the circuit configuration of claim 2,
Even if the relationship between the video signal and the luminance of the image display device changes, the non-linear characteristic can be input, so that the image display device having a flexible correction circuit can be realized.

According to the circuit configuration of claim 3,
When the video signal has low brightness and the multiplication result of the equalization correction can be regarded as no change from the correction data, the value of the equalization correction data can be fixed to a specific value, and thus an image display device having a flexible correction circuit Can be realized.

[0039]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram of a video signal correction circuit of an image display device according to an embodiment of the first aspect of the present invention. Reference numeral 1 is a signal correction circuit for the R signal of the three primary colors of R, G and B. The signal correction circuit for the G signal and the B signal is also the signal correction circuit 1 for the R signal.
Since the configuration and operation are the same, the R signal will be described here, and the G and B signals will not be described.

Reference numeral 11 is an A / D converter for converting an analog video signal into a digital signal, 13 is a memory in which information on the luminance distribution of each image display unit in the image display element is recorded, 1
Reference numeral 5 is an address generation circuit for controlling the memory 13, 14 is a memory in which information of luminance distribution for each line in the image display element is recorded, and 16 is an address generation circuit for controlling the memory 14.

Reference numeral 12 is a first digital signal converting means, which is a ROM table for performing inverse gamma correction and logarithmic conversion on the video signal converted into a digital signal by the A / D converter 11, and 17 is a second digital signal. A ROM table that is a conversion unit that performs logarithmic conversion on the output of the memory 13 that records the luminance distribution information for each unit, and 18 is a third digital signal conversion unit that is a memory that records the luminance distribution information for each line. 14 is a ROM table that performs logarithmic conversion on the output of 14. 19 is the ROM table 12, 17, 18
It is an adder that adds the outputs of the. Reference numeral 20 is a ROM table for performing inverse logarithmic conversion on the output of the adder 19 and nonlinear signal conversion for maintaining the white balance of the image display element in the entire luminance range.

The operation of the video signal correction circuit of the image display device configured as described above will be described below.

The video signal is converted into a digital signal by the A / D converter 11, the Gamma correction for the cathode ray tube is canceled in the ROM table 12, and the logarithmic conversion is further performed. Further, the outputs of the unit correction data memory 13 and the line correction data memory 14 for screen equalization correction are also logarithmically converted by the logarithmic conversion ROM tables 17 and 18, respectively.

The image uniformization correction can be realized by multiplying the video signal, the unit correction data, and the line correction data. However, since each of them is logarithmically converted in the above configuration, after adding these data, the inverse correction is performed. It can be realized by logarithmic conversion. The adder 19 performs this addition. The ROM table 20 performs inverse logarithmic conversion of the output of the adder 19 and then performs non-linear signal conversion in order to maintain the white balance of the image display element in the entire luminance range. Since the ROM table used here can be separately divided for video signal, unit correction, and line correction, it can be realized by a small-capacity ROM.

With such a circuit configuration, gamma correction cancellation, image equalization correction and white balance correction, which have been conventionally realized by a large capacity ROM table, can be realized by a small capacity ROM and adder.

(Embodiment 2) Next, FIG. 2 shows a block diagram of a video signal correction circuit of an image display device according to a second embodiment of the present invention. Since the same reference numerals as those in FIG. 1 described in the first embodiment perform the same operations, the description thereof will be omitted and only different points will be described.

In FIG. 2, reference numeral 21 is a fifth digital signal converting means, which is an RO for inversely logarithmically converting the output of the adder 19.
It is the M table. Reference numeral 22 denotes a sixth digital conversion means, which is a RAM table for performing non-linear signal conversion in order to maintain the white balance of the image display element in the entire brightness range.
Reference numeral 23 is an input circuit for inputting data to the RAM table 22.

According to this embodiment, since the nonlinear signal conversion can be implemented in RAM in order to maintain the white balance of the image display element in the entire luminance range, a correction circuit capable of flexibly responding to changes in the characteristics of the image display element is provided. Can be provided.

(Embodiment 3) Next, FIG. 3 shows a block diagram of a video signal correction circuit of an image display device according to a third embodiment of the present invention. Here, only the points different from FIG. 2 described in the second embodiment will be described.

Reference numeral 24 is a comparison circuit for detecting that the digital video signal is below a predetermined level. Reference numeral 25 is a control circuit for turning off the unit correction when the comparison circuit 24 detects that the video signal is below a predetermined level. Two
Similarly, 6 is a control circuit for turning off the line correction when the comparison circuit 24 detects that the video signal has become lower than a predetermined level.

According to this embodiment, when the video signal becomes low in luminance and cannot be corrected by this method, (when the multiplication result changes by 1 LSB of the video signal, it is better not to perform the multiplication. Since the correction function (which makes the image uniform) can be turned off, it is possible to provide a correction circuit capable of flexibly responding to the characteristics of the image display element.

[0052]

As described above, according to the image display device of the present invention as set forth in claim 1, even if the brightness abnormality occurs due to the variation of the electron beam in the image display unit or the non-equidistant property of two adjacent lines. The image display device can be realized by the small-capacity ROM and the adder by correcting and uniformizing the brightness change on the screen, maintaining the image quality uniformity and white balance in the entire brightness range, and canceling the gamma correction. These circuits can be integrated into a semiconductor such as a standard cell including an A / D converter, which is extremely advantageous in terms of cost, and correction that can save space in terms of board mounting. An image display device having a circuit can be realized.

According to the second aspect of the present invention, the non-linear characteristic can be input even if the relationship between the video signal and the luminance of the present image display device changes, so that an image display device having a flexible correction circuit is provided. Can be realized.

According to the third aspect of the present invention, the value of the uniformized correction data can be fixed to a specific value when the video signal has a low luminance and it can be regarded as uniform without correction. Therefore, an image display device having a flexible correction circuit can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a correction circuit of an image display device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a correction circuit of an image display device according to another embodiment of the present invention.

FIG. 3 is a block diagram of a correction circuit of an image display device according to another embodiment of the present invention.

FIG. 4 is an exploded perspective view of an image display element in a conventional example.

FIG. 5 is an enlarged view of a fluorescent screen of an image display unit of the image display device.

FIG. 6 is a block diagram of a correction circuit in a conventional example.

FIG. 7 is a diagram for explaining video signal conversion for uniform image quality.

[Explanation of symbols]

 1 R signal signal correction circuit 11 A / D converter, 12, 17, 18, 20, 21 ROM table 13 Memory in which information of luminance distribution of each unit is recorded 14 Information of luminance distribution of each line is recorded Memory 15, 16 Address generation circuit 19 Adder 22 RAM table 23 Input circuit 24 Comparison circuit 25, 26 Control circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuji Miwa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Tadayuki Masumi, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yuichi Ishikawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A screen on a screen is horizontally and vertically divided into a plurality of sections, and an electron beam group for irradiating each section is formed on the screen by irradiating a phosphor coated on each section. In an image display device that forms an image with a large number of beam spots, A / D conversion means for converting an image signal into a digital image signal and luminance nonuniformity for each unit section on the screen of the image display device are previously set. The recorded first storage means, the second storage means in which the luminance nonuniformity of each of the plurality of scanning lines of the image display element is recorded in advance, and the inverse gamma correction and the logarithm of the digital image signal. First digital image signal converting means for performing conversion; second digital signal converting means for performing logarithmic conversion on the output signal of the first storage means; Third digital signal converting means for logarithmically converting the output signal of the storing means, the output of the first digital signal converting means, the output of the second digital signal converting means, and the third digital signal. An addition means for adding the outputs of the conversion means and a fourth digital signal conversion means for performing an inverse logarithmic conversion on the output of the addition means and a non-linear signal conversion for keeping the white balance of the image display element in the entire luminance range. An image display device having. 2. The fourth digital signal converting means includes a fifth digital signal converting means for performing an inverse logarithmic conversion and a sixth digital signal converting means for performing a non-linear signal conversion for keeping white balance in the entire luminance range. 2. The image display device according to claim 1, further comprising: a non-linear data input unit for inputting non-linear characteristic data to the sixth digital signal converting unit. 3. A comparison means for inputting the digital image signal A / D converted by the A / D conversion means is provided, and if the digital image signal is below a predetermined level, the output of the first storage means and The output signal of the second storage means is controlled so as to be fixed to a specific value, respectively.
Alternatively, the image display device according to claim 2. 4. The image display device according to claim 1 or 2, wherein a storage means (memory) is used as the first to fifth digital signal conversion means.