JPH08272334A - Image display device - Google Patents

Abstract

PURPOSE: To perform a multi-level display with less gradation signals by converting an image data signal into the combination different in a first period and a second period and also similarly making an original gradation voltage into the combination different in both periods. CONSTITUTION: The image data signal is converted into the combination different in the first period and the second period by a data signal conversion circuit 5 to be converted to parallel signals by a series-parallel conversion circuit 1. Switch control signals according to the parallel signals are generated by decoding circuits 2..., and one among switches 3... is turned on. The inputted gradation signals are switched and outputted according to the combination with the original gradation voltage different in the first period and the second period to be imparted from the turned-on switch 3 to a data signal line 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device which performs multi-gradation display using digital image signals.

[0002]

2. Description of the Related Art A matrix type image display device includes a display panel 21 as shown in FIG. A large number of data signal lines 22 ... And a large number of scanning signal lines 23 ... Are arranged on the display panel 21 so as to intersect with each other, and pixels (not shown) are provided at the intersections. Then, the data signal line 22
Are driven by the data signal line drive circuit 24, and the scanning signal lines 23 ... Are driven by the scanning signal line drive circuit 25. With such a configuration, a signal is given to the pixel to perform display.

Generally, the data signal line drive circuit 24 includes one that operates based on an analog image signal and one that operates based on a digital image signal. The latter circuit is disclosed in, for example, JP-A-63-161495 and JP-A-64-10298.

In the configuration disclosed in Japanese Patent Application Laid-Open No. 63-161495 (hereinafter referred to as the first configuration), FIG.
As shown in, the input serial image data signal is converted in parallel by the serial-parallel conversion circuit 31 based on the control signal. The parallel signals are decoded by the decoding circuit 32 ...
Is converted into a signal according to the gradation by the plurality of data signal lines 3
One of the switches 34 connected to 3 is turned on. As a result, the selected gradation signal is turned on.
The data signal line 35 is supplied through the one switch 34.

On the other hand, in the configuration disclosed in Japanese Patent Laid-Open No. 64-10298 (hereinafter referred to as the second configuration),
As shown in FIG. 10, the serial image data signals are
It is converted into parallel by the parallel conversion circuit 41 and input to the pulse width modulation circuit 42. In the pulse width modulation circuit 42,
As shown in FIG. 11, modulation signals D _{0 to} D ₇ having pulse widths corresponding to the parallel signals are generated based on the control clock signal. Then, the switch 43, the signal D ₀ to D ₇
ON / OFF is controlled by each of the above.

As the gradation signal, a step wave as shown in FIG. 11 or a ramp wave whose voltage continuously changes is used. As a result, the gradation of the signal output to the data signal lines 44 ... Is controlled according to the timing when the switches 43 ... Are turned off, that is, according to the image signal from the serial-parallel conversion circuit 41.

[0007]

When the image signal is i bits and the number of data signal lines is j, in the data signal line drive circuit as described above, the signal of i * j bits is serial-parallel converted. Will be done. Further, in the above-described first configuration, 2 ⁱ * j switches 34 ... And 2 ⁱ gray scale signal lines 33 ... Are required. Therefore, in the first configuration, the circuit scale becomes large according to the number of gradations. On the other hand, in the above second configuration, one horizontal scanning period is set to H
Then, the set time per gradation becomes H / 2 ⁱ or less. Therefore, when the number of gradations increases, the switch 43 is required to have high speed.

For the above reasons, it has been difficult to increase the number of display gradations in a drive circuit which operates by a digital image signal.

Therefore, as a technique for solving such a problem, Japanese Patent Laid-Open No. 182695/1988 (hereinafter referred to as a third configuration) and Japanese Patent Laid-Open No. 5-66738 / 1993 (hereinafter
(Referred to as a fourth configuration), it is proposed to perform multi-gradation display by combining gradation signals applied to pixels in the first vertical scanning interval and the second vertical scanning period. Has been done.

In the above-mentioned third configuration, as shown in Table 1, in the first vertical scanning period, the gradation is selected by the signal of the upper i−1 bits of the i-bit image signal, and the second vertical is selected. In the scanning period, the gradation is selected by the signal obtained by adding the signal of the least significant bit to the signal of the most significant i−1 bits of the i-bit image signal. According to this configuration, the potential difference between the gradation signals applied in each vertical scanning period is small, and flicker is not noticeable, but the number of displayable gradations is at most about twice.

[0011]

[Table 1]

On the other hand, in the above-mentioned fourth structure, as shown in Table 2, the signal applied to the gradation signal line is switched between the first vertical scanning period and the second vertical scanning period. Further, the gray scale signals output in the first vertical scanning period and the second vertical scanning period are selected according to a predetermined table.

[0013]

[Table 2]

According to this structure, the data signal line drive circuit for i / 2 bits can be used for the i-bit image signal. For example, the n kinds of gradation signals output from the driving circuit in the first vertical scanning period are a (1) to a (n),
If the n kinds of gradation signals output from the drive circuit in the second vertical scanning period are b (1) to b (n), a maximum of n ² kinds of gradation signals can be obtained by combining the gradation signals output in each vertical scanning period. It enables gradation display.

However, in this case, a (1) and b (1)
The lowest gradation is displayed in combination with and a (n) and b
The highest gradation will be displayed in combination with (n). Therefore, the combination of a (1) and b (n) or a
In the case of the combination of (n) and b (1), the difference between the effective values of the signals applied to the pixels in each vertical scanning period is at least the difference between the minimum value and the maximum value of the gradation voltage.

As described above, in the fourth structure, since there is a large difference in the applied voltage for each vertical scanning period, there is a display problem such as flicker.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an image display device having good visual characteristics and capable of multi-gradation display with a simple structure. .

[0018]

In order to solve the above problems, the image display device of the present invention is characterized in that it is constructed as described in each of the above claims.

An image display device according to a first aspect of the present invention is a digital / analog which supplies one of gradation signals representing n kinds of gradations to a pixel based on an input digital display data signal. The conversion means and n out of m kinds of original gradation voltages where n <m are effective voltages of n kinds of gradation signals.
It is set by a one-to-one correspondence with the original gray-scale voltage of the kind and given to the digital / analog conversion means, and the correspondence is set to the first
And a second combination of gradation voltage setting means, and the i-th image data signal of the p types of image data signals where n <m <p,
Is converted into the j-th display data signal of 1 ≦ j ≦ n, while the second combination is converted into the k-th display data signal of 1 ≦ k ≦ n and j−1 ≦ k ≦ j + 1. Data conversion means for converting the display data signal to be given to the digital / analog conversion means and for making the combination of j and k for i one to one, and providing the gradation signal of the gray scale signal when the same pixel is scanned. The combination of the effective voltage and the original gradation voltage is set to be 1: 1 depending on whether the combination is the first combination or the second combination.

An image display device according to a second aspect of the present invention is the image display device according to the first aspect, wherein the gradation voltage setting means is further configured as follows. That is, the gradation voltage setting means sets m = (3n-1) / 2 when n is an odd number and m = when n is an even number.
While 3n / 2, the combination of the effective voltage a (x) of the x-th gradation signal and the corresponding y-th original gradation voltage b (y) satisfying 1 ≦ x ≦ n is In the case of the combination of 1, when x is an odd number, y = (3x-1) / 2,
While it is determined by the relation that y = 3x / 2−1 when x is an even number, in the case of the above second combination, y = (3x−1) / 2 when x is an odd number, and x is an even number. Sometimes it is decided by the relation that y = 3x / 2.

An image display device according to a third aspect of the present invention is a digital / analog device which supplies one of gradation signals representing n kinds of gradations to a pixel based on an input digital display data signal. The conversion means and n out of m kinds of original gradation voltages where n <m are effective voltages of n kinds of gradation signals.
The gradation voltage setting means for setting a one-to-one correspondence with the original gradation voltages of the types, and the i-th image data signal of the p types of image data signals where n <m <p are set in the first period. 1 ≦
While converting to the j-th display data signal of j ≦ n, it is converted to the k-th display data signal of 1 ≦ k ≦ n and j ≦ k ≦ j + 2 in the second period and given to the digital / analog conversion means. , I and a data conversion means for making the combination of j and k for i to be one-to-one, and the combination of the image data signal and the display data signal when the same pixel is scanned is the first period and the first period. It is set to be 1: 1 in the period of 2.

According to a fourth aspect of the present invention, in the image display apparatus according to the third aspect, the gradation voltage setting means is further configured as follows. That is, the gradation voltage setting means sets m = (3n-1) / 2 when n is an odd number and m = when n is an even number.
3n / 2-1 while a combination of the effective voltage a (x) of the x-th gradation signal satisfying 1 ≦ x ≦ n and the corresponding y-th original gradation voltage b (y), When x is an odd number, y =
(3x-1) / 2, and when x is an even number, y = 3x / 2
It is decided by the relation of -1.

An image display device according to a fifth aspect of the present invention is the image display device according to any one of the first to fourth aspects, wherein the gradation voltage setting means is further configured as follows. ing. That is, the gradation voltage setting means has the same polarity in the first vertical scanning period and the second vertical scanning period and the same polarity in the third vertical scanning period and the fourth vertical scanning period when the same pixel is scanned. While being polar, first
The effective voltage of the grayscale signal is set so that the vertical scanning period and the third vertical scanning period have the same magnitude and different polarities, and the second vertical scanning period and the fourth vertical scanning period have the same magnitude and different polarities. .

An image display device according to a sixth aspect of the present invention is the image display device according to any one of the first to fourth aspects, wherein the gradation voltage setting means is further configured as follows. ing. That is, the gradation voltage setting means has the same polarity in the first vertical scanning period and the third vertical scanning period and the same polarity in the second vertical scanning period and the fourth vertical scanning period when the same pixel is scanned. While being polar, first
The effective voltage of the grayscale signal is set so that the vertical scanning period and the second vertical scanning period have the same magnitude and different polarities, and the third vertical scanning period and the fourth vertical scanning period have the same magnitude and different polarities. .

An image display device according to a seventh aspect of the present invention is the image display device according to any one of the first to sixth aspects, wherein the gradation voltage setting means further comprises a drive voltage of a display element. The original gradation voltage is set to a value obtained by evenly dividing the dynamic range of.

An image display device according to claim 8 of the present invention is the image display device according to any one of claims 1 to 6, wherein the gradation voltage setting means further comprises: , The original gradation voltage is set to a value obtained by evenly dividing the dynamic range of transmittance or reflectance.

An image display device according to a ninth aspect of the present invention is the image display device according to any one of the first to sixth aspects, wherein the gradation voltage setting means further comprises a drive voltage of a display element. Of the first voltage, which is set by equally dividing the dynamic range of the display element, and the second voltage, which is set by equally dividing the dynamic range of the light emission intensity, the transmittance, or the reflectance of the display element. The original gradation voltage is set.

[0028]

In the image display device according to the first aspect, the gradation voltage setting means switches the corresponding combination of the effective voltage of the gradation signal and the original gradation voltage in two ways. On the other hand, by the data conversion means, the i-th image data signal is the j-th display data satisfying 1 ≦ j ≦ n when the corresponding combination of the effective voltage of the gradation signal and the original gradation voltage is the first combination. When the above correspondence is the second combination, it is converted into a k-th display data signal satisfying 1 ≦ k ≦ n and j−1 ≦ k ≦ j + 1. Based on the display data signal, the digital / analog conversion means selects one from the gradation signal of the first combination and the gradation signal of the second combination, and supplies it to the pixel.

As described above, according to the image display device of the first aspect, the combination of the gradation signals applied to the pixels in the first combination and the second combination makes it possible to express with a small number of gradation signals. The number of possible gradations can be increased. Further, when the image data signal of the pixel is constant, by limiting the combination of the gradation signals given to the pixel by the first combination and the second combination, the effect of the gradation signal output in each combination is limited. The voltage difference becomes smaller. Therefore, it is possible to reduce the difference between the effective voltages of the gradation signals applied to the pixels for each vertical scanning period, and it is possible to suppress flicker to a small level.

Particularly, in the image display device according to the second aspect, the combination of the effective voltage a (x) of the xth gradation signal and the corresponding yth original gradation voltage b (y) is In the case of the first combination, y = (3x-1) / when x is an odd number.
2 and y = 3x / 2−1 when x is an even number, while x is an odd number when the combination of the effective voltage a (x) and the original gradation voltage b (y) is the second combination. When y = (3
x−1) / 2, and when x is an even number, y = 3x / 2 is set, so that the grayscale signals applied in the first combination period and the second combination period are All combinations of effective voltages can be different.

In the image display device according to claim 3, the data conversion means converts the i-th image data signal into the j-th display data signal satisfying 1 ≦ j ≦ n in the first period, 1 ≦ k ≦ n and j ≦ k ≦ j in the second period
It is converted to the k-th display data signal of +2. Then, the digital / analog conversion means selects one of the gradation signals set by the gradation voltage setting means from the first period and the second period on the basis of the display data signal, and supplies the selected one to the pixel. To be

As described above, according to the image display device of the third aspect, it is possible to express with a small number of gradation signals by the combination of the gradation signals applied to the pixels in the first period and the second period. The number of gradations can be increased. Also,
When the image data signal of the pixel is constant, by limiting the combination of the gradation signals applied to the pixel in the first period and the second period, the effective voltage of the gradation signal output in each period is reduced. The difference becomes smaller. Therefore, it is possible to reduce the difference between the effective voltages of the gradation signals applied to the pixels for each vertical scanning period, and it is possible to suppress flicker to a small level.

Particularly, in the image display device according to the fourth aspect, the combination of the effective voltage a (x) of the xth gradation signal and the corresponding yth original gradation voltage b (y) is: When x is an odd number, y = (3x-1) / 2 is set, and when x is an even number, y = 3x / 2-1 is set. Therefore, application is performed in the first period and the second period, respectively. The combinations of effective voltages of the generated gradation signals can all be different.

Further, in the image display device according to the fifth aspect, the gradation voltage setting means makes the polarities of the first and second vertical scanning periods the same, and makes the polarities of the third and fourth vertical scanning periods the same. On the other hand, the effective voltage of the gradation signal is set such that the magnitudes of the first and third vertical scanning periods are equal to each other and their polarities are different, and the same applies to the second and fourth vertical scanning periods. As a result, the present invention can be applied to an image display device using a display element that needs to be driven by an AC signal such as liquid crystal.

Further, in the image display device according to the sixth aspect, the gradation voltage setting means sets the polarities of the first and third vertical scanning periods to be the same, and the polarities of the second and fourth vertical scanning periods are also the same. On the other hand, the effective voltage of the gradation signal is set such that the effective voltages in the first and second vertical scanning periods are equal to each other and their polarities are different, and the same is true in the third and fourth vertical scanning periods. As a result, the present invention can be applied to an image display device using a display element that needs to be driven by an AC signal such as liquid crystal.

Further, in the image display device according to any one of claims 7 to 9, the gradation voltage setting means is, as described above, the drive voltage, the transmittance or the like or the drive voltage and the transmission voltage depending on the characteristics of the display element. By setting the original gradation voltage based on the combination of the ratios and the like, the change in the transmittance and the like between the gradations can be made constant, and the display gradation can be smoothly changed.

[0037]

【Example】

[Embodiment 1] An embodiment of the present invention will be described with reference to FIGS.
The explanation is based on the following.

The image display device according to this embodiment includes a data signal line drive circuit as shown in FIG. This data signal line drive circuit has a serial-parallel conversion circuit 1, a decoding circuit 2, ..., A switch 3, ..., A gradation voltage setting circuit 4, and a data signal conversion circuit 5.

The serial-parallel converter circuit 1 converts the input serial display data signal (3-bit digital signal) into parallel data based on the control signal supplied through the control signal line, and outputs the data from each stage. It is designed to output to the terminal. The decoding circuit 2 outputs a decoding signal (switch control signal) for turning on a plurality of switches 3 ... Based on the signal output from the serial-parallel conversion circuit 1.

The switches 3 ... As selecting means are provided in the same number as the n gradation signal lines 6 provided, and each of them is connected to one gradation signal line 6. One of n switches of the switches 3 ... Is turned on by the decode signal from the decoding circuit 2, and one of the grayscale signal lines 6 ...
The book is connected to the data signal line 7.

The portion composed of the serial-parallel conversion circuit 1, the decoding circuit 2, ... And the switch 3 ... Of the gradation signals representing n kinds of gradations based on the input digital display data signal. One of them is supplied to the pixel and has a function as a digital / analog conversion means.

The gradation voltage setting circuit 4 as the gradation voltage setting means has (3n-1) / on each of the gradation signal lines 6 ...
Outputs a grayscale signal based on the effective voltage based on n types of original grayscale voltages set to 2 types (when n is an odd number) or 3n / 2 types (when n is an even number) It is supposed to do. Here, the effective voltage a (x) of the x (1 ≦ x ≦ n) -th gradation signal output from the gradation voltage setting circuit 4,
Corresponding combinations with the y-th original gradation voltage b (y) are the following two combinations, a first combination and a second combination. First combination y = (3x-1) / 2 (when x is an odd number) y = 3x / 2-1 (when x is an even number) second combination y = (3x-1) / 2 (where x is Y = 3x / 2 (when x is an even number) That is, the gradation voltage setting circuit 4 switches the combination of these and outputs the gradation signal.

The data signal conversion circuit 5 synchronizes the image data signal with the switching of the first combination and the second combination, and outputs the i-th image data signal at 1≤j when the first combination. It is adapted to be converted into the j-th display data signal of ≦ n and converted into the k-th display data signal of 1 ≦ k ≦ n and j−1 ≦ k ≦ j + 1 in the case of the second combination. In this transformation, there is a unique combination of j and k for i. In this way, the data signal conversion circuit 5 is configured to convert the display data signal into a combination of image data signals of which there are more types than the display data signal.

Here, the setting of the original gradation voltage b (y) will be described.

As shown in FIG. 2, when the applied voltage-transmittance characteristic of the liquid crystal element is linear, the voltage V _max that maximizes the transmittance and the voltage V _min that minimizes the transmittance are obtained.
The original gradation voltage is set by equally dividing the voltage V _max and the voltage V _min . This makes it possible to smoothly change the gradation display without reversing the magnitude relationship of the average voltage depending on the gradation.

Further, as shown in FIG. 3, when the applied voltage-transmittance characteristic of the liquid crystal element is non-linear, if the original grayscale voltage is set by dividing the voltage evenly, the transmittance between grayscales is increased. A large change and a small change appear. Therefore, the maximum transmittance T _max and the minimum transmittance T _min are obtained, and the maximum transmittance T _max and the minimum transmittance T _min are evenly divided,
The original gradation voltage is set to the applied voltage corresponding to each transmittance. As a result, the change in transmittance between gradations can be made constant, and gradation display can be changed smoothly.

However, as shown in FIG. 4, when the applied voltage-transmittance characteristic of the liquid crystal element has a linear portion and a non-linear portion, the voltage is divided evenly to obtain the original grayscale voltage. When set, some areas with large and small changes in transmittance appear between gradations, and when the original gradation voltage is set by dividing the transmittance evenly, the magnitude relationship of the average voltage is reversed depending on the gradation. To do. Therefore, the first voltage set by equally dividing the voltage V _max and the voltage V _min , and the respective transmissions when equally dividing the maximum transmittance T _max and the minimum transmittance T _min. The original gradation voltage is set in the middle of the second voltage set corresponding to the ratio. As a result, the magnitude relationship of the average voltage is not reversed depending on the gradation, and the gradation display can be smoothly changed with a constant change in the transmittance between the gradations.

In the above example, the case where the liquid crystal is used as the display element is explained, but the gradation is controlled by the effective voltage of the applied voltage such as EL display, LED display, FL display and plasma display. If so, the display element is not particularly limited. In the case of display elements other than liquid crystal, the light emission intensity, reflectance, etc. of the display element are used instead of the transmittance.

In the image display device configured as described above, for example, when n = 6, that is, when six kinds of gradation signals are input, the image data signals are shown in Table 3 by the data signal conversion circuit 5. As shown, it is converted in the first period and the second period, converted in parallel by the serial-parallel conversion circuit 1, and then input to the decoding circuits 2. The decode circuits 2 ... Output a decode signal based on the input signal. Then, based on the decoded signal, one switch 3 is turned on and the corresponding gradation signal line 6 is connected to the data signal line 7.

[0050]

[Table 3]

Grayscale voltages a (1) to a (6) (effective voltage of the grayscale signal) as shown in Table 4 are input to each of the grayscale signal lines 6 ... These gradation voltages a (1) to a
(6) is for the first period and the second period by the gradation voltage setting circuit 4.
, And the grayscale voltages corresponding to six original grayscale voltages selected from 9 (= 3 * 6/2) types of original grayscale voltages b (1) to b (9).

[0052]

[Table 4]

As a result, the gradation signal selected based on the image data signal converted as described above is output to the data signal line 7 as shown in Table 5 and supplied to the pixel (not shown). It As a result, the first period and the second
Images of 16 types of gradation can be displayed by the average voltage during the period.

[0054]

[Table 5]

As described above, in the present image display device, the gradation voltage setting circuit 4 switches between the first combination and the second combination, and further, the first combination based on the display data signal from the data signal conversion circuit 5. It is possible to obtain a sufficient number of gradations by supplying the k-th gradation signal in the period and the k-1 to k + 1-th gradation signals in the second period. Therefore, it is possible to perform multi-gradation display without increasing the number of gradation signal lines 6. Further, by limiting the combination of the gradation signals applied to the pixels in the first period and the second period as described above, the difference in the effective voltage of the gradation signals applied to the pixels for each vertical scanning period. Can be reduced, and flicker can be reduced.

By the way, if the image display device has a display element for driving a pixel by a DC voltage, the above first
It is sufficient to always apply the grayscale signals of the same polarity to the grayscale signal lines 6 ... In the period and the second period, but a display element such as a liquid crystal must drive the pixels with an AC signal. Therefore, in this embodiment, when the liquid crystal element is used, the gradation voltage setting circuit 4 as the gradation voltage setting means is configured to output the AC-converted gradation signal.

For example, the combination of the effective voltage and the original grayscale voltage of the grayscale signal output to the grayscale signal line 6 by the grayscale voltage setting circuit 4 when a certain pixel is scanned is at least one vertical scan. The combination is different from the combination when the same pixel is scanned before the period. Also,
In the first and second vertical scanning periods, the polarity of the gradation signal when at least the same pixel is scanned is positive, and in the third and fourth vertical scanning periods, the gradation when at least the same pixel is scanned. Make the signal polarity negative. As a result, a signal as shown in FIG. 5 is applied to the pixel. Therefore, in the first vertical scanning period and the third vertical scanning period, the pixels are AC-driven by applying signals having the same effective voltage but different polarities, and even in the second vertical scanning period and the fourth vertical scanning period, Similarly, it is driven by alternating current.

In addition to the above driving method, the following driving method is also available. That is, the polarity of the gradation signal when a certain pixel is scanned is set to be opposite to the polarity when the same pixel is scanned at least one vertical scanning period before. In addition to this, in the first and second vertical scanning periods,
The combination of the effective voltage and the original gradation voltage of the gradation signal output to the gradation signal line 6 by the gradation voltage setting circuit 4 when at least the same pixel is scanned becomes the first combination, and the third and In the fourth vertical scanning period, at least when the same pixel is scanned, the above combination is the second combination.
Be a combination of. As a result, a signal as shown in FIG. 6 is applied to the pixel. Therefore, in the first vertical scanning period and the second vertical scanning period, the pixels are AC-driven by applying signals having the same effective voltage and different polarities, and even in the third vertical scanning period and the fourth vertical scanning period, Similarly, it is driven by alternating current.

[Second Embodiment] The following will describe another embodiment of the present invention with reference to FIGS. 2 to 7. In the present embodiment, constituent elements having the same functions as those of the constituent elements of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The image display device according to this embodiment includes a data signal line drive circuit as shown in FIG. This data signal line drive circuit has a series-parallel conversion circuit 1, a decoding circuit 2, ..., A switch 3, ..., A gradation voltage setting circuit 11, and a data signal conversion circuit 12.

The gradation voltage setting circuit 11 as the gradation voltage setting means has (3n-1) for each of the gradation signal lines 6 ...
N of the original gradation voltages set to / 2 types (when n is an odd number) or 3n / 2-1 types (when n is an even number)
A grayscale signal based on the effective voltage based on the original grayscale voltage of the type is output. Here, the gradation voltage setting circuit 11
The combination of the effective voltage a (x) of the x (1 ≦ x ≦ n) -th gray scale signal output by and the corresponding y-th original gray scale voltage b (y) is as follows. . y = (3x−1) / 2 (when x is an odd number) y = 3x / 2−1 (when x is an even number) Here, the original grayscale voltage is the same as in the first embodiment shown in FIGS. Is set according to one of the characteristics of

The data signal conversion circuit 12 basically has
It has the same function as the configuration in the first embodiment, but the i-th image data signal is
The j-th display data signal of j ≦ n is converted into the k-th display data signal of j ≦ k ≦ j + 2 in the second period. In this conversion, i
There is a unique combination of j and k for. In this way, the data signal conversion circuit 12 is adapted to convert the display data signal into a combination of image data signals of which there are more types than the display data signal.

In the image display device configured as described above, when six kinds of gradation signals are input (n = 6),
The image data signal is shown in Table 6 by the data signal conversion circuit 12.
Is converted in the first period and the second period as shown in
After being converted in parallel by the serial-parallel conversion circuit 1, it is input to the decoding circuits 2. Then, one switch 3 is turned on based on the decode signal output from the decode circuit 2 ... Based on the input signal, and the gradation signal is applied to the data signal line 7 via the switch 3.

[0064]

[Table 6]

Grayscale voltages a (1) to a (6) as shown in Table 7 are input to each of the grayscale signal lines 6 ... These gradation voltages a (1) to a (6) are applied to the gradation voltage setting circuit 1
1 by 8 in the first period and the second period, respectively.
(= 3 * 6 / 2-1) kinds of original gradation voltages b (1) to b (8)
6 original gradation voltages selected from b (1), b (2), and b (4)
・ B (5) ・ b (7) ・ b (8) corresponding to the gradation voltage.

[0066]

[Table 7]

As a result, the gradation signal selected based on the image data signal converted as described above is output to the data signal line 7 as shown in Table 8 and supplied to the pixel. As a result, it is possible to display an image of 15 kinds of gradations by the average voltage of the first period and the second period.

[0068]

[Table 8]

Also in this embodiment, similarly to the first embodiment, when a display element that needs to be driven by alternating current is used, alternating current driving as shown in FIG. 5 or 6 is performed.

As described above, in the present image display device, the grayscale voltage setting circuit 11 outputs the same grayscale signal in the first period and the second period, and the display data from the data signal conversion circuit 12 is further output. A sufficient number of gray levels can be obtained by supplying the kth grayscale signal in the first period and the k-2 to k + 2th grayscale signal in the second period based on the signal. . Therefore, it is possible to perform multi-gradation display without increasing the number of gradation signal lines 6.

In the image display device of the present embodiment, as described above, sufficient gradations are output in order to output the same gradation signal from the gradation voltage setting circuit 11 in the first period and the second period. In order to obtain it, it is necessary to supply more kinds of gradation signals than the image display device of the first embodiment in the second period. However, according to the image display device of the present embodiment, the gradation voltage setting circuit 11 does not need to switch the effective voltage of the gradation signal for each vertical period, and the gradation voltage setting circuit 11
The operation can be simplified as compared with the operation of the gradation voltage setting circuit 4 (see FIG. 1).

[0072]

As described above, the image display apparatus according to the first aspect of the present invention provides one of the gradation signals representing n kinds of gradations based on the input digital display data signal. Digital / analog conversion means for supplying the pixel, n
The effective voltage of each kind of gradation signal is set in a one-to-one correspondence with the n kinds of original gradation voltages among the m kinds of original gradation voltages where n <m, and is given to the digital / analog conversion means.
The gradation voltage setting means for switching the correspondence between the two combinations of the first combination and the second combination, and the i-th image data signal of the p types of image data signals where n <m <p are the above-mentioned first When the combination is taken, 1 ≦ j ≦ n
While converting to the j-th display data signal
1 ≦ k ≦ n and j−1 ≦
Data conversion means for converting the k-th display data signal of k ≦ j + 1 to the digital / analog conversion means and giving a 1: 1 combination of j and k for i is provided, and the same pixel is scanned. At this time, the combination of the effective voltage of the gradation signal and the original gradation voltage is set to be 1: 1 in the case of the first combination and in the case of the second combination. It is a composition.

Thus, the first combination or the second
With the combination of the gradation signals applied to the pixels when the combination is selected, it is possible to increase the number of gradations that can be expressed with a small number of gradation signals.
Further, when the image data signals of the pixels are the same, the difference in effective voltage of the gradation signals output in the case of the first combination and the case of the second combination becomes small. It is possible to reduce the difference in the effective voltage of the gradation signal applied to, and to suppress flicker.

An image display device according to a second aspect of the present invention is the image display device according to the first aspect, wherein the gradation voltage setting means is configured as follows. That is, the gradation voltage setting means is such that when n is an odd number, m =
(3n-1) / 2, and when n is an even number, m = 3n / 2
On the other hand, the effective voltage a (x) of the x-th gradation signal, where 1 ≦ x ≦ n, and the corresponding y-th original gradation voltage b.
When the combination with (y) is the first combination, y = (3x−1) / 2 (when x is an odd number) and y = 3x / 2−1 (when x is an even number). On the other hand, when it is the second combination, y
= (3x-1) / 2 (when x is an odd number) and y = 3x
/ 2 (when x is an even number).

As a result, the combinations of the effective voltages of the gradation signals applied in the first combination period and the second combination period can be made different according to the image data signal. -1) There is an effect that it is possible to display +1 types of images having different gradations.

An image display device according to a third aspect of the present invention is a digital / analog which supplies one of gradation signals representing n kinds of gradations to a pixel based on an input digital display data signal. The conversion means and n out of m kinds of original gradation voltages where n <m are effective voltages of n kinds of gradation signals.
The gradation voltage setting means for setting a one-to-one correspondence with the original gradation voltages of the types, and the i-th image data signal of the p types of image data signals where n <m <p are set in the first period. 1 ≦
While converting to the j-th display data signal of j ≦ n, it is converted to the k-th display data signal of 1 ≦ k ≦ n and j ≦ k ≦ j + 2 in the second period and given to the digital / analog conversion means. , I and a data conversion means for making the combination of j and k for i to be one-to-one, and the combination of the image data signal and the display data signal when the same pixel is scanned is the first period and the first period. This is a configuration that is set to be one-to-one in two periods.

As described above, it is possible to increase the number of gradations that can be expressed by a small number of gradation signals by combining the gradation signals applied to the pixels in the first period and the second period. Play. Further, when the image data signals of the pixels are the same, the difference between the effective voltages of the gradation signals output in the first period and the second period becomes small, so that the pixel signals are applied to the pixels every vertical scanning period. The effect that the difference in effective voltage of the gradation signals can be made small and flicker can be made small is also exhibited.

An image display device according to a fourth aspect of the present invention is the image display device according to the third aspect, wherein the gradation voltage setting means is configured as follows. That is, the gradation voltage setting means is such that when n is an odd number, m =
(3n-1) / 2, and when n is an even number, m = 3n / 2
On the other hand, the combination of the effective voltage a (x) of the x-th gradation signal satisfying 1 ≦ x ≦ n and the corresponding y-th original gradation voltage b (y) corresponding thereto is y = ( 3x-1) / 2 (when x is an odd number) and y = 3x / 2-1 (when x is an even number).

As a result, all combinations of effective voltages of the gradation signals applied in the first period and the second period can be made different, and images of 3 (n-1) different gradations can be obtained. It is possible to display.

An image display device according to a fifth aspect of the present invention is the image display device according to any one of the first to fourth aspects, in which the gradation voltage setting means is configured as follows. . That is, the gradation voltage setting means has the same polarity in the first vertical scanning period and the second vertical scanning period and the same polarity in the third vertical scanning period and the fourth vertical scanning period when the same pixel is scanned. Gradation so that the polarities are the same, but the magnitudes are the same in the first vertical scanning period and the third vertical scanning period, and the polarities are the same, and the magnitudes are the same and the polarities are different in the second vertical scanning period and the fourth vertical scanning period. It is designed to set the effective voltage of the signal.

Thus, the display element can be driven by an AC signal, and even when a display element such as a liquid crystal which needs to be driven by an AC signal is used, the display element can be driven by any one of claims 1 to 4.
As in the image display device described in any one of the above, there is an effect that the number of gradations can be increased.

An image display device according to a sixth aspect of the present invention is the image display device according to any one of the first to fourth aspects, in which the gradation voltage setting means is configured as follows. . That is, the gradation voltage setting means has the same polarity in the first vertical scanning period and the third vertical scanning period and the same polarity in the second vertical scanning period and the fourth vertical scanning period when the same pixel is scanned. Gradation so that the polarities are the same, but the magnitudes are equal and different between the first vertical scanning period and the second vertical scanning period, and the magnitudes are equal and different between the third vertical scanning period and the fourth vertical scanning period. It is designed to set the effective voltage of the signal.

As a result, similar to the image display device described in claim 5, even when a display element that needs to be driven by an AC signal is used, it is similar to the image display device described in any one of claims 1 to 4. In addition, the number of gradations can be increased.

An image display device according to a seventh aspect of the present invention is the image display device according to any one of the first to sixth aspects, wherein the gradation voltage setting means is a dynamic drive voltage of a display element. The original gradation voltage is set to a value obtained by evenly dividing the range.

As a result, when the relationship between the transmittance and the like and the drive voltage of the display element is linear, the change in the transmittance and the like between gradations can be made constant, and the display gradation can be changed smoothly. There is an effect that can be made.

An image display device according to an eighth aspect of the present invention is the image display device according to any one of the first to sixth aspects, in which the gradation voltage setting means has a light emission intensity of a display element and a transmission factor. The original gradation voltage is set to a value obtained by evenly dividing the dynamic range of the reflectance or reflectance.

Thus, when the relationship between the transmittance and the like and the drive voltage of the display element is non-linear, the change in the transmittance and the like between gradations can be made constant, and the display gradation can be smoothed. The effect that it can be changed is produced.

An image display device according to a ninth aspect of the present invention is the image display device according to any one of the first to sixth aspects, wherein the gradation voltage setting means is a dynamic drive voltage of a display element. The original voltage is set to an intermediate value between the first voltage set by equally dividing the range and the second voltage set by equally dividing the dynamic range of the emission intensity, the transmittance, or the reflectance of the display element. The gradation voltage is set.

Thus, when there is a linear portion or a non-linear portion in the relationship between the transmittance and the driving voltage of the display element, the change in the transmittance and the like between gradations can be made constant. Therefore, the display gradation can be smoothly changed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a data signal line drive circuit of an image display device according to an embodiment of the present invention.

FIG. 2 is common to one embodiment and another embodiment of the present invention, and when a display element is a liquid crystal, the applied voltage is divided evenly to set an original gradation voltage. It is a graph which shows a transmittance characteristic.

FIG. 3 is common to one embodiment and another embodiment of the present invention, and is an applied voltage when the original gradation voltage is set by equally dividing the transmittance when the display element is a liquid crystal. It is a graph which shows a transmittance characteristic.

FIG. 4 is common to one embodiment and another embodiment of the present invention, in which when a display element is a liquid crystal, an applied voltage is equally divided and a set voltage and transmittance are equally divided. 7 is a graph showing applied voltage versus transmittance characteristics when an original gradation voltage is set with the voltage set by the above.

FIG. 5 is a waveform chart common to one embodiment of the present invention and other embodiments and showing an example of an AC signal applied to a pixel.

FIG. 6 is a waveform chart common to one embodiment of the present invention and another embodiment and showing another example of an AC signal applied to a pixel.

FIG. 7 is a block diagram showing a configuration of a main part of a data signal line drive circuit of an image display device according to another embodiment of the present invention.

FIG. 8 is a block diagram showing a display panel and a drive circuit in a general matrix type image display device.

FIG. 9 is a block diagram showing a configuration of a conventional data signal line drive circuit.

FIG. 10 is a block diagram showing a configuration of another conventional data signal line drive circuit.

11 is a waveform diagram showing an output signal (modulation signal) of the pulse width modulation circuit in the data signal line drive circuit of FIG. 10 and a gradation signal input to the data signal line drive circuit.

[Explanation of symbols]

 1 serial-parallel conversion circuit 2 decoding circuit 3 switch 4 gradation voltage setting circuit (gradation voltage setting means) 5 data signal conversion circuit (data conversion means) 6 gradation signal line 7 data signal line 11 gradation voltage setting circuit ( Gradation voltage setting means) 12 data signal conversion circuit (data conversion means)

Claims (9)

[Claims] 1. A digital / analog converting means for supplying to a pixel one of gradation signals representing n kinds of gradations based on an input digital display data signal, and an effective operation of the n kinds of gradation signals. The voltage is set by a one-to-one correspondence with the n kinds of original gradation voltages among the m kinds of original gradation voltages with n <m, and is given to the digital / analog conversion means, and the correspondence is the first combination. And a gradation voltage setting means for switching between two ways of a second combination, and an i-th image data signal of p types of image data signals where n <m <p is 1 ≦ when the first combination is taken. While converting to the j-th display data signal with j ≦ n, 1 ≦ k ≦ n when the second combination is taken.
Further, it is converted into a k-th display data signal satisfying j−1 ≦ k ≦ j + 1 and given to the digital / analog converting means, i
Data conversion means for making the combination of j and k with respect to 1 to 1 one to one, and the combination of the effective voltage of the grayscale signal and the original grayscale voltage when the same pixel is scanned is the first 1 depending on the combination and the second combination
An image display device, characterized in that the image display device is set to be 1: 1. 2. The gradation voltage setting means sets m = (3n-1) / 2 when n is an odd number, and m = 3 when n is an even number.
On the other hand, the combination of the effective voltage a (x) of the x-th gradation signal satisfying 1 ≦ x ≦ n and the y-th original gradation voltage b (y) corresponding thereto is set to n / 2. In the case of the combination of 1, y = (3x-1) / 2 (when x is an odd number) and y = 3x / 2-1 (when x is an even number). The image according to claim 1, characterized in that y = (3x-1) / 2 (when x is an odd number) and y = 3x / 2 (when x is an even number). Display device. 3. Digital / analog converting means for supplying to the pixel one of the gradation signals representing n kinds of gradations based on the input digital display data signal, and the effect of the n kinds of gradation signals. Gradation voltage setting means for setting a voltage in a one-to-one correspondence with n kinds of original gradation voltages of m kinds of original gradation voltages of n <m, and p kinds of images of n <m <p The i-th image data signal of the data signals is converted into the j-th display data signal of 1 ≦ j ≦ n in the first period, while 1 ≦ k in the second period.
It is converted into a k-th display data signal satisfying ≤n and j≤k≤j + 2 and given to the digital / analog converting means, i
Data conversion means for making the combination of j and k for 1 to 1 with respect to each other, the combination of the image data signal and the display data signal when the same pixel is scanned is the first period and the second An image display device, wherein the image display device is set to have a one-to-one correspondence with a period. 4. The gradation voltage setting means sets m = (3n-1) / 2 when n is an odd number, and m = 3 when n is an even number.
n / 2−1, while a combination of the effective voltage a (x) of the xth gradation signal satisfying 1 ≦ x ≦ n and the corresponding yth original gradation voltage b (y), 4. The image display device according to claim 3, wherein the image display device is determined by a relationship of y = (3x-1) / 2 (when x is an odd number) and y = 3x / 2-1 (when x is an even number). . 5. The gradation voltage setting means has the same polarity in the first vertical scanning period and the second vertical scanning period when the same pixel is scanned, and the third vertical scanning period and the fourth vertical scanning period. And have the same polarity, while the first vertical scanning period and the third vertical scanning period have the same size and different polarities, and the second vertical scanning period and the fourth vertical scanning period have the same size and different polarities. 5. The image display device according to claim 1, wherein the effective voltage of the gradation signal is set to. 6. The gradation voltage setting means has the same polarity in the first vertical scanning period and the third vertical scanning period when the same pixel is scanned, and the second vertical scanning period and the fourth vertical scanning period. And have the same polarity, while the first vertical scanning period and the second vertical scanning period have the same size and different polarities, and the third vertical scanning period and the fourth vertical scanning period have the same size and different polarities. 5. The image display device according to claim 1, wherein the effective voltage of the gradation signal is set to. 7. The gradation voltage setting means sets the original gradation voltage to a value obtained by evenly dividing a dynamic range of a drive voltage of a display element.
The image display device according to any one of 1. 8. The gradation voltage setting means sets the original gradation voltage to a value obtained by evenly dividing a dynamic range of light emission intensity, transmittance or reflectance of a display element. 7. The image display device according to any one of 1 to 6. 9. The gradation voltage setting means sets a first voltage which is set by equally dividing a dynamic range of a drive voltage of a display element and a dynamic range of light emission intensity, transmittance or reflectance of the display element. 7. The image display device according to claim 1, wherein the original gradation voltage is set to an intermediate value with respect to a second voltage which is set by evenly dividing.