JP2003241707A - Image display device and image display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device and an image display method in which fluctuation in driving condition caused by electric resistivity of matrix wiring of a display panel can appropriately be corrected by employing a small amount of hardware. <P>SOLUTION: The device is provided with a means which computes the amount of voltage drop caused by the resistivity of row wiring for inputted image data and computes image data (corrected image data) in which the amount of voltage drop is corrected. Moreover, overflow is prevented by the gain in an overflow processing circuit so that the image data that are corrected do not overflow the input range of a modulation means. Furthermore, saturation characteristic of phosphor is canceled by constituting a gradation converting section which changes the gradation converting characteristic by gain in the preceding stage of the constitution that corrects the effect of the voltage drop. Thus, a high quality image can be displayed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver or a display device for displaying an image by receiving a television signal or a display signal of a computer or the like using a display panel having a plurality of image forming elements arranged in matrix. The present invention relates to an image display device and an image display method.

[0002]

2. Description of the Related Art Conventionally, there are n × m image forming elements arranged in a matrix by wiring m row wirings and n column wirings, and the row wirings are sequentially scanned. ,
By performing the modulation in the column direction, the element groups for one row are simultaneously driven.

In the case of driving in this way, there is a problem in the row wiring due to the voltage drop across the display element due to the voltage drop caused by the electrical resistance of the wiring.

Therefore, in order to correct the decrease in brightness due to the voltage drop due to the wiring resistance of the electric connection wiring to the display element, the correction data is calculated by a statistical calculation to obtain the electron beam required value. A technique relating to an image display device having a configuration for combining correction values is disclosed in Japanese Patent Application Laid-Open No. 8-24892
No. 0 publication.

The configuration of the image display device described in this publication is shown in FIG.
8 shows. The structure relating to the correction of data in this device is roughly as follows. First, 1 of the digital image signal
The luminance data for the lines is added up by the adder 206, and the correction rate data corresponding to this added value is read from the memory 207. On the other hand, the digital image signal is transferred to the shift register 204.
Serial / parallel conversion is performed in the latch circuit 20.
After being held for a predetermined time in 5, the signal is input to the multiplier 208 provided for each column wiring at a predetermined timing. In the multiplier 208, the brightness data and the memory 2 are provided for each column wiring.
The correction data read from 07 is multiplied, and the obtained corrected data is transferred to the modulation signal generator 209, and the modulation signal corresponding to the corrected data is generated by the modulation signal generator 209.
And the image is displayed on the display panel based on the modulated signal. Here, like the summing process of the luminance data of one line of the digital image signal in the summing device 206, statistical calculation processing such as calculating the sum or average is performed on the digital image signal, and this value is set to this value. Correction is made based on this.

[0006]

However, in the above-mentioned conventional structure, a large-scale device such as a multiplier for each column wiring, a memory for outputting correction data, and a summing device for giving an address signal to the memory is required. I needed hardware.

An object of the present invention is to provide an image display device and an image display method capable of suitably correcting a brightness variation and a chromaticity variation due to a variation of driving conditions due to an electric resistance of a matrix wiring of a display panel with a small amount of hardware. To provide.

[0008]

In order to achieve the above object, in the image display device of the present invention, a plurality of row wirings and one column wiring are connected to each one and arranged in a matrix. An image forming element, a scanning means connected to the row wiring, a modulation means connected to the column wiring,
Gradation conversion means for converting the gradation characteristics of the input image data, and image data in which the output of the gradation conversion means is corrected for the influence of the voltage drop caused by the resistance of the row wiring and the scanning means. An image display device comprising: a correction image data calculation unit that calculates correction image data; and a modulation unit that inputs the correction image data and outputs a modulation signal to the column wiring. Is to correct the light emission characteristic of the image forming element when there is no voltage drop.

Further, in the image display device of the present invention,
A plurality of image forming elements connected to each of the plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, and a modulation means connected to the column wirings, Gradation conversion means for converting the gradation characteristics of the input image data, and image data in which the output of the gradation conversion means is corrected for the influence of the voltage drop caused by the resistance of the row wiring and the scanning means. A certain correction image data calculating means for calculating the correction image data, and an amplitude adjustment having a function of multiplying a coefficient for adjusting the amplitude of the correction image data so that the amplitude of the correction image data corresponds to the input range of the modulating means. An image display device including means, the gradation conversion means having gradation conversion characteristics corresponding to the coefficients, and the modulation means by the amplitude adjustment means. As input correction image data integer, and outputs the modulated signal to the column wirings.

Further, in the image display device of the present invention,
A plurality of electron-emitting devices connected to each of the plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, and a modulation means connected to the column wirings, Gradation conversion means for converting the gradation of the input image data, and image data in which the output of the gradation conversion means is corrected for the influence of the voltage drop caused by the resistance of the row wiring and the scanning means. A correction image data calculating unit for calculating the correction image data; and an amplitude adjusting unit having a function of multiplying a coefficient for adjusting the amplitude of the correction image data so that the amplitude of the correction image data corresponds to the input range of the modulating unit. And the gradation conversion means has gradation conversion characteristics corresponding to the coefficient, and the modulation means inputs the corrected image data whose amplitude is adjusted, and outputs a modulation signal to the column wiring. In the image display device according to the present invention, when the uniform image data of each color which is not 0 is input, the pulse width of the pulse output from the modulation means close to the output terminal of the scanning means is from the output terminal of the scanning means. It becomes shorter than the pulse width of the pulse output from the distant modulation means, and further, as a result of canceling the saturation characteristic of the phosphor that depends on the amount of emitted charges of the electron-emitting device, even if any image data of the same color is uniform. It is characterized in that the displayed white color temperature is driven substantially uniformly regardless of the emission brightness.

Further, in the image display method of the present invention,
A plurality of electron-emitting devices connected to each of the plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, a modulation means connected to the column wirings, and the electrons. An image display method using an image display device provided with a phosphor arranged to face an emitting element, wherein emission is performed by correcting the emission characteristic of the phosphor with respect to the amount of emitted charge according to image data that is a luminance required value. A step of calculating a required charge amount value, and a correction for correcting a variation in the emitted charge amount due to an influence of a voltage drop caused by a resistance component of the row wiring and the scanning unit according to the calculated required charge amount value. And a step of calculating image data, wherein the modulating means applies a pulse waveform corresponding to the calculated corrected image data to the column wiring.

Further, in the image display method of the present invention,
A plurality of electron-emitting devices connected to each of the plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, and a modulation means connected to the column wirings. An image display method by an image display device, which performs gradation conversion for canceling a light emission characteristic of an electron-emitting device when there is no voltage drop generated by a resistance component of the row wiring and the scanning means, with respect to input image data. And a step of correcting an influence of a voltage drop caused by a resistance component of the row wiring and the scanning means with respect to an output of the step of performing gradation conversion for canceling the light emission characteristic. A pulse waveform is applied to the column wiring according to the output of the step of correcting the influence of the voltage drop.

Further, in the image display method of the present invention,
A plurality of electron-emitting devices connected to each of the plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, and a modulation means connected to the column wirings. An image display method by an image display device, comprising: a step of converting a gradation characteristic of input image data; and an output of the step of converting the gradation characteristic, wherein Compensating for the effect of the voltage drop that occurs, said modulating means comprising:
An image display method characterized by applying a pulse waveform to the column wiring according to the output of the step of correcting the influence of the voltage drop, the step of correcting the influence of the voltage drop,
The method further comprises the step of adjusting the amplitude so that the output of the step of correcting the influence of the voltage drop falls within the input range of the modulation means, and the step of converting the gradation characteristics corresponds to the input range of the modulation means. Depending on the output of the process of adjusting to
It is characterized in that a part of the characteristics for canceling the light emission characteristics of the electron-emitting device when there is no voltage drop caused by the resistance of the row wiring and the scanning means is selected.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, the shape, the relative arrangement, and the like are not intended to limit the scope of the present invention thereto.

(First Embodiment) (Overall Overview) In a display device in which cold cathode elements are arranged in a simple matrix, a voltage drop occurs due to a current flowing into a scanning wiring and a wiring resistance of the scanning wiring, and a display image is displayed. Is deteriorated. Therefore, the image display device according to the embodiment of the present invention is provided with a processing circuit that appropriately corrects the influence of the voltage drop in the scanning wiring on the display image, and realizes it with a relatively small circuit scale. Configured.

The correction circuit predicts and calculates the deterioration of the display image caused by the voltage drop according to the input image data, obtains the correction data for correcting the deterioration, and corrects the input image data.

As an image display device having such a correction circuit built-in, the inventors have intensively studied an image display device of the following system.

Hereinafter, first, the appearance of the display panel of the image display device according to the embodiment of the present invention, the electrical connection of the display panel, the characteristics of the surface conduction electron-emitting device, the driving method of the display panel, and the electrical resistance of the scanning wiring will be described. The mechanism of the voltage drop caused by it, the correction method and the device for the influence of the voltage drop will be described.

(Overview of Image Display Device) FIG. 1 is a perspective view of a display panel used in the image display device according to the present embodiment, in which a part of the panel is cut away to show the internal structure. . In the figure, 1005 is a rear plate, 1006 is a side wall, 1007 is a face plate, and 1005-
1007 forms an airtight container for maintaining a vacuum inside the display panel.

The rear plate 1005 has a substrate 1001.
, But the cold cathode device 1002 is fixed on the substrate.
Are formed by N × M. Row wiring (scan wiring) 100
3, the column wiring (modulation wiring) 1004 and the cold cathode device are shown in FIG.
Are connected like.

Such a connection structure is called a simple matrix.

A fluorescent film 1008 is formed on the lower surface of the face plate 1007. Since the image display device according to the present embodiment is a color display device, the fluorescent film 1
Red, green, which is used in the field of CRT
Phosphors of three primary colors of blue are painted separately. The phosphor is formed in a matrix corresponding to each pixel (picture element) of the rear plate 1005, and forms a pixel at a position irradiated with an electron (emission current) emitted from the cold cathode element. Is configured.

A metal back 1 is formed on the lower surface of the fluorescent film 1008.
009 is formed.

Hv is a high voltage terminal and is a metal back 100.
9 is electrically connected. By applying a high voltage to the Hv terminal, a high voltage is applied between the rear plate 1005 and the face plate 1007.

In this embodiment, a surface conduction electron-emitting device was prepared as a cold cathode device in the above display panel. A field emission type element can also be used as the cold cathode element. The present invention can also be applied to an image display device in which an element that emits light by itself such as an EL element other than the cold cathode element is connected to a matrix wiring and driven.

(Characteristics of Surface Conduction Type Emitting Element) In the surface conduction type emitting element, as shown in FIG. 3, (emission current Ie) vs. (element applied voltage Vf) characteristics, and (element current If) vs. (element applied voltage). Vf) characteristic. Since the emission current Ie is significantly smaller than the device current If and it is difficult to draw the same current scale, the two graphs are shown on different scales.

The surface conduction electron-emitting device has the following three characteristics regarding the emission current Ie.

First, a certain voltage (this is the threshold voltage Vth
When the above voltage is applied to the element, the emission current Ie rapidly increases, while the emission current Ie is hardly detected at a voltage lower than the threshold voltage Vth.

That is, it is a non-linear element having a clear threshold voltage Vth with respect to the emission current Ie.

Secondly, since the emission current Ie changes depending on the voltage Vf applied to the device, the magnitude of the emission current Ie can be controlled by changing the voltage Vf.

Thirdly, since the cold cathode device has a high-speed response, the emission current I depends on the application time of the voltage Vf.
The release time of e can be controlled.

By utilizing the above characteristics, the surface conduction electron-emitting device can be preferably used in a display device. For example, in the image display device using the display panel shown in FIG. 1, if the first characteristic is used, it is possible to sequentially scan the display screen for display. That is, a voltage equal to or higher than the threshold voltage Vth is appropriately applied to the driven element according to the desired light emission luminance, and the threshold voltage Vt is applied to the non-selected element.
A voltage less than h is applied. By sequentially switching the elements to be driven, it is possible to sequentially scan the display screen for display.

By utilizing the second characteristic,
By the voltage Vf applied to the element, the emission brightness of the phosphor can be controlled and an image can be displayed.

By utilizing the third characteristic,
The light emission time of the phosphor can be controlled by the time for which the voltage Vf is applied to the element, and an image can be displayed.

In the image display device according to the embodiment of the present invention, the modulation is performed using the third characteristic.

(Display Panel Driving Method) FIG. 4 shows an example of the voltages applied to the voltage supply terminals of the scanning wiring and the modulation wiring when the display panel of the image display device according to the embodiment of the present invention is driven.

Now, the horizontal scanning period I is a period in which the pixels in the i-th row emit light.

In order to make the pixel on the i-th row emit light,
The scanning wiring of the i-th row is selected and its voltage supply terminal D
The selection potential Vs is applied to xi. Further, the voltage supply terminals Dxk (k = 1, 2, ... N, where k ≠ i) of the other scanning wirings are set in the non-selected state and the non-selection potential Vns is applied.

In this example, the selection potential Vs is set to -0.5V _SEL which is half the voltage V _SEL shown in FIG. 3, and the non-selection potential Vs is set.
ns is the GND potential.

A pulse width modulation signal having a voltage amplitude Vpwm was supplied to the voltage supply terminal of the modulation wiring. Conventionally, the pulse width of the pulse width modulation signal supplied to the j-th modulation wiring is conventionally i-th row, j-th
The pulse width modulation signal according to the size of the image data of each pixel is supplied to all the modulation wirings, which is determined according to the size of the image data of the pixel of the column.

In the embodiment of the present invention, as will be described later, the pulse width of the pulse width modulation signal supplied to the j-th modulation wiring is corrected in order to correct the decrease in luminance due to the influence of the voltage drop. , The pulse width modulation signal is supplied to all the modulation wirings, which is determined according to the size of the image data of the pixel in the i-th row and the j-th column of the image to be displayed and its correction amount.

In this embodiment, the voltage Vpwm is +
It was set to 0.5V _SEL .

As shown in FIG. 3, the surface conduction electron-emitting device emits electrons when a voltage V _SEL is applied across the device, but does not emit electrons at a voltage lower than Vth.

The voltage Vth is, as shown in FIG.
It is characterized by being larger than 0.5V _SEL .

Therefore, no electrons are emitted from the surface conduction electron-emitting device connected to the scanning wiring to which the non-selection potential Vns is applied.

Similarly, during a period in which the output of the pulse width modulation means is at the ground potential (hereinafter, referred to as a period in which the output is "L"), both ends of the surface conduction electron-emitting device on the selected scanning wiring are detected. Since the voltage applied to Vs is Vs, no electrons are emitted.

The output of the pulse width modulation means is V from the surface conduction electron-emitting device on the scanning wiring to which the selection potential Vs is applied.
Pwm period (hereinafter referred to as "H" period of output)
The electrons are emitted according to the. When the electrons are emitted, the above-mentioned phosphor emits light in accordance with the amount of the emitted electron beam, so that it is possible to emit the brightness corresponding to the emitted time.

The image display device according to the embodiment of the present invention is
An image is displayed by line-sequential scanning and pulse width modulation as described above.

(Regarding Voltage Drop in Scan Wiring) As described above, the fundamental problem faced by the image display device is that the voltage drop in the scan wiring of the display panel causes the potential on the scan wiring to rise and This means that the voltage applied to the conduction type emission element is reduced, and thus the emission current from the surface conduction type emission element is reduced. The mechanism of this voltage drop will be described below.

The device current for one device of the surface conduction electron-emitting device is about several hundred μA when the voltage V _SEL is applied, although it depends on the design specifications and manufacturing method of the surface conduction electron-emitting device.

Therefore, in the case where only one pixel on the selected scanning line is made to emit light and the other pixels are not made to emit light in a certain horizontal scanning period, the device current flowing from the modulation wiring to the scanning wiring of the selected row is 1. Since it is only the current for the pixel (that is, the above-mentioned several 100 μA), there is almost no voltage drop, and the emission brightness does not decrease.

However, in the case where all the pixels in the selected row are made to emit light in a certain horizontal scanning period, the current for all the pixels flows from all the modulation wirings to the scanning wirings in the selected state. The sum is several hundred mA
The number was several A, and a voltage drop occurred on the scanning wiring due to the wiring resistance of the scanning wiring.

If a voltage drop occurs on the scanning wiring, the voltage applied across the surface conduction electron-emitting device will decrease. For this reason, the emission current emitted from the surface conduction electron-emitting device is reduced, and as a result, the emission brightness is reduced.

Further, more complicatedly, the magnitude of the voltage drop has the property of changing within one horizontal scanning period by performing modulation by pulse width modulation.

The pulse width modulation signal supplied to each column is shown in FIG.
Consider a case where a pulse width modulated signal whose pulse width depends on the size of the data and whose rising edge is synchronized with respect to the input data is output as shown in FIG. In such a case, depending on the input image data, generally, within one horizontal scanning period, the number of lit pixels is large immediately after the rise of the pulse, and thereafter, the lit pixels are turned off in order from the lowest brightness. Therefore, the number of lit pixels decreases with time in one horizontal scanning period.

Therefore, the magnitude of the voltage drop generated on the scan wiring also tends to decrease gradually toward the beginning of one horizontal scanning period.

Since the output of the pulse width modulated signal changes at each time corresponding to one gradation of modulation, the temporal change of the voltage drop also changes at each time corresponding to one gradation of the pulse width modulated signal.

The voltage drop in the scanning wiring has been described above.

(Calculation Method of Voltage Drop) Next, a method of correcting the influence of the voltage drop will be described in detail.

In order to obtain the correction amount for reducing the influence of the voltage drop, it is necessary to develop the hardware that predicts the magnitude of the voltage drop and its time change in real time as the first step. However, a display panel of an image display device such as the present invention is generally provided with thousands of modulation wirings, and it is extremely difficult to calculate the voltage drop at the intersection of all the modulation wirings and the scanning wirings. It is very difficult, and it is not very realistic to make hardware that calculates it in real time.

Therefore, the voltage drop amount is obtained by dividing the position of the same row into blocks and also in the amplitude direction of the image data.

Such blocking is based on the following characteristics of voltage drop.

I) At a certain point in one horizontal scanning period, the voltage drop generated on the scan wiring is a spatially continuous amount on the scan wiring, which is a very smooth curve.

Ii) Although the magnitude of the voltage drop varies depending on the display image, it changes at each time corresponding to one gradation of pulse width modulation, and is generally larger at the rising portion of the pulse, and gradually in time. It either becomes smaller or maintains its size.

That is, in the driving method as shown in FIG. 4, the magnitude of the voltage drop does not increase within one horizontal scanning period.

Specifically, the time change of the voltage drop was roughly predicted by calculating the voltage drop by the degenerate model described below for a plurality of times.

(Calculation of voltage drop by degenerate model) FIG.
(A) is a figure for demonstrating the block and node at the time of performing degeneration.

In the figure, for simplification of the drawing, only the selected scanning wiring, each modulation wiring, and the surface conduction electron-emitting device connected to the intersection thereof are shown.

At a certain time in one horizontal scanning period, the lighting state of each pixel on the selected scanning wiring (that is, whether the output of the modulating means is "H" or "L"). Is known.

In this lighting state, the element current flowing from each modulation wiring to the selected scanning wiring is set to Ifi (i =
1, 2 ,. ． ． N and i are defined as column numbers).

Further, as shown in the figure, a block is defined by grouping the n modulation wirings and the intersections of the selected scanning wirings and the surface conduction electron-emitting devices arranged at the intersections thereof. . In this example, the blocks are divided into four blocks.

A position called a node is set at the boundary position of each block. A node is a horizontal position (reference point) for discretely calculating the amount of voltage drop that occurs on the scan wiring in the degenerate model.

In this example, node 0 is placed at the block boundary position.
~ 5 nodes of node 4 were set.

FIG. 5B is a diagram for explaining the degenerate model.

In the degenerate model, n modulation wirings included in one block in FIG. 10A are degenerated to one, and one degenerated modulation wiring is positioned at the center of the block of the scanning wirings. Connected to.

Further, a current source is connected to the modulation wiring of each degenerated block, and the total sum IF0 to IF3 of the current in each block flows from each current source.

That is, IFj (j = 0, 1, ... 3) is

[Equation 1] Is the current expressed as

Further, the potentials at both ends of the scanning wiring are shown in FIG.
However, in the degenerate model, the current flowing into the scanning wiring selected from the modulation wiring is modeled by the above current source, and Vs is Vs in the scanning wiring on the scanning wiring. This is because the voltage drop amount of each part can be calculated by calculating the voltage (potential difference) of each part using the power supply part as a reference (GND) potential.

That is, it is defined as the reference potential for calculating the voltage drop.

The surface conduction electron-emitting device is omitted regardless of the presence or absence of the surface conduction electron-emitting device as long as an equivalent current flows from the column wiring when viewed from the selected scanning wiring. This is because the generated voltage drop itself does not change. Therefore, here, the surface conduction electron-emitting device is omitted by setting the current value flowing from the current source of each block to the total current value of the device currents in each block (Equation 1).

Further, the wiring resistance of the scanning wiring of each block is set to n times the wiring resistance r of the scanning wiring of one section (here, one section is the intersection of the scanning wiring with a certain column wiring and its adjacent portion. In this example, the wiring resistance of the scanning wiring in one section is assumed to be uniform.

In such a degenerate model, the voltage drop amounts DV0 to DV generated at each node on the scanning wiring.
4 is the following sum-of-products formula,

[Equation 2] Can be calculated easily.

That is,

[Equation 3] Is established.

However, aij is a voltage generated at the i-th node when a unit current is injected only into the j-th block in the degenerate model (hereinafter, this is defined as aij).

The above-mentioned aij is derived by Kirchhoff's law, and the result once calculated may be stored as a table.

Further, the summation currents IF0 to IF3 of each block defined by the equation 1 are approximated as shown in the equation 3.

[0087]

[Equation 4] However, in the above equation, Count i is a variable that takes 1 when the i-th pixel on the selected scanning line is in the lighting state and 0 when it is in the unlit state.

IFS is the amount obtained by multiplying the device current IF flowing when the voltage V _SEL is applied across the one surface conduction electron-emitting device by a coefficient α taking a value between 0 and 1.

That is,

[Equation 5] Was defined.

Equation 3 assumes that a device current proportional to the number of lights in the block flows into the selected scan line from the column line of each block. At this time, the element current IF of one element is multiplied by the coefficient α to obtain the element current IFS of one element for the following reason. Originally, in order to calculate the amount of voltage drop, it is necessary to repeatedly calculate the voltage increase of the scanning wiring due to the voltage drop and the decrease amount of the device current due to it, but this convergence calculation is performed by hardware. Is not realistic. Therefore, in the present invention, αIF is approximately used as the convergence value of IF. Specifically, the rate of decrease in IF (= α1) when the amount of voltage drop is maximum (all white) and the rate of decrease in IF (= α2) when the amount of voltage drop is (minimum = 0). ) And estimate α1
And the average value of α2 or 0.8 × α1.

FIG. 5C shows an example of the result of calculation of the voltage drop amounts DV0 to DV4 of each node by the degeneration model in a certain lighting state.

Since the voltage drop has a very smooth curve, it is assumed that the voltage drop between the nodes takes a value approximately as shown by the dotted line in the figure.

As described above, by using this degenerate model, it is possible to calculate the voltage drop at the node position at a desired time point with respect to the input image data.

As described above, the voltage drop amount in a certain lighting state was simply calculated using the degeneration model.

The voltage drop generated on the selected scanning wiring changes with time within one horizontal scanning period. As described above, with respect to some times during one horizontal scanning period, the voltage drop occurs at that time. The lighting state was calculated and the voltage drop was calculated using the degeneration model for the lighting state.

The number of lights in each block at a certain point in one horizontal scanning period can be easily obtained by referring to the image data of each block.

As an example, assume that the number of bits of input data to the pulse width modulation circuit is 8 bits, and the pulse width modulation circuit outputs a pulse width according to the size of the input data.

That is, when the input data is 0, the output is "L", when the input data is 255, "H" is output during one horizontal scanning period, and when the input data is 128, one horizontal scanning period is output. It is assumed that "H" is output in the first half period and "L" is output in the second half period.

In such a case, the number of lights at the start time of the pulse width modulation signal (rising time in the example of the modulation signal of this example) is counted when the input data to the pulse width modulation circuit is greater than 0. It can be easily detected.

Similarly, the number of lights at the center time of one horizontal scanning period can be easily detected by counting the number of input data to the pulse width modulation circuit which is larger than 128.

In this way, by comparing the image data with a certain threshold value and counting the number of true outputs of the comparator, the number of lightings at any time can be easily calculated.

Here, in order to simplify the following description, a time amount called a time slot is defined.

That is, the time slot represents the time from the rise of the pulse width modulated signal in one horizontal scanning period, and the time slot = 0 represents the time immediately after the start time of the pulse width modulated signal. Define as a thing.

Time slot = 64 is defined as a time when 64 gradations have elapsed from the start time of the pulse width modulation signal.

In the present example, the pulse width modulation is an example in which the pulse width from the rising time is used as the reference, and the pulse width is modulated based on the falling time of the pulse. However, it goes without saying that the same can be applied, although the advancing direction of the time axis is opposite to the advancing direction of the time slot.

(Calculation of Correction Data from Voltage Drop Amount) As described above, the time change of the voltage drop during one horizontal scanning period is approximately and discretely calculated by repeatedly performing the degeneracy model. I was able to.

FIG. 6 shows an example in which the voltage drop is repeatedly calculated for certain image data, and the time change of the voltage drop in the scan wiring is calculated (the voltage drop shown here and its time change are , An example for one image data, and it is natural that the voltage drop for another image data has another change.

In the figure, time slots = 0, 64, 12
The voltage drop at each time was calculated discretely by applying the degenerate model to each of the four time points of 8, 192.

In FIG. 6, the voltage drop amount at each node is connected by a dotted line, but the dotted line is shown to make the diagram easier to see, and the voltage drop calculated by this degenerate model is □, ○, ●. , Δ were calculated discretely at the positions of the nodes.

The inventors examined a method of calculating correction data for correcting image data from the amount of voltage drop as the next step after the magnitude of voltage drop and its change over time can be calculated.

FIG. 7 is a graph in which the emission current emitted from the surface conduction electron-emitting device in the lighting state is estimated when the voltage drop shown in FIG. 6 occurs on the selected scanning wiring.

The vertical axis represents the amount of the emission current at each position for each time in percentage, with the magnitude of the emission current emitted when there is no voltage drop being 100%, and the horizontal axis represents the horizontal position. There is.

As shown in FIG. 7, at the horizontal position (reference point) of node 2, the emission current at time slot = 0 is Ie0, the emission current at time slot = 64 is Ie1, and time slot = 128. The emission current at time is Ie2, and the emission current at time slot 192 is Ie3.

FIG. 7 was calculated from the graph of the voltage drop amount of FIG. 6 and the “driving voltage vs. emission current” of FIG. Specifically, it is a mechanical plot of the value of the emission current when a voltage obtained by subtracting the voltage drop amount from the voltage V _SEL is applied.

Therefore, this figure only means the current emitted from the surface conduction electron-emitting device in the lighting state, and the surface conduction electron-emitting device in the off state does not emit current.

A method for calculating correction data for correcting image data from the voltage drop amount will be described below.

(Correction Data Calculation Method) FIG. 8 (a),
(B), (c) is a figure for demonstrating the method of calculating the correction data of a voltage drop amount from the time change of the emission current of FIG. The figure shows an example of calculating correction data for image data of size 64.

The emission amount of luminance is nothing but the emitted charge amount obtained by temporally integrating the emission current by the emission current pulse.
Therefore, in the following, when considering the variation of the brightness due to the voltage drop, the description will be given based on the amount of the emitted charges.

If the emission current when there is no influence of the voltage drop is IE and the time corresponding to one gradation of the pulse width modulation is Δt, the emission current pulse when the image data is 64 is emitted by the emission current pulse. The amount of emitted charge Q0 to be performed is obtained by multiplying the amplitude IE of the emitted current pulse by the pulse width (64 × Δt),

[Equation 6] Can be expressed as

However, in reality, a phenomenon occurs in which the emission current is reduced due to the voltage drop on the scanning wiring.

The amount of charge emitted by the emission current pulse considering the influence of the voltage drop can be calculated approximately as follows. That is, the emission currents of the time slots = 0 and 64 of the node 2 are Ie0 and Ie1, respectively. If the emission current between 0 and 64 is approximated to linearly change between Ie0 and Ie1, the emission during this period is approximated. The charge amount Q1 is shown in FIG.
The area of the trapezoid.

That is,

[Equation 7] Can be calculated as

Next, as shown in FIG. 8C, when the pulse width is extended by DC1 in order to correct the decrease in the emission current due to the voltage drop, it is assumed that the effect of the voltage drop can be removed.

When the voltage drop is corrected and the pulse width is extended, the amount of emission current in each time slot is considered to change, but here, for simplification,
As shown in FIG. 8C, it is assumed that the emission current is Ie0 at time slot = 0 and the emission current at time slot = (64 + DC1) is Ie1.

Further, the emission current between the time slot 0 and the time slot (64 + DC1) is approximated to take a value on a line connecting the emission currents at two points with a straight line.

Then, the emission charge amount Q2 due to the corrected emission current pulse is

[Equation 8] Can be calculated as

If this is equal to Q0, then

[Equation 9] Becomes

If this is solved for DC1,

[Equation 10] Becomes

In this way, the correction data when the image data is 64 was calculated.

That is, the size of the position of node 2 is 64
For the image data of
The correction amount CData may be added by a = DC1.

Similarly, for image data of 128 in size, two periods as shown in FIG. 9 and for image data of 192 in three periods as shown in FIG. The correction amount can be calculated for each of the periods.

When the pulse width is 0, of course, there is no influence of the voltage drop on the emission current, so the correction data is set to 0 and the correction data CData is added to the image data.
Is also 0.

Note that 0, 64, 128, 19
The reason why correction data is calculated for discrete image data as in 2 is to reduce the amount of calculation.

An example of discrete correction data for certain input image data obtained by this method is shown in FIG. 11 (a). In the figure, the horizontal axis corresponds to the horizontal display position, and the position of each node is described. The vertical axis represents the size of the correction data.

The discrete correction data are calculated for the positions of the nodes indicated by □, ○, ●, and Δ in the figure and the size of the image data Data (image data reference value = 0, 64, 128, 192). It is a thing.

(Interpolation Method of Discrete Correction Data) The correction data calculated discretely is discrete with respect to the position of each node and does not give the correction data at any horizontal position (column wiring number). Absent. At the same time, it is correction data for image data having some predetermined reference image data size at each node position, and does not give correction data according to the actual image data size. .

Therefore, the inventors calculated the correction data suitable for the size of the input image data in each column wiring by interpolating the correction data calculated discretely.

FIG. 11B is a diagram showing a method for calculating the correction data corresponding to the image data Data at x located between the node n and the node n + 1.

As a premise, it is assumed that the correction data has already been discretely calculated at the positions Xn and Xn + 1 of the nodes n and n + 1.

Data as input image data has a value between the image data reference values Dk and Dk + 1.

Now, the discrete correction data for the reference value of the k-th image data of the node n is set to CData [k] [n].
The correction data CA of the pulse width Dk at the position x can be expressed as CData [k] [n] and CData.
Using the values of [k] [n + 1], the following can be calculated by linear approximation.

That is,

[Equation 11] Becomes

However, Xn and Xn + 1 are horizontal display positions of the nodes n and (n + 1), respectively, and are constants determined when the above-mentioned block is determined.

Further, the image data Dk + 1 at the position x
The correction data CB of can be calculated as follows.

That is,

[Equation 12] Becomes

By linearly approximating the correction data of CA and CB, the correction data CD for the image data Data at the position x can be calculated as follows.

That is,

[Equation 13] Becomes

As described above, in order to calculate the correction data suitable for the actual position and the size of the image data from the discrete correction data, the calculation can be easily performed by the method described in the expressions 9 to 11.

The broken line connecting the nodes in FIG. 11A is the result of interpolating the discrete correction data by the above calculation. As can be seen from the figure, in the voltage drop correction method of the present invention, no voltage drop occurs when the image data is 0, so the same correction data is calculated for the position x (of course, the correction data may be 0). For the same image data whose image data is not 0, correction data having a gentle distribution is calculated for the position x, that is, the horizontal direction of the screen. However, when the direction of the scanning line is the vertical direction of the screen, the correction data has a gentle distribution in the vertical direction of the screen.

If the correction data calculated in this way is added to the image data to correct the image data and pulse width modulation is performed according to the corrected image data (referred to as corrected image data), the conventional problems It is possible to reduce the influence of the voltage drop on the displayed image, and it is possible to improve the image quality.

The hardware for correction, which has been a problem from the beginning, can be reduced in size by introducing approximations such as degeneracy described so far. It had an excellent merit that it could be configured with hardware.

(Explanation of Function of Entire System and Each Part) Next, the hardware of the image display device incorporating the correction data calculating means will be explained.

FIG. 12 is a block diagram showing an outline of the circuit configuration. In the figure, 1 is the display panel of FIG. 1, Dx1
˜DxM and Dx1 ′ to DxM ′ are voltage supply terminals of the scanning wiring of the display panel, Dy1 to DyN are voltage supply terminals of the modulation wiring of the display panel, and Hv is for applying an acceleration voltage between the face plate and the rear plate. High voltage supply terminal,
Va is a high-voltage power supply, 2 is a scanning circuit, 3 is a synchronization signal separation circuit, 4 is a timing generation circuit, 7 is a conversion circuit for converting the YPbPr signal into RGB by the synchronization separation circuit 3,
Reference numeral 23 is a selector for switching between a television video signal and a computer video signal, 17 is an inverse γ processing unit, 5
Is a shift register for one line of image data, 6 is a latch circuit for one line of image data, 8 is pulse width modulation means for outputting a modulation signal to the modulation wiring of the display panel, 12 is an adder, and 14 is correction data calculation means. , 20 is a maximum value detecting unit, 21 is a gain calculating unit, and 200 is a gradation converting unit.

The gradation conversion unit 200 will be described later, so
In the following description, it is assumed that the gradation conversion unit 200 is not provided.

Further, in the figure, R, G and B are RGB parallel input image data, Ra, Ga and Ba are RGB parallel image data subjected to an inverse γ conversion process which will be described later, and D.
ata is image data subjected to parallel / serial conversion by the data array conversion unit, CD is correction data calculated by the correction data calculating unit, and Dout is image data corrected by adding the correction data to the image data by the adder. (Corrected image data).

(Synchronous Separation Circuit, Selector) The image display device according to the present embodiment is NTSC, PAL, SECAM, H.
It is possible to display a television signal such as a DTV and a VGA output from a computer together.

In the HDTV system video signal, the sync separation circuit 3 first separates the sync signals Vsync and Hsync and supplies them to the timing generation circuit. The video signals separated by synchronization are supplied to the RGB conversion means. Inside the RGB conversion means, a YPbPr-to-RGB conversion circuit, a low-pass filter (not shown), an A / D converter, and the like are provided. The YPbPr is converted into a digital RGB signal, and the converted signal is sent to the selector 23. Is being supplied.

A video signal output from a computer such as VGA is A / D converted by an A / D converter (not shown),
It is supplied to the selector 23.

The selector 23 selects a television signal based on which video signal the user wants to display.
The computer signal is appropriately switched and output.

(Timing Generation Circuit) The timing generation circuit is a circuit which has a built-in PLL circuit, generates timing signals corresponding to various video formats, and generates operation timing signals for each section.

The timing signal generated by the timing generation circuit 4 includes Tsft for controlling the operation timing of the shift register 5, the shift register, and the latch circuit 6.
Control signal Dataalo for latching data to
d, pulse width modulation start signal Pwmstar of the modulation means 8
t, a clock Pwmclk for pulse width modulation, Tscan for controlling the operation of the scanning circuit 2, and the like.

(Scanning Circuit) As shown in FIG. 13, the scanning circuits 2 and 2'are arranged to sequentially scan the display panel row by row in one horizontal scanning period, so that the selection potential Vs is applied to the connection terminals Dx1 to DxM. Alternatively, it is a circuit which outputs the non-selection potential Vns.

The scanning circuits 2 and 2 ′ are circuits which perform scanning by sequentially switching the selected scanning wiring every horizontal period in synchronization with the timing signal Tscan from the timing generation circuit 4.

Incidentally, Tscan is a timing signal group made up of a vertical synchronizing signal and a horizontal synchronizing signal.

The scanning circuits 2 and 2'are each composed of M switches and shift registers as shown in FIG. These switches are preferably composed of transistors or FETs.

In order to reduce the voltage drop in the scanning wiring, it is preferable that the scanning circuit is connected to both ends of the scanning wiring of the display panel and driven from both ends as shown in FIG.

On the other hand, the embodiment of the present invention is effective even when the scanning circuit is not connected to both ends of the scanning wiring, and can be applied only by changing the parameter of Expression 2.

(Inverse γ Processing Section) The CRT has a light emission characteristic of approximately 2.2 to the input (hereinafter referred to as an inverse γ characteristic).

Such characteristics of the CRT are taken into consideration in the input video signal, and the input video signal is generally converted in accordance with the .gamma. Characteristic of the 0.45th power so as to have a linear emission characteristic when displayed on the CRT.

On the other hand, when the display panel of the image display device according to the embodiment of the present invention has a light emission characteristic which is substantially linear with respect to the application time when it is modulated by the application time of the drive voltage, the input video signal Needs to be converted based on the inverse γ characteristic (hereinafter referred to as the inverse γ conversion).

The inverse γ processing section shown in FIG. 12 is a block for performing inverse γ conversion on the input video signal.

The inverse γ processing section of this embodiment is configured by a memory for the inverse γ conversion processing.

The inverse γ processing unit sets the number of bits of the video signals R, G, B to 8 bits, and the number of bits of the video signals Ra, Ga, Ba output from the inverse γ processing unit is also 8 bits.
It is configured by using a memory having an address of 8 bits and a data of 8 bits for each color (FIG. 14).

(Data Array Converter) Data Array Converter 9
Is a circuit for performing parallel / serial conversion of RGB parallel video signals Ra, Ga, Ba according to the pixel array of the display panel. The configuration of the data array converter 9 is shown in FIG.
As shown in, the FIFO (First
In First Out) memory 2021R, 20
21G, 2021B and a selector 2022.

Although not shown in the figure, the FIFO memory includes two horizontal pixel memory words for odd lines and even lines. When the video data of the odd line is input, the data is written in the FIFO for the odd line, while the image data accumulated in the previous horizontal scanning period is read from the FIFO memory for the even line. When the video data of the even-numbered lines is input, the data is written in the FIFO for the even-numbered lines, while the image data accumulated in the previous horizontal period is read from the FIFO memory for the odd-numbered lines.

The data read from the FIFO memory is parallel / serial converted by the selector according to the pixel array of the display panel and output as RGB serial image data SData. Although not described in detail, it operates based on the timing control signal from the timing generation circuit 4.

(Delay Circuit 19) The image data SData rearranged by the data array converter is input to the correction data calculating means and the delay circuit 19. The correction data interpolating unit of the correction data calculating means, which will be described later, refers to the values of the horizontal position information x and the image data SData from the timing control circuit, and calculates the correction data CD suitable for them.

The delay circuit 19 is provided to absorb the time required for the correction data calculation (the above-mentioned correction data interpolation processing), and when the correction data is added to the image data by the adder, the image data It is a means for delaying so that the correction data corresponding to that is correctly added. The same means can be configured by using a flip-flop.

(Adder 12) The adder 12 is means for adding the correction data CD from the correction data calculating means and the image data Data. Image data D can be obtained by adding
ata is corrected and transferred to the maximum value detection circuit and the multiplier as corrected image data Dout.

The number of bits of the corrected image data output from the adder is preferably determined so that overflow does not occur when the correction data is added to the image data.

More specifically, the image data Data is 8
It has a data width of bits, the maximum value is 255, the correction data CD has a data width of 7 bits, and the maximum value is 1
Suppose it was 20.

At this time, the maximum value of the addition result is 255 + 1
20 = 375.

(Overflow Processing) In the embodiment of the present invention, the correction is realized by the corrected image data obtained by adding the calculated correction data to the image data, as described above.

Now, it is assumed that the number of bits of the modulation means is 8 and the number of bits of the corrected image data Dout which is the output of the adder is 10 bits.

Then, if the corrected image data is directly connected to the input of the modulation means, an overflow will occur.

Therefore, it is necessary to adjust the amplitude of the corrected image data before it is input to the modulation means.

As a structure for preventing overflow, an all-white pattern in which the input image data is maximum ((R, G, B) =
The maximum value of the corrected image data when (FFh, FFh, FFh)) is input may be estimated in advance, and the corrected image data may be multiplied by a gain such that the maximum value falls within the input range of the modulation means.

Hereinafter, this method will be referred to as the fixed gain method.

In the fixed gain method, overflow does not occur, but an image with a low average luminance is multiplied by a small gain even though it can be displayed with a larger gain, so the luminance of the displayed image is dark. May be.

On the other hand, the maximum value of the corrected image data for each frame is detected, a gain is calculated such that this maximum value falls within the input range of the modulation means, and the gain is multiplied by the corrected image data to prevent overflow. You may.

Hereinafter, this method will be referred to as an adaptive gain method.

In the adaptive gain method, corrected image data Do
Maximum value detection means 20 for detecting the maximum value MAX of each frame of ut, gain calculation means 21 for calculating a gain G1 for multiplying the corrected image data by the maximum value, and corrected image data Dout and gain. A multiplier or the like for multiplying G1 is required.

In the adaptive gain method, it is preferable to calculate the gain for preventing overflow in units of frames.

For example, a gain can be calculated for each horizontal line to prevent overflow, but in that case, a difference in gain for each horizontal line causes an uncomfortable feeling in a displayed image, which is not preferable.

The outline of the fixed gain method and the adaptive gain method has been described above.

The inventors have confirmed that the amplitude of the corrected image data can be adjusted appropriately even if the gain is calculated by any method.

Therefore, in this embodiment, the amplitude is adjusted by the adaptive gain method.

Hereinafter, in this embodiment, the circuit configuration for adjusting the amplitude of the corrected image data by the adaptive gain method will be described in detail.

(Maximum value detecting means 20) The maximum value detecting means 20 of the present invention is connected to each part as shown in FIG.

The same means is a circuit which can be easily constructed by a comparator and a register. The means compares the value stored in the register with the size of the correction image data sequentially transferred, and if the correction image data is larger than the value of the register, the value of the register is set to that data value. This is the circuit to be updated.

If the register value is cleared to 0 at the beginning of the frame, the maximum value of the corrected image data in the frame is stored in the register at the end of the frame.

The maximum value of the corrected image data thus detected is transferred to the gain calculating means 21.

(Gain calculation means) Gain calculation means 21
Is the corrected image data Dout based on the adaptive gain method.
Is a means for calculating a gain for adjusting the amplitude so that it falls within the input range of the modulating means.

As for the gain, the maximum value detected by the maximum value detecting means 20 is MAX, and the maximum value in the input range of the modulating means is INM.
If you say AX,

[Equation 14] It may be determined so that (1st method).

The gain calculating means 21 updates the gain in the vertical blanking period and changes the gain value for each frame.

In the configuration of the image display device according to the embodiment of the present invention, the maximum value of the corrected image data of the previous frame is used to calculate the gain by which the corrected image data of the current frame is multiplied. Has become.

Therefore, strictly speaking, overflow may occur due to the difference in the corrected image data for each frame.

To solve such a problem, a limiter means to be described later is provided for the output of the multiplier for multiplying the corrected image data by the gain, and the circuit is designed so that the output of the multiplier is within the input range of the modulating means. I liked it.

It can be considered that the overflow processing is performed by utilizing the correlation of the corrected image data (image data) between the adjacent frames.

If a frame memory is provided between the maximum value detection circuit and the multiplier, overflow can be prevented with a structure having no time delay.

Further, the present inventors have confirmed that the gain determination method of the adaptive gain method may calculate the gain by the following method.

That is, as the gain to be applied to the corrected image data of the current frame, the maximum value of the corrected image data detected in the frame before the current frame is smoothed (averaged) in the frame direction, and the average thereof is calculated. For the value AMAX,

[Equation 15] It may be determined so that (2nd method).

In the third method, the current gain may be calculated by calculating the gain G1 for each frame by the expression 12 and averaging the gains.

The inventors have confirmed that any of these three methods is preferable, while the second and third methods are more suitable than the first method. This is very preferable because it has another effect that the flicker in is greatly reduced (this will be described later with reference to FIG. 16).

The inventors examined the number of frames to be averaged with respect to the second method and the third method. For example, averaging 16 to 64 frames has less flicker, which is preferable. An image was obtained.

In the case of the second and third methods, as in the first method, the (corrected) image data has a correlation between frames, so that the probability of occurrence of overflow can be reduced. However, it cannot completely prevent overflow.

As a countermeasure for this, it is more preferable that the overflow is roughly prevented by the above-mentioned method, and a limiter is provided at the output of the multiplier to completely prevent the overflow.

FIG. 16 is a diagram for explaining the flicker by taking the first method and the second method as an example.

The figure is an example of a moving image in which a white bar rotates counterclockwise in a gray background. When such an image is displayed, the size of the correction data CD changes for each frame as the rod rotates.

FIG. 17 is a diagram for explaining corrected image data when such a moving image is corrected. In the same figure, among the respective corrected image data, the maximum one in each frame is extracted and graphed.

The white portion in the figure corresponds to the original image data, and the gray portion corresponds to the portion expanded by the correction.

When an image as shown in FIG. 16 is displayed, the maximum value of the corrected image data of consecutive frames fluctuates as shown in FIG.

Therefore, if the gain is set for each frame as shown in Expression 12, the gain variation for each frame becomes severe as shown in FIG. A flicker feeling occurs.

On the other hand, when the gain is determined by the equation 13, since the gain is averaged, the fluctuation of the gain is small and the fluctuation of the luminance is small as shown in FIG. There was an excellent effect that the feeling was reduced.

[0225] In the figure (b), the graph with white circles is the expression 1
The gain according to 2 and the black circle graph are the averaged gain according to Expression 13.

Although the third method has not been discussed in detail here, the inventors have confirmed that flicker is reduced because the gain variation is small as in the second method.

Further, the gain calculating means 21 averages the gains on the screens of the continuous scenes as described above, but on the other hand, when the scene of the image is changed, the scene is changed. It was preferable to quickly change the gain.

On the other hand, the gain calculating means 21 sets a preset threshold value which is the scene switching threshold value Gth, and the gain of the previous frame calculated by the expression 12 is GB, and the maximum value of the previous frame is GB. Value detection means 2
If the absolute value of the difference between GN and GN-GB calculated by Equation 12 from the detected maximum value of the corrected image data of 0 is ΔG, and ΔG = | GN-GB |> Gth, the gain G1 = While calculating as (GN-GB) × A + GB, if ΔG = | GN-GB | ≦ Gth, gain G1 = (GN-GB) × B + GB (where A and B are values of 1 ≧ A ≧ B> 0 With a real number)
As a result, the gain of the next frame was smoothed and calculated, which was preferable.

Particularly, as the values of A and B, A = 1 and B
= 1/16 to 1/64 is preferable.

(Multiplier) Gain G1 calculated by the gain calculating means and corrected image data Dout which is the output of the adder
Is multiplied by the multiplier of FIG. 12 and transferred to the limiter circuit as corrected image data Dmulti having the adjusted amplitude.

(Limiter Means) There is no problem if the gain can be determined so that overflow does not occur as described above, but according to the above-described several gain determination methods,
Since it is difficult to determine the gain so that overflow does not occur, it is possible to provide a limiter.

The limiter has a preset limit value and compares the output data Dmulti input to the limiter with the limit value. If the limit value is smaller than the output data, the limit value is output and the limit value is output. If the limit value is large, the output data is output (the signal name in FIG. 12 is the corrected image data Dlim).

The corrected image data Dlim completely limited to the input range of the modulation means by the limiter means is supplied to the modulation means via the shift register and the latch.

(Gradation conversion means) The gradation conversion section 20 of FIG.
Before showing the details of the operation of 0, the case where an image display device which does not correct the influence of the voltage drop and does not use the gradation conversion unit 200 is realized will be described.

The inventors of the present invention, in the image display device having the structure in which the effect of the voltage drop is not corrected and the gradation conversion unit 200 is not provided,
The following phenomena were confirmed.

That is, A. The number of gradations of image data (pulse width to drive) is 255
Image data (dark picture) with a smaller number of gradations is compared with the case where a small area is displayed (with an 8-bit data width).
B. Displayed reddish The number of gradations of image data (pulse width to drive) is 255
This is a phenomenon in which the entire screen is displayed reddish when displayed with a gradation number of image data of 255, as compared with the case where a minute area is displayed (with an 8-bit data width).

The present inventors analyzed these phenomena as follows.

That is, the emission efficiency of the red phosphor tends to be saturated when the amount of input charge is large. Therefore, when the gradation number of the image data is 255 and the minute area is displayed, the saturation is increased. That is, since the voltage drop in the scanning wiring is small, the emission current is large, and the electrons collide with the phosphor for a relatively long time, so that the amount of input charges is large and the red phosphor is saturated. Therefore, based on the case where the number of gradations of the image data is 255 and the minute area is displayed,
The above A. B. In this case, since the amount of charge injected into the red phosphor was small, the saturation of the red phosphor was small and the emission intensity of red was relatively large, and as a result, the display image was displayed as reddish.

FIG. 19 is a schematic diagram showing the gradation characteristics when the voltage conversion is not corrected and the gradation conversion section is not provided.

In FIG. 19, the horizontal axis represents the pulse width with which the modulation means drives the modulation wiring, and the vertical axis represents the number of gradations of the image data.
It is the normalized luminance normalized by the luminance of each color when a minute area is displayed at 55 (when there is almost no voltage drop in the scanning wiring). In FIG. 19, a1gb is the gradation characteristic of green and blue when there is almost no voltage drop in the scanning wiring, and a1gb
r is a gradation characteristic of red when there is almost no voltage drop in the scanning wiring.

Further, in FIG. 19, c1gb is the gradation characteristic of green and blue when the maximum voltage drop occurs when all the display elements on the scanning wiring are turned on, and c1r is the entire display on the scanning wiring. It is the gradation characteristic of red when the maximum voltage drop occurs when the element is turned on.

The values of c1gb and c1r are normalized by the brightness when the gradation number of the image data is 255 and a minute area is displayed. In the figure, when the drive pulse width is 255, the normalized luminances of green and blue are ¼.

In FIG. 19, b1gb is a gradation characteristic of green and blue when a voltage drop occurs in which an intermediate brightness between the brightness of a1gb and the brightness of c1gb occurs, and b1r is a gradation characteristic of red at the same voltage. is there. Similarly, the brightness when the number of gradations of the image data is 255 and the minute area is displayed is normalized.

The characteristics of the luminance and drive pulse width (value of corrected image data) shown in FIG. 19 change depending on the amount of voltage drop, and the drive voltage of the electron-emitting device when an actual image is displayed is It was difficult to realize a conversion that changes depending on the position of the element and completely cancels the above characteristics.

As a result of intensive studies, the present inventors have found the following in driving in which the influence of the voltage drop of the display panel using the surface conduction electron-emitting device is corrected.

(1) The method according to the embodiment of the present invention for correcting the influence of the voltage drop is the pulse width determined by the image data in the emission current amount IE when there is no voltage drop with respect to the input image data. Calculate the data (corrected image data) with the pulse width adjusted so that the amount of emitted charge is multiplied by
The modulation means drives the display panel with the pulse width.

(2) When the maximum value of the corrected image data exceeds the input range of the modulation means, overflow processing is performed and the corrected image data is multiplied by the gain. Then, the corrected image data is stored in the input range of the modulation means.

(3) The saturation characteristics of the phosphor (particularly the characteristics of the red phosphor) are almost determined by the amount of emitted charge in the pulse width of the condition for actually driving the display panel and the emission current value of the electron-emitting device. It was a characteristic.

That is, (1) is "when the influence of the voltage drop is corrected, there is no voltage drop regardless of the voltage drop occurring in the actual display panel or the actual pulse width being driven. Of the emission current IE is multiplied by the pulse width determined by the image data to enter the phosphor. "(I.e., the variation of the emission charge amount is corrected so that the amount of charge corresponds to the image data). It is shown that the emitted charge amount is corrected.

(2) "In the case of overflow processing, the emission charge amount obtained by multiplying the emission current IE in the case where there is no voltage drop by the pulse width determined by the value obtained by multiplying the gain of the image data is incident on the phosphor." Is shown.

Further, (3) shows that the saturation characteristic of the phosphor (particularly the characteristic of the red phosphor) can be determined only by the amount of emitted charge.

In consideration of the features (1), (2) and (3), an image display device having a gradation conversion section 200 has been invented.

Before describing the actual configuration of the gradation conversion unit 200, the outline of the gradation conversion characteristics of the gradation conversion unit 200 will be described.

In FIG. 20, the horizontal axis represents the amount of emitted charges emitted by the surface conduction electron-emitting device, and the vertical axis represents the brightness of each color. Figure 2
0, in order to simplify the description, the emission current amount IE when there is no voltage drop is set to the time Δ for one gradation of pulse width modulation.
The amount of electric charge input by t is 1, and the amount of electric charge emitted on the horizontal axis is normalized. As a result of the normalization, the maximum value of the emitted charge amount is 255. That is, the emission charge amount (maximum emission charge amount) when the drive pulse width of the modulator is 255 (maximum) and a minute region is displayed (when there is almost no voltage drop in the scanning wiring) is 255.

The vertical axis is the emission current amount IE when there is no voltage drop, and is normalized so that the brightness of each color is 1 when the pulse width is 255 gradations (255 × Δt).

By correcting the influence of the voltage drop in the embodiment of the present invention, the emission charge amount obtained by multiplying the emission current amount IE when there is no voltage drop by the pulse width determined by the image data is incident on the phosphor. The pulse width is adjusted as described above (feature (1)).

Therefore, when the influence of the voltage drop is corrected, the horizontal axis corresponds to 0 to 255 of the image data.

In FIG. 20, qgb is a gradation characteristic of green and blue, and qr is a gradation characteristic of red. In FIG. 20, for example, the pulse width and the emission current (driving voltage) may be changed and actually measured.

When the overflow process is not performed, the amount of emitted electric charge is equivalent to the image data, so it is understood that the gradation conversion that cancels the characteristic of FIG. 20 may be performed on the image data. Therefore, as a characteristic of the gradation conversion unit 200, FIG.
By having the conversion characteristic for canceling the gradation characteristic of, it is possible to cancel the above-described problem that the display is reddish.

FIG. 21 shows gradation conversion characteristics for canceling the actual characteristics of FIG. The figure shows the case where the input and output are 8-bit data. In FIG. 21, QGB is
A characteristic curve for canceling the saturation characteristics of the green and blue phosphors (indicated by a straight line in the present example as not saturated), QR is a characteristic curve for canceling the saturation characteristics of the red phosphor shown by qr in FIG. Is.

As described above, since the image data corresponds to the emitted charge amount (feature (1)), it is possible to cancel the characteristic of the red phosphor having the saturation characteristic depending on the emitted charge amount. Could be realized by gradation conversion of image data.

That is, the gradation conversion of the image data is
This means that the image data, which is the brightness required value, is converted into the emission charge amount required value in consideration of the emission characteristics of the phosphor.

Then, it is shown that the emission charge amount is corrected to correct the variation in the emission charge amount so that the emission charge amount required value is obtained.

Next, the case where the overflow process is performed will be described. Due to the feature (2) described above, the emission charge amount obtained by multiplying the emission current amount IE when there is no voltage drop by the pulse width determined by the value obtained by multiplying the gain (coefficient) of the image data is incident on the phosphor.

That is, even if the input image data is the same, the amount of emitted charge is multiplied by the gain when the overflow processing is performed as compared with the case where the overflow processing is not performed.

FIG. 22 shows the characteristic of normalized charge amount vs. luminance for the purpose of explaining the details. Similarly to FIG. 20, FIG. 22 also shows the emission current amount IE in the case where there is no voltage drop by normalizing the emission charge amount on the horizontal axis, where 1 is the charge amount injected for the time Δt for one gradation of pulse width modulation. ing. The vertical axis is the emission current amount IE when there is no voltage drop, and is normalized so that the brightness of each color is 1 when the pulse width is 255 gradations (255 × Δt).

The characteristics of qgb and qr in FIG. 22 are the same as the characteristics of FIG. 20 described above, qgb is the gradation characteristic of green and blue, and qr is the gradation characteristic of red. In FIG. 22, the square area indicated by GA is an area showing the amount of emitted charge versus the brightness when the gain is 1, and the normalized charge amount of 0 to 2 on the horizontal axis.
55 corresponds to 0 to 255 of the image data (corresponding to the case where the above-mentioned overflow processing is not performed).

When the gain is ½, the amount of charge emitted to the phosphor is the amount of charge obtained by multiplying (1/2) the image data, so that the image data 0 to 255 are normalized charges. Corresponds to the quantities 0 to 127. The square area indicated by GB in FIG. 22 is an area showing the amount of emitted charge actually emitted versus the brightness when the gain is ½.

Similarly, when the gain is 1/4, the amount of charge emitted to the phosphor is the amount of charge obtained by multiplying the image data by the gain (1/4), so that the image data 0 to 255 are normalized charge. Corresponds to the quantities 0 to 63. The square region shown by GC in FIG. 22 is a region showing the amount of emitted charge actually emitted versus the brightness when the gain is 1/4.

When the gain is G1, the amount of charge emitted to the phosphor is the amount of charge obtained by multiplying the image data by the gain (G1 times), so that the image data 0 to 255 is the normalized charge amount 0 to (255 × It corresponds to G1). The square region indicated by GG in FIG. 22 is a region showing the amount of emitted charge actually emitted versus the luminance when the gain is G1.

As described above, the amount of emitted charges actually emitted corresponds to the value obtained by multiplying the image data by the gain (operating point determined by the gain).

Therefore, the saturation characteristic of the phosphor can be canceled by converting the gradation of the image data as follows.

When the gain is 1, the normalized charge amounts 0 to 255 correspond to the image data 0 to 255. Therefore, the red phosphor is converted by the γ correction table having the conversion characteristic shown in FIG. The saturation characteristic of can be canceled.

In FIG. 23, QGB is a characteristic curve for canceling the saturation characteristics of the green and blue phosphors (in this example, it is shown as a straight line indicating that the phosphors are not saturated), and QR (× 1) is shown in FIG.
3 is a characteristic curve for canceling the saturation characteristic of the red phosphor indicated by qr.

Similarly, when the gain is ½, the normalized charge amounts 0 to 127 correspond to the image data 0 to 255, so that the γ correction table having the conversion characteristic shown in FIG. 24 is used. , The saturation characteristics of the red phosphor can be canceled.

In FIG. 24, QGB is a characteristic curve for canceling the saturation characteristics of the green and blue phosphors (in this example, it is shown by a straight line that it is not saturated), and QR (× 1/2) is shown in FIG. 3 is a characteristic curve for canceling the saturation characteristic of the red phosphor shown in the GB region of qr.

In the gradation conversion by the image data, 0 to 255 of the image data (input data) is converted to 0 to 2 of the output data on the basis of the case where the image data is not saturated like QGB.
Conversion is performed in the range of 55 (hereinafter, the range will be described with reference to the case where there is no saturation such as QGB).

The output data in the range of 0 to 255 is multiplied by the gain after the influence of the voltage drop is corrected, and the normalized charge amount emitted to the phosphor is in the range of 0 to 127.

In this way, the conversion for canceling the saturation characteristic of the phosphor at the operating point corresponding to the gain is performed.

In other words, the conversion characteristic for canceling the saturation characteristic of the phosphor can be performed by converting 0 to 255 of image data (input data) in the range of 0 to 255 of output data regardless of the gain.

Similarly, when the gain is 1/4, the normalized charge amounts 0 to 63 correspond to the image data 0 to 255. Therefore, the γ correction table having the conversion characteristics shown in FIG. 25 is used. , The saturation characteristics of the red phosphor can be canceled.

In FIG. 25, QGB is a characteristic curve for canceling the saturation characteristics of the green and blue phosphors (in this example, it is shown by a straight line that it is not saturated), and QR (× 1/4) is shown in FIG. 3 is a characteristic curve for canceling out the saturation characteristic of the red phosphor shown in the GC region of qr.

Similarly, when the gain is G1, the normalized charge amount of 0 to (255 × G1) is changed to 0 to 2 of the image data.
Since it corresponds to 55, the image data is multiplied by the gain (G1
Then, conversion is performed by the γ correction table having the characteristics shown by QGR and QR (× 1) in FIG. 23, and the influence of the saturation of the phosphor is corrected. Further, the output converted by the γ correction table is multiplied by 1 / gain (1 / G1) to obtain output data in the range of 0 to 255 for correcting the voltage drop.

It can be said that the above-mentioned characteristics select the gradation conversion characteristics at the operating point determined by the gain.

Due to the characteristics of the gradation converting means 200 described above, even when the overflow processing is performed, the above-described problem of the reddish display can be canceled.

Next, the structure of the actual gradation converting section 200 will be described.

FIG. 26 shows the configuration of the gradation converting section 200. In FIG. 26, 201 and 203 are multipliers, 202 is a γ correction table realized by a memory or the like, and 204 is an inverse calculator. This configuration realizes the functions described above. In FIG. 26, for simplification, the configuration corresponding to one color is shown. As a matter of course, the gradation conversion unit 200 is configured by three sets having the same configuration for each of red, green, and blue. At this time, the contents of the γ correction table correspond to each color according to the saturation characteristics of the phosphor.

The inputted image data is multiplied by the gain (G1) by the multiplier 201. As described above, the γ correction table 202 performs gradation conversion in which the input image data is converted into a gain-multiplied emission charge amount, and the saturation characteristic of the phosphor normalized by the maximum emission charge amount (1 to 255 range) is canceled. To do.

[0289] The γ correction table 202 performs gradation conversion for canceling the saturation characteristic of the phosphor by the amount of emitted charge actually emitted.

If this is the case, since the output of the γ correction table is still multiplied by the gain, the multiplier 203 multiplies the gain by 1 / gain (1 / G1) in order to restore the data for the actual voltage drop correction. The reciprocal unit 204 outputs the reciprocal of the gain.

Since the gain is generally smaller than 1, the image data multiplied by the gain is input to the γ correction table 202. Therefore, the γ correction table 2 is set so that the number of significant digits does not decrease.
It was necessary to make the number of bits of 02 larger than the number of bits of image data.

With the above-described structure, the above-described function can be realized and the above-described problem of the reddish display due to the hardware can be canceled. Furthermore, G = Kg × INMA that satisfies the above-described gain calculation method (Equation 12)
When there is a constant relationship of X / MAXKg ≦ 1, 1 / G =
MAX / (Kg × INMAX). Kg x INMA
Since X is a constant, Kg ′ = 1 / (Kg × INMAX)
And Kg ′ are new constants, 1 / G = Kg ′ × MA
It becomes X.

That is, the reciprocal calculator 2 for obtaining the reciprocal of the gain
04 can be obtained by multiplying the maximum value MAX of the corrected image data by a constant Kg '. This makes it possible to replace the reciprocal unit composed of a ROM or the like with a multiplier and reduce the amount of hardware.

Furthermore, the second gain calculation method (Equation 1)
Similarly for 3), the above-described gain calculation method (Equation 1)
G1 that satisfies 3) = Kg1 × INMAX / AMAXKg
When there is a constant relation of 1 ≦ 1, 1 / G = AMAX /
(Kg1 × INMAX).

Since Kg1 × INMAX is a constant, Kg
If 1 ′ = 1 / (Kg1 × INMAX) and Kg1 ′ are new constants, then 1 / G = Kg1 ′ × AMAX.

That is, the reciprocal calculator 2 for obtaining the reciprocal of the gain
04 can be obtained by multiplying AMAX obtained by smoothing (averaging) the maximum value of the corrected image data detected in the frame before the current frame in the frame direction by a constant Kg1 ′. This makes it possible to replace the reciprocal unit composed of a ROM or the like with a multiplier and reduce the amount of hardware.

Further, the third gain calculating method is a method of obtaining the gain by the expression 12 and further averaging. In this case, the reciprocal unit can be replaced with a multiplier by the same calculation as the second method. However, it is necessary to perform averaging separately for both the gain and the maximum value of the corrected image data. Therefore, the hardware for the averaging process increases, but even if this increase is taken into consideration, the total amount of hardware is smaller than that of the method using the reciprocal unit.

Next, the γ correction table 202 for canceling the saturation of the phosphor may have the following configuration. Assuming that the characteristics of the γ correction table 202 are the required luminance Lr and the amount of charge qr to be injected into the phosphor, the required luminance Lr and the amount of charge q
If both r are normalized, qr = fr (Lr) where fr
(Lr) is a γ correction table 20 for correcting saturation of the phosphor
This is the characteristic stored in 2.

Here, gr (Lr) = Lr-fr (L
The function gr (Lr) that becomes r) is defined. I.e. gr
(Lx) is a function of the difference from the characteristic in which the luminance and the charge amount are proportional. At this time, the relationship of qr = Lr-gr (Lr) is necessary to cancel the saturation of the phosphor.

The γ correction table 20 of the above-described embodiment
2 is a table having the property of gr (Lr), and Lr to g
It may be composed of a subtractor for subtracting the output of the table having the characteristic of r (Lr). At this time, a subtracter is added as a hardware configuration, but when using a table having a characteristic of gr (Lr) in the memories of the same capacity,
There are advantages that the number of gradations increases and the processing accuracy improves.

FIG. 27 shows another embodiment of the gradation converting section. Also in FIG. 27, a configuration corresponding to one color is shown for simplification. As a matter of course, the gradation conversion unit 200 is configured by three sets having the same configuration for each of red, green, and blue. At this time, each content of the γ correction table corresponds to each color according to the saturation characteristic of the phosphor.

In FIG. 27, 202a, 202b, 2
02c is a γ correction table, each of which has a gain of 1
A conversion table is stored for canceling the saturation characteristic of the phosphor corresponding to the amount of emitted charge actually emitted at the times of double, 1/2 and 1/4. Actually, the characteristics are those shown in FIGS. 23, 24, and 25 described above. Reference numeral 205 denotes a linear interpolating means, which inputs the gain G1 to each of the γ correction tables 20.
It is a means for obtaining an interpolation value for the gain G1 by linear interpolation from the outputs of two tables sandwiching the gain G1 of 2a, 202b, 202c.

Since the characteristic for canceling the saturation characteristic of the phosphor, which is determined by the gain, changes monotonically, the characteristic of each of the γ correction tables 202a, 202b, 202c is linearly interpolated by the above-mentioned configuration to obtain a conversion for any gain G1. The characteristics can be obtained.

As a matter of course, increasing the number of γ correction tables improves the accuracy, but increases the hardware cost. γ
When the correction table is 3 or more, it is possible to prevent a clear deterioration of the display quality.

Also with the above configuration, the above-described function can be realized, and the above-mentioned problem of reddish display due to the hardware can be canceled.

Further, in the description of this embodiment, the gradation characteristics of the green and blue phosphors are described as having high linearity and no saturation characteristics, but in reality, they are much smaller than the red phosphor, The brightness has a saturation characteristic that it is saturated with respect to the amount of charge. In this case, the saturation characteristics of the phosphors of the respective colors can be corrected by obtaining the above-mentioned normalized gradation characteristics for each color with less saturation and creating a table for canceling the characteristics. Furthermore, the saturation characteristic of the phosphor changes depending on the acceleration voltage (potential of the high-voltage power supply) between the face plate and the rear plate and the maximum amount of electric charge applied to the phosphor. When the panel is driven, since the driving time of each electron-emitting device is fixed, the maximum amount of charge injected into the phosphor is the emission current IE of the electron-emitting device, that is, the potential (Vs) of the scanning means, the modulation means. Electric potential (Vpw
m). The saturation characteristics of the phosphor are the potential of the high-voltage power supply, the potential of the scanning means (Vs), the potential of the modulation means (Vpw).
It depends on m). This is applicable when the potential of the high-voltage power supply, the potential of the scanning unit (Vs), and the potential of the modulation unit (Vpwm) are varied for initial adjustment to absorb individual differences of the display device or adjustment performed by the user. It is preferable to change to a γ correction table that cancels the saturation characteristic of the phosphor at the potential.

(Shift Register, Latch Circuit) The corrected image data Dlim, which is the output of the limiter circuit, is transferred by the shift register 5 from the serial data format to
The parallel image data ID1 to IDN for each modulation wiring are serial / parallel converted and output to the latch circuit. The latch circuit latches the data from the shift register by the timing signal Dataload immediately before the start of one horizontal period. The output of the latch circuit 6 is supplied to the modulation means as parallel image data D1 to DN.

In this embodiment, the image data ID1 to ID
Each of N and D1 to DN is 8-bit image data. These operation timings are the timing generation circuit 4
Timing control signals TSFT and Da from (FIG. 12)
It operates based on taload.

(Details of Modulating Means) The parallel image data D1 to DN output from the latch circuit 6 are supplied to the modulating means 8.

As shown in FIG. 28A, the modulation means is a pulse width modulation circuit (PWM circuit) provided with a PWM counter, a comparator and a switch (FET in the figure) for each modulation wiring.

The relationship between the image data D1 to DN and the output pulse width of the modulating means has a linear relationship as shown in FIG. 28 (b).

FIG. 3C shows an example of the output waveform of the modulator 3
Show one.

In the figure, the upper waveform is the waveform when the input data to the modulating means is 0, the central waveform is the waveform when the input data to the modulating means is 128, and the lower waveform is the modulating means. It is a waveform when the input data to is 255.

In this example, the input data D to the modulation means is
The number of bits 1 to DN is 8 bits.

In the above description, when the input data of the modulating means is 255, there is a part that the modulated signal having the pulse width corresponding to one horizontal scanning period is output.
More specifically, as shown in FIG. 6C, a very short time is provided before the pulse rises and a slight period after the fall but is not driven to allow a timing margin.

FIG. 29 is a timing chart showing the operation of the modulation means in the embodiment of the present invention.

In the figure, Hsync is a horizontal synchronizing signal, Dataload is a load signal to the latch circuit 6,
D1 to DN are input signals to the columns 1 to N of the aforementioned modulation means,
Pwmstart is a PWM counter synchronization clear signal,
Pwmclk is the clock of the PWM counter. Further, XD1 to XDN represent outputs of the first to Nth columns of the modulation means.

When one horizontal scanning period starts as shown in the figure, the latch circuit 6 latches the image data and transfers the data to the modulating means.

The PWM counter, as shown in FIG.
Counting is started based on Pwmstart and Pwmclk, and when the count value reaches 255, the counter is stopped and the count value 255 is held.

The comparator provided for each column is
The count value of the PWM counter is compared with the image data of each column, and when the value of the PWM counter is greater than or equal to the image data, High
h is output, and Low is output during the other periods.

The output of the comparator is connected to the gates of the switches in each column, and the output of the comparator is Low.
During the period, the switch on the upper side (Vpwm side) in the figure is ON,
The lower (GND side) switch is turned off, and the modulation wiring is connected to the voltage Vpwm.

On the contrary, while the output of the comparator is High, the upper switch in the figure is turned off and the lower switch is turned on, and the voltage of the modulation wiring is connected to the GND potential.

The pulse width modulation signal output from the modulating means is D1 and D in FIG. 29 as a result of the operation of each section as described above.
2, a waveform in which the rising edges of the pulses are synchronized as shown by DN.

(Correction Data Calculation Means) The correction data calculation means is a circuit for calculating the correction data of the voltage drop by the above-mentioned correction data calculation method. The correction data calculation means is composed of two blocks, a discrete correction data calculation unit and a correction data interpolation unit, as shown in FIG.

The discrete correction data calculation unit calculates the voltage drop amount from the input video signal and calculates the correction data discretely from the voltage drop amount. The calculation unit discretely calculates the correction data by introducing the concept of the above-described degenerate model in order to reduce the calculation amount and the hardware amount.

The correction data calculated discretely is interpolated by the correction data interpolation section, and the correction data CD suitable for the size of the image data and its horizontal display position x is calculated.

(Discrete Correction Data Calculation Unit) FIG. 31 shows a discrete correction data calculation unit for discretely calculating correction data according to the embodiment of the present invention.

As will be described below, the discrete correction data calculation unit divides the image data into blocks, calculates a statistic amount (number of lights) for each block, and calculates the voltage drop amount at each node position from the statistic amount. Function as a voltage drop amount calculation unit that calculates changes over time, a function that converts the voltage drop amount for each time into a light emission brightness amount, and a function that integrates the light emission brightness amount in the time direction to calculate a total light emission brightness amount , And the correction data for the reference value of the image data at the discrete reference points.

In the figure, 100a to 100d are lighting number counting means, 101a to 101d are groups of registers for storing the number of lighting at each time for each block, and 10
2 is the CPU, 103 is the parameter aij described in equation 2.
Table memory for storing the calculation result, 104 a temporary register for temporarily storing the calculation result, and 105 a CP
Program memory in which the U program is stored, 1
Reference numeral 11 is a table memory in which conversion data for converting the amount of voltage drop into the amount of emission current is described, and 106 is a group of registers for storing the calculation result of the discrete correction data described above.

Lighting number counting means 100a to 100d
Is composed of a comparator and an adder as shown in FIG. The video signals Ra, Ga, and Ba are input to the comparators 107a to 107c, respectively, and sequentially C
It is compared with the value of val.

Note that Cval corresponds to the image data reference value set for the above-mentioned image data.

The comparators 107a to 107c compare Cval with the image data, and if the image data is larger, Hi.
gh is output, and Low is output if it is small.

The output of the comparator is the adders 108 and 1
09, they are added to each other, and addition is performed for each block by the adder 110, and the addition result for each block is set as the lighting number for each block in the register group 101.
Store in a to c.

The lighting number counting means 100a to 100d respectively have 0, 64 and 1 as the comparison value Cval of the comparator.
28 and 192 are input.

As a result, the lighting number counting means 100a
Counts the number of image data larger than 0 among the image data, and totals each block by the register 101a.
To store.

Similarly, the lighting number counting means 100b counts the number of image data larger than 64 among the image data, and the total for each block is registered in the register 101b.
To store.

Similarly, the lighting number counting means 100c counts the number of image data larger than 128 among the image data, and the total number of each block is registered in the register 101.
Store in c.

Similarly, the lighting number counting means 100d counts the number of image data larger than 192 among the image data, and the total for each block is registered in the register 101.
d Store.

When the number of lights for each block and for each time is counted, the CPU reads the parameter table aij stored in the table memory 103 at any time, and formulas 2-4 are used.
Then, the amount of voltage drop is calculated, and the calculation result is stored in the temporary register 104.

In this example, the CPU is provided with the product-sum operation function for smoothly performing the calculation of the equation 2.

As a means for realizing the operation shown in the equation 2, the product sum operation may not be performed by the CPU, and for example, the calculation result may be stored in the memory.

That is, the number of lighting of each block may be used as an input and the voltage drop amount at each node position may be stored in the memory for all possible input patterns.

When the calculation of the voltage drop amount is completed, C
The PU reads the voltage drop amount for each block from the temporary register 104 at each time, and the table memory 2
With reference to (111), the amount of voltage drop was converted into the amount of emission current, and the discrete correction data was calculated according to equations 6-8.

The calculated discrete correction data is stored in the register group 1
It was stored in 06.

(Correction Data Interpolation Section) The correction data interpolation section is means for calculating correction data corresponding to the position (horizontal position) where the image data is displayed and the size of the image data. This means interpolates the correction data calculated discretely to display the image data (horizontal position).
Also, correction data corresponding to the size of the image data is calculated.

FIG. 32 is a diagram for explaining the correction data interpolation unit.

In the figure, reference numeral 123 is a decoder for determining the node numbers n and n + 1 of the discrete correction data used for interpolation from the display position (horizontal position) x of the image data, and 124 is the size of the image data. It is a decoder for determining k and k + 1 in Expressions 9 to 11.

Further, the selectors 125 to 128 are selectors for selecting the discrete correction data and supplying it to the linear approximation means.

Further, 121 to 123 are expressions 9 to 9 respectively.
It is a linear approximation means for performing the linear approximation of Expression 11.

FIG. 33 shows an example of the structure of the linear approximation means 121. Generally, the linear approximation means can be configured by a subtractor, an integrator, an adder, a divider, etc., as represented by the operators of equations 9 to 11.

However, preferably, the number of column wirings between the nodes for calculating the discrete correction data and the interval of the image data reference value for calculating the discrete correction data (that is, the time interval for calculating the voltage drop) is a power of two. There is a merit that the hardware can be configured very easily if it is configured as follows. If you set them to a power of 2,
In the divider shown in FIG. 3, Xn + 1-Xn becomes a power of 2 and bit shift is required.

If the value of Xn + 1-Xn is always a constant value and a value represented by a power of 2, it is sufficient to shift the addition result of the adder by the multiplier of the power and output the result. There is no need to make a divider.

Further, at other points, the intervals of the nodes for calculating the discrete correction data and the intervals of the image data are set to powers of 2, for example, the decoders 123 to 12 are used.
4 can be easily manufactured, and FIG.
There are many advantages, such as the fact that the operation performed by the subtractor can be replaced with a simple bit operation.

(Operation Timing of Each Part) FIG. 34 shows a timing chart of the operation timing of each part.

In the figure, Hsync is a horizontal synchronizing signal and DotCLK is a PLL in the timing generation circuit.
A clock generated by the circuit from the horizontal synchronizing signal Hsync, R, G, B are digital image data from the input switching circuit, Data is image data after data array conversion,
Dlim is the output of the limiter means, correction image data subjected to voltage drop correction, TSFT is a shift clock for transferring the correction image data Dlim to the shift register 5, and Dataload is for latching data to the latch circuit 6. Load pulse, Pwmstart is an example of the pulse width modulation start signal described above, and modulation signal XD1 is an example of the pulse width modulation signal supplied to the modulation wiring 1.

With the start of one horizontal period, the selector 23
The digital image data RGB is transferred from. In the figure, in the horizontal scanning period I, the input image data is R
Represented by _I, G_I, and B_I, the image data is stored in the data array conversion circuit 9 for one horizontal period, and is output as digital image data Data_I in the horizontal scanning period I + 1 according to the pixel arrangement of the display panel. To be done.

R_I, G_I and B_I are input to the correction data calculating means in the horizontal scanning period I. With this means, the number of times of lighting described above is counted, and at the end of counting, the voltage drop amount is calculated.

Subsequent to the calculation of the voltage drop amount, the discrete correction data is calculated, and the calculation result is stored in the register.

In the scanning period I + 1, in synchronization with the output of the image data Data_I one horizontal scanning period before from the data array conversion unit, the correction data interpolating means interpolates the discrete correction data to calculate the correction data. To be done. The interpolated correction data is supplied to the adder 12.

The adder 12 sequentially adds the image data Data and the correction data CD and transfers the corrected correction image data Dlim to the shift register. The shift register stores the corrected image data Dlim for one horizontal period according to Tsft, performs serial-parallel conversion, and outputs parallel image data ID1 to IDN to the latch circuit 6. The latch circuit 6 is Dataaloa
The parallel image data ID1 to IDN from the shift register are latched according to the rising edge of d, and the latched image data D1 to DN are transferred to the pulse width modulation means 8.

The pulse width modulation means 8 outputs a pulse width modulation signal having a pulse width corresponding to the latched image data. In the image display device of the present embodiment, as a result, the pulse width output by the modulation means is displayed with a delay of two horizontal scanning periods with respect to the input image data.

When an image is displayed by such an image display device, it is possible to correct the amount of voltage drop in the scanning wiring, which has been a problem in the past, and it is possible to improve the deterioration of the displayed image due to it. It was possible to display a very good image.

Further, by introducing some approximations, the correction amount of the image data for correcting the voltage drop can be easily and suitably calculated, and this can be realized by very simple hardware. It had a very good effect.

(Second Embodiment) Corrected image data Dou
t is the result of adding the image data Data and the correction data CD.

If the result of this addition does not fall within the input range of the modulation means, it is feared that the correction will cause overflow and another discomfort in the displayed image.

To deal with such a problem, in the first embodiment, the maximum value of the corrected image data is detected, and the gain is calculated so that the maximum value corresponds to the maximum value of the input range of the modulating means. Then, the gain is multiplied by the corrected image data to prevent overflow.

On the other hand, in the present embodiment, the maximum value of the corrected image data is detected in the same manner, but before the correction is performed so that the maximum value corresponds to the maximum value of the input range of the modulation means. We decided to limit the size of image data.

That is, in order to prevent overflow, the image data input in advance is multiplied by a gain to reduce its amplitude range to prevent overflow.

The overflow processing of this embodiment will be described below with reference to FIG.

In the figure, 22R, 22G and 22B are multipliers, 9 is a data array converter, 5 is a shift register for one line of image data, 6 is a latch circuit for one line of image data, and 8 is a modulation wiring of the display panel. A pulse width modulation means for outputting a modulated signal, 12 an adder, 14 correction data calculation means, 20 a maximum value detection circuit (means) for detecting the maximum value of the corrected image data Dout in the frame, 21
Is a gain calculation unit, and 200 is a gradation conversion unit. Since the gradation conversion unit 200 will be described later, the following description will be made assuming that the gradation conversion unit 200 is not provided.

Also, R, G, B are RGB parallel input video data, Ra, Ga, Ba are RGB parallel video data subjected to inverse γ conversion processing, and Rx, Gx, Bx are multipliers, and gain G2 is The multiplied image data, the gain G2 is the gain calculated by the gain calculation unit, Data is the image data subjected to parallel / serial conversion by the data array conversion unit, CD is the correction data calculated by the correction data calculation means, and Dout is the addition. The corrected image data (corrected image data) and Dlim are added to the image data by the limiter by the limiter.
It is the corrected image data in which ut is limited to the upper limit of the input range of the modulation means or less.

(Multipliers 22R, 22G, 22B) Multipliers 22R, 22G, 22B are image data R after inverse γ conversion.
It is a means for multiplying a, Ga, and Ba by a gain G2.

More specifically, the multiplier multiplies the image data by the gain G2 according to the gain determined by the gain calculating means, and outputs the multiplied image data Rx, Gx, Bx.

The gain G2 is a value calculated by the gain calculating means, and is the corrected image data Dout which is the addition result of the image data Data and the correction data in the adder described later.
Is a value determined so as to fit within the input range of the modulation means.

(Maximum value detecting means 20) Maximum value detecting circuit 2
0 will be described.

The maximum value detecting means in the embodiment of the present invention is connected to each part as shown in FIG.

The maximum value detecting means is means for detecting the maximum value in the corrected image data Dout for one frame.

The same means is a circuit which can be easily constructed by a comparator and a register. The means compares the value stored in the register with the size of the correction image data Dout that is sequentially transferred, and the correction image data Do is compared.
If ut is larger than the register value, the circuit updates the register value with the data value.

If the register value is cleared to 0 at the beginning of the frame, the maximum value MAX of the corrected image data in that frame is stored in the register at the end of the frame.

The maximum value MAX of the corrected image data detected in this way is transferred to the gain calculating means.

(Gain Calculating Means) The gain calculating means is a means for referring to the detected value MAX of the maximum value detecting means and calculating the gain so that the corrected image data Dout falls within the input range of the modulating means. Also in this embodiment, the gain calculation means calculates the gain for adjusting the amplitude of the corrected image data based on the adaptive gain method.

On the other hand, in preventing the overflow of the corrected image data in the configuration of this embodiment (FIG. 35),
The gain may be calculated by the fixed gain method.

The gain determination method is as follows: MAX is the maximum value of the corrected image data Dout in one frame, INMAX is the maximum value of the input range of the modulator, and GB is the gain G2 calculated by the gain calculator for the previous frame. Then,

[Equation 16] It may be determined so that

In this gain calculating means, the gain is updated in the vertical blanking period to change the gain value for each frame.

In the configuration of the image display apparatus according to the embodiment of the present invention, the maximum value of the corrected image data of the previous frame is used to calculate the gain by which the corrected image data of the current frame is multiplied. Has become.

That is, overflow is prevented by utilizing the correlation of corrected image data (image data) between frames.

Therefore, strictly speaking, overflow may occur due to the difference in the corrected image data for each frame.

To address such a problem, a limiter means is provided for the output of the multiplier that multiplies the corrected image data and the gain, and the circuit is designed so that the output of the multiplier always falls within the input range of the modulating means. It was even better.

Further, the present inventors have confirmed that, in addition to the above-described gain determination method, the gain may be calculated by the following other method.

That is, as the gain to be applied to the corrected image data of the current frame, the maximum values of the corrected image data detected in the frames before the current frame are averaged, and the average value AMAX is

[Equation 17] It may be determined so that

However, GB is the gain G2 calculated by the gain calculating means for the previous frame.

As another method, the current gain may be calculated by calculating the gain G2 for each frame by the equation 14 and averaging the gains.

The inventors have confirmed that any of these three methods is preferable in terms of preventing overflow, but considering that flicker occurs as described in the first embodiment. If so, it is preferable to calculate by the method of Expression 15.

The inventors have examined the number of frames for averaging the maximum value of the corrected image data in the gain calculation method of the equation 15.
When the maximum values of the corrected image data from 6 to 64 frames before were averaged, it was preferable.

In this method, more preferably, as shown in FIG.
It goes without saying that it is preferable to provide a limiter for limiting the output of the adder to completely prevent the overflow, as shown in FIG.

Further, the method of calculating the gain may be changed by detecting the scene change as in the first embodiment.

(Gradation Converting Means) In the second embodiment, the same phenomenon as in the first embodiment was confirmed when the gradation converting section 200 was not provided.

The second embodiment is different from the first embodiment only in the place to multiply the gain in the overflow processing.
The gradation conversion unit 200 having the same configuration as that of the above embodiment is provided.
The characteristics and configuration of the gradation conversion unit are the same as those in the first embodiment shown in FIG.
6 or FIG. 27, FIG. 21, FIG. 23, FIG. 24, FIG.
5 is the characteristic. With this configuration, it is possible to cancel the influence of the saturation of the phosphor, and it is possible to cancel the above-described problem of the reddish display. Gradation conversion means 20
When the configuration of 0 is the configuration shown in FIG. 26, as shown in the first embodiment, a table having a characteristic of gr (Lr) which is a function of a difference from the characteristic in which the luminance and the charge amount are proportional, and Lr To a gr (Lr) table output may be subtracted.

Further, in the second embodiment, the gradation conversion means 20
When the configuration of 0 is the configuration shown in FIG. 26, the multiplier 22 of FIG.
R, 22G, 22B, multiplier 203 of FIG. 26, and reciprocal calculator 2
04 can be omitted. Because the multiplier 20
3 is multiplied by 1 / gain by the multiplier 203 and further multiplied by gain by the multipliers 22R, 22G, and 22B. Therefore, the data input to the multiplier 203 and the multipliers 22R, 22G, and 22B are multiplied. This is because the output data will be the same.

The structure at this time is shown in FIGS. Since the configuration and operation are the same, the description is omitted.

Further, similar to the first embodiment, in the second embodiment as well, the gradation characteristics of the green and blue phosphors are described as having high linearity and no saturation characteristics. Although it is much smaller than the phosphor, the brightness has a saturation characteristic that it is saturated with respect to the charge amount. In this case, the saturation characteristics of the phosphors of the respective colors can be corrected by obtaining the above-mentioned normalized gradation characteristics for each color with less saturation and creating a table for canceling the characteristics.

In consideration of the characteristics of the inverse γ processing section 17,
It is also possible to reduce the amount of hardware by determining the characteristics of the γ tables 202a, 202b and 202c in FIG. 27 and deleting the inverse γ processing unit 17. As shown in the first embodiment, the saturation characteristic of the phosphor changes depending on the acceleration voltage (potential of the high-voltage power supply) between the face plate and the rear plate and the maximum amount of charge applied to the phosphor. When the panel is driven, since the driving time of each electron-emitting device is fixed, the maximum charge amount injected into the phosphor is the emission current IE of the electron-emitting device, that is, the potential (Vs) of the scanning means,
It depends on the potential (Vpwm) of the modulation means.

The saturation characteristics of the phosphor are as follows:
Potential of scanning means (Vs), potential of modulation means (Vpwm)
It changes with. The potential of the high-voltage power supply, the potential of the scanning unit (Vs), the potential of the modulation unit (Vp) are adjusted for initial adjustment to absorb individual differences of the display device and adjustment performed by the user.
When changing wm), it is preferable to change to a γ correction table that cancels the saturation characteristics of the phosphor at the corresponding potential.

Further, in the image display device according to the embodiment of the present invention, when non-zero, uniform image data of the same color is input, the output terminal of the scanning means is processed by the process of canceling the influence of the voltage drop. It is driven so that the pulse width of the pulse output from the near modulation means is shorter than the pulse width of the pulse output from the modulation means far from the output terminal of the scanning means.

Furthermore, as a result of canceling the saturation characteristic of the phosphor depending on the amount of emitted charge of the electron-emitting device, the luminance balance of the displayed colors does not shift even if any uniform image data of the same color is obtained. In other words, the color temperature of white is driven almost uniformly.

Further, in the embodiment of the present invention, an example of correcting the saturation characteristic of the phosphor is shown. However, with the same configuration as the embodiment of the present invention, deterioration of the drive voltage waveform of the electron-emitting device (waveform) It is also possible to correct the fact that the amount of electron emission is different and the gradation characteristic is changed due to the influence of (blurring) or the like.

[0407]

As described above, according to the image display device of the present invention, it is possible to suitably improve the deterioration of the display image due to the voltage drop on the scanning wiring, which has been a problem in the past.

Further, by introducing some approximations, the corrected image data in which the influence of the voltage drop is corrected can be easily and suitably calculated, and it can be realized by very simple hardware. It had a very good effect.

Furthermore, an overflow processing circuit is provided to prevent the corrected image data from overflowing the input range of the modulator, and the overflow can be prevented by the gain.

By constructing the gradation conversion unit for changing the gradation conversion characteristic by the gain in the preceding stage of the structure for correcting the influence of the voltage drop, the saturation characteristic of the phosphor can be canceled out, whereby the high quality can be obtained. I was able to display the image on.

[Brief description of drawings]

FIG. 1 is a diagram showing an overview of an image display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an electrical connection of a display panel.

FIG. 3 is a diagram showing characteristics of a surface conduction electron-emitting device.

FIG. 4 is a diagram showing a driving method of a display panel.

FIG. 5 is a diagram illustrating a degenerate model.

FIG. 6 is a graph showing a voltage drop amount calculated discretely.

FIG. 7 is a graph showing the amount of change in emission current calculated discretely.

FIG. 8 is a diagram for explaining another method of calculating correction data.

FIG. 9 is a diagram illustrating an example of calculation of correction data when the size of image data is 128.

FIG. 10 is a diagram showing an example of calculation of correction data when the size of image data is 192.

FIG. 11 is a diagram for explaining an interpolation method of correction data.

FIG. 12 is a block diagram showing a schematic configuration of an image display device including a gradation conversion unit according to the first embodiment.

FIG. 13 is a block diagram showing a configuration of a scanning circuit of the image display device.

FIG. 14 is a block diagram showing a configuration of an inverse γ processing unit of the image display device.

FIG. 15 is a block diagram showing a configuration of a data array conversion unit of the image display device.

FIG. 16 is a diagram showing an example of consecutive frames.

FIG. 17 is a graph showing the size of image data in consecutive frames.

FIG. 18 is a graph showing gains in consecutive frames.

FIG. 19 is a diagram showing gradation characteristics when the voltage conversion is not corrected and the gradation conversion unit is not provided.

FIG. 20 is a diagram showing characteristics of charge amount vs. luminance.

FIG. 21 is a diagram showing a characteristic of canceling saturation of a phosphor when overflow processing is not performed.

FIG. 22 is a diagram showing a relationship between a charge amount-luminance characteristic and a gain.

FIG. 23 is a diagram showing a characteristic of canceling saturation of a phosphor when the gain is 1.

FIG. 24 is a diagram showing a characteristic of canceling saturation of a phosphor when the gain is ½.

FIG. 25 is a diagram showing a characteristic of canceling saturation of a phosphor when a gain is 1/4.

FIG. 26 is a block diagram showing a configuration example 1 of a gradation conversion unit.

FIG. 27 is a block diagram showing a configuration example 2 of a gradation converting unit.

FIG. 28 is a diagram illustrating the configuration and operation of the modulation means of the image display device.

FIG. 29 is a timing chart of the modulation means of the image display device.

FIG. 30 is a block diagram showing a configuration of a correction data calculation unit of the image display device.

FIG. 31 is a block diagram showing a configuration of a discrete correction data calculation unit of the image display device.

FIG. 32 is a block diagram showing a configuration of a correction data interpolation unit.

FIG. 33 is a block diagram showing a configuration of a linear approximation means.

FIG. 34 is a timing chart of the image display device.

FIG. 35 is a block diagram showing a schematic configuration of an image display device of a second embodiment.

FIG. 36 is a block diagram showing a configuration of an image display device according to a second embodiment with reduced hardware.

FIG. 37 is a block diagram showing a configuration example of a gradation conversion unit with a reduced amount of hardware according to the second embodiment.

FIG. 38 is a block diagram showing a configuration of a conventional image display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 display panel 2 scanning circuit 8 pulse width modulation means 12 adder 14 correction data calculation means 17 inverse γ processing section 19 delay circuit 20 maximum value detection means 21 gain calculation means 22, 22R, 22G, 22B multiplier 23 selectors 100a, 100b , 100c, 100d Lighting number counting means 101a, 101b, 101c, 101d Register group 103 Table memory 111 Table memory 107a, 107b, 107c Comparator 123, 124 Decoder 200 Gradation converter 201, 203 Multipliers 202, 202a, 202b, 202c γ correction table 204 Inverse calculator 205 Linear interpolator 1001 Substrate 1002 Cold cathode device 1003 Row wiring (scanning wiring) 1004 Column wiring (modulation wiring) 1007 Face plate 1008 Fluorescent film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 G09G 3/20 641C 641P 641Q 642 642A 642J 642P H04N 5/66 H04N 5/66 A (72) Inventor Osamu Sagano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Takeshi Ikeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 5C058 AA03 AA12 BA07 BB03 BB14 5C080 AA18 BB05 CC03 DD01 DD05 DD22 EE19 EE29 EE30 FF12 GG09 GG12 GG15 GG17 JJ02 JJ04 JJ05 JJ06

Claims (19)

[Claims] 1. A plurality of image forming elements connected to each of a plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, and a modulation means connected to the column wirings. A gradation conversion means for converting the gradation characteristics of the input image data, and an image in which the output of the gradation conversion means is corrected for the influence of the voltage drop caused by the resistance of the row wiring and the scanning means. An image display device comprising: a corrected image data calculation unit that calculates corrected image data, which is data, and a modulation unit that receives the corrected image data as an input and outputs a modulation signal to the column wiring. An image display device characterized in that the conversion characteristic corrects the light emission characteristic of the image forming element when there is no voltage drop. 2. A plurality of image forming elements connected to each of a plurality of row wirings and column wirings and arranged in a matrix, a scanning means connected to the row wirings, and a modulation means connected to the column wirings. A gradation conversion means for converting the gradation characteristics of the input image data, and an image in which the output of the gradation conversion means is corrected for the influence of the voltage drop caused by the resistance of the row wiring and the scanning means. It has a correction image data calculation means for calculating correction image data, which is data, and a function for multiplying a coefficient for adjusting the amplitude of the correction image data so that the amplitude of the correction image data corresponds to the input range of the modulation means. An image display device comprising: an amplitude adjusting unit, wherein the gradation converting unit has a gradation converting characteristic corresponding to the coefficient, and the modulating unit includes an amplitude adjusting unit. An image display device, wherein the corrected image data whose amplitude has been adjusted is input, and a modulation signal is output to the column wiring. 3. The image forming device is an electron emitting device,
An image display device that emits light when electrons emitted from the electron-emitting device collide with a phosphor, wherein the gradation conversion unit cancels a saturation characteristic of the phosphor at an operating point determined by the coefficient. The image display device according to claim 2, further comprising a function of changing a gradation conversion characteristic according to the coefficient. 4. The gradation conversion means comprises a multiplier for multiplying the image data by the coefficient and a gamma correction table for canceling the saturation characteristic of the phosphor when there is no voltage drop, and the output of the multiplier is obtained. 4. The image display device according to claim 3, wherein the gamma correction table that cancels the gradation characteristic of luminance when there is no voltage drop is input. 5. The gradation conversion means is determined by a coefficient and a gamma correction table for canceling the saturation characteristic of the phosphor when there is no voltage drop, the gamma correction table for canceling the gradation characteristic of the luminance in the range determined by the coefficient. The image display device according to claim 3, wherein the output of each gamma correction table is interpolated and output. 6. The image display device according to claim 3, wherein the characteristic of the gradation converting means is a characteristic of canceling a larger saturation of the phosphor when the coefficient is larger than when the coefficient is small. 7. The amplitude adjusting means multiplies the corrected image data calculating means by multiplying the input image data before correction, which is an input to the corrected image data calculating means, by a coefficient for adjusting the amplitude thereof. The image display device according to claim 2, wherein the amplitude of the corrected image data output from the image display device is adjusted. 8. The amplitude adjusting means detects the maximum value of the output of the corrected image data calculating means for each frame, and the coefficient is adaptively adjusted so that the maximum value corresponds to the upper limit of the input range of the modulating means. The image display device according to claim 2, wherein 9. The coefficient is a coefficient determined in advance so that the output of the corrected image data calculating means does not overflow the input range of the modulating means when the input image data is maximum. 2. The image display device according to item 2. 10. The corrected image data calculating means predicts and calculates a spatial distribution and a temporal change of a voltage drop amount that should occur on a row wiring during one horizontal scanning period in response to input image data. The image display device according to claim 2, further comprising: a unit that calculates corrected image data obtained by correcting the input image data from the calculated voltage drop amount. 11. The corrected image data calculating means discretely predicts and calculates a spatial distribution of a voltage drop amount and a temporal change, which should occur on a row wiring during one horizontal scanning period, corresponding to input image data. 3. The image display device according to claim 2, further comprising: means for calculating the corrected image data obtained by correcting the input image data from the calculated voltage drop amount. 12. The corrected image data calculation means discretely predicts and calculates, in the spatial direction and the time direction, the amount of voltage drop that should occur on the row wiring during one horizontal scanning period, corresponding to the input image data. And discrete correction image data calculation means for discretely calculating, from the voltage drop amount, correction image data for image data corresponding to the time when the voltage drop amount is calculated at the spatial position where the voltage drop amount is calculated. And a corrected image data interpolating means for interpolating the output of the discrete corrected image data calculating means and calculating corrected image data corresponding to the size of the input image data and the horizontal display position. The image display device according to. 13. The modulation means is pulse width modulation means for performing modulation by varying the pulse width of a voltage pulse waveform applied to each column wiring in accordance with an input to the modulation means. The image display device according to claim 2. 14. The function of the gradation conversion means for converting the input image data into an emission charge amount required value for canceling the saturation characteristic of the phosphor and outputting the same, and the corrected image data calculation means outputs the output of the gradation conversion means. The image display device according to claim 2, further comprising a function of correcting a variation in the amount of emitted charges due to the influence of the voltage drop with respect to the required amount of emitted charges. 15. The correction image data calculated by the correction image data calculating means is such that the emission charge amount required value is an emission charge amount when there is no voltage drop amount to be generated on the row wiring. The image display device according to claim 2, wherein the image display device is adjusted. 16. One for each of a plurality of row wirings and column wirings.
A plurality of electron-emitting devices connected in a row and arranged in a matrix, a scanning unit connected to the row wirings, a modulation unit connected to the column wirings, and a floor for converting the gradation of input image data. Tone conversion means, and corrected image data calculation means for calculating corrected image data, which is image data in which the influence of the voltage drop caused by the resistance of the row wiring and the scanning means is corrected with respect to the output of the gradation conversion means. And an amplitude adjusting unit having a function of multiplying a coefficient for adjusting the amplitude of the corrected image data so that the amplitude of the corrected image data corresponds to the input range of the modulation unit, and the gradation conversion unit, An image display device having gradation conversion characteristics corresponding to the coefficients, wherein the modulation means inputs a corrected image data whose amplitude is adjusted, and outputs a modulation signal to the column wiring. When the uniform image data of the same color is input, the pulse width of the pulse output from the modulation unit close to the output terminal of the scanning unit is the pulse width of the pulse output from the modulation unit far from the output terminal of the scanning unit. The width is shorter than the width, and as a result of canceling the saturation characteristic of the phosphor that depends on the amount of emitted charge of the electron-emitting device, even if any image data of the same color is displayed regardless of the emission brightness. An image display device characterized in that the color temperature of white is driven substantially uniformly. 17. One for each of a plurality of row wirings and column wirings.
A plurality of electron-emitting devices connected one by one and arranged in a matrix, scanning means connected to the row wirings, modulation means connected to the column wirings, and fluorescent light arranged to face the electron-emitting devices. An image display method using an image display device including a body, the step of calculating an emission charge amount required value in which the emission characteristics of the phosphor with respect to the emission charge amount are corrected according to the image data that is the luminance required value, A step of calculating corrected image data in which a variation in the amount of emitted charge due to an influence of a voltage drop caused by a resistance component of the row wiring and the scanning unit is calculated according to the calculated required value of the emitted charge. The image display method, wherein the modulating means applies a pulse waveform corresponding to the calculated corrected image data to the column wiring. 18. One for each of a plurality of row wirings and column wirings.
An image display method using an image display device comprising a plurality of electron-emitting devices connected in a row and arranged in a matrix, a scanning unit connected to the row wiring, and a modulation unit connected to the column wiring, A step of performing gradation conversion for canceling the light emission characteristic of the electron-emitting device when there is no voltage drop generated by the resistance of the row wiring and the scanning means for the inputted image data; and a gradation for canceling the light emission characteristic. A step of correcting an influence of a voltage drop caused by a resistance component of the row wiring and the scanning means with respect to an output of the step of performing the conversion, wherein the modulating means includes a step of correcting the influence of the voltage drop. Image display method characterized by applying a pulse waveform to the column wiring according to an output 19. One for each of a plurality of row wirings and column wirings.
An image display method using an image display device comprising a plurality of electron-emitting devices connected in a row and arranged in a matrix, a scanning unit connected to the row wiring, and a modulation unit connected to the column wiring, A step of converting the gradation characteristics of the input image data, and a step of correcting the output of the step of converting the gradation characteristics for the influence of the voltage drop caused by the resistance of the row wiring and the scanning means. The image display method is characterized in that the modulation means applies a pulse waveform to the column wiring in accordance with the output of the step of correcting the influence of the voltage drop, wherein the influence of the voltage drop is corrected. The step further includes the step of adjusting the amplitude so that the output of the step of correcting the influence of the voltage drop is in the input range of the modulation means, and the step of converting the gradation characteristic is performed by the input of the modulation means. Depending on the output of the step of adjusting to correspond to the range, a part of the characteristics for canceling the light emission characteristics of the electron-emitting device in the case where there is no voltage drop caused by the resistance of the row wiring and the scanning means is selected. An image display method characterized by: